| 摘要 |
PROBLEM TO BE SOLVED: To minimize the reception of unnecessary electric power and to reduce adverse influence of heat, etc., on an internal circuit by transmitting the distance between the coils of a reader/writer and a card to a user with visible light by changing the light emission of a light emitting diode according to the distance between the coils. SOLUTION: A power receiving coil 1 receives electric power and a signal from a transmitter receiver as a master machine. The received electric power component is rectified by a rectifying circuit 2 and transmitted to a constant- voltage circuit 4 and a voltage detecting circuit 3. The DC current which is made constant in voltage by the constant-voltage circuit 4 is supplied as the electric power for a control circuit 5, a frequency detecting circuit 6, etc. The DC current transmitted to the voltage detecting circuit 3, on the other hand, has its voltage compared and is classified into a low level, an optimum level, and a high level and LEDs 8 to 10 corresponding to the respective levels are turned on. Voltage settings are so made that the card is put too far away for the small level, at an optimum position for the intermediate level, and too close for the large level, and the LEDs are turned on to inform the user of the state. |
