| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively set the efficiency of transmission power to be maximum by proofreading a transceiver based on a proofread signal which a transponder generates and charging it with a charging pulse transmitted from the transceiver. SOLUTION: A passive robbery preventing device 10 is provided with an ignition key 12 containing the transponder inside. When a transceiver 16 learns that the ignition key 12 is inserted into a steering column for starting a vehicle, the transceiver sends a power signal for charging the transponder through an antenna 18 for making the transponder identify it. When a signal 20 sent from the transponder does not correspond to that stored in a control module 24, the control module 24 does not send a starting instruction to an electronic engine control module 26. Thus, the efficiency of transmission power is made maximum without unnecessary power. |
