JP2002245828A - Flat surface lighting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an attractive surface lighting equipment bigger than a light guide panel. SOLUTION: The flat surface lighting equipment 1 is equipped with a light guide panel 2, a light source 3, a case 4 and a sheet-shaped member. The light guide panel 2 is equipped with a light output face (front face 8) where the light is emitted from, and at least one side of the panel is equipped with a light incident face 9 where the light from the light source is introduced. The sheet-shaped member 5 is arranged on the light output face of the light guide panel 2 and diffuses or converges the emitted light on the output face side. The case 4 is equipped with a concave part 13 where the light guide panel 2, the light source 3 and the sheet-shaped member 5 are installed. Wall faces of the concave part of the case 4 corresponding to the side faces 10 and 11 of the light guide panel 2 excluding the light incident face 9 form inclination wall faces 15 expanding wider from a bottom face 13a of the concave part 13 toward an opening. Leaked light from the side faces 10 and 11 of the light guide panel 2 is positively recovered by reflecting on the inclination wall faces 15 and around 84% of the leaked light is emitted upward from the gap between the light guide panel 2 and the case 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat illuminating device for use in a small liquid crystal display device or the like, which provides a large flat illuminating screen with a small light guide plate, and has a light weight, economical efficiency and excellent workability. It relates to a lighting device.

[0002]

2. Description of the Related Art In a conventional small flat illuminating device, the size of a required screen is equal to the size of a light guide plate. In addition, the size of the flat lighting device is only the sum of the light source component and the light guide plate, and the size of both sides and the size of the light guide plate are in a proportional relationship.

[0003] Further, in the conventional small flat lighting device, a point light source such as a semiconductor light emitting element is generally provided near one side surface of the light guide plate. Then, reflection tapes having high reflection efficiency are attached to the other three side surfaces of the light guide plate, and a reflection sheet having high reflection efficiency is provided below the rear surface of the light guide plate. Thereby, light guided into the light guide plate from the light source is confined in the light guide plate so as not to leak from the side surface and the back surface, and only the front surface portion is opened to emit light, which is equal in size to the front surface portion of the light guide plate. You are getting the screen.

[0004]

In the conventional small flat illuminating device, the required screen size is equal to the size of the light guide plate. In addition, the size of the flat lighting device is only the sum of the light source component and the light guide plate, and the size of both sides and the size of the light guide plate are in a proportional relationship. Therefore, when trying to increase the size of the screen, the size of the light guide plate must be increased. Therefore, there is a problem that it is not possible to reduce the size of the liquid crystal display device using the flat illumination device and to reduce the weight in a large size.

[0005] Conventional small-sized flat lighting devices are generally provided with a point light source such as a semiconductor light emitting element near one side surface of a light guide plate. Then, reflection tapes having high reflection efficiency are attached to the other three side surfaces of the light guide plate, and a reflection sheet having high reflection efficiency is provided below the rear surface of the light guide plate. Thereby, light guided into the light guide plate from the light source is confined in the light guide plate so as not to leak from the side surface and the back surface, and only the front surface portion is opened to emit light, which is equal in size to the front surface portion of the light guide plate. You are getting the screen. For this reason, a screen larger than the size of the light guide plate could not be obtained. In addition, since the reflective tape or the reflective sheet is used, there are problems in economy of materials and the like and workability in attaching these materials and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a planar lighting device capable of obtaining planar light having a uniform luminance distribution without a spot in a size larger than that of a light guide plate. Is to provide.

[0007]

According to a first aspect of the present invention, there is provided a flat lighting device, comprising: a light source;
One side is an entrance surface that takes in light rays from the light source,
A light guide plate from which light rays are emitted from the front surface portion and / or the back surface portion; a sheet member provided on the light guide plate for diffusing or condensing light emitted from the light guide plate; a light source, the light guide plate and the sheet member. It is characterized in that it has a case that has a concave portion for housing, and a wall surface of the concave portion facing the side surface excluding the incident surface portion of the light guide plate has an inclined wall surface that expands from the bottom surface of the concave portion toward the opening.

[0008] The flat lighting device according to claim 1 includes a light source,
At least one side surface is an incident surface portion for receiving a light beam from the light source, and a light guide plate from which a light beam is emitted from a front surface portion and / or a back surface portion is provided on the light guide plate, and diffuses or collects light emitted from the light guide plate. A light-emitting sheet-like member, a light source, a light guide plate, and a concave portion for accommodating the sheet-like member, and a wall surface of the concave portion facing a side surface excluding an incident surface portion of the light guide plate is expanded from the bottom surface of the concave portion toward the opening. Since it has a case with an inclined wall surface, of the light rays existing in the light guide plate,
Light rays leaking from the side surfaces except the incident surface portion are reflected by the inclined wall surface of the concave portion of the case. Then, the reflected light is emitted in a direction substantially toward the surface of the outer periphery excluding the incident surface of the light guide plate. This makes it possible to obtain outgoing light larger than the actual size of the light guide plate.

According to a second aspect of the present invention, in the flat lighting device, the angle between the inclined wall surface of the concave portion and the bottom surface of the concave portion and the opening is 0 °.
It is characterized in that it expands more than 45 °.

[0010] In the flat lighting device according to the second aspect, the inclined wall surface of the concave portion extends in the light guide plate since the angle between the bottom surface of the concave portion and the opening is larger than 0 ° and 45 ° or less. Among the light beams, the light beam having the highest energy among the light beams leaking from the side surface excluding the incident surface portion is vertically reflected by the inclined wall surface of the concave portion of the case. Then, the reflected light is emitted as a bright ray in the direction of the outer peripheral surface except for the incident surface of the light guide plate. This makes it possible to obtain outgoing light larger than the actual size of the light guide plate.

Further, the flat lighting device according to claim 3 is
An end where the front surface portion and / or the back surface portion and the side surface of the light guide plate are connected to the side surface is formed as a surface having a curvature.

According to the third aspect of the present invention, since the end of the light guide plate where the front surface portion and / or the rear surface portion and the side surface are connected is formed by a surface having a curvature, the light guide plate is guided by the boundary surface between the side surfaces. In the case where the edge where the front surface portion or the rear surface portion of the light plate intersects with the side surface is sharp, a bright line generated at a position corresponding to the edge can be suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the flat lighting device according to the present invention, the opening area of the bottom surface of the case recess is set to a size larger than the size of the light exit surface (surface portion) of the light guide plate, and the case recess is opposed to the side surface excluding the incident surface portion of the light guide plate. The wall surface is an inclined wall surface that expands from the bottom surface of the recess toward the opening. The leak light from the side surface of the light guide plate is positively used, and the leak light from the side surface of the light guide plate is reflected by the inclined wall surface of the case recess. From above. Further, a sheet-like member (a diffusion sheet, a prism sheet, or the like) having a substantially case size is provided in the case recess from the upper surface of the light guide plate. Thereby, the light emitted from the light guide plate and the light emitted from the space of the case recess cannot be visually recognized.
As a result, good-looking flat light is obtained with a uniform luminance distribution without unevenness as the whole flat lighting device.

FIG. 1 is a schematic perspective view of a flat lighting device according to the present invention, and FIGS. 2 and 3 are ray trajectories of the flat lighting device.

As shown in FIG. 1, the flat lighting device 1 includes a light guide plate 2, a light source 3, a case 4 and a sheet member 5.

The light guide plate 2 includes an acrylic resin (PMMA) having a refractive index of about 1.4 to 1.7, polycarbonate (PC), polystyrene, polypropylene, polyester, polyolefin, a copolymer of styrene and acrylonitrile, styrene. And a butadiene and a copolymer of styrene and methyl methacrylate.

The light guide plate 2 has a front surface portion 7 for emitting light from the light source 3, a back surface portion 8 opposite to the front surface portion 7,
The front surface 7 and the back surface 8 are composed of side surfaces which intersect at right angles. The side surface includes an incident surface portion 9 that guides a light beam from the light source 3 to the light guide plate 2, an anti-incident surface portion 10 located opposite to the incident surface portion 9, and a side surface 11 following the incident surface portion 9 and the anti-incident surface portion 10.

Although not shown, the surface 7 of the light guide plate 2 is not shown.
And / or the back surface portion 8 is processed to have a convex shape, a concave shape, a groove, or the like. Thus, the light guided into the light guide plate 2 from the light source 3 is reflected or refracted by a convex shape, a concave shape, a groove, or the like, and the light is emitted to the surface portion 7. The back surface 8 of the light guide plate 2 may be subjected to a graining process (a satin finish) or the like. Thereby, light can be scattered by the back surface portion 8 and emitted to the front surface portion 7.

Further, in the light guide plate 2, one side of the incident surface portion 9 for guiding light rays from the light source 3, one side of the opposite incident surface portion 10 located on the opposite side of the incident surface portion 9, the incident surface portion 9 and the opposite incident surface portion 10. The following two side surfaces 11 and the like have a mirror shape different from the front surface portion 7 and the back surface portion 8.

The light introduced from the mirror-shaped entrance surface 9 facing the light source 3 on one side of the light source 3 is incident on the light guide plate 2 at a refraction angle α corresponding to the refractive index n. This incident light has a refraction angle α, which is a normal to the incident surface portion 9, of 0 ≦ | α |
The light travels in the light guide plate 2 within a range satisfying ≦ sin ⁻¹ (1 / n).

Here, the refractive index n of the light guide plate 2 is n = 1.4.
In the case of 9, the refraction angle α is about 42 °. Therefore, the light incident on the light guide plate 2 travels in the light guide plate 2 in this range, and at the boundary between the light guide plate 2 and the refractive index (n = 1) of the air layer, total reflection occurs, and this critical angle Is also approximately β = 42 °.

The end portions of the front surface portion 7 and / or the rear surface portion 8 of the light guide plate 2, that is, the linear portions at the ends where the respective anti-incident surface portions 10 and the side surfaces 11 are connected to the front surface portion 7 and the rear surface portion 8 are formed. Has a chamfer 12 having a predetermined curvature. As a result, all the light beams that have reached the chamfered portion 12 are emitted to the outside of the light guide plate 2, and the light beams that have been emitted once are reflected by the inclined wall surface 15 of the inclined side surface portion 14 of the case 4, which will be described later. Then, when the light enters the light guide plate 2 again, the side surface 1
When the incident angle with respect to 1 (anti-incident surface portion 10) is 90 °,
Most of the light rays are refracted at angles α = 0 to ± 42 inside the light guide plate 2.
Incident in the range of °.

When a part of the light is guided to the end where the side surface 11 (anti-incident surface portion 10) intersects with the front surface portion 7 or the back surface portion 8, the side surface 11 of the light guide plate 2 (anti-incident surface portion 10). If the edge where the front surface portion 7 or the rear surface portion 8 of the light guide plate 2 intersects the side surface 11 (anti-incident surface portion 10) at the boundary surface portion is sharp, a bright line is generated at a position corresponding to this edge. However, in this example, since the end forms the chamfer 12 and does not have a sharp edge, the generation of bright lines can be suppressed and uniform light can be obtained easily.

The light source 3 is formed of a semiconductor light emitting element such as a monochromatic LED such as blue, green, and red, or a white LED or laser. The light source 3 is mounted on an end of the case 4 and emits light to the incident surface 9 of the light guide plate 2. Further, the light source 3 may be a single LED or a plurality of semiconductor light emitting elements such as a single LED emitting light of a single wavelength, an LED mixing light of different wavelengths, and a laser.
Furthermore, the shape of the light source 3 may be a flat surface or a shape with a lens. The light source 3 may be provided with a gap or contact with the light guide plate 2.

The case 4 is molded by mixing a white powder such as barium titanate with an insulating thermoplastic resin material such as a liquid crystal polymer made of modified polyamide, polybutylene terephthalate, aromatic polyester or the like. You. The case 4 may be formed by depositing a metal such as aluminum on the inside where the light guide plate 2 is placed, or by laminating a metal foil. Further, the case 7 may be formed by depositing metal such as aluminum or the like on the inner side where the metal foil or the metal foil is laminated, or may be a film-shaped material or a sheet metal laminated with the metal foil. This improves light reflectivity,
Obtains light-shielding properties.

The case 4 is provided with a concave portion 13 which is open so that the light guide plate 2, the light source 3 and the sheet member 5 can be accommodated therein. The flat bottom surface 13 a of the concave portion 13 has an area substantially equal to the surface area of the light guide plate 2. In addition, on the peripheral wall surface of the concave portion 13, an inclined side wall portion 14 having an inclined wall surface 15 which is expanded from the contour of the bottom surface 13 a toward the opening.
Are formed so as to surround the light guide plate 2. Thereby, the case 4 has a larger spatial surface area than the surface portion 7 of the light guide plate 2 when viewed from the opening of the recess 13.

The recess 13 has a light guide plate 2 on the bottom surface 13a.
It is sufficient that there is a space in the space between the wall surface and the incident surface 9 where the light source 3 can be mounted facing the incident surface 9 of the light guide plate 2. Therefore, the wall surface of the concave portion 13 facing the incident surface portion 9 of the light guide plate 2 does not need to be the inclined wall surface 15.

The inclined wall surface 15 of the case 4 extends from the contour position of the back surface 8 of the light guide plate 2 to a virtual extension line of the back surface 8 (FIG. 2).
(The LL line shown by the one-dot chain line) is about 45 °. That is, the inclined wall surface 15 of the case 4 is inclined from the bottom surface 13a of the concave portion 13 toward the opening,
The inclination angle with the bottom surface 13a is about 45 °.
As a result, light emitted from the side surface 11 (anti-incident surface portion 10) of the light guide plate 2 is transmitted to the side surface 11 of the light guide plate 2 (anti-incident surface portion 10).
The light is reflected and deflected above the space defined by the gap and the inclined wall 15.

Further, the case 4 is provided with a sheet receiving portion 16 in which an upper portion is cut off in a band shape from the height position of the surface portion 7 of the light guide plate 2 on an upper portion of the inclined side surface portion 14 on the side of the inclined wall surface 15. . In the sheet receiving portion 16, a sheet-like member 5 formed of a diffusion sheet or a prism sheet placed on the upper surface portion 7 of the light guide plate 2 is fixed in position, and stores the periphery of the contour of the sheet-like member 5.

The flat lighting device configured as described above
As shown in FIG. 3, the housing 4 is mounted on a base 21 made of an outer frame such as a thermoplastic synthetic resin or a substrate made of a glass epoxy resin. It has a portion S. Accordingly, when the flat lighting device of the present invention is mounted on a liquid crystal display device or the like, the space portion S of the case 4 can be effectively used as a mounting space for housing electronic components. As a result, the size of a liquid crystal display device or the like using the flat lighting device can be reduced.

Here, the trajectory of light rays between the light guide plate 2 and the case 4 will be described. The light beam incident from the incident surface 9 is
Light within 0 to ± 42 ° exists in the light guide plate 2. The 0- + 42 ° ray traveling in the direction of the front surface portion 7 is totally reflected by the front surface portion 7 and travels in the direction of the rear surface portion 8. Then, the side surface 11 is separated from the incident surface portion 9 while performing total reflection on the back surface portion 8 again.
It proceeds in the (anti-incident surface section 10) direction. And among these light rays, for example, the light ray totally reflected by the surface portion 7 is the side face 1.
1 (anti-incident surface portion 10), when a 42 ° ray L0 totally reflected by the surface portion 7 exits from the side surface 11 (anti-incident surface portion 10) as shown in FIG. Then, the light is reflected by the inclined wall surface 15 of the inclined side surface portion 14. Then, the reflected light enters the light guide plate 2 again from the side surface 11 (anti-incident surface portion 10), and is emitted from the surface portion 7.

As described above, 0 to ± 42 in the light guide plate 2
Of the light in the ° range, a light beam having an incident angle α on the side surface 11 (anti-incident surface portion 10) of approximately 28.22 ° is refracted by the air layer outside the light guide plate 2 to have an emission angle β of approximately 45 °. . When the angle γ that forms the inclined wall surface 15 of the inclined side surface portion 14 with the virtual extension line of the rear surface portion 8 from the contour position of the rear surface portion 8 of the light guide plate 2 is 45 °, the light source 3 and the inclined wall surface 15 intersect at a right angle. , Are returned to the light guide plate 2 again. Thus, the incident angle α with respect to the side surface 11 (anti-incident surface portion 10) is approximately 42 ° to 28.3.
Light rays up to 3 ° are returned to the light guide plate 2 again. On the other hand, the light beam of approximately 28.22 ° or less and the total light beam totally reflected from the back surface portion 8 are emitted from the side surface 11 (anti-incident surface portion 10). Further, the light beam having a angle of approximately 28.33 ° or less is reflected by the inclined wall surface 15 of the inclined side surface portion 14 and travels upward.
As shown in FIG. 3, in particular, the side surface 11 (anti-incident surface portion 10)
The light beam L1 traveling at right angles to is reflected at 45 ° on the inclined wall surface 15 having an inclination of 45 ° without being refracted. Then, the reflected light beam L11 travels in the vertical direction (perpendicular to the virtual plane parallel to the surface portion 7).

Further, for example, even in the case of a light ray of about 20 ° in the light guide plate 2, total reflection is repeated on the front surface portion 7 and the back surface portion 8, and the light is totally reflected on the front surface portion 7 and proceeds toward the back surface portion 8. Then, the light beam L2 directed to the side surface 11 (anti-incident surface portion 10)
Indicates that the incident angle α1 is 2 with respect to the side surface 11 (anti-incident surface portion 10).
At about 0 °, the light is refracted by the air layer to a refraction angle β1 of about 30.538. The refracted light beam L22 is reflected by the inclined wall surface 15 having an inclination of 45 °, and the reflected light beam L23
The light is slightly emitted above the light guide plate 2.

Similarly, the light beam L3 totally reflected by the back surface portion 8 and traveling toward the front surface portion 7 toward the side surface 11 (anti-incident surface portion 10) is incident on the side surface 11 (anti-incident surface portion 10) at an incident angle α1.
Is about 20 °, the refraction angle β1 = 30.338 in the air layer
Refracted to the extent. The refracted light beam L32 is reflected by the inclined wall surface 15 having an inclination of 45 °, and the reflected light beam L32
The light 33 is slightly emitted upward and outward of the light guide plate 2.

Therefore, of the light rays in the light guide plate 2, the light rays of about 28.33 ° or more are used for the side surface 11 (anti-incident surface portion 10).
All the light rays except the light rays that travel downward from are emitted upward. The light amount of the light beam emitted upward corresponds to approximately 84% of the light amount emitted from the side surface 11 (anti-incident surface portion 10). Therefore, the light emitted from the surface portion 7 of the light guide plate 2 and the side surface 11
There is not much difference from the outgoing light utilizing the leaked light from the (anti-incident surface portion 10), and the light is emitted above the surface portion 7 of the light guide plate 2. Then, the surface portion 7 of the light guide plate 2 and the inclined wall surface 1
By providing a sheet-like member 5 such as a diffusion sheet or a prism sheet so as to cover 5, there is no occurrence of unevenness in luminance,
Good-looking emitted light can be obtained.

As described above, the side surface 11 excluding the incident surface portion 9
The wall surface of the concave portion 13 of the case 4 corresponding to the (anti-incident surface portion 10) is formed such that the angle between the contour position of the rear surface portion 8 of the light guide plate 2 and the virtual extension line of the rear surface portion 8 is larger than 0 ° and 45 ° or less.
Since the inclined wall surface 15 is widened outward toward the opening 3, the energy among the light beams leaking from the side surface 11 (anti-incident surface portion 10) excluding the incident surface portion 9 among the light beams existing in the light guide plate 2 has the highest energy. The strong light beam is reflected in the vertical direction by the inclined wall surface 15 of the inclined side surface portion 14. Then, the reflected light is emitted as a bright light in the direction of the outer peripheral surface portion 8 excluding the incident surface portion 9 of the light guide plate 2, so that an emitted light larger than the actual size of the light guide plate 2 can be obtained.

The sheet member 5 is made of, for example, a diffusion sheet or a prism sheet, and is provided above the surface 7 of the light guide plate 2. If a diffusion sheet is used as the sheet member 5, it is possible to diffuse light emitted from the surface portion 7 of the light guide plate 2 and light emitted from the space between the light guide plate 2 and the wall surface 15 of the inclined side surface portion 13 of the case 4. it can. If a prism sheet is used as the sheet member 5, light emitted from the surface portion 7 of the light guide plate 2, and light emitted from the space between the light guide plate 2 and the inclined wall surface 15 of the inclined side surface portion 14 of the case 4 are collected. Can light. This makes it possible to adjust the luminance distribution and the like from the emission surface of the flat illumination device of the present invention, and obtain uniform emission light without spots.

The case 4 itself is molded by mixing a white powder for improving the light reflectivity, but the reflectivity is further improved, and the light leaking from the back surface 8 of the light guide plate 2 is again reflected on the light guide plate 2.
Although not shown here, a reflector may be provided between the light guide plate 2 and the case 4 in order to return to. This reflector is made of a thermoplastic resin sheet provided with a metal lock made of aluminum or the like or laminated with a metal foil, a sheet-shaped metal, or a film made of these. The reflector reflects or diffusely reflects the light from the light source 3 leaked from the light guide plate 2 or the light emitted from the rear surface portion 8 and makes the light enter the light guide plate 2 again.

As described above, in the flat lighting device of the present invention,
A concave portion that is larger than the light guide plate is provided in the case,
The wall surface of the concave portion facing the side surface excluding the incident end surface of the light guide plate is an inclined wall surface, and light leaking from the side surface of the light guide plate is emitted toward the opening direction of the concave portion by the inclined wall surface. Further, a sheet-like member made of a diffusion sheet or a prism sheet is placed so as to cover the surface portion and the inclined wall surface of the light guide plate. Thereby, about 84% of the leaked light from the side surface of the light guide plate is emitted upward from the space between the light guide plate and the case, and a flat illumination device that emits plane light having a size larger than the size of the light guide plate is obtained. be able to.

[0040]

As described above, in the flat lighting device according to the first aspect, the light source and at least one side surface are formed as the incident surface portion for receiving the light beam from the light source, and the light beam is emitted from the front surface portion and / or the rear surface portion. A light guide plate, a sheet member provided on the light guide plate, for diffusing or condensing light emitted from the light guide plate, and a concave portion for housing the light source, the light guide plate, and the sheet member. The case, in which the wall surface of the concave portion facing the side surface excluding the surface portion is an inclined wall surface that expands from the bottom surface of the concave portion toward the opening, so that of the light beams existing in the light guide plate, the side surface excluding the incident surface portion The light leaked from the case is reflected by the inclined wall surface of the concave portion of the case. Then, the reflected light is emitted in a direction substantially toward the surface of the outer periphery excluding the incident surface of the light guide plate. This makes it possible to obtain outgoing light larger than the actual size of the light guide plate. In addition, by also using a sheet-like member such as a diffusion sheet or a prism sheet, it is possible to obtain a light and large flat illumination device without spots.

Further, in the flat lighting device according to the second aspect, the angle between the bottom surface of the concave portion and the opening is expanded to be larger than 0 ° and 45 ° or less. Among the light beams leaking from the side surfaces excluding the incident surface portion, the light beam having the highest energy is vertically reflected by the inclined wall surface of the concave portion of the case. Then, the reflected light is emitted as a bright ray in the direction of the outer peripheral surface except for the incident surface of the light guide plate. This makes it possible to obtain outgoing light larger than the actual size of the light guide plate. In addition, by also using a sheet-like member such as a diffusion sheet or a prism sheet, it is possible to obtain a light and large flat illumination device without spots. Moreover, when the flat lighting device is mounted on a substrate or the like, the space below the inclined wall surface can be effectively used as a mounting space for electronic components, and the size of a liquid crystal display device or the like using the flat lighting device can be reduced. .

Further, the flat lighting device according to claim 3 is
Since the end connecting the front surface portion and / or the back surface portion and the side surface of the light guide plate is formed with a curved surface, the edge where the front surface portion or the back surface portion of the light guide plate intersects the side surface at the boundary surface of the light guide plate at the side surface. Is sharp, a bright line generated at a position corresponding to the edge can be suppressed. This makes it possible to provide a flat lighting device that can provide easy-to-see and uniform light.

[Brief description of the drawings]

FIG. 1 is a schematic perspective configuration diagram of a flat lighting device according to the present invention.

FIG. 2 is a ray trajectory diagram of the flat lighting device according to the present invention.

FIG. 3 is a ray trajectory diagram of the flat lighting device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Planar illumination device, 2 ... Light guide plate, 3 ... Light source, 4 ... Case, 5 ... Sheet-shaped member which consists of a diffusion sheet or a prism sheet, 7 ... Front surface part, 8 ... Back surface part, 9 ... Incident surface part, 10 ...
Anti-incident surface part, 11 ... side surface, 12 ... end (chamfer), 13 ...
Recessed part, 13a bottom surface, 14 inclined side surface part, 15 inclined wall surface, 16 sheet receiving part, 21 base material, α refraction angle, α1
... incident angle, β ... critical angle, β1 ... outgoing angle, γ ... angle between the inclined wall surface and the virtual extension line on the back surface of the light guide plate, n ... refractive index, L
0, L1, L2, L3, L01, L11, L22, L2
3, L32, L33: light ray, S: spatial part.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // F21Y 101: 02 F21Y 101: 02

Claims (3)

[Claims] A light source, a light guide plate having at least one side surface serving as an incident surface portion for taking in a light beam from the light source, and a light guide plate for emitting the light beam from a front surface portion and / or a back surface portion; and a light guide plate provided on the light guide plate. A sheet-like member for diffusing or condensing light emitted from the light guide plate, a concave portion for accommodating the light source, the light guide plate, and the sheet-like member, and facing a side surface of the light guide plate excluding the incident surface portion. A flat illumination device, comprising: a case in which a wall surface of the concave portion is an inclined wall surface that expands from a bottom surface of the concave portion toward an opening. 2. The flat lighting device according to claim 1, wherein an angle between the bottom surface of the concave portion and the opening of the concave wall surface is larger than 0 ° and 45 ° or less. 3. The light guide plate according to claim 1, wherein an end where the front surface and / or the back surface is connected to the side surface has a curved surface.
A flat lighting device as described in the above.