Object detection sensor

• US 7,154,393 B2
• Filed: 05/11/2004
• Issued: 12/26/2006
• Est. Priority Date: 05/14/2003
• Status: Expired due to Fees

• Current Assignee: Omron Automotive Electronics Company Limited (Nidec Corporation)
• Original Assignee: Omron Corporation
• Inventors: Nagayama, Keiichi, Okushima, Akihiro, Sueyasu, Hiroyuki, Kurumado, Yukinori
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Labbees, Edny
• Application Number:
  US10/843,691
• Publication Number:
  US 20050001633A1
• Time in Patent Office: 959 Days
• Field of Search: 340/562, 340/536, 340/436, 340/437, 340/438, 340/552, 341/33, 200/600, 200/181, 200/61.44, 200/61.42
• US Class Current: 340/562
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes
• CPC Class Codes: H03K 2217/960745 Capacitive differential; e.g. comparison with reference capacitance
• CPC Class Codes: H03K 2217/96077 comprising an electrode which is floating

Abstract

An object detection sensor wherein a detection electrode (electrode connected with a detection circuit via a conductor) is not exposed from a surface and an input signal is scarcely reduced when a contact area is small, which is capable of reliably detecting a contact thereof with an object in a manner substantially the same as that in the case of a large contact area even when the contact area is small is provided. The object detection sensor is provided with a sensor case made from an insulating material, a detection electrode (electrode A) disposed on an inner surface of the sensor case, a touch electrode (touch electrode A) disposed at a position opposed to the detection electrode on an outer surface of the sensor case and capacitance-coupled to the detection electrode, and a detection circuit which is connected to the detection electrode and detects a contact of an object with the touch electrode based on a change in electrostatic capacitance between the detection electrode and the ground to output a detection signal.

Claims

1. An object detection sensor comprising:

a supporting member made from an insulating material;

a detection electrode disposed on an inner surface of the supporting member;

a touch electrode which is disposed on an outer surface of the supporting member at a position opposed to the detection electrode and capacitance-coupled to the detection electrode; and

a detection circuit which is connected to the detection electrode and detects a contact of an object with the touch electrode based on a change in electrostatic capacitance between the detection electrode and the ground and to output a detection signal,

wherein a difference correction detection electrode is disposed at a position which is on a periphery of the detection electrode and on the inner surface of the supporting member, and the detection circuit operates a difference between a value corresponding to the electrostatic capacitance between the detection electrode and the ground and a value corresponding to electrostatic capacitance between the difference correction detection electrode and the ground so as to detect a contact of an object with the touch electrode based on the change in the difference and to output a detection signal.

2. The object detection sensor according to claim 1, further comprising a difference correction touch electrode which is disposed on the outer surface of the supporting member at a position opposed to the difference correction detection electrode and capacitance-coupled to the difference correction detection electrode.

3. The object detection sensor according to claim 1, wherein a shield electrode for shielding is provided in such a fashion as to cover a non-detection region including at least a back side of the detection electrode.

4. The object detection sensor according to claim 1, wherein the supporting member has a front face portion projected from a mounting face of a backside;

the touch electrode is disposed on an outer surface of the projected front face portion; and

the detection electrode is disposed on the inner surface of the front face portion.

5. The object detection sensor according to claim 4, wherein a laterally projecting protection portion is formed on each of side rims of the front face portion of the supporting member.

6. The object detection sensor according to claim 1, wherein the supporting member is mounted on a car body in such a fashion that the touch electrode is exposed at a specific position on a surface of the car body, so that the touch electrode functions as a vehicle sensor for detecting a contact of an object with the specific position.

7. The object detection sensor according to claim 6, wherein at least the touch electrode constitutes an accessory member provided on the car body surface.

8. The object detection sensor according to claim 7, wherein at least a portion between the touch electrode and the detection electrode of the supporting member functions as a base of the accessory member provided on the car body surface;

and the touch electrode is in the form of a coating layer for covering an outer surface of the base.