EP0418818B1 - Ink-jet recording apparatus and temperature control method therefor - Google Patents

Abstract

An ink-jet recording apparatus for discharging an ink droplet from a recording head (2) to perform recording includes a heating element array (13) for heating the recording head, a temperature sensor (8) for measuring an ambient temperature, a timer for measuring a time associated with a temperature variation of the recording head (2) during a recording operation, and a control unit for controlling an energy supplied to the heating element array (13) on the basis of the ambient temperature measured by the temperature sensor (8) and the time measured by the timer.

Description

BACKGROUND OF THE INVENTIONField of the Invention

The present invention relates to an ink-jetrecording apparatus for causing a recording head todischarge an ink to a recording medium to performrecording, and a temperature control method therefor.

Related Background Art

A recording apparatus such as a printer, a copyingmachine, a facsimile apparatus, or the like records animage consisting of a dot pattern on a recording mediumsuch as a paper sheet or a plastic thin plate.

The recording apparatus can be classified as anink-jet type, wire dot type, thermal type, laser-beamtype, and the like according to a recording method. Ofthese apparatuses, in the ink-jet type apparatus(ink-jet recording apparatus), an ink droplet(recording liquid) is discharged and flied from adischarge port of a recording head, and is attached toa recording medium, thereby performing recording.

In recent years, a large number of recordingapparatuses have been used, and are required to have ahigh recording speed, a high resolution, high imagequality, and low noise.

As a recording apparatus which satisfies these requirements, the ink-jet recording apparatus is known.

In the ink-jet recording apparatus, sincerecording is performed by discharging an ink from arecording head, the apparatus is considerablyinfluenced by the temperature of the recording head.

For this reason, a conventional ink-jet recordingapparatus employs a so-called closed-loop controlmethod wherein a temperature sensor and a temperaturecontrol heater which increase cost are arranged in arecording head unit, so that the temperature of therecording head is controlled to fall within a desiredrange on the basis of the detected temperature of therecording head. As the temperature control heater, aheating heater member joined to a recording head unitor a discharge heater in a bubble-jet recordingapparatus, proposed by CANON INC.in DE-A-3545689,for discharging anink droplet by growing bubbles by film boiling of anink is used. When the discharge heater is used, itmust be energized so as not to generate bubbles.

In particular, in a bubble-jet recording apparatus(which is proposed by CANON INC., and forms bubbles ina solid-state or liquid ink using a heat energy toobtain an ink droplet to be discharged), since itsdischarge characteristics are largely varied dependingon the temperature of the recording head, as isconventionally known, closed-loop temperature controltends to be performed. Alternatively, only an inexpensive printer which is used for a compactelectronic calculator which disregards printingquality, density nonuniformity, and the like isavailable.

However, in recent years, since portable OAequipments such as laptop personal computers havebecome popular, portable printers are required to havehigh quality. A disposable cartridge type printer inwhich a head and an ink tank are integrated will leadthe portable printers since it has a compact structure.In addition, the disposable cartridge type printer willbecome more popular in terms of maintenance due to anincrease in popularity of home- or personal-usewordprocessors, personal computers, facsimileapparatuses.

In this case, since the temperature sensor and theheater for temperature control are incorporated in thedisposable cartridge, the following drawbacks areposed.

(1) Variation in temperature measurement values due tovariation in temperature sensor

Since a disposable head is an expendable supply, asensor having a variation in characteristics isconnected to the printer main body every time the headis exchanged.

In a bubble-jet recording head, since a dischargeheater is manufactured in a semiconductor process, a diode sensor for detecting a temperature of a recordinghead must be integrally formed in a single process todecrease cost. Since the diode sensor suffers from avariation in the manufacture, it does not have highprecision like in a temperature sensor as a selectedproduct, and may often cause a difference of 15°C ormore among manufacturing lots as measurement values ofan ambient temperature.

For this reason, closed-loop control using thetemperature sensor of the recording head requires acomplicated adjustment operation for adjusting avariation in temperature sensor of the recording headin an adjustment process, or mounting a temperaturesensor which is measured and ranked in a main body, andcorrecting it using an adjustment selection switch.

These operations considerably increasemanufacturing cost, and impair operability. Anincrease in signal processing volume caused by theseoperations, and a considerable increase in processingvolume of an MPU caused by closed-loop control itselfexert a heavy load on design of a compact or portableprinter main body apparatus.

(2) Countermeasure against electrostatic noise

Since a disposable head is an expendable supply, auser frequently attaches or detaches it to or from amain body. For this reason, contacts of the main bodyare always exposed.

Since the output from the temperature sensor isdirectly supplied to a circuit on a printed circuitboard of the main body through a carriage and aflexible wiring, a temperature measurement circuit isvery weak against electrostatic noise. Since a compactor portable printer cannot have a sufficient shieldeffect in its housing, it is further weak againstelectrostatic noise.

Therefore, in a conventional temperature detectionmethod, an electrostatic shield, and parts as acountermeasure against electrostatic noise must beadded at respective portions for only a singletemperature sensor, thus considerably disturbing acompact structure, a decrease in cost, and high imagequality.

SUMMARY OF THE INVENTION:

It is a principal object of the present inventionto provide an ink-jet recording apparatus which cancontrol a temperature of a recording head to fallwithin a desired range without arranging a temperaturesensor in the recording head, and a temperature controlmethod therefor.

It is another object of the present invention toprovide an ink-jet recording apparatus which cancontrol a temperature of a recording head to fallwithin a desired range even when a print rate ischanged, and a temperature control method therefor.

It is still another object of the presentinvention to provide an ink-jet recording apparatuswhich can control a temperature of a recording head tofall within a desired range even when a differencebetween a temperature in the recording apparatus and atemperature of the recording head occurs, and atemperature control method therefor.

It is still another object of the presentinvention to provide an ink-jet recording apparatuswhich can prevent a temperature of a recording headfrom being increased to an abnormal high temperature,and a temperature control method therefor.

This objects are achieved by an ink-jet recording apparatushaving the features indicated inclaims 1, 24 or 35.

The invention is further developed by the features mentioned in the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a schematic perspective view of anarrangement suitable for the present invention;

Fig. 2 is an exploded perspective view of acartridge suitable for the present invention;

Fig. 3 is a perspective view showing an assemblyof the cartridge shown in Fig. 2;

Fig. 4 is a perspective view of a mounting portionof an ink-jet unit IJU;

Fig. 5 is a view for explaining a mountingoperation of the cartridge IJU to an apparatus;

Fig. 6 is a perspective view showing an outerappearance of an apparatus suitable for the presentinvention;

Fig. 7 is a perspective view of a recording head;

Fig. 8 is a sectional view showing in detailFig. 7;

Fig. 9 is a sectional view showing anotherarrangement of the recording head;

Fig. 10 is a graph showing a change in temperatureof the recording head obtained when temperature controlbefore printing is performed;

Figs. 11 and 17 are graphs showing a change intemperature of the recording head obtained when onlytemperature control during printing is performed;

Figs. 12 and 18 are graphs showing a change intemperature control of the recording head obtained whenonly temperature control before printing andtemperature control during printing are performed;

Fig. 13 is a graph showing a change in temperatureof the recording head obtained when no temperaturecontrol is performed;

Fig. 14 is a graph showing a change in temperatureof the recording head obtained when a print operationis performed according to the first embodiment;

Fig. 15 is a flow chart showing temperaturecontrol according to the first embodiment of thepresent invention;

Fig. 16 is a graph showing an over heat state ofthe recording head;

Figs. 19A to 19C are graphs showing a change intemperature of the recording head obtained whenprinting is performed according to the secondembodiment of the present invention;

Fig. 20 is a flow chart showing temperaturecontrol according to the second embodiment of thepresent invention;

Fig. 21 is a block diagram showing a controlarrangement suitable for the present invention;

Figs. 22, 23, and 25 are graphs showing a changein temperature in the machine near a temperaturesensor, and a change in temperature of the recordinghead;

Fig. 24 is a flow chart showing temperaturecontrol according to the third embodiment of thepresent invention;

Fig. 26 is a graph showing a change in temperaturein the machine near a temperature sensor and a changein correction temperature;

Fig. 27 is a timing chart showing timings forperforming temperature control;

Fig. 28 is a timing chart showing output timingsof temperature control pulses;

Fig. 29 is a flow chart showing temperaturecontrol according to the fourth embodiment of thepresent invention;

Fig. 30 is a graph showing an equilibratedtemperature of a recording head according to a printrate;

Fig. 31 is a graph showing an increase and adecrease in temperature of the recording head accordingto the print rate;

Figs. 32 and 33 are flow charts showingtemperature control according to the fifth embodimentof the present invention;

Fig. 34 is a perspective view showing an ink-jetrecording apparatus suitable for carrying outtemperature control according to the sixth embodimentof the present invention;

Fig. 35 is a partial perspective view showing astructure of a recording head shown in Fig. 34;

Fig. 36 is a graph showing the relationshipbetween a temperature of the recording head shown inFig. 34 and a temperature of a power transistor fordriving a discharge heater;

Fig. 37 is a block diagram showing a temperature control system of the recording head shown in Fig. 34;

Fig. 38 is a partial perspective view showing astructure of a recording head for performingtemperature control according to the seventh embodimentof the present invention;

Fig. 39 is a sectional view of a printed circuitboard according to the seventh embodiment of thepresent invention;

Fig. 40 is a block diagram of a temperaturecontrol system according to the seventh embodiment ofthe present invention;

Figs. 41A and 41B are sectional views of a printedcircuit board used in the eighth embodiment of thepresent invention;

Fig. 42 is a sectional view of a printed circuitboard used in the ninth embodiment of the presentinvention; and

Fig. 43 is a block diagram of a control systemaccording to the ninth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Figs. 2 to 6 are views for explaining an ink-jetunit IJU, an ink-jet head IJH, an ink tank IT, anink-jet cartridge IJC, an ink-jet recording apparatusmain body IJRA, and a carriage HC, and the relationshipamong these components. The arrangement of theseportions will be described below with reference to Figs. 2 to 6.

The ink-jet cartridge IJC in this embodiment hasan increased ink storage ratio, as can be seen from theperspective view of Fig. 3, and has a shape in whichthe distal end portion of the ink-jet unit IJU slightlyprojects from the front surface of the ink tank IT.The ink-jet cartridge IJC is fixed and supported by apositioning means and electrical contacts (to bedescribed later) of the carriage HC (Fig. 5) placed onthe ink-jet recording apparatus main body IJRA, and isof a disposable type which can be detachable from thecarriage HC. Since Figs. 2 to 6 of this embodimentshow arrangements to which various inventions whichhave been made in establishment of the presentinvention are applied, the overall arrangement will bedescribed below while briefly explaining thesearrangements.

(i) Arrangement of Ink-jet Unit IJU

The ink-jet unit IJU is a bubble-jet type unit forperforming recording using an electrothermal conversionelement for generating a heat energy for causing filmboiling of an ink according to an electrical signal.

In Fig. 2, aheater board 100 is prepared byforming a plurality of electrothermal conversionelement arrays (discharge heater), a temperaturecontrol heater, and Al electrical wirings for supplyingan electric power to these heaters on an Si substrate by a film formation technique. Awiring circuit board200 is arranged for theheater board 100, and haswirings corresponding to those of the heater board 100(e.g., these wirings are connected by wire bonding),andpads 201, located at the end portions of thesewirings, for receiving electrical signals from theapparatus main body.

A groovedtop plate 1300, on which partition wallsfor dividing a plurality of ink paths, a common inkchamber, and the like are arranged, is formed byintegrally molding anink reception port 1500 forreceiving an ink supplied from the ink tank and guidingit to the common ink chamber, and anorifice plate 400having a plurality of discharge ports. As a materialfor integrally molding these components, polysulfone ispreferable, but other molding resin materials may beused.

Ametal support member 300 supports the rearsurface of thewiring circuit board 200 on a plane, andserves as a bottom plate of the ink-jet unit. Apressing spring 500 has an M shape, and presses thecommon ink chamber at the central portion of its "M" shapeat a low pressure. In addition, anapron portion 501of thespring 500 presses a portion of an ink path at aline pressure. The leg portions of the pressing springare engaged with the rear surface side of thesupportmember 300 viaholes 3121 of thesupport member 300 to sandwich theheater board 100 and thetop plate 1300therebetween, thereby engaging these components. Thus,theheater board 100 and thetop plate 1300 are pressedand fixed by the biasing force of thepressing spring500 and itsapron portion 501. Thesupport member 300haspositioning holes 312, 1900, and 2000 which arerespectively engaged with the twopositioningprojections 1012 of the ink tank IT, and positioningand thermalfusion bonding projections 1800 and 1801.Thesupport member 300 also haspositioning projections2500 and 2600 for the carriage HC of the apparatus mainbody IJRA on its rear surface. In addition, thesupport member 300 has ahole 320 for allowing an inksupply pipe 2200 (to be described later) extendingtherethrough to supply an ink from the ink tank. Thewiring circuit board 200 is mounted on thesupportmember 300 by adhesion using an adhesive. Note thatrecess portions 2400 of thesupport member 300 areformed near thepositioning projections 2500 and 2600.These recess portions are present on a plurality ofextending lines ofparallel grooves 3000 and 3001formed on the three side surfaces around the distal endregion of the head portion of the assembled ink-jetcartridge IJC (Fig. 3). For this reason, unnecessarymatters such as dust or an unnecessary ink moved alongtheparallel grooves 3000 and 3001 are prevented fromreaching theprojections 2500 and 2600. Alid member 800 on which theparallel groove 3000 is formed definesan outer wall of the ink-jet cartridge IJC, as can beseen from Fig. 5, and also defines a space portion forstoring the ink-jet unit IJU together with the ink tankIT. Anink supply member 600 on which theparallelgroove 3001 is formed forms anink guide pipe 1600continuous with theink supply pipe 2200 as acantilever which is fixed at thesupply pipe 2200 side,and asealing pin 602 for assuring a capillaritybetween the fixed portion of the ink guide pipe and theink supply pipe 2200 is inserted in themember 600.Note that a packing 601 provides a coupling sealbetween the ink tank IT and thesupply pipe 2200, and afilter 700 is arranged at the end portion on the sideof the tank of the supply pipe.

Since theink supply member 600 is formed bymolding, it is inexpensive, has high positioningprecision, and can eliminate a decrease in precision inthe manufacture. In addition, since theink guide pipe1600 has a cantilever structure, a pressing contactstate of theguide pipe 1600 against theink receptionport 1500 can be stabilized. Thus, theink supplymember 600 is also suitable for mass-production. Inthis embodiment, a sealing adhesive is fed from the inksupply member side in this pressing contact state, thusreliably attaining a complete communication state. Theink supply member 600 can be easily fixed to thesupport member 300 in such a manner that pins (notshown) on the rear surface of the ink supply memberproject throughholes 1901 and 1902 of thesupportmember 300, and the projecting portions on the rearsurface of thesupport member 300 are thermally fused.The small thermally fused projection regions on therear surface portion can be housed in a recess (notshown) of the wall surface of the ink tank IT on whichthe ink jet unit IJU is mounted. Therefore, apositioning surface of the unit IJU can be preciselyobtained.

(ii) Arrangement of Ink Tank IT

The ink tank is constituted by a cartridgemainbody 1000, anink absorber 900, and alid member 1100for sealing theink absorber 900 after the ink absorberis inserted from a side surface opposite to the unitIJU mounting surface of the cartridgemain body 1000.

Theink absorber 900 impregnates an ink, and isarranged in the cartridgemain body 1000. Asupplyport 1200 supplies an ink to the unit IJU consisting ofthecomponents 100 to 600, and also serves as aninjection port. That is, when an ink is injected fromthesupply port 1200 before the unit is arranged on aportion 1010 of the cartridgemain body 1000, an ink isimpregnated in theabsorber 900.

In this embodiment, portions capable of supplyingan ink are anair communication port 1401 and thissupply port 1200. In order to satisfactorily supply anink from the ink absorber, an intra-tank air regiondefined byribs 2300 in themain body 1000 andpartialribs 2301 and 2302 of thelid portion 1100 is formed tobe continuous with theair communication port 1401 sideover a corner area farthest from theink supply port1200. Therefore, it is important to relativelysatisfactorily and uniformly supply an ink to theabsorber from the side of thesupply port 1200. Thismethod is very effective in a practical application.Theribs 2300 include four ribs parallel to the movingdirection of the carriage, which are formed on thesurface of the rear portion of the ink tankmain body1000 so as to prevent the absorber from being in rightcontact with the surface of the rear portion. Thepartial ribs 2301 and 2302 are similarly formed on theinner surface of thelid member 1100 on thecorresponding extending lines of theribs 2300, but aredivided unlike theribs 2300 to increase an air spaceas compared to theribs 2300. Note that thepartialribs 2301 and 2302 are dispersed on asurface portion1/2 or less the entire surface of thelid member 1100.With these ribs, an ink in a corner area farthest fromtheink supply port 1200 of the ink absorber canreliably guided toward thesupply port 1200 by acapillarity force while being stabilized. Theaircommunication port 1401 is formed in the lid member to cause the interior of the cartridge to communicate withouter air. Awaterproof member 1400 is arranged insidetheair communication port 1401 to prevent an ink fromleaking from theair communication port 1401.

An ink storage space of the ink tank IT has arectangular shape, and its long side corresponds to aside surface. Therefore, the above-mentionedarrangement of the ribs are particularly effective.When the storage space has a long side parallel to themoving direction of the carriage, or has a cubic shape,the ribs are formed on theentire lid member 1100 tostabilize ink supply from theink absorber 900. Inorder to store an ink in a limited space as much aspossible, a cubic shape is suitable. However, in orderto efficiently use the stored ink for recording, asdescribed above, it is important to form ribs capableof performing the above-mentioned operation on twosurface regions adjacent to the corner portion.Furthermore, theribs 2301 and 2302 on the innersurface of the ink tank IT in this embodiment arearranged at an almost uniform distribution with respectto the direction of thickness of thecubic ink absorber900. This structure is important since it can uniforman atmospheric pressure distribution with respect toink consumption of the overall absorber, and can makean ink residue almost zero.

Furthermore, the technical idea of the arrangement of the ribs will be described below in more detail.When an arc having a long side as a radius is drawn tohave a position obtained by projecting theink supplyport 1200 of the ink tank onto the square upper surfaceof the cube as the center, it is important to arrangethe above-mentioned ribs on a surface portion outsidethe arc so that an atmospheric pressure is givenearlier to the absorber portion located outside thearc. In this case, the position of theaircommunication port 1401 of the tank is not limited tothat of this embodiment as long as air can beintroduced to the rib arrangement region.

In this embodiment, the ink-jet cartridge IJC hasa flat rear surface portion with respect to the head tominimize a necessary space when it is assembled in theapparatus, and to maximize an ink storage amount.Therefore, the cartridge of this embodiment has anexcellent structure since the apparatus can be renderedcompact, and an exchange frequency of cartridges can bedecreased. A projecting portion for theaircommunication port 1401 is formed by utilizing a rearportion of a space for integrating the ink-jet unitIJU, and the interior of the projecting portion ishollowed to form an atmosphericpressure supply space1402 for the total thickness of theabsorber 900, asdescribed above. With this arrangement, an excellentcartridge which cannot be realized by the conventional technique can be provided.

Note that the atmosphericpressure supply space1402 is considerably larger than a conventional one,and theair communication port 1401 is located abovethis space. Therefore, even if an ink is released fromthe absorber due to any abnormality, the atmosphericpressure supply space 1402 can temporarily store thereleased ink, and can reliably recover it to theabsorber. Thus, an efficient cartridge can beprovided.

Fig. 4 shows an arrangement of the unit IJUmounting surface of the ink tank IT. If a straightline which passes almost the center of a projectingport of theorifice plate 400 and is parallel to thebottom surface of the tank IT or the mounting referencesurface for the surface of the carriage is representedby L₁, the twopositioning projections 1012 to beengaged with theholes 312 of thesupport member 300are located on the straight line L₁. The height ofeachprojection 1012 is slightly smaller than thethickness of thesupport member 300, and thisprojection positions thesupport member 300. Apawl2100 to be engaged with a 90° engagingsurface 4002 ofapositioning hook 4001 of the carriage is located onthe extending line of the straight line L₁ on thisdrawing, so that a positioning force for the carriageacts on a surface region parallel to the reference surface including the straight line L₁. As will bedescribed later with reference to Fig. 5, theserelationships are effective since the positioningprecision of only the ink tank is equivalent to that ofa discharge port of the head.

Projections 1800 and 1801 of the ink tankcorresponding to the fixingholes 1900 and 2000 of thesupport member 300 to the side surface of the ink tankare longer than the above-mentionedprojections 1012,and extend through thesupport member 300. Theprojecting portions of these projections are thermallyfused to fix thesupport member 300 on the side surfaceof the ink tank. When a straight line perpendicular tothe above-mentioned line L₁ and passing theprojection1800 is represented by L₃ and a straight line passingthrough theprojection 1801 is represented by L₂, sincealmost the center of thesupply port 1200 is located onthe straight line L₃, the above-mentioned projectionsstabilize a coupling state between thesupply port 1200and thesupply pipe 2200, and can reduce a load causedby dropping or a shock to the coupling state, resultingin a preferable arrangement.

The straight lines L₂ and L₃ do not coincide witheach other, and theprojections 1800 and 1801 arepresent around theprojections 1012 on the dischargeport side of the head IJH, thus reinforcing apositioning effect of the head IJH with respect to the tank. Note that a curve indicated by L₄ represents anouter wall position when theink supply number 600 ismounted. Since theprojections 1800 and 1801 arepresent along the curve L₄, they can provide asufficient mechanical strength and position precisionagainst to the weight of the arrangement on the distalend side of the head IJH. Note that adistal endcollar 2700 of the ink tank IT is inserted in a hole ofafront plate 4000 of the carriage HC to cope with anabnormal state wherein the ink tank is extraordinarilydisplaced. Aremoval stopper 2101 for the carriage HCis arranged near a bar (not shown) of the carriage HC,and serves as a projection member which is insertedbelow this bar at a position where the cartridge IJC isturned and mounted, as will be described later, andmaintains a mounting state even when an upward forcefor releasing the carriage from the aligned positionaccidentally acts.

The ink tank IT is covered with thelid member 800after the unit IJU is mounted thereon, thus defining ashape for surrounding the unit IJU excluding a loweropening. As for the ink-jet cartridge IJC, since alower opening to be mounted on the carriage HC isadjacent to the carriage HC, a substantially four-waysurrounded space is formed. Therefore, heat generatedby the head IJH located in the surrounded space iseffective for keeping a temperature in this space but corresponds to a small temperature increase when theapparatus is continuously used for a long period oftime. For this reason, in order to assist natural heatdissipation of the support member, aslit 1700 having asmaller width than this space is formed, so that auniform temperature distribution of the entire unit IJUdoes not depend on an environment while preventing atemperature increase.

When the ink-jet cartridge IJC is assembled, anink is supplied from the interior of the cartridge intothesupply member 600 via thesupply port 1200, thehole 320 formed on thesupport member 300, and an inletport formed on the central rear surface of thesupplymember 600. After the ink passes through the interiorof thesupply member 600, it flows into the common inkchamber via an appropriate supply pipe and theinkreception port 1500 of thetop plate 1300. Packingsof, e.g., silicone rubber or butyl rubber are arrangedin connected portions for ink communication in theabove arrangement, thus providing a seal to assure anink supply path.

In this embodiment, the top plate is formed of aresin such as polysulfone, polyethersulfone,polyphenylene oxide, polypropylene, or the like, and issimultaneously molded by molds together with theorifice plate portion 400.

As described above, since the integrally molded parts are theink supply member 600, an integratednumber of thetop plate 1300 and theorifice plate 400,and the ink tankmain body 1000, high assemblyprecision can be attained, and quality inmass-production can be improved. Since the number ofparts can be decreased, excellent predeterminedcharacteristics can be reliably exhibited.

In this embodiment, in an assembled shape, asshown in Figs. 2 to 4, a slit S is formed between anupper surface portion 603 of theink supply member 600and anend portion 4008 of a roof portion having theslit 1700 of the ink tank IT, as shown in Fig. 3, and aslit similar to the slit S is formed between alowersurface portion 604 and ahead end portion 4011 of athin plate member to which thelower lid member 800 ofthe ink tank IT is adhered. These slits between theink tank IT and theink supply member 600 essentiallyperform an operation for promoting heat radiation oftheslit 1700, and can prevent an unnecessary pressureapplied to the tank IT from directly applying to thesupply member, and the ink-jet unit IJU.

In any case, the above arrangements of thisembodiment are unique ones, can independently provideadvantages, and can also provide a systematicarrangement as a whole.

(iii) Mounting of Ink-jet Cartridge IJC to Carriage HC

In Fig. 5, aplaten roller 5000 guides a recording medium P from a lower side of the drawing toward anupper side. The carriage HC is moved along theplatenroller 5000, and is provided with the front plate 4000(thickness = 2 mm) located on the front surface side ofthe ink-jet cartridge IJC on the side of the frontplaten of the carriage, an electrical connectingportion support plate 4003 for holding aflexible sheet4005 comprisingpads 2011 corresponding to thepads 201of thewiring circuit board 200 of the cartridge IJCand arubber pad sheet 4007 for generating an elasticforce for pressing thesheet 4005 against thepads 2011from the rear surface side, and thepositioning hook4001 for fixing the ink-jet cartridge IJC to therecording position. Thefront plate 4000 has twopositioning projection surfaces 4010 corresponding tothe above-mentionedpositioning projections 2500 and2600 of thesupport member 300 of the cartridge. Afterthe cartridge is mounted, the front plate receives aforce perpendicular to the projection surfaces 4010.For this reason, a plurality of reinforcement ribs (notshown) along the direction of the force are arranged onthefront plate 4000 on the side of the platen roller.These ribs also form head protection projectionsslightly projecting (about 0.1 mm) from a front surfaceposition L₅ of the cartridge IJC when the cartridge IJCis mounted.

The electrical connecting portion support plate 4003 has a plurality ofreinforcement ribs 4004 not ina direction of the above-mentioned ribs but in adirection perpendicular thereto. A sideward projectingamount is decreased from the platen side toward thehook 4001. This also serves to provide a function ofinclining the cartridge mounting position, as shown inFig. 5.

The support plate 4003 has two hook-sideprojection surfaces 4006 for applying a force to thecartridge in a direction opposite to a direction of aforce applied from the twopositioning projectionsurfaces 4010 to the cartridge to form a pad contactregion between these two positioning surfaces, and touniquely define deformation amounts of projections oftherubber pad sheet 4007, which projections correspondto thepads 2011. These positioning surfaces are incontact with the surface of thewiring circuit board200 when the cartridge IJC is fixed at a recordingposition. In this embodiment, since thepads 201 ofthewiring circuit board 200 are distributed to besymmetrical about the above-mentioned line L₁, thedeformation amounts of the projections of therubberpad sheet 4007 can be uniformed to much stabilizecontact pressures of thepads 2011. In thisembodiment, thepads 201 are distributed in a 2 x 2matrix.

Thehook 4001 has an elongated hole to be engaged with astationary shaft 4009. Thehook 4001 is pivotedcounterclockwise from the illustrated position byutilizing a moving space of this elongated hole, andthereafter, is moved to the left along theplatenroller 5000, thereby positioning the ink-jet cartridgeIJC with respect to the carriage HC. Thehook 4001 maybe moved in any other patterns, but may be preferablymoved by, e.g., a lever. When thehook 4001 ispivoted, the cartridge IJC is moved toward the platenroller, and thepositioning projections 2500 and 2600are moved to positions where they can be brought intocontact with thepositioning surfaces 4010 of the frontplate. When thehook 4001 is moved to the left, the90° engagingsurface 4002 is brought into tight contactwith the 90° surface of thepawl 2100 of the cartridgeIJC, and the cartridge IJC is turned about the contactregions between thepositioning surfaces 2500 and 4010in the horizontal plane as the center. Finally, thepads 201 and 2011 begin to be brought into contact witheach other. When thehook 4001 is held at apredetermined position, i.e., a fixing position, acomplete contact state between thepads 201 and 2011, acomplete surface contact state between thepositioningsurfaces 2500 and 4010, a two-surface contact statebetween the 90° engagingsurface 4002 and the 90°surface of the pawl, and a surface contact statebetween thewiring circuit board 200 and thepositioning surfaces 4007 and 4008 are simultaneouslyformed, thus completing holding of the cartridge IJCwith respect to the carriage HC.

(iv) Apparatus Main Body

Fig. 6 is a schematic perspective view of theink-jet recording apparatus main body IJRA on which theabove-mentioned cartridge is mounted. The carriage HCwhich is engaged with aspiral groove 5004 of aleadscrew 5005 rotated through driving force transmissiongears 5011 and 5009 in cooperation with aforward/reverse rotation of a drivingmotor 5013 haspins (not shown), and is reciprocally moved indirections of arrowsa andb. Asheet pressing plate5002 presses a sheet against theplaten roller 5000along the carriage moving direction.Photocouplers5007 and 5008 serve as home position detection meansfor detecting the presence of alever 5006 of thecarriage HC in a corresponding region to switch, e.g.,a rotational direction of themotor 5013. Amember5016 supports acap member 5022 for capping the frontsurface of the recording head. A suction means 5015draws the interior of this cap member by vacuumsuction, i.e., performs a suction/recovery operation ofthe recording head through anopening 5023 in the capmember. Acleaning blade 5017 and amember 5019 forallowing theblade 5017 to be movable in theback-and-forth direction are supported on a mainbody support plate 5018. The blade is not limited to thatof this embodiment, but a known cleaning blade may beapplied to this embodiment, as a matter of course. Alever 5021 is used to start the suction/recoveryoperation, and is moved upon movement of acam 5020which is engaged with the carriage HC. Thelever 5021is subjected to movement control by a knowntransmission means such as a clutch for switching adriving force from the driving motor.

These capping, cleaning, and suction/recoveryoperations can be performed at their correspondingpositions upon operation of thelead screw 5005 whenthe carriage HC reaches the home position region.However, any other means may be applied to thisembodiment as long as desired operations are performedat known timings. The respective arrangementsdescribed above are excellent inventions not onlysolely but also systematically, and are preferable onesto apply the present invention.

The present invention which can be applied to thearrangements shown in Figs. 2 to 6 will be describedbelow with reference to Fig. 1, Fig. 7, and subsequentdrawings.

Figs. 1, 7, and 15, and Tables 1 and 2 show thefirst embodiment of the present invention. In Fig. 1,a recording head 2 (IJH) is coupled to an ink tank 1(IT). As shown in Fig. 7, theink tank 1 and therecording head 2 form an integrated disposablecartridge. A carriage 3 (HC) is used to mount thecartridge on the printer main body. Aguide 4 scansthe carriage in a sub-scanning direction. Aflexiblecable 6 supplies a driving signal pulse current and ahead temperature control current to therecording head2. A printedcircuit board 7 comprises an electricalcircuit for controlling the printer. Asensor 8measures an ambient temperature in the printer. Fig. 7shows the disposable cartridge. In Fig. 7, anozzleportion 7 discharges ink droplets.

Fig. 8 shows therecording head 2 in detail. Theheater board 100 formed by a semiconductormanufacturing process is arranged on the upper surfaceof thesupport member 300. Theheater board 100comprises a temperature control heater (temperatureincrease heater) 10 for keeping and controlling thetemperature of therecording head 2. Thewiringcircuit board 200 is arranged on thesupport member300. Thewiring circuit board 200, thetemperaturecontrol heater 10, and adischarge heater 13 areelectrically connected by, e.g., wire-bonding (wiringsare not shown). Thetemperature control heater 10 maybe formed by adhering a heater member, which is formedin a process different from that for theheater board100, to, e.g., thesupport member 300, as shown inFig. 9.

Abubble 14 is formed upon heating of thedischarge heater 13. Thebubble 14 is then dischargedas anink droplet 15. Acommon ink chamber 12 suppliesan ink to be discharged into the recording head.

Open-loop temperature control according to thefirst embodiment will be briefly described below.

In this embodiment, in order to control thetemperature of the recording head to a targettemperature determined by concerning dischargecharacteristics, e.g., a print density, temperaturecontrol before printing and temperature control duringprinting are performed. In the temperature controlbefore printing, a heating amount of the temperaturecontrol heater is determined on the basis of a lapse oftime from the previous printing operation (wait timeand non-print time) and the present ambienttemperature, and heating is performed immediatelybefore printing. In the temperature control duringprinting, the heating amount is determined on the basisof the lapse of time from the previous printingoperation and the present ambient temperature, andheating is performed during printing. "Duringprinting" means not only an instance when printing isactually performed (a heating period of a printheater), but also a series of operation periods forperforming printing, e.g., an acceleration ordeceleration period of the carriage, and a reverse period in a bidirectional print mode.

Temperature Control Data Table Before Printing
Ambient Temperature	25°C or higher	25 to 21°C	21 to 17°C	17 to 13°C	13°C orlower
Wait Time
0 or 120 sec or more	0%	40%	60%	80%	100%
60 to 120sec	0%	10%	40%	60%	80%
30 to 60sec	0%	0%	20%	40%	60%
15 to 30sec	0%	0%	0%	20%	40%
15 sec or less	0%	0%	0%	0%	20%

Temperature Control Data Table DuringPrinting
Ambient Temperature
	25°C or higher	25 to 21°C	21 to 17°C	17 to 13°C	13°C orlower
Print Time
0 to 60sec	0%	60%	80%	90%	100%
60 to 360sec	0%	30%	40%	45%	50%
360 sec or more	0%	20%	30%	35%	40%

Tables 1 and 2 show control parameter data tablesused when the temperature control operations before andduring printing are performed, and these tables arestored in a ROM. In each table, "100%" representssupply of a maximum energy, and "0%" represents supplyof no energy. In this embodiment, an energy supplyamount is controlled according to an energization time(heating pulse width) to the temperature controlheater. In the temperature control before printing, amaximum energization time is set to be about 6 sec, andin the temperature control during printing, it is setto be about 120 msec. Note that the energy supplyamount may be controlled by an energization voltage in place of the energization time, or may be controlled byboth the energization time and voltage.

In either of the temperature control operationsbefore and during printing, as an ambient temperatureis lower, the energy supply amount is increased toincrease a temperature increase amount, so that thehead temperature is closer to the target temperature.In the temperature control before printing, since itcan be considered that the recording head radiates moreheat as a wait time is longer, the energy supply amountis set to be large to cause the head temperature toapproach the target temperature. On the other hand, inthe temperature control during printing, since it canbe considered that the temperature of the head isincreased due to heat accumulation as a print time islonger, the energy supply amount is set to be small.

When the temperature control is performed asdescribed above, the temperature of the recording headcan be controlled to the target temperature withoutusing conventional closed-loop control. Thistemperature control will be described in detail below.

Fig. 10 shows a change in actual temperature (T_H)of the recording head with respect to an ambienttemperature (T_A) and a target temperature (T₀) whenonly the temperature control before printing isperformed. Fig. 11 similarly shows a change intemperature of the recording head when only the temperature control during printing is performed, and

Fig. 12 shows a change in temperature of the recordinghead when both the temperature control operationsbefore and during printing are performed.

Fig. 13 shows a change in temperature of therecording head caused by printing itself (selftemperature increase) when only printing is performedwithout the temperature control.

Fig. 14 shows a change in temperature of therecording head when printing is performed with thetemperature control operations before and duringprinting.

The temperature (T_H) of the recording head isswitched at positions of 60 sec and 360 sec since thedata in the temperature control data table duringprinting shown in Table 2 (temperature controlparameter) is changed.

A thermal equilibrated temperature (T_E) shown inFigs. 11 and 12 means a temperature which can benaturally reached by only a temperature control energyon the basis of a heat capacity of the head, and isdetermined by data shown in Tables 1 and 2. Thethermal equilibrated temperature is set to be slightlylower than the target temperature, so that the sum ofthe thermal equilibrated temperature and a temperatureincrease (self temperature increase) caused by selfheating of the recording head shown in Fig. 13 corresponds to the target temperature.

The temperature control according to the firstembodiment of the present invention will be describedbelow with reference to the flow chart shown inFig. 15. Note that a change in temperature of therecording head caused by this temperature controlcorresponds to Fig. 14.

When the power switch is turned on, a wait timecounter and a print time counter are reset to zero toinitialize the control parameters in step S101. Instep S102, the control waits until a print signal isinput.

When the print signal is input, an ambienttemperature is read from thetemperature sensor 8 onthe printedcircuit board 7 of the main body in stepS103. In step S104, a wait time of the wait timecounter is read. However, the wait time counter isreset to "0" as described above immediately afterpower-on. In step S105, the temperature control datatable before printing (Table 1) is referred to on thebasis of the ambient temperature and the wait time ofthe wait time counter. Immediately after power-on,since there is no temperature increase due to printing,the temperature of the recording head is equal to theroom temperature. For this reason, a table outputbecomes one of 0% to 100% according to the ambienttemperature, and is larger than those obtained in correspondence with other wait times. In step S106,thetemperature control heater 10 shown in Fig. 8 isheated on the basis of this output data to increase thetemperature of thenozzle portion 9 and thecommon inkchamber 12. In this embodiment, as the ambienttemperature is lower, the table output is increased toincrease a temperature increase amount.

Upon completion of energization, the start ofprinting may be waited for about 1 sec to disperse anabrupt temperature distribution formed in the recordinghead. At that time, the wait time counter is reset(step S107).

In step S108, the print time counter is started toprint the first line (step S109).

Thereafter, in step S110, the print time of theprint time counter is read. In step S111, thetemperature control data table during printing (Table2) is referred to on the basis of the read print timeand the ambient temperature. The count value of theprint time counter is not so incremented immediatelyafter the start of printing, either. For this reason,the table output becomes one of 0% to 100% according tothe ambient temperature, and is larger than thoseobtained in correspondence with other count values.

Temperature control conditions of the data arecorrected according to the content of the print signal.When a line feed (LF) signal is input, correction is performed (steps S112 and S113). Since the line feedoperation has no temperature increase due to printingitself, if the LF signals are successively input, thetemperature of the recording head is immediatelydecreased if no temperature control is performed.Since a time required for the line feed operation isvery short, an energy supply amount per unit timebecomes too large unless the output data is corrected.

For this reason, according to this embodiment, aprogram for correcting a parameter to supply anenergy1/10 original output data to the recording head perone-line feed operation is employed.

The temperature control conditions are thencorrected on the basis of a length of one main scanningline (steps S114 and S115). In this embodiment, thetemperature control heater 10 is energized duringcarriage acceleration periods on two sides outside aprint range. For this reason, when a carriage movingamount is small, an energy supply amount per unit timebecomes too large. When the carriage mounting amountdoes not correspond to a full width, a problem formultiplying a correction coefficient proportional to anactual moving amount corresponding to the full widthwith the parameter is employed.

Thetemperature control heater 10 is energized onthe basis of these corrected data to performtemperature control during printing (step S116), and another line is then printed (step S117). When theprint operation further continues (step S118), thevalue of the print time counter is repetitively read.As described above, as the print time is increased, theoutput data from the table is decreased. Thus, theenergy supply amount is decreased.

When the print operation is completed, the printtime counter is reset (step S119), and the wait timecounter is started (step S120) to measure a time untilthe next print signal is input.

When the next print signal is input, the contentsof the wait time counter and the ambient temperatureare read (steps S102 to S104), and an energy leveloutput from the temperature control data table beforeprinting is determined again on the basis of the readwait time and the ambient temperature. Thereafter, thesame control operations as described above arerepeated. In this embodiment, the wait time countercounts up to 120 sec, and when it exceeds 120 sec, thecounter is reset to 0 under the assumption that thetemperature is returned to the ambient temperature.

In this embodiment, the disposable cartridge typerecording head is used. The present invention is notlimited to the disposable cartridge type, but may beeffective when it is applied to a permanent type headwhich does not require exchange of heads.

In this embodiment, both the print time counter and the wait (non-print) time counter are used toperform both the temperature control operations duringand before printing. However, as for a printer havinga small print amount such as a printer for anelectronic calculator, or a printer for outputting onlycharacters, in which a temperature increase caused bythe print operation itself is smaller than that causedby a graphic printer, only the wait (non-print) timecounter may be employed depending on an output qualitylevel of the recording apparatus to perform only thetemperature control before printing. As for a printerexclusively used for cut sheets or a recordingapparatus having a long non-print time, only the printtime counter may be employed to perform only thetemperature control during printing.

In order to determine an output energy level intemperature control, a hysteresis of output dataobtained before printing may be used in addition tooutput data obtained by referring to the data table onthe basis of the count values (wait time and printtime) upon printing. When a correction coefficient ofoutput data is to be calculated on the basis of acarriage moving amount, not only a moving amount of thepresent line but also moving amounts of the next andsubsequent lines may be taken into consideration.

As a means for heating the recording head, a knownmeans may be used. In place of measuring the print time, the number of print lines or the number of printcharacters may be counted.

As described above, according to the firstembodiment, if conventional closed-loop temperaturecontrol by the temperature sensor incorporated in therecording head is not performed, a means for measuringan ambient temperature is arranged in a recordingapparatus main body such as a printer, and a controlsoftware program utilizing heating/cooling thermalcharacteristics uniquely determined by a heat capacityof the recording head itself is employed, so that thetemperature of the recording head can be controlled toa desired temperature.

In particular, when the disposable cartridge typerecording head is used, a signal current from thetemperature sensor of the recording head need not bedetected. Thus, a variation in print performance amongheads, as a major drawback of temperature control posedwhen the disposable type is employed, can beeliminated. Thus, a variation in print performanceamong heads can be eliminated, and uniform printquality can be obtained. Furthermore, since thetemperature sensor can be omitted from the cartridge ofthe recording head as an expendable supply, atemperature sensor selection process, or a temperaturesensor adjustment process so far can be omitted togreatly reduce cost. In addition, since the temperature sensor itself can be omitted, amanufacturing yield can be greatly increased to furtherreduce cost.

In view of an electrical circuit, a small signalcurrent from the head need not be detected, and acountermeasure against exposure of contacts uponattachment/detachment of the disposable cartridge fromthe recording apparatus main body, and an electrostaticcountermeasure for patterns of a flexible wiring and aprinted circuit board between the recording apparatusmain body and the recording head can be simplified.

The above features are particularly effective fora compact or portable recording apparatus which cannottake a sufficient countermeasure such as a shield onthe casing or an electrical circuit. In addition, thisalso leads to a considerable cost-down effect.

The second embodiment of the present inventionwill be described below with reference to Figs. 17 to21 and Tables 3 and 4.

In the second embodiment, sufficient temperaturecontrol attained by developing open-loop control of thefirst embodiment can be performed even in a recordingmethod such as a bubble-jet method in which heatgeneration or radiation occurs upon printing.

In the first embodiment, an energy level to beapplied to the recording head for attaining atemperature increase is determined with reference to control data tables on the basis of an ambienttemperature and a print time and a non-print time ofthe recording head before the present print operationis started, so that temperature control can be realizedby open-loop control by using only an adjustedtemperature sensor of a main body.

In a printer for mainly printing characters, sincea print rate of a character itself is low, an averageprint rate is about several % to 30%. Therefore, atemperature can be sufficiently anticipated byopen-loop temperature control on the basis of dataanticipated by the main body according to operationcontrol parameters such as a print time and a non-printtime which can be easily measured by the printer likein the first embodiment, and a temperature controlenergy supply amount can be adjusted.

However, in a printer for mainly printing graphicdata at high speed, since an average print rate islargely changed between several % to 100%, an over heatstate tends to occur, as shown in Fig. 16, by onlyoperation control parameters such as a print time and anon-print time when a temperature control energy and aheat generation energy caused by a discharge operationat a high print rate overlap each other. For thisreason, irregular discharge problems such as anon-discharge state, splash, a fixing error caused byan excessive discharge amount, density nonuniformity, and the like are posed, and a graphic printer which isrequired to have high print quality becomesunsatisfactory.

In order to prevent an overhead state caused by ahigh print rate, a thermal equilibrated temperature maybe set to be lower than that of a character printerunder an assumption of a high average print rate. Atthis time, when a print pattern having a low print rateis to be printed, since a self temperature increase issmall in the above-mentioned open-loop temperaturecontrol during printing, the actual temperature of therecording head is shifted to a lower temperature, andlow density or density nonuniformity occurs. Thus,only an unsatisfactory print result is obtained by ahigh-speed graphic printer.

During a print operation of a graphic patternhaving a high print rate, when a temperature at the endof the first page becomes very high, and in particular,when the print operation of the page is completedimmediately before the temperature reaches an over heattemperature, a cooling operation requires more timethan that at an assumed average print rate. For thisreason, in the open-loop temperature control beforeprinting, a temperature increase energy excessivelylarger than that required for the next print operationmay be undesirably supplied.

Open-loop temperature control according to the second embodiment will be briefly described below.

In this embodiment, temperature control operationsbefore and during printing are performed like in thefirst embodiment. At this time, according to acharacteristic feature of this embodiment, atemperature of the recording head is anticipated uponcompletion of the previous print operation, and atemperature control power before printing is correctedon the basis of the anticipated temperature.Furthermore, according to another characteristicfeature of this embodiment, a print rate is obtainedevery second, and a temperature control power duringprinting is corrected on the basis of an average printrate. When the above-mentioned power correctionoperations are performed, open-loop temperature controlcan be appropriately performed in a graphic printerwhich must print a pattern having a high print rate.

Tables 3 to 5 respectively show temperaturecontrol data tables before and during printing, and aprint rate correction control parameter data table.Tables 3 and 4 correspond to Tables 1 and 2 of thefirst embodiment, respectively.

Temperature Control Data Table Before Printing
Ambient Temperature	25°C or higher	25 to 21°C	21 to 17°C	17 to 13°C	13°C or lower
Wait Time Timer
0 or 120 sec or more	0%	40%	60%	80%	100%
60 to 120sec	0%	10%	40%	60%	80%
30 to 60sec	0%	0%	20%	40%	60%
15 to 30sec	0%	0%	0%	20%	40%
15 sec or less	0%	0%	0%	0%	0%

Temperature Control Data Table DuringPrinting
Ambient Temperature
	25°C or Higher	25 to 21°C	21 to 17°C	17 to 13°C	13°C or lower
Initial Operation Amount PLINEO of Temperature Control During Printing	0%	60%	80%	90%	100%

Duty CorrectionData Table
Duty
	0% or more	6.25% or more	12.5% or more	25% or more	50% ormore
Correction Coefficient
	100%	87.5%	75%	50%	0%

Fig. 17 shows a change in actual temperature ofthe recording head with respect to an ambienttemperature and a target temperature when onlytemperature control during printing (withoutcorrection) is performed. Note that a change intemperature of the recording head obtained when onlythe temperature control before printing (withoutcorrection) is performed is the same as that shown inFig. 10, and is omitted. Fig. 18 similarly shows a change in temperature of the recording head when boththe temperature control operations before and duringprinting (without correction) are performed.

Fig. 19A shows a change in print rate, Fig. 19Bshows a change in temperature of the recording head incorrespondence with a change in print rate shown inFig. 19A when the temperature control operations beforeand during printing according to the second embodimentof the present invention are performed, and Fig. 19Cshows a change in operation amount of a temperaturecontrol energy.

A thermal equilibrated temperature shown inFigs. 17 and 18 is set to be higher than those shown inFigs. 11 and 12. The first embodiment takes selfheating of the recording head into consideration whenthe thermal equilibrated temperature is set. In thisembodiment, however, since a self heating portion iscorrected in the temperature control during printing,the self heating portion need not be taken intoconsideration when the thermal equilibrated temperatureis set.

For this reason, an energy supply amount of thetemperature control during printing according to thisembodiment is slightly larger than that in the firstembodiment.

Temperature control according to the secondembodiment of the present invention will be described below with reference to the flow chart shown inFig. 20. Note that a change in temperature of therecording head by this temperature control correspondsto Fig. 19.

When the power switch is turned on, a wait timecounter, a print time counter, a print pulse counter, acorrection coefficient memory, and the like are resetto "0" (step S201) to initialize control parameters.The control then waits until a print signal is input(step S202).

When the print signal is input, an ambienttemperature T obtained by thetemperature sensor 8 onthe printedcircuit board 7 of the main body is read(step S203). An anticipated temperature T_FINI uponcompletion of the previous print operation (to bedescribed in detail later) is then read (step S204). Await time tw is then read from the wait time counter (step S205).At this time, the counter is reset to "0" as describedabove. The temperature control data tables before andduring printing (Tables 3 and 4) are referred to on thebasis of the wait time tw and the ambient temperature(step S206). At this time, since there is notemperature increase caused by the print operation andan ambient temperature is the same as the roomtemperature, output data as a determination value ofthe temperature control power P_preo table beforeprinting becomes one of 0 to 100% according to the ambient temperature, and has a larger value than thoseobtained in correspondence with other wait times (stepS206).

On the basis of this output data, a temperaturecontrol operation amountPpre before printing = Ppreo xf(TFINI) is calculated (step S207). The functionf hasa negative correlation with the anticipated temperatureT_FINI upon completion of the previous print operation.Thetemperature control heater 10 shown in Fig. 8 isheated on the basis of the calculated operation amountP_pre, and the temperatures of thenozzle portion 9 andthecommon ink chamber 12 of therecording head 2 areincreased (step S208). In this embodiment, anenergization time is prolonged as a temperature becomeslower. After completion of energization, a print starttiming is waited for about 1 sec to disperse an abrupttemperature distribution formed in the recording head.At that time, the wait time counter is reset (stepS209), and the print time counter is started (stepS210).

Temperature control conditions of the initialoperation amount P_LINEO during printing obtained instep S206 are then corrected according to the contentof the print signal. The temperature controlconditions are corrected according to the length of onesub-scanning line. Like in steps S114 and S115(Fig. 15) in the first embodiment, a power correction coefficient L for multiplying a correction coefficientproportional to a ratio of an actual moving amount tothe full width of the carriage is calculated (stepS211).

Discharge pulses for one second (number of printdots) of the next print content to be printed arecounted to calculate an average print rate (print duty)(step S212).

Power correction coefficients P₁ and P₂ arecalculated on the basis of the average print rate forevery second (step S213). In this case, the powercorrection coefficient P₁ is a low-response correctioncoefficient, and is based on an average of averageprint rates for every seconds during previous 100seconds. The power correction coefficient P₂ is ahigh-response correction coefficient, and is based onan average of average print rates for every secondduring previous 10 seconds. These correctioncoefficients P₁ and P₂ can be obtained by referring tothe data table (Table 5) on the basis of the averageprint rate.

A temperature control operation amount P_LINEduring printing is calculated on the basis of theobtained data.

In this embodiment,PLINE = PLINEO x P1 x P2 x L(step S214).

As described above, P_LINEO represents the temperature control initial operation amount duringprinting, and the correction coefficient L is one basedon the carriage moving amount. The correctioncoefficient is normalized to a range between 0 to 1 (0%to 100%). As can be apparent from the above equation,when the low- or high-response average print rate ishigh, and its correction coefficient P₁ or P₂ is small,the temperature control operation amount P_LINE duringprinting becomes small. Therefore, an over heat stateby the temperature control during printing can beprevented.

For this reason, a program for correcting aparameter to supply anenergy 1/10 the originaloperation amount P_LINE during printing to therecordinghead 2 per one-line feed operation is employed (stepS216).

Thetemperature control heater 10 is energized onthe basis of these corrected data (step S217) to printone line (step S218). The wait time counter is thenstarted (step S219), and the anticipated temperatureT_FINI upon completion of printing is stored (stepS220). The anticipated temperature T_FINI uponcompletion of printing is calculated by the followingequation based on a parameter of the power correctioncoefficient P₁ (low response):TFINI = Target Temperature x k(0.3 + P1)   (wherek is an appropriate coefficient)

When(0.3 + P1) < 1, TFINI = target temperature isset. As a result, when the low-response powercorrection coefficient exceeds 0.7, this means that aprint operation at a high print rate continues for along period of time, and there is a high possibilitythat the head temperature exceeds the targettemperature. For this reason, an error of thetemperature control power P_preo before printingcalculated based on the wait time at the beginning ofthe next print operation can be prevented.

When the print operation continues, the controloperations shown in Fig. 20 are repeated. In thiscase, since the value of the wait time counter is notso incremented, an output of 0% is obtained at anyambient temperature, and temperature control beforeprinting can be prevented from being performed for eachline. When the print operation is completed (stepS221), the print time counter is reset (step S222), andthe control operations shown in Fig. 20 are repeatedwhen the next print signal is input.

In this embodiment, the wait time counter alsocounts up to 120 sec, and when it exceeds 120 sec, thecounter is reset to 0 under the assumption that thetemperature is returned to the ambient temperature.

Fig. 21 is a block diagram showing a controlarrangement for executing temperature control accordingto the second embodiment. This arrangement can be applied to the first embodiment.

In Fig. 21, ahost 21 such as a computer generatesa command signal, a print signal, and the like. Acounter 21 serves as a counting means consisting of thewait time counter, the print time counter, the printpulse counter, and the like. Asensor 8 serves as atemperature measurement means for measuring an ambienttemperature. A head driving means 25 drives therecording head 2, and heats the head to increase itstemperature. Acontrol unit 22 as a temperaturecontrol means controls the print operation of a normalink-jet recording apparatus according to a programstored in the ROM (read-only memory) 24. Thecontrolunit 22 adjusts a temperature control energy forattaining a temperature increase applied to therecording head 2 by the head driving means 25 on thebasis of the measurement results of the sensor 23 andthecounter 21.

In this embodiment, both the temperature controloperations during and before printing are performedusing both the print time counter and the wait(non-print) time counter. However, as for a printerexclusively used for cut sheets or a recordingapparatus having a long non-print time, only the printtime counter may be employed to execute only thetemperature control during printing.

In place of measuring the print time, the number of print lines or the number of print characters may becounted. An average print rate per second may becalculated as one for each line. The average rate maybe calculated by other averaging methods, e.g.,weighting.

A low-response print rate may be calculated as anaverage of average print rates for every 10 secondsduring previous 100 seconds. In this embodiment, acommon correction data table (Table 5) is used for low-andhigh-response data, but different tables may beprepared.

The temperature control operation amount P_prebefore printing may be corrected using the correctioncoefficients P₁ and P₂ in place of using the functionf(T_FINE).

According to the second embodiment as describedabove, since a temperature control power is controlledaccording to a print rate, high-precision temperaturecontrol can be attained in a graphic printer having alarge change in print rate in addition to the effectsof the first embodiment.

Since a temperature control power is controlled onthe basis of low- and high-response print rates, thecontrol can cope with both slow and abrupt changes inprint rate.

In the second embodiment, the temperature controlpower is controlled on the basis of the low- and high-response print rates, but may be controlled one ofthese parameters. Furthermore, a middle-response printrate may be calculated to control the temperaturecontrol power on the basis of the low-, middle-, andhigh-response print rates.

The third embodiment of the present invention willbe described below with reference to Figs. 22 to 26 andTable 6.

In the third embodiment, high-precisiontemperature control can be performed even when aposition of a recording head is physically separatedfrom a position of a temperature sensor for measuringan ambient temperature.

In the first embodiment of the present inventiondescribed previously, the temperature sensor formeasuring an ambient temperature is arranged not on arecording head unit but on an apparatus main body onwhich the recording head unit is mounted, and ananticipated control method is adopted wherein atemperature of the recording head is anticipated on thebasis of a thermal time constant determined based on aheat capacity of the recording head, a print time, anda non-print time to control a temperature controlamount.

According to this method, since the recording headdoes not have a temperature sensor, cost of therecording head as an expendable supply can be greatly reduced, and this can provide a considerably largemerit in, especially, a disposable cartridge in whichthe recording head and an ink tank are integrated.

In the first embodiment, however, since theposition of the recording head is physically separatedfrom the position of the temperature sensor formeasuring an ambient temperature, a temperaturedetected by the temperature sensor cannot oftenindicate a correct temperature at the position of therecording head. When a power supply circuit isincorporated in the apparatus, a temperature in themachine is increased due to heat generated by the powersupply circuit. In this case, an increase intemperature in the machine varies depending onpositions in the machine. Since the temperature sensorand the recording head have quite different orders ofthermal time constant, even if the ambient temperaturesensor and the recording head have the same temperaturein the machine, a small error occurs between thetemperature at the position of the recording head andthe ambient temperature of the ambient temperaturesensor before a lapse of a given time after power-onalthough these temperatures are finally equal to eachother after the lapse of the given time. For thisreason, in the first embodiment, a temperature controlparameter for anticipated control is often determinedon the basis of the temperature data including an error. Even if the identical apparatus and theidentical recording head are used, a print density ofprints may often be varied.

Open-loop temperature control according to thethird embodiment will be described below. In thiscontrol, a temperature control parameter determined byparameters such as an ambient temperature, a printtime, a non-print time, and the like is correctedaccording to an energization time of the apparatus mainbody or components in the machine which generate heat,so that a local difference in temperature increase inthe machine, or an error in an anticipated temperatureof the recording head caused by a time difference dueto a difference in thermal time constant are corrected,thus attaining precise temperature control.

Fig. 22 shows a temperature increase in themachine near the temperature sensor for measuring anambient temperature, and an actual temperature of therecording head at that time. Fig. 22 exemplifies datawhen a heat generation portion is separated from therecording head unit, and the recording head unit doesnot suffer from a temperature increase in the machine.

Fig. 23 shows an ambient temperature near thetemperature sensor for measuring the ambienttemperature, and an actual temperature of the recordingheat at that time. Fig. 23 exemplifies data when therecording head unit suffers from a temperature increase in the machine.

Note that basic data of a change in actualtemperature of the recording head with respect to theambient temperature and the target temperature obtainedwhen only the temperature control before printing isperformed in a state wherein there is no temperatureincrease in the machine near the recording head is thesame as that shown in Fig. 10, basic data similarlyobtained when only the temperature control duringprinting is performed is the same as that shown inFig. 11, and basic data obtained when the temperaturecontrol operations before and during printing areperformance is the same as that shown in Fig. 12. Inaddition, a change in temperature of the recording headobtained when only printing is performed withouttemperature control is the same as that shown inFig. 13.

Table 6 shows a correction table of a temperatureincrease in the machine in correspondence with Fig. 22.Note that above Tables 3 and 2 are used as temperaturecontrol data tables before and during printing.

Correction Data Table for TemperatureIncrease in Machine
Correction Timer for Temperature Increase inMachine	0 to 2min	2 to 5min	5 to 15min	15 to 30min	30 min ormore
Correction Value
	0°C	-2°C	-4°C	-6°C	-7°C

Temperature control according to the thirdembodiment of the present invention will be describedbelow with reference to the flow chart shown inFig. 24. Note that a change in temperature of therecording head caused by this temperature control isthe same as that shown in Fig. 14.

When the power switch is turned on, a wait timecounter, and a print time counter are reset to "0", anda correction timer for a temperature increase in themachine is started (step S301). In step S302, thecontrol waits until a print signal is input.

When the print signal is input, the print timecounter is started (step S303), and an ambienttemperature is read from thetemperature sensor 8 onthe printedcircuit 7 of the main body in step S304.In step S305, the value of the correction timer isread, and in step S306, the value of the ambienttemperature read in step S304 is corrected on the basisof the value of the correction timer. The correctionvalue is determined by the correction table for atemperature increase in the machine shown in Table 6.

The correction table as Table 6 corresponds to Fig. 22. In the case of Fig. 23, data obtained bysubtracting the temperature of the recording head unitfrom the temperature of the ambient temperature sensorunit may be input to the correction table.

In step S307, a wait time of the wait time counteris read. The wait time counter is reset to "0", asdescribed above, immediately after power-on. In stepS308, the temperature control data table (Table 3) isreferred to on the basis of the corrected ambienttemperature and the wait time of the wait time counter.In step S309, thetemperature control heater 10 shownin Fig. 8 is heated on the basis of this output data toincrease the temperatures of thenozzle portion 9 andthecommon ink chamber 12 of the recording head. Uponcompletion of energization, the wait time counter isreset (step S310).

In step S311, a print time of the print timecounter is read. The count value of the print timecounter is not so incremented just after the start ofthe print operation. In step S312, reference outputdata is determined with reference to the temperaturecontrol data table during printing (Table 2).

Temperature conditions of this data are correctedaccording to the content of the print signal (stepsS313 to S316). These steps are the same as steps S112to S115 in Fig. 15, and a detailed description thereofwill be omitted.

Thetemperature control heater 10 is energizedusing these corrected data to perform temperaturecontrol during printing (step S317), and one line isthen printed (step S318).

The wait time counter is started (step S319).When the print operation further continues, the printtime counter is repetitively read in step S311 via stepS320, and as the print time is increased, an energysupply amount is deceased on the basis of the data onthe temperature control data table during printing(Table 2). When the print operation continues, sincethe value of the wait time counter is not almostincremented, an output of 0% is obtained at any ambienttemperature, as shown in Table 3, temperature controlbefore printing can be prevented from being performedfor each line.

Once the print operation is completed, the printtime counter is reset (step S321), and the wait timecounter measures a time until the next print signal isinput.

When the next print signal is input, the values ofthe wait time counter, the ambient temperature, and thecorrection table for a temperature increase in themachine are read (step S304 to S307), an output energylevel is similarly determined again on the basis of thetemperature control data table before printing (stepS308), thus repeating the same control operations.

In the third embodiment, a program having a tablefor correcting a temperature of the sensor unit by adifference in temperature between the ambienttemperature sensor unit and the recording head unit isadopted. A temperature keeping current for correctinga temperature difference may be supplied to therecording head unit under the control of the correctiontable to attain the same temperature increase as thatof the ambient temperature sensor unit. With thisarrangement, the same effect as described above can beobtained.

Alternatively, when a temperature keeping currentis not corrected based on the correction table, a smalltemperature keeping current may be supplied to therecording head unit during an ON period of a powersupply, so that the recording head unit can havesubstantially the same temperature increase as that ofthe ambient temperature sensor unit. In this case, acurrent which is determined in correspondence with athermal time constant of temperature increasecharacteristics of the recording head depending on atime from power-on regardless of a software program issupplied to the recording head. This control isequivalent to temperature correction in correspondencewith a power-ON time. It is difficult more or less tocorrect the temperature of the recording head to bequite the same as the temperature increase of the ambient temperature sensor since the temperatureincrease of the ambient temperature sensor is attainedby complex factors such as convection of air, heattransmitted from the circuit board, heat generated bythe recording head itself, and the like. However, thiscontrol is satisfactory to correct a temperatureincrease in the machine.

In the above embodiment, heat generation accordingto a power-ON time is taken into consideration.Furthermore, heat generation according to anenergization time of a discharge control driver such asa transistor or IC for printing may be taken intoconsideration. In this case, a read value of atemperature detected by the sensor unit is corrected onthe basis of a sum of correction data for a temperatureincrease in the machine according to an energizationtime of the power supply unit and correction data for atemperature increase in the machine according to anenergization time of, e.g., a transistor for printing.According to this arrangement, correction can be morereliably performed.

Of printers which are operated by an AC powersupply, when an AC plug is connected, a main powersupply unit is energized to initialize a control unit,and the like, and an actual print operation isperformed after a power switch (software power switch)is turned on to energize the respective units of the main body. In a printer of this type, if anenergization time of the main power supply unit isreferred to as a hardware power-on time and anenergization time in which the respective units areenergized by actually turning on the software powerswitch is referred to as a software power-on time, ifthese times cause different heat generation amounts,the hardware and software power-on times areindependently measured, and a sum of correction valuesfrom the corresponding correction tables may besubtracted according to their lapses of time.

Fig. 26 is a view for explaining a temperatureincrease in the printer, and its correction operation.Tables 7 and 8 show temperature correction tablesaccording to hardware and software power-on times. Ascan be seen from Fig. 26, correction temperatures shownin Tables 7 and 8 are set in correspondence with atemperature increase in the machine ( T of the sensortemperature), and temperature increase correction canbe precisely performed. The software and hardwarepower on times are measured up to a maximum of 60minutes, and when they exceed 60 minutes, values at 60minutes are held.

Hardware Power-ON Time	0 min or more	10 min or more	20 min or more	40 min or more	50 min ormore
Correction Temperature
	0°C	-0.5°C	-1°C	-1.5°C	-2.0°C

Software Power-ON Time	0 min or more	2 min or more	5 min or more	10 min or more	30 min ormore
Correction Temperature
	0°C	-1.0°C	-1.5°C	-2.0°C	-2.5°C

Note that correction according to energizationtimes of the transistors and motors may be performed inaddition to the above-mentioned temperature increasecorrection.

When software is turned off or a print operationis completed, a temperature may be subtracted on thebasis of the software power-ON time or a print time.

For example, when the software is turned off inFig. 26, a timer for software power-ON (a timer forsoftware power-OFF may be added) is incremented from 0to measure a software power-OFF time until the softwareis turned on again. A value obtained by subtracting acorrection temperature obtained with reference to Table8 on the basis of the software power-OFF time from thecorrection temperature when the software is turned offis set as a final correction temperature. For example,in Fig. 26, since a correction temperature when thesoftware is turned off is -2.5°C, if the software isturned on 10 minutes later, the correction temperature of -2.0°C is subtracted from the correction temperatureof -2.5°C, and a difference of -0.5°C is determined asfinal correction temperature.

As described above, according to the thirdembodiment, if conventional closed-loop temperaturecontrol by a temperature sensor incorporated in therecording head is not performed, a means for measuringan ambient temperature is arranged in a recordingapparatus main body such as a printer, and a means formeasuring an energization time of a heat generationelement of the apparatus main body is arranged tocorrect a value measured by the means for measuring theambient temperature, so that a temperature of therecording head can be more precisely controlled to adesired temperature by open-loop control than in aconventional system.

Thermal problems in apparatus design such as therelative positional relationship among the temperaturesensor, the printed circuit board, and the recordinghead, ventilations, and the like can be solved, thusgreatly improving a degree of freedom in apparatusdesign.

Furthermore, an ambient temperature is correctedaccording to energization times of the apparatus mainbody and components in the machine which generate heat,so that a local difference in temperature increase inthe machine, or an error in an anticipated temperature of the recording head caused by a time difference dueto a difference in thermal time constant are corrected,thus attaining precise temperature control.

According to the present invention, a detectionlimit of a temperature sensor to be used is finely set,e.g., in units of 1 degree or 0.5 degree or less, and atemperature is corrected according to an energizationtime, thus attaining a more stable recording state.

The fourth embodiment of the present inventionwill be described with reference to Figs. 27 to 29 andTable 9.

In this embodiment, another correction operationdifferent from correction (steps S114, S115, S211,S315, and S316) using a carriage moving amount andperformed in the first to third embodiments in atemperature increase during printing will be describedbelow. In either embodiment, an energization timing ofatemperature control heater 10 falls within theacceleration (line up) intervals at both sides of aprintable range shown in Fig. 27. When the temperaturecontrol time (heater energization time) exceeds theabove acceleration intervals in temperature controlbefore printing, theheater 10 is energized prior tothe acceleration time. For this reason, an outputinterval of temperature control pulses for driving thetemperature control heater 10 in temperature controlduring printing corresponds to a carriage moving amount.

A correction coefficient is obtained on the basisof a pulse interval of the temperature control pulses,and carriage movement correction (pulse intervalcorrection) in temperature control during printing isperformed. Table 9 shows a data table used for pulseinterval correction. These data are obtained ascorrection coefficients as the percentage with respectto a reference interval (100%) when a period (1.2seconds in this embodiment) required for moving thecarriage throughout the width is defined as thereference interval.

Pulse Interval	0% or more	25% or more	50% or more	75% ormore
Correction Coefficient
	25%	50%	95%	100%

Pulse interval correction will be described withreference to Fig. 28 showing output timings of thetemperature control pulses and Fig. 29 showing a flowchart of pulse interval correction.

When a temperature control pulse is output in stepS401, an interval between the previous temperaturecontrol pulse and the current temperature control pulseis measured. In step S403, a temperature control pulseinterval correction table is referred to on the basisof the measured pulse interval, thereby obtaining a correction coefficient. A temperature controloperation amount during printing is corrected on thebasis of the obtained correction coefficient.

On the other hand, when it is determined in stepS401 that the temperature control pulse is not output,it is determined in step S404 whether 1.2 seconds havepassed after the previous output. If NO in step S404,the flow returns to step S401. In a normal printingoperation, since the temperature control pulse has amaximum of 1.2-second interval, the flow returns tostep S401.

However, when the next print signal is waited, 1.2seconds have often passed. In this case, the flowadvances to step S405. It is determined in step S405whether a capping state is set. If YES in step S405,no operation is performed, and the flow is ended.However, if YES in step S405, capping (Fig. 28) isperformed in this embodiment when six seconds havepassed upon completion of printing although capping isperformed by a known means. In this case, the sixseconds have passed to prevent a decrease in throughputoccurring when capping is performed upon completion ofprinting because capping and uncapping require muchtime.

If NO in step S405, a temperature control pulse His automatically output in step S406 to maintain thehead temperature to the same temperature as in a carriage stop state. Since capping is performed whensix seconds have passed upon completion of printing, amaximum of five temperature control pulses H areoutput. The flow then advances to steps S402.

In this embodiment, the same correction as incarriage moving amount correction is performed bymeasuring the temperature control pulse interval.Since the temperature control pulses H are kept outputto maintain the head temperature constant until cappingis performed even upon completion of printing,temperature control having higher precision than thatin a printing restart mode can be performed.

The fifth embodiment of the present invention willbe described with reference to Figs. 30 to 33 andTables 10 to 12.

This embodiment exemplifies an operation forprotecting the recording head from an over heat statealthough the recording head itself generates heat.

In the second embodiment described above, theover heat which tends to occur at a high print rate isprevented by correcting a temperature control power inaccordance with a print rate. For example, when aprint rate is 50% or more, as shown in Table 5, thecorrection coefficient is set to be 0%, and temperaturecontrol is not performed.

However, when a high print rate exceeding 50% iscontinued for a long period of time, an over heat state occurs by heat generated by the recording head itself.As is apparent from Tables 1 to 4, in order to preventover heat, temperature control is not performed.However, in this case, an over heat state occurs due toheat generated by the recording head itself.

In this embodiment, the self temperature increasein the recording head is anticipated on the basis of aprint rate. When an over heat state is determined bythe anticipated temperature increase and an ambienttemperature, printing in both directions is changed toprinting in one direction, thereby preventing overheat.

Sum Data Table
Low-response Duty	0% or more	12.5% or more	25% or more	40% or more	60% or more	80% ormore
Sum
	0	1	20	100	240	500
Max Value	-	180	2500	3400	11300	13000

Difference Data Table
Protect Value	0 or more	150 or more	1300 or more	5300 or more	11000 ormore
Difference
	1	20	100	240	500

Limit Data Table
Ambient Temperature	35°C or more	30°C or less	25°C% or less	20°C or less	15°C or less	15°C orless
Limit Value
	100	100	400	2600	8000	16000

Tables 10 and 11 are data tables of selftemperature increase control anticipation parameters, and Table 12 is a data table of self temperatureincrease determination control parameters.

A protect value is calculated to anticipate a selftemperature increase in the recording head duringprinting. The protect value is obtained by adding asum (Table 10) weighted with a low-response print rateevery one-line printing. However, when the protectvalue exceeds the MAX value corresponding to thelow-response print rate, the addition is not performed.As shown in Fig. 30, since a practical recording headhas an equilibrated temperature corresponding to aprint duty, a protect value has an upper limitcorresponding to the print rate. Fig. 30 shows arelationship between the temperature increase in therecording head and the corresponding protect value whenprinting is performed at a predetermined print rate.

When the low-response print rate is smaller thanthe previous print rate, a difference (Table 11)weighted by the protect value is subtracted everyprinting of one line. If the difference is smallerthan zero, no subtraction is performed because thedischarge amount of the recording head is determinednot by the print rate but by the increased temperature(protect value), as shown in Fig. 31. Fig. 31 shows atemperature increase/decrease in the printing head whenprinting is started at the predetermined print rate andthe print rate is decreased during printing. The differences in Table 11 correspond to operationsperformed when the print rate is decreased to 0%. Whenthe duty ratio is decreased to any value except forzero, the corresponding sum is added in correspondencewith the given print rate. Therefore, the differencesin Table 11 correspond to those in Fig. 31.

When the calculated protect value exceeds thecorresponding limit value (Table 12), over heatprotection is performed. This protection operation isperformed by changing printing in both directions toprinting in one direction. When printing in onedirection is set, the print rate is reduced to 1/2 thatin printing in both directions, thereby preventing overheat.

The low-response print rate is used to calculatethe protect value because the low-response print ratecorresponds to a temperature increase for a long periodof time, i.e., heat storage, and a high-response printrate corresponds to a local, instantaneous temperatureincrease.

An over heat protection operation of thisembodiment will be described with reference to flowcharts in Figs. 32 and 33.

A wait time counter, a print time counter, and atemperature increase correction timer are set (stepS501) upon power-on operation. The correction timer isthen started (step S502). In step S503, a wait time is read. When the count of the wait time counterrepresents 30 seconds or more, the print time counteris reset in step S504 due to a reason to be describedlater.

Operations in steps S505 to S515 are the same asthose (temperature increase correction in the machineand temperature control before printing) in steps S302to S312 in Fig. 24, and a detailed description thereofwill be omitted.

It is determined in step S516 on the basis of aprotect value whether a protect mode is required. IfYES in step S516, printing in both directions isinhibited in step S517. If a carriage moving amount is1/2 or less of the overall width in step S518, the modeis set in step S519 so that temperature control is notperformed in printing in one direction. The operationsin steps S518 and S519 are another series of correctionoperations corresponding to correction operationsperformed by the carriage moving amount in the first tofourth embodiments.

After thetemperature control heater 10 isenergized to perform temperature control duringprinting in step S520, printing of one line isperformed in step S521. The wait time counter isstarted (step S523). When printing is completed (stepS523), the flow returns to step S503.

In the third embodiment shown in Fig. 24, when printing is completed, the print time counter is alwaysreset (steps S320 and S321). However, in thisembodiment, the wait time timer is reset (steps S523,S503, and S504) when the wait time exceeds 30 seconds.When the wait time falls within 30 seconds, printing isassumed to be continued. Therefore, the temperaturecontrol power in temperature control during printing isset to be low.

The details of steps S516 and S517 will bedescribed below with reference to Fig. 33.

It is determined in step S601 whether a wait timeis equal to or more than 120 seconds. If YES in stepS601, the protect value is reset to "0" in step S602.When printing is not performed for a period of 120seconds or more, the temperature of the recording headis assumed to be decreased near the ambienttemperature, thereby releasing the protect mode.

In step S603, the number of printing dots for 15seconds is counted. In step S604, an averagelow-response print duty for past 120 seconds (8 times)is calculated of the number of printing dots counted instep S603. In step S605, the sum data table (Table 10)is referred to on the basis of the low-response printduty to obtain a sum. This sum is compared with theMAX value and if the protect value does not exceed theMAX value, the sum is added to the protect value (stepsS606 and S607).

In step S608, when the low-response print duty issmaller than the previous low-response print dutyobtained in step S604, discharge is taken intoconsideration. That is, in step S609, the differencedata table (Table 11) is referred to on the basis ofthe protect value to obtain a difference. In stepS610, the difference is subtracted from the protectvalue. In this case, when the protect value is smallerthan zero, it is set to be zero (steps S611 and S612).

A limit value is obtained with reference to thelimit data table on the basis of the ambienttemperature (step S613). If the protect value does notexceed this limit value, printing in both directions isset (steps S614 and S615). Therefore, this state iscanceled in printing in one direction (to be describedlater).

If the protect value exceeds the limit value,over heat is determined. In step S616, printing in onedirection is set. In this state, the print duty is setto 1/2 that in printing in both directions, over heatcan be prevented. Furthermore, when the ambienttemperature exceeds 30°C, the wait time is set so thata period of 1.2 seconds is inserted before printing(steps S617 and S618). The print duty is decreased to1/3 that in printing in both directions. Even if theambient temperature is high, the temperature of therecording head can be quickly decreased.

According to the fifth embodiment, as describedabove, the increase in temperature of the recordinghead is anticipated on the basis of the print rate, andover heat of the recording head is detected. When overheat of the recording head is determined, printing ischanged from printing in both directions to printing inone direction to reduce a print speed. An energyapplied to the recording head in unit time can bereduced to prevent over heat.

In addition, the equilibrated temperaturecorresponding to the print rate and a discharge amountcaused by a decrease in print rate is taken intoconsideration, thereby anticipating a temperatureincrease in the recording head. Therefore,high-precision protection against a temperatureincrease can be achieved.

When the temperature increase state is canceled bytemperature increase protection, the mode is restoredto printing in both directions to increase a recordingspeed.

In this embodiment, over heat of the recordinghead is protected by changing the mode from printing inboth directions to printing in one direction. However,any method may be employed if an energy applied to therecording head in unit time can be reduced. Forexample, a predetermined wait time may be providedprior to printing of the next line, and the pulse width of the discharge heater may be shortened.

In the first to fifth embodiments described above,print time data, wait time data, the energization timedata, and the like are preferably stored or timeroperations are preferably continued during thepower-off state due to the following reason. When datais lost upon a power-off operation, the previoustemperature of the recording head is unknown when thepower switch is turned on again. As a result, propertemperature control cannot be performed.

The sixth embodiment of the present invention willbe described with reference to the accompanyingdrawings.

Fig. 34 is a perspective view illustrating anink-jet recording apparatus which can suitably employ atemperature control method of the present invention.

The ink-jet recording apparatus is of a serialscan type in which a head cartridge integrallyincluding a recording head and an ink tank is mountedon a carriage moved along a recording medium P such asa paper sheet or a plastic thin sheet.

This ink-jet recording apparatus includes aninktank 1 and arecording head 2.

Therecording head 2 is an ink-jet recording headwhich discharges an ink by utilizing heat energy. Therecording head 2 comprises an electrothermal conversionelement array.

The ink-jet recording head 2 discharges an inkfrom a discharge port upon growth of bubbles by filmboiling generated by heat energy applied by theelectrothermal conversion element, thereby recordinginformation.

Theink tank 1 and therecording head 2 areintegrally arranged to constitute a disposable(exchangeable) head cartridge as a whole.

The head cartridge is mounted on acarriage 3, andthecarriage 3 is reciprocated in directions indicatedby a double-headed arrow A alongguide rails 4 so as tomove along the recording medium P. The recordingmedium P is brought into tight contact with aplatenroller 5 constituting a recording surface and is fed ina direction indicated by an arrowf upon driving of theplaten roller 5. Aflexible cable 6 comprises signallines for supplying ink discharge signal pulse currentsand recording head temperature adjustment currents totherecording head 2 through thecarriage 3. A printedcircuit board 7 comprises an electrical circuit forcontrolling the recording apparatus.

In the illustrated arrangement, atemperaturesensor 8, a head drive constant voltagesource powertransistor 18a, an A/D converter 16, a microprocessingunit (MPU) 17, and the like are mounted on the printedcircuit board 7. Thepower transistor 18a is one ofthe components constituting the electrical circuit on the printedcircuit board 7. Thepower transistor 18acontrols an ink discharge signal current to therecording head 2. Thetemperature sensor 8 comprises atemperature sensor consisting of a thermistor formeasuring a temperature. Thetemperature sensor 8 ismounted in contact with thepower transistor 18a. TheA/D converter 16 converts an analog signal from thetemperature sensor 9 to a digital signal. Themicroprocessing unit (MPU) 17 controls the respectivecomponents in the recording apparatus and performs aprocessing sequence such as temperature control.

Fig. 35 is a partial perspective view showing adetailed structure of therecording head 2. Referringto Fig. 35, anink path 20 which communicates with eachdischarge port 25 and acommon ink chamber 12 forsupplying an ink to eachink path 20 are formed in abase plate 24. Adischarge heater 13 serving as adischarge energy generating element for applyingdischarge heat energy to an ink in eachink path 20 isarranged in eachink path 20.

When recording is to be performed, an ink isfilled from theink tank 1 in thecommon ink chamber 12and eachink path 20 through ink supply pipes (notshown).

An electrical signal (e.g., an image signal) isapplied from the printedcircuit board 7 to eachdischarge heater 13 through theflexible cable 6. Eachdischarge heater 13 is heated to instantaneouslygenerate bubbles in part of the ink. Flying inkdroplets are discharged from eachdischarge port 25located at the downstream of thecorrespondingdischarge heater 13. Each ink droplet is attached tothe recording medium P to perform recording.

Fig. 36 is a graph showing results obtained bysimultaneously measuring temperatures of thebase plate24 of therecording head 2 and the temperatures of thepower transistor 18a when a predetermined pattern iscontinuously recorded on eight recording media by theink-jet recording apparatus described above.

As shown in Fig. 36, the temperature of thepowertransistor 18a is increased with an increase intemperature of therecording head 2. The temperatureof thepower transistor 18a as this electronic drivingelement is read by thetemperature sensor 9, and thetemperature of therecording head 2 can be measured.

Fig. 37 is a block diagram of a control system forsuitably practicing the temperature control method ofthe sixth embodiment.

As described above, a certain correlation ispresent between the temperatures of therecording head2 and the temperatures of thepower transistor 18a.However, different temperature curves are obtained dueto differences between the heat capacities of therecording head 2 and thepower transistor 18a.

For this reason, a power transistor is selected sothat the heat capacity of thepower transistor 18abecomes equal to that of therecording head 2, or aheat sink is coupled to the power transistor.Alternatively, an arithmetic operation is performed tocorrect a temperature of thepower transistor 18a bytheMPU 17 so as to uniquely determine the temperatureof therecording head 2 from the temperature of thepower transistor 18a. When the current temperature islower then a predetermined temperature, a short pulsewhich does not cause formation of bubbles and dischargeof an ink is applied to thedischarge heater 13 in anon-recording mode to heat therecording head 2. Whenthe current temperature exceeds the predeterminedtemperature, supply of the short pulse to the dischargeheater in the non-recording mode is stopped to adjustover heat of therecording head 2.

Fig. 38 is a partial perspective view showing arecording head 2 used for performing temperaturecontrol according to the seventh embodiment of thepresent invention. Referring to Fig. 38, atemperaturecontrol heater 10 is arranged to heat therecordinghead 2 near theink path 20 of therecording head 2 inaddition to adischarge heater 13 of eachink path 20.

Fig. 39 is a sectional view showing part of aprintedcircuit board 7 of this embodiment. Referringto Fig. 39, a constant voltagesource power transistor 18b for driving thetemperature control heater 10 isarranged on the printedcircuit board 7 in addition toa recording head drivingpower transistor 18a.Temperature sensors 8 are arranged in contact with thepower transistors 18a and 18b, respectively.

Fig. 40 is a block diagram of a control systemsuitably employing a temperature control method of thisembodiment.

Referring to Fig. 40, power transistors areselected so that each of the heat capacities of thedischarge heaterdrive power transistor 18a and thetemperature control drivingpower transistor 18b is setto be 1/2 the heat capacity of therecording head 2.Alternatively, a heat sink is coupled to each powertransistor to set so that a temperature increase ineachpower transistor 18a or 18b is doubled from thetemperature increase in therecording head 2.

The temperatures of thepower transistors 18a and18b are measured bytemperature sensors 8, andtemperature signals from thesensors 8 are convertedinto digital signals by A/D converters 16. The digitalsignals are multiplied with each other in theMPU 17,and the product is additionally multiplied with acorrection coefficient, thereby uniquely determiningthe temperature of the recording head from thetemperatures of thepower transistors 18a and 18b.

An ambient temperature (room temperature) sensor may be arranged and combined with the twotemperaturesensors 8 attached to thepower transistors 18a and18b, thereby correcting the measuring temperatures.

When the measured temperatures of the twopowertransistors 18a and 18b are lower than a predeterminedtemperature, thetemperature control heater 10 isturned on, and a short pulse which does not causeformation of bubbles of the ink is applied to it,thereby heating therecording head 2.

When the measured temperatures of the twopowertransistors 18a and 18b exceed the predeterminedtemperature, at least one of thetemperature controlheater 10 is turned off, and supply of a short pulse tothedischarge heater 13 is stopped is performed toprevent over heat of therecording head 2.

Figs. 41A and 41B are partial sectional views ofprintedcircuit boards 7 for performing temperaturecontrol according to the eighth embodiment of thepresent invention.

Referring to Fig. 41A, a discharge heater drivingpower transistor 18a and a temperature control heaterdrivingpower transistor 18b are in contact with onetemperature sensor 9.

Referring to Fig. 41B, a discharge heater drivingpower transistor 18a and a temperature control heaterdrivingpower transistor 18b are in contact with aheatsink 28. In addition, atemperature sensor 8 is thermally coupled to theheat sink 28.

The temperature control method of this embodimentcan be practiced using the same arrangement as thecontrol system shown in Fig. 40.

In the arrangement of Fig. 41A, a total heatcapacity of the twopower transistors 18a and 18b isset to be equal to that of therecording head 2, or ananalog signal from thetemperature sensor 8 isconverted into a digital signal by an A/D converter,and the digital signal is subjected to correctionprocessing in anMPU 17. Therefore, the temperature oftherecording head 2 can be uniquely determined fromthe temperatures measured by thetemperature sensor 8.When the measured temperature is the predeterminedtemperature or less, at least one of thetemperaturecontrol heater 10 and thedischarge heater 13 is usedto heat therecording head 2. When the measuredtemperature exceeds the predetermined temperature,heating of the recording head by at least one of thetemperature control heater 10 and thedischarge heater13 is stopped, thereby performing temperature controlof therecording head 2.

In the arrangement of Fig. 41B, a total heatcapacity of the twopower transistors 18a and 18b andtheheat sink 28 is selected to be equal to that of therecording head 2. Alternatively, the analog signalsfrom thetemperature sensor 8 are converted into digital signals by the A/D converters 16, and thedigital signals are subjected to correction processingin theMPU 17. Therefore, the temperature of therecording head 2 is uniquely determined in accordancewith the temperatures measured by thetemperaturesensor 8. In the same manner as described above, whenthe measure temperatures are the predeterminedtemperature or less, therecording head 2 is heated byat least one of thetemperature control heater 10 andthedischarge heater 13. However, when the measuredtemperatures exceed the predetermined temperature,heating of therecording head 2 by at least one of thetemperature control heater 10 and thedischarge heater13 is stopped, thereby controlling the temperature oftherecording head 2.

Fig. 42 is a partial sectional view of a printedcircuit board for performing temperature controlaccording to the ninth embodiment of the presentinvention. Fig. 43 is a block diagram of a controlsystem suitably performing the temperature control ofthis embodiment.

Referring to Fig. 42, atemperature sensor 8 islocated near a discharge heater drivingpowertransistor 18a. In this case, in order to cause thetemperature sensor 8 to effectively sense radiationheat or convection heat from the discharge heaterdrivingpower transistor 18a, thetemperature sensor 8 is preferably located at a level higher than a heatingsource of the discharge heater drivingpower transistor18a since heat is accumulated in the upper portion.

Referring to Fig. 43, in the control system ofthis embodiment, radiation heat and reflection heatfrom thepower transistor 18a for thedischarge heater13 are measured by thetemperature sensor 8, and ananalog signal from thetemperature sensor 8 isconverted into a digital signal by the A/D converter16. Thereafter, the digital signal is subjected tocorrection processing, thereby anticipating thetemperature of therecording head 2.

The temperature of therecording head 2 can bestably controlled to a predetermined temperature by theabove control system.

According to the sixth to ninth embodiments asdescribed above, closed-loop temperature control by thetemperature sensor incorporated in a conventionalrecording head need not be performed. By using thetemperature sensor 8 arranged in the recordingapparatus, the temperature of the heat-generating powertransistor (driving element) for applying a heat energyto therecording head 2 is measured. The temperatureof the recording head is indirectly measured, and thetemperature of therecording head 2 can be controlledto a desired temperature.

An expensive recording head temperature sensor can be eliminated, variations in temperature measurementvalues of the recording head can be eliminated, themanufacturing cost can be greatly reduced, and theproduct yield can be greatly increased.

Each embodiment described above exemplifies adisposable cartridge type recording head. However, thetemperature control method of the present invention isnot limited to this. The present invention is equallyapplicable to use of a recording head of a type whichdoes not substantially require replacement, therebyobtaining the same effect as described above.

In each embodiment, the power transistor is usedas a driving element for applying a heat energy to therecording head 2. However, the drive element is notlimited to the power transistor.

Each embodiment described above exemplifies aserial scan type ink-jet recording apparatus using aserial scan type ink-jet recording head (headcartridge) mounted on thecarriage 3. However, thepresent invention is also applicable to a line typeink-jet recording apparatus using a line type ink-jetrecording head which covers a recording area in thewidthwise direction of the recording medium, andink jet recording apparatuses employing other recordingschemes to obtain the same effect as described above.

The present invention is used in a variety ofapplications regardless of the number of recording heads.

The present invention has excellent effects in abubble-jet type recording head and its recordingapparatus in the ink-jet recording schemes.

As its typical arrangement and principle, thebasic principles disclosed in, e.g., U.S.P. Nos.4,723,129 and 4,740,796 are preferable. This schemecan be applied to any one of an on-demand type schemeand a continuous type scheme. In particular, when theabove principle is applied to the on-demand typescheme, at least one driving signal corresponding torecording information is applied to an electrothermalconversion element located in correspondence with asheet having a liquid (ink) layer or an ink path so asto obtain an abrupt temperature increase, therebycausing the electrothermal conversion element togenerate a heat energy. Film boiling is caused on theheat application surface of the recording head, and abubble can be effectively formed in a liquid (ink) in aone-to-one correspondence with this driving signal.The liquid (ink) is discharged through thecorresponding discharge opening upon growth andcontraction of this bubble, thereby forming at leastone droplet. When this driving signal is a pulsesignal, the bubble is instantaneously grown andcontracts, high-speed liquid (ink) discharge can bemore preferably performed. Preferable pulse shapes are disclosed in U.S.P. Nos. 4,463,359 and 4,345,262. Whenconditions associated with a temperature increase rateof the heat application surface, as disclosed in U.S.P.No. 4,313,124 is employed, better recording can beperformed.

A recording head arrangement as heat applicationportions arranged in the bent areas, as disclosed inU.S.P. Nos. 4,558,333 and 4,459,600, is alsoincorporated in the present invention in addition to acombination (linear ink path or a right-angled flowpath) of a discharge port, an ink path, and anelectrothermal conversion element, as disclosed in eachspecification of the prior arts. In addition, thepresent invention is effective to an arrangement havinga common slit as a discharge portion of theelectrothermal conversion elements, disclosed inJapanese Laid Open Patent Application No. 59-123670 andto an arrangement having a correspondence between anopening for absorbing an energy pressure wave and adischarge port, as disclosed in Japanese Laid-OpenJapanese Application No. 59-138461.

As a full-line type recording head having a lengthcorresponding to the width of the maximum recordingmedium used in the recording apparatus, a plurality ofrecording heads disclosed in the above specificationsmay be combined to cover the entire recording length,or a single recording head may be used. The present invention can further enhance the effect as describedabove.

In addition, the present invention is alsoeffective when an exchangeable chip type recording headcapable of being electrically connected to theapparatus main body and supplying an ink from theapparatus main body, or a cartridge type recording headintegrally formed with the recording head is mounted inthe apparatus main body.

A recording head recovery means and asupplementary assisting means are preferably arrangedas constituting components of the recording apparatusof the present invention to further enhance stabilityof the effect of the present invention. Examples are arecording head capping means, a recording head cleaningmeans, a recording head pressing means, a recordinghead suction means, an electrothermal conversionelement, another heating element, a combination of theelectrothermal conversion element and this heatingelement, and an arrangement for setting a preliminarydischarge mode for discharging independently ofrecording so as to perform stable recording.

A recording mode of the recording apparatus is notlimited to a recording mode for only a major color suchas black. An integral full-color recording head or aplurality of single-color recording heads may be used.The present invention is also effective to an apparatus having at least one of a plurality of different colorsor a color mixing full-color mode.

In each embodiment described above, a liquid inkis used. However, an ink which is solidified at roomtemperature or less, an ink which is softened or meltedeven at room temperature, or the like may be used.Alternatively, an ink which is solidified or melted inthe general temperature control range of 30°C to 70°Cmay be used in ink-jet printing. That is, any ink maybe used when it is melted when a print signal isapplied to the recording head. A temperature increaseby a heat energy may be positively prevented by using aphase transition from the solid phase to the liquidphase, or an ink which is solidified in an exposedstate to aim at prevention of evaporation of the inkmay be used. In either case, an ink which is meltedupon reception of the print signal of the heat energymay be used. In this case, the melted ink isdischarged. In addition, an ink which is solidified atthe time of its arrival on the recording medium, or anink which is melted upon reception of heat energy maybe applied to the present invention. In this case, asdescribed in Japanese Laid-Open Patent ApplicationNo. 54-56847 or 60-71260, an ink may oppose thecorresponding electrothermal conversion element whilethe ink is held in a recess portion of a porous sheetor held as a liquid or solid body in a through hole. According to the present invention, a film boilingscheme is most effective for these inks.

In addition, as the form of an ink-jet recordingapparatus, the apparatus may be used as an image outputterminal for a data processing unit such as a computer,a copying machine as a combination with a reader or thelike, and a facsimile apparatus having atransmission/reception function.

According to the present invention, as has beendescribed above, correction associated with thetemperature of the control circuit area is performedfor a control object member (the ink-jet recordingapparatus recording means in each embodiment) toeliminate a control error as in a technique fordetecting the state of the recording means while adirect temperature measurement is performed. Sincedetection or anticipation precision is better thantemperature control by the conventional temperaturesensor and the detection error range of the temperaturesensor itself, execution modes based on varioustemperatures can be accurately performed.

In addition to the ink-jet recording head utilizinga heat energy, the present invention is applicable toheating elements driven individually or in units ofpredetermined groups, such as a thermal head forapplying a heat energy to an ink ribbon or a porous inkconvey unit. In this case, any temperature sensor need not be arranged directly on or near the heatingelement. Disconnections of the sensor and sensorwiring lines can be eliminated, and the measurement isfree from sensor variations. In particular, in arecording heating element array, each heating portionis locally heated to slightly change the response ofthe temperature sensor, thereby disabling accuratedetermination. The present invention can solve this.

In particular, the present invention providesmarvelous effects in a control object member (e.g., anink-jet recording head using an ink (solid or liquid))having various thermal parameters such as an ink heatcapacity, a head structure, and heating of the abovemember. These parameters cause variations in positionfor accurately determining the temperature due to a useor drive state. Therefore, it is difficult todetermine a timing at which accurate determination isperformed. However, the present invention can solvethis drawback.

In a bubble-jet machine utilizing an ink-jetboiling film, proposed by CANNON INC., the filmtemperature locally exceeds 300 °C due toheat-insulating expansion of bubbles. Even if theparameters having large variations are included, or alocal heating portion such as a driving switching diodeis included, variation factors can be systematicallydetermined to perform temperature control, thus proving superiority of the present invention over the priorarts.

In the scanning type recording apparatus forscanning a recording head to perform recording, anoperation error of the temperature detection sensoroccurs due to a scanning speed and a difference betweenspeeds during scanning and the stop state. The presentinvention can solve this problem.

In the embodiments described above, technicalarrangements based on the description of the respectivecomponents, and their modifications may be incorporatedin the present invention in a combination withoutdeparting the scope of the appended claims.

An ink-jet recording apparatus for discharging anink droplet from a recording head to perform recordingincludes a heating element array for heating therecording head, a temperature sensor for measuring anambient temperature, a timer for measuring a timeassociated with a temperature variation of therecording head during a recording operation, and acontrol unit for controlling an energy supplied to theheating element array on the basis of the ambienttemperature measured by the temperature sensor and thetime measured by the timer.

Claims (41)

1. An ink-jet recording apparatus for discharging an inkdroplet from a recording head (2; IJH) to perform recording,said apparatus comprising heat means (10) for heating saidrecording head to control a temperature of ink,
   characterized by

   temperature measurement means (8) for measuring anambient temperature,

   timer means for measuring a time period in which achange in temperature of said recording head (2; IJH) iseffected during a recording operation, and

   control means (17; MPU; 22) for subsequently controllingan energy to be supplied to said heat means (10) on the basisof the time period measured by said timer means during theprevious recording operation with respect to the ambienttemperature measured by said temperature measurement means(8).
2. An apparatus according to claim 1, wherein

   said timer means measures a record time of saidrecording head, the record time being a time period duringwhich said recording head is conveyed and performs recording,and

   said control means supplies the energy to said heatmeans during the recording operation.
3. An apparatus according to claim 2, wherein

   said control means supplies the energy to said heatmeans immediately before each recording of one line.
4. An apparatus according to claim 3, wherein

   said control means controls the energy supplied to saidheat means on the basis of an energy supply interval of saidheat means.
5. An apparatus according to claim 3, wherein

   said control means controls the energy supplied to saidheat means on the basis of a content of a recording signal ofnext and subsequent lines.
6. An apparatus according to claim 2, wherein

   said timer means measures the record time of saidrecording head by counting one of a number of recording linesand a number of recording characters.
7. An apparatus according to claim 1, wherein

   said timer means measures a non-record time of saidrecording head, the non-record time being a time periodduring which said recording head does not perform recording,and

   said control means supplies the energy to said heatmeans just before the recording operation.
8. An apparatus according to claim 1, wherein

   said timer means measures a record time and a non-recordtime of said recording head, the record time being a timeperiod during which said recording head is conveyed andperforms recording, the non-record time being a time periodduring which said recording head does not perform recording,and

   said control means controls the energy supplied to saidheat means during the recording operation on a basis of theambient temperature and the record time, and controls theenergy supplied to said heat means prior to the recordingoperation on a basis of the ambient temperature and the non-recordtime.
9. An apparatus according to claim 8, further comprising:

   print rate measurement means for measuring a print rateduring a predetermined time of said recording head, andwherein

   said control means controls the energy supplied to saidheat means on the basis of the print rate measured by saidprint rate measurement means.
10. An apparatus according to claim 9, wherein

    said control means controls the energy supplied to saidheat means on the basis of the ambient temperature, the non-recordtime, and an anticipated temperature of said recordinghead at an end of previous printing.
11. An apparatus according to claim 9, wherein

    said print rate measurement means measures a print rateby counting a number of discharge pulses per unit time.
12. An apparatus according to claim 9, wherein

    said print rate measurement means measures print ratesof a first time period and a second time period longer thanthe first time period, and

    said control means controls the energy supplied to saidheat means on the basis of the print rates of the first andsecond time periods.
13. An apparatus according to claim 8, further comprising:

    energization time measurement means for measuring anenergization time of said apparatus, and wherein

    said control means controls the energy supplied to saidheat means on the basis of the energization time measured bysaid energization time measurement means.
14. An apparatus according to claim 13, wherein

    said control means modifies the ambient temperature ofsaid recording apparatus on the basis of the energizationtime, controls the energy supplied to said heat means during the recording operation on the basis of the modified ambienttemperature and the record time, and controls the energysupplied to said heat means prior to the recording operationon the basis of the corrected ambient temperature and thenon-record time.
15. An apparatus according to claim 13, wherein

    said energization time measurement means measures afirst energization time for energizing a power source unit insaid apparatus and a second energization time for energizingeach component in said apparatus, and

    said control means controls the energy supplied to saidheat means on the basis of the first and second energizationtimes.
16. An apparatus according to claim 8, wherein

    said recording head has a plurality of discharge portsfor discharging the ink with the heat energy.
17. An apparatus according to claim 8, wherein

    said recording head comprises a plurality of dischargeports for discharging ink, and heat energy generation means,arranged in units of discharge ports, for causing a statechange in ink by heat, discharging the ink from saiddischarge ports on the basis of the state change, and formingflying droplets.
18. An apparatus according to claim 8, wherein

    said recording head comprises a disposable recordinghead detachably formed in said apparatus.
19. An apparatus according to claim 8, wherein

    said recording head comprises a full-line recording headhaving a plurality of discharge ports spanning an entirerecording width of a recording medium.
20. An apparatus according to claim 8, wherein

    said apparatus is applied to a facsimile apparatus forrecording a recording signal received through a communicationline.
21. An apparatus according to claim 8, wherein

    said control means controls the supply energy on thebasis of a pulse width of a drive pulse supplied to said heatmeans.
22. An apparatus according to claim 1, further comprising:

    print rate measurement means for measuring a print ratein a predetermined time period of said recording head;

    temperature increase anticipating means for determininga temperature increase caused solely by a recording operationof said recording head on a basis of the print rate measuredby said print rate measurement means; and

    temperature increase protection means for limitingsupply of the recording energy to said recording head on thebasis of the temperature increase determinated by saidtemperature increase anticipating means.
23. An apparatus according to claim 22, wherein

    said temperature increase protection means limits supplyof the recording energy by changing recording in bothdirections to recording in one direction.
24. An ink-jet recording apparatus for discharging an inkdroplet from a recording head (2; IJH) to perform recording,said apparatus comprising heat means (10) for heating saidrecording head to control a temperature of ink,
    characterized by

    temperature measurement means (8) for measuring anambient temperature,

    print rate measurement means for measuring a print rateof said recording head (2; IJH) during a predetermined timeduring a recording operation, and

    control means (17, MPU; 22) for subsequently controllingan energy to be supplied to said heat means (10) on the basisof the print rate measured by said print rate measuring meansduring the previous recording operation with respect to theambient temperature measured by said temperature measurementmeans (8).
25. An apparatus according to claim 24, wherein

    said print rate measurement means measures the printrate by counting the number of ink discharge pulses per unittime.
26. An apparatus according to claim 24, wherein

    said print rate measurement means measures print ratesof a first time period and a second time period longer thanthe first period, and

    said control means controls the energy supplied to saidheat means on the basis of the print rates of the first andsecond time periods.
27. An apparatus according to claim 24, further comprising:

    timer means for measuring a record time of saidrecording head, the record time being a time period duringwhich said recording head is conveyed and performs recording,and wherein

    said control means controls the energy supplied to saidheat means on the basis of the record time measured by saidtimer means.
28. An apparatus according to claim 24, further comprising:

    timer means for measuring a non-record time of saidrecording head, the non-record time being a time periodduring which said recording head does not perform recording;and wherein

    said control means controls the energy supplied to saidheat means on the basis of the non-record time measured bysaid timer means.
29. An apparatus according to claim 24, whereinsaid recording head has a plurality of discharge ports fordischarging the ink with the heat energy.
30. An apparatus according to claim 24, wherein

    said recording head comprises a plurality of dischargeports for discharging ink, and heat energy generation means,arranged in units of discharge ports, for causing a statechange in ink by heat, discharging the ink from saiddischarge ports on the basis of the state change, and formingflying droplets.
31. An apparatus according to claim 24, wherein

    said recording head comprises a disposable recordinghead detachably formed in said apparatus.
32. An apparatus according to claim 24, wherein

    said recording head comprises a full-line recording headhaving a plurality of discharge ports spanning an entirerecording width of a recording medium.
33. An apparatus according to claim 24, wherein

    said apparatus is applied to a facsimile apparatus forrecording a recording signal received through a communicationline.
34. An apparatus according to claim 24, wherein

    said control means controls the supply energy on thebasis of a pulse width of a drive pulse supplied to said heatmeans.
35. An ink-jet recording apparatus for discharging an inkdroplet from a recording head (2; IJH) to perform recording,said apparatus comprising heat means (10) for heating saidrecording head (2; IJH) to control a temperature of ink andenergy supplying means for supplying an energy to said heatmeans just before recording of one line,
    characterized by

    temperature measurement means (8) for measuring anambient temperature,

    interval measurement means for measuring an energysupply interval of said energy supplying means during arecording operation, and

    control means (17, MPU; 22) for subsequently controllingthe energy supplied to said heat means (10) on the basis ofthe energy supply interval measured by said intervalmeasurement means during the previous recording operationwith respect to the ambient temperature measured by saidtemperature measurement means (8).
36. An apparatus according to claim 35, wherein

    said recording head has a plurality of discharge portsfor discharging the ink with the heat energy.
37. An apparatus according to claim 35, wherein

    said recording head comprises a plurality of dischargeports for discharging ink, and heat energy generation means,arranged in units of discharge ports, for causing a statechange in ink by heat, discharging the ink from saiddischarge ports on the basis of the state change, and formingflying droplets.
38. An apparatus according to claim 35, wherein

    said recording head comprises a disposable recordinghead detachably formed in said apparatus.
39. An apparatus according to claim 35, wherein

    said recording head comprises a full-line recording headhaving a plurality of discharge ports spanning an entirerecording width of a recording medium.
40. An apparatus according to claim 35, wherein

    said apparatus is applied to a facsimile apparatus for recording a recording signal received through a communicationline.
41. An apparatus according to claim 35, wherein

    said control means controls the supply energy on thebasis of a pulse width of a drive pulse supplied to said heatmeans.

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