CN102509613A - Variable capacitor and position indicator using same - Google Patents

Abstract

The invention discloses a variable capacitor. The variable capacitor comprises a capacitor case, insulating media, a first pole plate, a second pole plate and an elastic component, wherein the insulating media are arranged in the case and are provided with two opposite sides; the first pole plate is vertically arranged on one side of the insulating media; the second pole plate is vertically arranged on the other side of the insulating media and is contacted with one side of the insulating media; the elastic component is connected with the second pole plate; when the second pole plate is not under pressure, the opposite area between the first pole plate and the second pole plate is zero, thus the capacitance of the variable capacitor is zero; and when the second pole plate is under pressure, the second pole plate moves upward and compresses the elastic component to change the opposite area between the first pole plate and the second pole plate, thus changing the capacitance of the variable capacitor. The invention also discloses a position indicator using the variable capacitor. By using the variable capacitor and the position indicator, the pressure can be accurately measured.

Description

The position indicating device of variable capacitor and use variable capacitor

Technical field

The present invention relates to a kind of variable capacitor and utilize this variable capacitor to measure the position indicating device of input pressure.

Background technology

In recent years, coordinate input equipment is applied on the PC as input equipment.Coordinate input equipment comprises the position indicating device and the location detecting apparatus with inputting interface that are similar to pen; Input operation is exactly a positioning action in this equipment; Hand-written characteristic input operation or Freehandhand-drawing input operation realize that through the use location indicating device wherein device for pressure measurement is the part of position indicating device.Device for pressure measurement generally comprises variable capacitor and treatment circuit, and wherein variable capacitor comprises that an electrode that pastes mutually with insulator surface has the electrode of calibration function with another.Existing disclosed most of variable capacitor of realizing that the pen pressure is measured all is to adopt to apply certain pressure for the electrode of wherein processing with conductive rubber (electrode that promptly has calibration function); Change electrode pair over against area; Thereby change capacitance; Cause that circuit characteristic changes, and come the gaging pressure size thus.

Fig. 1 is the structure chart of variable capacitor of pressure input device of the position indicating device of prior art.As shown in Figure 1; The variable capacitor of pressure input device of the prior art comprises two electrode of opposite 3 ' and 4 ' of horizontally set; Wherein, the electrode 3 ' on top is connected with the processor (not shown) through conducting rod 2 ', and the electrode 4 ' of bottom is connected with processor through conducting rod 1 '; Electrode 4 ' is deformable, is generally processed by conductive rubber.Between two electrodes 3 ' and 4 ', be provided with dielectric 5 ', between electrode 4 ' and dielectric 5 ', also be provided withbecket 6 '.Fig. 2 is the structural representation of the pressure input device of the position indicating device of prior art when being under pressure, and in Fig. 2, when nib 8 ' was exerted pressure to electrode 4 ' through sheet metal 7 ', electrode 4 ' protruded in the becket 6 ', and contacts with dielectric 5 '.The size of pressure can change electrode pair over against area, cause the variation of capacitance, processor changes according to circuit characteristic derives the pressure size.

But there is following problem in above-mentioned prior art: at first the size of pressure can't directly obtain, and can only estimate the pressure size roughly, and this is because conductive rubber material deformation can't form strict corresponding relationship with pressure; Secondly under pressure-less state, the phenomenon of " leaking " or pen " not water outlet " can appear in nib.So-called " leaking " is meant because assembling or production technology difference, in the absence of pressure, conductive rubber electrode with pole plate between insulator contact, contact with conducting rod and constituted the variable capacitance charge-discharge circuit, thereby obtained force value; Pen " not water outlet " is meant that if nib gives certain pressure float electrode contacts with the insulator medium and do not contact with binding post, is S though have over against area, and charge-discharge circuit is not communicated with, and force value can't be measured.

Summary of the invention

For solving the problems of the technologies described above, the invention provides a kind of variable capacitor and use this variable capacitor to measure the position indicating device of input pressure.

Variable capacitor of the present invention comprises: capacitor casing; Be arranged on the dielectric in the housing, it has two relative sides; First pole plate, it vertically is arranged on a side of dielectric; Second pole plate, it vertically is arranged on the opposite side of dielectric, and touches with the flanked of dielectric; Elastomeric element, it is connected with second pole plate; Wherein, when second pole plate was not under pressure, between first pole plate and second pole plate was zero over against area, thereby the capacitance of variable capacitor is zero; When second pole plate was under pressure, it moved upward and elasticity of compression parts, with change between first pole plate and second pole plate over against area, thereby change the capacitance of variable capacitor.

In one embodiment, variable capacitor also comprises first insulation barrier that is arranged on second pole plate top; Second insulation barrier, the below that it is arranged on the bottom of capacitor casing and is positioned at second pole plate, extraneous applied pressure acts on this second insulation barrier.In this embodiment, elastomeric element is a spring, and an end of this spring is fixed on first insulation barrier, and the other end is fixed on the top inner surface of capacitor casing.

In one embodiment, variable capacitor also comprises micromatic setting, is used to adjust the position of first pole plate.

In one embodiment, when second pole plate was not under pressure, elastomeric element in the raw.

The invention also discloses a kind of position indicating device that uses above-mentioned variable capacitor, comprising: the shell that is used to grip; The variable capacitor that is used for gaging pressure, wherein, first pole plate is drawn out to outside the capacitor casing through first conducting rod, and second pole plate is drawn out to outside the capacitor casing through second conducting rod; Processor, this processor links to each other with variable capacitor with second conducting rod through first conducting rod, is used to measure discharging and recharging the time of variable capacitor.

In one embodiment, this position indicating device also comprises the nib that is arranged on outer casing end, and the one of which end is fixed on second insulation barrier of variable capacitor, and the other end extends to the outside of shell.

Variable capacitor of the present invention and the position indicating device that utilizes this variable capacitor; Adopt pressure to cause pole plate to slide; Thereby between pole plate relative position change between pole plate over against area, spring deformation be directly proportional over against area, thereby accurately obtain the size of pressure; In addition, adopt micromatic setting to regulate the position of pole plate, change between the pressure-less state bottom crown over against area, overcome the problem of " leaking " and " not water outlet ".

Description of drawings

Fig. 1 is the structural representation of the variable capacitor of prior art;

Fig. 2 is the structural representation after the variable capacitance among Fig. 1 is exerted pressure;

Fig. 3 is the structural representation of the variable capacitor of position indicating device of the present invention;

Fig. 4 is the right view of variable capacitor of the position indicating device of Fig. 3;

Fig. 5 is the structural representation after the variable capacitor of Fig. 3 is exerted pressure;

Fig. 6 is the right view of the variable capacitor among Fig. 5.

Description of reference numerals:

1 first conducting rod; 2 second conducting rods; 3 first electrodes; 4 second electrodes; 5 dielectrics; 6 capacitor casing; 7 leads; 8 nibs; 9 micromatic settings; 10 springs; 11 first insulation barriers; 12 second insulation barriers.

Embodiment

Below with accompanying drawings embodiment of the present invention.

Fig. 3 is the structural representation of the variable capacitance of pressure input device of the present invention.As shown in Figure 3, variable capacitance of the present invention comprisescapacitor casing 6, andcapacitor casing 6 inside hold each parts of variable capacitance.As shown in Figure 3, the inner bottom surfaces ofcapacitor casing 6 are provided with second insulation barrier, 12, thesecond insulation barriers 12 and are fixedly connected with nib 8 (also can be other parts that can apply power), and when nib is under pressure when mobile,second insulation barrier 12 is mobile thereupon.

The top ofsecond insulation barrier 12 is provided with dielectric 5, and the left and right sides face of dielectric 5 is respectively arranged withfirst pole plate 3 and second pole plate 4.As shown in Figure 3, two pole plates are strip, andfirst pole plate 3 vertically is arranged on a side of dielectric 5, and when no external force applied, the top of the base offirst pole plate 3 andsecond pole plate 4 just maintained an equal level.Second pole plate 4 is arranged on an other side of dielectric 5 vertically, and touches with the flanked of dielectric 5.

The other end that the top offirst pole plate 3 is connected with first conducting rod, 1, the first conductingrod 1 is exposed to outside thecapacitor casing 6, andsecond pole plate 4 is drawn out to outside thecapacitor casing 6 through second conductingrod 2, and hereinafter is introduced concrete structure in detail.

As shown in Figure 3; The top ofsecond pole plate 4 is provided withfirst insulation barrier 11; The below is provided withsecond insulation barrier 12 because second pole plate and 4 and dielectric 5 be set up in parallel, so dielectric 5 is also betweenfirst insulation barrier 11 and second insulation barrier 12.The upper surface offirst insulation barrier 11 is provided with elastomeric element (in the present embodiment, being spring 10), and an other end ofspring 10 is fixed on the top inner surface of the housing of variable capacitor, andsecond pole plate 4 can directly link to each other with second conductingrod 2 through lead.

In one embodiment; In order to reduce the connection lead in the variable capacitor; One end that can makespring 10 be fixed on the top inner surface of variable capacitor housing is connected with second conductingrod 2; Andsecond pole plate 4 is connected withspring 10 through thelead 7 that is arranged infirst insulation barrier 11, therebysecond pole plate 4 is connected with thecapacitor casing 6 second outer conductingrods 2 throughspring 10, forms the RC charge-discharge circuit.

In this execution mode, extraneous pressure affacts onsecond insulation barrier 12 throughnib 8 or miscellaneous part, and passes tosecond pole plate 4,first insulation barrier 11,spring 10 successively.

Whensecond insulation barrier 12 is not under pressure (pressure-less state),first pole plate 3 andsecond pole plate 4 just be zero over against area, andspring 10 is preferably in the raw, does not form capacitor this moment; And in casesecond insulation barrier 12 when being under pressure;Second insulation barrier 12 just promotessecond pole plate 4, dielectric 5 andfirst insulation barrier 11 to the top and moves upward, and winpole plate 3 andsecond pole plate 4 is produced over against area, thereby form variable capacitor; At this moment,spring 10 is compressed.

Preferably; Variable capacitor of the present invention also comprisesmicromatic setting 9, andmicromatic setting 9 can be fine-tuning nut or other suitable components, and it is used to change the position of first pole plate; Thereby changefirst pole plate 3 andsecond pole plate 4 over against area; Change capacitance size over against area through changing between the pole plate, discharge and recharge the time, overcome pen " leaking " and " not water outlet " problem thereby regulate under the pressure-less state.Particularly, under pressure-less state, withfirst pole plate 3 just adjust to andsecond pole plate 4 between not over against area; Shown in the right view of Fig. 4, in this case,first pole plate 3 andsecond pole plate 4 just join on vertical direction; Both do not had intersection, do not had the space yet.

Above-mentioned variable capacitor can be used in the various devices that need gaging pressure, for example coordinate indicator, electronic scale or the like.

The invention also discloses a kind of position indicating device that utilizes above-mentioned variable capacitor, it comprises the shell that is used to grip; The variable capacitor (preceding text are described in detail, do not give unnecessary details at this) that is used for the gaging pressure size; Be used to measure the processor of the time that discharges and recharges of variable capacitor, this processor links to each other with variable capacitor with second conductingrod 2 through first conductingrod 1, the discharging and recharging the time of measurement variable capacitor; Be arranged on thenib 8 of outer casing end, the one of which end is fixed onsecond insulation barrier 12 of variable capacitor, and the other end extends to the outside of shell.

Wherein, whennib 8 was not under pressure, betweenfirst pole plate 3 andsecond pole plate 4 was zero over against area, thereby made that the capacitance of variable capacitor is zero; Whennib 8 when being under pressure,nib 8 promotessecond insulation barrier 12,second pole plate 4 andfirst insulation barrier 11, and compressesspring 10 thus; Change betweenfirst pole plate 3 andsecond pole plate 4 over against area; Thereby change the capacitance of variable capacitor, at this moment, variable capacitor is as a capacitor charge and discharge loop; The time that discharges and recharges of detecting variable capacitor by processor is again according to the method for the measurement F value in the preceding text, draws written 8 force value that receive.Processor comprises the comparator sum counter, and wherein, comparator terminal links to each other with the RC charge-discharge circuit; The other end links to each other with reference voltage; When the voltage on the variable capacitor rose or drop to the reference voltage level size, comparator just generated and interrupts, and ends the counter timing.

In this structure of position indicating device of the present invention, can know that according toforce analysis nib 8 pressure equals the elastic force of spring, the introducing of spring makes it possible to measure the size of the power thatnib 8 receives.Hereinafter will explain how to record the power thatnib 8 receives.

The method of measured pressure value F mainly may further comprise the steps:

After stressed the pressing of nib, pressure acts on thepole plate 2, and spring stress generation deformation x equates with the displacement ofpole plate 2, obtains the displacement d ofpole plate 2 according toformula 1 andformula 2.

F=kx (formula 1)

D=x (formula 2)

Wherein, k is the coefficient of elasticity ofspring 10.

The displacement ofsecond pole plate 4 causes changing over against area S between pole plate, shown informula 3.

S=ld (formula 3)

Wherein, l is the width of intersection betweenfirst pole plate 3 andsecond pole plate 4, generally speaking; For convenience of calculation; The width offirst pole plate 3 andsecond pole plate 4 is set to equate, and coincidence fully on width, and l is the width offirst pole plate 3 orsecond pole plate 4 like this.

After changing over against area S between pole plate, just influence the size of capacitance C, shown informula 4.

$C=\frac{\mathrm{\&epsiv;<figure-callout\; label="S"\; filenames="HDA0000095878550000031.png,HDA0000095878550000032.png"\; state="\{\{state\}\}">S</figure-callout>}}{4\mathrm{\&pi;\; KD}}$(formula 4)

Wherein, electric capacity K is the electrostatic force constant, and ε is a dielectric constant, and D is the distance betweenfirst pole plate 3 andsecond pole plate 4.

After capacitance C size variation, will influence capacitor charge and discharge t, with the charging interval example, shown informula 5.

$t=\mathrm{RC}\mathrm{Ln}\frac{U}{U_E}$(formula 5)

Wherein, R is the circuit resistance, and U is a power source voltage in the charging and discharging road, U_EBe the reference voltage on the pin on the input of comparator, can set the size of reference voltage level through program.As stated, drop to voltage U when circuit discharging voltage_EThe time will produce interruption, thereby make counter stop counting, each gate time equates at interval, and then draws gate time t.

The capacitor charge and discharge time, t changed, and just influenced the times N of the counter of processor, shown informula 6.

$N=\frac{t}{\mathrm{\&Delta;\; t}}$(formula 6)

Wherein, Δ t is the time interval that counter is counted each time.

Getformula 7 according to formula 1-formula 6 simultaneous, just can obtain the pen point pressure size throughformula 7.

$F=\mathrm{<figure-callout\; label="N"\; filenames="HDA0000095878550000031.png,HDA0000095878550000032.png"\; state="\{\{state\}\}">N</figure-callout>}\frac{4\mathrm{\&pi;\; KkD\&Delta;\; t}}{\mathrm{R\&epsiv;}l\mathrm{Ln}\frac{U}{U_E}}={\mathrm{Nk}}^{\&prime;}$(formula 7)

$k^{\&prime;}=\frac{4\mathrm{\&pi;KkD\&Delta;t}}{\mathrm{R\&epsiv;}l\ln \frac{U}{U_E}}$

Therefore only can know that byformula 7 each parameter is constant in k ' formula, need can draw the power that receives according to the times N of the counter of processor.

Variable capacitor of the present invention and utilize the position indicating device of this variable capacitor; Adopt pressure to cause pole plate to slide; Thereby between pole plate relative position change between pole plate over against area, spring deformation be directly proportional over against area, thereby accurately obtain the size of pressure; In addition, adopt micromatic setting to regulate the position of pole plate, change between the pressure-less state bottom crown over against area, overcome the problem of " leaking " and " not water outlet ".

Need to prove that at last the above is merely preferred embodiments of the present invention, rather than to the qualification of technical scheme of the present invention, anyly be equal to replacement or corresponding improvement, still within protection scope of the present invention what technical characterictic of the present invention was done.

Claims (7)

1. a variable capacitor is characterized in that, comprising:

Capacitor casing (6);

Be arranged on the dielectric (5) in the housing (6), it has two relative sides;

First pole plate (3), it vertically is arranged on a side of dielectric (5);

Second pole plate (4), it vertically is arranged on the opposite side of dielectric (5), and touches with the flanked of dielectric (5);

Elastomeric element, it is connected with second pole plate (4);

Wherein, when second pole plate (4) when not being under pressure, between first pole plate (3) and second pole plate (4) is zero over against area, thereby the capacitance of variable capacitor is zero; When second pole plate (4) when being under pressure, it moves upward and elasticity of compression parts, with change between first pole plate (3) and second pole plate (4) over against area, thereby the capacitance of change variable capacitor.

2. variable capacitor as claimed in claim 1 is characterized in that, also comprises:

Be arranged on first insulation barrier (11) of second pole plate (4) top;

Second insulation barrier (12), the below that it is arranged on the bottom of capacitor casing (6) and is positioned at second pole plate (4), extraneous applied pressure acts on this second insulation barrier (12).

3. variable capacitor as claimed in claim 2 is characterized in that, elastomeric element is spring (10), and an end of this spring (10) is fixed on first insulation barrier (11), and the other end is fixed on the top inner surface of capacitor casing (6).

4. variable capacitor as claimed in claim 1 is characterized in that, also comprises micromatic setting (9), is used to adjust the position of first pole plate (3).

5. variable capacitor as claimed in claim 1 is characterized in that, when second pole plate (4) when not being under pressure, elastomeric element in the raw.

6. each the position indicating device of variable capacitor of use such as claim 1-4 is characterized in that, comprising:

The shell that is used to grip;

The variable capacitor that is used for gaging pressure, wherein, first pole plate (3) is drawn out to outside the capacitor casing (6) through first conducting rod (1), and second pole plate (4) is drawn out to outside the capacitor casing (6) through second conducting rod (2);

Processor, this processor links to each other with variable capacitor with second conducting rod (2) through first conducting rod (1), is used to measure discharging and recharging the time of variable capacitor.

7. position indicating device as claimed in claim 6 is characterized in that, also comprises the nib (8) that is arranged on outer casing end, and the one of which end is fixed on second insulation barrier (12) of variable capacitor, and the other end extends to the outside of shell.

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