Capacitance type sensor

• US 6,933,732 B2
• Filed: 05/17/2001
• Issued: 08/23/2005
• 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
• Assistant Examiner(s): Dole, Timothy J.
• Application Number:
  US10/471,445
• Publication Number:
  US 20040080216A1
• Time in Patent Office: 1,559 Days
• Field of Search: 324/661, 324/662, 738/620.43
• US Class Current: 324/661
• CPC Class Codes: G01L 1/142 using capacitors
• CPC Class Codes: G01L 5/22 for measuring the force applied to control members, e.g. control members of vehicles, triggers
• 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: H03K 17/98 having a plurality of control members, e.g. keyboard

Abstract

A movable switch electrode (E21) which is contactable with a capacitance element electrode (E1) formed on a substrate (20) and is spaced apart from a fixed switch electrode (E11) formed in an interior of the capacitance element electrode (E1) and having a domed form to cover the fixed switch electrode (E11) is set in place. When a detective member (30) is operated and a force applied from a displacement electrode (40) to the movable switch electrode (E21) reaches a specified value, the movable switch electrode (E21) is elastically deformed and depressed drastically with buckling at the nearly top portion thereof and is brought into contact with the fixed switch electrode (E11). This brings the switch into the ON-state. At this time, an operator is given a pronounced click feeling.

Claims

1. A capacitance type sensor comprising:

a substrate;

a displaceable detective member facing the substrate;

a conductive member disposed between the substrate and the detective member, wherein the conductive member is displaceable in a direction perpendicular to a plane of the substrate in accordance with displacement of the detective member;

a reference electrode disposed on the substrate and electrically connected with the conductive member, wherein the reference electrode is at a predetermined electric potential;

a first electrode disposed on the substrate;

a second electrode disposed on the substrate to constitute a first capacitance element with the conductive member; and

a third electrode electrically connected with the second electrode, wherein the third electrode is contactable with the first electrode, elastically deforming in accordance with displacement of the conductive member, and

wherein, when the first electrode and the third electrode are in contact with each other a signal input to the first electrode is used to identify the displacement of the detective member on the basis of changes in capacitance of the first capacitance element caused by changes in distances between the conductive member and the second electrode.

2. The capacitance type sensor according to claim 1, wherein the third electrode is formed in a domed shape and the first electrode is arranged therein.

3. The capacitance type sensor according to claim 1, wherein a second capacitance element is disposed between the reference electrode and the conductive member.

4. The capacitance type sensor according to claim 1, wherein there are provided two or more groups of the first, second and third electrodes.

5. The capacitance type sensor according to claim 1, which has two groups of the first, second and third electrodes and wherein signals with different phases are fed to a circuit including one of the two groups of electrodes and a circuit including the other of the two groups of electrodes.

6. The capacitance type sensor according to claim 1, which has two groups of the first, second and third electrodes and wherein a CR circuit including one of the two groups of electrodes and a CR circuit including the other of the two groups of electrodes are different in time constant from each other.

7. The capacitance type sensor according to claim 1, which has two groups of the first, second and third electrodes and wherein output signals of signals input to the circuit including one of the two groups of electrodes and the circuit including the other of the two groups of electrodes, respectively, are detected by a signal processing circuit using a logical element.

8. The capacitance type sensor according to claim 7, wherein the logical element performs an exclusive-OR logical operation.

9. The capacitance type sensor according to claim 7, wherein the logical element performs a logical operation OR.

10. The capacitance type sensor according to claim 7, wherein the logical element performs a logical operation AND.

11. The capacitance type sensor according to claim 7, wherein the logical element performs a logical operation AND and a NOT operation.

12. The capacitance type sensor according to claim 1, wherein the second electrode includes a pair of fourth electrodes arranged to be symmetric with respect to a first axis that is defined in the plane of the substrate and a pair of fifth electrodes arranged to be symmetric with respect to a second axis that is perpendicular to the first axis and defined in the plane of the substrate.

13. The capacitance type sensor according to claim 12, wherein the detective member is divided to correspond to the fourth electrodes and the fifth electrodes, respectively.

14. The capacitance type sensor according to claim 1, further comprises:

a sixth electrode formed on the substrate, and

a seventh electrode arranged to be contactable with the reference electrode and spaced apart from the sixth electrode, the seventh electrode being elastically deformable along with displacement of the conductive member, to contact with the sixth electrode.

15. The capacitance type sensor according to claim 14, wherein the detective member is divided to correspond to the second electrodes and the sixth electrodes, respectively.

16. The capacitance type sensor according to claim 1, wherein the conductive member is formed by conductive ink applied to an elastic member.