JPH05107542A - Backlight unit for display device - Google Patents

Abstract

PURPOSE:To provide a backlight unit whose entire surface is uniformly bright. CONSTITUTION:In a display device obtained by mounting a display board part on a backlight consisting of light sources 15 mounted on the inner sides of both side walls of a case 11 whose upper part is opened, a plate-like light transmission plate 20 which is mounted between the light sources 15 in a state where its back surface tightly contacts to the base of the case 11, and on which the emitted light from the light source 15 is made incident from right and left side surfaces 21, and a diffusion plate 14 mounted to tightly contact to the surface of the light transmission plate 20; inverted V-shaped recessed part 25 is provided in the center part of the back surface of the light transmission plate 20 and rugged pattern 20a is formed all over the back surface of the plate 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit provided on the back surface of a liquid crystal display panel or the like.

In a recent communication terminal, an operation panel portion is provided on the surface of the housing 2 as shown in FIG. 3, and a telephone number of a call destination is displayed above the operation panel portion or a message of a sender is displayed. There is a device provided with a display device 1 for displaying, for example.

In the display device as described above, as shown in FIG. 4, a liquid crystal display plate 3 is incorporated on the front surface of a housing 2, and a backlight unit 5 is mounted on the back surface side of the liquid crystal display plate 3 to display a liquid crystal display. The back side of the plate 3 is brightened so that characters and the like displayed at night can be clearly read.

[0004]

2. Description of the Related Art FIG. 5 is a diagram of a conventional backlight unit, (A) is a perspective view, (B) is a cross-sectional view, and FIG. 6 is a cross-sectional view of essential parts of a conventional example.

In FIGS. 5 and 6, the backlight unit 5 includes a channel-shaped case 11 made of white synthetic resin or the like and having an upper opening, and a light source (for example, an LED) 15 mounted inside both side walls of the case 11. , A flat light guide plate 13 mounted between the light sources 15 so that the back surface is in close contact with the case bottom plate 12.
And a diffusing plate 14 made of a white film that is closely attached to the surface of the light guide plate 13. The light guide plate 13
Is a flat plate made of a transparent acrylic resin or the like.

In the backlight unit 5 constructed as described above, the light emitted from the respective light sources 15 by expanding in a conical shape enters the light guide plate 13 from the left and right side surfaces. Then, the light incident on the upper half of the side surface of the light guide plate 13 is refracted at the side surface, goes straight through the light guide plate 13 and enters the diffusion plate 14, and the diffusion plate 14
It diffuses inside to lighten the diffuser plate 14.

On the other hand, the light incident on the lower half of the side surface of the light guide plate 13 is refracted at the side surface and goes straight inside the light guide plate 13, and a part of the light is reflected by the back surface of the light guide plate 13 so as to spread obliquely upward. To do. The other part of the light passes through the back surface of the light guide plate 13, is reflected by the inner surface of the case bottom plate 12, is incident on the light guide plate 13 again, and goes straight through the light guide plate 13 so as to spread obliquely upward, and diffuser plate. It is incident on 14 and diffuses to make the diffusion plate 14 bright.

[0008]

By the way, as shown in FIG. 6, most of the light incident on the light guide plate 13 is projected on the front surface or the back surface near the side surface of the light guide plate. Then, a part of the light is projected near the central portion of the front surface or the back surface of the light guide plate 13.

Therefore, in the conventional backlight unit, the vicinity of the light source is bright, the central part of the two-thirds or more of the surface becomes dark, and the characters and the like displayed on the central part of the liquid crystal display plate become unclear. There was a problem.

The present invention has been made in view of the above points, and an object thereof is to provide a backlight unit in which the entire surface is uniformly bright.

[0011]

In order to achieve the above object, the present invention, as illustrated in FIG. 1, has a light source 15 mounted on the inside of both side walls of a case 11 having an upper opening, and a back surface of the case 11. Installed between the light sources 15 in close contact with the bottom of the
A plate-shaped light guide plate in which the emitted light of 15 enters from the left and right side surfaces 21
In a display device in which a display plate part is mounted on a backlight composed of a light guide plate 20 and a diffuser plate 14 that is closely attached to the front surface of the light guide plate 20, an inverted V-shaped recess 25 is formed in the center of the back surface of the light guide plate 20. The light guide plate 20 is provided with an uneven pattern 20a on the entire back surface thereof.

Alternatively, as shown in FIG. 2, an inverted V-shaped recess 25 is provided in the center of the back surface of the light guide plate 20, and
A concave-convex pattern 20a is provided on the entire back surface of 20, and the inverted V-shaped concave portion 25 is closely fitted to the inverted V-shaped convex portion 125 provided in the central portion of the case bottom plate 12.

[0013]

According to the present invention, by providing an uneven pattern on the back surface of the light guide plate and further providing an inverted V-shaped recess on the light guide plate, most of the light traveling near the center plane of the light guide plate is guided. The light is reflected by the inverted V-shaped slope at the center of the. Therefore, there is almost no useless light passing through the light guide plate in the left-right direction and having no illumination effect, and the central portion of the diffusion plate 14 is uniformly brightened in the same manner as in the vicinity of the light source.

Further, the case bottom plate is provided with an inverted V-shaped convex portion which is in close contact with the inverted V-shaped concave portion. Therefore, the light transmitted through the sloped surface of the inverted V-shaped concave portion without being reflected is reflected by the sloped surface of the inverted V-shaped convex portion of the case bottom plate and enters the light guide plate again. Therefore, the lighting efficiency is further improved.

[0015]

The present invention will be described in detail with reference to the drawings. The same reference numerals denote the same objects throughout the drawings. FIG. 1 is a diagram of an embodiment of the present invention, (A) is a full sectional view,
FIG. 2B is a sectional view of a main part, and FIG. 2 is a sectional view of the main part of another embodiment of the present invention.

In FIG. 1, the backlight unit 10
Is a channel-shaped case 11 made of white synthetic resin (for example, ABS) with an open top, a light source (for example, an LED) 15 mounted on the inside of both side walls of the case 11, and a back surface so as to be in close contact with the case bottom plate 12. The light guide plate 20 is mounted between the light sources 15, and the diffuser plate 14 made of a white film is closely attached to the surface of the light guide plate 20.

The light guide plate 20 is a flat plate made of transparent acrylic resin or the like, and an inverted V-shaped recess 25 having an obtuse side view is provided in the center of the back surface of the light guide plate 20. The depth of the inverted V-shaped recess 25 is about 3/4 of the thickness of the light guide plate 20.

Further, a fine uneven pattern 20a is provided on the entire back surface of the light guide plate 20. Therefore, in the backlight unit 10 configured as described above, as shown in FIG. 1 (B), of the light emitted from the respective light sources 15 by expanding in a conical shape, the side surface 21 emits light. Almost half of the light that has entered the upper half reaches the vicinity of the central portion on the surface side of the light guide plate 20, enters the diffusion plate 14, and diffuses in the diffusion plate 14 to make the diffusion plate 14 bright.

Almost half of the light incident on the lower half of the side surface 21 of the light guide plate 20 is projected on the back surface of the light guide plate 20 in the vicinity of the light source 15 and is reflected by the uneven pattern 20a so as to be diffused obliquely upward, Alternatively, it is reflected obliquely upward on the surface of the case bottom plate 12 to brighten the vicinity of the left and right ends of the diffusion plate 14.

On the other hand, most of the light incident near the center of the side surface 21 is projected on the slope of the inverted V-shaped recess 25, and the uneven pattern 20 is formed.
It is reflected by a so that it diffuses obliquely upward, and the diffuser plate 14
The central part of the diffuser plate 14 is made bright by being incident on the central part.

That is, the entire surface of the backlight unit becomes brighter almost uniformly as compared with the conventional one. In FIG. 2, the case bottom plate 12 is provided with an inverted V-shaped convex portion 125 that fits into the inverted V-shaped concave portion 25 of the light guide plate 20.

Therefore, the light transmitted through the sloped surface of the inverted V-shaped concave portion 25 without being reflected thereon is reflected by the sloped surface of the inverted V-shaped convex portion 125 and enters the light guide plate 20 again. Therefore, the illumination efficiency is further improved over that shown in FIG.

[0023]

As described above, according to the present invention, in the backlight unit to be mounted on the back surface side of the liquid crystal display plate or the like, the light guide plate is provided with the concavo-convex pattern and the inverted V-shaped recess is provided. More light reaches near the center of the diffuser plate, the entire surface of the backlight unit becomes brighter almost uniformly, and the characters displayed on the liquid crystal display plate become clearer. Have.

[Brief description of drawings]

FIG. 1 is a diagram of an embodiment of the present invention, in which (A) is a complete cross-sectional view and (B) is a cross-sectional view of a main part.

FIG. 2 is a cross-sectional view showing the main points of another embodiment of the present invention.

FIG. 3 is a perspective view of a communication terminal.

FIG. 4 is a sectional view of a display device.

FIG. 5 is a view of a conventional example, (A) is a perspective view, and (B) is a sectional view.

[Fig. 6] Cross-sectional view of a key part of a conventional example

[Explanation of symbols]

1 display device, 2 housings, 3
LCD panel, 5,10 backlight unit, 11
Case, 12 case bottom plate, 13,20 light guide plate,
14 diffuser, 15 light source,
20a uneven pattern, 21 sides,
25 reverse V-shaped concave, 125 reverse V-shaped convex,

Claims (2)

[Claims] 1. A light source (15) to be mounted inside both side walls of a case (11) having an upper opening, and a light source (15) mounted so that its back surface is in close contact with the bottom surface of the case (11). , A light guide plate (2) having a flat plate shape into which light emitted from the light source (15) enters from the left and right side surfaces (21).
0) and a diffuser plate (1) that is closely attached to the surface of the light guide plate (20).
In a display device in which a display plate portion is mounted on a backlight consisting of 4), an inverted V-shaped recess (25) is provided in the center of the back surface of the light guide plate (20), and Uneven pattern (20a) on the entire back surface
A backlight unit for a display device, which is provided with. 2. The display device according to claim 1, wherein an inverted V-shaped recess (25) is provided in a central portion of the back surface of the light guide plate (20), and an uneven pattern is formed on the entire back surface of the light guide plate (20). (20a)
And a reverse V-shaped concave portion (25) closely fitted to a reverse V-shaped convex portion (125) provided in the central portion of the case bottom plate (12). .