JP3621655B2 - RFID tag structure and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an RFID (Radio Frequency-IDentification) tag structure that performs communication by electromagnetic waves using an antenna coil, and a manufacturing method thereof.
[0002]
[Prior art]
As a communication device using electromagnetic waves, there is an RFID tag having an antenna coil and a control device, which is used for, for example, management of articles.
[0003]
An electromagnetic wave used for communication is composed of an electric field wave and a magnetic field wave of 90 degrees different from each other, and communication is performed using an electromotive force (or current) induced by the magnetic flux constituting this magnetic field component interlinking the antenna coil. I can do it.
[0004]
As for the communication distance by electromagnetic waves, both antenna coils on the transmission side and the reception side need to exist in the region of the magnetic field that maintains the communicable magnetic flux density level. The size of the communicable magnetic field region, that is, the communication distance depends on the power level on the transmitting side. However, if the power is the same, the directivity of the antenna coil in the RFID tag on the receiving side greatly affects.
[0005]
For example, when an RFID tag is attached to a metal surface, an eddy current is generated in the metal by an alternating magnetic field generated by electromagnetic waves for transmitting and receiving the tag. This eddy current generates a magnetic flux that repels the transmission / reception magnetic flux, which attenuates the transmission / reception magnetic flux, making transmission and reception often difficult. Such a material that attenuates the original magnetic flux is hereinafter referred to as “conductive material”.
[0006]
Therefore, when attaching an RFID tag to a member made of a conductive material, a magnetic material is disposed between the RFID tag and the mounting surface of the conductive member, and a magnetic flux is transmitted to the conductive member by passing a transmission / reception magnetic flux therethrough. There are known methods for entering and suppressing the generation of eddy currents.
[0007]
As this magnetic material, a method of efficiently bypassing the magnetic flux even in a thin sheet without increasing the space by using a sheet-like magnetic material such as a sheet-like amorphous magnetic material having a higher magnetic permeability has been proposed. (See JP-A-8-79127).
[0008]
[Problems to be solved by the invention]
In the above-described conventional example, the sheet-like magnetic body is disposed over the entire surface of the transmission / reception antenna coil of the RFID tag. However, as a result of various studies by the present inventors, when a sheet-like magnetic body is arranged on the entire surface of the antenna coil, the transmission / reception sensitivity from the outside with respect to the RFID tag is practical even if it is slightly improved as compared with the case where it is not arranged. It has been found that there is no significant change, and in some cases a closed loop of magnetic flux passing through the sheet-like magnetic material is generated, thereby reducing the sensitivity.
[0009]
The present invention solves the above-described problems, and an object of the present invention is to provide a sheet-like magnetic body having a high magnetic permeability by extending from the magnetic flux generation site formed in the antenna coil of the RFID tag to the outside of the antenna coil. An RFID tag structure that can extend the communicable distance by greatly suppressing the attenuation of magnetic flux by the conductive member even when the RFID tag is attached close to a conductive member such as metal by arranging It is intended to provide a manufacturing method thereof.
[0010]
[Means for Solving the Problems]
Antenna coils used in RFID tags include concentric discs (air-core circular coils) and cylinders in which a conductor is spirally wound around a rod-shaped magnetic core. In any case, a sheet-like magnetic body (hereinafter referred to as a magnetic material) having a high magnetic permeability from one side to the other side of the magnetic flux generation site (a main part that generates a magnetic flux according to Ampere's law when a current is passed through the antenna coil). Except in special cases, simply extending the “sheet-like magnetic body”) suppresses a decrease in sensitivity due to the influence of the conductive member placed close to the RFID tag, and the directionality in that direction is high. It became clear that the communication distance was increased.
[0011]
And the magnetic flux area | region which can communicate in the extension direction expands rather than the case where a sheet-like magnetic body is not extended.
[0012]
For example, in the case of an RFID tag using a concentric disk-shaped antenna coil, a magnetic flux generation site exists in the vicinity of the middle between the center of the antenna coil diameter and the inner periphery of the antenna coil. A relatively high density loop is formed around the conductor of the antenna coil.
[0013]
Note that the magnetic flux generation site is not a point, but exists as a relatively narrow region centered on the center of the diameter of the antenna coil and the midpoint of the inner periphery of the antenna coil. Therefore, when it is desired to increase the directivity outside the specific surface direction (radial direction) in the concentric disk-shaped antenna coil, it is formed in the surface direction from which the magnetic flux is to be increased, for example, a fan shape or a square shape. The sheet-like magnetic body having a high magnetic permeability is arranged to be extended.
[0014]
Then, a considerable part of the magnetic flux from the magnetic flux generation site is guided in the surface direction (radial direction) by the high magnetic permeability sheet-like magnetic body, and as a result, the communicable magnetic flux region on the outer side in the surface direction is expanded. Since the magnetic flux has a spreading characteristic, a magnetic flux region that can be three-dimensionally communicated is expanded around the extended outer side in the plane direction.
[0015]
On the other hand, if the sheet-like magnetic body is simultaneously extended from the magnetic flux generation site to the inside of the antenna coil, for example, in the direction toward the radial center of the antenna coil, the magnetic flux area that can be communicated tends to gradually decrease in proportion to the extension distance. From experiments, it has been found that when the antenna coil is extended to the center of the diameter, it is reduced more than when no sheet-like magnetic body is disposed.
[0016]
Note that it is not preferable to extend the sheet-like magnetic body on both sides of the concentric disk-shaped antenna coil in the plane direction because the effect of the sheet-like magnetic body is canceled out.
[0017]
Therefore, it is preferable that the sheet-like magnetic body arranged in the concentric disk-shaped antenna coil extends to one of the outer sides in the plane direction than the magnetic flux generation site, and at the same time, when the antenna coil extends to the inner side in the radial center direction, a relatively small distance Should be kept on.
[0018]
On the other hand, in the case of an RFID tag having a cylindrical antenna coil, there is a magnetic flux generation site near the tip of the core, and the magnetic flux travels in a loop from the magnetic flux generation site in the axial direction toward the tip on the opposite side. Form.
[0019]
Therefore, when it is desired to increase the directivity on the outside in the axial direction in the cylindrical antenna coil, the sheet-like magnetic body is extended outward in the axial direction from the magnetic flux generation site. Then, a considerable portion of the magnetic flux from the magnetic flux generation site is guided outward in the axial direction by the high magnetic permeability sheet-like magnetic body, and as a result, the communicable magnetic flux region in the axial direction is expanded.
[0020]
In this case as well, the magnetic flux region capable of three-dimensional communication is expanded with the extended axial direction as the center. In addition, since the magnetic flux loop becomes large with this configuration, as a result, a phenomenon occurs in which the communicable magnetic flux region on the outer side in the axial direction from the tip portion on the opposite side is enlarged by substantially the same size.
[0021]
If the sheet-like magnetic body is simultaneously extended from the magnetic flux generation site in the axial center direction, the communicable magnetic flux region gradually decreases, and when it exceeds the axial center point, it rapidly decreases. Therefore, it is preferable that the sheet-like magnetic body arranged in the cylindrical antenna coil extends outward in the axial direction from the magnetic flux generation site, and when extending in the axial center direction at the same time, it should be kept at a relatively short distance.
[0022]
The “high magnetic permeability sheet-like magnetic material” used in the present invention has a magnetic permeability higher than that of iron or a general magnetic core, for example, a high magnetic permeability of 10,000 or more in terms of relative permeability. The relative permeability is a ratio between the magnetic permeability and the vacuum permeability.
[0023]
As such a high magnetic permeability magnetic material, it is preferable to use an amorphous magnetic material formed in a sheet shape. The relative magnetic permeability of the amorphous magnetic material is generally in the range of about 30,000 to 500,000.
[0024]
By using a high magnetic permeability magnetic material, even when the RFID tag is attached close to a conductive member such as metal, the magnetic flux absorbed by the conductive member is effectively guided to the high magnetic permeability magnetic material. Therefore, a decrease in magnetic flux that can be used for communication can be greatly suppressed.
[0025]
A typical example of the high magnetic permeability magnetic material is an amorphous magnetic material, but the price per unit weight of the amorphous magnetic material is very high at present. Therefore, by making the amorphous magnetic material into a sheet shape, the effect of extending the communication distance is high even with a small amount of material, which is extremely advantageous in terms of cost.
[0026]
Further, since it is in the form of a sheet, the increase in weight is extremely small and the weight can be reduced, so that it is preferable even when used in a portable communication device or the like.
[0027]
Moreover, sheet-like magnetic bodies, such as an amorphous magnetic body, can be formed in the sheet | seat which satisfy | fills both flexibility and practical intensity | strength by setting it as the thickness of about 10 micrometers-50 micrometers, for example. When a flexible sheet-like magnetic material is used, it can be easily deformed and integrated with the RFID tag.
[0028]
An RFID tag structure according to the present invention for achieving the above-described object is as follows: Formed in a disk shape In an RFID tag structure having an antenna coil and a control unit and communicating with electromagnetic waves, a sheet-like magnetic body having a high magnetic permeability is the antenna coil. Between the diameter center of the antenna coil and the inner periphery of the antenna coil A first sheet material disposed outside the antenna coil and a second sheet disposed outside the sheet-like magnetic body. The sheet materials are joined to each other.
[0029]
Since the present invention is configured as described above, even when the RFID tag is attached close to a conductive member such as metal, the magnetic flux absorbed by the conductive member is transferred to a sheet-like magnetic body having a high permeability. Since it can guide effectively, the reduction of the magnetic flux which can be utilized for communication can be suppressed significantly. In addition, the communication directivity in a specific direction is increased, thereby increasing the communication distance.
[0030]
Further, since the RFID tag and the sheet-like magnetic body are sandwiched between the first sheet material and the second sheet material and can maintain a stable positional relationship with each other, the directivity thereof is also stabilized.
[0031]
In addition, since the first sheet material and the second sheet material are joined to each other, the RFID tag and the sheet-like magnetic body can be sealed inside, and water resistance, gas resistance, and the like can be imparted.
[0032]
Moreover, it is preferable when the sheet-like magnetic body having the high magnetic permeability is a sheet-like amorphous magnetic body.
[0033]
In addition, the antenna coil is formed in a disk shape, and the high magnetic permeability sheet is formed outside the antenna coil from a magnetism generation site formed in the middle between the radial center of the antenna coil and the inner periphery of the antenna coil. It is preferable when the magnets are extended and arranged.
[0034]
The RFID tag structure manufacturing method according to the present invention includes an antenna coil and a control unit, and the RFID tag structure manufacturing method communicates by electromagnetic waves. In the RFID tag structure manufacturing method, a plurality of RFID tags are arranged along the first elongated sheet material. A plurality of high magnetic permeability sheet-like magnetic bodies are arranged and fixed at predetermined intervals along the elongated second sheet material, and then the RFID tags, the sheet-like magnetic bodies, Are aligned as a pair, and the first sheet material and the second sheet material are joined to each other.
[0035]
According to the above manufacturing method, the above-described RFID tag structure can be manufactured efficiently and inexpensively.
[0036]
In addition, in the case where a division part for separating the RFID tag structures is formed on the first sheet material and the second sheet material joined to each other, individual RFID tag structures can be easily formed by the division parts. Can be separated.
[0037]
Further, the sheet-like magnetic body can be arrayed and fixed by screen printing. .
[0038]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an RFID tag structure and a manufacturing method thereof according to the present invention will be specifically described with reference to the drawings. FIGS. 1A and 1B are a side view and a plan view showing a state in which RFID tags having concentric disk-shaped antenna coils are bonded and fixed to a first sheet material at predetermined intervals, and FIG. , (B) are a side view and a plan view showing a state in which fan-shaped sheet-like magnetic bodies are arranged by being bonded and fixed to a second sheet material at predetermined intervals.
[0039]
FIG. 3 is a side view showing a state in which the first and second sheet materials are superposed while positioning the RFID tag and the sheet-like magnetic body as a pair, and FIGS. 4A and 4B are views showing the RFID tag and They are a side view and a top view which show a mode that a 1st, 2nd sheet material is heated and pressurized and joined around a sheet-like magnetic body.
[0040]
5 (a) and 5 (b), an adhesive layer and a release layer are sequentially laminated on the back surface of the joined first sheet material, and a dividing portion such as a straight perforation is provided at the boundary portion of each RFID tag structure. It is the side view and top view which show the mode.
[0041]
FIG. 6A is a plan view showing a state in which a divided portion such as a circular perforation is provided outside the joint boundary line of each RFID tag, and FIG. 6B is a view along the divided portion such as a circular perforation. It is a top view which shows a mode that the RFID tag structure was cut away.
[0042]
FIG. 7A is a plan view showing a configuration of an RFID tag having a concentric disk-shaped antenna coil, and FIG. 7B is a side view showing a state of a magnetic field generated in the RFID tag having a concentric disk-shaped antenna coil. FIG. 8 is a block diagram showing the configuration of the RFID tag control system.
[0043]
FIG. 9 is a diagram showing electric field characteristics due to magnetic flux generated by a concentric disk-shaped antenna coil, and shows a comparison between the case where there is a sheet-like magnetic body and the case where there is no sheet-like magnetic body, and FIG. It is a schematic diagram which shows the magnetic flux area | region (communication possible maximum distance) of a coil surface direction.
[0044]
FIGS. 11A and 11B are a side view and a plan view showing a state in which a plurality of RFID tags having a cylindrical antenna coil are bonded and fixed to a first sheet material at a predetermined interval, and FIG. (B) and (b) are a side view and a plan view showing a state in which rectangular sheet-like magnetic bodies are arranged by being bonded and fixed to a second sheet material at a predetermined interval.
[0045]
FIG. 13A shows an adhesive layer and a release layer on the back surface of the first sheet material joined by heating and pressurizing the first and second sheet materials around the RFID tag and the sheet-like magnetic body. FIG. 13B is a side view showing a state in which a layered portion such as a straight perforation is provided at the boundary portion of each RFID tag structure, and FIG. 13B shows the RFID tag structure along the divided portion such as a perforation. It is a top view which shows a mode that it cut | disconnected.
[0046]
FIG. 14 is a diagram showing a configuration of an RFID tag having a cylindrical antenna coil and a state of a magnetic field generated in the antenna coil.
[0047]
Figure 15 As a reference example FIG. 16 is a schematic diagram showing a communicable magnetic flux region (maximum communicable distance) in the antenna coil axis direction in the RFID tag structure shown in FIG. 15. FIG.
[0048]
First, with reference to FIG. 1 to FIG. 10, a configuration in the case where an RFID tag 1a having a concentric disk-shaped antenna coil 2a is adopted as an example of an RFID tag structure will be described. The RFID tags 1a and 1b suitably employed in the present embodiment are electromagnetic coupling type and electromagnetic induction type RFID tags. In the present embodiment, an embodiment in which an electromagnetic induction type RFID tag is used will be described below. Explained.
[0049]
The RFID tag 1a shown in FIGS. 1 to 7 is an example of an RFID tag structure that performs communication with electromagnetic waves using an antenna coil 2a. As shown in FIG. 7A, a concentric disk-like antenna coil 2a is used. The semiconductor IC chip 4 serving as a control unit is directly connected without using a printed circuit board or the like, thereby realizing the downsizing of the RFID tag 1a.
[0050]
The semiconductor IC chip 4 is configured by integrally packaging an IC (semiconductor integrated circuit) chip, an LSI (semiconductor large-scale integrated circuit) chip, or the like. As shown, a CPU 4a serving as a control unit, a memory 4b serving as a storage unit, a transceiver 4c, and a capacitor 4d serving as a power storage unit are provided.
[0051]
A signal transmitted from an external read / write terminal (not shown) or the like is transmitted to the CPU 4a via the transceiver 4c, and the electric power is stored in the capacitor 4d. Note that there may be no capacitor 4d serving as a power storage means, and power may be continuously supplied to the semiconductor IC chip 4 from an external read / write terminal or the like.
[0052]
The CPU 4a is a central processing unit, and reads programs and various data stored in the memory 4b, performs necessary calculations and determinations, and performs various controls.
[0053]
The memory 4b stores various programs for the operation of the CPU 4a and various unique information of articles on which the electromagnetic induction tag 1a is installed.
[0054]
Further, as an example of the concentric disk-shaped antenna coil 2a shown in FIG. 7, a copper wire having a diameter of about 30 μm is wound in a concentric disk shape with multiple layers in the radial direction by single wire winding, and the antenna coil 2a The inductance was about 9.5 mH (frequency 125 kHz), and the capacitance of a capacitor separately connected to the antenna coil 2a for resonance was about 170 pF (frequency 125 kHz).
[0055]
The RFID tag 1a of the present embodiment uses a radio communication system of amplitude shift keying (ASK) with a radio frequency of one wave, has a wide resonance frequency band, and a hollow antenna coil with a wire diameter of several tens of microns. The RFID tag 1a using a CMOS-IC with very little power consumption and incorporating a special transmission / reception circuit 2a is adopted.
[0056]
Conventionally, electromagnetic induction type and electromagnetic coupling type RFID tags enable power reception and signal transmission / reception by changes in the magnetic field penetrating through an antenna coil embedded in the RFID tag. If there is a conductive material such as a magnetic material or metal that affects communication by generating eddy current due to the magnetic field generated during tag communication or power transfer, the magnetic field is attenuated due to the influence of the conductive member. Because there is a fixed idea that it is impossible to do so, it is common sense to exclude magnetic materials and metal articles from the vicinity of the RFID tag, and no attempt has been made to attach the RFID tag to a metal container or metal article.
[0057]
Therefore, the present inventors, for the purpose of effective use of the RFID tag to a conductive member such as a metal or a magnetic material, if a conductive member exists near the place where the RFID tag is installed, the magnetic field is affected by the influence of the conductive member. As a result of intensive research and experiments to solve this problem based on the technical background that the tape is attenuated and cannot be used, a sheet-like magnetic body having high permeability can be obtained even if the RFID tag is attached to a conductive member. It is found that electromagnetic waves can be effectively communicated with the outside by effectively inducing magnetic flux if it is arranged so as to extend outside the antenna coil from the magnetic flux generation site formed in the antenna coil of the RFID tag. The effective use of the RFID tag with respect to the sex member is realized.
[0058]
The RFID tag receives an alternating magnetic field transmitted from an external read / write terminal or the like at the resonance frequency of an antenna coil built in the RFID tag. At that time, the conventional RFID tag uses frequency shift keying (FSK) to increase the communication distance, and the radio frequency uses, for example, two waves of 125 kHz and 117 kHz, and the received power is increased. For this reason, a method of extending the communication distance by using a ferrite core for the antenna coil and increasing the coil diameter to make a plurality of windings has been common.
[0059]
In the frequency shift keying (FSK) method using two radio frequencies, when a conductive member such as a metal or magnetic material approaches, the reception frequency shifts and the received power decreases and a communication error occurs and communication becomes impossible. Because the distance is extremely reduced and it becomes practically unusable, the fixed idea that RFID tags cannot be used attached to conductive members such as metals and magnetic materials was dominant. .
[0060]
Recently, however, the radio frequency uses a single-wave amplitude shift keying (ASK) radio communication system, and is a consumption that incorporates a special transmission / reception circuit with an air-core antenna coil having a wide resonance frequency band and a wire diameter of several tens of microns. An RFID tag using a CMOS-IC with very little power has been proposed.
[0061]
This RFID tag uses an amplitude shift keying (ASK) wireless communication system even when a conductive member such as a metal or magnetic material is nearby, and has a wider resonance frequency band than FSK. The results of experiments conducted by the present inventors have revealed that the power does not decrease and the wireless communication is hardly affected.
[0062]
In the RFID tag structure according to the present invention, an amorphous magnetic sheet 5 which is a sheet-like magnetic body having a high magnetic permeability is arranged in parallel to one surface of the antenna coil 2a in the RFID tag 1a. At this time, the amorphous magnetic material sheet 5 is disposed so as to extend from the magnetic flux generating portion of the antenna coil 2a to the outside of the antenna coil 2a, and the first sheet material 6 is further provided on the front surface side of the RFID tag 1a, so A second sheet material 7 is provided on the surface side of the body sheet 5, and the first and second sheet materials 6 and 7 are joined to each other.
[0063]
In the RFID tag structure manufacturing method according to the present invention, first, a plurality of RFID tags 1 a are arranged and fixed at predetermined intervals along the first elongated sheet material 6, and then along the second elongated sheet material 7. A plurality of amorphous magnetic sheets 5 that are sheet-like magnetic bodies are arranged and fixed at predetermined intervals.
[0064]
Next, each RFID tag 1a and each amorphous magnetic material sheet 5 are aligned as a pair, and the first and second sheet materials 6 and 7 are joined to each other by thermocompression bonding or the like.
[0065]
FIG. 1 shows a state in which a plurality of RFID tags 1a having concentric disc-shaped antenna coils 2a are arranged and fixed at predetermined intervals on a first elongated sheet material 6 by an adhesive 8 or the like, while FIG. 2 shows a high magnetic permeability. A sheet-like amorphous magnetic sheet 5 to be a sheet-like magnetic body is formed in a fan shape, and a plurality of the amorphous magnetic sheets 5 are arranged and fixed to the second long and thin sheet material 7 with an adhesive 8 or the like at a predetermined interval. Show.
[0066]
Here, the amorphous magnetic material sheet 5 is obtained by forming an amorphous alloy into a sheet shape, and this amorphous alloy is generally formed into a tough foil body by a super rapid cooling method. The characteristics of the amorphous magnetic sheet 5 are high permeability, low coercivity, low iron loss, low hysteresis loss, low eddy current loss, magnetostriction can be controlled over a wide range, high electrical resistivity and low temperature change. The thermal expansion coefficient and the temperature coefficient of rigidity are small.
[0067]
Further, this amorphous alloy can be formed in a flake shape. The amorphous alloy formed in the flake shape is formed in a sheet shape, for example, an amoric sheet (trade name) manufactured by Riken Corporation.
[0068]
That is, this amoric sheet is a sheet in which cocoon leaf flakes of high permeability cobalt amorphous alloy are uniformly dispersed in an insulating film and fixed in a sandwich shape.
[0069]
Alternatively, a magnetic protective sheet constituted by forming a flaky amorphous magnetic material into a sheet shape in a state where it is dispersed may be used.
[0070]
The amorphous magnetic sheet 5 may be formed by kneading a fine powder of an amorphous alloy in a resin binder at a high concentration and forming it directly on the second sheet material 7 by screen printing or the like. Since the agent 8 or the like is unnecessary, the production is easy.
[0071]
As the first and second sheet materials 6 and 7, for example, a flexible resin sheet material made of polyethylene, polypropylene, polyamide vinyl chloride resin, or a copolymer thereof can be used. The sheets can be welded and joined to each other by pressure treatment, and are made of a transparent, translucent or opaque sheet material.
[0072]
In particular, by making the second sheet material 7 transparent or translucent, the amorphous magnetic sheet 5 can be visually recognized from the outside, so that the direction of directivity can be easily determined, and installation and construction are facilitated.
[0073]
Then, the elongated first sheet material 6 in which the plurality of RFID tags 1a are fixedly arranged and the elongated second sheet material 7 in which the plurality of amorphous magnetic sheets 5 are fixedly arranged are wound in rolls, respectively. It is possible to align them while facing each other while feeding them out and sequentially join them by thermal welding.
[0074]
FIG. 3 shows the first and second sheets while positioning the RFID tag 1a fixed to the first sheet material 6 and the amorphous magnetic sheet 5 fixed to the second sheet material 7 as a pair. A mode that the materials 6 and 7 are piled up is shown.
[0075]
The alignment between the RFID tag 1a and the amorphous magnetic material sheet 5 is described in detail with reference to FIG. ₁ The amorphous magnetic sheet 5 is disposed so as to extend from the magnetic flux generation site A formed in the middle of the inner peripheral portion 2a1 of the antenna coil 2a toward the outside of the antenna coil 2a.
[0076]
As shown in FIGS. 2 and 10, the amorphous magnetic sheet 5 is formed in a fan shape, and is arranged to extend from the magnetic flux generation site A to the outside of the antenna coil 2a. The sector angle θ is preferably about 90 degrees, and a practically preferable range is 60 degrees to 180 degrees.
[0077]
Thereafter, as shown in FIG. 4, first and second sheet materials 6 disposed around the RFID tag 1 a and the amorphous magnetic sheet 5 and outside the RFID tag 1 a and the amorphous magnetic sheet 5, respectively. 7 is heated and pressurized to bond (laminate) the first and second sheet materials 6 and 7 together.
[0078]
In FIG. 4, C is a joint portion, and as shown in FIG. 4B, the periphery of the RFID tag 1a and the amorphous magnetic sheet 5 is a laminate in which the outside of the joint portion C indicated by a two-dot chain line in the figure is laminated. Part. Thus, if it joins a little apart from the circumference | surroundings of the RFID tag 1a, it can avoid that the RFID tag 1a is damaged by heat.
[0079]
And after joining the 1st, 2nd sheet | seat materials 6 and 7, as shown in FIG. 5, the adhesive bond layer 9 and the release layer 10 were laminated | stacked sequentially on the back surface side of the 1st sheet | seat material 6, A dividing portion 11 such as a perforation is formed in the first and second sheet materials 6 and 7 at the boundary portion of each RFID tag structure.
[0080]
When separating each RFID tag structure, each RFID tag structure can be easily separated by separating from the dividing section 11, and when attaching the RFID tag structure to an article, the release layer 10 such as paper is peeled off and bonded. The adhesive layer 9 is exposed, and the adhesive layer 9 can be used to stick the product to the article for easy installation.
[0081]
FIG. 6A shows a state in which a circular divided portion 11 indicated by a dotted line is formed outside the circular joint C indicated by a two-dot chain line, and FIG. A state in which the RFID tag structure is separated along the dividing unit 11 is shown.
[0082]
FIG. 9 shows the measurement of electric field characteristics (magnetic flux density characteristics) induced in each part of the RFID tag 1a when an electromagnetic wave (magnetic flux) is applied from the outside to the RFID tag 1a having the concentric disk-shaped antenna coil 2a. A curve a indicated by a solid line 9 is an electric field characteristic when the amorphous magnetic sheet 5 is not disposed, and a curve b indicated by a broken line is an electric field characteristic when the amorphous magnetic sheet 5 is disposed.
[0083]
In the curve b, the diameter center o of the antenna coil 2a is shown. ₁ 9 is the case where the amorphous magnetic sheet 5 is arranged on the left side of the antenna coil 2a, and the right side of FIG. 9 is a comprehensive case where the amorphous magnetic sheet 5 is arranged on the right side of the antenna coil 2a. The electric field characteristics are shown for convenience. Actually, either the left or right curve b in FIG. 9 appears.
[0084]
In the curve b shown in FIG. 9, when the amorphous magnetic material sheet 5 is arranged to extend from the magnetic flux generation site A of the antenna coil 2a to the outside of the antenna coil 2a, the peak value of the electric field characteristic becomes high and the sensitivity becomes high. It shows that.
[0085]
In the concentric disk-shaped antenna coil 2a, the diameter center o ₁ And the inner peripheral portion 2a1 of the antenna coil 2a have a magnetic flux generation site A where the peak value of the electric field characteristic appears, and the amorphous magnetic sheet 5 extends from the magnetic flux generation site A to the outside of the antenna coil 2a. Arranged.
[0086]
Note that, as shown by curves a and b in FIG. 9, the magnetic flux generation site A does not move regardless of the presence or absence of the amorphous magnetic sheet 5.
[0087]
The electric field characteristic measuring apparatus has a concentric disk-shaped antenna coil 2a of the World Disk Tag series made by Sokymat on the measurement stage, and an SSG oscillator (KENWOOD FG-273) at both ends of the antenna coil 2a. Ser. 7020087) was electrically connected to give a sine wave output with a frequency of 125 kHz and 12 Vpp (the voltage amplitude value from peak to peak is 12 V).
[0088]
A pickup coil is employed as means for measuring the electric field strength generated around the antenna coil 2a. The pick-up coil was tuned to 125 kHz with a 1 mH open magnetic inductor and a 1591 pF tuning ceramic capacitor.
[0089]
The probe of an oscilloscope (SONY-Tektronix TDS34OAP Ser. J300635) is electrically connected to both ends of the pickup coil, and the pickup coil is connected to the antenna coil 2a along the XY plane and the XZ plane on the measurement stage. Center of diameter o ₁ The voltage amplitude value from the peak to the peak of the voltage value induced in the pickup coil was measured by plotting every 5 mm on the concentric circle.
[0090]
FIG. 9 shows measured electric field characteristics for each position in the RFID tag 1a having the concentric disk-shaped antenna coil 2a. The electric field is measured at a peak voltage, and the electric field is proportional to the magnetic flux generated in the portion. The diameter center o of the coil 2a ₁ And a magnetic flux generation site A exists at an intermediate point between the inner peripheral portion 2a1 of the antenna coil 2a.
[0091]
In FIG. 10, the first and second sheet materials 6 are formed by aligning the sector-shaped amorphous magnetic sheet 5 and the RFID tag 1a having the concentric disk-shaped antenna coil 2a on a stainless steel plate which is a conductive material (not shown). , 7 are placed on the RFID tag structure, and the communicable magnetic flux region (maximum communicable distance L) in the surface direction of the antenna coil 2a (the left-right direction in FIG. _max ).
[0092]
In FIG. 10, the outer diameter of the concentric disc-shaped antenna coil 2a is 25 mm, the inner diameter is 20 mm, the fan-shaped outer diameter of the amorphous magnetic sheet 5 is 80 mm, the inner diameter is 10 mm, the amorphous magnetic body The thickness of the sheet 5 was 30 μm, and an amorphous magnetic sheet manufactured by Allied Signal of the United States based on the Fe—Ni—Mo—B—S system having a maximum magnetic permeability μ of 800000 was adopted.
[0093]
In FIG. 10, a magnetic flux region B that can be communicated appears outside the amorphous magnetic sheet 5 and approximates the fan-shaped outer shape, and the diameter center o of the antenna coil 2a appears. ₁ The maximum distance L that can be communicated on the extension line in the direction of the amorphous magnetic sheet 5 _max Maximum point B ₁ Appears.
[0094]
When there is no amorphous magnetic material sheet 5 or when the amorphous magnetic material sheet 5 is disposed on the entire surface of the antenna coil 2a, it extends from the magnetic flux generation site A formed on the antenna coil 2a to the outside of the antenna coil 2a to form amorphous magnetism. When the body sheet 5 is arranged, the maximum communicable distance L _max It becomes clear from the experimental results that becomes larger.
[0095]
Also, the fan-shaped angle θ of the amorphous magnetic sheet 5 is optimally 90 degrees, and when the angle θ is in the range of 60 degrees to 180 degrees, the amorphous magnetic sheet 5 is not present, or the entire surface of the antenna coil 2a is amorphous magnetic. The maximum communicable distance L is greater when the amorphous magnetic sheet 5 is disposed extending from the magnetic flux generation site A formed in the antenna coil 2a to the outside of the antenna coil 2a than when the body sheet 5 is disposed. _max It becomes clear from the experimental results that becomes larger.
[0096]
In addition, when the antenna coil 2a is placed on a conductive material such as a stainless steel plate, an aluminum plate, or a copper plate via the amorphous magnetic sheet 5 as described above, communication is possible more than when there is no conductive material. Distance L _max It becomes clear from the experimental results that becomes larger.
[0097]
In addition, the shape of the amorphous magnetic material sheet 5 having a high magnetic permeability can be a rectangular shape or various other shapes besides a sector shape.
[0098]
Next, using FIG. 11 to FIG. Reference example The configuration when the RFID tag 1b having the cylindrical antenna coil 2b is employed will be described. In addition, what was comprised similarly to the said embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.
[0099]
FIG. 11 shows a state in which a plurality of RFID tags 1b having a cylindrical antenna coil 2b are arranged on the first sheet material 6 at predetermined intervals and fixed with an adhesive 8 or the like, and FIG. 12 corresponds to the RFID tag 1b. A state in which a plurality of amorphous magnetic sheets 5 having a shape to be arranged is arranged on the second sheet material 7 at a predetermined interval and fixed with an adhesive 8 or the like is shown.
[0100]
FIG. 13 shows a state where a first sheet material 6 in which RFID tags 1b having a plurality of cylindrical antenna coils 2b are arranged and fixed and a second sheet material 7 in which a plurality of amorphous magnetic sheets 5 are arranged and fixed are joined. Indicates.
[0101]
In the RFID tag 1b having the antenna coil 2b formed in a cylinder shape, as shown in FIG. 15, the antenna from the magnetic flux generation site A formed at the end portion in the axial direction (left-right direction in FIG. 15) of the antenna coil 2b. The first and second sheet materials 6 and 7 are joined so that the amorphous magnetic material sheet 5 serving as a high magnetic permeability sheet-like magnetic material is extended toward the outside of the coil 2b.
[0102]
Then, after the first and second sheet materials 6 and 7 are joined, the adhesive layer 9 and the release layer 10 are sequentially laminated on the back surface side of the first sheet material 6 as shown in FIG. Then, a split portion 11 such as a perforation is formed in the first and second sheet materials 6 and 7 at the boundary portion of each RFID tag structure. FIG. 13B shows an RFID tag structure cut out from the dividing section 11.
[0103]
As shown in FIG. 14, a cylindrical core member 3 such as an iron core or ferrite is inserted in the axial direction (left-right direction in FIG. 14) inside an antenna coil 2b formed in a cylindrical shape by winding a single wire.
[0104]
For example, as an example of the antenna coil 2b, a state in which a copper wire having a diameter of about 30 μm is wound in a single-winding wire in a radial direction with multiple layers in a cylindrical shape in the axial direction and the core member 3 is inside the antenna coil 2b. In this case, the inductance was about 9.5 mH (frequency 125 kHz), and the capacitance of the capacitor separately connected to the antenna coil 2a for resonance was about 170 pF (frequency 125 kHz).
[0105]
FIG. 15 shows electric field characteristics for each position in the RFID tag 1b having the cylindrical antenna coil 2b. As shown in FIG. 15, the center o of the antenna coil 2b ₂ Becomes the minimum point of the electric field characteristic due to the magnetic flux, and both ends of the antenna coil 2b become the maximum point of the electric field characteristic.
[0106]
FIG. 16 shows the communicable magnetic flux region B (maximum communicable distance L) of the antenna coil 2b in the RFID tag 1b shown in FIG. _max ) Shows the experimental results. The amorphous magnetic sheet 5 is an amorphous magnetic sheet manufactured by Allied Signal, Inc. of the United States based on Fe-Ni-Mo-BS system having a thickness of 30 μm and a maximum magnetic permeability μ of 800,000. In this case, the antenna coil 2b is disposed so as to extend from the magnetic flux generation site A formed at both ends of the antenna coil 2b to the outside of the antenna coil 2b.
[0107]
This reference example The RFID tag structure is the maximum distance L that can be communicated in a state where it is arranged on a stainless steel plate. _max Is measured. As shown in FIG. 16, the communicable magnetic flux region B is formed in a bowl shape along the axial direction of the antenna coil 2b, and on the side where the amorphous magnetic sheet 5 is arranged on the extension line in the axial direction of the antenna coil 2b. Maximum communication distance L _max Maximum point B ₁ Appears.
[0108]
In addition, as a conductive material that affects the communication by generating an eddy current due to the magnetic field H generated when the RFID tags 1a and 1b communicate and carry power, an eddy current is generated to attenuate the original magnetic flux. In addition to the above-mentioned stainless steel plate, copper plate, aluminum plate, iron, cobalt, nickel, and alloys thereof, ferromagnetic metals such as ferrite, or paramagnetic metals such as aluminum, copper and chrome, A conductive plastic or the like is applicable.
[0109]
【The invention's effect】
Since the present invention has the above-described configuration and operation, a structure in which a sheet-like magnetic body having a high magnetic permeability is disposed extending from the magnetic flux generation site formed in the antenna coil of the RFID tag to the outside of the antenna coil, and As a result, even when the RFID tag is attached close to a conductive member such as metal, the attenuation of magnetic flux by the conductive member can be significantly suppressed, and the communicable distance can be extended.
[0110]
That is, according to the RFID tag structure of the first aspect, even when the RFID tag is attached close to a conductive member such as metal, the magnetic flux absorbed by the conductive member Therefore, the decrease in magnetic flux that can be used for communication can be greatly suppressed. In addition, the communication directivity in a specific direction is increased, thereby increasing the communication distance.
[0111]
Further, since the RFID tag and the sheet-like magnetic body are sandwiched between the first sheet material and the second sheet material and can maintain a stable positional relationship with each other, the directivity thereof is also stabilized.
[0112]
In addition, since the first sheet material and the second sheet material are joined to each other, the RFID tag and the sheet-like magnetic body can be sealed inside, and water resistance, gas resistance, and the like can be imparted.
[0113]
Further, according to the RFID tag structure manufacturing method of the present invention, the above-described RFID tag structure can be manufactured efficiently and inexpensively.
[0114]
In addition, in the case where a divided portion that separates the RFID tag structures is formed in the first sheet material and the second sheet material that are joined to each other, the individual RFID tag structures are easily separated by the divided portions. I can do it.
[Brief description of the drawings]
FIGS. 1A and 1B are a side view and a plan view showing a state in which RFID tags having concentric disc-shaped antenna coils are bonded and fixed to a first sheet material at predetermined intervals.
FIGS. 2A and 2B are a side view and a plan view showing a state in which fan-shaped sheet-like magnetic bodies are arranged by being bonded and fixed to a second sheet material at predetermined intervals.
FIG. 3 is a side view showing a state in which the first and second sheet materials are superposed while positioning the RFID tag and the sheet-like magnetic body as a pair, respectively.
FIGS. 4A and 4B are a side view and a plan view showing a state in which the first and second sheet materials are joined by heating and pressurizing around the RFID tag and the sheet-like magnetic body. FIGS. .
FIGS. 5A and 5B are an adhesive layer and a release layer sequentially laminated on the back surface of the bonded first sheet material, and a dividing portion such as a straight perforation at a boundary portion of each RFID tag structure; It is the side view and top view which show a mode that was provided.
6A is a plan view showing a state in which a divided portion such as a circular perforation is provided outside the bonding boundary line of each RFID tag, and FIG. 6B is a view along the divided portion such as a circular perforation. It is a top view which shows a mode that the RFID tag structure was cut away.
7A is a plan view showing a configuration of an RFID tag having a concentric disk-shaped antenna coil, and FIG. 7B is a side view showing a state of a magnetic field generated in the RFID tag having a concentric disk-shaped antenna coil. is there.
FIG. 8 is a block diagram showing a configuration of a control system of the RFID tag.
FIG. 9 is a diagram showing electric field characteristics due to magnetic flux generated by a concentric disk-shaped antenna coil, and a comparison between the case where there is a sheet-like magnetic body and the case where there is no sheet-like magnetic body.
FIG. 10 is a schematic diagram showing a communicable magnetic flux region (maximum communicable distance) in the antenna coil surface direction in an RFID tag having concentric disk-shaped antenna coils.
FIGS. 11A and 11B are a side view and a plan view showing a state in which a plurality of RFID tags having a cylindrical antenna coil are bonded and fixed to a first sheet material at a predetermined interval.
FIGS. 12A and 12B are a side view and a plan view showing a state in which square-shaped sheet-like magnetic bodies are arranged by being bonded and fixed to a second sheet material at a predetermined interval.
FIG. 13A shows an adhesive layer and a release layer on the back surface of the first sheet material joined by heating and pressurizing the first and second sheet materials around the RFID tag and the sheet-like magnetic body. It is a side view which shows a mode that the layer was laminated | stacked one by one and the division | segmentation part of a straight perforation etc. was provided in the boundary part of each RFID tag structure, (b) is a RFID tag structure along a division part, such as a perforation. It is a top view which shows a mode that it cut | disconnected.
FIG. 14 is a diagram illustrating a configuration of an RFID tag having a cylindrical antenna coil and a state of a magnetic field generated in the antenna coil.
[Figure 15] As a reference example It is a figure which shows the electric field characteristic by the magnetic flux which generate | occur | produces with the cylindrical antenna coil of a RFID tag structure.
16 is a schematic diagram showing a communicable magnetic flux region (maximum communicable distance) in the antenna coil axis direction in the RFID tag structure shown in FIG.
[Explanation of symbols]
1a, 1b ... RFID tag
2a, 2b ... Antenna coil
2a1 ... Inner circumference
3. Core member
4 ... Semiconductor IC chip
4a ... CPU
4b ... Memory
4c ... transceiver
4d: Capacitor
5 ... Amorphous magnetic sheet
6, 7 ... 1st, 2nd sheet material
8 ... Adhesive
9 ... Adhesive layer
10 ... Release layer
11: Dividing part
A ... Magnetic flux generation part
B ... Communication magnetic flux area
B ₁ ... Maximum point
C ... Junction
H ... Magnetic field
L _max ... Maximum communication distance
o ₁ ... diameter center
o ₂ …center
θ: sector angle

Claims (5)

In an RFID tag structure having an antenna coil and a control unit formed in a disk shape and communicating with electromagnetic waves,
A sheet-like magnetic body having a high magnetic permeability is arranged so as to extend from the magnetic flux generation site formed between the radial center of the antenna coil and the inner periphery of the antenna coil to the outside of the antenna coil, An RFID tag structure, wherein a first sheet material disposed outside an antenna coil and a second sheet material disposed outside the sheet-like magnetic body are joined to each other. 2. The RFID tag structure according to claim 1, wherein the sheet-like magnetic body having a high magnetic permeability is a sheet-like amorphous magnetic body. In a manufacturing method of an RFID tag structure having an antenna coil and a control unit and communicating with electromagnetic waves,
A plurality of RFID tags are arranged and fixed at predetermined intervals along the first elongated sheet material, and a plurality of high magnetic permeability sheet-like magnetic bodies are arranged and fixed at predetermined intervals along the second elongated sheet material. Each RFID tag and each sheet-like magnetic body are aligned as a pair, and the first sheet material and the second sheet material are joined to each other. Method. The RFID tag structure manufacturing method according to claim 3 , wherein a divided portion for separating the RFID tag structures is formed in the first sheet material and the second sheet material joined to each other. . 5. The method of manufacturing an RFID tag structure according to claim 3, wherein the sheet-like magnetic bodies are arranged and fixed by screen printing .

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