In recent years, it has become common to provide key assemblies which have devices therein which either generate a coded signal or are sensitive to an outside code reading mechanism which reads the code contained in each key assembly's device. One such device may be an electronic transponder. A common use in recent years has been in a motor vehicle ignition key and lock arrangement.
When the key assembly is inserted in its receiving mechanism, such as an ignition key lock, the code embedded in or emitted by the transponder of the key assembly is matched with a corresponding code detector to permit the key to unlock the lock so that the vehicle engine ignition system may be actuated. Actuation of the key may also unlock a steering shaft lock which has prevented the steering wheel from being moved, and it may unlock a lock installed in an electrical circuit or a door or the like which is locked.
Should a key assembly which does not provide a proper code signal be inserted in the lock, the code detector may actuate any controlled unlocked locks. It may actuate a theft warning device, interior and/or exterior lights, and render a starter mechanism inoperative, by way of example.
Numerous patents have been issued on this general subject, the more pertinent ones known to the inventor of the invention claimed herein showing conventional transponder key assemblies being the U.S. Pat. No. 5,433,096--Janssen et al (1995) and U.S. Pat. No. 5,632,168--Yano (1997). The list below includes these patents and less pertinent patents and publications disclosing conventional transponder key assemblies or other broadly related arrangements being the following, listed in patent number order in the case of the U.S. patents:
U.S. Pat. No. 4,200,227--Lemelson (1980); U.S. Pat. No. 4,257,030--Bruhin et al (1981); U.S. Pat. No. 4,287,735--Brunken et al (1981); U.S. Pat. No. 4,663,952--Gelhard (1987); U.S. Pat. No. 4,858,453--Namazue (1989); U.S. Pat. No. 4,922,736--Tanaka et al (1990); U.S. Pat. No. 4,924,686--Vonlanthen (1990); U.S. Pat. No. 4,947,662--Imedio (1990); U.S. Pat. No. 5,003,801--Stinar et al (1991); U.S. Pat. No. 5,038,590--Sawyer (U.S. Pat. No. 5,083,362--Edgar et al (1992); U.S. Pat. No. 5,156,032--Edgar (1992); U.S. Pat. No. 5,195,341--Nieuwkoop (1993); U.S. Pat. No. 5,307,658--Kokubu et al (1994); U.S. Pat. No. 5,311,757--Spahn (1994); U.S. Pat. No. 5,337,588--Chhatwal (1994); U.S. Pat. No. 5,433,096--Janssen et al (1995); U.S. Pat. No. 5,461,386--Knebelkamp (1995); U.S. Pat. No. 5,469,727--Spahn et al (1995); U.S. Pat. No. 5,532,522--Dietz et al (1996); U.S. Pat. No. 5,561,420--Kleefeldt et al (1996); U.S. Pat. No. 5,561,430--Knebelkamp (1996); and U.S. Pat. No. 5,632,168--Yano (1997).
Also, PCT International Publication No. WO 87/00234 published Jan. 15, 1987; European Patent Office published summary of a German-language application filed Jun. 26, 1991, claiming priority as of Dec. 22, 1989, and identified as Veroffentichungsnummer: 0 434 176 A1; Japanese Patent Application Publication Nos. 2-164647 (1990) and 4-11179 (1992); and UK Patent Application GB 2 155 988 A published on Oct. 2, 1985.