Optical foreign body detection device using light scattering and image analysis

Abstract

The present invention provides an optical foreign body detection device that uses light scattering and image analysis to detect and analyze foreign bodies contained in an object, the optical foreign body detection device including: an optical housing; a light irradiation unit that is connected to a lower part of the optical housing and has a plurality of light sources disposed therein and irradiates light toward the object below, the light sources irradiating light with a predetermined amount of light so that light scattering can be caused by foreign bodies; an optical unit that is built into an upper part of the optical housing and captures an image of the object to detect foreign bodies contained in the object using light scattering of the foreign bodies caused by the light irradiated from the light sources; and a user device that receives, stores, plays back, and analyzes the image generated by the optical unit.

Description

[Technical Field]

[0001] The present invention relates to an optical foreign object detector, and more particularly to an optical foreign object detector that can detect and analyze foreign objects by combining light scattering and image analysis to identify the size, shape, area, color, etc. of the foreign object, has a high processing speed for foreign object detection and image analysis, and is capable of detecting foreign objects smaller than the pixel limit. [Background technology]

[0002] Generally, as industries become more advanced, the need to control foreign matter such as dust increases not only in office environments but also in production sites, and clean rooms have been introduced to keep production sites clean and prevent foreign matter from adversely affecting products.

[0003] In particular, in cutting-edge industries such as semiconductors and displays, which involve highly precise manufacturing processes at the nano level, even minute environmental conditions at the manufacturing site can have a significant impact on the quality of the product, so the level of cleanliness required in clean rooms is becoming increasingly strict.

[0004] Displays are used in areas such as mobile phones, tablet PCs, monitors, home appliances, and automotive electronic devices, and are made from OCA film, polarizing film, glass, etc. If foreign particles of a certain size or larger are present in such display films, it can cause pixel defects or a deterioration in image quality. In addition, if foreign particles of a certain size or larger are present in various films used in building glass windows and interiors, product defects can occur.

[0005] Conventional foreign matter detectors for detecting such foreign matter measure particle concentration by irradiating a sample with light and using the scattered light scattered by the foreign matter. The scattered light is focused on a light receiving unit either directly or after being reflected by a mirror, and the amount of focused light is measured using an electrical signal to determine the number and approximate size of the foreign matter. However, this type of foreign matter detector has the problem of not being able to determine the type, actual size, shape, major and minor axis lengths, area, or color of the foreign matter.

[0006] Furthermore, although foreign matter can be detected using an optical microscope, such a device can determine the actual size, shape, area, color, etc. of the foreign matter, but has the problem of difficulty in detecting foreign matter that is smaller than the limit of the detectable pixels of the image sensor connected to the optical microscope, and requires a long detection time.

[0007] As related prior art, Korean Patent Publication No. 10-2020-0052157 (published on May 14, 2020) discloses a digital microscope that includes a stage on which a sample is placed, a low-magnification optical module that images the sample and generates a low-magnification image, a high-magnification optical module that images the sample and generates a high-magnification image and is located on the opposite side of the low-magnification optical module relative to the sample, a driving module that moves the high-magnification optical module, and a user device that reproduces the low-magnification image and the high-magnification image, and in which the imaging area of the high-magnification optical module is changed by driving the driving module.

[0008] However, the above-mentioned conventional technology has problems in that it is difficult to detect small foreign particles because it uses direct light, and when multiple foreign particles are present, the detection time is long. In addition, since the entire area of the sample must be grasped using a low-magnification image and then a high-magnification optical module must be moved to the area where the foreign particle is detected for detailed observation, the detection time is long, the operation is complicated, and the equipment is large and takes up a lot of space.

[0009] Furthermore, the above-mentioned conventional techniques require a sample to be placed on a stage for observation, and because the stage must always be available, there are limitations on the type, size, and weight of the sample that can be placed on the stage, making it difficult to carry or move the entire apparatus for use. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been devised to solve all of the above problems, and its object is to provide an optical foreign body detection device that uses light scattering and image analysis in combination to quickly detect and analyze foreign bodies to determine the actual size, shape, area, color, etc. of the foreign body, and to determine the path of the foreign body, enabling contamination control in a clean room. It also has a fast processing speed for foreign body detection and image analysis, is capable of detecting foreign bodies smaller than the pixel limit of an image sensor, prevents foreign body detection errors, and is highly reliable. It can be placed on an object without a stage, is portable, and can be easily moved to the object for use. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides an optical foreign body detection device that uses light scattering and image analysis to detect and analyze foreign bodies contained in an object, comprising: an optical housing; a light irradiation unit that is connected to and installed at the bottom of the optical housing and has a plurality of light sources arranged therein and irradiates light toward the object below, the light sources irradiating light with a predetermined amount of light so that light scattering can be caused by foreign bodies; an optical unit that is built into the top of the optical housing and captures an image of the object to detect foreign bodies contained in the object using light scattering of foreign bodies caused by the light irradiated from the light sources; and an optical unit that receives, stores, reproduces, and analyzes the image generated by the optical unit. the user device calculates amplification length values of standard particles scattered by light by irradiating a large number of standard particles with light according to their standard particle length values, creates a graph showing the correlation between the standard particle length values and the amplification length values of the standard particles, and stores the graph as a comparison standard for the length values of the foreign particles; calculates amplification length values of foreign particles scattered by light in one or more directions for the foreign particles detected from an image of the object captured by the optical unit; derives standard particle length values corresponding to the amplification length values of standard particles identical to the amplification length values of the foreign particles from the comparison standard, and determines the foreign particle length values as the length values of the foreign particles; and determines the size, shape, and area of the foreign particles from the length values of the foreign particles. [Effects of the Invention]

[0012] According to the present invention, by using a combination of light scattering and image analysis, it is possible to detect and analyze foreign matter, and to confirm the actual size, shape, area, color, etc. of the foreign matter, and to determine the path of the foreign matter, thereby enabling contamination control in a clean room. It also has the advantages of fast processing speed for foreign matter detection and image analysis, being able to detect foreign matter smaller than the pixel limit of the image sensor, preventing foreign matter detection errors and providing high reliability, and being portable and able to be used by being placed on the target without a stage, allowing it to be easily moved to the target for use. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a diagram showing the configuration of an optical foreign matter detection device according to an embodiment of the present invention; [Figure 2a] 1 is a perspective view of an optical foreign matter detection device according to an embodiment of the present invention; [Figure 2b] FIG. 2 is a bottom view of the optical foreign matter detection device according to the embodiment of the present invention. [Figure 2c] 1 is a diagram illustrating a state in which an optical foreign matter detection device according to an embodiment of the present invention is used; [Figure 3a] 1 is a diagram showing an arrangement of a light irradiation unit according to an embodiment of the present invention; [Figure 3b] 1 is a diagram showing an arrangement of a light irradiation unit according to an embodiment of the present invention; [Figure 4a] 1 is a graph showing a correlation of the scattered amplification ratio of a standard particle with the length value of the standard particle according to an embodiment of the present invention; [Figure 4b] 1 is a graph showing a correlation between standard particle length values and standard particle amplification length values according to an embodiment of the present invention; [Figure 5a] 1A and 1B are diagrams illustrating a part of a light scattering image according to the size and shape of a foreign particle according to an embodiment of the present invention. [Figure 5b] 1A and 1B are diagrams illustrating a part of a light scattering image according to the size and shape of a foreign particle according to an embodiment of the present invention. [Figure 5c] 1A and 1B are diagrams illustrating a part of a light scattering image according to the size and shape of a foreign particle according to an embodiment of the present invention. [Figure 5d] 1A and 1B are diagrams illustrating a part of a light scattering image according to the size and shape of a foreign particle according to an embodiment of the present invention. [Figure 6] 1 is a flowchart illustrating a detection and analysis method for an optical foreign matter detection device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The optical foreign matter detection device 1 according to the present invention uses a combination of light scattering and image analysis to detect and analyze foreign matter F contained in an object M such as a film, substrate, panel, or equipment, and can identify the size, shape, area, and color of the foreign matter F. The device has a fast processing speed for foreign matter detection and image analysis, is capable of detecting foreign matter smaller than the pixel limit, and can be placed on the surface of the object M without a stage. Referring to FIG. 1, the device includes an optical housing 100, a light irradiation unit 200, an optical unit 300, and a user device 400, and may further include a foreign matter type analyzer (not shown).

[0015] 2a to 2c, the optical housing 100 according to an embodiment of the present invention has an optical unit 300 built in an upper portion, a light irradiation unit 200 connected to a lower portion, a light scattering part 110 formed between the optical unit 300 and the light irradiation unit 200, and a handle 120 formed on the exterior for easy portability and transportation. The optical housing 100 may be provided with an adjustment means (not shown) for adjusting the focal length of the optical unit 300.

[0016] The light scattering unit 110 provides a darkroom inside, and allows light to be irradiated from a plurality of light sources 210 of the lower light irradiation unit 200, scattered by foreign matter F contained in the target M, and then received by the optical unit 300. For this purpose, the light scattering unit 110 is formed so that its diameter gradually decreases toward the upper side and converges into the light irradiation unit 200. When a user holds the handle 120 and places the optical housing 100 on the surface of the target M, a darkroom is formed in the light scattering unit 110, and the surface of the target M corresponding to the inner diameter of the light irradiation unit 200 becomes the detection area.

[0017] Referring to FIG. 3a, the light irradiation unit 200 is connected to and installed at the bottom of the optical housing 100, and has a plurality of light sources 210 arranged thereon to irradiate light from the side toward the detection area of the object M below. The light sources 210 irradiate light with a predetermined amount of light so that light scattering can occur due to foreign matter F contained in the object M. The optical unit 300 can generate an image including scattered light whose magnitude has been amplified by scattering due to foreign matter F, and the user device 400 detects and analyzes the foreign matter F contained in the object M.

[0018] In one embodiment, the light irradiation unit 200 includes a ring-shaped light irradiation ring 220 connected to a lower portion of the light scattering portion 110 so as to protrude outward. The light irradiation ring 220 has an internal storage space and a through-hole formed therein, the through-hole having the same inner diameter as the lower portion of the light scattering portion 110. A plurality of light sources 210 are symmetrically arranged along the storage space within the light irradiation ring 220 to irradiate light with a predetermined amount of light from a plurality of directions toward the object M. The plurality of light sources 210 may be symmetrically arranged in a plurality of directions, such as four, six, eight, ten, twelve, fourteen, or sixteen directions, to irradiate light toward the detection area of the object M. A light diffusion plate (not shown) may be installed in front of the light sources 210 to increase the uniformity of the light distribution.

[0019] Furthermore, a contact ring 230 is attached to the bottom of the light irradiation ring 220 to tightly contact the surface of the object M, thereby preventing external light from entering the inside of the optical housing 100 and causing interference, thereby providing a darkroom.

[0020] As an example, the adhesion ring 230 may contain, by weight, 30 to 50% polyphenylene sulfide resin, 15 to 25% SBR, 10 to 20% polyurethane resin, 10 to 20% polymethyl methacrylate, 5 to 10% 2-mercaptoadenine, and 1 to 5% light absorber.

[0021] The polyphenylene sulfide resin is a semi-crystalline thermoplastic resin produced by the reaction of p-dichlorobenzene and sodium sulfide. It offers excellent heat resistance, chemical resistance, and durability, as well as excellent mechanical strength. It is typically added at 30 to 50% by weight. The SBR is a styrene-butadiene synthetic rubber that offers excellent strength and abrasion resistance, is elastic, and provides friction to contact surfaces. It is typically added at 15 to 25% by weight. The polyurethane resin provides strength by maintaining flexibility while remaining hard, preventing cracking, and exhibits a sticky phase to increase adhesion and provide excellent stain resistance. When added together with the polyphenylene sulfide resin and SBR, it significantly improves physical properties such as elasticity, viscosity, toughness, and durability, resulting in a significant improvement in the modifying effect. It is typically added at 10 to 20% by weight. The polymethyl methacrylate enhances interparticle bonding with its excellent viscosity and adhesive strength. It is typically added at 10 to 20% by weight. The 2-mercaptoadenine, which is added at 5 to 10% by weight, has needle-shaped microcrystals and forms a stable and dense coating film over the long term, improving watertightness, suppressing cracks, contributing to stable strength enhancement, and preventing oxidation caused by exposure to air and light.The light absorber, which is added at 1 to 5% by weight, absorbs light to prevent reflection and increase detection accuracy.

[0022] Furthermore, if light is irradiated only from one side of the detection area of the object M and multiple foreign objects F are included in the detection area of the object M, a shaded section may occur behind any one foreign object F, which may make it difficult to adequately detect other adjacent foreign objects F. In the present invention, multiple light sources 210 are arranged symmetrically around the detection area of the object M on which the optical housing 100 is placed, and irradiate light from multiple directions with a predetermined amount of light toward the detection area of the object M, thereby preventing the overlooking of detection of foreign objects F due to the shaded section and improving detection reliability. In this case, the light sources 210 may be LEDs, lasers, etc.

[0023] In addition, the light irradiation unit 200 preferably has a light irradiation angle of 1 to 60 degrees from the light source 210 to the object M. When the light emitted from the light source 210 is reflected by a foreign object F, light scattering occurs, which spreads the light. This increases the size of the detection that the image sensor of the optical unit 300 can accept, thereby increasing the detection power. This allows the foreign object F to be quickly detected and analyzed from the image captured by the optical unit 300, and foreign objects F that are smaller than the size detectable by the optical unit 300 or that do not reflect light well can also be detected. If the light irradiation angle exceeds 60 degrees, the effect of increasing the detection power due to light scattering when the light is reflected by the foreign object F may be reduced. If the light irradiation angle is less than 1 degree, when detecting a foreign object M that is bent upward or downward, a part of the object M may be outside the light irradiation range, resulting in missed detection of the foreign object F.

[0024] 3b, as an example, the light source 210 of the light irradiation unit 200 may include a plurality of lower light sources 211 arranged symmetrically with respect to one another and a plurality of upper light sources 212 installed at a higher position than the lower light sources 211 and arranged symmetrically with respect to one another. The lower light sources 211 and the upper light sources 212 are alternately arranged along the light irradiation unit 200 and irradiate light at different angles, with the lower light sources 211 irradiating at a low angle of 1 to 30 degrees and the upper light sources 212 irradiating at a high angle of 31 to 60 degrees. By irradiating light at low and high angles using the lower light sources 211 and the upper light sources 212 arranged symmetrically with respect to one another in this manner, when a plurality of foreign objects F are adjacent to one another, a detection error in which scattered light from small foreign objects hidden by scattered light from larger foreign objects is not detected can be prevented, thereby increasing the reliability of detection.

[0025] In addition, the plurality of lower light sources 211 and the plurality of upper light sources 212 may be alternately and symmetrically arranged in the accommodation space of one light irradiation ring 220, or the light irradiation ring 220 may be divided into a lower light irradiation ring and an upper light irradiation ring above the lower light irradiation ring, and the plurality of lower light sources 211 may be symmetrically arranged in the lower light irradiation ring, and the upper light sources 212 may be symmetrically arranged in the upper light irradiation ring.

[0026] The optical foreign matter detection device 1 according to the present invention can be configured such that a stage (not shown) is additionally installed below the light irradiation unit 200, and the object M is placed on the stage to detect foreign matter F using the optical unit 300. However, it can also be used without a stage by simply moving the optical housing 100 and placing it on the part of the object M where foreign matter F is to be detected.

[0027] The optical unit 300 is built into the upper part of the optical housing 100, includes an image sensor, and captures an image of the object M to detect foreign matter F contained in the object M using light scattering of the foreign matter F caused by light irradiated from a plurality of light sources 210.

[0028] The image captured by the optical unit 300 shows light scattering that occurs when light irradiated from the multiple light sources 210 is reflected by foreign matter F. This increases the detection size that the image sensor of the optical unit 300 can accept, thereby increasing its detection power, allowing foreign matter F to be easily and quickly detected and confirmed, and also enabling detection of foreign matter F that is smaller than the size that the original optical unit 300 can detect. For example, an image is made up of many very small squares called pixels, and if the detectable pixel size of the image sensor of the optical unit 300 is 1 μm, the image sensor cannot detect foreign matter F that is smaller than 1 μm. However, by utilizing light scattering as described above, foreign matter F is scattered and amplified from its original size, making it possible to detect foreign matter F that is as small as about 1 / 5 the size that the original image sensor of the optical unit 300 can detect.

[0029] The user device 400 may be an electronic device such as a computer, laptop, smartphone, tablet PC, or PDA that receives, stores, plays, and analyzes images captured by the optical unit 300 and includes a display screen and a communication module, and may be connected to the optical unit 300 via wired or wireless communication. The user device 400 is installed with a dedicated program that can detect and analyze foreign matter F from images.

[0030] The user device 400 may include a standard particle amplification length value calculation unit 410, a foreign substance length value comparison standard storage unit 420, a foreign substance detection unit 430, a foreign substance amplification length value calculation unit 440, a foreign substance length value judgment unit 450, a foreign substance analysis unit 460, and a judgment unit 480.

[0031] Standard particles are commercially available in various sizes and colors. A large number of standard particles are prepared in advance by size, and the standard particles are placed on the surface of the object M. Then, using the optical foreign matter detection device 1 of the present invention, light is irradiated onto the object M with a predetermined amount of light from a plurality of light sources 210 to cause light scattering by the standard particles. After that, when the image captured by the optical unit 300 is received by the user device 400, the standard particle amplification length value calculation unit 410 measures and calculates the amplification length value of the standard particles that have been light-scattered according to the length value of each standard particle from the image.

[0032] According to the inventor's experimental results, there is a correlation in which the light scattering amplification ratio of a standard particle decreases as the actual standard particle length value increases. In this case, the amplification ratio is "standard particle amplification length value / standard particle length value." By inputting the standard particle length value on the x-axis and the amplification ratio on the y-axis into a dedicated program and connecting the points corresponding to the values input on the x-axis and y-axis with a trend line using the dedicated program, a curved graph with a steeply decreasing gradient pointing downward to the right is created, as shown in Figure 4a.

[0033] For example, when the standard particle length value is 0.4 μm, the light scattering amplification ratio of the standard particle may be 3.5 times; when the standard particle length value is 1 μm, the light scattering amplification ratio of the standard particle may be 3 times; when the standard particle length value is 10 μm, the light scattering amplification ratio of the standard particle may be 2.5 times; when the standard particle length value is 100 μm, the light scattering amplification ratio of the standard particle may be 2 times; and when the standard particle length value is 1000 μm, the light scattering amplification ratio of the standard particle may be 1.2 times.

[0034] Therefore, as an example, standard particles having circular cross sections with standard particle length values of 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, and 1000 μm are prepared, and light is irradiated onto the standard particles using the optical foreign matter detection device 1 of the present invention to capture light-scattered images of the standard particles. Then, the standard particle amplification length value calculation unit 410 can calculate the light-scattered amplification length values of the standard particles from the images. For example, when the standard particle length value is 0.4 μm, the light scattering amplification ratio of the standard particle detected from the image may be 3.5 times, and therefore the standard particle amplification length value may be 1.4 μm; when the standard particle length value is 1 μm, the light scattering amplification ratio of the standard particle detected from the image may be 3 times, and therefore the standard particle amplification length value may be 3 μm; when the standard particle length value is 10 μm, the light scattering amplification ratio of the standard particle detected from the image may be 2.5 times, and therefore the standard particle amplification length value may be 25 μm; when the standard particle length value is 100 μm, the light scattering amplification ratio of the standard particle detected from the image may be 2 times, and therefore the standard particle amplification length value may be 200 μm; and when the standard particle length value is 1000 μm, the light scattering amplification ratio of the standard particle detected from the image may be 1.2 times, and therefore the standard particle amplification length value may be 1200 μm.

[0035] The foreign particle length value comparison standard storage unit 420 creates a graph showing the correlation between the standard particle length value and the standard particle amplification length value calculated by the standard particle amplification length value calculation unit 410, and stores the graph as a comparison standard for the foreign particle length value.

[0036] For example, if the x-axis is the standard particle length value and the y-axis is the standard particle amplification length value, and each value is input into a dedicated program, and the program is used to connect the points corresponding to the values input on the x-axis and y-axis with a trend line, a curved graph with a steeply decreasing slope pointing upward to the right is created, as shown in Figure 4b. If the intervals between the x-axis values are narrowed and the standard particle amplification length values are calculated in advance for more standard particle length values to create a graph, the accuracy of the comparison standard will be further increased.

[0037] The foreign object detection unit 430 detects light-scattered foreign objects F from the image captured by the optical unit 300 and transmitted by the optical unit 300, using light scattering of the foreign objects F irradiated from the light source 210 by photometry, and one or more light-scattered foreign objects F may be detected in the image.

[0038] The foreign substance amplification length value calculation unit 440 calculates a foreign substance amplification length value obtained by light scattering and amplification of the foreign substance F detected by the foreign substance detection unit 430. The foreign substance amplification length value calculation unit 440 can calculate foreign substance amplification length values in two or more directions based on the light scattering shape of the foreign substance F, and in this case, foreign substance amplification length values of the major axis and the minor axis of the foreign substance F can be calculated.

[0039] The foreign particle length value determination unit 450 determines the standard particle length value corresponding to the standard particle amplified length value identical to the foreign particle amplified length value from the comparison standard of the foreign particle length value comparison standard storage unit 420 as the actual foreign particle length value. The foreign particle length value determination unit 450 can derive foreign particle length values in multiple directions of a foreign particle F. The more foreign particle length values in multiple directions derived from a single foreign particle F, the more accurate the size and shape of the foreign particle F. However, since microscopic foreign particles F have simple shapes rather than complex shapes, deriving foreign particle length values in several directions, along with the light scattering shape, makes it easy to determine the actual shape of the foreign particle. For example, the shape of a foreign particle F can be derived from the foreign particle length values of the major and minor axes of the foreign particle F.

[0040] The foreign matter analysis unit 460 analyzes the size and shape of the foreign matter F from one or more length values of the foreign matter determined by the foreign matter length value determination unit 450, and calculates the area of the foreign matter F. For example, if the length values of the foreign matter derived from multiple directions are almost identical, the shape of the foreign matter F can be analyzed as circular; if the length values of the foreign matter derived from multiple directions are different, the shape of the foreign matter F can be analyzed as other than circular; and if the length of the major axis is much longer than the minor axis, the shape of the foreign matter F can be analyzed as fibrous. Once the size and shape of the foreign matter F are analyzed in this manner, the area of the foreign matter F can also be easily calculated using a dedicated program.

[0041] The determination unit 480 determines whether the object M is contaminated or not based on the information analyzed by the foreign matter analysis unit 460. The determination of whether the object M is contaminated or not varies depending on the type of object M, the size, shape, spacing, etc. of the foreign matter F. For example, in the case of a fibrous foreign matter F, it may not have a significant effect on the contamination of the specific object M, and in such a case, it may be determined to be a normal product.

[0042] Hereinafter, a process of detecting foreign matter F using the optical foreign matter detection device 1 according to the present invention and analyzing the size, shape, etc. of the foreign matter F will be described with reference to an embodiment.

[0043] For example, it is assumed that when the standard particle length value is 0.4 μm, the light scattering amplification ratio of the standard particle is 3.5 times; when it is 1 μm, the light scattering amplification ratio of the standard particle is 3 times; when it is 10 μm, the light scattering amplification ratio of the standard particle is 2.5 times; when it is 100 μm, the light scattering amplification ratio of the standard particle is 2 times; when it is 300 μm, the light scattering amplification ratio of the standard particle is 1.6 times; when it is 500 μm, the light scattering amplification ratio of the standard particle is 1.5 times; and when it is 1000 μm, the light scattering amplification ratio of the standard particle is 1.2 times.

[0044] 5A, assuming that the detectable pixel size limit of the image sensor of optical unit 300 is 1 μm, if foreign substance amplification length value calculation unit 440 calculates foreign substance amplification length value l2 of light-scattered foreign substance F detected by foreign substance detection unit 430 as 1.4 μm, foreign substance length value determination unit 450 determines the foreign substance length value l1 as the foreign substance length value l1 by deriving a standard particle length value of 0.4 μm, which corresponds to the standard particle amplification length value of 1.4 μm identical to foreign substance amplification length value l2 of 1.4 μm, from foreign substance length value comparison standard storage unit 420. Furthermore, if foreign substance length value l1 is derived from foreign substance amplification length values l2 from multiple directions, all of them are the same, so it can be determined that the foreign substance F is circular. While conventional optical detection devices cannot detect foreign substances F smaller than 1 μm, which is the pixel limit of the image sensor, as described above, one embodiment of the present invention can detect foreign substances F smaller than the pixel limit of the image sensor.

[0045] Also, referring to Figure 5b, if the foreign substance amplification length value calculation unit 440 calculates the foreign substance amplification length value a2 of the major axis of the light-scattered foreign substance F detected by the foreign substance detection unit 430 to be 750 μm and the foreign substance amplification length value b2 of the minor axis to be 480 μm, the foreign substance length value determination unit 450 will derive a standard particle length value of 500 μm, which corresponds to the standard particle amplification length value of 750 μm, from the foreign substance length value comparison standard storage unit 420 and determine it as the foreign substance length value a1 of the major axis, and will derive a standard particle length value of 300 μm, which corresponds to the standard particle amplification length value of 480 μm, from the foreign substance length value comparison standard storage unit 420 and determine it as the foreign substance length value b1 of the minor axis, thereby analyzing the foreign substance as having an approximately oval shape.

[0046] Also, referring to FIG. 5c, when the foreign object amplification length value calculation unit 440 calculates the foreign object amplification length value a2 of the long axis of the optically scattered foreign object F detected by the foreign object detection unit 430 to be 750 μm and the foreign object amplification length value b2 of the short axis to be 200 μm, the foreign object length value determination unit 450 derives the standard particle length value of 500 μm, which corresponds to the standard particle amplification length value of 750 μm, from the foreign object length value comparison reference storage unit 420 and determines it as the foreign object length value a1 of the long axis. It derives the standard particle length value of 100 μm, which corresponds to the standard particle amplification length value of 200 μm, from the foreign object length value comparison reference storage unit 420 and determines it as the foreign object length value b1 of the short axis. Since the length of the long axis is much longer than that of the short axis in this way, it can be analyzed as being in a fibrous form.

[0047] As described above, in the above-described embodiment, the size, shape, etc. of the foreign object are derived through the foreign object length values of the long axis and the short axis. However, if the foreign object length values calculated from other directions than the long axis and the short axis are added and analyzed together, more accurate size, shape, etc. can be derived.

[0048] The user device 400 further includes a light-scattered standard particle RGB value extraction unit 471, a foreign object color comparison reference storage unit 472, a light-scattered foreign object RGB value extraction unit 473, and a foreign object color determination unit 474, and can confirm the actual color of the foreign object F from the light-scattered foreign object F.

[0049] The light-scattered standard particle RGB value extraction unit 471 extracts the light-scattered standard particle RGB value from an image in which standard particles are irradiated with a predetermined amount of light by a plurality of light sources 210 for standard particles of different colors in advance, scattered by the standard particles, and imaged by the optical unit 300. By repeatedly performing such operations many times for each color of the standard particles, the range of the light-scattered standard particle RGB values for each standard particle color is determined. For example, the range of the light-scattered standard particle RGB values for standard particle colors such as black, white, red, green, blue, yellow, etc. can be extracted. The light-scattered standard particle RGB value can be expressed as a range for each of the R, G, and B components. For example, when the standard particle color is red, the range of the light-scattered standard particle RGB value can be determined as R≧200, 50<G<150, 50<B<150.

[0050] RGB values are a method of expressing an image by mixing red (R), green (G), and blue (B). An image is made up of many very small squares called pixels, and each pixel is made up of a combination of red, green, and blue, which can each be expressed as a number with 256 levels of color from 0 to 255. For example, RGB (255, 0, 0) can be expressed as red, and RGB (255, 100, 0) can be expressed as red mixed with green. However, the light-scattered color of standard particles also has its own RGB value, not just the actual color of the standard particles, and these light-scattering standard particle RGB values are expressed differently depending on the actual color of the standard particles.

[0051] The foreign substance color comparison standard storage unit 472 matches the range of RGB values of the light scattering standard particles with the color of the standard particles and stores the result as a comparison standard for the foreign substance color.

[0052] The light-scattering foreign substance RGB value extraction unit 473 extracts light-scattering foreign substance RGB values from the light-scattered image of the foreign substance F detected by the foreign substance detection unit 430. At this time, if the size of light scattered by the foreign substance F in the image spans multiple pixels, multiple light-scattering foreign substance RGB values can be extracted for each pixel, and these multiple light-scattering foreign substance RGB values have similar ranges because they are all colors scattered by a single foreign substance F. For example, if the size of light scattered by a red foreign substance F spans multiple pixels, the multiple light-scattering foreign substance RGB values have similar ranges without significant differences from each other.

[0053] The foreign object color determination unit 474 searches for the range of the light scattering standard particle RGB values that include the light scattering foreign object RGB values. At this time, the R, G, and B components of the light scattering foreign object RGB values search for the range of the light scattering standard particle RGB values that are included in the ranges of the R, G, and B components of the light scattering standard particle RGB values. Then, the standard particle color that matches the searched range of the light scattering standard particle RGB values is derived from the comparison criteria of the foreign object color comparison criteria storage unit 472 and determined as the foreign object color. In this way, if the foreign object color is determined, it is possible to easily determine where the foreign object F originated from, and the additional inflow of the foreign object F can be blocked. For example, when the foreign object color is determined to be red, it can be determined that the corresponding foreign object F is conducted from the operator's clothes.

[0054] As an example, when the standard particle color is red, assuming that the standard particle RGB values are stored in the foreign object color comparison criteria storage unit 472 in the range of R≧200, 50<G<150, 50<B<150, referring to FIG. 5d, if the foreign object F that is light-scattered from the image captured by the optical unit 300 extends over four pixels, the light scattering foreign object RGB value extraction unit 473 of the user device 400 extracts the foreign object RGB values for each pixel. At this time, if the light scattering foreign object RGB value of the first pixel P1 is RGB(220, 120, 120), the light scattering foreign object RGB value of the second pixel P2 is RGB(210, 110, 90), the light scattering foreign object RGB value of the third pixel P3 is RGB(210, 90, 110), and the light scattering foreign object RGB value of the fourth pixel P4 is RGB(215, 120, 110), when the foreign object color determination unit 474 compares the light scattering foreign object RGB values of the four pixels with the range of the light scattering standard particle RGB values and matches red, the foreign object color is determined to be red.

[0055] Furthermore, a foreign matter type analyzer can be connected to the optical unit 300 to analyze the type of foreign matter F contained in the target object M. For example, if a Raman spectrophotometer, FT-IR (Fourier transform infrared spectroscopy), or the like is connected to the optical unit 300, the type of foreign matter F can be accurately analyzed. Since the analysis of foreign matter using such a foreign matter type analyzer is a well-known technique, a detailed description thereof will be omitted. [Industrial Applicability]

[0056] The optical foreign body detector using light scattering and image analysis of the present invention detects and analyzes foreign bodies by combining light scattering and image analysis, thereby being able to ascertain the actual size, shape, area, color, etc. of the foreign body and determine the path of entry of the foreign body, making it possible to control contamination in clean rooms. It also has a high processing speed for foreign body detection and image analysis, is able to detect foreign bodies smaller than the pixel limit of the image sensor, prevents foreign body detection errors, and is highly reliable. It can be placed on an object without a stage, is portable, and can be easily moved to an object for use, making it industrially applicable.

Claims

1. An optical foreign body detection device that uses light scattering and image analysis to detect and analyze foreign bodies contained in an object, an optical housing; a light irradiation unit connected to and installed at a lower part of the optical housing and having a plurality of light sources disposed thereon to irradiate light toward an object below, the light sources irradiating light with a predetermined amount of light so that light scattering can occur due to foreign matter; an optical unit built into an upper part of the optical housing to capture an image of the object by using light scattering of the foreign matter caused by the light irradiated from the light sources to detect foreign matter contained in the object; and a user device that receives, stores, reproduces, and analyzes the image generated by the optical unit, The user device calculates light-scattered standard particle amplification length values by irradiating light according to standard particle length values for a number of standard particles having a correlation in which the light-scattered amplification ratio of the standard particles decreases as the standard particle length value increases, creates a graph relating to the correlation between the standard particle length values and the standard particle amplification length values, and stores the graph as a comparison standard for the foreign particle length value, calculates light-scattered foreign particle amplification length values for foreign particles detected from an image captured by the optical unit, derives a standard particle length value corresponding to the same standard particle amplification length value as the foreign particle amplification length value from the comparison standard, and determines the foreign particle length value, and can determine the size, shape, and area of the foreign particle from the foreign particle length value and the color of the foreign particle from the light-scattered foreign particle. The user device includes a standard particle amplification length value calculation unit that calculates light-scattered standard particle amplification length values according to each standard particle length value from an image captured by an optical unit after light is irradiated at a predetermined light intensity from a plurality of light sources onto a number of standard particles having a correlation in which the light-scattered amplification ratio of the standard particles decreases as the standard particle length value increases, a foreign particle length value comparison standard storage unit that creates a graph relating to the correlation between the standard particle length value and the standard particle amplification length value and stores it as a comparison standard for foreign particle length values, a foreign particle detection unit that detects light-scattered foreign particles from an image captured by the optical unit, a foreign particle amplification length value calculation unit that calculates light-scattered foreign particle amplification length values of foreign particles detected by the foreign particle detection unit, a foreign particle length value determination unit that derives a standard particle length value corresponding to the standard particle amplification length value identical to the foreign particle amplification length value from the foreign particle length value comparison standard storage unit and determines it as a foreign particle length value, and a foreign particle detection unit that determines foreign particle length values from the foreign particle length value determined by the foreign particle length value determination unit. a foreign matter analysis unit for analyzing the size and shape of the foreign matter and calculating the area of the foreign matter; a determination unit for determining whether the object is contaminated based on the information analyzed by the foreign matter analysis unit; a light-scattering standard particle RGB value extraction unit for extracting light-scattering standard particle RGB values from an image captured by an optical unit in which light is irradiated by a plurality of light sources with a predetermined amount of light and scattered by the standard particles; a foreign matter color comparison standard storage unit for matching a range of the light-scattering standard particle RGB values with the color of the standard particle and storing the result as a comparison standard for the foreign matter color; a light-scattering foreign matter RGB value extraction unit for extracting light-scattering foreign matter RGB values from the light-scattered image of the foreign matter detected by the foreign matter detection unit; and a foreign matter color determination unit for searching a range of the light-scattering standard particle RGB values that includes the light-scattering foreign matter RGB values, deriving a standard particle color that matches the searched range of the light-scattering standard particle RGB value from the foreign matter color comparison standard storage unit, and determining the standard particle color as the foreign matter color. The foreign substance amplification length value calculation unit can calculate the foreign substance amplification length values of the major axis and the minor axis, respectively, and the foreign substance length value determination unit can derive the foreign substance length values of the major axis and the minor axis, respectively.

2. 2. The optical foreign substance detection device using light scattering and image analysis according to claim 1, wherein the light irradiation unit has a light source irradiating an object at an angle of 1 to 60 degrees.

3. The light source of the light irradiation unit includes a plurality of lower light sources arranged symmetrically with each other and a plurality of upper light sources arranged symmetrically with each other at positions higher than the lower light sources, 2. The optical foreign substance detection device using light scattering and image analysis according to claim 1, wherein the lower light source and the upper light source are alternately arranged along the periphery of the light irradiation unit and irradiate light at different angles, the lower light source having a light irradiation angle of 1 to 30 degrees and the upper light source having a light irradiation angle of 31 to 60 degrees.

4. 2. The optical foreign body detection device using light scattering and image analysis according to claim 1, wherein the optical housing has an optical unit built in an upper part, a light irradiation unit connected to a lower part, a light scattering section that becomes smaller in diameter toward the upper part and provides a darkroom between the optical unit and the light irradiation unit, and a handle is formed on the outside, where light scattering occurs due to foreign bodies when light is irradiated by the light irradiation unit.

5. 5. The optical foreign object detection device using light scattering and image analysis according to claim 4, wherein the light irradiation unit includes: a light irradiation ring connected to a lower portion of the light scattering portion so as to protrude outward and having a through hole formed inside thereof, the light source being installed along the inside of the light irradiation ring to irradiate light toward the object from a plurality of directions; and a contact ring formed under the light irradiation ring to be in close contact with the surface of the object.

6. 6. The optical foreign substance detection device using light scattering and image analysis according to claim 5, wherein the adhesion ring contains, by weight, 30 to 50% polyphenylene sulfide resin, 15 to 25% SBR, 10 to 20% polyurethane resin, 10 to 20% polymethyl methacrylate, 5 to 10% 2-mercaptoadenine, and 1 to 5% light absorber.

7. 2. The optical foreign matter detection device using light scattering and image analysis according to claim 1, further comprising a foreign matter type analyzer connected to the optical unit for determining the type of foreign matter contained in the target object.

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