KR101189400B1 - Radio Frequency IDentification reader - Google Patents

Abstract

RFID reader according to the invention a plurality of antennas; A plurality of phase shifters respectively connected to the antennas and having different phase differences; And an RF processing unit connected to the phase shifter and having a switch unit for switching the phase shifters individually or in groups to sequentially conduct electricity with one transmission path.

According to the present invention, by applying a phase change for each antenna and switching the phase-converted signal again in time, it is possible to accommodate a multi-band frequency signal and to ensure a high recognition rate to maintain a stable transmission and reception state of the signal In addition, the conversion range of the AD converter can be widely used, and the saturation phenomenon caused to the receiving end can be prevented in amplifying the signal.

Description

RFID reader {Radio Frequency IDentification reader}

1 is a view schematically showing some components of a conventional RFID reader.

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

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

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

5 is a diagram illustrating an internal structure of a switch circuit of an RFID reader according to an embodiment of the present invention.

Description of the Related Art

100: RFID reader 110: antenna unit

111 to 118: antenna 1 to antenna 8 120: RF receiver

122: Rx phase shift circuit 122a to 122d: first to fourth phase shifters

124: first switch circuit 126: first band pass filter

128: low noise amplifier 130: baseband receiver

140: control unit 150: RF transmitter

152: Tx phase shift circuit 152a to 152d: fifth to eighth phase shifters

154: second switch circuit 156: second band pass filter

158: power amplifier 160: baseband transmitter

The present invention relates to a RFID (Radio Rrequency IDentification) reader, and to an RFID reader for increasing the transmission and reception efficiency of the RFID signal through the antenna.

Nowadays, ubiquitous network technology is attracting attention of many people. Ubiquitous network technology means a technology that makes it possible to connect to various networks smoothly regardless of time and place.

The ubiquitous network technology can be implemented in various ways using communication technologies such as telematics communication, short-range wireless communication, and mobile communication, and by using this, a natural connection environment is provided in a space such as a car, home, or public place. The utilization of IT information and technology will increase, and the overall IT industry is expected to develop more rapidly.

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

Generally, a commercial RFID system includes an RFID tag attached to a product and embedded with detailed information, an RFID reader that reads the information of the electronic tag using RF communication, an information server that collects information from the RFID reader, and builds a database. The RFID tag attached to the product passes through the area where the RFID reader is located and transmits information by using RF communication, so the logistics / distribution management such as distribution, assembly, price change, and sale of the product can be efficiently handled. Provides a foundation to be

On the other hand, the receiving end of the conventional RFID reader, it is common to be implemented through the envelope detection using ASK (Amplitude Shift Keying), FSK (Frequency Shift Keying), PSK (Phase Shift Keying) modulation scheme, According to the present invention, there is a disadvantage in that the data recognition rate is lowered because the bit error rate is lowered.

Since the RFID reader targets a tag moving at a high speed, a change in the radio wave environment is severe, and a change in the reception signal is greatly caused by an external environment change.

1 is a view schematically showing some components of a conventional RFID reader 10. According to FIG. 1, a conventional RFID reader 10 includes an antenna 12 and a low noise amplifier (LNA) 14 ), A summer 16, and a baseband portion 18.

The antenna 12 receives an RF signal transmitted from a tag through a wireless channel in the 800 MHz to 900 MHz band, for example, in which the RF signal is affected by factors such as propagation attenuation, multipath loss, interference, and Doppler effect. To various signal components.

The antenna 12 is provided in plural to receive signals whose characteristics are differentiated according to the radio wave environment, and each antenna 12 receives various signals.

That is, since the strength of the signal is weak and the recognition rate is changed due to the characteristics of the conventional RFID reception method, the antenna has a structure for accommodating each signal through the plurality of antennas 12 and utilizing the same to improve the recognition rate of the data.

The low noise amplifier 14 is also provided in plural and connected to each antenna 12, and amplifies the filtered RF signal while suppressing the low noise component.

The adder 16 collects the amplified RF signals, sums them, and transfers them to the baseband unit 18 to increase the recognition rate of the data by reflecting the maximum signal components.

That is, since the characteristics of the signal required by the RF receiver are not phases but phases, the signals are summed to increase the accuracy of the phases. As a result, the strength of the RF signal received in real time becomes irregular (for example, too large or small), Since the baseband portion 18 occupies only a part of the voltage range processed, the conversion efficiency is reduced.

This uses only a part of the dynamic processing range of the AD converter of the baseband unit 18, which means that the conversion range of the AD converter is smaller.

In addition, when the gain having a constant value is multiplied and amplified in the low noise amplifier 14, an RF signal having an irregular size may have a high probability of causing a receiver saturation phenomenon.

The present invention has a multi-band (multi-mode) structure that accommodates a variety of frequency types and specifications due to the radio wave characteristics of the RFID tag and the RFID reader, and the reception method, so that the recognition rate can be stably maintained using a plurality of antennas. Provided is an RFID reader having an improved signal processing structure.

RFID reader according to the invention a plurality of antennas; A plurality of phase shifters respectively connected to the antennas and having different phase differences; And an RF processing unit connected to the phase shifter and having a switch unit for switching the phase shifters individually or in groups to sequentially conduct electricity with one transmission path.

In addition, the RF processing unit of the RFID reader according to the present invention a filter connected to the switch unit; And an RFID receiver including an amplifier connected to the filter.

In addition, the RF processing unit of the RFID reader according to the present invention a filter connected to the switch unit; And an RFID transmitter including an amplifier connected to the filter.

In addition, the RFID reader according to the present invention is provided with a control unit for transmitting a control signal of the switching operation to the switch unit, the control signal by the control unit includes one or more information of the cycle information and the order information of the switching operation.

In addition, the RFID system according to the present invention includes an RFID tag; And an RFID reader including an RFID transmitter and receiver including a plurality of antennas, a plurality of phase shifters, a switch unit, a filter, and an amplifier, wherein one or more antennas of a transmitter and a receiver of the RFID reader are provided on one side and the other. One or more different antennas are provided on the side of the transmitter and the receiver.

Hereinafter, an RFID transceiver according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, wherein the RFID transceiver is an RFID reader.

2 is a block diagram schematically illustrating components of an RFID reader 100 according to an embodiment of the present invention.

2, the RFID reader 100 according to the embodiment of the present invention includes an antenna unit 110, an RF receiver 120, an RF transmitter 150, a baseband receiver 130, a baseband transmitter 160, and It comprises a control unit 140, the antenna unit 110 is provided with a total of eight antennas (111 to 118), two groups (111 to 114, 115 to 118 with four antennas as a group) ) Are connected to the RF receiver 120 and the RF transmitter 150, respectively.

The RF receiver 120 includes a first phase shift circuit (PS) 122, a first switch circuit 124, a first band pass filter 126, and a low noise amplifier 128. 150 includes a second phase shift circuit 152, a second switch circuit 154, a second band pass filter 156, and a power amplifier 158.

The first phase shift circuit 124 and the second phase shift circuit 154 are each provided with four phase shifters 122a through 122d and 152a through 152d, and have a total of eight phase shifters 122a and 122b. , 122c, 122d, 152a, 152b, 152c, and 152d have a configuration connected to the eight antennas 111 to 118 described above.

Phase shifters 122a through 122d and 152a through 152d separate the signals by generating a phase difference between two or more frequency signals, either electrically or physically. For example, concentrated elements such as inductors and capacitors. The phase difference can be generated by using a (Lumped element) to generate a phase difference electrically or by changing the physical length of the line (by using a distributed element).

Normally, the phase shifters 122a through 122d and 152a through 152d are implemented using microstriplines, and assuming that the frequency signals in the 900 MHz band are processed, the microstriplines are "λ / It is 4 "long. Here, "λ / 4" means a length of about 22 mm and can also be interpreted as having a phase difference of about 90 degrees.

In the embodiment of the present invention, the first phase shifter 122a is 0 °, the second phase shifter 122b is 90 °, and the third phase shifter 122c is 180 °, and the fourth phase shifter 122 ( 122d) has a phase difference of 270 °.

In addition, the second phase shift circuit 152 also has the same configuration and function as the first phase shift circuit 122, and the fifth phase shifter 152a is 0 ° and the sixth phase shifter 152b. Is 90 °, the seventh phase shifter 152c has 180 °, and the eighth phase shifter 152d has a phase difference of 270 °.

Accordingly, the first phase shift circuit 122 and the second phase shift circuit 152 form various phase differences when the received signal or the transmitted signal is received or transmitted through the antennas 111 to 118. Recognition rate is improved.

The first switch circuit 124 performs a switching operation so that the phase shifters 122a to 122d of the first phase shift circuit 122 may be sequentially connected to the first band pass filter 126. The second switch circuit 154 performs a switching operation so that the phase shifters 152a to 152d of the second phase shift circuit 152 may be sequentially connected to the second band pass filter 156.

In this case, the first switch circuit 124 and the second switch circuit 154 receives a control signal including period information and (antenna) order information from the controller 140 to perform a switching operation, thereby performing a switching operation. The order and time at which the two antennas 122a to 122d and the second group of four antennas 152a to 152d are operated may be combined in various ways.

In addition, since the first switch circuit 124 and the second switch circuit 154 performs a switching operation several times or more than a dozen times per second, the antennas 111 to 118 simultaneously monitor the entire area where the RFID tag is moved. Can be seen.

The first band pass filter (BPF) 126 filters the signal of the noise component mixed in the RFID received signal on the first switch circuit 124, and the second band pass filter 156 supplies power. The amplifier 158 filters the signal of the noise component mixed in the RFID transmission signal.

The low noise amplifier (LNA) 128 suppresses the signal of the noise component as much as possible from the RFID received signal, amplifies the signal of a size that can be processed by the baseband receiver 130, and the power amplifier 158 The power is amplified so that the RFID transmission signal converted by the baseband transmitter 160 can be transmitted by the RF transmitter 150.

The baseband receiver 130 and the baseband transmitter 160 include a phase synchronization circuit, a mixer, a balun circuit, a filter, an amplifier, an A / D (or D / A) converter (these components are not shown), and the like. The baseband receiver 130 mixes the RF signal with the oscillation frequency signal, converts the RF signal into a baseband signal, converts the digital signal into an analog signal (AD), and transmits the digital signal to the control unit 140.

The baseband transmitter 160 receives the digital signal from the controller 140 and converts the digital to analog (DA) signal into a baseband signal, converts the baseband signal into an oscillation frequency signal, and converts the signal into an RFID transmission signal. do.

The controller 140 defines an RFID transmission protocol, a data packet protocol, and the like to control communication with the RFID tag, and processes the RFID signal converted into a digital signal in an application program layer to interpret corresponding information.

In addition, the control unit 140 sets the cycle information and the order information of the switching operation in the memory, generates a control signal including the same, and transmits the first switch circuit 124 and the second switch circuit 154 to the transmission signal. The control signal may be sent to leave the first switch circuit 124 in the idle state in the case of processing or to leave the second switch circuit 154 in the idle state in the case of processing the received signal.

3 is a view schematically showing the components and the connection form of the RFID system to which the RFID reader 100 is applied according to an embodiment of the present invention.

Referring to FIG. 3, four antennas 111, 115, 112, 116 and 118, 114, 117, and 113 are arranged on both sides of the RFID tag 200, and on one side, the RF receiver 120 is provided. And two antennas 111 and 112 connected to each other and two antennas 115 and 116 connected to the RF transmitter 150 are disposed to be mixed, and the other side also has two antennas 113 and 114 connected to the RF receiver 120. ) And two antennas 117 and 118 connected to the RF transmitter 150 are disposed in a mixed state.

According to the present invention, since the phase shifters 122a to 122d and 152a to 152d connected to each of the antennas 111 to 118 all have different phase differences, such an antenna arrangement design can be usefully used. If there is a metal wall A on which side the 200 proceeds, an antenna (eg, third antenna: 113) receiving a signal directly from the RFID tag 200 and a signal reflected on the metal wall (that is, a physical phase difference occurs) Between the antennas (for example, the fourth antenna: 114) receiving the received signal, mutual interference may occur and be distorted into a signal that cannot be interpreted by the controller 140.

In this case, according to the present invention, by applying a switchable length type (Switchable length type), the phase shifters (122a to 122d, 152a to 152d) has the effect of correcting the signal by generating a phase difference in the received signal, the switch Circuits 124 and 154 separate the signals back on the time axis, greatly reducing the probability of the signal being distorted.

4 is a block diagram schematically illustrating components of an RFID tag 200 for communicating with an RFID reader 100 according to an embodiment of the present invention.

Referring to FIG. 4, the RFID tag 200 includes a tag antenna 210, a reception demodulator 220, a transmission modulator 240, a power supply unit 230, a tag controller 250, and a memory 260. do.

The tag antenna 210 receives the information request signal or transmits the signal processing tag identification information through the wireless channel, and usually a dipole antenna is used.

The power supply unit 230 is a device for supplying power to the reception demodulation unit 220, the tag control unit 250 and the transmission modulator 240.

The RFID tag 200 is classified into an active method and a passive method according to the driving method of the tag antenna 210 and the power supply unit 230. In the active method, the tag antenna 210 generates an oscillation circuit. And transmit the tag identification information, and the power supply unit 230 is provided with a battery to provide power to the oscillation circuit.

In addition, the passive method is a method in which the power supply unit 230 regenerates power by using radio wave energy of the RF signal transmitted from the RFID reader 100, and the detector diode is rectified and rectified to a DC voltage using the RF signal. The DC voltage is used as a power source for supplying a modulation waveform to the transmission modulator 240 by generating a response code.

When the RFID tag 200 and the RFID reader 100 operate in an active manner, a UHF signal having a frequency band of 400 MHz to 900 MHz is used (here, 433 MHz is used), and when the RFID tag 200 and the passive reader operate, the UHF (800 MHz) is used. ~ 900 MHz, national assigned frequency) signal is used.

The reception demodulation unit 220 demodulates the received information request signal into digital data and transmits the received information request signal to the tag control unit 250. The tag control unit 250 analyzes a code of the demodulated information request signal to identify a tag. Generate information. In addition, the tag controller 250 includes a communication protocol to control wireless communication with the RFID reader 100.

The memory 260 stores an information code system, and the tag control unit 250 generates the tag identification information using the information code system. The information code system includes header information, reader identification information, error correction information, article information, and device identification. Information and the like.

The transmission modulator 240 modulates the generated tag identification information into an RF signal, and transmits the modulated tag identification information through the tag antenna 210.

5 is a diagram illustrating the internal structure of the switch circuit 124, 154 of the RFID reader 100 according to an embodiment of the present invention.

Referring to FIG. 5, the first switch circuit 124 connected to the first phase shifters 122a to the fourth phase shifters 122d, and the fifth phase shifters 152a to the eighth phase shifters 152d. The second switch circuit 154 is connected to the first phase shifter 122a to the eighth phase shifter 152d are connected to the first antenna 111 to the eighth antenna 118, respectively. have.

The first switch circuit 124 and the second switch circuit 154 is different from that provided in the RF receiver 120 and RF transmitter 150, the basic connection configuration and operation is the same, so the first switch circuit 124 Will be described as an example.

The first switch circuit 124 has four signal paths connecting the four antennas 111, 112, 113, and 114 to the first bandpass filter 126, and controls to selectively open and close these signal paths. Control voltage terminals Vctl1 and Vctl2 to which a signal (voltage) is applied, and a power supply terminal Vcc for supplying power to the switch.

In addition, the first switch circuit 124 includes a high frequency switching circuit that can be implemented in various forms such as a semiconductor device, a microstrip line coupler, a combination circuit of a lumped device, and the like to interpret the control signal and logically perform a switching operation. It includes a decoder to control.

The control unit 140 has a program in which cycle information, order information, etc. of the switching operation is reflected as described above. The control unit 140 executes the program to generate a control signal, and the control voltage terminals Vctl1, of the first switch circuit 124. To Vctl2).

The controller 140 detects an input path of a transmission signal and a reception signal, generates a control signal, and transfers the generated control signal to the first switch circuit 124 and the second switch circuit 154.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications not illustrated in the drawings are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

According to the RFID reader according to the present invention, by varying the phase for each antenna and switching the phase-converted signal again in time, it is possible to accommodate the multi-band frequency signal and ensure a high recognition rate to maintain a stable transmission and reception state of the signal It can be effected.

In addition, according to the present invention, it is possible to improve the efficiency by utilizing a wider conversion range of the AD converter, it is possible to prevent the saturation phenomenon caused to the receiving end in amplifying the signal.

Claims (6)

A plurality of antennas; A plurality of phase shifters respectively connected to the antennas and having different phase differences; And an RF processing unit connected to the phase shifter and having a switch unit to switch the phase shifters individually or in groups to sequentially conduct electricity with one transmission path. The method of claim 1, wherein the RF processing unit A filter connected to the switch unit; And RFID reader including an amplifier connected to the filter. The method of claim 1, wherein the RF processing unit A filter connected to the switch unit; And And an RFID transmitter including an amplifier connected to the filter. The method of claim 1, And a control unit for transmitting a control signal of the switching operation to the switch unit. The method of claim 4, wherein the control signal is And at least one of periodic information and order information of the switching operation. RFID tag; And Including an RFID reader including a plurality of antennas, a plurality of phase shifter, a switch unit, a filter, an amplifier transmitting and receiving unit, One or more antennas of the transmitter and the receiver of the RFID reader are provided on one side and at least one other antenna of the transmitter and the receiver on the other side.

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