JP2009283384A - Laminated light guide plate, laminated diffusion plate, edge-light type backlight device, direct-down backlight device, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cope with limitation of increasing a light guide plate or a diffusion plate, even though the same with high performance having fine patterns can be produced by injection molding. <P>SOLUTION: The laminated light guide plate and the laminated diffusion plate are provided by joining films having fine structures such as prisms, fine pyramid structures, and reflection patterns and a transparent substrate. Respective components can be formed by a continuous process with high productivity, and they can be easily increased in size. Further, warps caused by environmental changes can be lessened by joining the films made of a base material with the same material quality on both surfaces of the transparent substrate. A highly-reliable liquid crystal display device capable of having a high-quality image display on a large screen can be achieved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a backlight device thereof.

  Thin and light liquid crystal display devices capable of displaying images have rapidly spread due to price reduction and development of high image quality technology due to progress in manufacturing technology, and are widely used in monitors for personal computers and TV receivers.

  A transmissive liquid crystal display device is generally used as the liquid crystal display device. The transmissive liquid crystal display device includes a planar light source called a backlight device, and forms an image by spatially modulating illumination light from the light source using a liquid crystal panel.

  As the backlight device, a light source such as a fluorescent tube and an LED is arranged on the side surface of a flat light guide plate, light is extracted from one main surface of the light guide plate, and is used as a planar light source. There is a direct type in which a light source such as a fluorescent tube or LED is arranged directly below to form a planar light source.

  The light guide plate or diffuser plate is a simple flat plate with flat surfaces, and is used together with an optical sheet such as a prism sheet or a diffuser sheet to achieve predetermined optical performance such as viewing angle and front luminance. It was the target.

Furthermore, in recent years, a configuration has been proposed in which directivity is provided or uniformity is improved by providing a microstructure such as a prism array or a protrusion structure on one surface of a light guide plate (Patent Document 1). reference). In addition, a configuration has been proposed in which light source unevenness is reduced by providing a fine structure such as a prism array or a protrusion structure on one surface of a diffusion plate (see Patent Document 2). By providing a fine structure on one surface in this way, functions and performance that cannot be realized with a simple flat plate are expected. As a method for obtaining a light guide plate or a diffusion plate having these fine structures, injection molding is generally used.
JP 2007-022803 A JP 2006-155926 A

  According to the injection molding method, a fine structure can be formed precisely and integrally, and a light guide plate or diffusion plate having a relatively small size can be efficiently produced.

  However, a molding machine with a clamping force proportional to the area is required. Therefore, there is a problem that production becomes inefficient or difficult for a large size. Therefore, there has been a problem that it cannot be applied to a large-screen liquid crystal display device exceeding the 40-inch type that has recently been developed.

  In view of the above problems, an object of the present invention is to provide a light guide plate or a diffusion plate having a fine structure on the surface that can be produced with high productivity even in a large size.

  In order to solve the above-described problems, the light guide plate and the diffusion plate of the present invention include an optical functional film in which a light control structure for controlling emitted light is formed on one surface of a film-like substrate made of a transparent material, and a transparent The structure formed by joining the flat base material which consists of material with the transparent material in the surface in which the said light control structure of the said optical function film is not formed is taken.

  Moreover, you may take the structure formed by further joining the film which has the base material which consists of the same material as the base material of the said optical functional film to the surface where the said optical functional film of the said flat substrate is not joined.

  According to the light guide plate or the diffusion plate of the present invention, since a film-like optical functional film and a transparent substrate capable of efficiently producing a large size by a continuous process are used, it is large and excellent in productivity, and has a fine structure on the surface. A light guide plate and a diffusion plate can be obtained.

  Further, by bonding films made of the same base material on both surfaces of the transparent base material, warping is less likely to occur due to environmental changes in temperature and humidity. By using this light guide plate or diffusion plate for a liquid crystal backlight, it is possible to realize a liquid crystal display device having excellent display performance and high reliability.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view showing an embodiment of a laminated light guide plate of the present invention.

  A prism film 11, a transparent substrate 12, and a reflective pattern film 13 are respectively formed (FIG. 1A). The prism film 11 and the reflective pattern film 13 are formed with high productivity by a continuous roll-to-roll process by applying UV resin on a base film such as PET and irradiating ultraviolet rays while being pressed against a roll-shaped mold. I can do it.

  Further, the transparent substrate 12 having both flat surfaces is formed by extruding a transparent resin material such as PET, acrylic, polycarbonate, etc. by heating and melting it, spreading it with a die, and forming a flat plate through two opposing cylindrical rolls. It can be continuously and efficiently produced by a molding method.

  In the prism film 11 and the reflection pattern film 13 thus obtained, the transparent adhesive material is transferred to the surface on which each prism or reflection pattern is not formed, and each is laminated on a flat transparent substrate to form a laminated type. The light guide plate 1 is obtained (FIG. 1B).

  In this way, it is possible to easily obtain a large light guide plate having fine structures such as prisms and reflection patterns on both sides. Further, if the base material is a laminated body made of the same material, warpage can be reduced. Moreover, even if it is a laminated body made of different materials such as PET and acrylic or polycarbonate having different water absorption rates and linear expansion coefficients, the environment changes if both sides of the film substrate are the same across the transparent substrate 12. Both sides are balanced and no warping occurs.

(Embodiment 2)
FIG. 2 is a cross-sectional view illustrating a main configuration of a liquid crystal display device 100 in which the edge light type backlight device 20 configured using the multilayer light guide plate 1 described in Embodiment 1 is used as a lighting device.

  The configuration of the edge light type backlight device 20 will be described. A fluorescent tube 21 is arranged on the side surface portion of the laminated light guide plate 1 composed of the prism film 11, the transparent substrate 12, and the reflective pattern film 13 so that light from the fluorescent tube efficiently enters the side surface portion of the light guide plate 1. 22 is enclosed. A reflective sheet 23 is installed adjacent to the reflective pattern film 13 side surface of the laminated light guide plate 1, and a diffusion sheet 24 and a prism sheet 25 are installed on the prism film 11 side surface, respectively.

  The liquid crystal display device 100 is configured by disposing a liquid crystal panel 30 on an edge light type backlight device 20.

  When the fluorescent tube 21 is turned on with the above configuration, the emitted light is incident on the light guide plate 1 from the side surface portion, and propagates in the side surface direction facing the incident side surface while repeating total reflection between the opposing main surfaces. The reflection pattern film 13 is provided with a fine pattern that reflects the propagating light toward the liquid crystal panel, and the light that reaches the fine pattern is transmitted through the prism film 11 to illuminate the liquid crystal. At this time, the liquid crystal panel 30 can be illuminated with substantially uniform light from the entire surface of the light guide plate 1 by appropriately setting the size and density of the fine reflection pattern.

  The prism sheet 11 reflects a part of the light from the reflection pattern, and controls the light distribution so that the intensity of the transmitted light increases in the normal direction of the liquid crystal panel surface, thereby improving the front luminance. do.

  Furthermore, the diffusion sheet 24 and an optical sheet such as a prism sheet 25 in which the prisms of the prism film 11 are orthogonal to each other are added to illuminate the liquid crystal panel 30 by performing unevenness correction and directivity control. The liquid crystal panel forms an image by adjusting the transmittance for each pixel in accordance with the video control signal.

  With this configuration, a large-screen liquid crystal display device with high display quality can be realized by a large light guide plate in which fine structures are arranged on both sides. In addition, since the light guide plate is laminated on both sides with films made of the same material base material, a highly reliable liquid crystal display device is realized that is less likely to cause image failure due to warping due to changes in temperature and humidity associated with lighting. I can do it.

(Embodiment 3)
FIG. 3 is a perspective view showing an embodiment of the laminated diffusion plate of the present invention.

  A prism film 41, a transparent substrate 42, and a diffusion film 43 are respectively formed (FIG. 3A). The prism film 41 and the diffusion film 43 can be made with high productivity by a continuous roll-to-roll process by applying UV resin on a base film such as PET and irradiating it with ultraviolet rays while being pressed against a roll-shaped mold. I can do it.

  Further, the transparent substrate 42 having both flat surfaces is formed by extruding a transparent resin material such as PET, acrylic, polycarbonate, etc. by heating and melting it, spreading it with a die, and then forming a flat plate through two opposing cylindrical rolls. It can be created continuously and efficiently by the method.

  In the prism film 41 and the diffusion film 43 thus obtained, the transparent adhesive material is transferred to the surface on which each prism or diffusion pattern is not formed, and then laminated on a flat transparent substrate to laminate diffusion. A plate 4 is obtained (FIG. 3B).

  In this way, it is possible to easily obtain a large light guide plate having a fine structure of prisms and diffusion patterns on both sides. Further, if the base material is a laminated body made of the same material, warpage can be reduced. Moreover, even if it is a laminated body made of different materials such as PET and acrylic or polycarbonate having different water absorption rates and linear expansion coefficients, the environment changes if both sides of the film substrate are the same across the transparent substrate 42. However, both sides are balanced and do not warp.

(Embodiment 4)
FIG. 4 is a cross-sectional view showing a main configuration of a liquid crystal display device 200 in which the direct type backlight device 50 configured using the multilayer diffusion plate 4 shown in the third embodiment is used as an illumination device.

  The configuration of the direct type backlight device 50 will be described. A plurality of fluorescent tubes 51 are arranged on the diffusion film side below the laminated diffusion plate 4 including the prism film 41, the transparent substrate 42, and the diffusion film 43. Further, the light from the fluorescent tube is surrounded by the reflection sheet 52 so that the light efficiently enters the diffusion plate 4. A diffusion sheet 54 and a prism sheet 55 are respectively installed on the surface of the laminated diffusion plate 4 on the upper prism film 41 side.

  The liquid crystal display device 200 is configured by disposing a liquid crystal panel 60 on a direct type backlight device 50.

  When the plurality of fluorescent tubes 51 are turned on with the above configuration, the emitted light is incident on the diffusion plate 4 from the surface of the diffusion sheet 54. The unevenness is reduced by diffusing the incident light by the diffusion pattern formed on the diffusion sheet 54.

  The prism sheet 55 effectively reflects light traveling in the normal direction of the liquid crystal panel among the light from the fluorescent tube 51 to reduce lamp unevenness due to direct emission. In addition, for the transmitted light, the light distribution is controlled so as to increase the strength of the normal method of the liquid crystal panel surface, thereby improving the front luminance.

  Furthermore, the diffusion sheet 54 and an optical sheet such as a prism sheet 55 in which the prisms of the prism film 41 are orthogonal to each other are added to illuminate the liquid crystal panel 60 by performing further unevenness correction and directivity control.

  The liquid crystal panel 60 forms an image by adjusting the transmittance for each pixel in accordance with the video control signal. By configuring in this way, a large-screen liquid crystal display device with a high display quality can be realized by the large laminated diffuser plate 4 in which the fine structures are arranged on both sides. In addition, since the laminated diffusion plate 4 is laminated on both sides with a film made of the same material, the liquid crystal display device is highly reliable and is less likely to cause image failure due to warping due to changes in temperature and humidity associated with lighting. Can be realized.

  In addition, the prism film 11 and the prism film 41 used in said embodiment are examples of an optical functional film. The shape of the light control structure that controls the emitted light is not limited to the prism array, and for example, a shape such as a lenticular lens array or a pyramidal structure is also possible.

  The reflective pattern film 13 and the diffusion film 43 used in the above embodiment are examples of optical films.

  In the above embodiment, the fluorescent tube is used as the light source. However, the present invention is not limited to this. For example, a plurality of LED light sources can be arranged side by side. If an LED light source is used in the direct type backlight device, the irradiation area can be locally controlled.

  According to the present invention, it is possible to provide a high-performance light guide plate or diffuser plate having a fine structure on the surface and having a fine structure on the surface, which is high in productivity and high in productivity even in a large size. A highly reliable liquid crystal display device can be provided.

The perspective view which shows the structure of embodiment of the laminated light-guide plate of this invention. Sectional drawing which shows the main structures of embodiment of the edge light type backlight of this invention, and a liquid crystal display device The perspective view which shows the structure of embodiment of the laminated | stacked diffusion plate of this invention. Sectional drawing which shows the main structures of embodiment of the direct type | mold backlight and liquid crystal display device of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated type light guide plate 4 Laminated type diffuser plate 11, 41 Prism film 12, 42 Transparent substrate 13 Reflective pattern film 43 Diffusion film 20 Edge light type backlight apparatus 50 Direct type backlight apparatus 21, 51 Fluorescent tube 22 Reflector 23, 52 Reflective sheet 24, 54 Diffusion sheet 25, 55 Prism sheet 30, 60 Liquid crystal panel 100, 200 Liquid crystal display device

Claims (9)

A light guide plate for illuminating light incident from the side surface from one of the opposing main surfaces in a planar shape,
An optical functional film in which a light control structure for controlling emitted light is formed on one surface of a film-like substrate made of a transparent material, and a flat substrate made of a transparent material, the light control structure of the optical functional film Joined with a transparent material on the surface where the body is not formed,
Laminated light guide plate. The transparent material that constitutes the flat substrate and the transparent material that constitutes the substrate of the optical functional film are the same material.
The laminated light guide plate according to claim 1. An optical film having a base material made of the same material as the base material of the optical functional film is further bonded to the surface of the flat substrate that is not bonded to the optical functional film.
The laminated light guide plate according to claim 1. The laminated light guide plate according to any one of claims 1 to 3,
A light source installed on a side surface of the laminated light guide plate,
Edge light type backlight device. A diffusion plate that diffuses and emits light incident from the back,
An optical functional film in which a light control structure for controlling emitted light is formed on one surface of a film-like substrate made of a transparent material, and a flat substrate made of a transparent material, are used for the light control structure of the optical functional film. Joined by a transparent material on the surface that is not formed,
Laminated diffuser. The transparent material that constitutes the flat substrate and the transparent material that constitutes the substrate of the optical functional film are the same material.
The laminated diffuser plate according to claim 5. An optical film having a base material made of the same material as the base material of the optical functional film is further bonded to the surface of the flat substrate that is not bonded to the optical functional film.
The laminated diffuser plate according to claim 5. The laminated diffusion plate according to any one of claims 5 to 7,
A light source installed on the back surface of the laminated diffusion plate,
Direct type backlight device. The backlight device according to claim 4 or 8,
A liquid crystal panel that modulates light irradiated from the back by the backlight device,
Liquid crystal display device.

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