US20200071118A1 - Sheet processing apparatus and image forming system including multiple folding members - Google Patents

Abstract

A sheet processing apparatus that forms a folding line on a sheet includes first and second folding rollers that form a folding line on the sheet by rotating a bent sheet while pinching from sheet surfaces and a first pressing unit that presses the second folding roller against the first folding roller in an arbitrary portion in a rotating shaft direction of the second folding roller.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 16/116,161, filed on Aug. 29, 2018, which is a continuation application of and claims priority under 35 U.S.C. § 120/121 to U.S. application Ser. No. 15/613,583 filed Jun. 5, 2017, now granted as U.S. Pat. No. 10,124,981 on Nov. 13, 2018, which is a continuation application of U.S. application Ser. No. 14/706,153 filed May 7, 2015, now granted as U.S. Pat. No. 9,688,502 on Jun. 27, 2017, which claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2014-104446 filed in Japan on May 20, 2014 and Japanese Patent Application No. 2015-010430 filed in Japan on Jan. 22, 2015, the entire contents of each of which are hereby incorporated by reference herein.
BACKGROUND OF THEINVENTION1. Field of the Invention
• The present invention relates to a sheet processing apparatus and an image forming system, and more particularly, to a sheet folding process.
2. Description of the Related Art
• In recent years, information has been converted in a digital form, and an image processing apparatus such as a printer or a facsimile used to output digital information or a scanner used to convert a document in a digital form has become an indispensable device. Such an image processing apparatus has, for example, an image capturing function, an image forming function, and a communication function and is usually configured as a multifunction peripheral that can be used as a printer, a facsimile, a scanner, and a copy machine.
• Among such multifunction peripherals, a multifunction peripheral equipped with a folding processing apparatus that performs a folding process of folding a sheet on which an image is formed after rendering an image by forming an image on a fed sheet has been known. Typically, the folding processing apparatus includes a folding processing roller pair configured with two folding processing rollers laterally bridging in a direction parallel to a folding line to be formed, and forms a folding line at a folding position by pinching a bend formed at the folding position from both sheet surfaces through the folding processing roller pair while rotating the folding processing roller pair (for example, JP 2012-144312 A).
• At this time, the folding processing apparatus generates pressing force over the whole area in a direction perpendicular to a sheet conveyance direction by applying force for pressing the folding processing rollers against each other in both ends of the folding processing roller pair in the direction perpendicular to the sheet conveyance direction. Thus, in the folding processing apparatus, when the sheet is pinched by the folding processing roller pair, repulsive force is generated from the sheet against the pressing force, but the force of pressing the folding processing roller against each other acts as a force countering the repulsive force near both ends in the direction perpendicular to the sheet conveyance direction, and thus the sheet can be sufficiently pressed by the force although the repulsive force acts.
• Meanwhile, in the folding processing apparatus according to the related art, since no force countering the repulsive force acts near a central portion in the direction perpendicular to the sheet conveyance direction, when the repulsive force acts, the folding processing rollers are bent in a direction opposite to a pressing direction, and thus there is a problem in that it is difficult to sufficiently press the sheet.
• Further, in the folding processing apparatus according to the related art, since the force for pressing the folding processing rollers against each other acts on both ends of the folding processing roller pair in the direction perpendicular to the sheet conveyance direction, a deviation of pressing force occurs between both ends. As a result, in the folding processing apparatus according to the related art, it is difficult to press the sheet evenly at one end and the other end, and a wrinkle or a skew occurs in the sheet, or the folding position is misaligned, resulting in a reduction in a folding quality.
• Therefore, there is a need for a sheet processing apparatus and an image forming system capable of forming a folding line on a sheet effectively and improve a folding quality.
SUMMARY OF THE INVENTION
• It is an object of the present invention to at least partially solve the problems in the conventional technology.
• There is provided a sheet processing apparatus that forms a folding line on the sheet, includes first and second folding rollers that form a folding line on a sheet by rotating a bent sheet while pinching from sheet surfaces, and a first pressing unit that presses the second folding roller against the first folding roller in an arbitrary portion in a rotating shaft direction of the second folding roller.
• The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a diagram schematically illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention;
• FIG. 2 is a diagram schematically illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention;
• FIG. 3 is a block diagram schematically illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention;
• FIG. 4 is a block diagram schematically illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention;
• FIG. 5 is a cross-sectional view illustrating a folding processing unit according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 6A to 6C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 7A to 7C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 8A to 8C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIG. 9 is a diagram illustrating an exemplary shape of a folded sheet that has been subjected to a folding process by a folding processing unit according to an embodiment of the present invention;
• FIGS. 10A to 10C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 11A to 11C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 12A to 12C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIG. 13 is a diagram illustrating an exemplary shape of a folded sheet that has been subjected to a folding process by a folding processing unit according to an embodiment of the present invention;
• FIGS. 14A to 14C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 15A to 15C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIGS. 16A to 16C are cross-sectional views illustrating a folding processing unit performing a folding processing operation in an image forming apparatus according to an embodiment of the present invention when viewed in a direction perpendicular to a sheet conveyance direction;
• FIG. 17 is a diagram illustrating an exemplary shape of a folded sheet that has been subjected to a folding process by a folding processing unit according to an embodiment of the present invention;
• FIGS. 18A and 18B are diagrams illustrating exemplary shapes of a folded sheet that has been subjected to a folding process by a folding processing unit according to an embodiment of the present invention;
• FIG. 19 is a perspective view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a folding processing unit according to an embodiment of the present invention;
• FIG. 20 is a perspective view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a folding processing unit according to an embodiment of the present invention that are cut in a central portion in a direction perpendicular to a sheet conveyance direction;
• FIG. 21 is a cross-sectional view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a central portion in a direction perpendicular to a sheet conveyance direction in a folding processing unit according to an embodiment of the present invention when viewed in the direction perpendicular to the sheet conveyance direction;
• FIG. 22 is a diagram for describing a state in which a first folding processing roller pressing member fixing stay is fixed to a support plate according to an embodiment of the present invention;
• FIG. 23 is a diagram illustrating a pressing force distribution in a direction perpendicular to a sheet conveyance direction when a folding processing unit according to a related art presses a sheet through a first folding processing roller pair or a second folding processing roller pair;
• FIG. 24 is a diagram illustrating a pressing force distribution in a direction perpendicular to a sheet conveyance direction when a folding processing unit according to an embodiment of the present invention presses a sheet through a first folding processing roller pair or a second folding processing roller pair;
• FIG. 25 is a perspective view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a folding processing unit according to an embodiment of the present invention that are cut in a central portion in a direction perpendicular to a sheet conveyance direction;
• FIG. 26 is a cross-sectional view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a central portion in a direction perpendicular to a sheet conveyance direction in a folding processing unit according to an embodiment of the present invention when viewed in the direction perpendicular to the sheet conveyance direction;
• FIG. 27 is a perspective view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a folding processing unit according to an embodiment of the present invention;
• FIG. 28 is a perspective view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a folding processing unit according to an embodiment of the present invention; and
• FIG. 29 is a cross-sectional view illustrating a first forward-reverse rotating roller, a first folding processing roller, and a second folding processing roller in a central portion in a direction perpendicular to a sheet conveyance direction in a folding processing unit according to an embodiment of the present invention when viewed in the direction perpendicular to the sheet conveyance direction.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the appended drawings. In the present embodiment, an image forming apparatus that forms an image on a sheet such as a fed sheet and then performs a folding process of forming a folding line in the image-formed sheet in a direction perpendicular to a sheet conveyance direction will be described as an example.
• An image forming apparatus according to the present embodiment includes a folding processing roller pair configured with two folding processing rollers laterally bridging in a direction parallel to a folding line to be formed, and forms a folding line at a folding position by pinching a bend formed at the folding position from both sheet surfaces through the folding processing roller pair while rotating the folding processing roller pair.
• In the image forming apparatus having the above configuration, one of gist of the present embodiment lies in that force of pressing the two folding processing rollers configuring the folding processing roller pair against each other is caused to act near a central portion in a direction perpendicular to a sheet conveyance direction serving as a rotating shaft direction thereof. Thus, the image forming apparatus according to the present embodiment can generate sufficient pressing force evenly over the whole area in the direction perpendicular to the sheet conveyance direction. According to the image forming apparatus according to the present embodiment, it is possible to form a folding line on a sheet effectively and improve a folding quality.
• First, an overall configuration of animage forming apparatus1 according to the present embodiment will be described with reference toFIG. 1.FIG. 1 is a diagram schematically illustrating an overall configuration of theimage forming apparatus1 according to the present embodiment. Theimage forming apparatus1 according to the present embodiment includes animage forming unit2, afolding processing unit3, apost-processing unit4, and ascanner unit5 as illustrated inFIG. 1.
• Theimage forming unit2 generates rendering information of CMYK (Cyan Magenta Yellow Key Plate) based on input image data, and performs an image forming output on a fed sheet based on the generated rendering information. Thefolding processing unit3 performs a folding process on an image-formed sheet conveyed from theimage forming unit2. In other words, in the present embodiment, thefolding processing unit3 functions as a sheet processing apparatus. Thereafter, thepost processing unit4 performs post-processing such as binding, stapling, or punching on the folded sheet conveyed from thefolding processing unit3.
• Thescanner unit5 converts an original in a digital form by scanning an original through a linear image sensor in which a plurality of photodiodes are arranged in a line, and light receiving elements such as a Charge Coupled Device (CCD) image sensor or a Complementary Metal Oxide Semiconductor (CMOS) image sensor are arranged in parallel to the photodiodes. Here, theimage forming apparatus1 according to the present embodiment is a MultiFunction Peripheral (MFP) that has, for example, an image capturing function, an image forming function, and a communication function and can be used as a printer, a facsimile, a scanner, or a copy machine.
• FIG. 1 illustrates the configuration of theimage forming apparatus1 in which thefolding processing unit3 is arranged in the body of theimage forming unit2, but theimage forming apparatus1 may have a configuration in which thefolding processing unit3 is independently arranged as illustrated inFIG. 2.FIG. 2 is a diagram schematically illustrating an overall configuration of theimage forming apparatus1 according to the present embodiment.
• Next, a hardware configuration of theimage forming apparatus1 according to the present embodiment will be described with reference toFIG. 3.FIG. 3 is a block diagram schematically illustrating a hardware configuration of theimage forming apparatus1 according to the present embodiment. Here, theimage forming apparatus1 includes an engine for implementing a scanner, a printer, the folding process, post-processing, and the like in addition to the hardware configuration illustrated inFIG. 3.
• Theimage forming apparatus1 according to the present embodiment has the same configuration as a common server, a common personal computer (PC), or the like as illustrated inFIG. 3. In other words, in theimage forming apparatus1 according to the present embodiment, a Central Processing Unit (CPU)10, a Random Access Memory (RAM)20, a Read Only Memory (ROM)30, a Hard Disk Drive (HDD)40, and an I/F50 are connected with one another via abus90. Further, a Liquid Crystal Display (LCD)60, an operatingunit70, and adedicated device80 are connected to the I/F50.
• TheCPU10 is an operation unit, and controls an operation of theimage forming apparatus1 in general. TheRAM20 is a volatile storage medium in which reading and writing of information can be performed at a high speed, and used as a work area when theCPU10 processes information. TheROM30 is a read only non-volatile storage medium, and stores a program such as firmware. TheHDD40 is a non-volatile storage medium in which reading and writing information can be performed, and stores an Operating System (OS), various kinds of control programs, various kinds of application programs, or the like.
• The I/F50 connects thebus90 with various kinds of hardware or networks, and performs control. TheLCD60 is a visual user interface by which the user checks a state of theimage forming apparatus1. The operatingunit70 is a user interface such as a keyboard or a mouse by which the user inputs information to theimage forming apparatus1.
• Thededicated device80 is hardware for implementing a dedicated function in theimage forming unit2, thefolding processing unit3, thepost-processing unit4, and thescanner unit5, and is a plotter device that performs an image forming output on a plane of paper in theimage forming unit2. Further, thededicated device80 is a conveying mechanism that conveys a sheet or a folding processing mechanism that folds a conveyed sheet in thefolding processing unit3. A configuration of the folding processing mechanism included in thefolding processing unit3 is one of the gists of the present embodiment.
• Further, thededicated device80 is a post-processing mechanism that performs post processing on the sheet that has been subjected to the folding process by thefolding processing unit3 and then is conveyed in thepost-processing unit4. Furthermore, thededicated device80 is a scanning device that scans an image being displayed on a plane of paper in thescanner unit5.
• In this hardware configuration, a software control unit is configured such that a program stored in a storage medium such as theROM30, theHDD40, or an optical disk (not illustrated) is read out to theRAM20, and theCPU10 performs an operation according to the program loaded onto theRAM20. Functional blocks of implementing a function of theimage forming apparatus1 according to the present embodiment is configured with a combination of the software control unit and the hardware configured as described above.
• Next, a functional configuration of theimage forming apparatus1 according to the present embodiment will be described with reference toFIG. 4.FIG. 4 is a block diagram schematically illustrating a functional configuration of theimage forming apparatus1 according to the present embodiment. InFIG. 4, an electrical connection is indicated by a solid line arrow, and the flow of a bundle of sheets or documents is indicated by a dotted line arrow.
• Theimage forming apparatus1 according to the present embodiment includes acontroller100, a sheet feeding table110, aprint engine120, afolding processing engine130, apost-processing engine140, ascanner engine150, an Auto Document Feeder (ADF)160, asheet discharge tray170, adisplay panel180, and a network I/F190 as illustrated inFIG. 4. Further, thecontroller100 includes amain control unit101, anengine control unit102, an I/O control unit103, animage processing unit104, and an operationdisplay control unit105.
• The sheet feeding table110 feeds the sheet to theprint engine120 serving as an image forming unit. Theprint engine120 is an image forming unit with which theimage forming unit2 is equipped, and renders an image by performing an image forming output on the sheet conveyed from the sheet feeding table110. As a specific example of theprint engine120, an image forming mechanism employing an inkjet scheme, an image forming mechanism employing an electrophotography scheme, or the like may be used. The image-formed sheet which has been subjected to the image rendered by theprint engine120 is conveyed to thefolding processing unit3 or discharged to thesheet discharge tray170.
• Thefolding processing engine130 is arranged in thefolding processing unit3, and performs the folding process on the image-formed sheet conveyed from theimage forming unit2. The folded sheet that has been subjected to the folding process by thefolding processing engine130 is conveyed to thepost-processing unit4. Thepost-processing engine140 is arranged in thepost-processing unit4, and performs post processing such as stapling, punching, and binding on the folded sheet conveyed from thefolding processing engine130. The sheet that has been subjected to the post processing by thepost-processing engine140 is discharged to thesheet discharge tray170.
• TheADF160 is arranged in thescanner unit5, and automatically conveys an original to thescanner engine150 serving as an original scanning unit. Thescanner engine150 is arranged in thescanner unit5, and is an original scanning unit including a photoelectric conversion element that converts optical information into an electrical signal, and generates image information by optically scanning an original automatically conveyed by theADF160 or an original set on a platen glass (not illustrated). The original that is automatically conveyed by theADF160 and scanned by thescanner engine150 is discharged to the sheet discharge tray installed in theADF160.
• Thedisplay panel180 is not only an output interface that visually displays the state of theimage forming apparatus1 but also an input interface serving as a touch panel that enables the user to directly operate theimage forming apparatus1 or input information to theimage forming apparatus1. In other words, thedisplay panel180 has a function of displaying an image used to receive an operation performed by the user. Thedisplay panel180 is implemented by theLCD60 and the operatingunit70 ofFIG. 3.
• The network I/F190 is an interface that enables theimage forming apparatus1 to communicate with other devices such as an administrator terminal via a network, and an interface such as Ethernet (a registered trademark), a Universal Serial Bus (USB) interface, Bluetooth (a registered trademark), Wireless Fidelity (Wi-Fi), FeliCa (a registered trademark), or the like is used. The network I/F190 is implemented by the I/F50 illustrated inFIG. 3.
• Thecontroller100 is configured with a combination of software and hardware. Specifically, thecontroller100 is configured with hardware such as an integrated circuit (IC) and a software control unit that is configured such that a control program such as firmware stored in a non-volatile storage medium such as theROM30 or theHDD40 is loaded onto theRAM20, and theCPU10 performs an operation according to the program. Thecontroller100 functions as a control unit that controls theimage forming apparatus1 in general.
• Themain control unit101 plays a role to control the respective units included in thecontroller100, and gives a command to the respective units of thecontroller100. Further, themain control unit101 controls the I/O control unit103, and accesses other devices through the network I/F190 and the network. Theengine control unit102 controls or drives a driving unit such as theprint engine120, thefolding processing engine130, thepost-processing engine140, or thescanner engine150. The I/O control unit103 inputs a signal or a command input through the network I/F190 and the network to themain control unit101.
• Theimage processing unit104 generates rendering information based on document data or image data included in an input print job according to control of themain control unit101. The rendering information is data such as bitmap data of CMYK and refers to information used when theprint engine120 serving as the image forming unit renders an image to be formed in the image forming operation. Further, theimage processing unit104 processes imaging data input from thescanner engine150, and generates image data. The image data refers to information that is stored in theimage forming apparatus1 as a result of the scanner operation or transmitted to another device through the network I/F190 and the network. The operationdisplay control unit105 causes thedisplay panel180 to perform an information display or notifies themain control unit101 of information input through thedisplay panel180.
• Next, an internal structure of thefolding processing unit3 according to the present embodiment will be described with reference toFIG. 5.FIG. 5 is a cross-sectional view illustrating thefolding processing unit3 according to the present embodiment when viewed in the direction perpendicular to the sheet conveyance direction.
• Thefolding processing unit3 according to the present embodiment includes an entrance conveyingroller pair310, aregistration roller pair320, a first forward-reverserotating roller pair330, a first foldingprocessing roller pair340, a second forward-reverserotating roller pair350, a second foldingprocessing roller pair360, a dischargingroller pair370, afirst sensor381, asecond sensor382, and athird sensor383 as illustrated inFIG. 5.
• The entrance conveyingroller pair310 is rotationally driven by an entrance conveying rollerpair drive motor310a,receives an image-formed sheet conveyed from theimage forming unit2, and conveys the sheet toward theregistration roller pair320.
• Theregistration roller pair320 is rotationally driven by a registration rollerpair drive motor320a, performs registration correction on the sheet by stopping rotation by a certain period of time in a state in which a leading edge of the sheet conveyed from the entrance conveyingroller pair310 abuts on a nip portion, and conveys the sheet toward the first forward-reverserotating roller pair330 or the first foldingprocessing roller pair340.
• The first forward-reverserotating roller pair330 is rotationally driven by a first forward-reverse rotating rollerpair drive motor330a,and a rotation direction of the first forward-reverserotating roller pair330 is reversed as necessary.
• One roller of the first foldingprocessing roller pair340 also serves as one first forward-reverserotating roller331 of the first forward-reverserotating roller pair330, and the first foldingprocessing roller pair340 is rotationally driven by the first forward-reverse rotating rollerpair drive motor330athrough the first forward-reverserotating roller331. Thus, the rotation direction of the first foldingprocessing roller pair340 is reversed at the first forward-reverserotating roller pair330. Hereinafter, one roller of the first foldingprocessing roller pair340 that does not serve as the first forward-reverserotating roller331 is referred to as a “firstfolding processing roller341.”
• The second forward-reverserotating roller pair350 is rotationally driven by a second forward-reverse rotating rollerpair drive motor350a,and a rotation direction of the second forward-reverserotating roller pair350 is reversed as necessary.
• One roller of the second foldingprocessing roller pair360 also serves as one first forward-reverserotating roller331 of the first forward-reverserotating roller pair330, and the second foldingprocessing roller pair360 is rotationally driven by the first forward-reverse rotating rollerpair drive motor330athrough the first forward-reverserotating roller331. Thus, the rotation direction of the second foldingprocessing roller pair360 is reversed at the first forward-reverserotating roller pair330. Hereinafter, one roller of the second foldingprocessing roller pair360 that does not serve as the first forward-reverserotating roller331 is referred to as a “secondfolding processing roller361.” In other words, in the present embodiment, each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 functions as any one of a first folding roller, a second folding roller, and a third folding roller.
• The dischargingroller pair370 is rotationally driven by a discharging rollerpair drive motor370a,conveys the sheet to thepost-processing unit4 or discharges the sheet to thesheet discharge tray170.
• Thefirst sensor381 detects the leading edge of the sheet conveyed from theimage forming unit2 in the conveyance direction. When the leading edge of the sheet in the conveyance direction is detected by thefirst sensor381, thefolding processing unit3 according to the present embodiment causes the entrance conveyingroller pair310 to start rotating.
• Thesecond sensor382 detects the leading edge of the sheet conveyed from the first forward-reverserotating roller pair330 in the conveyance direction. Thefolding processing unit3 according to the present embodiment reverses the rotation direction of the first forward-reverserotating roller pair330 at a point in time at which the sheet is conveyed by a certain distance S1 after the leading edge of the sheet is detected by thesecond sensor382.
• Thethird sensor383 detects the leading edge of the sheet conveyed from the second forward-reverserotating roller pair350 in the conveyance direction. Thefolding processing unit3 according to the present embodiment reverses the rotation direction of the second forward-reverserotating roller pair350 at a point in time at which the sheet is conveyed by a certain distance S2 after the leading edge of the sheet is detected by thethird sensor383.
• Here, thefolding processing unit3 according to the present embodiment decides the distances S1 and S2 based on a size and a folding method of the sheet. Thus, it is necessary to store the different distances S1 and S2 according to the size and the folding method of the sheet in thefolding processing unit3 according to the present embodiment. Further, thefolding processing unit3 according to the present embodiment determines whether or not the sheet has been actually conveyed by the distance S1 based on a rotation amount of the first forward-reverserotating roller pair330, and determines whether or not the sheet has been actually conveyed by the distance S2 based on a rotation amount of the second forward-reverserotating roller pair350.
• Next, an exemplary operation when thefolding processing unit3 according to the present embodiment performs the folding process will be described with reference toFIGS. 6A to 8C.FIGS. 6A to 8C are cross-sectional views illustrating thefolding processing unit3 performing the folding processing operation in theimage forming apparatus1 according to the present embodiment when viewed in the direction perpendicular to the sheet conveyance direction. Here, an operation of each operating unit described below is performed by control of themain control unit101 and theengine control unit102.FIGS. 6A to 8C illustrate an exemplary operation when thefolding processing unit3 according to the present embodiment performs Z folding on the sheet.
• In order to perform the folding processing operation through thefolding processing unit3 of theimage forming apparatus1 according to the present embodiment, when asheet6 is conveyed from theimage forming unit2, and the leading edge of thesheet6 in the conveyance direction is detected by thefirst sensor381 as illustrated inFIG. 6A, the entrance conveyingroller pair310 starts to rotate, the image-formedsheet6 conveyed from theimage forming unit2 is received by the entrance conveyingroller pair310, and thesheet6 is conveyed toward theregistration roller pair320.
• Then, thefolding processing unit3 performs the registration correction on the image-formedsheet6 conveyed by the entrance conveyingroller pair310 through theregistration roller pair320, and then conveys thesheet6 toward an upstream side in the conveyance direction through the first forward-reverserotating roller pair330 as illustrated inFIG. 6B.
• Thereafter, when thesheet6 is conveyed by the certain distance S1 after the leading edge of thesheet6 in the conveyance direction is detected by thesecond sensor382, thefolding processing unit3 causes a first folding position of thesheet6 to be bent to the first foldingprocessing roller pair340 side so that a position of a formed bend does not deviate by reversing the rotation direction of the first forward-reverserotating roller pair330, and guides the bend to the nip portion of the first foldingprocessing roller pair340 by further conveying thesheet6 as illustrated inFIG. 6C.
• Then, thefolding processing unit3 forms a folding line at the first folding position by pinching the bend formed on thesheet6 from both surfaces at the nip portion of the first foldingprocessing roller pair340 as illustrated inFIG. 7A, and conveys thesheet6 toward the second forward-reverserotating roller pair350 and further conveys thesheet6 to the upstream side in the conveyance direction as illustrated inFIGS. 7B and 7C.
• Thereafter, when thesheet6 is conveyed by the certain distance S2 after the leading edge of thesheet6 in the conveyance direction is detected by thethird sensor383, thefolding processing unit3 causes a second folding position of thesheet6 to be bent to the second foldingprocessing roller pair360 side so that the position of the formed bend does not deviate by reversing the rotation direction of the second forward-reverserotating roller pair350, and guides the bend to the nip portion of the second foldingprocessing roller pair360 by further conveying thesheet6 as illustrated inFIG. 8A.
• Then, thefolding processing unit3 forms a folding line at the second folding position by pinching the bend formed on thesheet6 from both surfaces at the nip portion of the second foldingprocessing roller pair360, and conveys thesheet6 toward the dischargingroller pair370 as illustrated inFIG. 8B.
• Thereafter, thefolding processing unit3 conveys thesheet6 to thepost-processing unit4 through the dischargingroller pair370 or discharges thesheet6 to thesheet discharge tray170 as illustrated inFIG. 8C.
• As a result of the operation illustrated inFIGS. 6A to 8C, thesheet6 becomes a state in which the Z folding has been performed as illustrated inFIG. 9.
• The exemplary operation when thefolding processing unit3 performs the Z folding on thesheet6 has been described with reference toFIGS. 6A to 8C. Besides, thefolding processing unit3 can also perform inside triple folding on thesheet6 through an operation illustrated inFIGS. 10A to 12C. As a result of the operation illustrated inFIGS. 10A to 12C, thesheet6 becomes a state in which the inside triple folding has been performed as illustrated inFIG. 13.
• Besides, thefolding processing unit3 can also perform outside triple folding on thesheet6 through an operation illustrated inFIGS. 14A to 16C. As a result of the operation illustrated inFIGS. 14A to 16C, thesheet6 becomes a state in which outside triple folding has been performed as illustrated inFIG. 17.
• This operation is the same as the operation described with reference toFIGS. 6A to 8C, but the distances S1 and S2 differ in each operation. Thus, thefolding processing unit3 causes timings at which the rotation directions of the first forward-reverserotating roller pair330 and the second forward-reverserotating roller pair350 are reversed to differ in each operation.
• Further, in addition to the above folding methods, thefolding processing unit3 according to the present embodiment can also perform folding methods illustrated inFIGS. 18A and 18B by changing an operation according to a folding method.
• Next, structures of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 in thefolding processing unit3 according to the present embodiment will be described with reference toFIGS. 19 to 21.FIG. 19 is a perspective view illustrating the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 in thefolding processing unit3 according to the present embodiment.FIG. 20 is a perspective view illustrating the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 in thefolding processing unit3 according to the present embodiment that are cut in a central portion in a direction perpendicular to a sheet conveyance direction.FIG. 21 is a cross-sectional view illustrating the central portion of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 in the direction perpendicular to the sheet conveyance direction in thefolding processing unit3 according to the present embodiment when viewed in the direction perpendicular to the sheet conveyance direction.
• As illustrated inFIG. 19, the first forward-reverserotating roller331 according to the present embodiment is configured with six rollers, that is, a first forward-reverserotating roller331a,a first forward-reverserotating roller331b,a first forward-reverserotating roller331c,a first forward-reverserotating roller331d, a first forward-reverserotating roller331e,and a first forward-reverserotating roller331fhaving the same size, shape, and structure.
• The firstfolding processing roller341 according to the present embodiment is configured with six rollers, that is, a firstfolding processing roller341a,a firstfolding processing roller341b,a firstfolding processing roller341c,a firstfolding processing roller341d,a firstfolding processing roller341e,and a firstfolding processing roller341fhaving the same size, shape, and structure.
• The secondfolding processing roller361 according to the present embodiment is configured with six rollers, that is, a secondfolding processing roller361a,a secondfolding processing roller361b,a secondfolding processing roller361c,a secondfolding processing roller361d,a secondfolding processing roller361e,and a secondfolding processing roller361fhaving the same size, shape, and structure.
• Since each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 according to the present embodiment is configured with a plurality of rollers having the same size, shape, and structure as described above, it is possible to reduce the manufacturing cost of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361. Here, each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 is configured with the same type of rollers having the same size, shape, and structure, but it is possible to further reduce the manufacturing cost of each roller by using a common type of roller between rollers.
• In the first forward-reverserotating roller331 according to the present embodiment, gaps are formed in the revolving direction at three positions, that is, between the first forward-reverserotating roller331band the first forward-reverserotating roller331c,between the first forward-reverserotating roller331cand the first forward-reverserotating roller331d,and between the first forward-reverserotating roller331dand the first forward-reverserotating roller331e.
• In the firstfolding processing roller341 according to the present embodiment, gaps are formed in the revolving direction at three positions, that is, between the firstfolding processing roller341aand the firstfolding processing roller341b,between the firstfolding processing roller341cand the firstfolding processing roller341d,and between the firstfolding processing roller341eand the firstfolding processing roller341f.
• In the secondfolding processing roller361 according to the present embodiment, gaps are formed in the revolving direction at three positions, that is, between the secondfolding processing roller361aand the secondfolding processing roller361b,between the secondfolding processing roller361cand the secondfolding processing roller361d,and between the secondfolding processing roller361eand the secondfolding processing roller361f.
• The gap is formed in the revolving direction between the configured rollers in each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 according to the present embodiment as described above, and thus it is possible to prevent the folding quality from being lowered because a sheet is misdirected and so a wrinkle or a skew occurs or a folding position is deviated. Here, in this configuration, there is a portion that is not pressed due to the gap formed in the firstfolding processing roller341. In this regard, the position of the gap formed in the firstfolding processing roller341 in the direction perpendicular to the sheet conveyance direction is adjusted to be different from the position of the gap formed in the secondfolding processing roller361 in the direction perpendicular to the sheet conveyance direction, and thus the portion that is not pressed due to the gap is pressed by the second foldingprocessing roller pair360, and thus a folding line can be formed effectively.
• The first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 having the above configuration are fixed such that a first forward-reverserotating roller bearing333, a first foldingprocessing roller bearing343, and a second foldingprocessing roller bearing363 are supported by shaft holes formed in asupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction and laterally bridged in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 20. Here,FIG. 20 illustrates only one end in the direction perpendicular to the sheet conveyance direction, and the other end is similarly fixed. In other words, in the present embodiment, thesupport plate390 and a support plate arranged at the position opposite to thesupport plate390 function as a support unit.
• Further, in the firstfolding processing roller341 according to the present embodiment, a groove is formed in the revolving direction between the firstfolding processing roller341cand the firstfolding processing roller341d,that is, in the central portion in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 20. Further, in the firstfolding processing roller341 according to the present embodiment, abearing344 is mounted in the groove to slide on an outer circumference of a first folding processingroller rotating shaft342 serving as a rotating shaft of the firstfolding processing roller341 as illustrated inFIG. 20. A first folding processingroller pressing member345 fixed to a first folding processing roller pressingmember fixing stay346 is mounted on thebearing344 to grip the outer circumference of thebearing344.
• Here, a state in which the first folding processing roller pressingmember fixing stay346 is fixed to thesupport plate390 according to the present embodiment will be described with reference toFIG. 22.FIG. 22 is a diagram for describing a state in which the first folding processing roller pressingmember fixing stay346 is fixed to thesupport plate390 according to the present embodiment.
• The first folding processing roller pressingmember fixing stay346 according to the present embodiment includes aninsertion portion346aformed at one end thereof in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 22. Theinsertion portion346ais configured to taper such that a width L1 of a leading edge is smaller than a width L2 of a body portion. The first folding processing roller pressingmember fixing stay346 according to the present embodiment further includes a fixingportion346bformed at the other end in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 19. Further, aninsertion hole391 having a width L3 satisfying L1<L3<L2 is formed in thesupport plate390.
• In the first folding processing roller pressingmember fixing stay346 according to the present embodiment, the fixingportion346bof the other end is fixed to thesupport plate390 installed at the side opposite to thesupport plate390 by a screw in the state in which theinsertion portion346ais inserted into theinsertion hole391. Thus, the first folding processing roller pressingmember fixing stay346 according to the present embodiment is fixed such that the first folding processing roller pressingmember fixing stay346 is supported by thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction and laterally bridged in the direction perpendicular to the sheet conveyance direction.
• As the first folding processing roller pressingmember fixing stay346 is fixed as described above, the first folding processingroller pressing member345 applies force N1 toward the rotational center of the first forward-reverserotating roller331 through the first folding processing roller pressingmember fixing stay346 as illustrated inFIG. 21. Thus, the first folding processingroller pressing member345 firmly presses the firstfolding processing roller341 against the first forward-reverserotating roller331 through thebearing344 and the first folding processingroller rotating shaft342 by the force N1.
• Here, as illustrated inFIG. 22, in the first folding processing roller pressingmember fixing stay346 according to the present embodiment, theinsertion portion346ais formed at one end in the direction perpendicular to the sheet conveyance direction, theinsertion portion346ais configured to taper, and the width L1 of the leading edge is smaller than the width L2 of the body portion. Thus, in thefolding processing unit3 according to the present embodiment, it is possible to adjust the magnitude of the force N1 by adjusting the length in which theinsertion portion346ais inserted into theinsertion hole391.
• At this time, since the first forward-reverserotating roller331 and the firstfolding processing roller341 are fixed to thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction as described above, the firstfolding processing roller341 and the first forward-reverserotating roller331 are pressed firmly by uniform force acting over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can press the sheet from the sheet surfaces in the nip portion between the first forward-reverserotating roller331 and the firstfolding processing roller341 by uniform pressing force acting over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can effectively form a folding line even on a sheet in which the width in the direction perpendicular to the sheet conveyance direction is large over the whole area of the sheet.
• Similarly to the firstfolding processing roller341, the secondfolding processing roller361 according to the present embodiment is configured to apply force of firmly pressing the secondfolding processing roller361 against the first forward-reverserotating roller331 in the central portion of the secondfolding processing roller361.
• Specifically, in the secondfolding processing roller361 according to the present embodiment, the groove is formed in the revolving direction between the secondfolding processing roller361cand the secondfolding processing roller361d,that is, in the central portion in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 20. Further, as illustrated inFIG. 20, in the secondfolding processing roller361 according to the present embodiment, abearing364 is mounted in the groove to slide on an outer circumference of a second folding processingroller rotating shaft362 serving as a rotating shaft of the secondfolding processing roller361 as illustrated inFIG. 20. A second folding processingroller pressing member365 fixed to a second folding processing roller pressingmember fixing stay366 is mounted on thebearing364 to grip the outer circumference of thebearing364.
• A second folding processingroller pressing member365 has a similar configuration to that of the first folding processingroller pressing member345 described with reference toFIG. 21. Similarly to the first folding processing roller pressingmember fixing stay346 described above with reference toFIG. 22, the second folding processing roller pressingmember fixing stay366 according to the present embodiment is fixed such that the second folding processing roller pressingmember fixing stay366 is supported by thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction and laterally bridged in the direction perpendicular to the sheet conveyance direction.
• As the second folding processing roller pressingmember fixing stay366 is fixed as described above, the second folding processingroller pressing member365 applies force N2 toward the rotational center of the first forward-reverserotating roller331 through the second folding processing roller pressingmember fixing stay366 as illustrated inFIG. 21. Thus, the second folding processingroller pressing member365 firmly presses the secondfolding processing roller361 against the first forward-reverserotating roller331 through thebearing364 and the second folding processingroller rotating shaft362 by the force N2.
• Here, as described above, the second folding processing roller pressingmember fixing stay366 according to the present embodiment has a similar configuration to that of the first folding processing roller pressingmember fixing stay346. Thus, in thefolding processing unit3 according to the present embodiment, it is possible to adjust the magnitude of the force N2 by adjusting the length in which the second folding processing roller pressingmember fixing stay366 is inserted into the insertion hole.
• At this time, since the first forward-reverserotating roller331 and the secondfolding processing roller361 are fixed to thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction as described above, the secondfolding processing roller361 and the first forward-reverserotating roller331 are pressed firmly by uniform force acting over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can press the sheet from the sheet surfaces in the nip portion between the first forward-reverserotating roller331 and the secondfolding processing roller361 by uniform pressing force acting over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can effectively form a folding line even on a sheet in which the width in the direction perpendicular to the sheet conveyance direction is large over the whole area of the sheet.
• As one of the gists, as described above, thefolding processing unit3 according to the present embodiment applies force of firmly pressing the firstfolding processing roller341 against the first forward-reverserotating roller331 in the central portion of the firstfolding processing roller341, and applies force of firmly pressing the secondfolding processing roller361 against the first forward-reverserotating roller331 in the central portion of the secondfolding processing roller361. As a result, thefolding processing unit3 according to the present embodiment can generate sufficient pressing force evenly over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can form a folding line on a sheet effectively and improve a folding quality.
• Here, the present embodiment has been described in connection with the example in which the first folding processingroller pressing member345 is mounted to the first folding processingroller rotating shaft342 of the firstfolding processing roller341 through the bearing344 to slide on the outer circumference of the first folding processingroller rotating shaft342, but the first folding processingroller pressing member345 may be mounted directly to the first folding processingroller rotating shaft342.
• In the case of this configuration, when the force N1 is applied from the first folding processingroller pressing member345 toward a first forward-reverse rotatingroller rotating shaft332, the rotation of the firstfolding processing roller341 is hindered by friction in a contact portion between the first folding processingroller rotating shaft342 and the first folding processingroller pressing member345, and the contact portion between the first folding processingroller rotating shaft342 and the first folding processingroller pressing member345 is worn.
• In this regard, in the firstfolding processing roller341 according to the present embodiment, thebearing344 is mounted to the first folding processingroller rotating shaft342 to slide on the outer circumference of the first folding processingroller rotating shaft342, and thus the above problem can be prevented.
• Similarly, the present embodiment has been described in connection with the example in which the second folding processingroller pressing member365 is mounted to the second folding processingroller rotating shaft362 of the secondfolding processing roller361 through the bearing364 to slide on the outer circumference of the second folding processingroller rotating shaft362, but the second folding processingroller pressing member365 may be mounted directly to the second folding processingroller rotating shaft362.
• In the case of this configuration, when the force N2 is applied from the second folding processingroller pressing member365 toward the first forward-reverse rotatingroller rotating shaft332, the rotation of the secondfolding processing roller361 is hindered by friction in a contact portion between the second folding processingroller rotating shaft362 and the second folding processingroller pressing member365, and the contact portion between the second folding processingroller rotating shaft362 and the second folding processingroller pressing member365 is worn.
• In this regard, in the secondfolding processing roller361 according to the present embodiment, thebearing364 is mounted to the second folding processingroller rotating shaft362 to slide on the outer circumference of the second folding processingroller rotating shaft362, and thus the above problem can be prevented.
• Here, effects of thefolding processing unit3 according to the present embodiment will be described in detail with reference toFIGS. 23 and 24.FIG. 23 is a diagram illustrating a pressing force distribution in the direction perpendicular to the sheet conveyance direction when thefolding processing unit3 according to the related art presses the sheet through the folding processing roller pair.FIG. 24 is a diagram illustrating a pressing force distribution in the direction perpendicular to the sheet conveyance direction when thefolding processing unit3 according to the present embodiment presses the sheet through the first foldingprocessing roller pair340 or the second foldingprocessing roller pair360.
• The folding processing unit according to the related art is configured to cause force for pressing the two folding processing rollers configuring the folding processing roller pair against each other to act on both ends in the direction perpendicular to the sheet conveyance direction.
• Thus, in the folding processing unit according to the related art, the repulsive force is generated from the sheet being pressed against the folding processing roller, but since force for pressing the folding processing rollers against each other acts on near both ends in the direction perpendicular to the sheet conveyance direction, it is possible to counter the repulsive force. On the other hand, in the folding processing unit according to the related art, since force countering the repulsive force does not act on near the central portion in the direction perpendicular to the sheet conveyance direction, a portion near the central portion of the folding processing roller is bent in a direction opposite to the pressing direction.
• Thus, as illustrated inFIG. 23, in the folding processing unit according to the related art, it is possible to secure sufficient pressing force near both ends in the direction perpendicular to the sheet conveyance direction, but it is difficult to secure sufficient pressing force near the central portion. As a result, in the folding processing unit according to the related art, it is difficult to effectively press the sheet near the central portion in the direction perpendicular to the sheet conveyance direction.
• Further, in the folding processing unit according to the related art, since the force for pressing the folding processing rollers against each other is caused to act on both ends of the folding processing roller pair in the direction perpendicular to the sheet conveyance direction, a deviation of the pressing force occurs between both ends as illustrated inFIG. 23. As a result, in the folding processing unit according to the related art, a wrinkle or a skew occurs in the sheet, or the folding position is misaligned, resulting in a reduction in a folding quality.
• In this regard, thefolding processing unit3 according to the present embodiment is configured so that force for pressing the firstfolding processing roller341 against the first forward-reverserotating roller331 acts on the central portion of the firstfolding processing roller341, and force for pressing the secondfolding processing roller361 against the first forward-reverserotating roller331 acts on the central portion of the secondfolding processing roller361. In other words, in the present embodiment, each of the first folding processingroller pressing member345 and the second folding processingroller pressing member365 functions as any one of the first pressing unit and the second pressing unit.
• Thus, thefolding processing unit3 according to the present embodiment can implement a pressing force distribution that is line-symmetric in the central portion by generating strongest pressing force in the central portion in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 24. As a result, thefolding processing unit3 according to the present embodiment can generate appropriate pressing force evenly over the whole area in the direction perpendicular to the sheet conveyance direction. Thus, thefolding processing unit3 according to the present embodiment can form a folding line on a sheet effectively and improve a folding quality.
• Here, the present embodiment has been described in connection with the example in which the firstfolding processing roller341 and the secondfolding processing roller361 are fixed such that, as illustrated inFIG. 20, the first foldingprocessing roller bearing343 and the second foldingprocessing roller bearing363 are supported by the shaft holes formed in thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction and laterally bridged in the direction perpendicular to the sheet conveyance direction as described above with reference toFIG. 20. Besides, the shaft holes formed in thesupport plate390 to support the firstfolding processing roller341 and the secondfolding processing roller361 may be formed as an elliptical shape that is long in the direction in which the first forward-reverserotating roller331 is pressed as illustrated inFIG. 25. Through this configuration, the firstfolding processing roller341 and the secondfolding processing roller361 are movable.
• In the case of this configuration, the firstfolding processing roller341 and the secondfolding processing roller361 are firmly pressed against the first forward-reverserotating roller331 in a state in which the first folding processing roller pressingmember fixing stay346 and the second folding processing roller pressingmember fixing stay366 are fixed to thesupport plate390. On the other hand, the firstfolding processing roller341 and the secondfolding processing roller361 are separated from the first forward-reverserotating roller331 in a state in which the first folding processing roller pressingmember fixing stay346 and the second folding processing roller pressingmember fixing stay366 are removed from thesupport plate390. Here,FIG. 25 illustrates only one end in the direction perpendicular to the sheet conveyance direction, and the other end is similarly fixed.
• Further, the present embodiment has been described in connection with the example in which the first folding processingroller pressing member345 and the second folding processingroller pressing member365 are mounted to the firstfolding processing roller341 and the secondfolding processing roller361, respectively, and the firstfolding processing roller341 and the secondfolding processing roller361 are firmly pressed against the first forward-reverserotating roller331 by the force N1 and the force N2 as described above with reference toFIG. 21.
• Besides, as illustrated inFIG. 26, a first forward-reverse rotatingroller pressing member335 may be mounted to the first forward-reverserotating roller331 instead of the firstfolding processing roller341 and the secondfolding processing roller361.FIG. 26 is a cross-sectional view illustrating the central portion of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 in the direction perpendicular to the sheet conveyance direction in thefolding processing unit3 according to the present embodiment when viewed in the direction perpendicular to the sheet conveyance direction.
• Specifically, in the first forward-reverserotating roller331 according to the present embodiment, a groove is formed in the revolving direction between the first forward-reverserotating roller331cand the first forward-reverserotating roller331d,that is, in the central portion in the direction perpendicular to the sheet conveyance direction as illustrated inFIG. 26,. Further, in the first forward-reverserotating roller331 according to the present embodiment, abearing334 is mounted in the groove to slide on the outer circumference of the first forward-reverse rotatingroller rotating shaft332 serving as the rotating shaft of the first forward-reverserotating roller331 as illustrated inFIG. 26. A first forward-reverse rotatingroller pressing member335 fixed to a first forward-reverse rotating roller pressing member fixing stay336 is mounted on thebearing334 to grip the outer circumference of thebearing334.
• The first forward-reverse rotating roller pressing member fixing stay336 has a similar configuration to that of the first folding processing roller pressingmember fixing stay346 as described above with reference toFIG. 22. Further, similarly to the first folding processing roller pressingmember fixing stay346, the first forward-reverse rotatingroller pressing member335 according to the present embodiment is fixed such that the first forward-reverse rotatingroller pressing member335 is supported by thesupport plate390 installed vertically to both ends in the direction perpendicular to the sheet conveyance direction and laterally bridged in the direction perpendicular to the sheet conveyance direction as described above with reference toFIG. 22. In other words, in the present embodiment, any one of the first forward-reverse rotating roller pressing member fixing stay336, the first folding processing roller pressingmember fixing stay346, and the second folding processing roller pressingmember fixing stay366 functions as a pressing/fixing unit.
• As the first forward-reverse rotating roller pressing member fixing stay336 is fixed as described above, the first forward-reverse rotatingroller pressing member335 causes force N3 to act in a direction orthogonal to a line segment connecting the rotational center of the firstfolding processing roller341 with the rotational center of the secondfolding processing roller361 through the first forward-reverse rotating roller pressing member fixing stay336 as illustrated inFIG. 26. As a result, the first forward-reverse rotatingroller pressing member335 causes force Na serving as partial pressure of the force N3 to act in the rotational center of the firstfolding processing roller341, and causes force Nb serving as partial pressure of the force N3 to act in the rotational center of the secondfolding processing roller361 as illustrated in FIG.26.
• Thus, the first forward-reverse rotatingroller pressing member335 firmly presses against the first forward-reverserotating roller331 against the firstfolding processing roller341 and the secondfolding processing roller361 through thebearing334 and the first forward-reverse rotatingroller rotating shaft332 by the force Na and the force Nb. In the case of this configuration, the mechanism for firmly pressing the first forward-reverserotating roller331 and the firstfolding processing roller341 and the mechanism for firmly pressing the first forward-reverserotating roller331 and the secondfolding processing roller361 need not be separately equipped, and thus the number of parts can be reduced. Accordingly, it is possible to simply configure thefolding processing unit3 at a low cost.
• Further, the present embodiment has been described in connection with the example in which each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 is configured with a plurality of rollers having the same size, shape, and structure as described above with reference toFIG. 19, but each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 may be configured with a plurality of types of rollers. A specific example of this configuration will be described with reference toFIG. 27.FIG. 27 is a perspective view illustrating the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 of thefolding processing unit3 according to the present embodiment.
• The first forward-reverserotating roller331 according to the present embodiment is configured with two types of rollers as illustrated inFIG. 27. In other words, in the first forward-reverserotating roller331 according to the present embodiment, the first forward-reverserotating roller331aand the first forward-reverserotating roller331dhave the same size, shape, and structure. Further, in the first forward-reverserotating roller331 according to the present embodiment, the first forward-reverserotating roller331band the first forward-reverserotating roller331chave the same size, shape, and structure, but have a size, shape, and structure different from the first forward-reverserotating roller331aand the first forward-reverserotating roller331d.The same applies to the firstfolding processing roller341 and the secondfolding processing roller361 according to the present embodiment as illustrated inFIG. 27.
• Even in the case of this configuration, it is possible to reduce the manufacturing cost of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361. Here, each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 is configured with two types of rollers, but the manufacturing cost of each roller can be further reduced by using a common type of roller between rollers.
• Further, the present embodiment has been described in connection with the example in which each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 is configured with a plurality of rollers as described above with reference toFIGS. 19 and 27, but each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 may be configured with a single roller as illustrated inFIG. 28.FIG. 28 is a perspective view illustrating the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 of thefolding processing unit3 according to the present embodiment. In the case of this configuration, the manufacturing cost of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 tends to increase to be higher than when each of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361 is configured with a plurality of rollers, but the other effects can be obtained, similarly to the effects of the present embodiment.
• Here, since the first folding processingroller pressing member345 and the second folding processingroller pressing member365 are mounted on the firstfolding processing roller341 and the secondfolding processing roller361 in the central portion in the direction perpendicular to the sheet conveyance direction, the first folding processingroller pressing member345 and the second folding processingroller pressing member365 are configured so that the central portion is smaller in diameter than the other portions, and mounted to grip the outer circumference of the central portion.
• Further, the present embodiment has been described in connection with the example in which the first folding processingroller pressing member345 and the second folding processingroller pressing member365 are mounted to the firstfolding processing roller341 and the secondfolding processing roller361, respectively, as described above with reference toFIG. 21, or the first forward-reverse rotatingroller pressing member335 is mounted to the first forward-reverserotating roller331 instead of the firstfolding processing roller341 and the secondfolding processing roller361 as described above with reference toFIG. 26.
• Besides, the first forward-reverse rotatingroller pressing member335, the first folding processingroller pressing member345, and the second folding processingroller pressing member365 may be mounted to all of the first forward-reverserotating roller331, the firstfolding processing roller341, and the secondfolding processing roller361, respectively, as illustrated inFIG. 29. In the case of this configuration, since it is possible to increase the pressing force, it is possible to form a folding line more effectively.
• Further, the present embodiment has been described in connection with the example in which force for firmly pressing the firstfolding processing roller341 against the first forward-reverserotating roller331 is caused to act on the central portion of the firstfolding processing roller341, and force for firmly pressing the secondfolding processing roller361 against the first forward-reverserotating roller331 is caused to act on the central portion of the secondfolding processing roller361.
• Besides, force for firmly pressing the firstfolding processing roller341 against the first forward-reverserotating roller331 may be caused to act on an arbitrary portion of the firstfolding processing roller341 in the direction perpendicular to the sheet conveyance direction, and force for firmly pressing the secondfolding processing roller361 against the first forward-reverserotating roller331 may be caused to act on an arbitrary portion of the secondfolding processing roller361 in the direction perpendicular to the sheet conveyance direction. Even in the case of this configuration, thefolding processing unit3 according to the present embodiment can generate sufficient pressing force evenly over the whole area in the direction perpendicular to the sheet conveyance direction.
• Further, the present embodiment has been described in connection with the configuration in which theimage forming apparatus1 is equipped with theimage forming unit2, thefolding processing unit3, thepost processing unit4, and thescanner unit5, but the respective units may be configured as independent different apparatuses, and an image forming system may be configured by connecting the apparatuses.
• According to the present invention, it is possible to form a folding line on a sheet effectively and improve a folding quality.
• Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Claims (21)

1. A sheet folding apparatus comprising:

a first pair of folding members configured to fold a sheet;

a first pair of conveying members configured to convey the sheet that has been folded by the first pair of folding members; and

a sheet detector configured to detect the sheet at a position downstream from the first pair of conveying members in a first sheet conveyance direction, wherein

the sheet folding apparatus is configured to convey the sheet by a distance downstream from the sheet detector in the first sheet conveyance direction after a folding line of the sheet passes through a nip of the first pair of conveying members, and stop the conveyance of the sheet.

2. The sheet folding apparatus according toclaim 1, wherein the sheet folding apparatus is configured to cause the first pair of conveying members to reverse rotation to bend a portion of the sheet between the first pair of folding members and the first pair of conveying members.

3. The sheet folding apparatus according toclaim 1, further comprising:

a second pair of folding members configured to fold the sheet that has been folded by the first pair of folding members.

4. The sheet folding apparatus according toclaim 3, wherein the second pair of folding members is configured to fold the sheet that has been folded by the first pair of folding members at a position upstream from the first pair of conveying members in the first sheet conveyance direction.

5. The sheet folding apparatus according toclaim 3, wherein one member of the first pair of folding members is a member of the second pair of folding members.

6. The sheet folding apparatus according toclaim 1, wherein the sheet folding apparatus is configured to adjust the distance based on sheet information.

7. The sheet folding apparatus according toclaim 6, wherein the sheet information includes a thickness of the sheet, a type of the sheet or both the thickness of the sheet and the type of the sheet.

8. The sheet folding apparatus according toclaim 5, wherein the one member of the first pair of folding members is a driving member.

9. The sheet folding apparatus according toclaim 8, wherein another member of the first pair of folding members is a driven member.

10. The sheet folding apparatus according toclaim 1, wherein the first pair of folding members and the first pair of conveying members are rollers.

11. The sheet folding apparatus according toclaim 1, further comprising:

a second pair of conveying members configured to convey the sheet to the first pair of folding members.

12. An image forming apparatus, comprising

a main body;

an image forming unit configured to form an image on a sheet; and

a sheet folding apparatus, the sheet folding apparatus being in the main body and including,

a first pair of folding members configured to fold the sheet,

a first pair of conveying members configured to convey the sheet that has been folded by the first pair of folding members, and

a sheet detector configured to detect the sheet at a position downstream from the first pair of conveying members in a first sheet conveyance direction, wherein

the sheet folding apparatus is configured to convey the sheet by a distance downstream from the sheet detector in the first sheet conveyance direction after a folding line of the sheet passes through a nip of the first pair of conveying members, and stop the conveyance of the sheet.

13. The image forming apparatus according toclaim 12, wherein the first pair of folding members and the first pair of conveying members are rollers.

14. The image forming apparatus according toclaim 12, further comprising:

a second pair of conveying members configured to convey the sheet to the first pair of folding members.

15. The image forming apparatus according toclaim 12, wherein the sheet folding apparatus is configured to cause the first pair of conveying members to reverse rotation to bend a portion of the sheet between the first pair of folding members and the first pair of conveying members.

16. The folding apparatus according toclaim 12, further comprising:

a second pair of folding members configured to fold the sheet that has been folded by the first pair of folding members.

17. An image forming system, comprising:

an image forming apparatus configured to form an image on a sheet; and

a sheet folding apparatus, the sheet folding apparatus being separate from the image forming apparatus and including,

a first pair of folding members configured to fold the sheet,

a first pair of conveying members configured to convey the sheet that has been folded by the first pair of folding members, and

a sheet detector configured to detect the sheet at a position downstream from the first pair of conveying members in a first sheet conveyance direction, wherein

the sheet folding apparatus is configured to convey the sheet by a distance downstream from the sheet detector in the first sheet conveyance direction after a folding line of the sheet passes through a nip of the first pair of conveying members, and stop the conveyance of the sheet.

18. The image forming system according toclaim 17, wherein the first pair folding members and the first pair of conveying members are rollers.

19. The image forming system according toclaim 17, further comprising:

a second pair of conveying members configured to convey the sheet to the first pair of folding members.

20. The image forming system according toclaim 17, wherein the sheet folding apparatus is configured to cause the first pair of conveying members to reverse rotation to bend a portion of the sheet between the first pair of folding members and the first pair of conveying members.

21. The image forming system according toclaim 17, further comprising:

a second pair of folding members configured to fold the sheet that has been folded by the first pair of folding members.

Images