Multi-dimensional and acceleration detector

• US 5,406,848 A
• Filed: 08/18/1994
• Issued: 04/18/1995
• Est. Priority Date: 10/12/1990
• Status: Expired due to Term

• Current Assignee: Kazuhiro Okada
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): Dougherty, Elizabeth L.
• Application Number:
  US08/292,496
• Time in Patent Office: 243 Days
• Field of Search: 73/862.041, 73/862.042, 73/862.043, 73/862.626, 73/862.68, 73/862.69, 73/718, 73/724, 73/721, 73/727, 73/780, 73/518 , 73/DIG. 4, 73/517 R, 361/283
• US Class Current: 73/514.32
• CPC Class Codes: G01L 1/144 with associated circuitry G01L1/146 and G01L1/148 take precedence
• CPC Class Codes: G01L 5/165 using variations in capacitance
• CPC Class Codes: G01L 5/167 using piezoelectric means
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/105 by magnetically sensitive devices
• 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: Y10S 73/04 Piezoelectric
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

An electrode layer is formed on the upper surface of a first substrate, and a processing for partially removing the substrate is carried out in order to allow the substrate to have flexibility. To the lower surface of the first substrate, a second substrate is connected. Then, by cutting the second substrate, a working body and a pedestal are formed. On the other hand, a groove is formed on a third substrate. An electrode layer is formed on the bottom surface of the groove. The third substrate is connected to the first substrate so that both the electrodes face to each other with a predetermined spacing therebetween. Finally, the first, second and third substrates are cut off every respective unit regions to form independent sensors, respectively. When an acceleration is exerted on the working body, the first substrate bends. As a result, the distance between both the electrodes changes. Thus, an acceleration exerted is detected by changes in an electrostatic capacitance between both the electrodes.

Claims

1. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force produced on the basis of an acceleration to be detected is transmitted, and a flexible portion having flexibility formed between said fixed portion and said working portion,

a fixed substrate fixed on said detector casing so as to face said flexible substrate,

a weight body to produce a force based on an acceleration to be detected and to transmit said force to said working portion of said flexible substrate,

a displacement electrode formed on a surface, which faces to said fixed substrate, of said flexible substrate, and

a fixed electrode formed on a surface, which faces to said flexible substrate, of said fixed substrate,

wherein any one or both of said displacement electrode and said fixed electrode are constituted by two localized electrodes to form two capacitance elements by using said two localized electrodes, respectively, a first localized electrode to form a first capacitance element being located in a positive area with respect to a first axis of coordinates, a second localized electrode to form a second capacitance element being located in a negative area with respect to said first axis, said first axis and a second axis being perpendicular to each other on a surface where said localized electrodes are formed,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of said first and second capacitance elements,

an acceleration component in a third axis direction perpendicular to said first axis and said second axis being detected by a sum of electrostatic capacitance values of said first and second capacitance elements.

2. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force produced on the basis of an acceleration to be detected is transmitted, and a flexible portion having flexibility formed between said fixed portion and said working portion,

a fixed substrate fixed on said detector casing so as to face said flexible substrate,

a weight body to produce a force based on an acceleration to be detected and to transmit said force to said working portion of said flexible substrate,

a displacement electrode formed on a surface, which faces to said fixed substrate, of said flexible substrate, and

a fixed electrode formed on a surface, which faces to said flexible substrate, of said fixed substrate,

wherein any one or both of said displacement electrode and said fixed electrode are constituted by four localized electrodes to form four capacitance elements by using said four localized electrodes, respectively, a first localized electrode to form a first capacitance element being located in a positive area with respect to a first axis of coordinates, a second localized electrode to form a second capacitance element being located in a negative area with respect to said first axis, a third localized electrode to form a third capacitance element being located in a positive area with respect to a second axis of coordinates, a fourth localized electrode to form a fourth capacitance element being located in a negative area with respect to said second axis, said first axis and said second axis being perpendicular to each other on a surface where said localized electrodes are formed,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of said first and second capacitance elements,

an acceleration component in said second axis direction being detected by a difference between electrostatic capacitance values of said third and fourth capacitance elements.

3. An acceleration detector as set forth in claim 2, wherein an acceleration component in a third axis direction perpendicular to said first axis and said second axis being detected by a sum of electrostatic capacitance values of said first to fourth capacitance elements.

4. An acceleration detector as set forth in claim 2, wherein the displacement electrode is formed at said working portion.

5. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force produced on the basis of an acceleration to be detected is transmitted, and a flexible portion having flexibility formed between said fixed portion and said working portion,

a fixed substrate fixed on said detector casing so as to face said flexible substrate,

a weight body to produce a force based on an acceleration to be detected and to transmit said force to said working portion of said flexible substrate,

a displacement electrode formed on a surface, which faces to said fixed substrate, of said flexible substrate, and

a fixed electrode formed on a surface, which faces to said flexible substrate, of said fixed substrate,

wherein any one or both of said displacement electrode and said fixed electrode are constituted by five localized electrodes to form five capacitance elements by using said five localized electrodes, respectively, a first localized electrode to form a first capacitance element being located in a positive area with respect to a first axis of coordinates, a second localized electrode to form a second capacitance element being located in a negative area with respect to said first axis, a third localized electrode to form a third capacitance element being located in a positive area with respect to a second axis of coordinates, a fourth localized electrode to form a fourth capacitance element being located in a negative area with respect to said second axis, said first axis and said second axis being perpendicular to each other on a surface where said localized electrodes are formed, a fifth localized electrode to form a fifth capacitance element being located on the surface containing said first axis and said second axis, said fifth localized electrode having a substantially symmetrical shape with respect to an intersecting point of said first axis and said second axis,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of said first and second capacitance elements,

an acceleration component in said second axis direction being detected by a difference between electrostatic capacitance values of said third and fourth capacitance elements,

an acceleration component in a third axis direction perpendicular to said first axis and said second axis being detected by an electrostatic capacitance value of said fifth capacitance element.

6. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force produced on the basis of an acceleration to be detected is transmitted, and a flexible portion having flexibility formed between said fixed portion and said working portion,

a fixed substrate fixed on said detector casing so as to face said flexible substrate,

a weight body to produce a force based on an acceleration to be detected and to transmit said force to said working portion of said flexible substrate,

a displacement electrode formed on a surface, which faces to said fixed substrate, of said flexible substrate, and

a fixed electrode formed on a surface, which faces to said flexible substrate, of said fixed substrate,

wherein there is further provided an auxiliary substrate so that said fixed substrate, said flexible substrate and said auxiliary substrate are oppositely arranged in order recited, respectively,

wherein a first auxiliary electrode is formed on a surface, which faces to said auxiliary substrate, of said flexible substrate,

wherein a second auxiliary electrode is formed on a surface, which faces to said flexible substrate, of said auxiliary substrate.

7. An acceleration detector as set forth in claim 6, wherein said flexible substrate is constituted with a conductive material, said first auxiliary electrode and said displacement electrode being formed by a portion of the conductive flexible substrate.

8. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force produced on the basis of an acceleration to be detected is transmitted, and a flexible portion having flexibility formed between said fixed portion and said working portion,

a fixed substrate fixed on said detector casing so as to face towards said flexible substrate,

a weight body to produce a force based on an acceleration to be detected and to transmit said force to said working portion of said flexible substrate,

a displacement electrode formed on a surface, which faces towards said fixed substrate, of said flexible substrate,

a fixed electrode formed on a surface, which faces towards said flexible substrate, of said fixed substrate,

wherein one of said displacement and said fixed electrodes is constituted by two localized electrodes to form two capacitance elements each comprising a respective one of said two localized electrodes and a portion of the other of said electrodes opposite thereto,

said surface of said flexible substrate lying in a plane, and

said weight body being connected to said flexible substrate at the geometric center thereof and extending from said flexible substrate in a direction perpendicular to the plane of said flexible substrate surface, said weight body being effective for similarly changing the spacing between the electrodes of each of said two capacitance elements in response to an acceleration component applied to said weight body along said direction, and for non-similarly changing the spacing between the electrodes in response to an acceleration component perpendicular to said direction.