一种触摸检测电路和电子设备

Abstract

本实用新型实施例提供了一种触摸检测电路和电子设备，包括触摸传感器、开关组件、第二电容、第三电容和差分放大器，触摸传感器包括第一电容，开关组件用于依次导通电源与第二电容之间的通路、第一电容与第二电容之间的通路、第一电容与电源之间的通路，第一电容与第三电容之间的通路，通过对第一电容进行两次电荷转移分配，再通过差分放大器对第二电容和第三电容的电压进行差分放大，能够实现在手指按压下检测到差分放大器的输出电压趋近于与手指按压下的电容呈线性相关，能够减小触摸传感器的寄生电容对触摸检测的影响，并且差分放大其进行差分放大使得输出电压范围较大，利于根据差分放大器的输出电压进行触摸检测，从而提高触摸检测的准确性和灵敏度。

Claims

1. A touch detection circuit, characterized by, The touch detection circuit includes a touch sensor, a switching assembly, a second capacitor, a third capacitor, and a differential amplifier; the touch sensor includes a first capacitor; The switching assembly is connected to the first capacitor, the power supply, the second capacitor, and the third capacitor respectively; the switching assembly is used to sequentially open the path between the power supply and the second capacitor, the path between the first capacitor and the second capacitor, the path between the first capacitor and the power supply, and the path between the first capacitor and the third capacitor. When the path between the power source and the second capacitor is open, the power source charges the second capacitor; when the path between the first capacitor and the second capacitor is open, the charge of the second capacitor is transferred to the first capacitor; when the path between the first capacitor and the power source is open, the power source charges the first capacitor; when the path between the first capacitor and the third capacitor is open, the charge of the first capacitor is transferred to the third capacitor. The first input terminal of the differential amplifier is connected to the second capacitor, and the second input terminal is connected to the third capacitor, for outputting a detection voltage based on the voltage difference between the second capacitor and the third capacitor; the detection voltage is used to determine whether the touch sensor has been touched.

2. The touch detection circuit of claim 1, wherein, The switching assembly includes a first switch disposed between the power source and the second capacitor; when the first switch is closed, the path between the power source and the second capacitor is opened.

3. The touch detection circuit of claim 2, wherein, The switching assembly includes a second switch, one end of which is located between one end of the second capacitor and the first switch, and the other end is connected to one end of the first capacitor. The other end of the first capacitor is grounded, and the other end of the second capacitor is grounded. When the first switch is open and the second switch is closed, the path between the first capacitor and the second capacitor is open.

4. The touch detection circuit of claim 3, wherein, The switching assembly includes a third switch, one end of which is connected to the power source, and the other end is located between the first capacitor and the second switch; when the second switch is open and the third switch is closed, the path between the first capacitor and the power source is connected.

5. The touch detection circuit of claim 4, wherein, The switching assembly includes a fourth switch, one end of which is located between the first capacitor and the third switch, and the other end is connected to the third capacitor, one end of which is grounded; when the third switch is open and the fourth switch is closed, the path between the first capacitor and the third capacitor is open.

6. The touch detection circuit of claim 1, wherein, Before the switching assembly connects the first capacitor and the second capacitor, it is also used to connect the first capacitor and the ground terminal to discharge the first capacitor until the charge is zero.

7. The touch detection circuit according to claim 1, characterized in that, Before the switching assembly connects the first capacitor and the third capacitor, it is also used to connect the third capacitor and the ground terminal, so that the third capacitor discharges until the charge is zero.

8. The touch detection circuit of claim 6, wherein, The switching assembly includes a fifth switch, one end of which is grounded and the other end is located between the first capacitor and the first switch; when the fifth switch is closed, the path between the first capacitor and the grounded end is connected.

9. The touch detection circuit of claim 7, wherein, The switching assembly includes a sixth switch, one end of which is grounded and the other end is located between the third capacitor and the fourth switch; when the sixth switch is closed, the path between the third capacitor and the grounded terminal is connected.

10. The touch detection circuit of claim 1, wherein, The circuit also includes a first voltage follower and a second voltage follower; The first input terminal of the first voltage follower is connected to the second capacitor, the second input terminal is connected to the output terminal, and the output terminal is connected to the first input terminal of the differential amplifier, for transmitting the output voltage of the second capacitor to the first input terminal of the differential amplifier; The first input terminal of the second voltage follower is connected to the third capacitor, the second input terminal is connected to the output terminal, and the output terminal is connected to the second input terminal of the differential amplifier, for transmitting the output voltage of the third capacitor to the second input terminal of the differential amplifier.

11. The touch detection circuit of claim 10, wherein, The differential amplifier includes a first resistor, a second resistor, a third resistor, a fourth resistor, and an operational amplifier; One end of the first resistor is connected to the output terminal of the first voltage follower, and the other end is connected to the fourth resistor and the first input terminal of the operational amplifier, respectively. One end of the second resistor is connected to the output terminal of the second voltage follower, and the other end is connected to the third resistor and the second input terminal of the operational amplifier, respectively. One end of the third resistor is connected to the output terminal of the operational amplifier, and one end of the fourth resistor is grounded; The operational amplifier is used to output the detection voltage based on the voltage difference between the second capacitor and the third capacitor.

12. The touch detection circuit of claim 11, wherein, The circuit also includes a voltage comparator; The first input terminal of the voltage comparator is connected to a preset power supply voltage, and the second input terminal is connected to the output terminal of the operational amplifier. When the voltage at the second input terminal is greater than the voltage at the first input terminal, the first signal is output to indicate that the touch sensor has been touched.

13. An electronic device comprising a touch detection circuit as described in any one of claims 1-12.

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