JP7589136B2 - Food Management System - Google Patents

Description

The present invention relates to a food ingredient management system.

In order to reduce food waste caused by excess food inventory, a food management system has been proposed in which RFID (Radio Frequency Identifier) tags are attached to food ingredients and inventory is managed based on the tag ID. For example, a method is known in which, in a household refrigerator, an RW antenna (reader/writer antenna) is provided for receiving food ingredients and an RW antenna for removing food ingredients is provided, and whether the food ingredient is being received or removed is determined based on which antenna reads the tag, and processing is performed accordingly.

There is also a system in which tags are attached to logistics cargo, and two or more RW antennas read the passing tags to determine whether the cargo passed through the gate in the outgoing or incoming direction. For example, Patent Document 1 describes a system in which two RW antennas provide two known coordinates, one RFID tag provides one unknown coordinate, for a total of three coordinates, and the unknown coordinates of the tag are calculated using the measured radio wave strength of each of the two RW antennas and a triangular formula, and the direction of movement is also determined.

JP 2018-169722 A

In home refrigerators, the installation space for antennas is limited from a design perspective, so it is important to install the two antennas, one for storing and one for discharging, close to each other. However, if the RW antenna for storing and the RW antenna for discharging are close to each other, it is easy for operational errors to occur when a tag is held upside down and the tag is read by the adjacent RW antenna. Since users hold up the food item with the tag upside down, the tag is not visible to the user, and there is a high possibility that the position where the tag is held upside down will be misaligned, especially when a small tag is attached to a large food item.

In addition, the technology described in the above-mentioned Patent Document 1 assumes that the tag moves within an area where the radio waves of the two RW antennas overlap at a distance of 1 m or more from the two RW antennas. Here, overlapping of radio waves of the RW antennas includes both cases, whether multiple RW antennas radiate radio waves simultaneously or multiple RW antennas radiate radio waves alternately. If the technology of Patent Document 1 is applied to a home refrigerator and the tag is moved at a distance away from the RW antenna to determine whether the tag is in or out based on the direction of movement, the radio waves may be reflected by the user's body when the tag is moved, interfering with the radio waves received by the tag. Furthermore, radio waves reflected from the surrounding environment, such as walls and tables around the refrigerator, metal racks, glass, and electromagnetic wave-blocking films, may also interfere. In this case, the strength of the radio waves received by the tag and the tag reflected radio waves received by the RW may suddenly increase or decrease significantly. In some cases, even though the radio wave strength should increase as the tag moves, the reflected radio waves from the surrounding area add radio waves of the opposite phase, resulting in a decrease in the combined received radio wave strength. In such cases, the direction of movement may be incorrectly determined.

The object of the present invention is to provide a food management system that can accurately determine whether an RFID-tagged food ingredient has been stored in or removed from a storage unit such as a home refrigerator.

To achieve the above-mentioned objective, the present invention provides a food management system for managing food stored in a storage facility, comprising an antenna that emits radio waves and a reader that reads RFID tags attached to food using signals received by the antenna, the antenna having multiple antennas capable of communicating with the RFID tags at near-field distances, and arranged so that the radio waves emitted by each antenna do not overlap at near-field distances, and the order in which the antennas read the RFID tags determines whether the food is being stored in or removed from the storage facility.

According to the present invention, it is possible to provide a food management system that can accurately determine whether an RFID-tagged food ingredient has been stored in or removed from a storage unit such as a home refrigerator. Problems, configurations, and effects other than those described above will become clear from the description of the embodiment of the invention below.

Bird's-eye view showing the structure of a refrigerator to which the food management system is applied Horizontal cross section showing the beam pattern of the RW antenna A graph showing the strength of radio waves received by the RW antenna and reflected by an RFID tag when the RFID tag is touched by a slide multiple times. Graph showing communication waveforms when the distance between the RW antenna and the RFID tag changes Flowchart showing the operation of the food management system Functional block diagram of a foodstuff management system according to a first embodiment of the present invention. A front view showing the flow of the first RW antenna, the second RW antenna, and the RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 7A. A front view showing the flow of the first RW antenna, the second RW antenna, and the RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 8A. A front view showing the flow of the first RW antenna, the second RW antenna, and the RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 9A. A front view showing the flow of the first RW antenna, the second RW antenna, and the RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 10A. A front view showing the flow of the first RW antenna, the second RW antenna, and the RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 11A. FIG. 1 is a top view showing the flow of a first RW antenna, a second RW antenna, and an RFID tag. Graph showing an RSSI waveform when an RFID tag is slide-touched like the flow line of FIG. 12A. A front view showing two flow paths of a first RW antenna, a second RW antenna, and an RFID tag. 13B is a graph showing an RSSI waveform when an RFID tag is slide-touched along the two flow lines in FIG. 13A, and a graph showing the tag reading timing of each antenna. A front view showing two flow paths of a first RW antenna, a second RW antenna, and an RFID tag. 14B is a graph showing an RSSI waveform when an RFID tag is slide-touched along the two flow lines in FIG. 14A, and a graph showing the tag reading timing of each antenna. FIG. 11 is a front view showing two flow lines of a first RW antenna, a second RW antenna, a third RW antenna, and an RFID tag in the second embodiment; 15B is a graph showing an RSSI waveform when an RFID tag is slide-touched along the two flow lines in FIG. 15A, and a graph showing the tag reading timing of each antenna. FIG. 11 is a front view showing two flow lines of a first RW antenna, a second RW antenna, a third RW antenna, and an RFID tag in the second embodiment; 16B is a graph showing an RSSI waveform when an RFID tag is slide-touched along the two flow lines in FIG. 16A, and a graph showing the tag reading timing of each antenna. FIG. 11 is a front view showing the flow of the first RW antenna, the second RW antenna, the third RW antenna, the fourth RW antenna, and the RFID tag in the second embodiment; FIG. 11 is a front view showing two flow lines of the first RW antenna, the second RW antenna, the third RW antenna, the fourth RW antenna, and the RFID tag in the second embodiment; FIG. 11 is a horizontal cross-sectional view showing the antenna planes of the first RW antenna and the second RW antenna according to the third embodiment. Functional block diagram of a foodstuff management system according to a fourth embodiment FIG. 11 is a front view showing three flow lines of the first RW antenna and the RFID tag according to the fourth embodiment; 21B is a graph showing an RSSI waveform when an RFID tag is slid and touched along the three flow lines in FIG. 21A, and a graph showing the tag reading timing of the first RW antenna. FIG. 11 is a front view showing three flow lines of the first RW antenna and the RFID tag according to the fourth embodiment; 22B is a graph showing an RSSI waveform when an RFID tag is slide-touched along the three flow lines in FIG. 22A, and a graph showing the tag reading timing of the first RW antenna. FIG. 13 is a diagram showing an antenna configuration according to a fifth embodiment;

The following describes embodiments of the present invention with reference to the drawings. The examples are illustrative for explaining the present invention, and some parts have been omitted or simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

In addition, in the embodiment of the invention, a refrigerator is used as an example, but other storage units such as storage shelves and storage units can also be used.

When there are multiple components with the same or similar functions, they may be described using the same reference numerals with different subscripts. Also, when there is no need to distinguish between these multiple components, the subscripts may be omitted.

In the embodiments, the processing performed by executing a program may be described. Here, the computer executes the program using a processor (e.g., CPU, GPU), and performs the processing defined by the program using storage resources (e.g., memory) and interface devices (e.g., communication ports). Therefore, the subject of the processing performed by executing the program may be the processor. Similarly, the subject of the processing performed by executing the program may be a controller, device, system, computer, or node having a processor. The subject of the processing performed by executing the program may be a calculation unit, and may include a dedicated circuit that performs specific processing. Here, the dedicated circuit is, for example, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a CPLD (Complex Programmable Logic Device).

The program may be installed on the computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and a storage resource that stores the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In addition, in the embodiment, two or more programs may be realized as one program, and one program may be realized as two or more programs.

The food ingredient management system according to this embodiment will be explained using FIG. 1.

Figure 1 is a bird's-eye view showing the structure of a refrigerator to which the foodstuff management system is applied. As shown in Figure 1, the refrigerator 1 body has a storage compartment door 9, which is provided with a first RW antenna 2 and a second RW antenna 3 that emit radio waves and receive radio waves reflected from an RFID tag 4 attached to foodstuff 5. From the viewpoints of design and space saving, the first RW antenna 2 and the second RW antenna 3 are built into the storage compartment door 9 or are placed on its surface with a distance of 1 to 2 cm between them. From the viewpoint of operability, each RW antenna is preferably placed at the waist height of a user of average height, for example, at the bottom of the refrigerator compartment door. Furthermore, from the viewpoint of reducing power consumption, each RW antenna may be set to emit radio waves only at a predetermined timing, triggered by the opening or closing of the storage compartment door 9 detected using a door switch, or by the user performing a predetermined operation.

Figure 2 is a horizontal cross-sectional view showing the beam pattern of the RW antenna. As shown in Figure 2, in the traffic path 8 of the RFID tag 4 passing near the exterior surface of the storage compartment door 9, the radio wave radiation area 6b of the first RW antenna 2 does not overlap with the radio wave radiation area 6 of the second RW antenna 3.

In addition, each RW antenna is covered with an electromagnetic wave-transmitting housing called a radome, and when applied to a refrigerator as in this embodiment, the resin part forming the exterior of the storage compartment door 9 plays the role of the radome. The exterior surface of the storage compartment door 9 and the RW antenna surface are positioned 1 cm to 5 cm apart.

When the user brings the RFID tag 4 close to the antenna installation surface so that it is at the shortest distance, the tag appears to be pressed against the exterior surface of the storage compartment door 9. When the user slides the RFID tag 4 in a straight line (slide touch) along the exterior surface while still pressing the RFID tag 4 against the surface, the RFID tag 4 moves from the outside to the inside of the beam pattern (effective radiation angle) of the RW antenna, and then moves from the inside to the outside. This slide touch action includes sliding the tag a few mm away from the exterior surface of the storage compartment door 9, and sliding it in a curved line several mm off the straight line.

Here, each RW antenna can communicate with the RFID tag 4 at a near-field distance (vertical distance of 1 to 5 cm from the antenna installation surface). That is, when the RFID tag 4 is at the near-field distance, the matching loss between the impedance of each RW antenna and the impedance of the reader/writer circuit is within the allowable value for communication (e.g., 10 dB), and the strength of the radio waves reflected by the RFID tag 4 and returned to the RW antenna is within the sensitivity that can be received by the reader/writer circuit. In addition, the effective radiation angle is set so that the radio waves radiated by each antenna do not overlap at the near-field distance. Therefore, at the position of the RFID tag 4 pressed against the exterior surface of the storage room door 9, the radio wave radiation areas of the first RW antenna 2 and the second RW antenna 3 do not overlap, preventing the occurrence of reading errors.

Figure 3 is a graph showing the strength of radio waves reflected by the RFID tag 4 and received by the RW antenna when the RFID tag 4 is touched and slid multiple times. Figure 3 shows that the strength of the radio waves received by the RW antenna repeatedly changes sharply each time the RFID tag 4 is slid parallel to the installation surface of the RW antenna.

Figure 4 is a graph showing the communication waveform when the distance between the RW antenna and the RFID tag 4 changes. The radio waves received by the RFID tag 4 show a radio wave envelope that is inversely proportional to the load modulation signal and the change in distance. Normally, the rate of radio wave intensity fluctuation when the RFID tag 4 is moved by hand is about a few Hz, which means that the RFID tag 4 can be moved repeatedly several times per second. This rate is not suitable for general information transmission, but is fast enough to be used as a trigger for switching the operating mode of a reader/writer. Note that the operation of repeatedly changing the distance between the RW antenna and the RFID tag 4 also includes the operation of pressing the RFID tag 4 against the exterior surface of the RW antenna and sliding it multiple times to touch it.

Figure 5 is a flow chart showing the operation of the foodstuff management system. After the power of the refrigerator 1 main body is turned on (step S100), the reader/writer waits for a reflected radio wave to be returned from the RFID tag 4 (step S101). When the radio wave is reflected back from the RFID tag 4, the received data is stored in a buffer (step S102).

Next, it is determined whether the time interval for reading the RFID tag 4 by the reader/writer satisfies a predetermined condition, that is, whether it is less than a first predetermined time (e.g., 2 seconds) and more than a second predetermined time (e.g., 100 milliseconds) (step S103). If the predetermined condition is not met in step S103, it is determined to be an error, and the reader/writer returns to a state of waiting for the reflected radio wave from the RFID tag 4 (step S101). On the other hand, if the predetermined condition is met in step S103, it is determined to be normal, and the process proceeds to the next step S104. In practice, since the reading of the RFID tag 4 must be performed within a finite time, in step S104, it is determined whether the total time for repeatedly reading the RFID tag 4 is within a set time limit (e.g., 10 seconds). If the total time exceeds the time limit in step S104, it is determined to be an error, all the received data stored in the buffer is cleared, and the reader/writer returns to a state of waiting for the reflected radio wave from the RFID tag 4 (step S101). On the other hand, if the total time is within the time limit in step S104, it is determined to be normal and the process proceeds to the next step S105.

In step S105, the order in which the antennas read the RFID tag 4, the time interval between the time when the RFID tag 4 was read previously and the time when the RFID tag 4 was read subsequently, and the number of times each antenna was repeatedly slid and touched are detected from the received data stored in the buffer.

Here, the reading time interval of the RFID tag 4 changes depending on the movement speed of the user's slide touch; for example, if the movement speed is changed from "fast" to "slow" to "fast" with each touch, the time interval is detected as "short" to "long" to "short", and a pattern of changing time interval length can be generated according to the user's tag operation. Based on the time series data of the reading time interval detected in this way, the time interval is binarized into "long" and "short" or converted into three values into "long", "medium" and "short" which may be referred to below as quantization of the time interval.

The antenna order, time interval, and number of touches detected in step S105 can be used as triggers to branch the process. For example, two touches can be used as a trigger to execute "writing tag ID to database," and three touches can be used as a trigger to execute "deleting tag ID information from database."

Next, it is determined whether the RW antenna of the RFID tag 4 has been touched two or more times (step S106). If the number of touches is less than two in step S106, it is determined to be an error, and the reader/writer returns to a state of waiting for the reflected radio waves from the RFID tag 4 (step S101). This is because a single touch is considered to be an unintended read. On the other hand, if the number of touches is two or more in step S106, it is determined to be normal, and the process proceeds to the next step S107.

In step S107, parameters and flags are initialized. After that, in step S108, feature information is extracted from the received data using past information stored in the past information storage unit 17 described later. Examples of feature information include an approximation value including the maximum value of RSSI (Received Signal Strength Indicator) and its time, an approximation value including the minimum value of RSSI and its time, an approximation value including a local maximum value of RSSI and its time, an approximation value including a local minimum value of RSSI and its time, an average value of RSSI, a time differential value of RSSI, a change in the frequency of the received radio wave (constant, increasing, decreasing), a time difference from the time of an approximation value including the maximum value when a certain RW antenna reads an RFID tag 4 to the time of an approximation value including the maximum value when the same or another RW antenna reads an RFID tag 4, a long, medium, or short change pattern of the tag reading time interval, etc. The reason we use approximate values here is that signals vary due to the effects of thermal noise in the circuit, radio interference from the surroundings, and the distortion characteristics of the radio wave propagation path, so when the signal waveform is shaped or filtered, the maximum value of the raw data may differ from the maximum value point after signal processing.

Next, the feature information extracted in step S108, the antenna order detected in step S105, the read time interval, the number of touches, etc. are integrated and compared as feature information with the command table (step S110). The command table is composed of feature information items, mode classifications, and task classifications. Here, the mode classifications are classifications that define the granularity of processing at the mode level, such as "write to the server database," "read from the server database," "delete data from the server database," and "display on a display device." And the task classifications are classifications that define the granularity of processing at the task level, such as "write the food name to the database," "write the expiration date," and "read calories."

In step S110, the characteristic information and the like are used as input information to check against the command table, and it is determined which task classification should be processed in which mode classification, and the corresponding classification flag is set to 1 in the internal parameters held by the reader/writer (step S111). If the antenna order is checked as input information and the antenna order detected in step S105 is not defined in the command table, it can be estimated that the movement of the slide touch deviates from the specified tag movement line and the RFID tag 4 is not read. In this case, the last read antenna information is sequentially excluded, and when a good pattern of repeated slide touch is obtained, that is, the same as the antenna order defined in the command table, this may be used as an estimated pattern. The intention of sequentially excluding the last read antenna information is that after the repeated slide operation of the slide touch is completed, the RFID tag 4 may be moved carelessly, resulting in the RFID tag 4 being read due to an operational error. By performing such an erroneous input estimation, operability is improved.

In addition, when the reading time interval is referenced as input information, the time series data of the quantized time interval "long" or "short" or "long", "medium", or "short" is compared with the instruction table to determine which task classification should be processed and executed in which mode classification.

First, it is determined whether the classification flag A is 1 (step S112). If it is determined in step S112 that the classification flag A is 1, process A is executed (step S116), and the process returns to the state of waiting for the reflected radio wave of the RFID tag 4 (step S101). On the other hand, if it is determined in step S112 that the classification flag A is not 1, then it is determined whether the classification flag B is 1 (step S113). If it is determined in step S113 that the classification flag B is 1, process B is executed (step S117), and the process returns to the state of waiting for the reflected radio wave of the RFID tag 4 (step S101). On the other hand, if it is determined in step S113 that the classification flag B is not 1, then it is determined whether the classification flag C is 1 (step S114). If it is determined in step S114 that the classification flag C is 1, process C is executed (step S118), and the process returns to the state of waiting for the reflected radio wave of the RFID tag 4 (step S101). On the other hand, if it is determined in step S114 that the classification flag C is not 1, then it is determined whether or not the classification flag D is 1 (step S115). If it is determined in step S115 that the classification flag D is 1, process D is executed (step S119) and the process returns to the state of waiting for the reflected radio wave from the RFID tag 4 (step S101). On the other hand, if it is determined in step S115 that the classification flag D is not 1, the process is not executed and the process returns to the state of waiting for the reflected radio wave from the RFID tag 4 (step S101).

Figure 6 is a functional block diagram of the foodstuff management system according to the first embodiment. As shown in Figure 6, the foodstuff management system of this embodiment is composed of a first RW antenna 2, a second RW antenna 3, an RFID reader/writer 12, a control computer 24, an Internet communication network 151, and a database server 31. Note that the RFID reader/writer 12 only needs to have the function of reading information from a tag, and does not necessarily need to have the function of writing information to the tag.

The RFID reader/writer 12 includes a high-frequency processing unit 11, a baseband signal processing unit 20, and a reader/writer communication I/F unit 22. The high-frequency processing unit 11 down-converts the frequency of the reflected radio waves returned by the RFID tag 4 and received by the first RW antenna 2 or the second RW antenna 3, and sends the down-converted frequency to the baseband signal processing unit 20.

The baseband signal processing unit 20 includes an RSSI detection unit 13, an ID code detection unit 14, a sequence end determination unit 15, a feature extraction unit 16, a past information storage unit 17, a sequence detection unit 18, a command determination unit 19, a first command table storage unit 26a, and a branch processing unit 21. The RSSI detection unit 13 detects the RSSI of the received radio waves. The ID code detection unit 14 reads the ID code of the RFID tag 4 from the received radio waves.

The sequence end determination unit 15 has a time interval detection unit 15a that detects the time interval between reading the RFID tag 4, and a time interval quantization unit 15b that quantizes the time interval detected by the time interval detection unit 15a. Furthermore, if the RFID tag 4 is not read again even after a first predetermined time has elapsed since the RFID tag 4 was last read, the sequence end determination unit 15 determines that a series of input sequences by the user of the RFID tag 4 has ended. Furthermore, if the RFID tag 4 is read before a second predetermined time has elapsed since the RFID tag 4 was last read, the sequence end determination unit 15 determines that the input is incorrect, and the RFID reader/writer 12 returns to a state of waiting for the reflected radio waves from the RFID tag 4.

The feature extraction unit 16 extracts the aforementioned feature information, such as an approximate value including the maximum RSSI value and its time, from the received data. The past information storage unit 17 stores data models created from past read data and profile information statistically extracted (average, variance, maximum, minimum, etc.) from read data for each communication environment and condition. The feature extraction unit 16 can read out this past information from the past information storage unit 17 and use it for maximum likelihood estimation of the received data.

The order detection unit 18 detects the order in which the antennas read the RFID tags 4 using information from the feature extraction unit 16 and the past information storage unit 17.

The first command table storage unit 26a sends out a command table, which is information written in a memory area mounted on the RFID reader/writer 12, in response to a request from the command determination unit 19. Here, in the command table, multiple commands, including the storage and removal of ingredients, are predefined for multiple antenna sequences. The command table stored in the first command table storage unit 26a of the RFID reader/writer 12 has the same task classification as the command table stored in the second command table storage unit 26b of the control computer 24. The first command table storage unit 26a defines the execution processing tasks of the RFID reader/writer 12 corresponding to each task classification, and commands for requesting tasks to be processed by the control computer 24 in each task classification. On the other hand, the second command table storage unit 26b defines the execution processing tasks of the control computer 24 corresponding to each task classification, and information for identifying the processing request command of the RFID reader/writer 12 corresponding to each task classification, such as the command ID code and the command packet length. Note that the instruction table may include task classifications that are further subdivided according to variations in quantized read time intervals, rather than simply by antenna order.

The command determination unit 19 checks the command table, which is information sent after requesting data from the first command table storage unit 26a, based on the antenna order detected by the order detection unit 18 and the feature information extracted by the feature extraction unit 16, and determines the command corresponding to the antenna order, etc., i.e., which task classification and mode classification it corresponds to.

Based on the mode classification determined by the command determination unit 19, the branch processing unit 21 changes the internal parameters of the RFID reader/writer 12 to switch modes in accordance with the control protocol implemented in the RFID reader/writer 12, and executes processing tasks classified within the range of each mode.

The reader/writer communication I/F unit 22 receives command signals and information from the control computer 24 that controls the RFID reader/writer 12, and transmits information about the RFID tag 4 read by the RFID reader/writer 12 and data that has been baseband processed from the information to the control computer 24.

The control computer 24 includes an RW communication I/F unit 23, a CPU 25, a second command table storage unit 26b, a network communication I/F unit 27, and a display device 28. The control computer 24 may be installed in a mobile terminal or a refrigerator.

The RW communication I/F unit 23 receives information about the read RFID tag 4 sent from the RFID reader/writer 12, response information to commands issued by the control computer 24, and the like, and also transmits signals and information that serve as commands for controlling the RFID reader/writer 12.

The CPU 25 receives the tag information, baseband processed data, mode classification information and task classification information defined in the command table, and a processing request command sent from the RFID reader/writer 12. Here, a protocol for understanding commands from the RFID reader/writer 12 requesting a processing task is implemented in the CPU 25 and its associated storage device. When the CPU 25 receives a command, it compares the command table, which is information sent after requesting data from the second command table storage unit 26b, with the request command to determine which mode classification and task classification it corresponds to, and executes the processing defined in the command table for the corresponding task classification.

For example, when writing is required in the database processing unit 30 of the database server 31, the CPU 25 sends the data to be written to the network communication I/F unit 27. The network communication I/F unit 27 then converts the received data into a communication packet format, such as TCP/IP format, and transmits the TCP/IP packet to the network communication I/F unit 29 of the database server 31 via the Internet communication network 151. The network communication I/F unit 29 of the database server 31 extracts the data to be written from the received packet and transmits it to the database processing unit 30, which writes the received data to the database. The CPU 25 can also read or erase the relevant data from the database in a similar manner.

As an example, we will explain a case where the mode classification information and task classification information received by the control computer 24 from the RFID reader/writer 12 indicate changing the output destination to the display device and sending the read information on the food name and calories of the ingredients, respectively. In this case, the CPU 25 sends text data on the food name and calorie information of the ingredients, and layout information that defines the size, position, and color of this text data, to the display device 28. The display device 28 converts the received text data and layout information into two-dimensional pixel information, and outputs an image including the food name and calorie information of the ingredients to a display device such as a liquid crystal panel.

In addition, when multiple users, such as a family, use one refrigerator, it is possible to associate who has put in and taken out what ingredients, so that ingredients can be managed on an individual basis. Therefore, several examples of the method for identifying individuals in this embodiment will be described.

The first method uses an RFID tag (hereinafter sometimes referred to as a personal identification tag) that identifies an individual, separate from the RFID tag 4 (hereinafter sometimes referred to as a food tag) attached to the food. In this method, first, the relationship information linking the individual's name and the ID of the personal identification tag is stored in both the first command table storage unit 26a of the RFID reader/writer 12 and the second command table storage unit 26b of the control computer 24. The user then combines the two tags, the personal identification tag and the food tag, and has the RFID reader/writer 12 read them. The RFID reader/writer 12 then calls up the name defined by the personal identification tag ID from the first command table storage unit 26a to the command determination unit 19, collates it with the received data, selects a process, and executes it. At this time, the control computer 24 calls up the name defined by the personal identification tag ID from the second command table storage unit 26b to the CPU 25, collates it, and selects a process.

The second method is to assign a specific user to a specific tag operation (antenna order, reading time interval, number of touches, etc.). In this method, information linking an individual's name with a specific tag operation is stored in the first command table storage unit 26a and the second command table storage unit 26b.

The third method is to have AI (artificial intelligence) learn the RSSI data from tag readings for each individual user in advance, and then identify the individual from the characteristic information of the RSSI when the RFID tag 4 is read.

The following describes, with reference to Figures 7A to 14B, how the order detection unit 18 detects the antenna order when the RFID tag 4 is slid and touched in various trajectories in the foodstuff management system of this embodiment.

Figure 7A is a front view showing the first RW antenna 2, the second RW antenna 3, and the flow line 32 of the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or placed on the surface of the storage door of the refrigerator 1 body, and the RFID tag 4 is attached to the surface of a large food ingredient 5, and as shown in Figure 7A, the flow line 32 of the tag moving horizontally around the center of the RW antenna is shown. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and while pressing the RFID tag 4 against the exterior surface of the storage compartment door 9, slides it linearly along the exterior surface of the door. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss between the antenna impedance of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the allowable range for communication. Also, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the RFID reader/writer 12 circuit and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 7B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the flow line 32 in Figure 7A. First, as the RFID tag 4 moves straight from the outside to the inside of the first RW antenna 2, the RSSI, which indicates the strength of the radio waves received by the first RW antenna 2, gradually increases, and reaches a peak when the RFID tag 4 reaches the center of the first RW antenna 2. Next, as the RFID tag 4 moves from the center of the first RW antenna 2 to the outside to the right, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases, and reaches a peak when the RFID tag 4 reaches the center of the second RW antenna 3. Furthermore, as the RFID tag 4 moves from the center of the second RW antenna 3 to the outside to the right, the RSSI of the second RW antenna 3 decreases. In this way, the first RW antenna 2 and the second RW antenna 3 both produce mountain-shaped RSSI waveforms due to the movement of the RFID tag 4, and the time at which each peak occurs can be determined, and the order in which the RW antennas read the RFID tag 4. Therefore, even if the trajectory of the RFID tag 4 deviates from the center of the RW antenna, the strength of the RSSI received by the RW antenna varies over time, making it possible to identify the timing at which the RFID tag 4 was held up and the order in which the RW antennas read it. As a result, it becomes possible to correctly determine the command (e.g., enter or exit) corresponding to the antenna order without being affected by radio wave reflections caused by users or objects around the refrigerator.

Figure 8A is a front view showing the flow line 37 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or arranged on the surface of the storage compartment door 9 of the refrigerator 1 body, the RFID tag 4 is attached to the surface of a large food ingredient 5, and as shown in Figure 8A, the flow line 37 of the tag moving horizontally along the lower end of the RW antenna is shown. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and while pressing the RFID tag 4 against the exterior surface of the storage compartment door 9, slides it linearly along the exterior surface of the door. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss between the antenna impedance of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the allowable range for communication. Also, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the RFID reader/writer 12 circuit and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 8B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the flow line 37 in Figure 8A. First, as the RFID tag 4 moves straight from the outer left bottom end of the first RW antenna 2 to the inner side, the RSSI, which indicates the strength of the received radio wave of the first RW antenna 2, gradually increases and reaches a peak when the RFID tag 4 reaches the center bottom end of the first RW antenna 2. Next, as the RFID tag 4 moves from the center bottom end of the first RW antenna 2 to the outer right bottom end, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases and reaches a peak when the RFID tag 4 reaches the center bottom end of the second RW antenna 3. Furthermore, as the RFID tag 4 moves from the center bottom end of the second RW antenna 3 to the outer right bottom end, the RSSI of the second RW antenna 3 decreases. In this way, the peaks of the RSSI of the first RW antenna 2 and the second RW antenna 3 are both smaller than the peak in FIG. 7B, but the movement of the RFID tag 4 creates a mountain-shaped waveform in the RSSI. Therefore, it is possible to determine the time when the RSSI of the first RW antenna 2 and the RSSI of the second RW antenna 3 each reach their peak, and also the order in which the RW antennas read the RFID tag 4.

Figure 9A is a front view showing the flow line 42 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or arranged on the surface of the storage compartment door 9 of the refrigerator 1 body, and the RFID tag 4 is attached to the surface of a large food ingredient 5. As shown in Figure 9A, the flow line 42 of the tag moving diagonally from the bottom end of the RW antenna to the center of the antenna adjacent to the right is shown. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and while pressing the RFID tag 4 against the exterior surface of the storage compartment door 9, slides it linearly on the exterior surface of the door. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss between the antenna impedance of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the allowable range for communication. Also, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the RFID reader/writer 12 circuit and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 9B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the movement line 42 in Figure 9A. First, when the RFID tag 4 moves straight from the lower end of the first RW antenna 2 diagonally upward to the right, the RSSI, which indicates the strength of the radio waves received by the first RW antenna 2, gradually increases and reaches a peak when the RFID tag 4 approaches the center of the first RW antenna 2. Next, as the RFID tag 4 moves from the lower end of the center of the first RW antenna 2 to the outer right, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases and reaches a peak when the RFID tag 4 reaches the center of the second RW antenna 3. Furthermore, as the RFID tag 4 moves from the center of the second RW antenna 3 to the upper outer right end, the RSSI of the second RW antenna 3 decreases. In this way, a mountain-shaped waveform of the RSSI is generated by the movement of the RFID tag 4 in both the first RW antenna 2 and the second RW antenna 3. Therefore, it is possible to determine the time when the RSSI of the first RW antenna 2 and the RSSI of the second RW antenna 3 each reach their peak, and also to determine the order in which the RW antennas read the RFID tags 4. Note that there is a significant difference between the RSSI peak of the first RW antenna 2 and the RSSI peak of the second RW antenna 3, with the latter being larger, but the magnitude of the peak value does not matter.

Figure 10A is a front view showing the movement line 47 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or arranged on the surface of the storage compartment door 9 of the refrigerator 1 body, and the RFID tag 4 is attached to the surface of a large food ingredient 5. As shown in Figure 10A, the movement line 47 of the tag moving diagonally from the center of the RW antenna to the top end of the antenna adjacent to the right is shown. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and while pressing the RFID tag 4 against the exterior surface of the storage compartment door 9, slides it linearly on the exterior surface of the door. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss between the antenna impedance of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the allowable range for communication. Also, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the RFID reader/writer 12 circuit and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 10B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the movement line 47 in Figure 10A. First, when the RFID tag 4 moves straight from the lower outer left end of the first RW antenna 2 to the upper right diagonally, the RSSI, which indicates the strength of the radio waves received by the first RW antenna 2, gradually increases and reaches a peak when the RFID tag 4 reaches the center of the first RW antenna 2. Next, as the RFID tag 4 moves from the center of the first RW antenna 2 to the upper outer right end, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases and reaches a peak when the RFID tag 4 reaches the upper center end of the second RW antenna 3. Furthermore, as the RFID tag 4 moves from the upper center end of the second RW antenna 3 to the outer right end, the RSSI of the second RW antenna 3 decreases. In this way, a mountain-shaped RSSI waveform is generated by the movement of the RFID tag 4 in both the first RW antenna 2 and the second RW antenna 3. Therefore, it is possible to determine the time when the RSSI of the first RW antenna 2 and the RSSI of the second antenna each reach their peak, and also to determine the order in which the RW antennas read the RFID tags 4. Note that the RSSI peak of the first RW antenna 2 is larger than that of the second RW antenna 3, showing a significant difference, but the magnitude of the peak value does not matter.

Figure 11A is a front view showing the first RW antenna 2, the second RW antenna 3, and the flow line 52 of the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or arranged on the surface of the storage compartment door 9 of the refrigerator 1 body, and the RFID tag 4 is attached to the surface of a large food ingredient 5. As shown in Figure 11A, the tag flow line 52 is shown drawing an arc from the lower left end of the RW antenna to the lower right end of the antenna adjacent to the right. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and slides the RFID tag 4 in an arc while pressing it against the exterior surface of the storage compartment door 9. In other words, even if the user does not intend to move the RFID tag 4 in an arc, it may move in a curved trajectory to ease the range of motion of the joints of the hand and arm. However, even in such a case, the matching loss between the impedance of the antenna of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the range of the allowable value for communication. Furthermore, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the circuit of the RFID reader/writer 12 and within the range of values allowed for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 11B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the movement line 52 in Figure 11A. First, when the RFID tag 4 draws an arc from the outer lower left end of the first RW antenna 2 diagonally upward to the right, the RSSI, which indicates the strength of the radio waves received by the first RW antenna 2, gradually increases and reaches a peak when the RFID tag 4 approaches the center of the first RW antenna 2. Next, as the RFID tag 4 approaches the boundary with the antenna to the right from near the center of the first RW antenna 2, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases and reaches a peak when the RFID tag 4 approaches the center of the second RW antenna 3. Furthermore, as the RFID tag 4 draws an arc from near the center of the second RW antenna 3 to the outer lower right end, the RSSI of the second RW antenna 3 decreases. In this way, even if the movement line 52 of the RFID tag 4 is an arc-shaped trajectory, the movement of the RFID tag 4 generates a mountain-shaped waveform in the RSSI of both the first RW antenna 2 and the second RW antenna 3. Therefore, it is possible to determine the time when the RSSI of the first RW antenna 2 and the RSSI of the second RW antenna 3 each reach their peak, and also to determine the order in which the RW antennas read the RFID tag 4.

Figure 12A is a top view (a plan view seen from above in the vertical direction) showing the movement line 57 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The first RW antenna 2 and the second RW antenna 3 are built into or placed on the surface of the storage compartment door 9 of the refrigerator 1 body, and the RFID tag 4 is attached to the surface of a large food ingredient 5. As shown in Figure 12A, the tag's movement line 57 moves in an arc from the left outer front of the RW antenna to the back position of the boundary between the two antennas, and then moves from the back position to the right outer front of the adjacent antenna. The user faces the side of the food ingredient 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and slides the RFID tag 4 on the exterior surface of the storage compartment door 9 while pressing it against the exterior surface of the door. In other words, even if the user does not intend to move the RFID tag 4 in an arc, it may move in a curved trajectory to ease the range of motion of the joints of the hand and arm. However, even in such a case, the matching loss between the antenna impedance of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the allowable range for communication. Also, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the RFID reader/writer 12 circuit and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 12B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as shown by the movement line 57 in Figure 12A. First, as the RFID tag 4 moves in an arc from the front left outside of the first RW antenna 2 toward the boundary between the two antennas, the RSSI, which indicates the strength of the radio waves received by the first RW antenna 2, gradually increases and reaches a peak when the RFID tag 4 approaches the center of the first RW antenna 2. Next, as the RFID tag 4 moves from near the center of the first RW antenna 2 toward the boundary with the antenna next to it on the right, the RSSI of the first RW antenna 2 decreases, but the RSSI of the second RW antenna 3 gradually increases and reaches a peak when the RFID tag 4 approaches the center of the second RW antenna 3. Furthermore, as the RFID tag 4 moves in an arc from near the center of the second RW antenna 3 toward the front right outside, the RSSI of the second RW antenna 3 decreases. In this way, even if the movement line 57 of the RFID tag 4 is an arc-shaped trajectory, the movement of the RFID tag 4 generates a mountain-shaped waveform in the RSSI of both the first RW antenna 2 and the second RW antenna 3. Therefore, it is possible to determine the time when the RSSI of the first RW antenna 2 and the RSSI of the second RW antenna 3 each reach their peak, and also the order in which the RW antennas read the RFID tag 4.

Figure 13A is a front view showing the flow lines 64 and 65 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The flow line 64 of the RFID tag 4 shows the first of two sliding flow lines (outward-outward) passing from the first RW antenna 2 to the second RW antenna 3. The flow line 65 of the RFID tag 4 shows the second of two sliding flow lines (outward-outward) passing from the first RW antenna 2 to the second RW antenna 3. That is, the series of input sequences shown in Figure 13A includes multiple (two) input sequences with the same antenna order. The user faces the side of the food material 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and slides the RFID tag 4 linearly along the exterior surface of the door while pressing it against the exterior surface of the storage chamber door 9. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss of the impedance of the antenna of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the range of allowable values for communication. In addition, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the circuit of the RFID reader/writer 12 and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 13B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as in the flow line 64 and the flow line 65 of Figure 13A, and a graph showing the tag reading timing of each antenna. The RFID reader/writer 12 and the control computer 24 determine the timing when each antenna reads the RFID tag 4 from the peak of the RSSI waveform of the first RW antenna 2 and the second RW antenna 3. Here, as described above, if the RFID tag 4 is read again before the first predetermined time has elapsed since the last reading, it is regarded as a series of input sequences, and the reading of the RFID tag 4 by the RFID reader/writer 12 continues. In Figure 13B, since the first RW antenna 2 corresponding to the second flow line 65 is read for the second time before the first predetermined time has elapsed after the first reading of the second RW antenna 3 corresponding to the first flow line 64, the two slide flow lines are regarded as one input sequence. Therefore, even if slide touches are repeated multiple times in the same direction, it is possible to determine the order in which all RW antennas read RFID tags 4.

Figure 14A is a front view showing the flow lines 68 and 69 of the first RW antenna 2, the second RW antenna 3, and the RFID tag 4. The flow line 68 of the RFID tag 4 is the first of two sliding flows (outward-inward) from the first RW antenna 2 to the second RW antenna 3, and proceeds from the first RW antenna 2 to the second RW antenna 3. The flow line 69 of the RFID tag 4 is the second of two sliding flows (outward-inward) from the first RW antenna 2 to the second antenna, and proceeds from the second RW antenna 3 to the first RW antenna 2. That is, the series of input sequences shown in Figure 14A includes multiple (two) input sequences in which the antenna order is reversed. The user faces the side of the food material 5 to which the RFID tag 4 is attached toward the first RW antenna 2, and slides the RFID tag 4 linearly along the exterior surface of the door while pressing it against the exterior surface of the storage chamber door 9. That is, an operation slide touch is performed in which the RFID tag 4 moves linearly from the outside to the inside of the first RW antenna 2 and from the inside to the outside so as to pass through the center of the first RW antenna 2, and then moves linearly from the outside to the inside of the second RW antenna 3 and from the inside to the outside so as to pass through the center of the second RW antenna 3. At this time, the matching loss of the impedance of the antenna of the RFID tag 4 passing close to the first RW antenna 2 and the second RW antenna 3 and the impedance of the reader/writer circuit is within the range of allowable values for communication. In addition, the strength of the radio waves reflected by the RFID tag 4 and received by the first RW antenna 2 and the second RW antenna 3 is within the reception sensitivity range of the circuit of the RFID reader/writer 12 and within the range of values allowable for communication. Therefore, the RFID reader/writer 12 can read the RFID tag 4 and can identify the order of the RW antennas over which the RFID tag 4 was held.

Figure 14B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as in the movement lines 68 and 69 of Figure 14A, and a graph showing the tag reading timing of each antenna. The RFID reader/writer 12 and the control computer 24 determine the timing at which each antenna reads the RFID tag 4 from the peaks of the RSSI waveforms of the first RW antenna 2 and the second RW antenna 3. In Figure 14B, the second RW antenna 3 corresponding to the movement line 69 is read for the second time before the first predetermined time has elapsed after the first reading of the second RW antenna 3 corresponding to the movement line 68, so the two sliding movement lines are considered to be one input sequence. Therefore, even if the sliding touch is repeated in the opposite direction, it is possible to determine all the sequences of the RW antennas that read the RFID tag 4.

As described above with reference to Figures 7A to 14B, this embodiment can detect the order in which the antennas read the RFID tags 4, making it possible to determine the direction of the slide touch. Therefore, even if multiple RW antennas are arranged side by side in a limited space, highly accurate input can be achieved.

Example 2 is an example of a food management system that increases the variety of the sequence patterns of the RW antennas over which the RFID tag 4 is held by using three or more RW antennas. In this example, the number of processing branches of the RFID reader/writer 12 can be increased, so the number of command options also increases. Note that the spacing between the RW antennas may be uneven.

Figure 15A is a front view showing the movement lines 73 and 74 of the first RW antenna 2, the second RW antenna 3, the third RW antenna 72, and the RFID tag 4. The movement line 73 of the RFID tag 4 shows the first of two sliding movement lines (outward path-outward path) that pass from the first RW antenna 2 to the third RW antenna 72. The movement line 74 of the RFID tag 4 shows the second of two sliding movement lines (outward path-outward path) that pass from the first RW antenna 2 to the third RW antenna 72.

Figure 15B is a graph showing the RSSI waveform when the RFID tag 4 is slid and touched as in the flow lines 73 and 74 of Figure 15A, and a graph showing the tag reading timing of each antenna. The RFID reader/writer 12 and the control computer 24 determine the timing at which each antenna reads the RFID tag 4 from the peaks of the RSSI waveforms of the first RW antenna 2, the second RW antenna 3, and the third RW antenna 72. In Figure 15B, the first RW antenna 2 corresponding to the flow line 74 is read for the second time before the first predetermined time has elapsed after the third RW antenna 72 corresponding to the first flow line 73 is read, so the two slide flow lines are considered to be one input sequence. Therefore, it is possible to determine all the sequences of the RW antennas that read the RFID tag 4.

Figure 16A is a front view showing the movement lines 78 and 79 of the first RW antenna 2, the second RW antenna 3, the third RW antenna 72, and the RFID tag 4. The movement line 78 of the RFID tag 4 shows the first of two sliding movement lines (outward-inward) going back and forth from the first RW antenna 2 to the third RW antenna 72, proceeding from the first RW antenna 2 to the third RW antenna 72. The movement line 79 of the RFID tag 4 shows the second of two sliding movement lines (outward-inward) going back and forth from the first RW antenna 2 to the third RW antenna 72, proceeding from the third RW antenna 72 to the first RW antenna 2.

Figure 16B is a graph showing the RSSI waveform when the RFID tag 4 is slid and touched as in the movement lines 78 and 79 of Figure 16A, and a graph showing the tag reading timing of each antenna. The RFID reader/writer 12 and the control computer 24 determine the timing at which each antenna reads the RFID tag 4 from the peaks of the RSSI waveforms of the first RW antenna 2, the second RW antenna 3, and the third RW antenna 72. In Figure 16B, the third RW antenna 72 corresponding to the second movement line 79 is read before the first predetermined time has elapsed after the first reading of the third RW antenna 72 corresponding to the first movement line 78, so the two sliding movement lines are considered to be one input sequence. Therefore, it is possible to determine all the sequences of the RW antennas that read the RFID tag 4.

Figure 17 is a front view showing the first RW antenna 2, the second RW antenna 3, the third RW antenna 72, the fourth RW antenna 94, and the flow line 119 of the RFID tag 4. In the flow line 119 of the RFID tag 4, the RFID tag 4 first moves from the first RW antenna 2 to the second RW antenna 3, then moves from the second RW antenna 3 to the third RW antenna 72, and further moves from the third RW antenna 72 to the fourth RW antenna 94. In this way, even when there are four RW antennas, the RFID reader/writer 12 can identify the timing at which the RFID tag 4 was read and the order of the antennas that read it.

Figure 18 is a front view showing the first RW antenna 2, the second RW antenna 3, the third RW antenna 72, the fourth RW antenna 94, and the flow lines 120 and 121 of the RFID tag 4. In the flow line 120 of the RFID tag 4, the RFID tag 4 moves from the first RW antenna 2 to the fourth RW antenna 94, and in the flow line 121 of the RFID tag 4, the RFID tag 4 moves from the second RW antenna 3 to the third RW antenna 72. In this way, even when there are four RW antennas, the RFID reader/writer 12 can identify the timing at which the RFID tag 4 was read and the order of the antennas that read it.

In this embodiment, an example in which the number of RW antennas is three is described in Figs. 15A to 16B, and an example in which the number of RW antennas is four is described in Figs. 17 and 18, but the number of RW antennas may be five or more. In either case, the variation in the antenna order that can be read can be increased, making it possible to enrich the variety of commands.

In Example 3, instead of arranging the two RW antennas on the same plane parallel to the exterior surface of the storage compartment door 9, the two RW antennas are tilted outward, i.e., tilted in such a way that the radio waves radiated from each RW antenna move away from each other. By arranging the antennas in this way, the overlapping area of the radio waves radiated by each RW antenna is reduced, and the exclusivity of the radio waves is increased, so it is possible to accurately detect which RW antenna has read the RFID tag 4.

Figure 19 is a horizontal cross-sectional view (a cross-sectional view seen from above in the vertical direction) showing the antenna surfaces of the first RW antenna 2 and the second RW antenna 3. As shown in Figure 19, the two RW antennas are arranged inside the antenna radome 131 or a resin housing in a V-shape like a roof, and the radiated radio waves of each other are arranged at an angle of about 20 to 45 degrees, assuming that the angle is 0 degrees when they are parallel. This reduces the overlapping area of the radio waves of each other, improving the exclusivity of the radio waves and making it easier to distinguish the read RW antenna. In this embodiment, the bi-fold arrangement when there are two RW antennas has been described, but when there are three RW antennas, a tri-fold arrangement in which the radio waves move away from each other is also possible. Similarly, when the number of RW antennas is increased to four or more, the decrease in the exclusivity of the radio waves can be suppressed by arranging them in an inclined manner so that the radio waves move away from each other.

Example 4 is an example in which the number of RW antennas is limited to one, thereby reducing costs, while ensuring variation in the reading pattern by changing the number of times the RW antenna is read and the time interval.

Figure 20 is a functional block diagram of a foodstuff management system according to Example 4. The foodstuff management system of this example differs from the foodstuff management system of Example 1 shown in Figure 6 in that the RW antenna is the first RW antenna 2 only, and a number detection unit 33 is provided instead of the sequence detection unit 18.

Figure 21A is a front view showing the movement lines 81, 82, and 83 of the first RW antenna 2 and the RFID tag 4. The movement line 81 of the RFID tag 4 indicates the first movement line of the three sliding movement lines (outward movement-outward movement-outward movement) that pass through the first RW antenna 2, and proceeds from the left side to the right side of the first RW antenna 2. The movement line 82 of the RFID tag 4 indicates the second movement line of the three sliding movement lines (outward movement-outward movement-outward movement) that pass through the first RW antenna 2, and proceeds from the left side to the right side of the first RW antenna 2. The movement line 83 of the RFID tag 4 indicates the third movement line of the three sliding movement lines (outward movement-outward movement-outward movement) that pass through the first RW antenna 2, and proceeds from the left side to the right side of the first RW antenna 2.

21B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as in the flow lines 81, 82, and 83 of FIG. 21A, and a graph showing the tag reading timing of the first RW antenna 2. The RFID reader/writer 12 and the control computer 24 determine the timing of reading the RFID tag 4 from the peak of the RSSI waveform of the first RW antenna 2. In FIG. 21B, the first RW antenna 2 corresponding to the first flow line 81 is read for the first time and before the first predetermined time has elapsed. Similarly, the first RW antenna 2 corresponding to the third flow line 83 is read for the third time and before the first predetermined time has elapsed after the first RW antenna 2 corresponding to the second flow line 82 is read for the third time. Therefore, the three slide flow lines are regarded as one input sequence, and the number of reads can be specified as three. Also, as shown in FIG. 21B, the time interval between the first and second slide touches is longer than the time interval between the second and third slide touches. Therefore, if a command table is prepared that corresponds to combinations of long and short time intervals for reading the RFID tag 4 by the RFID reader/writer 12, a certain number of types of commands can be ensured even with a single RW antenna. Furthermore, a command table may be prepared that corresponds to combinations of movement speeds of slide touches of the RFID tag 4.

Figure 22A is a front view showing the movement lines 85, 86, and 87 of the first RW antenna 2 and the RFID tag 4. The movement line 85 of the RFID tag 4 is the first of three sliding movement lines (outward-return-outward) that pass through the first RW antenna 2, and proceeds from the left side to the right side of the first RW antenna 2. The movement line 86 of the RFID tag 4 is the second of three sliding movement lines (outward-return-outward) that pass through the first RW antenna 2, and proceeds from the right side to the left side of the first RW antenna 2. The movement line 87 of the RFID tag 4 is the third of three sliding movement lines (outward-return-outward) that pass through the first RW antenna 2, and proceeds from the left side to the right side of the first RW antenna 2.

22B is a graph showing an RSSI waveform when the RFID tag 4 is slid and touched as in the flow lines 85, 86, and 87 in FIG. 22A, and a graph showing the tag reading timing of the first RW antenna 2. The RFID reader/writer 12 and the control computer 24 determine the timing of reading the RFID tag 4 from the peak of the RSSI waveform of the first RW antenna 2. In FIG. 22B, the first RW antenna 2 is read for the second time corresponding to the flow line 86 before the first predetermined time has elapsed after the first reading of the first RW antenna 2 corresponding to the flow line 85. Similarly, the first RW antenna 2 is read for the third time corresponding to the flow line 87 before the first predetermined time has elapsed after the second reading of the first RW antenna 2 corresponding to the flow line 86. Therefore, the three sliding flow lines are regarded as one input sequence, and the number of readings can be determined to be three.

Example 5 is an example of a configuration having multiple antenna assemblies, each consisting of one or more antennas, which are linked by conductor lines and connected to the RFID reader/writer 12 via a common terminal. In addition, since the number of antennas constituting each antenna assembly is different, it is possible to determine which antenna assembly has been slid and touched based on the number of antennas that have been read. In other words, according to this example, the antenna terminals can be consolidated into one, making it possible to realize a food management system at low cost.

Figure 23 is a diagram showing an antenna configuration according to Example 5. In this example, one conductor line 152 connected to an antenna terminal (not shown) is connected to three branch lines, and multiple antennas are connected to each branch line. Specifically, three RW antennas, RW antenna 134, RW antenna 135, and RW antenna 136, are connected to the first branch line, five RW antennas, RW antenna 137, RW antenna 138, RW antenna 139, RW antenna 140, and RW antenna 141, are connected to the second branch line, and four RW antennas, RW antenna 142, RW antenna 143, RW antenna 144, and RW antenna 145, are connected to the third branch line. That is, the number of RW antennas connected to each branch line is different from each other.

The shape of each RW antenna is elongated in a direction perpendicular to the sliding touch direction of the RFID tag 4, forming a strip shape. Furthermore, the RW antennas are arranged in parallel with each other along their longitudinal direction to form a branch line, and by narrowing the spacing between each RW antenna within the branch line, a large number of RW antennas can be arranged. The spacing between each RW antenna within the branch line is uniform for RW antennas 134-136 and RW antennas 137-141, but is unequal for RW antennas 142-145.

Flow line 150 indicates that RFID tag 4 passes through three RW antennas, 134 to 136; flow line 153 of RFID tag 4 indicates that RFID tag 4 passes through five RW antennas, 137 to 141; flow line 154 indicates that RFID tag 4 passes through four RW antennas, 142 to 145, in the direction from RW antenna 142 to RW antenna 145; and flow line 155 indicates that RFID tag 4 passes through four RW antennas, 142 to 145, in the direction from RW antenna 145 to RW antenna 142. That is, if the RFID tag 4 is read three times in succession, it can be determined that the RW antennas 134 to 136 have been slid and touched, if the RFID tag 4 is read five times in succession, it can be determined that the RW antennas 137 to 141 have been slid and touched, and if the RFID tag 4 is read four times in succession, it can be determined that the RW antennas 142 to 145 have been slid and touched.

In addition, the RW antennas 142 to 145 connected to the third branch line have different antenna installation intervals in the order of large, large, small. Therefore, when the read time intervals of the RFID tag 4 are in the order of long, long, short, it can be determined that the RW antennas 142 to 145 have been slid and touched in the direction of the flow line 154, and when the read time intervals of the RFID tag 4 are in the order of short, long, long, it can be determined that the RW antennas 142 to 145 have been slid and touched in the direction of the flow line 155.
However, the slide touch referred to here means a relatively short distance that allows each movement line to move the RFID tag 4 from the first point to the last point in one go, and does not include operations such as stopping the movement of the RFID tag 4 midway through the movement line or increasing or decreasing the movement speed of the RFID tag 4 from the middle of the movement line. In this way, the reading time interval is not judged as an absolute time, but as a relative length by comparing the previous and next readings, which has the advantage of not being dependent on the movement speed of the RFID tag 4. Therefore, if the number of patterns with regularity in the installation interval of the antenna is increased, the number of commands can be increased accordingly.

The above-mentioned first to fifth embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

1...refrigerator, 2...first RW antenna, 3...second RW antenna, 4...RFID tag, 5...foodstuff, 9...storage compartment door, 11...high frequency processing unit, 12...RFID reader/writer, 13...RSSI detection unit, 14...ID code detection unit, 15...sequence end determination unit, 15a...time interval detection unit, 15b...time interval quantization unit, 16...feature extraction unit, 17...past information storage unit, 18...sequence detection unit, 19...command determination unit, 20...baseband signal processing unit, 21...branching processing unit, 24...control computer, 25...CPU, 26a...first command table storage unit, 26b...second command table storage unit, 28...display device, 30...database processing unit, 31...database server, 33...count detection unit, 72...third RW antenna, 94...fourth RW antenna, 131...antenna radome, 134-145...RW antenna, 151...internet communication network, 152...conductor line

Claims (7)

An antenna that emits radio waves;
A reader that reads an RFID tag attached to an ingredient by a signal received by the antenna;
A food ingredient management system for managing food ingredients stored in a storage facility, comprising:
the antenna has a plurality of antennas capable of communicating with the RFID tag at a near-field distance, and is arranged such that radio waves radiated from each antenna do not overlap at the near-field distance;
The order in which the antennas read the RFID tags determines whether the food materials are being stored in or removed from the storage facility ,
The reader includes:
an order detection unit that detects the order in which the antennas read the RFID tags;
a command table storage unit that stores a command table in which a plurality of commands including the input and output processes of the ingredients are predefined for a plurality of antenna sequences;
an instruction determination unit that refers to the instruction table storage unit and determines an instruction corresponding to the antenna order detected by the order detection unit;
A food management system with In the foodstuff management system according to claim 1 ,
The reader is a food ingredient management system further having a sequence end determination unit that determines that a series of input sequences by a user of the RFID tag has ended if the RFID tag is not read again even after a first predetermined time has elapsed since the RFID tag was last read. In the foodstuff management system according to claim 2 ,
The series of input sequences includes a plurality of input sequences having the same antenna order or a plurality of input sequences having a reverse antenna order. In the foodstuff management system according to claim 2 ,
The sequence end determination unit determines that the input is erroneous if the RFID tag is read again before a second predetermined time has elapsed since the RFID tag was last read. In the foodstuff management system according to claim 1 ,
The reader further includes a time interval detection unit that detects a time interval between reading the RFID tag,
In the instruction table, instructions are predefined for each antenna order and for each variation of time intervals;
The command determination unit determines a command corresponding to the antenna order detected by the order detection unit and the time interval detected by the time interval detection unit. In the foodstuff management system according to claim 1 ,
In the instruction table, instructions are predefined for each antenna order and for each user in the food ingredient management system. In the foodstuff management system according to claim 1,
In the food management system, the multiple antennas are arranged at an angle such that the radio waves radiated from the antennas move away from each other.

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