| 摘要 |
PROBLEM TO BE SOLVED: To prolong the life of a battery and to optimize the timing of transmission of a detection signal to a reception part by providing a timer means, a counting means, and a restricting means which stops sending a radio signal only for a certain time when the counted value decreases below a certain value. SOLUTION: The transmitter is equipped with a storage timer 23 which operates after a radio wave is sent out and measures the time thereafter until the detection signal is received from a sensor part 1, a counting circuit 22 which increases the count value as the measured time of the timer 23 increases, and a restriction timer 24 which decrease the count value of the counting circuit 22 each time the detection signal is inputted from the sensor part 1 and starts measuring the time after the counted value reaches zero. Then a control part 21 while monitoring the input state of the detection signal from the sensor part 1, the count value of the counting circuit 22, and the state of the restriction timer 24 controls the radio wave transmission. Therefore, the radio wave transmission is limited on the side of a transmission part 2 and battery consumption is prevented. |
