Patent ID: 9607460
Date: 2017-03-28
CPC Classifications: G07C

Claim:
1. A smart entry system that detects whether or not a mobile device is present within a first transmission area set outside of a vehicle, the smart entry system comprising: a communication section that transmits, with a first cyclic period, a first electromagnetic wave, generating the first transmission area, to outside of the vehicle and receives from the mobile device a response to the first electromagnetic wave; and a control device that determines, based on presence/absence of the response from the mobile device, whether the mobile device is present within the first transmission area, upon determination that the mobile device has continued to be present within the first transmission area for a predetermined time or over, the control device lowers first transmitter power output of the first electromagnetic wave to be transmitted from the communication section to second transmitter power output of the first electromagnetic wave so that the first transmission area is narrowed to a second transmission area until no more response is received from the mobile device, then, the communication section not only transmits the first electromagnetic wave having the second transmitter power output and generating the second transmission area but also transmits, with a second cyclic period longer than the first cyclic period, a second electromagnetic wave, the second electromagnetic wave has the first transmitter power output and generates the first transmission area which is not narrowed, and when no response to the second electromagnetic wave transmitted with the second cyclic period is received from the mobile device, the communication section transmits again, with the first cyclic period, the first electromagnetic wave, the first electromagnetic wave has the first transmitter power output and generates the first transmission area, the first transmitter power output is not lowered and the first transmission area is not narrowed.