Hitachi Maxell, Limited

Ntt Data Communications Systems Corporation

Nii Data Communications Systems Corporation

Yosuke Katayama

Takashi Takeuchi

Wasao Takasugi

Toshiharu Ieki

A non-contact IC card communication in which power consumption of a driver of a reader/writer is reduced and the size of a power supply circuit for operating the driver is made small. The driver has a low output impedance. A current detecting circuit including a detecting coil magnetically coupled with a transceiver coil of the reader/writer through a magnetic coiling element and a resistor detects a current which flows through the transceiver coil. A voltage drop to be detected is small and is approximately constant for a variation of the transceiver coil current. When data is read from an IC card, a load of the driver is changed. The driver drives the transceiver coil in a constant voltage fashion even if a current flowing through the transceiver coil changes due to the change in load. Input voltages of a rectifying/smoothing circuit and a regulator in the IC card become approximately constant. As a result, the amplitude of a high frequency output voltage of the driver can be made small. Also, a high frequency signal current sent from a reader/writer is subjected to double modulation including amplitude modulation by card data and modulation by second information, such as information indicative of the abnormality of an IC card, in synchronism with a timing at which data transmission between the reader/writer and the card is made, and the second information is extracted by the reader/writer.

Non-contact, electromagnetically coupled transmission and receiving

An IC recording medium for executing data transmission/reception without contact with a reader/writer. The non-contact IC recording medium comprises a first circuit for detecting a synchronization (sync) signal sent from a reader/writer to generate a first clock signal, a second circuit for generating a second clock signal having a predetermined frequency relationship with the clock signal for driving the data processing in a signal processing circuit incorporated therein, a third circuit for writing m (where m is an integer of 2 of greater) number items of transfer information output from the signal processing circuit using the second clock signal and reading them using the first clock signal, a fourth circuit for creating an interruption signal from the start bit in at least the first transfer information in the m number of items of transfer information to place the subsequent m number of items of transfer information in a wait state, and a fifth circuit for releasing the wait state of the subsequent m number of items of information by the fourth means.

Non-contact IC recording medium

A semiconductor card which at least comprises a printed circuit board, a volatile memory element mounted on the printed circuit board, a battery electrically connected with the printed board for serving to back up the volatile memory element, an input/output interface portion mounted on the printed board for communication with an external device, and a sealant or sealing layer made of a thermosetting resin in which the printed circuit board, volatile memory element and interface portion are integrally embedded, the semiconductor card further including a battery receiving portion formed of a thermoplastic resin having a space for receiving the battery therein, and a battery cover formed of a thermoplastic resin so as to serve to close an opening in the battery receiving portion, the battery receiving portion being fixed to the printed circuit board and integrally embedded in the sealing layer together with the other stated elements on the printed circuit board, and the battery receiving portion is joined after receiving the battery therein with a battery cover by means of welding.

Growing community of inventors

Toride, Japan

Yosuke Katayama