JP2009239487A - Planar antenna element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar antenna element capable of omitting or reducing an element for adjusting a frequency. <P>SOLUTION: The planar antenna element includes: a spiral and planar antenna pattern 110; and parallel resonance patterns 121-124 arranged in the upper layer of the antenna pattern 110 and performing capacitive coupling between a part positioned on a relatively inner peripheral side and a part positioned on a relatively outer peripheral side in the antenna pattern 110. Consequently, the parallel resonance patterns 121-124 give a frequency adjustment function to the antenna element itself, thereby omitting or reducing the element for adjusting the frequency. Besides, since the parallel resonance patterns perform the capacitive coupling between the part positioned on the inner peripheral side and the part positioned on the outer peripheral side in the antenna pattern, the outer shape of the antenna element is not enlarged. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar antenna element and a manufacturing method thereof, and more particularly to an antenna element having a spiral planar antenna pattern and a manufacturing method thereof.

  In recent years, electronic money using non-contact IC tags has become widespread (see Patent Document 1). Since such a non-contact IC tag is used by being built in a thin card or affixed to a casing of a cellular phone, a spiral planar antenna is used as an antenna element used for the non-contact IC tag. A planar antenna element having a pattern is used.

  As a method for manufacturing a planar antenna element, a method of printing a conductive ink on an insulating film, a method of etching a metal foil laminated on the insulating film, a method of thermally transferring a metal foil on the insulating film, etc. are mainly used. It is used. Among them, the method of thermally transferring a metal foil has a feature that it can be manufactured at a low cost because the design time is extremely short because a printer or the like can be used (see Patent Document 2).

Currently, the frequency used for contactless IC tags is about 13.56 MHz, which is a relatively low frequency region. For this reason, if an attempt is made to realize resonance in this frequency band using only a spiral antenna pattern, the antenna pattern becomes very large and cannot be built in a card or a mobile phone. For this reason, in order to realize the above resonance frequency with a smaller antenna pattern, it is necessary to connect a chip capacitor for frequency adjustment.
Japanese Patent No. 3150575 JP 2007-324641 A

  Thus, the conventional planar antenna element has a problem that the number of parts increases because frequency adjustment is performed using a chip capacitor or the like. Further, since the frequency adjusting chip capacitor is mounted on the circuit board side on which the transmission / reception circuit is formed, it is necessary to design the circuit board in consideration of the characteristics of the planar antenna element, which makes the design complicated. There was also a problem.

  Another possible method is to use a multilayer circuit board as the circuit board on which the transmission / reception circuit is formed and adjust the frequency using a capacitor pattern formed inside the board. However, with this method, once the circuit board is designed, the capacitance cannot be changed, and the degree of freedom in design is greatly reduced. Further, as in the case of using a chip capacitor, it is necessary to design a circuit board in consideration of the characteristics of the planar antenna element.

  Furthermore, a method of providing a branch pattern in a part of the antenna pattern and connecting it to a plurality of capacitance patterns in advance is also conceivable. In this case, at the time of adjustment, the resonance frequency can be changed by cutting a part of the branch pattern. However, this method has a problem of low mass productivity because it requires a complicated and inefficient work of cutting the branch pattern. Further, since the capacitance pattern is formed in advance, the adjustable range is limited depending on the number and shape thereof, and there is a problem that fine adjustment cannot be performed. Furthermore, there is a possibility that a capacitance pattern that is no longer used due to the cutting of the branch pattern may interfere with radiation. In addition, since the branch pattern is directly connected to the antenna pattern, the antenna characteristics themselves are strongly influenced by the branch pattern, and as a result, it is difficult to obtain good characteristics.

  Accordingly, an object of the present invention is to provide an improved planar antenna element having a spiral planar antenna pattern and a method for manufacturing the same.

  Another object of the present invention is to provide a planar antenna element capable of omitting or reducing the frequency adjusting element and a method for manufacturing the same.

  The planar antenna element according to the present invention is separated from the antenna pattern in a direct current manner by being provided in a spiral planar antenna pattern and a layer different from the antenna pattern, and is relatively on the inner peripheral side of the antenna pattern. A parallel resonance pattern that capacitively couples the position portion to the position portion relative to the outer peripheral side is provided.

  According to the present invention, since a frequency adjustment function is given to the antenna element itself by the parallel resonance pattern, a desired resonance frequency can be realized by a smaller antenna pattern. In addition, since the parallel resonance pattern capacitively couples the position portion on the inner peripheral side and the position portion on the outer peripheral side of the antenna pattern, the outer shape of the antenna element is not increased. In addition, since the parallel resonance pattern and the antenna pattern are separated from each other in a direct current manner, it is not necessary to use a portion connected to the antenna pattern such as a branch pattern, which adversely affects antenna characteristics. There is nothing.

  In the present invention, the antenna pattern includes a first portion, a second portion adjacent to the first portion and positioned on the inner peripheral side as viewed from the first portion, and a second portion adjacent to the second portion. At least a third portion located on the inner periphery side, and the parallel resonance pattern may be capacitively coupled to the other two without being capacitively coupled to any one of the first to third portions. I do not care. According to this, the resonant frequency can be finely adjusted by capacitively coupling the first and second parts located on the outer peripheral side, for example, and the second and third parts located on the inner peripheral side As a result of the capacitive coupling, it is possible to obtain a significant reduction effect of the resonance frequency.

  The parallel resonance pattern is preferably provided on the side opposite to the radiation direction of the antenna pattern. According to this, it becomes possible to reduce the loss in the radiation direction due to the parallel resonance pattern.

  The antenna pattern preferably has a plurality of linear portions and a plurality of corner portions located at both ends of the linear portion, and the parallel resonance pattern is preferably arranged at substantially the center of the linear portion. Since the corner portion of the antenna pattern is the portion where the magnetic field is strongest, the loss can be reduced by arranging the parallel resonance pattern in a portion far from the corner portion.

  In the present invention, it is preferable that a capacitive electrode pattern is provided on at least one of the parallel resonance pattern and the antenna pattern at a portion where the parallel resonance pattern and the antenna pattern intersect. This makes it possible to obtain a larger capacitance.

  The planar antenna element according to the present invention preferably includes a plurality of parallel resonance patterns, and the plurality of parallel resonance patterns are distributed substantially uniformly in the circumferential direction of the antenna pattern. According to this, the bias of the electromagnetic wave radiated from the antenna pattern can be reduced, and the interference of the electromagnetic wave radiated by the parallel resonance pattern is suppressed.

  The planar antenna element according to the present invention preferably further includes a lead-out wiring pattern having one end electromagnetically coupled to the inner or outer peripheral end of the antenna pattern and the other end drawn to the outside or the inside of the antenna pattern. According to this, even when the antenna pattern is formed using a laminate of a conductor film and an insulating film as in the thermal transfer method, the electrode can be easily pulled out from the inner peripheral edge of the antenna pattern, or the antenna pattern It is possible to easily pull the electrode from the outer peripheral end. In addition, since the antenna pattern and the lead-out wiring pattern are separated from each other in a direct current manner, the impedance matching function between the antenna element and the transmission / reception circuit can be provided in the electromagnetic field coupling portion, and an impedance matching element is not required. .

  In this case, the inner peripheral end of the antenna pattern and one end of the lead-out wiring pattern constitute a capacitive electrode pattern, and both of them may be capacitively coupled. Constitutes a coil pattern, and both of them may be inductively coupled. These can be appropriately selected according to required characteristics.

  In the present invention, the lead wiring pattern and the parallel resonance pattern are preferably formed in the same layer. According to this, since the lead-out wiring pattern and the parallel resonance pattern can be formed at the same time, the manufacturing cost can be reduced.

  In the present invention, it is preferable that a capacitor electrode pattern is provided on at least one of the lead-out wiring pattern and the antenna pattern at a portion where the lead-out wiring pattern and the antenna pattern intersect. According to this, since the intersection of the lead-out wiring pattern and the antenna pattern exhibits the same function as the parallel resonance pattern, it is possible to obtain a larger capacitance.

  It is preferable that the parallel resonance pattern and the lead-out wiring pattern are distributed substantially uniformly in the circumferential direction of the antenna pattern. According to this, the bias of the electromagnetic wave radiated from the antenna pattern can be reduced, and the interference of the electromagnetic wave radiated by the parallel resonance pattern is suppressed.

  The planar antenna element according to the present invention further includes a support, and the antenna pattern and the parallel resonance pattern are preferably attached to the support via an adhesive layer. Such a structure can be obtained by a method that can be manufactured at a low cost with a very short design time, such as a thermal transfer method.

  A method of manufacturing a planar antenna element according to the present invention includes a step of forming a spiral planar antenna pattern having a resonance frequency higher than a target resonance frequency, a step of measuring the resonance frequency of the antenna pattern, and a measurement Obtaining a capacitance value necessary for adjustment based on the resonance frequency and the target resonance frequency, and relative to a portion located relatively on the inner circumference side of the antenna pattern based on the capacitance value And a step of forming a parallel resonance pattern for capacitively coupling a portion located on the outer peripheral side.

  According to the present invention, since the resonance frequency can be adjusted later by the parallel resonance pattern, an antenna pattern having a resonance frequency higher than the target resonance frequency can be used. Further, since it is only necessary to form parallel resonance patterns as much as necessary for adjustment, unnecessary capacitance patterns do not remain.

  As described above, according to the present invention, the frequency adjustment function is given to the antenna element itself by the parallel resonance pattern, so that a desired resonance frequency can be realized by a smaller antenna pattern. Thereby, it is not necessary to use an element for frequency adjustment on the circuit board side on which the transmission / reception circuit is formed, or at least such elements can be reduced.

  In particular, when the frequency adjustment element is not required, the circuit board on which the transmission / reception circuit is formed and the antenna element can be designed independently, so that the degree of design freedom can be greatly increased.

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

  FIG. 1 is a schematic plan view showing the structure of a planar antenna element 100 according to a preferred first embodiment of the present invention. 2 is a schematic cross-sectional view taken along the line AA shown in FIG.

  As shown in FIGS. 1 and 2, the planar antenna element 100 according to the present embodiment includes an insulating film 101 as a support, a spiral planar antenna pattern 110 attached to the insulating film 101, and an antenna. Parallel resonance patterns 121 to 124 and a lead-out wiring pattern 130 attached to the upper layer of the pattern 110 are provided. In the planar antenna element 100 according to the present embodiment, the outer peripheral end 110b of the antenna pattern 110 is used as one feeding terminal P1, and the outer end 130b of the lead-out wiring pattern 130 is used as the other feeding terminal P2.

  Although not particularly limited, the planar antenna element 100 according to the present embodiment can be used as an antenna element for a non-contact IC tag. In this case, as shown in FIG. 3, the two power supply terminals P1 and P2 are connected to the transmission / reception circuit 50, thereby configuring an antenna device. The transmission / reception circuit 50 is formed on a circuit board (not shown) separate from the planar antenna element 100.

  An adhesive layer 190 is provided on the bottom surface (surface on the insulating film 101 side) of the antenna pattern 110, the parallel resonance patterns 121 to 124, and the lead-out wiring pattern 130, and the adhesive layer 190 is attached to the insulating film 101. . The antenna pattern 110, the parallel resonance patterns 121 to 124, and the lead-out wiring pattern 130 having such a configuration can be formed by a thermal transfer method using a printer or the like.

As shown in FIG. 1, the antenna pattern 110 has a spiral shape, and the inner peripheral end 110a forms a capacitive electrode pattern with an enlarged area. As described above, the outer peripheral end 110b is used as one power supply terminal P1. The shape of the antenna pattern 110 will be described in more detail. The outer shape of the antenna pattern 110 is substantially rectangular, and includes a plurality of linear portions 110s _{1 to} 110s ₁₂ and a plurality of corner portions 110c located at both ends thereof. Here, the straight portions 110s ₁ , 110s ₅ , 110s ₉ are located on the short side S1 side, and the straight portions 110s ₂ , 110s ₆ , 110s ₁₀ are located on the long side L1 side, and the straight portions 110s ₃ , 110s ₇ , 110s are located. ₁₁ is located on the short side side S2, the linear portion 110s _4, 110s _8, 110s ₁₂ is located on the long side L2 side. In the example shown in FIG. 1, the number of turns of the antenna pattern 110 is three turns, but the number of turns is not limited to this.

Further, since the antenna pattern 110 has a spiral shape, a portion positioned relatively on the inner periphery side and a portion positioned relatively on the outer periphery side are adjacent in the radial direction. For example, among the straight line portions located on the short side S1 side, the straight line portion 110s ₅ relatively located on the inner peripheral side and the straight line portion 110s ₁ relatively located on the outer peripheral side are adjacent to each other. Similarly, the linear portion 110s ₉ relatively located on the inner peripheral side and the linear portion 110s ₅ relatively located on the outer peripheral side are adjacent to each other. The same applies to the straight line portions corresponding to the other sides S2, L1, and L2.

In the present embodiment, the substantially central portion of the adjacent linear portions is covered with the parallel resonance patterns 121 to 124 in this way. Of these, the parallel resonant pattern 121 is disposed so as to cover the linear portion 110s _1, 110s _5, 110s ₉ located on the short side side S1, parallel resonant pattern 122 is straight portion 110s ₂ located on the long side L1 side , 110s ₆ , 110s ₁₀ are arranged so as to cover the parallel resonance pattern 123, and the parallel resonance patterns 123 are arranged so as to cover the straight portions 110s ₃ , 110s ₇ , 110s ₁₁ located on the short side S2 side. Is arranged so as to cover the straight portions 110s ₄ , 110s ₈ , 110s ₁₂ located on the long side L2 side. The parallel resonance patterns 121 to 124 are not in contact with the antenna pattern 110 and are therefore separated from the antenna pattern 110 in a direct current manner.

  Although not particularly limited, in the present embodiment, the widths W4 (lengths in the circumferential direction) of the parallel resonance patterns 121 to 124 are set to be equal to each other. The width W4 may be determined based on the required capacitance.

  As shown in FIG. 2, the parallel resonance patterns 121 to 124 and the antenna pattern 110 are insulated by an adhesive layer 190 provided on the bottom surface of the parallel resonance patterns 121 to 124. Therefore, portions of the antenna pattern 110 that are covered by the parallel resonance patterns 121 to 124 are capacitively coupled via the parallel resonance patterns 121 to 124. In order to further reduce the width W4 of the parallel resonance patterns 121 to 124, a material having a higher dielectric constant may be selected as the material of the adhesive layer 190.

  FIG. 4 is an equivalent circuit diagram of the planar antenna element 100 according to the present embodiment.

As shown in FIG. 4, the parallel resonance patterns 121 to 124 give a capacitance between three linear portions located on the same side. For example, the parallel resonant pattern 121 disposed on the short side S1 gives a capacitance C11 between the straight portion 110s _1, giving a capacitance C12 between the straight portion 110s _5, the capacitance between the straight portion 110s ₉ C13 is given. As a result, the straight portions 110 s ₁ , 110 s ₅ , and 110 s ₉ are capacitively coupled to each other via the parallel resonance pattern 121. The same applies to the parallel resonance patterns 122 to 124 arranged on the other sides S2, L1, and L2.

  As a result, the antenna pattern 110 itself has a large capacitance, and as a result, a lower resonance frequency can be obtained. In addition, in the present embodiment, since the parallel resonance patterns 121 to 124 are arranged on the sides S1, L1, S2, and L2, the parallel resonance patterns 121 to 124 are distributed substantially evenly in the circumferential direction of the antenna pattern 110. Will be. As a result, the bias of the electromagnetic waves radiated from the antenna pattern 110 is reduced, and the interference of the electromagnetic waves radiated by the parallel resonance patterns 121 to 124 is suppressed.

  Moreover, in this embodiment, since the parallel resonance patterns 121-124 are arrange | positioned in the approximate center of a linear part, it becomes possible to reduce the loss resulting from the parallel resonance patterns 121-124. That is, since the corner portion 110c of the antenna pattern 110 is the portion where the magnetic field is the strongest, if a parallel resonance pattern is disposed in the vicinity thereof, the emission of electromagnetic waves is hindered. On the other hand, if the parallel resonance patterns 121 to 124 are arranged at substantially the center of the straight line portion as in this embodiment, such a problem can be minimized.

  Furthermore, in the present embodiment, since the outer shape of the antenna pattern 110 is substantially rectangular, when a large number of planar antenna elements 100 are taken, the antenna pattern 110 is formed on one insulating film 101 with almost no gap. Can do. For this reason, since many antenna patterns 110 can be formed in one insulating film 101, it becomes possible to reduce manufacturing cost.

  Returning to FIG. 1, the end portion 130a on the inner peripheral side of the lead-out wiring pattern 130 constitutes a capacitive electrode pattern having an enlarged area. The end portion 130a of the lead-out wiring pattern 130 covers the upper portion of the inner peripheral end 110a of the antenna pattern 110, whereby both are capacitively coupled. Such a capacitance corresponds to the capacitance C20 shown in FIG. This makes it possible to correctly connect metal foils transferred by a thermal transfer method or the like.

  That is, since the adhesive layer is laminated | stacked on the metal foil transcribe | transferred by the thermal transfer method etc., there exists a problem that it is difficult to connect two metal foils. For this reason, when the spiral planar antenna pattern 110 is formed by the thermal transfer method, it becomes a problem how to connect the inner peripheral end 110a of the antenna pattern 110 to the transmission / reception circuit 50.

  As a method for solving such a problem, there is a method in which a terminal connected to the inner peripheral end 110a of the antenna pattern 110 is formed on the circuit board side on which the transmission / reception circuit 50 is formed. However, in this method, since it is necessary to strictly define the relative positional relationship between the circuit board and the antenna element 100, not only is the design complicated, but there is a problem that versatility cannot be imparted. Arise.

  Or the method of solder-connecting the side surface of two metal foils which should be connected is also known. However, this method requires a step of supplying solder, which increases manufacturing costs and decreases productivity. Further, since the connection between the two metal foils is a side connection by solder, the connection is unstable and the reliability is also lowered.

  Furthermore, as described in Patent Document 2, a method of connecting metal foils by partially removing an insulating film attached to the transferred metal foil has also been proposed. However, in this method, it is necessary to add a step of removing the insulating film, so that the manufacturing cost also increases and the productivity decreases.

  On the other hand, two metal foils to be connected as in the present embodiment, that is, the end portion 130a of the lead-out wiring pattern 130 and the inner peripheral end 110a of the antenna pattern 110 are not connected in a DC manner, but a capacitance. Since both are connected by capacitive coupling (capacitance C20) using an electrode pattern, the above problem can be solved. In addition, since the antenna pattern 110 and the lead-out wiring pattern 130 are separated in a direct current manner, the capacitance C20 can also be used as an impedance matching element. In this case, it is not necessary to use an impedance matching element on the circuit board side, and the number of components can be reduced.

  Moreover, in the present embodiment, since the lead-out wiring pattern 130 and the parallel resonance patterns 121 to 124 are all formed in the upper layer of the antenna pattern 110, they can be formed at the same time, thereby reducing the manufacturing cost. Is possible. Further, since the parallel resonance patterns 121 to 124 are formed in the upper layer of the antenna pattern 110, it is possible to easily finely adjust or change the resonance frequency by additionally forming another parallel resonance pattern. .

  In the present embodiment, the antenna pattern 110 is formed in the lower layer, and the parallel resonance patterns 121 to 124 and the lead-out wiring pattern 130 are formed in the upper layer, but this may be reversed. Which is the upper layer and which is the lower layer may be determined based on the radiation direction of the electromagnetic wave. That is, when the parallel resonance patterns 121 to 124 and the lead-out wiring pattern 130 are formed in the upper layer as in the present embodiment, radiation in the B direction shown in FIG. 2 is not hindered, whereas radiation in the C direction is parallel resonance pattern. 121 to 124 and the lead-out wiring pattern 130 are somewhat hindered. Therefore, this embodiment is suitable when the intended radiation direction is the B direction.

  In contrast, when the parallel resonance patterns 121 to 124 and the lead-out wiring pattern 130 are formed in the lower layer and the antenna pattern 110 is formed in the upper layer, the radiation in the B direction is parallel to the parallel resonance patterns 121 to 124. 124 and the lead-out wiring pattern 130 are somewhat hindered. Therefore, this layout is suitable when the intended radiation direction is the C direction.

  In this embodiment, four parallel resonance patterns 121 to 124 are used. However, the number, position, and shape of the parallel resonance patterns to be used can be appropriately adjusted according to required characteristics. is there.

  Here, the influence of the number and position of the parallel resonance patterns will be described.

  FIG. 5 shows an example in which the number of parallel resonance patterns is changed, and (a) to (c) show examples in which the number of parallel resonance patterns is 1 to 3, respectively.

  In the example shown in FIG. 5A, only the parallel resonance pattern 122 is used, and its width W1 is set to four times the width W4 shown in FIG. In the example shown in FIG. 5B, the parallel resonance patterns 121 and 123 are used, and the width W2 thereof is set to twice the width W4 shown in FIG. In the example shown in FIG. 5C, the parallel resonance patterns 121 to 123 are used, and the width W3 thereof is set to 4/3 times the width W4 shown in FIG. Thereby, the capacitance obtained by the parallel resonance pattern is the same as that of the embodiment shown in FIG. 1 in the examples shown in FIGS.

  However, the characteristics obtained are improved in the order of the example shown in FIG. 5A, the example shown in FIG. 5B, and the example shown in FIG. 5C, and the embodiment shown in FIG. Become. This is because if one parallel resonance pattern is thick, radiation of electromagnetic waves tends to be hindered, and if there is an uneven portion in the arrangement of the parallel resonance patterns, the bias of electromagnetic waves increases. However, this does not mean that the examples shown in FIGS. 5A to 5C are outside the scope of the present invention.

  As shown in FIG. 5A, when only one parallel resonance pattern is used, it is preferably arranged on the long side L1 or L2 (long side L1 in the example shown in FIG. 5A). This is because the corner portion 110c of the antenna pattern 110 is a portion where the magnetic field is the strongest, and therefore it is desirable to arrange the parallel resonance pattern 122 in a portion far from the corner portion 110c in order to reduce the loss. . On the other hand, as shown in FIG. 6, when the parallel resonance pattern 122 is arranged at the corner 110c of the antenna pattern 110, the radiation from the antenna pattern 110 is hindered in this portion, and the uniformity of the radiation pattern and the radiation efficiency are lowered. To do. Further, in the example shown in FIG. 5A, the parallel resonance pattern 122 and the lead wiring pattern 130 are distributed substantially uniformly in the circumferential direction of the antenna pattern 110. For this reason, the bias of the electromagnetic waves radiated from the antenna pattern 110 is reduced.

  On the other hand, as shown in FIG. 5B, when two parallel resonance patterns are used, it is preferable to dispose them on the short sides S1 and S2. This is because the electromagnetic wave bias increases when the linear distance between the parallel resonance patterns is short. However, when the parallel resonance pattern is arranged on the short sides S1 and S2, the distance between the parallel resonance pattern and the corner portion 110c becomes close, and the loss increases. Therefore, when two parallel resonance patterns are used, whether to arrange them on the short side or on the long side may be determined in consideration of the balance between the uniformity of the radiation pattern and the radiation efficiency. In any case, it is preferable that these two parallel resonance patterns are distributed substantially uniformly in the circumferential direction of the antenna pattern 110.

  Further, as shown in FIG. 5 (c), when three parallel resonance patterns are used, it is preferable to arrange them on two short sides S1, S2 and one long side L1, respectively. Thereby, a parallel resonance pattern can be kept away from the corner | angular part 110c, ensuring the linear distance of parallel resonance patterns. However, in consideration of the balance between the uniformity of the radiation pattern and the radiation efficiency, these three parallel resonance patterns may be arranged on the two long sides L1, L2 and one short side S1, respectively. In any case, it is preferable that these three parallel resonance patterns are distributed substantially uniformly in the circumferential direction of the antenna pattern 110.

  In the present embodiment, the parallel resonance patterns 121 to 124 are provided so as to cover the three adjacent linear portions, but if arranged so as to cover at least two of the antenna patterns 110, the antenna pattern Capacitance can be provided to 110.

FIG. 7 shows an example in which a parallel resonance pattern is arranged so as to cover two adjacent straight portions, and (a) shows a parallel resonance so as to cover the straight portions 110s ₆ and 110s ₁₀ without covering the straight portions 110s _2. It shows an example in which the pattern 125 shows an example in which a parallel resonance pattern 125 to cover the linear portion 110s _2, 110s ₆ without covering the (b) linear portions 110s _10. That is, in the example shown in FIG. 7A, the parallel resonance pattern 125 is arranged on the inner peripheral side, whereas in the example shown in FIG. 7B, the parallel resonance pattern 125 is arranged on the outer peripheral side. Thus, in the example shown in FIG. 7 (a), the parallel resonance pattern 125 without linear portion 110s ₂ capacitively coupled, capacitively coupling the linear portion 110s ₆ and the straight portion 110s _10. Similarly, in the example shown in FIG. 7 (b), a parallel resonant pattern 125 without binding linear portion 110s ₁₀ and the capacitor, capacitively coupling the linear portion 110s ₂ and the straight portion 110s _6.

  The capacitance obtained by the parallel resonance pattern 125 is the same between FIGS. 7 (a) and 7 (b). However, the resulting resonance frequency reduction effect is greater in the example shown in FIG. 7A and smaller in the example shown in FIG. 7B. Therefore, in order to further reduce the resonance frequency, the parallel resonance pattern 125 may be arranged on the inner peripheral side as shown in FIG. On the other hand, in order to finely adjust the resonance frequency, a parallel resonance pattern 125 may be arranged on the outer peripheral side as shown in FIG.

  Next, a method for manufacturing the planar antenna element 100 will be described.

  First, an antenna pattern designed so that the resonance frequency is higher than the target resonance frequency in advance is formed. Next, the characteristics of the antenna pattern are measured using an impedance analyzer, and the frequency of the peak value of the real part of the impedance is obtained. Based on the obtained frequency, a capacitance value necessary for the parallel resonance pattern is calculated. At this time, if a table showing the relationship between the capacitance value and the amount of change in frequency is created in advance, the required capacitance value can be quickly determined. When the capacitance value necessary for adjustment is determined, a parallel resonance pattern that provides this capacitance value is formed on the antenna pattern. And the characteristic of an antenna pattern is measured again using an impedance analyzer, and the adjusted frequency is confirmed. If the adjustment is not sufficient, the capacitance value to be added is calculated, and the parallel resonance pattern is added.

  Thus, the design of the planar antenna element 100 is completed. When the design is completed, mass production is possible if the antenna pattern and the parallel resonance pattern are formed as designed.

  Next, a second preferred embodiment of the present invention will be described.

  FIG. 8 is a schematic plan view showing the structure of a planar antenna element 200 according to the second preferred embodiment of the present invention.

  As shown in FIG. 8, in the planar antenna element 200 according to the present embodiment, the inner peripheral end 210a of the antenna pattern 210 and the inner peripheral end 230a of the lead-out wiring pattern 230 are spiral and constitute a coil pattern. is doing. FIG. 8 shows a state where the lead-out wiring pattern 230 is separated in consideration of the visibility of the drawing, but actually, the lead-out wiring pattern 230 is arranged in a region D indicated by a broken line. The outer peripheral edge 210b of the antenna pattern 210 and the outer peripheral edge 230b of the lead-out wiring pattern 230 are used as power supply terminals P1 and P2, respectively. Since the other points are the same as those of the planar antenna element 100 shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  The coil pattern constituted by the end portion 230a of the lead-out wiring pattern 230 covers the coil pattern constituted by the inner peripheral end 210a of the antenna pattern 210, whereby both are inductively coupled. Therefore, it is possible to correctly couple the two without connecting them in a DC manner. The inductance obtained by such inductive coupling can be used for impedance matching between the antenna element and the transmission / reception circuit. Therefore, it is only necessary to select whether to use a capacitive electrode pattern as shown in FIG. 1 or a coil pattern as shown in FIG. 8 according to a constant required for impedance matching.

  Next, a preferred third embodiment of the present invention will be described.

  FIG. 9 is a schematic plan view showing the structure of a planar antenna element 300 according to a preferred third embodiment of the present invention.

  As shown in FIG. 9, in the planar antenna element 300 according to the present embodiment, the width of the antenna pattern 310 is expanded in the radial direction at the portion where the antenna pattern 310 and the lead-out wiring pattern 330 intersect, and this portion is A capacitive electrode pattern is formed. Since the other points are the same as those of the planar antenna element 100 shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, since the intersection between the antenna pattern 310 and the lead-out wiring pattern 330 exhibits the same function as the parallel resonance patterns 121 to 124, it is possible to obtain a larger capacitance.

  Next, a preferred fourth embodiment of the present invention will be described.

  FIG. 10 is a schematic plan view showing the structure of a planar antenna element 400 according to a preferred fourth embodiment of the present invention.

  As shown in FIG. 10, in the planar antenna element 400 according to the present embodiment, the width of the lead-out wiring pattern 430 is expanded in the circumferential direction at the portion where the antenna pattern 410 and the lead-out wiring pattern 430 intersect. Constitutes a capacitive electrode pattern. Since the other points are the same as those of the planar antenna element 100 shown in FIG. 1, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  Also in the present embodiment, as in the above-described third embodiment, the intersection between the antenna pattern 410 and the lead-out wiring pattern 430 exhibits the same function as the parallel resonance patterns 121 to 124, so that a larger capacitance is obtained. It becomes possible.

  In the third and fourth embodiments, the width of one of the antenna pattern and the lead-out wiring pattern is enlarged at the intersection of the antenna pattern and the lead-out wiring pattern. Both widths of the pattern may be enlarged. Furthermore, the capacitance may be adjusted by reducing the width of one or both of the antenna pattern and the lead wiring pattern at the intersection.

  In the third embodiment, the width of the antenna pattern is enlarged at the intersection with the lead-out wiring pattern. However, as shown in FIG. 11, the width of the antenna pattern is enlarged at the intersection with the parallel resonance pattern. It is also possible to do. Similarly, in the fourth embodiment, the width of the lead wiring pattern is enlarged at the intersection with the antenna pattern. However, as shown in FIG. 12, the width of the parallel resonance pattern is increased at the intersection with the antenna pattern. It is also possible to enlarge. According to these, a larger capacitance can be obtained.

  Next, a preferred fifth embodiment of the present invention will be described.

  FIG. 13 is a schematic plan view showing the structure of a planar antenna element 500 according to a preferred fifth embodiment of the present invention.

  As shown in FIG. 13, in the planar antenna element 500 according to the present embodiment, the outer shape of the spiral antenna pattern 510 is circular, and almost the whole is constituted by a curved portion. Also in the present embodiment, the outer peripheral end 510b of the antenna pattern 510 constitutes the power feeding terminal P1, and the inner peripheral end 510a is capacitively coupled to the inner peripheral end 530a of the lead-out wiring pattern 530. An end portion 530b on the outer peripheral side of the lead wiring pattern 530 constitutes a power feeding terminal P2.

  In the present embodiment, three parallel resonance patterns 521 to 523 are provided in the upper layer of the antenna pattern 510. As shown in FIG. 5C, when the outer shape of the antenna pattern is a quadrangle, it is difficult to completely evenly arrange the three parallel resonance patterns in the circumferential direction while avoiding the corner portion 110c. On the other hand, if the outer shape of the antenna pattern 510 is circular as in the present embodiment, there is no corner, and therefore any number of parallel resonance patterns can be arranged almost completely in the circumferential direction. . That is, when n parallel resonance patterns are used, it is possible to realize a substantially complete uniform arrangement by arranging the parallel resonance pattern and the lead-out wiring pattern at a position where the antenna pattern 510 is equally divided into n + 1 in the circumferential direction. Become.

  Although several preferred 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 without departing from the spirit of the present invention. It goes without saying that these are included in the scope of the present invention.

  For example, the number of parallel resonance patterns that can be arranged in one linear portion of the antenna pattern is not limited to one, and a plurality of parallel resonance patterns may be arranged according to the target characteristics. FIG. 14 is a diagram illustrating an example in which various variations of parallel resonance patterns are arranged. The shapes of the antenna pattern 110 and the lead-out wiring pattern 130 are the same as those in FIG. The example shown in FIG. 14 is obtained, for example, when the parallel resonance patterns 625 to 629 are additionally formed for the purpose of fine adjustment or change of the resonance frequency after the main parallel resonance patterns 621 to 624 are formed. It is an example of a layout. As described above, if the parallel resonance pattern is formed a plurality of times, the resonance frequency can be finely adjusted or changed.

  Further, the lead-out wiring pattern is not limited to the one in which the inner peripheral end of the antenna pattern is drawn out to the outside of the antenna pattern. As shown in FIG. 15, the outer peripheral end 710b of the antenna pattern 710 is surrounded by the inner periphery of the antenna pattern. The area 700 may be drawn. In this case, the IC chip 740 constituting the transmission / reception circuit is disposed in the region 700 surrounded by the inner periphery of the antenna pattern 710 and connected to the outer peripheral end 710 b of the antenna pattern 710 through the extraction electrode 730.

  Further, it is preferable to use a thermal transfer method as a method for forming an antenna pattern or a parallel resonance pattern, but the present invention is not limited to this, and other methods, for example, printing conductive ink on an insulating film. It is possible to use a method, a method of etching a metal foil laminated on an insulating film, a method of punching a metal foil tape using a mold or the like. In addition, it is not necessary to form an antenna pattern or a parallel resonance pattern by a single method. For example, an antenna pattern is formed on an insulating film as a support by an etching method, and a parallel resonance pattern is formed thereon by a thermal transfer method. It doesn't matter.

  Further, the use of the planar antenna element according to the present invention is not limited to the non-contact IC tag, and can be applied to various antenna devices.

1 is a schematic plan view showing a structure of a planar antenna element 100 according to a preferred first embodiment of the present invention. It is a schematic sectional drawing along the AA line shown in FIG. 1 is a block diagram of an antenna device using a planar antenna element 100. FIG. 3 is an equivalent circuit diagram of the planar antenna element 100. FIG. (A)-(c) is a schematic plan view which shows the example which made the parallel resonance pattern 1 to 3, respectively. It is a schematic plan view showing an example in which a parallel resonance pattern 122 is arranged at a corner 110c. In this example, the parallel resonance patterns are arranged so as to cover two adjacent straight portions, and (a) shows an example where the parallel resonance patterns 125 are arranged so as to cover the straight portions 110s ₆ , 110s ₁₀ , and (b). Shows an example in which the parallel resonance pattern 125 is arranged so as to cover the straight portions 110 s ₂ and 110 s ₆ . FIG. 5 is a schematic plan view showing a structure of a planar antenna element 200 according to a preferred second embodiment of the present invention. FIG. 6 is a schematic plan view showing a structure of a planar antenna element 300 according to a preferred third embodiment of the present invention. FIG. 10 is a schematic plan view showing the structure of a planar antenna element 400 according to a preferred fourth embodiment of the present invention. 6 is a schematic plan view showing a modification of the planar antenna element 300. FIG. 6 is a schematic plan view showing a modification of the planar antenna element 400. FIG. FIG. 10 is a schematic plan view showing the structure of a planar antenna element 500 according to a preferred fifth embodiment of the present invention. It is a schematic plan view which shows the example which has arrange | positioned the parallel resonance pattern of various variations. It is a schematic plan view which shows the example which has arrange | positioned IC chip 710 in the area | region 700 enclosed by the inner periphery of the antenna pattern.

Explanation of symbols

50 Transmission / reception circuit 100, 200, 300, 400, 500 Planar antenna element 101 Insulating film 110, 210, 310, 410, 510, 710 Antenna pattern 110a, 210a, 510a Inner edge 110b, 210b, 510b, 710b of antenna pattern Antenna pattern outer peripheral ends 110s _{1 to} 110s ₁₂ Antenna pattern straight line part 110c Antenna pattern corner parts 121 to 125, 521 to 523, 621 to 629 Parallel resonance patterns 130, 230, 330, 430, 530, 730 Lead wiring pattern 130a , 230a, 530a Inner ends 130b, 230b, 530b of the lead-out wiring pattern Outer end 190 of the lead-out wiring pattern 190 Adhesive layer 700 Area 740 surrounded by the inner periphery of the antenna pattern C chips L1, L2 short side of the long sides S1, S2 antenna pattern of the antenna pattern P1, P2 feed terminal

Claims (12)

  A spiral planar antenna pattern is separated from the antenna pattern by being provided in a layer different from the antenna pattern, and is relatively separated from a portion located on the inner peripheral side of the antenna pattern. A planar antenna element comprising: a parallel resonance pattern for capacitively coupling a portion located on the outer peripheral side. The antenna pattern is adjacent to the first part, the second part adjacent to the first part, located on the inner peripheral side when viewed from the first part, and the second part, And at least a third portion located on the inner peripheral side when viewed from the portion of 2,
2. The planar antenna element according to claim 1, wherein the parallel resonance pattern is capacitively coupled to the other two without capacitively coupling to any one of the first to third portions.   The planar antenna element according to claim 1, wherein the parallel resonance pattern is provided on a side opposite to a radiation direction of the antenna pattern.   The antenna pattern has a plurality of straight portions and a plurality of corner portions located at both ends of the straight portions, and the parallel resonance pattern is arranged at substantially the center of the straight portions. The planar antenna element as described in any one of Claims 1 thru | or 3.   5. The capacitor electrode pattern is provided on at least one of the parallel resonance pattern and the antenna pattern at a portion where the parallel resonance pattern and the antenna pattern intersect each other. The planar antenna element according to 1.   The planar type according to any one of claims 1 to 5, wherein a plurality of the parallel resonance patterns are provided, and the plurality of parallel resonance patterns are substantially uniformly distributed in a circumferential direction of the antenna pattern. Antenna element.   7. The wiring board according to claim 1, further comprising a lead-out wiring pattern in which one end is electromagnetically coupled to an inner peripheral end or an outer peripheral end of the antenna pattern, and the other end is drawn outside or inside the antenna pattern. The planar antenna element according to claim 1.   The planar antenna element according to claim 7, wherein the lead-out wiring pattern and the parallel resonance pattern are formed in the same layer.   9. The planar type according to claim 7, wherein a capacitance electrode pattern is provided on at least one of the lead-out wiring pattern and the antenna pattern at a portion where the lead-out wiring pattern and the antenna pattern intersect. Antenna element.   The planar antenna element according to any one of claims 7 to 9, wherein the parallel resonance pattern and the lead-out wiring pattern are distributed substantially uniformly in a circumferential direction of the antenna pattern.   11. The planar type according to claim 1, further comprising a support, wherein the antenna pattern and the parallel resonance pattern are attached to the support via an adhesive layer. Antenna element. Forming a spiral planar antenna pattern having a resonance frequency higher than a target resonance frequency;
Measuring the resonant frequency of the antenna pattern;
Obtaining a capacitance value necessary for adjustment based on the measured resonance frequency and the target resonance frequency;
Forming a parallel resonance pattern that capacitively couples a portion located on the relatively inner periphery side and a portion located on the relatively outer periphery side of the antenna pattern based on the capacitance value;
A method of manufacturing a planar antenna element, comprising:

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