Capacitance type sensor

• US 20040104735A1
• Filed: 05/28/2003
• Published: 06/03/2004
• Est. Priority Date: 11/30/2000
• Status: Active Grant

• Current Assignee: Nitta Corporation
• Original Assignee: Nitta Corporation
• Inventors: Morimoto, Hideo
• Granted Patent: US 6,989,677 B2
• Time in Patent Office: Days
• US Class Current: 324/660
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks

Abstract

Capacitance element electrodes (E1 to E5) and a grounded reference electrode (E0) are formed on a substrate (20). At a position opposite to these electrodes (E0 to E5), a displacement electrode (40) is disposed that is Z-axially deformable as a detective member (30) is externally operated to move Z-axially. The displacement electrode (40) cooperates with the reference electrode (E0) and capacitance element electrodes (E1 to E5) to form capacitance elements (C0 to C5), respectively. Each of the capacitance elements (C1 to C5) is connected in series with the capacitance element (C0) with respect to a signal externally input. Changes in the capacitance values of the capacitance elements (C1 to C5) as the detective member (30) is moved are detected to sense the displacement of the detective member (30).

Claims

1. A capacitance type sensor characterized in that said sensor comprises:

a conductive member determining an XY-plane in a defined XYZ three-dimensional coordinate system;

a pair of capacitance element electrodes cooperating with said conductive member to form first capacitance elements, respectively;

a reference electrode cooperating with said conductive member to form a second capacitance element, said reference electrode being grounded or kept at a certain potential; and

a detective member Z-axially movable to move said conductive member or said pair of capacitance element electrodes Z-axially, and each of said first capacitance elements and said second capacitance element are connected in series with each other with respect to a signal input to each of said capacitance element electrodes in said pair, and said sensor can sense displacement of said detective member on the basis of detection of changes in the respective capacitance values of said first capacitance elements caused by changes in the intervals between said conductive member and said capacitance element electrodes in said pair.

5. The capacitance type sensor according to any one of claims 1 to 4, characterized by comprising a single reference electrode.

6. The capacitance type sensor according to any one of claims 1 to 4, characterized by comprising a plurality of reference electrodes.

7. The capacitance type sensor according to any one of claims 1 to 6, characterized by comprising pairs of capacitance element electrodes.

8. The capacitance type sensor according to any one of claims 1 to 7, characterized in that signals different in phase from each other are supplied to a circuit including one of said capacitance element electrodes in said pair and a circuit including the other of said capacitance element electrodes.

9. The capacitance type sensor according to any one of claims 1 to 8, characterized in that a CR circuit including one of said capacitance element electrodes in said pair differs in time constant from a CR circuit including the other of said capacitance element electrodes.

10. The capacitance type sensor according to any one of claims 1 to 9, characterized in that each of said signals periodically repeats a high level and a low level, and said sensor further comprises a control element having a function of discharging said first capacitance element when said signal is at the low level.

11. The capacitance type sensor according to claim 10, characterized in that an open-collector type inverter element is used as said control element.

12. The capacitance type sensor according to any one of claims 1 to 11, characterized in that output signals obtained from signals respectively input to a circuit including one of said capacitance element electrodes in said pair and a circuit including the other of said capacitance element electrodes are detected with a signal processing circuit utilizing a logic element.

13. The capacitance type sensor according to claim 12, characterized in that said logic element performs an exclusive-OR operation.

14. The capacitance type sensor according to claim 12, characterized in that said logic element performs an OR operation.

15. The capacitance type sensor according to claim 12, characterized in that said logic element performs an AND operation.

16. The capacitance type sensor according to any one of claims 1 to 15, characterized by further comprising an insulating film formed in close contact with said pair of capacitance element electrodes and said reference electrode to cover them.

2. A capacitance type sensor characterized in that said sensor comprises:

a substrate determining an XY-plane in a defined XYZ three-dimensional coordinate system;

a detective member being opposite to said substrate;

a conductive member disposed in between said substrate and said detective member, said conductive member being Z-axially movable as said detective member is Z-axially moved;

a pair of capacitance element electrodes formed on said substrate and cooperating with said conductive member to form first capacitance elements, respectively; and

a reference electrode formed on said substrate and cooperating with said conductive member to form a second capacitance element, said reference electrode being grounded or kept at a certain potential, and each of said first capacitance elements and said second capacitance element are connected in series with each other with respect to a signal input to each of said capacitance element electrodes in said pair, and said sensor can sense displacement of said detective member on the basis of detection of changes in the respective capacitance values of said first capacitance elements caused by changes in the intervals between said conductive member and said capacitance element electrodes in said pair.

3. A capacitance type sensor characterized in that said sensor comprises:

a conductive member determining an XY-plane in a defined XYZ three-dimensional coordinate system;

a pair of capacitance element electrodes cooperating with said conductive member to form first capacitance elements, respectively;

a reference electrode cooperating with said conductive member to form a second capacitance element, said reference electrode being grounded or kept at a certain potential;

an insulating member disposed in between said conductive member and said pair of capacitance element electrodes; and

a detective member movable along said XY-plane to move said insulating member or said conductive member and said pair of capacitance element electrodes along said XY-plane, and

each of said first capacitance elements and said second capacitance element are connected in series with each other with respect to a signal input to each of said capacitance element electrodes in said pair, and said sensor can sense displacement of said detective member on the basis of detection of changes in the respective capacitance values of said first capacitance elements caused by a change, along said XY-plane, of the position of an end portion of said insulating member between said conductive member and said pair of capacitance element electrodes.

4. A capacitance type sensor characterized in that said sensor comprises:

a substrate determining an XY-plane in a defined XYZ three-dimensional coordinate system;

a detective member being opposite to said substrate;

a conductive member being opposite to said substrate;

a pair of capacitance element electrodes formed on said substrate and cooperating with said conductive member to form first capacitance elements, respectively;

a reference electrode formed on said substrate and cooperating with said conductive member to form a second capacitance element, said reference electrode being grounded or kept at a certain potential; and

an insulating member disposed in between said conductive member and said pair of capacitance element electrodes, and movable in parallel with said substrate as said detective member is moved along said XY-plane, and

each of said first capacitance elements and said second capacitance element are connected in series with each other with respect to a signal input to each of said capacitance element electrodes in said pair, and said sensor can sense displacement of said detective member on the basis of detection of changes in the respective capacitance values of said first capacitance elements caused by a change, along said XY-plane, of the position of an end portion of said insulating member between said conductive member and said pair of capacitance element electrodes.

17. A capacitance type sensor characterized in that said sensor comprises:

a substrate determining an XY-plane in a defined XYZ three-dimensional coordinate system;

a detective member being opposite to said substrate;

a conductive member disposed in between said substrate and said detective member, said conductive member being Z-axially movable as said detective member is Z-axially moved;

a pair of first capacitance element electrodes formed on said substrate symmetrically with respect to a Y-axis and cooperating with said conductive member to form first capacitance elements, respectively;

a pair of second capacitance element electrodes formed on said substrate symmetrically with respect to an X-axis and cooperating with said conductive member to form second capacitance elements, respectively;

a third capacitance element electrode formed on said substrate near an origin and cooperating with said conductive member to form a third capacitance element; and

a reference electrode formed on said substrate and cooperating with said conductive member to form a fourth capacitance element, said reference electrode being grounded or kept at a certain potential, and

each of said first, second, and third capacitance elements and said fourth capacitance element are connected in series with each other with respect to a signal input to each of said first to third capacitance elements, and said sensor can sense displacement of said detective member on the basis of detection of changes in the respective capacitance values of said first to third capacitance elements caused by changes in the intervals between said conductive member and said first to third capacitance element electrodes.

18. The capacitance type sensor according to claim 17, characterized in that a protrusion is formed on said conductive member at a position opposite to said third capacitance element electrode.

19. The capacitance type sensor according to claim 17 or 18, characterized in that said detective member is divided so as to correspond to said first capacitance element electrodes, said second capacitance element electrodes, and said third capacitance element electrode, respectively.

20. The capacitance type sensor according to claim 17 or 18, characterized in that said detective member is divided so as to correspond to said first and second capacitance element electrodes and said third capacitance element electrode, respectively.

21. The capacitance type sensor according to any one of claims 17 to 20, characterized in that at least par of a surface of said conductive member opposite to said first to third capacitance element electrode is made uneven in height.

22. The capacitance type sensor according to any one of claims 17 to 21, characterized in that said conductive member comprises a displacement portion movable as said detective member is moved by receiving an external force, a fixed portion fixed to said substrate, and an interconnecting portion for interconnecting said displacement and fixed portions,

said first and second capacitance element electrodes are formed outside said third capacitance element electrode, and

said reference electrode is formed outside said first and second capacitance element electrodes.

23. The capacitance type sensor according to any one of claims 17 to 21, characterized in that said reference electrode comprises a first reference electrode and a second reference electrode, either of which is grounded or kept at a certain potential,

said conductive member is divided so as to correspond to said first and second capacitance element electrodes and said third capacitance element electrode, respectively,

said first reference electrode is formed outside said third capacitance element electrode,

said first and second capacitance element electrodes are formed outside said first reference electrode, and

said second reference electrode is formed outside said first and second capacitance element electrodes.

24. The capacitance type sensor according to any one of claims 17 to 21, characterized in that said reference electrode is formed outside said third capacitance element electrode, and

said first and second capacitance element electrodes are formed outside said reference electrode, and

said sensor further comprises a fourth capacitance element electrode disposed in contact with said reference electrode and at a distance from said third capacitance element electrode to cover said third capacitance element electrode, said fourth capacitance element electrode being capable of coming into contact with said third capacitance element electrode when said conductive member is moved as said detective member is moved by receiving an external force.

25. The capacitance type sensor according to any one of claims 17 to 24, characterized in that said detective member and said conductive member are formed into one body.

26. The capacitance type sensor according to any one of claims 17 to 25, characterized in that said conductive member is made of an elastic material.

27. The capacitance type sensor according to any one of claims 17 to 26, characterized by further comprising a supporting member for supporting said conductive member, said supporting member being made of an elastic material.