Capacitive distance sensor

Abstract

The present invention relates to a capacitive distance sensor. The capacitive distance sensor comprises a measurement polar plate of a capacitor to be measured, a reference capacitor Cref, a switch S3, a switch S4, a charging / discharging circuit of the capacitor to be measured, a charging / discharging circuit of the reference capacitor, a fully differential sampling / holding circuit and a source follower. A capacitor to be measured Cf is formed on the surface of the measurement polar plate of the capacitor to be measured and the surface of a measured conductor; the measurement polar plate of thecapacitor to be measured is connected with the charging / discharging circuit of the capacitor to be measured through the switch S3, and is connected with the source follower; one end of the referencecapacitor Cref is connected with the charging / discharging circuit of the reference capacitor through the switch S4, and is connected with the source follower; the other end of the reference capacitorCref is connected with a system ground Vss; the input end of the fully differential sampling / holding circuit is connected with the voltage output end of the source follower; and two input ends of thesource follower are respectively connected with the capacitor to be measured Cf and the reference capacitor Cref. The capacitive distance sensor is not sensitive to the parasitic effect, and is high in anti-noise capability and high in measurement precision.

Description

technical field [0001] The invention belongs to the field of sensor design, and in particular relates to a capacitive distance sensor. Background technique [0002] With the rapid development of the Internet of Things, the application of sensors is becoming more and more extensive, and there are more and more types. At present, the sensor principle for detecting the distance and depth of the conductor surface is basically by detecting the capacitance value of the coupling capacitor, and the depth of the conductor surface distance is obtained indirectly by the inverse ratio of the size of the coupling capacitor and the distance. When the surface of the conductor to be measured and the capacitance measuring plate form a coupling capacitance, the size of the coupling capacitance can be measured through the circuit, and then the distance between the surface of the object to be measured and the capacitance measuring plate can be obtained by the formula D=ζ*S / C distance. Among t...

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Problems solved by technology

At present, these methods are affected by parasitic effects, especially when the capacitance to be measured and the parasitic capacitance are of the same magnitude, the error is often large; at the same time, when measuring a small capacitance, device noise and power supply jitter will bring large errors to the measurement

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