JPH05303095A - Back light - Google Patents

Abstract

PURPOSE:To increase brightness and to decrease a brightness difference so as to eliminate uneven brightness by halving the distance from the fluorescence discharge tube of the back light formed in such a manner that the light radiated from the fluorescence discharge tube to light transmission bodies is reflected by a reflection sheet and is released from a light diffusion and transmission sheet. CONSTITUTION:This back light is so constituted to be provided with the fluorescence discharge tube 1 which outputs the light, the planar first and second light transmission bodies 2, 3 which are disposed on both sides of the fluorescence discharge tube 1 as a center, the reflection sheet 4 which is extended on one surface disposed with the fluorescence discharge tube 1 and the first and second light transmission bodies 2, 3 and reflects the light radiated from the fluorescence discharge tube 1 to the first and second light transmission bodies 2, 3 and the light diffusion and transmission plate 5 which is extended to face the reflection sheet 4 and releases the reflected light reflected by the reflection sheet 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight formed so that light emitted from a fluorescent discharge tube to a light guide is reflected by a reflection sheet and emitted from a light diffusion / transmission plate.

When a display panel is composed of a transmissive liquid crystal display element, a backlight is provided on the back side of the transmissive liquid crystal display element, and a predetermined image is displayed by the brightness of light emitted from the backlight.

In such a backlight, it is important that the thickness is formed as thin as possible so that the display panel can be formed in a small size, and that the brightness quality is good so that the brightness due to the irradiation light is uniform. ..

[0004]

2. Description of the Related Art Conventionally, the structure is shown in FIG. 5A is a perspective view, and FIG. 5B is a relationship graph of length and brightness.

As shown in FIG. 5A, a side end surface of a plate-shaped light guide body 10 made of a transparent synthetic resin material having a reflection sheet 4 on one surface and a light diffusion / transmission plate 5 on the other surface is superposed. It was formed by providing the fluorescent discharge tube 1 covered with the reflection cover 12 in the above.

Further, an opaque reflection pattern 11 is formed on the side of the light guide 10 to which the reflection sheet 4 is adhered by printing, and the size of the reflection pattern 11 is the fluorescent discharge tube 1
Is set according to the distance from the fluorescent discharge tube 1 such that it is small at a location where the distance from is short, and becomes large as the distance increases.

Therefore, the light PA output by the lighting of the fluorescent discharge tube 1 passes through the light guide 10, and is reflected by the reflection sheet 4 to emit light of which the brightness is P from the emission surface 5A of the light diffusion transmission plate 5. Release is done.

Therefore, by disposing a transmissive liquid crystal display element on the emission surface 5A of the light diffusion / transmission plate 5, an image is displayed by the light of the brightness P. In this case, the light PA passing through the light guide body 10 has a length L of the light guide body 10 as shown in FIG.
Is longer, the light attenuates as the distance from the fluorescent discharge tube 1 increases, and by reflecting the light as it is with the reflection sheet, the brightness becomes P2 near the fluorescent discharge tube 1 as shown by the dotted curve, and the fluorescent light becomes Distance L from discharge tube 1
In the area of, the brightness becomes P1 and it decreases extremely.

Therefore, in practice, the reflection pattern 11 increases or decreases the reflected light in accordance with the distance from the fluorescent discharge tube 1 to reduce the reflected light in the vicinity of the fluorescent discharge tube 1 as shown by the solid line. , The reflected light is increased as the distance of the fluorescent discharge tube 1 increases, and in the vicinity of the fluorescent discharge tube 1, the brightness is set to P12, which is lower than the above-mentioned brightness P2, and is separated from the fluorescent discharge tube 1. At the distance L, the brightness is set to P11 which is higher than the brightness P1 described above, and the fluorescent discharge tube 1
It was taken into consideration that there was a large difference in brightness between the vicinity of and and the distant place, and uneven brightness did not occur.

[0010]

However, in order to increase or decrease the reflected light of the light PA passing through the light guide 10 by the reflection pattern 11, the length of the light guide 10 shown in FIG. When L becomes large, there is a limit to the increase in reflected light, and naturally the brightness P emitted from the emission surface 5A of the light diffusion / transmission plate 5 at a location away from the fluorescent discharge tube 1 becomes small.

Therefore, since the length L of the light guide 10 is increased, there is a difference in luminance between the vicinity of the fluorescent discharge tube 1 and a distant portion, and there is a problem that the quality is deteriorated due to the uneven luminance. ..

Therefore, it is an object of the present invention to reduce the distance from the fluorescent discharge tube by half to increase the brightness and to reduce the uneven brightness by reducing the difference in brightness.

[0013]

FIG. 1 is a diagram illustrating the principle of the first invention, and FIG. 2 is a diagram illustrating the principle of the second invention.

As shown in FIG. 1, a fluorescent discharge tube 1 for outputting light, and plate-shaped first and second light guides 2, 3 arranged on both sides of the fluorescent discharge tube 1 as a center are provided. , The fluorescent discharge tube 1, and the first and second light guides 2 and 3 are stretched over one surface, and the fluorescent discharge tube 1 extends from the first and second light guides 2. , 3
A reflection sheet 4 for reflecting the light radiated to the sheet, and a light diffusion / transmission plate 5 stretched by facing the reflection sheet 4 and emitting the reflected light from the reflection sheet 4. Also, as shown in FIG. 2, a fluorescent discharge tube that outputs light.
1, the plate-shaped first and second light guides 2 and 3 disposed on both sides of the fluorescent discharge tube 1 as a center, the fluorescent discharge tube 1, and the first and second conductors. A reflection sheet 4 which is stretched over one surface on which the light bodies 2 and 3 are arranged and which reflects the light emitted from the fluorescent discharge tube 1 to the first and second light guide bodies 2 and 3, A brightness compensation sheet 6 having a light-shielding pattern 7 which is stretched by facing the reflection sheet and which controls the amount of the reflection light by shielding the reflection light from the reflection sheet, and the brightness compensation sheet 6
A light diffusing and transmitting plate 5 which is superposed on and emits the reflected light.
And so on.

The above-mentioned problems can be solved by such a configuration.

[0016]

Function: That is, in the first invention, the light diffusion / transmission plate 5 is provided on one surface
, And a reflection sheet 4 on the other side,
The fluorescent discharge tube 1 is arranged in the center between the reflection sheet 4 and the reflection sheet 4, and the plate-shaped first and second light guides 2 are provided on both sides of the fluorescent discharge tube 1.
3 are arranged respectively, and the light from the fluorescent discharge tube 1
The reflected light that is output to the light guides 2 and 3 and reflected by the reflection sheet 4 is emitted from the light diffusion transmission plate 5.

Therefore, the distance from the fluorescent discharge tube 1 is halved as compared with the case where the fluorescent discharge tube 1 is provided on the side end surface of the conventional light guide body 10, and the light emitted from the light diffusion / transmission plate 5 is reduced. The brightness can be increased.

Further, in the first invention, the light diffusion / transmission plate 5 and the brightness compensation sheet 6 are provided on one surface, and the reflection sheet 4 is provided on the other surface, and the space between the light diffusion transmission plate 5 and the reflection sheet 4 is provided. The fluorescent discharge tube 1 is arranged in the center of the fluorescent discharge tube 1, and the plate-shaped first and second light guides 2 and 3 are arranged on both sides of the fluorescent discharge tube 1, respectively. Output to the second light guide 2,3,
The reflected light reflected by the reflection sheet 4 is emitted from the light diffusion / transmission plate 5 via the brightness compensation sheet 6.

Therefore, the distance from the fluorescent discharge tube 1 is halved as compared to the case where the fluorescent discharge tube 1 is arranged on the side end surface of the conventional light guide body 10, and the light emitted from the light diffusion / transmission plate 5 is reduced. In addition to increasing the brightness, the light-shielding pattern 7 formed on the brightness compensation sheet 6 shields the reflected light from the fluorescent discharge tube.
It is possible to prevent the occurrence of brightness unevenness by adjusting the brightness in the light diffusing and transmitting plate 5 directly above where 1 is provided, and to improve the brightness quality.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS. FIG. 3 is an explanatory view of an embodiment according to the first invention, (a) is a side sectional view, (b) is a partial view of the first and second light guides, and (c) is length and brightness. Relationship graph, (d1) (d2) (d3) is a side sectional view of a main part, FIG. 4 is an explanatory view of an embodiment according to the second invention, (a) is a side sectional view, and (b) is a luminance. It is a partial view of a compensation sheet. Throughout the drawings, the same reference numerals denote the same objects.

As shown in FIG. 3 (a), plate-shaped first and second light guides 2 and 3 made of a transparent synthetic resin material are arranged on both sides of the fluorescent discharge tube 1 to form one surface. A reflection sheet 4 is stretched on the other side, and a light diffusion / transmission plate 5 is stretched on the other side, and the light PA output from the fluorescent discharge tube 1 is sent to each of the first and second light guides 2 and 3. , A light diffusion and transmission plate that is reflected by the reflection sheet 4
The light P is emitted from the emission surface 5A of 5.

Further, on the surfaces of the first and second light guides 2 and 3 closely attached to the reflection sheet 4, as shown in FIG. 3B,
Reflection patterns 2A and 3A for adjusting the amount of reflected light are formed by printing, etc., and the size of the reflection patterns 2A and 3A is small in the central portion where the fluorescent discharge tube 1 is arranged, and is smaller than the place where the fluorescent discharge tube 1 is arranged. It is formed so that it becomes larger on the side of the end face that is farther away, and the amount of reflected light is increased as it goes farther from the place where the fluorescent discharge tube 1 is installed, so that the brightness at the light diffusion and transmission plate 5 becomes uniform. is there.

Therefore, as described above, the fluorescent discharge tube is provided at the center.
1 is arranged, and the first and second light guides are provided on both sides of the fluorescent discharge tube 1.
When the size of length L is formed by arranging 2,3, as shown by the solid line in (c) of FIG.
P14 becomes higher, and the brightness becomes lower toward the end face side.
Becomes

However, the brightness as in this case is P14 to P13.
By decreasing the value to
The brightness is higher than that of P11, and the brightness is reduced to about 1/2, and uneven brightness due to the decrease in brightness can be eliminated.

Further, in the case of FIG. 4 (a), a light diffusion transmission plate
Luminance compensation sheet 6 made of transparent synthetic resin material on the underside of 5
The light is diffused and transmitted through the brightness compensation sheet 6.
The configuration is the same as above, except for the above.

As shown in FIG. 4B, the brightness compensation sheet 6 is provided with a light shielding pattern 7 formed of a metal layer by vapor deposition or the like, and the size of the light shielding pattern 7 is the fluorescent discharge tube 1.
It is formed so that it is large at the position of the width B just above where B is arranged, and the size becomes smaller as the distance from the width B increases.

Therefore, the light PB emitted from the light diffusing and transmitting plate 5 directly above the fluorescent discharge tube 1 is shielded by the light shielding pattern 7, and the amount of light is adjusted by the size of the light shielding pattern 7. Is.

Therefore, such a brightness compensation sheet 6
As shown in (c) of Fig. 3, the brightness becomes extremely high at P14 at the center of L / 2, as shown by the dotted line C due to the light shielding pattern 7. The brightness can be made smooth, and the brightness is in the range of P14 to P13, and the uneven brightness can be eliminated more than the above.

Further, if the luminance is increased and the luminance is made uniform, the larger the length L is,
The effect will be greater. Furthermore, as shown in (d1) (d2) (d3) of FIG. 3, the first and second light guides 2 and 3 are thicker in the vicinity of the fluorescent discharge tube 1 and become closer to the tip. Tapered,
It may be formed in a curved shape or a stepped shape so as to have a smaller thickness, but the same effect can be obtained even if the thickness is made thinner toward the tip.

[0030]

As described above, according to the present invention,
By disposing the first and second light guides on both sides of the central fluorescent discharge tube, the difference in brightness is reduced even if the emission surface of the light diffusion / transmission plate becomes long. Can be done.

Therefore, as compared with the case where the fluorescent discharge tube is provided on the side end surface of the conventional light guide, the reduction of the luminance is halved, the luminance unevenness can be prevented, and the luminance quality can be improved. , The practical effect is great.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the first invention.

FIG. 2 is an explanatory view of the principle of the second invention.

FIG. 3 is an explanatory diagram of an embodiment according to the first field invention.

FIG. 4 is an explanatory diagram of an embodiment according to the second invention.

FIG. 5 is a conventional explanatory diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluorescent discharge tube 2 1st light guide 3 2nd light guide 4 Reflective sheet 5 Light diffusion and transmission plate

Claims (2)

[Claims] 1. A fluorescent discharge tube (1) for outputting light, and plate-shaped first and second light guides (2, 3) arranged on both sides of the fluorescent discharge tube (1) as a center. And the fluorescent discharge tube (1) and the first and second light guides (2, 3) are stretched over one surface, and the fluorescent discharge tube (1) is connected to the first Second light guide (2,3)
A reflection sheet (4) that reflects the light radiated to the sheet, and the sheet is stretched by facing the reflection sheet (4).
A backlight comprising a light diffusing and transmitting plate (5) for emitting reflected light from (4). 2. A fluorescent discharge tube (1) for outputting light, and plate-shaped first and second light guides (2, 3) arranged on both sides of the fluorescent discharge tube (1) as a center. And the fluorescent discharge tube (1) and the first and second light guides (2, 3) are stretched over one surface, and the fluorescent discharge tube (1) is connected to the first Second light guide (2,3)
A reflection sheet (4) for reflecting the light radiated to the sheet, and a light-shielding pattern which is stretched by facing the reflection sheet and which controls the amount of the reflection light by shielding the reflection light from the reflection sheet. A backlight comprising: a brightness compensation sheet (6) having (7); and a light diffusion transmission plate (5) which is superposed on the brightness compensation sheet (6) and emits the reflected light. ..