RU1797700C - Capacitive matrix pressure pick-up - Google Patents

Abstract

The invention relates to measuring technique and can be used to simultaneously measure pressure and strain. A deformation sensing element 3 of foil is formed on the surface of the test objects on the first dielectric film 1, on the second 5 and fourth 10 dielectric films of the lining 7.13, the screen 12 and the outputs of the 6.11 pressure sensing element. In order to increase the pressure sensitivity of the sensor, a third of the dielectric film 9 located between the second and fourth films is perforated. The foil thickness is 6 ... 33 times greater than the rest of metallized films, and the thickness of the first, second, and fourth dielectric films is the same and makes up 0.4-1.0 of the thickness of the third perforated film. 1 ill. D, and Yo

Description

The invention relates to measuring technique and can be used to measure pressure and deformation during aerodynamic and full-scale tests of aeronautical engineering.

Known film sensor with a sensitive element (SE) of pyroelectric material. A polymer substrate is deposited on a glass plate. On this substrate, the electrodes and a layer of the pyroelectric material SE and the upper electrode are sequentially dusted. This method of assembling the sensors does not provide pressure measurement on the surface of the product without drainage.

The disadvantages include: low reliability of soldering contacts, poor adhesion of the pyroelectric to glass, exposure to external electromagnetic interference and triboelectric effect.

The closest technical solution to the invention is a film capacitive pressure sensor, which consists of four layers of a dielectric film made of a homogeneous material. The first film is an insulator. On the second film, from below, a metallized continuous screen, from above on the surface of this film, metallized upper plates of the sensor. The second plates of the sensors are metallized on the outer surface of the fourth film. Between the second and fourth films, a third of the perforated film is located. The connection of the four films with each other and the installation of the sensor on the surface of the investigated model is carried out using glue.

Such a solution in this design provides a pressure measurement on the surface of the test object without drainage.

The disadvantage of this sensor is that it does not allow measuring pressure and deformations at the same time and is not sufficiently noise immunity.

The purpose of the invention is to expand functionality by simultaneously measuring pressure and deformation.

The technical result is achieved in that in a capacitive matrix pressure sensor containing four dielectric films connected by an adhesive connection in a bag, the first of which is the base of the sensor, while on the upper surfaces of the first and second films and on the lower surface of the fourth film

corresponding screens are formed, in addition, capacitor plates with leads are formed on the upper surface of the second film and on the lower surface of the fourth film, and the third film is perforated, film tensor resistors isolated from the screen located opposite to the capacitor plates are formed on the upper surface of the first film, formed on the surface of the second film, in the areas between their terminals, with the screen and strain gauges located on the upper surface of the first film ,

5 are made of metal foil, the thickness of which is 6 ... 3.3 times greater than the thickness of the capacitor plates, and the first, second and fourth films are made of the same thickness, which is

0 0.4 ... 1.0 of the thickness of the third perforated film.

The drawing shows the structural elements of a capacitive matrix pressure sensor and strain gauge element,

5 The basis of the sensor is the first layer of the dielectric film 1, containing the terminals 2 of the strain gauge element 3 and the screen 4 (Section A-A). The second dielectric film 5 contains conclusions 6, plates 7, SE

0 pressures and screen 8 (section BB). A third of the dielectric film 9 is perforated. The fourth dielectric film 10 is a membrane of the sensor and contains a terminal 11 for supplying polarization voltage, a screen

5 12 and plates 13 (sec. G-D). All films are glued together with glue (sec. DD). All metallized elements on the surface of dielectric films (except for the first dielectric film

0 1) formed by the method of vacuum casing - -. laziness.

Introduction on the surface of the first dielectric film 1 of a foil (from nickel, constantan, etc.) polyamic acid

5 varnish according to known technology allows to form a strain-sensitive element 3 and conclusions 12. on the upper surface of the dielectric film by photolithography method to measure the deformation of the model

0 simultaneously with pressure. The location of the strain-sensing element on the bottom of the first dielectric film is due to the occurrence of the maximum value of force and deformation

5 on this site. In this case, the SEs of pressure (plates 7, 13) in the upper section of the second and fourth dielectric films 5, 10. are located at the place where the maximum value of pressure pulsations is expected. Symmetrical offset plates 7,

13 with respect to the tear-sensitive elements 3 eliminates the mutual influence of the terminals b, 11 with the tear-sensitive elements 3 and the terminals 2 with each other and the surfaces of the dielectric films 1,5, 10 are rationally used.

The design of the strain-sensing element is selected purely symbolic. It can be of any design, proceeding from the requirement of the performed strain measurement.

If the actual thickness of the metal foil for the manufacture of modern tesosensitive elements is 3-10 microns, then the thickness of the metal of metallized dielectric films is in the range of 300-500 A. Then the ratio of the thickness of the foil to the thickness of the metallized film is in the range of 6 ... 33.

In the construction of the sensor, the first 1, second 5, and fourth 10 films are made of the same thickness, which is 0.4-1.0 of the thickness of the third perforated film 9.

The principle of operation of the sensor is as follows. When exposed to pressure at the junction of the strain gauge elements 3, strain stresses arise. On the surface of the sensor, through the dielectric films 10, 9 and 5, the strain-sensitive elements are subjected to a force (pressure). In this case, the deformation of the model is determined by the magnitude of the electric voltage at the output of the strain-sensing element after amplification and determination of the coefficient of strain sensitivity. When the pressure P changes, the dielectric film 10 bends into the perforation cell of the dielectric film 9, and the capacitance C changes

in proportion to the pressure on the value of the DS. In this case, the output voltage taken from the terminals b of the SE pressure is proportional to the polarization voltage and the ratio

A f

-p- U. Pressure changes are judged by a change in capacity.

Claims (1)

SUMMARY OF THE INVENTION A capacitive matrix pressure sensor comprising four dielectric films joined by an adhesive joint in a bag, the first of which is the base of the sensor, and corresponding screens are formed on the upper surfaces of the first and second films and on the lower surface of the fourth film, in addition, capacitor plates with leads are formed on the upper surface of the second film and on the lower surface of the fourth film, and the third film is perforated, characterized in that, in order to expanding functionality due to the simultaneous additional measurement of deformation, film strain gauges isolated from the screen are formed on it on the upper surface of the first film, located opposite to the plates of capacitors formed on the surface of the second film in the areas between their terminals, with the screen and strain gauges located on the top the surface of the first film is made of metal foil, the thickness of which is 6-33 times greater than the thickness of the plates of capacitors. moreover, the first, second and fourth films are made of the same thickness, which is 0.4-1.0 of the thickness of the third perforated film.