JP4466426B2 - Non-contact reader / writer - Google Patents

Description

  The present invention relates to removal of a noise component of a fluorescent lamp included in a received signal when a transmission command that is particularly modulated by a non-contact reader / writer is transmitted.

  In recent years, wireless communication devices that are non-contact reader / writers have attracted attention as RFID (Radio Frequency Identification) systems.

  A general wireless communication device is equipped with an urban noise removal circuit to remove the fluorescent light noise, which is a kind of urban noise. (For example, refer to Patent Document 1).

  FIG. 10 shows an urban noise elimination circuit of the conventional wireless communication apparatus, wherein 101 is an antenna, 102 is a duplexer, 103 is a band pass filter, 104 is a low noise amplification circuit, 105 and 112 are mixers, 106, 113 is an intermediate frequency amplifier circuit, 107 and 114 are intermediate frequency band pass filters, 108 is a limiter amplifier circuit, 109 is a modulation circuit, 110 is an output, 111 and 118 are local oscillation circuits, 115 is a variable delay circuit, and 116 is a variable attenuator Circuit 117 is a hybrid.

The operation of the wireless communication apparatus configured as described above will be described. The wireless communication apparatus receives a signal with the antenna 101. At that time, the received signal includes noise. Since the noise signal has a different band from the received signal, the noise signal is selectively received by the signal path of the mixer 112, the noise reference signal is processed by the variable delay circuit 115 and the variable attenuator circuit 116, and the reference signal is converted by the hybrid 117. The noise component is removed from the received signal by performing reverse phase synthesis from the received signal.
JP-A-2-177617

  A reception signal received by a general wireless communication apparatus is a state in which a reception signal and a noise signal are mixed. In order to remove the noise signal, the conventional invention is equipped with an urban noise elimination circuit.

  The city noise elimination circuit has a means to select and receive only noise signals in a frequency band different from the received signal and obtain a noise reference signal. By processing the received signal based on the reference signal, the influence of city noise is obtained. I am trying not to receive it.

  Here, the communication method of the RFID system will be described. In the RFID system, it is necessary to always transmit a transmission radio wave for the two purposes of using a radio wave as a carrier for sending and receiving commands and supplying power to the tag. That is, load modulation using transmitted radio waves is used.

  In this load modulation method, when a command is transmitted from a reader / writer to a tag using a radio wave, the radio wave modulated by the command is transmitted. When a response signal is returned from the tag to the reader / writer, the modulation based on the presence or absence of reflection of the transmission radio wave is used.

In the load modulation method, the reception unit uses the received signal level in a state where there is no response from the tag as a reference, and uses the change amount of the signal level due to the load modulation of the tag and the changing time from the reference.

  The above is the transmission / reception system in the RFID system, but this RFID system has a significant problem.

  In the RFID system, the transmission command modulated as described above is transmitted, and transmission / reception is performed by load modulation from the tag. However, when a radio wave is transmitted from the reader / writer, if there is a fluorescent lamp near the antenna, it is output from the reader / writer. Radio waves enter the fluorescent lamp. In this case, the transmission radio wave of the reader / writer receives the modulation accompanying the light emission of the fluorescent lamp in the fluorescent lamp.

  The radio wave modulated by the fluorescent lamp is received by the reader / writer like the radio wave from the tag and becomes noise. This noise has the same frequency band as the received signal from the target tag, and in order to separate the received signal from the received signal, the conventional technique of selectively receiving the urban noise component as a reference signal and preventing it from being affected is Not applicable.

  An object of the present invention is to provide a non-contact reader / writer for the purpose of removing noise having the same frequency band as a received signal from a tag.

  The non-contact reader / writer of the present invention has a receiving antenna, an optical sensor, and a removing means for removing a signal obtained by multiplying the electromagnetic wave detected by the optical sensor by a predetermined coefficient from the electromagnetic wave signal received by the receiving antenna. The predetermined coefficient is determined using a feedback circuit.

  When a noise signal is generated from a fluorescent lamp by the modulation signal with the above configuration, the waveform pattern of the noise signal is detected from the optical sensor, and when removing it from the received signal, the signal level is determined by the feedback circuit, and the frequency band This is effective for noise signals of the same fluorescent lamp.

  The non-contact reader / writer of the present invention includes a receiving antenna, an optical sensor, a variable attenuator that multiplies a predetermined coefficient to the electromagnetic wave detected by the optical sensor, and an electromagnetic wave signal that is received by the receiving antenna as an output signal of the variable attenuator. And removing means for removing from.

  When a noise signal is generated from a fluorescent lamp by the modulation signal by the above configuration, the noise signal waveform pattern is detected by the optical sensor, and the noise signal level is adjusted and removed from the received signal by the variable attenuator. A reception signal without a signal is obtained and is effective for noise signals having the same frequency band.

  The non-contact reader / writer of the present invention includes a receiving antenna, an optical sensor, and a removing unit that removes a signal obtained by multiplying the electromagnetic wave detected by the optical sensor by a predetermined coefficient from the electromagnetic wave signal received by the receiving antenna, The predetermined coefficient is determined based on the signal received by the receiving antenna.

  When a noise signal is generated from the fluorescent lamp by the modulation signal with the above configuration, the waveform pattern of the noise signal is detected from the optical sensor, and the level of the noise signal is determined by the received signal, adjusted, and removed from the received signal. A received signal without a noise signal is obtained and effective for a noise signal having the same frequency band.

  In the non-contact reader / writer of the present invention, a shielded optical sensor is provided in a case that houses a receiving antenna.

  The above configuration reduces the influence of the modulation signal transmitted by the non-contact reader / writer on the optical sensor by shielding it, so that the received signal of the optical sensor approaches only the noise signal from the fluorescent lamp, and signal processing The accuracy of later received signals will be improved.

  The non-contact reader / writer of the present invention incorporates an optical sensor in the non-contact reader / writer and uses an optical fiber or a reflecting mirror for the input of the optical sensor.

  With the above configuration, the optical sensor itself is built in the non-contact reader / writer, and by making the input independent, the influence of the modulation signal transmitted by the non-contact reader / writer on the optical sensor is reduced, so that the optical sensor The received signal is brought close to only the noise signal from the fluorescent lamp, and the accuracy of the received signal after signal processing is improved.

  As described above, the present invention has an optical sensor that receives a noise signal from a fluorescent lamp and a removing unit that processes information from the optical sensor, so that radio waves emitted from the reader / writer are incident on the fluorescent lamp. It is useful for removing a signal modulated with light emission of a fluorescent lamp, that is, a noise signal.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.

(Embodiment 1)
In FIG. 1, 1 is a receiving antenna that receives radio waves, 2 is a demodulating unit that demodulates radio waves received by the receiving antenna 1, 3 is a noise removing unit that removes a signal from the optical sensor 8 from the received signal, and 4 is a demodulating unit. 2, a signal processing unit that processes the signal demodulated in 2, a signal generation unit that derives a modulation signal for transmitting a transmission command, 6 a modulation unit that modulates a carrier wave to transmit the transmission signal, and 7 a radio wave 8 is an optical sensor that detects a modulation associated with the emission of the fluorescent lamp by the radio wave transmitted from the transmitting antenna 7, that is, a noise signal that is a modulation signal in the same frequency band as the tag. The optical sensor 8 detects the waveform of the fluorescent lamp light and the reflected light thereof. The noise removing unit 3 removes this waveform as a noise component from the signal received by the receiving antenna. Reference numeral 9 denotes a coefficient feedback circuit that compares the signal from the optical sensor 8, the noise signal from the optical sensor 8, and the output signal from the noise removing unit 3 to determine the coefficient. This mechanism will be described later.

  The operation of the non-contact reader / writer configured as described above will be described.

  The signal generation unit 5 transmits a signal for communicating with the tag, the modulation unit 7 performs modulation for transmitting a command, and the transmission antenna 8 transmits the signal modulated by the modulation unit 7.

  The receiving antenna 1 receives the signal responded by the tag with the signal from the transmitting antenna 8, and the demodulator 2 demodulates the received signal.

  The optical sensor 8 detects the modulation associated with the emission of the fluorescent lamp by the radio wave transmitted from the transmitting antenna 7, that is, the noise signal in the same frequency band as the tag.

The noise removing unit 3 removes the received light signal received by the receiving antenna 1 from the signal after demodulated by the demodulating unit 2 and the fluorescent lamp noise signal of the optical sensor 8. The noise removing unit 3 can be configured with a known filter.
The coefficient feedback circuit 9 compares the output signal of the noise removing unit 3 with the fluorescent lamp noise signal from the optical sensor, and automatically determines the optimum level of the fluorescent lamp noise signal to be removed.
Specifically, first, the noise signal from the optical sensor 8 and the output signal of the noise removal unit 3 are compared by a waveform comparison unit (not shown) included in the coefficient feedback circuit. As a result of the comparison, if the noise signal is completely removed, the output signal of the noise removing unit 3 has a clean waveform. If the noise remains, for example, the output signal of the noise removing unit 3 has a whiskers. Occur. If this whiskers are present, the noise has not been removed accurately, so the coefficient of the adaptive filter included in the coefficient feedback circuit is changed, the amplitude and wavelength of the noise signal are changed, and the changed noise is changed. The signal is removed again by the signal removal unit 3. The result is fed back to the coefficient feed back circuit 9 again, and if the noise component remains, the same operation is performed again. By repeating this, a signal waveform from which noise has been removed is obtained.
For example, the noise amplitude level of the adaptive filter used in the coefficient feedback circuit 9 is set to be 1 / n of the signal amplitude level, and the amplitude level of the incoming noise is adjusted. This adjusted noise is removed by the noise removing unit 3, the resulting signal waveform is compared with the noise waveform, and the operation of adjusting the noise amplitude level again is repeated.

  As a result, an optimum coefficient is derived by the coefficient feedback circuit 9, and the noise signal from the optical sensor 8 adjusted by the coefficient feedback circuit 9 is removed from the received signal, so that the fluorescent light having the same frequency band as the received signal can be obtained. Noise signal can be removed.

  Although the optical sensor is made independent in the first embodiment, it may be a receiving antenna 10 with a built-in optical sensor that is shielded and arranged in the receiving antenna 1 as shown in FIG.

  In the first embodiment, the optical sensor is made independent. However, as shown in FIG. 3, the optical sensor is arranged inside the non-contact reader / writer so that the input to the optical sensor is not easily affected by the radio wave of the optical fiber or the reflecting mirror. You may receive the noise signal from a fluorescent lamp using the optical system 11. FIG.

(Embodiment 2)
Next, an embodiment in which the coefficient feedback circuit 9 is changed to a variable attenuator unit and a feedback circuit using the variable attenuator unit 12 will be described.

  In FIG. 4, 1 is a receiving antenna that receives radio waves, 2 is a demodulating unit that demodulates radio waves received by the receiving antenna 1, 3 is a noise removing unit that removes a signal from the optical sensor 9 from the received signal, and 4 is a demodulating unit. 2, a signal processing unit that processes the signal demodulated in 2, a signal generation unit that derives a modulation signal for transmitting a transmission command, 6 a modulation unit that modulates a carrier wave to transmit the transmission signal, and 7 a radio wave 8 is an optical sensor for detecting a noise signal that is a modulation signal in the same frequency band as that of the tag, and 12 is an optical sensor. The variable attenuator for changing the level of the noise signal of the fluorescent lamp received in step 8 is compared with the output of the received signal after removing the noise signal after the noise removing unit 3 and the noise signal from the fluorescent lamp. In contrast, the variable attenuator unit automatically determines an optimum coefficient value using a feedback circuit.

  The difference from the first embodiment is not the coefficient feedback circuit, but the point that the coefficient for removing the noise signal in the same frequency band as the received signal is automatically determined by the feedback circuit using a variable attenuator.

  The operation of the non-contact reader / writer configured as described above will be described.

  The signal generation unit 5 transmits a signal for communicating with the tag, the modulation unit 7 performs modulation for transmitting a command, and the transmission antenna 8 transmits the signal modulated by the modulation unit 7.

The receiving antenna 1 receives the signal responded by the tag with the signal from the transmitting antenna 8, and the demodulator 2 demodulates the received signal.

  The optical sensor 8 detects a modulation associated with the fluorescent lamp emitting light by the radio wave transmitted from the transmitting antenna 7, that is, a noise signal that is a modulation signal in the same frequency band as the tag.

  The noise removing unit 3 removes the received light signal received by the receiving antenna 1 from the signal after demodulated by the demodulating unit 2 and the fluorescent lamp noise signal of the optical sensor 8.

  The variable attenuator unit 12 is composed of resistance, reactance, and capacitance elements. Here, the output of the received signal after removing the noise signal after the noise removing unit 3 is compared with the noise signal from the fluorescent lamp, and the feedback circuit Thus, the optimum value of the variable attenuator 12 is automatically determined and the level of the noise signal to be removed is optimally adjusted. The variable attenuator unit 12 has an attached circuit that automatically changes its resistance value, and changes the resistance value based on the correlation between the waveform of the output signal of the noise removing unit 3 and the noise signal. When the resistance value of the variable attenuator 12 changes, the signal level changes. In the same manner as in the first embodiment, the signal removal unit 3 repeats the operation of comparing the signal resulting from the removal of the noise component with the noise signal again to remove the noise.

  As a result, the optimum signal level of the noise signal is adjusted by the variable attenuator unit 12 and the signal waveform from the optical sensor 8 is removed from the received signal, so that the noise signal from the fluorescent lamp having the same frequency band as the received signal can be obtained. Removal is possible.

  Although the optical sensor is made independent in the second embodiment, it may be a receiving antenna 10 with a built-in optical sensor that is shielded and arranged in the receiving antenna 1 as shown in FIG.

  Although the optical sensor is made independent in the second embodiment, it is arranged inside the non-contact reader / writer as shown in FIG. 6 and is guided to be hardly influenced by the radio wave of the optical fiber or the reflector as an input to the optical sensor. You may receive the noise signal from a fluorescent lamp using the optical system 11. FIG.

(Embodiment 3)
Next, an embodiment in which the variable attenuator unit 12 is changed to a manual variable attenuator 13 will be described.

  In FIG. 7, 1 is a receiving antenna that receives radio waves, 2 is a demodulating unit that demodulates radio waves received by the receiving antenna 1, 3 is a noise removing unit that removes a signal from the optical sensor 9 from the received signal, and 4 is a demodulating unit. 2, a signal processing unit that processes the signal demodulated in 2, a signal generation unit that derives a modulation signal for transmitting a transmission command, 6 a modulation unit that modulates a carrier wave to transmit the transmission signal, and 7 a radio wave 8 is an optical sensor for detecting a noise signal that is a modulation signal when the fluorescent lamp emits light by the radio wave transmitted from the transmitting antenna 7, that is, a modulation signal in the same frequency band as the tag, and 13 is an optical sensor. 8 is a variable attenuator that varies the level of the noise signal of the fluorescent lamp received in step 8.

  The difference from the first embodiment is not a coefficient feedback circuit but a variable attenuator 13 that determines a single coefficient when removing a noise signal in the same frequency band as the received signal.

  The operation of the non-contact reader / writer configured as described above will be described.

  The signal generation unit 5 transmits a signal for communicating with the tag, the modulation unit 7 performs modulation for transmitting a command, and the transmission antenna 8 transmits the signal modulated by the modulation unit 7.

  The receiving antenna 1 receives the signal responded by the tag with the signal from the transmitting antenna 8, and the demodulator 2 demodulates the received signal.

  The optical sensor 8 detects a modulation associated with the fluorescent lamp emitting light by the radio wave transmitted from the transmitting antenna 7, that is, a noise signal that is a modulation signal in the same frequency band as the tag.

  The noise removing unit 3 removes the fluorescent lamp noise signal of the optical sensor 8 from the signal obtained by demodulating the received signal received by the receiving antenna 1 by the demodulating unit 2.

  The variable attenuator 13 optimally adjusts the level of the noise signal removed from the received signal with respect to the signal level of the fluorescent lamp noise signal from the optical sensor 8.

  As a result, the optimum signal level of the noise signal is adjusted by the variable attenuator 13, and the signal waveform and signal level from the optical sensor 8 determined in a single manner are removed from the received signal, so that the same frequency band as the received signal is obtained. The noise signal from a certain fluorescent lamp can be removed.

  Although the optical sensor is made independent in the third embodiment, it may be a receiving antenna 10 with a built-in optical sensor that is shielded and arranged in the receiving antenna 1 as shown in FIG.

  Although the optical sensor is made independent in the third embodiment, the optical sensor is arranged inside the non-contact reader / writer as shown in FIG. 9 and is not easily affected by the radio wave of the optical fiber or the reflector as an input to the optical sensor. You may receive the noise signal from a fluorescent lamp using the optical system 11. FIG.

  The non-contact reader / writer of the present invention is useful for removing noise from a fluorescent lamp and is industrially useful.

Configuration diagram of Embodiment 1 of the wireless transmission / reception apparatus of the present invention Another configuration diagram of the wireless transceiver according to the first embodiment of the present invention (part 1) Another configuration diagram of the wireless transceiver according to the first embodiment of the present invention (No. 2) Configuration diagram of Embodiment 2 of the wireless transmission / reception apparatus of the present invention Another configuration diagram of the wireless transceiver according to the second embodiment of the present invention (part 1) Another configuration diagram of the wireless transceiver according to the second embodiment of the present invention (part 2) Configuration diagram of Embodiment 3 of the wireless transceiver of the present invention Another block diagram in Embodiment 3 of the radio | wireless transmitter / receiver of this invention (the 1) Another configuration diagram according to the third embodiment of the wireless transceiver of the present invention (No. 2) Configuration diagram of conventional technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reception antenna 2 ... Demodulation part 3 ... Noise removal part 4 ... Signal processing part 5 ... Signal generation part 6 ... Modulation part 7 ... Transmission antenna 8 ... -Optical sensor 9 ... Coefficient feedback circuit 10 ... Receiving antenna with built-in optical sensor 11 ... Light guide system 12 ... Variable attenuator unit 13 ... Variable attenuator

Claims (5)

A receiving antenna; an optical sensor; and a removing means for removing a signal obtained by multiplying the electromagnetic wave detected by the optical sensor by a predetermined coefficient from the electromagnetic wave signal received by the receiving antenna, and determining the coefficient using a feedback circuit. Non-contact reader / writer. Non-contact reader / writer having a receiving antenna, an optical sensor, a variable attenuator for multiplying an electromagnetic wave detected by the optical sensor by a predetermined coefficient, and a removing means for removing an output signal of the variable attenuator from the electromagnetic wave signal received by the receiving antenna . A receiving antenna, an optical sensor, and a removing means for removing a signal obtained by multiplying the electromagnetic wave detected by the optical sensor by a predetermined coefficient from the electromagnetic wave signal received by the receiving antenna, and the signal received by the receiving antenna Non-contact reader / writer that decides based on. The non-contact reader / writer according to claim 1, wherein a shielded optical sensor is provided in a case housing the receiving antenna. 4. The non-contact reader / writer according to claim 1, wherein an optical sensor is built in the non-contact reader / writer, and an optical fiber or a reflecting mirror is used as an input of the optical sensor.

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