TW201011620A - Sensing circuit for capacitive touch panel - Google Patents

Abstract

A sensing circuit for a capacitive touch panel is disclosed. By adding a path for a noise to be passed, the noise is differentially processed through two paths which have the same electrical conditions with each other. The noise is decreased significantly, and a sensing signal can be sensed correctly.

Description

201011620, s. 6. Description of the Invention: [Technical Field] The present invention relates to a sensing circuit', particularly a sensing circuit for a capacitive touch panel. [Prior Art] At present, touch panels are widely used, such as mobile phones, screens for providing information inquiry in public places, automatic teller machines, etc. The intuitive operation replaces the functions of the keyboard and the mouse, and is quite convenient to use. Referring to Figures 1 and 2, there are shown schematic diagrams of two capacitive touch panels 150, 250 sensing the touched position. In FIG. 1 , the capacitive touch panel 150 includes sensing lines in the X direction and the Y direction, that is, the sensing lines χ to the sensing lines X4 and the sensing lines 至 1 to □ 4 ′ each of the sensing lines respectively have a plurality of sensing lines. The sensing capacitance values of the electrodes (not shown)' respective sensing electrodes are represented by the sensing capacitance csense. When the no-touch event occurs, the value of the sensing capacitor Csense is zero. When a touch event occurs, the value of the sensing capacitor Csense is not equal to zero. m The capacitive touch panel 150 of Fig. 1 senses the touched position by scanning each of the scan lines into a sequence (SeqUentja丨). As shown in Fig. 2, the scanning order is scanned from the sensing line 丫1 to the sensing line 丫4, and then scanned from the sensing line center to the sensing line X4. For example, when the intersection of the sensing line X4 and the sensing line 丫1 is touched, the touched position is known by sensing the change in the capacitance value of the capacitor csense. Another sensing method scans only the scanning lines in a single direction, and the unscanning direction turns into a stimulating signal. As shown in FIG. 2, the capacitive touch panel 250 also includes sensing lines in the X direction and the γ direction. That is, the sensing line X1 to the sensing line X4 and the sensing line 丫1 to the sensing line 丫4, the scanning order is scanned from the sensing line X1 to the sensing line X4' and the sensing line A to the sensing line 丫4 are directly input to the excitation signal 3 201011620 '. That is, the sensing line 丫1 inputs the excitation signal, sequentially scans the sensing line X1 to the sensing line parent 4', then the sensing line 丫2 inputs the excitation signal, and then sequentially scans the sensing line father to the sensing line X4' and so on. Ctrans represents the sensing line X, and the coupling capacitance value between the sensing line '1. The sensing line C1 has a different value when the sensing line X1 and the sensing line 丫1 are touched and untouched. . As shown in the figure, the position of the touched position is known by checking where the capacitance of the sensing capacitor Ct rans changes. Referring to Fig. 3, the square circle of the sensing circuit ^ 100 in the conventional technique is integrated. The sensing circuit 1A includes a sensing unit 102 (sensing electrode), a sensing signal generating unit 104, and an integrator 106. The sensing unit 1〇2 has the sensing capacitance Csense of FIG. 1 or the sensing capacitance Ctrans of FIG. 2 for indicating the presence or absence of a capacitance value, when the capacitive touch panel 150 of FIG. 1 or When the capacitive touch panel 250 of FIG. 2 is touched, the capacitance value of the sensing unit 1 〇 2 is changed, and the sensing signal generating unit 1 〇 4 generates a sensing signal according to the change of the capacitance value. The voltage signal is input to the integrator 1〇6 to perform the integral' and the integral result is output to determine the position to be touched. ❹ However, the capacitive touch panel 彳5〇 of Figure 1 or the capacitive touch panel 250' of Figure 2 has the problem of noise affecting the sensing signal. As is well known in the art, the sensing unit 102 is fabricated on a sensing electrode substrate (not shown), and the sensing signal generating unit 1 〇 4 and the integrator 彳〇 6 are fabricated in an array of liquid crystal panels ( Array) on the substrate (not shown). A common voltage electrode (not shown) is provided between the sensing electrode substrate and the array substrate of the liquid crystal panel to provide a voltage level required for operation of the liquid crystal panel. When the liquid crystal panel is operated, the common voltage signal provided by the common voltage electrode is not clean, that is, it contains noise. For example, the pre-charging of the source busbar (not shown) when driving the liquid crystal panel (Pre- Charge) and the on and off actions of the switch will generate noise in 201011620. This noise will enter the sensing circuit 100 of FIG. 3 'Easy to cause the sensing circuit 100 to not sense the touched position or the sensing error. The problem has happened. Therefore, a method is needed to solve the above problem that the noise affects the sensing signal. SUMMARY OF THE INVENTION It is an object of the present invention to provide a sensing circuit for a capacitive touch panel by adding a path for noise to pass through, so that the noise is differentially processed through two paths having the same electrical condition. It can greatly reduce the size of the noise, so that the sensing ^5 signal can be correctly sensed. A sensing circuit for a capacitive touch panel according to the present invention includes a sensing signal portion, a reference signal portion, and an integrator. The sensing signal portion is configured to generate a sensing signal based on the capacitance value of the capacitive touch panel and receive a noise, and the capacitance value of the capacitive touch panel is touched and untouched. different. The reference signal portion is configured to receive the noise and output a reference signal, and has the same electrical condition as the sensing signal portion. The integrator is configured to receive the sensing signal and the reference signal to subtract the sensing signal and the reference signal, and generate a Φ-output signal. A sensing circuit for a capacitive touch panel according to the present invention includes a sensing signal path, a reference signal path, and a first differential amplifier. The sensing signal path is used to generate a sensing signal based on the capacitance value of the capacitive touch panel and receiving one of the noises, and the capacitance value of the capacitive touch panel is touched and untouched. different. The reference signal path is for receiving the noise and outputting a reference signal and having the same electrical condition as the sensing signal path. The first differential amplifier is configured to receive the sensing signal and the reference signal, subtract the sensing signal and the reference signal, and generate an output signal. 201011620 [Embodiment] Hereinafter, the technical content of the present invention will be described in detail with reference to the accompanying drawings. Referring to Figure 4, there is shown a block diagram of a sensing circuit 4A in accordance with the present invention. The sensing circuit 400 can reduce the noise Snoise effect generated by the common voltage electrode 440 in the capacitive touch panel (not shown). The sensing circuit 400 basically includes a sensing signal portion 411', a reference signal portion 421, and an integrator 406. The sensing signal portion 411 is configured to generate a sensing signal St based on the capacitance value of the capacitive touch panel and the received noise Snsise. The capacitance value of the capacitive touch panel is different when it is touched and not touched. The reference signal unit 421 is configured to receive noise

Snoise also outputs a reference signal sn0ise. The reference signal portion 421 is an analog sensing signal portion 411 and has the same electrical conditions as the sensing signal portion 411. The integrator 406 is configured to receive the sensing signal St and the reference signal Snoise, and the characteristic is to integrate the difference between the two inputs, so the integrator 406 subtracts the sensing signal st and the reference signal Snoise', and generates a Output signal sout. The reference signal portion 421 has a capacitance value which is substantially equal to the capacitance value when the sensing signal portion 411 is not touched. The same electrical conditions of the sensing signal portion 411 and the reference signal portion 421 refer to the electronic components of the reference signal portion 421 and the equivalent circuit of the analog component of the analog sensing signal portion 411 to make the impedance of the two, The electrical characteristics such as the capacitance value are as uniform as possible, and the purpose is to make the noise Snoise pass through the same circuit, and ensure that the noise snoise passes through the sensing signal portion 411 and the reference signal portion 421 and enters the value of the integrator 406 as much as possible. The invention will be more readily understood, and the differences between the prior art and the present invention will be described below. Referring to Fig. 5, there is shown a circuit diagram of a first embodiment according to Fig. 4. This embodiment is a sensing circuit 500 in a capacitive touch panel for scanning one direction and then scanning another direction. The sensing signal unit 511 includes a sensing unit 6 201011620 • a unit 512 and a sensing signal generating unit 514. The reference signal unit 521 includes a reference unit 522 and a reference signal generating unit 524. The sensing unit 512 has a sensing capacitance value, that is, the capacitance value is represented by the sensing capacitance Csense. When the capacitive touch panel is not touched, the capacitance of the sensing capacitor Csense of the sensing unit 512 is zero. When the capacitive touch panel is touched, the capacitance of the sensing capacitor Csense is not zero. Further, the sensing unit 512 also has a parasitic capacitance Cpar1 having a parasitic capacitance value 'as the equivalent voltage value between the common voltage electrode 54A and the sensing electrode substrate'. The noise snoise Φ of the common voltage electrode 54 is coupled to the sensing unit 5彳2 via the parasitic capacitance Cpar1_. The sensing unit 512 receives the noise Snsise via the parasitic capacitance CpaM and has a first equivalent capacitance value or a second equivalent capacitance value. The first equivalent capacitance value is a capacitance value when the capacitive touch panel is touched (ie, a capacitance value of the sensing capacitor Csense) and an equivalent capacitance value of a capacitance value of the parasitic capacitance CpaM, and the second equivalent capacitance value is a capacitance The capacitance value of the touch panel when it is not touched (that is, the capacitance value of the sensing capacitor is zero) and the equivalent capacitance value of the capacitance value of the parasitic capacitance CpaM. The sensing signal generating unit 514 is coupled to the sensing unit 512 according to the first equivalent capacitance value ❹ and the noise sn()ise or according to the second equivalent capacitance value and the noise Sn. (6) A sense signal St is generated. In the section of Figure 5, the signal at point 1 includes the control signal Vt. (4) The part produced by (such as a party wave) and the part produced by the noise Snoise. Control signal V Ding. _ is the additional signal 'when the reaction has no touch event (that is, the value of the sense capacitor C -), that is, the control signal VToggle is used to convert the first equivalent capacitance value or the second equivalent capacitance value into a signal The change is to indicate whether there is a touch event, wherein the control signal vToggle is coupled to the sensing signal generating unit 514 through a first reciprocal capacitor Cci. As for the noise snoise, the part S·! n〇jse generated by the CpaM coupling of the electricity generation valley is generated by the following formula (1): 7 201011620 f c ^

Sinoise = Sn〇ise -ΕΞ]_ /^ n

The Cparl + Ccl + Cs_ J noise 3n〇iSe, in addition to passing through the sensing signal portion 511, establishes another path for the noise Sn0ise of the common voltage electrode 540 to pass. The reference unit 522 receives the noise Snoise and has a third equivalent capacitance value. The third equivalent capacitance value is an equivalent capacitance value of the capacitance value of the analog capacitive touch panel when not touched and the capacitance value of the parasitic capacitance CpaM, that is, having the same value as the second equivalent capacitance value of the sensing unit 512. Value. Therefore, the reference unit 522 has a capacitor Cpw for modulating the pseudo parasitic capacitance. The noise Snoise is coupled to the reference unit 522 through the capacitor Cpar2. As described above, the parasitic capacitance cpaM is an equivalent capacitance between the common voltage electrode mo and the sensing electrode substrate, which can be obtained by measurement, and (4) Cpw is an external capacitor. 'There is a capacitance value substantially equal to the state of the parasitic capacitance Cp. The circuit of the reference signal generating unit 524 is identical to the circuit of the sensing signal generating unit 514' and outputs a reference signal snoise' according to the third equivalent capacitance value of the reference unit 522 and the noise sn〇ise. The reference signal generating unit 524 has an additional _th capacitor Ce2' for making the electrical condition of the reference signal portion 521 the same as the electrical condition of the sensible signal portion 511, and the control signal ντ. (4) The e-face is coupled to the sensing signal generating unit 514 through the first-side power transmission, and is also coupled to the reference signal generating unit 524 through the second combining capacitor U to pass the noise s_e through the reference signal. The electrical conditions of P 521 are the same as those of the sensing signal section. The capacitance value of the second coupling capacitor Cc2 is substantially equal to the capacitance value of the first coupling capacitor. Therefore, the node 2, the noise signal S2noise horse · (c λ ^2noise = Sn〇ise - , Cpar2 + Cc2 > since the capacitance value of the capacitor cpar2 is substantially equal to the capacitance value of the parasitic capacitance' and the capacitance of the second coupling capacitor Cc2 The value is substantially equal to the capacitance of the first coupling capacitor Cc1 8 201011620, therefore: wide c S2noise = Sn0ise pari VCparl + Ccl; the noise difference between the two inputs of the input integrator 506 is:

S 1 noise , S2noise*"Sn〇ise :s noise c pari

C pari cparl +Ccl +cse,

Cparl + Col ^parl X ^sense (2) (Cparl + Ccl + Csense)X (Cp^ + Ccl)· Compare the noise of the conventional technique of (1) with Sin〇ise and (2) In the noise of an embodiment (Sinoise_S2nojse), the size of the noise of the equation (2) is smaller than the size of the noise of the equation (1) by C·(Cparl+Ccl) times, and is integrated by the integrator 506. The signal can eliminate the noise Snoise, and the sensitive sensing signal portion 511 of the sensing circuit 500 can preferably include a first filter 518 coupled between the sensing signal generating unit 514 and the integrator 506 for filtering. Except for the high frequency portion of the sensing signal St generated by the sensing signal generating unit 514. The reference signal portion 511 ′ of the reference signal portion 521 preferably includes a second filter 528 coupled between the reference signal generating unit 524 and the integrator 506 , and the circuit of the second filter 528 and the first filter 518 . The circuit is the same to filter out the frequency portion of the reference signal Snoise. In this embodiment, the first filter 518 includes a third resistor R3 coupled between the sensing signal generating unit 514 and the integrator 506; and a third capacitor 〇3 coupled to the integrator 506 and a ground. Between the ends. The second filter 528 includes a fourth resistor R4 coupled between the reference signal generating unit 524 and the integrator 506; and a fourth capacitor 〇4 coupled between the integrator 506 and a ground. In order to make the circuit of the first filter 518 the same as the circuit 201011620 of the second filter 528, the resistance value of the third resistor R3 is substantially equal to the resistance value of the fourth resistor r4, and the capacitance value of the third capacitor C3 is the same as the fourth capacitor. The capacitance values of c4 are substantially equal. The integrator 506 includes a first differential amplifier 532, a first resistor, and a first capacitor 〇1. The first differential amplifier 532 has an inverting input (-), a non-inverting input (+), and an output node 4. The first resistor h is coupled between the sensing signal portion 511 and the inverting input terminal (1). The first capacitor C1 is coupled between the inverting input terminal (-) and the output node 4. In order for the noise Snoise to pass the same path before entering the two input terminals of the first differential amplifier 532, the integrator 506 further has a ground matching unit 536 for non-inverting the input first differential amplifier 532. The circuit of the input terminal (+) is the same as the circuit of the inverting input terminal (-) of the first differential amplifier 532. The ground matching unit 536 includes a second resistor R2 and a second capacitor 〇2, and the value of the second resistor R2 must be designed to be equal to the value of the first resistor R! 'The value of the second capacitor C2 must be the same as the first capacitor C· The values are equal. The second resistor R2 is coupled between the reference signal portion 521 and the non-inverting input terminal (+) of the first differential amplifier 532, and the second capacitor C2 is coupled to the non-inverting input terminal of the first differential amplifier 532. (+) and between a ground. The φ sensing signal portion 511 plus the first resistor h and the first capacitor 〇1 in the integrator 506 constitute a complete path through which the sensing signal St generated by the presence or absence of the touch and the noise Snoise passes, and can be regarded as a sensing signal. Path 510. The reference signal path 520 is formed by the reference signal portion 521 and the second resistor R2 and the second capacitor C2 of the integrator 506 forming a path through which the noise Sn <) is passed. The reference signal path 520 is an analog sense signal path 510 such that the electrical conditions of the two paths are the same. The output of the integrator 506 is further coupled to an amplifying unit 530 for amplifying the output signal Sout generated by the integrator 506. The amplifying unit 530 includes a second differential amplifier 534, a fifth resistor R5, and a sixth resistor R6. The second differential amplifier 534 has an inverting input (-), a non-inverting input (+), and a 201011620 output node 3' non-inverting input (+) coupled to the integrator 5〇6 wheel Exit node 4. The fifth resistor Rs is coupled between the inverting input terminal (1) and a ground terminal. The sixth resistor Re is consumed between the inverting input terminal (1) and the output node 3. The switch SW1 of the sensing signal generating unit 514 is used to switch different scan lines, each scan line includes a plurality of sensing units 512, and the remaining components include an integrator 506, a first filter 518, a reference unit 522, and a reference signal generation. The unit 524, the ground matching unit 536, the second filter 528, and the amplifying unit 53A are portions shared by all the scanning lines. In the actual circuit layout, the sensing signal generating unit 514, the first filter 518' reference signal portion 521, the integrator 5〇6, and the amplifying unit 53 are generally integrated on the array substrate of the liquid crystal panel, or are independent of the array substrate. production. As described above, each of the sensing units 512 is a sensing electrode in the capacitive touch panel and is formed on the sensing electrode substrate. Referring to Fig. 6, there is shown a circuit diagram of a second embodiment according to Fig. 4. This embodiment is an embodiment of the sensing circuit 600 in a capacitive touch panel for scanning only one direction and inputting an excitation signal in the other direction. The sensing signal unit 61 includes a sensing unit 612 and a sensing signal generating unit 614. The reference signal portion 621 includes a reference unit 622 and a reference signal generating unit 624. When the capacitive touch panel is touched, the sensing unit 612 has a sensing capacitance value, that is, a capacitance value represented by the sensing capacitance Ctrans. The capacitance value when the capacitive touch panel is not touched, that is, the reference capacitor 622 simulates the capacitance value of the capacitor Ctrans' when the capacitive touch panel is not touched, and further, the sensing unit 6彳2 has parasitic The capacitance value is an equivalent electric valley between the common voltage electrode 640 and the sensing electrode substrate, and the parasitic capacitance Cpar3 and the parasitic capacitance cpar5 indicate that the noise of the β common voltage electrode 640 is coupled to the sensing unit via the parasitic capacitance cpar3. 612. 11 201011620 The sensing unit 612 receives the noise snoise via the parasitic capacitance cpar3 and has a first equivalent capacitance value or a second equivalent capacitance value. The first equivalent capacitance value is a capacitance value when the capacitive touch panel is touched (the capacitance value of the sensing capacitance Ctrans is represented) and an equivalent capacitance value of the capacitance value of the parasitic capacitances cpar3 and cpar5, and the second equivalent capacitance value The capacitance Ctrans when the capacitive touch panel is not touched indicates the capacitance value and the equivalent capacitance value of the capacitance value of the parasitic capacitance cpai>3 and cpar5. The sensing signal generating unit 614 is coupled to the sensing unit 612, and generates a sensing signal ST according to the first equivalent capacitance value and the noise snoise, or according to the second equivalent capacitance value and the noise Snoise. The signal of node 5 in Fig. 6 includes the part generated by the control signal vT〇gg|e (such as a square wave) and the part generated by the noise Snoise. The control signal vToggle is an additional signal used to reflect the occurrence of a touch event (ie, the value of the sense capacitor Ctrans). That is, the control signal VT〇gg|e is used to set the first equivalent capacitance value or the second equivalent. The capacitance value is converted into a change of the signal to indicate whether there is a touch event, wherein the control signal VToggle is directly applied to the sensing unit 61 2 and the sensing signal generating unit 614. As for the noise Snmise generated by the parasitic capacitance cpar3, the Ssnoise generated by the node § parameter can be obtained by the following formula (3): i Q ^ S5noise = Sn〇ise ― ^ (3) \ par3 trans j noise Sn 〇 In addition to passing the sensing signal portion 611, the present invention establishes another path for the noise Snoise of the common voltage electrode 640 to pass. The reference unit 622 receives the noise Sn 〇ise and has a third equivalent capacitance value. The third equivalent capacitance value is the capacitance Ctrans when the analog capacitive touch panel is not touched, and the capacitance value and the equivalent capacitance value of the capacitance value of the parasitic capacitance Cpa “3, Cpar5”, that is, the sensing unit 612 The second equivalent capacitance value is the same value. Therefore, the reference unit 622 has a capacitance Cpar4 and a capacitance Cpar·6 respectively represents the analog parasitic capacitance cpar3, 12

❹ 201011620

The heart of the Cpar5 〇 日 耦合 is coupled to the reference cell 622 via the capacitor cpar4. The capacitor Cpar4 and the capacitor Cpar6 are respectively applied with capacitors 'which are substantially equal to the parasitic capacitance Cpar3 and the capacitance Cpar5, respectively. Capacitance value. The circuit of the reference signal generating unit 624 is identical to the circuit of the sensing signal generating unit 614' and outputs a reference signal Snoise' according to the third equivalent capacitance value of the reference unit 622 and the noise Snoise. In order to make the electrical condition of the reference signal portion 621 and the electrical condition of the sensing signal portion 611 the same, the control signal vToggle is directly applied to the reference unit 622 and the reference signal generating unit as applied to the sensing unit 612 and the sensing signal generating unit 614. 624, so that the electrical condition of the noise Snoise passing the reference signal portion 621 is the same as the electrical condition passing through the sensing signal portion 611. Therefore, the noise S6noise of node 6 is: (Q \ S6noise = Snoise -^ V par4 ^trans' j Since the capacitance value of the capacitance cpa "4 is substantially equal to the capacitance value of the parasitic capacitance cpar3, therefore: (Q, S^noise —Sn〇ise ————— Γ j-Γ V ^trans' j The noise difference between the two inputs of the input integrator 606 is: S5nolse_S6noise_Sn〇ise

:S noise

C par3 c +Ct c (four) xC, par3

Cpar3 + Ct (Cpar3 + (4) compares the noise Ssn〇ise of the conventional technique of the formula (3) with the noise of the second embodiment of the formula (4) (S5noise-S6noise), the fourth (4) The size of the noise is smaller than the size of the 13th 201011620 type noise C-C ^trans*_trans (Cpar3 + CtnmS') times, and the signal integrated by the integrator 606 can eliminate the noise Snoise, and the sense of increase Sensitivity of the measuring circuit 600 In the embodiment of the circuit, the first circuit 618, the second wave 628, the integrator 606, the ground matching unit 636, and the actual circuit of the amplifying unit 630 are as in the first embodiment of FIG. 5 described above. As described in FIG. 5, the sensing signal portion 611 is added with the seventh resistor R in the integrator 606, and the seventh capacitor 〇7 is formed according to the presence or absence of the touch and the noise sn()iSe. The complete path through which the raw sensing signal passes can be regarded as the sensing signal path 610. The reference signal portion 621 and the eighth resistor R8 and the eighth capacitor Ce in the integrator 606 form a path through which the noise SnQise passes, which can be regarded as Reference signal path 620. Reference signal path 620 is analog sensing signal path 61 〇 Therefore, the electrical conditions of the two paths are the same. The invention increases the reference signal path for the noise to pass, so that the noise passes through the sensing signal path and the reference signal path with the same electrical condition and is output to the two input ends of the differential amplifier. After the noise of the two paths is reduced by the differential amplifier, the size of the noise in the sensing signal is greatly reduced, so that the output of the differential amplifier can only be correctly sensed by the signal generated by the sensing component. The sensitivity and accuracy of the sensing circuit are increased. FIG. 7 illustrates an electronic device 7A including a capacitive touch panel 750, wherein the capacitive touch panel 75A includes the sensing circuit 400 according to the present invention, The capacitive touch panel 75A including one of the sensing circuits 400, 500, and 600 as shown in FIGS. 4 to 6 may be part of the electronic device 700. The electronic device 700 includes a capacitive touch. The control panel 75A and the power supply 740, the power supply 74 is connected to the capacitive touch panel 75 to supply power to the capacitive touch panel 75Q. The electronic device can be a mobile phone, 201011620 digital phase Machine, personal digital assistant, notebook computer, desktop computer, television, satellite navigation, on-board display, aviation display or portable digital video disc (DVD) player, etc. The present invention has been described with respect to the preferred embodiments, but the description is intended to be illustrative only and not to limit the scope of the invention. The scope of protection is defined by the scope of the patent application and is not limited to the specific form disclosed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are schematic diagrams showing the sensing positions of two capacitive touch panels; FIG. 3 is a block diagram showing a sensing circuit in the prior art; 4 is a block diagram showing a sensing circuit according to the present invention; FIG. 5 is a circuit diagram showing a first embodiment according to FIG. 4; and FIG. 6 is a second embodiment according to FIG. And the circuit diagram comprises a capacitive touch panel, wherein the valley touch panel comprises a sensing circuit according to the present invention. [Description of main component symbols] Node sensing circuit sensing unit sensing signal generating unit integrator Capacitive touch panel sensing signal section 1-6 100, 400, 500, 600 102, 512, 612 104, 514, 614 106 406, 506, 606 150 '250, 750 411, 511, 611 15 201011620 421, 521, 621 reference signal portion 440, 540, 640 common voltage electrode 510 > 610 sensing signal path 518 > 618 first filter 520, 620 reference signal path 522, 622 reference unit 524, 624 reference signal generating unit 528, 628 second filter 530, 630 amplification unit 532 first differential amplifier 534 second differential amplifier 536, 636 ground matching unit 700 electronic Device 740 power supply

Ri -Re C1-C4

Cpar, Cpari, Cpar3, Cpar5 ❹

Cpar2, Cpar4, Cpar6

Csense ' Ctrans

Ctrans

Cc1 CC2 SWi

St

Snoise

Snoise first resistance - eighth resistance first capacitance - fourth capacitance parasitic capacitance capacitance sensing capacitance sensing unit is not touched when the capacitor first coupling capacitance second coupling capacitance switch sensing signal noise reference signal 16 201011620 S 〇ut

Xi-X4 > Y1-Y4 output signal sensing line

17

Claims (1)

201011620 • VII. Patent application scope: 1. A sensing circuit for a capacitive touch panel, comprising: a sensing signal portion for determining a capacitance value of the capacitive touch panel and receiving a noise. To generate a sensing signal, the capacitance value of the capacitive touch panel is different when it is touched and not touched; a reference signal portion is configured to receive the noise and rotate a reference signal, the reference The signal portion has the same electrical condition as the sensing signal portion; and an integrator 'for receiving the sensing signal and the reference signal, subtracting the sensing signal and the reference signal, and generating an output signal. 2. The sensing circuit of claim 1, wherein the reference signal portion has a capacitance value that is substantially equal to a capacitance value when the sensing signal portion is not touched. The sensing circuit of claim 1, wherein the reference signal portion has electronic components connected to simulate an equivalent circuit of the sensing signal portion. 4. The sensing circuit of claim 1, wherein the integrator φ comprises: a first differential amplifier having an inverting input, a non-inverting input, and an output node; a resistor having a first terminal coupled to the sensing signal portion and a second terminal coupled to the inverting input terminal; and a first capacitor having a first terminal coupled to the inverting input terminal And a second end coupled to the output node. The sensing circuit of claim 4, wherein the integrator further comprises a grounding matching unit, the grounding matching unit comprising: a second resistor having a first end coupled to the reference signal portion 'and a 18 201011620 second end coupled to the non-inverting input; and a second capacitor 'having - the first end coupled to the non-inverting input terminal, and a second end coupled to a ground end The resistance value of the second resistor is substantially equal to the resistance value of the first resistor, and the capacitance value of the second capacitor is substantially equal to the capacitance value of the first capacitor. 6. The sensing circuit of claim 1, wherein: the sensing signal portion comprises: a sensing unit that receives the noise via a parasitic capacitance, the sensing unit having - a first equivalent capacitance value or a second equivalent capacitance value, the first equivalent capacitance value is a capacitance value when the capacitive touch panel is touched, and an equivalent capacitance value of the capacitance value of the capacitance, the first The second equivalent capacitance value is the capacitance value of the capacitive touch panel when not touched and the equivalent capacitance value of the capacitance value of the parasitic capacitance; and a sensing signal generating unit is coupled to the sensing unit, according to The first equivalent capacitance value and the noise, or the sensing signal is generated according to the second equivalent capacitance value and the noise; and the reference signal portion includes: a reference unit that receives the noise and has a a third equivalent capacitance value, the third equivalent capacitance value is an equivalent capacitance value simulating a capacitance value when the capacitive touch panel is not touched and a capacitance value of the parasitic capacitance; and a reference signal generating unit, Coupled to the reference unit, root The reference signal is output according to the third equivalent capacitance value and the noise, wherein the reference soap cell has the same circuit as the sensing unit, and the reference signal generating unit has the same circuit as the sensing signal generating unit. 7. The sensing circuit of claim 6, wherein: the sensing signal portion further comprises a first filter coupled between the sensing signal and the integrator; Filtering the high frequency portion of the sensing signal generated by the sensing signal generating unit; and the reference signal portion further includes a second filter coupled between the reference signal generating unit and the integrator, and The circuit of the second filter is the same as the circuit of the first filter for filtering the high frequency portion of the reference signal. 8. The sensing circuit of claim 6, comprising: a first coupling capacitor, a control signal coupled to the sensing signal generating unit via the first coupling capacitor; and a second coupling capacitor The control signal is coupled to the reference signal generating unit via the second coupling capacitor, wherein the capacitance of the first coupling capacitor is substantially equal to the capacitance of the second coupling capacitor. The sensing circuit of claim 6, wherein the reference unit comprises a capacitor, the capacitance value of the capacitor is substantially equal to the capacitance of the parasitic capacitor, and the noise is coupled through the capacitor To the reference unit. 10. The sensing circuit of claim 4, further comprising an amplification unit coupled to the integrator for amplifying the output signal generated by the integrator. A sensing circuit for a capacitive touch panel, comprising: a sensing signal path for generating a sensing signal based on a capacitance value of the capacitive touch panel and receiving a noise The capacitance value of the capacitive touch panel is different when it is touched and not touched; a reference signal path is used to receive the noise and output a reference signal, the reference signal path having the sensing signal path The same electrical condition; and a first differential amplifier for receiving the sensing signal and the reference signal subtracting the sensing signal and the reference signal, and generating an output signal. The sensing circuit of claim 11, wherein the reference signal path has a capacitance value that is substantially equal to a capacitance value when the sensing signal path is not touched. 13. The sensing circuit of claim 11, wherein the reference signal path has electronic components that are coupled to simulate an equivalent circuit of the sensing signal path. 14. The sensing circuit of claim 11, wherein: the sensing signal path comprises: Φ a sensing unit that receives the noise via a parasitic capacitance, the sensing unit having a first government a capacitance value or a second equivalent capacitance value, the first equivalent capacitance value is a capacitance value when the electric valley touch panel is touched, and an equivalent capacitance value of a capacitance value of the parasitic capacitance, the second class The capacitance value is an equivalent value of the capacitance value of the capacitive touch panel when not touched and the capacitance value of the parasitic capacitance; a sensing signal generating unit coupled to the sensing unit, according to the first And the noise is generated according to the second equivalent capacitance value and 0; the first resistor has a first end coupled to the sensing signal generating unit And a second end coupled to the inverting input of the first differential amplifier; and a first capacitor having a first end coupled to the inverting input of the first differential amplifier, and a second The end is coupled to the output of the first differential amplifier And the reference signal path includes: a reference unit that receives the noise and has a third equivalent capacitance value, and the third equivalent capacitance value simulates a capacitance value of the 21 201011620 when the capacitive touch panel is not touched And an equivalent capacitance value of the capacitance value of the parasitic capacitance; a reference signal generating unit is connected to the reference unit, and the reference signal is output according to the third equivalent capacitance value and the noise; a first end is coupled to the reference signal generating unit, and a second end is coupled to the non-inverting input end of the first differential amplifier; and a second capacitor having a first end coupled to the first a non-inverting input terminal of the differential amplifier and a second terminal coupled to the ground, wherein the reference unit has the same circuit as the sensing unit, and the reference signal generating unit has the same function as the sensing signal generating unit In the circuit, the resistance value of the second resistor is substantially equal to the resistance value of the first resistor, and the capacitance value of the second capacitor is substantially equal to the capacitance value of the first capacitor. 15. The sensing circuit of claim 14, wherein: the sensing signal path further comprises a first filter coupled to the sensing signal generating unit and the first end of the first resistor The high frequency portion of the sensing signal generated by the sensing signal generating unit is filtered out; and the reference signal path further includes a second filter connected to the reference signal generating unit and the first Between the first ends of the two resistors, and the circuit of the second filter is the same as the circuit of the first filter, for filtering the high frequency portion of the reference signal. 16. The sensing circuit of claim 14, comprising: a first coupling capacitor, a control signal coupled to the sensing signal generating unit via the first coupling capacitor; and a second coupling capacitor, The control signal is coupled to the reference signal generating unit via the second coupling capacitor, wherein a capacitance value of the first coupling capacitor is substantially equal to a capacitance value of the second coupling capacitor. The sensing circuit of claim 14, wherein the reference unit comprises a capacitor whose capacitance value is substantially equal to a capacitance value of the parasitic capacitance, and the noise system transmits the Capacitively coupled to the reference unit. 18. The sensing circuit of claim 2, further comprising an amplifying unit coupled to the first differential amplifier for amplifying the output signal generated by the first differential amplifier. An electronic device comprising: a capacitive touch panel comprising: the sensing circuit according to claim 1 or the item Φ1, wherein the electronic device is a mobile phone, a digital camera, and a number of people Assistant, a notebook computer, a desktop computer, a television, a satellite navigation, a car display, an aviation display or a portable digital video disc player. Reference 23