| 摘要 |
<p>PURPOSE: To guarantee the detection of the blanking period of an alternating electromagnetic field for transmitting energy even when a supply voltage is small. CONSTITUTION: Energy is supplied through an alternating electromagnetic field to an IC card 1 by a writing/reading device. Bi-directional data transmission is operated by the modulation of the alternating electromagnetic field for transmitting a power. This IC card 1 is provided with an antenna coil 2 which receives an alternating electromagnetic field, an inputting circuit 3 which generates a supply voltage from coil currents, and a voltage detector 4 which detects the blanking period in the alternating electromagnetic field. The voltage detector 4 compares both voltages impressed to coil edges, and supplies an output signal when the both voltages are substantially the same size for a longer time than a specific time.</p> |
