Electronic lock system with timer/calendar features

Abstract From the Canadian patent

Abstract, An electronic lock system is disclosed in which a key can be assigned a limited lifetime, such as by storing data indicative of an expiration date in a key memory. Whenever the key is used with a lock, the lock first examines this key data and verifies that the key is still timely before performing any operations. After a key's expiration date has passed it is, useless unless a new expiration date is stored in its memory. By this arrangement keys that are lost or stolen soon lose their efficacy and no longer pose a threat to system security. The invention also permits the lock administrator to issue keys with different useful lives so that, for example a person who needs, a key …