Security fence system

• US 4,829,286 A
• Filed: 05/07/1987
• Issued: 05/09/1989
• Est. Priority Date: 05/20/1986
• Status: Expired due to Fees

• Current Assignee: Magal Security Systems Ltd.
• Original Assignee: Magal Security Systems Ltd.
• Inventors: Zvi, Dank
• Primary Examiner(s): Swann, III, Glen R.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/046,736
• Time in Patent Office: 733 Days
• Field of Search: 340/541, 340/550, 340/555, 350/96.23, 200/61.93
• US Class Current: 340/541
• CPC Class Codes: G08B 13/124 with the breaking or disturbance being optically detected, e.g. optical fibers in the perimeter fence
• CPC Class Codes: G08B 13/186 using light guides, e.g. optical fibres

Abstract

A taut wire protective fence system, including a plurality of taut wires and a sensor, the sensor including apparatus for bending of an optical fiber in response to displacement of a taut wire, thereby producing sensible attenuation of light passing through the optical fiber.

Claims

1. A taut wire protective fence system comprising:

a plurality of taut wires and a sensor, the sensor comprising means for producing bending of an optical fiber in response to displacement of a taut wire, thereby producing sensible attenuation of light passing through the optical fiber,

said sensor comprising

a base;

a taut wire connection element movably mounted with respect to the base and being arranged for association with at least one taut wire, whereby displacement of the at least one taut wire produces displacement of the connection element relative to the base; and

optical fiber engagement means associated with the connection element whereby at least predetermined displacement of the connection element produces bending of an optical fiber, causing a sensible change in transmission of optical signals therethrough,

and wherein said at least one taut wire comprises a pair of taut wires and relative displacement of the pair of taut wires produces movement of the connection element.

2. Apparatus according to claim 1 and wherein said the sensor is operative to provide greater attenuation in an optical fiber in response to a given displacement of a taut wire than would be produced by a corresponding displacement of the optical fiber itself.

3. Apparatus according to claim 2 wherein said sensor comprises means for enhancing the bending of the optical fiber produced by displacement of the taut wire.

4. Apparatus according to claim 3 and wherein said means for enhancing comprises means for producing sharp localized bending of the optical fiber, in response to even relatively small displacements of a taut wire.

5. Apparatus according to claim 1 and also comprising means for sensing changes in the transmission characteristics of the optical fiber and for providing an alarm indication in response thereto.

6. A taut wire fence system according to claim 5 and also comprisng an arrangement of taut wires defining a physical barrier.

7. A taut wire protective fence system comprising:

a plurality of taut wires and a sensor, the sensor comprising means for producing bending of an optical fiber in response to displacement of a taut wire, thereby producing sensible attenuation of light passing through the optical fiber,

said sensor comprising

a base;

a taut wire connection element movably mounted with respect to the base and being arranged for association with at least one taut wire, whereby displacement of the at least one taut wire produces displacement of the connection element relative to the base; and

optical fiber engagement means associated with the connection element whereby at least predetermined displacement of the connection element produces bending of an optical fiber, causing a sensible change in transmission of optical signals therethrough,

and wherein said optical fiber engagement means is rotatably mounted with respect to the base and loosely coupled to the connection element.

8. Apparatus according to claim 7 and wherein said engagement means is coupled for coaxial rotation with the connection element via a viscous material, whereby only relatively short time constant displacements of the taut wire cause rotation of the engagement apparatus and engagement with the optical fiber.

9. Apparatus according to claim 8 and wherein said connection element has associated therewith propeller means engaging the viscous material.

10. Apparatus according to claim 7 and wherein said connection element and said optical fiber engagement means are unitary or fixed together.

11. Apparatus according to claim 10 and wherein connection element and said engagement means comprise an apertured plate which is movably mounted onto the base, the optical fiber being drawn through the aperture and a taut wire being coupled to an extension of the plate, defining the connection element.

12. Apparatus according to claim 10 and wherein said connection element and said optical fiber engagment means comprise a generally cylindrical cap member onto the outside of which is attached a taut wire, the inside surface of which defines a ribbed surface which presses onto optical fibers wound about a flexible core, in response to short time constant displacements of the taut wire, producing changes in the transmission characteristics of the optical fibers.

13. A taut wire protective fence system comprising:

a plurality of taut wires and a sensor, the sensor comprising means for producing bending of an optical fiber in response to displacement of a taut wire, thereby producing sensible attenuation of light passing through the optical fiber,

said sensor comprising

a base;

a taut wire connection element movably mounted with respect to the base and being arranged for association with at least one taut wire, whereby displacement of the at least one taut wire produces displacement of the connection element relative to the base; and

optical fiber engagement means associated with the connection element whereby at least predetermined displacement of the connection element produces bending of an optical fiber, causing a sensible change in transmission of optical signals therethrough,

said system also comprising means for limiting the movement of the connection element to predetermined limits, in order to prevent damage to the optical fiber.