Foreign matter detection method and foreign matter detection device

Abstract

To provide a foreign matter detection method and a foreign matter detection device, each enabling excellent detection of even a gel having small density difference from circumferential polymer solution.SOLUTION: Foreign matter detection method for use in polymer solution comprises: irradiating the polymer solution in piping of a translucent portion 580 by the use of a first collimator lens 530 in the optical path connecting a light source 511, the first collimator lens 530, the translucent portion 580 of piping 310 in which the polymer solution flows, a second collimator lens 5301, a light reception portion 561 of an imaging apparatus 560 acquiring an image to be used for the foreign matter detection in this order; and receiving the transmitted light, transmitted through the translucent part 580, by the light reception portion 561 via the second collimator lens 5301.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a foreign matter detection method and a foreign matter detection device.

Background Art

[0002] Polymer solutions are used in the production of various industrial products. Foreign matter may be mixed in the polymer solution. Examples of foreign matter include those that enter from the outside after the synthesis of the polymer solution and those in which a part of the polymer solution has gelled. If the polymer solution containing these foreign matters is used in the production of industrial products, the quality of the products may vary, resulting in the production of non-conforming products. Therefore, it is important to manage the quality of the polymer solution by checking the presence, type, number, and size of foreign matter.

[0003] For example, Patent Document 1 proposes a method for detecting foreign matter in a solution of a polyacrylonitrile-based polymer for carbon fiber precursor fibers. In the detection method of Patent Document 1, the presence, size, and number of foreign matter in the polymer solution are detected using an image captured by irradiating light on a light-transmitting portion of a pipe through which the polymer solution is fed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the detection method of Patent Document 1, since scattered light becomes an external disturbance, a gel having a small density difference from the surrounding polymer solution cannot be detected. The present invention provides a foreign matter detection method and a foreign matter detection device that can satisfactorily detect even a gel having a small density difference from the surrounding polymer solution.

Means for Solving the Problems

[0006] The present invention has the following aspects. [1] A method for detecting foreign matter in a polymer solution, comprising: irradiating the polymer solution in the light-transmitting portion of the pipe through which the polymer solution flows with parallel light using a first collimating lens in an optical path connecting a light source, the first collimating lens, the light-transmitting portion of the pipe, the second collimating lens, and the light-receiving portion of an imaging device that acquires an image used for foreign matter detection in this order; and receiving the transmitted light that has passed through the light-transmitting portion at the light-receiving portion via the second collimating lens. A foreign matter detection method comprising the above. [2] The foreign matter detection method according to [1], further comprising passing the transmitted light through a knife edge disposed in the optical path between the second collimating lens and the light-receiving portion and receiving the transmitted light at the light-receiving portion. [3] The foreign matter detection method according to [1] or [2], using at least one or more reflection mirrors disposed in the optical path. [4] The foreign matter detection method according to any one of [1] to [3], wherein the sizes of the first collimating lens and the second collimating lens are the same and are sized to accommodate the entire width of the light-transmitting portion. [5] The foreign matter detection method according to any one of [1] to [4], wherein the light source is explosion-proof lighting, and a condenser housing connected to the explosion-proof lighting and a light guide connected to the condenser housing are used. [6] The foreign matter detection method according to any one of [1] to [5], wherein the imaging device is an explosion-proof camera. [7] The foreign matter detection method according to any one of [1] to [6], wherein the light-transmitting portion has a light-transmitting surface orthogonal to the parallel light. [8] The foreign matter detection method according to any one of [1] to [7], wherein the pipe has a branched pipe, and the branched pipe has the light-transmitting portion. [9] Correcting image blurring due to minute vibrations of the polymer solution manufacturing apparatus by performing pattern matching between frame images including at least two or more images of the same field of view; and Detecting foreign matter using a plurality of light and dark images obtained by removing the image blur by differential processing The foreign matter detection method according to any one of [1] to [8], further comprising this

[10] By comparing the light and dark image obtained by removing the image blur by differential processing from the detection image at the time when the foreign matter is detected with at least one light and dark image obtained by removing the image blur by differential processing from a frame image of at least one same field of view at a time after the time when the foreign matter is detected by a predetermined time, after determining whether the detected foreign matter is continuously detected, further counting the number of the foreign matter, The foreign matter detection method according to [9].

[11] Further comprising evaluating the type of the foreign matter by analyzing a feature amount of the light and dark image including the foreign matter determined to be continuously detected, The foreign matter detection method according to

[10] .

[0007]

[12] A foreign matter detection device in a polymer solution, A light source of a light beam irradiated to a light-transmitting part of a pipe through which the polymer solution flows, A light-receiving part of an imaging device that acquires an image used for foreign matter detection, A first collimating lens disposed in an optical path between the light source and the light-transmitting part, A second collimating lens disposed in an optical path between the light-transmitting part and the light-receiving part, A foreign matter detection device comprising this

[13] The foreign matter detection device according to

[12] , further comprising a knife edge disposed in an optical path between the second collimating lens and the light-receiving part

[14] The foreign matter detection device according to

[12] or

[13] , further comprising at least one or more reflecting mirrors disposed in the optical path

[15] The foreign matter detection device according to any one of

[12] to

[14] , wherein the sizes of the first collimating lens and the second collimating lens are the same and are sized to accommodate the entire width of the light-transmitting part

[16] The foreign object detection device according to any one of

[12] to

[15] , further comprising a condenser housing connected to the explosion-proof lighting and a light guide connected to the condenser housing, wherein the light source is explosion-proof lighting.

[17] The foreign object detection device according to any one of

[12] to

[16] , wherein the imaging device is an explosion-proof camera.

[18] The foreign object detection device according to any one of

[12] to

[17] , wherein the light-transmitting portion has a light-transmitting surface orthogonal to the parallel light traveling from the first collimating lens toward the light-transmitting portion.

[19] The foreign object detection device according to any one of

[12] to

[18] , wherein the pipe has a branched pipe, and the branched pipe has the light-transmitting portion.

[20] The foreign object detection device further comprises a processing device for analyzing the image acquired by the imaging device, wherein the processing device, a first arithmetic means for correcting image blurring due to minute vibration of the polymer solution manufacturing apparatus by performing pattern matching between frame images including at least two or more images of the same field of view; a second arithmetic means for detecting a foreign object using a plurality of light and dark images obtained by removing the image blurring detected by the first arithmetic means by differential processing; The foreign object detection device according to any one of

[12] to

[19] , having.

[21] The processing device, after determining whether the detected foreign object is continuously detected by comparing a light and dark image obtained by removing the image blurring from the detection image at the time of detecting the foreign object by differential processing with at least one light and dark image obtained by removing the image blurring from at least one frame image of the same field of view at a time after the time of detecting the foreign object by differential processing, further having a third arithmetic means for counting the number of the foreign objects. The foreign object detection device according to

[20] .

[22] The processing device, The foreign object detection device according to

[21] , further having a fourth arithmetic means for evaluating the type of the foreign object by analyzing a feature amount of the light and dark image including the foreign object determined to be continuously detected by the third arithmetic means.

Advantages of the Invention

[0008] According to the present invention, even a gel having a small density difference from the surrounding polymer solution can be detected favorably.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 6

Figure 7

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Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Modes for Carrying Out the Invention

[0010] The meanings of the terms are as follows. “Detection of foreign matter” means performing at least one confirmation selected from the group consisting of confirmation of the presence or absence of foreign matter, confirmation of the type of foreign matter, confirmation of the size of foreign matter, and confirmation of the number of foreign matters by image capture. The "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value. The numerical ranges, upper limit values, and lower limit values of the physical property values disclosed in this specification can be arbitrarily combined to form a new numerical range.

[0011] Hereinafter, several embodiments will be described with reference to the drawings as appropriate. The dimensional ratios in the drawings are for convenience of explanation and may be different from the actual ones. Also, in the drawings, the same components are denoted by the same reference numerals, and the description of overlapping components may be omitted.

[0012] FIG. 1 shows a foreign matter detection device according to a preferred example. The foreign matter detection device 100 shown in FIG. 1 includes a light source 511 of a light beam irradiated to a light-transmitting portion 580 of a pipe 310 through which a polymer solution flows, a condenser housing 512 connected to the light source 511, a light guide 513 having a first end connected to the condenser housing 512, a condenser lens 514 connected to a second end of the light guide 513, a pinhole 515, a reflection mirror 520, a reflection mirror 5201, a first collimating lens 530, a second collimating lens 5301, a reflection mirror 5202, a reflection mirror 5203, a knife edge 550, and a light receiving portion 561 of an imaging device 560 that acquires an image used for foreign matter detection. The components and devices constituting these optical systems may be generally available to those skilled in the art, and their detailed specifications and the like are not particularly limited.

[0013] The polymer solution is not particularly limited. For example, polyacrylonitrile, polycarbonate, phenol, and polymethyl methacrylate can be mentioned, but it is not limited thereto, and a solution of any polymer can be applied. Among them, a polyacrylonitrile-based polymer for carbon fiber precursor fibers is preferable.

[0014] The polyacrylonitrile-based polymer only needs to have acrylonitrile units in its molecular structure and is not particularly limited. Either a homopolymer of acrylonitrile or a copolymer of acrylonitrile and other monomers can be used. Other monomers copolymerizable with acrylonitrile are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, citraconic acid, ethacrylic acid, maleic acid, mesaconic acid, acrylamide, and methacrylamide. The other monomer may be one kind or a combination of two or more kinds. In the case of the copolymer, the content ratio of acrylonitrile units and other monomer units can be appropriately set according to the desired properties of the carbon fiber bundle to be produced.

[0015] For producing the polyacrylonitrile-based polymer, conventionally known solution polymerization, suspension polymerization, emulsion polymerization, etc. can be applied. Examples of the solvent used for preparing the polyacrylonitrile-based polymer solution include dimethyl sulfoxide, dimethylacetamide, dimethylformamide, aqueous zinc chloride solution, and nitric acid.

[0016] In the foreign matter detection device 100, an optical path L connecting the light source 511, the condenser lens 514, the pinhole 515, the reflection mirror 520, the reflection mirror 5201, the first collimating lens 530, the second collimating lens 5301, the reflection mirror 5202, the reflection mirror 5203, the knife edge 550, and the light receiving part 561 in this order is used. A light transmitting part 580 is disposed between the first collimating lens 530 and the second collimating lens 5301 of the optical path L.

[0017] The light of the light source 511 is condensed by the condenser lens 514. Thereafter, the irradiated light passes through the pinhole 515, the reflection mirror 520, and the reflection mirror 5201 in this order, and then is irradiated to the first collimating lens 530. The irradiated light becomes parallel light (collimated light) by the first collimating lens 530, and then is irradiated to the light transmitting part 580 of the pipe 310.

[0018] The transmitted light that has passed through the light-transmitting portion 580 is received by the light-receiving portion 561 after passing through the second collimating lens 5301 and the knife edge 550 in this order. The light received by the light-receiving portion 561 is converted into image information by an image sensor or the like of the imaging device 560. The image acquired by the imaging device 560 is transmitted to the processing device 563 via the LAN cable 562. The processing device 563 detects foreign matter in the polymer solution flowing in the pipe 310 by analyzing the image acquired by the imaging device 560. The imaging device 560 is not particularly limited. Preferred examples include a digital camera, a CCD camera, and a digital video camera, but an analog camera can also be used.

[0019] The foreign matter detection method according to the present embodiment includes irradiating parallel light onto the polymer solution in the pipe of the light-transmitting portion 580 using the first collimating lens 530 on the optical path L, and receiving the transmitted light that has passed through the light-transmitting portion 580 at the light-receiving portion 561 via the second collimating lens 5301. According to such a foreign matter detection method, the schlieren imaging method can be utilized. Therefore, it becomes possible to detect a gel having a small density difference from the surrounding polymer solution that cannot be detected by the naked eye.

[0020] In the foreign matter detection device 100, the light-transmitting portion 580 of the pipe 310 is disposed in the optical path between the first collimating lens 530 and the second collimating lens 5301 in the optical path L. Therefore, the schlieren imaging method can be implemented. As a result, it becomes possible to detect a gel having a small density difference from the surrounding polymer solution that cannot be detected by the naked eye.

[0021] According to the foreign matter detection method and the foreign matter detection device according to the present embodiment, the number and size of foreign matter mixed in the polymer solution can be directly detected with respect to the polymer solution in the pipe 310 which is the liquid feed line. Also, it is possible to accurately discriminate between bubbles and foreign matter generated in the solution. And since fine differences in density differences can also be distinguished from the image, even when the density difference between the solvent and the solute before mixing is small, it is also possible to inspect whether the mixing state is good or whether there is a defect.

[0022] The pipe 310 is connected to a polymerization tank for a polymerization solution of a polymer. By directly detecting foreign matters in the polymer solution within the pipe 310, the location where the foreign matters exist can be accurately grasped. When foreign matters are detected, only the polymer solution containing the foreign matters can be extracted and removed before using the polymer solution for manufacturing industrial products. Therefore, it is not necessary to stop the entire manufacturing process.

[0023] The light-transmitting part 580 is not particularly limited as long as it can irradiate the polymer solution in the pipe 310 with the light of a light source and the transmitted light can be received by the light-receiving part 561 of the imaging device 560.

[0024] In one example, the light-transmitting part 580 may be a transparent window formed on the surface of the pipe 310, or the material of the pipe 310 itself may be made transparent. That is, the light-transmitting part 580 may be provided by making a part or all of the material of the pipe 310 into a transparent pipe. In another example, for example, a device for observing the fluid in the pipe, such as a sight glass, may be provided in the pipe 310 as the light-transmitting part 580.

[0025] The material of the light-transmitting part 580 may be glass or plastic. The plastic is not particularly limited, and examples thereof include acrylic, polyethylene, polypropylene, vinyl chloride resin, polystyrene, ABS (acrylonitrile-butadiene-styrene copolymer), polyamide, polyethylene terephthalate, polycarbonate, and polyphenylene sulfide.

[0026] The shape of the light-transmitting part 580 is not particularly limited. Any polyhedron such as a circle, a square, a pentagon, or a hexagon can be used. In terms of being easy to form an image by the Schlieren imaging method, polyhedrons such as a rectangular parallelepiped and a cube are preferable. Also, it is preferable that two light-transmitting surfaces facing each other in the light-transmitting part 580 are parallel to each other.

[0027] When the light-transmitting portion 580 has a light-transmitting surface orthogonal to the parallel light traveling from the first collimating lens 530 toward the light-transmitting portion 580, the proportion of the parallel light among the transmitted light transmitted through the light-transmitting portion tends to increase. Therefore, it is easy to form an image by the Schlieren imaging method. As a result, it becomes easier to detect a gel having a small density difference from the surrounding polymer solution.

[0028] In another preferred example, the pipe 310 through which the polymer solution flows may have a branch pipe for foreign matter inspection. When this branch pipe has a light-transmitting portion, it is easy to produce the polymer solution while performing foreign matter detection.

[0029] The diameter of the pipe 310 in the light-transmitting portion 580 can be appropriately set in consideration of the brightness of the light from the light source 511, the size of the foreign matter, the flow rate of the polymer solution, and the like. For example, it can be 10 to 30 mm, 30 to 150 mm, 150 to 500 mm, or the like.

[0030] The foreign matter detection device 100 includes a knife edge 550 disposed in the optical path L between the second collimating lens 5301 and the light receiving portion 561. Therefore, in addition to the second collimating lens 5301, the transmitted light transmitted through the light-transmitting portion 580 can be received by the light receiving portion 561 via the knife edge 550 in this order. In this case, the contrast between light and dark on the image can be made clearer by narrowing the scattered light. As a result, it becomes easier to detect a gel having a small density difference from the surrounding polymer solution.

[0031] The sizes of the first collimating lens 530 and the second collimating lens 5301 are preferably the same and are such that the entire width of the light-transmitting portion 580 can be accommodated. In this case, it becomes easy to irradiate the light-transmitting portion 580 with parallel light and to receive the parallel light transmitted through the light-transmitting portion 580.

[0032] In terms of being easy to obtain a clear image, the pipe diameter of the light-transmitting portion 580 is preferably within 100 mm. In terms of being easy to obtain a clear image, the average flow rate of the polymer solution in the light-transmitting portion 580 is preferably within 200 mm / s. In terms of easily obtaining a clear image, the imaging speed of the imaging device 560 is preferably 10 fps or more.

[0033] By the way, in the method disclosed in Patent Document 1, as described in paragraph

[0028] thereof, foreign substances in the polymer solution are directly imaged with a light receiver. Therefore, there is a problem that the detection device becomes large-sized. On the other hand, the foreign substance detection device 100 includes reflection mirrors 520, 5201, 5202, and 5203 arranged in the optical path L. By using at least one or more reflection mirrors arranged in the optical path L as in this example, as shown in FIG. 2, the occupied area of the foreign substance detection device can be optimized according to the installation space. Since the installation area can also be minimized, the foreign substance detection device can be installed even in a narrow installation space.

[0034] In FIG. 1, an explosion-proof area 30 and a non-explosion-proof area 40 are shown. The optical system of the foreign substance detection device 100 is installed in the explosion-proof area 30, while the processing device 563 is arranged in the non-explosion-proof area 40. By separating and arranging the optical system and the processing system in the explosion-proof area 30 and the non-explosion-proof area 40 respectively as in this preferred example, the production of the polymer solution and the detection of foreign substances therein in the explosion-proof area 30 can be continuously carried out. Therefore, the light source 511 may be explosion-proof lighting, and the imaging device 560 may be an explosion-proof camera.

[0035] FIG. 3 shows a preferred usage example of explosion-proof lighting. As shown in FIG. 3, a condenser housing 512 provided with a light guide washer 512a is connected to the irradiation surface side of the explosion-proof lighting 511. The first end of the light guide 513 is connected to the condenser housing 512 via the light guide washer 512a. A condenser lens 514 is connected to the second end of the light guide 513. The distance from the explosion-proof lighting 511 to the light guide washer 512a is preferably within 200 mm, but it may be appropriately changed according to conditions such as light intensity and is not particularly limited.

[0036] Conventionally, when using general explosion-proof lighting as a light source, the light quantity of the irradiated light may be insufficient. This is because the generally distributed explosion-proof lighting has a small light quantity. Therefore, as shown in FIGS. 1 and 3, a condensing housing 512 connected to the explosion-proof lighting 511 and a light guide 513 connected to the condensing housing 512 can be used. By guiding light using the condensing housing 512 and the light guide 513, the influence due to insufficient light quantity can be reduced, so that general explosion-proof lighting can be utilized.

[0037] In the conventional method such as Patent Document 1, since the processing function is simple, false detection is likely to occur due to minute vibrations of the polymer solution manufacturing apparatus. As a countermeasure against this problem, the processing device 563 may detect foreign matter after correcting image blurring due to minute vibrations of the polymer solution manufacturing apparatus.

[0038] The processing device according to a preferred example includes a first calculation means for correcting image blurring due to minute vibrations of the polymer solution manufacturing apparatus by performing pattern matching between frame images including at least two or more images of the same visual field, and a second calculation means for detecting foreign matter using a plurality of light and dark images obtained by removing the detected image blurring by differential processing by the first calculation means.

[0039] As in an example shown in FIG. 4, in the first calculation, two images are acquired from a frame image including images of the same visual field (step S10). Next, pattern matching is performed by template matching such as NCC matching (step S11). Thereafter, it is determined whether the NCC score is equal to or greater than a threshold value (step S12). If the NCC score is equal to or greater than the threshold value, after correcting the deviation amount caused by image blurring due to minute vibrations of the polymer solution manufacturing apparatus (step S13), the second calculation is performed. On the other hand, if the NCC score is not equal to or greater than the threshold value, the second calculation does not have to be performed.

[0040] In the second operation, the image blur detected by the first operation is removed by differential processing to obtain a plurality of differential images (step S20). Next, the differential images are binarized to simplify the image information and obtain a light and dark image (step S21). Next, after performing morphological processing on the light and dark image (step S22), a plurality of light and dark images are used for foreign object detection (S23). Thereafter, the feature amount of the light and dark image is output (step S24). By performing the first operation and the second operation, false detection of foreign objects due to minute vibrations can be prevented.

[0041] Examples of the feature amount of the light and dark image referred to here include, but are not limited to, average luminance, luminance deviation, circularity, acicularity, and area.

[0042] The processing device according to a preferred example may further include the following third operation means in addition to the first operation means and the second operation means. The third operation means counts the number of foreign objects after determining whether the detected foreign objects are continuously detected. Therefore, it is possible to prevent double counting of foreign objects. The third operation means determines whether the foreign objects are continuously detected by comparing a light and dark image obtained by removing image blur from a detection image at the time of detecting a foreign object by differential processing with at least one light and dark image obtained by removing image blur from a frame image of at least one same field of view at a time after the time of detecting the foreign object by differential processing.

[0043] As shown in an example in FIG. 5, in the third operation, first, a foreign object information file is read in advance (step S30). Thereafter, a particle ID is assigned to each foreign object (step S31). Next, split gels and the same gels are sequentially deleted from a plurality of light and dark images (steps S32, S33). Thereafter, overlapping same gels are deleted between frame images including a plurality of light and dark images (step S34). Thereafter, by counting the number of foreign objects in the light and dark image, duplication can be prevented.

[0044] The processing device according to a preferred example may further include the following fourth arithmetic means in addition to the first arithmetic means, the second arithmetic means, and the third arithmetic means. The fourth arithmetic means evaluates the type of foreign matter by analyzing the feature amount of the light and dark image including the foreign matter determined to be continuously detected by the third arithmetic means. Therefore, it is possible to accurately determine the types of foreign matters such as gels, bubbles, and other mixtures.

[0045] As shown in an example in FIG. 5, in the fourth operation, noise is discriminated (step S41). The noise here is, for example, dust that has entered the imaging space. Then, by analyzing the feature amount of the foreign matter continuously detected, it is determined into which type, such as gel, bubble, or other mixture, the foreign matter is classified.

[0046] The results of experiments conducted by the present inventors are described below. In the experiment shown below, the Schlieren imaging method was carried out by placing a sit glass filled with a polymer solution between a pair of collimating lenses. The detailed procedure is as follows.

[0047] [Experiment 1] A test device 10 shown in FIG. 6 was constructed. In the test device 10, an optical path L connecting the explosion-proof lighting 1, the first collimating lens 2, the second collimating lens 4, the reflecting mirror 5, the knife edge 6, the condenser lens 7, and the CCD camera 8 in this order was formed. A sit glass 3 was disposed between the first collimating lens 2 and the second collimating lens 4 in the optical path L. By performing the Schlieren imaging method using the test device 10, an image of the polymer solution was obtained.

[0048] Figure 7 shows a comparison of each image when the Schlieren imaging method was implemented and when it was not. When the Schlieren imaging method was implemented, finer gels could be captured more clearly. The number of gels confirmed was 10 when the Schlieren imaging method was implemented. In contrast, when the Schlieren imaging method was not implemented, the number of gels confirmed was 8. Also, the number of bubbles was 2 when the Schlieren imaging method was implemented, while it was 1 when the Schlieren imaging method was not implemented.

[0049] [Experiment 2-6] In the test apparatus 10 shown in FIG. 6, the sight glass 3 was changed to a quartz glass container. After injecting the polymer solution into the quartz glass container, an image of the polymer solution was obtained by implementing the Schlieren imaging method. In Experiment 2, the optical path length of the quartz glass container was set to 10 mm. In Experiments 3, 4, 5, and 6, the optical path lengths of the quartz glass containers were set to 20 mm, 30 mm, 40 mm, and 50 mm, respectively.

[0050] Figures 8-12 show the results of Experiments 2-6. As is clear from comparing each image when the Schlieren imaging method was implemented and when it was not, by implementing the Schlieren imaging method even when changing the optical path length, a clear image could be obtained that could detect even fine gels.

[0051] Figure 13 shows an example of feature quantity analysis of image processing. Feature quantities were output for 381 images in which foreign objects were detected (259 gels, 92 mixtures, 30 bubbles). In this example, first, by classifying foreign objects based on whether the average luminance was 96 or more, the foreign objects could be classified as either bubbles or others. Next, classification was performed based on whether the luminance deviation was 1.423 or less. When the luminance deviation was 1.423 or less, by classifying based on whether the circularity was 0.13 or more, foreign objects could be classified into gels and mixtures. If the luminance deviation exceeded 1.423, foreign objects could be classified into mixtures. By using the threshold value, a foreign object detection rate of 90% or more could be achieved for various types. [Industrial Applicability]

[0052] According to the present invention, even a gel with a small density difference from the surrounding polymer solution can be detected well.

Explanation of Signs

[0053] 310 Pipe through which the polymer solution flows 511 Light source 530 First collimating lens 5301 Second collimating lens 560 Imaging device 561 Light receiving part 580 Light transmitting part

Claims

1. A method for detecting foreign matter in a polymer solution, in an optical path connecting a light source, a first collimating lens, a light-transmitting portion of a pipe through which the polymer solution flows, a second collimating lens, and a light-receiving portion of an imaging device for acquiring an image used for foreign matter detection in this order, irradiating parallel light onto the polymer solution in the pipe of the light-transmitting portion using the first collimating lens, and causing the transmitted light that has passed through the light-transmitting portion to be received by the light-receiving portion via the second collimating lens, A foreign matter detection method including the above.

2. The foreign matter detection method according to claim 1, further causing the transmitted light to be received by the light-receiving portion via a knife edge disposed in the optical path between the second collimating lens and the light-receiving portion.

3. The foreign matter detection method according to claim 1, using at least one or more reflection mirrors disposed in the optical path.

4. The foreign matter detection method according to claim 1, wherein the sizes of the first collimating lens and the second collimating lens are the same and are of a size that can accommodate the entire width of the light-transmitting portion.

5. The foreign matter detection method according to claim 1, wherein the light source is explosion-proof lighting, and a condensing housing connected to the explosion-proof lighting and a light guide connected to the condensing housing are used.

6. The foreign matter detection method according to claim 1, wherein the imaging device is an explosion-proof camera.

7. The foreign matter detection method according to claim 1, wherein the light-transmitting portion has a light-transmitting surface orthogonal to the parallel light.

8. The foreign matter detection method according to claim 1, wherein the pipe has a branched pipe, and the branched pipe has the light-transmitting portion.

9. By performing pattern matching between frame images including at least two or more images of the same visual field, correcting image blur due to minute vibrations of the manufacturing apparatus for the polymer solution, and detecting foreign matter using a plurality of light and dark images obtained by removing the image blur by differential processing, The foreign matter detection method according to claim 1, further comprising:

10. By comparing at least one light and dark image obtained by removing the image blur by differential processing from a detection image at the time of detecting foreign matter with at least one light and dark image obtained by removing the image blur by differential processing from at least one frame image of the same visual field at a time after a predetermined time from the time of detecting foreign matter, after determining whether the detected foreign matter is continuously detected, further counting the number of the foreign matter, The foreign matter detection method according to claim 9.

11. The foreign matter detection method according to claim 10, further comprising evaluating the type of the foreign matter by analyzing a feature amount of the light and dark image including the foreign matter determined to be continuously detected.

12. A foreign matter detection device in a polymer solution, a light source of a light beam irradiated to a light-transmitting portion of a pipe through which the polymer solution flows, a light-receiving portion of an imaging device that acquires an image used for foreign matter detection, a first collimating lens disposed in an optical path between the light source and the light-transmitting portion, a second collimating lens disposed in an optical path between the light-transmitting portion and the light-receiving portion, A foreign matter detection device comprising:

13. The foreign matter detection device according to claim 12, further comprising a knife edge disposed in an optical path between the second collimating lens and the light-receiving portion.

14. The foreign matter detection device according to claim 12, further comprising at least one or more reflecting mirrors disposed in the optical path.

15. The size of the first collimating lens and the second collimating lens is the same and is sized to fit within the entire width of the light-transmitting portion. The foreign object detection device according to claim 12.

16. The light source is explosion-proof lighting, and further includes a condenser housing connected to the explosion-proof lighting and a light guide connected to the condenser housing. The foreign object detection device according to claim 12.

17. The imaging device is an explosion-proof camera. The foreign object detection device according to claim 12.

18. The light-transmitting portion has a light-transmitting surface orthogonal to the parallel light traveling from the first collimating lens toward the light-transmitting portion. The foreign object detection device according to claim 12.

19. The pipe has a branched pipe, and the branched pipe has the light-transmitting portion. The foreign object detection device according to claim 12.

20. Further includes a processing device for analyzing the image acquired by the imaging device, The processing device, By performing pattern matching between frame images including at least two or more images of the same field of view, a first arithmetic means for correcting image blur due to minute vibrations of the polymer solution manufacturing apparatus; A second arithmetic means for detecting foreign objects using a plurality of light and dark images obtained by removing the image blur detected by the first arithmetic means by differential processing; The foreign object detection device according to claim 12, which has

21. The processing device, By comparing a light and dark image obtained by removing the image blur from the detection image at the time of detecting a foreign object by differential processing with at least one light and dark image obtained by removing the image blur from at least one frame image of the same field of view at a time after a predetermined time from the time of detecting the foreign object by differential processing, after determining whether the detected foreign object is continuously detected, further having a third arithmetic means for counting the number of the foreign objects. The foreign object detection device according to claim 20. Claim 22 wherein the processing device further comprises fourth arithmetic means for evaluating the type of the foreign matter by analyzing a feature amount of the light and dark image including the foreign matter, which is determined to be continuously detected by the third arithmetic means, the foreign matter detection device according to claim 21.

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