JP2008180706A - Defect detection device for optically transparent film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a defect with high accuracy by preventing misrecognition of the air, entering between an optically transparent film and an auxiliary member for observation as a defect. <P>SOLUTION: This device is equipped with a film transport means for conveying the optically transparent film 1 which is an inspection object; an imaging part 5 for imaging the appearance of the optically transparent film; an auxiliary member 2 for observation, arranged on the back of the optically transparent film imaged by the imaging part; an operation part 6 for detecting a defect by analyzing an image acquired by the imaging part; and a film-adhering means for making the optically transparent film adhere to the surface of the auxiliary member for observation. The auxiliary member for observation has substantially the same light reflection characteristic as that of a member on which the optically transparent film is to be stuck as a final product. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a light transmissive film used for the purposes of antireflection, scattering prevention, heat ray prevention (blocking), heat insulation, antifouling, durability (protection), etc. in applications such as optical applications, architectural applications, and automotive applications The present invention relates to a device for detecting defects in (light-transmitting film), and more particularly to a defect detecting device for detecting defects in a light-transmitting film in which a coating layer having a small film thickness is formed on the surface. It is.

  Examples of the light transmissive film used in optical applications, architectural applications, vehicle-mounted applications, and the like include an antireflection film that is a light transmissive film in which a plurality of coating layers are formed. Such a light transmissive film can be applied as an antireflection filter to the surface of a display such as a plasma display or a liquid crystal display. The said coating layer for giving a wavelength transmission characteristic function can illustrate the thing whose thickness is 1 micrometer or less.

  In the light-transmitting film having this coating layer, defects (defects with nuclei) caused by foreign matter entering between the film and the coating layer can be detected by visual observation, but are subtle due to variations in the thickness of the coating layer. Defects (nuclear-free defects) that occur as parts with different colors from the surroundings are extremely difficult to detect visually, and about 90% of defects are missed by visual inspection.

  For this purpose, Patent Document 1 illuminates the light transmissive film located on the surface of the black guide roller so that the light reflected by the front and back surfaces of the coating layer formed on the light transmissive film interferes. It has been proposed to detect defects by imaging the interference pattern.

  In this case, the defect without core as well as the defect with nucleus can be detected, but the reflection changes depending on the surface state of the guide roller. It will be detected as a defect.

In addition, when the light-transmitting film that is OK in the above inspection is used for the display as the final product, the guide roller that functioned as an auxiliary member for observation at the time of the inspection and the light-transmitting film in the display actually Due to the difference in light reflection characteristics from a member to be attached (generally black glass), there are many cases where defects actually exist.
JP 2006-208196 A

  This invention is invented in view of said conventional problem, Comprising: It aims at providing the defect detection apparatus of the light transmissive film which can perform a defect detection with high precision.

  In order to solve the above problems, a defect detection apparatus for a light transmissive film according to the present invention includes a film transport unit that transports a light transmissive film to be inspected, an imaging unit that captures an appearance of the light transmissive film, An auxiliary member for observation arranged behind the light transmissive film imaged by the imaging unit, and a calculation unit for analyzing the image obtained by the imaging unit to detect a defect, and A film adhesion means for bringing the film into close contact with the surface of the auxiliary member for observation is provided, and the auxiliary member for observation has almost the same light reflection characteristics as the member to which the light transmissive film is attached in the final product. And

  As the film contact means, a liquid filling means in which a liquid that does not erode the film is interposed between the light transmissive film and the observation auxiliary member can be suitably used.

  It is advantageous that the imaging unit is a line camera in that the size of the observation auxiliary member can be reduced and the inspection space can be reduced.

  In the present invention, since the auxiliary member for observation is arranged on the back surface, it is easier to find defects than when the light transmissive film is viewed alone, and between the light transmissive film and the auxiliary member for observation. Defects when air enters and is not recognized as a defect, and when the light-transmitting film is on the auxiliary member for observation and when the light-transmitting film is on the member to be attached in the final product Since the output level of the product is almost the same, it is easy to set the judgment level when judging that it is a defect. You will never be invited.

  Hereinafter, the present invention will be described with reference to an embodiment shown in the accompanying drawings. In FIG. 1, reference numeral 1 denotes a light-transmitting film as an antireflection film having a multilayer coating on the surface. The light transmissive film 1 is fed to the take-up drum 12 side by unwinding by driving the motor 11.

  In the figure, reference numeral 2 denotes a roller-shaped auxiliary member for observation, which is disposed by immersing the lower part in a water tank 20 to which pure water is supplied. The light-transmitting film 1 is composed of the roller-shaped auxiliary member for observation 2. Sent while touching the surface. Instead of the pure water, a volatile solvent such as methyl ethyl ketone or an oil-based liquid such as essential oil may be used.

  An illumination unit 4 that is a three-wavelength fluorescent lamp is disposed above the observation auxiliary member 2 to illuminate the surface of the portion of the light transmissive film 1 that is in contact with the observation auxiliary member 2. Further, the imaging unit 5 includes a line camera that captures a portion illuminated by the illumination unit 4, and the imaging unit 5 is included in the calculation unit 6 that detects a defect obtained by analyzing the image obtained by the imaging unit 5. It is connected.

  In the figure, 61 is a draining doctor for removing water adhering to the light transmissive film 1, and 62 is an air blower.

  In detecting the defect of the light transmissive film 1, the roller-shaped auxiliary observation member 2 is rotated to wet the surface of the auxiliary observation member 2 with pure water and the light transmissive film 1 in a tensioned state. Is brought into contact with the observation auxiliary member 2. At this time, the pure water prevents the air layer from being generated between the light transmissive film 1 and the observation auxiliary member 2, and the back surface of the light transmissive film 1 is brought into close contact with the surface of the observation auxiliary member 2. .

  Further, the observation auxiliary member 2 used here has a surface having light reflection characteristics substantially the same as the light reflection characteristics of a member to be attached on a product in which the light transmissive film 1 is finally used. It has become. Most preferably, the observation auxiliary member 2 is made of the same material as the above member, but may be made of other materials as long as the light reflection characteristics are substantially the same. Even if the member is a glass member as described above and the observation auxiliary member 2 is aluminum or iron, it is only necessary that the surface treatment can provide substantially the same light reflection characteristics. When water is used as the film adhesion means, the surface thereof is preferably hydrophilic.

  In this case, since the light transmissive film 1 is in close contact with the observation auxiliary member 2, the air between the light transmissive film 1 and the observation auxiliary member 2 leads to an erroneous result in detecting a defect. There is no end. Further, the defect without the nucleus may be invisible if the type of the light source is changed. However, the light reflection characteristic of the surface of the auxiliary member for observation 2 is a member to which the light transmissive film is attached in the final product. Since the light reflection characteristics are substantially the same, there are defects when the light transmissive film 1 is on the observation auxiliary member 2 and when the light transmissive film is on the member to be attached in the final product. Therefore, it is easy to set the judgment level when judging that it is defective, and it is recognized that there is no defect when actually used. It does not cause such a situation.

  FIG. 2 shows another example. Here, a flat plate-like member is used as the observation auxiliary member 2, and at the same time, water injection means 71 for injecting pure water between the light transmissive film 1 and the observation auxiliary member 2 as a film adhesion means, and light transmission property. And a roller 72 for pressing the film 1 against the observation auxiliary member 2. In the figure, 73 is a water tray. The auxiliary member for observation 2 may be pressed against the light transmissive film 1 to be in close contact therewith.

  In this case, since the observation auxiliary member 2 is a flat plate, it is easy to use the member itself to which the light transmissive film is attached in the final product.

It is a block diagram of an example of an embodiment of the invention. It is a block diagram of the other example same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light transmissive film 2 Auxiliary member for observation 5 Imaging part 6 Calculation part

Claims (3)

  Film transporting means for transporting the light transmissive film to be inspected, an image pickup section for picking up the appearance of the light transmissive film, and an observation auxiliary member disposed behind the light transmissive film picked up by the image pickup section And an arithmetic unit for analyzing the image obtained by the imaging unit to detect defects, and a film contact means for bringing the light transmissive film into close contact with the surface of the auxiliary member for observation. A member for detecting a defect in a light transmissive film, characterized in that the member has substantially the same light reflection characteristics as a member to which the light transmissive film is pasted in the final product.   2. The defect detecting device for a light transmissive film according to claim 1, wherein the film contact means is a liquid filling means for interposing a liquid that does not erode the film between the light transmissive film and the observation auxiliary member.   The defect detection apparatus for a light transmissive film according to claim 1, wherein the imaging unit is a line camera.

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