JPH10340613A - Edge light type surface emitting device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a surface light emitting device which can be provided with uniform luminance when a liquid crystal display device is configured by being arranged on the back of a COG type liquid crystal module. The present invention is used for a liquid crystal display device having a COG type liquid crystal module in which a driving LSI chip 6 is directly mounted on a glass substrate. A line light source 8 is disposed on a side surface of a transparent light guide plate. A light diffusion transmission portion is provided on the back surface, a back reflection plate is provided on the back surface, a diffusion sheet 11 is provided on the surface of the light guide plate, and at least the line light source 8 of the periphery of the surface of the diffusion sheet 11 facing the light guide plate is provided. Light scattering layer 12 in the vicinity
In the edge light type surface light emitting device in which is formed in a strip shape, the width of the light scattering layer 12 is widened in the vicinity of the place where the driving LSI chip 6 is arranged in accordance with the arrangement pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge light type surface light emitting device used for a liquid crystal display device having a COG type liquid crystal module in which a driving LSI chip is directly mounted on a glass substrate. The edge light type surface light emitting device according to (1) is used for a thin and lightweight laptop personal computer, a word processor, a backlight of a liquid crystal TV, and the like.

[0002]

2. Description of the Related Art A conventionally known edge light type surface light emitting device 2 has a line light source 8 disposed on a side surface of a transparent light guide plate 7 and a light diffusion transmitting portion provided on a back surface 9 of the light guide plate 7. In this configuration, a back reflector 10 is arranged on the back surface, and a diffusion sheet 11 is arranged on the surface of the light guide plate 7 (see FIG. 3).

In recent years, as the size and weight of a word processor, a personal computer, and the like have become smaller and the screen has become larger, it has become necessary to satisfy the technical requirements of making the outer dimensions of the light guide plate 7 closer to the dimensions of the display area. The following problems and solutions existed. Since the display area and the line light source 8 are close to each other, the line light source 8 in the display area of the surface light emitting device has an abnormally high luminance due to the strong light from the line light source 8, and luminance unevenness may occur. Was. Further, even on the side surface on which the line light source 8 is not arranged, uneven brightness sometimes occurs due to strong scattered reflection on the storage case or the side reflector of the surface light emitting device. In order to improve the luminance unevenness, a light scattering layer 12 is formed in a band shape at least in the vicinity of the linear light source 8 in a peripheral portion of a surface of the diffusion sheet 11 facing the light guide plate 7. In some cases, the light scattering layer 12 is formed such that its area ratio gradually decreases as the distance from the side surface on which the light scattering layer 12 is provided increases.

[0004]

However, no matter how uniform surface light emission without luminance unevenness is obtained on the surface light-emitting device 2, this surface light-emitting device 2 may be mounted in a COG (chip on glass) as shown in FIG. There is a problem that brightness unevenness may newly occur when the liquid crystal display device is configured by arranging it on the back surface of the liquid crystal module 1 of (method).

[0005] The COG type liquid crystal module 1 is one in which a driving LSI chip is directly mounted on a glass substrate having a liquid crystal part. For example, a substrate is provided in which two glass plates 3 are stacked in a sandwich shape and an end portion is held by a holder 4, and a liquid crystal unit 5 is disposed at the center of the plane of the substrate, and a glass is formed around the liquid crystal unit 5. A large number of driving LSI chips 6 constituting driving elements of the liquid crystal unit 5 are arranged between the plates, and each chip 6 and an electrode of the liquid crystal unit 5 are connected by a wiring pattern formed on at least one glass surface. There is something.
Since the liquid crystal cell gap caused by the thickness of the anisotropic conductive film used to connect the driving LSI chip 6 and the electrode of the wiring pattern partially increases near the driving LSI chip, and luminance unevenness occurs on the liquid crystal surface. is there.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a surface light emitting device capable of obtaining uniform brightness at the stage when a liquid crystal display device is arranged on the back of a COG type liquid crystal module. Is to provide.

[0007]

In order to achieve the above object, the present invention is directed to a liquid crystal display device having a COG type liquid crystal module in which a driving LSI chip is directly mounted on a glass substrate. , Arrange a line light source on the side of the transparent light guide plate, and provide a light diffusion transmission part on the back of the light guide plate,
An edge light in which a back reflection plate is disposed on the back surface, a diffusion sheet is disposed on the surface of the light guide plate, and a light scattering layer is formed in a strip shape at least in the vicinity of the linear light source in a peripheral portion of the diffusion sheet facing the light guide plate. In the surface light emitting device of the system, the width of the light scattering layer is configured to be wide in the vicinity of the position where the driving LSI chip is arranged in accordance with the arrangement pitch.

In the above structure, the light scattering layer may be formed so that the area ratio thereof gradually decreases as the distance from the side surface on which the light scattering layer is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an edge light type surface light emitting device according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a view showing an embodiment of a diffusion sheet provided on a back reflector of a surface light emitting device according to the present invention. FIG. 2 is a diagram showing light scattering provided on a diffusion sheet of the surface light emitting device according to the present invention. FIG. 4 is a partially enlarged view showing an example of a layer. In the figure, 6 is a driving LSI chip, 8 is a line light source, 11 is a diffusion sheet, 12
Indicates a light scattering layer.

As the light guide plate, a rectangular resin plate having a thickness of about 1 to 30 mm is used. As a material of the light guide plate 1, for example, a resin plate or a glass plate of acrylic, polycarbonate, polystyrene, acrylic styrene, polyvinyl chloride or the like can be used. Further, an inclined surface portion may be formed on the back surface side of the light guide plate such that the thickness decreases as the distance from the line light source 8 increases. This slope may be curved or may have a portion that is not sloped.

As the line light source 8, a cathode ray tube such as a hot cathode ray tube or a cold cathode ray tube having a diameter of 2 to 3 mm is used. The shape of the cathode ray tube may be straight, L-shaped over two adjacent sides, or U-shaped over three adjacent sides. Further, a plurality of cathode ray tubes may be arranged.

The light diffusion transmitting portion scatters and reflects the light guided into the light guide plate from the linear light source 8 and directs a part of the light toward the surface of the light guide plate. By changing it, the light is evenly distributed. In order to change the area ratio of the light diffusion transmission portion, the light diffusion transmission portion is formed of dots of an arbitrary shape, and the dot size is changed or the number of dots is changed depending on the position. The shape of the dots is not particularly limited, round dots,
Any shape such as a square dot or a chain dot may be used.
Further, it may be formed in stripes instead of dots. Examples of the method of forming the light diffusion transmission portion include a printing method such as gravure printing, offset printing, and screen printing using a matte ink, a transfer method, a molding simultaneous transfer method, and a method in which the back surface of the light guide plate is provided with irregularities. As the matte ink, if an ink containing a particulate transparent substance such as calcium carbonate or silica having a refractive index substantially equal to or less than that of the light guide plate 1 is used, the light diffusivity can be further improved.

The back reflector reflects the light that cannot be returned into the light guide plate at the light diffusion / transmission portion to the light guide plate side so that the light can be used efficiently. As the material of the back reflector, for example, the following materials are preferable.
(1) A film or plate in which a white pigment is mixed in a resin.
(2) White painted or printed aluminum plate.
(3) A mirror-finished metal plate or a metal foil such as aluminum, or a film or plate on which a metal such as aluminum or silver is deposited. Further, the inner surface of the case accommodating the light guide plate and the line light source 8 may be painted or printed in white to form a back reflection plate. Further, the back reflection plate may be partially fixed to the back surface of the light guide plate by adhesion, or may be simply arranged.

The diffusion sheet 11 diffuses light emitted from the surface of the light guide plate to smooth the luminance distribution. As a material of the diffusion sheet 11, for example, the following materials are preferable. (1) A film or plate coated with a light diffusing substance. (2) A film or plate having its own light diffusing property. (3) Milky white resin film or plate. It should be noted that the diffusion sheet 11 is provided with an interval between the light guide plate and the diffusion sheet 1 rather than in close contact with the light guide plate.
Arranging 1 ensures total reflection inside the light guide plate,
Light can be sufficiently reflected inside the light guide plate with little loss. Further, the diffusion sheet 11 may be formed in a plurality of layers. Further, the diffusion sheet 11 may be partially fixed to the surface of the light guide plate by adhesion, or may be merely arranged.

The light scattering layer 12 reflects, toward the light guide plate, at least light radiated to the vicinity of the linear light source 8 in the peripheral portion of the surface of the diffusion sheet 11 facing the light guide plate, and abnormally emits light into the display area. To prevent you from doing so. The light scattering layer 12 may be formed by a printing method such as gravure printing, offset printing, or screen printing using an ink having a light scattering function such as white light.

In the surface light-emitting device having the above-described structure, according to the present invention, as shown in FIG. 1, the width of the light scattering layer 12 is increased in the vicinity of the place where the driving LSI chip 6 is arranged in accordance with the arrangement pitch. Then, light emission in the vicinity of the driving LSI chip 6 in the display area is suppressed. Also,
The area ratio of the entire light scattering layer 12 may gradually decrease as the distance from the side surface on which the light scattering layer 12 is provided decreases (see FIG. 2). By gradually reducing the area ratio in this way, it is possible to prevent a significant difference in the amount of light output to the light guide plate surface between the portion where the light scattering layer 12 is provided and the periphery thereof. In order to change the area ratio, for example, a portion where the width of the light scattering layer 12 is large or the entire light scattering layer 12 is constituted by dots of an arbitrary shape, the size of the dots is changed, and the number of dots is changed depending on the position. This is done by changing The shape of the dot is not particularly limited, and may be an arbitrary shape such as a round dot, a square dot, and a chain dot. Further, it may be formed in stripes instead of dots.

In the above structure, the diffusion sheet 1
A lens sheet may be arranged on the surface of the first lens. The lens sheet raises the angle of light emitted from the surface of the diffusion sheet 11 to increase the front luminance. As the material of the lens sheet, for example, the following materials are preferable. (1) A translucent resin film in which one surface is processed into a shape having many prisms (2) A translucent resin film in which a layer having many prisms is formed on one surface (3)
A light-transmitting resin film whose light exit surface is rougher than the light entrance surface. Note that examples of the light-transmitting resin film include a polycarbonate resin film, an acrylic resin film, and a polyethylene terephthalate resin film.

In each of the above structures, a light source reflector may be disposed so as to cover the surface of the line light source 8 opposite to the light guide plate. The light source reflector reflects light from the surface of the line light source 8 on the side opposite to the light guide plate toward the light guide plate so that the light can be used efficiently. As the material of the light source reflector, the same material as the back reflector may be used. The line light source 8
The distance between the light source and the light source reflector may be kept uniform by interposing a spacer between them.

In each of the above structures, a side reflector may be provided on the side of the light guide plate where the line light source 8 is not provided. The side reflector reflects the light that has been emitted from the side surface of the light guide plate and cannot return, to the light guide plate side so that the light can be used efficiently. The side reflector may be disposed only on the surface facing the side of the light guide plate on which the linear light source 8 is disposed,
A side reflector may be disposed on the entire side surface of the light guide plate where the linear light source 8 is not disposed. As a material of the side reflector, for example, the following materials are preferable. (1) A film or plate in which a white pigment is mixed in a resin. (2) White painted or printed aluminum plate. (3) A mirror-finished metal plate or a metal foil such as aluminum, or a film or plate on which a metal such as aluminum or silver is deposited. Also,
When the above-mentioned side reflection plate is arranged as a reflection layer directly adhered to the side surface of the light guide plate, there are the following methods. That is, it is preferable to apply or print white color directly on the side surface of the light guide plate, or to perform evaporation directly on the side surface of the light guide plate. Further, the inner surface of the case accommodating the light guide plate and the line light source 8 may be painted or printed in white to form a side reflector.

[0021]

EXAMPLE A wedge-shaped transparent acrylic resin plate having a length of 190 mm, a width of 250 mm, and a vertical cross section of a maximum thickness of 3 mm and a minimum thickness of 1.5 mm was used as a light guide plate. On one side of the light guide plate, a cold cathode ray tube having a tube length of 260 mm and a diameter of 2.4 mm was arranged as a line light source. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in an acrylic resin to provide a light diffusion transmission portion. On the surface of the light guide plate on which the light diffusion transmission portion is provided, a thickness of 1
An 88 μm light reflection film (E60L, manufactured by Toray Industries, Inc.) was disposed as a back reflection plate. A 130 μm-thick light diffusion film (KPCE manufactured by Ewa Shoko Co., Ltd.) is provided on the surface of the light guide plate.
S) was arranged as a diffusion sheet. A light-scattering layer is formed in a 2 mm-wide band by screen printing using a white ink on the periphery of the surface of the diffusion sheet facing the light guide plate. The width of the layer is determined by the arrangement pitch (2
(4.6 mm) to make it even wider by 4 mm. Note that the light scattering layer was formed in a dot shape such that the area ratio gradually became smaller as the distance from the side surface on which the light scattering layer was provided. Further, a light-reflective silver film (GR38W manufactured by Kimoto Co.) having a thickness of 84 μm is arranged as a light source reflector so as to cover the opposite side of the surface of the linear light source from the light guide plate.
Both ends of the light source reflector were superimposed on the front and back surfaces of the end portion of the light guide plate to obtain a surface light emitting device.

The surface light-emitting device obtained in this manner has C
At the stage where the liquid crystal display device was constructed by being arranged on the back of the OG type liquid crystal module 1, uniform luminance was obtained.

[0023]

The edge light type surface light-emitting device of the present invention has the above-mentioned structure, and has the following effects.

That is, since the width of the light scattering layer is widened in accordance with the arrangement pitch in the vicinity of the position where the driving LSI chip is disposed, the light scattering layer is disposed on the back of the COG type liquid crystal module 1 and Uniform luminance can be obtained at the stage when the display device is constructed.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a light scattering layer provided on a back reflector of a surface light emitting device according to the present invention.

FIG. 2 is a partially enlarged view showing one embodiment of a light scattering layer provided on a diffusion sheet of the surface emitting device according to the present invention.

FIG. 3 is an exploded perspective view of a liquid crystal display device including a COG type liquid crystal module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 COG type liquid crystal module 2 Surface light-emitting device 3 Glass plate 4 Holder 5 Liquid crystal part 6 Drive LSI chip 7 Light guide plate 8 Line light source 9 Back surface 10 Back reflection plate 11 Diffusion sheet 12 Light scattering layer

Claims (2)

[Claims] 1. A liquid crystal display device provided with a COG type liquid crystal module in which a driving LSI chip is directly mounted on a glass substrate, wherein a line light source is arranged on a side surface of a transparent light guide plate, and A light diffusion transmission portion is provided on the back surface, a back reflection plate is disposed on the back surface, a diffusion sheet is disposed on the surface of the light guide plate, and light is provided at least in the vicinity of the line light source in a peripheral portion of the surface of the diffusion sheet facing the light guide plate. An edge light type surface light emitting device in which a scattering layer is formed in a strip shape, wherein the width of the light scattering layer is widened in the vicinity of a place where a driving LSI chip is arranged in accordance with the arrangement pitch. Surface emitting device. 2. The edge light type surface light emitting device according to claim 1, wherein the light scattering layer is formed so that the area ratio thereof gradually decreases as the distance from the side surface on which the light scattering layer is provided.