JP2010252003A - Proximity communication reader / writer device - Google Patents

Abstract

When an IC tag is brought into contact with an antenna portion of a reader / writer device, communication may not be possible due to a dielectric of the antenna portion.
Processing the IC tag, increasing the output of the reader / writer, or changing the cover material of the antenna unit of the reader / writer in order to communicate in a contact state, such as strength, workability, environmental friendliness, radio wave interference, etc. Satisfying the conditions is not easy.
The contact area between the IC tag and the cover of the antenna unit is reduced by providing unevenness smaller than the IC tag on the cover of the antenna unit of the reader / writer device. That is, the wavelength shortening effect of the radio signal of the IC tag and the reader / writer device is reduced, and the shift of the resonance frequency is suppressed. This enables stable communication even in the proximity state.
[Selection] Figure 3

Description

  The present invention relates to an antenna unit of a reader / writer device that performs wireless communication with an IC tag.

  The IC tag transmits / receives data to / from the reader / writer device by electromagnetic waves or the like. Since the characteristics of an IC tag vary depending on the object to which the IC tag is to be attached, an IC tag having special characteristics according to the intended use is required. For example, a metal tag corresponding to a metal is known. . (Patent Document 1).

  Further, since IC tag communication is a technique characterized by non-contact wireless communication, the antenna unit of the reader / writer device and the IC tag are kept in a certain distance and are used without contact. In recent years, however, the use of slip-type IC tags placed on the antenna portion of the reader / writer device, that is, in contact or in close proximity to that is increasing. (Patent Document 2).

JP 2008-90813 A JP 2008-139922 A

  However, placing the IC tag on the antenna unit of the reader / writer device, that is, using it in contact or close proximity, means that the IC tag is attached to the antenna unit of the reader / writer device in consideration of the characteristics of the IC tag. That means the same thing. An IC tag changes its antenna characteristics typified by the resonance frequency due to the nearby dielectric, so communication is possible when it is about 1 cm away from the antenna part of the reader / writer device, but communication is made when it is in contact. There are times when you cannot.

  In Patent Document 1, the characteristics of the IC tag are improved, but this is intended to improve the IC tag in accordance with the characteristics of a patch, and the influence on the antenna unit of the reader / writer device is taken into consideration. However, in this technique, satisfactory performance is often not obtained due to the influence of the antenna unit of the reader / writer device.

  On the other hand, when supporting with a reader / writer device, the housing material of the antenna part that contacts the IC tag can be handled by using a material having a dielectric constant that does not affect communication, but the condition is satisfied and the strength, It is not easy to satisfy various conditions such as processability and environmental compatibility.

  In addition, the communication performance is improved by increasing the power emitted from the reader / writer device, but the high-output reader / writer device, that is, the parts used are large-sized, expensive, and responding to increased heat generation. Therefore, it is not preferable because it is necessary to increase the size of the reader / writer device and to induce radio wave interference.

  The problem to be solved by the present invention is that there is no special processing on the IC tag, and no special material is used for the reader / writer device, and the output is not increased. Is to improve the communication performance at the time.

  The present invention reduces the contact area between the IC tag and the cover of the antenna unit by providing the cover of the antenna unit of the reader / writer device with irregularities smaller than the IC tag. In other words, by reducing the effect of shortening the wavelength of the radio signal between the IC tag and the reader / writer device and suppressing the shift of the resonance frequency, stable communication can be performed even when the IC tag is in contact or close to the IC tag. To do.

  In addition, in order to obtain the same effect, a sheet having the concavo-convex shape is added to the antenna portion of the reader / writer device, so that stable communication is possible even when the IC tag is in contact with or in proximity to the IC tag.

  In the present invention, communication of the IC tag in a contact state is realized by devising the cover shape of the antenna portion of the reader / writer device.

It is sectional drawing of the antenna part of the conventional reader / writer apparatus. It is a top view of the antenna part of the conventional reader / writer apparatus. It is sectional drawing of the antenna part of the reader / writer apparatus of this invention. It is sectional drawing to which the uneven structure of this invention was expanded. It is a top view of the antenna part of the reader / writer apparatus of this invention. It is the figure which showed the communication success result of the IC tag.

  The purpose of performing stable communication in contact with the cover of the antenna unit of the reader / writer device and the IC tag or in a close proximity corresponding to the IC tag is realized by grooving the cover surface.

  FIG. 1 is a cross-sectional view showing a structure of an antenna portion of a conventional reader / writer device, wherein 101 is an antenna and 102 is a cover. FIG. 2 is a plan view showing the structure of the antenna unit of the conventional reader / writer device, and 101 and 102 are the same as those in FIG.

  The antenna 101 is made of iron, and the cover 102 is made of acrylonitrile butadiene styrene (hereinafter referred to as ABS) resin. These are general antenna materials and cover materials. The cover 102 has a shape that covers the upper surface and the four side surfaces of the antenna 101. The cover 102 has a material thickness of 2.5 mm and is a distance of 20.0 mm from the antenna 101. The above is only one example, and it is obvious that the same effect can be obtained even when other materials and dimensions are applied.

  The radio wave emitted from the antenna 101 passes through the cover 102 and communicates with the IC tag ahead. In the first embodiment, the radio wave from the antenna 101 is emitted in the upper surface direction and passes through the upper surface of the cover 102. Here, the upper surface of the cover 102 is a radio wave emission surface.

  In general, the wavelength shortening effect of a radio wave passing through a dielectric is obtained by the following formula 1.

  Since the relative permittivity ε of the ABS resin is about 3, the wavelength is shortened to about 0.6 times that in air. The IC tag is designed when the IC tag is brought into contact with the cover 102 due to the effect of shortening the wavelength and the change in the antenna characteristics of the IC tag due to the contact with the ABS resin and the proximity environment according to the effect. Will not operate at the specified frequency, resulting in poor communication.

  Here, when the antenna of the IC tag is a half-wave dipole, the antenna length L of the IC tag is λ / 2 (wavelength λ), and only the length L1 is in contact with the casing (relative permittivity ε = 3). L2 (= L−L1) is considered as non-contact (relative permittivity = 1).

  If only the L1 portion receives the wavelength shortening effect and the L2 portion does not have the wavelength shortening effect, the equivalent length L3 after the wavelength shortening in the entire antenna of the IC tag is expressed by the following Equation 2.

  Further, the equivalent length L4 after wavelength shortening when the entire antenna of the IC tag is in contact with the cover is expressed by the following Equation 3.

  Subtracting Equation 3 from Equation 2 yields Equation 4 below.

  Equation 4 can be regarded as a reduction in the wavelength shortening effect according to the present embodiment with respect to the influence of the wavelength shortening effect when the IC tag antenna and the cover are in full contact with each other, that is, in the known technology. Can do.

  That is, it can be seen that the wavelength shortening effect determined by Equation 4 can be reduced by providing irregularities and grooves on the cover surface, for example. In this embodiment, by providing irregularities and grooves on the cover surface, the resonance frequency due to the wavelength shortening effect that cannot be avoided in the use and application forms of the IC tag, such as reading by bringing the IC tag into contact with the reader / writer surface. Can be reduced and the reading performance of the IC tag can be improved.

  Hereinafter, the embodiment will be described with reference to FIGS. 3, 4, and 5.

  FIG. 3 is a cross-sectional view showing the structure of the antenna portion of the reader / writer device of the present embodiment, wherein 101 is an antenna, and 103 is an uneven cover. The antenna and the cover are arranged substantially in parallel, and the side without the antenna in the antenna cover is the radio wave emission surface.

  FIG. 4 is an enlarged view of the uneven shape of the uneven processing cover 103.

  FIG. 5 is a plan view showing the structure of the antenna unit of the reader / writer device of the present embodiment. 101 and 103 are the same as those in FIG.

  The antenna 101 is not modified at all. The concavo-convex processed cover 103 is formed by processing the concavo-convex groove 104 on the radio wave emission surface (upper surface) of the cover 102 to form an concavo-convex shape.

  The concave / convex groove 104 can reduce the contact portion with the IC tag, and the opening portion of the concave / convex portion 104 and the convex portion formed therefrom are smaller than the IC tag, so that the IC tag is stable. Can be placed.

  FIG. 6 is a diagram showing the effect of the first embodiment. Communication sometimes failed when the distance between the IC tag and the cover 102 was 0 mm (contact) to 4 mm. When the cover 102 is changed to the concavo-convex processing cover 103, it can be seen that communication can be stably performed from 0 mm. It can also be confirmed that the stable communication is possible even at 10 mm, which was originally stable, and there is no adverse effect. In this verification, it can be understood that the communication performance under the contact with the IC tag or a similar environment according to the IC tag is improved without any additional processing to the IC tag and without increasing the output of the reader / writer device.

  As described above, in this embodiment, it is possible to obtain an effect without changing the material used for the cover of the antenna unit of the reader / writer device, and further, no change is made to the output. There is no adverse effect such as an increase. Therefore, it is possible to improve the communication performance when the reader / writer device contacts the IC tag without affecting the price and size of the reader / writer device.

  In this embodiment, reading can be performed by bringing an IC tag into contact with an antenna portion of a reader / writer device.

101 Antenna 102 Cover 103 Concavity and convexity processing cover 104 Concavity and convexity groove

Claims (1)

In a reader / writer device for proximity communication that performs wireless communication with an IC tag,
An antenna unit communicating with the IC tag;
Having a cover between the antenna part and the IC tag,
Proximity communication-compatible reader / writer device having a concave portion having an opening smaller than that of the IC tag on a radio wave emission surface of the cover

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