JP3547962B2 - Surface emitting device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an edge light type surface light emitting device suitable for a transmission type display device.
[0002]
[Prior art]
A surface-emitting device used as a backlight of a transmissive display device, for example, a transmissive liquid crystal display device, has a narrower non-light-emitting area as the display device has become narrower and thinner. The frame and the thickness have been reduced. For example, an optical sheet such as a diffusion sheet or a prism sheet, which has been placed with a planar overlap with the case, is placed with a reduced planar overlap with the case, so that the optical sheet has a thickness equivalent to the thickness of the optical sheet. It is trying to make it.
[0003]
By the way, in the edge light type surface light emitting device, in order to efficiently supply the light from the linear light source disposed on the side surface of the light guide plate to the light guide plate, a reflection sheet is arranged so as to surround the linear light source. As a structure for fixing one end of the reflection sheet, as disclosed in Japanese Patent Application Laid-Open No. 8-64021 or the like, a structure A in which a double-sided adhesive is attached to the upper surface of the light guide plate, and an eaves portion of the case A structure B in which a double-sided adhesive or the like is adhered to the back surface of the device is known. FIGS. 2A and 2B show schematic structures in the case where these structures A and B are applied to a thinned surface emitting device as described above.
[0004]
In the case of FIG. 2A employing the structure A, the adhesive 110 for bonding the reflection sheet 105 and the light guide plate 102 diffuses and reflects the light of the light source 103 in a region in contact with the light guide plate 102, and the light is diffused. As a result, there is a problem that abnormal light emission (bright line) occurs. In order to cope with this, gradation dot printing 111 is performed on the lower surface of the light guide plate 102 or the reflection plate in contact with the lower surface to prevent the occurrence of abnormal light emission.
[0005]
On the other hand, in the case of FIG. 2B employing the structure B, there is a problem that abnormal light emission occurs near the gap region 109 between the optical sheet 108 and the eaves 144 of the case 104. In order to cope with this, black printing 112 or the like for shielding or absorbing the abnormal light emission is applied to the surface of the optical sheet 108.
[0006]
As described above, the conventional structure requires an extra countermeasure structure in order to suppress abnormal light emission (e.g., a bright line).
[0007]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above points, and has as its main object to provide a surface light emitting device capable of obtaining uniform surface light emission. It is another object of the present invention to provide a surface-emitting device that can suppress occurrence of abnormal light emission (bright line or the like) with a simple structure.
[0008]
[Means for Solving the Problems]
A surface light emitting device according to the present invention includes a light guide plate having a light incident surface on a side surface and a light exit surface on an upper surface, a linear light source disposed opposite to the light incident surface of the light guide plate, and a light guide for the linear light source. A reflection sheet disposed so as to encompass the light incident surface of the light plate, an optical sheet disposed on the light exit surface, and a case for positioning and arranging these, and a light exit surface of the light guide plate; And a case having a corresponding opening, wherein the light source side edge of the optical sheet is arranged inside the edge of the case opening, and one end of the reflection sheet located on the light emitting surface side is provided in the case. Wherein one end of the reflection sheet is disposed so as to cover a gap formed between an edge of the case opening and a light source side edge of the optical sheet. .
[0009]
In the surface light emitting device of the present invention, the length of one end of the reflection sheet projecting inside the case does not exceed the distance between the effective display area of the display device used in combination with the surface light emitting device and the edge of the case opening. It is characterized by being arranged.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in the cross-sectional view of FIG. 1, the surface light emitting device 1 has a linear light source 3 opposed to one side surface 21 which is a light incident surface of a flat light guide plate 2 made of a transparent resin. The linear light source 3 is formed of, for example, a cold cathode tube having a diameter of 2 to 3 mm, and both end portions thereof are supported at appropriate places of the case 4. The case 4 is composed of upper and lower cases 41 and 42 for positioning and positioning the light guide plate 2 and the linear light source 3 and members attached thereto. In the upper case 41, an opening 43 for light extraction corresponding to the upper surface 22 serving as a light emission surface of the light guide plate 2 is formed, and an eave 44 having a predetermined width is formed so as to surround the opening 43. ing.
[0011]
In order to efficiently guide the light of the linear light source 3 to the light guide plate 2, the reflection sheet 5 is arranged so as to surround the linear light source 3. The reflection sheet 5 is made of a flexible white resin sheet or a resin film on which aluminum is deposited, and has one end 51 of the light guide plate 2 so as to cover the linear light source 3 and the light incident surface 21 of the light guide plate 2. The other end 52 is arranged between the upper surface 22 and the eaves 44, and the other end 52 is arranged between the lower surface of the light guide plate 2 and the lower case 42. One end 51 of the reflection sheet 5 is disposed with its edge 53 slightly protruding from the edge of the eaves 44 (= the edge of the opening 43) to the opening 43 side, and the back surface of the eaves 44 is coated with a double-sided adhesive 6 or the like. It is fixed. The other end 52 of the reflection sheet 5 is removably inserted between the lower surface of the light guide plate 3 and the lower case 42 to facilitate replacement of the linear light source 3. A predetermined number of heat-resistant resin O-rings 7 are mounted on the linear light source 3, and a predetermined space is secured between the linear light source 3 and the reflection sheet 5 by the O-ring 7.
[0012]
A predetermined number of optical sheets 8 such as a diffusion sheet and a prism sheet are arranged on the upper surface 22 of the light guide plate 3 in order to make the emitted light uniform. In this example, a diffusion sheet, two prism sheets, and a diffusion sheet are stacked in this order from the bottom. These optical sheets 8 are basically arranged on the eaves 44, but a part of the optical sheets 8, in this example, the three sheets from the bottom, is placed on the side of the linear light source 3 in order to make the device thinner. Are arranged in the opening 43 avoiding the eaves 44. As described above, since the edge on the side of the linear light source of some of the optical sheets 8 is located in the opening 43, the light of the light guide plate 2 is located between the edge of the optical sheet 8 and the edge of the eave 44. The gap 9 exposing the emission surface 22 is generated. Then, abnormal light emission often occurs due to light leakage from the vicinity of the gap 9, abnormal reflection by the edge of the optical sheet 8, and the like.
[0013]
However, since the one end edge 53 of the reflection sheet 5 is slightly protruded toward the opening 43 from the end edge of the eaves 44 so that the gap 9 is covered from below by the reflection sheet 5, the light exits from the light guide plate 2. Then, the light entering the gap 9 can be reflected or blocked by the reflection sheet 5, and the abnormal light emission caused by the light entering the gap 9 can be effectively reduced.
[0014]
Further, one end 53 of the reflection sheet 5 is positioned on the light source side of the optical sheet 8 located in the opening 43 so that the gap 9 and the vicinity of the light source side edge of the optical sheet 8 are covered from below by the reflection sheet 5. Since it is located slightly inside the edge, in addition to the light emitted from the light guide plate 2 and entering the gap 9, the light emitted from the light guide plate 2 toward the light source side edge of the optical sheet 8 is The light can be reflected or blocked by the reflection sheet 5, and the light entering the gap 9 and the abnormal light emission due to the edge reflection of the optical sheet 8 can be effectively reduced.
[0015]
If the length C by which the one end 51 of the reflection sheet 5 protrudes inward is made too long, the effective illumination area becomes narrower. It is determined corresponding to the area. For example, when the effective display area of the display device is set at a distance D from the eaves 44, the distance C from the eaves 44 is set so as not to exceed the distance D. Incidentally, when the surface light emitting device 1 is used in combination with a backlight of a 13.3 type liquid crystal display device, the distance D is set to about 1 mm. Is set to about 0.5 mm.
[0016]
As described above, since the abnormal light emission near the linear light source 3 can be suppressed by using the existing reflection sheet 5, the structure can be simplified. In addition, since the reflection sheet 5 is fixed not to the light guide plate 2 but to the case 4 side, there is almost no occurrence of abnormal light emission due to the adhesive portion between the reflection sheet 5 and the light guide plate 2.
[0017]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a surface light emitting device capable of suppressing abnormal light emission occurring near a linear light source and obtaining uniform surface light emission. Further, it is possible to suppress the occurrence of abnormal light emission by using an existing reflection sheet, and to provide a surface emitting device with a simplified structure.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of the present invention.
FIGS. 2A and 2B are cross-sectional views showing two types of conventional structures (structure A and structure B).
[Explanation of symbols]
Reference Signs List 1 surface emitting device 2 light guide plate 3 linear light source 4 case 5 reflection sheet 6 adhesive 8 optical sheet

Claims (2)

A light guide plate having light incident light on a side surface and light emission light on an upper surface, a linear light source disposed opposite to the light incident surface of the light guide plate, and the light incident surface of the linear light source and the light guide plate. And a case for positioning and arranging these, and a case having an opening corresponding to the light exit surface of the light guide plate. A light emitting device in which a light source side edge of the optical sheet is arranged inside an edge of the case opening, and one end of the reflection sheet located on the light emitting surface side is fixed to the case. ,
A surface light emitting device, wherein one end of the reflection sheet is arranged so as to cover a gap formed between an edge of the case opening and a light source side edge of the optical sheet from below . 2. The reflection sheet according to claim 1, wherein a length of one end of the reflection sheet protruding inside the case does not exceed a distance between an effective display area of the display device used in combination with the surface light emitting device and an edge of the case opening. Surface emitting device.

Images