CN101673163A - A sensing circuit used in a capacitance touching control panel - Google Patents

Abstract

The invention discloses a sensing circuit used in a capacitance touching control panel, which helps noise pass by adding a path, so as to reduce noise by differential treatment to the noise by going through two identical paths of same electrical doncitions, and the sensing signal can be correctly sensed.

Description

The sensing circuit that is used for capacitance type touch-control panel

Technical field

The invention discloses a kind of sensing circuit, particularly about a kind of sensing circuit that is used for capacitance type touch-control panel.

Background technology

The application of contact panel at present is very extensive, and the screen, Automatic Teller Machine of information inquiry etc. are provided as mobile phone, public arena, and its intuitive operation replaces keyboard and mouse function, and is quite convenient in the use.

Seeing also Fig. 1 and Fig. 2, is the synoptic diagram of two kinds of capacitance type touch-control panel 150,250 sensing touched positions.In Fig. 1, capacitance type touch-control panel 150 comprises the sense wire of directions X and Y direction, i.e. sense wire X ₁To sense wire X ₄And sense wire Y ₁To sense wire Y ₄, each sense wire has several sensing electrodes (not shown) respectively, and the sense capacitance value of each sensing electrode is with sense capacitance C _SenseExpression.When the touchless incident takes place, this sense capacitance C _SenseValue be zero, when having touch event to take place, this sense capacitance C _SenseValue then be not equal to zero.The capacitance type touch-control panel 150 of Fig. 1 is to come the touched position of sensing by the mode that order (Sequential) scans each sweep trace.As shown in Figure 1, scanning sequency is from sense wire Y ₁Be scanned up to sense wire Y ₄, and then from sense wire X ₁Be scanned up to sense wire X ₄For example, as sense wire X ₄And sense wire Y ₁Point of crossing when touched, by sense capacitance C _SenseThe variation of capacitance, and learn touched position.

Another kind of sensing mode only scans the sweep trace of single direction, and Sao Miao direction is not then imported excitation signal (Stimulating Signal), and as shown in Figure 2, capacitance type touch-control panel 250 comprises the sense wire of directions X and Y direction equally, i.e. sense wire X ₁To sense wire X ₄And sense wire Y ₁To sense wire Y ₄, scanning sequency is from sense wire X ₁Be scanned up to sense wire X ₄, and sense wire Y ₁To sense wire Y ₄Directly import excitation signal.Be sense wire Y ₁The input excitation signal scans sense wire X in regular turn ₁To sense wire X ₄, follow sense wire Y ₂The input excitation signal scans sense wire X more in regular turn ₁To sense wire X ₄, the rest may be inferred.Sense capacitance C _TransRepresentative be sense wire X ₁And sense wire Y ₁Between coupling capacitance, sense wire X ₁And sense wire Y ₁When the point of crossing is touched and not touched, sense capacitance C _TransHas different values.As Fig. 1, by checking sense capacitance C where _TransCapacitance change, thereby learn touched position.

See also Fig. 3, be the calcspar of sensing circuit 100 in the comprehensive above-mentioned schematic diagram prior art.Sensing circuit 100 comprises sensing cell 102 (sensing electrode), sensing signal generation unit 104 and integrator 106.Sensing cell 102 has the sense capacitance C of Fig. 1 _SenseOr the sense capacitance C of Fig. 2 _TransRepresented being used in reference to is shown with the capacitance that touchless takes place, when the capacitance type touch-control panel 250 of the capacitance type touch-control panel 150 of Fig. 1 or Fig. 2 is touched, the capacitance of sensing cell 102 changes, 104 of sensing signal generation units produce a sensing signal according to capacitance variation, this sensing signal is a voltage signal, input to integrator 106 and carry out integration, and integral result is exported to judge touched position.

Yet, no matter be the capacitance type touch-control panel 150 of Fig. 1 or the capacitance type touch-control panel 250 of Fig. 2, all exist the problem of noise effect sensing signal.Know as one of skill in the art, sensing cell 102 is to be made on the sensing electrode substrate (not shown), and sensing signal generation unit 104 and integrator 106 then are made on array (Array) substrate (not shown) of liquid crystal panel.Has a common voltage electrode (Common Electrode between the array base palte of sensing electrode substrate and liquid crystal panel; Not shown) in order to liquid crystal panel required voltage quasi position of when operation to be provided.When liquid crystal panel was operated, the energising altogether that the common voltage electrode is provided pressed signal unclean, that is contains noise, source bus line (SourceBus when for example driving liquid crystal panel; Not shown) the precharge (Pre-Charge) and the conducting of switch and disconnect action or the like and can produce noise, this noise can enter the sensing circuit 100 of Fig. 3, causes can't the sensing touched position of sensing circuit 100 or the problem of sensing mistake to take place easily.

Therefore need a kind of method to solve the problem of above-mentioned noise effect sensing signal.

Summary of the invention

For addressing the above problem, the object of the present invention is to provide a kind of sensing circuit that is used for capacitance type touch-control panel, it is the size of reducing noise significantly, makes the sensing signal can be by correct sensing.

For achieving the above object, the present invention adopts following technical scheme: a kind of sensing circuit that is used for capacitance type touch-control panel comprises a sensing signal portion, a reference signal portion and an integrator.Sensing signal portion is in order to based on the capacitance of capacitance type touch-control panel and a noise of reception, and to produce a sensing signal, the capacitance of this capacitance type touch-control panel is different under touched and not touched situation.Reference signal portion is in order to receiving this noise and to export a reference signal, and has the electric condition identical with sensing signal portion.Integrator is subtracted each other sensing signal and reference signal, and is produced an output signal in order to receive sensing signal and reference signal.

For achieving the above object, the present invention also adopts following technical scheme: a kind of sensing circuit that is used for capacitance type touch-control panel comprises a sensing signal path, a reference signal path and one first differential amplifier.The sensing signal path is in order to based on the capacitance of capacitance type touch-control panel and a noise of reception, and to produce a sensing signal, the capacitance of this capacitance type touch-control panel is different under touched and not touched situation.The reference signal path is in order to receiving this noise and to export a reference signal, and has the electric condition identical with the sensing signal path.First differential amplifier is subtracted each other sensing signal and reference signal, and is produced an output signal in order to receive sensing signal and reference signal.

Compared with prior art, the present invention passes through for noise by increasing by a path, make noise via identical two paths of electric condition by after subtracting each other again, significantly lower the size of noise in the sensing signal, make the output signal that only surplus sensing element produced and can be increased the sensitivity and the correctness of sensing circuit by correct sensing.

The present invention is described further below in conjunction with accompanying drawing and embodiment.

Description of drawings

Fig. 1 and Fig. 2 are the synoptic diagram of two kinds of capacitance type touch-control panel sensing touched positions.

Fig. 3 is the calcspar of sensing circuit in the schematic diagram prior art.

Fig. 4 is the calcspar according to sensing circuit of the present invention.

Fig. 5 is the circuit diagram according to first embodiment of Fig. 4.

Fig. 6 is the circuit diagram according to second embodiment of Fig. 4.

Fig. 7 is that an electronic installation comprises a capacitance type touch-control panel, and wherein capacitance type touch-control panel comprises according to sensing circuit of the present invention.

Embodiment

Relevant detailed description of the present invention and technology contents, existing as follows with regard to accompanying drawings.The explanation of following examples is with reference to additional diagram, is used for the specific embodiment that illustration the present invention can be used for implementing.

See also Fig. 4, be calcspar according to sensing circuit 400 of the present invention.Sensing circuit 400 can reduce the noise S that produces because of common voltage electrode 440 in the capacitance type touch-control panel (not shown) _Noise Influence.Sensing circuit 400 consists essentially of a sensing signal portion 411, a reference signal portion 421 and an integrator 406.Sensing signal portion 411 is in order to based on the capacitance of capacitance type touch-control panel and the noise S of reception _NoiseProduce a sensing signal S _tThe capacitance of capacitance type touch-control panel is different under touched and not touched situation.Reference signal portion 421 is in order to receive noise S _NoiseAnd export a reference signal S _Noise'.This reference signal portion 421 is analog sensing signal portions 411 and have the electric condition identical with sensing signal portion 411.Integrator 406 is in order to receive sensing signal S _tAnd reference signal S _Noise', its characteristic is that the difference with two input ends gives integration, so integrator 406 is with sensing signal S _tAnd reference signal S _Noise' subtracted each other, and produce an output signal S _Out

Reference signal portion 421 has a capacitance, and the capacitance when this capacitance is not touched with sensing signal portion 411 in fact equates.The identical electronic component of reference signal portion 421 and the equivalent electrical circuit that these electronic component connected modes are analog sensing signal portion 411 of being meant of sensing signal portion 411 and reference signal portion 421 electric conditions, so that electrical specifications such as both impedances, capacitance are consistent as far as possible, its purpose is to make noise S _NoiseBy identical circuit, guarantee noise S _NoiseThe value that enters integrator 406 by sensing signal portion 411 and reference signal portion 421 backs is identical as far as possible.

For making the present invention be easier to understand, below with comparative descriptions prior art and difference of the present invention.See also Fig. 5, be circuit diagram according to first embodiment of Fig. 4.This embodiment is used for scanning the sensing circuit 500 that scans the capacitance type touch-control panel of other direction after the direction again.Sensing signal portion 511 comprises a sensing cell 512 and a sensing signal generation unit 514.Reference signal portion 521 comprises a reference unit 522 and a reference signal generation unit 524.

Sensing cell 512 has a sense capacitance value, promptly with sense capacitance C _SenseThe expression capacitance.When capacitance type touch-control panel is not touched, the sense capacitance C of sensing cell 512 _SenseCapacitance be zero, when capacitance type touch-control panel is touched, sense capacitance C _SenseCapacitance non-vanishing.In addition, sensing cell 512 also has parasitic capacitance value, for the equivalent capacitance value between common voltage electrode 540 and the sensing electrode substrate, with stray capacitance C _Par1Expression.The noise S of common voltage electrode 540 _NoiseBe via stray capacitance C _Par1Be coupled to sensing cell 512.

Sensing cell 512 is via stray capacitance C _Par1Receive noise S _Noise, and have one first equivalent capacitance value or one second equivalent capacitance value.First equivalent capacitance value is capacitance (the sense capacitance C of capacitance type touch-control panel when touched _SenseCapacitance) and stray capacitance C _Par1The equivalent capacitance value of capacitance, second equivalent capacitance value is capacitance (the sense capacitance C of capacitance type touch-control panel when not touched _SenseCapacitance be zero) and stray capacitance C _Par1The equivalent capacitance value of capacitance.Sensing signal generation unit 514 is coupled to sensing cell 512, according to first equivalent capacitance value and noise S _Noise, or according to second equivalent capacitance value and noise S _NoiseProduce sensing signal S _t

The signal of the node 1 of Fig. 5 comprises control signal V _TogglePart and noise S that (as a square wave) produced _NoiseThe part that is produced.Control signal V _ToggleBe the signal that adds, be used for reaction and have or not the incident of touching (that is sense capacitance C _SenseValue) generation, i.e. control signal V _ToggleBe used for first equivalent capacitance value or second equivalent capacitance value are converted to the variation of signal, have or not the incident of touching with expression, wherein control signal V _ToggleSee through one first coupling capacitance C _C1Be coupled to sensing signal generation unit 514.As for noise S _NoiseSee through stray capacitance C _Par1Coupling and result from the part S of node 1 _1noiseCan try to achieve by following (1) formula:

$S_{1\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}1}}{C_{\mathrm{par}1}+C_{c1}+C_{\mathrm{sense}}}\right)---\left(1\right)$

Noise S _NoiseExcept sensing signal portion 511 was passed through in meeting, the present invention set up the noise S of another path for common voltage electrode 540 _NoiseBy.Reference unit 522 receives noise S _NoiseAnd have a C grade and imitate capacitance.It is capacitance and the stray capacitance C of artificial capacitor formula contact panel when not touched that C grade is imitated capacitance _Par1The equivalent capacitance value of capacitance, promptly have the numerical value identical with second equivalent capacitance value of sensing cell 512.Therefore reference unit 522 has a capacitor C _Par2, in order to the analog parasitic capacitor C _Par1Noise S _NoiseSee through capacitor C _Par2Be coupled to reference unit 522.As mentioned above, stray capacitance C _Par1Be the equivalent capacity between common voltage electrode 540 and the sensing electrode substrate, can get by measurement, and capacitor C _Par2Then be a capacitor that adds, have and stray capacitance C _Par1The capacitance of Xiang Denging in fact.

The circuit of reference signal generation unit 524 is identical with the circuit of sensing signal generation unit 514, and imitates capacitance and noise S according to the C grade of reference unit 522 _NoiseOutput reference signal S _Noise'.Reference signal generation unit 524 has second a coupling capacitance C who adds _C2, for the electric condition that makes reference signal portion 521 is identical with the electric condition of sensing signal portion 511, control signal V _ToggleAs seeing through the first coupling capacitance C _CiBe coupled to as the sensing signal generation unit 514, also see through the second coupling capacitance C _C2Be coupled to reference signal generation unit 524, so that noise S _NoiseElectric condition by reference signal portion 521 is identical with the electric condition that passes through sensing signal portion 511.The second coupling capacitance C wherein _C2The capacitance and the first coupling capacitance C _C1Capacitance equal in fact.So noise signal S of node 2 _2noiseFor:

$S_{2\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}2}}{C_{\mathrm{par}2}+C_{c2}}\right)$

Because capacitor C _Par2Capacitance and stray capacitance C _Par1Capacitance equal in fact, and the second coupling capacitance C _C2The capacitance and the first coupling capacitance C _C1Capacitance equal in fact, therefore:

$S_{2\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}1}}{C_{\mathrm{par}1}+C_{c1}}\right)$

The noise difference of 506 liang of input ends of input integral device is:

$S_{1\mathrm{noise}}-S_{2\mathrm{noise}}=S_{\mathrm{noise}}(\frac{C_{\mathrm{par}1}}{C_{\mathrm{par}1}+C_{c1}+C_{\mathrm{sense}}}-\frac{C_{\mathrm{par}1}}{C_{\mathrm{par}1}+C_{c1}})$

$=S_{\mathrm{noise}}\left[\frac{-C_{\mathrm{par}1}\×C_{\mathrm{sense}}}{(C_{\mathrm{par}1}+C_{c1}+C_{\mathrm{sense}})\×(C_{\mathrm{par}1}+C_{c1})}\right]---\left(2\right)$

The noise S that compares the prior art of (1) formula _1noiseNoise (S with first embodiment of (2) formula _1noise-S _2noise) can get, the size of the noise of (2) formula reduces than the size of the noise of (1) formula

Doubly, can get rid of noise S via the signal behind integrator 506 integrations _Noise, and the sensitivity of increase sensing circuit 500.

Sensing signal portion 511 can comprise that preferably one first wave filter 518 is coupled between sensing signal generation unit 514 and the integrator 506, in order to the sensing signal S of filtering via 514 generations of sensing signal generation unit _tHFS.According to sensing signal portion 511, reference signal portion 521 comprises that preferably one second wave filter 528 is coupled between reference signal generation unit 524 and the integrator 506, and the circuit of second wave filter 528 is identical with the circuit of first wave filter 518, in order to filtering reference signal S _Noise' HFS.

In the present embodiment, first wave filter 518 comprises one the 3rd resistance R ₃Be coupled between sensing signal generation unit 514 and the integrator 506; And one the 3rd capacitor C ₃Be coupled between an integrator 506 and the earth terminal.Second wave filter 528 comprises one the 4th resistance R ₄Be coupled between reference signal generation unit 524 and the integrator 506; And one the 4th capacitor C ₄Be coupled between an integrator 506 and the earth terminal.For the circuit that makes first wave filter 518 is identical with the circuit of second wave filter 528, the 3rd resistance R ₃Resistance value and the 4th resistance R ₄Resistance value equal in fact, the 3rd capacitor C ₃Capacitance and the 4th capacitor C ₄Capacitance equal in fact.

Integrator 506 comprises one first differential amplifier 532, one first resistance R ₁And one first capacitor C ₁First differential amplifier 532 has an inverting input (-), a non-inverting input (+) and an output node 4.First resistance R ₁Be coupled between sensing signal portion 511 and the inverting input (-).First capacitor C ₁Be coupled between inverting input (-) and the output node 4.For making noise S _NoiseThe path of being passed through before 532 two input ends of first differential amplifier is identical entering, and integrator 506 has more a ground connection matching unit 536 usefulness so that to import the circuit of non-inverting input (+) of first differential amplifier 532 identical with the circuit of inverting input (-) of input first differential amplifier 532.Ground connection matching unit 536 comprises one second resistance R ₂And one second capacitor C ₂, and second resistance R ₂Value must design and first resistance R ₁Value equate second capacitor C ₂Value must with first capacitor C ₁Value equate.Second resistance R ₂Be coupled between the non-inverting input (+) of the reference signal portion 521 and first differential amplifier 532 second capacitor C ₂Then be coupled between the non-inverting input (+) and an earth terminal of first differential amplifier 532.

Sensing signal portion 511 adds first resistance R in the integrator 506 ₁And first capacitor C ₁Constitute according to touchless and noise S are arranged _NoiseThe sensing signal S that is produced _tThe fullpath that is passed through can be considered sensing signal path 510.And second resistance R in reference signal portion 521 and the integrator 506 ₂, second capacitor C ₂Constitute noise S _NoiseThe path of passing through can be considered reference signal path 520.Reference signal path 520 is analog sensing signal paths 510, so that the electric condition in two paths is identical.

Output terminal at integrator 506 more can be coupled to an amplifying unit 530, in order to amplify the output signal S that integrator 506 is produced _OutAmplifying unit 530 comprises one second differential amplifier 534, the 5th resistance R ₅And the 6th resistance R ₆Second differential amplifier 534 has an inverting input (-), a non-inverting input (+) and an output node 3, and non-inverting input (+) is coupled to the output node 4 of integrator 506.The 5th resistance R ₅Be coupled between an inverting input (-) and the earth terminal.The 6th resistance R ₆Be coupled between inverting input (-) and the output node 3.

The switch SW of sensing signal generation unit 514 ₁In order to switch the different scanning line, each sweep trace comprises several sensing cells 512, and the remainder element comprises the part that integrator 506, first wave filter 518, reference unit 522, reference signal generation unit 524, ground connection matching unit 536, second wave filter 528 and amplifying unit 530 are shared for all sweep traces.

On the side circuit layout, sensing signal generation unit 514, first wave filter 518, reference signal portion 521, integrator 506 and amplifying unit 530 are integrated in the array base palte of liquid crystal panel usually, or being independent of array base palte makes.As mentioned above, each sensing cell 512 is the sensing electrode in the capacitance type touch-control panel, for being made on the sensing electrode substrate.

See also Fig. 6, be circuit diagram according to second embodiment of Fig. 4.This embodiment only scans a direction for being used for, the embodiment of sensing circuit 600 in the capacitance type touch-control panel of other direction input excitation signal.Sensing signal portion 611 comprises a sensing cell 612 and a sensing signal generation unit 614.Reference signal portion 621 comprises a reference unit 622 and a reference signal generation unit 624.

When capacitance type touch-control panel was touched, sensing cell 612 had a sense capacitance value, promptly with sense capacitance C _TransThe expression capacitance.Capacitance when capacitance type touch-control panel is not touched, the capacitor C when promptly reference unit 622 artificial capacitor formula contact panels are not touched _Trans' the expression capacitance.In addition, sensing cell 612 also has parasitic capacitance value, for the equivalent capacitance value between common voltage electrode 640 and the sensing electrode substrate, with stray capacitance C _Par3And stray capacitance C _Par5Expression.The noise S of common voltage electrode 640 _NoiseBe via stray capacitance C _Par3Be coupled to sensing cell 612.

Sensing cell 612 is via stray capacitance C _Par3Receive noise S _Noise, and have one first equivalent capacitance value or one second equivalent capacitance value.First equivalent capacitance value is capacitance (the sense capacitance C of capacitance type touch-control panel when touched _TransThe expression capacitance) and stray capacitance C _Par3, C _Par5The equivalent capacitance value of capacitance, second equivalent capacitance value is the capacitor C of capacitance type touch-control panel when not touched _Trans' expression capacitance and stray capacitance C _Par3, C _Par5The equivalent capacitance value of capacitance.Sensing signal generation unit 614 is coupled to sensing cell 612, according to first equivalent capacitance value and noise S _Noise, or according to second equivalent capacitance value and noise S _NoiseProduce sensing signal S _t

The signal of the node 5 of Fig. 6 comprises control signal V _TogglePart and noise S that (as a square wave) produced _NoiseThe part that is produced.Control signal V _ToggleBe the signal that adds, be used for reaction and have or not the incident of touching (that is sense capacitance C _TransValue) generation, i.e. control signal V _ToggleBe used for first equivalent capacitance value or second equivalent capacitance value are converted to the variation of signal, have or not the incident of touching with expression, wherein control signal V _ToggleDirectly be applied to sensing cell 612 and sensing signal generation unit 614.As for noise S _NoiseSee through stray capacitance C _Par3Coupling and result from the part S of node 5 _5noiseCan try to achieve by following (3) formula:

${\mathrm{<figure-callout\; id="5"\; label="S"\; filenames="A2009101348500022H1.png"\; state="\{\{state\}\}">S</figure-callout>}}_{5\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}3}}{C_{\mathrm{par}3}+C_{\mathrm{trans}}}\right)---\left(3\right)$

Noise S _NoiseExcept sensing signal portion 611 was passed through in meeting, the present invention set up the noise S of another path for common voltage electrode 640 _NoiseBy.Reference unit 622 receives noise S _NoiseAnd have a C grade and imitate capacitance.It is the capacitor C of artificial capacitor formula contact panel when not touched that C grade is imitated capacitance _Trans' expression capacitance and stray capacitance C _Par3, C _Par5The equivalent capacitance value of capacitance, promptly have the numerical value identical with second equivalent capacitance value of sensing cell 612.Therefore reference unit 622 has capacitor C _Par4And capacitor C _Par6Represent the analog parasitic capacitor C respectively _Par3, C _Par5Noise S _NoiseSee through capacitor C _Par4Be coupled to reference unit 622.Identical with first embodiment of Fig. 5, capacitor C _Par4And capacitor C _Par6Be the capacitor that adds, have respectively and stray capacitance C _Par3And capacitor C _Par5The capacitance of Xiang Denging in fact.

The circuit of reference signal generation unit 624 is identical with the circuit of sensing signal generation unit 614, and imitates capacitance and noise S according to the C grade of reference unit 622 _NoiseOutput reference signal S _Noise'.For the electric condition that makes reference signal portion 621 is identical with the electric condition of sensing signal portion 611, control signal V _ToggleAlso directly be applied to reference unit 622 and reference signal generation unit 624 as being applied to as sensing cell 612 and the sensing signal generation unit 614, so that noise S _NoiseElectric condition by reference signal portion 621 is identical with the electric condition that passes through sensing signal portion 611.So noise S of node 6 _6noiseFor:

$S_{6\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}4}}{C_{\mathrm{par}4}+C_{{\mathrm{trans}}^{\&prime;}}}\right)$

Because capacitor C _Par4Capacitance and stray capacitance C _Par3Capacitance equal in fact, therefore:

$S_{6\mathrm{noise}}=S_{\mathrm{noise}}\left(\frac{C_{\mathrm{par}3}}{C_{\mathrm{par}3}+C_{{\mathrm{trans}}^{\&prime;}}}\right)$

The noise difference of 606 liang of input ends of input integral device is:

${\mathrm{<figure-callout\; id="5"\; label="S"\; filenames="A2009101348500022H1.png"\; state="\{\{state\}\}">S</figure-callout>}}_{5\mathrm{noise}}-S_{6\mathrm{noise}}=S_{\mathrm{noise}}(\frac{C_{\mathrm{par}3}}{C_{\mathrm{par}3}+C_{\mathrm{trans}}}-\frac{C_{\mathrm{par}3}}{C_{\mathrm{par}3}+C_{{\mathrm{tarns}}^{\&prime;}}})$

$=S_{\mathrm{noise}}\left[\frac{C_{\mathrm{par}3}\&times;C_{{\mathrm{trans}}^{\&prime;}}-C_{\mathrm{par}3}\&times;C_{\mathrm{trans}}}{(C_{\mathrm{par}3}+C_{\mathrm{trans}})\&times;(C_{\mathrm{par}3}+C_{{\mathrm{trans}}^{\&prime;}})}\right]---\left(4\right)$

The noise S that compares the prior art of (3) formula _5noiseNoise (S with second embodiment of (4) formula _5noise-S _6noise) can get, the size of the noise of (4) formula reduces than the size of the noise of (3) formula

Doubly, can get rid of noise S via the signal behind integrator 606 integrations _Noise, and the sensitivity of increase sensing circuit 600.

In the embodiment of circuit, the side circuit of first wave filter 618, second wave filter 628, integrator 606, ground connection matching unit 636 and amplifying unit 630 is as described in first embodiment of above-mentioned Fig. 5, so repeat no more.

As Fig. 5, sensing signal portion 611 adds the 7th resistance R in the integrator 606 ₇And the 7th capacitor C ₇Constitute according to touchless and noise S are arranged _NoiseThe sensing signal S that is produced _tThe fullpath that is passed through can be considered sensing signal path 610.And the 8th resistance R in reference signal portion 621 and the integrator 606 ₈, the 8th capacitor C ₈Constitute noise S _NoiseThe path of passing through can be considered reference signal path 620.620 analog sensing signal paths 610, reference signal path are so that the electric condition in two paths is identical.

Compared with prior art, the present invention passes through for noise by increasing the reference signal path, make noise via the identical sensing signal path of electric condition and reference signal path by after export two input ends of differential amplifier to, see through after differential amplifier subtracts each other the noise of two paths, significantly lower the size of noise in the sensing signal, make the output signal that only surplus sensing element produced of differential amplifier and can be increased the sensitivity and the correctness of sensing circuit by correct sensing.

Fig. 7 is that an electronic installation 700 comprises a capacitance type touch-control panel 750, and wherein capacitance type touch-control panel 750 comprises one of them according to sensing circuit 400,500 of the present invention and 600.Comprise as Fig. 4 to one of them capacitance type touch-control panel 750 of sensing circuit 400,500 shown in Figure 6 and 600 can be the part of electronic installation 700.Electronic installation 700 comprises a capacitance type touch-control panel 750 and a power supply unit 740, and power supply unit 740 couples to supply power to capacitance type touch-control panel 750 with capacitance type touch-control panel 750.Electronic installation 700 can be display on mobile phone, digital camera, personal digital assistant, mobile computer, desktop PC, TV, satellite navigation, the car, aviation with display or portable digital video disk (Digital Video Disc, DVD) projector etc.

Though the present invention discloses as above with embodiment; right its is not in order to qualification the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when can doing various changes and retouching, so protection scope of the present invention is as the criterion when looking appended the claim person of defining.

Claims (13)

1, a kind of sensing circuit that is used for capacitance type touch-control panel, it is characterized in that: comprising: a sensing signal portion, a reference signal portion and an integrator, wherein this sensing signal portion is in order to based on the capacitance of this capacitance type touch-control panel and a noise of reception, to produce a sensing signal, the capacitance of this capacitance type touch-control panel is different under touched and not touched situation; This reference signal portion is in order to receive this noise and to export a reference signal, and this reference signal portion has the electric condition identical with this sensing signal portion; Integrator is subtracted each other this sensing signal and this reference signal in order to receive this sensing signal and this reference signal, and produces an output signal.

2, sensing circuit as claimed in claim 1 is characterized in that: this reference signal portion has a capacitance, and the capacitance when this capacitance is not touched with this sensing signal portion in fact equates.

3, sensing circuit as claimed in claim 1 is characterized in that: this reference signal portion has several electronic packages, and these electronic components are for connecting to simulate the equivalent electrical circuit of this sensing signal portion.

4, sensing circuit as claimed in claim 1, it is characterized in that: this integrator comprises: one first differential amplifier, one first resistance and one first electric capacity, and wherein this first differential amplifier has an inverting input, a non-inverting input and an output node; This first resistance has one first end and is coupled to this sensing signal portion, and one second end is coupled to this inverting input; This first electric capacity has one first end and is coupled to this inverting input, and one second end is coupled to this output node.

5, sensing circuit as claimed in claim 4, it is characterized in that: this integrator more comprises a ground connection matching unit, this ground connection matching unit comprises: one second resistance and one second electric capacity, wherein this second resistance has one first end and is coupled to this reference signal portion, and one second end is coupled to this non-inverting input; This second electric capacity has one first end and is coupled to this non-inverting input, and one second end be coupled to an earth terminal, wherein the resistance value of this second resistance equates with the resistance value of this first resistance in fact, and the capacitance of this second electric capacity equates with the capacitance of this first electric capacity in fact.

6, sensing circuit as claimed in claim 1, it is characterized in that: this sensing signal portion comprises: a sensing cell and a sensing signal generation unit, wherein this sensing cell receives this noise via a stray capacitance, this sensing cell has one first equivalent capacitance value or one second equivalent capacitance value, this first equivalent capacitance value is the capacitance of this capacitance type touch-control panel when touched and the equivalent capacitance value of the capacitance of this stray capacitance, and this second equivalent capacitance value is the capacitance of this capacitance type touch-control panel when not touched and the equivalent capacitance value of the capacitance of this stray capacitance; This sensing signal generation unit is coupled to this sensing cell, according to this first equivalent capacitance value and this noise, or produces this sensing signal according to this second equivalent capacitance value and this noise; And

This reference signal portion comprises: a reference unit and a reference signal generation unit, this reference unit receives this noise and has a C grade imitates capacitance, and this C grade is imitated capacitance and is the capacitance of this capacitance type touch-control panel of simulation when not touched and the equivalent capacitance value of the capacitance of this stray capacitance; This reference signal generation unit is coupled to this reference unit, export this reference signal according to this C grade effect capacitance and this noise, wherein this reference unit has the circuit identical with this sensing cell, and this reference signal generation unit has the circuit identical with the sensing signal generation unit.

7, sensing circuit as claimed in claim 6, it is characterized in that: this sensing signal portion comprises that more one first wave filter is coupled between this sensing signal generation unit and this integrator, the HFS of this sensing signal that is produced via this sensing signal generation unit in order to filtering; This reference signal portion comprises that more one second wave filter is coupled between this reference signal generation unit and this integrator, and the circuit of this second wave filter is identical with the circuit of this first wave filter, in order to the HFS of this reference signal of filtering.

8, sensing circuit as claimed in claim 6 is characterized in that: comprising: one first coupling capacitance and one second coupling capacitance, and a control signal is coupled to this sensing signal generation unit via this first coupling capacitance; This control signal is coupled to this reference signal generation unit via this second coupling capacitance, and wherein the capacitance of this first coupling capacitance equates with the capacitance of this second coupling capacitance in fact.

9, sensing circuit as claimed in claim 6 is characterized in that: this reference unit comprises an electric capacity, and the capacitance of this electric capacity equates with the capacitance of this stray capacitance in fact, and this noise is capacitively coupled to this reference unit through this.

10, a kind of sensing circuit that is used for capacitance type touch-control panel, it is characterized in that: comprising: a sensing signal path, a reference signal path and one first differential amplifier, wherein this sensing signal path is in order to based on the capacitance of this capacitance type touch-control panel and a noise of reception, to produce a sensing signal, the capacitance of this capacitance type touch-control panel is different under touched and not touched situation; This reference signal path is in order to receive this noise and to export a reference signal, and this reference signal path has the electric condition identical with this sensing signal path; This first differential amplifier is subtracted each other this sensing signal and this reference signal in order to receive this sensing signal and this reference signal, and produces an output signal.

11, sensing circuit as claimed in claim 10 is characterized in that: this reference signal path has a capacitance, and the capacitance when this capacitance is not touched with this sensing signal path in fact equates.

12, sensing circuit as claimed in claim 10 is characterized in that: this reference signal path has several electronic packages, and these electronic components are for connecting to simulate the equivalent electrical circuit in this sensing signal path.

13, a kind of electronic installation is characterized in that: comprising:

One capacitance touching control road deck, comprise that as claim 1 or 10 described sensing circuits wherein this electronic installation is display on a mobile phone, a digital camera, a personal digital assistant, a mobile computer, a desktop PC, a TV, a satellite navigation, the car, an aviation with a display or a portable digital video disk projector.

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