JPH08262233A - Illumination device - Google Patents

Abstract

PURPOSE: To provide an illumination device which is designed mainly to enhance luminance and to suppress unequal luminance and is effective for control of a visual field angle. CONSTITUTION: This illumination device is formed by arranging, for example, U-shaped fluorescent lamp tubes 21, which are approximately U-shaped light sources along the three sides of a rectangular flat planar light transmission plate 20, arranging a reflection plate 24 covering the other one side and rear surface of this light transmission plate 20 and arranging a diffusion plate on the front surface. A reflection mirror member (or light diffusion member) 30 formed to a shape extending from the other one side of the light transmission plate 20 facing the reflection plate 24 toward both ends of the opposite side is embedded and disposed in the light transmission plate 20. The light transmission plate 20 is segmented by this reflection mirror member 30 to the three parts corresponding to the U-shaped fluorescent lamp tubes 21. As a result, the luminance is made uniform over the entire area of the light transmission plate 20, by which the unequal luminance is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (LC
The present invention relates to a lighting device for making a display on a display panel of D) clear.

[0002]

2. Description of the Related Art LCDs used for TVs, OA equipment terminals, etc.
Many of them are equipped with a backlight that uniformly illuminates the display panel from the rear in order to provide a clear display. The backlight is classified into a direct type and an edge light type according to its method. Since the direct type has a difficulty in thinning, the edge light type, which is thin and obtains uniform brightness, is currently the mainstream. These edge-light type lighting devices are basically
The light diffusion member and an inverter cathode fluorescent tube such as a cold cathode tube or a hot cathode tube are provided as light sources. As the light diffusing member, a rectangular flat plate-shaped light guide plate made of a transparent acrylic resin plate or the like is provided, and a reflection sheet (or a reflection plate) arranged in parallel with some of the four sides of the light guide plate,
It comprises a diffusion plate (not shown) arranged on the front surface side of the light guide plate. 8 to 12 are front views showing various examples of conventional edge-light type illumination devices.
In FIG. 8, the rectangular light guide plate 1 faces in parallel with one end face.
The cathode fluorescent tube 2 formed of a straight tube is connected to the inverter 3 and arranged, and the reflecting plate 4 is arranged along the other three sides of the driving plate 1. In FIG. 9, two intuitive cathode fluorescent tubes 2 and 2 are arranged on opposite sides, and reflectors 5 and 5 are arranged on the other two sides. In FIG. 10, an L-shaped cathode fluorescent tube 6 is arranged along two adjacent sides which are orthogonal to each other, and an L-shaped reflection plate 7 is arranged on the other two sides. Figure 11 shows U along three sides
A cathode-shaped fluorescent tube 8 having a letter shape is arranged, and the reflector 5 is provided on the other side.
Has been arranged. And FIG. 12 is configured by arranging the above two L-shaped cathode fluorescent tubes 9 along all four sides.

[0003]

By the way, as seen in these examples of various illuminating devices, a rectangular flat plate-shaped light guide plate 1 is used.
In order to make the luminance uniform and prevent the occurrence of luminance unevenness, it is a very common method to arrange the cathode fluorescent tubes along more than one side of the light guide plate 1 as described above. Is. When the light sources are arranged on all three sides or all four sides as in the apparatus shown in FIGS. 11 and 12, it is advantageous in terms of increasing brightness and uneven brightness. On the other hand, when the viewing angle of the liquid crystal panel is set effectively, it tends to be disadvantageous even more efficiently than that of each of the devices shown in FIGS. Therefore,
At present, a structure in which a light source is arranged on one side or two sides as in each of the devices shown in FIGS. Therefore, it is an object of the present invention to provide an illuminating device which is effective in view angle control, mainly in terms of increasing the brightness and suppressing the uneven brightness.

[0004]

In order to achieve the above object, an illumination device according to the present invention has a substantially U-shaped light source arranged along three sides of a rectangular flat light guide plate, and another A reflecting mirror having one side and a back surface and a reflecting plate disposed on the front surface, and a diffusing plate disposed on the front surface. The reflecting mirror has a shape extending from the other side of the light guide plate facing the reflecting plate toward both ends of the opposite side. A member or a light diffusion member is provided on the light guide plate, and the light guide plate is divided into three parts corresponding to the light source by the reflection mirror member or the light diffusion member. Further, in the illuminating device of the present invention, the reflecting mirror member or the light diffusing member extends from the other side of the light guide plate toward the opposite side, and is branched in the middle toward both ends of the opposite side. Can be formed into a shape. Further, in the illuminating device of the present invention, the cross-sectional shape of the reflecting mirror member or the light diffusing member can be any of a flat plate shape, a mountain shape, and a semicircular shape, and the height thereof is the plate thickness of the light guide plate. It is made smaller and is buried.

[0005]

The natural light is emitted from the light source having a substantially U-shape to the light guide plate from the three sides thereof. The light from the light source is diffused and reflected inside the light guide plate, and is emitted uniformly from the surface of the light guide plate by being reflected by the reflecting mirror member or the light diffusing member. Since the light guide plate is divided into three parts by the reflecting mirror member or the light diffusing member, the light from the three side directions is processed in about three sections and is efficiently reflected so that the diffuser plate is removed from the surface of the light guide plate. It passes and is ejected. Therefore, the viewing angle can be easily set in one direction. By making the height of the reflecting mirror member or the light diffusing member smaller than the plate thickness of the light guide plate, the light of the three sections is reflected by the corresponding reflecting mirror member or the light diffusing member, respectively, but it corresponds to the light. There are also those that pass through the reflecting mirror member or the light diffusing member and pass to other sections, and such light is reflected and emitted in other sections,
Due to these effects, the directionality of light can be organized in three categories, and at the same time, the light source light can be reflected and emitted uniformly over the entire light guide plate, and uniform brightness can be secured. The cross-sectional shape of the reflector member or the light diffusion member may be flat, mountain-shaped, or semicircular, and if the plate is flat, incident light may be totally reflected. It is preferable to have an appropriate slope gradient and curved surface.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An edge light type backlight device as an embodiment of the illuminating device according to the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing an example of an LCD equipped with the edge light type backlight device of the embodiment. FIG. 2 is a perspective view of the assembly. The edge light type backlight device 10 is housed inside a housing case 11, and illuminates the liquid crystal panel 12 on the front side from behind.

As shown in the front view of FIG. 3, the edge light type backlight device 10 of the embodiment has a light guide plate 20 in the shape of a rectangular flat plate made of a transparent acrylic resin plate or the like, along the end faces of the three sides. A substantially U-shaped fluorescent lamp tube 21, which is a light source, is connected to the inverter 22 by a wiring 23. On the other side 20a of the light guide plate 20, a reflection plate 24 (a sheet may be used, or a film may be formed as a reflection layer) in parallel with the end face.
In addition, as shown in each of FIG.
A reflector plate 26 is provided on the back surface 25 side of 0, and this may be integrated with the reflector plate 24 on the one side 20a side.
A diffusion plate 28 facing the liquid crystal panel 12 shown in FIG. 1 from behind is arranged on the surface 26 side of the light guide plate 20.
Further, as shown in FIG. 3, the U-shaped fluorescent lamp tube 21 has a reflection sheet 29 arranged as a reflector from the outside.

FIG. 4 is a side sectional view of the apparatus 10. The right side of the drawing is the viewing angle direction of the liquid crystal panel 12 as indicated by arrow A, the diffusion plate 28 on the light guide plate 20 side is faced, and the left side is the above. The reflection plate 26 is arranged. That is, as shown in FIGS. 4 and 3, the light guide plate 20 is provided with the reflecting mirror member (or light diffusing member) 30, which is the essential member of the present invention, buried therein. The reflection mirror member 30 can be embedded in the acrylic resin light guide plate 20 by being integrated with the light guide plate 20 by, for example, insert molding. As in the illustrated example, the reflecting mirror member 30 is formed in a substantially Y-shape as a whole, and a trunk portion 31 extending from the central portion of the other side 20a of the light guide plate 20 toward the facing side 20b,
It is substantially Y-shaped and is composed of branch portions 32 and 32 that branch toward both ends of the opposite side 20b from the middle. As a result, the light guide plate 20 is divided into three parts 20A, 20B, 20C corresponding to the U-shaped fluorescent lamp tube 21 in three directions. However, as described in the gist of the present invention, even if the reflecting mirror member 30 is not substantially Y-shaped, if the light guide plate 20 can be divided into three parts, it is branched from one side 20a directly to both ends of the opposite side 20 in a V-shape. You can

5 to 7 show three different forms depending on the side sectional shape of the reflecting mirror member 30, all of which are indicated by I in FIG.
It is a side sectional view of the above-mentioned main part 31 and branching parts 32 and 32 by the -I arrow line. 5 has a flat plate shape having reflecting surfaces 33, 33 on both sides, and FIG. 6 has a mountain shape in which the reflecting surfaces 34, 34 on both sides are inclined at an angle θ. In the case of, the curved front surface is a semicircular shape with the reflecting surface 35. The height h of any of these cross-sectional shapes is smaller than the plate thickness t of the light guide plate 20.
This is because the height h of the reflecting mirror member 30 is made equal to the plate thickness t of the light guide plate 20, so that the light guide plate 20 cannot be completely divided into three parts. Two
This is because light emitted from one direction to three directions can pass through and cross each other at these three light guide plate portions 20A, 20B, and 20C.

With the above construction, the following effects can be obtained in the embodiment. As shown in FIG. 5, when the light of the fluorescent lamp tube 21 is incident in the directions of the three sides of the light guide plate 20, in the three light guide plate portions 20A, 20B, and 20C, the basic portion 31 and the branch portion 32 of the reflecting mirror member 30. , 32, so that
The parallel light 40 and the like are diffused by each section, reflected by the reflection surface 33 of the trunk portion 31 and the branch portions 32, 32, and emitted from the surface 26 of the light guide plate 20 as reflected light 41.
That is, since the light guide plate 20 can be considered to be divided into three pieces, the light source light is efficiently diffused and reflected by each, and the light source light can be effectively used without being exhausted, and the brightness of the light guide plate 20 is also high. It becomes uniform over the entire area and the required brightness can be secured. In the light of the fluorescent lamp tube 21, the reflecting mirror member 30
There is also a ray 42 that passes through the main portion 31 and the branching portions 32, 32 and enters another section, but is eventually reflected by the other section or is reflected by the reflection plate 25 arranged on the back surface 25 of the light guide plate 20, Since it is ejected from 26, it is not invalidated.

By the way, as shown in FIG.
When the cross-sectional shape is flat, when the light from the fluorescent lamp tube 21 is parallel light traveling in a portion near the back surface 25 of the light guide plate, the light is totally reflected by the reflecting surface 33 of the reflecting mirror member 30 as it is. There is a concern that it becomes reflected light 42 and is not emitted from the surface 26 and is not used. In that case, since the reflecting surface 34 and the reflecting surface 35 have the inclination angle and the curved surface like the reflecting mirror member 30 having the cross-sectional shape of FIGS. 6 and 7, the reflected lights 45 and 47 become total reflection. There is an advantage that can be almost avoided.

As described above, in one light guide plate 20, the light in the three directions from the fluorescent lamp tube 21 can be diffused and reflected by the three sections substantially independently, and the light emitted from the entire area of the light guide plate 20 can be reflected. Light, that is, incident light on the liquid crystal panel 12, becomes easier to grasp the light direction thereof, and the control of the viewing angle becomes easier. Further, since the light source plate 20 can minimize the light source light that is lost, the function of the fluorescent lamp tube 21 that emits light from three directions in a substantially U-shape is fully utilized to secure a sufficient amount of light and uniform brightness. It is effective to prevent uneven brightness and uneven brightness. As a result, it is possible to uniformly illuminate the liquid crystal panel of the LCD and the like, and a clear display can be performed on the liquid crystal panel.

[0013]

As described above, in the lighting device according to the present invention, the light guide plate is the reflecting mirror member (or the light diffusing member).
Since it is divided into three parts by each, and it is possible to process light by diffusion and reflection in each section, a substantially U-shaped light source that emits light from three directions can be used, and in combination with securing a sufficient amount of light, It is effective for uniforming the luminance and preventing the luminance unevenness, and can overcome the conventional problem that the view angle control by the light source light from three directions is complicated.

[Brief description of drawings]

FIG. 1 is an LC showing an embodiment in which an edge light type backlight device is mounted as an embodiment of an illuminating device according to the present invention.
FIG.

FIG. 2 is an assembled perspective view of the LCD.

FIG. 3 is a front view of the edge light type backlight device according to the embodiment.

FIG. 4 is a side sectional view of an edge light type backlight device according to an embodiment.

FIG. 5 is a side cross-sectional view showing an example of an embodiment according to the cross-sectional shape of the reflecting mirror member equipped in the edge light type backlight device of the embodiment.

FIG. 6 is a side sectional view showing another example of the form depending on the sectional shape of the reflecting mirror member.

FIG. 7 is a side sectional view showing another example of the form depending on the sectional shape of the reflecting mirror member.

FIG. 8 is a front view showing a form example of a conventional edge light type backlight device.

FIG. 9 is a front view showing an example of a form of a conventional edge light type backlight device.

FIG. 10 is a front view showing an example of a form of a conventional edge light type backlight device.

FIG. 11 is a front view showing an example of a form of a conventional edge light type backlight device.

FIG. 12 is a front view showing an example of a form of a conventional edge light type backlight device.

[Explanation of symbols]

 10 Edge Light Type Backlight Device (Illumination Device) 12 LCD Liquid Crystal Panel 20 Light Guide Plate 20A, 20B, 20C 3 Sections of Light Guide Plate 21 C-shaped Fluorescent Lamp Tube 24, 27 Reflector 28 Diffuser 30 Reflector Member 31 Y-shaped Base part 32 of reflecting mirror member Branch part 34, 34, 35 Reflective surface

Claims (3)

[Claims] 1. A substantially U-shaped light source is arranged along three sides of a rectangular flat plate-shaped light guide plate, a reflection plate is arranged so as to cover the other side of the light guide plate and the back surface, and a diffusion plate is arranged on the front surface. In the lighting device, a reflecting mirror member or a light diffusing member formed in a shape extending from the other side of the light guide plate facing the reflecting plate toward both ends of the opposite side is provided on the light guide plate, and the reflecting mirror member or An illumination device, wherein the light guide plate is divided into three parts corresponding to light sources by a light diffusion member. 2. The reflecting mirror member or the light diffusing member extends from the other side of the light guide plate toward the opposite side,
The illuminating device according to claim 1, wherein the illuminating device is formed into a substantially Y-shaped plane that is branched toward both ends of the opposite side on the way. 3. The reflecting mirror member or the light diffusing member has a cross-sectional shape that is either a flat plate shape, a mountain shape, or a semicircular shape, and the height thereof is formed smaller than the plate thickness of the light guide plate to be embedded. The lighting device according to claim 1, wherein the lighting device is provided.