A capacitive distance measuring method, device and calibration method thereof
A distance measurement, capacitive technology, applied in the field of capacitive distance measurement, can solve the problems of difficulty in meeting the requirements of millimeter-level measurement accuracy, the influence of ultrasonic ranging environment is great, and the measurement accuracy is reduced, so as to expand the dynamic range of measurement and increase the measurement accuracy. The effect of large measurement dynamic range and improved measurement accuracy
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Embodiment 1
[0049]A capacitive distance measuring device disclosed in an embodiment of the present invention includes: a probe, an excitation unit, a capacitive voltage conversion unit, a logarithmic amplification processing unit, a data acquisition conversion unit, and a control unit.
[0050] Such as figure 1 As shown, the capacitor Cs is formed between the probe and the tested part. When the relative distance between the tested part and the probe changes, the capacitance of the capacitor Cs changes accordingly. The larger the distance, the smaller the capacitance. By measuring the capacitance The relative distance between the DUT and the probe can be measured.
[0051] Wherein, the excitation unit is connected with the probe, and is used to apply the first excitation signal to the probe; specifically, the excitation unit may include a digital-to-analog converter (Digital-To-Analog Converter, DAC), which is used to generate such as a phase-shifted sine wave signal, Excitation signals s...
Embodiment 2
[0057] Such as figure 2 As shown, on the basis of the aforementioned device, the capacitive distance measuring device disclosed in a preferred embodiment of the present invention further includes a shielding layer arranged on the back of the probe, connected to the excitation unit, and the medium between the probe and the shielding layer can be an insulating isolation material or other filler material;
[0058] Correspondingly, the excitation unit is also used to apply a second excitation signal to the probe; wherein the amplitude and phase of the second excitation signal are the same as those of the first excitation signal. The control unit can also be used to determine the phase, amplitude, etc. of the first excitation signal applied by the excitation unit.
[0059] In a preferred embodiment, the above device may further include a display unit connected to the control unit for displaying the distance value, for example, an electronic display device such as a liquid crystal...
Embodiment 3
[0063] A capacitive distance measuring device disclosed in a preferred embodiment of the present invention, on the basis of the aforementioned device, further includes: image 3 The excitation sampling circuit shown. Among them, the excitation unit is connected to the probe (that is, the probe side of the capacitor Cs) through the sampling resistor Rs, and the excitation signal is applied to the probe; the capacitance-voltage conversion unit is connected to the instrumentation amplifier (Instrumentation Amplifier, INA) across the sampling resistor Rs, for example, A precision low-power instrumentation amplifier to acquire the first voltage signal.
[0064] Specifically, if the formula for calculating the capacitance of a plate capacitor is simplified, the relationship between the voltage and the distance can be approximated as V s =V 0 +k / D, where, Vs represents the voltage across the resistor Rs, V0 represents the relative voltage of the capacitor Cs, D represents the dista...
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