KR20070047485A - Radio frequency identification reader - Google Patents

Abstract

RFID reader according to the present invention comprises a plurality of antennas; A first switching unit configured to switch the antennas to transmit and receive signals sequentially or in groups; And a second switching unit which separates the transmission / reception signal by switching the sequentially switched antennas to a reception processing stage or a transmission processing stage. In addition, the RFID reader according to the present invention is further characterized in that the control unit for transmitting a control signal of the switching operation to the first switching unit and the second switching unit is further provided, the antenna is arranged to the left and right of the area to which the electronic tag is moved. Or different angles of transmission and reception on each other on the region where the electronic tag is moved.

According to the present invention, since the antenna can communicate with the electronic tag in a wider area with a small number of antennas, the arrangement of the antennas is easy and the error rate, stability, The recognition distance can be improved and the installation cost can be reduced. In addition, according to the present invention, it is possible to easily design the processing structure of the transmission and reception signal, to reduce the probability of malfunction, and to reduce the RFID reader product size.

Description

RFID reader {Radio Frequency IDentification reader}

1 is a view schematically showing the components and connection form of a conventional RFID system.

2 is a view schematically showing the components and connection forms of an RFID system to which an RFID reader is applied according to an embodiment of the present invention.

3 is a block diagram schematically illustrating the components of an RFID reader according to an embodiment of the present invention;

4 is a block diagram schematically illustrating the components of an electronic tag for communicating with an RFID reader according to an embodiment of the present invention.

5 is a switching structure diagram of a first switching unit and a second switching unit according to an embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

210: RFID reader 212: RF processing stage

211a, 211b, 211c, and 211d: antenna 212a: first switching unit

212b: second switching unit 212c: RF transmission processing unit

212d: RF receiver 213: baseband processor

214: Q-RSSI circuit 215: I-RSSI circuit

216: control circuit 220: electronic tag

The present invention relates to an RFID reader, and more particularly, to a switching structure of an RFID reader having a plurality of antennas.

Currently, ubiquitous network technology has attracted the attention of many people, ubiquitous network technology means a technology that allows to naturally connect to various networks regardless of time and place.

As the next generation technology of the ubiquitous network technology, RFID technology may be cited. Among them, RFID technology introduced in commerce is representative.

In general, a commercial RFID system includes an electronic tag attached to a product and embedded with detailed information, and an RFID reader that reads the information of the electronic tag using RF communication, and the electronic tag attached to the product includes the RFID reader. As it passes through the area where it is located and transmits the information using RF communication, it provides a foundation for efficient logistics / distribution management such as distribution, assembly, price change, and sale of goods.

Meanwhile, a receiver of a conventional RFID reader is generally implemented through envelope detection using an amplitude shift keying (ASK) modulation scheme. According to the conventional design scheme, a data recognition rate is lowered because a bit error rate is lowered. There is this.

Therefore, the radio wave environment varies greatly depending on factors such as the position and speed at which the electronic tag passes through the antenna area of the RFID reader, and the packaging material (for example, pallet load) of the product with the electronic tag. According to the change, an error rate, stability, recognition distance, etc. of data received by the RFID reader may be different.

1 is a view schematically showing the components and connection form of the conventional RFID system 100, the conventional RFID system is a plurality of antennas (111, 112, 113, 114, 121, 122, 123, 124) and switches It comprises a plurality of RFID readers (110, 120) and the electronic tag 130 provided.

1, there are two RFID readers 110 and 120, two switches 115, 116, 125 and 126 and four antennas 111, 112, 113, 114, 121, 122, 123 and 124, respectively. Antennas are arranged on both sides with the moving region of the product with the electronic tag interposed therebetween.

The antenna is divided into a transmission and reception band, wherein the first antenna 111 and the second antenna 112 operate as a transmission antenna of the first RFID reader 110, and the third antenna 113 and the fourth antenna 114. Is operated as a reception antenna of the second RFID reader 120.

In addition, the fifth antenna 121 and the sixth antenna 122 is operated as a transmission antenna of the second RFID reader 120, and the seventh antenna 123 and the eighth antenna 124 are the second RFID reader 120. It is operated as a receiving antenna of.

The first antenna 111 and the second antenna 112 (or the fifth antenna 121 and the sixth antenna 122) are connected to the first switch 115 (or fourth switch 126), The first switch 115 (or the fourth switch 126) switches the transmission signal transmitted from the first Tx processing stage 117 (or the second Tx processing stage 128) to the first antenna 111 and the second antenna. The antenna 112 (or the fifth antenna 121 and the sixth antenna 122) alternately transmits the transmission signal.

The third antenna 113 and the fourth antenna 114 (or the seventh antenna 123 and the eighth antenna 124) are connected to the second switch 116 (or third switch 125), The second switch 116 (or the third switch 125) may receive a signal received from the third antenna 113 and the fourth antenna 114 (or the seventh antenna 123 and the eighth antenna 124). The switch is transferred to the first Rx processing stage 118 or the second Rx processing stage 127.

In this way, the antenna is divided into a transmission band and a reception band. Unlike other mobile communication systems, the RFID tag and the RFID reader transmit and receive signals using the same frequency band. This is because it has a structure that processes them separately.

Therefore, according to the conventional RFID system, since the structure for separating and processing the transmitted and received signals becomes complicated, there is a problem that the probability of malfunction occurs, and the size of the RFID reader increases.

In addition, since the antennas for transmitting and receiving are separated on one RFID reader 110 and 120, and the RFID readers 110 and 120 are also provided in plural, the total number of antennas is eight. Will increase.

In this configuration, the signals processed in the plurality of Rx / Tx processing stages provided in the first RFID reader 110 and the second RFID reader 120 must be divided and processed again in the baseband stage (not shown), Since signals processed from each RFID reader have to be separated and processed at the server side (not shown), there is a problem that the system implementation is complicated and the installation cost is increased.

In particular, even if the number of antennas is provided in a large number, there is a limit in the installation area of the antenna for processing the transmission signal and the reception signal (for example, according to FIG. The recognition rate of the tag is not significantly improved in the changing radio wave environment.

In order to overcome such environmental changes and lower the error rate of transmission / reception data, the design of the transmission / reception structure of the RFID system is recognized as an important aspect.

Accordingly, the present invention allows a single antenna to process both transmission and reception signals, and when a plurality of antennas for processing transmission and reception signals are provided, the switching operation is controlled to transmit transmission and reception signals in order at each position, thereby reducing the number of antennas. It is an object of the present invention to provide an RFID reader capable of communicating with an electronic tag in a wider area with an antenna.

In order to achieve the above object, the RFID reader according to the present invention includes a receiving processing stage and a transmitting processing stage, a plurality of antennas; A first switching unit configured to switch the antennas to transmit and receive signals sequentially or in groups; And a second switching unit for separating the transmission and reception signals by switching the sequentially switched antennas to the reception processing stage or the transmission processing stage.

In addition, the RFID reader according to the present invention further includes a control unit for transmitting a control signal of a switching operation to the first switching unit.

In addition, the control signal processed in the RFID reader according to the present invention includes one or more of period information and order information of the switching operation.

In addition, the antenna provided in the RFID reader according to the present invention is disposed to the left and right of the region in which the electronic tag is moved.

In addition, the antenna provided in the RFID reader according to the present invention is arranged with different radio wave transmission and reception angles on the region in which the electronic tag is moved.

In addition, the first switching unit or the second switching unit of the RFID reader according to the present invention is provided with a switching device chip.

In addition, the first switching unit or the second switching unit of the RFID reader according to the present invention is provided as a coupler.

In addition, the first switching unit or the second switching unit of the RFID reader according to the present invention is a switching circuit implemented by a combination of a phase shifter, a passive element and a diplexer or duplexer.

Hereinafter, an RFID reader according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. An RFID reader according to an embodiment of the present invention is used in a logistics system.

2 is a view schematically showing the components and the connection form of the RFID system 200 to which the RFID reader 210 is applied according to an embodiment of the present invention.

Referring to FIG. 2, the RFID system 200 according to an embodiment of the present invention includes an RFID reader 210 and an electronic tag 220 including a plurality of antennas 211a, 211b, 211c, and 211d. 220 is attached to the goods passing through the logistics inspection area, the antennas 211a, 211b, 211c, 211d are arranged to the left and right of the area (inspection area) to which the electronic tag 220 is moved.

In the embodiment of the present invention, four antennas 211a, 211b, 211c, and 211d are provided, and two antennas are arranged to the left and right of the moving area of the electronic tag 220. In this case, each antenna may be installed with different radio wave transmission and reception angles.

As described above, the RFID reader 210 according to the embodiment of the present invention is provided as one, unlike the prior art, it is possible to control a plurality of antennas for transmitting and receiving signals.

3 is a block diagram schematically showing the components of the RFID reader 210 according to an embodiment of the present invention.

Referring to FIG. 3, the RFID reader 210 according to the embodiment of the present invention includes four antennas 211a, 211b, 211c, and 211d, an RF processing stage 212, a baseband processing stage 213, and a control circuit 216. ), A Q-RSSI circuit 214, and an I-RSSI circuit 215. The RF processing stage 212 includes a first switching unit 212a, a second switching unit 212b, and an RF transmission processing unit. 212c and an RF reception processing unit 212d.

The first switching unit 212a of the RF processing stage 212 performs a switching operation so that four antennas 211a, 211b, 211c, and 211d may be sequentially connected to the second switching unit 212b. The order in which the antennas 211a, 211b, 211c, and 211d are operated may be combined in various ways.

In this case, since the first switching unit 212a performs a switching operation several times or more than ten times per second, the antennas may have the effect of simultaneously monitoring the entire region in which the electronic tag 220 is moved.

In addition, when the second switching unit 212b is connected to any one of four antennas 211a, 211b, 211c, and 211d connected to the first switching unit 212a, the second switching unit 212b transmits a transmission signal to the RF transmission processing unit 212c. In this case, the transmission and reception signals are separated and transmitted by performing a switching operation according to the case where the signal is transmitted from the antenna side to the antenna side and the case where the received signal is transmitted from the antenna side to the RF receiving processor 212d.

As such, the first switching unit 212a and the second switching unit 212b are interlocked so that the antennas 211a, 211b, 211c, and 211d simultaneously process the transmission / reception signals while simultaneously moving the moving region of the electronic tag 220. You can watch.

The first switching unit 212a and the second switching unit 212b may be implemented in various forms, for example, SP4T (Single-Pole Quadruple-Throw, 4: 1 MUX / DEMUX), SPDT (Single-Pole) Double throw) may be implemented as a switching element, but may be implemented in the form of a phase shifter, a switching circuit, a coupler, or the like implemented by a combination of a passive element and a diplexer or a duplexer.

The RF receiving processor 212d includes a low noise amplifier, a band pass filter, a matching circuit, and the like, suppresses and amplifies noise components of the received signal transmitted from the first switching unit 212a and the second switching unit 212b. The amplified signal is transmitted to the baseband processor 213.

The RF transmission processor 212c adjusts and amplifies the power gain of the transmission signal transmitted from the baseband processor 213, filters the mixed signal in the process of processing the received signal, and transmits the mixed signal to the second switching unit 212b. do.

The baseband processing stage 213 is connected to the RF transmission processing unit 212c and the RF reception processing unit 212d, respectively, and is composed of two parts for processing a transmission signal and a reception signal (components of the baseband processing stage 213). (Not shown), an I / Q demodulator, a low pass filter (LPF), an intermediate frequency amplifier, a modulator, an A / D converter, and the like are provided to process the received signal. Q signal separation / low frequency signal generation, filtering, amplification / modulation and A / D conversion.

The baseband processing stage 213 may include a D / A converter, a low pass filter, a demodulator, an intermediate main gain amplifier, an intermediate frequency filter, and the like to process digital signals into intermediate frequency signals and RF signals. The signal is converted into a signal, and the gain of the power is adjusted and transmitted to the RF transmission processor 212c.

The digital signal transmitted from the baseband processing stage 213 is transferred to the control circuit 216, the I-RSSI circuit 215, and the Q-RSSI circuit 214.

The I-RSSI circuit 215 is a circuit for measuring the reception strength of an in-phase (I) signal. Usually, the I-RSSI circuit 215 detects and corrects that the signal strength increases and becomes irregular due to interference or mixed noise components. Means a circuit used for the purpose.

The Q-RSSI circuit 214 measures a reception strength of a quadrature (Q) signal and performs a function similar to that of the I-RSSI circuit 215.

The control circuit 216 is provided with a communication protocol to control wireless communication with the electronic tag 220, and periodically sends an information request signal to determine the position of the electronic tag 220.

In addition, the control circuit 216 analyzes the code of the tag identification information received from the electronic tag 220 and demodulated by the baseband processing stage 213, in which the data format is converted and filtering is performed to extract necessary information. Process.

Here, the control circuit 216 may be a field programmable gate array (FPGA) circuit or a digital signal processing (DSP) circuit.

The FPGA circuit refers to a gate array circuit (logical integrated circuit) that can be added to the programming if necessary to implement the function of the RFID reader 210 outside the production process of the chip, the gate array and PLD (Programmable Logic Devices) ) Is implemented.

These FPGA circuits have the advantages of being able to use multiple I / Os like a gate array, programmable at a time, and increasing the utility of the gate by 95%.

The DSP (Digital Signal Processing) circuit processes algebraic operations on digital data obtained by converting analog signals to analog / digital (A / D) conversion and performs signal processing such as filtering and spectral analysis.

The DSP circuit is basically for real-time digital processing of analog signals, which is a mathematical operation semiconductor that can quickly and digitally process digital signals, and a microprocessor performs these functions but specializes only in mathematical operations. Slower than a circuit

As such, the DSP circuit is a dedicated processor that pursues high speed and compactness, and when the DSP circuit is used, the system can be upgraded by replacing only software.

4 is a block diagram schematically illustrating the components of an electronic tag 220 that communicates with an RFID reader 210 according to an embodiment of the present invention.

Referring to FIG. 4, the electronic tag 220 includes a tag antenna 221, a reception demodulator 222, a transmission modulator 224, a power supply unit 223, a control unit 225, and a memory 226. do.

The tag antenna 221 receives an information request signal through a wireless channel or transmits processed tag identification information. Usually, a dipole antenna is used.

The power supply unit 223 is a device for supplying power to the reception demodulation unit 222, the control unit 225 and the transmission modulator 224. The electronic tag 220 is classified into an active method and a passive method according to the driving method of the tag antenna 221 and the power supply unit 223. For example, the electronic tag 220 and the RFID reader 210 In the active mode, UHF signals with a frequency band of 400 MHz to 960 MHz are used.

The reception demodulation unit 222 demodulates the incoming information request signal into digital data and transmits the received information request signal to the control unit 225. The control unit 225 analyzes a code of the demodulated information request signal to provide tag identification information. Create

In addition, the control unit 225 has a communication protocol to control wireless communication with the RFID reader 210. In this case, the memory 226 stores the information code system, and the control unit 225 generates the tag identification information using the same.

The transmission modulator 224 modulates the generated tag identification information into an RF signal, and the modulated tag identification information is transmitted to the RFID reader 210 through a tag antenna 221.

5 is a diagram illustrating a switching structure of the first switching unit 212a and the second switching unit 212b according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the first switching unit 212a has four signal paths connecting the four antennas 211a, 211b, 211c, and 211d to the second switching unit 212b. The control voltage terminals Vctl1 and Vctl2 to which the control signal (voltage) is applied, and the power supply terminal Vcc for supplying power to the switch are provided.

In addition, the first switching unit 212a includes a high frequency switching circuit that can be implemented in various forms as described above, and includes a decoder that interprets the control voltage and logically controls the switching operation.

The control circuit 216 has a program in which cycle information, order information, etc. of the switching operation is reflected, and executes the program to send a control signal to the control voltage terminal of the first switching unit 212a.

The second switching unit 212b has two signal paths connecting the first switching unit 212a, the RF transmission processing unit 212c, and the RF reception processing unit 212d, and is the same as the first switching unit 212a. A control voltage terminal Vctl3, a power supply terminal Vcc, a high frequency switching circuit, a decoder, and the like are provided.

The control circuit 216 grasps input paths of the transmission signal and the reception signal, generates a control signal, and transfers the generated control signal to the second switching unit 212b.

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible that are not illustrated above. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the RFID reader according to the present invention, since an antenna can communicate with an electronic tag in a wider area with a small number of antennas, the arrangement of the antennas is easy and the error rate and stability of transmission / reception data according to the change of the radio wave environment Stability, recognition distance, etc. can be improved, and installation cost can be reduced.

In addition, according to the present invention, since a single RFID reader can efficiently control a plurality of antennas, it is possible to easily design a transmission / reception signal processing structure, reduce the probability of malfunction, and improve the RFID reader product size. There is an effect that can be reduced.

In addition, according to the present invention, since sufficient isolation is ensured by reducing the propagation influence between the transmission signal and the reception signal through the switching unit, the transmission and reception performance can be improved.

Claims (8)

An RFID reader comprising a receiving end and a transmitting end, A plurality of antennas; A first switching unit configured to switch the antennas to transmit and receive signals sequentially or in groups; And And a second switching unit which separates a transmission / reception signal by switching the sequentially switched antennas to the reception processing stage or the transmission processing stage. The method of claim 1, RFID reader, characterized in that further provided with a control unit for transmitting a control signal of the switching operation to the first switching unit. The method of claim 2, wherein the control signal is RFID reader, characterized in that it comprises one or more of period information, order information of the switching operation. The method of claim 1, wherein the antenna RFID reader, characterized in that arranged in the left and right of the area to which the electronic tag is moved. The method of claim 1, wherein the antenna RFID reader, characterized in that arranged on the area where the electronic tag is moved with different radio transmission and reception angles. The method of claim 1, wherein the first switching unit or the second switching unit RFID reader, characterized in that provided as a switching device chip. The method of claim 1, wherein the first switching unit or the second switching unit RFID reader, characterized in that provided as a coupler. The method of claim 1, wherein the first switching unit or the second switching unit RFID reader, characterized in that the switching circuit implemented by a combination of a phase shifter, a passive element and a diplexer or duplexer.

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