Touch detection circuit

Abstract

The invention provides a touch detection circuit. The touch detection circuit comprises at least one driving signal generator. The at least one drive signal generator receives a first power supply voltage and a second power supply voltage as an operating power supply. Each of the at least one driving signal generator generates at least one driving signal according to a first power supply voltage and a second power supply voltage, and each of the at least one driving signal swings between a first voltage and a second voltage, where the first voltage is a positive voltage and the second voltage is a negative voltage.

Description

Technical Field

[0001] The present invention relates to a touch detection circuit, and more particularly to a touch detection circuit that can provide a driving scheme for reducing electromagnetic interference (EMI). Background Art

[0002] Due to the development of electric vehicles, the demand for electronic products in the automotive field has been increasing. In automotive applications, reducing electromagnetic interference (EMI) is very important because in addition to navigation and audio-video devices in cars, there are various electronic products. In addition to the broadcast system, there are also various chips that control the operation of the vehicle, such as autonomous driving and driver assistance systems. Therefore, circuit design needs to avoid interference between these different electronic components.

[0003] In automotive touch applications, due to safety issues, the glass cover of the panel will be thicker, and the touch effect will be worse. To enhance the touch effect, the driving signal voltage of the touch detection circuit will become higher, which will bring another problem, that is, the EMI will be more serious.

[0004] Please refer to Figure 9A and Figure 9B , which respectively show the driving signal waveform diagram and frequency response diagram of the touch detection operation of the prior art. In Figure 9A , when the touch sensing operation is started, the driving signal DRV provided by the touch detection circuit may be a sine wave with an amplitude modulation scheme. When the touch sensing operation is not started, the driving signal DRV can be maintained at 0V. It should be noted here that in the prior art, when the touch sensing operation is started, the amplitude of the driving signal DRV is always positive. To provide a sufficient voltage level, the amplitude of the driving signal needs to be increased to a relatively high level, and EMI may occur.

[0005] In Figure 9B , it can be seen that there are many spectra below the frequency TXF of the driving signal DRV, and the amplitude of each spectrum below the frequency TXF is close to or even higher than the amplitude of the spectrum at the frequency TXF. That is to say, the EMI may be very serious. Summary of the Invention

[0006] The present invention is directed to a touch detection circuit that can reduce low-frequency noise interference.

[0007] According to an embodiment of the present invention, the touch detection circuit includes at least one driving signal generator. The at least one driving signal generator receives a first power supply voltage and a second power supply voltage as operating power supplies. Each driving signal generator generates at least one driving signal according to the first power supply voltage and the second power supply voltage, and each driving signal swings between a first voltage and a second voltage, where the first voltage is a positive voltage and the second voltage is a negative voltage.

[0008] Based on the above, the drive signal generator of the touch detection circuit is configured to generate a drive signal that swings between a positive voltage and a negative voltage. That is, the rising amplitude of the drive signal from the disabled state to the enabled state of the drive signal generator may be reduced. Thus, electromagnetic interference (EMI) may be reduced, and the performance of the touch sensing device can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of a touch detection circuit according to an exemplary embodiment is shown.

[0010] Figure 2 A waveform diagram of a drive signal generated by a drive signal generator according to an exemplary embodiment is shown.

[0011] Figure 3 is a frequency response diagram of the drive signal.

[0012] Figure 4 A schematic diagram of a drive signal generator according to an exemplary embodiment is shown.

[0013] Figure 5A A schematic diagram of a drive signal generator according to another exemplary embodiment is shown.

[0014] Figure 5B A schematic diagram of a drive signal generator according to another exemplary embodiment is shown.

[0015] Figure 5C is Figure 5B a waveform diagram of the buffer signal of the drive signal generator 500' of the embodiment.

[0016] Figure 6 A schematic diagram of a touch sensing device according to an exemplary embodiment is shown.

[0017] Figure 7 A waveform diagram of the drive signal of the touch sensing device according to an exemplary embodiment is shown.

[0018] Figure 8 A schematic diagram of a touch sensing operation according to an exemplary embodiment is shown.

[0019] Figure 9A and Figure 9B respectively show a waveform diagram and a frequency response diagram of the drive signal of the prior art touch detection operation. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0021] Please refer toFigure 1 , which shows a schematic diagram of a touch detection circuit according to an exemplary embodiment. The touch detection circuit 100 includes one or more drive signal generators 111-11N, and the drive signal generators 111-11N respectively generate a plurality of drive signals DRV1-DRVN. The drive signal generators 111-11N provide the drive signals DRV1-DRVN to a plurality of touch sensing plates for touch sensing operations. The touch sensing plates can be capacitive touch sensing plates.

[0022] In this embodiment, each of the drive signal generators 111-11N receives a first power supply voltage VP1 and a second power supply voltage VP2 as operating voltages, where the first power supply voltage VP1 can be greater than the second power supply voltage VP2. The first power supply voltage VP1 is a positive power supply voltage, and the second power supply voltage VP2 is a negative voltage. In addition, each of the drive signals DRV1-DRVN generated by each of the drive signal generators 111-11N can swing between a first voltage and a second voltage, where the first voltage is a positive voltage and the second voltage is a negative voltage.

[0023] Please refer to Figure 1 and Figure 2 , where Figure 2 shows a waveform diagram of a drive signal generated by a drive signal generator according to an exemplary embodiment. In Figure 2 , the drive signal DRVx can be any one of the drive signals DRV1-DRVN and can be generated by the corresponding drive signal generator 11x. When the touch sensing operation is started, the drive signal generator 11x can generate a drive signal DRVx having a sine wave during an enable period ENP. In this embodiment, the sine wave of the drive signal DRVx can swing between a first voltage V1 and a second voltage V2, where the first voltage V1 is greater than 0V and the second voltage V2 is less than 0V. In addition, the amplitude of the sine wave of the drive signal DRVx can be modulated. In this embodiment, the amplitude of the sine wave of the drive signal DRVx can increase in the first half of the enable period ENP, and the amplitude of the sine wave of the drive signal DRVx can decrease in the second half of the enable period ENP.

[0024] In this embodiment, the absolute value of the first power supply voltage VP1 received by the drive signal generator 11x is greater than the absolute value of the first voltage V1, and the absolute value of the second power supply voltage VP2 received by the drive signal generator 11x is greater than the absolute value of the second voltage V2. The absolute values of the first voltage V1 and the second voltage V2 can be the same or different. The absolute values of the first power supply voltage VP1 and the second power supply voltage VP2 can also be the same or different.

[0025] On the other hand, when the touch sensing operation is not started, the drive signal generator 11x can generate a drive signal DRVx equal to 0V during a disable period DISP.

[0026] By generating a driving signal DRVx that switches between a first power supply voltage VP1 and a second power supply voltage VP2, the frequency response diagram of the driving signal DRVx can be as Figure 3 shown. In Figure 3 , it can be seen that the amplitude of each spectrum below the frequency TXF of the driving signal DRVx is lower than the amplitude of the spectrum at the frequency TXF. That is to say, the interference of low-frequency noise is reduced, and the performance of the touch sensing device can be enhanced accordingly.

[0027] Note here that the frequency response diagram can be obtained by performing a Fast Fourier Transform (FFT) on the driving signal DRVx.

[0028] Please refer to Figure 4 , which shows a schematic diagram of a driving signal generator according to an exemplary embodiment. The driving signal generator 400 includes a first voltage buffer 411, a second voltage buffer 412, a signal conversion circuit 420, and a third voltage buffer 430. The first voltage buffer 411 is a voltage follower and includes an operational amplifier OP1. The positive input terminal of the operational amplifier OP1 receives a first input signal IN1, and the negative input terminal of the operational amplifier OP1 is coupled to the output terminal of the operational amplifier OP1. The operational amplifier OP1 receives a first power supply voltage VP1 and a ground voltage GND as operating power supplies.

[0029] The second voltage buffer 412 is also a voltage follower and includes an operational amplifier OP2. The positive input terminal of the operational amplifier OP2 receives a second input signal IN2, and the negative input terminal of the operational amplifier OP2 is coupled to the output terminal of the operational amplifier OP2. The operational amplifier OP2 receives a ground voltage GND and a second power supply voltage VP2 as operating power supplies.

[0030] The first voltage buffer 411 is configured to receive the first input signal IN1 and generate a first voltage V1. The second voltage buffer 412 is configured to receive the second input signal IN2 and generate a first voltage V2. In this embodiment, the first voltage V1 can be a positive voltage (greater than 0V), and the second voltage can be a negative voltage (less than 0V).

[0031] In addition, the signal conversion circuit 420 is coupled to the output terminals of the first voltage buffer 411 and the second voltage buffer 412, and receives the first voltage V1 and the second voltage V2 as power supply voltages respectively. The signal conversion circuit 420 also receives an input code CODE and generates a conversion signal CS1 by converting the input code CODE.

[0032] In this embodiment, the signal conversion circuit 420 may be a digital to analog converter (DAC). The input code CODE is a digital code, and the conversion signal CS1 is an analog signal.

[0033] The third voltage buffer 430 is coupled to the first voltage buffer 411, the second voltage buffer 412, and the signal conversion circuit 420. The third voltage buffer 430 receives the first voltage V1 and the second voltage V2 as power supply voltages. The third voltage buffer 430 may be a voltage follower and includes an operational amplifier OP3. The operational amplifier OP3 receives the conversion signal CS1 through its positive input terminal, and the negative input terminal and the output terminal of the operational amplifier OP3 are coupled together. The operational amplifier OP3 generates a drive signal DRV through its output terminal, and the drive signal DRV can swing between the first voltage V1 and the second voltage V2.

[0034] Note that the amplitude of the drive signal DRV can be controlled by the input code CODE. The positive peak value of the drive signal DRV can be equal to or less than the first voltage V1, and the negative peak value of the drive signal DRV can be equal to or greater than the second voltage V2. The input code CODE may be a time-varying code, and the amplitude of the drive signal DRV can be modulated according to the change of the input code CODE, as Figure 2 the shown drive signal DRVx.

[0035] In this embodiment, the first voltage V1 may be 3V, and the first power supply voltage VP1 may be 6V. The second voltage V2 may be -3V, and the second power supply voltage VP1 may be -6V. The first voltage V1 may be half of the first power supply voltage VP1, and the second voltage V2 may be half of the second power supply voltage VP2. Or in some embodiments, the first voltage V1 may be the first power supply voltage VP1 multiplied by N, and the second voltage V2 may be the second power supply voltage VP2 multiplied by M, where N and M are positive real numbers less than 1, and N and M may be the same or different.

[0036] Please refer to Figure 5A, which shows a schematic diagram of a drive signal generator according to another embodiment of the present disclosure. The drive signal generator 500 includes a first signal conversion circuit 511, a second signal conversion circuit 512, a first voltage buffer 521, a second voltage buffer 522, and a multiplexer (Mux) 530. The first signal conversion circuit 511 and the second signal conversion circuit 512 are digital to analog converters (DACs). The first signal conversion circuit 511 receives a first input code IC1 and converts the first input code IC1 to generate a first conversion signal CS1. The second signal conversion circuit 512 receives a second input code IC2 and converts the second input code IC2 to generate a second conversion signal CS2. The first voltage buffer 521 and the second voltage buffer 522 are respectively coupled to the first signal conversion circuit 511 and the second signal conversion circuit 512. The first voltage buffer 521 receives the first conversion signal CS1 and generates a first buffer signal BS1. The second voltage buffer 522 receives the second conversion signal CS2 and generates a second buffer signal BS2.

[0037] Specifically, the first voltage buffer 521 includes an operational amplifier OP1. The operational amplifier OP1 receives a first power supply voltage VP1 and a ground voltage GND as operating power supplies. The first power supply voltage VP1 is a positive voltage. The positive input terminal of the operational amplifier OP1 receives the first conversion signal CS1, and the negative input terminal of the operational amplifier OP1 is coupled to the output terminal of the operational amplifier OP1. The first voltage buffer 521 is a voltage follower and generates a buffer signal BS1 according to the first conversion signal CS1. In this embodiment, the buffer signal BS1 can remain at 0V during some time periods, or can be a sine wave with an amplitude equal to the first voltage V1 during some other time periods, where the first voltage V1 is greater than 0V.

[0038] The second voltage buffer 521 includes an operational amplifier OP2. The operational amplifier OP2 receives a second power supply voltage VP2 and a ground voltage GND as operating power supplies. The second power supply voltage VP2 is a negative voltage. The positive input terminal of the operational amplifier OP2 receives the second conversion signal CS2, and the negative input terminal of the operational amplifier OP2 is coupled to the output terminal of the operational amplifier OP2. The second voltage buffer 522 is also a voltage follower and generates a buffer signal BS2 according to the second conversion signal CS2. In this embodiment, the buffer signal BS2 can remain at 0V during some time periods, or can be a sine wave with an amplitude equal to the second voltage V2 during some other time periods, where the second voltage V2 is less than 0V.

[0039] Note that when the buffer signal BS1 remains at 0V, the buffer signal BS2 is a sine wave with a negative amplitude, and when the buffer signal BS2 remains at 0V, the buffer signal BS1 is a sine wave with a positive amplitude.

[0040] The multiplexer 530 is coupled to the first voltage buffer 521 and the second voltage buffer 522. The multiplexer 530 generates a drive signal DRV by alternately selecting one of the buffer signals BS1 and BS2. Specifically, during the time period ta, the multiplexer 530 selects the buffer signal BS1 to generate the drive signal DRV, and during the time period tb, the multiplexer 530 selects the buffer signal BS2 to generate the drive signal DRV. Thus, the drive signal DRV can be a sine wave that swings between the first voltage V1 and the second voltage V2.

[0041] In addition, the voltage conversion circuits 511 and 512 can be implemented by any digital-to-analog converter known to those skilled in the art, and the multiplexer 530 can also be implemented by any signal multiplexing circuit known to those skilled in the art, and there is no particular limitation here.

[0042] Please refer to Figure 5B , which shows a schematic diagram of a drive signal generator according to another embodiment of the present disclosure. Different from the drive signal generator 500 in Figure 5A , the drive signal generator 500' in Figure 5B further includes a third signal conversion circuit 513, a fourth signal conversion circuit 514, a third voltage buffer 523, and a fourth voltage buffer 524. The third signal conversion circuit 513 and the fourth signal conversion circuit 514 respectively generate conversion signals CS3 and CS4. The third voltage buffer 523 and the fourth voltage buffer 524 respectively receive the conversion signals CS3 and CS4, and respectively generate buffer signals BS3 and BS4. The third voltage buffer 523 and the fourth voltage buffer 524 are both voltage followers. The third voltage buffer 523 and the fourth voltage buffer 524 are respectively formed by operational amplifiers OP3 and OP4. The detailed circuit structures of the first voltage buffer 521 to the fourth voltage buffer 524 are the same, and will not be repeated here.

[0043] Here, please also refer to Figure 5B and Figure 5C , where Figure 5C is the buffer signal waveform diagram of the drive signal generator 500' of the Figure 5B embodiment. In Figure 5C , during the time period ta, the buffer signal BS1 is a sine wave with a positive amplitude; the buffer signal BS2 is a sine wave with a negative amplitude; and the buffer signals BS3 and BS4 remain at 0V. During the time period tb, the buffer signal BS4 is a sine wave with a positive amplitude; the buffer signal BS2 is a sine wave with a negative amplitude; and the buffer signals BS1 and BS2 remain at 0V.

[0044] In this embodiment, there is a first phase difference between the buffer signal BS1 and the buffer signal BS3; there is a second phase difference between the buffer signal BS2 and the buffer signal BS4; the first phase difference may be equal to the second phase difference.

[0045] Please refer back to Figure 5B . In this embodiment, the multiplexer 530 receives the buffer signals BS1 - BS4. The multiplexer 530 can alternately select one of the buffer signals BS1 and BS2 to generate the drive signal DRV1, or the multiplexer 530 can alternately select one of the buffer signals BS3 and BS4 to generate the drive signal DRV2, where there is a phase difference between the drive signal DRV1 and the drive signal DRV2.

[0046] Please refer to Figure 6 , which shows a schematic diagram of a touch sensing device according to an embodiment of the present disclosure. The touch sensing device 600 can be applied to a touch display device. The touch sensing device 600 includes a touch detection circuit and a touch sensing array 630. The touch sensing array 630 can be overlapped and configured on the display panel of the touch display device. The display panel can be a liquid crystal display (LCD) panel, a light emitting diode (LED) display panel, or an organic LED (OLED) display panel. The touch detection circuit includes a plurality of drive signal generators 611 - 61N and a plurality of sense signal receivers 621 - 62M. In some embodiments, the touch detection circuit can be integrated with the display driver of the display panel to form a touch and display driver (TDDI) circuit.

[0047] The touch sensing array 630 includes a plurality of touch sensing plates TP, and the touch sensing plates TP are arranged in an array. Each of the drive signal generators 611 - 61N corresponds to each row of the touch sensing array 630, and each of the sense signal receivers 621 - 62M corresponds to each column of the touch sensing array 630. Each of the drive signal generators 611 - 61N generates a drive signal to the corresponding touch sensing plate TP, and the sense signal receivers 621 - 62M respectively receive a plurality of sense signals generated by the corresponding touch sensing plate based on the drive signal during the sensing period.

[0048] In this embodiment, the touch sensing plate TP is a capacitive touch sensing plate.

[0049] Please refer to Figure 7 , which shows a waveform diagram of the drive signal of the touch sensing device according to an embodiment of the present disclosure. In this embodiment, the drive signal generators can be grouped into a plurality of signal generator groups, each signal generator group can include 4 drive signal generators, and the 4 drive signal generators can respectively generate drive signals DRV1 to DRV4. In Figure 7Among them, one of the drive signals DRV1 to DRV4 can have a first phase during each of the multiple touch sensing cycles STP1 - STP4, while the other drive signals DRV1 to DRV4 can have a second phase, where the first phase is different from the second phase. Specifically, during the touch sensing cycle STP1, the drive signal DRV1 has a negative phase, and the drive signals DRV2 - DRV4 have a positive phase; during the touch sensing cycle STP2, the drive signal DRV2 has a negative phase, and the drive signals DRV1, DRV3, and DRV4 have a positive phase; during the touch sensing cycle STP3, the drive signal DRV3 has a negative phase, and the drive signals DRV1, DRV2, and DRV4 have a positive phase; during the touch sensing cycle STP4, the drive signal DRV4 has a negative phase, and the drive signals DRV1 - DRV3 have a positive phase.

[0050] Please refer jointly to Figure 7 and Figure 8 , where Figure 8 shows a schematic diagram of a touch sensing operation according to an embodiment of the present disclosure. In Figure 8 , during the touch sensing cycle STP1, the drive signals DRV1 - DRV4 with phases -, +, +, + can be transmitted to the touch sensing panels TP1 - TP4. The sensing signal receiver RX1 corresponding to the touch sensing panels TP1 - TP4 can receive the sensing signal w from the touch sensing panels TP1 - TP4 during the touch sensing cycle STP1. During the touch sensing cycle STP2, the drive signals DRV1 - DRV4 with phases +, -, +, + can be transmitted to the touch sensing panels TP1 - TP4. The sensing signal receiver RX1 can receive the sensing signal x from the touch sensing panels TP1 - TP4 during the touch sensing cycle STP2. During the touch sensing cycle STP3, the drive signals DRV1 - DRV4 with phases +, +, -, + can be transmitted to the touch sensing panels TP1 - TP4. The sensing signal receiver RX1 can receive the sensing signal y from the touch sensing panels TP1 - TP4 during the touch sensing cycle STP3. In addition, during the touch sensing cycle STP4, the drive signals DRV1 - DRV4 with phases +, +, +, - can be transmitted to the touch sensing panels TP1 - TP4. The sensing signal receiver RX1 can receive the sensing signal z from the touch sensing panels TP1 - TP4 during the touch sensing cycle STP4. In this embodiment, the sensing signals w, x, y, z can be generated according to the capacitance change values a, b, c, d of the corresponding drive signals DRV1 to DRV4 and the touch sensing panels TP1 - TP4, respectively.

[0051] The relationship between the sensing signals w, x, y, z and the capacitance change values a, b, c, d can be expressed by the following formula:

[0052]

[0053] By expanding the above matrix operations, the following system of equations can be obtained:

[0054]

[0055] Here, through the system of equations shown above, the capacitance change values a, b, c, and d can be obtained, and touch information can be generated based on the capacitance change values a, b, c, and d.

[0056] Please note that in this embodiment, one of the drive signals DRV1 - DRV4 is selected to have a different phase (the first phase). In some other embodiments, two or more of the drive signals DRV1 - DRV4 can be selected to have the first phase. In addition, one signal generator group can have two or more drive signal generators. The four drive signal generators in one signal generator group in this embodiment are only illustrative examples and do not limit the scope of the invention of the present disclosure.

[0057] In summary, the present disclosure provides a drive signal generator to generate a drive signal that swings between a positive voltage and a negative voltage for touch sensing detection operations. This can reduce the swing amplitude of the drive signal and reduce the interference of low - frequency noise, while also enhancing the performance of touch sensing operations.

[0058] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A touch detection circuit, comprising: At least one drive signal generator, receiving a first power supply voltage and a second power supply voltage as operating power supplies, wherein each of the at least one drive signal generators generates at least one drive signal based on the first power supply voltage and the second power supply voltage, and each of the at least one drive signals swings between a first voltage and a second voltage, wherein the first voltage is a positive voltage and the second voltage is a negative voltage.

2. The touch detection circuit according to claim 1, wherein the first power supply voltage is a positive voltage and the second power supply voltage is a negative voltage.

3. The touch detection circuit according to claim 1, wherein the absolute value of the first power supply voltage is greater than the absolute value of the first voltage, and the absolute value of the second power supply voltage is greater than the absolute value of the second voltage.

4. The touch detection circuit according to claim 1, wherein the first voltage is the first power supply voltage multiplied by N, and the second voltage is the second power supply voltage multiplied by M, wherein N and M are positive real numbers less than 1, and N and M are the same or different.

5. The touch detection circuit according to claim 1, wherein each of the drive signal generators comprises: A first voltage buffer, receiving the first power supply voltage as an operating power supply and generating the first voltage based on the first input voltage according to the first power supply voltage; A second voltage buffer, receiving the second power supply voltage as an operating power supply and generating the second voltage based on the second input voltage according to the second power supply voltage; A signal conversion circuit, coupled to the first voltage buffer and the second voltage buffer, receiving the first voltage and the second voltage as power supply voltages, and generating a conversion signal by converting an input code; And A third voltage buffer, receiving the conversion signal and generating the drive signal according to the conversion signal.

6. The touch detection circuit according to claim 5, wherein each of the first voltage buffer, the second voltage buffer, and the third voltage buffer is a voltage follower.

7. The touch detection circuit according to claim 5, wherein the signal conversion circuit is a digital-to-analog conversion circuit, the input code is a digital code, and the conversion signal is an analog signal.

8. The touch detection circuit according to claim 1, wherein each of the drive signal generators comprises: A first signal conversion circuit, generating a first conversion signal according to a first input code; A second signal conversion circuit, generating a second conversion signal according to a second input code; A first voltage buffer, coupled to the first signal conversion circuit and generating a first buffer signal according to the first conversion signal; A second voltage buffer, coupled to the second signal conversion circuit and generating a second buffer signal according to the second conversion signal; And A multiplexer, coupled to the first voltage buffer and the second voltage buffer, and generating the drive signal by alternately selecting the first buffer signal and the second buffer signal.

9. The touch detection circuit according to claim 8, wherein each of the first voltage buffer and the second voltage buffer is a voltage follower.

10. The touch detection circuit according to claim 8, wherein each of the first signal conversion circuit and the second signal conversion circuit is a digital-to-analog signal converter.

11. The touch detection circuit according to claim 8, wherein each of the drive signal generators further comprises: a third signal conversion circuit configured to generate a third conversion signal according to a third input code; a fourth signal conversion circuit configured to generate a fourth conversion signal according to a fourth input code; a third voltage buffer coupled to the third signal conversion circuit and configured to generate a third buffer signal according to the third conversion signal; and a fourth voltage buffer coupled to the fourth signal conversion circuit and configured to generate a fourth buffer signal according to the fourth conversion signal, wherein the multiplexer further generates the drive signal having a first phase by alternately selecting the first buffer signal and the second buffer signal, or generates the drive signal having a second phase by alternately selecting the third buffer signal and the fourth buffer signal, wherein the first phase is different from the second phase.

12. The touch detection circuit according to claim 1, wherein there is a first phase difference between the first buffer signal and the third buffer signal, a second phase difference between the second buffer signal and the fourth buffer signal, and the first phase difference is equal to the second phase difference.

13. The touch detection circuit according to claim 1, wherein when the number of the at least one drive signal generator is greater than 1, the plurality of drive signal generators are grouped into N drive signal generator groups, wherein each of the N drive signal generator groups provides a plurality of drive signals, and at least one of the drive signals is set to the first phase while the other drive signals are set to the second phase, where N is a positive integer and the first phase is different from the second phase.

14. The touch detection circuit according to claim 3, wherein during each of the plurality of sensing periods, the phase of each of the drive signals is set to the first phase.

15. The touch detection circuit according to claim 4, further comprising: at least one sense signal receiver configured to receive a plurality of sense signals generated by a plurality of touch sensor panels based on the drive signals during the plurality of touch sensing periods.

16. The touch detection circuit according to claim 5, wherein the at least one sense signal receiver performs operations on the drive signals of the plurality of touch sensing periods to obtain touch information.

17. The touch detection circuit according to claim 1, wherein the touch detection circuit is applied to a touch display device, and the touch display device has a display panel, wherein the display panel is a liquid crystal display panel, a light emitting diode display panel, or an organic light emitting diode display panel.

18. The touch detection circuit according to claim 1, wherein the touch detection circuit is included in a touch display driver circuit.

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