JP2007249182A - Display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display which can improve viewing angle dependency of a contrast ratio at least in a specific azimuth without design change of a basic structure of a display element, limitation to white display state or black display state, and deterioration in display quality in other directions. <P>SOLUTION: The display comprises: a display element with a contrast ratio dependent on a viewing angle; and an anisotropic scattering film having an anisotropic scattering layer, wherein the anisotropic scattering film is located on a viewing screen side of the display element and has a scattering central axis in substantially the same azimuth as an azimuth in which a contrast ratio of the display element in a direction inclined by a certain angle from a normal direction of a viewing screen of the display element has a minimum value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a display device. More specifically, the present invention relates to a display device including a display device such as a liquid crystal display device and an anisotropic scattering film.

As a typical example of a display device having a viewing angle dependency (viewing angle characteristic) in display performance, a liquid crystal display device represented by a twisted nematic (TN) mode is known. “Display performance depends on viewing angle” means that the display is observed from the front direction (the normal direction of the viewing surface of the display device, the viewing angle is 0 °) and the oblique direction (the viewing angle is greater than 0 °). This means that the display performance such as contrast ratio, gradation characteristics, chromaticity, and the like is different from that observed from above. In general, it is known that these display performances are not better when observed from an oblique direction than when viewed from the front direction.

In the TN mode liquid crystal display device, the contrast ratio gradually decreases as the viewing angle increases in the vertical and horizontal directions (clockwise 3 o'clock / 6 o'clock / 9 o'clock / 12 o'clock). For example, even when the contrast ratio is 320 when observed from the front direction, when viewed from the viewing angle of 75 ° in the upward direction (12 o'clock direction), the observation is performed from the viewing angle of 50 ° in the downward direction (6 o'clock direction). In this case, the contrast ratio becomes 10 when the left direction (9 o'clock direction) is observed from a viewing angle of 65 ° and when the right direction (3 o'clock direction) is observed from a viewing angle of 68 °. The display color is neutral when observed from the front direction (no coloring occurs), but is yellowish when observed from the top, bottom, left, and right directions. In particular, when observed from the lower direction, an abnormal phenomenon of gradation characteristics called gradation reversal, which appears to be a negative / positive reversal of the display image, may be observed. The viewing angle dependency of the display performance in such a liquid crystal display device is due to the optical anisotropy of the component parts such as the refractive index anisotropy of the liquid crystal molecules and the polarization absorption characteristics and polarization transmission characteristics of the polarizing plate. It can be said that this is a characteristic inherent to a liquid crystal display device.

Various methods have been proposed so far for improving the viewing angle dependency of the display performance of the liquid crystal display device. Examples of such a method include a pixel division method (a halftone gray scale method in which one pixel is divided into a plurality of pixels and a voltage applied to each pixel is changed at a constant ratio, or one pixel is divided into a plurality of domains. There is a domain division method for controlling the alignment of the liquid crystal for each domain, etc.), in-plane switching (IPS) mode in which a horizontal electric field is applied to the liquid crystal, and vertical alignment when no voltage is applied. A display mode such as a multi-domain vertical alignment (MVA) mode for driving liquid crystal, an OCB (Optically Compensated Birefringence) mode in which a bend alignment cell and a retardation film are combined, and a retardation film are used. Optical compensation method Many of liquid crystal display devices that have already been commercialized adopt these methods.

However, when adopting the pixel division method or the above-described display mode, it is necessary to change the structure of the alignment film, the electrode, etc., and it is necessary to establish a manufacturing technique and newly install a manufacturing facility, resulting in difficult manufacturing. There was room for improvement in terms of cost and cost. Further, the effect of improving the viewing angle dependency is not sufficient. Furthermore, the optical compensation method using a retardation film has a limit in the improvement effect. For example, since the optimum phase difference value for the phase difference compensation of the liquid crystal cell differs between black display and white display, the phase difference compensation of the liquid crystal cell cannot be performed for both black display and white display. In addition, in the axial direction of the polarization axis (transmission axis and absorption axis) of the polarizing plate, the compensation effect by the retardation film cannot be obtained in principle, and the improvement effect is limited to a specific azimuth angle range. There was room for improvement.

In addition to the above, as a method of improving the viewing angle dependency of the display performance of the liquid crystal display device, a method of averaging the emitted light by providing a scattering film on the observation surface side of the liquid crystal display device is known. This method can be applied to all display modes, and basically no change in the structure of the display cell is required. In addition, unlike the optical compensation method using the above-described retardation film, an effect can be obtained in both black display and white display, and the effect is not lost even in the axial direction of the polarization axis of the polarizing plate.

As a light source of a normal liquid crystal display device, a diffusion backlight system that emits diffused light is used. Most liquid crystal display modes and polarizing plates have the best characteristics for vertically incident light, so the light from the diffuse backlight system is collimated as much as possible by a lens film, etc. Cell). Thereby, since it is possible to obtain a further effect of improving the viewing angle dependency, many techniques related to this have been proposed.

However, since a method for easily and efficiently obtaining parallel light has not yet been established, the method for improving the viewing angle dependency by the scattering film is substantially used in combination with the diffuse backlight system as described above. In that case, although the effect of improving the viewing angle dependency can be obtained as described above, in the black display state, part of the leaked light entering and exiting the liquid crystal cell is bent in the front direction by the scattering film. There is room for improvement in that light leakage increases in the front direction and the contrast ratio in the front direction is greatly reduced. This is because, since the scattering performance of the scattering film is isotropic, the scattering characteristics of the scattering film with respect to the transmitted light do not differ greatly even if the incident angle is slightly changed.

On the other hand, for a resin composition composed of a plurality of compounds having one or more photopolymerizable carbon-carbon double bonds in a molecule having a difference in refractive index, a predetermined angle range from a linear light source. A light control plate (for example, see Patent Documents 1 to 13) manufactured by irradiating ultraviolet rays and curing the resin composition, and a liquid crystal display device equipped with such a light control plate (for example, Patent Document) 14 and 15). Such a light control plate transmits light incident from an oblique direction and scatters light incident from the front direction, that is, selectively scatters light incident from the front direction. Therefore, it is considered that the use of this light control plate can eliminate the decrease in the contrast ratio in the front direction as described above to some extent.

However, in the resin cured product of the light control plate, as shown in FIG. 33, the light control plate 50 is refracted from the peripheral region so as to coincide with the length direction of the linear light source 51 disposed above when the light control plate 50 is manufactured. It is considered that plate-like regions 40 having different rates are formed in parallel to each other. For this reason, the incident angle dependence of the scattering characteristic exhibited by the light control plate 50 is rotated around the AA axis so that the peripheral regions in FIG. 33 and plate-like regions 40 having different refractive indexes appear alternately. Although it can be seen in some cases, it is hardly seen when it is rotated around the BB axis, which has no change in refractive index and is homogeneous.

FIG. 34 is a schematic diagram showing the incident angle dependence of the scattering characteristics shown by the light control plate 50 in FIG. The vertical axis indicates the amount of linear transmitted light (an amount of parallel light emitted in the same direction as the incident direction when a predetermined amount of parallel light is incident), which is an index indicating the degree of scattering, and the horizontal axis indicates the incident angle. Indicates. Further, a solid line and a broken line in FIG. 34 indicate cases where the light control plate 50 is rotated around the AA axis and the BB axis in FIG. 33, respectively. The sign of the incident angle indicates that the direction in which the light control plate 50 is rotated is opposite.
In the solid line in FIG. 34, the linear transmitted light amount decreases in the direction near 0 °, and the linear transmitted light amount increases in the direction where the incident angle is large. This means that when rotated about the AA axis, the light control plate 50 is in a scattering state for light in the front direction and in a transmission state for light in the oblique direction. is doing. However, the broken line in FIG. 34 shows that the amount of linear transmitted light remains small both in the front direction and in the oblique direction. This means that the light control plate 50 is in a scattering state regardless of the incident angle when rotated about the BB axis.

In this way, with the conventional light control plate, the anisotropic scattering characteristics (characteristics in which the scattering characteristics change when the incident angle is changed) can be obtained only in a specific direction, so that the effect of improving the viewing angle dependency is specified. It can be obtained only in the azimuth direction, and in other azimuth directions, light incident from an oblique direction is scattered almost uniformly regardless of the incident angle, so there is room for improvement in that the display quality in the other direction is deteriorated. there were.
Japanese Unexamined Patent Publication No. 63-309902 Japanese Patent Application Laid-Open No. 64-40903 Japanese Patent Laid-Open No. 64-40905 Japanese Patent Laid-Open No. 64-40906 JP-A-1-77001 Japanese Patent Laid-Open No. 1-1147405 JP-A-1-147406 JP-A-2-51101 JP-A-2-54201 Japanese Unexamined Patent Publication No. 2-67501 Japanese Patent Laid-Open No. 3-87701 Japanese Patent Laid-Open No. 3-109501 JP-A-6-9714 JP 7-64069 A JP 2000-180833 A

The present invention has been made in view of the above-mentioned present situation, and does not change the design of the basic structure of the display device, and is not limited to the white display state or the black display state, and impairs the display quality in other directions. An object of the present invention is to provide a display device that can improve the viewing angle dependency of the contrast ratio in at least a specific orientation.

The inventors of the present invention have made various studies on a display device including a display device whose contrast ratio has a viewing angle dependency and an anisotropic scattering film having an anisotropic scattering layer. First, the viewing angle of the contrast ratio of the display device. Focused on dependency. It is noted that display devices usually have an orientation in which the contrast ratio tends to decrease as the polar angle increases (an orientation with a narrow viewing angle) and an orientation that remains high (an orientation with a wide viewing angle). did. For example, in a typical VA mode liquid crystal display device, an upward direction (direction with an azimuth angle of 90 °), a downward direction (direction with an azimuth angle of 270 °), a left direction (direction with an azimuth angle of 180 °), and a right In the direction (direction where the azimuth angle is 0 °), the contrast ratio is maintained high even if the polar angle is increased, but the upper right direction (direction where the azimuth angle is 45 °) and the upper left direction (direction where the azimuth angle is 135 °). ), In the lower left direction (direction having an azimuth angle of 225 °) and in the lower right direction (direction having an azimuth angle of 315 °), the contrast ratio tends to decrease as the polar angle increases.

Next, the inventors focused on the scattering characteristics of an anisotropic scattering film having a scattering center axis. The anisotropic scattering film having the scattering central axis has an anisotropic scattering characteristic (a characteristic in which the scattering characteristic changes when the incident angle is changed) having a substantially symmetric property about the scattering central axis. Therefore, this anisotropic scattering film is an orientation in which the contrast ratio is minimized in the direction in which the axial orientation of the scattering central axis is inclined by a certain angle from the normal direction of the observation surface of the display device (an orientation with a narrow viewing angle. By placing it on the viewing surface side of the display device so that it substantially coincides with the “minimum azimuth”, light (black luminance) incident substantially parallel to the axial direction of the scattering center axis is centered on the scattering center axis. It was found that the viewing angle dependency of the contrast ratio can be improved at least in the minimum azimuth that substantially coincides with the axial direction of the scattering central axis. For example, when an anisotropic scattering film having a scattering center axis in the normal direction of the observation surface of the display device is arranged on the observation surface side of the display device, the direction of the polar angle 0 ° is centered in all directions. In addition, the effect of improving the viewing angle dependency of the contrast ratio can be obtained. In addition, an anisotropic scattering film having a scattering center axis in a direction inclined by 30 ° from the normal direction of the viewing surface of the display device is displayed so that the axis direction of the scattering center axis substantially coincides with the minimum direction of the display device. When the device is arranged on the observation surface side of the device, the effect of improving the viewing angle dependence of the contrast ratio can be obtained in the range of a large polar angle around the direction of the polar angle of 30 ° in the minimal azimuth.

Also, according to this anisotropic scattering film, unlike the conventional anisotropic scattering film that exhibits anisotropic scattering characteristics only in a specific orientation, anisotropic scattering characteristics are also exhibited in orientations other than the axial orientation of the scattering center axis. As shown, since light incident from a direction other than a direction substantially parallel to the axial direction of the scattering central axis is scattered only weakly, the scattering of light incident from the same direction reduces display quality in a direction with a large contrast ratio. It was found that it can be suppressed.

Furthermore, in a normal display device, each display performance such as gamma curve and chromaticity is optimally designed in the direction in which the contrast ratio is maximized, and the viewing angle dependency of these display performances is also the viewing angle dependency of the contrast ratio. The same tendency is shown. Accordingly, it has been found that the viewing angle dependency of each display performance such as a gamma curve and chromaticity can be improved at least in a minimal azimuth that substantially coincides with the axial direction of the scattering central axis. And, the effect of improving the viewing angle dependency of the display performance by the anisotropic scattering film is obtained without being limited to the white display state or the black display state, unlike the retardation film. It has been found that an arbitrary display device whose performance depends on the viewing angle can be obtained without changing the design of the basic structure of the display device. From the above, the present inventors have conceived that the above problems can be solved brilliantly, and have reached the present invention.

That is, the present invention is a display device comprising a display device having a viewing angle dependency in contrast ratio and an anisotropic scattering film having an anisotropic scattering layer, wherein the anisotropic scattering film is a display device. The display device is arranged on the observation surface side of the display device and has a scattering center axis in an orientation substantially coincident with an orientation in which a contrast ratio in a direction inclined by a certain angle from the normal direction of the observation surface is minimized.
The present invention is described in detail below.

The display device of the present invention includes a display device whose contrast ratio has a viewing angle dependency, and an anisotropic scattering film having an anisotropic scattering layer. In the display device, the contrast ratio has a viewing angle dependency. In the present specification, the display device is not particularly limited as long as it is a device for performing display, and examples thereof include a liquid crystal display device. The contrast ratio is one of display performances of a display device, and is usually represented by a value obtained by dividing the maximum luminance by the minimum luminance. The viewing angle dependency means that when observed from the front direction (normal direction of the viewing surface of the display device, the direction where the polar angle is 0 °) and when observed from the oblique direction (the direction where the polar angle is greater than 0 °). In addition, even if the polar angles are the same, it means that the display performance of the display device differs between when observed from one direction and when observed from another direction. Therefore, “contrast ratio has viewing angle dependence” is different from the case of observation from the front direction and the case of observation from an oblique direction, and from the case of observation from a certain direction even if the polar angles are the same. This means that the contrast ratio is different when observed from the direction.
The contrast ratio of the display device is usually larger as it is closer to the front direction, but may be vice versa.

The anisotropic scattering film has an anisotropic scattering layer. In the present specification, the anisotropic scattering layer is not particularly limited as long as it exhibits anisotropic scattering characteristics (characteristics in which scattering characteristics change when the incident angle is changed) in at least one orientation. . The azimuth indicates the in-plane direction of the film surface of the anisotropic scattering film or the observation surface of the display device, and is represented by an azimuth angle Φ (0 ° ≦ Φ <360 °). The incident angle means an angle formed by the normal direction of the film surface and the incident direction. As the form of the anisotropic scattering film, for example, a form consisting of only an anisotropic scattering layer, a form in which a transparent substrate is laminated on one side (observation surface side or back side) of the anisotropic scattering layer, anisotropic scattering The form which laminated | stacked the transparent base | substrate on the both sides (observation surface side and back side) of a layer is mentioned. The anisotropic scattering layer may have a single layer structure or a laminated structure.

As the transparent substrate, the higher the transparency, the better. Therefore, the total light transmittance (JIS K7361-1) of the transparent substrate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The haze value (JIS K7136) of the transparent substrate is preferably 3.0 or less, more preferably 1.0 or less, and further preferably 0.5 or less. Examples of the transparent substrate include a transparent plastic film and a glass plate, but a plastic film is preferable in terms of excellent thinness, lightness, impact resistance, and productivity. Examples of the plastic film material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polycarbonate (PC), polyarylate, polyimide (PI), aromatic polyamide, polysulfone (PS), Examples include polyethersulfone (PES), cellophane, polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), cycloolefin resin, etc. As the form of the plastic film, the above materials may be used alone or in combination. The form formed from a film, the form formed by laminating the above-mentioned film, and the like can be mentioned. The thickness of the transparent substrate is preferably 1 μm to 5 mm, more preferably 10 to 500 μm, and still more preferably 50 to 150 μm in consideration of use and productivity.

In the present invention, the anisotropic scattering film has a scattering center axis. In this specification, the scattering center axis is an axis whose anisotropic scattering characteristic is substantially symmetric with respect to the axial direction. In this specification, for example, as shown in FIG. 2B, the axial direction of the scattering central axis is from the back side to the observation surface side, and the normal direction of the film surface (Z-axis direction). Furthermore, it is assumed that the observation surface side faces from the back side. At this time, an angle ω formed by the axial direction of the scattering center axis S and the normal direction (Z-axis direction) of the film surface is also referred to as a polar angle of the scattering center axis S. When the scattering center axis S is inclined from the normal direction of the film surface (ω ≠ 0 °), for example, as shown in FIG. 2B, the axial direction S ₁ projected onto the film surface is shown. , And substantially coincides with the normal direction of the film surface (ω≈0 °), it is assumed that the axis direction S ₁ has all the directions. The shaft bearing S ₁ of the scattering center axis also assumed to have a predetermined orientation, the orientation of the axis orientation shall be determined in correspondence to the axial direction.

The anisotropic scattering film having the scattering central axis exhibits anisotropic scattering characteristics in all directions. Therefore, although the scattering characteristics of the anisotropic scattering film cannot be expressed uniquely, when the linear transmitted light amount is used as an index of the scattering characteristics, the anisotropic scattering film constituting the display device of the present invention The amount of linearly transmitted light changes substantially symmetrically about the scattering center axis. The linear transmitted light amount is the light amount of parallel light beams emitted in the same direction as the incident direction when a predetermined amount of parallel light beams are incident. Examples of the method for measuring the linear transmitted light amount include the method shown in FIG. In the method shown in FIG. 6, a light receiving unit (for example, goniophotometer) 30 is fixed at a position that receives straight light from a light source (not shown), and a test piece 10 a is disposed between the light source and the light receiving unit 30. . According to this method, for example, by rotating the test piece 10a around the LL axis (rotation axis), the incident angle in the MM azimuth (measurement azimuth) perpendicular to the LL axis in the film plane. The amount of linear transmitted light can be measured by changing. The measurement direction can be changed as appropriate by changing the rotation axis. Therefore, according to this method, the amount of linearly transmitted light in various directions can be measured.

In the present invention, the anisotropic scattering film has a scattering center axis in an orientation substantially coincident with an orientation (minimum orientation) in which a contrast ratio in a direction inclined by a certain angle from the normal direction of the viewing surface of the display device is minimized. And is arranged on the viewing surface side of the display device. According to this, since the minimum azimuth of the display device and the axial azimuth of the scattering center axis of the anisotropic scattering film substantially coincide with each other, light incident substantially parallel to the axial direction of the scattering center axis in the minimum azimuth ( (Black luminance) can be averaged by being scattered in all directions around the scattering central axis, so that the viewing angle dependency of the contrast ratio can be improved at least in the minimum azimuth. In addition, since the anisotropic scattering film exhibits anisotropic scattering characteristics in all directions as described above, light in a direction with a large incident angle deviated from the axial direction of the scattering central axis is scattered only weakly. Since most of the light can be transmitted, it is possible to suppress deterioration in display quality in a direction with a large contrast ratio due to scattering of incident light in the same direction.

Furthermore, in a normal display device, each display performance such as gamma curve and chromaticity is optimally designed in the direction in which the contrast ratio is maximized, and the viewing angle dependency of these display performances is also the viewing angle dependency of the contrast ratio. The same tendency is shown. Therefore, according to the present invention, the viewing angle dependency of each display performance such as a gamma curve and chromaticity can usually be improved. The operational effects of the present invention are not limited to the white display state or the black display state, but the basic structure is changed in design for any display device whose display performance has a viewing angle dependency. You can get without.

Hereinafter, the “direction in which the contrast ratio is minimized in the direction inclined by a certain angle from the normal direction of the observation surface of the display device (minimum direction)” will be specifically described with reference to FIGS. explain.
FIG. 1A is a schematic diagram for explaining “a direction inclined by a certain angle from the normal direction of the observation surface of the display device”.
In FIG. 1A, the dotted line indicates the direction of the polar angle Θ, and the dotted line arrow indicates the normal direction of the observation surface of the display device 15. “A direction inclined by a certain angle Θ from the normal direction of the viewing surface of the display device” means all directions D whose polar angle is Θ, and the direction D extends from the back side to the viewing side. It is suitable.
In addition, the normal direction of the observation surface of the display device 15 usually coincides with the normal direction (Z-axis direction) of the observation surface of the display device and the normal direction of the film surface of the anisotropic scattering film.

FIG. 1B is a schematic diagram illustrating the orientation of the display device.
As shown in FIG. 1B, the orientation of the display device 15 is represented by an azimuth angle Φ (0 ° ≦ Φ <360 °). In this specification, the direction of Φ = 0 ° is also referred to as the right direction, the direction of Φ = 90 ° is also referred to as the upward direction, the direction of Φ = 180 ° is also referred to as the left direction, and the direction of Φ = 270 °. Is also referred to as the downward direction. As can be seen from FIGS. 1A and 1B, the direction of the azimuth angle Φ and the polar angle −Θ (0 ° ≦ Θ <90 °) and the azimuth angle Φ + 180 ° (opposite the azimuth of the azimuth angle Φ) (Azimuth) and the direction of polar angle Θ completely coincides with each other. In the present specification, normally, by setting the numerical range of the polar angle to 0 ° or more, the azimuth of the azimuth angle Φ is distinguished from the azimuth of the azimuth angle Φ + 180 °. It is expressed as the direction of ° ≦ Φ <360 °) and polar angle Θ (0 ° ≦ Θ <90 °).

FIG.1 (c) is a schematic diagram explaining the minimum azimuth | direction of a display device.
“Minimum orientation of display device” means the orientation that corresponds to the bottom of the valley-shaped curve in the graph showing the azimuth angle dependency of the contrast ratio in a direction inclined at a certain angle from the normal direction of the viewing surface of the display device To do. For example, in FIG. 1C, B1 to B4 correspond to the minimum direction of the display device. The number of minimum orientations of the display device is not particularly limited, but is usually four. When the display device has two or more minimum orientations, the anisotropic scattering film only needs to have a scattering center axis in an orientation that substantially coincides with one of the minimum orientations of the display device. In addition, as a display device having four minimum directions, for example, a liquid crystal display in which a pair of polarizing plates are arranged on the front and back of a liquid crystal cell (crossed Nicols arrangement) so that the absorption axes (transmission axes) thereof are orthogonal to each other. Device. When such a liquid crystal display device is observed from an orientation that bisects the angle formed by the absorption axis and the transmission axis of the polarizing plate, when the viewing angle is tilted down (when the polar angle is increased) ), Since the angle formed by the absorption axes (transmission axes) is deviated from 90 °, the contrast ratio is lowered. Therefore, in such a case, it is considered that these four directions become the minimum directions. On the other hand, when observed from the axial direction of the absorption axis (transmission axis) of the polarizing plate, the angle between the absorption axes (transmission axes) does not deviate from 90 ° even if the viewing angle is tilted. Remains high. These four azimuths are azimuths (maximum azimuths) corresponding to the apexes of the mountain-shaped curve in the graph showing the azimuth angle dependency of the contrast ratio in a direction inclined at a certain angle from the normal direction of the observation surface of the display device. Conceivable.

When the display device is a VA mode or IPS mode liquid crystal display device, the minimum azimuth is preferably four azimuths of azimuth angles Φ = 45 °, 135 °, 225 °, and 315 °. When the display device is a liquid crystal display device of a TN mode and an OCB mode, the minimum azimuth is preferably four azimuths of azimuth angles Φ = 0 °, 90 °, 180 °, and 270 °.
In the present specification, “substantially coincidence” includes not only a coincidence state but also a state that can be equated with a coincidence state in view of the operational effects of the present invention. In addition, in this specification, “substantially parallel” includes not only a state of being parallel but also a state that can be equated with a state of being parallel in view of the operational effects of the present invention.

As described above, the scattering center axis may substantially coincide with the normal direction of the observation surface of the display device, and (ii) from the normal direction of the observation surface of the display device, You may incline in the direction which substantially corresponds. Therefore, the polar angle ω of the scattering central axis is not particularly limited as long as it is 0 ° or more and less than 90 °, but is preferably 0 ° or more and less than 60 °. Further, the polar angle ω of the scattering central axis is more preferably about 0 ° from the viewpoint of improving the display quality of a TN mode liquid crystal display device or the like, and display in a direction with a large polar angle in a specific orientation From the viewpoint of improving the quality, it is more preferably 30 ° or more and 50 ° or less.

In an anisotropic scattering film having a scattering center axis in a direction inclined from the normal direction of the observation surface of the display device, normally, the linear transmitted light amount is incident angle η (− 90 ° <η <90 °) is larger than the polar angle ω (0 ° ≦ ω <90 °) of the scattering central axis (ω <η <90 °) and smaller (−90 ° <η <ω). Depending on the angle of incidence. For example, according to an anisotropic scattering film having a scattering center axis in the direction of polar angle 30 °, as shown in FIG. 7, in the axial direction of the scattering center axis, linear transmission is performed in a direction where the polar angle is larger than 30 °. The amount of light changes so as to draw a small mountain as the incident angle increases, whereas in the direction where the polar angle is smaller than 30 °, it changes so as to draw a large mountain as the incident angle decreases. In the anisotropic scattering film having the scattering center axis in the direction inclined from the normal direction of the observation surface of the display device, the incident angle η (− 90 ° <η <90 °) in a direction larger than 0 ° and a direction smaller than 0 °, the amount of linear transmitted light changes substantially symmetrically depending on the incident angle. For example, according to the anisotropic scattering film having the scattering center axis in the direction of the polar angle 30 °, as shown in FIG. 7, in the direction perpendicular to the axial direction of the scattering center axis, the incident angle is larger than 0 °. In a small direction, the linearly transmitted light amount changes substantially symmetrically depending on the incident angle.

Although the arrangement | positioning form of the said anisotropic scattering film and a display device is not specifically limited, It is preferable that the anisotropic scattering film is bonded together by the display device. The method for attaching the anisotropic scattering film to the display device is not particularly limited, and examples thereof include a method using an adhesive and a method using a pressure-sensitive adhesive.

The configuration of the display device of the present invention is not particularly limited as long as it has the display device and the anisotropic scattering film as components, and may or may not have other components. It is not a thing.
In addition, the linear transmitted light amount in the axial direction of the scattering central axis of the anisotropic scattering film is preferably as small as possible from the viewpoint of effectively obtaining the effects of the present invention.

Hereinafter, preferred embodiments of the display device of the present invention will be described in detail.
The anisotropic scattering film may have a scattering center axis in an orientation substantially coincident with an orientation in which a contrast ratio is minimized in a direction inclined by a constant angle of 20 ° or more from the normal direction of the viewing surface of the display device. preferable. The anisotropic scattering film more preferably has a scattering center axis in an orientation that substantially coincides with an orientation in which the contrast ratio in a direction inclined by 45 ° from the normal direction of the observation surface of the display device is minimized. The minimum azimuth of the display device is measured by measuring the contrast ratio in a direction inclined by a certain angle (hereinafter also referred to as “measurement angle”) from the normal direction of the observation surface of the display device, for example, as shown in FIG. It can be obtained by creating a graph showing the azimuth dependence of the contrast ratio. In the present invention, the measurement angle is not particularly limited as long as it is larger than 0 ° and smaller than 90 °. However, as shown in FIG. 3, in a general display device such as a liquid crystal display device, when the measurement angle is about 10 °, the contrast ratio increases uniformly in all directions, and the maximum contrast ratio and It may be difficult to determine the minimum. From such a viewpoint, the measurement angle is preferably 20 ° or more, and more preferably 45 °.
Therefore, in the present invention, the axis direction of the scattering central axis may be substantially coincident with any one of the minimum orientations of the display device, but is substantially the same as the minimum orientation of the display device obtained at a constant angle of 20 ° or more. It is preferable that they coincide with each other, and more preferably substantially coincides with the minimum orientation of the display device obtained at a measurement angle of 45 °.
Note that the minimum azimuth of the display device may vary in number and azimuth depending on the measurement angle.

The anisotropic scattering layer is preferably formed by curing a composition containing a photocurable compound. According to this, the anisotropic scattering film which has the above-mentioned anisotropic scattering characteristic, ie, the anisotropic scattering film which shows an anisotropic scattering characteristic in all the directions, can be manufactured simply. The anisotropic scattering layer formed by curing the above composition may have a structure extending in an oblique direction, for example, when the cross section is observed with a microscope. In this case, as shown in FIG. 2A, it is considered that a large number of minute rod-shaped hardened regions 20 having a refractive index slightly different from the peripheral region are formed in an oblique direction inside the anisotropic scattering layer 10. It is done. In this case, as shown in FIG. 2B, the scattering center axis S of the anisotropic scattering film 10a constituting the display device of the present invention is the normal direction (Z-axis direction) of the observation surface of the display device. However, it is considered that the axial direction is parallel to the extending direction of the rod-shaped hardening region 20 in FIG. Furthermore, in this case, inclined scattering central axis S, as shown in FIG. 2 (b), has the axis direction S ₁ which is projected onto the X-Y plane, the axis orientation S ₁ rod-like It is considered that there is a parallel relationship with the direction of the shadow when the cured region 20 is projected onto the XY plane. Therefore, it is considered that the anisotropic scattering characteristics of the anisotropic scattering film described above are manifested due to the internal structure of the anisotropic scattering layer. In addition, in FIG. 2A, the shape of the rod-shaped hardened region 20 is represented as a cylindrical shape, but is not particularly limited. Moreover, in FIG. 2A, as one preferred example, the rod-shaped cured region 20 extends in an oblique direction, but the extending direction of the rod-shaped cured region 20 is the axial direction of the scattering center axis. Similarly, there is no particular limitation. Furthermore, the shape of the anisotropic scattering layer 10 is expressed in a sheet shape, but is not particularly limited.

As a form of the composition containing the photocurable compound, (A) a form of a photopolymerizable compound alone, (B) a form containing a mixture of a plurality of photopolymerizable compounds, (C) a single or a plurality of photopolymerizable compounds Examples include a form containing a mixture of a compound and a polymer resin not having photopolymerizability. According to the embodiments (A) to (C), as described above, a micron-order microstructure (rod-like hardened region) having a refractive index different from that of the peripheral region is formed in the anisotropic scattering layer by light irradiation as described above. As a result, it is considered that the incident angle dependence of the above-mentioned linear transmitted light amount can be expressed.

Therefore, the single photopolymerizable compound in the forms (A) and (C) preferably has a large refractive index change before and after photopolymerization. Moreover, as a some photopolymerizable compound in the form of said (B) and (C), the combination from which the refractive index after hardening differs is preferable. Furthermore, the photopolymerizable compound in the form (C) and the polymer resin not having photopolymerizability are preferably combinations having different refractive indexes after curing. From the viewpoint of effectively obtaining the effects of the present invention, the refractive index change and the difference in refractive index are preferably 0.01 or more, more preferably 0.05 or more, and 0.10. It is still more preferable that it is above.

Further, the photocurable compound includes a photopolymerizable compound (radical polymerizable compound or cationic polymerizable compound) of a polymer, oligomer or monomer having a radical polymerizable or cationic polymerizable functional group, and a photoinitiator, It is preferable to have a property of being polymerized and cured by irradiation with ultraviolet rays and visible rays.

The radically polymerizable compound mainly contains one or more unsaturated double bonds in the molecule, and specifically, for example, in the name of epoxy acrylate, urethane acrylate, polyester acrylate, silicone acrylate, etc. Acrylic oligomer called 2-ethylhexyl acrylate, phenoxyethyl acrylate, isonorbornyl acrylate, 2-hydroxyethyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2-perfluorooctyl-ethyl acrylate, triethylene glycol diacrylate Acrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, trimethylolpropane triacrylate, ethylene oxide (EO) modified trimethylolpropane triacrylate Acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, include acrylate monomers such as dipentaerythritol hexaacrylate.

As the cationically polymerizable compound, a compound containing at least one epoxy group, vinyl ether group, and / or oxetane group in the molecule can be used. Examples of the compound containing an epoxy group in the molecule include bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetrachlorobisphenol A, and tetrabromobisphenol. Diglycidyl ethers of bisphenols such as A, phenol novolak, cresol novolak, polyglycidyl ethers of novolak resins such as brominated phenol novolak, orthocresol novolak, ethylene glycol, butanediol, 1,6-hexanediol, neopentyl Diglycidyl ethers of alkylene glycols such as glycols, trimethylolpropane, ethylene oxide (EO) adducts of bisphenol A, Glycidyl esters of hexa hydro phthalic acid, glycidyl esters such as diglycidyl ester of dimer acid and the like. Furthermore, alicyclic epoxy compounds such as 3,4-epoxycyclohexanemethyl-3 ′, 4′-epoxycyclohexylcarboxylate, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 3- Oxetane compounds such as ethyl-3- (hydroxymethyl) -oxetane, vinyl ether compounds such as diethylene glycol divinyl ether, trimethylolpropane trivinyl ether, and the like can also be used.

The photopolymerizable compound is not limited to those described above. In order to cause a sufficient difference in refractive index, fluorine atoms (F) may be introduced into the photopolymerizable compound in order to reduce the refractive index, and in order to increase the refractive index. , Sulfur atoms (S), bromine atoms (Br), and various metal atoms may be introduced. In order to increase the refractive index of the anisotropic scattering layer, a super-refractive index metal oxide such as titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tin oxide (SnO _x ) or the like is used. It is also effective to add to the photopolymerizable compound functional ultrafine particles in which photopolymerizable functional groups such as acrylic groups and epoxy groups are introduced on the surface of the fine particles.

Examples of the photoinitiator capable of polymerizing the radical polymerizable compound include, for example, benzophenone, 2,4-diethylthioxanthone, benzoin isopropyl ether, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2,2-dimethoxy- 1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholinopropanone-1,1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (cyclopentadienyl) -bis (2 , 6-Difluoro-3- (pyr-1-yl) titanium, 2-benzyl-2-di Chiruamino -1- (4-morpholinophenyl) - butanone -1,2,4,6- trimethyl benzoyl diphenyl phosphine oxide, and the like.

The photoinitiator capable of polymerizing the cationic polymerizable compound is a compound that generates an acid by light irradiation and can polymerize the cationic polymerizable compound with the generated acid. Onium salts and metallocene complexes are preferably used. As the onium salt, a diazonium salt, a sulfonium salt, an iodonium salt, a phosphonium salt, a selenium salt, or the like is used. Tetrafluoroborate ion (BF ₄ ⁻ ), hexafluorophosphate ion (PF ₆ ) are used as these counter ions. ^-), hexafluoroarsenate ion (AsF ₆ ^-), hexafluoroantimonate ion (SbF ₆ ^-) anion and the like are used. Photoinitiators of cationic polymerizable compounds include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-methoxyphenyl) phenyliodonium hexafluoroantimonate, bis (4-t-butylphenyl) iodonium hexa Fluorophosphate, (η5-isopropylbenzene) (η5-cyclopentadienyl) iron (II) hexafluorophosphate, and the like.

The photoinitiator is preferably blended in an amount of 0.01 to 10 parts by weight with respect to 100 parts by weight of the photopolymerizable compound. If the photoinitiator is less than 0.01 part by weight, the photocurability may be reduced, and if it exceeds 10 parts by weight, only the surface may be cured and the internal curability may be reduced. It is. The photoinitiator is preferably blended in an amount of 0.1 to 7 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the photopolymerizable compound. More preferably.

Examples of the polymer resin having no photopolymerization in the form (C) include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, And vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, and the like. These polymer resins must have sufficient compatibility with the photopolymerizable compound before photopolymerization. In order to ensure such compatibility, various organic solvents and plastics are required. It is also possible to use an agent or the like. In addition, when using an acrylate as a photopolymerizable compound, it is preferable that polymer resin is selected from an acrylic resin from a compatible viewpoint.

The method for curing the composition is not particularly limited. For example, a method of providing the composition in a sheet form on a substrate and irradiating it with a parallel light beam (ultraviolet light or the like) from a predetermined direction can be mentioned. Thereby, the aggregate | assembly (for example, refer Fig.2 (a)) of the some rod-shaped hardening area | region extended in parallel with the irradiation direction of a parallel light beam can be formed.

As a method of providing the composition in a sheet form on the substrate, a normal coating method (coating) or printing method can be used. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse roll coating, transfer roll coating, gravure roll coating, kiss roll coating, cast coating, spray coating, slot orifice coating, calendar coating, dam coating, Coating methods such as dip coating and die coating, intaglio printing such as gravure printing, and printing methods such as stencil printing such as screen printing can be used. Moreover, when the viscosity of the said composition is low, the structure of providing predetermined structure around the base | substrate and apply | coating a liquid composition to the area | region enclosed with this structure can also be used.

As a light source used for irradiating the parallel light (ultraviolet rays or the like), a short arc ultraviolet lamp is usually used. Specifically, a high pressure mercury lamp, a low pressure mercury lamp, a metahalide lamp, a xenon lamp, or the like is used. Can do. The device used for irradiating parallel rays (ultraviolet rays, etc.) from a predetermined direction is not particularly limited, but can irradiate parallel ultraviolet rays of uniform intensity over a certain area, and can be selected from commercially available devices. Therefore, it is preferable to use an exposure apparatus for resist exposure. When forming an anisotropic scattering layer with a small size, it is also possible to use a method of irradiating from a sufficiently long distance using an ultraviolet spot light source as a point light source.

The parallel rays irradiated to the sheet of the composition must include a wavelength capable of polymerizing and curing the photopolymerizable compound, and is usually a wavelength centered at 365 nm of a mercury lamp. Are used. When forming an anisotropic scattering layer with light in this wavelength band, illuminance, 0.01 mW / cm ² or more and 100 mW / cm ² or less. If the illuminance is less than 0.01 mW / cm ² , it takes a long time to cure, which may deteriorate the production efficiency. If the illuminance exceeds 100 mW / cm ² , the photopolymerizable compound is cured too quickly to form a structure. This is because there is a possibility that desired anisotropic scattering characteristics cannot be expressed. The illuminance is more preferably 0.1 mW / cm ² or more and 20 mW / cm ² or less.

The anisotropic scattering film has a direction in which the linear transmitted light amount is equal to or less than the linear transmitted light amount in the axial direction of the scattering central axis, and the direction in which the linear transmitted light amount is equal to or less than the linear transmitted light amount is a normal to the observation surface of the display device It is preferable that the contrast ratio in a direction inclined by a certain angle from the direction coincides with the azimuth in which the contrast ratio is minimized. The direction in which the linearly transmitted light amount is equal to or smaller than the linearly transmitted light amount in the axial direction of the scattering center axis is usually close to the axial direction of the scattering center axis and is arranged substantially radially about the axial direction of the scattering center axis. . According to this, it is possible to obtain an operational effect equal to or greater than that obtained when the axis direction of the scattering central axis is matched with the minimum direction of the display device.

FIG. 4 is an explanatory diagram showing the relationship between the axis direction of the scattering center axis of the anisotropic scattering film constituting the display device of the present invention and the minimum direction of the display device. Note that two solid arrows in the figure represent the minimum orientation M _I1 of the display device and the axis orientation S ₁ of the scattering center axis, respectively. A represents the angle formed between the minimum azimuth M _I1 of the display device and the azimuth of the display device at an azimuth angle of 0 °, and δ represents the minimum azimuth M _I1 of the display device and the axis azimuth S ₁ of the scattering center axis. Indicates the angle to make.
Hereinafter, the display device of the present invention will be described with reference to FIG. 4, but the display device of the present invention is not limited to the configuration of FIG. For example, the arrangement relationship between the minimum orientation M _I1 of the display device and the axis orientation S ₁ of the scattering center axis is not limited to the relationship shown in FIG.

The axis direction of the scattering central axis is an angle (δ) of 15 ° or less with the direction (minimum direction) at which the contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device. Preferably there is. If the angle between the axis direction of the scattering center axis and the minimum direction of the display device exceeds 15 °, the amount of black luminance to be scattered is reduced, and it may be difficult to obtain the effect of improving the contrast ratio.

For example, the anisotropic scattering film showing the scattering characteristics in FIG. 5 is similar to or less than the axial direction of the scattering central axis (direction of the incident angle of 0 °) in the direction where the incident angle is in the range of −15 to 15 °. The amount of linear transmitted light is shown. Therefore, by setting the angle (δ) between the axis direction of the scattering center axis and the minimum direction of the display device to be 15 ° or less, the anisotropic scattering film has a display device that substantially matches the axis direction of the scattering center axis. Since sufficient diffusion performance can be exhibited in the minimum orientation, the effects of the present invention can be obtained. As shown in FIG. 5, in the direction where the incident angle exceeds the range of −15 to 15 °, the linear transmitted light amount is larger than the linear transmitted light amount in the axial direction of the scattering central axis. Therefore, when the angle (δ) between the axis orientation of the scattering center axis and the minimum orientation of the display device exceeds 15 °, the anisotropic scattering film causes the minimum orientation of the display device that substantially matches the axis orientation of the scattering center axis. However, sufficient diffusion performance cannot be exhibited, and the viewing angle dependency of the contrast ratio of the display device may appear as the viewing angle dependency of the contrast ratio of the display device as it is in the minimum orientation.

As for the axis direction of the scattering central axis, an angle (δ) formed with a direction (minimum direction) at which the contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device is 10 ° or less. More preferably, it is 5 ° or less. As a result, the axial orientation of the scattering center axis more closely matches the minimal orientation of the display device, so that the maximum contrast ratio and the contrast ratio in directions other than the minimal orientation substantially coincident with the axial orientation of the scattering central axis are not greatly reduced. The viewing angle dependence of the contrast ratio can be further improved at least in the minimum azimuth of the display device that substantially coincides with the axis orientation of the scattering central axis.

The axis direction of the scattering central axis is an angle (δ) formed by a direction in which the contrast ratio is minimized in a direction inclined by 20 ° or more from the normal direction of the observation surface of the display device is 15 ° or less. It is more preferable that the angle (δ) formed with an orientation at which the contrast ratio is minimized in a direction inclined by 45 ° from the normal direction of the observation surface of the display device is 15 ° or less.

In the anisotropic scattering film, the angle formed between the direction in which the linear transmitted light amount is minimum and the axial direction of the scattering center axis is greater than the angle formed in the direction where the linear transmitted light amount is maximum and the axial direction of the scattering center axis. Small is preferable. This is 0 when the angle between the direction in which the linear transmitted light amount is minimum and the axial direction of the scattering center axis is α, and the angle between the direction in which the linear transmitted light amount is maximum and the axial direction of the scattering center axis is β. It is represented by ° ≦ α <β. Usually, the direction in which the contrast ratio of the display device is large has a smaller polar angle than the direction in which the contrast ratio is small. Therefore, according to this, since the light in the direction in which the contrast ratio of the display device is large is scattered more strongly than the light in the direction in which the contrast ratio is small, the effect of the present invention can be obtained more effectively. As a more preferable form of the anisotropic scattering film, the graph showing the incident angle dependency of the scattering characteristics in the figure showing the incident angle-linear transmitted light amount is (i) a form having a substantially W shape (for example, FIG. 5), and (ii) a substantially U-shaped form. Hereinafter, an anisotropic scattering film having the form (i) and having a scattering central axis in the normal direction of the film surface will be described as an example.

In the case of the anisotropic scattering film having the form (i) and having the scattering center axis in the normal direction of the film surface, the linear transmitted light amount is the axial direction of the scattering center axis (the normal direction of the film surface). Although it is sufficiently small, it gradually decreases as the angle formed by the axial direction of the scattering central axis (incident angle magnitude) is larger, and the minimum value is obtained when the incident angle magnitude is 5 to 20 ° (α). Show. In the direction where the incident angle is larger than α, the linear transmitted light amount increases as the incident angle increases, and the maximum value is obtained when the incident angle is 40 to 65 ° (β). Indicates. And in the direction where the magnitude of the incident angle is larger than β, the linear transmitted light amount becomes smaller as the magnitude of the incident angle becomes larger. The incident angle dependence of the scattering characteristic is obtained in substantially the same manner in all directions. That is, the diagram showing the incident angle-linear transmitted light amount shows the scattering central axis (axis of incident angle 0 °). At the center, it shows a substantially symmetric property (for example, see FIG. 5).
In addition, the axial direction of the scattering central axis and the range of the incident angle where the linear transmitted light amount is the minimum value or the maximum value are examples, and are not limited thereto. In the form (i), the smaller the amount of linear transmitted light in the axial direction of the scattering central axis, the better. The form in which the linear transmitted light quantity is minimized in the axial direction of the scattering central axis is the form (ii). .

The incident angle dependence of the scattering characteristics of the anisotropic scattering film having the form (ii) above is represented by a vector starting from one exit point with the amount of linearly transmitted light and the traveling direction of incident light in all directions, When connecting and representing the tip portions of the vectors, as shown in FIG. 32, it is preferable to obtain a bell-shaped curved surface (broken line in the figure) having the symmetric central axis as the axial direction of the scattering central axis. The anisotropic scattering film exhibits the anisotropic scattering characteristics as described above, so that the reduction in the maximum contrast ratio can be made particularly small, and the viewing angle characteristics of the contrast ratio can be improved over a wide range including the minimum direction. Can do. Further, the effect of improving the viewing angle dependency of the contrast ratio can be obtained uniformly in all directions. Furthermore, the above-described effects can be obtained by matching the normal direction of the observation surface of the display device with the normal direction of the film surface of the anisotropic scattering film, that is, by bonding the display device and the anisotropic scattering film. Since it can obtain, the effect mentioned above can be obtained easily.

In the forms (i) and (ii) above, the range of the incident angle where the linear transmitted light amount is not more than a predetermined value may be widened. According to this, since the light in a wide range where the contrast ratio of the display device is large is scattered more strongly than the light in the direction where the contrast ratio is small, the effect of the present invention can be obtained more effectively. .

In the anisotropic scattering film, the angle formed by the direction in which the linear transmitted light amount is minimum and the axial direction of the scattering center axis is preferably close to 0 °. The minimum value of the linear transmitted light amount is preferably 50% or less, more preferably 30% or less of the maximum value in the figure showing the incident angle-linear transmitted light amount (for example, see FIG. 5). Preferably, it is more preferably 20% or less.

In the anisotropic scattering film, it is preferable that the polar angle in the direction in which the linear transmitted light amount is minimum is smaller than the polar angle in the direction in which the linear transmitted light amount is maximum in any orientation. Usually, the direction in which the contrast ratio of the display device is large has a smaller polar angle than the direction in which the contrast ratio is small. Therefore, according to this, in the above direction, the light in the direction in which the contrast ratio of the display device is large is scattered more strongly than the light in the direction in which the contrast ratio is small, so that the effect of the present invention can be obtained more effectively. Can do.
From the viewpoint of obtaining the effects of the present invention more effectively, the anisotropic scattering film has a polar angle in the direction in which the linear transmitted light amount is minimized in all directions, and the polar angle in the direction in which the linear transmitted light amount is maximized. More preferably, it is smaller than the corner.

The anisotropic scattering film has an axial orientation of the scattering center axis, and the maximum linear transmission light amount in the direction where the polar angle is larger than the scattering center axis is the linear transmission light amount in the direction where the polar angle is smaller than the scattering center axis. It is preferably smaller than the maximum value. In this embodiment, the “direction in which the polar angle is larger than the scattering center axis” means that the orientation is the same as the axial direction of the scattering center axis and the polar angle is larger than the polar angle of the scattering center axis. The direction in which the polar angle is smaller than the scattering center axis is not only the direction in which the orientation is the same as the axial orientation of the scattering center axis and the polar angle is smaller than the polar angle of the scattering center axis, but also the orientation is scattered The direction opposite to the axial direction of the central axis is also included. In the present invention, the anisotropic scattering film is arranged such that the axis direction of the scattering central axis substantially coincides with the maximum direction of the display device. Therefore, according to this, by diffusing light (black luminance) in the direction with a large contrast ratio around the scattering center axis without impairing the display quality in the direction opposite to the axis direction of the scattering center axis, The viewing angle dependence of the contrast ratio can be further improved in the minimum azimuth of the display device that substantially coincides with the axial azimuth of the axis.

As a more preferable form of the anisotropic scattering film, (iii) the polar angle in the direction in which the linear transmitted light amount is minimized in the direction perpendicular to the axial direction of the scattering central axis is the direction in which the linear transmitted light amount is maximized. A form smaller than the polar angle is mentioned. According to this aspect, it is possible to improve the display quality in the minimum azimuth of the display device that substantially matches the axis orientation of the scattering center axis without impairing the display quality in the orientation perpendicular to the axis orientation of the scattering center axis. The form (iii) will be described using FIG. 7 as an example. Note that the axial direction of the scattering central axis and the range of incident angles at which the amount of linear transmitted light shows the minimum value or the maximum value are examples, and are not limited to those shown in FIG.

FIG. 7 is a diagram showing an example of the incident angle dependence of the scattering characteristics of the anisotropic scattering film constituting the display device of the present invention.
In the anisotropic scattering film shown in FIG. 7, the polar angle ω of the scattering central axis is 30 °. That is, in the anisotropic scattering film of FIG. 7, since the polar angle ω of the scattering center axis is large, the incident angle dependence of the linear transmitted light amount is greatly different between the axis direction of the scattering center axis and the direction perpendicular to the axis direction. .

First, the incident angle dependence of the scattering characteristics in the axial direction of the scattering center axis will be described. In the direction where the polar angle is larger than the scattering center axis, the amount of linearly transmitted light is sufficiently small in the axial direction of the scattering center axis (incident angle is 30 °), but gradually decreases as the incident angle increases. The angle is minimum in the direction of 30-40 °. In the direction where the incident angle is larger than 30 to 40 °, the linearly transmitted light amount becomes larger as the incident angle becomes larger, and becomes maximum in the direction where the incident angle is 50 to 60 °. In the direction where the incident angle is larger than 50 to 60 °, the linearly transmitted light amount decreases as the incident angle increases. Further, in the direction where the polar angle is smaller than the scattering central axis, the direction gradually decreases as the incident angle becomes smaller, and becomes the smallest in the direction of 15 to 25 °. In the direction where the incident angle is smaller than 15 to 25 °, the smaller the incident angle, the larger the amount of linear transmitted light, and the maximum in the direction where the incident angle is −55 to −45 °. In the direction where the incident angle is smaller than −55 to −45 °, the linearly transmitted light amount becomes smaller as the angle becomes smaller.

Next, the incident angle dependence of the scattering characteristics in the direction perpendicular to the axial direction of the scattering central axis will be described. In this azimuth, the linearly transmitted light amount has a similar tendency between the direction in which the incident angle is larger than 0 ° and the direction in which the incident angle is smaller. The amount of linear transmitted light becomes minimum when the incident angle is in the direction of 0 to 10 °. In the direction where the incident angle is larger than 0 to 10 °, the linear transmitted light amount becomes larger as the incident angle becomes larger, and becomes the maximum in the direction where the incident angle is 55 to 65 °. In the direction in which the incident angle is larger than 55 to 65 °, the linear transmitted light amount decreases as the angle increases.

From the viewpoint of effectively obtaining the effects of the present invention, the linear transmitted light amount in the axial direction of the scattering center axis is preferably as small as possible, and the linear transmitted light amount may be minimized in the axial direction of the scattering center axis.

The display device is preferably a liquid crystal display device. As a result, it is possible to reduce the thickness and weight of the display device and reduce power consumption, and to improve the viewing angle dependency of the contrast ratio in the minimum azimuth of the liquid crystal display device that substantially matches the axis orientation of the scattering center axis. it can. Therefore, the display device of the present invention can be suitably used for car navigation or the like that requires high visibility in a specific direction such as the direction of the driver's seat.
The liquid crystal display device may be a transmissive liquid crystal display device, a transflective (semi-transmissive) liquid crystal display device, or a reflective liquid crystal display device.

The liquid crystal display device preferably includes a liquid crystal cell having a liquid crystal sandwiched between a pair of substrates, a polarizing plate including a support film and a polarizing element. The liquid crystal display device having such a form exhibits the viewing angle dependency of the contrast ratio due to at least the refractive index anisotropy of the liquid crystal and the polarization absorption property and polarization transmission property of the polarizing plate. Therefore, the viewing angle dependency of the contrast ratio of the liquid crystal display device can be improved by disposing the anisotropic scattering film on the viewing surface side of such a liquid crystal display device. As described above, in a liquid crystal display device in which a pair of polarizing plates are arranged on the front and back of a liquid crystal cell (crossed Nicols arrangement) so that the absorption axes (transmission axes) thereof are orthogonal to each other, the liquid crystal display device is usually used. The minimum azimuth corresponds to four azimuths that bisect the angle formed by the absorption axis and the transmission axis of the polarizing plate.

The form of the liquid crystal cell is not particularly limited, and examples thereof include a form having a liquid crystal sandwiched between a thin film transistor array substrate and a color filter substrate. In addition, the form of the polarizing plate is not particularly limited, but the form including the polarizing element and the support film from the liquid crystal cell side, the form including the support film and the polarizing element from the liquid crystal cell side, and the liquid crystal cell side The form which contains a 1st support film, a polarizing element, and a 2nd support film in order is mentioned. As said support film, the thing similar to the transparent base | substrate of an anisotropic scattering film can be used. Furthermore, although the said polarizing plate is normally arrange | positioned at both the observation surface side and back side of a liquid crystal cell, it may be arrange | positioned only at the observation surface side and may be arrange | positioned only at the back side. The polarizing plate preferably further includes a retardation film. Thereby, the viewing angle dependency such as chromaticity of the liquid crystal display device can also be improved.

The display mode of the liquid crystal display device is not particularly limited. For example, a VA (Vertical Alignment) mode, a TN (Twisted Nematic) mode, an IPS (In-Plane Switching) mode, or an OCB (Optically Compensated Birefringence) mode is preferable.

The VA mode is a method in which liquid crystal molecules are aligned substantially perpendicular to the substrate surface when no voltage is applied, and display is performed by tilting the liquid crystal molecules when a voltage is applied. Examples of the VA mode include an MVA (Multi-domain Vertical Alignment) mode in which a protrusion structure and / or a slit is provided on a substrate and a liquid crystal cell is divided into a plurality of domains. Note that in the VA mode liquid crystal display device, the liquid crystal preferably has negative dielectric anisotropy.

The TN mode is oriented so that the major axis of the liquid crystal molecules is substantially parallel to the substrate surface and twists continuously by a predetermined angle (twist angle) between a pair of substrates when no voltage is applied. In this method, the long axis is rearranged so as to be parallel to the electric field direction. Note that the TN mode includes not only a normal TN mode with a twist angle of 90 ° but also an STN mode with a twist angle of 180 ° or more. In the TN mode liquid crystal display device, the liquid crystal preferably has positive dielectric anisotropy.

The IPS mode is a method in which display is performed by rotating a liquid crystal within a substrate surface by a horizontal electric field applied to a pair of comb electrodes provided on one substrate. When the liquid crystal molecules have a negative dielectric anisotropy, the major axis of the liquid crystal molecules is arranged in a direction substantially perpendicular to the comb teeth direction of the comb electrode when no voltage is applied. It is rotated in a direction substantially parallel to the comb teeth direction. When the liquid crystal molecules have a positive dielectric anisotropy, the major axis of the liquid crystal molecules is arranged in a direction substantially parallel to the comb teeth direction of the comb electrode when no voltage is applied. It is rotated in a direction substantially perpendicular to the comb tooth direction. When no voltage is applied, the major axis of the liquid crystal molecules is arranged substantially parallel to the substrate surface and the polarization axis of one of the polarizing elements, regardless of whether the dielectric anisotropy of the liquid crystal molecules is positive or negative.
The OCB mode is a system that provides an optically complementary alignment structure (bend alignment) in the thickness direction of the liquid crystal and performs three-dimensional optical compensation using a retardation film.

According to the display device of the present invention, without changing the design of the basic structure of the display device, without being limited to the white display state or the black display state, at least a specific orientation without impairing the display quality in other directions. The viewing angle dependence of the contrast ratio can be improved.

1. Production of liquid crystal display device <Example 1>
(Preparation of first anisotropic scattering film)
First, a liquid resin is applied to the edge of a polyethylene terephthalate (PET) film having a thickness of 75 μm and a size of 76 × 26 mm (trade name: Cosmo Shine (registered trademark), product number: A4300, manufactured by Toyobo Co., Ltd.) using a dispenser. After discharging, the liquid resin was cured to form a partition wall having a height of 0.2 mm. Next, after dripping the photopolymerizable composition of the following composition in the area | region enclosed by the partition, it coat | covered with another PET film.

≪Composition of photopolymerizable composition≫
2- (perfluorooctyl) -ethyl acrylate 50 parts by weight 1,9-nonanediol diacrylate 50 parts by weight 2-hydroxy-2-methyl-1-phenylpropan-1-one 4 parts by weight

Next, from an irradiation unit for epi-illumination of a UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics) from a vertical direction with respect to a liquid film having a thickness of 0.2 mm sandwiched between upper and lower PET films. An ultraviolet ray having an irradiation intensity of 30 mW / cm ² was irradiated for 1 minute from an angle inclined by 30 ° to obtain a first anisotropic scattering film. In addition, when the cross section of the first anisotropic scattering film is observed with a microscope, the presence of the rod-shaped cured region 20 extending at an angle of 30 ° with respect to the normal direction of the film surface as shown in FIG. confirmed.

(Measurement of scattering characteristics of first anisotropic scattering film)
FIG. 6 is a schematic perspective view showing a method for measuring the anisotropic scattering characteristics of the first anisotropic scattering film.
According to the method shown in FIG. 6, by rotating the test piece 10a about a predetermined direction as a rotation axis, a straight line when the optical axis and the normal direction of the test surface coincide (when the incident angle is 0 °). Not only the transmitted light amount but also the linear transmitted light amount when the optical axis and the normal direction of the test surface do not match (when the incident angle is other than 0 °) can be measured. Specifically, first, using a goniophotometer (trade name: automatic goniophotometer GP-5, manufactured by Murakami Color Research Laboratory), as shown in FIG. 6, straight from a light source (not shown) The light receiving unit 30 was fixed at a position to receive light, and a first anisotropic scattering film was attached as a test piece 10 a to a sample holder (not shown) between the light source and the light receiving unit 30. Next, as shown in FIG. 6, the first anisotropic scattering film 10a is rotated with the short side direction of the first anisotropic scattering film 10a as the rotation axis (L) (hereinafter referred to as “short side axis rotation”). The linear transmitted light amount corresponding to each incident angle was measured. Next, the first anisotropic scattering film 10a is rotated (hereinafter also referred to as “long-side axis rotation”) with the long side direction of the first anisotropic scattering film 10a as the rotation axis (M). The amount of linear transmitted light corresponding to the incident angle was measured.

The short side axis direction of the first anisotropic scattering film 10a coincides with the direction perpendicular to the extending direction of the rod-like cured region 20, and the long side axis direction coincides with the extending direction of the rod-like cured region 20. To do. That is, the anisotropic scattering characteristics in the extending orientation of the rod-shaped cured region 20 are measured by rotating the first anisotropic scattering film 10a by the short side axis, and the rod-shaped cured region 20 of the rod-shaped cured region 20 is rotated by rotating the long side axis. The anisotropic scattering characteristics in the direction perpendicular to the extension direction were measured.

FIG. 7 is a diagram illustrating a relationship between an incident angle and a linear transmitted light amount when the first anisotropic scattering film is rotated around the two rotation axes. In addition, the positive / negative of an incident angle shows that the direction which rotates a 1st anisotropic scattering film is reverse.

From FIG. 7, it was found that the extending direction of the rod-shaped hardened region 20 has a deep valley shape including a small mountain at an incident angle of 30 °. Further, it was found that in the direction perpendicular to the extending direction of the rod-shaped hardened region 20, it is a valley shape in which the incident angle is 0 °. Therefore, it was found that the first anisotropic scattering film 10a has a scattering center axis in a direction coinciding with the extending direction of the rod-shaped cured region 20, that is, the polar angle of the scattering center axis is 30 °.

FIG. 8 is a schematic perspective view showing the configuration of the VA mode liquid crystal display device according to Embodiment 1 of the present invention. In addition, the bonding of each film and the relative relationship in the axial direction are as shown in FIG.

(Production of VA mode liquid crystal display device 15a)
First, the relationship between the birefringence Δn of the liquid crystal material and the cell thickness d is adjusted to Δnd = 300 nm, and the tilt direction of the liquid crystal molecules is divided into four directions of azimuth angles of 45 °, 135 °, 225 °, and 315 ° when a voltage is applied. A prototype VA mode liquid crystal cell 11a was prepared. Next, the first retardation film 12a is bonded to the backlight side of the VA mode liquid crystal cell 11a, and further on the backlight side of the first retardation film 12a and the observation surface side of the VA mode liquid crystal cell 11a. The VA mode liquid crystal display device 15a was obtained by laminating a first polarizing plate 13a whose supporting film on the VA mode liquid crystal cell 11a side was a TAC (triacetyl cellulose) film.

The retardation of the first retardation film 12a is Re = 3 nm and Rth = 250 nm. Of the three main refractive indexes of the refractive index ellipsoid, Re is nx, ny (nx ≧ ny), two main refractive indexes in the plane, nz is one main refractive index in the normal direction, and a retardation film Is defined by the following formula (1).
Re = (nx−ny) × d (1)

Rth is represented by the following formula (2) when nx, ny, nz, and d are defined as described above.
Rth = (nx−nz) × d (2)

The calculation method of Re and Rth is the same in the following examples and comparative examples. Moreover, the performance of the polarizing element constituting the first polarizing plate 13a is a parallel transmittance of 36.25%, an orthogonal transmittance of 0.005%, and a polarization degree of 99.99%.

(Measurement of optical characteristics of VA mode liquid crystal display device 15a)
The azimuth angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a produced in Example 1 was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). The result is shown in FIG. As can be seen from FIG. 17, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a is minimal is the azimuth angle Φ = 45 °, 135 °, 225 °, 315 There were 4 orientations.

(Production of VA mode liquid crystal display device 100a)
Then, as the axial direction S ₁ of the scattering center axis of the VA mode liquid crystal display azimuth [Phi = 45 ° of the orientation device 15a (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The 1st anisotropic scattering film 10a was bonded to the observation surface side of the display device 15a, and it was set as the VA mode liquid crystal display device 100a.

<Example 2>
FIG. 9 is a schematic perspective view showing the configuration of the VA mode liquid crystal display device 100a according to the second embodiment of the present invention. Note that the lamination of the films and the relative relationship in the axial direction are as shown in FIG.

(Production of VA mode liquid crystal display device 15a)
First, the second polarizing plate 13b in which the support film on the liquid crystal cell 11a side is the second retardation film 12b is bonded to the observation surface side of the VA mode liquid crystal cell 11a prototyped in Example 1, and the backlight side A VA mode liquid crystal display device 15a was obtained by laminating a third polarizing plate 13c whose supporting film on the liquid crystal cell 11a side was the third retardation film 12c.
The retardation of the second retardation film 12b is Re = 140 nm and Rth = 138 nm. The retardation of the third retardation film 12c is Re = 2 nm and Rth = 190 nm. Furthermore, the performance of the polarizing element 3a is the same as that of the polarizing element of Example 1.

(Measurement of optical characteristics of VA mode liquid crystal display device 15a)
The azimuth angle dependence of the contrast ratio in the polar angle Θ = 45 ° direction of the VA mode liquid crystal display device 15a produced in Example 2 was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). As in the first embodiment, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a is minimized is the azimuth angle Φ = 45 °, 135 °, 225 °, There were four directions at 315 °.

(Production of VA mode liquid crystal display device 100a)
Then, as the axial direction S ₁ of the scattering center axis of the VA mode liquid crystal display azimuth [Phi = 45 ° of the orientation device 15a (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The 1st anisotropic scattering film 10a was bonded to the observation surface side of the display device 15a, and it was set as the VA mode liquid crystal display device 100a.

<Example 3>
FIG. 10 is a schematic perspective view illustrating a configuration of a VA mode liquid crystal display device 100a according to the third embodiment of the present invention. Note that the lamination of the films and the relative relationship in the axial direction are as shown in FIG.

(Production of VA mode liquid crystal display device 15a)
First, the fourth retardation film 12d is bonded to the backlight side of the VA mode liquid crystal cell 11a prototyped in Example 1, and further the backlight side of the fourth retardation film 12d and the liquid crystal cell 11a. The first polarizing plate 13a whose supporting film on the liquid crystal cell 11a side is a TAC film is bonded to the observation surface side to obtain a VA mode liquid crystal display device 15a.
The retardation of the fourth retardation film 12d is Re = 50 nm and Rth = 220 nm. The performance of the first polarizing plate 13a is the same as that of the first embodiment.

(Measurement of optical characteristics of VA mode liquid crystal display device 15a)
The azimuth angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a produced in Example 3 was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). As in the first embodiment, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a is minimized is the azimuth angle Φ = 45 °, 135 °, 225 °, There were four directions at 315 °.

(Production of VA mode liquid crystal display device 100a)
Then, as the axial direction S ₁ of the scattering center axis of the VA mode liquid crystal display azimuth [Phi = 45 ° of the orientation device 15a (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The 1st anisotropic scattering film 10a was bonded to the observation surface side of the display device 15a, and it was set as the VA mode liquid crystal display device 100a.

<Example 4>
FIG. 11 is a schematic perspective view illustrating a configuration of a VA mode liquid crystal display device 100a according to the fourth embodiment of the present invention. In addition, bonding of each film and the relative relationship in the axial direction are as shown in FIG.

(Production of VA mode liquid crystal display device 15a)
First, the fifth polarizing plate 13e, in which the support film on the liquid crystal cell 11a side is the fifth retardation film 12e, is bonded to the observation surface side of the VA mode liquid crystal cell 11a prototyped in Example 1, and the backlight side A VA mode liquid crystal display device 15a was obtained by laminating a sixth polarizing plate 13f whose supporting film on the liquid crystal cell 11a side was the sixth retardation film 12f.
The fifth and sixth retardation films 12e and 12f both have Re = 60 nm and Rth = 90 nm. The performance of the polarizing element 3a is the same as that of the polarizing element of Example 1.

(Measurement of optical characteristics of VA mode liquid crystal display device 15a)
The azimuth angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a produced in Example 4 was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). As in the first embodiment, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a is minimized is the azimuth angle Φ = 45 °, 135 °, 225 °, There were four directions at 315 °.

(Production of VA mode liquid crystal display device 100a)
Then, as the axial direction S ₁ of the scattering center axis of the VA mode liquid crystal display azimuth [Phi = 45 ° of the orientation device 15a (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The 1st anisotropic scattering film 10a was bonded to the observation surface side of the display device 15a, and it was set as the VA mode liquid crystal display device 100a.

<Example 5>
FIG. 12 is a schematic perspective view illustrating a configuration of a VA mode liquid crystal display device 100a according to the fifth embodiment of the present invention. In addition, bonding of each film and the relative relationship in the axial direction are as shown in FIG.

(Production of VA mode liquid crystal display device 15a)
First, the seventh polarizing plate 13g, in which the support film on the liquid crystal cell 11a side is the seventh retardation film 12g, is bonded to the observation surface side of the VA mode liquid crystal cell 11a prototyped in Example 1, and the backlight side The VA mode liquid crystal display device 15a was obtained by laminating an eighth polarizing plate 13h whose supporting film on the liquid crystal cell 11a side was the eighth retardation film 12h.
The retardation of the seventh retardation film 12g is Re = 90 nm and Rth = 100 nm, and the retardation of the eighth retardation film 12h is Re = 3 nm and Rth = 100 nm. The performance of the polarizing element 3a is the same as that of the polarizing element of Example 1.

(Measurement of optical characteristics of VA mode liquid crystal display device 15a)
The azimuth angle dependence of the contrast ratio in the direction of polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a produced in Example 5 was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). As in the first embodiment, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the VA mode liquid crystal display device 15a is minimized is the azimuth angle Φ = 45 °, 135 °, 225 °, There were four directions at 315 °.

(Production of VA mode liquid crystal display device 100a)
Then, as the axial direction S ₁ of the scattering center axis of the VA mode liquid crystal display azimuth [Phi = 45 ° of the orientation device 15a (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The 1st anisotropic scattering film 10a was bonded to the observation surface side of the display device 15a, and it was set as the VA mode liquid crystal display device 100a.

<Example 6>
FIG. 13 is a schematic perspective view illustrating a configuration of a TN mode liquid crystal display device 100b according to the sixth embodiment of the present invention. In addition, bonding of each film and the relative relationship in the axial direction are as shown in FIG.

(Preparation of TN mode liquid crystal display device 15b)
First, a TN mode liquid crystal cell 11b in which the relationship between the birefringence Δn of the liquid crystal material and the cell thickness d is adjusted to Δnd = 350 nm is prototyped, and a polarizing plate with a wide view (WV) film 4 (trade name: Product name: A polarizing plate with viewing angle compensation film NWF-KD • EG, manufactured by Nitto Denko Corporation) 13i was bonded to obtain a TN mode liquid crystal display device 15b.
The polarizing element 3b is different from the polarizing element 3a. The performance of the polarizing plate 13i was a parallel transmittance of 36.10%, an orthogonal transmittance of 0.005%, and a polarization degree of 99.99%.

(Measurement of optical characteristics of TN mode liquid crystal display device 15b)
The azimuth angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 ° of the TN mode liquid crystal display device 15b was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). The result is shown in FIG. As can be seen from FIG. 18, the azimuth (minimum azimuth) at which the contrast ratio in the direction of the polar angle Θ = 45 ° of the TN mode liquid crystal display device 15b is minimal is the azimuth angle Φ = 0 °, 90 °, 180 °, 270. There were 4 orientations.

(Preparation of TN mode liquid crystal display device 100b)
Then, as the axial direction S ₁ of the scattering center axis of the TN mode liquid crystal display azimuth [Phi = 270 ° of the orientation of device 15b (the minimum azimuth) first anisotropic scattering film 10a substantially coincide, the liquid crystal The first anisotropic scattering film 10a was bonded to the observation surface side of the display device 15b to obtain a TN mode liquid crystal display device 100b.

<Example 7>
(Preparation of second anisotropic scattering film)
The first anisotropic scattering film except that UV irradiation with an irradiation intensity of 30 mW / cm ² was irradiated vertically from an irradiation unit for incident light of a UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics) for 1 minute. It is the same as the manufacturing method. This obtained the 2nd anisotropic scattering film. In addition, when the cross section of the second anisotropic scattering film was observed with a microscope, the presence of the rod-shaped cured region 20 extending in the normal direction of the film surface as shown in FIG. 2C was confirmed.

(Measurement of scattering characteristics of second anisotropic scattering film)
FIG. 5 is a diagram showing a relationship between an incident angle and a linear transmitted light amount when the second anisotropic scattering film is rotated around two rotation axes (long side axis and short side axis) orthogonal to each other. It is. In addition, the solid line in a figure shows the case where it rotates with a short side axis, and the broken line shows the case where it rotates with a long side axis. Further, the positive / negative of the incident angle indicates that the rotating direction is opposite.
The scattering characteristics of the second anisotropic scattering film were measured in the same manner as the first anisotropic scattering film. From FIG. 5, both the case where the short side axis was rotated and the case where the long side axis was rotated were used. It was found that the second anisotropic scattering film has a deep valley shape including a small peak at an incident angle of 0 °, and exhibits substantially left-right symmetric anisotropic scattering characteristics. Moreover, it turned out that the 2nd anisotropic scattering film shows the substantially the same anisotropic scattering characteristic by the case where it rotates the short side axis and the case where it rotates the long side axis. Furthermore, this showed that the second anisotropic scattering film had a scattering center axis in the normal direction of the film surface. Note that the rate of change in the amount of linear transmitted light was 0.90 both when the short side axis was rotated and when the long side axis was rotated.

(Preparation of TN mode liquid crystal display device 200b)
FIG. 14 is a schematic perspective view showing a configuration of a TN mode liquid crystal display device 200b according to Example 7 of the present invention. In addition, the bonding of each film and the relative relationship in the axial direction are as shown in FIG.
Example 6 is the same as Example 6 except that the second anisotropic scattering film 10b is bonded to the observation surface side of the TN mode liquid crystal display device 15b instead of the first anisotropic scattering film 10a. The second anisotropic scattering film 10b, in order to have a scattering central axis in the normal direction of the film surface is considered to have an axis direction S ₁ of the scattering central axis in all directions.

<Example 8>
FIG. 15 is a schematic perspective view illustrating a configuration of an IPS mode liquid crystal display device 100c according to an eighth embodiment of the present invention. Note that the lamination of the films and the relative relationship in the axial direction are as shown in FIG.

(Preparation of IPS mode liquid crystal display device 15c)
First, the polarizing plate bonded to the observation surface side and the backlight side of a commercially available IPS mode liquid crystal TV (trade name: TH-26LX50, manufactured by Matsushita Electric Industrial Co., Ltd.) was peeled off to prepare an IPS mode liquid crystal cell 11c. Next, the ninth retardation film 12j is bonded to the backlight side of the liquid crystal cell 11c, and the ninth polarization film is further applied to the backlight side of the ninth retardation film 12j and the observation surface side of the liquid crystal cell 11c. The plate 13j was bonded to obtain an IPS mode liquid crystal display device 15c.
The retardation of the ninth retardation film 12j is Re = 140 nm and Rth = 45 nm. Furthermore, the performance of the ninth polarizing plate 13j was a parallel transmittance of 35.95%, an orthogonal transmittance of 0.004%, and a polarization degree of 99.99%.

(Measurement of optical characteristics of IPS mode liquid crystal display device 15c)
The azimuth angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 ° of the IPS mode liquid crystal display device 15c was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). The result is shown in FIG. As can be seen from FIG. 19, the azimuth (minimum azimuth) in which the contrast ratio in the direction of the polar angle Θ = 45 ° of the IPS mode liquid crystal display device 15c is minimal is the azimuth angle Φ = 45 °, 135 °, 225 °, 315 There were 4 orientations.

(Preparation of IPS mode liquid crystal display device 100c)
Then, as the axial direction S ₁ of IPS mode liquid crystal display device 15c azimuth [Phi = 45 ° orientation of the (minimum azimuth) scattering central axis of the first anisotropic scattering film 10a substantially coincide, the liquid crystal The first anisotropic scattering film 10a was bonded to the observation surface side of the display device 15c to obtain an IPS mode liquid crystal display device 100c.

<Example 9>
(Production of OCB mode liquid crystal display device and measurement of optical properties)
A part of the polarizing plate on the backlight side of a commercially available OCB mode liquid crystal TV (trade name: VT23XD1, manufactured by Nanao Co., Ltd.) was peeled off and bonded to the observation surface side to obtain an OCB mode liquid crystal display device. In addition, the performance of the partially peeled polarizing plate was a parallel transmittance of 36.30%, an orthogonal transmittance of 0.005%, and a polarization degree of 99.99%. Next, the azimuth angle dependency of the contrast ratio in the polar angle Θ = 45 ° direction of the OCB mode liquid crystal display device was measured using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM). The result is shown in FIG. As can be seen from FIG. 20, the azimuth (minimum azimuth) in which the contrast ratio in the direction of the polar angle Θ = 45 ° of the OCB mode liquid crystal display device 15c is minimal is the azimuth angle Φ = 0 °, 90 °, 180 °, 270 There were 4 orientations.

(Preparation of OCB mode liquid crystal display device)
Then, as the axial direction S ₁ of OCB mode liquid crystal display device of the azimuth angle [Phi = 0 ° orientation (the minimum azimuth) scattering central axis of the first anisotropic scattering film 10a substantially coincide, OCB mode The first anisotropic scattering film 10a was bonded to the surface on the observation surface side of the liquid crystal display device to obtain an OCB mode liquid crystal display device.

<Comparative Example 1>
(Preparation of isotropic scattering film)
On one side of a 75 μm thick PET film (trade name: Cosmo Shine (registered trademark), product number: A4300, manufactured by Toyobo Co., Ltd.), a UV paint having the following formulation was applied with a wire bar. Next, the film coated with the UV paint was dried and irradiated with UV (cured) to obtain an isotropic scattering film having a coating layer having a thickness of about 3 μm.

≪UV paint≫
UV curable resin (trade name: Beam Set (registered trademark) 575CB, nonvolatile content 100%, manufactured by Arakawa Chemical Industries, Ltd.) 98 parts by weight polystyrene fine particles (trade name: SX350H, average particle size: 3.5 μm, Soken Chemical Co., Ltd.) Made) 12 parts by weight MIBK (methyl isobutyl ketone) 100 parts by weight

(Measurement of scattering characteristics of isotropic scattering film)
About the measuring method, it is the same as that of a 1st anisotropic scattering film. The scattering characteristics of the isotropic scattering film are shown in FIG. In the case of an isotropic scattering film, as shown in FIG. 16, the graph showing the incident angle dependence of the scattering characteristics has a convex shape centered on the incident angle of 0 °. This is because the distance through the film increases as the incident angle increases.
The sign of the incident angle indicates that the direction of rotation is opposite.

(Production of liquid crystal display device)
On the observation surface side of the VA mode liquid crystal display device 15a prototyped in Example 1, the turbidity measured with a turbidimeter (trade name: NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.) is 30%. A VA mode liquid crystal display device was obtained by laminating the ionic scattering film. In addition, it is the same as Example 1 except having used the isotropic scattering film instead of the 1st anisotropic scattering film.

<Comparative example 2>
(Production of liquid crystal display device)
A viewing angle control film (product name: Lumisty (registered trademark), product number: MFY-1060, manufactured by Sumitomo Chemical Co., Ltd.) is bonded to the observation surface side of the VA mode liquid crystal display device 15a prototyped in Example 3, and VA mode liquid crystal is attached. A display device was obtained. Lumisty (registered trademark) is a film that exhibits anisotropic scattering characteristics in a specific direction. In this comparative example, Lumisty (registered trademark) that scatters light incident at a polar angle Θ = 10 to 60 ° in a certain direction (hereinafter also referred to as “scattering direction”) is used, and the scattering direction is a VA mode liquid crystal display device. It was bonded to the observation surface side of the VA mode liquid crystal display device 15a so as to substantially coincide with the azimuth (minimum azimuth) of 15a azimuth angle Φ = 45 °. Therefore, the configuration of this comparative example is the same as that of Example 3 except that Lumisty (registered trademark) is used instead of the first anisotropic scattering film.

2. Measurement of optical characteristics of liquid crystal display device For the liquid crystal display devices of Examples 1 to 9 and Comparative Examples 1 and 2, using a viewing angle measurement device (trade name: EZContrast 160R, manufactured by ELDIM), 256 gradation display is performed. The viewing angle dependence of luminance and chromaticity during black display (gradation value: 0), halftone display (gradation value: 128), and white display (gradation value: 255) was measured. The viewing angle is represented by a polar angle Θ and an azimuth angle Φ.

<Evaluation of improvement in contrast ratio>
For each liquid crystal display device, the polar angle dependence of the contrast ratio in the orientation (minimum orientation) in which the contrast ratio in the direction of the polar angle Θ = 45 ° of the liquid crystal display device is minimized was evaluated. That is, in the VA mode and IPS mode liquid crystal display devices, the four azimuth angles Φ = 45 °, 135 °, 225 °, and 315 °, and in the TN mode and OCB mode liquid crystal display devices, the azimuth angle Φ = 0 °, The polar angle dependence of the contrast ratio in four directions of 90 °, 180 °, and 270 ° was evaluated.
The contrast ratio was obtained from the measured luminance during black display (tone value: 0) and white display (tone value: 255) using the following equation (3).
(Contrast ratio) = (White display brightness) / (Black display brightness) (3)

FIGS. 21A to 21B show the polar angle dependency of the contrast ratio in the minimum direction of the liquid crystal display devices and liquid crystal display devices according to Examples 1 to 9 and Comparative Examples 1 and 2. FIG. The solid line in each figure indicates the polar angle dependency of the contrast ratio of the liquid crystal display device, and the broken line indicates the polar angle dependency of the contrast ratio of the liquid crystal display device.

(A) in FIGS. 21 to 31 is the polar angle of the contrast ratio in two minimal directions substantially parallel to the axial direction of the scattering center axis of the first anisotropic scattering film 10a or the second anisotropic scattering film 10b. (B) shows the polar angle dependence of the contrast ratio in two directions perpendicular to the minimum direction.
In the VA mode liquid crystal display devices according to Examples 1 to 5 of the present invention, as is clear from FIGS. 21 to 25A, the minimum azimuth (azimuth angle Φ = 45 °) substantially coincides with the axial direction of the scattering center axis. )), The contrast ratio is improved in the vicinity of the axial direction of the scattering center axis (polar angle Θ = 30 ° direction), and the effect of improving the viewing angle dependency of the contrast ratio is obtained. Further, in the azimuth opposite to the minimal azimuth (azimuth of azimuth angle Φ = 225 °) and two azimuths perpendicular to the minimal azimuth (azimuth angle Φ = 135, azimuth of 270 °), FIGS. As is clear from (a) and (b), there was no influence such as a decrease in contrast ratio.

However, in the VA mode liquid crystal display device according to Comparative Example 1, as shown in FIGS. 30 (a) and 30 (b), the contrast ratio was not improved in any orientation. In addition, in the VA mode liquid crystal display device according to Comparative Example 2, as shown in FIG. 31A, the viewing angle was improved in the minimum azimuth (azimuth Φ = 45 ° azimuth) substantially coincident with the scattering direction. However, as shown in FIG. 31 (b), the contrast ratio is extremely lowered in two directions almost perpendicular to the scattering direction (azimuth Φ = 135, 270 ° azimuth), and the front direction ( The maximum contrast ratio obtained at the polar angle Θ = 0 ° was also extremely reduced.

Further, in the TN mode liquid crystal display device according to Example 6 of the present invention, as is apparent from FIG. 26A, the minimum azimuth (azimuth of Φ = 270 °) substantially coincides with the axial direction of the scattering center axis. The contrast ratio was improved in the vicinity of the axial direction of the scattering center axis (polar angle Θ = 30 ° direction), and the effect of improving the viewing angle dependency of the contrast ratio was obtained. Also, in the azimuth opposite to the minimum azimuth (azimuth of azimuth angle Φ = 90 °) and two azimuths perpendicular to the minimum azimuth (azimuth angle Φ = 0, azimuth of 180 °), FIG. As is clear from (b), there was no influence such as a decrease in contrast ratio.

Furthermore, in the TN mode liquid crystal display device according to Example 7 of the present invention, as is apparent from FIGS. 27A and 27B, the tilt is 10 ° from the normal direction of the observation surface to the azimuth of azimuth 180 °. The viewing angle dependence of the contrast ratio in the four minimum directions (azimuth angles Φ = 0, 90, 180, 270 °) was improved without substantially reducing the maximum contrast ratio obtained in the selected direction.

Then, in the IPS mode liquid crystal display device according to Example 8 of the present invention, as is apparent from FIG. 28A, the minimum azimuth (azimuth of azimuth angle Φ = 45 °) substantially coincides with the axis direction of the scattering center axis. The contrast ratio was improved in the vicinity of the axial direction of the scattering center axis (polar angle Θ = 30 ° direction), and the effect of improving the viewing angle dependency of the contrast ratio was obtained. Also, in the azimuth opposite to the minimum azimuth (azimuth of azimuth angle Φ = 225 °) and two azimuths perpendicular to the minimum azimuth (azimuth angle Φ = 135, 315 ° azimuth), FIG. As is clear from (b), there was no influence such as a decrease in contrast ratio.

Then, in the OCB mode liquid crystal display device according to Example 9 of the present invention, as is clear from FIG. 29A, the minimum azimuth (azimuth of azimuth angle Φ = 0 °) substantially coincides with the axial direction of the scattering center axis. The contrast ratio was improved in the vicinity of the axial direction of the scattering center axis (polar angle Θ = 30 ° direction), and the effect of improving the viewing angle dependency of the contrast ratio was obtained. Also, in the azimuth opposite to the minimum azimuth (azimuth of azimuth angle Φ = 180 °) and two directions perpendicular to the minimum azimuth (azimuth angle Φ = 90, 270 ° azimuth), FIG. As is clear from (b), there was no influence such as a decrease in contrast ratio.

This is explained as follows. According to the liquid crystal display devices according to Examples 1 to 9 of the present invention, the first anisotropic scattering film or the second anisotropic scattering film has an axis direction of the scattering center axis of the observation surface of the liquid crystal display device. Pasted on the observation surface side of the liquid crystal display device so that the contrast ratio in a direction inclined by 45 ° from the normal direction is substantially the same as the minimum orientation (minimum orientation), and is approximately in the axial direction of the scattering central axis. Since parallel incident light (black luminance) can be averaged by being scattered (diffused) in all directions around the scattering center axis, it can be contrasted at least in the minimal direction that almost matches the axis direction of the scattering center axis. The viewing angle dependency of the ratio can be improved. In addition, the first anisotropic scattering film exhibits scattering characteristics as shown in FIG. 7, and the second anisotropic scattering film exhibits scattering characteristics as shown in FIG. Since light incident from a direction other than a direction substantially parallel to the light is scattered only weakly, it is possible to suppress deterioration of display quality in a direction with a large contrast ratio due to scattering of light incident from the same direction.

On the other hand, according to the liquid crystal display device according to Comparative Example 1, the isotropic scattering film used instead of the first anisotropic scattering film or the second anisotropic scattering film is as shown in FIG. In this case, the incident light in a specific direction cannot be scattered and averaged in all directions, so that the viewing angle dependency of the contrast ratio cannot be improved. Further, according to the liquid crystal display device according to Comparative Example 3, Lumisty (registered trademark) used in place of the first anisotropic scattering film or the second anisotropic scattering film is different only in a specific orientation. Because it does not show the side scatter characteristic, in the direction that does not show the anisotropic scatter characteristic, even the incident light in the direction with a small contrast ratio is strongly scattered. As a result, it can be obtained in the front direction by scattering of the incident light in the same direction. The maximum contrast ratio is lowered.

<Evaluation of gamma curve shift improvement>
Gamma curve in the front direction (polar angle Θ = 0 ° direction) and diagonal direction (polar angle Θ = 40 °, orientation is the minimum angle ratio of each liquid crystal display device in the direction of polar angle Θ = 40 °) Gamma curve in the direction that is the direction), normalize the brightness in each gradation display so that the white display brightness is 1, and normalize the front direction in halftone display (gradation value: 128) The difference (deviation amount) between the luminance and the normalized luminance in each oblique direction was calculated. Table 9 shows the ratio of the improvement effect from the liquid crystal display device. That is, the larger the numerical value described in the table, the greater the improvement effect.

As is clear from Table 9, in the liquid crystal display devices according to Examples 1 to 5 of the present invention, the gamma curve of the minimum azimuth (azimuth of azimuth angle Φ = 45 °) substantially coincides with the axial direction of the scattering center axis. The effect of improving the deviation was greatly obtained. In addition, the effect of improving the deviation of the gamma curve was also obtained in three minimal orientations (azimuth angles Φ = 135 °, 225 °, 315 °) other than the minimal orientation. However, in the liquid crystal display device according to Comparative Example 1, the effect of improving the deviation of the gamma curve was small in any minimum direction. Further, in the liquid crystal display device according to the comparative example 2, although the effect of improving the deviation of the gamma curve was obtained in the minimum azimuth (azimuth of azimuth angle Φ = 45 °) substantially coincident with the scattering direction, the viewing angle of the above-described contrast ratio was obtained. As shown in the evaluation results of the dependency improvement, the maximum contrast ratio was greatly reduced.

This is explained as follows. The gamma curve of the VA mode liquid crystal display device is normally optimally designed in the direction in which the contrast ratio is maximized, and the viewing angle dependency thereof shows the same tendency as the viewing angle dependency of the contrast ratio. According to the liquid crystal display devices according to Examples 1 to 5 and Comparative Example 2 of the present invention, the first anisotropic scattering film and Lumisty (registered trademark) exhibit anisotropic scattering characteristics in at least one orientation. When each film is bonded to the observation surface side of the VA mode liquid crystal display device, the orientation indicating the anisotropic scattering characteristics of each film and the minimal orientation of the VA mode liquid crystal display device are substantially matched to each other in the minimal orientation. The viewing angle dependence of the gamma curve can be greatly improved. In addition, according to the liquid crystal display device which concerns on Examples 1-5 of this invention, since the 1st anisotropic scattering film shows anisotropic scattering characteristics in all the directions, the direction which shows the anisotropic scattering characteristics of each film The viewing angle dependence of the gamma curve can also be improved in three minimum directions other than the minimum direction almost coincident with. On the other hand, according to the liquid crystal display device according to Comparative Example 1, since the isotropic scattering film used in place of the first anisotropic scattering film does not exhibit anisotropic scattering characteristics, it is incident in a specific direction. It is impossible to scatter and average only light in all directions, and as a result, the viewing angle dependence of the gamma curve cannot be improved.

(A) is a schematic diagram explaining the direction of polar angle (theta) of a display device. (B) is a schematic diagram explaining the azimuth | direction of a display device. (C) is a schematic diagram explaining the azimuth angle dependency of the contrast ratio in the direction of the polar angle Θ (constant) of the display device. (A) is a perspective schematic diagram which shows an example of the structure of the anisotropic scattering film (anisotropic scattering layer) which comprises the display apparatus of this invention. (B) is a figure explaining the polar angle and axial orientation of the scattering center axis | shaft of an anisotropic scattering film. (C) is a perspective schematic diagram which shows an example of the structure of the anisotropic scattering film (anisotropic scattering layer) which comprises the display apparatus of this invention. It is a graph which shows the azimuth | direction dependence of the contrast ratio in the direction whose polar angle of the liquid crystal display device of VA mode is 10 degrees, 20 degrees, and 45 degrees. It is explanatory drawing which shows the relationship between the axial azimuth | direction of the scattering center axis | shaft of the anisotropic scattering film which comprises the display apparatus of this invention, and the minimum azimuth | direction of a display device. It is a figure which shows an example of the incident angle dependence of the scattering characteristic of the anisotropic scattering film which comprises the display apparatus of this invention. In addition, the solid line and the broken line in the figure indicate the incident angle dependence of the scattering characteristics when rotated about two rotation axes (short side axis and long side axis) orthogonal to each other. It is a perspective schematic diagram which shows the measuring method of the scattering characteristic of a scattering film. It is a figure which shows the incident angle dependence of the scattering characteristic of a 1st anisotropic scattering film. It is a perspective schematic diagram which shows the structure of the VA mode liquid crystal display device which concerns on Example 1 of this invention. It is a perspective schematic diagram which shows the structure of the VA mode liquid crystal display device which concerns on Example 2 of this invention. It is a perspective schematic diagram which shows the structure of the VA mode liquid crystal display device which concerns on Example 3 of this invention. It is a perspective schematic diagram which shows the structure of the VA mode liquid crystal display device which concerns on Example 4 of this invention. It is a perspective schematic diagram which shows the structure of the VA mode liquid crystal display device which concerns on Example 5 of this invention. It is a perspective schematic diagram which shows the structure of the TN mode liquid crystal display device which concerns on Example 6 of this invention. It is a perspective schematic diagram which shows the structure of the TN mode liquid crystal display device which concerns on Example 7 of this invention. It is a perspective schematic diagram which shows the structure of the IPS mode liquid crystal display device which concerns on Example 8 of this invention. It is a figure which shows the incident angle dependence of the scattering characteristic of an isotropic scattering film. It is a figure which shows the azimuth | direction dependence of the contrast ratio in the polar angle (theta) = 45 degree direction of the VA mode liquid crystal display device produced in Example 1 of this invention. It is a figure which shows the azimuth angle dependence of the contrast ratio in the polar angle (theta) = 45 degree direction of the TN mode liquid crystal display device produced in Example 6 of this invention. It is a figure which shows the azimuth angle dependence of the contrast ratio in the polar angle (theta) = 45 degree direction of the IPS mode liquid crystal display device produced in Example 8 of this invention. It is a figure which shows the azimuth angle dependence of the contrast ratio in the polar angle (theta) = 45 degree direction of the OCB mode liquid crystal display device produced in Example 9 of this invention. (A) is the polar angle dependence of the contrast ratio in two azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to the first embodiment of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is the polar angle dependence of the contrast ratio in the two azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Embodiment 2 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is the polar angle dependence of the contrast ratio in the two azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 3 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is the polar angle dependence of the contrast ratio in two azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 4 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is the polar angle dependence of the contrast ratio in the two azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 5 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is polar angle dependence of contrast ratio in two directions of azimuth angle Φ = 90 ° and 270 ° of TN mode liquid crystal display device (broken line) and liquid crystal display device (solid line) according to Example 6 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two azimuth angles of azimuth angle Φ = 0 ° and 180 °. (A) is polar angle dependence of the contrast ratio in two directions of azimuth angles Φ = 90 ° and 270 ° of the TN mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 7 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two azimuth angles of azimuth angle Φ = 0 ° and 180 °. (A) is the polar angle dependence of the contrast ratio in the two azimuth angles Φ = 45 ° and 225 ° of the IPS mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 8 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is the polar angle dependence of the contrast ratio in the two azimuth angles Φ = 90 ° and 270 ° of the OCB mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Example 9 of the present invention. It is a figure which shows sex. (B) is a diagram showing the polar angle dependence of the contrast ratio in two azimuth angles of azimuth angle Φ = 0 ° and 180 °. (A) shows the polar angle dependence of the contrast ratio in two directions of azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Comparative Example 1. FIG. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) shows the polar angle dependence of the contrast ratio in two directions of azimuth angles Φ = 45 ° and 225 ° of the VA mode liquid crystal display device (broken line) and the liquid crystal display device (solid line) according to Comparative Example 2. FIG. (B) is a diagram showing the polar angle dependence of the contrast ratio in two directions of azimuth angle Φ = 135 ° and 315 °. (A) is a perspective schematic diagram which shows an example of the scattering characteristic of the anisotropic scattering film which comprises the display apparatus of this invention. In the figure, P indicates the direction of the incident angle 0 °, S indicates the scattering center axis, and P (S) indicates that the direction of the incident angle 0 ° and the axial direction of the scattering center axis coincide with each other. Show. The length of the arrow extending from the intersection of the scattering center axis and the anisotropic scattering film to the bell-shaped curved surface (broken line in the figure) indicates the linear transmitted light amount in each direction. (B) is a plane schematic diagram when the bell-shaped curved surface which prescribes | regulates the linear transmitted light amount in (a) is seen from the front. It is a perspective schematic diagram which shows the structure of the conventional anisotropic scattering film. It is a schematic diagram which shows the scattering characteristic of the conventional anisotropic scattering film.

Explanation of symbols

3: Polarizer films 3a, 3b: Polarizing element 4: WV film 10: Anisotropic scattering layer 10a: First anisotropic scattering film 10b: Second anisotropic scattering film 11a: VA mode liquid crystal cell 11b: TN mode liquid crystal cell 11c: IPS mode liquid crystal cell 12a: first retardation film 12b: second retardation film 12c: third retardation film 12d: fourth retardation film 12e: fifth retardation film 12f: 6th phase difference film 12g: 7th phase difference film 12h: 8th phase difference film 12j: 9th phase difference film 13a: 1st polarizing plate 13b: 2nd polarizing plate 13c: 3rd Polarizing plate 13e: fifth polarizing plate 13f: sixth polarizing plate 13g: seventh polarizing plate 13h: eighth polarizing plate 13i: polarizing plate with WV film 13j: ninth polarizing plate 15: display Vice 15a: VA mode liquid crystal display device 15b: TN mode liquid crystal display device 15c: IPS mode liquid crystal display device 20: peripheral region a refractive index different areas (the rod-shaped curing zone)
30: light receiving unit 40: plate-like region having a refractive index different from the peripheral region 50: light control plate 51: linear light source 100: display device 100a: VA mode liquid crystal display device 100b, 200b: TN mode liquid crystal display device 100c: IPS Mode liquid crystal display device a: Absorption axis A: Angle formed between the minimum orientation M _I1 of the display device and the orientation of the azimuth angle 0 ° of the display device b: Orientation control direction C of the discotic liquid crystal in the WV film C: Isometric line d: orientation control direction of liquid crystal in the liquid crystal cell D: direction tilted Θ from the normal direction of the viewing surface of the display device M _I1 : minimal orientation s of the display device s: slow axis S: scattering center axis S _1: axis orientation of the scattering central axis S [delta]: angle between the axis orientation S ₁ of the scattering center axis a minimum azimuth M _I1 of the display device [Phi: azimuth omega: polar angle of the scattering central axis S

Claims (15)

A display device comprising a display device having a viewing angle dependency of a contrast ratio, and an anisotropic scattering film having an anisotropic scattering layer,
The anisotropic scattering film has a scattering center axis in an orientation substantially coincident with an orientation in which a contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device, and the display device is observed. A display device arranged on a surface side. The display device according to claim 1, wherein the scattering center axis substantially coincides with a normal direction of an observation surface of the display device. 2. The scattering central axis is inclined in an azimuth substantially coincident with an azimuth at which a contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device. Display device. The anisotropic scattering film has a scattering center axis in an orientation substantially coincident with an orientation in which a contrast ratio in a direction inclined at a constant angle of 20 ° or more from a normal direction of a viewing surface of the display device is minimized. The display device according to claim 1, characterized in that: The anisotropic scattering film has a scattering center axis in an orientation substantially coincident with an orientation in which a contrast ratio in a direction inclined by 45 ° from a normal direction of an observation surface of a display device is minimized. The display device according to 1. The display device according to claim 1, wherein the anisotropic scattering layer is formed by curing a composition containing a photocurable compound. The anisotropic scattering film has a direction in which the linear transmitted light amount is equal to or less than the linear transmitted light amount in the axial direction of the scattering central axis,
The azimuth in a direction that is less than or equal to the linearly transmitted light amount coincides with an azimuth in which a contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device. Display device. The axis direction of the scattering central axis is 15 ° or less with respect to the direction in which the contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device. Item 8. The display device according to Item 7. The axis direction of the scattering central axis is 10 ° or less with respect to an angle at which a contrast ratio is minimized in a direction inclined by a certain angle from the normal direction of the observation surface of the display device. Item 9. The display device according to Item 8. In the anisotropic scattering film, the angle formed between the direction in which the linear transmitted light amount is minimum and the axial direction of the scattering central axis is greater than the angle formed in the direction where the linear transmitted light amount is maximum and the axial direction of the scattering central axis. The display device according to claim 1, which is small. 2. The anisotropic scattering film according to claim 1, wherein a polar angle in a direction in which the linear transmitted light amount is minimum is smaller than a polar angle in a direction in which the linear transmitted light amount is maximum in any one direction. Display device. The anisotropic scattering film has an axial orientation of the scattering center axis, and the maximum linear transmission light amount in the direction where the polar angle is larger than the scattering center axis is the linear transmission light amount in the direction where the polar angle is smaller than the scattering center axis. The display device according to claim 1, wherein the display device is smaller than a maximum value. The display device according to claim 1, wherein the display device is a liquid crystal display device. The liquid crystal display device includes a liquid crystal cell in which liquid crystal is sandwiched between a pair of substrates,
The display device according to claim 13, further comprising a polarizing plate including a support film and a polarizing element. 14. The display device according to claim 13, wherein the display mode of the liquid crystal display device is a VA mode, a TN mode, an IPS mode, or an OCB mode.

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