JPS6212900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an electrode substrate for a liquid crystal display device using cholesteric-nematic phase transition.

Liquid crystal display devices (LCDs) have advantages such as low power consumption, low voltage drive, small size, and thinness, and have been put to practical use in wristwatches, calculator displays, etc.

As the next application field for LCDs, X-Y matrix type displays and color displays for various information processing terminals, measurement displays, etc. are thought to be promising, and various systems for X-Y matrix type LCDs have been reported so far. There is. Among these, liquid crystals having a memory effect (memory liquid crystals) are characterized in that they do not require refreshing and can be driven even with a large number of scanning lines. Furthermore, color display liquid crystals have the characteristic of being able to provide design properties and improve visibility.

Cholesteric-nematic phase transition (CNT) type liquid crystals are applied to two types: a type that has the characteristics of memory display and high-speed writing, and a guest-host type type in which a dichroic dye is added. Applicable to

A CNT type liquid crystal cell has a structure in which a P-type nematic-cholesteric mixed liquid crystal is sandwiched between vertically aligned transparent electrode substrates, and exhibits light transmission intensity-applied voltage characteristics as shown in FIG.
Figure 2 is an explanatory diagram of the principle of memory writing using the above characteristics, where figures a and c are applied voltage-time relationships, and figures b and d are light transmission intensities of the liquid crystal corresponding to figures a and c, respectively. - It is a diagram showing a time relationship.

To explain this using FIGS. 1 and 2, the memory display can be realized in two stable states obtained after removing the applied voltage shown in FIG. 1: a relatively transparent state (S) and an opaque state. This is done using the state (F ₀ ).

Figure 3a is an example of a partial cross-sectional view of a CNT liquid crystal display element that performs a conventional X-Y matrix display. 3 and 3' are liquid crystal vertical alignment layers provided on a glass substrate including the electrodes, and 4 is a CNT type liquid crystal. When driving an element with a fine pattern using such an X-Y matrix,
In the vicinity of the intersection of the X and Y electrodes 2 and 2', where a voltage higher than V _H is applied between the X and Y electrodes, an electric force line distribution as shown by arrow 5 in FIG. If such an electric force line distribution is shown as a voltage distribution in the cross section in the direction of the X electrode 2, it will be as shown in Figure 3b.
A region where sufficient voltage is applied to scatter light is created in the non-electrode portion near the intersection of the Y electrodes 2 and 2', as shown in Fig. 3c.
Light scattering occurs around the pixel as shown in
A part 6 in the F′ state appears, and this scattering part expands over time and becomes the F ₀ state at the time of fixation.
There was a drawback that scattering was memorized.

The present inventors utilized the property that the smaller the helical pitch of the liquid crystal in the thickness direction of the liquid crystal cell, the weaker the light scattering intensity and the memory effect.
and b are partial end views cut at a non-electrode portion and an electrode portion of the upper electrode substrate, respectively. ), insulating protrusions 7, 7' are provided on the non-electrode parts of the electrodes 2, 2' side of the substrates 1, 1', each having X and Y electrodes 2, 2' on their respective surfaces. Further, colored coatings 8, 8' are provided thereon, and vertically aligned liquid crystal layers 3,
The two electrode substrates 9 and 9' provided with
The electrodes 2 and 2' are arranged to face each other at right angles, and a CNT type liquid crystal is sandwiched between them to form a liquid crystal cell. The thickness of the liquid crystal between the colored film 8 or 8' on the part 7 or 7' and the electrode part of the other electrode substrate 9 or 9', that is, the Y electrode 2' or the X electrode 2, is The present invention was achieved by discovering that the above-mentioned drawbacks of the prior art can be eliminated by making the thickness of the liquid crystal thinner than the thickness of the liquid crystal between the intersections of ', and that the contrast can be improved by providing a colored film. It is. In this case, generally the non-electrode portion, that is,
The thickness of the liquid crystal in the colored coatings 8, 8' on the protrusions 7, 7' is set to be equal to or less than the number of pitches in which the spiral of the CNT type liquid crystal has a memory effect. In normal cases, it is desirable to keep the distance to about 3 pitches or less. Moreover, it is clear from the principle that the above-mentioned convex part has the above-mentioned effect even if it is formed partially overlapping the electrode part. Furthermore, the height of the convex portion is determined by taking into account the thickness of the liquid crystal cell, the driving voltage, the type of liquid crystal, the manufacturing method of the liquid crystal cell, etc.
The height is usually about 0.1 to 5μ.

Furthermore, when dichroic dye is added at a rate of 0.01 to 5% to a system that uses cholesteric phase liquid crystals larger than the pitch described above and does not have a memory function, the liquid crystal and dichroic dye become almost parallel to the electrode surface inside the cell. To become
It appears colored, but when voltage is applied, it disappears to stand vertically. Originally, in this system, since the background is colored, only negative display can be performed by erasing the color with electrodes, but by using the substrate of the present invention, it is possible to reduce the thickness of the liquid crystal in the non-electrode area to a thickness that does not form a spiral. Therefore, by changing the coloring of the background, a display with high color contrast can be achieved. The height of the convex portion is usually about 0.5 to 10μ, but this height is determined not only by the thickness of the liquid crystal layer but also by the thickness of the liquid crystal layer.
It is determined by taking into consideration the strength of the vertical alignment agent, the helical pitch of the liquid crystal, etc. Usually it is one-fifth to one-half of the cell thickness.

The present invention relates to a method for manufacturing a reflective electrode substrate when the liquid crystal display element as described above is a reflective type.

That is, in the present invention, a patterned non-transparent electrode layer formed on a transparent substrate is used as a mask, and a photosensitive resin film provided on this electrode layer is exposed and developed from the back side of the substrate, thereby removing the non-transparent substrate. The convex portion is formed of a photosensitive resin coating on the electrode portion and has a colored coating on the surface which is previously provided on the coating, and is provided with high precision and in a simple process.

The manufacturing process of a reflective electrode substrate for a reflective liquid crystal display device according to the present invention will be described below with reference to FIGS. 5a to 5c.

As shown in FIG. 5A, a non-transparent conductive layer 22 is formed on a transparent substrate 21 by a conventional method, and is patterned in accordance with a predetermined electrode pattern.

Then, as shown in Figure b, a non-transparent conductive layer 2 is formed.
A negative photosensitive resin film 23 having a predetermined thickness thicker than the electrode layer 22 is provided on the entire surface of the transparent substrate 21 including the electrode layer 22, and a colored film 24 is further provided thereon.
If the transparent substrate is exposed to light from the back side as shown by the arrow 25 and developed to remove the resin coating 23 and colored coating 24 on the electrode layer 22, the non-electrode portion of the substrate 21 will become photosensitive, as shown in FIG. A convex portion 23' made of resin and having a colored coating 24' on the surface is obtained.

As the transparent substrate used in the present invention, inorganic or organic materials with good transparency, such as glass, acrylic, polyester, and polycarbonate, are used.

In addition, non-transparent electrodes include Al, Cr, Sn,
Metals such as Fe, Zn, Au, Ag, Pd, Cu, Pb, Co, and Ni, conductive metal oxides, metal nitrides, and the like can be used.

In addition, as the negative photosensitive resin, ordinary negative photosensitive resins such as azide rubber type, cyclized rubber type, polyvinyl cinnamate type, cinnamylidene type, acryloyl type, unsaturated polyester type, and photosensitive silicone are used. .

In addition, as materials for the colored film, black pigments, colored pigments, metals, metal oxides, metal carbides, etc. are used, and these can be applied as they are or in the form of dispersed or dissolved in resin etc. by spin coating, dipping, roll coating, etc. Films are formed by coating methods, sputtering, vapor deposition, CVD, etc. Although the thickness of this coating varies depending on the material used, it is generally preferable that the thickness is about 0.01 to 10 μm.

Furthermore, in the present invention, in order to protect the electrodes and prevent substances harmful to the liquid crystal from leaching from the resin-containing base material, after forming the convex portions 23', a colored film 24' and SiO, _SiO2 , _MgF2 ,
A layer of inorganic insulating material such as Al ₂ O ₃ or LiO-Sio ₂ may also be provided.

After the above steps, a liquid crystal vertical alignment agent layer may be provided on the electrodes and the colored film or on the inorganic insulating layer. Examples of this vertical alignment agent include a silane coupling agent having an alkyl group, an organic chromium complex, silicon, etc., and the alignment agent layer is coated using normal coating methods such as flow coating, dipping, spin coating, and roll coating. provided by.

Embodiments of the present invention will be described in detail below with reference to FIGS. 5a to 5e.

Example 1 The chromium layer of a glass substrate 21 on which a metallic chromium layer was formed by vapor deposition was etched using a normal photoetching method to form a chromium electrode layer 22 corresponding to a predetermined parallel electrode pattern on the substrate 21 ( In Figure a), a cyclized rubber-based negative photosensitive resin layer 23 is formed to a thickness of 2 μm on the surface of the substrate 21 including the electrode layer 22 by a spin coating method, and then a layer of 1000 Å is further deposited on the resin layer by a vapor deposition method. A colored film 24 made of chromium is provided to a thickness of
By exposing to ultraviolet light of 100 W/m ² for 60 seconds and developing with xylene, a colored film 24' is formed on the non-electrode part of the substrate 21, and a transparent resin protrusion 23' with a height of 2 μm and a non-transparent electrode are formed. An electrode substrate having 22 electrodes was obtained (FIG. c).

On the other hand, the conductive layer of a glass substrate having a transparent conductive layer on its surface was processed by a conventional method into the same parallel electrode pattern as the electrode layer 22 of the electrode substrate described above, thereby producing an entirely transparent electrode substrate.

After providing a silicone-based liquid crystal vertical alignment agent layer on the entire surface of the electrode side of the electrode substrate with the non-transparent electrode and the electrode substrate with the transparent electrode by a dipping method, the electrodes of both substrates were perpendicular to each other with an inter-electrode spacing of 8μ. A liquid crystal cell was fabricated by arranging both substrates to face each other, and a P-type cholesteric liquid crystal with a pitch of 1.8 μm was sealed in the cell to fabricate a memory type liquid crystal display element. In this device, there was no clouding in the non-image areas, and a display with good color contrast was obtained due to the colored coating on the surface of the convex portions.

Example 2 A convex portion with a height of 4μ and a colored film were formed on the reflective substrate of Example 1, and a cell with a thickness of 10μ was manufactured in the same manner as in Example 1, and the liquid crystal was E-7.
(manufactured by BDH) with 5% of KCB15 (manufactured by BDH) and 1% of D3 (manufactured by BDH, dichroic dye) was sealed in the cell, and the back of the cell was sealed. By arranging a reflective plate in the display area, a guest-host type liquid crystal display element capable of positive type display with little coloration in the background of the display area was obtained.

According to the present invention, an electrode substrate for a liquid crystal display element with excellent characteristics can be manufactured with high precision through a simple process.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the light transmission intensity vs. applied voltage characteristics of a CNT type liquid crystal, Figure 2 is a diagram explaining the principle of memory writing in a CNT type liquid crystal cell, and Figure 3a is an X-Y matrix display memory element. , a diagram showing the distribution of electric lines of force near the intersection of the Y electrodes, Figure 3b is a diagram showing the voltage distribution between the two electrodes around the intersection of the X and Y electrodes, and Figure 3c is a diagram similar to Figure 3b. A diagram showing a focal conic region appearing near the intersection of the X and Y electrodes due to the voltage distribution between the X and Y electrodes. FIG. 4 shows an X-Y matrix display memory liquid crystal display element using the electrode substrate obtained by the present invention. FIG. 5 is a partial end view showing the non-electrode portion and the electrode portion of the upper electrode substrate, respectively, and FIG. 5 is an explanatory diagram of the manufacturing process of the electrode substrate for a liquid crystal display element according to the present invention. 1, 1'... Glass substrate, 2, 2'... Transparent electrode, 3, 3'... Vertical alignment agent layer, 4... CNT type liquid crystal, 5... Lines of electric force, 6... Focal conic part , 7, 7'... Insulating convex portion, 8, 8'... Colored coating, 9, 9'... Electrode substrate, 21... Transparent substrate,
22... Non-transparent electrode layer, 23... Negative photosensitive resin coating, 23'... Cured resin protrusion, 24... Colored coating, 24'... Colored coating on the protrusion.

Claims (1)

[Claims] 1. A transparent substrate having a predetermined thickness on the surface containing the electrode of a transparent substrate provided with an electrode made of a conductive layer having a pattern corresponding to a predetermined electrode pattern on the surface and having a region opaque to light in at least a certain wavelength range. A negative photosensitive resin coating having a photosensitive wavelength is provided in the impermeable region of the conductive layer, a colored coating is further provided on the coating, and then a photosensitive resin of the negative photosensitive resin is applied from the back side of the substrate. After exposing with light having a photosensitive wavelength and not passing through the conductive layer in the wavelength range, developing the photosensitive resin film and removing the photosensitive resin film on the non-transparent electrode on the surface of the substrate. A method for manufacturing an electrode substrate for a liquid crystal display element, characterized in that a convex portion made of the photosensitive resin and having a colored film on the surface is provided on a non-electrode portion of the substrate.