JP2010250987A - Light uniforming element, optical sheet, backlight unit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extinguish a lamp image to create a surface with uniform brightness, in a structure with a short distance between a light source and an optical element or light uniforming element or in a structure with an extended space between light sources, by uniforming and emitting incident lights from a plurality of light sources. <P>SOLUTION: The light uniforming element 25 includes a light deflecting element 28, a light propagation layer 23 for propagating the light emitted from the light deflecting element 28, and a light diffusion layer 26 for diffusing the light emitted from the light propagation layer 23, and uniforms, when emitting the light from a light emitting surface of the light diffusion layer 26, the luminance on a plane facing the light emitting surface in parallel. The light deflecting element 28 includes a light transmissive substrate 28g constituting the light emitting surface side of the element 28 and a plurality of light diffusing unit lenses 28b aligned at a fixed pitch P with a constant space d on the light incident surface side of the substrate 28g. The space d is set to 3% or more and 20% or less of the pitch P of the light diffusion unit lenses. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light uniform element used for optical path control such as an optical device for an image display optical system, an optical sheet using the same, a backlight unit, and a display device, and in particular, light is emitted from a light emission surface of a light diffusion layer. It is related with the improvement of the light uniform element which makes uniform the brightness | luminance on the surface parallel and opposite to a light-projection surface.

  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.
In addition, as a recent trend of liquid crystal display devices, suppression of power consumption for the purpose of reducing energy consumption, which is 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 the 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. In addition, by providing a lens shape on the light exit surface of the diffusion plate, the total light transmittance of the diffusion 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. Furthermore, an optical sheet formed by integrally laminating an optical film that improves the luminance toward the viewer side by efficiently emitting the light emitted from the light uniform device to the viewer side, It is another object of the present invention to provide a backlight unit and a display device including the optical sheet.

In order to solve the above problems, the invention of claim 1 is directed to a light deflection element that deflects and emits incident light, and a light that is provided on a light emission surface of the light deflection element and that is emitted from the light deflection element. And a light diffusion layer that is provided on a light emission surface of the light propagation layer and diffuses light emitted from the light propagation layer, and the light is the light deflection element, the light propagation layer, and the light. When the light is transmitted through the diffusion layer and emitted from the light exit surface of the light diffusion layer, the light uniform element for uniformizing the luminance on the surface facing and parallel to the light exit surface, wherein the light deflection element comprises: A light-transmitting base material constituting the light exit surface side of the light deflection element, and a plurality of light diffusion unit lenses arranged at a constant pitch with a constant gap on the light incident surface side of the base material The gap is not less than 3% and not more than 20% of the pitch of the light diffusion unit lens. It is characterized in.
According to a second aspect of the present invention, in the light uniform element according to the first aspect, the surface of the gap is flat.
In the present invention, it is desirable to provide the light deflection element on the incident light source side, and it is desirable to arrange a light diffusion unit lens capable of diffusing an image of the light source in the light deflection element.
On the other hand, when the light diffusing unit lenses are arranged without gaps on the light incident surface of the light diffusing layer, a problem of lowering the front luminance occurs, but by providing a gap between the light diffusing unit lenses adjacent to each other, The amount of front luminance can be adjusted. As a result, it is possible to provide a light uniform element that can maintain the luminance and at the same time erase the image of the light source. Furthermore, by using a method in which light deflecting elements are scattered, only incident light desired to diffuse the light deflecting elements can pass through regions having different optical refractive indices, which gives freedom in optical design. It can be expanded.

According to a third aspect of the present invention, in the light uniform element according to the first or second aspect, the ratio of the thickness of the light diffusion layer to the sum of the thickness of the light diffusion layer and the thickness of the light propagation layer is 5 % Or more and 30% or less.
In the present invention, the light beam diffused by the light deflecting element is sufficiently diffused by passing through the light propagation layer, and further, the light beam emitted from the light propagation layer passes through the light diffusion layer, resulting in luminance. 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.

According to a fourth aspect of the present invention, in the light uniform element according to any one of the first to third aspects, the light diffusing unit lens includes a top portion, an inclined surface that faces the surface of the gap from both sides of the top portion, and The inclined surface has a skirt that intersects the surface of the gap, and is configured such that a cross-sectional area when the light diffusing unit lens is viewed in a transverse direction decreases from the skirt to the top. And
In the present invention, the light beam emitted from the light source is once focused at the focal point by using a convex or triangular prism-shaped light diffusion unit lens for the light deflection element provided on the light incident surface side of the light diffusion layer. It becomes a light beam that continues to diffuse. Therefore, it can easily serve as a light diffusion unit lens.

The invention according to claim 5 is the light uniform element according to claim 4, wherein a straight line connecting between the top and the one skirt, and a straight line connecting between the top and the other skirt. Is characterized in that the angle θ is between 20 ° and 70 °.
In the present invention, it is possible to increase the diffusion efficiency after the light beam emitted from the light source is incident on the light diffusion unit lens that is the light deflection element. Furthermore, since light rays incident from a certain angle cause a total reflection effect, it is easy to increase the luminance at a portion located between the light sources on the light exit surface of the diffusion layer of the light uniform element.

A sixth aspect of the present invention is the light uniform element according to any one of the first to third aspects, wherein each of the light diffusing unit lenses includes a lens group in which a plurality of convex fine lenses are arranged at a constant pitch. It is characterized by being.
In the present invention, since the light diffusing unit lens is composed of a plurality of fine lens groups, a plurality of lenses having different characteristics can be included in the light diffusing unit lens. An optical uniform element can be formed as a structure having a plurality of microlenses having different diffusion performances. Accordingly, it is possible to provide a light uniform element that can maintain the luminance as a result and at the same time erase the image of the light source.

A seventh aspect of the present invention is the light uniform element according to any one of the first to sixth aspects, wherein light scattering particles are dispersed and blended inside the base material and inside the light diffusion unit lens. And
In the present invention, the diffusion function by the light scattering particles of the base material and the light diffusing unit lens is improved, and 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 an eighth aspect of the present invention, in the light uniform element according to any one of the first to seventh aspects, the light deflection element, the light propagation layer, and the light diffusion layer are integrally formed by a multilayer extrusion method. Features.
In the present invention, 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.

  A ninth aspect of the invention is the light uniform element according to any one of the first to eighth aspects, wherein an optical film for diffusing light emitted from the light exit surface is provided on the light exit surface of the light diffusion layer. The optical film is fixed on the light-transmitting substrate disposed on the light-emitting surface side of the light-diffusing layer, and on the surface of the light-transmitting substrate opposite to the light-emitting surface of the light-diffusing layer. A plurality of light diffusing lenses arranged at a pitch, the light diffusing lens having a top portion and inclined surfaces respectively directed from both sides of the top portion to the light transmissive substrate, and the light diffusing lens includes the light diffusing lens. The cross-sectional area when the lens is viewed in a transverse direction is configured to decrease from the light transmitting base toward the top.

Invention of Claim 10 is an optical sheet, Comprising: The light uniform element of any one of Claims 1 thru | or 9,
And a single or a plurality of optical members disposed on the light exit surface side of the light uniform element and having a function of collecting, diffusing, reflecting, or deflecting and separating light.
In the present invention, an optical sheet that can make the image of the light source more uniform can be provided by combining the light uniform element and the optical member having the function of condensing, diffusing, and deflecting and separating.

An eleventh aspect of the present invention is a backlight unit comprising a light source and the light uniform element according to any one of the first to ninth aspects.
The invention of claim 12 is a backlight unit comprising a light source and the optical sheet of claim 10.

  The invention of claim 13 is 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 claim 11 or 12. To do.

  According to the present invention, by using a light uniform element having a structure in which a light deflection element is provided on one side of a base material surface composed of a light propagation layer and a diffusion base material and unevenness is provided on the opposite surface, the distance from the light source It is possible to emit uniform light without uneven brightness on the screen display side even for configurations where the distance between light sources is close or where the interval between light sources is widened, and by changing the thickness and material of each layer in a multilayer configuration, It is possible to provide a light uniform element capable of preventing warpage due to heat emitted from a light source. An optical sheet having a configuration in which a light uniform element and an 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 backlight including the optical sheet Units and display devices can be provided.

It is a cross-sectional schematic diagram which shows an example of the display apparatus which comprises the light uniform element concerning this invention, an optical sheet, and a backlight unit. It is explanatory drawing for demonstrating the function of the light uniform element in embodiment of this invention. It is explanatory drawing for demonstrating the structure of the light-diffusion unit lens in embodiment of this invention. (A) is explanatory drawing which shows an example of the light-diffusion unit lens which comprises the light deflection | deviation element of this invention, (b) is description which shows the other example of the light-diffusion unit lens which comprises the light deflection | deviation element of this invention. FIG. It is explanatory drawing for demonstrating the function at the time of carrying out the dispersion | distribution mixing | blending of the diffusing material in the light uniform element in embodiment of this invention. (A) is a schematic diagram showing an embodiment when the light uniform element of the present invention is integrally molded, and (b) is a schematic diagram showing an embodiment when the light deflection element of the present invention is molded into a sheet shape. FIG. It is a schematic diagram which shows an example at the time of providing the optical film for light diffusion in the light emission surface side of the light uniform element concerning this invention. It is a figure which shows the evaluation result of the Example and comparative example of this invention in effect this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6. 1 to 6 show the configuration of the light uniform element, the optical sheet, the backlight unit, and the display device according to the present embodiment and their usage, and the scale or ratio of each part does not match the actual one. . Moreover, it is not limited to this.

As shown in FIG. 1, the display device 70 according to the present embodiment includes an image display element 35 and a backlight unit 55.
The image display element 35 includes a liquid crystal panel 32 and deflecting plates 31 and 33 provided on the front and back surfaces of the liquid crystal panel 32, respectively.
The backlight unit 55 includes a plurality of light sources 41 disposed in the lamp house 43 that also serves as a reflector, a light uniform element 25 disposed above the light source 41 (observer side direction F), and the light uniform. It is comprised from the single or several optical member 2 arrange | positioned above the element 25. FIG.
The light H emitted from the light source 41 is diffused by the light uniform element 25, diffused / reflected / condensed / color-shifted by the single or plural optical members 2 disposed above, and displayed as light K as an image display. The light enters the element 35 and is emitted to the observer side F.
The optical member 2 has a function of condensing or diffusing light, reflecting or deflecting light. One or more optical members 2 having such a function are arranged on the light exit surface side of the light uniform element 25, that is, on the light exit surface 26 b side of the light diffusion layer 26. Optical members having different functions are used as the optical member 2 used when a plurality of layers are arranged.

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 reflector 43 is disposed on the opposite side of the plurality of light sources 41 from the observer side F, and reflects light emitted in the direction opposite to the observer side F out of light emitted from the light sources 41 in all directions. And can be emitted to the observer side F. As a result, the light H emitted to the observer side F becomes light emitted almost from the light source 41 in all directions.
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 in the present embodiment is provided with a light deflection element 28 that deflects and emits incident light, and a light exit surface 28 a of the light deflection element 28 that is aligned with the light exit surface 23 a. A light propagation layer 23 that propagates the emitted light and a light diffusion layer 26 that is provided on the light emission surface 23b of the light propagation layer 23 and diffuses the light emitted from the light propagation layer 23 are provided.
The light deflection element 28 is disposed 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, emits the light H to the light propagation layer 23, and emits light from the light propagation layer 23. The diffused light is emitted from the surface 23b.
The light diffusion layer 26 is disposed on the light emission surface 23 b opposite to the light source side of the light propagation layer 23 by overlapping the light incident surface 26 a.
The light deflection element 28 is made of the same material as the base material 281 arranged on the surface of the base material 281 made of a light-transmitting resin and a constant pitch P in the plane direction on the surface of the base material 281 on the light source 41 side. And a plurality of light diffusion unit lenses 28b. A fixed gap 28c is provided between the light diffusion unit lenses 28b adjacent to each other.
Such a light uniform element 25 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. 2 illustrates the function of the light uniform element 25 according to the embodiment of the present invention. Light sources 41 are arranged in a lamp house (reflecting plate) 43 at a constant pitch in the Ve direction (vertical direction of the screen). ing.
The light H emitted from the light source 41 enters the light diffusion unit lens 28 b from the light incident surface of the light deflection element 28 of the light uniform element 25, and the surface of the light uniform element 25 on the viewer side F, that is, the light diffusion layer 26. The light exits from the light exit surface 26b which is the observer side F to the observer side F. When the light diffusing performance of the light uniform element 25 is low, on the light exit surface 26b of the light diffusing layer 26, a region located directly above the light source 41 appears bright and a region located directly above the light source 41 appears dark. It is visually recognized as luminance unevenness (light source image).
On the other hand, when the diffusion performance by the light uniform element 25 is too strong, the region located directly above the light source 41 is dark, and the region located directly above the light source 41 becomes bright, which is also visually recognized as luminance unevenness. .

In the light uniform element 25 in the present embodiment, the light deflection elements 28 are arranged on the surface opposite to the observer side F, and the light diffusion unit lenses 28b of the light deflection elements 28 are two-dimensional at the lens pitch P. A planar gap 28c is provided between the light diffusion unit lenses 28b and the light diffusion unit lenses 28b that are arranged and adjacent to each other.
As shown in FIG. 2, the light H incident on the light deflecting element 28 is separated into a light beam H1 diffused by the light diffusion unit lens 28b and a light beam H2 that goes straight through the gap 28c or is refracted to the light source side. can do. Both light beams that have traveled straight are incident from the light incident surface 26 a of the light diffusion layer 26, diffused inside the light diffusion layer 26, and emitted from the light emission surface 26 b of the light diffusion layer 26 to the viewer side. In this case, by appropriately controlling the ratio of the light beam H to the diffused light H1 and straight or refracted light H2, it is possible to improve the luminance unevenness and to emit a uniform light beam in the plane to the observer. It is.

The pitch P of the light diffusion unit lens 28b of the light deflection element 28 is defined as a distance between two points joined to the light propagation layer 23 when the light diffusion unit lens 28b is viewed in cross section.
The pitch P of the light diffusing unit lenses 28b is desirably 30 μm or more and 300 μm or less. This is because when the pitch P of the light diffusing unit lenses 28b 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 diffusion unit lenses 28b exceeds 300 μm, there is no problem in performance, but the deflection effect of the light deflection element cannot be fully utilized unless the thickness of the light propagation layer 23 is increased. In using the light uniform element 25 as an optical member, the total thickness is preferably thin, and the pitch P is preferably 300 μm or less.

The light diffusion unit lens 28b constituting the light deflection element 28 has the purpose of changing the incident light H to the diffused light H1 to brighten the upper region between the light source 41 and the light source 41. Such a configuration is used. Then, a decrease in luminance in the region located directly above the light source can be considered. However, by providing the light deflection element 28 with a flat gap 28c and using the deflection H2, it is possible to prevent a decrease in luminance in a region located directly above the light source. Further, the distance of the gap is preferably about 3% to 20% of the lens pitch P.
The distance of the gap d is determined according to the relationship between the distance between the light sources and the distance between the light source and the light uniform element. When the distance is less than 3%, the light diffusion unit in which the incident light H exists on both sides is determined. Light rays that are interfered by the lens and incident on the gap 28c are insufficient, and the amount of H2 is insufficient, so that sufficient luminance cannot be obtained in a region located directly above the light source 41.
On the other hand, when the gap 28c exceeds 20%, the brightness of the area located directly above the light source 41 can be sufficiently obtained, but the brightness of the area located directly above the light source 41 becomes relatively low. For this reason, luminance unevenness cannot be improved.
The inter-light source distance refers to the distance between the central portion of the light source 41 and the central portion of the light source 41 located closest to the light source. Further, the distance between the light source and the light uniform element refers to a distance that is the shortest when the center of the light source 41 and the light uniform element 25 are connected by a straight line.

The light diffusing unit lens 28b of the light deflection element 28 has a convex curved surface shape or a triangular prism shape, a first apex portion 28e having an arcuate surface or a ridgeline, and a first inclination extending from the first apex portion 28e to the surface of the gap 28c. The surface 28a has a first skirt portion 28d that terminates the inclination of the first inclined surface 28a and intersects the surface of the gap 28c. The light diffusing unit lens having such a shape is preferably configured so that the cross-sectional area when viewed in a transverse direction decreases from the first skirt portion 28d to the first top portion 28e.
By using such a shape, the diffusion efficiency after the light beam H emitted from the light source 41 enters the light diffusion unit lens 28b increases. By increasing the diffusion efficiency, the light beam reaches a portion located between the light sources and can be brightened, and thus light having a uniform luminance is emitted from the light diffusion layer 26 to the observer side F. It becomes possible to do.

Further, in the light diffusion unit lens 28b, as shown in FIG. 3, a straight line connecting the first apex portion 28e and one first skirt portion 28d where the inclination of the first inclined surface 28a terminates, and the first apex portion The angle θ formed by the straight line connecting 28e and the first first skirt 28d and the opposite first skirt 28d opposite to each other at the end of the inclination of the first inclined surface 28a is 20 ° or more and 70. It is desirable that the temperature is not more than °.
When the light diffusion unit lens 28b having such a shape is used, the diffusion efficiency of the light H emitted from the light source 41 is improved when the light diffusion unit lens 28b diffuses the light beam H. That is, it becomes easy to deliver a light beam to a portion located between the light sources. Further, in the light diffusing unit lens located at a position away from the light source, the effect of starting up the light beam by the total reflection action also occurs. Accordingly, uniform light can be emitted from the light diffusion layer 26 to the observer side F. The angle θ is determined according to the relationship between the light source distance and the light source-light uniform element distance.
When the angle θ is less than 20 °, depending on the angle at which the incident light is incident, total internal reflection occurs a plurality of times inside the light diffusion unit lens 28b, which causes a reduction in overall luminance.
On the other hand, when the angle θ exceeds 70 °, the light diffusion unit lens 28b does not have a sufficient diffusion effect, and it is difficult to brighten the region located directly above the light source.

  Further, as shown in FIG. 4A, the light diffusion unit lens 28b may be a lens group in which a plurality of convex micro lenses 28B1 are continuously arranged in the plane direction. By using such a light diffusion unit lens 28b as a plurality of lens groups, the ratio of the number of light diffusion unit lenses 28b to the gap 28c can be easily set. Specifically, a configuration in which one gap 28c is provided for three fine lenses is possible. With this function, the ratio of the light beam H1 to be diffused and the light beam H2 to be transmitted / refracted can be easily determined, which is effective in reducing luminance unevenness.

  Further, as shown in FIG. 4B, when the light diffusing unit lens 28b is a triangular prism-shaped lens group, the apex angles θ of the lenses in the lens group may be different from each other. . By providing a plurality of lenses having different θ in the lens group, the light deflection element 28 can have a plurality of light diffusion effects. Due to such effects, the diffused light H1 shown in FIG. 2 can be emitted at various angles, the area between the light sources 41 can be evenly brightened, and the light beam H2 passing through the optical currency gap 28c. Thus, the region located directly above the light source 41 can also be brightened. From these results, it is effective to reduce luminance unevenness.

In the light deflection element 28, it is desirable that the light scattering particles are dispersed and blended in the resin layer constituting the light deflection element.
As shown in FIG. By dispersing the light scattering particles in the light deflection element 28, the light H is deflected to H1 and H2 by the light deflection element, and the light is further diffused to emit light of uniform brightness to the observer side F. Can be effectively implemented.

The light deflection element 28 can be formed on the light incident surface 23a, which is the surface 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 diffusing layer 26 and the light propagation layer 23 can be integrally formed as a plate-like member by an extrusion method or the like, and the light deflection element 28 can be UV formed on the light incident surface 23 a of the light propagation layer 23. 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, light deflection is performed on the light incident surface 23a of the light propagation layer 23. Element 28 can be UV molded.
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. 6A, the light deflection element 28 of the present invention and the light uniform element 25 comprising 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. 6B, 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 an adhesive and 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 warp preventing function.
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 warp 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.

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. On the contrary, when 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 diffusion layer 26 is preferably a single diffusion layer and has a haze value of 80% or more and 99% or less. When the haze value is less than 80%, it is difficult to obtain a sufficient diffusion effect, which becomes an obstacle to reduction in luminance unevenness. The thickness of the diffusion layer 26 is desirably 5% or more and 30% or less of the total thickness of the light uniform element 25. If the thickness of the diffusion layer is less than 5%, the diffusion performance is insufficient. On the other hand, if the thickness of the diffusion layer exceeds 30%, the thickness of the spectral propagation layer becomes thin, and the space between the light deflection element 28 and the light diffusion layer 26 becomes narrow, and as a result. As a result, the effect of the light deflecting element 28 is weakened, which is an adverse effect of reducing luminance unevenness.

  The light diffusing 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 is different from that of the light diffusing agent. ing. As the transparent resin, a thermoplastic resin, a thermosetting resin, or the like can be used. For example, styrene resin, polycarbonate resin, methacrylic resin, methyl methacrylate resin, glass, vinyl chloride resin, 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, cyclohexadiene polymer, amorphous polyester resin, amorphous fluorine resin, etc. 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 layer 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 light-diffusion layer 26 can be shape | molded by performing melt extrusion molding or injection molding to the mixture of this transparent resin and light diffusing agent of a molten state.

Further, the light diffusion layer 26 may be provided with an uneven shape on the light exit surface 26b. Typical examples of the method for forming irregularities include extrusion molding, mat processing, embossing, transfer or bonding, etching, and physical blasting such as sandblasting, electrical discharge, and cutting. I can do it. By providing such a concavo-convex shape, the light emitting surface 26b of the light diffusing layer 26 has an effect of scattering the emitted light of the emitted light, which is effective in reducing luminance unevenness.
In addition, by providing an uneven surface, the amount of light reflected from the light exit surface 26b and the air layer on the observer side to the opposite side of the observer side is reduced, and the amount of emitted light is increased. Improvement of brightness can be realized.

As the concavo-convex shape provided on the light exit surface 26b of the light diffusion layer 26, an optical film 21 formed by arranging unit lenses as shown in FIG. 7 is used.
The optical film 21 diffuses the light emitted from the light emission surface 26b of the light diffusion layer 26 and emits it toward the optical member 2 of FIG. 1, and as shown in FIG. And a plurality of light diffusing lenses 212 arranged on the light emission surface of the light transmissive substrate 211 at a constant pitch. The light diffusing lens 212 includes a top portion 21a having a convex curved surface shape and an arcuate surface, and inclined surfaces 21b facing the light-transmitting substrate 211 from both sides of the top portion 21a. The light diffusing lens 212 is configured such that the cross-sectional area when viewed from the light diffusing lens 212 is reduced as it goes from the light transmissive base material 211 to the top portion 21a.
As shown in FIG. 7, the light diffusion lens 212 is not limited to a convex curved surface shape and an arcuate surface, but may be a triangular prism shape, and the shape is not limited.

  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 in the embodiment of the present invention includes the optical uniform element 25 described above and an optical film having a function of condensing or diffusing light, or an optical film having a function of deflecting and separating the light uniform element 25. By using a configuration in which a single optical film or a plurality of optical films having different functions are laminated, the brightness on the observer side F is improved by using the light K with improved condensing and diffusing characteristics, and the viewing angle of the light intensity An image in which the direction distribution is smoothed and the lamp image is reduced can be displayed on the image display element 35.

  In the present invention, the optical member 2 provided on the light exit surface side of the light uniform element 25 has an optical film that collects light to improve luminance, a light diffusion film that diffuses light, and a light separation function. A typical example is a film that uses to improve luminance. 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.

The display device 70 according to the 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 has the light collection / diffusion characteristics obtained by the backlight unit 55 described above. Since the improved light K is used, the luminance on the observer side F can be improved, the light intensity distribution in the viewing angle direction can be smoothed, and an image with a reduced lamp image can be obtained.
Further, 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. The brightness on the observer 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.

Next, examples of the present invention will be described. In addition, this invention is not limited only to these Examples.
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.

(Examples 1-4)
First, the light deflection element 28 was formed by applying a UV curable resin having a refractive index of 1.52 to a PET film having a thickness of 188 μm and patterning it with a mold. As a configuration of the light deflection element, the light diffusion unit lens 28b has a pitch of P = 100 μm, and an angle θ formed by the skirt portion 28e and the top portion 28d is 30 °. A convex cylindrical lens having a curved surface with a top portion of R180 was used, and four types of gaps 28c were produced in the range of 3, 9, 15, and 20 mm.
On the other hand, the light propagation layer 23 and the light diffusion layer 26 were formed by a multilayer extrusion method with a total thickness of 2 mm. At this time, the light propagation layer was made of transparent polystyrene (PS), and the diffusion layer was made by dispersing and blending light scattering particles in the transparent PS at a weight ratio of 15%. Further, the light propagation layer was formed to have a thickness of 1.8 mm, and the light diffusion layer was formed to have a thickness of 0.2 mm.
Finally, the light uniform element 25 was produced by bonding the PET film side of the light deflection element to the light propagation layer side formed by the multilayer extrusion via an adhesive selected as the fixing material 20.

(Examples 5 to 8)
The light deflection element 25 was manufactured by a method similar to that of the first to fourth embodiments, except for the structure of the light diffusing element 28. As a light diffusion unit lens 28b, P = 100 μm, θ is 60 °, a convex cylindrical lens having a curved surface in which the skirt and the top are R180, and the gap 28c is 3, 9, 15, 20 mm. 4 types were produced.

(Examples 9 to 12)
The light deflection element 28, the light propagation layer 23, and the light diffusion layer 28 were simultaneously extruded by multilayer extrusion to form the light uniform element 25. Specifically, the light diffusion layer 26 has a structure in which light scattering particles are dispersed and blended in a transparent PS resin at a weight ratio of 14%, and the thickness is 0.3 mm. The light propagation layer is made of a transparent PS resin and has a thickness of 1.5 mm. The light deflecting element 28 has a constitution in which light scattering particles are dispersed and mixed in PS resin, the shape is such that the light diffusion unit lens 28b has P = 100 μm, the θ is 30 °, and the skirt and top portions Is a convex cylindrical lens having a curved surface, and the gap 28c is set to 3, 9, 15, 20 mm. Thus, four types of light uniform elements were produced.

Next, a comparative example will be described.
(Comparative Example 1)
As Comparative Example 1, the light deflection element 28 is manufactured by the same method as in Example 1, the light diffusion unit lens 28b has a pitch of P = 100 μm, and the angle formed by the skirt 28e and the top 28d is 30 °. Thus, a convex cylindrical lens having a curved surface at the bottom and the top was prepared without providing the gap 28c.
On the other hand, the light propagation layer 23 and the light diffusion layer 26 are produced by the same method as in the first embodiment, and the light uniform element 25 is also connected to the light propagation layer and the light deflection element via the fixed layer as in the first embodiment. It was made by bonding.

(Comparative Example 2)
As Comparative Example 2, the light deflection element 28 is manufactured by the same method as in Example 1, the light diffusion unit lens 28b has a pitch P = 100 μm, and the angle θ formed by the skirt 28e and the top 28d is 60. Further, a convex cylindrical lens having a curved surface at the skirt and the top was prepared, and the gap 28c was 30 μm.
On the other hand, the light propagation layer 23 and the light diffusion layer 26 are produced by the same method as in the first embodiment, and the light uniform element 25 is also connected to the light propagation layer and the light deflection element via the fixed layer as in the first embodiment. To be joined.

(Comparative Examples 3 and 4)
As Comparative Examples 3 and 4, the light deflection element 28 is manufactured by the same method as in Example 1, the light diffusion unit lens 28b is a 90 degree prism with a pitch P = 100 μm, and the gap 28c is manufactured in two types of 8 and 13 μm. did.
On the other hand, the light propagation layer 23 and the light diffusion layer 26 are produced by the same method as in the first embodiment, and the light uniform element 25 is also connected to the light propagation layer and the light deflection element via the fixed layer as in the first embodiment. It was made by bonding.

(Comparative Example 5)
The light deflection element 28, the light propagation layer 23, and the light diffusion layer 28 were simultaneously extruded by multilayer extrusion to form the light uniform element 25. Specifically, the light diffusion layer 26 has a structure in which light scattering particles are dispersed and blended in a transparent PS resin at a weight ratio of 14%, and the thickness is 0.2 mm. The light propagation layer is made of a transparent PS resin and has a thickness of 1.5 mm. The light deflecting element 28 has a constitution in which light scattering particles are dispersed and mixed in PS resin, the shape is such that the light diffusion unit lens 28b has P = 100 μm, the θ is 30 °, and the skirt and top portions Is a convex cylindrical lens having a curved surface, and the gap 28c was set to 0 mm.

  On the surface of the observer side F of the light uniform element 25 of Examples 1 to 12 and Comparative Examples 1 to 5 prepared as described above, a configuration was prepared in which a diffusion film, a 90-degree triangular prism sheet, and a diffusion film were stacked in this order. . 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.

Next, optical evaluation will be described.
(Optical evaluation)
The display devices of this example and comparative example were evaluated by the following measurement 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. In addition, since the waveform distribution corresponding to the cold cathode tubes is obtained, the luminance distribution is obtained by extracting the luminance data corresponding to the five cold cathode tubes at the center and calculating the average luminance, so that the light rays of the optical sheet are obtained. It was determined that the diffusibility was good.
The measurement result of a present Example and a comparative example is shown in FIG.

In Examples 1 to 4, the evaluation results were good, and no luminance unevenness was confirmed. In Comparative Example 1 compared with these, the luminance of the region located directly above the light source 41 was significantly lower than the luminance of the intermediate portion between the light sources 41, and was recognized as luminance unevenness.
In Examples 5 to 8, the evaluation results were good, and no luminance unevenness was confirmed. In Comparative Example 2 compared with these, the luminance immediately above the light source 41 was significantly higher than the luminance of the intermediate portion of the light source 41, and was recognized as luminance unevenness.

  Examples 9 to 12 are examples in which light scattering particles are dispersed and blended in the light deflection element 28, but the degree of freedom of the combination of θ and the gap 28c that defines the shape of the light diffusion unit lens by blending the light scattering particles. Is effective in eliminating uneven brightness. However, even if light scattering particles are blended in the light deflection element, if θ defining the shape of the light diffusing unit lens is small as in Comparative Example 5, it is difficult to eliminate luminance unevenness when there is no gap. It was.

  H, H1, H2, K ... light, P ... light deflection element pitch, F, F '...... observer side, X ... planar view direction, Ve ... image display device vertical direction, Ho ... image display Horizontal direction of the apparatus, 2... Optical member, 20... Fixed part, 21... Optical film, 211 .. light transmissive substrate, 212. ...... Light propagation layer, 23a. Light incident surface of light propagation layer, 23b. Light emission surface of light diffusion layer, 26. Light diffusion layer, 26a. Light incidence surface of light diffusion layer, 26b. Light exit surface of diffusion layer, 25... Light uniform element, 28... Light deflection element, 28 a... Light entrance surface of light deflection element, 28 b... Light diffusion unit lens, 28 c. Hem of unit lens, 28e: top of light diffusing unit lens, 281: base material, θ: fixed to light diffusing unit lens Defined angle, 31, 33 ... Deflection plate, 32 ... Liquid crystal panel, 35 ... Image display element, 41 ... Light source, 43 ... Lamp house, 52 ... Optical sheet, 55 ... Backlight unit, 70: Display device.

Claims (13)

A light deflection element that deflects and emits incident light;
A light propagation layer that is provided on a light exit surface of the light deflection element and propagates light emitted from the light deflection element;
A light diffusion layer that is provided on a light emission surface of the light propagation layer and diffuses light emitted from the light propagation layer;
When light passes through the light deflection element, the light propagation layer, and the light diffusion layer and is emitted from the light emission surface of the light diffusion layer, the luminance on the surface parallel to the light emission surface is made uniform. A light uniform element,
The light deflecting elements include a light-transmitting base material constituting a light exit surface side of the light deflecting element, and a plurality of light deflecting elements arranged at a constant pitch with a constant gap on the light incident surface side of the base material Comprising a light diffusing unit lens,
The gap is not less than 3% and not more than 20% of the pitch of the light diffusion unit lens.
An optical uniform element characterized by the above.   The light uniform element according to claim 1, wherein a surface of the gap is flat.   The ratio of the thickness of the light diffusion layer to the sum of the thickness of the light diffusion layer and the thickness of the light propagation layer is 5% or more and 30% or less. Light uniform element.   The light diffusing unit lens has a top portion, an inclined surface that faces the surface of the gap from both sides of the top portion, and a skirt where the inclined surface intersects the surface of the gap, and the light diffusing unit lens is viewed in a transverse view. 4. The light uniform element according to claim 1, wherein a cross-sectional area in such a case is configured to decrease from the skirt to the top. 5.   An angle θ formed by a straight line connecting the top and the one skirt and a straight line connecting the top and the other skirt is 20 ° or more and 70 ° or less, The light uniform element according to claim 4.   4. The light uniform element according to claim 1, wherein each of the light diffusing unit lenses includes a lens group in which a plurality of fine convex lenses are arranged at a constant pitch. 5.   The light uniform element according to any one of claims 1 to 6, wherein light scattering particles are dispersed and blended inside the base material and inside the light diffusion unit lens.   The light uniform element according to claim 1, wherein the light deflection element, the light propagation layer, and the light diffusion layer are integrally formed by a multilayer extrusion method. An optical film for diffusing light emitted from the light exit surface is provided on the light exit surface of the light diffusion layer,
The optical film has a constant pitch on the surface of the light transmissive substrate disposed on the light emitting surface side of the light diffusing layer and the surface of the light transmissive substrate opposite to the light emitting surface of the light diffusing layer. The light diffusing lens has a top portion, and an inclined surface that faces each of the light transmitting bases from both sides of the top portion, and the light diffusing lens is the light diffusing lens. 9. The light uniform element according to claim 1, wherein a cross-sectional area in a cross-sectional view is configured to decrease from the light transmitting base toward the top. The light uniform element according to any one of claims 1 to 9,
A single or a plurality of optical members disposed on the light exit surface side of the light uniform element and having a function of collecting, diffusing, reflecting, or deflecting and separating light.
An optical sheet characterized by that. A light source;
The optical uniform element according to any one of claims 1 to 9,
Backlight unit characterized by that. A light source;
An optical sheet according to claim 10.
Backlight unit characterized by that. An image display element that transmits / shields light in pixel units and displays an image;
The backlight unit according to claim 11 or 12,
A display device.

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