Foreign object detection device and foreign object detection method

Abstract

To provide a foreign matter detection device and foreign matter detection method, which enable detection of foreign matter mixed in solid food.SOLUTION: A foreign matter detection device is provided to clear the above challenge, the device comprising a near-infrared irradiation unit for locally irradiating solid food with near infrared light, an image capturing unit for capturing an image of the solid food transmitting the near-infrared light therethrough, and a detection unit configured to detect foreign matter having near-infrared transmittances lower than that of the solid food from the captured image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a foreign object detection device and a foreign object detection method. [Background technology]

[0002] In food production, contamination by foreign objects can be a serious problem. Therefore, in order to prevent food contaminated with foreign objects from being shipped, food manufacturers usually use inspection equipment such as foreign object detection equipment. In particular, X-ray inspection equipment and metal detectors are often used in food production because they can detect foreign objects without destroying the food.

[0003] For example, Patent Document 1 discloses an X-ray inspection device comprising a housing having an opening on both sides that serves as the entrance or exit for the food under test, and a pair of side covers each having an inclined surface and two side panels to cover the opening, an endless belt conveyor that transports the food under test from the entrance opening to the exit opening, an X-ray source within the housing that irradiates X-rays onto the food under test on the belt conveyor, and X-ray detection means that detects X-rays that have passed through the food under test and detects any foreign matter mixed in the food under test, wherein the endless belt conveyor is an endless belt conveyor that has an isosceles trapezoidal cross section and has an upward slope, an upper horizontal surface, a downward slope, and a lower horizontal surface, and the length and inclination of the upward slope and downward slope in the conveying direction are configured to be approximately equal to the length and inclination of the two inclined surfaces of the side covers.

[0004] Foreign object detection devices that detect foreign objects by irradiating them with illumination light may also be used. For example, Patent Document 2 discloses a food foreign object detection device that includes a transport means that transports food to a foreign object detection area, an imaging means that captures an image of the surface of the food from one side of the detection area, an illumination means that irradiates illumination light onto the food from one or both sides of the inspection area across the transport means, and an image processing means that performs image processing including binarization on the captured surface image. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-075830 [Patent Document 2] Special Publication No. 2008-541007 Summary of the Invention [Problem to be solved by the invention]

[0006] However, foreign objects such as bones, shells, seeds, stems, roots, and soft fibrous materials that may be mixed into solid foods such as meat, seafood, fruit pulp, and potatoes often have a density that is only slightly different from that of the solid food itself and do not usually contain metallic substances, making them difficult to detect with X-ray inspection machines or metal detectors. Detecting such foreign objects buried inside solid foods is particularly difficult. Furthermore, as described in Patent Document 1, X-ray inspection machines must minimize the leakage of X-rays to the outside, which poses safety and cost challenges.

[0007] Furthermore, the foreign object detection device described in Patent Document 2 essentially irradiates food with illumination light from two directions, above and below, to detect foreign objects such as hair or insects attached to the surface of the food, but this also has the problem that it is difficult to detect foreign objects such as those mentioned above that are buried inside solid food.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a foreign object detection device and a foreign object detection method that are capable of detecting foreign objects mixed in solid food. [Means for solving the problem]

[0009] In order to solve the above problems, the present inventors conducted extensive research and found that the above-mentioned foreign matter has a lower near-infrared light transmittance than the solid food that contains it. Furthermore, they found that an effective way to easily detect such foreign matter is to locally irradiate the solid food with near-infrared light, allow it to pass through, capture an image of the solid food that has locally transmitted near-infrared light, and use the captured image to detect foreign matter, thereby completing the present invention.

[0010] That is, the present invention provides the following (1) to (11). (1) A foreign object detection device that detects foreign objects that have been mixed into solid food and have a lower near-infrared light transmittance than the solid food, comprising a near-infrared light irradiation unit that locally irradiates the solid food with near-infrared light, an imaging unit that captures an image of the solid food that has been passed through the near-infrared light, and a detection unit that detects the foreign object from the captured image. (2) The foreign object detection device described in (1), wherein the near-infrared light irradiation unit includes a light source that emits the near-infrared light, and a near-infrared light adjustment unit that adjusts the amount and / or direction of the near-infrared light that is emitted from the light source and passes through the solid food. (3) A foreign object detection device as described in (2), wherein the near-infrared light adjustment unit is arranged between the light source and the solid food and includes a slit that narrows a portion of the light direction of the near-infrared light emitted from the light source. (4) The foreign object detecting device according to (3), wherein the slit has a width in the short direction of 10 mm or less and a length in the long direction of the slit that is equal to or greater than the dimension of the solid food in the long direction. (5) A foreign object detection device described in any one of (1) to (4), comprising a compression and fixing means that applies a compression load to the solid food that is smaller than the crushing compression load that crushes the solid food, thereby compressing and fixing the thickness of the solid food in the direction through which the near-infrared light passes, and the imaging unit captures the image of the compressed solid food through which the near-infrared light passes. (6) The foreign object detecting device according to (5), wherein the compressing and fixing means compresses and fixes the solid food to a thickness of 30% to 90%. (7) The foreign matter detecting device according to any one of (1) to (6), wherein the near-infrared light has a wavelength of 800 nm or more and 1200 nm or less. (8) A foreign object detection device described in any one of (1) to (7), wherein the detection unit detects the foreign object from the images captured by the imaging unit using a machine learning model trained by providing data of defective images of the solid food containing the foreign object and good images of the solid food not containing the foreign object, or a machine learning model trained by providing data of the good images. (9) A foreign object detection device described in any one of (1) to (8), wherein the solid food is meat, seafood, fruit pulp, or potatoes, and the foreign object is one or more selected from the group consisting of bones, shells, seeds, and soft foreign objects. (10) A method for detecting foreign objects mixed into solid food and having a lower near-infrared light transmittance than the solid food, comprising a near-infrared light irradiation process for locally irradiating the solid food with near-infrared light, an imaging process for capturing an image of the solid food through which the near-infrared light has passed, and a foreign object detection process for detecting the foreign object from the captured image. (11) A method for detecting foreign matter comprising a near-infrared light irradiation step of locally irradiating near-infrared light onto a solid food product, an imaging step of capturing an image of the solid food product through which the near-infrared light has passed, a foreign matter detection step of detecting foreign matter having a lower near-infrared light transmittance than the solid food product from the captured image, and a foreign matter removal step of removing the detected foreign matter from the solid food product or removing the solid food product containing the foreign matter. Methods for producing solid foods. [Effects of the Invention]

[0011] The present invention provides a foreign object detection device and a foreign object detection method that can easily detect foreign objects that have a lower near-infrared light transmittance than the solid food and that have been mixed in with the solid food. This device or method can easily detect the foreign objects that have been mixed in with the solid food. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a foreign object detection device according to an embodiment of the present invention. [Figure 2]FIG. 2 is a front view of a near-infrared light adjusting section including a slit of the foreign object detecting device according to the embodiment. [Figure 3] 1 is an image of scallop meat (adductor muscle) photographed in Example 1 (photograph substituting for drawing). [Figure 4] 1 is an image of chicken taken in Example 2 (a photograph substituting for a drawing). [Figure 5] 1 is an image of prune flesh photographed in Example 3 (a photograph substituting a drawing). [Figure 6] 1 is an image of scallop meat (adductor muscle) photographed in Example 4 (photograph substituting a drawing). [Figure 7] 10 is an image of a potato taken in Example 5 (a photograph as a substitute for a drawing). DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will now be described. The present invention relates to a foreign object detection device (hereinafter also referred to as the "foreign object detection device of the present invention") that includes a near-infrared light irradiation unit that locally irradiates near-infrared light onto solid food, an imaging unit that captures an image of the solid food that has transmitted the near-infrared light, and a detection unit that detects foreign objects that have a lower near-infrared light transmittance than the solid food from the captured image.The present invention also includes a foreign object detection method (hereinafter also referred to as the "foreign object detection method of the present invention") that uses the foreign object detection device of the present invention and includes a near-infrared light irradiation step that locally irradiates near-infrared light onto solid food, an imaging step that captures an image of the solid food that has transmitted the near-infrared light, and a foreign object detection step that detects foreign objects from the captured image, as well as a solid food manufacturing method (hereinafter also referred to as the "solid food manufacturing method of the present invention") that further includes a foreign object removal step that removes foreign objects detected by this method or the like from the solid food or removes solid food that contains foreign objects.

[0014] First, an embodiment of a foreign object detection device according to the present invention will be described with reference to Figures 1 and 2. In these drawings, similar components are given the same reference numerals, and duplicate explanations will be omitted where appropriate. Also, for convenience, some parts are not given reference numerals (omitted). Furthermore, the dimensional ratios of the devices and components shown in the drawings may differ from the actual dimensional ratios in order to facilitate understanding of the invention.

[0015] <Overall configuration of foreign object detection device> The foreign object detector 100 according to the present invention is a device for detecting foreign objects 13 that are mixed into solid food 11 (particularly, that are partially or completely buried inside) and have a lower near-infrared light transmittance than the solid food 11. Furthermore, the detection of such foreign objects 13 can also be performed in-line.

[0016] The target solid food 11 is a food that is solid at room temperature (10°C to 35°C), and typical examples include meat (chicken, pork, beef, etc.), seafood (fish meat, cephalopod meat such as squid and octopus, shelled seafood such as scallops, sea urchins, shrimp, and crabs), fruit pulp (edible fruit pulp such as prunes and berries, which may include the edible skin), and potatoes (potatoes, sweet potatoes, taro, etc.). These may be fresh (including frozen and thawed) or processed (boiled, blanched, dried, etc.). The foreign object detector 100 according to the present invention is particularly suited to soft solid foods, i.e., solid foods 11 that can be compressed without crushing to between 30% and 90% of their thickness in at least one direction by applying a compressive load smaller than the crushing compressive load, as described below. All of the above examples are soft solid foods that can be compressed without crushing to 30% to 90% of their thickness in at least one direction. However, solid food 11 does not include foods that are liquid or paste-like at room temperature. The foreign object detection device 100 of the present invention is extremely effective in detecting bones in livestock meat, bones and scales in fish meat, shells in the flesh (meat, etc.) of shelled seafood, seeds in fruit pulp, or soft foreign objects in potatoes.

[0017] Furthermore, foreign matter 13 having a lower near-infrared light transmittance than the target solid food 11 is less susceptible to near-infrared light 23 than this solid food 11 and is undesirable or should be prevented from being mixed in when this solid food 11 is made into a finished product, and examples of such foreign matter include bones (including small bones and cartilage), scales, shells (including shells and sea urchin spines), seeds (hard seeds, etc.), and soft foreign matter (stems (the stems connecting the fruit to the branches), roots, stalks, soft fibrous materials used in manufacturing operations, etc.), and some of these (for example, bone fragments, scale fragments, shell fragments, seed fragments, stem fragments, etc.) are also included. These substances are difficult to detect with X-ray machines or metal detectors because they are mainly derived from living organisms and often have a small difference in density with the target solid food 11, and are non-metallic, and are particularly difficult to detect when partly or wholly buried inside the solid food 11. However, because these substances often have a lower near-infrared light transmittance than the solid food 11 and the difference is large, the foreign object detection device 100 of the present invention is characterized in that it can easily detect one or more selected from the group consisting of these substances that have become mixed into the solid food 11. In addition to these, any substance that has a lower near-infrared light transmittance than the target solid food 11 and whose mixing into the solid food 11 is undesirable or should be prevented when the solid food 11 is made into a finished product can be detected as foreign object 13.

[0018] The foreign object detector 100 according to the present invention includes at least a near-infrared light irradiator 20, an image capturer 41, and a detector 51 (see, for example, FIG. 1). Alternatively, the foreign object detector 100 may further include a controller 61, a compressing and fixing unit 71, a conveying unit 73, and the like, as shown in FIG. 1. These will be described in detail below.

[0019] <Near infrared light irradiation section> The near-infrared light irradiating unit 20 is a device capable of locally irradiating the solid food 11 with near-infrared light 23. Therefore, it includes at least a light source 21 that emits the near-infrared light 23. Here, "locally irradiating" near-infrared light 23 includes not only irradiating only a portion of solid food 11 with near-infrared light 23, but also irradiating the entire solid food 11 with weak near-infrared light 23 and irradiating a portion with stronger near-infrared light 23. Furthermore, "near-infrared light" refers to infrared light (light with a wavelength longer than that of visible light) with a wavelength of 780 nm or more and 2500 nm or less, which is closer to visible light. Light source 21 is not limited as long as it can emit such near-infrared light, and examples thereof include an LED light (such as UPD2450W-2S manufactured by U-Technology) and a halogen light (such as LA-100IR manufactured by Hayashi Repic).

[0020] Examples of embodiments for locally irradiating near-infrared light 23 include an embodiment in which light source 21 itself locally emits near-infrared light 23, and an embodiment in which near-infrared light 23 emitted from light source 21 is partially blocked by a shield or the like, or the light direction is partially focused or aligned by a mirror, polarizing plate, etc. This makes it possible to suppress scattering of near-infrared light 23 inside solid food 11, etc., and therefore makes it easier to capture a clear image of foreign object 13 even if foreign object 13 is buried inside solid food 11, making it possible to easily detect foreign object 13. Furthermore, in the foreign object detection device 100 of the present invention, an embodiment in which the near-infrared light irradiation unit 20 includes a light source 21 that emits near-infrared light 23 and a near-infrared light adjustment unit 31 (for example, the aforementioned shield, mirror, polarizing plate, etc.) that adjusts the amount and / or direction of the near-infrared light 23 that is emitted from the light source 21 and passes through the solid food 11 is more preferable because this makes it easier to design the device, allows the device to be obtained at low cost, and also makes it easier to detect foreign objects 13.

[0021] In particular, it is more preferable that the near-infrared light adjustment unit 31 includes, as a shielding member for blocking a portion of the near-infrared light 23, a slit 31a, as shown in Fig. 2, disposed between the light source 21 and the solid food 11, for narrowing a portion of the light direction of the near-infrared light 23 emitted from the light source 21. That is, it is more preferable that the near-infrared light 23 (emitted light 23a) emitted from the light source 21 passes through the slit 31a of the near-infrared light adjustment unit 31, thereby narrowing at least a portion of the light direction, and that the near-infrared light 23 that has passed through the slit 31a is transmitted through the solid food 11 (transmitted light 23b). In other words, it is more preferable that the near-infrared light adjustment unit 31 includes a member in which the slit 31a is formed, thereby narrowing a portion of the light direction of the near-infrared light 23 emitted from the light source 21. This is because scattering of near-infrared light 23 inside solid food 11 can be easily suppressed regardless of the type of device of light source 21, and therefore even if the light intensity is set to a stronger level, the image is less likely to turn white and the foreign matter 13 becomes indistinguishable, making it easier to detect the foreign matter 13.

[0022] For example, the near-infrared light adjustment unit 31 may be a member such as a plate-like structure made of a material capable of blocking near-infrared light 23, with a slit 31a, which is a rectangular cutout, formed in a part of the plate (FIG. 2). Examples of materials capable of blocking near-infrared light 23 include metal, wood, colored resin, and paper. The shape of the slit 31a is not limited to a rectangular shape, and may be an elliptical shape, for example.

[0023] From the viewpoint of suppressing scattering of near-infrared light 23, it is preferable that the width D (maximum width) of the slit 31a in the short side direction is 10 mm or less, more preferably 8 mm or less, and even more preferably 5 mm or less, and that the length L in the long side direction is equal to or greater than the dimension of solid food 11 in the long side direction. From the viewpoint of easily obtaining the amount of light necessary to detect foreign matter 13, it is more preferable that the minimum width of the slit 31a in the short side direction is 0.5 mm or more, and even more preferably 1 mm or more.

[0024] Furthermore, although not limited to this, by the configuration of the slit 31a described above, when the near-infrared light irradiating unit 20 and the solid food 11 are both stationary, the surface area of ​​the region on the solid food 11 where the near-infrared light 23 is locally irradiated may be preferably 20% or less of the total surface area of ​​the solid food 11, more preferably 17% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0025] When the near-infrared light adjusting unit 31 includes the above-described slit 31a, in order to more reliably detect foreign matter 13 mixed in solid food 11, it is preferable to move solid food 11 or slit 31a so that slit 31a moves in a constant direction and at a constant speed relative to solid food 11, and continuously capture images of solid food 11 during this movement. It is then preferable to combine these continuously captured images and use them as an image for detecting foreign matter 13.

[0026] In addition, if the light source 21 itself is configured to be capable of locally emitting near-infrared light 23 as described above (such as a light source 21 capable of emitting near-infrared laser light), the near-infrared light irradiating unit 20 may be an embodiment that does not include the near-infrared light adjusting unit 31 described above.

[0027] Furthermore, since this makes it easier to detect the types of foreign matter 13 described above, it is preferable that the near-infrared light 23 locally irradiated onto the solid food 11 from the near-infrared light irradiator 20, i.e., the near-infrared light 23 that passes through the solid food 11, has a wavelength of 800 nm or more and 1200 nm or less. The lower limit of this wavelength is more preferably 900 nm or more, and even more preferably 950 nm or more. The upper limit of this wavelength is also more preferably 1100 nm or less, and even more preferably 1050 nm or less.

[0028] <Image capture unit> The imaging unit 41 is a device capable of capturing an image of the solid food 11 through which the near-infrared light 23 has passed (an image of the solid food 11 including the transmitted light 23b), and is exemplified by an image capturing camera, for example. The imaging unit 41 may be configured to capture the above-described image, and its location is not particularly limited, for example, in a configuration including a mirror together with the image capturing camera. However, from the viewpoint of ease of designing the device, it is preferable that the imaging unit 41 be located at a position facing the near-infrared light irradiator 20 (on the opposite side) with respect to the solid food 11.

[0029] The image capturing camera is not limited to, but is preferably, a camera with high sensitivity in the near-infrared wavelength region, such as an InGaAs camera equipped with an InGaAs (indium gallium arsenide) sensor, a black silicon camera that is cheaper than other cameras and can also capture images in the visible light region, or a hyperspectral camera that can scan multiple wavelengths. The exposure time (shutter speed) of the camera when capturing one image can be set depending on the amount of near-infrared light 23 that passes through the solid food 11, and is, for example, not limited to, about 1,000 μs or more and 150,000 μs or less.

[0030] <Detection section> The detection unit 51 is a device capable of detecting foreign matter 13 from an image captured by the imaging unit 41, and is preferably a computer. Therefore, for example, the detection unit 51 may be a computer including a storage device 51a and a processing unit 51b connected via a network or the like. If necessary, the detection unit 51 may also include an input unit such as a keyboard, mouse, or touch panel for inputting settings, and a monitor for displaying captured images. From the perspective of improving the accuracy of detecting foreign matter 13, the detection unit 51 is preferably connected to a control unit 61 (e.g., a control computer) that controls at least some of the devices included in the foreign matter detection device 100 according to the present invention, such as the light source 21 and the imaging unit 41, and is controlled in conjunction with the emission of near-infrared light 23 from the light source 21 and the timing of imaging by the imaging unit 41.

[0031] In this detection unit 51, the image captured by the imaging unit 41 is read into a storage device 51a or the like, and multiple images are combined, if necessary, to generate image data. Then, in an arithmetic processing device 51b or the like, the presence or absence of foreign matter 13 is determined from this image data based on the intensity (brightness) of transmitted light 23b, and if foreign matter 13 is present, its position is also identified. The results are then output to a monitor or other device.

[0032] Furthermore, the detection unit 51 (e.g., the arithmetic processing device 51b) is preferably configured to detect the foreign matter 13 by a configuration in which the presence or absence of the foreign matter 13 is determined by a machine learning model trained on data (teaching data) from images captured by the imaging unit 41, including defective images of solid food 11 containing the foreign matter 13 and non-defective images of solid food 11 not containing the foreign matter 13, or by a configuration in which the machine learning model is trained on data (teaching data) from among these, including only non-defective images, and determines solid food 11 that does not meet the score or the like as containing the foreign matter 13 (defective). In other words, it is preferable to detect the foreign matter 13 by a machine learning model trained on data including at least non-defective images. This is because this can speed up foreign matter detection and also improves the accuracy of foreign matter detection.

[0033] This machine learning (ML) model is also called a trained model or an AI (Artificial Intelligence) model, and is a model obtained by machine learning using training data, i.e., supervised learning. For example, but not limited to, it may be a regression formula obtained by regression analysis, or may be composed of a convolutional neural network including a deep neural network, and may be realized by a combination of a computer program and parameters, a combination of multiple functions and parameters, etc. In addition, a method other than the machine learning model may be used, such as setting a brightness threshold for identifying foreign matter 13 in an image in advance and storing it in the storage means of the detection unit 51, and the detection unit 51 determining whether or not a foreign matter 13 is present by comparing this threshold with the threshold.

[0034] <Compression fixing means> Furthermore, the foreign object detecting device 100 according to the present invention preferably includes a compressing and fixing means 71 that applies a compressive load to the solid food 11 that is smaller than the crushing compression load that crushes the solid food 11, thereby compressing and fixing the thickness of the solid food 11 in the direction through which near-infrared light 23 is transmitted (at least one direction if there are multiple transmission directions). In this case, the imaging unit 41 captures an image of the solid food 11 compressed by the compressing and fixing means 71 and transmitting near-infrared light 23. Therefore, in this configuration, it is important to fix the solid food 11 using a tool or the like so that the thickness of the solid food 11 does not return to its original state. It is also important to compress the solid food 11 to a degree that will not cause it to fracture, and to maintain that state. With this configuration, scattering of the transmitted near-infrared light 23 (particularly scattering of near-infrared light 23 at the periphery of the foreign object 13 that does not directly hit the foreign object 13) can be further suppressed due to the effects of reducing the distance between the foreign object 13 inside the solid food 11 and the surface of the solid food 11 in the direction through which the near-infrared light 23 passes and reducing the amount of unevenness on the surface of the solid food 11.On the other hand, the near-infrared light transmittance of areas of the solid food 11 that do not contain the foreign object 13 is further increased, thereby allowing a clearer image of the foreign object 13 to be obtained and making the foreign object 13 easier to detect.

[0035] The compressing and fixing means 71 is preferably configured to compress and fix the thickness of the solid food 11 in the direction through which the near-infrared light 23 is transmitted to 30% to 90% by a compression load smaller than the crushing compression load, from the viewpoint of both maintaining the shape of the solid food 11 and facilitating detection of foreign matter 13. Therefore, in a configuration including such a compressing and fixing means 71, it is preferable to use the soft solid food described above, which can be compressed and fixed without crushing to 30% to 90% of its thickness in the direction through which the near-infrared light 23 is transmitted. The lower limit of this compression is preferably 33% or more, more preferably 40% or more, and even more preferably 50% or more. The upper limit is more preferably 85% or less, even more preferably 80% or less, and even more preferably 75% or less. For example, in the case of prune pulp, it is preferable to compress a thickness of approximately 16 to 25 mm to a thickness of approximately 10 to 15 mm, which falls within the above range. Here, the percentage of compression indicates the thickness after compression expressed as a percentage (%), assuming that the thickness of the solid food 11 in the direction through which the near-infrared light 23 passes before compression is 100%.

[0036] The specific configuration of this compression fixing means 71 is not limited to, but may be exemplified by an embodiment in which the solid food 11 is fixed by being sandwiched from both sides in the direction that transmits the near-infrared light 23 using a plate-like member (such as a plate made of acrylic resin or glass) that is capable of transmitting the near-infrared light 23.

[0037] <Transportation means> Furthermore, the foreign object detecting device 100 according to the present invention preferably includes a conveying means 73 capable of conveying the target solid food 11 (such as soft solid food compressed and fixed by the compressing and fixing means 71 described above) to a process in which near-infrared light 23 is transmitted, and then further conveying the food from this process to the next process. This conveying means 73 may be, for example, a belt conveyor with a drive mechanism as shown in FIG. 1, but must be configured so as not to interfere with the irradiation of the conveyed solid food 11 with near-infrared light 23 and the imaging thereof (such as a conveyor that is transparent to near-infrared light, a conveyor with a gap in the near-infrared light irradiation area, etc.). Furthermore, this conveying means 73 is preferably connected to the control unit 61 described above so that the conveying speed, etc., can be controlled.

[0038] When the foreign object detector 100 according to the present invention is equipped with such a conveying means 73, it is preferable that the near-infrared light irradiator 20 (the light source 21 and the near-infrared light adjuster 31 including the slit 31a) and the image capturer 41 are fixedly arranged, as shown in FIG. 1, and that the image capturer 41 captures images at predetermined time intervals while the conveying means 73 moves the solid food 11 at a constant conveying speed. In this case, the direction of movement (conveyance direction) coincides with the width direction of the slit 31a, as indicated by the black arrow in FIG. 1, for example. With this configuration, images of the solid food 11 that has been irradiated with near-infrared light 23 can be continuously captured, and the resulting images can be processed by the detector 51, facilitating detection of foreign objects 13 regardless of their position in the solid food 11.

[0039] Furthermore, in this configuration, when the near-infrared light irradiator 20 includes a slit 31a as the near-infrared light adjuster 31, it is preferable that the distance the solid food 11 is conveyed by the conveying means 73 during the imaging time interval, i.e., the length of movement of the slit 31a for each captured image, is smaller than the width D of the slit 31a. This is because at least one image of every portion of the solid food 11 can be captured as it passes through the slit 31a. The conveying means 73 may move the solid food 11 continuously without stopping, or may move intermittently by repeatedly moving and stopping. When moving intermittently, it is preferable that the control unit 61 control the operation of the conveying means 73 and the imaging unit 41 so that the imaging unit 41 captures images while the solid food 11 is stopped. This allows the imaging unit 41 to capture images with minimal blur. Furthermore, when the conveying means 73 moves the solid food 11 intermittently, it is preferable that the length of each movement (conveyance distance) be smaller than the width D of the slit 31a, as described above.

[0040] In the above embodiment, the image capturing unit 41 captures images while the transport means 73 transports the solid food 11, but the present invention is not limited to this. For example, the light source 21 may be provided with a drive mechanism (not shown) that changes the irradiation direction of the near-infrared light 23, and the image capturing unit 41 may capture images while sequentially changing the position at which the near-infrared light 23 is irradiated onto the stationary solid food 11, or the image capturing unit 41 may capture images while sequentially changing the position of the near-infrared light adjusting unit 31 (for example, a member including a slit 31a) between the fixedly disposed light source 21 and the stationary solid food 11.

[0041] Furthermore, the foreign object detection device 100 according to the present invention may include any other devices or components than those described above, provided that the effects of the present invention are not affected. For example, the device may be equipped with a rejection mechanism (air, a rejection conveyor, etc.) that rejects solid food 11 containing foreign objects 13 based on the captured image, or with auxiliary lighting other than light source 21 that can improve the accuracy of image capture.

[0042] <Foreign object detection method, etc.> Next, an embodiment of a foreign object detection method and the like according to the present invention will be described.

[0043] The foreign object detection method according to the present invention can be implemented using the foreign object detection device 100 according to the present invention, and includes a near-infrared light irradiation step of locally irradiating near-infrared light 23 onto solid food 11, an imaging step of capturing an image of solid food 11 that has been irradiated with the near-infrared light 23, and a foreign object detection step of detecting foreign objects 13 from the captured image. The details of each step may be the same as those of the foreign object detection device 100 according to the present invention described above.

[0044] Furthermore, the foreign object detection method according to the present invention may include a compressing and fixing step using a compressing and fixing means that applies a compressive load smaller than the crushing compressive load to the solid food 11 to compress and fix the thickness of the solid food 11 in the direction through which the near-infrared light 23 is transmitted. The method may also include a conveying step in which the solid food 11 is conveyed by a conveying means. These steps may be similar in configuration to the foreign object detection device 100 according to the present invention described above. For example, the method may involve moving the solid food 11 compressed and fixed by the compressing and fixing means 71 at a constant conveying speed by the conveying means 73 (compressing and fixing step, conveying step), locally irradiating the compressed solid food 11 with near-infrared light 23 by the near-infrared light irradiating unit 20 (near-infrared light irradiation step), capturing images of the solid food 11 through which the near-infrared light 23 has transmitted by the imaging unit 41 at predetermined time intervals (imaging step), and detecting foreign object 13 using a composite of the captured images by the detection unit 51 (foreign object detection step).

[0045] The foreign object detector 100 according to the present invention or the foreign object detection method according to the present invention can efficiently detect foreign objects 13 such as bones, shells, seeds, stems, and roots that are difficult to detect with X-ray inspection machines or metal detectors, particularly foreign objects 13 buried inside the solid food 11 (which are difficult or impossible to see from the outside). Furthermore, by combining the steps of the foreign object detection method according to the present invention with a foreign object removal step of removing detected foreign objects 13 from the solid food 11 or removing solid food 11 containing foreign objects 13 from the manufacturing process, a solid food manufacturing method according to the present invention can be provided that can manufacture solid food 11 free of the above-described foreign objects 13. For example, a method for manufacturing solid food 11 can be provided that includes the near-infrared light irradiation step, imaging step, and foreign object detection step described above, followed by the foreign object removal step described above. This manufacturing method may further include the compressing and fixing step and the conveying step described above.

[0046] Examples of the foreign matter removal step include a step of sucking out foreign matter 13 contained in solid food 11 using a robot or the like, and a rejection step of mechanically rejecting (sorting) solid food 11 containing foreign matter 13 from the manufacturing process using a defective product rejection device (sorting mechanism, etc.). Furthermore, this foreign matter removal step may include a step of manually removing foreign matter 13 from solid food 11 rejected from the manufacturing process and returning solid food 11 from which foreign matter 13 has been removed to the manufacturing process.

[0047] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples, and various modifications are possible within the technical concept of the present invention. [Example]

[0048] Example 1 Boiled oyster adductor muscles (10mm or 15mm thick) containing shell fragments as foreign matter were irradiated with near-infrared light at a wavelength of 1050nm using an LED light (UPD2450W-2S, manufactured by U-Technology Co., Ltd.), and images of the adductor muscles that had been exposed to near-infrared light were taken using an InGaAs camera (XEVA-165 SS-1700, manufactured by Xenix Corporation, resolution 300 x 256 pixels) under the following conditions.

[0049] The adductor muscle was left in its original state (10 mm thick), and near-infrared light was irradiated onto the entire body so that it penetrated in the thickness direction (no compression, no slits). Images were taken with a camera exposure time of 6000 μs. The adductor muscle was left in its original state (10mm or 15mm thick), and near-infrared light was locally irradiated through a 5mm or 1mm slit in the short direction formed in a metal plate so that it could be transmitted in the thickness direction (no compression x 5mm slit, no compression x 1mm slit). Images were taken with a camera exposure time of 20,000μs or 80,000μs. <c>A scallop adductor muscle (10 mm thick) was sandwiched between acrylic plates and compressed (compressed without crushing) to a thickness of 6 mm, and fixed in place. Near-infrared light was then locally irradiated through a 5 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (6 mm compression x 5 mm slit). Images were taken with a camera exposure time of 10,000 μs. <d>A scallop (15mm thick) was sandwiched between acrylic plates and compressed (compressed without crushing) to a thickness of 12mm, and fixed in place. Near-infrared light was then locally irradiated through a 1mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (12mm compression x 1mm slit). Images were taken with a camera exposure time of 80,000μs.

[0050] The images obtained are shown in Figure 3. The leftmost part of Figure 3 is< / d> < / c> The image, the two images at the top and bottom of the center The image on the right is <c>The bottom right corner is the image of <d>It should be noted that all of the images under the condition using the slit were taken continuously while moving the metal plate on which the slit was formed so that the slit moved from left to right in the image of FIG. 3, and these images were synthesized (the images under the condition using the slit in the following examples were also taken in a similar manner unless otherwise specified).

[0051] From this result, we can see that near-infrared light was irradiated onto the entire surface without a slit and transmitted through it.< / d> < / c> In the previous example, it was difficult to detect shell fragments, but by using a slit, near-infrared light was irradiated locally and allowed to pass through. Furthermore, after compressing and fixing the adductor muscle to 60% or 80% of its original thickness, near-infrared light was irradiated locally through a slit and transmitted through the muscle. <c>and <d>In this case, the shell fragments were clearer and easier to detect.

[0052] Example 2 Chicken meat (raw chicken fillet, 24mm or 20mm thick) containing bone (cartilage or hard bone) as a foreign body was irradiated with near-infrared light at a wavelength of 1050nm using an LED light (U-Technology, UPD2450W-2S). Images of the chicken meat that had been exposed to near-infrared light were then taken using an InGaAs camera (Xenix, XEVA-165 SS-1700, resolution 300 x 256 pixels) under the following conditions.

[0053] <e>The chicken meat was left in its original state (24mm or 20mm thick), and near-infrared light was irradiated onto the entire surface so that it penetrated in the thickness direction (no compression, no slits). <f>Chicken meat (20 mm thick) was sandwiched between acrylic plates and compressed (compressed without crushing) to a thickness of 15 mm or 12 mm, and near-infrared light was irradiated over the entire surface so that it penetrated in the direction of compression (15 mm or 12 mm compression, no slits). <g>Chicken meat (24 mm thick) was sandwiched between acrylic plates and compressed (compressed without crushing) to a thickness of 8 mm, and then near-infrared light was locally irradiated through a 1 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (8 mm compression x 1 mm slit). <h>Chicken meat (20 mm thick) was sandwiched between acrylic plates and compressed (compressed without crushing) to a thickness of 15 mm or 12 mm, and then near-infrared light was locally irradiated through a 1 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (15 mm compression or 12 mm compression x 1 mm slit).

[0054] The images obtained are shown in Figure 4. The top and bottom left corners of Figure 4 are <e>The image and the two images in the bottom center are <f>The image on the right is <g>The image and the two images on the bottom right are <h>From this result, it is clear that near-infrared light was irradiated onto the entire surface without slits or compression and transmitted through the glass. <e>and near-infrared light was irradiated onto the entire surface with compression but no slits. <f>In the previous study, bones were difficult to detect, but after compressing and fixing the specimen until the thickness was 33.3%, near-infrared light was irradiated locally through a slit. <g>After compressing and fixing the material until the thickness was 75% or 60%, near-infrared light was locally irradiated through a slit. <h>So obviously bones ( <g>is cartilage, <h>It was easier to detect bones (both indicated by circles in the images). Although not shown in the image, even when near-infrared light was locally irradiated and passed through a 1 mm slit without compression, <e>or <f>The bones were easier to detect.

[0055] Example 3 Prune pulp (dried, 18mm, 17mm, or 20mm thick) containing seed fragments as foreign matter was irradiated with near-infrared light at a wavelength of 1050nm using an LED light (U-Technology, UPD2450W-2S), and the pulp that was transmitted through this near-infrared light was imaged with an InGaAs camera (Xenix, XEVA-165 SS-1700, resolution 300 x 256 pixels) under the following conditions, with the pulp, light source, slit, and camera all fixed and with a camera exposure time of 5000μs. Note that compression under the following conditions did not crush the pulp.

[0056] Near-infrared light was irradiated so that it penetrated in the thickness direction (compression direction) under four conditions: 18mm thick fruit pulp was left as is (no compression), compressed and fixed to a thickness of 14mm (14mm adjustment), compressed and fixed to a thickness of 12mm (12mm adjustment), and compressed and fixed to a thickness of 12mm with a 10mm wide slit formed in a paper plate (12mm adjustment + slit). <k>Near-infrared light was irradiated so that it penetrated in the thickness direction (compression direction) under four conditions: 17mm thick fruit pulp was left as is (no compression), compressed and fixed to a thickness of 14mm (14mm adjustment), compressed and fixed to a thickness of 12mm (12mm adjustment), and compressed and fixed to a thickness of 12mm with a 10mm wide slit formed in a paper plate (12mm adjustment + slit). <l>Near-infrared light was irradiated so that it penetrated in the thickness direction (compression direction) under four conditions: 20 mm thick fruit pulp was left as is (no compression), compressed and fixed to a thickness of 14 mm (adjusted by 14 mm), compressed and fixed to a thickness of 12 mm (adjusted by 12 mm), and compressed and fixed to a thickness of 12 mm with a 10 mm wide slit formed in a paper plate (adjusted by 12 mm + slit).

[0057] The images obtained are shown in Figure 5. The top four images in Figure 5 are The image, the middle 4 images <k>The image and the bottom four images are <l>These results show that for prune pulp of any thickness, compressing and fixing it to a thickness of 12 mm (60.0-70.6%), passing it through a slit and locally irradiating it with near-infrared light, made the seed fragments clearer and easier to detect.

[0058] Example 4 A scallop adductor muscle (boiled, 10 mm thick) containing shell fragments and sea urchin spines as foreign matter was irradiated with near-infrared light at a wavelength of 1050 nm using an LED light (U-Technology, UPD2450W-2S), and the adductor muscle that had been exposed to this near-infrared light was photographed using an InGaAs camera (Xenix, XEVA-165 SS-1700, resolution 300 x 256 pixels) under the following conditions. Note that the compression conditions below were all performed without crushing the material.

[0059] <m>The adductor muscle was left in its original state (10 mm thick) and near-infrared light was irradiated onto the entire body so that it would penetrate in the thickness direction (no compression, no slits), or near-infrared light was irradiated locally through a 1 mm slit in the short direction formed in a metal plate so that it would penetrate in the thickness direction (no compression x 1 mm slit). <n>A scallop adductor muscle (10 mm thick) was sandwiched between acrylic plates and compressed to a thickness of 9 mm, and fixed in place. Near-infrared light was then locally irradiated through a 5 mm or 1 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (compressed to 9 mm x 5 mm slit, compressed to 9 mm x 1 mm slit). A scallop adductor muscle (10 mm thick) was sandwiched between acrylic plates and compressed to a thickness of 8 mm, and fixed in place. Near-infrared light was then locally irradiated through a 5 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (compressed to 8 mm x 5 mm slit). <q>A scallop adductor muscle (10 mm thick) was sandwiched between acrylic plates and compressed to a thickness of 7 mm, and fixed in place. Near-infrared light was then locally irradiated through a 5 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (compressed to 7 mm x 5 mm slit). <r>A scallop adductor muscle (10 mm thick) was sandwiched between acrylic plates and compressed to a thickness of 6 mm, and fixed in place. Near-infrared light was then locally irradiated through a 5 mm or 1 mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (compressed to 6 mm x 5 mm slit, compressed to 6 mm x 1 mm slit).

[0060] The images obtained are shown in Figure 6. Starting from the left column of Figure 6, <m>Images of, <n> Images of,< / n> < / m> < / r> < / q> Images of, <q>Images of, <r>As a result, near-infrared light was irradiated onto the entire surface without slits or compression, and the light was transmitted through the entire surface. <m>In the top image, foreign objects (shell fragments and sea urchin spines) could only be detected in the areas exposed from the adductor muscle. However, by using a 1 mm slit to locally irradiate and transmit near-infrared light, the entire foreign object could be detected ( <m>(The circle in the bottom image) By compressing and fixing the sample until the thickness was 90% or less, and then irradiating the sample locally with near-infrared light through a slit, it was clearly easier to detect the entire foreign object ( <n> 、< / n> < / m> < / m> < / r> < / q> 、 <q>、 <r>(Inside the circles in each image).

[0061] Example 5 Potatoes containing fiber strings as foreign matter (heat-treated at 90°C for 15 minutes, 19 mm thick) were irradiated with near-infrared light at a wavelength of 1050 nm using an LED light (UPD2450W-2S, manufactured by U-Technology), and images of the potatoes that were allowed to pass through this near-infrared light were taken using an InGaAs camera (XEVA-165 SS-1700, manufactured by Xenix, resolution 300 x 256 pixels) under the following conditions. Note that the compression under the following conditions did not involve crushing.

[0062] <s>The potato was left as it was (thickness 19 mm), and near-infrared light was irradiated onto the entire surface so that it penetrated in the thickness direction (no slits or compression). Images were taken with a camera exposure time of 10,000 μs or 20,000 μs. <t>The potato was left as is (thickness 19 mm), and near-infrared light was locally irradiated through a 5 mm slit in the short direction formed in a metal plate so that it could be transmitted in the thickness direction (slit present, no compression). The image was taken with a camera exposure time of 60,000 μs. A potato (19mm thick) was sandwiched between acrylic plates and compressed to a thickness of 15mm, 13mm, or 12mm, and fixed in place. Near-infrared light was then locally irradiated through a 5mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (with slit and compression). Images were taken with a camera exposure time of 50,000μs. <v>A potato (19mm thick) was sandwiched between acrylic plates and compressed to a thickness of 13mm or 12mm, and fixed in place. Near-infrared light was then locally irradiated through a 1mm slit in the short direction formed in the metal plate so that it could be transmitted in the direction of compression (with slit and compression). Images were taken with a camera exposure time of 120,000μs.

[0063] The images obtained are shown in Figure 7. The two images on the left side of Figure 7 are <s>The image in the upper center of Figure 7 is <t>The image in the lower center of Figure 7 is The two images on the right side of Figure 7 are <v>As a result, near-infrared light was irradiated onto the entire surface without slits or compression, and the light was transmitted through the entire surface. <s>It was difficult to detect foreign matter in the images, but by adding slits or compressing and fixing the potato until the thickness was 63.2-78.9% and then irradiating and transmitting near-infrared light locally with slits, it was clearly easier to detect foreign matter (the strings mixed in slightly to the left of the center of the potato in each image). <t> 、 、 <v>(Image of).

[0064] Example 6 As defective products, 10 samples were prepared for learning and 50 samples were prepared for testing, with 5mm x 5mm seed fragments (foreign matter) embedded in the center of the dried prune pulp. 10 samples were prepared for learning and 50 samples were prepared for testing, with 50 samples of non-defective prune pulp without seed fragments.

[0065] These were then irradiated with near-infrared light at a wavelength of 1050 nm using an LED light (UPD2450W-2S, manufactured by U-Technology). In the conventional method (control method), the near-infrared light was irradiated entirely and transmitted, and images were taken with an InGaAs camera (XEVA-165 SS-1700, manufactured by Xenix, resolution 300 x 256 pixels). In the improved method (method of the present invention), near-infrared light passed through a slit (10 mm wide) was irradiated locally and transmitted, and images were taken with an InGaAs camera (XEVA-165 SS-1700, manufactured by Xenix, resolution 300 x 256 pixels), with the flesh, light source, slit, and camera all fixed, as in Example 3. The conditions for these measurements are shown in Table 1 below.

[0066] [Table 1]

[0067] Of the images obtained, 50 images, including 25 images of defective products and 25 images of non-defective products, were visually inspected for the presence or absence of foreign matter by five inspectors. These inspectors had previously reviewed the images of the training samples (images of defective products and images of non-defective products) and had trained to distinguish between them. The results are shown in Table 2 below. These results demonstrate that the method of the present invention had a 30% or higher accuracy rate compared to the control method, making it easier to detect seed fragments mixed into prune pulp. Furthermore, it is expected that the accuracy rate will be further improved if a machine learning model trained using such images of defective products and non-defective products as training data is used, and it is recognized that even smaller seed fragments can be detected.

[0068] [Table 2] [Explanation of symbols]

[0069] 100 Foreign object detection device 11 Solid Foods 13 Foreign object 20 Near-infrared light irradiation section 21 Light source 23 Near-infrared light 23a Synchrotron radiation 23b Transmitted light 31 Near-infrared light adjustment section 31a Slit 41 Imaging unit 51 Detection unit 51a Storage device 51b Processing unit 61 Control Unit 71 Compression fixing means 73 Means of transport D Width of the slit in the short direction L: longitudinal length of the slit< / v> < / t> < / s> < / v> < / t> < / s> < / v> < / t> < / s> < / r> < / q> < / n> < / m> < / l> < / k> < / l> < / k> < / f> < / e> < / h> < / g> < / h> < / g> < / f> < / e> < / h> < / g> < / f> < / e> < / h> < / g> < / f> < / e> < / d> < / c>

Claims

1. A foreign object detection device that detects foreign objects mixed in solid food and having a near-infrared light transmittance lower than that of the solid food, a compressing and fixing means for applying a compressive load to the solid food that is smaller than a crushing compressive load that crushes the solid food, thereby compressing and fixing the thickness of the solid food in a direction through which near-infrared light is transmitted; a near-infrared light irradiator that locally irradiates the compressed solid food with near-infrared light; an imaging unit that captures an image of the compressed solid food by transmitting the near-infrared light; a detection unit that detects the foreign matter from the captured image, Foreign object detection device.

2. 2. The foreign object detection device according to claim 1, wherein the near-infrared light irradiator comprises: a light source that radiates the near-infrared light; and a near-infrared light adjuster that adjusts the amount and / or direction of the near-infrared light that is radiated from the light source and passes through the solid food.

3. 3. The foreign object detecting device according to claim 2, wherein the near-infrared light adjusting unit includes a slit disposed between the light source and the solid food and configured to narrow a portion of the light direction of the near-infrared light emitted from the light source.

4. 4. The foreign object detecting device according to claim 1, wherein the near-infrared light has a wavelength of 800 nm or more and 1200 nm or less.

5. The foreign object detection device according to any one of claims 1 to 4, wherein the detection unit detects the foreign object from the images captured by the imaging unit using a machine learning model trained by providing data of defective images of the solid food containing the foreign object and good images of the solid food not containing the foreign object, or a machine learning model trained by providing data of the good product images.

6. A foreign object detection device as described in any one of claims 1 to 5, wherein the solid food is either livestock meat, seafood meat, fruit pulp, or potatoes, and the foreign object is one or more selected from the group consisting of bones, shells, seeds, and soft foreign objects.

7. A method for detecting a foreign object mixed in a solid food and having a near-infrared light transmittance lower than that of the solid food, comprising: a compressing and fixing step using a compressing and fixing means that applies a compressive load to the solid food that is smaller than a crushing compressive load that is a compressive load at which the solid food is crushed, thereby compressing and fixing the thickness of the solid food in a direction through which near-infrared light is transmitted; a near-infrared light irradiation step of locally irradiating the compressed solid food with near-infrared light; an imaging step of capturing an image of the compressed solid food by transmitting the near-infrared light; a foreign object detection step of detecting the foreign object from the captured image. Foreign object detection methods.

8. A compressive fixing step using a compressive fixing means that applies a compressive load to the solid food that is smaller than the crushing compressive load that crushes the solid food, thereby compressing and fixing the thickness of the solid food in a direction that transmits near-infrared light; a near-infrared light irradiation step of locally irradiating the compressed solid food with near-infrared light; an imaging step of capturing an image of the compressed solid food by transmitting the near-infrared light; a foreign object detection step of detecting a foreign object having a lower near-infrared light transmittance than the solid food from the captured image; a foreign matter removal step of removing the detected foreign matter from the solid food or removing the solid food containing the foreign matter. Methods for producing solid foods.

Images