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Capacitance detection circuit and detection method

A technology of capacitance detection and self-capacitance detection, which is applied in the direction of capacitance measurement, resistance/reactance/impedance measurement, and electricity measurement, can solve the problems of occupying port resources and processor computing power, and achieve the goal of reducing production costs and improving utilization Effect

Active Publication Date: 2019-08-23
谢晔华
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If multiple capacitive touch buttons are detected, it needs to occupy quite a lot of port resources and computing power of the processor

Method used

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  • Capacitance detection circuit and detection method
  • Capacitance detection circuit and detection method
  • Capacitance detection circuit and detection method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] In this embodiment, the resistance chain to be detected and the switch module are as described in the summary of the invention, see figure 2 .

[0025] The self-capacitance detection module in this embodiment is specifically designed as a self-capacitance detection module 1, which is composed of a detection port, switches SW3, SW4, two comparators, a logic control unit, and a counter.

[0026] The working principle of the self-capacitance detection module 1 in this embodiment: SW3 is turned on, SW4 is turned off, and the current source I1 charges the capacitance of the detection port. When the capacitor voltage reaches the reference voltage VH, SW3 is turned off, SW4 is turned on, and the current source I2 discharges the detection port capacitor. When the capacitor terminal voltage reaches the reference voltage VL, SW3 is turned on, and SW4 is turned off, repeating the above charging and discharging process. Within a certain time T, the number of charge and discharge...

Embodiment 2

[0046] The resistance chain to be detected and the switch module in this embodiment are the same as those described in the summary of the invention above.

[0047] The self-capacitance detection module in this embodiment is specifically designed as a self-capacitance detection module 2, and the self-capacitance detection module 2 is composed of a detection port, switches SW3, SW4, SW5, a comparator, a logic control unit, and a counter, such as Image 6 shown.

[0048] The capacitance detection process of the self-capacitance detection module 2 is as follows. At the beginning of each sampling, SW5 is turned on to discharge the capacitance Cx. Then SW5 is turned off and the charge transfer process starts.

[0049] During the charge transfer process, SW3 is turned on first, and SW4 is turned off, so that the detection port capacitance is charged to the power supply voltage, then SW3 is turned off, and SW4 is turned on, so that the charge on the detection port capacitance is tran...

Embodiment 3

[0052] The capacitance detection circuit of Embodiment 3 is composed of N capacitance detection electrodes, M resistors, a switch module, and a self-capacitance detection module.

[0053] The resistance chain to be detected in this embodiment is as Figure 7 shown.

[0054] The M resistors in this embodiment are divided into 3 groups, and each group is connected in series to form a resistor chain, namely, resistor chain 1, resistor chain 2 and resistor chain 3. One end of the three resistor chains is connected together, and the other end of the three resistor chains is One end is named A1 end, A2 end and A3 end respectively. The N capacitance detection electrodes to be detected are connected to each resistor according to actual needs, and the N capacitance detection electrodes and the M resistors form a resistance chain to be detected.

[0055] The switch module contains 3 switches, each of which takes one input terminal of the 3 switches and connects them together to form t...

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Abstract

The invention relates to a capacitance detection circuit and detection method and provides the capacitance detection circuit. The circuit includes N capacitance detection electrodes, M resistors, a switch module and a self-capacitance detection module; the N capacitance detection electrodes are connected to a resistance chain serially formed by the M resistors to form a to-be-detected resistance chain which can be connected to the self-capacitance detection module through the switch module; through the controlling of the switch module, the two access ends of the to-be-detected resistance chainare respectively connected to the detection ports of the self-capacitance detection module and in high resistance states, so that one capacitance counting value can be detected, and after the time ofa period, the two access ends can be switched, so that the other counting value can be detected; and when touching motion exists, both the two counting values can be changed, and that detection electrodes at which positions in the resistance chain are touched can be judged by calculating the ratio of the changing amount of the two counting values. The one-to-one detection modes in the current arts of the detection ports of capacitance detection circuits and detection electrodes can be changed; and detection can be performed on the multiple detection electrodes by using less capacitance detection circuit ports, so that production costs can be reduced.

Description

technical field [0001] The invention relates to the technical field of capacitance detection, in particular to a capacitance detection circuit and a measurement method. Background technique [0002] At present, capacitive touch buttons are widely used in home appliances, fitness equipment, smart home, industrial control and other fields. In the existing technology, the capacitance change on the capacitance detection electrodes is detected by connecting the capacitance detection electrodes one-to-one to the detection ports of the capacitance detection circuit, so as to realize the detection and judgment of actions such as fingers touching keys. If multiple capacitive touch keys are detected, quite a lot of port resources and computing power of the processor need to be occupied. Contents of the invention [0003] In order to overcome the defect that the existing capacitance detection technology occupies too many detection circuit resources. The invention proposes a technic...

Claims

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Application Information

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IPC IPC(8): G01R27/26G01R31/00
CPCG01R27/2605G01R31/00
Inventor 谢粤芳谢晔华
Owner 谢晔华