TWI768996B - Capacitance touch sensor and capacitance touch sensing method - Google Patents

Abstract

A capacitance touch sensor and a capacitance touch sensing method for reducing noise induced by a display screen are disclosed. The capacitance touch sensing method includes steps of: (a) during a charge transfer period, performing voltage division on the noise induced by the display screen; and (b) AC coupling the voltage-divided noise to a positive input terminal of a charge amplifier to reduce common-mode noise and increase signal-noise ratio (SNR) of capacitance touch sensing.

Description

Capacitive touch sensor and capacitive touch sensing method

The present invention relates to capacitive sensing, and more particularly, to a capacitive touch sensor with a noise cancellation function and a capacitive touch sensing method.

Please refer to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 respectively illustrate a conventional self-capacitance touch panel TP that is attached to or embedded in an active matrix organic light emitting diode (AMOLED) display screen and the same. A schematic diagram of the self-capacitive touch sensing circuit 2 . As shown in FIG. 1 and FIG. 2 , the noise NO from the cathode of the AMOLED display screen will be coupled to the negative input terminal - of the charge amplifier CAMP through the parasitic capacitance Cb, thus seriously affecting the self-capacitance touch sensing circuit 2 Signal-to-noise ratio for self-capacitive touch sensing.

Please refer to FIG. 3 and FIG. 4 . FIG. 3 and FIG. 4 respectively illustrate a conventional mutual-capacitance (Mutual-capacitance) touch panel TP that is attached to or embedded in an active matrix organic light emitting diode (AMOLED) display screen and the same. A schematic diagram of the mutual capacitance touch sensing circuit 4 . As shown in FIG. 3 and FIG. 4 , the noise NO from the cathode of the AMOLED display screen will be coupled to the negative input terminal - of the charge amplifier CAMP through the parasitic capacitance Cb, thus seriously affecting the mutual capacitance touch sensing circuit 4 Signal-to-noise ratio for mutual capacitive touch sensing.

As can be seen from the above, the conventional capacitive touch sensing circuit externally mounted or embedded in the active matrix organic light emitting diode (AMOLED) display screen is easily affected by the noise caused by the AMOLED display screen, especially from the AMOLED display screen. Affected by the noise of the cathode, the signal-to-noise ratio (SNR) of capacitive touch sensing is poor, which needs to be improved.

In view of this, the present invention provides a capacitive touch sensor with a noise cancellation function and a capacitive touch sensing method to solve the aforementioned problems encountered in the prior art.

One aspect of the present invention includes self-capacitive touch sensing circuits, systems, devices, and components.

Another scope of the present invention includes mutual capacitance touch sensing circuits, systems, devices, and components.

Yet another scope of the present invention includes capacitive touch sensing circuits, systems, devices, and components embedded in AMOLED display screens.

Yet another scope of the present invention includes capacitive touch sensing circuits, systems, devices, and components integrated with AMOLED display driver circuits.

A specific embodiment according to the present invention is a capacitive touch sensing method. In this embodiment, the capacitive touch sensing method is used to eliminate noise caused by the display screen. The capacitive touch sensing method includes the following steps: (a) dividing the noise caused by the display screen during charge transfer; and (b) AC coupling the divided noise to the positive input terminal of the charge amplifier , to eliminate common-mode noise and improve the signal-to-noise ratio of capacitive touch sensing.

Another embodiment according to the present invention is a capacitive touch sensor. In this embodiment, the capacitive touch sensor is used to eliminate noise caused by the display screen. The capacitive touch sensor includes a charge amplifier and a noise cancellation circuit. The noise elimination circuit includes an input end, an output end, a first resistor, a second resistor and a capacitor, the first resistor and the second resistor are connected in series between the input end and the ground end, one end of the capacitor is coupled to the output end and the other end is coupled between the first resistor and the second resistor. During the charging period, the touch pad on the panel is charged to the working voltage or the ground voltage, and the positive input terminal of the charge amplifier is coupled to the reference voltage through the first switch, and the positive input terminal of the charge amplifier is simultaneously coupled to the noise cancellation The output end of the circuit and the input end of the noise elimination circuit are coupled to the first pole of the panel. During the charge transfer, the touch pad on the panel is coupled to the negative input terminal of the charge amplifier through the second switch, the first switch that couples the positive input terminal of the charge amplifier to the reference voltage is disconnected, and the positive input of the charge amplifier is disconnected The terminal is in a floating state, the positive input terminal of the charge amplifier is coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel; and during the charge transfer, the noise The elimination circuit divides the noise of the first pole of the panel through the first resistor and the second resistor, and then AC couples it to the positive input terminal of the charge amplifier in a floating state, so that the voltage of the positive input terminal of the charge amplifier follows the first resistance of the panel. The noise of the first pole of the panel is changed to eliminate the common mode noise generated by the coupling of the noise of the first pole of the panel to the negative input terminal of the charge amplifier through the parasitic capacitance, so as to improve the signal-to-noise ratio of capacitive touch sensing. The ratio of the resistance value of the second resistor is equal to or similar to the ratio of the capacitance value of the feedback capacitance coupled to the charge amplifier and the parasitic capacitance.

In one embodiment, the first electrode of the panel is a cathode or an anode.

In one embodiment, the first resistor and the second resistor in the noise cancellation circuit are replaced by the first capacitor and the second capacitor, the capacitor in the noise cancellation circuit is removed, and the first capacitor and the second capacitor are directly connected to each other. The junction between them is used as the output terminal of the noise cancellation circuit and is coupled to the positive input terminal of the charge amplifier. The capacitance ratio of the first capacitor and the second capacitor is equal to or similar to the parasitic capacitance and the feedback capacitor coupled to the charge amplifier. ratio of capacitance values.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to the input end of the analog buffer, and the output end of the analog buffer is coupled to one end of the capacitor.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to one end of the plurality of capacitors, and the other ends of the plurality of capacitors are respectively coupled to the positive inputs of the plurality of charge amplifiers terminal, the noise elimination circuit uses the first resistor and the second resistor to generate a voltage divider, and is AC coupled to the positive input terminals of the plurality of charge amplifiers in the floating state through the plurality of capacitors, so that the positive input terminals of the plurality of charge amplifiers are The voltages of the input terminals vary with the noise of the first pole of the panel respectively, so as to eliminate the common mode noise generated by the noise of the first pole of the panel being coupled to the negative input terminals of the plurality of charge amplifiers through a plurality of parasitic capacitors respectively , to improve the signal-to-noise ratio of capacitive touch sensing.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to the input end of the analog buffer, and the output end of the analog buffer is coupled to one end of the plurality of capacitors.

In one embodiment, the first resistor and the second resistor in the noise elimination circuit are replaced with a first capacitor and a second capacitor, and the ratio of the capacitance values of the first capacitor and the second capacitor is equal to or similar to the parasitic capacitance and coupling. Capacitance ratio of the feedback capacitor of the charge amplifier.

Another embodiment according to the present invention is a capacitive touch sensor. In this embodiment, the capacitive touch sensor is used to eliminate noise caused by the display screen. The capacitive touch sensor includes a driving circuit and a capacitive sensing circuit. The capacitance sensing circuit is coupled to the driving circuit. The capacitive sensing circuit includes a charge amplifier and a noise cancellation circuit. The noise elimination circuit includes an input end, an output end, a first resistor, a second resistor and a capacitor, the first resistor and the second resistor are connected in series between the input end and the ground end, one end of the capacitor is coupled to the output end and the other end is coupled between the first resistor and the second resistor. During charging, at least one touch driving channel on the panel is charged to a working voltage or ground voltage and a touch sensing channel on the panel is charged to a reference voltage, and the positive input terminal of the charge amplifier is coupled to the reference through the first switch The positive input terminal of the charge amplifier is simultaneously coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel. During the charge transfer, the touch driving channel is charged to the working voltage or the ground voltage, and the touch sensing channel is re-coupled to the negative input terminal of the charge amplifier, and the positive input terminal of the charge amplifier is coupled to the first reference voltage A switch is disconnected, so that the positive input terminal of the charge amplifier is in a floating state, the positive input terminal of the charge amplifier is coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel; and During the charge transfer period, the noise elimination circuit divides the noise of the first pole of the panel through the first resistor and the second resistor, and then AC couples it to the positive input terminal of the charge amplifier in the floating state, so that the positive input terminal of the charge amplifier is in a floating state. The voltage of the input terminal changes with the noise of the first pole of the panel, so as to eliminate the common mode noise generated by the coupling of the noise of the first pole of the panel to the negative input terminal of the charge amplifier through the parasitic capacitance, and improve the capacitive touch sensing The signal-to-noise ratio of the first resistor and the second resistor is equal to or similar to the capacitance ratio of the feedback capacitor coupled to the charge amplifier and the parasitic capacitor.

In one embodiment, the first pole of the panel is a cathode or an anode.

In one embodiment, the first resistor and the second resistor in the noise cancellation circuit are replaced by the first capacitor and the second capacitor, the capacitor in the noise cancellation circuit is removed, and the first capacitor and the second capacitor are directly connected to each other. The contact between them is used as the output terminal of the noise cancellation circuit and is coupled to the positive input terminal of the charge amplifier.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to the input end of the analog buffer, and the output end of the analog buffer is coupled to one end of the capacitor.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to one end of the plurality of capacitors, and the other ends of the plurality of capacitors are respectively coupled to the positive inputs of the plurality of charge amplifiers terminal, the noise elimination circuit uses the first resistor and the second resistor to generate a voltage divider, and is AC coupled to the positive input terminals of the plurality of charge amplifiers in the floating state through the plurality of capacitors, so that the positive input terminals of the plurality of charge amplifiers are The voltages of the input terminals vary with the noise of the first pole of the panel respectively, so as to eliminate the common mode noise generated by the noise of the first pole of the panel being coupled to the negative input terminals of the plurality of charge amplifiers through a plurality of parasitic capacitors respectively , to improve the signal-to-noise ratio of capacitive touch sensing.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to the input end of the analog buffer, and the output end of the analog buffer is coupled to one end of the plurality of capacitors.

In one embodiment, the first resistor and the second resistor in the noise cancellation circuit are replaced by the first capacitor and the second capacitor.

Another embodiment according to the present invention is a capacitive touch sensor. In this embodiment, the capacitive touch sensor is used to eliminate noise caused by the display screen. The capacitive touch sensor includes a driving circuit and a capacitive sensing circuit. The capacitance sensing circuit is coupled to the driving circuit. The capacitive sensing circuit includes a charge amplifier, an output analog buffer and a noise cancellation circuit. The noise elimination circuit includes a first input terminal, a first output terminal, a first resistor, a second resistor, a first capacitor, a second input terminal, a second output terminal, a third resistor, a fourth resistor and a second capacitor. A resistor and a second resistor are connected in series between the first input terminal and the ground terminal. One end of the first capacitor is coupled to the first output terminal and the other end is coupled between the first resistor and the second resistor. The third resistor is connected in series with the fourth resistor between the second input terminal and the ground terminal, one end of the second capacitor is coupled to the second output terminal and the other end is coupled between the third resistor and the fourth resistor; during charging, the At least one touch driving channel on the panel is charged to the first driving voltage and the touch sensing channel on the panel is charged to the reference voltage, the positive input terminal of the charge amplifier is coupled to the reference voltage through the first switch, and the positive input terminal of the charge amplifier is The input terminal is simultaneously coupled to the first output terminal of the noise cancellation circuit, and the first input terminal of the noise cancellation circuit is coupled to the first pole of the panel; during the charging period, the output of the driving voltage source of the driving channel is also analog buffered The positive input terminal of the device is coupled to the driving reference voltage through the second switch, and the positive input terminal of the output analog buffer is simultaneously coupled to the second output terminal of the noise cancellation circuit; during the charge transfer period, the touch drive channel is connected to the The three switches are coupled to the second driving voltage, and at the same time, the touch sensing channel is re-coupled to the negative input terminal of the charge amplifier, and the positive input terminal of the charge amplifier is coupled to the first switch of the reference voltage. The positive input terminal is in a floating state, the positive input terminal of the charge amplifier is coupled to the first output terminal of the noise cancellation circuit, and the first input terminal of the noise cancellation circuit is coupled to the first pole of the panel; during the charge transfer period, The positive input terminal of the output analog buffer is also coupled to the second switch for driving the reference voltage, so that the positive input terminal of the output analog buffer is in a floating state, and the positive input terminal of the output analog buffer is coupled to the noise cancellation The second output end of the circuit, the second input end of the noise elimination circuit is coupled to the first pole of the panel; during the charge transfer period, the noise elimination circuit transmits the noise of the first pole of the panel through the first resistor and the second After the resistor divides the voltage, it is AC coupled to the positive input terminal of the charge amplifier in the floating state, so that the voltage of the positive input terminal of the charge amplifier changes with the noise of the first pole of the panel, so as to eliminate the noise of the first pole of the panel through the The common-mode noise generated by the parasitic capacitance coupled to the negative input terminal of the charge amplifier improves the signal-to-noise ratio of capacitive touch sensing; during the charge transfer, the noise cancellation circuit transmits the noise of the first pole of the panel through the third The resistor and the fourth resistor are divided and AC coupled to the positive input terminal of the output analog buffer in a floating state, so that the voltage of the positive input terminal of the output analog buffer changes with the noise of the first pole of the panel, so as to eliminate the panel The noise of the first pole is coupled to the common mode noise generated by the negative input terminal of the charge amplifier through the parasitic capacitance, which improves the signal-to-noise ratio of capacitive touch sensing. The first driving voltage and the second driving voltage have different potentials. The ratio of the resistance values of the first resistor and the second resistor is equal to or similar to the ratio of the capacitance value of the feedback capacitor coupled to the charge amplifier and the parasitic capacitor, and the resistance value of the third resistor and the fourth resistor The ratio is equal to or similar to the ratio of the capacitance value of the feedback capacitance coupled to the charge amplifier to the parasitic capacitance.

In one embodiment, the first electrode of the panel is a cathode or an anode.

In one embodiment, the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to one end of the plurality of first capacitors and the second capacitor, and the other ends of the plurality of first capacitors are respectively coupled to The positive input terminals of the plurality of charge amplifiers are connected, and after the noise elimination circuit uses the first resistor and the second resistor to generate a voltage divider, the plurality of first capacitors and the second capacitor are respectively AC coupled to the plurality of floating state The positive input terminal of the charge amplifier and the positive input terminal of the output analog buffer make the voltage of the positive input terminal of the plurality of charge amplifiers and the positive input terminal of the output analog buffer respectively change with the noise of the first pole of the panel, Noise is eliminated by simultaneously dithering the second driving voltage and the voltages of the positive input terminals of the plurality of charge amplifiers.

In one embodiment, by separately adjusting the ratio of the resistance values of the first resistor and the second resistor in the noise cancellation circuit to adjust the magnitude of the noise of the plurality of voltages at the positive input terminals of the plurality of charge amplifiers, and to adjust the noise separately The ratio of the resistance values of the third resistor and the fourth resistor in the elimination circuit is used to adjust the noise level of the second driving voltage, so as to optimize the noise elimination effect.

Compared with the prior art, the capacitive touch sensor and the capacitive touch sensing method of the present invention utilize a charge amplifier to divide the noise of the cathode or anode of the AMOLED display screen through a resistor or a capacitor and then AC couple it during charge transfer. to the positive input terminal of the charge amplifier, so as to achieve the specific effect of eliminating common mode noise and improving the signal-to-noise ratio of capacitive touch sensing.

The advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

The term "coupled" as used throughout the specification of the present invention (including the scope of the claims) may refer to any direct or indirect means of connection. For example, if it is described in the text that the first device is coupled to the second device, it should be interpreted that the first device can be directly connected to the second device, or the first device can be indirectly connected to the first device through other devices or some connection means. Second device.

According to an embodiment of the present invention, a capacitive touch sensor is provided. In this embodiment, the capacitive touch sensor can be applied to the AMOLED display screen to eliminate the noise caused by the AMOLED display screen, and it can be a self-capacitive touch sensing circuit or a mutual-capacitive touch sensing circuit , but not limited to this.

Please refer to FIG. 5 , which is a schematic diagram of the capacitive touch sensor in this embodiment during charging and transferring. As shown in FIG. 5 , the capacitive touch sensor 5 is a self-capacitive touch sensor, which includes a charge amplifier CAMP and a noise cancellation circuit NCC. The noise cancellation circuit NCC includes a first resistor R1, a second resistor R2 and a capacitor Cnc. The first resistor R1 and the second resistor R2 are connected in series between the cathode CAT of the AMOLED display screen and the ground terminal. One end of the capacitor Cnc is coupled to the positive input end + of the charge amplifier CAMP and the other end is coupled between the first resistor R1 and the second resistor R2.

During the charging period, the touch pad on the panel is charged to the operating voltage VDD or the ground voltage (GND), and the positive input terminal + of the charge amplifier CAMP is coupled to the reference voltage VREF through the switch W1, and the positive input terminal of the charge amplifier CAMP +At the same time, it is coupled to the output terminal of the noise cancellation circuit NCC, and the input terminal of the noise cancellation circuit NCC is coupled to the cathode CAT of the AMOLED display screen.

During the charge transfer, the touch pad on the panel is coupled to the negative input terminal - of the charge amplifier CAMP through the switch WE, and the switch W1 that couples the positive input terminal + of the charge amplifier CAMP to the reference voltage VREF is disconnected, so that the charge amplifier is turned off. The positive input terminal + of CAMP is in a floating state. The positive input terminal + of the charge amplifier CAMP is coupled to the output terminal of the noise cancellation circuit NCC. The input end of the noise cancellation circuit NCC is coupled to the cathode CAT.

During the charge transfer, the noise cancellation circuit NCC divides the noise NO of the cathode CAT through the first resistor R1 and the second resistor R2, and then AC couples it to the positive input terminal + of the charge amplifier CAMP in a floating state, so that the charge amplifier The voltage VCM of the positive input terminal + of the CAMP changes with the noise NO of the cathode CAT, so as to eliminate the common mode noise (Common mode noise) generated by coupling the noise NO of the cathode CAT to the negative input terminal of the charge amplifier CAMP through the parasitic capacitance Cb. -mode noise), so the signal-to-noise ratio of the capacitive touch sensor 5 for capacitive touch sensing can be improved.

It should be noted that the ratio of the resistance values of the first resistor R1 and the second resistor R2 is equal to or similar to the ratio of the capacitance values of the feedback capacitor Cf coupled to the charge amplifier CAMP and the parasitic capacitor Cb. The reference voltage VREF may be the operating voltage VDD or the ground voltage (GND) or any voltage.

In an embodiment, the first resistor R1 and the second resistor R2 of the noise cancellation circuit NCC in FIG. 5 can also be replaced with the first capacitor C1 and the second capacitor C2 in FIG. 6 , but not limited thereto.

In one embodiment, the first resistor R1 and the second resistor R2 of the noise cancellation circuit NCC in FIG. 5 can also be replaced with the first capacitor C1 and the second capacitor C2 in FIG. 7 . As shown in FIG. 7 , the capacitor Cnc in the noise cancellation circuit NCC is removed, and the junction of the first capacitor C1 and the second capacitor C2 is directly used as the output end of the noise cancellation circuit NCC to be coupled to the charge amplifier CAMP Positive input +. The capacitance ratio of the first capacitor C1 and the second capacitor C2 is equal to or similar to the capacitance ratio of the parasitic capacitor Cb and the feedback capacitor Cf, but not limited thereto.

In one embodiment, as shown in FIG. 8 , the junction between the first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC is coupled to the positive input terminal + of the analog buffer ABF, and the analog buffer ABF The output end of the is coupled to one end of the capacitor Cnc and the negative input end - of the analog buffer ABF, but not limited thereto.

In an embodiment, the first resistor R1 and the second resistor R2 of the noise cancellation circuit NCC in FIG. 8 can also be replaced with the first capacitor C1 and the second capacitor C2 in FIG. 9 , but not limited thereto.

In one embodiment, as shown in FIG. 10 , the junctions between the first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC are respectively coupled to one end of the plurality of capacitors Cnc1 ˜CncN. The other ends of the plurality of capacitors Cnc1 ˜CncN are respectively coupled to the positive input terminals + of the plurality of charge amplifiers CAMP1 ˜CAMPN. After the noise cancellation circuit NCC uses the first resistor R1 and the second resistor R2 to generate a voltage divider, it is AC coupled to the positive input terminals + of the plurality of charge amplifiers CAMP1 to CAMPN in a floating state through the plurality of capacitors Cnc1 to CncN, The voltages VCM of the positive input terminals + of the plurality of charge amplifiers CAMP1 ~ CAMPN are respectively changed with the noise NO of the cathode CAT, so as to eliminate the noise NO of the cathode CAT coupled to the plurality of The negative input terminals of the charge amplifiers CAMP1~CAMPN - generate common mode noise, so the signal-to-noise ratio of capacitive touch sensing can be improved.

In an embodiment, the first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC in FIG. 10 can also be coupled to the positive input terminal + of the analog buffer ABF as shown in FIG. 8 , the analog buffer ABF The output end is coupled to one end of the plurality of capacitors Cnc1~CncN and the negative input end- of the analog buffer ABF, and the first resistor R1 and the second resistor R2 can also be replaced with the first capacitor C1 and the first capacitor C1 and the first resistor R2 in FIG. 9. Two capacitors C2, but not limited thereto.

It should be noted that although the above embodiments are described by taking the cathode CAT of the AMOLED display screen as an example, in fact, the input terminal of the noise cancellation circuit NCC can also be coupled to the anode ANO of the AMOLED display screen, as shown in FIG. 11 . , but not limited to this.

Referring to FIG. 12 , in another embodiment, the capacitive touch sensor 12 is a mutual capacitance touch sensor, which includes a driving circuit and a capacitive sensing circuit. The capacitance sensing circuit includes a charge amplifier CAMP and a noise cancellation circuit NCC. The noise cancellation circuit NCC includes a first resistor R1, a second resistor R2 and a capacitor Cnc. The first resistor R1 and the second resistor R2 are connected in series between the cathode CAT of the AMOLED display screen and the ground terminal. One end of the capacitor Cnc is coupled to the positive input terminal + of the charge amplifier CAMP and the other end is coupled to the first resistor R1 and the ground terminal. between the second resistor R2.

During charging, at least one touch driving channel CHTX on the panel is charged to the working voltage VDD or ground voltage (GND) and the touch sensing channel CHRX on the panel is charged to the reference voltage VREF. The positive input terminal + of the charge amplifier CAMP is coupled to the reference voltage VREF via the switch W1. The positive input terminal + of the charge amplifier CAMP is simultaneously coupled to the output terminal of the noise cancellation circuit NCC. The input end of the noise cancellation circuit NCC is coupled to the cathode CAT.

During the charge transfer, the touch drive channel CHTX is charged to the working voltage VDD or the ground voltage (GND), and the touch sensing channel CHRX is re-coupled to the negative input terminal - of the charge amplifier CAMP, and the positive terminal of the charge amplifier CAMP is connected to The switch W1 whose input terminal + is coupled to the reference voltage VREF is disconnected, so that the positive input terminal + of the charge amplifier CAMP is in a floating state. The positive input terminal + of the charge amplifier CAMP is coupled to the output terminal of the noise cancellation circuit NCC. The input end of the noise cancellation circuit NCC is coupled to the cathode CAT.

During the charge transfer, the noise cancellation circuit NCC divides the noise NO of the cathode CAT through the first resistor R1 and the second resistor R2, and then AC couples it to the positive input terminal + of the charge amplifier CAMP in a floating state, so that the charge amplifier The voltage VCM of the positive input terminal + of CAMP changes with the noise NO of the cathode CAT, so as to eliminate the common mode noise generated by the coupling of the noise NO of the cathode CAT to the negative input terminal - of the charge amplifier CAMP through the parasitic capacitance Cb. The signal-to-noise ratio of capacitive touch sensing can be improved. The ratio of the resistance values of the first resistor R1 and the second resistor R2 is equal to or similar to the ratio of the capacitance values of the feedback capacitor Cf coupled to the charge amplifier CAMP and the parasitic capacitor Cb.

In practical applications, the first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC are coupled to the input end of the analog buffer ABF, and the output end of the analog buffer ABF is coupled to one end of the capacitor Cnc; The first resistor R1 and the second resistor R2 in the circuit NCC can be replaced with the first capacitor C1 and the second capacitor C2, and the capacitor Cnc in the noise cancellation circuit NCC can be removed to directly connect the first capacitor C1 and the second capacitor Cnc. The junction between the capacitors C2 is used as the output terminal of the noise cancellation circuit NCC and is coupled to the positive input terminal + of the charge amplifier CAMP; the capacitance ratio of the first capacitor C1 and the second capacitor C2 is equal to or similar to the parasitic capacitance Cb and the The ratio of the capacitance value of the feedback capacitor Cf, but not limited to this.

In an embodiment, as shown in FIG. 13 , the junction between the first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC is coupled to one end of a plurality of capacitors Cnc1 ˜ CncN, and the plurality of capacitors Cnc1 The other ends of ~CncN are respectively coupled to the positive input terminals + of a plurality of charge amplifiers CAMP1 ~ CAMPN. After the noise canceling circuit NCC uses the first resistor R1 and the second resistor R2 to generate a voltage divider, the plurality of capacitors Cnc1 ~ CncN communicate with each other. It is coupled to the positive input terminals + of the plurality of charge amplifiers CAMP1 ~ CAMPN in a floating state, so that the voltages VCM of the positive input terminals + of the plurality of charge amplifiers CAMP1 ~ CAMPN are respectively changed with the noise NO of the cathode CAT. Eliminate the common mode noise generated by the noise NO of the cathode CAT coupled to the negative input terminals of the plurality of charge amplifiers CAMP1 ~ CAMPN through the plurality of parasitic capacitors Cb1 ~ CbN respectively, so that the signal noise of capacitive touch sensing can be improved Compare.

It should be noted that although the above embodiments are described by taking the cathode CAT of the AMOLED display screen as an example, in fact, the input terminal of the noise cancellation circuit NCC can also be coupled to the anode ANO of the AMOLED display screen, as shown in FIG. 14 . , but not limited to this.

Referring to FIG. 15 , in another embodiment, the capacitive touch sensor 15 is a mutual capacitance touch sensor, which includes a driving circuit and a capacitive sensing circuit for simultaneously eliminating the touch driving channel CHTX and the touch The noise introduced by the parasitic capacitance Cb of the sensing channel CHRX. The capacitance sensing circuit includes a charge amplifier CAMP, an output analog buffer OABF and a noise cancellation circuit NCC. The noise cancellation circuit NCC includes a first noise cancellation circuit NCC_RX and a second noise cancellation circuit NCC_TX. The first noise cancellation circuit NCC_RX includes a first input terminal, a first output terminal, a first resistor R1, a second resistor R2, and a first capacitor Cnc. The second noise cancellation circuit NCC_TX includes a second input terminal, a second output terminal, a third resistor R1tx, a fourth resistor R2tx and a second capacitor Cnctx. The first resistor R1 and the second resistor R2 are connected in series between the first input terminal of the first noise cancellation circuit NCC_RX and the ground terminal, and the cathode CAT of the AMOLED display screen is coupled to the first input of the first noise cancellation circuit NCC_RX terminal, one terminal of the first capacitor Cnc is the first output terminal of the first noise cancellation circuit NCC_RX, which is coupled to the positive input terminal + of the charge amplifier CAMP and the other terminal is coupled to the first resistor R1 and the second resistor R2 between. The third resistor R1tx and the fourth resistor R2tx are connected in series between the second input terminal of the second noise cancellation circuit NCC_TX and the ground terminal, and the cathode CAT of the AMOLED display screen is coupled to the second input of the second noise cancellation circuit NCC_TX terminal, one terminal of the second capacitor Cnctx is the second output terminal of the second noise cancellation circuit NCC_TX, which is coupled to the positive input terminal + of the output analog buffer OABF and the other terminal is coupled to the third resistor R1tx and the fourth between resistors R2tx.

During the charging, at least one touch driving channel CHTX on the panel is charged to the first driving voltage VFF and the touch sensing channel CHRX on the panel is charged to the reference voltage VREF. The positive input terminal + of the charge amplifier CAMP is coupled to the reference voltage VREF via the switch W1. The positive input terminal + of the charge amplifier CAMP is simultaneously coupled to the first output terminal of the first noise cancellation circuit NCC_RX. The first input terminal of the first noise cancellation circuit NCC_RX is coupled to the cathode CAT.

During charging, the positive input terminal+ of the output analog buffer OABF is also coupled to the driving reference voltage VREFtx through the switch W2, and the positive input terminal+ of the output analog buffer OABF is also coupled to the second noise cancellation circuit NCC_TX. Two output terminals.

During the charge transfer period, the touch driving channel CHTX is coupled to the second driving voltage VEE through the switch WA, the second driving voltage VEE is the output voltage of the output analog buffer OABF, and the touch sensing channel CHRX is re-coupled to The negative input terminal of the charge amplifier CAMP is -, and the positive input terminal of the charge amplifier CAMP is coupled to the reference voltage VREF. + is coupled to the first output terminal of the first noise cancellation circuit NCC_RX, and the first input terminal of the first noise cancellation circuit NCC is coupled to the cathode CAT.

During the charge transfer period, the positive input terminal + of the output analog buffer OABF is also disconnected from the switch W2 which is coupled to the driving reference voltage VREFtx, so that the positive input terminal + of the output analog buffer OABF is in a floating state, and the output analog buffer OABF is in a floating state. The positive input terminal + is coupled to the second output terminal of the second noise cancellation circuit NCC_TX, and the second input terminal of the second noise cancellation circuit NCC_TX is coupled to the cathode CAT, so that the output voltage of the output analog buffer OABF is the second The driving voltage VEE varies with the noise NO of the cathode CAT.

During the charge transfer period, the first noise cancellation circuit NCC_RX divides the noise NO of the cathode CAT through the first resistor R1 and the second resistor R2, and then AC couples it to the positive input terminal + of the charge amplifier CAMP in the floating state, so that the The voltage VCM of the positive input terminal + of the charge amplifier CAMP changes with the noise NO of the cathode CAT, so as to eliminate the common mode noise generated by coupling the noise NO of the cathode CAT to the negative input terminal - of the charge amplifier CAMP through the parasitic capacitance Cb , so the signal-to-noise ratio of capacitive touch sensing can be improved.

During the charge transfer period, the second noise cancellation circuit NCC_TX divides the noise NO of the cathode CAT through the third resistor R1tx and the fourth resistor R2tx and then AC couples it to the positive input terminal + of the output analog buffer OABF in a floating state , so that the voltage VCMTX of the positive input terminal + of the output analog buffer OABF changes with the noise NO of the cathode CAT, so as to eliminate the noise NO of the cathode CAT coupled to the negative input terminal of the charge amplifier CAMP through the parasitic capacitance Cb. Common mode noise, so it can improve the signal-to-noise ratio of capacitive touch sensing.

In practical applications, the first driving voltage VFF and the second driving voltage VEE have different potentials; the ratios of the resistance values of the first resistor R1 and the second resistor R2 are equal to or similar to the feedback capacitor Cf and the parasitic capacitor coupled to the charge amplifier CAMP The capacitance ratio of Cb; the resistance ratio of the third resistor R1tx and the fourth resistor R2tx is equal to or similar to the capacitance ratio of the feedback capacitor Cf coupled to the charge amplifier CAMP and the parasitic capacitor Cb.

In one embodiment, as shown in FIG. 16A and FIG. 16B , the capacitive touch sensor 16 is a mutual capacitive touch sensor, which is used to eliminate a plurality of touch driving channels CHTX1 ˜ CHTXN and a plurality of touch senses at the same time. Measure the noise introduced by multiple parasitic capacitors Cb1~CbN of channels CHRX1~CHRXN. The first resistor R1 and the second resistor R2 in the noise cancellation circuit NCC are coupled to one end of the plurality of first capacitors Cnc1 ˜CncN and the second capacitor Cnctx. The other ends of the plurality of first capacitors Cnc1 ˜CncN are respectively coupled to the positive input terminals + of the plurality of charge amplifiers CAMP1 ˜CAMPN. After the noise cancellation circuit NCC uses the first resistor R1 and the second resistor R2 to generate a voltage divider, the plurality of first capacitors Cnc1 to CncN and the second capacitor Cnctx are respectively AC coupled to the plurality of charge amplifiers CAMP1 in a floating state The positive input terminal + of ~CAMPN and the positive input terminal + of the output analog buffer OABF make the voltage VCM of the positive input terminal + of the plurality of charge amplifiers CAMP1~CAMPN and the voltage VCMTX of the positive input terminal + of the output analog buffer OABF respectively vary with the noise NO of the cathode CAT, so that the second driving voltage VEE and the voltage VCM of the positive input terminals + of the plurality of charge amplifiers CAMP1 ˜CAMPN are simultaneously dithered to eliminate noise.

In one embodiment, as shown in FIG. 17A and FIG. 17B , the capacitive touch sensor 17 is a mutual capacitive touch sensor, which is used to simultaneously eliminate a plurality of touch driving channels CHTX1 ˜ CHTXN and a plurality of touch sensors. Measure the noise introduced by multiple parasitic capacitors Cb1~CbN of channels CHRX1~CHRXN. Since the noise cancellation circuit NCC includes the first noise cancellation circuit NCC_RX and the second noise cancellation circuit NCC_TX, and both have different impedance voltage divider circuits, the first resistor R1 and the second resistor can be adjusted separately. The resistance value ratio of R2 is used to adjust the noise level of the plurality of voltages at the positive input terminals + of the plurality of charge amplifiers CAMP1~CAMPN, and the resistance value ratio of the third resistor R1tx and the fourth resistor R2tx is separately adjusted to adjust the second driving voltage. Noise size of VEE to optimize noise removal.

Another specific embodiment according to the present invention is a capacitive touch sensing method. In this embodiment, the capacitive touch sensing method is used to eliminate the noise caused by the AMOLED screen. As shown in FIG. 18, the capacitive touch sensing method includes the following steps:

Step S10: Divide the noise caused by the display screen during the charge transfer; and

Step S12 : AC-couple the voltage-divided noise to the positive input terminal of the charge amplifier to eliminate common-mode noise and improve the signal-to-noise ratio of capacitive touch sensing.

Compared with the prior art, the capacitive touch sensor and the capacitive touch sensing method of the present invention utilize a charge amplifier to divide the noise of the cathode or anode of the AMOLED display screen through a resistor or a capacitor and then AC couple it during charge transfer. to the positive input terminal of the charge amplifier, so as to achieve the specific effect of eliminating common mode noise and improving the signal-to-noise ratio of capacitive touch sensing.

2: Self-capacitive touch sensing circuit

TP: Self Capacitive Touch Panel

PAD: Sensing pad

CSC: Capacitive Sensing Circuit

4: Mutual capacitance touch sensing circuit

TS: Touch Sensor

CAT: Cathode

NO: noise

CAMP: Charge Amplifier

VREF: reference voltage

VOUT: output voltage

Cb: Parasitic capacitance

Cf: feedback capacitor

DRC: drive circuit

TX1~TX8: drive line

RX1~RX8: Sensing line

Cm: Mutual capacitance

CHTX: touch drive channel

CHRX: Touch Sensing Channel

VDD: working voltage

TPAD: Touch Pad

5. 10~17: Capacitive touch sensor

NCC: Noise Cancellation Circuit

R1: first resistor

R2: Second resistor

Cnc: Capacitance

+: positive input

-: negative input

VCM: Voltage

C1: first capacitor

C2: second capacitor

ABF: Analog Buffer

Cnc1~CncN: Capacitance

TPAD1~TPADN: Touch pad

Cb1~CbN: Parasitic capacitance

Cf1~CfN: feedback capacitor

CAMP1~CAMPN: Charge Amplifier

OLED: Organic Light Emitting Diode

ANO: anode

CHTX1~CHTXN: touch drive channel

CHRX1~CHRXN: Touch sensing channel

OABF: Output Analog Buffer

R1tx: the third resistor

R2tx: Fourth resistor

NCC_RX: The first noise cancellation circuit

NCC_TX: Second noise cancellation circuit

Cnctx: Capacitance

VCMTX: Voltage

VREFtx: drive reference voltage

VFF: The first driving voltage

VEE: The second driving voltage

W1~W2: switch

WA~WF: switch

S10~S12: Steps

The accompanying drawings of the present invention are described as follows: FIG. 1 and FIG. 2 are schematic diagrams of a conventional self-capacitance touch panel and its self-capacitance touch sensing circuit that are attached to or embedded in an AMOLED display screen, respectively. FIG. 3 and FIG. 4 are schematic diagrams of a conventional mutual capacitance touch panel and its mutual capacitance touch sensing circuit that are attached to or embedded in an AMOLED display screen, respectively. FIG. 5 is a schematic diagram illustrating a self-capacitive touch sensing circuit of the capacitive touch sensor in a charging period and a transfer period according to an embodiment of the present invention. 6 to 9 are schematic diagrams of different embodiments of the noise cancellation circuit in the capacitive touch sensor, respectively. FIG. 10 is a schematic diagram of a self-capacitance touch sensing circuit in which the noise cancellation circuit includes a plurality of capacitors coupled to a plurality of charge amplifiers, respectively. 11 is a schematic diagram of a self-capacitive touch sensing circuit of a capacitive touch sensor in a charging period and a transfer period in another embodiment of the present invention. 12 is a schematic diagram illustrating a mutual capacitance touch sensing circuit of a capacitive touch sensor in a charging period and a transfer period in another embodiment of the present invention. 13 is a schematic diagram illustrating a mutual capacitance touch sensing circuit in which the noise cancellation circuit includes a plurality of capacitors respectively coupled to a plurality of charge amplifiers. FIG. 14 is a schematic diagram illustrating a mutual capacitance touch sensing circuit of a capacitive touch sensor in a charging period and a transfer period in another embodiment of the present invention. FIG. 15 is a schematic diagram illustrating a mutual capacitance touch sensing circuit of a capacitive touch sensor in a charging period and a transfer period according to another embodiment of the present invention. 16A and 16B are schematic diagrams of a mutual capacitance touch sensing circuit in which the noise cancellation circuit includes a plurality of first capacitors respectively coupled to a plurality of charge amplifiers and a second capacitor coupled to the output analog buffer. 17A and 17B are schematic diagrams illustrating a mutual capacitance touch sensing circuit in which the noise cancellation circuit includes a plurality of capacitors coupled to a plurality of charge amplifiers, respectively. FIG. 18 is a flowchart illustrating a capacitive touch sensing method in another embodiment of the present invention.

S10~S12: Steps

Claims (18)

A capacitive touch sensor for eliminating noise caused by a display screen, the capacitive touch sensor comprising: a charge amplifier; and a noise elimination circuit, including an input end, an output end, a first resistor, a second A resistor and a capacitor, the first resistor and the second resistor are connected in series between the input end and the ground end, one end of the capacitor is coupled to the output end and the other end is coupled to the first resistor and the second resistor between; wherein, during the charging period, the touch pad on the panel is charged to the working voltage or the ground voltage, while the positive input terminal of the charge amplifier is coupled to the reference voltage through the first switch, and the positive input terminal of the charge amplifier is coupled to the reference voltage. The terminal is simultaneously coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel; wherein, during the charge transfer period, the touch pad on the panel is passed through the first pole of the panel. Two switches are coupled to the negative input end of the charge amplifier, and the first switch that is coupled to the positive input end of the charge amplifier to the reference voltage is disconnected, so that the positive input end of the charge amplifier is in a floating state, The positive input terminal of the charge amplifier is coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel; and wherein, during the charge transfer, the noise cancellation circuit is The circuit is AC coupled to the positive input terminal of the charge amplifier in a floating state after the noise of the first pole of the panel is divided by the first resistor and the second resistor, so that the voltage of the positive input terminal of the charge amplifier varies with the voltage of the positive input terminal of the charge amplifier. The noise of the first pole of the panel is changed, so as to eliminate the common mode noise generated by coupling the noise of the first pole of the panel to the negative input terminal of the charge amplifier through parasitic capacitance, and to improve the capacitive touch feeling measured signal-to-noise ratio. The capacitive touch sensor of claim 1, wherein the first electrode of the panel is a cathode or an anode pole. The capacitive touch sensor of claim 2, wherein the first resistor and the second resistor in the noise cancellation circuit are replaced with a first capacitor and a second capacitor, and the noise cancellation circuit The capacitor is removed and the junction between the first capacitor and the second capacitor is directly coupled to the positive input terminal of the charge amplifier as the output terminal of the noise cancellation circuit. The capacitive touch sensor of claim 2, wherein the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to an input end of an analog buffer, the analog buffer The output terminal of the capacitor is coupled to one terminal of the capacitor. The capacitive touch sensor of claim 2, wherein the contact between the first resistor and the second resistor in the noise cancellation circuit is coupled to one end of a plurality of capacitors, and the plurality of capacitors are The other end is respectively coupled to the plurality of output ends, the plurality of output ends are respectively coupled to the positive input ends of the plurality of the charge amplifiers, the noise elimination circuit utilizes the first resistor and the second resistor to generate a voltage divider, The plurality of capacitors are AC-coupled to the positive input terminals of the plurality of charge amplifiers in a floating state, so that the voltages of the positive input terminals of the plurality of charge amplifiers change with the noise of the first pole of the panel respectively, so as to eliminate the The noise of the first pole of the panel is respectively coupled to the common mode noise generated by the negative input terminals of the plurality of charge amplifiers through the plurality of parasitic capacitors, so as to improve the signal-to-noise ratio of capacitive touch sensing. The capacitive touch sensor of claim 5, wherein the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to an input end of an analog buffer, the analog buffer The output end of the is coupled to one end of the plurality of capacitors. The capacitive touch sensor as claimed in any one of claims 2, 4 to 6, wherein the first resistor and the second resistor in the noise cancellation circuit are replaced with a first capacitor and a second capacitor . A capacitive touch sensor for eliminating noise caused by a display screen, the capacitive touch sensor comprising: a driving circuit; and a capacitive sensing circuit coupled to the driving circuit, the capacitive sensing circuit comprising: a charge amplifier; and a noise elimination circuit, including an input end, an output end, a first resistor, a second resistor and a capacitor, the first resistor and the second resistor are connected in series between the input end and the ground end, and the capacitor One end is coupled to the output end and the other end is coupled between the first resistor and the second resistor; wherein, during the charging period, at least one touch driving channel on the panel is charged to a working voltage or a ground voltage and The touch sensing channel on the panel is charged to a reference voltage, the positive input terminal of the charge amplifier is coupled to the reference voltage through the first switch, and the positive input terminal of the charge amplifier is simultaneously coupled to the noise elimination circuit. an output end, the input end of the noise elimination circuit is coupled to the first pole of the panel; wherein, during the charge transfer period, the touch drive channel is charged to the working voltage or the ground voltage, and the touch sense The test channel is changed to be coupled to the negative input end of the charge amplifier, the positive input end of the charge amplifier is coupled to the first switch of the reference voltage, and the first switch of the reference voltage is disconnected, so that the positive input end of the charge amplifier is in a floating state, the charge The positive input terminal of the amplifier is coupled to the output terminal of the noise cancellation circuit, and the input terminal of the noise cancellation circuit is coupled to the first pole of the panel; and wherein, during the charge transfer, the noise cancellation circuit will The noise of the first pole of the panel is divided by the first resistor and the second resistor and then AC coupled to the charge discharger in the floating state The positive input terminal of the amplifier makes the voltage of the positive input terminal of the charge amplifier change with the noise of the first pole of the panel, so as to eliminate the noise of the first pole of the panel from being coupled to the charge amplifier through parasitic capacitance The common-mode noise generated by the negative input terminal of the sensor improves the signal-to-noise ratio of capacitive touch sensing. The capacitive touch sensor of claim 8, wherein the first electrode of the panel is a cathode or an anode. The capacitive touch sensor of claim 9, wherein the first resistor and the second resistor in the noise cancellation circuit are replaced with a first capacitor and a second capacitor, and the noise cancellation circuit The capacitor is removed and the junction between the first capacitor and the second capacitor is directly coupled to the positive input terminal of the charge amplifier as the output terminal of the noise cancellation circuit. The capacitive touch sensor of claim 9, wherein the junction between the first resistor and the second resistor in the noise cancellation circuit is coupled to an input end of an analog buffer, the analog buffer The output terminal of the capacitor is coupled to one terminal of the capacitor. The capacitive touch sensor of claim 9, wherein the contact between the first resistor and the second resistor in the noise cancellation circuit is coupled to one end of a plurality of capacitors, and the plurality of capacitors are The other end is respectively coupled to a plurality of the output ends, the output ends of the noise elimination circuit are respectively coupled to the positive input ends of a plurality of the charge amplifiers, the noise elimination circuit utilizes the first resistor and the second resistor to generate a voltage divider , AC-coupled to the positive input terminals of the plurality of charge amplifiers in the floating state through the plurality of capacitors, so that the voltages of the positive input terminals of the plurality of charge amplifiers vary with the noise of the first pole of the panel respectively, In order to eliminate the common mode noise generated by the noise of the first pole of the panel coupled to the negative input terminals of the plurality of charge amplifiers through the plurality of parasitic capacitors, the signal-to-noise ratio of capacitive touch sensing is improved. The capacitive touch sensor of claim 9, wherein the first resistor and the second resistor in the noise cancellation circuit are coupled to an input terminal of an analog buffer, and an output terminal of the analog buffer is coupled to to one end of the plurality of capacitors. The capacitive touch sensor of any one of claims 9, 11 to 13, wherein the first resistor and the second resistor in the noise cancellation circuit are replaced with a first capacitor and a second capacitor . A capacitive touch sensor for eliminating noise caused by a display screen, the capacitive touch sensor comprising: a driving circuit; and a capacitive sensing circuit coupled to the driving circuit, the capacitive sensing circuit comprising: A charge amplifier; an output analog buffer; and a noise elimination circuit, comprising a first input terminal, a first output terminal, a first resistor, a second resistor, a first capacitor, a second input terminal, a second output terminal, and a third resistor , a fourth resistor and a second capacitor, the first resistor and the second resistor are connected in series between the first input terminal and the ground terminal, one end of the first capacitor is coupled to the first output terminal and the other end is coupled connected between the first resistor and the second resistor, the third resistor and the fourth resistor are connected in series between the second input terminal and the ground terminal, and one end of the second capacitor is coupled to the second output and the other end is coupled between the third resistor and the fourth resistor; wherein, during the charging period, at least one touch driving channel on the panel is charged to the first driving voltage and the touch control on the panel is The sensing channel is charged to the reference voltage, the positive input terminal of the charge amplifier is coupled to the reference voltage through the first switch, and the positive input terminal of the charge amplifier is the same as the is coupled to the first output terminal of the noise cancellation circuit, and the first input terminal of the noise cancellation circuit is coupled to the first pole of the panel; wherein, during the charging period, the driving voltage source of the driving channel is also driven The positive input terminal of the output analog buffer is coupled to the driving reference voltage through the second switch, and the positive input terminal of the output analog buffer is simultaneously coupled to the second output terminal of the noise cancellation circuit; wherein, during the charge transfer period , the touch driving channel is coupled to the second driving voltage through the third switch, and meanwhile the touch sensing channel is re-coupled to the negative input end of the charge amplifier, and the positive input end of the charge amplifier is coupled to The first switch of the reference voltage is disconnected, so that the positive input terminal of the charge amplifier is in a floating state, and the positive input terminal of the charge amplifier is coupled to the first output terminal of the noise cancellation circuit. The first input terminal is coupled to the first pole of the panel; wherein, during the charge transfer period, the positive input terminal of the output analog buffer is also coupled to the second switch of the driving reference voltage to be disconnected to make the output The positive input terminal of the analog buffer is in a floating state, the positive input terminal of the output analog buffer is coupled to the second output terminal of the noise cancellation circuit, and the second input terminal of the noise cancellation circuit is coupled to the panel The first pole of the panel; wherein, during the charge transfer period, the noise elimination circuit of the first pole of the panel is divided by the first resistor and the second resistor and then AC-coupled to the floating state of the noise The positive input terminal of the charge amplifier makes the voltage of the positive input terminal of the charge amplifier change with the noise of the first pole of the panel, so as to eliminate the noise of the first pole of the panel from being coupled to the charge amplifier through parasitic capacitance The common-mode noise generated by the negative input terminal of the panel improves the signal-to-noise ratio of capacitive touch sensing; wherein, during the charge transfer period, the noise cancellation circuit transmits the noise of the first pole of the panel through the third The resistor and the fourth resistor are divided and then AC coupled to the positive input terminal of the output analog buffer in a floating state, so that the voltage of the positive input terminal of the output analog buffer varies with the noise on the first pole of the panel. to eliminate the common mode noise generated by coupling the noise of the first pole of the panel to the negative input terminal of the charge amplifier through parasitic capacitance, and to improve the signal-to-noise ratio of capacitive touch sensing, the first driving voltage It has a different potential from the second driving voltage. The capacitive touch sensor of claim 15, wherein the first electrode of the panel is a cathode or an anode. The capacitive touch sensor of claim 16, wherein a contact between the first resistor and the second resistor in the noise cancellation circuit is coupled to a plurality of the first capacitors and the second capacitors one end, the other ends of the plurality of first capacitors are respectively coupled to the plurality of the first input ends, the plurality of the first input ends are respectively coupled to the positive input ends of the plurality of the charge amplifiers, the noise elimination circuit utilizes the After the first resistor and the second resistor generate a voltage divider, the plurality of first capacitors and the second capacitor are respectively AC coupled to the positive input terminals of the plurality of charge amplifiers and the output analog buffer in a floating state. The positive input terminal makes the voltage of the positive input terminal of the plurality of charge amplifiers and the voltage of the positive input terminal of the output analog buffer respectively change with the noise of the first pole of the panel, so that the second driving voltage and the The voltages at the positive input terminals of the plurality of charge amplifiers are simultaneously dithered to eliminate noise. The capacitive touch sensor of claim 16, wherein the noise levels of the plurality of voltages at the positive input terminal of the charge amplifier are adjusted by separately adjusting the ratio of resistance values of the first resistor and the second resistor, and The ratio of the resistance values of the third resistor and the fourth resistor is separately adjusted to adjust the noise level of the second driving voltage, so as to optimize the noise elimination effect.

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