Detector for a physical quantity having a self-testing function

• US 5,492,020 A
• Filed: 11/30/1992
• Issued: 02/20/1996
• Est. Priority Date: 03/30/1991
• Status: Expired due to Term

• Current Assignee: Kazuhiro Okada
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): Biegel, Ronald L.
• Application Number:
  US07/952,753
• Time in Patent Office: 1,177 Days
• Field of Search: 73/862.626, 73/862.68, 73/517 B, 73/1 D, 73/862.041
• US Class Current: 73/862.626
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• CPC Class Codes: G01L 5/165 using variations in capacitance
• CPC Class Codes: G01L 5/167 using piezoelectric means
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A fixed substrate (10) having rigidity and a flexible substrate (20) having flexibility are arranged in such a manner that they are opposite to each other. Both the substrates are fixed at their peripheral portions by a detector casing (40). A working body (30) is connected onto the lower surface of the flexible substrate. Test electrodes (11t, 13t, 15t) are formed on the lower surface of the fixed substrate, and fixed electrodes (11, 13, 15) are further formed through an insulating layer (16). Displacement electrodes (21, 23, 25) are formed on the upper surface of the flexible substrate. When an acceleration is exerted on the working body, the flexible substrate is bent, so the distance between the fixed electrode and the displacement electrode is varied. By detecting the change of distance as a change of the electrostatic capacitance between both the electrodes, it is possible to detect an acceleration exerted. In order to carry out the operation test of this detector, a voltage is applied across the test electrode and the displacement electrode, thus allowing coulomb force to be exerted between both the electrodes. Thus, the flexible substrate is bent by coulomb force, resulting in the same state as the state where an acceleration is exerted. By examining a change of the electrostatic capacitance between the fixed electrode and the displacement electrode, the operation test can be conducted.

Claims

1. A detector for a physical quantity having a self-testing function, the detector comprising:

a tubular detector casing;

a continuous flexible substrate placed inside the casing, said flexible substrate having an outer peripheral portion supported by an inner wall of the casing;

a fixed, rigid substrate placed inside the casing above said flexible substrate and fixed to the casing so as to face said flexible substrate with a spacing therebetween;

a working body connected to a lower surface of said flexible substrate at a central portion thereof so that said flexible substrate is bent when a force caused by an external physical action is applied to said working body;

a displacement electrode supported on an upper surface of said flexible substrate so as to be displaced when the flexible substrate is bent;

a fixed electrode supported on a lower surface of said fixed substrate so as to face said displacement electrode;

a test electrode supported on said lower surface of said fixed substrate so as to face said flexible electrode, said test electrode and said fixed electrode being electrically insulated from each other;

detection means for generating an electric signal which indicates a change of an electrostatic capacitance between said displacement electrode and said fixed electrode; and

voltage application means for applying a predetermined voltage across said test electrode and said displacement electrode for calibration purposes.

2. A detector for physical quantity having a self-testing function, .the detector comprising:

a tubular detector casing;

a continuous flexible substrate placed inside the casing, said flexible substrate having an outer peripheral portion supported by an inner wall of the casing;

a fixed, rigid substrate placed inside the casing above said flexible substrate and fixed to the casing so as to face said flexible substrate with a spacing therebetween;

a working body connected to a lower surface of said flexible substrate at a central portion thereof so that said flexible substrate is bent when a force caused by an external physical action is applied to said working body;

a displacement electrode supported on an upper surface of said flexible substrate so as to be displaced when the flexible substrate is bent;

a fixed electrode supported on a lower surface of said fixed substrate so as to face said displacement electrode;

a test electrode supported on said upper surface of said flexible substrate so as to face said fixed electrode, said test electrode and said displacement electrode being electrically insulated from each other;

detection means for generating an electric signal which indicates a change of an electrostatic capacitance between said displacement electrode and said fixed electrode; and

voltage application means for applying a predetermined voltage across said test electrode and said fixed electrode for calibration purposes.

3. A detector for physical quantity having a self-testing function, the detector comprising:

a tubular detector casing;

a continuous flexible substrate placed inside the casing, said flexible substrate having an outer peripheral portion supported by an inner wall of the casing;

a fixed, rigid substrate placed inside the casing above said flexible substrate and fixed to the casing so as to face said flexible substrate with a spacing therebetween;

a working body connected to a lower surface of said flexible substrate at a central portion thereof so that said flexible substrate is bent when a force caused by an external physical action is applied to said working body;

a displacement electrode supported on an upper surface of said flexible substrate so as to be displaced when the flexible substrate is bent;

a fixed electrode supported on a lower surface of said fixed substrate so as to face said displacement electrode;

a first test electrode supported on said upper surface of said flexible substrate so as to face said fixed substrate, said first test electrode and said displacement electrode being electrically insulated from each other;

a second test electrode supported on said lower surface of said fixed substrate so as to face said first test electrode, said second test electrode and said fixed electrode being electrically insulated form each other;

a detection means for generating an electric signal which indicates a change of an electrostatic capacitance between said displacement electrode and said fixed electrode; and

voltage application means for applying a predetermined voltage across said first test electrode and said second test electrode for calibration purposes.