Claims
- 1. A security device for blocking the unlocking of a dead-bolt, the device comprising;
- a face plate and a rotatable mm knob located on an exterior side of the face plate, the face plate being adapted to be positioned on an interior face of a door to allow the turn knob to be hand operated with the door in a closed position, the turn knob having locked and unlocked positions, wherein the mm knob is adapted for operating the dead-bolt between corresponding locked and unlocked positions, the faceplate also having first and second apertures extending therethrough, the apertures located on opposite sides of the turn knob, the turn knob having a substantially bar-shaped exterior portion adapted for operation by hand and an interior portion extending through the face plate for connection to the dead-bolt,
- a turn knob blocking mechanism comprising;
- a fulcrum bar having a near end affixed to an interior side of the face plate opposite the turn knob,
- a generally C-shaped linkage composed of first and second parallel laterally spaced bars and a third intermediate bar that is substantially perpendicular to the first and second bars, the first and second bars each being pivotally connected at a near end to opposite ends of the intermediate bar, the first and second bars also having far ends positioned adjacent a corresponding one of the first and second apertures of the face plate, the intermediate bar being pivotally connected at a substantially center portion to a far end of the fulcrum bar thereby allowing rotation of the intermediate bar such that the far end of one or the other first and second bars can be alternatively projected outwards through the corresponding one of the first and second apertures of the faceplate,
- the C-shaped linkage being arranged for pivoting between two extreme positions;
- a first unblocking position, wherein the far end of one of the first and second bars is projected outwards of its corresponding aperture and the far end of the other of the first and second bars is substantially flush with the exterior surface of the face plate such that the turn knob is free to be rotated between its locked and unlocked positions, and
- a blocking position which is achieved by hand pressing the far end of the projecting bar into a second position that is substantially flush with the exterior surface of the face plate, thereby rotating the intermediate bar about its connection to the fulcrum bar and causing the far end of the other of the first and second bars to be projected outwards of its corresponding aperture into a position which is adapted to contact the exterior portion of the turn knob to block rotation of the turn knob to its unlocked position, thereby preventing the dead-bolt from being unlocked,
- the C-shaped linkage being returned to its unblocked position by hand pressing the far end of the projecting bar to a position that is substantially flush with the faceplate, thereby reversing rotation of the intermediate bar.
RELATED APPLICATION
This application is a continuation-in-part of U.S. patent application Ser. No. 08/360,164 filed Dec. 20, 1994, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
51625 |
Apr 1890 |
DEX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
360164 |
Dec 1994 |
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