JP2003316278A - Display device having optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the generation of an optical interference fringe between the surface shape of an optical film and a lighting pixel, by arranging the axis of the flowing direction of a web roll for the optical film so as not to be parallel to the axis of an information electrode of a display device, which relates to an antireflection film provided to the display device. <P>SOLUTION: By providing the optical film so that the direction of the roll width axis and the axis of the roll flowing direction for the optical film are parallel to neither the lengthwise direction of the display device, namely the axis of the information line, nor the widthwise direction, namely the axis of a scanning line electrode, the display device can be provided, which does not generate the optical interference fringe associated with the deterioration in the image quality. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film attached to the outermost surface of a polarizing plate of a liquid crystal display such as a personal computer and a word processor or an optical film attached to the surface of a CRT for the purpose of preventing reflection and electromagnetic waves. , An optical film attached to the surface of a glass or plastic protective plate installed on the front surface of the display surface for the purpose of protecting the display surface of a plasma display, etc., and in particular, an optical film for preventing the occurrence of interference fringes during image display And a display device provided with the optical film.

[0002]

2. Description of the Related Art An optical film attached to the surface of a polarizing plate of a liquid crystal display or an optical film attached to the surface of a CRT for the purpose of preventing reflection and electromagnetic waves.
As an optical film attached to a protective plate of a plasma display, a highly transparent PET (polyethylene terephthalate) film or a TAC (triacetate cellulose) film is often used as a film substrate. Such a PET film or TAC film raw material is usually manufactured in a roll form, and for example, a width of 1000 mm and a length of several tens to several hundreds of meters are used. On the film of this base material, an ionizing radiation curable resin such as an electron beam curable resin or an ultraviolet curable resin having a scratch resistance effect, or
A hard coat layer of a siloxane-based thermosetting resin is formed. In general, a roll coating method is generally used for forming such a hard coat layer. Further, an antireflection layer is formed thereon to form an antireflection film. For forming such an antireflection layer, M having a low refractive index is used.
Inorganic materials such as gF ₂ and SiO ₂ or metal materials are deposited,
A thin film is formed into a single layer or multiple layers by sputtering, plasma CVD or the like, or a coating film of a low refractive index resin composition containing an inorganic material such as low refractive index MgF ₂ or SiO ₂ or a metal material is formed. It is performed by forming a layer or multiple layers. In recent years, in addition to antireflection layers as optical films, multi-functionalization has been achieved by laminating a low resistance film for electromagnetic wave shielding, an antifouling treatment film that makes fingerprints difficult to attach, and a film with infrared cut characteristics. Has been done.

When used for a display device, the predetermined external size is almost rectangular, and in rare cases, square. In cutting out of a predetermined size or a size that can cut out a plurality of predetermined sizes, if a processed film can be formed in a roll form of an optical film by a roll coating method or the like for a plurality of films including an antireflection film, a finished product, As shown in FIG. 5, in order to increase the number of sheets taken from the original film, it was usual to make the side of the outer size parallel to the axis in the roll width direction. In addition, when the treatment film cannot be formed on the upper surface of the hard coat layer in a roll form like a method such as vapor deposition, the vapor deposition film is cut after cutting to a predetermined size or a size capable of cutting a plurality of predetermined sizes. In this case as well, the predetermined size or the size capable of cutting out a plurality of predetermined sizes is also the case that the side of the outer size is aligned with the axis in the roll width direction in order to increase the number of sheets taken from the original film as shown in FIG. It was usually parallel.

In the case of a liquid crystal display device, the optical film produced in this manner is directly attached to the polarizing plate surface on the observation surface side, directly attached to the CRT surface, or placed on the front surface like a plasma display. It is used by being attached to the surface of the protective plate.

[0005]

However, when the optical film produced by the above-mentioned conventional manufacturing method is provided in the display device, the surface shape of the film may be changed depending on the display of an image, that is, the lighting state of the pixel. And pixel lighting,
The regularity of non-lighting causes optical interference, which causes a problem that the appearance of an image is significantly deteriorated for the user.

Regarding the phenomenon of occurrence of interference fringes, the present inventor will explain in detail the results of analysis of the phenomenon and its cause.
According to the measurement results by the present inventors, as shown in FIG. 4, on the surface of the PET film, which is the original film of the optical film, the number of parallel to the axis in the width direction of the roll and parallel to the axis of the roll flow direction is several. A waviness with a height difference of about several μm occurs at a pitch of 10 mm. Further, a hard coat layer is formed on this, but in general, by coating the hard coat layer,
The haze value is reduced as compared with the PET film which is a base material. From this, it is known that the irregularities on the surface of the hard coat layer are fine. That is, the flatness of the surface is improved. When the hard coat layer is applied, it follows the shape of the surface of the PET film of the base material, but when the hard coat layer is applied by the roll coating method, the hard coat layer is newly coated on the surface depending on the conditions of the hard coat layer application. A swell is formed. Although the pitch is fine and the height difference is small, undulations similar to those of the original fabric of the PET film shown in FIG. 4 occur. That is,
The wobbling of the roll in the left-right direction is parallel to the width direction of the roll due to the wobbling of the roll in the vertical direction, and the wobbling is performed flat in the roll-flow direction. According to the measurement by the present inventor, undulations having a height of 0.1 to 0.2 μm are generated at a pitch of several mm to several tens of mm in both the width direction of the roll and the flow direction of the roll. Further, even if the above-mentioned multifunctional film including the antireflection layer is formed on the hard coat layer, the film thickness thereof is very thin and the surface shape is maintained to be the same as the surface shape of the hard coat layer. .

The case where the optical film thus manufactured is applied to an actual display device will be described. FIG. 6A shows
A cross-sectional view of a display device showing a conventional example, FIG.
It is the figure which looked at the display device of (a) from the top, and is a figure which shows the relationship with the axis | shaft of the original film in a display area. In the display device of the conventional example, the arrangement of the pixels, the axis in the roll width direction of the optical film, and the axis in the roll flow direction have the relationship shown in FIG. 6B. FIG. 7A shows a pixel of a display device having a so-called color filter stripe array. 70
Reference numerals 1, 702 and 703 denote Red display pixel columns and G, respectively.
The ren display pixel column and the Blue pixel display column are shown. Figure 7
In (b), in the case of monochrome full-color red display, the two pixels of the green pixel row 705 and the blue pixel row 706 are black pixels in the non-lighting state (hatched) in parallel with the scanning line, and the red pixel row One column 704 will be illuminated. In this case, the light / dark / dark and light / dark / dark repeating patterns are continuous for each pixel pitch. The repetitive regularity in this display state and the flat waviness of the surface shape of the film cause optical interference. That is, it is an optical interference phenomenon of the regularity of the display pattern and the regularity of the undulation of the surface shape. Therefore, the interference fringes are observed in a small area even when the display pattern is not entirely red but partially red. Furthermore, the same phenomenon may occur in green display and blue display. The interference fringes are particularly noticeable when the bright part displays the maximum brightness and the dark part displays the minimum brightness.

Further, in the case of a display pattern having regularity for each line parallel to the scanning line side, for example, black and white display for each line, interference fringes may be observed.

In a display device having a low aperture ratio (a small light emitting area), a non-light emitting dark portion is formed between pixels other than the display pixels, and a lighting portion is a bright portion, and similar regularity of light and dark occurs. Interference fringes may occur due to the relationship between the regular pitch and the surface shape of the optical film.

Since these interference fringes are optical interference between the pixel pitch or pixel arrangement and the surface shape of the film, they are not observed in all display devices. It is also related to the distance between the film and the display element. However, it is considered that the probability of occurrence of such interference fringes increases due to the panel outer size and the number of pixels of display devices that have been diversified in recent years.

[0011]

Since the occurrence of interference fringes is the cause as described above, display is performed in a direction in which neither side of the outer shape of the optical film is parallel to the roll width direction axis and the roll flow direction axis. If it is arranged in the device, the occurrence of interference fringes can be prevented. That is, the roll width axis direction and roll flow direction axis of the optical film are not parallel to both the vertical direction of the display device, that is, the information line electrode axis, and the horizontal direction, that is, the scanning line electrode axis, and the optical film is arranged. Therefore, it is an object of the present invention to provide a display device in which optical interference fringes accompanied by image quality deterioration do not occur.

[0012]

Embodiments of the present invention will be described with reference to the drawings. FIG. 3 shows a method of manufacturing the optical film of the present invention. As described in the conventional example, a film made from a roll, which is an original fabric, has undulations on the film surface parallel to the axis of the roll width direction and the axis of the roll flow direction. Since the occurrence of interference fringes is the cause as described above, the axis in the roll width direction and the axis in the roll flow direction may be prevented from being parallel to the display pixel.

Since it is more mass-producible to handle with a roll when forming the hard coat layer, it is better to cut out to a predetermined size required for the display device after forming the hard coat layer. After that, when a multilayer antireflection film or the like is formed by vapor deposition, it may be cut into a predetermined size or a predetermined size for cutting a plurality of predetermined sizes after forming the hard coat. By doing so, it is more cost effective than forming an expensive vapor deposition film and then cutting out a predetermined size to cut out a film with an expensive vapor deposition film and discarding unnecessary portions.

When a low-resistance film is formed for an antireflection film or an electromagnetic wave shield, an antifouling coating layer is formed to prevent fingerprints from being formed, and other multi-functional films are formed by rolls, After the formation of all the films is completed, as shown in FIG. 3, a predetermined size or a predetermined size may be cut into a predetermined size for cutting a plurality of sheets.

FIG. 1 (a) is a sectional view of a display device to which the optical film of the present invention is attached, and FIG. 1 (b) is a view of the display device from above, showing the axis of the original film in the display area. It is a figure which shows the relationship with. Reference numeral 101 denotes an optical film manufactured by the present invention, which is directly attached to the polarizing plate 102 on the observation surface side of the liquid crystal display device 103. 1
Reference numeral 04 is a polarizing plate attached to the back surface side. 1
The optical film of No. 01 is obtained by rotating the original fabric roll at a certain angle in the plane as shown in FIG. By cutting in this way, as shown in FIG. 1B, the display pixel, the axis of the optical film in the roll width direction, and the axis of the roll flow direction have an angle and are not parallel to each other. The angle between the axis of the information electrode and the axis in the roll flow direction is θ, as shown in FIG. Normal computer display pixel pitch 200-300
In the case of μm, θ is shifted by several degrees, that is, by making the roll width direction axis and the roll flow direction axis of the display pixel and the optical film not parallel to each other,
The aforementioned interference fringes become inconspicuous.

On the other hand, in the case of a high-definition liquid crystal display with a pixel pitch of 100 μm or less, from the result of the study by the present inventor,
Although the appearance of the interference fringes will change if θ is only a few degrees, it cannot be improved to a level where the deterioration of image quality is not a problem, and the interference fringes are almost eliminated by rotating it by 15 ° or more. On the contrary, if the rotation angle is too large, the rotation angle becomes parallel to the direction of the electrodes on the scanning line side, which causes interference fringes of horizontal stripes. Θ at that time
Was about 80 °. Therefore, θ is 15 ° or more and 80 °
Within the range below, the occurrence of interference fringes can be prevented. However, considering that the cost increases due to the decrease in the number of films taken from the original film, θ is 15 to 30 °.
And 65 ° to 80 ° are optimal.

The second embodiment is a plastic plate or glass which is a separate member in which the film prepared by the method described in the first embodiment is arranged at a position apart from the display portion such as a plasma display. It is an example of pasting together.
2A is a sectional view of the display device according to the second embodiment, and FIG.
It is a figure which shows the relationship with the axis | shaft of the original film in the display area which looked at it from above at (b). Reference numeral 204 is a display device such as a plasma display. In FIG. 2, an optical film having an antireflection function, an electromagnetic wave shielding function, and the like is attached to both surfaces of a glass or plastic protective plate 202 arranged on the front surface of the display device. Protection plate 202
There is a case where the optical film 201 is attached to both surfaces of the sheet, or a case where the optical film is attached to only one side and the other surface of the protective plate 202 is directly subjected to surface treatment such as AR coating and AG coating. It is also effective in some cases. In the case of a plasma display, the pixel pitch is coarser than that of a display device for a computer display, and since the protective plate is arranged at a distance from the display device, the interference fringes are inconspicuous, and the above-mentioned θ is several degrees. There was some effect. However, even for plasma displays with small pixel pitch specifications,
It is desirable that β = 15 to 30 ° and 65 to 80 °. However, when the antireflection film is attached to both sides, the front surface and the back surface are attached to each other in order to prevent interference fringes due to the surface shape of the antireflection film surfaces, for example, when viewed from the observation surface side, the waviness axis of the film It is better not to let them be in the same direction.

A third embodiment will be described. The third embodiment is a case where an optical film is attached to the tube surface of a CRT. Although illustration is omitted, the relationship between the scanning line direction of the display pixel of the CRT, the axis of the roll width of the optical film, and the axis of the roll flow direction is the same as in the first and second embodiments. By arranging at least the axis of the information electrode and the axis of the original roll flow direction not to be parallel, the interference fringe phenomenon is alleviated. Desirably, the angle θ formed between the axis of the information electrode and the axis of the original roll flow direction is 15 to 30 ° and 6 as in the first embodiment.
The optimum angle is 5 ° to 80 °. The optical film may be rotated by an angle θ to cut out a predetermined external size and then attached, or when the optical film is attached, the external size of the optical film is larger than the display surface and the required θ rotation is obtained. If it is possible, cutting out of a predetermined external size will be handled on the pasting device side in the same manner as the conventional example,
It may be attached with an angle of θ.

[0019]

As described above, the roll width axis direction and the roll flow direction axis of the optical film are either in the vertical direction of the display device, that is, the information line electrode axis, or in the horizontal direction, that is, the scanning line electrode axis. By disposing the optical films not parallel to each other, it is possible to provide a display device in which optical interference fringes accompanied by image quality deterioration are not generated.

[Brief description of drawings]

FIG. 1A is a sectional view of a display device showing a first embodiment of the present invention. (B) A plan view of a display device showing a first embodiment of the present invention.

FIG. 2A is a sectional view of a display device showing a second embodiment of the present invention. (B) A plan view of a display device showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a method for cutting out an optical film from a raw film according to the present invention.

FIG. 4 is a view showing a surface shape of a raw PET film (or after coating with a hard coat).

FIG. 5 is a diagram showing a method of cutting an optical film of a conventional example from a raw film.

FIG. 6A is a sectional view of a conventional display device. (B) The top view of the display device of a prior art example.

FIG. 7A is a diagram showing a pixel arrangement of a display device. FIG. 7B is a diagram showing a lighting state of a pixel of the display device.

[Explanation of symbols]

101, 201 Optical film according to the present invention 102, 602 Upper polarizing plate 103,603 LCD panel 104,604 Lower polarizing plate 202 Protective plate 203 Plasma display 605, 701, 704 Red pixel columns 606, 702, 705 Green pixel columns 607, 703, 706 Blue pixel columns

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H091 FA37X FA37Z FA50X FA50Z                       GA01 KA10 LA16                 2K009 AA02 AA15 BB24 DD03 EE03                       EE05                 5G435 AA01 AA09 BB02 BB06 BB12                       CC09 DD11 FF05 GG33 HH02                       HH03

Claims (3)

[Claims] 1. A hard coat layer containing a resin as a main component is formed on the surface of a transparent film, and a multi-functional film such as an antireflection film, an electromagnetic wave shielding film, an antifouling film and an infrared cut film is formed on the hard coat layer. A film selectively formed according to the purpose, with respect to the axis of the direction of the information electrode of the display device, the undulation of the surface shape of the transparent film along the axis of the width direction of the raw roll at the time of manufacturing the transparent film On the other hand, a display device provided with an optical film, which is arranged in the display device so as not to be parallel to the waviness of the surface shape of the transparent film along the axis of the flow direction of the roll. 2. The angle between the axis in the direction of the information electrode of the display device and the waviness of the surface shape of the transparent film along the axis in the flow direction of the original roll during the production of the transparent film is 15 to 80. The display device provided with the optical film according to claim 1, wherein the display device is arranged so as to be in a range of °. 3. The angle between the axis in the direction of the information electrode of the display device and the undulation of the surface shape of the transparent film along the axis in the flow direction of the original roll during the production of the transparent film is 15 to 30. The display device provided with the optical film according to claim 1, wherein the display device is arranged so as to be in a range of an angle of 65 ° to 65 °.