Capacitive distance sensor

Abstract

The invention provides a capacitive distance sensor. The capacitive distance sensor is on the basis of the physical principle that the value of a capacitor is inversely proportional to the distance between capacitor plates; and once a coupling capacitor is generated between the surface of a detected conductor and a capacitance measuring plate on the single side of the surface of a sensor, the distance from the capacitance measuring plate to the surface of the detected conductor can be calculated by measuring the value of the coupling capacitor. The capacitive distance sensor provided by the invention has a circuit structure, and comprises the capacitance measuring plate, a reference capacitor, a capacitor coupling plate, a reference capacitor charging circuit, a capacitance measuring plate discharging circuit, a charge neutralization circuit, a programmable level generator 1, a programmable level generator 2 and a voltage comparator. The capacitive distance sensor has the characteristics of linearization, resistance to shifting, and low noise.

Description

technical field [0001] The invention relates to a capacitive distance sensor, in particular to a miniaturized capacitive distance array sensor for forming a two-dimensional array to sense the three-dimensional depth distribution on the surface of an object. Background technique [0002] Image sensing of the three-dimensional depth distribution on the surface of the object can obtain the surface material, texture, and microstructure of the object. If the three-dimensional depth distribution of the measured surface is caused by strain, the stress distribution can also be converted. When the measured object is a conductor, based on the principle that the capacitance value is inversely proportional to the distance between the capacitor plates, by measuring the coupling capacitance formed between the upper surface of the sensor capacitance measuring plate and the surface of the measured object, it can be converted into The distance between the surface of the measured object and t...

AI Technical Summary

Problems solved by technology

[0005] Finally, the surface to be measured has its own level, which is time-varying, spatially uneven, and unpredictable in some applications

This is equivalent to introducing an unknown level at the other pole of the measured capacitance, which brings drift effects to the capacitance measurement: in the active measurement method, the single drift is small due to AC compensation, but the envelope measurement requires multiple times in time The characteristic of accumulation, the cumulative drift cannot be ignored; in the resistance discharge time measurement method, the drift effect is particularly serious; the charge neutralization method has good robustness to the static characteristics of the drift, but the level change of the measured surface within the discharge time lead to a greater dynamic drift effect

[0006] Due to the advantages and disadvantages of different measurement methods, the current capacitive distance measurement circuit is difficult to fully meet the needs of circuit miniaturization in terms of low noise characteristics, anti-drift characteristics, and linearization characteristics.

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