JP2001006415A - Backlight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight having an easy-to-handle reflection control sheet and a small amount of defective products. SOLUTION: In this edge light backlight, a light source 3 is disposed opposite to a side face 2a of a light guide plate 2, while the rear face 2b of the light guide plate 2 is attached with a reflection control sheet 4. The sheet 4 comprises a light scattering film 5 formed by applying embossing 5a to a transparent film, and a light reflecting film 6 attached on the film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge light type backlight in which a light source is arranged on the side of a light guide plate.

[0002]

2. Description of the Related Art Conventionally, a light guide plate used for an edge-light type backlight has a white dot pattern for reflection formed by printing on the back surface thereof (for example, Japanese Patent Application Laid-Open No. 6-273759).

[0003]

As described above, the method of forming a pattern for reflection by printing involves a large number of manufacturing steps and prints on a rigid light guide plate, so that its handling is not easy. . In particular, when a printing failure occurs, it is not easy to regenerate it. Therefore, an object of the present invention is to provide a backlight which is easy to handle and has a low incidence of defective products.

[0004]

A backlight according to the present invention is an edge-light type backlight in which a light source is arranged on a side surface of a light guide plate, wherein a reflection control sheet is attached to a back surface of the light guide plate. And a light-transmitting film formed by embossing a light-transmitting film and a light-reflecting film attached to the film.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the backlight according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, this backlight 1 uses an acrylic plate having good light transmission as a light guide plate 2 and a light source 3 such as a cold-cathode tube is disposed on a side surface 2a of the backlight 1. It is configured as a light. Although the light guide plate 2 has a wedge-shaped cross section, other shapes can be used. A reflection control sheet 4 is closely mounted on the bottom surface 2b of the light guide plate 2.

As shown in FIG. 1, the reflection control sheet 4 is a flexible sheet having a light diffusing film 5 and a light reflecting film 6 attached thereto. The light-diffusing film 5 is made of a transparent film such as acrylic or polyethylene phthalate, and is formed by embossing by forming a plurality of embossed (indented) portions 5a in one surface on one surface. .
The depth (d), the curvature (r) in the depth direction, and the diameter (l) of each emboss 5a are unified to predetermined preset values. The reflection film 6 is made of a resin film such as an acrylic resin or a polyethylene phthalate having a mirror surface formed on the surface by a white system or a metal deposition or the like, and reflects the light to be emitted to the back side of the light scattering film 5. In addition, it is attached to the light-diffusing film 5.

The light-diffusing sheet 4 provided with the embossed portions 5a having a uniform shape has a distribution of the embossed portions 5a, that is, a two-dimensional arrangement of the embossed portions 5a, so that the brightness on the surface 2c of the light guide plate 2 becomes uniform. Has been optimized. Here, optimization of the arrangement of the embossments 5a is performed by fixing parameters such as the depth (d), the curvature (r) in the depth direction, and the diameter (l) of each embossment 5a, and then setting the embossment 5a in the next stage, for example. This can be performed relatively easily by executing a simulation using the distances in the X and Y directions and the like as parameters. The reflection control sheet 4 thus optically designed is attached to the back surface 2b of the light guide plate 2 in close contact with no air layer.

The backlight 1 having the above structure functions as a surface light source for illuminating the rear surface of a transmission type liquid crystal display device or the like over a wide area. That is, when the light source 3 is turned on, the light enters the light guide plate 2 from the side surface 2a. Part of the light incident on the light guide plate 2 reaches the bottom surface portion of the light guide plate, and most of the light is reflected in the direction of the upper surface 2c of the light guide plate. Here, the reflection control sheet 4 attached to the bottom surface 2 b of the light guide plate 2 is
Functions as a primary reflection surface, and the reflection film 6 functions as a secondary reflection surface. In the light-scattering film 5, the peripheral surface of the emboss formed on the film functions as a reflection surface. Although the emboss 5a reflects light in random directions, its shape and arrangement pattern are set in advance so that light emitted from the light guide plate 2 is uniform. The light reflected by the reflection control sheet 4 and returned to the light guide plate 2 again,
The light exits from the upper surface 2c of the light guide plate 2.

As described above, the reflection control sheet 4 is connected to the light guide plate 2.
It is not necessary to form a dot pattern for reflection on the bottom surface of the light guide plate by printing as in the related art, and the light guide plate can be easily handled at the time of manufacturing, and the manufacturing efficiency can be increased. . In particular, the reflection control sheet 4
Is composed of a flexible sheet to which the transparent film 5 with the embossed formed and the reflective film 6 are attached, so that it is easy to manufacture and easy to handle, and suppresses the occurrence of defects due to backlight manufacturing errors. can do.

In the above-described embodiment, an example in which the shape of the emboss is hemispherical is shown. However, the present invention is not limited to this. For example, as shown in FIGS. Other shapes such as a semi-elliptical spherical shape, a quadrangular pyramid shape, and a triangular pyramid shape can be adopted as the shape of the emboss. Further, as shown in FIG. 4D, the internal space of the embossment 5a may be filled with a resin 5b having a different refractive index from the film instead of the air layer.

[0011]

As described above, according to the present invention, since a reflection control sheet which is easy to handle is used, it is an object of the present invention to provide a backlight having a low occurrence rate of defective products.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of an emboss arrangement pattern of the embodiment.

FIGS. 3A to 3D are cross-sectional views showing examples of embossed shapes of a light-diffusing film.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 back light 2 light guide plate 3 light source 4 reflection control sheet 5 light diffusing film 5 a emboss 6 reflection film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor ▲ Yori ▼ Yasuki 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (72) Inventor Kenichi Narita 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (72) Inventor Takashi Taniguchi 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. FF03 FF06 FF08 GG24

Claims (1)

[Claims] 1. An edge-light type backlight in which a light source is arranged on a side surface of a light guide plate, wherein a back surface of the light guide plate is
A backlight comprising a reflection control sheet attached thereto, the sheet comprising a light-scattering film obtained by embossing a light-transmitting film, and a light reflection film attached to the film.