JPH08262235A - Illumination device - Google Patents

Abstract

PURPOSE: To provide an illumination device which is effective for preventing the degradation in luminance and uneven luminance by enhancing the function of light control patterns formed on the rear surface of a light transmission plate and allows the effective utilization of light source light. CONSTITUTION: A cylindrical fluorescent lamp 2 is arranged as a light source facing one side end face 11 of the light transmission plate 10 in parallel therewith and the light control patterns are formed on the rear surface 13 of the light transmission plate 10 by providing the rear surface with plural reflection recessed parts 15 in parallel with this fluorescent lamp 2. A reflection layer 20 or reflection sheet 30 is formed or joined over the entire area on the rear surface 13 of the light transmission plate 10 to cover the groove surfaces of these reflection recessed parts 15. The reflection layer 20 or reflection sheet 30 covers the groove surfaces of the reflection recessed parts 15 by biting these parts and, therefore, the generation of hollow parts between the reflection recessed parts 15 and the reflection layer (reflection member) like heretofore does not arise and the repetition of plural times of refraction of the light escaping from the hollow parts and returning again to the light transmission plate 10 does not arise. The degradation in the luminance by the weakened luminous intensity is obviated and the occurrence of 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. FIG. 3 is a side sectional view showing an example of the edge light type illumination device. The device is composed of a light source and a light diffusion member, and for example, a tubular fluorescent lamp 2 is used as the light source. A member forming the light diffusing member includes a light guide plate 1 having a flat rectangular shape made of a transparent acrylic resin plate or the like, and a reflecting plate or a reflecting sheet 3 as shown in the drawing on the back surface 1c side.
And the diffusion plate 4 is arranged on the front surface side. The fluorescent lamp 2 of the light source has an end surface 1a on one side of the light guide plate 1.
It is provided to face. Since the backlight desirably requires a surface light source, the irradiation light of the fluorescent lamp 2 is multiply reflected inside the light guide plate 1 to form a surface light source. The reflection sheet 3 reflects the light source light passing through the light guide plate 1 toward the front surface 1d side so as not to leak and backscatter, that is, the reflected light is a liquid crystal panel (not shown) of the LCD arranged above the drawing. Irradiate from behind to. The diffusion plate 4 uniformly diffuses the reflected light emitted from the light guide plate 1 toward the liquid crystal panel. The fluorescent lamp 2 itself is covered with a reflective film 5 in order to prevent light scattering. Further, in order to uniformly emit the light from the fluorescent lamp 2 from the front surface 1d of the light guide plate 1, a plurality of reflective recesses 6 are provided in parallel with the fluorescent lamp 2 on the back surface 1c of the light guide plate 1 facing the reflection sheet 3. To form a dimming pattern. With this dimming pattern, the light 7a from the fluorescent lamp 2 is applied to the reflection concave portion 6 to be reflected as reflected light 7b and emitted from the surface 1d of the light guide plate 1. This allows
The brightness is made uniform to suppress the occurrence of uneven brightness.

[0003]

By the way, in such a conventional edge-light type illuminating device, a hollow portion 8 is provided between the plurality of reflecting concave portions 6 formed on the back surface 1c of the light guide plate 1 and the reflecting sheet 3. Has become. Therefore, depending on the path in which the light from the fluorescent lamp 2 passes through the inside of the light guide plate 1,
For example, refraction is repeated several times, such as a light ray 9 passing through the hollow portion 8 of the reflection concave portion 6 to be reflected by the reflection sheet 3 and then emitted again as reflected light 9a through the inside of the light guide plate 1. This means that the radiant energy of ray 9
That is, the luminous intensity (candela) is weakened, which causes a decrease in brightness and uneven brightness, and the function of the dimming pattern is halved. Therefore, it is an object of the present invention to provide a lighting device that enhances the function of the dimming pattern formed on the back surface of the light guide plate, is effective in preventing a decrease in brightness and uneven brightness, and can efficiently use the light from the light source.

[0004]

In order to achieve the above-mentioned object, an illuminating device according to the present invention has a light source arranged in parallel with one side of a rectangular flat light guide plate, and a plurality of reflective concave portions arranged in parallel with the light source. A dimming pattern is formed on the back surface of the light guide plate at intervals in the plate width direction between one side and the opposite side, and covers the groove surface of the reflection recess and reflects the entire back surface of the light guide plate. Layers are formed. Further, in the illuminating device of the present invention, the reflective layer is formed by following a dimming pattern by a film forming means of printing, coating, vapor deposition or plating of a reflective material to a predetermined thickness and biting into the reflective concave portion. can do.

[0005]

The dimming pattern formed by the plurality of reflective recesses on the back surface of the light guide plate has the reflective layer formed following this shape, and the reflective layer covers the groove surface of each reflective recess. Since it is formed by biting into the reflective recess, a hollow portion is not formed between the reflective recess and the reflective layer (or the reflective member) unlike the conventional case. Therefore, the light from the cylindrical light source escapes into the hollow portion, is reflected by the reflection layer on the back side, does not repeat refraction several times such as returning to the light guide plate, and avoids a decrease in brightness due to weakening of the luminous intensity. Suppress uneven brightness.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An edge light type backlight device will be described below as an embodiment of the illuminating device according to the present invention with reference to the drawings. Members common or similar to the configuration of FIG. 3 shown as the above-mentioned conventional example are designated by the same reference numerals. Figure 1
The side surface sectional view of the illuminating device of 1st Example is shown. In the rectangular flat light guide plate 10 made of a transparent acrylic resin plate or the like, for example, a tubular fluorescent lamp 2 is arranged as a light source so as to face one side end surface 11 in the plate width B direction in parallel. Further, on the surface 14 side of the light guide plate 10, a diffusion plate 4 having substantially the same rectangular plane area is arranged. Therefore, the natural light from the fluorescent lamp 2 is reflected about once inside the light guide plate 10, is emitted as reflected light from the surface 14, and the internally reflected light emitted from the light guide plate 10 is diffused and uniformized by the diffusion plate 4, The liquid crystal panel (not shown) of the LCD arranged in the upper part of the drawing is configured to illuminate from behind.

In the light guide plate 10 of the first embodiment, the back surface 1
A plurality of reflection concave portions 15 having a circular cross section are provided in parallel to the fluorescent lamp 2 in the plate width B direction at appropriate intervals to form a set dimming pattern. The dimming pattern is formed by appropriately setting the cross-sectional shape and pitch of the reflective recesses 15 so that the light reflected inside the light guide plate 10 is uniformly emitted from the surface 14.

On the other hand, a reflecting layer 20 which is the gist of the present invention is formed following the light control pattern on the back surface 13 side of the light guide plate 10. The reflective layer 20 is formed by a film forming means such as printing, coating, vapor deposition or plating of a reflective material with a predetermined thickness. As the reflective material, it is possible to use a highly-reflective ink that is a white light-concentration mixture of components such as titanium white and barium sulfate, and is used as a solvent to form a film with a predetermined thickness by printing or coating. . In the case of vapor deposition or plating, a metal such as silver or aluminum can be formed in a predetermined dimming pattern by sputtering. The reflective layer 20 formed by such a film forming means also digs into the insides of the plurality of reflective concave portions 15 formed on the back surface 13 of the light guide plate 10 to form a convex biting portion 21. The groove surface of the reflection concave portion 15 on the light guide plate 10 side is completely covered by the biting portion 21.

In the first embodiment, the following effects can be obtained with the above configuration. Light from the fluorescent lamp 2 is guided by the light guide plate 1.
0 becomes parallel light 16 and oblique light 17 and is incident from the front end face 11. The light guide plate 10 is directly included in the parallel light 16.
There is also one that travels toward the other end face 12, but, for example, the oblique light 17 and the internally reflected light hit the at least one reflection concave portion 15 in the dimming pattern and are reflected about once.
The reflected light 17a is emitted from the surface 14 of the light guide plate 10, passes through the diffuser plate 4 and is uniformly diffused, and uniformly illuminates the liquid crystal panel of the LCD from behind. This enables a clear display on the liquid crystal panel.

When the light guide plate 10 is a transparent acrylic resin, the refractive index of the light is 1.495, and the internally reflected light 17a having an incident angle of 41 ° 98 or less is emitted from the surface of the light guide plate 10. be able to. Internally reflected light having a critical angle or more is repeatedly internally reflected by the light guide plate 10, and thus it is difficult to be effective irradiation light to the liquid crystal panel. Therefore, in order to suppress the number of reflections due to internal refraction of light as much as possible, the shape of the reflection recess 15 is appropriately set in the dimming pattern.

When, for example, oblique light 17 of the light emitted from the fluorescent lamp 2 strikes the reflection recess 15, the groove surface of the reflection recess 15 is completely covered with the biting portion 21 of the reflection layer 20 from the outside. Since it has a curved shape, it does not come out of the light guide plate 10 from the reflection concave portion 15, and can be suitably reflected by the biting portion 21 of the reflection layer 20 and emitted from the surface 14 as reflected light 17a. As a result, the light guide plate 10 is subjected to uniform internal reflection over the entire width thereof, so that the brightness can be kept uniform.

Next, FIG. 2 shows a second embodiment according to the present invention. In the second embodiment, a reflection layer formed by following the light control pattern on the back surface 13 of the light guide plate 10 joins the reflection sheet 30. As the reflecting sheet 30, for example, a low-foaming sheet made of white polyethylene terephthalate (PET) or one coated with the same quality can be used. Therefore, the reflection sheet 30 having the predetermined thickness t is prepared, and the reflection sheet 30 is provided on the back surface 1 of the light guide plate 10.
Following the light control pattern of No. 3, they are joined by means such as adhesion and welding. The reflection sheet 30 is joined to the flat surface of the back surface 13 and the reflection recesses 15 so as to cover the plurality of reflection recesses 15 along the groove surfaces to form the biting portion 31.

As described above, in the second embodiment, since the reflection layer is formed by the reflection sheet 30, the light from the cylindrical fluorescent lamp 2 is generated as in the case of the first embodiment.
For example, it becomes oblique light 17 or internally reflected light, hits at least one reflection concave portion 15 in the dimming pattern, is reflected about once, is emitted as reflected light 17a from the surface 14 of the light guide plate 10, passes through the diffusion plate 4, and is evenly distributed. LCD diffused
Irradiate the liquid crystal panel of from the back evenly. This enables a clear display on the liquid crystal panel. Even if the oblique light 17 hits the reflection recess 15, the groove surface is reflected from the outside.
Since it is completely covered and lined with the biting portion 31 of 0, as shown in the first embodiment, it does not escape from the reflection concave portion 15 to the outside of the light guide plate 10, and the light guide plate 10 has a uniform width over the entire width. As a result, the brightness is uniformized.

In the second embodiment, the reflection sheet 30 may be preliminarily formed as a single piece having the same cross-sectional shape as the corrugated dimming pattern including the reflection recess 15 on the light guide plate 10 side. On the other hand, by using a material having flexibility or elasticity as the material of the reflection sheet 30 and pressing, for example, a material which is melted and softened against the light control pattern of the light guide plate 10, a large number of reflection recesses 15 are formed. It can also be formed following the shape of the included light control pattern.

[0015]

As described above, in the illuminating device according to the present invention, the reflecting layer is formed on the back surface of the light guide plate in accordance with the dimming pattern formed by the plurality of reflecting recesses, and the reflecting layer has each reflecting portion. Since it digs into the recess and completely covers the groove surface, the reflective recess and the reflective layer (or the reflective member) as before
There is no hollow part between and, the light from the cylindrical light source escapes into the hollow part, is reflected by the reflective layer on the back side, and does not repeat refraction several times such as returning to the light guide plate. It is possible to avoid the decrease in brightness due to the increase in brightness and suppress the occurrence of uneven brightness. For example, when it is used as an LCD lighting device, it is possible to perform clear and high-quality display.

[Brief description of drawings]

FIG. 1 is a side sectional view of an edge light type backlight device shown as a first embodiment of a lighting device according to the present invention.

FIG. 2 is a side sectional view of an edge light type backlight device shown as a second embodiment of the lighting device.

FIG. 3 is a side sectional view of an edge light type backlight device shown as a conventional example of a lighting device.

[Explanation of symbols]

 2 Cylindrical fluorescent lamp 4 Diffusion plate 10 Light guide plate 13 Back surface of light guide plate 14 Surface of light guide plate 15 Reflective concave portion of dimming pattern 20 Reflective layer 21 Reflective layer biting portion 30 Reflective sheet (reflective layer) 31 Reflective sheet biting portion

Claims (2)

[Claims] 1. A light source is arranged in parallel with one side of a rectangular flat light guide plate, and a plurality of reflective recesses are arranged in parallel with the light source on the back surface of the light guide plate in the plate width direction between one side and its opposite side. In a lighting device having a dimming pattern formed by arranging the light guiding plate, a reflecting layer is formed over the entire back surface of the light guide plate so as to cover the groove surface of the reflection recess. 2. The reflection layer is formed by following a dimming pattern by a film forming means of printing, coating, vapor deposition or plating with a reflection material to a predetermined thickness and biting into the reflection recess. The lighting device according to claim 1, wherein: