System and method for using a capacitive door edge sensor

• US 7,420,347 B2
• Filed: 10/04/2004
• Issued: 09/02/2008
• Est. Priority Date: 10/04/2004
• Status: Active Grant

• Current Assignee: Chamblerlain Group LLC, The Chamberlain Group LLC
• Original Assignee: The Chamberlain Group, Inc. (The Chamberlain Group LLC)
• Inventors: Fitzgibbon, James J.
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): GLASS, ERICK DAVID
• Application Number:
  US10/958,181
• Publication Number:
  US 20060071624A1
• Time in Patent Office: 1,429 Days
• Field of Search: 49 26- 28, 49 13- 14, 49/31, 494/67, 160/29, 160/4, 160 40- 43, 318465-478, 318264-266
• US Class Current: 318/478
• CPC Class Codes: E05F 15/00 Power-operated mechanisms for wings motor-operated accessories in locks for completing closing or initiating opening of a wing E05B17/00
• CPC Class Codes: E05F 15/46 responsive to changes in electrical capacitance
• CPC Class Codes: E05F 15/668 for overhead wings
• CPC Class Codes: E05Y 2201/47 Springs
• CPC Class Codes: E05Y 2400/822 Light emitters, e.g. light emitting diodes [LED]
• CPC Class Codes: E05Y 2600/13 by motors, magnets, springs or weights
• CPC Class Codes: E05Y 2600/45 in or on the fixed frame
• CPC Class Codes: E05Y 2800/40 Physical or chemical protection
• CPC Class Codes: E05Y 2900/00 Application of doors, windows, wings or fittings thereof
• CPC Class Codes: E05Y 2900/106 for garages
• CPC Class Codes: E06B 9/88 for limiting unrolling
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

A system and method for sensing capacitance at the edge of a movable barrier and for detecting an obstruction includes positioning a conductive member within or about a holder. A sensed capacitance between the conductive member and ground. A controller is coupled to the sensor. The controller determines whether an obstruction exists within a path of the barrier by analyzing the sensed capacitance. The conductive member and holder move away from a physical reference as the physical reference is approached such that the sensed capacitance between the conductive member and the physical reference remains below a predetermined threshold.

Claims

1. A system for determining a capacitance at an edge of a movable barrier and detecting an obstruction comprising:

a holder disposed on the moveable barrier;

a conductive member positioned with the holder;

a controller coupled to the conductive member, the controller determining whether an obstruction exists within a path of movement between open and closed positions of the barrier, the controller responsive to and detecting a change in sensed capacitance, the capacitance sensed between the conductive member and a reference that is separated from the moveable barrier, the reference being in a fixed position and minimum distance relative to the moveable barrier; and

wherein the holder prohibits the conductive member from achieving a distance from the reference which is less than a predetermined distance as the reference is approached by the barrier such that the sensed capacitance between the reference and the conductive member remains below a predetermined level.

2. The system of claim 1 wherein the movable barrier is selected from the group consisting of a garage door, a sliding gate, and a swinging door.

3. The system of claim 1 wherein the conductive member comprises a wire.

4. The system of claim 3 wherein the holder comprises a rubber flap.

5. The system of claim 1 wherein the conductive member comprises a rod.

6. The system of claim 1 wherein the reference is selected from the group consisting of ground, a fence post, and a gate structure.

7. A method for determining whether an obstruction exists in a pathway of a movable barrier comprising:

moving a movable barrier;

determining a capacitance between a conductive member and a reference as the movable barrier is moved, the conductive member mounted on the movable barrier, the reference separated from the movable barrier, and in a fixed position and minimum distance relative to the moveable barrier;

determining whether an obstruction exists in a pathway of the movable barrier based upon the capacitance; and

maintaining the conductive member at the minimum distance from the reference as the conductive member approaches the reference so as to maintain a substantially uniform sensed capacitance between the conductive member and the reference in the absence of an obstruction.

8. The method of claim 7 wherein the step of maintaining the conductive member comprises moving a flap with the conductive member located within the flap away from the ground.

9. The method of claim 7 wherein the step of maintaining the conductive member comprises moving the conductive member away from the post of a gate.

10. The method of claim 7 wherein moving a movable barrier comprises moving a garage door.

11. The method of claim 7 wherein moving a movable barrier comprises moving a sliding gate.

12. The method of claim 7 wherein moving a movable barrier comprises moving a swinging gate.

13. A system for determining a capacitance at an edge of a movable barrier and detecting an obstruction comprising:

a holder;

a conductive member positioned with the holder for measuring the capacitance between the conductive member and a reference that is separated from the moveable barrier, the reference being in a fixed position and minimum distance relative to the moveable barrier;

a controller coupled to the conductive member and the holder, the controller is programmed and arranged to communicate with the conductive member such that the capacitance measured between the conductive member and the reference is held at a substantially constant value in the absence of an obstruction as the moveable barrier approaches the reference.

14. The system of claim 13 wherein the conductive member comprises a wire.

15. The system of claim 14 wherein the holder comprises a rubber flap.

16. The system of claim 13 wherein the conductive member comprises a rod.

17. The system of claim 13 wherein the reference is selected from a the group consisting of ground, a fence post, and a gate structure.

18. The system of claim 13 further comprising a DC power source coupled to the conductor member for supplying DC current and power to the conductive member.

19. A method for determining whether an obstruction exists in a pathway of a movable barrier comprising:

moving a movable barrier in a downward direction;

determining a capacitance between a conductive member and the ground as the movable barrier is moved in the downward direction towards the ground, the conductive member mounted on the movable barrier;

determining whether an obstruction exists in a pathway of the movable barrier based upon the capacitance; and

maintaining the conductive member at a minimum distance from the ground as the conductive member approaches the ground so as to maintain a substantially uniform sensed capacitance between the conductive member and the ground in the absence of an obstruction.

20. The method of claim 19 wherein the step of maintaining the conductive member comprises moving a flap with the conductive member located within the flap away from the ground.

21. The method of claim 19 wherein moving a movable barrier comprises moving a garage door.