A touch control circuit

Abstract

The present invention relates to a touch control circuit, including a control module, a capacitive sensing module and a touch module; the control module provides a reference voltage to the capacitive sensing module, sends a square wave signal of a stable frequency, collects the voltage change of the capacitive sensing module, and sends an action instruction to the downstream circuit after processing; the frequency of the square wave signal can be preset according to the circuit requirements; the capacitive sensing module includes a first resistor, a second resistor, a capacitor, a first switch, a second switch and an analog-to-digital converter, which is used to detect whether the touch module is in contact with a human body; the touch module includes one or more touch channels for direct human contact and air touch. The present invention has the advantages of simple circuit implementation, small area, precise touch control and simple touch method.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to a touch control circuit. Background Art

[0002] Touch technology can be seen everywhere in our daily life, such as touch-screen mobile phones, small household appliances operated by touch screens, and touch-screen switches. Touch control is mainly achieved by resistive touch and capacitive touch technologies. Among them, capacitive touch is widely used due to its fast response and low cost. With the development of technology, people's demand for capacitive touch circuits has also changed, requiring further simplification of circuits and reduction of circuit area on the basis of accurate touch control. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a touch control circuit, including a control module, a capacitive sensing module and a touch module;

[0004] The control module provides a reference voltage and a square wave signal with a stable output frequency to the capacitive sensing module, collects the voltage change of the capacitive sensing module, and sends an action instruction to the downstream circuit after processing; the frequency of the square wave signal can be pre-set according to the circuit requirements, for example, by setting the reference voltage to control the high and low levels of the square wave signal;

[0005] A capacitive sensing module, comprising a first resistor, a second resistor, a capacitor, a first switch, a second switch and an analog-to-digital converter, for detecting whether the touch module is directly contacted by a human body or contacted through air;

[0006] The touch module includes one or more touch channels for direct human body contact and air touch.

[0007] Further, the capacitive sensing module includes a first resistor, a second resistor, a capacitor, a first switch, a second switch and an analog-to-digital converter;

[0008] The first resistor and the second resistor are connected in series; the positive electrode of the first switch is connected between the first resistor and the second resistor;

[0009] The positive electrode of the second switch is connected between the first resistor and the second resistor;

[0010] The capacitor is connected to the opposite end of the second resistor connected to the first resistor, and the opposite end of the capacitor connected to the second resistor is grounded;

[0011] The analog-to-digital converter is connected between the second resistor and the capacitor, and is used to collect the voltage of the capacitor.

[0012] Furthermore, the resistance values ​​of the first resistor and the second resistor can be adjusted according to specific needs; and the capacitor is a low-temperature drift capacitor.

[0013] Furthermore, the output end of the control module is connected to a first resistor and a second resistor connected in series to achieve power supply and communication with the capacitive sensing module; and the touch module is connected between the first resistor and the second resistor connected in series.

[0014] Furthermore, the control module may output a frequency-stable square wave signal to the capacitive sensing module by using a comparator, an oscillation circuit or other circuits that can output a square wave signal.

[0015] Furthermore, the touch channel includes a multi-way selection switch, a pull-up resistor and a human body contact point.

[0016] Furthermore, the plurality of touch channels are connected in parallel; the input end of the multi-way selection switch is connected between the first resistor and the second resistor;

[0017] The first output end of the multi-way selection switch is connected to the pull-up resistor; the second output end of the multi-way selection switch is connected to the human body contact point.

[0018] Furthermore, the touch module is connected to at most one touch channel at the same time.

[0019] Furthermore, the present invention also provides a specific working method of the above touch control circuit:

[0020] The control module supplies power to the capacitive sensing module and the touch module, and continuously sends a square wave signal to the capacitive sensing module until the capacitive sensing module;

[0021] When the control module outputs a high level, the first switch is turned off, the second switch is turned on, and the current passes through the first resistor and the second switch to charge the capacitor; when the control module outputs a low level, the first switch is turned on, the second switch is turned off, the capacitor C is discharged, and the current flows to the control module through the second resistor and the first switch until a stable voltage is formed at the capacitor C;

[0022] When the touch module is not in contact, the multi-way selection switch of the touch channel is connected to the first output terminal;

[0023] When an object touches the touch module, the multi-way selection switch of the touch channel is connected to the second output terminal; the discharge speed of the capacitor is accelerated and the charging speed is slowed down, and the voltage at the capacitor C collected by the analog-to-digital converter decreases; the control module monitors the voltage data collected by the analog-to-digital converter, and after processing, sends corresponding action instructions to the downstream circuit to realize touch control;

[0024] Specifically, when only one touch channel of the touch module is touched by an object, the multi-way selection switch of the touch channel is connected to the second output terminal, the discharge speed of the capacitor is accelerated, the charging speed is slowed down, the voltage of the capacitor collected by the analog-to-digital converter decreases, and the control module monitors the voltage data collected by the analog-to-digital converter, and after processing, sends a corresponding action instruction to the downstream circuit to realize touch control;

[0025] When two or more touch channels of the touch module are touched by objects at the same time, the second output end of the multi-way selection switch of one of the touch channels is first connected, and the control module monitors and processes the voltage change data caused by the touch channel being turned on, and sends corresponding action instructions to the downstream circuit. After the touch control is completed, the multi-way selection switch of the touch channel is pulled up to the first output end, and the multi-way selection switch of the next touch channel is connected to the second output end, and the touch control of the touch channels is completed in sequence.

[0026] Compared with the prior art, the beneficial effects of the present invention include:

[0027] (1) Touch sensing can be achieved through two resistors, two switches, a capacitor and an analog-to-digital converter. The circuit is simple to implement and takes up a small area.

[0028] (2) The frequency of the square wave signal output by the control circuit is stable, and the use of low-temperature drift capacitors reduces the error of the circuit itself, making touch control more accurate and the touch method simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A module schematic diagram of a touch control circuit provided by the present invention.

[0030] Figure 2 A circuit diagram of a touch control circuit provided in Embodiment 1 of the present invention.

[0031] Figure 3 A circuit diagram of a touch control circuit provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments.

[0033] Embodiment 1 provides a touch control circuit, such as Figure 1 As shown, the touch control circuit includes a control module, a capacitive sensing module and a touch module; the control module provides a reference voltage VREF to the touch control circuit through a power supply and a communication interface, and outputs a preset frequency-stable square wave signal, and sends an action instruction to the downstream circuit according to the voltage change of the capacitive sensing module.

[0034] like Figure 2 As shown, the capacitive sensing module includes a first resistor R1, a second resistor R2, a capacitor C, a first switch S1, a second switch S2 and an analog-to-digital converter ADC, which is used to detect whether the touch module is touched by a human body; the touch module includes a touch channel, the touch channel includes a multi-way selection switch S3, a pull-up resistor R3 and a human body contact point T, the first output end 2 of the multi-way selection switch is connected to the pull-up resistor, and the other end of the pull-up resistor R3 is connected to the power supply VCC; the second output end 3 of the multi-way selection switch is connected to the human body contact point for direct human body contact.

[0035] The first resistor R1 and the second resistor R2 are connected in series; the positive electrode of the first switch S1 is connected between the first resistor R1 and the second resistor R2;

[0036] The positive electrode of the second switch S2 is connected between the first resistor R1 and the second resistor R2;

[0037] The capacitor C is connected to the opposite end of the second resistor R2 connected to the first resistor R1, and the opposite end of the capacitor C connected to the second resistor R2 is grounded;

[0038] The analog-to-digital converter ADC is connected between the second resistor R2 and the capacitor C, and is used for collecting the voltage of the capacitor.

[0039] The control module is connected to the first resistor and the second resistor in series through power supply and communication interface; the touch channel of the touch module is connected between the first resistor and the second resistor in series through the third switch S3; when there is no human body contact, the third switch S3 connects to the first output end.

[0040] In this embodiment, the operating voltage of the entire circuit is 5V, the output frequency of the control module is set to 200kHz, 50% duty cycle, the first resistor R1 and the second resistor R2 have the same resistance value, both of which are 100KOhm, and the capacitor C uses a low temperature drift capacitor.

[0041] When the touch module is not in contact, the multi-way selection switch S3 of the touch channel is connected to the first output terminal 2; when the control module outputs a high level, the first switch S1 is disconnected, the second switch S2 is connected, and the current passes through the first resistor R1 and the second switch S2 to charge the capacitor C; when the control module outputs a low level, the first switch S1 is connected, the second switch S2 is disconnected, the capacitor C is discharged, and the current flows to the control module through the second resistor R2 and the first switch S1; until a stable voltage is formed at the capacitor C;

[0042] When an object touches the touch module, the multi-way selection switch S3 of the touch channel is connected to the second output terminal 3; the discharge speed of the capacitor C is accelerated and the charging speed is slowed down, and the voltage collected by the analog-to-digital converter ADC decreases;

[0043] The control module monitors the voltage data of the analog-to-digital converter and, after processing, sends corresponding action instructions to the downstream circuit to achieve touch control.

[0044] Embodiment 2 provides a touch control circuit, including a control module, a capacitive sensing module and a touch module; Figure 3 As shown, the control module is used to provide a reference voltage VREF and a square wave signal with a stable output frequency to the touch control circuit, and send an action instruction to the downstream circuit according to the voltage change of the capacitive sensing module;

[0045] The capacitive sensing module includes a first resistor R1, a second resistor R2, a capacitor C, a first switch S1, a second switch S2 and an analog-to-digital converter ADC, which is used to detect whether the touch module is touched by a human body; the touch module includes 8 parallel touch channels, namely a first touch channel P1, a second touch channel P2, a third touch channel P3, a fourth touch channel P4, a fifth touch channel P5, a sixth touch channel P6, a seventh touch channel P7 and an eighth touch channel P8; each touch channel includes a multi-way selection switch, a pull-up resistor and a direct human body contact point;

[0046] Specifically, the first touch channel P1 includes a third switch S3, a third resistor R3 and a first contact point T1;

[0047] The second contact channel P2 includes a fourth switch S4, a fourth resistor R4 and a second contact point T2;

[0048] The third contact channel P3 includes a fifth switch S5, a fifth resistor R5 and a third contact point T3;

[0049] The fourth contact channel P4 includes a sixth switch S6, a sixth resistor R6 and a fourth contact point T4;

[0050] The fifth contact channel P5 includes a seventh switch S7, a seventh resistor R7 and a fifth contact point T5;

[0051] The sixth contact channel P6 includes an eighth switch S8, an eighth resistor R8 and a sixth contact point T6;

[0052] The seventh contact channel P7 includes a ninth switch S9, a ninth resistor R9 and a seventh contact point T7;

[0053] The eighth contact channel P8 includes a tenth switch S10, a tenth resistor R10 and an eighth contact point T8.

[0054] The first resistor R1 and the second resistor R2 are connected in series; the positive electrode of the first switch S1 is connected between the first resistor R1 and the second resistor R2;

[0055] The positive electrode of the second switch S2 is connected between the first resistor R1 and the second resistor R2;

[0056] The capacitor C is connected to the opposite end of the second resistor R2 connected to the first resistor R1, and the opposite end of the capacitor C connected to the second resistor R2 is grounded;

[0057] The analog-to-digital converter ADC is connected between the second resistor R2 and the capacitor C, and is used to collect the voltage of the capacitor C;

[0058] The power supply and communication interface of the control module are connected to the first resistor and the second resistor in series;

[0059] In the touch module, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, the ninth switch S9, and the tenth switch S10 are connected in parallel, and the input end 1 of the third switch S3 to the tenth switch S10 is connected between the first resistor R1 and the second resistor R2 connected in series; the first output end 2 of the third switch S3 to the tenth switch S10 is respectively connected to the third resistor R3 to the tenth resistor R10; the other end of the third resistor R3 to the tenth resistor R10 is connected to the power supply VCC; the second output end 3 of the third switch S3 to the tenth switch S10 is respectively connected to the first contact point T1 to the eighth contact point T8.

[0060] In this embodiment, the operating voltage of the entire circuit is 3V, the signal frequency output by the control module is set to 500kHz, 50% duty cycle, the first resistor R1 and the second resistor R2 have the same resistance value, both of which are 300KOhm, and the capacitor C uses a low temperature drift capacitor.

[0061] When the control module outputs a high level, the first switch S1 is turned off, the second switch S2 is turned on, and the current passes through the first resistor R1 and the second switch S2 to charge the capacitor C; when the control module outputs a low level, the first switch S1 is turned on, the second switch S2 is turned off, the capacitor C is discharged, and the current flows to the control module through the second resistor R2 and the first switch S1; until a stable voltage is formed at the capacitor C;

[0062] When the touch module is not in contact, the third switch S3 to the tenth switch S10 connect the first output terminal 2, and the circuit operates according to the signal frequency output by the oscillation circuit. At this time, the voltage at the analog-to-digital converter ADC is stable;

[0063] When only the first contact point T1 corresponding to the first touch channel P1 of the touch module is touched by an object, the third switch S3 of the first touch channel P1 is connected to the second output terminal 3; the discharge speed of the capacitor C is accelerated and the charging speed is slowed down, and the voltage collected by the analog-to-digital converter ADC decreases; the control module monitors the voltage data collected by the analog-to-digital converter ADC, and after processing, sends corresponding action instructions to the downstream circuit to realize touch control.

[0064] When the third touch point T3, the fifth touch point T5 and the eighth touch point T8 of the touch module are touched by objects at the same time, the third touch channel P3, the fifth touch channel P5 and the eighth touch channel P8 are connected in sequence.

[0065] Specifically, the third touch channel P3 is first turned on, and the fifth switch S5 is turned on the second output terminal. After the control module monitors and processes the voltage change data caused by the third touch channel P3 being turned on, and sends a corresponding action instruction to the downstream circuit, after the touch control is completed, the fifth switch S5 is pulled up to the first output terminal 2 to disconnect the third touch channel P3;

[0066] Next, the fifth touch channel P5 is turned on, and the seventh switch S7 is turned on the second output terminal 3. After the control module monitors and processes the voltage change data caused by the fifth touch channel P5 being turned on, and sends a corresponding action instruction to the downstream circuit, after the touch control is completed, the seventh switch S7 is pulled up to the first output terminal 2 to disconnect the fifth touch channel P5;

[0067] Next, the eighth touch channel P8 is turned on, the tenth switch S10 is turned on the second output terminal 3, the control module monitors and processes the voltage change data caused by the eighth touch channel P8 being turned on, and sends corresponding action instructions to the downstream circuit to complete the touch control.

[0068] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A touch control circuit, characterized in that: It includes a control module, a capacitive sensing module and a touch module; The control module provides a reference voltage to the capacitive sensing module, sends a square wave signal with a stable frequency, collects the voltage change of the capacitive sensing module, and after processing, sends an action instruction to the downstream circuit; the frequency of the square wave signal can be pre-set according to the circuit requirements; A capacitive sensing module, comprising a first resistor, a second resistor, a capacitor, a first switch, a second switch and an analog-to-digital converter, for detecting whether a touch module is touched by a human body; in the capacitive sensing module, the first resistor and the second resistor are connected in series; the positive electrode of the first switch is connected between the first resistor and the second resistor; the positive electrode of the second switch is connected between the first resistor and the second resistor; the capacitor is connected to the opposite end of the second resistor connected to the first resistor, and the opposite end of the capacitor connected to the second resistor is grounded; the analog-to-digital converter is connected between the second resistor and the capacitor, for collecting the voltage of the capacitor; The touch module includes one or more touch channels for direct human body contact and air touch.

2. The touch control circuit according to claim 1, characterized in that: The resistance values ​​of the first resistor and the second resistor can be adjusted according to specific needs; the capacitor is a low temperature drift capacitor.

3. The touch control circuit according to claim 1, characterized in that: The output end of the control module is connected to a first resistor and a second resistor connected in series; and the touch module is connected between the first resistor and the second resistor connected in series.

4. The touch control circuit according to claim 1, characterized in that: The control module can output a frequency-adjustable square wave signal to the capacitance sensing circuit by using a comparator, an oscillation circuit or other circuits that can output a square wave signal.

5. The touch control circuit according to claim 1, characterized in that: The touch channel includes a multi-way selection switch, a pull-up resistor and a human body contact point.

6. The touch control circuit according to claim 5, characterized in that: The multiple touch channels are connected in parallel; the input end of the multi-way selection switch is connected between the first resistor and the second resistor; The first output terminal of the multi-way selection switch is connected to the pull-up resistor; The second output end of the multi-way selection switch is connected to the human body contact point.

7. The touch control circuit according to claim 6, characterized in that: The touch module is connected to at most one touch channel at the same time.

8. The touch control circuit according to any one of claims 1 to 7, characterized in that: The specific working method of the touch control circuit is: The control module supplies power to the capacitive sensing module and the touch module, and according to a pre-set configuration, continuously sends a square wave signal with a stable frequency to the capacitive sensing module; When the control module outputs a high level, the first switch is turned off, the second switch is turned on, and the current passes through the first resistor and the second switch to charge the capacitor; when the control module outputs a low level, the first switch is turned on, the second switch is turned off, the capacitor C is discharged, and the current flows to the control module through the second resistor and the first switch; Until a stable voltage is formed at the capacitor C; When the touch module is not in contact, the multi-way selection switch of the touch channel is connected to the first output terminal; When the touch module is in contact, the multi-way selection switch of the touch channel is connected to the second output terminal; the discharge speed of the capacitor is accelerated and the charging speed is slowed down, and the voltage at the capacitor C collected by the analog-to-digital converter decreases; The control module monitors the voltage data collected by the analog-to-digital converter, and after processing, sends corresponding action instructions to the downstream circuit to achieve touch control.

Images