JPH0412323A - Color liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve the color balance and visual angle and to expand the range of color reproduction by providing a filter which interrupts blue light transmitted through phosphors for wavelength conversion and filters which improve the color purity on the phosphors. CONSTITUTION:On a polarizing plate, a phosphor 11 which converts blue light into red light and a phosphor 12 which converts the blue light into green light are printed corresponding to each picture element. The filter 13 which interrupts the blue light is provided on those phosphors 11 and 12, and the red purity improving filter 14, green purity improving filter 15, and the phosphor 17 for wavelength conversion which improves the blue purity of a blue picture element are further provided. Consequently, the blue light has large visual field dependency as well as a conventional liquid crystal display panel, so the phosphor 17 for improving the blue impurity is provided on the surface of the liquid crystal display panel to improve the visual field dependency.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of color liquid crystal display panels used in display devices such as OA equipment, the purpose is to improve color balance and viewing angle characteristics, and expand the color reproduction range. One or more wavelength converting phosphors that convert blue to red or green are arranged corresponding to each pixel on the display surface side of the liquid crystal display panel where the display is obtained, allowing multicolor and color display. In the color liquid crystal display panel, a filter for blocking blue light transmitted through the phosphor and a filter for improving color purity are provided on the wavelength conversion phosphor.

Furthermore, the configuration is such that, corresponding to the blue pixel, a phosphor for wavelength conversion and/or a neutral density filter for attenuation are provided to improve the purity of blue color.

[Industrial application field]

The present invention relates to improvements in color liquid crystal display panels used in display devices such as office automation equipment.

[Conventional technology]

As shown in FIG. 2, the structure of a conventional color liquid crystal display panel is such that a color filter 2 is disposed on a glass substrate 1.
A substrate 1 on which an overcoat layer 3, a transparent electrode 4 using ITO, and an alignment film 5 are sequentially disposed, and a transparent electrode 4'
A compensation panel for chromaticity compensation (not shown) or a compensation film is combined with an STN type drive panel filled with a liquid crystal 6 between the counter substrate 1' on which only the alignment film 5' is disposed. It was used.

Further, in order to improve the contrast and viewing angle characteristics, as shown in FIG. 3, a phosphor 8 that converts blue to red and a phosphor 9 that converts blue to green are disposed on the liquid crystal display panel 7, and a blue backlight 10 is provided. A pseudo-light-emitting display panel has been devised that switches single-wavelength light from a source and excites a phosphor 8.9 with the switched light (Japanese Patent Application Laid-Open No. 1983-1993).
-194227, JP-A-62-194228)
.

[Problem to be solved by the invention]

In the conventional liquid crystal display panel shown in Fig. 3, the liquid crystal deteriorates quickly when ultraviolet rays are used as the monochromatic light for excitation of the phosphor, making it extremely impractical. There have been problems in that the range of color reproduction is extremely small due to the poor conversion efficiency of the phosphor, the low blue absorption coefficient of the phosphor, and the large amount of blue light transmitted.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a color liquid crystal display device that improves color panoramic and viewing angle frames and expands the range of color reproduction.

[Means to solve the problem]

In order to achieve the above object, the color liquid crystal display panel of the present invention includes one or more wavelength converting phosphors for converting blue to red or green on the display surface side of the liquid crystal display panel that provides a blue-black display. In a color liquid crystal display panel that performs multicolor and color display by arranging a phosphor 1 corresponding to each pixel, the phosphor 1 is placed on the wavelength conversion phosphor 11 and 12.
The present invention is characterized in that it is provided with a filter 13 that blocks blue light that has passed through 1.12.

Further, it is characterized in that a filter 14.15 for improving color purity is provided on the phosphor 11, 1.2 for wavelength conversion.

Furthermore, it is characterized in that, corresponding to the blue pixel, a phosphor 17 for wavelength conversion to improve the purity of blue color and/or a neutral density filter 18 for attenuation are provided.

[For production]

As with conventional LCD panels, blue light has strong viewing angle dependence, so by providing a phosphor (becomes a light scattering layer) 17 on the surface of the LCD panel to improve the purity of blue color, the viewing angle dependence can be reduced. can be improved. Further, since the conversion efficiency of the phosphor is low, the red intensity is extremely low compared to the blue intensity, but this point can be balanced by providing a neutral density filter 18 for light attenuation on the blue pixel. In addition, for the point where blue light is not sufficiently absorbed by the phosphors 11 and 12 and is transmitted, the phosphors 11 and -
This problem can be solved by providing a blue cutoff filter 13 on top of 12. Furthermore, color purity can be improved by passing the phosphor 11.12 through a filter 14.15 after it has developed a color.

〔Example〕

FIG. 1 shows an embodiment of the present invention.

In the figure, 10 is a liquid crystal display panel, and this liquid crystal display panel was created as follows. That is, an alignment film was applied to a glass substrate coated with a transparent conductive film, dried and cured at about 100° C., and then cured. As the alignment film, RN721 (manufactured by Nichichi Kagaku) was used. R
N721 can obtain good alignment characteristics when cured at 250°C. After that, a sealing material was printed, the same process was performed, and the spacer was applied to the opposite substrate, which was bonded to the counter substrate, and liquid crystal was injected.

This liquid crystal panel displays a blue-black display, and based on the results of theoretical calculations and experiments, the twist angle is set at 240 to 270 degrees Celsius.
A sufficiently good blue-black display panel for use in the present invention was obtained by using a crossed nicol polarizing plate in which the Δn-d of the panel was in the range of 500 to 600 nm.

As shown in Fig. 1, dried powder of Rhodamine 6G is placed on the polarizing plate as a phosphor 11 that converts blue to red, and brilliant sulfoflavine FF is placed as a phosphor 12 that converts blue to green. Printed according to pixels. In the selected pixel, the light transmitted through the liquid crystal panel 10 is converted from blue to red or green. Therefore, in this liquid crystal display panel, a multicolor display of three full colors is possible as a pseudo light-emitting type display, but the wavelength converting phosphors 11 and 12 used in this example do not completely absorb the blue color and have some color. Because it is transparent, the color reproduction range is limited to the vicinity of blue. Therefore, in this example, in order to prevent the transmission of blue light, the phosphor 1
A filter 13 for blocking blue light was provided above 1 and 12. This greatly expanded the color reproduction range and provided a full-color display sufficient for practical use.

Furthermore, since wavelength-tunable phosphors generally have broad emission spectra, in this embodiment, a red purity improving filter 14 and a green purity improving filter 15 are provided to improve color purity. This 1: A better color reproduction range can be obtained. In this case, red and green light is emitted, but blue light is seen directly from the light transmitted from the backlight 16, so the viewing angle dependence differs depending on the color. Therefore, in this embodiment, a wavelength conversion phosphor 17 that improves the purity of blue color is provided in the blue pixel. In addition, the phosphor 11 that converts blue to red has poor conversion efficiency, and the brightness of red is about 1710th that of blue, and sufficient color mixing is not possible. By providing a neutral density filter 18, brightness can be corrected and color mixing can be performed well. As a result of the above, a color liquid crystal display panel capable of good full-color display was realized.

Note that it is desirable that the spectrum of the backlight 16 matches the absorption band of the phosphor, and good results were obtained with a half-width of 50 nm or less in the range of 400 to 490 nm.

〔Effect of the invention〕

As explained above, according to the present invention, a color purity improving filter and a blue blocking filter are provided on the color converting phosphor on the red pixel and the green pixel, and a color purity improving phosphor and a blue blocking filter are provided on the blue pixel. By providing a neutral density filter for light, the color balance and viewing angle characteristics are improved, and the range of color reproduction can be expanded, which is a great effect.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a cross-sectional view showing a conventional color liquid crystal display panel, and Fig. 3 is a diagram showing a conventional color liquid crystal display panel with improved contrast and viewing angle characteristics. be. In the figure, 10 is a liquid crystal display panel, 11 is a wavelength conversion phosphor (blue → red), 12 is a wavelength conversion phosphor (blue → green), 13 is a blue cutoff filter, 14 is a red purity improvement filter, and 15 is a red purity improvement filter. 16 is a backlight, 17 is a phosphor for improving blue purity, and 18 is a neutral density filter.

Claims (1)

[Claims] 1. On the display surface side of a liquid crystal display panel that provides a blue-black display, one or more wavelength converting phosphors for converting blue into red or green are disposed corresponding to each pixel. In a color liquid crystal display panel that displays multiple colors and colors, a filter (1) is placed on the wavelength conversion phosphor (11, 12) to block the blue light transmitted through the phosphor (11, 12).
3) A color liquid crystal display panel. 2. A color liquid crystal display panel according to claim 1, characterized in that a filter (14, 15) for improving color purity is provided on the phosphor (11, 12) for wavelength conversion. panel. 3. In the color liquid crystal display panel according to claim 1 or 2, a wavelength conversion phosphor (17) for improving the purity of blue color corresponding to the blue pixel, and a neutral density filter (18) for light attenuation. A color liquid crystal display panel characterized by having either or both of the following.