Anti-pinch sensor

• US 7,821,275 B2
• Filed: 04/13/2009
• Issued: 10/26/2010
• Est. Priority Date: 10/13/2006
• Status: Expired due to Fees

• Current Assignee: Brose Fahrzeugteile GmbH & Company KG Hallstadt (Brose)
• Original Assignee: Brose Fahrzeugteile GmbH & Company KG Hallstadt (Brose)
• Inventors: Mueller, Wolf-Christian, Wuerstlein, Holger, Weingaertner, Thomas
• Primary Examiner(s): Natalini; Jeff
• Assistant Examiner(s): Baldridge; Benjamin M
• Application Number:
  US12/422,691
• Publication Number:
  US 20090256578A1
• Time in Patent Office: 561 Days
• Field of Search: 324/663
• US Class Current: 324/663
• CPC Class Codes: E05F 15/46 responsive to changes in electrical capacitance
• CPC Class Codes: E05Y 2900/50 for vehicles
• CPC Class Codes: G01D 18/002 Automatic recalibration G01D18/008 takes precedence
• CPC Class Codes: G01D 5/2405 by varying dielectric
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

An anti-pinch sensor, particularly for detecting an obstacle in the path of an actuating element of a motor vehicle is provided, having a sensor body, a measuring electrode, which is disposed in the sensor body and to which a measuring potential can be applied, a calibrating electrode, which is electrically disconnected and disposed in the sensor body adjacent to the measuring electrode, and a control unit. The control unit controls the measuring electrode and the calibrating electrode such that the measuring potential and the calibrating potential are equal in a measuring phase, and differ from each other in a calibrating phase.

Claims

1. A capacitive anti-pinch sensor for detecting an obstacle in a path of an actuating element of a motor vehicle, the anti-pinch sensor comprising:

a sensor body with an electrically isolated measuring electrode that is provided in the sensor body and to which a measuring potential can be applied;

a calibrating electrode, which is provided in the sensor body, directly adjacent to the measuring electrode and to which a calibrating potential can be applied; and

a control unit, which controls the measuring electrode and the calibrating electrode so that the measuring potential and the calibrating potential are substantially equal in a measurement phase and differ from one another in a calibration phase, wherein the control unit measures and stores a value of a calibration capacitance during the calibration phase of the capacitive anti-pinch sensor, and uses the measured calibration capacitance value to correct the value of a measurement capacitance detected in the measurement phase of the capacitive anti-pinch sensor, to account for the presence of water, dirt or other contaminants on a surface of the sensor body.

2. The anti-pinch sensor according to claim 1, wherein the control unit is configured to control each of the measuring electrode and the calibrating electrode with an AC voltage, wherein the AC voltages differs from one another in their phases or in their frequencies.

3. The anti-pinch sensor according to claim 1, wherein the control unit is configured to connect the measuring electrode to a ground potential in the calibration phase.

4. The anti-pinch sensor according to claim 1, wherein the control unit is a microcontroller.

5. The anti-pinch sensor according to claim 1, wherein the measuring electrode and the calibrating electrode are each formed comb-shaped, whereby the comb structures of the measuring electrode and calibrating electrode interdigitate.

6. The anti-pinch sensor according to claim 1, wherein the measuring and calibrating electrodes are formed flat and the surface area of the measuring electrode is greater than the surface area of the calibrating electrode.

7. The anti-pinch sensor according to claim 1, wherein two measuring electrodes, particularly two structurally identical measuring electrodes, are provided, which are disposed in edge regions of the sensor body.

8. The anti-pinch sensor according to claim 1, which comprises at least one separate shielding electrode, which is configured to direct a measuring field into a hazard region in the measurement phase.

9. The anti-pinch sensor according to claim 8, wherein the shielding electrode is configured to direct a calibration field into a near zone in the calibration phase.

10. The anti-pinch sensor according to claim 8, wherein the shielding electrode is divided into individual, separated single shielding electrodes, each arranged opposite the measuring and calibration electrodes.

11. The anti-pinch sensor according to claim 1, further comprising an additional electrode between the calibrating electrode and the measuring electrode, the additional electrode have substantially a same potential applied as a potential to the calibrating electrode.

12. The anti-pinch sensor according to claim 1, wherein the sensor body is made of a flexible support material.

13. The anti-pinch sensor according to claim 1, wherein the anti-pinch sensor is formed as a flexible flat cable.

14. The anti-pinch sensor according to claim 12, wherein the sensor body comprises a flexible conductor structure.

15. The anti-pinch sensor according to claim 1, wherein the sensor body extends in a substantially longitudinal direction, and the electrodes are divided along the longitudinal direction each into individually controllable single electrodes.

16. The anti-pinch sensor according to claim 1, further comprising a counter electrode provided opposite to the measuring electrode and the calibrating electrode, the counter electrode being formed by a body of the motor vehicle.

17. A method for detecting an obstacle in a path of an actuating element of a motor vehicle using a capacitive anti-pinch sensor, the method comprising:

applying a measuring potential to an electrically isolated measuring electrode provided in a sensor body that is part of the capacitive anti-pinch sensor;

applying a calibrating potential to a calibrating electrode provided in the sensor body adjacent to the measuring electrode, the measuring potential and the calibrating potential being substantially equal in a measurement phase and differing from one another in a calibration phase;

measuring and storing a value of a calibration capacitance during the calibration phase, and

correcting a value of a measurement capacitance using the stored value of the calibration capacitance.