JPH10161101A - Liquid crystal display element, its production and liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an element structure suitable for a photopolymerization phase sepn. method. SOLUTION: The TFT(thin film transistor) liquid crystal display element having a liquid crystal/resin composite has zero overhang regions 4 where the ends of array side light shielding films 1 and counter side light shielding films 2 are aligned and one side light shielding regions 3 where light is shielded by only either of both. these one side light shielding regions 3 have boundary regions (k0 , k1 ...) including rectangular shapes (width of S>=2μm and length of L>=2μm) along apertures. The total of Ln per pixel is >=40μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a liquid crystal / resin composite formed by photopolymerization phase separation as an electro-optical function layer, and more particularly to a liquid crystal / resin composite directly related to a display function. It relates to the relationship between the manufacturing method and the element structure.

[0002]

2. Description of the Related Art Liquid crystal displays have low power consumption.
It is widely used in personal computers, pocket TVs, and the like, making use of features such as low-voltage driving. Among them, an active matrix liquid crystal display element in which an active element is arranged for each pixel electrode has attracted attention and is being actively developed.

At present, a widely used twisted nematic or super twisted nematic liquid crystal display device (TN-LCD, STN-LCD) requires two polarizing plates and therefore has a low light transmittance. Has problems. In particular, when an image is projected and displayed, an extremely strong light source is required so as to compensate for the loss of light in the polarizing plate.

[0004] In addition, since the TN-LCD operates in a mode utilizing light absorption-transmission characteristics to perform display, it is difficult to obtain a high contrast on a projection screen, and the TN-LCD has a problem in that a heat generated by a light source may cause the liquid crystal display element to emit light. There are problems such as influence, temperature rise of the liquid crystal display element itself, and the like.

[0005] In order to solve the problem of TN-LCD, a liquid crystal / resin composite in which a nematic liquid crystal is dispersed and held in a resin phase is used as an electro-optical function layer to reduce light scattering.
A liquid crystal / resin composite element utilizing transmission characteristics has been proposed. It is also called a dispersion type liquid crystal display element.

[0006] This liquid crystal / resin composite is manufactured as follows. A nematic liquid crystal, a curable compound to be a resin phase, and a polymerization initiator are mixed to form a compatible and substantially uniform solution or latex. Next, this is photo-cured, heat-cured, cured by removing a solvent, and reaction-cured to separate the resin phase and the liquid crystal phase, thereby forming a state in which the resin phase and the liquid crystal phase of the nematic liquid crystal are dispersed.

It is preferable to use a photo-curing or heat-curing resin, because the resin can be cured in a closed system. In particular, the use of a photo-curing type resin is preferable because it can be cured in a short time without being affected by heat.

As a specific manufacturing method, a cell is formed using a sealing material in the same manner as a conventional ordinary nematic liquid crystal, and an uncured mixture of a nematic liquid crystal and a resin matrix is injected from an injection port. After sealing, it can be cured by irradiating light or heating.

At present, a production method using phase separation by photo-curing is widely practiced in view of the fact that the obtained element has excellent electro-optical characteristics and reliability. JP-A-63-27123
No. 3 discloses an invention in which a liquid crystal / resin composite is formed by using a photocurable acryloyl-based compound or an acrylic oligomer and using a photopolymerization phase separation method.

Japanese Patent Application Laid-Open No. Hei 8-136873 discloses an invention for producing a liquid crystal / resin composite by photopolymerization phase separation in water. Japanese Patent Application Laid-Open No. 3-98022 discloses 2-hydroxyethyl acrylate (2HE
A), 2-ethylhexyl acrylate (2EHA), and liquid crystal are mixed to form a substantially uniform compatible mixture, which is irradiated with ultraviolet rays to cause polymerization phase separation, thereby forming a liquid crystal / polymer composite element, and forming a liquid crystal / polymer composite element. A liquid crystal display element combined with a TFT array provided with a light-shielding film in the periphery and a projection type liquid crystal display device using the same are disclosed.

Japanese Patent Application Laid-Open No. Hei 6-186535 discloses a liquid crystal physical property preferable for a liquid crystal / resin composite.
No. 4238 discloses preferable polymer properties for a liquid crystal / resin composite.

Japanese Patent Application No. 7-98894 discloses that 2,2,4-trimethyl 1,2 is used as a photocurable compound.
An invention using 6-diisocyanatohexane (TMDI) is shown.

Japanese Patent Application Laid-Open No. Hei 8-101405 discloses that in a liquid crystal display device provided with a liquid crystal / resin composite in combination with a TFT array, the influence of a light-shielding film provided around a TFT on polymerization phase separation is examined. An invention is shown in which the arrangement of each electrode is improved in order to reduce the number of electrodes.

[0014]

An object of the present invention is to improve the display characteristics of a liquid crystal display device having a liquid crystal / resin composite. Unlike conventional TN-LCD and STN-LCD,
A liquid crystal / resin composite functioning as an electro-optical function layer has a liquid crystal layer and a resin phase, and the structure directly affects optical characteristics.

In the case of a liquid crystal / resin composite formed by a polymerization phase separation method in a liquid crystal cell, the layout configuration conditions of each member in the cell required at the time of formation and the element structure required as the performance of the display element. Attempts to satisfy both conditions.

For example, a black matrix (B) is provided on the substrate on the side opposite to the active matrix type liquid crystal display element.
A light shielding means and a color filter called M) are formed. Semiconductor circuit elements constituting the TFT are provided on an array substrate on which active elements such as a two-terminal element MIM and a three-terminal element thin film transistor (TFT) are arranged, and further, a scanning line, a signal line, and an auxiliary dose wiring are provided. For example, a pattern using a material having a high light-shielding property such as aluminum or chromium is formed.

On a counter substrate facing the array substrate, for example, when a liquid crystal display element is used as a liquid crystal projector, it is necessary to prevent the occurrence of a light leakage current of a TFT. Is formed.

Since a shaded portion is formed by being optically covered with the light-shielding film, a liquid crystal / resin composite can be formed at the time of formation.
That is, when the mixture of the liquid crystal and the photocurable compound is irradiated with ultraviolet rays to be polymerized, an unpolymerized residue is present in a portion between the TFT and the light-shielding film.

As a method for solving such a problem, the display mode of the liquid crystal / resin composite is a normally black mode in which a dark display is performed when no voltage is applied, and only the TFT is provided on the TFT. There is a conventional technique using a counter substrate on which a light-shielding film is formed.

However, in the case of this configuration, there is a problem that a crosstalk occurs when a white window is displayed on a black background on the screen.

This is because even if the liquid crystal / resin composite displays normally black, the distance between the scanning line and the pixel electrode is usually shorter than the cell gap, so that the liquid crystal molecules are aligned by the lateral electric field effect. However, black display cannot be maintained.

Therefore, in order to obtain good display quality,
In order to prevent the display quality from deteriorating due to the lateral electric field effect, it is necessary to form a BM on the counter substrate side. However, in this case, in many cases, the light-shielding film formed on the counter substrate and the opening formed by the light-shielding film formed on the array substrate coincide with each other. When the ratio is 50% or more, a large amount of unpolymerized residue is generated during light irradiation during the formation of the liquid crystal / resin composite, and
The leakage light of the irradiation light causes a low scattering portion at an overlapping portion of the light shielding portion on the array substrate side and the light shielding portion on the opposite substrate side, which causes deterioration in display quality.

[0023]

In order to solve the above problems, the present invention provides a first substrate provided with a first electrode;
A liquid crystal display device in which a liquid crystal / resin composite formed by a polymerization phase separation method is sandwiched between a second substrate provided with a second electrode and a first light-shielding film provided on the first substrate Is provided, a second light-shielding film is provided on the second substrate, a one-sided light-shielded region shielded by only one of the light-shielded films is provided around the pixel opening, and the one-sided light-shielded region is provided on two sides. Has a boundary region including a rectangle having a length of S and L (S ≧ 2 μm, L ≧ 2 μm, and a side along the peripheral direction of the opening is L), and a total of L of the boundary region in one pixel ΣL
Is 40 μm or more.

In the above liquid crystal display device, the first
The first substrate is an array substrate provided with row electrodes and column electrodes arranged in a matrix, the first electrode is a pixel electrode, the pixel electrode is driven by an active element, the second substrate is a counter substrate, and the second substrate is a second substrate. A liquid crystal display element is provided, wherein the electrode is a common electrode, the first light-shielding film is an array-side light-shielding film, and the second light-shielding film is an opposing-side light-shielding film.

Further, in the above-mentioned liquid crystal display device, there is provided a liquid crystal display device wherein the aperture ratio of a pixel is 60% or more. Further, in the above liquid crystal display element,
Provided is a liquid crystal display element, wherein the maximum length of the opening in the row or column direction is 10 to 30 μm.

Further, according to the present invention, a liquid crystal / resin composite is formed from a compatible mixture of a photocurable compound and liquid crystal between a first substrate with a first electrode and a second substrate with a second electrode. A method for producing a liquid crystal display element formed by a polymerization phase separation method, wherein a difference in light transmittance between constituent members on a first substrate side and a second substrate side is provided, and the compatible mixture is irradiated with light to polymerize. Provided is a method for manufacturing a liquid crystal display element, which comprises applying, to a liquid crystal display element, energy for accelerating a curing reaction of the photocurable compound after inducing phase separation.

Further, the present invention provides a liquid crystal projector comprising any one of the above liquid crystal display elements, a schlieren optical system, and a projection lens.

In a preferred embodiment of the liquid crystal display device of the present invention, the area of the boundary region including the rectangular shape is M
When _n (n ≧ 1), with a small size of the pixel electrode shape (approximately, 20 [mu] m pitch) in? M ≧ 80 [mu] m ^2, with those of the pixel electrode shapes of the medium-sized (approximately, 40 to 60 [mu] m pitch), 240 .mu.m ² ≧ ΔM ≧ 160 μm ² , large pixel electrode shape (approximately 100 μm pitch)
≧ 400 μm ² .

In a preferred embodiment of the liquid crystal display element of the present invention, when the area of the opening of the pixel is G, it is a small pixel electrode, G ≧ 400 μm ² , and a large pixel electrode. G ≧ 10000 μm ² .

In a preferred embodiment of the liquid crystal display device of the present invention, S ≧ 3 μm. In a preferred embodiment of the liquid crystal display device of the present invention, the diagonal size of the liquid crystal display device is 10 to 15, and the matrix of pixels is (640 to 1600) × (480 to 800).

In a preferred embodiment of the liquid crystal display device having an array substrate according to the present invention, the width of the row electrode is about 2 to 35 μm, the width of the column electrode is 2 to 25 μm, and the cell gap is 5 μm. -20 μm, preferably 8-14
μm. Next, the present invention will be described with reference to the drawings.

FIG. 1 is a plan view schematically showing a light-shielding film in a pixel portion of a liquid crystal display device of the present invention. A TFT and a pixel electrode are arranged at each intersection of a row electrode (gate bus) and a column electrode (source bus) arranged in a matrix (TFT
Of the detailed structure is omitted).

This figure shows a case where the array side light-shielding film and the opposing side light-shielding film are parallel projected and overlapped on the same plane which is flat on the substrate surface. In the figure, a hatched portion is a one-side light-shielding region, and a boundary region (k ₁ , k _2, ..., K) that can include a rectangular shape having a certain area (the lengths S and L of two sides) or more.
_n ).

That is, an active matrix type liquid crystal display device having a liquid crystal / resin composite, wherein the array side light-shielding film 1 and the opposite side light-shielding film 2 have the same zero-overhang region 4 and one of the two. and a one-sided light-shielding regions 3 are shielded by the mini, side light shielding film 3 (the width of the S ≧ 2μm, L ≧ 2μm in length) rectangles along the opening encompassing the boundary region (k _0, k ₁ ...) has, at a total of L _n per pixel 40μm or more. In this case, it is possible to use the value of the effective length L _X, such as to surround the opening at the position of the S / 2 as an approximation of L _n.

As described above, when the array-side light-shielding film is projected in parallel to the opposing-side light-shielding film, a region whose end is almost perfect and a one-side light-shielding region arranged so that only one of the light-shielding films protrudes. There is. In the present invention, by providing the boundary region in each pixel, the structure controllability of the liquid crystal / resin composite in the vicinity of the opening (the end of the pixel electrode) can be enhanced, and high optical performance can be achieved.

Further, in order to increase the degree of polymerization of the resin in the vicinity of the boundary region and to stabilize the structure of the liquid crystal / resin composite, after exciting the phase separation process by photopolymerization, as shown in FIG. It is more preferable to perform after-curing on the entire liquid crystal / resin composite layer in the liquid crystal cell.

FIG. 2 shows a comparative example in which the area where the end of the opening is tight (zero overhang area, abbreviated as ZOH) is long. In this case, the photopolymerization phase separation process near the ZOH is as follows. First, simultaneously with the polymerization of the curable compound in the opening, an unpolymerized curable compound (monomer or oligomer) is supplied from a region covered with the light-shielding film. As a result, the amount of resin becomes excessive in the vicinity of ZOH, and a liquid crystal / resin composite having different light scattering characteristics is formed after phase separation.

Therefore, the light scattering characteristics in the pixel become non-uniform near the opening of the pixel, and the obtained liquid crystal display element has
The display characteristics also deteriorate over the entire display surface. Such a liquid crystal display element can perform a certain operation, but cannot achieve a display of a quality required for practical use.

FIG. 3 is a schematic plan view of the array-side light-shielding film of the liquid crystal display device (the plan view of the pixel portion) shown in FIG. 1, and FIG. 4 is a schematic plan view of the opposite light-shielding film. FIG. 5 is an example of the present invention in which the shape of the pixel electrode is further deformed, and the step around the opening is small and smooth. It is more suitable for photopolymerization phase separation and has good display characteristics.

[0040]

According to the present invention, a large amount of unpolymerized residue is generated during light irradiation during the formation of the liquid crystal / resin composite, or the array side light-shielding film and the opposing side light-shielding film are caused by leakage of irradiation light. A liquid crystal display device with high display quality can be produced without causing a low scattering portion in an overlapping region, that is, a portion having an overlapping area when projected on a plan view.

By employing a two-stage polymerization process, a liquid crystal display device and a liquid crystal projector having more uniform display characteristics and high optical performance can be manufactured. Each example will be described below. Examples 1-4, Examples 5, 7, 8, Examples 1A-4A, 5
A, 7A, 8A and Example 9 are the present invention. Example 6, 6A
Is a comparative example.

(Example 1) A scanning line, an auxiliary capacitance electrode, a source electrode, a drain electrode, a TF
Forming a T, a pixel electrode, a signal line, and an array side light shielding film,
An array substrate was manufactured. In addition, a counter electrode and a light shielding film on the opposite side were formed on the other glass substrate to produce a counter substrate.

At this time, a lattice pattern was provided using Cr for the light shielding film serving as the array side light shielding film. The opposite side light-shielding film on the opposite substrate side was made of Cr and provided with a grid-like pattern substantially equivalent to a pixel-shaped inverted pattern. An arrangement similar to that of FIG. 1 was employed.

The width of the row electrode is 2 μm, and the width of the column electrode is 2 μm.
m, the pixel electrode is about 20 μm × 20 μm, and the area is 40
It was set to 0 μm ² . The diagonal size of the liquid crystal display element was 1.3 size, and the number of pixels in the vertical and horizontal directions was 1024 × 768 (XGA).

The design was made so that the width of the overlapping portion between the array-side light-shielding film and the opposing-side light-shielding film was 80% of the length of the periphery of the pixel electrode where the width was 2 μm or more.

The two substrates are bonded together via a spacer to form an empty cell with a cell gap of 20 μm. Further, using BL002 (manufactured by Merck) as a liquid crystal, a photocurable acryloyl-based monomer and photocurable HEA and M-1200 (Toagosei Co., Ltd.)
The cell was uniformly dissolved using the method described above and filled in the cell.

The cell was irradiated with ultraviolet rays from both sides of the substrate, and a liquid crystal / resin composite was formed by a photopolymerization phase separation method. The above-described conventional irradiation-in-water irradiation polymerization phase separation method was used.

Using a liquid crystal display device provided with the thus obtained liquid crystal / resin composite as an electric function optical layer,
A liquid crystal projector was assembled by combining a schlieren optical system (aperture system), a light source such as a metal halide lamp, and a color separation / combination optical system such as a dichroic mirror. When the projection image was evaluated, a good display image with high contrast could be obtained.

Next, by changing the conditions, various liquid crystal / resin composite-TFT array cells were manufactured. In Examples 2 to 4, the arrangement configuration shown in FIG. Examples 5-8 contrasted for a two-step process. Table 1 below,
The results are shown in Table 2. The upward arrow indicates that it has the same configuration as the upper column. It was found that a stable liquid crystal / resin composite layer could be formed by using the two-stage polymerization process even with the arrangement shown in FIG.

[0050]

[Table 1]

[0051]

[Table 2]

(Examples 1A to 8A) The continuous production of Examples 1 to 8 described above was carried out. The preparation of the compatible mixture of the liquid crystal and the curable compound is carried out at the time of polymerization phase separation so that the applied voltage-light transmittance characteristic (VT curve), which is the optical characteristic of the obtained liquid crystal / resin composite, becomes almost equal. Temperature conditions and light irradiation intensity were adjusted for each lot of each composition solution.

As a result, a liquid crystal display element having almost constant optical characteristics except for Example 6A could be manufactured, despite the existence of a light-shielding film that hinders light irradiation in the pixels of each liquid crystal display element. .

(Example 9) A light reflection layer was provided on the array substrate side,
A reflective liquid crystal display device was manufactured. In this example, a flattening film is laminated on the TFT, a reflective electrode is formed thereon,
The via hole was connected to the drain electrode of the FT. For this configuration, the photopolymerization phase separation was performed by irradiating light only from the counter substrate side.

However, the obtained liquid crystal / resin composite had sufficient structural uniformity and exhibited light scattering characteristics comparable to those of the transmission type. In addition, because of the reflection type, a high contrast ratio could be achieved.

Comparative Example 1 A scanning line, an auxiliary capacitance electrode, a source electrode, a drain electrode, a TF
T pixel electrodes and signal lines were formed to produce an array substrate.
In addition, a counter electrode and a BM were formed on the other glass substrate to produce a counter substrate.

At this time, a region where the width of the overlapping portion of the light shielding member formed on the array substrate and the light shielding member formed on the counter substrate is 2 μm or more is 30 μm, which is the circumference length of the pixel electrode. %Met.

The two substrates were bonded to each other via a spacer to form a cell, and a cell obtained by uniformly dissolving liquid crystal, a photocurable acrylic monomer, and an acrylic oligomer was filled in the cell. This was irradiated with ultraviolet rays from both sides of the substrate to obtain a liquid crystal resin composite.

Using the liquid crystal resin composite obtained in this manner, a projection type liquid crystal display device was assembled using a metal halide lamp, a dichroic mirror, and the like, and the projection image was evaluated. Was large and the display image was low in contrast.

[0060]

As described above, according to the present invention, transmission-
In the scattering type liquid crystal display device, the unpolymerized region can be reduced when the liquid crystal resin composite is formed, and a liquid crystal display device having good contrast can be obtained.

The present invention can be applied to various applications within a range not to impair the effect.

[Brief description of the drawings]

FIG. 1 is a plan view of a pixel portion of a liquid crystal display device of the present invention.

FIG. 2 is a plan view of a pixel portion of a comparative example.

FIG. 3 is a plan view of an array-side light-shielding film of the liquid crystal display element of the present invention.

FIG. 4 is a plan view of an opposing light-shielding film of the liquid crystal display element of the present invention.

FIG. 5 is another plan view of the opposing light-shielding film of the liquid crystal display element of the present invention.

FIG. 6 is a block diagram showing a manufacturing flow of the liquid crystal display element of the present invention.

[Explanation of symbols]

 1: Array side light shielding film 2: Opposite side light shielding film 3: One side light shielding region 4: Zero overhang region

Claims (6)

[Claims] 1. A liquid crystal / resin composite formed by a polymerization phase separation method is sandwiched between a first substrate provided with a first electrode and a second substrate provided with a second electrode. Liquid crystal display device, wherein a first light-shielding film is provided on a first substrate, a second light-shielding film is provided on a second substrate, and one-sided light-shielding is performed by only one of the light-shielding films. An area is provided around the opening of the pixel, and the one-sided light-shielding area is a rectangle having two sides S and L (S ≧ 2 μm, L ≧ 2 μm, and the side along the peripheral direction of the opening is L). ), Wherein a total ΔL of L of the boundary region in one pixel is 40 μm or more. 2. A method according to claim 1, wherein the first substrate is an array substrate provided with row and column electrodes arranged in a matrix, the first electrode is a pixel electrode, and the pixel electrode is driven by an active element.
2. The liquid crystal according to claim 1, wherein the first substrate is an opposing substrate, the second electrode is a common electrode, the first light shielding film is an array side light shielding film, and the second light shielding film is an opposite side light shielding film. Display element. 3. The liquid crystal display device according to claim 1, wherein the aperture ratio of the pixel is 60% or more. 4. The maximum length of the opening in the row or column direction is 10 to 3
4. The liquid crystal display device according to claim 1, wherein the thickness is 0 [mu] m. 5. A method for polymerizing a liquid crystal / resin composite from a compatible mixture of a photocurable compound and a liquid crystal between a first substrate with a first electrode and a second substrate with a second electrode. A method of manufacturing a liquid crystal display element formed by the method described above, wherein the first and second substrates have different light transmittances, and the compatible mixture is irradiated with light to induce polymerization phase separation. A method for producing a liquid crystal display element, comprising applying, to the liquid crystal display element, energy for accelerating the curing reaction of the photocurable compound. 6. A liquid crystal projector comprising: the liquid crystal display device according to claim 2; a schlieren optical system; and a projection lens.