Reader/writer and RFID system
First Claim
Patent Images
1. A reader/writer comprising:
- a transmitter operable to transmit an interrogation signal to an RF tag; and
a receiver operable to receive a response signal from an RF tag;
wherein the transmitter is operable to transmit an interrogation signal based on a synchronization signal received from another reader/writer.
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Abstract
A system establishes synchronicity of transmission and receiving for each reader/writer of an RF tag independently without obtaining synchronization of the reader/writers by means of an unspecified number of control terminals is desired as a reader/writer system. A reader/writer comprises a transmitter operable to transmit an interrogation signal to an RF tag, and a receiver operable to receive a response signal from an RF tag, wherein the transmitter is operable to transmit an interrogation signal based on a synchronization signal received from another reader/writer.
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Citations
26 Claims
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1. A reader/writer comprising:
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a transmitter operable to transmit an interrogation signal to an RF tag; and
a receiver operable to receive a response signal from an RF tag;
wherein the transmitter is operable to transmit an interrogation signal based on a synchronization signal received from another reader/writer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A reader/writer for performing wireless communication with an RF tag, comprising:
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a receiver operable to receive wireless signals;
a device operable to halt transmission of wireless signals and to confirm whether there is a synchronization signal from an other reader/writer; and
a transmitter operable to transmit a wireless signal synchronized to timing of the other reader/writer obtained based on the synchronization signal when the transmission of the synchronization signal is confirmed, and to transmit a wireless signal by its own timing when it is confirmed that the synchronization signal has not been transmitted. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An RFID system having a plurality of reader/writers, the RFID system comprising:
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a first reader/writer operable to broadcast a synchronization signal on a frequency other than a frequency for transmitting and receiving wireless signals; and
a second reader/writer operable to receive the synchronization signal and to transmit wireless signals in a transmission timing based on the synchronization signal.
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18. A reader/writer for exchanging wireless signals with an RF tag, the reader/writer comprising:
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a device operable to perform receiving and transmission of wireless signals by opening an interval in which a synchronization signal can be transmitted; and
a measuring device operable to measure signal intensity of the synchronization signals received by the device, and, if the synchronization signals that can be transmitted during the interval are full, to transmit synchronization signals in timing of a synchronization signal having a weakest signal intensity among those measured by the measuring device. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A reader/writer for performing wireless communication with an RF tag, the reader/writer comprising:
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a receiver operable to receive wireless signals;
a device operable to confirm whether a synchronization signal from another reader/writer exists while transmitting an unmodulated wave; and
a transmitter operable to transmit a wireless signal synchronized with transmission timing of another reader/writer obtained based on the synchronization signal when the synchronization signal is confirmed, and to transmit a wireless signal in its own transmission timing when absence of such synchronization signal is confirmed.
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26. A reader/writer for performing wireless communication with an RF tag, the reader/writer comprising:
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a measuring device operable to measure a reception level of synchronization signals received; and
a detecting device operable to detects synchronization signals in which the measured reception level is at or above a threshold value, to calculate an average transmission timing of that synchronization signal, and to correct the transmission timing of synchronization signals based on the average of the transmission timings obtained by the calculation.
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Specification