Boost antenna, communication equipment

Abstract

When the boost antenna is positioned to be movable relative to the IC tag, the communication distance between the IC tag and the reader / writer can be extended. [Solution] One aspect of the present invention is a boost antenna positioned to be movable relative to an IC tag. This boost antenna has an antenna pattern including a loop portion and is configured to electromagnetically couple with the IC tag when the loop portion is in a first position facing the IC tag.

Description

Technical Field

[0001] The present invention relates to a technique for extending the communication distance with an IC tag.

Background Art

[0002] With the spread of inventory management and sales management of products using RFID (Radio Frequency Identification), IC tags having an antenna and an IC (Integrated Circuit) chip electrically connected to the antenna are widely used. Information recorded on the IC tag is read by non-contact communication between the reader / writer and the IC tag and used for various purposes.

[0003] By the way, in an RFID system, the communication distance between the reader / writer and the IC tag may be several centimeters depending on the frequency band used. Therefore, depending on the application field, it is desirable to be able to extend the communication distance. Thus, it is known to provide a booster antenna between the IC tag and the reader / writer to extend the communication distance. For example, in Patent Document 1, on the substantially central axis in the space where the antenna of the reader and the antenna of the RFID tag face each other, a booster antenna tuned to the carrier frequency used in the RFID tag system is arranged facing the antenna of the reader in front of the RFID tag.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional boost antennas are fixedly positioned relative to the target IC tag (for example, the IC tag to be read) and are assumed to operate on that IC tag at all times. In other words, the possibility of the boost antenna being movable has not been considered in conventional designs.

[0006] Therefore, the present invention aims to extend the communication distance between an IC tag and a reader / writer when the boost antenna is positioned to be movable relative to the IC tag. [Means for solving the problem]

[0007] One aspect of the present invention is a boost antenna positioned to be movable relative to an IC tag, having an antenna pattern including a loop portion, and electromagnetically coupling with the IC tag when the loop portion is in a first position facing the IC tag. [Effects of the Invention]

[0008] According to one aspect of the present invention, the communication distance between the IC tag and the reader / writer can be extended when the boost antenna is positioned to be movable relative to the IC tag. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the relationship between a boost antenna and an IC tag in one embodiment. [Figure 2] This diagram illustrates the antenna pattern of the boost antenna shown in Figure 1. [Figure 3] This figure shows a modified version of the antenna pattern of a boost antenna. [Figure 4] This is a perspective view showing a communication device and a reader / writer communicating according to one embodiment. [Figure 5] Figure 4 is a front view of the fixed and movable members included in the communication device shown. [Figure 6]This figure shows the case where the movable member is in two different positions relative to the fixed member in the communication device shown in Figure 4. [Figure 7] This diagram shows a modified example of a boost antenna installed on a movable member. [Figure 8] This is a front view of a fixed member and a movable member included in a communication device of another embodiment. [Figure 9] This figure shows the case where the movable member is in two different positions relative to the fixed member in the communication device shown in Figure 8. [Figure 10] This is a front view of a fixed member and a movable member included in a communication device of yet another embodiment. [Figure 11] This figure shows the case in the communication device shown in Figure 10 where the movable member is in two different positions relative to the fixed member. [Figure 12] This is a perspective view showing a communication situation between a communication device and a reader / writer in a different embodiment than that shown in Figure 4. [Figure 13] Figure 12 is a front view of the fixed and movable members included in the communication device shown. [Figure 14] This figure shows the case where the movable member is in two different positions relative to the fixed member in the communication device shown in Figure 12. [Modes for carrying out the invention]

[0010] The forms described below are not limited to those shown in the brief description of the drawings.

[0011] A first aspect of one aspect of the present invention is a boost antenna positioned to be movable relative to an IC tag, having an antenna pattern including a loop portion, and electromagnetically coupling with the IC tag when the loop portion is in a first position facing the IC tag.

[0012] According to a first aspect of a certain embodiment of the present invention, the communication distance between the IC tag and the reader / writer can be extended when the boost antenna is positioned to be movable relative to the IC tag.

[0013] A second aspect of an embodiment of the present invention is the boost antenna according to the first aspect, wherein the antenna pattern is configured such that the degree of electromagnetic coupling with the IC tag is greater at the first position than when the loop portion is in a second position where the loop portion does not face the IC tag.

[0014] According to a second aspect of an embodiment of the present invention, since the degree of coupling is increased at the first position, the communication distance can be extended more effectively.

[0015] A third aspect of an embodiment of the present invention is a tag having an IC chip and a tag antenna including a loop portion connected to the IC chip, wherein the loop portion of the antenna pattern electromagnetically couples with the loop portion of the tag antenna when in the first position, which is the boost antenna according to the first or second aspect.

[0016] According to a third aspect of an embodiment of the present invention, the communication distance can be effectively extended by electromagnetic coupling with the loop portion of the IC tag.

[0017] A fourth aspect of an embodiment of the present invention is the boost antenna according to any one of the first to third aspects, wherein the antenna pattern has a meander portion connected to the loop portion of the antenna pattern.

[0018] According to a fourth aspect of an embodiment of the present invention, the antenna pattern can be miniaturized while configuring the antenna pattern to obtain desired antenna characteristics.

[0019] A fifth aspect of an embodiment of the present invention is the boost antenna according to the fourth aspect, wherein the meander portion is formed to widen as it moves away from the loop portion of the antenna pattern.

[0020] According to a fifth aspect of a certain embodiment of the present invention, the antenna pattern can be tapered toward its tip, and the tip of the antenna pattern can be effectively electromagnetically coupled with the IC tag.

[0021] A sixth aspect of a certain embodiment of the present invention is a boost antenna according to any one of the first to fifth embodiments, wherein the antenna pattern is formed of a linear conductor having a first end and a second end as open ends.

[0022] According to a sixth aspect of a certain embodiment of the present invention, since the antenna pattern is formed from a conductor, there is a high degree of design freedom for the antenna pattern.

[0023] A seventh aspect of a certain embodiment of the present invention is the boost antenna according to the sixth aspect, wherein the loop portion of the antenna pattern is provided with the linear conductor wound around it at least once.

[0024] According to a seventh aspect of a certain embodiment of the present invention, a loop can be formed by winding a linear conductor.

[0025] An eighth aspect of a certain embodiment of the present invention is a boost antenna according to any one of the fourth to seventh embodiments, wherein the antenna pattern is formed of a linear conductor having a first end and a second end as open ends, and the meander portion is provided on at least one side of the first end or the second end with respect to the loop portion of the antenna pattern.

[0026] According to an eighth aspect of a certain embodiment of the present invention, an antenna pattern can be effectively formed in a limited area using a linear conductor.

[0027] A ninth aspect of a certain embodiment of the present invention is a boost antenna according to any one of the fourth to seventh embodiments, wherein the antenna pattern is formed of a linear conductor having a first end and a second end as open ends, and the meander portion is provided on both the first end side and the second end side with respect to the loop portion of the antenna pattern.

[0028] According to a ninth aspect of a certain embodiment of the present invention, an antenna pattern can be effectively formed in a limited area using a linear conductor.

[0029] A tenth aspect of a certain embodiment of the present invention is a boost antenna according to any one of the first to ninth embodiments, wherein the boost antenna is made of conductive thread.

[0030] According to a tenth aspect of a certain embodiment of the present invention, antenna patterns can be manufactured with high precision.

[0031] An eleventh aspect of a certain embodiment of the present invention is a communication device comprising an IC tag and a boost antenna positioned to be movable relative to the IC tag, wherein the boost antenna has an antenna pattern including a loop portion, and the boost antenna electromagnetically couples with the IC tag when the loop portion is in a first position facing the IC tag.

[0032] According to an eleventh aspect of a certain embodiment of the present invention, the communication distance between the IC tag and the reader / writer can be extended when the boost antenna is positioned to be movable relative to the IC tag.

[0033] A twelfth aspect of a certain embodiment of the present invention is a communication device according to the eleventh aspect, wherein the boost antenna is configured such that the movement trajectory of the portion other than the tip does not overlap with the IC tag.

[0034] According to a twelfth aspect of a certain embodiment of the present invention, when the boost antenna is in a position other than the first position, it is possible to suppress electromagnetic coupling of the portion of the antenna pattern other than the tip portion with the IC tag.

[0035] A thirteenth aspect of a certain embodiment of the present invention is a communication device according to the eleventh or twelfth embodiment, wherein the IC tag is a tag having an IC chip and a tag antenna connected to the IC chip and including a loop portion, wherein the loop portion of the antenna pattern is electromagnetically coupled to the loop portion of the tag antenna when it is in the first position.

[0036] According to a thirteenth aspect of a certain embodiment of the present invention, the communication distance can be effectively extended by electromagnetic coupling with the loop portion of the IC tag.

[0037] The embodiments will be described in detail below with reference to the drawings. In one embodiment, the boost antenna is positioned between the IC tag and the reader / writer and is configured to extend the communication distance between the IC tag and the reader / writer. Figure 1 shows the positional relationship between the boost antenna 5 and the IC tag TG in one embodiment. The boost antenna 5 is configured to be able to move relative to the IC tag TG. In one embodiment, the IC tag TG is fixed. In specific application examples, the boost antenna 5 and the IC tag TG can be mounted on a member that allows them to move relative to each other. Here, the mode of motion when the boost antenna 5 moves is not limited; it may be rotational motion, linear motion, zigzag motion, or motion along any curve.

[0038] As shown in Figure 1, in one embodiment, the boost antenna 5 can take on two positions as a result of relative movement with respect to the IC tag TG: one where the tip TP of the antenna pattern 50 (see also Figure 2) faces the IC tag TG (an example of a first position), and another where the tip TP of the antenna pattern 50 does not face the IC tag TG (an example of a second position). The distance between the tip TP of the boost antenna 5 and the IC tag TG when the two are facing each other should be such that mutual induction occurs between the boost antenna 5 and the tag antenna included in the IC tag TG. In one embodiment, as shown in an enlarged view in Figure 1, the IC tag TG includes an IC chip 11 and a tag antenna 12 connected to the IC chip 11, which includes a loop portion. The loop portion of the tag antenna 12 may be spiral in shape.

[0039] In one embodiment, the antenna pattern 50 is configured such that the degree of electromagnetic coupling with the IC tag TG is greater when the tip TP faces the IC tag TG (first position in Figure 1) than when the tip TP does not face the IC tag TG (second position in Figure 1). The degree of electromagnetic coupling is represented, for example, by a coupling coefficient based on the respective inductances of the tip TP of the antenna pattern 50 and the IC tag TG. By increasing the degree of electromagnetic coupling with the IC tag TG, the communication distance can be extended more effectively.

[0040] As shown in Figure 1, the boost antenna 5, which is movable relative to the IC tag TG, is configured to extend or not extend the communication distance between the IC tag TG and the reader / writer (not shown) depending on the position of the boost antenna 5. In other words, depending on the position of the boost antenna 5, it is possible to set whether or not data can be read from the IC tag TG. Therefore, as will be described later, it can be widely used for applications that detect the position (or state) of an object using an IC tag.

[0041] Figure 2 is a diagram that further illustrates the antenna pattern 50 exemplified in Figure 1, and shows an enlarged view of the antenna pattern 50 in Figure 1. As shown in Figure 2, the antenna pattern 50 is composed of, for example, a linear conductor and has a tapered tip TP. The tip TP includes a loop 5L. When the loop 5L is positioned opposite the IC tag TG, the boost antenna 5 is electromagnetically coupled to the IC tag TG. The loop 5L is provided with the linear conductor wound at least once or more times. The degree of coupling can be increased by electromagnetic coupling between the loop portion 5L and the loop portion of the tag antenna 12. From the viewpoint of fully utilizing the effect of electromagnetic induction, it is preferable that the diameter of the loop portion 5L is equal to or greater than the diameter of the loop portion of the tag antenna 12. The antenna length of the antenna pattern 50, excluding the loop section 5L, is set so that resonance is obtained at the carrier frequency of the IC tag (for example, 860-920 MHz in the UHF band).

[0042] The antenna pattern 50 has a meander section 5M connected to the loop section 5L. More specifically, in Figure 2, the antenna pattern 50 is formed of a linear conductor having a first end 51 and a second end 52 as open ends, and the meander section 5M is provided on the second end 52 side with respect to the loop section 5L. By providing the meander section 5M, the antenna pattern 50 can be miniaturized while being configured to obtain the desired antenna characteristics. The antenna pattern 50 in Figure 2 is merely an example; the meander section may be provided on the first end 51 side with respect to the loop section 5L, or it may be provided on both the first end 51 side and the second end 52 side.

[0043] From another perspective, the antenna pattern 50 has a first straight section 53 and a second straight section 54 that extend linearly from the tip section TP at an acute angle. The meander section 5M is connected to the second straight section 54 and is located between the first straight section 53 and the second straight section 54. The meander section 5M is formed to widen as it moves away from the loop section 5L of the antenna pattern 50.

[0044] The tapered shape of the tip TP is a shape in which the width tapers in a certain direction (to the right in Figure 2). From another perspective, the tapered shape of the tip TP is a shape in which the distance between the first straight section 53 and the second straight section 54 narrows in a certain direction (to the right in Figure 2). In one embodiment, the first straight section 53 extending in a certain direction (to the right in Figure 2) folds back, and the second straight section 54 extends in the opposite direction (to the left in Figure 2). The tip TP may be rounded or pointed, as shown in Figure 2. If the tip TP is pointed, the loop portion will not be annular as shown in Figure 2.

[0045] Since the antenna pattern 50 tapers towards the tip TP, the portion of the antenna pattern 50 other than the tip TP can be placed in a limited area. As will be described later, by placing the portion other than the tip TP in a limited area, it is possible to suppress the unintentional electromagnetic coupling between the portion other than the tip TP and the IC tag. In the antenna pattern 50, the portion other than the tip TP is the portion that does not include the loop portion 5L. In the antenna pattern 50 shown in Figure 2, the portion other than the tip TP includes the meander portion 5M, at least a part of the first straight portion 53, and at least a part of the second straight portion 54.

[0046] Instead of the antenna pattern 50 shown in Figure 2, a different antenna pattern can be used for the boost antenna 5. Figure 3 shows modified antenna patterns 50A to 50C. In Figure 3, antenna pattern 50A differs from antenna pattern 50 in that it has a loop portion at the tip TP but does not have a meander portion. Antenna pattern 50B, like antenna pattern 50A, does not have a meander section, but differs from antenna pattern 50A in that it has a capacitor 58. Regardless of the shape of the antenna pattern, the antenna characteristics can be adjusted by adding a reactance component such as a capacitor to the conductor forming the antenna pattern. Antenna pattern 50C differs from antenna pattern 50 in that its tip TP has a folded shape 56 instead of a loop. As long as it can electromagnetically couple with the IC tag, the tip TP of the antenna pattern does not have to include a loop, as in antenna pattern 50C. The folded shape 56 of antenna pattern 50C may be a rounded U-shape as shown in Figure 3, or a pointed V-shape.

[0047] Antenna patterns 50A to 50C all have a rounded tip (TP), but this is not mandatory, and the tip (TP) may be sharp. In that case, the sharp tip (TP) may be folded over rather than looped. In the antenna patterns 50 in Figure 2 and 50C in Figure 3, the meander section is formed on only one side relative to the tip TP, but this is not limited to that. The meander section may be formed on both sides relative to the tip TP.

[0048] Next, an example of the application of the boost antenna 5 will be explained with reference to Figures 4 to 6. Figure 4 is a perspective view showing the communication between a communication device 1, which includes a boost antenna 5 and an IC tag TG, and a reader / writer 9 in one application example. In the application example shown in Figure 4, the communication device 1 includes a fixed member 2 (an example of a first member) and a movable member 3 (an example of a second member). The fixed member 2 and the movable member 3 are preferably made of an insulator such as resin so as not to interfere with communication. One or more arbitrary numbers of IC tags TG (seven in the example in Figure 4) are placed on the fixed member 2. The movable member 3 is capable of rotational movement along the surface of the fixed member 2 around the rotation axis 91. A boost antenna 5 (an example of a first antenna) is placed on the movable member 3. The configuration allows the boost antenna 5 to move relative to the IC tags TG placed on the fixed member 2 as the movable member 3 rotates. The reader / writer 9 transmits radio waves to read and write data to the IC tags TG.

[0049] Figure 5 is a front view of the fixed member 2 and movable member 3 included in the communication device 1 shown in Figure 4. As shown in Figure 5, the fixing member 2 has a circular opening 22 through which the rotating shaft 91 (Figure 4) passes. IC tags TG-10 to TG-70 are arranged on the tag mounting surface 21 of the fixing member 2 in an arc with respect to the center of the opening 22. The IC tags TG-10 to TG-70 are arranged at predetermined intervals. In the following explanation, when referring to matters common to IC tags TG-** (where "**" is a number used to distinguish IC tags), the term "IC tag TG" will be used as appropriate.

[0050] As shown in Figure 5, the movable member 3 has a circular opening 32 for connecting to the rotating shaft 91 (Figure 4). To connect the movable member 3 and the rotating shaft 91, for example, the rotating shaft 91 is press-fitted into the opening 32. The method of connecting the movable member 3 and the rotating shaft 91 is not limited to press-fitting; other methods such as screw fastening can also be used. A boost antenna 5 is positioned on the antenna mounting surface 31 of the movable member 3. The antenna pattern 50 of the boost antenna 5 shown in Figure 5 is the same as that shown in Figure 2. The distance from the center of the opening 32 to the center of the loop portion 5L is approximately equal to the distance from the center of the opening 22 of the fixed member 2 to the center of each IC tag TG. The movable member 3 has a projection 33, and the loop portion 5L is positioned on the antenna mounting surface 31 corresponding to the projection 33.

[0051] As the fixed member 2 rotates around the rotation axis 91, the loop portion 5L of the boost antenna 5 may face any of the IC tags TG-10 to TG-70, which are positioned at different locations. From another perspective, the configuration is such that the loop portion 5L alternates between positions where it faces an IC tag and positions where it does not face an IC tag. Each IC tag TG-10, TG-20, TG-30, TG-40, TG-50, TG-60, and TG-70 stores data indicating the rotational position of the movable member 3 when the loop portion 5L of the boost antenna 5 is facing each other (these positions are P10, P20, P30, P40, P50, P60, and P70 respectively, in a counterclockwise direction). Here, the rotational position of the movable member 3 corresponds to the direction in which the projection 33 of the movable member 3 faces.

[0052] The operation of the communication device 1 will be explained below with reference to Figure 6. Figure 6 shows the case in the communication device 1 shown in Figure 4, where the movable member 3 is in two different positions P40 and P35 relative to the fixed member 2 when viewed from the front. In Figure 6, position P40 (an example of the first position) is the position of the movable member 3 when the loop portion 5L of the boost antenna 5, which is located on the movable member 3, is facing (overlapping in a front view with) the IC tag TG-40. In Figure 6, position P35 (an example of the second position) is the position when the movable member 3 has rotated slightly clockwise from position P40, and the movable member 3 is located between position P30 and position P40. At position P35, the loop portion 5L is not facing (overlapping in a front view with) either IC tag TG.

[0053] When the movable member 3 is at position P40, when the reader / writer 9 transmits a radio wave, only the response signal from the IC tag TG-40 is amplified by the boost antenna 5 and becomes readable. Therefore, the reader / writer 9 can recognize that the movable member 3 is at position P40 based on the data contained in the response signal from the IC tag TG-40. On the other hand, when the movable member 3 is at position P35, when the reader / writer 9 transmits a radio wave, neither the response signal from the IC tag TG is amplified by the boost antenna 5. Therefore, the reader / writer 9 cannot obtain information about the position of the movable member 3.

[0054] Similarly, when the movable member 3 is positioned such that the loop portion 5L of the boost antenna 5 faces each of the IC tags TG-10 to TG-70, the reader / writer 9 can receive data indicating the position corresponding to each IC tag TG. Therefore, when the movable member 3 moves to any of the positions P10, P20, P30, P40, P50, P60, or P70, information about the position of the movable member 3 can be obtained.

[0055] In one embodiment, the antenna pattern 50 of the boost antenna 5 is configured such that the movement trajectory of the portion other than the tip TP does not overlap with the IC tag TG. That is, as can be seen from Figure 6, as the movable member 3 rotates, the tip TP (the portion including the loop 5L) of the antenna pattern 50 may or may not face the IC tag TG, but the portion other than the tip TP is configured not to face the IC tag TG. This is for the following reasons.

[0056] For example, if, when the movable member 3 is at position P40 (Figure 6), a portion of the antenna pattern 50 other than the tip TP is positioned to overlap with a nearby IC tag TG-30 or IC tag TG-50, then some degree of electromagnetic coupling may occur between the portion other than the tip TP and the IC tag TG-30 or IC tag TG-50. In that case, even though the movable member 3 is at position P40, it may be mistakenly detected as being at position P30 or P50. Furthermore, if, when the movable member 3 is at position P35 (Figure 6), a portion of the antenna pattern 50 other than the tip TP is positioned to overlap with a nearby IC tag TG-30 or IC tag TG-40, then some degree of electromagnetic coupling may occur between the portion other than the tip TP and the IC tag TG-30 or IC tag TG-40. In that case, it may be possible to mistakenly detect that the movable member 3 is at position P30 or P40. To prevent such false detections, the antenna pattern 50 is configured such that the movement trajectory of the portion other than the tip TP does not overlap with the IC tag TG. For this purpose, it is preferable to make the entire antenna pattern 50 tapered toward the tip TP, thereby generating a highly coupled electromagnetic connection between the boost antenna 5 and the IC tag TG only when the tip TP is facing one of the IC tags TG.

[0057] In one embodiment, the antenna pattern is made of conductive threads to enable high-precision manufacturing. Figure 7 shows an antenna pattern 50E made of conductive threads. The antenna pattern 50E is formed by sewing conductive thread to the fabric portion 35. As the conductive thread, for example, a copper-plated material with a fibrous core such as aramid fiber can be used. The fabric portion 35 on which the antenna pattern 50E is formed is bonded to the antenna mounting surface 31 with adhesive.

[0058] Next, two modified examples of the communication device 1 shown in Figure 4 will be described with reference to Figures 8 to 11. Figures 8 and 9 relate to the first modified example, and Figures 10 and 11 relate to the second modified example. As mentioned above, in the communication device 1 shown in Figure 4, information about the position of the movable member 3 can be obtained when the movable member 3 moves to any of the positions P10, P20, P30, P40, P50, P60, or P70. In contrast, these modified examples are configured to detect the position of the movable member 3 when it is in any of the following positions in addition to positions P10, P20, P30, P40, P50, P60, and P70: position P15 between position P10 and position P20, position P25 between position P20 and position P30, position P35 between position P30 and position P40, position P45 between position P40 and position P50, position P55 between position P50 and position P60, and position P65 between position P60 and position P70.

[0059] First, with reference to Figure 8, the first modified example will be explained. In the first modified example, IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 (each an example of a second IC tag) are arranged on the tag mounting surface 21 of the fixing member 2 in an arc with respect to the center of the opening 22, in addition to IC tags TG-10 to TG-70. Each of the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 stores data indicating the position of the movable member 3 when the loop portion 5L of the boost antenna 5 is facing it (positions P15, P25, P35, P45, P55, and P65, respectively). The distance from the center C2 of the aperture 22 to IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 is shorter than the distance from the center C2 to IC tags TG-10, TG-20, TG-30, TG-40, TG-50, TG-60, and TG-70.

[0060] In one embodiment, the movable member 3F is constructed by connecting a second movable member 36 (an example of a third member) to a movable member 3 (Figure 5) using, for example, an adhesive, and is able to move in conjunction with it. The movable member 3F may also be constructed with the movable member 3 and the second movable member 36 as a single integrated member. A common opening 32 is formed in the movable member 3 and the second movable member 36. A boost antenna 13 (an example of a second antenna) having an antenna pattern including a loop portion 13L and a meander portion 13M is formed on the antenna mounting surface of the second movable member 36. The boost antenna 13 is provided to extend the communication distance of each IC tag by electromagnetic coupling when the loop portion 13L faces each of the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65. The distance from the center of the opening 32 to the center of the loop portion 13L is approximately equal to the distance from the center of the opening 22 of the fixed member 2 to the center of the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65.

[0061] Referring to Figure 9, the operation of the first modified version of the communication device is as follows. Figure 9 shows the first modified example, where the movable member 3F is in two different positions P40 and P35 relative to the fixed member 2 when viewed from the front.

[0062] When the movable member 3F is at position P40, when the reader / writer 9 transmits a radio wave, only the response signal from the IC tag TG-40 is amplified by the boost antenna 5 and becomes readable. Therefore, the reader / writer 9 can recognize that the movable member 3F is at position P40 based on the data contained in the response signal from the IC tag TG-40. At this time, the loop portion 13L of the boost antenna 13 positioned on the movable member 3F is not facing any IC tag. On the other hand, when the movable member 3F is at position P35 (an example of the second position), the loop portion 5L does not face any IC tag, but the loop portion 13L faces the IC tag TG-35 and electromagnetically couples with it. Therefore, when radio waves are transmitted by the reader / writer 9, only the response signal from the IC tag TG-35 is amplified by the boost antenna 5 and becomes readable. As a result, the reader / writer 9 can recognize that the movable member 3F is at position P35 based on the data contained in the response signal from the IC tag TG-35.

[0063] As described above, either the loop portion 5L of the boost antenna 5 or the loop portion 13L of the boost antenna 13 electromagnetically couples with any IC tag placed on the fixed member 2. In this way, the boost antenna 5 and the boost antenna 13 perform complementary operations, allowing information about the position of the movable member 3F to be acquired when the movable member 3F moves to any of the positions P10, P15, P20, P25, P30, P35, P40, P45, P50, P55, P60, P65, or P70.

[0064] Next, a second modified example will be described with reference to Figure 10. In the second modified example, IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 (each an example of a second IC tag) are arranged on the tag mounting surface 21 of the fixing member 2 in an arc with respect to the center of the opening 22, in addition to IC tags TG-10 to TG-70. Each of the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 stores data indicating the position of the movable member 3G when the loop portion 5L of the boost antenna 5 is facing it (positions P15, P25, P35, P45, P55, and P65, respectively). In the example shown in Figure 10, the distance from the center C2 of the opening 22 to the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 is the same as the distance from the center C2 to the IC tags TG-10 to TG-70, but this is not always the case.

[0065] On the antenna mounting surface 31G of the movable member 3G, a boost antenna 15 (an example of a second antenna) is positioned substantially point-symmetric to the boost antenna 5 with respect to the center of the opening 32 (i.e., substantially opposite the boost antenna 5 with respect to the center of the opening 32). Figure 10 shows the case where the antenna pattern of the boost antenna 15 is the same as the antenna pattern of the boost antenna 5, but this is not the case as they operate separately as will be described later. In one embodiment, the boost antenna 15 has an antenna pattern that includes a loop portion 15L and a meander portion 15M. The boost antenna 15 is provided to extend the communication range of each IC tag TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65 by electromagnetic coupling when the loop portion 15L faces each of the IC tags. The distance from the center of the opening 32 to the center of the loop portion 15L is approximately equal to the distance from the center of the opening 22 of the fixing member 2 to the center of the IC tags TG-15, TG-25, TG-35, TG-45, TG-55, and TG-65.

[0066] Referring to Figure 11, the operation of the second modified version of the communication device is as follows: Figure 11 shows a communication device according to the second modified example, in which the movable member 3G is at two different positions P40 and P35 relative to the fixed member 2 when viewed from the front.

[0067] When the movable member 3G is at position P40, when the reader / writer 9 transmits a radio wave, only the response signal from the IC tag TG-40 is amplified by the boost antenna 5 and becomes readable. Therefore, the reader / writer 9 can recognize that the movable member 3G is at position P40 based on the data contained in the response signal from the IC tag TG-40. At this time, the loop portion 15L of the boost antenna 15 positioned on the movable member 3G is not facing any IC tag. On the other hand, when the movable member 3G is at position P35 (an example of a second position), the loop portion 5L does not face any IC tag, but the loop portion 15L faces the IC tag TG-35 and electromagnetically couples with it. Therefore, when radio waves are transmitted by the reader / writer 9, only the response signal from the IC tag TG-35 is amplified by the boost antenna 5 and becomes readable. As a result, the reader / writer 9 can recognize that the movable member 3G is at position P35 based on the data contained in the response signal from the IC tag TG-35.

[0068] As described above, either the loop portion 5L of the boost antenna 5 or the loop portion 15L of the boost antenna 15 electromagnetically couples with any IC tag placed on the fixed member 2. In this way, the boost antenna 5 and the boost antenna 15 perform complementary operations, so that when the movable member 3G moves to any of the positions P10, P15, P20, P25, P30, P35, P40, P45, P50, P55, P60, P65, or P70, information about the position of the movable member 3G can be obtained.

[0069] The communication device 1 (Figure 4) described above, as well as the first and second modifications, are all configured so that the movable member performs rotational motion. In contrast, the following description will focus on a communication device configured so that the movable member performs linear motion, with reference to Figures 12 to 14. Figure 12 is a perspective view showing a communication situation between a communication device 1A, which includes a boost antenna 8 and an IC tag TG, and a reader / writer 9, in a different application example than that shown in Figure 4. In the application example shown in Figure 12, the communication device 1A includes a fixed member 6 (an example of a first member) and a movable member 7 (an example of a second member). The fixed member 6 and the movable member 7 are preferably made of an insulator such as resin so as not to interfere with communication. One or any number of IC tags TG (five in the example in Figure 12) are placed on the fixing member 6. The fixing member 6 has a support base 61 and a columnar portion 62 supported by the support base 61. The columnar portion 62 extends upward from the support base 61. The movable member 7 is mounted on the columnar portion 62 so as to be slidable in the vertical direction, and a boost antenna 8 (an example of a first antenna) is positioned on it. The boost antenna 8 is configured to move relative to the IC tag TG placed on the fixed member 6 as the movable member 7 moves in a linear vertical direction. The reader / writer 9 transmits radio waves to read and write data to the IC tag TG.

[0070] Figure 13 is a front view of the fixed member 6 and the movable member 7 included in the communication device 1A shown in Figure 12. As shown in Figure 13, IC tags TG-10 to TG-50 are arranged in a straight line at equal intervals from the bottom up on the columnar portion 62 of the fixing member 6. A boost antenna 8 is positioned on the antenna mounting surface 71 of the movable member 7. In one embodiment, the antenna pattern of the boost antenna 8 is formed by a linear conductor having a first end 81 and a second end 82 as open ends, and has a loop portion 8L and a pair of meander portions 8M. Each meander portion 8M is provided on both sides of the first end 81 and the second end 82 with respect to the loop portion 8L. In one embodiment, each of the pair of meander portions 8M extends in a direction perpendicular to the direction in which the IC tags TG-10 to TG-50 are positioned (up and down direction) (i.e., horizontal direction).

[0071] As the movable member 7 moves linearly up and down, the loop portion 8L of the boost antenna 8 may face any of the IC tags TG-10 to TG-50, which are positioned at different locations. From another perspective, as the movable member 7 moves linearly up and down, the configuration is such that the loop portion 8L alternates between a position where it faces an IC tag and a position where it does not face an IC tag. Each of the IC tags TG-10, TG-20, TG-30, TG-40, and TG-50 stores data indicating the position of the movable member 7 (positions P10, P20, P30, P40, and P50, respectively) when the loop portion 8L of the boost antenna 8 is facing each other.

[0072] The operation of communication device 1A will be explained below with reference to Figure 14. Figure 14 shows the case in the communication device 1A shown in Figure 12, where the movable member 7 is in two different positions P10 and P40 relative to the fixed member 6 when viewed from the front. In Figure 14, position P10 is the position of the movable member 7 when the loop portion 8L of the boost antenna 8, which is located on the movable member 7, is facing (overlapping in a front view with) the IC tag TG-10. In Figure 14, position P40 is the position of the movable member 7 when it is facing the IC tag TG-40.

[0073] When the movable member 7 is at positions P10 and P40, when the reader / writer 9 transmits radio waves, only the response signals from IC tags TG-10 and TG-40, respectively, are amplified by the boost antenna 8 and become readable. Therefore, the reader / writer 9 can recognize that the movable member 7 is at positions P10 and P40 based on the data contained in the response signals from IC tags TG-10 and TG-40. On the other hand, when the movable member 7 is in a position where the loop portion 8L does not face either IC tag, when the reader / writer 9 transmits radio waves, the response signals from either IC tag TG are not amplified by the boost antenna 8. Therefore, the reader / writer 9 cannot obtain information about the position of the movable member 7.

[0074] Similarly, when the movable member 7 is positioned such that the loop portion 8L of the boost antenna 8 faces each of the IC tags TG-10 to TG-50, the reader / writer 9 can receive data indicating the position corresponding to each IC tag TG. Therefore, the reader / writer 9 can acquire position information of the movable member 7 when it moves to any of the positions P10, P20, P30, P40, or P50. The communication device 1A can be used, for example, as a water level gauge to detect the water level. That is, by installing the fixed member 6 in the water and configuring the movable member 7 to move up and down in response to fluctuations in the water level, the water level (position of the movable member 7) can be determined based on the data received by the reader / writer 9 from one of the IC tags.

[0075] In one embodiment, the antenna pattern of the boost antenna 8 is configured such that the movement trajectory of the portion other than the loop portion 8L does not overlap with the IC tag. That is, as can be seen from Figure 14, as the movable member 7 moves linearly, the loop portion 8L of the antenna pattern may or may not face the IC tag TG, but the portion other than the loop portion 8L (meander portion 8M, etc.) is configured so that it does not face the IC tag TG. In the antenna pattern of the boost antenna 8, the meander portion 8M extends in a direction perpendicular to the direction in which the IC tags TG-10 to TG-50 are positioned (up and down direction) (i.e., the horizontal direction), so the meander portion 8M does not unintentionally face the IC tag, and erroneous detection of the position of the movable member 7 can be prevented.

[0076] Although embodiments of the boost antenna and communication device of the present invention have been described above, the present invention is not limited to the above embodiments. Furthermore, the above embodiments can be improved or modified in various ways without departing from the spirit of the present invention. For example, in one embodiment, the antenna pattern is composed of antenna strips rather than linear conductors. [Explanation of symbols]

[0077] 1,1A…Communication device 2… Fixing member 21... Tag installation surface 22…Aperture 3, 3F, 3G... Movable parts 31,31G… Antenna mounting surface 32…Aperture 33...Protrusion 35... Fabric 36…Second movable member 5…Boost antenna 50, 50A, 50B, 50C… Antenna patterns TP…Tip 51,81...1st end, 52,82...2nd end 53...First straight section, 54...Second straight section 56…Folded shape 58…Capacitor 5M...Meanda Department 5L... Loop section 6… Fixing member 61...Support stand 62...Columnar part 7…Movable parts 71… Antenna mounting surface 8... Boost antenna 8M...Meanda Department 8L... Loop section 9... Reader / Writer 13, 15… Boost antenna 13M, 15M... Meanda section 13L, 15L... Loop section 91... Rotation axis TG…IC tag 11…IC chip 12…Tag Antenna

Claims

1. A boost antenna positioned to be movable relative to the IC tag, Having an antenna pattern that includes a loop section, The loop portion electromagnetically couples with the IC tag when it is in a first position facing the IC tag. Boost antenna.

2. The antenna pattern is configured such that the degree of electromagnetic coupling with the IC tag is greater at the first position than when the loop portion is in a second position where it does not face the IC tag. The boost antenna described in claim 1.

3. The IC tag is a tag having an IC chip and a tag antenna connected to the IC chip and including a loop portion, The loop portion of the antenna pattern is electromagnetically coupled with the loop portion of the tag antenna when it is in the first position. A boost antenna as described in claim 1.

4. The antenna pattern has a meander portion connected to the loop portion of the antenna pattern. A boost antenna as described in any one of claims 1 to 3.

5. The meander portion is formed to widen as it moves away from the loop portion of the antenna pattern. The boost antenna described in claim 4.

6. The antenna pattern is formed by a linear conductor having a first end and a second end as open ends. A boost antenna as described in any one of claims 1 to 3.

7. The loop portion of the antenna pattern is provided with the linear conductor wound around it at least once. The boost antenna described in claim 6.

8. The antenna pattern is formed by a linear conductor having a first end and a second end as open ends. The meander portion is provided on at least one side of the first end or the second end of the antenna pattern, with reference to the loop portion. Boost antenna as described in claim 4 or 5

9. The antenna pattern is formed by a linear conductor having a first end and a second end as open ends. The meander portion is provided on both the first end and the second end sides with respect to the loop portion of the antenna pattern. The boost antenna described in claim 4.

10. The boost antenna is made of conductive thread. A boost antenna as described in claim 1.

11. A communication device comprising an IC tag and a boost antenna positioned to be movable relative to the IC tag, The boost antenna has an antenna pattern including a loop section. The boost antenna electromagnetically couples with the IC tag when the loop portion is in a first position facing the IC tag. Communication device.

12. The boost antenna is configured such that the movement trajectory of the portion other than the tip does not overlap with the IC tag. A communication device as described in claim 11.

13. The IC tag is a tag having an IC chip and a tag antenna connected to the IC chip and including a loop portion, The loop portion of the antenna pattern is electromagnetically coupled with the loop portion of the tag antenna when it is in the first position. A communication device according to claim 11 or 12.

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