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Circuit of testing capacitance and capacitance type pressure transmitter

A capacitive detection, capacitive technology, applied in the direction of fluid pressure measurement using capacitance changes, can solve the problems of measurement accuracy, high cost, etc., to avoid the introduction of AC interference, simplify the measurement circuit, easy to nonlinear and temperature drift Effect

Inactive Publication Date: 2005-10-26
ZHEJIANG SUPCON TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a capacitance detection circuit and a capacitive pressure transmitter to solve the problem of using two CB555 multivibrators in the existing capacitive pressure transmitter for front-end capacitance measurement in the prior art. This creates technical problems with high costs and compromised measurement accuracy

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  • Circuit of testing capacitance and capacitance type pressure transmitter
  • Circuit of testing capacitance and capacitance type pressure transmitter
  • Circuit of testing capacitance and capacitance type pressure transmitter

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Embodiment Construction

[0022] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0023] The core of the present invention is that the front-end detection circuit of the pressure transmitter is switched by a multi-way switch, and then the self-excited oscillator is used to time-share the sampling of the capacitors on both sides to obtain the frequency value, thereby ensuring that the conversion on both sides uses the same oscillation circuit, thereby simplifying the circuit, thereby avoiding the problem of affecting the measurement accuracy due to individual differences in the pressure measurement multivibrator circuit composed of two CB555s.

[0024] See figure 1 , is a functional block diagram of the capacitance detection circuit of the present invention, including three parts: a capacitive pressure sensor 11 , a multi-way switch 12 , and a capacitance frequency conversion circuit 13 . Wherein, the capacitive pressure sensor 11 includes a press...

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Abstract

The invention provides a capacitance detecting circuit, which comprises the capacitance pressure sensor, the multi-way switch and the capacitance frequency converting circuit. The capacitance pressure sensor converts the outside pressure exchanging signals into the capacitance changing values; the multi-way switch switches the capacitances of the two sides; the capacitance frequency converting circuit is the self-exciting oscillator circuit and converts the measured capacitance signals output by the multi-way switch into the frequency signals. The invention adopts the multi-way switch and the same square-wave self-excited oscillator to sample and fully makes use of the charging performance of the capacitance and avoids the interference of the AC power supply. The invention also protects the capacitance pressure transmitter adopting the above capacitance detecting circuit.

Description

technical field [0001] The invention relates to the field of industrial control, in particular to a capacitive pressure transmitter applied to industrial process control, and in particular to the improvement of the front-end measurement circuit of the pressure transmitter. Background technique [0002] Capacitive pressure transmitters are widely used in industrial process control. For capacitive pressure transmitters, the front-end circuit is the capacitance detection circuit. There are two types of basic circuits for capacitance detection: one is to use the capacitor as an impedance element and transform it in the way of resistance-voltage conversion, but the power supply must use AC power; the other is to make full use of the charge and discharge characteristics of the capacitor for transformation. [0003] At present, most capacitance-voltage conversion methods are used in capacitive pressure transmitters to set up capacitance detection circuits, so an oscillation circui...

Claims

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Application Information

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IPC IPC(8): G01L9/12
Inventor 丁云吴忠陈健
Owner ZHEJIANG SUPCON TECH
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