| 摘要 |
<p>PURPOSE:To reduce power consumption in the state of suspending a non-contact IC card and to surely communicate by avoiding a point where the field intensity by phasing is reduced. CONSTITUTION:Only in the period in which CPU 21 of the non-contact IC card 20 is in an excited state, a signal OSCC is outputted to an oscillation control circuit 28 and the oscillation operation of an oscillation circuit 27 is permitted. Then, a carrier wave level monitor 29 constantly monitors the reception level of the carrier wave detection circuit for detecting communication possible area entry and in the state where the level is less than a prescribed value, CPU 21 deters communication. A field intensity meter 18 measures the fiele intensity of a reception wave 17 from the non-contact IC card 20, which is received by the reception antenna 14 on the side of a unit 10 on the side of a tollhouse and demodulated by the receiver 15 and in a state where the measured value is less than the prescribed value, tollhouse CPU 11 does not enter a communication sequence.</p> |
