KR102225830B1 - Touch panel, display device, optical sheet, method for selecting optical sheet, and method for manufacturing optical sheet - Google Patents

Abstract

There is provided a touch panel capable of preventing glare of an ultra-high-precision display device having a pixel density of 300 ppi or higher, and preventing a decrease in resolution of the ultra-high-precision display device.
It is a touch panel having an optical sheet as a constituent member,
The optical sheet has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and
Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,
A touch panel used on the front surface of a display device with a pixel density of 300ppi or higher.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

Description

A touch panel, a display device and an optical sheet, a method of sorting an optical sheet, and a method of manufacturing an optical sheet {TOUCH PANEL, DISPLAY DEVICE, OPTICAL SHEET, METHOD FOR SELECTING OPTICAL SHEET, AND METHOD FOR MANUFACTURING OPTICAL SHEET}

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

In recent years, mobile type information terminal devices with interactive communication functions, which are represented by tablet PCs and smartphones, and equipped with a transparent touch panel for information display and information input, have begun to be widely distributed not only in Japan but also in the world. did.

As a transparent touch panel, there is a resistive film method that is excellent in cost, but it is possible to manipulate gestures such as multi-touch, and it is difficult to impair the image quality of ultra-high-precision display elements. Demand for type capacitive touch panels is increasing.

An anti-glare sheet having an uneven structure may be provided on the surface of the touch panel for the purpose of preventing projection of external light or the like.

Furthermore, in order to prevent adhesion and interference fringes between members constituting the touch panel, adhesion between the touch panel and display elements, and prevention of interference fringes, etc., as the outermost substrate, the inner substrate, and the rearmost substrate of the touch panel, irregularities There are cases where an optical sheet having a structure is used.

However, when an optical sheet having a concave-convex structure such as an anti-glare film is used, there is a problem in that a phenomenon in which a slight variation in luminance is observed (flashing) in the image light due to the concave-convex structure occurs, thereby deteriorating the display quality. In particular, in recent ultra-high precision display devices (pixel density of 300 ppi or more), the glare tends to become stronger, and the glare problem is becoming more serious.

As a technique for preventing glare due to surface irregularities, the techniques of Patent Documents 1 to 9 have been proposed.

Japanese Patent Laid-Open Publication No. Hei 11-305010 Japanese Patent Publication No. 2002-267818 Japanese Patent Publication No. 2009-288650 Japanese Patent Publication No. 2009-86410 Japanese Patent Publication No. 2009-128393 Japanese Patent Publication No. 2002-196117 International Publication No. 2007/111026 Japanese Patent Publication No. 2008-158536 Japanese Patent Application Publication No. 2011-253106

Patent Documents 1 and 2 improve glare by imparting an internal haze. However, an ultra-high-precision display device having a pixel density of 300 ppi or more tends to have a strong glare. Therefore, if the glare is to be suppressed by only the internal haze, the internal haze must be increased. In addition, when the internal haze is large, the resolution tends to deteriorate, but this tends to be greater in the ultra-high-precision display device. Therefore, in Patent Documents 1 and 2, glare and a decrease in resolution cannot be simultaneously prevented in an ultra-high-precision display device having a pixel density of 300 ppi or more.

Patent Documents 3 to 9 are intended to improve glare while imparting anti-glare properties by designing the surface shape of the optical sheet into a specific shape. However, even in the techniques of Patent Documents 3 to 9, it is not possible to prevent glare of the ultra-high-precision display device having a pixel density of 300 ppi or more.

The present invention was made under such a situation, and even in the case of having an uneven structure, a touch panel, a display device, and a touch panel capable of preventing glare of image light of an ultra-high-precision display device having a pixel density of 300 ppi or more, and also preventing a decrease in resolution. It aims to provide an optical sheet. Another object of the present invention is to provide a method for selecting and manufacturing an optical sheet capable of preventing a decrease in resolution while preventing glare of image light of an ultra-high precision display device having a pixel density of 300 ppi or higher.

In order to solve the above problems, the present inventors have conducted extensive research on an optical sheet for preventing glare. First of all, it is considered that the cause of the glare is that when the video light passes through the optical sheet having surface irregularities, distortion occurs in the transmitted light due to the irregularities. For this reason, conventionally, in order to prevent glare, as in Patent Documents 3 to 9, a design in which the inclination angle of the irregularities is decreased and the smooth surface is increased (design to reduce the degree of irregularities) has been performed.

However, as described above, even if the design to reduce the degree of irregularities was able to prevent glare of a display device having a low pixel density, glare of an ultra-high precision display device having a pixel density of 300 ppi or more could not be prevented. In addition, portable information terminals represented by recent smartphones require a high degree of anti-glare property because they operate the touch panel outdoors, but a design that prevents glare by increasing the ratio of the smooth surface is such an advanced room. It wasn't something that could really satisfy Hyunsung.

In addition, simply by providing the internal haze as described above, it is not possible to simultaneously prevent glare and deterioration in resolution of an ultra-high-precision display device having a pixel density of 300 ppi or more.

Accordingly, the present inventors have achieved the present invention by controlling the internal haze or the surface haze to a constant value and paying attention to the formula (I) representing the ratio of the surface irregularities.

That is, the present invention provides a touch panel, a display device and an optical sheet, a method of sorting an optical sheet, and a method of manufacturing an optical sheet of the following [1] to [11].

[1] a touch panel having an optical sheet as a constituent member,

The optical sheet has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and

Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,

A touch panel used on the front surface of a display device with a pixel density of 300ppi or higher.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

[2] The touch panel according to claim 1, wherein the diffusion angle indicating the luminance of 1/2 of the virtual intensity in the forward transmission direction is "α", and the absolute value of α is 1.4 to 3.0°.

[3] The touch panel according to claim 1 or 2, wherein the diffusion angle indicating the luminance of 1/3 of the virtual intensity in the forward transmission direction is referred to as "β", and the absolute value of β is 1.9 to 5.0°.

[4] The touch panel according to any one of claims 1 to 3, wherein a diffusion angle indicating a luminance of 1/10 of the virtual intensity in the forward transmission direction is referred to as "γ", and an absolute value of γ is 3.5 to 8.0°.

[5] a display device comprising an optical sheet on a front surface of a display element having a pixel density of 300 ppi or more,

The optical sheet has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and

Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. A display device that satisfies the relationship of the following formula (I) when the average value of the strength obtained by extrapolating the straight lines to be connected by the forward transmission angle is "virtual strength in the forward transmission direction".

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

[6] an optical sheet having an uneven shape on one side,

The optical sheet has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and

Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,

Optical sheet used for the front surface of display devices with a pixel density of 300 ppi or higher.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

[7] The optical sheet according to claim 6, wherein the diffusion angle indicating an intensity of 1/2 of the virtual intensity in the forward transmission direction is "α", and the absolute value of α is 1.4 to 3.0°.

[8] The optical sheet according to claim 6 or 7, wherein the diffusion angle indicating an intensity of 1/3 of the virtual intensity in the forward transmission direction is referred to as "β", and the absolute value of β is 1.9 to 5.0°.

[9] The optical sheet according to any one of claims 6 to 8, wherein the diffusion angle indicating an intensity of 1/10 of the imaginary intensity in the forward transmission direction is referred to as "γ", and the absolute value of γ is 3.5 to 8.0°.

[10] It is a method of sorting an optical sheet having an uneven shape on one side,

(a) satisfying the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%, and

(b) Irradiating visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and measuring the intensity of the transmitted light in a certain angular range from the surface having the uneven shape Thus, the strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction by the forward transmission angle, and the strength at -2° and -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the strength of the straight line connecting the strength of the normal transmission angle is referred to as the "virtual strength in the normal transmission direction", the optical sheet satisfying the following formula (I) is selected,

A method of sorting an optical sheet used for a front surface of a display device having a pixel density of 300 ppi or more.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

[11] It is a manufacturing method of an optical sheet having an uneven shape on one side,

(a) satisfying the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%, and

(b) Irradiating visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the concave-convex shape of the optical sheet, and measuring the intensity in a certain angular range from the surface having the concave-convex shape of the transmitted light Thus, the strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction by the forward transmission angle, and the strength at -2° and -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the strength of the straight line connecting the strength of the normal transmission angle is “imaginary strength in the normal transmission direction”, it is prepared to satisfy the following formula (I),

A method of manufacturing an optical sheet used for a front surface of a display device having a pixel density of 300 ppi or more.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

The touch panel, display device, and optical sheet of the present invention can prevent glare of an ultra-high-precision display device having a pixel density of 300 ppi or higher while imparting various properties such as anti-glare property, and also prevent a decrease in resolution of an ultra-high-precision display device. can do. In particular, when the uneven surface of the optical sheet is used toward the viewer side, reflection of external light can be suppressed even under a bright outdoor environment, and high anti-glare properties can be imparted.

In addition, the optical sheet sorting method of the present invention can ensure the performance of preventing deterioration of the resolution while preventing glare, even if the optical sheet is not incorporated in the display device, thereby enabling efficient quality control of the optical sheet. have. Further, the optical sheet manufacturing method of the present invention can efficiently manufacture an optical sheet capable of preventing glare of image light without lowering the resolution of an ultra-high-precision display element having a pixel density of 300 ppi or more.

1 is a cross-sectional view showing an embodiment of a resistive touch panel of the present invention.
2 is a cross-sectional view showing an embodiment of the capacitive touch panel of the present invention.
3 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Example 1. FIG.
4 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Example 2. FIG.
5 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Example 3. FIG.
6 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Comparative Example 1. FIG.
7 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Comparative Example 2. FIG.
8 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Comparative Example 3. FIG.
9 is a diagram showing the intensity distribution of transmitted light of the optical sheet of Comparative Example 4. FIG.
10 is a scanning transmission electron micrograph (STEM) showing a cross section of an optical sheet of Example 1. FIG.

Hereinafter, an embodiment of the present invention will be described.

[Touch Panel]

The touch panel of the present invention is a touch panel having an optical sheet as a constituent member, the optical sheet has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, In addition, visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured, The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the intensity obtained by extrapolating the straight line connecting the lines by the normal transmission angle is referred to as the "virtual intensity in the normal transmission direction", the relationship of the following equation (I) is satisfied, will be.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

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 substrate such as a glass substrate and a plastic film substrate, and the surface on the substrate may have an uneven shape for imparting various properties such as anti-glare property, anti-adhesion, and interference fringe. The touch panel of the present invention is a substrate having an uneven shape on such a surface, and is formed using an optical sheet described later.

Further, the optical sheet to be described later can impart good anti-glare properties even in a bright outdoor environment, while also preventing glare and lowering of resolution. Therefore, it is preferable to use the touch panel of the present invention so that the concave-convex surface of the optical sheet to be described later faces the operator side (the side opposite to the display element). In a portable information terminal represented by a recent smartphone, since the display element is ultra-high precision and the touch panel is operated outdoors, the touch panel of the present invention is made so that the concave-convex surface of the optical sheet to be described later faces the operator's side. It is extremely useful to organize.

The resistive touch panel has a structure in which the conductive films 12 of a pair of upper and lower transparent substrates 11 having a conductive film 12 are disposed to face each other through a spacer 13 as shown in FIG. 1. Is a basic configuration, and a circuit not shown is connected. In the case of a resistive touch panel, it is preferable to use an optical sheet to be described later as the upper transparent substrate and/or the lower transparent substrate. Further, the upper transparent substrate and the lower transparent substrate have a multilayer structure including two or more substrates, and an optical sheet to be described later may be used as one of the substrates.

As the optical sheet in the resistive touch panel, for example, if an optical sheet described later is used as the upper transparent substrate, and the uneven surface of the optical sheet is used to face the opposite side to the lower transparent substrate, it is highly suitable for a resistive touch panel. In addition to providing the anti-glare property of, it is possible to prevent glare of the ultra-high-precision display device, and further, it is possible to prevent a decrease in the resolution of the ultra-high-precision display device. Further, in the case of this method of use, it is possible to make it difficult to see the scratches generated on the surface of the touch panel, the conductive film, etc., and is suitable in that it can contribute to the improvement of the yield.

In addition, by using an optical sheet to be described later as the lower transparent substrate of the resistive touch panel, and having the uneven surface of the optical sheet toward the upper transparent substrate side, surface reflection of the lower electrode is suppressed, and Can prevent glare. In addition, in the case of this method of use, it is possible to prevent the upper and lower conductive films from adhering to each other during operation, and also to prevent generation of interference fringes due to the proximity of the upper and lower conductive films.

Further, as the upper transparent substrate and/or the lower transparent substrate, when an optical sheet to be described later is used so that the uneven surface faces the opposite side to the upper electrode, it is suitable 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 widely used. The projection-type capacitive touch panel has a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X electrode are disposed via an insulator, and a circuit is connected. More specifically, the basic configuration is a form in which X electrodes and Y electrodes are formed on each surface of one transparent substrate, an X electrode, an insulator layer, and a Y electrode are formed in this order on a transparent substrate, As shown in Fig. 2, the X electrode 22 is formed on the transparent substrate 21, the Y electrode 23 is formed on the other transparent substrate 21, and laminated through an adhesive layer 24 or the like. The form to do, etc. are mentioned. In addition, there is a form in which other transparent substrates are further laminated on these basic forms.

In the case of a capacitive touch panel, it is preferable to use an optical sheet described later for at least one or more of the transparent substrates. Further, the transparent substrate has a multilayer structure including two or more substrates, and an optical sheet described later may be used as one of the substrates.

When the capacitive touch panel is configured to further include another transparent substrate on the above-described basic form, an optical sheet described later is used as the other transparent substrate, and the uneven surface of the optical sheet is the opposite side to the basic form side. When the concave-convex surface faces toward the operator, it is possible to impart high anti-glare properties to the capacitive touch panel, and to prevent glare of the ultra-high-precision display element, and further, ultra-high-precision display. It is possible to prevent the deterioration of the resolution of the device. Further, this method of use is suitable in that it is possible to make it difficult to show the shape of the electrode pattern and scratches generated on the surface of the touch panel, the conductive film, and the like.

In addition, when the capacitive touch panel is a configuration in which an X electrode is formed on a transparent substrate, a Y electrode is formed on another transparent substrate, and laminated through an adhesive or the like, an optical sheet to be described later is provided as at least one transparent substrate. The same effect as described above can be obtained even when the containing one is used, and the uneven surface of the optical sheet faces the side opposite to the basic form side, and the uneven surface faces the operator's side.

Further, as a transparent substrate for a capacitive touch panel, when an optical sheet to be described later is used so that the uneven surface faces the opposite side to the operator, it is suitable in that adhesion and interference fringes can be prevented.

(Optical sheet)

The optical sheet used for the touch panel of the present invention has a concave-convex shape on one side, an internal haze of 5 to 30% or a surface haze of 22 to 40%, and the optical sheet has a concave-convex shape. Visible light is irradiated perpendicularly to the optical sheet from the opposite plane direction, and the intensity of the transmitted light in a certain angular range from the side having an uneven shape was measured, and the intensity at +2° with respect to the forward transmission direction and The strength obtained by extrapolating the straight line connecting the strength at +1° by the forward transmission angle and the straight line connecting the strength at -2° and the strength at -1° with respect to the forward transmission direction by the forward transmission angle When the average value of is "virtual intensity in the forward transmission direction", the relationship of the following formula (I) is satisfied.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

Hereinafter, an optical sheet having an internal haze of 5 to 30% and satisfying the relationship of the formula (I) is referred to as "optical sheet A", and an optical sheet having a surface haze of 22 to 40% and satisfying the relationship of the formula (I). It may be referred to as "optical sheet B". In addition, the above division does not exclude from the present invention an optical sheet having an internal haze of 5 to 30% and a surface haze of 22 to 40%.

The optical sheet used for the touch panel of the present invention has an internal haze or a surface haze in a certain range, and a ratio of [intensity in the forward transmission direction / virtual intensity in the forward transmission direction] (hereinafter, referred to as ``intensity ratio'') Is in a certain range, it is possible to prevent glare of image light of an ultra-high-precision display device having a pixel density of 300 ppi or more, and also to prevent a decrease in resolution. Even if only one of the internal haze or the surface haze and the intensity ratio satisfies the scope of the present invention, the prevention of glare and the reduction of resolution are not compatible. Hereinafter, the reason will be described.

Reasons common to optical sheet A and optical sheet B

First of all, it is considered that the cause of the glare is that when the video light passes through the optical sheet having surface irregularities, distortion occurs in the transmitted light due to the irregularities. For this reason, conventionally, in order to prevent glare, a design that reduces the degree of unevenness by lowering the inclination angle as in Patent Documents 3 to 9, or a design that imparts an internal haze as in Patent Documents 1 and 2 to reduce the glare. It was being done.

However, only by designing to reduce the degree of irregularities or by providing internal haze, it was not possible to prevent the glare of the image light of an ultra-high-precision display device having a pixel density of 300 ppi or more.

As a result of intensive research, the present inventors showed that when the degree of irregularities was weakened by lowering the inclination angle as in the prior art, the ratio of the roughly smooth portions rather than the irregularities increased, and the boundary between the roughly smooth portion and the irregular surface (replaceable In other words, it was found that the place where the sharp angle change occurs) is one factor of the flashing. In addition, although the JIS standard (JIS B0601) regarding the surface shape prescribes the use of a contact type surface shape measuring device, in the relationship between the shape of the stylus and the shape of the surface, the measurement result may not accurately reflect the shape of the surface.

Reasons for optical sheet A

The inventors of the present invention not only reduce the sense of glare by giving a constant internal haze such that the resolution is not lowered, but also the ratio of [intensity in the forward transmission direction/virtual intensity in the forward transmission direction] indirectly indicating the uneven shape (intensity ratio ), and by setting the intensity ratio to a certain range, it is possible to prevent the deterioration of the resolution while preventing glare of the ultra-high-precision display element.

The intensity ratio, which will be described later in detail, is approximated to the ratio of light impinging on the diffusion element (the sum of the internal diffusion element and the surface diffusion element). That is, if the intensity ratio is close to 1, it can be said that the rate at which the light passing through the optical sheet collides with the diffusion element is high, and as the intensity ratio becomes further from 1, the rate at which the light passing through the optical sheet collides with the diffusion element is increased. It can be said that there is little (in other words, "the ratio of the light passing right through it is large"). Also, the influence on the intensity ratio is much greater on the surface diffusion element than on the internal diffusion element. Therefore, the degree of irregularities (surface diffusion element) can be indirectly indicated by specifying the intensity ratio, and the degree of irregularities (surface diffusion element) can be more accurately indicated by specifying the internal haze.

In the optical sheet A used in the touch panel of the present invention, the intensity ratio is set to a value close to 1 while suppressing the internal haze to a certain range. For this reason, the optical sheet A shows that there are many surface diffusion elements among the diffusion elements, in other words, the irregularities have few surfaces close to smoothness, and the substantially entire surface has an irregular shape. That is, the optical sheet A is completely different from the design of the optical sheets of Patent Documents 3 to 9 having many substantially smooth locations.

The optical sheet A used in the touch panel of the present invention has the above-described surface shape (roughly the entire surface is concave-convex shape) defined indirectly by the intensity ratio, and has a predetermined internal haze. Since the optical sheet A has few substantially smooth surfaces and the entire surface has an uneven shape, it is considered that the boundary between the uneven portions and the substantially smooth portions on the surface of the optical sheet is reduced, so that glare can be easily prevented. In addition, the optical sheet A is considered to be able to diversify the diffusion shape by further diffusing the light diffused by the internal haze by the surface shape, thereby preventing glare (to be exact, even in the present invention, some glare. However, in the present invention, by reducing the boundary between the uneven portion and the substantially smooth portion on the surface of the optical sheet A, or by diversifying the diffusion shape, the glare is averaged to make it less noticeable. I think).

In addition, since the optical sheet A has few substantially smooth surfaces on the uneven surface, reflection in the regular reflection direction can be suppressed, and high anti-glare properties capable of withstanding outdoor bright environments can be imparted.

Reasons for optical sheet B

The present inventors pay attention to the ratio (intensity ratio) of [intensity in forward transmission direction/virtual intensity in forward transmission direction] indirectly indicating the uneven shape, and indirectly define the uneven shape by setting the intensity ratio to a certain range. In addition, by setting the surface haze to a certain range and further specifying the uneven shape, it was possible to prevent the deterioration of the resolution while preventing the glare of the ultra-high-precision display element.

The intensity ratio, which will be described later in detail, is approximated to the ratio of light impinging on the diffusion element (the sum of the internal diffusion element and the surface diffusion element). That is, if the intensity ratio is close to 1, it can be said that the rate at which the light passing through the optical sheet collides with the diffusion element is high, and as the intensity ratio becomes further from 1, the rate at which the light passing through the optical sheet collides with the diffusion element is increased. It can be said that there is little (in other words, "the ratio of the light passing right through it is large"). Also, the influence on the intensity ratio is much greater on the surface diffusion element than on the internal diffusion element. Therefore, by defining the intensity ratio, the degree of irregularities (surface diffusion factor) can be indirectly expressed.

The optical sheet B used in the touch panel of the present invention has an intensity ratio close to one. For this reason, the optical sheet B shows that there are many surface diffusion elements among the diffusion elements, in other words, the irregularities have few surfaces close to smoothness, and the substantially entire surface has an irregular shape. That is, the optical sheet B is completely different from the design of the optical sheets of Patent Documents 3 to 9 in which there are many substantially smooth locations.

On the other hand, according to JIS K7136:2000 and ISO 14782:1999, haze is defined as "the percentage of transmitted light that deviates from incident light by 0.044 m (2.5°) or more by forward scattering among transmitted light passing through the test piece". That is, haze represents the ratio of scattered light in which incident light rays are scattered by ±2.5° or more. Further, as a physical property of light, it is known that the angle of light passing through the uneven surface is approximately 1/2 times the inclination angle. In other words, light passing through a location having an inclination angle exceeding 5° is reflected in the haze, but light passing through a location having an inclination angle less than 5° is not reflected in the haze.

The optical sheet B used in the touch panel of the present invention has an intensity ratio close to 1, has an almost uneven shape on the entire surface, and has an extremely low surface haze. This means that the optical sheet B used in the touch panel of the present invention contains a large number of irregularities with a small inclination angle (corrugations with an inclination angle of less than 5°) that are not reflected in the surface haze. In addition, since the optical sheet B used in the touch panel of the present invention has not small surface haze, it means that many irregularities (inclined angles of 5° or more) having a large inclination angle reflected in the surface haze are included.

The optical sheet B used in the touch panel of the present invention has an intensity ratio close to 1, and the entire surface is uneven because of a small number of roughly smooth surfaces, so that the boundary between the irregularities and roughly smooth regions on the surface of the optical sheet is small, so that it is glazed. I think it can be done easily to prevent it. In addition, since the optical sheet B has an intensity ratio close to 1, and has a surface haze in a range that is not too large and not too small, among the irregularities, the inclination angle is small (inclination angle less than 5°) and the inclination angle. Large irregularities (inclined angles of 5° or more) are mixed. As described above, the presence of various inclination angles among irregularities makes it easier to prevent glare (to be precise, it is thought that some glare occurs in the present invention. However, in the present invention, the surface of the optical sheet B is roughly smoothed with irregularities). It is thought that by reducing the boundary of one point or by making various inclination angles exist, the glare is averaged to make it less pronounced).

In addition, since the optical sheet B has few smooth surfaces on the uneven surface and has various inclination angles, it is possible to impart a high degree of anti-glare property that can withstand a bright outdoor environment. In addition, since the optical sheet B has roughly the entire surface uneven, and there are many irregularities with a small inclination angle that are not reflected in the haze, while preventing a decrease in resolution, when the optical sheet B is used as an anti-glare sheet Contrast can be prevented from deteriorating.

As described above, in the present invention, by using an optical sheet having an internal haze of 5 to 30% or a surface haze of 22 to 40%, and an intensity ratio of 1.0 or more and 4.0 or less, while providing various properties such as anti-glare properties, ultra-high precision display It is possible to prevent the device from flashing and deteriorating the resolution.

When the internal haze is less than 5% and the surface haze is less than 22%, or when the intensity ratio exceeds 4.0, glare cannot be prevented. In addition, when the internal haze exceeds 30% and the surface haze exceeds 40%, the resolution decreases. In addition, when the intensity ratio exceeds 4.0, the ratio of the places with the diffusion element decreases, making it difficult to impart a high degree of anti-glare property that can withstand outdoor bright environments, and a sharp angle change on the surface of the optical sheet. The number of places to be generated increases, and glare tends to occur.

The internal haze is preferably 5 to 25%, more preferably 10 to 18%. The surface haze is preferably 25 to 40%, more preferably 25 to 35%. The internal haze and the internal haze can be obtained by the method described in the examples.

The strength ratio is preferably 1.0 or more and 3.5 or less, more preferably 1.0 or more and 2.0 or less, and still more preferably 1.0 or more and 1.5 or less.

(Calculation method of ratio of [intensity in forward transmission direction/virtual intensity in forward transmission direction])

First, the strength of the optical sheet is measured as follows.

Visible light (parallel light rays) is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet. It is preferable that the surface on the opposite side to the surface having the uneven shape is substantially smooth. When the surface opposite to the surface having the uneven shape is not substantially smooth, a substrate having an approximately smooth surface is bonded through an adhesive layer tape, and visible light is incident perpendicularly to the optical sheet from the approximately smoothed surface direction, Measure the strength. Moreover, the substantially smooth surface means that Ra is 0.02 micrometer or less. Then, with respect to the transmitted light, the light receiver is scanned every 1° in a certain angle range from the side of the surface having the uneven shape, and the intensity (luminosity) at each angle is measured. As for the measurement range, the vertical direction is set to 0° (forward transmission direction), and measurement in the range of about ±20° may be performed. When measuring the intensity, the brightness of the light source is made constant. In addition, when measuring the intensity (luminosity), the aperture angle of the light receiver detected by the aperture of the light receiver is set to 1°. For this reason, for example, in the measurement of 0° (forward transmission direction), the range of ±0.5° is measured, in the measurement of 1°, the range of 0.5 to 1.5° is measured, and in the measurement of -1°, -0.5 to- It measures a range of 1.5°. The device for measuring the intensity is not particularly limited, and a general-purpose variable angle photometer (goniophotometer) can be used. In the present invention, as a variable-angle photometer, the brand name GC5000L manufactured by Nippon Denshoku Kogyo Co., Ltd. (beam diameter: about 3 mm, inclination angle within the beam: within 0.8°, aperture angle of the receiver: 1°) was used.

3 to 9 are diagrams showing intensity distributions of transmitted light of the optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4;

As described above, after measuring the strength every 1° in a certain range, as shown in FIG. 3, a straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction is a forward transmission angle. The extrapolated strength and the strength obtained by extrapolating the straight line connecting the strength at -2° and the strength at -1° with respect to the forward transmission direction by the forward transmission angle were calculated, and the average value of the calculated two intensities was calculated as “normal transmission. The virtual strength of the direction”. According to the "virtual strength in the forward transmission direction" calculated as described above and the strength in the forward transmission direction (intensity in the original forward transmission direction), the ratio of the [intensity in the forward transmission direction / the virtual strength in the forward transmission direction] (intensity ratio ) Can be calculated.

In addition, the intensity distribution diagrams in Figs. 3 to 9 are approximate curves by linear interpolation of the intensity values per 1°, but the extrapolation of the straight line to the forward transmission angle when calculating the intensity ratio is performed based on the measured values.

Next, the meaning of the intensity ratio will be described.

In the optical sheet, there are a location with a diffusion element (a location where the surface is uneven, a location with a diffusion particle inside), and a location without a diffusion element (a location where the surface is substantially smooth and has no diffusion particles inside). have. For this reason, the diffusely transmitted light is a combination of light "directly passing" without colliding with the diffuser element and light colliding with the diffuser element. In other words, the intensity distribution measured as described above is a synthesis of light that "passes directly" and light that collides with the diffusion element. Therefore, the intensity in the original forward transmission direction shown in Figs. 3 to 9 is also the intensity obtained by combining the light "directly passing" and the light colliding with the diffusion element.

On the other hand, since the glare is considered to be caused by distortion in transmitted light by the surface diffusion element among the diffusion elements, first of all, it is necessary to know the diffusion characteristics of the light impinging on the diffusion element among the synthesized forward-transmission direction intensity. And the virtual intensity in the forward transmission direction can be approximated as the normal transmission of light colliding with the diffusion element.

Therefore, the ratio of [intensity in forward transmission direction/virtual intensity in forward transmission direction] approximates the ratio of light impinging on the diffusion element. That is, if the intensity ratio is close to 1, it can be said that the rate at which light passing through the optical sheet collides with the diffusion element is high, and as the intensity ratio becomes greater than 1, the rate at which the light transmitted through the optical sheet collides with the diffusion element is increased. It can be said that there is little (in other words, "the ratio of the light passing right through it is large").

As described above, by defining the internal haze in a certain range and defining the intensity ratio, the degree of irregularities (surface diffusion factor) is indirectly displayed. In addition, by defining the intensity ratio and defining the surface haze as described above, the degree of unevenness (surface diffusion factor) can be further specified.

In addition, since the intensity of transmission and the intensity of reflection exhibit approximately the same behavior, it can be said that the high rate of collision of light passing through the optical sheet on the diffusion element is high in the proportion of the external light impinging on the diffusion element. That is, the evaluation of the above-described strength ratio also leads to the evaluation of anti-glare properties.

(α, β and γ)

All of α, β, and γ are parameters based on the "virtual intensity" in the forward transmission direction. That is, α, β, and γ are parameters representing the magnitude of diffusion only in the presence of the diffusion element (the intensity in the original forward transmission direction includes light transmitted through a substantially smooth area). α is a diffusion angle representing 1/2 of the imaginary intensity in the forward transmission direction, β is a diffusion angle representing 1/3 of the imaginary intensity in the forward transmission direction, and γ is a diffusion angle representing 1/10 of the imaginary intensity in the forward transmission direction to be. α, β, and γ can be calculated based on the intensity distribution diagram created by an approximate curve by linear interpolation of the intensity values for each 1° and the imaginary intensity in the forward transmission direction calculated as described above.

When the display device is visually evaluated, α means an angle at which the difference between the virtual intensity in the forward transmission direction is not recognized. Also, the diffusion elements (internal diffusion elements and surface diffusion elements) capable of determining α have a weak degree of diffusion. Therefore, a large α means that there are many diffusion elements with a weak degree of diffusion, and in the surface diffusion element, it means that there are many irregularities with a small inclination angle.

In the optical sheet used for the touch panel of the present invention, the absolute value of α is preferably 1.4 to 3.0°, more preferably 1.5 to 3.0°, and still more preferably 1.7 to 2.5°. By setting the absolute value of α in the above range, irregularities having a small inclination angle exist in a balanced manner, and various inclination angles exist among the irregularities, so that glare can be more easily prevented. Further, by making the absolute value of α in the above range, it is possible to impart anti-glare properties and to prevent a decrease in resolution due to excessive diffusion. In addition, the absolute value of α, the absolute value of β, and the absolute value of γ described later are taken as average values in the positive direction and the negative direction.

When the display device is visually evaluated, β denotes a diffusion angle within a range in which the difference between the forward transmission direction and the virtual intensity can be recognized. Also, the diffusion elements (internal diffusion elements and surface diffusion elements) that can determine β have a moderate degree of diffusion. Therefore, a large β means that there are many diffusion elements having a moderate degree of diffusion, and in the surface diffusion elements, it means that there are many irregularities having a medium inclination angle.

In the optical sheet used for the touch panel of the present invention, the absolute value of β is preferably 1.9 to 5.0°, more preferably 2.0 to 4.5°, and still more preferably 2.3 to 4.0°. By setting the absolute value of β in the above range, irregularities having a moderate inclination angle exist in a balanced manner, and various inclination angles exist in the irregularities, so that glare can be more easily prevented. Further, by setting the absolute value of β in the above range, it is possible to impart anti-glare properties and to prevent a decrease in resolution due to excessive diffusion.

γ is an index indicating the downstream of diffusion, that is, to what extent extremely strong diffusion exists among the diffusion elements. Therefore, when γ is large, it means that there are many diffusion elements with a large degree of diffusion. γ means that although the influence of the internal diffusion element is large, in the surface diffusion element, there are many irregularities having a large inclination angle.

The optical sheet used for the touch panel of the present invention preferably has an absolute value of γ of 3.5 to 8.0°, more preferably 4.0 to 7.5°, and even more preferably 4.5 to 6.5°. When the absolute value of γ is set to 3.5° or more, various inclination angles exist in the irregularities due to the presence of irregularities having a large inclination angle, so that glare can be more easily prevented. Further, by setting the absolute value of γ to be 8.0° or less, it is possible to prevent the optical sheet from whitening due to excessively large irregularities with a large inclination angle, and a decrease in contrast can be prevented when the optical sheet is used as an anti-glare sheet. .

In addition, from the viewpoint of making the effects of α, β and γ easier to obtain, it is preferable that the absolute values of α, β and γ satisfy one or more of the conditions of the following formulas (II) to (IV), and the above conditions It is more preferable to satisfy two or more of the above, and even more preferably to satisfy all of the above conditions.

2.0°≤|γ|-|α|≤5.0° (Ⅱ)

1.5°≤|γ|-|β|≤4.0° (Ⅲ)

0.5°≤|β|-|α|≤2.0° (IV)

It is more preferable that |γ|-|α| is 2.5° or more and 4.0° or less. Further, it is more preferable that |γ|-|β| is 2.0° or more and 3.5° or less. In addition, it is more preferable that |β|-|α| is 0.6° or more and 1.5° or less.

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

The optical sheet preferably has a haze (JIS K7136:2000) of 25 to 60%, more preferably 30 to 60%, and even more preferably 30 to 50%. By setting the haze to 25% or more, it is possible to impart anti-glare properties and make it difficult to show the shape and flaws of the electrode. Further, when the haze is set to 60% or less, it is possible to prevent a decrease in the resolution of the ultra-high-precision display element and easily prevent a decrease in contrast.

Further, the ratio (Hs/Hi) of the surface haze (Hs) to the internal haze (Hi) is preferably 1.0 to 5.0, more preferably 2.0 to 5.0, and still more preferably 2.5 to 4.5.

The optical sheet is an optical sheet having a width of 2 mm, 1 mm, 0.5 mm, and 0.125 mm using an image sharpness measuring device specified in JIS K7105:1981 from the viewpoint of making it difficult to see the shape or scratch of the electrode. It is preferable that the sum of the four types of transmission image sharpness passed through a comb is 100% or less, and it is more preferable that it is more than 20% and 80% or less.

The arithmetic mean roughness Ra of the uneven shape of the optical sheet is preferably 0.20 to 0.70 µm, more preferably 0.25 to 0.50 µm. By setting Ra to 0.20 μm or more, glare can be easily prevented, and anti-glare 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. have. Further, by setting Ra to 0.70 µm or less, it is possible to easily prevent a decrease in resolution and contrast. In addition, Ra and Rz and Smp mentioned later are values which were made into a cut-off value of 0.8 mm.

In addition, in the present invention, Ra is a three-dimensional expansion of Ra, a two-dimensional roughness parameter described in JIS B0601: 1994, with orthogonal coordinate axes X and Y axes on the reference plane, and the roughness curve is Z (x, y), and the reference plane When the size of is Lx and Ly, it is calculated by the following formula (1).

A=Lx×Ly

In addition, if the above-described Z _{i and j} are used, it is calculated by the following formula (2).

N: Total number of points

The ten-point average roughness Rz of the uneven shape of the optical sheet is preferably 1.00 to 3.50 µm, more preferably 1.20 to 3.00 µm. By setting Rz to 1.00 μm or more, glare can be easily prevented, anti-glare 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. have. Further, by setting Rz to 3.50 µm or less, since there is no convex portion having an extremely high elevation, it is possible to easily prevent a decrease in resolution and contrast.

In addition, from the viewpoint of making the above-described effects of Ra and Rz easier to obtain, the ratio of Rz and Ra [Rz/Ra] is preferably 6.0 or less, more preferably 4.0 to 6.0, and even more preferably 4.5 to 5.7. .

In the present invention, Rz is a three-dimensional extension of Rz, which is a two-dimensional roughness parameter described in JIS B0601: 1994. On the reference plane, a number of straight lines passing through the center of the reference plane are placed radially at 360° to cover the entire area, and a cross-sectional curve cut based on each straight line is obtained from a three-dimensional roughness curved surface, and the average of 10 points in the cross-sectional curve The roughness (the average of the heights of the heights from the highest to the 5th in order from highest to the highest and the sum of the average depths from the deepest to the 5th in order from deepest to deepest) is calculated. It is calculated by averaging the top 50% of the many 10-point average illuminances thus obtained.

The average spacing Smp of the irregularities of the uneven shape of the optical sheet is preferably 25 to 100 µm, more preferably 30 to 80 µm, and still more preferably 30 to 70 µm. By setting Smp in the above range, it is possible to have an uneven shape that is not too gentle and not too steep, and it is possible to easily prevent glare, as well as anti-glare property, adhesion prevention, interference fringe prevention, electrode shape and scratches are not possible. It can easily exhibit various performances such as visualization, prevention of deterioration of resolution, and prevention of whitening.

Smp is calculated as follows. Assuming that the number of floors when the area surrounded by one area at a portion higher than the reference surface from the 3D roughness surface is one floor is Ps, and the area of the entire measurement area (reference surface) is A, then Smp is the following equation ( It is calculated from 3).

The Ra, Rz, and Smp can be calculated by the measurement and analysis application software "Metro Pro" attached to the "New View" series of interference microscopes described above.

The three-dimensional average inclination angle (θa _3D ) of the uneven shape of the optical sheet is preferably 3.0 to 9.0°, more preferably 4.0 to 8.0°, and still more preferably 4.5 to 7.0°. By setting θa _3D to 3.0° or more, it is possible to easily impart various properties such as anti-glare properties. Further, by setting θa _3D to 9.0° or less, whitening, reduction in resolution, and reduction in contrast can be easily prevented. The three-dimensional average inclination angle θa _3D can be calculated by the method described in the Examples.

The above-described optical sheet has an uneven shape on one side and can be used without particular limitation as long as it has light transmittance.

Further, the optical sheet may be a single layer of an uneven layer, or a multilayer having an uneven layer on a transparent substrate. In terms of handling property and ease of manufacture, a configuration having an uneven layer on a transparent substrate is suitable.

Further, the optical sheet may have a functional layer such as an antireflection layer, an antifouling layer, and an antistatic layer on the uneven shape and/or on the surface opposite to the uneven shape. Further, in the case of a configuration having an uneven layer on the transparent substrate, a functional layer may be provided between the transparent substrate and the uneven layer in addition to the above locations.

It is preferable that the surface of the optical sheet on the side opposite to the uneven shape is substantially smooth. For example, when the optical sheet is a single layer of an uneven layer, it is preferable that the surface on the opposite side to the uneven surface is substantially smooth. In addition, when the optical sheet has a concave-convex layer on the transparent substrate, it is preferable that the surface of the transparent substrate on the opposite side to the surface having the concave-convex layer is substantially smooth. Further, when the optical sheet has a functional layer on the surface opposite to the uneven shape, it is preferable that the surface of the functional layer is substantially smooth. Here, "roughly smoothing" means that Ra is 0.02 µm or less.

In addition, when Ra of the surface on the opposite side to the side having the uneven shape of the optical sheet exceeds 0.02 µm, the opposite side surface is roughly smoothed to measure the intensity ratio and internal haze. In order to substantially smooth the surface on the opposite side, the measurement method of the internal haze of the examples, and a transparent plastic film having a substantially smooth surface may be bonded to the opposite surface through an adhesive layer tape.

In order to make the internal haze of the optical sheet 5 to 30%, the internal diffusion element may be adjusted. Specifically, the concave-convex layer is formed of a binder resin and light-transmitting particles, and the internal diffusion element can be adjusted by controlling the refractive index of the binder resin, the shape of the light-transmitting particles, the dispersion state, the particle diameter, the amount of addition, and the refractive index. In addition, the concentration of additives other than the translucent particles that can be added to the binder resin also affects the internal diffusion factor.

In order to make the surface haze of the optical sheet 22 to 40%, the surface diffusion element may be adjusted. Specifically, the uneven layer is formed of a binder resin and light-transmitting particles, and the surface diffusion element can be adjusted by controlling the shape of the light-transmitting particles, the dispersion state of the particles, the particle diameter, the amount of particles added, and the thickness of the uneven layer. In addition, it is preferable to consider the inclination angle of the unevenness as the surface diffusion element, and the inclination angle of the unevenness can be adjusted by a method described later.

In addition, in order to make the intensity ratio of the optical sheet 1.0 or more and 4.0 or less, it is preferable to increase the ratio of the diffusion elements of the uneven layer and reduce the ratio of the light passing right through. For this purpose, it is preferable to eliminate substantially smooth locations in the uneven layer as much as possible, and make it a shape in which substantially the whole of the uneven layer becomes an inclined surface.

In addition, in order to make α, β, and γ (especially β and γ) of the optical sheet within the above-described range, the uneven surface of the optical sheet is not simply made a gentle inclination, but various inclination angles including inclinations having a large inclination It is preferable to mix.

As a method for forming the irregularities, for example, 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 may be mentioned. Among these methods, from the viewpoint of reproducibility of the concave-convex shape, molding by the mold of 3) is suitable, and from the viewpoint of productivity and multi-product correspondence, the coating film formed by coating of 4) is suitable.

Molding by a mold can be produced by preparing a mold having a shape complementary to the uneven surface, pouring a material constituting the uneven layer such as a polymer resin or glass into the mold and curing it, and then taking it out from the mold. In the case of using a transparent substrate, it can be produced by pouring a polymer resin or the like into a mold, superimposing a transparent substrate thereon, curing the polymer resin, etc., and taking out each transparent substrate from the mold. In the case of imparting internal diffusion with light-transmitting particles or additives, when pouring a polymer resin or the like into the mold, the light-transmitting particles or additives may be further poured.

In the formation of a coating film by coating, an uneven layer-forming coating liquid containing a resin component and a light-transmitting particle is applied on a transparent substrate by a known coating method such as gravure coating and bar coating, and dried and cured as necessary. It can be formed by doing. In order to make it easy to make the strength ratio within the range of the present invention, it is preferable to contain inorganic ultrafine particles in the uneven layer-forming coating liquid.

Fig. 10 is a scanning transmission electron micrograph (STEM) showing a cross section of the concave-convex layer of the optical sheet of Example 1, which is formed by coating a coating solution for forming an uneven layer containing a binder resin, light-transmitting particles, and inorganic ultrafine particles. )to be.

Usually, the surface of the concave-convex layer becomes substantially smooth at the point where the translucent particle does not exist, but the concave-convex layer in Fig. 10 has a gentle slope at the point where the translucent particle does not exist. The reason is considered to be that the thixotropic property of the coating liquid and the drying property of the solvent are affected by the inorganic ultrafine particles, and leveling as usual does not occur. In this way, it is considered that by forming a gentle slope even at a location where the translucent particles do not exist, substantially smooth locations in the uneven layer are eliminated as much as possible, and the intensity ratio can be easily made within the scope of the present invention.

In addition, the concave-convex layer of FIG. 10 is made easy to make the surface haze, α, β, and γ within the above-described ranges by reducing the number of substantially smooth locations in the concave-convex layer as much as possible for the reasons (1) to (3) below and as described above. I think I can do it.

(1) Slightly steep inclination of the place where the translucent particle exists and the gentle inclination of the place where the translucent particle does not exist are mixed, and the inclination becomes a random irregularity shape.

(2) Usually, the shape of the periphery of the concave-convex layer of the light-transmitting particles present in the vicinity of the surface of the concave-convex layer is a convex shape according to the shape of the light-transmitting particle, but in the concave-convex layer of FIG. It is not made up of. In this way, the shape of the light-transmitting particles present in the vicinity of the surface of the uneven layer is not sufficiently reflected in the surface shape of the uneven layer, thereby resulting in a shape with less rapid unevenness.

(3) In the concave-convex layer of Fig. 10, both dispersion and aggregation exist in the light-transmitting particles. The reason is considered to be that the inorganic ultrafine particles have an influence on the thixotropy of the coating liquid and the affinity between the translucent particles. As such, the presence of both dispersion and agglomeration results in a random surface shape due to a large number of fluctuations in the uneven shape.

As the light-transmitting particle, either of a light-transmitting organic particle and a light-transmitting inorganic particle can be used. In addition, the light-transmitting particles may have shapes such as a spherical shape, a disk shape, a rugby hole shape, and an irregular shape. Further, hollow particles, porous particles, and solid particles of these shapes may be mentioned. Among these, spherical solid particles are suitable 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, fluorine-based resin and polyester-based Particles containing resin, etc. are mentioned.

Examples of the translucent inorganic particles include particles containing silica, alumina, zirconia, titania, and the like.

Among the above-described light-transmitting particles, light-transmitting organic particles are suitable from the viewpoint of easiness of dispersion control, and among them, polyacrylic-styrene copolymer particles are suitable. Polyacrylic-styrene copolymer particles are good in that they are easy to control internal haze and aggregation/dispersion because control of the degree of refractive index and hydrophilic number is easy. In addition, from the viewpoint of making the internal haze the range of the present invention, the difference in refractive index between the translucent particles and the binder resin is preferably 0.01 to 0.10.

The light-transmitting particles preferably have an average particle diameter of 2 to 10 µm, more preferably 3 to 8 µm, from the viewpoint of making the intensity ratio within the range of the present invention.

In addition, the ratio of the average particle diameter of the light-transmitting particles to the thickness of the uneven layer (average particle diameter of the light-transmitting particles/thickness of the uneven layer) is a viewpoint of making it easier to make the intensity ratio, surface haze, and α, β, and γ within the scope of the present invention. It is preferably 0.5 to 1.0, and more preferably 0.6 to 0.9.

The average particle diameter of the translucent particles can be calculated by the following operations (1) to (3).

(1) The optical sheet of the present invention is imaged with a transmission observation image under an optical microscope. The magnification is preferably 500 to 2000 times.

(2) Ten arbitrary particles are extracted from the observation image, individual particle long and short diameters are measured, and individual particle particle diameters are calculated from the average of the long and short diameters. The longest diameter is taken as the longest diameter on the screen of individual particles. Note that the short diameter refers to the distance between two points at which a line segment orthogonal to the midpoint of the line segment constituting the long diameter is drawn, and the orthogonal line segment intersects the particle.

(3) The same operation is performed 5 times in the observation image of another screen of the same sample, and the value obtained from the number average of the particle diameters for a total of 50 is taken as the average particle diameter of the translucent particles.

For the average primary particle diameter of the inorganic ultrafine particles, first, the cross section of the optical sheet of the present invention is imaged by TEM or STEM. After imaging, the average primary particle diameter of the inorganic ultrafine particles can be calculated by performing the same method as in the above (2) and (3). It is preferable that the acceleration voltage of TEM or STEM is 10 kV to 30 kV, and the magnification is 50,000 to 300,000 times.

The content of the light-transmitting particles is preferably 2 to 25% by mass of the total solid content forming the uneven layer from the viewpoint of making it easy to make the internal haze, the surface haze, and the intensity ratio, α, β, and γ within the scope of the present invention, It is more preferable that it is 5-20 mass %.

Examples of the inorganic ultrafine particles include ultrafine particles including silica, alumina, zirconia, titania, and the like. Among these, ultrafine silica particles are suitable from the viewpoint of transparency.

The inorganic ultrafine particles preferably have an average particle diameter of 1 to 25 nm, more preferably 5 to 20 nm, from the viewpoint of making the intensity ratio, surface haze, and α, β, and γ easily within the scope of the present invention.

The inorganic ultrafine particles are preferably reactive inorganic ultrafine particles into which a reactive group is introduced by surface treatment. By introducing a reactive group, it becomes possible to contain a large amount of inorganic ultrafine particles in the uneven layer, so that the intensity ratio, surface haze, and α, β, and γ can be easily set within the scope of the present invention.

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 ethylenically unsaturated bonds such as a (meth)acryloyl group, a (meth)acryloyloxy group, a vinyl group and an allyl group, and an epoxy group.

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, a dry method of spraying a silane coupling agent onto the inorganic ultrafine particles, or a wet method of adding a silane coupling agent to react after dispersing the inorganic ultrafine particles in a solvent may be mentioned.

The content of the inorganic ultrafine particles is preferably 10 to 90% by mass, more preferably 20 to 70% by mass, and still more preferably 35 to 50% by mass, based on the total solid content forming the uneven layer. By setting it as the said range, the intensity ratio, surface haze, α, β, and γ can be easily made into the ranges of the present invention by controlling the leveling property and suppressing the polymerization shrinkage of the uneven layer.

In addition, the ratio of the content of the translucent particles and the inorganic ultrafine particles in the uneven layer (the content of the translucent particles / the content of the inorganic ultrafine particles) is from the viewpoint of making it easier to make the intensity ratio, surface haze, and α, β and γ within the scope of the present invention. It is preferable that it is 0.1-0.4, and it is more preferable that it is 0.2-0.3.

The resin component of the concave-convex layer preferably contains a thermosetting resin composition or an ionizing radiation curable resin composition, and more preferably contains an ionizing radiation curable resin composition from the viewpoint of improving mechanical strength, and among them, an electron beam curable resin composition It is more preferable to include.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition cured by heating.

Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. To 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 ethylenically unsaturated bonding groups such as (meth)acryloyl group, vinyl group, and allyl group, and epoxy group and oxetanyl group. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenically unsaturated bond groups is more preferable, and among them, a polyfunctional (meth)acrylate type having two or more ethylenically unsaturated bond groups. Compounds are more preferred. As the polyfunctional (meth)acrylate-based compound, either a monomer or an oligomer can be used.

In addition, ionizing radiation means having both energy capable of polymerizing or crosslinking molecules among electromagnetic waves or charged particle rays. Usually, ultraviolet rays (UV) or electron rays (EB) are used, but in addition to X-rays, γ-rays Electromagnetic waves such as, α rays, and charged particle rays such as ion rays can also be used.

Among the polyfunctional (meth)acrylate-based compounds, examples of the bifunctional (meth)acrylate-based monomer include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxy diacrylate, bisphenol A tetrapropoxy diacrylate, 1, 6-hexanediol diacrylate, etc. are mentioned.

Examples of trifunctional or higher (meth)acrylate-based monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa (Meth)acrylate, dipentaerythritol tetra(meth)acrylate, isocyanuric acid-modified tri(meth)acrylate, etc. are mentioned.

In addition, the (meth)acrylate-based monomer may be one having a part of the molecular skeleton modified, and modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, etc. It is also possible to use those made of this.

Further, 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. I can.

Urethane (meth)acrylate is obtained, for example, by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth)acrylate.

In addition, preferred epoxy (meth)acrylates are (meth)acrylates obtained by reacting (meth)acrylic acid with trifunctional or higher aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc., bifunctional or higher aromatic epoxy resins, alicyclic epoxy resins. (Meth)acrylate obtained by reacting a polybasic acid and (meth)acrylic acid with resins, aliphatic epoxy resins, etc., and a (meth)acrylate obtained by reacting phenols with (meth)acrylic acid, such as a bifunctional or higher aromatic epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin. ) It is an acrylate.

The ionizing radiation curable compound may 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 an additive such as a photoinitiator or a photopolymerization accelerator.

As a photoinitiator, one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl methyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthone, etc. are mentioned. I can.

It is preferable that these photoinitiators have a melting point of 100°C or higher. By setting the melting point of the photopolymerization initiator to be 100°C or higher, it is possible to prevent the photopolymerization initiator from sublimating during formation of the transparent conductive film of the touch panel or due to heat in the crystallization step, and damage to the low resistance of the transparent conductive film.

In addition, the photopolymerization accelerator is one that can speed up the curing rate by reducing polymerization inhibition by air during curing, and for example, 1 selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. More than a species can be mentioned.

The thickness of the uneven layer is preferably 2 to 10 µm, more preferably 4 to 8 µm from the viewpoint of curl suppression, mechanical strength, hardness, and balance of toughness.

The thickness of the concave-convex layer can be calculated from the average value of the values at 20 locations by measuring the thickness of 20 locations from an image of a cross section taken using, for example, a scanning transmission electron microscope (STEM). The acceleration voltage of the STEM is preferably 10 kV to 30 kV, and the magnification is 1000 to 7000 times.

In the uneven layer-forming coating liquid, a solvent is usually used to adjust the viscosity or to dissolve or disperse each component. Depending on the type of solvent, the surface condition of the uneven layer after application and drying process is different (in other words, because the strength ratio, surface haze, and values of α, β and γ are different), the saturated vapor pressure of the solvent, and the transparent substrate It is desirable to select a solvent in consideration of the permeability of the solvent, etc.

Specifically, solvents are, 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, cyclo Hexanol), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.) It can be illustrated, and a mixture of these may be sufficient.

When the drying of the solvent is too slow or too fast, the leveling property of the uneven layer is excessive or insufficient, making it difficult to adjust the strength ratio, surface haze, and values of α, β, and γ to the above-described ranges. Therefore, as a solvent, it is preferable to contain 50 mass% or more of a solvent with a relative evaporation rate (relative evaporation rate when the evaporation rate of n-butyl acetate is 100) in the total solvent from 100 to 180. It is more preferable that a relative evaporation rate is 100-150 as a solvent of 50 mass% or more in all solvents.

For example, toluene is 195, methyl ethyl ketone (MEK) is 465, methyl isobutyl ketone (MIBK) is 118, and propylene glycol monomethyl ether (PGME) is 68.

In addition, the type of solvent also affects the dispersibility of inorganic ultrafine particles represented by silica ultrafine particles. For example, MIBK is suitable because it is excellent in dispersibility of inorganic ultrafine particles, and it is easy to adjust the strength ratio, surface haze, and α, β, and γ in the above-described ranges.

In addition, from the viewpoint of making it easy to make the strength ratio, surface haze, and α, β, and γ in the above-described ranges, it is preferable to control the drying conditions when forming the uneven layer. Drying conditions can be controlled by the drying temperature and the wind speed in the dryer. As a specific drying temperature, it is preferable to set it as 30 to 120 degrees, and 0.2 to 50 m/s as a drying wind speed. Further, in order to control the leveling of the concave-convex layer according to the drying conditions, irradiation of ionizing radiation is preferably performed after drying.

In addition, from the viewpoint of smoothing the surface irregularities appropriately so that the strength ratio, surface haze, and α, β, and γ are easily within the above-described ranges, it is preferable to contain a leveling agent in the coating liquid for forming the irregularities layer. The leveling agent may be fluorine-based or silicone-based, and a silicone-based leveling agent is suitable. 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 liquid.

As the transparent substrate of the optical sheet, it is preferable that it has light transmittance, smoothness, and heat resistance, and has excellent mechanical strength. Examples of such transparent substrates include polyester, triacetylcellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, And plastic films such as polyether ketone, acrylic, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP). The transparent substrate may be one obtained by bonding two or more plastic films.

Among the above, from the viewpoint of mechanical strength and dimensional stability, polyester (polyethylene terephthalate, polyethylene naphthalate) subjected to stretching processing, particularly biaxial stretching processing, is preferable. Further, TAC and acrylic are suitable from the viewpoint of light transmittance and optical isotropy. Moreover, COP and polyester are suitable because 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 1/4 wavelength retardation can prevent a stain of a different color from being observed on the display screen when an image of a liquid crystal display is observed through polarized sunglasses. It is suitable in point.

The thickness of the transparent substrate is preferably 5 to 300 µm, more preferably 30 to 200 µm.

On the surface of the transparent base material, in addition to physical treatment such as corona discharge treatment, oxidation treatment, etc., in order to improve adhesion, a coating material called an anchor agent or a primer may be applied in advance.

The optical sheet may have a functional layer such as an antireflection layer, an antifouling layer, and an antistatic layer on the uneven shape and/or on the surface opposite to the uneven shape. Further, in the case of a configuration having an uneven layer on the transparent substrate, a functional layer may be provided between the transparent substrate and the uneven layer in addition to the above locations.

[Display device]

The display device of the present invention is a display device comprising an optical sheet on a front surface of a display element having a pixel density of 300 ppi or higher, wherein the optical sheet has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface Haze is 22 to 40%, and visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the transmitted light is constant from the surface having the uneven shape. The strength of the angular range is measured, and the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction is extrapolated to the forward transmission angle, and the strength at -2° with respect to the forward transmission direction. When the average value of the intensity obtained by extrapolating the straight line connecting the intensity and the intensity at -1° by the forward transmission angle is "imaginary intensity in the forward transmission direction", the relationship of the following formula (I) is satisfied.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

Ultra-high-precision display devices with a pixel density of 300 ppi or more tend to cause glare as described above, but in the present invention, by using a specific optical sheet as an optical sheet having an uneven shape, while providing various properties such as anti-glare properties, ultra-high-precision display It is possible to prevent the image light of the device from flashing and deterioration of resolution.

As the optical sheet used for the display device of the present invention, the same optical sheet used for the touch panel of the present invention described above can be used.

Examples of the display device include a liquid crystal display device, an in-cell touch panel liquid crystal display device, an EL display device, and a plasma display device.

In the in-cell touch panel liquid crystal element, a touch panel function such as a resistive film type, a capacitive type, and an optical type is incorporated inside a liquid crystal element formed by sandwiching a liquid crystal between two glass substrates. In addition, 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. The in-cell touch panel liquid crystal element is described in, for example, Japanese Patent Application Laid-Open No. 2011-76602 and Japanese Patent Application Laid-Open No. 2011-222009.

The optical sheet can be provided, for example, on the front surface of the display element in the following order.

(1) Display element/surface protection plate/optical sheet

(2) Display element/optical sheet

(3) Display element/optical sheet/surface protection plate

(4) Touch panel having a display element/optical sheet as a constituent member

In the case of (1) and (2), by arranging the uneven surface of the optical sheet to face the surface (the uneven surface faces the opposite side of the display element), high anti-glare properties can be imparted and glare can be prevented. It can, and furthermore, it is possible to prevent deterioration of the resolution. Further, in the case of this method of use, it is possible to make it difficult to see the scratches generated on the surface or the display element.

In the case of (3), by arranging the optical sheet as in the embodiment of the touch panel of the present invention described above, it is possible to prevent glare while imparting various properties such as anti-glare properties.

In the case of (2) and (4), if the uneven surface of the optical sheet faces toward the display element and is disposed through the air layer, adhesion and interference fringes are prevented, and scratches generated on the display element are difficult to see. I can.

The optical sheet used in the display device of the present invention can suppress reflection of external light even in an outdoor bright environment, and can impart a high degree of anti-glare property. Since portable information terminals represented by recent smartphones are often used outdoors, it is preferable to use the display device of the present invention with the optical sheet facing the viewer side (the side opposite to the display element). Do.

[Optical sheet]

The optical sheet of the present invention is an optical sheet having an uneven shape on one side, and the optical sheet has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and a surface having an uneven shape of the optical sheet and Is irradiated with visible light perpendicular to the optical sheet from the opposite side direction, and the intensity of the transmitted light in a certain angular range from the side having an uneven shape is measured, and the intensity at +2° with respect to the forward transmission direction The straight line connecting the strength at +1° is extrapolated to the forward transmission angle, and the straight line connecting the strength at -2° and the strength at -1° with respect to the forward transmission direction is extrapolated to the forward transmission angle. When the average value of the intensity is "virtual intensity in the normal transmission direction", the relationship of the following formula (I) is satisfied, and is used for the front surface of a display element having a pixel density of 300 ppi or more.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

Examples of the optical sheet of the present invention include those similar to the optical sheet used for the touch panel of the present invention described above.

The optical sheet of the present invention is preferably used on the front surface of a display device having a pixel density of 300 ppi or more, thereby imparting various properties such as anti-glare properties, while preventing glare of image light and deterioration in resolution of the ultra-high-precision display device. .

Further, the optical sheet of the present invention can suppress reflection of external light even in an outdoor bright environment, and can impart a high degree of anti-glare property. Since portable information terminals represented by recent smartphones are often used outdoors, the optical sheet of the present invention has a concave-convex surface on the outermost surface of a touch panel or display device. It is preferable to use it facing up.

[Selection method of optical sheet]

The optical sheet sorting method of the present invention is a sorting method of an optical sheet having an uneven shape on one side, and (a) satisfies the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%. In addition, (b) visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the transmitted light is in a certain angle range from the surface having the uneven shape. The strength was measured and the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction was extrapolated by the forward transmission angle, and the strength at -2° with respect to the forward transmission direction and- When the average value of the intensity obtained by extrapolating the straight line connecting the intensity at 1° by the normal transmission angle is referred to as ``virtual intensity in the normal transmission direction'', the pixel density that satisfies the following formula (I) as an optical sheet is selected as an optical sheet. This is a method for selecting an optical sheet used on the front surface of a display device of 300ppi or more.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

In the optical sheet sorting method of the present invention, even if the optical sheet is not incorporated in the display device, when used in an ultra-high precision display element having a pixel density of 300 ppi or more, an optical sheet capable of preventing glare and deterioration of resolution can be selected, The quality control of the optical sheet can be performed efficiently.

The judgment conditions for selecting the optical sheet are essential conditions that (a) satisfy 5 to 30% of the internal haze or 22 to 40% of the surface haze of the optical sheet, and (b) satisfy the following formula (I). .

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

The internal haze of the determination condition (a) is preferably 5 to 25%, more preferably 10 to 18%. The surface haze of the determination condition (a) is preferably 25 to 40%, more preferably 25 to 35%.

As for the determination condition (b), it is preferable that 1.0≦intensity ratio≦3.5, more preferably 1.0≦intensity ratio≦2.0, and still more preferably 1.0≦intensity ratio≦1.5.

Further, by setting one or more selected from the following conditions (c) to (e) as the determination condition, it is possible to more accurately select an optical sheet capable of preventing glare and lowering of resolution. As for the conditions (c) to (e), it is preferable to use two or more as the determination conditions, and more preferably, all three as the determination conditions.

(c) The diffusion angle representing the intensity of 1/2 of the imaginary intensity in the forward transmission direction is referred to as "α", and the absolute value of α is 1.4 to 3.0°.

(d) The diffusion angle representing the intensity of 1/3 of the imaginary intensity in the forward transmission direction is referred to as "β", and the absolute value of β is 1.9 to 5.0°

(e) The diffusion angle representing the intensity of 1/10 of the imaginary intensity in the forward transmission direction is referred to as "γ", and the absolute value of γ is 3.5 to 8.0°

In condition (c), the absolute value of α is more preferably 1.5 to 3.0°, and still more preferably 1.7 to 2.5°.

In condition (d), the absolute value of β is more preferably 2.0 to 4.5°, and still more preferably 2.3 to 4.0°.

In condition (e), the absolute value of γ is more preferably 4.0 to 7.5°, and still more preferably 4.5 to 6.5°.

Further, by setting one or more selected from the following conditions (f) to (h) as the determination condition, it is possible to more accurately select an optical sheet capable of preventing glare and lowering of resolution. As for the conditions (f) to (h), it is preferable to use two or more as the determination conditions, and more preferably, all three as the determination conditions.

(f) 2.0°≤|γ|-|α|≤5.0° (Ⅱ)

(g) 1.5°≤|γ|-|β|≤4.0° (Ⅲ)

(h) 0.5°≤|β|-|α|≤2.0° (Ⅳ)

In condition (f), it is more preferable that |γ|-|α| is 2.5° or more and 4.0° or less. Moreover, in condition (g), it is more preferable that |γ|-|β| is 2.0 degrees or more and 3.5 degrees or less. Further, under condition (h), it is more preferable that |β|-|α| is 0.6° or more and 1.5° or less.

[Method of manufacturing optical sheet]

The manufacturing method of the optical sheet of the present invention is a manufacturing method of an optical sheet having an uneven shape on one side, and (a) satisfies the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%. In addition, (b) visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the transmitted light is in a certain angle range from the surface having the uneven shape. The strength was measured and the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction was extrapolated by the forward transmission angle, and the strength at -2° with respect to the forward transmission direction and- When the average value of the intensity obtained by extrapolating the straight line connecting the intensity at 1° by the forward transmission angle is referred to as the "virtual intensity in the temporary forward transmission direction", a display with a pixel density of 300 ppi or more is prepared to satisfy the following formula (I). It is a manufacturing method of an optical sheet used for the front surface of an element.

1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

In the manufacturing method of the optical sheet of the present invention, it is essential to control the manufacturing conditions so as to satisfy the conditions (a) and (b). The suitable range of conditions (a) and (b) is the same as the method for selecting the optical sheet described above. As an additional condition for the manufacturing method of the optical sheet of the present invention, it is preferable to control the manufacturing conditions so as to satisfy the conditions (c) to (h) of the method for selecting an optical sheet described above.

The optical sheet manufacturing method of the present invention can provide various characteristics such as anti-glare properties, and efficiently prevents glare of image light and deterioration of resolution of an ultra-high-precision display device having a pixel density of 300 ppi or more. Can be manufactured.

The internal haze of the manufacturing condition (a) can be controlled by adjusting the internal diffusion element as described above. The surface haze of the manufacturing condition (a) can be controlled by adjusting the surface diffusion element as described above. Further, in the adjustment of the surface diffusion element, it is preferable to mix various inclination angles, and in order to do so, it is preferable to introduce a control means for the production condition (b) described later.

The manufacturing condition (b) can be controlled by increasing the ratio of the diffusion elements of the uneven layer and reducing the ratio of the light passing right through. For this purpose, it is preferable to eliminate substantially smooth locations in the uneven layer as much as possible, and make it a shape in which substantially the whole of the uneven layer becomes an inclined surface. The specific means for controlling the manufacturing condition (b) is to control the shape of the mold when the uneven layer is formed by a mold. In addition, specific means for controlling the production conditions (b) in the case of forming the uneven layer by coating are to use an appropriate amount of inorganic ultrafine particles as described above, to use a solvent with a specific range of relative evaporation rate, and to dry Adjusting drying conditions, such as temperature and wind speed, and using an appropriate amount of a leveling agent are mentioned.

The manufacturing conditions (c) to (h) can be controlled by mixing various inclination angles including an inclination having a large inclination angle, rather than simply making the uneven surface of the optical sheet a gentle inclination. Specific means for controlling the manufacturing conditions (c) to (h) include the same means as the means exemplified in the means for controlling the manufacturing conditions (b).

[Example]

Next, the present invention will be described in more detail by examples, but the present invention is not limited at all by these examples. In addition, "part" and "%" are based on mass unless otherwise specified.

1. Measurement and evaluation of physical properties of optical sheet

Physical properties of the optical sheets of Examples and Comparative Examples were measured and evaluated as follows. Table 1 shows the results.

[Haze]

First, haze (total haze) was measured according to JIS K-7136:2000 using a haze meter (HM-150, manufactured by Murakami Shikisai Kijutsu Kenkyusho). In addition, by attaching a TAC film with a thickness of 80 μm (manufactured by Fujifilm, TD80UL) through a transparent adhesive to the surface of the optical sheet, the uneven shape is crushed and flattened, while removing the effect of haze due to the surface shape. Haze was measured and internal haze (Hi) was determined. And the internal haze value was subtracted from the total haze value, and the surface haze (Hs) was calculated|required. The light incident surface was made into the substrate side.

[Strength ratio]

On the surface of each optical sheet obtained in Examples and Comparative Examples on the side opposite to the surface on which the antiglare layer (corrugated layer) was formed, a transparent adhesive was interposed and attached to a glass plate to obtain a sample. According to the method described in the text of the specification, using a variable angle photometer (GC-5000L, manufactured by Nippon Denshoku Kogyo Co., Ltd.), the light source angle is set to 0° and the sensitivity setting is set to 1000 times by transmission measurement, and the sample is taken with the glass surface as the light source side. After installation, the intensity of the transmitted light of the optical sheet is measured every 1°, and an intensity distribution map of the transmitted light is created by linear interpolation, and the ratio (intensity ratio) of [intensity in the forward transmission direction/imaginary intensity in the forward transmission direction], α , β and γ were calculated. In addition, the strength was measured in the range of ±20° in the forward transmission direction. In addition, the value of the intensity is a value when the intensity of the normal transmitted light (a light-receiving angle of 0°) when no sample is provided as a reference value is 100000.

[Three-dimensional average tilt angle of optical sheet]

Samples were obtained by attaching to a glass plate through a transparent adhesive on the surface of each optical sheet obtained in Examples and Comparative Examples opposite to the surface on which the antiglare layer (uneven layer) is formed, and a white interference microscope (New View 7300, Zygo) was used to measure and analyze the surface shape of the optical sheet under the following conditions. In addition, Microscope Application of Metro Pro ver 8.3.2 was used as measurement and analysis software.

(Measuring conditions)

Objective lens: 50 times

Zoom: 1x

Measurement area: 414 μm×414 μm

Resolution (interval per point): 0.44㎛

(Interpretation conditions)

Removed: None

Filter: Band Pass

Filter Type: Gauss Spline

Low wavelength: 800㎛

High wavelength: 3㎛

Remove spikes: on

Spike Height(xRMS): 2.5

In addition, the low wavelength corresponds to the cut-off value λc in the illuminance parameter.

Next, the Slope Mag Map screen was displayed with the analysis software (Metro Pro ver 8.3.2-Microscope Application), and the histogram was displayed as nBins=100 in the screen to obtain histogram data of the three-dimensional surface inclination angle distribution. The width of the section of each class angle in the histogram was 0.5° or less.

Assuming that the i-th class representative angle of the histogram data is θ _i and the frequency is f _i , the three-dimensional average inclination angle m is calculated by the following equation (4).

Here, N is the total number of data, and it is calculated from the following equation (5).

[Ra, Rz, Smp of optical sheet]

"Ra" and "SRz" were displayed on the Surface Map screen under the surface shape data obtained when calculating the above-described surface inclination angle distribution and the same analysis conditions, and each numerical value was referred to as Ra and Rz of the optical sheet.

Next, a "Save Data" button was displayed on the Surface Map screen, and the analyzed 3D curved surface roughness data was saved. Then, the above stored data was read with the Advanced Texture Application, and the following analysis conditions were applied.

(Interpretation conditions)

High FFT Filter: off

Low FFT Filter: off

·Remove: Plane

Next, the Peak/Valleys screen was displayed, and the number of floors was counted from “Peaks Stats”. However, since fine floors are excluded, floors with an area ^{of 1/10000 or more of the area (414×414 μm 2} ) of the entire measurement area and 1/10 or more of Rtm were counted as targets. Rtm can be read from the "Roughness/Waviness Map" screen, and represents the average of the maximum height for each area when the entire measurement area is divided into 3×3. And Smp was calculated based on the above equation (3).

[flash]

In each of the optical sheets obtained in Examples and Comparative Examples, the surface of the optical sheet on which the anti-glare layer was not formed and the glass surface on which the black matrix (glass thickness of 0.7 mm) was not formed were bonded with a transparent pressure-sensitive adhesive. With respect to the sample thus obtained, a white surface light source (manufactured by HAKUBA, LIGHTBOX, average luminance of 1000 cd/m 2) was provided on the black matrix side, thereby causing pseudo flash. This was taken from the optical sheet side with a CCD camera (KP-M1, C mount adapter, macro ring; PK-11A Nikon, camera lens; 50 mm, F1.4s NIKKOR). The distance between the CCD camera and the optical sheet was 250 mm, and the focus of the CCD camera was adjusted according to the optical sheet. An image photographed with a CCD camera was introduced into a personal computer, and analysis was performed as follows with image processing software (ImagePro Plus ver. 6.2; manufactured by Media Cybernetics).

First, an evaluation point of 200 x 160 pixels was selected from the introduced image, and converted into a 16-bit gray scale at the evaluation point. Next, a low-pass filter was selected from the highlight tab of the filter command, and the filter was installed under the conditions of "3 x 3, number of times 3, intensity 10". Thereby, the component derived from the black matrix pattern was removed. Next, flattening was selected, and shading correction was performed under the conditions of "background: darkness, object width 10". Next, contrast enhancement was performed with "contrast: 96, luminance: 48" as the contrast enhancement command. The obtained image was converted into an 8-bit gray scale, and the deviation of the value for each pixel for 150 x 110 pixels was calculated as a standard deviation value, thereby digitizing the glare. It can be said that the smaller the numerical value of the glare, the less the glare. In addition, evaluation was performed in two ways, that the black matrix had a pixel density equivalent to 350 ppi and a pixel density equivalent to 200 ppi.

[Anti-glare]

On the substrate side of the obtained optical sheet, a black acrylic plate was placed on a horizontal surface and a sample for evaluation bonded via a transparent adhesive was placed on a horizontal surface, and a fluorescent lamp was placed 1.5 m above the sample for evaluation, and the fluorescent lamp was transferred onto the sample for evaluation. In addition, sensory evaluation was performed visually at various angles under an environment in which the illuminance on the evaluation sample was set to 800 to 1200 Lx, and evaluated according to the following criteria.

A: The image of a fluorescent lamp cannot be recognized from any angle.

B: The image of the fluorescent lamp is projected, but the outline of the fluorescent lamp is blurred, and the boundary of the outline cannot be recognized.

C: The image of the fluorescent lamp is projected like a mirror surface, and the outline (the boundary of the outline) of the fluorescent lamp can be clearly recognized.

[Contrast (dark room)]

In the measurement of the contrast ratio, using a light source with a diffusion plate installed on a cold cathode tube light source as a backlight unit, and using two polarizing plates (AMN-3244TP manufactured by Samsung Corporation), the luminance of light that passes when the polarizing plate is installed in a parallel Nicol By dividing the phosphorus L _max by the luminance of light passing through the cross nicol, L _{min , the contrast (L 1} ) when the anti-glare film (light-transmitting substrate + anti-glare layer) is placed on the outermost surface (L 1) and light transmittance. The contrast ratio was calculated by calculating the contrast _{(L 2} ) when only the substrate was placed on the outermost surface, and calculating (L ₁ /L _{2 )×100 (%).}

In addition, for the measurement of luminance, a color luminance meter (BM-5A manufactured by Topcon Corporation) was used, and it was carried out in a dark room environment with an illuminance of 5 Lx or less. The measurement angle of the chromatic luminance meter was set to 1°, and the field of view φ 5 mm was measured from the vertical direction on the sample. The amount of light of the backlight was set so that the luminance when two polarizing plates were installed on the parallel Nicole in a state where no sample was provided was 3600 dB/m 2.

[Total light transmittance]

The total light transmittance of the optical sheet was measured in accordance with JIS K7361-1:1997 using a haze meter (HM-150, manufactured by Kijutsu Kenkyusho Murakami Shikisai). The light incident surface was made into the substrate side.

[Transmission Clarity]

Four types of transmission image clarity through optical combs having widths of 2 mm, 1 mm, 0.5 mm and 0.125 mm in accordance with JIS K7105:1981 using a Suga Shikenki Co., Ltd. filamentity measuring device (brand name: ICM-1T) Was measured, and the sum of them was calculated.

[all sorts of flowers]

A sample obtained by bonding the surface of the optical sheet on the transparent substrate side and a black acrylic plate through a transparent pressure-sensitive adhesive was prepared. With respect to the prepared sample, a cloudy feeling was observed in a dark room under a tabletop stand using a 3-wavelength fluorescent lamp as a light source according to the following criteria.

A: No white was observed.

C: White was observed.

[Visibility of scratches]

The uneven surface of the optical sheet of the sample produced in the evaluation of whitening was rubbed once with a steel wool of #0000 under a load of about 100 g/cm 2, and scratches on the surface were visually evaluated. As a result, it was set as "A" that the flaw was not conspicuous and that the flaw was conspicuous as "C".

[Interference stripes]

The two optical sheets were superimposed so that the uneven surface side of one optical sheet and the transparent substrate side of the other optical sheet were opposed. As a result, it was set as "A" that the interference fringe did not occur, and "C" that the interference fringe occurred.

2. Preparation of optical sheet

[Example 1]

Apply the anti-glare layer coating solution 1 of the following prescription on a transparent substrate (thickness 80 μm triacetylcellulose resin film (TAC), manufactured by Fujifilm, TD80UL), and after drying for 30 seconds at 70°C and a wind speed of 5 ㎧, UV rays Was irradiated in a nitrogen atmosphere (oxygen concentration 200 ppm or less) so that the accumulated light amount was 100 mJ/cm 2 to form an anti-glare layer (corrugated layer) to obtain an optical sheet. The film thickness of the anti-glare layer was 7.5 µm. In addition, Ra on the side opposite to the uneven layer of the optical sheet was 0.02 µm.

<Antiglare layer coating liquid 1>

10 parts of pentaerythritol triacrylate

(KAYARAD-PET-30, manufactured by Nippon Kayaku)

・Urethane acrylate

(Nippon Kosei Chemical Co., Ltd. UV1700B) 45 copies

·Photopolymerization initiator 3 parts

(Manufactured by BASF, Irgacure 184)

0.2 parts of silicone leveling agent

(Momentive Performance Materials, TSF4460)

12 parts of translucent particles

(Spherical polyacrylic-styrene copolymer manufactured by Sekisui Kaseihin Co., Ltd.)

(Average particle diameter 6㎛, refractive index 1.535)

·Weapon ultra-fine particles 160 copies

(Made by Nissan Chemical Co., Ltd., silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)

(Average primary particle diameter of 12 nm)

110 parts of solvent 1 (MIBK)

[Example 2]

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

[Example 3]

An optical sheet was obtained in the same manner as in Example 1 except that the translucent particles of Example 1 were changed to 15 parts and the inorganic ultrafine particles were changed to 150 parts.

[Comparative Example 1]

An optical sheet was obtained in the same manner as in Example 1, except that the anti-glare layer coating liquid 1 of Example 1 was changed to the anti-glare layer coating liquid 2 of the following formulation, and the film thickness of the anti-glare layer (corrugated layer) was 2 µm.

<Antiglare layer coating liquid 2>

100 parts of pentaerythritol triacrylate

(KAYARAD-PET-30, manufactured by Nippon Kayaku)

・14 parts of inorganic fine particles

(Made by Fuji Silysia Chemical Co., Ltd., gel-method amorphous silica)

(Hydrophobic treatment, average particle diameter (laser diffraction scattering method) 4.1 µm)

5 parts photopolymerization initiator

(Manufactured by BASF, Irgacure 184)

0.2 parts of silicone leveling agent

(TSF4460 manufactured by Momentive Performance Materials)

・150 parts of solvent 1 (toluene)

Solvent 2 (MIBK) 35 parts

[Comparative Example 2]

An optical sheet was obtained in the same manner as in Example 1 except that the anti-glare layer coating solution 1 of Example 1 was changed to the anti-glare layer coating solution 3 of the following formulation, and the film thickness of the anti-glare layer (corrugated layer) was 4.5 μm. .

<Antiglare layer coating liquid 3>

・90 parts of pentaerythritol triacrylate

(KAYARAD-PET-30, manufactured by Nippon Kayaku)

·Acrylic polymer

(Mitsubishi Rayon company make, molecular weight 75,000) 10 parts

·Photopolymerization initiator 3 parts

(Manufactured by BASF, Irgacure 184)

0.1 part of silicon-based leveling agent

(TSF4460 manufactured by Momentive Performance Materials)

12 parts of translucent particles

(Soken Chemical Co., Ltd., spherical polystyrene particles)

(Particle diameter 3.5㎛, refractive index 1.59)

Solvent 1 (toluene) 145 parts

Solvent 2 (cyclohexanone) 60 parts

[Comparative Example 3]

An optical sheet was obtained in the same manner as in Example 1, except that the anti-glare layer coating liquid 1 of Example 1 was changed to the anti-glare layer coating liquid 4 of the following formulation, and the film thickness of the anti-glare layer (corrugated layer) was 7.0 µm.

<Antiglare layer coating liquid 4>

38 parts of pentaerythritol triacrylate

(KAYARAD-PET-30, manufactured by Nippon Kayaku)

・Isocyanuric acid EO-modified triacrylate

(Manufactured by Doa Kosei, M-313) 22 copies

5 parts photopolymerization initiator

(Manufactured by BASF, Irgacure 184)

0.1 part of silicon-based leveling agent

(Momentive Performance Materials, TSF4460)

20 parts of translucent particles

(Spherical polyacrylic-styrene copolymer manufactured by Sekisui Kaseihin Co., Ltd.)

(Particle diameter 5㎛, refractive index 1.525)

·Weapon Ultrafine Particles 120 copies

(Made by Nissan Chemical Co., Ltd., silica containing reactive functional groups on the surface, solvent MIBK, solid content 30%)

(Average primary particle diameter of 12 nm)

135 parts of solvent 1 (toluene)

[Comparative Example 4]

An optical sheet was obtained in the same manner as in Example 1 except that the anti-glare layer coating liquid 1 of Example 1 was changed to the anti-glare layer coating liquid 5 of the following formulation, and the film thickness of the anti-glare layer (corrugated layer) was set to 5.0 µm.

<Antiglare layer coating liquid 5>

38 parts of pentaerythritol triacrylate

(KAYARAD-PET-30, manufactured by Nippon Kayaku)

・Isocyanuric acid EO-modified triacrylate

(M-313 manufactured by Doa Kosei Co., Ltd.) 22 copies

5 parts photopolymerization initiator

(Manufactured by BASF, Irgacure 184)

0.1 part of silicon-based leveling agent

(TSF4460 manufactured by Momentive Performance Materials)

12 parts of translucent particles

(Spherical polyacrylic-styrene copolymer manufactured by Sekisui Kaseihin Co., Ltd.)

(Particle diameter 3.5㎛, refractive index 1.545)

·Weapon Ultrafine Particles 120 copies

(Made by Nissan Chemical Co., Ltd., silica containing reactive functional groups on the surface, solvent MIBK, solid content 30%)

(Average primary particle diameter of 12 nm)

135 parts of solvent 1 (toluene)

As revealed from the results of Table 1, the optical sheets of Examples 1 to 3 can impart various properties such as anti-glare properties, and can prevent glare of ultra-high-precision display devices having a pixel density of 300 ppi or more, and further The contrast was also excellent. In addition, the optical sheets of Examples 1 to 3 exhibited extremely better effects than the optical sheets of Comparative Examples 1 to 4 with respect to the anti-glare properties of the display elements with a pixel density of 350 ppi, but the anti-glare performance of the display elements with a pixel density of 200 ppi. About this, the difference in effect with the optical sheet of Comparative Examples 1-4 is small. In this regard, it can be seen that the optical sheets of Examples 1 to 3 are extremely useful for ultra-high precision display devices having a pixel density of 300 ppi or more. In addition, the above-described evaluation of anti-glare property was performed in an environment with an illuminance of 800 to 1200 Lx, but the optical sheets of Examples 1 to 3 had good anti-glare properties even in an outdoor environment with an illuminance of 10000 Lx or more.

3. Fabrication 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 sputtering to obtain an upper electrode plate. Next, an ITO conductive film having a thickness of about 20 nm was formed on one side of a tempered glass plate having a thickness of 1 mm by a sputtering method to obtain a lower electrode plate. Subsequently, on the side of the lower electrode plate having the conductive film, an ionizing radiation curable resin (Dot Cure TR5903: Taiyo Ink Co., Ltd.) as a coating solution for spacers was printed in dot form by screen printing, and then irradiated with ultraviolet rays with a high-pressure mercury lamp. , Spacers having a diameter of 50 µm and a height of 8 µm were arranged at intervals of 1 mm.

Then, the upper electrode plate and the lower electrode plate were arranged so as to face each other, and the edges were adhered with a double-sided adhesive tape having a thickness of 30 μm and a width of 3 mm, and the resistive film type of Examples 1 to 3 and Comparative Examples 1 to 4 A touch panel was produced.

The obtained resistive touch panel was mounted on a commercially available ultra-high-precision liquid crystal display device (pixel density 350 ppi), and the presence or absence of glare was visually evaluated.The touch panels of Examples 1 to 3 suppressed glare and projected external light. There were few, and visibility was good. In addition, the touch panels of Examples 1 to 3 did not impair the ultra-high-precision image resolution, and had good contrast in a bright room environment. On the other hand, the touch panels of Comparative Examples 1 to 4 had remarkable glare. Further, in the touch panel of Comparative Example 2, since the internal haze of the optical sheet was relatively high, the ultra-high-precision image resolution was slightly impaired.

4. Fabrication of display device

The optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4 and a commercially available ultra-high-precision liquid crystal display device (pixel density 350 ppi) were bonded to each other through a transparent pressure-sensitive adhesive. A display device was fabricated. In addition, at the time of bonding, the uneven surface of the optical sheet was made to face the opposite side to the display element.

When the presence or absence of glare of the obtained display device was visually evaluated, glare was suppressed in the display devices of Examples 1 to 3, and there was little projection of external light, and the visibility was good. In addition, the display devices of Examples 1 to 3 did not impair the ultra-high-precision image resolution, and had good contrast in a bright room environment. On the other hand, the display devices of Comparative Examples 1 to 4 had remarkable glare. Further, in the display device of Comparative Example 2, since the internal haze of the optical sheet was relatively high, the ultra-high-precision image resolution was slightly impaired.

1: resistive 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 (11)

It is a touch panel having an optical sheet as a constituent member,
The optical sheet has an uneven layer comprising a binder resin, light transmitting particles and inorganic ultrafine particles, has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and further
Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,
The diffusion angle representing the luminance of 1/10 of the imaginary intensity in the forward transmission direction is referred to as "γ", and the absolute value of γ is 3.5 to 8.0°,
A touch panel used on the front surface of a display device with a pixel density of 300ppi or higher.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ) The method of claim 1,
A touch panel in which a diffusion angle indicating a luminance of 1/2 of the imaginary intensity in the forward transmission direction is referred to as "α", and an absolute value of α is 1.4 to 3.0°. The method according to claim 1 or 2,
A touch panel in which a diffusion angle indicating a luminance of 1/3 of the virtual intensity in the forward transmission direction is referred to as "β", and an absolute value of β is 1.9 to 5.0°. delete A display device comprising an optical sheet on a front surface of a display element having a pixel density of 300 ppi or more,
The optical sheet has an uneven layer comprising a binder resin, light transmitting particles and inorganic ultrafine particles, has an uneven shape on one side, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and further
Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,
The diffusion angle representing the luminance of 1/10 of the virtual intensity in the forward transmission direction is referred to as "γ", and the absolute value of γ is 3.5 to 8.0°,
Display device.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ) It is an optical sheet having an uneven shape on one side,
The optical sheet has a concave-convex layer comprising a binder resin, light-transmitting particles, and inorganic ultrafine particles, and has an internal haze of 5 to 30% or a surface haze of 22 to 40%, and
Visible light is irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the optical sheet, and the intensity of the transmitted light in a certain angular range from the surface having the uneven shape is measured. The strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the transmission direction by the forward transmission angle, and the strength at -2° and the strength at -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the connecting straight line by the forward transmission angle is “imaginary strength in the forward transmission direction”, the relationship of the following equation (I) is satisfied,
The diffusion angle representing the luminance of 1/10 of the imaginary intensity in the forward transmission direction is referred to as "γ", and the absolute value of γ is 3.5 to 8.0°,
Optical sheet used for the front surface of display devices with a pixel density of 300 ppi or higher.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ) The method of claim 6,
An optical sheet in which a diffusion angle indicating an intensity of 1/2 of the virtual intensity in the forward transmission direction is referred to as "α", and an absolute value of α is 1.4 to 3.0°. The method according to claim 6 or 7,
An optical sheet in which a diffusion angle indicating an intensity of 1/3 of the virtual intensity in the forward transmission direction is referred to as "β", and an absolute value of β is 1.9 to 5.0°. delete It is a method of sorting an optical sheet having an uneven shape on one side,
(a) the optical sheet has a concave-convex layer comprising a binder resin, light-transmitting particles and inorganic ultrafine particles, and satisfies the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%, and
(b) Irradiating visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the concave-convex shape of the optical sheet, and measuring the intensity in a certain angular range from the surface having the concave-convex shape of the transmitted light Thus, the strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction by the forward transmission angle, and the strength at -2° and -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the strength of the straight line connecting the strength of the forward transmission angle is referred to as “virtual strength in the forward transmission direction”, the following equation (I) is satisfied, and 1/10 of the virtual strength in the forward transmission direction. The diffusion angle representing the luminance of is referred to as "γ", and the absolute value of γ is selected as an optical sheet of 3.5 to 8.0°,
A method of sorting an optical sheet used for a front surface of a display device having a pixel density of 300 ppi or more.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ) It is a manufacturing method of an optical sheet having an uneven shape on one side,
(a) the optical sheet has a concave-convex layer comprising a binder resin, light-transmitting particles and inorganic ultrafine particles, and satisfies the condition that the internal haze of the optical sheet is 5 to 30% or the surface haze is 22 to 40%, and
(b) Irradiating visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the concave-convex shape of the optical sheet, and measuring the intensity in a certain angular range from the surface having the concave-convex shape of the transmitted light Thus, the strength obtained by extrapolating the straight line connecting the strength at +2° and the strength at +1° with respect to the forward transmission direction by the forward transmission angle, and the strength at -2° and -1° with respect to the forward transmission direction. When the average value of the strength obtained by extrapolating the strength of the straight line connecting the strength of the forward transmission angle is referred to as “virtual strength in the forward transmission direction”, the following equation (I) is satisfied, and 1/10 of the virtual strength in the forward transmission direction. The diffusion angle representing the luminance of is referred to as ``γ'', and the absolute value of γ is prepared so that it is 3.5 to 8.0°,
A method of manufacturing an optical sheet used for a front surface of a display device having a pixel density of 300 ppi or more.
1.0≤Intensity in forward transmission direction/Virtual intensity in forward transmission direction≤4.0 (Ⅰ)

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