JP2004086683A - Rf tag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to transmit/receive data from/in the whole directions of an RF tag. <P>SOLUTION: A first antenna 13-1 and a second antenna 13-2 of a pair of dipole antenna 13 connected to an IC chip 12 arranged on a substrate 11 are formed like an approximate L shape rectangular to the IC chip 12. Even when a radio wave which is transmitted from the longitudinal horizontal surface of either one of the 1st and 2nd antennas 13-1, 13-2 but can not be caught arrives, the direction of the other antenna is turned to a longitudinal vertical surface to the radio wave, so that radio waves from all directions can be completely caught. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an RF tag that transmits and receives data without contact using radio waves from a reader / writer (hereinafter, referred to as R / W).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a data carrier system using an R / W and an RF tag is known as a system for reading and writing various data related to an article such as a product or luggage and performing identification management of the article. This RF tag is characterized in that various data can be transmitted and recorded in a non-contact manner by radio communication from the R / W.
[0003]
This type of RF tag generally has a data transmission method between R / W,
◎ Electrostatic coupling method (using electrostatic induction by static electricity)
◎ Electromagnetic induction method (one that uses electromagnetic induction action by induction electromagnetic field)
◎ Microwave method (one that uses microwave band radio waves generated by a radiated electromagnetic field)
◎ Optical communication system (using infrared or other light)
Among them, the electromagnetic induction type and the microwave type are mainly used.
[0004]
FIGS. 5 and 6 show examples of the configuration of these RF tags. FIG. 5A is a plan view showing the configuration of the tag, and FIG. FIG. 3 is a directional characteristic diagram showing an area.
[0005]
First, FIG. 5 shows an electromagnetic induction type RF tag. This tag is provided with an IC chip 2 having a built-in communication circuit and a memory on a substrate 1, and a loop antenna 3-1 printed with silver paste or the like is connected to the IC chip 2. On the other hand, a loop antenna 4-1 is similarly formed on the R / W side. When a signal having a frequency of several hundred KHz to several MHz is applied to the loop antenna 3-1 of the tag, a current is induced in each of the loop antennas 3-1 and 4-1 by electromagnetic induction, and the tag and the R / W are connected to each other. Data can be transmitted and received between them.
[0006]
Next, a microwave RF tag is shown in FIG. In this tag, an IC chip 2 is similarly provided on a substrate 1, and a pair of dipole antennas 3-2 extending on the same straight line are connected to both sides of the IC chip 2. On the other hand, a dipole antenna 4-2 is similarly formed on the R / W side. When a radio wave of a frequency of 2.45 GHz (microwave band) is supplied to the dipole antenna 3-2 of the tag, data can be transmitted and received between the tag and the R / W.
[0007]
However, these conventional RF tags have the following problems.
[0008]
First, in the case of the tag using the electromagnetic induction method of FIG. 5, as shown in FIG. 5B, the communicable area E5 of this tag is usually about several tens of cm as a distance between the tag and the R / W. When viewed from the direction of arrow A, the antenna has directivity close to the figure of 8 in the direction of the normal to the loop antenna 3-1. On the other hand, the communicable range is narrow.
[0009]
In the case of the tag of the microwave system shown in FIG. 6, the communicable area E6 of this tag is relatively 1 to 4 m as a distance from the R / W, as shown in FIG. Extensive. However, when viewed from the direction of arrow A, like the electromagnetic induction type tag of FIG. 5, it has directivity closer to the figure 8 in the normal direction of the dipole antenna 3-2. The communicable range is narrow for radio waves from the horizontal direction (arrows B and C).
[0010]
As described above, regardless of the tag of any transmission method, it is possible to communicate with radio waves in the horizontal direction of the antenna indicated by the arrows (b) and (c) in the figure, that is, in the direction perpendicular to the thickness of the tag. Since the range is narrow, communication may not be possible depending on the distance from the R / W or weak radio waves, and transmission / reception of various data to / from the tag by the R / W may be influenced by the reading direction of the tag.
[0011]
Therefore, for example, when a product with a tag is packed in a cardboard box and the tag data is read without opening the box, or when batch reading without changing the direction of the tagged product in a shopping cart In some cases, tags cannot be read with one R / W.
[0012]
Further, in order to compensate for such a drawback of the RF tag, there has been proposed a method of installing an R / W antenna in two horizontal and vertical directions with respect to the tag. , R / W antennas must be prepared, resulting in an increase in the size of the entire data carrier system and a significant increase in cost.
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of such a problem, and an object of the present invention is to increase the overall size and cost of the system without affecting the tag reading direction from all directions. An object of the present invention is to provide an RF tag that enables transmission and reception of the RF tag.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, an RF tag according to the present invention includes a substrate formed of an insulator, a communication circuit provided on the substrate, for transmitting and receiving various data to and from an external reader / writer, and a memory for storing various data. And a linear first antenna made of a conductor connected to the IC chip, and a linear antenna made of a conductor connected to the IC chip on a non-colinear line with the first antenna. And a second antenna. In particular, if the first antenna and the second antenna are arranged on perpendicular lines orthogonal to each other, even if an unacceptable radio wave arrives from the longitudinal horizontal plane of one of the antennas, the direction of the other antenna will be longer. It becomes a plane perpendicular to the direction, and this radio wave can be reliably picked up.
[0015]
There are various methods for forming the first antenna and the second antenna. For example, a conductive film is formed on a substrate by a pattern printing method using a silver paste or a copper plate is etched on a substrate.
[0016]
Further, if an adhesive layer is provided on the back surface of the substrate, this RF tag can be conveniently attached to an article such as a product or luggage.
[0017]
According to the RF tag according to the present invention, in particular, the radio wave from the external R / W can always be captured by any one of a pair of antennas orthogonal to each other. And there is no influence of the reading angle between them, and data can be transmitted and received from all directions.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of an RF tag according to the present invention will be described in detail with reference to the accompanying drawings.
[0019]
1 is a plan view showing the configuration of the RF tag according to the present invention, FIG. 2 is a cross-sectional view showing the configuration of the RF tag, FIG. 3 is a directional characteristic diagram showing a readable area of the RF tag, and FIG. It is a perspective view showing an example which applied a tag to a price tag.
[0020]
As shown in FIGS. 1 and 2, the RF tag 10 includes a substrate 11 made of an insulator such as various synthetic resins formed into a flat plate, an IC chip 12 provided on the substrate 11, and an IC chip 12. This is a microwave RF tag including a pair of dipole antennas 13 (13-1, 13-2) that are electrically connected. When a radio wave of a frequency of 2.45 GHz (microwave band) is supplied from the R / W side (not shown) to the dipole antenna 13 of the RF tag 10, transmission and reception of various data between the R / W and the RF tag 10 are performed. It becomes possible.
[0021]
As the IC chip 12, a thin chip having a built-in communication circuit for transmitting and receiving various data to and from an external R / W and a memory for storing the various data can be used. By using a flash memory, a tag without a battery can be obtained.
[0022]
The dipole antenna 13 is made of a conductive material. For example, the dipole antenna 13 is formed on the substrate 11 by a method of pattern printing with a silver paste on an inlet base made of paper or polyimide, or a method of etching a metal plate such as a copper plate. Is formed with a conductive film.
[0023]
Further, the dipole antenna 13 is characterized in that it has a shape capable of capturing radio waves from R / W regardless of the direction of the RF tag 10, and the linear first antenna 13- 1 and the second linear antenna 13-2 need to be arranged at least at positions that are not on the same straight line with each other (preferably at a position where the angle between them is 45 to 135 degrees).
[0024]
In the present embodiment, as shown in FIG. 1, the first antenna 13-1 is connected to the IC chip 12 so as to be parallel to the length direction of the substrate 11, and the second antenna 13-2 is It is connected to the IC chip 12 so as to be parallel to the width direction. That is, as a whole, the dipole antenna 13 is formed on the substrate 11 such that the first antenna 13-1 and the second antenna 13-2 are substantially L-shaped with respect to the IC chip 12 on vertical lines perpendicular to each other. Have been.
[0025]
In order to strictly protect the interior components including the IC chip 12 and the dipole antenna 13 constituting the RF tag 10 from the external environment such as moisture and heat, these surfaces are made of synthetic resin having water resistance and heat resistance. May be molded to provide the exterior package 14. Although not shown, providing an adhesive layer on the back surface of the substrate 11 is convenient because the RF tag 10 can be attached to an article such as a product or luggage.
[0026]
Next, the directional characteristics of the RF tag thus configured will be described with reference to FIG.
[0027]
As described above, the RF tag 10 has the first antenna 13-1 and the second antenna 13-1 formed by forming the dipole antenna 13 on the flat substrate 11 in an L shape orthogonal to the IC chip 12. The antenna 13-2 is orthogonal to each other. Therefore, even if a radio wave that cannot be captured from the longitudinal horizontal plane of one of the first antenna 13-1 and the second antenna 13-2 arrives, the direction of the other antenna is perpendicular to this radio wave in the longitudinal direction. As a result, this radio wave can be reliably picked up.
[0028]
That is, as shown in FIG. 3, the RF tag 10 is placed on an XY plane including an X axis and a Y axis orthogonal to each other, and a plane defined by a Z axis perpendicular to the XY plane is set. Assuming X-Z plane and Y-Z plane, respectively, X1, Y2 radio waves, Y1, Y2 radio waves, These are called Z1 and Z2 radio waves.
[0029]
At this time, first, since the X1 radio wave and the X2 radio wave are both radio waves from the longitudinal horizontal plane of the first antenna 13-1, they cannot be captured by the first antenna 13-1, but the second antenna 13-2 , The X1 radio wave and the X2 radio wave can both be captured by the second antenna 13-2.
[0030]
Next, since both the Y1 radio wave and the Y2 radio wave are radio waves from the horizontal plane in the longitudinal direction of the second antenna 13-2, the Y1 radio wave and the Y2 radio wave cannot be captured by the second antenna 13-2. Since the radio waves are from the vertical plane, both the Y1 radio wave and the Y2 radio wave can be captured by the first antenna 13-1.
[0031]
Further, since the Z1 radio wave and the Z2 radio wave are both radio waves from the vertical plane with respect to both the first antenna 13-1 and the second antenna 13-2, the first antenna 13-1 and the second antenna 13 -2 can be captured.
[0032]
As described above, even if a radio wave that cannot be captured from the longitudinal horizontal plane of one of the first antenna 13-1 and the second antenna 13-2 arrives, the dipole antenna 13 of this RF tag 10 Since the antenna is arranged at a position perpendicular to the longitudinal direction with respect to this radio wave, radio waves from all directions can be picked up without leakage.
[0033]
Therefore, as shown in FIG. 4, for example, even when the product 30 with the RF tag 10 is packed in the cardboard box 40 in an arbitrary direction, the cardboard box 40 is opened and the direction of the product 30 is not changed. Even one R / W 20 can read and write the data of the RF tag 10.
[0034]
That is, in this embodiment, the RF tag 10 is used as a price tag, the price of the product 30 is printed on the surface of the RF tag 10, and the price data and other data related to the product 30, such as a product item name and a product number. , A serial number, a manufacturer name and the like are stored in a memory built in the IC chip 12. On the other hand, when the cardboard box 40 accommodating a plurality of products 30, 30,... Passes through the R / W 20, it is assumed that the RF tags 10 attached to the products 30 face various directions.
[0035]
However, no matter what direction the RF tag 10 faces in the cardboard box 40, the radio wave from the R / W 20 is transmitted to the first antenna 13-1 or the second antenna 13 of the RF tag 10 as shown in FIG. -2 can be captured. For this reason, there is no need to open the cardboard box 40 to take out the individual products 30 or change the direction of the cardboard box 40. One R / W 20 collectively reads and writes necessary data on all the products 30. It can be performed reliably without leakage.
[0036]
【The invention's effect】
As described above in detail, according to the RF tag of the present invention, at least one of a pair of orthogonal antennas can capture radio waves from an external R / W without leakage. Therefore, the influence of the reading angle between the external R / W antenna and the RF tag is eliminated, and data can be transmitted and received from all directions. Therefore, for example, when a product with this RF tag is packed in a cardboard box and the data of the RF tag is read without opening the box, or without changing the direction of the product with the RF tag placed in a shopping cart, Also in the case of reading, reading and writing can be performed with one fixed R / W, and the convenience of the RF tag can be greatly improved without increasing the size and cost of the entire system.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an RF tag according to the present invention.
FIG. 2 is a sectional view taken along line II-II shown in FIG.
FIG. 3 is a directional characteristic diagram showing a readable area of the RF tag according to the present invention.
FIG. 4 is a perspective view showing an embodiment in which the RF tag according to the present invention is applied to a price tag.
5A is a plan view illustrating a configuration of a conventional electromagnetic induction type RF tag, and FIG. 5B is a directional characteristic diagram illustrating a communicable area as viewed from a direction A.
6A is a plan view showing a configuration of a conventional microwave RF tag, and FIG. 6B is a directional characteristic diagram showing a communicable area viewed from a direction A.
[Explanation of symbols]
Reference Signs List 10 RF tag 11 Substrate 12 IC chip 13 Dipole antenna 13-1 First antenna 13-2 Second antenna 14 Outer package 20 Reader / writer (R / W)
30 products 40 cardboard boxes

Claims (5)

A substrate made of an insulator;
An IC chip provided on the substrate and having a built-in communication circuit for transmitting and receiving various data to and from an external reader / writer and a memory for storing various data;
A first linear antenna made of a conductor connected to the IC chip;
An RF tag, comprising: a second linear antenna made of a conductor connected to an IC chip on a non-colinear line with the first antenna. The RF tag according to claim 1, wherein the first antenna and the second antenna are arranged on vertical lines orthogonal to each other. 3. The RF tag according to claim 1, wherein the first antenna and the second antenna are formed by pattern-printing a silver paste on a substrate. 3. The RF tag according to claim 1, wherein the first antenna and the second antenna are formed by etching a copper plate on a substrate. The RF tag according to claim 1, wherein an adhesive layer is provided on a back surface of the substrate.

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