| 摘要 |
<p>PROBLEM TO BE SOLVED: To turn on a power supply only when the communication is necessary and to secure the high battery saving performance by generating the electromotive force from a received line of magnetic force to turn on the power switch of a battery and then transmitting an ID code by radio to turn off the battery power switch. SOLUTION: An ID card device 30 receives the line of magnetic force of a line-of-magnetic-force generator 11 of an interrogator 20, generates the weak electromotive force via a lineof-magnetic-force detector 3 and turns on a main switch 2 of a power supply battery 1 to supply the current to each circuit part of the device 30 that requires the power. Then, a control part 5 starts its control operation to read out an ID card and modulates the card contents to transmit them to an antenna 12 of the device 20 as radio signals through an antenna 8. When the device 30 finishes its operation necessary for transmission of the radio signals, the part 5 recognizes the end of transmission and other control operations and turn off the switch 2 to cut off the power supply to the device 30.</p> |
