Abstract: An electronic combination lock is provided with and incorporates the enhanced feature of covert entry detection and notification. Whenever the bolt of an electronic lock provided with this enhancement is retracted to its withdrawn or unlocked position and whenever the lock has not received an authorized combination enabling the movement of the bolt, movement of the bolt is detected and the electronics of the lock is powered for a time sufficient to record an indication of the covert entry in its non-volatile memory. Upon normal operation at a subsequent time, the indication of covert entry is read from the non-volatile memory and a visual indication is displayed to the operator to inform the operator that covert entry has occurred.

Abstract: To prevent the opening of an electronic combination lock by using a strong magnet to operate a stepper motor, a magnetic interlock is included in the lock structure. A magnetic pin is held in a retracted position by a small magnet when a strong attack magnet is positioned to attempt to open the lock, the magnetic pin is attracted from the holding magnet and extended to bridge the bolt and lock housing, blocking the retraction of the bolt.

Abstract: Optical character recognition in which registration of a stored, character image is changed from, for example, center to lower left depending on the individual character template or equivalent description against which the image is being compared. Accuracy is improved because the registration form used is one known to provide the greatest elements distinguishing the character of the template from the closest other character which might be presented.