JP5886100B2 - Wireless IC tag - Google Patents

Description

  The present invention relates to a wireless IC tag used for a wireless communication system (RFID) that automatically reads and writes information by wireless communication with a reader and a writer.

  A wireless IC tag is used in a wireless communication system (RFID) that automatically reads and writes information by wireless communication with a reader and writer, and is used for process management in logistics and factories.

  For example, Patent Document 1 discloses a conductive layer 6 having a predetermined antenna shape, an IC chip 3 mounted on one surface of the conductive layer 6, and provided on the other surface of the conductive layer 6. A UHF band wireless IC tag label including an adhesive resin layer 7 temporarily bonded so as to be peelable is described. This UHF band wireless IC tag label is thin and flexible and can be attached to a curved surface. Also, continuous printing with a printer is possible.

  In order to improve the strength of wireless IC tags, or to improve heat resistance and solvent resistance in the environment of use, wireless devices that cover the entire circumference of the tag with cover materials such as wood, plastic, rubber, glass, paper, etc. There is an IC tag. For example, Patent Document 2 discloses a wireless IC tag in which the entire circumference of an inlet including an antenna and an IC chip is covered with silicone rubber or vulcanized rubber in order to improve chemical resistance and the like.

International Publication No. WO2008 / 053702 Pamphlet JP 2009-238022 A

  However, when the wireless IC tag label described in Patent Document 1 is attached to a conductor typified by wood, plastic, glass or the like, or a conductor typified by metal or the like, the wavelength shortening effect by the dielectric or the conductor The reactance of the antenna of the wireless IC tag changes due to the capacitive coupling, and the matching between the antenna and the IC chip at the communication frequency deteriorates, so that the communication performance deteriorates. In particular, when the adherend is a metal, the communication performance is significantly reduced. Therefore, when using the UHF band wireless IC tag label described in Patent Document 1, it is necessary to adjust the resonance of the antenna by changing the shape of the wireless IC tag (antenna shape, etc.) depending on the object to be attached. As a result, the cost of the wireless IC tag is increased.

  Also, for example, a wireless IC tag covered with a cover material such as the wireless IC tag described in Patent Document 2 can improve the strength and the like. However, since it is affected by the cover material, the communication performance is similar to the above. There is a problem that decreases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless IC tag that can easily and inexpensively match the reactance of an antenna and suppress deterioration in communication performance due to an object to be attached. Is to provide.

In order to solve the above-described problems, a wireless IC tag according to the present invention includes an antenna including a first conductor layer and an opening formed in the first conductor layer, and a direction orthogonal to the main surface of the antenna. An IC chip disposed on the first conductor layer and an insulating layer covering both surfaces of the first conductor layer and the IC chip are provided so as to divide the opening as viewed from the side. Then, on the opposite side of the antenna across the insulating layer, a part of the first hole defined by the first conductor layer and the IC chip when viewed from the direction orthogonal to the main surface of the antenna overlap, is installed in several places multiple, the second conductor layer composed of one or more layers is provided. Furthermore, the circumference of the second hole defined by the first conductor layer, the second conductor layer, and the IC chip is shorter than the circumference of the first hole.

  According to the present invention, by providing the second conductor layer, the reactance of the antenna of the wireless IC tag can be readjusted, and the resonance state can be improved. In addition, the present invention is implemented by attaching the second conductor layer to a general-purpose wireless IC tag. As described above, it is possible to suppress a decrease in communication performance easily and at low cost.

It is a figure which shows the radio | wireless IC tag which concerns on 1st Embodiment of this invention, (a) is sectional drawing, (b) is a top view. (A)-(c) is sectional drawing which shows the radio | wireless IC tag which changed the position of the 2nd conductor layer of the radio | wireless IC tag shown in FIG. FIG. 6 is a cross-sectional view illustrating a modification of the wireless IC tag illustrated in FIG. 1, in which (a) is a first modification, (b) is a second modification, (c) is a third modification, and (d) is a first modification. 4 modification, (e) is a 5th modification. It is a top view of the radio | wireless IC tag used for an Example. It is a figure which shows the method of measuring the communication distance of a wireless IC tag.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the present invention, a wireless IC tag that performs wireless communication using radio waves in the UHF band will be described. However, the present invention can also be applied to a wireless IC tag that performs wireless communication using radio waves in other frequency bands.

(First embodiment)
1A and 1B are diagrams showing a wireless IC tag according to the first embodiment, where FIG. 1A is a cross-sectional view taken along the line Ia-Ia, and FIG. 1B is a plan view (a plan view of the wireless IC tag 1 viewed from the spacer 7 side. Figure). In FIG. 1B, the adhesive layer 5b and the spacer 7 are seen through so that the structures of the antenna 2 and the IC chip 4 can be easily understood.

(Configuration of wireless IC tag 1)
As shown in FIG. 1, the wireless IC tag 1 includes an antenna 2, an insulating layer 3, an IC chip 4, an adhesive layer (5a, 5b), a second conductor layer 6, a spacer 7 (dielectric layer), and a protective sheet. 8 is included. The wireless IC tag 1 is attached to an article 100 made of, for example, glass, acrylic, wood, paper (corrugated cardboard), metal, etc., wirelessly communicates with a reader (not shown), and is used for logistics and factory process management.

(Antenna 2)
As shown in FIG. 1B, the antenna 2 has a rectangular plate-like first conductor layer 11 with an opening 12 formed therein, and a general-purpose antenna is used. The material of the first conductor layer 11 is not particularly limited as long as it is a material having high electrical conductivity. For example, a metal such as aluminum, copper, or iron, an alloy material, or a carbon-based material such as carbon is used. it can.

  Here, in the antenna 2, the length of the antenna 2 (the length in the longitudinal direction of the first conductor layer 11) is larger than the width of the antenna 2 (the length in the short direction of the first conductor layer 11). (May be the same). The width of the antenna 2 is not less than 2.5% of the wavelength of the radio wave used for communication and not more than the length of the antenna 2. This is because the communication distance of the wireless IC tag 1 decreases if the width of the antenna 2 is less than 2.5% of the wavelength of the radio wave used for communication. The length is preferably 4.0% or more and not more than the length of the antenna 2. However, it is not essential that the width of the antenna 2 is 2.5% or more of the wavelength of the radio wave used for communication.

  The opening 12 is a notch groove that penetrates the main surface 2a of the first conductor layer 11 and is formed in a T shape. In FIG. 1B, the opening 12 is a portion that connects the circumference of the first conductor layer 11 in the order of a to j. Note that the term “tie” as used in the present application means tying so as to follow the shape of the circumference. The shape of the cutout groove of the opening 12 is not limited to the above shape, and may be another shape such as an S shape, a J shape, or a rectangle. Moreover, the opening part 12 is not restricted to a notch groove, A hole may be sufficient. As the shape of the hole, for example, a T shape, an H shape, or a rectangular shape is generally used.

(Insulating layer 3)
The insulating layer 3 is a layer that covers the entire circumference of the antenna 2 and the IC chip 4. Therefore, the antenna 2 and the IC chip 4 are electrically insulated from other members. The material of the insulating layer 3 is not particularly limited as long as it is an insulating material. For example, a resin such as PET or epoxy resin, paper, or an insulating adhesive can be used. In the present application, among the two main surfaces 2a of the antenna 2, the insulating layer 3 that covers the protective sheet 8 side in particular is referred to as the insulating layer 3a, and the insulating layer 3 that covers the spacer 7 side is referred to as the insulating layer 3b.

(IC chip 4)
As shown in FIG. 1B, the IC chip 4 is fixed (arranged) to the first conductor layer 11 so as to divide the opening 12 when viewed from the direction orthogonal to the main surface 2 a of the antenna 2. Specifically, protrusions (2b, 2c: particularly protrusions provided on the portion connecting a and b are formed on the portion connecting a and b and the portion connecting i and j in the circumference of the first conductor layer 11 with 2b. , I and j are provided with protrusions 2c), and the IC chip 4 is joined to these protrusions (2b, 2c). As a result of the IC chip 4 being arranged so as to divide the opening 12, a hole 21 (first hole) is defined by the first conductor layer 11 and the IC chip 4. In FIG. 1B, the hole 21 is a portion that connects the circumference of the first conductor layer 11 and the outer circumference of the IC chip 4 in the order of b → c → d → e → f → g → h → i → b. .

  In the present embodiment, the IC chip 4 is fixed to the insulating layer 3a side of both surfaces of the first conductor layer 11. However, the IC chip 4 may be fixed to the insulating layer 3b side. The projections (2b, 2c) may be fixed so as to be sandwiched up and down. The IC chip 4 used in the present embodiment is a general-purpose one including a data storage area (memory).

(Spacer 7)
A spacer 7 (dielectric layer) is bonded to the opposite side of the antenna 2 with the insulating layer 3b interposed therebetween via an adhesive layer 5b (however, fixing is not limited to bonding). In addition, although it seems that the clearance gap is open between the adhesion layer 5b and the spacer 7 by providing the 2nd conductor layer 6 (it mentions later for details), it is closely_contact | adhering. The wireless IC tag 1 is attached to the article 100 by attaching the spacer 7 to the article 100 via an adhesive layer or the like.

The spacer 7 is a dielectric layer, and suppresses a decrease in communication performance due to the influence of the article 100. The spacer 7 is preferably used when the article 100 is a material that significantly reduces communication performance such as metal. When the article 100 is a conductor, the spacer 7 does not electrically connect the second conductor layer and the article 100 in a DC manner. The thickness of the spacer 7 is preferably as thick as possible, and is preferably at least thicker than the thickness of the antenna 2 and further thicker than the portion of the wireless IC tag 1 excluding the spacer 7. The spacer 7 is not essential.

(Protective sheet 8)
A protective sheet 8 is bonded to the opposite side of the antenna 2 with the insulating layer 3a interposed therebetween via an adhesive layer 5a (however, fixing is not limited to bonding). The protective sheet 8 serves to protect the antenna 2, the IC chip 4, and the like, and characters and the like can be printed on the surface opposite to the adhesive layer 5 a. The protective sheet 8 is not essential.

(Second conductor layer 6)
Between the insulating layer 3b and the spacer 7, the 2nd conductor layer 6 is adhere | attached through the adhesion layer 5b. The second conductor layer 6 is a rectangular plate-like member, and the width (short direction, depth of the first conductor layer 11) is the same as that of the first conductor layer 11, and the length (first conductor layer 11). The longitudinal direction of the body layer 11 is narrower than that of the first conductor layer 11. As the material of the second conductor layer 6, similarly to the first conductor layer 11, for example, a metal such as aluminum, copper, or iron, an alloy material, or a carbon-based material such as carbon can be used. The first conductor layer 11 and the second conductor layer 6 may be made of the same material or different materials. As shown in FIG. 1B, the second conductor layer 6 overlaps a part of the hole 21 (first hole) when viewed from the direction orthogonal to the main surface 2a of the antenna 2, and the hole 21 It is arranged so as not to break up. As a result, a hole 22 (second hole) is defined by the first conductor layer 11, the second conductor layer 6, and the IC chip 4. In FIG. 1 (b), the holes 22 are defined as b → c → d → e → f ′ → g ′ → the circumference of the first conductor layer 11, the circumference of the second conductor layer 6, and the outer periphery of the IC chip 4. It is the part which connects in order of h->i-> b.

  Here, the circumference of the hole 22 (second hole) is shorter than the circumference of the hole 21 (first hole). The peripheral length of the hole 22 is the length of the portion defining the hole 22 in the periphery of the first conductor layer 11, the periphery of the second conductor layer 6, and the outer periphery of the IC chip 4. Is the length of the portion defining the hole 21 in the circumference of the first conductor layer 11 and the outer circumference of the IC chip 4. For example, in FIG. 1B, the circumferential length of the hole 22 is the length of the portion connecting in the order of b → c → d → e → f ′ → g ′ → h → i → b. The length is the length of the portion connecting in the order of b → c → d → e → f → g → h → i → b. Accordingly, in FIG. 1B, the circumferential length of the hole 22 is shorter than the circumferential length of the hole 21 by the lengths of f → f ′ and g → g ′.

  The degree of improvement in the communication distance of the wireless IC tag 1 depends on the circumference of the hole 22 (second hole). However, since the degree of improvement in the communication distance varies depending on the material of the article 100 to which the wireless IC tag 1 is attached, the shape of the antenna, and the like, the circumference of the hole 22 cannot be uniquely determined. Therefore, the peripheral length of the hole 22 is appropriately designed according to the material of the article 100, the shape of the antenna, and the like. Note that the degree of improvement in the communication distance does not depend on the shape of the second conductor layer 6. Therefore, the shape of the second conductor layer 6 can be various as long as the circumference of the hole 22 is a design value.

  Further, the portion of the second conductor layer 6 that overlaps the first conductor layer 11 when viewed from the direction orthogonal to the main surface 2 a of the antenna 2 is a portion that cannot participate in the circumferential length of the hole 22. Does not affect communication performance. Therefore, the shape and size of the portion of the second conductor layer 6 that overlaps the first conductor layer 11 are not particularly limited. Therefore, although the width of the second conductor layer 6 is the same as the width of the first conductor layer 11 in the present embodiment, it is not necessary to be the same.

  The second conductor layer 6 is electrically insulated from the first conductor layer 11 by the insulating layer 3b. In the case of short-circuiting, the insulating layer 3b needs to be peeled off and connected, which complicates the process. Furthermore, if the short circuit occurs, the contact resistance is affected by the contact state and the performance becomes unstable. Therefore, the second conductor layer 6 and the first conductor layer 11 are insulated by the insulating layer 3b. Furthermore, the second conductor layer 6 should not overlap the entire hole 21. This is because the antenna 2 cannot function as an antenna having an opening when the second conductor layer 6 overlaps the entire hole 21.

  As described above, in the wireless IC tag 1 according to the present embodiment, the antenna 2 is an antenna having the opening 12, and the second conductive layer overlaps with a part of the hole 21 defined by the opening 12 and the IC chip 4. The body layer 6 is provided, and the circumference of the hole 22 is shorter than the circumference of the hole 21. As a result, when a normal wireless IC tag is attached to an article having a high dielectric constant, the communication distance is reduced as compared with use in free space. However, if the wireless IC tag 1 of the present invention is used, the wireless IC tag 1 The reactance of the antenna 2 can be made close to the reactance value in the free space, and the reduction in communication distance can be improved.

  A normal wireless IC tag is designed and manufactured so as to obtain the maximum communication distance in free space, and has an opening in the antenna as a resonance adjustment circuit for obtaining the maximum communication distance. A loop current flowing along the edge of the hole defined by the opening and the IC chip (that is, corresponding to the first hole of the present invention) serves as the reactance of the antenna. When this wireless IC tag is affixed to an article with a high dielectric constant (eg, glass, acrylic plate, wood, paper, metal), the antenna of the wireless IC tag has a wavelength shortening effect due to the dielectric and capacitive coupling with the conductor. The reactance changes, and the resonance state is deteriorated and the communication distance is reduced as compared with use in free space.

  However, like the wireless IC tag 1 of the present invention, the second conductor layer 6 is overlapped with a part of the hole 21 so that the circumference of the hole 22 is shorter than the circumference of the hole 21. The inductance caused by the loop-shaped current constituted by 22 can be reduced, and the reactance of the antenna 2 of the wireless IC tag 1 can be readjusted. This is because the second conductor layer 6 is superposed on the second conductor layer 6 from the loop current of the opening 12 of the first conductor layer 11 that is induced when the wireless IC tag 1 receives radio waves. This is because new loop-shaped currents are induced and electromagnetic fields due to these currents interfere with each other, so that the apparent path of the current flowing in the outer periphery of the opening 12 changes. As a result of the readjustment of reactance in this way, the state of resonance is improved, and a decrease in communication distance can be suppressed.

  Next, the variation of the arrangement position of the 2nd conductor layer 6 is demonstrated, referring FIG. 2A to 2C are cross-sectional views showing the wireless IC tags 1a to 1c in which the positions of the second conductor layers 6 of the wireless IC tag 1 shown in FIG. 1 are changed. However, in FIG. 2, components having the same configuration as the wireless IC tag 1 shown in FIG. 1 are denoted by the same reference numerals.

  In the wireless IC tag 1 described above, the second conductor layer 6 is disposed between the insulating layer 3 b and the spacer 7, but the second conductor layer 6 is insulated from the first conductor layer 11. (That is, on the opposite side of the antenna 2 with the insulating layer 3 interposed therebetween), it may be disposed anywhere. For example, as shown to Fig.2 (a), you may arrange | position between the insulating layer 3a and the protective sheet 8, and as shown in FIG.2 (b), insulating layer 3a among both surfaces of the protective sheet 8 is sufficient. It may be arranged on the opposite surface (that is, the printing surface of characters, etc.), or as shown in FIG. 2 (c), arranged on the opposite surface of the spacer 7 from the insulating layer 3b. You can also

  That is, in the present application, “on the opposite side of the antenna 2 (* 2) across the insulating layer 3 (* 1)” means “on the surface of the insulating layer 3 opposite to the antenna 2”. If it is the side opposite to the antenna 2, it means that another layer such as the spacer 7 and the protective sheet 8, a coating layer 31 described later, a case 32, and the like may be interposed. Here, the meaning is the same even if (* 1) and (* 2) are replaced with other configurations (spacer 7 or the like).

(Modification)
Next, a modification of the wireless IC tag of the present invention will be described with reference to FIG. 3A and 3B are cross-sectional views showing a modification of the wireless IC tag shown in FIG. 1A. FIG. 3A is a first modification, FIG. 3B is a second modification, and FIG. 3C is a third modification. For example, (d) shows a fourth modification, and (e) shows a fifth modification. In FIG. 3, components having the same configuration as the wireless IC tag 1 of the first embodiment are denoted by the same reference numerals.

(First modification)
As shown in FIG. 3A, the wireless IC tag 101 according to the first modification has a hollow body 7a (member) instead of the spacer 7, and thus the wireless IC tag according to the first embodiment. Different from 1. The hollow body 7a (member) is a member made of a resin or the like having substantially the same size as the spacer 7 and having a gap 7b inside. Also with this hollow body 7a (member), a decrease in communication performance due to the influence of the article 100 can be suppressed, as in the case where the spacer 7 is provided. The member is not limited to the hollow body 7a as long as a gap is provided between the insulating layer 3b and the article 100 as long as it is an insulating material or a dielectric material. For example, the cross-sectional area is smaller than the main surface 2a. In addition, a connection member (one or a plurality of support columns, a spring, a linear member, or the like) that connects the insulating layer 3b and the article 100 may be used.

(Second modification)
As shown in FIG. 3B, the wireless IC tag 201 according to the second modification is the first embodiment in that a third conductor layer 9 is provided on the opposite side of the antenna 2 with the spacer 7 interposed therebetween. Different from the wireless IC tag 1 according to the embodiment. As the material of the third conductor layer 9, as in the first conductor layer 11 and the second conductor layer 6, for example, a metal such as aluminum, copper or iron, an alloy material, or a carbon-based material such as carbon is used. be able to. By providing the third conductor layer 9, the third conductor layer 9 shields the influence of the object 100 on the back surface. Therefore, when the wireless IC tag is attached to a high dielectric such as water or ceramic, the wireless IC tag Thus, it is possible to provide a wireless IC tag 1 that suppresses a decrease in communication performance due to an article to which 1 is attached. Note that the above-described members (hollow bodies 7a and the like) are provided instead of the spacers 7, and a third conductor layer 9 (third conductor layer) is provided on the opposite side of the antenna 2 with the members interposed therebetween. It may be.

(Third Modification)
As shown in FIG. 3C, the wireless IC tag 301 according to the first modification has the two second conductor layers (6a, 6b), and thus the wireless IC tag according to the first embodiment. Different from tag 1. The second conductor layer 6a is disposed between the insulating layer 3a and the adhesive layer 5a. On the other hand, the second conductor layer 6b is disposed between the adhesive layer 5b and the spacer 7, and is located at a position different from the second conductor layer 6a when viewed from the direction orthogonal to the main surface 2a of the antenna 2. Is arranged. In addition, these two 2nd conductor layers (6a, 6b) are arrange | positioned so that it may overlap with a part of hole 21, respectively, and the hole 21 may not be divided. As described above, a plurality of (or three or more) second conductor layers may be provided. Further, the positions at which the plurality of second conductor layers are provided can be various positions.

  The second conductor layer 6a is configured by stacking two second conductor layers 6aa and 6ab, and the second conductor layer 6b is configured by stacking two second conductor layers 6ba and 6bb. Has been. As described above, a plurality of (or three or more) second conductor layers may be laminated. Note that the second conductor layers 6aa, 6ab, 6ba, and 6bb shown in FIG. 3C are all assumed to have the same shape and the same material, but the shape and the material may be different from each other.

(Fourth modification)
As shown in FIG. 3D, the wireless IC tag 401 according to the fourth modification does not have the adhesive layers (5a, 5b), the spacer 7, and the protective sheet 8, and covers the entire circumference of the insulating layer 3. The wireless IC tag 1 is different from the wireless IC tag 1 according to the first embodiment in that the layer 31 is covered.

  The covering layer 31 is made of, for example, rubber or resin, and serves to protect the antenna 2, the IC chip 4, and the like. And compared with the case where the protective sheet 8 is coat | covered, the intensity | strength of a wireless IC tag, heat resistance, a weather resistance, chemical resistance, etc. are excellent. In the case of a normal wireless IC tag, when it is covered with the covering layer 31, the communication performance is lowered as in the case of being attached to the article 100. However, in this embodiment, since the 2nd conductor layer 6 is provided, the fall of communication performance can be suppressed. As a result, it is possible to improve the strength and the like of the wireless IC tag while suppressing a decrease in communication performance.

  In the present embodiment, the spacer 7, the protective sheet 8, and the like are removed and the coating layer 31 is coated, but the coating may be performed without removing these. Moreover, although the 2nd conductor layer 6 is attached to the insulating layer 3b, it may be attached to the insulating layer 3a, and can also be attached to the upper surface 31a and the lower surface 31b of the coating layer 31. Further, in this application, “covering the entire circumference of the insulating layer 3 with the coating layer 31” does not mean that the entire circumference of the insulating layer 3 is directly coated with the coating layer 31, but once the spacer 7 or the protective sheet. This includes covering with 8 or the like with the covering layer 31 (that is, indirectly covering the insulating layer 3).

(5th modification)
As shown in FIG. 3 (e), the wireless IC tag 501 according to the fifth modification is configured such that the wireless IC tag 1 according to the first embodiment closes the rectangular parallelepiped housing 33 having one open surface and the one surface. The wireless IC tag 1 is different from the wireless IC tag 1 according to the first embodiment in that it is housed in a case 32 including a lid 34.

  The case 32 is made of, for example, plastic (may be ceramic or rubber) and serves to protect the antenna 2, the IC chip 4, and the like. And compared with the case where it is not accommodated in case 32, the intensity | strength of a wireless IC tag, heat resistance, a weather resistance, chemical resistance, etc. are excellent. In the case of a normal wireless IC tag, when it is housed in the case 32, the communication performance is lowered as in the case of being attached to the article 100. However, in this embodiment, since the 2nd conductor layer 6 is provided, the fall of communication performance can be suppressed. As a result, it is possible to improve the strength and the like of the wireless IC tag while suppressing a decrease in communication performance.

  In the present embodiment, the wireless IC tag 1 is accommodated in the case 32. However, it is sufficient that at least the antenna 2, the IC chip 4, the insulating layer 3, and the second conductor layer 6 are accommodated. That is, the spacer 7, the protective sheet 8, etc. may be removed from the wireless IC tag 1 and stored in the case 32. The second conductor layer 6 is attached to the insulating layer 3b via the adhesive layer 5b, but may be attached to the insulating layer 3a via the adhesive layer 5a, or attached to the upper surface 32a and the lower surface 32b of the case 32. You can also. Further, it can be attached to the inner surface of the case 32.

(Example)
Next, the wireless communication distance was measured using the wireless IC tag with the second conductor layer as an example and the wireless IC tag without the second conductor layer as a comparative example. Hereinafter, the measurement results will be described.

First, the wireless IC tag 1 ′ used in the embodiment will be described with reference to FIG. FIG. 4 is a plan view of the wireless IC tag used in the example. The wireless IC tag 1 ′ is a wireless IC having an antenna 2 ′ including a first conductor layer 11 ′ and an opening 12 ′, an insulating layer (not shown), an IC chip 4, and a second conductor layer 6. It is a tag. On the other hand, the wireless IC tag (not shown) used in the comparative example is a tag in which the second conductor layer 6 is not attached to the wireless IC tag 1 ′ used in the example. Hereinafter, the fixing dimensions and materials of each member of the wireless IC tag 1 ′ are shown below.
1. Important dimensions Antenna 2 '
Length L1: 93mm
Width W1: 19mm
Slit 12 '
Length L2: 31mm
Width t: 1.4mm
Curvature: 0.02
2. Material Antenna 2 ': Aluminum Insulating layer 3': PET

  The antenna 2 ′ and the insulating layer (not shown) used for the wireless IC tag 1 ′ are antennas corresponding to the antenna 2 and the insulating layer 3 of each embodiment. However, as shown in FIG. 4, the antenna 2 ′ has a point that the opening 12 ′ has a curvature, and an arc-shaped notch is provided in a part of the first conductor layer 11 ′. Different from antenna 2. Also, the insulating layer (not shown) has the same shape as the antenna 2 ′ and is different from the insulating layer 3. However, the IC chip 4 used for the wireless IC tag 1 ′ is the same as the IC chip 4 of each embodiment (therefore, the same reference numerals are given).

Example 1
This wireless IC tag 1 ′ is an example, a tag in which the second conductor layer 6 is not attached to the wireless IC tag 1 ′ is a comparative example, and each tag is attached to a management object (article), and the communication distance is set. It was measured. Here, the second conductor layer 6 is made of aluminum, the width W is fixed at 19 mm which is the same as the width of the antenna 2 ′, and the length L is variable. Further, as shown in FIG. 4, the second conductor layer 6 was attached so that one end 6x coincided with the reference line S and the other end 6y overlapped with the slit 12 ′. The reference line S is a line provided 1 mm outside from one end 12′a of the opening 12 ′. The communication distance was measured by a normal measuring method shown in FIG. FIG. 5 is a diagram illustrating a method for measuring the communication performance of the wireless IC tag. ICT-5050 (circular polarization antenna) manufactured by NEC TOKIN Corporation is used as the reader antenna, and ICT-5047-20 manufactured by NEC TOKIN Corporation (transmitting output: 30 dBm, number of channels: 9 channels, channel width) : 200 kHz, supported protocol: UHF band EPCglobal Class1 Gen2 compliant). Note that the wireless IC tag 1 ′ is assumed to be used particularly at 950 MHz among the radio waves in the UHF band, so the communication distance at 950 MHz was measured in this example (the same applies to other examples).

Table 1 shows the measurement results. The explanation of each item in Table 1 (limited to those requiring explanation) is as follows (the same applies to Tables 2 to 4 described later). In Table 1, the length L of the second conductor layer 6 is varied, and the result with the value of the length L when the communication distance becomes the longest is described.
Explanation of each item Spacer 7: Foam (material: PE), width 23 mm × length 97 mm × thickness 2 mm
Communication distance ratio (%): communication distance / communication distance in free space (see Comparative Example 10) × 100

  As can be seen from Table 1, in the wireless IC tag 1 ′ (example), the communication distance is improved for any management object as compared with the tag (comparative example) in which the second conductor layer 6 is not attached. It was observed. Also, it can be seen that the communication distance is longer when the spacer 7 is provided than when the spacer 7 is not provided. From the above, it was found that the communication distance can be improved for any managed object (article) by providing the second conductor layer 6.

(Example 3)
This time, the length L of the second conductor layer 6 was fixed, the width W was varied, and the communication distance was measured. Table 2 shows the measurement results. The width W is 23 mm which is longer than the width W1 of the antenna 2 ′, 19 mm which is the same as the width W1 of the antenna 2 ′, and 4 mm which is shorter than the width W1 of the antenna 2 ′ and longer than the width t of the opening 12 ′ (opening 12 ′ The width can be changed to three.

  Regardless of whether the management object is an acrylic plate or a stainless steel plate, the communication distance was almost the same when the length of the width W was changed. From the above, it has been found that the portion of the second conductor layer 6 other than the portion covering the opening 12 ′ (strictly, the first hole) hardly affects the communication performance.

Example 4
Next, the communication distance was measured by varying the width W1 of the antenna 2 ′ that was fixed in (Example 1) to (Example 3) (that is, by cutting the first conductor layer 11 ′). . Table 3 shows the measurement results. However, the first conductor layer 11 ′ was cut so that the hole (first hole) defined by the first conductor layer 11 ′ and the IC chip 4 was not cut. The width W of the second conductor layer 6 is also cut in accordance with the first conductor layer.

  It has been found that the communication distance decreases when the width W1 of the antenna 2 'is shortened regardless of whether the management object is an acrylic plate or a stainless steel plate.

(Example 5)
From now on, the wireless IC tag 1 ′ (example) and the tag (comparative example) in which the second conductor layer 6 is not attached to the wireless IC tag 1 ′ are the same as the case 32 shown in the third modification. And measured the communication distance. Table 4 shows the measurement results. The material and dimensions of the case are as follows. Further, Comparative Example 10 in Table 4 is a result in a free space when not housed in a case, and is the same as Comparative Example 10 in Table 1.
Material: PC resin Dimensions: Length 119mm x Width 32mm x Height 6mm

  From the measurement results, the communication distance was reduced when the second conductor layer 6 was not provided, but the communication distance was hardly reduced when the second conductor layer 6 was provided. Therefore, it has been found that the second conductor layer can suppress a decrease in communication performance even when the wireless IC tag is housed in the case.

(effect)
(Effect 1)
Hereinafter, effects of the wireless IC tag of the present invention will be described. In the wireless IC tag of the present invention, the first hole defined by the first conductor layer and the IC chip is formed on the opposite side of the antenna across the insulating layer as viewed from the direction orthogonal to the main surface of the antenna. A second conductor layer composed of one or a plurality of layers is provided so as to overlap a part of the first conductor layer. Furthermore, the circumference of the second hole defined by the first conductor layer, the second conductor layer, and the IC chip is shorter than the circumference of the first hole. Therefore, the reactance of the antenna of the wireless IC tag can be readjusted, and the resonance state is improved. As a result, it is possible to suppress a decrease in communication performance of the wireless IC tag due to the influence of the article to be attached.

  In addition, since the present invention can be implemented by attaching the second conductor layer to a general-purpose wireless IC tag, a wireless IC tag capable of long-distance communication easily and at low cost can be realized. Furthermore, in order to improve the strength of the wireless IC tag, sufficient communication performance can be obtained even when the wireless IC tag is covered with a cover made of resin or rubber or when the wireless IC tag is housed in a case. it can.

(Effect 2)
In addition, a member or a dielectric layer formed so as to have a gap on the opposite side is provided on the opposite side of the antenna across either one of the insulating layers. Therefore, by fixing the member side or the dielectric layer side of the wireless IC tag to an article or the like, the air gap or the dielectric layer can suppress the influence of the article, and the communication performance of the wireless IC tag can be further prevented from being lowered. As a result, sufficient communication performance can be obtained even when the wireless IC tag is attached to an article such as metal that has a significant decrease in communication performance.

(Effect 3)
Further, a ground layer (third conductor layer) is provided on the opposite side of the antenna with the member or the dielectric layer interposed therebetween. Therefore, when a wireless IC tag is attached to a high dielectric material such as water or ceramic, the ground layer shields the influence of an object on the back surface, and therefore, a wireless IC tag that suppresses deterioration in communication performance due to an article to which the tag is attached is provided. Can do.

(Effect 4)
The second conductor layer is provided on the opposite side of the antenna with either one of the insulating layers sandwiched therebetween and on the opposite side of the antenna with the other sandwiched therebetween, and each of the second conductor layers has one or more layers. Consists of. Thus, the second conductor layer can be installed at a plurality of locations, or can be laminated. Therefore, the reactance of the antenna can be readjusted by appropriately manipulating the second conductor layer having the same shape (installed at a plurality of locations, overlapping, etc.). As a result, it is not necessary to prepare second conductor layers having different sizes depending on the size of the article or antenna. Furthermore, by providing a plurality of second conductor layers, it is possible to make additional adjustments such as by use. For example, the adjustment is performed with the first second conductor layer, and additional adjustment can be easily performed depending on the case where the performance is not sufficient or the type of the article.

(Effect 5)
The wireless IC tag further includes a coating layer that covers the entire circumference of the insulating layer. Therefore, it is possible to improve the strength of the wireless IC tag while suppressing a decrease in communication performance.

(Effect 6)
The wireless IC tag according to claim 1, further comprising a case that houses at least the antenna, the IC chip, the insulating layer, and the second conductor layer.

(Effect 7)
The width of the antenna is not less than 2.5% of the wavelength of the radio wave used for communication and not more than the length of the antenna. In addition, according to the present invention, when the wireless IC tag is installed on a conductor such as metal, the amount of radiation to the space can be increased by increasing the width of the first conductor layer. Can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

101, 201, 301, 401, 501 Wireless IC tag 2 Antenna 2a Main surface 3 Insulating layer 4 IC chip 5a, 5b Adhesive layer 6 Second conductor layer 7 Spacer (dielectric layer)
7a Hollow body (member)
7b Gap 8 Protective sheet 9 Third conductor layer 11 First conductor layer 12 Opening 21 Hole (first hole)
22 holes (second hole)
31 Cover layer 32 Case

Claims (7)

An antenna composed of a first conductor layer and an opening formed in the first conductor layer;
An IC chip disposed in the first conductor layer so as to divide the opening as viewed from a direction orthogonal to the main surface of the antenna;
An insulating layer covering both surfaces of the first conductor layer and the IC chip;
In a wireless IC tag comprising:
On the opposite side of the antenna across the insulating layer,
When viewed from a direction perpendicular to the main surface of the antenna, from the overlapping part of the first hole defined by the first conductive layer and the IC chip is installed in several places multiple, one or more layers A second conductor layer is provided,
A wireless IC tag characterized in that a circumference of a second hole defined by the first conductor layer, the second conductor layer, and the IC chip is shorter than a circumference of the first hole. .   The wireless IC tag according to claim 1, wherein a member or a dielectric layer formed so as to have a gap on the opposite side is provided on the opposite side of the antenna with either one of the insulating layers interposed therebetween. .   The wireless IC tag according to claim 2, wherein a third conductor layer is provided on the opposite side of the antenna across the member or the dielectric layer.   The second conductor layer is provided on the opposite side of the antenna with either one of the insulating layers sandwiched therebetween and on the opposite side of the antenna with the other sandwiched therebetween. The wireless IC tag according to any one of claims 1 to 3, comprising the following layers.   The wireless IC tag according to claim 1, further comprising a coating layer that covers the entire circumference of the insulating layer.   The wireless IC tag according to any one of claims 1 to 4, further comprising a case that houses at least the antenna, the IC chip, the insulating layer, and the second conductor layer.   The wireless IC tag according to claim 1, wherein a width of the antenna is not less than 2.5% of a wavelength of a radio wave used for communication and not more than a length of the antenna.

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