JPH04133226U - liquid crystal display element - Google Patents

Abstract

(57) [Summary] [Purpose] Eliminate the illuminance distribution of the liquid crystal panel. [Structure] The luminance distribution of the backlight light source is controlled so that the illuminance distribution of the liquid crystal panel is uniform. Specifically, the concentration of the fluorescent paint in the cold cathode tube of the backlight light source is made higher at both ends of the tube and lower at the center to increase the brightness at both ends. Alternatively, cover the cold cathode tube with a mask with slits, with the slits wide at both ends and narrowed in the center. Furthermore, a layer of white paint is provided between the light source and the reflective plate, and the paint concentration is made higher at a position corresponding to the center of the panel and lower at a position corresponding to the periphery.

Description

[Detailed explanation of the idea]

0001

[Field of application of idea]

This invention relates to a liquid crystal display element with a thin lighting device.

0002

[Prior art]

FIG. 7 shows an example of a liquid crystal display element equipped with a thin lighting device. In the figure, 2 is a liquid A crystal panel, for example, a color liquid crystal panel with a color filter. 4 is a thin light The main body of the brightness device is a pair of light source tubes 6, for example cold cathode tubes or hot cathode tubes. 8 is light A reflector behind the source tube, 10 a reflector inside the main body, 12 a light guide plate made of acrylic resin, etc. It is. , if the longitudinal direction of the light source tube 6 is the x axis and the direction between the light source tubes 6 and 6 is the y axis, then , this thin lighting device has an illuminance distribution, which deteriorates the display quality of the liquid crystal panel 2. . Figure 8 shows the measured values of the illuminance distribution when the illuminance at the center of the liquid crystal panel 2 is set to 1. . As shown in the figure, the illuminance at the center of panel 2 is high, and the illuminance at the periphery is low, especially from the light source. The illuminance near both ends of the tube 6 is low.

0003 JP-A-2-39,123 and JP-A-2-39,124 disclose that a light guide plate 12 has a large number of reflective layers. We aim to solve this problem by setting the area and density of the reflective layer to be higher in the center and lower in the periphery. ing. On the other hand, the inventor used a different method to improve the illuminance distribution of the liquid crystal panel. We considered solving the problem.

0004

[Problems to be devised]

The problem with this idea was to solve the problem of illuminance distribution on the LCD panel on the light source side of the thin lighting device. The task is to solve the problem.

[0005]

[Structure of the idea]

The liquid crystal display element of this invention has a light source tube on one main surface of the liquid crystal panel and a light source tube on the end surface. A liquid crystal display element provided with a thin illumination device, in which a thin illumination device main body is disposed on the main surface side. In the thin lighting device, the amount of light incident on the main body of the thin lighting device from the light source tube is reduced. The cloth is characterized by being high at both ends and low at the center.

[0006]

[Effect of invention]

This idea controls the amount of light incident on the thin lighting device from the light source tube, and The illuminance should be low at both ends of the light source tube, and high at both ends of the light source tube so that the illuminance on the LCD panel is uniform on the light source tube side. so that

[0007]

【Example】

FIG. 1 shows a light source tube 16 with high brightness at both ends and low brightness at the center. to light source tube 16 coats the inner surface with fluorescent paint and extracts the ultraviolet rays generated by the discharge as fluorescence. . For example, three colors of fluorescent paint, red, green, and blue, are used to paint the color liquid crystal panel 2. It matches the spectral characteristics of the color filter and extracts light of the desired color tone. In the example, a ZnCdS/Ag-based paint was used as the red paint, and ZnS was used as the green paint. /Au, Al-based paint and ZnS/Ag-based paint were used as the blue paint. In addition The type of phototube 16 may be a cold cathode type or a hot cathode type. This example uses a light source as a light source. The structure is the same as the conventional example shown in FIG. 7 except that the tube 16 is used, and a thin A side lighting device main body 4 is provided to reflect light from a pair of light source tubes 16, 16 provided on the end surface side. The light is reflected by the projection plate 10 and guided to the liquid crystal panel 4 via the light guide plate 12. Note that there is no light on the end surface side. A source tube is provided, and light is incident on the thin illumination device main body 4 arranged on one main surface side of the liquid crystal panel 2. The point that the liquid crystal panel is illuminated in this manner is the same in other embodiments as well.

[0008] The concentration of the applied fluorescent paint is low at the center and high at both ends, as shown in the center of Figure 1. make it happen. The distribution of the fluorescent paint concentration is the same as that of the liquid crystal panel 2 shown in FIG. Select so that the illuminance distribution is uniform. In this way, the center of low concentration of fluorescent paint The brightness at both ends decreases, and the brightness at both ends increases. As a result, the length of the light source tube 16 is The illuminance distribution along the hand direction (x-axis direction) can be eliminated. In contrast, fluorescent paint concentration In the conventional example in which the LCD panel 2 is kept constant, the illumination at both ends of the liquid crystal panel 2 is degree decreases. When manufacturing the light source tube 16, the fluorescent paint is applied to the inner surface of the tube. It is extremely easy to do, and all you have to do is adjust the concentration so that the concentration distribution of the fluorescent paint occurs. be. Further, in this embodiment, unlike the case where a reflective layer is provided on the light guide plate 12, the reflective layer is There is no loss of light due to reflection of light at The brightness can be kept almost the same as when no paint concentration distribution is provided. More fireflies The distribution of optical paint concentration can be changed continuously and smoothly, so it depends on the presence or absence of a reflective layer. There is no occurrence of stripes.

[0009] FIG. 2 shows a second embodiment. The light source tube 6 in this embodiment has a uniform concentration of fluorescent paint. The illumination distribution on the liquid crystal panel 2 is made uniform by the slits 22. In the diagram 20 is a mask with a semicircular cross section, and the inner surface has a metallic luster or is white. Used as a reflective plate coated with paint. 22 is a slit that narrows the center and closes the periphery. to increase the illuminance around the liquid crystal panel 2. 24 determines the direction of the slit 22 This is a positioning mark for If the light is focused to the center with the slit 22, x in Figure 8 The illuminance distribution in the axial direction can be eliminated. The number of slits 22 does not have to be one, but many. It may be provided. By providing a large number of particularly fine slits, the density and size of the slits can be controlled. By changing both the longitudinal direction and the circumferential direction of the light source tube 6, the liquid crystal panel 2 can be changed. The illuminance distribution can be made uniform. Such an example is shown in FIG. In the figure, 26 is a square 28 is a slit, and the front center position corresponding to the center of the liquid crystal panel 2 is a slit. The product is small, and the area increases toward the periphery in both the longitudinal and circumferential directions. child As a result, the illuminance distribution shown in FIG. 8 can be resolved both in the x-axis direction and in the y-axis direction.

0010 In the embodiment shown in FIG. 2, the slit 22 is used to control the luminance distribution of the light source. Instead of the slit 22, white paint may be used to scatter light. this Such examples are shown in FIGS. 4 and 5. 30 in the figure is white paint powder, which is slightly coated on the outer surface of the light source tube 6. Apply in granular form. The white paint concentration distribution in the x-axis direction is high at the center as shown in Figure 4. Low at the periphery, light from the center is scattered by white paint, and light from the periphery goes straight. In this way, the illuminance distribution in the x-axis direction of the liquid crystal panel 2 is eliminated. On the other hand, the light source tube Along the circumferential direction of the liquid crystal panel 6, as shown in FIG. Correspondingly, the white paint concentration is increased near the 0 degree orientation of the light source tube 6, and the white paint concentration is increased around the y-axis direction. The corresponding orientation lowers the density near 90 degrees vertically. In this way, the LCD panel It scatters the light to the center of the screen 2, reducing the illuminance, while not scattering the light at the periphery. A part of the light scattered from the center is added to increase the illuminance.

[0011] Control of the illuminance distribution using the white paint in Figures 4 and 5 is based on the main body 4 of the thin lighting device and the light source. This can also be achieved by installing a film coated with white paint or a transparent plate between the tube 6. Ru. Such an example is shown in FIG. In the figure, 40 is a filter coated with white paint. For example, it is attached to the end of the thin lighting device main body 4 to control the amount of light from the light source 6. . The distribution of white paint concentration is shown in FIG. The distribution of paint concentration is the same as the examples shown in Figures 4 and 5. For each of the x-axis and y-axis, make it lower at the periphery, higher at the center, and move toward the center. scatters light to increase the amount of light to the surrounding area.

0012

[Effect of the idea]

This idea solves the problem of illuminance distribution on the LCD panel on the light source side of the thin lighting device. can.

[Brief explanation of drawings]

[Figure 1] Diagram showing the distribution of fluorescent paint concentration in the light source tube used in the example

[Fig. 2] Perspective view of main parts of the second embodiment

[Fig. 3] Plan view of main parts of a modification of the second embodiment

[Figure 4] Diagram showing the x-axis direction distribution of white paint concentration in the third example

[Figure 5] Diagram showing the distribution of white paint concentration in the y-axis direction of the third example

[Figure 6] Diagram showing the light scattering plate and white paint concentration distribution of the fourth example

[Figure 7] Side view of a conventional liquid crystal display element

[Figure 8] Characteristic diagram showing the illuminance distribution of a conventional liquid crystal display element

[Explanation of symbols]

2 Color LCD panel 4 Thin lighting device body 6,16 Light source tube 20,26 mask 22, 28 slit 30 White paint 40 film

Claims (1)

[Scope of utility model registration request] 1. A liquid crystal display element provided with a thin illumination device, in which a light source tube is disposed on one main surface side of a liquid crystal panel, a light source tube is disposed on an end surface side, and a thin illumination device main body is disposed on the main surface side, wherein the thin The lighting device is a liquid crystal display element characterized in that the light intensity distribution of incident light from the light source tube to the thin lighting device main body is high at both ends and low at the center.