TWI869925B - Capacitance compensation method for display-touch panel and touch sensing and display driving integrated circuit thereof - Google Patents

Abstract

The present invention relates to a capacitance compensation method for a display-touch panel and a touch sensing and display driving integrated circuit thereof. The capacitance compensation method includes providing a touch sensing and display driving integrated circuit, wherein the touch sensing and display driving integrated circuit includes a plurality of display driving terminals and a plurality of touch sensing terminals; a compensation capacitor being disposed on the touch sensing terminals; outputting a first pulse to the display driving terminals when the specific touch sensing terminal of the touch sensing terminals is sensed; delaying a preset time, and outputting a second pulse to a terminal of the compensation capacitor; and detecting the variation of the capacitance of the specific touch sensing terminal on the overlap period of the first pulse and the second pulse.

Description

Capacitance compensation method for display touch panel and touch sensing and display driving integrated circuit using the same

The present invention relates to a touch sensing and display driving technology, and in particular to a capacitance compensation method of a display touch panel and a touch sensing and display driving integrated circuit using the same.

In embedded display touch sensing panels, the display drive common voltage electrode (VCOM) is usually a special electrode that plays the role of a neutral potential regulator when the display screen is displayed. When the display is not driven, the display drive common voltage electrode will be used as a touch electrode. The display panel drive lines are divided into data lines (source lines) and scanning lines (gate lines). These lines will generate a lot of internal parasitic capacitance relative to the display drive common voltage electrode or the panel. The total capacitance of these parasitics is much larger than the touch capacitance change value that the touch sensing unit wants to detect.

Since the display panel drive circuit itself contains a lot of capacitance, when a finger or other conductor is close to the display touch panel, a new capacitance will be formed, called the sensing capacitance. This sensing capacitance will interact with the capacitance in the display panel drive circuit to form an input circuit. Since the capacitance is sensitive to frequency, the stray capacitance of the display panel drive circuit is closely related to the impact of touch sensing.

As the resolution of display touch panels increases, the frequency of touch sensing increases. When the frequency is high, the capacitance of the drive circuit will have a significant impact on touch sensing. This will lead to a decrease in the sensitivity of the display touch panel or problems such as false touch. Therefore, how to offset the parasitic capacitance on the panel is a key factor in reducing the touch function area and improving performance.

The present invention provides a capacitance compensation method for a display touch panel and a touch sensing and display driving integrated circuit using the same, which is used to reduce the influence of the stray capacitance of the panel on the touch control without increasing the internal compensation capacitance of the integrated circuit as much as possible, increase the sensitivity of the touch control, reduce the area of the integrated circuit, and reduce the cost.

The embodiment of the present invention provides a capacitance compensation method for a display touch panel, and the capacitance compensation method for the display touch panel includes the following steps: providing a touch sensing and display drive circuit, wherein the touch sensing and display drive circuit includes a plurality of display drive pins and a plurality of touch sensing pins; the plurality of touch sensing pins are configured with a compensation capacitor; when When a specific touch sensing pin among the plurality of touch sensing pins is touch sensing, a first pulse is first outputted to the plurality of display drive pins; after a predetermined delay, a second pulse is inputted to one end of the compensation capacitor; and during the period when the first pulse and the second pulse overlap, the capacitance change of the specific touch sensing pin is detected.

The embodiment of the present invention further provides a touch sensing and display drive integrated circuit, which includes a plurality of display drive pins, a plurality of touch sensing pins, and a plurality of touch sensing circuits. The plurality of touch sensing pins are configured with a compensation capacitor. The plurality of touch sensing circuits are coupled to the touch sensing pins. When a specific touch sensing pin among the plurality of touch sensing pins is touch sensed, a first pulse is first output for the plurality of display drive pins. After a predetermined delay, a second pulse is input to one end of the compensation capacitor. During the overlap of the first and second pulses, the capacitance change is detected by a touch sensing circuit coupled to a specific touch sensing pin.

According to the capacitance compensation method of the display touch panel and the touch sensing and display driving integrated circuit using the same described in the preferred embodiment of the present invention, one end of the compensation capacitor coupled to the specific touch sensing pin is coupled to the specific touch sensing pin, and the other end of the compensation capacitor coupled to the specific touch sensing pin receives the second pulse.

According to the capacitance compensation method of the display touch panel and the touch sensing and display driving integrated circuit using the same described in the preferred embodiment of the present invention, the above-mentioned specific touch sensing pin is coupled to a touch sensing circuit, wherein the touch sensing circuit includes an amplifier circuit, a first switch circuit and a second switch circuit. The amplifier circuit includes a first input terminal, a second input terminal and an output terminal, wherein the first input terminal of the amplifier circuit is coupled to the compensation capacitor, and the second input terminal of the amplifier circuit is coupled to a reference voltage. The first switch circuit is coupled between the first input terminal of the amplifier circuit and the compensation capacitor. The second switch circuit is coupled between the output terminal of the amplifier circuit and the first input terminal of the amplifier circuit. When the touch sensing circuit is working, the first switch circuit is turned on and the second switch circuit is turned off. When the touch sensing circuit is not working, the first switch circuit is turned off and the second switch circuit is turned on.

According to the capacitance compensation method of the display touch panel and the touch sensing and display driving integrated circuit using the same described in the preferred embodiment of the present invention, the voltage of the first pulse in the first state and the voltage of the second pulse in the first state are equal to the reference voltage.

In summary, the embodiment of the present invention uses a first pulse wave to output to the driving pin during touch detection, thereby charging the driving circuit and reducing the influence of the stray capacitance of the driving circuit on the touch sensing. In addition, a second pulse wave is output at the other end of the compensation capacitor to compensate the stray capacitance of the driving circuit again. And because in the embodiment of the present invention, a phase difference is given between the first pulse wave received by the driving circuit and the second pulse wave received by the compensation capacitor so that the two are not output at the same time, the compensation capacitor can be a relatively small capacitor. The embodiment of the present invention can not only reduce the influence of stray capacitance of the panel on the touch control and increase the sensitivity of the touch control, but also reduce the area of the integrated circuit and reduce the cost.

In order to further understand the technology, means and effects of the present invention, reference may be made to the following detailed description and accompanying drawings, so that the purpose, features and concepts of the present invention can be thoroughly and specifically understood. However, the following detailed description and accompanying drawings are only used for reference and explanation of the implementation of the present invention, and are not used to limit the present invention.

Reference will now be made in detail to exemplary embodiments of the present invention, which are illustrated in the accompanying drawings. Where possible, the same reference numerals are used in the drawings and the specification to refer to the same or similar components. In addition, the exemplary embodiments are only one of the implementation methods of the design concept of the present invention, and the following examples are not intended to limit the present invention.

FIG. 1 is a circuit block diagram of a display touch system of a preferred embodiment of the present invention. Referring to FIG. 1, the display touch system includes a display touch panel 101 and a touch display driving integrated circuit (TDDI IC) 102. The above-mentioned touch sensing and display driving integrated circuit can also be called a touch display integrated circuit (IDC IC). The display touch panel 101 has a plurality of scanning lines 10, a plurality of data lines 11, and a plurality of touch sensing lines 12. In this embodiment, the driving circuit and the touch sensing circuit of the display panel are integrated in the touch sensing and display driving integrated circuit 102.

FIG. 2 is a circuit diagram of a touch sensing and display driving integrated circuit 102 of a preferred embodiment of the present invention. Referring to FIG. 2 , the touch sensing and display driving integrated circuit 102 in this embodiment includes a display driving pin 201, a scan driving pin 202, a touch sensing pin 203, a touch sensing circuit 204, and a multiplexer circuit 205. In this embodiment, the display drive pin 201, the scan drive pin 202, the touch sensing pin 203 and the touch sensing circuit 204 are shown as one set. However, those with ordinary knowledge in the field should know that there are multiple sets of circuits actually used, which will not be described in detail here. Furthermore, since the touch sensing circuit 204 can use time-division multiplexing to detect different touch sensing electrodes one by one when the present embodiment is actually applied, a multiplexing circuit 205 is additionally provided to detect multiple touch sensing electrodes in time-division multiplexing. However, those with ordinary knowledge in the field should know that if the present embodiment does not use time-division multiplexing, the multiplexing circuit 205 can also be omitted.

In the above embodiment, each touch sensing electrode on the panel is used as a common electrode voltage VCOM during the display driving period. During the touch sensing period, each of the above driving lines (including gate driving lines and data driving lines) will generate parasitic capacitance with the circuits related to touch sensing, which are simplified as Csx-gip and Csx-sd in the diagram, where Csx-gip represents the parasitic capacitance caused by the gate driving line and Csx-sd represents the parasitic capacitance caused by the data driving line. The parasitic capacitance Csx-gip caused by the gate drive lines and the parasitic capacitance Csx-sd caused by the data drive lines will affect the operation of the touch sensing circuit 204.

In this embodiment, the touch sensing circuit 204 is implemented in the form of an integrator, for example. In this embodiment, the touch sensing circuit 204 includes an amplifier circuit 21, a first switch circuit 22, a second switch circuit 23, and a feedback capacitor CFB. The amplifier circuit 21 includes a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal of the amplifier circuit 21 is coupled to the compensation capacitor CB, and the second input terminal of the amplifier circuit 21 is coupled to a touch reference voltage VR. The first switch circuit 22 is coupled between the first input terminal of the amplifier circuit 21 and the compensation capacitor CB. The second switch circuit 23 and the feedback capacitor CFB are both coupled in parallel between the output terminal of the amplifier circuit 21 and the first input terminal of the amplifier circuit 21.

FIG. 3 is a diagram showing the operation waveform of the touch sensing and display driving integrated circuit 102 of a preferred embodiment of the present invention. Referring to FIG. 3 , in the initial state T1 , the second switch circuit 23 is in the conducting state. In order to allow the touch sensing circuit 204 to operate normally, in this embodiment, the touch sensing and display driving integrated circuit 102 will first output a first pulse VP to the display driving pin 201 and the scanning driving pin 202 during the touch sensing period T2. The voltage of this first pulse VP is the reference voltage VREF, which is used to reduce or eliminate the effect of the parasitic capacitance Csx-gip caused by the gate driving line and the parasitic capacitance Csx-sd caused by the data driving line. At this time, the multiplexer circuit 205 is turned on, the second switch circuit 23 is turned off, and the first switch circuit 22 is turned on. In addition, a predetermined time ΔT after the reference voltage VREF is output to the display drive pin 201 and the scan drive pin 202, a second pulse VCB is also output to the other end Tc of the compensation capacitor CB. The voltage of the second pulse VCB is the reference voltage VREF. Thus, the touch sensing circuit 204 detects whether the touch electrode has a capacitance change.

In the above embodiment, the display touch sensing and display driving integrated circuit 102 outputs a display control signal such as a full drive signal (such as the above reference voltage VREF) during the touch sensing period, and stores and releases the charge through the parasitic capacitor to compensate and reduce the adverse effects caused by the parasitic capacitor Csx. The reference voltage VREF is output to the compensation capacitor CB after a predetermined time, so the compensation capacitor CB that needs to be designed inside the touch sensing and display driving integrated circuit 102 can be greatly reduced. Generally speaking, the components that occupy a relatively large area inside an integrated circuit are mostly capacitors. This embodiment reduces the capacitance value required for compensating capacitor CB during design to reduce the area of the capacitor, which can greatly reduce the overall area and cost of the integrated circuit. In addition, in this embodiment, the same reference voltage VREF is provided to the display drive pin 201, the scan drive pin 202 and the compensation capacitor CB during the touch sensing period. However, a person skilled in the art should know that different voltage values may be provided to the display drive pin 201, the scan drive pin 202 and the compensation capacitor CB during the touch sensing period. As long as a high voltage is applied to reduce the interference of parasitic capacitance during the touch sensing period, it should be within the scope of the present invention.

FIG. 4 shows an operation waveform diagram of the touch sensing and display driving integrated circuit 102 of a preferred embodiment of the present invention. Please refer to FIG. 3 and FIG. 4. In this embodiment, the touch sensing is divided into a positive half cycle and a negative half cycle. In the positive half cycle, the driving method is the same as above, so it is not repeated here. However, in the negative half cycle, after the end of T1 time, the first pulse VP changes from high voltage to low voltage, and after a predetermined time ΔT, the second pulse VCB changes from high voltage to low voltage.

As can be seen from the embodiments of FIG. 3 and FIG. 4, a phase difference is mainly given between the first pulse wave VP and the second pulse wave VCB, and touch detection is performed during the overlap period. However, the present invention is not limited to this preferred embodiment.

The above embodiments can be summarized into a capacitance compensation method for a display touch panel. FIG. 5 is a flow chart of a capacitance compensation method for a display touch panel according to a preferred embodiment of the present invention. Referring to FIG. 5 , the capacitance compensation method for a display touch panel includes the following steps:

Step S500: Start.

Step S501: providing a touch sensing and display driving circuit, wherein the touch sensing and display driving circuit includes a plurality of display driving pins and a plurality of touch sensing pins.

Step S502: providing a compensation capacitor to be configured at the plurality of touch sensing pins.

Step S503: Determine whether to perform touch sensing. If touch sensing is performed, proceed to step S404.

Step S504: Output a first pulse to the plurality of display drive pins. When the touch sensing pins are touch sensing, firstly output a full drive voltage to the display drive pin 201 and the scan drive pin 202, such as the reference voltage VREF mentioned above.

Step S505: Delay a predetermined time and input a second pulse to one end of the compensation capacitor. As in the above embodiment, after a predetermined time ΔT, the second pulse VCB is output to the other end Tc of the compensation capacitor CB.

Step S506: Detect the capacitance change during the overlap period of the first pulse and the second pulse. As shown in FIG. 3, by detecting the charge Qf change during this period, the capacitance change of the touch electrode can be determined.

Step S507: End.

In summary, the embodiment of the present invention uses a first pulse wave to output to the driving pin during touch detection, thereby charging the driving circuit and reducing the influence of the stray capacitance of the driving circuit on the touch sensing. In addition, a second pulse wave is output at the other end of the compensation capacitor to compensate the stray capacitance of the driving circuit again. And because in the embodiment of the present invention, a phase difference is given between the first pulse wave received by the driving circuit and the second pulse wave received by the compensation capacitor, so that the two are not output at the same time, the compensation capacitor can use a relatively small capacitor. Therefore, the embodiment of the present invention can not only reduce the influence of stray capacitance of the panel on the touch control, increase the sensitivity of the touch control, but also reduce the area of the integrated circuit.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes thereto will be suggested to those skilled in the art and are to be included within the spirit and scope of the present application and the scope of the appended claims.

101: Display touch panel

102: Display drive and touch sensing integrated circuit

10: Scan line

11: Data line

12: Multiple touch sensing lines

201: Display drive pin

202: Scan drive pin

203: Touch sensor pin

204: Touch sensing circuit

205:Multiplex Circuit

Csx-gip: parasitic capacitance caused by gate drive line

Csx-sd: parasitic capacitance caused by data drive line

21: Amplifier circuit

22: First switch circuit

23: Second switch circuit

CFB: Feedback Capacitor

CB: Compensation Capacitor

VREF: Reference voltage

VR: Touch reference voltage

Tc: One end of the compensation capacitor CB

S500-S507: Process steps of a capacitance compensation method for a display touch panel according to a preferred embodiment of the present invention

The accompanying drawings are provided to enable a person with ordinary knowledge in the art to which the present invention belongs to further understand the present invention, and are incorporated into and constitute a part of the specification of the present invention. The accompanying drawings show exemplary embodiments of the present invention, and are used together with the specification of the present invention to explain the principles of the present invention.

FIG. 1 is a block diagram of a touch sensing and display driving integrated circuit of a preferred embodiment of the present invention.

FIG. 2 is a circuit diagram of a touch sensing and display driving integrated circuit according to a preferred embodiment of the present invention.

FIG. 3 shows an operation waveform diagram of a display driving and touch sensing integrated circuit according to a preferred embodiment of the present invention.

FIG. 4 is a diagram showing the operation waveform of a display driving and touch sensing integrated circuit according to a preferred embodiment of the present invention.

FIG. 5 is a flow chart of a capacitance compensation method for a display touch panel according to a preferred embodiment of the present invention.

S500~S507: Process steps of a capacitance compensation method for a display touch panel in a preferred embodiment of the present invention

Claims (10)

A capacitance compensation method for a display touch panel includes: providing a touch sensing and display driving circuit, wherein the touch sensing and display driving circuit includes a plurality of display driving pins and a plurality of touch sensing pins; the plurality of touch sensing pins are configured with a compensation capacitor; when one of the plurality of touch sensing pins When a specific touch sensing pin is touch-sensed, it includes: first outputting a first pulse wave for the above-mentioned multiple display drive pins; delaying a predetermined time and inputting a second pulse wave to one end of the compensation capacitor; and detecting the capacitance change of the specific touch sensing pin during the overlap of the first pulse wave and the second pulse wave. According to the capacitance compensation method of the display touch panel described in claim 1, one end of the compensation capacitor coupled to the specific touch sensing pin is coupled to the specific touch sensing pin, and the other end of the compensation capacitor coupled to the specific touch sensing pin receives the second pulse. According to the capacitance compensation method of the display touch panel described in claim 1, the specific touch sensing pin is coupled to a touch sensing circuit, wherein the touch sensing circuit includes: an amplifier circuit, including a first input terminal, a second input terminal and an output terminal, wherein the first input terminal of the amplifier circuit is coupled to the compensation capacitor, and the second input terminal of the amplifier circuit is coupled to a reference voltage; a first switch circuit , coupled between the first input terminal of the amplifier circuit and the compensation capacitor; and a second switch circuit, coupled between the output terminal of the amplifier circuit and the first input terminal of the amplifier circuit; wherein, when the touch sensing circuit is working, the first switch circuit is turned on and the second switch circuit is turned off, wherein, when the touch sensing circuit is not working, the first switch circuit is turned off and the second switch circuit is turned on. According to the capacitance compensation method of the display touch panel described in claim 3, the voltage of the first pulse in a first state and the voltage of the second pulse in the first state during the overlap period are equal to the reference voltage. According to the capacitance compensation method of the display touch panel described in claim 1, the first pulse wave and the second pulse wave have a phase difference. A touch sensing and display driving integrated circuit includes: a plurality of display driving pins; a plurality of touch sensing pins, wherein the plurality of touch sensing pins are configured with a compensation capacitor; and a plurality of touch sensing circuits coupled to the touch sensing pins; wherein when one of the plurality of touch sensing pins is specifically When the touch sensing pin performs touch sensing, a first pulse is output for the above-mentioned multiple display drive pins, and a second pulse is input to one end of the compensation capacitor after a predetermined delay. During the overlap period of the first pulse and the second pulse, the touch sensing circuit coupled to the specific touch sensing pin detects the capacitance change. According to the touch sensing and display driving integrated circuit described in claim 6, one end of the compensation capacitor coupled to the specific touch sensing pin is coupled to the specific touch sensing pin, and the other end of the compensation capacitor coupled to the specific touch sensing pin receives the second pulse. According to the touch sensing and display driving integrated circuit described in claim 6, the touch sensing circuit includes: an amplifier circuit including a first input terminal, a second input terminal and an output terminal, wherein the first input terminal of the amplifier circuit is coupled to the compensation capacitor, and the second input terminal of the amplifier circuit is coupled to a reference voltage; a first switch circuit coupled between the first input terminal of the amplifier circuit and the compensation capacitor; and a second switch circuit coupled between the output terminal of the amplifier circuit and the first input terminal of the amplifier circuit; wherein when the touch sensing circuit is working, the first switch circuit is turned on and the second switch circuit is turned off, wherein when the touch sensing circuit is not working, the first switch circuit is turned off and the second switch circuit is turned on. According to the touch sensing and display driving integrated circuit described in claim 6, the voltage of the first pulse in a first state and the voltage of the second pulse in the first state during the overlap period are equal to the reference voltage. According to the touch sensing and display driving integrated circuit described in claim 8, a multiplexing circuit is also included between the first switch circuit and the plurality of touch sensing pins corresponding thereto, for switching the plurality of touch sensing pins to perform time-sharing multiplexing touch detection.

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