Description

RFID ANTENNA MODULE AND RFID READER/WRITER

HAVING THE SAME

Technical Field

[1] The present invention relates to a radio frequency identification (RFID) reader, and more particularly, to a RFID reader including an antenna module, which can realize a high performance even when a plurality of antennas is included. Background Art

[2] In recent years, active research has been done on RFID systems. FIG. 1 is a block diagram showing a general RFID system. The RFID system includes a transponder 110 called a RF tag, an antenna 120 for transmitting/receiving radio signals to/from the transponder 110, and a reader (and/or a writer) 130 for processing signals transmitted to or received from the antenna 120. Further, the reader 130 is connected to a host 140 for transmitting or receiving signals to or from one or more readers. The transponder 110 is attached to subjects to be identified such as products, vehicles, human bodies and animals, and stores data such as identification information about subjects and status information about subjects. Through this construction, the reader 130 transmits electromagnetic waves through the antenna 120 and activates the transponder 110, and reads data stored in the transponder 110 or record new data into the transponder 110. Further, data is gathered by the host 140 and processed according to a required method by the host 140.

[3] The RFID system has been applied to logistics management, etc. FIG. 2 is a view showing this conventional RFID system. In the conventional RFID system, in particular, a logistics management RFID system, a plurality of RFID tags 230 is attached to subjects for identification and moved on a conveyer belt C. To identify the plurality of moving RFID tags 230, a plurality of transmitting antennas 22Ot, 222t and 224t and a plurality of receiving antennas 22Or, 222r and 224r are connected to a RFID reader 210.

[4] The transmitting antennas 22Ot, 222t and 224t transmit signals, received from the reader 210, to the tags 230, thus activating the tags 230 and making the tags 230 transmit specific data. The data transmitted by the tags 230 is received by the receiving antennas 22Or, 222r and 224r and then transmitted to the reader 210, which processes and transmits the received data.

[5] The transmitting antennas 22Ot, 222t and 224t and the receiving antennas 22Or, 222r and 224r are connected to the reader 210 through a transmission line and transmit or receive signals to or from the reader 210. However, in general, when signals are

transmitted through a transmission line, transmission loss is generated, degrading the read performance of the reader 210. Thus, there is limit to the distance between the antenna and the reader 210.

[6] Further, when a plurality of antennas is installed, the respective antennas are deployed at different distances from the reader 210 considering radio wave environment, the position of tags, and so. Thus, the lengths of transmission lines from the reader 210 between the antennas are all different and transmission loss of signals transmitted/received through the transmission lines is also different. Consequently, a plurality of signals transmitted/received from the reader 210 through the antennas experiences transmission loss differently. Accordingly, a problem arises because the read performance of the reader 210 is degraded or a signal process becomes difficult.

[7] To solve the problems, a method of increasing transmission power of the reader has been taken into consideration. However, this method has a problem in that it is restricted by the performance of the reader itself and also cannot satisfy required effective isotropic radiated power (EIRP) on all the transmission lines. There is another method employing a high-performance transmission line or a plurality of readers. However, this method is problematic in that it increases the system construction cost. Disclosure of Invention Technical Problem

[8] Accordingly, an object of the present invention has been made to overcome the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a RFID antenna module and a RFID reader including the same, which can realize an excellent read performance irrespective of the distance between a reader and antennas in a RFID reader system including a plurality of the antennas. Technical Solution

[9] To accomplish the above object, according to one aspect of the present invention, there is provided a RFID antenna module disposed spaced apart from a RFID signal processing module and adapted to communicate with the RFID signal processing module, wherein the RFID antenna module includes an antenna, and modulation means for modulating a signal to be transmitted to the antenna.

[10] Preferably, the antenna module receives a digital signal, and the modulation means converts the digital signal into an analog signal.

[11] The antenna module further includes demodulation means for demodulating a signal received by the antenna. The antenna module outputs a digital signal, and the demodulation means converts an analog signal into the digital signal.

[12] To accomplish the above object, according to another aspect of the present invention, there is provided a RFID reader system, including one or more RFID

antenna modules and a RFID signal processing module communicating with the RFID antenna modules, wherein the antenna module includes an antenna, and modulation means for modulating a signal to be transmitted to the antenna. The antenna module is disposed spaced apart from the RFID signal processing module.

[13] Preferably, the antenna module receives a digital signal, and the modulation means converts the digital signal into an analog signal.

[14] The antenna module further includes demodulation means for demodulating a signal received by the antenna. The antenna module outputs a digital signal, and the demodulation means converts an analog signal into the digital signal.

[15] The one or more antenna modules communicate with the signal processing module using signals having different phases. The RFID reader system further includes a phase splitter connected between the one or more antenna modules and the signal processing module and configured to provide the one or more antenna modules with the signals having different phases.

Advantageous Effects

[16] As described above, according to the present invention, there are provided a RFID antenna module and a RFID reader including the same, which can realize an excellent read performance irrespective of the distance between a reader and antennas in a RFID reader system including a plurality of the antennas.

Brief Description of the Drawings

[17] FIG. 1 is a view showing a conventional RFID system;

[18] FIG. 2 is a view showing a conventional RFID system including a plurality of antennas; [19] FIG. 3 is a view showing a RFID system in accordance with an embodiment of the present invention; [20] FIG. 4 is a block diagram showing the RFID reader system in accordance with an embodiment of the present invention; [21] FIG. 5 is a block diagram showing a detailed construction of an antenna module in accordance with an embodiment of the present invention; and [22] FIG. 6 is a block diagram showing a RFID reader system in accordance with another embodiment of the present invention.

Best Mode for Carrying Out the Invention [23] Detailed embodiments of the present invention will now be described with reference to the attached drawings, but are only illustrative. The present invention is not limited to the embodiments.

[24] In the specification and claims, unless limited otherwise herein, the term "communication" is used to refer to the entire actions that transmit, receive, and/or transmit/

receive signals, information, data, and so on. In the specification and claims, unless limited otherwise herein, the term "reader" is used to refer to the inclusion of means for reading information from RFID tags, means for writing information into RFID tags, and means for both writing and reading information.

[25] FIG. 3 is a view showing a RFID system in accordance with an embodiment of the present invention. The RFID system of the present invention includes RFID tags 330, RFID antenna module 320, 322 and 324, and a RFID signal processing module 310. The RFID tags 330 are attached to identification subjects. The RFID antenna module 320, 322 and 324 transmit signals to the RFID tags 330 or receive signals from the RFID tags 320 through communication with the RFID tags 330. The RFID signal processing module 310 transmits processed signals to the RFID antenna module 320, 322 and 324 or processes signals, received from the antenna module 320, 322 and 324, and transmits the processed signals to an addition apparatus, such as a middleware, through communication with the RFID antenna module 320, 322 and 324.

[26] The RFID system of the present embodiment includes one or more antenna module

320, 322 and 324. The antenna module 320, 322 and 324 are deployed with them being spaced apart from the RFID signal processing module 310. That is, the antenna module 320, 322 and 324 are included in a separate apparatus from the RFID signal processing module 310 or protected by a separate housing from the RFID signal processing module 310, and disposed at different locations from the RFID signal processing module 310. Further, the antenna module 320, 322 and 324 can be placed at different distances from the signals processing module 310 and connected to the RFID signal processing module 310 through transmission lines.

[27] Meanwhile, each of the antenna module 320, 322 and 324 of the present embodiment includes specific signal processing means, unlike the conventional antenna. More specifically, the antenna module of the present embodiment can include modulation means that modulates signals to be transmitted to an antenna and/or demodulation means that demodulates signals received by an antenna. As described above, since each of the antenna module 320, 322 and 324 includes the signal processing means, loss at the transmission line can be minimized, or a signal process at the RFID signal processing module 310 is not degraded in spite of loss at the transmission line.

[28] Hereinafter, detailed embodiments of the antenna module and the RFID signal processing module are described with reference to FIGS. 4 and 5.

[29] FIG. 4 is a block diagram showing the RFID reader system in accordance with an embodiment of the present invention.

[30] Although only one antenna module is illustrated in the drawing for convenience sake, it will be evident to those having ordinary skill in the art that a plurality of

antenna modules can be included.

[31] The antenna module 320 of the present embodiment includes an antenna 410, a modulator 420 and a demodulator 430. The antenna 410 is constructed to have a specific resonant frequency in order to transmit/receive radio signals to/from RFID tags. A concrete resonant frequency can be decided according to a pertinent communication standard. The antenna 410 can consist of a circular polarization antenna in order to transmit/receive signals to/from tags disposed at various angles. This is disclosed in Korean Patent Applications Nos. 10-2005-0124396, 10-2006-0047997, 10-2006-0097849 and 10-2007-0016000 all of which were filed by the present applicant.

[32] The modulator 420 is connected to the antenna 410 and modulates signals to the antenna 410. That is, the modulator 420 modulates signals to be transmitted to tags through the antenna, thus increasing the communication distance between the antenna and the tags and enhance communication accuracy between the antenna and the tags. Further, the modulator 420 makes different signals, which are input thereto through the antenna 410, and signals input to the antenna module 320, thus increasing the communication distance between the antenna module 320 and the RFID signal processing module 310 and enhancing communication accuracy between the antenna module 320 and the RFID signal processing module 310. The demodulator 430 demodulates modulated signals received from the antenna 410 so that transmission and reception between the antenna module 320 and the RFID signal processing module 310 are performed in the same manner.

[33] In an embodiment, the modulator 420 converts a digital signal, input to the antenna module 320, into an analog signal. In general, a digital signal is a binary signal and, therefore, has its value not greatly distorted even with loss and noise during transmission. Further, some degree of loss or noise in the digital signal can be compensated for in a subsequent signal processing step. Thus, the digital signal is suitable for a long-distance communication, communication having many noise environments, communication requiring accuracy, and so on. The antenna module 320 of the present embodiment includes the modulator 420, and it can communicate analog signals with the tags and digital signals with the RFID signal processing module 310. Accordingly, signals can be transmitted or received accurately irrespective of the length of a transmission line. Further, although a plurality of antenna modules 320 is connected to the RFID signal processing module 310 through transmission lines having different lengths, accurate communication is possible irrespective of a difference in loss or noise during transmission. Therefore, according to the present embodiment, the reading sensitivity of the RFID reader system can be increased significantly and the degree of freedom in the configuration of a system can be

maximized.

[34] Meanwhile, the demodulator 430 can convert the analog signals, received from the antenna 410, into the digital signals again so that both transmission/reception between the antenna module 320 and the RFID signal processing module 310 is performed through the digital signals.

[35] The RFID signal processing module 310 includes a digital signal processor (DSP)

510 for processing the digital signals to/from the antenna module 320, and a CPU 520 for processing the signals to/from the DSP 510 suitably. The DSP 510 and the CPU 520 may employ a variety of known elements. Further, the CPU 520 may employ a commercial RFID module.

[36] FIG. 5 is a block diagram showing a detailed construction of the antenna module in accordance with an embodiment of the present invention.

[37] The antenna module 320 of the present embodiment includes the antenna 410, the modulator 420 and the demodulator 430, which are connected to a circulator 440. Thus, a signal from the modulator 420 is output to the antenna 410. The signal from the antenna 410 is input to the demodulator 430, but the flow of a signal from the demodulator 430 to the antenna 410 is cut off.

[38] The modulator 420 includes an operational amplifier (OP Amp) for receiving and amplifying a signal from the RFID signal processing module, a modulator for converting the amplified signal into a digital signal, a band pass filter (BPF) for filtering noise of the modulated signal, a drive amplifier and a power amp for amplifying the signal from the BPF so that it is suitable for transmission, and a BPF for filtering the amplified signal again in order to reduce noise.

[39] The demodulator 430 includes a BPF for filtering a received signal in order to reduce noise, a Balun for transforming a balance signal of the BPF into an unbalanced signal, a demodulator for demodulating the signal in order to convert an analog signal into a digital signal, and OP amps for amplifying the demodulated digital signal so that it is suitable for transmission to the signal processing module.

[40] Meanwhile, the modulator and the demodulator are supplied with clock signals, which are generated by a temperature compensated crystal oscillator (TCXO), a phased locked loop (PLL), and a voltage controlled oscillator (VC) and then divided by a divider. Thus, the modulator and the demodulator can perform analog-digital conversion on the basis of a common clock.

[41] FIG. 6 is a block diagram showing a RFID reader system in accordance with another embodiment of the present invention. In the present embodiment, the same reference numerals will be used to refer to the same parts as those of the previous embodiment and detailed description thereof is omitted.

[42] The RFID reader system of the present embodiment further includes a phase splitter

330 for allowing respective antenna modules 320, 322 and 324 to communicate with a signal processing module 310 using signals of different phases. The phase splitter 330 receives a signal from the signal processing module 310 and outputs a plurality of signals having different phases to the antenna modules 320, 322 and 324. Further, the phase splitter 330 receives a plurality of signals having different phases from the antenna modules 320, 322 and 324 and outputs one signal to the signal processing module 310.

[43] Therefore, respective antennas within the antenna modules 320, 322 and 324 are supplied with signals of different phases. Thus, beam patterns of the antennas become different from each other and therefore various beam patterns can be formed. Further, a variety of composite patterns can be formed by properly combining the patterns. In particular, as described above with reference to FIGS. 4 and 5, one or more antenna modules can be disposed freely without limits to the distance from RFID signal processing means by constructing the antenna module. Accordingly, a variety of beam patterns can be formed and the coverage of a system can be improved.

[44] Although the present invention has been described in connection with the concrete embodiments, they are only illustrative and the present invention is not limited to the embodiments. Those skilled in the art can change and modify the embodiments without departing from the scope and spirit of the invention. For example, it will be apparent to those skilled in the art that the constituent elements, shown as the blocks in the specification, can be implemented using various known elements such as an integrated circuit, ASIC, a programmable gate array (PGA), a logic programmable gate array (LPGA), a micro control unit (MCU) and an advanced RISC machine (ARM), commercialized modules or a combination of them. Therefore, the scope of the present invention is not limited to the embodiments as described above, and should be construed to be defined only by the appended claims and their equivalents.