JP2009075728A - Radio tag reading device and its reading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the end batch management system of an article for preventing the reading mistake of a radio tag from being generated in the case of performing bi-directional communication from an interrogator by attaching a radio tag to each of individual articles. <P>SOLUTION: The weight of an article 12 to which a radio tag 13 is attached is measured in a batch, and the quantity of a radio tag 13 as the object of bi-direction communication is calculated from the measured value, and compared with the total number of radio tags 13 which have returned a response signal to an interrogator 16, and whether or not there exists the radio tag 13 whose reading mistake has been generated is judged. When there exists any reading mistake, a transmission output from the interrogator 16 is increased by one level, and this is repeated until the reading mistake is canceled. On the other hand, when the satisfactory reading of all the radio tags 13 is continued by the fixed number of times, it is considered that the bidirectional communication with the radio tag 13 is sufficiently stabilized in that environment, and the transmission output from the questioning unit 16 is decreased by one level. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an article management system using a wireless tag, and more particularly, to a wireless tag reading apparatus and a reading method thereof when each wireless tag attached to an article and an interrogator perform two-way communication.

  The wireless tag is also referred to as RFID (Radio Frequency Identification), is attached to an article, and is used for managing the attached article by performing non-contact bidirectional communication with a reader / writer device. The wireless tag holds information that can identify an individual, and can transmit the information as a response signal in response to an inquiry signal from the reader / writer device. Depending on the wireless tag, the wireless tag is transmitted from the reader / writer device. Information can also be stored in its own memory.

  The use of such a wireless tag is useful for management of individual articles in various fields such as transportation of goods and packages and process management in a factory. In particular, when RFID tags are attached to individual items such as products and packages that are subject to management, RFID tag readers are provided at each important point in the process, and the RFID tag reading results there Can be used to automate the sorting of articles.

  As a problem when attaching and managing a wireless tag to each article, there is a countermeasure when the reader / writer device cannot read the wireless tag. Generally, a wireless tag is configured as a non-powered element that does not have a power source such as a battery, uses an electromagnetic wave of an inquiry signal transmitted from a reader / writer device as operating power, and information such as a unique identification number is a reader / writer device. In many cases, a response signal is transmitted as a response signal. At this time, if an electromagnetic wave having a necessary intensity is not supplied from the reader / writer device to each wireless tag attached to the article, the wireless tag cannot operate and a response signal cannot be transmitted. In recent years, the development of a non-powered wireless tag using the UHF band has been promoted. In this case, a bidirectional communication distance of several meters to several tens of meters can be obtained.

  When sorting items with a wireless tag attached, a pallet or a carry case is used, and the wireless tag is read by the reader / writer device while a plurality of items are placed on the pallet or inside the carry case. There are many cases. If the article to which the wireless tag is attached at this time has, for example, moisture or a metal member, the moisture or the metal member absorbs and reflects electromagnetic waves from the reader / writer device, and the wireless tag in the vicinity There is a possibility that it may be an obstruction factor for electromagnetic wave reception. Further, since the article is placed in various directions, depending on the orientation of the antenna of the wireless tag attached to the article, the reception sensitivity of the wireless tag may be reduced, and sufficient operating power may not be obtained. As a countermeasure, there is a method to increase the transmission output of the inquiry signal from the reader / writer device, but there are cases where it is subject to regulation by the Radio Law, and communication is established with wireless tags other than those to be read that are located at a remote location There is a risk of it.

  As a method for solving this problem, a communication device described in Patent Document 1 has been proposed. This communication device is based on the premise that when an article is transported by a forklift or a belt conveyor, the wireless tag attached to a pallet or a carry case is read instead of an individual article to manage the article. Among these, the example in the case of conveying a carry case by a belt conveyor is demonstrated based on FIG.

  FIG. 3 is a schematic diagram showing an example of a conventional article management system using wireless tags. In FIG. 3, the conveyance path for conveying the article 32 is composed of a plurality of belt conveyors, and FIG. 3 shows a case where three belt conveyors 35a, 35b, and 35c are used as the conveyance paths. These belt conveyors convey the carry case 31 loaded with the article 32 in order from the right side to the left side in the drawing in the direction of the arrow shown in FIG. Here, the weighing device 34 is provided in the central belt conveyor 35b, and when the carry case 31 is conveyed on the belt conveyor 35b, the total weight of the articles 32 including the carry case 31 is measured. . An interrogator 36 having an antenna is provided above the belt conveyor 35b, and performs two-way communication with the wireless tag 33 attached to the carry case 31. The result is collected and processed by the processing device 37 together with the weight data of the carry case 31 and the article 32 measured by the weighing device 34.

  The processing device 37 determines whether or not the article 32 is mounted in the carry case 31 based on the weight data from the weighing device 34. Since the weight of the carry case 31 is known, the presence / absence of the article 32 can be determined based on whether or not the value obtained by subtracting the weight of the carry case 31 from the weight data in the weighing device 34 is zero. When the article 32 is present in the carry case 31, the inquiry signal transmitted from the interrogator 36 may be hindered by the presence of the article 32. Therefore, the signal output of the inquiry signal is strengthened within a certain range. ing.

  By the way, in the conventional article management system using wireless tags described in Patent Document 1, since the wireless tag is attached to the carry case instead of the individual articles, the individual articles mounted in the carry case are wireless tags. There was a problem that it was not possible to manage directly using. In recent years, in the transportation of goods and process management in factories, it is possible to trace the distribution route by explicitly managing the route until the product reaches the final recipient (consumer) hand There is a need for traceability. The same applies to the transportation of general parcels, and there is an increasing demand for recording the transportation route and making it possible to track the route of each parcel. In this case, it is considered that attaching a wireless tag to an individual item such as a product or a baggage and performing individual management using the tag is an effective means for improving traceability.

  If this management method is applied when an article is mounted in the carry case and conveyed by a belt conveyor, the method of managing the carry case with the wireless tag described in Patent Document 1 is inappropriate. Instead, a wireless tag is attached to each item mounted inside the carry case, and two-way communication is performed with each item's wireless tag using an interrogator equipped with an antenna. It is necessary to manage it. In this case, the interrogator installed at the top of the belt conveyor performs one-to-one communication with a large number of wireless tags attached to each article, so anti-collision processing, time division multiplexing, etc. Using this method, two-way communication with each wireless tag is performed.

  When the interrogator performs two-way communication with multiple wireless tags, the wireless tag that fails to establish communication on the interrogator side and fails to read cannot be recognized by the interrogator. Therefore, the article to which the wireless tag is attached becomes missing at that time. However, as in the case of the prior art described in Patent Document 1, the presence of the article itself may obstruct the bidirectional communication, and there is a problem of how to prevent this reading error.

  In general, if the signal output of the inquiry signal transmitted from the interrogator to the wireless tag is increased, this reading error is considered to decrease, but it is not possible to confirm how much this signal output is increased to eliminate the reading error. Conventionally, the system administrator has counted the number of articles visually and compared it with the number of wireless tags established for two-way communication. However, this method places a heavy burden on the system administrator and has a problem of counting errors. In addition, if the signal output of the interrogation signal from the interrogator is always extremely large, it may be possible to establish two-way communication with all the wireless tags, but in this case, the regulation by the Radio Law becomes a problem, There is a possibility that the interrogator may perform two-way communication with the wireless tag of the article other than the surrounding reading target. To prevent this, measures such as providing a large space for installing the article or providing an electromagnetic barrier at a key point Will be necessary. All of these measures are not preferable because they are likely to increase the management cost of goods.

  Patent Document 2 is an example of a conventional method for solving these problems. Unlike the case of Patent Document 1, one wireless tag is attached to each article, not a carry case. These articles are placed in a case made of a material that does not hinder two-way communication with the wireless tag, or placed on the weight measuring means without a case, and the total weight is measured. On the other hand, the interrogator performs two-way communication with the wireless tag of each article and reads the ID information of each article. Next, the interrogator accesses the database to which the interrogator is connected, inquires about the read ID information, obtains the weight information of each article corresponding to these IDs from this database, and obtains the sum. Next, the total weight measured by the weight measuring means is compared with this sum to determine whether or not there is a wireless tag having a response error.

  Further, Patent Document 3 is a method similar to Patent Document 2, but the weight information of each article is not stored in the database to which the interrogator is connected, but individual wireless devices attached to the article. The tag itself holds data as data. When the interrogator performs two-way communication with the wireless tag of each article, the weight information of each article is read together with the ID information of each article, and the sum is obtained.

JP 2006-347713 A JP 2005-196384 A JP 2001-289705 A

  As described above, the methods described in Patent Documents 2 and 3 all solve the problems of the conventional method described in Patent Document 1, but these conventional methods have new problems. It was. The methods described in Patent Documents 2 and 3 are based on the premise that the weights of individual articles that perform communication at the same time are different. This is a necessary condition when paying for goods at the cash register in the store, but on the other hand, in the case of process management at the factory and product shipment management, many items of the same shape and weight are required. Often managed. Even in such a case, with the methods described in Patent Documents 2 and 3, the same weight value is read from the database and each wireless tag over the same number of times as the number of wireless tags. Therefore, there has been a problem that a series of processing time required for bidirectional communication between the interrogator and the wireless tag becomes longer due to repetition of data processing of the same value. Furthermore, the same value as the weight data of each article needs to be stored in advance in a database or a wireless tag, but this storage work also requires a considerable amount of man-hours.

  In addition, what kind of measures should be taken when there is a difference between the total weight of articles calculated from the information on the weight of individual articles and the total weight actually measured by the weight measuring means? There is no specific description in Documents 2 and 3. In both Patent Documents 2 and 3, there is a description that if the total weights of both do not match, the notification means notifies the administrator and prompts the article to be read again. Even if it is carried out again under the same conditions, there is a high possibility that a reading error will occur again, and this alone will not solve the occurrence of the reading error of the wireless tag. Therefore, in bidirectional communication with a wireless tag after the occurrence of a reading error, it is necessary to read the wireless tag again after changing some communication condition, and it is necessary to propose a procedure for changing the communication condition.

  Accordingly, a problem to be solved by the present invention is that when a wireless tag is attached to an article having substantially the same weight and managed collectively, the wireless tag reading device does not need to store the individual weight for each article in advance. , And a method for reading a wireless tag based on the above. This proposal also includes a proposal for a specific procedure for increasing or decreasing the setting value of the inquiry signal output by the interrogator according to the method for determining the signal output of the inquiry signal.

  In order to solve the above problem, in the present invention, first, the number of wireless tags attached to each article to be managed once is calculated. This quantity is, for example, the total number of wireless tags attached to each article mounted on one movable carrier, and this number matches the number of articles to be managed. If the weight of each article is substantially the same, the total weight of the article to which the wireless tag is attached is measured, and the quantity of this article is obtained by dividing by the weight per piece. Can do.

  In general, in the process management at the factory and the shipment of the product, a large number of the same type products are often conveyed continuously. In such a case, the weights of the plurality of articles to be managed are often substantially the same. . At this time, the quantity of articles included in one management target can be obtained by the above method. This method is obtained from the total weight when articles of various weights are mixed, or the articles attached with the wireless tag are light, and a large number of articles are included in one management target. It cannot be applied when there is an error in the number of articles. However, this problem can be solved to some extent by a method such as putting together the same kind of goods as much as possible and making it a management target for one time or setting an upper limit on the number of goods to be managed once. Can be solved. By the above method, the quantity of articles included in one management target is obtained at the time of article conveyance, and this value is set as the real number of wireless tags that can respond to the inquiry signal.

  Next, the interrogator transmits an inquiry signal to each individual wireless tag, actually reads the wireless tag, and counts the number of wireless tags for which two-way communication has been established. The result is compared with the real number of the wireless tag obtained from the total weight of the article, and it is determined whether or not there is a wireless tag having a reading error. If there is a radio tag that has been misread, increase the signal output of the interrogation signal from the interrogator, read the individual radio tag again, and again the real number of radio tags included in one management target Compare with Further, this operation is repeated until there is no wireless tag that causes a reading error or the signal output of the inquiry signal from the interrogator reaches the upper limit. Note that the upper limit value of the signal output is determined in consideration of the regulation by the Radio Law and the conditions for establishing two-way communication with a wireless tag of an article other than the management target.

  On the other hand, it may be confirmed from the reading result of the wireless tag that there is no wireless tag that has failed to be read, and even if the wireless tag to be communicated is replaced, this state may continue for a certain number of times. is there. In this case, it is determined that the current signal output of the inquiry signal is sufficiently large, and the wireless tag is read by reducing the signal output of the inquiry signal from the next time onward. This operation may be repeated, and can be continued until the lower limit of the signal output is reached when the bidirectional communication condition with the wireless tag is stable in a good state.

  In addition, when the signal output of the inquiry signal from the interrogator is considerably large, the number of wireless tags for which bidirectional communication is established by transmission of inquiry signals is more than the actual number of wireless tags obtained from the total weight of the articles. It is also possible to increase the number. In this case, it is considered that a wireless tag not included in the management target returns a response signal to the interrogator and is established as a two-way communication that is not attached to an article in a single management target. . In such a case, the signal output of the inquiry signal from the interrogator will be too large. Decrease the signal output of the inquiry signal and read the individual RFID tag again until this number matches. The output is repeatedly reduced.

  In the solution of the present invention, the reading error of the wireless tag and the reply of the response signal from the wireless tag other than the management target are eliminated only by increasing / decreasing the signal output of the inquiry signal. Therefore, when both the reading error and the reply from other than the management target exist at the same time, the state cannot be solved. Further, when both of them exist at the same time, it cannot be known from the total number of articles or the number of wireless tags based on response signals, and the situation cannot be recognized. Therefore, the manager of the articles to be transported should set the interval and arrangement between the containers carrying the articles to be managed once so that the response from the wireless tag other than the management target does not reach the interrogator. It is important to give due consideration to operations.

  That is, the present invention is a measuring means for measuring the total weight of the article attached with the wireless tag, which is present in the specific area, and a means for calculating the total number of the articles from the measured value of the total weight by the measuring means; Two-way communication is established from means for transmitting an inquiry signal from the interrogator to each article, receiving a response signal from the wireless tag attached to each article, and the response signal received by the interrogator Based on the calculation means for calculating the total number of wireless tags, the total number of articles calculated from the measured value of the total weight, and the total number of wireless tags established by the two-way communication calculated from the response signal A wireless tag reader comprising: setting means for setting the output of the interrogator; and output adjustment means for changing the output of the interrogator according to a set value of the output by the setting means.

  Further, the present invention compares the total number of articles calculated from the measured value of the total weight with the total number of wireless tags established by the two-way communication calculated from the response signal, from the response signal The total number of wireless tags established by the two-way communication is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is less than a preset maximum value. The output value of the interrogator is reset to a higher value than before, and the output adjustment means changes the output of the interrogator according to the reset output value. A wireless tag reader.

  Further, the present invention compares the total number of articles calculated from the measured value of the total weight with the total number of wireless tags established by the two-way communication calculated from the response signal, The calculated total number of wireless tags with which the two-way communication has been established matches the total number of articles calculated from the measured value of the total weight, and the match is continuously performed over a plurality of preset times. And when the output of the interrogator exceeds a preset minimum value, the set value of the output of the interrogator is reset to a lower value than before, and the reset output The wireless tag reader is characterized in that the output adjusting means changes the output of the interrogator according to the set value.

  Further, the present invention compares the total number of articles calculated from the measured value of the total weight with the total number of wireless tags established by the two-way communication calculated from the response signal, The calculated total number of wireless tags established by the two-way communication exceeds the total number of articles calculated from the measured value of the total weight, and the output of the interrogator exceeds a preset minimum value. The output value of the interrogator is reset to a lower value than before, and the output adjustment means changes the output of the interrogator according to the reset output value. A wireless tag reader.

  Furthermore, the present invention is a case where the respective weights of the articles substantially coincide with each other, and the RFID tag reader stores in advance the weight of each article, and the total number of the articles The wireless tag reader is characterized in that the means for calculating the total number of the articles is calculated by dividing the total weight of the articles measured by the measuring means by the weight per one of the articles. It is.

  Further, according to the present invention, the articles are collectively mounted on a movable carrier, and measuring means for measuring the total weight of the article is installed on a lower surface of a moving path through which the movable carrier passes. The wireless tag reader is characterized.

  Further, according to the present invention, an antenna that forms the interrogator and performs two-way communication with each wireless tag attached to the article is installed above a moving path through which the movable carrier passes. The wireless tag reader is characterized.

  Further, the present invention provides the interrogator by measuring the total weight of the articles attached to the wireless tag existing in the specific area by the measuring means, calculating the total number of the articles from the measured value of the total weight by the measuring means. A wireless tag in which two-way communication is established from the response signal received by the interrogator, which transmits an inquiry signal to each of the articles, receives a response signal from the respective wireless tag attached to each article The total number of articles calculated from the measured value of the total weight is compared with the total number of wireless tags established by the two-way communication calculated from the response signal, and calculated from the response signal. The total number of wireless tags established by the two-way communication is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is less than a preset maximum value. In this case, the set value of the output of the interrogator is reset to a higher value than before, and the total number of wireless tags established by the two-way communication calculated from the response signal is calculated from the measured value of the total weight. The total number of articles received, the match is obtained continuously for a plurality of preset times, and the output of the interrogator exceeds a preset minimum value The set value of the output of the interrogator is reset to a lower value than before, and the total number of wireless tags established by the two-way communication calculated from the response signal is calculated from the measured value of the total weight When the total number of articles is exceeded and the output of the interrogator exceeds a preset minimum value, the setting value of the output of the interrogator is reset to a lower value than before. This is a method of reading a wireless tag.

  Furthermore, the present invention is a case where the weight of each of the articles is substantially equal to each other, the weight per one of the articles is measured in advance, and the means for calculating the total number of the articles is The wireless tag reading method is characterized in that the total number of the articles is calculated by dividing the total weight of the articles measured by the measuring means by the weight per one of the articles.

  Furthermore, the present invention provides that the total number of wireless tags established by the two-way communication calculated from the response signal is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator Is less than the preset maximum value, and when the set value of the output of the interrogator is reset to a higher value than before, the output adjustment means according to the set value of the output that has been reset The output of the interrogator is changed, and the total number of wireless tags established by the two-way communication calculated from the response signal exceeds the total number of the articles calculated from the measurement value of the total weight, and the question If the output of the instrument exceeds the preset minimum value and the set value of the interrogator is reset to a lower value than before, the output is made according to the reset set value of the output. The adjustment means is the interrogator. When the output is changed and the output of the interrogator is changed, the interrogator immediately transmits an inquiry signal to each article according to the changed output, and a response signal from each wireless tag attached to each article Is received again, and the total number of wireless tags for which two-way communication has been established is calculated again from the response signal received by the interrogator.

  According to the present invention, in the collective management of articles each attached with a wireless tag, the total number of articles calculated from the total weight of articles to be managed and the number of wireless tags that responded to the inquiry signal are compared. It is determined whether or not there is a radio tag that has caused a reading error, and thereby the signal output of the inquiry signal from the interrogator is increased or decreased. By performing this article collective management method, it is possible to individually manage articles using wireless tags, and one-to-one two-way communication can be performed between the interrogator and each wireless tag. it can. In addition, the total number of wireless tags included in one management target is managed, and the signal output of the inquiry signal is constantly increased or decreased. By this method, it is possible to prevent as much as possible the reading error of the wireless tag and the reply from the wireless tag other than the management target as much as possible, and it is possible to prevent the occurrence of articles that are missing due to omission of management as much as possible.

  Hereinafter, a wireless tag reader according to an embodiment of the present invention and a reading method using the same will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic diagram showing an example of an article management system according to an embodiment of the present invention. In this management system, the total weight of each article is measured for each movable carrier while conveying a plurality of articles mounted on the movable carrier. At the same time, two-way communication is performed with the wireless tag attached to each article, and the transmission output at that time is set using the measured value of the total weight of each article. In FIG. 1, a plurality of articles 12 mounted on the movable carrier 11 are each attached with a single wireless tag 13, and are conveyed while mounted on the movable carrier 11. This movable carrier 11 has a self-propelled function and can move on the floor 15. A function of measuring the total weight of the article 12 including the movable carrier 11 when a weight sensor 14 is installed on a part of the floor surface 15 and it is detected that the movable carrier 11 is passing over it. The measurement result is transmitted to the processing device 17 as weight data of the movable carrier 11 and the mounted article 12.

  On the other hand, an interrogator 16 equipped with an antenna is provided above the weight sensor 14, and performs bidirectional communication with the wireless tag 13 attached to each article 12 in the movable carrier 11. The response signal from the wireless tag 13 is collected and processed in the processing device 17 as a communication result, similarly to the weight measurement result. The processing device 17 first subtracts the weight of the movable carrier 11 from the weight data transmitted from the weight sensor 14, and then divides the weight by the weight per one of the articles 12 to determine the article 12 mounted on the movable carrier 11. Calculate the quantity. The values of the weight of the movable carrier 11 and the average weight of the article 12 are given to the processing device 17 in advance. Next, the interrogator 16 analyzes the result of the response signal received from each wireless tag 13 and counts the number of wireless tags 13 that have responded. Then, the quantity of the article 12 obtained from the weight data is compared with the quantity of the response number of the wireless tag 13, and the transmission output in the bidirectional communication from the interrogator 16 is increased or decreased based on the result.

  FIG. 2 shows a flowchart of an example of a procedure for increasing or decreasing the transmission output transmitted from the interrogator to the wireless tag. A series of procedures shown in FIG. 2 is executed by the processing device. Here, the intensity of the transmission output E that can be set by the interrogator is assumed to be E1, E2,..., Ej (where E1 <E2 <... <Ej). Here, j is a positive integer. For example, when the transmission output of the interrogator can be changed in five stages, j = 5. In addition, the transmission output E of the interrogator in the initial state is Ek (where k is a positive integer, 1 ≦ k ≦ j). In addition, if there is no reading error by the interrogator and the state of smooth two-way communication continues for a certain number of times, it is determined that the two-way communication condition is stable, and the following sequence of steps from the interrogator Decrease the intensity of the transmitted output by one step. A value serving as a criterion for determining the number of consecutive bidirectional communications for making this determination is defined as N (times) (where N is a positive integer, 2 ≦ N). N (times) is a determination value of the number of repetitions given in advance as a set value. Note that the weight per article is b. This value is given in advance to the processing apparatus.

  In FIG. 2, when the procedure for increasing / decreasing the transmission output from the interrogator is started (S1), the determination value N of the number of repetitions, the transmission output E of the interrogator, the parameter a (0 ≦ a ≦ N) are first performed. ) And a parameter k are defined (S2). Here, the parameter a is the number of repetitions in a state where no reading error occurs by the interrogator, and initially a = 0. K is a parameter that defines the value of the current transmission output E of the interrogator, and is determined based on the results of bidirectional communication between the series of interrogators and each wireless tag up to the previous time (S3). When the output value Ek is set as the value of the transmission output E from the interrogator (S4), the interrogator enters a standby state until the weight sensor detects the weight of the movable carrier. When the weight of the movable carrier is detected (S5), the processing device obtains a measurement value M that is a value obtained by subtracting the weight of the movable carrier from the weight. Next, the measured value M is divided by the weight b per article to calculate the total number of articles mounted on the movable carrier, and this is used as the quantity W of articles by the weight sensor (S6).

  Separately, the interrogator transmits an inquiry signal to the wireless tag of each article mounted on the movable carrier with a transmission output E = Ek (S7), receives a response signal from the wireless tag, The number of wireless tags received is counted to obtain the number T of wireless tags responding (S8). Next, the quantity W is compared with the quantity T to determine the magnitude relationship between the quantities (S9). If W> T, that is, if there is a wireless tag that has become a reading error in bidirectional communication, the transmission output E of the interrogator must be raised to prevent the reading error of the wireless tag. Therefore, first, it is checked whether or not E has reached the upper limit value Ej (S10). Here, when E = Ej, E has already reached the upper limit value, and the transmission output cannot be increased any more. Accordingly, the two-way communication with the wireless tag cannot be continued any more, a communication error is output (S11), and the two-way communication is terminated (or interrupted) (S21). On the other hand, if E = Ej is not satisfied, the transmission output E = Ek is increased by one level to E = Ek + 1, and at the same time, a = 0 is set (S12), and the process returns to step S7 again.

  If W> T is not satisfied in step S9 (W ≦ T), it is subsequently determined whether W = T (S13). Here, when W = T, bidirectional communication between the wireless tags of all articles mounted on the movable carrier and the interrogator has been established. Two-way communication is sequentially performed between them to manage the articles (S14). When the two-way communication with all the wireless tags is completed, since there is no reading error by the interrogator, the value of the parameter a is increased by 1, and a = a + 1 is set (S15). Here, it is determined whether or not the value of parameter a has reached N, which is a criterion for determining the number of consecutive bidirectional communications (S16). If a = N, the transmission output E = Ek is lowered by one step to E = Ek−1 and at the same time a = 0 (S17). If a does not reach N, the values of E and a are not changed. Finally, it is determined whether or not the interrogator has completed the management by the scheduled two-way communication with the wireless tags of all articles (S18). If the interrogator has been completed, the two-way communication is terminated (S21). . On the other hand, if it has not been completed, the process returns to step S5, and the interrogator enters a standby state until the weight sensor detects the weight of the next movable carrier.

  If W = T is not satisfied in step S13, that is, if W <T, the total number of wireless tags for which two-way communication with the interrogator is established rather than the number of articles mounted on the movable carrier. There will be more. Such a situation is mounted in the movable carrier because the transmission output E from the interrogator is too large than the proper output for good two-way communication with the wireless tag in this system. This is because two-way communication has been established with another wireless tag other than the communication target, which is different from the wireless tag attached to the article. In this state, it is impossible to manage the two-way communication with the wireless tag of each article in the movable carrier. Therefore, first, it is determined whether or not the transmission output E is the minimum value E1 (S19). If not, the transmission output E = Ek is lowered by one step to E = Ek-1, and at the same time a = 0. (S20). Thereafter, the process returns to step S7 again, and the inquiry signal is transmitted again from the interrogator to the wireless tag in a state where the transmission output E is lowered by one step.

  If E = E1 in step S19, the transmission output E cannot be lowered any more, so a communication error is output (S11), and the bidirectional communication is terminated (or interrupted) (S21). In this case, after reviewing the setting of the article management system, such as increasing the interval between movable carriers arranged adjacent to each other, the article management is started again from step S1. .

  With the above procedure, a system for managing articles can be operated by communication with a wireless tag attached to each. According to this procedure, when a reading mistake of the wireless tag occurs, the system detects that, and automatically increases the transmission output from the interrogator by one step and repeats it until the reading mistake is resolved. On the other hand, if good reading of the wireless tag without reading errors continues for a certain number of times, it is assumed that bidirectional communication with the wireless tag is sufficiently stable in the environment at that time, and the interrogator Is reduced by one step. Therefore, since the transmission output from the interrogator is automatically increased or decreased according to the situation, it is possible to always manage articles using wireless tags under the optimum communication conditions.

  As described above, in the article management system using the wireless tag reader according to the present invention, the weight of the article attached with the wireless tag is measured to calculate the number of wireless tags to be bidirectionally communicated, Using this, it is determined whether or not there is a radio tag that has been read incorrectly, and the transmission output from the interrogator is changed. By this method, reading errors of the wireless tag are eliminated, and good bidirectional communication can always be performed with the wireless tag to manage the article. Further, the above description is for explaining the effects in the case of the embodiment of the present invention, and thereby the invention described in the scope of the claims is limited or the scope of the claims is reduced. is not. Moreover, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim.

Schematic which shows the example of the management system of the articles | goods concerning embodiment of this invention. The flowchart which shows the example of the procedure of increase / decrease in the transmission output from an interrogator to a wireless tag. Schematic which shows the example of the management system of the articles | goods by the conventional radio | wireless tag.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Movable carrier 31 Carry case 12, 32 Goods 13, 33 Radio tag 14 Weight sensor 34 Weighing device 15 Floor surface 35a, 35b, 35c Belt conveyor 16, 36 Interrogator 17, 37 Processing apparatus S1-S21 Procedure

Claims (10)

A measuring means for measuring the total weight of an article to which a wireless tag is attached in a specific area;
Means for calculating the total number of the articles from the measured value of the total weight by the measuring means;
Means for transmitting an inquiry signal to each article from an interrogator and receiving a response signal from the wireless tag attached to each article;
From the response signal received by the interrogator, a calculation means for calculating the total number of wireless tags for which two-way communication has been established,
Setting means for setting the output of the interrogator based on the total number of articles calculated from the measured value of the total weight and the total number of wireless tags established by the two-way communication calculated from the response signal When,
An RFID tag reading apparatus comprising: an output adjusting unit that changes an output of the interrogator according to a set value of an output by the setting unit. Comparing the total number of articles calculated from the measured value of the total weight and the total number of wireless tags established by the two-way communication calculated from the response signal,
The total number of wireless tags established by the two-way communication calculated from the response signal is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. If below the maximum value, reset the output value of the interrogator to a higher value than before,
The wireless tag reader according to claim 1, wherein the output adjustment unit changes the output of the interrogator according to the reset value of the output. Comparing the total number of articles calculated from the measured value of the total weight and the total number of wireless tags established by the two-way communication calculated from the response signal,
The total number of wireless tags established by the two-way communication calculated from the response signal coincides with the total number of articles calculated from the measured value of the total weight, and the coincidence is set to a plurality of preset times. When the output of the interrogator is continuously obtained and exceeds the preset minimum value, the setting value of the output of the interrogator is reset to a lower value than before,
The wireless tag reading device according to claim 1 or 2, wherein the output adjustment unit changes the output of the interrogator according to a set value of the reset output. Comparing the total number of articles calculated from the measured value of the total weight and the total number of wireless tags established by the two-way communication calculated from the response signal,
The total number of wireless tags established by the two-way communication calculated from the response signal exceeds the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. When the minimum value is exceeded, reset the output value of the interrogator to a lower value than before,
4. The wireless tag reading device according to claim 1, wherein the output adjustment unit changes the output of the interrogator according to the reset setting value of the output. 5. When the weight of each of the articles is substantially equal to each other,
The wireless tag reader stores in advance the weight per piece of the article,
The means for calculating the total number of articles calculates the total number of the articles by dividing the total weight of the articles measured by the measuring means by the weight per one of the articles. The wireless tag reader according to any one of claims 1 to 4.   2. The article is collectively mounted on a movable carrier, and measuring means for measuring the total weight of the article is installed on a lower surface of a moving path through which the movable carrier passes. 6. The wireless tag reader according to any one of items 5 to 5.   The antenna that constitutes the interrogator and performs two-way communication with each wireless tag attached to the article is installed above a moving path through which the movable carrier passes. The wireless tag reading device according to 1. Measure the total weight of the article with the wireless tag attached in a specific area by measuring means,
From the total weight measured by the measuring means, the total number of the articles is calculated,
An inquiry signal is transmitted from the interrogator to each of the articles, and a response signal is received from the respective wireless tag attached to each of the articles.
From the response signal received by the interrogator, calculate the total number of wireless tags established bidirectional communication,
Comparing the total number of articles calculated from the measured value of the total weight with the total number of wireless tags established by the two-way communication calculated from the response signal;
The total number of wireless tags established by the two-way communication calculated from the response signal is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. If below the maximum value, reset the output value of the interrogator to a higher value than before,
The total number of wireless tags established by the two-way communication calculated from the response signal coincides with the total number of articles calculated from the measured value of the total weight, and the coincidence is set to a plurality of preset times. When the output of the interrogator is continuously obtained and exceeds the preset minimum value, the setting value of the output of the interrogator is reset to a lower value than before,
The total number of wireless tags established by the two-way communication calculated from the response signal exceeds the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. A wireless tag reading method, characterized in that when the minimum value is exceeded, the set value of the output of the interrogator is reset to a lower value than before. When the weight of each of the articles is substantially equal to each other,
The weight per one of the articles is measured in advance,
The means for calculating the total number of the articles calculates the total number of the articles by dividing the total weight of the articles measured by the measuring means by the weight per one of the articles. The wireless tag reading method according to claim 8. The total number of wireless tags established by the two-way communication calculated from the response signal is less than the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. When the output value of the interrogator is reset to a value higher than before when the output value of the interrogator is lower than the maximum value, the output adjustment means adjusts the output of the interrogator according to the reset setting value of the output. change,
The total number of wireless tags established by the two-way communication calculated from the response signal exceeds the total number of articles calculated from the measured value of the total weight, and the output of the interrogator is preset. When the output value of the interrogator is reset to a value lower than before, exceeding the minimum value, the output adjusting means adjusts the output of the interrogator according to the reset value of the output. change,
When the output of the interrogator is changed, the interrogator immediately transmits an inquiry signal to each article according to the changed output, and receives a response signal from each wireless tag attached to each article again,
The wireless tag reading method according to claim 8 or 9, wherein the total number of wireless tags for which two-way communication has been established is calculated again from the response signal received by the interrogator.

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