Theft preventing device

Claim 1

A portable and self-contained theft preventing device comprising: a lockable unitary lock body having a housing; a lock mechanism disposed in said housing; a cable member having one end thereof secured to said unitary lock body and the other end thereof fastenable to said unitary lock body; at least one light-conducting member extending through and along said cable member; an alarm system contained in said lock body housing; said housing being formed at one side thereof with a cable receiving hole for receiving said other end of said cable member and a key receiving hole for receiving a key member; said alarm system including an alarm device, a drive circuit operable to drive said alarm device when said lock body is in its locking position, and an inhibiting circuit for inhibiting operation of said drive circuit, said inhibiting circuit being completed by said light-conducting member; said inhibiting circuit includes a light-emitting element operable in synchronism with a locking operation to initiate emission of light therefrom, a light-receiving element which generates a voltage in accordance with the amount of light received thereby, and an amplifier circuit connected to said light-emitting element; said light-emitting element and said light-receiving element being disposed within said housing of said lock body; said lock mechanism having a lock cylinder which is operable by means of said key member; said alarm system further including a power source and a switch mechanism interposed between said power source and said drive and inhibiting circuits; and said switch mechanism being operatively associated with said lock cylinder.