NONCONTACT COMMUNICATION MEDIUM AND NONCONTACT COMMUNICATION SYSTEM

摘要

A noncontact communication medium enabling communication over a predetermined distance even if such noncontact communication media are stacked. The output of a resonance circuit (60) electromagnetically coupled to an external communication device is rectified by a power supply circuit (62) and taken out. The output voltage V is monitored by a switch control circuit (61). If the output voltage V exceeds a threshold Vth1, a switch element (SW) is turned on. If the output voltage V further increases, a power supply switch element (PSW) is turned on. If the output voltage V lowers below the threshold Vth1, the switch element (SW) is turned off. When two noncontact IC card (6) in use are stacked, the switch element (SW) of one of the cards is on, and the witch element (SW) of the other is off. In this state, both cards can be used for communication.