JP4321659B1 - Optical device, optical uniform device, optical sheet, backlight unit and display device - Google Patents

Abstract

A lamp image can be erased by uniformly emitting incident light from a plurality of light sources, and even if the distance between the light source and the light device or the light uniform device is reduced, heat generated from the light source is used. Provided are an optical device, a light uniform device, an optical sheet, a backlight unit, and a display device that do not warp.
An optical device comprising a light propagation layer and a light deflecting element, or a light uniform device having a diffusion substrate integrated with a light exit surface of a light propagation layer of the optical device is provided on a display device. An optical device or an optical deflection element of an optical uniform device is disposed on the light source side, and an optical member 2 or the like is disposed on the light propagation layer of the optical device or the diffusion base of the optical uniform device if necessary. Display device.
[Selection] Figure 1

Description

  The present invention relates to an optical device, a light uniform device, an optical sheet, a backlight unit, and a display device used for illumination light path control. In particular, the present invention relates to an optical device, an optical uniform device, an optical sheet, a backlight unit, and a display device that are used for illumination light path control in an image display apparatus typified by a flat panel display.

In recent large-sized liquid crystal televisions, direct type backlights in which a plurality of cold cathode tubes and LEDs (Light Emitting Diodes) are arranged are employed.
A resin plate having a strong light scattering property is used between the image display element and the light source so that a cold cathode tube or an LED as a light source is not visually recognized.
The diffusing plate diffuses light in all directions by the light diffusing effect, and thus darkens the liquid crystal display device. In addition, the thickness of the diffusion plate usually requires a thickness of about 1 to 5 mm in order to increase the light scattering property and to support the optical film formed on the diffusion plate. The plate absorbs light not a little, and the liquid crystal display becomes dark.

  Moreover, since the liquid crystal television tends to be thinner year by year, the diffusion plate also tends to be thinner, and further improvement in diffusibility is demanded.

Conventionally, a diffusion plate used in a direct type backlight is intended to diffuse light emitted from a cold cathode tube, which is a light source, and reduce luminance unevenness (lamp image). However, it is difficult to completely erase the lamp image.

If the number of diffusing particles is forcibly increased in order to completely eliminate the lamp image, the total light transmittance is lowered too much, causing a decrease in luminance.
Further, if the diffusion particles of the diffusion plate are reduced so as not to reduce the total light transmittance, the diffusion effect is also lowered.

Patent Documents 1 to 3 disclose examples in which a lens shape is formed on the exit surface of a diffusion plate as means for improving diffusion performance. For example, a lens having a convex curved surface is disposed 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 may complicate the manufacturing process. Further, by shaping the lens shape on the exit surface of the diffuser plate, the total light transmittance of the diffuser plate may be lowered, and the liquid crystal display screen may be darkened. Furthermore, moire interference fringes may be generated from the lens sheet and the liquid crystal pixels arranged on the diffusion plate.

As a means for improving the brightness of the liquid crystal display screen, a brightness enhancement film (BEF), which is a registered trademark of 3M USA, is widely used as a lens sheet.
FIG. 17 is a schematic cross-sectional view showing an example of the BEF arrangement, and FIG. 18 is a perspective view of the BEF. As shown in FIGS. 17 and 18, the BEF 185 is an optical film in which unit prisms 187 having a triangular cross section are periodically arranged in one direction on a member 186. The unit prism 187 has a size (pitch) larger than the wavelength of light.

  The BEF 185 collects light from “off-axis” and redirects this light “on-axis” or “recycle” toward the viewer. can do. That is, the BEF 185 can increase the on-axis luminance by reducing the off-axis luminance when the display is used (observation). Here, “on the axis” means a direction that coincides with the viewing direction F ′ of the viewer, and is generally on the normal direction side with respect to the display screen.

However, when the BEF 185 is used, the light component due to the reflection / refraction action may be unnecessarily emitted in the lateral direction without proceeding to the viewer's visual direction F ′.
The line B in FIG. 19 shows the characteristics of the BEF 185. The light intensity is highest at an angle of 0 ° (corresponding to the axial direction) with respect to the light intensity and the viewing direction F ′, but the angle with respect to F ′ is ± 90. Near the angle, a small light intensity peak (side lobe) is generated, and the amount of light emitted from the lateral direction is increasing.

  When a lens sheet represented by BEF185 is used, a diffusion film (hereinafter referred to as a lower diffusion film) in which a diffusion filler is applied on a transparent substrate and has both diffusion and condensing functions is used as a diffusion plate and a lens sheet. The diffused light emitted from the diffuser plate can be efficiently collected, and the visibility of the light source that cannot be erased only by the diffuser plate can be suppressed.

Furthermore, when a light diffusing film is disposed between the lens sheet and the liquid crystal panel, side lobes can be reduced and moire interference occurs between the regularly arranged lenses and the liquid crystal pixels. Stripes can be prevented.
However, the method using the lower diffusing film and the light diffusing film increases the number of members, which complicates the work for assembling the display, and causes problems such as contamination between optical sheets.

  In Patent Document 4, as a means for solving such a problem, an optical film from only the unit prism is not used, but an array structure in which unit lenses are arranged at a constant pitch in a two-dimensional direction. A backlight unit using an optical film is disclosed. The optical characteristics of this optical film are shown by line A in FIG. 19, side lobes are not shown, and the light intensity in the viewing direction F ′ is also improved over line B.

However, in the backlight unit using such an optical film, it is necessary to flatten the exit surface of the diffuser plate in order to integrally laminate the optical film, so a lens is formed on the exit surface of the diffuser plate. It was difficult to increase the diffusion effect and the light collection effect.
JP 2007-103321 A JP 2007-12517 A JP 2006-195276 A JP 2007-213035 A

The present invention has been made in view of the above problems, and can uniformly reduce / extinguish a lamp image by emitting incident light from a plurality of light sources uniformly, and a light source, an optical device, and An object of the present invention is to provide an optical device that prevents warpage due to heat generated from a light source even when the distance from the optical uniform device is short, and an optical uniform device.
Further, an optical film that improves the luminance toward the viewer side by efficiently emitting the light emitted from the optical device and the light uniform device to the viewer side is integrated with the light device and the light uniform device. An object is to provide a laminated optical sheet, a backlight unit including the optical sheet, and a display device.

In order to achieve the above object, the present invention employs the following configuration. That is, the invention of claim 1 is a linear light source,
A light deflection lens whose lens shape is a lenticular type, and an angle formed by a major axis direction of the lenticular lens and a major axis direction of the linear light source when viewed in plan is 20 degrees or less;
A light propagation layer disposed on a light exit surface side of the light deflection lens, on which light deflected by the light deflection lens is incident;
A light diffusing substrate on the light exit surface side of the light propagation layer;
A light uniform device comprising:
The light deflection lens includes a first apex portion and a first inclined portion that extends from the first apex portion to a surface on the linear light source side of the light propagation layer, and the first apex portion is compared with the first inclined portion. Consisting of arcs or ridges with a small radius of curvature,
And the refractive index of the light propagation layer is n, the pitch of the light deflection lens is P, and the tangent to the first inclined surface at the junction where the first inclined surface is bonded to the light propagation layer is When the angle between the surface of the light propagation layer and the linear light source side is θ,
A light uniform device in which the thickness T of the light propagation layer satisfies the following formula 1;
A liquid crystal display device having

The invention of claim 2 is characterized in that the light uniform device is:
A light diffusing region dispersed in a transparent resin, the light diffusing base material having a total light transmittance of 30% to 80% and a haze value of 95% or more;
The light propagation layer having a total light transmittance of 80% or more and a haze value of 95% or less;
The liquid crystal display device according to claim 1, further comprising:

The invention according to claim 3 is a shape in which the first inclined portion has a curved first curved inclined portion, a tangent at each point of the first curved inclined portion, and the light source side of the light propagation layer 2. The liquid crystal display device according to claim 1, wherein an angle formed with the surface of the liquid crystal continuously changes between 20 degrees and 90 degrees.

  According to the above configuration, it is possible to emit uniform light even when the distance to the light source is close, and by changing the thickness and material of each layer in a multilayer configuration, warpage due to heat emitted from the light source can be prevented. An optical device that can be used, and an optical uniform device can be provided. Also, the optical film that improves the luminance on the viewer side by efficiently emitting the light emitted from the optical device and the light uniform device to the viewer side, and the optical device and the light uniform device are integrated. A laminated optical sheet, a backlight unit including the optical sheet, and a display device can be provided.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is a schematic cross-sectional view illustrating an example of an optical device, a light uniform device, 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 device, the light uniform device 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 device 25, diffused / reflected / condensed / color-shifted by one or a plurality of optical members disposed thereon, and emitted from the backlight unit 55. The incident 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 use 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 optical device 24 according to the embodiment of the present invention includes a light deflection element 28 and a light propagation layer 23. The light deflection element 28 is arranged toward the light source 41 side of the display device 70. The function of the optical device 24 is to deflect the light H incident from the incident surface of the light deflecting element 28, emit it to the light propagation layer 23, and emit diffused light from the light emission surface of the light propagation layer 23. In addition, the light uniform device 25 has the diffusion base material 26 in the optical device 24 described above, and the surface 26a opposite to the observer side F of the diffusion base material 26 is on the viewer side F of the light propagation layer 23. The surface 23b is formed to overlap.
The optical device 24 and the light uniform device 25 as described above are not limited to liquid crystal devices, but may be any devices that perform optical path control, such as rear projection screens, solar cells, organic or inorganic EL, and lighting devices. Can also be used.

FIG. 2A is a diagram illustrating the function of the light uniform device 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 opposite to the viewer side F of the light uniform device 25, that is, the light deflection element 28, and the surface on the viewer side F of the light uniform device 25, that is, the diffusion base material 26. From the surface 26b on the observer side F to the observer side F.
When the light uniform device 25 has insufficient diffusion performance, the surface 26b on the viewer side F of the diffusion base material 26 has a bright area facing the light source 41 and a dark area facing the light source 41. Visible and visually recognized as luminance unevenness (light source image).
In the light uniform device 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. The strong front light H incident from the light source 41 is deflected in the light deflection element 28 in the traveling direction, the incident light deflected in the light propagation layer 23 is spread, diffused in the diffusion base material 26, and uniform light is observed. It injects to person side F.

すなわち、図２（ｂ）に示されるように、光伝搬層２３の厚みＴは、光偏向要素２８の第一傾斜面２８ｂが光伝搬層２３と接合する点３０に入射した光が、角度θの面で偏向され、光伝搬層２３内にてＶｅ方向に光偏向要素２８のピッチＰ以上拡がるために必要な厚みと定義される。 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 element 28 is joined to the light propagation layer 23 and a surface 23a opposite to the observer side F of the light propagation layer 23 are formed. When the angle is θ, the pitch of the unit lens of the light deflection element 28 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 element 28 is joined to the light propagation layer 23 is angle θ. Is defined as the thickness required to expand the light deflection element 28 in the direction Ve by the pitch P or more in the light propagation layer 23.

  Here, the pitch P of the unit lenses of the light deflection element 28 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. In addition, it is desirable that the pitch P of the light deflection elements 28 in which the numerical formula 1 is effective is 10 μm or more and 300 μm or less. This is because when the pitch P of the light deflection elements 28 is smaller than 10 μm, the structure period approaches the wavelength, and the influence of diffraction cannot be ignored. When the pitch P of the light deflection elements 28 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.

  That is, the front light H incident on the light deflection elements 28 arranged at a constant pitch is deflected by the light deflection elements 28, and the light deflected by the adjacent light deflection elements 28 is mixed in the light propagation layer 23, Diffusion by the diffusion base material 26 and injection 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 diffusion base material 26 without being mixed, so that the diffusion performance of the light uniform device 25 is insufficient.

図２（ｃ）に示されるように、２つ隣の光偏向要素２８によって偏向された光が光伝搬層２３内で混ざり合う厚さＴであれば、その拡散性能は更に増すため、光源４１との距離が１０ｍｍ以下と近づいても、ランプイメージを低減／消滅することが可能となる。 Furthermore, it is more preferable that the light deflected by the two adjacent light deflection elements 28 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 deflected by the two adjacent light deflecting elements 28 has a thickness T at which the light is mixed in the light propagation layer 23, the diffusion performance is further increased. The lamp image can be reduced / disappeared even when the distance to the lamp approaches 10 mm or less.

As the light deflection element 28, 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 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.
Furthermore, the light deflection element 28 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 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 element 28 can be used by combining a plurality of the 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.

  The light deflection element 28 may include a light cover layer that diffuses and reflects the light H from the light source 41 on the first top portion 28a.

FIG. 4A is a diagram showing the light reflection effect of the light cover layer 28c. For example, by forming the light cover layer 28c on the first apex portion 28a of the convex curved lens, it is possible to select only a region having a large deflection angle by reflecting light incident on a region having a small deflection angle in the light deflection element 28. , Can improve the diffusion performance. At this time, the angle formed between the tangent line at each point of the first inclined surface 28b and the surface 23b opposite to the observer side of the light propagation layer 23 is 20 degrees to 90 degrees, and the tangent line at each point of the first apex portion 28a. It is further desirable that the angle formed by the observer side F and the opposite surface 23a of the light propagation layer 23 is in the range of 0 degrees to 40 degrees.
FIG. 4B is a diagram showing the light diffusion effect of the light cover layer 28c. For example, by forming the light cover layer 28c on the first apex portion 28a of the convex curved lens, the diffusion performance can be improved by diffusing the light incident on the region where the deflection angle of the light deflection element 28 is small.
FIG. 5A shows a case where the light cover layer 28c is formed on the first apex portion 28a of the convex curved lens. The light cover layer 28c may be formed in a rounded shape, along the curved first apex portion 28a.

  In order to facilitate the formation of the light cover layer 28c on the first top portion 28a, the first top portion 28a may be a substantially flat surface as shown in FIG. 5B, for example. Further, as shown in FIG. 5C, the light cover layer 28c may be formed after the first apex portion 28a is formed in a convex shape. The light cover layer 28c may partially wrap around the first inclined surface 28b as shown in FIG. However, if most of the first inclined surface 28b is covered, the diffusing function of the light deflection element 28 is lowered. Therefore, the wraparound amount Δ is 30% or less with respect to the width p1 of the first inclined surface 28b. desirable. Here, an example is given in which the light cover layer 28c is formed on the first apex portion 28a of the convex curved lens. However, the present invention is not limited to this, and it is formed on the first apex portion 28a such as the triangular prism shape, the curved triangular prism shape, or the combination lens shape described above. This includes cases where

Here, examples of the light cover layer 28c include a light diffusion / reflection layer made of a white pigment. Here, examples of the white pigment include titanium oxide, aluminum oxide, barium sulfate, and the like, which are formed by coating or printing. Furthermore, a metal thin film or the like can be formed by a vapor deposition method, a pressure bonding method, or the like.

Furthermore, the light cover layer 28c may contain a fluorescent material. The light H emitted from the light source 41 includes ultraviolet light although a trace amount. Therefore, for example, in the configuration of the backlight set in the order of the diffusing plate, the prism sheet, and the diffusing film on the light source 41 (that is, showing the direction of the viewer side F), Contains a UV absorber. In the present configuration, the light cover layer 28 c is formed on the first top portion 28 a of the light deflection element 28, and thus is disposed at a position closest to the light source 41. Therefore, the amount of light of the entire backlight can be increased by efficiently using the ultraviolet light by causing the fluorescent material to emit light by the ultraviolet light contained in the light source 41. Further, the ultraviolet light incident from the first inclined surface 28b is absorbed by the UV absorber contained in any one of the light deflecting element 28, the light propagation layer 23, and the diffusion base material 26, so that the ultraviolet light is incident on the viewer side F. Light does not leak. As the fluorescent material, any material can be used as long as it is generally used for optical applications, for example, a white LED.

The light deflection element 28 may have a concave lens shape as shown in FIG. 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 diffusion base material 26. Therefore, the thickness of the optical device 24 and the optical uniform device 25 can be reduced as compared with the convex lens shape, which is desirable.
Further, as shown in FIG. 6B, 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 lens 28.
Furthermore, as shown in FIG. 6C, 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. 6D, 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 inkjet, water repellency / oil generation treatment, and the like.

The light deflection element 28 may be arranged by appropriately combining a plurality of the above-described lenses. Alternatively, as shown in FIG. 8A and FIG. 8B, the pitch P and height of the unit lenses may be changed and arranged. As a result, the farthest intersection α of the light deflection element 28 is unevenly arranged in the light propagation layer 23. FIG. 8C shows a configuration in which the farthest intersection point α is arranged in parallel and on a straight line with respect to the arrangement direction of the unit lenses of the light deflection element 28. When the front light H is incident on the light deflection element 28, a condensing point is generated on the center line of the unit lens, 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. FIGS. 8A to 8C show an example in which the farthest intersection point α is a point where light incident on both ends of the unit lens is deflected and intersects.
In FIG. 8C, for example, when all the light deflection elements 28 have the same shape, the position of the farthest intersection α of the light incident on each light deflection element 28 exists on the same plane. Therefore, since the light H incident from the incident surfaces of the optical device 24 and the light uniform device 25 can obtain the same diffusion performance in any region, the optical device 24 and the light uniform device 25 without unevenness can be provided. . However, as shown in FIGS. 8A and 8B, when the lens shape of the light deflection element 28 is not constant, the farthest intersection α of the light incident on each light deflection element 28 is the same. It does not exist on the surface. Therefore, the thickness T of the light propagation layer 23 is different for each light deflection element 28. 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 elements 28 arranged can satisfy the above-described Expressions 1 and 2, and thus a diffusion effect can be obtained with certainty. For example, when the light source 41 is extremely close to the optical device 24 and the light uniform device 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 element It is effective to make the 28 farthest intersections α non-uniform. In particular, when a plurality of combinations are used, 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 arrange the light deflection element 28 in the region directly above the light source 41 so that the thickness T of the light propagation layer 23 can be set to be the thinnest. 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.

  Although the pitch P of the light deflection element 28 can be determined as appropriate, the larger the pitch P of the light deflection element 28 is, the thicker the thickness T of the light propagation layer 23 is. Therefore, actually, the thickness T is 10 μm or more and 300 μm or less, preferably 10 μm or more. It is calculated | required that it is 200 micrometers 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 diffusion base material 26 and the light propagation layer 23 are integrally formed as a plate-like member by an extrusion method or the like, and the light deflection element 28 is UV-molded on the surface 23a opposite to the observer side F of the light propagation layer 23. 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 propagation layer 23 is integrated with the diffusion base material 26, on 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.

  The light deflecting element 28 is made of 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 molding method or a hot 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 optical device 24 of the present invention can be produced by extrusion. Further, as shown in FIG. 10A, the optical device 24 and the diffusion base material 26 may be integrally formed by multilayer extrusion or the like. On the other hand, as shown in FIG. 10B, after forming 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 diffusion base material 26, it is possible to prevent the optical uniform device 25 itself from warping. Furthermore, the warping of the light uniform device 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 diffusion base material 26. it can.

  The thickness of the light deflection element 28 formed into a sheet shape is preferably 10 μm to 1 mm. Furthermore, it is desirable that it is 25 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 diffusion base material 26.

  The surface of the light deflection element 28 may have finer irregularities. The fine unevenness can further enhance the deflection effect by the light deflection lens 28. 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, and the concavo-convex structure exceeding 10 μm itself becomes the light deflection element 28. As a method for forming fine irregularities, for example, the method of roughening the surface of the light deflection element 28 or the molding die by etching or sandblasting, or the molding die of the light deflection element 28 is further refined. A method such as cutting is used.

  Further, the light deflection element 28 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 incident light H is deflected by the light deflection element 28, the light deflected by the light propagation layer 23 is expanded, and further diffused by the diffusion base material 26, thereby improving the diffusion performance.

  The light propagation layer 23 constituting the light uniform device 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 by the light deflection lens 28 effectively, and causes the incident light to enter the diffusion base material 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.

  More preferably, the light propagation layer 23 does not include a light diffusing element. This is because when the light diffusing element is not contained in the light propagation layer 23, the light deflected by the light deflecting element 28 can be effectively spread and propagated.

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 diffusion base material 26 side is n2, and the refractive index of the light deflection element 28 is n0, Expression 3 is satisfied. desirable.

Formula 3 will be described with reference to FIG.
When the light H enters the light deflection element 28, the light H is deflected by the refractive index of air and the refractive index n0 of the light deflection lens 28. At this time, the larger the refractive index n0 of the light deflection element 28, the larger the refraction angle. Therefore, it is desirable that the refractive index n0 of the light deflection element 28 is larger.
In FIG. 11A, light is emitted from 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 diffusion base material 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 diffusion base material 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 and the refractive index n2 of the layer 23B on the diffusion base material 26 side of the light propagation layer 23 are equal or the light deflection element 28 of the light propagation layer 23. 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 diffusion base material 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 the light can be greatly expanded in the layer 23B of the light propagation layer 23 on the diffusion base material 26 side. Furthermore, as shown in FIG. 11B, the point where the light incident on both ends of the unit lens of the light deflection element 28 is deflected and intersects is located in the layer 23A of the light propagation layer 23 on the light deflection element 28 side. It is desirable to do.

  Further, when the light propagation layer 23 has a multilayer structure of at least two layers, the farthest intersection α of the light deflection element 28 is the light exit surface of the light deflection element 28 (that is, the observer side F of the light propagation layer 23 and It may be contained in a layer in contact with the opposite surface 23a). 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, warpage of the optical device 24 and the optical uniform device 25 is prevented by matching the thermal linear expansion coefficient of the layer farthest from the viewer side with the thermal linear expansion coefficient of the diffusion base material 26 to approximately the same extent. Can do. Further, the warp of the optical device 24 and the optical uniform device 25 can be prevented also by adjusting the thickness of the light propagation layer 23.

  The diffusion base material 26 preferably has a total light transmittance of 30% to 80%. If the total light transmittance is less than 30%, the brightness of the emitted light to the observer side F is lowered, which is not preferable. Conversely, if 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 diffusion base material 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 diffusion base material 26 is formed by dispersing a light diffusion region in a transparent resin.
As the transparent resin, a thermoplastic resin, a thermosetting resin or the like can be used. For example, a polycarbonate resin, an acrylic resin, a fluorine acrylic resin, a silicone acrylic resin, an epoxy acrylate resin, a polystyrene resin, a cycloolefin polymer, Methyl styrene resin, fluorene resin, polyethylene terephthalate (PET), polypropylene, acrylonitrile styrene copolymer, acrylonitrile polystyrene copolymer, and the like can be used.

The light diffusion region is preferably made of light diffusion particles. This is because suitable diffusion performance can be easily obtained.
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 or 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.

When light diffusing particles are used as the light diffusing region, the thickness of the diffusing substrate 26 is preferably 0.1 to 5 mm.
When the thickness of the diffusion base material 26 is 0.1 to 5 mm, optimum diffusion performance and brightness can be obtained. On the other hand, if the thickness is less than 0.1 mm, the diffusion performance is insufficient, and if it exceeds 5 mm, the amount of resin is large and the luminance is reduced due to absorption.

In the case where a thermoplastic resin is used as the transparent resin, air bubbles may be used as the light diffusion region.
That is, the internal surface of the bubble formed inside the thermoplastic resin causes diffused reflection of light, and a light diffusing function equivalent to or higher than that when the light diffusing particles are dispersed can be exhibited. Therefore, the film thickness of the diffusion base material 26 can be made thinner.

Examples of such a diffusion base material 26 include white PET and white PP. White PET is a resin that is incompatible with PET, fillers such as titanium oxide (TiO ₂ ), barium sulfate (BaSO ₄ ), and calcium carbonate are dispersed in PET, and then the PET is stretched by a biaxial stretching method. By doing so, bubbles are generated around the filler to form.

  The diffusion base material 26 made of a thermoplastic resin may be stretched at least in the uniaxial direction. This is because bubbles can be generated around the filler by stretching in at least one axial direction.

  Examples of the thermoplastic resin include polyethylene terephthalate (PET), polyethylene-2, 6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, cyclohexanedimethanol copolymer polyester resin, isophthalic acid copolymer polyester resin, sporoglycol copolymer polyester. Resins, polyester resins such as fluorene copolymer polyester resins, polyolefin resins such as polyethylene, polypropylene, polymethylpentene, and alicyclic olefin copolymer resins, acrylic resins such as polymethyl methacrylate, polycarbonate, polystyrene, polyamide, polyether , Polyester amides, polyether esters, polyvinyl chloride, cycloolefin polymers, and copolymers containing these as components, Such as a mixture of these resins can be used are not particularly limited.

When bubbles are used as the light diffusion region, the thickness of the diffusion base material 26 is preferably 25 to 500 μm.
When the thickness of the diffusion base material 26 is less than 25 μm, it is not preferable because the sheet is insufficiently squeezed and wrinkles are easily generated in the manufacturing process and display. In addition, when the thickness of the diffusion base material 26 exceeds 500 μm, there is no particular problem in optical performance, but it is difficult to process into a roll shape due to increased rigidity, and it is difficult to make a slit easily. This is not preferable because the advantage of the thinness obtained is reduced.

The light uniform device 25 is preferably formed by integrally forming the diffusion base material 26, the light propagation layer 23, and the light deflection element 28 by a multilayer extrusion method. The light uniform device 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 light uniform device 25 may be formed by integrating the diffusion base material 26 and the light propagation layer 23 separately by an extrusion method, injection molding, or the like, and then integrating them with an adhesive material or an adhesive material.
For example, as the adhesive material or the adhesive material, the diffusion base material 26 and the light propagation layer 23 can be bonded using a generally used laminate or the like.

  The light uniform device 25 of the present invention can have a concavo-convex shape on the surface 26 b on the viewer side F of the diffusion base material 26. As shown in FIG. 12, the unevenness shape is given to the emission surface 26 b of the light uniform device 25, so that the surface 26 b on the viewer side F of the diffusion base material 26 is various compared to the case where the surface 26 b is substantially flat. Since the angled emission surface is formed, light can be emitted over a wider range, so that the diffusion performance is improved and the lamp image is reduced / disappeared. The light diffusion lens 21 is mentioned as an uneven | corrugated shape provided to an observer side.

As the light diffusion lens 21, a triangular prism shape as shown in FIG. This is because lens molding is easy and the direction of the emitted light can be easily controlled.
Further, a convex curved lens shape as shown in FIG. This is because the emission performance can be improved because the exit surface can be set at various angles.
The convex curved lens shape is more preferably an aspherical shape as shown in FIG. This is because the radius of curvature at the top can be reduced, and the diffusion performance is increased.
Further, the light diffusion lens 21 is preferably a curved triangular prism as shown in FIG. Since there is no surface parallel to the viewer-side surface 26b of the diffusing substrate 26 and the exit surface can be set at various angles, the diffusing performance is improved.
Further, the light diffusing lens 21 can combine a plurality of the above lens shapes. For example, as shown in FIG. 13 (e), a shape in which a triangular prism is combined on a convex curved lens may be used. This is because the diffusion performance is further increased by the diffusion effect of two or more lens shapes. In addition, the lens shape mentioned as the light deflection element 28 may be used.

The light diffusion lens 21 may be arranged by appropriately combining a plurality of the above-described lenses. For example, a diffusion lens 21 having a high diffusion performance may be disposed in a region directly above the light source 41, and a diffusion lens 21 having a low diffusion performance may be disposed between the light source 41 and the light source 41.
However, when the diffusing lens 21 is disposed on the surface of the diffusing substrate 26, for example, when the lens sheet 2 is disposed as the optical member 2, moire interference fringes may occur between the diffusing lens 21 and the lens sheet 2. Therefore, a method in which the periodic structure of the diffusing lens 21 and the periodic structure of the lens of the lens sheet 2 are adjusted to a pitch at which moire interference fringes do not occur, an angle is provided, or a diffusing film is further applied as the optical member 2. Is mentioned. When a member having no periodic structure such as a diffusing film or a deflection separation reflection sheet is disposed as the optical member 2, the above-described problem does not occur.

  In the light uniform device of the present invention, it is desirable that the exit surface, that is, the surface 26b on the viewer side F of the diffusion base material 26 is substantially flat. The reason will be described with reference to FIG.

FIG. 14 is a schematic cross-sectional view illustrating an example of the optical sheet, the backlight unit, and the display device of the present invention. In the optical sheet 52, the optical film 1 and the light uniform device 25 of the present invention are integrally laminated by the fixed layer 20.
The optical film 1 includes a light transmissive substrate 17 and a condenser lens 16, and a plurality of condenser lenses 16 are arranged at a constant pitch on a surface 17 b on the viewer side of the light transmissive substrate 17.

  By forming the condensing lens 16 on the observer-side surface 17b of the light-transmitting substrate 17, the light passing through the light uniform device 25 is condensed on the observer side F, and the luminance of the observer side F is obtained. Can be improved.

A surface 17 a opposite to the observer side F of the light transmitting substrate 17 is a substantially flat surface, a plurality of light masks 22 are formed, and a light uniform device 25 is bonded via the fixed layer 20. Yes.
As the material of the light transmissive substrate 17, a thermoplastic resin, a thermosetting resin, or the like can be used, and the material used for the light uniform device 25 may be used. By joining the materials used for the light uniform device 25, the occurrence of warpage can be suppressed.

  In addition, when unit lenses are formed on one surface and the other surface of one member, moire interference fringes may occur. However, the optical sheet 52 of the present invention is formed by the condensing lens 16 and the light deflection element 28. Since the diffusion base material 26 is inserted in between, moire interference fringes can be prevented. Here, since there is no diffusing element between the condenser lens 16 and the diffusing base material 26, and in order to bond the optical film 1 to the surface 26b on the viewer side F of the diffusing base material 26 without unevenness, It is desirable that the viewer-side surface 26b of the diffusion base material 26 is substantially flat.

  The shape of the condensing lens 16 is a convex curved surface shape, and has a third apex portion 16a having an arcuate surface and a third inclined surface 16b extending from the third apex portion 16a to the light transmitting substrate. Moreover, the condensing lens 16 is formed so that the distance between the 3rd inclined surfaces 16b which oppose may decrease gradually as it goes to the 3rd top part 16a. Furthermore, the condenser lenses 16 are spaced apart by the valleys 13 and are formed at a constant pitch.

Between the optical film 1 and the light uniform device 25, a plurality of light masks 22 and light transmission openings (air layers) 100 that separate the light masks 22 are provided. The pitch of the optical mask 22 and the air layer 15 is substantially the same as the pitch of the condenser lens 16.
The position of the optical mask 22 is formed at a position corresponding to the position of the valley portion 13. Therefore, the position of the air layer 100 is provided at a position corresponding to the third top portion 16 a of the condenser lens 16.

  Since the optical mask 22 is made of a material having a high light shielding property and is formed at a position corresponding to the position of the valley portion 13 that separates the condenser lens 16 formed on the surface 17b on the observer side F, Most of the light incident on the optical film 1 passes through the air layer 100 formed away from the optical mask 22 and is incident on the condenser lens 16, so that the light that has passed through the light uniform device 25 can be efficiently used. The light is emitted in the front direction (observer side) F.

  Here, the optical mask 22 can be comprised from light-reflective members, such as a metal material and a white reflective material, for example. In this case, the light reflected by the light mask 22 is returned to the diffusion base material 26 constituting the light uniform device 25, and after being diffused again by the diffusion base material 26, a part of the light again enters the optical film 1. Then, a part of the light is emitted from the light uniform device 25 to the light source side, reflected by the reflector constituting the lamp house, re-enters the light uniform device, is further diffused, and re-enters the optical film 1. By repeating this process, most of the light from the light source 41 can be emitted to the observer side F.

  When the optical mask 22 is made of a light reflective member, the reflectance is desirably 80% or more. If the reflectance is 80% or more, most of the light incident on the optical film 1 can be incident on the condenser lens 16 from the air layer 100, so that the luminance on the observer side F increases. If the reflectance is less than 80%, the amount of light transmitted through the optical mask 22 increases, and the amount of inefficient light incident on the condenser lens 16 increases, thereby causing a decrease in luminance on the viewer side F. .

  Examples of a method for producing the optical film 1 include a method using self-alignment. The condensing lens 16 is formed on the observer-side surface 17b of the light-transmitting substrate 17, and a photosensitive adhesive resin is bonded to the surface 17a opposite to the observer-side F of the light-transmitting substrate 17. By irradiating UV light from the condensing lens 16 side, the photosensitive adhesive resin at a position corresponding to the third top portion 16a of the condensing lens 16 is exposed to cure and lose adhesiveness. Thereafter, by transferring the optical mask 22, the optical mask 22 can be formed at a position corresponding to the valley portion 13 of the condenser lens 16.

  The optical sheet 52 is manufactured by laminating the optical film 1 manufactured as described above to the light uniform device 25 by the fixing layer 20 by lamination or the like. At this time, the material of the fixed layer 20 is appropriately selected so that the air layer 100 is maintained.

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 fixed layer 20 can be increased. When the elastic modulus of the fixed layer 20 is increased, when the optical film 1 and the light uniform device 25 are integrated, the fixed layer 20 does not enter the region of the air layer 100, so that the air layer 100 can be held. It becomes easy.
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.

However, when a stretched film typified by PET is used as the light-transmitting substrate 17 constituting the optical film 1, the optical sheet 52 is warped in a convex shape toward the light source 41 due to heat generated from the light source 41. There is.
At this time, the material of the layer 23A on the light deflection element 28 side of the light propagation layer 23 having a multilayer structure of two or more layers can be used as a warp prevention layer. That is, the layer 23A on the light deflection element 28 side of the light propagation layer 23 generates a moment that warps the optical sheet 52 into a concave shape on the light source side, thereby canceling each moment and preventing warpage. can do. For example, the light deflection element 28 is formed on the same material as the light transmissive substrate 17, and is bonded to the surface 23 a opposite to the observer side F of the light propagation layer 23 by the fixed layer 20 to prevent warping. be able to.

  The optical sheet 52 produced as described above is an optical film including the light uniform device 25 that uniformly diffuses the light H from the light source 41, the air layer that efficiently enters the condensing lens 16, and the light mask 22. 1, the single optical sheet 52 can satisfy the diffusion / condensing function.

FIG. 15 is a schematic cross-sectional view showing another example of the optical sheet, the backlight unit, and the display device of the present invention. In the optical sheet 52, the optical film 1 and the light uniform device 25 of the present invention are integrally laminated by the fixed layer 20.
The optical film 1 includes a light transmissive substrate 17 and a condenser lens 16, and a plurality of condenser lenses 16 are arranged at a constant pitch on a surface 17 b on the viewer side of the light transmissive substrate 17.

  By forming the condensing lens 16 on the observer-side surface 17b of the light-transmitting substrate 17, the light passing through the light uniform device 25 is condensed on the observer side F, and the luminance of the observer side F is obtained. Can be improved.

The surface 17a opposite to the observer of the light transmitting substrate 17 is a substantially flat surface, a plurality of ribs 29 are formed, and the light uniform device 25 is joined.
As the material of the light transmissive substrate 17, a thermoplastic resin, a thermosetting resin, or the like can be used, and the material used for the light uniform device 25 may be used. By joining the materials used for the light uniform device 25, the occurrence of warpage can be suppressed.

Examples of the shape of the condenser lens 16 include a triangular prism shape. Since the triangular prism has a high light condensing property in the front direction, an optical sheet 52 with high brightness can be obtained. The shape of the condensing lens 16 includes a convex curved surface shape. Since light is emitted not only in the front direction but also in various directions, the optical sheet 52 having a wide visual field range can be obtained.
The shape of the condenser lens 16 is not limited to the above-described shape, and can be appropriately selected depending on the light distribution characteristics required for the display to be used. For example, a microlens shape, a polygonal pyramid shape including a triangular pyramid and a quadrangular pyramid may be selected.

  A plurality of ribs 29 are provided between the optical film 1 and the light uniform device 25. The ribs 29 are arranged in the form of dots or lines, and ensure a sufficient air layer between the optical film 1 and the light uniform device 25. For example, by matching the valley portion 13 of the condenser lens 16 with the linear rib 29, it is possible to suppress a decrease in luminance and to prevent moiré interference fringes between the rib 29 and the condenser lens 16.

  As shown in FIG. 15A, the rib 29 may be formed on the surface 17a opposite to the viewer side of the light transmitting substrate 17 of the optical film 1, and as shown in FIG. 15B. In this manner, the light uniform device 25 may be formed on the viewer-side surface 26 b of the diffusion base material 26.

  As shown in FIGS. 14 and 15, the backlight unit 55 according to the embodiment of the present invention is a direct type backlight unit, and includes an optical sheet 52, a plurality of light sources 41, and a reflection plate 43. Yes.

  By disposing the optical sheet 52 on the observer side F of the plurality of light sources 41, the light H from the light sources 41 can be almost taken in. The light H is incident on the optical sheet 52 and is set as outgoing light K. The emitted light K is emitted with the brightness of the observer side F improved by the condensing effect of the optical sheet 52 while the lamp image of the light source 41 is eliminated by the diffusion effect of the optical sheet 52.

  FIG. 16 is a schematic plan view when the light source 41 and the light deflection element 28 are viewed from the X direction, as indicated by an arrow X in FIG. The light source 41 is a linear light source, and the light deflection element 28 is formed of a lenticular lens.

The angle θ ₄₁ formed by the axial direction j of the light deflection element 28 and the axial direction k of the light source 41 is preferably 20 degrees or less.
When the angle θ ₄₁ is 20 degrees or less, the lamp image of the light source 41 can be eliminated. On the contrary, when the angle θ ₄₁ exceeds 20 degrees, the effect of reducing the lamp image of the light source 41 becomes insufficient, and the lamp image of the light source 41 may be seen on the liquid crystal display screen. When the angle θ ₄₁ is 0 degree, the effect of the light deflecting element 28 is the greatest, so the angle θ ₄₁ is preferably 0 degree.

As shown in FIGS. 14 and 15, the display device 70 according to the embodiment of the present invention includes an image display element 35 and a backlight unit 50.
The image display element 35 includes two polarizing plates (polarizing films) 31 and 33 and a liquid crystal panel 32 sandwiched therebetween. The liquid crystal panel 32 is configured, for example, by filling a liquid crystal layer between two glass substrates.
The light K emitted from the backlight unit 50 is incident on the liquid crystal unit 32 via the polarizing filter 33 and is emitted to the viewer side F via the polarizing filter 31.

The image display element 35 is preferably an element that displays an image by transmitting / blocking light in pixel units. If the image is displayed by transmitting / blocking light in pixel units, the optical sheet 52 improves the luminance toward the observer side F, reduces the viewing angle dependency of the light intensity, and further, a lamp image. It is possible to display an image with high image quality by effectively using the light with reduced image quality.
The image display element 35 is preferably a liquid crystal display element. A liquid crystal display element is a typical element that transmits / shields light in pixel units and displays an image, and can improve image quality and reduce manufacturing cost compared to other display elements. Can do.

  In addition, you may arrange | position a diffusion film, a prism sheet, a polarization separation reflection sheet, etc. to the display apparatus 70 which is embodiment of this invention. By doing so, the image quality can be further improved.

  Since the display device 70 according to the embodiment of the present invention is configured to use the light K whose light collection / diffusion characteristics are improved by the optical sheet 52 described above, the luminance on the viewer side F is improved and the light intensity is increased. An image in which the distribution in the viewing angle direction is smoothed and the lamp image is reduced can be displayed on the image display element 35.

  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.

In this example, first, the influence of the difference in the thermal expansion coefficient of each layer constituting the optical device 24 on the warp of the optical device 24 itself was confirmed.
(Comparative Example 1)
As the light propagation layer 23, a 1 mm thick polycarbonate plate was prepared. As the light deflection element 28, a triangular prism was produced on a 100 μm-thick polypropylene sheet by the UV molding method, and laminated on a 1 mm-thick polycarbonate plate using an adhesive, whereby an optical device 24 was obtained.
The linear expansion coefficient of polycarbonate was 7 × 10 ⁻⁵ mm / mm / ° C., and the linear expansion coefficient of polypropylene was 11 × 10 ⁻⁵ mm / mm / ° C.
(Comparative Example 2)
As the light propagation layer 23, a 1 mm thick polycarbonate plate was prepared. As the light deflection element 28, a triangular prism was produced on a stretched polyethylene terephthalate film having a thickness of 100 μm by a UV molding method, and was laminated on a polycarbonate plate having a thickness of 1 mm using an adhesive material, whereby an optical device 24 was obtained.
Polycarbonate had a linear expansion coefficient of 7 × 10 ⁻⁵ mm / mm / ° C., and polyethylene terephthalate had a linear expansion coefficient of 8 × 10 ⁻⁵ mm / mm / ° C.
Example 1
As the light propagation layer 23, a 1 mm thick polycarbonate plate was prepared. As the light deflection element 28, a triangular prism was produced on a 100 μm-thick unstretched polyethylene terephthalate film by a UV molding method, and laminated on a 1 mm-thick polycarbonate plate using an adhesive material, whereby an optical device 24 was obtained.
Polycarbonate had a linear expansion coefficient of 7 × 10 ⁻⁵ mm / mm / ° C., and polyethylene terephthalate had a linear expansion coefficient of 8 × 10 ⁻⁵ mm / mm / ° C.

The optical device 24 produced in Comparative Examples 1 and 2 and Example 1 was left at a high temperature of 80 degrees for 24 hours, and the warping behavior of the optical device 24 was confirmed.
In Comparative Example 1, warpage occurred because the coefficient of linear expansion between the polycarbonate plate and polypropylene was 1.5 times or more.
In Comparative Example 2, the polycarbonate plate and the polyethylene terephthalate had substantially the same linear expansion coefficient, but because the polyethylene terephthalate was a stretched film, shrinkage occurred and warpage occurred.
In Example 1, since the polyethylene terephthalate was not stretched, a good optical device 24 without warping was obtained.

(Example 2)
A polypropylene film was laminated with an adhesive on the surface of the observer side of the optical device 24 having the configuration of Comparative Example 1 to obtain an optical device 25.
(Example 3)
A stretched white PET film was laminated as a diffusion base material 26 on the surface of the observer side of the optical device 24 having the configuration of Comparative Example 2 with an adhesive material, whereby a light uniform device 25 was obtained.

Similarly, the optical uniform device 25 produced in Examples 2-3 was allowed to stand at a high temperature of 80 ° C. for 24 hours to confirm the warpage behavior.
In Example 2, a good optical device 24 free from warpage was obtained.
In Example 3, a good light uniform device 25 without warping was obtained.

In this example, it was confirmed that an optical device free from warpage could be obtained by adjusting the linear expansion coefficients to be substantially the same. Moreover, when using a stretched film, it confirmed that a curvature could be prevented by using a stretched film on both surfaces of the optical device 24 and the optical uniform device 25. FIG.
Hereinafter, the optical characteristics of the display device 70 using the light uniform device 25 and the optical sheet 52 of the present invention will be described in detail.

A convex lenticular lens was prepared as the light deflection element 28. The pitch P of the convex lenticular lens is 100 μm, the angle θ formed by the tangent m at the junction 30 between the light propagation layer 23 and the convex lenticular lens and the surface 23a opposite to the observer side of the light propagation layer 23 is 65 degrees. The height of the convex lenticular lens was set to 45 μm.
The materials of the light deflection lens 28, the light propagation layer 23, and the diffusion base material 26 are all polycarbonate (refractive index = 1.59).
The diffusion base material 26 contained an appropriate amount of a resin filler so that the total light transmittance was 60%, the haze value was 99%, and the thickness was 1.5 mm.
The light propagation layer 23 was made of a transparent material without containing a resin filler, and the total light transmittance was 87%. In the following examples, samples in which the thickness of the light propagation layer 23 was changed were produced.
(Comparative Example 3)
In the light uniform device 25 set as described above, the thickness of the light propagation layer 23 was set to 150 μm, and the light uniform device 25 was produced by a multilayer extrusion method.
(Example 4)
In the light uniform device 25 set as described above, the thickness of the light propagation layer 23 was set to 600 μm, and the light uniform device 25 was produced by a multilayer extrusion method.
(Example 5)
In the light uniform device 25 set as described above, the thickness of the light propagation layer 23 was set to 1 mm, and the light uniform device 25 was produced by a multilayer extrusion method.

On the surface of the observer side F of the light uniform device 25 produced as described above, a diffusion film, a 90-degree triangular prism sheet, and a diffusion film were arranged in this order.
These are disposed in the backlight 56 having a CCFL interval of 18 mm, and the distance between the CCFL and the light uniform device 25 is 5 mm, and the liquid crystal panel 35 is disposed on the observer side F of the backlight 56, whereby the display device 70 is provided. Obtained.

Next, a convex lenticular lens sheet was prepared as the light deflection element 28. The pitch P of the convex lenticular lens is 100 μm, the angle θ formed by the tangent m at the junction 30 between the light propagation layer 23 and the convex lenticular lens and the surface 23a opposite to the observer side of the light propagation layer 23 is 65 degrees. A convex lenticular lens having a height of 45 μm was UV molded on a 75 μm PET substrate.
Further, the light propagation layer 23 and the diffusion base material 26 were polycarbonate (refractive index = 1.59).
The diffusion base material 26 contained an appropriate amount of a resin filler so that the total light transmittance was 60%, the haze value was 99%, and the thickness was 1.5 mm.
The light propagation layer 23 was made of a transparent material without containing a resin filler, had a thickness of 600 μm, and a total light transmittance of 87%.
(Example 6)
The condensing lenses 16 are arranged at a pitch of 150 μm on a 75 μm PET base material on the surface of the observer side F of the produced light uniform device 25 so that the area of the optical mask 22 is 50% of the pitch of the condensing lenses 16. The formed optical film 1 was integrally laminated with an adhesive material to obtain an optical sheet 52.
(Example 7)
On the surface of the observer side F of the light uniform device 25 produced as described above, a diffusion film, a 90-degree triangular prism sheet, and a diffusion film were stacked in this order.
(Example 8)
An optical film 1 in which a 90-degree triangular prism is molded on a 75-μm PET base material and dot-shaped ribs 29 having a size of 50 μm × 50 μm are formed on the surface facing the 90-degree triangular prism was produced using an adhesive. The optical sheet 52 was obtained by being integrally laminated on the surface on the viewer side F of the light uniform device 25.

  The samples 3 to 5 produced as described above are placed in the backlight 56 with a CCFL interval of 18 mm and the distance between the CCFL and the light uniform device 25 of 5 mm, and the liquid crystal panel 35 is placed on the observer side F of the backlight 56. By arranging, the display device 70 was obtained.

Next, the light deflecting element 28 is made of polycarbonate as a material, the pitch P is 100 μm, the tangent line 1 at the junction 30 with the light propagation layer 23, and the surface 23a opposite to the observer side of the light propagation layer 23. A curved triangular prism having an angle θ of 65 degrees and a height of 55 μm was extruded with a sheet thickness of 200 μm.
The light propagation layer 23 and the diffusion base material 26 were made of polystyrene (refractive index = 1.59).
The light propagation layer 23 was made of a transparent material without containing a resin filler, had a thickness of 0.6 μm, and a total light transmittance of 89%.
In the following examples, samples in which the total light transmittance and the haze value of the diffusion base material 26 were changed were prepared by adjusting the amount of the diffusion particles constituting the diffusion base material 26.
(Comparative Example 4)
In the light uniform device 25 set as described above, the diffusion base material 26 was manufactured with a total light transmittance of 25%, a haze value of 99%, and a thickness of 2 mm.
Example 9
In the light uniform device 25 set as described above, the diffusion base material 26 was manufactured with a total light transmittance of 70%, a haze value of 99%, and a thickness of 1 mm.
(Comparative Example 5)
In the light uniform device 25 set as described above, the diffusion base material 26 was manufactured with a total light transmittance of 70%, a haze value of 90%, and a thickness of 0.5 mm.

The condensing lenses 16 are arranged at a 150 μm pitch on a 75 μm PET substrate on the surface of the observer-side F of the produced light uniform device 25 so that the width of the light mask 22 is 50% of the pitch of the condensing lenses 16. The formed optical film 1 was integrally laminated with an adhesive material to obtain an optical sheet 52.
The obtained optical sheet 52 is disposed in the backlight 56 having a CCFL interval of 18 mm, and the distance between the CCFL and the light uniform device 25 is 5 mm, and the liquid crystal panel 35 is disposed on the observer side F of the backlight 56. Thus, the display device 70 was obtained.

(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 set to display all white, and the entire screen was measured with a luminance unevenness measuring device (ProMetric 1200: manufactured by Radiant Imaging), and analysis was performed using luminance distribution data in a vertical direction of a plurality of cold cathode tubes.
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.

In Comparative Example 3, there was no problem in both luminance and warpage, but the light propagation layer 23 was too thin, so that the light source image could not be completely erased, resulting in NG.
In Example 4, there was no problem in both luminance and warpage, and the light source image disappeared (OK determination).
In Example 5, there was no problem in luminance and warpage, and the light source image disappeared (OK determination).
In Example 6, the luminance was high and almost no warping occurred (OK determination).
In Example 7, although a slight warpage occurred on the light source 41 side, it was 5 mm or less, which is a level that is not problematic in actual use (OK determination).
In Example 8, sufficient luminance was obtained (OK determination) although there was a slight decrease in luminance compared to the other examples.
In Comparative Example 4, there was no problem of warping and the light source image disappeared. However, since the total light transmittance of the diffusing substrate 26 was too low, the luminance was significantly reduced.
In Example 9, the luminance was high and there was no problem with warping (OK determination).
In Comparative Example 5, a very high luminance was obtained, but the light source image could not be completely erased because the haze value of the diffusion base material 26 was too low.

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 optical uniform device 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 | deviation element. (B) It is a figure which shows an example of the lens shape of an optical deflection | deviation element. (C) It is a figure which shows an example of the lens shape of an optical deflection | deviation element. (D) It is a figure which shows an example of the lens shape of an optical deflection | deviation element. (E) It is a figure which shows an example of the lens shape of a light deflection | deviation element. (F) It is a figure which shows an example of the lens shape of an optical deflection | deviation element. (A) It is a figure explaining the effect of the light diffusion of a light diffusion / reflection layer. (B) It is a figure explaining the effect of the light diffusion of a light diffusion / reflection layer. (A) It is a figure which shows an example which formed the light-diffusion / reflection layer in the 1st top part of the light deflection | deviation element. (B) It is a figure which shows an example which formed the light-diffusion / reflection layer in the 1st top part of the light deflection | deviation element. (C) It is a figure which shows an example which formed the light-diffusion / reflection layer in the 1st top part of the light deflection | deviation element. (D) It is a figure explaining the amount of wraparound to a 1st inclined surface at the time of forming a light-diffusion / reflective layer in the 1st top part of a light deflection | deviation element. (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) It is a figure which shows an example which formed the light-diffusion / reflection layer in the 1st top part of the light deflection | deviation element. (D) It is a figure which shows an example which formed the light-diffusion / reflection layer in the recessed part of the light deflection | deviation element. (A) It is a figure explaining Numerical formula 1 in case a light deflection | deviation element is a concave lens. (B) It is a figure explaining Numerical formula 2 in case a light deflection | deviation element is a concave lens. (A) It is a figure explaining the case where the lens height and pitch of a light deflection | deviation element are not constant. (B) It is a figure explaining the case where the lens height of a light deflection | deviation element is not constant. (C) It is a figure explaining the case where the lens height and pitch of a light deflection | deviation element 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 device. (B) It is a figure which shows the form at the time of shape | molding a light 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 injection | emission surface of the optical uniform device. (B) It is a figure explaining the case where the emission surface of an optical uniform device 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. (A) It is a cross-sectional schematic diagram of the display apparatus which is embodiment of this invention. (B) 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 display apparatus which is embodiment of this invention. (B) It is a cross-sectional schematic diagram of the display apparatus which is embodiment of this invention. It is a top view of the backlight unit which is an embodiment of the present invention. It is a cross-sectional schematic diagram which shows an example of arrangement | positioning of BEF. It is a perspective view of BEF. It is a graph which shows the relationship between light intensity and the angle with respect to a visual field direction.

Explanation of symbols

A: Light intensity distribution of BEF, B: Light intensity distribution of optical film, H, K: Light, P: Light deflection element pitch, p1: Light deflection element first inclined surface pitch, m: Tangent, T: Light propagation layer , Θ: angle formed by one surface of the light propagation layer and the tangent m, θ1, θ2, θ3: angle formed by tangent lines at each point of the light deflection element and one surface of the light propagation layer, n: refraction of the light propagation layer N0: refractive index of the light deflection element, n1: refractive index of the first layer of the light propagation layer, n2: refractive index of the second layer of the light propagation layer, F, F ′: observer side, X: planar view Direction, Ve: vertical direction of the image display device, Ho: horizontal direction of the image display device, θ41: angle formed by the axial direction j of the lenticular lens with the axial direction k of the linear light source, Δ: amount of light diffusion / reflection layer wrapping, α ... farthest intersection point, 1 ... optical film, 2 ... optical member, 13 ... valley, 16 ... condensing lens, 16a ... third top, 16 3rd inclined surface, 17 ... Light transmitting base material, 17a ... Surface opposite to the observer, 17b ... Surface on the observer side (flat surface), 20 ... Fixed layer, 21 ... Light diffusion lens, 21a ... Second Top part, 21b ... second inclined surface, 22 ... light mask, 23 ... light propagation layer, 23a ... surface opposite to the observer, 23b ... observer side surface, 23A ... layer on the light deflection element side of the light propagation layer , 23B ... layer on the diffusion substrate side of the light propagation layer, 24 ... optical device, 25 ... light uniform device, 26 ... diffusion substrate, 26a ... surface opposite to the observer, 26b ... surface on the observer side, 28 DESCRIPTION OF SYMBOLS ... Light deflection element, 28a ... First top part, 28b ... First inclined surface, 28c ... Light diffusion / reflection layer, 29 ... Fixed element (rib), 30 ... Junction point, 31, 33 ... Polarizing plate, 32 ... Liquid crystal panel 35 ... Image display element 41 ... Light source 43 ... Reflector (reflective film) 45 ... Backlight part 52 DESCRIPTION OF SYMBOLS ... Optical sheet, 55, 56 ... Backlight unit, 70, 72 ... Display apparatus, 100 ... Air layer, 182 ... Diffusion film, 184 ... Light diffusion film, 185 ... BEF, 186 ... Transparent member, 187 ... Unit prism.

Claims (3)

A linear light source;
A light deflection lens whose lens shape is a lenticular type, and an angle formed by a major axis direction of the lenticular lens and a major axis direction of the linear light source when viewed in plan is 20 degrees or less;
A light propagation layer disposed on a light exit surface side of the light deflection lens, on which light deflected by the light deflection lens is incident;
A light diffusing substrate on the light exit surface side of the light propagation layer;
A light uniform device comprising:
The light deflection lens includes a first apex portion and a first inclined portion that extends from the first apex portion to a surface on the linear light source side of the light propagation layer, and the first apex portion is compared with the first inclined portion. Consisting of arcs or ridges with a small radius of curvature,
And the refractive index of the light propagation layer is n, the pitch of the light deflection lens is P, and the tangent to the first inclined surface at the junction where the first inclined surface is bonded to the light propagation layer is When the angle between the surface of the light propagation layer and the linear light source side is θ,
A light uniform device in which the thickness T of the light propagation layer satisfies the following formula 1 ;
A liquid crystal display device.

The light uniform device is:
A light diffusing region dispersed in a transparent resin, the light diffusing base material having a total light transmittance of 30% to 80% and a haze value of 95% or more;
The light propagation layer having a total light transmittance of 80% or more and a haze value of 95% or less;
The liquid crystal display device according to claim 1, comprising: The first inclined portion is a shape having a curved first curved inclined portion, and an angle formed between a tangent line at each point of the first curved inclined portion and a surface on the light source side of the light propagation layer, The liquid crystal display device according to claim 1, wherein the liquid crystal display device continuously changes from 20 degrees to 90 degrees .

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