Storage medium system which uses a contactless memory card

• US 6,088,741 A
• Filed: 03/09/1998
• Issued: 07/11/2000
• Est. Priority Date: 05/09/1996
• Status: Expired due to Fees

• Current Assignee: Citizen Holdings Co., Ltd.
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Murata, Mitsuhiro
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): TZENG, FRED
• Application Number:
  US08/981,785
• Time in Patent Office: 855 Days
• Field of Search: 711/115, 711/170, 340/10.3, 340/10.51, 235/449, 600/508, 600/509, 375/279, 710/20, 710/129
• US Class Current: 710/20
• 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

Abstract

In a contactless memory card system, a means is provided for sending a transmission wait request signal to the memory card when yet-to-be-passed received data remains in both the serial data receiving circuit and received data buffer via an electromagnetic coupling interface section, thereby preventing overrun errors even when the reading by a microcomputer of reader/writer received data is slow.

Claims

1. A storage medium system which uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via electromagnetic coupling interface sections which include respective coils that serve for both transmitting and receiving, said reader/writer comprising:

a data receiving circuit that receives said data sent from the memory card side via said electromagnetic coupling interface section and converts said data to parallel data;

a received data buffer that receives and stores already-received parallel data that had been passed by said data receiving circuit;

a receiving control circuit which, in a condition in which there is already-received data remaining in both said data receiving circuit and said received data buffer, outputs a transmission wait request signal to said memory card; and

a transmitting modulation circuit which receives said transmission wait request signal and controls said electromagnetic coupling interface section so as to be in a prescribed transmission modulation condition.

2. A storage medium system that uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via electromagnetic coupling interface sections which include respective coils that serve for both transmitting and receiving, said memory card side comprising:

a data transmitting circuit that sends start-stop synchronized serial data to said reader/writer via said electromagnetic coupling interface section;

means for detecting, during an interval between each transmission of said start-stop synchronized serial data, the presence or lack of a transmission wait request signal sent from said reader/writer through said electromagnetic coupling interface section; and

a transmitting control circuit which, when once said detecting means detects said transmission wait request signal, causes said data transmitting circuit to wait to transfer the next data to said data transmitting circuit, at least until said transmission wait request signal is cleared.

3. A storage medium system that uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via electromagnetic coupling interface section which include respective coils that serve for both transmitting and receiving, said reader/writer side comprising:

a data receiving circuit that receives said data sent from said memory card side via said electromagnetic coupling interface section and converts said data to parallel data;

a received data buffer which receives and stores already-received parallel data in a prescribed bit units, that has been passed by said data receiving circuit;

a receiving control circuit which, in a condition in which there is already-received data that has yet to be passed remaining in both said data receiving circuit and said received data buffer, outputs a transmission wait request signal to said memory card; and

a transmission modulation circuit which receives said transmission wait request signal and controls said electromagnetic coupling section as to be in a prescribed transmission modulation condition, and said memory card side comprising;

a data transmitting circuit that transmits start-stop synchronized serial data via said electromagnetic coupling interface section in prescribed bit units to said reader/writer;

means for detecting, during an interval between each transmission of said start-stop synchronized serial data in prescribed bit units, the presence or lack of said transmission wait request signal sent from said reader/writer through said electromagnetic coupling interface section; and

a transmitting control circuit which, when once said detecting means detects said transmission wait request signal, causes said data transmitting circuit to wait to transfer the next data to said data transmitting circuit, at least until said transmission wait signal is cleared.

4. A storage medium system that uses a contactless memory card according to claim 3, wherein said electromagnetic coupling interface section comprises a first electromagnetic coupling interface section and a second electromagnetic coupling interface section.

5. A storage medium system that uses a contactless memory card according to claim 4, wherein said data receiving circuit on said reader/writer side comprises a first data receiving circuit and a second data receiving circuit and wherein said data transmitting circuit of said memory card side comprises a first data transmitting circuit and a second data transmitting circuit.

6. A storage medium system that uses a contactless memory card according to claim 5, wherein said data in prescribed bit units is divided into a first data group and a second data group, said first and second data groups being separately communicated via said first and second electromagnetic coupling interface sections, respectively.

7. A storage medium system that uses a contactless memory card according to claim 6, wherein said first data group includes a start bit and a stop bit, and said second data group includes a parity bit and a stop bit, and further wherein said reader/writer side is configured so as to send a transmission wait request signal to said memory card via said second electromagnetic coupling interface section.

8. A storage medium system that uses a contactless memory card according to claim 3, wherein said electromagnetic coupling interface section comprises a first electromagnetic coupling interface section and a second electromagnetic coupling interface section for the purpose of dividing said data with a prescribed bit units into two groups and transmitting and receiving thereof, and further wherein said first electromagnetic coupling interface section includes a function of sending a start bit when start-stop synchronized serial data is transmitted from said reader/writer to said memory card, and wherein said second electromagnetic coupling interface section includes a function of sending a transmission wait request signal from said reader/writer to said memory card.

9. A storage medium system that uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via an electromagnetic coupling interface sections which includes respective coils that serve both for transmitting and receiving, said memory card side comprising:

an antenna of said electromagnetic coupling interface section that is an LC resonant circuit;

a transmitted signal forming circuit which forms a transmitted signal by means of a single-shot signal in response to the contents of said data to be transmitted;

a transmission driving circuit which drives said LC resonant circuit in response to said transmitted signal;

a resonance control circuit which is connected in parallel with said LC resonant circuit; and

a control signal forming circuit which forms a control signal having a prescribed phase relationship with respect to the timing of the output of said transmitted signal, said control signal controlling a switching element that is part of said resonance control circuit so as to promote attenuation of oscillation in said LC resonant circuit.

10. A storage medium system that uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via electromagnetic coupling interface sections which include respective coils that serve both for transmitting and receiving, said electromagnetic coupling interface section comprising a plurality of electromagnetic coupling interface sections, an antenna of each of said plurality of electromagnetic coupling interface sections in said memory card side being an LC resonant circuit, and said memory card side comprising:

a transmitted signal forming circuit which forms a transmitted signal by means of a single-shot signal in response to the contents of said data to be transmitted and

a transmission driving circuit which drives said LC resonant circuit in response to said transmitted signal, said transmitted signal forming circuit and said transmission driving circuit being provide for each LC resonant circuit of said plurality of LC resonant circuits,

and wherein each transmitted signal forming circuit forms said transmitted signals with mutually different timing, so that the timings of the driving of each said transmission driving circuit are mutually skewed.

11. A storage medium system that uses a contactless memory card and a card reader/writer that perform transfer of information that is start-stop synchronized serial data via an electromagnetic coupling interface sections which includes respective coils that serve both for transmitting and receiving, said electromagnetic coupling interface section comprising a first electromagnetic coupling interface section and a second electromagnetic coupling interface section, wherein at said memory card side an antenna of each of said first and second electromagnetic coupling interface sections is an LC resonant circuit in said memory card side, and further wherein said memory card side comprising:

a transmitted signal forming circuit which forms a transmitted signal by means of a single-shot signal in response to the contents of said data to be transmitted;

a transmission driving circuit which drives said LC resonant circuit in response to said transmitted signal;

a resonance control circuit which is connected in parallel to said LC resonant circuit; and

a control signal forming circuit which forms a control signal having a prescribed phase relationship with respect to the timing of the output of said transmitted signal,

said transmitted signal forming circuit, said transmission driving circuit, said resonance control circuit, and said transmission circuit being provided for both said first and second LC resonant circuits, so that each of the data transmitted signal forming circuit forming said transmission signal with a different timing from each other whereby the drive timing of each transmission driving circuit is mutually skewed, each of said control signal forming circuit minimally outputting a control signal with a timing at least when the other side'"'"'s LC resonant circuit is driven, said control signal controlling a switching element of said resonance control circuit so that attenuation of oscillations in said LC resonant circuit is promoted.

12. A storage medium system that uses a contactless memory card according to claim 11, wherein said resonance control circuit is formed by a series circuit of an FET provided as a switching element and a resistance.

13. A storage medium system that uses a contactless memory card according to claim 11, wherein said LC resonant circuit is a parallel resonant circuit, and wherein the transmitted signal pulse width is 1/8 of a bit time width or less and further wherein the resonance control signal pulse width is between 1/4 and 5/8 of the bit time width.