Noncontact card and card system

• US 5,604,342 A
• Filed: 01/20/1995
• Issued: 02/18/1997
• Est. Priority Date: 03/30/1994
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Electric Semiconductor Software Company Limited
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Semiconductor Software Company Limited
• Inventors: Fujioka, Shuzo
• Primary Examiner(s): SHEPPERD, JOHN W
• Application Number:
  US08/375,981
• Time in Patent Office: 760 Days
• Field of Search: 235/435, 235/375, 235/380, 235/449
• US Class Current: 235/435
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10297 arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 cryptographic protocols H04L9/00; network security protocols H04L63/00; real-time communication protocols in data switching networks H04L65/00; network protocols for data switching network services H04L67/00
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22

Abstract

An IC card reader/writer includes a control unit incorporating a central processing unit, read only memory, and random access memory. In addition, the reader/writer includes a UART, a sending circuit for modulating a digital signal received from the UART, transmitting and receiving antennas, and a receiving circuit for demodulating received signals. The control unit controls the IC card reader/writer by setting an interval between a trigger signal and a start flag at the time of data transmission equal in duration to at least one frame of data, for example, eight bits of data. In a specific embodiment, the trigger signal may be followed by eight bits of 00_H, followed by a start flag and eight bits of data 5A_H, followed by a data stream including desired information.

Claims

1. A card reader/writer comprising:

a UART for converting a digital signal in serial form into parallel form and vice versa;

a send circuit for modulating a digital signal in serial form from said UART and converting it into a send electrical signal;

a transmitting antenna for transmitting the send electrical signal as a radio wave;

a receiving antenna for converting a received radio wave into a received electrical signal;

a receive circuit for demodulating a received electrical signal and converting it into a digital signal; and

a control unit for controlling said card reader/writer and for setting an interval between a trigger signal and a start flag to at least one frame.

2. The card reader/writer according to claim 1, wherein the control unit inserts dummy data between said trigger signal and the start flag.

3. The card reader/writer according to claim 2, wherein said transmitting antenna is a series resonance circuit.

4. The card reader/writer according to claim 3, further comprising a switching circuit connected between said receiving antenna and said receive circuit for disconnecting them during transmission.

5. The card reader/writer according to claim 4, wherein said switching circuit disconnects said receiving antenna and said receive circuit with a timing, that prevents switching noise from being transmitted to said receive circuit.