Wireless communication tag and wireless communication system

1. A wireless communication tag previously set with predetermined identification information, the wireless communication tag comprising:

(i) a first antenna for wirelessly communicating various types of data between a reader/writer and an IC device;

(ii) a controller for controlling the data communicated through the first antenna;

(iii) a second antenna for receiving an electromotive radio wave for generating electric power from an electromotive radio wave; and

(iv) a charging unit for generating electric power from the electromotive radio wave received by the second antenna as well as for storing the generated electric power,

wherein:

the electric power stored in the charging unit is used, thereby allowing either one of the first and second antennas to provide, to the reader/writer, data relating to the identification information,

the wireless communication tag further comprises a diode disposed between the IC device and the charging unit, and

the diode exercises ON/OFF control of direct current voltage that is applied from the charging unit to the IC device, in order to activate the IC device by means of electric power generated and stored by the charging unit, when a radio wave that is received by the first antenna is weak.

2. The wireless communication tag according to claim 1 , wherein:

the second antenna wirelessly transmits the identification data to the reader/writer when the first antenna wirelessly receives the identification data from the reader/writer.

3. The wireless communication tag according to claim 1 , wherein:

a radio wave frequency at the time of communication between the first antenna and the reader/writer and a frequency of the electromotive radio wave received from the second antenna are set different from each other.

4. The wireless communication tag according to claim 1 , wherein:

a memory unit for previously storing the identification information as well as for storing the data controlled by the controller.

5. The wireless communication tag according to claim 1 , wherein:

the charging unit includes a rectifying circuit and a secondary battery unit; and

the secondary battery unit stores an electromotive force rectified by the rectifying circuit upon receipt of the electromotive radio wave from the second antenna.

6. The wireless communication tag according to claim 5 , wherein:

the rectifying circuit is formed as a bridge circuit.

7. The wireless communication tag according to claim 1 , further comprising a resonant circuit.

8. The wireless communication tag according to claim 1 , wherein:

the second antenna is configured of a resonant circuit.

9. A wireless communication tag, comprising:

(i) an IC device for storing predetermined identification information;

(ii) a first antenna for receiving, from an external reader/writer, a first radio wave including a reading-command signal and for transmitting, to the external reader/writer, the predetermined identification information stored in the IC device and read out by the reading-command signal;

(iii) a second antenna for receiving a second electromotive radio wave from an external predetermined device; and

(iv) a charging unit for storing electric power generated from the second radio wave received by the second antenna,

wherein:

in the case where the first radio wave received by the first antenna is strong, the wireless communication tag activates the IC device with a current caused by the received strong first radio wave and reads out the predetermined identification information stored in the IC device in response to the command signal included in the first radio wave;

in the case where the first radio wave received from the first antenna is weak, the wireless communication tag activates the IC device with a resultant current of a current caused by the received weak first radio wave and a current from the charging unit previously storing the electric power and reads out the predetermined identification information stored in the IC device in response to the command signal included in the first radio wave;

the wireless communication tag transmits, through the first antenna to the external reader/writer, the predetermined identification information read out of the IC device with use of a radio wave obtained from the resultant current including the current from the charging unit;

the wireless communication tag further comprises a diode that is disposed between the IC device and the charging unit; and

the diode exercises ON/OFF control of a direct current voltage that is applied from the charging unit to the IC device in order to activate the IC device by means of electric power generated and stored by the charging unit when a radio wave that is received by the first antenna is weak.

10. A wireless communication system, comprising:

(a) a reader/writer for transmitting a first radio wave including a reading-command signal;

(b) a radio wave transmitting device for transmitting a second, electromotive radio wave; and

(c) a wireless communication tag including:

(i) an IC device for storing predetermined identification information;

(ii) a first antenna for receiving a first radio wave from the reader/writer and for transmitting to the reader/writer the predetermined identification information stored in the IC device read out in response to the command signal included in the first radio wave;

(iii) a second antenna for receiving a second radio wave from the radio wave transmitting device; and

(iv) a charging unit for storing electric power generated from the second radio wave received from the second antenna,

wherein:

in the case where the first radio wave received from the first antenna is strong, the wireless communication tag activates the IC device with a current caused by the received strong first radio wave and reads out the predetermined identification information stored in the IC device in response to the command signal included in the first radio wave;

in the case where the first radio wave received from the first antenna is weak, the wireless communication tag activates the IC device with a resultant current of a current caused by the received weak first radio wave and a current from the charging unit previously storing the electric power and reads out the predetermined identification information stored in the IC device in response to the command signal included in the first radio wave;

the wireless communication tag transmits, through the first antenna to the reader/writer, the predetermined identification information read out of the IC device with use of a radio wave obtained from the resultant current including the current from the charging unit;

the wireless communication tag further comprises a diode that is disposed between the IC device and the charging unit; and

the diode exercises ON/OFF control of a direct current voltage that is applied from the charging unit to the IC device in order to activate the IC device by means of electric power generated and stored by the charging unit when a radio wave that is received from the first antenna is weak.

11. A wireless communication tag, comprising:

(i) an IC device for storing predetermined identification information;

(ii) an antenna for receiving a first radio wave which is inclusive of a command signal from a reader/writer, in order to transmit the predetermined identification information stored in the IC device to the reader/writer, and for receiving a second, electromotive radio wave from an external predetermined device;

(iii) a charging unit for generating electric power from the second radio wave received from the antenna and for storing the generated electric power; and

(iv) a current control unit which is disposed between the IC device and the charging unit for exercising ON/OFF control of a current to be supplied from the charging unit to the IC device in accordance with an intensity of the first radio wave received by the antenna,

wherein the current control unit exercises ON/OFF control of a current 1) to read out the predetermined identification information stored in the IC device with use of an electromotive force obtained by the received first radio wave when the first radio wave received from the antenna is strong; and 2) to read out the predetermined identification information stored in the IC device with use of electric power stored in the charging unit when the first radio wave received from the antenna is weak, the electric power stored in the charging unit having been generated by reception of the second radio wave.