Ic card

Abstract

Abstract PURPOSE:To prevent the mixing of radio waves for data transmission/reception with other radio waves by providing an IC card for transmitting/receiving data by means of radio waves with plural resonance circuits and a switching circuit for switching the resonator circuit and setting up the resonance frequency of the resonance circuits to the carrier of the radio waves. CONSTITUTION:The IC card is provided with a transmitting/receiving circuit 12a connected to the resonance circuits consisting of a coil 13 and capacitors 14a to 14d. A radio wave from a card reader/writer is inputted to a CPU 12e as a trigger signal through the resonance circuit RF consisting of the coil 13 and the capacitor 14d, the circuit 12a and an I/O circuit 12b to start a CPU 12e. Then, the CPU 12e receives the frequency code of the radio wave and one of the capacitors 14a to 14c is selected by the frequency code through a switch 15a to set up resonance frequency. Then, data are transmitted/received by the frequency. After completing communication, the resonance frequency is reset and a waiting state based on reference frequency is restored.

Inventors

• 👤 Shigeru Furuta
• 👤 茂 古田

Bibliographic Details