Capacitive touch sensor

Abstract

The application discloses a capacitive touch sensor, which comprises a touch interface, a switch circuit and a sensing circuit. The switch circuit is switched according to self-capacitance and mutual-capacitance sensing conditions, and the same sensing circuit can provide self-capacitance mode and mutual-capacitance mode sensing, so that the structure of the circuit is simplified, and the circuit area and power consumption are saved. The sensing circuit adopts the principle of charge transfer to generate a stable output sensing voltage. Moreover, the differential mode can improve noise interference and improve the accuracy of judging the touch effect. The mutual-capacitance mode is operated again for the area that may have touch, so that the operation time of the mutual-capacitance mode is saved.

Description

Technical Field

[0001] This invention relates to a touch sensor, and more particularly to a capacitive touch sensor that can switch between self-capacitive, mutual-capacitive, and differential modes. Background Technology

[0002] Capacitive touch sensors, as an input tool for human-machine interfaces, are generally classified into self-capacitance and mutual capacitance. Self-capacitance refers to a sensor where the driving electrode and the sensing electrode are at the same point, and the touch effect is determined by detecting changes in the equivalent capacitance value of that electrode. Mutual capacitance, on the other hand, refers to a sensor where the driving electrode and the sensing electrode are two separate points, and the touch effect is determined by detecting changes in the equivalent capacitance value between the driving electrode and the sensing electrode. Each type of self-capacitance has its advantages and disadvantages. When the touch panel is divided into M*N touch channels, self-capacitance only requires M+N scans to complete the scan, while mutual capacitance requires M*N scans, taking longer to complete. However, self-capacitance has the problem of ghost points, which can lead to misjudgments in multi-touch scenarios, while mutual capacitance does not, thus enabling multi-touch functionality.

[0003] Taiwanese Patent No. I630523 discloses a touch device, its sensing method, and a touch sensing circuit. Compared to existing technologies, where different sensing modes require different sensing circuits, this patent discloses that by switching a switching circuit, the same sensing circuit can be used to achieve self-capacitive and mutual-capacitive multi-mode sensing, simplifying the circuit structure. However, its drawback is that it requires a specially designed touch panel. When the touch panel is divided into M*N touch channels, M*N traces are needed to connect to the switching circuit and the sensing circuit, while commonly used touch panels only require M+N traces to connect to the sensing circuit. Therefore, the complex panel wiring significantly reduces practicality.

[0004] Taiwanese Patent No. I489365 discloses a capacitive touch sensor and a method for switching between self-capacitance and mutual capacitance. This method integrates the driving unit and sensing unit by simulating the switching of a multiplexer, simplifying the circuit structure. This architecture, when used with a commonly used touch panel, requires only M+N traces to connect to the sensing circuit. However, its drawbacks include the need for separate voltage and current sources for self-capacitance and mutual capacitance modes, increasing power consumption. Furthermore, the operating method of this architecture results in fluctuations in the output sensing voltage, affecting the accuracy of touch response determination.

[0005] Chinese invention patent CN103197787 discloses a capacitive touch sensor that combines self-capacitance and mutual capacitance sensing values ​​to eliminate noise. However, its drawback is that executing self-capacitance mode and mutual capacitance mode requires a longer scanning time, which reduces the response speed of touch effect on large-size panels with a large number of channels.

[0006] Chinese invention patent CN103257760 discloses a time-saving scanning method for capacitive touch sensors. The concept involves first performing a preliminary estimation scan, and then performing a second-stage precise scan targeting areas where touch points may occur. This approach only includes the concept of mutual capacitance scanning; if the scanning results of self-capacitance mode are combined for evaluation, the scanning time can be further optimized.

[0007] To address the aforementioned problems, this invention provides a capacitive touch sensor that switches between self-capacitance and mutual capacitance. Compared to previous designs, the sensing circuit of this invention can achieve both self-capacitance and mutual capacitance sensing when paired with a commonly used touch panel, without requiring an additional current source, thus saving circuit area and power consumption. Furthermore, the differential mode design improves noise interference and enhances the accuracy of touch effect judgment. Combining the scanning results of self-capacitance and mutual capacitance modes for judgment saves scanning time and improves response speed. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a capacitive touch sensor.

[0009] The present invention provides a capacitive touch sensor, comprising a touch interface having a plurality of first lines and a plurality of second lines; a first switching circuit connected between the plurality of first lines and a mutual capacitance voltage; a second switching circuit receiving the plurality of first lines, the plurality of second lines and the self-capacitive voltage to generate a sensing input voltage; and a sensing circuit receiving the sensing input voltage to generate a sensing output voltage.

[0010] The aforementioned capacitive touch sensor includes a first switching circuit comprising at least one first switching unit; the at least one first switching unit being connected between the first line and the mutual capacitance voltage; a first sensing switch being connected between the touch interface and the output terminal of the at least one first switching unit; and a second sensing switch being connected between the output terminal of the switching circuit and the adjacent first switching unit.

[0011] The capacitive touch sensor described above, wherein the second switching circuit includes at least one second switching unit; the at least one second switching unit includes: a self-capacitive voltage switch connected between the self-capacitive voltage and the touch interface; a first sensing switch connected between the touch interface and the output terminal of the at least one second switching unit; and a second sensing switch connected between the output terminal of the switching circuit and the adjacent second switching unit.

[0012] The aforementioned capacitive touch sensor further includes a second self-capacitive switch connected between a second self-capacitive voltage and the touch interface.

[0013] The capacitive touch sensor described above includes the following operation modes for the first switching circuit and the second switching circuit: a mutual capacitance mode in which at least one first switching unit is sequentially turned on in the first switching circuit to provide the mutual capacitance voltage to the plurality of first lines; the first sensing switch is turned on in the at least one second switching unit, and the self-capacitive voltage switch, the second sensing switch, and the second self-capacitive switch are turned off; and a self-capacitive mode in which at least one first switching unit is turned off, and the at least one second switching unit turns on the first sensing switch or the second sensing switch according to the scanning channel, and turns on the self-capacitive voltage switch or the second self-capacitive switch according to the operation timing of the sensing circuit.

[0014] The aforementioned capacitive touch sensor, wherein the operation mode of the self-capacitive mode includes: an odd-numbered mode, in which both the first sensing switch and the second sensing switch are turned on in the at least one second switching unit with an odd number of units, and the self-capacitive voltage switch is turned on and the second self-capacitive switch is turned off according to the operation timing of the sensing circuit; and an even-numbered mode, in which both the first sensing switch and the second sensing switch are turned on in the at least one second switching unit with an even number of units, and the second self-capacitive switch is turned on and the self-capacitive voltage switch is turned off according to the operation timing of the sensing circuit; and an odd-numbered mode, in which both the first sensing switch and the second sensing switch are turned on in the at least one second switching unit with an even number of units, and the second self-capacitive switch is turned on and the self-capacitive voltage switch is turned off according to the operation timing of the sensing circuit.

[0015] The capacitive touch sensor described above includes one or more sensing units in its sensing circuit. If it includes only one sensing unit, whether in mutual capacitance mode or self-capacitance mode, the first sensing switch or the second sensing switch in the at least one second switching unit must be turned on sequentially to obtain the sensing output voltage of each first line or second line in sequence. If it includes multiple sensing units, the output terminal of the at least one second switching unit can be connected to the multiple sensing units respectively, and the first sensing switch or the second sensing switch can be turned on at the same time to obtain the sensing output voltage of the multiple sensing units.

[0016] The aforementioned capacitive touch sensor, wherein the sensing unit comprises: a first amplifier, the positive input terminal of which is connected to a reference voltage, the negative input terminal of which is connected to the output terminal of the switching circuit, and the negative input terminal of which is connected to the output terminal of which is connected to a first capacitor and a first timing switch; a second amplifier, the positive input terminal of which is connected to the reference voltage, the negative input terminal of which is connected to the output terminal of which is connected to a first resistor and a second timing switch, and the negative input terminal of which is connected to the output terminal of which is connected to a second capacitor and a third timing switch; wherein the output terminal of the second amplifier is the sensing output voltage.

[0017] The aforementioned capacitive touch sensor further includes a third amplifier. The positive input terminal of the third amplifier is connected to the reference voltage. A second timing negative terminal switch is connected between the negative input terminal of the third amplifier and the first resistor. A second negative terminal capacitor and a third timing negative terminal switch are connected between the negative input terminal of the third amplifier and the output terminal of the third amplifier. The output terminal of the third amplifier is the sensing negative output voltage.

[0018] The aforementioned capacitive touch sensor includes: a first timing sequence for turning on the first timing switch of the sensing unit, and if it is in self-capacitive mode, also turning on the self-capacitive voltage switch in the at least one second switching unit; a second timing sequence for turning on the second timing switch or the second timing negative terminal switch of the sensing unit; and a third timing sequence for turning on the third timing switch or the third timing negative terminal switch of the sensing unit.

[0019] The aforementioned capacitive touch sensor, wherein the sensing unit is connected to a switching circuit, receives at least two voltages including the sensing output voltage, the sensing output voltage of the adjacent sensing unit, and the reference voltage, outputs a positive output voltage and a negative output voltage of the switching circuit, and includes at least one of the following switching modes: 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 voltage and the negative output voltage of the switching circuit; and a second switching mode, selecting the sensing output voltage of the sensing unit and the reference voltage as the positive output voltage and the negative output voltage of the switching circuit.

[0020] The aforementioned capacitive touch sensor, wherein the sensing unit further includes a sensing negative output voltage and is connected to a switching circuit, receives at least two of the following voltages: 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 the reference voltage; outputs a switching circuit positive output voltage and a switching circuit negative output voltage; and includes at least one of the following switching modes: 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 voltage of the switching circuit. The switching circuit includes: an output voltage and a negative output voltage; a second switching mode in which the sensing output voltage of the sensing unit and the reference voltage are selected as the positive output voltage and negative output voltage of the switching circuit; a third switching mode in which the sensing negative output voltage of the sensing unit and the sensing negative output voltage of the adjacent sensing unit are selected as the positive output voltage and negative output voltage of the switching circuit; and a fourth switching mode in which the sensing negative output voltage of the sensing unit and the reference voltage are selected as the positive output voltage and negative output voltage of the switching circuit.

[0021] The aforementioned capacitive touch sensor further includes an analog-to-digital converter that receives the plurality of sensing output voltages, the plurality of sensing negative output voltages, the plurality of switching circuit positive output voltages, or the plurality of switching circuit negative output voltages, and outputs a digital signal.

[0022] In the aforementioned capacitive touch sensor, the plurality of first lines or the plurality of second lines in the touch interface are respectively connected to a reference capacitor switch, the other end of the reference capacitor switch is connected to a reference capacitor, and the reference capacitor is connected to a mutual capacitance second voltage; the plurality of reference capacitor switches can be turned on in mutual capacitance mode and turned off in self-capacitance mode.

[0023] The aforementioned capacitive touch sensor includes the following operation methods: first, executing the self-capacitive mode and determining which of the plurality of first lines has a self-capacitive sensing value exceeding a preset range; and then executing the mutual-capacitive mode, performing mutual-capacitive scanning only on the lines whose self-capacitive sensing values ​​exceed the preset range, while not performing mutual-capacitive scanning on the other lines whose self-capacitive sensing values ​​do not exceed the preset range.

[0024] The above-described operation method, where the capacitance sensor determines that the area is not touched, will not perform a mutual capacitance mode scan, which saves more scanning time compared to the previous method where each channel still needs to be scanned in mutual capacitance mode.

[0025] To further understand the features and technical content of the present invention, please refer to the following detailed description and accompanying drawings. However, these descriptions and drawings are only for illustrating the present invention and are not intended to limit the scope of the claims of the present invention in any way. Attached Figure Description

[0026] Figure 1 The architecture of a capacitive touch sensor according to a first embodiment of the present invention is illustrated.

[0027] Figure 2 Draw Figure 1 The architecture of the first switching circuit.

[0028] Figure 3 Draw Figure 1 The architecture of the second switching circuit.

[0029] Figure 4 Draw Figure 3 Another form of the second switching circuit.

[0030] Figure 5 Draw Figure 1 The architecture of the sensing circuit.

[0031] Figure 6 Draw Figure 5 The architecture of the sensing unit.

[0032] Figure 7 Draw Figure 6 Another form of sensing unit.

[0033] Figure 8 The complete circuit of the capacitive touch sensor according to the first embodiment of the present invention is illustrated.

[0034] Figure 9 The circuit diagram of a capacitive touch sensor according to a second embodiment of the present invention is shown.

[0035] Figure 10 The circuit diagram of a capacitive touch sensor according to a third embodiment of the present invention is shown.

[0036] Figure 11 An example diagram illustrating the operation timing of the capacitive touch sensor of the present invention is shown.

[0037] Figure label explanation: 10 - Touch interface; 101 - First line (TX); 102 - Second line (RX); C M- Mutual capacitive inductance capacitor; C S - Self-capacitive sensing capacitor; 20- First switching circuit; 201- First switching unit; 202- First switching unit; 30- Second switching circuit; 310- Second switching unit; 320- Second switching unit; 301- Self-capacitive voltage switch; 302- First sensing switch; 303- Second sensing switch; 304- Second self-capacitive 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-Third timing switch; 409-Third amplifier; 406N-Second timing negative terminal switch; 407N-Second negative terminal capacitor; 408N-Third timing negative terminal switch; 50-Analog-to-digital converter; 60-Switching circuit; 70-Reference capacitor switch; C70-Reference capacitor; V01-Mutual capacitance voltage; V02-Self capacitance voltage; V021-Second self capacitance voltage; V03-Sensed input voltage; V04-Sensed output voltage; V05-Reference voltage; V06-Positive output voltage of switching circuit; V06N-Negative output voltage of switching circuit; V07-Second mutual capacitance voltage. Detailed Implementation

[0038] The present invention will be described more clearly with reference to the following embodiments. Please note that the following description of the embodiments of the present invention is for illustrative purposes only; it does not imply that the invention has been described in detail or is limited to the form disclosed herein.

[0039] Please refer to the first embodiment of the present invention. Figure 1 The diagram illustrates the architecture of a capacitive touch sensor, including a touch interface 10 having a plurality of first lines (TX) 101 and a plurality of second lines (RX) 102; a first switching circuit 20 connected between the first lines (TX) 101 and a mutual capacitance voltage V01; a second switching circuit 30 receiving the plurality of first lines (TX) 101 and the plurality of second lines (RX) 102, and the self-capacitance voltage V02, and generating a sensing input voltage V03; a sensing circuit 40 receiving the sensing input voltage V03 and generating a sensing output voltage V04; and an analog-to-digital converter 50 receiving the sensing output voltage V04 and generating a digital output signal.

[0040] Figure 2 The circuit architecture of the first switching circuit 20 is illustrated. The first switching circuit 20 includes a plurality of first switching units 201, 202, each of which is connected between the first line (TX) 101 and the mutual capacitance voltage V01. The mutual capacitance voltage V01 is typically a square wave signal.

[0041] Figure 3 The circuit architecture of the second switching circuit 30 is shown in the figure. (C in the figure) M C represents the induced capacitance between the plurality of first lines (TX) 101 and the plurality of second lines (RX) 102 in the mutual capacitance mode. S This represents the sensing capacitance of the plurality of first lines (TX) 101 or the plurality of second lines (RX) 102 in the self-capacitive mode. The second switching circuit 30 includes a plurality of second switching units 310, 320, each of which includes a self-capacitive voltage switch 301 connected between the self-capacitive voltage V02 and the plurality of first lines (TX) 101 or the plurality of second lines (RX) 102; a first sensing switch 302 connected between the plurality of first lines (TX) 101 or the plurality of second lines (RX) 102 and the sensing input voltage V03; and a second sensing switch 303 connected between the sensing input voltage V03 and the adjacent second switching unit 320. The self-capacitive voltage V02 is typically a fixed DC signal.

[0042] Figure 4 Another circuit architecture for the second switching circuit 30 is illustrated. Figure 3 In contrast, the plurality of second switching units 310, 320 further include a second self-capacitive voltage V021 and a second self-capacitive switch 304, the second self-capacitive switch 304 being connected between the second self-capacitive voltage V021 and the plurality of first lines (TX) 101 or the plurality of second lines (RX) 102. The second self-capacitive voltage V021 is typically a fixed voltage DC signal.

[0043] The capacitive touch sensor described above includes the following operation modes for the first switching circuit 20 and the second switching circuit 30: a mutual capacitance mode, in which the plurality of first switching units 201, 202 are sequentially turned on to provide the mutual capacitance voltage V01 to the plurality of first lines (TX) 101, and each second switching unit 310, 320 turns on the first sensing switch 302 and turns off the self-capacitive voltage switch 301, the second sensing switch 303 and the second self-capacitive switch 304; and a self-capacitive mode, in which the first switching circuit 20 is turned off, and each second switching unit 310, 320 turns on the first sensing switch 302 or the second sensing switch 303 according to the scanning channel, and turns on the self-capacitive voltage switch 301 or the second self-capacitive switch 304 according to the operation timing of the sensing circuit 40.

[0044] In the self-capacitive mode, the operation of the plurality of second switching units 310, 320 of the aforementioned capacitive touch sensor includes: an odd-number mode, in which the first sensing switch 302 and the second sensing switch 303 of the odd-numbered second switching units 310 are both turned on, and the self-capacitive voltage switch 301 is turned on and the second self-capacitive switch 304 is turned off according to the operation timing of the sensing circuit 40; in the even-numbered second switching units 320, the first sensing switch 302 and the second sensing switch 303 are both turned off, and the second self-capacitive switch 304 is turned on and the self-capacitive voltage switch 301 is turned off according to the operation timing of the sensing circuit 40. In an even-numbered mode, the first sensing switch 302 and the second sensing switch 303 of the second switching unit 310, which are ordered in an odd-numbered sequence, are both closed, and the second self-capacitive switch 304 is turned on according to the operating timing of the sensing circuit 40, while the self-capacitive voltage switch 301 is turned off. In an even-numbered mode, the first sensing switch 302 and the second sensing switch 303 of the second switching unit 320, which are ordered in an even-numbered sequence, are both turned on, and the self-capacitive voltage switch 301 is turned on according to the operating timing of the sensing circuit 40, while the second self-capacitive switch 304 is turned off. If there are more second switching units, the rest are treated similarly.

[0045] Figure 5The diagram illustrates the architecture of the sensing circuit 40, which includes a plurality of sensing units 410 and 420. If there is only one set of sensing units 410, whether in mutual capacitance or self-capacitance mode, the first sensing switch 302 or the second sensing switch 303 in the plurality of second switching units 310 and 320 must be turned on sequentially to obtain the sensing output voltage V04 for each channel. If there are a plurality of sensing units 410 and 420, the output terminals V03 and V03-1 of the plurality of second switching units 310 and 320 can be connected to the plurality of sensing units 410 and 420 respectively, while simultaneously turning on the plurality of first sensing switches 302 or the plurality of second sensing switches 303, thereby obtaining the sensing output voltages V04 and V04-1 for the plurality of channels. Alternatively, a plurality of analog-to-digital converters 50 can be included to convert the sensing output voltages V04 and V04-1 for the plurality of channels into digital output signals.

[0046] Figure 6 The architecture of the plurality of sensing units 410, 420 is illustrated. Each sensing unit 410 includes: a first amplifier 401, the positive input terminal of which is connected to a reference voltage V05, the negative input terminal of which is connected to the sensing input voltage V03, and a first capacitor 402 and a first timing switch 403 connected between the negative input terminal and the output terminal of the first amplifier 401; and a second amplifier 404, the positive input terminal of which is connected to the reference voltage V05, the negative input terminal of which is connected to the output terminal of the first amplifier 401, a first resistor 405 and a second timing switch 406 connected between the negative input terminal and the output terminal of the second amplifier 404, and a second capacitor 407 and a third timing switch 408 connected between the negative input terminal and the output terminal of the second amplifier 404; wherein the output terminal of the second amplifier 404 is the sensing output voltage V04.

[0047] Figure 7 Another architecture of the sensing unit 410 is illustrated. Figure 6 In contrast, the sensing unit 410 further includes a third amplifier 409. The positive input terminal of the third amplifier 409 is connected to the reference voltage V04. A second timing negative terminal switch 406N is connected between the negative input terminal of the third amplifier 409 and the first resistor 405. A second negative terminal capacitor 407N and a third timing negative terminal switch 408N are connected between the negative input terminal and the output terminal of the third amplifier 409. The output terminal of the third amplifier 409 is the sensing negative output voltage V04N.

[0048] The capacitive touch sensor described above includes the following operating timing sequence: a first timing sequence, in which the first timing switch 403 of the plurality of sensing units 410, 420 is turned on; if it is in self-capacitive mode, the self-capacitive voltage switch 301 in the plurality of second switching units 310 is also turned on; a second timing sequence, in which the second timing switch 406 is turned on; if there is a second timing negative terminal switch 406N, then the second timing switch 406 and the second timing negative terminal switch 406N are turned on respectively; and a third timing sequence, in which the plurality of third timing switches 408 are turned on; if there is a third timing negative terminal switch 408N, then the third timing switch 408 and the third timing negative terminal switch 408N are turned on respectively.

[0049] Figure 8 A complete circuit diagram of the first embodiment of the present invention is shown. The second switching circuit 30 employs... Figure 4 The architecture of the sensing circuit 40 includes only one sensing unit 410, employing... Figure 6 The architecture is as follows. The analog-to-digital converter 50 receives the sensed output voltage V04 and converts it into a digital output signal.

[0050] Figure 9 A circuit diagram of a second embodiment of the present invention is shown. The second switching circuit 30 employs... Figure 4 The architecture of the sensing circuit 40 includes a plurality of sensing units 410, 420, ..., employing Figure 6 The architecture is as follows: If the touch interface 10 includes 50 first lines (TX) 101 and 30 second lines (RX) 102, then the second switching circuit 30 includes 30 sets of second switching units 310, 320, ..., and the sensing circuit 40 includes 30 sets of sensing units 410, 420, ... In the mutual capacitance mode, the corresponding first switching unit 201 is turned on in turn for each of the 50 first lines (TX) 101, and the 30 sets of sensing units 410, 420, ... can be activated simultaneously to detect the mutual capacitance value C of the 30 second lines (RX) 102. M The self-capacitance mode requires both odd and even modes to detect the self-capacitance capacitance C of the 30 second lines (RX)102. S Additionally, the 50 first lines (TX) 101 can also be connected to the second switching circuit 30 and the sensing circuit 40 to detect the self-capacitive capacitance value C of the 50 first lines (TX) 101. S .

[0051] Figure 9The capacitive touch sensor includes a plurality of sensing units 410, 420 connected to a switching circuit 60, which receives the sensing output voltage V04, the sensing output voltage V04-1 of the adjacent sensing unit 420, and the reference voltage V05, and outputs a positive output voltage V06 and a negative output voltage V06N of the switching circuit. The sensor includes two switching modes: a first switching mode, in which the sensing output voltage V04 and the sensing output voltage V04-1 of the adjacent sensing unit 420 are selected as the positive output voltage V06 and the negative output voltage V06N of the switching circuit; and a second switching mode, in which the sensing output voltage V04 and the reference voltage V05 are selected as the positive output voltage V06 and the negative output voltage V06N of the switching circuit.

[0052] Figure 9 The capacitive touch sensor, wherein the switching circuit 60 selects the second switching mode in the self-capacitive mode, can detect the self-capacitive sensing capacitance value C of the second line (RX) 102. S Selecting this second switching mode in the mutual capacitance mode allows detection of the mutual capacitance value C of the second line (RX) 102. M Selecting the first switching mode in the mutual capacitance mode allows detection of the mutual capacitance value C between two adjacent second lines in the second line (RX) 102. M The difference (C) M-2 -C M-1 ).

[0053] Figure 10 The circuit diagram illustrates a third embodiment of the present invention, wherein the second switching circuit 30 employs... Figure 4 The architecture of the sensing circuit 40 includes a plurality of sensing units 410, 420, ..., employing Figure 7The architecture further includes a sensing negative output voltage V04N, V04-1N, ... The switching circuit 60 receives at least two of the following voltages: the sensing output voltage V04, the sensing negative output voltage V04N, the sensing output voltage V04-1 of the adjacent sensing unit 420, the sensing negative output voltage V04-1N of the adjacent sensing unit 420, and the reference voltage V05. It outputs a switching circuit positive output voltage V06 and a switching circuit negative output voltage V06N. The switching circuit positive output voltage V06 and the switching circuit negative output voltage V06N include the following switching modes: a first switching mode selecting the sensing output voltage V04 and the adjacent sensing output voltage V04-1; a second switching mode selecting the sensing output voltage V04 and the reference voltage V05; a third switching mode selecting the sensing negative output voltage V04N and the adjacent sensing negative output voltage V04-1N; and a fourth switching mode selecting the sensing negative output voltage V04N and the reference voltage V05.

[0054] Figure 10 The capacitive touch sensor, wherein the switching circuit 60 selects the second switching mode or the fourth switching mode in the self-capacitive mode, can detect the self-capacitive sensing capacitance value C of the second line (RX) 102. S Selecting either the second or fourth switching mode in the mutual capacitance mode allows detection of the mutual capacitance value C of the second line (RX) 102. M Selecting either the first or third switching mode in the mutual capacitance mode allows detection of the mutual capacitance value C between two adjacent second lines in the second line (RX) 102. M The difference (C) M-2 -C M-1 ).

[0055] Figure 8 , Figure 9 or Figure 10 The capacitive touch sensor further includes an analog-to-digital converter 50, which receives the sensing output voltage V04, the sensing negative output voltage V04N, the switching circuit positive output voltage V06, or the switching circuit negative output voltage V06N, and outputs a digital signal.

[0056] Figure 10 The capacitive touch sensor is wherein the plurality of second lines (RX) 102 in the touch interface 10 are respectively connected to a reference capacitor switch 70, the other end of the reference capacitor switch 70 is connected to a reference capacitor C70, and the reference capacitor C70 is connected to a mutual capacitance second voltage V07; the reference capacitor switch 70 can be turned on in mutual capacitance mode and turned off in self-capacitance mode. Figure 1 , Figure 8 and Figure 9An embodiment may also include the reference capacitor switch 70, the reference capacitor C70, and the mutual capacitance second voltage V07. Its function is to sense the mutual capacitance value C. M A baseline value can be deducted to improve the uniformity of the sensing results.

[0057] Figure 11 The diagram illustrates an example of the operating timing of the capacitive touch sensor of the present invention. Both the mutual capacitance voltage V01 and the second mutual capacitance voltage V07 are square wave signals. The first switching circuit 20 and the second switching circuit 30 switch according to the aforementioned mutual capacitance mode. The reference voltage V05 is set to half the power supply voltage (VDD / 2). The switching circuit 60 selects the switching mode based on the potential of the mutual capacitance voltage V01: a high potential selects the second switching mode, and a low potential selects the fourth switching mode. The circuit sequentially enters the first timing sequence, the second timing sequence, and the third timing sequence, utilizing the principle of charge transfer to transfer the mutual capacitance capacitance value C. M It is converted into a sensing output voltage V04, and finally converted into a digital signal by the analog-to-digital converter 50.

[0058] The self-capacitive mode operation timing of the capacitive touch sensor of the present invention can also be referenced. Figure 11 The first switching circuit 20 and the second switching 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, and the reference voltage V05 is set to half of the power supply voltage (VDD / 2). The switching circuit 60 can also 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 when the potential is low, the fourth switching mode is selected. The circuit sequentially enters the first timing sequence, the second timing sequence, and the third timing sequence. Utilizing the principle of charge transfer, the self-capacitance induced capacitance value C is... S It is converted into a sensing output voltage V04, and finally converted into a digital signal by the analog-to-digital converter 50.

[0059] The aforementioned capacitive touch sensor includes the following operation method: first, executing the self-capacitive mode and determining the lines in the plurality of first lines (TX) 101 whose self-capacitive sensing values ​​exceed a preset range; and then executing the mutual capacitance mode, performing mutual capacitance scanning only on the lines in the plurality of first lines (TX) 101 whose self-capacitive sensing values ​​exceed the preset range, while not performing mutual capacitance scanning on the other lines in the plurality of first lines (TX) 101 whose self-capacitive sensing values ​​do not exceed the preset range, thereby saving the operation time of the 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 firstly. If it is determined that the self-capacitance sensing value of 3 of the first lines (TX) 101 exceeds the preset range, it means that only these 3 first lines (TX) 101 may be touched by a finger. When operating the mutual capacitance mode next, only these 3 first lines (TX) 101 need to be scanned for mutual capacitance to determine the touch effect. The remaining 47 first lines (TX) 101 do not need to be scanned for mutual capacitance. The mutual capacitance mode originally needs to sense and process 50 x 30 = 1500 mutual capacitance sensing data. In the above example, only 3 x 30 = 90 mutual capacitance sensing data need to be sensed and processed, which can save the operation time of the mutual capacitance mode and improve the reporting rate.

[0060] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A capacitive touch sensor, characterized in that, Include: A touch interface with multiple first lines and multiple second lines; A first switching circuit is connected between the plurality of first lines and a mutual capacitance voltage; A second switching circuit receives the plurality of first lines and the plurality of second lines, as well as a self-capacitive voltage, to generate a sensing input voltage; and A sensing circuit receives the sensing input voltage and generates a sensing output voltage. The second switching circuit includes a plurality of second switching units; the plurality of second switching units includes: A self-capacitive voltage switch is connected between the self-capacitive voltage and the touch interface; A first sensing switch is connected between the touch interface and the output terminals of the plurality of second switching units; and A second sensing switch is connected between the output terminal of the switching circuit and the adjacent second switching unit.

2. The capacitive touch sensor as described in claim 1, characterized in that, The first switching circuit includes at least one first switching unit; the at least one first switching unit is connected between the first line and the mutual capacitance voltage.

3. The capacitive touch sensor as described in claim 1, characterized in that, The second switching unit further includes a second self-capacitive switch connected between a second self-capacitive voltage and the touch interface.

4. The capacitive touch sensor as described in claim 3, characterized in that, Given: In a mutual capacitance mode, at least one first switching unit is sequentially turned on in the first switching circuit to provide the mutual capacitance voltage to the plurality of first lines; the first sensing switch is turned on in the plurality of second switching units, and the self-capacitive voltage switch, the second sensing switch, and the second self-capacitive switch are turned off. as well as In a self-capacitance mode, the at least one first switching unit is turned off, and the plurality of second switching units turn on the first sensing switch or the second sensing switch according to the scanning channel, and turn on the self-capacitance voltage switch or the second self-capacitance switch according to the operating timing of the sensing circuit, so as to provide the self-capacitance voltage or the second self-capacitance voltage to the plurality of second lines or the plurality of first lines.

5. The capacitive touch sensor as described in claim 4, characterized in that, This self-contained mode includes: In an odd-numbered mode, in the plurality of second switching units arranged in an odd number, both the first sensing switch and the second sensing switch are turned on, and the self-capacitive voltage switch is turned on and the second self-capacitive switch is turned off according to the operating timing of the sensing circuit; in the plurality of second switching units arranged in an even number, both the first sensing switch and the second sensing switch are turned off, and the second self-capacitive switch is turned on and the self-capacitive voltage switch is turned off according to the operating timing of the sensing circuit. as well as In an even-numbered mode, in the plurality of second switching units arranged in an even number, both the first sensing switch and the second sensing switch are turned on, and the second self-capacitive switch is turned on and the self-capacitive voltage switch is turned off according to the operating timing of the sensing circuit; in the plurality of second switching units arranged in an odd number, both the first sensing switch and the second sensing switch are turned off, and the self-capacitive voltage switch is turned on and the second self-capacitive switch is turned off according to the operating timing of the sensing circuit.

6. The capacitive touch sensor as described in claim 4, characterized in that, The sensing circuit includes one or more sensing units. If it includes only one sensing unit, during scanning, the first sensing switch or the second sensing switch in the plurality of second switching units must be turned on in sequence to obtain the sensing output voltage of each first line or second line in sequence. If it includes a plurality of sensing units, the output terminals of the plurality of second switching units are respectively connected to the plurality of sensing units, and the first sensing switch or the second sensing switch is turned on at the same time to obtain the sensing output voltage of the plurality of sensing units.

7. The capacitive touch sensor as described in claim 6, characterized in that, The sensing unit includes: A first amplifier, the positive input terminal of which is connected to a reference voltage, the negative input terminal of which is connected to the output terminal of the switching circuit, and 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. as well as A second amplifier is provided, the positive input terminal of which is connected 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. A second capacitor and a third timing switch are connected between the negative input terminal of the second amplifier and the output terminal of the second amplifier. The output terminal of the second amplifier is the sensed output voltage.

8. The capacitive touch sensor as described in claim 7, characterized in that, The sensing unit further includes a third amplifier, the positive input terminal of which is connected to the reference voltage, a second timing negative terminal switch between the negative input terminal of the third amplifier and the first resistor, and a second negative terminal capacitor and a third timing negative terminal switch between the negative input terminal of the third amplifier and the output terminal of the third amplifier, wherein the output terminal of the third amplifier is the sensing negative output voltage.

9. The capacitive touch sensor as described in claim 8, characterized in that, In a first timing sequence, the first timing switch of the sensing unit is turned on. If it is in self-capacitive mode, the self-capacitive voltage switch in the plurality of second switching units is also turned on. In a second timing sequence, the second timing switch or the second timing negative terminal switch of the sensing unit is turned on; as well as In a third timing sequence, the third timing switch or the third timing negative terminal switch of the sensing unit is turned on.

10. The capacitive touch sensor as described in claim 7, characterized in that, The sensing unit is connected to a switching circuit, receives at least two voltages from the sensing output voltage, the sensing output voltage of an adjacent sensing unit, and the reference voltage, and outputs a positive output voltage and a negative output voltage of the switching circuit. It also includes: In a first switching mode, the sensing output voltage of the sensing unit and the sensing output voltage of the adjacent sensing unit are selected as the positive output voltage and negative output voltage of the switching circuit, respectively. as well as In a second switching mode, the sensing output voltage of the sensing unit and the reference voltage are selected as the positive output voltage and negative output voltage of the switching circuit, respectively.

11. The capacitive touch sensor as described in claim 8, characterized in that, The sensing unit has a sensing negative output voltage and is connected to a switching circuit. It receives at least two voltages from the sensing output voltage, the sensing negative output voltage, the sensing output voltage of an adjacent sensing unit, the sensing negative output voltage of the adjacent sensing unit, and the reference voltage. It outputs a switching circuit positive output voltage and a switching circuit negative output voltage, and has the following switching modes: In a first switching mode, the sensing output voltage of the sensing unit and the sensing output voltage of the adjacent sensing unit are selected as the positive output voltage and negative output voltage of the switching circuit, respectively. In a second switching mode, the sensing output voltage of the sensing unit and the reference voltage are selected as the positive output voltage and negative output voltage of the switching circuit, respectively. In a third switching mode, the negative output voltage of the sensing unit and the negative output voltage of the adjacent sensing unit are selected as the positive output voltage and negative output voltage of the switching circuit, respectively. as well as In the fourth switching mode, the sensing negative output voltage and the reference voltage of the sensing unit are selected as the positive output voltage and negative output voltage of the switching circuit, respectively.

12. The capacitive touch sensor as described in claim 10, characterized in that, It further includes an analog-to-digital converter that receives the plurality of sensed output voltages, the plurality of sensed negative output voltages, the plurality of switching circuit positive output voltages, or the plurality of switching circuit negative output voltages, and outputs a digital signal.

13. The capacitive touch sensor as described in claim 4, characterized in that, The plurality of first lines or the plurality of second lines in the touch interface are each connected to a reference capacitor switch, the other end of which is connected to a reference capacitor, which is connected to a mutual capacitance second voltage; the plurality of reference capacitor switches are turned on in mutual capacitance mode and turned off in self-capacitance mode.

14. The capacitive touch sensor as described in claim 4, characterized in that, First, execute the self-capacitance mode and determine which of the plurality of first lines has a self-capacitance sensing value that exceeds a preset range; as well as When the mutual capacitance mode is executed again, mutual capacitance scanning is performed only on the lines whose self-capacitance sensing values ​​exceed the preset range among the plurality of first lines, while the other lines whose self-capacitance sensing values ​​do not exceed the preset range are not subjected to mutual capacitance scanning.

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