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US 4,283,718 AGranted
Door alarm device
AssigneeSynco National Ltd.
InventorsEdward A. Butler, Francis R. Savoie
Life of this patent
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AssigneeSynco National Ltd.
InventorsEdward A. Butler, Francis R. Savoie
Estimating the term…
A signalling device for use in combination with a door so as to signal when the door is attempted to be opened as by inward pivotal motion with respect to the frame in which such door is supported. Normally the alarm is an audible one such as a horn or siren, and in this manner, attempts to open the door are brought to the attention of those inside the structure. The device functions as a dead bolt lock and the signal aspect of the device may be overridden by a key-operated deactivation assembly. Generally the device operates by means of a transversely slidable bolt which may have electrical contact on the inner surface thereof for engagement with a contact on the inside of the door or housing attached thereto. Other contact locations are also contemplated. The bolt may be spring biased away from the door or housing contact and an appropriate electrical circuit is closed and the signal activated upon door movement as by attempted entry.
A device for signalling door movement as by attempted entry comprising, a door frame, a door mounted in said frame for movement between respective open and closed positions relative to said frame, a housing having an inner wall affixed to said door including an elongated bolt mounted thereon for transverse movement with respect thereto and to said door between a first non-activatable position wherein said door may be freely opened and a second activatable position, one end of said bolt adapted to contact said door frame in said activatable position so as to fixedly position such with respect to said door frame and so as to enable said door and said housing to move at least slightly relative to and towards said bolt, electrical signal means, a pair of electrical signal contacts on said housing and in opposition to said bolt, a leaf spring having one end connected to one of said contacts and the other end normally disposed in spaced relation with said other contact, said leaf spring contacting said bolt so as to spring bias said bolt away from the inner wall of said housing whereby moving said door towards its open position causes said spring other end and said other contact to engage and said signal to be activated.
Dependencies are inferred from the claim text.