JP2017122705A - Calculation method, determination method, selection method, and selection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination method capable of accurately determining sorts of materials constituting objects to be inspected even when three or more sorts of objects to be inspected are included in a plurality of objects to be inspected.SOLUTION: A determination method for determining sorts of materials constituting an object to be inspected includes: a step for irradiating the object to be inspected with X rays and detecting transmission intensity of low energy X rays transmitted through the object to be inspected and transmission intensity of high energy X rays transmitted through the object to be inspected; a step for calculating relation between a differential value determining the transmission intensity of low energy X rays and the transmission intensity of high energy X rays as a weighted difference and a weight coefficient to be used for the weighted difference; and a step for determining sorts of materials constituting the object to be inspected on the basis of a plurality of relations respectively corresponding to a plurality of reference objects of which the sorts of materials are known and are mutually different and relation corresponding to the object to be inspected.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a calculation method, a determination method, a sorting method, and a sorting apparatus, and in particular, a calculation method used for determining the type of material constituting an inspection object, a determination method using the calculation method, and an inspection object. The present invention relates to a sorting method and a sorting apparatus.

  Conventionally, foreign substances inspection using transmitted X-rays has been performed in various industries such as the food industry and the pharmaceutical industry. In this method, an object is irradiated with X-rays, and foreign matter is detected based on a difference in transmission intensity (absorption magnitude) of the X-rays transmitted through the object. The X-ray transmission intensity depends on the material, thickness and density of the object, the type of element constituting the object, the concentration of the element, and the like.

  Here, when the influence on the X-ray transmission intensity due to the difference in element concentration, thickness, and density is smaller than the influence on the X-ray transmission intensity due to the kind of element, by referring to the X-ray transmission intensity, It is possible to identify an object containing the element. However, when the influence of the former is larger than the influence of the latter, it is difficult to specify an object including the target element.

  Therefore, a method called an energy subtraction method is known as a method for determining a material in consideration of the thickness of an object. This method measures the transmission intensity of X-rays of two different energies (low energy and high energy), separates the different component images by logarithmically transforming them and performing weighted difference processing using parameters. It is a method to do. However, in this method, since the work of appropriately setting parameters may be delicate and troublesome, for example, the following technique has been proposed.

  Japanese Patent Laying-Open No. 2010-91483 (Patent Document 1) obtains a separation matrix by applying independent component analysis to a low-energy and high-energy equivalent thickness image pair generated from a dual energy X-ray image. Discloses a method for setting a weighting parameter for differential processing using two separation vectors.

JP 2010-91483 A

  In Patent Literature 1, an independent component analysis is applied to an equivalent thickness image pair to obtain a separation matrix, but three or more types of substances cannot be distinguished based on two transmission X-ray images. That is, the types of substances (materials) that constitute the inspected object that can be determined are limited to two. Therefore, when there is a possibility that three or more types of inspection objects are included in a plurality of inspection objects, there is a problem that the type of material constituting the inspection object cannot be accurately determined. It was.

  This indication is made in order to solve the above-mentioned problem, and the purpose of a certain situation is a case where three or more kinds of inspection objects are included in a plurality of inspection objects. To provide a calculation method used for accurately determining the type of material constituting the object to be inspected, and a determination method using the calculation method. In addition, the purpose of another aspect is to accurately inspect an inspection object composed of a specific type of material even when a plurality of inspection objects include three or more types of inspection objects. A sorting method capable of sorting and a sorting apparatus are provided.

  According to an embodiment, there is provided a calculation method used for determining the type of material constituting the object to be inspected. The calculation method includes irradiating the inspection object with X-rays, detecting the transmission intensity of low energy X-rays transmitted through the inspection object, and the transmission intensity of high energy X-rays transmitted through the inspection object; For the object to be inspected, the method includes a step of calculating a relationship between a difference value obtained by weighting difference between the transmission intensity of low energy X-rays and the transmission intensity of high energy X-rays and a weighting coefficient used for the weighting difference.

  According to another embodiment, a determination method using the above calculation method is provided. The determination method weights the relationship corresponding to the object to be inspected and the transmission intensity of low energy X-rays and transmission intensity of high energy X-rays corresponding to each of a plurality of reference objects whose types of materials are known and different from each other. The method includes a step of determining the type of material constituting the object to be inspected based on the difference between the difference value and the weight coefficient used for the weighted difference.

  According to still another embodiment, a sorting method using the above calculation method is provided. The selection method includes a step of selecting the inspection object based on a difference value with respect to a predetermined weight coefficient value in the inspection object and a threshold value. The predetermined weight coefficient value weights the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known. It is set based on the difference between the difference value and the weighting factor used for the weighted difference. The threshold value includes a first difference value with respect to a predetermined weighting factor value in a designated reference object designated as a selection target among a plurality of reference objects, and a predetermined weighting factor value in the remaining reference objects. Is set based on the second difference value.

  In addition, the sorting apparatus according to another embodiment includes an irradiation unit that irradiates an inspection object with X-rays, transmission intensity of low-energy X-rays transmitted through the inspection object, and high-energy X-rays transmitted through the inspection object. The relationship between the detection unit for detecting the transmission intensity, the difference value obtained by weighting the transmission intensity of the low energy X-rays and the transmission intensity of the high energy X-rays, and the weighting coefficient used for the weighting difference for the inspection object. A relationship calculating unit for calculating.

  According to an aspect of the present disclosure, even when three or more types of inspection objects are included in a plurality of inspection objects, the types of materials constituting the inspection objects are accurately determined. And a determination method using the calculation method can be obtained.

  According to another aspect of the present disclosure, even when three or more types of inspection objects are included in a plurality of inspection objects, an inspection object composed of a specific type of material is accurately detected. You can sort well.

It is a flowchart which shows the determination method of the kind of material which comprises the to-be-inspected object according to Embodiment 1. 3 is a flowchart showing a database creation procedure according to the first embodiment. It is a figure which shows the relationship between the difference value and weighting coefficient according to Embodiment 1. 11 is a flowchart showing a database creation procedure according to the second embodiment. 10 is a flowchart showing a database creation procedure according to the third embodiment. It is a figure which shows the relationship between the difference value and weighting coefficient according to Embodiment 3. It is a figure which shows typically the selection apparatus according to Embodiment 4. FIG. It is a flowchart which shows an example of the selection process which the selection apparatus according to Embodiment 4 performs. It is a figure which shows typically the selection apparatus according to Embodiment 5. FIG. It is a figure for demonstrating an example of the setting method of the value of the weighting coefficient k. It is a figure for demonstrating the other example of the setting method of the value of the weighting coefficient k. It is a flowchart which shows an example of the selection process which the selection apparatus according to Embodiment 5 performs. It is a flowchart which shows the determination method of the kind of material which comprises the to-be-inspected object according to Embodiment 6. 20 is a flowchart showing a database creation procedure according to the sixth embodiment. It is a figure which shows the relationship between the difference value and weighting coefficient according to Embodiment 6. It is a figure which shows the relationship between the difference value and weighting coefficient according to Embodiment 6. It is a figure which shows typically the sorting apparatus according to Embodiment 7. FIG. It is a flowchart which shows an example of the selection process which the selection apparatus according to Embodiment 7 performs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
<Overview>
FIG. 1 is a flowchart showing a method for determining the type of material constituting an object to be inspected according to the first embodiment. As shown in FIG. 1, the method for determining the type of material constituting the inspection object according to the first embodiment (hereinafter simply referred to as “determination method”) is to irradiate the inspection object with X-rays and Step S100 (hereinafter also referred to as “detection step”) for detecting the transmission intensity of the low energy X-rays transmitted through and the transmission intensity of the high energy X-rays transmitted through the inspection object.

  The determination method is step S200 (hereinafter referred to as “below”) for the object to be inspected to obtain a relationship between a difference value obtained by weighting difference between the transmission intensity of low energy X-rays and the transmission intensity of high energy X-rays and the weighting difference. Also referred to as “calculation step”.

  The determination method is based on a plurality of relations corresponding to a plurality of different reference objects whose types of materials are known and the relations corresponding to the inspected objects. Step S300 for determining the type (hereinafter also referred to as “determination step”) is included.

  In the case of the food industry, the inspected object is, for example, sausage, a metal piece, a residual bone, etc., and in the case of the recycling industry, for example, gold, silver, aluminum, plastic (resin), etc. Not. Plastics include those containing glass fibers to increase strength, and those containing flame retardants to increase flame retardancy. Therefore, plastics can also be regarded as different types of substances (materials) depending on the difference in the additive contained.

Hereinafter, the determination method according to the first embodiment will be specifically described for each process.
<Details of each step of the judgment method>
(Detection process)
First, in the detection step (step S100), two types of X-rays (low energy X-rays and high energy X-rays) having different energy distributions are irradiated on the inspection object, and the respective X-ray intensities transmitted through the inspection object are measured. It is detected by one type of X-ray sensor. As the low energy X-ray and the high energy X-ray, respectively, an X-ray having a low energy distribution and an X-ray having a high energy distribution in a continuous X-ray spectrum are used. The detection of the transmission intensity of each X-ray is preferably executed at the same position and at the same time.

  Further, in the detection process, the X-ray sensor having two types of detection units that irradiate the inspection object with continuous X-rays and have different X-ray energy distributions that can be detected, and low-energy X-ray transmission intensity and high energy. X-ray transmission intensity may be detected. For example, this X-ray sensor has a structure in which two types of photodiodes with a scintillator (detection unit) are combined in two upper and lower stages. The upper detection unit detects low energy X-rays, and the lower detection unit detects high energy X-rays that have passed through the upper stage.

(Calculation process)
Next, calculation step (step S200), the transmitted intensity I _H of the transmitted intensity I _L and the high energy X-rays of the low energy X-ray obtained in the detection step, the irradiation intensity I _LO and high energy low-energy X-rays The irradiation intensity I _HO on the side is substituted into the following formula (1). J represents a difference value and k represents a weighting coefficient.

J = ln (I _L / I _LO ) −k · ln (I _H / I _HO ) (1)
Then, the weighting factor k is substituted into equation (1) as a variable, and a difference value J for each value of the weighting factor k is calculated. In other words, the relationship between the weighting factor k and the difference value J is a linear function with the weighting factor k and the difference value J as variables and ln (I _L / I _LO ) and ln (I _H / I _HO ) as constants. Can be represented.

(Judgment process)
Next, in the determination step (step S300), a database including information indicating the relationship between the difference value J and the weighting factor k for the reference object whose material type is known, and the object to be inspected are obtained in the calculation step. The type of material constituting the object to be inspected is determined by comparing the relationship.

  First, the contents of the database and the creation procedure will be specifically described. Information indicating the relationship between the difference value J and the weighting factor k included in the database is, for example, a linear line as shown in FIG. The database is created according to the procedure shown in FIG.

  The creation procedure until the database is stored in the memory will be described with reference to FIG. FIG. 2 is a flowchart showing a database creation procedure according to the first embodiment. As a preparation stage for creating the database, a plurality of reference objects divided for each type of material by fluorescent X-ray analysis or the like are prepared by paying attention to contained elements. Here, materials with similar chemical structures and materials with slightly different contents of additives and impurities are classified into the same type. It should be noted that the user can arbitrarily determine to what extent the difference in chemical structure and the content of additives and the like are regarded as the same type.

  Here, a case where three reference objects P1, reference objects P2, and reference objects P3 having different types of materials are prepared as a plurality of reference objects will be described. The reference object P1 is a plastic containing 10 wt% or more bromine as an additive. The reference object P2 is a plastic containing 5 wt% or more of chlorine as an additive. The reference object P3 is a plastic mainly containing carbon and hydrogen with a small amount of additive (eg, 1 wt% or less). The reference objects P1 to P3 are different from each other in content or type of additive.

  Referring to FIG. 2, the database creation method according to the first embodiment irradiates reference object P1 with X-rays, transmits low-energy X-rays transmitted through reference object P1, and increases the transmission intensity through reference object P1. Step S10 for detecting the transmission intensity of energy X-rays is included. In the database creation method, for the reference object P1, a relationship between the difference value J obtained by weighted difference between the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray and the weighting coefficient k used for the weighting difference is obtained in step S12. including. The database creation method includes step S14 of storing the relationship calculated in step S12 in a memory as a database.

  In addition, a series of processes of steps S10 to S14 are executed for the reference object P2 and the reference object P3. Thereby, a database including information indicating the relationship between the difference value and the weighting coefficient for each of the reference objects P1, P2, and P3 is created and stored in the memory. Specifically, when the types of the reference objects P1, P2, and P3 are the types T1, T2, and T3, straight lines 310 to 330 corresponding to the types T1 to T3 are created.

FIG. 3 shows a relationship between the difference value and the weighting factor according to the first embodiment. In FIG. 3, the vertical axis represents the difference value J, and the horizontal axis represents the weighting coefficient k. Here, the relationship between the difference value J and the weighting factor k for each reference object can be expressed by a straight line with ln (I _L / I _LO ) as the intercept of the vertical axis and ln (I _H / I _HO ) as the slope. it can. Specifically, the relationship for the reference object P1 is represented by a straight line 310 in FIG. 3, the relationship for the reference object P2 is represented by a straight line 320, and the relationship for the reference object P3 is represented by a straight line 330. The

  Thus, the relationship between the difference value J and the weighting factor k for the reference object is stored as information of a straight line. Specifically, as many straight lines as the number of types of materials are accumulated. Therefore, in the above description, an example in which three types of reference objects having different material types are prepared has been described. However, when four or more types of reference objects are prepared, four or more straight lines are obtained, and two types of reference objects are obtained. When preparing an object, two straight lines are obtained. In this way, it is possible to create a database in which the relationship between the difference value J and the weighting factor k for each material type is aggregated.

  Next, a method for determining the type of material constituting the inspection object using a database will be described. Specifically, in the determination step, a relationship that is most similar to a straight line corresponding to the object to be inspected is specified from among a plurality of relationships (straight lines) respectively corresponding to the plurality of reference objects. In the determination step, it is determined that the inspection object is the same type as the reference object corresponding to the specified relationship.

  In the example of FIG. 3, the straight line most similar to the straight line corresponding to the inspection object is specified from the straight lines 310 to 330 corresponding to the plurality of reference objects P1 to P3. As this specifying method, a method is conceivable in which the areas surrounded by the straight lines 310 to 330, the straight line corresponding to the object to be inspected, and two predetermined straight lines are compared and specified.

  For example, first, for the reference object P1, two lines indicated by a straight line 310, a straight line corresponding to the inspection object, and weighting factors k = x1 (for example, x1 = 1) and k = x2 (for example, x2 = 3). Calculate the area enclosed by the straight line. For the reference objects P2 and P3, the area is calculated by the same method. Then, it is specified that the straight line corresponding to the smallest area among the three calculated areas is most similar to the straight line corresponding to the inspection object. The two straight lines indicated by the weighting factor k described above may be two straight lines indicated by difference values J = y1 (for example, y1 = −0.8) and J = y2 (for example, y2 = 0.8).

  If all three calculated areas are larger than a predetermined reference area, none of the straight lines 310 to 330 may be similar to the straight line corresponding to the inspection object. . In this case, it is determined that the inspection object is of a type different from any of the reference objects P1 to P3. The reference area is arbitrarily set according to the determination accuracy desired by the user.

  Further, the above-described identification method is not limited to the above-described method, and is, for example, a method of comparing and specifying the inclination and intercept of each straight line corresponding to each reference object and the inclination and intercept of the straight line corresponding to the inspection object. There may be. For example, the difference (absolute value) between each inclination of the straight lines 310 to 330 and the inclination of the straight line corresponding to the inspection object is calculated, and the difference is scored. For example, a higher score is assigned to a straight line with a smaller difference (the higher the score, the higher the similarity). The same difference calculation is performed on the intercept, and a higher score is assigned to a straight line with a smaller difference. Of the straight lines 310 to 330, the straight line having the highest total value of the points given for the slope and the points given for the intercept is identified as being most similar to the straight line corresponding to the object to be inspected.

<Advantages>
According to the first embodiment, it is possible to determine to which type the inspection object belongs from among many types. Moreover, since it is sufficient to prepare as many types as the number of types for which a straight line indicating the relationship between the weighting coefficient and the difference value is to be determined, there is no limitation on the number of types that can be determined. For example, when the determination method is used for plastic recycling, the used plastic as the object to be inspected may contain many kinds of elements such as silicon, bromine, chlorine, calcium, titanium, and zinc. is there. Therefore, the determination method without limitation on the number of types that can be determined is more useful.

[Embodiment 2]
In the first embodiment, a configuration has been described in which a database is created by preparing one reference object for each type of material classified by focusing on the contained elements. In this case, since only one reference object needs to be prepared for each type, the database can be efficiently created. However, the primary straight line for a reference object classified as a certain type T and the linear line for a reference object classified as the same type T are slightly different due to variations in the thickness and chemical composition of the object. There is a case. For this reason, when this variation is large, it can be said that a determination method considering the variation is more preferable.

  In the second embodiment, a configuration in which a plurality of objects are prepared for each material type and a database is created will be described. The determination method according to the second embodiment is different from the determination method according to the first embodiment in the database used in the determination step described above. Since portions other than the database in the second embodiment are the same as those in the first embodiment, detailed description thereof will not be repeated.

  As a preparation stage for creating the database according to the second embodiment, a plurality of objects are prepared for each type. For example, for each of the reference objects P1, P2, and P3 described above, N (where N ≧ 2) objects that are the same type as the reference object are prepared.

  FIG. 4 is a flowchart showing a database creation procedure according to the second embodiment. Referring to FIG. 4, the database creation method according to the second embodiment irradiates N objects classified into type T1 with X-rays, and transmits low-energy X-ray transmission intensity for each of the N objects. And step S20 for detecting the transmission intensity of high-energy X-rays.

  The database creation method includes step S22 of calculating a difference value J obtained by weighted difference between the transmission intensity of low energy X-rays and the transmission intensity of high energy X-rays for each of N objects. Specifically, for each of the N objects, the difference coefficient J for each value of the weighting factor k is calculated by substituting the weighting factor k into the variable (1). Thereby, N difference values J are calculated for each value of the weight coefficient k. The database creation method also includes step S24 of calculating an average value of N difference values J for each value of the weighting factor k. That is, in step S24, the relationship between the average value of the N difference values J corresponding to the N objects classified into the type T1 and the weighting coefficient k is obtained. Then, the database creation method includes step S26 of storing the relationship obtained in step S24 in the memory as a database.

  In addition, a series of processes of steps S20 to S26 is performed on the N objects classified into the type T2 and the N objects classified into the type T3. Thereby, a database including information indicating the relationship between the average value of the N difference values J and the weighting coefficient k is created for each of the types T1, T2, and T3. In the above description, the configuration in which the same number (N) of objects is prepared for each type has been described. However, a different number (however, two or more) of objects may be prepared for each type.

  In the second embodiment, the relationship between the difference value J and the weighting factor k for each type can be expressed as a linear line with the vertical axis in FIG. 3 being the average value of the difference value J and the horizontal axis being the weighting factor k. . Typically, the primary straight lines corresponding to the types T1, T2, and T3 in the second embodiment are considered to be similar to the straight lines 310, 320, and 330 shown in FIG.

  In the determination step according to the second embodiment, the straight line most similar to the straight line corresponding to the inspection object is specified from among the plurality of primary straight lines, and the type of material constituting the inspection object is specified. It is determined that the type corresponds to the straight line.

<Advantages>
According to the second embodiment, the relationship between the average value of a plurality of difference values for a plurality of objects classified into the same type and the weighting coefficient is stored as a database. Therefore, even if there is an object for which a specific difference value is calculated among a plurality of objects classified into the same type, the difference values are averaged. Therefore, since the relationship between the specific difference value and the weighting coefficient for each type is not used as a database, the determination accuracy of the type of material constituting the object to be inspected can be improved.

[Embodiment 3]
In the second embodiment, the configuration in which the relationship between the average value of the plurality of difference values J corresponding to the plurality of objects prepared for each type and the weighting coefficient k is stored as a database has been described. In Embodiment 3, for each type, a configuration in which an upper limit curve and a lower limit curve based on the average value are stored as a database will be described.

  The determination method according to the third embodiment is different from the determination method according to the first embodiment in the determination process described above. About parts other than the determination process in Embodiment 3, since it is the same as the said part of Embodiment 1, the detailed description is not repeated.

  First, a database according to the third embodiment will be described. As a preparation stage for creating this database, a plurality of objects are prepared for each type of material as in the second embodiment. For example, for each of the reference objects P1, P2, and P3, N objects classified as the same type as the reference object are prepared.

  FIG. 5 is a flowchart showing a database creation procedure according to the third embodiment. Referring to FIG. 5, the database creation method according to the third embodiment irradiates N objects classified into the same type (for example, type T1) with X-rays. Step S40 for detecting the transmission intensity of energy X-rays and the transmission intensity of high-energy X-rays is included. The database creation method includes step S42 of calculating a difference value J for each value of the weighting coefficient k for each of the N reference objects.

  The database creation method includes step S44 of calculating an average value and a standard deviation of N difference values J for each value of the weight coefficient k. The database creation method includes a step S46 of calculating an upper limit value obtained by adding the standard deviation to the average value of the difference values J and a lower limit value obtained by subtracting the standard deviation from the average value for each value of the weighting factor k. . That is, in step S46, the relationship between the weighting factor k and the upper limit value and the relationship between the weighting factor k and the lower limit value are obtained. The database creation method includes step S48 in which the relationship obtained in step S46 is stored in the memory as a database.

  Also, the series of processes of steps S40 to S48 are executed for the N objects classified into the type T2 and the N objects classified into the type T3. Thus, a database including information indicating the relationship between the upper limit value and the weighting factor k and information indicating the relationship between the lower limit value and the weighting factor k is created for each of the material types T1, T2, and T3.

  FIG. 6 is a diagram showing the relationship between the difference value and the weighting factor according to the third embodiment. In FIG. 6, the vertical axis represents the difference value J, and the horizontal axis represents the weighting factor k. Referring to FIG. 6, the relationship between the upper limit value and weight coefficient k corresponding to types T1, T2, and T3 is represented by upper limit curves 510u, 520u, and 530u, respectively. The relationship between the lower limit value and the weight coefficient k corresponding to the types T1, T2, and T3 is represented by lower limit curves 510d, 520d, and 530d, respectively.

  A region 610 surrounded (configured) by the upper limit curve 510u and the lower limit curve 510d indicates a region of the difference value J that can be calculated for an object classified into the type T1 (a region in consideration of variation). Similarly, a region 620 surrounded by the upper limit curve 520u and the lower limit curve 520d indicates a region of the difference value J that can be calculated for an object classified as the type T2. A region 630 surrounded by the upper limit curve 530u and the lower limit curve 530d indicates a region of the difference value J that can be calculated for an object classified into the type T3. Referring to regions 610 to 630, it can be seen that the difference between the upper limit value and the lower limit value (that is, the standard deviation) differs depending on the value of the weighting factor k. This means that the influence of the variation in thickness and chemical composition of a plurality of objects classified as the same type on the difference value J varies depending on the value of the weight coefficient k.

  Next, a method for determining the type of material constituting the inspection object will be described using a database. Specifically, in the determination step according to the third embodiment, a plurality of regions 610 to 630 each composed of an upper limit curve and a lower limit curve respectively corresponding to a plurality of types T1 to T3, and a primary corresponding to the object to be inspected. By comparing with the straight line, the type of material constituting the object to be inspected is determined.

  Specifically, in the determination step, an area including a primary straight line corresponding to the inspection object is specified among the plurality of areas 610 to 630. More specifically, in the determination step, for each value of the weight coefficient k in a predetermined range (for example, 1 ≦ k ≦ 3) from among the plurality of regions 610 to 630, the object corresponds to the inspection object. A region where the difference value J satisfies the condition of lower limit value ≦ J ≦ upper limit value is specified. In the determination step, it is determined that the type of material constituting the object to be inspected is the same as the type corresponding to the specified area (for example, type T2 when the area 620 is specified). In addition, when none of the plurality of regions 610 to 630 satisfies the condition, it may be determined that the type of material constituting the inspection object is different from any of the types T1 to T3.

  In the above description, the configuration is described in which the value obtained by adding the average value and the standard deviation of the difference value J is defined as the upper limit value, and the value obtained by subtracting the standard deviation from the average value is defined as the lower limit value. The upper limit value and the lower limit value may be adjustable by adding or subtracting a value obtained by multiplying the average value by the standard deviation by z. The value of z can be arbitrarily set according to the determination accuracy desired by the user. For example, z is set smaller as the desired determination accuracy is higher.

<Advantages>
According to the third embodiment, the material constituting the object to be inspected using the relationship between the weight coefficient k and the difference value J in consideration of variations such as the thickness and chemical composition of a plurality of objects classified into the same type. Is determined. Therefore, the kind of material which comprises a to-be-inspected object can be determined appropriately.

[Embodiment 4]
In Embodiments 1 to 3, the method for determining the type of material constituting the object to be inspected has been described. In Embodiment 4, an object to be inspected apparatus and a method for selecting using the above determination method will be described. .

<Device configuration>
FIG. 7 is a diagram schematically showing a sorting apparatus according to the fourth embodiment. Referring to FIG. 7, sorting apparatus 100 includes a supply unit 2, a transport unit 3, an X-ray irradiation unit 4, an X-ray detection unit 5, a control unit 6, and a sorting unit 7.

  With reference to FIG. 7, the supply unit 2 supplies the inspection object 20 to the transport unit 3. The supply unit 2 includes, for example, a hopper and a feeder. The transport unit 3 transports the inspection object 20 supplied from the supply unit 2. The conveyance part 3 is comprised by the belt conveyor, the slider, the slide, etc., for example. The conveyance speed of the inspection object 20 in the conveyance unit 3 is, for example, 50 m / min to 100 m / min. The control unit 6 is configured to be able to determine whether the object to be inspected 20 is to be removed (removal target) or the object to be recovered (recovery target) even at the transport speed.

  The X-ray irradiation unit 4 irradiates the inspection object 20 conveyed by the conveyance unit 3 with X-rays. Typically, the X-ray irradiation unit 4 is installed at the upper part downstream of the transport unit 3. The inspection object 20 is irradiated with X-rays by the X-ray irradiation unit 4 after being emitted onto the transport unit 3 or from the transport unit 3 into the air.

  The X-ray detection unit 5 is installed below the X-ray irradiation unit 4 and detects X-rays transmitted through the inspection object 20 among the irradiated X-rays. The X-ray detection unit 5 transmits a detection signal to the control unit 6.

  The X-ray detection unit 5 is configured by, for example, a dual energy X-ray sensor. The dual energy X-ray sensor is a line sensor having the same width as that of the transport unit 3 and can detect a plurality of X-ray intensities on a straight line. For this reason, the inspection object 20 may be transported in a state where a plurality of the inspection objects 20 are arranged in a direction perpendicular to the transport direction on the transport unit 3. In this case, the X-ray detection unit 5 detects a plurality of X-ray intensities respectively transmitted through the plurality of inspection objects 20 and transmits them to the control unit 6.

  Note that the pixel size of the line sensor is desirably sufficiently smaller than the pixel size of the inspection object 20. For example, when plastic fragments with different additives are selected, the plastic fragment is about 4 mm at least, so the X-ray sensor may use a pixel having a size of 0.4 mm × 0.4 mm. In this case, transmission intensity data in the alignment direction of the pixels in the acquired sensor and in the time axis direction are obtained for one inspection object 20. As described above, a plurality of transmission intensity data of the object to be inspected 20 are acquired, and it is appropriate to use a value having a low transmission intensity as the transmission intensity data. For example, the minimum value of a plurality of transmission intensity data obtained for one inspection object 20 may be used, or some of the transmission intensity data within a certain range based on the minimum value are averaged. The value may be used as transmission intensity data.

  The control unit 6 determines the type of the inspection object 20 based on the detection signal received from the X-ray detection unit 5. The control unit 6 determines whether the inspection object 20 is an object to be collected or an object to be removed based on the determined type. The control unit 6 transmits information necessary for selecting the inspection object 20 to the selection unit 7 based on the determination result. The sorting unit 7 sorts the inspection object 20 based on information from the control unit 6.

  Here, the configuration of the control unit 6 will be described in detail. The control unit 6 is realized by a processor such as a CPU (Central Processing Unit), a program executed by the processor, a memory for storing various data, and hardware such as an input / output interface. The control unit 6 includes an input unit 61, a relationship calculation unit 62, a determination unit 64, and an information output unit 65 as main functional configurations. These configurations are realized mainly by a processor executing a program stored in a memory. Note that some or all of these functional configurations may be realized by hardware. The control unit 6 further includes a storage unit 63 realized by a memory.

  The input unit 61 receives an input of a detection result (detection signal) from the X-ray detection unit 5. Specifically, the input unit 61 receives, as detection signals, inputs of low-energy X-ray transmission intensity and high-energy X-ray transmission intensity of the inspection object 20. Note that the input unit 61 may be configured to perform a smoothing process for noise reduction when receiving an input of a detection signal.

The relationship calculation unit 62 obtains a relationship between a difference value obtained by weighting the low-intensity X-ray transmission intensity and the high-energy X-ray transmission intensity with respect to the inspection object 20 and a weighting coefficient used for the weighting difference. Specifically, the relationship calculation unit 62 obtains a straight line indicating the relationship between the weighting factor k and the difference value J for the object to be inspected using the above equation (1). The low-energy X-ray irradiation intensity I _LO and the high-energy X-ray irradiation intensity I _HO used in Expression (1) are stored in advance in a memory (for example, the storage unit 63).

  The storage unit 63 stores a database in which the relationship between the difference value J and the weight coefficient k for each type of reference object is aggregated. Specifically, the storage unit 63 stores at least one of the three databases used in the first to third embodiments.

  The determination unit 64 determines the type of the inspection object 20 based on the database stored in the storage unit 63 and the relationship between the weighting coefficient k and the difference value J for the inspection object 20. Specifically, the determination unit 64 performs the determination using the method described in the determination process in the first to third embodiments.

  In addition, the determination unit 64 determines whether the inspection object 20 is an object to be removed (removal object) or an object to be recovered based on the determination result of the type of the inspection object 20 and a preset selection criterion. Determine whether it is a (collection object). The sorting standard is a standard for removing (or collecting) a certain type of object. Here, as a selection criterion, for example, consider a case where a criterion is set that an object of type T2 is removed and another type of object is collected. In this case, when the determination unit 64 determines that the type of the inspection object 20 is the type T2, the determination unit 64 further determines that the inspection object 20 is a removal object. On the other hand, if the determination unit 64 determines that the type of the inspection object 20 is other than the type T2 (for example, the type T1), the determination unit 64 further determines that the inspection object 20 is a collection object.

  The information output unit 65 outputs information for removing (or collecting) the inspection object 20 to the selection unit 7 based on the determination result of the determination unit 64. Specifically, the information output unit 65 outputs an operation signal to the selection unit 7 when the inspection object 20 is a removal target. On the other hand, the information output unit 65 does not output an operation signal to the selection unit 7 when the inspection object 20 is a collection target.

  Next, the configuration of the selection unit 7 will be described more specifically. The sorting unit 7 includes an air gun 71, a removal box 72, and a collection box 73. When the air gun 71 receives an operation signal from the information output unit 65 (when the inspection object 20 is a removal object), the air gun 71 injects air onto the inspection object 20. For example, the air gun 71 is connected to an air cylinder (not shown) and injects air sent from the air cylinder. In this case, the inspection object 20 falls into the removal box 72 in which the removal target object is accommodated. On the other hand, when the air gun 71 does not receive an operation signal (when the inspection object 20 is a recovery object), air is not injected to the inspection object 20. Therefore, the inspected object 20 falls into the collection box 73 in which the collection target object is accommodated.

  The sorting method is an effective method when it is estimated that the collection target objects are included in the plurality of inspected objects 20 more than the removal target objects. On the other hand, when it is estimated that the removal target object is included in a larger amount than the recovery target object, a configuration in which air is injected to the recovery target object may be employed. Specifically, the information output unit 65 outputs an operation signal to the sorting unit 7 when the inspection object 20 is a collection object, and selects the operation signal when the inspection object 20 is a collection object. Do not output to 7. In this case, when air is sprayed onto the inspection object 20, the inspection object 20 is configured to fall into the collection box 73. On the other hand, when air is not jetted to the inspection object 20, the inspection object 20 is configured to drop into the removal box 72.

  In the above sorting method, the information output unit 65 is configured to output a signal only when the inspection object 20 is a removal target (or a recovery target), but is limited to this configuration. Absent. The information output unit 65 may output a signal regardless of whether the inspection object 20 is a removal target or a recovery target. For example, assume that the air gun 71 includes two air guns for removal and collection. In this case, when the inspection object 20 is a removal target, the information output unit 65 outputs an operation signal to the air gun for removal. When the inspection object 20 is a collection object, the information output unit 65 outputs an operation signal to the collection air gun.

  Further, there may be a case where one air gun 71 can drop the inspection object 20 into both the removal box 72 and the collection box 73 by changing the air injection direction. When the inspection object 20 is a removal object, the information output unit 65 outputs an operation signal for dropping the inspection object 20 to the removal box 72 to the air gun 71. When the inspection object 20 is a collection object, the information output unit 65 outputs an operation signal for dropping the inspection object 20 to the collection box 73 to the air gun 71.

<Processing procedure>
FIG. 8 is a flowchart showing an example of the sorting process executed by the sorting apparatus 100 according to the fourth embodiment. Referring to FIG. 8, the X-ray irradiation unit 4 irradiates the inspection object 20 with X-rays (step S402). X-ray detection unit 5, transmitted through the object to be inspected 20, for detecting the transmitted intensity _{I H} of the transmitted intensity _{I L} and the high energy X-ray of the low energy X-ray (Step S404).

Control unit 6 uses the transmitted intensity I _L and the transmitted intensity I _H obtained from the X-ray detector 5, the object to be inspected 20, obtains the relationship between the weighting factor k and the difference value J (step S406). The control unit 6 compares the database stored in the memory in advance with the relationship regarding the inspection object 20, and determines the type of the inspection object 20 (step S408). The control unit 6 determines whether or not the inspection object 20 is a removal object based on the type determination result and a predetermined selection criterion (step S410).

  If the inspection object 20 is a removal object (YES in step S410), the sorting unit 7 removes the inspection object 20 (step S412). Specifically, the sorting unit 7 stores the inspection object 20 in the removal box 72 in accordance with an instruction from the control unit 6. Then, the process ends. On the other hand, when the inspection object 20 is a collection object (NO in step S410), the sorting unit 7 collects the inspection object 20 (step S414). Specifically, the sorting unit 7 stores the inspection object 20 in the collection box 73 in accordance with an instruction from the control unit 6. Then, the process ends.

<Advantages>
According to the fourth embodiment, the inspection object 20 can be selected using the determination method according to the first to third embodiments.

[Embodiment 5]
In the fifth embodiment, a sorting method different from the sorting method of the inspection object according to the fourth embodiment will be described. The sorting apparatus according to the fifth embodiment sets an appropriate value of the weighting factor k using the above-described database. The sorting device sorts the object to be inspected by comparing the difference value J with respect to the set weight coefficient k and a predetermined threshold value.

<Device configuration>
FIG. 9 schematically shows sorting apparatus 100A according to the fifth embodiment. The sorting apparatus 100A has a configuration in which the control unit 6 of the sorting apparatus 100 is replaced with a control unit 6A. Therefore, since the configuration of the sorting apparatus 100A other than the control unit 6A is the same as that of the sorting apparatus 100, detailed description thereof will not be repeated.

  The control unit 6A includes an input unit 61A, a relationship calculation unit 62A, a determination unit 64A, an information output unit 65A, a coefficient setting unit 66A, and a threshold setting unit 67A as main functional configurations. These configurations are realized mainly by a processor executing a program stored in a memory. Note that some or all of these functional configurations may be realized by hardware. Control unit 6A further includes a storage unit 63A. The input unit 61A, the relationship calculation unit 62A, and the storage unit 63A are substantially the same as the input unit 61, the relationship calculation unit 62, and the storage unit 63 in FIG.

  The coefficient setting unit 66A sets the value of the weight coefficient k for selecting the inspection object 20 based on the database (a plurality of primary straight lines corresponding to a plurality of types) stored in the storage unit 63A. . A method for setting the value of the weighting coefficient k of the coefficient setting unit 66A will be described.

  First, a method for setting the value of weighting factor k based on the database according to the first embodiment will be described with reference to FIG. The method for setting the value of weighting factor k based on the database according to the second embodiment is the same as the method described below.

  FIG. 10 is a diagram for explaining an example of a method for setting the value of the weight coefficient k. The straight lines 310 to 330 in FIG. 10 are the same as those in FIG. Here, a case is considered in which a criterion for removing (or collecting) a type T2 object and collecting (or removing) another type of object is set as a selection criterion. That is, the reference object P2 of the type T2 among the plurality of reference objects P1 to P3 is designated as the object to be selected.

  Referring to FIG. 10, first, the coefficient setting unit 66A has a difference value J2 corresponding to the reference object P2 designated as the selection target based on the plurality of straight lines 310 to 330 of the remaining reference objects P1 and P3. The range of the weighting coefficient k that is larger (or smaller) than any of the difference values J1 and J3 corresponding to each is specified. In the example of FIG. 10, α1 (= 1) <k <α2 (, where the difference value J2 on the straight line 320 is smaller than any of the difference values J1 and J3 on the straight lines 310 and 330. = 2.8) is specified. In the example of FIG. 10, there is no range of the weighting coefficient k in which the difference value J2 is larger than any of the difference values J1 and J3.

  Then, the coefficient setting unit 66A sets a value at which the difference between the difference value J2 and the difference values J1 and J3 among the values of the weighting coefficient k satisfying α1 <k <α2 is relatively large. Is set as the value of the weighting coefficient k for selecting. For example, the coefficient setting unit 66A determines that the difference between the difference value J2 and the difference value J1 (| J1-J2 |) is the same as the difference between the difference value J2 and the difference value J3 (| J3-J2 |) (1 .75) is set as the value of the weighting factor k. Alternatively, the coefficient setting unit 66A determines that both | J1-J2 | and | J3-J2 | of the values of the weighting coefficient k satisfying α1 <k <α2 are predetermined values (for example, 0.1 A value satisfying the condition of greater than () may be set as the value of the weight coefficient k.

  Referring to FIG. 9 again, threshold setting unit 67A determines difference value J2 for reference object P2 with respect to the value of weighting coefficient k set by coefficient setting unit 66A and the corresponding weights for remaining reference objects P1 and P3. A threshold Th is set based on the difference values J1 and J3 with respect to the value of the coefficient k. Specifically, the threshold setting unit 67A sets the threshold Th between the difference value J2 and the difference value J1, and between the difference value J2 and the difference value J3.

  Referring to FIG. 10, a case is considered where the value of weighting factor k is set to 1.75 by coefficient setting unit 66A. When k = 1.75, J2≈−0.4, and J1, J3≈−0.18. Therefore, the threshold value Th is set in a range of −0.40 <Th <−0.18. Here, it is assumed that the reference object P2 is a removal target and the reference objects P1 and P3 are collection targets. When it is desired to increase the removal rate of the inspection object 20 (that is, when it is easy to determine the inspection object 20 as a removal object), the threshold Th is set near the difference values J1 and J3 (≈−0.18). Is done. When it is desired to reduce the removal rate of the inspection object 20 (that is, when it is difficult to determine the inspection object 20 as an object to be removed), the threshold value Th is set near the difference value J2 (≈−0.40). .

  Based on the difference value J with respect to the value of the weighting coefficient k set by the coefficient setting unit 66A and the threshold value Th, the determination unit 64A determines whether the inspection target 20 is a removal target or a collection target. Determine if it is a thing. According to the above example, the determination unit 64A determines that the inspection object 20 is a collection target (that is, a type different from the reference object P2) when the difference value J is equal to or greater than the threshold Th, and When the difference value J is less than the threshold Th, it is determined that the inspection object 20 is a removal target (that is, the same type as the reference object P2).

  In addition, when the reference object P2 is a collection target and the reference objects P1 and P3 are removal objects, the determination result by the determination unit 64A is opposite to the above. Specifically, the determination unit 64A determines that the inspection object 20 is a removal target when the difference value J is greater than or equal to the threshold Th, and when the difference value J is less than the threshold Th. It determines with the to-be-inspected object 20 being a collection | recovery object.

  The information output unit 65A typically has a function similar to the function of the information output unit 65 described above. The information output unit 65A may be configured to output the determination result (determination result whether or not the difference value J is less than the threshold Th) by the determination unit 64A. In this case, the sorting unit 7 may be configured to remove (or collect) the inspection object 20 based on the determination result. For example, when the determination unit 7 receives the determination result that the difference value J is less than the threshold value Th, the sorting unit 7 removes the inspection object 20 and receives the determination result that the difference value J is equal to or more than the threshold value Th. In some cases, the inspection object 20 is configured to be collected.

  Next, referring to FIG. 11, a method for setting the value of weighting factor k based on the database according to the third embodiment will be described. FIG. 11 is a diagram for explaining another example of a method of setting the value of the weighting factor k. Each upper limit curve 510u, 520u, 530u, each lower limit curve 510d, 520d, 530d, and each area | region 610-630 in FIG. 11 are the same as those in FIG. Here, it is assumed that the reference object P2 of the type T2 among the plurality of reference objects P1 to P3 is designated as the object to be selected.

  Referring to FIG. 11, first, coefficient setting unit 66A has a remaining area 620 corresponding to designated reference object P2 among a plurality of areas 610 to 630 respectively corresponding to a plurality of reference objects P1 to P3. The range of the weight coefficient k that does not overlap with any of the areas 610 and 630 corresponding to the reference objects P1 and P3 is specified. In the example of FIG. 11, β1 (= 1.75) <k <β2 (= 2.25) is specified as the range of the weighting factor k in which the region 620 does not overlap with any of the regions 610 and 630. If there is no value of the weighting factor k that does not overlap, the upper limit value and the lower limit value may be adjusted using the above-described method so that the value exists.

  The coefficient setting unit 66A determines that the difference between the difference value J2 in the area 620 and the difference value J1 in the area 610 and the difference value J3 in the area 630 among the values of the weighting coefficient k satisfying β1 <k <β2. A relatively large value is set as the value of the weight coefficient k for selecting the inspection object 20. In the example of FIG. 11, in the range of β1 <k <β2, the upper limit value of the difference value J2 is smaller than the lower limit values of the difference values J1 and J3. For this reason, the coefficient setting unit 66A, for example, has a value (1) where the difference between the upper limit value of the difference value J2 and the lower limit value of the difference value J1 is the same as the difference between the upper limit value of the difference value J2 and the lower limit value of the difference value J3. .9) is set as the value of the weighting factor k. Alternatively, the coefficient setting unit 66A may set a value that satisfies the condition that these differences are greater than a predetermined value (for example, 0.1) as the value of the weight coefficient k.

  Referring to FIG. 9 again, threshold setting unit 67A sets threshold Th between difference value J2 and difference value J1, and between difference value J2 and difference value J3. According to the example of FIG. 11, the threshold value setting unit 67A is between the upper limit value of the difference value J2 and the lower limit value of the difference value J1, and between the upper limit value of the difference value J2 and the lower limit value of the difference value J3. The threshold value Th is set. Note that the determination method by determination unit 64A is similar to the method described above, and thus detailed description thereof will not be repeated.

<Processing procedure>
FIG. 12 is a flowchart showing an example of the sorting process executed by the sorting apparatus 100A according to the fifth embodiment. Here, it is assumed that the relationship between the weighting coefficient k and the difference value J in the plurality of reference objects P1 to P3 is as shown in FIG. 10 (or FIG. 11). In addition, the inspection object 20 of the same type as the type T2 of the reference object P2 is removed, and the inspection object 20 of the same type as the other types T1, T3 is collected. The type of the inspection object 20 is assumed to be any of the types T1 to T3. In addition, it is assumed that the value of the weighting coefficient k and the value of the threshold value Th for selecting the inspection object 20 are set in advance by the method described above.

  Referring to FIG. 12, the processes of steps S502, S504, and S506 are the same as the processes of steps S402, S404, and S406, respectively, and thus detailed description thereof will not be repeated. The control unit 6A calculates a difference value J with respect to a value (for example, 1.75) of a weighting factor k set in advance for selecting the inspection object 20 by using the relationship obtained in step S506 (step S506). S508). The controller 6A determines whether or not the calculated difference value J is less than the threshold value Th (step S510).

  When the difference value J is less than the threshold Th (that is, the inspection object 20 is the same type as the reference object P2) (YES in step S510), the selection unit 7 removes the inspection object 20 (step S512). ). Then, the process ends. On the other hand, when the difference value J is greater than or equal to the threshold Th (NO in step S510), the sorting unit 7 collects the inspection object 20 (step S514). Then, the process ends.

<Advantages>
According to the fifth embodiment, since the value of the weighting factor and the threshold value for selecting the inspection object are set, the inspection object can be easily and efficiently selected.

  In addition, for example, in plastic recycling, even when a plurality of types of plastics are mixed, it is possible to accurately select a plastic to be collected and other plastics. Therefore, even when a chlorinated plastic having a high chlorine concentration is mixed in a plurality of plastics, the chlorinated plastic can be removed. Therefore, utilization as a thermal recycling material is promoted.

[Embodiment 6]
In the first embodiment, by using one database, among the plurality of relationships (straight lines) respectively corresponding to a plurality of reference objects, the relationship that is most similar to the straight line corresponding to the object to be inspected is specified. The structure for determining the type of material constituting the material has been described. Thus, when using the similarity of a straight line as a criterion, for example, when there are a plurality of straight lines that are very similar to the straight line corresponding to the object to be inspected, it is possible to erroneously determine the material constituting the object to be inspected. There is sex.

  Therefore, in the sixth embodiment, two databases are created for each reference object. If there are multiple straight lines in the first database that are highly similar to the straight line corresponding to the inspection object, the second database is used to resemble the straight line corresponding to the inspection object. By selecting a highly straight line, the type of material constituting the inspection object is determined.

Hereinafter, the determination method according to the sixth embodiment will be specifically described for each process.
<Details of each step of the judgment method>
(Detection process)
In the first embodiment, the configuration in which the inspection object is irradiated with two types of X-rays (low energy X-ray and high energy X-ray) having different energy distributions has been described. In the sixth embodiment, four types of energy distributions having different energy distributions are described. A configuration for irradiating an object to be inspected with X-rays will be described.

  FIG. 13 is a flowchart showing a method for determining the type of material constituting the inspection object according to the sixth embodiment.

  Referring to FIG. 13, in the detection step (step S <b> 101), four types of X-rays having different energy distributions are irradiated on the inspection object, and the respective X-ray intensities transmitted through the inspection object are detected. Specifically, the inspection object is irradiated with continuous X-rays using an X-ray source. For example, as the X-ray source, an X-ray tube using tungsten as a target is used, and the tube voltage is set to 50 kV. Subsequently, the transmission intensity of X-rays having energy E1 (hereinafter referred to as “E1 energy X-rays”) using an X-ray sensor having two types of detection units with different X-ray energy distributions that can be detected; The transmission intensity of X-rays having energy E2 higher than energy E1 (hereinafter referred to as “E2 energy X-rays”) is detected.

  Next, an X-ray source having a different target from the X-ray source is used to irradiate the inspection object with continuous X-rays having an energy distribution different from that of the continuous X-rays. The target of the X-ray source may be rhodium, molybdenum, chromium, or the like that can generate not only continuous X-rays but also characteristic X-rays at a tube voltage of 50 kV or less. The target can be used in consideration of the absorption band of the measurement object. Subsequently, using the X-ray sensor, the transmission intensity of X-rays having energy E3 different from the energy E1, E2 (hereinafter referred to as “E3 energy X-ray”) is different from the energy E1, E2, The transmission intensity of X-rays having energy E4 higher than energy E3 (hereinafter referred to as “E4 energy X-rays”) is detected.

(Calculation process)
Next, in the calculation step (step S201), two types of relationships between the difference value and the weighting coefficient are obtained for the inspection object. Specifically, two of the four types of X-ray transmission intensities obtained in the detection step are combined and substituted into equation (1). Here, the transmission intensities of E1, E2, E3, and E4 energy X-rays are I _E1 , I _E2 , I _E3 , and I _E4 , respectively, and the irradiation intensities of E1, E2, E3, and E4 energy X-rays are I _E1O and I _E , respectively. _{Let E2O} , _IE3O , and _IE4O .

For example, a combination of transmission intensity I _E1 and transmission intensity I _{E2 and} a combination of transmission intensity I _E3 and transmission intensity I _E4 are used. When the combination of the transmission intensity I _E1 and the transmission intensity I _E2 is applied to the equation (1), the relationship between the weighting coefficient k and the difference value J is ln (I _E1 / I _E1O ) and ln (I _E2 / I _E2O ) can be expressed as linear functions. When the combination of the transmission intensity I _E3 and the transmission intensity I _E4 is applied to the equation (1), the relationship between the weight coefficient k and the difference value J is ln ( I _E3 / I _E3O ) and ln (I _E4 / I _E4O ) can be expressed as linear functions.

In this way, as a first type of relationship with respect to the object to be inspected, a relationship between a difference value obtained by weighting difference between the transmission intensity I _E1 and the transmission intensity I _E2 and the weight coefficient is obtained. Further, as a second type of relationship for the object to be inspected, there is obtained a relationship between a difference value obtained by weighted difference between the transmission intensity I _E3 and the transmission intensity I _E4 and a weight coefficient.

(Judgment process)
Next, in the determination step (step S301), a database including information indicating the relationship between the difference value J and the weighting factor k for the reference object whose material type is known, and the object to be inspected are obtained in the calculation step. The type of material constituting the object to be inspected is determined by comparing the relationship.

  First, the contents and creation procedure of the database according to the sixth embodiment will be specifically described. Information indicating the relationship between the difference value J and the weight coefficient k included in the database is, for example, a linear line as shown in FIGS. 16 and 17 described later. The database is created in the procedure as shown in FIG.

  With reference to FIG. 14, the creation procedure until the database is stored in the memory will be described. FIG. 14 is a flowchart showing a database creation procedure according to the sixth embodiment. For example, the plurality of reference objects P1, P2, and P3 described above are prepared as a preparation stage for creating a database.

  Referring to FIG. 14, the database creation method according to the sixth embodiment includes step S81 of irradiating reference object P1 with X-rays to detect transmission intensities of four types of X-rays having different energy distributions. Specifically, the transmission intensity of the E1 energy X-ray transmitted through the reference object P1 and the transmission intensity of the E2 energy X-ray transmitted through the reference object P1 are detected. Subsequently, the transmission intensity of the E3 energy X-ray transmitted through the reference object P1 and the transmission intensity of the E4 energy X-ray transmitted through the reference object P1 are detected.

  The database creation method includes a step 82 for obtaining two types of relationships between the difference value J and the weighting coefficient k for the reference object P1. Specifically, as a first type of relationship with respect to the reference object P1, a relationship between a difference value J obtained by weighted difference between the transmission intensity of E1 energy X-rays and the transmission intensity of E2 energy X-rays and a weighting coefficient k is calculated. . Further, as a second type of relationship with respect to the reference object P1, a relationship between a difference value obtained by weighting difference between the transmission intensity of E3 energy X-rays and the transmission intensity of E4 energy X-rays and a weighting coefficient is calculated.

  The database creation method includes step S83 of storing the plurality of relationships calculated in step S82 as a database in a memory.

  In addition, the series of processing of steps S81 to S83 is also performed for the reference object P2 and the reference object P3. Thereby, for each of the reference objects P1, P2, and P3, a database including information indicating two types of relationship between the difference value and the weighting coefficient is created and stored in the memory. Specifically, two straight lines (linear function) corresponding to the type T1 of the reference object P1 are created, two straight lines corresponding to the type T2 of the reference object P2 are created, and the type corresponds to the type T3 of the reference object P3. Two straight lines are created.

  15 and 16 are diagrams showing the relationship between the difference value and the weighting factor according to the sixth embodiment. Specifically, FIG. 15 is a diagram illustrating the first type of relationship between the difference value and the weighting factor, and FIG. 16 is a diagram illustrating the second type of relationship between the difference value and the weighting factor.

  Referring to FIG. 15, the first type of relationship for reference object P1 is represented by straight line 310A in FIG. 15, and the first type of relationship for reference object P2 is represented by straight line 320A. The first type of relationship is represented by a straight line 330A. The first type of relationship for the object to be inspected is represented by a straight line 500A in FIG.

  Similarly, referring to FIG. 16, the second type of relationship for reference object P1 is represented by straight line 310B in FIG. 16, and the second type of relationship for reference object P2 is represented by straight line 320B. The second type of relationship for P3 is represented by a straight line 330B. Note that the second type of relationship for the object to be inspected is represented by a straight line 500B in FIG.

  Thus, the relationship between the difference value J and the weighting factor k for the reference object is stored as information of a straight line. Therefore, for each material type, a database D1 (for example, straight lines 310A, 320A, 330A in FIG. 15) that summarizes the first type relationship between the difference value J and the weighting factor k, the difference value J, and the weighting factor k. A database D2 (for example, straight lines 310B, 320B, and 330B in FIG. 16) that collects the second type of relationship is obtained.

  Next, a method for determining the type of material constituting the inspection object using a database will be described. First, a straight line most similar to a straight line corresponding to an object to be inspected is specified from among a plurality of relationships (straight lines) respectively corresponding to a plurality of reference objects using the first type of database D1. Here, referring to FIG. 15, a straight line 500A corresponding to the inspection object is very similar to both a straight line 310A corresponding to the reference object P1 and 320A corresponding to the reference object P2. In this case, if the type of material constituting the object to be inspected is determined by specifying the straight line most similar to the straight line 500A using the area comparison as described in the first embodiment, there is a possibility of erroneous determination. . Therefore, when the straight line corresponding to the inspection object (for example, the straight line 500A) is highly similar to a plurality of straight lines (for example, the straight lines 310A and 320A), the second type of database D2 is used.

  Whether the similarity is high is determined using the area comparison described in the first embodiment. For example, an area S1 surrounded by a straight line 310A, a straight line 500A corresponding to the object to be inspected, and two straight lines indicated by weighting factors k = x1 and k = x2 is calculated. For the reference objects P2 and P3, the areas S2 and S3 are calculated by the same method. Then, two different areas are selected from the calculated three areas S1 to S3, and a difference between the two selected areas is calculated. Specifically, the differences | S1-S2 |, | S1-S3 |, | S2-S3 | are calculated. If the difference is smaller than a predetermined value, the straight line 500A corresponding to the inspection object is determined to include a plurality of straight lines having high similarity. For example, when the difference | S1-S2 | is smaller than a predetermined value, it is determined that the straight line 500A is highly similar to the plurality of straight lines 310A and 320B.

  And when it is judged that the straight line corresponding to a to-be-inspected object has high similarity with a some straight line, using the 2nd type database D2, among a plurality of straight lines respectively corresponding to a plurality of reference objects, A straight line most similar to the straight line corresponding to the object to be inspected is specified. Referring to FIG. 16, since the straight line 500B corresponding to the inspection object is clearly more similar to the straight line 310B than the straight line 320B, the type of material constituting the inspection object is the type T1 of the reference object P1. It can be determined that there is.

<Advantages>
According to the sixth embodiment, when there are a plurality of straight lines having high similarity to the straight line corresponding to the inspected object using the first type of database, the second type of database is used to inspect the inspected object. By selecting a straight line having high similarity to the corresponding straight line, the type of material constituting the inspection object is determined. Thereby, the determination accuracy of the type of material of the object to be inspected can be further improved.

[Embodiment 7]
In the seventh embodiment, a configuration will be described in which the threshold value used in the sorting method according to the fifth embodiment is changed based on the above-described database.

<Device configuration>
FIG. 17 is a diagram schematically showing sorting apparatus 100B according to the seventh embodiment. The sorting apparatus 100B has a configuration in which the control unit 6A of the sorting apparatus 100A is replaced with a control unit 6B. Therefore, since the configuration of the sorting device 100B other than the control unit 6B is the same as that of the sorting device 100A, detailed description thereof will not be repeated.

  Referring to FIG. 17, control unit 6B has an input unit 61B, a relationship calculation unit 62B, a determination unit 64B, an information output unit 65B, a coefficient setting unit 66B, and a threshold setting unit 67B as main functional configurations. A type determination unit 68B and a totaling unit 69B are included. These configurations are realized mainly by a processor executing a program stored in a memory. Note that some or all of these functional configurations may be realized by hardware. Control unit 6B further includes a storage unit 63B. The input unit 61B, the relationship calculation unit 62B, the determination unit 64B, the information output unit 65B, and the coefficient setting unit 66B are respectively the input unit 61A, the relationship calculation unit 62A, the determination unit 64A, the information output unit 65A, and the like in FIG. And it is substantially the same as the coefficient setting unit 66A.

  The type determination unit 68B determines the type of material constituting the object to be inspected using the determination method described in the first to third and sixth embodiments.

  Similar to storage unit 63A according to the fifth embodiment, storage unit 63B stores a database in which the relationship between difference value J and weight coefficient k for each type of reference object is aggregated. In addition, the storage unit 63B includes information (for example, a determination result of the determination unit 64B) indicating whether the inspection object 20 is a removal target or a recovery target, and a determination result of the type determination unit 68B (that is, the inspection target). The determination result of the type of material constituting the object 20) is stored. The information indicating whether the inspection object 20 is a removal object or a recovery object indicates whether the inspection object 20 is sorted as a removal object or a collection object by the sorting unit 7. It may be the sorting result shown. Furthermore, the storage unit 63B stores the difference value (that is, the difference value J with respect to the value of the weighting coefficient k set by the coefficient setting unit 66B) in the inspection object 20 used for the determination by the determination unit 64B.

  As described above, the storage unit 63B stores the inspected object 20 in association with the determination result of the type of material, information indicating whether the object is a removal object or a recovery object, and the difference value.

  The totaling unit 69B totals data related to the inspection object 20 stored in the storage unit 63B. Specifically, the counting unit 69B determines that the number of the inspected objects 20 and the types T1, T2, and T3 are the number of the inspected objects 20 that are determined to be the type and the objects to be removed. The number of inspected objects 20 and the number of inspected objects 20 determined to be collection objects are counted.

  The threshold value setting unit 67B corrects the threshold value Th used by the determination unit 64B based on the total data (for example, the total data regarding 1000 or more inspected objects 20) related to the inspection object 20 of the specified number or more (that is, the re-establishment). Set). Specifically, the threshold setting unit 67B sets the threshold Th based on the determination result of the type determination unit 68B and the determination result (or the selection result) of the determination unit 64B in each of the inspection objects 20 of the specified number or more. Correct it.

  More specifically, the threshold setting unit 67B corrects the threshold Th using the erroneous determination rate of the determination unit 64B. Here, let us consider a case where objects of types T1, T2, and T3 are to be inspected, and an object of type T2 is an object to be removed. In this case, for example, the misjudgment rate of the type T2 is (the number of the inspected objects 20 in which the determination unit 64B erroneously determines that the removal target is a collection target) / (the type determination unit 68B is a removal target. The number of inspected objects 20 determined).

  “The determination unit 64B erroneously determines that the removal target is a collection target” means that the type of the inspection object 20 is the type T2 (that is, the inspection object 20 is the removal object). This means that the object to be inspected 20 has been determined as a collection object by the determination unit 64B, although it has been determined by the determination unit 68B.

  Here, it is assumed that the setting criterion is a criterion for setting the threshold Th so that the misjudgment rate of the type T2 is 1% or less. In this case, the threshold setting unit 67B corrects the threshold Th so that the erroneous determination rate is 1% or less when the erroneous determination rate of the type T2 is larger than 1%.

  In one aspect, the threshold setting unit 67B refers to the counting results of the storage unit 63B and the counting unit 69B, and selects the value of the weight coefficient k (from the inspected object 20 determined by the type determining unit 68B as the type T2) ( For example, the number of inspected objects 20 for which the difference value J with respect to 1.75) is equal to or greater than the threshold Th is counted. Then, the threshold setting unit 67B corrects the threshold Th so that a value obtained by dividing the counted number by the number of the inspected objects 20 determined as the type T2 by the type determining unit 68B is 1% or less. Note that the threshold setting unit 67B may correct the threshold Th so that the erroneous determination rate becomes 0%.

  In another aspect, the threshold setting unit 67B corrects the threshold Th based on the type distribution of the inspection object 20 accommodated in the removal box 72 or the type distribution of the inspection object 20 terminated in the collection box 73. . For example, it is assumed that the inspection object 20 of type T2 is a removal target and the inspection objects 20 of types T1 and T3 are recovery objects. In this case, the threshold value setting unit 67B is determined as a collection target by the determination unit 64B, although the type determination unit 68B determines that the type T2 is the type T2 among the inspected objects 20 stored in the recovery box 73. As a result, the number of inspection objects 20 accommodated in the collection box 73 is counted. The threshold setting unit 67B corrects the threshold Th so that when the ratio of the counted number exceeds 1% with respect to the total number of the inspected objects 20 accommodated in the collection box 73, the ratio becomes 1% or less. To do.

  When the threshold value Th is thus corrected, the determination unit 64B compares the corrected threshold value Th with the difference value J to determine whether the inspection object 20 is a removal target or a recovery target. It is determined whether. The sorting unit 7 removes (or collects) the inspection object 20 based on the determination result.

<Processing procedure>
FIG. 18 is a flowchart showing an example of the sorting process executed by the sorting apparatus 100B according to the seventh embodiment. Here, it is assumed that the relationship between the weighting coefficient k and the difference value J in the plurality of reference objects P1 to P3 is as shown in FIG. 10 (or FIG. 11). In addition, the inspection object 20 of the same type as the type T2 of the reference object P2 is removed, and the inspection object 20 of the same type as the other types T1, T3 is collected. The type of the inspection object 20 is assumed to be any of the types T1 to T3. In addition, it is assumed that the value of the weighting coefficient k and the value of the threshold value Th for selecting the inspection object 20 are set in advance by the method described above.

  Referring to FIG. 18, the processes of steps S602, S604, and S606 are the same as the processes of steps S502, S504, and S506 in FIG. 12, respectively, and thus detailed description thereof will not be repeated.

  The control unit 6B compares the database stored in the memory in advance with the relationship between the weight coefficient k and the difference value J in the inspection object 20, and determines the type of the inspection object 20 (step S608). Since the processes in steps S610, S612, S614, and S616 are the same as the processes in steps S508, S510, S512, and S514 in FIG. 12, detailed description thereof will not be repeated.

  Subsequently, the control unit 6B stores the determination result of the type of the inspection object 20 executed in step S608 and the determination result indicating whether the inspection object 20 executed in step S612 is a removal object or a collection object. (Step S618). Note that the control unit 6B may store the difference value J used in step S612.

  The control unit 6B determines whether or not the total number of data related to the inspection object 20 of a specified number or more (for example, 1000 or more) is accumulated as a result of totalizing the data related to the inspection object 20 stored in step S618 (step S618). S620). When the total number of data equal to or greater than the prescribed number has been accumulated (YES in step S620), control unit 6B corrects threshold value Th using the method described above (step S622), and ends the process. In this case, for the subsequent inspection object 20, the control unit 6B compares the difference value J with the corrected threshold value Th (step S612) and performs selection (steps S614 and S616).

  On the other hand, when the total data of the specified number or more is not accumulated (NO in step S620), the control unit 6B ends the process. In this case, since the threshold value Th is not corrected, the control unit 6B compares the difference value J with the current threshold value Th (step S612) and selects the subsequent inspection object 20 (step S614). , S616).

  Note that the timing for correcting the threshold Th may be a timing other than the above. For example, the control unit 6B may be configured to sequentially correct the threshold Th based on data (for example, data for the latest 1000 pieces) related to the reference number of inspection objects 20 stored most recently.

[Other embodiments]
In the above-described fourth embodiment, the determination unit 64 determines whether the inspection object 20 is a removal object or a collection object based on the determination result of the type of the inspection object 20 and a preset selection criterion. Although the configuration for determining whether or not is described, the configuration is not limited thereto. For example, the determination unit 64 executes only the determination of the type of the inspection object 20 (that is, does not determine whether the inspection object 20 is a removal object), and the information output unit 65 selects the determination result as the selection unit 7. It may be configured to output to. In this case, the sorting unit 7 sorts the inspection object 20 based on the determination result of the type of the inspection object 20 and a predetermined selection criterion.

  In addition, the determination unit 64 according to the fourth embodiment may execute the determination using the method described in the determination process in the sixth embodiment. In this case, the storage unit 63 according to the fourth embodiment stores the database used in the sixth embodiment.

  The configuration illustrated as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part of the configuration is omitted without departing from the gist of the present invention. It is also possible to change the configuration.

  In the above-described embodiment, the process and configuration described in the other embodiments may be adopted as appropriate.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2 supply unit, 3 transport unit, 4 X-ray irradiation unit, 5 X-ray detection unit, 6, 6A, 6B control unit, 7 sorting unit, 20 inspection object, 61, 61A, 61B input unit, 62, 62A, 62B Relationship calculation unit, 63, 63A, 63B storage unit, 64, 64A, 64B determination unit, 65, 65A, 65B information output unit, 66A, 66B coefficient setting unit, 67A, 67B threshold setting unit, 68B type determination unit, 69B aggregation Part, 71 air gun, 72 removal box, 73 collection box, 100, 100A, 100B sorting device.

Claims (15)

Irradiating the inspection object with X-rays to detect transmission intensity of low energy X-rays transmitted through the inspection object and transmission intensity of high energy X-rays transmitted through the inspection object;
Calculating a relationship between a difference value obtained by weighted difference of the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray and a weighting coefficient used for the weighted difference for the inspection object; Calculation method. A determination method using the calculation method according to claim 1,
Weighting the relation corresponding to the object to be inspected and the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known and different from each other A determination method including a step of determining a type of material constituting the object to be inspected based on a relationship between a difference value obtained by difference and a weighting factor used for the weighted difference. The detecting step includes
The X-ray is irradiated on the inspection object, the transmission intensity of the first energy X-ray transmitted through the inspection object, and the second energy higher in energy than the first energy X-ray transmitted through the inspection object. Detecting X-ray transmission intensity;
Irradiating the inspection object with X-rays to detect transmission intensity of third energy X-rays transmitted through the inspection object and transmission intensity of fourth energy X-rays transmitted through the inspection object; Including
The third energy X-ray has energy different from the first and second energy X-rays, the fourth energy X-ray has energy different from the first and second energy X-rays, and the third energy X-ray. Energy higher than the line,
The step of calculating the relationship includes:
For the object to be inspected, a first relationship between a difference value obtained by weighting difference between the transmission intensity of the first energy X-ray and the transmission intensity of the second energy X-ray and a weighting coefficient used for the weighting difference is calculated. Steps,
For the object to be inspected, a second relationship between a difference value obtained by weighting difference between the transmission intensity of the third energy X-ray and the transmission intensity of the fourth energy X-ray and a weighting coefficient used for the weighting difference is calculated. The calculation method of Claim 1 including a step. A determination method using the calculation method according to claim 3,
A difference value obtained by weighting a difference between the transmission intensity of the first energy X-ray and the transmission intensity of the second energy X-ray corresponding to each of a plurality of reference objects having known material types and different from each other, and the weighting difference. A first relationship with the weighting factor used;
A second value between a difference value obtained by weighting difference between the transmission intensity of the third energy X-ray and the transmission intensity of the fourth energy X-ray corresponding to each of the plurality of reference objects and a weighting coefficient used for the weighting difference. Relationship and
A determination method, comprising: determining a type of the inspection object based on the first and second relations corresponding to the inspection object.   The relationship corresponding to each of the plurality of reference objects is an average of a plurality of difference values respectively corresponding to a plurality of objects made of the same type of material as the material constituting the reference object, and a weighting factor. The determination method according to claim 2, comprising a relationship. The step of determining includes
Of the plurality of relationships corresponding to the plurality of reference objects, respectively, a relationship that is most similar to the relationship corresponding to the inspection object is identified,
The determination method according to claim 2, comprising determining that the inspection object is of the same type as a reference object corresponding to the specified relationship. The relationship corresponding to each of the plurality of reference objects is a relationship between an upper limit value based on an average value of a plurality of difference values respectively corresponding to a plurality of objects of the same type as the reference object, and a weighting factor. Including an upper limit curve, and a lower limit curve indicating a relationship between a lower limit value based on the average value and the weighting factor,
The step of determining includes
Types of materials constituting the object to be inspected based on a plurality of regions constituted by the upper limit curve and the lower limit curve respectively corresponding to the plurality of reference objects and the relationship corresponding to the object to be inspected The determination method according to claim 2, further comprising: determining A screening method using the calculation method according to claim 1,
Selecting the inspection object based on a difference value with respect to a predetermined weighting factor value in the inspection object and a threshold value;
The predetermined weight coefficient value weights the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known. Set based on the difference between the difference value and the weighting factor used for the weighted difference,
The threshold value includes a first difference value with respect to a value of the predetermined weighting factor in the designated reference object designated as a selection target among the plurality of reference objects, and the predetermined value in the remaining reference objects. A selection method that is set based on the second difference value with respect to the value of the weighting factor.   When there are a plurality of the remaining reference objects, the predetermined weight coefficient value is such that the first difference value is greater than any of the plurality of second difference values, or the first difference The selection method according to claim 8, wherein the value is set to be smaller than any of the plurality of second difference values.   The relationship corresponding to each of the plurality of reference objects includes a relationship between an average value of a plurality of difference values respectively corresponding to a plurality of objects of the same type as the reference object and a weighting factor. 9. The screening method according to 9. The relationship corresponding to each of the plurality of reference objects is a relationship between an upper limit value based on an average value of a plurality of difference values respectively corresponding to a plurality of objects of the same type as the reference object, and a weighting factor. Including an upper limit curve, and a lower limit curve indicating a relationship between a lower limit value based on the average value and the weighting factor,
The predetermined weight coefficient value corresponds to each of the plurality of reference objects, and the region corresponding to the designated reference object among the plurality of regions composed of the upper limit curve and the lower limit curve is the The selection method according to claim 8, wherein the selection method is set so as not to overlap with the region corresponding to the remaining reference object. A sorting device for sorting inspection objects,
An irradiation unit for irradiating the inspection object with X-rays;
A detection unit for detecting transmission intensity of low energy X-rays transmitted through the inspection object and transmission intensity of high energy X-rays transmitted through the inspection object;
A relation calculation unit for calculating a relation between a difference value obtained by weighting difference between the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray and a weighting coefficient used for the weighting difference for the inspection object; A sorting device. Used for the weighted difference and the difference value obtained by weighting difference between the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known. A coefficient setting unit for setting a value of a weighting coefficient for selecting the inspection object based on a relationship with a weighting coefficient;
A difference value with respect to the value of the weighting factor set by the coefficient setting unit in the designated reference object designated as a selection target among the plurality of reference objects, and a difference value with respect to the value of the weighting factor in the remaining reference objects, A threshold setting unit for setting a threshold based on
The sorting apparatus according to claim 12, further comprising: a sorting unit that sorts the inspected object based on a difference value with respect to the value of the weighting factor in the inspected object and the threshold value. A screening method using the calculation method according to claim 1,
Weighting the relation corresponding to the object to be inspected and the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known and different from each other Based on the difference between the difference value and the weighting factor used for the weighted difference, determining the type of material constituting the inspection object;
A sorting method comprising: sorting the inspected object based on a determination result of the type of material constituting the inspected object and a predetermined sorting criterion. Weighting the relation corresponding to the object to be inspected and the transmission intensity of the low energy X-ray and the transmission intensity of the high energy X-ray corresponding to each of a plurality of different reference objects whose types of materials are known and different from each other Based on the difference between the difference value and the weighting factor used for the weighted difference, determining the type of material constituting the inspection object;
Storing the determination result of the type of material constituting the inspection object and the selection result of the inspection object;
Correcting the threshold based on the determination result and the selection result in each of the plurality of inspection objects,
The step of selecting the inspection object includes a step of selecting the inspection object based on a difference value with respect to a predetermined weighting factor value in the inspection object and the corrected threshold value. The sorting method according to claim 8.

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