Patent ID: 6173899
Filing Date: 2001-01-16
Classification: G06K,H01F

Abstract:
A method for contactless energy transmission and data exchange between a host terminal and integrated circuit IC card, which is powered via an energy-transmitting alternating field at a different frequencies which are modulated with data signal to provide bidirectional data transfer, comprising the steps of:the remote bidirectional data transmission and energy transfer into the IC card at first, lowest frequency, utilizing the inductive coupling between a terminal transmitting-receiving coil and an IC card transmitting-receiving coil while IC card is separated from terminal,the close coupling bidirectional data transmission and energy transfer into the IC card at second frequency, higher than first frequency, utilizing the galvanically contactless capacitive coupling between terminal capacitive pads and IC card capacitive pads while IC card is attached closely to the terminal,wherein first frequency is designed to be a frequency of a parallel resonant circuit combined by parallel alignment of an IC card inductive coil and a distributed capacitance of IC card capacitive pads,wherein second frequency is designed to be a frequency of a series resonant circuit associated with additional inductor of terminal and joint capacitance of a terminal capacitive pads with the IC card capacitive pads, when card is attached closely to terminal, andthe second frequency is selected to be as higher than first frequency where an equivalent impedance of IC card inductive coil is significantly large to load the series resonant circuit combined by serial alignment of joint capacitance created by mating of terminal capacitive pads with IC card capacitive pads with an additional inductance of terminal when IC card is attached closely to terminal.