SU1504523A1 - Capacitive pressure transducer - Google Patents

Abstract

The invention relates to vacuum technology and can be used to measure the pressure of practically any gases in the range of ^{10-3 to 10-5} Pa. The purpose of the invention is to expand the range of measured pressures. When the geometrical parameters of the sensor are fulfilled according to the relation presented, the upper limit of the sensor measurement expands, since its sensitivity decreases 10 ³ times after contact of membrane 1 with ceramic plate 2. Therefore, it takes 10 ³ times to move the central part of the membrane by the same value more pressure value. 1 il.

Description

i | SL

3150

The invention relates to vacuum technology, namely vacuum vacuum, and can be used to measure the pressure of virtually any gas in the range of 10-10 Pa.

The aim of the invention is to expand the range of measured pressures.

The drawing shows a sensor, a general view.

The sensor contains a flat membrane 1 rigidly fixed in the transmitter housing, a ceramic plate 2 with two measuring electrodes 3 and 4 concentrically located relative to each other and at a distance (f from the membrane and an additional electrode 5 at a distance of sGH-LSH from the membrane .

The sensor works as follows.

Under the action of pressures P, membrane 1 bends and changes the distance between the membrane and measuring electrodes 3 and 4. The measurement of the movement of the membrane is carried out according to the difference in capacitance changes between the membrane and measuring electrodes 3 and 4, i.e.

4C 4C -; 3C3 f (P),

where DSD-DS- is the change in capacitance between the membrane and the measuring electrode 4 and 3, respectively. The change in capacitance l C is a function of the target pressure P. When the transducer reaches the upper pressure limit, the membrane is placed on the ceramic disk 2, and with further increase in pressure, a portion of the membrane that is limited by the recess diameter B of the ceramic disk starts to deflect. This changes the capacitance between the membrane 1 and the measuring electrode 5. The variation of this capacitance is a function of pressure.

When performing the geometric parameters of the sensor according to the relation presented, the upper limit of the sensor measurement is expanded, since The sensor sensitivity decreases by a factor of E after contact of the membrane with the ceramic plate. Therefore, it takes 10 times more pressure to move this part of the membrane by the same amount.

The advantage of the sensor is the expansion of the pressure measurement range to high pressures, which, in turn, allows measurements to be made with a single sensor.

Claims (1)

Invention Formula A capacitive pressure sensor containing a movable electrode placed in a housing in the form of a flat membrane, on one side of which there is a measuring pressure chamber and on the other side a reference pressure chamber containing a ceramic plate with two fixed concentric electrodes located on it with a gap relative to the membrane the fact that, in order to expand the range of the measured pressure, a third, disk electrode was inserted into it, a blind hole is made in the center of the board, at the bottom of which there is A third electrode is awaited, with the geometric parameters of the sensor satisfying the ratio (5) 1. - .MO, g about where R is the radius of the membrane; g is the radius of the blind hole; if - Zazo between the membrane and fixed electrodes on the board; ud is the distance from the end of the board to the disk electrode.