This application is a National Stage Patent Application of PCT International Patent Application No. PCT/KR2012/004200 (filed on May 29, 2012) under 35 U.S.C. § 371, which claims priority to Korean Patent Application Nos. 10-2011-0056486 (filed on Jun. 10, 2011), 10-2011-0106158 (filed on Oct. 18, 2011), 10-2011-0123833 (filed on Nov. 24, 2011) and 10-2012-0055483 (filed on May 24, 2012), the teachings of which are incorporated herein in their entireties by reference.
The present invention relates, in general, to printed circuit board (PCB) tracking technology and, more particularly, to a dipole antenna structure for radio frequency identification (RFID) tags. Yet more particularly, the present invention relates to an edge type antenna structure which can be provided with a very small size in an edge portion of a ground plane of a PCB for a variety of electronic products, a PCB including the same, and an electronic product management system including the same.
Electronic products, for example, TVs, mobile phones, computers, portable music players and the like, include at least one printed circuit board (PCB). PCBs for electronic products undergo part assembly and inspection processes for electronic products in a preset fabrication line.
Barcode labels were used as an approach for managing the process of assembling electronic product PCBs (including the inspection process) of the related art. For instance, this method manages all processes including the assembly process by identifying barcodes printed on a barcode label using a scanner and updating the identified barcodes in a management server when one process is completed in the production line.
Describing the foregoing management method using barcode labels, there are restrictions in that the miniaturization of labels is limited, and that labels must be attached to positions where they can be exposed at any time to a scanner. In addition, scanning and processing time that reaches up to several tens of seconds can cause a time delay in the assembly process. If an electronic product PCB is small, trouble occurs in that the barcode label must be detached for the purpose of the parts assembly process and then reattached when the corresponding process is finished. Therefore, the subsequent process is delayed. For reference, the amount of processing time that is uselessly spent can be estimated considering the number of assembly steps and that the processes of attaching and detaching barcode labels are manually performed.
In order to overcome the problem of the barcode system, several electronic product manufacturers introduced radio frequency identification (RFID) tags. As is known, RFID tags are divided into active tags and passive tags depending on the presence of operating power. The active tag has limitations to miniaturization since it must include a power source (e.g. a battery). Accordingly, the passive tag which uses a radio wave radiated from an antenna of an RFID tag reader is widely used.
The passive tag basically includes a tag chip and an antenna. There are two methods of applying the passive tag to the above-mentioned electronic product PCB. One is to attach the RFID tag to the PCB like the barcode label, and the other one is to mount a passive tag on the electronic product PCB. The latter requires the electronic product PCB to be provided with an antenna pattern which is to be connected to the tag chip. This means a space on the PCB corresponding to the size of the antenna is required. It is difficult, however, to provide an antenna pattern space for the tag chip in a PCB of a small electronic product, for example, a portable phone.
As a related art for overcoming this problem, disclosed was United States Patent Application Publication No. US2010/0219941 “SYSTEM, APPARATUS, AND METHOD FOR PCB-BASED AUTOMATION TRACEABILITY” (hereinafter referred to as “'941 patent”). The '941 patent is significant in that a ground plane of a PCB is used as an antenna for a tag. Specifically, the antenna in '941 patent has a structure known as a “slot antenna.” As apparent from the figures in '941 patent, a slot formed at a preset length on the ground plane acts as an antenna. However, the length of the slot is required to be about 70 mm when an intended frequency is 900 MHz and an entire frequency wavelength is used and about 35 mm even if half a frequency wavelength is used.
However, considering the trends of PCBs toward small size and high integration that are becoming more demanding every day, the length of the slot has a significant effect on design conditions such as formation of traces (or signal patterns) or arrangement of components. For instance, the slot causes some traces to be designed to take a roundabout path instead of an optimum path. This has an effect over not only that trace but also arrangement of the other traces and components.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an antenna structure, the size of which is reduced compared to that of the related art.
In order to accomplish the above objects, the present invention provides an edge type dipole antenna structure.
As disclosed in claim 1 of this application, the edge type dipole antenna structure basically includes a slit having a minute length, the slit forming a gap in an edge of a ground plane provided in a PCB; and an expanded portion extending from the slit, the expanded portion imparting inductive reactance to the slit. The optimal shape of the expanded portion may be a circle like a typical coil. A passive RFID tag chip is connected to the slit, and according to an aspect of the invention, the edge of the ground plane acts as a dipole antenna of the tag chip.
According to the present invention, the edge of the ground plane provided in the PCB of an electronic product can be used as the dipole antenna for the tag chip. Therefore, unlike the related art, a space on the PCB for an antenna dedicated to the tag chip is not required.
In addition, the edge type antenna structure disclosed herein can be embodied in a small size.
Furthermore, the PCB in which the edge type dipole antenna structure according to the invention is provided can have wide and various applications, for example, a system which manages the assembly process for electronic products and performs follow-up management such as repair or warranty service (A/S).
The specific features and advantages of the invention will be more apparent from the following description taken in conjunction with the accompanying drawings. Before that, it should be understood that detailed descriptions of known functions and components incorporated herein will be omitted when they may make the subject matter of the present invention unclear. In addition, unless explicitly stated to the contrary, the word “comprise (comprises or comprising)” will be understood that the exclusion of any other elements is not implied and further components can also be included.
Reference will now be made in detail to a PCB including an edge type dipole antenna according to a first embodiment.
A printed circuit board (PCB) referred to herein is the term of a PCB on at least one surface of which a ground plane is formed and includes a flexible PCB. The PCB 100 according to the first embodiment will be described by simplifying it as including a ground plane 110A provided on one surface, as shown in
Referring to
A tag chip 10 is connected to the ground plan 110A, at the gap or across the slit 120. The length “ds” of the slit 120 can have a minimum size such that the tag chip 10 can be connected, for example, the one-direction length of the tag chip 10. Reference numerals P1 and P2 designate pads with which the tag chip 10 is connected to the ground plane 110A through surface mounting.
Here, referring to
Specifically, referring to
The current that flows along the expanded portion 130 generates a magnetic field through the expanded portion 130, and resultant inductive reactance is loaded to the slit 120. Consequently, a common mode voltage is generated at the edge 111 of the ground plane 110A, first from the slit 120. According to features of the invention, the edge 110 acts as “a dipole antenna” of the tag chip 10.
According to one feature of the invention, an inductive reactance value is controlled by the expanded portion 130, and power for activating the tag chip 10 (that can also be understood as “power to be absorbed by the tag chip”) can be adjusted. When the expanded portion 130 is circular, the inductive reactance value is controlled due to adjustment in the radius “b.” A detailed description will be given below of a specific method of designing the inductive reactance value.
In addition, considering that the expanded portion 130 generates inductive reactance, the optimal shape of the expanded portion 130 is “circular” like a typical coil. However, the expanded portion 130 of the present invention is not limited to the circular shape and can, of course, be modified into shapes other than a circle. For instance, the expanded portion of the present invention can be modified into an oblong shape illustrated in
As shown in
A description will be given below of a PCB according to a second embodiment of the invention. As described above, the PCB according to the second embodiment has ground planes formed on both surfaces thereof. Herein, for the purpose of discriminating the terms, the ground plane formed on the upper surface of the PCB 100 will be referred to as “the upper-surface ground plane,” and the ground plane formed on the undersurface of the PCB 100 will be referred as “the undersurface ground plane.” In addition, as for reference numerals for components, the reference numerals of the first embodiment will be used.
Referring to
This removed portion 112B is intended to allow a magnetic field generated in the expanded portion 130 to easily pass through the PCB 100, whereby inductive reactance is more efficiently generated. This function of the removed portion 112B basically corresponds to the function of the through-hole 132 illustrated in the first embodiment. Therefore, the area of the removed portion 112B is required to surround at least the expanded portion 130 formed in the upper-surface ground plane 110A. In addition, the removed portion 112B may be smaller or greater than or the same as the area of the expanded portion 130. In addition, the removed portion may be modified so as to surround the entire slit 120 including the expanded portion 130, as shown in
The entire size of the slit 120 and the expanded portion 130 which are components of the edge type dipole antenna structure according to the invention can be modified so as to be smaller than that of the first embodiment and that of the second embodiment. Several modified embodiments will be examined with reference to
A description will be given below of designing of inductive reactance using the expanded portion according to the invention.
When XL determined by Formula 1 is loaded on the slit 120, maximum power is received in the tag chip 10 provided on the slit 120.
In addition, the expanded portion 130 according to the invention can be designed to be circular, as shown in
where “a” refers to the thickness of the ground plane, f refers to the frequency of the reader-writer, and μ refers to the permeability of a dielectric substance. The permeability value is close to 1.
In addition, when the expanded portion 130 is oblong, as shown in
A description will be given below of the results of several simulations that are executed. The impedance Zc of the tag chip is 25−j45Ω.
As such, it is possible to design the lengths of the sides h1 and h2 at which the tag chip 10 can receive the maximum amount of power when the expanded portion 130 is not circular and is oblong as shown in
The inventor carried out an experiment based on the edge type dipole structure shown in
The PCB 100 including the foregoing edge type dipole antenna structure can be applied to a system which manages the assembly process for electronic products and performs follow-up management such as repair or warranty service (A/S). More specifically, in
As shown in
The reader-writer 200 can read out information from the tag chip 10 or record information in the tag chip 10 via radio communication at a frequency of 900 MHz. Information recorded in or read out from the tag chip 10 can include identification information of electronic products and varies pieces of information necessary for process management.
The reader-writer 200 can be connected to a user computer 300 through a wired/wireless network, as shown in
The foregoing descriptions have been presented for the purposes of illustration of the technical principle of the present invention. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are apparent to a person having ordinary skill in the art. Therefore, such all suitable modifications, corrections and equivalents shall be understood to fall within the scope of the invention.
As set forth above, the edge type dipole antenna structure disclosed herein can be embodied as a small structure in a PCB of an electronic product and be widely used for process management over the PCB and follow-up management such as repair or warranty service.
Number | Date | Country | Kind |
---|---|---|---|
10-2011-0056486 | Jun 2011 | KR | national |
10-2011-0106158 | Oct 2011 | KR | national |
10-2011-0123833 | Nov 2011 | KR | national |
10-2012-0055483 | May 2012 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/KR2012/004200 | 5/29/2012 | WO | 00 | 10/21/2013 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2012/169738 | 12/13/2012 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
20030181229 | Forster | Sep 2003 | A1 |
20040008146 | Ikegaya | Jan 2004 | A1 |
20050275539 | Sakama et al. | Dec 2005 | A1 |
20060001138 | Sakama et al. | Jan 2006 | A1 |
20080036673 | Yamagajo et al. | Feb 2008 | A1 |
20080252425 | Okegawa et al. | Oct 2008 | A1 |
20090021379 | Zhu | Jan 2009 | A1 |
20090058658 | Kai et al. | Mar 2009 | A1 |
20100219941 | Pagano et al. | Sep 2010 | A1 |
20100308118 | Kataya et al. | Dec 2010 | A1 |
20110134622 | Yu et al. | Jun 2011 | A1 |
20110284643 | Yamagajo et al. | Nov 2011 | A1 |
20130027268 | Ohno | Jan 2013 | A1 |
20130315511 | Chen | Nov 2013 | A1 |
Number | Date | Country |
---|---|---|
101159035 | Apr 2008 | CN |
101707887 | May 2010 | CN |
101814157 | Aug 2010 | CN |
101953025 | Jan 2011 | CN |
2006-018421 | Jan 2006 | JP |
2008-148122 | Jun 2008 | JP |
2011-059969 | Mar 2011 | JP |
10-0705359 | Apr 2007 | KR |
Entry |
---|
Pjbevel, Cavity-Backed Slot Antennas, Feb. 2, 2009, https://web.archive.org/web/20090202040802/http://www.antenna-theory.com/antennas/aperture/slot2.php. |
European Patent Office, Supplementary European Search Report of EP Application No. 12 79 6037, dated Nov. 14, 2014. |
Number | Date | Country | |
---|---|---|---|
20140042226 A1 | Feb 2014 | US |