| 摘要 |
<p>PROBLEM TO BE SOLVED: To appropriately respond to the field of different intensity by providing a high field circuit, a low field circuit, and an intermediate field circuit together with different sub circuits to modulate the current according to the condition of the field intensity. SOLUTION: An improved attenuation modulation circuit 140 receives the energy transmitted from an antenna of a transmitter/receiver, and generates the specific recognition signal in a transponder. The improved attenuation modulation circuit 140 is provided with high field intensity circuits 152, 160, 174 to protect the transponder from the overvoltage using a voltage limiter 132 while the power is supplied to the transponder. The low fleld intensity circuit 152 starts only a minimum number of circuit groups to supply the maximum available power to the transponder. The intermediate field intensity circuits 152, 160 increase the field intensity in the transponder to secure the current of sufficient quantity to appropriate modulation using only the transponder circuit elements of the intermediate quantity.</p> |
