JP2565830B2 - Surface emitting device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface emitting device used for a liquid crystal display device or the like.

[0002]

2. Description of the Related Art Conventionally, edge-light type surface emitting devices have been used as backlights of liquid crystal display devices. The surface emitting device of this type includes a light guide plate 1 having a light diffusion / transmission part patterned on the back surface, a case 6 for housing the light guide plate 1, and a linear light source 3 arranged on a side surface of the light guide plate 1. There is something. Further, there is one in which the linear light source 3 is housed in the case 6 together with the light guide plate 1, or a back surface reflection sheet 9 is arranged between the light guide plate 1 and the case 6 (see FIG. 8). Further, there is a light guide plate 1 in which a surface diffusion sheet is arranged on the front side.

However, in these surface emitting devices, the light guide plate 1 is used.
Was adhered to the case 6 directly or via the back reflection sheet 9 only with the double-sided tape, the light guide plate 1 could not be completely fixed to the case 6, and vibration during use,
Due to impact or the like, the light guide plate 1 may be displaced in the case 6 and fall out of the case 6.

Therefore, in order to solve this, the light guide plate 1
While providing the perforation 4 on the case, the case 7 may be provided with a projection 7 that is fitted into the perforation 4 (see FIG. 6), or the notch 5 may be provided in the light guide plate 1 while the pillar 8 that is fitted into the notch 5 may be provided as a case. 6 (see FIG. 7), the light guide plate 1 is completely fixed to the case 6 by further fitting the perforations 4 and the projections 7 or the notches 5 and the posts 8 in addition to the adhesion with the double-sided tape. Was devised to do.

[0005]

However, in the conventional surface emitting device, in the vicinity of the perforations or notches (A in FIG. 5), the light from the linear light source is provided by the perforations and protrusions, or the notches and columns (see FIG. 5). (Indicated by a middle arrow) is shielded from light, so that the brightness is lower than that of a portion where the distance from the linear light source is equal to A and the distance from the perforation or notch is farther than A (B in FIG. 5), It was not possible to obtain uniform surface emission.

Therefore, it is an object of the present invention to provide a surface emitting device in which the above drawbacks are eliminated.

[0007]

The surface emitting device of the present invention comprises:
In order to achieve the above object, a light guide plate having a perforation and a light diffusion / transmission part patterned on the back surface, a case for accommodating a light guide plate having a protrusion fitted into the perforation of the light guide plate, and a light guide plate In an edge-light type surface emitting device including a linear light source disposed on the side surface of the light source, the area ratio of the light diffusion / transmission part in the vicinity of the perforation is configured to gradually increase toward the perforation.

Further, the surface emitting device of the present invention is for accommodating a light guide plate having a light guide plate having a notch and a light diffusion / transmission part patterned on the back surface, and a column fitted into the notch of the light guide plate. In the surface emitting device of the edge light system, which is composed of the case and the linear light source arranged on the side surface of the light guide plate, the area ratio of the light diffusion and transmission part in the vicinity of the notch is configured to be gradually increased as the notch is approached. .

[0009]

In the present invention, since the area ratio of the light diffusion / transmission part in the vicinity of the perforation or cutout is gradually increased as it approaches the perforation or cutout, light shielding by the perforation and projections, or the cutouts and columns. Because of this, the light from the linear light source, which has been reduced, can be surface-emitted to the same extent as before the reduction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings. 1 is a partially enlarged plan view showing an embodiment of a light guide plate used in the surface light emitting device of the present invention, and FIGS. 2 and 3 are portions showing other embodiments of the light guide plate used in the surface light emitting device of the present invention. FIG. 4 is an enlarged plan view, and FIG. 4 is a graph showing the luminance distribution of a surface emitting device using the light guide plate of FIG.

Reference numeral 1 is a light guide plate, 2 is a light diffusion / transmission part, 3 is a linear light source, 4 is perforations, and 5 is a notch.

The linear light source 3 is arranged on the side surface of the light guide plate 1,
The light guide plate 1 is irradiated with light. As the line light source 3, a cathode ray tube such as a hot cathode ray tube or a cold cathode ray tube may be used.
The linear light source 3 may be arranged outside the case, or may be housed in the case together with the light guide plate 1. The linear light source 3 may be arranged on only one side surface of the light guide plate 1, or may be arranged on two or more side surfaces.

The light guide plate 1 is made of a transparent rectangular plate material having a thickness of about 1 to 30 mm and has perforations 4 and notches 5. As a material for the light guide plate 1, it is preferable to use resin such as acrylic, polycarbonate, polyvinyl chloride, or glass. The perforations 4 and the cutouts 5 are formed in any shape and size, and the perforations 4 include, for example, a circle having a diameter of 4 mm. Further, the notch 5 has, for example, a rectangular shape with a size of 2 × 4 mm. Further, the light guide plate 1 may have a plurality of perforations 4 and cutouts 5.

On the back surface of the light guide plate 1, there is formed a light diffusing / transmitting portion 2 whose area ratio appropriately changes according to the change in the brightness of the light from the linear light source 3 (indicated by the arrow in the figure). In particular, the area ratio of the light diffusion / transmission part 2 in the vicinity of the perforations 4 or the notches 5 is formed so as to gradually increase as the holes 4 or the notches 5 are approached (see FIGS. 1 to 3). The change in the area ratio of the light diffusion / transmission part 2 except for the vicinity of the perforations 4 or the notches 5 is usually such that the area ratio increases as the distance from the linear light source 3 increases. The light diffusion / transmission part 2 may be formed by a printing method such as screen printing or a transfer method using a matte ink. The place where the perforations 4 are formed is not limited to the outside of the formation region of the light diffusion / transmission part 2 as shown in FIGS. 1 and 3, and may be inside the formation region of the light diffusion / transmission part 2.

The case is a thin molded product for accommodating the light guide plate 1 and the like, and has a projection fitted in the hole 4 of the light guide plate 1 and a support post fitted in the notch 5 of the light guide plate 1. . The light guide plate 1 is completely fixed to the case by fitting the perforations 4 and the projections, or the notches 5 and the columns, and adhering it to the case with an adhesive material such as double-sided tape.

Further, the back surface reflection sheet may be arranged between the case and the light guide plate 1. At this time, the back surface reflection sheet is bonded to the case and the light guide plate 1 with an adhesive material such as double-sided tape. The following materials are preferable as the material of the back surface reflection sheet. (1) White PET film. (2) White painted or white printed aluminum plate. (3) A metal plate having a mirror surface, a metal foil such as aluminum, or a film or plate subjected to metal deposition.

Further, the surface diffusion sheet may be arranged on the front side of the light guide plate 1. As the surface diffusion sheet, a film coated with a light diffusion material may be arranged on the light guide plate 1. Further, as the surface diffusion sheet, a film having diffusivity itself or a milky white resin plate can be used.

<Example> As the line light source 3, one cold cathode ray tube was arranged on one side of the short side of the light guide plate 1. Light guide plate 1
An acrylic plate having an outer dimension of 200 mm in length, 150 mm in width, and 2 mm in thickness and provided with a perforation 4 having a diameter of 4 mm near the center of the linear light source 3 was used. In addition, on the back surface of the light guide plate 1,
Basically, the area ratio is inversely proportional to the distance from the linear light source 3, and in the vicinity of the perforation 4 (A), the distance from the linear light source 3 is equal to the vicinity of the perforation 4 and the distance from the perforation 4 is greater than A. The light diffusion transmission part 2 having an area ratio of 15% larger than that of the separated part (B) was formed by screen printing using matte ink (see FIG. 1).

As a back reflection sheet, E60 manufactured by Toray Industries, Inc.
Using, the double-sided tape was provided around the front side of the back reflection sheet.

As the case, a thin molded product which can accommodate the light guide plate 1 and which has a projection fitted into the hole 4 of the light guide plate 1 is used. In addition, the light guide plate 1 of the case
A double-sided tape was provided on the surface opposite to.

After the back surface reflection sheet was attached to the back surface of the light guide plate 1, the light guide plate 1 was housed in the case together with the linear light source 3. A surface diffusion sheet (diffusion film 100PBU manufactured by Kimoto Co., Ltd.) was arranged on the front side of the light guide plate 1.

When the brightness distribution of the surface emitting device thus obtained was examined along the line passing through the perforations 4 in the longitudinal direction of the light guide plate 1, the brightness distribution as shown by the solid line in FIG. In the vicinity (A), the area distribution of the light diffusing and transmitting portion 2 was not corrected, and the brightness distribution was more uniform than the brightness distribution of the comparative example shown by the broken line.

[0023]

Since the surface emitting device of the present invention has the above-described structure and operation, the following effects can be obtained. That is, it is possible to obtain a uniform surface emission without lowering the brightness near the perforations or notches.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view showing an embodiment of a light guide plate used in a surface light emitting device of the present invention.

FIG. 2 is a partially enlarged plan view showing another embodiment of the light guide plate used in the surface emitting device of the present invention.

FIG. 3 is a partially enlarged plan view showing another embodiment of the light guide plate used in the surface emitting device of the present invention.

4 is a graph showing a luminance distribution of a surface emitting device using the light guide plate of FIG.

FIG. 5 is a partially enlarged plan view showing a light guide plate used in a conventional surface emitting device.

FIG. 6 is a perspective view showing a surface emitting device in which a light guide plate has perforations.

FIG. 7 is a perspective view showing a surface emitting device in which a light guide plate has a notch.

FIG. 8 is a perspective view showing a surface emitting device in which a light guide plate does not have perforations and notches.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Light diffusion / transmission part 3 Line light source 4 Perforation 5 Cutout 6 Case 7 Protrusion 8 Support 9 Backside reflection sheet

Claims (2)

(57) [Claims] 1. A light guide plate having a perforation and a light diffusion / transmission part patterned on the back surface, a case for accommodating the light guide plate having a projection fitted into the perforation of the light guide plate, and a side face of the light guide plate. In the edge-light type surface light emitting device including the linear light source, the surface light emitting device is characterized in that the area ratio of the light diffusion / transmission part in the vicinity of the hole gradually increases as the hole approaches the hole. 2. A light guide plate having a notch and a light diffusion / transmission part patterned on the back surface, a case for accommodating the light guide plate having a post fitted in the notch of the light guide plate, and a side surface of the light guide plate. 2. An edge-light type surface light-emitting device including a line light source arranged in a line light source, wherein the area ratio of the light diffusion / transmission part in the vicinity of the notch gradually increases as it approaches the notch.