Patent ID: 7629876

Claim:
A wireless key comprising: a built-in battery as a power supply; a polling radio wave receiver circuit that operates with the built-in battery to receive a polling radio wave for wireless key search and authentication from a subject body to be controlled; a lock/unlock instruction radio wave transmitter circuit that transmits a lock/unlock instruction radio wave to instruct locking/unlocking of a door of the subject body; a manipulation device that gives a trigger of transmission of the lock/unlock instruction radio wave to the lock/unlock instruction radio wave transmitter circuit; and a control circuit having mode changeover means for changing over an operation mode of the polling radio wave receiver circuit and the lock/unlock instruction radio wave transmitter circuit between a power saving mode and a full power mode, the power saving mode permitting transmission of the lock/unlock instruction radio wave by the lock/unlock instruction radio wave transmitter circuit and stopping reception of the polling radio wave by the polling radio wave receiver circuit, and the full power mode permitting the transmission of the lock/unlock instruction radio wave by the lock/unlock instruction radio wave transmitter circuit and continuing the reception of the polling radio wave by the polling radio wave receiver circuit.