JPH0659828U - Backlight device for LCD - Google Patents

Abstract

(57) [Summary] [Object] To provide a backlight device used for a display device of a liquid crystal display device and capable of obtaining uniform illuminance over the entire screen. The backlight device may include a semi-cylindrical recess formed in the light emitting front surface of the light guide plate in a first direction and two side surfaces of the light guide plate that are orthogonal to the first direction. Two lamps, a light diffuser plate provided adjacent to the light emitting front surface, a reflector plate provided adjacent to the lower part of the light emitting back surface, and a reflective film pattern provided between the light guide plate and the reflector plate. To have. As a result, a backlight device having high brightness and uniform brightness can be easily manufactured.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a backlight device for an LCD, and more particularly to a backlight device that can obtain a uniform illuminance over the entire screen used in a display device such as a liquid crystal display device.

[0002]

[Prior art]

 Conventional backlight devices include "Compact LCD luminance" disclosed in U.S. Pat. No. 4,974,122 and "Backlighting device for a liquid crystal panel" disclosed in U.S. Pat. No. 4,937,709. . The backlight device disclosed in U.S. Pat. No. 4,937,709 reduces the size of the reflective film pattern in the central portion of the panel in order to solve the uneven brightness which occurs locally, and reduces the size of the panel edge. The size of the reflection film pattern is increased in the portion. The backlight device for an LCD disclosed in U.S. Pat. No. 4,974,122 has a light guide plate in which a portion adjacent to the lamp has a thickness larger than that of the center of the body.

1 and 2 schematically show a conventional backlight device for a liquid crystal display device.

Referring to FIG. 1, a conventional backlight device has a light diffusion plate 1, a light guide plate 3 attached to the bottom of the light diffusion plate 1, and two column type light guide plates provided in the vicinity of opposite ends of the light guide plate. The lamp 2 includes a reflection plate 4 provided below the light guide plate and a reflection film pattern 5 formed between the light guide plate and the reflection plate. The light guide plate 3 receives light from lamps located at both ends of the light guide plate 3 and guides the light into the light guide plate, so that the light advances in the light guide plate while part of the light is emitted through the light diffuser plate. Further, the reflection plate 4 is for reflecting, among the lights incident on the light guide plate 3, the scattered light to the light diffusion plate 1. In particular, a reflecting film pattern 5 for reflecting the light while diffusing it toward the light diverging plate is formed on the reflecting plate 4. At this time, as shown in FIG. 2, the reflective film pattern 5 is formed so that the reflective film pattern 5 has different sizes symmetrically with respect to the vertical and horizontal directions with respect to the inner central portion of the light guide plate 3. . That is, the reflection film pattern 5 is formed so as to be larger toward the portion where the lamp 2 is not provided above and below in the center of the light guide plate 3, and on the other hand, at the inner center of the light guide plate 3, the reflection film pattern is gradually increased toward the edge. 5 was formed small. This is because the intensity of the light transmitted from the lamp 2 varies depending on the distance, so that in the portion where the light intensity is the least, that is, the portion farthest from the lamp, the reflective film pattern 5 is printed with the largest size and a large amount. Light emission is increased by light reflection, and the size of the reflection film pattern 5 is reduced in the part where the light intensity is the strongest, that is, the part close to the lamp 2 to reduce the amount of reflection of this light. This is because the brightness of the entire liquid crystal display panel is made uniform by lowering the brightness.

However, in the conventional surface light source device as described above, the size of the reflective film pattern is symmetrical with respect to the direction aligned with or orthogonal to the pillar-shaped lamp with the center of the light guide plate 3 as the center. Differently printing requires very high printing accuracy, which makes the work difficult.

Further, when the length of the liquid crystal display element increases in the longitudinal direction of the lamp, or in the vertical direction in FIG. 2, the brightness of the entire panel becomes uneven unless the reflection film patterns are symmetrical. Therefore, there is a problem that the size of the reflective film pattern must be changed.

[0007]

[Problems to be solved by the device]

 An object of the present invention is to provide a backlight device that emits light of high brightness and uniform brightness and is easy to manufacture in order to solve the problems of the conventional backlight device described above. is there.

[0008]

[Means for achieving the object]

 In order to achieve the above object, the present invention provides a backlight device for an LCD including a light guide plate having a light emitting front surface and a light emitting back surface at predetermined intervals, in a first direction on the light emitting front surface of the light guide plate. A semi-cylindrical recess formed, two lamps provided adjacent to both side surfaces of the light guide plate orthogonal to the first direction, and a light diffuser plate provided adjacent to the light emitting front surface, A backlight device for an LCD, comprising: a reflection plate adjacent to the lower side of the light emission back surface; and a reflection film pattern provided between the light guide plate and the reflection plate.

[0009]

[Action]

 With the backlight device according to the present invention, it is possible to obtain a high-intensity light beam with almost no difference in brightness over the entire surface of the light guide plate.

Further, the size of the reflection film pattern formed between the light guide plate and the reflection plate is differently coated only in the direction orthogonal to the two pillar-shaped lamps, and in the direction parallel to the pillar-shaped lamps. By forming the reflective film pattern with the same size, a high brightness backlight device can be manufactured in a simpler manner.

[0011]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a schematic perspective view showing a backlight device according to the present invention, and FIG. 4 is a sectional view taken along line AA ′ of FIG. 5 is a view showing a print pattern of the reflective film of the backlight device of FIG.

3 and 4, the backlight device according to the present invention includes a light guide plate 30 having a semi-cylindrical recess and a predetermined thickness, and a light guide plate orthogonal to the AA 'direction. Two lamps 20 provided adjacent to the side surfaces, a light diverging plate 10 attached and provided on the light guide plate, a reflection plate 40 provided below the light guide plate, and a reflection provided between the light guide plate and the reflection plate. The film pattern 50 is provided. The plurality of reflection film patterns 50 are formed between the light guide plate 30 and the reflection plate 40 at a predetermined interval in order to diffusely reflect the light incident on the light guide plate 30. At this time, the reflective film pattern 50 is preferably formed with a uniform width.

On the other hand, the light guide plate 30 provided on the lower surface of the light diverging plate 10 for guiding the light from the lamp 20 to the light diverging plate 10 has the above-mentioned lamp from the central axis between both ends where the lamp is not provided. Is gradually thickened while approaching both end portions where no is provided. At this time, it is preferable that the thickness of both end portions of the light guide plate 30 where the lamp 20 is not provided is about 5 to 20% thicker than the thickness of the central portion. The light guide plate 30 is preferably manufactured by injection molding or hot rolling.

In the backlight device according to the present invention constructed as described above, when light is emitted from the lamp 20, the light is guided to the light guide plate 30. Most of the light guided to the light guide plate 30 is reflected by the light diverging plate 10 by the reflection film pattern 50 formed between the reflection plate 40 and the light guide plate 30.

According to an embodiment of the present invention, the reflective film pattern is formed to be largest in a central portion between both ends of the lamp to increase light reflection. Further, the light guide plate 30 is formed to be gradually thicker as it approaches the both ends from the central axis portion between the both ends where the lamp is not formed, and reflects a large amount of light from the both ends.

Accordingly, the size of the reflective film pattern 50 formed between the light guide plate 30 and the reflective plate 40 in order to solve the non-uniformity of the brightness in the conventional surface light source device is two pillars. A simple method for a high-brightness backlight device by coating differently only in the direction orthogonal to the lamp and forming a reflective film pattern of the same size in the direction parallel to the pillar-shaped lamp. Can be manufactured in.

[0018]

[Effect of device]

 As described above, according to the backlight device of the present invention, there is no difference in brightness that occurs partially, and it is not necessary to form a reflective film pattern having a different size to solve the conventional brightness imbalance. It is possible to manufacture a simpler backlight device.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional backlight device.

FIG. 2 is a plan view schematically showing a reflection film pattern formed on a reflection plate of a conventional backlight device.

FIG. 3 is a schematic perspective view of a backlight device according to the present invention, in which both ends without a lamp are thicker than the central part.

4 is a cross-sectional view taken along the line AA ′ of the backlight device of FIG.

5 is a plan view schematically showing a reflection film pattern formed on a reflection plate of the backlight device of FIG.

[Explanation of symbols]

10 ... Light diffuser plate, 20 ... Lamp, 30 ... Light guide plate, 40 ...
Reflector, 50 ... Reflective film pattern.

Claims (3)

[Scope of utility model registration request] 1. A backlight device for an LCD, comprising a light guide plate having a light emitting front surface and a light emitting back surface at predetermined intervals, wherein a semi-cylindrical shape is formed on the light emitting front surface of the light guide plate in a first direction. A concave portion, two lamps provided adjacent to both side surfaces of the light guide plate orthogonal to the first direction, a light diverging plate provided adjacently on the light emitting front surface, and a light emitting back surface of the light emitting back surface. A backlight device for an LCD, comprising: a reflection plate provided adjacently below and a reflection film pattern provided between the light guide plate and the reflection plate. 2. The reflective film patterns are formed in different sizes in parallel to the first direction while maintaining a predetermined distance, and are formed in the same size in a direction orthogonal to the first direction. The backlight device according to claim 1, wherein: 3. The backlight device according to claim 1, wherein the semi-cylindrical recess is formed so as to become gradually deeper as it approaches the central axis from both ends where the lamp is not provided.