JP2009115613A - Foreign matter inspecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foreign matter inspecting apparatus capable of speedily and precisely detecting a foreign matter mixed in a sample, especially in food in the process of producing and testing the food. <P>SOLUTION: The foreign matter inspecting apparatus includes a feeding means for feeding samples continuously, a stroboscopic light source, a reflecting plate for reflecting light from the stroboscopic light source and irradiating the front and rear face of the sample indirectly, and a photographing means for photographing the samples in synchronization with the light emission of the stroboscopic light source. The photographing means photographs the sample so as to split the wavelength band of the reflection light from the sample into two or more portions, and creates an image by combining respective images or differential images, thereby highlighting the foreign matter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for foreign matters mixed in a process of manufacturing and inspecting a sample, and more particularly, a foreign substance inspection apparatus that enables high-speed and high-precision detection of foreign substances mixed in food during the manufacture and inspection of food. About.

  There are cases in which foreign substances such as metals, stones, glass, hair, insects and the like are mixed in the production process and inspection process of a sample, particularly food, which is a problem in food hygiene. For this reason, in recent years, many food manufacturers have adopted metal inspection machines and X inspection apparatuses to remove metal, stone, and glass mixed in food during the food production process. However, since it is very difficult to detect hair, insects, and the like with the above-described inspection apparatus, at present, it is necessary to rely on a visual inspection by an operator, and there is a problem of increase in inspection cost and oversight.

  Therefore, in order to solve such problems, several foreign object inspection methods have been proposed. For example, a foreign matter inspection method has been proposed in which a light source such as an LED or a fluorescent lamp is applied to food flowing on a belt conveyor in the manufacturing process to detect foreign matter. In this case, if a fine foreign object such as hair moves, there is a problem in that an image flows at the time of photographing and the detection sensitivity is deteriorated, making detection difficult.

  In addition, food is irradiated with broadband light to form visible light, near-infrared light, and mid-near-infrared transmitted light images, each image is binarized, and a pattern is found in either image In such a case, a method for detecting a foreign object has been proposed (for example, see Patent Document 1). However, in such binarization processing, there is a problem that when the illumination condition fluctuates, the binarization processing does not function normally and it becomes difficult to detect.

  Also, the visible-near infrared absorption spectra of food and foreign substances are measured, the second derivative spectra of food and foreign substances are calculated, the wavelengths that are different between the two are identified, and the secondary using the specific wavelengths A method for generating a differential image and detecting foreign matter has been proposed (see, for example, Patent Document 2). However, in such a method, every time the food to be inspected changes, the absorption spectrum of the food and the foreign matter is measured and a wavelength having a difference is identified.

  In addition, when inspecting foods flowing at high speed on a belt conveyor in the manufacturing and inspection processes, the area of the region to be inspected becomes large, and it is actually difficult to shoot light other than visible light, It is expected that it will be difficult to implement the above method as a foreign matter inspection apparatus.

JP 2001-99783 A JP 2004-301690 A

  In the production and inspection process of food, for example, when detecting foreign matters mixed in food flowing on a belt conveyor, it is important how to inspect a large amount of food at high speed and without erroneous detection.

  For this purpose, it is necessary to increase the food conveyance speed, widen the inspection target area so as to inspect all of the food, and increase the image processing speed for detecting foreign matter from the captured image. However, when the conveyance speed of food is increased, an image flows. When the inspection target area is widened, the resolution of the photographing machine is deteriorated, and it is difficult to identify a thin substance such as hair.

  It is an object of the present invention to provide a foreign substance inspection apparatus capable of detecting a foreign substance mixed in food in a process of manufacturing and inspecting a sample, particularly food, at high speed and with high accuracy.

  In order to solve the above-mentioned problems, an embodiment of the present invention includes a conveying means for continuously transferring a sample, a strobe light source, and indirectly irradiating the front and back surfaces of the sample by reflecting light from the strobe light source. And a photographing means for photographing the sample in synchronization with light emission of the strobe light source, the photographing means divides the wavelength band of the reflected light from the sample into at least two, An image is generated by combining each image or difference image, and foreign matter is emphasized.

  According to the embodiment of the present invention, it is possible to provide a foreign substance inspection apparatus capable of detecting a foreign substance mixed in food at high speed and with high accuracy in the process of manufacturing and inspecting a sample, particularly food.

  In one embodiment of the present invention, strobe light such as an Xe lamp is used as a light source, and instantaneous measurement is performed in a short light emission time, thereby reducing blurring of foreign matters in an image.

  In addition, by using each image separated for each wavelength band and its difference image, false detection and missing detection are reduced. Furthermore, it is possible to perform high-speed detection by extracting a specific area from the image and setting only that area as an inspection target.

  In this embodiment, strobe light having a light emission amount that is one to two orders of magnitude greater than that of an LED or fluorescent lamp is used as light. The strobe light source is an Xe lamp having a relatively flat frequency distribution in the visible region.

  By using strobe light, measurement can be performed instantaneously in a short light emission time, so that even if the food moves at high speed, there is almost no blurring of the image. Further, glare due to a large amount of emitted light can be suppressed by using indirect illumination using a reflector, instead of directly irradiating food with strobe light.

  The detection of a foreign object makes it possible to identify the foreign object by extracting a region having a luminance change from the difference between the spectral characteristics of the foreign object and the food using each image separated for each wavelength band and the difference image thereof.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing a configuration of a system in which a foreign substance inspection apparatus is installed in a part of a food production process.

  In FIG. 1A, the foreign matter inspection apparatus 1 inspects the sample 4 to be inspected supplied from the food supply apparatus 20, and the sample 4 is sorted by the sorting means 19 according to the inspection result. As a result of the inspection, if it is determined that foreign matter is mixed in the sample 4, the sample 4 is stored in the tray 21 and is distinguished from a non-defective product that does not contain foreign matter.

  The foreign matter inspection apparatus 1 is provided with a transport unit 2 and irradiates light for inspection while the sample 4 placed so as not to overlap the transport unit 2 moves. The conveying means 2 is a belt conveyor configured by a belt having a constant width, for example, and is driven by a conveying driving device 3 such as a motor.

  A light source unit 5 for irradiating the sample 4 on the transport unit 2 with light is provided so as to cover the transport unit 2, and the sample 4 is irradiated with light.

  FIG. 1B is a cross-sectional view of the light source unit 5 as viewed from the direction in which the sample 4 indicated by the white arrow in FIG. 1A is conveyed.

  In the light source unit 5, strobe light sources 11a and 11b are arranged along the moving direction at both ends of the belt of the conveying means 2. The glare caused by the large amount of stroboscopic light emission is suppressed by indirect illumination using a reflector instead of directly irradiating the stroboscopic light on food.

  The light emitting portions of the strobe light sources 11 a and 11 b are installed so as to be hidden from the sample 4 by attaching a cover so that light is emitted almost upward, so that the light does not directly hit the sample 4. The reflecting plate 12 reflects the light emitted from the strobe light sources 11a and 11b so that the sample 4 is irradiated indirectly.

  The reflector 12 has a semi-cylindrical shape along the conveyance direction of the sample 4 so that light strikes the sample 4 as uniformly as possible.

  Note that when the reflected light 13 reflected by the sample 4 is photographed when the sample 4 comes below the lens 10 of the photographing means 6 such as a camera, the reflecting plate 12 has a hemispherical shape centered on the photographing position of the sample 4. If so, the sample 4 can be irradiated with more indirect illumination light.

  Returning to FIG. 1A, the photographing means 6 is provided above the reflecting plate 12 to photograph the sample 4 below the lens 10. The photographing means 6 is also positioned so that the light from the strobe light sources 11a and 11b does not enter directly.

  The photographing means 6 includes a lens 10, a filter 9, a prism 7 for splitting light, and one or more image sensors 8. The reflected light 13 from the sample 4 is split into three wavelength bands by the prism 7 via the lens 10 and is received by the image pickup device 8 such as a CCD or CMOS.

  The three wavelength bands are mainly red (R), green (G), and blue (B). Even if the wavelength band to be dispersed is not particularly concerned with RGB, foreign substance discrimination in the present invention can be performed as long as it can be divided into two or more wavelength bands. Further, if necessary, a filter 9 may be provided in front of the lens 10 to remove unnecessary wavelengths.

  The image received by the image sensor 8 is guided to an inter-image calculation unit 15 provided in the foreign object detection unit 16 and a specific luminance value change is extracted from each image. Thereafter, the foreign matter detection means 16 detects the foreign matter from the specific change in luminance value.

  The foreign object detection means 16 is a computer, performs arithmetic processing on the input image data according to a predetermined program, and displays the result on the connected display 17. Further, the control unit 18 is connected to the foreign matter detection unit 16 to control the sorting unit 19 that sorts the target sample 4 after the foreign matter is detected.

  Further, the control means 18 controls the photographing by the photographing means 6 according to the command data transmitted from the foreign matter detecting means 16, the control for synchronizing the light emission and photographing with the strobe light sources 11a and 11b, and the conveying speed of the conveying means 2. And control the shooting timing.

  FIG. 2 is a time chart showing the timing of flash emission and shooting. The timing control is executed by the control means 18 in accordance with the command data transmitted from the foreign object detection means 16 shown in FIG.

  In FIG. 2A, the sample 4 is moved at the speed V by the conveying means 2, and a certain range, that is, photographing areas 30a and 30b are photographed by the photographing means 6. The shooting width A is shot at the timing of shooting time T = A / V in order to eliminate omission of shooting.

  FIG. 2 (b) shows the exposure time t1 required for exposure. In the conventional case, the exposure time t1 of the photographing means 6 is used in order to obtain the required light quantity 31 by always lighting the LED and the fluorescent lamp. It was supported by making it longer.

  Since the light intensity of the LED or the fluorescent lamp is low, a light quantity 31 sufficient to identify a foreign object cannot be obtained unless the exposure time t1 is increased. However, if the exposure time t1 is lengthened, there is a possibility that an image in which foreign matter has flowed may occur, and adjustment is difficult.

  FIG. 3 is a diagram showing an example of an image when the hair is photographed while changing the exposure time. FIG. 3A shows that the conventional LED or fluorescent lamp is always turned on to increase the exposure time t1. FIG. 3B is an example using the strobe light of the present invention.

  As shown in FIG. 3A, an image flows through the linear foreign matter 35 such as hair, and the foreign matter image 36 has a shape stretched to a length determined by the product of the speed V and the exposure time t1. Further, there is a drawback that the luminance for the expanded area is lowered and the photographing sensitivity is extremely deteriorated.

  For example, if the width of the linear foreign material 35 is 50 μm, the moving speed V is 200 mm / s, and the exposure time t1 is 1 ms, the extended length V · t1 is 200 μm, which is four times the original width 50 μm. .

  And since a luminance value falls to 1/4 and a shape collapse | crumbles, it will become difficult to identify a foreign material. This effect is greater for thin foreign objects such as hair and small foreign objects, and the decrease in luminance value increases as the moving speed V increases. Therefore, the conventional method can hardly detect foreign objects.

  Further, if the aperture of the lens 10 is increased in order to obtain the amount of light, the amount of light increases, but the depth of focus becomes shallow. Therefore, it becomes difficult to focus the entire photographing area, and it is difficult to balance the amount of light and the depth of focus. Met.

  In the embodiment of the present invention, a strobe light source having a light emission luminance that is one to two digits larger than that of an LED or a fluorescent lamp is used as the light source.

  For example, the Xe strobe light source has a relatively flat characteristic in the visible light range where the wavelength band is 300 to 900 nm. In order to photograph the photographing areas 30a and 30b shown in FIG. 2A, photographing is performed at a timing of photographing time T = A / V as in the conventional case.

  On the other hand, as shown in FIG. 2C, the strobe is caused to emit light at a light emission time t2 and a cycle T = A / V, and a light quantity 32 is obtained. Since the strobe light source has a light emission luminance that is one to two orders of magnitude higher than that of an LED or a fluorescent lamp, the exposure time t1 shown in FIG. 2B can be taken as long as it is at least longer than the light emission time t2 of the strobe. The upper limit is the shooting width A of the shooting area.

  Since the strobe has a high luminance intensity, the light emission time can be reduced by one to two digits compared to conventional light sources such as LEDs and fluorescent lamps. For this reason, as shown in FIG. 3B, the linear foreign matter 35 such as the hair hardly has an image and becomes a foreign matter image 37 close to the shape of the original foreign matter.

  Accordingly, there is little decrease in luminance, and the foreign object detection sensitivity does not deteriorate. For example, if the width of the foreign matter is 50 μm, the moving speed V is 200 mm / s, and the light emission time t2 is 0.05 ms, the extended length V · t2 is 10 μm, which is at most 1.2 times that of the original foreign matter. The breadth is suppressed.

  In this way, since the luminance does not decrease and the shape does not change, it is possible to detect fine foreign matters such as hair and small foreign matters even if the moving speed is high. Further, since the luminance is high, the amount of reflected light is large, and the aperture of the lens 10 can be narrowed to increase the depth of focus, so that it is possible to prevent the entire photographing area from being out of focus. Furthermore, since shooting is performed with high brightness instantaneously, there is an advantage that it is not easily affected by disturbances such as vibration and light entering from the outside.

  Since the strobe light source has a large amount of light, shining or glare occurs on the surface of the sample directly when irradiated on the sample, and the correct spectral reflection of the original sample or foreign matter may not be obtained. Therefore, a method is provided in which the reflecting plate 12 is provided and the sample 4 is indirectly irradiated with the illumination light reflected by the reflecting plate 12.

  In addition, since the shadow of the sample 4 is recognized as a foreign object as a captured image, the reflector 12 is formed in a semi-cylindrical shape or a hemispherical shape so that the illumination light strikes the sample 4 as uniformly as possible from each direction in order to eliminate the shadow as much as possible. Is desirable.

  4 and 5 are cross-sectional views of the light source unit 5 as in FIG. 1B, and are examples showing structures for irradiating the sample 4 with a large amount of illumination light.

  If the sample 4 has a height, a shadow is likely to appear. Therefore, as shown in FIG. 4, auxiliary reflectors 12a and 12b are provided so as to shine light on the side surface of the sample 4 so as to eliminate the shadow. Furthermore, the light quantity from the side surface of the sample 4 can be adjusted by providing the auxiliary reflectors 12a and 12b with a slit and changing the reflection area by changing the slit width and the like. .

  In addition, as shown in FIG. 5, a light source 22 may be provided so that light transmitted through the belt of the conveying unit 2 to some extent is applied from below the belt. However, in this case, it is necessary to select the light amount of the light source 22 in consideration of the balance with the light amounts of the strobe light sources 11a and 11b. Moreover, since the belt of the conveying means 2 is transmitted, it is necessary to consider the belt structure.

  The sorting of the sample 4 after the detection of the foreign matter is performed by the control means 18 and the sorting means 19 shown in FIG. The position of foreign matter detection can be calculated by the foreign matter detection means 16 in the imaging area 30a shown in FIG. 2A, and the distance from the position to the sorting means 19 can be calculated.

  The time from the conveying speed V to the sorting means 19 is determined, and when the target sample 4 comes on the sorting means 19, the sorting mechanism is operated and stored in the tray 21. It is also possible to attach an encoder to the transport driving device 3 of the transport means 2 and calculate the distance from the pulse.

  FIG. 6 is a perspective view of part of the sorting means and the tray.

  When many samples 4 are arranged in the lateral direction of the conveying means 2 shown in FIG. 1B and only one of the samples 4 is attached with foreign matter, the sorting means 19 simply moves up and down. In this case, the non-defective samples 4 arranged side by side are also stored in the tray 21 and waste is generated.

  Therefore, as shown in FIG. 6, the air 42 is blown onto the sample 4 so that the sample to which foreign matter is attached is stored in the foreign matter tray 43 and the non-defective sample is stored in the tray 44.

  At the outlet of the conveying means 2, the sample 4 is dropped and stored in the tray 44. A plurality of air nozzles 40 are arranged in the belt width direction (Y-axis direction) of the conveying means 2 between the conveying means 2 and the tray 44, and each air nozzle 40 ejects air 42 by the electromagnetic valve 41. The amount can be controlled. The sample 4 and the linear foreign matter 35 that are blown off by the ejection of the air 42 are stored in the foreign matter tray 43.

  When the linear foreign matter 35 is detected in the transported sample 4, the position of the transport direction (X-axis direction) and the Y-axis direction are calculated by the control means 18, and at the outlet of the transport means 2, The air nozzle 40 corresponding to the X coordinate and the Y coordinate ejects air 42. The sample 4 and the linear foreign matter 35 to which the air 42 is applied are stored in the foreign matter tray 43. Since the portion where the air 42 is ejected is only the X-coordinate and Y-coordinate positions of the sample 4, the non-defective product 4 can be stored in the tray 44 instead of the foreign material tray 43 by distinguishing between the non-defective product 4 and the sample 4 to which foreign matter has adhered. it can.

  FIG. 7 is a perspective view of a part of the food supply device and the conveying means.

  Since the foreign substance inspection apparatus 1 shown in FIG. 1A mainly inspects linear foreign substances, it is difficult to detect non-linear foreign substances and liquids adhering to foods due to surface tension.

  Therefore, it is desirable to remove these foreign substances in advance. Although the sample 4 is mounted on the food supply device 20, when a linear foreign material 35, a small foreign material 38, and a liquid 39 such as moisture are also mounted together, the position before the sample 4 is supplied to the conveying means 2. Thus, a slit 51 through which the small foreign matter 38 and the liquid 39 can pass is provided in the width direction of the food supply device 20.

  Then, the food supply apparatus 20 is vibrated so that the small foreign matter 38 and the liquid 39 are removed from the slit 51. The removed small foreign matter 38 and liquid 39 are collected in the foreign matter receptacle 52.

  FIG. 8 is a graph showing the relationship between the wavelength of reflected light from a foreign object and the reflectance.

  The imaging means 6 shown in FIG. 1A includes a lens 10, a prism 7 for splitting received light, and one or more imaging elements 8, and reflected light 13 from the sample 4 is a lens. 10, the light is split into three wavelength bands of red (R), green (G), and blue (B) by the prism 7, and each wavelength band is received by an image sensor 8 such as a CCD or CMOS.

  A camera in which the prism 7 and the image sensor 8 are integrated is also commercially available, and may be used.

  In FIG. 8, the characteristic of the food 62 generally has a reflectance valley depending on the wavelength, but a foreign substance such as hair shows a relatively flat reflectance. Further, it is assumed that the foreign matter A60 has a high reflectance and the foreign matter B61 has a low reflectance. In the figure, B represents blue, G represents green, and R represents red.

  FIG. 9 is a screen diagram illustrating an example of a foreign object image captured by the image sensor 8. FIG. 9A is a B screen, FIG. 9B is a G screen, and FIG. 9C is a G screen and a B screen. It is GB screen which took the difference of.

  The R image, G image, and B image captured by the image sensor 8 are transmitted to the inter-image calculating means 15 to generate respective images. Moreover, since the image is composed of minute pixels, the difference between the images can also be calculated.

  In the screen B shown in FIG. 9A, the entire image is the surface of the food 62a, and the foreign matter 60a and the foreign matter 61a are attached thereon. The foreign object 60a is brighter than the food 62a, and the foreign object 61a is photographed with darker brightness.

  In the G screen shown in FIG. 9B, the food 62b is darker than the food 62a shown in FIG. 9A, and the foreign object 60b is brighter and the foreign object 61b is taken with darker brightness than the food 62b. .

  As shown in FIG. 8, the reflectances of the foreign matter A60 and the food 62 are close to each other in the blue (B) wavelength band, and it may be difficult to identify them on the B screen. FIG. 9 (c) is a screen obtained by taking the difference between the B screen shown in FIG. 9 (a) and the G screen shown in FIG. 9 (b). Can be prevented.

  In FIG. 8, in the B wavelength band and the G wavelength band, the reflectance of the foreign matter A60 and the foreign matter B61 does not change much, but the reflectance of the food 62 greatly changes.

  Therefore, taking the difference between the B screen and the G screen, the foreign matter A60 and the foreign matter B61 have a small difference in reflectance, whereas the difference in the reflectance of the food 62 is large, as shown in FIG. On the GB screen, the foreign matter 60c and the foreign matter 61c having a small difference and the food 62c having a large difference are emphasized, so that the foreign matter 60c and the foreign matter 61c can be easily identified.

  Since the difference between the screens is either bright or dark according to the reflectance characteristics, it is a very convenient technique for the binarization process performed in the image processing.

  In the above example, the description has been given focusing on the B wavelength band and the G wavelength band, but the same applies to the R wavelength band. In the example of FIG. 8, since the B wavelength band and the R wavelength band show similar characteristics, even if the difference between the G screen and the R screen is taken, the same result as in the case of the difference between the G screen and the B screen can be obtained. .

  FIG. 10 is a graph showing the relationship between the wavelength of reflected light from a foreign object and the reflectance as in FIG. 8, but the reflectance characteristics of the food 62 are different, and the characteristics are flat even when the wavelength is changed. This is an example.

  FIG. 11 is a screen diagram illustrating an example of a foreign object image captured by the image sensor 8. FIG. 11A is a B screen, FIG. 11B is a G screen, and FIG. 11C is a G screen. It is a GB screen obtained by taking the difference between the B screens.

  In the screen B shown in FIG. 11A, the difference in reflectance between the food 62d and the foreign matter 61d is large, so that the foreign matter 61d can be identified. The difference in reflectance between the food 62d and the foreign matter 60d is also large, but since both have high reflectance, the contrast is not clear, but the foreign matter 60d can be identified once.

  Similarly, in the G screen shown in FIG. 11B, since the difference in reflectance between the food 62e and the foreign matter 61e is large, the foreign matter 61e can be identified, and the difference in reflectance between the food 62e and the foreign matter 60e is also large. Can be identified.

  On the other hand, in the GB screen shown in FIG. 11 (c), as can be seen from FIG. 10, the difference in reflectance between the B wavelength band and the G wavelength band is small for each of the food 62f, the foreign object 60f, and the foreign object 61f. Each difference becomes the same level and cannot be identified.

  Since food has various components and colors, it is suitable for identifying food and foreign substances from the screens of the R, G, and B wavelength bands and the screens that have taken the differences between them. Is selected first, and then the inspection is performed by paying attention to the screen.

  In this way, the trouble of viewing many screens at a time can be saved, and errors such as oversight can be prevented.

  FIG. 12 is a graph showing the relationship between the wavelength of reflected light from a foreign object and the reflectance, as in FIG. 8, and FIG. 13 is a screen diagram showing an example of an image of a foreign object photographed by the image sensor as in FIG. .

  If the food is not necessarily composed of one component or the surface, and there are a plurality of reflectance characteristics on the surface of one food, for example, as shown in FIG. Suppose that there are three types, B, C. In the B wavelength band, the reflectance of the food 62 is closer to the reflectance of the foreign matter A60 indicated by the white square mark than the reflectance of the foreign matter B61 indicated by the black square mark.

  Therefore, on the B screen, the foreign object B61 can be identified, but the foreign object A60 can be predicted to be difficult to identify.

  As shown in FIG. 13, in the difference screen of the GB screen, the characteristics A and B of the food 62 are higher in contrast than the foreign objects 60 g and 61 g, but the characteristics C of the food 62 are different from the foreign objects 60 g and the foreign objects. Since the luminance difference is equivalent to 61 g, it is difficult to add contrast.

  Therefore, when the screen B is viewed, the luminance values of the foreign matter 60h and the foreign matter 61h are clearly different from the characteristic value of the food item 62, so that the characteristic value of the food item 62 can be distinguished from the foreign matter 60h and the foreign matter 61h. Therefore, by creating a screen that combines the G-B screen and the B screen, the foreign matter 60 i and the foreign matter 61 i can be identified from the background of the food 62.

  Here, in order to capture a foreign object as a bright image, the low-intensity foreign object 61i can be inverted to reverse the darkness, and can be captured as a bright luminance if synthesized.

  In FIG. 13 of the above example, for easy understanding, it seems that the foreign object can be detected only by the B screen, but in reality, the reflectance of the food surface is rarely constant, and it is as simple as the example. Therefore, a monochrome screen such as a B screen, a G screen, and an R screen, a difference screen between the monochrome screens, and a composite screen of the difference screen and the monochrome screen are generated and a trial inspection is performed, and an appropriate screen is selected.

  If the reflectance characteristics of the foreign material are known in advance, selecting a screen that can clearly distinguish the difference from the sample and looking only at this screen will allow you to miss the foreign material rather than gazing at multiple screens. Etc. can be prevented.

  Here, the three wavelength bands of visible light such as the B screen, the G screen, and the R screen are given as examples. However, as long as foreign substances can be identified, ultraviolet light, near infrared light, and infrared light can be used. I do not care. Further, a plurality of characteristic wavelengths may be extracted from spectral characteristics divided for each single wavelength by narrowing down the wavelength region, and screen differences or synthesis may be performed.

  FIG. 14 is a cross-sectional view of the light source unit 5 similar to FIG.

  The main configuration of the imaging means 6 includes a dichroic mirror 71 that reflects short wavelength light and transmits long wavelength, a camera 70a that images short wavelength light, and a camera 70b that images long wavelength light, A lens 10 for focusing, and a dark room 72 that fixes them and prevents external light from entering, and sends the obtained image to the inter-image calculation means 15 to generate a difference image or a composite image. To detect foreign matter.

  Of the reflected light 13 from the sample 4, the short wavelength light 13a reflected by the dichroic mirror 71 is transmitted through the lens 10 and picked up by the camera 70a, and the long wavelength reflected light 13b transmitted through the dichroic mirror 71 is the camera 70b. The image is taken. The wavelength boundary may be arbitrarily determined so as to be a spectral division that can identify food as a sample and foreign substances.

  FIG. 15 is a graph showing the relationship between the wavelength and the wavelength sensitivity, and the reflected light from the sample 4 is divided into the short wavelength side characteristic a and the long wavelength side characteristic b at the wavelength indicated by the thick line. The foreign object is identified using the generated screen.

  FIG. 16 is a cross-sectional view of the light source unit 5, as in FIG. 16B, in which the example shown in FIG. 15 is further developed and two dichroic mirrors 71 are provided in the photographing means 6.

  Of the reflected light 13 from the sample 4, the short wavelength light 13a reflected by the dichroic mirror 71a is imaged by the camera 70a. Of the reflected light transmitted through the dichroic mirror 71a, the medium wavelength light 13b is reflected by the dichroic mirror 71b and imaged by the camera 70b. The long wavelength light 13c transmitted through the dichroic mirror 71b is imaged by the camera 70c.

  FIG. 17 is a graph showing the relationship between wavelength and wavelength sensitivity. The reflected light from the sample 4 is divided into a characteristic a on the short wavelength side, a characteristic b on the medium wavelength side, and a characteristic c on the long wavelength side at the wavelength indicated by the thick line. Foreign objects are identified using screens that are divided and generated from the respective characteristics.

  The wavelength boundary may be arbitrarily determined so as to be a spectral division that can identify food as a sample and foreign substances. The reflected light spectrum may be a half mirror or a prism instead of the dichroic mirror.

  If foreign matter adhering to the sample is likely to adhere to the same part of the sample, image processing is performed by acquiring a screen for identifying foreign matters by focusing on a specific region that is easy to attach instead of the entire sample. The processing time required for is shortened.

  Further, if the image signal is differentiated, the place where the change is large, that is, the edge of the foreign matter is emphasized, so that the foreign matter can be easily identified. In addition, for example, in order to detect a long and thin line-like foreign object such as hair, after a binarization process of light and dark from a target region, detection by a line segment that selects a certain length or more is possible. .

  However, in this case, a long linear foreign object may be cut off and become short and cannot be detected. In order to prevent this, if it is determined that there is continuity even if the line is broken, it can be detected as an elongated linear foreign object by connecting the lines in image processing.

The block diagram which shows the structure of the system which installed the foreign material inspection apparatus in a part of manufacturing process of foodstuffs. A time chart showing the timing of flash emission and shooting. The figure which shows the example of an image when changing the exposure time and image | photographing the hair. Sectional drawing of a light source unit. Sectional drawing of a light source unit. The perspective view of a part of sorting means and tray. The perspective view of a part of food supply apparatus and a conveyance means. The graph showing the relationship between the wavelength of the reflected light from a foreign material, and a reflectance. The screen figure which shows the example of the image of the foreign material image | photographed with the image pick-up element. The graph showing the relationship between the wavelength of the reflected light from a foreign material, and a reflectance. The screen figure which shows the example of the image of the foreign material image | photographed with the image pick-up element. The graph showing the relationship between the wavelength of the reflected light from a foreign material, and a reflectance. The screen figure which shows the example of the image of the foreign material image | photographed with the image pick-up element. Sectional drawing of a light source unit. The graph which shows the relationship between a wavelength and wavelength sensitivity. Sectional drawing of a light source unit. The graph which shows the relationship between a wavelength and wavelength sensitivity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Foreign substance inspection apparatus, 2 ... Conveyance means, 3 ... Conveyance drive apparatus, 4 ... Sample, 5 ... Light source unit, 6 ... Imaging means, 7 ... Prism, 8 ... Imaging element, 9 ... Filter, 10 ... Lens, 11a ... Strobe light source, 11b ... Strobe light source, 12 ... reflector, 13 ... reflected light, 15 ... image calculation means, 16 ... foreign matter detection means, 17 ... display, 18 ... control means, 19 ... sorting means, 20 ... food supply Apparatus, 21 ... Tray, 22 ... Light source, 30a ... Shooting area, 30b ... Shooting area, 31 ... Light quantity, 32 ... Light quantity, 35 ... Linear foreign matter, 36 ... Foreign object image, 37 ... Foreign object image, 38 ... Small foreign matter, 39 ... Liquid, 40 ... Air nozzle, 41 ... Solenoid valve, 42 ... Air, 43 ... Foreign matter tray, 44 ... Tray, 51 ... Slit, 52 ... Foreign matter receptacle, 60 ... Foreign matter A, 61 ... Foreign matter B, 62 ... Food, 70a …camera, 0b ... camera, 70c ... camera, 71 ... die clock mirror, 72 ... dark room.

Claims (9)

  Conveying means for continuously transferring the sample, a strobe light source, a reflector that reflects light from the strobe light source and indirectly irradiates the front and back surfaces of the sample, and a wavelength band of reflected light from the sample A photographing means for photographing the sample in synchronism with light emission of the strobe light source, and difference images generated from a plurality of images photographed by the photographing means, or among the plurality of images A foreign matter inspection apparatus comprising: a calculation unit that generates a composite image of at least one image and the difference image and displays the composite image on a display. The foreign matter inspection apparatus according to claim 1,
An apparatus for inspecting foreign matter, wherein an image having a contrast capable of discriminating between the sample and the foreign matter is selected from the plurality of images, the difference image, and the composite image, and used for the inspection of the sample. The foreign matter inspection apparatus according to claim 1,
A foreign matter inspection apparatus, wherein an auxiliary reflecting plate is further provided between the reflecting plate and the sample. The foreign matter inspection apparatus according to claim 1,
A foreign matter inspection apparatus comprising a light source for irradiating the sample through the transport unit. The foreign matter inspection apparatus according to claim 1,
At least one of the plurality of images, the difference image, and the composite image is selected and used for the inspection of the sample. The foreign matter inspection apparatus according to claim 1,
The foreign substance inspection apparatus, wherein the plurality of images are images of a red wavelength band, a green wavelength band, and a blue wavelength band. The foreign matter inspection apparatus according to claim 1,
A foreign matter inspection apparatus, wherein the reflected light from the sample is dispersed with a dichroic mirror. The foreign matter inspection apparatus according to claim 1,
The foreign object inspection apparatus, wherein the reflection plate has a semi-cylindrical shape. The foreign matter inspection apparatus according to claim 1,
The foreign object inspection apparatus, wherein the reflector is hemispherical.

Images