| 摘要 |
<p>PURPOSE:To prevent the forgery of a storage content and the abrasion of the device. CONSTITUTION:A sound-receiving body 3 for sound-receiving a sound wave from an external equipment, the energy of the field of a ultrasonic wave, for example, and an encoding circuit 6 where a previously allocated identification code is stored are provided for the signal generation device 2. A rectifier circuit 4 is connected between the sound-receiving body 3 and the encoding circuit 6, and DC power obtained from the energy of the sound wave is given to the encoding circuit 6. A frequency conversion circuit 5 frequency-divides the AC component of energy and it is given to the encoding circuit 6 as a clock signal. The identification code from the encoding circuit 6 is loaded on the sound wave and a radio wave through a connector 7 so as to transmit it.</p> |
