The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 29, 1991
Filed:
Jan. 27, 1989
Philip D Barrett, Salem, OR (US);
Walter G Henderson, Salem, OR (US);
Wayne F Larson, Salem, OR (US);
Supra Products, Inc., Salem, OR (US);
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 until 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 for only one day can be issued a key that expires the next day. A variety of other operational features are also disclosed.