RFID tag and RFID tag communication distance modification method

• US 7,834,743 B2
• Filed: 06/10/2005
• Issued: 11/16/2010
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Niimi, Hiroaki, Tagiri, Satoshi, Usuki, Izumi, Nagata, Minehisa, Kuhara, Shunsuke, Kemi, Shinya
• Primary Examiner(s): Goins; Davetta W
• Assistant Examiner(s): LAI, ANNE VIET NGA
• Application Number:
  US11/628,751
• Publication Number:
  US 20070229278A1
• Time in Patent Office: 1,985 Days
• Field of Search: 340/10.4, 340/10.1, 340/572.7, 340/573.4, 340/572.3, 340/5.31, 340 58- 586, 455/411, 713/169, 380/258
• US Class Current: 340/10.4
• 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 19/073 Special arrangements for circuits, e.g. for protecting identification code in memory protection against unauthorised use of computer memory G06F12/14
• CPC Class Codes: G06K 19/07345 by activating or deactivating at least a part of the circuit on the record carrier, e.g. ON/OFF switches
• CPC Class Codes: G06K 19/07756 the connection being non-galvanic, e.g. capacitive
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies

Abstract

It is possible to prevent an unauthorized read-out from both active tags and passive tags. Antenna emission is turned on and off by using a switch, or attenuated by using a resistor. A part of the antenna may be chipped. With these configurations, it is possible to lower the emission level of the antenna thus preventing an unauthorized read-out of important information from a remote reader.

Claims

1. An RFID tag that stores data, comprising:

a first antenna for transmitting radio waves;

a transmission means for generating a transmission signal by modulating the data, and providing the transmission signal to the first antenna;

an emission control means for controlling an output power of the first antenna in order to transmit the transmission signal, the emission control means being connected to the first antenna and the transmission means;

a determination means for determining a value of the output power of the first antenna; and

an authentication means for authenticating an external device to which the radio waves from the first antenna are transmitted, wherein

the determination means determines the value of the output power to be set high when the external device is authenticated by the authentication means, and determines the value of the output power to be set low when the external device is not authenticated by the authentication means, and the emission control means controls the output power of the first antenna based on the value determined by the determination means; and

wherein

the RFID tag further comprises

a setting-receiving means for receiving settings of the values of the output power from the external device, and the determination means determines the value of the output power based on a setting command for the received settings of the values when the external device is authenticated by the authentication means; and

a second antenna for transmitting radio waves at an output power different from the output power of the first antenna, the second antenna being connected to the transmission means via the emission control means,

wherein the emission control means has a connection control means for disconnecting a connection between the first antenna and the transmission means.

2. The RFID tag according to claim 1, wherein the emission control means includes:

an attenuation means for attenuating the output power of the first antenna; and

an attenuation control means for controlling attenuation of the output power by the attenuation means.

3. The RFID tag according to claim 2, wherein the attenuation means includes a plurality of resistors, and

the attenuation control means connects the transmission means and the first antenna via at least one of the plurality of resistors.

4. The RFID tag according to claim 2, wherein the attenuation means includes a variable resistor connected between the transmission means and the first antenna, and

the attenuation control means adjusts a resistance value of the variable resistor.

5. The RFID tag according to claim 1, wherein the connection control means includes a switching means for switching the connection between the transmission means and the first antenna ON and OFF.

6. The RFID tag according to claim 5, further comprising a second antenna for transmitting radio waves at an output power different from the output power of the first antenna, the second antenna being connected to the transmission means via the emission control means.

7. The RFID tag according to claim 1, wherein the determination means determines the value of the output power to be set high when the external device is authenticated by the authentication means and confidentiality of the data to be transmitted is set high.

8. The RFID tag according to claim 1, wherein

the first antenna and the second antenna are electrically connected to the transmission means respectively.

9. The RFID tag according to claim 1 further, wherein

the first antenna is electrically connected to the transmission means, and the second antenna is magnetically connected to the first antenna.

10. The RFID tag according to claim 9, wherein

the first antenna and the second antenna are formed on a film having a tear-off line between the first and second antennas.

11. The RFID tag according to claim 1, wherein

the first antenna and the second antenna are formed on a film having a tear-off line between the first and second antennas.