JP2010112943A - Device and method for discriminating foreign matter contamination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy in discriminating foreign matter included in an inspection object wetted by water. <P>SOLUTION: A device (6) for discriminating foreign matter contamination includes: an irradiation light source system (7) for irradiating linearly-polarized laser light having a specific single wavelength to the inspection object (S); a light receiving optical system (8) having light receiving elements (PD1-PDn) for receiving reflected/scattered light including at least a polarization component in a direction different from a polarization direction of the laser light, among each reflected/scattered light including reflected/scattered light including a direction component different from the polarization direction of the laser light by the inspection object (S) itself and reflected light in the same polarization direction as the laser light by water on the surface of the inspection object (S); and a foreign matter contamination discrimination means (11A) for discriminating whether the inspection object (S) is a foreign matter or not, based on the polarization component in the direction different from the polarization direction of the laser light of the received reflected/scattered light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a foreign matter contamination determination device and a foreign matter contamination determination method for determining and detecting foreign matter contamination in an object to be inspected, such as food, and more particularly, an optical foreign matter contamination determination device that uses laser light for foreign matter detection, and The present invention relates to a foreign matter contamination determination method.

In the food industry, it is a big social problem that foreign matters are mixed in foods and the like, and there are many cases where the management base is shaken. Therefore, conventionally, foreign substances mixed in food are detected and removed by various methods. For example, in raisins as food, typical examples of foreign substances that may be mixed in the production and distribution process include pebbles, tree branches and stems (stems and fragments), vinyl, plastic pieces, etc. It is done. In addition, for example, shells and astringent skin are typical examples of foreign matters for walnuts as food.
Conventionally, as a method for detecting foreign matters mixed in foods, etc., a method for determining by metal detection method using electromagnetic induction, inspection by X-ray transmission, or image processing such as the shape of the object itself or the appearance color ( For example, Japanese Patent Application Laid-Open No. 2000-162136 is known. However, in these methods, it has been difficult to discriminate foreign objects that have similar appearances and colors, non-metallic materials, and materials that have substantially the same X-ray transmittance.

In addition, the following prior arts (J01) to (J04) are conventionally known as foreign object detection methods using light.
(J01) Technology described in Patent Document 2 (Japanese Patent Laid-Open No. 61-196143) Patent Document 2 scans a monochromatic light beam in a width direction perpendicular to the moving direction of a sheet-like object (11). Then, when the transmitted light beam is detected by the light receiver (22), the transmitted light introduced from the slit (52) of the light receiver (22) is diffused by the diffusion plate (54), and the light guide rod (55). ) And the sensitivity of light incident from each position in the width direction is made uniform by detecting it with the photomultiplier element (68).
That is, Patent Document 2 describes a technique for improving the accuracy of discriminating defects and foreign matters by reducing sensitivity variations in the width direction.

(J02) Technology described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2007-64734) Patent Document 3 irradiates a falling powder particle body in a horizontal direction while irradiating the powder material (F). Describes a technique in which a light diffusing member (37) is disposed on the opposite side of the laser light projecting mechanism (31) and diffusely reflected when the reflected light is received and foreign matter is discriminated. In the technique described in Patent Document 2, even when a falling granular material (F) causes unevenness in the layer thickness or density, a gap may be formed between the granular materials (F). The laser light that has passed through is diffusely reflected by the light diffusing member (37), so that the amount of light received by the light detection unit (40) is made to be uniform regardless of the layer thickness and density, and there is no foreign matter. The difference (contrast) between when and when there is a foreign object is clarified, and foreign object detection is performed with high accuracy.

(J03) Technology described in Patent Document 4 (Japanese Patent Application Laid-Open No. 2005-233724) Patent Document 4 describes a technique based on a difference in light-receiving intensity of transmitted light of near-infrared light having a single wavelength (wavelength 980 nm) irradiated on food. Thus, a technique for detecting the entry of foreign matter is described. Patent Document 2 discriminates between the presence of foreign matter and the type of foreign matter mixed in based on the received light intensity of transmitted light when two infrared wavelengths (wavelengths of 900 nm and 1300 nm) are irradiated. The technology is also described.
(J04) Technology described in Patent Document 5 (Japanese Patent Application Laid-Open No. 2007-278846) Patent Document 5 includes reflected light of a visible laser beam having a wavelength of 532 nm and an infrared laser having a wavelength of 980 nm irradiated on food. A technique for detecting the contamination of foreign matters based on the intensity ratio of reflected light to reflected light is described.

JP 2000-162136 A JP-A-61-196143 (page 4, upper right column, lines 4 to 20, lines 2, 7, and 9) JP 2007-64734 A (“0015”, “0022”, “0044” to “0049”, FIGS. 5 and 6) Japanese Patent Laying-Open No. 2005-233724 (FIGS. 2 and 4) JP 2007-278846 A (“0018”, FIGS. 1 and 2)

(Problems of conventional technology)
In the foreign matter contamination determination apparatus using laser light as in the prior arts (J01) to (J04), accuracy (foreign matter detected from all foreign matters) between a dry subject to be inspected and a subject to be wetted with water. A large difference was observed in the detection rate, which is the ratio of the product, and the yield, which is the ratio of the product conveyed to the non-defective product with respect to the total amount.
When inspecting a test object wet with water, laser light may be reflected by the surface water of a good product wet with water compared to a dry test object, and the non-defective product may be misidentified or misidentified. There was a problem that the accuracy decreased.

  In particular, when inspecting raisins as an object to be inspected, it may be difficult to transport in the packing or transporting process due to stickiness due to sugar in the packing or processing process of raisins, so it may be loosened by adding water. . Further, in order to remove dust, sand, stones, etc. adhering to the object to be inspected, it may be washed with water. Even in the foreign matter contamination determination stage, if the raisins are hardened in a dumpling shape, a good product in the dumpling shape may be determined as a foreign matter and may be loosened with water. In addition to raisins, if the object to be inspected is stored in a refrigerator or freezer, the surface may become wet due to condensation or the like if it is taken out of the storage location for foreign matter contamination determination. . In addition, depending on the elapsed time after wetting the object to be inspected with water, a part of the object to be inspected once wet may be dried. In some cases, it may be in a mixed state, and the accuracy of discriminating foreign matter is reduced.

  This invention makes it a technical subject to improve the precision which discriminate | determines the foreign material contained in the to-be-inspected object wet with water.

In order to solve the technical problem, the foreign matter contamination determination apparatus according to claim 1 comprises:
An irradiation light source system for irradiating a test object with a laser beam having a specific single wavelength and linearly polarized light;
Reflected / scattered light including reflected / scattered light including a direction component different from the polarization direction of the laser light by the inspection object itself and reflected light having the same polarization direction as the laser light due to water on the surface of the inspection object A light receiving optical system having a light receiving element that receives reflected / scattered light including at least a polarization component in a direction different from the polarization direction of the laser light in the light;
Foreign matter mixing determination means for determining whether the object to be inspected is a foreign matter based on a polarization component in a direction different from the polarization direction of the laser light of the received reflected / scattered light,
It is provided with.

The invention according to claim 2 is the foreign matter contamination determination apparatus according to claim 1,
A polarizing optical element that is disposed on the optical path of the reflected / scattered light and that transmits light having a polarization component in a direction orthogonal to the polarization direction of the laser light included in the reflected / scattered light, and has passed through the polarizing optical element The light receiving optical system having the light receiving element for receiving light,
It is provided with.

According to a third aspect of the present invention, in the foreign matter contamination determination apparatus according to the first aspect,
A polarizing optical element disposed on an optical path of the reflected / scattered light and separating the reflected / scattered light into components of a first polarization direction and a second polarization direction orthogonal to each other; and light in the first polarization direction A light receiving optical system comprising: a first light receiving element that receives light and a second light receiving element that receives light in the second polarization direction; and
A direction orthogonal to the polarization direction of the laser light based on the light in the first polarization direction, the light in the second polarization direction, and the polarization direction of the laser light irradiated on the object to be inspected. Orthogonal component computing means for computing the polarization component of
The foreign substance contamination determination means for determining whether the object to be inspected is a foreign substance based on a polarization component in a direction orthogonal to the polarization direction of the laser light calculated by the orthogonal component calculation means;
It is provided with.

In order to solve the technical problem, the foreign matter contamination determination method of the invention according to claim 4 is:
Irradiate a test object with a specific single wavelength and linearly polarized laser beam,
Reflected / scattered light including reflected / scattered light including a direction component different from the polarization direction of the laser light by the inspection object itself and reflected light having the same polarization direction as the laser light due to water on the surface of the inspection object Receiving reflected / scattered light containing at least a polarization component in a direction different from the polarization direction of the laser light in the light,
Based on the polarization component of the received reflected / scattered light in a direction different from the polarization direction of the laser beam, it is determined whether or not the object to be inspected is a foreign substance.

According to the first and fourth aspects of the present invention, discrimination is performed based on reflected / scattered light including a direction component different from the polarization direction of the laser light from the object to be inspected, and linearly polarized incident laser light. The influence of reflected light caused by water having the same polarization direction can be suppressed, and the accuracy of discriminating foreign matter contained in the test object wet with water can be improved.
According to the second aspect of the present invention, foreign matter can be identified based on the component of the polarization direction orthogonal to the linearly polarized incident laser light that has passed through the polarizing optical element, and the adverse effect of reflection in water can be suppressed. .
According to the third aspect of the present invention, foreign matter can be determined based on the polarization component in a direction orthogonal to the polarization direction of the laser light that does not include reflected light in water, and the accuracy of determining the foreign matter is improved. Can be improved.

FIG. 1 is an explanatory diagram of a food sample sorting apparatus having a foreign matter contamination determination apparatus according to Embodiment 1 of the present invention. FIG. 2 is an enlarged explanatory view of a main part of the foreign matter contamination determination apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of history data according to the first embodiment. FIG. 4 is a flowchart of the foreign matter mixing determination process according to the first embodiment. FIG. 5 is a flowchart of the foreign object pixel discrimination process according to the first embodiment. FIG. 6 is a flowchart of the size filter process according to the first embodiment. FIG. 7 is an explanatory diagram of an example of a signal in the light receiving element of the object to be inspected in Example 1, FIG. 7A is an explanatory diagram of a conventional case in which a polarizing filter is not used, and FIG. 7B is an implementation in which a polarizing filter is used. FIG. 6 is an explanatory diagram in the case of Example 1. FIG. 8 is an enlarged explanatory view of a main part of the foreign matter contamination determination apparatus according to the second embodiment of the present invention and corresponds to FIG. 2 according to the first embodiment. FIG. 9 is an explanatory diagram of a calculation method for removing the influence of water from the reflected / scattered light according to the second embodiment. FIG. 10 is an explanatory diagram of the measurement results of the spectral characteristics of raisins and stems, and is a graph in which the horizontal axis represents wavelength and the vertical axis represents reflectance. FIG. 11 is an explanatory diagram of the apparatus used in Comparative Example 1 and Experimental Example 1. 12 is an explanatory diagram of the experimental results of Comparative Example 1 and Experimental Example 1. FIG. 12A is a graph of the experimental results of Comparative Example 1, and FIG. 12B is a graph of the experimental results of Experimental Example 1. 13 is an explanatory diagram of the experimental results of Comparative Example 2 and Experimental Example 2, FIG. 13A is a graph of the experimental results of Comparative Example 2, and FIG. 13B is a graph of the experimental results of Experimental Example 2. 14 is an explanatory diagram of the experimental results of Comparative Example 3 and Experimental Example 3, FIG. 14A is a graph of the experimental results of Comparative Example 3, and FIG. 14B is a graph of the experimental results of Experimental Example 3. 15 is an explanatory diagram of the experimental results of Comparative Example 4 and Experimental Example 4, FIG. 15A is a graph of the experimental results of Comparative Example 4, and FIG. 15B is a graph of the experimental results of Experimental Example 4. 16 is an explanatory diagram of the experimental results of Comparative Example 5 and Experimental Example 5, FIG. 16A is a graph of the experimental results of Comparative Example 5, and FIG. 16B is a graph of the experimental results of Experimental Example 5. 17 is an explanatory diagram of the experimental results of Comparative Example 6 and Experimental Example 6, FIG. 17A is a graph of the experimental results of Comparative Example 6, and FIG. 17B is a graph of the experimental results of Experimental Example 6. 18 is an explanatory diagram of the experimental results of Comparative Example 7 and Experimental Example 7, FIG. 18A is a graph of the experimental results of Comparative Example 7, and FIG. 18B is a graph of the experimental results of Experimental Example 7. 19 is an explanatory diagram of the experimental results of Comparative Example 8 and Experimental Example 8, FIG. 19A is a graph of the experimental results of Comparative Example 8, and FIG. 19B is a graph of the experimental results of Experimental Example 8. FIG. 20 is an explanatory diagram of an experimental apparatus used in Experimental Example 9. FIG. 21 is an explanatory diagram of the experimental results of Experimental Example 9. FIG. 21A is a graph of the intensity of the detected reflected / scattered light, and FIG. 21B is the intensity of the reflected / scattered light of FIG. It is a graph normalized as 1. 22 is an explanatory diagram of the experimental results of Experimental Example 10, FIG. 22A is a graph of the intensity of the detected reflected / scattered light, and FIG. 22B is the intensity of the reflected / scattered light data of FIG. It is a graph normalized as 1. FIG. 23 is an explanatory diagram of experimental results of Experimental Example 11 and Comparative Example 11, FIG. 23A is an explanatory diagram of experimental results of Comparative Example 11, and FIG. 23B is an explanatory diagram of experimental results of Experimental Example 11. FIG. 24 is an experimental apparatus diagram of an angle distribution of scattered light from a sample at the time of laser light irradiation in Experimental Example 12. FIG. 25 is an explanatory diagram of the experimental results of Comparative Example 12, and is a graph of the experimental results of irradiating raisins and stems wet with water to a 830 nm laser beam without installing a polarizing filter. FIG. 26 is an explanatory diagram of an experimental result of Experimental Example 12, and is a graph of an experimental result in which a raisin and a stem wet with water with a polarizing filter installed are irradiated with 830 nm laser light. It is a graph of the experimental result of the raisins and stem of 90 degrees of polarization directions. FIG. 27 is an explanatory diagram of the measurement results of the spectral characteristics of walnuts, shells and astringent skin corresponding to FIG. 10 of Experimental Examples 1 to 8, where the horizontal axis represents wavelength and the vertical axis represents reflectance. is there. FIG. 28 is an explanatory diagram of an experimental apparatus for an experiment on the scattered light angle distribution from the sample at the time of laser light irradiation in Experimental Example 13. FIG. 29 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnuts, shells and partition walls with a laser beam of 532 nm. FIG. 30 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnut nuts, shells, and partition walls with 635 nm laser light. FIG. 31 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnut nuts, shells and partition walls with 830 nm laser light.

Next, examples as specific examples of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.

FIG. 1 is an explanatory diagram of a food sample sorting apparatus having a foreign matter contamination determination apparatus according to Embodiment 1 of the present invention.
FIG. 2 is an enlarged explanatory view of a main part of the foreign matter contamination determination apparatus according to the first embodiment of the present invention.
In FIG. 1, a food sample sorting apparatus 1 as an example of a foreign matter sorting apparatus according to the first embodiment includes a loading unit 1a into which a food sample S as an example of a test object is loaded, and a sample loaded from the loading unit 1a. And a sample transporting member 2 to be transported. The sample transport member 2 is supported by a vibration device 3 that vibrates the sample transport member 2 and transports the sample on the sample transport member 2.
1 and 2, the food sample S transported to the right end (+ Y end) by the sample transport member 2 falls from the sample transport member 2 and is transported while falling down the fall transport path 4 vertically downward. The In the middle of the falling conveyance path 4, a foreign matter contamination determination area 5 is set, and a foreign matter contamination determination device 6 is disposed on the side of the foreign matter contamination determination area 5.

  In FIG. 2, the foreign matter contamination determination device (foreign matter detection device) 6 includes a laser light source device (irradiation light source system) 7 that irradiates the foreign matter contamination determination region 5 with laser light. The laser light source device 7 of Example 1 has a plurality of lasers LS1 to LSn. Each of the lasers LS1 to LSn emits laser beams having different wavelengths at a predetermined specific single wavelength. The lasers LS1 to LSn are lasers LS1 to radiate laser light having a wavelength capable of detecting a foreign substance according to the type and state of an object to be inspected, a required detection rate, a yield, and the like. LSn is selectively used. That is, as the lasers LS1 to LSn, for example, a laser light source that outputs laser light with a specific wavelength in the visible region such as blue, green, and red, or a laser light source that outputs laser light with a specific wavelength in the infrared region Can be used. In the first embodiment, two specific lasers are selected from a plurality of lasers LS1 to LSn according to the type of the object to be inspected and set by the user, and have different single wavelengths. Two laser beams are set to be irradiated.

The laser light emitted from the lasers LS1 to LSn passes through the first polarizing optical element 7a that passes only the component in the specific polarization direction, and is the laser light only in the specific polarization direction, so-called linearly polarized laser light. It becomes. As the first polarizing optical element 7a, a polarizing optical element that can pass only a component in a specific polarization direction can be used, and a polarizing filter or a polarizing beam splitter can be used.
The linearly polarized laser light is reflected by a rotating polygon mirror (polygon mirror) PM that has a plurality of reflecting mirrors and is driven to rotate at a high speed, and scans (scans) the foreign matter contamination determination area 5.
A laser light source device (irradiation light source system) 7 of Example 1 is configured by the lasers LS1 to LSn, the first polarizing optical element 7a, the polygon mirror PM, and the like.

  Below the laser light source device 7 is a light receiving device (light receiving device) that receives the reflected / scattered light of the food sample S passing through the foreign matter contamination determination region 5 and the laser light reflected / scattered by the foreign matter and converts it into an electrical signal. An optical system) 8 is arranged. The light receiver 8 includes a second polarizing optical element 8a through which the reflected / scattered light reflected and scattered by the inspection object S passes through the laser light applied to the inspection object S in the foreign matter mixing determination area 5. The second polarizing optical element 8a of the first embodiment is configured by a polarizing filter that is a polarizing optical element that can pass only a component in a specific polarization direction. In addition, the second polarizing optical element 8a of Example 1 passes only light in an orthogonal direction that is an example of a polarization direction different from the polarization direction of the linearly polarized laser light that has passed through the first polarizing optical element 7a. It is arranged to let you.

The laser light that has passed through the polarizing optical element 8a is received by the light receiving elements PD1 to PDn provided corresponding to the lasers LS1 to LSn. The light receiving elements PD1 to PDn of Example 1 are configured by light receiving elements configured by photomultiplier tubes. In addition, a light receiving element is not limited to a photomultiplier tube, For example, conventionally well-known light receiving elements, such as a photodiode, are employable.
The light receiving portions of the light receiving elements PD1 to PDn support wavelength selection filters FL1 to FLn that pass only light in the vicinity of the wavelength range of the laser light output from the lasers LS1 to LSn.
The light receiver 8 of the first embodiment is configured by the light receiving elements PD1 to PDn, the second polarizing optical element 8a, the wavelength selection filters FL1 to FLn, and the like.

A light intensity measuring device 10 is connected to the light receiving elements PD1 to PDn of the light receiving device 8, and the light intensity measuring device 10 measures (detects) light intensity based on an electric signal input from the light receiving device 8. ) An arithmetic processing device 11 is connected to the light intensity measuring device 10, and an output signal from the light intensity measuring device 10 is input to the foreign matter contamination determination means 11 A of the arithmetic processing device 11.
Based on the intensity of light input from the light intensity measuring device 10, the foreign matter contamination determination means 11A determines whether the object that has passed through the foreign matter contamination determination area 5 is a food sample, a so-called good product, a stem, a tree branch, a stone It is discriminated whether it is a foreign matter such as. The foreign matter contamination determination unit 11A according to the first embodiment includes a filter processing unit 11A1, a foreign matter contamination determination value storage unit 11A2, a foreign matter pixel determination unit 11A3, a discrimination history data storage unit 11A4, a discrimination result update unit 11A5, and a size filter. And processing means 11A6.

The filter processing unit 11A1 executes conventionally known filter processing such as smoothing, enhancement, differentiation, and edge enhancement based on the received signal (see, for example, Japanese Patent Laid-Open No. 2001-99783).
The foreign matter contamination determination value storage unit 11A2 stores a foreign matter contamination determination value for determining whether or not the sample S is a foreign matter or defective quality. In the first embodiment, foreign matter contamination determination values measured in advance through experiments or the like are stored and inspected for the reflected / scattered light of each laser beam irradiated according to the type of the object to be inspected. The foreign substance contamination determination value corresponding to the object to be inspected can be read out. In Example 1, the upper limit L1 and the lower limit L2 for determining that the intensity R1 of the first laser beam is non-defective and the intensity R2 of the second laser beam are non-defective for each object to be inspected. An upper limit value L3 and a lower limit value L4 that are determined to be present, and an upper limit value L5 and a lower limit value L6 that are determined that the intensity ratio R2 / R1 of the two laser beams is non-defective are stored.
The foreign object pixel determination unit 11A3 is based on the foreign object mixing determination value for determining whether or not it is a foreign object stored in the foreign object mixing determination value storage unit 11A2 of the arithmetic processing unit 11, and the light intensity after the filter processing. Thus, it is determined whether the minute area where the light is reflected / scattered on the object to be inspected on the foreign object contamination determination area 5 is a good area (non-defective pixel) or a foreign area (foreign pixel).

FIG. 3 is an explanatory diagram of history data according to the first embodiment.
The discrimination history data storage unit 11A4 stores history data of discrimination results discriminated by the foreign object pixel discrimination unit 11A3. As shown in FIG. 3, the discrimination history data storage unit 11A4 according to the first embodiment includes a main scanning direction (horizontal direction in the first embodiment) in which light scans the foreign matter contamination determination area 5 and a main scanning direction. The sub-scanning direction (vertical direction in the first embodiment) in which the object to be inspected moves vertically, each area (pixel, pixel) partitioned in a mesh pattern, and the determination result of the foreign object pixel determination unit 11A3 are associated with each other. Remember. That is, in the first embodiment, the determined pixel position and the determination result are stored in association with each other. In the first embodiment, 15 lines of data scanned for one line in the main scanning direction are stored as history data.

  The discrimination result update unit 11A5 updates the history data stored in the discrimination history data storage unit 11A4 with the scanning of the light emitted from the lasers LS1 to LSn. The discrimination result update unit 11A5 of the first embodiment reflects the light on the next surface as the polygon mirror PM rotates, and when scanning in the main scanning direction is started, the data for the oldest one line is deleted. By sequentially storing the latest scan data, the history data is sequentially updated as time passes.

The size filter processing means (removal symmetric foreign matter discriminating means) 11A6 is configured such that the inspected object determined to be a foreign matter is larger than a predetermined size based on the history data stored in the discrimination history data storage means 11A4. It is determined whether or not the foreign object is to be removed. In other words, filtering is performed to determine whether or not the size of the object to be inspected is determined to be greater than or equal to a preset size. The size filter processing unit 11A6 according to the first embodiment includes a foreign matter region extraction unit 11A6a, a region discrimination value storage unit 11A6b, and a foreign matter signal output unit 11A6c.
The foreign substance area extracting unit 11A6a extracts a foreign substance area composed of two or more consecutive foreign substance pixels in the main scanning direction or the sub-scanning direction based on the history data.

  The region discriminating value storage means 11A6b is a foreign object in which the object to be inspected is regarded as a non-defective product (for example, a stem having a predetermined size or less is regarded as a “non-defective product” in the raisin packing process) or too small to be removed. For this reason, the region discriminating value for discriminating whether or not the object to be inspected is a foreign object to be removed is stored. In Example 1, “18” is stored as the region discrimination value, and when the total number of consecutive foreign matter pixels is 18 or more, it is judged that the foreign matter is to be removed. In other words, in the size filter processing unit 11A6 of the first embodiment, in the history data, an object to be inspected having 18 or more foreign object pixels is determined as a foreign object to be removed, and an object to be inspected having less than 18 pixels is a foreign object to be removed. It is determined that there is no.

The foreign matter signal output means 11A6c outputs a foreign matter mixing signal including positional information of the foreign matter to be removed in the main scanning direction and the sub-scanning direction to the removal device control circuit when there is an object to be inspected that is to be removed.
The removal device control circuit 12 drives the foreign material removal device 13 disposed below the laser light source device 7 in response to an input signal from the foreign material contamination determination unit 11a.

1 and 2, the foreign substance removing device 13 ejects compressed air and moves an object that falls on the falling conveyance path 4 from the falling conveyance path 4 to the foreign substance collection path 14 of the food sample sorting apparatus 1. The foreign matter is collected in the foreign matter collection container 15. The foreign matter removing apparatus 13 according to the first embodiment has a plurality of jet outlets parallel to the main scanning direction, and air is supplied to the jet outlet corresponding to the position of the foreign matter to be removed in the main scanning direction so as to be ejected. It is configured.
Therefore, when it is determined by the foreign substance contamination determination unit 11a that the object passing through the foreign substance contamination determination area 5 is a foreign substance or a poor quality food sample S, the foreign substance removal area 13a facing the foreign substance removal apparatus 13 is detected. The foreign matter removing device 13 is driven in accordance with the timing of the transport to the foreign matter, and the foreign matter is collected in the foreign matter collection container 15 through the foreign matter collection path 14.
Downstream of the foreign matter removing device 13, a non-defective food sample S that has not been removed by the foreign matter removing device 13 is transported to the next step (for example, a cleaning step or a packaging step). A device 16 is arranged.

(Description of Flowchart of Example 1)
(Explanation of flowchart of foreign matter mixing determination processing)
FIG. 4 is a flowchart of the foreign matter mixing determination process according to the first embodiment.
The processing of each ST (step) in the flowchart of FIG. 4 is performed according to a program stored in the foreign matter contamination determination apparatus 6. Further, this process is executed in a multitasking manner in parallel with other various processes of the food sample sorting apparatus 1.
The flowchart shown in FIG. 4 is started by turning on the power of the foreign matter contamination determination apparatus 6.

In ST1 of FIG. 4, it is determined whether or not the user inputs measurement start from an operation unit (not shown). If yes (Y), the process proceeds to ST2. If no (N), ST1 is repeated.
In ST2, the following processes (1) to (3) are executed, and the process proceeds to ST3.
(1) Two lasers preset from the lasers LS1 to LSn, that is, the first laser and the second laser are driven to irradiate the first laser beam and the second laser beam.
(2) Start rotation of the polygon mirror PM.
(3) Operate the light receiving elements PD1 to PDn.
In ST3, it is determined whether or not the light receiving elements PD1 to PDn have received signals. If yes (Y), the process proceeds to ST4. If no (N), ST3 is repeated.

In ST4, conventionally known filter processing such as smoothing, enhancement, differentiation, and edge enhancement of the received signal (for example, see Japanese Patent Application Laid-Open No. 2001-99783) is executed, and the process proceeds to ST5.
In ST5, a foreign object pixel discrimination process (refer to a subroutine of FIG. 5 described later) is executed, and the process proceeds to ST6.
In ST6, it is determined whether or not the user inputs measurement end from the operation unit. If no (N), the process proceeds to ST7, and if yes (Y), the process proceeds to ST9.
In ST7, it is determined whether or not a signal for one scan (one line) from the one end side to the other end side of the foreign substance mixed region 5 is received. If yes (Y), the process proceeds to ST8. If no (N), the process returns to ST3.

In ST8, size filter processing (see a subroutine in FIG. 6 described later) is executed, and the process returns to ST3.
In ST9, the following processes (1) to (3) are executed, and the process returns to ST1.
(1) The lasers LS1 to LSn being driven are stopped, and the laser light irradiation is ended.
(2) Stop the rotational driving of the polygon mirror PM.
(3) Stop the light receiving elements PD1 to PDn.

(Description of flowchart of foreign object pixel discrimination processing)
FIG. 5 is a flowchart of the foreign object pixel discrimination process according to the first embodiment.
In ST11 of FIG. 5, it is determined whether or not the intensity R1 of the first laser light is equal to or higher than the upper limit L1 for determining good quality of the first laser light. If no (N), the process proceeds to ST12, and if yes (Y), the process proceeds to ST18.
In ST12, it is determined whether or not the intensity R1 of the first laser beam is equal to or less than a lower limit L2 for determining good quality of the first laser beam. If no (N), the process proceeds to ST13, and if yes (Y), the process proceeds to ST18.

In ST13, it is determined whether or not the intensity R2 of the second laser beam is equal to or higher than the upper limit L3 for determining good quality of the second laser beam. If no (N), the process proceeds to ST14. If yes (Y), the process proceeds to ST18.
In ST14, it is determined whether or not the intensity R2 of the second laser beam is equal to or lower than a lower limit L4 for determining good quality of the second laser beam. If no (N), the process proceeds to ST15, and if yes (Y), the process proceeds to ST18.
In ST15, it is determined whether or not the intensity ratio R2 / R1 between the intensity R1 of the first laser beam and the intensity R2 of the second laser beam is equal to or greater than the upper limit L5 for determining good products of the intensity ratio. If no (N), the process proceeds to ST16, and if yes (Y), the process proceeds to ST18.

In ST16, it is determined whether or not the intensity ratio R2 / R1 is equal to or less than a lower limit L6 for determining a non-defective product of the intensity ratio. If no (N), the process proceeds to ST17, and if yes (Y), the process proceeds to ST18.
In ST17, the received signal is determined as a non-defective pixel, and is stored and updated as history data in the determination history data storage unit 11A4. Then, the foreign object pixel determination process is terminated.
In ST18, the received signal is determined as a foreign pixel, and stored and updated as history data in the determination history data storage unit 11A4. Then, the foreign object pixel determination process is terminated.

(Description of size filter processing flowchart)
FIG. 6 is a flowchart of the size filter process according to the first embodiment.
In ST21 of FIG. 6, all foreign substance regions in which foreign substance pixels are continuous are extracted from the history data stored in the discrimination history data storage unit 11A4. Then, the process proceeds to ST22.
In ST22, it is determined whether or not the size of each extracted foreign substance region is greater than or equal to the region determination value. If yes (Y), the process proceeds to ST23, and, if no (N), the process proceeds to ST24.
In ST23, a foreign object area that is equal to or greater than the area determination value is determined as a removal target foreign object, and includes a foreign object region coordinate (the main scanning direction and sub-scanning direction positions of the foreign object area on the history data) determined as the removal target foreign object. Output mixed signal. Then, the process proceeds to ST24.
In ST24, it is determined whether or not all extracted foreign substance regions have been determined. If no (N), the process returns to ST22, and if yes (Y), the size filter process is terminated.

(Operation of Example 1)
In the food sample sorting apparatus 1 according to the first embodiment having the above-described configuration, when discrimination of foreign matter is started, a straight line having two wavelengths is applied to the object to be inspected (food sample S or foreign matter) that passes through the foreign matter contamination judgment area 5. Polarized laser light is irradiated. The linearly polarized laser light applied to the inspection object S is reflected on the surface of the inspection object S or scattered from the surface of the inspection object to the inside. In addition, when the surface of the inspection object S is wet with water, the laser light may be reflected by the water on the surface.
At this time, as a result of the study by the present inventors, the reflected / scattered light from the inspected object (non-defective product or foreign matter) S includes reflected / scattered light that includes a direction component having a polarization direction different from that of the irradiated linearly polarized laser light. While the light becomes so-called non-polarized reflected / scattered light, when the laser light is reflected by water adhering to the surface of the inspection object S, the laser light having the same polarization direction as the linearly polarized incident laser light is reflected. It has been found.

  Therefore, in the food sample sorting apparatus 1 of Example 1, the light including the reflected / scattered light from the inspection object S itself and the reflected light from the water on the surface is irradiated when passing through the polarizing optical element 8a. A component having the same polarization direction as that of the linearly polarized laser beam is cut. As a result, the reflected light from water having the same polarization direction as the irradiated laser light is cut. As a result, the light receiving elements PD1 to PDn receive light of intensity that excludes components in the same polarization direction as the irradiated linearly polarized laser light from the reflected / scattered light from the inspected object S itself. Non-defective products and foreign substances are discriminated based on the intensity and intensity ratio of the light.

FIG. 7 is an explanatory diagram of an example of a signal in the light receiving element of the object to be inspected in Example 1, FIG. 7A is an explanatory diagram of a conventional case in which a polarizing filter is not used, and FIG. 7B is an implementation in which a polarizing filter is used. FIG. 6 is an explanatory diagram in the case of Example 1.
In FIG. 7, in the conventional configuration in which the polarizing filter as the polarizing optical element 8a is not used, as shown in FIG. Intensity exceeding the value L1 (L3) may be measured, and there is a possibility that a non-defective product may be misidentified as foreign matter. On the other hand, when the polarizing filter 8a is used as in the first embodiment, as shown in FIG. 7B, the reflected light from water is cut by the polarizing filter 8a and is not measured by the light receiving elements PD1 to PDn. Misclassification is reduced. Therefore, in the food sample sorting apparatus 1 of Example 1, it is possible to discriminate between non-defective products and foreign matters based on the reflected light and scattered light from the inspected object S without being affected by the reflected light from water. The accuracy of discrimination can be improved.

In the food sample sorting apparatus 1 according to the first embodiment, the size filter process is executed to determine the foreign matter having a size that can be removed, and from the jet outlet corresponding to the position of the determined foreign matter in the main scanning direction. Air is blown out and removed. Therefore, it is possible to set so as not to remove a foreign substance that is regarded as a non-defective product, and air is ejected from the corresponding ejection port only to the foreign object to be removed. Therefore, it is possible to reduce that the non-defective product is caught and removed at the time of foreign matter removal, and the foreign matter removal accuracy can be improved.
Furthermore, in the food sample sorting apparatus 1 of Example 1, not only the intensity of the received light but also the intensity ratio is used for discrimination, and foreign matter having the same reflected light intensity for a specific single wavelength as a non-defective product is detected. The accuracy can be improved as compared with the case of using only the intensity when it is present.

  In addition, since the food sample sorting apparatus 1 of Example 1 uses a plurality of laser beams, each laser beam has excellent monochromaticity, and high-luminance light can be obtained at a specific wavelength. it can. Therefore, a large reflected light amount difference can be clearly detected by selecting a laser beam having an optimum wavelength according to the reflection characteristics of the food sample S to be selected. Furthermore, due to the directivity of the laser light, a large luminance difference can be obtained even if the foreign matter or the altered part (defective part) is in a minute range. As a result, by using a laser as a light source, it is possible to detect minute foreign matters and altered sites with high sensitivity. In particular, a transparent body such as a glass piece or plastic can easily detect the intensity ratio of reflected light by utilizing surface reflection, and foreign matter can be detected.

FIG. 8 is an enlarged explanatory view of a main part of the foreign matter contamination determination apparatus according to the second embodiment of the present invention and corresponds to FIG. 2 according to the first embodiment.
In the description of the second embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In FIG. 8, in the light receiver 8 ′ of the foreign matter contamination determination device (foreign matter detection device) 6 of the second embodiment, a polarizing beam splitter is used as the polarizing optical element 8 a ′ instead of the polarizing filter of the first embodiment. . The polarization beam splitter 8a ′ is a spectroscopic optical element that separates reflected / scattered light from the foreign matter contamination determination region 5, and is a polarization component (P-polarized light, first polarization direction) parallel to the incident surface 21 of the polarization beam splitter 8a ′. ) And the light having the polarization component (S-polarized light, second polarization direction) perpendicular to the incident surface 21 is reflected. The P-polarized light transmitted through the polarizing beam splitter 8a ′ is received by the first light receiving elements PD1 ′ to PDn ′, and the S-polarized light reflected by the polarizing beam splitter 8a ′ is received by the second light receiving element PD1 ″. Is received by PDn ″.
Wavelength selection filters FL1 ′ to FLn ′ and FL1 ″ that allow only light in the vicinity of the wavelength range of the laser beams output from the lasers LS1 to LSn to pass through the light receiving portions of the light receiving elements PD1 ′ to PDn ′ and PD1 ″ to PDn ″. ~ FLn "is supported.
A light receiver 8 'of the second embodiment is configured by the light receiving elements PD1' to PDn 'and PD1 "to PDn", the polarization beam splitter 8a', the wavelength selection filters FL1 'to FLn' and FL1 "to FLn", and the like. Yes.

  The light received by the first light receiving elements PD1 ′ to PDn ′ and the second light receiving elements PD1 ″ to PDn ″ of the light receiver 8 ′ is input to the light intensity measuring device 10 to measure the light intensity, It is output to the arithmetic processing unit 11 ′. In addition to the units 11A1 to 11A6 of the first embodiment, the foreign matter mixing determination unit 11A ′ of the arithmetic processing unit 11 ′ of the second embodiment includes a determination intensity calculation unit 11A7. The discriminating intensity calculation means 11A7 includes linearly polarized light component inclination angle storage means 11A7a, polarization direction calculation means 11A7b, and orthogonal component calculation means 11A7c, and each of the light receiving elements PD1 ′ to PDn ′ and PD1 ″ to PDn ″. Based on the received P-polarized light component and S-polarized light component, the discriminating intensity Xs ′ used in each means 11A2 to 11A6 is calculated.

FIG. 9 is an explanatory diagram of a calculation method for removing the influence of water from the reflected / scattered light according to the second embodiment.
The linearly polarized light component inclination angle storage means 11A7a stores the inclination angle θ of the linearly polarized light component with respect to the axis of the P-polarized light used when calculating the discriminating intensity Xs ′. In FIG. 9, when the laser light is reflected by the water on the surface of the inspection object S, the reflected light is separated by the polarization beam splitter 8a ′, and the P-polarized component Lp and the S-polarized component Ls are measured. The angle of the reflected light vector LS = (Lp, Ls) with respect to the P polarization axis is stored as the tilt angle θ of the linearly polarized light component. In Example 2, the inclination angle θ is determined by the laser beam in a state where a reflecting mirror (mirror) that reflects the linearly polarized laser beam is disposed in the foreign matter mixing determination area 5 before the inspection of the inspection object S. , And the P polarization component Lp of the linearly polarized reflected light detected by the first light receiving elements PD1 ′ to PDn ′ and the S polarization component Ls detected by the second light receiving elements PD1 ″ to PDn ″. , Derived from the following equation (1) and stored in advance.
θ = tan ⁻¹ (Ls / Lp) (1)

When the polarization direction calculating means 11A7b determines the contamination of the inspected object S, the polarization is the angle of the vector of the reflected / scattered light from the inspected object S passing through the foreign object contamination determining area 5 with respect to the P polarization axis. The direction γ is calculated. In FIG. 9, the reflected / scattered light from the foreign substance contamination determination area 5 is separated into a P-polarized component and an S-polarized component by the polarization beam splitter 8a ', and the reflected / scattered light detected by the first light receiving elements PD1' to PDn '. The P-polarized component RFp of the scattered light and the S-polarized component RFs detected by the second light receiving elements PD1 ″ to PDn ″ are detected. Therefore, the reflected / scattered light vector RF from the inspected object S becomes scattered light from the inspected object S itself when there is no influence of water, and when there is a reflection of the water film, the inspected object is detected. This is a vector in which components of the reflected / scattered light from the body S and the reflected light from the water film are combined. Then, the polarization direction calculation unit 11A7b according to the second embodiment calculates and derives the polarization direction γ that is the vector inclination direction from the following equation (2) based on the detected RFp and RFs.
γ = tan ⁻¹ (RFs / RFp) (2)

The orthogonal component calculation means 11A7c is configured to output the laser light based on the light RFp in the P-polarization direction, the light RFs in the S-polarization direction, and the inclination angle θ that is the polarization direction of the laser light irradiated on the inspection object S. The polarization component Xs ′ in the direction orthogonal to the inclination angle θ of the polarization direction is calculated. The orthogonal component calculation means 11A7c according to the second embodiment is based on the light intensity RFp of the P-polarized component light and the light intensity RFs of the S-polarized component, the polarization direction γ derived from RFp and RFs, and the inclination angle θ. Then, the intensity Xs ′ of the polarization component in the orthogonal direction is calculated from the following equation (3).
Xs ′ = {(RFp) ² + (RFs) ² } ^1/2 sin (γ−θ) (3)
That is, in the second embodiment, as shown in FIG. 9, the component in the inclination angle θ direction that is affected by water reflection, that is, the component in the P′-axis direction is not used for foreign matter determination, and the effect of water reflection The component in the orthogonal direction with a small inclination angle θ, that is, the component Xs ′ in the S′-axis direction is used for foreign object discrimination.

The means 11A2 to 11A6 of the second embodiment are the same as the means 11A2 to 11A6 of the first embodiment in place of the intensities R1 and R2 in the S′-axis direction of the first laser light and the second laser light. Since the same processing is executed only by using the components Xs1 ′ and Xs2 ′, detailed description of each means 11A2 to 11A6 of the second embodiment will be omitted for simplification of description.
Further, in the second embodiment, only the process of calculating the polarization direction γ and calculating the intensity Xs ′ of the polarization component in the orthogonal direction is executed between ST4 and ST5 of FIG. 4 of the first embodiment. 4 and the processes shown in FIGS. 5 and 6 are the same as those in the first embodiment, and thus the flowchart and the detailed description of the second embodiment are omitted.

(Operation of Example 2)
In the food sample sorting apparatus 1 of Example 2 having the above-described configuration, the reflected / scattered light is separated into the P-polarized component and the S-polarized component by using the polarizing beam splitter 8a ′ as the polarizing optical element, respectively. The P ′ direction component that is received and contains the reflected light from the water is not used for discrimination, the influence of the reflected light from the water is small, and the S ′ direction component due to the scattered light from the object S itself is used for the discrimination. Therefore, the foreign matter discrimination accuracy can be improved as compared with the conventional configuration that is affected by water.
Further, in the food sample sorting apparatus 1 of the second embodiment, the polarizing beam splitter 8a ′ is arranged, and the inclination angle θ in the P ′ direction is derived before starting the measurement of the foreign matter. Even if the position is slightly shifted at the time of installation, only the inclination angle θ changes, and the influence on the detection of foreign matter is reduced. That is, in the configuration of the first embodiment, it is necessary to accurately install and adjust the position and orientation of the polarizing filter 8a so that the same polarization direction component as that of the linearly polarized incident laser light by water reflection is attenuated and eliminated. However, in the second embodiment, such trouble can be omitted, and the determination can be performed without being affected by the error of the position and orientation at the time of installation.
In addition, the second embodiment has the same operations and effects as the first embodiment.

(Experimental example)
FIG. 10 is an explanatory diagram of the measurement results of the spectral characteristics of raisins and stems, and is a graph in which the horizontal axis represents wavelength and the vertical axis represents reflectance.
Next, an experiment was performed to confirm the effect of the present invention.
In Experimental Examples 1 to 8, raisins as the test object S were targeted, and stems (stems) as foreign matters to be mixed were targeted. FIG. 10 shows the measurement results of the spectral characteristics of raisins and stems.
As shown in FIG. 10, in the raisins, it was confirmed that the difference in reflectance was observed at a wavelength of 600 nm or more with respect to the stem, and in particular, the difference was increased at 800 nm or more. Therefore, in the following experimental examples, experiments were performed by selecting red laser light having a wavelength of 635 nm or near infrared light having a wavelength of 830 nm.

FIG. 11 is an explanatory diagram of the apparatus used in Comparative Example 1 and Experimental Example 1.
In FIG. 11, in the experimental example, the reflected / scattered light 31 from the object S to be inspected is separated by the half mirror 32, and the reflected / scattered light 31 a transmitted through the half mirror 32 passes through the polarization filter 33 and is photomultiplied. Detection is performed by a light receiving element 34 for an experimental example constituted by a tube. Then, the reflected / scattered light 31b reflected by the half mirror 32 is detected by the light receiving element 36 for the comparative example configured by a photomultiplier tube without passing through the polarizing filter. In this experimental example, the polarizing filter 33 is arranged so that a polarized light component perpendicular to the polarization direction of the irradiated laser light is transmitted.

(Comparative Example 1)
In Comparative Example 1, an experiment was conducted by using a 635-nm red laser beam and using a light receiving element 36 for a comparative example in which no polarizing filter is installed. In Comparative Example 1, dry raisins were used as the test object S.
(Experimental example 1)
Experimental Example 1 is the same as Comparative Example 1 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 1 and Experimental Example 1 are shown in FIG.

12 is an explanatory diagram of the experimental results of Comparative Example 1 and Experimental Example 1. FIG. 12A is a graph of the experimental results of Comparative Example 1, and FIG. 12B is a graph of the experimental results of Experimental Example 1.
The graph of the experimental results shown in FIG. 12 is a graph in the three-axis direction, the value of the output signal is taken on the vertical axis (height direction), the position in the drop direction is taken on the width axis, and the axis in the depth direction is taken. The position in the scanning direction was taken. In the graph shown in FIG. 12, the evaluation was performed based on the signal elongation with respect to the reference signal. The reference signal is a detection signal of reflected / scattered light from the background. In the experimental example, in order to facilitate the setting of the threshold, basically, in the case of a good product raisins, near infrared light (NIR) above the graph with respect to the reference signal when visible light such as a red laser is irradiated. : Near Infrared) The background is adjusted in advance so that a signal appears below during irradiation. Note that, in the graphs in the directions of the three axes in the following description, the manner of taking each axis, the background adjustment, and the like are performed in the same manner.
In addition, about FIGS. 12-19, it is going to submit by attaching a color drawing as a reference drawing after an application and attaching to an above-mentioned application.

  In FIG. 12A, it was confirmed that the comparative example 1 received reflected / scattered light that was strong overall with respect to the reference signal. On the other hand, in FIG. 12B, in Experimental Example 1, it was confirmed that strong reflected / scattered light was received in some places with respect to the reference signal. Comparing Experimental Example 1 with Comparative Example 1, the presence or absence of the polarizing filter 33 attenuates the intensity level of reflected / scattered light as a whole, and the raisins can be confirmed by a signal that maintains a strong intensity without being attenuated. It is.

(Comparative Example 2)
In Comparative Example 2, an experiment was performed in the same experimental apparatus as in Comparative Example 1, using a near-infrared (NIR) laser beam of 830 nm and a light receiving element 36 for a comparative example in which no polarizing filter was installed. Went. In Comparative Example 2, as in Comparative Example 1, dry raisins were used as the test object S.
(Experimental example 2)
Experimental Example 2 is the same as Comparative Example 2 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 2 and Experimental Example 2 are shown in FIG.

13 is an explanatory diagram of the experimental results of Comparative Example 2 and Experimental Example 2, FIG. 13A is a graph of the experimental results of Comparative Example 2, and FIG. 13B is a graph of the experimental results of Experimental Example 2.
In FIG. 13A, in Comparative Example 2, the reflected / scattered light intensity can be confirmed vertically with respect to the reference signal.
In FIG. 13B, it can be seen that, in Experimental Example 2, the intensity of reflected / scattered light is generally smaller than that of Comparative Example 2 in FIG. 13A, and the reflected / scattered light intensity of raisins with respect to the reference signal is reduced. Is low.
Therefore, from the results of Experimental Examples 1 and 2 and Comparative Examples 1 and 2, by installing the polarizing filter 33 in the dried raisins, regardless of the wavelength, reflected light or strong scattered light due to specular reflection and surface irregularities It was confirmed that it can be attenuated.

(Comparative Example 3)
In Comparative Example 3, an experiment was performed in the same experimental apparatus as in Comparative Example 1 using a 635-nm red laser beam and using a light receiving element 36 for a comparative example in which no polarizing filter was installed. In Comparative Example 3, raisins wet with water were used as the test object S.
(Experimental example 3)
Experimental Example 3 is the same as Comparative Example 3 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 3 and Experimental Example 3 are shown in FIG.

14 is an explanatory diagram of the experimental results of Comparative Example 3 and Experimental Example 3, FIG. 14A is a graph of the experimental results of Comparative Example 3, and FIG. 14B is a graph of the experimental results of Experimental Example 3.
14A, in Comparative Example 3, it was confirmed that strong reflected / scattered light was detected as a whole with respect to the reference signal.
In FIG. 14B, strong reflected / scattered light can be confirmed with respect to the reference signal in Experimental Example 3, but it was confirmed that the signal was attenuated as compared with Comparative Example 3 in FIG. 14A.

(Comparative Example 4)
In Comparative Example 4, an experiment was performed in the same experimental apparatus as Comparative Example 1, using a near-infrared (NIR) laser beam of 830 nm and a light receiving element 36 for a comparative example in which no polarizing filter was installed. Went. In Comparative Example 4, as in Comparative Example 3, raisins that were washed with water and wetted with water were used as the test object S.
(Experimental example 4)
Experimental Example 4 is the same as Comparative Example 4 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 4 and Experimental Example 4 are shown in FIG.

15 is an explanatory diagram of the experimental results of Comparative Example 4 and Experimental Example 4, FIG. 15A is a graph of the experimental results of Comparative Example 4, and FIG. 15B is a graph of the experimental results of Experimental Example 4.
In FIG. 15A, in Comparative Example 4, a strong reflected / scattered light intensity can be confirmed at one location with respect to the reference signal. This is considered to be reflected light from the water film. Therefore, conventionally, erroneous detection has occurred due to the reflected light from the water film. The raisins were confirmed to be output to the lower side (lower voltage value side) with respect to the reference signal.
In FIG. 15B, it was confirmed that in Experimental Example 4, there was no apparently strong reflected / scattered light with respect to the reference signal as compared with Comparative Example 4 in FIG. 15A. Also in Experimental Example 4, raisins are output to the lower side (lower voltage value side) with respect to the reference signal.
Therefore, from the results of Experimental Examples 3 and 4 and Comparative Examples 3 and 4, it was confirmed that the reflection / scattered light by the water film attached to the raisins surface can be attenuated by installing the polarizing filter 33.

(Comparative Example 5)
In Comparative Example 5, an experiment was performed in the same experimental apparatus as in Comparative Example 1, using a red laser beam of 635 nm and using a light receiving element 36 for a comparative example in which no polarizing filter was installed. In Comparative Example 5, a dry stem (stem) as an example of a foreign object was used as the inspection object S.
(Experimental example 5)
Experimental Example 5 is the same as Comparative Example 5 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 5 and Experimental Example 5 are shown in FIG.

16 is an explanatory diagram of the experimental results of Comparative Example 5 and Experimental Example 5, FIG. 16A is a graph of the experimental results of Comparative Example 5, and FIG. 16B is a graph of the experimental results of Experimental Example 5.
16A, in Comparative Example 5, it was confirmed that strong reflected / scattered light was detected as a whole with respect to the reference signal.
16B, in Experimental Example 5, the signal is attenuated as compared with Comparative Example 5 in FIG. 16A, but a relatively strong output value of 2 [V] or more is maintained with respect to the reference signal. It was confirmed.

(Comparative Example 6)
In Comparative Example 6, an experiment similar to that in Comparative Example 1 was performed using a near-infrared (NIR) laser beam of 830 nm and a light receiving element 36 for a comparative example in which no polarizing filter was installed. Went. In Comparative Example 6, as in Comparative Example 5, a dry stem was used as the inspection object S.
(Experimental example 6)
Experimental Example 6 is the same as Comparative Example 6 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 6 and Experimental Example 6 are shown in FIG.

17 is an explanatory diagram of the experimental results of Comparative Example 6 and Experimental Example 6, FIG. 17A is a graph of the experimental results of Comparative Example 6, and FIG. 17B is a graph of the experimental results of Experimental Example 6.
In FIG. 17A and FIG. 17B, the experimental example 6 is attenuated as a whole as compared with the comparative example 6, but the intensity of the reflected / scattered light of the stem is about 2 “V” even when the polarizing filter 33 is installed. It was confirmed that the above strength was maintained.
Therefore, from the results of Experimental Examples 5 and 6 and Comparative Examples 5 and 6, even if the polarizing filter 33 is installed in the stem, a relatively strong output value of 2 [V] or more is output above the reference signal. It was confirmed that

(Comparative Example 7)
In Comparative Example 7, an experiment was performed in the same experimental apparatus as in Comparative Example 1, using a 635-nm red laser beam and using a light receiving element 36 for a comparative example in which no polarizing filter was installed. Further, in Comparative Example 7, a stem wet with water as an example of a foreign object was used as the inspection object S.
(Experimental example 7)
Experimental Example 7 is the same as Comparative Example 7 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 7 and Experimental Example 7 are shown in FIG.

18 is an explanatory diagram of the experimental results of Comparative Example 7 and Experimental Example 7, FIG. 18A is a graph of the experimental results of Comparative Example 7, and FIG. 18B is a graph of the experimental results of Experimental Example 7.
18A, in Comparative Example 7, it was confirmed that strong reflected / scattered light was detected as a whole with respect to the reference signal.
18B, in Experimental Example 7, the signal is attenuated as compared with Comparative Example 7 in FIG. 18A, but a relatively strong output value of 3 [V] or more is maintained with respect to the reference signal. It was confirmed.

(Comparative Example 8)
In comparative example 8, in the same experimental apparatus as in comparative example 1, an experiment was performed using a near-infrared (NIR) laser beam of 830 nm and a light receiving element 36 for comparative example in which no polarizing filter was installed. Went. In Comparative Example 8, similarly to Comparative Example 7, a stem wet with water was used as the object S to be inspected.
(Experimental example 8)
Experimental Example 8 is the same as Comparative Example 8 except that the experiment was performed using the light receiving element 34 for the experimental example.
The results of Comparative Example 8 and Experimental Example 8 are shown in FIG.

19 is an explanatory diagram of the experimental results of Comparative Example 8 and Experimental Example 8, FIG. 19A is a graph of the experimental results of Comparative Example 8, and FIG. 19B is a graph of the experimental results of Experimental Example 8.
In FIG. 19A and FIG. 19B, in Experimental Example 8, as compared with Comparative Example 8, overall attenuation is achieved. However, as in Experimental Example 6, even when the polarizing filter 33 is installed, the reflected / scattered light of the stem is It was confirmed that the strength maintained a strength of about 2 “V” or more.
Therefore, from the results of Experimental Examples 5 to 8 and Comparative Examples 5 to 8, in the case of the stem, regardless of the surface state, 2 [V] or more above the reference signal even if the polarizing filter 33 is installed It was confirmed that a relatively strong output value was output.

Therefore, from the results of Experimental Examples 1 to 8 and Comparative Examples 1 to 8, by disposing the polarizing filter 33, the reflected / scattered light of water is attenuated and the reflected / scattered light from the raisins and stems is received. It was confirmed that it was possible to reduce false detections caused by the influence of water. As a result, it became possible to inspect and sort a specimen wet with water with high accuracy.
From the results of Experimental Examples 1 to 8 and Comparative Examples 1 to 8, when selecting raisins and stems, the use of 830 nm NIR laser light has a clear potential difference in the intensity of reflected / scattered light. As a result of the confirmation, it was confirmed that this was advantageous compared to the case of using a red laser beam of 635 nm.

That is, when a 635 nm laser beam is used, the signal is a positive signal regardless of whether the raisins and stems are dry or wet with respect to the reference signal, and whether or not the polarizing filter 33 is installed. The threshold can be set, and raisins and stems can be discriminated. However, occasionally, strong reflected / scattered light exceeding the discrimination threshold may be received. On the other hand, when an NIR laser beam of 830 nm is used, the raisins are signals in the minus direction and the stems are signals in the plus direction with respect to the reference signal, so there is a clear difference and it can be said that the wavelength is suitable for discrimination. .
However, from Experimental Examples 1-8, especially Experimental Example 4 and Comparative Example 4, when unnecessary reflection that affects discrimination, such as partial specular reflection of raisins or water film reflection of wet raisins, becomes strong. Even in the raisins, a positive signal appears and misidentification occurs.
Therefore, next, by adjusting the rotation angle of the polarizing filter, the stem remains in the same positive signal as when it was dried, reducing unwanted reflections due to the water film attached to the raisins and the unevenness of the raisins surface. Thus, an experiment was conducted to confirm that it is possible to attenuate or erase a positive signal that exceeds the discrimination threshold and leads to erroneous discrimination.

FIG. 20 is an explanatory diagram of an experimental apparatus used in Experimental Example 9.
(Experimental example 9)
In Experimental Example 9, as shown in FIG. 20, the laser light 41a emitted from the linearly polarized laser light source 41 to the object S is arranged at a position of 45 ° and rotatable within a range of ± 90 °. The polarizing filter 42 was installed, and the reflected / scattered light that passed through the polarizing filter 42 was detected by the light receiving element 43.
In Experimental Example 9, 635 nm red laser light was used, and the rotation angle of the polarizing filter 42 was controlled in a range of −90 ° to + 90 ° in steps of 10 °, and each experiment was performed. Further, as the inspected object S, dry raisins, raisins wet with water, dry stems, and stems wet with water were targeted.
FIG. 21 shows the experimental results.

FIG. 21 is an explanatory diagram of the experimental results of Experimental Example 9. FIG. 21A is a graph of the intensity of the detected reflected / scattered light, and FIG. 21B is the intensity of the reflected / scattered light of FIG. It is a graph normalized as 1.
In the graph of FIG. 21, the horizontal axis represents the rotation angle, and the vertical axis represents the intensity of reflected / scattered light.
In FIG. 21, in the dry raisins and wet raisins, the rotation angle is 0 °, that is, 0 ° when the rotation angle is 90 ° with respect to the intensity of the laser beam having the same polarization direction as the irradiated laser beam 41a. The degree of depolarization is low because the intensity of reflected / scattered light is lower than the intensity of light, whereas the decrease rate of reflected / scattered light intensity is lower for dry stems and wet stems than for raisins. As a result, it was confirmed that the degree of depolarization was higher than that of raisins. That is, as shown in FIG. 21B, the rotation angle is close to 90 °, and the normalized intensity, that is, the intensity ratio, is used, so that accurate determination of raisins can be made even with 635 nm red laser light. It was confirmed that it was possible.

(Experimental example 10)
In Experimental Example 10, the experiment was performed in the same manner as in Experimental Example 9, except that 830 nm NIR laser light was used.
The experimental results are shown in FIG.

22 is an explanatory diagram of the experimental results of Experimental Example 10, FIG. 22A is a graph of the intensity of the detected reflected / scattered light, and FIG. 22B is the intensity of the reflected / scattered light data of FIG. It is a graph normalized as 1.
In FIG. 22, also in Experimental Example 10, as in Experimental Example 9, with a dry raisins and wet raisins, the rotation angle is 0 °, that is, with respect to the intensity of the laser light in the same polarization direction as the irradiated laser light 41a. Thus, when the rotation angle is 90 °, the intensity of reflected / scattered light is lower than the intensity at 0 °, so the degree of depolarization is low. It was confirmed that the degree of depolarization was high because the scattered light intensity was not significantly different from the intensity at 0 °.

That is, as shown in FIG. 22B, the rotation angle is close to 90 ° and the normalized intensity, that is, the intensity ratio is used, so that accurate determination of raisins can be made even with NIR laser light of 830 nm. It was confirmed that it was possible. In addition, as shown in FIG. 21B and FIG. 22B, it was also confirmed that sufficiently accurate determination was possible even when the rotation angle was about 45 ° to 60 °. That is, it was confirmed that inspection and identification were possible by receiving reflected / scattered light having a polarization component different from the polarization component (0 °) of the irradiation laser beam.
In FIG. 22A, in the case of 830 nm laser light, the rotation angle is set to an angle close to 90 °, so that the intensity ratio is not used and the raisins and stems are used even if the intensity values are used as they are. It was confirmed that it was possible to identify.

(Experimental example 11)
Next, an experiment was actually performed using the apparatus of Example 1. In Experimental Example 11, using the apparatus of Example 1, laser beams of 635 nm and 830 nm are used, and the polarizing filter 8a is transmitted so that a polarization component perpendicular (90 °) to the polarization component of the laser light is transmitted. The installation was conducted. In the experiment, about 3 kg of raisins added with about 50 [cc] of water was used, and data was collected three times.
(Comparative Example 11)
In Comparative Example 11, an experiment was performed under the same conditions as in Experimental Example 11 except that no polarizing filter was disposed.
The experimental results are shown in FIG.

FIG. 23 is an explanatory diagram of experimental results of Experimental Example 11 and Comparative Example 11, FIG. 23A is an explanatory diagram of experimental results of Comparative Example 11, and FIG. 23B is an explanatory diagram of experimental results of Experimental Example 11.
In FIG. 23, in Comparative Example 11 in which the polarizing filter is not disposed, the false detection ratios are 27%, 19%, and 30%, whereas in Experimental Example 11 in which the polarizing filter is disposed, the false detection ratio is. It was 9%, 6%, and 6%, and it was confirmed that the false detection rate decreased to 10% or less. That is, as can be seen from the graph shown in FIG. 12, even in the dry raisins, depending on the influence of the surface shape of the raisins (surface irregularities), in some cases, reflected / scattered light stronger than the discrimination threshold is received, and erroneous detection is detected. Although it was the cause, the number of false positives was reduced by manipulating and adjusting the polarization direction as in the case of raisins wet with water. This is because the scattered light from the raisins is depolarized, but the light reflected by the water film and surface irregularities is not easily depolarized.
Therefore, it was found that by using the polarizing filter, the reflected light due to water on the raisins surface can be attenuated, and the detection accuracy can be increased.

(Experimental example 12)
FIG. 24 is an experimental apparatus diagram of an angle distribution of scattered light from a sample at the time of laser light irradiation in Experimental Example 12.
Next, an experiment was conducted on the distribution of transmitted light, reflected light, and scattered light of the laser light irradiated on the object S to be inspected, that is, in which angle direction the transmitted light, reflected light, and scattered light are detected. .
In FIG. 24, a laser beam 51a having a wavelength of 830 nm is applied to the object S to be inspected. Inspected object S of Experimental Example 12 is sandwiched between two glass plates having a thickness of 1 mm in order to make the surface shape (unevenness) uniform, and is compressed until the distance between the glass plates becomes 1 mm, and the surface is made as much as possible. After flattening, the laser beam 51a was irradiated from a direction of an angle of 45 ° using a glass plate on the laser beam irradiation side removed. The reflected / transmitted / scattered light from the object S to be inspected was received by the photomultiplier tube 55 after passing through the polarizing filter 54.

The output of the photomultiplier tube 55 was converted into a voltage and then amplified by an amplifier 56 by about 20 times to obtain the light intensity at that point. The photomultiplier tube 55 was rotated clockwise by 10 °, and the measurement was performed with the polarizing filter 54 at 90 ° perpendicular to the polarization direction of the irradiation laser beam 51a at each position.
(Comparative Example 12)
In Comparative Example 12, the experiment was performed in the same manner as in Experimental Example 12 except that the polarizing filter 54 was not installed.
The experimental results are shown in FIGS.

FIG. 25 is an explanatory diagram of the experimental results of Comparative Example 12, and is a graph of the experimental results of irradiating raisins and stems wet with water to a 830 nm laser beam without installing a polarizing filter.
FIG. 26 is an explanatory diagram of an experimental result of Experimental Example 12, and is a graph of an experimental result in which a raisin and a stem wet with water with a polarizing filter installed are irradiated with 830 nm laser light.
Note that the graphs of FIGS. 25 and 26 take the rotational position in the circumferential direction and take the light intensity in the radial direction. 25 and 26, the raisins experimental results are indicated by black circles, and the stem experimental results are indicated by white crosses.

In FIG. 25, in Comparative Example 12 in which no polarizing filter is installed, the threshold value for discriminating between raisins and stems in the reflected / backscattered light is set to the photomultiplier tube 55 when the raisins wet with good water. Has been exceeded in the 270 ° direction where it is arranged. This is the reflected light from the water film, which is the cause of non-defective product detection.
26, in Experimental Example 12 in which the polarization filter is installed so as to receive only the vertical component with respect to the polarization direction of the irradiation laser light, the water observed in the 270 ° direction of FIG. 25 in the reflected / backscattered light. It can be seen that the strong reflected / scattered light from the film is attenuated and distributed without exceeding the threshold for distinguishing raisins and stems.
Therefore, from the results shown in FIGS. 25 and 26, by installing the polarizing filter 54, it is possible to reduce false detection of non-defective raisins wet with water.

(Experimental example 13)
FIG. 27 is an explanatory diagram of the measurement results of the spectral characteristics of walnuts, shells and astringent skin corresponding to FIG. 10 of Experimental Examples 1 to 8, where the horizontal axis represents wavelength and the vertical axis represents reflectance. is there.
Next, an experiment was conducted on a walnut as an example of an inspection object different from the raisins. The experiment was conducted on walnut shells and astringent skin (hereinafter sometimes referred to as “partition walls”) instead of stems (grape stalks), which are foreign substances to raisins.
First, the spectral characteristics of walnuts, shells and astringent skin were measured. The measurement results are shown in FIG.
From the results shown in FIG. 27, in the case of walnuts, the “shell” and “buckle skin (partition wall)” of walnuts are spectroscopic in near infrared light having a wavelength longer than 800 nm or visible light in the range of 500 nm to 800 nm. It was found that there was a difference in characteristics. Therefore, for the selection of walnuts, an experiment was performed using a green laser beam of 532 nm, a red laser beam of 635 nm, and a near infrared light of 830 nm.

FIG. 28 is an explanatory diagram of an experimental apparatus for an experiment on the scattered light angle distribution from the sample during the laser light irradiation of Experimental Example 13.
Next, in the same manner as in Experimental Example 12, experiments were performed on the distribution of transmitted light, reflected light, and scattered light of laser light with respect to walnuts.
In FIG. 28, a first dichroic in which a laser beam 61a having a wavelength of 830 nm from the first laser 61 and a laser beam 62a having a wavelength of 635 nm from the second laser 62 reflect red light and transmit infrared light. The mirror 64 makes the same axis, and the 532 nm laser light 63a from the third laser 63 is made the same axis by the second dichroic mirror 65 that reflects green and transmits infrared and red. And each to-be-inspected object S was irradiated from the direction of 45 degrees of each laser beam 61a-63a made on the same axis | shaft. The reflected / transmitted / scattered light from the inspection object S was received by the photomultiplier tube 67.

Note that the output of the photomultiplier tube 67 was converted to a voltage and amplified by an amplifier 68 approximately 20 times in the same manner as in Experimental Example 12 to obtain the light intensity at that point.
In Experimental Example 13, the backscattered light was measured. That is, the measurement was performed by rotating the rotation position clockwise by 10 ° in the range of 220 ° to 330 °.
The experimental results are shown in FIGS.

FIG. 29 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnuts, shells and partition walls with a laser beam of 532 nm.
FIG. 30 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnut nuts, shells, and partition walls with 635 nm laser light.
FIG. 31 is an explanatory diagram of the experimental results of Experimental Example 13, and is a graph of the experimental results of walnut nuts, shells and partition walls with 830 nm laser light.
Note that the graphs of FIGS. 29 to 31 take the rotational position in the circumferential direction and take the light intensity in the radial direction, similarly to FIGS. 25 to 28. 29 to 31, the experimental results of walnuts are indicated by asterisks, the experimental results of partition walls are indicated by black circles, and the experimental results of shells are indicated by white squares.

In FIG. 29, when the laser beam 63a of 532 nm is used, the distribution is slightly biased in the direction of 270 ° which is the reflection angle direction as a whole.
In contrast to walnuts, it is difficult to sort shells because the strength is the same at 330 °. However, in contrast to walnuts, separation of bulkheads scatters both walnuts and bulkheads. It can be seen that the light intensity is isotropically distributed and the contrast is clear.

In FIG. 30, when the 635 nm laser beam 62a is used, the distribution is slightly biased in the direction of 270 °, which is the reflection angle direction, as in FIG.
As with the case of FIG. 29, it is difficult to sort the shells against the walnuts because the strength is the same at 270 °, but the separation of the partition walls against the walnuts is difficult. It can be seen that both the walnuts and the partition walls are possible because the scattered light intensity is isotropically distributed and the contrast is clear. However, compared with the case of FIG. 29, the isotropy of the scattered light distribution is slightly inferior for the real and the partition walls (a slightly strong reflected / scattered light is confirmed at 260 ° in FIG. 30 and the threshold for selection is set). It will be difficult to). Therefore, it can be seen that the laser beam 63a of 532 nm is more advantageous when sorting the walnut fruit and the partition wall.

In FIG. 31, when the 830 nm laser beam 61a is used, it is difficult to select the partition walls with respect to the walnuts, because the intensity is the same value at 280 °. Since the light intensity is reversed, the upper threshold and the lower threshold cannot be determined, and the determination is difficult.
On the other hand, for the walnuts, it can be seen that the shell can be sorted because the difference in scattered light intensity can be confirmed between the two and the contrast is clear.
From the results of FIGS. 29 to 31, in Experimental Example 13, it is possible to select the partition walls with respect to walnuts at both wavelengths of 532 nm and 635 nm, but 532 nm is slightly more advantageous. all right. It was also found that walnut shells can be selected by using 830 nm laser light.
Since walnuts are agricultural products and foods as well as raisins, it may be washed with water. In that case, as with raisins, by receiving only a specific polarized component, By reducing the reflected light, highly accurate inspection and sorting becomes possible.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible.
For example, in the above-described embodiment, the food sample is exemplified as the object to be inspected. However, the present invention is not limited to the food sample. Can be determined.

  Moreover, in the said Example, although the structure which provides several laser LS1-LSn and light receiving element PD1-PDn, PD1'-PDn ', PD1 "-PDn" was illustrated, it is not limited to this structure, A laser and a light receiving element The number can be any number according to the design and specifications, the type of the object to be inspected, etc., or can be only one.

  Furthermore, in the said Example, although it selected based on the intensity | strength of the reflected light of the laser beam of two wavelengths, and an intensity ratio, it is not limited to this structure, The kind of food sample S to be used, and the required precision Depending on the above, it is also possible to make a discrimination only by intensity, to make a discrimination only by intensity ratio, or to make a discrimination by intensity difference. Further, although the determination is made based on two laser beams, it is possible to use only one, or use the intensity, intensity ratio, intensity difference, etc. of laser beams having three or four or more wavelengths.

  In the above embodiment, the foreign matter is determined as non-defective when all the intensity and intensity ratio of the two laser beams are within the range from the upper limit value to the lower limit value. For example, if the intensity ratio is not used and the intensity of one of the two laser lights falls between the upper limit value and the lower limit value, it is determined as a non-defective product, or the intensity of the two laser lights falls from the upper limit value to the lower limit value. Even if it is not within the range, if the intensity ratio is between the upper limit and the lower limit, it is determined that the product is good. It is possible to change according to the kind of.

Furthermore, although the size filter process is executed in the above-described embodiment, the size filter process can be omitted. That is, it is also possible to configure so that air is ejected corresponding to a foreign object pixel each time one determined foreign object pixel (foreign substance signal) is detected.
In the above-described embodiment, the size filter process is configured to perform removal when the number of continuous foreign matter pixels is 18 or more. However, the present invention is not limited to this configuration. For example, 2 (pixels) × 2 ( It is also possible to adopt a configuration in which, when a foreign pixel area having a predetermined size such as (pixel), 3 × 3, 2 × 4, or the like exists, that area is determined as a foreign substance.

  Furthermore, in the embodiment, in the size filter process, the process is performed based on the history data for 15 lines. However, the present invention is not limited to this configuration, and the size and resolution of the object to be inspected, the required accuracy, etc. Accordingly, it is also possible to employ history data in an arbitrary area having more or less than 15 lines. In addition, the size filter process is executed every time data for one line is updated. However, the size filter process is not limited to this configuration. For example, after the data for 15 lines is accumulated and the size filter process is executed, the data The size filter processing is performed each time data for a predetermined time period is accumulated, such as when the data for the next 15 lines is accumulated and the next size filter processing is executed after the data for the next 15 lines is accumulated. It can also be configured to execute.

Further, in the above-described embodiment, a configuration for performing discrimination based on a component orthogonal to the linearly polarized laser beam is exemplified, and it is desirable to adopt this configuration. However, the required accuracy, when installing the device and each member It is possible to make a determination based on a component in an arbitrary polarization direction that is different from the polarization direction of linearly polarized light, instead of a component orthogonal to each other, depending on the accuracy and the like. In this case, it is desirable that the inclined direction is close to the orthogonal direction.
In the above embodiment, air is blown out to remove foreign matters. However, the present invention is not limited to this configuration, and a configuration for sucking air is used. It is also possible to remove by an arbitrary removal method such as a configuration of removing by flying.
In the above-described embodiment, the laser beam irradiated to the object S to be inspected using the first polarizing optical element 7a is a linearly polarized laser beam, but a laser capable of emitting a linearly polarized laser beam is used. In this case, the polarizing optical element 7a can be omitted.

  Furthermore, in the above embodiment, when irradiating laser light to the foreign matter contamination determination area, scanning was performed using a rotating polygon mirror, but not limited to this configuration, using a beam expander, an optical lens, or the like, It is also possible to configure so that the width of the foreign matter mixing determination area is irradiated with laser light.

Furthermore, regarding foreign matter removal, in this embodiment, one foreign matter removing device 13 (air nozzle) is disposed in the drop conveyance path 4 to remove the foreign matter to be removed. However, the present invention is not limited to this configuration. If the trajectory is likely to change and the object to be inspected determined in the foreign matter mixing determination area 5 is difficult to drop to a stable position with respect to the air nozzle, the number of air nozzles that blow air in the main scanning direction is set. It is also possible to increase the ejection width and increase the ejection width, or to blow air from a plurality of directions so that foreign matter can be reliably removed.
Also, in the sub-scanning direction, air is ejected for a time corresponding to the foreign object to be removed, but taking into account variations in the drop time, the air ejection time can be changed and set longer than the size of the foreign object, or in the sub-scanning direction. It is also possible to arrange a plurality of foreign matter removing devices along the side, and the foreign matter can be reliably removed.

  The present invention can be suitably used for pre-shipment inspection and acceptance inspection for various materials such as food.

DESCRIPTION OF SYMBOLS 1 ... Food sample sorter 2 ... Sample conveyance member 3 ... Vibrating device 4 ... Falling conveyance path 5 ... Foreign substance mixing determination area | region 6 ... Foreign substance mixing determination apparatus 7 ... Laser light source apparatus 7a ... 1st polarizing optical element 8 ... Light receiver 8a , 8a '... second polarization optical element 10 ... light intensity measuring device 11 ... arithmetic processing unit 11A ... foreign matter contamination determination means 11A1 ... filter processing means 11A2 ... foreign matter contamination discrimination value storage means 11A3 ... foreign matter pixel discrimination means 11A4 ... discrimination history Data storage means 11A5 ... Determination result update means 11A6 ... Size filter processing means 11A6a ... Foreign substance region extraction means 11A6b ... Area discrimination value storage means 11A6c ... Foreign substance signal output means 11A7 ... Determination intensity calculation means 11A7a ... Linear polarization component projection angle storage means 11A7b: Polarization direction calculation means 11A7c ... Orthogonal component calculation means 12 ... Removal device control circuit 13 ... Foreign matter removal Position 14 ... Foreign matter collection path 15 ... Foreign matter collection container 16 ... Downstream transport devices FL1-FLn, FL1'-FLn ', FL1 "-FLn" ... Wavelength selection filter L1 ... Foreign matter mixing determination upper limit values LS1-LSn ... Laser PD1- PDn, PD1 'to PDn', PD1 "to PDn" ... light receiving element PM ... polygon mirror S ... inspection object

Claims (4)

An irradiation light source system for irradiating a test object with a laser beam having a specific single wavelength and linearly polarized light;
Reflected / scattered light including reflected / scattered light including a direction component different from the polarization direction of the laser light by the inspection object itself and reflected light having the same polarization direction as the laser light due to water on the surface of the inspection object A light receiving optical system having a light receiving element that receives reflected / scattered light including at least a polarization component in a direction different from the polarization direction of the laser light in the light;
Foreign matter mixing determination means for determining whether the object to be inspected is a foreign matter based on a polarization component in a direction different from the polarization direction of the laser light of the received reflected / scattered light,
A foreign matter contamination determination device comprising: A polarizing optical element that is disposed on the optical path of the reflected / scattered light and that transmits light having a polarization component in a direction orthogonal to the polarization direction of the laser light included in the reflected / scattered light, and has passed through the polarizing optical element The light receiving optical system having the light receiving element for receiving light,
The foreign matter contamination determination apparatus according to claim 1, comprising: A polarizing optical element disposed on an optical path of the reflected / scattered light and separating the reflected / scattered light into components of a first polarization direction and a second polarization direction orthogonal to each other; and light in the first polarization direction A light receiving optical system comprising: a first light receiving element that receives light and a second light receiving element that receives light in the second polarization direction; and
A direction orthogonal to the polarization direction of the laser light based on the light in the first polarization direction, the light in the second polarization direction, and the polarization direction of the laser light irradiated on the object to be inspected. Orthogonal component computing means for computing the polarization component of
The foreign substance contamination determination means for determining whether the object to be inspected is a foreign substance based on a polarization component in a direction orthogonal to the polarization direction of the laser light calculated by the orthogonal component calculation means;
The foreign matter contamination determination apparatus according to claim 1, comprising: Irradiate a test object with a specific single wavelength and linearly polarized laser beam,
Reflected / scattered light including reflected / scattered light including a direction component different from the polarization direction of the laser light by the inspection object itself and reflected light having the same polarization direction as the laser light due to water on the surface of the inspection object Receiving reflected / scattered light containing at least a polarization component in a direction different from the polarization direction of the laser light in the light,
A foreign matter contamination determination method, comprising: determining whether the object to be inspected is a foreign matter based on a polarization component of the received reflected / scattered light in a direction different from the polarization direction of the laser light.