JP3536447B2 - Color liquid crystal display - 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 liquid crystal display device.

[0002]

2. Description of the Related Art A birefringence control system, a color filter system and the like are known as a color generating function of a liquid crystal display device. Among them, the color filter method is R (red),
A micro color filter composed of three primary colors of G (green) and B (blue) is used, and color display is realized by combining these.

Generally, conventional color filters are formed in a simple polygonal shape, for example, a quadrangle. The color filters are arranged corresponding to the pixels, and as a concrete arrangement method, a stripe method, an oblique mosaic method, a triangular mosaic method (dot arrangement method), etc. are known. Of these, the triangle mosaic method is said to be suitable for obtaining the highest image quality.

Further, a black mask is generally arranged between the pixels of the liquid crystal display element in order to improve visibility. The black mask is formed by, for example, arranging a mask using a carbon-based dye or a metal layer as a base.

[0005]

However, the conventional black mask has a problem that the manufacturing process is complicated and the yield of the device is lowered. Therefore, as a simple method of manufacturing a black mask, a method of manufacturing a pseudo black mask (pseudo black mask) by stacking adjacent color filters and mixing colors in the overlapping portions is conceivable. FIG. 5 shows an example in which square color filters are arranged so as to form a pseudo black mask by the triangle mosaic method. Here, reference numeral 33R is a red color filter, 33G is a green color filter, 33
B indicates a blue color filter, respectively.

However, when the color filters are arranged as shown in FIG. 5, a portion in which the color filters 33R, 33G and 33B are overlapped in three layers is produced as shown in the sectional view (a view taken along the arrow AA) in FIG. As a result, a large step is formed between the pixel and the central portion (one layer) of the pixel. This step also affects the shape of the surface of the alignment film on the color filter 33, and a protrusion corresponding to the three-layer portion is formed on the surface of the alignment film.

When a protrusion is formed on the surface of the alignment film, particularly in the case of STN liquid crystal, the liquid crystal layer thickness D, the liquid crystal pitch P, and the liquid crystal twist angle φ maintain a relationship of D / P = φ / 2π. There is a problem that it becomes impossible and the alignment failure becomes remarkable.

The present invention has been made in view of the above situation, and while improving the visibility by a pseudo black mask,
It is an object of the present invention to provide a color liquid crystal display device that can reduce liquid crystal alignment defects.

[0009]

In order to achieve the above object, a color liquid crystal display device of the present invention comprises a first substrate on which a first electrode, color filters of a plurality of colors and a first alignment film are formed. A second substrate having a second electrode facing the first electrode and a second alignment film, and the first and second substrates.
And a liquid crystal disposed between the alignment films of each of the color filters, and each of the color filters has a square cutout at two adjacent two corners of the square, and the color filters of different colors are partially It is characterized in that the pseudo black masks are overlapped with each other and that the overlapped portions are always arranged in two layers.

[0010]

According to the liquid crystal display device having the above-described structure, the overlapping portions of the color filters do not have to have two layers and have three or more layers. Therefore, the unevenness of the color filter surface is reduced, and the alignment failure of the liquid crystal due to the unevenness of the color filter surface is reduced. Further, the color mixing portion due to the overlapping of the color filters acts as a pseudo black mask, and the visibility of the display image is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a sectional structure of an STN liquid crystal display element according to an embodiment of the present invention. As shown in FIG. 1, this liquid crystal display element is composed of a pair of transparent substrates 11 and 12 joined by a sealing material SC and an STN liquid crystal 13 sealed between the pair of substrates 11 and 12. Liquid crystal cell 16
And the polarizing plates 14 and 15 arranged with the liquid crystal cell 16 interposed therebetween.
And consists of

The lower substrate (TFT substrate) 11 has a TFT (thin film transistor) 21 as a switching element.
The pixel electrodes 22 are arranged in a matrix, and an alignment film 23 that has been subjected to an alignment treatment in a predetermined direction is arranged thereon.

The source electrode of each TFT 21 is connected to the corresponding pixel electrode 22, the gate electrode of the TFT 21 in each row is connected to the corresponding gate line, and the drain electrode of the TFT 21 in each column is connected to the corresponding data line. . The pixel electrode 22 is formed of a transparent conductive film made of ITO or the like, and is arranged at a position shifted by ½ pitch for each row.

A counter electrode 31 is formed on the upper substrate (counter substrate) 12. Color filters 33 (33R, 33G, 33B) of RGB colors are arranged in each pixel region of the counter electrode 31, that is, in a position facing the pixel electrode. The color filter 33 is made of acrylic resin or the like having a thickness of about 1.0 μm, and is made of R, G, or
It is colored in either B. The shape and arrangement of the color filter 33 will be described later.

Color filters 33 (33R, 33G, 3)
3B), an overcoat layer (protective layer) 34 is arranged, and an alignment film 36 made of polyimide or the like is formed thereon.
Are formed.

The STN liquid crystal 13 is composed of a chiral nematic liquid crystal, and is 180 ° from the substrate 11 toward the substrate 12 according to the alignment treatment applied to the surfaces of the alignment films 23 and 36.
Approximately 270 ° is twisted and oriented.

The polarizing plates 14 and 15 are arranged so that their optical axes are located in predetermined directions with reference to the direction of the alignment treatment of the alignment film 23.

Next, the shape and arrangement of the color filter 33 will be described with reference to FIGS. Each color filter 3
3 (33R, 33G, 33B), as shown in FIG.
It has a shape in which two adjacent two corners of a quadrangle are cut out into a quadrangle. In other words, the color filter 33 has a shape in which the small second rectangle projects from one side of the large first rectangle.

The side L1 of the cutout has a length equal to the spacing in the row direction of pixels arranged in a matrix (the width of the pseudo black mask extending in the column direction), and the side L2 of the cutout is It has a length equal to the spacing in the column direction between pixels arranged in a matrix (width of the pseudo black mask extending in the row direction).

Next, the color filter 3 having the shape shown in FIG.
The arrangement method of No. 3 will be described with reference to FIG. Note that, in FIG. 3, hatching and dots are shown in order to distinguish the color filters 33 of the respective colors. As shown in FIG. 3, the color filter 33 includes R, G, B, and
The color filters 33 in the adjacent rows are arranged in the order of R, ...

The color filter 33 has a side L 4 in the row direction, which includes a side L 3 having the cutout portion of the red color filter 33 R and a side L 4 facing the side L 3 having the cutout portion of the green color filter 33 G. Are arranged so as to overlap each other by the length of the side L1 (the second rectangle is arranged so as to overlap the first rectangle), and similarly, the side L of the blue color filter 33B is arranged. sides overlap by a length of a side L1 of the notches in the side portion including a side L3 of the green color filter 33G including 4, the side edge portion including the edge l3 comprises sides L 4 of the red color filter 33R It is arranged so as to overlap the portion by the length of the side L1 of the cutout portion.

Further, in the column direction, a side portion including a side L5 perpendicular to the side L3 of the color filters 33 of two different colors and a side portion including a side L5 of the color filters 33 of other colors in the adjacent row. Are arranged so as to overlap each other by the length of the side L2.

FIG. 1 is a sectional view taken along the line BB shown in FIG.
4 and a sectional view taken along the line CC is shown in FIG. As shown in FIGS. 1 and 4, according to the structure and the arrangement of the color filters 33 of this embodiment, the cutout portion of each color filter 33 overlaps with the other two color filters 33, so that 2 even at the overlap
It is a layer and never becomes three layers. Therefore, the irregularities on the surface of the color filter 33 can be suppressed to be small, and the irregularities on the surface of the alignment film can be suppressed to be small, and the liquid crystal can be stably aligned.

Further, only one color filter 33 is arranged on each pixel (opposing portion of the pixel electrode 22) to color light passing through each pixel. Further, an overlapping portion of the two color filters 33 is arranged in the peripheral portion of each pixel and functions as a pseudo black mask.

The color filter 33 having such a structure and arrangement is manufactured by using a generally known manufacturing method such as a printing method, a photolithography method and a dyeing method.
Can be easily manufactured by sequentially forming.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, the order of arranging the colors of the color filter 33 is arbitrary. Further, in the configurations of FIGS. 1 and 3, the side portion of the green color filter 33G is located above the side portion of the red color filter 33R, and the blue color filter 33B is located in the red and green color filters 33.
It has been described that it is located on the side of the R, 33G. This is an example of the case where the color filter 33 is formed on the substrate 12 in the order of R, G, B, and another overlapping structure may be adopted. That is, the manufacturing order of the color filters 33 of each color may be arbitrarily changed.

In the above embodiment, the present invention has been described by taking the active matrix type liquid crystal display element as an example. However, the present invention is concerned with the scanning electrodes and the signals arranged so as to intersect each other on the inner surfaces of the pair of substrates facing each other. The present invention can be similarly applied to a simple matrix (passive matrix) type liquid crystal display device having electrodes. In this case, the pixel is 1 per row
For example, the signal electrode is meandered so as to be shifted by ½ pitch, and the color filter is arranged on the scanning electrode or the signal electrode. The shape and arrangement of the color filter are the same as those shown in FIGS.

The present invention is particularly effective for STN liquid crystals that are prone to alignment defects due to the unevenness of the alignment film surface, but other types of liquid crystal display elements using a pseudo black mask,
For example, it can be similarly applied to a TN element or the like.

[0029]

As described above, according to the present invention, the overlapping portions of the color filters are always two layers, the unevenness of the color filter surface can be reduced, and the alignment failure of the liquid crystal can be reduced. Therefore, a high quality image can be displayed. Moreover, since the overlapping portion of the color filters forms a pseudo black mask, the visibility of the display image is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a color liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a diagram showing a shape of a color filter according to an embodiment of the present invention.

FIG. 3 is a layout view of a color filter according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along the line CC of FIG.

FIG. 5 is a layout view of a conventional color filter.

6 is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

11, 12 ... Substrate, 13 ... STN liquid crystal, 14, 15 ...
-Polarizing plate, 16 ... Liquid crystal cell, 21 ... TFT, 22 ... Pixel electrode, 23 ... Alignment film, 31 ... Counter electrode, 33 ... Color filter, 34 ... Over Coat layer, 36 ... Alignment film

Claims (3)

(57) [Claims] 1. A first substrate on which a first electrode, a color filter of a plurality of colors, and a first alignment film are formed, a second electrode facing the first electrode, and a second alignment film. In a color liquid crystal display device comprising a second substrate on which is formed and a liquid crystal disposed between the first and second alignment films, each of the color filters is a quadrangle of two adjacent corners. It has square cutouts at some places, and parts of the color filters of different colors overlap each other to form a pseudo black mask, and the overlapping parts are arranged so as to be always two layers.
A color liquid crystal display device characterized by the above. 2. The color filter includes color filters of three primary colors, and the cutout portions of the color filters of the respective colors and the overlapping portions of the color filters of the other two colors are arranged to overlap each other. The color liquid crystal display element according to claim 1. 3. The color filter includes a color filter of three primary colors, and the color filter includes two color filters of a first color.
A second side portion opposite the first side portion having a One notch, the length of the first side portion with two notches and the notch portions of the color filter of the second color overlapping a first overlapping each other of said first and second color filters
The third side portion in a direction perpendicular to the second side portion, the vertical to said first and second sides of the third color filter
The color liquid crystal display element according to claim 1, wherein the third side portion is arranged so as to overlap by the length of the cutout portion.