JPH09288215A - Surface light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light emitting device whose luminance is made uniform in a display area. SOLUTION: A linear light source is arranged on the side surface having the maximum thickness of a transparent light transmission plate 1 whose cross section is formed to a wedge shape, and a light diffusion transmissive part is installed on the rear side of the light transmission plate 1, a rear reflection plate 4 is arranged on the rear side, and a light absorbing layer 7 is formed in a belt-like state on at least a part near the linear light source among the peripheral part of the plate 4 surface facing to the plate 1, a diffusion sheet is arranged on the front surface of the plate 1, a light source reflection plate is arranged so as to cover the linear light source surface positioned on the side opposite to the plate 1, and the light absorbing layer 7 is formed so that the layer may be made larger in width near a gate trace 8 remaining on one, or plural side surfaces among four side surfaces of the plate 1 after injection molding.

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 emitting device used for thin and lightweight laptop personal computers, word processors, liquid crystal TV backlights and the like.

[0002]

2. Description of the Related Art Conventionally, a linear light source 2 is arranged on a side surface of a transparent light guide plate 1 having a wedge-shaped cross section and having a maximum thickness, and a light diffusion / transmission part 3 is provided on the back surface of the light guide plate 1, and on the back surface thereof. An edge light type surface emitting device in which a back reflector 4 is arranged, a diffusion sheet 5 is arranged on the surface of the light guide plate 1, and a light source reflector 6 is arranged so as to cover the surface of the linear light source 2 opposite to the light guide plate 1. But,
It is used as a backlight for liquid crystal display devices (see FIG. 14).

Further, recently, with the downsizing of word processors, personal computers, and the like, it has become necessary to meet the technical requirement that the outer dimensions of the light guide plate 1 approach the dimensions of the display area. As a result, since the display area and the line light source 2 are close to each other, on the line light source 2 side in the display area 8 of the surface emitting device,
The strong light emitted from the display showed abnormally high brightness, and uneven brightness sometimes occurred. Further, even on the side surface side where the linear light source 2 is not arranged, uneven brightness may occur when the side surface reflection plate having strong scattering reflection is provided. In order to improve the uneven brightness, the light absorption layer 7 is formed in a band shape at least in the vicinity of the linear light source 2 in the peripheral portion of the surface of the back reflector 4 facing the light guide plate 1 (see FIG. 15). The light absorption layer 7 and the light scattering layer 12 are formed in a band shape at least in the vicinity of the linear light source 2 in the peripheral portion of the surface of the diffusion sheet 5 facing the light guide plate 1. Further, in some cases, the light absorption layer 7 and the light scattering layer 12 are formed such that the area ratio thereof becomes gradually smaller as the distance from the side surface where the light absorption layer 7 and the light scattering layer 12 are provided.

[0004]

However, since the light guide plate 1 having a wedge-shaped cross section is manufactured by the injection molding method, the gate mark 8 is left on one or more of the four side surfaces (see FIG. 16).

The injection molding method is to heat and melt a molding material,
In a plasticized state, pressure is applied to the cavity of the mold 9 that has been closed in advance to fill the cavity, and the solidified and solidified molded article 10 is obtained.
This is a method of obtaining a molded product 10 that is faithful to the mold 9, has high accuracy, and is stable, with high productivity. In addition,
The gate 1 is a molding portion solidified at the injection port when the molten molding material is injected into the cavity in the injection molding die 9.
1 (see FIG. 17). After injection molding, the gate part 11 is automatically cut when the mold is opened, or the gate part 11 is molded.
Is taken out from the mold 9 and then cut. As a result, the gate mark 8 having a rough cut surface remains on the surface of the molded product that has a mirror surface faithful to the inner wall surface of the mold cavity.
When the light guide plate 1 is injection molded, the gate portion 11 is provided on the side surface. This is because when the gate mark 8 remains on the front surface or the back surface of the light guide plate 1, the appearance defect becomes conspicuous.
This is because other members cannot be horizontally stacked on the front surface or the back surface of the.

If the gate mark 8 having the rough cut surface remains on the side surface of the light guide plate 1 as described above, the following problems occur in the surface light emitting device. That is, since the light guided from the linear light source 2 into the light guide plate 1 and reaching the side surface is scattered and reflected by the gate mark 8, the scattered and reflected light is displayed in the vicinity of the gate mark 8 in the display area of the surface emitting device. A large amount of light may be emitted into the area and the brightness may be higher than the surroundings.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to provide a surface emitting device having a uniform brightness in a display area.

[0008]

In order to achieve the above object, the surface emitting device of the present invention has a linear light source disposed on a side surface of a transparent light guide plate having a wedge-shaped cross section and having a maximum thickness. A light diffusion / transmission part is provided on the back surface, a back surface reflection plate is arranged on the back surface, and a light absorption layer is formed in a band shape at least near the linear light source in the peripheral portion of the surface of the back surface reflection plate facing the light guide plate. In a surface emitting device in which a diffusion sheet is arranged on the surface of the light source and a light source reflector is arranged so as to cover the surface of the linear light source opposite to the light guide plate, one or more of the four side surfaces of the light guide plate are left after injection molding. In the vicinity of the gate trace, the width of the light absorption layer was increased.

Further, in the surface emitting device of the present invention, the linear light source is arranged on the side surface of the transparent light guide plate having a wedge-shaped cross section and having the maximum thickness, and the light diffusing and transmitting portion is provided on the back surface of the light guide plate, and on the back surface thereof. A back reflector is arranged, a diffusion sheet is arranged on the surface of the light guide plate, and a light absorption layer is formed in a band shape at least in the vicinity of the line light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. In a surface emitting device in which a light source reflection plate is arranged so as to cover the side opposite to the light guide plate, the width of the light absorption layer is displayed in the vicinity of the gate mark left after injection molding on one or more of the four side surfaces of the light guide plate. It was configured to grow without invading the area.

Further, in each of the above-mentioned configurations, the area where the width of the light absorption layer is large may be formed so that the area ratio thereof gradually decreases as the distance from the gate mark increases.

Further, in each of the above-mentioned constitutions, the entire light absorption layer may be formed so that the area ratio thereof gradually decreases as the distance from the side surface on which the light absorption layer is provided increases.

Further, in each of the above-mentioned constitutions, the portion formed so that the area ratio of the light absorption layer is gradually reduced may be formed in a dot shape or a stripe shape.

Further, in the surface emitting device of the present invention, the linear light source is disposed on the side surface of the transparent light guide plate having a wedge-shaped cross section and having the maximum thickness, and the light diffusion / transmission part is provided on the back surface of the light guide plate, and the back surface thereof is provided. The back reflector is arranged, the diffusion sheet is arranged on the surface of the light guide plate, and the light scattering layer is formed in a band shape at least in the vicinity of the line light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. In the surface emitting device in which the light source reflection plate is arranged so as to cover the side opposite to the light guide plate, the width of the light scattering layer is large near the gate mark left after injection molding on one or more of the four side surfaces of the light guide plate. Configured as

Further, in the above structure, the area where the width of the light scattering layer is large may be formed such that the area ratio thereof gradually decreases as the distance from the gate mark increases.

In the above structure, the entire light scattering layer may be formed such that the area ratio thereof gradually decreases as the distance from the side surface where the light scattering layer is provided increases.

Further, in each of the above-mentioned structures, the portion formed so that the area ratio of the light scattering layer is gradually reduced may be formed in a dot shape or a stripe shape.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The surface emitting device of the present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a perspective view showing a light absorbing layer provided on a back reflector of a surface emitting device according to the present invention, and FIGS. 2 to 9 are light absorbing layers in one embodiment of the surface emitting device according to the present invention. Schematic diagrams showing the pattern of the light scattering layer, FIGS. 10 and 11.
Is a perspective view showing the light absorption layer provided on the diffusion sheet of the surface emitting device according to the present invention, and FIGS. 12 and 13 are perspective views showing the light scattering layer provided on the diffusion sheet of the surface emitting device according to the present invention. FIG. 14 is a sectional view showing an embodiment of a surface emitting device using a light guide plate having a wedge-shaped cross section. In the figure, 1 is a light guide plate, 2 is a linear light source, 3 is a light diffusion / transmission part, 4 is a back reflector, 5 is a diffusion sheet, 6 is a light source reflector, 7 is a light absorption layer,
Reference numeral 8 is a gate mark, 12 is a light scattering layer, and 13 is a display region.

As the light guide plate 1, a rectangular resin plate having a wedge-shaped cross section with a thickness of about 1.5 to 5 mm is used. The wedge-shaped cross section refers to a shape in which the back surface of the light guide plate 1 is inclined so that the thickness becomes thinner as the distance from one side surface of the light guide plate 1 increases. The slope may be linear as shown in FIG. 14 or curved. Further, there may be a portion that is not inclined. As a material for the light guide plate 1, for example, a resin such as acrylic, polycarbonate, polystyrene, acrylic styrene, or polyvinyl chloride can be used. In addition, the gate mark 8 is left on one or more of the four side surfaces of the light guide plate 1 of the present invention. Gate mark 8
May be left on one side surface.

As the line light source 2, 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. By arranging the linear light source on the side surface having the maximum thickness of the light guide plate 1 having a wedge-shaped cross section, the traveling direction is gradually changed every time the light incident on the light guide plate 1 at the angle of total reflection is repeatedly totally reflected. Then, at a certain stage, the light is emitted from the surface side of the light guide plate 1 beyond the critical angle for total reflection. Therefore, as compared with the case where the linear light source 2 is arranged on one side surface of the light guide plate 1 having a uniform thickness, more light is emitted, and high brightness that can be applied to the color liquid crystal TV can be obtained.

The light diffusing and transmitting portion 3 is connected to the light guide plate 1 from the linear light source 2.
The light guided inside is scattered and reflected, and a part of the light is directed toward the front surface side of the light guide plate 1. The light is evenly distributed by changing the area ratio depending on the place where it is provided. In order to change the area ratio of the light diffusion transmission part 3, the light diffusion transmission part 3 is formed by dots having an arbitrary shape, and the dot size is changed or the number of dots is changed depending on the position. 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. As a method of forming the light diffusion / transmission part 3, a printing method such as gravure printing, offset printing, screen printing using a matte ink, a transfer method, a molding simultaneous transfer method, or a method in which the back surface of the light guide plate 1 is uneven is used. is there. 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 lower than that of the light guide plate 1 is used, the light diffusion property can be further improved.

The back reflector 4 reflects the light that could not be returned into the light guide plate 1 in the light diffusion / transmission part 3 to the light guide plate 1 side so that the light can be used efficiently. As the material of the back reflector 4, 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 that houses the light guide plate 1 and the linear light source 2 may be painted or printed in white to form the back reflector 4. The back reflector 4 is the light guide plate 1.
It may be partially fixed to the back surface by adhesion, or may simply be arranged.

The diffusion sheet 5 is for diffusing the light emitted from the surface of the light guide plate 1 to make the luminance distribution smooth. For example, the following materials are preferable as the material of the diffusion sheet 5. (1) A film or plate coated with a light diffusing substance. (2) A film or plate having a light diffusing property by itself. (3) A milky white resin film or plate. It is to be noted that the diffuser sheet 5 is arranged closer to the light guide plate 1 than the close contact with the light guide plate 1, and the diffuser sheet 5 is arranged at a distance from the light guide plate 1 so that total reflection is ensured inside the light guide plate 1 and the light guide plate 1 is secured. 1) There is little loss inside 1 and light can be reflected sufficiently. Moreover, the diffusion sheet 5 may be formed in a plurality of layers. Further, the diffusion sheet 5 may be partially fixed to the surface of the light guide plate 1 by adhesion, or may simply be arranged.

The light source reflection plate 6 reflects the light from the surface of the linear light source 2 opposite to the light guide plate 1 to the light guide plate 1 side so that the light can be used efficiently. As the material of the light source reflector 6, it is preferable to use the same material as the back reflector 4.
The distance between the linear light source 2 and the light source reflection plate 6 may be kept uniform by interposing a spacer therebetween.

The light absorption layer 7 absorbs at least the light irradiated to the vicinity of the linear light source 2 in the peripheral portion of the surface of the back reflector 4 facing the light guide plate 1 and emits light abnormally in the display area. To prevent Of course, the light-reflecting layer 6 may not be able to completely absorb light, and may absorb some light, for example. Examples of the method of forming the light absorption layer 7 include printing methods such as gravure printing, offset printing, and screen printing using an ink having a light absorbing function such as black and gray.

In the surface emitting device having the above structure, according to the present invention, as shown in FIG. 1, the width of the light absorption layer 7 is increased in the vicinity of the gate mark 8 so that the light in the vicinity of the gate mark 8 in the display area is reduced. To suppress the emission of light. It should be noted that, in the portion where the width of the light absorption layer 7 is large, the entire surface may be solidly formed (see FIG. 2), and when the scattering reflection by the gate mark 8 is weak, the reflection surface of the back reflector 4 is separated from the gap. It may be formed so as to be exposed (see FIG. 3). In addition, the light absorption layer 7
The area ratio of the portion having a large width may gradually decrease as the distance from the gate mark 8 increases (see FIGS. 4 to 6). Furthermore, the entire light absorption layer 7 is
The area ratio may be gradually reduced as the distance from the side surface provided with the light absorption layer 7 increases (see FIGS. 7 to 9). By gradually reducing the area ratio in this way, it is possible to prevent a significant difference in the amount of light emitted to the surface of the light guide plate 1 between the portion where the light absorption layer 7 is provided and the periphery thereof. To change the area ratio, for example, the light absorption layer 7
The area where the width is large or the entire light absorption layer 7 is composed of dots of any shape, and the size of the dots is changed (see FIGS. 5 and 8), or the number of dots is changed depending on the position. . 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, instead of dots, it may be formed in a stripe shape, for example, in the shape of comb teeth that become thinner toward the tip (see FIGS. 4 and 7) or the shape of annual rings that become thinner toward the outside (see FIGS. 6 and 9). Good.

Further, instead of forming the light absorption layer 7 on the back reflector 4 as described above, as shown in FIG. 10 or FIG. The absorption layer 7 may be formed in a band shape to absorb the light irradiated to the peripheral portion thereof and prevent the light from abnormally emitting in the display area. Of course, in this case as well, the width of the light absorption layer 7 is increased near the gate mark 8 to suppress the emission of light near the gate mark 8 in the display region. Since the formation of the light absorption layer 7 causes a shadow when it penetrates the display region 13, the light absorption layer 7 diffuses so as not to penetrate the display region 13 even if the width thereof is increased in the vicinity of the gate mark 8. The sheet 5 is formed.

Further, according to the present invention, instead of forming the light absorption layer 7 on the diffusion sheet 5, as shown in FIGS. 12 and 13, light scattering is performed at least in the vicinity of the linear light source 2 in the peripheral portion of one surface of the diffusion sheet 5. The layer 12 may be formed in a band shape, and a part of the light irradiated to the peripheral portion may be reflected to the light guide plate side by scattering so as to prevent abnormal light emission in the display area.
Of course, also in this case, the width of the light scattering layer 12 is increased near the gate mark 8 to suppress the emission of light near the gate mark 8 in the display region. It should be noted that the portion where the width of the light-scattering layer 12 is large may be solidly formed (see FIG. 2), or may face the light guide plate 1 of the diffusion sheet 5 when the scattering reflection by the gate mark 8 is weak. You may form so that a surface may be exposed from a clearance gap (refer FIG. 3). Further, the area ratio of the portion where the width of the light scattering layer 12 is large may be gradually reduced as the distance from the gate mark 8 is increased (see FIGS. 4 to 6). Furthermore, the entire light scattering layer 12 is
The area ratio may be gradually reduced as the distance from the side surface provided with the light scattering layer 12 is increased.
It is possible to prevent a significant difference in the amount of light emitted to the surface of the light guide plate 1 between the portion provided with and the surrounding area. 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 formed by dots having an arbitrary shape, and the dot size is changed (see FIGS. 5 and 8). See), and change the number of dots depending on the position. The shape of the dot is not particularly limited,
Any shape such as a round dot, a square dot, and a chain dot may be used. Further, instead of dots, it may be formed in a stripe shape, for example, in the shape of comb teeth that become thinner toward the tip (see FIGS. 4 and 7) or the shape of annual rings that become thinner toward the outside (see FIGS. 6 and 9). Good. Light scattering layer 1
Examples of the forming method of 2 include printing methods such as gravure printing, offset printing, and screen printing using an ink having a light scattering function such as white.

Further, the light absorption layer 7 or the light scattering layer 12 is formed on the diffusion sheet 5, and the light absorption layer 7 is formed on the back reflector 4.
May be used in combination.

Further, in the above structure, the diffusion sheet 5
A lens sheet may be arranged on the surface of (not shown).
The lens sheet is for raising the angle of the light emitted from the surface of the diffusion sheet 5 to increase the front brightness.
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 a large number of prisms (2) A translucent resin film in which a layer having a large number of prisms is formed on one surface (3) The light exit surface is higher than the light entrance surface A translucent resin film with a rough 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 constructions, a side reflector may be arranged on the side surface of the light guide plate 1 where the linear light source 2 is not arranged (not shown). The side reflector reflects the light that has been emitted from the side surface of the light guide plate 1 and has not returned to the side of the light guide plate 1 so that the light can be used efficiently. The side reflector may be arranged only on the surface facing the side surface of the light guide plate 1 on which the linear light source 2 is arranged, or may be arranged on all the side surfaces of the light guide plate 1 on which the linear light source 2 is not arranged. Good. 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. Further, when the side reflector is arranged as a reflective layer which is in direct contact with the side face of the light guide plate 1, there is the following method. That is, white coating or printing may be applied directly to the side surface of the light guide plate 1, or vapor deposition may be applied directly to the side surface of the light guide plate 1. The inner surface of the case that houses the light guide plate 1 and the linear light source 2 may be painted or printed in white to form a side reflector.

[0032]

【Example】

Example 1 240 mm in length, 170 mm in width, and the maximum thickness of the cross section is 3
A transparent acrylic resin plate having a wedge shape with a thickness of 1.5 mm and a minimum thickness of 1.5 mm, and having one gate mark on one side surface having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 240 mm and a diameter of 2.6 mm was arranged as a line light source on the side surface of the light guide plate having the maximum thickness. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. A light-absorbing layer is formed in a band shape with a width of 2 mm by screen-printing with a gray ink near the linear light source in the peripheral portion of the surface of the back reflector facing the light guide plate. The width of the layers was further increased by 2 mm. The area where the width of the light absorption layer was large was formed in a dot shape so that the area ratio thereof gradually decreased as the distance from the gate mark increased, and the rest was formed in a solid manner.
Further, on the surface of the light guide plate, a polycarbonate film having a textured surface of 130 μm in thickness (PCE manufactured by Keiwa Shoko Co., Ltd.)
S) was arranged as a diffusion sheet. Furthermore, a white polyethylene terephthalate film (E63 manufactured by Toray) having a thickness of 75 μm is arranged as a light source reflector so as to cover the surface opposite to the light guide plate on the surface of the linear light source, and both ends of the light source reflector are provided on both sides of the light guide plate. And a surface emitting device.

Example 2 250 mm in length, 190 mm in width, and the maximum thickness of the transverse section is 3
A transparent acrylic resin plate having a wedge shape with a thickness of 1.2 mm and a minimum thickness of 1.2 mm and having one gate mark left on one side having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 250 mm and a diameter of 2.4 mm was arranged as a line light source on the side surface having the maximum thickness of the light guide plate. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. A light-absorbing layer is formed in a band shape with a width of 5 mm by screen-printing with black ink in the vicinity of the linear light source in the peripheral portion of the surface of the back reflector that faces the light guide plate.
The width of the light absorption layer was further increased by 2 mm. Note that the light absorption layer was formed so that the area ratio thereof gradually decreased as it moved away from the side surface on which the light absorption layer was provided. On the surface of the light guide plate, a polycarbonate film (PCES manufactured by Keiwa Shoko Co., Ltd.) having a textured surface with a thickness of 130 μm was arranged as a diffusion sheet. further,
The thickness of the line light source is 75 μm so as to cover the side opposite to the light guide plate.
The white polyethylene terephthalate film (E63, manufactured by Toray Industries, Inc.) was placed as a light source reflector, and both ends of the light source reflector were overlapped with the front and back surfaces of the end portion of the light guide plate to form a surface emitting device.

Example 3 240 mm in length, 170 mm in width, maximum cross-sectional thickness of 3
A transparent acrylic resin plate having a wedge shape with a thickness of 1.5 mm and a minimum thickness of 1.5 mm, and having one gate mark on one side surface having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 240 mm and a diameter of 2.6 mm was arranged as a line light source on the side surface of the light guide plate having the maximum thickness. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. On the surface of the light guide plate, a polycarbonate film (PCES manufactured by Keiwa Shoko Co., Ltd.) having a textured surface with a thickness of 130 μm was arranged as a diffusion sheet. A light-absorbing layer is formed in a strip shape with a width of 5 mm by screen-printing with gray ink in the vicinity of the linear light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. Especially, in the vicinity of the gate mark, the light-absorbing layer is formed. The width of was increased by 3 mm without invading the display area. The area where the width of the light absorption layer was large was formed in a dot shape so that the area ratio thereof gradually decreased as the distance from the gate mark increased, and the rest was formed in a solid manner. Furthermore, a white polyethylene terephthalate film (E63 manufactured by Toray) having a thickness of 75 μm is arranged as a light source reflector so as to cover the surface of the linear light source opposite to the light guide plate. And a surface emitting device.

Example 4 Length 250 mm, Width 190 mm, Cross Section Maximum Thickness 3
A transparent acrylic resin plate having a wedge shape with a thickness of 1.2 mm and a minimum thickness of 1.2 mm and having one gate mark left on one side having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 250 mm and a diameter of 2.4 mm was arranged as a line light source on the side surface having the maximum thickness of the light guide plate. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. On the surface of the light guide plate, a polycarbonate film (PCES manufactured by Keiwa Shoko Co., Ltd.) having a textured surface with a thickness of 130 μm was arranged as a diffusion sheet. A light-absorbing layer is formed in a band shape with a width of 5 mm by screen-printing with black ink in the vicinity of the linear light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. Especially, in the vicinity of the gate mark, the light-absorbing layer is formed. The width of was increased by 3 mm without invading the display area. Note that the light absorption layer was formed so that the area ratio thereof gradually decreased as it moved away from the side surface on which the light absorption layer was provided. Furthermore, a white polyethylene terephthalate film (E63 manufactured by Toray) having a thickness of 75 μm is arranged as a light source reflector so as to cover the surface of the linear light source opposite to the light guide plate. And a surface emitting device.

Example 5 240 mm in length, 170 mm in width, maximum cross-sectional thickness of 3
A transparent acrylic resin plate having a wedge shape with a thickness of 1.5 mm and a minimum thickness of 1.5 mm, and having one gate mark on one side surface having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 240 mm and a diameter of 2.6 mm was arranged as a line light source on the side surface of the light guide plate having the maximum thickness. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. On the surface of the light guide plate, a polycarbonate film (PCES manufactured by Keiwa Shoko Co., Ltd.) having a textured surface with a thickness of 130 μm was arranged as a diffusion sheet. A light-scattering layer is formed in a strip shape with a width of 5 mm by screen-printing with white ink in the vicinity of the linear light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. Especially, in the vicinity of the gate mark, the light-scattering layer is formed. The width of was increased by 3 mm. The part where the width of the light scattering layer was large was formed in a dot shape so that the area ratio thereof gradually decreased as the distance from the gate mark increased, and the rest was formed in a solid manner. Furthermore, a white polyethylene terephthalate film (E63 manufactured by Toray) having a thickness of 75 μm is arranged as a light source reflector so as to cover the surface of the linear light source opposite to the light guide plate. And a surface emitting device.

Example 6 250 mm in length, 190 mm in width, maximum thickness of 3 in the transverse section
A transparent acrylic resin plate having a wedge shape with a thickness of 1.2 mm and a minimum thickness of 1.2 mm and having one gate mark left on one side having the maximum thickness was used as a light guide plate. A cold cathode ray tube having a tube length of 250 mm and a diameter of 2.4 mm was arranged as a line light source on the side surface having the maximum thickness of the light guide plate. On the back surface of the light guide plate, a large number of dots were screen-printed using a matte ink containing silica in acrylic resin to provide a light diffusion / transmission part.
The surface of the light guide plate on which the light diffusion / transmission part is provided has a thickness of 188 μm.
The white polyethylene terephthalate film (E60L manufactured by Toray Industries, Inc.) was placed as a back reflector. On the surface of the light guide plate, a polycarbonate film (PCES manufactured by Keiwa Shoko Co., Ltd.) having a textured surface with a thickness of 130 μm was arranged as a diffusion sheet. A light-scattering layer is formed in a strip shape with a width of 5 mm by screen-printing with white ink in the vicinity of the linear light source in the peripheral portion of the surface of the diffusion sheet facing the light guide plate. Especially, in the vicinity of the gate mark, the light-scattering layer is formed. The width of was increased by 3 mm. The light-scattering layer was formed such that the area ratio thereof gradually decreased as the distance from the side surface where the light-scattering layer was provided was increased. further,
75 μm thick to cover the opposite side of the surface of the line light source from the light guide plate
The white polyethylene terephthalate film (E63, manufactured by Toray Industries, Inc.) was placed as a light source reflector, and both ends of the light source reflector were overlapped with the front and back surfaces of the end portion of the light guide plate to form a surface emitting device.

The surface emitting devices obtained as in Examples 1 to 6 were free from the influence of the gate marks and had uniform brightness in the display area as compared with the conventional surface emitting device.

[0039]

Since the surface emitting device of the present invention has the above structure, it has the following effects.

That is, according to the conventional structure, even when the brightness in the vicinity of the gate mark in the display region of the surface emitting device is higher than that in the surroundings, the width of the light absorption layer or the light scattering layer in the vicinity of the gate mark is large. The emission of light near the gate mark in the display area is suppressed. Therefore, it is possible to obtain a surface emitting device having a uniform brightness in the display area.

[Brief description of drawings]

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

FIG. 2 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 3 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 4 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 5 is a schematic view showing a pattern of a light absorbing layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 6 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 7 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 8 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 9 is a schematic view showing a pattern of a light absorption layer or a light scattering layer in an example of the surface emitting device according to the present invention.

FIG. 10 is a perspective view showing a light absorption layer provided on the diffusion sheet of the surface emitting device according to the present invention.

FIG. 11 is a perspective view showing a light absorption layer provided on the diffusion sheet of the surface emitting device according to the present invention.

FIG. 12 is a perspective view showing a light scattering layer provided on a diffusion sheet of a surface emitting device according to the present invention.

FIG. 13 is a perspective view showing a light scattering layer provided on a diffusion sheet of a surface emitting device according to the present invention.

FIG. 14 is a sectional view showing an example of a surface emitting device using a light guide plate having a wedge-shaped cross section.

FIG. 15 is a perspective view showing a light absorption layer provided on a back reflector of a surface light emitting device.

FIG. 16 is a perspective view showing a gate mark left on a side surface of a light guide plate having a wedge-shaped cross section.

FIG. 17 is a cross-sectional view showing a method for manufacturing a light guide plate having a wedge-shaped cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Line light source 3 Light diffusion / transmission part 4 Back surface reflection plate 5 Diffusion sheet 6 Light source reflection plate 7 Light absorption layer 8 Gate mark 9 Mold 10 Molded product 11 Gate part 12 Light scattering layer 13 Display area

Claims (9)

[Claims] 1. A linear light source is arranged on a side surface of a transparent light guide plate having a wedge-shaped cross section and having a maximum thickness, a light diffusion / transmission part is provided on a back surface of the light guide plate, and a back surface reflector is arranged on the back surface thereof. A light absorption layer is formed in a band shape at least in the vicinity of the linear light source in the peripheral portion of the surface of the reflection plate facing the light guide plate, and a diffusion sheet is arranged on the surface of the light guide plate to cover the surface opposite to the light guide plate on the surface of the linear light source. In the surface emitting device in which the light source reflector is arranged as described above, the width of the light absorption layer is large in the vicinity of the gate mark left after injection molding on one or more of the four side surfaces of the light guide plate. Surface emitting device. 2. A line light source is arranged on a side surface of a transparent light guide plate having a wedge-shaped cross section and having a maximum thickness, a light diffusion / transmission part is provided on a back surface of the light guide plate, and a back reflector is arranged on the back surface of the light guide plate. A diffusion sheet is arranged on the surface of the light plate, a light absorption layer is formed in a band shape at least in the vicinity of the line light source in the peripheral portion of one side of the diffusion sheet, and a light source reflection plate is provided so as to cover the side opposite to the light guide plate on the surface of the line light source. In the arranged surface emitting device, the width of the light absorption layer is large in the vicinity of the gate mark left after injection molding on one or more of the four side surfaces of the light guide plate without increasing the width of the display area. Surface emitting device. 3. The surface emitting device according to claim 1, wherein a portion of the light absorption layer having a large width is formed such that the area ratio thereof gradually decreases as the distance from the gate mark increases. apparatus. 4. The surface emitting device according to claim 1, wherein the entire light absorption layer is formed such that the area ratio thereof gradually decreases as the distance from the side surface where the light absorption layer is provided increases. . 5. The surface emitting device according to claim 3 or 4, wherein the portion formed so that the area ratio of the light absorption layer is gradually reduced is formed in a dot shape or a stripe shape. 6. A transparent light guide plate having a wedge-shaped cross section is provided with a line light source on a side surface having a maximum thickness, a light diffusion / transmission part is provided on a back surface of the light guide plate, and a back reflector is provided on the back surface of the light guide plate. A diffusion sheet is arranged on the surface of the light plate, a light-scattering layer is formed in a band shape at least in the vicinity of the linear light source in the peripheral portion of one surface of the diffusion sheet, and a light source reflection plate is provided so as to cover the surface opposite to the light guide plate on the surface of the linear light source. In the arranged surface light emitting device, the width of the light scattering layer is large in the vicinity of the gate mark left after injection molding on one or more of the four side surfaces of the light guide plate. 7. The surface emitting device according to claim 6, wherein the area where the width of the light scattering layer is large is formed such that the area ratio thereof becomes gradually smaller as the distance from the gate mark increases. 8. The surface emitting device according to claim 6, wherein the entire light-scattering layer is formed such that the area ratio thereof gradually decreases as the distance from the side surface on which the light-scattering layer is provided increases. 9. The surface emitting device according to claim 7, wherein the portion formed so that the area ratio of the light scattering layer is gradually reduced is formed in a dot shape or a stripe shape.