JPS6126668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a structure for preventing glare from transparent electrodes of a liquid crystal display panel.

[Conventional technology]

The electrode pattern of a liquid crystal display panel is normally transparent, and segments to which driving voltage is not supplied are not visible, but depending on conditions such as the refractive index and thickness of the material, they may become visible, reducing display quality. Sometimes I let it happen. Regarding this, Tokukai Akira
As disclosed in Japanese Patent No. 54-143246, it is considered that a film of metal oxide, silicon nitride, calcium fluoride, etc. with a predetermined refractive index and a predetermined thickness may be formed between the substrate and the electrode. ing.

In addition, regarding prevention of elution of alkali metals, etc.,
It is disclosed in JP-A-52-40152 and JP-A-51-14038.

Since liquid crystals are degraded by light rays, Japanese Patent Application Laid-Open No. 82443/1983 discloses the formation of a light ray filter, particularly ultraviolet rays, on a substrate.

[Problem that the invention seeks to solve]

The conventional technology disclosed in JP-A-54-143246 discloses only the prevention of glare in the electrode pattern, and the anti-glare coating is further utilized to prevent alkali metal elution from glass. There is no mention of technology that also serves as prevention, and the technology is still incomplete.

JP-A-52-40152 discloses only the prevention of electrode elution and alignment deterioration, but does not disclose at all the prevention of glare due to reflection of the electrode pattern. The same applies to JP-A-51-14038.

JP-A-52-82443 discloses a filter that prevents the influence of ultraviolet rays on a liquid crystal composition, but does not disclose how to prevent glare caused by reflection of an electrode pattern.

The present invention aims to comprehensively solve the above-mentioned problems, and aims to provide a coating that has both the effects of preventing the conspicuousness of the transparent conductive film of a liquid crystal display panel and preventing the elution of alkali metals. This is the purpose.

[Means for solving problems]

The liquid crystal display panel of the present application is a liquid crystal panel in which a liquid crystal composition is sandwiched between two substrates, and when soda glass is used as the substrate, a mixture of SiO ₂ and TiO ₂ is deposited on the substrate as the main component. ,moreover
The refractive index of the film doped with P ₂ O ₅ is
1.75 to 1.85 and a film thickness of 700 Å to 1200 Å.

〔Example〕

FIG. 1 shows one embodiment of the liquid crystal display panel of the present invention.

Here, transparent electrodes 2, 2' are formed on the soda glass substrates 1, 1', and insulating transparent coatings 6, 6' are formed on the transparent electrodes 2, 2'.

Furthermore, alignment films 3, 3' are provided on the insulating transparent film.
is formed, and a liquid crystal 5 is sealed between the alignment films 3 and 3'. Further, the thickness of the liquid crystal display panel is defined by the spacers 4 and 4'.

The liquid crystal panel of FIG. 2 shows another embodiment of the invention. In this embodiment, an insulating transparent coating 6,
6' is formed between the glass substrates 1, 1' and the transparent electrodes 2, 2'.

FIG. 3 shows the average surface reflectance of light when the thickness of the insulating transparent coatings 6, 6' is varied.
In this case, the refractive index of the liquid crystal is n=1.50. In this figure, ,, is an insulating transparent coating 6,
This is the average surface reflectance from the insulating transparent coatings 6 and 6' when 6' is changed to n=1.70, 1.75, and 1.82.

, , are the average surface reflectances from the transparent electrodes 2, 2' in the structure of FIG. ，
The thickness of the transparent electrodes 2 and 2' is 30 nm,
is the case where both thicknesses are 50 nm, and further,
In , the refractive indexes of the insulating coatings 6 and 6' on the transparent electrodes 2 and 2' are n=1.70 and 1.75, respectively, and in , the refractive indexes mentioned above are n=1.75 and 1.82, respectively.

Here, when the reflectance from the transparent electrode and the reflectance from the insulating transparent coating are approximately equal, conspicuousness and glare of the transparent electrode can be prevented.

FIGS. 4a and 4b show the difference between the reflectance from the transparent electrodes 2, 2' and the reflectance from the insulating transparent coatings 6, 6' with respect to changes in the thickness of the insulating transparent coating. Here, the refractive index of the absolutely transparent film is n=
1.70, 1.75, 1.80, 1.82 The refractive index of the transparent electrode is n=
2.2. The relationship between the difference in reflectance and the thickness of the insulating transparent coating is shown when the thickness is d=30 nm, 40 nm, and 50 nm. As mentioned above, the smaller the difference in reflectance, the less conspicuousness and glare of the transparent electrode, so from this figure, the refractive index of the insulating transparent coating n=
1.80, it can be seen that each condition of this thickness of 85 nm is optimal.

Next, in this embodiment, as the material for the insulating transparent coatings 6, 6' whose refractive index can be adjusted,
First, TiO ₂ and SiO ₂ were mainly selected, and P ₂ O ₅ was further added as an additive in an amount of about 0.005 to 5%. here
By adding P ₂ O ₅ , there is no need to take the trouble to form an alkali metal leaching film from soda glass.

An example of this manufacturing method will be described below.

Silicon alcoholate: Si( _OC4H9 ) ₄ and titanium alcoholate: Ti _{( OC4H9} ) _{4 in} ethanol:
Dissolve 10% in a solvent of methyl acetate (=1:2),
When 0.5% of H ₂ SO ₄ was added and further 0.02% of P ₂ O ₅ was added, the glass substrate was immersed and pulled up at constant speed, and baked at 500°C for 1 hour to form a mixed coating of SiO ₂ and TiO ₂ . n
=1.80, d=90 [nm]. This is the insulating transparent coating 6, 6' shown in FIG.

Next, apply Nesa to the above board by CVD etc.
[nm] was coated and patterned by etching to form transparent electrodes to produce a liquid crystal display panel. The liquid crystal refractive index at this time is 1.5. In this way, a panel was obtained in which the conspicuousness of the transparent electrode was completely eliminated. In addition, reliability tests showed that panels with a lifespan equal to or longer than conventional panels were obtained, and that this treated film prevented the elution of alkali metals from soda glass.
Therefore, the substrate subjected to this treatment does not need to be previously treated to prevent alkali elution, and the manufacturing process is not burdened compared to when conventional soda glass is used.

〔effect〕

As described above, the present invention provides a liquid crystal display panel in which a liquid crystal is sealed within a pair of soda glass substrates, and a transparent electrode is formed on the soda glass substrates. A transparent insulating film is formed, and the transparent insulating film is mainly composed of a mixture of SiO ₂ and TiO ₂ .
The refractive index of the coating is 1.75 to 1.75 with P ₂ O ₅ added.
1.85 and the film thickness is 700 Å to 1200 Å, it is possible to prevent the conspicuousness of the transparent conductive film on the substrate to the extent that it is almost indistinguishable.
Adsorption of P ₂ O ₅ prevents the elution of alkali metals from soda glass, improves the visibility of the LCD panel display, and improves reliability and durability. This improved mass production.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of one embodiment of the invention. FIG. 2 shows a cross-sectional view of another embodiment of the invention. FIG. 3 shows a relationship diagram between the thickness of the transparent insulating film and the surface reflectance. FIGS. 4a and 4b are diagrams showing the relationship between the thickness of the transparent insulating film and the difference in surface reflectance. 1, 1'...Substrate, 2, 2'...Transparent electrode, 5...
...Liquid layer, 6,6'...Transparent insulating film.

Claims (1)

[Claims] 1. In a liquid crystal display panel in which a liquid crystal is sealed within a pair of soda glass substrates and a transparent electrode is formed on the soda glass substrates, a transparent insulating coating is formed on the soda glass substrate or the transparent electrode substrate. The transparent insulating film consists of SiO ₂ and TiO ₂
What is claimed is: 1. A liquid crystal display panel characterized in that the film contains a mixture of the following as a main component and P ₂ O ₅ is added, the film having a refractive index of 1.75 to 1.85 and a thickness of 700 Å to 1200 Å.