JP2003207610A - Light diffusion body and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of yellow coloring of display light (diffusion light) and of lowering of diffusibility with respect to light incident from lateral directions inherent in a light diffusion body with anisotropy of diffusibility of emitted light varying corresponding to an incident angle of incident light in optical films (sheets) utilized to control a viewing angle of various display devices. <P>SOLUTION: The light diffusion body which has a projecting and recessing structure functioning so as to diffuse the emitted light independent of the incident angle of the incident light formed on at least one surface of the light diffusion body is adopted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffuser and a display device using the light diffuser, and more specifically, it is possible to realize a bright display screen without diffused light having a yellowish tint. The present invention relates to a light diffuser that can be used and a display device to which the light diffuser is applied. A liquid crystal display device (reflective type / transmissive type) is typical as a display device to which a light diffuser for controlling the viewing area of a display image is applied, but the present invention is not limited thereto, and a self-luminous type is used. It can also be applied to a display device having an image display element. Hereinafter, the case of a reflective liquid crystal display device will be mainly described.

[0002]

2. Description of the Related Art Conventionally, in a reflective liquid crystal display device,
In order to realize a wide viewing area, a light diffuser is used on the surface of a liquid crystal panel which is an image display element (Japanese Patent Laid-Open No. 11-2).
37502 publication). Generally, these light diffusers are isotropic ones that diffuse light incident in any direction in the same manner, and therefore, when reproducing the liquid crystal display device, the light is diffused twice when light is incident and when light is emitted. Since the light is diffused over the entire area, blurring of the image and deterioration of the contrast are conspicuous problems in visualizing a high-definition display image.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 11-352470, on the viewing side of a liquid crystal display device, a light diffuser is referred to as a front diffuser to diffuse light only for incident light within a specific range of incident angle. A technique using a light diffuser having characteristics (anisotropy = incidence angle selectivity) such that light is generated and emitted, and light incident at other incident angles is not diffused but simply transmitted is proposed. ing. By using such an anisotropic diffuser, light diffusion occurs only when light is incident, and does not occur when light is emitted after a high-definition display image pattern is defined on the liquid crystal panel. Therefore, it is possible to prevent the occurrence of blurring and the decrease in contrast due to the front diffuser.

[0004]

However, the light diffuser and the liquid crystal display device to which the light diffuser is applied have the following problems. An anisotropic light diffuser mainly diffuses light by diffraction scattering or Rayleigh scattering,
Diffused light is often colored yellow, and there is a problem that the diffusivity with respect to incident light from the lateral direction becomes small. The cause of the yellow tint is that the light of the blue component (short wavelength) is largely scattered, and the light of the yellow component having a complementary color relationship reaches the observer with little scattering. Therefore, the liquid crystal display device using the anisotropic light diffuser also has a problem that it becomes yellowish and the image becomes dark.

The present invention has been made in view of such circumstances, and the light diffusion characteristics are improved by providing the surface of the light diffuser having anisotropy or the vicinity thereof with an uneven structure which causes isotropic diffusion. An object of the present invention is to provide a light diffuser capable of realizing a bright display screen without being yellowed by adjusting and a display device to which the light diffuser is applied. In the present specification, diffusion and scattering, and diffuser and diffusion plate may be used as synonymous terms.

[0006]

According to a first aspect of the present invention, there is provided a light diffuser having anisotropy in which the diffusivity of outgoing light changes depending on the incident angle of the incoming light. The light diffusing body is characterized in that a concavo-convex structure is formed on at least one surface of the light diffusing body so as to diffuse the emitted light without depending on

The invention according to claim 2 is the light diffuser according to claim 1, wherein the concavo-convex structure is formed on the outgoing light side of the light diffuser.

The invention according to claim 3 is the light diffuser according to claim 1, wherein the concavo-convex structure is formed on the incident light side of the light diffuser.

The invention according to claim 4 is the light diffuser according to any one of claims 1 to 3, wherein the concavo-convex structure exhibits diffusion with a haze value of 60 or less.

The invention according to claim 5 is characterized in that the depth of the concavo-convex structure is 5 μm or more.
The light diffuser according to any one of 4 above.

The invention according to claim 6 is a display device characterized in that the light diffuser according to any one of claims 1 to 5 is arranged on the observation side of an image display element.

By using the light diffuser of the present invention,
Blurring can be reduced, contrast can be improved, a bright display screen can be realized, and coloring of a visible display image can be reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing an example of the configuration of a light diffuser according to the first embodiment of the present invention.
That is, the light diffuser according to the first embodiment has a configuration in which the uneven structure 2 is provided on the surface of the anisotropic diffuser 1. Then, as shown in the figure, incident light is introduced from the anisotropic diffuser 1 side, and emitted light is taken out from the concavo-convex structure 2 side.

As shown in FIG. 2, the surface of the anisotropic diffuser 1 itself does not need to have an uneven structure.
The concavo-convex structure 2 may be provided on the surface layer 3 provided adjacent to the surface of the.

The mechanism of diffusion when light is incident on the light diffuser thus constructed will be described with reference to FIGS. 3 to 5. FIG. 3 shows the scattered state of the emitted light due to the difference in the incident angle of the incident light, and the curve B shows the scattered state due to the uneven structure of the surface, and there is almost no dependence on the incident angle α of the incident light. The characteristic is that the diffusivity (%) is approximately the same for incident light incident at any incident angle α.

On the other hand, the curve A shows the scattering by the anisotropic diffuser.
Shows the state and the specific angle of incidence α ₁Entered at
Only the incident light is strongly diffused and incident at other incident angles.
It has the property that it does not diffuse much incident light.
It

Light transmitted from the uneven surface 5 side of the anisotropic diffuser 1 is weakly diffused on the uneven surface 5. The diffusion on the uneven surface 5 is a non-anisotropic (isotropic) diffusion. If the diffusion on the uneven surface 5 is strong, the anisotropy of the diffuser is impaired, so that the haze value is 60. It is desirable to exhibit the following weak diffusion.

Further, it is desirable that the diffusion on the concavo-convex surface 5 causes a strong influence of refraction due to the concavo-convex shape to change the direction of light. This is because if the concavo-convex structure 2 is fine, Rayleigh scattering, diffraction scattering, and the like occur, and the diffused light is colored. The main structure of these irregularities is preferably 5 μm or more, and more preferably 10 μm or more.

Therefore, as shown in FIG. 4, when the incident light enters the anisotropic diffuser ₁ at the incident angle α ₁ at which the anisotropic diffuser exhibits a high degree of diffusion, the anisotropic diffuser 1 1 efficiently scatters this incident light. Then, each component of the incident light scattered by the anisotropic diffuser 1 enters the uneven structure 2. The concavo-convex structure 2 further diffuses each component of the incident light scattered by the anisotropic diffuser 1 to almost the same degree regardless of the incident angle.

The incident angle α is the angle with respect to the normal direction P of the incident surface of the light diffuser (in FIG. 4, the anisotropic diffuser is applicable), as shown in FIG. is there.

On the other hand, as shown in FIG. 5, the incident angle α _{2 at} which the anisotropic diffuser 1 hardly scatters the incident light is shown.
When incident on the anisotropic diffuser 1, the anisotropic diffuser 1
Hardly scatters this incident light. Therefore, the incident light incident on the anisotropic diffuser 1 is transmitted through the anisotropic diffuser 1 with almost no diffusion and is incident on the uneven structure 2. The concavo-convex structure 2 diffuses the incident light thus incident to almost the same degree regardless of the incident angle. Although the anisotropic diffuser 1 and the concavo-convex structure 2 are in close contact with each other in reality, in order to make the diffusion state easy to understand, FIGS.
In both cases, the anisotropic diffuser 1 and the uneven structure 2 are described as being separated from each other. However, even if they are in close contact with each other, even if they are separated, the incident light is similarly diffused by the mechanism described above.

That is, the light diffuser according to this embodiment is
As shown in the graph (A + B) of FIG. 6, an intermediate property between the characteristics of the anisotropic diffuser 1 shown by the curve A of FIG. 3 and the characteristics of the uneven structure 2 shown by the curve B of FIG. 3 is shown. That is, the anisotropic diffuser 1 having a high diffusivity for a particular angle of incidence alpha ₁
And the difference between the high diffusivity and the low diffusivity is smaller than that of the anisotropic diffuser.

Further, since both the anisotropic diffuser 1 and the concavo-convex structure 2 are provided, the diffusion degree over the entire area of the incident angle α is such that the anisotropic diffuser alone or the concavo-convex structure alone diffuses. Each is larger than the degree. The characteristics described above can be adjusted by changing the thickness of the anisotropic diffuser 1 and the depth of the unevenness of the uneven structure 2. That is, anisotropic diffuser 1
By increasing the thickness of the unevenness structure and making the unevenness of the uneven structure 2 shallower, the characteristics of the light diffuser become closer to the characteristics of the anisotropic diffuser 1, and conversely, the unevenness of the uneven structure 2 becomes deeper. Then, by reducing the thickness of the anisotropic diffuser 1, the characteristics of the light diffuser become closer to the characteristics of the uneven structure 2.

Specifically, if the depth of the concavo-convex structure 2 is 30% or less with respect to the thickness of the anisotropic diffuser 1, the anisotropic diffuser tends to have a strong tendency, so that the anisotropic diffusion is performed. When the depth of the concavo-convex structure 2 is 30% or more with respect to the thickness of the body 1,
The diffusion characteristics are similar to the uneven shape.

Next, the operation of the light diffusing plate according to this embodiment having the above-mentioned structure will be described. As shown in FIG. 4, at the incident angle α ₁ at which the anisotropic diffuser 1 exhibits a high diffusivity,
The incident light that has entered the anisotropic diffuser 1 is first efficiently scattered by the anisotropic diffuser 1, and each of the scattered components enters the uneven structure 2. Then, the light is further scattered in the uneven structure 2 and is emitted from the uneven structure 2 as outgoing light (diffused light). Since the concave-convex structure 2 diffuses the incident light to almost the same degree regardless of the incident angle, each component incident on the concave-convex structure 2 is efficiently diffused. That is, when the incident light has an incident angle α ₁ at which the anisotropic diffuser 1 exhibits a high degree of diffusion,
The incident light that has entered the anisotropic diffuser 1 is efficiently diffused and then emitted from the uneven structure 2.

On the other hand, as shown in FIG. 5, the incident angle α of the incident light is such that the anisotropic diffuser 1 hardly scatters the incident light.
_When the incident light enters the anisotropic diffuser 1 at 2, only a small amount of the incident light is scattered in the anisotropic diffuser 1 and enters the uneven structure 2. The components that have entered the concavo-convex structure 2 in this way are scattered in the concavo-convex structure 2 and exit from the concavo-convex structure 2 as outgoing light (diffused light). That is, after the incident light is incident on the anisotropic diffuser 1 at an incident angle α ₂ at which the anisotropic diffuser exhibits a low degree of diffusion, the incident light is slightly diffused as compared with the case of the concavo-convex structure 2 alone. The light is emitted from the uneven structure 2. That is, the characteristics of the light diffuser according to the present embodiment are as shown by the curve (A + B) in FIG. 6, and the characteristics of the anisotropic diffuser shown by the curve A in FIG. 3 and the unevenness shown by the curve B in the figure. It is an intermediate property to the property of the structure. That is, while the range of the incident angle that brings about high diffusivity is expanded, the difference between the high diffusivity and the low diffusivity is smaller than that of the anisotropic diffuser, and the intensity of the diffusion is relaxed.

Since both the anisotropic diffuser and the concavo-convex structure are provided, the diffusivity over the entire incident angle α is smaller than that of the anisotropic diffuser or the concavo-convex structure alone. Also grows larger. An anisotropic diffuser having a strong diffusion strength causes a problem that the diffused light is colored yellow as described in the related art. However, in the light diffuser according to the present embodiment, as described above. In addition, since the intensity of Rayleigh scattering is alleviated, diffused light with reduced yellowness can be obtained. Further, since the diffusivity becomes high over the entire range of the incident angle α, the incident light which is incident at an acute angle from the lateral direction is also efficiently diffused. The advantage of the anisotropy that the degree of diffusion is high with respect to a specific incident angle α ₁ is, as described in the related art, that when such a light diffuser is applied to a liquid crystal display device, blurring in liquid crystal display is reduced. , And increase the contrast. The light diffuser according to the present embodiment reduces the yellow tint of diffused light while maintaining such an anisotropic property, and is efficient even for incident light that is sharply incident from the lateral direction. Can spread.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. 7 to 11. FIG. 7 is a cross-sectional configuration diagram showing an example of a light diffuser according to the second embodiment of the present invention. That is, the light diffuser according to the second embodiment is configured such that the uneven structure 12 is provided on the surface of the anisotropic diffuser 11. Then, contrary to the light diffuser of the first embodiment, the incident light is introduced from the concave-convex structure 12 side,
The emitted light is taken out from the anisotropic diffuser 11 side. Light transmitted from the uneven surface 5 of the anisotropic diffuser 1 is weakly diffused at the uneven surface 15. The diffusion on the uneven surface 15 is diffusion without anisotropy. If the diffusion on the uneven surface 15 is strong, the anisotropy of the diffuser is impaired. Therefore, it is desirable that the haze value shows weak diffusion of 60 or less.

Further, it is desirable that the diffusion on the concavo-convex surface 15 has a strong influence of refraction due to the concavo-convex shape and the direction of light changes. This is because if the concavo-convex structure 15 is fine, Rayleigh scattering, diffraction scattering, and the like occur, and the diffused light is colored. The main structure of the uneven structure 12 is 5 μm.
It is preferably m or more, more preferably 10
It is desirable that the thickness is at least μm. The surface of the anisotropic diffuser 11 itself does not need to be the concavo-convex structure 12, and the surface layer 13 adjacent to the surface of the anisotropic diffuser 11 as shown in FIG.
The uneven structure 12 may be present. The mechanism of diffusion when light is incident on the light diffuser configured as described above will be described with reference to FIGS. 9 to 11.

As already described with reference to FIG. 3, as shown by the curve B, the concavo-convex structure has almost no dependency on the incident angle α of the incident light, and the incident light is incident at any incident angle. It has the property of diffusing to almost the same degree of diffusion (%). On the other hand, as shown by the curve A in FIG. 3, the anisotropic diffuser strongly diffuses only the incident light incident at a specific incident angle, and is far less than the incident light incident at other incident angles. It has the property of not diffusing. Therefore, as shown in FIG. 9, when the incident light is incident on the concave-convex structure 12 at the incident angle α ₁ at which the anisotropic diffuser 11 exhibits a high degree of diffusion, the concave-convex structure 12 first changes the incident light. Scatter efficiently. When each component of the incident light scattered by the concavo-convex structure 12 enters the anisotropic diffuser 11, the anisotropic diffuser 11 determines the incident angle of each component of the incident light scattered by the concavo-convex structure 12. Components incident on the anisotropic diffuser in the vicinity of α ₁ are efficiently diffused, and components incident at other incident angles are transmitted with almost no diffusion.

On the other hand, as shown in FIG. 10, when incident light is incident on the uneven structure 12 at an incident angle α ₂ at which the anisotropic diffuser 11 does not exhibit high diffusivity, the uneven structure 12 first receives this incident light. Scatters light efficiently. Also in this case, each component of the incident light scattered by the concavo-convex structure 12 is incident on the anisotropic diffuser 11, but the anisotropic diffuser 11 has the concavo-convex structure 12.
Of the respective components of the incident light scattered by, the components incident on the anisotropic diffuser 11 in the vicinity of the incident angle α ₁ are efficiently diffused,
Components incident at other incident angles are transmitted with almost no diffusion.

Although the anisotropic diffuser 11 and the concavo-convex structure 12 are in close contact with each other in reality, the anisotropic diffuser 11 and the anisotropic diffuser 11 are shown in FIGS. The uneven structure 12 is described as being isolated. However, even if they are in close contact with each other, even if they are separated, the incident light is similarly diffused by the mechanism described above. That is, the light diffuser according to the present embodiment is shown in FIG.
As shown by the curve (B + A) of No. 1, it shows an intermediate property between the characteristics of the anisotropic diffuser shown by the curve A of FIG. 3 and the characteristics of the uneven structure shown by the curve B of FIG. That is, the specific incident angle α
_The anisotropic diffuser 11 has the characteristics of slightly higher diffusivity than ₁ , and the difference between the high diffusivity and the low diffusivity is smaller than that of the anisotropic diffuser. However, the anisotropic diffuser 11
Since each component of the light isotropically scattered by the concavo-convex structure 12 is incident on, the dependence of the diffusion degree on the incident angle α of the incident light on the light diffuser is small. Therefore, in the case of the first embodiment as shown in FIG. 6, the characteristics of the anisotropic diffuser are relaxed as compared with the diffusion degree characteristics.

Since both the anisotropic diffuser 11 and the concavo-convex structure 12 are provided, the diffusivity over the entire area of the incident angle α is such that the anisotropic diffuser alone or the concavo-convex structure alone diffuses. Each is larger than the degree. The characteristics described above can be adjusted by changing the thicknesses of the anisotropic diffuser 11 and the uneven structure 12. That is, by increasing the thickness of the anisotropic diffuser 11 and decreasing the depth of the uneven structure 12, the characteristics of the light diffuser become closer to the characteristics of the anisotropic diffuser, and conversely, the uneven structure. By making the depth of 12 shallow and making the thickness of the anisotropic diffuser 11 thick, the characteristics of the light diffuser become closer to the characteristics of the uneven structure.

Next, the operation of the light diffusing plate according to the present embodiment having the above-described structure will be described. As shown in FIG. 9, the angle of incidence α _{1 at} which the anisotropic diffuser 11 exhibits a high degree of diffusion.
Then, the incident light incident on the concavo-convex structure is first of all
Is efficiently scattered by, and each component of the scattered light enters the anisotropic diffuser 11. In the anisotropic diffuser 11, among the components of the incident light scattered by the uneven structure 12,
Only the component incident on the anisotropic diffuser 11 near the incident angle α ₁ is efficiently scattered, and the components incident at other incident angles are hardly diffused and transmitted.

Similarly, as shown in FIG. 10, anisotropic diffusion
Incident angle α at which the body 11 exhibits a low diffusivity ₂Then, the uneven structure 12
The incident light incident on the
Efficiently scattered, each component of this scattered light is anisotropic
It is incident on the sex diffuser 11. The anisotropic diffuser 11 has unevenness
Of the components of the incident light scattered by the structure 12, the incident angle α
₁Only the component incident on the anisotropic diffuser 11 near the
For components that are well scattered and are incident at other angles of incidence
Is transmitted without being diffused. That is, the incident light
Is the incident angle α at which the anisotropic diffuser 11 exhibits a high diffusivity.₁so
Even when incident, the anisotropic diffuser 11 is still low.
Angle of incidence α₂Even when it is incident at
Of the components of the incident light diffused by the uneven structure 12,
Incident angle α₁Therefore, only the component incident on the anisotropic diffuser 11 is different.
It is diffused by the anisotropic diffuser 11 and is anisotropically expanded at other incident angles.
Most of the components incident on the diffuser 11 are diffused as they are.
It is transmitted without.

However, when the incident light is at an incident angle α ₁ , the concavo-convex structure 1
Since the proportion of the components incident on the anisotropic diffuser 11 at the incident angle α ₁ is larger in the case of incident on _{2 than} on the concave-convex structure 12 at the incident angle α ₂ , as shown in FIG. Shows slightly the characteristics of an anisotropic diffuser. That is, the characteristic of the light diffuser according to the present embodiment is the curve (B +
As shown in A), the uneven structure shown by the curve B in FIG. 3 is slightly provided with the characteristics of the anisotropic diffuser.

As described above, the anisotropic characteristic of the light diffuser according to the present embodiment is smaller than that of the light diffuser 1 according to the first embodiment as shown by the curve (A + B) in FIG. So
The light diffuser according to the first embodiment can be selectively used according to the application. For example, in order to obtain the same degree of anisotropy, the light diffuser according to the first embodiment has a second
Since the thickness of the anisotropic diffuser can be made smaller than that of the light diffuser according to the embodiment of the present invention, it has a feature that the yellow tint is alleviated.

The strength or weakness of the characteristics of this anisotropic diffuser can be adjusted by changing the thickness of the uneven structure and the thickness of the anisotropic diffuser. That is, when it is desired to emphasize the characteristics of the anisotropic diffuser, by increasing the thickness of the anisotropic diffuser, or when it is not desired to emphasize the characteristics of the anisotropic diffuser, that is, When it is desired to bring the characteristics closer to those of the concavo-convex structure, the concavo-convex structure is deepened. By using the light diffusing plate having at least the concave-convex structure and the anisotropic diffuser as described in the first and second embodiments, a diffusing plate that realizes a desired diffusivity characteristic is manufactured. It becomes possible. That is, when it is desired to emphasize the characteristic of the anisotropic diffuser with respect to the diffusivity characteristic of the uneven structure, it is necessary to dispose the uneven structure on the incident side of the incident light like the light diffuser shown in this embodiment. Good.

On the other hand, when it is desired to relax the diffusivity characteristic of the anisotropic diffuser, the anisotropic diffuser is arranged on the incident side of the incident light like the light diffuser shown in the first embodiment. Just do it. Furthermore, by increasing the depth of the concavo-convex structure in each light diffuser, the characteristics of the anisotropic diffuser can be more relaxed, and by increasing the thickness of the anisotropic diffuser, The characteristics of the anisotropic diffuser can be emphasized.

The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below. That is, in the first and second embodiments, the light diffuser formed by combining at least the anisotropic diffuser and the concavo-convex structure has been described. However, as the diffusivity characteristic with respect to the light incident angle α, a desired diffusivity characteristic can be obtained. To realize 1
The light diffuser may be configured by forming an uneven structure on both sides of one anisotropic diffuser. It is understood that the light diffuser configured by appropriately combining the plurality of anisotropic diffusers and the concavo-convex structure as described above belongs to the technical scope of the present invention as a modification of the present invention.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. 12 to 13. In the third embodiment of the present invention, the light diffuser according to the first embodiment,
A liquid crystal display device to which the light diffuser according to the second embodiment is applied will be described. That is, FIG. 12 and FIG.
Reference numeral 3 denotes a liquid crystal display device to which the light diffuser according to the first embodiment (see FIGS. 1 and 2) and the light diffuser according to the second embodiment (see FIGS. 7 and 8) are applied, respectively. It is a sectional view showing an example of layer composition. These liquid crystal display devices include a polarizing plate 20, an adhesive material 21, a retardation plate 22, a light diffuser 23, a glass 24, a transparent electrode 25, and a liquid crystal layer 26.
And a reflective electrode 27 are laminated. The light diffuser 23 in FIGS. 12 and 13 is the light diffuser according to the first embodiment (see FIGS. 1 and 2) or the light diffuser according to the second embodiment (see FIGS. 7 and 8). ) Is equivalent to. The liquid crystal display device shown in FIG. 12 is an example in which the uneven surface of the light diffuser 23 is attached to the upper part of the glass 24 via the adhesive material 21. Further, a phase difference plate 22 is arranged above the light diffuser 23 with an adhesive 21 interposed therebetween.

The liquid crystal display device shown in FIG. 13 is an example in which the uneven surface of the light diffuser 33 is arranged on the incident light side. Next, the operation of the liquid crystal display device according to this embodiment configured as described above will be described. An anisotropic diffuser having a strong diffusion strength causes a problem that the diffused light is colored yellow, but the light diffusers according to the first and second embodiments alleviate the diffusion strength. By doing so, diffused light with reduced yellowness can be obtained. Further, since the diffusivity over the entire area of the incident angle α is also high, the incident light which is acutely incident from the lateral direction is also efficiently diffused. Therefore, in the liquid crystal display device according to the present embodiment to which the light diffuser having such an effect is applied, blurring in the liquid crystal display is reduced, and
An increase in contrast is provided. Further, even incident light that is incident from the lateral direction at an acute angle is efficiently diffused, so that a bright display screen is realized.

As described above, in the liquid crystal display device according to the present embodiment, due to the above-mentioned operation, it is possible to reduce the blur in the liquid crystal display and improve the contrast. Furthermore, a bright display screen can be realized.

In the liquid crystal display device according to the present embodiment, due to the above-mentioned operation, blurring in the liquid crystal display device can be reduced, contrast can be improved, and bright image display can be realized. Also,
The scattering also has the effect of expanding the viewing area of the liquid crystal display device. In the present embodiment, the uneven structure of the light diffuser is illustrated as being arranged on the back side (liquid crystal layer side) of the front polarizing plate of the liquid crystal panel, but the uneven structure is provided on the front side of the polarizing plate. It may be arranged. The uneven structure
If it is on the back side of the front polarizing plate of the liquid crystal panel, it has the advantage that the front surface of the liquid crystal display does not get dirty easily and it is easy to clean. Will have.

On the other hand, when the uneven structure is on the front side of the front polarizing plate of the liquid crystal panel, the interface with the uneven structure does not need to be an adhesive and the uneven structure and the air layer are in contact with each other. Generally, the refractive index of glass or resin is around 1.5, and the refractive index of air is around 1.0. Therefore, the difference between the refractive index of the adhesive and the uneven structure of the air layer and the uneven structure of The difference in refractive index becomes larger, high diffusion can be obtained by the fine concavo-convex structure, and since it is not necessary to select an adhesive having a refractive index different from that of the concavo-convex structure, the range of choices for the adhesive expands. Furthermore, there is an effect that the surface reflection component on the front surface of the display device is also reduced by diffusion. that's all,
Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the configurations of the embodiments.

[0046]

As described above, according to the present invention,
Optical diffusion characteristics can be adjusted by optically superimposing an isotropic light diffusion plate and an anisotropic light diffusion plate. As described above, it is possible to realize a light diffuser which is not yellowed and can realize a bright display screen, and a liquid crystal display device to which the light diffuser is applied.

[0047]

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a light diffuser according to a first embodiment.

FIG. 2 is a sectional view showing a modified example of the light diffuser according to the first embodiment.

FIG. 3 is an explanatory view showing a relationship between a light incident angle and a diffusion degree in an isotropic diffuser and an anisotropic diffuser.

FIG. 4 is an explanatory diagram illustrating a light diffusion mechanism in the light diffuser according to the first embodiment.

FIG. 5 is an explanatory diagram illustrating a light diffusion mechanism in the light diffuser according to the first embodiment.

FIG. 6 is an explanatory diagram showing a relationship between a light incident angle and a diffusivity in the light diffuser according to the first embodiment.

FIG. 7 is a sectional view showing an example of a light diffuser according to a second embodiment.

FIG. 8 is a sectional view showing a modified example of the light diffuser according to the second embodiment.

FIG. 9 is an explanatory diagram illustrating a light diffusion mechanism in the light diffuser according to the second embodiment.

FIG. 10 is an explanatory diagram illustrating a light diffusion mechanism in the light diffuser according to the second embodiment.

FIG. 11 is an explanatory diagram showing a relationship between a light incident angle and a diffusion degree in the light diffuser according to the second embodiment.

FIG. 12 is a sectional view showing an example of a layer structure of a liquid crystal display device according to a third embodiment.

FIG. 13 is a cross-sectional view showing an example of the layer structure of the liquid crystal display device according to the third embodiment.

[Explanation of symbols]

1, 11, 23 ... Anisotropic scatterer 2, 12 ... Concavo-convex structure 3, 13 ... Surface layer 5, 15 ... uneven surface 20 ... Polarizing plate 21 ... Adhesive 22 ... Retardation plate

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Claims (6)

[Claims] 1. A light diffuser having anisotropy in which the diffusivity of emitted light changes depending on the incident angle of incident light, so that the emitted light diffuses independently of the incident angle of incident light. A light diffusing body having a concavo-convex structure formed on at least one surface of the light diffusing body. 2. The light diffuser according to claim 1, wherein the uneven structure is formed on the outgoing light side of the light diffuser. 3. The light diffuser according to claim 1, wherein the uneven structure is formed on the incident light side of the light diffuser. 4. The light diffuser according to claim 1, wherein the uneven structure exhibits diffusion with a haze value of 60 or less. 5. The light diffuser according to claim 1, wherein the uneven structure has a depth of 5 μm or more. 6. A display device, wherein the light diffuser according to claim 1 is arranged on an observation side of an image display element.