JP2006140607A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable switching of communication without providing a component such as a mechanical switch. <P>SOLUTION: The communication apparatus comprises an antenna AN having a central frequency shifted from the communication frequency, and a finger holding portion B arranged at such a position as the central frequency of the antenna AN is varied to a communicable frequency when a finger touches the holding portion B. By switching communication by utilizing frequency characteristics (variation in the central frequency of the antenna AN) which vary as a finger approaches the antenna AN, a switching component such as a mechanical switch is eliminated and the cost is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication device used for an RFID (Radio Frequency Identification) system, for example.

  An RFID system is usually composed of a reader having a write / read function and a wireless tag. Conventionally, particularly in the microwave region, a tag with a built-in battery has been used as a wireless tag in various fields such as FA, logistics, distribution, and sales. Recently, a batteryless tag that detects a transmission radio wave from a reader and performs a tag operation using the detected radio wave as drive power has appeared.

  For example, as shown in FIG. 23, the RFID system includes a reader RW, an antenna RA, and a wireless tag T. The reader RW transmits a radio wave signal, and the radio wave signal transmitted from the reader RW is transmitted to the radio tag. The information received by T and stored in the memory in the tag is subjected to reflection modulation on the input signal and returned to the reader RW. The signal returned from the wireless tag T is demodulated by the reader RW to extract tag information. In the RFID system, frequency bands such as 13.56 MHz band, 900 MHz band, and 2.54 GHz band are used.

  As an example of a wireless tag used in an RFID system, there is a wireless tag having a dipole antenna. The wireless tag is shown in FIG.

  A radio tag T10 shown in FIG. 24 is formed by forming a dipole antenna 101 that transmits and receives a signal as a radio wave on a dielectric substrate 104 and incorporating a tag IC 103 having a tag processing function. In the RFID tag T10 having such a dipole antenna, a good gain can be obtained by setting the antenna length of the dipole antenna 101 to the half wavelength (λ / 2) of the wavelength λ of the communication frequency. Matching can be achieved relatively easily.

  As a system using a wireless tag such as an RFID tag, by associating the tag ID with an e-mail address, the ID of the wireless tag approaching an advertising tower or a radio wave poster (attached to a reader) is read, and the user owns the wireless tag There is an information providing system that transmits an advertisement to a mail address of a mobile phone (see, for example, Patent Document 1). In this system, the ID is read only when the wireless tag approaches the radio wave poster, so that the ID is read unnecessarily or an advertisement is transmitted regardless of the user's intention. There's a problem. In order to solve such a problem, it is necessary to operate the tag only when the user desires so that the wireless tag can be read (communication).

  Further, in a wireless tag used for a shoplifting prevention system or the like, when a store clerk takes out a product from a sales floor or the like, it may be necessary to temporarily stop the tag operation (tag reading).

  As described above, in a wireless tag such as an RFID tag, it has been required to add a function for switching between enabling / disabling communication according to a use or the like. There has been proposed a method of switching between enabling / disabling communication by providing a switch (see, for example, Patent Documents 2 to 5). In the shoplifting prevention system, as a method of stopping the operation of the product tag, a method of demagnetizing or demagnetizing the tag using a dedicated instrument is employed.

As another method, in a wireless tag including a resonance circuit composed of an antenna coil L and a capacitor C, when a moisture absorber is provided and the absorber absorbs moisture, the value of C of the resonance circuit is A method of switching between enabling / disabling communication by utilizing the fact that the resonance frequency shifts and changes has been proposed (see, for example, Patent Document 6).
Japanese Patent Laid-Open No. 2003-224677 JP 2003-123040 A JP 2002-254998 A JP 2000-306066 A JP 2003-069335 A JP 2004-085277 A

  By the way, in the techniques described in Patent Documents 2 to 5, it is necessary to provide a switch with a switch for switching communication between possible / impossible, and the wireless tag becomes expensive. The technique described in Patent Document 6 is a method of switching between enabling / disabling communication by absorbing moisture in the absorber, and for specific applications (liquid detection system) such as detecting paper diapers and leakage. Since this is a target technology, it cannot be applied to communication devices such as wireless tags used in general product tags and information providing systems.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication device including a wireless tag or the like capable of switching between enabling / disabling of communication without providing a component such as a switch. To do.

  The communication device of the present invention includes an antenna having a communication frequency as a center frequency and a finger holding unit, and the holding unit affects the center frequency of the antenna when a finger is attached to the holding unit. It is characterized by being provided.

  According to the communication device of the present invention, since the center frequency of the antenna is used as the communication frequency, a communicable state is maintained when the center frequency of the antenna is not affected by the finger. On the other hand, when a finger is attached to the holding portion, the finger approaches the antenna, so that the center frequency of the antenna changes. Due to this frequency change, a deviation from the communication frequency occurs and communication becomes impossible.

  As described above, in the communication device of the present invention, communication can be disabled by attaching a finger to the holding unit and approaching the antenna. Therefore, communication can be enabled / disabled without providing a switch.

  Therefore, when the communication device of the present invention is applied to, for example, the above-described system for preventing shoplifting of goods, a store clerk puts a finger on the holding part of the communication apparatus or holds the holding part with a finger when a store clerk takes out the goods from a sales floor etc. Thus, the shoplifting prevention function can be temporarily released simply by bringing the finger close to the antenna.

  The communication device of the present invention includes an antenna having a center frequency that is shifted from a communication frequency, and a finger holding unit, and the holding unit has a center frequency of the antenna when a finger is attached to the holding unit. It is characterized by being provided at a position that changes to a communicable frequency.

  According to the communication device of the present invention, the center frequency of the antenna is shifted with respect to the communication frequency. Therefore, when the center frequency of the antenna is not affected by the finger, the communication is caused by the difference between the center frequency of the antenna and the communication frequency. It becomes impossible. On the other hand, when a finger is attached to the holding portion and the finger is brought close to the antenna, the center frequency of the antenna changes to a communicable frequency, and communication is possible.

  As described above, in the communication device according to the present invention, communication can be performed by attaching a finger to the holding unit and approaching the antenna. Therefore, communication can be enabled / disabled without providing a switch.

  Therefore, when the communication device of the present invention is applied to, for example, the information providing system described above, the user approaches the radio wave poster and attaches a finger to the holding unit of the communication device or holds the holding unit with the finger, Only when they are close to each other, communication with the radio wave poster is possible, and when the user simply approaches the radio wave poster, the ID is not read and no advertisement is transmitted.

  In the communication device according to the present invention, when the electrical length (electrically effective length) of the antenna when the finger is not attached to the holding portion is longer than the electrical length when the communication is enabled, the finger is brought closer. Sometimes the electrical length of the antenna is shortened and becomes the electrical length necessary for communication, thus enabling communication. This will be described with reference to FIGS. 1 (A) and 1 (B). FIG. 1 shows an example of a dipole antenna.

  First, in the state shown in FIG. 1A, that is, when the finger is not close to the antenna AN, the electrical length (electrically effective length) is long, and the center frequency of the antenna AN is shifted from the communication frequency. Communication is disabled. At this time, the most potential difference occurs in the antenna AN at both ends of the antenna element AE. However, since the distance from the IC chip 3 to the maximum potential difference point is too long, the potential difference cannot be generated in the antenna AN.

  On the other hand, as shown in FIG. 1B, when the finger approaches the antenna AN, the finger joins both ends of the antenna AN, so that a high-frequency current flows through the finger. As a result, the impedances at both ends of the antenna AN are lowered, and the portion where the potential difference occurs most in the antenna AN is shorter than the length of the antenna element AE. That is, the distance from the IC chip 3 to the maximum potential difference point is shortened, and the center frequency of the antenna AN is increased. As a result, communication is possible with the center frequency of the antenna AN and the communication frequency matching.

  In the communication device of the present invention, if an IC chip that records a unique code (ID) is connected to an antenna, the communication device can be identified, and there are a plurality of communication devices (wireless tags). Even if it exists, it can be determined whether the communication apparatus has been operated.

  In the communication device of the present invention, a reflective element made of a conductor having the same length as the antenna or longer than the antenna may be provided between the antenna and the holding portion. By adopting such a configuration, the following effects can be achieved.

  First, in the communication device of the present invention, when there is no reflective element between the antenna and the holding part, when a finger is put on the holding part, a large amount of high-frequency current flows through the finger, so the antenna gain is reduced and the communication distance is reduced. Becomes shorter. On the other hand, if a reflective element is provided between the antenna and the holding part, a part of the high-frequency current is reflected by the reflective element to the antenna. Can be increased. As a result, a communication distance can be ensured.

  It should be noted that if the high frequency current does not flow at all to the finger, the center frequency also does not change. Therefore, it is necessary to adjust the reflection amount at the time of design. The amount of reflection can be adjusted by changing the distance between the antenna and the reflecting element.

  In the communication apparatus of the present invention, when a conductor is provided in the holding portion, the conductor acts as the above-described reflecting element. In addition, when the finger contacts the conductor, the degree of coupling between the finger and the holding portion (reflective element) becomes constant, and the degree of coupling between the antenna and the finger becomes constant. In the present invention, if the conductor is provided with sides parallel to the antenna, the antenna and the conductor are spaced at a constant interval, so that the degree of coupling between the antenna and the finger is further constant.

  In the communication device of the present invention, when a conductor is provided in a region facing the holding portion, the conductor acts as the above-described reflecting element. In addition, when the finger contacts the conductor, the degree of coupling between the finger and the holding portion (reflective element) becomes constant, and the degree of coupling between the antenna and the finger becomes constant. In the present invention, if the conductor is provided with sides parallel to the antenna, the antenna and the conductor are spaced at a constant interval, so that the degree of coupling between the antenna and the finger is further constant.

  In the communication device of the present invention, if the form of the holding part is different from other areas (for example, an opening with a finger shape combined), the user can surely recognize the holding part. In this case, if the holding portion has a button shape, the user can easily confirm the holding portion.

  In the communication apparatus of the present invention, an antenna is provided on one surface of the dielectric substrate, a holding portion made of a conductor larger than the antenna is provided on the other surface of the dielectric substrate, and the holding portion is provided on the dielectric substrate. It may be provided perpendicular to the above. Thus, the cost can be reduced by using the dielectric substrate provided with the antenna and the holding portion as separate members. That is, since a dielectric substrate having a high dielectric constant for forming an antenna is expensive, the substrate area is made as small as possible, and a holding portion that requires a certain area is a separate member from the antenna substrate (for example, a metal plate). By doing so, the apparatus cost can be reduced.

  According to the communication device of the present invention, a finger holding unit is provided in the vicinity of the antenna, and the finger is placed on the holding unit, that is, the frequency characteristics that change when the finger is brought close to the antenna (change in the center frequency of the antenna). ) Is used to switch the communicable or non-communicable state, so that it is possible to switch communicable / impossible with an inexpensive configuration without providing mechanical switches or other parts. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Example 1>
FIG. 2 is a perspective view showing an example of the communication apparatus of the present invention. FIG. 3 is a side view showing a usage state of the communication apparatus of FIG.

  The communication device S1 of this example includes an RFID tag 1 and a holding unit 5.

  The RFID tag 1 has a dielectric substrate (for example, a glass epoxy substrate) 4, and an antenna (dipole antenna) 2 including a pair of antenna elements 2 a and 2 a is formed on one surface (front surface) of the dielectric substrate 4. Yes. An RFID IC chip 3 is connected to the feeding point of the antenna 2. The antenna elements 2a and 2a are made longer than when operating as a normal tag (communication is possible), and the center frequency of the antenna 2 is set lower than the communication frequency when the finger is not approaching the antenna 2 Has been. The length between both ends of the antenna elements 2a, 2a is set to a dimension shorter than the thickness of the finger (1 to 2 cm).

  The holding part 5 is made of a metal plate larger than the antenna 2. The holding part 5 is provided perpendicularly to the RFID tag 1 on the back side of the RFID tag 1 and can hold the holding part 5 with a thumb and forefinger as shown in FIG.

  In the communication device S1 having the above structure, as shown in FIGS. 4 and 6, when the finger is not approaching the antenna 2, the antenna elements 2a and 2a are long and the center frequency of the antenna 2 is communicated. Since the frequency is lower than the frequency, the communication is disabled (the tag is not operated). At this time, in the antenna 2, the most potential difference occurs at both ends of the antenna elements 2 a and 2 a, but the distance from the IC chip 3 to the maximum potential difference point is too long to cause a potential difference in the antenna 2. .

  On the other hand, as shown in FIGS. 5 and 7, when the holding unit 5 is gripped by the thumb and the index finger, the finger approaches the antenna 2 and the fingers join both ends of the antenna 2. Flowing. As a result, the impedance at both ends of the antenna 2 is lowered, and the portion where the potential difference occurs most in the antenna 2 becomes shorter than the length of the antenna elements 2a and 2a (see FIG. 1). That is, the distance from the IC chip 3 to the maximum potential difference point is shortened, and the center frequency of the antenna 2 is increased. As a result, communication is possible with the center frequency of the antenna 2 matching the communication frequency. Therefore, the user can feel as if communication is possible by pressing the switch by simply holding the holding unit 5 with a finger.

<Example 2>
FIG. 8 is a plan view showing another example of the communication apparatus of the present invention.

  The communication device S2 of this example is characterized in that an antenna (dipole antenna) 12, an RFID IC chip 3 and a holding unit 15 are formed on a single dielectric substrate. The holding unit 15 is provided at a position where the finger approaches the antenna 12 when the finger is attached to the holding unit 15 (a position where the center frequency of the antenna 12 can be shifted to the communication frequency). . In addition, the holding unit 15 is subjected to processing such that the holding region (contact position of the finger) becomes clear by printing or the like.

  Also in this example, the antenna elements 12a and 12a are made longer than when operating as a normal tag (communication is possible), and the center frequency of the antenna 12 is not reached when the finger is not approaching the antenna 12. Is set lower than the communication frequency, so that when the finger approaches the antenna 12, the center frequency of the antenna 12 becomes higher, and the center frequency of the antenna 12 matches the communication frequency, thereby enabling communication.

<Example 3>
FIG. 9 is a plan view showing another example of the communication apparatus of the present invention.

  The communication device S3 of this example is characterized in that a reflection element (conductor) 16 having the same length as the antenna 12 is provided between the antenna 12 and the holding unit 15 in the communication device S2 of FIG. . Providing the reflective element 16 in this way has the following advantages.

  First, as in the example of FIG. 8, when there is no reflective element between the antenna 12 and the holding unit 15, a large amount of high-frequency current flows through the finger when the finger is attached to the holding unit 15. Decreases and communication distance becomes shorter. On the other hand, if the reflective element 16 is provided between the antenna 12 and the holding portion 15 as in this example, a part of the high-frequency current is reflected by the reflective element 16 toward the antenna 12, so that The high frequency current flowing through the finger by the amount of reflection can be reduced, and the gain can be increased. As a result, a communication distance can be ensured. Thus, the communication state (communication distance etc.) can be improved at low cost only by providing the reflective element 16.

  If no high-frequency current flows through the finger, the center frequency of the antenna 12 does not change, so that the amount of reflection needs to be adjusted at the design time. The amount of reflection can be adjusted by changing the distance between the antenna 12 and the reflection element 16.

<Example 4>
FIG. 10 is a plan view showing another example of the communication apparatus of the present invention.

  The communication device S4 of this example is configured such that the reflection element 16 and the holding unit 15 of the communication device S3 illustrated in FIG. A feature resides in that the metal pattern 17 is provided with sides parallel to the metal pattern 17. When such a configuration is adopted, since the degree of coupling between the finger and the holding unit 15 when the finger approaches the holding unit 15 is stabilized, the amount of change in the center frequency of the antenna 12 is stabilized.

  For example, as shown in FIG. 11, when the holding unit 15 is not configured with a metal pattern (FIG. 11A), the degree of coupling between the antenna 12 and the finger changes depending on the position of the finger with respect to the antenna 12. However, as shown in FIG. 11B, when the holding portion 15 is configured by the metal pattern 17, the antenna 12 and the holding portion 15 (metal pattern 17) are coupled, and the antenna 12 and the finger pass through the holding portion 15. As a result, the degree of coupling becomes stable. That is, since the distance between the antenna 12 and the metal pattern 17 is constant, even if the contact position of the finger with the metal pattern 17 is not constant, the change in the coupling degree can be reduced. As a result, the coupling degree is stabilized. FIG. 11 shows the communication devices S2 and S3 shown in FIG. 8 or 10 molded with resin.

<Example 5>
FIG. 12 is a plan view showing another example of the communication apparatus of the present invention. FIG. 13 is a cross-sectional view schematically showing the structure of the communication device.

  The communication device S5 of this example is obtained by molding the communication device S4 of FIG. 10 with resin, opening a part of the mold resin 20, and providing an opening 20a in a portion corresponding to the holding unit 15. There is a feature. Thus, if the opening part 20a is provided in the part corresponding to the holding | maintenance part 15, a user can recognize the holding | maintenance part 15 reliably.

  Further, when such an opening 20a is provided, as shown in FIG. 14, if the opening 20b is shaped to match the shape of the finger, the contact position of the finger is stabilized. Further, as shown in FIG. 15, when an opening 20c is provided in a portion corresponding to the holding portion 15, and a dummy button 21 made of a conductor is provided in the opening 20c, the user recognizes the holding portion 15. In addition to being easy to do, the finger contact position is stabilized.

<Example 6>
FIG. 16 is a longitudinal sectional view schematically showing another example of the communication apparatus of the present invention.

  The communication device S6 of this example is formed by molding the communication device S4 of FIG. 10 with resin, and providing a contact pattern (conductor) 18 parallel to the metal pattern 17 on the upper surface of the mold resin 20, and The contact pattern 18 has a rectangular shape, and the contact pattern 18 has a side parallel to the antenna 12.

  If the contact pattern 18 is provided in this manner, the antenna 12 and the metal pattern 17 are combined, and further, the metal pattern 17 and the metal contact pattern 18 are combined. They are connected via the contact pattern 18. As a result, the degree of coupling becomes stable.

  Further, when such a contact pattern is provided, as shown in FIG. 17, if the contact pattern 28 is circular and the contact pattern 28 is clarified by printing or the like, the contact pattern 28 is easily recognized. The finger contact position is stabilized.

<Example 7>
FIG. 18 is a longitudinal sectional view schematically showing another example of the communication apparatus of the present invention.

  The communication device S7 in this example is formed by molding the communication device S4 of FIG. 10 with resin, and the contact pattern 18 parallel to the metal pattern 17 is provided on the surface layer portion of the mold resin 20, and the contact pattern 18 is characterized in that an opening 20d for defining the contact position of the finger is provided in the upper mold resin 20.

<Example 8>
19 to 22 are plan views showing still another example of the communication apparatus of the present invention.

  The communication device S8 in FIG. 19 can reduce the size of the antenna 22 by providing meander line-shaped (bent-shaped) antenna elements 22a and 22a in place of the linear antenna element in the communication device S4 in FIG. There is a feature in the point.

  The communication device S9 of FIG. 20 is characterized in that, in the communication device S8 of FIG. 19, one of the pair of antenna elements (meander line shape) 22a constituting the antenna 22 is shared by the metal pattern 27.

  The communication device S10 of FIG. 21 is characterized in that the antenna 32 is configured by block-shaped antenna elements 32a and 32a in place of the planar pattern antenna element in the communication device S4 of FIG.

  The communication device 11 of FIG. 22 is characterized in that, in the communication device S10 of FIG. 21, one of the pair of antenna elements 32a constituting the antenna 32 is also used as the metal pattern 37.

  Here, in the above-described embodiment, the communication device that enables communication when the finger is attached to the holding unit and the finger is brought close to the antenna has been described. However, the present invention is not limited to this, and the finger is applied to the holding unit. When the finger is close to the antenna, communication may be disabled.

  In this case, the length of the antenna element when the finger is not approaching is set to the same length as when operating as a normal tag (communication possible), so that the center frequency of the antenna matches the communication frequency, When a finger is attached to the holding portion (when the finger approaches the antenna), the center frequency of the antenna is increased so as to be shifted from the communication frequency and communication is disabled.

  The present invention can be effectively used when constructing an RFID system in various fields such as FA, logistics, distribution, sales, and information providing systems.

It is operation | movement explanatory drawing of the communication apparatus of this invention. It is a perspective view which shows an example of the communication apparatus of this invention. It is a side view which shows the use condition of the communication apparatus of FIG. FIG. 3 is an operation explanatory diagram of the communication device of FIG. 2. FIG. 3 is an operation explanatory diagram of the communication device of FIG. 2. FIG. 3 is an operation explanatory diagram of the communication device of FIG. 2. FIG. 3 is an operation explanatory diagram of the communication device of FIG. 2. It is a top view which shows the other example of the communication apparatus of this invention. It is a top view which shows another example of the communication apparatus of this invention. It is a top view which shows another example of the communication apparatus of this invention. It is action | operation explanatory drawing of the communication apparatus of FIG. It is a top view which shows another example of the communication apparatus of this invention. It is sectional drawing which shows the structure of the communication apparatus of FIG. 12 typically. It is sectional drawing which shows another example of the communication apparatus of this invention typically. It is sectional drawing which shows another example of the communication apparatus of this invention typically. It is sectional drawing which shows another example of the communication apparatus of this invention typically. It is a top view which shows another example of the communication apparatus of this invention. It is sectional drawing which shows another example of the communication apparatus of this invention typically. It is a top view which shows another example of the communication apparatus of this invention. It is a top view which shows another example of the communication apparatus of this invention. It is a top view which shows another example of the communication apparatus of this invention. It is a top view which shows another example of the communication apparatus of this invention. 1 is a diagram illustrating a basic configuration of an RFID system. It is a top view which shows an example of the conventional communication apparatus (wireless tag).

Explanation of symbols

S1 to S11 Communication device 1 RFID tag 2, 12 Antenna 2a, 12a Antenna element 3 IC chip (for RFID)
4,14 Dielectric substrate 5,15 Holding part 16 Reflective element 17 Metal pattern (conductor)
18 Contact pattern (conductor)
20 Mold resin 20a-20d Opening 21 Dummy button

Claims (11)

  An antenna having a communication frequency as a center frequency, and a finger holding unit, and the holding unit is provided at a position that affects the center frequency of the antenna when a finger is attached to the holding unit. A communication device.   An antenna having a frequency shifted from the communication frequency as a center frequency and a finger holding unit, and the holding unit changes the center frequency of the antenna to a communicable frequency when the finger is attached to the holding unit. A communication device provided at a position.   3. The communication device according to claim 2, wherein the antenna is set such that an electrical length when a finger is not attached to the holding portion is longer than an electrical length when a communication is possible. A communication device.   4. The communication apparatus according to claim 3, wherein an IC chip is connected to the antenna.   5. The communication device according to claim 1, wherein a reflective element made of a conductor having a length equal to or longer than the length of the antenna is provided between the antenna and the holding portion. A communication device.   The communication apparatus according to claim 1, wherein a conductor is provided in the holding portion.   The communication device according to claim 1, wherein a conductor is provided in a region facing the holding portion.   8. The communication apparatus according to claim 6, wherein the conductor includes a side parallel to the antenna.   The communication apparatus according to any one of claims 1 to 4, wherein a form of the holding unit is different from other areas.   The communication apparatus according to claim 9, wherein the holding unit is button-shaped. 3. The communication device according to claim 1, wherein the antenna is provided on one surface of the dielectric substrate, and a holding portion made of a conductor larger than the antenna is provided on the other surface of the dielectric substrate. And the holding unit is provided perpendicular to the dielectric substrate.

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