JP2000020651A - Reader/writer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid interference of a carrier wave between a reader and a writer, even if, for example, plural readers/writers are provided adjacent in a reader/ writer which generated the carrier wave and radio communicates with a mobile information communication object, such as an ID tag via the carrier wave. SOLUTION: A reader/writer R1 is equipped with a synthesizer part 1 having a carrier wave generating means that can change the frequency of a generated carrier wave, has a modulator 2 for modulating the carrier wave generated from the synthesizer part 1, and radio communicates information with an ID tag T1 by radio transmitting the modulates carrier wave via a transmission amplifier 3 or a circulator 4 from an antenna 5. The synthesizer part 1 is constituted of, for example, an oscillator 21 which makes the frequency variable and generates the carrier wave, an adjustment means 23 which changes an oscillation frequency of the oscillator 21 according to the input from the outside by controlling the oscillator 21 via a loop filter 24, and a crystal oscillator 22 for supplying the adjustment means 23 with a signal of a specified frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reader / writer for generating a carrier wave and wirelessly communicating information with a mobile information communication body such as an ID tag via the carrier wave, and in particular, a plurality of reader / writers are installed adjacent to each other. Even if
The present invention relates to a reader / writer that avoids carrier wave interference between adjacent reader / writers.

[0002]

2. Description of the Related Art In a non-contact ID tag system, for example, a reader / writer (interrogator) is fixedly installed, while an ID tag (responder), which is a simple communication device, is attached to a mobile object such as an object or a person. Power is transmitted and information is communicated between the reader / writer and the ID tag via a carrier wave wirelessly transmitted from the reader / writer.

FIG. 2 shows an example of a circuit configuration of a reader / writer R2 and an ID tag T2 provided in such a system. Note that an information processing device (not shown) is connected to the reader / writer R2 via an interface, and information (question data) to be transmitted to the ID tag T2 and clock information are transmitted through the interface to the information processing device. Via the interface, the function of receiving information (response data) received by the reader / writer R2 from the ID tag T2 via the interface, and the function of receiving from the reader / writer R2 in this way. A function of performing processing of the information or the like is provided.

[0004] The reader / writer R2 shown in FIG.
A reference frequency oscillator 41 for generating a carrier, a modulator 42 for performing a modulation process, a transmission amplifier (amplifier) 43 for amplifying the carrier, a circulator 44 for executing a transmission / reception process with one antenna 45, and transmitting and receiving a wireless carrier. An antenna 45, a distributor 46 for distributing the received carrier, a phase shifter 47 for shifting the phase of the received carrier,
The first mixer 48, the first filter 49, and the first reception amplifier (amplifier) 50 that constitute the reception system of the first embodiment, and the second mixer 51, the second filter 52, and the second filter 52 that constitute the second reception system. 2, a receiving amplifier (amplifier) 53, a combining amplifier (amplifier) 54 for combining demodulated waves obtained by the first receiving system and the second receiving system, and a level converter 55 for performing analog-digital conversion processing. Is provided.

[0005] The reference frequency oscillator 41 has a function of generating a carrier having a constant frequency and outputting the generated carrier to the modulator 42. The modulator 42 has a function of, when outputting the carrier wave input from the reference frequency oscillator 41 to the transmission amplifier 43, for example, when question data is input from an external information processing device, amplitude modulating the carrier wave with the query data. are doing.

The transmission amplifier 43 has a function of amplifying the carrier inputted from the modulator 42 and outputting the amplified carrier to the circulator 44, the first mixer 48 and the second mixer 51. The circulator 44 is the transmitting amplifier 4
The carrier (transmitted carrier) input from 3 is transmitted to antenna 45
And a function of outputting the carrier (received carrier) input from the antenna 45 to the distributor 46. With this function, one antenna 45 is shared to perform transmission processing and reception processing. That has been realized.

The antenna 45 transmits the carrier wave input from the circulator 44 by radio waves or the like,
It has a function of receiving response data wirelessly transmitted from the tag T2 using a carrier wave and outputting the received carrier wave to the circulator 44. The distributor 46 is a circulator 4
4 has a function of distributing the carrier wave input from 4 to two receiving systems. Specifically, one of the two divided carrier waves is output to the phase shifter 47, and the other is transmitted to the second mixer 51. Output.

The phase shifter 47 has a function of shifting (shifting) the phase of the carrier input from the distributor 46 and outputting the phase-shifted carrier to the first mixer 48. Thus, for example, the phase of the carrier input to the first receiving system and the phase of the carrier input to the second receiving system are shifted by 90 °. The first mixer 48 mixes the carrier (reception carrier) input from the phase shifter 47 and the carrier (transmission carrier) input from the transmission amplifier 43, and uses the mixed carrier as a first demodulated wave as a first demodulated wave. It has a function of outputting to the filter 49.

The first filter 49 removes unnecessary components from the first demodulated wave input from the first mixer 48, and receives the first demodulated wave from which the unnecessary components have been removed for the first reception. It has a function of outputting to the amplifier 50. The first receiving amplifier 50 amplifies the first demodulated wave input from the first filter 49 and combines the amplified first demodulated wave with the synthesized amplifier 5.
4, and amplifies the first demodulated wave to a level at which it can be easily processed, for example.

The second mixer 51 has the same function as the first mixer 48 described above, that is, the distributor 46
Carrier (reception carrier) input from the transmission amplifier 43
And a carrier (transmission carrier) input from the second filter 52, and the mixed carrier is used as a second demodulated wave in the second filter 52.
It has the function of outputting to The second filter 52 has a function similar to that of the first filter 49 described above.
That is, a function of removing unnecessary components from the second demodulated wave input from the second mixer 51 and outputting the second demodulated wave after removing the unnecessary components to the second receiving amplifier 53 is provided. Have.

The second receiving amplifier 53 has a function similar to that of the first receiving amplifier 50 described above. That is, the second receiving amplifier 53 amplifies the second demodulated wave input from the second filter 52 and amplifies the second demodulated wave. The second demodulated wave is output to the synthesis amplifier 54, and the amplification function amplifies the second demodulated wave to a level that can be easily processed, for example.

The combining amplifier 54 combines the first demodulated wave input from the first receiving amplifier 50 and the second demodulated wave input from the second receiving amplifier 53, and obtains the resulting combined signal. It has a function of outputting a wave to the level converter 55 with an analog level. When the response data is received from the ID tag T2 by the antenna 45, the first demodulated wave and the second demodulated wave input to the composite amplifier 54 and the composite wave output from the composite amplifier 54 include: The received response data is included.

The level converter 55 has a function of digitizing a synthesized wave input from the synthesis amplifier 54. With this function, for example, the synthesized wave input from the synthesis amplifier 54 is converted into response data composed of a digital signal. Then, the converted response data is output to, for example, an external information processing device.

With the above configuration, the reader / writer R
In 2, for example, wirelessly transmitting power to the ID tag T2 via the generated carrier, or modulating the carrier in accordance with an input from the information processing device and wirelessly transmitting interrogation data or clock information to the ID tag T2. And the ID tag T2
Demodulated information (response data) wirelessly received from the PC, and transmits the demodulated response data to the information processing apparatus via an interface.

The ID tag T2 shown in FIG. 2 includes an antenna 61 for transmitting / receiving a radio carrier, a modulator / demodulator 62 for performing a modulation process and a demodulation process, and a ROM or the like which is a nonvolatile memory, for example. A memory 63 and a control unit 64 that performs various processes and controls such as reading and writing of information from and to the memory 63 are provided. In addition,
A power source such as a battery is not provided inside the ID tag T2 shown in FIG.
Various operations are performed using the power wirelessly received from the power supply 2. The antenna 61 has a function of receiving a carrier wave wirelessly transmitted from the reader / writer R2 and outputting the received carrier wave to the modem 62, and wirelessly transmitting information (response data) input from the modem 62 by the carrier wave. are doing.

The modulator / demodulator 62 extracts power from the carrier wave input from the antenna 61, and extracts the power from the carrier 63 and the control unit 64.
And demodulation processing by extracting query data and clock information from the carrier wave input from the antenna 61, and outputting the demodulated query data and clock information to the control unit 64. It has a function of amplitude-modulating a carrier according to the information (response data) input from 64 and outputting the modulated carrier to the antenna 61.
In the modulator / demodulator 62, for example, a carrier wave wirelessly received from the reader / writer R2 by the antenna 61 is returned as a reflected wave from the antenna 61, so that the reflected wave is modulated and response data is wirelessly transmitted to the reader / writer R2. Is done.

The memory 63 has a function of storing information. For example, the memory 63 stores information (ID data) of an identifier (ID) and the like. As described above, the control unit 64
It has a function of performing various processes and controls in the D tag T2. For example, by using information of a clock input from the modem 62, it is stored in the memory 63 in accordance with the contents of the question data input from the modem 62. It has a function of reading the written information, writing the information in the memory 63, and outputting information (response data) to be transmitted to the reader / writer R2 to the modem 62.

With the above configuration, the ID tag T2 demodulates the information (question data) wirelessly received from the reader / writer R2 by using, for example, the power wirelessly received from the reader / writer R2 via a carrier wave as the operating power. And information (response data) is wirelessly transmitted to the reader / writer R2 in accordance with the content of the demodulated question data.

Next, for example, the ID stored in the ID tag T2 is
As an example, a system in which the reader / writer R2 reads the D data in a non-contact manner to identify the ID tag T2,
The processing performed between the reader / writer R2 and the ID tag T2 described above will be described more specifically.

For example, in the installed reader / writer R2, a carrier is modulated with interrogation data by the modulator 42, and the modulated carrier is wirelessly transmitted from the antenna 45 via the transmission amplifier 43 or the circulator 44, for example. When an object or the like with the ID tag T2 approaches the reader / writer R2 and enters a communicable area of the reader / writer R2 (that is, a service area in which the ID tag T2 can operate), communication of information between the two starts. Is done.

That is, in the ID tag T2 which has entered the service area of the reader / writer R2, when the carrier transmitted by radio from the reader / writer R2 is received by the antenna 61, the modem 62 uses the received carrier to transmit interrogation data. And the information of the clock and the clock is demodulated, and the demodulated information is analyzed by the control unit 64. In the ID tag T2, the control unit 64 reads and writes the memory 63 according to the content of the analyzed question data. For example, the ID data stored and held in the memory 63 is used as response data via the modem 61 via the modem 62. Is returned to the reader / writer R2.

On the other hand, in the reader / writer R2, the ID tag T
2 is received by the antenna 45 as a reflected wave, and the received carrier is input to the first receiving system and the second receiving system via the circulator 44 and the distributor 46 for receiving processing. Will be

Here, as described above, the phase of the carrier inputted to the first receiving system is shifted by 90 ° by the phase shifter 47, whereby, for example, the response data is demodulated from the received carrier in one receiving system. Even if this is difficult, it is guaranteed that the response data is normally demodulated by the other receiving system. That is, in the configuration shown in FIG. 2, since the ID tag T2 returns a carrier wave wirelessly transmitted from the reader / writer R2 as a reflected wave to perform information communication between the two, for example, one reception system With only the above, depending on the positional relationship between the reader / writer R2 and the ID tag T2, the phase difference between the transmission carrier and the reception carrier may become 180 °, making it impossible to demodulate the response data. By providing two receiving systems, such a problem is solved.

In the receiving process in the reader / writer R2,
As described above, the transmission carrier and the reception carrier are
The demodulation of the response data is performed by mixing the data by 8 and 51. That is, as described above, the ID tag T2
In the case, the carrier received from the reader / writer R2 is modulated by, for example, only the response data, and the modulated carrier is returned to the reader / writer R2 as a reflected wave.
The reader / writer R2 can obtain response data that is a difference between the transmission carrier and the reception carrier through the above-described mixing process.

In the reader / writer R2, unnecessary waves are removed or amplified by the filters 49 and 52 and the receiving amplifiers 50 and 53, so that the demodulated waves obtained in the first receiving system and the second receiving system are obtained. By synthesizing by the synthesizing amplifier 54 and digitizing the resultant wave by the level converter 55, the response data returned from the ID tag T2 is reproduced and output in the form of a digital signal. Thus, in the reader / writer R2, for example, the ID tag T2
Can be received and demodulated as response data, and in this system, the ID tag T2 is identified using the ID data thus obtained.

[0026]

However, in such a reader / writer as described above, for example, when it is necessary to configure a system capable of identifying many ID tags at a time, a plurality of reader / writers are placed adjacent to each other. It may be necessary to install the reader / writer, but if a plurality of reader / writers are installed adjacent to each other in this way, interference of carrier waves occurs between adjacent reader / writers, and the reader / writer and the ID
There was a problem that information communication with a tag was not performed normally.

For example, the reader / writer R2 shown in FIG.
In the case where a plurality of reader / writers are provided, the frequency of the carrier wave generated by the reference frequency oscillator 41 is fixed to the same frequency for all the reader / writers.
Although information communication can be performed without any problem with the D tag, when a plurality of reader / writers are installed adjacent to each other, the information communication between each reader / writer and the ID tag can be performed by another adjacent reader / writer. A carrier wave wirelessly transmitted from the reader / writer has sometimes been disturbed.

Here, as a specific example of the problem caused by the interference of the carrier wave as described above, for example, the ID tag is transmitted from the reader / writer due to interference of the carrier waves wirelessly transmitted from a plurality of adjacent reader / writers. There is a problem that the received carrier wave cannot be normally received. Also, for example, in the system as shown in the above conventional example, a carrier wave wirelessly transmitted from an ID tag to one reader / writer as a reflected wave and a carrier wave wirelessly transmitted from another adjacent reader / writer may interfere with each other. Therefore, there is a problem that the one reader / writer cannot normally receive the response data transmitted from the ID tag.

Due to such a defect, for example, when a plurality of reader / writers are installed adjacent to each other to identify a plurality of ID tags at a time, the reader / writer and the
The problem that information communication with the tag becomes almost impossible, and the communication distance and area where information communication can be performed between the reader / writer and the ID tag become extremely small. Had occurred.

The present invention has been made to solve such a conventional problem. A reader / writer which generates a carrier wave and wirelessly communicates information with a mobile information communication body such as an ID tag via the carrier wave is provided. For example, an object of the present invention is to provide a reader / writer capable of avoiding carrier wave interference between adjacent reader / writers even when a plurality of reader / writers are installed adjacent to each other.

[0031]

In order to achieve the above-mentioned object, a reader / writer according to the present invention has means for generating a carrier wave, and wirelessly communicates information with a mobile information communication body via the carrier wave. The carrier generation means is configured as follows. That is, the carrier generation means is provided with an oscillator for generating a carrier wave by changing the frequency, and an adjusting means for changing the oscillation frequency of the oscillator in accordance with an external input.

Therefore, even when a plurality of reader / writers are installed adjacent to each other, for example, by changing the oscillation frequency of the oscillator by the adjusting means of each reader / writer, radio transmission from the adjacent reader / writers is performed. Since the frequencies of the carrier waves can be different from each other, it is possible to avoid carrier interference between adjacent reader / writers. Thus, for example, even when a system in which a plurality of mobile information communication bodies can be identified at a time by installing a plurality of reader / writers adjacent to each other is configured, the communication between the reader / writer and the mobile information communication body can be performed. Normal information communication can be ensured between the reader and writer, and the communication distance at which information communication can be performed between the reader / writer and the mobile information communication body is reduced due to carrier wave interference. Etc. can be prevented.

The mobile information communication body referred to in the present invention includes:
Not only the above-mentioned ID tag, but also, for example, an IC card, a name plate attached to a person, an identification plate attached to livestock, a delivery destination plate attached to courier luggage, or a container. Various mobile information communication bodies such as delivery destination plates are also included.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a circuit configuration of a reader / writer R1 according to the present invention, and an IC having a function of wirelessly transmitting power and communicating information with the reader / writer R1.
5 shows a circuit configuration example of the D tag T1. Here, the antenna 31 and the modulator / demodulator 3 provided in the ID tag T1 of this example are used.
2 and the configuration and operation of the control unit 34 are substantially the same as those of the ID tag T2 shown in FIG. 2, for example, and in this example, the processing units 31 to 31 provided in the ID tag T1 are provided.
Description of the configuration and operation of 34 is omitted.

The reader / writer R1 of the present embodiment shown in FIG.
FIG. 2 shows a synthesizer unit 1 for generating a carrier wave.
, A transmission amplifier (amplifier) 3, a circulator 4, an antenna 5, a distributor 6, a phase shifter 7, a first reception system, and the like. , A first mixer 8, a first filter 9, and a first receiving amplifier (amplifier) 10, or a second mixer 11, a second filter 12, and a second receiving unit that form a second receiving system. An amplifier (amplifier) 13, a synthesis amplifier (amplifier) 14, and a level converter 15 are provided.

Here, the main parts of the present invention relate to the configuration and operation of the synthesizer unit 1 described above. In this example, the configuration and operation of each of the processing units 2 to 15 other than the synthesizer unit 1 are the same as those described above. 2, the detailed configuration and operation of each of the processing units 2 to 15 other than the synthesizer unit 1 will not be described in this example.

An information processing device having substantially the same function as the information processing device connected to the reader / writer R2 shown in FIG. 2 is connected to the reader / writer R1 of this embodiment via an interface. The information processing apparatus according to the present embodiment includes, for example, information (frequency data) for specifying a carrier frequency in addition to the functions provided in the information processing apparatus connected to the reader / writer R2 shown in FIG. Is received from the user, and the received frequency data is transmitted to the reader / writer R1 via the interface. In this example, since the configuration of the information processing apparatus other than the function for receiving frequency data and the like as described above is the same as that connected to the reader / writer R2 shown in FIG. 2 above, The description is omitted.

The configuration and the like of the synthesizer section 1 provided in the reader / writer R1 of this embodiment will be described with reference to FIG. The synthesizer unit 1 shown in FIG. 1 includes a voltage-controlled oscillator (VCO) 2 for generating a carrier wave with a variable frequency.
1, a crystal oscillator 22 having a function of generating a signal of a fixed frequency using a crystal, and a PL controlling the VCO 21
An L synthesizer 23 and a loop filter 24 having a filter function are provided.
The synthesizer 23 and the loop filter 24 are connected in a ring to form a loop.

Here, the VCO 21 has a function of oscillating a carrier wave with a variable frequency as described above. In this embodiment, for example, the VCO 21 is provided with an input terminal for externally inputting a voltage value for frequency control. It has a function of oscillating a carrier having a frequency corresponding to the voltage value input from the input terminal, and outputting the oscillated carrier to the modulator 2 and the PLL synthesizer 23. In this example, the VCO 21 capable of generating carrier waves of various frequencies as described above constitutes an oscillator that generates a carrier wave with a variable frequency.

The PLL synthesizer 23 has a function of controlling the VCO 21 by setting a frequency specified by frequency data input from an external information processing device as an adjustment target, for example. VCO
By adjusting the voltage value output to the input terminal of the VCO 21 via the loop filter 24, the VCO 21 has a function of controlling the carrier wave of the frequency which is the adjustment target designated by the frequency data to be oscillated from the VCO 21. . In such an adjustment process, for example, a signal generated by the crystal oscillator 22 is used as a signal of the reference frequency, or the VCO 21
The adjustment is performed by comparing the frequency of the carrier input from the VCO with the frequency of the adjustment target to adjust the voltage value output to the VCO 21 or the like.

With such a configuration, the synthesizer unit 1
For example, when frequency data designating a frequency different from the frequency set as the adjustment target is input from outside, the adjustment target value of the frequency of the carrier generated from the VCO 21 is changed to a newly specified value. Thus, the frequency of the carrier output from the VCO 21 to the modulator 2 can be changed to a specified value.
Here, the carrier wave output to the modulator 2 is wirelessly transmitted from the antenna 5 via the transmission amplifier 3 and the circulator 4 as in the case of the reader / writer R2 shown in FIG. In R1, information is wirelessly communicated with the ID tag T1 via the carrier wave thus wirelessly transmitted.

In this embodiment, the PLL synthesizer 23 which controls the VCO 21 based on the frequency data described above is used.
Thus, an adjusting means for changing the oscillation frequency of the oscillator (VCO 21 in this example) according to an external input is configured. In this example, the above-described oscillator (in this example, VC
O21) and adjusting means (in this example, PLL synthesizer 2)
With the provision of 3), a carrier wave generating means for generating a carrier wave is configured.

As described above, in the reader / writer R1 of this embodiment, for example, the user operates a key or the like provided in an external information processing apparatus to input a carrier frequency to be adjusted to the information processing apparatus, and By transmitting the frequency data designating the specified carrier frequency from the information processing apparatus to the reader / writer R1, the setting of the synthesizer unit 1 provided in the reader / writer R1 is changed and the reader / writer R1 is changed.
1 can change the frequency of the carrier transmitted wirelessly.

Therefore, in the reader / writer of this embodiment, even when a plurality of reader / writers are installed adjacent to each other, for example, if the center frequencies and the like of the carrier waves wirelessly transmitted from the reader / writers are different from each other in such an installation. With this setting, it is possible to avoid the interference of the carrier wave between the reader / writers installed adjacently and to prevent the beat of the carrier wave or the like.

More specifically, the reader / writer of the present example is a case in which a system capable of identifying a plurality of ID tags at a time by installing a plurality of reader / writers adjacent to each other is configured. Also each reader / writer and ID
Normal information communication with the tag can be ensured, and the communication distance and area where information can be communicated between each reader / writer and the ID tag are reduced due to carrier wave interference. Can be prevented. In this example, the carrier to be wirelessly transmitted from the reader / writer is configured to be variable in order to prevent the interference of the carrier between the reader / writers installed adjacent to each other, but, for example, different carrier frequencies are fixedly set. A similar effect can be obtained by installing a plurality of reader / writers adjacent to each other.

Here, in the above-described embodiment, the configuration is shown in which the frequency of the carrier wave wirelessly transmitted from the reader / writer is changed by the user operating the information processing device connected to the reader / writer. A configuration in which a key or the like for changing the carrier frequency is provided in, for example, a reader / writer may be employed. The configuration of the oscillator (the VCO 21 in the above-described embodiment) and the adjusting means (the PLL synthesizer 23 in the above-described embodiment) provided in the reader / writer is essentially that the frequency of the carrier wave generated from the oscillator in response to an external input is adjusted. Any configuration that can be changed may be used.

Also, as a configuration of the entire reader / writer,
Not necessarily limited to those shown in the above embodiments,
Various configurations may be used. For example, in the above embodiment, the reader / writer and the information processing device are provided separately, but they may be configured as an integrated device. Also,
For example, various forms may be used as a wireless medium, an antenna, a communication method, or the like used for wirelessly communicating information with a reader / writer.

Although the case where the ID tag is used as the mobile information communication body for wirelessly communicating information with the reader / writer has been described above, the present invention is not limited to the ID tag.
Various mobile information communication bodies may be used. Further, in the above embodiment, the configuration has been described in which the power is transmitted via the carrier wave wirelessly transmitted from the reader / writer to the mobile information communication body, and the mobile information communication body receives the power via the carrier wave. The wireless power transmission from the mobile information communication body to the mobile information communication body may not be performed. For example, a configuration in which a battery or the like for supplying operating power to the inside of the mobile information communication body may be used.

In the above-described embodiment, the configuration has been described in which the mobile information communication body modulates the carrier wave wirelessly transmitted from the reader / writer and returns it, thereby wirelessly transmitting information from the mobile information communication body to the reader / writer. However, such a configuration is not necessarily used.For example, an oscillator that generates a carrier wave is provided in the mobile information communication body, and the mobile information communication body wirelessly transmits information to the reader / writer by modulating the carrier wave generated by the oscillator. A configuration such as transmission may be used.

[0050]

As described above, according to the reader / writer according to the present invention, when a carrier is generated from an oscillator and information is wirelessly communicated with a mobile information communication body such as an ID tag via the carrier, the oscillator is used. Because the frequency of the generated carrier can be changed, for example, even when a plurality of reader / writers are installed adjacent to each other, the frequency of the carrier transmitted wirelessly from each of these reader / writers is made different from each other. By doing so, it is possible to avoid carrier wave interference between adjacent reader / writers.

[Brief description of the drawings]

FIG. 1 is a diagram for describing a configuration example of a reader / writer and an ID tag according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a reader / writer and a configuration example of an ID tag according to a conventional example.

[Explanation of symbols]

1. Synthesizer, 2. Modulator, 3. Transmit amplifier, 4. Circulator, 5. Antenna,
21 voltage controlled oscillator, 22 crystal oscillator, 23
..PLL synthesizer, 24 loop filter
R1 reader reader / writer, T1 ID tag,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuzo Miura 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Company (72) Inventor Masatoshi Nagaishi 3-14-20 Higashinakano, Nakano-ku Tokyo Inside Electric Co., Ltd. LL16

Claims (1)

[Claims] 1. A reader / writer having means for generating a carrier wave and wirelessly communicating information with a mobile information communication body via the carrier wave, wherein the carrier wave generating means generates a carrier wave with a variable frequency. A reader / writer comprising: an adjusting unit that changes an oscillation frequency of an oscillator according to an external input.