JPH01183626A - LCD backlight - Google Patents

Abstract

PURPOSE:To obtain the backlight being a thin type and having a high efficiency by providing a light guiding body which is roughly equal to the diameter of a fluorescent lamp tube and consists of transparent plastic, on the same plane along the inside periphery of said fluorescent lamp. CONSTITUTION:As for a liquid crystal use backlight, a fluorescent lamp 1 which is formed so as to come into contact with the surface of the outside periphery of a transparent acryl plate 2 is installed, an aperture part of a shape which has peeled off a phosphor layer is formed in the inside periphery of the fluorescent lamp 1, a milk-white acryl diffusion plate 3 is installed on the acryl plate, and a white lacquer paint on the market is applied to two faces except the upper face in the faces which do not come into contact with the lamp 1 of the acryl plate 2. By preparing a metallic fixture for inserting and holding as one body the lamp 1, the acryl plate 2 and the diffusion plate 3, an integral type backlight can be formed. Also, when the inside surface which faces a lamp phosphor applied part of the metallic fixture is brought to specular working so as to form a structure which does not leak a light beam except the acryl plate 2 from the lamp 1, and 1.5W lamp power is applied, a thin type backlight whose luminous distribution is also uniform is obtained by 40,000cd/m<2> plane luminance on the diffusion plate 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a backlight for a liquid crystal display, and particularly to a backlight for a liquid crystal display that is suitable for providing a backlight with a thin backlight thickness, uniform brightness, and brightness. Concerning light structure.

[Prior Art] As described in Japanese Unexamined Patent Publication No. 102226/1983, a conventional device is a liquid crystal television with a built-in liquid crystal panel or a fluorescent lamp in a U-shape, S-shape, 1M shape, etc. on the back of the panel. Install it and
A reflector plate was placed below the lamp and a diffuser plate was placed above it, and the light was focused on the diffuser plate to be used as a flat light source.

[Problems to be Solved by the Invention] However, the above-mentioned prior art does not take into consideration the thickness of the backlight, and for example, the thickness of the lamp tube and the
nuw, if the thickness of the reflector is 1mm and the thickness of the diffuser is 2+am, then the thickness will be 12+1+2=16im, and if the distance between the lamp and the diffuser is 0, the shape of the lamp will clearly appear on the diffuser. 2-3m for storage
A distance of l11 was required.

Also, as the size of the liquid crystal panel increases, the brightness at the four corners with the diffuser plate becomes extremely low, and only the brightness directly above the lamp increases, making the shape of the lamp even more noticeable, so the tube diameter of the lamp should be increased. Moreover, since it is necessary to take measures such as increasing the distance between the diffuser plate and the lamp, the thickness of the backlight becomes even thicker.

An object of the present invention is to provide a backlight for a liquid crystal display that can be made as thin as possible.

[Means for solving the problem] The above purpose is to arrange the lamp and LCD screen approximately around the
By installing a transparent resin or glass, etc. with good transmittance and a thickness equal to or less than the lamp tube diameter on approximately the same plane, the luminous flux of the lamp is guided into the resin and light is emitted from the upper surface of the resin. This makes it possible to provide a thin and bright backlight.

In addition, if necessary, if a diffuser plate is placed on the resin, the uniformity of the brightness as a flat light source will be increased.In addition, the surface of the resin that does not come into contact with the lamp, except for the top surface, will be reflective. It is necessary to use a reflective paint or a substance with a reflective function, but white paint is the most efficient and can utilize light.

Also, the phosphor is peeled off from part of the surface of the lamp that contacts the resin. By making it a so-called aperture-type fluorescent lamp, the light utilization rate is further increased, and by applying white or silver coating or a shading means to prevent light from emitting from other than the aperture portion, the light utilization rate is further increased. do.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1(a) and (b), transparent acrylic plate 2 (3
, 3' size) is installed so as to be in contact with the three outer periphery surfaces of the fluorescent lamp 1, and the inner periphery of the fluorescent lamp 1 has an aperture portion 5 formed by peeling off the phosphor layer 10 as shown in the figure. A milky-white acrylic diffuser plate 3 is installed on the acrylic plate 2, and two surfaces of the acrylic plate 2 that are not in contact with the lamp 1, excluding the top surface, are coated with a commercially available white lacquer paint.

If the metal fittings for integrally sandwiching the lamp 1 with the acrylic plate 2 and speed-spreading plate 3 are semi-biased, an integrated backlight can be obtained. In addition, the inner surface of the metal fitting facing the lamp phosphor coated part is mirror-finished to create a structure that does not emit light from the lamp 1 to anything other than the acrylic plate 2, and provides a lamp power of 1.5W with a screen size of 3.3 inches. As a result, a thin backlight with a planar luminance of 40,000 c d/rrl' on the diffuser plate 3 and a substantially uniform luminance distribution could be obtained.

Although not used in this example, if a reflective coating of titanium oxide is formed between the phosphor coated part of the lamp 1 and the inner surface of the glass, the efficiency will be approximately 1.8 times that of a case without a reflective coating, and the efficiency will be extremely high. Needless to say, it will get better.

Furthermore, by forming fine-grained alumina or the like in the aperture portion, it is possible to prevent the precipitation of mercury oxide or Na that is formed on the surface of the glass tube when the lamp is turned on, and the quality is further improved.

Further, although the lamp shape and the U-shape are used, it goes without saying that the same effect can be obtained even if the lamp is formed in a shape that surrounds approximately all four sides.

[Effects of the Invention] According to the present invention, it is possible to obtain an extremely thin and highly efficient backlight having a thickness that is almost the same as the diameter of the lamp used as a backlight. , it is possible to obtain a backlight that is easy to implement in a liquid crystal display or the like.

In addition, in terms of cost, the shape of the reflector has been complicated in order to create a uniform surface light source, but a simple acrylic plate can be used, which has the advantage of reducing costs.

[Brief explanation of the drawing]

1(a) and 1(b) are plan and side views of one embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA' in FIG. 1. DESCRIPTION OF SYMBOLS 1... Fluorescent lamp, 2... Acrylic plate, 3... Diffusion plate, 4... White paint, 5... Aperture part, 10
...phosphor layer.

Claims (1)

[Scope of Claims] 1. A fluorescent lamp that includes at least one or more bent portion at approximately right angles, has electrodes at both ends, and is filled with a rare gas and mercury for starting aid, and is on the same plane along the inner periphery. A liquid crystal characterized in that there is a light guide made of transparent plastic on the top having a diameter approximately equal to the lamp tube diameter, and a white or silver reflective film is provided on the bottom surface of the light guide and the surface not in contact with the lamp. Backlight for. 2. The backlight for a liquid crystal display according to item 1, characterized in that a surface of the lamp that is in contact with the plastic has a surface that is not coated with phosphor.