Foreign substance detection device for recycled plastic material

Abstract

The present invention relates to a foreign substance detection device for a recycled plastic material, wherein light is emitted toward a test sample made of a recycled plastic material in a state in which a reflection plate is disposed on the bottom surface of a sample holder on which the test sample is placed, thereby improving the clarity of foreign substances included in the test sample so that the accuracy of foreign substance evaluation can be improved.

Description

Foreign matter detection device for recycled plastic materials

[0001] This invention claims the benefit of Korean Patent Application No. 10-2023-0162261 filed with the Korean Intellectual Property Office on November 21, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a foreign matter detection device for recycled plastic materials, which can improve the clarity of foreign matters contained in recycled (PCR, Post-Consumer Recycled) plastic materials and thereby increase the accuracy of foreign matter evaluation.

[0003]

[0004] Typically, to assess the quality of plastic materials, a pancake-shaped product is manufactured. The size and number of foreign particles contained within the product are then assessed, assigning a foreign material score. Currently, most workers perform visual foreign material assessments.

[0005] Specifically, for new plastic products, the number of foreign substances is not large, so it is possible to visually determine whether there are foreign substances in the product and then measure the size of the foreign substances to assign a foreign substance score.

[0006] However, in the case of recycled plastic products, the amount of foreign matter is greater than in new plastic products, making visual inspection impossible.

[0007] Additionally, when acquiring and inspecting an image of a recycled plastic plate, there is a problem in that the clarity of the foreign matter is poor, making it difficult to measure its exact size.

[0008] ※ Patent Document 1: Republic of Korea Patent Publication No. 10-2023-0063933 (Published: May 10, 2023)

[0009]

[0010] The present invention is intended to solve the above-described problem, and the purpose of the present invention is to provide a foreign matter detection device for recycled plastic materials, which improves the clarity of foreign matters contained in the sample to be inspected and increases the accuracy of foreign matter evaluation by irradiating light toward the sample to be inspected while a reflector is placed on the bottom of a sample holder on which the sample to be inspected of recycled plastic materials is placed.

[0011]

[0012] In order to achieve the above-described purpose, a foreign matter detection device according to the present invention may include a sample holder on which a sample to be inspected is placed; an illumination unit that irradiates light toward the sample to be inspected on the sample holder; a reflection unit that is provided with a reflection plate that is disposed on an opposite side of the illumination unit with respect to the sample holder and reflects the light irradiated by the illumination unit toward the sample to be inspected; a photographing unit that photographs the sample to be inspected to obtain an image; and an evaluation unit that determines whether there is a foreign matter inside the sample to be inspected and the size and number of the foreign matters based on image information obtained from the photographing unit.

[0013] In this case, the sample holder may be configured to transmit light irradiated from the lighting unit.

[0014] In addition, the lighting unit may include a unit spaced apart on both sides with the photographing unit in between.

[0015] In addition, the photographing unit may be installed so as to be able to reciprocate together with the lighting unit along one side of the longitudinal direction of the sample holder, and may include photographing the sample to be inspected in a line scan manner.

[0016] In addition, a prism film may be further interposed between the sample holder and the reflector to focus light reflected from the reflector onto the sample to be inspected.

[0017] In addition, the prism film may include a first film laminated on the upper surface of the reflector and having a prism structure arranged in a vertical direction; and a second film laminated on the upper surface of the first film and having a prism structure arranged in a horizontal direction.

[0018] In addition, the evaluation unit may include an image processing process that displays the shape of the foreign object by setting a boundary along the edge of the foreign object in the photographed image.

[0019] Additionally, the brightness (luminance) of the above reflector may include 90 to 100L based on a maximum value of 100L.

[0020] Additionally, the above test subject sample can be manufactured from recycled plastic.

[0021]

[0022] The foreign matter detection device for recycled plastic materials according to the present invention having the above configuration can improve the clarity of foreign matters contained in the sample to be inspected by irradiating light toward the sample to be inspected and reflecting it through the reflector while a reflector is placed on the bottom surface of the sample holder on which the sample to be inspected of the recycled plastic material is placed, thereby increasing the accuracy of foreign matter evaluation.

[0023] In particular, by interposing a prism film between the sample holder and the reflector and setting the brightness of the reflector to an optimal level, the boundary of the foreign matter can be clearly displayed.

[0024]

[0025] Figure 1 is a perspective view showing one embodiment of a foreign matter detection device for recycled plastic materials according to the present invention;

[0026] Figure 2 is a front view of Figure 1;

[0027] Figure 3 is a perspective view showing a state in which a prism film is interposed between a sample holder and a reflector according to the present invention.

[0028] Figure 4 is a front view of Figure 3;

[0029] Figure 5 is an exploded perspective view showing a structure in which a prism film is laminated on the upper surface of the reflector of Figure 3.

[0030] Figure 6 is an image processing result when a prism film according to the present invention is applied.

[0031] Figure 7 is a state diagram of foreign substances 1 and 2 detected by a foreign substance detection device according to the present invention, measured under a microscope.

[0032] Figure 8 is a state diagram of the foreign body 1 of Figure 7 processed using the reflectors of Examples 1 to 4.

[0033] Figure 9 is a state diagram of the image processing of the foreign substance 2 of Figure 7 using the reflectors of Examples 1 to 4.

[0034] Figure 10 shows the difference in image processing results when a prism film according to the present invention is applied.

[0035] ※ Explanation of symbols

[0036] P: Test target sample 100: Foreign matter detection device

[0037] 110: Sample holder 120: Lighting unit

[0038] 130: Reflector 131: Reflector

[0039] 140: Filming section 150: Prism film

[0040] 151: First film 153: Second film

[0041]

[0042] The configuration and operation of a specific embodiment of the present invention will be described in detail with reference to the attached drawings.

[0043] Here, when adding reference signs to components of each drawing, it should be noted that identical components are indicated with the same signs as much as possible even if they are shown in different drawings.

[0044] FIG. 1 is a perspective view showing one embodiment of a foreign matter detection device for recycled plastic materials according to the present invention.

[0045] Referring to FIG. 1, a foreign matter detection device (100) for recycled plastic materials according to a preferred embodiment of the present invention may include a sample holder (110), a lighting unit (120), a reflecting unit (130), a photographing unit (140), and an evaluation unit (not shown).

[0046] The composition of the present invention is described in detail as follows.

[0047]

[0048] First, the sample holder (110) can be formed with a predetermined area so that a test sample (P) formed into a pancake shape using recycled plastic material can be placed on the upper surface.

[0049] In this case, the sample holder (110) may be formed of a transparent glass material so that light irradiated from the lighting unit (120) described later can be transmitted therethrough. Of course, this is not limited to this, and the material of the sample holder (110) may be changed and applied in various ways as long as it can easily transmit light.

[0050] In addition, in the present invention, an example in which the inspection target sample (P) is formed in a circular shape has been described, but the present invention is not limited thereto, and the inspection target sample (P) may be changed to a square or polygonal shape.

[0051]

[0052] Referring to FIG. 2, the lighting unit (120) is positioned at a predetermined height above the sample holder (110) to irradiate light toward the sample (P) to be inspected.

[0053] Specifically, the lighting unit (120) may be arranged symmetrically on both sides of the center of the sample holder (110) on which the sample to be inspected (P) is placed, i.e., the position where the photographing unit (140) to be described later is arranged. This lighting unit (120) may irradiate light downward toward the sample to be inspected (P) and transmit it.

[0054]

[0055] The above reflector (130) is placed on the opposite side of the lighting unit (120) with respect to the sample holder (110), so as to reflect the light irradiated from the lighting unit (120) toward the sample (P) to be inspected.

[0056] Specifically, the reflector (130) may include a reflector (131) disposed on the bottom surface of the sample holder (110). This reflector (131) may reflect light that is irradiated downward from the lighting unit (120) and passes through the sample (P) to be inspected back to the upper side where the sample (P) to be inspected is placed. Accordingly, when the sample (P) to be inspected is viewed in a flat plane, foreign substances present inside the sample (P) can be clearly displayed.

[0057] In this case, the degree to which the reflector (131) reflects light may vary depending on the brightness (luminance). Therefore, in the present invention, it is preferable to use a reflector (131) with a brightness of 90 to 100L based on a maximum brightness of 100L.

[0058] That is, if the brightness of the reflector (131) is less than 90L, the reflection efficiency may decrease, and accordingly, it may be difficult to detect foreign substances when measuring foreign substances in the evaluation section described later, or even if the foreign substances are detected, an error may occur compared to the actual size of the foreign substances.

[0059]

[0060] The above-mentioned photographing unit (140) is installed at a distance from the upper side of the sample holder (110) and can obtain an image showing foreign substances by photographing the inspection target sample (P) through which light is transmitted by the lighting unit (120) and the reflecting unit (130).

[0061] Specifically, the above-mentioned photographing unit (140) may be installed so as to be able to reciprocate together with the lighting unit (120) along one side of the longitudinal direction of the sample holder (110) by receiving power. The photographing unit (140) and the lighting unit (120) may move along one side of the longitudinal direction of the sample holder (110) to photograph the sample (P) to be inspected in a line scan manner.

[0062] In addition, the above-mentioned photographing unit (140) and lighting unit (120) can be formed with a length corresponding to the width of the sample holder (110) on which the sample to be inspected (P) is placed so as to enable line scan photography.

[0063] In this case, the present invention has described an example in which the sample holder (110) is fixed and the photographing unit (140) and the lighting unit (120) move while photographing the sample to be inspected (P) in a line scan manner. However, conversely, the method may be changed to a method in which the sample holder (110) moves while the positions of the photographing unit (140) and the lighting unit (120) are fixed.

[0064] In addition, there is no particular limitation on the components required for the reciprocating movement of the above-mentioned photographing unit (140), lighting unit (120), or sample holder (110).

[0065]

[0066] The above evaluation unit can detect whether there is a foreign substance inside the test target sample (P) and the size and number of the foreign substances based on the image information captured by the shooting unit (140).

[0067] In this case, the evaluation unit may perform an image processing process on the foreign matter portion included in the inspection target sample (P) in the captured image.

[0068] Specifically, the image processing process may include a process of accurately displaying the shape of a foreign object by setting a boundary along the edge of the foreign object in the captured image. Accordingly, the clarity of the foreign object within the inspection target sample (P) can be improved, and through this process, the detection efficiency of the foreign object can be improved.

[0069]

[0070] Fig. 3 is a perspective view showing a state in which a prism film is interposed between a sample holder and a reflector according to the present invention, and Fig. 4 is a front view of Fig. 3.

[0071] Referring to FIGS. 3 and 4, a prism film (150) may be interposed between the sample holder (110) and the reflector (131). The prism film (150) has a structure in which a micro-prism structure is formed on the surface, and may be formed of polycarbonate (PC), polyester (PET), or the like, for example. Accordingly, when light is irradiated from the lighting unit (120) and then reflected from the reflector (131), the scattered light is focused on the sample (P) to be inspected, thereby increasing the straightness and enhancing the brightness of the light. As a result, the intensity of the light irradiated to the sample (P) to be inspected can be maximized, thereby improving the clarity of foreign substances in the sample (P) to be inspected.

[0072] Specifically, the prism film (150) may include a first film (151) laminated on the upper surface of the reflector (131) and having a prism structure arranged in a vertical direction, and a second film (153) laminated on the upper surface of the first film (151) and having a prism structure arranged in a horizontal direction (see FIG. 5).

[0073] That is, by first focusing the light from the first film (151) and second focusing it again from the second film (153), the light reflected upward from the reflector (131) can be focused toward the test sample (P) placed on the sample holder (110) without being scattered in all directions.

[0074] As a result of applying the prism film (150) of this structure, as shown in Fig. 6, the image processing result of foreign matter when the prism film (150) is applied is similar to the actual measured result, and the detected foreign matter can be displayed more clearly compared to the existing configuration without the prism film (150).

[0075]

[0076] Hereinafter, a process of detecting foreign substances using a foreign substance detection device (100) for recycled plastic materials according to the present invention having the above configuration will be described.

[0077] First, a circular-shaped test sample (P) is placed on the upper surface of the sample holder (110), and then light of a predetermined brightness is irradiated toward the test sample (P) from a pair of lighting units (120) spaced apart from each other on the upper side of the sample holder (110) (see FIG. 4).

[0078] In this case, the light irradiated from the lighting unit (120) is reflected upward by the reflector (131) on the lower side of the sample holder (110) and can be focused on the sample (P) to be inspected while passing through the prism film (150). Accordingly, the intensity of the reflected light can be maximized, thereby improving the clarity of foreign substances in the sample (P) to be inspected.

[0079] In addition, the lighting unit (120) and the photographing unit (140) move back and forth along one side of the length of the sample holder (110) to photograph the test target sample (P) placed on the sample holder (110) in a line scan manner.

[0080] And the evaluation department determines whether there is a foreign substance inside the test sample (P) based on the image information captured by the shooting department (140).

[0081] If a foreign substance is found in the test sample (P) as a result of the judgment of the above evaluation department, an image processing process is performed to accurately display the shape of the foreign substance by setting a boundary along the edge of the foreign substance.

[0082] After that, based on the image processing results, the size and number of foreign substances inside the test sample (P) are measured and a foreign substance score is assigned.

[0083]

[0084] <Experimental Example 1>

[0085] An experiment was conducted to detect and evaluate the presence of foreign substances and the size and number of foreign substances in a sample (P) to be inspected using the foreign substance detection device (100) for recycled plastic materials of the present invention.

[0086] Specific experimental conditions were such that the settings of the photographing unit (140) and the lighting unit (120) constituting the foreign substance detection device (100) were the same, and the brightness (luminance) (L) of the reflector (131) applied to the reflector (130) was applied differently as in Examples 1 to 4 of [Table 1] below.

[0087]

[0088] Reflector (131) Brightness (L) Example 122.1 Example 26.6 Example 387.1 Example 497.1

[0089]

[0090] In this case, foreign substances 1 and 2 were detected, for example, in the test target sample (P) (see Fig. 7), and foreign substance evaluation was performed based on images taken under the same brightness (L) conditions of the reflector (131) as Examples 1 to 4 of [Table 1].

[0091] As a result, as shown in FIGS. 8 and 9, the images of foreign substances 1 and 2 were processed, and the boundary of the foreign substances was most clearly seen at the brightness of the reflector (131) of Example 4.

[0092] In addition, when comparing the actual size measurement results of foreign substances 1 and 2 as shown in [Table 2] below with the sizes of foreign substances 1 and 2 measured through the images of Examples 1 to 4 through the evaluation section, it was found that the evaluation results of Example 4, in which the errors with the actual measurement results of foreign substances 1 and 2 were 0% and 3%, respectively, were the most similar.

[0093]

[0094] Actual measurement (mm) Example 1 Example 2 Example 3 Example 4 Foreign matter 10.856-0.625 (27%) 0.869 (2%) 0.857 (0%) Foreign matter 20.701-0.364 (48%) 0.744 (6%) 0.726 (3%)

[0095]

[0096] <Experimental Example 2>

[0097] An experiment was conducted to detect and evaluate the presence of foreign substances in a sample (P) to be inspected and the actual measured value and number of foreign substances using the foreign substance detection device (100) for recycled plastic materials of the present invention.

[0098] Specific experimental conditions were applied in such a way that the settings of the photographing unit (140) and the lighting unit (120) constituting the foreign substance detection device (100) were the same, a sample having an actual measured value of 0.799 mm of the foreign substance was prepared, and the presence or absence of the prism film (150) applied to the reflecting unit (130) was applied differently.

[0099] As shown in (a) of Fig. 10, when an image of a foreign substance is processed, the presence of a fine foreign substance can be recognized when equipped with a prism film, and the size of the foreign substance can be recognized as 0.829 mm, so there is an effect of being able to detect the foreign substance more easily.

[0100] On the other hand, as shown in (b) of Fig. 10, when the image of the foreign substance is processed and the prism film is not provided, it can be confirmed that the possibility of recognizing the presence of a fine foreign substance is somewhat lower, and thus, the foreign substance may not be measured.

[0101] As a result, when a prism film (150) is applied to the foreign matter detection device (100) for recycled plastic materials of the present invention, there is an effect of more easily detecting unclear foreign matters that are difficult to detect with the naked eye.

[0102]

[0103] Although the present invention has been described and illustrated with specific embodiments above, the present invention is not limited to the above-described embodiments, and various changes and modifications are possible within a scope that does not depart from the technical spirit of the present invention.

Claims

1. Sample holder on which the sample to be tested is placed; A lighting unit that irradiates light toward the test subject sample on the sample holder; A reflection unit having a reflector disposed on the opposite side of the lighting unit with respect to the sample holder to reflect light irradiated from the lighting unit toward the sample to be inspected; A photographing unit that photographs the above-mentioned test subject sample to obtain an image; and A foreign matter detection device including an evaluation unit that determines whether there is a foreign matter inside the inspection target sample and the size and number of the foreign matters based on the image information acquired from the above photographing unit.

2. In paragraph 1, The above sample holder is, A foreign matter detection device configured to transmit light irradiated from the above lighting unit.

3. In paragraph 1, The above lighting unit, A foreign body detection device including a device spaced apart on both sides with the above-mentioned photographing section in between.

4. In paragraph 1 or paragraph 3, The above filming department, A foreign matter detection device including a lighting unit that is installed so as to be reciprocally movable along one side of the longitudinal direction of the sample holder, and that photographs the sample to be inspected using a line scan method.

5. In paragraph 1, Between the above sample holder and the reflector, A foreign matter detection device further comprising a prism film that focuses light reflected from the reflector onto the test sample.

6. In paragraph 5, The above prism film, A first film laminated on the upper surface of the above reflector, wherein the prism structure is arranged in a vertical direction; and A foreign matter detection device comprising a second film laminated on the upper surface of the first film and having a prism structure arranged in a horizontal direction.

7. In paragraph 1, The above evaluation department, A foreign matter detection device including an image processing process for displaying the shape of a foreign matter by setting a boundary along the edge of the foreign matter in the captured image.

8. In paragraph 1, The brightness (luminance) of the above reflector is A foreign body detection device including 90 to 100 L with a maximum of 100 L as the standard.

9. In paragraph 1, The above test target sample is, A foreign body detection device manufactured from recycled plastic.

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