JPH11298366A - Non-contact id tag system and data reception method in interrogator therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve response data detection sensitivity in a non-contact ID tag system and to enlarge the operatable area of a non-contact ID tag. SOLUTION: In a response data reception period, switches 21 and 23 are turned OFF and response data outputted from filters 9 and 12 are inputted to reception amplifiers 10 and 13 as they are and amplified. In the other period, the switches 21 and 23 are turned ON and input to the reception amplifiers 10 and 13 is attenuated. Thus, since large amplitude change outputted from the filters 9 and 12 is suppressed at the time of interrogation data transmission, even when the characteristics of the reception amplifiers 10 and 13 are set so as to sufficiently amplify the response data with less amplitude change, the saturation of the amplifier by interrogation data is prevented and the detection sensitivity of the response data is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a contactless ID tag system and a data receiving method in an interrogator thereof.

[0002]

2. Description of the Related Art A non-contact ID tag system transmits interrogation data from an interrogator on a carrier wave and transmits it from an antenna. The non-contact ID tag receives the data, extracts power from the carrier wave and supplies it to an internal circuit. And return response data to the question data. The return of the response data is performed by reflecting the received carrier wave.

FIGS. 2 and 3 are block diagrams showing the configuration of a conventional contactless ID tag system. FIG. 2 shows an interrogator, and FIG. 3 shows a contactless ID tag (responder). In FIG.
In the interrogator 100, the transmission carrier outputted from the synthesizer 1 is amplitude-modulated by the interrogator data by the modulator 2 and amplified by the transmission amplifier 3. Then, the signal is transmitted from the antenna 5 via the circulator 4.

[0004] The transmitted wave is received by the antenna 16 of the transponder 200 (non-contact ID tag) (FIG. 3) in the operable area, and is input to the modem 17. Modem 17
Extracts the power, clock and interrogation data from the carrier transmitted from the interrogator, and supplies the power to each circuit and the clock and interrogation data to the control unit. The control unit 18 reads and writes the data in the memory 19 according to the query data from the interrogator, performs related control, and outputs response data corresponding to the query data to the amplitude modulator 17. Here, the memory 19 is a non-volatile memory and holds ID data and the like. The modulator / demodulator 17 amplitude-modulates the carrier transmitted according to the response data from the control unit, and returns the carrier to the interrogator 100 as a reflected wave.

[0005] The carrier wave returned from the transponder is received by the antenna 5 of the interrogator 100 and input to the distributor 6 via the circulator 4 where it is split into two. One of the two divided carriers is directly input to the receiving system 2, and the other is phase-shifted by 90 ° by the phase shifter 7 and input to the receiving system 1.
In each reception system, the input carrier is mixed with the carrier from the transmission amplifier 3 by the mixers 8 and 11, baseband components are extracted by the filters 9 and 12, respectively, amplified by the reception amplifiers 10 and 13, and then combined. The signals are added and synthesized by the amplifier 14. This demodulation system uses two reception systems because in the case of one reception system, if the transmission carrier and the reception carrier are orthogonal, the response data cannot be demodulated. By phase-shifting one of the two received carrier waves by 90 °, the response data can always be detected stably by combining the outputs of the two receiving systems without taking phase synchronization with the received carrier wave. The demodulated response data is converted into digital data by the level converter 15 and output to a processing system (not shown).

[0006]

In the above-mentioned conventional system, since the carrier transmitted from the interrogator is used as it is as the local input of the mixer, while the interrogation data is being transmitted, the amplitude modulation by the interrogation data is performed. The signals having large amplitude changes are input to the receiving amplifiers 10 and 13. On the other hand, since the response data from the transponder is sent by electromagnetic coupling between the transponder and the interrogator antenna, even in the operable area of the non-contact ID tag, the fluctuation of the received carrier wave level at the interrogator is obtained. Therefore, the amplitude change due to the response data may have a small value at the input points to the receiving amplifiers 10 and 13. Therefore, it is necessary to provide the receiving amplifiers 10 and 13 with a gain that can sufficiently amplify the small amplitude change so that the response data can be detected with certainty. A problem arises in that the receiving amplifier is saturated at the time of transmission. For this reason, it is difficult to detect the response data, which is one of the factors that limit the operable area.

An object of the present invention is to provide a non-contact ID tag system capable of reliably detecting received response data without being affected by transmission inquiry data, and a data receiving method in the interrogator. is there.

[0008]

According to the present invention, there is provided a contactless ID tag system comprising: a contactless ID tag system comprising: A method of receiving data in an interrogator for detecting the response data from the return wave when the transmission wave is amplitude-modulated with response data to the inquiry data and returned as a return wave, wherein the return wave Are divided into two, and one of them is phase-shifted by 90 ° as a first reception wave, and the other half is defined as a second reception wave.
After mixing the reception wave with the transmission wave by the first and second mixers, respectively, the baseband component is extracted through the first and second low-pass filters, and the reception period of the response data is shorter than the reception period of the response data. Input each of the baseband components to the first and second receiving amplifiers via the first and second variable attenuators whose attenuation rates are controlled to be larger. The present invention provides a data receiving method in an interrogator, wherein the response data is detected by combining outputs.

Further, according to the present invention, the interrogator generates a carrier, modulates the amplitude with the interrogation data, and then amplifies and transmits the amplified signal.
A reception distributor for generating the phase-shifted first reception wave and the other second reception wave divided into two, and mixing the first reception wave and the second reception wave with the transmission wave output from the transmission unit. First and second detectors for extracting the reduced component,
The output of the first and second detection units is controlled such that the attenuation rate of the other reception periods is larger than the reception period of the response data from the non-contact ID tag. First and second variable attenuators, and the first and second variable attenuators
Non-contact ID tag, comprising: a first and a second receiving amplifier for amplifying the output of the variable attenuator of the first embodiment; and a combining unit for combining and outputting the outputs of the first and second receiving amplifiers. A control response unit for creating response data to the question data of the interrogator, extracting the question data from a transmission wave from the interrogator, sending the data to the control response unit, and responding from the control response unit. A modulation / demodulation unit for amplitude-modulating a transmission wave from the interrogator with data and returning the modulated wave to the interrogator is provided.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a configuration example of an interrogator of a contactless ID tag system according to the present invention. The same circuits as those in FIG. 2 showing the conventional configuration are denoted by the same reference numerals. The difference from FIG. 2 is that the input side of the reception amplifier 10 of the interrogator 101 is grounded via the resistor 20 and the switch 21, and the input side of the reception amplifier 13 is grounded via the resistor 22 and the switch 23. It is that you are. And switches 21, 2
3 is a reception control signal C given from a processing system (not shown).
The on / off is controlled by. Further, the non-contact ID tag is the same as that of the conventional FIG.

In the ID tag system, in order to reliably detect response data, it is desirable that transmission of question data and reception of response data do not overlap on a time axis.
The present invention is also directed to such a system. In a processing system (not shown) of the interrogator 101, the transmission period of the question data and the reception period of the response data are known, so that the processing system turns off the switches 21 and 23 during the reception period of the response data and the other periods A reception control signal C for turning on the switches 21 and 23 is output. Then, at the time of transmitting the question data, the switches 21 and 23 are turned on, and the input signals of the receiving amplifiers 10 and 13 are
0, 22 are installed. Therefore, the resistors 20, 2
If the resistance value of 2 is smaller than the input resistance of the receiving amplifiers 10 and 13, a large level change at the time of transmitting the inquiry data is attenuated, and the input of the receiving amplifiers 10 and 13 is reduced. When the response data is received, the switches 21 and 23 are turned off, so that the inputs of the receiving amplifiers 10 and 13 are not attenuated and are amplified as they are. Thus, the receiving amplifier 10,
Since the response data can be amplified using the whole of the 13 dynamic ranges, it is possible to reliably detect the response data.

In FIG. 1, the grounding circuit using one resistor is used to attenuate the input level of the receiving amplifier during periods other than the response data receiving period.
When it is necessary to consider the matching of the output of 12 and the matching of the input of the receiving amplifiers 10 and 13, a variable attenuation circuit that does not impair such matching may be used.

[0013]

According to the present invention, a large level change due to interrogation data can be suppressed and input to the receiving amplifier.
The dynamic range of the receiving amplifier can be sufficiently used, the response data can be reliably detected, and the operable area of the non-contact ID tag can be expanded.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of an interrogator of a conventional contactless ID tag system.

FIG. 3 is a block diagram illustrating a configuration of a non-contact ID tag.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Synthesizer 2 Modulator 3 Transmission amplifier 4 Circulator 5, 16 Antenna 6 Distributor 7 Phase shifter 8, 11 Mixer 10, 13 Receiving amplifier 14 Synthetic amplifier 17 Modulator / demodulator 18 Controller 19 Memory 20, 22 Resistor 21, 23 Switch 101 Interrogator 200 Transponder (non-contact ID tag)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masanori Asakusa 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Company

Claims (2)

[Claims] 1. A transmission wave amplitude-modulated by interrogation data from an interrogator of a non-contact ID tag system is received by a non-contact ID tag, and the transmission wave is amplitude-modulated by response data to the interrogation data to form a return wave. A data receiving method in an interrogator for detecting the response data from the returned wave when it is returned, wherein the returned wave is divided into two and one of the two is phase-shifted by 90 °. The other of the received wave and the other half is defined as a second received wave, and the first and second received waves are mixed with the transmitted wave by first and second mixers, respectively, and then mixed through the first and second low-pass filters. The baseband component is taken out, and the baseband component is passed through the first and second variable attenuators that are controlled so that the attenuation rate in the other reception periods is larger than the reception period of the response data. Each To the first and second
A data receiving method in an interrogator, wherein the response data is detected by inputting to the receiving amplifiers of (1) and (2), and combining the outputs of the two receiving amplifiers. 2. An interrogator, which generates a carrier wave, modulates the amplitude with the interrogation data, amplifies and transmits the amplified signal, and a first receiver which divides the received wave into two and shifts one of the two waves by 90 °. A reception distribution unit for generating the other second reception wave divided into two waves, and for extracting the reduced component by mixing the first reception wave and the second reception wave with the transmission wave output from the transmission unit. And the first and second detectors, wherein the first and second detectors are controlled such that the attenuation rate is larger in the other reception periods than in the response data reception periods from the non-contact ID tags. A first and a second variable attenuator receiving an output of the second detector as an input; a first and a second receiving amplifier for amplifying an output of the first and the second variable attenuator; And a combining unit for combining and outputting the output of the second receiving amplifier. A contactless ID tag, a control response unit for creating response data to the question data of the interrogator, extracting the question data from a transmission wave from the interrogator, sending the query data to the control response unit, and A modulation / demodulation unit for amplitude-modulating a transmission wave from the interrogator based on response data from a control response unit and returning the modulated wave to the interrogator.