JP2013114513A - Information storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information storage medium capable of coping with a plurality of frequencies for communication without changing a sticking position of a radio IC tag.SOLUTION: An information storage medium 1 includes a radio communication improvement sheet body 10 and a radio IC tag 20. The radio communication improvement sheet body 10 includes a first spacer 2, an auxiliary antenna 3, a second spacer 4 and a rear face conductor layer 5. The auxiliary antenna 3 is stuck to the second spacer 4 by a first adhesive 3a and the rear face conductor layer 5 is stuck to the second spacer 4 by a second adhesive 5a. A hole S is provided in the auxiliary antenna 3 so that a width W of the hole S is longer than lengths of long side portions 23a and 23b of a loop antenna 21a.

Description

  The present invention relates to an information storage medium using a wireless IC tag.

  Wireless communication technology is applied not only in the field of information communication but also in fields such as logistics management, and an IC tag for wireless communication (hereinafter simply referred to as “wireless IC tag”) is a part of RFID (Radio Frequency Identification) technology. It is widely known as a product that bears

  Wireless IC tags are classified into a passive type that does not have its own power source and an active type that has a power source. A low-cost and versatile passive type receives radio waves from a reader, activates an IC circuit using this energy, and enables wireless communication.

  The wireless IC tag is composed of an IC chip that stores data such as identification information and an antenna for transmitting and receiving radio waves, and has a great advantage that wireless communication can be realized with a thin shape and light weight. Since the IC chip is provided with a memory area, information management is possible using various kinds of information stored therein.

  Taking advantage of the thin and light weight, the wireless IC tag can be used as physical distribution management or an inexpensive information storage medium. However, since the usage is diverse, it is placed in various usage environments.

  For example, if a wireless IC tag is attached to a metal material and used, the communication characteristics of the antenna deteriorate, and the communicable distance is shortened. When pasting on a metal material and using it, for example, a wireless communication improving sheet as disclosed in Patent Document 1 may be used.

  Also, in the case of UHF band wireless IC tags, communication frequencies are allocated differently by country, such as 902 to 928 MHz in the United States, 952 to 954 MHz in Japan, 910 to 915 MHz in South Korea, and 866 to 868 MHz in the EU. . In the wireless communication improvement sheet body described in Patent Document 1, when the attachment position of the wireless IC tag is changed with respect to an adjustment unit for adjusting a resonance frequency such as a hole or a notch provided in the auxiliary antenna, It can correspond to the frequency for communication.

International Publication No. 2010/38813

When the wireless communication improving sheet described in Patent Document 1 is used, it is necessary to change the position of the wireless IC tag every time the communication frequency is different. For example, a wireless IC tag attaching position is determined in advance for each country to be used, and the wireless IC tag is attached to the position determined at the time of product shipment. If the pasting position is shifted or the corresponding frequency is pasted incorrectly, wireless communication cannot be performed. When reusing the wireless communication improvement sheet body and trying to use a wireless IC tag with a different communication frequency, it is necessary to peel off the pasted one and paste it again at a predetermined position. .

  An object of the present invention is to provide an information storage medium capable of supporting a plurality of communication frequencies without changing the attachment position of the wireless IC tag.

The present invention includes a rectangular loop antenna, and a wireless IC tag including an integrated circuit element connected to the loop antenna and storing identification information;
A first spacer having an arrangement surface on which the wireless IC tag is arranged;
An auxiliary antenna provided on a surface of the first spacer opposite to the arrangement surface, the inner dimension of the long side of the loop antenna at a position corresponding to the loop antenna across the first spacer An auxiliary antenna comprising a conductor layer provided with a hole having a width equal to or greater than the length;
An information storage medium comprising: a second spacer provided on a side opposite to the first spacer with the auxiliary antenna interposed therebetween.

In the present invention, the integrated circuit element is connected to one long side of the loop antenna,
The loop antenna is provided so that the one long side is located in the hole and the other long side overlaps the conductor layer when viewed from the stacking direction.

  Further, the present invention is characterized in that the wireless IC tag complies with the EPC Class 1 Generation 2 standard, and the communication frequency band is the UHF band.

  According to the present invention, a rectangular loop antenna and a wireless IC tag made of an integrated circuit element connected to the loop antenna and storing identification information are used. The auxiliary antenna has an inner length of the long side of the loop antenna. It consists of a conductor layer provided with holes having a width of more than that.

  Accordingly, the communication frequency can be widened without changing the position where the wireless IC tag is attached, and a plurality of communication frequencies can be handled.

According to the invention, the loop antenna is provided so that the one long side is positioned in the hole and the other long side overlaps the conductor layer when viewed from the stacking direction.
As a result, the communication frequency can be made wider.

  According to the present invention, it is preferable that the wireless IC tag conforms to the EPC Class 1 Generation 2 standard and the communication frequency band is the UHF band.

It is sectional drawing which shows the structure of the information storage medium 100 which is embodiment of this invention. 2 is a plan view of the information storage medium 1. FIG. 3 is a graph showing frequency characteristics of communication distance in Example 1. 6 is a graph showing frequency characteristics of communication distance in Example 2. It is a graph which shows the frequency characteristic of the communication distance of a comparative example.

  FIG. 1 is a cross-sectional view showing a configuration of an information storage medium 1 according to an embodiment of the present invention. FIG. 2 is a plan view of the information storage medium 1. The information storage medium 1 includes a wireless communication improvement sheet body (hereinafter simply referred to as “sheet body”) 10 and a wireless IC tag 20. In FIG. 2, for easy understanding, the antenna 21 to be described later is shown with hatching.

  The sheet body 10 includes a first spacer 2, an auxiliary antenna 3, a second spacer 4, and a back conductor layer 5. The auxiliary antenna 3 is attached to the second spacer 4 with a first adhesive 3a, and the back surface. The conductor layer 5 is attached to the second spacer 4 with the second adhesive 5a.

  The wireless IC tag includes an antenna 21 for transmitting and receiving wireless radio waves, and an integrated circuit element (hereinafter referred to as “IC chip”) 22 connected to the antenna 21 and storing identification information. Further, the antenna 21 includes a loop antenna 21a and a pattern antenna 21b, and the IC chip 22 is connected to the loop antenna 21a.

  The first spacer 2 has an arrangement surface 2 a on which the wireless IC tag 20 is arranged without being connected, and is configured of a dielectric layer that insulates between the antenna 21 of the wireless IC tag 20 and the auxiliary antenna 3.

  The auxiliary antenna 3 is made of a thin metal layer provided on the surface opposite to the arrangement surface 2 a of the first spacer 2, and resonates at the communication frequency of the wireless IC tag 20. They are electromagnetically coupled and themselves function as a resonant antenna.

  The second spacer 4 is provided on the side opposite to the first spacer 2 with the auxiliary antenna 3 interposed therebetween, and is configured of a dielectric layer that insulates between the auxiliary antenna 3 and the back conductor layer 5.

  The back conductor layer 5 is made of a thin metal layer and is provided on the side opposite to the auxiliary antenna 3 with the second spacer 4 interposed therebetween.

  The first spacer 2, the auxiliary antenna 3, the second spacer 4, and the back conductor layer 5 have the same outer dimensions, and are laminated in this order to constitute the sheet body 10.

  Although the planar shape when the sheet body 10 is viewed from the stacking direction depends on the shape of the wireless IC tag 20 to be mounted, it is mostly rectangular. Moreover, the total thickness of the sheet | seat body 10 is about 0.5-15 mm.

  In the present embodiment, the planar shape of the sheet body 10 is a rectangle, and the auxiliary antenna 3 is provided with a rectangular hole (slot) S that opens at the center in the long side direction. In the plan view of FIG. 2, the position of the hole S is located substantially at the center of the sheet body 10, but is not necessarily the central portion. The hole S is provided so as to correspond to the position of the loop antenna 21 a of the wireless IC tag 20.

  As shown in the cross-sectional view of FIG. 1, the hole S penetrates the auxiliary antenna 3 in the stacking direction. The length L of the hole S is formed to be 3 to 97% of the length L0 in the short side direction of the sheet body 10 and is, for example, 3 to 194 mm.

  The width W of the hole S is provided to be equal to or longer than the inner dimension of the long side of the rectangular loop antenna 21a, and is, for example, 1 to 180 mm depending on the size of the loop antenna 21a.

  The overall shape of the wireless IC tag 20 is substantially rectangular, and as shown in FIG. 2, a loop antenna 21a is provided at the center, and pattern antennas 21b are provided extending on both sides thereof. The IC chip 22 is connected to the loop antenna 21a. The loop antenna 21a has a substantially rectangular shape and includes two long side portions 23a and 23b and two short side portions 24a and 24b. The loop antenna 21a is arranged so that the long side portions 23a and 23b are parallel to the longitudinal direction of the entire shape of the wireless IC tag 20. The sheet body 10 is also rectangular according to the overall shape of the wireless IC tag 20 as described above, and the wireless IC tag is arranged so that the longitudinal direction of the wireless IC tag 20 and the longitudinal direction of the sheet body 10 are parallel to each other. 20 is arranged on the arrangement surface 2 a of the first spacer 2.

  In the present invention, the shape of the loop antenna 21a is substantially rectangular, that is, a rectangle including a square, a rounded rectangle with corners having an R shape, and at least three sides are linear, and the remaining one side is curved. Or a shape in which a part of the remaining one side has a concave portion or a convex portion.

  The hole S of the auxiliary antenna 3 is provided at a position corresponding to the loop antenna 21a with the first spacer 2 interposed therebetween. Of the opening dimensions of the holes S, the width W is a length dimension in a direction parallel to the longitudinal direction of the sheet body 10, and the length L is a direction parallel to the short direction perpendicular to the longitudinal direction of the sheet body 10. It is a length dimension. The attachment position of the wireless IC tag 20 is changed by providing the hole S in the auxiliary antenna 3 so that the width W of the hole S is longer than the inner dimension length of the long side portions 23a and 23b of the loop antenna 21a. Therefore, the communication frequency band can be made wider.

  In the present embodiment, the overall shape of the wireless IC tag 20 and the shape of the loop antenna 21a are substantially rectangular. However, the shape is not limited to this, and may be circular or elliptical.

  When the loop antenna is circular, the whole is uniformly formed with the same width, and the width W of the hole S is longer than the inner dimension length of the diameter (corresponding to the long side of the loop antenna) of the loop antenna. When the hole S is provided in the shape of an ellipse, the whole is uniformly formed with the same width, the long axis is provided so as to be parallel to the longitudinal direction of the sheet body 10, and the width W of the hole S is The hole S is provided so as to be longer than the inner dimension of the long diameter of the loop antenna (corresponding to the long side of the loop antenna).

  Even when the width W of the hole S is shorter than the inner length of the long side portions 23a and 23b of the loop antenna 21a, the communication frequency band does not become a wide band, and the original communication of the wireless IC tag 20 is performed. Of course, wireless communication by frequency is possible, and the communication improvement function by the sheet member 10 is also exhibited.

  Further, regarding the arrangement position of the loop antenna 21a, one long side portion to which the IC chip 22 is connected among the long side portions 23a and 23b of the loop antenna 21a when viewed from the stacking direction of the sheet body 10. (In this embodiment, the long side portion 23a) is preferably located in the hole S, and the other long side portion (in this embodiment, the long side portion 23b) is provided so as to overlap the thin metal layer portion of the auxiliary antenna 3. .

  The long side portion of the loop antenna 21a on the side to which the IC chip 22 is connected is provided so as to overlap the thin metal layer portion, or the long side portion of the loop antenna 21a does not overlap the thin metal layer portion. When the entire loop antenna 21a including the portions 24a and 24b is located in the hole S, the communication frequency band cannot be sufficiently expanded.

  As the wireless IC tag 20, a commercially available product can be used, and the communication frequency band is not limited, but the effect is particularly remarkable in the wireless IC tag 20 whose communication frequency band is the UHF band.

  Furthermore, the effect becomes remarkable when the wireless IC tag 20 using the IC chip 22 conforming to the EPC Class 1 Generation 2 standard (EPC C1G2 standard) and ISO 18000-6 Type C is used. Examples of the IC chip compliant with the EPC C1G2 standard include UCODE G2iL manufactured by NXP, Higgs3 manufactured by ALIEN, and Monza4 manufactured by Impinj.

Below, the sheet | seat body 10 is further demonstrated.
The sheet body 10 of the present invention exhibits at least a communication improving function by providing the hole S in the auxiliary antenna 3, and further defines a dimension for the loop antenna 21a as described above, thereby further widening the communication frequency. The communication improving function is that the antenna 21 of the wireless IC tag 20 arranged on the arrangement surface 2a and the auxiliary antenna 3 are electromagnetically coupled through the hole S, and the auxiliary antenna 3 functions as a resonance antenna. Demonstrated.

  By providing the hole S in the auxiliary antenna 3, an electric field is generated in the hole S along the long axis direction of the antenna shape in accordance with the resonance operation of the antenna 21 of the wireless IC tag 20. And the electromagnetic coupling between the IC chip 22 and the auxiliary antenna 3 is activated. Furthermore, since the hole S increases the electrical resistance of the auxiliary antenna 3, it is possible to suppress the induced current generated in the auxiliary antenna 3 corresponding to the antenna 21 of the wireless IC tag 20.

  Through the hole S, the auxiliary antenna 3 has a function of passing electromagnetic energy without being electrically connected to the wireless IC tag 20, and also has a function of transmitting information to the IC chip 22 and a propagation path of information from the IC chip 22. By superimposing the antenna inside, in addition to the conventional antenna operation with a distant place, the operation mechanism of the transfer of electromagnetic energy with the wireless IC tag 20 in the vicinity is supported.

  The auxiliary antenna 3 is configured to resonate with the wireless communication frequency as a whole when combined with the wireless IC tag 20, and the resonance layer of the auxiliary antenna 3 may have one or a plurality of resonating parts. When the wavelength of the radio wave of the radio communication frequency is λ, the resonance part has a size that falls within a range of λ / 8 to 3λ / 4.

  As described above, the information storage medium 1 can improve the communication of the wireless IC tag 20 only by bonding the sheet 10 and the wireless IC tag 20 together. Commercially available wireless IC tags have different chip impedance values depending on their designs. This impedance differs depending on whether it is stationary or in operation, and varies depending on the amount of energy received even under operating conditions. The feature of the wireless communication improving sheet body of the present invention is that impedance matching and improvement can be realized by simply pasting the sheet body 10 on these wireless IC tags having unstable and variable impedances later.

  The first spacer 2 and the second spacer 4 insulate the wireless IC tag 20 from the auxiliary antenna 3, insulate the auxiliary antenna 3 from the back conductor layer 5, and provide a wavelength shortening effect as a dielectric layer. Thus, the resonance frequency of the auxiliary antenna 3 is adjusted. In some cases, a portion where the electric field = 0 is formed between the auxiliary antenna 3 and the back conductor layer 5, and in this case, the auxiliary antenna 3 and the back conductor layer 5 are connected to each other by providing a via in the portion where the electric field = 0. The operation is possible even if it is made conductive.

  The first spacer 2 and the second spacer 4 are only required to maintain the positional relationship such as the distance between the wireless IC tag 20 and the auxiliary antenna 3 and the distance between the auxiliary antenna 3 and the back conductor layer 5. It is preferable to use a material having a low loss, that is, a low dielectric loss tangent tan δ (ε ″ / ε ′) or magnetic tangent tan δ (μ ″ / μ ′) in the communication frequency band. For example, an air layer with a gap may be used, but it is generally preferable to use an organic material as exemplified below.

  As the organic material, for example, polymer organic materials such as rubber, thermoplastic elastomer, various plastics, wood, paper, and the like can be used. Moreover, those porous bodies can also be used. Examples of the rubber include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM rubber), ethylene-vinyl acetate rubber, butyl rubber, halogenated butyl rubber, chloroprene. Synthetic rubbers such as rubber, nitrile rubber, acrylic rubber, ethylene acrylic rubber, epichlorohydrin rubber, fluoro rubber, urethane rubber, silicone rubber, chlorinated polyethylene rubber, hydrogenated nitrile rubber (HNBR), their derivatives, or These may be modified by various modification treatments. These rubbers can be used alone or in combination.

  Examples of thermoplastic elastomers include chlorinated polyethylenes such as chlorinated polyethylene, ethylene copolymers, acrylics, ethylene acrylic copolymers, urethanes, esters, silicones, styrenes, amides, olefins, etc. Various thermoplastic elastomers and their derivatives are mentioned.

  Further, as various plastics, for example, polyethylene, polypropylene, polystyrene, polysulfone, polyimide, polyurethane, polyester, unsaturated polyester, nylon, polycarbonate, polyethylene terephthalate (PET), epoxy resin, acrylic resin, alkyd resin, AS resin, ABS resin. , Chlorinated resins such as polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, and polyvinylidene chloride; thermoplastic resins such as fluororesins, silicone resins, phenol resins, urea resins, and thermosetting resins; and Derivatives, further copolymers and recycled resins are exemplified.

  The above materials can be used as they are, or combined and modified. For example, the sheet body 10 can be downsized due to the wavelength shortening effect by combining a filler such as carbon, graphite, graphite, titanium oxide, carbon fiber, carbon tube, and graphite fiber to increase the dielectric constant. Further, a reinforced resin filled with a reinforcing material may be used, or a constituent material of the wireless IC tag or the auxiliary antenna, for example, a base material, an adhesive material, an adhesive, a covering material, or the like may be used as the spacer material.

  For example, by mixing titanium oxide as a filler in EPDM rubber and adding additives such as plasticizer, filler and anti-aging agent, it is possible to realize a spacer material having a high dielectric constant and further flexibility. .

  Examples of plasticizers include paraffinic oils, aroma oils, naphthenic oils, adipic acid polyesters, trimetic acid esters, dipentaerythritol or pyromellitic acid esters, adipic acid, phthalic acid esters, polyetheresters, and the like. Species or two or more can be used. As the filler, one or more of colloidal calcium carbonate, calcium carbonate, talc and the like can be used. As the anti-aging agent, one or more of wax, monophenol, bisphenol, polyphenol, benzimidazole, thiourea, amine-ketone, and amine can be used.

  Further, the first spacer 2 and the second spacer 4 may be the same material or different materials. In the case of different materials, for example, a PET film may be used as the first spacer 2 and a soft polyethylene may be used as the second spacer 4.

  Thereby, the flexibility which can fully follow the surface shape of the member which it is going to stick as information storage medium 1 can be given.

The dielectric material constituting the first spacer 2 and the second spacer 4 is preferably a low-density material having a density of, for example, less than 1.0 g / cm ³ .

  As such a low-density dielectric material, one or more materials selected from a porous organic material and a porous inorganic material are used. A material that does not foam may be used, or a material that does not foam may be combined with a foam material. In addition to the above, paper materials such as corrugated cardboard, wood, glass, glass fiber, and earth-based materials can be used as the spacer material.

  Any means can be used as the foaming method, but the foaming method is classified into adding a foaming agent or adding thermally expandable fine particles. There are organic foaming agents and inorganic foaming agents.

  Examples of organic foaming agents include dinitrosopentamethylenetetramine (DPT), azodicarbonamide (ADCA), p, p′-oxybisbenzenesulfonylhydrazide (OBSH), hydrazide dicarbonamide (HDCA), and the like. It is not limited to it.

  As the inorganic foaming agent, sodium hydrogen carbonate or the like is added, but is not limited thereto, and may be appropriately selected depending on the material.

  As the thermally expandable fine particles, microencapsulated thermally expandable fine particle globules and the like are added. Further, a hollow material made of inorganic and organic materials such as glass beads and glass hollow bodies may be added.

The expansion ratio is not particularly limited, but it is necessary to maintain the strength and reduce the weight. From these, the expansion ratio is preferably about 2 to 30 times.
The foam structure is not particularly limited.

  The wood is a woody material such as plywood, lauan material, particle board, MDF, etc., and is not essentially limited by the material, and a plurality of materials can be used in combination.

  Examples of the porous inorganic material include, but are not limited to, various ceramic materials, gypsum board, concrete, foamed glass, pumice, asphalt, and earth materials.

  Further, the base material of the wireless IC tag 20 and an adhesive material layer for bonding each layer can be used as the spacer material. The pressure-sensitive adhesive layer may be provided partially rather than on the entire surface. As the function of the first spacer 2, it is sufficient if the wireless IC tag 20 and the auxiliary antenna 3 are not electrically connected. Therefore, a space is provided between the air layer, that is, the wireless IC tag 20 and the auxiliary antenna 3. It may be done.

  For the first spacer 2 and the second spacer 4, it is necessary to change the received radio wave energy to transmission energy without loss as much as possible. Therefore, it is necessary to select a material with as little energy loss as possible. For this purpose, the dielectric loss tangent tan δ (ε ″ / ε ′) is preferably 0.5 or less, more preferably 0.2 or less, at the frequency of the electromagnetic wave used by the wireless IC tag 20 for wireless communication.

  The spacer material preferably has a high dielectric constant, flexibility, and low dielectric loss tangent tan δ (ε ″ / ε ′), but more importantly, it exhibits a low dielectric loss tangent tan δ in a communication frequency band (UHF band, etc.). It is.

  Further, if the real part ε ′ of the complex relative dielectric constant is high, the sheet size can be reduced and the size can be reduced. Therefore, ε ′ is preferably 1 to 50. However, the sheet is composed of various parameters, and is not limited to the above numerical values.

The auxiliary antenna 3 and the back conductor layer 5 are made of a conductive material having conductivity.
The conductive material constituting the auxiliary antenna 3 and the back conductor layer 5 may be a metal such as gold, platinum, silver, nickel, chromium, aluminum, copper, zinc, lead, tungsten, iron, etc. It may be a metal powder, a resin mixture mixed with a conductive carbon material, or a film of a conductive resin. The metal or the like may be processed into a foil shape, a plate shape, a sheet shape, a film shape, or the like. Or you may have the structure by which the metal thin layer of film thickness, for example, 600 mm, was formed on the synthetic resin film. What transferred metal foil to base materials, such as a film or cloth, may be used. Further, conductive ink (for example, resistivity of 10Ω / sq. Or less) may be applied to the first spacer 2 and the second spacer 4.

  The size of the resonance layer of the auxiliary antenna 3 is determined according to the wavelength corresponding to the radio wave of a specific frequency, but the size of the back conductor layer 5 is not limited. Further, the back conductor layer 5 may not be attached to a material having electromagnetic shielding properties such as affixing only to a metal product, that is, a material having a function equivalent to that of the back conductor layer.

  The hole S can be formed in the conductor layer by a general forming method. In the first spacer 2, a predetermined part that becomes a hole or a notch is removed from a plate-like member made of a dielectric material by using mechanical processing such as punching or cutting, or chemical processing such as etching. That's fine. Further, depending on the dielectric material used, it is possible to mold into a shape in which holes or notches are provided in advance at the time of molding.

  Similarly to the first spacer 2, the auxiliary antenna 3 may be mechanically or chemically processed to remove a predetermined portion that becomes a hole or notch. Moreover, it is also possible to print, vapor-deposit, and apply | coat directly on dielectric layers, such as PET film, so that it may become a shape by which the notch was previously provided.

  The hole S is provided in the auxiliary antenna 3. However, the same hole S as the hole S provided in the auxiliary antenna 3 may be formed in each of the first spacer 2 and the auxiliary antenna 3. The auxiliary antenna 3 may be laminated on the spacer 2 in advance, and a simultaneous hole or notch may be formed in both.

  The hole S only needs to increase the electrical resistance of the auxiliary antenna 3 made of a conductor layer, and the width dimension only needs to be longer than the length of the long side portion of the loop antenna 21a as described above.

  Originally, in the wireless IC tag 20, wireless communication is disturbed near a metal member made of a conductive material and the communication distance is shortened. However, the communication distance is improved by using the sheet body 10.

(Embodiment 1) Examination of the width dimension of the hole S provided in the auxiliary antenna 3 The information storage medium 1 is actually formed, the width dimension of the hole S is changed, and the frequency characteristic of the communication distance of the information storage medium 1 is changed. It was measured.

  The sheet body 10 had outer dimensions of 28 mm in length and 120 mm in width. As the first spacer 2, a PET (Polyethylene terephthalate) film having a thickness of 0.1 mm was used. The auxiliary antenna 3 is an aluminum foil layer having a thickness of 0.05 mm, and the hole S has a length L of 20 mm and a width W of 4 to 45 mm. As the second spacer 4, two foam materials having a thickness of 2 mm (foaming magnification: 5 times) were bonded together. The back conductor layer 5 was an aluminum foil layer having a thickness of 0.05 mm.

  The wireless IC tag 20 used was ALN-9640 manufactured by ALIEN TECNOLOGY, and the inner length of the long side portion of the loop antenna was 24 mm. Further, when viewed from the stacking direction, one long side portion 23a to which the IC chip 22 was connected was disposed in the hole S, and the other long side portion 23b was disposed so as to overlap the aluminum foil layer.

  FIG. 3 is a graph illustrating the frequency characteristics of the communication distance according to the first embodiment. The horizontal axis indicates the frequency (MHz), and the vertical axis indicates the communication distance (m). Plot A shows the case of W = 4 mm, Plot B shows the case of W = 11 mm, Plot C shows the case of W = 15 mm, Plot D shows the case of W = 24 mm, Plot E Represents the case of W = 27 mm, plot F represents the case of W = 30 mm, plot G represents the case of W = 40 mm, and plot H represents the case of W = 45 mm.

  As can be seen from the graph, from plot A to plot C, a resonance frequency shift was observed, but the resonance band remained narrow. On the other hand, the plots D to H are significantly different from the frequency characteristics of the plots A to C, and a resonance band of 50 MHz or more can be secured.

  In plots D to H in which the resonance band is wide, W of the hole S is 24 mm, 27 mm, 30 mm, 40 mm, and 45 mm, and the length of the long side portion of the loop antenna 21a is longer than the inner dimension length (24 mm). That was it.

(Example 2) Examination of position of loop antenna of auxiliary antenna 3 The same sheet body 10 and wireless IC tag 20 as those of Example 1 were used. The width of the hole S was W = 40 mm.

  The frequency characteristics of the communication distance of the information storage medium 1 when the attachment position of the wireless IC tag 20 was changed were measured. Specifically, the distance from the long side of the sheet body 10 to the long side portion of the loop antenna 21a of the wireless IC tag 20 was changed to 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, respectively.

  FIG. 4 is a graph illustrating the frequency characteristics of the communication distance according to the second embodiment. The horizontal axis indicates the frequency (MHz), and the vertical axis indicates the communication distance (m). Plot I shows the case where the distance is 1 mm, Plot J shows the case where the distance is 2 mm, Plot K shows the case where the distance is 3 mm, Plot L shows the case where the distance is 4 mm, Plot M Indicates a case where the distance is 5 mm.

  As can be seen from the graph, the shorter the distance from the long side of the sheet body 10 to the long side portion of the loop antenna 21a of the wireless IC tag 20, the wider the resonance band. This is because the other long side portion 23b of the loop antenna 21a, to which the IC chip is not connected, is arranged so as to overlap the aluminum foil layer of the auxiliary antenna 3, and the resonance band becomes closer to the end on the long side side. It shows that it becomes wide.

(Comparative example) Examination of the structure which changed the hole into the notch As a comparative example, the sheet | seat body of the structure which provided not the hole S but the notch in the auxiliary antenna was produced, and the frequency characteristic of the communication distance was measured.

  The outer dimensions and the like of the sheet body of the comparative example are the same as those of Examples 1 and 2, and a notch opened on the long side is provided instead of the hole S. The width of the notch was changed to 30 mm, 40 mm, 50 mm, and 60 mm.

  FIG. 5 is a graph showing the frequency characteristics of the communication distance of the comparative example. The horizontal axis indicates the frequency (MHz), and the vertical axis indicates the communication distance (m). Plot N shows a case where the width is 30 mm, Plot O shows a case where the width is 40 mm, Plot P shows a case where the width is 50 mm, and Plot Q shows a case where the width is 60 mm.

  As can be seen from the graph, the width of the notch was widened, but the communication frequency was not wide. Therefore, it has been found that in order to widen the communication frequency band, it is necessary to provide a hole in the auxiliary antenna 3 with a specific dimension instead of a notch.

DESCRIPTION OF SYMBOLS 1 Information storage medium 2 1st spacer 3 Auxiliary antenna 4 2nd spacer 5 Back surface conductor layer S hole 10 Wireless communication improvement sheet | seat body 20 Wireless IC tag 21 Antenna 21a Loop antenna 21b Pattern antenna 22 IC chip

Claims (3)

A wireless IC tag comprising a loop antenna and an integrated circuit element connected to the loop antenna and storing identification information;
A first spacer having an arrangement surface on which the wireless IC tag is arranged;
An auxiliary antenna provided on a surface of the first spacer opposite to the arrangement surface, the inner dimension of the long side of the loop antenna at a position corresponding to the loop antenna across the first spacer An auxiliary antenna comprising a conductor layer provided with a hole having a width equal to or greater than the length;
An information storage medium comprising: a second spacer provided on a side opposite to the first spacer with the auxiliary antenna interposed therebetween. The integrated circuit element is connected to one long side of the loop antenna,
The loop antenna is provided so that the one long side is positioned in the hole and the other long side overlaps the conductor layer when viewed from the stacking direction. The information storage medium described.   3. The information storage medium according to claim 1, wherein the wireless IC tag conforms to an EPC Class 1 Generation 2 standard, and a communication frequency band is a UHF band.

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