Fiber optic security system

• US 5,055,827 A
• Filed: 02/20/1990
• Issued: 10/08/1991
• Est. Priority Date: 02/20/1990
• Status: Expired due to Fees

• Current Assignee: Harald Philipp
• Original Assignee: Harald Philipp
• Inventors: Philipp, Harald
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Sutcliffe, Geoff
• Application Number:
  US07/482,089
• Time in Patent Office: 595 Days
• Field of Search: 340/568, 340/555, 340/556, 340/557, 340/572, 340/600, 350/96.29, 350/96.15, 24/115 G, 24/136 L, 403/208, 403/215, 455/612
• US Class Current: 340/568.4
• CPC Class Codes: G08B 13/1409 for removal detection of electrical appliances by detecting their physical disconnection from an electrical system, e.g. using a switch incorporated in the plug connector
• CPC Class Codes: G08B 13/1445 with detection of interference with a cable tethering an article, e.g. alarm activated by detecting detachment of article, breaking or stretching of cable furniture, e.g. shelves for displaying merchandise, incorporating tethers to prevent theft A47F7/024, A47F5/0861
• CPC Class Codes: G08B 13/186 using light guides, e.g. optical fibres

Abstract

An optical security system is disclosed for one or more appliances such as a network of computers, terminals, and associated peripheral devices. The system comprises an optical fiber cable that is attached to an appliance through attachment devices that are secure from physical attack. The ends of the optical fiber are connected to a control box to form an optical fiber circuit which senses the amount of light within the fiber at any given time. The alarm device sounds if light within the fiber cable is attenuated through bending or breaking of the fiber cable in an attempted theft of the secured computer. The attachment devices comprise a two piece unit which holds the optical fiber. The first piece is a solid cone that is fastened to the computer component by a screw or adhesive. The second piece is a hollow cone that fits entirely over the solid inner cone. The cones include slots for holding the optical fiber between the cones. The fiber is held by the cones but is able to slide within the cones without breaking or bending the fiber cable. This allows the computer component to be moved without setting off the alarm. The alarm activates only when someone attempts to pry or pull the cones apart, subsequently bending the fiber cable.

Claims

1. An optical security system for protecting an appliance comprising:

a conduit for transmitting light therethrough;

an attachment device for holding said conduit, said device comprising means for attaching said conduit to the appliance;

means for preventing removal of said conduit from said device without first bending said conduit, said preventing means not necessitating the breaking or feeding through of the conduit to facilitate removal of said conduit;

means for controlling said system, said controlling means comprising a means for sensing a disturbance of the light within said conduit, and a means for generating an alert signal in response to said sensing means;

wherein, said optical security system sends an alert signal in response to an attempt to remove said conduit from the appliance which results in a bending or breaking of said conduit and a subsequent disturbance of the light within said conduit.

2. An optical security system as claimed in claim 1, wherein,

said attachment device further comprises means for allowing said conduit to move longitudinally within said device without bending said conduit to allow the appliance to be moved without activating said sensing means.

3. An optical security system as claimed in claim 1, wherein,

said attachment device comprises first and second members, said first member attached to a surface of the appliance, said second member covering said first member and capturing said light conduit between said first and second members.

4. An optical security system as claimed in claim 1, wherein,

said system comprises a plurality of said attachment devices, each of said plurality of devices capable of securing a separate appliance.

5. An optical security system as claimed in claim 1, wherein,

said controlling means further comprises a means for sending and receiving light through said conduit to form a closed light circuit, said sensing means sensing a disturbance in said light circuit in response to one of two conditions, a first condition wherein said conduit is bent and a second condition wherein said conduit is severed.

6. An optical security system as claimed in claim 1, wherein,

said controlling means modulates the light conducted into the conduit.

7. An optical fiber security attachment device for capturing an optical fiber cable of an optical security system and securing the fiber cable to an appliance, comprising:

a base member comprising means for attaching said base member to a surface of the appliance, said base member having a groove for capturing the optical fiber cable;

a cover member comprising means for substantially covering said base member, said cover member having a slot with first and second ends;

a means for preventing removal of the fiber cable from said attachment device without bending the fiber cable;

wherein, the optical fiber cable is securely held between said base member and said cover member by extending through said groove of said base member and exiting out of said first and second ends of said slot of said cover member.

8. An optical fiber security attachment device as claimed in claim 7, wherein,

said groove of said first member extends radially into the center of said base member, said radial groove forming a longitudinal channel through said base member, said channel having first and second open ends at opposite sides of said base member;

said first and second ends of said slot of said cover member are in alignment with said first and second open ends of said groove of said base member, respectively;

wherein, the optical fiber cable is held within said channel of said groove of said base member and extends through said first and second ends of said slot of said cover member.

9. An optical fiber security attachment device as claimed in claim 8, wherein,

said channel of said base member is of equal or greater width than the diameter of the optical fiber cable to allow the fiber cable to slide freely within said base and cover members.

10. A optical fiber security attachment device as claimed in claim 7, wherein,

said base member is formed as a solid cone and said cover member is formed as a hollow cone that fits over said base member.

11. An optical fiber security attachment device as claimed in claim 10, wherein,

said base member includes a cutout adjacent to the appliance, said cutout capable of receiving a fastener for attaching said base member to the appliance.

12. An optical fiber security attachment device as claimed in claim 11, wherein,

said cover member includes a recess on an interior surface of said hollow cone, said recess for allowing a head of said fastener to extend above an exterior surface of said base member.

13. An optical fiber security attachment device as claimed in claim 7, wherein,

said base member includes a cutout, said cutout allowing access to a fastener of the appliance when said cover member is removed from said base member.

14. An optical fiber security attachment device for attaching a flexible optical fiber cable to a surface, comprising:

a first member comprising attachment means for securing said first member to the surface, said first member having a means for holding the fiber cable and allowing the fiber cable to extend through said first member;

a second member comprising means for substantially covering said first member, said second member having a means for allowing the fiber cable to extend through said second member;

said means for allowing the fiber cable to extend through said first member is in alignment with said means for allowing the fiber cable to extend through said second member, said alignment defining a substantially linear passage;

wherein, said fiber cable is held between said first and second members, thereby attaching the fiber cable to the surface.

15. An optical fiber security attachment device, as claimed in claim 14, wherein,

said device further comprising means for allowing the cable to slide freely within said passage.