JPH0475024A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the display element which is large in effective aperture rate and does not have its liquid crystal layer affected adversely by a color filter by equipping either of a couple of transparent substrates with a microlens array and the color filter internally. CONSTITUTION:A liquid crystal layer 6 is provided between a transparent substrate 1 and the substrate 8 which has the microlens array 2 and color filter 10 internally and many picture elements are formed in the liquid crystal panel consisting of the substrates 1 and 8 and liquid crystal layer 6. The microlens array 2 has microlenses 9 which converge light on the respective picture elements, the color filter 10 are provided corresponding to the respective, and the focus of each microlens 9 is positioned nearby the surface of the substrate 8 on the side of the liquid crystal layer 6. Consequently, no impurities are dissolved out of the color filter 10 into the liquid crystal layer 6 and no adverse influence is exerted upon a display; and a light convergence spot can be made smaller than each picture element and the effective aperture rate can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high ytm projection type color liquid crystal display element with excellent light resistance.

(Prior Art) Demand for liquid crystal panels is increasing not only for direct view type display devices but also for projection type display devices such as projection televisions. When using a projection-type LCD panel, increasing the magnification with the conventional number of picture elements makes the screen rougher.

In order to obtain a fine image even at a high magnification ratio, it is necessary to increase the number of picture elements.

However, when the number of pixels in an LCD panel increases, especially in an active matrix type LCD panel, the area where areas other than pixels become obsolete becomes relatively large, and the area of the black mask that covers these areas increases. . When the area of the black mask increases, the area of picture elements contributing to display decreases, and the aperture ratio of the display element decreases. When the aperture ratio decreases, the screen becomes dark and the image quality deteriorates.

In order to prevent the aperture ratio from decreasing due to the increase in the number of picture elements, it has been proposed to form a microlens array on one side of the liquid crystal panel (Japanese Patent Application Laid-Open No. 60-165).
621-165624).

The microlens array has a microlens corresponding to each picture element, and it becomes possible to focus light, which was conventionally blocked by a blank mask, into the picture element.

The ion exchange method (Ap
pl, 0ptics 21(6), p, 1Q52(1
984), or ε1eetron Lett, 17.
p, 452 (1981)), swelling method (lead powder et al., “
A new method for producing plastic microlenses “24th Micro-Optics Research Group”, thermal blur method (Zoran D.

Popovic et al, -Technique
for monolithic fabric + cat1o
n of m1crolenz arrays, A
ppl, 0ptics 27p, 1281 (198g
)), vapor deposition method (JP-A-55-135808), thermal transfer method (JP-A-61-64158), machining method, etc.

In the ion exchange method, a substrate containing ions is brought into contact with another ion source, a voltage is applied, and a lens effect is produced by the refractive index distribution produced by the ion exchange. In the swelling method, a photosensitive monomer is polymerized with ultraviolet rays, and the difference in osmotic pressure generated between the exposed and non-exposed areas causes the exposed areas to swell, resulting in a convex lens shape. In the thermal sag method, a photosensitive resin film is patterned into a circular shape, and then heated and melted to a temperature higher than the melting point of the resin to obtain a lens shape due to surface tension. In the vapor deposition method, a lens is formed by depositing a glassy material by vapor deposition until a rotor-shaped recess made on a glass substrate is filled, and then reducing the glass substrate to its original thickness. In the machining method, lenses are formed by cutting the base material.

The ion exchange method and the vapor deposition method yield a flat microlens array having refractive index gradient microlenses, and the other methods yield a microlens array having monospherical microlenses. In the case of a microlens array having hemispherical microlenses, mass production of the microlens array becomes possible by creating a mold based on this and molding using this mold. By bonding these microlens arrays to the outer surface of a liquid crystal panel, the effective aperture ratio is the same as above, and a bright display screen can be obtained.

However, even if a microlens array is attached to the outer surface of currently used liquid crystal panels, there is a limit to the improvement of the effective aperture ratio. This is because light has a diffraction limit, and the size of the focused spot is determined by itself. The smaller the diameter of the microlens, the smaller the focal spot size.
And the longer the focal length, the larger it becomes. If the size of the light spot becomes larger than the area of the picture element, all the light cannot contribute to display, making it impossible to improve the effective aperture ratio.

In order to enhance the light condensing effect, it is possible to increase the diameter of the microlens, decrease the focal length, etc. However, the diameter of the microlens is larger than the area of the picture element (there is a restriction that it cannot be made larger than the area of the pixel. Also, the focal point of the microlens is near the liquid crystal layer side of the substrate on which the microlens is attached). The focal length of the microlens cannot be less than the thickness of this substrate.The thickness of the glass substrate used in liquid crystal panels is approximately 1tin+, and the focal length of the microlens cannot be less than the thickness of this substrate. Even if it is thin, it is practically 0°5!1II
l would be the limit. Therefore, the focal length of the microlens cannot be made shorter than that. In a liquid crystal panel that performs high-definition display in which the pitch of picture elements is on the order of several tens of micrometers, the condensed spot cannot be made smaller than a certain level due to the diffraction limit, and the spot becomes larger than the area of the picture elements.

(Problem H to be solved by the invention) In order to solve these problems, a liquid crystal display element in which a microlens array is provided inside one of the transparent substrates that constitute the liquid crystal panel has been developed (patent application). Hei 2-468
No. 68). FIG. 2 shows a cross-sectional view of a liquid crystal display element having such a configuration.

This liquid crystal display element is of an active matrix type. Although not shown, picture element electrodes, switching elements, bus wiring, etc. are formed on the transparent substrate 1. Board 1
A liquid crystal layer 6 is sealed with a sealing material 5.

The counter substrate 8 consists of a microlens array 2, an adhesive layer 4, and a plastic film 3. In the microlens array 2, microlenses 9 having the shape of convex lenses are formed corresponding to each picture element electrode on the substrate 1. A plastic film 3 is attached to the microlens array 2 with an adhesive layer 4 made of transparent resin.

In such a configuration, since the microlens 9 is provided near the liquid crystal layer 6, the focal length of the microlens 9 can be made small, and the condensed spot can be made small.

Such a liquid crystal display element can be used as a color liquid crystal display element in combination with a color filter. However, when this color liquid crystal display element is used as a projection type liquid crystal display element, the light resistance of the color filter becomes a problem because the color filter is irradiated with light of considerable intensity. Dye-type color filters, which have been conventionally often used in direct-view liquid crystal display panels, cannot be used because of their low light resistance.

Therefore, in order to project a color image, it is conceivable to use an interference type color filter or a pigment dispersion type color filter that has excellent light resistance.

Furthermore, a method is also used in which three liquid crystal display panels corresponding to the three primary colors are used without using color filters. However, a color liquid crystal display element using an interference type color filter or a color liquid crystal display element using three liquid crystal display panels has a problem of high cost. In addition, in color liquid crystal display elements using dispersed color filters, it is necessary to provide the color filter on the liquid crystal layer side of the liquid crystal panel substrate to avoid parallax, so impurities are removed from the dispersed color filters. There is a problem that it elutes into the layer and adversely affects the display.

The present invention solves these problems, and an object of the present invention is to provide a color liquid crystal display element with a large effective aperture ratio, in which the color filter does not have an adverse effect on the liquid crystal layer. The goal is to provide the following.

(Means for Solving the Problems) The color liquid crystal display element of the present invention includes a liquid crystal panel having a liquid crystal layer between a pair of transparent substrates and in which a large number of picture elements are formed, and a liquid crystal panel that focuses light on each of the picture elements. A color liquid crystal display element comprising a microlens array having microlenses to make the picture element transparent, and a color filter corresponding to each of the picture elements, wherein one of the pair of transparent substrates has a color filter inside the transparent substrate. It has a microlens array and the color filter, and the focal point of the microlens is located near the surface of the one substrate on the liquid crystal layer side, thereby achieving the above object.

(Function) Since the color liquid crystal display element of the present invention has a color filter inside the substrate, the color filter and the liquid crystal layer do not come into contact with each other. Therefore, impurities will not be eluted from the color filter into the liquid crystal layer and will not adversely affect the display.

Furthermore, since the color liquid crystal display element of the present invention has a microlens array inside the substrate, the focal length of the microlens can be made small. Therefore, the focused spot can be made smaller than the size of the picture element, and the effective aperture ratio can be improved.

(Example) Examples of the present invention will be described below. FIG. 1 shows a sectional view of an embodiment of the color liquid crystal display element of the present invention. This embodiment is an active matrix type color liquid crystal display element. The color liquid crystal display element of this example has a transparent substrate 1
and a microlens array 2 and a color filter 1 inside.
A liquid crystal layer 6 is disposed between a substrate 8 and a substrate 8. Board 1
A large number of picture elements are formed on the liquid crystal panel constituted by the liquid crystal layer 6 and the liquid crystal layer 6. The microlens array 2 has microlenses 9 that focus light on each picture element. In this embodiment, the microlens 9 has a convex lens shape. A color filter 10 is provided corresponding to each picture element.

The focal point of each microlens 9 is located near the surface of the substrate 8 on the liquid crystal layer 6 side.@The transparent substrate 1 is made of borosilicate glass, and on it, although not shown, is a pixel electrode. , switching elements, bus wiring, etc. are formed. A liquid crystal layer 6 is enclosed by a sole material 5 between the substrate 1 and a counter substrate 8 facing the substrate 1. A transparent resin layer 11 is provided between the microlens array 2 of the substrate 8 and the color filter 10.

Further, the substrate 8 is connected to the adhesive layer 4 on the color filter 10,
It has a plastic film 3 pasted on an adhesive layer 4.

The microlens array 2 can be manufactured by the aforementioned swelling method, thermal sagging method, thermal transfer method, machining method, or the like.

In this example, a heat sagging method was used.

Transparent resin layer 11 provided on microlens array 2
are provided to flatten the uneven portions on the microlens array 2.

The color filter 10 formed on the transparent resin layer 11 is
It is produced using a negative type photosensitive resin, which is a mixture of resin, pigment, and photosensitizer. This photosensitive resin is applied onto the transparent resin layer ll and patterned by exposure.

This patterning consists of R (red), G (green) and B (blue).
is repeated for the three colors. A black mask (not shown) is formed in the gap between each color of the color filter 10 as necessary.

For the adhesive layer 4 that adheres the color filter 10 and the plastic film 3, an adhesive made of transparent resin can be used. Although the adhesive layer 4 is provided in this embodiment, the microlens array 2 and the plastic film 3 may be bonded together by other methods without providing the adhesive layer 4. In this example, an ultraviolet curing resin was used for the adhesive layer 4. Adhesive layer 4
Using thermosetting resin for microlens array 2
This is not preferable because there is a large difference in the coefficient of thermal expansion between the plastic film 3 and the plastic film 3.

The transparent substrate 1 is preferably made of a material having the same coefficient of thermal expansion as the substrate forming the microlens array 2. This is because if the difference in coefficient of thermal expansion between the substrate 1 and the substrate of the microlens array 2 is large, there is a possibility that the resulting color liquid crystal display element will have poor reliability with respect to temperature.

The plastic film 3 is required to have properties such as high optical transparency, isotropy or uniaxial orientation, excellent chemical resistance, low water absorption, and low air permeability. As a suitable material for plastic film 3,
Examples include polycarbonate resin, polysulfone resin, phenolic diether resin, and -axial polyester resin.

Instead of plastic film, thin glass can also be used. In this example, a polyether sulfonic acid resin film having a thickness of 013 m was used.

The thickness of the plastic film 3 is determined so that the rear focal point of the microlens 9 is located near the surface of the liquid crystal layer 6 of the plastic film 3, and preferably, the focal point is located at the center of the liquid crystal layer 6. It is decided to do so. When the adhesive layer 4 is not provided, the thickness of the plastic film 3 is set to the rear focal length fb of the microlens 9.
and the refractive index n of the plastic film 3, fb-
It is determined by n. Since the adhesive layer 4 is provided in this example, the thickness of the plastic film 3 was determined by taking its refractive index into consideration.

A transparent electrode (not shown) is formed on the surface of the plastic film 3 on the liquid crystal layer 6 side. This transparent electrode may be formed either before or after bonding the microlens array 2 and plastic film 3 together. Plasti 1. Since the film 3 has a low heat resistance, the transparent electrode was formed by low-temperature vapor deposition. Furthermore, the alignment film and sealing material 5 formed on the counter electrode were of a low temperature curing type and had excellent adhesion to the plastic film 3.

In this embodiment, a microlens array 2 having convex lens-shaped microlenses 9 is used, but a flat plate microlens array manufactured by an ion exchange method, a vapor deposition method, or the like may also be used. The use of a flat plate microlens array eliminates the need to provide the transparent resin layer 9, and has the advantage that the color filter 10 can be easily formed. However, when using a flat plate microlens array produced by an ion exchange method, the substrate for forming the flat plate microlens contains many ionic components, so the transparent substrate for forming picture element electrodes, switching elements, etc. There is a difference in thermal expansion coefficient between Therefore, the temperature reliability of the resulting liquid crystal display element may be poor. In order to prevent such a decrease in reliability, it is preferable to use a highly elastic spacer for keeping the thickness between the sealing material 5 and the substrates 1 and 8 constant.

The color liquid crystal display element of this embodiment has a color filter 10 corresponding to each picture element in a substrate 8.
Since the plastic film 3 is provided on the liquid crystal layer 6, impurities will not be eluted from the color filter 10 into the liquid crystal layer 6. Therefore, it is possible to use a dispersion type color filter 10 that is inexpensive and has excellent light resistance.

Further, since the substrate 8 has the microlens array 2 therein, the focal length of the microlens 9 can be reduced, and the effective aperture ratio of the color liquid crystal display element can be improved.

Although the present embodiment uses a nodule dispersion type color filter, other types of color filters, such as interference type color filters, may also be used.

(Effects of the Invention) The color liquid crystal display element of the present invention has a color filter inside one of the pair of transparent substrates, and since there is no elution of impurities from the color filter, the color liquid crystal display element is inexpensive and has excellent light resistance. type color filters can be used. Therefore, according to the present invention, a liquid crystal display element with excellent light resistance can be provided at low cost. Further, since the color liquid crystal display element of the present invention has a microlens with a small focal length, it is possible to obtain a color liquid crystal display element having a bright display screen.

4. No, no! 1 is a sectional view of one embodiment of the color liquid crystal display element of the present invention, and FIG. 2 is a sectional view of an improved example of the liquid crystal display element.

Claims (1)

[Scope of Claims] 1. A liquid crystal panel having a liquid crystal layer between a pair of transparent substrates and forming a large number of picture elements, and a microlens array having microlenses that focus light on each of the picture elements; A color liquid crystal display element comprising a color filter corresponding to each of the picture elements, wherein one of the pair of transparent substrates has the microlens array and the color filter therein. and a color liquid crystal display element in which the focal point of the microlens is located near the surface of the one substrate on the liquid crystal layer side.