KR20060125483A - A method for producing optical laminate film - Google Patents

Abstract

A method for producing a laminated optical film is provided to enhance optical property of an LCD(Liquid Crystal Display) panel by maintaining an SN(Signal to Noise) ratio of a luminance signal from a defective portion of the laminated optical film. A polarization film is coupled with a phase difference film(11) to form a laminated optical film. The phase difference film of a constant width is transferred in the longitudinal direction and a pair of polarizers are arranged in parallel to both sides of the phase difference film. An optical compensation film(24) of a birefringence property is arranged between the polarizer and the phase difference film. Lights from first and second polarizers are received to detect a defect from a luminance signal. Then the phase difference film is coupled with the polarization film and the defective portion is removed from the phase difference film.

Description

The manufacturing method of laminated optical film {A method for producing optical laminate film}

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which shows schematic structure of the defect detection and defect marking apparatus 10 of the film in this invention.

2 is a simplified cross-sectional view showing the configuration of the defect detection means 25 for the retardation film in the defect detection and defect marking apparatus of FIG. 1.

3 is a view showing a thinking manner of the marking in the defect marking apparatus of FIG.

FIG. 4 is a diagram showing an example of a thinking manner of control when the control means 20 of FIG. 1 operates the marking means 14 and performs marking.

Explanation of the sign

10 Fault detection marking device

11 phase difference film

11a conveying direction

12 imaging means

13, 13b, 13c defect

14 Marking means

15 marks

17 lighting devices

18 conveying speed detection device

19 Image Processing Unit

20 control means

21,... , camera

22, 23 polarizer

24 optical compensation film

25 Fault detection means

31,... , Marker

40 blocks

41, 42, 43, 44 sides

[Patent Document 1] Japanese Unexamined Patent Publication No. 2005-49158

[Patent Document 2] Japanese Unexamined Patent Publication No. 2001-305070

This invention relates to the manufacturing method of the laminated optical film formed by laminating | stacking a polarizing film and retardation film.

Conventionally, in manufacturing processes, such as a synthetic resin film and paper, various processes are performed automatically in the state of the constant width | variety and the elongate strip | belt shape, and are cut so that finally it may become a predetermined shape according to a product use. The detection of the defective part which does not satisfy a product use is also performed automatically in a strip | belt-shaped state, and a mark is performed so that identification of the defective part may be easy in a post process.

When manufacturing the polarizing film used for a liquid crystal display panel, in processes, such as manufacture as a synthetic resin film and provision of the polarization characteristic by extending | stretching to a fixed direction, a film is continuously performed in the state of a magnificent strip shape, Cut into a predetermined size or direction depending on the intended use of the product. When inspecting a defect automatically, detection of a defect and marking about a defect are performed along the conveyance path of a film. In the same manner as for the retardation film, the film is continuously carried out in the state of the elongated band shape, and the detection of the defect and the marking for the defect are performed along the conveyance path of the film.

The polarizing film and retardation film obtained in this way are bonded so that it may become a predetermined axial angle, they are cut | disconnected by the chip of a predetermined size normally, the chip | tip which has a defect part based on a mark is removed, and it becomes a product of a laminated optical film.

As a defect inspection method, such as a foreign material of a synthetic resin film, it transmits to a synthetic resin film from a light source, photographs the transmitted light or reflected light with a camera, or arranges a synthetic resin film between two polarizing plates arrange | positioned cross nicol, The method of image | photographing the transmitted light from the camera, image-processing the imaging, and defect inspection is known (patent document 1).

Moreover, as a marking method of a film defect, the range prescribed | prescribed by the both sides of the width direction about the method of performing a linear mark on the side edge of the film of the part containing a defect, the method of directly marking a defect position, and a defect part The method of marking on the position used in the vicinity of is known (patent document 2).

However, in the defect detection method described in JP 2005-49158 A, when the synthetic resin film is a retardation film, even if the SN ratio of the luminance signal of the defective portion is low, the defect detection accuracy is low, and the marking is surely performed, A defect appears when the laminated optical film formed by bonding with a polarizing film is used for a liquid crystal display panel.

An object of the present invention is to provide a laminated optical film formed by bonding a polarizing film and a retardation film with few defects.

This invention WHEREIN: The method of bonding a polarizing film and retardation film and manufacturing a laminated optical film WHEREIN: The retardation film which has a fixed width | variety is conveyed in the longitudinal direction perpendicular | vertical to the width direction, At that time, to both sides of the retardation film A pair of polarizers are arranged in a cross nicol parallel to the film surface, and an optical compensation film having birefringence characteristics is disposed between the polarizer and the retardation film, and the light is projected from the outside of one polarizer, from the other polarizer. It is a manufacturing method of the laminated optical film characterized by receiving a transmitted light, detecting a defect from the brightness signal, and then bonding it with a polarizing film, and removing a defect part.

A polarizing film is a film having a function of transmitting only light in a specific vibration direction, and is produced by dyeing and stretching a polyvinyl alcohol film with iodine or the like, and sold by Sumikaran (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd.) or the like. It is becoming.

The retardation film is a film having a function of compensating for retardation, removing coloring to improve visibility, or expanding the viewing angle. The retardation film is produced by stretching a polycarbonate film and a cycloolefin polymer and coating a film with a liquid crystal. , Sumikalite (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd.), R-film (manufactured by Kaneka Co., Ltd.), Pure Ace (registered trademark) (manufactured by Teijin Co., Ltd.), Zeonoa film (registered trademark) (Made by Optes Co., Ltd.), Essina retardation film (manufactured by Sekisui Chemical Co., Ltd.), Konica Minolta Optical Film (manufactured by Konica Minolta Opto Co., Ltd.), Fuji Film WV FILM (Fuji Photo Film Co., Ltd.) ), NH film for TFT visual improvement use (made by Shin-Nippon Petroleum Co., Ltd.), LC film for STN color compensation use (made by Shin-Nippon Petroleum Co., Ltd.), etc. are marketed.

 1: is a perspective view which shows schematic structure of one Embodiment of the defect detection and defect marking apparatus 10 of the film in this invention. 2 is a simplified cross-sectional view showing the configuration of the defect detection means 25 of the phase difference film among the defect detection and defect marking apparatus 10 of the film.

 In the retardation film 11, even a small defect on the surface, which is small enough to be difficult to visually identify, reduces the display image quality of the liquid crystal display device, which is high definition, and therefore it is not preferable to exist. In addition, even a defect of a relatively wide range may be difficult to discriminate with the naked eye. Even if the defect is difficult to visually detect, it is detected by the defect 13 by the defect detecting means 25.

The retardation film 11 is conveyed at a constant speed in the conveying direction 11 a, detects a defect by the defect detecting means 25, and marking means 14 on the downstream side of the conveying direction 11 a with respect to the defect detecting means. This is installed. The retardation film 11 is taken out in the state wound on the roll 16, and becomes an inspection object.

The defect detecting means 25 includes a lighting device 17, a pair of polarizers 22 and 23 arranged on both sides of the sheet surface of the retardation film 11 as the inspection film and cross nicol parallel to the sheet surface, An optical compensation film 24 disposed between the polarizer and the retardation film and having a birefringence characteristic, an image pickup means 12 for picking up the transmitted light from the illuminating device passing these films, and a luminance signal of the picked-up image It consists mainly of the image processing apparatus 19. As shown in FIG.

The illumination device 17 performs uniform illumination over the whole width direction of the retardation film 11. As the illuminating device 17, tubular light-emitting bodies, such as a fluorescent lamp, and linear light sources, such as a transmission light, are used. The transmission light arranges a powerful light source such as a metal halogen lamp on the axial cross section of the rod-shaped light guide, guides the light incident on the cross section to the side surface between the two cross sections, and functions as a rod-shaped light source. The laser light may be enlarged and irradiated. The light irradiated to the retardation film 11 by the illuminating device 17 is set so that it may become a wavelength or polarization characteristic in which the defect 13 is easy to detect. By the combination of the imaging means 12 and the illuminating device 17, the kind of the defect 13 which can be detected efficiently is determined. In order to make it possible to detect a plurality of types of defects 13, a plurality of sets of combinations of the imaging means 12 and the lighting device 17 are arranged along the conveying direction 11a, and any kind of defects 13 If detected, the marking may be performed by the marking means 14.

The pair of polarizers 22 and 23 are disposed in parallel to both sides of the film surface of the retardation film that is the film to be inspected, and the polarizer 23 linearly deflects the light irradiated from the illuminating device 17 and the retardation film. To enter. The polarizer 22 is arrange | positioned in the polarizer 23 and the cross nicol state (state which orthogonally crossed the polarization axis of the polarizer 22 and the polarization axis of the polarizer 23), and transmitted light which permeate | transmitted the retardation film and the optical compensation film 24 Among them, transmitted light in the polarization axis direction of the polarizer 22 is transmitted. Both the polarizer 22 and the polarizer 23 are known polarizers, and usually, a polarizing plate is used.

The polarizer 23 may be disposed on the front surface of the lighting device 17, and the polarizer 22 may be provided in the camera. Moreover, in order to make a pair of polarizers into a cross nicol state easily, it is preferable to be able to rotate one polarizer. In a state where there is no retardation film, the polarizer can be rotated so that the luminance signal value is minimum and can be easily placed in a cross nicol state.

As the optical compensation film 24, a film having a birefringence characteristic substantially the same as that of the retardation film is preferably used. The optical compensation film is disposed between the retardation film and the polarizer 22 or between the retardation film and the polarizer 23. The optical compensation film is arranged to compensate for the birefringence anisotropy of the retardation film by the birefringence anisotropy. That is, the elliptical polarization of light by the birefringence characteristic of the retardation film returns the linearly polarized light by the birefringence characteristic of the optical compensation film. As a result, the SN ratio of the luminance signal of the defective portion is increased, and the defect can be detected more reliably.

In order to easily compensate for the birefringent anisotropy of the retardation film, it is preferable to allow the optical compensation film to rotate.

The imaging means 12 includes a plurality of cameras 21,... In the width direction. And. The luminance signal of the image picked up by the imaging means 12 is processed by the image processing apparatus 19.

In an image processing apparatus, a threshold value is normally formed in a luminance signal value, and it determines with a defect if it is a signal value more than a threshold value. SN ratio of the luminance signal of a defect part is large, and a defect can be detected with high precision by this method. In order to make the luminance signal of the normal region constant and to make the normal region and the defect clear, it is preferable to set the threshold value and then determine it. 128 gradations are added to the difference between the original image and the shading image obtained by, for example, the average of the normal region, and a waveform image based on the 128 gradations is set. A threshold is set for this image to determine a defect. .

In the marking method of retardation film defect, the method of performing a linear mark on the side edge of the film which is a part containing a defect, the method of marking directly at a defect position, and the defect part of patent document 2 about both sides of the width direction Although the method of marking on the position which becomes the vicinity of the predetermined range in the said can be employ | adopted, a defect part from the point which can ensure reliably that a defect is not included when cutting out a film, and also can suppress the fall of a yield. On the other hand, a method of marking a mark at a position which becomes the vicinity of a predetermined range on both sides in the width direction is preferable.

As for the method of marking on the position which becomes the vicinity of the range prescribed | regulated by the both sides of the width direction with respect to a defect part, specifically, in FIG. 1, the marking means 14 conveys to the surface of the retardation film 11 in a conveyance direction. The linear mark 15 in parallel with 11a is performed.

The conveyance speed of the retardation film 11 is detected by the conveyance speed detection apparatus 18. The output from the conveyance speed detection apparatus 18 is input to the control means 20 with the image processing result from the image processing apparatus 19 which performs predetermined image processing with respect to the image picked up by the imaging means 12. The control means 20 is realized by an industrial PC or the like, for example, to determine the presence or absence of a defect from the image processing result and to detect the position when the defect 13 is present. The control means 20 further adjusts timing based on the output from the conveyance speed detection apparatus 18 so as to mark within a predetermined vicinity of the width direction with respect to the defect present position, and marking means. Activate (14). The marking means 14 includes a plurality of markers 31,... In the width direction. And.

3 shows a thinking manner in which the marking means 14 marks the defect 13 detected by the defect detecting means 25. The imaging means 12 includes a plurality of cameras 21,... In the width direction. , Are placed at regular intervals. Each camera 21,... For example, the imaging device includes a one-dimensional CCD sensor in which 5000 pixels are arranged at a high density. Since the workpiece | work width which is the width | variety of the retardation film 11 of a test object is a range of 800-1300 mm, for example, the inspection area as the imaging means 12 becomes the width of 1300 mm. For this inspection area, six cameras 21,... And place each camera 21,... , Field of view 21a,. And 250 mm. Each camera 21,... , Field of view 21a,. , Are adjacent cameras 21,... , Field of view 21a,. ,, And overlap at the boundary.

In the marking means 14, a plurality of markers 31,... , Are arranged in the width direction at regular intervals, for example 20 mm intervals. Each marker 31,... , Is any one camera 21,... , Field of view 21a,. , Is located on the extension in the conveying direction 11a of. The control means 20 of FIG. 1 includes the respective cameras 21,. When the defect 13 is detected in the image from the marker 13, the markers 31 at the closest positions to sandwich both sides of the defect 13 in the width direction are provided. ,, The selected marker 31,... , Even between markers 31,... If it exists, select it and activate it. Each marker 31,... Is a felt-tip pen type and can form the linear mark 15 in the conveyance direction 11a by making the front end contact the surface of the retardation film. Each marker 31,... When not in use, it is preferable to cover the cap to prevent the solvent, the diluent, and the like from evaporating and deteriorating the pen feel. In general, defects (13) are markers (31),. When it is detected between the positions of and, marks 15 are performed on both sides of the detection position.

FIG. 4 shows an example of a control method of thinking when the control means 20 of FIG. 1 operates the marking means 14 in (a) to perform a mark. 4 (b) and 4 (c) are marks 15b and 15c which are performed on the defects 13b and 13c which are large in the width direction and the longitudinal direction in accordance with the thinking system of FIG. 4 (a). ).

As shown in FIG. 4 (a), the surface of the retardation film 11 is partitioned into a virtual block 40. Each block 40 includes a marker 31 for the width direction,... The squares are 20mm long on each side (41, 42, 43, 44) in accordance with the placement pitch. The sides 41 and 42 are boundaries of the upstream side and the downstream side of the conveyance direction 11a, respectively, and the sides 43 and 44 are boundaries of one side and the other side in the width direction, respectively. When the defect 13 exists inside each block 40, the marker of the position of the sides 43 and 44 of the both sides of the width direction is selected, and a mark is performed. When the defect 13 is caught on any one of the sides 43 and 44, a mark is also made on the side opposite to the side in the block adjacent to the side further as a boundary. Therefore, as shown in FIG.4 (b), about the defect 13b which spreads over several blocks long in the width direction, a mark is performed on the side located between the both sides of the width direction, and all the sides between them. It becomes.

In Fig. 4A, when the defect 13 is caught on any one of the sides 41 and 42, the mark is applied to both sides of the width direction even in an adjacent block bordering the side. . Therefore, as shown in Fig. 4 (c), with respect to the defect 13c that extends in the longitudinal direction and extends across the plurality of blocks, the marks are continuously extended while extending between the blocks on the sides located between both sides in the width direction. Is done.

Moreover, even if a single marker is used, if the conveyance direction 11a and the width direction can be moved at high speed compared with the conveyance speed of the retardation film 11, the mark which makes both sides of the defect 13 intervene It is possible to do. However, the movement control of the marker is complicated, and when a plurality of defects 13 are detected at adjacent positions, it is difficult to make sure marks. If a plurality of markers are moved, many defects 13 can be marked at the same time, but the control becomes more complicated.

Moreover, although the thing of the felt-tip pen type is used as the marking means 14, the marker of another form, such as an inkjet type, can also be used.

Similarly, defect inspection and defect marking can be performed also about a polarizing film. The defect inspection of a polarizing film is made into a polarizing film instead of the retardation film shown in FIG. 1, The method of receiving a transmitted light, image-processing and detecting a defect from a luminance signal, receiving a reflected light, and image-processing a defect from a luminance signal Method of detecting, or arranging the polarizer cross nicol parallel to the film surface of the polarizing film, transmitting from the outside of the polarizing film or the polarizer, receiving the transmitted light transmitted from the polarizer or the polarizing film, and image-processed from the luminance signal It is performed by the method of detecting a defect.

The method of marking a defect of a polarizing film is the same as that of the retardation film, and the method of Unexamined-Japanese-Patent No. 2001-305070 is used preferably.

The retardation film which detected a defect is bonded together with a polarizing film so that it may become a predetermined axial angle. The polarizing film is normally produced by conveying a film having a constant width in the longitudinal direction perpendicular to the width direction, and subjected to defect inspection. Usually, a polarizing film is cut | disconnected to intermediate size, and is bonded with retardation film.

Bonding of retardation film and a polarizing film is performed by the well-known method using an acrylic adhesive etc. 1 to 2 retardation films are normally bonded to a polarizing film according to the objective. That is, there exist some which laminated | stacked the retardation film on the polarizing film so that it might become a predetermined axial angle, and what laminated | stacked the retardation film so that it might become predetermined axial angle on the retardation film of this film as a laminated optical film.

After bonding retardation film and a polarizing film, the defect part is removed and the product of a laminated optical film is obtained. Usually, the laminated optical film is cut into chips of the size of the liquid crystal display panel used, and the chip having the defective portion is removed to be a product of the laminated optical film.

When the retardation film and the polarizing film are bonded, new defects may occur due to the adhesion of foreign matter and fine dust in the adhesive. Therefore, it is preferable that the defects are visually detected after bonding. At this time, the detected defect is manually marked. The defect portion newly detected by the naked eye is removed together with the defect portion detected automatically.

It is preferable to mark the detected defective portion automatically and manually in the above-described method, and to remove the defective portion based on those marks, since it is possible to reliably remove the defective portion.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example  One

Using the apparatus shown in FIG. 1 and FIG. 2, defect detection and defect marking of the retardation film (NH film for TFT time improvement use, retardation: 120 nm, Shin-Nippon Oil Co., Ltd. product) were performed by the method mentioned above. .

As an optical compensation film, the above-mentioned retardation film which is a test film was used, it arrange | positioned at right angles to the conveyance direction of a test film, and the anisotropy of the retardation film birefringence which is a test film was compensated for by the anisotropy of the birefringence.

As a polarizer, a polarizing film (Sumikaran (registered trademark) and Sumitomo Chemical Co., Ltd. product) was used.

The conveyance speed of the retardation film was 6 m / min, the defect value was automatically detected by setting the threshold value as 178 of +50 to the waveform image based on 128 gradations obtained by image processing, and the mark was detected automatically.

As a result, the number of defect markings was 17 pieces / m on average.

Next, this retardation film was bonded to a polarizing film (Sumikaran (registered trademark) SBP grade, Sumitomo Chemical Co., Ltd.) and a retardation film (Sumikarite (registered trademark) SES grade, Sumitomo Chemical Co., Ltd. product). It bonded to the retardation film side of a film through an adhesive, and obtained the laminated optical film.

This laminated optical film was cut out to about 50 cm in width and width for easy handling, and visual inspection was performed to manually mark a defect caused by foreign matter or the like mixed at the time of bonding.

Next, the laminated optical film which performed this mark was cut out by the chip of a 2.2 inch size. Of these chips, the automarked and manually marked chips were removed and the rest was used as products.

When the product of the laminated optical film obtained in this way is bonded to a liquid crystal display panel, and the quality of a to-be-adhered optical film is judged by the good / bad of an image, a defective rate will be 1% or less.

Comparative example  One

It carried out similarly to Example 1 except not having automatic defect detection and automatic defect marking of retardation film (NH film for TFT time improvement uses, retardation: 120 nm, Shin-Nippon Petroleum Co., Ltd. product).

When the product of the laminated optical film thus obtained is bonded to the liquid crystal display panel and the quality of the laminated optical film is judged by the good / poor image, the defective rate is about 10%.

As mentioned above, according to this invention, the laminated optical film formed by bonding the polarizing film and retardation film with few defects is obtained.

Claims (10)

In the method of bonding a polarizing film and retardation film and manufacturing a laminated optical film, The retardation film having a constant width is conveyed in the longitudinal direction perpendicular to the width direction, and at that time, a pair of polarizers are arranged cross nicol parallel to the film surface on both sides of the retardation film, and the polarizer and the retardation film The optical compensation film which has a birefringence characteristic is arrange | positioned in between, it transmits from the outside of one said polarizer, receives the transmitted light transmitted from the said other polarizer, detects a defect from the brightness signal, and then joins with a polarizing film The defect part is removed after that, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method of claim 1, Wherein the optical compensation film has a birefringence characteristic substantially the same as the birefringence property of the retardation film, and the optical compensation film is disposed so as to compensate for the birefringence anisotropy of the retardation film by the birefringence anisotropy of the optical compensation film. The manufacturing method of a laminated optical film. The method of claim 1, After bonding with the said polarizing film, a defect is visually detected further, and it combines with the defect part of the said retardation film, and removes a defect part, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method according to claim 1 or 3, Bonding with the said polarizing film which detected the defect, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method of claim 4, wherein Transmitting to the said polarizing film, receiving the reflected light or transmitted light, and detecting the defect of the said polarizing film from the brightness signal, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method of claim 4, wherein The polarizer is arranged to cross nicol parallel to the film surface of the polarizing film, and the light is transmitted from the outside of the polarizing film or the polarizer to receive the transmitted light transmitted from the polarizer or the polarizing film, and defects are generated from the luminance signal. The manufacturing method of the laminated optical film characterized by the above-mentioned. The method according to claim 1 or 4, The defect part WHEREIN: The mark is performed and a defect part is removed based on the mark, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method of claim 7, wherein The manufacturing method of the laminated optical film characterized by performing a mark in the position which becomes the vicinity of the predetermined range with respect to the defect part in the both sides of the width direction. The method of claim 8, When the position to mark on both sides of the width direction is separated by more than a predetermined space | interval, it marks also in the middle, The manufacturing method of the laminated optical film characterized by the above-mentioned. The method according to claim 1 or 4, After bonding with the said polarizing film, a defect is visually detected further, a mark is also made about the defect part, and the defect part is removed based on a mark, The manufacturing method of the laminated optical film characterized by the above-mentioned.

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