JP2895581B2 - Color liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device, and more particularly, to a smoothing of a color filter surface used in a liquid crystal display device.

[Prior Art] A color filter used in a color liquid crystal display device is manufactured by a dyeing method (Japanese Patent Application Laid-Open No. 60-55,301) and a pigment dispersion method (Japanese Patent Application Laid-Open No.
No. 2,449), No. 2-47,605), and a printing method (Japanese Patent Laid-Open No. 60-98,
No. 482). In any of these manufacturing methods, a gap remains between pixels, and the surface of the color filter is not smooth. If the surface of the color filter is not smooth, it becomes difficult to form a transparent electrode such as an ITO film laminated on the filter, and troubles such as disconnection of the transparent electrode occur.

It is known to provide a smoothing film made of a synthetic resin on the surface of a pixel in order to obtain a color filter having a smooth surface (JP-A-61-6624). In this technique, a gap between pixels is filled with a synthetic resin in a smoothing film to smooth a color filter.

However, since the gap between the pixels is thin and deep, it is difficult to completely smooth the color filter with a smoothing film of synthetic resin. In practice, corresponding unevenness is left between pixels on the surface of the color filter. Therefore, it is necessary to further improve the technique for smoothing the surface of the color filter.

[Problem of the Invention] An object of the present invention is to improve the surface smoothness and the surface hardness of a color filter of a liquid crystal display device. When the surface of the color filter is smoothed and the hardness is increased, lamination of the transparent electrodes becomes easier,
And its reliability is high. Further, when the surfaces of the color filters are smoothed, the thickness of the liquid crystal layer becomes uniform, and the display quality is improved.

[Constitution of the Invention] The color liquid crystal display device of the present invention has a molecular weight of 20,000 in a pixel region in which a color filter is provided on one of the pair of light-transmitting substrates with a liquid crystal layer interposed therebetween. A smoothing film made of a synthetic resin having a low molecular weight of less than and a smoothing film made of the same monomer as the synthetic resin and having a high molecular weight of 20,000 or more are sequentially coated by a transfer method, and the smoothness of the pixel region is reduced. Is set to 0.1 μm or less.

In general, a low-molecular-weight synthetic resin is soft, and it is easy to uniformly fill the space between pixels. The high molecular weight synthetic resin is hard, and it is difficult to uniformly fill small gaps. Therefore, the gap between the pixels is filled with a low molecular weight synthetic resin, and the remaining unevenness is smoothed with a high molecular weight synthetic resin. The high molecular weight smoothing film on the color filter surface becomes a hard surface film and improves the hardness of the color filter surface.

The smoothing film may be a two-layer film of a low molecular weight film and a high molecular weight film, or may be a three-layer film or a four-layer film. In this case, the molecular weight of the smoothing film is sequentially increased from the side closer to the pixel to the side farther from the pixel. Of course, the molecular weight of the smoothing film may be continuously increased from the side closer to the pixel to the side farther from the pixel.

The molecular weight of the smoothing film is less than 20,000 on the side closer to the pixel, more preferably 10,000 or less, and 20,000 or more on the side farther from the pixel, and is selected according to the width between pixels and the depth thereof. . The narrower and deeper the space between the pixels, the smaller the molecular weight of the low molecular weight smoothing film and the smaller the unevenness on the surface of the low molecular weight smoothing film. The molecular weight of the high molecular weight smoothing film is determined according to the degree of unevenness remaining in the low molecular weight smoothing film and the required surface hardness.

As a material of the smoothing film, for example, an acrylic resin having high transparency may be used. In addition, a polyimide resin having a high heat resistance but coloring, an epoxy resin, a urethane resin, or the like may be used.
The type of synthetic resin used improves the compatibility between the resins,
In order to facilitate manufacture, the side near and far from the pixel is of the same type (the same monomer). For the production of smoothing films,
What is necessary is just to use the transfer from the film with low adhesive force with resin.

Embodiment FIG. 1 shows an embodiment. In the figure, reference numeral 2 denotes a transparent substrate such as glass, and reference numeral 4 denotes a black matrix made of a metal film such as Cr. Pixels 6, 8, and 10 are pixels, for example, pixel 6 represents red, pixel 8 represents green, and pixel 10 represents blue. These pixels 6, 8, and 10 are manufactured by a dyeing method, a pigment dispersion method, a printing method, or the like. Here, since the pixels cannot be manufactured so as to be completely adhered to each other, a gap is generated between the pixels.

Reference numeral 12 denotes a low-molecular-weight smoothing film having a molecular weight of, for example, less than 20,000, more preferably 10,000 or less. In the smoothing film 12,
For example, an acrylic resin is used. The type of resin is not limited to acrylic, but a polyimide resin, an epoxy resin, a urethane resin, or the like may be used. Since the low molecular weight smoothing film 12 has a low molecular weight of the synthetic resin and a low viscosity at the time of formation, the low molecular weight smoothing film 12 easily enters the gaps between the pixels 6, 8, and 10, and substantially smoothes the surface.

Reference numeral 14 denotes a high molecular weight smoothing film, preferably a synthetic resin of the same type as the low molecular weight smoothing film 12. The molecular weight of the high molecular weight smoothing film 14 is, for example, 20,000 or more. High molecular weight smoothing film 14
In this case, the remaining unevenness is smoothed by the low molecular weight smoothing film 12, and the surface of the color filter becomes a hard surface film.

The smoothing films 12, 14 are made of a Teflon film or the like.
Apply synthetic resin, which is the material of No. 14, and apply this film to the pixels
Pressed onto 6,8,10 and pressurized uniformly to apply synthetic resin to pixels 6,8,10
It is sufficient to transfer the film so as to fill the gaps of 10 and then peel off the film such as Teflon. The smoothing films 12 and 14 are separately formed one by one.

16 is an ITO film (In) laminated on the high molecular weight smoothing film 14.
—Sn oxide film) and 18 is a liquid crystal layer. The liquid crystal layer on the opposite side of the transparent electrode 16 includes another transparent electrode (not shown) and its substrate, and the thickness of the liquid crystal layer 18 is regulated by a spacer (not shown). On the back surface of the glass substrate 2, there is a backlight light source (not shown), and light from the light source passes through the color filter and the liquid crystal layer 18 and exits through the opposite glass substrate.

FIG. 2 is an enlarged view of the embodiment. The thickness of each of the pixels 6, 8, and 10 is, for example, about several μm, and the gap between the pixels is deep. Therefore, it is difficult to completely perform smoothing using only the low molecular weight smoothing film 12. The remaining concavities and convexities are smoothed by a smoothing film 14 having a high molecular weight. The high molecular weight smoothing film 14 has high hardness because a synthetic resin having a large molecular weight is used. Therefore, a hard smoothing film 14 remains on the surface of the color filter. The smoothing films 12 and 14 are collectively referred to as a smoothing film 15.

FIG. 3 shows a conventional color liquid crystal display device. In this color liquid crystal display device, since the smoothing film 01 is composed of one layer, it is difficult to simultaneously satisfy the two requirements of surface hardness and smoothness. In the case of one layer, the surface of the smoothing film 01 is significantly uneven.

Table 1 shows the smoothness of the color filter surface when acrylic resin was used for the smoothing films 12, 14, and 01. The average molecular weight of the low molecular weight smoothing film 12 is about 8,000, the average molecular weight of the high molecular weight smoothing film 14 is about 25,000, and the smoothing film 01 of the comparative example.
Has an average molecular weight of about 12,000. The film thickness of the smoothing films 12,01 is about 1 μm above the pixels 6, 8, and 10, and the film thickness of the smoothing film 14 is about 0.3 μm. As is clear from Table 1, the irregularities on the surface of the color filter in the example are reduced to about 1/3 to 1/5 of the conventional example.

[Effect of the Invention] In the color liquid crystal display device of the present invention, the smoothness of the surface of the color filter is improved and the hardness of the surface is improved. As a result, the lamination of the transparent electrodes becomes easy, and a highly reliable electrode can be obtained. Next, by adjusting the average height of the surface of the color filter, the thickness of the liquid crystal layer can be made uniform and the display quality can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the embodiment, and FIG. 2 is an enlarged cross-sectional view of a main part thereof. FIG. 3 is a sectional view of a conventional example. In the figure, 2 ... substrate, 6, 8, 10 ... pixels, 12 ... low molecular weight smoothing film, 14 ... high molecular weight smoothing film.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1333

Claims (1)

(57) [Claims] 1. A low molecular weight synthetic resin having a molecular weight of less than 20,000 is provided in a pixel region in which a color filter is provided on one of the pair of translucent substrates having a liquid crystal layer interposed therebetween. A color liquid crystal in which a smoothing film and a smoothing film having a high molecular weight of 20,000 or more with the same monomer as the synthetic resin are sequentially coated by a transfer method, so that the smoothness of the pixel region is reduced to 0.1 μm or less. Display device.