JP2010250037A - Optical component, backlight unit and display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical component which can reduce a lamp image and has high light collection/diffusion properties, and to provide a backlight unit obtained by using the optical component, and a display apparatus. <P>SOLUTION: The optical component 30 has: an optical shape to collect or diffuse light on at least one surface of the base material; and a rugged structure 31A, on the other surface thereof, in which the ten-point average roughness Rz is ≤200 (μm) and the arithmetic average roughness Ra is >0.1 and <1,000 (μm). The optical shape comprises a plurality of convex parts 32 constituting lenses arrayed while leaving a space between the adjacent convex parts and satisfies 0.5<Y/X<1.0, 50≤X≤200 (μm), and 0.02≤T/X (wherein X is the width of a portion of the convex part 32 contacted with the one surface of the base material; Y is the height of the convex part; T is the shortest space between the adjacent convex parts 32). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical component mainly used for illumination light path control in an optical display device typified by a flat panel display, a backlight unit using the same, a display device, and a method for manufacturing the optical component.

2. Description of the Related Art Conventionally, for example, in a display device represented by a liquid crystal display device (LCD), a backlight unit is arranged on the back side of a liquid crystal display element in which ON / OFF of each pixel is controlled according to an image signal. Light from the light unit is used as display light.
In such a liquid crystal display device, although the power consumption of the liquid crystal display element is small, the power consumption in the backlight unit is large. Therefore, when used in battery-powered devices such as laptop computers and mobile phones, attempts have been made to reduce the power consumption of the device by increasing the light use efficiency of the light source.

  Conventionally, as a method of improving the light use efficiency of the light source, a method of collecting diffused light from the backlight unit with an optical sheet and improving the front luminance has been taken, and in particular, it is a registered trademark of 3M Corporation in the United States. Brightness enhancement films (BEFs) are widely used as optical sheets.

As shown in FIG. 4, BEF 1 is a film in which unit prisms 3 having a triangular cross section are arranged at a constant pitch in one direction on the upper surface of a transparent substrate 2.
The unit prism 3 has a size (pitch) larger than the wavelength of light. The BEF collects light from “off-axis” and redirects or “recycles” the light “on axis” toward the viewer. Thereby, when the light incident from the flat surface of the substrate is emitted from the prism surface, it has an effect of collecting the light in the front direction, and the brightness of the display in the front direction can be improved.

However, when BEF1 is used as the outermost optical sheet, there are the following problems.
That is, since the vertical light of BEF1 is refracted on the surface of the prism 3 and emitted in the normal direction, the vertical viewing angle is very narrow compared to the horizontal viewing angle. Further, the light component due to the refraction action is unnecessarily emitted in the lateral direction as sidelobe light without proceeding in the visual direction of the viewer, and the luminance distribution emitted from BEF1 is as shown in the luminance distribution diagram of FIG. On the other hand, the front luminance when the angle with respect to the visual direction of the viewer is 0 ° is most enhanced, but a small light intensity peak occurs in the vicinity of ± 90 ° from the front, so that the light cannot be collected efficiently. there were.
Furthermore, since the apex of the prism 1 is sharp, it has a drawback that it is in contact with the liquid crystal panel and is easily damaged.

  Therefore, in order to compensate for these disadvantages of BEF1, a plurality of optical sheets are often laminated between the liquid crystal display element constituting the liquid crystal display device and the backlight unit. As an example, as shown in FIG. 6, in addition to the diffusion plate 4, the diffusion sheet 5, the BEF 1, and the optical sheet of the diffusion sheet 5 are laminated in this order to achieve desired optical characteristics.

  As described above, the optical sheet represented by the BEF 1 and the diffusion sheet 5 requires not only the improvement of the light utilization efficiency but also various functions such as removal of unevenness of the light source, securing the viewing area of the display, and maintaining the rigidity of the display. Generally, it is configured by superposing a plurality of optical sheets.

  However, when a plurality of optical sheets are used, the work for assembling the display device becomes complicated, which is affected by dust that has entered between the optical sheets, and prevents miniaturization and thinning. Moreover, it is necessary to newly use a light diffusing film of another member, and there is a problem that the number of members increases and the cost increases.

By the way, with the further thinning of liquid crystal TVs in recent years, the distance between the light source and the image display unit in the housing is narrowed, and the brightness of the dark part and the bright part generated between the plurality of light sources arranged in parallel on the same plane. There is a problem that uneven distribution, that is, a lamp image becomes conspicuous and light and dark appear in the display screen.
That is, the optical sheet has been strongly required to eliminate the lamp image.

  On the other hand, in recent years, the use of microlens sheets as shown in FIG. The microlens sheets shown in Patent Documents 1 and 2 are sheets in which substantially hemispherical microlenses 8 are irregularly arranged on the substrate 9, and have an advantage that the front luminance can be increased. .

  Further, as a method of eliminating the lamp image, a method of mixing light scattering particles in the optical sheet or providing an uneven structure on the sheet surface is used.

JP 2006-301528 A JP 2006-317486 A

  However, when light scattering particles are mixed as described above or a concavo-convex structure is provided on the surface, the lamp image can be reduced, but the luminance is reduced. Further, in the conventional microlens sheet, the ratio of width to height is generally 0.5 or less, and the brightness increasing effect is inferior compared to a prism sheet represented by BEF1.

  The present invention has been made in view of such circumstances, an optical component that enables reduction of a lamp image and has high light collection and diffusion characteristics, a backlight unit using the same, a display device, An object of the present invention is to provide a method for manufacturing the optical component.

In order to solve the above problems, the present invention proposes the following means.
The optical component of the present invention includes a light-transmitting base material, an optical shape that is provided on one surface of the base material to collect or diffuse light, and is provided on the other surface of the base material. A point average roughness Rz is Rz ≦ 200 (μm) and an arithmetic average roughness Ra is 0.1 <Ra <1000 (μm), and the optical shapes are spaced apart from each other. A plurality are arranged, each having a convex portion constituting a lens, and when the width of the portion in contact with the one surface of the convex portion is X and the height is Y, 0.5 <Y /X<1.0 and 50 ≦ X ≦ 200 (μm), and the width X of the convex portion and the shortest interval T between the convex portions are 0.02 ≦ T / X. It is characterized by.
That is, the present invention is an optical component having an optical shape for condensing or diffusing light on at least one surface of a substrate, and the ten-point average roughness Rz on the other surface is Rz ≦ 200 ( μm), and has an uneven structure with an arithmetic average roughness Ra of 0.1 <Ra <1000 (μm), and a plurality of the optical shapes are arranged at intervals from each other, and each has a lens. Having a convex portion to be configured, where X is the width of the portion in contact with the one surface of the convex portion, and Y is the height, 0.5 <Y / X <1.0, and 50 ≦ X ≦ 200 (μm), and the width X of the convex portion and the shortest interval T between the convex portions are 0.02 ≦ T / X.

According to the optical component having such a feature, the light emission surface with various angles can be formed compared to the case where the surface is substantially flat, so that light can be emitted to a wider range.
That is, when 200 (μm) <Rz or 1000 (μm) ≦ Ra, the light diffusion range is too wide, and high luminance cannot be obtained. On the other hand, when Ra ≦ 0.1 (μm), it is difficult to emit light over a wide range, and it is difficult to reduce the lamp image.
In this respect, in the present invention, since Rz ≦ 200 (μm) and Ra are set in the range of 0.1 <Ra <1000 (μm), the diffusion performance can be improved and the lamp image can be reduced. .
Moreover, by setting Y, X, and T in the above ranges, it is possible to sufficiently exhibit the light condensing or diffusing characteristics and exhibit high luminance.
That is, in the case of Y / X ≦ 0.5, since the slope of the convex portion is small, the light condensing property is weak and high luminance cannot be obtained. On the other hand, in the case of 1.0 ≦ Y / X, since the slope of the convex portion is large, scratches or the like are likely to occur at the top, and the light condensing or diffusing characteristics cannot be sufficiently exhibited. In this respect, in the present invention, since it is set in the range of 0.5 <Y / X <1.0, the light condensing or diffusing characteristics can be sufficiently exhibited and high luminance can be exhibited.
Further, in the case of X <50 (μm), there is a possibility that a diffraction grating may be generated or the shape may be distorted when the convex portion is molded. On the other hand, in the case of 200 <X (μm), there is a possibility that a diffraction grating may be generated or bubbles may easily enter during molding of an optical component, which is not preferable.
In this respect, in the present invention, since it is set in the range of 50 ≦ X ≦ 200 (μm), the light condensing or diffusing characteristics can be sufficiently exhibited and high luminance can be exhibited.
Further, in the case of T / X <0.02, it is not preferable because adjacent convex portions may be overlapped with each other in the process of forming the convex portions.
In this respect, in the present invention, since it is set in the range of 0.02 ≦ T / X, the light condensing or diffusing characteristics can be sufficiently exhibited and high luminance can be exhibited.

  In the optical component according to the present invention, the convex portion is preferably a microlens having a substantially hemispherical shape or a substantially elliptical hemispherical shape.

  In the optical component according to the present invention, the convex portions may be regularly or irregularly arranged.

  The optical component according to the present invention preferably includes a transparent material and transparent particles dispersed in the transparent material and having a refractive index different from that of the transparent material.

The backlight unit according to the present invention includes any one of the above-described optical components and a light source.
According to the backlight unit having such a feature, since the optical component is provided, the light condensing or diffusing characteristics can be sufficiently exhibited to exhibit high luminance.

A display device according to the present invention includes the backlight unit and a display panel.
According to the display device having such a feature, since the optical component is included, the light condensing or diffusing characteristics can be sufficiently exhibited to exhibit high luminance, and an image with good display quality can be displayed. it can.

The method for producing an optical component of the present invention includes forming an etching resistant layer on the surface of a mold material, irradiating the etching resistant layer with a laser beam, and opening the opening in the etching resistant layer by ablation occurring in a laser beam irradiated portion. The surface is etched through the opening formed in the etching resistant layer to form a recess in the surface, and the etching resistant layer is removed to produce a mold having a mold surface having a recess. And the optical component which has a convex part is manufactured by transcribe | transferring the shape of the said recessed part of the said mold surface to an optical material, It is characterized by the above-mentioned.
That is, in the manufacturing method according to the present invention, an etching resistant layer is formed on a substrate, a laser beam is irradiated to the etching resistant layer, and an opening is formed in the etching resistant layer by ablation occurring in the laser beam irradiated portion. Forming and etching the substrate through an opening formed in the etching resistant layer to form a recess in the substrate, removing the etching resistant layer to produce a mold having a recess, An optical component manufacturing method comprising manufacturing an optical component having a convex portion by transferring a shape to an optical material.
By using such a manufacturing method, an optical component having a desired convex part can be molded.

  According to the optical component, the backlight unit, and the display device of the present invention, high front luminance can be obtained while providing the optical functions of condensing and diffusing.

It is typical sectional drawing which shows schematic structure of the display apparatus which concerns on embodiment. It is sectional drawing which shows the optical component which concerns on embodiment. It is a top view of the optical component which concerns on embodiment. It is typical sectional drawing which shows schematic structure of BEF. It is a luminance distribution figure of the light radiate | emitted from BEF. It is typical sectional drawing which shows schematic structure of the conventional display apparatus. It is a figure which shows schematic structure of the lens sheet of patent document 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view showing a schematic configuration of a display device according to the embodiment, FIG. 2 is a sectional view showing an optical component according to the embodiment, and FIG. 3 is a plan view of the optical component according to the embodiment.

As shown in FIG. 1, the display device 100 according to the embodiment is configured by providing a liquid crystal panel (image display element) 90 on the light emission side of a backlight unit 80 that emits light upward. The liquid crystal display device displays an image by emitting display light whose display is controlled by an image signal from a liquid crystal panel (display panel) 90 upward.
Hereinafter, based on such an arrangement, the upper direction in FIG. 1 may be simply referred to as the front direction or the viewer side, and the lower direction may be simply referred to as the back side.

The liquid crystal panel 90 is provided on the back side and the viewer side of a liquid crystal cell (display element or panel) 91 that controls the transmission state of light according to an image signal for each of a plurality of pixel regions formed in a rectangular grid, for example. It is configured by laminating polarizing sheets 92 and 93 that control the polarization direction of light. The liquid crystal cell 91 includes a pair of glass substrates and a liquid crystal layer sandwiched between them.
In the present embodiment, the liquid crystal panel 90 is a so-called transmissive display panel, but may be a transflective display panel. Alternatively, instead of the liquid crystal panel 90 including the liquid crystal cell 91, another display panel such as a display panel that displays a still image with a light-transmitting colored pattern may be used.

The backlight unit 80 is a light emitting device having a light emitting surface having substantially the same area as the display screen of the liquid crystal panel 90, and the light source unit 10, the light diffusion plate 20, and the optical component 30 are stacked in order from the back side. (By being arranged). Further, the light diffusing plate 20 and the optical component 30 constitute an optical sheet 70.
In the case where a sufficient light diffusion effect can be obtained by the optical component 30, or when diffused light is emitted from the light source unit 10, the display device 100 may be configured such that the light diffusion plate 20 is not provided. .

  In the present embodiment, the light source unit 10 includes a plurality of linear light sources that form a cylinder shape extending in the depth direction of the paper as the light source 11 and are arranged at a constant pitch so as to be parallel to each other. A direct type system is adopted in which the back side and the side of the light source are surrounded by the lamp house 12.

  As the light source 11 as the linear light source, a cathode tube (CCFL), a semiconductor laser, an EL, an LED arranged in a line shape, or the like can be used. In addition, the lamp house 12 has a box shape in which an observer side is opened, and is composed of a light reflecting film such as a white film or a white sheet, or a sheet. Note that. The lamp house 12 may be configured by attaching a film, a sheet, or the like on a support such as a metal plate.

  In addition to the light source 11 as a linear light source, the light source 11 may be a point light source capable of emitting light radially. In this case, the light sources 11 are arranged in a matrix in a two-dimensional direction along the light emission surface of the backlight unit 80, and the back side and the side of the light source 11 thus arranged are surrounded by the lamp house 12. It is configured as a direct type.

The light source 11 as a point light source preferably employs a light emitting diode (LED). When forming this light emitting diode, for example, a method of emitting white light by combining light emitting elements emitting light of a single color is generally used. In mobile devices such as mobile phones, there is a white LED that emits pseudo white light by mounting a yellow phosphor on a light emitting element that emits blue light.
In addition, the light source 11 as the point light source is not limited to the above-described one, but, for example, is a device in which at least one other phosphor is mounted on one single-color light-emitting element, such as that provided in a mobile device. Also good. Furthermore, for example, a normal fluorescent lamp, a halogen lamp, a semiconductor laser, or the like may be used. Furthermore, the point light source is not limited to the above-described one, and it may be a single monochromatic LED element covered with at least one kind of phosphor.

  The diffusion plate 20 is composed of a transparent resin and fine particles or gas dispersed in the transparent resin. In this diffusing plate 20, reflection and scattering occur at the interface between the transparent resin and the refractive index of the fine particles, gas, or the like because they are different. As a result, luminance unevenness of the light emitted from the light source is suppressed. Further, by selecting the material, it is possible to control the luminance distribution in accordance with the characteristics required for the display light.

Examples of the transparent resin used for the diffusion plate 20 include polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, MS (acrylic and styrene copolymer) resin, epoxy acrylate resin, and polystyrene. Resins, cycloolefin polymers, methylstyrene resins, fluorene resins, PET, polypropylene, and the like can be used.
As fine particles, particles made of an inorganic oxide or particles made of a resin can be used. For example, transparent particles made of an inorganic oxide include particles made of silica, alumina, titanium oxide, or the like. Further, transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, particles of melamine-formalin condensate, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Examples thereof include fluorine-containing polymer particles such as fluoroethylene monohexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene monotetrafluoroethylene copolymer), and silicone resin particles. These fine particles may be used as a mixture of two or more.

  The diffusion plate 20 may have a multilayer structure, and each layer may be composed of different resins and fine particles. At this time, in order to achieve the diffusion performance, it is preferable that the refractive index difference between the transparent resin and the fine particles or air is 0.01 or more, thereby obtaining sufficient light scattering performance. The particle diameter of the fine particles is preferably 0.1 μm to 100 μm in order to obtain diffusion performance while ensuring luminance.

The optical component 30 has a configuration shown in detail in FIG. 2, and a plurality of optical shapes for condensing or diffusing light are arranged on one surface of a base portion 31 that is a base material.
This optical shape is composed of convex portions 32 for reorienting outgoing light emitted from the diffusion plate 20 and condensing it on the display screen side. These protrusions 32 may be arranged separately on the base 31 or may be formed by integrally forming the protrusion 32 and the base 31.

The surface on the diffusion plate 20 side of the base material 31 has a ten-point average roughness Rz of Rz ≦ 200 (μm), and an uneven structure 31A having an arithmetic average roughness Ra of 0.1 <Ra <1000 (μm). It is preferable that it is given. In this case, since the light from the light source 11 is scattered on the surface, it is possible to obtain effects such as reducing the lamp image and making it difficult to confirm the pins. In addition, when the uneven structure 31A is provided on the surface of the base 31 on the diffusion plate side, a gap can be obtained between the surfaces overlapped with the member superimposed on the display screen. Optical influences such as Newton rings due to the close contact with the material 31 can be prevented.
Further, the concavo-convex structure 31A can prevent scratches caused by rubbing.
Note that the optical component 30 having such a concavo-convex structure 31A or convex portion 32 is formed on the concavo-convex structure 31A before the sheet is cooled and cured, for example, after the material is melted and then extruded into a sheet shape by an extruder. Molding is performed by clamping the sheet using a mold roll having a corresponding mold surface and a mold roll having a mold surface corresponding to the convex portion 32.

The convex portions 32 have a microlens shape, and are regularly arranged with a plurality of regular intervals or irregularly with unequal intervals. Examples of the shape of the convex portion 32 include a substantially hemispherical shape as shown in FIG. 3A and a substantially elliptical shape as shown in FIG. 3B. As shown, a substantially hemispherical shape and a substantially elliptical spherical shape may be mixed.
When the convex portion 32 includes a substantially elliptical hemispherical shape, a desired luminance distribution can be obtained by controlling the ratio of orienting the major axes of the ellipse in the same direction. For example, as shown in FIG. 3B, when the ratio of the substantially elliptical hemispherical long axis in the horizontal direction (the horizontal direction when the optical component 30 is erected) is large, the diffusion plate 20 The diffused light emitted from the light tends to have a narrower half-value angle on the vertical side than the half-value angle on the horizontal side. This is based on the difference between the elliptical inclination rates. Thereby, the display apparatus 100 with a wide horizontal viewing angle can be provided.
In addition, in order to obtain the brightness increasing effect, the ratio of the width X to the height Y, which is the shortest width among the widths along the one surface of the base portion 31 of the convex portion 32, is 0.5 <Y / X <1.0 The width X is set within a range of 50 ≦ X ≦ 200 (μm) so that diffracted light is hardly generated at the convex portion and is difficult to be visually recognized from the display screen side.
In addition, it is technically difficult to dispose the convex portion 32 on one side of the base portion 31 without any deviation of 1 μm, and there is a possibility that the adjacent convex portions 32 may overlap. The ratio of the shortest interval T is set in the range of 0.02 ≦ T / X.

Here, the light diffusing plate 20 may have a plate shape, a plate shape, or a sheet shape, and the thickness thereof is preferably set within a range of 0.5 to 5 mm.
When the thickness of the light diffusing plate 1 is less than 0.5 mm, there is a problem that bending occurs because it is thin and has no stiffness. On the other hand, when the thickness of the light diffusing plate 1 exceeds 5 mm, there is a problem that the transmittance of light from the light source 11 is lowered.

As a material for molding the optical component 30, a material having optical transparency with respect to the wavelength of light emitted from the light source unit 10 is used. For example, a plastic material that can be used for an optical member is used. it can.
Examples of this material include polyester resin, acrylic resin, polycarbonate resin, polystyrene resin, MS (acrylic and styrene copolymer) resin, polymethylpentene resin, thermoplastic resin such as cycloolefin polymer, or polyester acrylate. And transparent resins such as radiation curable resins composed of oligomers such as urethane acrylate and epoxy acrylate, or acrylates. Further, depending on the application, fine particles may be dispersed in the transparent resin.
As the fine particles, particles made of an inorganic oxide or particles made of a resin can be used. For example, transparent particles made of an inorganic oxide include particles made of silica, alumina, titanium oxide, or the like. The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and their cross-linked products, melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Examples thereof include fluorine-containing polymer particles such as fluoroethylene monohexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene monotetrafluoroethylene copolymer), and silicone resin particles. These fine particles may be used as a mixture of two or more.

The convex portion 32 of the optical component 30 is molded by pouring such a material into a mold and solidifying it.
The mold is made as follows. First, an etching resistant layer is formed on the surface of the mold material. Next, the etching resistant layer is irradiated with a laser beam, and an opening is formed in the etching resistant layer by ablation occurring at the laser beam irradiated portion. Next, the surface is etched through the opening formed in the etching resistant layer to form a recess in the surface. Finally, by removing the etching resistant layer, a mold having a mold surface having a recess is produced.
And the optical component 30 which has the convex part 32 is manufactured by transcribe | transferring the shape of the said recessed part of the metal mold | die surface to an optical material.
More specifically, as a method for producing a mold, first, a lacquer in which carbon black is dispersed in a resin is applied to a copper-plated mold by a spray method, and then irradiated with an infrared laser having a wavelength of 1060 nm. And sublimate the lacquer.
Then, a die is attached to the iron chloride chromic acid solution to corrode copper in an isotropic shape in the depth direction and the width direction, and a portion corresponding to the convex portion 32 is produced.
In addition to the method of manufacturing the optical component 30 with such a mold, as a method of forming the convex portion 32 and the base portion 31, a mold in which the above-described shape is formed with a thermoplastic resin or an ultraviolet curable resin is used. Then, it can be molded by extrusion molding, injection molding, UV molding, or the like. At this time, the convex portion 32 and the base portion 31 may be molded separately or may be molded as an integral product. Moreover, when shape | molding the convex part 32 and the base part 31, a diffusing agent, such as a filler, can be disperse | distributed inside and it can also shape | mold.

Next, the optical action of the display device 100 will be described focusing on the action of the optical component 30.
Of the light emitted from the light source unit 10 in all directions, the light emitted to the display screen side enters from the back side of the diffusion plate 20. On the other hand, the light emitted to the back side of the light source unit 10 is reflected by the lamp house 12 and then enters the diffusion plate 20 on the display screen side.
The light incident on the diffusion plate 20 is appropriately scattered by the internal particles as it passes through, and proceeds to the display screen side as diffused light.
When the light emitted from the diffusion plate 20 is incident on the optical component 30, it is refracted, reflected, and scattered by the concavo-convex structure 31A and the convex portion 32, is condensed on the display screen side, and a desired luminance distribution is given to the liquid crystal panel. 90. The light emitted from the optical component 30 is incident on the liquid crystal panel 90 as light traveling in a range of a certain divergence angle along the optical axis of the optical shape, and in each pixel region controlled by the drive unit based on the image signal. Depending on the polarization state, light from a predetermined pixel region is transmitted as display light, and image display is performed.

  In the present embodiment, the optical component 30 includes the concavo-convex structure 31A and the convex portion 32, and the ratio of the width X to the height Y of the convex portion 32 is within the range of 0.5 <Y / X <1.0. Therefore, as described above, it is possible to obtain a brightness enhancement effect that cannot be achieved with a conventional microlens sheet. Furthermore, since the convex part 32 is used as a lens, generation | occurrence | production of the side lobe and moire interference fringe which arise when using BEF can be avoided.

  And, according to the backlight unit 80 of the present embodiment, the optical component 30 that can obtain the high brightness increase effect as described above is adopted, so that light with improved light collection and diffusion characteristics is emitted. be able to.

  Further, in the display device 100 of the present embodiment, the image display element 90 is a liquid crystal display element and uses the light whose light collection / diffusion characteristics are improved by the backlight unit 80. It is possible to improve the luminance, smooth the distribution of the light intensity in the viewing angle direction, and obtain an image with a reduced lamp image.

The condensing diffusion sheet 20, the backlight unit 80, and the display device 100 according to the embodiment of the present invention have been described above. However, the present invention is not limited to this, and does not depart from the technical idea of the present invention. It can be changed as appropriate.
For example, a diffusing film, a prism sheet, a polarization separating / reflecting sheet, or the like may be disposed on the display device 100. Thereby, the image quality can be further improved.

  While producing an example of the optical component of this invention as Examples 1-5, the optical component of the comparison object of these Examples 1-5 was produced as Comparative Examples 1-5, and the contrast test of the physical property was done.

(Production method of optical parts)
After the base cylinder was plated on the molding cylinder, the surface was leveled to smooth the cylinder surface. After that, a molding cylinder is set in the laser plate making machine, and 5 μm of ink with carbon dispersed in the resin is applied to the entire surface with a spray coater, and honeycomb structure (hexagonal close-packed structure) is applied with a laser irradiation machine (wavelength 1060 nm). Irradiate with focus so that A portion of the ink irradiated with the laser beam was ablated (sublimated), and a circular pattern was formed on the entire surface.
Thereafter, the cylinder having a circular pattern formed on the entire surface is isotropically eroded while rotating into a corrosive solution, and a microlens shape that is a convex portion is formed on the entire surface of the cylinder. 5 and the predetermined shapes shown in Comparative Examples 1 to 5 (see Table 1) were produced.
Using this cylinder having a plurality of microlenses and a cylinder having a concavo-convex structure, a lens sheet constituting an optical sheet was produced using thermoplastic polycarbonate resin beads as a material. Specifically, after melting the thermoplastic polycarbonate resin beads, the sheet is extruded by an extruder, and the microlens 32 and the concavo-convex structure 31A on the back surface are formed by a mold roll before the sheet is cooled and cured. Molded.

(Characteristic evaluation of optical components)
For Examples 1 to 5 and Comparative Examples 1 to 5 shown in Table 1, two types of characteristic evaluations were performed, namely, luminance distribution and appearance.
Regarding the evaluation of the lamp image and the external appearance, the diffusion image (RM721 manufactured by Sumitomo Chemical Co., Ltd.) and the optical components were assembled in the order from the light source side to the display device, and the lamp image and the external appearance were evaluated after lighting for 1 hour. Judgment of whether the appearance is okay, or whether the lamp image is okay, the white and black screens are displayed, and if the light and darkness between the light sources is visually recognized, it is visually recognized as rejected (x). If not, it is judged as pass (○), and various lens shapes are visually recognized from the display screen side of the display device from either up, down, left, or right ± 80 °, or luminance unevenness is visually recognized with the convex shape as a bright spot. If it was done, it was determined to be rejected (x), and if it was not visually recognized, it was determined to be passed (o).
For brightness distribution measurement, the diffuser (RM721 manufactured by Sumitomo Chemical Co., Ltd.) from the light source side and the optical components are assembled in the automatic viewing angle photometer (GP-5 Murakami Color Research Laboratory Co., Ltd.) in order, and brightness measurement with respect to the angle is performed. went. As a result, if the luminance was insufficient, it was determined to be unacceptable (x), and if sufficient luminance was obtained, it was determined to be acceptable (◯).

(result)
As can be seen from Table 1, the ten-point average roughness Rz and the arithmetic average roughness Ra are Rz ≦ 200 (μm), 0.1 <Ra <1000 (μm), and the ratio of the width X to the height Y is 0.5 <Y / X <1.0, the ratio of width X to height Y is 0.5 <Y / X <1.0, and width X is 50 ≦ X ≦ 200 (μm) In Examples 1-5, the lamp image, the luminance distribution, and the appearance all passed.
However, in Comparative Example 1 where 200 (μm) <Rz, the luminance distribution was rejected. Moreover, in the comparative example 2 which is Ra <= 0.1 (micrometer), the lamp image and the external appearance failed. Further, in Comparative Example 3 in which the ratio of the width X to the height Y was Y / X ≦ 0.5, the luminance distribution was rejected. Further, in Comparative Example 4 in which the width X was 200 <X and in Comparative Example 5 in which the ratio of the width X to the interval T was T / X <0.03, the appearance was not acceptable.
From this, by constructing the backlight unit 80 using the optical component 30 described in the embodiment, it is possible to reduce the lamp image and emit a high light collection / diffusion characteristic. I understood it.

DESCRIPTION OF SYMBOLS 10 Light source part 11 Light source 12 Lamp house 20 Diffusion plate 30 Optical component 31 Base (base material)
32 Convex part 70 Optical sheet 80 Backlight unit 90 Liquid crystal panel 91 Liquid crystal cell 92 Polarizing sheet 93 Polarizing sheet 100 Display device

Claims (7)

A substrate having translucency,
An optical shape provided on one surface of the substrate to collect or diffuse light; and
A concavo-convex structure provided on the other surface of the base material and having a ten-point average roughness Rz of Rz ≦ 200 (μm) and an arithmetic average roughness Ra of 0.1 <Ra <1000 (μm). Prepared,
A plurality of the optical shapes are arranged at intervals from each other, each having a convex portion constituting a lens,
When the width of the portion of the convex portion in contact with the one surface is X and the height is Y, 0.5 <Y / X <1.0 and 50 ≦ X ≦ 200 (μm). And
The width X of the convex portion and the shortest interval T between the convex portions are 0.02 ≦ T / X.
An optical component characterized by that.   The optical component according to claim 1, wherein the convex portion is a substantially hemispherical or substantially elliptical hemispherical microlens.   The optical component according to claim 1, wherein the convex portions are regularly or irregularly arranged.   4. The optical component according to claim 1, wherein the base material includes a transparent material and transparent particles that are dispersed in the transparent material and have a refractive index different from that of the transparent material. 5.   A backlight unit comprising the optical component according to claim 1 and a light source.   A display device comprising the backlight unit according to claim 6 and a display panel. An etching resistant layer is formed on the surface of the mold material,
Irradiating the etching resistant layer with a laser beam, forming an opening in the etching resistant layer by ablation occurring in the laser beam irradiated portion,
Etching the surface through the opening formed in the etching resistant layer, forming a recess in the surface,
A mold having a mold surface having a recess by removing the etching resistant layer is produced,
Producing an optical component having a convex portion by transferring the shape of the concave portion of the mold surface to an optical material;
An optical component manufacturing method characterized by the above.

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