Patent ID: 7279807

Claim:
An electronic key system for a vehicle comprising a controller mounted in the vehicle and a portable transmitter carried by a user of the vehicle, the vehicle containing a locking unit which locks the vehicle so that the vehicle cannot be used until a lock release command is received, the portable transmitter comprising a transmitter unit that outputs a request signal to the controller in response to an operation input by the user, and wherein the controller comprises: a receiving circuit that receives the request signal from the portable transmitter; a receiver which receives via the receiving circuit the request signal from the portable transmitter in response to an ON operation of a switch which detects that the user has boarded the vehicle; a drive unit which outputs a lock release command to the locking unit when the request signal is compared and judged to be a request from the user; an interrupting unit which interrupts, if the vehicle is not started for a specified period of time, a supply of power to the receiving circuit inside the controller; an interrupting unit controller which permits the interrupting unit to provide power to the receiving circuit in response to an ON operation of the switch; a switching unit configured to interrupt a supply of power to the transmitter unit and receiving circuit, and a switching unit controller which permits the switching unit to provide: a normal supply of power to the transmitter unit and the receiving circuit in response to the ON operation of the switch when the user boards the vehicle, a normal supply of power to the transmitter unit and the receiving circuit for a specified period of time if the vehicle is turned off, and no power to the transmitter unit and the receiving circuit for an indefinite period of time after the specified period of time has elapsed.