JP2001177435A - Contactless id tag system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contactless ID tag system with enhanced user-friendliness that can accurately receive ID data with excellent reception sensitivity by discriminating a weak electric field from a strong electric field so as to select its reception gain different from a conventional contactless ID tag system having had a problem of being unable to accurately read data because an amplification factor of a reception amplifier is fixed. SOLUTION: In the contactless ID tag system, a responder 2 transmits ID data with an error check code added thereto, and an interrogator 1 uses a reception amplifier 20 having a gain adjustment function provided with a reception gain for a weak electric field and with a reception gain for a strong electric field in advance and selects other electric field reception gain than the setting reception gain depending on error detection contents of the error check code by a gain control means 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact ID tag system used in an entry control system and the like, and more particularly to a non-contact ID tag capable of accurately receiving ID data with good reception sensitivity and improving usability. About the system.

[0002]

2. Description of the Related Art First, an outline of a general non-contact ID tag system will be described with reference to FIG.
I will explain using. FIG. 4 is a schematic configuration diagram of a general non-contact ID tag system. A general non-contact ID tag system will be described using an entry management system as an example. As shown in FIG. 4, for example, an interrogator 1 'fixedly installed at the entrance of a room for performing entry control and a mobile unit This is a system carried by a certain occupant and communicating with a transponder (ID tag) 2 'responding to a question from the interrogator 1'.

[0003] Specifically, when a visitor carrying the transponder 2 'approaches the entrance of the room where the interrogator 1' is installed and enters the service area of the interrogator 1 ', the interrogator 1' ′ Senses the transponder 2 ′ and transmits an interrogation radio wave, and the transponder 2 ′ receiving the interrogation radio returns the ID data written in the transponder 2 ′ to the interrogator 1 ′, The interrogator 1 ′ identifies the transponder 2 ′ or the person carrying the transponder 2 ′ with the returned ID data, for example, inquires with the ID data permitting entry into the room in advance, for example. The door of the room is unlocked when there is.

Here, when the transponder 2 'returns the ID data, the location near the antenna of the transponder 2' is a weak electric field area where the electric field is weak, and it moves away from the antenna and approaches the antenna of the interrogator 1 '. As the electric field increases, the electric field gradually increases and becomes a strong electric field area.

Next, details of a conventional non-contact ID tag system will be described with reference to FIG. FIG. 5 is a configuration block diagram of a conventional contactless ID tag system. FIG.
Here, only the part of the interrogator 1 for transmitting and receiving data is shown. As shown in FIG. 5, the conventional non-contact ID tag system basically includes an interrogator 1 'and a transponder (ID tag).
2 '.

The interrogator 1 'is provided with a synthesizer 11
, Modulator 12, transmission amplifier 13, and circulator 1
4, an antenna 15, a distributor 16, and a phase shifter 17
, A mixer A18a and a filter A1 forming a receiving system A
9a, a receiving amplifier A20a ', a mixer B18b, a filter B19b, and a receiving amplifier B20 constituting a receiving system B.
b ', a synthesis amplifier 21 and an A / D converter 22.

[0007] The transponder 2 ′ includes an antenna 30,
It comprises a modem 31 ′, a controller 32 and a memory 33.

Next, each part constituting the interrogator 1 'of the conventional contactless ID tag system will be described. The synthesizer 11 generates a transmission carrier. The modulator 12 generates a transmission wave by applying amplitude modulation to a transmission carrier from the synthesizer 11 with interrogation data input from the control system according to a clock input from a control system (not shown). The transmission amplifier 13 is a general amplifier that amplifies the transmission wave output from the modulator 12 and outputs the amplified transmission wave to the circulator 14. The circulator 14 outputs a transmission wave from the transmission amplifier 13 to the antenna 15 and outputs a reception wave from the antenna 15 to the distributor 16 so that transmission and reception can be shared and switched by one antenna. . Antenna 15
Is a general antenna for transmitting and receiving wireless signals, wirelessly transmitting a transmission wave from the circulator 14 to the transponder 2 ',
Conversely, it receives a radio signal transmitted from the transponder 2 '.

The splitter 16 outputs an input signal to a plurality of systems. In order to split the received wave transmitted from the transponder 2 'and received by the antenna 15, the received wave is distributed to the receiving system A and the receiving system B.
The received wave input from the circulator 14 is
7 and the mixer B 18b of the receiving system B.

The phase shifter 17 shifts the phase of the input signal and outputs the shifted signal. The phase shifter 17 shifts the phase of the received wave input from the distributor 16 by 90 ° and mixes the received signal with the mixer A 18 of the receiving system A.
b.

In a transponder 2 ', which will be described later, there is no oscillator inside, and a received carrier of a received radio signal is transmitted as it is as a transmission carrier. Depending on the relationship, in the interrogator 1 ′, the phase difference between the transmitted carrier and the received radio signal is 180 °
In this case, since demodulation cannot be performed, two demodulating means, a receiving system A and a receiving system B, are provided, and by shifting the phase of each other by 90 °, even if one receiving system cannot demodulate, , And demodulated by another receiving system.

Next, a mixer A 18a constituting the receiving system A
The filter A19a, the receiving amplifier A20a ', and the mixer B18b, the filter B19b, and the receiving amplifier B20b' that constitute the receiving system B are completely the same, and will be described as the mixer 18, the filter 19, and the receiving amplifier 20 '. . The mixer 18 demodulates the received radio signal, mixes the transmission wave (transmission carrier) from the transmission amplifier 13 and the received radio signal, and outputs the difference to the filter 19 as a data wave of ID data (response data). Output. This is because, in a transponder 2 ′ to be described later, the carrier contained in the transmission wave from the interrogator 1 ′ is held as it is and used as a transmission carrier when transmitting ID data. The response data is demodulated by mixing the transmission carriers in the device 1 '.

The filter 19 removes unnecessary components of the data wave of the demodulated ID data. The filter 19 removes unnecessary components of the ID data wave input from the mixer 18 and outputs the same to the receiving amplifier 20 '. I have.

The receiving amplifier 20 'amplifies the ID data wave with a fixed amplification factor to a level which can be easily processed.
The ID data wave input from the filter 19 is amplified and output to the synthesis amplifier 21.

Here, a specific example of the receiving amplifier 20 'of the conventional non-contact ID tag system will be described with reference to FIG. FIG. 6 is a circuit diagram showing a specific example of the receiving amplifier 20 'of the conventional contactless ID tag system. FIG. 6A is an example of a circuit using a transistor, and FIG. 6B is an example of a circuit using an operational amplifier.

The combining amplifier 21 combines ID data waves of the receiving system A and the receiving system B. The combining amplifier 21 combines ID data waves input from the receiving amplifiers 20 'of the receiving system A and the receiving system B to form an analog signal. Is output.

The A / D converter 22 converts an analog signal into a digital signal. The A / D converter 22 converts the ID data wave of the analog signal input from the synthesizing amplifier 21 into an I / D signal of the digital signal.
The data is converted to D data and output to a control system (not shown) for inquiring ID data and the like.

Next, each part constituting the transponder 2 'of the conventional contactless ID tag system will be described. Antenna 3
Numeral 0 denotes a general antenna for transmitting and receiving a radio signal, which receives a radio signal transmitted from the interrogator 1 'and transmits a radio signal of response data such as ID data to the interrogator 1'. I have.

When receiving the radio signal transmitted from the interrogator 1 ', the modem 31' demodulates the radio signal to extract interrogation data, and holds the transmission carrier from the interrogator 1 '. The power and clock are extracted from the transmission carrier, the power is supplied to the memory 33 and the controller 32, and the clock and the interrogation data are output to the controller 32. When the response data is transmitted from the transponder 2 ', the ID data output from the controller 32 applies amplitude modulation to the held carrier transmitted from the interrogator 1'.

The controller 32 controls the transponder 2 ', reads out the ID data stored in the memory 33 in response to the interrogation data input from the modem 31', and responds to the ID data. Processing for transmitting the data to the interrogator 1 'is performed.

The memory 33 is a nonvolatile memory in which ID data and the like are registered in advance.

Next, the operation of the conventional contactless ID tag system will be described with reference to FIG. In the interrogator 1 ′, when interrogation data is input from a control system (not shown), the modulator 12 modulates the transmission carrier output from the synthesizer 11 with the interrogation data to generate a transmission wave, and transmits the transmission wave. The signal is amplified by the amplifier 13 and transmitted from the antenna 15 through the circulator 14.

Then, the transmission wave of the interrogation data transmitted from the interrogator 1 'is received by the antenna 30 of the transponder 2', and the power is extracted from the reception wave by the modem 31 '.
It is supplied to the controller 32 and the memory 33. Further, the received wave is demodulated by the modem 31 ', interrogation data and a clock are extracted, output to the controller 32, and the carrier is held.

The question data is analyzed by the control unit 32. If the question data is an inquiry data for inquiring the ID data, the ID data is read from the memory 33, output to the modem 31 ', and held as the ID data. The modulated carrier is subjected to amplitude modulation to generate a response data transmission wave, which is transmitted from the antenna 30 to the interrogator 1 '.

The transmission wave of the response data is received by the interrogator 1 ′ at the antenna 15 and output to the distributor 16 via the circulator 14.

The received wave of the response data (ID data) is distributed by the distributor 16 to the receiving system A and the receiving system B. In the receiving system A, the phase is shifted by 90 ° by the phase shifter 17 and output to the mixer A 18a. In the receiving system B, the data is output to the mixer B 18b as it is.

Similarly, the receiving system A and the receiving system B
Transmission wave (transmission carrier wave) from the transmission amplifier 13
And the received wave of the response data (ID data) received are mixed to extract the ID data, the unnecessary wave is removed by the filter 19, and the reception amplifier 20 'amplifies the signal with a fixed amplification factor to a level that can be easily handled. .

The ID data output from the receiving amplifiers 20 ′ of the receiving system A and the receiving system B are combined by the combining amplifier 21, converted from an analog signal to a digital signal by the A / D converter 22, and the ID data is output. You.

As a prior art of the non-contact ID tag system, Japanese Patent Application Laid-Open No. 11-2
No. 98366, “Non-contact ID tag system and data receiving method in interrogator” (Applicant: Kokusai Electric Inc.,
Inventor: Yuzo Miura et al.) This prior art is a contactless ID tag system that amplifies with a sufficient amplification factor in a receiving amplifier during a response data receiving period, and attenuates an input to the receiving amplifier during periods other than the response data receiving period. This can prevent the receiving amplifier from being saturated due to the above, and can increase the detection sensitivity of the response data.

[0030]

However, in the above-mentioned conventional non-contact ID tag system, the gain of the receiving amplifier 20 'is fixed, and the transponder 2' is located in the strong electric field area of the antenna 15 of the interrogator 1 '. There is a problem that data may not be accurately read depending on whether the user enters the area or the weak electric field area.

More specifically, for example, if the transponder 2 'is aimed at when the interrogator 1' is in the strong electric field area of the antenna of the interrogator 1 'and the amplification factor of the receiving amplifier 20' is set to be small, When the transponder 2 'is located in the weak electric field area, the response data may not be accurately read due to noise or the like. Conversely, when the transponder 2 'is in the weak electric field area of the antenna of the interrogator 1', it is aimed and the amplification factor of the receiving amplifier 20 'is set to be relatively large. When in the strong electric field area, even a very small noise is amplified and recognized as data, and the response data may not be accurately read.

That is, since the amplification factor is fixed, accurate response data can be obtained only in either the strong electric field or the weak electric field. Therefore, the amplification factor is specified and set depending on the application, and the interrogator is used on the side of use. There is a problem that the user has to pay attention to the distance between the telephone and the transponder to avoid trouble from the operation side, and is inconvenient to use.

In order to eliminate the inconvenience of use, a method of providing two types of amplification factor systems and switching between the two systems may be considered in some cases. However, the scale of the apparatus is increased, which is uneconomical.

[0034] The present invention has been made in view of the above-mentioned circumstances, and determines and switches between a weak electric field and a strong electric field, can accurately receive ID data with good reception sensitivity, and can improve usability. The purpose is to provide a system.

[0035]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a transponder for transmitting ID data to which an error detection code is added, a reception gain for a weak electric field and a reception gain for a strong electric field. A non-contact ID tag system comprising an interrogator that holds the reception gain and switches the set reception gain to another electric field reception gain in accordance with the content of the error detection by the error detection code. The ID data can be accurately received with the sensitivity, and the usability can be improved.

The present invention for solving the above-mentioned problems of the prior art is characterized in that a transponder for transmitting ID data, a reception gain for a weak electric field and a reception gain for a strong electric field are held in advance, and the reception level of the ID data is reduced. The contactless ID tag system includes a display and an interrogator for switching the set reception gain to another electric field reception gain by a gain control signal input according to the reception level. The ID data can be accurately received, and the usability can be improved.

[0037]

Embodiments of the present invention will be described with reference to the drawings. Note that the function realizing means described below may be any circuit or device as long as the function can be realized, and some or all of the functions may be realized by software. is there. Further, the function realizing means may be realized by a plurality of circuits, or the plurality of function realizing means may be realized by a single circuit.

In general, the non-contact ID tag system according to the present invention adds an error detection code and
A transponder for transmitting data, holding the reception gain for the weak electric field and the reception gain for the strong electric field in advance, and changing the set reception gain to another electric field reception gain according to the error detection content by the error detection code. Since the interrogator is provided with a switching interrogator, the reception gain is switched to an appropriate reception gain in accordance with the content of the error detection, the ID data can be accurately received with good reception sensitivity, and the usability can be improved.

In the non-contact ID tag system according to the present invention, in the non-contact ID tag system according to the present invention, the transponder receives a radio wave for interrogating the ID from the memory for storing the ID data, and receives the ID data from the interrogator. An ID data transmitting means for adding an error detection code to the ID data, wherein the interrogator transmits a radio wave for asking an ID; a receiving means for receiving the ID data; Amplifying means for holding the gain and the reception gain for the strong electric field, switching the reception gain set according to an external gain control signal to another reception gain for the electric field, and amplifying the received ID data;
Gain control means for performing data error detection and outputting a gain control signal for switching the gain in the amplification means in accordance with the content of the error detection, wherein the reception gain can be switched in accordance with the error detection result of the received ID data Therefore, the reception gain is switched to an appropriate reception gain in accordance with the content of the error detection, so that the ID data can be accurately received with good reception sensitivity, and the usability can be improved.

Further, in the contactless ID tag system according to the present invention, the transponder has a memory for storing the ID data and an ID data transmission for transmitting the ID data by receiving a radio wave for interrogating the ID from the interrogator. Means, and the interrogator has an ID
Means for transmitting a radio wave for inquiring about, reception means for receiving the ID data, reception in advance holding the reception gain for the weak electric field and the reception gain for the strong electric field, and the reception set according to an external gain control signal. Amplifying means for amplifying received ID data by switching the gain to another electric field reception gain, reception level display means for displaying the reception level of the received ID data, and gain for switching the gain in the amplification means according to the reception level A gain control means for outputting a control signal, wherein the reception gain is switched according to the reception level of the received ID data. Data can be received accurately and usability can be improved.

Here, the ID data transmitting means of the transponder corresponds to the controller 32, the modulator / demodulator 31 and the antenna 30 in FIG. 1, and the interrogator transmitting means corresponds to the synthesizer 11, the modulator 12, The amplifier 13 corresponds to the circulator 14 and the antenna 15, and the receiving unit corresponds to the antenna 15, the circulator 14, the distributor 16, the phase shifter 17, the mixer 18, and the filter 19, and the amplifying unit corresponds to the receiving amplifier 20 having a gain adjustment function. Correspondingly, the reception level display means comprises the level converter 23 and the reception level display 2
It corresponds to 4.

First, the configuration of the contactless ID tag system of the present invention will be described with reference to FIG. FIG. 1 is a configuration block diagram of a contactless ID tag system according to the present invention.
Parts having the same configuration as in FIG. 5 are described with the same reference numerals. The non-contact ID tag system of the present embodiment basically includes an interrogator 1 and a transponder 2 as in the conventional non-contact ID tag system.

The interrogator 1 includes a synthesizer 11 and a part similar to those of the conventional non-contact ID tag system.
Modulator 12, transmission amplifier 13, circulator 14
, Antenna 15, distributor 16, phase shifter 17
, A synthesis amplifier 21, and an A / D converter 22. Further, as a characteristic part of the present invention, a reception amplifier A20a with a gain adjustment function is used instead of the mixer A18a, the filter A19a, and the conventional reception amplifier A20'a. A receiving system A provided, a receiving system B provided with a receiving amplifier B20b with a gain adjusting function instead of the mixer B18b, the filter B19b, and the conventional receiving amplifier B20'b; a new level converter 23; A display 24 and gain control means 25 are provided.

The transponder 2 is basically the same as the conventional non-contact ID tag system, and comprises an antenna 30, a modem 31, a controller 32, and a memory 33, except that The operation of the modulator / demodulator 31 is slightly different from that of the conventional modem 31 '.

Next, each part of the transponder 2 of the non-contact ID tag system according to the present invention will be specifically described. The antenna 30, the controller 32, and the memory 33 are the same as those in the conventional art, and thus will be described. The description will be omitted, and only the features of the present invention will be described.

When receiving the radio signal transmitted from the interrogator 1, the modulator / demodulator 31 is the same as the conventional one, and the description is omitted. When transmitting ID data from the transponder 2, an error detection code (CRC data) for detecting a reception error in the interrogator 1 is added to the ID data output from the controller 32 to generate response data. This is to apply amplitude modulation to the held carrier transmitted from the interrogator 1 using response data.

Next, each part of the interrogator 1 of the contactless ID tag system of the present invention will be specifically described. A synthesizer 11, a modulator 12, a transmission amplifier 13, a circulator 14, an antenna 15, a distributor 16, a phase shifter 17, a synthesis amplifier 21, an A / D converter 22,
The mixer A 18a and the filter A 19a of the receiving system A, and the mixer B 18b and the filter B 19b of the receiving system B are the same as those in the related art, and the description is omitted.

Next, the configuration of the characteristic part of the interrogator 1 of the contactless ID tag system of the present invention will be specifically described.
The receiving amplifier 20 with a gain adjusting function is provided instead of the conventional receiving amplifier 20 ', and has a receiving gain (amplification factor).
This is a receiving amplifier with a gain adjusting function circuit that can control the receiving gain, and switches the receiving gain according to a gain control signal output from a gain control unit 25 described later. Specifically, the receiving amplifier 20 with the gain adjusting function of the present invention
Then, as the reception gain, a reception gain for increasing the amplification factor for a weak electric field (referred to as reception gain for a weak electric field) and a reception gain for decreasing the amplification factor for a strong electric field (referred to as a reception gain for a strong electric field)
And two types of receiving gains are switched according to the gain control signal.

A specific example of the receiving amplifier 20 with a gain adjusting function of the contactless ID tag system of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing a specific example of the receiving amplifier 20 with a gain adjusting function of the contactless ID tag system of the present invention. FIG. 2A is a circuit example in the case of using a transistor. FIG. 2B is a circuit example when an operational amplifier is used. Receiving amplifier 20 with gain adjustment function
Is the gain control means 2 as shown in FIGS.
5. When the gain control signal from 5 is instructed to set for the strong electric field, the switch is turned on to lower the gain, and when instructed to be set for the weak electric field, the switch is turned off and the gain is turned off. Is to rise.

The level converter 23 receives an analog signal output from the synthesizing amplifier 21, converts the level of the input analog signal into a display level on a reception level display 24, and outputs the display level. Level converter 2
As for the output of No. 3, when the antenna 30 of the transponder 2 approaches the interrogator 1, a high level output is obtained, and when the antenna 30 is apart, the level decreases.

The reception level display 24 displays the level of the received signal. Specifically, the level of the analog signal input from the level converter 23 is represented by one or a plurality of L levels.
The information is displayed on a display such as an ED. For example,
The threshold value for determining whether the transponder 2 is in the weak electric field area or the strong electric field area of the antenna of the interrogator 1 is set in advance as a threshold value, and the level of the analog signal input from the level converter 23 is set to the threshold value. If it is larger, the LED is turned on because it is in the strong electric field area, and if the level of the analog signal input from the level converter 23 is equal to or less than the threshold, the LED is turned off because it is in the weak electric field area. .
Alternatively, a plurality of LEDs may be provided, and the LEDs may be turned on by the number corresponding to the level.

The gain control means 25 is a means for controlling the reception gain in the reception amplifier 20 with a gain adjustment function. Specifically, the gain control means 25 receives the reception response data output from the A / D converter 22 and inputs the reception response data into the reception response data. An error detection is performed on the included CRC data, and a gain control process for outputting a gain control signal according to the error detection result is performed. When there is no error in the gain control process, the ID data in the received response data is output to a control system (not shown).

Next, the gain control processing in the gain control means 25 of the contactless ID tag system of the present invention will be described with reference to FIG. FIG. 3 is a flowchart showing the flow of the gain control process in the gain control means of the contactless ID tag system of the present invention. In the gain control process in the gain control means 25 of the contactless ID tag system of the present invention, the reception gain is increased by the gain control signal to set for the weak electric field (100), and the ID data reading process for reading the ID data is performed (102). ). Here, the ID data reading process is
Instruct the control system (not shown) to send the question data,
Response data (ID data + CRC data) from the responder 2 to the query data is received, and the A / D converter 22
This is the process of receiving output from.

Then, the CRC in the received response data
A CRC check is performed using the data (104), and it is determined whether or not there is an error (106). If there is no error (No), the process proceeds to step 120. If there is an error (Yes), The reception gain is reduced by the gain control signal and set for a strong electric field (110).

Then, the ID data reading process is performed again (112), and the ID data is output (120).
Return to 00.

Next, the operation of the contactless ID tag system of the present invention will be described. In the contactless ID tag system of the present invention, as an initial state, a gain control signal for increasing the reception gain by the gain control means 25 of the interrogator 1 and setting it for a weak electric field is output, and the reception amplifier 20 with the gain adjustment function is weak. Set for electric field.

When the interrogator 1 senses that the transponder 2 has come near, for example, interrogation data for inquiring about the ID is transmitted to the transponder 2. When the interrogator 2 receives the interrogation data, power is obtained from the received wave by the modem 31, supplied to the controller 32 and the memory, and the carrier of the received wave is held. Then, the question data is sent to the controller 3
2, the controller 32 reads out the ID data stored in the memory 33, and the modulator / demodulator 31 reads out the ID data.
CRC data for error detection is added to the data and transmitted to the interrogator 1 as response data.

When the response data is received by the interrogator 1, as a result of demodulation, the response data is output from the A / D converter 22 to the gain control means 25, and the gain control means 25 converts the CRC data in the response data into a CRC. If a check is made and there is no error, the gain control means 25 outputs ID data to a control system (not shown).

On the other hand, if there is an error as a result of the CRC check in the gain control means 25,
, A gain control signal for lowering the reception gain and setting for the strong electric field is output, and the reception amplifier 20 with the gain adjustment function is switched to the strong electric field.

Then, again, the interrogator 1 transmits the interrogation data to the transponder 2, and the transponder 2 converts the ID data into a CRC.
The response data to which the data is added is transmitted to the interrogator 1,
When the interrogator 1 receives the response data, the gain control means 2
5, the ID data is read, and the read ID is read.
The data is output to a control system (not shown), and a gain control signal for increasing the reception gain and setting for a weak electric field is output from the gain control means 25 again.
Is returned for the weak electric field.

At this time, in the interrogator 1, the response data output from the synthesis amplifier 21 is level-converted by the level converter 23 in accordance with the reception level indicator 24, and the reception level of the response data is changed to the reception level. It is displayed on the display 24. For example, when the interrogator 1 and the transponder 2 approach each other, the reception level increases, so that the LED is turned on. When the interrogator 1 and the translator 2 are separated, the reception level decreases, and the LED turns off.

In the above description, the normal state is set for the weak electric field, and when an error occurs, the setting is switched to the strong electric field. On the contrary, the normal state is set for the strong electric field. When an error occurs, switching to the weak electric field may be performed.

In the above description, the transponder 1 transmits response data obtained by adding CRC data to ID data, and the interrogator 2 determines the gain control based on the result of the CRC check of the response data received by the gain control means 25. Although the signal is described as being controlled, a gain control signal is controlled from the display result of the reception level display 24 in the interrogator 2 as a system for switching the reception gain without changing the configuration of the conventional transponder 1 '. A system that switches the reception gain (amplification factor) of the reception amplifier 20 with the gain adjustment function is also conceivable.

According to the non-contact ID tag system of the embodiment of the present invention, in the interrogator 1, the reception gain (amplification factor) of the reception amplifier 20 with the gain adjustment function is usually weak by the control of the gain control means 25. The responder 2 responds to the question data transmitted from the interrogator 1 by setting the ID for the electric field.
Interrogator 1 sends response data with CRC data added to the data
The interrogator 1 performs a CRC check on the CRC data in the response data by the gain control means 25. In the case of an error, the gain of the reception amplifier 20 with the gain adjustment function is increased by the gain control signal for a strong electric field. It is switched, and the question data is transmitted to the transponder 2 again.
Since the response data from the interrogator 2 is received, it is not necessary to adjust the reception gain of the interrogator 2 for the strong electric field area or the weak electric field area. There is an effect that ID data can be accurately received with good reception sensitivity without being conscious, the usability can be improved, and applications can be expanded.

Further, according to the non-contact ID tag system of the present invention, the interrogator 2 displays the reception level of the response data on the reception level display 24, and the reception amplifier with the gain adjustment function corresponding to the reception level. Since the reception gain (amplification factor) of the interrogator 20 is switched between for the weak electric field and for the strong electric field, the reception gain of the interrogator 2 is not adjusted for the strong electric field area or for the weak electric field area. The carrier does not need to be aware of the range of the strong electric field area and the weak electric field area,
There is an effect that ID data can be accurately received with good reception sensitivity, usability can be improved, and applications can be expanded.

[0066]

According to the present invention, the transponder transmits ID data to which an error detection code is added, and the interrogator holds the reception gain for the weak electric field and the reception gain for the strong electric field in advance and performs error detection. Depending on the content of error detection by the code, the contactless ID tag system switches the set reception gain to another electric field reception gain, so that the reception gain is switched by determining the weak electric field / strong electric field by error detection, I with good receiving sensitivity
There is an effect that D data can be received accurately and usability can be improved.

According to the present invention, the transponder transmits the ID data, the interrogator previously holds the reception gain for the weak electric field and the reception gain for the strong electric field, displays the reception level of the ID data, and displays the reception level of the ID data. The contactless ID tag system switches the set reception gain to another electric field reception gain according to the gain control signal that is input according to the received signal. , The ID data can be accurately received with good reception sensitivity, and the usability can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a contactless ID tag system according to the present invention.

FIG. 2 is a circuit diagram showing a specific example of a receiving amplifier with a gain adjustment function of the contactless ID tag system of the present invention.

FIG. 3 is a flowchart showing a flow of a gain control process in a gain control means of the contactless ID tag system of the present invention.

FIG. 4 is a schematic explanatory view of a conventional non-contact ID tag system.

FIG. 5 is a configuration block diagram of a conventional non-contact ID tag system.

FIG. 6 is a circuit diagram showing a specific example of a receiving amplifier of a conventional contactless ID tag system.

[Explanation of symbols]

1 ', 1 ... Interrogator, 2', 2 ... Transponder, 11 ... Synthesizer, 12 ... Modulator, 13 ... Transmission amplifier, 1
4 circulator, 15 antenna, 16 distributor, 17 phase shifter, 18a mixer A, 18
b: Mixer B, 19a: Filter A, 19b: Filter B, 20a ': Receiving amplifier A, 20a: Receiving amplifier A with gain adjustment function, 20b': Receiving amplifier B, 2
0b: Receive amplifier B with gain adjustment function, 21: Synthetic amplifier, 22: A / D converter, 23: Level converter,
24: reception level display, 25: gain control means, 3
0 antenna, 31 ', 31 modulator / demodulator, 32 controller 33 memory

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuo Funakubo 3-14-20 Higashinakano, Nakano-ku, Tokyo F-term in Kokusai Electric Co., Ltd. 5B058 CA17 YA11

Claims (3)

[Claims] 1. A transponder for transmitting ID data to which an error detection code is added, and a reception gain for a weak electric field and a reception gain for a strong electric field are held in advance. A non-contact ID tag system, comprising: an interrogator that switches the set reception gain to another electric field reception gain. 2. A transponder for transmitting ID data, a reception gain for a weak electric field and a reception gain for a strong electric field, which are stored in advance.
An interrogator for displaying a reception level of the D data and for switching a set reception gain to another electric field reception gain by a gain control signal input according to the reception level. ID tag system. 3. The transponder is a transponder which operates in response to a radio wave for interrogating an ID from the interrogator, and responds by transmitting ID data to the interrogation of the ID. The non-contact ID tag system according to claim 1 or 2, wherein the interrogator is an interrogator that transmits a radio wave for asking an ID.