Touch detection device and method

Abstract

The embodiment of the invention discloses a touch detection device and method. The device comprises at least two touch electrodes, a channel selection module, a switch module, an external capacitor and a detection module, one end of each touch electrode and one end of the external capacitor are grounded, the second end of each touch electrode is correspondingly connected with one input end of the channel selection module, the switch module is communicated with the common end and the second end of the switch module when the touch electrodes discharge, and is communicated with the common end and the first end of the switch module when the touch electrodes are charged; when the touch electrode charges the external capacitor, the common end and the third end of the switch module are connected; the channel selection module sequentially gates any input end and any output end, and when the external capacitor is charged to a reference voltage signal, the detection module performs touch detection according to the number of times that the common end and the third end are communicated by the switch module. The problem that a plug-in capacitor occupies a large amount of resources is solved, and the hardware cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of touch technology, and in particular to a touch detection device and method. Background Art

[0002] With the rapid development of electronic devices today, touch technology has become one of the key technologies that are indispensable for all kinds of devices. Whether it is smartphones, tablets, smart home appliances or industrial control equipment, the application range of touch detection technology is extremely wide.

[0003] In traditional touch detection solutions, each channel is required to be connected to an external capacitor, which leads to a significant increase in production costs. Secondly, both ends of the external capacitor need to be connected to the IO port of the microcontroller unit (MCU), which takes up a lot of MCU resources. In addition, the external capacitor has extremely high requirements for power supply stability during each charging process. Once the power supply fluctuates, it will cause significant interference to the touch detection results, affecting the accuracy and stability of the touch, thereby reducing the user experience. As competition in electronic products becomes increasingly fierce, cost control requirements are becoming more and more stringent. In addition to component costs, there are also wiring costs and MCU chip resource costs that need to be managed. Summary of the Invention

[0004] The present invention provides a touch detection device and method to solve the problem that external capacitors occupy a large amount of resources.

[0005] The present invention provides a touch detection device, comprising: at least two touch electrodes, a channel selection module, a switch module, an external capacitor and a detection module;

[0006] The first end of each touch electrode and the second end of the external capacitor are grounded, the second end of each touch electrode is correspondingly connected to an input end of the channel selection module, the output end of the channel selection module is connected to the common end of the switch module, the first end of the switch module is connected to the power end, the second end of the switch module is connected to the ground, and the third end of the switch module is connected to the first end of the external capacitor. The switch module is configured to connect the common end and the second end of the switch module when the touch electrode is discharging, connect the third end and the second end of the switch module when the external capacitor is discharging, connect the common end and the first end of the switch module when the touch electrode is charging, and connect the common end and the third end of the switch module when the touch electrode is charging the external capacitor. The channel selection module is configured to select any input end and output end. The input end of the detection module is connected to the first end of the external capacitor. The detection module is configured to perform touch detection based on the number of times the switch module connects the common end and the third end when the external capacitor is charged to a reference voltage signal.

[0007] Optionally, the detection module includes a voltage detection unit and a control unit, the first input end of the voltage detection unit is connected to the reference voltage signal end, the second input end of the voltage detection unit is connected to the first end of the external capacitor, the input end of the control unit is connected to the output end of the voltage detection unit, and the output end of the control unit is connected to the first input end of the voltage detection unit, and the voltage detection unit is used to output a charging termination control signal when the charging voltage of the external capacitor is greater than or equal to the reference voltage signal; the control unit is used to perform touch detection according to the number of times the switch module connects the common end and the third end when receiving the charging termination control signal.

[0008] Optionally, the switch module includes a first switch, a second switch and a third switch, the first end of the first switch is connected to the power supply end, the second end of the first switch is connected to the first end of the second switch, the first end of the third switch and the output end of the channel selection module, the second end of the second switch is connected to the ground, and the second end of the third switch is connected to the first end of the external capacitor.

[0009] Optionally, the touch detection device further includes a pre-charging module, which is connected to the external capacitor and is used to pre-charge the external capacitor to a first voltage; wherein the first voltage is lower than a reference voltage signal.

[0010] Optionally, the pre-charge module includes a voltage source and a fourth switch;

[0011] The voltage source is connected to the first end of the fourth switch, and the second end of the fourth switch is connected to the first end of the external capacitor; or,

[0012] The touch detection device also includes a power supply module, which is used to provide a power supply voltage to the power supply end in a first mode. The power supply module is multiplexed as the voltage source, which is used to provide the first voltage to the power supply end in a second mode; the first switch and the third switch are multiplexed as the fourth switch.

[0013] Optionally, the switch module is also used to connect the first end and the third end when the external capacitor is pre-charged; the detection module is also used to control the switch module to connect the first end and the third end when the external capacitor is pre-charged to a first voltage; wherein, the first voltage is less than the reference voltage signal.

[0014] According to another aspect of the present invention, a touch detection method is provided, which can be implemented using the touch detection device described in any of the above embodiments. The method includes:

[0015] The first step is to select an input terminal and an output terminal of the channel selection module;

[0016] Step 2: Control the switch module to connect the common terminal and the second terminal to discharge the touch electrode;

[0017] Step 3: Control the switch module to connect the third terminal to the second terminal to discharge the external capacitor;

[0018] Step 4: Control the switch module to connect the common terminal and the first terminal to charge the touch electrode;

[0019] Step 5: Control the switch module to connect the common terminal and the third terminal to charge the external capacitor;

[0020] Step 6: Repeat the fourth and fifth steps to charge the external capacitor to a reference voltage signal;

[0021] Step 7: Perform touch detection according to the number of times the switch module connects the common terminal and the third terminal.

[0022] Optionally, the touch detection device further includes a pre-charging module connected to the external capacitor, and before the fifth step, further includes:

[0023] The pre-charge module is controlled to be connected to the external capacitor to pre-charge the external capacitor to a first voltage; wherein the first voltage is less than a reference voltage signal.

[0024] Optionally, before step 5, also include:

[0025] The third end of the switch module is controlled to be connected to the first end, so as to pre-charge the external capacitor to a first voltage.

[0026] Optionally, after step 7, also include:

[0027] The external capacitor is discharged to a first voltage.

[0028] The technical solution of the present invention's embodiment allows for arbitrary selection of touch electrodes through a channel selection module, enabling expansion to more touch channels. Multiple touch electrodes can perform touch detection sequentially, each sharing an external capacitor. A switch module controls the charging and discharging of the touch electrodes and external capacitor, reducing interference from power supply fluctuations on the detection signal. This solves the problem of large external capacitor usage and reduces hardware costs.

[0029] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a structural diagram of touch technology in related technology;

[0032] Figure 2 is a structural diagram of a touch detection device provided by an embodiment of the present invention;

[0033] Figure 3 is a structural diagram of another touch detection device provided by an embodiment of the present invention;

[0034] Figure 4 is a structural diagram of another touch detection device provided by an embodiment of the present invention;

[0035] Figure 5 is a circuit schematic diagram of a touch detection device provided by an embodiment of the present invention;

[0036] Figure 6 is a flow chart of a touch detection method provided by an embodiment of the present invention;

[0037] Figure 7 is a charge and discharge waveform diagram of a touch electrode provided by an embodiment of the present invention;

[0038] Figure 8 It is a waveform diagram of the external capacitor during the charging process of the present invention;

[0039] Figure 9 This is a flow chart of another touch detection method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] Related technologies such as touch technology Figure 1 As shown, the first end of the parasitic capacitor Cx of the touch copper sheet is grounded, and the second end of the parasitic capacitor Cx of the touch copper sheet is connected to the first end of the external capacitor Cs and the first end of switch Sn1. The second end of switch Sn1 is connected to the negative power supply GND. The second end of the external capacitor Cs is connected to the second end of switch Sn2 and the first end of switch Sn3. The first end of switch Sn2 is connected to the power supply VDD. The first end of switch Sn2 is also connected to the first end of switch Sn3, and the second end of switch Sn3 is connected to the negative power supply GND. The external capacitor Cs is of Nf level, while the parasitic capacitor Cx of the touch copper sheet is generally around 10 pf. That is, the capacitance of the external capacitor Cs is much larger than the capacitance of the parasitic capacitor Cx of the touch copper sheet. The touch detection steps are as follows: First, close switch Sn1, open switch Sn2, and close switch Sn3 to discharge the external capacitor Cs and the parasitic capacitor Cx of the touch copper sheet. Second, open switches Sn1, Sn2, and Sn3. In the third step, switches Sn1 and Sn3 are opened, and switch Sn2 is closed. The external capacitor Cs and the parasitic capacitor Cx of the copper sheet are connected in series, and current flows, reaching a balanced voltage across the external capacitor Cs. In the fourth step, switch Sn2 is opened, and Sn1 is closed. The parasitic capacitor Cx of the copper sheet is discharged, and the voltage difference across the external capacitor Cs remains unchanged. In the fifth step, steps 3 and 4 are repeated until the voltage across the external capacitor Cs reaches a certain threshold voltage, and the number of times Sn2 is closed is counted. When a finger touches the copper sheet, the capacitance of the parasitic capacitor Cx of the copper sheet increases. This is determined by the material and thickness of the cover on the parasitic capacitor Cx of the copper sheet. In this case, the number of times switch Sn2 is closed when a finger is touched decreases, thereby counting the presence of a finger in the system. The above solution requires capacitors for each channel, which complicates board wiring and increases component cost. Furthermore, the external capacitors occupy a large number of MCU IO ports, which consumes a large amount of MCU resources. The external capacitor needs to be charged every time. If the power supply fluctuates during this process, it will have a greater impact on the results.

[0043] In view of this, Figure 2 This is a structural diagram of a touch detection device provided by an embodiment of the present invention. This embodiment is applicable to scenarios where it is necessary to reliably detect small capacitance changes, such as consumer electronics and smart homes, automotive electronics, wearable devices, and medical equipment. Figure 2 As shown, the device includes: at least two touch electrodes 101, a channel selection module 102, a switch module 103, an external capacitor 104 and a detection module 105;

[0044] The first end of each touch electrode 101 and the second end of the external capacitor 104 are grounded, the second end of each touch electrode 101 is connected to an input end of the channel selection module 102, the output end of the channel selection module 102 is connected to the common end of the switch module 103, the first end of the switch module 103 is connected to the power supply end Vc, the second end of the switch module 103 is connected to the ground, and the third end of the switch module 103 is connected to the first end of the external capacitor 104. The switch module 103 is used to connect the common end and the second end of the switch module 103 when the touch electrode 101 is discharged. When the touch electrode 104 is discharging, the third end and the second end of the switch module 103 are connected; when the touch electrode 101 is charging, the common end and the first end of the switch module 103 are connected; when the touch electrode 101 charges the external capacitor 104, the common end and the third end of the switch module 103 are connected; the channel selection module 102 is used to select any input end and output end; the input end of the detection module 105 is connected to the first end of the external capacitor 104, and the detection module 105 is used to perform touch detection according to the number of times the switch module 103 connects the common end and the third end when the external capacitor 104 is charged to the reference voltage signal.

[0045] Among them, the touch electrode 101 can be used to sense touch operations. The parasitic capacitance of the touch electrode 101 is at the Pf level. When a touch occurs, parasitic capacitance will be generated between the finger and the touch electrode 101, and the capacitance of the touch channel will change. The channel selection module 102 can select any one of the multiple touch electrodes 101 and connect it to the output end, and can perform touch detection on different touch electrodes 101 in turn. For example, in a capacitive touch system, multiple touch electrodes 101 are arranged in a matrix, and each touch electrode 101 is scanned in turn by the channel selection module 102. The channel selection module 102 can select a specific electrode in a row or column for touch detection. The switch module 103 may include multiple switches, and the touch electrode 101 and the external capacitor 104 are charged and discharged by setting the states of the multiple switches. The external capacitor 104 can be used to store charge, and the external capacitor 104 is at the Nf level. The detection module 105 may include a voltage detector. The detection module 105 can perform real-time detection of the charging voltage of the external capacitor 104. The charge of the parasitic capacitance of the touch electrode 101 is transferred to the external capacitor 104, and the charge of the external capacitor 104 increases. According to the charge formula Q=CU, the voltage of the external capacitor 104 gradually increases. When the voltage of the external capacitor 104 reaches the reference voltage signal, the detection module 105 performs touch detection based on the number of times the switch module connects the common terminal and the third terminal. The conductive area of ​​the touch area corresponding to the touch electrode 101 can be copper or a spring. When a finger touches the touch area corresponding to the touch electrode 101, the capacitance near the touch electrode 101 will increase. When there is a finger touch, the number of times the touch electrode 101 charges the external capacitor 104 will decrease. By measuring the number of times the touch electrode 101 charges the external capacitor 101, it can be determined whether there is a touch. The channel selection module 102 can select one touch electrode 101 in sequence, and implement touch detection of multiple touch electrodes 101 in combination with the timing control of the switch module 103 .

[0046] Specifically, the channel selection module 102 selects the touch electrode 101 connected to any input terminal for output, and the switch module 103 connects the common terminal and the second terminal. At this time, the charge accumulated in the touch electrode 101 can be released to the ground through the connected path, completing the discharge process. The switch module 103 connects the third terminal and the second terminal, and the charge stored in the external capacitor 104 is released to the ground through this path, completing the discharge process. The switch module 103 connects the common terminal and the first terminal, and the power supply voltage of the power supply terminal Vc can charge the parasitic capacitance of the touch electrode 101, causing it to accumulate charge. The switch module 103 connects the common terminal and the third terminal, and the charge on the parasitic capacitance of the touch electrode 101 can be transferred to the external capacitor 104, and the amount of charge on the external capacitor 104 increases. By repeatedly charging the parasitic capacitance of the touch electrode 101 and transferring the charge from the parasitic capacitance of the touch electrode 101 to the external capacitor 104, the charge in the external capacitor 104 gradually increases, and the voltage of the external capacitor 104 also gradually increases. When the detection module 105 detects that the voltage of the external capacitor 104 reaches the reference voltage signal Vref, the charging of the external capacitor 104 by the touch electrode 101 is completed. Touch detection is achieved by the difference in the number of times the touch electrode 101 charges the external capacitor 104 when a finger touches it or not.

[0047] For example, assuming the parasitic capacitance of touch electrode 101 is 1 Pf, external capacitor 104 is 10 Nf, the voltage of power supply terminal Vc is 3 V, the voltage of reference voltage signal Vref is 1.5 V, and the parasitic capacitance generated by a finger touch is 1 Pf, calculations show that when there is no finger touch, touch electrode 101 needs to charge and discharge external capacitor 104 694 times. When there is a finger touch, touch electrode 101 needs to charge and discharge external capacitor 104 631 times, resulting in a finger touch effect of 63 times.

[0048] The technical solution of the present invention's embodiment allows for arbitrary selection of touch electrodes through a channel selection module, enabling expansion to more touch channels. Multiple touch electrodes can perform touch detection sequentially, each sharing an external capacitor. Timing control by the switch module enables the charging and discharging of the touch electrodes and external capacitor, reducing interference from power supply fluctuations on the detection signal. This solves the problem of large external capacitor resource requirements and reduces hardware costs.

[0049] Figure 3 FIG. 1 is a structural diagram of another touch detection device provided by an embodiment of the present invention. Figure 3As shown, the detection module 105 includes a voltage detection unit 1051 and a control unit 1052. The first input end of the voltage detection unit 1051 is connected to the reference voltage signal end, the second input end of the voltage detection unit 1051 is connected to the first end of the external capacitor 104, the input end of the control unit 1052 is connected to the output end of the voltage detection unit 1051, and the output end of the control unit 1052 is connected to the first input end of the voltage detection unit 1051. The voltage detection unit 1051 is used to output a charging end control signal when the charging voltage of the external capacitor 104 is greater than or equal to the reference voltage signal Vref; the control unit 1052 is used to perform touch detection according to the number of times the switch module 103 connects the common end and the third end when receiving the charging end control signal.

[0050] The voltage detection unit 1051 can be a voltage comparator, which is used to monitor the charging voltage of the external capacitor 104 in real time and output a charging end control signal when it is greater than or equal to the reference voltage signal Vref. The voltage of the reference voltage signal Vref is less than the voltage of the power supply terminal Vc. When the charge of the parasitic capacitance of the touch electrode 101 is transferred to the external capacitor 104, the charge amount of the external capacitor 104 gradually increases, and the voltage of the external capacitor 104 also gradually rises. The voltage detection unit 1051 continuously compares the voltage of the external capacitor 104 with the reference voltage signal Vref. When the voltage of the external capacitor 104 is less than the reference voltage signal Vref, the current charging state is maintained; when the voltage of the external capacitor 104 is greater than or equal to the reference voltage signal Vref, the charging end control signal is output to stop the touch electrode 101 from charging the external capacitor 104. When receiving the charging end control signal, the control unit 1052 can perform touch detection based on the number of times the switch module 103 connects the common terminal and the third terminal.

[0051] In some optional embodiments of the present invention, continue to refer to Figure 3 The switch module 103 includes at least a first switch S1, a second switch S2, and a third switch S3. The first end of the first switch S1 is connected to the power supply end, the second end of the first switch S1 is connected to the first end of the second switch S2, the first end of the third switch S3, and the output end of the channel selection module, the second end of the second switch S2 is connected to the ground, and the second end of the third switch S3 is connected to the first end of the external capacitor 104.

[0052] Among them, the first end of the first switch S1 is connected to the power supply terminal Vc, the second end of the first switch S1 is connected to the first end of the second switch S2 and the first end of the third switch S3 as a common terminal, the second end of the second switch S2 is connected to the ground, and the second end of the third switch S3 is connected to the first end of the external capacitor 104. The switch 103 module realizes the charging and discharging of the touch electrode 101 and the external capacitor 104 by controlling the conduction and shutdown of the three switches.

[0053] Specifically, only the second switch S2 is closed, and the first switch S1 and the third switch S3 are disconnected to enable the touch electrode 101 to discharge. The charge of the touch electrode 101 can be cleared to prepare for charging. The second switch S2 and the third switch S3 are closed, and the first switch S1 is disconnected to enable the external capacitor 104 to discharge. Ensure that its initial voltage is zero to prevent the residual charge from the previous operation from affecting the current detection. Only the first switch S1 is closed, and the second switch S2 and the third switch S3 are disconnected. The power supply terminal Vc can charge the touch electrode 101. The amount of charge is related to the parasitic capacitance of the touch electrode 101. When a finger touches, parasitic capacitance is generated between the finger and the touch electrode 101, the capacitance of the touch channel increases, and the charging time is prolonged. The third switch S3 is closed and the first switch S1 and the second switch S2 are disconnected to enable the touch electrode 101 to charge the external capacitor 104. The charge of the touch electrode 101 is transferred to the external capacitor 104 through the switch module 103.

[0054] Figure 4 is a structural diagram of another touch detection device provided by an embodiment of the present invention. In some optional embodiments of the present invention, such as Figure 4 As shown, a pre-charge module 106 is further included. The pre-charge module 106 is connected to the external capacitor 104 and is used to pre-charge the external capacitor 104 to a first voltage; wherein the first voltage is less than the reference voltage signal Vref.

[0055] Among them, the pre-charge module 106 is connected to the first end of the external capacitor 104 and can be controlled by an independent switch. The pre-charge module 106 pre-charges the external capacitor 104 to a first voltage. A low-voltage stabilized voltage source can be used as a power source. During touch detection, pre-charging the external capacitor 104 to the first voltage can be performed before the charging stage of the external capacitor 104. It takes a long time for the external capacitor 104 to charge from 0V to the reference voltage signal Vref. The charging time of the external capacitor 104 from the first voltage to the reference voltage signal Vref is shortened, and power consumption can be reduced at the same time. Pre-charging narrows the effective detection voltage range, making the voltage impact corresponding to the small capacitance change caused by touch easier to detect. The power supply terminal Vc can be provided with a first voltage by the power supply module, the first switch S1 and the third switch S3 are closed, and the first voltage output by the power supply module is used to pre-charge the external capacitor 104 to the first voltage. The external capacitor 104 can also be pre-charged to a first voltage through the power supply terminal Vc. The first voltage is less than the reference voltage signal Vref, and the reference voltage signal Vref is less than the power supply terminal Vc. The control unit 1052 can change the reference voltage signal connected to the first input terminal of the voltage detection unit 1051 to the first voltage, close the first switch S1 and the third switch S3, and charge the external capacitor 104. When the external capacitor 104 is charged to the first voltage, the voltage detection unit 1051 outputs a charging end control signal to disconnect the first switch S1 and the third switch S3. At this time, the external capacitor 104 has been charged to the first voltage.

[0056] In some optional embodiments of the present invention, continue to refer to Figure 4 , the pre-charge module 106 includes a voltage source V1 and a fourth switch S4;

[0057] The voltage source V1 is connected to the first end of the fourth switch S4 , and the second end of the fourth switch S4 is connected to the first end of the external capacitor 104 ; or

[0058] The touch detection device also includes a power supply module, which is used to provide a power supply voltage to the power supply terminal Vc in the first mode. The power supply module is multiplexed as a voltage source V1, which is used to provide a first voltage to the power supply terminal Vc in the second mode; the first switch S1 and the third switch S3 are multiplexed into a fourth switch S4.

[0059] The voltage source V1 can be a dedicated voltage source that can output a stable first voltage that is lower than the reference voltage signal Vref. The first end of the fourth switch S4 is connected to the output end of the voltage source V1. The second end of the fourth switch S4 is connected to the first end of the external capacitor 104. By closing the fourth switch S4, the voltage source V1 pre-charges the external capacitor 104. When the external capacitor 104 is charged to the first voltage, the fourth switch S4 is opened. The first mode is a normal power supply mode, in which the power supply terminal Vc charges the touch electrode 101. The second mode is a voltage source reuse mode, in which the external capacitor 104 is pre-charged. In the first mode, the power module can provide a power supply voltage to the power supply terminal Vc. In the second mode, the power module can be reused as the voltage source V1 to provide the first voltage. Reusing the power module reduces the need for additional voltage source circuits, thereby reducing costs. In the first mode, the first switch S1 and the third switch S3 independently control the conduction of different circuit paths. In the second mode, the first switch S1 and the third switch S3 are combined into a logical fourth switch S4. By multiplexing switches, the number of switches is reduced and the circuit layout is optimized.

[0060] Specifically, when precharging the external capacitor 104, the power module can provide a first voltage to the power supply terminal Vc, the first switch S1 and the third switch S3 are closed, and the first voltage output by the power module is used to precharge the external capacitor 104 to the first voltage. Alternatively, the fourth switch S4 can be closed to precharge the external capacitor 104 to the first voltage using the voltage source V1 of the precharging module 106.

[0061] In some optional embodiments of the present invention, continue to refer to Figure 4 The switch module 103 is also used to connect the first end and the third end when the external capacitor 104 is pre-charged; the detection module 105 is also used to control the switch module to connect the first end and the third end when the external capacitor is pre-charged to a first voltage; wherein the first voltage is less than the reference voltage signal.

[0062] The control unit 1052 can be used to control the reference voltage signal Vref at the first input terminal of the voltage detection unit 1051. When charging the external capacitor 104, the control unit 1052 can change the reference voltage signal Vref to the first voltage. In this case, the first input terminal of the voltage detection unit 1051 is the first voltage. Specifically, the switch module 103 is controlled to connect the first terminal and the third terminal, that is, the first switch S1 and the third switch S3 are closed, so that the external capacitor 104 can be charged through the power supply terminal Vc. The voltage detection unit 1051 monitors the charging voltage of the external capacitor 104 in real time. When the voltage of the external capacitor 104 is greater than or equal to the first voltage, the voltage detection unit 1051 outputs a pre-charge end control signal to open the first switch S1 and the third switch S3.

[0063] Figure 5 is a circuit diagram of a touch detection device provided by an embodiment of the present invention, such as Figure 5 As shown, Cf is a parasitic capacitor. When a finger touches the touch electrode 101, the parasitic capacitor Cf is connected in parallel with the parasitic capacitor of the touch electrode 101, and the capacitance on the channel increases. The difference in the number of times the touch electrode 101 is charged to the external capacitor 104 is determined based on whether or not a finger touches the touch electrode 101, thereby achieving touch detection. In the first step, the channel selection module 102 selects the touch electrode 101 in sequence; in the second step, the first switch S1 and the third switch S3 are disconnected, and the second switch S2 is closed to discharge the touch electrode 101; in the third step, the second switch S2 and the third switch S3 are disconnected, and the first switch S1 is closed to charge the touch electrode 101; in the fourth step, the first switch S1 and the second switch S2 are disconnected, and the third switch S3 is closed, and the touch electrode 101 charges the external capacitor 104; in the fifth step, the third and fourth steps are repeated. After the external capacitor 104 is charged to the reference voltage signal Vref, the output level of the voltage detection unit 1051 is reversed. In the sixth step, after the voltage detection unit 1051 is reversed, the closing times of the third switch S3 are counted, which is the charging times of the touch electrode 101 to the external capacitor 104 .

[0064] Figure 6 is a flow chart of a touch detection method provided by an embodiment of the present invention, which can be implemented by using the touch detection device described in any of the above embodiments. Figure 5 and Figure 6 , the method comprising:

[0065] S201, the first step, selecting an input terminal and an output terminal of the channel selection module 102;

[0066] The input end of the channel selection module 102 is connected to the second ends of at least two touch electrodes 101 . The channel selection module 102 can select one touch electrode 101 from different touch electrodes 101 and connect it to the output end.

[0067] S202, step 2, controlling the switch module 103 to connect the common terminal and the second terminal to discharge the touch electrode 101;

[0068] The common terminal of the switch module 103 is connected to the output terminal of the channel selection module 102, and the second terminal of the switch module 103 is connected to ground. After the switch module 103 is controlled to connect the common terminal and the second terminal, the touch electrode 101 selected by the channel selection module 102 is connected to ground, and the charge on the touch electrode 101 is discharged to the ground. After the touch electrode 101 is discharged, the common terminal and the second terminal of the switch module 103 are disconnected.

[0069] S203, step 3, controlling the switch module 103 to connect the third terminal and the second terminal to discharge the external capacitor 104;

[0070] The third terminal of the switch module 103 is connected to the first terminal of the external capacitor 104. After the third terminal and the second terminal of the switch module 103 are connected, the external capacitor 104 is connected to the ground, and the charge on the external capacitor 104 is discharged to the ground. After the external capacitor 104 is discharged, the third terminal and the second terminal of the switch module 103 are disconnected.

[0071] S204, step 4, controlling the switch module 103 to connect the common terminal and the first terminal to charge the touch electrode 101;

[0072] The common terminal of the switch module 103 is connected to the output terminal of the channel selection module 102, and the first terminal of the switch module 103 is connected to the power supply terminal Vc. By controlling the switch module 103 to connect the common terminal and the first terminal, the touch electrodes 101 selected by the channel selection module 102 are connected to the power supply terminal Vc, forming a charging circuit. After the touch electrodes 101 are fully charged, the common terminal and the first terminal of the switch module 103 are disconnected.

[0073] S205, step 5, controlling the switch module 103 to connect the common terminal and the third terminal to charge the external capacitor 104;

[0074] The third terminal of the switch module 103 is connected to the first terminal of the external capacitor 104. The switch module 103 is controlled to connect the common terminal and the third terminal, thereby connecting the touch electrode 101 selected by the channel selection module 102 to the external capacitor 104. The charge of the parasitic capacitance of the touch electrode 101 is transferred to the external capacitor 104 to charge the external capacitor 104. After the external capacitor 104 is fully charged, the common terminal and the first terminal of the switch module 103 are disconnected.

[0075] S206, step 6, repeating steps 4 and 5 to charge the external capacitor 104 to the reference voltage signal Vref;

[0076] The charging process of the touch electrode 101 and the charging process of the touch electrode 101 to the external capacitor 104 is repeated until the external capacitor 104 is charged to the reference voltage signal Vref. When the voltage of the external capacitor 104 is greater than or equal to the reference voltage signal Vref, the voltage detection unit 1051 outputs a charging end control signal to stop the touch electrode 101 from charging the external capacitor 104.

[0077] S207, step seven, performing touch detection according to the number of times the switch module 103 connects the common terminal and the third terminal.

[0078] If the touch electrode 101 is not touched, the charge transferred each time is small, requiring more charging cycles for the external capacitor 104 to reach the reference voltage signal Vref. If touched, the charge transferred each time increases, requiring fewer charging cycles. Touch detection can be performed by monitoring the number of times the switch module 103 connects the common terminal to the third terminal, i.e., the number of times the touch electrode 101 charges the external capacitor 104.

[0079] For example, assume that the parasitic capacitance of the touch electrode 101 is 10Pf, the external capacitor 104 is 10Nf, the voltage of the power supply terminal is 3V, the voltage of the reference voltage signal Vref is 1.5V, and the parasitic capacitance generated when a finger touches is 1Nf. When there is no finger touch, it is calculated that the touch electrode 101 needs to charge and discharge the external capacitor 104 694 times. When there is a finger touch, the touch electrode 101 needs to charge and discharge the external capacitor 104 631 times, and the impact of the finger touch is 63 times. In this process, the charge and discharge waveform of the touch electrode 101 is as follows: Figure 7 As shown in the figure, the actual number of charge and discharge times is related to the reference voltage signal Vref, the power supply terminal Vc, the parasitic capacitance of the touch electrode 101, and the capacitance of the external capacitor 104. During the charge and discharge process, as the voltage of the external capacitor 104 gradually increases, the starting voltage of the touch electrode 101 also gradually increases. According to the charge formula Q=CU, the amount of charge discharged each time decreases as the voltage difference decreases. At this time, the voltage rise of the external capacitor 104 after each charge transfer also gradually decreases. The waveform of the external capacitor 104 is shown in the figure. Figure 8 As shown in the figure, the influence of the finger decreases sharply with the increase of the cover thickness. Under the condition of continuous charging and discharging, the amount of charge and discharge each time is less than the previous one. Therefore, in order to clearly identify the influence of the finger, it is necessary to charge to a larger voltage so that the number of discharges can change significantly. It requires many times of charging and discharging. To set a higher voltage, the reference voltage signal Vref is set to half the voltage of the power supply terminal Vc, which also requires charging 694 times. Considering that it takes time to balance the two capacitors, it has been tested that the charging time under the above parameter conditions shall not be less than 62.5Ns, that is, the charging and discharging speed needs to be controlled below 8Mhz.

[0080] Figure 9 is a flowchart of another touch detection method provided by an embodiment of the present invention, refer to Figure 5 、 Figure 6 and Figure 9 The touch detection device further includes a pre-charge module 106, which is connected to the external capacitor 104. Before S203 (the fifth step), in which the switch module is controlled to connect the common terminal and the first terminal to charge the touch electrode, S303 (the fifth step), in which the pre-charge module is controlled to connect to the external capacitor, is added to pre-charge the external capacitor to a first voltage; wherein the first voltage is less than the reference voltage signal. The method includes:

[0081] S301, the first step, selecting an input terminal and an output terminal of the channel selection module 102;

[0082] S302, step 2, controlling the switch module 103 to connect the common terminal and the second terminal to discharge the touch electrode 101;

[0083] S303, step 3, controlling the switch module 103 to connect the third terminal and the second terminal to discharge the external capacitor 104;

[0084] S304, step 4, controlling the switch module 103 to connect the common terminal and the first terminal to charge the touch electrode 101;

[0085] S305 , step 5, controlling the pre-charge module 106 to communicate with the external capacitor 104 , and pre-charging the external capacitor 104 to a first voltage; wherein the first voltage is lower than the reference voltage signal.

[0086] Among them, such as Figure 7 As shown, during touch detection, the capacitance of the parasitic capacitor Cf is relatively small, and its impact on the number of charge and discharge cycles is only apparent in the latter half of the final charge and discharge cycle. The previous hundreds of charges took too much time, and precharging the external capacitor 104 to the first voltage can speed up the recognition of small capacitance changes, shorten the charging time, and thus reduce the average power consumption overall. The first voltage is less than the reference voltage signal Vref, and the reference voltage signal Vref is less than the power supply terminal Vc. Specifically, the power module can reuse the voltage source to provide the first voltage to the power supply terminal Vc, control the switch module 103 to connect the first terminal and the third terminal, that is, close the first switch S1 and the third switch S3, and use the first voltage provided by the power supply terminal Vc to charge the external capacitor 104. After the external capacitor 104 is charged to the first voltage, the first switch S1 and the third switch S3 are disconnected. . It is also possible to precharge the external capacitor 104 to the first voltage using the voltage source V1 of the precharge module 106 by closing the fourth switch S4. The power module may also be used to provide a first voltage to the power supply terminal Vc, close the first switch S1 and the third switch S3, and use the power supply terminal Vc to charge the external capacitor 104 to the first voltage.

[0087] S306, step 6, controlling the switch module 103 to connect the common terminal and the third terminal to charge the external capacitor 104;

[0088] S307, step 7, repeat steps 4 and 6 to charge the external capacitor 104 to the reference voltage signal Vref;

[0089] S308, step eight, performing touch detection according to the number of times the switch module 103 connects the common terminal and the third terminal.

[0090] The technical solution of the embodiment of the present invention reduces the amount of charge used during actual touch detection by precharging the external capacitor 101 to a first voltage, compared to the previous discharge of the external capacitor to 0V. This reduction in charge can reduce the impact of IO discharge, allowing it to charge to the set voltage point more quickly, shortening the touch detection cycle time and reducing the average current, saving space and data processing time, and further reducing average power consumption. Lower power consumption can also reduce external radiation, significantly improving radiated emission (RE) and conducted emission (CE) testing.

[0091] In some optional embodiments of the present invention, before the fifth step, the method further includes:

[0092] The third end of the control switch module 103 is connected to the first end to pre-charge the external capacitor 104 to the first voltage.

[0093] The control unit 1052 can change the reference voltage signal Vref at the first input terminal of the voltage detection unit 1051 to a first voltage. The power supply terminal Vc can be used to pre-charge the external capacitor 104 to the first voltage. The first voltage is less than the reference voltage signal Vref, and the reference voltage signal Vref is less than the power supply terminal Vc. The first switch S1 and the third switch S3 are closed to charge the external capacitor 104. The voltage detection unit 1051 monitors the charging voltage of the external capacitor 104 in real time. When the external capacitor 104 is charged to the first voltage, the voltage detection unit 1051 outputs a pre-charging end control signal to disconnect the first switch S1 and the third switch S3. At this time, the external capacitor 104 has been charged to the first voltage.

[0094] In some optional embodiments of the present invention, continue to refer to Figure 5 and Figure 8 , after step 7, also includes:

[0095] The external capacitor 104 is discharged to a first voltage.

[0096] In particular, the control unit 1052 can change the reference voltage signal Vref at the first input terminal of the voltage detection unit 1051 to a first voltage, and can control the third terminal of the switch module 103 to connect to the first terminal, that is, close the first switch S1 and the third switch S3, and discharge the external capacitor 104. When the external capacitor 104 is discharged to the first voltage, the voltage detection unit 1051 outputs a discharge end control signal to disconnect the first switch S1 and the third switch S3. At this time, the external capacitor 104 has been discharged to the first voltage. The external capacitor 104 can also be discharged through the pre-charge module 106, closing the fourth switch S4, and discharging the external capacitor 104 to the first voltage through the voltage source V1. The power supply module can also reuse the voltage source to provide the first voltage to the power supply terminal Vc, control the switch module 103 to connect the first terminal and the third terminal, that is, close the first switch S1 and the third switch S3, and discharge the external capacitor 104 using the first voltage provided by the power supply terminal Vc. After the external capacitor 104 is discharged to the first voltage, the first switch S1 and the third switch S3 are disconnected.

[0097] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0098] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A touch detection device, characterized in that: include: At least two touch electrodes, a channel selection module, a switch module, an external capacitor and a detection module; The first end of each touch electrode and the second end of the external capacitor are grounded, the second end of each touch electrode is correspondingly connected to an input end of the channel selection module, the output end of the channel selection module is connected to the common end of the switch module, the first end of the switch module is connected to the power end, the second end of the switch module is connected to the ground, and the third end of the switch module is connected to the first end of the external capacitor. The switch module is configured to connect the common end and the second end of the switch module when the touch electrode is discharging, connect the third end and the second end of the switch module when the external capacitor is discharging, connect the common end and the first end of the switch module when the touch electrode is charging, and connect the common end and the third end of the switch module when the touch electrode is charging the external capacitor. The channel selection module is configured to select any input end and output end. The input end of the detection module is connected to the first end of the external capacitor. The detection module is configured to perform touch detection based on the number of times the switch module connects the common end and the third end when the external capacitor is charged to a reference voltage signal.

2. The touch detection device according to claim 1, wherein: The detection module includes a voltage detection unit and a control unit. The first input end of the voltage detection unit is connected to the reference voltage signal end, the second input end of the voltage detection unit is connected to the first end of the external capacitor, the input end of the control unit is connected to the output end of the voltage detection unit, and the output end of the control unit is connected to the first input end of the voltage detection unit. The voltage detection unit is used to output a charging termination control signal when the charging voltage of the external capacitor is greater than or equal to the reference voltage signal; the control unit is used to perform touch detection based on the number of times the switch module connects the common end and the third end when receiving the charging termination control signal.

3. The touch detection device according to claim 1, wherein: The switch module includes a first switch, a second switch, and a third switch. The first end of the first switch is connected to the power supply end, the second end of the first switch is connected to the first end of the second switch, the first end of the third switch, and the output end of the channel selection module, the second end of the second switch is connected to the ground, and the second end of the third switch is connected to the first end of the external capacitor.

4. The touch detection device according to any one of claims 1 to 3, characterized in that: It also includes a pre-charge module, which is connected to the external capacitor and is used to pre-charge the external capacitor to a first voltage; wherein the first voltage is less than the reference voltage signal.

5. The touch detection device according to claim 4, characterized in that: The pre-charge module includes a voltage source and a fourth switch; The voltage source is connected to the first end of the fourth switch, and the second end of the fourth switch is connected to the first end of the external capacitor; or, The touch detection device also includes a power supply module, which is used to provide a power supply voltage to the power supply end in a first mode. The power supply module is multiplexed as the voltage source, which is used to provide the first voltage to the power supply end in a second mode; the first switch and the third switch are multiplexed as the fourth switch.

6. The touch detection device according to any one of claims 1 to 3, characterized in that: The switch module is also used to connect the first end and the third end when the external capacitor is pre-charged; the detection module is also used to control the switch module to connect the first end and the third end when the external capacitor is pre-charged to a first voltage; wherein, the first voltage is less than the reference voltage signal.

7. A touch detection method, characterized in that: The touch detection method is implemented using the touch detection device according to any one of claims 1 to 6, and includes: The first step is to select an input terminal and an output terminal of the channel selection module; Step 2: Control the switch module to connect the common terminal and the second terminal to discharge the touch electrode; Step 3: Control the switch module to connect the third terminal to the second terminal to discharge the external capacitor; Step 4: Control the switch module to connect the common terminal and the first terminal to charge the touch electrode; Step 5: Control the switch module to connect the common terminal and the third terminal to charge the external capacitor; Step 6: Repeat the fourth and fifth steps to charge the external capacitor to a reference voltage signal; Step 7: Perform touch detection according to the number of times the switch module connects the common terminal and the third terminal.

8. The touch detection method according to claim 7, wherein: The touch detection device further includes a pre-charging module connected to the external capacitor, and before the fifth step, further includes: The pre-charge module is controlled to be connected to the external capacitor to pre-charge the external capacitor to a first voltage; wherein the first voltage is less than a reference voltage signal.

9. The touch detection method according to claim 7, wherein: Before step 5, it also includes: The third end of the switch module is controlled to be connected to the first end, so as to pre-charge the external capacitor to a first voltage.

10. The touch detection method according to claim 8 or 9, characterized in that: After step 7, it also includes: The external capacitor is discharged to a first voltage.

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