JPH09197399A - Reflection plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reflect incident light at a prescribed angle with nearly a specified reflection intensity and to obtain such a reflection characteristic that hardly depends on the incident angle by providing a plane reflection surface and a reflection surface having a approximately spherical partial shape. SOLUTION: The reflection plate 701 is constituted by regularly and discretely disposing many reflection elements 702 having the approximately spherical partial shapes on a plane region 703. The reflection element 702 may have a convex surface or a concave surface. The surfaces of the reflection elements 701 may be formed by depositing a metal, such as aluminam by a sputtering method as to give a mirror surface reflection. Further, the reflection elements 702 may be formed by deposition of a metal, such as aluminum, by the sputtering method, etc., simultaneously with the formation of the surface of the reflection elements 702 if the occurrence of some mirroring-in is permitted in the part which is not arranged with the reflection elements of the flat planar region 703, that is, the plane region 703a remaining in the spacings between the reflection elements and the reflection elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector, and more particularly to a liquid crystal display device having a reflective electrode.

[0002]

2. Description of the Related Art In recent years, new display devices replacing conventional CRTs have been widely used, and liquid crystal display devices are one of them. The liquid crystal display device is a personal computer, word processor, EWS
OA display device, calculator, electronic book, electronic notebook, etc.
It is used in various fields such as display devices for PDAs and display devices for mobile TVs, mobile phones, portable facsimiles, and the like.

For such a display device, a display device with low power consumption is required because it is required to be driven by a battery, and the liquid crystal display device is widely used because it can be downsized, thinned, and operated with low power consumption. It has been put to practical use.

Since the liquid crystal itself is a non-emissive display element that does not emit light, the conventional liquid crystal display device is mainly of a transmissive type, that is, a flat illumination device called a backlight is provided on the back surface of the liquid crystal panel. . However, the backlight consumes a relatively large amount of power, which has been a major factor in hindering the low power operation which should be the original advantage of the liquid crystal display device.

A reflection type liquid crystal display device is a method in which a reflection plate for reflecting light is provided on the back surface of a liquid crystal panel and ambient light is reflected on the front surface to perform display. With this method, a backlight is not required, so that it is possible to significantly reduce power consumption.

However, in the conventional reflection type liquid crystal display device, since the transmittance of the liquid crystal portion is as low as several percent to several tens percent, it is difficult to obtain sufficient brightness only by reflecting the ambient light. On the other hand, if an attempt is made to increase the reflectance or the contrast ratio, the power consumption also increases, so bright paper white display cannot be performed, and vivid color display cannot be performed. Therefore, the reflective liquid crystal display device has not been put into practical use except for specific applications such as wristwatches and calculators.

However, in recent years, with the development of portable equipment, the need for a low power consumption display device has increased, and the need for a reflective liquid crystal display device has been reviewed. For example, as a display device of a portable device, a reflective liquid crystal display device that does not require a backlight and can be downsized, thinned, and operated with low power consumption is particularly suitable.

In the reflection type liquid crystal display device, its brightness, that is, the reflectance of the reflector is an important point. Since the light transmittance of liquid crystal is not high as described above, a high-performance reflector for obtaining a high reflectance is required to secure sufficient display quality.

When used in a liquid crystal display device, it is desirable that the reflection plate has a perfect diffuse reflection property as shown in FIG. 1 or FIGS. However, since the intensity of reflection is reduced by the complete diffuse reflection, there is a problem that sufficient brightness cannot be obtained due to the low transmittance of the liquid crystal as described above. To make up for this, see FIG.
Alternatively, as shown in FIGS. 4 and 102, a method of using a reflector having a property of strongly reflecting in a specific direction, that is, a directional reflector is conceivable. In this case, a stronger reflection than a perfect diffuse reflection can be obtained in a specific direction, but there is a drawback that the viewing angle becomes narrow.

Therefore, while ensuring a wide viewing angle,
The problem is to obtain a reflector having sufficient reflection intensity to compensate for the low transmittance of liquid crystal.

[0011]

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a reflector having a reflection characteristic such that incident light is reflected with a substantially constant reflection intensity over a predetermined angle range, and the range hardly depends on the incident angle of the incident light. .

It is another object of the present invention to provide a bright liquid crystal display device having a high display quality, which is provided with a reflection plate having such characteristics.

[0013]

The reflector of the present invention comprises a flat reflecting surface and a reflecting surface having a large number of substantially spherical partial shapes formed on the flat reflecting surface. And

Further, the reflecting plate of the present invention is characterized in that it has a planar region which is filled with a reflecting surface having a substantially spherical partial shape substantially without a gap.

The reflecting surface having a substantially spherical partial shape may be randomly arranged in a planar area.

The reflector of the present invention reflects parallel incident light as reflected light having a predetermined spread angle while maintaining substantially constant reflection intensity within a predetermined angle range smaller than this spread angle, and The spread angle is characterized by arranging a large number of reflecting surfaces in a planar region that does not substantially depend on the incident angle of the incident light.

Further, the reflecting plate of the present invention comprises a first reflecting surface having a flat surface and a second reflecting surface having a partial shape of a substantially spherical surface discretely formed on the first reflecting surface. It is characterized by having done. The second reflecting surface may be randomly distributed on the first reflecting surface.

The reflecting plate of the present invention includes a flat reflecting surface and a plurality of first reflecting areas formed on the flat reflecting surface for reflecting parallel incident light in the incident direction within a first intensity range. A reflection element having a second reflection region that reflects the incident light in the incident direction in a second intensity range smaller than the first intensity range.

The liquid crystal display device of the present invention is characterized by including a reflection plate in which a large number of reflection elements having a substantially spherical partial shape are arranged in a planar region. You may make it form a reflecting surface in this planar area.

The liquid crystal display device of the present invention comprises a reflector having a planar region substantially filled with reflecting elements having a plurality of substantially spherical partial shapes randomly arranged. Reflective liquid crystal display device.

The liquid crystal display device of the present invention is provided with, as a reflective electrode, a reflective plate having a planar region substantially filled with a plurality of randomly arranged reflective elements having a substantially spherical partial shape. It is characterized by

That is, the reflector of the present invention reflects the incident light with a substantially constant reflection intensity over a predetermined angle range, and in order to obtain a reflection characteristic such that the range hardly depends on the incident angle of the incident light, A large number of reflective elements, each of which is a reflective surface having a substantially spherical shape, are formed in a planar region.

FIG. 1 is a diagram schematically showing the reflection characteristics of a perfect diffuse reflection surface.

The perfect diffuse reflection surface has good viewing angle characteristics, but the intensity of the reflected light with respect to the incident light becomes weak. Therefore, for example, when it is used as a reflection plate of a reflection type liquid crystal display device, the reflection intensity is weak and it is insufficient to compensate for the low light transmittance of the liquid crystal.

In order to increase the reflection intensity, the directivity of the reflected light may be strengthened. However, if the directivity of the reflected light is increased, the viewing angle characteristic will be deteriorated. FIG. 2 is a diagram schematically showing the reflection characteristics of a reflecting surface that causes specular reflection.

For example, on a total reflection surface such as a flat mirror surface, the incident light is almost totally reflected, so that the intensity of the reflected light can be concentrated in a specific direction to obtain a sufficient reflection intensity, but the viewing angle characteristic is narrow. Become. That is, the reflection intensity of the incident light abruptly declines if it deviates slightly from the reflection direction (see FIG. 4).

The reflecting plate of the present invention has a plurality of reflecting surfaces each having a substantially spherical partial shape in a planar region in order to obtain a reflecting surface having both sufficient reflection strength and viewing angle characteristics. Is.

FIG. 3 is a diagram schematically showing a reflection characteristic of a reflecting surface having a partial spherical shape as an example of the reflecting surface having a substantially spherical partial shape. It can be seen that this reflecting surface has good reflection strength and viewing angle characteristics. That is, it has a reflection characteristic such that the incident light is reflected with a substantially constant reflection intensity over a predetermined angle range, and that the range hardly depends on the incident angle of the incident light. Such reflection characteristics are the same whether the concave surface side or the convex surface side of the spherical surface is used.

FIG. 4 is a diagram schematically showing the relationship between the range of the spread angle of the reflected light with respect to the incident light and the reflection intensity of these reflecting surfaces. 101 indicates the case of diffuse reflection and 10
2 shows the case of specular reflection, and 103 shows the case of spherical reflection.

FIGS. 5 and 6 are views showing a state where the reflection characteristics shown in FIG. 4 are preserved over a predetermined incident angle in the case of a reflecting surface having a spherical partial shape.

That is, the reflecting element having a substantially spherical partial shape formed on the reflecting plate of the present invention reflects parallel incident light with a substantially constant reflection intensity over a predetermined spread angle, and this angle range is incident. It is characterized by having a reflection characteristic that is substantially independent of the incident angle of light. The reflection plate of the present invention is characterized in that a large number of reflection elements having such reflection characteristics are arranged in a predetermined arrangement on the reflection plate as described later.

Compared with a reflecting surface that causes diffuse reflection, the reflecting element having a substantially spherical shape keeps a predetermined reflection intensity by limiting the angular range of the spread of the reflected light with respect to the incident light. On the other hand, as compared with a reflection surface that causes specular reflection, the reflection surface is improved by weakening the reflection intensity and increasing the spread angle of the reflected light with respect to the incident light.

Therefore, the reflection plate of the present invention realizes good reflection characteristics that secure a constant viewing angle and reflection intensity by using a reflection element having a substantially spherical partial shape.

Basically, if a large number of reflective elements are arranged in a plane area, the same reflective characteristics are preserved over the entire display surface if they are formed in similar shapes. It is not necessary that the reflecting surfaces of the partial shapes of the respective substantially spherical surfaces have the same shape, and it is sufficient that they have similar shapes in general.

As the approximately spherical surface, an approximately quadric surface may be used. For example, an ellipsoidal surface (oblong spherical surface / oblique spherical surface), elliptical surface of revolution, hyperboloidal surface, hyperbolic surface of revolution, paraboloid, parabolic surface of revolution, etc. May be used, or a curved surface shape formed by a combination of these may be used.

The curved concave surface may be used, or the convex surface may be used.

The arrangement of these reflective elements in a planar area will be described below.

The reflecting plate of the present invention comprises a plurality of reflecting elements, each of which has a partially spherical shape having the above-mentioned reflection characteristic, arranged in a planar region.

Regarding the arrangement, a large number of reflecting elements are arranged in a plane area, and the ratio of the plane reflecting surface to the reflecting element is
The shape of the reflective elements to be formed in the planar area, whether the reflective elements are regularly arranged or irregularly arranged (including multidimensional regularity and irregularity) are determined as necessary. It should be designed as follows.

For example, the reflecting elements may be arranged regularly and discretely in a planar area, or may be arranged so as to be the closest packing arrangement. When arranged in this way, a planar reflection surface remains between the reflection elements, so if a reflection surface that causes specular reflection is formed in this part, the background reflection Cause When this reflection is an obstacle, a diffuse reflection surface may be formed on the flat reflection surface. Further, an approximately spherical reflecting element may be further formed so as to fill the remaining planar reflecting surface.

If the reflecting elements are regularly arranged, for example, in the closest packing arrangement, light interference occurs due to the arrangement regularity. If it is desired to avoid this interference, the reflective elements may be randomly arranged. Further, even in the case of regular arrangement, the shape of each reflective element may be slightly different (in this case, the arrangement is close to the closest packing arrangement). Further, the random arrangement of the reflecting elements may be varied not only in the plane direction but also in the axial direction perpendicular to the plane area.

Further, the reflecting elements may be formed randomly and discretely to avoid interference. In this case, since a flat reflecting surface remains, a diffuse reflecting surface is formed on this flat reflecting surface. You may do it. By arranging in this way, it becomes a reflection plate that does not cause reflection or interference.

Further, the reflecting elements may be arranged at random so as to have overlapping portions so as to cover the planar area without a gap. Even if it is arranged in this way, it becomes a reflector that does not cause reflection or interference.

According to the present invention, in a reflection plate used in a reflection type liquid crystal display device, a gap is filled in a planar region in which a plurality of convex or concave shapes having a partial shape of an approximately spherical surface are discretely formed. It has a convex or concave aggregate shape formed by stacking convex or concave shapes, and a reflective film is formed thereon.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 is a diagram schematically showing a part of the reflection plate of the present invention. The reflecting plate 701 includes a large number of reflecting elements 702 having a substantially spherical partial shape, which are regularly and discretely arranged in a planar region 703. The reflective element 702 may have a convex shape or a concave shape. The surface of the reflection element 702 may be formed by depositing a metal such as aluminum by a sputtering method or the like so as to cause specular reflection.

In the flat area 703 where the reflective element is not arranged, that is, in the flat area 703a remaining in the gap between the reflective elements, when some reflection may occur, the reflection is performed. At the same time when the surface of the element 702 is formed, a metal such as aluminum may be deposited by a sputtering method or the like. As described above, the planar region 70 is included in the reflection by the reflection element 702 having a partial shape of a substantially spherical surface.
When the contribution of the specular reflection by 3a is added, the reflection characteristic of the reflection plate 701 has a strong reflection component 704 in the front direction as schematically shown in FIG. 8 (see FIG. 3).

In the plane area 703a formed in the gap of the reflection element 702, a reflection surface that causes diffuse reflection may be formed. If the diffuse reflection surface is formed, the viewing angle characteristics are improved and the background is not reflected. The diffuse reflection surface may be chemically treated, for example, by treating the aluminum reflection surface formed by the sputtering method with an acid, or the surface may be roughened by implanting ions. Further, an abrasive material is used. Alternatively, it may be formed by physically processing such as polishing.

9 and 10 show the reflector plate 70 illustrated in FIG.
It is a figure which shows the cross section of 1 roughly. 9 shows the case where the convex reflection element 702a is used, and FIG. 10 shows the concave reflection element 70.
The case where 2b is used is shown. As described above, in the reflector of the present invention, the convex surface of the reflective element may be used, or the concave surface may be used.

11 and 12 are schematic views showing a part of another example of the reflector of the present invention. This reflection plate 11
Reference numeral 01 denotes a reflective element 1102 having a partially spherical shape, which is arranged in a planar region 1103 so as to be closest packed.

13 and 14 are schematic views showing the cross section of the reflector shown in FIG. 11 or FIG. FIG. 13 shows the case where the convex reflection element 1102a is used, and FIG. 14 shows the case where the concave reflection element 1102b is used.

A planar area 1103a remaining between the reflecting elements
In addition, a diffuse reflection surface may be formed similarly to the reflection plate illustrated in FIG. 7, or a specular reflection surface may be formed. Even when the specular reflection surface is formed, when the reflection elements 1102 are densely arranged, the proportion of the planar area is reduced, and thus the reflection is reduced.

FIG. 15 is a diagram schematically showing still another example of the reflection plate of the present invention. The reflection plates 1501 are mutually reflective elements 1502 so as to fill a region 1503a of a gap between the reflection elements 1502a having a substantially spherical partial shape.
It is formed so that b overlaps. In this way, if the planar region is covered with substantially no gap so that the reflective element 1502 having the substantially spherical partial shape intersects with the other reflective element 1502 having the substantially spherical partial shape, the There is no reflection.

16 and 17 are schematic views showing still another example of the reflector of the present invention. These reflectors 16
01 is the reflection element 1 like the reflection plate illustrated in FIG.
The reflective elements 1602b are formed so as to overlap each other so as to fill the region 1603a in the gap between the 602a.

As illustrated in FIG. 17, typical reflective elements 1602b having different diameters may be formed so as to fill the gap area 1603a of the reflective element 1602a. By the way, if the reflective elements are regularly arranged as described above, interference of reflected light occurs. In order to avoid this interference, the reflective elements may be randomly arranged in a planar area. Random placement is 2 within a planar area.
It may be arranged randomly in a dimension, or the height (depth) of the reflective element may be randomized,
Further, these may be combined. Also,
The shape of each reflecting element, that is, the shape of the reflecting surface having a substantially spherical shape may be randomly formed.

FIG. 18 is a view schematically showing still another example of the reflection plate of the present invention. In this reflection plate 1801, reflection elements 1803 each having a substantially spherical partial shape are randomly arranged in a planar area 1802. Similar to the reflection plate described so far, the reflective element may have a convex shape or a concave shape. A metal such as aluminum may be deposited by a sputtering method or the like so that the surface of the reflective element causes specular reflection. Further, a diffuse reflection surface or a specular reflection surface may be formed in the area between the reflection elements.

19 to 22 are views showing cross sections of the reflection plate illustrated in FIG.

FIG. 19 is a view showing a state in which convex reflection elements 1803a are randomly arranged two-dimensionally.
0 is a diagram showing a state in which concave reflection elements 1803b are randomly arranged two-dimensionally.

FIG. 21 is a view showing a state in which convex reflection elements 1803a are three-dimensionally randomly arranged.
2 is a diagram showing a state where concave reflection elements 1803b are three-dimensionally arranged at random.

A gap area 1802 between the reflecting elements 1802
If a diffuse reflection surface is formed on a, no reflection occurs, and since the reflection elements 1803 are randomly arranged, interference is not generated and the reflection plate has excellent characteristics.

FIG. 23 is a view schematically showing still another example of the reflection plate of the present invention. The reflecting plate 2301 covers the planar area 2303 randomly and substantially without covering the planar area 2303 so that the reflective element 2302 having a substantially spherical partial shape overlaps with other reflective elements. It is arranged in.

24 and 25 are schematic views showing the cross section of the reflection plate illustrated in FIG. FIG. 24 shows the case where a convex reflection element 2302a is used, and FIG. 14 shows the case where a concave reflection element 2302b is used.

As described above, the reflector having the planar region 2303 substantially filled with the aggregate of the reflective elements 2302 having the substantially spherical partial shape has good viewing angle characteristics and sufficient reflection intensity. It is a reflector that has both the characteristics and the characteristics that neither reflection nor interference occurs.

Next, one example of the method for manufacturing the reflector of the present invention will be described with reference to the drawings. Here, a manufacturing method of a reflecting plate, in which planar regions are substantially filled with randomly arranged reflecting elements, will be described as an example.

First, a photosensitive acrylic resin 2602 such as ΗRC-104 (manufactured by Japan Synthetic Rubber, trade name) is spin-coated to a thickness of about 2 μm on a substrate 2601 such as glass (FIG. 26). Here, the thickness is about 2 μm, but the thickness may be set as necessary.

After that, the glass substrate 2601 on which the photosensitive acrylic resin 2602 is spin-coated is baked at about 80.degree.

Then, the diameter is reduced to about 1 by mask exposure and development.
A large number of 0 μm convex patterns 2603 are formed in a random arrangement (FIG. 27). The diameter of the convex pattern is
You may make it form a typical diameter to about 10-30 micrometers. Moreover, the diameter of each pattern does not need to be the same.

After that, the substrate on which the convex pattern 2603 was formed was baked at about 200.degree. As a result, the acrylic resin of the convex pattern 2603 exhibits fluidity, and the formed convex pattern 2603 part has a substantially spherical partial shape 2604 and solidifies, loses photosensitivity, and is resistant to ultraviolet light and a developing solution. Stable (Fig. 28).

Next, a photosensitive acrylic resin 2602b was further spin-coated to a thickness of about 2 μm on a large number of aggregate patterns 2604 having a substantially spherical partial shape formed as described above, and baked at about 80 ° C. ( 29).

Then, a convex pattern 2603b was formed by mask exposure and development so as to cover the gap of the partial shape 2604 of the approximately spherical surface that was initially formed (FIG. 30).

This substrate was baked at about 200.degree.
As a result, the acrylic resin of the convex pattern 2603b exhibits fluidity, and the formed convex pattern portion has a substantially spherical partial shape 2604b and solidifies, loses photosensitivity, and is resistant to ultraviolet light and a developing solution. Stable (Figure 31).

A partial shape 2604 of a substantially spherical surface formed later.
The shape of b is a partial shape 2604 of the approximately spherical surface formed first.
The shape may be the same as the shape of a or may be different.

On the thus obtained aggregate pattern 2605 having a partially spherical shape, aluminum was deposited by sputtering to a thickness of about 4000 angstroms to form a reflecting surface 2606 that causes specular reflection (see FIG. 32). The surface of the reflective element is not limited to the sputtering method, but may be formed by, for example, an electroless plating method. The metal used is not limited to aluminum.

Through these steps, the reflecting plate composed of the planar region substantially filled with the aggregate of the reflecting elements having the shape of a part of the substantially spherical surface was formed.

If the plane of the gap between the reflecting elements is substantially filled with the reflecting elements, the specular reflection due to the flat portion between the reflecting elements is sufficiently small, and as a result, good reflection characteristics can be obtained. If it is desired to further reduce the area of the plane portion, the above-mentioned photosensitive acrylic resin may be further applied onto the assembly of these reflective elements, and the reflective elements may be formed so as to cover the gap, Further, a diffuse reflection surface may be formed in the plane area.

The formation of the convex reflecting element is not limited to the resin that has fluidity by heating, and any desired reflecting element shape may be obtained.

FIG. 33 is a diagram schematically showing the reflection characteristics of the reflector of the present invention illustrated in FIG. The figure shows the case where the incident angle of incident light with respect to the reflector is 0 and 45 degrees. It can be seen that in both cases, the incident light is strongly reflected to the front and has a substantially constant reflection intensity in a certain visual field range.

Next, a method of manufacturing a reflection plate using the concave surface of the reflection element having an approximately spherical surface will be described.

First, a photosensitive acrylic resin 3402 such as ΗRC-104 (manufactured by Japan Synthetic Rubber, trade name) is spin-coated to a thickness of about 2 μm on a substrate 3401 such as glass (FIG. 34). Here, the thickness is about 2 μm, but the thickness may be set as necessary.

Thereafter, the glass substrate spin-coated with the photosensitive acrylic resin is baked at about 80 ° C.

Then, the mask is exposed and developed to have a diameter of about 1
A large number of 0 μm concave patterns 3403 are formed in a random arrangement (FIG. 35). The diameter of the concave pattern is
You may make it form a typical diameter to about 10-30 micrometers. Moreover, the diameter of each pattern does not need to be the same.

After that, the substrate on which the concave pattern 3403 was formed was baked at about 200.degree. As a result, the acrylic resin exhibited fluidity, and the formed concave pattern portion had a spherical partial shape 3404 and solidified, lost the photosensitivity, and was stable to ultraviolet light and a developing solution (FIG. 36).

Next, a photosensitive acrylic resin 3402b was further spin-coated to a thickness of about 2 μm on the aggregate pattern of a large number of substantially spherical partial shapes 3404 formed as described above, and baked at about 80 ° C. ( Figure 37). At this time, by adjusting the viscosity of the acrylic resin, the resin could be applied while leaving the shape 3404b in which the partial shape 3404 of the generally spherical surface that was initially formed was retained.

Then, by mask exposure and development, a concave pattern 3403c is formed so as to cover the gap of the partial shape 3404b of the formed roughly spherical surface (FIG. 38).

After that, the substrate having the concave pattern 3403c formed thereon was baked at about 200.degree. as a result,
The acrylic resin exhibited fluidity, and the formed concave pattern portion had a shape 3404c of a substantially spherical surface and solidified, lost the photosensitivity, and was stable to ultraviolet light and a developing solution (FIG. 39). The shape 34 of a part of the substantially spherical surface formed later
04c is a shape 3404 of a part of the approximately spherical surface formed first.
It may have the same size as b or may have a different size. Further, the diameter and depth of a part of the shapes of the approximately spherical surfaces do not have to be the same, and the concave opening surface does not have to be in the same plane.

Aluminum was deposited by a sputtering method to a thickness of about 4000 angstroms on the obtained aggregate pattern of a partial shape of the spherical surface to form a reflecting surface (FIG. 4).
0). Through these steps, the reflection plate 3405 including the planar region substantially filled with the aggregate of the reflection elements having a partial shape of the approximately spherical surface was formed (see FIG. 48).

If the plane of the gap between the reflecting elements is substantially filled with the reflecting elements, the specular reflection due to the flat portion will be sufficiently small, and as a result, good reflection characteristics will be obtained. If it is desired to further reduce the area of the plane portion, the above-mentioned photosensitive acrylic resin may be further applied onto the assembly of these reflective elements, and the reflective elements may be formed so as to cover the gap, Further, a diffuse reflection surface may be formed in the plane area.

The formation of the convex reflecting element is not limited to the resin having fluidity by heating, and any desired reflecting element shape may be obtained.

The reflection characteristics of the reflector of the present invention illustrated in FIG. 40 are similar to those of the reflector illustrated in FIG. That is, it can be seen that the incident light is strongly reflected to the front and has a substantially constant reflection intensity in a certain visual field range.

FIG. 41 is a sectional view schematically showing the structure of the liquid crystal display device of the present invention.

This liquid crystal display device 4100 has the reflective electrode 4
As the reference numeral 102, for example, a reflection plate having a substantially spherical partial shape as shown in FIG. 23 is randomly arranged in a planar region. The reflective electrode 4102 is connected to the drain electrode 4105 of the thin film transistor 4104 via the contact hole 4103.

Then, the array substrate 4101 on which the reflective electrode 4102 is formed and the transparent electrode 410 such as ITO.
A liquid crystal is sandwiched between the counter substrate 4107 and the counter substrate 4107.

On the array substrate 4101, in addition to the thin film transistors 4104, although not shown, signal lines, gate lines and auxiliary capacitance lines corresponding to the respective pixels are formed.

Although the inverse stagger type thin film transistor 4104 is used as the non-linear element here, other types of thin film transistors such as a forward / reverse stagger type thin film transistor may be used. Also, for example, MIM
Non-linearities other than thin film transistors such as elements may be used.

Next, an example of a method of forming the reflective electrode 4102 will be shown. An insulating layer made of a photosensitive acrylic resin is applied on the array substrate 4101 to form concave (convex) surfaces having spherical partial shapes overlapping each other as illustrated in FIGS. 26 to 32 or 34 to 40. Here, the exposure for forming the contact hole for connecting the reflective electrode and the thin film transistor was performed prior to the concave or convex exposure.

After that, a reflecting surface made of aluminum was formed by sputtering so as to cover the acrylic resin having a large number of spherical partial shapes, and the reflecting electrode 4102 was patterned by etching.

The reflective electrode 4102 thus obtained
The reflection-type liquid crystal display device having the above has a strong reflection component in a predetermined range near the front reflecting the reflection characteristics of the reflection electrode 4102, and as a result, a bright reflection-type liquid crystal display device was obtained. The reflection characteristic of the reflective electrode 4102 is adjusted by changing the size of the unevenness of the partial shape of the approximately spherical surface formed on the electrode, specifically, by changing the ratio of the diameter and the height (depth) of the partial shape of the approximately spherical surface. You may do it. If the radius of curvature of the reflecting surface is large, that is, if the reflecting surface is close to a flat surface, the reflection characteristic becomes close to specular reflection.

As described above, this liquid crystal display device is provided with a reflector having an excellent characteristic of having a wide viewing angle characteristic and a sufficient reflection intensity, so that a bright, high-contrast and high-quality screen display can be displayed in the ambient light. Is achieved with low power consumption. It is particularly suitable as a display device for portable information equipment.

Next, another method of manufacturing the reflector of the present invention will be described.
An example will be described.

First, a base material 420 such as a glass substrate.
A binder 4203 made of a thermosetting resin such as an epoxy resin or an acrylic resin in which the spherical particles 4202 are dispersed is applied onto 1 and then heated to cure the binder 4203. The spherical particles 4202 may be made of silica, for example. Typical diameter of spherical particles 4202 is 1
The particle size may be distributed in the range of about 0 to 30 μm, or may be normally distributed around a certain value of 10 to 30 μm.

After curing, the binder 4203 contracts and the base material 4
The surface of 201 was solidified with the surface of the spherical particles 4202 partially exposed (FIG. 42).

Next, the stretched silicone rubber 4204 was pressure-bonded to the surface of the binder 4203 in which the spherical particles 4202 were dispersed, and left at room temperature (FIG. 43).

Then, with the silicone rubber 4204 hardened to some extent, the silicone rubber 4204 is replaced with the binder 42.
No. 03 (Fig. 44), and the silicon rubber 4204 and the spherical particles 4 are again placed at the position displaced from the first pressure-bonded state.
A binder 4203 in which 202 was dispersed was pressure-bonded and left at room temperature (FIG. 45). When shifting from the first pressure-bonded state, they may be moved in parallel, may be rotated, or they may be combined.

Through these steps, the silicone rubber 420
On the surface of No. 4, a large number of concave concave surface aggregate shapes 4205 were formed so as to intersect with other spherical concave surfaces. (Fig. 46). The step of shifting the silicon rubber and re-compression bonding may be repeated several times.

Using the silicone rubber on which the concave aggregate shape 4205 is formed as a mold, the pattern of the concave aggregate shape 4205 is transferred to the resin surface such as acrylic resin to form the convex aggregate shape 4206. (Fig. 4
7).

The convex aggregate shape 420 thus obtained
By depositing a metal thin film of aluminum or the like on No. 6 by, for example, a sputtering method, a reflecting plate was obtained in which partial shapes of substantially spherical surfaces overlap each other and substantially fill a planar area (FIG. 47). .

It is possible to form a convex silicon mold and a concave reflector by the same method (FIG. 48).

An example of a method of manufacturing a reflector of a liquid crystal display device using such a die will be described.

First, for example, a photosensitive acrylic resin 4904 is spin-coated to a thickness of about 2 μm on an array substrate 4903 in which a non-linear element such as a thin film transistor 4902 and wiring (not shown) are formed on an insulating substrate 4901 such as glass. (Fig. 49). The thickness may be set as needed.

After masking the contact hole portion, for example, a pressing die having an aggregated shape of concave surfaces formed so that the spherical concave surfaces as illustrated in FIG. 46 intersect with other spherical concave surfaces is pressure-bonded to the acrylic resin. Then, the shape of the stamp was transferred to the acrylic resin.

After that, a contact hole with a thin film transistor was formed by photolithography, and baking was further performed. As a result, the acrylic resin was cured, lost its photosensitivity, and was stable to ultraviolet light and a developing solution.

It is not necessary to use the fluidity of the surface during baking to smooth the shape of the acrylic resin surface. Also, the surface fluidity could be suppressed by baking at a low temperature of about 170 ° C.

Aluminum was deposited by a sputtering method to a thickness of about 4000 angstroms on the thus-obtained aggregate having a plurality of spherical partial shapes (convex shapes) to form a reflecting surface 4905 (FIG. 50).

If the liquid crystal layer is sandwiched between the array substrate 4903 having the reflection plate 4905 and the counter substrate having the counter electrode, the liquid crystal device as shown in FIG. 41 is obtained.

Further, a liquid crystal display device provided with a concave reflection plate can be manufactured by the same method. FIG. 51 shows an example of such a liquid crystal display device.

In the manufacturing example of the reflection type liquid crystal display device described here, since the method of transferring the pressing shape is used, a large number of reflection plates (reflection electrodes) can be repeatedly manufactured,
It is also effective in reducing the manufacturing cost of the reflector.

Next, a method of forming an aggregate of a partial shape of a roughly spherical surface by another method will be described.

Appl.Phys.Let.52 (10), 7 March 1988 S
There is a description about a method of forming a concave surface having a shape of a spherical surface on an i substrate. This is to form pyramid-shaped pits on the surface of the Si substrate by different-direction etching using KOH (potassium hydroxide), and then to etch with KOH for several hours, whereby the pits become spherical concave surfaces.

Therefore, as shown in FIG.
An etching mask (not shown) was formed on the surface of the substrate 5201 using a silicon thermal oxide film, and the pit 5202 was formed by etching with a KOH aqueous solution. The depth of the pit 5202 was set to be 5 to 10 μm. The pits were randomly arranged on the plane. The size of the pits may also be formed randomly.

After removing the etching mask, etching was further performed in a KOH aqueous solution (40 wt%, 70 ° C.) for 2 to 7 hours. As a result, a concave aggregate 5203 having a large number of substantially spherical partial shapes as shown in FIG. 52B was formed.

Silicon rubber was pressure-bonded to the obtained Si substrate and left at room temperature to form a die. By using the die obtained in this way, it is possible to manufacture a reflection plate composed of an aggregate of partial shapes of substantially spherical surfaces by the same method as described above.

As described above, it is possible to form the aggregate of the substantially spherical partial shapes by various methods, and it is also possible to form it by a method other than the method described above. For example,
By stirring and decompressing a resin such as petropoxy, fine bubbles with a typical diameter of about 10 to 30 μm are formed in the resin, and solidified as it is to form an aggregate of partial spherical partial shapes. Good.

In the manufacturing example of the reflecting plate described above, the manufacturing method of the reflecting plate in which the reflecting elements are arranged randomly and overlapping with each other to fill the planar area is explained. It is possible to manufacture the reflection plate having the other reflection element arrangement described above in the same manner.

The reflection characteristic of the reflection electrode is obtained by changing the size of the irregularities of the partial shape of the general spherical surface formed on the electrode, specifically, the ratio of the diameter and the height (depth) of the partial shape of the general spherical surface. It may be adjusted with.

[0125]

As described above, the reflector of the present invention is
Parallel incident light is reflected as reflected light having a predetermined divergence angle within a predetermined angular range smaller than this divergence angle while maintaining a substantially constant reflection intensity, and the divergence angle of the reflected light is equal to the incident angle of the incident light. By arranging a large number of reflecting surfaces that are substantially independent of each other in a planar region, the reflecting plate has both excellent viewing angle characteristics and sufficient reflection strength and excellent reflection characteristics.

Further, since the liquid crystal display device of the present invention is provided with the reflecting plate having excellent characteristics, it is possible to realize a wide viewing angle, a bright and high-contrast screen display by utilizing ambient light. In particular, when the liquid crystal display device of the present invention is used for the display device of a portable information device, the display device has both low power consumption and high display quality.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a reflection characteristic of diffuse reflection.

FIG. 2 is a diagram schematically showing a reflection characteristic of specular reflection.

FIG. 3 is a diagram schematically showing the reflection characteristics of a spherical mirror surface.

FIG. 4 is a diagram schematically showing a relationship between a range of a spread angle of reflected light and reflection intensity.

FIG. 5 is a diagram schematically showing the reflection characteristics of a spherical mirror surface.

FIG. 6 is a diagram schematically showing the reflection characteristics of a spherical mirror surface.

FIG. 7 is a diagram schematically showing a part of a reflector of the present invention.

FIG. 8 is a diagram schematically showing an example of the reflection characteristics of the reflection plate of the present invention.

9 is a view showing a cross section in the AB direction of the reflection plate illustrated in FIG.

10 is a diagram showing a cross section in the AB direction of the reflection plate illustrated in FIG. 7. FIG.

FIG. 11 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 12 is a diagram schematically showing a part of a reflection plate of the present invention.

13 is a view showing a cross section in the CD direction of the reflection plate illustrated in FIG.

14 is a diagram showing a cross section in the CD direction of the reflection plate illustrated in FIG. 12;

FIG. 15 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 16 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 17 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 18 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 19 is a diagram showing a cross section in the EF direction of the reflection plate illustrated in FIG. 18;

20 is a view showing a cross section in the EF direction of the reflection plate illustrated in FIG. 18;

FIG. 21 is a diagram showing a cross section in the EF direction of the reflection plate illustrated in FIG. 18;

22 is a diagram showing a cross section in the EF direction of the reflector illustrated in FIG.

FIG. 23 is a diagram schematically showing a part of a reflection plate of the present invention.

FIG. 24 is a diagram schematically showing a cross section of the reflection plate illustrated in FIG. 23.

FIG. 25 is a diagram schematically showing a cross section of the reflector illustrated in FIG. 23.

FIG. 26 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 27 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 28 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 29 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 30 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 31 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 32 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 33 is a diagram schematically showing the reflection characteristics of the reflection plate illustrated in FIG. 32.

FIG. 34 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 35 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 36 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 37 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 38 is a diagram schematically showing an example of the manufacturing method of the reflecting plate of the present invention.

FIG. 39 is a diagram schematically showing an example of a method for manufacturing a reflecting plate of the present invention.

FIG. 40 is a diagram schematically showing an example of a method for manufacturing a reflection plate of the present invention.

FIG. 41 is a diagram schematically showing a liquid crystal display device of the present invention.

FIG. 42 is a diagram schematically showing another example of the manufacturing method for the reflector of the present invention.

FIG. 43 is a view schematically showing another example of the manufacturing method for the reflector of the present invention.

FIG. 44 is a diagram schematically showing another example of the method for manufacturing a reflecting plate of the present invention.

FIG. 45 is a diagram schematically showing another example of the method for manufacturing a reflecting plate of the present invention.

FIG. 46 is a diagram schematically showing another example of the manufacturing method for the reflector of the present invention.

FIG. 47 is a view schematically showing another example of the manufacturing method of the reflecting plate of the present invention.

FIG. 48 is a diagram schematically showing another example of the manufacturing method for the reflecting plate of the present invention.

FIG. 49 is a diagram schematically showing an example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 50 is a diagram schematically showing an example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 51 is a diagram schematically showing an example of a method for manufacturing a liquid crystal display device of the present invention.

FIG. 52 is a view schematically showing another example of the manufacturing method of the reflecting plate of the present invention.

[Explanation of symbols]

101 ... Diffuse reflection surface reflection characteristics, 102 ... Specular reflection surface reflection characteristics 103 ... Reflection characteristics of reflection plate of the present invention 701 ... Reflection plate, 702 ... Reflection element, 702a.
Reflective element (convex type) 702b ... Reflective element (concave type), 703 ... Planar area 703a ... Planar area (gap), 704 ... Specular reflection component 1101 ... Reflective plate, 1102 ... Reflective element 1102
a ... Reflective element (convex type) 1102b ... Reflective element (concave type) 1103 ... Planar area 1103a ... Planar area (gap) 1501 ... Reflector plate, 1502a ... Reflective element, 150
2b ... Reflecting element 1503 ... planar area, 1503a ... planar area (gap) 1601 ... reflecting plate, 1602a ... reflecting element, 160
2b ... Reflective element 1603 ... Planar region, 1603a ... Planar region (gap) 1801 ... Reflector, 1802 ... Planar region 1802a ... Planar region (gap), 1803 ... Reflective element 1803a ... Reflective element (convex type), 1803b ... Reflective element (concave type) 2301 ... Reflective plate, 2302 ... Reflective element, 2303
...... Planar region 2601 ...... Glass substrate, 2602 ...... Photosensitive acrylic resin 2603 ...... Convex pattern, 2604 ...... Partial shape of general spherical surface 2605 ...... Assembly pattern of partial shape of general spherical surface, 26
06 ... Reflecting surface 3401 ... Glass substrate, 3402 ... Photosensitive acrylic resin 3403 ... Concave pattern, 3404 ... Partial shape of approximately spherical surface 4100 ... Liquid crystal display device, 4101 ......... Array substrate, 4102 ... Reflective electrode 4103 ... Contact hole, 4104 ... Thin film transistor 4105 ... Drain electrode, 4106 ... Transparent electrode, 4
107 ... Counter substrate 4201 ... Substrate 4202 ... Spherical particles 4203 ...
... Binder 4204 ... Silicon rubber, 4205 ... Concave surface aggregate shape 4206 ... Convex surface aggregate shape 4901 ... Insulating substrate, 4902 ... Thin film transistor 4903 ... Array substrate, 4904 ... Photosensitive acrylic resin 4905 ... … Reflector 5201 …… Si substrate, 5202 …… Pit, 5203
...... Concave surface shape

Claims (5)

[Claims] 1. A reflecting plate comprising a flat reflecting surface and a reflecting surface having a large number of substantially spherical partial shapes formed on the flat reflecting surface. 2. A reflection plate comprising a planar region which is filled with a reflection surface having a substantially spherical partial shape substantially without a gap. 3. The reflection plate according to claim 1, wherein the reflection surface having the partial shape of the substantially spherical surface is randomly arranged in the planar region. 4. The parallel incident light is reflected as reflected light having a predetermined spread angle while maintaining a substantially constant reflection intensity within a predetermined angle range smaller than the spread angle, and the spread angle of the reflected light is A reflecting plate, wherein a large number of reflecting surfaces substantially independent of the incident angle of the incident light are arranged in a planar area. 5. A liquid crystal display device, comprising: a reflection plate having a planar region substantially filled with reflection elements having a plurality of substantially spherical partial shapes arranged at random.