Noncontacting IC card supplied with power from an outside source

• US 4,962,485 A
• Filed: 02/14/1989
• Issued: 10/09/1990
• Est. Priority Date: 02/16/1988
• Status: Expired due to Fees

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Kato, Yoshiaki, Ishikawa, Hiromi, Yuyama, Harumi, Ojima, Tutomu
• Primary Examiner(s): Moffitt, James W.
• Application Number:
  US07/309,880
• Time in Patent Office: 602 Days
• Field of Search: 365/228, 365/229
• US Class Current: 365/229
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• 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: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR
• CPC Class Codes: G11C 5/143 Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels G11C5/148 takes precedence; Switching between alternative supplies G11C5/141 takes precedence

Abstract

An IC card such as cash card is disclosed. The IC card has a RAM, a control circuit for controlling access to the RAM, and a power supply circuit receiving outside energy and supplying power to the RAM and the control circuit. A first voltage detector produces a starting output when supply voltage of the power exceeds a predetermined first reference voltage. A second voltage detector produces a control signal when the supply voltage exceeds a predetermined second reference voltage, which is higher than the first reference voltage. An AND gate is provided to produce a RAM control signal for operating the RAM when the starting signal and the control signal are applied thereto.

Claims

1. A non-contact IC card having a RAM, a control circuit for controlling access to the RAM, a power supply circuit, for electro-magnetic non-contact connection to an outside source for receiving outside energy and converting it to electric energy to supply power to the RAM and the control circuit, a backup battery for maintaining data stored in the RAM, and input/output device for a reader/writer, comprising:

first voltage detection means, connected to the power supply circuit, for producing a starting signal for starting the control circuit when supply voltage from said power supply circuit exceeds a predetermined first reference voltage;

second voltage detection means, connected to the power supply circuit, for producing a control signal when the supply voltage from the power supply circuit exceeds a predetermined second reference voltage, which is greater than the predetermined first reference voltage;

gate means, responsive to both the starting signal and the control signal, for producing a RAM control signal for operating the RAM.

2. The IC card according to claim 1 wherein each of first and second voltage detection means comprises a comparison means for comparing the supply voltage with a predetermined reference voltage.

3. The IC card according to claim 1 wherein the gate means is an AND gate.

4. A non-contact IC card having a RAM, a control circuit producing an access signal for operating the RAM, and a backup battery for maintaining data stored in the RAM, comprising:

power supply means, including a coil electromagnetically connected to a coil of an outside reader/writer, for producing an alternating current from said outside reader/writer and for converting the alternating current to a direct current thereby creating an input supply voltage;

first voltage detection means, connected to the power supply means, for producing a starting signal for starting operation of the control circuit when the input supply voltage exceeds a predetermined first reference voltage;

second voltage detection means, connected to the power supply means, for producing a control signal when the supply voltage exceeds a predetermined second reference voltage, which is greater than the first reference voltage;

gate means, connected to the control circuit and the RAM, for producing a RAM control signal to operate and access the RAM in response to both said starting signal and said control signal.

5. The IC card of claim 4, further comprising:

current supply circuit having a first diode connected to the backup battery and a second diode connected to the output of the power supply means, the diodes being further connected to the gate means and the RAM for controlling operation thereof.

6. The IC card of claim 4, further comprising:

transmitter coil, connected to said RAM, for applying data stored in the RAM to the reader/writer during a read operation; and

receiving coil, connected to said RAM, for receiving data from the reader/writer to the RAM during a write operation.

7. A non-contact IC card for electromagnetic connection to an external read and write device, comprising:

memory means, for storing data written from said external read and write device for outputting data read by said external read and write device;

power supply means, electromagnetically connected to said external read and write device, for receiving a signal from said external read and write device and outputting a corresponding supply voltage;

first detection means, operatively connected to said power supply means, for receiving said output supply voltage and for outputting a first control signal upon said output supply voltage exceeding a first predetermined threshold;

control means, operatively connected to said first detection means for outputting a second control signal, said second control signal being output upon receiving said first control signal from said first detection means;

second detection means, operatively connected to said power supply means, for receiving said output supply voltage and for outputting a third control signal upon said output supply voltage exceeding a second predetermined threshold greater than said first predetermined threshold; and

gate means, operatively connected to said control means, memory means, and second detection means, for outputting a memory access signal to said memory means to allow writing of data from said external read and write device to said memory means and reading of data by said external read and write device from said memory means, said memory access signal being output upon said gate means receiving both said second and third control signals.

8. The non-contact I.C. card of claim 7, wherein said second control signal output by said control means is a signal corresponding to a program for reading and writing data to and from said memory means.

9. The non-contact IC of claim 7, wherein said gate means is an AND gate.

10. A method of reading data from and writing data to a non-contact I.C. card, to and from an electromagnetically connected external read and write device, respectively, the method comprising the steps of:

(a) receiving a signal from the external read and write device and supplying a supply voltage to the I.C. card;

(b) detecting the supply voltage and outputting a first control signal upon the supply voltage exceeding a first predetermined value;

(c) outputting a second control signal upon receiving the first control signal;

(d) detecting the supply voltage and outputting a third control signal upon the supply voltage exceeding a second predetermined value greater than the first predetermined value; and

(e) outputting a memory access signal to allow writing of data from the external read and write device to the I.C. card and reading of data by the external read and write device from the I.C. card, the memory access signal being output upon detecting that both the second and third control signals have been output.

11. The method of claim 10, wherein the second contact signal is a signal corresponding to a program within the I.C. card for reading and writing of data.

12. The method of claim 10, wherein a memory within the IC card stores data written from the external read and write device and data read by the external read and write device.