Inspection device, inspection method, and food manufacturing method

Abstract

To provide an inspection device, inspection method, and food manufacturing method capable of suppressing mixture of a foreign matter into a frozen object.SOLUTION: An inspection device includes: a terahertz light source for radiating a terahertz wave to a frozen object; a detector for simultaneously detecting the terahertz wave passing through the object or the terahertz wave reflected against the object at a plurality of positions of the object; and an identification section for identifying foreign matters mixed in the object, based on the terahertz waves detected by the detector.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device, an inspection method, and a food manufacturing method. [Background technology]

[0002] Food inspection devices and inspection methods that utilize electromagnetic wave irradiation are known (for example, Patent Document 1). The food inspection device described in Patent Document 1 has a variable wavelength electromagnetic wave generating means that can irradiate electromagnetic waves with frequencies in the range of 0.1 to 10 THz that are specific to the constituent elements of food, and a detecting means for electromagnetic waves of said frequencies, and is configured to irradiate the electromagnetic waves onto at least a part of a food sample that has been processed into a predetermined shape, and measure the transmission or reflection intensity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-172775 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to provide an inspection device, an inspection method, and a food manufacturing method that can prevent foreign matter from being mixed into frozen objects. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to an inspection device that inspects frozen objects placed on a conveyor, the inspection device including: a terahertz light source that irradiates the object with terahertz waves; a detector that simultaneously detects the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object; and an identification unit that identifies foreign matter that has become mixed in the object based on the terahertz waves detected by the detector.

[0006] Another aspect of the present disclosure relates to an inspection method for inspecting a frozen object placed on a conveyor, the inspection method comprising the steps of: irradiating the object with terahertz waves; simultaneously detecting the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object; and identifying foreign matter that has become mixed in the object based on the detected terahertz waves.

[0007] Another aspect of the present disclosure relates to a food manufacturing method comprising the steps of inspecting frozen objects placed on a conveyor and removing foreign matter from the inspected objects, wherein the inspecting step includes irradiating the object with terahertz waves, simultaneously detecting the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object, and identifying foreign matter that has been mixed into the object based on the detected terahertz waves. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to prevent foreign matter from being mixed into a frozen object. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an inspection device according to an embodiment. [Figure 2] FIG. 2 is a graph illustrating the transmittance of terahertz waves through spinach leaves. [Figure 3] FIG. 3 is a graph illustrating the transmittance of terahertz waves through edamame pods. [Figure 4] FIG. 4(a) is a schematic diagram showing an object before image processing is performed, and FIG. 4(b) is a schematic diagram showing an object after image processing is performed. [Figure 5] FIG. 5 is a flowchart illustrating an inspection method according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described below with reference to the drawings. FIGS. 1 to 5 are diagrams illustrating one embodiment. The following figures are schematic illustrations. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, appropriate modifications can be made within the scope of the technical concept. In the following figures, identical parts are denoted by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each component described in this specification are examples of an embodiment and are not limited thereto. They can be selected and used as appropriate. In this specification, terms specifying shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are intended to include not only their strict meanings but also substantially the same states.

[0011] Inspection Equipment First, an inspection device according to one embodiment will be described with reference to Figure 1. Inspection device 1 according to the present disclosure uses terahertz waves to inspect an object 3 placed on a conveyor 2. Here, in this specification, "terahertz waves" refers to electromagnetic waves with a frequency of 0.03 THz or more and 10 THz or less.

[0012] The "object" may also be a frozen food ingredient. The "food ingredient" is not particularly limited to a specific type of food ingredient. Therefore, the food ingredient may include, for example, one or more of vegetables such as spinach, eggs, seafood, meat, beans, fruits, and grains such as rice and flour. The size of the object may be, for example, approximately 100 mm x 100 mm. In this embodiment, as described below, detector 20 simultaneously detects terahertz waves passing through the object at multiple positions on the object. Therefore, even objects with a large surface area can be inspected in a short time.

[0013] Here, terahertz waves are strongly absorbed by water, which is a polar molecule. In other words, when terahertz waves are irradiated onto an unfrozen substance, the terahertz waves are absorbed by the water in the substance. For this reason, for example, among the terahertz waves that have passed through a substance, there may be no difference in the transmittance between the terahertz waves that have passed through a portion containing foreign matter and the terahertz waves that have passed through a portion not containing foreign matter.

[0014] On the other hand, when water contained in a substance is frozen, the water's absorption rate of terahertz waves decreases due to the binding of water molecules. In other words, freezing a substance increases the transmittance of terahertz waves through the substance. In this specification, freezing water contained in a substance is also simply referred to as "freezing a substance."

[0015] For example, as shown by the group of "◯" points in Figure 2, when spinach is at room temperature (25°C), the maximum transmittance of terahertz waves is approximately 10% or less in the frequency range of 0.3 THz to 1.1 THz. On the other hand, when the water contained in spinach is frozen, the maximum transmittance of terahertz waves increases to approximately 40% in the frequency range of 0.3 THz to 1.1 THz. Thus, when frozen spinach is irradiated with terahertz waves with a frequency of 0.3 THz to 1.1 THz, the absorption of terahertz waves by the spinach is suppressed, and the transmittance of terahertz waves increases. Furthermore, when terahertz waves are irradiated onto water, the transmittance of terahertz waves through water increases as the frequency of the terahertz waves decreases. Furthermore, for terahertz waves with a frequency of approximately 0.1 THz, the transmittance of terahertz waves in an unfrozen liquid state differs by approximately 1,000 times from the transmittance of terahertz waves in a frozen solid state. For this reason, depending on the substance, for example, when terahertz waves have a frequency of about 0.1 THz, the transmittance of the terahertz waves when the substance is not frozen may differ by several hundred times from the transmittance of the terahertz waves when the substance is frozen.

[0016] Therefore, by irradiating terahertz waves of a predetermined frequency onto a frozen substance, a difference will arise between the transmittance of the terahertz waves that pass through the substance in parts containing foreign matter (the point group indicated by ``+'' in Figure 2) and the transmittance of the terahertz waves that pass through parts not containing foreign matter (the point group indicated by ``●'' in Figure 2), making it easier to detect foreign matter that has become mixed into the substance.

[0017] That is, for example, among terahertz waves that have passed through a substance, the transmittance of terahertz waves that have passed through a portion containing foreign matter is not the transmittance for the substance itself, but is a transmittance that depends on the physical properties of the foreign matter. On the other hand, among terahertz waves that have passed through a substance, the transmittance of terahertz waves that have passed through a portion not containing foreign matter is the transmittance for the substance itself. Therefore, by irradiating terahertz waves onto a frozen substance and measuring the transmittance of the terahertz waves that have passed through the substance, it is possible to more easily detect foreign matter that has been mixed into the substance.

[0018] Here, most food ingredients contain water. For this reason, the present inventors came up with the idea that irradiating frozen food ingredients with terahertz waves is useful for detecting foreign matter mixed in food ingredients. That is, when terahertz waves are irradiated onto frozen food ingredients, the terahertz waves pass through the food ingredients at a predetermined transmittance in areas where no foreign matter is mixed in. On the other hand, if the food ingredients contain foreign matter (e.g., insects or hairs) that have a different shape from the food ingredients and a different terahertz wave transmittance than the food ingredients, the terahertz waves pass through the food ingredients at a transmittance different from the "predetermined transmittance" (i.e., a transmittance that depends on the physical properties of the foreign matter) in areas where the foreign matter is mixed in. As a result, foreign matter mixed in food ingredients can be detected by measuring the transmittance of the terahertz waves and the intensity of the transmitted light.

[0019] In this case, the frequency of the terahertz waves is preferably 0.03 THz or more and 2.0 THz or less. For example, when using terahertz waves with a frequency of approximately 0.03 THz, the transmittance of water in an unfrozen liquid state differs by several thousand times from that in a frozen solid state. Furthermore, it may be desirable to detect insects with a major axis of approximately 10 mm as foreign matter. In this case, a terahertz wave frequency of 0.03 THz or more theoretically makes it possible to detect insects of this size. This increases the transmittance of terahertz waves through frozen food materials and the transmitted light intensity of terahertz waves transmitted through frozen food materials. Therefore, for example, a large difference can be created between the transmittance of terahertz waves transmitted through portions containing foreign matter and the transmittance of terahertz waves transmitted through portions not containing foreign matter. As a result, foreign matter in food materials can be more easily detected.

[0020] Furthermore, for example, when the food ingredient is spinach, as described above, when terahertz waves with a frequency of 0.03 THz or more and 1.1 THz or less are irradiated, the transmittance of the terahertz waves through the spinach is high. Therefore, when the food ingredient is spinach, the frequency of the terahertz waves is preferably 0.03 THz or more and 1.1 THz or less. Furthermore, when the food ingredient is edamame, as shown in FIG. 3, when terahertz waves with a frequency of 0.3 THz or more and 2.0 THz or less are irradiated, the absorption of the terahertz waves by the edamame is suppressed, and the transmittance of the terahertz waves is high. Therefore, when the food ingredient is edamame, as with spinach, the frequency of the terahertz waves is preferably 0.03 THz or more and 2.0 THz or less.

[0021] 1 again, the inspection device 1 includes a terahertz light source 10 that irradiates the object 3 with terahertz waves, a detector 20 that simultaneously detects the terahertz waves that pass through the object 3 at multiple positions on the object 3, and an identification unit 30 that identifies foreign matter 4 that has become mixed in the object 3 based on the terahertz waves detected by the detector 20. Of these, the identification unit 30 is incorporated into the control unit 40.

[0022] (Terahertz light source) The terahertz light source 10 irradiates the object 3 placed on the conveyor 2 with terahertz waves. In this embodiment, the terahertz light source 10 is capable of irradiating the terahertz waves in a planar or linear manner. This allows the detector 20 to detect the terahertz waves at multiple positions on the object 3 simultaneously.

[0023] An example of a terahertz light source 10 capable of such planar irradiation is the IMPATT-100 / 80-H / F (product name), oscillator: IMPATT diode, frequency: up to 0.1 THz, output: up to 80 mW) manufactured by TeraSense. Also, an example of a terahertz light source 10 capable of linear irradiation is the IMPATT-100-LS-fH / mirror (product name), oscillator: IMPATT diode, frequency: up to 0.1 THz, output: up to 110 mW) manufactured by TeraSense.

[0024] (Detector) The detector 20 detects the terahertz waves that pass through the object 3 to obtain image data of the object 3. In this case, the detector 20 may obtain image data of the object 3 based on the transmitted light intensity of the terahertz waves that pass through the object 3. In this embodiment, the detector 20 simultaneously detects the terahertz waves at multiple positions on the object 3. This allows the entire object 3 to be inspected efficiently, and makes it easier to identify the position of the foreign object 4 if it is found in the object 3.

[0025] Furthermore, the detector 20 may detect terahertz waves by utilizing surface plasmon resonance. This allows for highly accurate detection of terahertz waves. In this case, the detector 20 may include a measurement sensor 21 having a periodic structure (e.g., a fine uneven structure) formed on its surface using a metal. In this case, the periodic structure using a metal may be formed in a stripe pattern, for example. The measurement sensor 21 may also include a multiple quantum well structure (MQW (Multiple Quantum Well)). In this case, the multiple quantum well structure may be a so-called GaAs / AlGaAs structure including a core layer in which GaAs layers and AlGaAs layers are alternately stacked.

[0026] The detector 20 preferably includes a plurality of measurement sensors 21. This makes it easier to simultaneously detect terahertz waves passing through the object 3 at a plurality of positions on the object 3. This reduces the time required to measure the terahertz waves. In particular, even if the size of the object 3 is large, the terahertz waves can be measured over the entire object 3 in a short time.

[0027] The measurement sensor 21 is preferably a sensor array made up of a plurality of semiconductor sensor elements, which can increase the response speed of the measurement sensor 21 and reduce noise.

[0028] As such a detector 20, for example, an area camera (TeraSense, product name: Tera-1024, number of elements: 1024 (32 × 32), element size: 1.5 mm × 1.5 mm, sensitivity: 50 kV / W (1 nW / √Hz), readout speed: maximum 50 Hz, compatible frequency: 50 GHz to 0.7 THz) can be used. Also, as the detector 20, for example, a line camera (TeraSense, product name: TeraFAST-100, element size: 1.3 mm × 3 mm) or (TeraSense, product name: TeraFAST-300, element size: 0.5 mm × 0.5 mm) can be used.

[0029] (Identification section) The identification unit 30 identifies the foreign matter 4 mixed in the object 3 based on the terahertz waves detected by the detector 20. Specifically, the identification unit 30 identifies the foreign matter 4 from the image data acquired by the detector 20. The identification unit 30 may be integrated with the detector 20 described above.

[0030] In this embodiment, as shown in FIG. 1 , the identification unit 30 includes a storage unit 31 and an analysis unit 32. The storage unit 31 may be a memory such as a ROM or RAM. The storage unit 31 may store the transmittance of terahertz waves passing through the object 3 and the transmitted light intensity of the terahertz waves passing through the object 3. That is, when spinach is to be inspected as the object 3, the storage unit 31 may store the transmittance of terahertz waves passing through the spinach and the transmitted light intensity of the terahertz waves passing through the spinach. The storage unit 31 may also store the transmittance of terahertz waves passing through a foreign object 4 and the transmitted light intensity of the terahertz waves passing through the foreign object 4. That is, if foreign matter 4 is to be detected as a common cutworm larva, the memory unit 31 may store the transmittance of terahertz waves passing through the common cutworm larvae and the transmitted light intensity of terahertz waves that have passed through the common cutworm larvae.

[0031] The analysis unit 32 identifies the foreign matter 4 based on the detected terahertz waves. For example, the analysis unit 32 may identify the foreign matter 4 based on the transmitted light intensity of the terahertz waves detected by the detector 20. In this case, the analysis unit 32 may identify the foreign matter 4 by performing image processing on image data related to the transmitted light intensity of the terahertz waves detected by the detector 20.

[0032] There are no particular limitations on the method of image processing of the image data by the recognition unit 30. For example, image processing may be performed by converting the image data to a grayscale, and the foreign matter 4 may be emphasized by appropriately setting the gradation of the scale.

[0033] The transmittance of terahertz waves passing through a material and the transmitted light intensity of the terahertz waves passing through a material vary depending on the material. Therefore, for example, by performing image processing on image data relating to the transmitted light intensity of the terahertz waves passing through the object 3, a foreign object 4 contained in the object 3 can be identified. That is, for example, as shown in FIG. 4(a), if a foreign object 4 is present in the object 3, the foreign object 4 may not be detectable from the outside. However, even in such a case, the terahertz waves irradiated onto the foreign object 4 may be absorbed by the foreign object 4 without passing through the foreign object 4. Therefore, the detected transmitted light intensity of the terahertz waves is reduced in the area where the foreign object 4 is present. Therefore, for example, by performing image processing on image data relating to the transmitted light intensity of the terahertz waves passing through the object 3, a foreign object 4 present in the object 3 can be identified, as shown in FIG. 4(b).

[0034] For example, if the objects 3 are leafy vegetables such as spinach, overlapping of the objects 3 may reduce the intensity of the transmitted light of the detected terahertz waves even in areas where no foreign matter 4 is present. For this reason, in the case of objects 3 that may overlap, the overlapping of the objects 3 may be inspected using visible light, infrared light, or other measurement technology in addition to inspection using terahertz waves. This can improve the detection accuracy of inspection using terahertz waves.

[0035] Here, the identification unit 30 may identify the foreign matter 4 based on the transmittance of the terahertz waves passing through the object 3 and the transmitted light intensity of the terahertz waves that have passed through the object 3, which are stored in the memory unit 31. In this case, for example, first, terahertz waves of a predetermined frequency are irradiated onto the object 3 (e.g., spinach), and the transmitted light intensity of the terahertz waves that have passed through the object 3 is measured. Next, based on the measured transmitted light intensity, a first numerical range of the transmitted light intensity that is used to identify the object 3 is set. This first numerical range is stored in the memory unit 31. Then, the analysis unit 32 may identify a portion of the object 3 where the transmitted light intensity is outside the first numerical range as a portion containing the foreign matter 4.

[0036] Furthermore, the identification unit 30 may identify the foreign matter 4 based on the transmittance of the terahertz waves passing through the foreign matter 4 or the transmitted light intensity of the terahertz waves that have passed through the foreign matter 4, which are stored in the memory unit 31. In this case, for example, first, terahertz waves of a predetermined frequency are irradiated onto the foreign matter 4 (e.g., larvae of the common cutworm), and the transmitted light intensity of the terahertz waves that have passed through the foreign matter 4 is measured. Next, based on the measured transmitted light intensity, a second numerical range of the transmitted light intensity that is used to identify the foreign matter 4 is set. This second numerical range is stored in the memory unit 31. Then, the analysis unit 32 may identify a portion of the target object 3 whose transmitted light intensity falls within the second numerical range as a portion containing the foreign matter 4.

[0037] As described above, the recognition unit 30 is incorporated in the control unit 40. Here, the control unit 40 may be configured with, for example, a CPU (Central Processing Unit) that operates based on a predetermined program. Specifically, the control unit 40 may further include a frequency determination unit 41, an irradiation control unit 42, a detection signal receiving unit 43, and a removal control unit 44.

[0038] Of these, frequency determination unit 41 determines the frequency of the terahertz waves to be irradiated onto object 3. The frequency is set to a value that allows foreign matter 4 contained in object 3 to be detected when object 3 is frozen.

[0039] The irradiation control unit 42 controls the operation of the terahertz light source 10. The irradiation control unit 42 may control the timing at which the terahertz light source 10 irradiates terahertz waves, the frequency of the terahertz waves, etc. The irradiation control unit 42 controls the terahertz light source 10 so that the terahertz light source 10 irradiates terahertz waves of the frequency set by the frequency determination unit 41.

[0040] The detection signal receiving unit 43 receives a signal from the detector 20. That is, when the detector 20 detects terahertz waves that have passed through the object 3, information about the detected terahertz waves (for example, transmitted light intensity) is transmitted as a signal to the control unit 40. Then, the detection signal receiving unit 43 receives the transmitted signal.

[0041] The removal control unit 44 controls the operation of a removal means (not shown). For example, the removal control unit 44 operates the removal means, which can remove the foreign matter 4 from the inspected object 3. The removal control unit 44 may be configured to issue a warning to an operator, for example, by sound such as an alarm, light, or vibration, when the analysis unit 32 of the identification unit 30 determines that the foreign matter 4 is present in the object 3. In this case, the operator who has received the warning may manually remove the foreign matter 4.

[0042] Next, the foreign matter 4 will be described. The foreign matter 4 may be organic. In this case, the organic matter may be, for example, an insect such as a cutworm larva, or may be hair. The foreign matter 4 may also be inorganic. In this case, the inorganic matter may be, for example, a metal or a stone. In this embodiment, by using terahertz waves, the foreign matter 4 can be identified even if it is inorganic. Therefore, the step of inspecting the target object 3 with a metal detector or X-ray inspection machine can be omitted.

[0043] The size of the identifiable foreign object 4 can be determined based on the element size of the detector 20. For example, if the element size of the detector 20 is 1.5 mm x 1.5 mm, the length or width of the identifiable foreign object 4 is 1.5 mm or more.

[0044] Inspection method Next, the operation of this embodiment configured as described above, that is, the method for inspecting the object 3 and the food manufacturing method, will be described with reference to FIG.

[0045] First, the frequency determination unit 41 of the control unit 40 determines the frequency of the terahertz waves to be irradiated onto the object 3 (frequency determination step, reference numeral S1 in FIG. 5). At this time, the terahertz light source 10 first irradiates the object 3 with terahertz waves of a predetermined frequency. This provides information on frequencies at which the terahertz waves that pass through the object 3 have a high transmittance and frequencies at which the transmitted light intensity of the terahertz waves that have passed through the object 3 is high. Then, based on the obtained information, the frequency determination unit 41 determines the frequency of the terahertz waves to be irradiated onto the object 3. At this time, for example, if the object 3 is frozen spinach, the frequency of the terahertz waves is preferably 0.03 THz or more and 1.1 THz or less. Furthermore, for example, if the object 3 is frozen edamame beans, the frequency of the terahertz waves is preferably 0.03 THz or more and 2.0 THz or less. At this time, it is preferable to measure in advance the transmittance of the terahertz waves passing through the conveyor 2 and the transmitted light intensity of the terahertz waves that have passed through the conveyor 2. This can improve the inspection accuracy for identifying the foreign matter 4. The frequency determination unit 41 may further determine the frequency taking into consideration the ease of detection of the foreign matter 4, thereby improving the detection accuracy of the inspection device 1.

[0046] Next, the inspection device 1 inspects the frozen object 3 placed on the conveyor 2 (inspection step, symbol S2 in FIG. 5).

[0047] In the inspection process, first, the terahertz light source 10 irradiates the object 3 with terahertz waves (irradiation process, reference numeral S21 in FIG. 5). At this time, the irradiation control unit 42 operates the terahertz light source 10, so that the terahertz light source 10 irradiates the object 3 with terahertz waves. The irradiation control unit 42 controls the terahertz light source 10 so that the terahertz light source 10 irradiates the object 3 with terahertz waves of the frequency set by the frequency determination unit 41.

[0048] Next, detector 20 simultaneously detects the terahertz waves transmitted through object 3 at multiple positions on object 3 (detection step, reference numeral S22 in FIG. 5). At this time, detector 20 detects the terahertz waves transmitted through object 3, and measures, for example, the transmitted light intensity of the terahertz waves. Information on the terahertz waves detected by detector 20 is then transmitted as a signal to control unit 40, and detection signal receiving unit 43 of control unit 40 receives the signal.

[0049] Next, the identification unit 30 identifies the foreign matter 4 mixed in the object 3 based on the detected terahertz waves (identification step, reference numeral S23 in FIG. 5). At this time, for example, the analysis unit 32 of the identification unit 30 may identify the foreign matter 4 by performing image processing on image data relating to the transmitted light intensity of the terahertz waves detected by the detector 20.

[0050] Furthermore, the analysis unit 32 may identify the foreign matter 4 based on the transmitted light intensity of the terahertz waves that have passed through the object 3 and that is stored in the storage unit 31. For example, the analysis unit 32 may identify a portion of the object 3 where the transmitted light intensity is outside a preset numerical range (the above-described first numerical range) as a portion where the foreign matter 4 has been mixed in.

[0051] Furthermore, the analysis unit 32 may identify the foreign matter 4 based on the transmitted light intensity of the terahertz waves that have passed through the foreign matter 4, which is stored in the storage unit 31. For example, the analysis unit 32 may determine that a portion of the target object 3 in which the transmitted light intensity is within a predetermined numerical range (the second numerical range described above) is a portion in which the foreign matter 4 has been mixed in.

[0052] Thereafter, for example, the removal control unit 44 operates a removal means (not shown), which removes the foreign matter 4 from the inspected object 3 (removal step, reference numeral S3 in FIG. 5). In this way, a food product from which the foreign matter 4 has been removed is produced. Note that the removal control unit 44 may issue a warning to an operator, and the operator who has received the warning may then manually remove the foreign matter 4.

[0053] As described above, according to the present embodiment, the inspection device 1 includes the terahertz light source 10 that irradiates the frozen object 3 with terahertz waves, the detector 20 that simultaneously detects the terahertz waves that have passed through the object 3 at multiple positions on the object 3, and the identification unit 30 that identifies the foreign matter 4 that has entered the object 3 based on the terahertz waves detected by the detector 20. This makes it possible to accurately detect the foreign matter 4 that has entered the object 3, and to prevent the foreign matter 4 from entering the object 3. In particular, the detector 20 simultaneously detects the terahertz waves that have passed through the object 3 at multiple positions on the object 3. This makes it possible to accurately detect the foreign matter 4 that has entered the object 3 in a short period of time, even for an object 3 with a large surface area, and to prevent the foreign matter 4 from entering the object 3.

[0054] Furthermore, since the object 3 placed on the conveyor 2 is inspected, the object 3 can be inspected on a production line in a food manufacturing factory (processing factory) or the like. Furthermore, since non-destructive inspection of the object 3 is possible without destroying the object 3, and the object 3 can be inspected non-invasively, when the object 3 is a food ingredient, food waste can be reduced.

[0055] Furthermore, it is difficult for an X-ray inspection machine to detect foreign objects such as insects and plastics that have become mixed in, for example, spinach, edamame, or broccoli. For this reason, inspectors generally inspect for the presence of foreign objects 4 visually. In contrast, in this embodiment, terahertz waves are used to inspect the object 3, thereby enabling accurate detection of foreign objects 4 that are difficult to detect with metal detectors or X-ray inspection machines. This saves inspectors the trouble of visually inspecting for the presence of foreign objects 4. This can improve the productivity of the final product.

[0056] Furthermore, according to this embodiment, detector 20 detects terahertz waves by utilizing surface plasmon resonance, thereby enabling terahertz waves to be detected with high accuracy.

[0057] Furthermore, according to this embodiment, the detector 20 includes a plurality of measurement sensors 21. This makes it easier to simultaneously detect terahertz waves that pass through the object 3 at a plurality of positions on the object 3. This reduces the time required to measure the terahertz waves. In particular, even if the size of the object 3 is large, the terahertz waves can be measured over the entire object 3 in a short time.

[0058] Furthermore, according to this embodiment, the measurement sensor 21 is a sensor array made up of a plurality of semiconductor sensor elements, which increases the response speed of the measurement sensor 21 and reduces noise.

[0059] Furthermore, according to this embodiment, the object 3 is a frozen food material, and the frequency of the terahertz waves is 0.03 THz or more and 2.0 THz or less. This makes it possible to increase the transmittance of the terahertz waves through the frozen food material and the transmitted light intensity of the terahertz waves that have passed through the frozen food material. Therefore, for example, it is possible to create a large difference between the transmittance of the terahertz waves that have passed through a portion containing foreign matter 4 and the transmittance of the terahertz waves that have passed through a portion not containing foreign matter 4. As a result, it becomes easier to find foreign matter 4 that has been mixed into the food material.

[0060] Furthermore, according to this embodiment, the food material is a vegetable. Here, vegetables may contain a lot of water. For this reason, it is usually difficult to inspect for foreign matter 4 mixed in the vegetable using terahertz waves. In contrast, in this embodiment, by freezing the vegetable, it is possible to inspect for foreign matter 4 mixed in the vegetable using terahertz waves.

[0061] Furthermore, according to this embodiment, the foreign matter 4 is an organic matter. Here, it is difficult to detect organic matter using a metal detector or an X-ray inspection machine. In contrast, in this embodiment, by inspecting the object 3 using terahertz waves, it is possible to accurately detect the foreign matter 4, which has been difficult to detect using a metal detector or an X-ray inspection machine.

[0062] In the above-described embodiment, an example has been described in which detector 20 detects terahertz waves that pass through object 3, but this is not limiting. For example, detector 20 may detect terahertz waves that are reflected by object 3. In this case as well, foreign matter 4 that has become mixed in object 3 can be accurately detected, and the mixing of foreign matter 4 into object 3 can be prevented.

[0063] The present disclosure is not limited to the above-described embodiments and variations. For example, various modifications may be made to each element of the above-described embodiments and variations. Furthermore, embodiments of the present disclosure also include configurations that include components other than those described above. Furthermore, embodiments of the present disclosure also include configurations that do not include some of the above-described components. Furthermore, embodiments of the present disclosure also include configurations that include some components included in one embodiment of the present disclosure and some components included in another embodiment of the present disclosure. Therefore, components included in the above-described embodiments and variations, and in other embodiments of the present disclosure, may be combined, and such combinations are also included in embodiments of the present disclosure. Furthermore, the effects achieved by the present disclosure are not limited to the above-described effects, and unique effects may also be achieved depending on the specific configuration of each embodiment. Thus, various additions, modifications, and partial deletions are possible to the elements described in the claims, specification, abstract, and drawings, as long as they do not deviate from the technical concept and spirit of the present disclosure.

[0064] [Note] As is clear from the above, the present disclosure includes the following aspects.

[0065] (Aspect 1) One aspect of the present disclosure relates to an inspection device that inspects frozen objects placed on a conveyor, the inspection device including: a terahertz light source that irradiates the object with terahertz waves; a detector that simultaneously detects the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object; and an identification unit that identifies foreign matter that has become mixed in the object based on the terahertz waves detected by the detector.

[0066] (Aspect 2) In one aspect of the present disclosure, the detector may detect the terahertz waves by utilizing surface plasmon resonance.

[0067] (Aspect 3) In one aspect of the present disclosure, the detector may include a plurality of measurement sensors.

[0068] (Aspect 4) In one aspect of the present disclosure, the measurement sensor may be a sensor array made up of a plurality of semiconductor sensor elements.

[0069] (Aspect 5) In one aspect of the present disclosure, the target object may be a frozen food ingredient, and the frequency of the terahertz waves may be 0.03 THz or more and 2.0 THz or less.

[0070] (Aspect 6) In one aspect of the present disclosure, the food material may be a vegetable.

[0071] (Aspect 7) In one aspect of the present disclosure, the foreign matter may be an organic matter.

[0072] (Aspect 8) Another aspect of the present disclosure relates to an inspection method for inspecting a frozen object placed on a conveyor, the inspection method comprising the steps of: irradiating the object with terahertz waves; simultaneously detecting the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object; and identifying foreign matter that has become mixed in the object based on the detected terahertz waves.

[0073] (Aspect 9) Another aspect of the present disclosure relates to a food manufacturing method comprising the steps of inspecting frozen objects placed on a conveyor and removing foreign matter from the inspected objects, wherein the inspecting step includes irradiating the object with terahertz waves, simultaneously detecting the terahertz waves that pass through the object or the terahertz waves that are reflected from the object at multiple positions on the object, and identifying foreign matter that has been mixed into the object based on the detected terahertz waves. [Explanation of symbols]

[0074] 1. Inspection equipment 2 Conveyor 3. Object 4 Foreign object 10 Terahertz light source 20 Detector 21 Measurement Sensor 30 Identification unit

Claims

1. An inspection device for inspecting frozen objects placed on a conveyor, comprising: a terahertz light source that irradiates the object with terahertz waves; a detector that simultaneously detects the terahertz waves that pass through the object or the terahertz waves that are reflected by the object at a plurality of positions on the object; an identification unit that identifies a foreign substance mixed in the object based on the terahertz wave detected by the detector, the terahertz light source changes the frequency of the terahertz wave depending on the type of the object; the identification unit stores at least one of a transmittance of the terahertz wave transmitted through the object and a transmitted light intensity of the terahertz wave transmitted through the object, and at least one of a transmittance of the terahertz wave transmitted through the foreign matter and a transmitted light intensity of the terahertz wave transmitted through the foreign matter; the target object is spinach or edamame, When the object is spinach, the frequency of the terahertz waves is not less than 0.03 THz and not more than 1.1 THz, and when the object is edamame, the frequency of the terahertz waves is not less than 0.03 THz and not more than 2.0 THz; The foreign matter contains at least a larva of the common cutworm, the identification unit stores at least one of the transmittance of the terahertz waves passing through the larvae of the common cutworm and the transmitted light intensity of the terahertz waves passing through the larvae of the common cutworm.

2. The inspection device according to claim 1 , wherein the detector detects the terahertz waves by utilizing surface plasmon resonance.

3. The inspection device according to claim 1 or 2, wherein the detector includes a plurality of measurement sensors.

4. 4. The inspection device according to claim 3, wherein the measurement sensor is a sensor array made up of a plurality of semiconductor sensor elements.

5. The inspection device according to claim 1 , wherein the foreign matter is an organic substance.

6. 1. A method for inspecting frozen objects placed on a conveyor, comprising: irradiating the object with terahertz waves; simultaneously detecting the terahertz waves transmitted through the object or the terahertz waves reflected by the object at a plurality of positions on the object; and identifying a foreign substance present in the object based on the detected terahertz waves, In the step of irradiating the object with the terahertz waves, a frequency of the terahertz waves is changed depending on the type of the object; an identification unit that identifies the foreign matter stores at least one of a transmittance of the terahertz wave that passes through the object and a transmitted light intensity of the terahertz wave that has passed through the object, and at least one of a transmittance of the terahertz wave that passes through the foreign matter and a transmitted light intensity of the terahertz wave that has passed through the foreign matter; the target object is spinach or edamame, When the object is spinach, the frequency of the terahertz waves is not less than 0.03 THz and not more than 1.1 THz, and when the object is edamame, the frequency of the terahertz waves is not less than 0.03 THz and not more than 2.0 THz; The foreign matter contains at least a larva of the common cutworm, the identification unit stores at least one of the transmittance of the terahertz waves passing through the larvae of the common cutworm and the transmitted light intensity of the terahertz waves passing through the larvae of the common cutworm.

7. inspecting the frozen objects placed on the conveyor; removing foreign matter from the inspected object; The step of inspecting the object includes: irradiating the object with terahertz waves; simultaneously detecting the terahertz waves transmitted through the object or the terahertz waves reflected by the object at a plurality of positions on the object; and identifying a foreign substance present in the object based on the detected terahertz waves, In the step of irradiating the object with the terahertz waves, a frequency of the terahertz waves is changed depending on the type of the object; an identification unit that identifies the foreign matter stores at least one of a transmittance of the terahertz wave that passes through the object and a transmitted light intensity of the terahertz wave that has passed through the object, and at least one of a transmittance of the terahertz wave that passes through the foreign matter and a transmitted light intensity of the terahertz wave that has passed through the foreign matter; the target object is spinach or edamame, When the object is spinach, the frequency of the terahertz waves is not less than 0.03 THz and not more than 1.1 THz, and when the object is edamame, the frequency of the terahertz waves is not less than 0.03 THz and not more than 2.0 THz; The foreign matter contains at least a larva of the common cutworm, the identification unit stores at least one of the transmittance of terahertz waves passing through the common cutworm larvae and the transmitted light intensity of terahertz waves passing through the common cutworm larvae.

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