Patent GB-1438673-A (GB)
Title: Electronic lock apparatus
IPC: E05B49/00
Filed: 1973-05-29
Abstract: 1438673 Electronic locking apparatus J I WHITMAN 29 May 1973 [30 May 1972] 25543/73 Heading E2A An electronic locking apparatus comprises a key operable means 10, first code forming means for generating a first coded electronic signal in response to operation of the key operable means, second code forming means connected to the first code forming means for generating a second independently determinable coded electronic signal in response only to the generation of the first electronic coded signal, electronic means responsive to the second coded signal to decode the second coded signal and generate an initiating signal and a locking means deactivatable by the initiating signal. As shown the key operable means 10 comprises a rotatable cylinder lock each spring loaded tumbler of which is divided into four parts so as to provide combination of positions of the tumblers in which the cylinder 12 is rotatable. In a predetermined one of these combinations each of the tumblers at the interface of the cylinder 12 and housing 38 either make an electrical circuit or maintain an electrical circuit open. The made electrical circuit(s) give a logic "1" output to a NAND gate and an inverter is placed in the open circuit(s) to also give a logic "1" output to the NAND gate so as to produce the first coded signal (Fig. 4A not shown). Each circuit comprises a conducting sleeve in which a tumbler moves set in an insulating portion of the housing 38. An insulating sleeve 44 is interposed between each sleeve and the interface between the housings 38 and the cylinder 12. A circuit is completed through adjacent segments of a tumbler and the cylinder. For this purpose the segments of the tumbler required for the switch are either of metal or plastics material with a conductive coating. The second code forming means comprises a series of NAND gate to one input of each of which the output from the first mentioned NAND gate is communicated. Depending upon the state of the other input of each of the gates of the series a logic "I" or "O" signal is given. These logic "I" and "O" signals form the second coded signal. The "O" signals are inverted so that logic "I" signals are fed to a further NAND gate comprising the decoding electronic means (Fig. 4B, not shown). Through a further series of NAND gates the correct logic signal at the further NAND gate operates a solenoid which deactivates the locking means. A timing circuit (Fig. 4A, not shown) is provided for allowing the locking apparatus to be unlocked during a predetermined time only from insertion of the key into the key operable means. This comprises a set of switches in series formed by a flange 140, 142, 144, 146, 148 on each tumbler and a corresponding portion of a printed circuit 138, the switches normally being closed but at least one being opened on introduction of the key to activate the timing circuit. The output from the timing circuit forms an input to the first mentioned NAND gate. A signal from the cylinder lock is also provided in the decoding portion of the circuit. In a modification the first coded signal may be formed from a set of logic outputs from "photoelectric" devices, one photo electric device being associated with each tumbler (Fig. 5, not shown). The electronic locking apparatus is disclosed as a security lock on a motor vehicle.