A capacitive micro-gap displacement test system based on flexible circuit board

Abstract

The invention discloses a capacitive micro-gap displacement test system based on a flexible circuit board. The system comprises a flexible circuit board, a capacitor plate, a digital bridge and a computer. The capacitor plate comprises a large capacitor plate and a small capacitor plate which are relatively parallelly installed. The vertical projection of the small capacitor plate toward the large capacitor plate falls on the large capacitor plate. The large capacitor plate and the small capacitor plate are respectively installed on two flexible circuit boards. The two capacitor plates are asymmetrically arranged and have different sizes, which effectively reduces the adverse effect of edge effect on the inverse proportional relationship between capacitance value and displacement, allows a certain installation error, reduces the requirement for assembly accuracy, and enables the application to have excellent assembly adaptability and reduce the adverse effect of edge effect. A shielding layer is also arranged to reduce electromagnetic environment interference.

Description

Technical Field

[0001] The invention belongs to the technical field of sensor testing, and in particular relates to a capacitive micro-gap displacement testing system based on a flexible circuit board. Background Art

[0002] At present, there are many methods to realize micro-gap displacement sensors, mainly including optical fiber micro-gap displacement sensors, image micro-gap displacement sensors, and eddy current micro-gap displacement sensors. Among them, the optical fiber micro-gap displacement sensor inserts the optical fiber deep into the gap. Due to the high brittleness and large turning radius of the optical fiber, it is easy to be damaged; the image micro-gap displacement sensor uses a camera to observe the displacement change, which requires a high installation space; the eddy current micro-gap displacement sensor uses an alternating electromagnetic field to measure the displacement change, which is easily disturbed by the electromagnetic environment and requires a high installation space; and the traditional flat capacitive displacement sensor uses a rigid substrate and is only suitable for planar measurement positions.

[0003] Therefore, it is urgent to develop a capacitive micro-gap displacement testing system based on a flexible circuit board to solve the above problems. Summary of the invention

[0004] In order to solve the problems raised in the above background technology, the present invention provides a capacitive micro-gap displacement testing system based on a flexible circuit board.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A capacitive micro-gap displacement test system based on a flexible circuit board, comprising:

[0007] Flexible circuit board; the flexible circuit board consists of two pieces, and they are respectively installed on the structural members on both sides of the gap;

[0008] Capacitor plates; the capacitor plates include a large capacitor plate and a small capacitor plate which are relatively parallel mounted, and a vertical projection of the small capacitor plate toward the large capacitor plate falls on the large capacitor plate; the large capacitor plate and the small capacitor plate are respectively mounted on two flexible circuit boards;

[0009] A digital bridge for measuring the capacitance value of a capacitor plate; the digital bridge is electrically connected to the large capacitor plate and the small capacitor plate respectively;

[0010] A computer is used to calculate the displacement of the structural members on both sides of the gap after reading the digital bridge test data; the computer is connected to the digital bridge for communication.

[0011] Specifically, the flexible circuit board includes a first circuit board and a second circuit board;

[0012] The first circuit board includes a first shielding layer, a second shielding layer, and a signal layer, wherein the signal layer of the first circuit board is disposed between the first shielding layer and the second shielding layer; and the small capacitor plate is mounted on the signal layer of the first circuit board;

[0013] The second circuit board includes a third shielding layer, a fourth shielding layer, and a signal layer, wherein the signal layer of the second circuit board is disposed between the third shielding layer and the fourth shielding layer; and the large capacitor plate is mounted on the signal layer of the second circuit board;

[0014] The first shielding layer and the fourth shielding layer are respectively installed on the structural members at both sides of the gap; in the direction opposite to the small capacitor plate and the large capacitor plate, the second shielding layer is provided with a notch exposing the small capacitor plate; the third shielding layer is provided with a notch exposing the large capacitor plate;

[0015] The small capacitor plate and the large capacitor plate are electrically connected to the digital bridge through signal leads and coaxial cables; the signal leads are all placed on the signal layer.

[0016] Preferably, the second shielding layer and the third shielding layer have the same size; the first shielding layer and the fourth shielding layer have the same size.

[0017] Preferably, the thickness of the first circuit board and the second circuit board are both 0.1 mm-0.2 mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] In the capacitive micro-gap displacement test system, the two capacitor plates are set asymmetrically and with different sizes, which effectively reduces the adverse effect of the edge effect on the inverse proportional relationship between the capacitance value and the displacement, and allows a certain installation error, reducing the requirements for assembly accuracy, so that the present application has excellent assembly adaptability and reduces the adverse effects of the edge effect; and a shielding layer is also set to reduce electromagnetic environment interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a capacitive micro-gap displacement test system based on a flexible circuit board of the present application;

[0021] Figure 2 It is a schematic diagram of the structure of the capacitor plate in this application;

[0022] Figure 3 It is a schematic diagram of the installation structure of the capacitor plate and the flexible circuit board in this application;

[0023] In the figure: 101—structural parts on both sides of the gap, 102—flexible circuit board, 1021—first shielding layer, 1022—second shielding layer, 1023—third shielding layer, 1024—fourth shielding layer, 1025—coaxial cable, 103—digital bridge, 104—computer, 201—large capacitor plate, 202—small capacitor plate, 203—signal lead. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention provides the following technical solutions:

[0026] like Figure 1-3 As shown, a capacitive micro-gap displacement testing system based on a flexible circuit board 102 includes:

[0027] Flexible circuit board 102; the flexible circuit board 102 consists of two pieces, and is respectively installed on the structural members 101 on both sides of the gap;

[0028] Capacitor plates; the capacitor plates include a large capacitor plate 201 and a small capacitor plate 202 which are relatively parallelly mounted, and a vertical projection of the small capacitor plate 202 toward the large capacitor plate 201 falls on the large capacitor plate 201; the large capacitor plate 201 and the small capacitor plate 202 are respectively mounted on two flexible circuit boards 102;

[0029] A digital bridge 103 for measuring the capacitance value of the capacitor plate; the digital bridge 103 is electrically connected to the large capacitor plate 201 and the small capacitor plate 202 respectively;

[0030] A computer 104 is used to calculate the displacement of the structural members 101 on both sides of the gap after reading the test data of the digital bridge 103 ; the computer 104 is in communication connection with the digital bridge 103 .

[0031] like Figure 3 As shown, the flexible circuit board 102 includes a first circuit board and a second circuit board;

[0032] The first circuit board includes a first shielding layer 1021, a second shielding layer 1022, and a signal layer, wherein the signal layer of the first circuit board is disposed between the first shielding layer 1021 and the second shielding layer 1022; the small capacitor plate 202 is mounted on the signal layer of the first circuit board;

[0033] The second circuit board includes a third shielding layer 1023, a fourth shielding layer 1024, and a signal layer, wherein the signal layer of the second circuit board is disposed between the third shielding layer 1023 and the fourth shielding layer 1024; the large capacitor plate 201 is mounted on the signal layer of the second circuit board;

[0034] The first shielding layer 1021 and the fourth shielding layer 1024 are respectively installed on the structural members 101 at both sides of the gap; in the direction opposite to the small capacitor plate 202 and the large capacitor plate 201, the second shielding layer 1022 is provided with a notch exposing the small capacitor plate 202; the third shielding layer 1023 is provided with a notch exposing the large capacitor plate 201;

[0035] The small capacitor plate 202 and the large capacitor plate 201 are electrically connected to the digital bridge 103 through the signal lead wires 203 and the coaxial cable 1025; the signal lead wires 203 are all placed on the signal layer.

[0036] like Figure 3 As shown, the second shielding layer 1022 and the third shielding layer 1023 have the same size; the first shielding layer 1021 and the fourth shielding layer 1024 have the same size.

[0037] Preferably, the thickness of the first circuit board and the second circuit board are both 0.1 mm-0.2 mm. The thickness of the first circuit board and the second circuit board of 0.1 mm-0.2 mm ensures a small impact on the structural members 101 on both sides of the gap.

[0038] When this application is working, two flexible circuit boards 102 are installed on both sides of the gap, deep into the plane or arc gap, to form a flat capacitor, and the displacement change on both sides of the gap (the change in the width of the gap in the relative direction between the capacitor plates) is reversed by measuring the capacitance change. This application utilizes the advantages of the flexible circuit board 102 that it is bendable, high in strength, and strong in flexibility, as well as the inverse proportional relationship between the flat capacitor and the displacement to obtain the high sensitivity of the capacitor to the displacement change under small displacement conditions, and adopts an asymmetric design to reduce the influence of the edge effect and the requirements for installation accuracy. The test system establishes a correction model including area coefficient and parasitic capacitance, realizes micro-gap displacement testing with high requirements for installation space and measurement accuracy, and has high assembly adaptability and reliability. The computer 104 communicates with the digital bridge 103 via USB, obtains capacitance test data, and uses special software for capacitance correction and gap settlement.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A capacitive micro-gap displacement test system based on a flexible circuit board, characterized in that: include: Flexible circuit boards; The flexible circuit board consists of two pieces, which are respectively installed on the structural members on both sides of the gap; Capacitor plates; The capacitor plates include a large capacitor plate and a small capacitor plate which are relatively parallelly mounted, and a vertical projection of the small capacitor plate toward the large capacitor plate falls on the large capacitor plate; the large capacitor plate and the small capacitor plate are respectively mounted on two flexible circuit boards; A digital bridge for measuring the capacitance value of a capacitor plate; the digital bridge is electrically connected to the large capacitor plate and the small capacitor plate respectively; A computer for calculating the displacement of the structural members on both sides of the gap after reading the digital bridge test data; the computer is in communication connection with the digital bridge; The flexible circuit board includes a first circuit board and a second circuit board; The first circuit board includes a first shielding layer, a second shielding layer, and a signal layer, wherein the signal layer of the first circuit board is disposed between the first shielding layer and the second shielding layer; and the small capacitor plate is mounted on the signal layer of the first circuit board; The second circuit board includes a third shielding layer, a fourth shielding layer, and a signal layer, wherein the signal layer of the second circuit board is disposed between the third shielding layer and the fourth shielding layer; and the large capacitor plate is mounted on the signal layer of the second circuit board; The first shielding layer and the fourth shielding layer are respectively installed on the structural members at both sides of the gap; in the direction opposite to the small capacitor plate and the large capacitor plate, the second shielding layer is provided with a notch exposing the small capacitor plate; the third shielding layer is provided with a notch exposing the large capacitor plate; The small capacitor plate and the large capacitor plate are electrically connected to the digital bridge through signal leads and coaxial cables; the signal leads are all placed on the signal layer.

2. A capacitive micro-gap displacement test system based on a flexible circuit board according to claim 1, characterized in that: The second shielding layer and the third shielding layer have the same size; the first shielding layer and the fourth shielding layer have the same size.

3. The capacitive micro-gap displacement test system based on a flexible circuit board according to claim 1, characterized in that: The thickness of the first circuit board and the second circuit board are both 0.1 mm-0.2 mm.

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