IC card device for managing system

• US 5,640,003 A
• Filed: 06/20/1995
• Issued: 06/17/1997
• Est. Priority Date: 07/26/1994
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Makino, Tadayori
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Le, Thien Minh
• Application Number:
  US08/492,800
• Time in Patent Office: 728 Days
• Field of Search: 235/380, 235/384, 235/375, 235/491, 235/492, 455/51.4, 455/88, 455/38.1, 342/44, 342/42, 342/51, 340/825.34
• US Class Current: 235/491
• 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

Abstract

An IC card device capable of transmitting identification data to an inquiring unit without involving interference even when a plurality of IC card devices stay in the vicinity of the inquiring unit over a certain time. As the IC card device approaches the inquiring unit, the field intensity of a signal received by a receiver circuit incorporated in the IC card device increases. When it is determined that the field intensity exceeds a preset threshold level, a reception level determination circuit reads out identification data from a memory. A transmitter circuit transmits repeatedly the identification data signal to the inquiring unit. When the number of times the identification data is transmitted reaches a preset number, a counter stops the transmitting operation of the transmitter circuit. When it is determined by a reception level determination circuit that the field intensity exceeds the preset threshold value, a timer causes the receiver circuit to stop reception of the signal transmitted from the inquiring unit for a predetermined period.

Claims

1. An IC card device comprising:

receiver means for receiving a radio signal transmitted to said IC card device to thereby output a reception signal;

a memory in which data is previously stored;

reception level determination means for determining a level of said reception signal output from said receiver means and reading out the data stored in said memory to output said data when determining that said level of said reception signal output from said receiver means exceeds a predetermined threshold level;

transmitter means for repeatedly transmitting the data output from said reception level determination means;

event counter means for counting a number of times said data is transmitted from said transmitter means to thereby stop a transmitting operation of said transmitter means when said number of times reaches a preset number; and

timer means for stopping receiving operation of said receiver means for a predetermined time period when said reception level determination means determines that a level of the reception signal output from said receiver means exceeds a predetermined threshold level.

2. An IC card device according to claim 1, wherein:

said reception level determination means sorts said level of said reception signal output from said receiver means into one of plural classes; and

said event counter means sets said preset number in accordance with a class to which the level of said reception signal belongs.

3. An IC card device according to claim 2, wherein:

said event counter means sets said preset number such that the number of times said data is transmitted from said transmitter means becomes smaller for the class in which the level of said reception signal is higher.