JPH1039286A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contrast from being lowered while remarkably reducing visual angle dependence by a microlens array sheet (MAL) by controlling the angle dependence of the transmissivity of a liquid crystal cell so as to have a specific ratio when it is expressed in the change rate of a contrast ratio in the range of specific angles arround the normal direction of a display surface. SOLUTION: This liquid crystal cell is the arrangement body of liquid crystal optical shutters in which light beam transmissivity is changed by changing oriented states of liquid crystals while impressing an electric field or passing a current in an arbitrary display unit. An MLA 10 is constituted by arranging minute unit lenses in a plane shape and mounted on the observation surface of the liquid crystal cell. The angle dependence of the transmissivity of the liquid crystal cell in the arrangement direction of the minute unit lenses of this MLA is controlled within 50% when it is expressed by the change rate of the contrast ratio in the range of ±15 degrees arround the normal direction of the display surface. Consequently, the contrast ratio is prevented from being lowered by the mounting of the MAL 10 and the visual field enlarging effect of the MLA 10 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device uses an electro-optical effect of liquid crystal molecules, that is, optical anisotropy (refractive index anisotropy), orientation, fluidity, dielectric anisotropy, and the like, to provide an arbitrary display. It observes images displayed using an array of liquid crystal optical shutters that changes the light transmittance and reflectivity by changing the alignment state of the liquid crystal by applying an electric field or applying electricity to the unit, and it can be used for personal computers, word processors, It is widely used as a television receiver, a portable electronic device, a game machine, an in-vehicle information display device, and various information display devices.

As a display principle of a liquid crystal display device, a twisted nematic liquid crystal that performs display by controlling a voltage applied to a nematic liquid crystal layer twisted by about 90 degrees and combining a change in the optical rotation of the liquid crystal layer with a polarizing element is known. It is widely used because of its high display performance.

However, a liquid crystal display device has a viewing angle dependency in which the display quality changes depending on the viewing direction. In particular, in the case of a twisted nematic liquid crystal, the display brightness is reversed,
There is a problem that the color tone changes, that is, a problem that the viewing angle is narrow.

It is known that the viewing angle dependency of a liquid crystal cell is changed by disposing an optical compensation element having birefringence anisotropy between a polarizing element and a liquid crystal cell.

Japanese Patent Application Laid-Open No. 5-249453 discloses that a liquid crystal display device having a wide viewing angle can be obtained by using a microlens array sheet in which minute unit lenses mounted on an observation surface of a liquid crystal cell are arranged in a plane. Is known by:

Further, as a microlens array sheet, a first material layer and a second material layer having a lower refractive index than the first material layer are sandwiched between two parallel planes, and the first material layer and the second material layer A micro unit lens functioning as a lens by forming a concave and / or convex surface at the interface of the layers is arranged in a plane, and the second material layer side of the micro lens array sheet is turned to the liquid crystal cell, It is known from JP-A-6-27454 and the like that a liquid crystal display device having an enlarged viewing angle can be obtained by mounting the material layer side to the observation direction side while suppressing deterioration in image quality.

[0008]

However, by simply mounting the microlens array sheet according to the prior art on the observation surface, the viewing angle dependency is greatly reduced, but the display quality is reduced. That is, there is a problem that the image quality when viewed from the normal direction of the display surface, which is the most frequently observed (hereinafter, simply referred to as “front” or “front of screen”), is deteriorated.

The present invention has been made to overcome the drawbacks of the prior art and to provide a liquid crystal display device in which the viewing angle dependency is greatly reduced by the microlens array sheet, but which does not cause a decrease in contrast. Things.

[0010]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the liquid crystal display device of the present invention includes a liquid crystal cell which is an array of liquid crystal optical shutters that changes the alignment of the liquid crystal by applying an electric field or applying an electric current to an arbitrary display unit, thereby changing the light transmittance. A microlens array sheet, which is formed by arranging the microunit lenses mounted on the observation surface of the liquid crystal cell in a planar manner, the microlens array sheet comprising: a microunit of the microlens array sheet. When the angle dependence of the transmittance of the liquid crystal cell in the lens array direction is represented by the change ratio of the contrast ratio in a range of ± 15 degrees around the normal direction of the display surface, 5
It is characterized by being controlled within 0%.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is intended to provide a liquid crystal display device in which the viewing angle dependence is greatly reduced by a microlens array sheet, and that a liquid crystal display device which does not cause a decrease in contrast cannot be provided. When the angle dependency of the transmittance of the liquid crystal cell is represented by a specific condition, that is, a change ratio of the contrast ratio in a range of ± 15 degrees around the normal direction of the display surface, when controlled within 50%, Surprisingly, they have sought to solve these problems at once.

In the present invention, a "liquid crystal display device" is an optional device that utilizes the electro-optic effect of liquid crystal molecules, that is, optical anisotropy (refractive index anisotropy), orientation, fluidity, dielectric anisotropy, and the like. An image displayed directly using an array of liquid crystal optical shutters that changes the light transmittance or reflectivity by changing the alignment state of the liquid crystal by applying or applying an electric field to the display unit Refers to a display device.

Further, a "liquid crystal cell" refers to an array of the liquid crystal optical shutters.

The display unit of the liquid crystal cell is the minimum unit of the display content displayed on the liquid crystal display device. For example, in the case of a liquid crystal display device of many monochrome displays, one liquid crystal light shutter is used as a display unit. In the case of a color liquid crystal display device, a unit constituted by three liquid crystal optical shutters for displaying respective primary colors such as red, green and blue is a display unit.

In the present invention, a “microlens array sheet” (hereinafter, referred to as “MLA”) is a minute unit lens, that is, a minute unit portion having a lens function (hereinafter, “MLA”).
"Micro lens unit" or simply "lens unit"
Are arranged in a plane.

Here, "having a lens function" means that
Unlike a general monoconvex lens or monoconcave lens, it is not necessary to have a fixed focal point, but it is only necessary to have a function of refracting an incident light beam in an arbitrary controlled direction. Needless to say, so-called general `` diffusion plates '' and `` light scattering plates '', which are provided with light diffusing properties by disordered irregularities formed on the layer or surface to which light-scattering particles are added, randomly transmit incident light. Since it is scattered, it cannot be used in the present invention because it cannot be "refracted in any controlled direction" in the present invention.

The MLA used in the present invention includes a first material layer in which a unit lens is sandwiched between two parallel planes,
It is preferable that the second material layer having a refractive index smaller than the material layer has a concave surface and / or a convex surface to function as a lens. As the shape of the uneven surface, a one-dimensional lens array sheet in which curved surfaces represented by trajectories obtained by translating a curve such as an arc like a lenticular lens are arranged in one direction, and a low surface such as a rectangular, a triangle, a hexagon, etc. There is a two-dimensional lens array sheet in which dome-shaped curved surfaces having vertical and horizontal lines are arranged vertically and horizontally. Further, it may have a polyhedral shape in which planes and / or curved surfaces having various angles and curvatures are combined.

Here, the first material constituting the first material layer and the second material constituting the second material layer are substantially transparent materials, respectively. As the first substance, a glass material, a transparent plastic material, or the like is preferably used. As the second substance, any substance having a lower refractive index than that of the first substance may be used. In addition to a glass material and a transparent plastic material, a liquid such as water or a gas such as air can be used.

The layers of such first and second materials are sandwiched between two parallel planes. The interface is a concave surface and / or a convex surface. By adopting such a shape, it is possible to obtain a viewing angle widening effect when a liquid crystal display device is formed.
A large viewing angle widening effect can be obtained by mounting the material layer side with the observer side.

FIGS. 2 to 5 show the MLA used in the present invention.
Shows a shape example in the case where is one-dimensional. FIG. 2 and FIG. 3 are examples in which a columnar three-dimensional body is arranged in one direction, and a light-shielding layer 6 is formed on the lens arrangement surface to suppress reflection of external light. 4 and 5 show examples of the MLA in which the interface between the first substance and the second substance is a continuous curved surface. In the case of such an interface having a continuous curved surface, the interface between the first material layer and the second material layer of the unit lens has both a concave surface and a convex surface.
2 to 5, surfaces 4 and 5 of the first material layer 1 and the second material layer 2 different from the interface 3 are planes parallel to each other. In the case of the MLA of FIGS. 2 and 4, the unit lens arrangement direction is the horizontal direction on the paper. 6 to 8 show examples of shapes when the MLA used in the present invention is two-dimensional. As in the one-dimensional MLA shown in FIGS. 2 and 3, a light-shielding layer 6 is formed on the lens array surface to suppress reflection of external light. In the case of such a two-dimensional MLA, the unit lens arrangement direction is two axes orthogonal to each other in the horizontal direction on the paper and the vertical direction in the paper. Here, the flat surface means a substantially flat surface as compared with the uneven surface serving as a lens, and here, the average roughness R is relative to the height of the uneven surface.
When a is equal to or less than one-fifth, it is assumed to be a plane. Also, being parallel means that it is substantially parallel to the size of the unevenness.

The one-dimensional MLA is used when it is desired to widen the viewing angle in one direction of the display screen (the vertical direction or the horizontal direction of the screen) among the viewing angles of the liquid crystal cells to be combined. For example, in a case where the liquid crystal cell is a TN (twisted nematic) liquid crystal cell having a wide viewing angle in one direction, unit lenses are arranged in a direction orthogonal to the TN type.
By combining the dimensional MLA, a liquid crystal display device having a wide viewing angle in every direction can be obtained. When the application of the liquid crystal display device requires a wide viewing angle in only one direction, a one-dimensional MLA in which unit lenses are arranged in the required viewing angle direction is used.

When such an MLA is mounted on the observation surface of a liquid crystal cell with the second material layer facing the liquid crystal cell and the first material layer facing the observation surface, a large viewing angle expanding effect can be obtained.

The liquid crystal display device of the present invention has the M
One component is to mount the LA on the observation surface of the liquid crystal cell. However, depending on the structure of the MLA and the usage environment of the liquid crystal display device, external light incident from the observation surface of the liquid crystal display device is reflected by the uneven surface. This may make it difficult to see the display image on the liquid crystal display device. In such a case, ML
A can be provided with an appropriate external light reflection preventing function.

The external light reflection preventing function according to the following method can be used in the present invention, but is not limited thereto.

(1) A method of coloring any part of the reflection path of external light, which is not the path of the image light incident on the MLA from the liquid crystal cell side, black to block the reflection of external light. Here, “any part that is not the path of the image light” does not mean a part through which any light flux emitted from the liquid crystal cell does not pass, but a part through which a light flux emitted from the liquid crystal cell with a good display image does not pass. That means.

(2) A method of applying an anti-reflection coating with an optical multilayer thin film on the uneven surface (3) Coloring each unit lens of the microlens array,
Method of Reducing the Effect of External Light Reflection by Using External Light Reflection Path Length Longer Than Image Light Path Length (4) The top area of the convex portion of the first material of each unit lens of the microlens array is formed in the liquid crystal cell. (5) A first material layer having a refractive index higher than that of the first material layer is provided along the uneven surface of the first material layer, and the external light is applied to the first material layer. 'Method of encapsulating in the material layer In the case of (5), ML which is the second constituent requirement of the present invention
Although there is a portion where the interface between the first material layer and the second material layer of A does not exist, in the present invention, the interface between the first material layer and the second material layer is referred to in a broad sense as the first material layer and the second material layer. It shall be regarded as the interface of the material layer.

Of the above methods, the methods (1), (4), and (5) are preferable, and the method (1) is the most preferable, from the viewpoint of the obtained effects.

The liquid crystal display device of the present invention uses a liquid crystal cell in which the angle dependence of the transmittance is within 50% within a range of ± 15 degrees around the normal to the display surface. is important.

Here, the contrast ratio refers to the state of transmission with the highest transmittance when viewed from the front (this state is referred to as "white display state"), and the state with the lowest transmission when viewed from the front. The angle dependence is a numerical value obtained by dividing the transmittance by the transmittance of the display screen (referred to as “black display state”). The contrast ratio in each direction at a certain angle from the normal direction of the display surface is a function of the angle. To change.

Further, when a microlens or the like is mounted and the light is refracted when transmitting therethrough, the “transmittance” cannot be measured. In this case, the reference light source is placed on the back surface and the white display state is obtained. And the luminance ratio in the black display state.

However, in the present invention, the contrast ratio at a certain angle θ means an average value of the contrast ratio measured at θ + 5 degrees and the contrast ratio measured at θ-5 degrees. This is because, in actual use of the liquid crystal display device, since the viewing angle of the observer with respect to the screen differs depending on the position on the screen, a value close to the contrast ratio actually recognized by the observer is obtained.

Further, "the rate of change of the contrast ratio is 50%
Is within 100 "measured within this angular range.
% Means that the absolute value of the rate of change of the minimum value with respect to the maximum value is 50% or less, that is, the value represented by the following equation (1) is 50 or less. In the present invention, the angle dependence of the contrast ratio is
The measurement is performed in increments of 5 degrees with the normal direction of the display surface being 0 degree.

Rcr = (Max−Min) / Max × 100 (1) Here, Rcr represents a change ratio of the contrast ratio, Max represents a maximum value of the contrast ratio, and Min represents a minimum value of the contrast ratio.

By using such a liquid crystal cell, when combined with the MLA, the viewing angle can be made large and the deterioration of the image quality in the front, in particular, the deterioration of the contrast can be suppressed. The relationship between the liquid crystal cell characteristics and the effect is as follows.
It does not depend on the diffusion characteristics or transmission characteristics of MLA.

In order to make the liquid crystal cell used in the present invention,
In the case of a twisted nematic liquid crystal, there is a method in which one or several layers having an optically anisotropic layer, particularly a layer having a birefringent axis in a thickness direction or a direction inclined three-dimensionally, are interposed between the polarizing elements. Also, it does not prevent using a liquid crystal display mode other than the twisted nematic liquid crystal.

FIG. 9 is a diagram showing the viewing angle dependence of a twisted nematic liquid crystal (twist angle 90 °) which has been widely used conventionally. As can be seen from the figure, in a black display state, the transmittance sharply increases in a certain direction, so that the contrast ratio sharply decreases, and large viewing angle dependence occurs.

When an MLA is mounted on such a liquid crystal cell, the viewing angle dependency (the degree of change in the display state with respect to the viewing angle) can be greatly reduced, but the contrast when viewed from the front is reduced. FIG.
9 shows the viewing angle dependency of the contrast ratio before and after the MLA is mounted when the MLA shown in FIG. 2 is mounted on the observation surface of the liquid crystal cell having the characteristics shown in FIG. 9, and the viewing angle dependency is small. However, the front contrast ratio is low.

On the other hand, the liquid crystal display device of the present invention shown in FIG. 1 uses the same twisted nematic liquid crystal as the liquid crystal cell, but has an optically anisotropic layer having an optical axis in the normal direction of the display surface. A liquid crystal cell that satisfies the requirements of the present invention is used together with the above, and the MLA shown in FIG. 2 is mounted on the liquid crystal cell observation surface side.

As a result, as shown in FIG. 11, a decrease in the contrast ratio due to the mounting of the MLA is suppressed, and
The liquid crystal display device has a high image quality and a wide viewing angle while maintaining the viewing angle enlarging effect of the LA. FIG. 11 also shows the viewing angle dependence of the contrast ratio of the liquid crystal cell.

FIG. 1 shows a typical configuration of the liquid crystal display device of the present invention. A surface to be an observation surface of the liquid crystal display device of the present invention, for example, the surface 4 on the first material layer side in the MLA having the configuration shown in FIGS. 2 to 8, or an MLA 10 observation surface surface in the case of the configuration shown in FIG. For example, if necessary,
Antistatic treatment, surface hardening treatment (hard coat), as is done on the observation surface of conventional liquid crystal displays
And anti-reflection (anti-reflection) treatment and anti-glare (non-glare) treatment with an optical multilayer thin film.

Further, in order to make it easy to mount the MLA on the liquid crystal cell, the second material layer or the top of the convex portion of the first material layer penetrating the second material layer is formed of an adhesive or adhesive material. Alternatively, a material layer having tackiness or adhesiveness may be added to the surface of the second material or the top of the convex portion of the first material layer.

The substrate on which the MLA is formed can be selected according to the method of use, and is not essential.
The most versatile is a method using MLA based on glass or a transparent plastic film. In this case, it is preferable to use a transparent plastic film as the base material because it is easy to handle and the formation of the lens surface is relatively easy. In addition, MLA can be formed in a polarizing film mounted on a liquid crystal display. Especially,
In the case of a polarizing film having a structure in which a protective film is overlaid on a polarizer, using a protective film in which MLA has been formed in advance and using it as a polarizing film with MLA requires no additional steps in the conventional liquid crystal display manufacturing process. This is preferable in that a liquid crystal display equipped with the MLA of the present invention can be manufactured without addition.

The size and position of the unit lens of the MLA used in the present invention can be selected according to the size of the display unit of the liquid crystal cell, and two or more lenses correspond to one display unit. Is preferred. Thereby, ML
It is possible to suppress the occurrence of moire due to interference between the lens arrangement pitch of A and the display unit pitch of the cell. More preferably, four or more unit lenses correspond to one dot, and more preferably, eight or more unit lenses correspond to one display unit.

Here, the number n of unit lenses for one display unit is defined by the following equation (2) for a one-dimensional MLA and by the following equation (3) for a two-dimensional MLA.

N = N / (L / l) (2) n = N / (A / a) (3) where N is a unit lens on the effective display surface of the liquid crystal display device. L is the length of the liquid crystal cell in the one-dimensional MLA unit lens array direction, l is the length of one display unit of the liquid crystal cell that contributes to display in the lens array direction, A is the area of the LCD display surface, a is the area of a portion contributing to display in one display unit of the liquid crystal cell. These equations show the average number of lenses corresponding to the display unit portion excluding the portion that does not directly contribute to the display such as the wiring space on the LCD display surface.

When the liquid crystal display device of the present invention has a back light source, the back light source emits at least 80% of the total luminous flux emitted from the back light source within the effective viewing angle range of the liquid crystal cell when the back light source is provided. It is preferable to use

Here, the effective viewing angle range of the liquid crystal cell refers to a viewing angle range in which a good display quality is obtained when the liquid crystal cell is observed. Here, the maximum viewing angle range in the viewing direction in which the best display quality is obtained. Of the observation direction in which a contrast ratio of 1/5 is obtained with respect to the contrast ratio of.

There are two effects obtained by using a back light source having such directivity. One is that a light beam emitted from a light source such as a fluorescent tube can be used effectively. That is, in the liquid crystal display device of the present invention, the individual unit lenses of the lens array sheet refract the light flux transmitted in the direction in which the display quality of the liquid crystal cell is inferior, so that the observation is not affected and, at the same time, a good display is achieved. Since the luminous flux transmitted in the indicated direction can be observed from various directions, the back light source without directivity, which has been generally used conventionally, is emitted at a large angle with respect to the normal direction of the display surface. No luminous flux is used. Therefore, by giving directivity to the light beam emitted from the rear light source, the light beam emitted from the light source can be used effectively.

Further, another effect is that blurring of a displayed image can be prevented. In the liquid crystal display device of the present invention, a lens array sheet is mounted on an observation surface, and it is preferable that the lens array sheet is provided as close to the liquid crystal cell as possible. In general, there is a distance corresponding to the thickness of the substrate or the polarizing element for enclosing the liquid crystal between the concave and convex surfaces, so that it is often impossible to bring the liquid crystal sufficiently close. Therefore, the luminous flux transmitted through one display unit of the liquid crystal cell is
Not only the unit lens part corresponding to the display unit part,
The image reaches the unit lens at a slightly distant position, and the effect of the unit lens causes the outline of one display unit of the liquid crystal cell to be observed as blurred and enlarged, so that the displayed image is observed as blurred. On the other hand, when a directional back light source is used, even if there is some distance between the display unit portion of the liquid crystal layer and the uneven surface of the lens array sheet, the luminous flux transmitted through the display unit portion has directivity. Therefore, since the light reaches only the corresponding unit lens portion, the displayed image does not blur as described above. However, depending on the application of the liquid crystal display device, it may be preferable to blur the displayed image to some extent. In this case, it is possible to cope by controlling the directivity of the back light source.

In the case where the liquid crystal display device of the present invention is particularly required to suppress blurring of a displayed image, the light emission directivity of the back light source and the arrangement of display units in the direction of the lens unit in the unit of a small unit of display unit of the liquid crystal cell. It is preferable that the following relationship (4) is satisfied in the relationship of the pitch.

P ≧ dtan ・ ・ ・ (4) Here, p (mm) represents the length of the display unit of the liquid crystal cell in the direction of the minute unit lens arrangement, that is, the arrangement pitch of the display unit. However, when a liquid crystal cell forms one dot with a plurality of pixels for the purpose of performing color display or the like, one dot is used as a display unit. Further, d (mm) is the distance from the liquid crystal layer to the minute unit lens, and Δ is when a certain point on the back light source is inclined from the direction showing the maximum luminance to the minute unit lens arrangement direction. Represents an angle until the luminance becomes half of the maximum luminance.

In order to obtain a rear light source having such directivity, a light beam emitted from a light source such as a fluorescent tube is converted into a light using a means such as a Fresnel lens or a Fresnel prism, or a combination of a minute reflecting surface as a reflecting mirror. There is a means that uses a multi-reflector, a means that absorbs unnecessary light flux with an optical fiber sheet or a louver, etc., and is not limited to these. Among them, a point that effectively uses light emitted from a light source such as a fluorescent tube. It is preferable to provide a Fresnel sheet in which microlenses and microprisms are arranged in a sheet shape on the light-emitting surface close to the liquid crystal cell of the back light source because it is easy to reduce the thickness and weight.

[0053]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. (1) Preparation of a liquid crystal cell A twisted nematic liquid crystal TFT color display (screen diagonal 10.4 inches, pixel number 480 dots by width 640 dots, with backlight) mounted on a commercially available personal computer is a liquid crystal for a comparative example. Prepared as cell 1.

An optically anisotropic layer having an optical axis in the thickness direction in which the polarizing film mounted on the observation surface of the liquid crystal cell is once peeled off and the liquid crystal layer is held in a vertically aligned state between two glass plates. Then, the polarizing film was returned to the original state and bonded together to prepare a liquid crystal cell 2 used in Examples.

The viewing angle dependency of the liquid crystal cell 1 is shown in FIGS. 9 and 10, and the viewing angle dependency of the liquid crystal cell 2 is shown in FIG.

Table 1 shows the contrast ratio measured around the normal direction and the rate of change of the contrast ratio.

[0057]

[Table 1] (2) Preparation of MLA A mold in which a groove having a non-cylindrical side surface with a pattern pitch of 48 μm was dug was prepared, and a transparent ultraviolet-curable resin (refractive index after curing 1.48) was added thereto. A space was filled between the mold and a polyethylene terephthalate film (manufactured by Toray Industries, Inc.) having a coating thickness of 25 μm which had been subjected to an easy-adhesion treatment, and ultraviolet rays were irradiated from the film side to cure the ultraviolet curable resin.

A commercially available black resist containing carbon black (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the film surface of the obtained mold / ultraviolet effect resin layer / film laminate using a spin coater and dried. Ultraviolet light was exposed by a high-pressure mercury lamp through a photomask having a stripe pattern (pattern pitch: 48 μm), and an uncured portion was dissolved and removed by a developer.

At this time, a light-shielding layer having a width of 25 μm was formed by superimposing the alignment mark on the photomask with the mold so that the center line of the light-shielding layer coincided with the ridge line of the mold.

Next, the light-shielding layer side of the light-shielding layer / microlens composite obtained here was bonded to an acrylic flat plate (transparent plastic substrate) having a thickness of 0.8 mm to obtain the shape shown in FIGS. MLA was prepared.

(3) Preparation and Evaluation of Liquid Crystal Display Device The surfaces of the liquid crystal cells 1 and 2 obtained in (1) above, on which the lens irregularities of the MLA obtained in (2) were formed, were placed on the liquid crystal cell side and the light-shielding layer. The liquid crystal cell was mounted on the observation surface of the liquid crystal cell with the surface on which the was formed facing the observation surface. At this time, the mounting direction was the vertical direction of the screen in the arrangement direction of the unit lenses.

The front contrast ratio of the liquid crystal display devices 1 and 2 thus obtained in the vertical direction of the screen,
When the viewing angle dependence was evaluated, the liquid crystal display device 2 as the liquid crystal display device of the present invention obtained a front contrast ratio of 90 or more as shown in FIG.
%. In addition, a contrast ratio of 50 or more that can obtain a practical "clear" display in observation from virtually all directions was secured. On the other hand, the liquid crystal display device 1 has a front contrast ratio of about 4 as shown in FIG.
0, and the reduction rate was 70% or more.

Although there is no change in the viewing angle dependency in the horizontal direction of the screen due to the mounting of the MLA, the liquid crystal cell used here is a twisted nematic liquid crystal, and therefore has a wider viewing angle in the horizontal direction of the screen. Therefore, the liquid crystal display device of the present invention can observe good images from all directions.

As described above, the liquid crystal display device of the present invention
By finding that a slight difference in the characteristics of the liquid crystal cell is an important factor in a liquid crystal display device using MLA, it can be seen that the liquid crystal display device has an overwhelmingly high image quality and a wide viewing angle.

[0065]

According to the present invention, a liquid crystal display device having a wide viewing angle and high image quality can be obtained in a liquid crystal display device having an MLA mounted on an observation surface.

[Brief description of the drawings]

FIG. 1 schematically illustrates an example of the liquid crystal display device of the present invention.

FIG. 2 shows a one-dimensional MLA used in the liquid crystal display device of the present invention.
It is the schematic plan view which expanded one part of one example.

FIG. 3 is a view of the MLA shown in FIG.

FIG. 4 is a schematic plan view enlarging a part of an example of the MLA used in the liquid crystal display device of the present invention.

FIG. 5 is a view of the MLA shown in FIG.

FIG. 6 shows a two-dimensional MLA used in the liquid crystal display device of the present invention.
It is the schematic plan view which expanded one part of one example.

FIG. 7 is a cross-sectional view taken along line AA ′ of the MLA shown in FIG. 6;

FIG. 8 is a sketch drawing for explaining the shape of the MLA shown in FIGS. 6 and 7.

FIG. 9 is a diagram illustrating the viewing angle dependency of a conventional liquid crystal display device.

10 shows characteristics of a liquid crystal display device in which an MLA is mounted on a liquid crystal cell having the characteristics of FIG.

FIG. 11 shows characteristics of a liquid crystal display device of the present invention and characteristics of a liquid crystal cell used in the present invention.

[Explanation of symbols]

 1: First material layer of MLA 2: Second material layer of MLA 3: Uneven surface 4: Surface of first material layer 5: Surface of second material layer 6: Light shielding layer 7: Transparent plastic substrate 10: MLA 11: Upper polarizing plate 12: Optically anisotropic layer 13: Glass substrate of optically anisotropic layer 14: Liquid crystal layer for display 15: Glass substrate of liquid crystal layer for display 16: Lower polarizing plate 17: Louver sheet 18: Prism Sheet 19: Light guide plate 20: Fluorescent tube light source

Claims (1)

[Claims] 1. A liquid crystal cell, which is an array of liquid crystal light shutters for changing the alignment state of liquid crystal by applying an electric field or applying an electric current to an arbitrary display unit, and a liquid crystal cell having a liquid crystal shutter. A microlens array sheet configured by arranging the microunit lenses mounted on the observation surface in a planar manner, the microlens array sheet comprising: The angle dependency of the transmittance of the liquid crystal cell is controlled to be within 50% when expressed as a change ratio of a contrast ratio within a range of ± 15 degrees with respect to the normal direction of the display surface. Liquid crystal display.