JP2020187653A - Tag reading system - Google Patents

Abstract

To provide a technique for improving reading performance of an RF tag attached to an article moving along a conveyance path.SOLUTION: A tag reading system may include a position detection section, a directivity variable antenna, a tag reading section, and a control section. The position detection section detects a position of an article in a work section set on a conveyance path for conveying the article. The tag reading section reads information from an RF tag attached to the article via a directivity variable antenna for irradiating the work section with a radio wave. The control section changes a direction of a beam of the directivity variable antenna along the conveyance path according to the position of the article detected by the position detection section, and changes transmission and reception conditions of the tag reading section so that an erroneous reading rate by the tag reading section decreases as the direction of the beam approaches an entrance of the work section.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a technique for reading an RF tag attached to an article transported along a predetermined transport path.

There is known a tag reading system that reads information on RF tags attached to each article by using a reader / writer provided in a transport path for transporting the articles. RF is an abbreviation for Radio Frequency.

Patent Document 1 discloses a technique of using a plurality of antennas having strong directivity and changing the directivity of the antennas in the vertical direction in order to improve the reading rate of the tag.

Japanese Unexamined Patent Publication No. 2006-20083

However, in the prior art described in Patent Document 1, since the beam scan is performed in the vertical direction, it is possible to read over a wide range in the height direction, but the beam width in the transport direction is narrow and the RF tag is in the beam. The reading rate could not be improved because the time stayed at was short.

It is conceivable to set the beam width of the transmitting / receiving antenna so as to widen along the transport direction, prolong the time that each RF tag stays in the beam of one antenna, and improve the reading rate. However, in this case, there is a problem that there is a high possibility that tags that do not need to be read existing in the surroundings are erroneously read.

It is an object of the present disclosure to provide a technique for improving the reading performance of an RF tag attached to an article moving along a transport path.

One aspect of the present disclosure is a tag reading system, which may include a position detection unit, a directional variable antenna, a tag reading unit, and a control unit. The position detection unit detects the position of the article in the work section set in the transport path for transporting the article. The directional variable antenna irradiates radio waves toward the working section. The tag reader reads information from the RF tag attached to the article via the directional variable antenna. The control unit changes the direction of the beam of the directional variable antenna along the transport path according to the position of the article detected by the position detection unit. Further, the control unit changes the transmission / reception conditions of the tag reading unit so that the closer the direction of the beam is to the entrance / exit of the working section, the lower the misreading rate by the tag reading unit.

According to such a configuration, the direction of the beam of the directional variable antenna is changed according to the position of the article in the working section, so that the time during which the RF tag attached to the article stays in the beam, that is, the RF tag The time available for reading is increased. As a result, the reading rate of the RF tag by the tag reading unit can be improved.

In addition, since the transmission / reception conditions of the tag reading unit are changed so that the tag misreading rate decreases as the beam direction is closer to the entrance / exit of the working section, it is necessary to erroneously read the information of the RF tag existing outside the working section. Can be suppressed.

In one aspect of the present disclosure, the transmission / reception condition may include at least the transmission power supplied by the tag reader to the directional variable antenna.
In this case, as the direction of the beam is closer to the entrance / exit of the work section, the transmission power can be reduced to suppress the leakage of radio waves outside the work section.

In one aspect of the present disclosure, the transmission / reception condition may include at least a parameter that changes the reception sensitivity of the tag reading unit with respect to the reception signal from the directional variable antenna. This parameter may include, for example, a reception threshold used to identify at the reception level whether the reception signal is valid or not.
In this case, it is possible to suppress reception of radio waves from RF tags located outside the working section with readable strength.

In one aspect of the present disclosure, the directional variable antenna may be located lateral to the working section.
In this case, for example, as compared with the case where the directional variable antenna is arranged above the work section, the leakage of radio waves to the outside of the work section can be suppressed more easily. For example, when a radio wave absorber is used to suppress radio wave leakage, a side wall may be provided at a position opposite to the side irradiation, and the radio wave absorber may be arranged from above. A radio wave absorber must be placed on the road surface of the transport path for the irradiation. In this case, the road surface on which the radio wave absorber is arranged becomes inconvenient due to a step or the like.

In one aspect of the present disclosure, the position detector may include two end sensors and a central sensor. The end sensors detect at both ends of the work section, which is the entrance / exit of the work section. The central sensor detects at the center of the work section. When only one of the two end sensors responds, the control unit activates the tag reader and directs the beam of the directional variable antenna toward the entrance / exit of the working section where the responding sensor is located. .. Then, when the central sensor reacts, the beam may be controlled to be directed to the center of the working section regardless of the reaction of the two end sensors.

According to such a configuration, it is possible to secure a long reading time under the transmission / reception condition where the reading rate of the RF tag by the tag reading unit is high, so that the reading rate of the RF tag in the entire working section can be improved.

In one aspect of the present disclosure, the control unit uses the tag reading unit when the detection result of the position detecting unit does not change continuously for a predetermined allowable time or more by the position detecting unit during the operation of the tag reading unit. You may stop it.

According to such a configuration, it is possible to prevent the tag reading unit from continuing to operate unnecessarily after an article normally exits the work section or when an error such as an article staying in the work section occurs. it can.

It is a block diagram which shows the whole structure of a tag reading system. It is a perspective view which shows the structure of the gate part. It is a flowchart of the reading process executed by a reader / writer. It is a flowchart of the reading process executed by a reader / writer. It is explanatory drawing which shows how the direction of the beam of a directivity variable antenna changes according to the position of an article.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. Constitution]
The tag reading system 1 of the present embodiment is provided in a transport path for transporting an article, and is for reading identification information from an RF tag attached to the transported article. The article may be transported by an operator using a trolley, or may be automatically transported by a transport device such as a belt conveyor. Here, a case where a plurality of articles to which RF tags are attached are collectively transported by using a trolley will be described.

As shown in FIG. 1, the tag reading system 1 includes a gate portion 2, a reader / writer 3, and a display device 4.
As shown in FIG. 2, the gate portion 2 includes a first side wall portion 21 and a second side wall portion 22 arranged to face each other on the left and right sides of the transport path along the transport path, and limits the area through which the article passes. .. In the transport path, the section sandwiched between the first side wall portion 21 and the second side wall portion 22 is referred to as a work section.

The first side wall portion 21 and the second side wall portion 22 are assembled so as to have a thick and flat box-shaped outer shape by using, for example, a plurality of rod-shaped pipes and a pipe connecting tool for connecting the pipes. It is constructed using a frame.

The antenna unit 5 and the sensor unit 6 are attached to the facing surface 21a of the first side wall portion 21, and the mirror unit 7 is attached to the facing surface 22a of the second side wall portion 22. The facing surfaces 21a and 22a refer to surfaces facing each other on the first side wall portion 21 and the second side wall portion 22. The antenna unit 5 corresponds to a directional variable antenna, and the sensor unit 6 and the mirror unit 7 correspond to a position detection unit.

The antenna unit 5 is arranged near the center of the first side wall portion 21 in the height direction. The sensor unit 6 is arranged near the lower end of the first side wall portion 21 at a position higher than the wheel shaft of the carriage 8. The mirror unit 7 is arranged at a position of the second side wall portion 22 facing the sensor unit 6 of the first side wall portion 21.

The facing surface 21a other than the portion to which the antenna unit 5 and the sensor unit 6 are attached in the first side wall portion 21, and the facing surface 22a other than the portion to which the mirror unit 7 is attached in the second side wall portion 22 both absorb radio waves. Covered with wood.

The antenna unit 5 has a plurality of antenna elements arranged in a row, and the direction of the emitted beam is changed by changing the feeding phase to each antenna element according to the control signal from the reader / writer 3. A variable variable antenna is used. The beam of the antenna unit 5 has a large spread in the height direction and a narrowed shape in the horizontal direction. Then, the beam is attached to the first side wall portion 21 so as to change its direction in the horizontal direction, that is, in the direction along the transport path.

The direction of the beam that can be controlled by the control signal is the front direction, the first end direction, and the second end direction. When the direction of the beam is the front direction, radio waves are radiated near the center along the transport direction in the work section. When the direction of the beam is the first end direction, the radio wave is radiated toward one of both ends which is the entrance / exit of the working section. When the direction of the beam is the second end direction, the radio wave is radiated toward the other of both ends that are the entrances and exits of the working section. In FIG. 2, the direction facing the front side of the gate portion 2 is the first end direction, and the direction facing the back side of the gate portion 2 is the second end direction.

Further, the transmission / reception conditions of the reader / writer 3 include at least one of the transmission power supplied to the antenna unit 5 and the reception threshold value used for identifying whether or not the reception signal from the antenna unit 5 is valid at the reception level. One is included, and there are two stages, a normal setting and a suppression setting. In the suppression setting, the transmission power is smaller than the normal setting and the reception threshold is larger than the normal setting, based on the transmission power and the reception threshold value in the normal setting. In addition, instead of the reception threshold value, other parameters that change the reception sensitivity may be used.

The control signal is a DC signal having a plurality of signal levels, and each signal level is associated with a combination of a beam direction and transmission / reception conditions. Here, since the first end direction and suppression setting, the second end direction and suppression setting, and the center direction and normal setting are used, the control signal has three signal levels. Further, the control signal is transmitted between the antenna unit 5 and the reader / writer 3 using the same signal line as the signal line for transmitting the high frequency signal transmitted / received. However, the high frequency signal and the control signal may be individually transmitted using different signal lines.

The beam direction, horizontal beam width (that is, half-value angle), transmission power under transmission / reception conditions, and reception threshold value are the reading rates from RF tags located outside the working section in both of the following two cases. The misreading rate is set to be less than or equal to a preset allowable value. That is, when the beam direction is the front direction and the transmission / reception condition is the normal setting, and when the beam direction is the first end direction or the second end direction and the transmission / reception condition is the suppression setting.

The sensor unit 6 has three sensors 61 to 63 arranged in a row. The sensor located at the center (hereinafter referred to as the central sensor) 62 is arranged so as to be located at the center of the working section. Two sensors (hereinafter, end sensors) 61 and 63 located on both sides of the central sensor 62 are arranged at the entrance and exit of the working section at the boundary with the outer section. Further, the mirror unit 7 includes two mirrors 71 and 73 arranged at positions facing the end sensors 61 and 63.

As the central sensor 62, a sensor that irradiates infrared rays, ultrasonic waves, visible light, or the like and detects an object by the strength of reflection is used. The end sensors 61 and 63 irradiate visible light or infrared rays (hereinafter referred to as light rays) and detect an object depending on whether or not the reflected light from the mirrors 71 and 73 of the mirror unit 7 arranged in the front is received. A mirror reflective sensor is used.

That is, the end sensors 61 and 63 accurately detect articles existing at positions that block the reciprocating path of the light beam, that is, articles that have entered the work section or articles that have left the work section. The central sensor 62 detects an object existing in a wider range centered in the front direction. However, the detection range of the central sensor 62 is set so as not to include the detection range of the end sensors 61 and 63.

The display device 4 is for displaying a processing result or the like by the reader / writer 3, and a liquid crystal display or the like is used.
The reader / writer 3 is composed of a microcomputer including a CPU, a ROM, a RAM, and the like. Further, the reader / writer 3 is provided with a plurality of IO ports, and is used for controlling the antenna unit 5, the sensor unit 6 and the display device 4, communicating with an external device, and the like.

The reader / writer 3 executes at least the tag reading process and the main process. The tag reading process is an original process of the reader / writer that extracts RF tag information from the received signal of the antenna unit 5, and is an existing process. Therefore, the description thereof is omitted here. The main process performs control of the antenna unit 5 and control of starting and stopping the tag reading process according to the detection signal from the sensor unit 6. The tag reading process corresponds to the tag reading unit, and the main process corresponds to the control unit.

The RAM of the reader / writer 3 is provided with at least an area for storing a passage history indicating how each of the sensors 61 to 63 belonging to the sensor unit 6 reacts as the article group passes through the working section. This passage history is deleted every time the passage of the work section by one group of goods is completed.

[2. processing]
The main process executed by the reader / writer 3 will be described with reference to the flowcharts of FIGS. 3 and 4.

The main process starts the process when any of the sensors 61 to 63 reacts in the sensor unit 6. However, when the reader / writer 3 is activated, the antenna unit 5 is initialized to an off state in which transmission / reception is not executed, and the tag reading process is initialized to a stopped state.

When the main process is started, in S110, the reader / writer 3 determines whether or not the sensor that has reacted in the sensor unit 6 is one of the end sensors 61 and 63. If a positive determination is made in S110, the process is transferred to S120, and if a negative determination is made, the process is transferred to S160. In the following, among the end sensors 61 and 63, the end sensor determined to have reacted in this step is referred to as an inlet sensor, and the other end sensor is referred to as an exit sensor.

In S120, the reader / writer 3 determines whether or not the passage history has been recorded, and if a positive determination is made, the process shifts to S150, and if a negative determination is made, the process shifts to S130. That is, the affirmative judgment in S120 means that another article group has already entered the work section, and the negative determination in S120 means that a new article group has entered the work section.

In S130, the reader / writer 3 directs the directivity of the antenna toward the inlet sensor, sets the transmission / reception condition to suppress, and starts reading the RF tag by invoking the tag reading process.

In the following S140, the reader / writer 3 stores the entrance sensor as the passage history and proceeds to the process in S160.
In S150, the reader / writer 3 confirms the passage history, executes an error determination, and advances the process to S310. In this error determination, it is determined whether or not the article group to which the entrance sensor has reacted is an unauthorized entry. Specifically, if the passage history already stores the end sensor and the center sensor that are different from the end sensor that responded this time, it is not an error because it is detected by the movement of the sensor currently being read. Is determined. If only the end sensor that has reacted this time is already stored in the passage history, it is determined that the error is due to an unauthorized entry of a new group of articles even though the reading is currently in progress. If only the end sensor different from the end sensor that responded this time is already stored in the passage history, an error caused by the reading article group passing through the central sensor 62 for some reason, or a failure of the central sensor 62. It is determined that the error is due to.

In S160, the reader / writer 3 determines whether or not the central sensor 62 has reacted in the sensor unit 6, and if a positive determination is made, the process shifts to S180, and if a negative determination is made, the process is changed to S170. Transition. If an affirmative judgment is made in S110, the affirmative judgment is made if the article group has reached the detection area of the central sensor 62, and a negative judgment is made if the article group has not reached the detection area, depending on the movement status of the article group in the work section. To.

In S170, the reader / writer 3 determines whether or not a preset allowable time has elapsed since the inlet sensor responded, and if a positive determination is made, the process shifts to S190, and if a negative determination is made, the process is processed. Is returned to S160.

In S180, the reader / writer 3 determines whether or not there is a passage history of the entrance sensor, and if a positive determination is made, the process shifts to S200, and if a negative determination is made, the process shifts to S190. That is, the affirmative judgment in S180 means that the article group has moved from the entrance sensor to the detection range of the central sensor 62, and the negative judgment in S180 suddenly does not cause the end sensors 61 and 63 to react. It means that the central sensor 62 has reacted.

In S190, the reader / writer 3 executes an error determination by checking the passage history, and advances the process to S310. Specifically, in the error determination, the following determination is performed. When the process proceeds to this step by making an affirmative judgment in S170, only the entrance sensor is recorded in the passage history. In this case, it is determined that the group of articles that have entered the work section is staying in front of the detection range of the central sensor 62, or that the central sensor 62 is out of order. Further, when the process proceeds to this step due to a negative determination in S180, the article group has slipped through the end sensors 61 and 63 for some reason, or the end sensors 61 and 63 have failed. Is determined.

In S200, the reader / writer 3 switches the directivity of the antenna toward the center and switches the transmission / reception conditions to the normal settings while continuing to read the RF tag by the tag reading process.

In the following S210, the reader / writer 3 adds the central sensor 62 to the passage history.
In the following S220, the reader / writer 3 determines whether or not the exit sensor has reacted in the sensor unit 6, and if a positive determination is made, the process shifts to S250, and if a negative determination is made, the process is changed to S230. Transition.

In S230, the reader / writer 3 determines whether or not a preset allowable time has elapsed since the central sensor 62 responded, and if a positive determination is made, the process shifts to S240, and if a negative determination is made, the process shifts to S240. The process is returned to S220. The permissible time used in this step may be the same length as the permissible time used in the previous S170, or may be a different length.

In S240, the reader / writer 3 executes an error determination by checking the passage history, and advances the process to S310. Specifically, in the error determination, the following determination is performed. That is, in this case, since the entrance sensor and the central sensor 62 are recorded in the passage history, the group of articles that have entered the work section stays within the detection range of the central sensor 62 or in front of the detection range of the exit sensor. Alternatively, it is determined that the exit sensor is out of order.

In S250, the reader / writer 3 determines whether or not the central sensor 62 is responding, and if a positive determination is made, the reader / writer 3 waits by repeating this step, and if a negative determination is made, the process shifts to S260. The affirmative judgment in S250 is that the central sensor 62 is also responding even though the exit sensor is responding, and a long article group is passing through the work section along the transport path. Means. Further, the negative determination in S250 means that the article group that has entered the work section has reached the detection range of the exit sensor without detecting an abnormality.

In S260, the reader / writer 3 switches the directivity of the antenna toward the exit sensor and switches the transmission / reception condition to the suppression setting while continuing to read the RF tag by the tag reading process.

In the following S270, the reader / writer 3 adds an exit sensor to the passage history.
In the following S280, the reader / writer 3 detects the passing direction of the article group from the contents of the passing history.

In the following S290, the reader / writer 3 determines whether or not the exit sensor is responding, and if a positive determination is made, the reader / writer 3 waits by repeating this step, and if a negative determination is made, the process shifts to S300. The positive judgment in S290 means that a part of the article group remains in the work section, that is, the passage of the work section by the article group is incomplete, and the negative judgment in S290 is the article. It means that the passage of the work section by the group has been completed.

In S300, the reader / writer 3 turns off the transmission / reception by the antenna unit 5 and stops the tag reading process to end the reading of the RF tag. Further, the reader / writer 3 displays the reading result of the RF tag and proceeds to the process in S320. The reading result in the tag reading process includes the number of tags read and the passing direction of the article group. The passing direction can be used, for example, as information for identifying whether the product is shipped or received.

In S310, the reader / writer 3 terminates the reading of the RF tag by turning off the transmission / reception by the antenna unit 5 and stopping the tag reading process, assuming that some error has been detected. Further, the reader / writer 3 displays the type of the detected error on the display device 4, and proceeds to the process in S320.

In S320, the reader / writer 3 outputs the processing result to the external device.
In the following S330, the reader / writer 3 deletes the passage history and ends the process.
[3. motion]
In the tag reading system 1, as shown in FIG. 5A, when the carriage 8 carrying the article group to which the RF tag is attached enters the gate portion 2 (that is, the working section) from the end sensor 61 side, The end sensor 61 reacts. In this case, the end sensor 61 is the inlet sensor and the end sensor 63 is the exit sensor. Then, the direction of the beam B of the antenna unit 5 is set to face the entrance / exit of the work section where the end sensor 61 is arranged, the transmission / reception conditions are set to the suppression setting, and the reader / writer 3 reads the RF tag. Is started.

When the dolly 8 advances through the work section and reaches the detection range of the central sensor 62, the direction of the beam B is in the front direction while the reading of the RF tag by the reader / writer 3 is continued as shown in FIG. 5 (b). The transmission / reception conditions are switched to the normal settings.

Even if the dolly 8 advances further in the work section and reaches the position where the end sensor 63, which is the exit sensor, reacts, the direction of the beam B and the transmission / reception conditions are determined while the central sensor 62 is reacting. The settings are retained.

When the dolly 8 further advances in the work section and reaches a position outside the detection range of the central sensor 62, the direction of the beam B while the reading of the RF tag by the reader / writer 3 is continued as shown in FIG. 5 (c). However, the transmission / reception condition is switched to the suppression setting while the end sensor 63 is switched in the direction facing the entrance / exit of the working section where the end sensor 63 is arranged.

After that, when the carriage 8 exits the work section and reaches a position outside the detection range of the end sensor 63, the transmission / reception by the antenna unit 5 is turned off, and the reading of the RF tag by the reader / writer 3 is also stopped.

[4. effect]
In the present embodiment described above, the following effects are obtained.
(A) The tag reading system 1 detects the positions of the carriage 8 and the articles mounted on the carriage 8 in the work section, and follows the direction of the beam according to the detection result that changes according to the movement of the carriage 8. Therefore, the time that the RF tag attached to each article belonging to the article group stays in the beam of the antenna unit 5, that is, the time that can be used for reading the RF tag becomes long, so that the reading rate of the RF tag by the reader / writer 3 becomes long. Can be improved.

(B) In the tag reading system 1, when the direction of the beam is toward the entrance / exit of the work section, the transmission / reception condition is set to be suppressed to reduce the misreading rate of the RF tag by the reader / writer 3. Therefore, it is possible to prevent erroneous reading of RF tag information existing outside the working section.

(C) In the tag reading system 1, since the detection results of the sensors 61 to 63 belonging to the sensor unit 6 are stored as the passage history, not only the passage direction of the article group in the work section can be detected from the passage history, but also an error. When it occurs, the type of error can be determined.

[5. Other embodiments]
Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various aspects can be taken without departing from the gist of the present disclosure.

(A) In the above embodiment, the sensor unit 6 detects the position of the article group using the three sensors 61 to 63, and the antenna unit 5 controls the beam direction in three directions according to the detection result. However, it is not limited to these. The sensor unit 6 may have two or four or more sensors. Further, the direction of the beam controlled by the antenna unit 5 may be two directions or four or more directions.

(B) In the above embodiment, the sensor unit 6 and the mirror unit 7 are arranged near the lower ends of the first side wall portion 21 and the second side wall portion 22, but the present invention is not limited to this, and the article passes through. Any position may be used as long as the position of the group can be detected. Further, the first side wall portion 21 and the second side wall portion 22 may have a structure capable of arbitrarily changing the positions and orientations of the sensor unit 6 and the mirror unit 7. Further, depending on the type of sensor used, the sensor unit 6 may be arranged on a top wall portion that covers the upper part of the first side wall portion 21 and the second side wall portion 22, or a floor surface portion that covers the lower portion.

(C) In the above embodiment, the sensor unit 6 uses different sensors for the end sensors 61 and 63 and the central sensor 62, but all of them may use the same type of sensor. Further, the type of sensor used is not particularly limited.

(D) In the above embodiment, the end sensors 61 and 63 are arranged so as to detect a group of articles entering the working section and a group of articles leaving the working section. For example, immediately before entering the working section. , And may be arranged to detect a group of articles immediately after leaving the work section.

(E) In the above embodiment, after the exit sensor reacts, the reading of the RF tag ends when the reaction disappears. For example, after the exit sensor reacts, a predetermined time elapses from the RF tag. The reading may be finished.

(F) In the above embodiment, the antenna unit 5 is arranged so as to irradiate the beam from the side of the transport path, but the top wall portion is provided at the upper ends of the first side wall portion 21 and the second side wall portion 22. It may be arranged so as to irradiate downward from the top wall portion. In this case, the floor surface may be covered with a radio wave absorber in order to suppress reflection from the floor surface of the transport path. Further, the first side wall portion 21 and the second side wall portion 22 may have a structure capable of arbitrarily changing the position and orientation of the antenna unit 5. In this case, the antenna unit 5 may be arranged so as to irradiate diagonally downward from the vicinity of the upper end of the first side wall portion 21, for example.

(G) In the above embodiment, only one antenna unit 5 is provided in the gate portion 2, but a plurality of antenna units 5 may be provided at positions having different heights. In this case, the reader / writer 3 may process the signals from the plurality of antenna units 5 individually in a time division manner.

(H) When a plurality of articles to which RF tags are attached are stored in one storage box and a tag or barcode is also attached to the storage box, the storage box is placed outside the doorway of the gate portion 2. A reader may be provided to read information from the attached tag or barcode. In this case, it is possible to realize a control or the like that prevents another storage box from entering the gate portion 2 until one storage box passes through the gate portion 2.

1 ... Tag reading system, 2 ... Gate part, 3 ... Reader / writer, 4 ... Display device, 5 ... Antenna unit, 6 ... Sensor unit, 7 ... Mirror unit, 8 ... Cart, 21 ... First side wall, 22 ... 2 side wall portions, 21a, 22a ... facing surfaces, 61, 63 ... end sensors, 62 ... central sensors, 71, 73 ... mirrors.

Claims (6)

A position detection unit configured to detect the position of the article in the work section set in the transport path for transporting the article, and
A directional variable antenna configured to irradiate radio waves toward the work section,
A tag reader configured to read information from an RF tag attached to the article via the directional variable antenna.
The direction of the beam of the directional variable antenna is changed along the transport path according to the position of the article detected by the position detection unit, and the closer the direction of the beam is to the entrance / exit of the working section. A control unit configured to change the transmission / reception conditions of the tag reading unit so that the misreading rate by the tag reading unit is reduced.
Tag reading system. The tag reading system according to claim 1.
As the transmission / reception condition, at least the transmission power supplied by the tag reader to the directional variable antenna is included.
Tag reading system. The tag reading system according to claim 1 or 2.
The transmission / reception condition includes at least a parameter that changes the reception sensitivity of the tag reader with respect to the reception signal from the directional variable antenna.
Tag reading system. The tag reading system according to any one of claims 1 to 3.
The directional variable antenna was arranged on the side of the working section.
Tag reading system. The tag reading system according to any one of claims 1 to 4.
The position detection unit includes two end sensors that perform detection at both ends of the work section, which are entrances and exits of the work section, and a central sensor that detects at the center of the work section.
When only one of the two end sensors reacts, the control unit operates the tag reading unit and has the directivity in the direction of the entrance / exit of the working section where the responding sensor is located. A tag reading system that directs the beam of a variable antenna and controls so that when the central sensor reacts, the beam is directed to the center of the working section regardless of the reaction of the two end sensors. The tag reading system according to any one of claims 1 to 5.
During the operation of the tag reading unit, the control unit stops the tag reading unit when there is no change in the detection result of the position detecting unit continuously for a predetermined allowable time or longer by the position detecting unit. Tag reading system.

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