| 摘要 |
PROBLEM TO BE SOLVED: To increase the effective life of a power supply. SOLUTION: A measuring unit 2 which is not easy to approach is provided with a power supply 26. The power supply 26 energizes various elements, and, especially, it converts an analog measured signal into digital measured data so as to be stored. The measured data of the measuring unit 2 is transmitted to a base station 1 as soon as the base station 1 approaches the measuring unit 2 so as to send out a signal. In order to minimize the load of the power supply 26, the electric power of the power supply 26 is not supplied to a transmitter 30 so that the measured data is transmitted to the base station 1 from the measuring unit 2, and, instead of it, a signal which is transmitted by the base station 1 is used. In this case, in the measuring unit 2, a voltage which energizes the transmitter 30 can be taken out from the signal. In addition, the base station 1 and the measuring unit 2 are inductively coupled by a tuning circuit, an impedance is connected to the tuning circuit at the measuring unit 2 via a switch, and the switch can be controlled by the measured data. A change in the impedance can be evaluated by the base station 1. The signal which is transmitted by the base station 1 can be used to recharge the power supply 26 inside the measuring unit 2. |
