Kaba-mas Corporation

Lee Stallard

Gerald L Dawson

Daniel L Thompson

An electronic combination lock having a knob which has no divisions or markings relating to the numbers of the combination thereon. The rotation of the knob drives a generator, which produces electrical power. The power generated serves as a power source for the electronics of the lock. A knob position detector indicates to the microprocessor the speed and amount of rotation of the knob. The timing capabilities of the lock provides the opportunity to set the minimum time that can be used in the entering of the combination. The lock waits a period of time, typically, two seconds between the entry of one element of the combination and the lock permitting the entry at the next element of the combination. The microprocessor will also keep a count record of all the failed attempts to open the lock since the last successful operation. If the numbers of tries or attempts to unlock the lock equals or exceeds the number set in the microprocessor microcode, the lock will fail to open even if an authorized combination is subsequently entered. After an error indication is displayed, the lock is disabled to prevent further entry tries, until the lock is reset. In order to eliminate the possibility of correlation between the number displayed and/or entered and knob position, there is a random time delay between the start of knob rotation and the incrementing the number displayed.

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Lexington, KY, United States of America

Lee Stallard