JP2010134345A - Light uniforming element, and back light unit and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light uniforming element capable of making up a surface having uniform brightness by making incident light from a plurality of light sources uniform and emitting the uniform light to cause a lamp image to disappear in such a constitution that the distance between the light source and an optical element or the light uniforming element is shortened, or in such a constitution that an interval between the light sources themselves is widened, to provide an optical sheet and a backlight unit using the optical uniform element, and to provide a display device using the backlight unit. <P>SOLUTION: The light uniforming element 25 includes light deflection elements 28, a light propagation layer 23 and a light diffusion layer 26. The light deflection elements 28 are arranged opposite to the light source 41 side of the display device 70, deflect light H made incident from an incident surface of the light deflection elements 28, emits the light to the light propagation layer 23 and emits diffusion light from a light emission surface of the light propagation layer 23. A rugged shape comprising fine protrusions 26A for light diffusion is disposed on the light emission surface side 26b of the light diffusion layer 26. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element, a light uniform element, and an optical sheet used for optical path control, and more specifically, various display devices such as a transmissive screen, a liquid crystal display device, and an EL display, advertisements, electronic signboards, and the like. The present invention relates to an optical element, a light uniform element, and an optical sheet that are suitable for use in advertisement display media, solar cells, and the like.

  Liquid crystal display devices using a liquid crystal panel are widely used not only for image display means of mobile phones, personal digital assistants, and personal computer displays, but also for televisions as home appliances. Furthermore, in order to make more use of the advantages of liquid crystal display devices, it has spread to general households as an image display device for large-size information appliances that has been difficult with conventional cathode ray tube (CRT) televisions. Developments not only for increasing the size but also for increasing the brightness and reducing the thickness and weight have been proceeding at a very high speed.

  In such a liquid crystal display device, a light source is often built in the device, and in order to obtain the brightness necessary for displaying an image, a backlight unit including the light source is provided on the back side of the liquid crystal panel. It is arranged. The light source employed in this backlight unit is roughly divided into a “light guide plate light guide” that performs multiple reflections of a light source lamp such as a cold cathode tube within a flat light guide plate made of acrylic resin or the like having excellent light transmittance. "Method" (so-called edge light method) and a configuration in which a diffuser plate and an optical film having a strong light scattering property are disposed between the image display element and the light source so that a cold cathode tube or an LED is not directly visible. There is a "direct type", and in particular, the direct type is used for a display device such as a large liquid crystal display in which it is difficult to use a light guide plate.

  The light emitted from the cold cathode tube as the light source is brightest immediately above the cold cathode tube, and darkest between the cold cathode tube and the cold cathode tube. The diffusion plate used in the direct type is mainly intended to reduce the brightness unevenness (lamp image) that is the brightness of this light source, so it contains fine materials that scatter light. Various diffusion plates have been developed to meet the purpose. Moreover, since the diffusion plate plays a role of supporting the optical film disposed thereon, a thickness of about 1 to 3 mm is usually required. Furthermore, liquid crystal display devices tend to be thinner year by year, and a diffusion plate constituting the liquid crystal display device is being demanded to be thinner, and at the same time, further improvement in diffusibility has been demanded.

  As a recent trend of liquid crystal display devices, power consumption suppression for the purpose of reducing energy consumption, which is a part of countermeasures for global environmental problems, has become a major issue. In the liquid crystal display device, the power consumption of the backlight serving as the light source is the largest, and efforts to suppress the power consumption of the backlight have been made in a wide range of fields.

  One approach is to reduce the number of cold-cathode tubes, which are light sources, to reduce power consumption, and the effect of reducing power consumption is widely recognized by society. However, reducing the number of cold-cathode tubes will increase the brightness unevenness (lamp image), which is the brightness of the light source, and it will be difficult to completely erase the lamp image with the conventional combination of the diffusion plate and the optical film. It is coming. When diffusing particles are increased in the diffusing plate in order to erase the lamp image, the total light transmittance of the diffusing plate is lowered, and the luminance necessary for image display cannot be obtained. In this case, the required luminance can be obtained by strengthening the light from the cold cathode tube, which is the light source, but there is a problem in that the effect of reducing power consumption is greatly reduced by strengthening the light. become.

Patent Documents 1 to 3 disclose examples in which a lens shape is formed on a light exit surface of a diffusion plate as means for improving diffusion performance. As an example, a lens having a convex curved surface is arranged on the diffusion plate. In such a diffusing plate, it may be necessary to design the shape of the lens in accordance with the arrangement of the light sources and determine the alignment of the lens, which complicates the manufacturing process. Further, by shaping the lens shape on the light exit surface of the diffuser plate, the total light transmittance of the diffuser plate may be lowered, and it may be difficult to obtain the luminance necessary for screen display. Furthermore, there may be a problem that moire interference fringes are generated from the lens sheet disposed on the diffusion plate and the liquid crystal pixels.
JP 2007-103321 A JP 2007-12517 A JP 2006-195276 A

  The present invention has been made in view of the above problems, and can uniformly reduce and eliminate the lamp image by emitting incident light from a plurality of light sources uniformly. An object of the present invention is to provide a light uniform element capable of dealing with a case where the distance is short or a case where an interval between light sources is increased. Further, an optical sheet that improves the luminance toward the viewer side by efficiently emitting the light emitted from the light uniform device to the viewer side, and the optical sheet integrally laminated with the light uniform device An object of the present invention is to provide a backlight unit and a display device including the optical sheet.

According to a first aspect of the present invention, in the light uniform element in which a light propagation layer is provided on the light incident surface side of the light diffusion substrate, and a light deflection element is provided on the light incident surface side of the light propagation layer, the light diffusion The surface of the substrate is provided with a concavo-convex shape composed of fine light diffusing convex portions on the light emitting side surface, and the height of the light diffusing convex portions is not less than 30 μm and not more than 300 μm.
That is, according to claim 1, in a light uniform element having a structure in which a light propagation layer and a light deflection element are provided on the light incident surface side of the light diffusing substrate, fine irregularities are formed on the light emitting side surface of the light diffusing substrate. The light uniform element is provided and has a height of a convex portion of 30 μm to 300 μm. In addition to the effects of the propagation layer, the light deflection element, and the light diffusing substrate, it becomes possible to further diffuse the light at the time of light emission by defining the height of the light emitting side surface convex portion of the light diffusing substrate, As a result, it is possible to provide a light uniform element that can maintain the luminance and simultaneously erase the image of the light source.

A second aspect of the present invention is characterized in that a rising inclination angle of a side surface of the light diffusion convex portion with respect to the light diffusion base material is 40 ° or more and 85 ° or less.
That is, according to claim 2, in a light uniform element having a structure in which a light propagation layer and a light deflection element are provided on the light incident surface side of the light diffusing substrate, fine irregularities are formed on the light emitting side surface of the light diffusing substrate. The light uniform element is characterized in that the rising inclination angle of the bottom of the convex portion is 40 ° to 85 °. In addition to the effects of the propagation layer, the light deflection element, and the light diffusing substrate, by defining the rising inclination angle of the bottom of the light emitting side surface convex portion of the light diffusing substrate, the light at the time of light emission can be further diffused As a result, it is possible to provide a light uniform element that can maintain the luminance and simultaneously erase the image of the light source.

A third aspect of the present invention is characterized in that a ratio of a distance between the light diffusion convex portions and a height of the light diffusion convex portions is 30% or more and 80% or less.
That is, according to a third aspect of the present invention, in a light uniform element having a structure in which a light propagation layer and a light deflection element are provided on the light incident surface side of the light diffusing substrate, fine irregularities are formed on the light emitting side surface of the light diffusing substrate. The light uniform element is characterized in that the ratio between the interval between the convex portions and the height is 30% to 80%. In addition to the effects of the propagation layer, the light deflecting element, and the light diffusing substrate, the light diffusing light is further diffused by defining the ratio of the distance between the convex portions on the light emitting side of the light diffusing substrate and the height ratio. As a result, it is possible to provide a light uniform element that can maintain the luminance and simultaneously erase the image of the light source.

According to a fourth aspect of the present invention, the shape of the light diffusion convex portion is a convex curved lens, a curved triangular prism, and a structure in which these convex portions are combined.
That is, according to a fourth aspect of the present invention, in a light uniform element having a structure in which a light propagation layer and a light deflection element are provided on the light incident surface side of the light diffusing substrate, fine irregularities are formed on the light emitting side surface of the light diffusing substrate. The light uniform element is characterized in that the convex portion has a convex curved lens, a curved triangular prism, and a structure in which these convex portions are combined. By forming the shape as described above on the light emitting side surface, an emission surface of various angles is formed, and it becomes possible to emit light to a wider range, so that the diffusion performance is improved and the image of the light source is obtained. It is possible to provide a light uniform element that can be turned off.

According to a fifth aspect of the present invention, the light deflection element is composed of a fine light deflection unit lens, and the light deflection unit lens has a first apex that is formed by an arcuate surface and is the most projecting portion. The light deflection unit lens is formed to include a ridge line that constitutes a first apex that is a protruding portion, and the light deflection unit lens includes a first apex and a first apex extending from the first apex to the light incident surface of the light propagation layer. The first inclination at a junction where the first inclined surface is joined to the light propagation layer, the refractive index of the light propagation layer being n, the pitch of the unit lens for light deflection being P, and the first inclined surface being joined to the light propagation layer. When the angle between the tangent to the surface and the light incident surface of the light propagation layer is θ, the thickness T of the light propagation layer satisfies the following formula 1.
That is, claim 5 is a light uniform element having a structure in which a light propagation layer and a light deflection element are provided on a light incident surface side of a light diffusion base material, wherein the light deflection element has a first top portion having an arcuate surface or a ridgeline. A first inclined portion extending from the first top to the light incident surface of the light propagation layer, wherein the refractive index of the light propagation layer is n, the pitch of the light deflection elements is P, and the first inclined surface When the angle between the tangent to the first inclined surface at the junction where the light propagation layer is joined to the light incident surface of the light propagation layer is θ, the thickness T of the light propagation layer is the following number 1 is provided, The light uniform element of any one of Claim 1 to 4 characterized by the above-mentioned. By defining the light deflection element, it is possible to improve the light deflection effect from the light source, and as a result, it is possible to provide a light uniform element capable of erasing the image of the light source while maintaining the luminance. Become. Also, by defining the shape of the top of the light deflection element, it is possible to improve the light deflection effect from the light source, and as a result, a light uniform element that can maintain the brightness and at the same time erase the image of the light source is provided. It becomes possible to do.

According to a sixth aspect of the present invention, the first inclined portion has a shape including a curved first curved inclined portion, a tangent at each point of the first curved inclined portion, and light incidence of the light propagation layer The angle formed with the surface side is continuously changing from 20 degrees to 90 degrees.
That is, according to a sixth aspect of the present invention, in the light uniform element having a structure in which the light propagation layer and the light deflection element are provided on the light incident surface side of the light diffusion base material, the shape of the light deflection element is the first top portion and the first top portion. The angle formed between the tangent line at each point of the first curved inclined portion and the light incident surface side of the light propagation layer is 90 degrees or more. The light uniform element according to any one of claims 1 to 5, wherein the light uniform element continuously changes at a temperature of less than or equal to a degree. By defining the shape of the light deflection element, it is possible to improve the deflection effect of light from the light source, and as a result, to provide a light uniform element that can maintain the luminance and at the same time erase the image of the light source. It becomes possible.

According to a seventh aspect of the present invention, the light diffusing substrate has a light diffusing region dispersed in a transparent resin, and has a total light transmittance of 20% to 80%, a haze value of 95% or more, The propagation layer has a total light transmittance of 80% or more and a haze value of 95% or less.
That is, according to a seventh aspect of the present invention, in the light uniform element including the light deflection element, the light propagation layer, and the light diffusion base material, a light propagation layer is formed on a light incident surface side of the light diffusion base material, and the light propagation layer The light diffusing element is formed on the light incident surface side, and the light diffusing substrate has a light diffusing region dispersed in a transparent resin, and has a total light transmittance of 30% to 80% and a haze value of 90%. The light uniform element according to any one of claims 1 to 6, wherein the propagation layer has a total light transmittance of 80% or more and a haze value of 90% or less. By defining the total light transmittance value and haze value of the light diffusing substrate and the total light transmittance value and haze value of the propagation layer, it is possible to provide a light uniform element that can erase the image of the light source. .

An eighth aspect of the present invention is characterized in that the light deflection element, the light propagation layer, and the light diffusion base material are integrally formed by a multilayer extrusion method.
That is, according to an eighth aspect of the present invention, in the light uniform element including the light deflection element, the light propagation layer, and the diffusion base material, the light deflection element, the light propagation layer, and the light diffusion base material are integrally formed by a multilayer extrusion method. The light uniform element according to claim 1, wherein the light uniform element is a light-emitting element. By uniformly extruding the light deflection element, the light propagation layer, and the light diffusion base material, it is possible to provide a light uniform element that can erase the image of the light source with reduced manufacturing cost.

According to a ninth aspect of the present invention, the light diffusion base material and the light propagation layer are integrally formed by a multilayer extrusion method, and the light deflection element formed in a sheet shape and the light propagation layer are laminated by a fixed layer. It is characterized by being.
That is, according to a ninth aspect of the present invention, in the light uniform element including the light deflection element, the light propagation layer, and the diffusion base material, the light diffusion base material and the light propagation layer are integrally formed by a multilayer extrusion method, The light uniform element according to any one of claims 1 to 8, wherein the light deflecting element formed in (1) is laminated with a light propagation layer by a fixed layer. By fixing a sheet-shaped light deflection element with high processing accuracy, it is possible to provide a light uniform element having a light deflection element excellent in the effect of erasing the image of the light source suitable for the design.

According to a tenth aspect of the present invention, in the light uniform element according to any one of the first to ninth aspects, the light is condensed, diffused, or deflected on the concavo-convex shape formed by the fine light diffusion convex portions. A single optical film having a function of separating or a plurality of optical films having different functions are laminated.
That is, a tenth aspect of the present invention provides a light uniform element including the light deflection element, the light propagation layer, and the diffusion base material according to any one of the first aspect to the light incident surface side of the light diffusion base material. A light propagation layer surface and a light deflection element are formed, and on the light exit surface side of the diffusion base material, there is a single optical film having a function of condensing, diffusing, or deflecting and separating light, or an optical film having a different function. An optical sheet characterized in that a plurality of layers are stacked. By combining with the optical film having the function of condensing, diffusing and deflecting, it is possible to provide an optical sheet that can make the image of the light source more uniform.

According to an eleventh aspect of the present invention, in the light uniform element according to any one of the first to tenth aspects, the condensing lens and the light transmitting base material are formed on the concavo-convex shape including the fine light diffusion convex portions. The condensing lens has a plurality of unit lenses arranged at a constant pitch, the unit lens has a convex curved surface, and has an arcuate surface and the third most protruded. A top and a third inclined surface extending from the third top to the light-transmitting substrate, and the distance between the opposed third inclined surfaces gradually decreases as the third top is reached. It is characterized by being formed.
That is, claim 11 is a light uniform element composed of the light deflection element, the light propagation layer, and the diffusion base material according to any one of claims 1 to 9, and is disposed on the light incident surface side of the light diffusion base material. A light propagation layer surface and a light deflection element are formed, and an optical film composed of a condensing lens and a light transmitting base material is disposed on the light exit surface side of the diffusing base material. Arranged, the shape of the condensing lens is a convex curved surface, and has a third apex having an arcuate surface, and a third inclined surface extending from the third apex to the light transmitting substrate, The optical sheet is characterized in that the distance between the opposing third inclined surfaces gradually decreases as going to the third top.

  A twelfth aspect of the present invention is a backlight unit comprising the light uniform element according to any one of the first to ninth aspects and a light source.

  A thirteenth aspect of the present invention is a backlight unit comprising the optical sheet according to the tenth or eleventh aspect and a light source.

  According to a fourteenth aspect of the present invention, there is provided a display device comprising: an image display element that transmits / shields light in pixel units to display an image; and the backlight unit according to the twelfth or thirteenth aspect.

  The distance between the light source and the light source can be reduced by using the light uniforming element having a structure in which the light deflecting element is provided on one side of the base material surface composed of the light propagation layer and the diffusion base material described so far, and the opposite surface is provided with unevenness. It is possible to emit uniform light without uneven brightness on the screen display side even when the structure is close or the distance between the light sources is widened, and by changing the thickness and material of each layer in the multilayer structure, the light source It is possible to provide an optical uniform element that can prevent warping due to heat generated from the light. An optical sheet having a configuration in which the light uniform element and the optical film are combined by efficiently emitting light emitted from the light uniform element toward a person observing a liquid crystal display image, and a back provided with the optical sheet A light unit and a display device can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 4 are examples of schematic cross-sectional views showing the configurations of the optical element and the optical path control member according to the present embodiment and the mode of use thereof, and the scales or ratios of the respective parts do not coincide with actual ones. Moreover, it is not limited to this.
(First embodiment)

  FIG. 1 is a schematic cross-sectional view illustrating an example of an optical element, a light uniform element, a backlight unit, and a display device of the present invention. The display device 70 according to the embodiment of the present invention includes an image display element 35 and a backlight unit 55. In the backlight unit 55 according to the embodiment of the present invention, a plurality of light sources 41 are arranged in a lamp house (reflecting plate) 43, and the light according to the embodiment of the present invention is formed thereon (observer side direction F). The uniform element 25 and the optical member 2 are configured to be single or plural. The light H emitted from the light source 41 is diffused by the light uniform element 25, diffused / reflected / condensed / color-shifted by one or a plurality of optical members 2 disposed thereon, and from the backlight unit 55. The emitted light K enters the image display element 35 and is emitted to the observer side F.

  The light source 41 supplies light to the image display element 35. Therefore, as the light source 41, for example, a plurality of linear light sources can be used. As the plurality of linear light sources, for example, a plurality of fluorescent lamps, cold cathode fluorescent lamps (CCFLs), EEFLs or linearly arranged LEDs can be used. The reflection plate 43 is disposed on the opposite side of the plurality of light sources 41 from the observer side F, and reflects the light emitted in the direction opposite to the observer side F out of the light emitted from the light source 41 in all directions. Can be emitted to the observer side F. As a result, the light H emitted to the observer side F becomes light emitted almost in all directions from the light source 41. By using the reflection plate 43 in this way, the light utilization efficiency can be increased. The reflection plate 43 may be any member that reflects light with high efficiency. For example, a general reflection film, a reflection plate, or the like can be used.

  The light uniform element 25 according to the embodiment of the present invention includes a light deflection element 28, a light propagation layer 23, and a light diffusion layer 26. The light deflection element 28 is arranged toward the light source 41 side of the display device 70, deflects the light H incident from the incident surface of the light deflection element 28, and emits the light H to the light propagation layer 23. The diffused light is emitted from the light exit surface. The light diffusion layer 26 is disposed on the light source side surface 23 b of the light propagation layer 23, and irregularities are formed on the surface of the observer side F surface 26 b of the light diffusion layer 26. The light uniform element 25 described above can be used not only for a liquid crystal device but also for any device that performs optical path control, such as a rear projection screen, a solar cell, an organic or inorganic EL, and an illumination device.

FIG. 2A is a diagram for explaining the function of the light uniform element 25 according to the embodiment of the present invention. The light sources 41 are arranged in the lamp house (reflecting plate) 43 at a constant pitch in the Ve direction (the screen vertical direction). The light H emitted from the light source 41 is incident on the surface of the light uniform element 25 opposite to the viewer side F, that is, the light deflection element 28, and the surface of the light uniform element 25 on the viewer side F, that is, the light diffusion layer 26. From the uneven surface 26b on the observer side F to the observer side F. When the light diffusing performance of the light uniform element 25 is low, on the surface 26b on the viewer side F of the diffusing substrate 26, the region directly above the light source 41 appears bright, the region directly above the light source 41 appears dark, and luminance unevenness (light source image) As visible. In the light uniform element 25 according to the embodiment of the present invention, the light deflection elements 28 are arranged on the surface opposite to the observer side F, and the strong front light H incident from the light source 41 is reflected by the light deflection elements 28. The traveling direction is deflected, the incident light deflected in the light propagation layer 23 is expanded, diffused in the light diffusion layer 26 and the uneven surface 26b, and uniform light is emitted to the observer side F.
The light deflection element 28 is composed of a fine light deflection unit lens 28A, and the light deflection element 28 is preferably a lens having an uneven shape. A tangent m to the first inclined surface at a point 30 where the first inclined surface 28b of the light deflection unit lens 28A is joined to the light propagation layer 23, and a surface 23a opposite to the observer side F of the light propagation layer 23, Is set to θ, the pitch of the light deflection unit lenses 28A is P, the thickness of the light propagation layer 23 is T, and the refractive index of the light propagation layer 23 is n, it is desirable to satisfy the following formula 1.

That is, as shown in FIG. 2B, the thickness T of the light propagation layer 23 is such that the light incident on the point 30 where the first inclined surface 28b of the light deflection unit lens 28A is joined to the light propagation layer 23 is It is defined as the thickness required to be deflected by the plane of the angle θ and to expand beyond the pitch P of the light deflection unit lens 28A in the Ve direction within the light propagation layer 23. Here, the pitch P of the light deflection unit lens 28 </ b> A is defined as a distance between two points joined to the light propagation layer 23 when the light deflection element 28 is viewed in cross section. It is desirable that the pitch P of the light deflection unit lenses 28A for which Formula 1 is effective is 30 μm or more and 300 μm or less. This is because when the pitch P of the light deflection unit lenses 28A is smaller than 30 μm, the structure period approaches the wavelength, and the influence of diffraction cannot be ignored. When the pitch P of the light deflection unit lenses 28A exceeds 300 μm, there is no problem in performance, but the thickness T of the light propagation layer 23 becomes very thick. In this case, it is desirable to set the thickness of the light propagation layer 23 to be 2 mm or less.
Therefore, the front light H incident on the light deflection unit lenses 28A arranged at a constant pitch is mixed in the light propagation layer 23 by the light deflected by the light deflection unit lens 28A and diffused by the light diffusion layer 26. Injected to the observer side F. When the thickness T of the light propagation layer 23 does not satisfy Formula 1, the light deflected by the light deflecting element 28 enters the light diffusion layer 26 without being mixed, so that the diffusion performance of the light uniform element 25 is insufficient. Furthermore, it is more preferable that the light deflected by the two adjacent light deflection unit lenses 28A is mixed in the light propagation layer 23. That is, it is desirable to satisfy the following formula 2.

As shown in FIG. 2C, if the light T deflected by the two adjacent light deflection unit lenses 28A has a thickness T in which the light is mixed in the light propagation layer 23, the diffusion performance is further increased. Even when the distance to the light source 41 approaches 10 mm or less, the lamp image of the light source can be reduced / eliminated.
The light deflection unit lens 28A preferably has a triangular prism shape as shown in FIG. This is because lens molding is easy and incident light H from the front can be largely deflected. Further, a convexly curved lens shape as shown in FIG. This is because the tangent line at each point of the most projecting first apex portion 28a and the first inclined surface 28b continuously changes, so that the incident light H from the front can be deflected to various angles. The convex curved lens shape is more preferably an aspherical shape as shown in FIG. This is because the radius of curvature of the first apex portion 28a can be reduced, so that the diffusion performance is increased. Further, the light deflection unit lens 28A is preferably a curved triangular prism as shown in FIG. Since the first apex portion 28a is a ridgeline, the incident light H can always be largely deflected regardless of the position of the lens. Moreover, since the tangent line at each point of the first inclined surface 28b continuously changes, the incident light H from the front surface can be diffused to various angles. At this time, as shown in FIG. 3 (d), the angle formed by the tangent line at each point of the first inclined surface 28b and the surface 23b on the side opposite to the observer side F of the light propagation layer 23 is 20 degrees to 90 degrees. It is further desirable that it varies continuously between degrees. If there is a surface below 20 degrees, the deflection angle becomes very small, and the diffusion performance becomes weak. In particular, when there is a surface at 0 degree, the incident light H is transmitted without being deflected at all. In the curved triangular prism, there is no surface in which the angle formed by the tangent line at each point of the first inclined surface 28b and the surface 23b opposite to the observer side F of the light propagation layer 23 is smaller than 20 degrees. It can be deflected at a large angle regardless of where the light enters the surface 28b.
In addition, when the angle between the tangent line at each point of the first inclined surface 28b and the surface 23b on the opposite side of the light propagation layer 23 from the observer side F does not change significantly, at any point of the first inclined surface 28b light is emitted. Even if it is incident, since the deflection angles are almost the same, the light is concentrated in the same region. In the curved triangular prism, the angle between the tangent line at each point of the first inclined surface 28b and the surface 23b on the opposite side of the light propagation layer 23 from the observer side F greatly changes in the range of 20 degrees to 90 degrees. Therefore, the incident light H can be deflected at various angles to make the light uniform. Further, the light deflection unit lens 28A can be used by combining a plurality of the above lens shapes. For example, as shown in FIG. 3 (e), a shape in which a triangular prism is combined on a convex curved lens may be used. Alternatively, a shape in which two curved triangular prisms are shifted in the Ve direction and overlapped as shown in FIG. This is because the diffusion performance is further increased by the diffusion effect of two or more lens shapes.

  As shown in FIG. 4A, the light deflection unit lens 28A may have a concave lens shape. The concave lens shape is preferably the reverse shape of the triangular prism, convex curved lens, curved triangular prism, and other combination lenses. In this case, θ in the above formulas 1 and 2, as shown in FIG. 7, the tangent m at the point 30 where the first inclined surface 28 b joins the first apex 28 a, the observer side of the light propagation layer 23, and It is defined as an angle θ formed with the opposite surface 23a. Therefore, the definition of the thickness T of the light propagation layer 23 is the distance from the first top 28a of the concave lens to the light diffusion layer 26. Therefore, the thickness of the optical element 24 and the light uniform element 25 can be reduced as compared with the convex lens shape, which is desirable. As shown in FIG. 4B, the first apex portion 28a of the concave lens may be a substantially flat surface. This is because the flat surface has less wear and chipping of the mold for molding the light deflection unit lens 28A. Furthermore, as shown in FIG. 4C, a light diffusion / reflection layer 28c may be formed on the first top portion 28a which is a substantially flat surface. At this time, the amount of wraparound Δ on the first inclined surface 28b is desirably 30% or less of the width p1 of the first inclined surface 28b. Furthermore, as shown in FIG. 4D, an optical cover layer 28c may be formed on the concave surface of the concave lens. Since the concave surface of the concave lens is a region with a small deflection angle, the diffusion performance is improved by forming the light cover layer 28c on the concave surface. Examples of the forming method include an inkjet method and a water / oil repellent treatment method.

  The light deflection element 28 may be arranged by appropriately combining a plurality of the above-described lenses. Alternatively, as shown in FIGS. 6A and 6B, the pitch P and height of the light deflection unit lenses 28A may be changed and arranged. As a result, the farthest intersection α of the light deflection unit lens 28 </ b> A is unevenly arranged in the light propagation layer 23. FIG. 6C shows a structure in which the farthest intersection point α is arranged in parallel and on a straight line with respect to the arrangement direction of the light deflection unit lenses 28A. When the front light H is incident on the light deflection unit lens 28A, a condensing point is generated on the center line of the light deflection unit lens 28A, but aberration is generated on the center line. Therefore, in the present invention, in order to simplify the description, the point that is focused at the point farthest from the lens apex is defined as the farthest intersection point α. 6A to 6C show an example in which the farthest intersection point α is a point where light incident on both ends of the light deflection unit lens 28A is deflected and intersects.

  In FIG. 6C, for example, when all the light deflection unit lenses 28A have the same shape, the position of the farthest intersection α of the light incident on each of the light deflection unit lenses 28A exists on the same plane. To do. Accordingly, the light H incident from the incident surface of the light uniform element 25 can provide the same diffusion performance in any region, and thus the light uniform element 25 without unevenness can be provided. However, as shown in FIGS. 6A and 6B, when the lens shape of the light deflection unit lens 28A is not constant, the farthest light incident on each light deflection unit lens 28A. The intersection α does not exist on the same plane. Therefore, the thickness T of the light propagation layer 23 is different for each light deflection unit lens 28A. At this time, it is desirable to select the thickness T of the light propagation layer 23 that is the thickest among the lenses to be combined. By selecting T that is the thickest, all the light deflection unit lenses 28A that are arranged can satisfy the above-described formulas 1 and 2, so that the diffusion effect can be obtained with certainty. For example, when the light source 41 is extremely close to the light uniform element 25, when the distance between the light sources 41 is extremely far away, or when the distance between the light sources 41 is uneven, the light deflection unit lens 28A It is effective to make the farthest intersection point α non-uniform. In particular, when a plurality of combinations are combined, they may be regularly arranged in accordance with the position of the light source 41 as shown in FIG. At this time, it is desirable to dispose a light deflection unit lens 28A in which the thickness T of the light propagation layer 23 can be set to be the thinnest in the region directly above the light source 41. As a result, the diffusion performance in the region directly above the light source 41 can be improved, and thus the luminance unevenness can be further reduced. The pitch P of the light deflection unit lens 28A can be determined as appropriate. However, since the thickness T of the light propagation layer 23 increases as the pitch P of the light deflection element 28 increases, it is practically 30 μm or more and 300 μm or less, preferably It is required to be 50 μm or more and 200 μm or less.

  The light deflection element 28 can be formed on the surface 23 a opposite to the observer side F of the light propagation layer 23 using an electron beam curable resin such as a UV curable resin. For example, the light diffusion layer 26 and the light propagation layer 23 are integrally formed as a plate member by an extrusion method or the like, and the light deflection element 28 is formed on the surface 23a opposite to the observer side F of the light propagation layer 23 by UV molding. can do. Furthermore, the light propagation layer 23 is formed as a plate-like member by an extrusion method, an injection molding method, or the like, and before / after the light diffusion layer 26 is integrated with the light diffusion layer 26, the side opposite to the observer side F of the light propagation layer 23 The light deflection element 28 can be UV-molded on the surface 23a. PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), acrylonitrile styrene copolymer, acrylonitrile polystyrene copolymer, etc. The light deflection element 28 can also be formed by a press molding method. Further, the light deflection element 28 can be formed on the surface of the sheet material produced in the same manner using a radiation curable resin.

  The light deflection element 28 and the light propagation layer 23 can be simultaneously produced by extrusion. Further, as shown in FIG. 8A, the light deflection element 28 of the present invention and the light uniform element 25 composed of the light propagation layer 23 and the light diffusion layer 26 may be integrally formed by multilayer extrusion molding or the like. On the other hand, as shown in FIG. 8 (b), after being formed into a sheet shape, the light propagation layer 23 may be bonded to the surface 23a opposite to the observer side F by a fixing layer 20 by lamination or the like. it can. In this case, it is preferable to include an ultraviolet absorber in the light deflection element 28 formed into a sheet shape. By including an ultraviolet absorber in the light deflection element 28 formed into a sheet shape, it is possible to prevent peeling of the fixed layer 20 due to ultraviolet degradation.

  Here, the fixed layer 20 is formed using a pressure-sensitive adhesive or an adhesive. Urethane, acrylic, rubber, silicone, and vinyl resins can be used for the pressure-sensitive adhesive and adhesive. In addition, as the pressure-sensitive adhesive and the adhesive, those which are pressed and adhered in a one-pack type, those which are cured by heat or light can be used, and those which are cured by mixing two liquids or a plurality of liquids are used. be able to. Further, a filler may be dispersed in the fixed layer 20. By dispersing the filler in the fixed layer 20, the elastic modulus of the bonding layer can be increased. As a method for forming the fixed layer 20, there are a method of directly applying to the bonding surface and a method of pasting together those prepared in advance as a dry film. It is preferable to prepare the fixed layer 20 as a dry film because it can be easily handled in the manufacturing process.

  Further, it is desirable that the fixed layer 20 has a warping preventing action. By matching the thermal linear expansion coefficient of the fixed layer 20 so as to be substantially the same as the thermal linear expansion coefficient of the light diffusion layer 26, it is possible to prevent the light uniform element 25 itself from warping. Furthermore, the warping of the light uniform element 25 itself can be prevented by matching the thermal linear expansion coefficient of the light deflection element 28 formed into a sheet shape so as to be substantially the same as the thermal linear expansion coefficient of the light diffusion layer 26. it can. The thickness of the light deflection element 28 formed into a sheet shape is desirably 30 μm to 1 mm. Furthermore, it is desirable that it is 50 micrometers-500 micrometers. This is because if the thickness of the light deflection element 28 formed into a sheet is too thin, wrinkles or the like are generated, and if it is too thick, bonding with the light propagation layer 23 is not easy. Here, the base material region of the light deflection element 28 formed into a sheet shape can be regarded as the light propagation layer 23. Therefore, by forming the light deflection element 28 in a thick sheet shape, the thickness of the light propagation layer 23 can be reduced. Further, it can be directly bonded to the light diffusion layer 26.

  Further finer irregularities may be formed on the surface of the light deflection unit lens 28A. The fine unevenness can further enhance the deflection effect by the light deflection unit lens 28A. At this time, the surface roughness Ra is preferably in the range of 0.1 μm to 10 μm. If the concavo-convex structure is less than 0.1 μm, it is difficult to obtain a deflection effect. As a method for forming fine irregularities, for example, a method of roughening the surface of the light deflection unit lens 28A itself or the molding die by etching or sandblasting, or a molding die of the light deflection unit lens 28A, Examples thereof include a method of cutting a fine uneven shape. The light deflection unit lens 28A may not have the lens shape as described above as long as it deflects the incident light H. The light deflection unit lens 28A may not have the lens shape as described above as long as it deflects the incident light H. For example, the light deflection element 28 may be a diffusion layer made of a resin filler or bubbles. This is because the diffusion performance is improved by deflecting the incident light H by the light deflection element 28, expanding the light deflected by the light propagation layer 23, and further diffusing the light diffusion layer 26 and its uneven surface.

The light propagation layer 23 constituting the light uniform element 25 of the present invention preferably has a total light transmittance of 80% or more. If the total light transmittance is 80% or more, the luminance of the light emitted to the observer side F is not lowered. Conversely, if the total light transmittance is less than 80%, the luminance of the light emitted to the observer side F is lowered, which is not preferable. The total light transmittance is a measured value based on JIS K7361-1. The light propagation layer 23 preferably has a haze value of 95% or less. The light propagation layer 23 propagates the incident light deflected and diffused by the light deflecting element 28 effectively and makes it incident on the light diffusion layer 26. Therefore, a haze value exceeding 95% is not preferable because a sufficient light diffusion effect cannot be obtained. The haze value is a measured value based on JIS K7136.
The material used for the light propagation layer 23 is preferably a transparent resin made of a thermoplastic resin. For example, polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, Examples thereof include methyl styrene resin, fluorene resin, PET, polypropylene, acrylonitrile styrene copolymer, acrylonitrile polystyrene copolymer, and the like. Further, the light propagation layer 23 may be extended in at least one axial direction.
The light propagation layer 23 can have a multilayer structure of at least two layers. At this time, when the refractive index of the layer 23A on the light deflection element 28 side is n1, the refractive index of the layer 23B on the light diffusion layer 26 side is n2, and the refractive index of the light deflection element 28 is n0, Expression 3 is satisfied. desirable.

Equation 3 will be described with reference to FIG.
When the light H enters the light deflection unit lens 28A, the light H is deflected by the refractive index of air and the refractive index n0 of the light deflection unit lens 28A. At this time, the larger the refractive index n0 of the light deflection unit lens 28A, the larger the refraction angle. Therefore, it is desirable that the refractive index n0 of the light deflection unit lens 28A is larger. In FIG. 9A, light is emitted from the light source at the interfaces of the light deflection element 28, the layer 23A of the light propagation layer 23 on the light deflection element 28 side, and the layer 23B of the light propagation layer 23 on the light diffusion layer 26 side. When proceeding from the 41 side to the observer side F, a case where the refractive index at the interface is increased is indicated by a two-dot chain line, a case where the refractive index is not changed is indicated by a dotted line, and a case where the refractive index is reduced is indicated by a solid line. For example, when light deflected by the light deflection element 28 enters the light propagation layer 23, when n0> n1, that is, when the refractive index is low, the light is deflected in the direction shown by the solid line. Since the angle formed between the deflected light and the surface 23a opposite to the observer side F of the light propagation layer 23 is reduced, the diffusion performance is improved.

  On the other hand, when n0 <n1, that is, when the refractive index becomes high, it is deflected in the direction shown by the two-dot chain line. Since the angle formed between the deflected light and the surface 23a opposite to the observer side F of the light propagation layer 23 is increased, the diffusion performance is deteriorated. Similarly, at the interface between the layer 23A on the light deflection element 28 side of the light propagation layer 23 and the layer 23B on the light diffusion layer 26 side of the light propagation layer 23, if n1> n2, that is, the refractive index is low, the diffusion performance Will be improved. Therefore, it is desirable that the refractive index n0 of the light deflection element 28 and the refractive index n1 of the layer 23A on the light deflection element 28 side of the light propagation layer 23 are equal to each other or the refractive index n0 of the light deflection element 28 is larger. The refractive index n1 of the layer 23A on the light deflection element 28 side of the light propagation layer 23 is equal to the refractive index n2 of the layer 23B on the light diffusion layer 26 side of the light propagation layer 23, or the light deflection element 28 of the light propagation layer 23 is the same. It is desirable that the refractive index n1 of the side layer 23A is larger.

  Here, it is more desirable that the thickness of the layer 23B on the light diffusion layer 26 side of the light propagation layer 23 is thicker than the thickness of the layer 23A on the light deflection element 28 side of the light propagation layer 23. This is because light can be greatly expanded in the layer 23B of the light propagation layer 23 on the light diffusion layer 26 side. Furthermore, as shown in FIG. 9B, the point where the light incident on both ends of the light deflection unit lens 28A of the light deflection element 28 is deflected and intersected is on the light deflection element 28 side of the light propagation layer 23. Desirably located in layer 23A. Further, when the light propagation layer 23 has a multilayer structure of at least two layers, the farthest intersection α of the light deflection unit lens 28A is the light exit surface of the light deflection element 28 (that is, the observer side of the light propagation layer 23). It may be included in the layer in contact with the surface 23a) opposite to F. As a result, since the farthest intersection point is at a point close to the light deflection element 28 in the light propagation layer 23, light can be diffused greatly.

  The light propagation layer 23 described above can be formed by a plurality of layers having different refractive indexes by a multilayer extrusion method or the like. Further, the light deflection element 28 is formed into a sheet shape using a material having a refractive index higher than that of the light propagation layer 23 on the light propagation layer 23 formed by an extrusion method or an injection molding method, and is bonded by a lamination method or the like. Can also be realized.

  The light propagation layer 23 can be prevented from warping by having a multilayer structure. In this case, warping of the light uniform element 25 can be prevented by adjusting the thermal linear expansion coefficient of the layer farthest from the viewer side to approximately the same as the thermal linear expansion coefficient of the light diffusion layer 26. Further, the warpage of the light uniform element 25 can also be prevented by adjusting the thickness of the light propagation layer 23.

  The light uniform element 25 may be formed by integrating the light diffusion layer 26 and the light propagation layer 23 separately by an extrusion method, injection molding, or the like, and then integrating them with an adhesive or an adhesive material. For example, as the adhesive material or the pressure-sensitive adhesive material, the light diffusion layer 26 and the light propagation layer 23 can be bonded using a generally used laminate or the like.

  The light uniform element 25 of the present invention is characterized in that the light exit surface side 26b of the light diffusion layer 26 is provided with a concavo-convex shape composed of fine light diffusion convex portions 26A. As shown in FIG. 10, the unevenness is imparted to the emission surface 26 b of the light uniform element 25, so that various angles can be obtained compared to the case where the light emission surface side 26 b of the light diffusion layer 26 is substantially flat. By forming the emission surface, it is possible to emit light over a wider range, thereby improving the diffusion performance and reducing / extinguishing the lamp image. Typical methods for forming such irregularities include extrusion molding, mat processing, embossing, transfer or bonding, etching, and physical blasting such as sandblasting, electrical discharge, and cutting. As an example. In the above method, in the extrusion molding method, the shape of the member is transferred by pressing the transparent resin softened by heating against a metal plate or other member plate having a shape opposite to the required unevenness. Thereafter, the transparent resin can be cooled and cured to obtain an uneven shape. In addition, as another method, transparent particles having a particle size of about 50 to 500 μm may be blended in a molten transparent resin, and the transparent particles may be extruded to the outermost layer side to produce an uneven shape on the surface. . When this method is used, it is preferable that the refractive indexes of the transparent resin and the transparent particles are equal.

  As a method of forming the uneven shape other than the above, a method of forming by using an electron beam curable resin such as a UV curable resin as in the light deflection element 28, or a method of forming by an injection molding method or a hot press molding method. Can also be used. As an example, an integrated plate-like member made up of the light diffusion layer 26 and the light propagation layer 23 is produced by an extrusion molding method or the like, and the function of exerting the respective functions on the surface of the light propagation layer 23 and the light diffusion layer 26 is set. The light uniform element 25 can also be formed by bonding the light deflection element 28 having the above-described shape and the sheet having the concavo-convex shape by using an adhesive or an adhesive.

  The light diffusion convex portion 26A constituting the concave-convex shape of the light emission side surface 26b of the light diffusion layer 26 is desirably a convex curved lens, a curved triangular prism, and a combination of these concave and convex portions. Further, the height H of the light diffusion convex portions 26A is more preferably 30 μm or more and 300 μm or less. Diffusing performance is improved by making it possible to emit light over a wider range by forming the exit surface at various angles when the height H of the light diffusion convex portion 26A is within the above range. In addition, the lamp image can be reduced / eliminated. Furthermore, when a plurality of concave and convex shapes are combined, the height H of the light diffusion convex portion 26A may be the same, or the height H of each light diffusion convex portion 26A may be different. Here, when the height H of the light diffusing convex portion 26A is less than 30 μm, a sufficient diffusion effect cannot be obtained, and when it exceeds 300 μm, the mold release is reduced during processing and the manufacturing speed is slowed down. This is undesirable because it is difficult to control the shape.

  The rising inclination angle of the side surface of the light diffusion convex portion 26A on the light emitting side surface 26b of the light diffusion layer 26 is preferably 40 ° or more and 85 ° or less. By making the height of the light diffusing convex portion 26A within the above range, it is possible to emit light to a wider range by forming the emission surface at various angles. Furthermore, when a plurality of uneven shapes are combined, the rising inclination angle of the side surface of the light diffusion convex portion 26A may be the same, or the respective inclination angles may be different. In addition, when the rising inclination angle of the side surface of the light diffusion convex portion 26A is less than 40 °, a sufficient diffusion effect cannot be obtained, and when it exceeds 85 °, processing becomes difficult and shape control becomes difficult. Not desirable.

  Further, it is desirable that the ratio between the height and the distance between the light diffusion convex portions 26A on the light emitting side surface 26b of the light diffusion layer 26 is 30% or more and 80% or less. By making the height of the light diffusing convex portion 26A within the above range, it is possible to emit light to a wider range by forming the emission surface at various angles. Furthermore, when a plurality of concave and convex shapes are combined, the ratio between the interval and the height of the light diffusion convex portions 26A may be the same, or the respective ratios may be different. Further, when the ratio between the distance and the height of the light diffusion convex portion 26A is outside the above range, it is not desirable because it becomes difficult to process and the shape is difficult to control.

  As a characteristic of the light diffusion layer 26, the total light transmittance is preferably 20% or more and 80% or less. When the total light transmittance is less than 20%, the luminance of the emitted light to the observer side F is lowered, which is not preferable. Conversely, when the total light transmittance exceeds 80%, the diffusion performance is low. This is not preferable because it becomes insufficient and the uniformity of in-plane luminance deteriorates. The light diffusion layer 26 preferably has a haze value of 95% or more. When the haze value is less than 95%, the diffusion performance is insufficient, and the uniformity of in-plane luminance is deteriorated.

  The light diffusion layer 26 includes a transparent resin and a light diffusing agent mixed and dispersed in the transparent resin, and the refractive index of the transparent resin and the light diffusing agent are different. It is said that. As the transparent resin, a thermoplastic resin, a thermosetting resin, or the like can be used. For example, a styrene resin, a polycarbonate resin, a methacrylic resin, a methyl methacrylate resin, glass, a vinyl chloride resin, a polyethylene resin. , Polypropylene resin, polyester resin, fluorene resin, polyethylene terephthalate (PET), polypropylene, acrylonitrile styrene copolymer, acrylonitrile polystyrene copolymer, alicyclic acrylic resin, alicyclic polyolefin resin, olefin / maleimide alternating copolymer A polymer, a cyclohexadiene polymer, an amorphous polyester resin, an amorphous fluorine resin, or the like can be used. In addition, you may be comprised from 1 type of these, and what was comprised combining 2 or more types may be sufficient.

  The light diffusion region contains light diffusion particles, and it is desirable to easily obtain suitable diffusion performance. As the light diffusing particles, transparent particles made of an inorganic oxide or a resin can be used. As the transparent particles made of an inorganic oxide, for example, silica, alumina, titanium oxide, calcium carbonate, barium sulfate and the like can be used. The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine / formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Fluoropolymer particles such as fluoroethylene / hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene / tetrafluoroethylene copolymer), silicone resin particles, and the like can be used. Moreover, you may use combining 2 or more types of transparent particles from the transparent particle mentioned above. Furthermore, the size and shape of the transparent particles are not particularly defined. The mixing ratio of the transparent resin and the light diffusing agent can be prepared as, for example, 9: 1 by weight, but is not limited thereto and can be changed as appropriate. And the plate-shaped diffusion base material 26 is shape | molded by performing melt extrusion molding or injection molding to the mixture of transparent resin and light-diffusion agent of this molten state.

  The layer thickness of the light diffusing layer 26 is set to 0.1 to 5 mm, and most preferably 0.1 to 3 mm. When the thickness of the light diffusion layer 26 is less than 0.5 mm, the diffusion performance is insufficient, and the strength of the light diffusion layer 26 itself cannot be ensured. On the other hand, when the thickness exceeds 5 mm, the amount of resin is large, so that the luminance is reduced due to absorption, and the backlight unit 55 and the display device 70 cannot be made thinner, and at the same time, the weight is hindered. Note that the light diffusion layer 26 may be formed of a single layer or a multilayer of two or more layers.

  The light uniform element 25 is more preferably formed by integrally forming the light diffusion layer 26, the light propagation layer 23, and the light deflection element 28 by a multilayer extrusion method. The light uniform element 25 may be extended in at least one axial direction. By using the multilayer extrusion method, the manufacturing process can be simplified and made more efficient, and the manufacturing cost can be reduced.

  The display device 70 according to the embodiment of the present invention includes an optical film having a function of condensing or diffusing light, or an optical film having a function of deflecting and separating, which is combined on the light uniform element 25 described above. By using a single or a plurality of laminated optical films having different functions, the brightness on the viewer side F is improved by using the light K with improved condensing / diffusing characteristics, and the viewing angle direction of the light intensity Can be displayed on the image display element 35 with a smooth distribution and a reduced lamp image.

  The optical member 2 configured on the light uniform element 25 of the present invention improves the luminance by using an optical film that collects light to improve luminance, a light diffusion film that diffuses light, and a light separation function. The film to be made can be cited as a representative. By combining with these optical members, the light K in which the image of the light source is made uniform in the light uniform element 25 can be made brighter and the viewing angle can be widened, and the light K with improved light collection and diffusion characteristics. By guiding to the image display element 35, it becomes possible to display an excellent image.

  A display device 70 according to an embodiment of the present invention is an image display element 35 that defines a display image according to transmission / light-shielding in pixel units, and improves the light collection and diffusion characteristics by the backlight unit 55 described above. Therefore, the luminance on the viewer side F can be improved, the distribution of the light intensity in the viewing angle direction can be smoothed, and an image with a reduced lamp image can be obtained.

  In the display device 70 according to the embodiment of the present invention, the image display element 35 is a liquid crystal display element, and the light K whose light collection / diffusion characteristics are improved by the backlight unit 55 described above is used. It is possible to improve the brightness of the person side F, smooth the distribution of the light intensity in the viewing angle direction, and obtain an image with a reduced lamp image.

Hereinafter, the present invention will be described in detail based on examples. In addition, this invention is not limited only to these Examples.
[Example]

  Hereinafter, the optical characteristics of the display device 70 using the light uniform element 25 and the optical sheet 52 of the present invention will be described in Examples.

  As the light deflection element 28, the pitch P of the convex lenticular lens which is the light diffusion convex portion 26A is 100 μm, the tangent m at the junction 30 between the light propagation layer 23 and the convex lenticular lens, the observer side of the light propagation layer 23, A convex lenticular lens made of a UV curable resin was prepared in which the angle θ formed with the opposite surface 23a was 65 degrees and the height of the convex lenticular lens was set to 60 μm. Further, a diffusion / transparent layer plate made of polycarbonate (refractive index = 1.59) having a thickness of 2 mm, which is composed of the light propagation layer 23 and the light diffusion layer 26 was produced.

Example 1
The surface of the light diffusion layer on the light propagation layer side of the polycarbonate diffusion / transparent layer plate having a thickness of 2 mm configured with the thickness of the light propagation layer 23 set to 1.5 mm and the light diffusion layer 26 set to 0.5 mm A convex curved shape in which the height of the light diffusing convex portion 26A is 80 μm and the interval between the light diffusing convex portions 26A is 200 μm was produced using a mold during extrusion molding. The light uniform element 25 was produced by attaching a convex lenticular lens made of UV curable resin, which is the light deflection element 28, to the transparent layer side of the diffusion / transparent layer plate using an adhesive material.

(Example 2)
Using a method similar to that of the convex lenticular lens as the light deflection element 28, a convex curved shape made of UV curable resin in which the height of the light diffusion convex portion 26A is 100 μm and the distance between the light diffusion convex portions 26A is 240 μm. A sheet of was prepared. Adhesive material is applied to the light diffusion layer surface of the diffusion / transparent layer plate made of polycarbonate in which the thickness of the light propagation layer 23 is set to 1.5 mm and the thickness of the entire light diffusion layer 26 is set to 0.5 mm. Pasted together. Next, a convex lenticular lens made of UV curable resin was bonded to the light propagation layer side to produce a light uniform element 25.

(Comparative Example 1)
A pressure-sensitive adhesive is used on the light propagation layer side of the polycarbonate diffusion / transparent layer plate having a thickness of 2 mm, which is configured by setting the thickness of the light propagation layer 23 to 1.5 mm and the thickness of the light diffusion layer 26 to 0.5 mm. A convex lenticular lens made of a UV curable resin, which is the light deflection element 28, was bonded to produce a light uniform element 25 having no uneven shape on the light diffusion layer surface.

  A structure in which a diffusion film, a 90-degree triangular prism sheet, and a diffusion film were stacked in this order on the surface of the observer side F of the light uniform element 25 manufactured as described above was prepared. These are arranged in the backlight 56 having a CCFL interval of 38 mm, and the distance between the CCFL and the light uniform element 25 is 15 mm, and the liquid crystal panel 35 is arranged on the observer side F of the backlight 56, whereby the display device 70 is arranged. Assembled.

(Comparative Example 2)
In the above display device, the diffusion / made of polycarbonate having a thickness of 2 mm, in which the light deflecting element and the light propagation layer 23 having no uneven shape are set to a thickness of 1.5 mm and the light diffusion layer 26 is set to a thickness of 0.5 mm. A display device having a configuration in which a diffusion film, a 90-degree triangular prism sheet, and a diffusion film were stacked in this order on the light diffusion layer surface of the transparent layer plate was assembled.

(Optical evaluation)
The display devices of this example and comparative example were evaluated by the following measuring methods.
(Front brightness evaluation)
The display device 70 was set to all white display, and the center of the screen was measured with a spectral radiance meter (SR-3A: manufactured by Topcon Technohouse).
(Luminance unevenness evaluation)
The display device 70 was displayed as all white, and the entire screen was measured with a luminance unevenness measuring device (ProMetric 1200: manufactured by Radiant Imaging), and analysis was performed on the arrangement of a plurality of cold-cathode tubes using luminance distribution data in the vertical direction. Since the luminance distribution can be obtained as a wave distribution corresponding to the cold cathode fluorescent lamps, the luminance data corresponding to the five cold cathode fluorescent lamps at the center is extracted to calculate the average luminance, and then the luminance change with respect to the average luminance is calculated. (%) Was calculated. When the standard deviation σ of the luminance change was within 1%, it was determined that the diffusibility of the optical sheet was good.

Table 1 shows the measurement results of this example and the comparative example.
(Table 1)
In Example 1, there was no decrease in luminance, and no light source image was observed.
In Example 2, there was no decrease in luminance, and no light source image was observed.
In Comparative Example 1, there was no decrease in luminance, and the light source image was hardly recognized.
In Comparative Example 2, there was no decrease in luminance, but the light source image was easily recognized.

  In Examples 1 and 2, no decrease in luminance was observed, no image of the cold cathode tube of the light source with a wide interval was observed, and a surface with uniform brightness could be confirmed through the liquid crystal panel. On the other hand, although no decrease in luminance was observed in Comparative Example 1 and no image of the cold cathode tube of the light source with a wide interval was observed, the brightness of the surface seen through the liquid crystal panel compared to Examples 1 and 2 A difference was observed in the uniformity. Accordingly, it has been clarified that by providing an uneven shape on the surface of the light diffusing layer of the light uniform element, the surface of the light source can be erased and a uniform brightness can be created.

  In Comparative Example 2, the image of the cold cathode tube of the light source with a wide interval was easily recognized, and the effect of the light deflection element and the light uniform element having the uneven shape was clearly clarified.

  Therefore, based on the evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2, the light uniformity has a structure in which the light propagation layer and the light deflection element are provided on the light incident surface side, and the fine uneven shape is provided on the light emission side surface. It has been found that the element is effective in erasing the image of the cold cathode tube, which is a light source with a wide interval, and creating a surface with uniform brightness without causing a decrease in luminance.

It is a cross-sectional schematic diagram of the display apparatus which is embodiment of this invention. (A) It is a cross-sectional schematic diagram of the light uniform element which is embodiment of this invention, (b) It is a figure explaining Numerical formula 1, (c) It is a figure explaining Numerical formula 2. FIG. (A) It is a figure which shows an example of the lens shape of an optical deflection element, (b) It is a figure which shows an example of the lens shape of an optical deflection element, (c) It is a figure which shows an example of the lens shape of an optical deflection element. (D) It is a figure which shows an example of the lens shape of an optical deflection element, (e) It is a figure which shows an example of the lens shape of an optical deflection element, (f) It is a figure which shows an example of the lens shape of an optical deflection element. is there. (A) It is a figure which shows an example of the lens shape of an optical deflection | deviation element, (b) It is a figure which shows an example of the lens shape of an optical deflection | deviation element, (c) Light diffusion / reflection layer in the 1st top part of an optical deflection element (D) is a diagram showing an example in which a light diffusing / reflecting layer is formed in the concave portion of the light deflection element. (A) It is a figure explaining Numerical formula 1 in case a light deflection element is a concave lens, (b) It is a figure explaining Numerical formula 2 in case a light deflection element is a concave lens. (A) It is a figure explaining the case where the lens height and pitch of a light deflection element are not constant, (b) It is a figure explaining the case where the lens height of a light deflection element is not constant, (c) of a light deflection element It is a figure explaining the case where lens height and pitch are constant. It is a figure which shows an example at the time of aligning a light deflection | deviation element with a light source. (A) It is a figure which shows the form at the time of integrally forming an optical uniform element, (b) It is a figure which shows the form at the time of shape | molding an optical deflection | deviation element in a sheet form. (A) It is a figure explaining the light ray in case a light propagation layer is a multilayer structure, (b) It is a figure explaining the light ray in case a light propagation layer is a multilayer structure. (A) It is a figure explaining the effect by which the unevenness | corrugation was shaped on the emission surface of the light uniform element, (b) It is a figure explaining the case where the emission surface of a light uniform element is flat. (A) It is a figure which shows an example of the lens shape of a light-diffusion lens, (b) It is a figure which shows an example of the lens shape of a light-diffusion lens, (c) It is a figure which shows an example of the lens shape of a light-diffusion lens. (D) It is a figure which shows an example of the lens shape of a light-diffusion lens, (e) It is a figure which shows an example of the lens shape of a light-diffusion lens.

Explanation of symbols

  H, K: light, P: light deflection element pitch, p1: light deflection element first inclined surface pitch, m: tangent, T: thickness of light propagation layer, θ: angle formed by one surface of light propagation layer and tangent m , Θ1, θ2, θ3... Angles formed between tangents at each point of the light deflection element and one surface of the light propagation layer, n... The refractive index of the light propagation layer, n0. Refractive index of the first layer, n2 ... refractive index of the second layer of the light propagation layer, F, F '... observer side, X ... planar view direction, Ve ... image display device vertical direction, Ho ... image display device horizontal direction , Θ41: angle formed by the axial direction j of the lenticular lens with the axial direction k of the linear light source, Δ: light diffusion / reflection layer wrapping amount, α: farthest intersection point, 2 ... optical member, 13 ... valley, 16 ... Condensing lens, 16a ... third apex, 16b ... third inclined surface, 17 ... light transmitting substrate, 17a ... surface opposite to the observer, 17b ... view 21 (fixed layer), 21 ... light diffusion lens, 21a ... second apex, 21b ... second inclined surface, 22 ... light mask, 23 ... light propagation layer, 23a ... opposite to observer Side surface, 23b ... Observer side surface, 23A ... Light deflection element side layer of light propagation layer, 23B ... Diffusion substrate side layer of light propagation layer, 25 ... Light uniform element, 26 ... Light diffusion layer, 26a: Surface opposite to the observer, 26b: Surface on the observer side (uneven surface), 28: Light deflection element, 28a: First top, 28b: First inclined surface, 28c: Light diffusion / reflection layer, 30 DESCRIPTION OF SYMBOLS Joining point 31, 33 ... Polarizing plate, 32 ... Liquid crystal panel, 35 ... Image display element, 41 ... Light source, 43 ... Reflecting plate (reflection film), 52 ... Optical sheet, 55 ... Backlight unit, 70 ... Display apparatus .

Claims (14)

In the light uniform element in which the light propagation layer is provided on the light incident surface side of the light diffusion base material, and the light deflection element is provided on the light incident surface side of the light propagation layer,
The light diffusing base material is provided with a concavo-convex shape consisting of fine light diffusing convex portions on the light emitting side surface,
The height of the light diffusion convex portion is not less than 30 μm and not more than 300 μm.
An optical uniform element characterized by the above.   The light uniform element according to claim 1, wherein a rising inclination angle of a side surface of the light diffusion convex portion with respect to the light diffusion base material is 40 ° or more and 85 ° or less.   3. The light uniform element according to claim 1, wherein a ratio of a distance between the light diffusion convex portions and a height of the light diffusion convex portions is 30% or more and 80% or less.   4. The light uniform element according to claim 1, wherein the light diffusion convex portion has a convex curved lens, a curved triangular prism, and a structure in which these convex portions are combined. 5. The light deflection element is composed of a fine unit lens for light deflection,
The light deflection unit lens is formed of an arcuate surface and has a first apex that is the most protruding portion or is formed to include a ridge line constituting the first apex that is the most protruding portion,
The light deflection unit lens includes the first apex portion and a first inclined portion extending from the first apex portion to the light incident surface of the light propagation layer, wherein a refractive index of the light propagation layer is n, and the light The deflection unit lens pitch is P, and the angle between the tangent to the first inclined surface at the junction where the first inclined surface is bonded to the light propagation layer and the light incident surface of the light propagation layer is θ. The light uniform element according to any one of claims 1 to 4, wherein the thickness T of the light propagation layer satisfies the following formula (1).

  The first inclined portion has a curved first curved inclined portion, and an angle formed between a tangent at each point of the first curved inclined portion and a light incident surface side of the light propagation layer is 20 6. The light uniform element according to claim 5, wherein the light uniform element continuously changes at an angle of not less than 90 degrees and not more than 90 degrees.   The light diffusion substrate has a light diffusion region dispersed in a transparent resin, has a total light transmittance of 20% to 80%, a haze value of 95% or more, and the light propagation layer has a total light transmittance. The light uniform element according to claim 1, which has a haze value of 80% or more and 95% or less.   The light uniform element according to any one of claims 1 to 7, wherein the light deflection element, the light propagation layer, and the light diffusion base material are integrally formed by a multilayer extrusion method.   The light diffusion substrate and the light propagation layer are integrally formed by a multilayer extrusion method, and the light deflection element formed in a sheet shape and the light propagation layer are laminated by a fixed layer. The light uniform element according to any one of 1 to 8.   The optical uniform element according to any one of claims 1 to 9, wherein an optical film having a function of condensing, diffusing, or deflecting and separating light on the concavo-convex shape including the fine light diffusing convex portions. An optical sheet comprising a plurality of optical films having a single function or different functions.   11. The light uniform element according to claim 1, wherein an optical film comprising a condensing lens and a light-transmitting substrate is disposed on the concavo-convex shape comprising the fine light diffusing convex portions. The condensing lens includes a plurality of unit lenses arranged at a constant pitch, and the shape of the unit lenses is a convex curved surface, having an arcuate surface and the most protruding third top, and the third top A third inclined surface that reaches the light-transmitting substrate, and is formed such that the distance between the opposed third inclined surfaces gradually decreases as going to the third top portion. An optical sheet.   A backlight unit comprising the light uniform element according to claim 1 and a light source.   A backlight unit comprising the optical sheet according to claim 10 and a light source.   14. A display device comprising: an image display element that transmits and blocks light in pixel units to display an image; and the backlight unit according to claim 12 or 13.

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