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:
Dec. 01, 1998
Filed:
Nov. 15, 1996
Tokai-Rika-Denki-Seisakusho Kabushiki Kaisha, Niwa, JP;
Abstract
The invention relates to a transmission-reception system, particularly a transmitter-receiver device contained in the bow of an ignition key. When a resonance circuit receives a carrier wave signal from a transmission-reception ECU of a motor vehicle, a microcomputer is switched to an active state by the output of a power circuit that smoothes and rectifies the carrier wave signal. A detector circuit discriminates an enquiry signal supplied together with the carrier wave signal through the resonance circuit portion, and outputs the signal to the microcomputer. In response to the enquiry signal together with random number data, the activated microcomputer changes the bit length of an identification code stored in an EEPROM, on the basis of the received random number data and a predetermined function, and performs the on-off control of an FET of a modulating circuit in a mode corresponding to the bit length-changed identification code. The microcomputer thus performs control to send back an enciphered answer signal to the transmission-reception ECU.