JPH1082914A - Back light device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back light device suppressing the generation of luminance irregularity and having little luminance irregularity, by alternately arranging high voltage sides and low voltage sides of plural fluorescent tubes. SOLUTION: First to a fourth fluorescent tubes 2a-2d are mounted so that the high voltage sides and the low voltage sides are alternately arranged. When the first to the fourth fluorescent tubes 2a-2d are turned on, on the left side of a back light device 1, high luminance on the high voltage side of the first and the third fluorescent tubes 2a, 2c and low luminance on the low voltage side of the second and the fourth fluorescent tubes 2b, 2d are mutually canceled and, on the right side of the back light device 1, low luminance on the low voltage side of the first and the third fluorescent tubes 2a, 2c and high luminance on the high voltage side of the second and the fourth fluorescent tubes 2b, 2d are mutually canceled. Consequently, luminance on both left and right side parts are averaged and the back light device 1 having almost uniform brightness over a whole surface of a diffuser plate 4 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device used as a backlight of a liquid crystal panel.

[0002]

2. Description of the Related Art As a backlight device used for a liquid crystal panel or the like, those shown in FIGS. 4 and 5 are known. FIG. 4 is a cross-sectional view of a conventional backlight device. The backlight device 101 includes a plurality of fluorescent tubes 102... 102 as light emitters, a diffusion plate (light diffusion plate) 103 disposed on the front side of the fluorescent tubes 102. The reflecting plate 104 made of synthetic resin and the fluorescent tubes 102...
3, a chassis 105 to which the reflection plate 104 is attached and a cover 106 are provided. The fluorescent tubes 102 ... 1
The light reflected by the light source 02 and the reflection plate 104 is diffused by the diffusion plate 103 and applied to a liquid crystal panel (not shown).

As shown in the plan view of FIG. 5, the plurality of fluorescent tubes 102 are arranged in parallel with their high-voltage side and low-voltage side aligned. In FIG. 5, reference numeral 107 denotes an inverter circuit board.

[0004]

The above-mentioned conventional backlight device 101 is arranged in parallel with the high-voltage side and the low-voltage side of the fluorescent tubes 102. Diffuser 1 with high pressure side
The other side 103b of the diffusion plate 103 where the low pressure side of the fluorescent tubes 102 is arranged becomes dark (low brightness), and the one side 103a side of the diffusion plate 103 becomes dark (low brightness). Remarkable luminance unevenness occurred on one side 103a side and the other side 103b side.

The above-mentioned uneven brightness is mainly caused by the occurrence of a leakage current on the low voltage side of the fluorescent tubes 102... 102 as shown by arrows in FIG.

Therefore, by suppressing the occurrence of leakage current on the low voltage side of the fluorescent tubes 102... 102, it is possible to suppress the luminance unevenness. As means for suppressing the generation of the leakage current, it is conceivable to increase the distance between the fluorescent tubes 102... 102 and the adjacent conductors.
1 has a problem that the thickness T becomes large.

An object of the present invention is to provide a backlight device which suppresses the occurrence of uneven brightness and does not cause uneven brightness without taking measures to increase the distance between the fluorescent tube and the adjacent conductor. is there.

[0008]

SUMMARY OF THE INVENTION The present invention provides a backlight device in which a plurality of fluorescent tubes are arranged in parallel, by alternately arranging the high-voltage side and the low-voltage side of the plurality of fluorescent tubes. The high luminance on the side and the low luminance on the low voltage side are mutually canceled between the low luminance on the low voltage side and the high luminance on the high voltage side of the adjacent fluorescent tube, thereby suppressing the occurrence of luminance unevenness.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a backlight device 1 according to the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the backlight device 1. The backlight device 1 includes first to fourth four fluorescent tubes 2a as light emitters.
2d, a reflecting plate 3 for reflecting the light of the fluorescent tubes 2a to 2d, a diffusing plate 4 for diffusing the light from the fluorescent tubes 2a to 2d and the reflecting plate 3 and hitting a liquid crystal panel (not shown). Drive (inverter) of the fluorescent tubes 2a to 2d
A circuit board 5, a chassis 6 for assembling the fluorescent tubes 2 a to 2 d, a reflection plate 3, a diffusion plate 4, and the like, and a cover 7 are provided.

The reflecting plate 3 is formed in a rectangular box shape from a synthetic resin, a sheet metal, or the like, and has a corrugated reflecting surface portion 3a at a center portion, and the reflecting surface portion 3a.
Of the inverter circuit board 5
b, 3b are provided.

As shown in FIG. 2, the reflection surface portion 3a
Has a number of recesses 11... 11 parallel to each other corresponding to the number of the fluorescent tubes 2 a to 2 d.
The fluorescent tubes 2a to 2d are respectively arranged at the center of the light-emitting element 1 as shown by a two-dot chain line.

The bottom surface 11a of the recess 11 is formed as a flat surface parallel to the diffusion plate 4, and both side surfaces 11b and 11c of the recess 11 are formed at an angle of approximately 45 ° with respect to the diffusion plate 4. It is formed on an inclined surface.

A hook-shaped clamp 12 is provided on the bottom surface 11a of the concave portion 11.
11 hold the fluorescent tubes 2a to 2d in the recesses 11...

As shown in FIG. 3, the first to fourth fluorescent tubes 2a to 2d are connected to the high voltage side of the first and third fluorescent tubes 2a and 2c so that the high voltage side and the low voltage side alternate. Are located on the left side of the backlight device 1 in FIG. 3 and the low-voltage side is on the right side, while the low-pressure sides of the second and fourth fluorescent tubes 2b and 2d are on the right side of the backlight device 1 in FIG. It is installed with it located on the left side.

Since the backlight device 1 of the embodiment has the above-described structure, if the first to fourth fluorescent tubes 2a to 2d are turned on, the left-hand side of the backlight device 1 in FIG. The high luminance on the high voltage side of the first and third fluorescent tubes 2a and 2c and the low luminance on the low voltage side of the second and fourth fluorescent tubes 2b and 2d cancel each other, and the right side of the backlight device 1 In the backlight device, the low luminance on the low voltage side of the first and third fluorescent tubes 2a and 2c and the high luminance on the high voltage side of the second and fourth fluorescent tubes 2b and 2d cancel each other. The brightness of the left and right sides of the light-emitting device 1 is averaged, and the backlight device 1 having substantially uniform brightness over the entire surface of the diffusion plate 4 can be obtained. In the embodiment, four fluorescent tubes are used, but the number of fluorescent tubes is four.
Not limited to books, but may be smaller or larger.

[0016]

The backlight device of the present invention has the following effects.

(1) It is possible to prevent a difference in brightness between one side and the other side in the length direction of the fluorescent tube of the backlight device, and to make the backlight device substantially uniform over the entire surface of the diffusion plate. Brightness can be set.

(2) The brightness of the backlight device can be made uniform without suppressing the generation of leakage current in the fluorescent tube. It is not necessary to increase the distance of the backlight device, and the backlight device can be made compact.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view.

FIG. 4 is a sectional view of a conventional example.

FIG. 5 is a plan view of a conventional example.

[Explanation of symbols]

 1. Backlight device, 2a to 2d: Fluorescent tube.

Claims (1)

[Claims] 1. A backlight device in which a plurality of fluorescent tubes are arranged in parallel, wherein the plurality of fluorescent tubes are arranged alternately on a high voltage side and a low voltage side.