Reader/writer and communication method thereof

• US 7,487,921 B2
• Filed: 08/28/2006
• Issued: 02/10/2009
• Est. Priority Date: 09/05/2005
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications Japan Incorporated (Sony Group Corp.)
• Inventors: Ito, Kunitaka, Shimizu, Kanjiro, Takahashi, Toshiyuki
• Primary Examiner(s): LE, UYEN CHAU N
• Application Number:
  US11/510,694
• Publication Number:
  US 20070051809A1
• Time in Patent Office: 897 Days
• Field of Search: 235/441, 235/451, 235/492, 235/472.02
• US Class Current: 235/492
• 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 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10326 the antenna being of the very-near field type, e.g. capacitive

Abstract

A reader/writer is provided. The reader/writer performing radio communication with a radio communication terminal in close proximity thereto, includes: an antenna which transmits a carrier wave of a predetermined frequency and which receives a composite wave of the carrier wave and a modulated signal of the carrier wave transmitted from the radio communication terminal; a demodulating unit which demodulates the composite wave received by the antenna; a judging unit which judges whether or not it is difficult to detect a modulated component included in the composite wave received by the antenna when the radio communication terminal is in close proximity; and a carrier-wave control unit which reduces a component of the carrier wave input into the demodulating unit when the judging unit judges that it is difficult to detect the modulated component.

Claims

1. A reader/writer performing radio communication with a radio communication terminal in close proximity thereto, comprising:

an antenna for transmitting a carrier wave of a predetermined frequency and receiving a composite wave of said carrier wave and a modulated signal of a signal having the frequency identical to that of said carrier wave transmitted from said radio communication terminal;

a demodulating unit for demodulating the composite wave received by said antenna;

a judging unit for judging whether a null state has occurred when said radio communication terminal is in close proximity; and

a carrier-wave control unit having an auxiliary antenna provided in the proximity of said antenna for reducing a component of said carrier wave input into said demodulating unit by wirelessly transmitting a signal of a reverse phase to said carrier wave from the auxiliary antenna when said judging unit judges that the null state has occurred.

2. A reader/writer according to claim 1,

wherein the composite wave received by said antenna is a composite wave including a signal amplitude-modulated by said radio communication terminal, and

a judgment that the null state has occurred is made by judging that a change in amplitude of said composite wave is not detected in the null state.

3. A reader/writer according to claim 2,

wherein said judgment is performed based on voltages at both ends of a resistor to which said composite wave received is supplied.

4. A communication method of a reader/writer performing radio communication with a radio communication terminal in close proximity thereto, comprising:

transmitting a carrier wave of a predetermined frequency;

receiving a composite wave of said carrier wave and a modulated signal of said carrier wave transmitted from said radio communication terminal;

demodulating said composite wave received;

judging whether a null state has occurred when said radio communication terminal is in close proximity; and

wirelessly transmitting a signal of a reverse phase to said carrier wave from an auxiliary antenna when judged that the null state has occurred.

5. A reader/writer performing radio communication with a radio communication terminal in close proximity thereto, comprising:

an antenna for transmitting a carrier wave of a predetermined frequency and receiving a composite wave of said carrier wave and an amplitude-modulated signal of a signal having the frequency identical to that of said carrier wave transmitted from said radio communication terminal;

a demodulating unit for demodulating the composite wave received by said antenna;

a judging unit having a resistor for judging whether a null state has occurred based on voltages at both ends of a resistor to which said composite wave received is supplied when said radio communication terminal is in close proximity; and

a carrier-wave control unit for reducing a component of said carrier wave input into said demodulating unit when said judging unit judges that the null state has occurred.

6. A reader/writer according to claim 5,

wherein said carrier-wave control unit reduces the component of said carrier wave input into said demodulating unit by wirelessly transmitting a signal of a reverse phase to said carrier wave from an auxiliary antenna provided in the proximity of said antenna.