JP2011048794A - Rfid inlet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID inlet for suppressing the malfunction of a TFT circuit due to a magnetic field caused by an antenna pattern. <P>SOLUTION: An RFID inlet 10 includes: a substrate 2; a plane spiral-shaped antenna pattern 3 formed on the surface of the substrate 2; and a TFT circuit 4 formed on the surface of the substrate 2, and connected to the antenna pattern 3. The TFT circuit 4 includes a high integration part 4a including circuit elements; and a low integration part 4b excluding any circuit element, and including wiring for interconnecting the circuit elements in the high integration part 4a. The high integration part 4a is arranged in a region which is not overlapped with the antenna pattern 3 when it is viewed from the normal direction of the substrate 2 in the surface of the substrate 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RFID (Radio Frequency IDentification) inlet, and more particularly to an RFID inlet using an IC using a TFT.

  Conventionally, as a circuit constituting an inlet of an RFID tag or a non-contact type IC card (RFID inlet), as described in Patent Document 1, for example, an IC chip manufactured using a semiconductor substrate has been used. It was. However, in recent years, a method of forming an IC using a TFT (Thin Film Transistor) on an antenna substrate has been studied. An IC using a TFT is called a TFT circuit.

JP 2007-140904 A

  By the way, the TFT circuit studied so far is arranged at a position overlapping the antenna pattern when viewed from the normal direction of the substrate. However, in this configuration, since the magnetic field emitted from the antenna pattern directly hits the TFT circuit, the TFT circuit may malfunction.

  Accordingly, an object of the present invention is to provide an RFID inlet that can suppress malfunction of a TFT circuit due to a magnetic field emitted from an antenna pattern.

  To achieve the above object, an RFID inlet according to the present invention includes a substrate, a planar spiral antenna pattern formed on the surface of the substrate, and a TFT circuit formed on the surface of the substrate and connected to the antenna pattern. The TFT circuit includes a highly integrated portion including a circuit element, and a low integrated portion not including the circuit element and including a wiring for interconnecting the circuit elements in the highly integrated portion, The highly integrated portion is provided in a region of the substrate surface that does not overlap with the antenna pattern when viewed from the normal direction of the substrate.

  According to the present invention, since the highly integrated portion is not disposed in the region immediately below (directly above) the antenna pattern that is a magnetic field generation source, it is possible to suppress malfunction of the TFT circuit due to the magnetic field generated from the antenna pattern.

  In the RFID inlet, the low integration portion may be provided in a region of the substrate surface overlapping at least the antenna pattern when viewed from the normal direction of the substrate. According to this, it becomes possible to connect highly integrated parts located on both sides of the antenna pattern.

  In the RFID inlet, the antenna pattern has a spatial region in which a conductor pattern is not arranged in a central portion when viewed from the normal direction of the substrate, and the TFT circuit is a normal line of the substrate among the substrate surfaces. It is good also as providing in the area | region which does not overlap with the said space area | region seeing from a direction. According to this, since the disturbance of the magnetic field does not occur in the central space region of the antenna pattern having the strongest magnetic field distribution, it is possible to suppress the deterioration of the antenna characteristics due to the TFT circuit.

  In the RFID inlet, the TFT circuit may be provided in a region of the substrate surface that overlaps with the antenna pattern formation region when viewed from the normal direction of the substrate. According to this, the disturbance of the magnetic field is further suppressed, and the deterioration of the antenna characteristics due to the TFT circuit can be more effectively suppressed.

  In the RFID inlet, the TFT circuit and the antenna pattern may be formed on the same surface of the substrate.

  According to the present invention, the malfunction of the TFT circuit due to the magnetic field emitted from the antenna pattern can be suppressed.

It is a figure which shows the structure of the RFID inlet by embodiment of this invention. (A) is a top perspective view of the RFID inlet, and (b) is a cross-sectional view taken along line A-A ′ of (a). It is the figure which expanded a part (TFT circuit vicinity) of FIG.1 (b). It is a figure which shows the structure of the RFID inlet by embodiment of this invention, (a) (b) respond | corresponds to (a) (b) of FIG. 1, respectively. It is a schematic diagram of the B-B 'line cross section of Fig.1 (a). It is a figure which shows the structure of the RFID inlet by the modification of embodiment of this invention. (A) is a top perspective view of the RFID inlet, (b) is a cross-sectional view taken along line E-E 'of (a), and (c) is a bottom perspective view of the RFID inlet.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of an RFID inlet 10 according to the present embodiment. 1A is a top perspective view of the RFID inlet 10, and FIG. 1B is a cross-sectional view taken along the line A-A 'of FIG. FIG. 2 is an enlarged view of a part (near the TFT circuit 4) of the cross-sectional view shown in FIG. Note that FIGS. 1B and 2 are drawn greatly extended in the vertical direction of the drawing in order to easily show the configuration appearing in the cross section. Although FIG. 1A is not a cross-sectional view, the TFT circuit and the antenna pattern are hatched for easy understanding. The same applies to each figure described later.

  As shown in FIGS. 1A and 1B, the RFID inlet 10 includes a substrate 2, an antenna pattern 3, a TFT circuit 4, and an insulating layer 5 provided on the surface of the substrate 2, and encapsulates them. And a protective layer 6 to be stopped.

  The substrate 2 is a flat plate material composed of various plastic films. Specifically, as the material of the substrate 2, polyethylene terephthalate (PET), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polycarbonate, A single film such as polyamide, polyimide, cellulose diacetate, cellulose triacetate, polystyrene, ABS resin, polyacrylic ester, polypropylene, polyethylene, polyurethane, acrylic, water-resistant paper, or a composite film thereof can be used. The thickness of the substrate 2 is determined by the standard, and is specifically about 1 μm to 100 μm. In the present embodiment, the substrate 2 having a vertical width of 45 mm and a horizontal width of 75 mm is used, but the size of the substrate 2 is not limited to this.

  The TFT circuit 4 is formed on the upper surface of the substrate 2. The TFT circuit 4 is mainly composed of active elements such as transistors and diodes formed on the surface of the substrate 2, passive elements such as capacitors and resistors, and wirings interconnecting these elements, whereby a rectifier circuit, memory, A communication circuit or the like is configured.

  The insulating layer 6 is formed so as to cover the entire upper surface of the substrate 2 including the TFT circuit 4 by means such as plasma CVD or sputtering. As a specific material of the insulating layer 6, it is preferable to use a layer containing an inorganic material of silicon, silicon oxide or silicon nitride, or a layer containing an organic material such as an organic resin.

  The antenna pattern 3 is a planar spiral conductor pattern as shown in FIG. 1A, and is formed on the upper surface of the insulating layer 6 as shown in FIG. Both ends of the antenna pattern 3 are connected to the TFT circuit 4 via through-hole conductors 3h.

  The antenna pattern 3 and the TFT circuit 4 constitute a so-called passive tag. Hereinafter, the operation of the passive tag constituted by the antenna pattern 3 and the TFT circuit 4 will be briefly described.

  First, a reader (not shown) transmits a radio wave (modulated wave) modulated by data including a read command, and then transmits an unmodulated radio wave (non-modulated wave) over a predetermined time. The rectifier circuit of the TFT circuit 4 receives these radio waves via the antenna pattern 3 and rectifies them into a direct current. The communication circuit operates using this direct current as a power source, first interprets the modulated wave, and reads data from the memory in accordance with the interpretation result. Then, the reflected wave of the non-modulated wave is modulated by the read data. The reader receives the reflected wave, and acquires data stored in the memory in the TFT circuit 4.

  The protective layer 6 is made of a resin material. Specific examples of the material include phenol resin and epoxy resin. When the protective layer 6 is formed, a film-like material is attached from the upper side and the lower side of the substrate 2 and is brought into close contact with the substrate 2, the antenna pattern 3, and the TFT circuit 4 by hot press molding. Thereby, sealing by the protective layer 6 is completed. The thickness of the protective layer 6 is about 1 μm to 100 μm on only one side (one side of the substrate 2), and therefore the thickness of the RFID inlet 10 as a whole is about 3 μm to 300 μm.

  Next, the positional relationship between the antenna pattern 3 and the TFT circuit 4 will be described.

  3A and 3C, three regions on the surface of the substrate 2 classified by the positional relationship with the antenna pattern 3, that is, an inner space region 30, an outer space region 31, and an antenna pattern formation region 32 are illustrated. It is shown.

  The inner space region 30 is a region inside the innermost periphery of the antenna pattern 3 where no conductor pattern is disposed. The outer space area 31 is an area outside the outermost periphery of the antenna pattern 3 where no conductor pattern is arranged. The antenna pattern formation region 32 is a region on the front surface 2a of the substrate 2 where the antenna pattern 3 is formed. The antenna pattern formation region 32 includes a gap region between conductor patterns forming the antenna pattern 3. In other words, the antenna pattern formation region 32 is a region surrounded by the outermost conductor pattern and the innermost conductor pattern among the conductor patterns constituting the antenna pattern formation region 32. In addition, each region does not have to be strictly divided along the edge of the antenna pattern 3, and some error (for example, about 10% of the conductor width of the antenna pattern 3) is allowed.

  The TFT circuit 4 has an inner space region 30 and an outer space region 31 as viewed from the normal direction of the substrate 2 (the depth direction in FIG. 3A and the vertical direction in FIG. 3B) of the surface of the substrate 2. Are preferably provided in a region that does not overlap with the antenna pattern formation region 32. By doing in this way, deterioration of the antenna characteristic by the TFT circuit 4 is suppressed. That is, when the planar spiral antenna pattern 3 is used, the magnetic field distribution is relatively strong in the inner space region 30 (and the space above and below it; the same applies hereinafter). By disposing the TFT circuit 4 so as to avoid an overlapping region when viewed from the normal direction of the substrate 2, the disturbance of the magnetic field by the TFT circuit 4 is suppressed to a considerable extent. Also, the outer space region 31 has a stronger magnetic field distribution than the antenna pattern formation region 32, and the TFT circuit 4 is arranged avoiding an overlapping region when viewed from the normal direction of the outer space region 31 and the substrate 2. The disturbance of the magnetic field by the TFT circuit 4 is suppressed to a considerable extent. On the other hand, since the magnetic field distribution is relatively weak in the antenna pattern forming region 32, the TFT circuit 4 is provided in a region overlapping with the antenna pattern forming region 32 when viewed from the normal direction of the substrate 2. The disturbance of the magnetic field by the TFT circuit 4 is suppressed to a considerable extent.

  However, when the area of the TFT circuit 4 is larger than the area of the antenna pattern formation region 32 or when the area of the TFT pattern 4 is smaller than the area of the antenna pattern formation region 32, the TFT circuit 4 cannot fit into the antenna pattern formation region 32 due to the shape problem. May protrude from the antenna pattern formation region 32. The TFT circuit 4 shown in FIGS. 1 and 3 is an example having such a protrusion. In the examples shown in these drawings, since the TFT circuit 4 has a wide width, the TFT circuit 4 does not fit in the antenna pattern formation region 32 and protrudes into the inner space region 30 and the outer space region 31. Since the magnetic field distribution in the inner space region 30 is stronger than the magnetic field distribution in the outer space region 31, it is preferable that the outer space region 31 protrudes from the inner space region 30 as much as possible.

  As described above, the disturbance of the magnetic field caused by the TFT circuit 4 can be suppressed to a considerable extent by installing the TFT circuit 4 while avoiding regions overlapping with the inner space region 30 and the outer space region 31 as much as possible. By providing the TFT circuit 4 in a region overlapping with the formation region 32, the antenna pattern 3 and the TFT circuit 4 are close to each other, and the TFT circuit 4 may malfunction due to a magnetic field generated from the antenna pattern 3. The RFID inlet 10 according to the present embodiment has a configuration for preventing such malfunction of the TFT circuit 4. This will be specifically described below.

  As shown in FIGS. 1B and 2, the TFT circuit 4 includes a high integration portion 4 a having a relatively high integration degree and a low integration portion 4 b having a relatively low integration degree. The highly integrated portion 4a is configured to include circuit elements such as transistors, diodes, capacitors, resistors, and wirings that interconnect these elements. The low integration portion 4b is composed of only wirings that interconnect circuit elements arranged in the high integration portion 4a. The low integration portion 4b does not include circuit elements.

  The highly integrated portion 4a is provided on the surface of the substrate 2 in a region that does not overlap with the antenna pattern 3 when viewed from the normal direction of the substrate 2 (a region other than the region indicated by symbol C in FIG. 2). The highly integrated portion 4a according to the example of FIG. 1A is divided into a plurality of portions with an area overlapping with the antenna pattern 3 interposed therebetween. This is to secure a certain width of the highly integrated portion 4a. The low integration part 4b is provided mainly for electrically connecting the parts of the high integration part 4a divided in this way, and is an area overlapping with the antenna pattern 3 when viewed from the normal direction of the substrate 2 ( Highly integrated portions 4a provided in a region (indicated by symbol C in FIG. 2) and separated from each other with a region overlapping with the antenna pattern 3 being connected to each other.

  In general, the highly integrated portion 4a having a relatively high degree of integration is more susceptible to the influence of a magnetic field than the low integration portion 4b having a relatively low integration degree. By providing in a region that does not overlap with the antenna pattern 3 when viewed from the line direction, the magnetic field applied to the highly integrated portion 4a becomes relatively weak.

  FIG. 4 is a schematic diagram of a cross section taken along line B-B ′ of FIG. In the figure, only the antenna pattern 3 is shown. As shown in the figure, since currents in the same direction flow in adjacent conductor patterns such as the two conductor patterns on the left side in the drawing, the directions of the magnetic fields generated by these patterns are the same. Therefore, the generated magnetic fields cancel each other in the region between these conductor patterns, and the region corresponding to the antenna pattern formation region 32 has a particularly weak magnetic field distribution. Providing the highly integrated portion 4a in a region that does not overlap with the antenna pattern 3 when viewed from the normal direction of the substrate 2 means providing the highly integrated portion 4a at a position where the magnetic field distribution is particularly weak. Therefore, the magnetic field applied to the highly integrated portion 4a becomes relatively weak.

  As described above, since the magnetic field applied to the highly integrated portion 4a is relatively weak, malfunctioning of the TFT circuit 4 due to the magnetic field emitted from the antenna pattern 3 is suppressed in the RFID inlet 10.

  In addition, according to the structure of the RFID inlet 10 described above, there is also an effect that the pressure from the normal direction of the substrate 2 becomes stronger. That is, as shown in FIG. 2, when pressure from the normal direction (pressure from the direction indicated by arrow D in FIG. 2) is applied to the substrate 2, the pressure is further away from the substrate 2. Concentrate on a certain antenna pattern 3. Accordingly, a considerable pressure is also applied to the low integration portion 4b directly below, but the pressure applied to the high integration portion 4a provided in a region not overlapping with the antenna pattern 3 when viewed from the normal direction of the substrate 2 is Relatively relaxed. As a result, damage to the TFT circuit 4 is alleviated. In addition, as a specific example in the case where such pressure is applied, an example of the RFID inlet 10 used by being incorporated in paper can be given. In the paper making process for manufacturing paper, a process (calendar process) is performed to crush the paper in which the RFID inlet 10 has been engraved with a roller (calendar process). The structure is relatively strong against the pressure applied in the process.

  Further, since the antenna pattern 3 and the TFT circuit 4 are formed on the same surface of the substrate 2, a through-hole conductor for connecting them to each other is not necessary. Therefore, the manufacturing process of the RFID inlet 10 is simplified, and cost reduction is realized.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to such embodiment at all, and this invention can be implemented in various aspects in the range which does not deviate from the summary. Of course.

  For example, although the antenna pattern 3 and the TFT circuit 4 are formed on the same surface of the substrate 2 in the above embodiment, they may be formed on different surfaces.

  FIG. 5 is a view showing the RFID inlet 10 in which the antenna pattern 3 is formed on one surface of the substrate 2 and the TFT circuit 4 is formed on the other surface. 5A is a top perspective view of the RFID inlet 10 according to this modification, FIG. 5B is a cross-sectional view taken along the line EE ′ of FIG. 5A, and FIG. 5C is the RFID inlet. 10 is a bottom perspective view of FIG. Also in this modification, the highly integrated portion 4 a is provided in a region of the surface of the substrate 2 that does not overlap with the antenna pattern 3 when viewed from the normal direction of the substrate 2. On the other hand, the low integration portion 4 b is provided in a region overlapping with the antenna pattern 3 when viewed from the normal direction of the substrate 2. By doing so, malfunction of the TFT circuit 4 due to the magnetic field emitted from the antenna pattern 3 is suppressed.

2 Substrate 2a Front surface 2b Back surface 3 Antenna pattern 3h Through-hole conductor 4 TFT circuit 4a High integration portion 4b Low integration portion 5 Insulating layer 6 Protective layer 10 RFID inlet 30 Inner space region 31 Outer space region 32 Antenna pattern formation region

Claims (5)

A substrate,
A planar spiral antenna pattern formed on the surface of the substrate;
A TFT circuit formed on the surface of the substrate and connected to the antenna pattern;
The TFT circuit has a highly integrated portion including circuit elements, and a low integrated portion that does not include circuit elements and includes wiring for interconnecting the circuit elements in the highly integrated portion,
The high-integration portion is provided in a region of the substrate surface that does not overlap with the antenna pattern when viewed from the normal direction of the substrate.   2. The RFID inlet according to claim 1, wherein the low integration portion is provided in a region of the substrate surface overlapping with the antenna pattern when viewed from at least a normal direction of the substrate. The antenna pattern has a spatial region in which a conductor pattern is not arranged in a central portion when viewed from the normal direction of the substrate,
3. The RFID inlet according to claim 1, wherein the TFT circuit is provided in a region of the substrate surface that does not overlap with the space region when viewed from the normal direction of the substrate.   4. The RFID inlet according to claim 3, wherein the TFT circuit is provided in a region of the substrate surface that overlaps with a region where the antenna pattern is formed when viewed from the normal direction of the substrate.   The RFID inlet according to any one of claims 1 to 4, wherein the TFT circuit and the antenna pattern are formed on the same surface of the substrate.

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