JPH11281967A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the reflection of incident light and to prevent contrast from decreasing by providing at least one side electrode substrate with a transparent electrode laminating a mixed oxide layer, a silver base alloy layer, an intermediate oxide layer, a silver base alloy layer, and a mixed oxide layer. SOLUTION: When an overcoat 15 (refractive index approximately 1.5) is in contact with a mixed oxide layer 25 (refractive index approximately 2.1), reflected light R1 is reduced on the surface of the mixed oxide layer 25, therefore, to supplement this reduction, an intermediate oxide layer 23 and a mixed oxide layer 21 are provided under the mixed oxide layer 25, and light R3 , R5 which are reflected from these surfaces and in-phase with the reflected light R1 from the mixed oxide 25 are added thereto. Moreover, each of the reflected light R2 , R4 on the surface of the silver base alloy layers 24, 22 is reduced by dividing the silver base alloy layer into two. And the reflection of external incident light occurring at the interface is brought close to 0 as a whole by setting it so that the sum of the reflected light R2 and R4 has almost the same reflection amount as the reflected light R1 , R3 , and R5 (R2 and R4 are different phases from each other).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type or reflection type liquid crystal display device, and particularly to a liquid crystal display device such as a PDA, a display for a portable information device, a palm PC and a notebook type. The present invention relates to a liquid crystal display device having improved display quality by reducing surface (interface) reflection caused by external light.

[0002]

2. Description of the Related Art In recent years, the development of a reflection type liquid crystal display device using external light has been active. As the reflection type liquid crystal display device, for example, as shown in the cross-sectional view of FIG. 4, a rear electrode substrate (40) having a reflection electrode (42) formed on a transparent substrate (41), and a transparent substrate (47). ) On which a color filter (46), a transparent electrode (44), etc. are formed, and an electrode substrate (49) on the observer side, and a structure in which a reflection type liquid crystal display device is configured via a liquid crystal (43). Many have been proposed.

In FIG. 4, a color filter (46)
Are formed as light transmissive pixels colored R (red), G (green), and B (blue), for example. Conventionally,
As the reflective electrode (42) formed on the back electrode substrate (40) shown in FIG. 4, an aluminum thin film is often used, and the aluminum thin film is a metal having a high light reflectance in the visible region. However, the reflectance of the aluminum thin film is not always satisfactory, and the reflectance is further reduced when the aluminum thin film is used in contact with liquid crystal or glass.

In the case of a reflection type liquid crystal display device having the structure shown in FIG. 4, a color filter (46), an overcoat (45), a transparent electrode (44) and the like are provided on a transparent substrate (47) on the viewer side. Are stacked, but when the display image is viewed from the observer side, the transparent electrode (44) and the overcoat (4)
At the interface with 5), external light is partially reflected. This reflected light increases as the refractive index ratio between the transparent electrode and the overcoat increases, and increases as the incident angle of external light on the display surface increases. Also, this reflected light
Regardless of whether the liquid crystal is on or off, the contrast of the display device is reduced like stray light. The same applies to the transmissive liquid crystal display device. In particular, the transmissive liquid crystal display device has a problem when the illuminance of external light is high (for example, outdoors when the weather is good).

As a related technique for reducing the reflection of the incident light from the outside at the interface, for example, Japanese Patent Application Laid-Open No.
7326 proposes that “a transparent electrode having a three-layer structure of an oxide layer / a silver layer / an oxide layer is a transparent electrode that is effective in reducing reflection and has high conductivity”. However, in the three-layer structure according to this technique, as shown in FIG. 3, the reflected light of the incident light (I) from the outside on the surface of the first oxide layer (33) is r ₁ , some of the transmitted light not reflected by the layer (33) surface is reflected by the silver layer (32) surface becomes reflected light r _2.

At this time, the overcoat (3) shown in FIG.
Since the ratio of the refractive index of 4) to the refractive index of the oxide layer (33) is small, the transmitted light increases, and the reflected light r ₁ is converted from the oxide layer (33) to air (refractive index: 1.0). in which becomes smaller than the reflected light r _'1 when in contact. The degree of the decrease is that the sum of the reflected light r ₁ and the reflected light r _{3 on} the surface of the second oxide layer (31) is the reflected light r ₂ (r ₁ and r ₁ ) on the surface of the silver layer (32). (The phase is different from ₃ ), the reflected light r ₁ and the reflected light r ₃ are smaller, so that the interference effect does not work sufficiently,
The reflection of the incident light at the interface is hardly reduced. That is, for example, as shown in FIG. 3, when the transparent electrode having the three-layer structure is used in a structure in which a resin or the like such as an overcoat (34) is in contact with the upper layer, the transparent electrode on the surface of the oxide layer (33) is formed. The reflected light is weakened, the reflected light on the surface of the silver layer (32) is increased, and the effect of reducing the reflection of the incident light at the interface as a whole is small.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to provide an interface between an overcoat on a viewer-side electrode substrate and a transparent electrode. An object of the present invention is to provide a liquid crystal display device having a high display quality by preventing a decrease in contrast of the liquid crystal display device by reducing reflection of incident light from the outside caused by the above. Another object of the present invention is to provide a reflective liquid crystal display device in which reflection of incident light from the outside is reduced. Another object of the present invention is to provide a liquid crystal display device having a reflective electrode having high light reflectivity. Another object of the present invention is to provide a liquid crystal display device having a light-reflective reflective electrode having excellent adhesion. Another object of the present invention is to provide a liquid crystal display device that does not reduce the reliability of the transparent electrode. Another object of the present invention is to provide a liquid crystal display device in which reflection of incident light from the outside is significantly reduced.

[0008]

According to a first aspect of the present invention, at least one of a pair of electrode substrates constituting a liquid crystal display device has a mixed oxide layer / silver alloy layer / intermediate oxide layer / A liquid crystal display device comprising a transparent electrode having a stacked silver alloy layer / mixed oxide layer. Further, the present invention is the liquid crystal display device according to the above invention, wherein the one-side electrode substrate is an observer-side electrode substrate. Further, according to the invention, in the liquid crystal display device of the invention, the electrode substrate on the other side of the electrode substrate on one side is an electrode substrate on the back side provided with a light-reflective reflective electrode. It is a liquid crystal display device. Further, according to the invention, in the liquid crystal display device according to the invention, the light-reflective reflective electrode is formed of a thin film of aluminum, silver, or an alloy of these metals and another metal. It is a liquid crystal display device. Further, according to the present invention, in the liquid crystal display device according to the invention, the light-reflective reflective electrode is a reflective electrode composed of a mixed oxide layer / a silver alloy layer / a mixed oxide layer. Device.

According to a second aspect of the present invention, there is provided the liquid crystal display device according to the above invention, wherein the mixed oxide layer and the intermediate oxide layer are amorphous or amorphous-like oxides. is there. According to a third aspect of the present invention, in the liquid crystal display device of the above aspect, the mixed oxide layer and the intermediate oxide layer are oxides having a refractive index of 1.9 or more. It is.
According to a fourth aspect of the present invention, in the liquid crystal display device according to the above aspect, the optical thickness of the intermediate oxide layer is approximately twice the optical thickness of the mixed oxide layer. It is a liquid crystal display device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device according to the present invention will be described in detail based on one embodiment. FIG. 1 is an explanatory diagram showing a cross section of one embodiment of the liquid crystal display device according to the present invention. In FIG. 1, a liquid crystal display device includes a polarizing plate (18), an electrode substrate (19) on the viewer side, and a liquid crystal (1).
3), the back side electrode substrate (10) and the like. The electrode substrate (19) on the observer side is provided with a color filter (1) on the liquid crystal (13) side of the transparent substrate (17).
6), an overcoat (15), a transparent electrode (14), and the like are laminated, and a polarizing plate (18) is disposed on the viewer side of the other surface of the electrode substrate (19). The back electrode substrate (10) is a liquid crystal (1) on a transparent substrate (11).
3) The reflective electrode (12) and the like are stacked on the side. And the transparent electrode (14) is a mixed oxide layer /
It is a transparent electrode in which a silver alloy layer / intermediate oxide layer / silver alloy layer / mixed oxide layer is laminated, and the electrode substrate (10) is a light-reflective reflective electrode, for example, mixed oxide layer / silver It is a reflective electrode in which an alloy layer / a mixed oxide layer is laminated.

FIG. 2 is an explanatory view showing the principle of reducing the reflection of incident light from the outside generated at the interface between the overcoat and the transparent electrode of the liquid crystal display device according to the present invention. FIG.
Wherein the transparent electrode (14) comprises a mixed oxide layer (25),
The transparent electrode (14) is composed of a silver alloy layer (24), an intermediate oxide layer (23), a silver alloy layer (22), and a mixed oxide layer (21). It is in contact with the overcoat (15). Also, I is incident light, R ₁
To R ₅ incident light indicates light reflected at the interface of each layer constituting the transparent electrode (14).

The liquid crystal display device according to the present invention has an
Of external incident light generated at the interface between the heat sink and the transparent electrode
The principle of reducing radiation is as follows. Sand
2, as shown in FIG.
Index of about 1.5) and the mixed oxide layer (25) (refractive index of about 2.
When 1) comes into contact, the reaction on the surface of the mixed oxide layer (25)
Glow R₁Mixed oxidation to compensate for this
Oxide layer (23) below the material layer (25), mixed oxidation
Layer (21), mixed oxides from these surfaces
Light R reflected on the surface of the layer (25)₁Reflected light with the same phase as
R_Three, R _FiveIs added. In addition, one layer
The thick silver alloy layer formed has large reflected light.
Then, this is divided into two, and the silver composite composed of two thin layers
The layers are gold layers (24) and (22). Thus, the silver alloy layer
Is divided into two to form silver alloy layers (24) and (22).
Light R on the surface of_Two, R_FourTo make each of the smaller
is there. Then, the surface of the silver alloy layers (24) and (22)
Reflected light R_TwoAnd R_FourAnd mixed oxide layer (25), intermediate
From the surface of the oxide layer (23) and the mixed oxide layer (21)
Reflected light R₁And R_ThreeAnd R_Five(R_Two, R_FourPhase is different)
Is set so that the sum of
The reflection of incident light from outside caused by
It is intended to be attached.

The silver alloy layers (24) and (2) used in the present invention
2) uses an alloy in which silver, gold, copper, platinum, palladium, nickel or the like is added in a small amount within a range that does not significantly affect the conductivity of silver. The addition amount is desirably 3 at% or less based on silver. The thickness of the silver alloy layer may be set in the range of 6 nm to 30 nm so that the transmittance of the five-layered transparent electrode is not significantly reduced.

The mixed oxide layer (25) used in the present invention,
The higher the refractive index of (21) is, the lower the reflectance can be and the higher the transmittance can be. Indium oxide and zinc oxide have a refractive index in the range of 1.8 to 2.0 and are suitable.
A mixed oxide having a higher refractive index can also be used by adding a high refractive index oxide to them. Representative examples include cerium oxide and titanium oxide, and their refractive indexes are about 2.4 to 2.5 at a wavelength of 550 nm. A mixed oxide of these and a conductive oxide is mixed oxide layer (25),
(21) and an intermediate oxide layer (23).

The thickness of the mixed oxide layer is preferably set in the range of 20 to 50 nm. When the refractive index of the mixed oxide is high, the film thickness is small, and when the refractive index is low, the film thickness is large. The intermediate oxide layer has a thickness of 2
It is preferable to set the thickness twice as large in the range of 40 to 100 nm. However, in the case of the intermediate oxide layer, it may be formed thinner than 40 nm in order to improve the electron transfer between the two silver alloy layers. The thickness of the mixed oxide layer is 20 nm.
If the layer is formed thinner, the reflection of the silver alloy layer cannot be sufficiently suppressed.

A five-layer transparent electrode (14) according to the present invention.
In a transmissive liquid crystal display device, can be used for both substrates that sandwich liquid crystal. However, in the reflection type liquid crystal display device, as shown in FIG. 1, the back side electrode substrate (1) facing the observer side electrode substrate (19).
For example, to form a light-reflective reflective electrode (12) on the transparent substrate (11) of (0), the five-layered transparent electrode comprises:
Only one of the electrode substrates on the observer side is required.

The five-layered transparent electrode according to the present invention can be used not only for a liquid crystal display device but also for a solar cell electrode, a heat ray reflection film, an electromagnetic wave shielding film, and by taking advantage of a low reflectance. It can also be formed on the display surface as an antireflection film for a liquid crystal display device or the like.

In the case of the reflection type liquid crystal display device, the back side electrode substrate (1) facing the observer side electrode substrate (19).
On the transparent substrate (11) of FIG.
2) needs to be formed. As the reflection electrode (12), a transparent electrode such as ITO may be laminated on an optical interference filter in which inorganic oxides are laminated in multiple layers. However, it is convenient to use a metal thin film of aluminum, silver, or an alloy thereof having both high reflectivity and high conductivity processed into a desired shape.

In the present invention, the light-reflective reflective electrode (1) is used.
2) is characterized by being formed of a thin film of aluminum, silver, or an alloy of these metals and other metals. The metal to be added to aluminum or silver may be a metal that improves adhesion, such as titanium, tantalum, or magnesium, if the main purpose is to impart adhesion to a substrate such as glass, for example, 0.5 to 3.0. % May be added. If the main purpose is to impart reflectance or conductivity, a small amount of aluminum, silver, or a metal having little effect on the free electrons of each atom may be added. In addition, when an oxide is laminated on these metal thin films for the purpose of imparting protection or enhanced reflection performance to aluminum or silver, a metal for adjusting a contact potential difference with the oxide or a work function is used. What is necessary is just to add a small amount.

The metal having the highest reflectance among the metals is silver. However, silver has poor adhesion to substrates such as glass and plastic films, and is not preferred as a single metal thin film. In the present invention, for the purpose of protection and adhesion, a three-layer structure of a mixed oxide layer / silver alloy layer / mixed oxide layer is provided in which a silver alloy layer is sandwiched between mixed oxide layers. The thickness of the silver alloy layer of this reflective electrode is
Unlike the case of a transparent electrode, a sufficient reflectance can be secured. 8
The thickness is preferably 0 nm or more, preferably 100 to 200 nm.

The mixed oxide layer (2) used for the transparent electrode (14) and the reflective electrode (12) of the liquid crystal display device according to the present invention.
5), (21), It is desirable that the material of the intermediate oxide layer (23) is indium oxide or zinc oxide which is a conductive oxide. However, silver easily moves along the crystal grain boundaries of the oxide layer sandwiching the silver, and the diffusion of the silver lowers the reliability as an electrode. In other words, in order to suppress the movement of silver at the grain boundary, it is preferable to employ an amorphous or amorphous-like oxide having substantially no grain boundary for the mixed oxide layer and the intermediate oxide layer.

As described above, the material of the mixed oxide layer and the intermediate oxide layer is preferably indium oxide or zinc oxide. However, in order to obtain an amorphous or amorphous-like oxide, a different oxide must be used. 15% or more, preferably about 20% may be added. In the case of oxides having poor compatibility, the content is preferably about 10%. If the amount of the oxide is too large, the conductivity required for the mixed oxide layer or the intermediate oxide layer is lost. In particular, since the conductivity of the intermediate oxide layer greatly affects the resistance value of the five-layered transparent electrode, it is desirable that there be electrical conduction between the two layers of the silver alloy.

As a mixed oxide, an appropriate amount of an oxide such as cerium oxide, titanium oxide, niobium oxide, tantalum oxide, calcium oxide, or magnesium oxide may be added to indium oxide, zinc oxide, tin oxide, or the like. It may be a mixed oxide of two or more types in which zinc oxide and tin oxide are added to indium oxide. When the material is indium oxide, the mixed oxide layer is preferable in terms of conductivity.

In the present invention, the large reflected light of the silver alloy layer on the transparent electrode having the structure in which the silver alloy layer is sandwiched between the mixed oxide layers is offset by the reflected light of the mixed oxide layers having different phases. It is important to increase the reflected light of the mixed oxide layer. In order to increase the reflected light of the mixed oxide layer, a mixed oxide layer to which an oxide having a high refractive index is added is used. Examples of the oxide having a high refractive index include titanium oxide, cerium oxide, tantalum oxide, zirconium oxide, and the like, and an oxide of a metal having a large atomic weight. For example, the refractive index of indium oxide is approximately 1.9, and a transparent electrode having a high transmittance can be obtained by adding indium oxide.

The mixed oxide layer has a refractive index of about 2 to 2.1,
When the thickness of the intermediate oxide layer is about 80 nm when the thickness is about 40 nm, visible light,
The reflectance around 50 nm is low. Although the optimum thickness slightly varies depending on the thickness of the silver alloy layer or the refractive index of the material in contact with the transparent electrode, the optical thickness of the intermediate oxide layer is substantially equal to the optical thickness of the mixed oxide layer. If it is about twice, the reflectance of the transparent electrode will be low.

The electrode substrate on the observer side of the liquid crystal display device of the present invention has, for example, three colors of red (R), green (G) and blue (B), or yellow (Y) and magenta (M). ) And three color filters of cyan (C) may be provided. The liquid crystal display of the present invention includes a polarizing plate, a retardation plate,
/ 4 wavelength plate, optical rotation compensation film, microlens, light scattering film, diffraction grating, antireflection film, antiglare film, optical element such as hologram, etc., or TFT, M
A liquid crystal driving element such as an IM may be provided according to the purpose. The type of liquid crystal used is TN, ST
There is no limitation on the type of liquid crystal, such as N, OCB (HAN), polymer dispersion, ferroelectricity, antiferroelectricity, and guest host. Further, the present invention is not limited by the orientation of liquid crystal such as horizontal orientation and vertical orientation.

Hereinafter, embodiments of the present invention will be described specifically.

<Embodiment 1> A liquid crystal display device according to Embodiment 1 has a color filter (16), an overcoat (15), and a transparent electrode (14) as shown in FIG. The liquid crystal (1) is formed by the electrode substrate (19) and the rear electrode substrate (10) on which the reflective electrode (12) and the like are stacked.
In the configuration sandwiching 3), a polarizing plate (18) including a retardation film is disposed on the observer side of the electrode substrate (19) on the observer side.

The transparent electrode (14) has a width of about 90 μm.
m, a stripe shape having a pitch of about 100 μm, and the reflective electrode (12) having a width of about 290 μm and a pitch of about 300 μm.
m is formed in a stripe pattern, and the transparent electrode (1
It is orthogonal to 4). The transparent electrode, as shown in FIG.
A mixed oxide layer (25) with a layer thickness of about 40 nm, a silver alloy layer (24) of about 9 nm, an intermediate oxide layer (23) of about 82 nm,
The silver alloy layer (22) having a thickness of about 9 nm and the mixed oxide layer (21) having a thickness of about 40 nm had a five-layer structure.

The reflective electrode (12) was composed of three layers of a mixed oxide layer of about 20 nm, a silver alloy layer of about 150 nm, and a mixed oxide layer of about 4 nm from the transparent substrate (11) side. The reflective electrode was made of a thin mixed oxide on the side in contact with the liquid crystal in order to increase the reflectance on the short wavelength side. The sheet resistance of this transparent electrode is about 4Ω / □, and the sheet resistance of the reflection electrode is about 0.3Ω.
/ □. The composition of the mixed oxide layer and the intermediate oxide layer was 83 atomic% of indium, 8.5 atomic% of cerium, and 8.5 atomic% of zinc in atomic percentage of only metal elements excluding oxygen. The composition of the silver alloy layer was 98.5 silver.
at%, gold 1 at%, and copper 0.5 at%.

A comparison will be made between a liquid crystal display device using the transparent electrode thus obtained and a liquid crystal display device using a single layer of ITO (a mixed oxide of indium oxide and tin oxide) as the transparent electrode. In addition, the liquid crystal display device using the transparent electrode according to the present invention did not have white to greenish reflected light at the interface between the overcoat and the transparent electrode, and had high contrast display quality.

In the present invention, the effect of reducing the reflection of the liquid crystal display device was verified by simulation. A: Laminated structure of transparent electrode 1 Mixed oxide layer ‥‥ Refractive index 2.1, thickness 40 nm 2 Silver alloy layer 屈折 Refractive index 0.12, film thickness 10 nm 3 Intermediate oxide layer 屈折 Refractive index 2.1, 82 nm thickness 4 silver alloy layer 屈折 refractive index 0.12, thickness 10 nm 5 mixed oxide layer ‥‥ refractive index 2.1, thickness 40 nm The refractive index of the overcoat in contact with the transparent electrode is 1.5. And B Laminated structure of conventional transparent electrode 1 Mixed oxide layer 屈折 Refractive index 2.1, film thickness 40 nm 2 Silver alloy layer 屈折 Refractive index 0.12, film thickness 20 nm 3 Mixed oxide layer ‥‥ Refractive index 2 The thickness of the overcoat in contact with the transparent electrode was 1.5.

FIG. 5 shows the results of the simulation with the above configuration as the spectral reflectance A and the spectral reflectance B.
As shown in FIG. 5, the transparent electrode having the five-layer structure according to the present invention had lower reflection than the conventional three-layer transparent electrode when in contact with the overcoat having a refractive index of 1.5.

[0033]

According to the present invention, at least one of the pair of electrode substrates constituting the liquid crystal display device has a mixed oxide layer / silver alloy layer / intermediate oxide layer / silver alloy layer / mixed oxide layer. Is provided, the reflection of incident light from the outside is reduced, the contrast of the liquid crystal display device is prevented from lowering, and a liquid crystal display device with high display quality can be obtained. In addition, since the light-reflective reflective electrode is formed on the transparent substrate of the electrode substrate on the back side, a reflective liquid crystal display device in which the reflection of incident light from the outside is reduced can be obtained. In addition, since the light-reflective reflective electrode is formed of a thin film of aluminum, silver, or an alloy of these metals and another metal, a liquid crystal display device having a highly light-reflective reflective electrode can be obtained. Further, a light-reflective reflective electrode is formed by sandwiching a silver alloy layer with a mixed oxide layer.
Since the mixed oxide layer has a three-layer structure, a liquid crystal display device having a light-reflective reflective electrode having excellent adhesion can be obtained.

Further, according to the present invention, an amorphous or amorphous-like oxide having substantially no grain boundaries is used for the mixed oxide layer and the intermediate oxide layer, so that the reliability of the transparent electrode is not reduced. A device is obtained. Also,
In the present invention, in order to increase the reflected light of the mixed oxide layer, an oxide having a high refractive index is added to form a mixed oxide layer having a refractive index of about 1.9 or more. , A liquid crystal display device in which is greatly reduced. Further, the present invention provides that the optical thickness of the intermediate oxide layer is about 2 times the optical thickness of the mixed oxide layer.
Since it is about twice, a liquid crystal display device in which reflection of incident light from the outside is significantly reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a cross section of one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is an explanatory diagram showing the principle of reducing the reflection of incident light of the liquid crystal display device according to the present invention.

FIG. 3 is an explanatory diagram showing a principle of reducing reflection of incident light of a liquid crystal display device according to a conventional method.

FIG. 4 is an explanatory view showing an example of a conventional liquid crystal display device in a cross section thereof.

FIG. 5 is a simulation result of spectral reflectance.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Back electrode substrate 11, 17, 41, 47 ... Transparent substrate 12, 42 ... Reflection electrode 13 ... Liquid crystal 14, 44 ... Transparent electrode 15, 34 ... Overcoat 16 ... Color filter 18 ... Polarizing plate 19 ... Observer side of the electrode substrate 21,25,31,33 ... mixed oxide layer 23 ... intermediate oxide layer 22, 24 ... silver alloy layer 32 ... silver layer I ... incident light _{r 1 ~r 3, R 1 ~R} 5 ... reflector light

Claims (8)

[Claims] At least one of a pair of electrode substrates constituting a liquid crystal display device has a transparent structure in which a mixed oxide layer / silver alloy layer / intermediate oxide layer / silver alloy layer / mixed oxide layer is laminated. A liquid crystal display device comprising an electrode. 2. The liquid crystal display device according to claim 1, wherein said one electrode substrate is an observer-side electrode substrate. 3. The liquid crystal display device according to claim 2, wherein the electrode substrate on the other side of the electrode substrate on one side is an electrode substrate on the rear side provided with a light-reflective reflective electrode. 4. The liquid crystal display device according to claim 3, wherein said light-reflective reflective electrode is formed of a thin film of aluminum, silver, or an alloy of these metals and another metal. 5. The liquid crystal display device according to claim 3, wherein the light-reflective reflective electrode is a reflective electrode composed of a mixed oxide layer / silver alloy layer / mixed oxide layer. 6. A liquid crystal display device according to claim 1, wherein said mixed oxide layer and said intermediate oxide layer are amorphous or amorphous-like oxides. 7. The liquid crystal display device according to claim 1, wherein the mixed oxide layer and the intermediate oxide layer are oxides having a refractive index of 1.9 or more. 8. The liquid crystal display device according to claim 1, wherein the optical thickness of the intermediate oxide layer is approximately twice the optical thickness of the mixed oxide layer.