Capacitor detection method and capacitor detection circuit

Abstract

The invention relates to the field of electronics, and discloses a capacitor detection method and a capacitor detection circuit. According to the method, the voltage of a negative input end of an operational amplifier is adjusted to the required reference value, and the voltage of the upper end of a capacitor Cs to be detected can be limited to Vset in the charge transfer phase, i.e. the charge on a sampling capacitor Cs is not completely transferred onto an integrating capacitor Ci. Consequently, the charge conservation principle can also be utilized, and according to the voltage variation of the output end of the operational amplifier, the capacitance of the capacitor to be detected is calculated. Because the voltage of the negative input end of the operational amplifier is adjustable, even if the capacitor with the capacitance varies from a small miicromicro farad to hundreds of miicromicro farads is detected, the voltage of the output end of the operational amplifier can still be controlled within a reasonable scope through adjusting the voltage of the negative input end of the operational amplifier, and accordingly, the capacitor detection method is enabled to detect the capacitor with the capacitance which varies from a small miicromicro farad to hundreds of miicromicro farads.

Description

technical field [0001] The invention relates to the field of electronics, in particular to capacitance detection in capacitive touch or capacitive keys. Background technique [0002] At present, capacitive touch technology is developing rapidly and has brought great convenience to people's life. This technology first divides the touch detection area into a number of grid points that intersect horizontally and vertically, and then detects the change of the capacitance value of the grid points to obtain the touch point location information. [0003] If the capacitive touch technology is classified according to the specific implementation, it includes capacitive buttons, self-inductance capacitive screens, and mutual-inductance capacitive screens. Among them, capacitive buttons and self-inductive capacitive screens have a large range of capacitance to be tested, and some small touch circuit boards Among them, the self-inductance capacitance is only a few picofarads, while in s...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a capacitance detection method and a capacitance detection circuit to solve the contradiction that the capacitance value of the capacitance to be detected varies too much with the specific product and cannot be effectively detected, and the detection circuit will not be additionally added. area, making the capacitance detection circuit more adaptable and versatile

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