Temperature information calculation device, temperature information calculation method, quality control method, and quality control system

Abstract

The present invention provides a temperature information calculation device that calculates information relating to time and the temperature of an object by using a time and temperature indicator, the color density of which changes in accordance with a change in temperature and time. A temperature information calculation device (100) according to the present invention comprises: a storage unit (120) that stores in advance, for a plurality of temperatures, a master curve representing the relationship between color density and time at a prescribed temperature indicated by a time and temperature indicator (400); and a calculation unit (130) that calculates information relating to the temperature of the environment in which an object is placed, using information relating to the color density read from the time and temperature indicator (400) applied to the object and the time at which the color density was read, information relating to the color density at a reference point and the time at the reference point, and the master curve stored in the storage unit (120).

Description

Temperature Information Calculation Device, Temperature Information Calculation Method, Quality Management Method, and Quality Management System

[0001] The present invention relates to a temperature information calculation device, a temperature information calculation method, a quality management method, and a quality management system that calculate information related to the temperature of an object, particularly information related to temperature and time.

[0002] Fruits such as melons, mangoes, and peaches that have a post-harvest ripening phenomenon are said to be at their edible stage after a certain period has elapsed since harvest. Also, wine, sake, and meat, etc. have an aging phenomenon, and their taste changes as time passes from production. Further, it is known that the number of days of such aging depends on temperature. Therefore, in order to know the edible or drinkable time of such foods, it is necessary to manage the temperature continuously without interruption during the distribution process of production, transportation, and consumption.

[0003] In order to continuously measure and record the temperature of an object such as food during distribution, a data logger that can continuously record time and temperature is often used.

[0004] Examples of prior art for calculating the edible time of food are described in Patent Document 1 and Patent Document 2.

[0005] Patent Document 1 discloses an edible time management device for enabling consumers to accurately grasp the edible time of processed foods. In the edible time management device disclosed in Patent Document 1, when a consumer reads a code symbol attached to food with a reading device, the data of the code symbol is transmitted to an edible time management server, and the edible time management server obtains the edible time of the food based on the information contained in the code symbol. Even after the food has been handed over to the consumer, the consumer can thus grasp the edible time of the food.

[0006] Patent Document 2 discloses a method for determining the optimal time to eat food by periodically acquiring environmental information, thereby determining the appropriate time for consumption for consumers and store staff. In the method for determining the optimal time to eat food disclosed in Patent Document 2, a contactless tag equipped with a sensor, antenna, and memory is attached to each individual food item, environmental information is periodically acquired from the sensor and stored in the memory, the contents of the memory are read from detection devices installed at multiple points along the distribution route and stored in a server, and the optimal time to eat food for each individual food item is calculated based on future distribution route information and past environmental information.

[0007] Japanese Patent Publication No. 2020-57279 Japanese Patent Publication No. 2005-280909

[0008] The food-readiness management device described in Patent Document 1 calculates the optimal eating time of food by considering only the ambient temperature of the manufacturing plant at the time of food production as temperature information. In contrast, the food-readiness detection method described in Patent Document 2 can calculate the optimal eating time of food by considering the temperature information until the food reaches the consumer. However, in order to calculate the optimal eating time of each individual food item, it is necessary to attach a contactless tag equipped with a sensor, antenna, and memory to all food items, which increases costs. Furthermore, it is necessary to obtain the correlation between detailed temperature information and the optimal eating time in advance.

[0009] In last-mile logistics and similar applications, the need to manage each item individually makes the use of data loggers difficult due to cost and size considerations. Furthermore, determining the optimal time for consumption (e.g., eating or drinking) requires information on the temperature and number of days since the item reached the consumer. Therefore, it is necessary to acquire information on the temperature and number of days (i.e., time) of each item and use this information to obtain an indicator of the optimal time for consumption using a simple method.

[0010] The objective of the present invention is to provide a temperature information calculation device, a temperature information calculation method, a quality control method, and a quality control system that calculate information about the temperature and time of an object using a time-temperature indicator whose color density changes in accordance with changes in temperature and time, in order to realize a quality control system in which information about the quality of an object can be consistently obtained from shipment to consumption.

[0011] The temperature information calculation device according to the present invention comprises a storage unit that pre-stores master curves representing the relationship between color density and time at predetermined temperatures indicated by a time-temperature indicator for a plurality of temperatures, and a calculation unit that calculates information regarding the temperature of the environment in which the object is placed using information regarding the color density read from a time-temperature indicator attached to the object and the time read, information regarding the color density at a reference point and the time at that reference point, and the master curve stored in the storage unit.

[0012] Furthermore, the quality control system according to the present invention uses the color of the ink portion of the cumulative temperature indicator, a master curve showing the relationship between the number of days at a predetermined temperature and the color density of the ink portion, and the relationship between the quality of the object and its color density to calculate and present to the user the date by which the product will reach its desired quality, such as the appropriate storage temperature and optimal eating time.

[0013] According to the present invention, it becomes possible to implement a low-cost and simple quality control system that allows for consistent access to information regarding the quality of an object from shipment to consumption. In particular, it becomes possible to consistently provide a new consumer experience that includes quality traceability and prediction of when the product is ready to eat.

[0014] This figure shows an example of the configuration of a temperature information calculation device according to an embodiment of the present invention. This flowchart shows an example of the processing of the temperature information calculation method according to this embodiment. This figure shows an example of a master curve. This figure shows an example of a time-temperature indicator. This figure shows the master curve for 25°C among the master curves for multiple temperatures stored in the color information storage unit. This figure shows the master curves for 25°C and 15°C among the master curves for multiple temperatures stored in the color information storage unit. This figure shows an example of the screen displayed by the output unit. This figure shows an example of another configuration of the temperature information calculation device according to this embodiment. This figure shows an example of the configuration of a server connected to the temperature information calculation device according to this embodiment. This figure shows an example of unique ID information provided on the same printed material as the time-temperature indicator.

[0015] The temperature information calculation device, temperature information calculation method, quality control method, and quality control system according to the present invention use a time-temperature indicator whose color density changes in accordance with changes in temperature and time, and calculate information regarding the temperature and time of an object based on the color density indicated by the time-temperature indicator. The time-temperature indicator has thermochromic ink printed on its surface, and the color of this thermochromic ink changes in accordance with changes in temperature and time. Information regarding the temperature and time of an object includes, for example, the temperature of the environment in which the object is placed, the time the object was placed at this temperature, and the quality of the object.

[0016] Compared to contactless tags equipped with sensors, antennas, and memory, temperature indicators can manage the temperature information of individual objects at a lower cost. Although temperature indicators do not have the same recording accuracy as data loggers, many are inexpensive and can be attached to individual objects. In typical types of temperature indicators, the surface is stained when the temperature exceeds or falls below a preset temperature. This type of temperature indicator makes it possible to know whether an object has been exposed to an abnormal temperature. Since time information (e.g., number of days) is important in addition to temperature information for determining when food is ready to eat or drink, a time-temperature indicator (TTI) in which the color intensity changes with the accumulation of temperature and time is desirable. In the time-temperature indicator in this embodiment, the discoloration rate increases exponentially with increasing temperature, so it is possible to establish a correlation between the time and temperature at which the time-temperature indicator discolors and the time and temperature at which the quality or maturity of food changes.

[0017] When applying a time-temperature indicator to changes in the quality of an object (e.g., the quality, maturity, or freshness of food), it is necessary to establish a correlation between the time and temperature at which the time-temperature indicator changes color and the time and temperature at which the quality of the object changes. When evaluating changes in the quality of an object, reaction kinetic analysis, such as the Arrhenius rule, is widely used. According to this, the rate of change in quality increases exponentially with increasing temperature. In a time-temperature indicator that becomes colored due to crystallization, the crystallization rate increases exponentially with increasing temperature within a certain temperature range. That is, in a time-temperature indicator, the rate of color change increases exponentially with increasing temperature. Therefore, it is possible to establish agreement or correlation between the time and temperature at which the time-temperature indicator changes color and the time and temperature at which the quality of the object changes.

[0018] The following describes in detail, with reference to the drawings, a temperature information calculation device, a temperature information calculation method, a quality control method, and a quality control system according to embodiments of the present invention. In the following embodiments, as an example, an example will be described in which the object for which temperature information is calculated is food, and the quality of the object is the optimal time for eating (including the optimal time for drinking) the food. However, the present invention is not limited to food, and the object can be any article whose quality changes according to an Arrhenius-type temperature dependence. Articles whose quality changes according to an Arrhenius-type temperature dependence include, in addition to food, pharmaceuticals, chemical products, agricultural products, cut flowers, plastics, metal parts, and batteries.

[0019] The quality of an object can be arbitrarily determined depending on the object. For example, the quality of food is its ripeness, maturity, and freshness; the quality of pharmaceuticals is their effectiveness; the quality of chemical products is their strength; the quality of agricultural crops is their growth stage; the quality of cut flowers is their transport quality; the quality of plastic and metal parts is their state of deterioration; and the quality of batteries is their lifespan.

[0020] In the drawings referenced herein, identical or corresponding components are denoted by the same reference numeral, and repeated descriptions of these components may be omitted.

[0021] Figure 1 shows an example of the configuration of a temperature information calculation device 100 according to an embodiment of the present invention. The temperature information calculation device 100 comprises a color information acquisition unit 110, a color information storage unit 120, a temperature information calculation unit 130, a unique ID information acquisition unit 140, a quality information storage unit 150, an input unit 160, and an output unit 170. The temperature information calculation device 100 can be configured as a portable information terminal with a camera function, such as a smartphone or tablet terminal. Furthermore, as will be described later, the temperature information calculation device 100 may also include a database 180 and may include AI 190 (artificial intelligence).

[0022] The temperature information calculation device 100 can connect to a communication network such as the Internet, and can connect to the server 200 via the communication network. The temperature information calculation device 100 can communicate with the server 200 and send and receive information to each other.

[0023] The temperature information calculation unit 130 may be provided not in the temperature information calculation device 100, but in a server 200 connected to the temperature information calculation device 100. Furthermore, the temperature information calculation device 100 may comprise only the color information acquisition unit 110, the unique ID information acquisition unit 140, the input unit 160, and the output unit 170 from the above-mentioned components.

[0024] Figure 8A shows an example of another configuration of the temperature information calculation device 100 according to this embodiment. The temperature information calculation device 100 includes a color information acquisition unit 110, a unique ID information acquisition unit 140, an input unit 160, and an output unit 170.

[0025] Figure 8B shows an example of the configuration of a server 200 connected to the temperature information calculation device 100 according to this embodiment.

[0026] If the temperature information calculation device 100 has the configuration shown in Figure 8A, the server 200 includes a color information storage unit 120, a temperature information calculation unit 130, a quality information storage unit 150, a database 180, and an AI 190.

[0027] The temperature information calculation device 100 according to this embodiment can perform the temperature information calculation method according to this embodiment.

[0028] A time-temperature indicator is attached to an object from which information about temperature and time is to be obtained. A time-temperature indicator changes color based on the cumulative effect of temperature and time; for example, it may be a seal, label, or card with thermochromic ink printed or coated on it. Alternatively, a time-temperature indicator may indicate temperature changes through the penetration of a liquid. Hereinafter, seals, labels, and cards with thermochromic ink printed or coated on them will be referred to as printed materials.

[0029] The time-temperature indicator may be attached directly to the object or attached adjacent to it. For example, the time-temperature indicator may be affixed to the object, or a printed version may be placed adjacent to the object. Alternatively, the time-temperature indicator may be directly printed, inscribed, coated, or transferred onto the object.

[0030] The color information acquisition unit 110 acquires the color density indicated by a time-temperature indicator, whose color density changes in accordance with changes in temperature and time. The color information acquisition unit 110 may be equipped with optical devices that can acquire and store optical information, such as a camera, an optical sensor, and a colorimeter. The color information acquisition unit 110 acquires the color density indicated by the time-temperature indicator by, for example, taking an image of the time-temperature indicator and reading the time-temperature indicator.

[0031] The color information storage unit 120 pre-stores the relationship between color density and time, as indicated by the time-temperature indicator, for multiple temperatures. This relationship between color density and time can be obtained through experiments conducted in advance. Hereinafter, the curve representing the relationship between color density and time, as indicated by the time-temperature indicator, will be referred to as the master curve. Since the master curve differs depending on the type of thermochromic ink, the color information storage unit 120 pre-stores master curves for multiple types of thermochromic ink. That is, the color information storage unit 120 pre-stores master curves for multiple temperatures for each of the multiple types of thermochromic ink. The master curve for a certain thermochromic ink at a predetermined temperature T may be stored as the formula V = f(t) or as a datasheet (t, V). Here, V represents color density and t represents time.

[0032] The temperature information calculation unit 130 calculates information about the temperature and time of an object based on the master curve (the relationship between the color density shown by the time-temperature indicator and time for multiple temperatures) stored in the color information storage unit 120 and the color density shown by the time-temperature indicator acquired by the color information acquisition unit 110. The information about the temperature and time of an object includes information about the quality of the object, such as the average temperature of the environment in which the object is placed and the optimal time for eating the food object.

[0033] The unique ID information acquisition unit 140 acquires the unique ID information of the object. The unique ID information includes a unique value that identifies the object. The unique ID information may further include the variety and label type. The variety is information indicating the type of object. The label type is information indicating the type of thermochromic ink of the time-temperature indicator. The time change of the color density of the time-temperature indicator, i.e., the master curve, differs depending on the type of thermochromic ink.

[0034] The unique ID information of an object is recorded in the form of a code or string, such as a two-dimensional code, and printed on a sticker, label, or card. The unique ID information may be attached directly to the object or attached adjacent to the object. For example, the unique ID information may be provided on the same printed material as the time-temperature indicator, as shown in Figure 9, or it may be attached to the object separately from the time-temperature indicator, although this is not shown in the illustration.

[0035] Figure 9 shows an example of unique ID information provided on the same printed material as the time-temperature indicator.

[0036] The unique ID information acquisition unit 140 acquires the unique ID information of an object by reading the object's code or string. The unique ID information acquisition unit 140 can be configured with the same optical device as the color information acquisition unit 110. Note that the device for reading the object's code or string and the device for reading the time and temperature indicator may be the same optical device.

[0037] Of the unique ID information, the variety and label type do not necessarily need to be acquired by the unique ID information acquisition unit 140, and may be stored in either or both the temperature information calculation device 100 and the server 200. For example, if the temperature information calculation device 100 is used as a temperature indicator for a specific object or for a specific time, the variety and label type can be used by referring to data stored in the temperature information calculation device 100 or the server 200, even if they are not acquired by the unique ID information acquisition unit 140. For example, the temperature information calculation unit 130 can calculate information about the temperature and time of an object using a master curve for thermochromic ink obtained from the label type stored in the server 200.

[0038] The quality information storage unit 150 stores in advance the relationship between the quality of the object and the color density of the time-temperature indicator. The quality of the object can be represented by the color density of the time-temperature indicator. For example, the quality information storage unit 150 stores a relationship in which the quality of the object is in a specific state when the color density of the time-temperature indicator is within a specific range. For example, if the quality of the object is that of food that is ready to eat, the quality information storage unit 150 stores a relationship in which the food is ready to eat when the color density V is between Va and Vb.

[0039] Furthermore, the quality of an object can be divided into multiple levels according to the degree of quality. For example, if the quality of an object is the optimal eating time for food, and the degree of quality is the softness of the food, then the optimal eating time can be divided into multiple levels according to the softness of the food (for example, the higher the level, the softer the food). This allows the optimal eating time to be tailored to consumer preferences. The quality information storage unit 150 can also store relationships such as, for example, that when the color density V is V1 or greater and less than V2, the optimal eating time for the food is level 1, and when the color density V is V2 or greater and less than V3, the optimal eating time for the food is level 2.

[0040] The temperature information calculation unit 130 can obtain the relationship between the quality of the object and the color density of the time-temperature indicator from the quality information storage unit 150.

[0041] The input unit 160 is a component for a user of the temperature information calculation device 100 to input information into the temperature information calculation device 100.

[0042] The output unit 170 includes a screen and displays the calculation results of the temperature information calculation device 100 and the information input by the input unit 160 on the screen. For example, the output unit 170 displays the average temperature of the environment where the object is placed and the quality of the object (e.g., the right time to eat the food) calculated by the temperature information calculation unit 130. Further, the output unit 170 displays a message regarding the quality of the object. Examples of messages regarding the quality of the object are a message indicating that the quality is within a predetermined quality range and a message indicating that the quality has gone out of the predetermined quality range.

[0043] FIG. 2 is a flowchart showing an example of the processing of the temperature information calculation method according to an embodiment of the present invention. The temperature information calculation method according to the present embodiment is executed by the temperature information calculation device 100 according to the present embodiment.

[0044] In S201, the color information acquisition unit 110 reads the time-temperature indicator of the object, and the unique ID information acquisition unit 140 reads the code or character string of the object.

[0045] In S202, the color information acquisition unit 110 acquires the color density indicated by the time-temperature indicator, and the unique ID information acquisition unit 140 acquires the unique ID information of the object. Further, the color information acquisition unit 110 acquires the date and time (reading date and time) when the time-temperature indicator was read.

[0046] In S203, based on the color density of the time-temperature indicator acquired by the color information acquisition unit 110 and the master curve stored in the color information storage unit 120, the temperature information calculation unit 130 calculates information regarding the temperature and time of the object (including information regarding the quality of the object), for example, the average temperature of the environment where the food is placed and the right time to eat the food. Further, the temperature information calculation unit 130 can calculate the integrated temperature of the environment where the food is placed.

[0047] In S204, the output unit 170 displays information regarding the temperature and time of the object calculated by the temperature information calculation unit 130, for example, the average temperature of the environment where the food is placed and the time when the food is ready to be eaten. Further, the output unit 170 can display the integrated temperature of the environment where the food is placed calculated by the temperature information calculation unit 130. Furthermore, the output unit 170 can display a message regarding the quality of the object (for example, a message indicating that the quality is within a predetermined quality range or a message indicating that the quality has deviated from the predetermined quality range). The items displayed by the output unit 170 in S204 will also be described in the following explanation.

[0048] FIG. 3 is a diagram showing an example of a master curve. The color information storage unit 120 stores, as a master curve, a curve representing the relationship between the color density indicated by the time-temperature indicator and time for a plurality of temperatures. FIG. 3 shows, as an example, curves representing the relationship between the color density indicated by the time-temperature indicator and time for three temperatures of 5°C, 15°C, and 25°C. Note that the time on the horizontal axis indicates the number of days elapsed from an arbitrarily determined reference time.

[0049] The color density indicated by the time-temperature indicator changes with time (number of days) for each of the plurality of temperatures. As shown in FIG. 3, the higher the temperature, the faster the change in color density. That is, the time-temperature indicator has a characteristic that the rate of change of color density increases as the temperature rises within a certain temperature range according to the time-temperature indicator (at least the temperature range from 5°C to 25°C). Also, as shown in FIG. 3, the color density increases monotonically with the passage of days. That is, the time-temperature indicator has a characteristic that the color density increases monotonically with time change within a certain time range according to the time-temperature indicator.

[0050] FIG. 4 is a diagram showing an example of the time-temperature indicator 400. In this embodiment, the time-temperature indicator 400 includes an ink portion 401, a reference color portion 402, and a reference color portion 403.

[0051] The ink section 401 is the part on which thermochromic ink is printed. The color information acquisition unit 110 determines the color density of the time temperature indicator based on the color of the ink section 401. The color of the ink section 401 read by the color information acquisition unit 110 is called the read color. The color information acquisition unit 110 acquires the RGB values ​​(r', g', b') of the read color.

[0052] The reference color section 402 is the section on which the reference color is printed, which is used by the color information acquisition unit 110 to determine the color density of the time temperature indicator. The color of the reference color section 402 read by the color information acquisition unit 110 is called the reference color. The color density of the reference color does not change. The color information acquisition unit 110 acquires the RGB values ​​(R1, G1, B1) of the reference color.

[0053] The reference color section 403 is the section on which the color used by the color information acquisition unit 110 when correcting the read color and the reference color is printed. The color of the reference color section 403 read by the color information acquisition unit 110 is called the reference color. The reference color is a different color from the reference color, and its color density does not change. The color information acquisition unit 110 acquires the RGB values ​​(R0, G0, B0) of the reference color.

[0054] The color information acquisition unit 110 reads the read color, the reference color, and the reference color, and corrects the read color and the reference color using the reference color. In this embodiment, the color information acquisition unit 110 corrects the read color and the reference color according to the following formulas: Corrected read color (r, g, b) = (r' - R0, g' - G0, b' - B0) Corrected reference color (R, G, B) = (R1 - R0, G1 - G0, B1 - B0) The color information acquisition unit 110 calculates the color density of the time temperature indicator using the corrected read color and the corrected reference color. In this embodiment, the color information acquisition unit 110 calculates the color density according to the following formula: Color density V0 = (r * R + g * G + b * B) / (R^2 + G^2 + B^2) In this manner, the color information acquisition unit 110 reads the time temperature indicator of the object and obtains the color density V0 indicated by the time temperature indicator.

[0055] The temperature information calculation unit 130 calculates information about the temperature and time of an object, such as the average temperature of the environment in which the food is placed and the ideal time to eat the food, from the color density V0 of the time-temperature indicator acquired by the color information acquisition unit 110 and the master curve (for example, Figure 3) stored in the color information storage unit 120.

[0056] Here, an example of how the temperature information calculation unit 130 calculates the optimal eating time for food from the color density V0 of the time-temperature indicator and the master curve will be explained with reference to Figure 5. The temperature information calculation unit 130 calculates information about the optimal eating time for food using the relationship between the optimal eating time for food and the color density of the time-temperature indicator, which is stored in the quality information storage unit 150.

[0057] Figure 5 shows the master curve for 25°C, which is one of several master curves for temperature stored in the color information storage unit 120 (for example, Figure 3). 25°C was selected as an example of a food storage temperature; any master curve related to the storage temperature of the object can be appropriately selected.

[0058] First, the temperature information calculation unit 130 obtains from the quality information storage unit 150 the range of color density V when the food is ready to eat (for example, Va or more and less than Vb). In this example, when the color density V reaches Va, the food is considered ready to eat. The range of color density V when the food is ready to eat can be arbitrarily determined in advance.

[0059] Next, the temperature information calculation unit 130 refers to a 25°C master curve (Figure 5) and determines the number of days T0 corresponding to the color density V0 of the time temperature indicator acquired by the color information acquisition unit 110, and the number of days Ta corresponding to the color density Va of the optimal eating temperature.

[0060] The temperature information calculation unit 130 then determines the number of days T25 until the food reaches its optimal eating state, using the formula T25 = Ta - T0.

[0061] In this way, the temperature information calculation unit 130 can calculate the ideal eating time (number of days T25 until the food reaches its ideal eating time) when the ambient temperature of the food is 25°C. If the ideal eating time is divided into multiple levels, the temperature information calculation unit 130 can calculate the number of days until the food reaches the color density of each level (for example, color density V1 for level 1, and color density V2 for level 2) as the ideal eating time.

[0062] The temperature information calculation unit 130 calculates the ideal serving time for each of the multiple temperatures stored in the master curve (for example, three temperatures of 5°C, 15°C, and 25°C).

[0063] The temperature information calculation unit 130 can calculate the ideal eating time for food (the number of days until it reaches its ideal eating time) according to the temperature of the environment in which the food is placed, as described above.

[0064] Here, an example of how the temperature information calculation unit 130 calculates the average temperature of the environment in which the food is placed from the color density V0 of the time temperature indicator and the master curve will be explained with reference to Figure 6. The average temperature is the average temperature of two different points in time.

[0065] Let's assume that at the first of these two time points, the color density of the time temperature indicator is V01, and at the second time point, the color density of the time temperature indicator is V02. Let's assume that the color information acquisition unit 110 acquires the color density V01 at the first time point and the color density V02 at the second time point.

[0066] In the following example, for the sake of simplicity, we will use two master curves, one for 25°C and the other for 15°C, to explain how to calculate the average temperature of the environment in which food is placed.

[0067] Figure 6 shows the master curves for 25°C and 15°C, which are among the master curves for multiple temperatures stored in the color information storage unit 120.

[0068] First, the temperature information calculation unit 130 obtains the number of days corresponding to the color density V01 of the time temperature indicator at each temperature from the master curves for multiple temperatures stored in the color information storage unit 120. In this embodiment, for a temperature of 25°C, the temperature information calculation unit 130 refers to the master curve for 25°C and obtains the number of days T1 corresponding to the color density V01, and for a temperature of 15°C, it refers to the master curve for 15°C and obtains the number of days T1' corresponding to the color density V01.

[0069] Next, the temperature information calculation unit 130 calculates the number of days ΔT elapsed from a first time point in time when the color density of the time temperature indicator is V01 to a second time point in time when the color density of the time temperature indicator is V02. The temperature information calculation unit 130 calculates the number of days ΔT elapsed from the reading date and time of color density V01 (first time point) and the reading date and time of color density V02 (second time point) acquired by the color information acquisition unit 110.

[0070] Next, the temperature information calculation unit 130 determines the color density V at a time when ΔT days have elapsed from the number of days corresponding to the color density V01, using the master curve for each temperature. In this embodiment, for a temperature of 25°C, the temperature information calculation unit 130 refers to the master curve for 25°C and determines the color density V2 at time T2 (= T1 + ΔT), which is ΔT days after the number of days T1 corresponding to the color density V01. For a temperature of 15°C, the temperature information calculation unit 130 refers to the master curve for 15°C and determines the color density V2' at time T2' (= T1' + ΔT), which is ΔT days after the number of days T1' corresponding to the color density V01.

[0071] Next, the temperature information calculation unit 130 determines whether the color density V02 of the time temperature indicator at the second time point is closer to color density V2 or color density V2'. Then, the temperature information calculation unit 130 sets the temperature of the master curve representing the color density closer to color density V02 as the average temperature of the environment in which the food is placed (the average temperature of the first and second time points).

[0072] In the example shown in Figure 6, since the color density V02 is close to the color density V2 obtained from the 25°C master curve, the temperature information calculation unit 130 uses the temperature (25°C) of the master curve (25°C master curve) that represents the color density V2 which is close to the color density V02 as the average temperature of the environment in which the food is placed (the average temperature of the first and second time points). In other words, the temperature information calculation unit 130 calculates the average temperature of the environment in which the food is placed as 25°C.

[0073] Furthermore, if there are multiple master curves that represent color densities close to color density V02, the temperature information calculation unit 130 may determine the range of temperatures taken by these master curves as the average temperature range.

[0074] Alternatively, the average temperature T02 can be calculated from the values ​​of two master curves that represent color densities close to the color density V02 using the following formula. Here, the temperatures of the master curves that represent close color densities are α and β (α > β), and the color density of master curve α at the second time point is defined as Vα, the color density of master curve β as Vβ, and the temperatures as Tα and Tβ. T02 = (V02 - Vβ)(Tα - Tβ) / (Vα - Vβ) + Tβ When α = 25℃ and β = 15℃, T02 = (V02 - V15)(T25 - T15) / (V25 - V15) + T15.

[0075] As described above, the temperature information calculation unit 130 can calculate the average temperature of the environment in which the food is placed from the color densities V01 and V02 of the time temperature indicator acquired by the color information acquisition unit 110 and the master curves for multiple temperatures stored in the color information storage unit 120. In other words, the temperature information calculation unit 130 uses the color densities at two points in time obtained by reading the time temperature indicator and the master curves for multiple temperatures to find the master curve that shows the change in color density closest to the change in color density at the two points in time, and calculates the temperature of the found master curve as the average temperature of the environment in which the food is placed.

[0076] In the above explanation, an example was described in which the color information acquisition unit 110 acquires the color density V01 at a first time point and the color density V02 at a second time point from the time-temperature indicator, and the temperature information calculation unit 130 uses these color densities V01 and V02 to calculate the average temperature of the environment in which the food is placed.

[0077] The color information acquisition unit 110 may not acquire the color density V01 at the first time point, but only the color density V02 at the second time point. In this case, the temperature information calculation unit 130 may use a value previously stored in the temperature information calculation unit 130 as the color density V01 at the first time point. For example, the temperature information calculation unit 130 may define the day the food was harvested (the day with zero days) as the first time point, and store the color density V01 at this first time point as a predetermined initial value. In this case, the color information acquisition unit 110 only needs to acquire the color density once.

[0078] The temperature information calculation unit 130 can calculate the cumulative temperature of the environment in which the food is placed. This cumulative temperature is the cumulative temperature between two points in time when the average temperature was calculated. The temperature information calculation unit 130 calculates the cumulative temperature by multiplying the calculated average temperature by the number of days elapsed ΔT. The temperature information calculation unit 130 can display the calculated cumulative temperature on the output unit 170.

[0079] The output unit 170 displays the optimal eating time for the food, as well as the average and cumulative temperatures of the environment in which the food is placed, based on a command from the temperature information calculation unit 130.

[0080] The temperature information calculation unit 130 may also calculate a temperature related to the average temperature, either in place of the average temperature or together with the average temperature. Temperatures related to the average temperature include, for example, the temperature obtained by multiplying the average temperature by a first constant, the temperature obtained by adding a second constant to the average temperature, and the temperature obtained by adding a second constant to the temperature obtained by multiplying the average temperature by the first constant. The first and second constants can be arbitrarily determined in advance.

[0081] Furthermore, the temperature information calculation unit 130 may calculate a temperature related to the accumulated temperature, either in place of or along with the accumulated temperature. Temperatures related to the accumulated temperature include, for example, the temperature obtained by multiplying the accumulated temperature by a third constant, the temperature obtained by adding a fourth constant to the accumulated temperature, and the temperature obtained by adding the fourth constant to the temperature obtained by multiplying the accumulated temperature by the third constant. The third and fourth constants can be arbitrarily determined in advance. In addition to the constants, values ​​related to the average temperature may also be multiplied or added.

[0082] In this embodiment, the cumulative temperature indicator is read for each event in logistics, such as storage and transportation (sea freight, land freight, last mile delivery, etc.), linked to a unique ID, and recorded. The temperature information calculation unit 130 then calculates the average temperature and / or cumulative temperature, making it possible to trace the status of logistics.

[0083] The temperature information calculation unit 130 can calculate information regarding the temperature and time of an object, such as the average temperature of the environment in which the food is placed and the ideal eating time of the food, using the unique ID information of the object acquired by the unique ID information acquisition unit 140. If the unique ID information includes a label type that indicates the type of thermochromic ink of the time-temperature indicator, the temperature information calculation unit 130 identifies the type of thermochromic ink of the time-temperature indicator from the unique ID information and uses the master curve for the identified thermochromic ink. As described above, the master curve differs depending on the type of thermochromic ink, so by using the master curve for the identified thermochromic ink, the temperature information calculation unit 130 can calculate the average temperature and ideal eating time more accurately.

[0084] The temperature information calculation unit 130 can display on the output unit 170 that the food is ready to eat if the color density V0 obtained by the color information acquisition unit 110 reading the time temperature indicator falls within the range of color density V that indicates the food is ready to eat. Conversely, if the color density V0 falls outside the range of color density V that indicates the food is ready to eat, the temperature information calculation unit 130 can display on the output unit 170 that the food is past its prime.

[0085] The output unit 170 displays a message indicating that the food is ready to eat or that the food is past its prime, based on a command from the temperature information calculation unit 130. In this way, the output unit 170 also displays a message indicating that the quality of the object is within a predetermined quality range or that the quality of the object has fallen outside a predetermined quality range.

[0086] Furthermore, the temperature information calculation unit 130 can display on the output unit 170 the number of days until the food reaches its optimal eating temperature for each of the multiple temperatures calculated for the master curve. In addition, the temperature information calculation unit 130 can display on the output unit 170 the number of days that have elapsed since the food reached its optimal eating temperature for each of these multiple temperatures.

[0087] The output unit 170, based on a command from the temperature information calculation unit 130, displays the number of days until the food reaches its optimal eating temperature for multiple temperatures, and the number of days that have elapsed since the food reached its optimal eating temperature. In this way, the output unit 170 displays the number of days until the quality of the object reaches a predetermined quality range, and the number of days that have elapsed since the quality of the object entered a predetermined quality range.

[0088] Users of the temperature information calculation device 100 can specify the quality level of the object using the input unit 160. For example, a user can specify that soft food is ready to eat.

[0089] The temperature information calculation unit 130 can calculate information about the quality of an object using information about the quality of the object entered by the user using the input unit 160. For example, the temperature information calculation unit 130 can receive the quality level entered by the user from the input unit 160 and change a predetermined quality range to correspond to the received quality level. For example, if the user specifies that a soft food is ready to eat, the range of color density V used to calculate the ready-to-eat state is changed to a range of color density that indicates the food is soft.

[0090] The quality information storage unit 150 can store relationships such as: if the color density V is V1 or greater and less than V2, the food is ready to eat at level 1; if the color density V is V2 or greater and less than V3, the food is ready to eat at level 2; and food at level 2 is softer than food at level 1. For example, if the user specifies that soft food is ready to eat, the temperature information calculation unit 130 changes the range of color density V used to calculate the ready-to-eat state from, for example, level 1, where the color density V is V1 or greater and less than V2, to level 2, where the color density V is V2 or greater and less than V3.

[0091] The temperature information calculation device 100 may, when a user specifies a certain quality level for an object, display the type of object corresponding to that specified quality level and the ideal time for consumption of that object. For example, if a user specifies that a soft food is ready to eat, the temperature information calculation device 100 may display a soft type of food and its ideal time for consumption on the output unit 170.

[0092] For example, the temperature information calculation device 100 may include a database 180 (Figure 1) that stores information on food varieties and their approximate eating times. The temperature information calculation unit 130 refers to this database 180 to determine the variety that is suitable for the eating time specified by the user (for example, a soft variety) and its eating time. The output unit 170 then displays the variety and eating time determined by the temperature information calculation unit 130.

[0093] Furthermore, the temperature information calculation device 100 is equipped with an AI 190 (Figure 1), and the AI ​​190 may be used to determine the variety of food that corresponds to the ideal eating time specified by the user, and the ideal eating time for that food. The AI ​​190 learns food varieties and their approximate eating times from data previously entered by one or more users. The temperature information calculation unit 130 uses the data learned by the AI ​​190 to determine the variety that matches the ideal eating time specified by the user, and the ideal eating time for that variety. The output unit 170 then displays the variety and ideal eating time determined by the temperature information calculation unit 130.

[0094] Figure 7 shows an example of the screen 171 displayed by the output unit 170.

[0095] The output unit 170 displays, for example, the average temperature and cumulative temperature of the environment in which the food is placed, and the optimal time to eat the food (number of days until it reaches optimal eating) according to the temperature of the environment in which the food is placed, on the screen 171. Figure 7 shows an example in which the range of the average temperature of the environment in which the food is placed is displayed, and the time until the food reaches optimal eating is displayed.

[0096] Furthermore, the output unit 170 can display on the screen 171 the degree to which a food is ready to eat, as specified by the user of the temperature information calculation device 100 using the input unit 160. Figure 7 shows an example where "slightly soft" is specified as the degree to which a food (melon) is ready to eat.

[0097] As explained above, the temperature information calculation method, temperature information calculation device, and system in this embodiment store master curves for multiple temperatures of an integrated temperature indicator. The master curves show a monotonically increasing correlation between the number of days and color density at a predetermined temperature. The system searches for a master curve that is close to the change in color density from the color density of the integrated temperature indicator, the color density at a reference point, and the number of days (hours) elapsed since the reference point. Using this master curve, the system calculates the average temperature, and then uses the elapsed days and the average temperature to determine the integrated temperature. In other words, the temperature information calculation method, temperature information calculation device, and system in this embodiment pre-determine master curves showing the relationship between color density and time at a predetermined temperature for multiple temperatures, and obtain information about the temperature of the environment in which the object is placed by utilizing the difference between the elapsed time and the color of the ink. According to this embodiment, by using a master curve that is close to the change in color density of the integrated temperature indicator, it is possible to accurately calculate the average temperature and integrated temperature of an object by reading the integrated temperature indicator with a terminal such as a smartphone. This makes it possible to trace information related to the quality of an object in a low-cost, lightweight, and simple manner.

[0098] The reference point here can be pre-set information such as the time of shipment, or it can be the time when the cumulative temperature indicator was previously read. To link the reference point information with the measured information, it is preferable to record the information read from the cumulative temperature indicator (color density, date) and a unique ID. By executing the temperature information calculation method in this embodiment at the start and end of each logistics event, it becomes possible to trace the storage status of each event.

[0099] Furthermore, it is preferable to use the product information of the object, the color of the ink portion of the cumulative temperature indicator, and the master curve to calculate and present to the user the date on which the product will reach its desired quality, such as the appropriate storage temperature and when it is ready to eat. In this embodiment, the relationship between the quality of the object and its color density is determined in advance, and by comparing it with the master curve corresponding to the appropriate storage temperature of the object, the number of days required for the object to reach its desired quality color density is calculated. Since users can obtain information about the quality of the object, such as when it is ready to eat, as well as the appropriate storage temperature and storage days, simply by reading the time-temperature indicator, this embodiment makes it possible to provide an even newer consumer experience.

[0100] Regarding the product information of the object, it may be read from the unique ID assigned to the object, or the product information may be pre-linked to a terminal or app that reads the cumulative temperature indicator, or the user may input or select it, or the information may be stored on the server side. Furthermore, regarding the quality of the object, such as the ideal eating time, which is presented to the user, the AI ​​may learn the user's preferred quality and change the quality setting value for each user.

[0101] Furthermore, as shown in Figure 8, a color information acquisition unit 110 and a unique ID information acquisition unit 140 may be configured on the terminal side (edge ​​side) such as a smartphone, and a color information storage unit 120, temperature information calculation unit 130, quality information storage unit 150, database 180, and AI 190 may be configured on the server 200 side. In other words, the color information and unique information acquired on the terminal side may be sent to the server side (including the cloud), and the average temperature and integrated temperature may be calculated on the server side using the master curve stored on the server side. The color density information sent from the terminal side to the server side may be the acquired camera image itself, or it may be the color density calculated on the terminal side. In the former case, image data can be stored, which has the advantage of reliability of traceability and can be used for later data analysis, while in the latter case, it has the advantage of reducing data communication charges. The server sends average temperature and integrated temperature information to the terminal side, and the terminal side presents the necessary information to the user based on the received information.

[0102] The present invention may also have the following features.

[0103] (1) A temperature information calculation method characterized by being executed on a temperature information calculation device comprising a color information acquisition unit, a color information storage unit, and a temperature information calculation unit, wherein a time-temperature indicator, on which thermochromic ink is printed and whose color density changes according to changes in temperature and time, is attached to the object, the color information storage unit has in advance stored a master curve, which is a curve representing the relationship between the color density shown by the time-temperature indicator and time, for a plurality of temperatures, and comprising: a color density acquisition step in which the color information acquisition unit acquires the color density shown by the time-temperature indicator; and a calculation step in which the temperature information calculation unit calculates information about the temperature of the environment in which the object is placed and information about the quality of the object, based on the color density acquired by the color information acquisition unit and the master curve stored in the color information storage unit.

[0104] (2) The temperature information calculation method according to (1), wherein the temperature information calculation device comprises a unique ID information acquisition unit, the unique ID information includes information that identifies the object and a label type which is information about the thermochromic ink, the unique ID information acquisition unit has a unique ID acquisition step of acquiring the unique ID information of the object, and in the calculation step, the temperature information calculation unit uses the master curve for the thermochromic ink obtained from the unique ID information acquired by the unique ID information acquisition unit.

[0105] (3) The temperature information calculation device comprises a quality information storage unit, the quality information storage unit stores in advance the relationship between the quality of the object and the color density, and in the calculation step, the temperature information calculation unit calculates information about the quality of the object using the relationship between the quality of the object and the color density stored in the quality information storage unit, the temperature information calculation device comprises a quality information storage unit comprising a quality information storage unit comprising a quality information storage unit comprising a quality information calculation device comprising a quality information calculation device comprising a quality information storage unit

[0106] (4) The temperature information calculation method according to (1), wherein the time-temperature indicator has the characteristic that, within a certain temperature range, the rate at which the color density changes increases as the temperature rises.

[0107] (5) The temperature information calculation method according to (1), wherein the time temperature indicator has the characteristic that the color density increases monotonically with time over a certain time range.

[0108] (6) The temperature information calculation method according to (1), wherein the time temperature indicator comprises an ink portion on which the thermochromic ink is printed, a reference color portion on which a first color whose color density does not change is printed, and a reference color portion on which a second color whose color density does not change is printed, and in the color density acquisition step, the color information acquisition unit reads a read color which is the color of the ink portion, a reference color which is the color of the reference color portion, and a reference color which is the color of the reference color portion, the color information acquisition unit corrects the read color and the reference color using the reference color, and calculates the color density using the corrected read color and the corrected reference color.

[0109] (7) The temperature information calculation method according to (1), wherein in the calculation step, the temperature information calculation unit calculates the average temperature of two time points or a temperature related to the average temperature as information about the temperature.

[0110] (8) The temperature information calculation method according to (1), wherein in the calculation step, the temperature information calculation unit calculates the cumulative temperature between two time points or a temperature related to the cumulative temperature as information about the temperature.

[0111] (9) The temperature information calculation method according to (1), wherein the temperature information calculation device comprises an output unit, and the output unit has an output step of outputting information about the temperature calculated by the temperature information calculation unit and information about the quality of the object calculated by the temperature information calculation unit.

[0112] (10) The temperature information calculation method according to (9), wherein in the output step, the output unit displays at least one of the following: a message indicating that the quality of the object is within a predetermined quality range, a message indicating that the quality of the object has fallen outside a predetermined quality range, the number of days until the quality of the object reaches a predetermined quality range, and the number of days elapsed since the quality of the object entered a predetermined quality range.

[0113] (11) The temperature information calculation method according to (1), wherein the temperature information calculation device includes an input unit for a user to input information to the temperature information calculation device, and in the calculation step, the temperature information calculation unit calculates information about the quality of the object using the information about the quality of the object input by the user.

[0114] (12) The temperature information calculation device comprises a database storing the variety and quality of the object, and an output unit, wherein the calculation step includes an output step in which the temperature information calculation unit refers to the database to obtain a variety corresponding to the quality of the object input by the user and information about the quality of this variety, and the output unit displays the variety and information about the quality of this variety obtained by the temperature information calculation unit.

[0115] (13) The temperature information calculation device comprises an AI that has learned the variety and quality of the object, and an output unit, wherein the calculation step includes an output step in which the temperature information calculation unit uses the AI ​​to obtain a variety corresponding to the quality of the object input by the user and information about the quality of this variety, and the output unit displays the variety and information about the quality of this variety obtained by the temperature information calculation unit.

[0116] (14) The temperature information calculation method according to (2), wherein the temperature information calculation device is connected to a server via a communication network, the server stores the label type from the unique ID information, and in the calculation step, the temperature information calculation unit uses the master curve for the thermochromic ink obtained from the label type stored in the server.

[0117] (15) A temperature information calculation device comprising: a time-temperature indicator on which a thermochromic ink is printed and which changes in color density according to changes in temperature and time is attached to an object; a color information acquisition unit that acquires the color density indicated by the time-temperature indicator; a color information storage unit that stores in advance master curves, which are curves representing the relationship between the color density indicated by the time-temperature indicator and time, for a plurality of temperatures; and a temperature information calculation unit, wherein the temperature information calculation unit calculates information about the temperature of the environment in which the object is placed and information about the quality of the object based on the color density acquired by the color information acquisition unit and the master curve stored in the color information storage unit.

[0118] (16) The temperature information calculation device described in (15), comprising a portable information terminal with a camera function.

[0119] (17) The temperature information calculation device described in (15), which is connected to a server via a communication network, and the temperature information calculation unit is provided on the server.

[0120] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all of the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to delete parts of the configuration of each embodiment, or to add or replace other configurations.

[0121] 100...Temperature information calculation device, 110...Color information acquisition unit, 120...Color information storage unit, 130...Temperature information calculation unit, 140...Unique ID information acquisition unit, 150...Quality information storage unit, 160...Input unit, 170...Output unit, 171...Screen, 180...Database, 190...AI, 200...Server, 400...Time temperature indicator, 401...Ink unit, 402...Reference color section, 403...Reference color section.

Claims

1. A temperature information calculation device comprising: a storage unit that pre-stores master curves representing the relationship between color density and time at predetermined temperatures indicated by a time-temperature indicator for multiple temperatures; and a calculation unit that calculates information regarding the temperature of the environment in which the object is placed, using information regarding the color density read from a time-temperature indicator attached to the object and the time read, information regarding the color density at a reference point and the time at that reference point, and the master curve stored in the storage unit.

2. The temperature information calculation device according to claim 1, wherein the calculation unit calculates the average temperature at the time read from the reference point.

3. The temperature information calculation device according to claim 2, wherein the calculation unit calculates the integrated temperature from the average temperature and the time read from the reference point.

4. The temperature information calculation device according to claim 3, wherein the reference point is a preset initial value or the time when the time-temperature indicator was previously read, and the color density and time information at the reference point are stored in association with a unique ID assigned to the object together with the time-temperature indicator.

5. The temperature information calculation device according to claim 4, which identifies the thermochromic ink used in the time-temperature indicator from the unique ID and uses a master curve corresponding to the identified thermochromic ink.

6. A temperature information calculation device according to claim 1, comprising a quality information recording unit that pre-stores the relationship between the quality and color density of an object, and which calculates the quality of an object using the color density read from a time-temperature indicator.

7. A temperature information calculation device according to claim 4, comprising a quality information recording unit that pre-stores the relationship between the quality and color density of an object, and calculating the quality from the relationship of quality information in an object linked to a unique ID using the color density read from a time-temperature indicator.

8. The temperature information calculation device according to claim 6 or 7, wherein the storage unit stores the relationship between color density and the quality of the object, and the calculation unit calculates the time to reach a predetermined quality using the color density read from the time temperature indicator and a master curve related to the storage temperature of the object.

9. The temperature information calculation device according to claim 8, further comprising an output unit that outputs information calculated by the calculation unit to a display unit, wherein the display unit displays at least one of the following: a message indicating that the quality of the object is within a predetermined quality range; a message indicating that the quality of the object has fallen outside a predetermined quality range; the number of days until the quality of the object reaches a predetermined quality range; and the number of days elapsed since the quality of the object entered a predetermined quality range.

10. The temperature information calculation device according to claim 9, wherein the temperature information calculation device is a portable terminal comprising: a display unit; a color information acquisition unit for acquiring color density at a predetermined temperature indicated by a time temperature indicator; a calculation unit; and a display unit.

11. The temperature information calculation device according to claim 8, wherein the temperature information calculation device is a server or cloud configured to communicate with a terminal equipped with a color density acquisition unit at a predetermined temperature indicated by a time temperature indicator.

12. A temperature information calculation method comprising: a step of reading the color density from a time-temperature indicator attached to an object, a step of obtaining information about the time in the step of reading the color density, a step of obtaining information about the color density and time at a reference point, and a step of calculating information about the temperature of the environment in which the object is placed using a master curve that is close to the reference point and the amount of change in color density and time at the time of measurement obtained in the previous step.

13. The temperature information calculation method according to claim 12, wherein the reference point is a preset initial value or the time when the time-temperature indicator was previously read, and in the step of acquiring information on color density and time at the reference point, information on color density and time at the reference point is acquired from a storage unit that stores information on color density and time at the reference point in association with a unique ID assigned to the object along with the time-temperature indicator.

14. A quality control method utilizing the temperature information calculation method described in claim 13, comprising: a step of calculating the quality of the object using the color density obtained in a step of reading the color density from a time temperature indicator attached to the object; a step of calculating the time to reach a predetermined quality from a master curve related to the storage temperature; and a step of displaying at least one of the following: a message indicating that the quality of the object is within a predetermined quality range; a message indicating that the quality of the object has fallen outside a predetermined quality range; the number of days until the quality of the object reaches a predetermined quality range; and the number of days elapsed since the quality of the object entered a predetermined quality range.

15. A quality control method according to claim 14, comprising the steps of: calculating information about the quality of an object using information about the quality of the object entered by a user; referring to a database in which the varieties and quality of objects are stored to obtain a variety corresponding to the quality of the object entered by the user, and information about the quality of that variety; and displaying the obtained variety and information about the quality of the obtained variety.

16. The quality control method according to claim 14, comprising: a step of using an AI that has learned the varieties and quality of an object to obtain a variety corresponding to the quality of an object input by a user, and information about the quality of that variety; and a step of displaying the obtained variety and the information about the quality of that variety.

17. A quality control system that traces the storage conditions of each event by performing the temperature information calculation method described in claim 12 at the start and end of each logistics event.

18. The method for calculating temperature information according to claim 12, wherein the time-temperature indicator has thermochromic ink printed on it and has the characteristic of monotonically increasing color density in response to changes in temperature and time.

19. The method for calculating temperature information according to claim 18, wherein the time-temperature indicator has the characteristic that the rate at which the color density changes increases as the temperature rises within a certain temperature range.

20. The temperature information calculation method according to claim 18, wherein the time temperature indicator comprises an ink portion on which the thermochromic ink is printed, a reference color portion on which a first color whose color density does not change is printed, and a reference color portion on which a second color whose color density does not change is printed, and in the step of reading the color density, the reading color which is the color of the ink portion, the reference color which is the color of the reference color portion, the reading color and the reference color which is the color of the reference color portion, the reading color and the reference color are corrected using the reference color, and the color density is calculated using the corrected reading color and the corrected reference color.

21. A quality control system that uses the color of the ink portion of an accumulated temperature indicator, a master curve showing the relationship between the number of days at a predetermined temperature and the color density of the ink portion, and the relationship between the quality of the object and its color density to calculate and present to the user the date by which the product will reach its desired quality, such as the appropriate storage temperature and optimal consumption time.

22. The quality control system according to claim 21, which updates the relationship between quality and color density by learning user preferences using AI.

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