Conductive tamper switch for security devices

• US 7,388,484 B2
• Filed: 08/16/2005
• Issued: 06/17/2008
• Est. Priority Date: 08/16/2005
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Hsu, Wen-Hua
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US11/204,781
• Publication Number:
  US 20070040674A1
• Time in Patent Office: 1,036 Days
• Field of Search: 340/539.31, 340/506, 340/545.6, 340/568.1, 340/568.2, 340/572.8, 340/693.5, 340/693.9, 340/693.12, 361/616, 361/672, 361/600, 361/627, 361/644
• US Class Current: 340/539.31
• CPC Class Codes: G06F 21/83 input devices, e.g. keyboards, mice or controllers thereof
• CPC Class Codes: G08B 29/046 prevention of tampering with detection circuits

Abstract

A tamper switch mechanism utilized in security interface devices such as keypad installations to render them tamper-resistant, wherein the devices are generally connected to burglar alarm and fire alarm systems. More particularly, provided is a conductive tamper switch which is installed in a security interface device, such as a keypad, which upon an unauthorized attempt to dislodge the device or keypad from a wall or surface on which it is mounted, will trigger an alarm or generate a warning signal at a monitoring site indicative that an effort at tampering with the device has been effected. Also disclosed is a method of providing the tamper switch mechanism in a security interface device, such as a keypad installation.

Claims

1. In a security interface device, including a keypad having a back panel mountable on a wall surface and a cover panel detachably fastened to said back panel forming a keypad housing containing a printed circuit board and operative components fastened to the interior of said front panel;

the provision of a tamper-detecting indicating mechanism;

comprising;

a tamper switch including an elongate post member having a resiliently compressible element extending between said back panel and circuitry on said printed circuit board, said elongate post member comprising an elongate shaft portion;

a cylindrical element extending co-axially with said shaft portion;

a ring-shaped flange extending about said shaft portion, and said compressible element being a flexible web connecting said ring-shaped flange with said cylindrical element, said elongate post member having an electrically-conductive end contacting the circuitry on said printed circuit board in the mounted position of said keypad on said wall surface, whereby in an activated condition of said keypad, responsive to tampering by a pulling away of said cover panel from said back panel or pulling the keypad from said wall surface causes said electrically-conductive end to disengage from the circuitry on said printed circuit board so as to short or cause a malfunction in said circuitry and trigger a signal indicative of tampering.

2. A security interface device, as claimed in claim 1, wherein said tamper switch forms a gap with said circuitry on said printed circuit board responsive to an unauthorized pulling away of said keypad housing in its entirety from said wall surface so as to initiate a short or malfunction in said circuitry and trigger said tamper-indicating signal.

3. A security interface device, as claimed in claim 1, wherein said back panel includes an aperture enabling said cylindrical element to extend rearwardly outward of said back panel through said aperture and said elongate shaft portion of said tamper switch extends forwardly towards said printed circuit board, whereby mounting of said keypad on said wall surface presses said cylindrical element into the confines of said back panel so as to resiliently compress at least said flexible web biasing said flange into engagement with a support surface on the interior of said back panel and axially press said tamper switch into said keypad to cause said electrically-conductive end to contact the circuitry on said printed circuit board.

4. A security interface device, as claimed in claim 3, wherein said elongate shaft portion includes a through-aperture facilitating an axial compression of at least a portion of said switch so as to exert an enhanced axial pressure between said electrically-conductive end on said shaft portion and the circuitry on said printed circuit board.

5. A security interface device as claimed in claim 3, wherein tampering with said keypad by either pulling said cover panel away from said back panel while said back panel remains mounted on said wall surface or pulling the keypad in its entirety intact from said wall surface causes expansion of said resiliently compressible flexible web and forming a gap between said electrically-conductive end on said tamper switch and the circuitry on said printed circuit board to short the circuitry and trigger a signal indicative of tampering with said keypad.

9. A security interface device, as claimed in claim 3, wherein said elongate shaft portion includes a through-aperture facilitating an axial compression of at least a portion of said switch so as to exert an enhanced axial pressure between said electrically-conductive end on said shaft portion and the circuitry on said printed circuit board.

10. A security interface device as claimed in claim 3, wherein tampering with said keypad by either pulling said cover panel away from said back panel while said back panel remains mounted on said wall surface or pulling the keypad in its entirety intact from said wall surface causes expansion of said resiliently compressible flexible web and forming a gap between said electrically-conductive end on said tamper switch and the circuitry on said printed circuit board to short the circuitry and trigger a signal indicative of tampering with Keypad.

11. A security interface device, as claimed in claim 1 or 6, wherein said tamper switch is constituted of an electrically non-conductive material.

12. A security interface device, as claimed in claim 11, wherein said material is selected from the group consisting of rubber and silicon rubber.

13. A security interface device, as claimed in claim 1, wherein said electrically-conductive end on said tamper switch comprises a pad element fastened or molded to said shaft portion of the tamper switch.

14. A security interface device, as claimed in claim 13, wherein said electrically conductive pad element is constituted of a gold-plated copper disc number.

15. A security interface device, as claimed in claim 13, wherein said electrically conductive pad element is constituted of a metallic, conductive rubber or conductive plastic material composition.

16. A security interface device, as claimed in claim 3 or 7, wherein said cylindrical element of the tamper switch mounts a pad at the protruding end so as to increase the extent of rearward projection of said tamper switch from said back panel prior to mounting on said wall surface so as to compensate for irregularities in the wall surface mounting thereon of said keypad.

6. In a security interface device, including a keypad having a back panel mountable on a wall surface and a cover panel detachably fastened to said back panel forming a keypad housing containing a printed circuit board and operative components fastened to the interior of said front panel;

the provision of a tamper-detecting indicating mechanism;

comprising;

a tamper switch including an elongate post member having a resiliently compressible element extending between said back panel and circuitry on said printed circuit board, said elongate post member comprises an elongate shaft portion;

a cylindrical element extending co-axially with said shaft portion;

a resiliently flexible annular segment connecting said shaft portion and said cylindrical element;

a ring-shaped flange extending about said shaft portion, and said compressible element being a flexible web connecting said ring-shaped flange with said cylindrical element, said elongate post member having an electrically-conductive end contacting the circuitry on said printed circuit board in the mounted position of said keypad on said wall surface, whereby in an activated condition of said keypad, responsive to tampering by a pulling away of said cover panel from said back panel or pulling the keypad from said wail surface causes said electrically-conductive end to disengage from the circuitry on said printed circuit board so as to short or cause a malfunction in said circuitry and trigger a signal indicative of tampering.

7. A security interface device, as claimed in claim 6, wherein said back panel includes an aperture enabling said cylindrical element to extend rearwardly outward of said back panel through said aperture and said elongate shaft portion of said tamper switch extends forwardly towards said printed circuit board, whereby mounting of said keypad on said wall surface presses said cylindrical element into the confines of said back panel so as to resiliently compress each said resiliently flexible annular segment and said flexible web biasing said flange into engagement with a support surface on the interior of said back panel and axially press said tamper switch into said keypad to cause said electrically-conductive end to contact the circuitry on said printed circuit board.

8. A security interface device as claimed in claim 7, wherein tampering with said keypad by either pulling said cover panel away from said back panel while said back panel remains mounted on said wall surface or pulling the keypad in its entirety intact from said wall surface causes expansion of both said resiliently flexible annular segment and said resiliently compressible flexible web and forming a gap between said electrically-conductive end on said tamper switch and the circuitry on said printed circuit board to short or cause a malfunction in the circuitry and trigger a signal indicative of tampering with said keypad.

31. A security interface device, as claimed in claim 6, wherein said tamper switch forms a gap with said circuitry on said printed circuit board responsive to an unauthorized pulling away of said keypad housing in its entirety from said wall surface so as to initiate a short or malfunction in said circuitry and trigger said tamper-indicating signal.

17. A method of providing a security interface device incorporating a tamper-indicating mechanism, including a keypad having a back panel mountable on a wall surface and a cover panel detachably fastened to said back panel forming a keypad housing containing a printed circuit board and operative components fastened to the interior of said front panel;

the method comprising;

providing a tamper switch including an elongate post member having a resiliently compressible element extending between said back panel and circuitry on said printed circuit board, said elongate post member comprises an elongate shaft portion;

a cylindrical element extending co-axially with said shaft portion a ring-shaped flange extending about said shaft portion, and said compressible element being a flexible web connecting said ring-shaped flange with said cylindrical element, said elongate post member having an electrically-conductive end contacting the circuitry on said printed circuit board in the mounted position of said keypad on said wall surface, whereby in an activated condition of said keypad, responsive to tampering by a pulling away of said cover panel from said back panel or pulling the keypad from said wall surface causes said electrically-conductive end to disengage from the circuitry on said printed circuit board so as to short or cause a malfunction in said circuitry and trigger a signal indicative of tampering.

18. A method of providing a security interface device, as claimed in claim 17, wherein said tamper switch forms a gap with said circuitry on said printed circuit board responsive to an unauthorized pulling away of said keypad housing in its entirety from said wall surface so as to initiate a short or malfunction in said circuitry and trigger said tamper-indicating signal.

19. A method of providing a security interface device, as claimed in claim 17, wherein said back panel includes an aperture enabling said cylindrical element to extend rearwardly outward of said back panel through said aperture and said elongate shaft portion of said tamper switch extends forwardly towards said printed circuit board, whereby mounting of said keypad on said wall surface presses said cylindrical element into the confines of said back panel so as to resiliently compress at least said flexible web biasing said flange into engagement with a support surface on the interior of said back panel and axially press said tamper switch into said keypad to cause said electrically-conductive end to contact the circuitry on said printed circuit board.

20. A method of providing a security interface device, as claimed in claim 19, wherein said elongate shaft portion includes a through-aperture facilitating an axial compression of at least a portion of said switch so as to exert an enhanced axial pressure between said electrically-conductive end on said shaft portion and the circuitry on said printed circuit board.

21. A method of providing a security interface device as claimed in claim 19, wherein tampering with said keypad by either pulling said cover panel away from said back panel while said back panel remains mounted on said wall surface or pulling the keypad in its entirety intact from said wall surface causes expansion of said resiliently compressible flexible web and forming a gap between said electrically-conductive end on said tamper switch and the circuitry on said printed circuit board to short or cause a malfunction in the circuitry and trigger a signal indicative of tampering with said keypad.

25. A method of providing a security interface device, as claimed in claim 17 or 22, wherein said tamper switch is constituted of an electrically non-conductive material.

26. A method of providing a security interface device, as claimed in claim 25, wherein said material is selected from the group of materials consisting of rubber and silicon rubber.

27. A method of providing a security interface device, as claimed in claim 17, wherein said electrically-conductive end on said tamper switch comprises a pad element fastened or molded to said shaft portion of the tamper switch.

28. A method of providing a security interface device, as claimed in claim 27, wherein said electrically-conductive pad element is constituted of a gold-plated copper plate member.

29. A method of providing a security interface device, as claimed in claim 27, wherein said electrically-conductive pad element is constituted of a metallic, conductive rubber or conductive plastic material composition.

30. A method of providing a security interface device, as claimed in claim 19, wherein said cylindrical element of the tamper switch mounts a pad at the protruding end so as to increase the extent of rearward projection of said tamper switch from said back panel prior to mounting on said wall surface so as to compensate for irregularities in the wall surface mounting said keypad.

22. A method of providing a security interface device incorporating a tamper-indicating mechanism, including a keypad having a back panel mountable on a wall surface and a cover panel detachably fastened to said back panel forming a keypad housing containing a printed circuit board and operative components fastened to the interior of said front panel;

the method comprising;

providing a tamper switch including an elongate post member having a resiliently compressible element extending between said back panel and circuitry on said printed circuit board, said elongate post member comprising an elongate shaft portion;

a cylindrical element extending co-axially with said shaft portion;

a resiliently flexible annular segment connecting said shaft portion and said cylindrical element;

a ring-shaped flange extending about said shaft portion, and said compressible element being a flexible web connecting said ring-shaped flange with said cylindrical element, said elongate post member having an electrically-conductive end contacting the circuitry on said printed circuit board in the mounted position of said keypad on said wall surface, whereby in an activated condition of said keypad, responsive to tampering by a pulling away of said cover panel from said back panel or pulling the keypad from said wall surface causes said electrically-conductive end to disengage from the circuitry on said printed circuit board so as to short or cause a malfunction in said circuitry and trigger a signal indicative of tampering.

23. A method of providing a security interface device, as claimed in claim 22, wherein said back panel includes an aperture enabling said cylindrical element to extend rearwardly outward of said back panel through said aperture and said elongate shaft portion of said tamper switch extends forwardly towards said printed circuit board, whereby mounting of said keypad on said wall surface presses said cylindrical element into the confines of said back panel so as to resiliently compress each said resiliently flexible annular segment and said flexible web biasing said flange into engagement with a support surface on the interior of said back panel and axially press said tamper switch into said keypad to cause said electrically-conductive end to contact the circuitry on said printed circuit board.

24. A method of providing a security interface device as claimed in claim 23, wherein tampering with said keypad by either pulling said cover panel away from said back panel while said back panel remains mounted on said wail surface or pulling the keypad in its entirety intact from said wall surface causes expansion of said resiliently flexible annular segment and of said flexible web forming a gap between said electrically-conductive end on said tamper switch and the circuitry on said printed circuit board to short or cause a malfunction in the circuitry and trigger a signal indicative of tampering with said keypad.

32. A method of providing a security interface device, as claimed in claim 22, wherein, said tamper switch forms a gap with said circuitry on said printed circuit board responsive to an unauthorized pulling away of said keypad housing in its entirety from said wall surface so as to initiate a short or malfunction in said circuitry and trigger said tamper-indicating signal.