JP3231396B2 - Liquid crystal panel and liquid crystal projection television using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection television for mainly projecting an image displayed on a small liquid crystal panel onto a screen in an enlarged manner, and to a liquid crystal panel mainly used for the liquid crystal projection television.

[0002]

2. Description of the Related Art Since liquid crystal panels have many features such as light weight and thinness, research and development have been active. However, there are many problems such as difficulty in increasing the screen. Therefore, in recent years, a liquid crystal projection television that enlarges and projects a display image of a small liquid crystal panel with a projection lens or the like and obtains a display image of a large screen has been attracting attention. At present, a commercially available liquid crystal projection television uses a twisted nematic (hereinafter referred to as TN) liquid crystal panel utilizing the optical rotation characteristics of liquid crystal. An example of a liquid crystal projection television and a liquid crystal panel used in the television are described in “Flat Color Display '91: Nikkei BP Publishing”, pp. 194 to P205.

Hereinafter, a conventional liquid crystal panel will be described. However, unnecessary parts are omitted from the explanation,
The drawing is modeled to make the drawing easier to see. The same applies to the following drawings.

FIG. 7 is an equivalent circuit diagram of an active matrix type liquid crystal panel. One pixel is formed with a thin film transistor (hereinafter, referred to as a TFT) as a switching element for controlling a signal applied to the pixel. The TFT73 performs a operation of the on-off by a signal applied to the gate signal line G ₁ ~G _m, the on state, the signal applied to the source signal line S ₁ to S _n is applied to each pixel. Each pixel has a liquid crystal 75 and a storage capacitor 74 that can be regarded as a capacitor formed between the counter electrode and the pixel electrode. Reference numeral 71 denotes a gate drive IC for applying on / off voltages to the gate signal lines, and reference numeral 72 denotes a source drive IC for applying a video signal to the source signal lines.

FIG. 8 is a sectional view of a conventional liquid crystal panel. The array substrate 82 and the counter electrode substrate 81 are held at an interval of 4 to 6 μm, and a TN liquid crystal 86 is injected between the substrates. The periphery of the display area is sealed with a sealing resin (not shown). 88 is a black matrix (hereinafter referred to as BM) formed of chromium or the like, 83 is a counter electrode formed of a transparent material such as ITO, 85 is a pixel electrode, 8
4 is a thin film transistor (hereinafter referred to as TFT), 87
Reference numerals a and 87b denote alignment films.

Hereinafter, a conventional method for manufacturing a liquid crystal panel will be briefly described. First, alignment films 87a and 87b are applied to the array substrate 82 and the counter electrode substrate 81, respectively, and are subjected to an alignment process by a rubbing process. Thereafter, a sealing resin is applied to the periphery of the array substrate 82 except for the injection port of the TN liquid crystal 86. Further, beads for obtaining a uniform liquid crystal film thickness are sprayed on the counter electrode substrate 81. Next, the counter electrode substrate 81 and the array substrate 82 are bonded to each other. Thereafter, the sealing resin is cured by irradiating or heating with ultraviolet rays. Next, the bonded substrates are placed in a vacuum chamber, and the gap between the array substrate 82 and the counter electrode substrate 81 is evacuated, and then the liquid crystal injection port is immersed in the liquid crystal. Thereafter, when the vacuum in the vacuum chamber is broken, the liquid crystal is injected into the gap from the injection port. Finally, the inlet is sealed to complete.

Hereinafter, a conventional liquid crystal projection television will be described with reference to the drawings. FIG. 9 is a configuration diagram of a conventional liquid crystal projection television. In FIG. 9, reference numeral 91 denotes a condensing optical system, and 92 denotes a UV that transmits infrared rays and ultraviolet rays.
An IR cut mirror, 93a is a blue light reflecting dichroic mirror (hereinafter referred to as BDM), 93b is a green light reflecting dichroic mirror (hereinafter referred to as GDM), 93c is a red light reflecting dichroic mirror (hereinafter referred to as RDM), 94a , 94b, 94c, 96a, 96b, 96
c is a polarizing plate, 95a, 95b and 95c are transmissive TN liquid crystal panels, and 97a, 97b and 97c are projection lens systems.

Hereinafter, the operation of the conventional liquid crystal projection television will be described with reference to FIG. First, white light emitted from the condensing optical system 91 reflects blue light (hereinafter, referred to as B light) by the BDM 93a, and the B light is incident on the polarizing plate 94a. The light transmitted through the BDM 93a is GD
The green light (hereinafter, referred to as G light) is reflected by the M93b to the polarizing plate 94b, and the red light (hereinafter, referred to as R light) is reflected by the RDM 93c to be incident on the polarizing plate 94c. The polarizing plate 94 transmits only one of the longitudinal wave component and the transverse wave component of each color light, and irradiates each liquid crystal panel 95 with the polarization direction of the light aligned. At this time, 50% or more of the light is absorbed by the polarizing plate, and transmitted light is less than half of the incident light.

Each liquid crystal panel modulates the incident light according to a video signal. The modulated light passes through each of the polarizing plates 96a, 96b, and 96c according to the degree of the modulation, and is transmitted to each of the projection lens systems 9a.
7a, 97b, and 97c, and are enlarged and projected on a screen (not shown) by the lens system.

[0010]

As is clear from the above description, in a liquid crystal panel using a TN liquid crystal, it is necessary to use a polarizing plate to convert incident light into linearly polarized light. In addition, a polarizing plate needs to be disposed on the emission side of the liquid crystal panel to detect light modulated by the liquid crystal panel. In other words, before and after the TN liquid crystal panel, a polarizing plate (hereinafter, referred to as a polarizer) for converting light into linearly polarized light and a polarizing plate (hereinafter, referred to as an analyzer) for detecting modulated light are provided. It is necessary to arrange a polarizing plate. The pixel aperture ratio of the liquid crystal panel is 100%,
Assuming that the amount of light incident on the polarizer is 1, the amount of light emitted from the polarizer is 40%, the transmittance of the liquid crystal panel is 80%, and the transmittance of the analyzer is 80%.
4 × 0.8 × 0.8 = about 25%, and only 25% of light can be effectively used. Therefore, only a low luminance image display can be realized with the TN liquid crystal panel.

Most of the light lost by the polarizing plate is absorbed by the polarizing plate and converted into heat. The heat heats the liquid crystal panel by the polarizing plate itself and radiant heat. In the case of a liquid crystal projection television, the amount of light incident on the polarizing plate is tens of thousands lux or more. Therefore, when a TN liquid crystal panel is used in a liquid crystal projection television, the polarizer, the panel, and the like are in a high temperature state,
Causes significant performance degradation in a short period of time.

The TN liquid crystal panel needs to apply an alignment film and perform a rubbing treatment. The rubbing treatment or the like increases the number of processes and causes an increase in manufacturing cost. In recent years, the number of pixels of a liquid crystal panel used for a liquid crystal projection television has increased to 300,000 or more, and the pixel size tends to be finer as the number of pixels increases. The miniaturization of the pixels results in the formation of a large number of irregularities on the signal lines and the TFTs, and rubbing cannot be performed satisfactorily due to the irregularities . Also, miniaturization of the pixel size is 1
The formation area of the TFT and the signal line occupying one pixel is increased, and the pixel aperture ratio is reduced. For example, when 350,000 pixels are formed by a 3 inch diagonal liquid crystal panel, the pixel aperture ratio is about 30%. 10% when 1.5 million pixels are formed
Some estimates are weak. These reductions in the pixel aperture ratio are not limited to lowering the brightness of the display image, and the liquid crystal panel is heated further than the light applied to the area other than the incident light aperture, thereby accelerating the aforementioned performance deterioration.

Further, the TN liquid crystal panel generates a phenomenon of light leakage near signal lines. This is a phenomenon when the liquid crystal panel is used in the normally white mode. When black display is performed, moon-shaped light leakage occurs near the signal line.
This light loss not only significantly lowers the contrast but also lowers the image display quality. In order to prevent this light leakage, the line width of the black matrix must be further increased, which also leads to a decrease in the pixel aperture ratio, and causes a vicious cycle in which the liquid crystal panel is heated. As described above, the display of the conventional TN liquid crystal panel has low brightness, and the panel and the like are heated due to low light use efficiency. Also, when a liquid crystal projection type television was constructed using a TN liquid crystal panel, the performance of the liquid crystal panel and the like deteriorated remarkably.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of conventional liquid crystal panels and projection televisions, and provides a high-brightness, high-quality liquid crystal panel and a liquid crystal projection television that can sufficiently cope with high-vision broadcasting. It is.

[0015]

SUMMARY OF THE INVENTION Since a TN liquid crystal panel uses a polarizing plate or the like, high-luminance display cannot be performed. Therefore, the liquid crystal panel of the present invention comprises a liquid crystal panel using polymer dispersed liquid crystal.

The polymer-dispersed liquid crystal will be briefly described below. The polymer-dispersed liquid crystal is roughly classified into two types depending on the dispersion state of the liquid crystal and the polymer. One is a type in which a liquid crystal in the form of water droplets is dispersed in a polymer. The liquid crystal exists in a discontinuous state in the polymer. Hereinafter, such a liquid crystal is referred to as a PDLC, and a liquid crystal panel using the liquid crystal is referred to as a PD liquid crystal panel. The other type adopts a structure in which a polymer network is stretched around a liquid crystal layer. It looks just like a sponge with liquid crystal. Liquid crystals exist continuously without being in the form of water droplets. Hereinafter, such a liquid crystal is referred to as PNLC.
A liquid crystal panel using the liquid crystal is called a PN liquid crystal panel.
In order to display an image on the two types of liquid crystal panels, scattering and transmission of light are controlled.

PDLC utilizes the property that the refractive index varies in the direction in which the liquid crystal is oriented. In the state where no voltage is applied, the respective liquid crystal droplets are oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer and the liquid crystal, and the incident light is scattered. Here, when a voltage is applied, the alignment directions of the liquid crystals are aligned. If the refractive index when the liquid crystal is aligned in a certain direction is adjusted in advance to the refractive index of the polymer, incident light is transmitted without being scattered.

On the other hand, PNLC uses the irregularity of the alignment of liquid crystal molecules. In an irregular orientation state, that is, in a state where no voltage is applied, incident light is scattered.
On the other hand, when a voltage is applied to make the arrangement state regular, light is transmitted. The above description of the movement of the liquid crystal of PDLC and PNLC is based on a model-based concept. Although the present invention is not limited to one of the PD liquid crystal panel and the PN liquid crystal panel, the PD liquid crystal panel
A description will be given using a liquid crystal panel as an example. Further, PDLC and PNLC are collectively called polymer dispersed liquid crystal, and PD liquid crystal panel and PN liquid crystal panel are collectively called polymer dispersed liquid crystal panel. Liquids containing liquid crystal to be injected into the polymer dispersed liquid crystal panel are collectively referred to as a liquid crystal solution, and a state in which a resin component in the liquid crystal solution is polymerized and cured is referred to as a polymer.

Operation of polymer dispersed liquid crystal (FIG. 10)
This will be briefly described using (a) and (b)). (FIG. 10 (a)
(B) is an explanatory view of the operation of the polymer dispersed liquid crystal panel. In FIGS. 10A and 10B, 101 is an array substrate, 102 is a counter electrode, 103 is a pixel electrode, 104 is a water-drop liquid crystal, 105 is a polymer, and 106 is a counter electrode substrate. A TFT (not shown) or the like is connected to the pixel electrode 103 , and a voltage is applied to the pixel electrode when the TFT is turned on and off, thereby modulating light by changing a liquid crystal alignment direction on the pixel electrode. As shown in FIG. 10A, when no voltage is applied, each of the liquid crystal droplets 104 is oriented in an irregular direction. In this state, the polymer 105
A difference in refractive index occurs between the liquid crystal and the liquid crystal 104, and the incident light is scattered. Here, as shown in FIG.
When a voltage is applied to 3, the directions of the liquid crystals are aligned. If the refractive index when the liquid crystal is oriented in a certain direction is adjusted in advance to the refractive index of the polymer, incident light is emitted from the array substrate 101 without being scattered. In addition, when the liquid crystal is expressed in the form of water droplets as in PDLC, the average of the diameters of the liquid crystal in the form of water droplets is referred to as the average particle diameter. It is called the average pore size of the network.

In order to realize high-quality image display using a polymer-dispersed liquid crystal, the amount of light transmitted in a scattered state (hereinafter referred to as “scattered state”)
The amount of scattered light) and the amount of light transmitted in the transmitted state (hereinafter
It is necessary to increase the ratio (hereinafter referred to as contrast) of the transmitted light amount. If the contrast is low, the gradation display characteristics deteriorate. When constructing a liquid crystal projection television, a contrast of 100 or more is required. Since the polymer-dispersed liquid crystal does not require the use of a polarizing plate, the light use efficiency is 80 to
There is also about 85%. Therefore, in order to increase the contrast, the amount of scattered light may be reduced. In order to reduce the amount of scattered light, the thickness of the liquid crystal may be increased. However, when the thickness of the liquid crystal is increased, the voltage for bringing the liquid crystal into a transmission state increases, and the liquid crystal cannot be driven. Therefore, in the present invention, the light absorbing film is formed on the surface of the liquid crystal panel which is in contact with the liquid crystal. Alternatively, a light absorbing wall is formed in the liquid crystal panel layer. When the liquid crystal layer is scattered, a part of the scattered light is absorbed by the light absorbing film or the light absorbing wall. Therefore, the contrast is improved.

A liquid crystal projection television according to the present invention is configured using the liquid crystal panel according to the present invention. It has a light source such as a metal halide lamp or a xenon lamp, an optical system such as a lens for guiding light emitted from the light source to the liquid crystal panel, and a lens system for projecting light modulated by the liquid crystal panel. To obtain a color display image, R
It is configured using three liquid crystal panels that modulate light, G light and B light.

[0022]

When no voltage is applied to the liquid crystal layer, light incident on the liquid crystal layer is scattered by the liquid crystal layer. When the scattering characteristics of the liquid crystal become close to the perfect diffusion state, the incident light is irregularly reflected on the glass substrate surface, the counter electrode, and the like. When the irregularly reflected light is absorbed by the light absorbing film formed on the surface in contact with the liquid crystal, the amount of light emitted from the liquid crystal panel decreases. When a voltage is applied to the liquid crystal layer and the liquid crystal layer is in a transmission state, incident light is emitted as it is. Therefore, the contrast is improved.

In order to absorb only the light scattered between the liquid crystal layers, a light absorbing film is formed on the BM. If there is no BM, the light absorbing film absorbs the light incident on the liquid crystal panel as it is and enters a heated state. By forming the BM, it is possible to prevent the incident light from directly irradiating the absorbing film.

[0024] By using the polymer-dispersed liquid crystal as the liquid crystal, a polarizing plate is not required, more than three times higher brightness display of the liquid crystal panel using a TN liquid crystal is obtained. The liquid crystal panel of the present invention uses a polymer-dispersed liquid crystal, and obtains high scattering performance by optimizing the material, configuration and the like. Also, since no alignment film is required,
The manufacturing process of the liquid crystal panel is also simplified.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. Each drawing is modeled, and the physical film thickness or shape does not always match. Parts unnecessary for the description are omitted.

FIG. 1 is a sectional view of the liquid crystal panel of the present invention. On the array substrate 12, a TFT 15 as a switching element, a pixel electrode 14, and the like are formed. On the other hand, the counter electrode 1 made of ITO is
3 are formed. A BM is formed on the counter electrode 13. The conventional BM is to prevent the TFT from being irradiated with light, or to prevent the liquid crystal on the signal line from performing an alignment operation irrelevant to image display, and to prevent the alignment operation from appearing as a display (hereinafter, referred to as image noise). Was.
BM17 of the present invention is to incident light in addition to direct the light absorbing layer 18 so as not irradiated. As a material for forming the BM, a metal material such as Al or Cr is selected. The light reflectance of the metal thin film is 60% or more for Cr and 8 for Al.
0% or more. The light absorbing film 18 is, for example, a material in which carbon is contained in an organic material such as an acrylic resin, or a material in which black beads or the like are dispersed in a similar organic material. FIG. 2 is a plan view of the BM. As shown in FIG. 2 (a), the source signal line (a), the gate signal line (c) and the TFT (a) may be formed at all positions. It may be formed only in part. It is needless to say that the BM 17 need not be formed when the incident light is relatively weak or when the heat resistance of the liquid crystal panel is high.

When the polymer dispersed liquid crystal 16 scatters, the light incident on the liquid crystal layer is scattered. The scattering performance is maximized in the fully diffused state. The incident light repeats irregular reflection in the liquid crystal. Part of the light enters the light absorbing film 18 and is absorbed. The rate of absorption is substantially proportional to the formation area of the light absorbing film 18. Therefore, the larger the formation area of the light absorbing film 18, the lower the amount of emitted light at the time of scattering. When a voltage is applied to the polymer-dispersed liquid crystal 16, the incident light is emitted as it is in the transmission state. Light is absorbed at the time of scattering and is the same as at the time of transmission, so that the contrast is improved.

The liquid crystal material used in the liquid crystal panel of the present invention is preferably a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal, and may be a single or two or more liquid crystal compounds or a mixture containing a substance other than the liquid crystal compound. Good. Incidentally, the nematic liquid crystal of relatively large cyanobiphenyl difference extraordinary refractive index n _e and ordinary index n _o of the liquid crystal materials mentioned above are most preferred. As the polymer matrix material, a transparent polymer is preferable. As the polymer, any of a thermoplastic resin, a thermosetting resin, and a photocurable resin may be used. In view of the above, it is preferable to use an ultraviolet curing type resin. As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or acrylic oligomer which is polymerized and cured by irradiation with ultraviolet light 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.

Further, a polymerization initiator may be used in order to carry out the polymerization promptly.
Methyl-1-phenylpropan-1-one (“Darocur 1173” manufactured by Merck), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-
ON ("Darocure 1116" manufactured by Merck Ltd.), 1-bidroxycyclohexylphenylketone ("Irgacure 184" manufactured by Ciba-Gaiky), benzyl methyl ketal ("Irgacure 651" manufactured by Ciba-Geigy) and the like are listed. In addition, a chain transfer agent, a photosensitizer, a dye, a cross-linking agent and the like can be appropriately used as optional components.

The proportion of the liquid crystal material in the polymer-dispersed liquid crystal layer is not specified here, but is generally about 20 to 90% by weight, preferably about 50 to 80% by weight. If it is less than 20% by weight, the amount of liquid crystal droplets is small,
Poor scattering effect. On the other hand , if it exceeds 90% by weight , the polymer and the liquid crystal tend to phase-separate into two upper and lower layers, the proportion of the interface becomes small, and the scattering characteristics deteriorate. The structure of the polymer-dispersed liquid crystal layer varies depending on the liquid crystal fraction, and is approximately 50% by weight.
If it is less than 50%, the liquid crystal droplets are present as independent droplets, and if it is 50% by weight or more, a continuous layer is formed in which the polymer and the liquid crystal are intertwined. The thickness of the liquid crystal 16 is preferably in the range of 5 to 25 μm, and more preferably in the range of 8 to 15 μm. If the film thickness is small, scattering characteristics are poor and contrast cannot be obtained. Conversely, if the film thickness is large, high voltage driving must be performed, and it becomes difficult to design a drive IC for driving pixels. The average particle diameter of the water-drop liquid crystal of the polymer-dispersed liquid crystal or the average pore diameter of the polymer network is preferably 0.5 μm or more and 3.0 μm or less.

Similarly, as shown in FIG.
The same effect can be obtained by forming a light absorbing wall 42 between the substrate and the array substrate 12 . The formation position is preferably on the source signal line 41 or the like. The light-absorbing wall 42 may be formed of the same material as the light-absorbing film 18 and / or a resin vehicle containing cyanine black, which is a phthalocyanine-based pigment having high electrical insulation. In addition,
Needless to say, the above materials can be used for the light absorbing film. At this time, if the insulation rate of the light absorbing wall is low, the liquid crystal 1
This results in lowering the retention of the six layers. Therefore, an insulating film is formed on the counter electrode 13 with SiO ₂ or the like,
A light absorbing wall may be formed on the insulating film. Further, it is not necessary to completely contact the counter electrode 13. For example, even if the height of the light absorbing wall is の of the thickness of the liquid crystal 16 layer, the effect of absorbing light can be obtained. In order to prevent the light absorbing wall from being directly irradiated with incident light, the BM may be formed of a metal thin film on the upper surface of the light absorbing wall.

FIG. 3 is a sectional view of a liquid crystal panel according to a second embodiment of the present invention. The liquid crystal panel is of a reflection type. The thickness of the glass substrate 11 is 0.8 to 1.1 m
m. Antireflection film 3 on one side of glass substrate
1 is formed. The antireflection film 31 is formed by laminating three or two thin films. In the case of three layers, it is used to prevent reflection in a wide visible light range, and is called a multi-coat. In the case of two layers, it is used to prevent reflection in a specific visible light range, and this is called a V coat. Liquid crystal panel shown in (Fig. 3)
When a liquid crystal projection television is constructed by using a liquid crystal, a multi coat is applied to modulate white light, and a V coat corresponding to each wavelength is applied to modulate light of specific wavelengths of R, G, and B lights. . As a matter of course, the V coat has a greater effect of reducing the reflectance for light of a specific wavelength.

In the case of multi-coating, the optical film thickness of aluminum oxide (Al ₂ O ₃ ) is nd = λ / 4, zirconium oxide (ZrO ₂ ) is nd = λ / 2, and magnesium fluoride (MgF ₂ ) is nd. = Λ / 4. Normally, a thin film is formed with λ set to 550 nm or a value near 550 nm. In the case of V coating, silicon monoxide (SiO) is optically film thickness nd = λ / 4 and magnesium fluoride (MgF ₂ ) is nd = λ / 4, or yttrium oxide (Y ₂ O ₃ ) and magnesium fluoride (Mg
F ₂ ) is formed by stacking nd = λ / 4. Note that SiO
Since there is an absorption band on the blue side, it is preferable to use Y ₂ O ₃ when modulating blue light. In addition, Y ₂ O ₃ is more preferable from the viewpoint of stability of the substance. In this case, λ
Is the peak wavelength of the light to be modulated, that is, the center wavelength. Hereinafter, unless otherwise specified, λ is a peak wavelength or a central wavelength of incident light. In addition,
n is the refractive index of the thin film, and d is the physical thickness.

On the other surface of the glass substrate 11, a counter electrode and an antireflection film are formed. Precisely, a thin film is formed before and after the ITO film serving as the counter electrode, and the antireflection film 32 is formed. 32b is an ITO film to be a counter electrode. The thickness of the ITO film is set so that the optical thickness is λ / 2. If λ is 550 nm, d = 1375 °. The ITO film is formed corresponding to λ. 32
a and 32c denote the refractive index of the glass substrate 11 and the ITO film 3;
This is a thin film made of a material having a refractive index between 2b and 2b. It is preferable that the thin films 32a and 32c are formed of the same substance and have the same thickness. The optical thickness of the thin film is nd =
λ / 4. The change in the thickness of the ITO film 32b significantly affects the change in the reflectance at the peak wavelength.
The change in the film thickness of 2c does not affect much.

The materials of the thin films 32a and 32c are aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y
₂ O ₃ ), silicon monoxide (SiO), magnesium oxide (MgO), tungsten oxide (WO ₃ ), cerium fluoride (CeF ₃ ), and lead fluoride (PbF ₂ ). Among them, Al ₂ O ₃ , Y ₂ O ₃ , and CeF ₃ are preferable in terms of stability, light transmittance, and film uniformity.

Assuming that λ is 550 nm, the thin films 32a, 3a
When Al ₂ O ₃ (n ≒ 1.63) is used for 2c, the physical film thickness formed is in the range of d = 700Å-1000Å
The physical thickness of the film (n ≒ 2.0) 32b is 1150Å to 1
The range may be 600 °. Thin film 32c is ITO film 3
The voltage applied to 2b will drop,
If it is 0 ° or less, there is almost no effect. Conversely, the effect of increasing the retention of the liquid crystal layer is obtained. If the ITO film is formed at a temperature of at least 1000 ° by vapor deposition or sputtering at a temperature of at least 200 °, a necessary and sufficient resistance value and transparency can be obtained. In the case of Y ₂ O ₃ (n ≒ 1.78), 650Å
It may be 900 °.

By forming the antireflection films 31 and 32 as described above, the light reflectance can be greatly reduced. When the band of the light to be modulated is relatively narrow, the reflectance is 0.1% or less at the peak wavelength. Can be realized. It is apparent that the anti-reflection film 31 does not need to be formed when optical coupling with another component is taken. What is important in the present invention is that the ITO film 32b as a counter electrode is used to prevent reflection.
That is, the stop film 32 is formed. Naturally IT
The O film 32b is configured or formed so that a common electrode potential or the like can be applied. Instead of using the ITO film 32b, a transparent conductive film such as indium oxide or tin oxide may be used. In such a case, the thin films 32a and 32c may be formed with an optical film thickness that reduces the reflectance by the optical interference effect. Alternatively, the ITO film should be understood to include the above-mentioned film material.

A reflective electrode 34 is formed on the TFT 15 with an insulating film 33 interposed. Reflective electrode 34 and TFT 15
Is electrically connected to the connection terminal 35. Insulating film 3
Material 3 is an organic material of polyimide or SiO
₂ , inorganic materials such as SiNx are used. Reflective electrode 3
No. 4 has a surface formed of an Al thin film. Although it may be formed by using Cr or the like, the reflectance is lower than that of Al, and the reflection electrode is easily broken due to being hard.

The connection terminal 35 has a depression of 0.5 to 1 μm. However, the polymer dispersed liquid crystal 16 does not need to be subjected to a treatment such as alignment, and does not pose a problem. The aperture ratio is 80% or more when the pixel size is 100 μm square, and 70% when the pixel size is 50 μm square. However, on the TFT and the like, the reflection electrode 34 has irregularities, and the reflection efficiency is somewhat reduced.

Source signal lines and gate signal lines are not shown, but are formed on the array substrate . The signal
Since the structure that covers substantially the reflective electrode 34 is formed on the line and TFT 15, image noise is not generated by the liquid crystal alignment operation on the signal lines and TFT.

The light absorbing film 18 is formed on the upper electrode 32 between the reflective electrodes 34. The effect of light absorption and the like are the same as those described above. The light absorbing film 18 can be used instead of the BM,
There is also an effect that a break between pixels can be sharpened.

In the embodiment, Al ₂ O ₃ is used as the antireflection films 31 and 32 and the thin film of the pixel electrode shown in FIG. 4. However, the present invention is not limited to this. May be performed as long as the substance has a refractive index of between. For example, when Y ₂ O ₃ is used, the reflectance can be reduced in a wider wavelength band than Al ₂ O ₃ . Also, S
In the case of iO (n = 1.70), the reflectance can be extremely low in a wide visible light wavelength band. However, S
Since iO easily changes to SiO ₂ , the substance has poor stability. In the case where SiO is used, the above problem is eliminated if a protective thin film is formed between the SiO film and the liquid crystal 16 . As the protective film, a substance close to the refractive index nx exhibited by the liquid crystal 16 at the time of scattering may be used. The refractive index of the polymer-dispersed liquid crystal during scattering is 1.
Since it is 60 to 1.63, for example, Al ₂ O ₃ (n =
1.63) may be used. By forming a protective thin film,
The SiO thin film is no longer linked to oxygen atoms, and can be kept in a materially extremely stable state.

The thickness of each thin film is approximately λ / 2 or approximately λ / 4, and λ is the peak wavelength. However, the present invention is not limited to this. For example, if the refractive index of a glass substrate is 1.5
2, the refractive indices n _x of the liquid crystal and 1.60, S glass substrate
When iO is laminated at λ / 4, ITO at λ / 2, and SiO at λ / 4, if the peak wavelength λ is 500 nm, 500 nm
Is slightly more than 0.05%. However, the reflectance becomes the lowest at around 400 nm or 600 nm, and the reflectance at that time is about 0.02%. This indicates that the reflectance is lowest at a wavelength lower than the position set at the peak wavelength λ. In general, in the case of a three-layer coating, it is normal to exhibit a W characteristic in which the reflectance is reduced at two places. Therefore, when it is necessary to obtain an extremely low reflectance, it is apparent that it is better to use a portion having a reflectance lower than the peak wavelength λ. In this case, it may be considered that the peak wavelength is temporarily set to 500 nm for the purpose of producing an antireflection film for 600 nm or 400 nm. That is, the peak wavelength may be regarded as a value for achieving the target reflectance, and is not limited to the average value or the peak wavelength of the wavelength of the incident light.

The use of a thin film having a refractive index of 1.60 or more and 1.80 or less has a large effect of reducing the reflectance. Further, by setting the ratio to be 1.65 or more and 1.75 or less, the reflectance reduction effect in a wide wavelength band, particularly
When a material having a refractive index of about 1.70 such as O is used,
IT in a wide wavelength band from about 400 nm to 700 nm
The reflectance of light generated between the thin film and the O thin film (n = 2.0) can be reduced to 0.1% or less.

Although the thin film 1 and the thin film 2 are formed of one kind of substance, the refractive index of the thin film is 1.60 or more.
The number is not particularly limited as long as it is 80 or less.
For example, there is a method of forming a thin film with an equivalent film. The equivalent film is usually a thin film obtained by laminating two or more kinds of very thin thin films and equivalently obtaining a target refractive index. As an example, the thin film 1 is made of Al ₂ O ₃ (n ≒ 1.63), ZrO ₂ (n ≒ 2.0
5), three layers of Al2O3 (n ≒ 1.63) may be formed. Therefore, the thin film 1 and the thin film 2 should not be defined by the film quality and the material, but should be considered to have a film thickness satisfying a desired refractive index equivalently.

Further, although the thin film 1 and the thin film 2 formed before and after the ITO film are formed of the same material in the embodiment, the present invention is not limited to this. For example, in FIG. 3, the thin film 32 a is approximately λ / 4 of SiO (n = 1.7), the ITO film 32 b is approximately λ / 2, and the thin film 32 c is Y on the glass substrate 11 .
Approximately λ / 4 may be laminated with ₂ O ₃ (n = 1.78).
In the above configuration, the SiO is not exposed on the substrate surface and the thin film 32a is not exposed.
The stability of both the thin film 32c and the thin film 32c is improved as compared with the structure of SiO. In addition, the reflectance can be 0.1% or less in the visible light range.

Hereinafter, a liquid crystal projection television according to the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram of the liquid crystal projection television of the present invention. However, components unnecessary for the description are omitted. In FIG. 5, reference numeral 51 denotes a condensing optical system in which a concave mirror and a xenon lamp which is a good point light source are used as light generating means. If the power consumption is from 250 W to 1 KW, a practically sufficient screen luminance can be obtained. The concave mirror is configured to reflect only visible light. Reference numeral 52 denotes a UVIR cut mirror that transmits infrared light and ultraviolet light and reflects only visible light. 53a is BDM,
53b is GDM and 53c is RDM. In addition, BDM
The arrangement of the RDMs 53a to 53c is not limited to the above-described order, and it goes without saying that the last RDM 53c may be replaced with a total reflection mirror.

Reference numerals 54a, 54b and 54c are liquid crystal panels of the present invention. 55a, 55b, 55c, 57a, 57
b and 57c are lenses, and 56a, 56b and 56c are
Aperture as squeezing. In order to obtain a sufficient contrast, the projection optical system is constituted by 55, 56 and 57. It is clear that the aperture is not necessary when the F-number of the lens 55 or the like is large, and it is also clear that the projection lens system can be replaced with one lens. The F-number of the projection lens type needs to be 8.0 or more.

The projection lens system has a function of transmitting parallel rays transmitted through each liquid crystal panel and blocking light scattered by each liquid crystal panel. As a result, a high-contrast full-color display can be realized on the screen. Aperture 56
The contrast is improved by reducing the aperture diameter of a or increasing the F-number of the projection lens. However, the image brightness on the screen decreases.

The operation of the liquid crystal projection television according to the present invention will be described below. Since the respective modulation systems of R, G, and B light have almost the same operation, the modulation system of B light will be described as an example. First, white light is emitted from the condensing optical system 51, and the B light component of the white light is
reflected by a. The B light is incident on the polymer dispersed liquid crystal panel 54a. The polymer dispersed liquid crystal panel (FIG. 1)
As shown in FIGS. 0 (a) and (b)), the scattering and transmission state of the incident light are controlled by the signal applied to the pixel electrode, and the light is modulated.

The scattered light is shielded by the aperture 56a. Conversely, light within a predetermined angle passes through the aperture 56a. The modulated light is enlarged and projected on a screen (not shown) by the projection lens 57a. As described above, the B light component of the image is displayed on the screen. Similarly, the polymer dispersed liquid crystal panel 54b modulates the light of the G light component, and the polymer dispersed liquid crystal panel 54c modulates the light of the R light component, so that a color image is displayed on the screen.

FIG. 6 is a configuration diagram of a liquid crystal projection television corresponding to the reflection type liquid crystal panel of FIG. 61 is a liquid crystal panel of the present invention. As the light emitting source 66, a metal halide lamp, a xenon lamp, or the like is applicable. The shorter the arc length of the lamp, the higher the contrast of the displayed image. When an arc length of 5 mm is used for a metal halide lamp, F5 depends on the F-number of the projection lens.
6 In contrast will be close to 100. Xenon run
If a lamp having an arc length of about 1 mm is used, a contrast of 200 or more can be realized. But Xeno
Lamps have half the light conversion efficiency of metal halide lamps.
There is only 1/3. In the liquid crystal projection television of the present invention, 25
A 0 W metal halide lamp was used. Light emitted from the light emitting source 66 is condensed by the lens 65 and is incident on the mirror 64. Center of lens 62 and center of panel and mirror 6
A line connecting one end of 4 is an optical axis 67. The lens 62 is configured or arranged to focus on the liquid crystal layer of the liquid crystal panel 61 and on one end of the mirror 64. Lens 62
Is focused on the liquid crystal layer to realize telecentricity.

The light that has entered the mirror 64 enters the lens 62 and enters the liquid crystal panel 61. The liquid crystal panel 61 modulates the incident light according to the applied video signal, and a part of the modulated light enters the lens 62 again. The pixel where the liquid crystal is completely transmitted passes through the hole between the stopper 63 and the mirror 64 , and the light incident on the pixel in the scattering state is blocked. The light passes through the hole according to the degree of modulation and is projected on the intermediate pixel. Although the projection may be performed as it is, a projection lens is usually arranged at the emission end of the stopper 63. When the incident light is white light, the liquid crystal panel 61 is provided with a multi-coat antireflection film on the surface of the counter electrode substrate. To display a color image, a mosaic color filter may be attached to the liquid crystal panel. The light from the light emitting source 66 may be separated into three wavelength bands of R, G, and B light by a color separation optical system using a dichroic mirror or the like, and a liquid crystal panel that modulates each light may be provided. In that case, a V coat type antireflection film corresponding to the peak wavelength of each light is applied to the surface of each liquid crystal panel.

When the light modulated by each liquid crystal panel is superimposed on a screen and projected using a color combining optical system or three projection lenses, a color image is displayed. Note that the polymer-dispersed liquid crystal panel has poor scattering characteristics for R light. Therefore, in the liquid crystal projection television of the present invention, the liquid crystal panel for modulating the R light has a larger liquid crystal film thickness than other liquid crystal panels and / or has a larger average particle diameter of the liquid crystal in the form of water droplets. In the case of PNLC, the average pore size of the polymer network is increased.

The liquid crystal projection television of the present invention is not limited to the rear liquid crystal projection television, but may be a front liquid crystal projection television for projecting an image on a reflection screen. Furthermore, in the liquid crystal projection type television of this embodiment, the color separation is performed by the dichroic mirror, but the present invention is not limited to this. For example, the color separation may be performed by using an absorption color filter.

In the liquid crystal projection type television of the embodiment shown in FIG. 5, one projection lens system is provided for each of the R, G and B light modulation systems, but the invention is not limited to this. It is needless to say that, for example, the display image modulated by the liquid crystal panel using a mirror or the like may be combined into one and then incident on one projection lens system and projected. Further, the present invention is not limited to providing three liquid crystal panels for modulating R, G, and B lights. For example, a television that attaches a mosaic color filter to one liquid crystal panel and projects an image of the panel may be used.

Although the light absorbing film or the light absorbing wall is formed on the liquid crystal panel, the present invention is not limited to this. It is obvious that both the light absorbing film and the light absorbing wall may be formed. .

[0060]

As described above, according to the present invention, by forming a light absorbing film and / or a light absorbing wall on a liquid crystal layer, light that is diffusely reflected by the liquid crystal layer during scattering can be absorbed. Therefore, the contrast of the liquid crystal panel can be improved.

Further, the use of the polymer-dispersed liquid crystal eliminates the need for a polarizing plate, and is 3 times smaller than that of a TN liquid crystal panel.
Higher-brightness display more than twice can be realized. This means not only that the light use efficiency can be improved, but also that the conversion of light into heat can be greatly reduced, and that the performance of the panel does not deteriorate due to heating. This is very effective when the intensity of light incident on one liquid crystal panel is as high as tens of thousands of lux, such as in a liquid crystal projection television.

Since the liquid crystal projection type television of the present invention employs a liquid crystal panel of a polymer dispersed liquid crystal, a high-luminance display can be realized and a large screen of 200 inches or more can be handled. Further, the liquid crystal panel for R light modulation increases the thickness of the liquid crystal and / or increases the flat particle size of the water-droplet liquid crystal, so that an image display with good white balance and contrast can be realized.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal panel according to an embodiment of the present invention.

FIG. 2 is a plan view of a counter electrode substrate according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a liquid crystal panel according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a liquid crystal panel according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a liquid crystal projection television according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of a liquid crystal projection television according to another embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of a liquid crystal panel.

FIG. 8 is a partial cross-sectional view of a conventional liquid crystal panel.

FIG. 9 is a configuration diagram of a conventional liquid crystal projection television.

FIG. 10 is an explanatory diagram of an operation of a polymer dispersed liquid crystal.

[Explanation of symbols]

 Reference Signs List 11 counter electrode substrate 12 array substrate 13 counter electrode 14 pixel electrode 15 TFT 16 polymer dispersed liquid crystal 17, 88 black matrix 18 light absorbing film 31, 32 anti-reflection film 34 reflecting electrode 42 light absorbing wall 63 stopper 64 mirror 86 TN liquid crystal 87a , 87b Alignment film 104 Water-like liquid crystal 105 Polymer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-251222 (JP, A) JP-A-3-2825 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/13 G02F 1/1333 G02F 1/1335 G02B 1/10

Claims (10)

(57) [Claims] 1. Formed or arranged in a matrix
A first electrode substrate having a pixel electrode, a second electrode substrate on which a counter electrode and at least one thin film are laminated, and a liquid crystal sandwiched between the first electrode substrate and the second electrode substrate Polymerizes and cures liquid resin components containing
Comprising: a formed light modulation layer, a light absorbing layer or a light-absorbing wall effective light to the image display is formed in the region other than the region that passes in the optical modulation layer by
And the refractive index of the thin film is the refractive index of the second electrode substrate
A liquid crystal panel characterized by being between the refractive index of the counter electrode . 2. A first electrode substrate having a first electrode, a second electrode substrate having a second electrode, and sandwiched between the first electrode substrate and the second electrode substrate. A polymer-dispersed liquid crystal layer, and a light-absorbing film or a light-absorbing wall formed in the polymer-dispersed liquid crystal layer other than a region through which light effective for image display passes. The proportion of the material is not less than 20% by weight and not more than 90% by weight, and the average particle diameter of the liquid crystal droplets or the average pore diameter of the polymer network is 0.5 μm.
Not less than 3.0 μm and the thickness of the liquid crystal layer is 5 μm.
A liquid crystal panel having a thickness of not less than 25 μm or less. 3. A first electrode substrate, a second electrode substrate having a transparent electrode and a black matrix, containing liquid crystal sandwiched between the first electrode substrate and the second electrode substrate Polymerize and cure liquid resin components
A light modulation layer formed by, comprising a light absorbing layer, the light absorbing film is a on the black matrix and the
A liquid crystal panel formed on a surface in contact with a light modulation layer . 4. A first electrode substrate having pixel electrodes formed or arranged in a matrix, a second electrode substrate having a counter electrode formed thereon, the first electrode substrate and the second electrode substrate Polymerizes and cures the liquid resin component containing liquid crystal sandwiched between
A liquid crystal panel, characterized in that a light modulation layer formed, equipped with light-absorbing wall formed between the pixel electrode and a black matrix formed on the upper surface of the light absorption wall by. 5. A first electrode substrate having pixel electrodes formed or arranged in a matrix, and a second electrode on which a first thin film, a third thin film, and a second thin film are formed.
Polymerizing and curing a liquid resin component containing a liquid crystal sandwiched between the first electrode substrate and the second electrode substrate .
Comprising a light modulation layer formed by said third film is a conductive transparent electrode, the refractive index of the second thin film and the first film is a refractive index of the second electrode substrate And a refractive index of the third thin film. 6. A first electrode substrate having pixel electrodes formed or arranged in a matrix, and a second electrode on which a first thin film, a third thin film, and a second thin film are formed.
Polymerizing and curing a liquid resin component containing a liquid crystal sandwiched between the first electrode substrate and the second electrode substrate .
A light modulating layer formed by the method, a peripheral portion of the pixel electrode, and the second portion facing the peripheral portion.
A light absorbing film or a light absorbing wall formed or formed on at least one of the electrode substrates, wherein the third thin film is a conductive transparent electrode, the first thin film and the second thin film Wherein the refractive index is between the refractive index of the second electrode substrate and the refractive index of the third thin film. 7. An optical film thickness of the first thin film and the second thin film is approximately λ / 4 (λ is a peak wavelength or a center wavelength of light incident on the second electrode substrate), and the third thin film Has an optical thickness of approximately λ / 2, wherein the first thin film and the second thin film are aluminum oxide,
7. The liquid crystal panel according to claim 5, wherein the liquid crystal panel is one of yttrium oxide and silicon monoxide. 8. The liquid crystal panel according to claim 1, wherein: a light generating unit; an optical unit for guiding light generated by the light generating unit to the liquid crystal panel; And a projecting means for projecting the reflected light. 9. A reflective polymer-dispersed liquid crystal panel, light-generating means, a mirror for reflecting light generated by the light-generating means toward the polymer-dispersed liquid-crystal panel, and A liquid crystal projection television, comprising: a projection unit that projects modulated light; and a stopper that blocks light scattered by the polymer dispersed liquid crystal panel. 10. A first polymer-dispersed liquid crystal panel that modulates red light, a second polymer-dispersed liquid crystal panel that modulates green light, and a third polymer-dispersed liquid crystal panel that modulates blue light. The average particle size of the liquid crystal droplets or the average pore size of the polymer network of the first polymer dispersed liquid crystal panel is larger than the average particle size of the liquid crystal droplets of the other polymer dispersed liquid crystal panel or the average pore size of the polymer network. 10. The liquid crystal projection television according to claim 9, wherein