WO2006078147A1

WO2006078147A1 - Thin rfid tag for radio frequency identification

Info

Publication number: WO2006078147A1
Application number: PCT/KR2006/000274
Authority: WO
Inventors: Jae Hyung Ryu
Original assignee: Rfcamp Ltd.
Priority date: 2005-01-24
Filing date: 2006-01-24
Publication date: 2006-07-27
Also published as: KR20060085452A

Abstract

A thin RFID tag capable of being attached to a conductor such as a metal and performing identification function, the thin RFID tag including: a first dielectric layer; a first antenna pattern formed in one area on a top of the first dielectric layer; a second antenna pattern formed in another area on a bottom of the first dielectric layer, the another area for the second antenna pattern formed in an area where only the another area is included in its vertical field; an RFID chip electrically connected to the first and second antenna pattern, respectively; a second dielectric layer formed below the second antenna pattern; and a ground pattern formed below the second dielectric layer to be electrically insulated from the first and second antenna patterns.

Description

THIN RFID TAG FOR RADIO FREQUENCY IDENTIFICATION

Technical Field

The present invention relates to a tag using Radio Frequency Identification 7 (RFID) technology, and more particularly, to an RFID tag stably operating on a product including a conductor such as metal.

Background Art

An RFID tag is generally formed of an IC chip and adhesive materials to H) communicate predetermined data with an external reader or interrogator and is called as a transponder.

The RFID tag communicates data with a reader in a noncontact method.

Depending upon an amplitude of a used frequency, inductive coupling, backscattering, or Surface Acoustic Wave (SAW) may be used. The RFID tag may communicate the

15 data with the reader by Full Duplex (FDX), Half Duplex (HDX), or sequential method by using electromagnetic waves.

As examples, the RFID tag is used for managing goods due to its noncontact nature and is used for variously IC cards for payment or a pass.

A low frequency range such as 135 KHz and 13.56 MHz may be utilized, but 0 Ultra High Frequency (UHF) range such as 900 MHz is currently used in distribution management. Particularly, in Wal-Mart, a big distribution enterprise, or the Pentagon, a frequency in the UHF range is generally used, and a passive tag passively operating according to an external change and generating required current without a built-in battery is once acknowledged as standards. 7> However, when a conductor exists around an RFID antenna, since transmission of electromagnetic waves is affected by the conductor, the antenna may not perform a stable antenna function. A basic structure of a dipole antenna generally needs to have a length of a half of λ (wavelength) and maintain a free space separated from a surface of an object by a distance of a quarter of λ in the least. However, even though a 0 frequency of 900 MHz, whose wavelength is relatively short, a quarter of λ is approximately 7 to 8 cm, which is relatively long.

Namely, for the RFID to normally operate on a surface of a conductor, the RFID has to be thick. Since an RFID tag has good utility and marketability due to having a thin size, this excellent advantage of the RFID tag may be not applicable using a conventional antenna structure.

.I Disclosure of Invention Technical Goals

An aspect of the present invention provides an RFID tag having an antenna structure capable of being used in a product composed of a metal and maintaining a thin size.

K) An aspect of the present invention also provides an RFID tag capable of being easily manufactured to be advantageous for mass production and being economic due to a low manufacturing cost.

Technical Solutions

1 r> According to an aspect of the present invention, there is provided a thin RFID including: a first dielectric layer; a first antenna pattern formed in one area on a top of the first dielectric layer; a second antenna pattern formed in another area on a bottom of the first dielectric layer, the another area for the second antenna pattern formed in a vertically exclusive area with respect to the one area in which the first antenna pattern is

20 formed: an RFID chip electrically connected to the first and second antenna pattern, respectively; a second dielectric layer formed below the second antenna pattern; and a ground pattern formed below the second dielectric layer to be electrically insulated from the first and second antenna patterns.

The first and second antenna patterns are each formed on a different surface on

27; the first dielectric layer and exclusively formed without vertically overlapped area, so that the second antenna pattern is formed in an area where only the second antenna pattern is included in its vertical field. Of course, in a real process of manufacturing and utilizing, an end portion of both patterns may become slightly overlapped or a lead line from any one of the patterns may become extended to form an overlapped area. M ' ) However, basically, the first and second patterns should not be vertically overlapped with each other. The end portions of both patterns may be formed to be close to each other to be approximately even with each other. The first and second antenna patterns are dipole antennas and may be formed to be a size of 0.25 λ , respectively. Also, the first and second antenna patterns are connected to each other via the RFID chip, thereby efficiently combining two dipole antenna functions and operating as one antenna. For example, the first antenna pattern 5 may receive a signal generated from a reader and may generate a current via a circuit, in response to the received radiofrequency signal. The second antenna pattern may communicate with the reader by using the current generated by the first antenna pattern, thereb) transferring and receiving information of each other.

The second dielectric layer and the ground pattern are disposed below the

H) second antenna pattern, thereby forming one RFID tag. The RFID tag manufactured as described above may be formed to have a thickness of approximately 0.8 mm or less and may be formed to have less thickness than a conventional art RFID tag while performing a normal RFID tag function.

I T) Brief Description of Drawings

FIG. 1 is a cross-sectional view of an RFID tag according to an embodiment of the present invention;

FlG. 2 is a perspective view of an RFID tag according to another embodiment of the present invention; 20 FIG. 3 is a top view of the RFID tag of FIG. 2;

FlG. 4 is an exploded perspective view of the RFID tag of FIG. 2; and FIG. 5 is a bottom perspective view illustrating a first dielectric layer and a second antenna part of FIG. 2.

27) Best Mode for Carrying Out the Invention

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the scope of the present invention is not defined or limited by the embodiments below.

FIG. 1 is a cross-sectional view of an RFID tag according to an embodiment of M ' the present invention.

Referring to FIG. 1, an RFID tag includes a first dielectric layer 1 10, a first antenna pattern 120, a second antenna pattern 130, an RFID chip 140, a second dielectric layer 150, and a ground pattern 160. The first and second dielectric layers 1 10 and 1 50 may be formed of an insulating material such as a resin film, may insulate the first antenna pattern 120 from the second antenna pattern 130, and may insulate the second antenna pattern 130 from the ground pattern 160. Also, the first and second ! patterns 120 and 130 and the ground pattern 160 are formed of a metal such as copper.

Particularly, the first antenna 120 and the second antenna 130 are formed on the top and the bottom of the first dielectric layer 1 10 and are provided in an vertically exclusive area to not be overlapped with each other.

Accordingly, as shown in FIG. 1, the first antenna pattern 120 is formed on a

K) left half portion of the top of the first dielectric layer 1 10 and the second antenna pattern 130 is formed on a right half portion of the bottom of the first dielectric layer 1 10.

Mutually adjacent end portions of the first antenna pattern 120 and the second antenna pattern 130 are formed to be approximately even with each other. Generally, the end portions of the first and second antennas 120 and 130 are not overlapped with

1.1 each other but may be formed to be separated or overlapped by a distance of approximately 0.1 to 0.5 mm.

The RFID chip 140 is provided between the first antenna pattern 120 and the second antenna pattern 130. Each of terminals of the RFID chip 140 may be connected to each of the first and second antenna patterns 120 and 130, respectively.

20 For example, the first antenna pattern 120 may receive a signal from a reader (not shown) and may generate a current via a circuit in response to the received radiofrequency signal, and the second antenna pattern 130 may communicate with the reader by using the current generated by the first antenna pattern 120 to transfer and receive information of each other.

2.1 The second dielectric layer 150 is provided below the second antenna pattern

130, and the ground pattern 160 is provided below the second dielectric layer 150. The ground pattern 160 is generally attached to a surface of a conductor and may assist the first and second antenna patterns 120 and 130 in normally communicating utilizing an electromagnetic wave signal.

30 FIG. 2 is a perspective view of an RFID tag according to another embodiment of the present invention, FIG. 3 is a top view of the RFID tag of FIG. 2, and FIG. 4 is an exploded perspective view of the RFID tag of FIG. 2. Referring to FIGS. 2 through 4, an RFID tag 200 according to the present embodiment includes a first antenna part including a first dielectric layer 210 and a first antenna pattern 220, a second antenna part including a second antenna pattern 230, an RFID chip 240, a second dielectric layer 250, and a ground pattern 260. The first and ,1 second dielectric layers 210 and 250 may be formed of an insulating material such as a resin film, may insulate the first antenna pattern 220 from the second antenna pattern 230. and may insulate the second antenna pattern 230 from the ground pattern 260. Also, the first antenna pattern 220, the second antenna pattern 230, and the ground pattern 260 are formed of a metal such as copper.

K) The first antenna part includes the first antenna pattern 220 formed in a rectangular shape whose width is approximately 7 to 8 cm and length is approximately 3 cm. The first antenna pattern 220 is formed on the first dielectric layer 210.

In response to the first antenna part, the second antenna part is formed on the bottom of the first dielectric layer 210 and includes the second antenna pattern 230, a 1 .1 lead unit 232, and a connection terminal unit 234.

The second antenna pattern 230 is also formed in the same size of the first antenna pattern 210 and formed in a rectangular shape. The first antenna pattern 220 and the second antenna pattern 230 are formed on the top and the bottom of the first dielectric layer 210 and formed in an verticallyexclusive area to not be overlapped with 0 each other. Mutually adjacent end portions of the first antenna pattern 220 and the second antenna pattern 230 are formed close to each other to be approximately even with each other.

Generally, the end portions of the first and second antenna patterns 220 and 230 are not overlapped with each other, but may become formed to be separated or 1 overlapped by a distance of approximately 0.1 to 0.5 mm.

Also, the lead unit 232 formed in the shape of a letter L is formed from the end portion of the second antenna pattern 230, and the connection terminal unit 234 is formed at an end of the lead unit 232. The connection terminal unit 234 is formed to be separated from the lead unit 232 at a predetermined interval. Also, the connection 0 terminal unit 234 is electrically connected to the first antenna pattern 220. To electrically connect the connection terminal unit 234 with the first antenna pattern 220, a hole ( not shown) penetrating the first dielectric layer 210 and the connection terminal unit 234 is formed and the first antenna pattern 220 is electrically connected to the connection terminal unit 234 via the hole. There may be formed one hole or a plurality of holes. The hole is filled with an electric conductor or conductors between the first antenna pattern 220 and the connection terminal unit 234, thereby mutually connecting T> the first antenna pattern 220 with the connection terminal unit 234.

FlG. 5 is a bottom perspective view illustrating a first dielectric layer and a second antenna part of FIG. 2.

Referring to FIG. 5, the RFID chip 240 is provided between the lead unit 232 and the connection terminal unit 234 and terminals of the RFID chip 240 may be

U) connected to the first antenna pattern 220 and the second antenna pattern 230, respecth ely. An area in which the RFID chip 240 is formed may be protected by a coating using a resin such as epoxy.

The second dielectric layer 250 is provided below the second antenna pattern

230, and the ground pattern 260 is provided below the second dielectric layer 250.

1 T) Since the ground pattern 260 is generally attached to be adjacent to a surface of a conductor, the ground pattern 260 may assist the first and second antenna patterns 220 and 230 in normally communicating an electromagnetic wave signal.

Industrial Applicability 20 The RFID tag of the present invention may be used in a product formed of metals, such as a vehicle, an engine of a vehicle, a refrigerator, and a main body of a computer and may have a thickness of approximately 0.8 mm or less, thereby improving applicability and marketability.

Also, since manufacturing is easy, the RFID tag is advantageous to mass 2T) production, and, since a manufacturing cost is low, applying the RFID technology to pruducts is very economic.

Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these A ^' O embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A thin RFID tag comprising: a first dielectric layer; a first antenna pattern formed in one area on a top of the first dielectric layer; 7 a second antenna pattern formed in another area on a bottom of the first dielectric layer, the another area for the second antenna pattern formed in an area where only the another area is included in its vertical field; an RFID chip electrically connected to the first and second antenna pattern, respectively; 10 a second dielectric layer formed below the second antenna pattern; and a ground pattern formed below the second dielectric layer to be electrically insulated from the first and second antenna patterns.

2. The thin RFID tag of claim 1, wherein the first antenna pattern is formed in a I T) rectangular shape on the top of the first dielectric layer, the second antenna pattern is formed in a rectangular shape whose size is approximately the same size as the first antenna pattern, and the first and second antenna patterns are disposed to be parallel to each other and vertically exclusive from each other.

20 3. A thin RFID tag comprising: a first dielectric layer; a first antenna part comprising a first antenna pattern formed in one area on the first dielectric layer; a second antenna part comprising a second antenna pattern formed below the 27) first dielectric layer to not be overlapped with the one area in which the first antenna pattern is formed, a lead unit electrically connected to the second antenna pattern and extended below the one area in which the first antenna pattern is formed, and a connection terminal unit formed to be adjacent to an end of the lead unit and electrically connected to the first antenna pattern; A ' O an RFID chip installed between the lead unit and the connection terminal unit and electrically connected to the lead unit and the connection terminal unit respectively; a second dielectric layer formed below the second antenna part; and a ground pattern formed below the second dielectric layer and electrically insulated from the first and second antenna parts.

4. The thin RFID tag of claim 3, wherein a hole penetrating the first antenna pattern, the first dielectric layer, and the connection terminal unit is formed and the first antenna pattern is electrically connected to the connection terminal unit via the hole.