JPS5848098B2 - Method for manufacturing color matrix liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a color matrix display device.

Monochrome matrix display devices have been well known in the past.

For example, in a liquid crystal cell in which a liquid crystal material is sandwiched between two upper and lower substrates, as shown in FIGS. A plurality of striped electrodes (hereinafter referred to as X electrodes) are provided,
On the inner surface of the lower substrate in contact with the liquid crystal material, a plurality of striped electrodes (hereinafter referred to as Y electrodes) are provided in vertical lines, and the X and Y electrodes are arranged perpendicularly to each other. This structure results in a monochrome liquid crystal matrix display device.

Now, when each of these electrodes is selected appropriately and a predetermined alternating current voltage is applied, the light passing through the intersection of the electrodes becomes bright or dark depending on the selection method, or scatters, and various shapes are obtained. It is known as a liquid crystal matrix display device.

Now, as a technique for colorizing such a monochrome liquid crystal matrix display device, a technique using a color filter is publicly known (for example, disclosed in Japanese Utility Model Application Publication No. 51-93676).
Publication No.).

In this case, a filter (hereinafter referred to as a color filter) having a stripe-shaped colored portion that is regularly and repeatedly painted in the three primary colors of red, blue, and green is tightly placed in front of the liquid crystal matrix or display device. Just place it.

In this case, it is necessary to precisely match the geometric dimensions and position of the striped colored portion of the filter with the aforementioned striped X electrode or Y electrode.

By appropriately selectively driving each electrode of the liquid crystal matrix display device in synchronization with a color signal, a color matrix liquid crystal display device can be obtained based on the same principle as that of a cathode ray tube color television.

However, in the method using such a color filter, the colored surface of the filter and the electrode surface of the color matrix liquid crystal display device are separated.

Therefore, depending on the viewer's viewing angle (hereinafter referred to as viewing angle),
There was a drawback that the colored surface of the filter and the striped electrode surface of the liquid crystal display device were misaligned.

Furthermore, it is difficult to attach color filters to matrix display devices with high precision.

That is, since the width of the striped electrodes is at most 50 .mu.m and the interval between the electrodes is about 10 .mu.m, it is difficult to mount color filters thereon with high dimensional accuracy.

In order to improve the above-mentioned drawbacks, a method of repeatedly and regularly painting the surface of the striped electrode with the three primary colors can be considered.

One method for this is to form striped electrodes in advance, perform screen printing for each of the three primary colors, and repeat the printing three times in total.

However, this method has the disadvantage that printing misalignment occurs because the striped electrodes are fine.

There is also a method of coloring using photolithography,
The process was complicated because this process had to be repeated for each of the three primary colors.

The present invention relates to a novel method for manufacturing a color matrix display device that has been devised to overcome the drawbacks of conventional techniques, and more particularly to a method for periodically and regularly coloring striped electrodes in three primary colors.

That is, in a display device in which Ta is t[j, the inventor anodizes this Ta layer to form Ta 2 0 on Ta.
Conventional technology (for example, Japanese Patent Laid-Open No. 50-80798
The present invention focused on the method (see Japanese Patent Application Publication No. 2003-110000) and applied it to a method of manufacturing a color multiplex display device.

According to the present invention, first, a specific type of metal film is formed over the entire surface of the inner surface of the lower substrate that is in contact with the liquid crystal.

This metal film is etched into a stripe shape as shown in FIG. 2C to form a Y electrode.

Next, every second of the plurality of striped electrodes patterned in this manner is selected, each electrode is connected in common, and anodized in an anodizing bath for a predetermined period of time.

In this way, only the selected electrodes are colored in the desired color, for example red.

Next, every other unselected striped electrode is selected, each electrode is connected in common, and anodized for a predetermined period of time to be colored, for example, blue.

Finally, the remaining striped electrodes are commonly connected, anodized under predetermined conditions, and colored green.

According to the above, by repeating selective anodic oxidation of striped metal electrodes three times, fine patterns can be created without color shift due to screen printing and without complicated processes such as photolithography. Multicolored colored surfaces can be easily and inexpensively produced.

Hereinafter, a method for manufacturing a color matrix liquid crystal display device according to the present invention will be described in detail based on Examples.

First Step: Forming a Metal Film on the Lower Substrate A metal is formed by vapor deposition or sputtering on a transparent substrate such as glass or an opaque substrate such as ceramics having an insulating mirror surface.

Suitable metal electrodes include metals that are anodically oxidized to form a colored oxide film and whose color can be easily controlled, such as titanium, zircon, hafnium, vanadium, niobium, and copper. Niobium, zircon, and copper are suitable from the viewpoint of color clarity and corrosion resistance.

2nd step Formation of Y electrode on the lower substrate The method of forming the electrode on the insulating substrate is that the transparent electrode on the upper substrate is formed by a known method using tin oxide, indium oxide, etc. However, in the case of metal electrodes, after the entire surface is vapor-deposited on the substrate, the desired electrode width is covered with ink, resist, etc., and the exposed parts are etched using a chemical method or a method such as reverse sputtering, and then the coating is removed. After removing the film or masking the gap, the film may be deposited on the substrate by a method such as low-temperature sputtering or vapor deposition, and then the mask may be removed.

Third step: Periodically and regularly colored metal electrodes in the three primary colors of the Y electrodes are desirably colored by an anodic oxidation treatment on their surfaces.

The reason for this is that by keeping the anodic treatment conditions constant, a large number of strip electrodes can be colored in a uniform color at the same time.

As an example, if niobium is used as the metal electrode, first select every second Yi electrode, connect them in common, and
When the anode is anodically oxidized in a sulfuric acid solution using carbon as a Nio718 electrode, it is colored deep blue at 20V.

Next, the remaining Y electrodes are connected in common and anodized at 70V, resulting in a reddish-purple color.

The last remaining Y electrodes were connected in common and anodized at 90V, yielding a green film.

It is desirable for the electrode according to the present invention to be brightly colored, and from this point of view niobium is an excellent material.Although it has poorer corrosion resistance, it can be anodized at low voltage. As far as it is possible,
Copper is excellent.

In this way, fine and precise coloring can be achieved by simply selectively anodizing the electrode without causing any color shift on the surface of the Yi electrode.

Fourth Step Formation of X-electrode on Upper Substrate On the surface of the substrate 1, as shown in FIG. 2B, a large number of band-shaped transparent electrodes 4 are formed, together forming an X-electrode group.

Regarding the method of forming the electrode on the insulating substrate, the transparent electrode on the upper substrate is formed by a known method using tin oxide, indium oxide, or the like.

Fifth Step: Assembling the Liquid Crystal Cell As shown in FIG. 2a, a transparent substrate 1 and a transparent or opaque substrate 2 are placed facing each other at an interval of about 5 to 20 μm using a sealing material 3 which also serves as a spacer.

A liquid crystal material γ which electrically exhibits a phase transition phenomenon between cholesteric materials is sandwiched in the liquid crystal cell thus formed.

If the dot group made up of the XYi poles of the liquid crystal cell is driven by applying an appropriate voltage to make the liquid crystal cloudy, the cloudy liquid crystal will diffusely reflect the color of the underlying metal, so the underlying color will be clearly visible to the eye. However, since the underlying metal reflects light in a certain direction in the transparent area, it is not recognized as a clear color, so a display is performed.

As shown in Figure 1, a phase change type liquid crystal display generally has electro-optical characteristics when a voltage is applied, it changes from a transparent G state to an F state with low light transmittance, and then returns to a high voltage state with low light transmittance. This results in a high N state.

When the voltage is lowered, it does not follow the same path as when the voltage was increased, but takes various different relaxation processes depending on how the voltage is lowered.

For example, Merck's E-8 is used as a nematic liquid crystal, and BDH's CB is used as a chiral nematic liquid crystal.
-15, the phase transition voltage varies depending on the concentration of CB-15, but when 5.7% CB-15 is mixed,
It is possible to produce a liquid crystal display that exhibits a transparent fi N state when a voltage of about 9 V is applied, and becomes a cloudy F state when the voltage is rapidly lowered to about 3 volts.

In the present invention, a liquid crystal material exhibiting such properties is sandwiched between a transparent electrode and a mirror metal electrode whose surface is colored by anodizing, and when the liquid crystal is in a transparent state, light is reflected in a certain direction. Therefore, it is only perceived as a pale color by the eye, but if the liquid crystal becomes cloudy due to the electro-optic effect, the color of the underlying metal is diffusely reflected, and the color is perceived as a clear color.This is used to display images. It is.

The liquid crystal material to be sealed is a P-type nematic liquid crystal material mixed with a small amount of cholesteric liquid crystal or chiral nematic liquid crystal.

As a P-type liquid crystal material, Rotsch's TN101,2 is used.
In addition to E-7 and E-8 manufactured by Merck & Co., any material may be used as long as it is a P-type nematic fluid, but materials with a wide temperature range, low viscosity, and large Δε are preferable.

Further, as the cholesteric liquid crystal, a derivative of cholesterol can be used. Many compounds are known as the chiral nematic liquid crystal, but for example, CB-15 manufactured by BDH Chemicals gives good results.

As an example, Merck's E-7 is used as a nematic liquid crystal.
and added 5.5% of chiral nematic liquid crystal material 4-cyano-4'-(2-methylbutyl)biphenyl.
The liquid crystal material to which was added was held in a liquid crystal cell as shown in FIG. 2a.

The electrode gap was 10 μ, and a 3 2 1 {z square wave was used for driving.

When no voltage is applied, the liquid crystal layer shows the G state shown in Figure 1 and is transparent; however, when a voltage of 8V is applied, it shows the N state (nematic state) shown in Figure 1, which is transparent, but rapidly changes. By lowering the voltage to 3 V, the liquid crystal became in the F state (cholesteric state), and the liquid crystal became in a light scattering state, so that it diffusely reflected light according to the metal color of the base of the dot.

At this time, even when the voltage was slowly lowered from 8V to QV, a similar phenomenon was observed.

As described above, according to the present invention, it is possible to perform fine and precise coloring at low cost and efficiently by simply selectively anodizing the electrode without causing any color shift on the Yi electrode surface. can.

Further, in the color matrix display device manufactured according to the present invention, the surface of the electrodes that are in direct contact with the liquid crystal is a colored anodic oxide film.

This electrode surface constitutes a pixel.

Therefore, in the present display device, the pixels and the colored portions are integrated both in plan and in cross section, and no deviation in plan or gap in cross section occurs.

Therefore, firstly, it is possible to obtain a display without any color shift on the surface.

Second, because the pixels and colored parts are in close contact with each other in cross-section,
Even when the display surface is observed from various directions, problems such as misalignment between pixels and colored parts due to differences in viewing angle do not occur, and a display with extremely good viewing angle characteristics can be obtained.

Thirdly, since the inner surface of the lower substrate in contact with the liquid crystal serves as a reflective surface for incident light, there is no unnecessary reflection or absorption by the lower substrate, and a clear color display can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between applied voltage and light transmittance of a phase change liquid crystal display. FIG. 2a is a schematic diagram showing a cross section of the display device of the present invention;
Figures b and c are schematic plan views showing the configuration of 1 in Figure 2a.

Claims (1)

[Claims] 1. In a method for manufacturing a color matrix liquid crystal display device comprising an upper substrate having a plurality of strip-shaped X electrodes, a lower substrate having a plurality of strip-shaped Y electrodes, and a liquid crystal layer sandwiched between the two, the Y electrodes are After forming a metal film on the inner surface of the lower substrate in contact with the liquid crystal layer, it is formed by etching, and then Y electrodes are selected at predetermined intervals, connected in common, and anodized. , colored with one of the three primary colors, then selected the remaining Y electrodes at a predetermined interval, connected commonly and anodized, and colored with the other of the three primary colors. A method for manufacturing a color matrix liquid crystal display device, characterized in that the Y electrodes remaining at the end are connected in common and subjected to anodization treatment to be colored in the remaining color among the three primary colors.