Force detector and acceleration detector and method of manufacturing the same

• US 20020014126A1
• Filed: 07/17/2001
• Published: 02/07/2002
• Est. Priority Date: 10/12/1990
• Status: Active Grant

• Current Assignee: Wacoh Company
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Granted Patent: US 6,477,903 B2
• Time in Patent Office: Days
• US Class Current: 73/862.043
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• 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 1/023 for acceleration measuring devices
• 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

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. A force detector comprising:

a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force from an external 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 working body adapted to receive a force from the external 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 of said displacement electrode and said fixed electrode, or both the electrodes are constituted by a plurality of electrically independent localized electrodes to form a plurality of capacitance elements by electrodes opposite to each other to detect a force exerted on said working body every multidimensional respective components on the basis of changes in electrostatic capacitance values of said respective capacitance elements.

2. A force detector as set forth in claim 1, wherein any one of said displacement electrode and said fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, thus to form four groups of capacitance elements by using said four group, of localized electrodes, respectively,

a force component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said four groups of capacitance elements,

a force component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said four groups of capacitance elements.

3. A force detector as set forth in claim 1,

wherein any one of said displacement electrode and said fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, thus to form four groups of capacitance elements by using said four groups of localized electrodes, respectively,

a force component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said four groups of capacitance elements,

a force component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said four groups of capacitance elements,

a force 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 capacitance elements belonging to said four groups of capacitance elements.

4. A force detector as set forth in claim 1,

wherein any one of said displacement electrode and said fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, and a fifth group of localized electrode arranged at an intersecting point of said first axis and said second axis, thus to form five groups of capacitance elements by using said five groups of localized electrodes, respectively,

a force component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said five groups of capacitance elements,

a force component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said five groups of capacitance elements,

a force component in a third axis perpendicular to said first axis and said second axis being detected by an electrostatic capacitance value of capacitance element using said fifth group of localized electrode of said five groups of capacitance elements.

5. A force detector as set forth in claim 1 wherein the displacement electrode is formed at said working portion.

6. A force detector as set forth in claim 1 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, and

wherein a predetermined voltage is applied across said first auxiliary electrode and said second auxiliary electrode, or across the displacement electrode and the fixed electrode to allow said flexible substrate to produce displacement by a coulomb force exerted therebetween, thus permitting said force detector to be placed in a state equivalent to a state where a force is exerted thereon from the external.

7. A force 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.

10. A force detector as set forth in claim 1,

wherein said working body is constituted with a magnetic material to detect a force produced on the basis of a magnetic force exerted on said working body, thereby making it possible to carry out detection of magnetism.

8. A force detector comprising:

a flexible substrate including a fixed portion fixed at a detector casing, a working portion to which a force is transmitted from an external, 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 working body adapted to receive a force from the external 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,

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

a piezo electric element formed in a manner that it is put between said displacement electrode and said fixed electrode to transform an applied pressure to an electric signal by said both electrodes to output it to said both electrodes,

wherein said detector detects a force exerted on said working body by an electric signal outputted from said piezo electric element.

9. A force detector as set forth in claim 8 wherein a plurality of displacement electrodes are formed on one surface of the piezo electric element and a plurality of fixed electrodes are formed on the other surface, thus to detect a force exerted on said working body every plural directional components by electric signals obtained from said plurality of electrodes.

11. A force detector as set forth in claim 8,

wherein said working body is constituted with a magnetic material to detect a force produced on the basis of a magnetic force exerted on said working body, thereby making it possible to carry out detection of magnetism.

13. An acceleration detector as set forth in claim 12,

wherein any one of said displacement electrode and said fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, thus to form four groups of capacitance elements by using said four groups of localized electrodes, respectively,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said four groups of capacitance elements,

an acceleration component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said four groups of capacitance elements.

14. An acceleration detector as set forth in claim 12,

wherein any one of said displacement electrode and said fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, thus to form four groups of capacitance elements by using said four groups of localized electrodes, respectively,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said four groups of capacitance elements,

an acceleration component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said four groups of 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 capacitance elements belonging to said four groups of capacitance elements.

15. An acceleration detector as set forth in claim 12,

wherein any one of said displacement electrode and said fixed electrode, or the both electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on a surface where said localized electrodes are formed, and a fifth group of localized electrode arranged at an intersecting point of said first axis and said second axis, thus to form five groups of capacitance elements by using said five groups of localized electrodes, respectively,

an acceleration component in said first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said first axis of said five groups of capacitance elements,

an acceleration component in said second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to two groups of capacitance elements on said second axis of said five groups of capacitance elements,

an acceleration component in a third axis perpendicular to said first axis and said second axis being detected by an electrostatic capacitance value of capacitance element using said fifth group of localized electrode of said five groups of capacitance elements.

16. An acceleration detector as set forth in claim 12 wherein the displacement electrode is formed at said working portion.

17. An acceleration detector as set forth in claim 12,

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, and

wherein a predetermined voltage is applied across said first auxiliary electrode and said second auxiliary electrode, or across the displacement electrode and the fixed electrode to allow said flexible substrate to produce displacement by a coulomb force exerted therebetween, thus permitting said force detector to be placed in a state equivalent to a state where an acceleration is exerted thereon from the external.

18. An acceleration detector as set forth in claim 17 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.

20. An acceleration detector as set forth in claim 19 wherein a plurality of displacement electrodes are formed on one surface of the piezo electric element and a plurality of fixed electrodes are formed on the other surface, thus to detect an acceleration exerted on said weight body every plural directional components by electric signals obtained from said plurality of electrodes.

12. 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 is transmsitted, 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 adapted to produce a force based on an acceleration exerted 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 of said displacement electrode and said fixed electrode, or both the electrodes are constituted by a plurality of electrically independent localized electrodes to form a plurality of capacitance elements by electrodes opposite to each other to detect an acceleration exerted on said weight body every multidimensional respective components on the basis of changes in electrostatic capacitance values of said respective capacitance elements.

19. An acceleration detector comprising:

a flexible substrate including a fixed portion fixed at a detector casing, a working portion to which a force is transmitted from an external, 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 adapted to produce a force based on an acceleration exerted 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,

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

a piezo electric element formed in a manner that it is put between said displacement electrode and said fixed electrode to transform an applied pressure to an electric signal by said both electrodes to output it to said both electrodes,

wherein said detector detects a force exerted on said weight body by an electric signal outputted from said pizeo electric element.

21. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region on a first substrate,

forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said flexible region to have flexibility,

connecting a first surface of a second substrate to a second surface of said first substrate,

cutting said second substrate to thereby form a working body connected to said working region of said first substrate and comprised of a portion of said second substrate, and a pedestal connected to said fixed region of said first substrate and comprised of a portion of said second substrate, and

forming a groove on a first surface of a third substrate and forming a second electrode layer on a bottom surface of said groove, thereafter to connect said third substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween.

22. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region on a first substrate forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said flexible region to have flexibility,

connecting a first surface of a second substrate to a second surface of said first substrate,

cutting said second substrate to thereby form a working body connected to said working region of said first substrate and comprised of a portion of said second substrate, and a pedestal connected to said fixed region of said first substrate and comprised of a portion of said second substrate,

forming, on a first surface of a third substrate, a groove such that said working body can move with a predetermined degree of freedom, thereafter to connect said first surface of said third substrate to a second surface of said second substrate, and

forming a groove on a first surface of a fourth substrate and forming a second electrode layer on a bottom surface of said groove, thereafter to connect said fourth substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween.

23. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region on a first substrate,

forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said flexible region to have flexibility,

forming, on a first surface of a second substrate, a groove such that said working region can move with a predetermined degree of freedom, thereafter to connect said first surface of said second substrate to a second surface of said first substrate, and

forming a groove on a first surface of a third substrate and forming a second electrode layer on a bottom surface of said groove, thereafter to connect said third substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween.

24. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a plurality of unit regions on a first substrate to define, within each unit region, a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region,

forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said respective flexible regions to have flexibility,

connecting a first surface of a second substrate to a second surface of said first substrate,

cutting said second substrate to thereby form, within each unit region, a working body connected to said working region of said first substrate and comprised of a portion of said second substrate, and a pedestal connected to said fixed region of said first substrate and comprised of a portion of said second substrate,

forming a plurality of grooves on a first surface of a third substrate and forming a second electrode layer on a bottom surface of each groove, thereafter to connect said third substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween, and

cutting off every respective unit regions said first, second and third substrates to form independent sensors, respectively.

25. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a plurality of unit regions on a first substrate to define, within each unit region, a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region,

forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said respective flexible regions to have flexibility,

connecting a first surface of a second substrate to a second surface of said first substrate,

cutting said second substrate to thereby form, within each unit region, a working body connected to said working region of said first substrate and comprised of a portion of said second substrate, and a pedestal connected to said fixed region of said first substrate and comprised of a portion of said second substrate,

forming, on a first surface of a third substrate, a groove such that said working body can move with a predetermined degree of freedom, thereafter to connect said first surface of said third substrate to a second surface of said second substrate,

forming a plurality of grooves on a first surface of a fourth substrate and forming a second electrode layer on a bottom surface of each groove, thereafter to connect said fourth substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween, and

cutting off every respective unit regions said first, second, third and fourth substrates to form independent sensors, respectivcely.

26. A method of manufacturing a physical quantity detector utilizing changes in an electrostatic capacitance, said method comprising the steps of:

defining a plurality of unit regions on a first substrate to define, within each unit region, a working region, a flexible region adjacent to said working region, and a fixed region adjacent to said flexible region,

forming a first electrode layer on a first surface of said first substrate,

carrying out a processing for partially removing said first substrate in order to allow said respective flexible regions to have flexibility,

forming, on a first surface of a second substrate, a groove such that said working region can move with a predetermined degree of freedom, thereafter to connect said first surface of said second substrate to a second surface of said first substrate,

forming a plurality of grooves on a first surface of a third substrate and forming a second electrode layer on a bottom surface of each groove, thereafter to connect said third substrate to said first substrate so that said second electrode layer faces to said first electrode layer with a predetermined spacing therebetween, and

cutting off every respective unit regions said first, second and third substrates to form independent sensors, respectively.