JPH07140449A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To expand a margin for production and to improve transmission efficiency of incident light by dividing a liquid crystal injection region by sealing materials in correspondence to the characteristics of color filters and injecting respectively different liquid crystals into the divided blocks. CONSTITUTION:A glass substrate 1 formed with thin-film transistors arranged in a matrix form to form pixels and oriented films 7 on pixel electrodes 6 and a glass substrate 2 laminated with three colors of color filters R, G, B disposed in correspondence to these pixel electrodes 6, a common electrode 11 and oriented films 12 are disposed to face each other via spacers and the liquid crystals are sealed into the spacing therebetween. Polarizing plates 3, 4 are arranged on the outer side of the substrates 1, 2. The liquid crystal injection region is bisected to, for example, regions R, G and region B or region R, B and region G by using the partition walls 14 consisting of a sealing material in correspondence to the characteristics of three colors of the color filters in such a manner that the transmission spectra of the color filters are not mixed. The respectively different liquid crystals are injected into the divided blocks and the substrates are sealed.

Description

Detailed Description of the Invention

[0001]

The present invention expands the production margin,
Further, the present invention relates to the configuration of a color liquid crystal display device having improved transmission efficiency of incident light.

Color liquid crystal display elements are thin and lightweight,
In addition, it has become a display device indispensable for portable personal computers and word processors by taking advantage of its low power consumption, and is used by replacing CCRT (color cathode ray tube) in a wide range of fields that require color displays. There is.

[0003]

2. Description of the Related Art Liquid crystal display elements are classified into active matrix type and simple matrix type, which are used differently depending on the application. However, the structure of an active matrix type liquid crystal display element suitable for large area display is described below. To explain, a drain bus line is patterned on a transparent insulating substrate such as borosilicate glass using a material such as aluminum (Al), chrome (Cr), and tantalum (Ta), and then indium oxide (In ₂ O ₃ ) and a tin oxide (SnO ₂ ) solid solution (commonly known as ITO) are formed as a film, and then a transparent conductive film at a thin film transistor (abbreviated as TFT) formation position is opened and a drain is formed at this position. A drain electrode connected to the bus line and a source electrode that works as a pixel electrode are provided, and the gate electrode is connected to the gate bus line. The connection with the TFT thin film forming technique and photolithography technique is formed by using (photolithography). Here, the source electrode is patterned over the entire area of the pixel formation position and also serves as the pixel electrode.

ITO is formed on the first substrate on which a large number of pixels and TFTs are thus patterned and the color filter.
A second insulating transparent substrate provided with a common electrode made of
After an alignment film is formed on each of the first substrate and the second substrate to perform the alignment treatment, the first substrate and the second substrate are opposed to each other with a minute gap of several μm, and the twisted nematic liquid crystal is placed in this gap. A color liquid crystal display element is completed by enclosing a liquid crystal such as (abbreviated as TN liquid crystal) and arranging a polarizing plate outside the first substrate and the second substrate.

FIG. 5 shows a sectional structure of a normally black color liquid crystal display device mainly including color filters. Here, the first glass substrate 1 and the second glass substrate 1
The two polarizing plates 3 and 4 arranged on the outer side of the glass substrate 2 are arranged in parallel with each other, and the liquid crystal layer 5 has TN.
Since liquid crystal is used, the display is dark (black) when not lit.

[0006] Here, IT is provided on the first glass substrate 1.
A pixel electrode 6 made of O is provided, and a rubbing-treated alignment film 7 is formed on the pixel electrode 6. Meanwhile, the second
A narrow (eg, 40 μm) black matrix 9 that borders the three color pixels forming a color filter is kept on the glass substrate 2 at a constant interval (eg, 70 μm) by using a metal film such as chrome (Cr). Pattern is formed, and in the meantime, red (hereinafter R), green (hereinafter G), and blue (hereinafter B) color filters are patterned by a printing method or a photo-etching method. There is a common electrode 11 and the alignment film 12 is further provided thereon.

In the color liquid crystal display device having such a structure, it is necessary that no light is emitted from the R, G, and B pixel regions of the color filter in the non-lighted state. However, the liquid crystal has wavelength dependency, and there is a problem that the light transmittance differs depending on the cell thickness of the liquid crystal.

FIG. 6 shows an example of liquid crystal cell thickness and R, G,
This shows the relationship with the transmittance of B light. In this case, if the thickness of the liquid crystal layer is kept at 5.9 μm in the R pixel portion, the transmittance of R light is 0 and the dark state can be maintained. In the G pixel portion, the dark state can be maintained by maintaining the thickness of the liquid crystal layer at 5.0 μm.

Therefore, as shown in FIG. 5, the thickness of each of the R, G, and B color filters is changed or the thickness of the color filters is made constant, and the thickness of the transparent resist (transparent film) provided thereon is set. By changing the height, the thickness of the liquid crystal layer corresponding to the R, G, B pixels is changed.

However, in this case, the spacers in the liquid crystal layer, which hold the first substrate and the second substrate at a constant interval, are concentrated in the R pixel region having the largest interval and the contrast is increased. There is a problem that it lowers.

Even if the thickness of the liquid crystal cell can be adjusted accurately, it is difficult to reduce the transmittance to 0 because the transmission spectrum of the color filter is not sharp as shown in FIG. . For example, for light with a wavelength near 500 nm, the transmittances are both close to 30%,
There is a problem that the G wavelength leaks from the B pixel.

[0012]

As described above, in a normally black color display device, the transmittance of light passing through the liquid crystal layer has wavelength dependence, and therefore Δn is Refractive index anisotropy, d is the thickness of the liquid crystal layer, λ
Is the wavelength of the light, the value of Δnd / λ is adjusted so that the transmittance becomes zero. Specifically, it is made by changing the value of d for each of the R, G, and B color filters, but it is difficult to accurately control the thickness of the liquid crystal layer.
Each of the color filters also has a problem in that the transmission spectrum is not sharp and the spacer pieces are generated, which causes a reduction in contrast and coloring. Therefore, this solution is an issue.

[0013]

According to the characteristics of the color filters of the three colors, the liquid crystal enclosing region is divided into two parts by a sealant, and different liquid crystals are injected into the two divided parts. When a guest-host type liquid crystal is used in a pixel area in which the liquid crystal enclosure area is divided into two and another liquid crystal is enclosed, a color liquid crystal display element is configured by not including a color filter in the pixel area. Can be resolved.

[0014]

FIG. 1 shows the structure of a liquid crystal display device according to the present invention. The conventional liquid crystal layer is formed of a single liquid crystal.
When the normally black method is adopted by changing the layer thickness of the liquid crystal by changing the thickness of each of the R, G, and B color filters, the light transmittance is set to 0.
In the display device according to the present invention, the liquid crystal injection region is divided into two by using partition walls 14 made of a sealing material so that the transmission spectra of the color filters are not mixed into R, G regions and B regions or R, B regions and G regions. Then, different liquid crystals are injected into these two divided sections to seal them.

By doing so, the thickness of the liquid crystal layer is adjusted to the optimum value by changing the thickness of the color filter for each of the R, G, and B pixels, whereas the common liquid crystal is used. It is only necessary to change the thickness of the color filter for the pixel portion where is used, which simplifies the process, and another liquid crystal can use a liquid crystal with completely different cell thickness dependence of the transmittance, which results in color mixing. It can be lost.

A transparent resist is used as a sealing material for dividing the liquid crystal injection area. When a light scattering material such as glass powder is mixed and used in this material, it is projected onto a black matrix and absorbed or reflected. It is very efficient because it can guide light to the color filters.

When a guest-host type (abbreviated as GH) liquid crystal is used as another liquid crystal, since the liquid crystal is originally colored, the color filter can be omitted only for that pixel as shown in FIG. .

[0018]

【Example】

Example 1 (related to claim 1, FIG. 2 and FIG. 3) As the second glass substrate 2, a product name 7059 manufactured by Corning Incorporated is used, and R is a product name CR-2000, G is a constituent material of the color filter. The product name CG-2000, B is a product name CB-2000, which uses a colored resin made by Fuji Hunt.
A color filter was formed with a thickness of μm. Next, when the product name ZLI-4792 (made by Merck Japan) is used as the liquid crystal, the film thickness at which the transmittance is 0 is R is 5.9 μm, G
Is 5.0 μm and the difference is 0.9 μm, so a transparent film (product name C
T, made by Fuji Hunt) 15 was formed.

Next, a transparent electrode 11 made of ITO and an alignment film 12 are formed on the same as in the conventional case, and the alignment treatment by rubbing is completed, and then a spinner is used over the entire area of the substrate 2. A transparent resist (product name CT, made by Fuji Hunt) was applied to a thickness of 6 μm in consideration of the required liquid crystal layer thickness of 5.9 μm at the R pixel position, dried at room temperature and stopped in a semi-cured state. Width as shown in Figure 3 using the etching technique
The R, G, and B pixel regions are separated into a B region and an RG region by a partition wall 14 of 35 μm.

An injection port 17 for injecting liquid crystal into the RG region
The injection port 16 for injecting the liquid crystal into the region B and B was formed with a width of 70 μm. Then, the TFT and the first glass substrate 1 on which the pixel electrode is formed are accurately aligned and bonded to each other, and heated at 200 ° C. to perform post-cure to form the partition wall 14 to form the partition wall 14. Was cured to bring the two substrates into close contact with each other.

Next, as a method of injecting liquid crystal, TN liquid crystal (product name ZLI-4792, manufactured by Merck Japan) is injected from the injection port 17 in the same manner as in the prior art in the steps of vacuuming the empty cell → immersing the empty cell liquid crystal container → depressurizing. And sealed. Next, as the liquid crystal to be injected from the injection port 16, the refractive index anisotropy Δn of the above TN liquid crystal is 0.094.
Therefore, it is desirable to set Δn d / λ of each color to the same value, and select a liquid crystal with Δn of 0.132 (0.094 × 5.9 ÷ 4.2), and inject in the same process to seal the color liquid crystal. The display element is completed. Example 2 (Claims 3, FIG. 4) FIG. 4 is a cross-sectional structure of an example. The difference from the structure of FIG. 2 is that a partition 14 made of a sealing material is used to form R, G and B regions. In the case of dividing into two, when the GH liquid crystal is used in the B region where a single liquid crystal is used, it is not necessary to provide a color filter, so that the manufacturing process can be reduced by that much.

[0022]

By implementing the present invention, it is possible to easily manufacture a color liquid crystal display device, and it is possible to solve problems of a color filter such as coloring and deterioration of contrast.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display element according to the present invention.

FIG. 2 is a partial cross-sectional view of another liquid crystal display element according to the present invention.

FIG. 3 is a plan view showing a partition pattern of FIGS. 1 and 2.

FIG. 4 is a partial cross-sectional view of still another liquid crystal display element according to the present invention.

FIG. 5 is a partial cross-sectional view of a conventional liquid crystal display element.

FIG. 6 is a relationship diagram between cell thickness of liquid crystal and transmittance.

FIG. 7 is a transmission spectrum of a color filter.

[Explanation of symbols]

 1 First Glass Substrate 2 Second Glass Substrate 5 Liquid Crystal Layer 7, 12 Alignment Film 9 Black Matrix 11 Common Electrode 14 Partition 15 Transparent Film

Claims (3)

[Claims] 1. A first glass substrate (1) having an alignment film (7) formed on thin film transistors and pixel electrodes (6) arranged in a matrix to form pixels, and the pixel electrodes (6). ) Corresponding to three color filters (R, G, B), the common electrode (11), and the alignment film (1).
The second glass substrate (2) formed by stacking 2) and 2) are made to face each other through a spacer, and the glass substrates (1), (2)
Liquid crystal is sealed in the gap between the substrates (1), (2)
In a liquid crystal display device in which polarizing plates (3) and (4) are arranged outside the liquid crystal display device, a liquid crystal encapsulation region corresponding to the characteristics of the three color filters is provided with a common liquid crystal by a partition wall (14) made of a sealing material. A color liquid crystal display device, characterized in that it is divided into a pixel region for enclosing the liquid crystal and a pixel region for enclosing another liquid crystal, and different liquid crystals are injected into the divided regions. 2. The color liquid crystal display device according to claim 1, wherein a light scattering material is added to a partition wall (14) made of a sealing material for partitioning the liquid crystal enclosing area. 3. A color filter is not provided in a pixel area in which a liquid crystal sealing area is divided into two and another liquid crystal is sealed,
The color liquid crystal display device according to claim 1, wherein a host type liquid crystal is used.