JPH03160489A - Back illuminating device - Google Patents

Abstract

PURPOSE:To efficiently utilize the light generated from a light source by combining a saw tooth-shaped undulated diffusion plate in such a manner that saw tooth-shaped projecting parts are disposed on the center of the light source. CONSTITUTION:This light source is constituted by building the light diffusion plate as the saw tooth-shaped undulated diffusion plate 6 between the cylindrical light source 2 and a front display panel 3 to efficiently irradiate the front display panel 3 with the light form the cylindrical light source 2. For example, the front face display panel 3 is a milky white methacrylic resin plate and the cylindrical light source 2 is a cold cathode ray tube. The saw tooth-shaped undulated diffusion plate 6 is formed by using a transparent acrylic plate having micro-ruggedness on one surface and subjecting the refractive parts to working to curved surfaces. The loss of the light arriving at the front display panel is decreased in this way and the light is efficiently utilized. The back illuminating device which is uniform in luminance distribution is thus obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to various display elements, particularly word processor personal computers, computer terminal devices, or back illumination devices for liquid crystal display panels such as televisions. Eastern technology] Conventionally, round armor a' yt. RIP. The backlighting device used for the fi was of the type shown in Figure 1, t411[1. That is, if the light emitted from the cylindrical light source 2 housed in the lamp house opening is directly irradiated onto the front display panel a, the brightness on the front display panel 3 will be unbalanced (brightness unevenness). As a means of correcting this to some extent,
A halftone screen (lighting curtain) 4 is interposed between the conical light R2 and the regular image display panel 3. However, the dot pattern screen l1 requires a high degree of M at its mounting position, which poses some operational difficulties. In addition, since a method is adopted to reflect the light irradiated onto the front display panel 3, the light generated from the light source is efficiently used.
There are drawbacks such as not being able to use fil. [Means for solving the problem] In order to solve this problem, instead of the conventional screen 4 shown in FIG. The above-mentioned problem was solved by inserting a serrated relief diffusion plate 6 with a curved surface. That is, in FIG. 3, a sawtooth-shaped undulating diffuser plate 6 is installed as a light diffusing plate between the yen-like light R2 and the physical display panel 3, and the light is transmitted from the cylindrical source 2 to the IE screen display panel 2. It is something that can be efficiently and effectively used. [Embodiment of the present invention] An embodiment of the present invention will be explained based on FIG. 3. 3 in the diagram
is the front display panel, which in this case is made of milky white methacrylic wood r1@. 2 is a cylindrical light source, and this 4th one is a cold negative return tube of FLE-8.253 (As) made by Elebum. 5 is a light reflecting plate, in this case, a high-reflection-rate white reflector having an anti-114 rate of 85% or more ($4 FFi
It was used. 6 is a serrated diffusion plate, and in this case, a transparent acrylic plate with minute irregularities on one side was used. The distance between each of the four cylindrical light sources 2 is 29 m +
n. The thickness of the serrated diffuser plate 6 is 1 mm, and the height difference is 6 mm. The distance between the convex parts is 29 mm+ The bending part has a curved surface. In this example, when the cold cathode tube is lit with a power of 3.6 watts per l, it produces n1% brightness of 2500 cd on an iE Wt display panel a having a width of 135 mm + length of 223 mm.
/m2. We obtained the measurement results of the luminance distribution of H low luminance of 2045 cd/m2. In other words, it was confirmed that the brightness distribution difference was within the range of approximately ±10%. [Effects of the Invention] By using the backlighting device according to the present invention, a backlighting H position that reduces the loss of light reaching the front display panel, can be used efficiently, and has a uniform brightness distribution is realized. did it.

[Brief explanation of the drawing]

Figure I is a perspective view of a conventional back WJ illumination device. FIG. 2 is a cross-sectional view showing a screen with a dot pattern of a conventional back ultralight device, 'IP. Figure 3 shows an embodiment of the present invention. This is diagram I. In addition, each symbol in the figures from Figures 1 to 3 indicates the following. l: Lamb House,
2: Cylindrical light source, 3: iE surface display panel, 4: @ dot pattern screen (lighting curtain), 5: light reflecting plate, 6: serrated relief diffuser plate Figure 2

Claims (1)

[Claims] A front display panel is provided on the top surface of a thin, substantially parallelepiped lamp house, a plurality of cylindrical light sources are arranged inside the lamp house, and a plurality of refracting sections are arranged in the space between the front display panel and the light sources. 1. A backlighting device characterized in that a sawtooth-like undulating diffuser plate having a sawtooth shape is combined in such a way that a sawtooth-like protrusion is arranged above the center of a light source.