TWI825761B - Capacitive touch sensor - Google Patents

Abstract

A capacitive touch sensor includes a touch interface, a switch, and a sensing circuit. The switch circuit switches based on sensing conditions of self-capacitance and mutual capacitance. The sensing circuit is used for both the self-capacitance mode and the self-capacitance mode to simplify circuit structure and save circuit area and power consumption. The output sensing voltage from the sensing circuit is stable. A differential mode is designed to improve noise interference and enhance accuracy of judging the touch effect. Then, the self-capacitance mode is utilized for the areas of possible touches to save operation time for the capacitance mode.

Description

Capacitive touch sensor

The present invention relates to a touch sensor, and in particular to a capacitive touch sensor that can switch between self-capacitance, mutual capacitance and differential modes.

Capacitive touch sensors are an input tool for human-computer interfaces. Generally speaking, capacitive touch sensors are divided into self capacitance and mutual capacitance. The so-called self-capacitance means that the driving electrode and the sensing electrode are both at the same point, and the change in the equivalent capacitance value of the electrode is detected to determine the touch effect; while the mutual capacitance means that the driving electrode and the sensing electrode are two separate points, and the detection The change in equivalent capacitance value between the driving electrode and the sensing electrode is used to determine the touch effect. Self-capacitance and mutual capacitance each have their own advantages and disadvantages. When the touch panel is divided into M*N touch channels, self-capacitance only needs M+N scans to complete, while mutual capacitance requires M*N scans. It will take a long time for the scan to complete. However, self-containment has the problem of ghost points. It will cause misjudgment during multi-touch, but not mutual tolerance, so multi-touch can be achieved.

Taiwan Patent No. I630523 discloses a touch device, its sensing method and touch sensing circuit. Compared with the conventional technology, different sensing modes require different sensing circuits. This patent discloses that by switching the switch circuit, the same sensing circuit can be used to achieve self-capacitance and mutual capacitance multi-mode sensing, simplifying the circuit. structure. However, its disadvantage is that it requires a specially designed touch panel. When the touch panel is divided into M*N touch channels, M*N touch channels are required. The traces are connected to the switch circuit and the sensing circuit, and a commonly used touch panel only needs M+N traces to connect to the sensing circuit, so the complex panel traces greatly reduce the practicality.

Taiwan Patent No. I489365 discloses a capacitive touch sensor and its self-capacitance and mutual capacitance switching method. The driving unit and the sensing unit are integrated through the switching of an analog multiplexer. Simplify the circuit structure. This architecture can be used with a commonly used touch panel and only requires M+N wires to be connected to the sensing circuit. However, its disadvantage is that the self-capacitance mode and mutual capacitance mode require a voltage source and a current source respectively, which increases power consumption. Moreover, due to the operation method of this architecture, the output sensing voltage will jitter, which will affect the accuracy of judging the touch effect.

Chinese Patent No. CN103197787 discloses a capacitive touch sensor that combines the sensing values of self-capacitance and mutual capacitance to eliminate noise. However, its disadvantage is that it requires more time to perform self-capacitance mode and mutual capacitance mode. Long scanning time will reduce the response speed of touch effects on large-size panels with a large number of channels.

Chinese Patent No. CN103257760 discloses a time-saving scanning method for capacitive touch sensors. The concept is to first perform a first-stage estimation scan, and then perform a second-stage precision scan on areas where touch points may occur. Scan. The above method only covers the concept of mutual capacitance scanning. If judged based on the scanning results of self-capacity mode, the scanning time can be further optimized.

Based on the above problems, the present invention discloses a capacitive touch sensor that switches between self-capacitance and mutual capacitance. Compared with the above-mentioned previous case, the sensing circuit of the present invention can realize self-capacitance and mutual capacitance when used with a commonly used touch panel. Capacitive sensing does not require an additional current source, saving circuit area and power consumption. The differential mode is designed to improve noise interference and improve the accuracy of judging the touch effect. And it combines the scanning results of self-capacitance mode and mutual capacitance mode to make judgments, saving scanning time and improving response speed.

The invention discloses a capacitive touch sensor, which includes a touch interface with a plurality of first lines and a plurality of second lines; a first switch circuit connected between the first lines and a mutual capacitance voltage. time; a second switch circuit that receives the first lines and the second lines and a self-capacitance voltage to generate a sensing input voltage; and a sensing circuit that receives the sensing input voltage and generates a sensing input voltage. Measure the output voltage.

The above-mentioned capacitive touch sensor, wherein the first switch circuit includes at least one first switch unit; the first switch unit(s) are connected between the first line and the mutual capacitance voltage; a first sensor A detection switch is connected between the touch interface and the output terminal of the switch unit(s); and a second sensing switch is connected between the output terminal of the switch circuit(s) and the adjacent switch unit(s). .

The above-mentioned capacitive touch sensor, wherein the second switch circuit includes at least one second switch unit; the second switch unit(s) includes: a self-capacitance voltage switch connected to the self-capacitance voltage and the touch between the interfaces; a first sensing switch connected between the touch interface and the output end of the switch unit(s); and a second sensing switch connected between the output end of the switch circuit(s) and between adjacent switch units.

In the above capacitive touch sensor, the second switch unit further includes a second self-capacitance switch connected between a second self-capacitance voltage and the touch interface.

In the above-mentioned capacitive touch sensor, the operation mode of the first switch circuit and the second switch circuit includes: a mutual capacitance mode, in which the first switch units are sequentially turned on in the first switch circuit to provide the Mutual capacitance voltage to the first lines; the first sensing switch is turned on in the second switch units, and the self-capacitance voltage switch, the second sensing switch and the second self-capacitance switch are turned off; and a self-capacitance switch mode, turn off the first switch units, and turn on the first switch units according to the scan channel Sensing the switch or the second sensing switch, and turning on the self-capacitance voltage switch or the second self-capacitance switch according to the operation timing of the sensing circuit.

In the above-mentioned capacitive touch sensor, the operation mode of the self-capacitance mode includes: an odd-numbered mode, in the odd-numbered second switch units, the first sensing switch and the second sensing switch are both is turned on, and the self-capacitance voltage switch is turned on according to the operation sequence of the sensing circuit, and the second self-capacitance switch is turned off; in the even-numbered second switch units, the first sensing switch and the second sensing The switches are all turned off, and the second self-capacitance switch is turned on according to the operation sequence of the sensing circuit, and the self-capacitance voltage switch is turned off; and an even mode, in which the first sensing unit is ordered in an even number among the second switching units. The switch and the second sensing switch are both turned on, and the second self-capacitance switch is turned on according to the operation timing of the sensing circuit, and the self-capacitance voltage switch is turned off; among the odd-numbered second switch units, the first The sensing switch and the second sensing switch are both closed, and the self-capacitance voltage switch is turned on according to the operation timing of the sensing circuit, and the second self-capacitance switch is turned off.

In the above-mentioned capacitive touch sensor, the sensing circuit includes one or a plurality of sensing units; if it only includes one sensing unit, whether in mutual capacitance mode or self-capacitance mode, the second sensing circuit must be turned on in sequence. The first sensing switch or the second sensing switch in the switch unit sequentially obtains the sensing output voltage of each first line or second line; if a plurality of sensing units are included, the second sensing switches can be The output end of the switch unit is connected to the sensing units respectively, and the first sensing switch or the second sensing switch is turned on at the same time, and the sensing output voltages of the sensing units are obtained at the same time.

The above-mentioned capacitive touch sensor, wherein the sensing unit includes: a first amplifier, the positive input terminal of the first amplifier is connected to a reference voltage, and the negative input terminal of the first amplifier is connected to the output terminal of the switch circuit , the negative input terminal of the first amplifier and the output terminal of the first amplifier are connected to a first capacitor and a first timing switch; a second amplifier, the positive input terminal of the second amplifier is connected to the reference voltage, the second amplifier A first resistor is connected between the negative input terminal and the output terminal of the first amplifier to and a second timing switch, the second amplifier input negative terminal and the second amplifier output terminal are connected to a second capacitor and a third timing switch; wherein the second amplifier output terminal is the sensing output voltage.

The above-mentioned capacitive touch sensor, wherein the sensing unit further includes a third amplifier, the positive input terminal of the third amplifier is connected to the reference voltage, and the negative input terminal of the third amplifier is connected to the first resistor. A second timing negative terminal switch is connected, the negative input terminal of the third amplifier and the output terminal of the third amplifier are connected to a second negative terminal capacitor and a third timing negative terminal switch, wherein the output terminal of the third amplifier is the inductor. Measure negative output voltage.

The above-mentioned capacitive touch sensor includes: a first sequence that turns on the first sequence switch of the sensing unit. If it is a self-capacitive mode, it also turns on the self-capacitance switch in the second switch units. voltage capacitance switch; a second timing sequence, turning on the second timing switch or the second timing negative end switch of the sensing unit; and a third timing sequence, turning on the third timing switch or the third timing switch of the sensing unit Sequential negative switch.

The above-mentioned capacitive touch sensor, wherein the sensing unit is connected to a switching circuit to receive at least two of the sensing output voltage, the sensing output voltage of the adjacent sensing unit, and the reference voltage. , outputting a switching circuit positive output voltage and a switching circuit negative output voltage, and including at least one of the following switching modes: a first switching mode, selecting the sensing output voltage of the sensing unit and the adjacent sensing The sensing output voltage of the unit is used as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit; and a second switching mode selects the sensing output voltage of the sensing unit and the reference voltage as the The switching circuit positive output voltage and the switching circuit negative output voltage.

The above-mentioned capacitive touch sensor, wherein the sensing unit further includes a sensing negative output voltage, and is connected to a switching circuit to receive the sensing output voltage, the sensing negative output voltage, and the adjacent sensing unit The sensing output voltage, the sensing negative output voltage of the adjacent sensing unit, and the reference voltage At least two voltages in the voltage output a switching circuit positive output voltage and a switching circuit negative output voltage, and include at least one of the following switching modes: a first switching mode, selecting the sensing output of the sensing unit The voltage and the sensing output voltage of the adjacent sensing unit are used as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit; a second switching mode selects the sensing output voltage of the sensing unit and the The reference voltage serves as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit; a third switching mode selects the sensing negative output voltage of the sensing unit and the sensing negative output of the adjacent sensing unit voltage, as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit; and a fourth switching mode, selecting the sensing negative output voltage of the sensing unit and the reference voltage as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit.

The above-mentioned capacitive touch sensor further includes an analog-to-digital converter that receives the sensing output voltages, the sensing negative output voltages, the switching circuit positive output voltages, or the switching circuit negative output voltages. , output a digital signal.

In the above-mentioned capacitive touch sensor, the first lines or the second lines in the touch interface are respectively connected to a reference capacitive switch, and the other end of the reference capacitive switch is connected to a reference capacitor. The capacitor is connected to a mutual capacitance second voltage; the reference capacitance switches can be turned on in the mutual capacitance mode and turned off in the self-capacitance mode.

The operation method of the above-mentioned capacitive touch sensor includes: first executing the self-capacitance mode, and determining the lines in the first lines whose self-capacitance sensing values exceed a preset range; and then executing the mutual capacitance mode. , only the lines whose self-capacitance sensing values exceed the preset range among the first lines are scanned for mutual capacitance, and the other lines among the first lines whose self-capacitance sensing values do not exceed the preset range are not scanned for mutual capacitance. scan.

In the above-mentioned operation method, the mutual capacitance mode scan will not be performed on the areas that the self-capacitance sensing thinks have not been touched. Compared with the previous method where each channel still needs to be scanned in the mutual capacitance mode, the scanning time is saved.

In order to further understand the characteristics and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, these descriptions and attached drawings are only used to illustrate the present invention, but not to obtain rights to the present invention. Any limitations on the scope shall be imposed.

10:Touch interface

101: First line (TX)

102: Second line (RX)

C _M : Mutual capacitance sensing capacitance

C _S : Self-capacitance sensing capacitance

20: First switch circuit

201: First switch unit

202: First switch unit

30: Second switch circuit

310: Second switch unit

320: Second switch unit

301:Self-capacitance voltage switch

302: First sensing switch

303: Second sensing switch

304: Second self-capacitance switch

40: Sensing circuit

410: Sensing unit

420: Sensing unit

401: First amplifier

402: First capacitor

403: First timing switch

404: Second amplifier

405: First resistor

406: Second timing switch

407: Second capacitor

408: The third timing switch

409:Third amplifier

406N: Second timing negative switch

407N: Second negative terminal capacitor

408N: Third timing negative terminal switch

50:Analog-to-digital converter

60:Switching circuit

70: Reference capacitive switch

C70: Reference capacitor

V01: Mutual capacitance voltage

V02: Self-capacitance voltage

V021: Second self-capacitance voltage

V03: Sensing input voltage

V04: Sensing output voltage

V05: reference voltage

V06: Switching circuit positive output voltage

V06N: Switching circuit negative output voltage

V07: Mutual capacitance second voltage

Figure 1 illustrates the structure of a capacitive touch sensor according to a first embodiment of the present invention.

Figure 2 shows the structure of the first switch circuit in Figure 1 .

Figure 3 shows the structure of the second switch circuit in Figure 1 . .

Figure 4 shows another aspect of the second switch circuit in Figure 3.

Figure 5 shows the structure of the sensing circuit in Figure 1.

Figure 6 shows the structure of the sensing unit of Figure 5.

Figure 7 illustrates another aspect of the sensing unit of Figure 6 .

Figure 8 illustrates the complete circuit of the capacitive touch sensor according to the first embodiment of the present invention.

Figure 9 illustrates the circuit of a capacitive touch sensor according to the second embodiment of the present invention.

Figure 10 illustrates the circuit of a capacitive touch sensor according to the third embodiment of the present invention.

FIG. 11 illustrates an example of the operation timing of the capacitive touch sensor of the present invention.

The present invention will be described more specifically with reference to the following examples. Please note that the following description of the embodiments of the present invention is for illustrative purposes only; it is not meant to be an exhaustive description of the present invention or to limit the invention to the form disclosed.

Please refer to Figure 1 of the first embodiment of the present invention, which illustrates the structure of a capacitive touch sensor, including a touch interface 10 with a plurality of first lines (TX) 101 and a plurality of second lines (TX). RX) 102; a first switch circuit 20, connected between the first line (TX) 101 and a mutual capacitance voltage V01; a second switch circuit 30, receiving the first lines (TX) 101 and the The second line (RX) 102 and a self-capacitance voltage V02 generate a sensing input voltage V03; a sensing circuit 40 receives the sensing input voltage V03 and generates a sensing output voltage V04; an analog-to-digital converter 50. Receive the sensing output voltage V04 and generate a digital output signal.

Figure 2 illustrates the circuit structure of the first switch circuit 20. The first switch circuit 20 includes a plurality of first switch units 201, 202, where each first switch unit 201, 202 is connected between the first line (TX) 101 and the mutual capacitance voltage V01. The mutual capacitance voltage V01 is usually a square wave signal.

Figure 3 illustrates the circuit structure of the second switch circuit 30. In the figure, C _M represents the inductive capacitance between the first lines (TX) 101 and the second lines (RX) 102 in the mutual capacitance mode, and _CS represents the first lines (TX) 101 in the self-capacitance mode. Or the inductive capacitance of the second lines (RX) 102. The second switch circuit 30 includes a plurality of second switch units 310, 320, where each second switch unit 310, 320 includes a self-capacitance voltage switch 301 connected to the self-capacitance voltage V02 and the first lines (TX) 101 or the between the second lines (RX) 102; a first sensing switch 302, connected between the first lines (TX) 101 or the second lines (RX) 102 and the sensing input voltage V03; A second sensing switch 303 is connected between the sensing input voltage V03 and the adjacent second switch unit 320. The self-capacitance voltage V02 is usually a fixed voltage DC signal.

FIG. 4 illustrates another circuit structure of the second switch circuit 30 . Compared with Figure 3, the second switch units 310, 320 further include a second self-capacitance voltage V021 and a second self-capacitance switch 304. The second self-capacitance switch 304 is connected to the second self-capacitance voltage V021 and the second self-capacitance switch 304. between the first lines (TX) 101 or the second lines (RX) 102. The second self-capacitance voltage V021 is usually a fixed voltage DC signal.

In the above-mentioned capacitive touch sensor, the operation mode of the first switch circuit 20 and the second switch circuit 30 includes: a mutual capacitance mode, sequentially turning on the first switch units 201, 202 to provide the mutual capacitance voltage. V01 to the first lines (TX) 101, each second switch unit 310, 320 turns on the first sensing switch 302, turns off the self-capacitance voltage switch 301, the second sensing switch 303 and the second self-capacitance switch 304; and a self-capacitance mode, turning off the first switch circuit 20, each second switch unit 310, 320 turning on the first sensing switch 302 or the second sensing switch 303 according to the scan channel, and according to the sensing circuit 40 The operation sequence turns on the self-capacitance voltage switch 301 or the second self-capacitance switch 304 .

In the above-mentioned capacitive touch sensor, in the self-capacitance mode, the operation modes of the second switch units 310 and 320 include: an odd mode, in which the first sensing switches 302 of the second switch units 310 are sorted into odd numbers. And the second sensing switch 303 is all turned on, and the self-capacitance voltage switch 301 is turned on according to the operation timing of the sensing circuit 40, and the second self-capacitance switch 304 is turned off; the second switching unit 320 of the even number is The first sensing switch 302 and the second sensing switch 303 are both closed, and the second self-capacitance switch 304 is turned on according to the operation timing of the sensing circuit 40, and the self-capacitance voltage switch 301 is turned off. In an even mode, the first sensing switch 302 and the second sensing switch 303 of the second switching unit 310 in an odd number are both turned off, and the second self-capacitance switch is turned on according to the operation timing of the sensing circuit 40 304. Turn off the self-capacitance voltage switch 301; the first sensing switch 302 and the second sensing switch 303 of the second switching unit 320 in an even number are both turned on, and according to the operation timing of the sensing circuit 40 The self-capacitance voltage switch 301 is turned on and the second self-capacitance switch 304 is turned off. If there are more second switch units, the rest can be deduced by analogy.

FIG. 5 illustrates the structure of the sensing circuit 40 including a plurality of sensing units 410, 420. If there is only one set of sensing units 410, whether in mutual capacitance mode or self-capacitance mode, the first sensing switch 302 or the second sensing switch 303 in the second switching units 310, 320 needs to be turned on in sequence. Get the sensing output voltage V04 of each channel. If there are a plurality of sensing units 410, 420, the output terminals V03 and V03-1 of the second switch units 310, 320 can be connected to the sensing units 410, 420 respectively, and at the same time, the first sensing switches 302 or the third sensing switches 302 can be turned on. The two sensing switches 303 obtain the sensing output voltages V04 and V04-1 of multiple channels at the same time. In addition, a plurality of analog-to-digital converters 50 may also be included to simultaneously convert the sensing output voltages V04 and V04-1 of these channels into digital output signals respectively.

Figure 6 illustrates the architecture of the sensing units 410, 420. The sensing unit 410 includes: a first amplifier 401. The positive input terminal of the first amplifier 401 is connected to a reference voltage V05. The negative input terminal of the first amplifier 401 is connected to the sensing input voltage V03. A first capacitor 402 and a first timing switch 403 are connected between the negative input terminal and the output terminal of an amplifier 401; and a second amplifier 404, the positive input terminal of the second amplifier 404 is connected to the reference voltage V05, A first resistor 405 and a second timing switch 406 are connected between the negative input terminal of the second amplifier 404 and the output terminal of the first amplifier 401. The negative input terminal of the second amplifier 404 is connected to the output terminal. A second capacitor 407 and a third timing switch 408; the output terminal of the second amplifier 404 is the sensing output voltage V04.

Figure 7 illustrates another structure of the sensing unit 410. Compared with Figure 6, the sensing unit 410 further includes a third amplifier 409. The input positive terminal of the third amplifier 409 is connected to the reference voltage V05, and the input negative terminal of the third amplifier 409 is connected to the first resistor. A second timing negative terminal switch 406N is connected between the amplifier 405 and a second negative terminal capacitor 407N is connected between the input negative terminal and the output terminal of the third amplifier 409 And a third timing negative terminal switch 408N, wherein the output terminal of the third amplifier 409 is the sensing negative output voltage V04N.

The operation sequence of the above-mentioned capacitive touch sensor includes: a first sequence, turning on the first sequence switch 403 of the sensing units 410, 420, and if it is in the self-capacitance mode, also turning on the second switches The self-capacitance voltage switch 301 in the unit 310; a second timing, turns on the second timing switch 406, if a second timing negative terminal switch 406N is included, turns on the second timing switch 406 and the second timing negative switch respectively. terminal switch 406N; and a third timing to turn on the third timing switches 408. If a third timing negative terminal switch 408N is included, the third timing switch 408 and the third timing negative terminal switch 408N are turned on respectively.

Figure 8 shows the complete circuit of the first embodiment of the present invention. The second switch circuit 30 adopts the structure of FIG. 4 , and the sensing circuit 40 only includes one sensing unit 410 and adopts the structure of FIG. 6 . The analog-to-digital converter 50 receives the sensing output voltage V04 and converts it into a digital output signal.

Figure 9 shows the circuit of the second embodiment of the present invention. The second switch circuit 30 adopts the structure of Figure 4, and the sensing circuit 40 includes a plurality of sensing units 410, 420,..., and adopts the structure of Figure 6. If the touch interface 10 includes 50 first lines (TX) 101 and 30 second lines (RX) 102, then the second switch circuit 30 includes 30 groups of second switch units 310, 320,..., the sensing The circuit 40 includes 30 groups of sensing units 410, 420, .... In the mutual capacitance mode, the corresponding first switch units 201 are turned on in turn for the 50 first lines (TX) 101, and the 30 groups of sensing units 410, 420 can be activated simultaneously. ,..., detect the capacitance value of the mutual capacitance sensing capacitance C _M of the 30 second lines (RX) 102. The self-capacitance mode needs to be divided into an odd number mode and an even number mode in order to detect the capacitance value of the self-capacitance sensing capacitor _CS of the 30 second lines (RX) 102. In addition, the 50 first lines (TX) 101 can also be connected to the second switch circuit 30 and the sensing circuit 40 to detect the capacitance value of the self-capacitance sensing capacitor _CS of the 50 first lines (TX) 101. .

The capacitive touch sensor in Figure 9, in which the sensing units 410 and 420 are respectively connected to a switching circuit 60 to receive the sensing output voltage V04, and the sensing output voltage V04-1 of the adjacent sensing unit 420 , and the reference voltage V05, outputs a switching circuit positive output voltage V06 and a switching circuit negative output voltage V06N; and includes the following two switching modes: a first switching mode, selecting the sensing output voltage V04 and the adjacent sensing unit The sensing output voltage V04-1 of 420 is used as the switching circuit positive output voltage V06 and the switching circuit negative output voltage V06N; and a second switching mode selects the sensing output voltage V04 and the reference voltage V05 as The switching circuit has a positive output voltage V06 and a switching circuit has a negative output voltage V06N.

The capacitive touch sensor in Figure 9, in which the switching circuit 60 selects the second switching mode in the self-capacitance mode, can detect the capacitance value of the self-capacitance sensing capacitor C _S of the second line (RX) 102 ;Selecting the second switching mode in the mutual capacitance mode can detect the capacitance value of the mutual capacitance sensing capacitor C _M of the second line (RX) 102; selecting the first switching mode in the mutual capacitance mode can detect The difference in capacitance value of the mutual inductive capacitance C _M between two adjacent second lines (RX) 102 in the second line (RX) 102 (CM _-2 - _{C M-1} ).

Figure 10 shows a circuit of the third embodiment of the present invention, in which the second switch circuit 30 adopts the structure of Figure 4, and the sensing circuit 40 includes a plurality of sensing units 410, 420,..., which adopts the structure of Figure 7 The architecture also includes a sensing negative output voltage V04N, V04-1N,... The switching circuit 60 receives the sensing output voltage V04, the sensing negative output voltage V04N, the sensing output voltage V04-1 of the adjacent sensing unit 420, and the sensing output voltage V04-1 of the adjacent sensing unit 420. The negative output voltage V04-1N, and at least two voltages in the reference voltage V05, output a switching circuit positive output voltage V06 and a switching circuit negative output voltage V06N, and the switching circuit positive output voltage V06 and the switching circuit negative output The voltage V06N includes the following switching modes: a first switching mode, which selects the sensing output voltage V04 and the adjacent sensing output voltage V04-1; a second switching mode, which selects the sensing output voltage V04 and the reference voltage V05; The third switching mode selects the sensing negative output voltage V04N and the adjacent Sense the negative output voltage V04-1N; a fourth switching mode, select to sense the negative output voltage V04N and the reference voltage V05.

The capacitive touch sensor in Figure 10, in which the switching circuit 60 selects the second switching mode or the fourth switching mode in the self-capacitance mode, can detect the self-capacitance sensing of the second line (RX) 102 The capacitance value of the capacitor C _S ; by selecting the second switching mode or the fourth switching mode in the mutual capacitance mode, the capacitance value of the mutual capacitance sensing capacitance C _M of the second line (RX) 102 can be detected; in the mutual capacitance mode By selecting the first switching mode or the third switching mode in the mode, the capacitance value difference ( _{CM -2} -CM _-1 ).

The capacitive touch sensor in Figure 8, Figure 9 or Figure 10 further includes an analog-to-digital converter 50 that receives the sensing output voltage V04, the sensing negative output voltage V04N, and the switching circuit positive The output voltage V06 or the negative output voltage V06N of the switching circuit outputs a digital signal.

The capacitive touch sensor in Figure 10, in which the second lines (RX) 102 in the touch interface 10 are respectively connected to a reference capacitive switch 70, and the other end of the reference capacitive switch 70 is connected to a reference capacitor. C70, the reference capacitor C70 is connected to a mutual capacitance second voltage V07; the reference capacitance switch 70 can be turned on in the mutual capacitance mode, and can be turned off in the self-capacitance mode. The embodiments of FIGS. 1 , 8 and 9 may also include the reference capacitance switch 70 , the reference capacitor C70 and the mutual capacitance second voltage V07 . Its function is to deduct a reference value when sensing the capacitance value of the mutual capacitance sensing capacitor C _M to improve the uniformity of the sensing results.

Figure 11 illustrates an example operation timing diagram of the capacitive touch sensor of the present invention, in which the mutual capacitance voltage V01 and the second mutual capacitance voltage V07 are both square wave signals, and the first switch circuit 20 and the third The two switch circuits 30 switch according to the aforementioned mutual capacitance mode. The reference voltage V05 is set to half of the power supply voltage (VDD/2). The switching circuit 60 can select the switching mode according to the potential of the mutual capacitance voltage V01. When the potential is high, The second switching mode is selected, and the fourth switching mode is selected when the potential is low, and the first timing, the second timing, and the third timing are sequentially entered, using the principle of charge transfer, the mutual capacitance sensing capacitance C The capacitance value of _M is converted into the sensing output voltage V04, and finally converted into a digital signal through the analog-to-digital converter 50.

The operation sequence of the self-capacitance mode of the capacitive touch sensor of the present invention can also be referred to Figure 11. The first switch circuit 20 and the second switch circuit 30 switch according to the aforementioned self-capacitance mode. The self-capacitance voltage V02 is set to the power supply voltage (VDD), the second self-capacitance voltage V021 is set to 0V, the reference voltage V05 is set to half of the power supply voltage (VDD/2), the switching circuit 60 can also be based on the potential of the mutual capacitance voltage V01 Select the switching mode, select the second switching mode when the potential is high, select the fourth switching mode when the potential is low, and enter the first timing, the second timing and the third timing sequentially, using the principle of charge transfer , convert the capacitance value of the self-capacitance sensing capacitor _CS into the sensing output voltage V04, and finally convert it into a digital signal through the analog-to-digital converter 50.

The operation method of the above-mentioned capacitive touch sensor includes: first executing the self-capacitance mode, and determining the lines in the first lines (TX) 101 whose self-capacitance sensing values exceed a preset range; and then executing In this mutual capacitance mode, mutual capacitance scanning is only performed on the lines whose self-capacitance sensing values in the first lines (TX) 101 exceed the preset range, and the self-capacitance sensing values in the remaining first lines (TX) 101 are Lines that do not exceed the preset range will not be scanned for mutual capacitance, which can save operation time in mutual capacitance mode. If the touch interface 10 includes 50 first lines (TX) 101 and 30 second lines (RX) 102, the self-capacitance mode can be operated on the 50 first lines (TX) 101 first. If it is determined that among them The self-capacitance sensing values of the three first lines (TX) 101 exceed the preset range, which means that only these three first lines (TX) 101 may be touched by fingers. When operating the mutual capacitance mode next, only these three first lines (TX) 101 need to be touched. The first line (TX) 101 performs mutual capacitance scanning to determine the touch effect. The remaining 47 first lines (TX) 101 do not need to perform mutual capacitance scanning. The mutual capacitance mode originally requires sensing and processing 50x30=1500 mutual capacitances. feel According to the data, the above example only needs to sense and process 3x30=90 mutual capacitance sensing data, which can save the operation time of mutual capacitance mode and improve the reporting rate.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

101: First line (TX)

102: Second line (RX)

C _M : Mutual capacitance sensing capacitance

C _S : Self-capacitance sensing capacitance

201: First switch unit

30: Second switch circuit

310: Second switch unit

320: Second switch unit

301:Self-capacitance voltage switch

302: First sensing switch

303: Second sensing switch

304: Second self-capacitance switch

410: Sensing unit

401: First amplifier

402: First capacitor

403: First timing switch

404: Second amplifier

405: First resistor

406: Second timing switch

407: Second capacitor

408: The third timing switch

50:Analog-to-digital converter

V01: Mutual capacitance voltage

V02: Self-capacitance voltage

V021: Second self-capacitance voltage

V03: Sensing input voltage

V04: Sensing output voltage

V05: reference voltage

Claims (14)

A capacitive touch sensor includes: a touch interface having a plurality of first lines and a plurality of second lines; a first switch circuit connected between the first lines and a mutual capacitance voltage; a second switch circuit that receives the first lines and the second lines and a self-capacitance voltage to generate a sensing input voltage; and a sensing circuit that receives the sensing input voltage and generates a sensing output voltage, wherein the second switch circuit includes a plurality of second switch units; the second switch unit(s) include: a self-capacitance voltage switch connected between the self-capacitance voltage and the touch interface; a first sensor A detection switch is connected between the touch interface and the output end of the switch unit(s); and a second sensing switch is connected between the output end of the switch circuit(s) and the adjacent switch unit(s). . The capacitive touch sensor as described in item 1 of the patent application, wherein the first switch circuit includes at least one first switch unit; the first switch unit(s) are connected to the first line and the mutual capacitance between voltages. For the capacitive touch sensor described in item 2 of the patent application, the second switch unit further includes a second self-capacitance switch connected between a second self-capacitance voltage and the touch interface. The capacitive touch sensor described in Item 3 of the patent application is provided with: a mutual capacitance mode, in which the first switching units are sequentially turned on in the first switching circuit to provide the mutual capacitance voltage to the some first lines; the first sensing switch in the second switching units is turned on, and the self-capacitance voltage switch, the second sensing switch and the second self-capacitance switch are turned off; and A self-capacitance mode, turning off the first switch units, the second switch units turning on the first sensing switch or the second sensing switch according to the scan channel, and turning on the self-capacitance according to the operation timing of the sensing circuit The voltage switch or the second self-capacitance switch provides the self-capacitance voltage or the second self-capacitance voltage to the second lines or the first lines. For the capacitive touch sensor described in item 4 of the patent application, the self-capacitance mode includes: an odd number mode, in the second switch units arranged in an odd number, the first sensing switch and the third sensing switch Both sensing switches are turned on, and the self-capacitance voltage switch is turned on according to the operation timing of the sensing circuit, and the second self-capacitance switch is turned off; in the even-numbered second switch units, the first sensing switch and The second sensing switches are all turned off, and the second self-capacitance switch is turned on according to the operation timing of the sensing circuit, and the self-capacitance voltage switch is turned off; and an even mode is arranged in an even number of the second switch units, The first sensing switch and the second sensing switch are both turned on, and the self-capacitance voltage switch is turned on according to the operation timing of the sensing circuit, and the second self-capacitance switch is turned off; the second switch units are sorted into an odd number , the first sensing switch and the second sensing switch are both turned off, and the second self-capacitance switch is turned on according to the operation timing of the sensing circuit, and the self-capacitance voltage switch is turned off. For example, in the capacitive touch sensor described in item 4 of the patent application, the sensing circuit includes one or a plurality of sensing units; if it only includes one sensing unit, when performing scanning, the sensing circuit must be turned on in sequence. The first sensing switch or the second sensing switch in the second switch unit sequentially obtains the sensing output voltage of each first line or second line; if a plurality of sensing units are included, let the third sensing units The output terminals of the two switch units are respectively connected to the sensing units, and the first sensing switch or the second sensing switch is turned on at the same time, and the sensing output voltages of the sensing units are obtained at the same time. For the capacitive touch sensor described in Item 6 of the patent application, the sensing unit includes: a first amplifier, the positive input terminal of the first amplifier is connected to a reference voltage, and the negative input terminal of the first amplifier Connected to the output end of the switching circuit, the first amplifier negative input end and the first amplifier output end are connected to a first capacitor and a first timing switch; and a second amplifier, the second amplifier input positive end is connected to to the reference voltage, a first resistor and a second timing switch are connected between the negative input terminal of the second amplifier and the output terminal of the first amplifier, and a negative input terminal of the second amplifier is connected to the output terminal of the second amplifier. a second capacitor and a third timing switch; the output terminal of the second amplifier is the sensing output voltage. For the capacitive touch sensor described in item 7 of the patent application, the sensing unit further includes a third amplifier, the positive input terminal of the third amplifier is connected to the reference voltage, and the negative input terminal of the third amplifier A second timing negative terminal switch is connected to the first resistor, a second negative terminal capacitor and a third timing negative terminal switch are connected to the input negative terminal of the third amplifier and the output terminal of the third amplifier, wherein the third negative terminal switch The output of the three amplifiers is the sensed negative output voltage. For example, in the capacitive touch sensor described in item 8 of the patent application, the first timing switch of the sensing unit is turned on at a first timing sequence. If the self-capacitance mode is used, the first timing switch is also turned on. The self-capacitance voltage switch in the second switching unit; at a second timing, turn on the second timing switch or the second timing negative switch of the sensing unit; and at a third timing, turn on the sensing unit The third timing switch or the third timing negative terminal switch. For the capacitive touch sensor described in item 7 of the patent application, the sensing unit is connected to a switching circuit to receive the sensing output voltage, and the sensing output voltage of the adjacent sensing unit, And at least 2 voltages in the reference voltage output a switching circuit positive output voltage and a switching circuit negative output voltage, and are provided with: a first switching mode to select the sensing output voltage of the sensing unit and the phase The sensing output voltage of the adjacent sensing unit is used as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit respectively; and a second switching mode selects the sensing output voltage and the reference voltage of the sensing unit , respectively serve as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit. For the capacitive touch sensor described in item 8 of the patent application, the sensing unit has a sensing negative output voltage and is connected to a switching circuit to receive the sensing output voltage. The sensing negative output voltage , the sensing output voltage of the adjacent sensing unit, the sensing negative output voltage of the adjacent sensing unit, and at least 2 voltages of the reference voltage, output a switching circuit positive output voltage and a switching circuit Negative output voltage, and is provided with the following switching mode: a first switching mode, selecting the sensing output voltage of the sensing unit and the sensing output voltage of the adjacent sensing unit as the positive output of the switching circuit respectively voltage and the negative output voltage of the switching circuit; a second switching mode, selecting the sensing output voltage and the reference voltage of the sensing unit as the positive output voltage of the switching circuit and the negative output voltage of the switching circuit respectively; a first Three switching modes, selecting the sensing negative output voltage of the sensing unit and the sensing negative output voltage of the adjacent sensing unit as the switching circuit positive output voltage and the switching circuit negative output voltage respectively; and one In the fourth switching mode, the sensing negative output voltage and the reference voltage of the sensing unit are selected as the switching circuit positive output voltage and the switching circuit negative output voltage respectively. The capacitive touch sensor described in item 10 of the patent application further includes an analog-to-digital converter that receives the sensing output voltage, the sensing negative output voltage, the switching circuit positive output voltage, or the switching The circuit has a negative output voltage and outputs a digital signal. For the capacitive touch sensor described in item 4 of the patent application, the first lines or the second lines in the touch interface are respectively connected to a reference capacitive switch, and the other end of the reference capacitive switch Connected to a reference capacitor, the reference capacitor is connected to a mutual capacitance second voltage; the reference capacitance switch can be turned on in the mutual capacitance mode and turned off in the self-capacitance mode. For the capacitive touch sensor described in item 4 of the patent application, the self-capacitance mode is first executed, and the lines in the first lines whose self-capacitance sensing values exceed a preset range are determined; and then the self-capacitance mode is executed. In this mutual capacitance mode, mutual capacitance scanning is only performed on the lines whose self-capacitance sensing values among the first lines exceed the preset range, and the other lines among the first lines whose self-capacitance sensing values do not exceed the preset range. No mutual tolerance scan is performed.