Capacitance type sensor

• US 6,842,015 B2
• Filed: 05/23/2001
• Issued: 01/11/2005
• Est. Priority Date: 03/14/2001
• Status: Expired due to Fees

• Current Assignee: Nitta Corporation
• Original Assignee: Nitta Corporation
• Inventors: Morimoto, Hideo
• Primary Examiner(s): Deb, Anjan K.
• Assistant Examiner(s): Benson, Walter
• Application Number:
  US10/168,034
• Publication Number:
  US 20020190727A1
• Time in Patent Office: 1,329 Days
• Field of Search: 324/658, 324/661, 324/662, 324/765, 367/776, 737/80, 738/620.43
• US Class Current: 324/662
• CPC Class Codes: G01L 5/165 using variations in capacitance
• 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
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: H01H 25/008 Operating part movable both angularly and rectilinearly, the rectilinear movement being perpendicular to the axis of angular movement
• CPC Class Codes: H01H 25/041 having a generally flat operating member depressible at different locations to operate different controls
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard

Abstract

A capacitance element electrode (E1) and a reference electrode (E31) are formed on a substrate (20) so as to be opposite to a displacement electrode (40). A dome-shaped movable switch electrode (E21) is disposed so as to be in contact with the reference electrode (E31) and at a distance from a fixed switch electrode (E11) formed inside the reference electrode (E31), and to cover the fixed switch electrode (E11). When an operation is applied to a detective member (30) and a portion of the movable switch electrode (E21) in the vicinity of its top is displaced to be brought into contact with fixed switch electrode (E11), a switch is turned ON. On the other hand, from a change in capacitance value of a capacitance element (C1) formed between the displacement electrode (40) and the capacitance element electrode (E1), the intensity of the force to the detective member (30) can be recognized.

Claims

1. A capacitance type sensor comprising:

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

a detective member being opposite to said substrate;

a conductive member disposed between said substrate and said detective member, said conductive member being displaceable in a Z-axis direction as said detective member is displaced in a Z-axis direction;

a reference electrode formed on said substrate and electrically connected with said conductive member, said reference electrode being grounded or kept at a fixed potential;

a first electrode formed on said substrate;

a second electrode formed on said substrate to constitute a first capacitance element with said conductive member; and

a third electrode disposed at a distance from said first electrode so that said third electrode can be brought into contact with said first electrode as said conductive member is displaced, wherein;

the displacement of said detective member on the basis of a detection, using a signal input to said second electrode, of a change in capacitance value of said first capacitance element caused by a change in distance between said conductive member and said second electrode, and a judgment as to whether said first and third electrodes are in contact with each other, can both be recognized, and

during the displacement of said detective member toward said conductive member, said conductive member starts to displace toward said second electrode before said first and third electrodes are brought into contact with each other.

2. The capacitance type sensor according to claim 1, wherein said third electrode is in contact with said reference electrode.

3. The capacitance type sensor according to claim 1, wherein said third electrode is elastically deformed as said conductive member is displaced.

4. The capacitance type sensor according to claim 1, wherein a second capacitance element is formed between said reference electrode and said conductive member.

5. The capacitance type sensor according to claim 1, wherein a plurality of electrode sets each constituted by a reference electrode as said reference electrode, a first electrode as said first electrode, a second electrode as said second electrode, and a third electrode as said third electrode, are provided.

6. The capacitance type sensor according to claim 1, wherein two electrode sets each constituted by a reference electrode as said reference electrode, a first electrode as said first electrode, a second electrode as said second electrode, and a third electrode as said third electrode, are provided, and cyclic signals different in phase from each other are respectively input to a circuit including one of said electrode sets and a circuit including the other of said electrode sets.

7. The capacitance type sensor according to claim 1, wherein two electrode sets each constituted by a reference electrode as said reference electrode, a first electrode as said first electrode, a second electrode as said second electrode, and a third electrode as said third electrode, are provided, and a CR circuit including one of said electrode sets is different in time constant from a CR circuit including the other of said electrode sets.

8. The capacitance type sensor according to claim 1, wherein two electrode sets each constituted by a reference electrode as said reference electrode, a first electrode as said first electrode, a second electrode as said second electrode, and a third electrode as said third electrode, are provided, and output signals as a result of cyclic signals respectively input to a circuit including one of said electrode sets and a circuit including the other of said electrode sets are detected by a signal processing circuit using a logic element.

9. The capacitance type sensor according to claim 8, wherein said logic element performs an exclusive-OR operation.

10. The capacitance type sensor according to claim 8, wherein said logic element performs an OR operation.

11. The capacitance type sensor according to claim 8, wherein said logic element performs an AND operation.

12. The capacitance type sensor according to claim 8, wherein said logic element performs an AND operation and a NOT operation.

13. The capacitance type sensor according to claim 1, wherein said detective member has been divided so as to correspond to the respective groups of said reference electrode, said first electrode, and said third electrode, and said second electrode.

14. The capacitance type sensor according to claim 1, wherein said second electrode includes a pair of fourth electrodes disposed symmetrically in relation to the Y axis, and a pair of fifth electrodes disposed symmetrically in relation to the X-axis.

15. The capacitance type sensor according to claim 14, wherein said detective member has been divided so as to correspond to said fourth electrodes and said fifth electrodes.

16. The capacitance type sensor according to claim 1, further comprising:

a sixth electrode formed on said substrate; and

a seventh electrode disposed at a distance from said sixth electrode so that said seventh electrode can be elastically deformed to be brought into contact with said sixth electrode, as said conductive member is displaced.

17. The capacitance type sensor according to claim 16, wherein said detective member has been divided so as to correspond to said second electrode and said sixth electrode.

18. The capacitance type sensor according to claim 1, wherein said detective member is covered with an insulating member.

19. The capacitance type sensor according to claim 1, further comprising:

a light source disposed on said substrate; and

a filmy member having a transparent region and a non-transparent region, and

wherein said detective member is transparent.

20. The capacitance type sensor according to claim 19, wherein said conductive member is transparent.

21. The capacitance type sensor according to claim 19, further comprising a colored member with transparency disposed between said light source and said detective member.

22. The capacitance type sensor according to claim 19, wherein said detective member is covered with a transparent insulating member.