JP7328841B2 - RFID tag reader - Google Patents

Description

An embodiment of the present invention relates to a wireless tag reader.

2. Description of the Related Art Conventionally, there is known a technique for detecting whether a wireless tag has passed through a gate in a wireless tag reader. In such a wireless tag reader, wireless tags outside the gate are not to be read. Therefore, it is necessary to prevent the wireless tag outside the gate from being read. That is, it is necessary to prevent radio waves from leaking out of the gate.

However, gates are provided with entrances and exits for people, goods, and the like. As a result, radio waves may leak out from the entrance/exit of the gate. As a result, the wireless tag reader may read wireless tags outside the gate.

A problem to be solved by the present invention is to provide a wireless tag reader capable of reducing leaked radio waves.

A wireless tag reader according to an embodiment includes a tunnel, an antenna, and an opening. The antenna radiates radio waves for reading wireless tags into the tunnel. The opening is provided in the tunnel so as to penetrate to the inside of the tunnel, and is smaller than the wavelength of the radio waves radiated by the antenna.

FIG. 1 is a perspective view showing an example of the appearance of the wireless tag reader according to this embodiment. FIG. 2 is a front cross-sectional view showing an example of the appearance of the wireless tag reader according to this embodiment. FIG. 3 is a diagram showing an example of the top surface of the wireless tag reader according to this embodiment. FIG. 4 is a diagram showing an example of a slot that emits radio waves having directivity. FIG. 5 is a diagram showing an example of a transmission area of radio waves radiated from the wireless tag reader. FIG. 6 is a side cross-sectional view showing an example of the appearance of the wireless tag reader according to this embodiment. FIG. 7 is a diagram showing an example of the arrangement of slots according to this embodiment. FIG. 8 is a diagram showing an example of the arrangement of slots according to this embodiment.

Hereinafter, embodiments of the wireless tag reader will be described in detail with reference to the accompanying drawings. The embodiment described below is one embodiment of the wireless tag reader, and does not limit its configuration, specifications, and the like. The wireless tag reader of this embodiment is an application example of a wireless tag reader that reads wireless tags for inventory control when entering or leaving a warehouse.

FIG. 1 is a perspective view showing an example of the appearance of a wireless tag reader 1 according to this embodiment. FIG. 2 is a front cross-sectional view showing an example of the appearance of the wireless tag reader 1 according to this embodiment.

The radio tag reader 1 has a tunnel 10 . Tunnel 10 comprises a first side 11 , a second side 12 and a top surface 13 . The first side surface 11 is arranged at a position facing the second side surface 12 . Also, the first side surface 11 and the second side surface 12 are erected substantially perpendicular to the ground. The first side surface 11 and the second side surface 12 support the upper surface 13 . Top surface 13 forms the ceiling of tunnel 10 .

Between the first side surface 11 and the second side surface 12, a passage is formed through which a trolley or the like carrying an article with a wireless tag passes. Thus, the wireless tag reader 1 has a passage inside the tunnel 10 . An operator of the wireless tag reader 1 pushes the trolley on which the article with the wireless tag is placed to pass through the inside of the tunnel 10 . The wireless tag reader 1 reads the wireless tag when the wireless tag passes through the tunnel 10 .

Here, the wireless tag is a tag such as an RF (Radio Frequency) tag. A wireless tag comprises an IC (Integrated Circuit) chip for storing information and an antenna. The wireless tag executes reading and writing of information stored in the IC chip through wireless communication with the wireless tag reader 1 . The wireless tag transmits information to the wireless tag reader 1 when the information stored in the IC chip is read. For example, a wireless tag contains article information that can identify an article to which the device is attached.

The RFID tag reader 1 includes a first antenna 21 , a second antenna 22 , a third antenna 23 and a fourth antenna 24 inside the tunnel 10 . The first antenna 21 is installed on the first side surface 11 substantially at the center of the tunnel 10 in the transport direction in which articles are placed on carts and transported, and below the center of the tunnel 10 in the height direction. The second antenna 22 is installed in the upper portion of the first side surface 11 at substantially the center of the tunnel 10 in the transport direction in which articles are placed on carts and transported. The third antenna 23 is installed on the second side surface 12 substantially at the center of the tunnel 10 in the transport direction in which articles are placed on carts and transported, and below the center of the tunnel 10 in the height direction. The fourth antenna 24 is installed at the upper portion of the second side surface 12 at substantially the center of the tunnel 10 in the transport direction in which articles are placed on carts and transported.

The first antenna 21 , the second antenna 22 , the third antenna 23 , and the fourth antenna 24 radiate radio waves for reading wireless tags into the tunnel 10 . Also, the first antenna 21, the second antenna 22, the third antenna 23, and the fourth antenna 24 receive radio waves having article information output from the wireless tags. Hereinafter, the first antenna 21, the second antenna 22, the third antenna 23, and the fourth antenna 24 are referred to as antennas 20 when not distinguished from each other.

Here, when the antennas 20 radiate radio waves at the same time, the radio waves radiated from the antennas 20 interfere with each other, and the reading of the wireless tag may fail. Therefore, one of the antennas 20 radiates radio waves by time division. In this embodiment, a case where the wireless tag reader 1 has four antennas 20 will be described as an example. However, the number of antennas 20 may be five or more, or may be three or less.

The wireless tag reader 1 also includes a closing portion (not shown) that closes the entrance/exit of the tunnel 10 . The closing part is, for example, a door that closes the entrance of the tunnel 10 . If the tunnel 10 has both an entrance and an exit, the closure will close both the entrance and the exit. The closing portion is formed of a radio wave shielding material that shields radio waves emitted by the antenna 20 . For example, the closing part is a shield mesh made of metal that shields radio waves. The closing portion is not limited to the shield mesh, and may be a metal plate with holes or other members that shield radio waves.

By the way, the tunnel 10 has an entrance/exit for a trolley in which articles with wireless tags are placed. Therefore, radio waves may leak from the doorway. The wireless tag reader 1 may read wireless tags attached to articles outside the wireless tag reader 1 due to radio waves leaking from the doorway. Therefore, it is necessary to reduce the amount of radio waves leaking from the doorway.

Therefore, the tunnel 10 is provided with a slot 30 (see FIG. 3) for leaking radio waves. The tunnel 10 emits part of the radio waves emitted by the first antenna 21, the second antenna 22, the third antenna 23, and the fourth antenna 24 from the slot 30, thereby reducing radio waves leaking from the entrance of the tunnel 10. are doing.

For example, tunnel 10 includes slot 30 in top surface 13 of tunnel 10 . FIG. 3 is a diagram showing an example of the upper surface 13 of the wireless tag reader 1 according to this embodiment. As shown in FIG. 3, tunnel 10 includes one or more slots 30 in top surface 13 . That is, slot 30 is provided in the ceiling of tunnel 10 .

The slot 30 is provided so as to penetrate the tunnel 10 to the inside of the tunnel 10 , and is an opening smaller than the wavelength of the radio waves radiated by the antenna 20 . One or more slots 30 emit radio waves. Since the slot 30 for emitting the radio wave radiated from the antenna 20 is provided in this way, the radio tag reader 1 can reduce the radio wave that leaks from the entrance/exit.

Here, the wireless tag reader 1 may erroneously read wireless tags outside the wireless tag reader 1 due to radio waves emitted from the slot 30 . In order to prevent such misreading, the slot 30 emits directional radio waves. By emitting radio waves having directivity, it is possible to assume a region where radio waves emitted from the slot 30 read wireless tags. By preventing the wireless tag from entering the assumed area, the wireless tag reader 1 is prevented from reading the wireless tag by mistake.

Further, as shown in FIG. 3, when the upper surface 13 of the tunnel 10 is provided with a slot 30, radio waves are emitted upward from the upper surface 13. As shown in FIG. It is difficult to imagine that an article with a wireless tag attached will be placed above the upper surface 13 . Therefore, it is possible to prevent the wireless tag reader 1 from erroneously reading the wireless tag. The orientation of the slot 30 in the longitudinal direction shown in FIG. 3 is an example and may be changed arbitrarily. That is, the longitudinal direction of the slot 30 is not limited to substantially parallel to the Y-axis direction, but may be substantially parallel to the X-axis direction, or directed to form an angle with the Y-axis or the X-axis. may

Here, the slot 30 emits radio waves having directivity due to the shape of the slot 30 . FIG. 4 is a diagram showing an example of a slot 30 that emits radio waves having directivity. The length of the slot 30 in the longitudinal direction is expressed by Equation (1) below.
λ/20 ≤ length of slot 30 in longitudinal direction ≤ λ (Formula 1)
λ: Wavelength of radio waves emitted by the antenna

The slot 30 shown in FIG. 4 is rectangular in shape. However, the shape of the slot 30 is not limited to a rectangle as long as the above conditions are satisfied. For example, the shape of the slot 30 may be a rectangular shape with rounded corners, or other shapes.

The length of the slot 30 in the longitudinal direction is equal to or greater than 1/20 of the wavelength of radio waves and equal to or less than the wavelength. Furthermore, it is preferable that the length of the slot 30 in the longitudinal direction is a length that easily resonates with radio waves having a wavelength of λ/2, λ/4, or λ/8. Also, the length of the slot 30 in the lateral direction is arbitrary, but is preferably 1 mm or more, for example. With such a shape, the slot 30 emits radio waves having directivity.

Here, FIG. 5 is a diagram showing an example of transmission regions R1 and R2 of radio waves radiated from the wireless tag reader 1. As shown in FIG. As shown in FIG. 5, when the slot 30 is not provided in the tunnel 10, the wireless tag reader 1 forms a radio wave transmission region R1. On the other hand, by providing the slot 30 in the upper surface 13 of the tunnel 10, the RFID tag reader 1 forms a radio wave transmission area R2 in which the area of radio waves leaking from the entrance/exit of the tunnel 10 is reduced. Since radio waves are emitted from the slot 30 in this manner, the wireless tag reader 1 forms a transmission area R2 that is narrower than the transmission area R1. Therefore, the wireless tag reader 1 can reduce radio waves emitted from the entrance/exit of the tunnel 10 more than when the slot 30 is not provided.

The wireless tag reader 1 also includes a radio wave absorber (not shown) outside the slot 30 that absorbs radio waves radiated by the antenna 20 . The radio wave absorber is, for example, a magnetic material such as a ferrite sheet. By covering the outside of the slot 30 with a radio wave absorber, the radio wave absorber absorbs radio waves emitted from the slot 30 . Therefore, the radio wave absorber can prevent the wireless tag outside the tunnel 10 from being read.

The tunnel 10 may also be provided with slots 30 in the first side 11 and the second side 12 as well as the top surface 13 . FIG. 6 is a side sectional view showing an example of the appearance of the wireless tag reader 1 according to this embodiment. As shown in FIG. 6, the first side surface 11 is provided with a slot 30 . The orientation of the slot 30 in the longitudinal direction shown in FIG. 6 is an example and may be changed arbitrarily. That is, the longitudinal direction of the slot 30 is not limited to substantially parallel to the Y-axis direction, but may be substantially parallel to the X-axis direction, or directed to form an angle with the Y-axis or the X-axis. may

Here, FIG. 7 is a diagram showing an example of the arrangement of the slots 30 according to this embodiment. As shown in FIG. 7, the first side 11 has a first antenna 21 and a plurality of slots 30 . The interval between the slots 30 is a quarter of the wavelength of radio waves emitted by the first antenna 21 . Thus, by setting the interval between the slots 30 to λ/4 wavelength, the phase emitted from each slot 30 is shifted by 90 degrees. Then, the radio waves emitted from the slot 30 are superimposed with radio waves whose phases are shifted by 90 degrees. As a result, the intensity of radio waves emitted from the slot 30 to the inside of the wireless tag reader 1 is increased. Therefore, the wireless tag reader 1 can improve the accuracy of reading wireless tags. In addition, in FIG. 7, the case of the first antenna 21 has been described as an example. The second antenna 22, the third antenna 23, and the fourth antenna 24 are also the same.

Also, if there is no slot 30 , radio waves radiated from the antenna 20 may become surface waves propagating on the surface of the first side surface 11 and be emitted from the entrance/exit of the tunnel 10 . On the other hand, as shown in FIG. 6, since the surface wave is emitted from the slot 30 by providing the slot 30, the emission from the entrance/exit of the tunnel 10 can be reduced. In this case, the radio waves radiated from the entrance/exit of the tunnel 10 can be reduced by setting the distance from the antenna 20 to the slot 30 to be equal to or greater than the wavelength λ/4 of the radio waves radiated by the antenna 20 .

Further, by setting the interval between the slots 30 to λ/2 of the wavelength of the radio wave emitted by the antenna 20, it is possible to reduce the possibility of erroneously reading the wireless tag outside the wireless tag reader 1. can. Here, FIG. 8 is a diagram showing an example of the arrangement of the slots 30 according to this embodiment. As shown in FIG. 8, the interval between the slots 30 is half the wavelength of the radio waves. Thus, by setting the interval between the slots 30 to 1/2 of the wavelength, the phases emitted from each slot 30 are shifted by 180 degrees. Then, the radio waves emitted from the slot 30 are superimposed with radio waves whose phases are shifted by 90 degrees. As a result, the radio waves emitted from the slot 30 cancel each other out. Therefore, the wireless tag reader 1 can reduce erroneous reading of wireless tags outside the wireless tag reader 1 . In addition, in FIG. 8, the case of the first antenna 21 has been described as an example. The second antenna 22, the third antenna 23, and the fourth antenna 24 are also the same.

As described above, the RFID tag reader 1 according to this embodiment includes the slot 30 that emits part of the radio waves emitted by the antenna 20 to the outside of the tunnel 10 . As a result, the wireless tag reader 1 can reduce radio waves leaking from the tunnel 10 .

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

Further, in the above embodiment, the wireless tag reader 1 that can be put into the tunnel 10 by the operator pushing the trolley on which the article with the wireless tag is placed has been described as an example. However, the wireless tag reader 1 may be placed inside the tunnel 10 by conveying the article with the wireless tag by a belt conveyor or the like.

1 RFID tag reader 10 Tunnel 11 First side 12 Second side 13 Top surface 20 Antenna 21 First antenna 22 Second antenna 23 Third antenna 24 Fourth antenna 30 Slot R1, R2 Transmission area

JP-A-2006-72672

Claims (5)

tunnel and
An antenna that is placed inside the tunnel and radiates radio waves for reading wireless tags into the tunnel;
an opening that is provided in the tunnel so as to penetrate to the inside of the tunnel and that emits the radio waves inside the tunnel to the outside of the tunnel and that is smaller than the wavelength of the radio waves radiated by the antenna;
A wireless tag reader. The opening is provided in the ceiling of the tunnel,
The wireless tag reader according to claim 1. The length of the opening in the longitudinal direction is 1/20 or more of the wavelength of the radio wave and is equal to or less than the wavelength.
The wireless tag reader according to claim 1 or 2. A radio wave absorber for absorbing the radio waves radiated by the antenna is provided outside the tunnel at the opening;
The wireless tag reader according to any one of claims 1 to 3. The distance between the openings is half the wavelength of the radio waves,
The wireless tag reader according to any one of claims 1 to 4.

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