JP2005140890A - Anti-glare film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-glare film for achieving reduction in irregularities of a screen, without sacrificing glare-shielding property, and to provide an image display device superior in visibility, using it. <P>SOLUTION: In the anti-glare film having minute irregularities on its surface, a region higher than an average height of the irregularities is a projection, a region lower than the average height of the irregularities is a recess, and an individual projection projected area or recess projected area is found. The frequency of the projections or the recesses are found by prescribed are units, and further, the frequency of apparent areas are calculated in the prescribed area units according to (area × frequency). When the frequency of the apparent area of the obtained projection or recess is expressed by a histogram, the anti-glare film 20 is provided in that a peak value appears at a position of 300 μm<SP>2</SP>or smaller, and the half-value width of the peak is 60 μm<SP>2</SP>or smaller. The anti-glare film 20 is arranged at the visible side of an image display means, such as a liquid crystal panel and the image display device is constituted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antiglare film that is suitably used for optical applications such as a polarizing film in an image display device. In particular, even when applied to an image display device with high definition, glare is hardly generated, and high visibility is achieved. It is related with the anti-glare film which can ensure property. The present invention also relates to an image display device using such an antiglare film.

  In an image display device such as a liquid crystal display device, when external light is reflected on the image display surface, the visibility is remarkably impaired. Reflective liquid crystal display devices such as TVs and personal computers that emphasize image quality, video cameras and digital cameras that are used outdoors with strong external light, and mobile phones that display using reflected light In such applications, the surface of the display device is generally treated to prevent such reflection. Reflection prevention processing is broadly divided into antireflection processing using interference by an optical multilayer film and so-called anti-glare processing that scatters incident light by forming fine irregularities on the surface and blurs the reflection image. . The former non-reflective treatment has a problem of high cost because it is necessary to form a multilayer film having a uniform optical film thickness. On the other hand, since the latter anti-glare process can be realized at a relatively low cost, it is used for applications such as large personal computers and monitors.

For example, an anti-glare film can be coated with a UV curable resin with a filler dispersed on a transparent substrate, dried, and then irradiated with UV to cure the resin, forming random irregularities on the film surface. It is manufactured by the method of doing. In the past, many proposals have been made to impart antiglare properties by forming fine irregularities on the surface of a film used in an image display device. For example, Japanese Patent Laid-Open No. 2003-4903 (Patent Document 1) discloses an antiglare film having an antiglare layer on a transparent support and having concave and convex surfaces, and each concave cut surface. An anti-glare film having an area of 1,000 μm ² or less is disclosed. Here, an ultraviolet curable resin in which particles having an average particle size of 0.2 to 10 μm are dispersed is applied onto a transparent support, and ultraviolet rays are applied. By curing, an antiglare film having the above irregularities is produced.

  Japanese Patent Laid-Open No. 2002-365410 (Patent Document 2) discloses an optical film having fine irregularities formed on the surface, and a light beam is applied to the surface of the film from a direction of −10 ° with respect to the normal line. An antiglare film is disclosed in which the profile of reflected light when incident and only the reflected light from the surface is observed satisfies a specific relationship.

Japanese Patent Laid-Open No. 2003-177207 (Patent Document 3) is based on the premise that a multilayer antireflection layer is provided on the uneven surface, but the average height (Rc) of the contour curve element is 0.1 to 0.1. An antireflection film having a resin layer in which an uneven surface of 30 μm is formed and the number of protrusions per 0.01 mm ^{2 of} the uneven surface is 1 to 1000, and the antireflection film surface of the uneven surface An antireflection film is disclosed in which a parallel surface having an inclination angle of 0 to 5 ° occupies 15 to 100%, and 15 to 100% of the parallel surface is formed on a convex portion. In Patent Document 3, a mat shaped film is used to form such irregularities, but a specific method for producing the mat shaped film is not shown.

JP 2003-4903 A JP 2002-365410 A JP 2003-177207 A

  In a conventionally known anti-glare film, particularly an anti-glare film obtained by dispersing a filler, the filler is randomly arranged at the time of coating, so the density distribution of the filler, and hence the density of irregularities formed on the surface. Distribution occurred. When such a conventional anti-glare film is used in combination with a high-definition liquid crystal panel, although the cause is not clear, the display is glaring and it is difficult to obtain sufficient visibility. In order to reduce the uneven density distribution, the blending amount of the filler may be reduced. In this case, however, sufficient antiglare property cannot be obtained. On the other hand, if the blending amount of the filler is too large, the antiglare property is reduced. However, there is a problem that haze increases and contrast decreases.

  This invention is made | formed in view of such the present condition, The objective is to provide the glare-proof film which implement | achieved reduction of the glare of a screen, without sacrificing anti-glare property. Another object of the present invention is to provide an image display device that uses such an antiglare film and has no screen glare and excellent visibility.

  As a result of diligent research under such a purpose, the present inventors have clarified that the density distribution of the unevenness in the film with unevenness has a great influence on the glare performance, and appropriately controls it. As a result, it has been found that a high-performance anti-glare film can be obtained, and various studies have been made to complete the present invention.

That is, according to the present invention, fine irregularities are formed on the surface, the area higher than the average height of the irregularities is convex, the area lower than the average height of the irregularities is concave, and the projected area or concave of each convex Obtain the projected area, calculate the frequency of the convex or concave in a predetermined area step, calculate the apparent area frequency in the predetermined area step by area x frequency, and obtain the frequency of the apparent convex or concave area Is represented by a histogram, and an antiglare film is provided in which a peak value appears at a position of 300 μm ² or less and the half width of the peak is 60 μm ² or less.

It is more preferable that the peak value appears at a position of 150 μm ² or less. Further, it is preferable that the half width of the peak is larger than 10 μm ² .

  These antiglare films advantageously have a reflectance in the direction deviated by 20 ° from the regular reflection angle of 0.001% or less. Further, it is advantageous that the 45 ° reflection sharpness measured using an optical comb having a dark portion and a bright portion width of 1.0 mm is 50% or less. Furthermore, the total value of transmitted sharpness measured using four types of optical combs in which the width of the dark part and the bright part is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm is 200% or more. Is advantageous. These antiglare films also advantageously have a haze of 15% or less.

  Furthermore, according to the present invention, an image display device using the antiglare film is also provided, and the image display device includes any one of the above antiglare films and image display means, and the antiglare film is an image display means. It is arranged on the viewing side.

  The anti-glare film of the present invention has an appropriately controlled surface unevenness, and when applied to an image display device such as a liquid crystal display device, particularly an image display device with high definition, visibility such as glare Since the occurrence of the phenomenon that hinders the image can be effectively prevented, an image having an excellent antiglare effect and high visibility can be provided. In particular, by controlling the optical characteristics of the film together, such an effect becomes more remarkable.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings as appropriate. In the accompanying drawings, FIG. 1 is a perspective view schematically showing the surface of an antiglare film. FIG. 2 is a three-dimensional contour map in which the height of each point is plotted with respect to the surface of a part having the antiglare film. FIG. 3 is a two-dimensional contour map showing a region (convex) higher than the average height in white and a region (concave) lower than the average height in black on the surface of a part having the antiglare film. FIG. 4 is an example of a histogram in which the frequency of appearance of individual protrusions or depressions observed on the antiglare film surface is plotted against the area. FIG. 5 is an example of a histogram in which the vertical axis is expressed by area × frequency from the data of FIG. FIG. 6 is a diagram showing how to find the half width of a peak in a histogram of the apparent area of convex or concave, and is a histogram showing the horizontal axis of FIG. 5 enlarged between 0 and 200 μm ² . FIG. 7 shows an example of a method for producing an antiglare film according to the present invention in a schematic longitudinal sectional view for each step. FIG. 8 is a perspective view for explaining the regular reflection angle and the reflectance in a direction shifted by 20 ° therefrom. FIG. 9 is an enlarged view showing height information converted into gradations in the range of about 480 μm × about 640 μm of the antiglare film obtained in Example 1 described later, and is shown on the right side. The object is a gray scale representing the height. FIG. 10 is a histogram in which the frequency of appearance of individual projections or depressions observed on the surface of the antiglare film obtained in Example 1 is plotted against the area. FIG. 11 is a histogram in which the vertical axis is expressed by area × frequency from the data of FIG.

  With reference to FIG. 1, it demonstrates about the anti-glare film of this invention. The antiglare film 20 has fine irregularities 3 and 4 formed on the surface thereof, and this is not different from a conventionally known antiglare film. In FIG. 1, the surface of the average height of the film (referred to as the main plane) is indicated by reference numeral 1, the projection surface thereof is indicated by reference numeral 2, and the orthogonal coordinates in the film plane are indicated by (x, y). Further, a portion (convex) 3 higher than the average height is indicated by a solid line, and a portion (concave) 4 lower than the average height is indicated by a broken line.

In the present invention, the area higher than the average height of the irregularities is convex, the area lower than the average height of the irregularities is concave, the area of each convex or concave is obtained, and the convex or concave area is determined in increments of a predetermined area. The frequency is obtained, and the frequency of the apparent area is calculated in the above predetermined area step by area × frequency, and when the frequency of the apparent area of the obtained convex or concave is represented by a histogram, the peak value is 300 μm ² or less. The half-width of the peak appears at 60 μm ² or less.

In this histogram, the larger the area value where the peak value appears, the rougher the unevenness. A convex or concave having an area of 300 μm ² corresponds to a circle having a radius of about 10 μm, and when there are many such large convex or concave, that is, a position where the peak value in the above histogram is larger than 300 μm ^2. If it appears on the screen, the glare increases and visibility is impaired. It is more preferable that the peak value when the frequency of the apparent area of the convex or concave is represented by a histogram appears at a position of 200 μm ² or less, further 150 μm ² or less, particularly 100 μm ² or less. In addition, the half width of the peak that appears when the frequency of the apparent area of the convex or concave area is represented by a histogram corresponds to the distribution of the apparent area of the convex or concave area per unit area.

  In a conventional antiglare film, particularly an antiglare film obtained by dispersing a filler, unevenness in a part where the filler is well dispersed and unevenness in a part where the filler is poorly dispersed are observed. If only the number of irregularities is counted in such a state, in general, many irregularities with a small area in the portion where the dispersion of the filler is good are counted, while irregularities with a large area due to the aggregation of the filler are extremely large. A small number will be counted. However, when observed with an optical microscope, a stylus-type film thickness meter or the like, large irregularities due to the aggregation of the filler are conspicuously observed. Concerning optical characteristics such as glare, it is considered that such a large unevenness contributes greatly, and an evaluation method that considers the uneven area is necessary. Therefore, in the present invention, the surface structure of the antiglare film is defined by the distribution of the convex or concave apparent area in consideration of the uneven area.

  With respect to the antiglare film of the present invention, how to determine the distribution of the convex or concave apparent area on the surface and the meaning thereof will be described below. First, in an arbitrary area on the film surface, the height of each point constituting the film surface is measured, and an average value of the height in the entire measurement area is obtained. A region having a height higher than the average value is defined as convex, and a region having a height lower than the average value is defined as concave.

  2 and 3 show examples of the uneven height distribution of the antiglare film. FIG. 2 is a three-dimensional contour plot in which the height of each point on the surface of the antiglare film is plotted at a certain horizontal resolution step. On the other hand, FIG. 3 averages the heights of the points obtained as shown in FIG. 2, and a collection of points higher than the average value, that is, the convex region as referred to in the present invention is white, and from the average value. FIG. 2 is a two-dimensional contour map in which a collection of low points, that is, a concave region as referred to in the present invention is plotted in black, respectively. Then, for example, individual areas are obtained for the convex regions shown in white in FIG. Here, since the convex and concave are considered to appear almost symmetrically in the height direction, the individual areas may be obtained in this way for either the convex or concave. It is more preferable to satisfy the requirements defined in the present invention for both the convex region and the concave region. Further, the area is obtained as a projected area, not a surface area formed by the convexes or concaves. In FIG. 2 and FIG. 3, only a few irregularities are shown for the sake of clarity, but in practice, the height of the surface is obtained in a region including a large number of irregularities, and the height of the entire region is obtained. Is obtained, and the areas of a large number of protrusions or depressions are obtained.

  FIG. 4 is an example of a frequency distribution graph (histogram) in which the number of individual protrusions or depressions obtained in this way is plotted in predetermined area increments. Further, in order to calculate the apparent area, the product of the area interval and the frequency is obtained from the frequency value for the predetermined area increment obtained to obtain the apparent area frequency. FIG. 5 is an example of a frequency distribution graph (histogram) in which the apparent area frequency thus obtained from the graph of FIG. 4 is plotted in the aforementioned predetermined area increments.

  As shown in FIG. 4, in the histogram in which the number (frequency) of protrusions or depressions is plotted against the area, there are many protrusions or depressions with a small area and few protrusions or depressions with a large area. The contribution by the convex or concave having a large area is large. Therefore, in the present invention, the frequency of the apparent area is obtained by multiplying the frequency by the area, and the distribution of the apparent area is obtained from a histogram obtained by plotting the frequency. In this specification, the peak half-width (also referred to as full width at half maximum) in the apparent area histogram thus obtained is referred to as an apparent area distribution. The method for obtaining the apparent area distribution will be described in more detail below.

  The height of the film surface on which the irregularities are formed is the surface roughness measured using a non-contact 3D surface shape / roughness measuring machine, an atomic force microscope (AFM), a laser confocal microscope, etc. The three-dimensional shape can be obtained. The horizontal resolution required for the measuring instrument is at least 5 μm or less, preferably 2 μm or less, and the vertical resolution is at least 0.1 μm or less, preferably 0.01 μm or less. As a non-contact three-dimensional surface shape / roughness measuring instrument suitable for this measurement, “New View 5000” series, which is a product of Zygo Corporation of the United States and available from Zygo Corporation in Japan, can be cited. A wider measurement area is preferable, but at least 100 μm × 100 μm or more, preferably 400 μm × 400 μm or more.

  Specifically, by using the above-described measuring instrument or the like, height data corresponding to each grid-like x and y coordinate determined by the horizontal resolution of the measuring instrument as shown in FIG. 2 is obtained. An average value of all the height data is taken, and a region having a height higher than the average value is regarded as convex, and a region having a height lower than the average value is regarded as concave. The unevenness obtained in this way is converted into a binarized image, and the convex or concave area is calculated using image processing software. The image processing software is not particularly limited as long as the number of convex or concave pixels can be counted. In the examples shown in FIGS. 4 and 5 and the embodiments described later, NIH image is used as the image processing software. Then, the number of pixels corresponding to each of the convexity or concaveness of the binarized image was counted to obtain the area. NIH image is image processing software developed at the National Institute of Health (NIH) in the United States, and is named NIH image after the name of the development organization.

Next, the area is divided into equal parts so that the area between the maximum area and the minimum area obtained by the image processing can be equally divided by 10 to 100, and the convexity corresponding to the area between the divided adjacent areas is obtained. Or count the number of depressions and find the frequency. If the area division is too fine, the frequency becomes too discrete and it is difficult to obtain the distribution. Conversely, if the area division is too large, the frequency can be seen only roughly, which is not preferable. In the examples shown in FIGS. 4 and 5 and the examples described later, the area is divided at intervals of 10 μm ² . That is, in FIG. 4 and FIG. 5, the horizontal axis area is displayed at intervals of 10 μm ² , “0” in the first segment means 0 μm ² or less, and the next segment is from 0 μm ^2. The area is up to 10 μm ² , and the subsequent division of, for example, “50” means an area from 40 μm ² to 50 μm ² . The same applies to the following FIGS. 6, 10 and 11 showing the histogram.

Further, in order to obtain the apparent area distribution, the product of the average value of each adjacent area and the number (frequency) of convexes or concaves belonging to the section is taken as the apparent area frequency. For example, when the area is divided at intervals of 10 μm ² , if there are five convex or concave numbers between 20 μm ² and 30 μm ² (intermediate value 25 μm ² ), the frequency of the apparent area is 25 μm ² × 5 = 125 μm ² . The frequency of the apparent area obtained is plotted against the area value, and a histogram of the apparent area is created. The distribution of the apparent area of the unevenness was defined as the half width of the peak of this histogram. The peak value in the histogram of the "area × frequency" to the area, the maximum value of the "area × frequency" in the histogram obtained as described above, i.e., in the example of FIG. 5, the 20 [mu] m ² and 30 [mu] m ² The value that appears in the area break between.

Here, a method of obtaining the half width of the peak in the histogram will be described with reference to FIG. FIG. 6 is an enlarged view of the histogram of FIG. 5 with the horizontal axis in the range of 0 to 200 μm ² . And the point which shows the value with the largest vertical axis | shaft (area x frequency) among the whole measurement range is made into the point P which shows a peak value. A perpendicular line A is drawn from this point P with respect to the horizontal axis, and the point where it intersects with the straight line of the horizontal axis area × frequency = 0 is defined as the base point B, and the horizontal line passes through the point C that bisects the peak line segment PB A straight line (half-value line) parallel to the axis is drawn, and an area interval between the minimum value and the maximum value at which it intersects the histogram is defined as a half-value width WH. In addition, as shown in FIG. 6, when the histogram descending from the point P indicating the peak value rises again before reaching the half value of the peak value, or rises again after the histogram becomes equal to or less than the half value of the peak value. When the half value is exceeded, the histogram never exceeds the half value of the peak value again. Finally, points U and V exceeding the half value are determined, and the width between the UVs is determined as the half value width WH. In determining the half-value width WH, the minimum value at which the half-value line intersects the histogram is the minimum value of the area delimiter represented by the bar column, and the maximum value at which the half-value line intersects the histogram is the maximum value of the area delimiter represented by the bar column. To do. That is, in the example shown in FIG. 6, because the half line with smaller in area intersects the rod columns and last representative of the area between the 10 [mu] m ² and 20 [mu] m ^2, the value of the point U is set to 10 [mu] m ^2, also Since the half-value line intersects with the rod column representing the area between 140 μm ² and 150 μm ^{2 at} the end of the larger area, the value of the point V is 150 μm ^2, and therefore the half-value width WH in this example is 140 μm ² (= 150-10).

  In the histogram for the area of “area × frequency” obtained as described above, if the half width of the peak is zero, the convex or concave area is concentrated at one point. On the other hand, an increase in the half-value width means that the distribution of the apparent area of each of the irregularities is wide (large). The smaller the half-value width, the narrower (smaller) the distribution of the apparent area of each of the irregularities.

When the distribution of the apparent area is wide, it corresponds to the fact that the convex or concave having a large appearance and the convex or concave having a small apparent are mixed, and although the cause is not clear, it has been found that the glare increases. In addition, when the apparent area distribution is narrow, it has been clarified that the glare is reduced when combined with a high-definition panel, corresponding to the relatively uniform convex or concave areas. When the apparent area distribution, that is, the half width of the peak in the histogram representing the frequency of the above-described apparent area exceeds 100 μm ² , the glare increases and the visibility is significantly reduced. On the other hand, if the apparent area distribution (peak half width) is 60 μm ² or less, glare is hardly observed and good visibility can be obtained. Therefore, in order to improve the visibility in a high-definition display device in particular, it is important that the apparent area distribution (peak half-value width) is 100 μm ² or less, and preferably the half-value width is 60 μm ² or less. To be. The half width of the peak in the histogram showing the frequency of the apparent area is more preferably 50 μm ² or less. However, when the irregularities are regularly arranged and the half width becomes zero, the interference fringes become conspicuous, and this tendency appears when the half width becomes 10 μm ² or less. Therefore, it is preferable that the apparent area of the convex or concave has a certain distribution, and it is preferable that the above half-value width is larger than 10 μm ² .

  The film having the surface shape specified in the present invention can be produced by an arbitrary method. For example, a thermoplastic transparent resin film is pressed into an embossed mold having an appropriate surface shape in a heated state, and is shaped. The method can be prepared by, for example, a method in which a transparent base material coated with an ultraviolet curable resin is adhered to the embossed mold on the ultraviolet curable resin coating surface and cured by irradiating ultraviolet rays in that state. it can.

  As a method for producing the embossing mold, for example, a method in which formation of unevenness by photolithography and electroforming (electroplating) of metal thereon is combined is preferable. Specifically, a photoresist film is formed on a substrate, subjected to gradation exposure, and then developed to form irregularities on the photoresist film, and the photoresist film on which the irregularities are formed After the metal is electroformed thereon, the metal plate is peeled off from the photoresist film, thereby producing a metal plate to which the concavo-convex shape is transferred, that is, an embossing mold. Using this embossing mold, a thermoplastic transparent resin film is pressed against the embossing mold in a heated state, or a transparent substrate coated with an ultraviolet curable resin is adhered to the embossing mold on its ultraviolet curable resin coating surface. In such a state, an antiglare film having a predetermined surface shape can be obtained by, for example, a method of irradiating ultraviolet rays to cure the ultraviolet curable resin.

  Thus, the example of the method of producing an embossing casting_mold | template by the combination of photolithography and electroforming, and producing an anti-glare film using it is demonstrated based on FIG. First, as shown in FIG. 7A, a photoresist film 12 is formed on the surface of a substrate 11 for forming a photoresist film. The base material 11 used here may be any material as long as the surface is flat and the photoresist film adheres appropriately. For example, an inorganic transparent base material such as glass, quartz, and alumina, copper, and stainless steel. And a metal base material such as The photoresist applied on the substrate 11 may be any photo-sensitive photoresist having an appropriate resolution, and the exposed portion becomes soluble in the developer and removed after development. Either a resist or a negative photoresist in which an exposed portion is cured and becomes insoluble in a developer, and an unexposed portion is removed by development can be used. However, in the subsequent exposure step, a positive photoresist is preferable in order to cause light diffraction at the edge portion by proximity exposure and to form a rounded recess by subsequent development. Examples of positive photoresists include novolak resins, acrylic resins, copolymers of styrene and acrylic acid, alkali-soluble resins such as polyvinylphenol and poly (α-methylvinylphenol), and quinonediazide group-containing compounds. Examples thereof include a composition obtained by dissolving such a photosensitive compound in an organic solvent. The example shown below with reference to FIG. 7 is a case where a positive photoresist is used.

  The thickness of the photoresist film formed on the substrate 11 may be adjusted as appropriate depending on the depth and shape of the unevenness to be formed on the surface of the antiglare film, and is equivalent to the desired unevenness depth, or It is preferable to form the film slightly thicker. As a specific range of the film thickness, it is preferable to be not less than the depth of the target unevenness and not more than the depth of the target unevenness + 5 μm or less.

  In order to form the photoresist film 12 on the substrate 11, a known appropriate coating method such as a spin coating method, a dip coating method, or a roll coating method can be employed. After film formation, pre-baking is usually performed in order to remove the solvent contained in the photoresist. The pre-baking is performed, for example, using a hot plate or an oven at a temperature of about 60 to 120 ° C. for about 0.5 to 10 minutes. The pre-baking temperature and time can be appropriately adjusted depending on the type of photoresist and the sensitivity required for the photoresist.

  The photoresist film 12 thus formed on the substrate 11 is then subjected to gradation exposure as shown in FIG. 7B. FIG. 7B shows an example in which gradation exposure is performed through a two-gradation photomask 14. A two-tone photomask has a transparent part that transmits light from the exposure light source and a light shielding part that blocks light from the exposure light source on a substrate made of glass or quartz that is transparent to the exposure light source. It is a thing. Specifically, for example, a metal mask in which a metal such as chromium is formed as a light shielding part on a substrate transparent to the exposure light source, or an emulsion mask in which a light shielding part is formed by exposing an emulsion or the like. It is done.

  Such a two-tone photomask 14 is arranged at a slight distance from the surface of the photoresist film 12 as shown in FIG. 7B, and proximity exposure is performed. Proximity exposure means that the photomask 14 is brought close to the photoresist film 12 as described above, but is not closely contacted but is arranged at a slight interval and exposed. Proximity exposure using such a two-tone photomask 14 causes light diffraction at the edge portion of the mask pattern of the photomask 14, and the image of the photomask 14 is blurred and passes through the transmission portion. The light beam 15 spreads over the back surface of the light shielding portion, and a continuous light amount distribution is generated. Then, since the photoresist film 12 is exposed in accordance with the distribution of the light quantity subjected to the proximity exposure, the subsequent development changes the photoresist remaining film in accordance with the irradiation light quantity, and the surface of the developed photoresist film 12 is changed. Asperities are formed according to the mask pattern, the exposure amount, the distance between the photomask and the photoresist film (referred to as “exposure gap” or “proximity gap”), and the like. At this time, the opening diameter of the photomask may be only one type, but it is also effective to form a photomask by combining a plurality of types, for example, two types or three types of opening diameters.

  FIG. 7B shows an example in which gradation exposure is performed by proximity exposure using a two-gradation photomask 14, but gradation exposure is also performed through a multi-gradation photomask. The same effect can be obtained by a method in which gradation exposure is performed via a spatial light modulation element capable of changing the light intensity of the exposure light source depending on the method and location.

  Unlike the above-described two-tone photomask, the multi-tone photomask is a photomask whose transmittance changes in multiple steps or continuously depending on the location. As such a multi-tone photomask, for example, using a high-resolution photomask drawing apparatus such as an electron beam drawing apparatus, a light shielding part and a transmission part having a size sufficiently smaller than the wavelength of the exposure light are provided, and light shielding is performed. High-energy mask blanks in which gradation is expressed by the area ratio between the area and the transmission area, or a mask blank in which a material whose transmittance is changed by exposure to a high-energy beam such as an electron beam or a laser beam is dispersed in a transparent medium The light beam is irradiated so that its intensity varies depending on the location, and the transmittance is changed continuously. It has photosensitivity like an emulsion, and the optical density changes according to the amount of light irradiated. It is possible to use a material in which a substance is formed on a base material, the quantity of light is changed to expose the substance, and the optical density is changed depending on the place.

  On the other hand, a spatial light modulator capable of changing the light intensity of the exposure light source depending on the location can spatially change the intensity of light transmitted through the element or reflected by the element. For example, a light modulation element in which a large number of pixels including a liquid crystal element, a digital micromirror device (DMD), and the like are arranged can be given. When a liquid crystal element is used as a spatial light modulation element, the transmittance can be set for each individual pixel of the liquid crystal elements that make up a plurality of pixels, so that there is a spatially uniform intensity distribution from the exposure light source. By passing the transmitted light through the liquid crystal element, it is possible to obtain an exposure light intensity distribution according to the transmittance of the pixel of the liquid crystal element, and a spatial intensity distribution of the exposure light irradiated to the photoresist film is generated. It will be. In addition, when DMD is used as a spatial light modulation element, the reflection of light in the direction of the photoresist film and the reflection in a direction other than the photoresist film are appropriately changed depending on the inclination angle of the micromirror. However, by changing the reflection time in the direction of the photoresist film for each pixel, the substantial reflectance per unit time can be changed for each pixel. That is, by reflecting light having a spatially uniform intensity distribution from the exposure light source with the DMD, it is possible to obtain the intensity distribution of the exposure light according to the time when the micromirror is inclined, and the photoresist film Thus, a spatial intensity distribution of the exposure light applied to the light beam occurs.

  The light source used for exposure is not particularly limited as long as it can sensitize the photoresist film 12, and an appropriate light source is used according to the type of the photoresist. For example, using a high-pressure mercury lamp or an ultrahigh-pressure mercury lamp as a light source, using near ultraviolet rays such as g-line, h-line, and i-line, or using laser light having a transmission wavelength close to the emission line of these mercury can do.

  The photoresist film 12 thus subjected to the gradation exposure is then subjected to a development process, whereby a photoresist film 13 having irregularities is obtained, as shown in FIG. 7C. In the development process, for example, the exposed photoresist film 12 formed on the substrate 11 is brought into contact with a developer corresponding to the type thereof, and in the case of a positive type photoresist, the exposed portion is removed to remove the photoresist. Unevenness is formed on the film 12. The developer can be appropriately selected from conventionally known ones according to the type of the photoresist. After the development, it is usually rinsed with water and further post-baked. By post-baking, the strength of the remaining photoresist film can be improved and the adhesion to the substrate 11 can be improved. The post-baking is performed, for example, using an oven or a hot plate at a temperature of about 100 to 200 ° C. for a time of about 0.5 to 30 minutes.

  Next, as shown in FIG. 7D, the metal film 17 is electroformed on the photoresist film 13 having the unevenness formed thereon, and the unevenness on the surface of the photoresist film 13 is transferred to the electroformed metal 17. To do. The metal used for electroforming may be conventionally used in the field of electroplating, and examples thereof include nickel, nickel-phosphorus alloy, iron-nickel alloy, chromium, and chromium alloy. The thickness of the metal 17 formed on the photoresist film 13 by electroforming is not particularly limited, but is preferably about 0.05 to 3 mm from the viewpoint of durability. When electroforming directly on the photoresist film 13, it is necessary to make the surface of the photoresist film 13 conductive before electroforming. For example, a metal film having a thickness of 1 μm or less is deposited or evaporated. It can be performed by a method of forming by sputtering or the like or a method of electroless plating. When it is not desired to perform electroforming directly on the photoresist film 13, for example, the concave shape on the photoresist film 13 is not formed by transferring the concave shape on the photoresist film 13 to the metal 17. When it is desired to transfer the same material to the metal 17 to form a concave shape, for example, after transferring the concave / convex shape formed on the photoresist film 13 to the resin, the concave / convex surface of the resin is transferred by the method described above. A method of conducting a conductive treatment and electroforming the same can be employed.

  The metal plate 17 to which the unevenness of the photoresist film 13 with the unevenness was transferred was then peeled off from the photoresist film 13 or transferred to the resin and electroformed there. In this case, the resin plate is peeled off from the resin to form a metal plate having an uneven surface as shown in FIG.

  Using the embossed mold 18 thus obtained, the unevenness formed on the surface thereof is transferred onto the film to obtain an antiglare film. In the example shown in FIGS. 7F and 7G, the ultraviolet curable resin 22 is applied on the transparent base film 21, and the ultraviolet curable resin 22 is brought into close contact with the embossing mold 22 so that the state is shown. The ultraviolet curable resin 22 is cured by irradiating ultraviolet rays from the transparent substrate film 21 side to obtain an antiglare film 20 in which a layer of the ultraviolet curable resin 22 having irregularities is formed on the transparent substrate film 22. It has become. Not limited to this example, as described above, an antiglare film having irregularities formed on the surface is obtained by a method in which a thermoplastic transparent resin film is pressed against the embossing mold 18 in a heated state and molded. be able to.

  In the above description, according to (A) to (E) of FIG. 7, the photoresist film 12 is subjected to gradation exposure and developed to form an unevenness, and finally, on the film. The antiglare film 20 having the uneven shape transferred continuously is produced. Therefore, it is necessary to design a mask pattern in order to produce the original photomask 14, but this mask pattern is designed so as to obtain the shape defined in the present invention. Designing such a mask pattern over the entire surface of the photomask 14 is a very time-consuming operation, and since the data capacity of the mask pattern increases, the burden on the mask drawing machine also increases. Is possible, but not necessarily realistic. Therefore, it is advantageous to design a mask pattern that constitutes a unit cell having a predetermined area, and to arrange a plurality of such unit cells in the front, rear, left, and right to form a photomask that covers the entire surface of the photoresist film 12. By adopting such a method, it is possible to reduce time and effort for designing the mask pattern of the photomask 14 as a whole, which is industrially advantageous.

  Further, the surface of the metal plate on which the unevenness is formed as described above, that is, the embossing mold 18 is wound around a roll, or the embossing mold 18 is wound around the roll surface as necessary. A method is also suitable in which an embossed roll having irregularities is prepared and the irregular shape is continuously transferred to the film surface using the embossed roll. By adopting such a method, the concavo-convex shape can be continuously and efficiently transferred to a film having a large area, and high productivity can be obtained.

  When an embossing mold is produced by a method combining the formation of unevenness by photolithography and electroforming of metal thereon, as described above, and using this to transfer the unevenness to the film surface, the photomask pattern By appropriately selecting the conditions such as the exposure amount and the exposure gap, an antiglare film having the surface shape defined in the present invention can be produced.

  As described above, this antiglare film is a method of irradiating ultraviolet rays in a state where an embossing mold obtained by the above method is pressed on a transparent substrate film coated with an ultraviolet curable resin, It can be produced by any method such as a method of pressing the transparent film against an embossing mold in a heated state. The transparent substrate film only needs to be substantially optically transparent, and examples thereof include resin films such as a triacetyl cellulose film and a polyethylene terephthalate film.

  A commercially available product can be used as the ultraviolet curable resin. For example, polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are used alone or in admixture of two or more thereof, and “Irgacure 907”, “Irgacure 184” (above, Ciba A product obtained by mixing a photopolymerization initiator such as “Specialty Chemicals” or “Lucirin TPO” (BASF) can be used as an ultraviolet curable resin.

  As the thermoplastic transparent film, any material that is substantially transparent can be used. For example, a solvent cast film of thermoplastic resin such as polymethyl methacrylate, polycarbonate, polyethylene terephthalate, or extrusion A film or the like can be used.

  The glare of the antiglare film can be evaluated by placing the antiglare film on a high-definition liquid crystal panel, illuminating the liquid crystal panel and the antiglare film with light from the backlight, and visually inspecting the panel surface. . As the liquid crystal panel used for evaluating the glare, the higher the resolution, the better the glare can be seen. The definition of the panel is preferably 150 ppi (pixel per inch) or more, more preferably 170 ppi or more.

  The antiglare film of the present invention preferably has a reflectance in a direction deviated by 20 ° from the regular reflection angle of 0.001% or less. Here, as shown in FIG. 8, when the light ray 6 is incident at an angle ψ with respect to the main normal line 5 of the film 20, the regular reflection angle is within a plane 7 including the normal line 5 and the incident light beam direction 6. The direction of the light 8 reflected at an angle ψ in the direction opposite to the incident light direction 6 is an angle formed with respect to the main normal 5. ψ is an incident angle, which is also a regular reflection angle, but strictly speaking, the sign is reversed. The direction deviated by 20 ° from the regular reflection angle means a direction 9 deviated by 20 ° from the regular reflection direction 8 as shown in FIG. The direction 9 deviated by 20 ° from the regular reflection angle appears in a conical shape with the regular reflection direction 8 as the center, but the reflectance in the direction deviated by 20 ° from the regular reflection angle here is incident on the normal line 5 described above. It means the reflectance in a direction shifted by 20 ° to the film side in the plane 7 including the light beam direction 6.

  In addition, this antiglare film preferably has a 45 ° reflection sharpness of 50% or less measured using an optical comb having a dark portion and a bright portion width of 1.0 mm. The 45 ° reflection sharpness can be determined according to the image sharpness measurement method by the reflection method specified in JIS K 7105. The incident direction and reflection direction of light on the test piece at the time of measurement shall be 45 ° in accordance with the provisions of this JIS. In this JIS, four types of optical combs are defined, in which the ratio of the width of the dark part to the bright part is 1: 1 and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The 45 ° reflection definition defined in the present specification and claims is a value obtained when an optical comb having a dark portion and a bright portion width of 1.0 mm is used.

  Furthermore, this anti-glare film has a total transmission sharpness value measured using four types of optical combs in which the width of the dark part and the bright part is 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm. It is preferably 200% or more. The transmission definition can also be determined according to the image definition measurement method by the transmission method similarly defined in JIS K 7105. The incident direction of light on the specimen shall be the vertical direction in accordance with this JIS standard. In this case, the image definition by the transmission method is measured for each of the four types of optical combs, and the total value thereof is set as the total value of the transmission definition.

  Furthermore, the antiglare film of the present invention preferably has a haze of 15% or less. The haze value can be obtained by the method specified in JIS K 7105. The haze value is a value represented by (diffuse transmittance / total light transmittance) × 100 (%). In the antiglare film of the present invention, the haze value measured by this method is generally 20% or less, but the haze value is preferably 15% or less, and more preferably 10% or less. Is more preferable. When the haze value is too high, when this antiglare film is applied to a display device, particularly a liquid crystal display device, the viewing angle characteristics of the liquid crystal display device are inclined from the normal, particularly in a direction inclined by 60 ° or more. Since the emitted low-contrast light is scattered and observed in the front direction, the contrast is lowered when observed from the front.

  By appropriately selecting the conditions in the mold manufacturing method and the unevenness forming method described above, an antiglare film satisfying the above optical characteristics can be produced. For example, when an embossing mold is produced by a method that combines concavo-convex formation by photolithography and metal electroforming thereon, and the concavo-convex pattern is transferred to the film surface using it, the photomask opening diameter and exposure amount By appropriately selecting conditions such as the exposure gap, an embossing mold suitable for giving a surface shape satisfying the above optical characteristics may be produced, and an antiglare film may be produced using this.

  The anti-glare film of the present invention configured as described above has an excellent anti-glare effect and has improved glare when combined with a high-definition display panel, so that it is visible when mounted on an image display device. Excellent in properties. When the image display device is a liquid crystal display, the antiglare film can be a polarizing film. That is, in general, a polarizing film is often in a form in which a protective film is laminated on at least one surface of a polarizer made of a polyvinyl alcohol-based resin film on which iodine or a dichroic dye is adsorbed and oriented. If an antiglare film with the above irregularities is bonded to one surface, an antiglare polarizing film is obtained. In addition, the above-mentioned optical film provided with antiglare unevenness is used as a protective film and antiglare layer, and is bonded to one side of a polarizer so that the uneven surface is on the outside. A dazzling polarizing film can be obtained. Furthermore, in the polarizing film in which the protective film is laminated, the antiglare polarizing film can be obtained by providing the antiglare unevenness as described above on the surface of the single-sided protective film.

  In the image display device of the present invention, an antiglare film having a specific surface shape as described above is arranged in the image display means. Here, the image display means is typically a liquid crystal panel that includes a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates and displays an image by changing the alignment state of the liquid crystal by applying a voltage. A panel, an electroluminescence (EL) or organic light emitting diode (O-LED) display body, a cathode ray tube (CRT) display body, etc. can also be mentioned. And an image display apparatus is comprised by arrange | positioning said anti-glare film on the visual recognition side rather than an image display means. Under the present circumstances, it arrange | positions so that the uneven surface of an anti-glare film may become an outer side (viewing side). The antiglare film may be directly bonded to the surface of the image display means. When the liquid crystal panel is used as the image display means, for example, as described above, the antiglare film is bonded to the surface of the liquid crystal panel via the polarizing film. You can also. Thus, the image display device provided with the antiglare film of the present invention can scatter incident light due to the unevenness of the surface of the antiglare film and blur the reflected image, giving excellent visibility. .

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by these examples. In the examples,% representing the content or amount used is based on weight unless otherwise specified. Moreover, the evaluation and measurement methods of the antiglare film in the following examples are as follows.

(Measurement of surface shape and calculation of apparent area of convex or concave)
Using a non-contact three-dimensional surface shape / roughness measuring device “New View 5010” (manufactured by Zygo Corporation), the surface shape was measured for an area of about 480 μm × 640 μm of the antiglare film. This measuring machine has a horizontal resolution of 1.18 μm and a vertical resolution of 0.1 nm. Taking the average value of all the obtained height data, converting the area higher than the average height (convex) and the area lower than the average height (concave) into a binarized image by the image processing software "NIH image" Furthermore, the area of each convex or concave was determined. The resulting individual area data is divided by 10 [mu] m ² increments, to determine the frequency (number) of each 10 [mu] m per ^2. Then, by multiplying the frequency of above average area of each 10 [mu] m ² increments was determined the frequency of the apparent area of each 10 [mu] m per ^2. The frequency of the apparent area thus obtained was plotted against the area value, and a graph (histogram) of the frequency distribution of the apparent area was created. From this histogram, the half width of the peak, that is, the distribution of the apparent area was obtained.

(Measurement of reflectance of antiglare film)
The light from the collimated halogen lamp light source is condensed and irradiated so as to form a solid angle of 3.4 ° from the direction inclined by 30 ° with respect to the main line normal to the uneven surface of the antiglare film. The change in the angle of reflectivity in the plane including the main normal and the irradiation direction was measured. For the measurement of reflectance, both “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation were used.

(Measure haze)
Measured according to JIS K 7105. In order to prevent warpage, the sample was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface becomes the surface.

(Measurement of reflection definition and transmission definition)
Measured according to JIS K 7105. When measuring the transmission clarity, in order to prevent the curvature of a sample, it bonded to the glass substrate using the optically transparent adhesive, and used for the measurement. When measuring the reflection definition, the same glass-bonded sample used for the measurement of the transmission definition was used, but in order to prevent reflection from the glass surface, the glass plate with an antiglare film attached A black polymethyl methacrylate plate having a thickness of 2 mm was adhered to the surface with water, and light was incident from the sample (antiglare film) side in this state, and measurement was performed.

Example 1
In a 10 mm × 10 mm region, there are a total of 512,820 circular openings of 3 types with diameters of 8 μm, 9 μm and 10 μm in total, and the average value of the shortest distance between the center coordinates of each opening is 12.0 μm. A unit cell arranged as described above was designed. A two-tone photomask was prepared in which this unit cell was arranged at a period of 10 mm over the entire area of 100 mm × 100 mm on a 6-inch square (about 152 mm square) quartz substrate.

On the other hand, “P70BK” manufactured by Tokyo Ohka Kogyo Co., Ltd., which is a positive type photoresist mixed with a black pigment on a 100 mm × 100 mm glass substrate, is spinned so that the thickness after pre-baking is about 1.1 μm. Coated. The glass substrate with the photoresist film thus obtained was placed on a hot plate set at 85 ° C. for 120 seconds and prebaked. On this photoresist film, the photomask produced above is held so that the exposure gap becomes 120 μm, and the g-line, h-line, and i-line from the ultra-high pressure mercury lamp as the exposure light source are passed through the photomask. Proximity exposure was performed by irradiating multiline light so as to be 240 mJ / cm ^{2 in} terms of g-line. The exposed glass substrate with a photoresist film was developed with a 0.5% aqueous potassium hydroxide solution at 23 ° C., and then rinsed with pure water. Then, the resin layer in which many hollows were formed in the surface was obtained by heating (post-baking) for 20 minutes in the oven heated at 180 degreeC.

  A nickel film was formed by vapor deposition on the resin layer with dents thus obtained, and a conductive treatment was performed on the surface of the resin layer. Next, a nickel film was formed on the conductive surface so as to have a thickness of about 0.3 mm by electroforming. With the nickel film attached on the resin layer with the depression, the back surface of the nickel film was ground and further polished to a thickness of 0.15 mm. The nickel film after polishing was peeled off from the resin layer with the depressions to produce a nickel plate having a large number of protrusions on the surface.

Separately, an ultraviolet curable resin “GRANDIC PC806T2” manufactured by Dainippon Ink & Chemicals, Inc. was dissolved in ethyl acetate to a concentration of 50% to prepare a coating solution. This coating solution was applied onto a triacetyl cellulose film so that the film thickness after drying was about 5 μm, and dried in an oven at 60 ° C. for 3 minutes. Furthermore, after pressing with a rubber roll so that the coated surface of the ultraviolet curable resin is in contact with the convex surface of the nickel plate with protrusions produced earlier, the light from the electrodeless ultraviolet lamp is converted into the amount of h-line converted light from the triacetyl cellulose film side. The ultraviolet curable resin was cured by irradiation at 100 mJ / cm ² . The triacetyl cellulose film was peeled from the nickel plate together with the cured resin to obtain a transparent antiglare film comprising a laminate of a cured resin having irregularities on the surface and the triacetyl cellulose film.

The surface shape of the antiglare film was measured in a region of about 480 μm × 640 μm using the above-described non-contact three-dimensional surface shape / roughness measuring device “New View 5010” manufactured by Zygo Corporation. When the height information of the antiglare film was converted into gradation and displayed, the data shown in FIG. 9 was obtained. Furthermore, the area of each concave was obtained from the height information by the above-described method, and the concave area histogram shown in FIG. 10 was obtained. The maximum value of the concave area observed at this time is about 584μm ^2, the minimum value is about 5 [mu] m ^2, the interval of the area at the histogram created (increments) was 10 [mu] m ^2. Next, frequency × area was calculated by the above-described method, and an apparent area histogram shown in FIG. 11 was obtained. In this histogram, a peak (maximum value) was observed at a break between 40 μm ² and 50 μm ² . When determining the half width of the peak from the histogram of the apparent area of shown in FIG. 11, 30 [mu] m ^2, and the smaller than 100 [mu] m ^2. Therefore, this film has a small distribution of apparent areas of irregularities.

  When the obtained antiglare film was placed on a 200 ppi high-definition liquid crystal panel and illuminated with a backlight from behind, the glare was visually evaluated, and no glare was observed. Further, this antiglare film had a reflectance in the regular reflection direction of 0.92%, and a reflectance in a direction shifted from the regular reflection angle by 20 ° toward the film side was 0.0025%.

  The anti-glare film's triacetyl cellulose surface is bonded to glass to measure haze, and the reflection sharpness at 45 ° incidence is measured using an optical comb whose dark and bright portions are 1.0 mm wide. did. As a result, it was confirmed that the haze was 8.0% and the reflection sharpness was 44.5%. In addition, the anti-glare film in the state of being pasted on glass was measured for transmission definition using optical combs having a width of 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm in the dark part and the bright part. Each of these values was as follows, and the total value of these four kinds of transmitted sharpnesses was 297.4%, and it was confirmed that they had high sharpness.

0.125mm optical comb: Transmission sharpness 70.5%
0.5mm optical comb: Transmission sharpness 75.0%
1.0 mm optical comb: Transmission sharpness 75.6%
2.0mm optical comb: Transmission sharpness 76.3%
Total 297.4%

  The above evaluation and measurement data in Example 1 are summarized in Table 1.

Example 2
A total of 588,069 circular openings of 3 types with diameters of 8 μm, 9 μm, and 10 μm in a 10 mm × 10 mm region, and the average value of the shortest distance between the center coordinates of each opening is 11.6 μm. An antiglare film was prepared in the same manner as in Example 1 except that a two-tone photomask in which unit cells arranged in this manner were arranged at a period of 10 mm over the entire area of 100 mm × 100 mm was used. When the distribution of the apparent area of the concave formed on the surface of the obtained film was evaluated, a peak (maximum value) of “area × frequency” was observed at a break between 60 μm ² and 70 μm ² . The half width was 30 μm ² . Moreover, when the glare was visually evaluated by the same method as in Example 1, no glare was observed. Further, other optical characteristics of the antiglare film were as shown in Table 1.

Comparative Example 1
For the anti-glare film “AG6” sold by Sumitomo Chemical Co., Ltd., the distribution of the apparent area of the protrusions formed on the surface was evaluated in the same manner as in Example 1. The peak was 20 μm ² . It was observed at intervals between 30 μm ² , and the half width of the peak was 140 μm ² . Furthermore, when the glare was visually evaluated by the same method as in Example 1, it was difficult to see the glare. The other optical characteristics of the antiglare film were as shown in Table 1.

Comparative Example 2
For the antiglare film “GH5” sold by Sumitomo Chemical Co., Ltd., the distribution of the apparent area of the protrusions formed on the surface was evaluated in the same manner as in Example 1. The peak was 10 μm ² . Observed at intervals between 20 μm ² , the half width of the peak was larger than 300 μm ² . Furthermore, when the glare was evaluated by visual observation, the glare was observed and it was difficult to see. The other optical characteristics of the antiglare film were as shown in Table 1.

[Table 1]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Optical distribution of apparent area Visual characteristics Visual evaluation
Peak half-value width 20 ° shifted haze reflection transmission glare
Directional reflectance Sharpness Sharpness
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Example 1 40-50 μm ² 30 μm ² 0.00025% 8.0% 44.5% 297.4% ○
〃 2 60-70μm ² 30μm ² 0.00019% 5.9% 21.8% 311.0% ○
───────────────────────────────────────
Comparative Example 1 20-30 μm ² 140 μm ² 0.00670% 32.4% 4.7% 31.7% ×
〃 2 10-20μm ² > 300μm ² 0.00046% 49.4% 4.4% 57.4% ×
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Remarks) Transmission clarity is the total of four types.

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

It is a perspective view which shows the outline of the surface shape of an anti-glare film. It is the three-dimensional contour map which plotted the height of each point about the surface of the part with an anti-glare film. It is the two-dimensional contour map which showed the area | region (convex) higher than average height in white and the area | region (concave) lower than average height in black about the surface of the part with an anti-glare film, respectively. It is an example of a histogram in which the frequency of individual protrusions or depressions observed on the antiglare film surface is plotted against the area, the horizontal axis is the area (unit is μm ² ), and the vertical axis is the convexity or Indicates the frequency (unit is number) of appearance of recesses. FIG. 5 is an example of a histogram in which the vertical axis is expressed by area × frequency (unit: μm ² ) from the data in FIG. A diagram showing how to determine the half-width of the peak in the histogram of the area of the projection or concave apparent, the horizontal axis of FIG. 5 is a histogram showing the enlarged between 0~200μm ^2. An example of the manufacturing method of the anti-glare film which concerns on this invention is shown with a longitudinal cross-section schematic diagram for every process. It is a perspective view for demonstrating the regular reflection angle and the reflectance in the direction shifted 20 degrees from there. About the range of about 480 μm length × about 640 μm width of the antiglare film obtained in Example 1, the height information is converted into gradation and displayed, and the one shown on the right side shows the height. Represents grayscale. It is the histogram which plotted the frequency which the individual convex or concave part observed on the surface appears about the anti-glare film obtained in Example 1 to the area. 10 is a histogram in which the vertical axis represents area × frequency (unit: μm ² ) from the data in FIG.

Explanation of symbols

1 …… Main plane of anti-glare film,
2 …… Projection surface of film
3 ... Convex on the film surface (area higher than average height)
4 ... concave on the film surface (area lower than average height),
5 …… The main normal of the film,
6 …… Incoming ray direction,
7 …… Surface including the main normal of the film and the incident light direction,
8 …… Specular reflection direction,
9 …… A direction deviated by 20 ° from the regular reflection angle,
ψ …… incident angle (= regular reflection angle),
11 ... Substrate for forming a photoresist film,
12 …… Photoresist film,
13: Photoresist film with irregularities formed,
14 …… Photomask,
15 …… Exposure flux after passing through photomask,
17 …… Electroformed metal,
18 …… Embossed mold,
20 ... Anti-glare film,
21 …… Transparent substrate film,
22: UV curable resin or cured product thereof.

Claims (8)

An anti-glare film with fine irregularities formed on the surface, where convex areas are higher than the average height of the irregularities, concave areas are lower than the average height of the irregularities, and projections of individual convex areas or concave projections Find the area, calculate the frequency of the convex or concave in a predetermined area step, further calculate the frequency of the apparent area in the predetermined area step by area × frequency, and calculate the frequency of the apparent convex or concave area obtained An anti-glare film characterized in that, when represented by a histogram, a peak value appears at a position of 300 μm ² or less, and a half width of the peak is 60 μm ² or less. The antiglare film according to claim 1, wherein the peak value appears at a position of 150 μm ² or less. The antiglare film according to claim 1 or 2, wherein the half width of the peak is larger than 10 µm ² .   The antiglare film according to any one of claims 1 to 3, wherein a reflectance in a direction deviated by 20 ° from the regular reflection angle is 0.001% or less.   The antiglare film according to any one of claims 1 to 4, wherein a 45 ° reflection sharpness measured using an optical comb having a dark portion and a bright portion width of 1.0 mm is 50% or less.   The total value of transmitted sharpness measured using four types of optical combs in which the width of the dark part and the bright part is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm is 200% or more. The anti-glare film in any one of -4.   The antiglare film according to any one of claims 1 to 6, wherein the haze is 15% or less. An image display device comprising the antiglare film according to any one of claims 1 to 7 and an image display means, wherein the antiglare film is disposed on the viewing side of the image display means.