Differential capacitance displacement conversion and subdivision method and capacitive linear displacement measuring system

Abstract

The invention relates to a differential capacitance displacement conversion and subdivision method and a capacitive linear displacement measuring system. First, the displacement is solved with the use of a conversion reference of differential capacitance displacement, no modulation, demodulation, amplifier or A / D is needed, and measurement and subdivision are simple and accurate; second, differential capacitance variation is converted into pulse width, a circuit needs no zeroing, no noise, parasitic or zero drift interference exists, and the range is not limited and is only related with the series resistance; third, the capacitive linear displacement measuring system is provided by the use of the method and the circuit, the system is large in range and can be used for performing absolute position measurement, a sensor and a circuit of the system are simple, and the system is fully digital, high in precision and good in stability, can be used in harsh environments with water, oil or dust pollution and is better than an optical grating, a ball grid or the like; and fourth, the sensor, the circuit, a display and the like are integrated into a micro (MEMS) device, the precision is at the nanometer level, motion parameters of the MEMS such as mechanical position, displacement, velocity, amplitude and frequency can be accurately measured, and parameter transformation is remotely controlled.

Description

technical field [0001] The invention relates to capacitance displacement measurement technology, in particular to a conversion and subdivision method of differential capacitance displacement and a capacitance type linear displacement measurement system. The conversion of the said differential capacitance displacement has two purposes, the first purpose is to propose the conversion benchmark of the differential capacitance displacement, and the second purpose is to convert the differential capacitance change into a pulse width quantity; this capacitive linear displacement measurement The system is an all-digital type with large range, absolute position measurement, sensor production and simple circuit, and can be used in harsh environments such as water, oil, and dust pollution; there is also miniaturization (MEMS), and the accuracy is nanometer. Background technique [0002] The capacitive sensor started early. In 1920, Wellington manufactured a capacitive micrometer, which ...

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Problems solved by technology

[0041] However, in the above-mentioned first method, the absolute displacement measurement is carried out by obtaining analog quantities, which is easily affected by the inclination of the reading unit. The actual installation and movement of the reading unit cannot be completely parallel to the displacement scale unit. The measured value of the displacement will be different due to the inclination of the reading unit, and the anti-interference ability is poor; moreover, each electrode needs to be cut at a specific position, the manufacturing process is complicated and the cost is high

In the second method, due to the need to include multiple electrodes, the number of electrodes is large, the cost is high, and the realization of connecting each electrode to a signal line with a specified polarity is more complicated.

[0042] It is said that in the CN101995208 (or WO2011018497) patent, a comprehensive analysis and comparison of the problems existing in the prior art shows that the problems existing in the modification are still complicated, so the patent CN101995208 (or WO2011018497) has made further improvements ; It is also true that the electrode pattern as stated in the patent is simpler, each electrode does not need to be cut at a specific position, and the manufacturing process is also very simple, but there are two excitation signal sources and a specific rectangular sensing area, etc., each excitation signal source There are four (or more than four) signals with different phases. The incremental displacement measurement mode is to measure the fraction of displacement, which is still a traditional measurement method. The absolute displacement measurement mode has a large displacement range and a specific rectangular sensing area. The number is large, so the displacement measurement range is limited; both the displacement scale unit and the reading unit have multiple external signal lines, so the connection between the moving part and the fixed part is also a troublesome problem

In short, the comparison above shows that the various problems in the existing technology are all caused by the current measurement method, and it is difficult to completely solve them ideally.

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