JPH01188830A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To interrupt a light at a short wave length side, to prevent the deterioration of a color filter and to always obtain a high quality picture by providing a special ultraviolet cut filter at the light irradiation side of the color filter. CONSTITUTION:A matrix wiring and a thin film transistor composed of a scanning line group and a signal line group are formed at a first substrate 1a and a color filter 7 is arranged corresponding to respective picture elements 8 on a second substrate 1b. At the light incident side of the color filter 7, an ultraviolet ray cut filter 13 having a characteristic that the light transmittance of 350nm is 10% or below and the light transmittance of 420nm is 80% or above is provided. Thus, by protecting the color filter 7 with a material to suppress the light transmittance at the short wave length side, the deterioration of the color filter 7 can be prevented. Thus, a high quality picture is obtained for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a liquid crystal display device using liquid crystal, which is an electrical/light modulating substance.

(Prior Art) Conventionally, various driving methods have been considered for liquid crystal display devices using liquid crystal as an electrical/light modulating substance, such as static driving and multiplex driving. Liquid crystal display devices have also come to be used for constantly changing screens such as television screens. For this reason, liquid crystal display devices are required to have high quality and high resolution.

In order to meet these demands, active matrix type liquid crystal display devices were devised, and for example,
It is widely known and disclosed in Japanese Patent Application Laid-Open No. 56-25777 and others.

Regarding this type of liquid crystal display device, for example, a color liquid crystal display device using a thin film transistor (hereinafter abbreviated as TPT) will be described.

Usually, a TPT is provided at each intersection of matrix wiring consisting of a signal line group and a scanning line group on the same substrate, and one of the source electrode or drain electrode of the TPT is connected to the pixel electrode. For example, red (R) and green (G) are placed between this pixel electrode and the substrate.

A positive (B) color filter is provided. Further, a counter electrode facing the pixel electrode is formed on the other substrate, and a liquid crystal is sandwiched between this substrate and the above-mentioned substrate. Roughly speaking, polarizing plates are provided on both outer sides of the two substrates.

In this way, a liquid crystal display device having a liquid crystal portion, that is, a pixel, which is sandwiched between two electrodes and reacts by applying a voltage to the electrodes, was formed.

By providing TPT on each pixel electrode, it is possible to improve the ability to activate the pixel you want to activate without affecting neighboring pixels and maintain that state, resulting in high-quality images. be able to.

(Problems to be Solved by the Invention) As described above, various driving methods have been devised to obtain high-quality images. However, no consideration was given to the deterioration of image quality due to deterioration of color filters.

However, the deterioration in image quality caused by the deterioration of the color filter significantly reduces contrast.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal display device that can provide high-quality images over a long period of time by preventing deterioration of color filters.

Structure of the Invention (Means for Solving the Problems) The present invention provides a liquid crystal display device having a plurality of pixels and a plurality of color filters corresponding to each pixel. Equipped with an ultraviolet cut filter that has a light transmittance of 10% or less and a 420nm light transmittance of 80% or more! ＝Characterized by:

(Function) First: In order to investigate the cause of the deterioration of the color filter as described above, the following experiment was conducted. A glass substrate with a green color filter dyed using CFGll (Japanese Herbal Medicine Co., Ltd.), which is a green dye, was installed using a high-pressure mercury lamp (15mW).
/cm2) was left under irradiation.

FIG. 4 shows the deterioration of the color filter under irradiation with a high-pressure mercury lamp (15111 W/Cm2). The solid line a shows the characteristics of the color filter before irradiation, the dotted line shows the characteristics of the color filter after 10 minutes of irradiation, and the - dotted line C shows the characteristics of the color filter before irradiation.
It shows the characteristics of the color filter after 0 minutes of irradiation.

As can be seen from this figure, if left for 40 minutes, the edge color filter has deteriorated to such an extent that its characteristics are lost.

This shows that color filters are degraded by light with shorter wavelengths, that is, by ultraviolet rays.

Therefore, if the color filter is protected with a material that suppresses the transmittance of light on the short wavelength side, deterioration of the color filter can be prevented.

And I tried the following experiment. In this experiment, a color filter 59 similar to the above experiment was placed on a glass substrate, a glass exhibiting short-wavelength light blocking characteristics was placed on top of the filter, and the filter was irradiated with a high-pressure mercury lamp ('l 5 mw/cm2). O minutes, 4
I left it for 0 minutes and checked the deterioration status of the color filter.

The short wavelength light blocking glass used here is UV35°UV3
7. L-42, and the short wavelength light blocking characteristics of each are shown in FIG.

Curve a shows the UV35 short wavelength light blocking characteristic, which is 3
This suppresses short wavelengths of 20nllll or less.

The curve shows the short wavelength light blocking characteristic of UV37, which is Q
This suppresses the short wavelength of 40 nm.

Curve C shows the short wavelength light blocking characteristics of L-42 4QQnl
This suppresses short wavelengths of 11 or less.

Therefore, Figure 6 is a diagram showing the deterioration of the color filter due to irradiation with a high-pressure mercury lamp (15 mW/Cm2) when the color filter is protected using UV35, and the solid line a shows the characteristics of the color filter before irradiation. , the dotted line C indicates the characteristics of the color filter after irradiation for 10 minutes, and the dashed-dotted line C indicates the characteristics of the color filter after irradiation for 40 minutes.

Similarly, Figure 7 shows the deterioration of the color filter due to irradiation with a high-pressure mercury lamp (15mW/Cm2) when the color filter is protected using UV37, and Figure 8 shows the color filter when it is protected using L-42. ing.

Looking at these figures 6, 7, and 8, the following can be seen. Even if UV35 is used, the deterioration of the color filter cannot be suppressed, but if UV37 is used, the deterioration of the color filter can be suppressed. If L-42 is used, deterioration of the color filter can be sufficiently suppressed.

This can be prevented from deterioration by protecting the color filter with a material that suppresses short wavelength light of 400 nm or less, as shown in the UV37 (?) or L-42 characteristics shown in Figure 5. .

Figure 9 shows the light transmittance characteristics of each color filter of red (R), blue (B), and green (G), and curve a is positive (
B) Two curves show the characteristics of green (G) and one curve C shows the characteristics of red (R).

As you will see, if you block all ultraviolet rays below 400 nm, you can prevent the color filter from deteriorating, but blue (B)
This impedes the characteristics of the color filter and deteriorates the color reproducibility of the color display device.

For this reason, 35 is a material that blocks ultraviolet rays.
It is preferable to use a material in which the light transmittance of 01m is 10% or less and the light transmittance of 42Orim is 80% or more.

By doing so, it is possible to prevent deterioration of each color filter without impairing the characteristics of the blue (B) color filter.

(First Embodiment) Next, a first embodiment of the present invention will be described with reference to FIG.

A matrix wiring (not shown) consisting of a scanning line group and a signal line group and a TPT (not shown) are formed on the first substrate 1a.

Then, it is connected to the island-shaped image charger 9 in the matrix wiring.

Further, on the second substrate 1b, 7-j of the first substrate 1a
: The light-shielding film 11 is formed so as to cover the portion where voltage is applied to the T, matrix wiring and liquid crystal, that is, the periphery of the pixel 8.

Further, a color filter 7 is installed on the second substrate 1b corresponding to each pixel 8, and the filter 1 is connected to the ultraviolet light filter 1.
3 is placed on the illumination side of the color filter 7, and a counter electrode 18 is further formed.

The structure is such that the liquid crystal 15 is sandwiched between these two substrates and the polarizing plates 3a and 3b are installed on the outer surface of the cylinder.

Next, the second substrate 1b of the display device (3) having the configuration 7:i'
The manufacturing method will be explained with reference to FIG.

First, a synthetic dyeing base material is coated onto the light-transmitting second blocking plate 1b using a spinner or a roll coater to a film thickness of about 1°0ρ.

Here, various synthetic dyeing base materials suitable for black dyeing can be considered, but in particular, R633L1 (manufactured by Nippon Koyaku Co., Ltd.) or J
As a result of research, it was found that DS-509 (manufactured by Japan Synthetic Rubber Co., Ltd.) is good. Here, an example using JDS-509 (manufactured by Japan Synthetic Rubber Co., Ltd.) is shown.

Then, prebaking was performed for 30 minutes at 140'c for the above-mentioned synthetic dyeing base material 4.

Next, exposure is performed using a mask, and the synthetic dyed substrate is irradiated with ultraviolet rays to form latent images at predetermined intervals through a crosslinking reaction. (A in the figure) Then, development is performed to form a predetermined opening, and the temperature is 30°C at 180°C.
After boiling for a minute, immerse it in a black dyeing tank for dyeing, then add tannic acid and tartarite to a 1% solution each at 50'C for 2 hours.
The light shielding film 11 is formed by partial dipping and fixing treatment.

(B in the figure) The dyes and dyeing conditions used at this time are shown in Table 1.

Roughly place the ultraviolet cut filter 13 on top of it.
, m in film thickness. (C in the figure) For example, it is easy to manufacture if a resin such as JMC (manufactured by Japan Synthetic Rubber Co., Ltd.) or JMT (manufactured by Japan Synthetic Rubber Co., Ltd.) is used as the ultraviolet cut filter 13; has a light transmittance of 10% at 385 nm and 50% at 400 nm, making it very suitable for ultraviolet cut filters.

Next, a photosensitive dyeing base material suitable for color dyeing, such as 863
3L1 (manufactured by Nippon Koyaku Co., Ltd.) is applied to the entire surface and irradiated with ultraviolet rays using an exposure mask to obtain latent images at predetermined intervals. (
(D in the figure) Then, it is developed and immersed in a green dyeing bath to form a green (G) color filter 7 (E) in the figure, followed by a fixing process similar to that described above. The dyes and dyeing conditions used at this time are shown in Table 1.

Repeat this process two more times for red (R), green (G), and blue (
The color filter 7 of B) is completed. (F in the figure) The second substrate 1b thus formed and the first substrate 1a to which matrix wiring, pixel electrodes 9, and TPT are connected are accurately aligned, and the side substrates are pasted. Combined U
A liquid crystal display device is obtained by injecting liquid crystal 15 and sealing.

In the liquid crystal display device of this embodiment, by providing the ultraviolet cut filter 13 on the light irradiation side of the color filter 7, deterioration of the color filter 7 can be suppressed.

In addition, since this ultraviolet cut filter 13 is made of resin, it can be installed easily and inexpensively, and also serves as a smoothing layer, so that when dyeing the color filter 7, the smoothness of the color filter 7 is reduced by 1q. The color filter 7 can be dyed uniformly and evenly. Therefore, it has become possible to provide a liquid crystal display device that can provide higher quality images.

Table 1 (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 10. Components similar to those in the first embodiment are designated by the same reference numerals.

A matrix wiring is formed on the first substrate 1a by a group of scanning lines and a group of signal lines, and an island-shaped ultraviolet cut filter is formed in each of the lines 71 to 1. Roughly, the top of each is red (R).

? ! '(G) and blue (B) color fills 7, and a pixel electrode 9 is provided roughly above them. The pixel electrode 9 and the matrix wiring are connected by TPT. Further, five light-shielding films are placed so as to extend over nine spaces to each pixel electrode (9) and over the periphery of each pixel electrode (9).

A second substrate 1 is placed on the side opposite to such a first substrate 1a.
b is installed, and a counter electrode 18 is provided on the first substrate 1a side.
is installed.

A liquid crystal 15 is sandwiched between the first substrate 1a and the second substrate 1b.

By configuring the liquid crystal display device as described above, high quality images can always be obtained by preventing deterioration of the color filters as in the first embodiment.

Furthermore, by disposing the light shielding film 11, pixel electrode 9, and color filter 7 on the same substrate, alignment between the first substrate 1a and the second substrate 1b is no longer necessary, resulting in a more productive and inexpensive display. The device can be manufactured.

Although the present invention has been described in detail above, it goes without saying that the present invention can be used with MIM elements and the like in addition to TPT as nonlinear elements.

In addition to the active matrix type, it can also be used for simple matrix type liquid crystal display devices.

[Effects of the Invention] As described above, by providing an ultraviolet cut filter on the light irradiation side of the color filter, deterioration of the color filter can be prevented by blocking light on the short wavelength side that causes deterioration of the color filter. A liquid crystal display device that can always provide high-quality images can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front view of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 2 is a front view of the liquid crystal display device according to a first embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view taken along the line, and FIG.
Figures 1 and 5 are diagrams showing the transmittance of each UV absorbing material axis, and Figures 6, 7, and 8 are color filters when each UV absorbing material is used. FIG. 9 is a diagram showing the transmittance of a color filter, and FIG. 10 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention. ′! a......First board'! b...
......Second substrate 3a, 3b...Polarizing plate 5...Signal line 7...
・・・・・・・・・Color filter 8・・・・・・・・・
・・・・・・Pixel 9・・・・・・・・・・・・・・・
・Lateral electrode 11・・・・・・・・・・Light shielding film

Claims (1)

[Claims] In a liquid crystal display device having a plurality of pixels and a color filter corresponding to each pixel, a light transmittance of 420 nm at 350 nm is 10% or less on the light incident side of the color filter.
1. A liquid crystal display device comprising an ultraviolet cut filter having a light transmittance of 80% or more in nm wavelength.