JP2015172641A - Touch panel, display device and optical sheet, and method of selecting optical sheet and method of manufacturing optical sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel that can provide properties including an anti-glare property, and prevent glare of video light from a super-high definition display element with a pixel density of 300 ppi or more.SOLUTION: There is provided a touch panel having an optical sheet as a component member, where the optical sheet has a rugged shape on a surface, has an interval of an inclination angle of 5 to 15 degrees, which indicates half the peak value of an inclination angle distribution curve of the rugged shape, and is used for the front face of a display element with a pixel density of 300 ppi or more.

Description

  The present invention relates to a touch panel, a display device, an optical sheet, an optical sheet sorting method, and an optical sheet manufacturing method.

In recent years, mobile information terminal devices equipped with a transparent touch panel for information display and information input, which have bidirectional communication functions such as tablet PCs and smartphones, have begun to spread widely not only in Japan but around the world. Came.
A transparent touch panel has a resistive film method that is excellent in terms of cost, but it has electrostatic capacity in that gesture operations such as multi-touch are possible, and it is difficult to impair the image quality of ultra-high-definition display elements. There is an increasing demand for touch panel touch panels, particularly projection capacitive touch panels.

An anti-glare sheet having a concavo-convex structure may be provided on the surface of the touch panel for the purpose of preventing reflection of external light.
Furthermore, for the prevention of adhesion and interference fringes between members constituting the touch panel, and prevention of adhesion and interference fringes between the touch panel and the display element, the outermost surface base material, the inner base material and the rearmost surface of the touch panel An optical sheet having a concavo-convex structure may be used as a substrate or the like.

However, when an optical sheet having a concavo-convex structure such as an antiglare film is used, a phenomenon (glare) in which minute variations in luminance are seen in the image light occurs due to the concavo-convex structure, which reduces display quality. There's a problem. In particular, the glare problem has become more serious in recent high-definition display elements (pixel density of 300 ppi or more).
As techniques for preventing glare due to surface irregularities, techniques of Patent Documents 1 to 9 have been proposed.

Japanese Patent Laid-Open No. 11-305010 JP 2002-267818 A JP 2009-288650 A JP 2009-86410 A JP 2009-128393 A JP 2002-196117 A International Patent Publication No. 2007/11126 JP 2008-158536 A JP 2011-253106 A

Patent documents 1 and 2 improve glare by giving internal haze. However, an ultra-high-definition display element having a pixel density of 300 ppi or more tends to be more glaring. If an attempt is made to suppress the glaring only by the internal noise, the internal noise must be further increased. Also, when the internal haze is large, the resolution tends to deteriorate, but this tendency is greater in the ultra-high definition display element. Therefore, even if attention is paid only to the inside as in Patent Documents 1 and 2, an optical sheet suitable for an ultrahigh-definition display element having a pixel density of 300 ppi or more cannot be obtained.
Patent Documents 3 to 9 provide anti-glare properties and improve glare by designing the surface shape of the optical sheet into a specific shape. However, even the techniques of Patent Documents 3 to 9 cannot prevent glare in an ultra-high-definition display element having a pixel density of 300 ppi or more.

  The present invention has been made under such circumstances, and a touch panel, a display device, and an optical sheet that can prevent glare of image light of an ultra-high-definition display element having a pixel density of 300 ppi or more even when having an uneven structure. The purpose is to provide. The present invention also provides an optical sheet selection method and manufacturing method for preventing glare of image light of an ultra-high definition display element having a pixel density of 300 ppi or more.

In order to solve the above-mentioned problems, the present inventors have intensively studied the surface shape of an optical sheet that prevents glare. First, it is considered that the glare is caused by distortion of the transmitted light due to the uneven shape when the image light passes through the optical sheet having surface unevenness. For this reason, conventionally, in order to prevent glare, as in Patent Documents 3 to 9, a design was made to reduce the degree of unevenness by lowering the inclination angle of the unevenness. However, in these designs, even if it was possible to prevent glare of a display element having a low pixel density, glare of an ultra-high-definition display element having a pixel density of 300 ppi or more could not be prevented.
The present inventors have further researched and surprisingly found that, on the contrary, if the degree of unevenness is increased to a certain level, glare tends to be prevented. However, it may not be possible to prevent glare simply by increasing the degree of unevenness, and if the degree of unevenness is too strong, it may adversely affect optical properties other than glare. Repeatedly, the present invention has been completed.

That is, the present invention provides the following touch panel, display device and optical sheet of [1] to [16], an optical sheet sorting method, and an optical sheet manufacturing method.
[1] A touch panel having an optical sheet as a constituent member, the optical sheet having a concavo-convex shape on a surface thereof, and an inclination angle indicating a half value of a peak value of the inclination angle distribution curve of the concavo-convex shape Is a touch panel used on the front surface of a display element having an interval of 5 to 15 degrees and a pixel density of 300 ppi or more.
[2] The touch panel according to [1], wherein a ratio of an inclination angle of 0 to 1.25 degrees in an inclination angle of the uneven shape is 20% or less in terms of a cumulative percentage.
[3] The touch panel according to [1] or [2], wherein an inclination angle indicating a peak value of the inclination angle distribution curve is 2 to 8 degrees.
[4] The touch panel according to any one of [1] to [3], wherein an inclination angle indicating an inflection point in a plus direction from an inclination angle indicating a peak value of the inclination angle distribution curve is 4 to 15 degrees.
[5] The touch panel according to any one of [1] to [4], wherein a skewness of the uneven angle distribution of the uneven shape is 0 to 1.5.
[6] The touch panel according to any one of the above [1] to [5], wherein the concavo-convex inclination angle distribution has a kurtosis of 1.5 to 6.
[7] The touch panel according to any one of [1] to [6], wherein a ratio of an inclination angle of 15 degrees or more in the inclination angle of the uneven shape is 3% or less in cumulative percentage.
[8] A display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, wherein the optical sheet has a concavo-convex shape on the surface, and a peak of the inclination angle distribution curve of the concavo-convex shape The display device in which the interval of the inclination angle indicating the value of 1/2 of the value is 5 to 15 degrees.

[9] An optical sheet having a concavo-convex shape on the surface, wherein an inclination angle interval indicating a half value of a peak value of the concavo-convex inclination angle distribution curve is 5 to 15 degrees, and a pixel density of 300 ppi or more An optical sheet used on the front surface of the display element.
[10] The optical sheet according to [9], wherein a ratio of an inclination angle of 0 to 1.25 degrees in an inclination angle of the uneven shape is 20% or less in cumulative percentage.
[11] The optical sheet according to [9] or [10], wherein an inclination angle indicating a peak value of the inclination angle distribution curve is 2 to 8 degrees.
[12] The optical sheet according to any one of [9] to [11], wherein an inclination angle indicating an inflection point in the plus direction from an inclination angle indicating a peak value of the inclination angle distribution curve is 4 to 15 degrees.
[13] The optical sheet according to any one of [9] to [12], wherein the skewness distribution of the uneven shape has a skewness of 0 to 1.5.
[14] The optical sheet according to any one of [9] to [13], wherein the kurtosis of the concavo-convex-shaped inclination angle distribution is 1.5 to 6.

[15] A method for selecting an optical sheet having a concavo-convex shape on the surface, wherein the inclination angle of the concavo-convex shape of the optical sheet is measured, and a value half of the peak value of the inclination angle distribution curve obtained from the measurement result is A method for selecting an optical sheet used for the front surface of a display element having a pixel density of 300 ppi or more, wherein an optical sheet having an inclination angle interval of 5 to 15 degrees is selected as an optical sheet.
[16] A method for manufacturing an optical sheet having a concavo-convex shape on the surface, wherein the interval between the inclination angles indicating the half value of the peak value of the inclination angle distribution curve of the concavo-convex shape of the optical sheet is 5 to 15 degrees. The manufacturing method of the optical sheet used for the front surface of the display element of the pixel density of 300 ppi or more manufactured.

The touch panel, the display device, and the optical sheet of the present invention can impart various characteristics such as anti-glare properties and can prevent glare of image light of an ultra-high-definition display element having a pixel density of 300 ppi or more. In particular, when the uneven surface of the optical sheet is used facing the viewer side, reflection of external light can be suppressed even in a bright outdoor environment, and high antiglare properties can be imparted.
In addition, the optical sheet evaluation method of the present invention can perform glare evaluation without incorporating an optical sheet into a display device, and can efficiently control the quality of the optical sheet. In addition, the method for producing an optical sheet of the present invention efficiently produces an optical sheet that can impart various properties such as anti-glare properties and can prevent glare of image light of an ultrahigh-definition display element having a pixel density of 300 ppi or more. be able to.

It is sectional drawing which shows one Embodiment of the resistive film type touch panel of this invention. It is sectional drawing which shows one Embodiment of the capacitive touch panel of this invention. It is a figure which shows the uneven | corrugated shaped inclination-angle distribution curve of the optical sheet of Example 1. FIG. It is a figure which shows the inclination-angle distribution curve of the uneven | corrugated shape of the optical sheet of Example 2. FIG. It is a figure which shows the inclination-angle distribution curve of the uneven | corrugated shape of the optical sheet of Example 3. FIG. It is a figure which shows the uneven | corrugated shaped inclination-angle distribution curve of the optical sheet of the comparative example 1. It is a figure which shows the uneven | corrugated shaped inclination-angle distribution curve of the optical sheet of the comparative example 2. It is a figure which shows the uneven | corrugated shaped inclination-angle distribution curve of the optical sheet of the comparative example 3. It is a figure which shows the inclination-angle distribution curve of the uneven | corrugated shape of the optical sheet of the comparative example 4. 2 is a scanning transmission electron micrograph (STEM) showing a cross section of the optical sheet of Example 1. FIG.

Embodiments of the present invention will be described below.
[Touch panel]
The touch panel of the present invention is a touch panel having an optical sheet as a constituent member, and the optical sheet has a concavo-convex shape on the surface, and has a value that is ½ of the peak value of the inclination angle distribution curve of the concavo-convex shape. The interval between the two tilt angles shown is 5 to 15 degrees, and is used for the front surface of a display element having a pixel density of 300 ppi or more.

Examples of the touch panel include a capacitive touch panel, a resistive touch panel, an optical touch panel, an ultrasonic touch panel, and an electromagnetic induction touch panel. These touch panels have a base material such as a glass base material and a plastic film base material, and the surface on the base material has an uneven shape for imparting various characteristics such as antiglare property, adhesion prevention and interference fringe prevention. May be formed. The touch panel of the present invention uses an optical sheet to be described later as a substrate having an uneven shape on such a surface.
In addition, the optical sheet described later can impart good anti-glare properties even in a bright environment outdoors, and can also prevent glare and a decrease in resolution. Therefore, the touch panel of the present invention is preferably used so that the uneven surface of the optical sheet described later faces the operator side (the side opposite to the display element). A portable information terminal typified by a smartphone in recent years has an ultra-high-definition display element and performs a touch panel operation outdoors, so that the uneven surface of an optical sheet, which will be described later, faces the operator side. Is very useful.

  As shown in FIG. 1, the resistive touch panel 1 has a basic configuration in which a conductive film 12 of a pair of upper and lower transparent substrates 11 having a conductive film 12 is arranged via a spacer 13 so as to face each other. A circuit (not shown) is connected. In the case of a resistive film type touch panel, it is preferable to use an optical sheet described later as the upper transparent substrate and / or the lower transparent substrate. In addition, the upper transparent substrate and the lower transparent substrate may use an optical sheet described later as one base material as a multilayer structure including two or more base materials.

The optical sheet in the resistive film type touch panel, for example, uses an optical sheet, which will be described later, as the upper transparent substrate, and if the concave and convex surface of the optical sheet faces away from the lower transparent substrate, it is highly advanced in the resistive film type touch panel. Anti-glare properties can be imparted, glare of an ultra-high-definition display element can be prevented, and further, a decrease in resolution of the ultra-high-definition display element can be prevented. In addition, this method is preferable in that it can make it difficult to see the scratches on the surface of the touch panel, the conductive film, etc., and can contribute to the improvement of the yield.
In addition, by using an optical sheet, which will be described later, as the lower transparent substrate of the resistive touch panel, and by making the uneven surface of the optical sheet face the upper transparent substrate side, the reflection of the surface of the lower electrode is suppressed, and the The glare of the fine display element can be prevented. Further, in the case of this usage, it is possible to prevent the upper and lower conductive films from adhering to each other at the time of operation, and it is possible to prevent the occurrence of interference fringes due to the proximity of the upper and lower conductive films.
In addition, when an optical sheet described later is used as the upper transparent substrate and / or the lower transparent substrate so that the concavo-convex surface faces the side opposite to the upper electrode, it is preferable in that adhesion and interference fringes can be prevented.

The capacitive touch panel includes a surface type and a projection type, and a projection type is often used. A projected capacitive touch panel is formed by connecting a circuit to a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X electrode are arranged via an insulator. The basic structure will be described more specifically. A mode in which X electrodes and Y electrodes are formed on separate surfaces of a single transparent substrate, and an X electrode, an insulator layer, and a Y electrode are formed in this order on the transparent substrate. As shown in FIG. 2, an X electrode 22 is formed on a transparent substrate 21, a Y electrode 23 is formed on another transparent substrate 21, and the layers are laminated via an adhesive layer 24 or the like. It is done. Moreover, the aspect which laminate | stacks another transparent substrate in these basic aspects is mentioned.
In the case of a capacitive touch panel, it is preferable to use an optical sheet described later for at least one of the transparent substrates. In addition, the transparent substrate may use an optical sheet to be described later as one base material as a multilayer structure including two or more base materials.

In the case where the capacitive touch panel has another transparent substrate on the basic aspect described above, an optical sheet to be described later is used as the other transparent substrate, and the uneven surface of the optical sheet is opposite to the basic aspect side. When the concave-convex surface is directed to the operator side, it is possible to impart a high degree of antiglare to the capacitive touch panel and to prevent glare of the ultra-high-definition display element. Further, it is possible to prevent a decrease in resolution of the ultra-high definition display element. In addition, this usage is preferable in that it is difficult to see the scratches on the surface of the touch panel, the conductive film, and the like, and the shape of the electrode pattern.
Further, in the case where the capacitive touch panel has a configuration in which an X electrode is formed on a transparent substrate, a Y electrode is formed on another transparent substrate, and laminated via an adhesive or the like, it will be described later as at least one transparent substrate. The same effect as described above can be obtained even when the optical sheet including the optical sheet is used and the concave / convex surface of the optical sheet faces the side opposite to the basic aspect side and the concave / convex surface is directed to the operator side. Can do.
In addition, when the optical sheet mentioned later is used as a transparent substrate of an electrostatic capacitance type touch panel so that an uneven surface may face the opposite side to an operator, it is suitable at the point which can prevent adhesion and an interference fringe.

(Optical sheet)
The optical sheet has a concavo-convex shape on the surface, and an inclination angle interval (hereinafter also referred to as “full width at half maximum”) indicating a half value of the peak value of the concavo-convex inclination angle distribution curve is 5. That is ~ 15 degrees. When the full width at half maximum is less than 5 degrees, the concavo-convex shape in which the inclination angle is concentrated in a certain narrow range is likely to cause glare. In addition, when the full width at half maximum exceeds 15 degrees, the ratio of the steep inclination angle exceeding 15 degrees increases, which tends to cause whitening and a decrease in resolution, and the optical sheet is used as an antiglare sheet. The contrast tends to decrease.
The full width at half maximum is preferably 5 to 12 degrees, more preferably 6 to 10 degrees.

  Note that the inclination angle distribution curve of the present invention is an approximate curve obtained by linear interpolation of values in each section of a histogram of inclination angle distribution. Further, the value (frequency) of each section is assigned to the position of the center angle of each section of the histogram. For example, when a certain section of the histogram is set to X degrees to Y degrees, the value (frequency) of the section is assigned to a position of (X + Y) / 2 degrees. In addition, it is preferable that the histogram serving as the basis of the inclination angle distribution curve has a sufficiently narrow section width in order to accurately reflect the inclination angle distribution. If the width of the section is 0.5 degrees or less, the inclination angle distribution state can be accurately reflected. On the other hand, when the width of the section is too narrow, the influence of noise increases. For this reason, the width of the section is preferably 0.1 to 0.5 degrees. For example, in Example 1 described later, the section width is set to 0.425 degrees.

Conventionally, in order to prevent glare, a design was made to reduce the degree of unevenness by lowering the inclination angle, but in the present invention, conversely, the presence of unevenness with a high inclination angle prevents glare. . That is, the full width at half maximum of 5 degrees or more indicates the presence of irregularities with a high inclination angle, the presence of various inclination angles, and the fact that there are few areas close to flat. . The optical sheet used in the touch panel of the present invention is considered to be able to prevent glare by having a slope with a high tilt angle, having various tilt angles, and having an uneven shape with few flat areas. . (To be exact, it is considered that some glare occurs in the present invention. However, in the present invention, the surface of the optical sheet is reduced in the boundary between the uneven portion and the substantially smooth portion, and various inclination angles are used. It is thought that the glare is averaged and made inconspicuous by the presence of
In addition, the optical sheet used in the touch panel of the present invention can improve the antiglare property due to the uneven shape, so that it is not necessary to increase the internal noise more than necessary, thereby preventing the resolution of the ultra-high-definition display element from being lowered. be able to. Further, since the uneven shape has few regions close to flat and has various inclination angles, it can provide high antiglare properties. In addition, the conventional optical sheet prevents glare by weakening the degree of unevenness, and has a flat portion between the particles forming the unevenness, so that the shape is completely different from the optical sheet of the present invention. It is.

  The touch panel of this invention can make glare prevention property more favorable, providing various characteristics, such as anti-glare property. In particular, when an optical sheet is arranged on the operator side of the touch panel and used as an antiglare sheet, it is preferable in that it is easy to impart antiglare properties while suppressing a decrease in contrast. That is, since the optical sheet used in the present invention has a specific concavo-convex shape, it imparts an antiglare property capable of withstanding an outdoor bright environment by suppressing reflection in the regular reflection direction, and Further, it is possible to prevent a decrease in contrast by suppressing the angle of diffuse reflection from being too wide. Moreover, it can also prevent that the resolution of an ultra-high-definition display element falls by suppressing that the angle of a diffuse reflection is spread too much.

  The uneven shape of the optical sheet is preferably a shape that gradually decreases in the ± angle direction from the peak value of the inclination angle distribution curve. Since the optical sheet having the shape has two inclination angles indicating a half value of the peak value of the uneven inclination angle distribution curve, the interval between the two points is the full width at half maximum. In the case where the concave / convex shape slope angle distribution curve of the optical sheet gradually increases from the peak value and then gradually decreases again, there are two inclination angles indicating 1/2 of the peak value of the inclination angle distribution curve. May be exceeded. In such a case, the full width at half maximum is defined as the interval between the angle indicating ½ first visited in the + direction from the peak value and the angle indicating ½ first visited in the − direction from the peak value.

  FIGS. 3-9 is the figure which normalized the inclination angle distribution curve of the uneven | corrugated shape of the optical sheet of Examples 1-3 and Comparative Examples 1-4 as the peak value of 100, respectively. 3 to 9 corresponds to the full width at half maximum of the optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4 when the frequency is 50. For example, the full width at half maximum of the optical sheet of Example 3 in FIG. 5 is 5.2 degrees, which is an interval of inclination angles (0.9 degrees and 6.1 degrees) indicating a frequency of 50.

The inclination angle distribution of the uneven shape of the optical sheet is obtained by measurement with a contact surface roughness meter or a non-contact surface roughness meter (for example, an interference microscope, a confocal microscope, an atomic force microscope, etc.). It can be calculated from the roughness surface. The data of the three-dimensional roughness curved surface is represented by points arranged in a grid pattern at intervals d on a reference plane (the horizontal direction is the x-axis and the vertical direction is the y-axis) and the height at the position of the point. Assuming that the height at the position of the i-th point in the x-axis direction and the j-th point in the y-axis direction (hereinafter referred to as (i, j)) is Z _{i, j} , x at any position (i, j) The inclination Sx in the x-axis direction with respect to the axis and the inclination Sy in the y-axis direction with respect to the y-axis are calculated as follows.
Sx = (Z _{i + 1, j} −Z _{i−1, j} ) / 2d
Sy = (Z _{i, j + 1} −Z _{i, j−1} ) / 2d
Furthermore, the inclination St with respect to the reference plane at (i, j) is calculated as the following equation (1).
The tilt angle at (i, j) is calculated as tan ⁻¹ (St). The inclination angle distribution of the three-dimensional roughness curved surface is calculated by performing the above calculation for each point. From the calculated histogram of the tilt angle distribution data, a tilt angle distribution curve is created by the method described above, and a tilt angle indicating the full width at half maximum and a peak value described later can be calculated from the curve.
In addition, the below-mentioned three-dimensional average inclination angle, inflection point, skewness, and kurtosis can be calculated by the method described in the examples.
The three-dimensional roughness curved surface is preferably measured using an interference microscope for simplicity. Examples of such an interference microscope include “New View” series manufactured by Zygo.

In the optical sheet, the ratio of the inclination angle of 0 to 5 degrees in the uneven inclination angle is preferably 40 to 80%, more preferably 45 to 75% in terms of cumulative percentage. By setting the ratio to 40% or more, the ratio of unevenness with an inclination angle exceeding 5 degrees can be reduced, and whitening and a decrease in contrast can be prevented. Further, by setting the ratio to 80% or less, glare can be more easily prevented and antiglare properties that can withstand bright outdoor environments can be imparted.
Further, from the viewpoint of making the antiglare property better, the proportion of the inclination angle of 0 to 1.25 degrees in the inclination angle of the uneven shape is preferably 20% or less in terms of cumulative percentage, and is 15% or less. Is more preferable and 12% or less is further preferable.

  In the optical sheet, the ratio of the inclination angle exceeding 15 degrees in the uneven inclination angle is preferably 3% or less, more preferably 2% or less, and more preferably 1.5% or less in terms of cumulative percentage. Further preferred. By setting the ratio to 3% or less, whitening, a decrease in resolution, and a decrease in contrast can be easily prevented.

The optical sheet preferably has an uneven three-dimensional average inclination angle (θa _3D ) of 3.0 to 9.0 degrees, more preferably 4.0 to 8.0 degrees, and 4.5 to More preferably, it is 7.0 degrees. By setting θa _3D to 3.0 degrees or more, it is possible to easily impart various characteristics such as anti-glare properties. Further, by setting θa _3D to 9.0 degrees or less, whitening, a reduction in resolution, and a reduction in contrast can be easily prevented.

  The optical sheet preferably has an inclination angle indicating a peak value of an inclination angle distribution curve of 2 to 8 degrees, more preferably 2.1 to 7 degrees, and further preferably 2.1 to 6 degrees. preferable. By setting the angle to 2 degrees or more, glare can be easily prevented while imparting various properties such as anti-glare properties. Further, by setting the angle to 8 degrees or less, it is possible to easily prevent whitening, a decrease in resolution, and a decrease in contrast.

The optical sheet has an inclination angle indicating the inflection point in the plus direction from the inclination angle indicating the peak value of the inclination angle distribution curve (hereinafter sometimes referred to as “inclination angle indicating the inflection point in the plus direction”). It is preferably ˜15 degrees, more preferably 5 to 12 degrees, still more preferably 5.5 to 10 degrees, and even more preferably 6 to 8.5 degrees. That the angle is 4.0 degrees or more means that the uneven surface has various inclination angles without concentrating the inclination in an angle region having a low inclination angle. Thus, it is thought that glare can be prevented more by having the various tilt angles without concentrating the tilt in the angle region where the tilt angle is low. In addition, by setting the angle to 4 degrees or more, various characteristics such as anti-glare property can be easily improved due to the presence of a slope having a high inclination angle. Further, by setting the angle to 15 degrees or less, whitening, resolution reduction, and contrast reduction can be easily prevented.
In addition, the optical sheet has a difference between the inclination angle indicating the inflection point and the inclination angle indicating the peak value ([inclination indicating the inflection point in the plus direction) from the viewpoint of improving the effect of the above-described inflection point. Angle]-[tilt angle showing peak value]) is preferably 2.2 to 10 degrees, more preferably 2.5 to 9 degrees, and even more preferably 2.8 to 8 degrees. More preferably, it is 2.8 to 5 degrees.

  The optical sheet preferably has a distorted inclination angle distribution with a skewness of 0 to 1.5, more preferably 0 to 1.4, and even more preferably 0 to 1.2. By setting the skewness to 0 to 1.5, adverse effects caused by the inclination angle distribution being moderately biased to a region having a small inclination angle and being excessively biased to a region having a large inclination angle (whitening, lowering of resolution and lowering of contrast) In addition, it is possible to easily prevent adverse effects (occurrence of glare) caused by being too biased in a region having a small inclination angle.

  The optical sheet preferably has a kurtosis of an uneven inclination angle distribution of 1.5 to 6, more preferably 2 to 6, and further preferably 2.5 to 6. By setting the kurtosis to 1.5 or more, the skirt of the inclination angle distribution is widened, the unevenness has various inclination angles, and glare can be further prevented. Further, by setting the kurtosis to 6 or less, it is possible to prevent the inclination from being concentrated in an extremely narrow angle range in the vicinity of the peak value of the frequency, to further prevent glare, and to reduce the flat angle (peak value). (Angle below) side hem is reduced to improve anti-glare property, and steep angle (angle above peak value) side is reduced to prevent whitening, resolution reduction and contrast reduction. It can be done easily.

  The optical sheet preferably has a total light transmittance (JIS K7361-1: 1997) of 80% or more, more preferably 85% or more, and further preferably 90% or more.

The optical sheet preferably has a haze (JIS K7136: 2000) of 25 to 60%, more preferably 30 to 60%, and still more preferably 30 to 50%. By setting the haze to 25% or more, it is possible to impart antiglare properties and make it difficult to see the shape and scratches of the electrode. Further, by setting the haze to 60% or less, it is possible to prevent a decrease in resolution of an ultra-high-definition display element and to easily prevent a decrease in contrast.
When haze is divided into surface haze (Hs) and internal haze (Hi), the surface haze is preferably 20 to 50%, more preferably 20 to 45%, and more preferably 25 to 40%. More preferably. By setting the surface haze to 20% or more, it is possible to improve the antiglare property even in bright usage environments such as outdoors, and to make it difficult to see the shape and scratches of the electrode. It is easy to prevent a decrease in resolution and a decrease in resolution.
Further, the internal haze is preferably 5 to 30%, more preferably 5 to 25%, and further preferably 10 to 18%. By setting the internal haze to 5% or more, it is easy to prevent glare due to a synergistic effect with the surface unevenness, and by setting the internal haze to 30% or less, it is possible to prevent the resolution of the ultrahigh-definition display element from being lowered.
In addition, the ratio of surface haze to internal haze (Hs / Hi) is preferably 1.0 to 5.0 from the viewpoint of the balance between the above-described surface haze and internal haze effects, and is preferably 2.0 to 2.0. More preferably, it is -5.0, and it is further more preferable that it is 2.5-4.5.
The surface haze and internal haze can be determined by, for example, the method described in Examples.

  The optical sheet has a width of 2 mm, 1 mm, 0.5 mm, and 0.125 mm using an image sharpness measuring device defined in JIS K7105: 1981 from the viewpoint of resolution and the difficulty of seeing electrode shapes and scratches. The sum of the four types of transmitted image clarity through the optical comb is preferably 100% or less, more preferably more than 20% and 80% or less.

  The arithmetic average roughness Ra of the uneven shape of the optical sheet is preferably 0.20 to 0.70 μm, and more preferably 0.25 to 0.50 μm. By setting Ra to 0.20 μm or more, glare can be easily prevented, antiglare property, adhesion prevention property and interference fringe prevention property can be easily improved, and the shape and scratches of the electrode can be made difficult to see. . In addition, when Ra is set to 0.70 μm or less, it is possible to easily prevent a decrease in resolution and contrast. Ra and Rz and Smp described later are values with a cutoff value of 0.8 mm.

In the present invention, Ra is a two-dimensional roughness parameter Ra described in JIS B0601: 1994, and is expanded three-dimensionally. Orthogonal coordinate axes X and Y axes are placed on a reference plane, and a roughness curved surface is obtained. If Z (x, y) and the size of the reference plane are Lx and Ly, the following equation (2) is calculated.
A = Lx × Ly
Further, when the above Z _{i, j} is used, it is calculated by the following equation (3).
N: All points

The ten-point average roughness Rz of the uneven shape of the optical sheet is preferably 1.00 to 3.50 μm, and more preferably 1.20 to 3.00 μm. By setting Rz to 1.00 μm or more, it is possible to easily prevent glare, to easily improve antiglare property, adhesion prevention property and interference fringe prevention property, and to make it difficult to see the shape and scratches of the electrode. . Further, by setting Rz to 3.50 μm or less, there is no convex portion having an extremely high altitude, so that it is possible to easily prevent a decrease in resolution and contrast.
Moreover, from the viewpoint of making it easier to obtain the above-described effects of Ra and Rz, the ratio [Rz / Ra] of Rz and Ra is preferably 6.0 or less, and preferably 4.0 to 6.0. Is more preferable, and it is further more preferable that it is 4.5-5.7.

  In the present invention, Rz is obtained by extending Rz, which is a two-dimensional roughness parameter described in JIS B0601: 1994, to three dimensions. A large number of straight lines that pass through the center of the reference surface are placed on the reference surface in a 360-degree radial pattern so as to cover the entire area, and a cross-sectional curve that is cut based on each straight line is obtained from a three-dimensional roughness surface. The point average roughness (the sum of the average of the mountain heights up to the fifth highest from the highest peak and the average of the valley depths up to the fifth deepest from the deepest valley bottom) is obtained. It is calculated by averaging the top 50% of the large number of ten-point average roughness thus obtained.

  The average peak spacing Smp of the irregularities of the optical sheet is preferably 25 to 100 μm, more preferably 30 to 80 μm, and even more preferably 30 to 70 μm. By making the full width at half maximum of the inclination angle distribution curve within the range of the present invention and making Smp into the above range, it is possible to form an uneven shape that is neither too loose nor too steep, making it easy to prevent glare and anti-glare. Performance, adhesion prevention, interference fringe prevention, electrode shape and scratch invisibility, resolution reduction prevention, and whitening prevention can be easily exhibited.

Smp is obtained as follows. Smp, where Ps is the number of ridges of a three-dimensional roughness surface that is higher than the reference plane and surrounded by one area, and A is the area of the entire measurement area (reference plane) Is calculated by the following equation (4).
The Ra, Rz and Smp can be calculated by the measurement / analysis application software “MetroPro” attached to the above-described interference microscope “New View” series.

The optical sheet described above can be used without any particular limitation as long as it has the above-described uneven shape on at least one surface and has optical transparency. Moreover, although the uneven | corrugated shape mentioned above may have on both surfaces of an optical sheet, it has the uneven | corrugated shape mentioned above on one side from a viewpoint of handleability and image visibility (resolution, whitening), and the other surface is It is preferably substantially smooth (Ra 0.02 μm or less).
In addition, the optical sheet may be a single layer of a concavo-convex layer or a multilayer having a concavo-convex layer on a transparent substrate. From the viewpoint of ease of handling and manufacturing, a configuration having an uneven layer on a transparent substrate is preferable.

  Examples of the method for forming irregularities include 1) a method using an embossing roll, 2) an etching treatment, 3) molding by a mold, 4) formation of a coating film by coating, and the like. Among these methods, the molding by the mold 3) is preferable from the viewpoint of reproducibility of the uneven shape, and the formation of the coating film by the coating of 4) is preferable from the viewpoint of productivity and a variety of products.

  Molding with a mold is performed by producing a mold having a shape complementary to the concave and convex surface, pouring a material constituting the concave and convex layer such as a polymer resin or glass into the mold and curing it, and then removing the mold from the mold. be able to. When a transparent substrate is used, a polymer resin or the like is poured into a mold, and after overlaying the transparent substrate on the mold, the polymer resin or the like is cured, and the entire transparent substrate is taken out from the mold. be able to.

The coating film is formed by coating by applying a coating solution for forming a concavo-convex layer containing a resin component and translucent particles onto a transparent substrate by a known coating method such as gravure coating or bar coating. It can be formed by drying and curing. In order to make the concavo-convex shape in the above-described range, it is preferable to include inorganic ultrafine particles in the concavo-convex layer forming coating solution.
FIG. 10 is a scanning-type transmission showing a cross-section of the concavo-convex layer of the optical sheet of Example 1 formed by coating a concavo-convex layer-forming coating liquid containing a binder resin, translucent particles and inorganic ultrafine particles. It is an electron micrograph (STEM).
Usually, the surface of the concavo-convex layer is substantially smooth at the places where the light-transmitting particles are not present, but the concavo-convex layer of FIG. 10 has a gentle slope at the places where the translucent particles are not present. This is presumably because the inorganic ultrafine particles affect the thixotropy of the coating solution and the drying characteristics of the solvent, and normal leveling does not occur. As described above, it is considered that a gentle slope is formed even in a portion where the translucent particles are not present, so that a substantially smooth portion is eliminated as much as possible in the concavo-convex layer, and the full width at half maximum and the like are easily within the scope of the present invention.

Moreover, it is thought that the uneven | corrugated layer of FIG. 10 can make it easy to make the full width at half maximum etc. into the range mentioned above for the reasons of (1)-(3) below.
(1) A slightly steep slope where the translucent particles are present and a gentle slope where the translucent particles are not present are mixed to form an uneven shape with random slopes.
(2) Normally, the shape of the concavo-convex layer of the translucent particle existing near the surface of the concavo-convex layer is a convex shape along the shape of the translucent particle. The shape is not in line with the shape of the light-sensitive particles. As described above, the shape of the translucent particles existing in the vicinity of the surface of the uneven layer is not sufficiently reflected in the surface shape of the uneven layer, so that there are few steep unevenness.
(3) In the concavo-convex layer in FIG. 4, the translucent particles are both dispersed and aggregated. This is probably because the inorganic ultrafine particles have an effect on the thixotropic properties of the coating solution and the affinity between the translucent particles. As described above, the presence of both dispersion and agglomeration results in a random surface shape with many variations in the uneven shape.

As the translucent particles, both translucent organic particles and translucent inorganic particles can be used. The translucent particles include shapes such as a spherical shape, a disc shape, a rugby ball shape, and an indeterminate shape, and also include hollow particles, porous particles, solid particles, and the like having these shapes. Among these, spherical solid particles are preferable from the viewpoint of preventing glare.
Translucent organic particles include polymethyl methacrylate, polyacryl-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluororesin, and polyester resin. The particle | grains which become are mentioned.
Examples of the translucent inorganic particles include particles made of silica, alumina, zirconia, titania and the like.
Among the above-described translucent particles, translucent organic particles are preferable from the viewpoint of ease of dispersion control, and among them, polyacryl-styrene copolymer particles are preferable. Since the polyacryl-styrene copolymer particles can easily control the refractive index and the degree of hydrophilicity / hydrophobicity, they are good in that the internal haze and the aggregation / dispersion can be easily controlled.

From the viewpoint of making it easy to obtain the above-described uneven shape, the translucent particles preferably have an average particle diameter of 2 to 10 μm, and more preferably 3 to 8 μm. The average particle diameter of the translucent particles can be calculated by the Coulter counter method.
In addition, the ratio of the average particle diameter of the translucent particles to the thickness of the concavo-convex layer (average particle diameter of the translucent particles / thickness of the concavo-convex layer) is 0.5 to 1.0 is preferable, and 0.6 to 0.9 is more preferable.

  The content of the translucent particles is preferably 2 to 25% by mass, and 5 to 20% by mass in the total solid content forming the uneven layer, from the viewpoint of easily obtaining the above-described uneven shape. More preferred.

Examples of the inorganic ultrafine particles include ultrafine particles made of silica, alumina, zirconia, titania and the like. Among these, silica ultrafine particles are preferable from the viewpoint of transparency.
The inorganic ultrafine particles preferably have an average primary particle diameter of 1 to 25 nm, more preferably 5 to 20 nm, from the viewpoint of easily obtaining the above-described uneven shape. The average primary particle diameter of the inorganic ultrafine particles can be calculated by converting from the specific surface area measured by the BET nitrogen adsorption method (according to JIS Z8830).

The inorganic ultrafine particles are preferably reactive inorganic ultrafine particles into which a reactive group has been introduced by surface treatment. By introducing a reactive group, it becomes possible to contain a large amount of inorganic ultrafine particles in the concavo-convex layer, and the above concavo-convex shape can be easily obtained.
As the reactive group, a polymerizable unsaturated group is suitably used, preferably a photocurable unsaturated group, and particularly preferably an ionizing radiation curable unsaturated group. Specific examples thereof include (meth) acryloyl groups, (meth) acryloyloxy groups, ethylenically unsaturated bonds such as vinyl groups and allyl groups, and epoxy groups.
Examples of such reactive inorganic ultrafine particles include inorganic ultrafine particles surface-treated with a silane coupling agent. In order to treat the surface of the inorganic ultrafine particles with a silane coupling agent, the inorganic ultrafine particles are sprayed with a silane coupling agent, or after the inorganic ultrafine particles are dispersed in a solvent, the silane coupling agent is added and reacted. Examples include a wet method.

The content of the inorganic ultrafine particles is preferably 10 to 90% by mass, more preferably 20 to 70% by mass, and more preferably 35 to 50% by mass in the total solid content forming the uneven layer. Further preferred. By setting it as the said range, the uneven | corrugated shape mentioned above can be obtained easily by control of leveling property and suppression of the polymerization shrinkage | contraction of an uneven | corrugated layer.
Further, the ratio of the content of the translucent particles and the inorganic ultrafine particles in the concavo-convex layer (the content of the translucent particles / the content of the inorganic ultrafine particles) is from the viewpoint of easily obtaining the above concavo-convex shape. It is preferably 1 to 0.4, and more preferably 0.2 to 0.3.

  The resin component of the uneven layer preferably includes a thermosetting resin composition or an ionizing radiation curable resin composition, and more preferably includes an ionizing radiation curable resin composition from the viewpoint of improving mechanical strength. Of these, it is more preferable to include an ultraviolet curable resin composition.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, an epoxy group, and an oxetanyl group. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenic unsaturated bond groups is more preferable, and among them, having two or more ethylenically unsaturated bond groups, Polyfunctional (meth) acrylate compounds are more preferred. As the polyfunctional (meth) acrylate compound, any of a monomer and an oligomer can be used.
The ionizing radiation means an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can be used.

Among the polyfunctional (meth) acrylate compounds, bifunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, 1,6-hexane. Examples thereof include diol diacrylate.
Examples of the tri- or higher functional (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Examples include pentaerythritol tetra (meth) acrylate and isocyanuric acid-modified tri (meth) acrylate.
The (meth) acrylate-based monomer may be modified by partially modifying the molecular skeleton, and is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like. Can also be used.

Moreover, examples of the polyfunctional (meth) acrylate oligomer include acrylate polymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate.
Urethane (meth) acrylate is obtained by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth) acrylate, for example.
A preferable epoxy (meth) acrylate is a (meth) acrylate obtained by reacting (meth) acrylic acid with a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin or the like. (Meth) acrylates obtained by reacting the above aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like with polybasic acids and (meth) acrylic acid, and bifunctional or higher functional aromatic epoxy resins, It is a (meth) acrylate obtained by reacting an alicyclic epoxy resin, an aliphatic epoxy resin or the like with a phenol and (meth) acrylic acid.
The ionizing radiation curable compounds can be used alone or in combination of two or more.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like.
These photopolymerization initiators preferably have a melting point of 100 ° C. or higher. By setting the melting point of the photopolymerization initiator to 100 ° C. or higher, the photopolymerization initiator remaining during the formation of the transparent conductive film of the touch panel or the heat of the crystallization process is sublimated, and the low resistance of the transparent conductive film is impaired. Can be prevented.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more selected may be mentioned.

  The thickness of the concavo-convex layer is preferably 2 to 10 μm and more preferably 4 to 8 μm from the viewpoint of balance between curling suppression, mechanical strength, hardness and toughness. The thickness of the concavo-convex layer can be calculated from an average value obtained by selecting 10 points in the cross-sectional photograph of the optical sheet using a scanning transmission electron microscope (STEM).

In the concavo-convex layer forming coating solution, a solvent is usually used in order to adjust the viscosity and to dissolve or disperse each component. Since the surface state of the concavo-convex layer after the coating and drying process varies depending on the type of solvent, it is preferable to select the solvent in consideration of the saturated vapor pressure of the solvent, the permeability of the solvent into the transparent substrate, and the like. Specifically, the solvent is, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons. (Cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (butanol, cyclohexanol, etc.) ), Cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), etc., and mixtures thereof may be used.
When drying of the solvent is too slow or too fast, it becomes difficult to form the uneven shape described above due to excessive or insufficient leveling properties of the uneven layer. Therefore, as a solvent, it is preferable to contain the solvent whose evaporation rate (relative evaporation rate when the evaporation rate of n-butyl acetate is set to 100) is 100 to 180% by mass or more in the total solvent. As the solvent of 50% by mass or more in the total solvent, those having an evaporation rate of 100 to 150 are more preferable.
As examples of the relative evaporation rate, toluene is 195, methyl ethyl ketone (MEK) is 465, methyl isobutyl ketone (MIBK) is 118, and propylene glycol monomethyl ether (PGME) is 68.
The type of solvent also affects the dispersibility of inorganic ultrafine particles typified by silica ultrafine particles. For example, MIBK is suitable in that it has excellent dispersibility of inorganic ultrafine particles and can easily form the above-described uneven shape.

  Further, from the viewpoint of easily obtaining the uneven shape described above, it is preferable to control the drying conditions when forming the uneven layer. The drying conditions can be adjusted by the drying temperature and the wind speed in the dryer. The specific drying temperature is preferably 30 to 120 ° C. and the drying air speed is preferably 0.2 to 50 m / s. In order to control the leveling of the concavo-convex layer according to the drying conditions, it is preferable that the irradiation with ionizing radiation is performed after drying.

  Further, from the viewpoint of making the surface unevenness moderately smooth and making it easy to obtain the above-described uneven shape, it is preferable that the uneven layer forming coating liquid contains a leveling agent. Examples of the leveling agent include a fluorine-based or silicone-based one, and a silicone-based leveling agent is preferable. The amount of the leveling agent added is preferably 0.01 to 0.5% by weight, more preferably 0.05 to 0.2% by weight, based on the total solid content of the uneven layer forming coating solution.

The transparent base material of the optical sheet is preferably provided with light transmittance, smoothness, heat resistance and excellent mechanical strength. Such transparent substrates include polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal. , Polyether ketone, polymethyl methacrylate, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP). The transparent substrate may be a laminate of two or more plastic films.
Among the above, from the viewpoint of mechanical strength and dimensional stability, polyester (polyethylene terephthalate, polyethylene naphthalate) that has been stretched, particularly biaxially stretched, is preferable. Further, TAC and acrylic are suitable from the viewpoint of light transmitting optical isotropy. Moreover, COP and polyester are suitable in that they are excellent in weather resistance. In addition, a plastic film having a retardation value of 3000 to 30000 nm or a plastic film having a quarter wavelength retardation can prevent unevenness of different colors from being observed on the display screen when an image on a liquid crystal display is observed through polarized sunglasses. This is preferable in terms of points.

The thickness of the transparent substrate is preferably 5 to 300 μm, and more preferably 30 to 200 μm.
In order to improve adhesion, the surface of the transparent substrate may be preliminarily coated with a coating called an anchor agent or a primer in addition to physical treatment such as corona discharge treatment and oxidation treatment.

  The optical sheet may have a functional layer such as an antireflection layer, an antifouling layer, or an antistatic layer on the uneven shape and / or on the surface opposite to the uneven shape. Moreover, in the case of a structure having a concavo-convex layer on a transparent base material, a functional layer may be provided between the transparent base material and the concavo-convex layer in addition to the above location.

[Display device]
The display device of the present invention is a display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, and the optical sheet has a concavo-convex shape on the surface, and an inclination angle of the concavo-convex shape The interval of the inclination angle indicating 1/2 of the peak value of the distribution curve is 5 to 15 degrees.
An ultra-high-definition display element having a pixel density of 300 ppi or more is likely to cause glare as described above, but in the present invention, various characteristics such as anti-glare properties can be obtained by using a specific optical sheet as the optical sheet having an uneven shape. Glittering can be prevented while imparting.
As the optical sheet used for the display device of the present invention, the same optical sheet as used for the touch panel of the present invention described above can be used.

Examples of the display element include a liquid crystal display element, an in-cell touch panel liquid crystal display element, an EL display element, and a plasma display element.
The in-cell touch panel liquid crystal element is a liquid crystal element in which a liquid crystal is sandwiched between two glass substrates, and a touch panel function such as a resistive film type, a capacitance type, and an optical type is incorporated therein. Examples of the liquid crystal display method of the in-cell touch panel liquid crystal element include an IPS method, a VA method, a multi-domain method, an OCB method, an STN method, and a TSTN method. In-cell touch panel liquid crystal elements are described in, for example, Japanese Patent Application Laid-Open Nos. 2011-76602 and 2011-222009.

The optical sheet can be installed on the front surface of the display element in the following order, for example.
(1) Display element / surface protective plate / optical sheet (2) Display element / optical sheet (3) Touch panel having display element / optical sheet as constituent member (4) Display element / optical sheet / surface protective plate (1) and In the case of (2), by arranging the uneven surface of the optical sheet to face the surface (so that the uneven surface faces the side opposite to the display element), it is possible to provide high anti-glare properties and prevent glare. Further, it is possible to make it difficult to see the scratches on the surface and the display element.
In the case of (3), glare can be prevented while providing various properties such as anti-glare properties by disposing the optical sheet as in the embodiment of the touch panel of the present invention described above.
In the case of (2) and (4), if the concave and convex surface of the optical sheet is arranged through the air layer so as to face the display element side, adhesion and interference fringes can be prevented and scratches generated in the display element can be prevented. It can be difficult to see.
The optical sheet used in the display device of the present invention can suppress reflection of external light even in a bright outdoor environment, and can impart high antiglare properties. Since portable information terminals represented by recent smartphones are often used outdoors, the display device of the present invention uses an optical sheet so that the uneven surface faces the viewer side (the side opposite to the display element). It is preferable.

[Optical sheet]
The optical sheet of the present invention has a concavo-convex shape on the surface, an inclination angle interval representing 5/2 of the peak value of the concavo-convex inclination angle distribution curve is 5 to 15 degrees, and a pixel density of 300 ppi or more is displayed. It is used for the front surface of the element.
Examples of the optical sheet of the present invention include the same optical sheets used for the touch panel of the present invention described above.
The optical sheet of the present invention is used on the front surface of a display element having a pixel density of 300 ppi or more to prevent glare of image light and a decrease in resolution of an ultra-high-definition display element while providing various properties such as anti-glare properties. It is preferable in that it can be performed.
In addition, the optical sheet of the present invention can suppress reflection of external light even in a bright outdoor environment, and can impart high antiglare properties. Since portable information terminals typified by recent smartphones are often used outdoors, the optical sheet of the present invention has an uneven surface on the outermost surface of the touch panel or display device on the viewer side (the side opposite to the display element). It is preferable to use so that it faces.

[Optical sheet sorting method]
The optical sheet selection method of the present invention is a method for selecting an optical sheet having a concavo-convex shape on the surface, and measures the inclination angle of the concavo-convex shape of the optical sheet, and the peak value of the inclination angle distribution curve obtained from the measurement result This is a method for selecting an optical sheet used on the front surface of a display element having a pixel density of 300 ppi or more, in which the ones having an inclination angle interval of 5 to 15 degrees indicating a value of ½ are selected.
According to the optical sheet sorting method of the present invention, an optical sheet having good antiglare property can be selected when used for an ultra-high-definition display element having a pixel density of 300 ppi or more, without incorporating an optical sheet in a display device. It is possible to efficiently control the quality of the optical sheet.

The determination condition for selecting the optical sheet is that (a) the inclination angle interval (full width at half maximum) indicating 1/2 of the peak value of the inclination angle distribution curve is 5 to 15 degrees. The determination condition of the full width at half maximum of (a) is preferably 5 to 12 degrees, and more preferably 6 to 10 degrees.
Furthermore, the optical sheet which can prevent more exact glare can be selected by making one or more chosen from conditions (b)-(h) listed below as judgment conditions. The conditions (b) to (h) are preferably two or more as determination conditions, and more preferably three or more as determination conditions.

(B) The ratio of the inclination angle of 0 to 1.25 degrees in the inclination angle of the concavo-convex shape is 20% or less as a cumulative percentage.
(C) The inclination angle indicating the peak value of the inclination angle distribution curve is 2 to 8 degrees.
(D) The inclination angle indicating the inflection point in the plus direction from the inclination angle indicating the peak value of the inclination angle distribution curve is 4 to 15 degrees.
(E) The inclination angle difference between the inflection point and the peak value ([inclination angle indicating the plus inflection point] − [inclination angle indicating the peak value]) is 2.2 to 10 degrees.
(F) The degree of skewness of the uneven inclination angle distribution is 0 to 1.5.
(G) The kurtosis of the uneven angle distribution is 1.5 to 6.
(H) The ratio of the inclination angle of 15 degrees or more in the inclination angle of the uneven shape is 3% or less in cumulative percentage.
The cumulative percentage of the condition (b) is preferably 15% or less, and more preferably 12% or less. The inclination angle indicating the peak value of the condition (c) is preferably 2.1 to 7 degrees, and more preferably 2.1 to 6 degrees. The inclination angle indicating the inflection point of the condition (d) is preferably 5 to 12 degrees, more preferably 5.5 to 10 degrees, and further preferably 6 to 8.5 degrees. The inclination angle difference between the inflection point of condition (e) and the peak value is preferably 2.5 to 9 degrees, more preferably 2.8 to 8 degrees, and 2.8 to 5 degrees. More preferably it is. The skewness of the condition (f) is preferably 0 to 1.4, more preferably 0 to 1.2. The kurtosis of the condition (g) is preferably 2 to 6, and more preferably 2.5 to 6. The cumulative percentage of the condition (h) is preferably 2% or less, and more preferably 1.5% or less.

[Optical sheet manufacturing method]
The method for producing an optical sheet according to the present invention is a method for producing an optical sheet having a concavo-convex shape on the surface, and is an inclination angle interval that indicates a value that is half the peak value of the inclination angle distribution curve of the concavo-convex shape of the optical sheet. Is an optical sheet manufacturing method used for the front surface of a display element having a pixel density of 300 ppi or higher.

In the manufacturing method of the optical sheet of the present invention, the manufacturing conditions are controlled so that (a) the inclination angle interval (full width at half maximum) representing 1/2 of the peak value of the inclination angle distribution curve is 5 to 15 degrees. It is essential to do. A preferable range of the full width at half maximum of the condition (a) is the same as that of the optical sheet selection method described above. Further, as an additional condition, it is preferable to satisfy one or more of the conditions (b) to (h) of the optical sheet selection method described above, more preferably two or more, and still more preferably three or more.
According to the method for producing an optical sheet of the present invention, it is possible to efficiently produce an optical sheet capable of imparting various properties such as anti-glare properties and preventing glare of image light of an ultrahigh-definition display element having a pixel density of 300 ppi or more. it can

The manufacturing conditions (a) to (h) are such that the unevenness layer of the optical sheet has as few as possible smooth portions as much as possible, and the entire unevenness layer has a shape that is inclined, and the entire surface has a uniform inclination. Instead, it can be controlled by mixing various inclination angles including inclinations having a large inclination angle.
The specific means for controlling the manufacturing conditions (a) to (h) may be to control the shape of the mold when the uneven layer is formed by a mold. In addition, as described above, specific means for controlling the production conditions (a) to (h) when the uneven layer is formed by coating are to use an appropriate amount of inorganic ultrafine particles and have a relative evaporation rate within a specific range. Examples include using a solvent, adjusting drying conditions such as drying temperature and wind speed, and using an appropriate amount of a leveling agent.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples. “Part” and “%” are based on mass unless otherwise specified.

1. Measurement and Evaluation of Physical Properties of Optical Sheets Physical property measurements and evaluations of optical sheets of Examples and Comparative Examples were performed as follows. The results are shown in Table 1.

[Inclination angle distribution of uneven shape of optical sheet]
On the surface opposite to the surface on which the antiglare layer (unevenness layer) of each optical sheet obtained in Examples and Comparative Examples is formed, a sample is attached to a glass plate via a transparent adhesive, Using a white interference microscope (New View 7300, manufactured by Zygo), the surface shape of the optical sheet was measured and analyzed under the following conditions. In addition, Microscope Application 8.3.2 Microscope Application was used as measurement / analysis software.
(Measurement condition)
Objective lens: 50 × Zoom: 1 × Measurement area: 414 μm × 414 μm
Resolution (interval per point): 0.44 μm
(Analysis conditions)
Removed: None
Filter: BandPass
FilterType: GaussSpline
Low wavelength: 800 μm
High wavelength: 3 μm
Remove spikes: on
Spike Height (xRMS): 2.5
Note that Low wavelength corresponds to the cutoff value λc in the roughness parameter.
Next, the above-mentioned analysis software (MetroPro ver. 8.3.2-Microscope Application) displays a Slope Map Map screen, and the histogram is displayed as nBins = 100 in the screen, and the histogram data of the three-dimensional surface inclination angle distribution is displayed. Obtained. Based on the obtained histogram data, the full width at half maximum, the cumulative percentage of the tilt angle in a specific range, the average tilt angle, the tilt angle indicating the peak value, the inflection point on the plus side from the peak value, the skewness and the kurtosis were calculated. The section width of each class angle in the histogram was not less than 0.1 degrees and not more than 0.5 degrees. The results are shown in Table 1.

In calculating the full width at half maximum and the peak value, an approximate curve (inclination angle distribution curve) was created by linear interpolation of the value of each class angle section of the obtained histogram data, and calculated from the curve.
In the calculation of the cumulative percentage of the inclination angle in the specific range, the cumulative frequency percentage for each class angle was obtained from the obtained histogram data and calculated by linear interpolation.
In calculating the inflection point, for each class angle of the obtained histogram data, find the value obtained by subtracting the frequency one level before that class (the smaller angle) from the class frequency, and the value is negative. The inflection point is the class angle when the absolute value becomes the maximum.
The three-dimensional average inclination angle, skewness, and kurtosis from the histogram data of the uneven inclination angle distribution were calculated as follows.

When _i Representative angle of the i-th class of the histogram data theta, the frequency and f _i, the three-dimensional average inclination angle m is calculated by the following equation (5).
Here, N is the total number of data and is calculated by the following equation (6).
The skewness Sk and the kurtosis Ku are calculated by the following formulas (7) and (8).
Here, sd is a standard deviation and is calculated by the following equation (6).

[Ra, Rz, Smp of optical sheet]
“Ra” and “SRz” are displayed on the Surface Map screen using the surface shape data obtained when calculating the above-described surface inclination angle distribution and the same analysis conditions, and the numerical values of the optical sheet Ra, Rz.
Next, a “Save Data” button was displayed in the Surface Map screen, and the analyzed three-dimensional curved surface roughness data was saved. Then, the saved data was read by Advanced Texture Application, and the following analysis conditions were applied.
(Analysis conditions)
・ High FFT Filter: off
・ Low FFT Filter: off
・ Remove: Plane
Next, the Peak / Valleys screen was displayed, and the number of peaks was counted from “Peaks Stats”. However, in order to remove non-significant peaks, the peaks whose area is 1/10000 or more of the total measurement area (414 × 414 μm ² ) and whose height is 1/10 or more of Rtm were counted. Rtm can be read from the “Roughness / Waviness Map” screen, and represents the average of the maximum height for each section when the entire measurement area is divided into 3 × 3. And Smp was computed based on the said Formula (4).

[Glitter]
In each of the optical sheets obtained in Examples and Comparative Examples, the surface of the optical sheet on which the antiglare layer is not formed and the glass surface on which the black matrix (glass thickness 0.7 mm) is not formed are transparently adhered. It stuck together with the agent. For the sample thus obtained, a white surface light source (manufactured by HAKUBA, LIGHTBOX, average luminance of 1000 cd / m ² ) was placed on the black matrix side, thereby generating pseudo glare. This was photographed from the optical sheet side with a CCD camera (KP-M1, C mount adapter, close-up ring; PK-11A Nikon, camera lens; 50 mm, F1.4s NIKOR). The distance between the CCD camera and the optical sheet was 250 mm, and the focus of the CCD camera was adjusted to match the optical sheet. Images taken with a CCD camera were taken into a personal computer and analyzed with image processing software (ImagePro Plus ver. 6.2; manufactured by Media Cybernetics) as follows.
First, an evaluation location of 200 × 160 pixels was selected from the captured image, and converted to a 16-bit gray scale at the evaluation location. Next, the low-pass filter was selected from the enhancement tab of the filter command, and the filter was applied under the conditions of “3 × 3, number of times 3, strength 10”. As a result, components derived from the black matrix pattern were removed. Next, flattening was selected, and shading correction was performed under the condition of “background: dark, object width 10”. Next, contrast enhancement was performed with “contrast: 96, brightness: 48” using a contrast enhancement command. The obtained image was converted to an 8-bit gray scale, and the variation in the value for each pixel was calculated as a standard deviation value for 150 × 110 pixels in the image, thereby glaring was digitized. It can be said that the smaller the numerical value of the glare value, the less the glare. Note that the evaluation was performed with the black matrix having a pixel density of 350 ppi or the pixel density of 200 ppi.

[Anti-glare]
An evaluation sample in which a black acrylic plate is bonded to a substrate side of the obtained optical sheet via a transparent adhesive is placed on a horizontal plane, and a fluorescent lamp is placed 1.5 m above the evaluation sample for evaluation. A visual sensory evaluation was performed from various angles in an environment in which a fluorescent lamp was transferred onto the sample and the illuminance on the sample for evaluation was 800 to 1200 Lx, and evaluation was performed according to the following criteria.
○: An image of a fluorescent lamp cannot be recognized from any angle.
Δ: An image of a fluorescent lamp is reflected, but the outline of the fluorescent lamp is blurred and the boundary portion of the outline cannot be recognized.
X: An image of a fluorescent lamp is reflected like a mirror surface, and the outline (boundary boundary) of the fluorescent lamp can be clearly recognized.
[Contrast (dark room)]
In contrast ratio measurement, when a cold cathode tube light source with a diffusion plate installed as a backlight unit was used, two polarizing plates (AMN-3244TP manufactured by Samsung) were used, and the polarizing plates were installed in parallel Nicols. By dividing L _max of the luminance of light passing through the light by L _min of the luminance of light passing through when installed in crossed Nicol, the antiglare film (light transmissive substrate + antiglare layer) is made the outermost surface. The contrast (L ₁ ) when placed and the contrast (L ₂ ) when only the light-transmitting substrate is placed on the outermost surface are calculated, and (L ₁ / L ₂ ) × 100 (%) is calculated. Thus, the contrast ratio was calculated.
The luminance was measured using a color luminance meter (BM-5A manufactured by Topcon Corporation) in a dark room environment with an illuminance of 5 Lx or less. The measurement angle of the color luminance meter was set to 1 °, and measurement was performed with a visual field of 5 mm from the vertical direction on the sample. The light quantity of the backlight was set such that the luminance when the two polarizing plates were set in parallel Nicol was 3600 cd / m ² without the sample being set.

[Haze]
First, haze (overall haze) was measured according to JIS K-7136: 2000 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). In addition, the concavo-convex shape is crushed and flattened by attaching a TAC film having a thickness of 80 μm (manufactured by FUJIFILM Corporation, TD80UL) to the surface of the optical sheet via a transparent adhesive, thereby eliminating the influence of haze caused by the surface shape. Then, the haze was measured to determine the internal haze (Hi). Then, the surface haze (Hs) was obtained by subtracting the internal haze value from the overall haze value. The light incident surface was the substrate side.
[Total light transmittance]
The total light transmittance of the optical sheet was measured according to JIS K7361-1: 1997 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). The light incident surface was the substrate side.
[Transparent image clarity]
4 types through optical combs having widths of 2 mm, 1 mm, 0.5 mm and 0.125 mm in accordance with JIS K7105: 1981 using image clarity measuring device (trade name: ICM-1T) manufactured by Suga Test Instruments Co., Ltd. The transmitted image definition was measured and the sum of these was calculated.

[Whitening]
A sample in which the surface of the optical sheet on the transparent substrate side and a black acrylic plate were bonded together via a transparent adhesive was prepared. About the produced sample, the cloudiness feeling was observed on the following references | standards in the dark room under the desk stand which uses a 3 wavelength fluorescent lamp tube as a light source.
A: Whiteness was not observed.
C: Whiteness was observed.
[Visibility of scratches]
The concavo-convex surface of the sample optical sheet prepared by the whitening evaluation was rubbed once with # 0000 steel wool at a load of about 100 g / cm ² , and the scratches on the surface were visually evaluated. As a result, “O” indicates that the scratches are not noticeable, and “X” indicates that the scratches are conspicuous.
[Interference fringes]
The two optical sheets were overlapped so that the uneven surface side of one optical sheet and the transparent substrate side of the other optical sheet face each other. As a result, “O” indicates that no interference fringes occurred, and “X” indicates that interference fringes occurred.

2. Production of optical sheet [Example 1]
On a transparent substrate (80 μm thick triacetylcellulose resin film (TAC), manufactured by Fuji Film, TD80UL), the antiglare layer coating solution 1 having the following formulation was applied and dried at 70 ° C. and a wind speed of 5 m / s for 30 seconds. Then, ultraviolet rays were irradiated under a nitrogen atmosphere (oxygen concentration of 200 ppm or less) so that the integrated light amount was 100 mJ / cm ² to form an antiglare layer, thereby obtaining an optical sheet. The film thickness of the antiglare layer was 7.5 μm.

<Anti-glare coating solution 1>
Pentaerythritol triacrylate 10 parts (Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 45 parts of urethane acrylate (Nippon Gosei Co., Ltd., UV1700B) ・ 3 parts of photopolymerization initiator (Irgacure 184, manufactured by BASF)
・ 0.2 parts of silicone leveling agent (Momentive Performance Materials, TSF4460)
・ Translucent particles 12 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Average particle size 6 μm, refractive index 1.535)
・ Inorganic ultrafine particles 160 parts (manufactured by Nissan Chemical Co., Ltd., silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (MIBK) 110 parts

[Example 2]
An optical sheet was obtained in the same manner as in Example 1 except that 10 parts of the translucent particles of Example 1 and 170 parts of the inorganic ultrafine particles were changed.

[Example 3]
An optical sheet was obtained in the same manner as in Example 1 except that the light-transmitting particles in Example 1 were changed to 15 parts and the inorganic ultrafine particles were changed to 150 parts.

[Comparative Example 1]
In the same manner as in Example 1, except that the antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 2 of the following formulation and the film thickness of the antiglare layer (uneven layer) was 2 μm. A sheet was obtained.
<Anti-glare coating solution 2>
・ 100 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 14 parts of inorganic fine particles (manufactured by Fuji Silysia Chemical Ltd., gel method amorphous silica)
(Hydrophobic treatment, average particle size (laser diffraction scattering method) 4.1 μm)
-Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ 0.2 parts of silicone leveling agent (TSF4460 manufactured by Momentive Performance Materials)
・ Solvent 1 (toluene) 150 parts ・ Solvent 2 (MIBK) 35 parts

[Comparative Example 2]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 3 having the following formulation, and the film thickness of the antiglare layer (uneven layer) was 4.5 μm. An optical sheet was obtained.
<Anti-glare layer coating solution 3>
・ 90 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ Acrylic polymer (Mitsubishi Rayon Co., Ltd., molecular weight 75,000) 10 parts ・ Photopolymerization initiator 3 parts (BASF Co., Ltd., Irgacure 184)
・ Silicon-based leveling agent 0.1 part (TSF4460 manufactured by Momentive Performance Materials)
・ 12 parts of translucent particles (manufactured by Soken Chemical Co., Ltd., spherical polystyrene particles)
(Particle size 3.5μ, refractive index 1.59)
・ Solvent 1 (toluene) 145 parts ・ Solvent 2 (cyclohexanone) 60 parts

[Comparative Example 3]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 4 having the following formulation, and the film thickness of the antiglare layer (concave / convex layer) was 7.0 μm. An optical sheet was obtained.
<Anti-glare layer coating solution 4>
・ 38 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
Isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., Ltd., M-313) 22 parts Photopolymerization initiator 5 parts (manufactured by BASF, Irgacure 184)
・ Silicon-based leveling agent 0.1 part (Momentive Performance Materials, TSF4460)
・ Translucent particles 20 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Particle size 5μ, refractive index 1.525)
・ Inorganic ultrafine particles 120 parts (manufactured by Nissan Chemical Industries, silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (toluene) 135 parts

[Comparative Example 4]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 5 of the following formulation, and the film thickness of the antiglare layer (uneven layer) was 5.0 μm, as in Example 1. An optical sheet was obtained.
<Anti-glare layer coating solution 5>
・ 38 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
Isocyanuric acid EO-modified triacrylate (M-313 manufactured by Toa Gosei Co., Ltd.) 22 parts Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ Silicon-based leveling agent 0.1 part (TSF4460 manufactured by Momentive Performance Materials)
・ Translucent particles 12 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Particle size 3.5μ, refractive index 1.545)
・ Inorganic ultrafine particles 120 parts (manufactured by Nissan Chemical Industries, silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (toluene) 135 parts

  As is clear from the results in Table 1, the optical sheets of Examples 1 to 3 can impart various properties such as anti-glare properties, and can prevent glare in ultra-high-definition display elements having a pixel density of 300 ppi or more. It was also excellent in contrast. In addition, the optical sheets of Examples 1 to 3 have a much better effect than the optical sheets of Comparative Examples 1 to 4 in terms of antiglare properties of display elements having a pixel density of 350 ppi, but display with a pixel density of 200 ppi. About the glare prevention performance of an element, the difference of an effect with the optical sheet of Comparative Examples 1-4 is small. From this, it can be seen that the optical sheets of Examples 1 to 3 are extremely useful for an ultra-high-definition display element having a pixel density of 300 ppi or more. In addition, although the above-mentioned evaluation of anti-glare property was performed in an environment with an illuminance of 800 to 1200 Lx, the anti-glare sheets of Examples 1 to 3 have good anti-glare property even in an outdoor environment with an illuminance of 10,000 Lx or more. It was a thing.

3. Production of Touch Panel On the transparent substrate side of the optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4, an ITO conductive film having a thickness of 20 nm was formed by a sputtering method to obtain an upper electrode plate. Next, an ITO conductive film having a thickness of about 20 nm was formed by sputtering on one surface of a 1 mm thick tempered glass plate to obtain a lower electrode plate. Next, ionizing radiation curable resin (Dot Cure TR5903: Taiyo Ink Co., Ltd.) is printed on the surface of the lower electrode plate having the conductive film as a coating solution for spacers in the form of dots by the screen printing method. Irradiation was performed, and spacers having a diameter of 50 μm and a height of 8 μm were arranged at intervals of 1 mm.
Next, the upper electrode plate and the lower electrode plate are arranged so that the conductive films face each other, and the edges are bonded with a double-sided adhesive tape having a thickness of 30 μm and a width of 3 mm. Examples 1-3 and Comparative Examples 1-4 A resistive film type touch panel was prepared.
When the obtained resistive touch panel was placed on a commercially available ultra-high-definition liquid crystal display (pixel density 350 ppi) and the presence or absence of glare was visually evaluated, the touch panels of Examples 1 to 3 were suppressed from glare. Also, there was little transfer of outside light, and visibility was good. In addition, the touch panels of Examples 1 to 3 did not impair the resolution of ultra-high-definition images and had good contrast in a bright room environment. On the other hand, the touch panels of Comparative Examples 1 to 4 were conspicuous. Moreover, since the touch panel of Comparative Example 2 has a relatively high noise inside the optical sheet, the resolution of the ultra-high definition video is slightly impaired.

4). Production of Display Device The optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4 and a commercially available ultra-high-definition liquid crystal display device (pixel density 350 ppi) are bonded together via a transparent adhesive, and Examples 1 to 3 are bonded. And the display apparatus of Comparative Examples 1-4 was produced. In addition, when bonding, the uneven surface of the optical sheet was made to face the side opposite to the display element.
When the presence or absence of glare of the obtained display device was visually evaluated, the display devices of Examples 1 to 3 were suppressed in glare, had little external light, and had good visibility. In addition, the display devices of Examples 1 to 3 did not lose the resolution of the ultra-high-definition video and had good contrast in the bright room environment. On the other hand, the display devices of Comparative Examples 1 to 4 were conspicuous. Further, the display device of Comparative Example 2 has a relatively high noise inside the optical sheet, so that the resolution of the ultra-high definition image is slightly impaired.

1: resistive film type touch panel, 11: transparent substrate, 12: transparent conductive film, 13: spacer 2: capacitive touch panel, 21: transparent substrate, 22: transparent conductive film (X electrode), 23: transparent conductive film ( Y electrode), 24: Adhesive layer

Claims (16)

  A touch panel having an optical sheet as a constituent member, wherein the optical sheet has a concavo-convex shape on a surface thereof, and an inclination angle interval indicating a half value of a peak value of the concavo-convex shape inclination angle distribution curve is provided. A touch panel used on the front surface of a display element of 5 to 15 degrees and a pixel density of 300 ppi or more.   The touch panel according to claim 1, wherein a ratio of an inclination angle of 0 to 1.25 degrees in an inclination angle of the uneven shape is 20% or less in cumulative percentage.   The touch panel according to claim 1 or 2, wherein an inclination angle indicating a peak value of the inclination angle distribution curve is 2 to 8 degrees.   The touch panel according to any one of claims 1 to 3, wherein an inclination angle indicating an inflection point in a plus direction from an inclination angle indicating a peak value of the inclination angle distribution curve is 4 to 15 degrees.   The touch panel according to any one of claims 1 to 4, wherein a skewness of the inclination angle distribution of the uneven shape is 0 to 1.5.   The touch panel according to any one of claims 1 to 5, wherein the concavo-convex inclination angle distribution has a kurtosis of 1.5 to 6.   The touch panel according to any one of claims 1 to 6, wherein a ratio of an inclination angle of 15 degrees or more in the inclination angle of the uneven shape is 3% or less in cumulative percentage.   A display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, wherein the optical sheet has a concavo-convex shape on a surface thereof, and a peak value of 1 of the inclination angle distribution curve of the concavo-convex shape A display device having an inclination angle interval of 5 to 15 degrees indicating a value of / 2.   An optical sheet having a concavo-convex shape on a surface thereof, a display element having a pixel density of 300 ppi or more and having an inclination angle interval of 5 to 15 degrees indicating a half value of a peak value of the concavo-convex inclination angle distribution curve Optical sheet used on the front side of the paper.   10. The optical sheet according to claim 9, wherein a ratio of an inclination angle of 0 to 1.25 degrees in an inclination angle of the uneven shape is 20% or less in cumulative percentage.   The optical sheet according to claim 9 or 10, wherein an inclination angle indicating a peak value of the inclination angle distribution curve is 2 to 8 degrees.   The optical sheet according to any one of claims 9 to 11, wherein an inclination angle indicating an inflection point in a plus direction from an inclination angle indicating a peak value of the inclination angle distribution curve is 4 to 15 degrees.   The optical sheet according to any one of claims 9 to 12, wherein a degree of distortion of the uneven-angle distribution of inclination angles is 0 to 1.5.   The optical sheet according to any one of claims 9 to 13, wherein the kurtosis of the concavo-convex inclination angle distribution is 1.5 to 6.   A method of selecting an optical sheet having a concavo-convex shape on a surface, wherein the inclination angle of the concavo-convex shape of the optical sheet is measured, and an inclination angle indicating a value half the peak value of the inclination angle distribution curve obtained from the measurement result A method for selecting an optical sheet used on the front surface of a display element having a pixel density of 300 ppi or more, wherein an optical sheet having an interval of 5 to 15 degrees is selected as an optical sheet.   A method for producing an optical sheet having a concavo-convex shape on the surface, wherein the concavo-convex shape of the optical sheet is produced such that the inclination angle interval indicating the peak value of the inclination angle distribution curve is 5 to 15 degrees. A method for manufacturing an optical sheet used on the front surface of a display element having a pixel density of 300 ppi or more.