JP2799638B2 - Color liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display panel and, more particularly, to a color liquid crystal display device which performs multicolor display.

[0002]

2. Description of the Related Art Conventionally, as a color filter, a mordant layer made of a hydrophilic polymer substance such as gelatin, casein, glue or polyvinyl alcohol is provided on a substrate, and the mordant layer is dyed with a dye to form a colored layer. Staining color filters are known. Further, a color filter using a coloring resin in which a certain coloring material is dispersed in a transparent resin is also known. In the color liquid crystal display element, a large number of pixels functioning as optical shutters are formed on the red, green, and blue filters thus formed, and color display is performed using three colors as one picture element. To display as many colors as possible in such a method, gradation control for each pixel is required, and in gradation control using only two values, one picture element can be displayed up to eight colors in principle. Japanese Patent Application Laid-Open No. 2-118521 has proposed that one picture element be formed with four colors (white is added).

[0003]

A conventional example will be described below. FIG. 5 is a configuration diagram of a conventional picture element that drives four pixels in a binary manner to display 16 colors. Red (R) pixel 1, green (G) pixel 2, blue (B) pixel 3, and Each of the white (W) pixels 4 has the same display area. FIG. 4 shows the spectral transmittance of each color.
In this case, the relationship between the combination of the transmissive and non-transmissive states of each pixel and the displayed color is as shown in Table 1.

[0004]

[Table 1] In Table 1, the mark “○” indicates the “transmission” state.

[0005] However, in this conventional 16-color display, No. 3 in which white is added is used. No. 9 to No. 9 Display colors up to 13 light cyan are inferior in image quality due to lack of sharpness. In addition, the combination No. 4
No. I and No. 8 has almost the same display color, and has a disadvantage that only 15 colors can be distinguished in practice.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and a color liquid crystal display device capable of displaying a multicolor display which can be clearly distinguished by human eyes even in a binary drive system. The purpose is to provide.

[0007]

In order to achieve the above object, the present invention provides a color liquid crystal display device having a picture element composed of four pixels of red, green, blue and white on a substrate. Are composed of pixels having the same display area of red, green, and blue, but different display areas of only white ,
-16 colors that can be distinguished from 4 colors, white and white
Characterized in that way the.

[0008]

The function and effect of the present invention will be described below in detail by taking a color liquid crystal panel as an example.

In the display using the three primary colors of light (R, G, B), the number of expressible colors is limited by the gradation of each color. The color display method using liquid crystal uses R, G, B
An electrode is further formed on the filter to provide a so-called optical shutter for turning on or off light in a minute area. A general method for controlling the gradation is to control the voltage applied to the upper and lower electrodes constituting the optical shutter. More specifically, gradation is realized by selecting an intermediate value between a voltage value that completely turns on and a voltage value that completely turns off. However, in reality, there is no linear relationship between the applied voltage value and the amount of transmitted light, so that fine gradation control is difficult. Further, the system and circuits for controlling the driving become complicated, leading to a significant increase in cost. In view of this, the above-described method has been proposed in which white is added to three primary colors, which is capable of displaying 16 colors while being binary driven.

However, as described above, the expression of colors is basically a mixture of three primary colors, and the addition of only white lacks sharpness when discriminated by human eyes. That is, No. 1 in Table 1 The display colors obtained by adding white shown in 9 to 14 are too close to the point W in the chromaticity diagram shown in FIG.

According to the present invention, the pixel display area of four colors is conventionally made the same, but the pixel display area of only white is reduced, so that the sharpness of the display color can be improved. For example, white represented by a mixture of three pixels of R, G, and B and white represented by one white pixel have substantially the same light amount if the pixel areas are equal, and will be seen by human eyes as the same white. This means that one display color has been reduced. Also, in the case of a display color in which white is added, if the pixel area is the same, the amount of white light is large, and as a result, the color becomes too pale and lacks sharpness.
Also in this case, by reducing the white pixel area, a color display that can be identified as 16 colors and has sharpness can be realized.

[0012]

Embodiments of the present invention will be described below.

FIG. 1 shows the structure of one pixel of a color filter used in a color liquid crystal display device according to one embodiment of the present invention. Parts common or corresponding to the conventional example of FIG. 5 are denoted by the same reference numerals. The element shown in FIG. 1 includes an R pixel 1, a G pixel 2 and a B pixel 3 among four pixels constituting one picture element.
3 pixels have a filter area of 200 μm square and W pixels 4
Only 160 μm square. That is, the area ratio between the W pixel and the other pixels is about 2/3.

The color filters shown in FIG. 1 are shown in FIGS.
It was manufactured by the method shown in (e).

First, as shown in FIG. 2A, a photosensitive resin mainly composed of polyamide (Ube Industries, Ltd. in this embodiment) was formed on a glass substrate (thickness: 1.1 mm) 5 by a spinner method. PA1000C) was applied to form a photosensitive resin layer 6. Next, this was pre-baked at 85 ° C. for 10 minutes, and further exposed using a photomask 7 (FIG. 2B), and a desired portion 6a of the photosensitive resin layer 6 was light-cured (FIG. 2C). ). Thereafter, portions other than the desired portion 6a are removed by a development process (FIG. 2D).
A white (transparent) pixel 4 shown in (e) was formed. Next, through the same steps, pixels 1 to 3 of other three colors, red (R), green (G) and blue (B) were formed as shown in FIG. The order of forming the other three colors changes depending on the characteristics of the material used, that is, the adhesion and the size of the pigment included. As these three color pixel materials, for example, PA-1012 (manufactured by Ube Industries, Ltd.) in which a pigment is dispersed in a photosensitive resin mainly composed of polyamide can be used.

A protective layer is provided on the color filter formed as described above, and an ITO film and a metal auxiliary electrode film are further provided thereon, and each is patterned to form a stripe electrode, and an insulating layer and an alignment film layer are formed. The gap amount between the processed substrate and the counter substrate on which the counter electrode is mounted is 1.
Bonding was performed at a value between 0 and 1.5 μm, and a ferroelectric liquid crystal was injected into the gap and sealed. The result of measuring the color characteristics of this panel is shown in the chromaticity diagram of FIG. FIG.
As is clear from the comparison between FIG. 6 and FIG. 6, the color characteristics when white is mixed compared with the panel of FIG. 5 in which white is the other three colors and has the same area (points indicated by に in FIG. 3)
Moved away from the white (W) point, and even when recognized by the human eye, the color was clearly perceived as a distinct color.

[0017]

As described above, according to the present invention,
In a color liquid crystal display device in which one pixel is composed of four colors (R, G, B, W), the display area of only white (W) is made smaller than the other three colors, so that a clearer image is obtained when mixed with white. Color display as a light color was realized. In addition, when a photosensitive resin having transmittance characteristics as shown in FIG. 4 was used, an optimum color display by human eyes was obtained when the area ratio was 3: 2. In a color filter in which four colors are arranged in a stripe in a line, the same effect was obtained by reducing the area of only white.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of one picture element of a color filter used in a color liquid crystal display device according to one embodiment of the present invention.

FIG. 2 is an explanatory view showing an example of a method for manufacturing the color filter of FIG.

FIG. 3 is a chromaticity diagram of the color filter of FIG. 1;

FIG. 4 is a spectral transmittance characteristic diagram of a colored resin used for a color filter.

FIG. 5 is an explanatory diagram showing a configuration of one picture element of a conventional color filter.

FIG. 6 is a chromaticity diagram of the color filter of FIG. 5;

[Explanation of symbols]

1: R pixel, 2: G pixel, 3: B pixel, 4, 6a: W pixel, 5: glass substrate, 6: resin film, 7: photomask.

Claims (2)

(57) [Claims] 1. A color liquid having picture elements composed of four pixels of red, green, blue and white on a substrate.
In crystal display device, each pixel is red, green and equal display area of blue, Ri Do of pixels having different display areas only white, the red, green, blue
And 16 colors that can be identified by the four colors white and white
Color liquid crystal display element, characterized in that the so that. 2. The color liquid crystal display device according to claim 1, wherein the white display area is arranged to be smaller than 表示 of the display area of another color.