Apparatus and method for detecting defect of optical film
阅读说明：本技术 用于检测光学膜的缺陷的装置和方法 (Apparatus and method for detecting defect of optical film ) 是由 金浩振 杨命坤 崔恒硕 张应镇 于 2018-07-27 设计创作，主要内容包括：本发明提供了能够容易地检测光学膜中/上存在的缺陷的用于检测光学膜的缺陷的装置和方法。光学膜缺陷检测装置包括：用于照射光的光照射单元；用于通过反射由所述光照射单元照射的光而将光引导至光学膜的反射单元；用于显示投射形状的屏幕,所述投射形状是当将光投射到所述光学膜上时所述光学膜中的缺陷的投射；和用于采集显示在所述屏幕上的投射形状的图像的成像单元。(The present invention provides an apparatus and method for detecting defects of an optical film, which can easily detect defects existing in/on the optical film. The optical film defect detecting apparatus includes: a light irradiation unit for irradiating light; a reflection unit for guiding the light to the optical film by reflecting the light irradiated by the light irradiation unit; a screen for displaying a projected shape, the projected shape being a projection of a defect in the optical film when light is projected onto the optical film; and an imaging unit for acquiring an image of the projected shape displayed on the screen.)
1, an apparatus for detecting defects in an optical film, the apparatus comprising:
a light emitting unit that emits light;
a reflection unit reflecting the light emitted by the light emitting unit and guiding the light to the optical film;
a screen displaying a projected shape obtained by projecting light on the optical film to detect a defect of the optical film; and
an image capturing unit that captures an image of the projected shape displayed on the screen.
2. The apparatus of claim 1, wherein the screen forms an th angle θ with a direction in which the image of the screen is acquired by the image acquisition unit1Equal to a second angle θ formed between the optical film and light projected on the optical film2。
3. The device of claim 2, wherein the th and second angles are 25 ° or more and 48 ° or less.
4. The device of claim 1, wherein a distance between the screen and an area of the optical film on which light is projected is 90mm or more and 130mm or less.
5. The device according to claim 1, wherein a distance between a point of emitted light on the light emitting unit and a point of reflected light on the reflecting unit is 165mm or more and 185mm or less.
6. The device of claim 1, wherein a distance between a point of reflected light on the reflection unit and a region of the optical film to which light reflected by the reflection unit is directed is 580mm or more and 650mm or less.
7. The apparatus of claim 1, further comprising:
an analysis unit detecting a defect of the optical film by analyzing an image of the screen captured by the image capture unit to display the projected shape.
A method of detecting defects in an optical film of the species , the method comprising:
emitting light to the reflection unit;
projecting the light reflected by the reflection unit on the optical film;
obtaining an image by acquiring an image of a screen displaying a projected shape obtained by projecting light on the optical film to detect a defect of the optical film; and
detecting a defect of the optical film by analyzing the image.
9. The method of claim 8, further comprising:
the optical film is supplied by using a roll-to-roll method.
Technical Field
This application claims priority and benefit to korean patent application No. 10-2017-.
The present invention relates to an apparatus and method for detecting defects of an optical film.
Background
The optical film having optical characteristics is used to manufacture display cells including Liquid Crystal Displays (LCDs), Organic Light Emitting Diodes (OLEDs), Plasma Display Panels (PDPs), electrophoretic displays (EPDs), and the like. In general, an optical film has a structure in which a polarizing film having optical characteristics and a protective film for protecting the polarizing film are stacked on each other.
During the process of manufacturing and transporting the optical film, defects having various shapes may occur in/on the optical film in some cases, for example, when foreign substances are introduced into the optical film, the optical film is pressed, the surface of the optical film is scratched or the optical film is wrinkled. The above-described defects may cause defects of a display unit manufactured by using the optical film.
Accordingly, there is a need for a technique capable of detecting defects having various shapes present in/on an optical film.
Korean patent No. 10-1082699 (hereinafter, referred to as patent document 1) proposes a device for detecting defects of an optical film by collecting an image of the optical film. Patent document 1 discloses testing an optical film by passing light emitted by a light source through the optical film so that an image of the optical film is collected by an image pickup device installed at a position facing the light source.
[ related art documents ]
[ patent document ]
Patent document 1: korean patent No. 10-1082699
Disclosure of Invention
Technical problem
The present specification is directed to providing an apparatus and method for detecting defects of an optical film.
Technical scheme
exemplary embodiments of the present invention provide an apparatus for detecting a defect of an optical film, the apparatus including a light emitting unit that emits light, a reflection unit that reflects the light emitted by the light emitting unit and guides the light to the optical film, a screen that displays a projected shape obtained by projecting the light on the optical film to detect the defect of the optical film, and an image collecting unit that collects an image of the projected shape displayed on the screen.
Another exemplary embodiments of the present invention provide a method of detecting a defect of an optical film, the method including emitting light toward a reflection unit, projecting the light reflected by the reflection unit on the optical film, obtaining an image by collecting an image of a screen displaying a projected shape obtained by projecting the light on the optical film to detect the defect of the optical film, and detecting the defect of the optical film by analyzing the image.
Advantageous effects
According to exemplary embodiments of the present invention, defects having various shapes (e.g., shapes of pressing, scratching, folding, and wrinkling) in/on an optical film may be easily detected.
According to the exemplary embodiments of the present invention, since the light irradiation width of the light emitted by the light emitting unit is expanded by the reflecting unit, the region where the defect of the optical film can be detected may be widened.
According to the exemplary embodiments of the present invention, defects existing in/on an optical film may be easily detected.
Drawings
Fig. 1 is a diagram schematically showing the configuration of an apparatus for detecting defects of an optical film according to exemplary embodiments of the present invention.
Fig. 2 is a diagram schematically illustrating a state in which light emitted by a light emitting unit is guided to an optical film through a reflecting unit according to an exemplary embodiment of the present invention.
Fig. 3 is a diagram schematically illustrating the configuration of an apparatus for detecting defects of an optical film including an analysis unit according to an exemplary embodiment of the present invention.
Fig. 4a is a diagram schematically showing a state where interference is generated between light reflected by the reflection unit and the transfer unit when the th angle and the second angle are less than 25 °, and fig. 4b is a diagram schematically showing a state where light interferes with the transfer unit when the image pickup unit picks up an image of a screen when the th angle and the second angle are greater than 48 °.
Fig. 5 is a diagram illustrating images of the optical films obtained according to example 1, comparative example 1, and comparative example 2.
Detailed Description
Throughout this specification, when members are disposed "on" another member, this includes not only the case where members are in contact with another member, but also the case where members are present between two members.
Hereinafter, the present specification will be described in more detail.
exemplary embodiments of the present invention provide an apparatus for detecting a defect of an optical film, the apparatus including a light emitting unit that emits light, a reflection unit that reflects the light emitted by the light emitting unit and guides the light to the optical film, a screen that displays a projected shape obtained by projecting the light on the optical film to detect the defect of the optical film, and an image collecting unit that collects an image of the projected shape displayed on the screen.
According to exemplary embodiments of the present invention, defects having various shapes (e.g., shapes of pressing, scratching, folding, and wrinkling) in/on an optical film may be easily detected.
The optical film includes a polarizing film, and may include films having optical characteristics such as a phase difference film, a vision compensation film, and a brightness improvement film in addition to the polarizing film.
Fig. 1 is a diagram schematically illustrating a configuration of an apparatus for detecting defects of an optical film according to exemplary embodiments of the present invention, and in particular, fig. 1 is a diagram illustrating an apparatus for detecting defects of an optical film, which includes a
According to an exemplary embodiment of the present invention, an apparatus for detecting a defect of an optical film may include a transfer unit that may transfer the optical film in a predetermined direction. The transfer unit may include various transfer devices that can transfer the optical film. Specifically, the conveying unit includes a conveying roller, and the optical film may be conveyed by using the conveying roller.
According to exemplary embodiments of the present invention, the transfer roll may have a diameter of 100mm to 125mm, or 110mm to 120 mm. In particular, the diameter of the transfer roller may be 118 mm. Further, referring to fig. 1, the shortest distance between the centers of the two
Since the shortest distance between the diameter of the transfer roller and the center of the transfer roller is adjusted to the above range, the operation efficiency of the apparatus for detecting defects of the optical film can be improved, and the case where the transfer roller interferes with the light reflected by the reflection unit and the case where the transfer roller interferes with the image pickup unit when the image pickup unit picks up the image of the screen can be effectively prevented.
According to an exemplary embodiment of the present invention, the transfer roller may transfer the optical film in an in-line (in-line) manner in which the optical film travels in a single direction. Accordingly, the optical film may be continuously transferred along the transfer roller while being wound on the transfer roller, and the light emitted by the light emitting unit may be reflected by the reflecting unit and guided to the transferred optical film. That is, according to the exemplary embodiment of the present invention, a roll of an optical film extending in a longitudinal direction thereof may be supplied to an apparatus for detecting a defect of the optical film by using a roll-to-roll method, so that the defect of the optical film may be detected.
According to an exemplary embodiment of the present invention, in the case where whether or not there is a defect in/on the optical film extending in the longitudinal direction thereof is checked by the apparatus for detecting a defect of the optical film, the transfer unit may transfer the optical film in the longitudinal direction of the optical film. Referring to fig. 1, the
According to an exemplary embodiment of the present invention, a known device may be used as the light emitting unit, and there is no limitation as long as the device emits light. In particular, the light emitting unit may include a Light Emitting Diode (LED) in consideration of a lifetime, luminance stability, and maintainability of the light emitting unit. Further, the light emitting unit may include a plurality of LEDs, and may include a light emitting device such as a fluorescent lamp or an incandescent lamp in addition to the LEDs.
According to an exemplary embodiment of the present invention, the reflection unit may include a device capable of changing a path of light emitted by the light emitting unit. In particular, the reflection unit may include a plane mirror. Since the reflection unit includes the plane mirror, the reflection angle of the light emitted by the light emitting unit with respect to the reflection unit can be easily adjusted, and thus the light can be efficiently guided to the optical film.
Fig. 2 is a diagram schematically illustrating a state in which light emitted by a light emitting unit is guided to an optical film through a reflecting unit according to an exemplary embodiment of the present invention. Specifically, referring to fig. 2, light emitted by the
According to an exemplary embodiment of the present invention, the reflection unit may guide light to the optical film while expanding a light irradiation width of the light. When the light emitted by the light emitting unit is reflected by the reflecting unit, the light irradiation width of the light can be expanded while changing the path of the light to directly face the optical film. That is, according to the exemplary embodiments of the present invention, since the light irradiation width of the light emitted by the light emitting unit is expanded by the reflection unit, the region where the defect of the optical film can be detected may be widened.
Referring to fig. 2, the light irradiation width d4 of the light emitted by the
According to an exemplary embodiment of the present invention, the reflection unit may guide the light emitted by the light emitting unit to the optical film such that a light irradiation width is 900mm or more. Referring to fig. 2, the reflection unit may guide light to the optical film such that the light irradiation width d4 is 900mm to 3,000mm, 900mm to 2,500mm, 900mm to 1,500mm, 1,500mm to 3,000mm, or 1,700mm to 2,500 mm.
Since the light irradiation width of the light reflected by the reflection unit is adjusted to the above range, the light can be efficiently guided in the entire width direction of the optical film, and the uniformity of the light amount can be prevented from being deteriorated.
According to an exemplary embodiment of the present invention, a light irradiation width of light guided to an optical film may be controlled by adjusting a distance between a light emitting unit and a reflecting unit. Specifically, the light irradiation width of the light guided to the optical film may be expanded by reducing the distance between the light emitting unit and the reflecting unit. Further, the light irradiation width of the light guided to the optical film may be reduced by increasing the distance between the light emitting unit and the reflecting unit.
According to an exemplary embodiment of the present invention, light guided to the optical film by the reflection unit is projected on the optical film, and a projected shape formed by projecting light on the optical film such that a defect existing in/on the optical film is projected may be displayed on a screen.
According to an exemplary embodiment of the present invention, a screen for projecting light may be used as the screen. In particular, a polypropylene sheet may be used for the screen. Further, the surface of the screen may be processed to be white so that a projected shape formed by defects existing in/on the projection optical film may be clearly displayed on the screen. Further, in order to minimize distortion (distortion) of a projection shape displayed on a screen, a surface of the screen is processed to reduce surface roughness of the screen. In addition, the screen may have light diffusion and transmission characteristics.
Meanwhile, defects existing in/on the optical film may have various shapes (e.g., shapes of pressing, scratching, folding, or wrinkling of the optical film caused by external force). In more detail, the defect existing in/on the optical film may mean a pressed shape of the optical film caused by introduction of foreign substances, a pressed shape formed when the optical film is wound on a transfer roll, a pressed shape formed when the thickness of an adhesive or an adhesive applied to the optical film is deformed, or a defect causing distortion of a front shape or a rear shape of the optical film or a change in the shape of the optical film by a wrinkle formed when the optical film is folded.
According to an exemplary embodiment of the present invention, the type and size of defects present in/on the optical film may be determined by analyzing the projected shape displayed on the screen. Specifically, when the optical film is pressed and thus has a convex shape (for example, in the form of a magnifying glass), the luminance of the projected shape displayed on the screen is higher than that of the projected shape of the optical film having no defects, and thus the projected shape in the form of white dots can be displayed on the screen.
Further, in the case where foreign substances are introduced into the optical film, the light guided by the reflection unit cannot pass through the optical film, and thus the luminance of the projection shape displayed on the screen is lower than that of the projection shape of the optical film having no defects, so that the projection shape in the form of a black dot can be displayed on the screen. Further, in the case where the optical film is folded or scratched, the projected shape displayed on the screen may be displayed in the form of a line including white or black dots continuously connected and extended.
Therefore, according to the exemplary embodiments of the present invention, it is possible to determine the type and size of a defect existing in/on the optical film by analyzing the projected shape displayed on the screen, and thus it is possible to determine whether the optical film has a defect.
According to an exemplary embodiment of the present invention, the image pickup unit may be disposed to be spaced apart from the screen, and the image of the projection shape displayed on the screen may be obtained by picking up the image of the projection shape. The method of obtaining an image may be performed by: an image of a projection shape displayed on a screen due to a defect of an optical film is captured by using a camera included in an image capturing unit, and the image is converted into image data. A CCD sensor or a scanning camera may be used as the camera included in the image pickup unit, but the type of the camera is not limited. Further, in order to minimize distortion of the captured image of the projected shape displayed on the screen, the focus of the image capturing unit may be set to be formed at the center of the screen.
In accordance with an exemplary embodiment of the present invention, the number of image capturing units may be more than . thus, an apparatus for detecting defects of an optical film may include a single light emitting unit and a plurality of image capturing units, the plurality of image capturing units may respectively capture images of image capturing regions that may be defined on a screen.
Fig. 3 is a diagram schematically illustrating the configuration of an apparatus for detecting defects of an optical film including an analysis unit according to an exemplary embodiment of the present invention, and in particular, fig. 3 is a diagram illustrating an apparatus for detecting defects of an optical film having an
According to an exemplary embodiment of the present invention, the apparatus for detecting a defect of an optical film may further include an analysis unit detecting a defect of an optical film by analyzing an image of the screen, which is captured by the image capture unit to display the projected shape. The analysis unit uses the image data obtained by the image acquisition unit as input data, and can perform image processing by using a numerical value regarding the brightness of an image in the input image data. The following analysis process may be performed on the data that has undergone image processing: the defect is detected by comparing the brightness value of the projected shape with the brightness value of the projected shape of the optical film having no defect to determine whether the projected shape of the optical film has a black or white spot. Further, the analysis unit may analyze the defect by measuring a size of a portion having a black or white dot.
The analysis unit may comprise an electronic device in which an analysis program capable of image processing and comparative analysis is embedded. Specifically, a computer, a tablet PC, a personal cellular phone, a wearable device, a Programmable Logic Controller (PLC), or the like may be used as the analysis unit.
According to an exemplary embodiment of the present invention, an th angle θ formed between the screen and a direction in which the image of the screen is captured by the image capturing unit1May be equal to a second angle theta formed between the optical film and light projected on the optical film2。
Referring to fig. 1, the position of the
According to the exemplary embodiment of the present invention, since the th angle and the second angle are set to be equal to each other, distortion of the projected shape displayed on the screen is minimized, so that an error generated when analyzing the captured image of the projected shape may be reduced and defects existing in/on the optical film may be more accurately detected.
According to an exemplary embodiment of the present invention, the th and second angles may be 25 ° or more and 48 ° or less, specifically, the th and second angles may be 30 ° or more and 40 ° or less, 35 ° or more and 40 ° or less, or 30 ° or more and 45 ° or less, more specifically, the th and second angles may be 35 °.
In addition, in the case where the th angle and the second angle are equal to each other and the th angle and the second angle are within the above-described ranges, it is possible to more accurately detect defects present in/on the optical film by suppressing a decrease in an average peak luminance value of defects of the optical film detected by the image pickup unit.
In the present invention, the brightness value refers to the degree of brightness of an image obtained by the image pickup unit, and can be set to 0 level to 255 levels by classification based on gray levels. In this case, the 0 level means a case where the luminance of the image corresponds to black, and the 255 level means a case where the luminance of the image corresponds to white. Further, the average peak luminance value of the defect of the optical film may mean an average value of differences in luminance values (gray levels) between a region where the defect is not detected and a region where the defect is detected in the obtained image.
In the case where the th angle and the second angle are less than 25 °, distortion of the projection shape displayed on the screen may increase and an angle formed between the screen and a direction in which the image of the screen is captured by the image capturing unit decreases, and thus there may be a problem in that the projection shape is omitted from the image captured by the image capturing unit and thus an erroneous image is obtained.
FIG. 4a is a view schematically showing a state where light reflected by the reflection unit and the transmission unit interfere with each other when the th angle and the second angle are less than 25When the th angle theta1And a second angle theta2A diagram of a state where light reflected by the
In the case where the th angle and the second angle are greater than 48 °, there may be a problem in that uniformity of the amount of light is reduced because the light guided by the reflection unit undergoes interfacial reflection or irregular reflection on the optical film, and further, in the case where the th angle and the second angle are greater than 48 °, the light interferes with the transfer unit when the image of the screen is captured by the image capturing unit, and thus there may be a problem in that an erroneous image is obtained.
FIG. 4b is a view schematically showing a state where light interferes with the transfer unit when the image pickup unit picks up an image of the screen when the th angle and the second angle are greater than 48 deg. particularly, FIG. 4b is a view showing a state where the th angle theta is greater than 48 deg1And a second angle theta2The
According to an exemplary embodiment of the present invention, a distance between the screen and a region of the optical film on which light is projected may be 90mm or more and 130mm or less, particularly, a distance between the screen and a region of the optical film on which light is projected may be 100mm or more and 120mm or less, or 105mm or more and 115mm or less, more particularly, a distance between the screen and a region of the optical film on which light is projected may be 90 mm.
Referring to fig. 1, since the distance d1 between the
According to an exemplary embodiment of the present invention, a distance between a point of emitting light on the light emitting unit and a point of reflecting light on the reflecting unit may be 165mm or more and 185mm or less. Specifically, the distance between the point of the light emitted on the light emitting unit and the point of the light reflected on the reflecting unit may be 170mm or more and 180mm or less. More specifically, the distance between the point of the emitted light on the light emitting unit and the point of the reflected light on the reflecting unit may be 175 mm.
Referring to fig. 1, the distance d3 between the point of emitted light on the
According to an exemplary embodiment of the present invention, a distance between a point of reflected light on the reflection unit and a region of the optical film to which the light reflected by the reflection unit is directed may be 580mm or more and 650mm or less, specifically, a distance between a point of reflected light on the reflection unit and a region of the optical film to which the light reflected by the reflection unit is directed may be 590mm or more and 630mm or less, 600mm or more and 610mm or less, 590mm or more and 610mm or less, or 620mm or more and 650mm or less, more specifically, a distance between a point of reflected light on the reflection unit and a region of the optical film to which the light reflected by the reflection unit is directed may be 650 mm.
According to an exemplary embodiment of the present invention, an apparatus for detecting defects of an optical film may be disposed in a dark room such that distortion of a projected shape displayed on a screen is minimized, and the projected shape may be more clearly displayed on the screen.
Meanwhile, the distance between the image pickup unit and the screen may be changed based on the resolution of the camera included in the image pickup unit.
Another exemplary embodiments of the present invention provide a method of detecting a defect of an optical film, the method including emitting light toward a reflection unit, projecting the light reflected by the reflection unit on the optical film, obtaining an image by collecting an image of a screen displaying a projected shape obtained by projecting the light on the optical film to detect the defect of the optical film, and detecting the defect of the optical film by analyzing the image.
According to the exemplary embodiments of the present invention, defects existing in/on an optical film may be easily detected.
The light emitting unit, the reflecting unit, the screen, the image pickup unit, and the like used in the method for detecting a defect of an optical film according to the exemplary embodiment of the present invention may be the same as those included in the apparatus for detecting a defect of an optical film according to the exemplary embodiment of the present invention.
According to an exemplary embodiment of the present invention, light may be emitted to the reflection unit by using the light emitting unit. When light is emitted to the reflection unit, the light is reflected by the reflection unit and guided to the optical film, and the light guided to the optical film is projected on the optical film and reaches the screen. When light is projected on the optical film, a projected shape formed by projecting a defect existing in/on the optical film may be displayed on the screen. The image may be obtained by capturing an image of the projection shape displayed on the screen using an image capturing unit. The defect of the optical film may be detected by analyzing the obtained image using an analyzing unit.
According to an exemplary embodiment of the present invention, the method of detecting a defect of an optical film may further include supplying the optical film by using a roll-to-roll method. Specifically, a roller of the optical film extending in the longitudinal direction thereof is supplied in the longitudinal direction thereof by using a roller-to-roller method, and a defect of the optical film can be detected. Therefore, according to the exemplary embodiments of the present invention, since the optical film is supplied by using the roll-to-roll method, the speed of the process of detecting the defect of the optical film may be improved, and the defect detecting process may be continuously performed.
[ description of reference numerals ]
100: light emitting unit
200: reflection unit
300: screen
400: image acquisition unit
500: transfer unit
600: analysis unit
EMBODIMENTS FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to examples for specifically describing the present invention. However, the embodiment according to the present invention may be modified in various forms, and the scope of the present invention is not construed as being limited to the embodiment to be described in detail below. The embodiments of the present description are provided to more fully explain the present invention to those of ordinary skill in the art.
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