JPH075454A - Display panel and projection type display device using the same - Google Patents

Abstract

PURPOSE:To provide the display panel capable of making display with a high contrast and high fineness without light leakage between adjacent pixels. CONSTITUTION:A high-polymer dispersed liquid crystal 15 is clamped between an array substrate 13 and a counter substrate 14. Light absorptive thin films are formed on a black matrix and between pixel electrodes when the display panel is a transmission type display panel. The light absorptive thin films 20 are formed between reflection electrodes 18 when the display panel is of a reflection type. The counter electrode 12 is constituted of multilayered films successively laminated with dielectric thin films 12a, 12c and ITO thin films 12b. The optical film thickness of the ITO thin films is set at lambda/2 (where lambdais a design main wavelength) and the optical film thickness of the dielectric thin films at lambda/4. The multilayered films function as antireflection films. Dyestuff having a relation of a complementary color with the color of the incident light on a liquid crystal layer is incorporated into the light absorptive thin films 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a display panel which modulates incident light to form an optical image, and a projection type display which uses the display panel as a light valve and projects a display image of the display panel on a screen in an enlarged manner. It relates to the device.

[0002]

2. Description of the Related Art A display device using a liquid crystal panel has been actively researched and developed because it can be made light and thin. In recent years, a pocket television using a twisted nematic (TN) mode liquid crystal panel in which the optical activity of liquid crystal is applied to image display has been put into practical use. Further, a liquid crystal projection television and a viewfinder using the liquid crystal panel as a light valve have been put into practical use.

However, the liquid crystal panel using the TN liquid crystal has a problem that the display brightness is low because a polarizing plate is required to perform light modulation, and a rubbing process is required to align the liquid crystal molecules. The manufacturing process is also complicated. Therefore, in recent years, a liquid crystal panel using a polymer dispersed liquid crystal that does not require rubbing and does not use a polarizing plate for light modulation has been attracting attention. U.S. Pat. No. 4,435,047 is an example of a polymer dispersed liquid crystal panel, and U.S. Pat. No. 4,613,207 is an example of a projection type display device using a polymer dispersed liquid crystal panel as a light valve.

Hereinafter, the polymer dispersed liquid crystal will be briefly described with reference to FIG. Polymer dispersed liquid crystals are roughly classified into two types depending on the dispersion state of the liquid crystals and the polymers. One is a type in which liquid crystals in the form of water droplets are dispersed in a polymer. The liquid crystal exists in the polymer in a discontinuous state. Hereinafter, such a liquid crystal will be referred to as a PDLC, and a liquid crystal panel using the liquid crystal will be referred to as a PD liquid crystal panel. The other is a type having a structure in which a polymer network is stretched around the liquid crystal layer. It looks like a sponge containing liquid crystal. The liquid crystal does not form a water drop but continuously exists. After that, such liquid crystal is
Call it NLC. In order to display an image with the above-mentioned two kinds of liquid crystal panels, light scattering and transmission are controlled.

PDLC utilizes the property that the refractive index differs in the direction in which the liquid crystal is aligned. When no voltage is applied, each water droplet liquid crystal is oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer and the liquid crystal, and incident light is scattered. When a voltage is applied, the alignment direction of the liquid crystal is aligned. If the refractive index when the liquid crystal is oriented in a certain direction is matched with the refractive index of the polymer in advance, incident light is transmitted without being scattered.

On the other hand, PNLC uses the irregularity itself of the alignment of liquid crystal molecules. The incident light is scattered in the irregular alignment state, that is, in the state where no voltage is applied.
On the other hand, when a voltage is applied and the arrangement state is made regular, light is transmitted.

In FIG. 17A and 17B, 173
Is a water-drop liquid crystal and 174 is a polymer. Pixel electrode 17
A thin film transistor (hereinafter referred to as a TFT, not shown) or the like is connected to 2 and a voltage is applied to the pixel electrode 172 by turning the TFT on and off. Pixel electrode 172 depending on voltage
Light is modulated by changing the liquid crystal orientation direction of the upper liquid crystal 173 on the water droplet. As shown in (FIG. 17A), when no voltage is applied (OFF), each liquid crystal 1
Liquid crystal molecules in 73 are oriented in irregular directions. In this state, a difference in refractive index occurs between the polymer 174 and the liquid crystal, and incident light is scattered. As shown in FIG. 17B, when a voltage is applied to the pixel electrode 172, the directions of liquid crystal molecules are aligned. When the refractive index when the liquid crystal molecules are aligned in a certain direction is matched with the refractive index of the polymer 174 in advance, incident light is emitted from the pixel electrode 172 side of the array substrate 12 without being scattered.

[0008]

Since the polymer-dispersed liquid crystal panel does not require a polarizing plate for light modulation, it is possible to display a high-intensity display which is more than twice as bright as a TN liquid crystal panel. But,
There are many issues. One of the problems is a phenomenon in which light scattered by a pixel propagates to a pixel adjacent to the pixel (light leakage) and the contour of the pixel is blurred. The degree of influence is particularly high in an image displayed in black and white with a minute interval. That is, scattered light from an adjacent pixel wraps around a pixel that is originally black display or white display, and black display or white display becomes gray display.

An example of a method for solving such a problem is
It is disclosed in Japanese Patent Application Laid-Open No. 4-84121. In the liquid crystal display panel disclosed in this publication, polymer dispersed liquid crystal is used as liquid crystal, and a wall made of saturated hydrocarbons colored in black is formed between pixel electrodes. This wall absorbs the light scattered by a certain pixel and prevents the light leakage from occurring in the adjacent pixel.

The film thickness of the polymer-dispersed liquid crystal needs to be formed to 10 μm or more. Therefore, the wall needs to be 10 μm or more. The height of 10 μm or more may be realized when the polymer dispersed liquid crystal is formed by a printing method as disclosed in the publication. However, the effective display area is 3-4
It is impossible to realize with a high-definition liquid crystal panel that has more than 1 million pixels on an inch liquid crystal panel. This is because the pixel size of the liquid crystal panel is about 50 μm square and the distance between the pixel electrodes is about 5 μm. Therefore, the wall must be 5 μm wide and 10 μm or more.
The width of 5 μm is too small to be realized by the pattern printing method. A pattern having a width of 5 μm can be realized by using a vapor deposition technique such as sputtering, but a height of 10 μm or more cannot be realized.

Another problem is that the walls are made of a carbide material. Many carbides have poor insulating properties. Since the wall is formed between the pixel electrode and the counter electrode, there is a high possibility that the insulation resistance in the pixel electrode and the counter electrode will be reduced. In addition, carbides often react with components of the liquid crystal material to deteriorate the liquid crystal.

[0012]

The display panel of the present invention comprises:
Polymer dispersed liquid crystal is sandwiched between the first electrode substrate and the second electrode substrate. When the display panel is a transmissive display panel, a light absorbing thin film is formed on the black matrix and / or between the pixel electrodes. In the case of a reflective display panel,
A light absorbing thin film is formed between the reflective electrodes. In the case of a photo-writing type display panel, a light absorbing thin film is formed on the dielectric mirror. The light-absorbing thin film contains a dye having a complementary color relationship with the color of light incident on the liquid crystal layer.

When the display panel is an optical writing type or a reflection type, the counter electrode has a multilayer film structure of a dielectric thin film and an ITO thin film. The ITO thin film is λ / 2 (where λ is the designed main wavelength), and the optical thickness of the dielectric thin film is λ / 4. The multilayer film functions as an antireflection film.

The transparent substrate is adhered to the electrode substrate, the distance t from the position where the transparent substrate comes into contact with air to the polymer dispersed liquid crystal layer, the refractive index of the transparent substrate, and the maximum diameter of the effective display area of the display panel. When d, it is preferable to satisfy the relationship of (Equation 1).

[0015]

[Equation 1]

The projection display device of the present invention uses the display panel of the present invention as a light valve. White light emitted from the metal halide lamp is separated into three light paths of blue light, green light and red light, and the display panel of the present invention is arranged in each of the light paths. The display panel modulates the incident light by switching between the transmission state and the scattering state through the liquid crystal layer according to the applied video signal. The modulated light is enlarged and projected on the screen by the projection lens.

[0017]

In the display panel of the present invention, the polymer dispersed liquid crystal layer is sandwiched between the first and second electrode substrates, at least one of which is light transmissive, and at least one of the first and second electrode substrates is provided. A light absorption thin film is formed on the surface above and in contact with the polymer dispersed liquid crystal. The light absorbing thin film contains a dye that absorbs the light modulated by the polymer dispersed liquid crystal layer, and preferably contains a dye having a complementary color relationship with the color of the light. The light absorbing thin film can absorb the light scattered in the liquid crystal layer and prevent light leakage between pixels.

When the display panel is a transmissive display panel,
At least one of the light shielding pattern (hereinafter, referred to as a black matrix) formed between the pixel electrodes and the substrate (hereinafter, referred to as a counter electrode substrate) that faces the pixel electrode and the polymer-dispersed liquid crystal layer is provided. Form a light absorbing thin film.

When the display panel is a reflection type display panel, the light absorbing thin film is formed between the reflection electrodes formed in a matrix or on the reflection means such as a dielectric mirror. In addition, a multilayer film composed of a dielectric thin film and an ITO thin film used for applying an electric field to the polymer dispersed liquid crystal layer is formed on the counter electrode substrate which faces the reflection means and the polymer dispersed liquid crystal layer. . The multilayer film is composed of two layers, a dielectric thin film having an optical film thickness of λ / 4 (λ is a designed main wavelength of light) and an ITO thin film having an optical film thickness of λ / 2. At that time, a material having a light transmittance of a dielectric thin film having a refractive index of 1.5 or more and 1.7 or less is selected. More preferably, the multilayer film is composed of three layers of a first dielectric thin film, an ITO thin film, and a second dielectric thin film. The optical thickness of the first and second dielectric thin films is λ / 4, and the optical thickness of the ITO thin film is λ / 4.
To Further, the first and second dielectric thin films have a refractive index of 1.6 or more and 1.8 or less and a light-transmissive material is selected. The above-mentioned multi-layer film is an
It has both the function of preventing light reflected at the interface of the O thin film and the function of applying an electric field to the liquid crystal.

At least one of the first electrode substrate and the second electrode substrate preferably satisfies the following condition or shape. When both surfaces of the electrode substrate are flat, the distance from the surface of the electrode substrate in contact with air to the polymer dispersed liquid crystal layer is t, the effective display area of the polymer dispersed liquid crystal layer is d, and the refractive index of the substrate is n. Then, the relation of (Equation 2) is satisfied.

[0021]

[Equation 2]

Further, a light absorbing film is formed on the ineffective surface of the electrode substrate (portion other than the effective display area) by using black paint or the like.
If the above relationship is satisfied, light that is scattered by the liquid crystal layer and reflected at the interface between the substrate and air can be absorbed by the light absorbing film, and the display contrast can be improved. As the substrate, a laminated structure of a counter electrode substrate and a transparent substrate may be used to satisfy the relational expression. Further, when the surface of the substrate that contacts air is a curved surface, the value of t in the above relational expression may not be satisfied. However, it is preferable that the curved surface has a concave lens shape.

The projection display device of the present invention uses the display device of the present invention as a light valve. Using a dichroic mirror or dichroic prism, separate the light from lamps such as metal halide lamps and xenon lamps into the optical paths of the three primary colors of red light (R light), blue light (B light) and green light (G light). . The display panel of the present invention is arranged in each optical path. The display panel may be either a reflective or transmissive display panel. The display panel modulates incident light. The modulated light is enlarged and projected on the screen by the projection optical system.

[0024]

1 is a sectional view of an embodiment of the display panel of the present invention. Note that the following drawings are drawn as models and do not match the physical film thickness or shape. In addition, parts unnecessary for explanation are omitted.

On the array substrate 13, a reflective electrode 18 made of Al, a thin film transistor (TFT) 16 for applying a signal to the reflective electrode 18, a source signal line 23 for transmitting a signal to the TFT 16 and the like are formed. , TF
One terminal of T16 and the reflective electrode 18 are connected by a contact portion 19. The portion other than the contact portion 19 is separated by the insulating film 17. The material of the insulating film 17 is an organic material such as polyimide, SiO ₂ , SiN _x.
Inorganic materials such as In order to improve the specularity of the reflective electrode 18, after patterning the reflective electrode 18, the surface of the reflective electrode is polished in a polishing process to be a mirror surface.

The counter electrode substrate 14 is a glass substrate, and the counter electrode 12 or 25 also serving as an antireflection structure is formed on the surface in contact with the polymer dispersed liquid crystal layer 15 which is a light modulation layer. A bead (not shown) or the like holds a space between the counter electrode and the reflection electrode 18 at a predetermined interval, and a polymer dispersed liquid crystal 15 for performing light modulation is sandwiched between the spaces. The counter electrode substrate 14 is a glass substrate having a thickness of 1 mm and has a refractive index of 1.52.

Polymer dispersed liquid crystal layer 15 constituting the light modulation layer
The nematic liquid crystal, the smectic liquid crystal and the cholesteric liquid crystal are preferable as the liquid crystal material of the single or 2
It may be a mixture containing more than one kind of liquid crystal compound or a substance other than the liquid crystal compound. Among the above-mentioned liquid crystal materials, a cyanobiphenyl nematic liquid crystal having a relatively large difference between the extraordinary light refractive index n _e and the ordinary light refractive index n _o is preferable. Alternatively, a fluorine-based nematic liquid crystal having good light resistance and heat resistance is preferable.

As the polymer matrix material, a transparent polymer is preferable, and as the polymer, a thermoplastic resin,
Either a thermosetting resin or a photocurable resin may be used, but it is preferable to use an ultraviolet curable resin from the viewpoint of ease of manufacturing process, separation from the liquid crystal phase and the like. As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or an acrylic oligomer which is polymerized and cured by ultraviolet irradiation is particularly preferable.

As such a polymer-forming monomer,
2-Ethylhexyl acrylate, 2-hydroxyethyl acrylate, neopentyl glycol acrylate, hexanediol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol acrylate and the like.

Examples of the oligomer or prepolymer include polyester acrylate, epoxy acrylate and polyurethane acrylate.

A polymerization initiator may be used to accelerate the polymerization, and as an example thereof, 2-hydroxy-2-
Methyl-1-phenylpropan-1-one (“Darocur 1173” manufactured by Merck), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-
On (Merck "Darocur 1116"), 1-vidroxycyclohexyl phenyl ketone (Ciba-Gaiki "Irgacure 184"), benzyl methyl ketal (Ciba-Geigy "Irgacure 651") and the like. In addition, a chain transfer agent, a photosensitizer, a dye, a cross-linking agent and the like can be appropriately used in combination as optional components.

The refractive index n _p when the resin material is cured
And the ordinary refractive index n _o of the liquid crystal are made to substantially match.
When an electric field is applied to the liquid crystal layer, the liquid crystal molecules are oriented in one direction, and the refractive index of the liquid crystal layer becomes n _o . Therefore, the refractive index n _{p of the} resin matches, and the liquid crystal layer is in a light transmitting state. If the difference between the refractive indices n _p and n _o is large, the liquid crystal layer will not be completely transparent even when a voltage is applied to the liquid crystal layer, and the display brightness will decrease.

Although the proportion of the liquid crystal material in the polymer dispersed liquid crystal layer is not specified here, it is generally about 20% to 90% by weight, preferably about 50% to 85% by weight. When it is 20% by weight or less, the amount of liquid crystal drops is small,
The scattering effect is poor. On the other hand, when it is 90% by weight or more, the polymer and the liquid crystal tend to be phase-separated into upper and lower two layers, the ratio of the interface becomes small, and the scattering property is deteriorated. The structure of the polymer-dispersed liquid crystal layer changes depending on the liquid crystal ratio, and is approximately 50
When the amount is less than 50% by weight, the liquid crystal droplets exist as independent droplets, and when the amount is more than 50% by weight, the polymer and the liquid crystal form a continuous layer intricately intermingled with each other.

The thickness of the liquid crystal layer 15 is preferably in the range of 5 to 25 μm, more preferably 8 to 15 μm. If the film thickness is thin, the scattering characteristics are poor and the contrast cannot be obtained. On the contrary, if the film thickness is large, high voltage driving must be performed.
It becomes difficult to design a drive IC for driving the IC.

11 and 24 are air and the counter electrode substrate 1.
4 is an antireflection film that prevents interface reflection with 4. As the antireflection film, there are a multi-coat method for reducing the reflectance in a relatively wide wavelength band of visible light and a V-coat method for reducing the reflectance in a specific wavelength band. The V coat is suitable for preventing reflected light as much as possible in a narrow light wavelength band. When modulating white light, that is, a wide wavelength band, the multi-coat method is used. (FIG. 1A) shows a V-coat method (antireflection film 1).
1) and (FIG. 1B) show a structure in which a multi-coat method (antireflection film 24) is applied.

In the multi-coat method (shown in FIG. 1 (b)), Al ₂ O ₃ 24a has an optical film thickness of λ / 4 and ZrO ₂ 24 is formed.
b is formed by vapor-depositing a three-layer thin film having an optical film thickness of λ / 2 and MgF ₂ 24c having an optical film thickness of λ / 4. In the case of the V coat method, as shown in (FIG. 1A), Y ₂ O ₃ 11a
Is formed by vapor-depositing a two-layer thin film having an optical film thickness of λ / 4 and MgF ₂ 11b having an optical film thickness of λ / 4. In addition, Y ₂ O ₂
Alternatively, S _i O may be used, but since SiO has an absorption band for blue light, it is preferable to use Y ₂ O ₃ . (Fig. 1
The solid line in 8) indicates the spectral reflectance of the V coat, and the dotted line indicates the spectral reflectance of the multi coat.

A counter electrode and an antireflection film are formed on one surface of the counter electrode substrate 14. To be exact, I as the counter electrode
A dielectric thin film is formed before and after or on one side of the TO film to form an antireflection film. Hereinafter, a structure in which the counter electrode and the antireflection film are integrated is referred to as an antireflection electrode.

In the display panel of the embodiment shown in FIG. 1, the black matrix is not formed on the antireflection electrode 12 or 25. When the black matrix is formed, a solution in which liquid crystal and resin are mixed is injected between the array substrate 13 and the counter electrode substrate 14 at the time of manufacturing the liquid crystal panel,
This is because the solution in the lower layer of the black matrix becomes unpolymerized when the liquid crystal and the resin are phase-separated by irradiation with ultraviolet rays. The unpolymerized state results in lack of material stability of the light modulation layer 15, which causes performance deterioration. Moreover, the black matrix lowers the pixel aperture ratio. In addition, (Fig. 1
In a reflection type display panel (as shown in Fig. 3), incident light is reflected by the black matrix, and a white black matrix pattern is displayed on the screen. This also applies to the display panel of the embodiment shown later (FIG. 10).

In the conventional reflection type light valve configuration,
The contrast is reduced by the reflected light generated at the interface between the air and the counter electrode substrate, at the interface between the ITO thin film serving as the counter electrode and the substrate, and at the interface between the ITO thin film and the liquid crystal layer.

The reflectance R (%) generated at the boundary surface between two different refractive indexes n _A and n _B can be obtained by (Equation 3).

[0041]

[Equation 3]

When the counter electrode substrate is made of glass, usually, assuming that the refractive index of the glass substrate is 1.52 and the refractive index of air is 1.0, the reflectance generated at the interface between the glass substrate and air is about. It becomes 4%.

When a thin film having a refractive index n _C and a film thickness d is formed between two refractive indices n _A and n _B , the reflectance R (%) at the wavelength λ is (Equation 4). Desired.

[0044]

[Equation 4]

When an ITO thin film is used as the counter electrode,
Assuming that the refractive index of the ITO thin film is 2.0, the refractive index of the glass substrate is 1.52, and the refractive index of the liquid crystal layer is 1.6, the reflectance depends on the thickness of the thin film, and the maximum reflectance is about 6 at a certain wavelength. %
It also becomes.

Therefore, when the display panel as described above is used to form a reflection type structure, a maximum of about 10% of light does not enter the liquid crystal layer and is reflected. Reflected light causes a decrease in contrast.

In order to provide the counter electrode with an excellent antireflection function, the optical film thickness of the dielectric thin film formed on one surface or both surfaces of the ITO thin film to be the counter electrode is important.

In the conventional TN liquid crystal, it is necessary to form an alignment film. The thickness of the alignment film cannot be formed while controlling the film thickness with an accuracy of about 10Å. Therefore, IT
It is not possible to form an alignment film on one surface of the O thin film and cause the alignment film and the ITO thin film to interfere with each other so as to have an antireflection function. Conversely, even if a dielectric thin film such as Al ₂ O ₃ is formed on ITO and has an antireflection function, the antireflection function is lowered or the antireflection function disappears due to the formation of the alignment film.

The polymer-dispersed liquid crystal does not require the formation of an alignment film. Therefore, a good antireflection film can be formed by forming a dielectric thin film made of an inorganic material before and after using an ITO thin film as a counter electrode.

In order to reduce the reflection that occurs at the front and back boundary surfaces of the ITO thin film serving as the counter electrode, at least a transparent dielectric thin film and an ITO thin film having a refractive index and a film thickness satisfying a specific condition are used. It is sufficient to form a two-layered multilayer film. In the case of the two-layered antireflection film 25 as shown in FIG. 1B, the conditions for minimizing the reflectance are as follows.

[0051]

[Equation 5]

[0052]

[Equation 6]

[0053]

[Equation 7]

[0054]

[Equation 8]

N _G is the refractive index of the glass substrate 14, n _LC is the refractive index of the liquid crystal layer 15, n ₁ is the refractive index of the thin film formed between the glass substrate 14 and the ITO thin film 25, and n ₂ is the ITO thin film 25. D ₁ is the refractive index of the glass substrate 14 and the ITO thin film 25.
thin film having a film thickness to be formed between the b, d ₂ is the ITO thin film 25
The film thickness of b, λ, is the designed dominant wavelength. The glass substrate 1
The thin film formed between 4 and the ITO thin film 25b may be formed between the liquid crystal layer 15 and the ITO thin film 25b. Here, the film thickness d _i ( _i = 1, 2) means the physical film thickness, and n _i d _i means the optical film thickness.

All of the above conditional expressions are non-reflective conditions at the wavelength λ, but in the case of reducing reflection in a wide wavelength band, (Equation 5), (Equation 5), (Equation 5), (Equation 5), (Equation 8) It is preferable to satisfy the condition of Expression 6). Furthermore, IT
In order to obtain a sufficiently low resistance value, the O thin film 15b preferably has a physical film thickness of at least 100 nm or more. From this point as well, the condition of the optical film thickness n ₂ d ₂ of the ITO thin film is λ / 2.
The conditions of (Equation 5) and (Equation 6) are preferable.

The antireflection electrode 25 shown in FIG. 1 (b).
Is constructed based on the above conditional expression. A dielectric thin film 2 having a refractive index higher than that of the counter electrode substrate 14 and lower than that of the ITO thin film 25b serving as a counter electrode.
5a and an ITO thin film 25b serving as a counter electrode, which has a two-layer structure. The ITO thin film 25b has an optical film thickness of λ / 2, and the dielectric thin film 25a has an optical film thickness of λ / 4. Further, the refractive index of the dielectric thin film 25a is set higher than that of the liquid crystal layer 15 in which no electric field is applied. That is, if the refractive index n ₁ of the dielectric thin film, the refractive index n ₂ of the ITO thin film, and the refractive index n ₃ of the liquid crystal layer in the absence of applied electric field, then n ₂ > n ₁ > n ₃ . This also applies to the antireflection electrode (FIG. 1A).

An example of a concrete structure is shown in (Table 1), and its spectral reflectance is shown by a solid line in FIG. (Fig. 2
As can be seen from (0), according to the configuration of (Table 1), the characteristic of the reflectance of 0.3% or less can be realized over the wavelength bandwidth of 100 nm or more, and the reflected light can be significantly reduced.

[0059]

[Table 1]

The refractive index n _x of the polymer dispersed liquid crystal 15 when no voltage is applied is theoretically expressed by the following equation.

[0061]

[Equation 9]

N _o is the ordinary refractive index of the liquid crystal, and n _e is the extraordinary refractive index. In the case of a cyanobiphenyl type liquid crystal, n _o is about 1.50 and n _e is about 1.75. n _e and n _o
The larger the refractive index difference Δn, the better the scattering characteristics. Fluorine-based liquid crystals are relatively small in both _ne and Δn, and cannot obtain very high scattering characteristics. However, the heat resistance and the light resistance are good, and the relative permittivity of the liquid crystal is relatively low. Therefore, the voltage is more easily applied to the fluorine-based liquid crystal than to the cyanobiphenyl-based liquid crystal. Therefore, although the scattering property per film thickness is low, a good scattering property can be obtained by increasing the film thickness of the liquid crystal.

Substituting n _o and n _e of the above cyanobiphenyl system into (Equation 9) results in n _x ≈1.6. The actual light modulation layer 15 is a mixed layer of polymer and liquid crystal. In many cases, the refractive index n _{p of the} polymer is made to substantially coincide with n _o , so that the refractive index n _x of the polymer-dispersed liquid crystal in the no electric field is 1.6.
Even smaller than.

The refractive index of the liquid crystal shown in the tables and texts in this specification is 1.6. As is clear from the above description, this is the highest refractive index for practical use, and is actually smaller than that. The spectral reflectance has the smallest value when the refractive index of the glass substrate and the refractive index of the liquid crystal layer match. The refractive index of the liquid crystal layer does not significantly exceed 1.6, is actually smaller than 1.6, and is close to the refractive index of the glass substrate.

The refractive index of the thin film 25a is 1.50 or more and 1.7.
It is preferably 0 or less, more preferably 1.6 or more and 1.7.
The following is desirable. Although Al ₂ O ₃ was used in the examples of (Table 1), CeF ₃ , SiO, WO ₃ , LaF ₃ , and NdF _{3 are also used.}
Either of these may be used.

Table 2 shows an example in which Al ₂ O ₃ is changed to SiO. The dotted line in FIG. 20 shows the spectral reflectance when SiO is used.

[0067]

[Table 2]

If SiO is used, 400 nm to 700
A spectral reflectance of 1% or less can be realized over the wavelength band of nm. In the projection display device of the present invention, R light, G light and B light are used.
Three display panels that modulate light are used as light valves. Spectral reflectance characteristics (Al ₂
The reflectance in the vicinity of G light is extremely small for O ₃ ), but the reflectance is high for B light and R light. Therefore, it is necessary to form the antireflection electrode 25 corresponding to the R, G, and B lights, and three types of display panels must be used for one projection display. In the spectral reflectance characteristic (SiO) shown by the dotted line in (FIG. 20), since the reflectance is 1% or less over the entire R light, G light, and B light, there is a high possibility that it can be shared by one type of panel.

What is important in the display panel of the present invention is that the antireflection film is formed using the ITO thin film as the counter electrode. As a matter of course, the ITO thin film is constructed or formed so that a voltage can be applied. The ITO thin film may be a film of indium oxide, tin oxide or the like. Also in that case, the dielectric thin film may be laminated with an optical thin film that reduces the reflectance due to the optical interference effect.

A reflective electrode 18 is formed on the TFT 16 via an insulating film 17. Reflective electrode 18 and TFT1
6 is electrically connected by a connection terminal 19. As a material for the insulating film 17, an organic material typified by polyimide or the like or an inorganic material such as SiO ₂ or SiNx is used. The surface of the reflective electrode 18 is formed of a thin film of aluminum (Al). Although it may be formed by using Cr or the like, the reflectance is lower than that of Al, and since it is hard, a problem easily occurs such that the peripheral portion of the reflective electrode 18 is covered.

The connection terminal 19 portion of the reflective electrode 18 is 0.5 to
Although a depression of 1 μm can be formed, the polymer-dispersed liquid crystal 15 does not require a treatment such as alignment, and therefore alignment failure due to unevenness does not occur unlike the TN liquid crystal. The aperture ratio is 100 pixels
80% or more for μm square, 70% for 50 μm square
The above aperture ratio is obtained. However, the reflection electrode 18 on the TFT 16 is transferred with the pattern of the TFT to form irregularities, and the reflection efficiency is somewhat lowered. In order to eliminate the unevenness, the surface of the reflective electrode 18 may be polished. The reflection electrode 18 is smoothed by polishing, and the reflectance can be 90% or more.

As shown in FIG. 1 (a), the transparent dielectric thin film 12a is formed before and after the ITO thin film 12b to be the counter electrode.
If 12c is formed to have a three-layer structure, the reflectance can be made smaller than that in the case of two layers, and the antireflection effect over a wide wavelength band can be realized. The conditions of the refractive index and the film thickness in this case are as follows.

[0073]

[Equation 10]

[0074]

[Equation 11]

[0075]

[Equation 12]

[0076]

[Equation 13]

N ₃ is the refractive index of the thin film formed between the ITO thin film and the liquid crystal layer, and d ₃ is the film thickness of the thin film formed between the ITO thin film and the liquid crystal layer. Other symbols are the same as those in (Equation 5) to (Equation 8).

Even under the above condition numbers, the wavelength λ
In the case of the non-reflection condition in (1), when the reflection is reduced in a wide wavelength band, it is preferable to satisfy the conditions of (Formula 10) and (Formula 11) rather than the condition of (Formula 12) and (Formula 13). Further, since the ITO thin film has a sufficiently low resistance value, it is desirable that at least the physical film thickness is 100 nm or more. From this point as well, the optical film thickness n _{2 of the} ITO thin film is
The conditions of (Equation 10) and (Equation 11) with which the condition of d ₂ is λ / 2 are preferable.

The antireflection electrode 12 comprises a first dielectric thin film 12a, an ITO thin film 12b, and an ITO thin film 12b in this order from the counter electrode substrate 14 side.
It has a three-layer structure composed of the second dielectric thin film 12c,
The ITO thin film 12b has an optical film thickness of λ / 2, and the first dielectric thin film 12a and the second dielectric thin film 12c each have an optical film thickness of λ / 4.

Si as the dielectric thin films 12a and 12c
An example of the structure using O is shown in (Table 3), and its spectral reflectance is shown in (FIG. 19). As can be seen from (FIG. 19), according to the configuration of (Table 3), it is possible to realize the characteristic of the reflectance of 0.1% or less over the wavelength bandwidth of 200 nm or more, and to obtain the extremely high antireflection effect. In addition, (Fig. 1
In 9), the upper part of the explanatory text of the graph is the dielectric thin film 1
The material used for 2a, the ITO thin film 12b in the middle, and the dielectric thin film 12c in the lower.

[0081]

[Table 3]

The refractive index of the first dielectric thin film 12a and the second dielectric thin film 12c is preferably 1.60 or more and 1.80 or less. Although SiO was used in all of the examples of (Table 3), one or both of the dielectric thin films was replaced with Al.
Any of ₂ O ₃ , Y ₂ O ₃ , MgO, CeF ₃ , WO ₃ , and PbF ₂ may be used.

Table 4 shows a case where the first dielectric thin film 12a and the second dielectric thin film 12c are made of Y ₂ O ₃ . The spectral reflectance is shown in (FIG. 20). In addition,
Y ₂ O ₃ has a refractive index of 1.78 to 1.8 depending on vapor deposition conditions.
About 8 can be manufactured.

[0084]

[Table 4]

The spectral reflectance when Y ₂ O ₃ is used for the dielectric thin films 12a and 12b tends to be slightly higher for B light and R light than in the case of Al ₂ O ₃ .

Similarly, (Table 5) shows the first dielectric thin film 12
The case where a is SiO and the second dielectric thin film 12c is Y ₂ O ₃ is shown. The spectral reflectance is shown in (FIG. 20). It realizes an extremely excellent antireflection effect of 0.1% or less over the entire visible light region.

[0087]

[Table 5]

Further, (Table 6) shows the first dielectric thin film 12
The case where a is Al ₂ O ₃ and the second dielectric thin film 12c is SiO is shown. The spectral reflectance is shown in (FIG. 20). In the R light and B light regions, the reflectance exceeds 0.5% and cannot be said to be appropriate.

[0089]

[Table 6]

As described above, by forming the dielectric thin films 12a and 12c in three layers on both surfaces of the ITO thin film 12b, a reflected light preventing effect can be provided. Compared to the two-layer structure shown in FIG.
The three-layer structure (a)) has a higher antireflection effect over the entire visible light region.

If the polymer dispersed liquid crystal layer 15 and the ITO thin film are in direct contact with each other, the polymer dispersed liquid crystal layer 15 is likely to deteriorate. It is considered that this is because impurities and the like in the ITO thin film are eluted into the liquid crystal layer 15. IT as in the three-layer structure described above
When the dielectric thin film 12c is formed between the O thin film 12b and the liquid crystal layer 15, the liquid crystal layer 15 is not deteriorated. In particular, when the dielectric thin film 12c was Al ₂ O ₃ or Y ₂ O ₃ , it was good.

When the dielectric thin film 12c is made of SiO, the refractive index of SiO tends to decrease. It is considered that this is because oxygen atoms such as H ₂ O and O ₂ contained in a trace amount in the liquid crystal layer 15 are bonded to SiO, and SiO is changed to SiO ₂ . In that sense, the configurations of (Table 3) and (Table 6) are not suitable. However, SiO does not change to SiO ₂ in a short period of time and can be practically used in many cases. The structure of the antireflection electrode 12 or 25 is as shown in FIG.
It can be applied to the electrode 107 shown in 0).

Reference numeral 20 is a light absorbing thin film formed in the peripheral portion of the reflective electrode. FIG. 2 is a plan view of the reflective electrode 18 when viewed from above. The light absorption thin film is formed on the peripheral portion of the reflective electrode and the connection terminal 19. The connection terminal 19 has a concave shape and does not reflect light straight. Therefore, a light absorbing film is formed to improve the display contrast.

As a method of forming the light absorbing thin film 20, there is a method of depositing a film by sputtering or the like and patterning the film. In addition, after forming the reflective electrode 18, a light absorbing resin is applied on the entire surface and filled between the resin reflective electrodes 18,
Examples include a method of polishing the surface of the reflective electrode to remove only the resin on the reflective electrode 18. The light absorption thin film 20 does not need to be accurately patterned. Even if some uncoated areas occur, the light absorption effect is sufficient.

Examples of materials used for the light absorption thin film 20 include PrMnO ₃ film formed by sputtering, phthalocyanine film formed by plasma polymerization, and the like.

In addition, the light absorbing material for forming the light absorbing film 20 may be any material as long as it has high electric insulation and does not adversely affect the liquid crystal layer 15. For example, a black dye or pigment dispersed in resin may be used, or gelatin or casein may be dyed with a black acid dye like a color filter. As an example of the black dye, it is possible to use a single fluorane dye that becomes black, and to use, or it is possible to use oriented black in which a green dye and a red dye are mixed.

The above materials are all black materials,
When the display panel of the present invention is used as a light valve of a projection display device, it is not limited to this. The projection display device has three display panels that modulate light of three colors of R, G, and B, respectively. The light absorbing film 20 of the display panel that modulates the R light may absorb the R light.
That is, in order to absorb a specific wavelength, for example, a light absorbing material for a color filter may be used after being improved so as to obtain a desired light absorbing characteristic. Basically, similarly to the above-mentioned black absorbing material, it is possible to use a material in which a natural resin is dyed with a dye or a dye is dispersed in a synthetic resin. The range of selection of the dye is wider than that of the black dye, and an appropriate one selected from azo dyes, anthraquinone dyes, phthalocyanine dyes, triphenylmethane dyes, and the like, or a combination of two or more thereof may be used.

Many black dyes adversely affect the liquid crystal layer 15. Therefore, its use is not preferable. Therefore, it is preferable to employ a dye capable of absorbing a specific wavelength as a dye contained in the light absorbing thin film as described above.

It is easy to adopt in a projection type display device using three display panels for R light, B light and G light as light valves. In other words, for the color of the modulated light,
A dye having a complementary color relationship may be contained in the light absorbing thin film. The complementary color relationship is, for example, yellow for B light. The light absorption thin film colored in yellow absorbs B light.
Therefore, the display panel that modulates the B light forms the yellow light absorbing thin film 20.

There are two major effects of forming the light absorption thin film 20. The effect (FIG. 3) and (FIG. 4)
Will be explained. The first effect is an improvement in display contrast. As shown in (FIG. 3), the incident light A hits the water droplet liquid crystal 173 and is scattered, and the traveling direction can be seen. Part of the light is reflected by the source signal line 23 and returns to the liquid crystal layer 15 again. The returned light strikes the water droplet liquid crystal again and is emitted from the counter electrode plate 14. Light emitted from the counter electrode substrate 14 and having an angle within a predetermined range is condensed by a projection lens and projected on a screen (not shown). That is, the black display level becomes high and the display contrast becomes poor.
When the liquid crystal layer 15 is in the scattering state, the incident light A is the counter electrode substrate 1
It is desirable that the light is not emitted from No. 4. If the light absorption film 20b is provided as shown in FIG. 4, the incident light A is absorbed.
Therefore, the display contrast is improved. The second effect is prevention of the photoconductor phenomenon of the TFT 16. The photoconductor phenomenon is a phenomenon in which when the semiconductor layer of the TFT 16 is irradiated with light, it is photoexcited and the TFT is turned on. If the TFT is not turned off, the electric charge cannot be retained between the reflective electrode 18 and the counter electrode.
5 is not in a transparent state and white display cannot be performed. Incident light B shown in FIG. 3 is reflected between the source signal line 23 and the reflective electrode 18 and reaches the TFT 16. When the TFT 16 is irradiated with light, the above-mentioned photoconductor phenomenon occurs. If there is a light absorption thin film 20a as shown in (FIG. 4),
The incident light B is blocked and the photoconductor phenomenon does not occur.

FIG. 1 shows an example of a reflective display panel. The light absorption thin film and the antireflection electrode described in (FIG. 1) can also be used in a photo-writing type display panel. FIG. 10 is a configuration diagram of an optical writing type display panel. On the glass substrate 102, a conductive thin film 103, a photoconductive layer 104 made of amorphous silicon, and a light shielding film 10 are formed.
5, the dielectric mirror 106 is sequentially laminated. The light absorption thin film 101 is formed on the dielectric mirror 106. On the other hand, the antireflection electrode 10 is formed on the counter electrode substrate 108.
7 are formed. An alternating current is applied between the conductive thin film 103 and the antireflection electrode 107, and the state of voltage application to the liquid crystal layer 15 changes depending on the photoexcited state of the photoconductive layer 104.

The antireflection electrode 107 shown in FIG. 10 has the same structure as the antireflection electrode 12 or 25 shown in FIG. 1 and the same effect. Similarly, the light absorption thin film 101 has the same structure as the light absorption thin film 20 (FIG. 1).

The light absorption thin film 101 is formed in a stripe shape as shown in FIG. In FIG. 11, the H direction is the horizontal direction of the screen, and the V direction is the vertical direction of the screen. If the light absorption thin film 101 is formed in a stripe shape, light leakage in the lateral direction can be prevented. The formation pitch of the light absorption thin film 101 preferably corresponds to the width of one pixel. Light absorbing thin film 10
No. 1 is more effective in preventing light leakage when formed in a matrix like a black matrix. However, since the light-absorbing thin film 101 is not formed to reflect light at the location where it is formed, if it is formed in a matrix, it becomes difficult to support multi-scan display. One of the major characteristics of the optical writing type display panel is that it can perform multi-scan. (Figure 10)
With such a stripe shape, it is difficult to change the screen size in the H direction, but it is possible to change the screen size in the V direction.

FIG. 5 is a sectional view of the transmissive display panel of the present invention. Reference numeral 12 is a counter electrode. However, it is not necessary to adopt the antireflection electrode structure as in (FIG. 1).
A pixel electrode 51 made of an ITO thin film is formed on the array substrate 13.
While the black matrix 52 is formed on the counter electrode substrate 12. The black matrix 52 is usually formed using Cr. Source signal line 3
A light absorbing thin film 53 is formed on the signal lines such as 2 and the black matrix. The material for forming the light absorption thin film 53 has the structure described in (FIG. 1), and the material and the like are also the same. The color of the light absorbing thin film is preferably a color that is complementary to the color of light that enters the liquid crystal layer 15.

Consider the effect of the display panel of the present invention shown in FIG. (FIG. 6) and (FIG. 7) are explanatory views for explaining the effect. FIG. 6 shows the structure of a conventional display panel in which the light absorption thin film 53 is not formed, and FIG. 7 shows the structure of the display panel of the present invention in which the light absorption thin film is formed.

Consider the rays A to E as shown in FIG. The light ray A is light that is scattered by the water droplet liquid crystal 173 and returns to the incident light side. The light ray B is light that is scattered by the liquid crystal in the form of water droplets and is also emitted to the emission side. The light ray C is light that is reflected by the black matrix 52 and returns to the incident side. The light ray D is light reflected by the black matrix 52 and leaked to the emission side. The light ray E is also the light reflected by the source signal line 23 and leaking to the emission side. That is, the light rays B, D, and E become leakage light when the light modulation layer 15 is scattered. Since the black matrix 53 and the signal line 23 are formed of a metal thin film, the reflectance is relatively high. Therefore, there is a large amount of light that is reflected by the portion and is also leaked to the emission side. The light leaked to the exit side when the liquid crystal layer 15 is in the scattering state reduces the display contrast.

In recent years, the pixel size has been affected by miniaturization,
Along with this, the area occupied by one pixel of the black matrix is also increasing. As an example, when the panel size is 3 inches, the black matrix occupies about 70% of one pixel in the 300,000 pixel class. There is also a predicted value of 90% in the 1 million pixel class.

As described above, the black matrix 52 occupies a very large proportion, and therefore the light scattered in the liquid crystal layer 15 is reflected again by the black matrix 52 and is output to the emission side, thereby lowering the contrast. This is a big issue. Another problem is that the light reflected by a black matrix or the like enters adjacent pixels or the like to blur the pixel outline, and further reduce the contrast of the entire display area. Similarly, the source signal line 2
3, the light reflected by the gate signal line (not shown), the TFT (not shown), etc. cannot be ignored.

As shown in FIG. 7, when the light absorption thin film 53 is formed, the incident light D is scattered by the water droplet liquid crystal 173 and a part of the light D enters the light absorption thin film 53b. The light is absorbed by the light absorption thin film 53b. Further, the incident light E also scatters upon the water droplet liquid crystal 173, and a part of the incident light E is incident on the light absorption film 53 a formed on the source signal line 23 and absorbed. Therefore, the light output to the emission side can be reduced.

A problem of the display panel using the polymer-dispersed liquid crystal is a reduction in display contrast due to the light reflected at the interface between the array substrate and the counter electrode substrate with the air.
For example, it is light that is reflected by the interface of the substrate 14 with the air and the black matrix 52 and is incident on the liquid crystal layer 15 again like the incident light F of (FIG. 8). In order to prevent the incident light F, when the display panel 121 is a transmissive display panel, a transparent plate 93a may be provided on the display panel as shown in FIG.
Bond 93b. In the case of a reflective display panel (Fig. 1
As shown in 3), the transparent plate 93b is adhered to the incident light side.

The transparent plates 93a and 93b are light-transmissive and thick plates, and more specifically, they are cylindrical or quadrangular prismatic glass plates having a diameter not less than the maximum diameter d of the effective display area of the display panel. is there. Besides, a transparent resin such as an acrylic resin or a polycarbonate resin can be used, and these are relatively inexpensive and can easily be produced in any shape. It is also preferable because it is light in weight. The transparent substrate 93 is optically connected by the optical coupling agent 92. Optical binder 92
Specific examples of the transparent resin include transparent silicone resins, UV-curable adhesives, epoxy-based transparent adhesives, and ethylene glycol. It is preferable that the optical coupling agent has a refractive index of about 1.4 to 1.5 and a difference in refractive index from the glass substrate such as the counter electrode substrate of the display panel 121 or 131 is within 0.05.

Black paint 1 is applied to the invalid display surface of the transparent substrate 93.
22 is applied so that the light reflected at the interface between the air and the transparent substrate 93 can be absorbed.

When the transparent plate 93b and the counter electrode substrate of the display panel or the transparent substrate 93a and the array substrate of the display panel are added together, the center thickness t is, when the refractive index is n and the maximum diameter of the effective display area of the liquid crystal panel is d, Make sure to satisfy the following formula.

[0114]

[Equation 14]

The reason why (Equation 14) must be satisfied is described in the specification of Japanese Patent Application No. 4-145277, and therefore its explanation is omitted. It should be noted that the center thickness t is set by making the surface of the glass plate in contact with air concave, that is, by forming a concave lens shape.
Can be shortened. This matter also applies to Japanese Patent Application No. 4-145.
Since it is described in the specification of No. 277, its explanation is omitted.

As described above, as shown in (Equation 14), the center thickness d of the transparent plate 93 is set to a predetermined value or more, or the one surface of the transparent substrate 93 is made to be a concave surface, whereby the display panel is formed. The light emitted from the liquid crystal layer 15 and reflected at the interface between the transparent plate 93 and the air is absorbed by the light absorbing paint 122. Therefore, it does not return to the liquid crystal layer 15 of the display panel again.

Although the transparent plate 93 is connected to the display panel by the optical coupling agent 92, the invention is not limited to this, and the thickness of the counter electrode substrate or the array substrate of the display panel satisfies (Equation 14). If there is a transparent substrate 93
Clearly there is no need to use.

As shown in FIG. 9, the incident light A hits the water droplet liquid crystal 173 and is scattered. The scattered light A ₁ is reflected by the light incident surface 94b, enters the black paint 122, and is absorbed. If the transparent substrate 93 is not provided as in the conventional display panel, it is reflected at the interface between the counter electrode substrate 14 and the air, and the reflected light A ₂
Then, the light enters the liquid crystal layer 15 again. This raises the brightness of the liquid crystal layer 15 when the voltage is not applied to the liquid crystal and is off, thereby lowering the display contrast. By arranging the transparent substrate 93b as shown in (FIG. 9), the reflected light A ₂ disappears. Therefore, the display contrast is lower than that in the first embodiment.

The cause of lowering the display contrast is TF.
There is a T16 leak. This is because light enters the semiconductor layer of the TFT 16 and is excited by the light to generate a photoconductor phenomenon. In order to prevent this, in the transparent display panel of the present invention, the light shielding film 91 is formed on the TFT 16. But this alone is not perfect. This is because the incident light B may be scattered by the liquid crystal layer 15 and return. In the display panel of the present invention, since the transparent substrate 93a is arranged, the scattered light B ₁ is reflected at the interface 94a between the transparent substrate 93a and the air, and the black paint 1
It is incident on 22 and is absorbed. Therefore, again TFT1
I will never come back to 6. Without the transparent substrate 93a, the light is reflected at the interface between the array substrate 13 and the air, and becomes reflected light B ₂ and returns to the TFT 16. Therefore, in the conventional configuration, the photoconductor phenomenon of the TFT occurs due to the reflected light B ₂ , the leak of the TFT 16 occurs, and the display contrast becomes low. Since the second embodiment can completely prevent it, the display contrast can be increased.

In the first and second embodiments,
The black matrix 52 as viewed from the array substrate 13 side has a specular surface so that it can reflect light. Since the incident light that hits the black matrix 52 is reflected, the display panel is not heated. If the upper and lower positions of the black matrix 52 are reversed by the light absorption thin film 53, the light absorption thin film 53 absorbs incident light and heats and deteriorates the display panel.

The projection type display device of the present invention will be described below with reference to the drawings. FIG. 14 is a configuration diagram of an embodiment of the projection type display device of the present invention. However, components that are unnecessary for the description are omitted. In (Fig. 14),
Reference numeral 141 denotes a condensing optical system in which a concave mirror and a metal halide lamp or a xenon lamp as a light generating means are arranged. It is desirable to use a lamp having an arc length as short as possible. Generally, the arc length of a xenon lamp is 2 mm or less, which is sufficient for the liquid crystal projection television of the present invention. However, it has a short life. 250 metal halide lamps
It is of W class and has an arc length of about 6 mm. This is not preferable because the arc length is too long. Arc length is 5 mm
The following are preferred. Short arc arc metal halide lamps are sold as long as they have low power consumption. As an example, 120W from Iwasaki Electric Co., Ltd., arc length 3m
There are some m. The liquid crystal projection television of the present invention uses a metal halide lamp, and the arc length of the lamp is 5 m.
m or less was used. The concave mirror is designed to a proper value according to the arc length of the lamp. The same applies to the F value of the projection lens. As an example, if the arc length is 5 mm, the F value of the projection lens is set to about F7, if the arc length is 4 mm, the F value of the projection lens is set to about F8, and if it is 3 mm, the F value is set to about F10.

Reference numeral 142 is a UVIR cut filter which reflects infrared rays and ultraviolet rays and transmits only visible light. Further, 143a is a dichroic mirror that reflects B light (hereinafter referred to as BDM), 143b is a dichroic mirror that reflects G light (hereinafter referred to as GDM),
Reference numeral 143c is a dichroic mirror (hereinafter referred to as RDM) that reflects R light. The arrangement of BDM 143a to RDM 143c is not limited to the order shown in FIG. Needless to say, the final RDM 143c may be replaced with a total reflection mirror.

Reference numeral 144 is a display panel of the present invention. In the projection display device of the present invention, the display panel of the present invention is used as a light valve. It should be noted that the display panel that modulates the R light has a larger water droplet liquid crystal particle size than other display panels,
Alternatively, the liquid crystal film is made thicker. This is because the longer the wavelength of light, the lower the scattering characteristics and the lower the contrast. The particle size of the water-drop liquid crystal can be controlled by controlling the ultraviolet light during polymerization or by changing the material used. The liquid crystal film thickness can be adjusted by changing the bead diameter of the liquid crystal layer 15. 14
Reference numeral 5 is a lens, 147 is a projection lens, and 146 is an aperture as a diaphragm. 145, 146 and 1
47 forms a projection optical system. The aperture is illustrated for the purpose of explaining the operation of the projection display device. Since the aperture defines the converging angle of the projection lens, it may be considered as included in the function of the projection lens. That is, if the F value is large, it can be considered that the hole diameter of the aperture is small. In order to obtain a high contrast display, the larger the F value of the projection lens, the better. However, the larger the brightness, the lower the brightness of white display.

The operation of the projection display device of the present invention will be described below. Since the R, G, and B light modulation systems have almost the same operation, the B light modulation system will be described as an example. First, white light is emitted from the condensing optical system 141, and the B light component of this white light is emitted from the BDM 14
It is reflected by 3a. This B light is displayed on the display panel 144a.
Incident on. The display panel 144a (see FIG. 17 (a))
As shown in (b), the light applied is modulated by controlling the scattering and transmission state of the incident light by the signal applied to the pixel electrode.

The scattered light is shielded by the aperture 146a, and conversely, the parallel light or the light within a predetermined angle is emitted by the aperture 14a.
Pass 6a. The modulated light is enlarged and projected on a screen (not shown) by the projection lens 147a. As described above, the B light component of the image is displayed on the screen. Similarly, the display panel 144b modulates the G light component light, and the display panel 144c modulates the R light component light, so that a color image is displayed on the screen. In addition,
When a transparent plate is adhered to the display panel 144 and one surface of the transparent plate has a plano-concave lens shape, the projection optical system is configured in consideration of refraction of the concave lens.

Although FIG. 14 shows a method of enlarging and projecting on a screen by three projection lenses 147, there is also a method of enlarging and projecting with one projection lens. The block diagram is shown in FIG. Reference numeral 157 is a display panel of the present invention. Here, for ease of explanation, 157G is a display panel for displaying an image of G light, 157R is a display panel for displaying an image of R light, and 157B is a display panel for displaying an image of B light. Therefore, the wavelengths that are transmitted and reflected by each dichroic mirror are the dichroic mirror 155a.
Reflects R light and transmits G light and B light. The dichroic mirror 155b reflects G light and transmits R light. The dichroic mirror 155d reflects B light and transmits G light and R light.

The light emitted from the metal halide lamp 152 is reflected by the total reflection mirror 153a, and the direction of the light is changed. Next, the UVIR cut filter 154 cuts off the light having wavelengths in the ultraviolet region and the infrared region. The light that has been cut off the ultraviolet rays and infrared rays is reflected by the dichroic mirrors 155a and 155b.
Separation of the three wavelength regions of G and B light, R light to the field lens 156R, G light to the field lens 156
The G light and the B light are incident on the field lens 156b. Each field lens 156 collects each light, and the display panel 1
Reference numeral 57 respectively changes the orientation of the liquid crystal corresponding to the video signal to modulate the light. The R, G, and B lights thus modulated are combined by the dichroic mirrors 157c and 157d, and enlarged and projected on the screen by the projection lens 158.

On the other hand, FIG. 16 shows an example in which the projection display device is constructed by the reflection method. As the light valve, the display panel shown in FIG. 1 or the display panel shown in FIG. 10 is used. The light source 162 is a lamp 162a, a concave mirror 1
62b and a filter 162c. Lamp 162
Reference numeral a is a metal halide lamp, and the concave mirror 162b is made of glass, and has a reflective surface on which a multilayer film for reflecting visible light and reflecting infrared light is vapor-deposited. The visible light included in the light emitted from the lamp 162a is reflected by the reflecting surface of the concave mirror 162b. The reflected light emitted from the concave mirror 162b is emitted after the infrared rays and ultraviolet rays are removed by the filter 162c.

The projection lens 161 comprises a first lens group 161b on the display panel 165 side and a second lens group 161a on the screen side. The first lens group 161b and the second lens group 161b
A plane mirror 163 is arranged between the lens group 161a. The scattered light emitted from the pixel in the center of the screen of the display panel 165, after passing through the first lens group 161b, is approximately half incident on the plane mirror 163 and the rest is not incident on the plane mirror 163, and the second lens group is not incident. It is incident on 161a. The radiation of the reflecting surface of the plane mirror 163 is the projection lens 16
The optical axis 166 of 1 is inclined by 45 °.

The light from the light source 162 is reflected by the plane mirror 163, passes through the first lens group 161b, and enters the display panel 165. The reflected light from the display panel 165 is
The light passes through the first lens group 161b and the second lens group 161a in this order and reaches the screen 167. Projection lens 161
Light rays that exit the center of the diaphragm and travel toward the display panel 165 are made substantially vertical to the liquid crystal layer 15, that is, telecentric. Here, for ease of explanation, 165b is a display panel for modulating G light, 165
It is assumed that c is a display panel that modulates B light and 165a is a display panel that modulates R light.

In FIG. 16, reference numeral 164 designates a dichroic mirror, which serves both as a color combining system and a color separating system. The white light emitted from the light source is a plane mirror 1.
It is bent by 63 and enters the first group of the projection lens 161. At this time, unnecessary B light and R light are cut by the filter 162c. The band of the filter 162c has a half-width value of 430 nm to 690 nm. Hereinafter, when describing the band of light, it is expressed by a half width. The dichroic mirror 164a reflects G light and reflects R light and B light.
Allows light to pass through. G light is dichroic mirror 164c
The band is limited by and is incident on the display panel 164b. The band of G light is set to 510 to 570 nm.

On the other hand, the dichroic mirror 164b is B
Reflects light and transmits R light. B light is display panel 16
The R light is incident on the display panel 165a at 5c. The band of incident B light is 430 nm to 490 nm, and the band of R light is 600 nm to 690 nm. An optical image is formed on the display panel as a change in the scattering state according to each video signal. The optical image formed on the display panel is color-synthesized by the dichroic mirrors 164a and 164b, and the projection lens 1
It is incident on 61 and is enlarged and projected on the screen 167.
The R, G, and B light bands have almost the same values in the projection display device of the present invention.

When a reflective display panel is used, the contrast is better than that of the transmissive display panel, and the pixel aperture ratio is high, so that high-luminance display can be performed. Moreover, since there is no obstacle on the back surface of the display panel, the panel can be easily cooled. For example, forced air cooling from the back surface can be easily performed, and a heat sink or the like can be easily attached to the back surface.

[0134]

As described above, according to the present invention, by forming the light absorbing thin film on the surface of the black matrix, it is possible to absorb the light which is diffusely reflected by the liquid crystal layer at the time of scattering, and the contrast of the display panel. Can be improved. Further, by disposing the glass plate, the TFT is not irradiated with light, and the occurrence of the photoconductor phenomenon of the TFT can be prevented. Also, the display contrast can be improved.

Further, by using the polymer-dispersed liquid crystal, a polarizing plate becomes unnecessary, and a high-brightness display three times or more as high as that of the TN liquid crystal display panel can be realized. This means that not only the light utilization efficiency can be improved, but also the conversion of light into heat can be greatly reduced, and the deterioration of the panel performance due to heating can be prevented. This is very effective when the intensity of light incident on a single display panel is as large as tens of thousands of lux like a projection display device.

In the projection type display device of the present invention, the display panel of the present invention is used as a light valve.
High-luminance display can be realized, and it can be used for large screens of 200 inches or more. Further, since the liquid crystal film thickness of the display panel and the average particle diameter of the water droplet liquid crystal are made appropriate according to the wavelength of the modulated light, it is possible to realize image display with good white balance and contrast.

[Brief description of drawings]

FIG. 1 is a sectional view of a display panel of the present invention.

FIG. 2 is a plan view of a display panel of the present invention.

FIG. 3 is an explanatory diagram of a display panel of the present invention.

FIG. 4 is an explanatory diagram of a display panel of the present invention.

FIG. 5 is a sectional view of a display panel according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a display panel of the present invention.

FIG. 7 is an explanatory diagram of a display panel of the present invention.

FIG. 8 is an explanatory diagram of a display panel of the present invention.

FIG. 9 is an explanatory diagram of a display panel of the present invention.

FIG. 10 is a configuration diagram of a display panel in another embodiment of the present invention.

FIG. 11 is a partial plan view of a display panel of the present invention.

FIG. 12 is a configuration diagram of another embodiment of the display panel of the present invention.

FIG. 13 is a configuration diagram of a display panel in another embodiment of the present invention.

FIG. 14 is a configuration diagram of an embodiment of a projection display device of the present invention.

FIG. 15 is a configuration diagram of a projection display device according to another embodiment of the present invention.

FIG. 16 is a configuration diagram of a projection display device according to another embodiment of the present invention.

FIG. 17 is an explanatory diagram of the operation of the polymer dispersed liquid crystal.

FIG. 18 is an explanatory diagram of a projection display device of the present invention.

FIG. 19 is an explanatory diagram of a projection display device of the present invention.

FIG. 20 is an explanatory diagram of a projection display device of the present invention.

[Explanation of symbols]

11, 12 Antireflection film 12, 25, 171 Counter electrode 13 Array substrate 14 Counter substrate 15 Liquid crystal layer 16 TFT 17 Insulating layer 18 Reflective electrode 19 Connection part 20 Light absorbing film 23 Source signal line 51 Pixel electrode 52 Black matrix 53a, 53b Light absorbing film 91 Light shielding film 92a, 92b Optical coupling agent 93a, 93b Transparent plate 94a, 94b Interface 101 Light absorbing film 102 Substrate 103, 107 Transparent electrode 104 Photoconductive layer 105 Light shielding film 106 Dielectric mirror 108 Glass substrate 121 Liquid crystal panel 122 black paint 141, 152 condensing optical system 142, 154, 162c UVIR cut filter 143a, 143b, 143c, 155a, 155b,
155c, 164a, 164b, 164c Dichroic mirrors 144a, 144b, 144c, 157R, 157G,
157B, 165a, 165b, 165c Liquid crystal panel 145a, 145b, 145c Lens 146a, 146b, 146c Aperture 147a, 147b, 147c, 158, 161 Projection lens 153a, 153b, 153c, 163 Mirror 156R, 156G, 157B Field lens 162a Metal lens 162a 162b concave mirror 172 pixel electrode 173 water droplet liquid crystal 174 polymer

Claims (23)

[Claims] 1. A first and a second substrate, at least one of which has a light transmitting property, and a light modulation layer sandwiched between the first and the second substrate and forming an optical image as a change of a light scattering state. And a light absorbing means formed on at least one of the first substrate and the second substrate and on a surface in contact with the light modulation layer. 2. The light absorbing means is a thin film containing a dye,
The display panel according to claim 1, wherein the dye is a dye that absorbs light modulated by the light modulation layer. 3. The display panel according to claim 1, wherein the light modulation layer is a polymer-dispersed liquid crystal. 4. The display panel according to claim 2, wherein the dye is a dye having a color complementary to the color of the light modulated by the light modulation layer. 5. A first substrate on which a first electrode having light transmissivity is formed, a second substrate having a plurality of reflective electrodes arranged in a matrix, the first electrode and the reflection. A display panel comprising: a polymer-dispersed liquid crystal layer sandwiched between electrodes; and a light-absorbing thin film formed between adjacent reflective electrodes. 6. The display panel according to claim 5, wherein the light absorbing thin film contains a dye that absorbs light modulated by the polymer dispersed liquid crystal layer. 7. The first electrode comprises a first dielectric thin film, an ITO thin film for applying an electric field to the polymer dispersed liquid crystal, and a second electrode.
The dielectric thin films are sequentially laminated, and the refractive index n ₁ of the first and second dielectric thin films is 1.6 or more and 1.8 or more.
And the optical film thickness of the dielectric thin film is approximately λ /
4 (λ is the design dominant wavelength of light), the refractive index n ₂ of the ITO thin film is 2.0 or less, the optical thickness of the ITO thin film is approximately λ / 2, and an electric field is applied. Assuming that the refractive index of the polymer-dispersed liquid crystal when not in use is n ₃ , n ₂ > n ₁ >
n ₃ and the first and second dielectric thin films are composed of dialuminum trioxide (Al ₂ O ₃ ), yttrium trioxide (Y ₂ O ₃ ), silicon monoxide (SiO), and trioxide. Tungsten (WO ₃ ), cerium trifluoride (Ce
F ₃ ), magnesium oxide (MgO), lead difluoride (Pb
The display panel according to claim 5, which is a thin film of any one of F ₂ ). 8. The first electrode has a structure in which a dielectric thin film and an ITO thin film for applying an electric field to polymer dispersed liquid crystal are sequentially laminated on a first substrate, and the dielectric thin film is refracted. The index n ₁ is 1.5 or more and 1.7 or less, the optical thickness of the dielectric thin film is approximately λ / 4 (λ is the design dominant wavelength of light), and the refractive index n _{2 of the} ITO thin film is Is 2.0 or less, the optical film thickness of the ITO thin film is approximately λ / 2, and n ₂ > when the refractive index of the polymer-dispersed liquid crystal when no electric field is applied is n _3. There is a relationship of n ₁ > n _3, and the dielectric thin film includes dialuminum trioxide (Al ₂ O ₃ ), silicon monoxide (SiO), and tungsten trioxide (W).
O _3), trifluoride cerium (CeF _3), trifluorochloroethylene lanthanum (LaF _3), trifluoride neodymium (NdF ₃₎ display panel of claim 5, wherein it is a one of a thin film of. 9. A first substrate having a plurality of pixel electrodes arranged in a matrix and a signal line for transmitting a signal applied to the pixel electrode; and a first substrate formed corresponding to the pixel electrode position. A second substrate having a light-shielding pattern, a polymer dispersed liquid crystal sandwiched between the light-shielding pattern and the pixel electrode, and a light-absorbing thin film formed on at least one of the light-shielding pattern and the signal line. Display panel characterized by. 10. The display panel according to claim 9, wherein the light absorbing thin film contains a dye that absorbs light modulated by the polymer dispersed liquid crystal layer. 11. A first substrate on which a first electrode having a light-transmitting property is formed, a second electrode, a photoconductive layer, a light-shielding layer, and a light-reflecting layer composed of a dielectric thin film are sequentially formed. Second stacked
Substrate, a polymer dispersed liquid crystal layer sandwiched between the first electrode and a light reflecting layer, and a light absorbing thin film formed on at least one of the first electrode and the light reflecting layer. Display panel characterized by. 12. The display panel according to claim 11, wherein the light absorbing thin film is formed in a stripe pattern and contains a dye that absorbs light modulated by the polymer dispersed liquid crystal layer. 13. A first device, at least one of which is light transmissive.
And a second substrate, a light modulation layer sandwiched between the first and second substrates and forming an optical image as a change in the light scattering state, and at least the first substrate and the second substrate. A display panel comprising a light absorbing means formed on one of the substrates and on a surface in contact with the light modulating layer; one light generating means; and a light guiding means for guiding the light emitted by the light generating means to the display panel. 1. A projection display device comprising: a light source unit 1 and a projection unit for projecting light modulated by the display panel. 14. The first light absorbing means is a thin film that absorbs the light incident on the light modulation layer, and contains a dye having a complementary color relationship with the color of the light. The projection display device described. 15. The light modulation layer is composed of a polymer-dispersed liquid crystal,
14. The projection display device according to claim 13, wherein the thin film of the liquid crystal has a thickness of 5 μm or more and 25 μm or less. 16. At least one dielectric thin film and I
A first substrate having a light-transmitting first electrode formed of a stack of TO thin films, a second electrode, a photoconductive layer, a light-shielding layer, and a light-reflecting layer composed of a dielectric thin film, A second substrate that is sequentially stacked, a polymer-dispersed liquid crystal layer sandwiched between the first electrode and a light reflecting layer, and a second substrate formed on at least one of the first electrode and the light reflecting layer. A display panel comprising one light absorbing means, one light generating means, a light separating means for separating the light emitted by the light generating means into three optical paths of red light, blue light and green light; A projection display device comprising: a projection unit that projects light modulated by a panel, wherein the display panel is arranged in each of the three optical paths. 17. The first light absorbing means is a thin film containing a dye, and the dye has a function of absorbing light modulated by the polymer dispersed liquid crystal layer. Projection display device. 18. The first electrode has a structure in which a first dielectric thin film, an ITO thin film for applying an electric field to the light modulation layer, and a second dielectric thin film are sequentially stacked. The refractive index n ₁ of the first and second dielectric thin films is 1.6 or more and 1.8 or less, and the optical thickness of the dielectric thin film is approximately λ / 4.
(Λ is the designed main wavelength of light), the refractive index n ₂ of the ITO thin film is 2.0 or less, the optical thickness of the ITO thin film is approximately λ / 2, and an electric field is applied. Assuming that the refractive index of the polymer-dispersed liquid crystal when not present is n ₃ , n ₂ > n ₁ > n ₃
And the first and second dielectric thin films have the following relationship:
Dialuminum trioxide (Al ₂ O ₃ ) Yttrium trioxide (Y ₂ O ₃ ), Silicon monoxide (SiO), Tungsten trioxide (WO ₃ ), Cerium trifluoride (CeF ₃ ), Magnesium oxide (MgO) The display panel according to claim 16, wherein the display panel is a thin film of any one of lead difluoride (PbF ₂ ). 19. At least one or more dielectric thin films, and I
A first substrate having a first electrode having a light-transmitting property, which is formed by stacking a TO thin film, a second substrate having a plurality of reflective electrodes arranged in a matrix, the first electrode and the A display panel comprising a polymer dispersed liquid crystal sandwiched between reflective electrodes and a first light absorbing means formed on the periphery of the reflective electrode, one light generating means, and the light generating means emitting light. A light splitting unit that splits the generated light into three light paths of red light, blue light, and green light; and a projection unit that projects the light modulated by the display panel. A projection type display device characterized by being arranged. 20. The first light absorbing means is a thin film containing a dye, and the dye has a function of absorbing light modulated by the polymer dispersed liquid crystal layer. Projection display device. 21. The first electrode has a structure in which a first dielectric thin film, an ITO thin film for applying an electric field to the light modulation layer, and a second dielectric thin film are sequentially stacked. The refractive index n ₁ of the first and second dielectric thin films is 1.6 or more and 1.8 or less, and the optical thickness of the dielectric thin film is approximately λ / 4.
(Λ is the designed main wavelength of light), the refractive index n ₂ of the ITO thin film is 2.0 or less, the optical thickness of the ITO thin film is approximately λ / 2, and an electric field is applied. Assuming that the refractive index of the polymer-dispersed liquid crystal when not present is n ₃ , n ₂ > n ₁ > n ₃
And the first and second dielectric thin films have the following relationship:
Thin film of any one of dialuminum trioxide (Al ₂ O ₃ ), yttrium trioxide (Y ₂ O ₃ ), silicon monoxide (SiO), tungsten trioxide (WO ₃ ), and cerium trifluoride (CeF ₃ ). 20. The display panel according to claim 19, wherein: 22. A first substrate having a plurality of pixel electrodes arranged in a matrix and a signal line for transmitting a signal applied to the pixel electrode; and a first substrate formed corresponding to the pixel electrode position. A second substrate having a light-shielding pattern, a polymer-dispersed liquid crystal layer sandwiched between the light-shielding pattern and the pixel electrode, and a light-absorbing thin film formed on at least one of the light-shielding pattern and the signal line. Display panel and one light generating means, light separating means for separating the light emitted by the light generating means into three optical paths of red light, blue light and green light, and the light modulated by the display panel is projected. The projection display device is characterized in that the display panel is arranged in each of the three optical paths. 23. The light absorbing thin film has a function of absorbing light incident on the polymer dispersed liquid crystal layer, and contains a dye having a complementary color relationship with the color of the light. The projection display device described.