JP3048468B2 - LCD projection TV - 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.

[0002]

2. Description of the Related Art A liquid crystal display device is useful because it has many features such as light weight and thinness, and research and development thereof have been active. However, there are many problems such as difficulty in increasing the screen. Therefore, in recent years, a liquid crystal projection television which obtains a large display screen by enlarging and projecting a display image of a small liquid crystal panel by a projection lens or the like 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.

First, a conventional liquid crystal projection television will be described with reference to the drawings. FIG. 12 is a configuration diagram of a conventional liquid crystal projection television. In FIG. 12, 121 is a condensing optical system, 122 is an infrared cut mirror for transmitting infrared light, 12
3a is a blue light reflecting dichroic mirror (hereinafter referred to as BDM), 123b is a green light reflecting dichroic mirror (hereinafter referred to as GDM), 123c is a red light reflecting dichroic mirror (hereinafter referred to as RDM), 124a, 124b, 124c , 12
6a, 126b and 126c are polarizing plates, 125a, 125b and 125c are transmission type conventional TN liquid crystal panels, and 127a, 127b and 127c are projection lens systems. Note that components unnecessary for the description, such as a field lens, are omitted from the drawings.

The relationship and operation of each component of a conventional liquid crystal projection television comprising the above components will be described below with reference to FIG. First, blue light (hereinafter, referred to as B light) of white light from the light condensing optical system 121 is reflected by the BDM 123a, and this B light is incident on the polarizing plate 124a. BDM12
The light transmitted through 3a is reflected by the GDM 123b as green light (hereinafter referred to as G light), and is reflected by the polarizing plate 124b and the RDM 123c.
Red light (hereinafter referred to as R light) is reflected by the polarizing plate
It is incident on 124c. Each of the polarizing plates 124a, 124b, and 124c transmits only one of the longitudinal wave component or the transverse wave component of each color light, and irradiates each liquid crystal panel with the polarization direction of the light aligned. At this time, 50% or more of the light is reflected by the polarizing plates 124a, 124b, 12
It is absorbed by 4c, and the brightness of the transmitted light is at most half or less.

Each liquid crystal panel modulates the transmitted light according to a video signal. The modulated light passes through each of the polarizing plates 126a, 126b, and 126c according to the degree of modulation, and the light passes through each of the projection lens systems 127a and 127a.
The light enters the lenses 7b and 127c and is enlarged and projected on a screen (not shown) by the lens system. Next, a general liquid crystal panel will be described. FIG. 13 is a plan view of the liquid crystal panel. In FIG. 13, each component will be described.
Reference numeral 31 denotes a glass substrate (hereinafter, referred to as an array substrate) on which a thin film transistor (hereinafter, referred to as a TFT) as a switching element is formed, and 132, a substrate on which a transparent electrode made of ITO or the like is formed (hereinafter, referred to as an opposite substrate) ), 1
36 is a TF connected to a gate signal line on the array substrate 131.
Drive IC for applying a signal for controlling ON / OFF of T
(Hereinafter referred to as a gate drive IC) 135 is a drive IC (hereinafter referred to as a source drive IC) for applying a data signal to a source signal line on the array substrate 131.
33 is a polarizing film, and 134 is a sealing resin for sealing the liquid crystal. In the following, the components denoted by the same reference numerals have the same content, the same configuration, or an approximate configuration. Fig. 14
(A) is a plan view of one pixel portion of a conventional liquid crystal panel.
FIG. 14B is a cross-sectional view taken along line DD ′ of FIG. However, in the drawings, unnecessary portions are omitted for ease of explanation, and the drawings are modeled. The above applies to the following drawings.

In FIGS. 14A and 14B, reference numeral 42 denotes a source signal line, one end of which is connected to a source drive IC 135. Reference numeral 41 denotes a gate signal line, one end of which is connected to the gate drive IC 136. Reference numeral 26 denotes an array substrate on which a first electrode, that is, a pixel electrode 44 made of ITO is formed. In FIG. 15, 21 is a counter substrate, 151 is T
N liquid crystal layer (hereinafter referred to as TN liquid crystal layer),
Its thickness is around 5 μm. A light-shielding layer (black matrix) 27 is formed on the counter electrode 22, and an alignment film (not shown) made of an organic material such as a polyimide resin is formed on the counter electrode 22 and the pixel electrode 24. . Note that the size of one pixel is about 500 μm to 30 μm.

FIG. 16 is a diagram for explaining the operation of a TN liquid crystal panel, which is a conventional liquid crystal panel. In FIG. 16, 161 is a polarizing plate, 162 is a polarization direction, 163 is a transparent electrode, 164 is a liquid crystal molecule, 165 is a signal source, and 166 is a switch. As shown in FIG. 16, the incident light rotates 90 degrees in the off state and transmits without rotating in the on state. Therefore, the two polarizing plates 161
If the polarization directions are orthogonal, light is transmitted in the off state,
In the on state, light is shielded. However, the opposite is true if the polarization directions are parallel to each other. As described above, the TN liquid crystal panel modulates light to display an image.

[0008]

As apparent from the above description, in a liquid crystal panel using a TN liquid crystal, it is necessary to make linearly polarized light incident on the liquid crystal panel. Therefore, it is necessary to arrange polarizing plates before and after the liquid crystal panel. The polarizer described above theoretically absorbs more than 50% of the light. Therefore, as a conventional problem, when a TN liquid crystal panel is used as a light valve and enlarged projection is performed on a screen, only a low-luminance screen can be obtained. Since a liquid crystal panel using a polymer-dispersed liquid crystal does not use a polarizing plate, the light use efficiency can be extremely increased. Similarly, a liquid crystal panel using a diffraction phenomenon does not require a polarizing plate, so that the light use efficiency can be increased.

Hereinafter, the polymer-dispersed liquid crystal will be briefly described. Polymer-dispersed liquid crystals are 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 called a PNLC, and 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.

The PD liquid crystal panel 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, the PN liquid crystal panel uses the irregularity of the alignment of liquid crystal molecules. Irregular orientation state,
When 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 the PD liquid crystal panel and the PN liquid crystal panel is based on a model. Although the present technology is not limited to one of the PD liquid crystal panel and the PN liquid crystal panel, the PD liquid crystal panel will be described as an example for ease of description.
The PD liquid crystal panel and the PN liquid crystal panel are collectively referred to as a polymer dispersed liquid crystal panel. Further, liquids containing liquid crystal to be injected into the polymer dispersed liquid crystal panel are collectively referred to as liquid crystal solution or resin, and a state in which the resin component in the liquid crystal solution is polymerized and cured is referred to as polymer.

As the polymer matrix in the polymer dispersed liquid crystal layer to be the liquid crystal layer of such a dispersion type liquid crystal display element, basically, any thermoplastic resin or thermosetting resin may be used as long as it is transparent. However, ultraviolet curable resins are the most convenient, have good performance, and are commonly used. The reason is that the conventional method of manufacturing a TN mode liquid crystal panel can be applied as it is. As a conventional method of manufacturing a liquid crystal panel, first, a predetermined electrode pattern is formed on two upper and lower substrates in advance, and the two substrates are overlapped so that the electrodes face each other. At this time, a spacer having a predetermined size and a uniform particle size is sandwiched between the substrates, and the two substrates are fixed with an epoxy resin sealing material in a state where a gap between the two substrates can be maintained. Next, a manufacturing method of injecting a liquid crystal into the empty cell thus obtained is often used.

In order to manufacture a dispersion type liquid crystal panel by applying this manufacturing method, if the material of the polymer matrix is an ultraviolet-curable resin, particularly an acrylic resin as an example, the monomer can be used before the injection. And / or exists as a relatively low viscosity precursor such as an oligomer, and the blend with the liquid crystal has sufficient fluidity to be injected at room temperature. If a method of forming a polymer-dispersed liquid crystal layer by irradiating light after injection and promoting a curing reaction is used, a dispersion-type liquid crystal panel can be easily formed.

Further, by irradiating the panel with ultraviolet rays after the injection, only the resin causes a polymerization reaction to become a polymer, and only the liquid crystal is phase-separated. Liquid crystal droplets are formed,
On the other hand, when the amount of the liquid crystal is large, the polymer matrix exists in the liquid crystal material in the form of particles or a network, and the liquid crystal is formed so as to form a continuous layer. At this time, the particle size of the liquid crystal droplet,
Alternatively, unless the pore diameter of the polymer network is uniform to some extent and the size is in the range of 0.1 μm to several μm, the light scattering property is poor and the contrast does not increase.
For this purpose, the material must be a material that can be cured in a relatively short time, and an ultraviolet curable resin is desirable.

FIG. 17 shows the operation of the polymer dispersed liquid crystal panel.
A brief description will be given using (a) and (b). FIG. 17 (a) (b)
FIG. 4 is an explanatory diagram of the operation of the polymer dispersed liquid crystal panel. Fig. 17
17A and 17B, reference numeral 171 denotes an array substrate, 172 denotes a pixel electrode, 173 denotes a counter electrode, 174 denotes a liquid crystal in the form of droplets, 175 denotes a polymer, and 176 denotes a counter substrate. The pixel electrode 172 has a TFT
And the like, and a voltage is applied to the pixel electrode by turning on and off the TFT, and the direction of liquid crystal alignment on the pixel electrode is changed to modulate light. As shown in FIG. 17 (a), when no voltage is applied, each liquid crystal 174 is oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer 175 and the liquid crystal, and the incident light is scattered. Here Figure 17
As shown in (b), when a voltage is applied to the pixel electrode, 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 171 without being scattered.

As described above, since the polymer-dispersed liquid crystal panel does not use a polarizing plate, the light use efficiency is high and a display image with extremely high luminance can be obtained. However, there are the following problems when trying to use the liquid crystal for a liquid crystal panel.

In order to put this polymer dispersed liquid crystal panel into practical use as a device, it is required that it can be driven at a low voltage and that it has a sufficient contrast ratio.
In order to obtain particularly good display, the contrast ratio is preferably 30: 1 or more for direct viewing and 100: 1 or more for projection. In order to increase the contrast ratio, it is necessary to enhance the light scattering characteristics. One possible target for the scattering effect is complete diffusion. When the converging angle σ (half angle) is used, the contrast ratio CR in perfect diffusion is CR = 1 /
It can be calculated by sin ² σ. For example, S.I.D. Bulletin Vol. 18 (1977) pp. 134-146 (Projection
Systems for Light Valves, Proceeding of the
S, I, D, 18/2 Second Quarter, 1977, P.E. 134
~ P. 146). Increasing the thickness of the polymer-dispersed liquid crystal layer improves the light scattering performance, but increases the driving voltage, and causes a problem that TFT driving becomes difficult.

In particular, when used as a projection type display, a concave mirror condensing optical system using a metal halide lamp, which is widely used at present, and a projection optical system that matches the concave mirror condensing optical system.
The number is 4 to 5, and even if a polymer-dispersed liquid crystal panel showing a completely diffused state is used, the contrast ratio is insufficient at about 65: 1 according to the above formula.

A projection is formed on at least one of the array substrate and the opposing substrate of the liquid crystal panel on a surface facing the liquid crystal layer, and the projection is used as a diffraction grating, and the refractive index of the liquid crystal layer is controlled by an electric field. When the difference in refractive index between the layer and the protrusion disappears, the diffraction effect is eliminated, and a method of displaying the image by controlling the diffraction effect so that the diffraction effect appears according to the difference in the refractive index has been proposed (Japanese Patent Publication No. 53-53). No. 3928). However, in the case of a nematic liquid crystal used for a TN liquid crystal, it is difficult to control the alignment on a substrate on which a projection having a height of several μm and a pitch of several μm is formed.

When a TN liquid crystal is used as a light valve, more than 50% of the light is absorbed by a polarizing plate, so that there is a problem that the light utilization is low and a high-luminance display cannot be performed.
Therefore, an object of the present invention is to provide a high-brightness display and high-contrast liquid crystal projection television using a polymer-dispersed liquid crystal panel which does not require the use of a polarizing plate as a light valve.

[0021]

According to a first aspect of the present invention, there is provided:
Liquid crystal projection television has light generating means and diffraction grating
Or diffraction by applied voltage using the diffraction phenomenon
A liquid crystal panel that modulates the intensity of light to modulate light generated by the light generating means; a first optical element component that guides light generated by the light generating means to the liquid crystal panel; and a liquid crystal panel modulated by the liquid crystal panel. and and a second optical element component for projecting the light, first optical element component is characterized by having an anamorphic lens. The liquid crystal according to claim 2 of the present invention.
The projection television may have light generating means and a diffraction grating.
Or the diffracted light is
Modulating the intensity to modulate the light generated by the light generating means.
A liquid crystal panel, and the light generated by the light generating means.
Optical component leading to a crystal panel, and the liquid crystal panel
A second optical element part for projecting light modulated by
However, the aperture ratio of the second optical element component differs depending on the direction.
It is characterized by having a deformed aperture. Claim 3 of the present invention
The liquid crystal projection television described in claim 1 or 2
The liquid crystal panel must be a polymer dispersed liquid crystal panel
It is characterized by. A liquid crystal projection type television according to claim 4 of the present invention.
The light generation means according to claim 1 or 2,
Generated light is blue light, green light and red light by color filter
Is divided into three wavelengths of light, and the liquid crystal panel
At least one of the three predetermined ranges of wavelengths.
Liquid crystal panels arranged for each wavelength of light.
Anamo used as the first optical component for guiding light to the tunnel
At least one or more curvatures of the Fick lens
And a curvature different from that of the anamorphic lens . A liquid crystal projection television according to claim 5 of the present invention
The light generating means according to claim 1 or 2,
Light is blue light, green light and red light by a color filter.
And the liquid crystal panel is
For at least one of the three predetermined ranges of wavelengths
Liquid crystal panel arranged for each wavelength of light
Used as a second optical element part for projecting modulated light
Of the apertures of at least one of the irregular apertures
It is characterized in that the aperture ratio of the irregular stop is made different .

[0022]

The liquid crystal projection television of the present invention uses a polymer dispersed liquid crystal panel or a diffraction type liquid crystal panel as a light valve. In the case of a polymer dispersed liquid crystal panel, black display is performed when the panel is in a scattering state. For this reason, unnecessary scattered light is shielded using a stop. However, if the aperture of the aperture is reduced, the white display will be darker if white display is performed in the transmission state. Therefore, by using an anamorphic lens having a different curvature depending on the direction as the first optical element component for guiding the light generated by the light generating means to the liquid crystal panel, the light converging angle of the light source is changed to perform bright white display. Can be. In addition, as a second optical element component for projecting light modulated by the liquid crystal panel, it corresponds to an anamorphic lens,
By using a modified stop having a different aperture ratio depending on the direction, the light utilization rate is further increased.

In the case of the diffraction type liquid crystal panel, incident light is diffracted in a liquid crystal off state by a projection formed in the liquid crystal panel, and light traveling straight is reduced. However, when a stripe-shaped protrusion is formed, light is diffracted in one direction, but is not diffracted at all in a direction perpendicular thereto. Therefore, the brightness and the image quality of the projected image become non-uniform. This can be solved by using an anamorphic lens having a different curvature depending on the direction as the first optical element component for guiding the light generated by the light generating means to the liquid crystal panel. Further, the utilization rate of light is increased. The same effect can be obtained by using a modified stop having a different aperture ratio depending on the direction as the second optical element component that projects the light modulated by the liquid crystal panel.

Diffraction scale when combined with polymer dispersed liquid crystal
The operation of the child will be described. Polymer refractive index n_pSame as
Form a protrusion with a light-transmitting material with a refractive index at or near one
To achieve. Refractive index n of light transmitting material_tAnd In addition, liquid crystal
Ordinary refractive index n_o, The extraordinary light refractive index is n_eAnd n_p= N
_oAnd When the liquid is in the off state as shown in FIG.
Refractive index n of the crystal layer as a whole_xIs a macroscopic polymer
Refractive index n_p, The refractive index n of the liquid crystal_oAnd n_eRefraction
Indicates the rate. However, if the liquid crystal is aligned,
The apparent refractive index is (n_o+ N_e) / 2 and the refractive index is large
It becomes possible to take it. Refractive index n of protrusion_t
And n_xAre different from each other, a difference in refractive index occurs between the two. liquid crystal
Light incident on the panel is diffracted by the protrusion and goes straight
Less components. In other words, this projection is a diffraction grating
(Hereinafter, protrusions are referred to as diffraction gratings). this
This means that the scattering state is apparently higher. Figure
As shown in FIG. 17 (b), the liquid crystal molecules are constant when in the on state.
In the direction of n_p= N _o= N_xBecomes Accordingly
And n_p= N_t= N_xBecomes This is the refraction of the liquid crystal layer.
Rate n_xAnd the refractive index n of the diffraction grating_tThe difference in the refractive index of
Means Therefore, no diffraction grating is formed
The incident light goes straight as it is
You. Refractive index of liquid crystal layer and polymer and liquid crystal layer and diffraction grating
The larger the difference, the greater the scattering and diffraction efficiency
Become.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a liquid crystal projection television according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view conceptually showing the principle configuration of the liquid crystal projection television of the present invention. An active matrix type polymer dispersed liquid crystal panel (hereinafter, referred to as a liquid crystal panel) 11 is used as a light valve, and an anamorphic lens 13 is arranged between the light source 12 and the liquid crystal panel 11. The light from the light source 12 is made incident on the liquid crystal panel 11 by the anamorphic lens 13 while changing the converging angles in the horizontal and vertical directions. The concave mirror 18 is provided for condensing the light from the light source 12 and increasing the light utilization factor, and the absence of the concave mirror does not impair the gist of the present invention. The image formed on the liquid crystal panel 11 is projected on a screen 17 via a projection lens 16. Light is scattered by the liquid crystal panel 11 according to the projection image, and the scattered light is
And does not reach the screen 17.

FIG. 2 is a sectional view of the liquid crystal panel 11 used as a light valve in this embodiment. At least one is transparent on the array substrate 26 and the opposing substrate 21
A pixel electrode 24 and a counter electrode 22 are formed by transparent electrodes such as O, respectively. 25 is a thin film transistor (TFT) as a switching element, and 27 is a black matrix. The configuration of the array substrate 26 is substantially the same as the configuration of the conventional example shown in FIG. A polymer dispersed liquid crystal layer 23 is sandwiched between the two substrates. The thickness of the polymer-dispersed liquid crystal layer 23 is preferably in the range of 5 μm to 25 μm, and 8 μm
It is preferably in the range of ~ 15 m. This means that when the film thickness exceeds 20 μm, a high voltage is required for driving, while the film thickness is 8 μm.
If it is less than m, the scattering characteristics deteriorate and the contrast decreases.

The liquid crystal material used for the liquid crystal panel is preferably a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal, and may be a mixture containing one or more liquid crystal compounds or a substance other than the liquid crystal compound.
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, and the polymer may be any of a thermoplastic resin, a thermosetting resin, and a photocurable resin. 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 quickly carry out the polymerization. For example, 2-hydroxy-2-methyl-1-
Phenylpropan-1-one ("Darocur" manufactured by Merck & Co., Ltd.)
1173 "), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (" Darocur 1116 ", manufactured by Merck), 1-vidroxycyclohexylphenyl ketone (" Irgacure 184 ", manufactured by Ciba-Geigy)
)), Benzyl methyl ketal (“Irgacure 651” manufactured by Ciba Geigy) and the like.

In addition, a chain transfer agent, a photosensitizer, a dye, a crosslinking agent, and the like can be appropriately used as optional components.
A liquid or viscous material obtained by uniformly dissolving a liquid crystal material in the ultraviolet curable compound is injected between two substrates, and then irradiated with ultraviolet light to cure only the ultraviolet curable compound. Only the material undergoes phase separation to form a polymer dispersed liquid crystal layer.

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 70% by weight. 20
If it is less than 10% by weight, the amount of liquid crystal droplets is small and the scattering effect is poor. When the content is 90% by weight or more, the polymer and the liquid crystal tend to be phase-separated into upper and lower layers, the ratio of the interface is reduced, and the light scattering is reduced. The structure of the polymer-dispersed liquid crystal layer changes depending on the liquid crystal fraction. At about 50% by weight or less, the liquid crystal droplets exist as independent droplets, and at 50% by weight or more, a continuous phase is formed in which the polymer and the liquid crystal are intertwined with each other. . FIG. 3 is a schematic plan view of the modified stop 14 used in this embodiment. 31 is an opening. When the light emitted from the light source 12 is incident on the liquid crystal panel 11 by the anamorphic lens 13, the condensing angle in the horizontal direction is represented by F =
10. The converging angle in the vertical direction is F = 5, and the aperture of the modified stop 14 is formed in a shape corresponding to this light beam. Its shape is generally elliptical.

As the light source 12, a halogen lamp, a metal halide lamp, a xenon lamp, or the like is used, and a parallel light beam having a short arc length is desirable. In this embodiment, the concave mirror 18 is arranged to increase the light collecting efficiency, but other means such as a condenser lens may be used.

Hereinafter, a second embodiment of the liquid crystal projection type television according to the present invention will be described, but the description will be limited only to the difference from the first embodiment. Therefore, items not explained are the first
This is the same as the embodiment. The same applies to the following other embodiments. FIG. 4A is a plan view of one pixel of a liquid crystal panel used as a light valve in the second embodiment of the present invention. However, in order to make the drawing easy to see, the counter electrode substrate and the like are omitted from FIG. In FIGS. 4A and 5B and FIGS. 5A and 5B,
41 is a gate signal line, 42 is a source signal line and 51 is TE
Black matrix shielding T, 45 is array substrate 26
The projections (hereinafter referred to as diffraction gratings) formed thereon.
As described above, the drawings are modeled. For example, the number, width, shape, and the like of diffraction gratings correspond to this. That is, the present invention is not limited to the number, width, and the like. Specifically, the pixel size is 200 to 30 μm, and the pitch P of the diffraction grating is 30 to 2 μm. Therefore, the number of diffraction gratings is usually larger than that shown in FIG. 4 (b) is a sectional view at ^A-A, line of FIG. 4 (a). FIG.
4A is a cross-sectional view when the counter substrate 21 is mounted on the array substrate 26 of FIG. 4A and a nematic liquid crystal 53 is injected between the substrates. FIG. 5B is a perspective view schematically showing a state where the liquid crystal 53 is oriented. Examples of the material of the diffraction grating include SiOx, SiNx, TaOx, inorganic substances such as glass-based substances, and organic substances such as polyimide and acrylic resin. The selection of the material is determined according to the refractive index of the liquid crystal. The refractive index of each material is the ordinary light refractive index n of the liquid crystal.
_o is 1.45 to 1.55, the liquid crystal of the extraordinary refractive index n _e from 1.65 to 1.80
Is often used. By rubbing the space between the projections 45, the liquid crystal molecules 53 are aligned as shown in the perspective view of FIG.

The dielectric constant of the diffraction grating is preferably larger than the dielectric constant in the direction perpendicular to the orientation vector of the liquid crystal used and smaller than the dielectric constant in the direction parallel to the liquid crystal. Preferably, the dielectric constant in the direction parallel to the orientation vector of the liquid crystal used is made to match.
By doing so, a sufficient electric field can be applied to the liquid crystal layer above the diffraction grating, and the direction of the electric field is also perpendicular to the substrate.

From the above examination, it is considered that SiO _2, which is easy to form and process in terms of process, is suitable as the current inorganic material as the material for forming the diffraction grating. The refractive index of SiO ₂ is usually about 1.45 to 1.50. Further, as a forming method, a pattern mask may be formed and etched after depositing SiO ₂ . As the organic material, it is optimal to use an ultraviolet curable resin. As a method for forming a diffraction grating using such a material, a diffraction grating may be applied on a substrate using a roll quarter or a spinner, and only a necessary portion may be polymerized using a pattern mask. There is also a method in which a photosensitive resin composed of a polymer and a dopant is spin-coated on a substrate, exposed through a pattern mask, and then subjected to dry development by a method of sublimating a dopant by heating under reduced pressure.

The pitch p and height d of the diffraction grating 45 vary considerably depending on the wavelength λ of the light to be modulated, the refractive index of the liquid crystal layer 53, the directivity of light of the optical system, the required diffraction efficiency, and the like.
When no voltage is applied, the emitted light beam is affected by scattering and diffraction. For example, as shown in FIG. 1, when the diffraction grating 45 has a rectangular cross-sectional shape, the diffraction angle θ and the efficiency η ₀ of the _0th- order diffracted light are given as follows.

Sin θ = mλ / p (where m is the order of diffraction) η ₀ = 0.5 * (1 + cos δ) where δ = 2πΔnd / λ Therefore, the pitch p and height d are the directivity of light of the optical system,
It should be determined by the diffraction angle θ and the wavelength λ. But,
It often depends on the process conditions for forming the diffraction grating. The pitch t is about 2 μm to 60 μm, and most preferably, 4 μm to 20 μm. Although the shape of the diffraction grating is often sinusoidal or trapezoidal due to the process, there is no problem in its effect if it is designed according to the desired diffraction efficiency and diffraction angle. This is the same for the other embodiments described below.

In the diffraction type liquid crystal panel used as a light valve in the second embodiment of the present invention, the shape of the diffraction grating 45 is a stripe shape, and the light incident on the panel is diffracted in only one direction. FIG. 6 schematically shows the intensity of the emitted light beam.

When a liquid crystal projection device is constructed by using such a liquid crystal panel as a light valve, in order to keep a large contrast ratio and to make it bright, a modified stop 14 is used.
May be made small in the diffraction direction and large in the direction in which no diffraction occurs. For example, it is preferable to use an aperture 14 having a shape as shown in the schematic plan view of FIG. In FIG. 7, reference numeral 71 denotes an opening. Further, by using the anamorphic lens 13, if the condensing angle on the light source side is changed depending on the direction in accordance with the opening of the diaphragm 14, the effect is further enhanced.

Consider a case where a liquid crystal having a positive dielectric anisotropy is used. Refractive indices n _x of the liquid crystal layer 53 when the off state is indicated by _{(n o + n e) /} 2. Conversely, when the switch is in the ON state, it becomes n _o . Thus, the liquid crystal is allowed to appear the diffraction grating when the off state, to extinguish the diffraction grating when the ON state, the refractive index n _t = n _o of the diffraction grating 45 or, if such a value in the vicinity thereof Good. That is, the refractive indices n _x of the liquid crystal layer when the liquid crystal is off (n _o + n _e) /
Because it is 2, n _t ≠ n _x a is the diffraction grating 45 and the liquid crystal layer 53
Refractive index difference _{Δn = (n e -n o)} / 2 occurs. Since the liquid crystal on the contrary the refractive index of the liquid crystal layer when on becomes n _o, n
the _o = n _t. That is, there is no difference in refractive index between the diffraction grating 45 and the liquid crystal layer 53.

Hereinafter, a third embodiment of the present invention will be described. FIG. 8 is a sectional view of a liquid crystal panel used as a light valve in the present invention. As in the liquid crystal panel used in the second embodiment, a diffraction grating 85 is formed on the array substrate 26. However, the polymer-dispersed liquid crystal 83 is used as the liquid crystal material as in the first embodiment of the present invention. Consider a case where a liquid crystal having a positive dielectric anisotropy is used. Refractive indices n _x of the liquid crystal layer 83 when the off state is indicated generally at _{(2n o + n e) /} 3. Conversely, when the switch is in the ON state, it becomes n _o . Thus, the liquid crystal is allowed to appear the diffraction grating when the off state, to extinguish the diffraction grating when the ON state, the refractive index n _t = n _o of the diffraction grating 85 or may be such that the value in the vicinity thereof . In other words, since when the liquid crystal OFF state the refractive indices n _x of the liquid crystal layer is a _{(2n o + n e) /} 3, n t ≠ n x
In and difference in refractive index diffraction grating 85 and the liquid crystal layer 83 Δn = (n _e -
n _o ) / 3. Since the liquid crystal on the contrary the refractive index of the liquid crystal layer when in the ON state becomes n _o, When n _o = n _p n _o
= A n _t. That is, there is no difference in refractive index between the diffraction grating 85 and the liquid crystal layer 83.

It is desirable that the difference between the refractive index n _{t of the} diffraction grating and the refractive index n _p of the polymer be within 0.1.
Furthermore, materials within 0.1 should be selected. Hereinafter, a fourth embodiment of the present invention will be described. FIG. 9 (a)
(B) shows a plan view and a cross-sectional view of one pixel of the liquid crystal panel of this embodiment. On the pixel electrode 44, protrusions 95 are formed at regular intervals in a block shape or a column shape. In the second or third embodiment, since the protrusions were formed in a stripe shape, the incident light was diffracted only one-dimensionally. If the projection is formed as in this embodiment, the incident light is diffracted two-dimensionally. As in the second or third embodiment, the liquid crystal layer uses a nematic liquid crystal, preferably a polymer-dispersed liquid crystal that does not require alignment control.

When a liquid crystal projection television is constructed using such a liquid crystal panel as a light valve, the opening of the irregular stop 14 is small in the diffraction direction and does not diffract in order to keep the contrast ratio large and bright. The direction should be small. Further, by using the anamorphic lens 13, if the condensing angle on the light source side is changed depending on the direction in accordance with the opening of the diaphragm 14, the effect is further enhanced.

Hereinafter, a liquid crystal projection television according to an embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a configuration diagram of a liquid crystal projection television according to one embodiment of the present invention. However,
Components unnecessary for the description are omitted. In FIG.
A condensing optical system 101 has a concave mirror and a 250 W metal halide lamp as light generating means inside.
The concave mirror is configured to reflect only visible light. Further, an ultraviolet cut filter is arranged at the emission end of the light collecting optical system 101. An infrared cut mirror 102 transmits infrared light and reflects only visible light. However, it is needless to say that the infrared cut mirror 102 may be arranged inside the condensing optical system 101. 103a is B
DM and 103b are GDM and 103c is RDM. In addition, BD
The arrangement of M103a to RDM103c is not limited to the above order, and it goes without saying that the last RDM103c may be replaced by a total reflection mirror.

Reference numerals 104a, 104b and 104c are liquid crystal panels. This is because the scattering characteristic decreases as the light becomes longer in wavelength. 105a, 105b, 105c are anamorphic lenses,
106a, 106b and 106c, 107a, 107b and 107c are lenses, and 108a, 108b and 108c are deformed diaphragms. Note that 1
06, 107 and 108 constitute the projection lens system. R
Anamorphic lens 103c used for light modulation system
Has a larger radius of curvature. The aperture of the modified stop 108c used in the R light modulation system is smaller than the others. This is the liquid crystal panel 10 of the liquid crystal panel 104 that modulates the R light.
4c is because the scattering characteristics and the diffraction effect are lower than those of the liquid crystal panel 104a that modulates B light and the liquid crystal panel 104b that modulates G light.

Hereinafter, the operation of the liquid crystal projection television according to one embodiment of the present invention will be described. Since the respective modulation systems for red (R), green (G), and blue (B) light have almost the same operation, the modulation system for B light will be described as an example. First, white light is emitted from the condensing optical system 101,
The B light component of the white light is reflected by the BDM 103a.
This B light is incident on the liquid crystal panel 104a. The scattered or diffracted light is shielded by the aperture 108a, and conversely, parallel light or light within a predetermined angle passes through the aperture 108a. The modulated light is screened (not shown) by the projection lens 107a.
The projection is enlarged. As described above, the B light component of the image is uniformly displayed on the screen. LCD panel as well
104b modulates the light of the G light component, and the liquid crystal panel 104c modulates the light of the R light component, so that a color image is displayed on the screen.

The arrangement of the projection lens system is as follows. First, the distance L between the liquid crystal panel 104 and the lens 105
Is arranged so that the distance between the lens 105 and the aperture 108 is substantially equal. The above-described projection lens system plays a role of transmitting parallel rays transmitted through each liquid crystal panel and blocking light scattered or diffracted by each liquid crystal panel. As a result, a high-contrast full-color display can be realized on the screen. The contrast can be improved by reducing the aperture diameter D of the aperture 108. However, the image brightness on the screen decreases.

The thickness of the liquid crystal layer of the liquid crystal panel of this embodiment is
When it is 10 μm to 15 μm, the condensing angle θ of the lens needs to be 8 degrees or less in all angles. Above all, the optimal angle is around 6 degrees. At that time, the contrast is 100: 1 at the center of the screen, and when projected on a 40-inch screen with a rear television, the screen gain is 5 or more and 200 ft or more.
Compared with the projection type television, the same or higher screen brightness could be obtained. Use a short arc lamp. More specifically, the configuration diagram of FIG. 10 is shown as an example in a perspective view shown in FIG. In FIG. 11, 101 is a condensing optical system, 103 is a dichroic mirror, 104 is a liquid crystal panel, 111 is an anamorphic lens, 112 is a lens, 113 is a mirror, and 114a.
Reference numerals 114b and 114c denote projection lens systems provided with a modified stop 108.

The liquid crystal panel of the present invention has a TFT
The present invention is not limited to this, and is also effective for a liquid crystal display device using a two-terminal element such as a diode as a switching element.

Further, in FIG. 10 or FIG. 11, light is incident from the counter substrate side. However, the present invention is not limited to this, and it is apparent that the same effect can be obtained by incident from the array substrate. . As described above, the liquid crystal panel and the liquid crystal projection television of this embodiment are not affected by the incident direction of light.

In the embodiment of the liquid crystal projection television of the present invention, the rear liquid crystal projection television is described as an example. However, the invention is not limited to this, and the front liquid crystal projection television for projecting an image on a reflection screen is used. Needless to say, it can be a TV. Furthermore, in the liquid crystal projection television of this embodiment, the color separation is performed by the dichroic mirror. However, the present invention is not limited to this. For example, the color separation may be performed using an absorption color filter.

In the embodiments of the present invention, the liquid crystal panel is described as a transmissive liquid crystal panel. However, the present invention is not limited to this, and a reflective liquid crystal panel may be used. In that case, the pixel electrode may be a reflective electrode made of a metal material. The diffraction grating is formed on the counter electrode or the reflection electrode.

In the liquid crystal projection television of this embodiment, one projection lens system is provided for each of the R, G, and B light modulation systems. However, the present invention is not limited to this. It is needless to say that the display image modulated by the liquid crystal panel may be combined into one and then may be incident on one projection lens system and projected. Furthermore, although a liquid crystal panel for modulating each of the R, G, and B lights is provided, the invention is not limited to this. For example, a single-panel crystal projection television that attaches a mosaic color filter to one liquid crystal panel and projects the pixels of the panel may be used.

[0054]

As is apparent from the above description of the embodiment, the liquid crystal projection television of the present invention uses a liquid crystal panel which does not require the use of a polarizing plate, and is therefore at least twice as large as a TN liquid crystal panel. High brightness screen can be obtained. Further, when a diffraction grating is formed in the liquid crystal panel, when the liquid crystal is in the ON state, there is almost no difference in the refractive index from the liquid crystal layer, and the diffraction grating is not formed. Therefore, the light incident on the liquid crystal panel goes straight without being diffracted. Conversely, when the liquid crystal is in the off state, a difference in refractive index occurs between the liquid crystal layer and the diffraction grating, and the diffraction grating functions. Therefore,
Light incident on the liquid crystal panel is diffracted. This means that the amount of light traveling straight is reduced. The contrast of the image is greatly improved by the above-described diffraction effect.

Further, in the present invention, by using an anamorphic lens and a modified stop, an anamorphic lens is arranged before the light enters the panel, and the light is made to enter the panel after giving a difference in the spread angle of the light in advance. This corrects the omnidirectional scattering or diffraction performance. Alternatively, correction can be made by opening the aperture ratio of the aperture in a shape that differs depending on the direction in accordance with the difference in the scattering or diffraction characteristics of the panel. This makes it possible to obtain a uniform screen brightness and a uniform contrast ratio. In addition, a bright display can be obtained because the light use efficiency is improved. Furthermore, in the present invention, the contrast of the whole image is largely improved by changing at least one of the curvature of the anamorphic lens and the aperture diameter of the irregular stop mainly in the R light modulation system from other modulation systems. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a liquid crystal projection television according to the present invention.

FIG. 2 is a sectional view of a liquid crystal panel used as a light valve in the first embodiment of the liquid crystal projection television according to the present invention.

FIG. 3 is a schematic plan view of a modified stop of the liquid crystal projection television according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a liquid crystal panel used as a light valve in a liquid crystal projection television according to a second embodiment of the present invention.

FIG. 5 is a sectional view and a perspective view of a liquid crystal panel used as a light valve in a second embodiment of the liquid crystal projection television of the present invention.

FIG. 6 is a schematic diagram showing a distribution state of an emitted light intensity of a liquid crystal panel used as a light valve in a second embodiment of the liquid crystal projection television of the present invention.

FIG. 7 is a schematic plan view of a modified stop according to a second embodiment of the liquid crystal projection television of the present invention.

FIG. 8 is a sectional view of a liquid crystal panel used as a light valve in a liquid crystal projection television according to a third embodiment of the present invention.

FIG. 9 is a plan view and a sectional view of a liquid crystal panel used as a light valve in a liquid crystal projection television according to a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram of a first embodiment of a liquid crystal projection television according to the present invention.

FIG. 11 is a configuration diagram of another embodiment of the liquid crystal projection television of the present invention.

FIG. 12 is a configuration diagram of a conventional liquid crystal projection television.

FIG. 13 is a plan view of a conventional liquid crystal panel.

FIG. 14 is a plan view and a cross-sectional view of a conventional liquid crystal panel.

FIG. 15 is a cross-sectional view of a conventional liquid crystal panel.

FIG. 16 is an explanatory diagram of an operation of a TN liquid crystal panel.

FIG. 17 is a diagram illustrating the operation of a polymer dispersed liquid crystal panel.

[Explanation of symbols]

11 Light valve (liquid crystal panel) 12 Light source 13 Anamorphic lens 14 Irregular aperture 45 Projection (diffraction grating) 16 Projection lens 17 Screen 18 Concave mirror 21 Opposite substrate 22 Opposite electrode 23 Polymer dispersed liquid crystal layer 24 Pixel electrode 25 TFT 26 Array substrate 27 Black matrix 53 Nematic liquid crystal 101 Condensing optical system 102 Infrared cut mirror 103a, 103b, 103c, Dichroic mirror 104a, 104b, 104c Liquid crystal panel 106a, 106b, 106c, 107a, 107b, 107c Lens 108a, 108b, 108c Irregular aperture 105a, 105b, 105c anamorphic lens

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-102702 (JP, A) JP-A-63-147141 (JP, A) JP-A-3-87721 (JP, A) 122440 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/13 505 G02F 1/1335 G03B 21/00

Claims (5)

(57) [Claims] 1. A light generating means having a diffraction grating or being applied using a diffraction phenomenon.
A liquid crystal panel that modulates the intensity of the diffracted light with a voltage to modulate the light generated by the light generating means; a first optical element component that guides the light generated by the light generating means to the liquid crystal panel; A second optical element for projecting light modulated by a panel, wherein the first optical element has an anamorphic lens. 2. A light generating means having a diffraction grating or being applied by utilizing a diffraction phenomenon.
A liquid crystal panel that modulates the intensity of the diffracted light with a voltage to modulate the light generated by the light generating means; a first optical element component that guides the light generated by the light generating means to the liquid crystal panel; A second optical element part for projecting light modulated by a panel, wherein the second optical element part has a modified stop whose aperture ratio varies depending on the direction. 3. The liquid crystal panel is a polymer dispersed liquid crystal panel.
A liquid crystal projection television according to claim 1 . 4. The light generated by the light generating means is blue by a color filter.
Light of three predetermined wavelength ranges: colored light, green light and red light
And the liquid crystal panel has the three predetermined ranges of waves.
Light of each wavelength arranged for at least one of the long light
The first optical element that guides light to the liquid crystal panel
Of the anamorphic lenses used as
At least one piece of curvature is added to the curvature of another anamorphic lens.
The liquid crystal projection television according to claim 1 or 2, wherein the rate is different from the rate . 5. The light generated by the light generating means is separated by a color filter into light having wavelengths in three predetermined ranges of blue light, green light and red light, and the liquid crystal panel emits light having wavelengths in the three predetermined ranges. Light of each wavelength, arranged for at least one of
The modulated light on the LCD panel
Of the irregular stops used as second optical element parts
At least one or more aperture ratios differ from the aperture ratios of other irregular apertures.
The liquid crystal projection television according to claim 1 or 2, wherein