CN100401113C - Anti-glare film and image display device - Google Patents

Abstract

The present invention provides an anti-glare film that reduces bright spots on a screen without sacrificing anti-glare properties and a method for producing the same, and provides an image display device using the anti-glare film that is excellent in visibility. An anti-glare film (20) is provided, which is a kind of anti-glare film with fine concave-convex shapes formed on the surface, the area higher than the average height of the concave-convex area is a raised area, and the area lower than the average height of the concave-convex area is In the concave area, calculate the projected area of each protrusion or the projected area of the depression, calculate the frequency of the raised area or the concave area according to the specified area marking line, and then use the above-mentioned specified area marking calculation table according to the area × frequency The frequency of the apparent area, and use a histogram to represent the frequency of the apparent area of the raised or depressed area. The peak appears at a position below 300 μm ² , and the half-spectrum amplitude of the peak is below 60 μm ² . The anti-glare film (20) is arranged on the viewing side of an image display means such as a liquid crystal panel to constitute an image display device. After the photoetching process of forming the concave-convex shape on the photoresist film (12) formed on the substrate (11) by photoetching, electroforming metal ( 17), after the concave-convex shape is copied on the metal (17), the metal plate (17) that has copied the concave-convex shape is peeled off from the photoresist film (13), and the electroforming mold making of the mold (18) is made Process, using the metal plate (18) with the concave-convex shape copied as a mold, the concave-convex film production process of replicating the concave-convex shape on the surface of the metal plate on the surface of the film (20), when manufacturing the anti-glare film (20) with the concave-convex shape on the surface, The photolithography process described above is performed by exposing the photoresist film (12) through a photomask having at least two patterns of different sizes, followed by development.

Description

Anti-glare film and image display device

technical field

The present invention relates to an anti-glare film that can be applied to optical applications such as polarizing films in image display devices, especially when applied to high-definition image display devices, it is difficult to produce bright spots and other phenomena, and high visibility can be ensured. The invention of revolutionary anti-glare film. The present invention also relates to an image display device using the antiglare film.

Furthermore, the present invention relates to an invention relating to a method for producing an anti-glare film applied to optical applications such as polarizing films in image display devices. Described in detail, it is an invention related to an appropriate production method of an anti-glare film effective in obtaining a specific reflection curve.

Background technique

For image display devices such as liquid crystal display devices, when external light enters the image display surface, its visibility will be significantly affected. Display devices are used in applications such as televisions and personal computers that emphasize image quality, video cameras and digital cameras that are used outdoors under strong sunlight, and reflective liquid crystal display devices such as mobile phones that use reflected light to display. It is a common case to perform processing to prevent these reflections of light on the surface. Regarding the treatment for preventing reflected light, there is a big difference between non-reflection treatment, which uses an optical multilayer film to create disturbances, and anti-glare treatment, which dilutes the reflected light by forming unevenness on the surface to scatter the incident light. The former non-reflective treatment needs to form a multilayer film with a uniform optical film thickness, so there is a problem of high cost. On the other hand, since the latter anti-glare treatment can be realized at a relatively cheap price, it is used for large-scale personal computers and monitors.

Anti-glare films can be produced by, for example, coating a UV-curable resin with a filler dispersed on a transparent substrate, drying the resin by irradiating ultraviolet rays, and randomly forming irregularities on the surface of the filler. manufacture. Furthermore, there have been many proposals to form fine unevenness on the surface of a film used in an image display device to achieve anti-glare properties. For example: in Japanese Patent Early Publication No. 2003-4903, a kind of anti-glare layer is provided on a transparent support body, and the anti-glare film with concave-convex shape on the surface is proposed. The cross-sectional area is 1,000 μm ^or less. Here, the anti-glare film having the above-mentioned concave-convex shape is made by coating a transparent support with an ultraviolet curable resin dispersed with particles with an average particle diameter of 0.2 to 10 μm, and then irradiating it with ultraviolet rays. Manufactured by hardening methods.

On the other hand, in the Japanese Patent Laid-Open Publication No. 6-1685 1 and the Japanese Patent Laid-Open Publication No. 7-124969, it is disclosed that UV curing of a transparent base material having an ultraviolet curable resin layer In the state where one side of the molded resin is closely bonded to the pre-existing concave-convex film, the UV-curable resin layer is irradiated with ultraviolet rays, and the concave-convex shape is copied on the UV-curable resin. However, Japanese Patent Laying-Open No. 6-16851 discloses only a method of coating a resin composition composed of a filler and a binder on a base film as a film having a concavo-convex shape in advance. In Japanese Patent Laid-Open Publication No. Hei 7-124969, only a method of stretching a film filled with a filler and a method of sandblasting the film afterwards are disclosed.

In addition, Japanese Patent Laid-Open Publication No. 2002-365410 discloses an anti-glare film, which is an optical film with fine concavo-convex shapes formed on the surface. Light is incident in the direction of -10° from the normal, and the reflected light curve satisfies a specific relationship when only observing the reflected light from the surface.

In Japanese Patent Laid-Open Publication No. 2003-177207, an antireflection film is disclosed. The average height (Rc) of the curve element is 0.1 to 30 μm, and the number of protrusions per 0.01 mm ² on the concave and convex surface is 1 to 1,000 resin layers. In this concave and convex surface, the antireflection film 15-100% of the parallel planes have an inclination angle of 0-5°, and 15-100% of the parallel planes are formed by protrusions. In this patent document 3, in order to form such a concavo-convex shape, an underlying negative matrix film is used, but the specific method of making this underlying negative matrix film is not disclosed.

Contents of the invention

The problem that the invention hopes to solve

Utilize the known anti-glare treatment film before, especially the anti-glare film obtained by dispersing the filler, because the filler is randomly arranged during coating, so the density distribution and stretching of the filler will cause the formation of spots on the surface. Density distribution of bumpy shapes. In addition, in industrial production, aggregation of the filler tends to occur, which may cause unevenness.

When such a conventional anti-glare film is used in combination with a high-definition liquid crystal panel, although the cause may not be certain, bright spots will appear on the display, making it difficult to obtain sufficient visibility. In order to reduce the density distribution of the concavo-convex shape, although the proportion of the filler can be reduced, sufficient anti-glare properties cannot be obtained at this time. On the other hand, if the proportion of the filler is too large, although the anti-glare property can be obtained, However, there will be a problem that the diffusion ratio increases and the contrast decreases.

On the other hand, in an anti-glare film for an image display device, since it is preferable to have a plurality of concavo-convex shapes in one pixel, the size of each concavo-convex shape needs to be smaller than the pixel size of the image display device to be applied. In addition, in order to optimize the reflection of light caused by uneven shapes using such a size, it is necessary to design the shape and arrangement of the unevenness, but at this time, it is necessary to consider the geometrical optics elements generated by each uneven shape with respect to reflected light. , and wave optics elements such as interference and diffraction of light caused by the small size of the concave-convex shape. For example, in the anti-glare film applied to image display devices such as liquid crystal display devices and plasma displays, when irregularities of the same size from a few μm to tens of μm are randomly arranged, interference due to the same size of the unevenness will occur As a result of diffraction, the reflected light produced by the concave-convex shape of the surface appears red, and there are problems such as strong reflected light at a certain reflection angle.

In Japanese Patent Publication No. 2004-4308 (priority claim: Japanese Patent Application No. 2003-8744), the inventors of the present invention proposed the following proposal, that is, after forming on the base material by photolithography, The process of forming the concave-convex shape on the photoresist layer, after electroforming metal on the concave-convex surface of the obtained photoresist layer, the metal is peeled off from the photoresist layer, and the photoresist The process of replicating the concave-convex shape on the layer on the metal, using the metal plate with the concave-convex shape as a mold, and the process of replicating the concave-convex shape on the surface of the film to produce an anti-glare film with concave-convex shapes on the surface.

The present invention is completed with reference to these actual conditions, and its purpose is not to sacrifice the anti-glare property, but to provide an anti-glare film that can reduce bright spots on the screen. Another object of the present invention is to provide an image display device having excellent visibility without bright spots on the screen using such an antiglare film.

In addition, another object of the present invention is to provide a method for producing an anti-glare film having excellent optical properties by controlling the shape of concavities and convexities formed on the surface.

Based on this purpose, the inventors of the present invention conducted intensive studies and found that the density distribution of the unevenness region on the thin film formed with unevenness has a great influence on the performance of the bright spot, and that by properly controlling it, it can be achieved. A high-performance anti-glare film can be obtained, and further various researches have been conducted, and the present invention has been completed. Furthermore, according to the method proposed in the above-mentioned Japanese Patent Early Publication No. 2004-4308, further studies have been carried out, and it has been found that a high-performance anti-corrosion film can be obtained by studying a photomask in the process of forming a concave-convex shape by photolithography. glare film.

The means to solve this problem

That is, according to the present invention, it is possible to provide an anti-glare film in which fine concavo-convex shapes are formed on its surface, regions higher than the average height of the concavo-convex shapes are convex regions, and regions lower than the average height of the concavo-convex shapes are convex regions. For the concave area, the projected area of each convex area or the projected area of the concave area is obtained, and the frequency of the convex area or concave area is obtained by using the specified area line, and further according to the area × frequency, the above-mentioned stipulations are used The frequency of the apparent area is calculated by the area reticle, and when the frequency of the area of the raised or depressed area is represented by a histogram, the peak appears at a position below 300 μm ² , and the half-spectrum amplitude of the peak is at ^60μm2 or less.

It is more preferable that the above-mentioned peak appears at a position below 150 μm ² , and it is more preferable that the half-spectrum amplitude of the above-mentioned peak is greater than 10 μm ² .

It is favorable for these anti-glare films to have a reflectance in a direction deviated from the regular reflection angle by 20° to 0.001% or less. In addition, it is favorable that the 45° reflection visibility measured using an optical comb having a width of 1.0 mm between the dark part and the bright part is 50% or less. In addition, it is advantageous that the total value of the transmitted visibility measured using four kinds of optical combs having a width of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm in the dark area and the bright area is 200% or more. In these antiglare films, it is favorable that the diffusion ratio is 15% or less.

Furthermore, according to the present invention, it is possible to provide an image display device using an anti-glare film comprising any of the above-mentioned anti-glare films and image display means, the anti-glare film being disposed on the viewing side of the image display means.

According to the present invention, there is provided a method for producing an anti-glare film having concavo-convex shapes on the surface, which includes a photoetching process of forming concavo-convex shapes on a photoresist film formed on a substrate by photoetching, Electroforming metal on the concave-convex surface of the photoresist film, copying the concave-convex shape on the metal, peeling off the metal plate with the concave-convex shape copied from the photoresist film to make the electroforming mold manufacturing process, this The metal plate with the uneven shape copied is used as a mold, and the uneven shape on the surface is copied to the surface of the film. The uneven film production process. In the above-mentioned photolithography process, the photoresist film is exposed through a photomask having at least two patterns of different sizes, and then developed to produce an anti-glare film.

In this method, the pattern formed on the photomask is preferably such that the diameter of the largest pattern is not less than 1.1 times and not more than 2 times the diameter of the smallest pattern. Furthermore, since a pattern is formed on the photomask, it is advantageous to set the ratio of the total areas occupied by at least two patterns with different sizes within a range of 0.7 to 1.3.

The above-mentioned exposure through a photomask is preferably performed by disposing a photomask at a position spaced from the surface of the photoresist film for short-distance exposure. And, when the interval between the photomask and the photoresist film surface is set as L (μm), and the average diameter of the pattern of the photomask is set as D (μm), the exposure at L/D It is favorable to carry out under the condition that the value of ² is not less than 1.3 and not more than 2.8.

In order to maintain the symmetry of the translation, the photomask can be formed by arranging a plurality of unit elements with a specified area. Moreover, the metal plate with the concave-convex shape copied is used as a mold, and when the concave-convex shape is copied on the surface of the film, the metal plate can be rolled on the surface of the drum with the concave-convex surface as the outside for the concave-convex film production process.

The effect of the invention

The anti-glare film of the present invention is a film in which the unevenness of the surface is appropriately controlled. When it is applied to image display devices such as liquid crystal display devices, especially high-definition image display devices, it can effectively prevent bright spots and other obstacles. The emergence of visual phenomena. Therefore, an image with excellent anti-glare effect and high visibility can be displayed. In particular, by simultaneously controlling the optical properties of the film, its effect is even more pronounced.

According to the present invention, an antiglare film excellent in optical performance can be produced with good productivity and good reproducibility.

Description of drawings

FIG. 1 is a perspective view schematically showing the surface shape of an antiglare film.

Fig. 2 is a three-dimensional contour diagram in which the height of each point is plotted on the surface of a certain part of the anti-glare film.

3 is a two-dimensional contour map of a certain part of the surface of the anti-glare film, in which regions (protrusions) with a higher than average height are shown in white, and regions (recesses) with a lower than average height are shown in black.

Fig. 4 is a histogram showing the frequency of each convex and concave area observed on the surface of the anti-glare film relative to the area, the horizontal axis represents the area (unit is μm ² ), and the vertical axis represents the convexity of the area The frequency (unit is the number) displayed in the raised or depressed area.

FIG. 5 is an example of a histogram on the vertical axis represented by area×frequency (unit μm ² ) based on the data in FIG. 4 .

6 is a graph showing a method of calculating the half-spectral amplitude of the peak in the histogram of the apparent area of the convex or concave region, and is a histogram showing the range between 0 and 200 μm ² on the horizontal axis of FIG. 5 .

Fig. 7 is a diagram showing one of the production methods of the antiglare film according to the present invention in longitudinal cross-sectional view for each step.

Fig. 8 is an enlarged schematic cross-sectional view showing part of Fig. 7(B) .

Fig. 9 is a perspective view illustrating the relationship between the regular reflectance and the reflectance at an angle θ inclined from the regular reflection direction toward the film side.

Figure 10 shows that when the regular reflectance for incident light is taken as R(0), and the reflectance of the angle θ inclined from the regular reflection direction toward the film side is taken as R(θ), R(θ) is R(0 ) is a schematic diagram of a case where the maximum value simply decreases with an increase in θ.

FIG. 11 is a perspective view for explaining the regular reflection angle and the reflectance in a direction deviating from the angle by 20°.

Fig. 12 is an enlarged view showing the height information displayed in a hierarchical manner in the range of about 480 μm in the vertical direction and about 640 μm in the horizontal direction of the anti-glare film obtained by Embodiment 1, and the gray scale indicating the height is shown horizontally on the right side.

13 is a histogram showing the frequency of appearance of each raised or depressed region observed on the surface of the anti-glare film obtained in Embodiment 1, plotted against the area.

FIG. 14 is a histogram in which the vertical axis is represented by frequency×area (unit: μm ² ) based on the data in FIG. 13 .

Explanation of symbols:

1...the main plane of the anti-glare film

2...The projection surface of the film

3...Protrusions on the surface of the film (areas of higher than average height)

4...Depressions on the surface of the film (areas below average height)

5...principal normal of the film

6...the direction of incident light

7...the plane containing the principal normal of the film and the direction of the incident light

8...Direction of positive reflection

9...The direction that deviates from the regular reflection angle by 20°

ψ...Incident angle (=regular reflection angle)

11...Substrate for photoresist film formation

12...Photoresist film

13...A photoresist film with concavo-convex shape is formed

14... photomask

15...the exposure beam after passing through the photomask

17... electroformed metal

18... Embossed mold

20...Anti-glare film

21...Transparent base film

22...Ultraviolet curable resin or its cured product

25...Normal direction of anti-glare film

26...the plane including the normal of the anti-glare film and the direction of the incident light

30...the direction of incident light

32...Direction of positive reflection

34...From the regular reflection direction to the anti-glare film side, only the direction of the angle θ is inclined

ψ...Incident angle (=regular reflection angle)

θ……The inclination angle from the regular reflection direction toward the anti-glare film side

Detailed ways

Hereinafter, the present invention will be described in further detail with reference to the drawings as appropriate. In the accompanying drawings, Fig. 1 is a perspective view showing an outline of the surface of an antiglare film. Fig. 2 is a three-dimensional contour map in which height curves of various points are drawn on the surface of a certain part of the anti-glare film. 3 is a two-dimensional contour map of a certain part of the surface of the anti-glare film, in which regions (protrusions) with a higher than average height are shown in white, and regions (recesses) with a lower than average height are shown in black. Fig. 4 is a histogram plotting the frequency with respect to the area of each convex and concave region observed on the surface of the antiglare film. FIG. 5 is an example of a histogram showing the vertical axis by area×frequency based on the data in FIG. 4 . Fig. 6 is a schematic diagram showing a method for calculating the half-spectrum amplitude of the peak in the histogram of the apparent area of the raised or depressed region, which is a histogram between 0 and 200 μm ² on the horizontal axis of Fig. 5 is enlarged. Fig. 7 is a schematic view showing an example of the method for producing an anti-glare film according to the present invention in longitudinal cross-sectional view for each step. Fig. 8 is an enlarged schematic cross-sectional view showing part of Fig. 7(B) . Fig. 9 is a perspective view illustrating the relationship between the regular reflectance and the reflectance at an angle θ inclined from the regular reflection direction toward the film side. Figure 10 shows that when the regular reflectance for incident light is taken as R(0), and the reflectance of the angle θ inclined from the regular reflection direction toward the film side is taken as R(θ), R(θ) is R(0 ) as the maximum, a schematic diagram of the case where R(θ) simply decreases as θ increases. FIG. 11 is a perspective view for explaining the regular reflection angle and the reflectance in a direction deviating from the angle by 20°. Fig. 12 is an enlarged view showing the height information displayed in a hierarchical manner in the range of about 480 μm in the vertical direction and about 640 μm in the horizontal direction of the anti-glare film obtained by Embodiment 1 described later, and the gray scale indicating the height is shown horizontally on the right side. Spend. Fig. 13 is a histogram of the frequency of appearance of each convex or concave region observed on the surface of the anti-glare film obtained by the same embodiment 1 versus the area. FIG. 14 is a histogram showing the vertical axis by frequency×area based on the data in FIG. 13 .

The antiglare film of the present invention will be described with reference to FIG. 1 . This anti-glare film 20 is a film having fine concavo-convex shapes 3 and 4 formed on its surface, and itself is not different from conventionally known anti-glare films. In FIG. 1 , the surface of the average height of the film (referred to as the main plane) is indicated by symbol 1, the projected surface thereof is indicated by symbol 2, and the rectangular coordinates on the film surface are indicated by (x, y). Also, portions (protrusions) 3 that are higher than the plane height are indicated by solid lines, and portions (recesses) 4 that are lower than the average height are indicated by dashed lines.

In the present invention, the area higher than the average height of the unevenness is regarded as a raised area, and the area lower than the average height of the unevenness is regarded as a sunken area, and the area of each raised area or sunken area is calculated, and the specified area is used to mark the area. Calculate the frequency of the raised area or the sunken area, and further calculate the frequency of the apparent area by using the above-mentioned specified area line according to the area × frequency, and use a histogram to represent the apparent area of the raised area or the sunken area. When the frequency of the area is measured, the peak will appear below 300 μm ² , and the half-spectrum amplitude of the peak will reach below 60 μm ² .

In this histogram, the larger the value of the area where the peak occurs, the rougher the bumpy area. Moreover, a raised region or a depressed region having an area of ³⁰⁰ μm is equivalent to a circle with a radius of about 10 μm. At a position larger than 300 μm ² , the phenomenon of bright spots will increase, reducing visibility. When the frequency of the apparent area of the raised region or the recessed region is represented by a histogram, the peak is preferably set to appear at a position below 200 μm ² , further below 150 μm ² , especially at a position below 100 μm ² . Furthermore, when the frequency of the apparent area of the raised region or the recessed region is represented by a histogram, the half-spectrum amplitude of the peak that appears corresponds to the distribution of the apparent area of the raised region or the recessed region per unit area.

Conventional anti-glare films, especially anti-glare films obtained by dispersing fillers, have irregularities in parts where fillers are well dispersed and irregularities in parts where fillers are not well dispersed and aggregated. In this state, if the number of irregularities is simply counted, in general, the number of irregularities with a small area in the well-dispersed portion of the filler is large, and on the other hand, the number of irregularities with a large area caused by the aggregation of the filler Very few. Furthermore, when observed with an optical microscope or a stylus-type film thickness gauge, etc., it is possible to clearly observe a large-area concave-convex shape caused by filler aggregation. With regard to the optical properties of bright spots and the like, it is considered that such a large-area concavo-convex shape plays a large role, and therefore an evaluation method that considers the area of the concavo-convex shape is required. Therefore, in the present invention, the surface structure of the anti-glare film is specified based on the distribution of the apparent area of the protrusions or depressions in consideration of the area of the concave-convex shape.

Hereinafter, regarding the antiglare film of the present invention, the calculation method and significance of the distribution of the apparent area of the convex region or the concave region on the surface will be described. First, in an arbitrary region on the surface of the film, the height of each point constituting the surface of the film is measured, and the average value of the height of the entire measurement region is calculated. Then, the area above the average value is defined as a raised area, and the area below the average value is defined as a depressed area.

In FIG. 2 and FIG. 3, the height distribution of the uneven|corrugated area|region of an anti-glare film is shown. Fig. 2 is a three-dimensional contour map that curves the height of each point on the surface of the film using a certain horizontal resolution scale. Fig. 3 is the average height of each point obtained in Fig. 2, the collection of points higher than the average value is used in white, that is, the raised area described in the present invention is curved, and the point lower than the average value is used in black A collection of , that is, the two-dimensional contour map of the concave region curves described in the present invention. For example, in FIG. 3 , with respect to the raised areas indicated in white, the respective areas are calculated. Since it can be considered here that the protrusions and the depressions are almost symmetrical in their respective height directions, their respective areas can be calculated with respect to either of the protrusions or the depressions. Regardless of whether it is a raised area or a recessed area, it is better to meet the necessary conditions specified in the present invention. Also, instead of calculating the surface area formed by the raised or depressed regions, their projected area is calculated. Moreover, in Fig. 2 and Fig. 3, for the sake of easy understanding, only a few concave-convex areas are shown. In fact, the height of the surface should be calculated in the area containing a plurality of concave-convex to calculate the average value of the overall height of the area. , and calculate the area of multiple convex or concave regions respectively.

FIG. 4 is an example of a power distribution graph (histogram) in which the number of each raised region or depressed region calculated by the above method is plotted using a predetermined area reticle. Since the apparent area is further calculated, the product of the area interval and the frequency is calculated from the obtained frequency value with respect to the predetermined area reticle, and is used as the frequency of the apparent area. FIG. 5 is an example of a power distribution graph (histogram) in which the frequency of the apparent area calculated from the graph in FIG. 4 is plotted using the predetermined area reticle.

It can be seen that in the histogram that curves the number (frequency) of protrusions or depressions relative to the area as shown in Figure 4, there are multiple protrusions or depressions with small areas, and there are many protrusions or depressions with large areas. There are fewer regions, but large raised or depressed regions play a big role in terms of optical performance. Therefore, in the present invention, the apparent area is calculated by multiplying the area by the frequency, and the distribution of the apparent area is calculated from the histogram obtained by graphing it. In this specification, the half-spectrum amplitude (full width that half maximum: also referred to as the half-spectrum full width) of the peak in the histogram having the thus-obtained apparent area is referred to as the distribution of the apparent area. The calculation method of this apparent area distribution will be described in detail below.

The height of the surface of the uneven film can be determined from the three-dimensional shape of the surface roughness measured by a non-contact three-dimensional surface roughness tester, atomic force microscope (Atomic Force Microscope: AFM), laser confocal microscope, etc. calculate. The horizontal resolution required by the detector should be at least below 5 μm, preferably below 2 μm, and the vertical resolution should be at least below 0.1 μm, preferably below 0.01 μm. As a non-contact three-dimensional surface roughness tester suitable for this test, there are products of Zygo Corporation in the United States and the "New View 5000" series that can be purchased from ZAIKO Co., Ltd. in Japan. Although it is better to have a larger detection area, it should be at least 100 μm×100 μm or more, preferably 400 μm×400 μm or more.

Specifically, by using the above-mentioned tester, it is possible to calculate the data corresponding to the heights of the respective x and y coordinates in a lattice shape determined in the horizontal resolution of the tester shown in FIG. 2 . The average value of all height data is calculated, and the area above the average value is regarded as a raised area, and the area below the average value is regarded as a depressed area. The concave-convex shape obtained in this way is transformed into a binary image, and the area of the convex area or the concave area is calculated using image processing software. The image processing software is not particularly limited as long as it can calculate the number of image elements in each convex area or concave area, but in the example shown in FIG. 4 and FIG. The software, using NIH Image, counts the number of image elements in each raised or sunken region portion of the binarized image to calculate the area. NIH Image is an image processing software developed by the NIH (National Institute of Health) in the United States. It is named NIH Image after the name of the development institution.

Then, divide the areas between the maximum area and the minimum area obtained by image processing into 10 to 100 equal parts, and calculate the number of protrusions and depressions between the adjacent areas that meet the division. , to get the frequency. If the division of the area is too fine, the frequency will be discrete, and it is difficult to calculate the distribution; on the contrary, if the division of the area is too large, it is not ideal because only the approximate frequency can be seen. In the example shown in FIG. 4 and FIG. 5 and the embodiment described later, the area is divided into 10 μm ² intervals. That is, in Fig. 4 and Fig. 5 , the area on the horizontal axis is represented at intervals of 10 μm ² , the first division is "0", indicating 0 μm ² or less, the next division represents the area between 0 μm ² and 10 μm ² , and thereafter , for example, the division of the part denoted as "50" represents an area between 40 μm ² and 50 μm ² . The same is true in FIGS. 6 , 10 , and 11 below that show histograms.

Furthermore, in order to obtain the distribution of the apparent area, the product of the average value of each adjacent area and the number (frequency) of protrusions or depressions belonging to the section is calculated as the frequency of the apparent area. For example, if the area is divided at intervals of 10 μm ² and the number of protrusions or depressions between 20 μm ² and 30 μm ² (the median value is 25 μm ² ) is 5, the frequency of the apparent area is 25 μm ² ×5 = 125 μm ² . The frequency of the obtained apparent area is plotted against the area value to create a histogram of the apparent area. Using the half-spectral amplitudes of the peaks of this histogram, the distribution of the apparent area of the concavo-convex shape is defined. The peak in the histogram of "area x frequency" relative to the area means the maximum value of the "area x frequency" in the histogram obtained as described above, that is, in the example of Fig. 5, it is 20 μm Values for area division between ² and 30 μm ² .

Here, a method of calculating the half-spectrum amplitude of the peak in the histogram will be described with reference to FIG. 6 . FIG. 6 is an enlarged view of the histogram in FIG. 5 with respect to the horizontal axis between 0 and 200 μm ² . Furthermore, in the overall detection range, a point where the vertical axis (area×frequency) shows the maximum value is defined as a point P indicating the peak value. Draw a vertical line A from this point P to the horizontal axis, take the intersection point of it and the straight line with the area of the horizontal axis × frequency = 0 as the reference point B, and draw a straight line parallel to the horizontal axis through the point C that bisects the peak line segment PB (ray), take the area interval between the minimum value and the maximum value intersecting the histogram as the half-spectrum amplitude WH. Furthermore, as shown in FIG. 6, when the histogram that begins to fall from the point P that represents the peak rises again before reaching the half value of the peak value, that is, when the histogram reaches the half value of the peak value and then rises again to exceed the half value of the peak value , the histogram will not exceed the half-value of the peak value again, and finally determine the points U and V that exceed the half-value, and use the width between UV to determine the half-spectrum amplitude WH. When determining the half-spectral amplitude WH, the minimum value of the intersection of the ray and the histogram is taken as the minimum value of the area division represented by the column, and the maximum value of the intersection of the ray and the histogram is taken as the maximum value of the area division represented by the column . That is, in the example shown in Fig. 6, since the ray intersects the cylinder representing the area between 10 μm ² and 20 μm ² at the side where the area is small, the value of point U is taken as 10 μm ² , and on the side where the area is large One side ray intersects the cylinder representing the area between 140 μm ² and 150 μm ² at last, and the value of point V is taken as 150 μm ² , so the half-spectrum amplitude WH in this example is 140 μm ² (=150-10).

In the histogram of the area relative to the "area × frequency" obtained above, if the half-spectrum amplitude of the peak is 0, the area of the raised or depressed area will be concentrated at 1 point. On the other hand, if the half-spectrum amplitude becomes large, it means that the distribution of the apparent area of each uneven region is wide (large). The smaller the half-spectrum amplitude is, the narrower (smaller) is the distribution of the apparent areas of the respective concave-convex regions.

When the distribution of the apparent area is wide, the raised or depressed regions with a large apparent area are mixed with the raised or depressed regions with a small apparent area. Although the cause cannot be determined, it can be seen that the bright spots become larger. In addition, when the distribution of the apparent area is narrow, it can be seen that the area of the raised or recessed area is relatively concentrated, and when used in combination with a high-definition display, the number of bright spots decreases. If the distribution of the apparent area, that is, the half-spectrum amplitude of the peak in the histogram representing the frequency of the above-mentioned apparent area exceeds 100 μm ² , the bright spot becomes large and the visibility deteriorates remarkably. On the other hand, if the distribution of the apparent area (peak half-spectrum amplitude) is 60 μm ² or less, almost no bright spots can be observed, and good visibility can be obtained. Therefore, especially in order to improve the visibility in a high-definition display device, it is important to set the distribution of the apparent area (peak half-spectrum amplitude) below 100 μm ² and to set the half-spectrum amplitude below 60 μm ² better. The half-spectrum amplitude of the peak in the frequency histogram representing the apparent area is more preferably 50 μm ² or less. However, if the concave and convex areas are arranged regularly, the interference fringes will become obvious when the half-spectrum amplitude is 0, and this tendency will appear if the half-spectrum amplitude is below 10 μm ² . Therefore, it is preferable that the apparent areas of the raised or depressed regions have a certain degree of distribution, and it is preferable that the above-mentioned half-spectrum amplitude reaches 10 μm ² or more.

In the present invention, the film with a specific surface shape can be produced by any method, for example, it can be produced by pressing a thermoplastic transparent resin film on an embossed mold with a suitable surface shape under heating. The molding method may be a method in which the UV-curable resin-coated surface of the transparent substrate coated with the UV-curable resin is closely bonded to the above-mentioned embossing mold, and then irradiated with ultraviolet rays in this state to cure it.

Examples of methods for producing embossed molds include, for example, a method in which a concave-convex shape formed by photolithography is combined with metal electroforming (plating) thereon is a good method. Specifically, by forming a photoresist film on a base material, finely exposing it to light, and then developing it, a concavo-convex shape is formed on the above-mentioned photoresist film. After metal electroforming is performed on the resist film, the metal is peeled off from the photoresist film to make a metal plate that replicates the concave and convex shapes, that is, an embossed mold. By using this embossing mold, the method of pressing thermoplastic transparent resin on the embossing mold in a heated state, or coating the surface of the ultraviolet curable resin of the transparent base material coated with ultraviolet curable resin The anti-glare film with a predetermined surface shape can be produced by closely bonding with the above-mentioned embossing mold, and irradiating ultraviolet rays in this state to harden the ultraviolet curable resin.

In this way, an example of a method of producing an embossed mold by combining photolithography and electroforming and using the mold to produce an antiglare film will be described with reference to FIG. 7 . First, as shown in FIG. 7(A), a photoresist film 12 is produced on the surface of the substrate 11 on which the photoresist film is formed. The substrate 11 used here can be a material with a flat surface that is properly bonded to the photoresist film, such as inorganic transparent substrates such as glass, quartz, and alumina, or metal substrates such as copper and stainless steel. Moreover, the photoresist coated on the base material 11 may be a material with photosensitivity and appropriate resolution, and the exposed part may be soluble in a developing solution, and a positive photoresist that is removed after development may be used. , or the exposed part is hardened, insoluble in the developer solution, any one of the negative photoresist of the unexposed part is removed by development. For example: nonpolaric resin, acryl resin, styrene and acrylic acid copolymer, polyvinyl phenol, poly(α-methyl vinyl phenol) (Poly (α-methylvinyl phenol)) and other alkaline soluble resins, and photosensitive compounds such as quinonediazido (quinonediazido) group-containing compounds, dissolved in organic solvents to form positive photoresist compositions, or It is a negative photoresist composition prepared by dissolving a photosensitive resin containing an alkaline soluble resin, a photooxygen generator, a crosslinking agent, etc. in an organic solvent. However, it is preferable to use a positive photoresist in order to generate light diffraction at the edge portion by short-distance exposure in the subsequent exposure process, and to form a concave portion including a circle by subsequent development. Referring to FIG. 7 , the example shown below is an example when a positive photoresist is used.

The thickness of the photoresist film 12 formed on the substrate 11 can be appropriately adjusted according to the depth and shape of the unevenness desired to be formed on the surface of the antiglare film. The formed film thickness is equal to the target depth, or slightly thicker is better. As a specific range of the film thickness, it is preferable that the intended depth of the uneven shape is greater than or equal to +5 μm or less.

In order to form the photoresist film 12 on the base material 11, for example, a well-known and appropriate method such as a spin coating method, a dipping method, or a roll coating method can be used. After the coating film is formed, prebaking (preheat) is generally performed in order to remove the solvent contained in the photoresist. The prebaking can be performed at a temperature of about 60 to 120° C. for 0.5 to 10 minutes, for example, using a hot plate, an oven, or the like. The temperature and time of pre-baking can be properly adjusted according to the type of photoresist and the sensitivity required by the photoresist.

With respect to the photoresist film 12 thus formed on the base material 11, fine exposure is then performed as shown in FIG. 7(B). In FIG. 7(B), an example of fine exposure through the photomask 14 of two layers is shown. The two-layer photomask is a photomask with a transmission part and a light-shielding part formed on a substrate made of transparent glass or quartz for the exposure light source, and the transmittance of the light from the exposure light source at the transmission part The transmittance is 100% or close to 100%, and the light from the exposure light source is blocked at the light-shielding part, and the transmittance at the light-shielding part is 0% or close to 0%. Specifically, for the exposure light source, a metal mask of a light-shielding portion is formed on a transparent substrate with metal such as chromium, or an emulsion mask is formed of a light-shielding portion by exposing an emulsion to light.

As shown in FIG. 7(B), the two-layer photomask 14 is arranged with some distance from the surface of the photoresist film 12 to perform short-distance exposure. Proximity exposure means that the photomask 14 is brought close to the photoresist film 12, but is not brought into close contact, but is exposed at a certain distance. By using this two-level photomask 14 for short-distance exposure, light diffraction will occur at the edge of the mask pattern of the photomask 14, so that the imaging of the photomask 14 is blurred, and the light beam 15 passing through the transmission part After the back of the shading part is expanded, a continuous light distribution is produced. Then, according to the light intensity distribution of short-distance exposure, the photoresist film 12 will be exposed to light, and the remaining film thickness of the photoresist will be changed according to the light intensity of irradiation through subsequent development. The surface of the resist film 12 has an uneven shape according to the mask pattern, exposure amount, distance between the photomask and the photoresist film (referred to as "exposure gap" or "close gap"), and the like. In this case, only one type of aperture may be used for the photomask, but it is also effective to manufacture a photomask by combining several types, for example, two or three types of apertures.

7(B) shows an example of fine exposure by short-distance exposure using a two-layer photomask 14. In addition, by using a method of fine exposure through a multi-layer photomask, the exposure light source can be adjusted according to the location. The same effect can also be obtained by finely exposing the spatial light modulation element that produces changes in the intensity of light.

The multi-layer photomask is different from the above-mentioned two-layer photomask, and is a photomask in which the transmittance can be changed in multiple steps or continuously depending on the location. As such a multi-layer photomask, for example, using a high-resolution photomask drawing device such as an electron beam drawing device, according to the wavelength of the exposure light, sufficiently small-sized light-shielding parts and transmitting parts are provided. , and use the area ratio of the light-shielding part to the transmitting part to express the layer, and the mask space where the material whose transmittance changes after being exposed to high-energy beams such as electron beams and laser beams is dispersed on the transparent medium A photomask that continuously changes transmittance by irradiating a high-energy beam to change its intensity depending on the location, and a photomask that forms an emulsion-like substance on a base material, has photosensitivity, and has an optical density according to the amount of irradiated light. A variable substance uses a photomask that changes the light intensity to expose the substance and changes the optical density according to the location.

On the other hand, a spatial light modulation element capable of varying the light intensity of an exposure light source according to a location is an element capable of spatially varying the intensity of light transmitted through the element or light reflected by the element. For example: a light modulating element configured with a multi-pixel arrangement composed of a liquid crystal element or a digital micromirror device (Digital Micromirror Device: DMD). When the liquid crystal element is used as a spatial light modulation element, since the transmittance can be set for each pixel of the liquid crystal element constituting a multi-pixel, by making the light with a spatially uniform intensity distribution emitted from the exposure light source By passing through the liquid crystal element, the intensity distribution of the exposure light conforming to the transmittance of the pixels of the liquid crystal element can be obtained, thereby generating the spatial intensity distribution of the exposure light that can be irradiated on the photoresist film. In addition, when the DMD is used as a spatial light modulation element, the inclination angle of the micromirror can be properly utilized to reflect the light in the direction of the photoresist film and the appropriate change in the reflection in directions other than the photoresist film. , so that by changing the time of reflection toward the photoresist film for each pixel, the actual reflectance per unit time can be changed for each pixel. That is, by using the DMD to reflect the light with a spatially uniform intensity distribution from the exposure light source, the intensity distribution of the exposure light that conforms to the tilt angle time of the micromirror can be obtained, and the exposure light that is irradiated on the photoresist film will be generated. The spatial distribution of the intensity.

As a light source for exposure, a light source that sensitizes the photoresist film 12 can be used, and an appropriate light source is used according to the type of photoresist. For example, a high-pressure mercury lamp or an ultra-high pressure mercury lamp is used as a light source, and near-ultraviolet rays such as g-line, h-line, and i-line emitted therefrom can be used, or a laser having a signal wavelength close to the bright line of these mercury lamps can be used. During exposure, optical components such as lenses and mechanical components such as mask alignment may be provided between the exposure light source and the photoresist film as long as the effects of the present invention are not impaired.

On the photoresist film 12 subjected to fine exposure in this way, a development treatment is then performed to obtain a photoresist film 13 in which concavo-convex shapes are formed as shown in FIG. 7(C). The developing process is, for example, contacting the exposed photoresist film 12 formed on the substrate 11 with a developer suitable for the type. A process of forming a concavo-convex shape on the etchant film 12 . A developing solution can be suitably selected and used from well-known thing according to the kind of photoresist. After the development treatment, it is usually washed with water and then post baked. Through the post-baking, the strength of the remaining photoresist film can be improved, and the bonding property with the substrate 11 can be improved. This post-baking also has the effect of desensitizing the unexposed residual film. The post-baking can be performed at a temperature of about 100 to 200° C. for about 0.5 to 30 minutes, for example, using an oven or a hot plate.

Then, as shown in FIG. 7(D), on the photoresist film 13 in which the concavo-convex shape has been formed, electroform metal 17 to replicate the concavo-convex shape on the surface of the photoresist film 13 on the electroformed Metal 17 on. Metals used for electroforming can be metals that have been used in the field of electroplating, such as nickel, nickel-phosphorus alloy, iron-nickel alloy, chromium, chromium alloy and other metals. The thickness of the metal 17 formed on the photoresist film 13 by electroforming is not particularly limited, but it is preferably about 0.05 to 3 mm in terms of durability. When electroforming is directly performed on the photoresist film 13, the surface of the photoresist film 13 needs to be conductively treated before electroforming. Sputtering (splitting) forms a metal film with a thickness of less than 1 μm, or adopts an electroless plating method. When it is not desired to carry out electroforming directly on the photoresist film 13, for example, instead of replicating the concave shape on the photoresist film 13 on the metal 17 to form a convex shape, When the recessed shape on the photoresist film 13 is replicated to form the recessed shape on the metal 17, for example, the concave-convex shape formed on the photoresist film 13 can be replicated on the resin, and then the concave-convex surface of the resin is as described above. The method of conduction treatment, and then the method of electroforming.

Then, the metal plate 17 after the concave-convex shape replication on the photoresist film 13 having the concave-convex shape is peeled off from the photoresist film 13, or the metal plate 17 formed on the photoresist film 13 After the concave-convex shape is copied on the resin, in the method of electroforming on the resin, the metal plate is peeled off from the resin, as shown in Fig. Flower Casting 18.

Using the obtained embossing mold 18, the concave-convex shape formed on the surface is copied on the film to obtain an anti-glare film. In the example shown in (F) and (G) of FIG. Next, ultraviolet rays are irradiated from the side of the transparent base film 21 to harden the ultraviolet curable resin 22 to obtain an anti-glare film 20 having a concave-convex UV curable resin 22 layer on the transparent base film 21 . Not only limited to this example, as mentioned above, the anti-glare film with unevenness formed on the surface can also be obtained by pressing and molding a thermoplastic transparent resin film on the above-mentioned embossing mold 18 under heating.

As shown in (F) and (G) of FIG. Any commercially available kind is used. For example: polymethylol propanetriacrylate, pentaerythritol tetraacrylate and other multifunctional acrylates (pentaerythritoltetraacrylate) are used alone, or two or more of these substances are used in combination, and "IRUGAKYUA 907", "IRUGAKYUA184" (manufactured by CHIBA SPECIALTY CHEMICALS), "RUSHIRIN TPO" (manufactured by BASF) and other photopolymerization initiators as ultraviolet curable resin.

On the other hand, when adopting the method of molding the concavo-convex shape of the mold 18 on the thermoplastic transparent resin, as the thermoplastic transparent resin film, as long as it is really transparent, any material can be used, for example: polymethylmethacrylate (polymethylmethacrylate) Thermoplastic resins such as polycarbonate, polyethylene terephthalate, triacetylcellulose, and norbornene compounds as monomers, such as amorphous cyclic polyolefins Solvents for making films or laminated films, etc. Using such a transparent resin film also becomes the transparent base film 21 when using the above-described ultraviolet curable resin.

In the present invention, a photomask 14 having at least two patterns of different sizes is used in the photolithography process, particularly in the exposure process shown in FIG. 7(B). The pattern mentioned here refers to each transmissive part (opening) or light-shielding part whose size is at least sufficiently larger than the wavelength of the exposure light. That is, it does not mean that the size is the same as or smaller than the wavelength of the exposure light. A high-resolution photomask drawing device such as an electron beam drawing device is used to provide a transmission part and a light-shielding part that are sufficiently smaller than the wavelength of the exposure light. When the gradation is used as a gradation mask, the transmissive part or the light-shielding part sufficiently smaller than the wavelength of the exposure light is expressed by the area ratio of the transmissive part and the light-shielding part. In the present invention, the diameter of a circle having the same area as the pattern is taken as the size of the pattern.

When two-layer photomasks having patterns of the same size are used, the shapes of the concavities and convexities formed on the photoresist film by the photolithography method have almost the same size. As described above, considering the size of the pixels in an image display device such as a liquid crystal display device or a plasma display, when the pattern sizes formed on the photoresist film are almost the same, even if the concave-convex shape is copied on the photoresist film by electroforming. After copying on the metal plate and then on the film, since the size of the concave and convex shapes on the film is almost the same, the reflected light tends to appear red due to the interference or diffraction between the reflected light and based on the concave and convex shape of the surface.

In the present invention, since photoetching is carried out using photomasks with patterns of different sizes, and the shapes formed on the photoresist film have various sizes, it is difficult to produce the interference between the above-mentioned reflected light and the interference of light. Diffraction, the coloring of reflected light caused by the uneven shape of the surface and the phenomenon that the reflectance of light of a specific wavelength becomes high at a specific angle also rarely appear.

In this photomask, if the size difference of the pattern is too small, the size of the unevenness formed on the surface of the photoresist film will be almost the same, and it is difficult to fully bring out the desired effect of the present invention. On the other hand, if the pattern If the size difference is too large, the density of the patterned portion and the non-patterned portion on the photomask is too large, and it may be difficult to achieve uniform anti-glare performance. Therefore, regarding the size of the pattern formed on the photomask, the ratio of the maximum size (diameter) to the minimum size (diameter) is preferably 1.1 times or more and 2 times or less. The size ratio of the pattern is preferably not less than 1.2 times and not more than 1.5 times, more preferably not more than 1.3 times. According to the display device for which the anti-glare film is applied, the diameter of each pattern is preferably in the range of 1-50 μm, more preferably not less than 5 μm and not more than 30 μm.

Regarding the total area of the respective patterns with different sizes on the photomask, it is preferable that the difference between the respective patterns is not too large. That is, for example, when pattern X of a certain size is mixed with pattern Y of another size, the ratio of the total area of pattern X to the total area of pattern Y is preferably in the range of about 0.7 to 1.3. When three patterns of different sizes are mixed together, any two of them may meet this relationship, and it is better if all patterns of different sizes meet this relationship.

As shown in FIG. 7(B), it is preferable to arrange two layers of photomasks 14 at a constant distance from the surface of the photoresist film 12 for short-distance exposure. Proximity exposure means that although the photomask 14 and the photoresist film 12 are brought close to each other, they are not tightly bonded, but are exposed at a constant interval. By using this two-level photomask 14 for short-distance exposure, as shown in FIG. It will be blurred, and the light beam 15 passing through the transmission part will expand through the back of the light-shielding part to produce a continuous light distribution. Then, the photoresist film 12 is exposed to light according to the distribution of the amount of light exposed at a short distance, and the remaining film thickness of the photoresist corresponding to the light amount distribution will change through the subsequent development process. The surface of the resist film 12 is formed in a concavo-convex shape according to the mask pattern, exposure amount, distance between the photomask and the photoresist film (called "exposure gap" or "close distance gap"), etc. .

When using the above-mentioned two-layer photomask for close-range exposure, the distance between the photomask and the photoresist film is set to L (μm), and the average diameter of the pattern of the photomask is set to It is D (μm), and it is preferable to perform exposure under the condition that the value of L/D ² is 1.3 to 2.8, that is, the condition that satisfies the following formula (1).

1.3≤L/D ² ≤2.8 (1)

The relationship between the interval L between the photomask and the photoresist film and the average diameter D of the pattern of the photomask is explained based on FIG. 8 showing a part of FIG. 7(B) enlarged. As shown in the figure, the interval between the photomask 14 and the surface of the photoresist film 12 is set to L. In the present invention, since a photomask having at least two patterns of different sizes is used, for example, if the photomask 14 has three patterns, the diameters of the respective patterns are set to _D1 , _D2, and _D3 . The average diameter D of the patterns is a weighted average obtained by weighting the sizes of these different types of patterns and the number of patterns. When there are three kinds of patterns with _D1 , _D2 and _D3 diameters shown in Fig. 8, the number of each pattern in the whole or unit area of the photomask is respectively _N1 , _N2 and _N3 , then the average diameter D can be calculated using the following formula (2).

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="C20041008715000451.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="C20041008715000451.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="N"\; filenames="C20041008715000451.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="C20041008715000451.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The image diffusion of the light transmitted through the fine opening is generated according to the index (L/D ² ·λ) composed of the distance L between the opening and the photoresist film, the size D of the opening part, and the wavelength λ of the light Change, when the interval between the opening and the photoresist film is small, the shape of the opening is almost directly copied on the photoresist film, and as the interval between the opening and the photoresist film becomes larger, the The photoresist film is irradiated with diffused light centered on the optical axis. Therefore, if the value of L/ ^D2 is too small, the exposure image formed on the photoresist film will be reflected on the pattern of the opening part of the photomask, and the distribution of energy will change rapidly according to the shape of the opening, so it is easy to Formation of through-holes in the photoresist film degrades the light-scattering function of the antiglare film obtained later. On the other hand, if the value of L/D ² is too large, the light diffracted by the photomask will diffuse, making it difficult to form a pattern on the surface of the photoresist film. According to experiments, it can be confirmed that when the value of L/D ² is in the range of 1.3 to 2.8, a generally good exposure image can be formed.

Moreover, in the above description, according to (A)-(E) of FIG. 7 , the thin film of concave-convex shape formed by implementing fine exposure and development on the photoresist film 12 is used as an original plate, and finally it can be made into a thin film on the thin film. The anti-glare film 20 with concave-convex shape continuously copied on it. Therefore, in order to manufacture the original photomask 14, it is necessary to set a masking pattern designed to obtain the shape specified in the present invention. Designing such a masking pattern on the entire photomask 14 is a very cumbersome operation. Because the data capacity of the masking pattern is very large, the burden on the mask plotter is also very large. Although it is feasible in principle, it may not be used. in reality. Therefore, using a masking pattern composed of unit cells with a fixed area is designed, a plurality of unit cells are arranged, and translational symmetry is maintained, and a photomask that can cover the entire photoresist film 12 is used. is advantageous. By adopting such a method, it is possible to reduce the trouble of designing the shielding pattern of the entire photomask 14, which is also advantageous from an industrial point of view. The translational symmetry here means that the above-mentioned unit elements are arranged in a certain direction such as front, back, left, and right, or obliquely. As an example of arranging a masking pattern and maintaining its translational symmetry state, it can be cited that the coordinates of the center of gravity of each unit element are arranged in a square lattice shape, a rectangular lattice shape, a rhombus lattice shape, a hexagonal lattice shape, etc. lattice-like state.

In the photomask having at least two types of patterns with different sizes, at least two types of patterns are required, and the upper limit of the number of types is not particularly limited. It's just that the more types of patterns, the larger the data capacity when designing masking patterns. Therefore, in terms of practicality, it is preferable that the type of pattern can be appropriately selected from one of two, three, four, and five types according to the intended performance.

As described above, the embossed mold 18, which is a metal plate formed with concave and convex shapes, is wound on a roll, or the embossed mold 18 is arranged on the surface of a plurality of rolls and rolled up as needed to make a surface. An embossing roll having a concave-convex shape, using this embossing roll, is suitable as a method of continuously replicating the concave-convex shape on the surface of a film. According to this method, uneven shapes can be continuously and efficiently copied on a large-area film, which has high productivity.

As described above, exposure is carried out through a photomask having at least two patterns of different sizes, a concave-convex shape is formed by developing a photolithography method, and a metal is electroformed on the surface to make a mold, and the mold is used on the thin film. The method of replicating the concave-convex shape on the surface can produce an anti-glare film with fine concave-convex shape formed on the surface, good anti-glare performance and excellent optical performance. At this time, the anti-glare performance and optical performance can be controlled by appropriately selecting conditions such as the pattern of the photomask, the exposure amount, and the exposure gap.

In the present invention, since the use of photolithography to produce concave-convex shapes is used in combination with electroforming metal on its surface to produce a mold with fine concave-convex shapes, and use the mold to replicate the concave-convex shapes on the surface of the film. , it is possible to manufacture an anti-glare film that can display a uniform distribution of concavo-convex shapes that affect the anti-glare performance, and can display high performance, and has good productivity. Specifically, for example: set the reflectance (regular reflectance) of the light incident in the regular reflection direction from the normal direction of the anti-glare film at any angle of 5 to 30° as R(0), and When the reflectance of incident light at an angle θ in which the reflection direction is inclined toward the anti-glare film side is set as R(θ), a simple decrease in the reflection curve that curves the θ dependence of R(θ) can be easily obtained film.

The concept of the reflection curve detection is shown in FIG. 9 . That is, the regular reflection direction means that when the light 30 is incident from the angle ψ to the normal direction 25 of the anti-glare film 20, in the plane 26 containing the normal 25 and the direction 30 of the incident light, the direction from the angle ψ to the direction of the incident light The opposite direction of 30 reflects the direction of light 32 . ψ is the angle of incidence and also the angle of positive reflection. Strictly speaking, the sign is a plus or minus sign. The reflectance for the regular reflection direction 32 of the incident ray from the incident ray 30 is a regular reflectance R(0). And, when the incident angle ψ is arbitrarily set between 5° and 30°, in the plane 26 including the film normal direction 25 and the incident light direction 30, the anti-glare film 20 is directed from the regular reflection direction 32 In the direction 34 in which only one side is inclined by the angle θ, the reflectance with respect to the incident light is detected, and this is taken as R(θ). Change the inclination angle θ from 0° (that is, the direction of regular reflection) to 90°-ψ (that is, the direction parallel to the film surface), measure the reflectivity R(θ) of each inclination angle θ, and curve it , generally R(θ) when θ=0°, that is, R(0) is the largest. According to the method of the present invention, in the graph of the reflectance R(θ) with respect to the inclination angle θ, a thin film having a curve in which the θ dependence of R(θ) simply decreases as shown in FIG. 10 can be easily obtained.

The bright spot of the anti-glare film can be evaluated by installing the anti-glare film on a high-definition liquid crystal panel (panel), irradiating the liquid crystal panel and the anti-glare film with light from the background (backlight), and visually inspecting the surface of the panel. In order to evaluate bright spots, it is better to use a liquid crystal panel with higher fineness, and it is easier to find bright spots. As for the fineness of the panel, it is better when it is above 150ppi (pixel per inch), and it is better when it is above 170ppi.

The reflectance of the antiglare film of the present invention for the direction deviating from the regular reflection angle of 20° is preferably 0.001% or less. In FIG. 9, the inclination angle θ is 20°, and the direction 9 deviates from the regular reflection direction 8 by 20°. The direction 9 that deviates from the regular reflection angle of 20° appears in a conical shape centered on the regular reflection direction 8, and the reflectance for the direction that deviates from the regular reflection angle of 20° is expressed in the above-mentioned normal 5 In the plane 7 of the incident light direction 6, the reflectance of the direction deviated 20° to the film side.

Furthermore, it is preferable that the 45° reflection visibility of the anti-glare film is 50% or less when measured using an optical comb with a width of 1.0 mm between the dark area and the bright area. 45°reflection visibility is measured in accordance with the detection method of imaging visibility in the reflection method specified in JIS K7105. The incident direction and reflection direction of the light to the test piece during the test shall be 45° in accordance with JIS regulations. As stipulated in this JIS, as an optical comb, the ratio of the width of the dark part to the bright part is 1:1, and its width is 0.125mm, 0.5mm, 1.0mm and 2.0mm, which are specified in the scope of this specification and claims. The 45° reflection visibility is the value obtained by using an optical comb with a width of 1.0 mm in the dark and bright areas.

The anti-glare film preferably has a total of 200% or more of the transmitted visibility measured using four kinds of optical combs with widths of 0.125mm, 0.5mm, 1.0mm and 2.0mm in the dark part and the bright part. Transmission visibility can be measured in accordance with the detection method of imaging visibility specified in the transmission method specified in JIS K 7105. According to this JIS, the direction of incident light on the test piece is the vertical direction. In this case, the above-mentioned four types of optical combs are used to detect the imaging visibility specified in the transmission method, respectively, and the total value of these is taken as the total value of the above-mentioned transmission visibility.

Furthermore, the diffusion ratio of the antiglare film of the present invention is preferably 15% or less. The diffuse value can be calculated according to the method specified in JIS K 7105. The diffuse value is a value represented by (diffuse transmittance/all light transmittance)×100(%). In the anti-glare film of the present invention, although the diffusion ratio measured by this method is generally below 20%, it is better if the diffusion ratio is below 15%, and more preferably 10%. If the diffusion ratio value is too high, when this anti-glare film is applied to a display device, especially a liquid crystal display device, in terms of the viewing angle performance of the liquid crystal display device, due to the observation of a direction inclined from its normal, especially a 60° tilt The low-contrast light rays emitted from the above directions are scattered in the front, resulting in a decrease in contrast when viewed from the front.

Since the antiglare film of the present invention composed of the above has excellent antiglare effect, it has improved the bright spots that occur when it is used in combination with a high-definition panel, so after being installed on an image display device, its visual recognition is excellent. Sex is pretty good. When the image display device is a liquid crystal display, the antiglare film can be used as a polarizing film. That is, the polarizing film is mostly a film in which a protective film is laminated on at least one side of a polarizer made of a polyvinyl alcohol (polyvinyl alcohol) resin film that has directionally adsorbed iodine or a dichroic dye. , Paste the anti-glare film with the above-mentioned uneven shape, that is, a polarizing film with anti-glare properties. Moreover, if the above-mentioned concave-convex shaped optical film having antiglare properties is used as a protective film and antiglare layer, and the concave and convex surface is placed on the outside and attached to one side of a polarizer, an antiglare polarizing film can also be obtained. On the polarizing film laminated with a protective film, the above-mentioned anti-glare unevenness can be formed on the surface of the protective film on one side to produce an anti-glare polarizing film.

The image display device of the present invention is a device in which the anti-glare film having the above-described specific surface shape is disposed on the image display means. Here, the representative of the image display means is a liquid crystal panel with a liquid crystal element sealed between the upper and lower substrates, and the orientation state of the liquid crystal is changed by applying a voltage to display an image. Other examples include: plasma display, Electroluminescent (EL) or Organic Light Emitting Diode (O-LED) displays, Cathode Ray Tube (CRT) displays, etc. Furthermore, an image display device can also be constituted by arranging the above-mentioned anti-glare film on the display side of the image display means. In this case, the concave-convex surface of the anti-glare film is made to be the outer side (viewing side). Either the anti-glare film can be directly pasted on the surface of the image display means, or when a liquid crystal panel is used as the image display means, for example, a polarizing film can be pasted on the surface of the liquid crystal panel as described above. The image display device equipped with the anti-glare film of the present invention can use the concave-convex shape on the surface of the anti-glare film to scatter incident light and blur the reflected image, thereby having excellent visibility.

Implementation form

Hereinafter, the present invention will be described in more detail based on the embodiments, but the present invention is not limited to the following embodiments. In these embodiments, unless otherwise indicated, % indicating the content and usage-amount are by weight. In addition, the evaluation and measurement methods of the anti-glare film in the following embodiments are as follows.

(Measurement of surface shape and calculation of apparent area of raised or depressed areas)

Using a non-contact three-dimensional surface shape and roughness tester "New View 5010" (manufactured by Zygo Corporation), the surface shape was measured in an area of about 480 μm×640 μm of the antiglare film. The horizontal resolution of the detector is 1.18 μm, and the vertical resolution is 0.1 μm. Calculate the average value of all the height data, and use the image processing software "NIH image" to transform the area (protrusion) above the average height and the area (concave) below the average height into a binary image to find out the The area of the raised or lowered area. The obtained area data were divided by a 10 μm ² line, and the frequency (number) per 10 μm ² was obtained. Then, the above-mentioned frequencies were multiplied by the average area of the 10 μm ² reticle, respectively, to obtain the frequency per 10 μm ² of the apparent area. The frequency of the obtained apparent area was plotted against the area value, and a graph (histogram) of degree distribution of the apparent area was prepared. From this histogram, the half-spectral amplitude of the peak, that is, the distribution of the apparent area is obtained.

(Measurement of reflectance of anti-glare film)

On the concave-convex surface of the anti-glare film, the light of the parallelized iodine tungsten lamp light source is irradiated concentratedly from the direction inclined 30° to the main normal of the film. The angular variation of the in-plane reflectivity of the direction. For the measurement of the reflectance, "329203 optical power sensor" and "3292 optical power meter" manufactured by Yokogawa Electric Co., Ltd. were used.

(Measurement of Diffuse Ratio)

Measured in accordance with JIS K 7105. In order to prevent the deformation of the sample, an optically transparent adhesive was used, and the concave-convex surface was used as a surface, and it was pasted on a glass substrate to provide measurement.

(Determination of reflection visibility and transmission visibility)

Measured in accordance with JIS K 7105. When measuring the transmitted visibility, in order to prevent the deformation of the sample, an optical transparent adhesive is used to stick it on the glass substrate to provide measurement. In the measurement of reflection visibility, as in the measurement of transmission visibility, a sample bonded to glass is used, but in order to prevent reflection from the glass surface, the glass surface of the glass plate on which the anti-glare film is pasted is tightly pasted with water. A black polymethylmethacrylate (polymethylmethacrylate) plate with a diameter of 2 mm is used to measure light from the sample (anti-glare film) side in this state.

Embodiment 1

In the area of 10mm×10mm, a unit element is designed, and a total of 512,820 random openings with diameters of 8μm, 9μm and 10μm are arranged in the unit element. The average value of the shortest distance was 12.0 μm. A two-level photomask was prepared in which the unit cells were arranged at a period of 10 mm over an entire area of 100 mm×100 mm on a 6-inch square (approximately 152 mm square) quartz substrate.

On the other hand, on a glass substrate of 100 mm × 100 mm, a positive photoresist mixed with a black pigment, which is "P70BK" manufactured by Tokyo Ohka Kogyo Co., Ltd. The thickness after baking reaches about 1.1 μm. The thus obtained glass substrate with photoresist film was placed on a hot plate set at 85° C. for 120 seconds to be prebaked. The photomask produced above was placed on this photoresist film so that the exposure gap was 120 μm, and the g-line, h-line, and i-line emitted from the ultra-high pressure mercury lamp as the exposure light source were irradiated through the photomask. A light (multi-line) is used to achieve 240mJ/cm ² in terms of g-line conversion, and close-range exposure is performed. The exposed glass substrate with a photoresist film was developed in a 0.5% aqueous sodium hydroxide solution at 23° C., and then washed with pure water. Then, it was placed in an oven heated to 180° C. and heated for 20 minutes (post-baking), and a resin layer with many depressions formed on the surface was obtained.

A nickel plating film was formed on the obtained resin layer with depressions by vapor deposition to conduct conductive treatment on the surface of the resin layer. Then, a nickel plating film with a thickness of about 0.3 mm was formed by electroforming on the conductively treated surface. In the state where the nickel plating film is attached to the resin layer with depressions, the inner surface of the nickel plating film is ground, and then further ground to a thickness of 0.15 mm, and the polished nickel plating film is peeled off from the resin layer with depressions to produce It becomes a nickel plate with many bumps on the surface.

In addition, an ultraviolet curable resin "GRANIC PC806T2" manufactured by INK Chemical Industry Co., Ltd. was dissolved in ethyl acetate to a concentration of 50% to prepare a coating liquid. The coating liquid was coated on a triacetylcellulose film so that the thickness of the dried coating film was about 5 μm, and dried in an oven at 60° C. for 3 minutes. Next, press the convex surface of the nickel plate with protrusions produced above on a rubber roller, bring it into contact with the coated surface of the ultraviolet curable resin, and irradiate light such as electroless ultraviolet rays from the side of the triacetyl cellulose film, The amount of light in terms of h-rays was adjusted to 100 ml/cm ² , and the above-mentioned ultraviolet curable resin was cured. The triacetyl cellulose film was peeled from the cured resin and the nickel plate to obtain a transparent anti-glare film composed of a laminate of the cured resin and the triacetyl cellulose film having irregularities on the surface.

The surface shape of this antiglare film was measured in an area of about 480 μm×640 μm using the above-mentioned non-contact three-dimensional surface shape and roughness measuring instrument “New View 5010” manufactured by Zygo Corporation. The data shown in FIG. 12 was obtained by hierarchically transforming and displaying the height information of the anti-glare film. Furthermore, according to the height information, the area of the depression is calculated by the above-mentioned method, and the histogram of the area of the depression shown in FIG. 13 is obtained. At this time, the maximum value of the observed depression area was about 584 μm ² , and the minimum value was about 5 μm ² , and the area interval (reticle) when the histogram was created was 10 μm ² . Then, the frequency×area is calculated according to the above-mentioned method, and the histogram of the apparent area shown in FIG. 14 is obtained. In this histogram, a peak (maximum value) is observed in the interval between 40 μm ² and 50 μm ² . The half-spectral amplitude of the peak was calculated from the histogram of the apparent area shown in Fig. 14, and 30 μm ² was obtained, which is less than 100 μm ² . Therefore, the distribution of the apparent area of the concavo-convex shape on this film is small.

The obtained anti-glare film was placed on a 200ppi high-definition liquid crystal panel, illuminated from behind with a backlight, and the bright spots were visually evaluated, but no bright spots were observed. The anti-glare film had a reflectance of 0.92% in the direction of regular reflection, and a reflectance of 0.00025% in a direction deviated from the angle of regular reflection to the film side by 20°.

Attach the triacetyl cellulose side of this anti-glare film to glass, and measure the diffusion ratio, and measure the reflection visibility at 45° incidence using an optical comb with a width of 1.0mm in the dark and bright areas. As a result, the diffusion ratio was 8.0%, and the reflection visibility was 44.5%, and it was confirmed that it has a low diffusion ratio and the ability to prevent high reflection. Moreover, for the anti-glare film attached to the glass in the same state, the results of the transmission visibility were detected by using an optical comb with a width of 0.125mm, 0.5mm, 1.0mm and 2.0mm in the dark part and bright part, and the following values were obtained respectively, The total value of these four kinds of transmission visibility is 297.4%, and high visibility can be confirmed.

0.125 mm optical comb: transmission visibility 70.5%

0.5 mm optical comb: transmission visibility 75.0%

1.0 mm optical comb: transmission visibility 75.6%

2.0 mm optical comb: transmission visibility 76.3%

             

Total 297.4%

The above-mentioned evaluation and measurement data in Embodiment 1 are summarized in Table 1

Implementation form 2

In an area of 10mm×10mm, except for using a random arrangement of 588,069 circular openings with diameters of 8μm, 9μm, and 10μm, the average value of the shortest distance between the center coordinates of each opening is 11.6μm The anti-glare film was produced in the same manner as in Embodiment 1 except that the unit cells were arranged at a period of 10 mm in the photomask in the entire area of 100 mm×100 mm. As a result of evaluating the distribution of the apparent area of the depressions formed on the surface of the obtained film, the peak (maximum value) of "area" x "frequency" was observed in the interval between 60 μm ² and 70 μm ² , and half of the peak value The spectral amplitude is 30 μm ² . Furthermore, as a result of visual evaluation of bright spots by the same method as in Embodiment 1, no bright spots were observed. Moreover, other optical properties of this anti-glare film are shown in Table 1.

Compare Form 1

As a result of evaluating the apparent area distribution of the protrusions formed on the surface of the antiglare film "AG6" sold by Sumitomo Chemical Co., Ltd. in the same manner as in Embodiment 1, the area between 20 μm ² and 30 μm ² was evaluated. A peak was observed in the interval, and the half-spectrum amplitude of the peak was 140 μm ² . Further, bright spots were visually evaluated by the same method as in Embodiment 1, and bright spots were observed. Other optical properties of the antiglare film are shown in Table 1.

Compare Form 2

As a result of evaluating the apparent area distribution of the protrusions formed on the surface of the antiglare film "GH5" sold by Sumitomo Chemical Co., Ltd. in the same manner as in Embodiment 1, the distribution of the apparent area between 10 μm ² and 20 μm ² was evaluated. A peak is observed in the interval, and the half-spectrum amplitude of the peak is greater than 300 μm ² . The bright spots were further visually evaluated, and as a result, bright spots were observed. Other optical properties of the antiglare film are shown in Table 1.

Table 1

Remarks) Transmission visibility is the total value of 4 types.

Implementation form 3

In a 10mm×10mm square area, a unit element is designed. In this unit element, 233,624, 196,085, and 158,627 circular openings with diameters of 8 μm, 9 μm, and 10 μm are respectively arranged. The nearest opening center The average value of the distance between coordinates is 15 μm. A two-level photomask was prepared in which the unit elements were arranged in a square lattice shape at a period of 10 mm over an entire area of 100 mm x 100 mm on a 6-inch square (approximately 152 mm square) quartz substrate. According to the above formula (2), the average diameter of the openings in the photomask was calculated to be 8.9 μm.

On the other hand, on a 100mm×100mm square glass substrate, a positive photoresist mixed with a black pigment was spin-coated “P70BK” (trade name) manufactured by Tokyo Ohka Kogyo Co., Ltd. And make it about 1.1 μm in thickness after prebaking. The obtained glass substrate with photoresist film was placed on a hot plate heated to 85° C. for 120 seconds to perform prebaking. The above-mentioned photomask was placed on this photoresist film, and the exposure gap was set to 120 μm. Through a photomask, a plurality of g-lines, h-lines, and i-lines emitted from an ultra-high-pressure mercury lamp as an exposure light source are irradiated to achieve an exposure light amount of 240mJ/ ^cm2 in terms of g-line conversion for close-range exposure. The relationship L/D ² between the exposure distance L at this time and the average diameter of the opening was calculated to be 1.51. The exposed glass substrate with a photoresist film was immersed in a 0.5% potassium hydroxide aqueous solution at 23° C. for 80 seconds to develop, and then washed with pure water. Then, it was placed in an oven heated to 180° C. for 20 minutes and post-baked to obtain a photoresist layer with concavo-convex shapes formed on the surface.

A nickel plating film was formed on the concave-convex surface of the obtained photoresist layer with concave-convex shape by vapor deposition to conduct conductive treatment on the surface of the photoresist layer. Then, a nickel plating film with a thickness of about 0.3 mm was formed by electroforming on the conductively treated surface. In the state where the nickel plating film is attached to the concave-convex surface of the photoresist layer, the inner surface of the nickel plating film is ground, and then further ground to a thickness of 0.2 mm, and the polished nickel plating film is removed from the photoresist The layer is peeled off to make a nickel plate with multiple unevenness on the surface.

In addition, an ultraviolet curable resin composition "Grandic 806T" (trade name) manufactured by Dainippon Ink Chemical Co., Ltd. was dissolved in ethyl acetate to prepare a coating liquid having a concentration of 50%. This coating liquid was coated on a triacetyl cellulose (TAC) film having a thickness of 80 μm to a thickness of 5 μm after drying, and dried in a drier set at 60° C. for 3 minutes. Then, use a rubber roller to press the dried film on the concave-convex surface of the above-mentioned nickel plate with a concave-convex shape, so that the photocurable resin composition layer becomes one side of the nickel plate. In this state, from the side of the TAC film The photocurable resin composition layer was cured by laterally irradiating light with an intensity of 20 mW/cm ² emitted from a high-pressure mercury lamp so that the amount of light in terms of h-line became 200 mJ/cm ² . Then, the TAC film was peeled off from the cured resin and the nickel plate to obtain a transparent anti-glare film composed of a laminate of the cured resin and the TAC film having irregularities on the surface.

When the reflected light by the obtained anti-glare film was visually observed, no bright spot of reflected light was found.

Possibility of use in industry

The antiglare film of the present invention is particularly useful for improving the visibility of image display devices including liquid crystal display devices.

According to the anti-glare film manufactured by the above-mentioned method, by arbitrarily controlling the size and shape of the pattern in the photomask using the photoetching method, and controlling the exposure conditions at that time, it becomes a kind of anti-glare film that can have a uniform quality and a large area although it is a large area. Film with excellent anti-glare performance and optical performance. Therefore, this antiglare film is useful for improving the antiglare performance of various display devices including liquid crystal display devices.

Claims (15)

1. a kind of antiglare film, it is characterized in that on its surface has formed fine concavo-convex shape, the region higher than the average height of concavo-convex shape is a convex region, the region lower than the average height of concavo-convex shape is a concave region, find Obtain the projected area of each raised area or the projected area of the sunken area, use the specified area reticle to obtain the frequency of the raised area or the sunken area, and further calculate according to the area × frequency using the above-mentioned prescribed area reticle When the frequency of the apparent area is shown and the frequency of the area of the raised area or the sunken area is represented by a histogram, the peak appears at a position below 300 μm ² , and the half-spectrum amplitude of the peak is below 60 μm ² . 2. The anti-glare film according to claim 1, characterized in that: the peak appears at a position below 150 μm ² . 3. The anti-glare film according to claim 1 or 2, characterized in that: the half-spectrum amplitude width of the peak is greater than 10 μm ² . 4. The anti-glare film according to any one of claims 1 or 2, characterized in that its reflectance in the direction deviating from the regular reflection angle by 20° is less than 0.001%. 5. The anti-glare film according to claim 1, wherein the 45° reflection visibility detected by using an optical comb with a width of 1.0 mm between the dark part and the bright part is 50% or less. 6. The anti-glare film according to claim 1 or 5, characterized in that: the sum of the transmission visibility measured by four kinds of optical combs with a width of 0.125mm, 0.5mm, 1.0mm and 2.0mm in the dark part and the bright part The value is 200% or more. 7. The anti-glare film according to any one of claims 1, 2 or 5, characterized in that: the diffusion ratio is below 15%. 8. An image display device, comprising the anti-glare film according to claim 1 and image display means, wherein the anti-glare film is disposed on the viewing side of the image display means. 9. A method for manufacturing an anti-glare film with a concave-convex shape on the surface, comprising: A photoetching process for forming concavo-convex shapes on a photoresist film formed on a base material by a photoetching method, Electroforming of metal on the uneven surface of the obtained photoresist film, copying the uneven shape on the metal, and peeling off the metal plate on which the uneven shape has been copied from the photoresist film to make a mold for making an electroforming mold , Using this metal plate with the concave-convex shape copied as a mold, the concave-convex film production process that replicates the concave-convex shape on the surface to the surface of the film, Its characteristics are: In the photolithography process described above, the photoresist film is exposed through a photomask having at least two patterns of different sizes, and then developed to produce an antiglare film. 10. The method according to claim 9, wherein patterns are formed on the photomask, and the diameter of the largest pattern in the pattern is 1.1 to 2 times the diameter of the smallest pattern. 11. The method according to claim 9 or 10, characterized in that: a pattern is formed on the photomask, and the ratio of the total areas occupied by at least two patterns of different sizes in the pattern is in the range of 0.7 to 1.3 . 12. The method as claimed in claim 9 or 10, characterized in that: the exposure by the photomask utilizes close-range exposure in which a photomask is arranged at a position spaced from the surface of the photoresist film And carried out. 13. The method as claimed in claim 12, characterized in that: the interval between the photomask and the photoresist film surface is set as L μm, and the average diameter of the pattern of the photomask is set as D μm , exposure is performed under the condition that the value of L/D ² is not less than 1.3 and not more than 2.8. 14. The method according to any one of claims 9, 10, 13, characterized in that: the photomask is composed of a plurality of unit elements with a specified area arranged in order to maintain the symmetry of translation. 15. The method as claimed in claim 9, characterized in that: rolling the metal plate on which the concave-convex shape has been reproduced is rolled on the surface of the drum for the concave-convex film manufacturing process.

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