JP3313142B2 - Liquid crystal panel and projection display device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection for enlarging and projecting an image that is largely displayed on a small liquid crystal panel onto a screen
The present invention relates to a projection display device (hereinafter, referred to as a liquid crystal projection television) and 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. Currently, 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 is a flat color display '9.
1 P194-P205 Nikkei BP Publishing Co., Ltd. "

FIG. 8 is an equivalent circuit diagram of a liquid crystal panel. G _{1 to} G _m are gate signal lines, one end of which is connected to the gate drive IC 81. S ₁ to S _n is a source signal line, one end is connected to the source drive IC 82. Each pixel has a thin film transistor (hereinafter referred to as TFT) 83 for applying a signal to the pixel electrode, and an additional capacitor 84 for holding a signal is formed. Reference numeral 85 denotes a liquid crystal sandwiched between the pixel electrode and the counter electrode, which can be regarded as a capacitor in an electric circuit.

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. 9 is a sectional view of a conventional liquid crystal panel. The array substrate 92 and the counter electrode substrate 91 are held at an interval of 4 to 6 μm, and a twisted nematic liquid crystal (hereinafter, referred to as a TN liquid crystal) 96 is injected between the substrates. The periphery of the display area is sealed with a sealing resin (not shown). Reference numeral 98 denotes a black matrix formed of chromium or the like, 93 denotes a counter electrode formed of a transparent conductive material such as ITO, 95 denotes a pixel electrode, and 94 denotes a TFT.

Hereinafter, a conventional method for manufacturing a liquid crystal panel will be described. First, the array substrate 92 and the counter electrode substrate 91
Are coated with alignment films 97b and 97a, and are subjected to an alignment treatment by a rubbing process. After that, a sealing resin is applied to the periphery of the array substrate 92 except for the injection port of the TN liquid crystal. Further, beads for obtaining a uniform liquid crystal film thickness are sprayed on the counter electrode substrate 91. Next, the counter electrode substrate 91 and the array substrate 92 are bonded. Thereafter, the sealing resin is cured by irradiating or heating with ultraviolet rays. Next, the bonded substrate is placed in a vacuum chamber, and the gap between the array substrate 92 and the counter electrode substrate 91 is evacuated, and then the liquid crystal injection port is immersed in the liquid crystal. Then, when the vacuum in the vacuum chamber is broken,
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. 10 is a configuration diagram of a conventional liquid crystal projection television. (FIG. 10)
Reference numeral 1 denotes a condensing optical system; 102, a UVIR cut mirror that transmits infrared rays and ultraviolet rays; 103a, a blue light reflecting dichroic mirror (hereinafter, referred to as BDM); 103b, a green light reflecting dichroic mirror (hereinafter, referred to as GDM); Are red light reflecting dichroic mirrors (hereinafter referred to as RDMs), 104a, 104b, 104c,
106a, 106b, 106c are polarizing plates, 105a, 1
05b and 105c are transmissive TN liquid crystal panels, 107
Reference numerals a, 107b, and 107c denote 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 101 reflects blue light (hereinafter, referred to as B light) by the BDM 103a, and the B light enters the polarizing plate 104a. The light transmitted through the BDM 103a reflects green light (hereinafter referred to as G light) by the GDM 103b, and is reflected by the polarizing plate 104b.
The red light (hereinafter, referred to as R light) is reflected by c and is incident on the polarizing plate 104c. The polarizing plate 104 transmits only one of the longitudinal wave component and the transverse wave component of each color light, and irradiates each liquid crystal panel 105 with the polarization direction of the light aligned. At this time, 50% or more of the light is absorbed by the polarizing plate, and the brightness of the transmitted light is reduced to half or less at the maximum.

Each liquid crystal panel modulates the transmitted light according to a video signal. The modulated light passes through each of the polarizing plates 106a, 106b, and 106c according to the degree of modulation, enters each of the projection lens systems 107a, 107b, and 107c, and is 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 arranged on the outgoing light 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. Assuming that the pixel aperture ratio of the liquid crystal panel is 100% and the amount of light incident on the polarizer is 100%, the amount of light exiting the polarizer is 40%, the transmittance of the liquid crystal panel is 80%,
Since the transmittance of the analyzer is 80%, the overall transmittance is 0.4 × 0.8 × 0.8 = approximately 25%.
Can only be used effectively. Therefore, only a low-luminance image display can be realized with the TN liquid crystal panel.

The light lost by the polarizing plate or the like is turned into heat by the polarizing plate or the like. 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 for a liquid crystal projection television, the panel and the like are brought to a high temperature state, causing 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 leads to the formation of a large number of irregularities on the signal lines and the TFTs, which makes it impossible to perform a good rubbing process. Further, miniaturization of the pixel size increases the formation area of the TFT and the signal line occupying one pixel, and reduces the pixel aperture ratio. Diagonal 3 as an example
When 350,000 pixels are formed on an inch liquid crystal panel, the pixel aperture ratio is 30%. 10 when 1.5 million pixels are formed
Some estimates are just under%. These reductions in the pixel aperture ratio are not limited to lowering the brightness of the display image, but are also applied to portions other than the incident light apertures to be further heated, thereby accelerating the performance degradation described above.

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, causing a vicious cycle of heating.

As described above, the conventional TN liquid crystal panel can perform only low-luminance display, and the panel and the like are heated due to low light use efficiency. In particular, when a liquid crystal projection television was constructed using a TN liquid crystal panel, the performance of the liquid crystal panel and the like was significantly deteriorated.

[0015] The present invention has been made in view of the problems of the conventional liquid crystal panel and the projection shooting television, high brightness can be sufficiently corresponding to high vision display, providing high-quality liquid crystal panel and a liquid crystal projection TV Things.

[0016]

According to a first aspect of the present invention, there is provided a liquid crystal panel having at least one of a position on a switching element, a signal line, a counter electrode facing a switching element, and a counter electrode facing a signal line. And a dielectric film made of a material having a dielectric constant lower than that of the liquid crystal layer. By forming a dielectric film, image noise can be reduced. A liquid crystal panel according to a second aspect of the present invention includes a microlens substrate and a polymer-dispersed liquid crystal layer, and the proportion of the liquid crystal material in the polymer-dispersed liquid crystal layer is set to 50% by weight or more and 90 % by weight or less, The thickness of the liquid crystal layer is not less than 8 μm and not more than 15 μm. With this configuration, a high-contrast display can be realized.
The liquid crystal panel according to the third aspect of the present invention is a reflection type liquid crystal panel, and uses a polymer dispersed liquid crystal for a liquid crystal layer. Further, a microlens array is provided, and the microlens focal length b of the microlens array is b / b, where a is the average length of the horizontal length and the vertical length of the pixel.
The value of a is 3 or more and 8 or less. With this configuration, it is possible to realize a high brightness display and a high contrast display. A liquid crystal panel according to a fourth aspect of the present invention includes a microlens array, and a transparent material filled between the microlens array and the counter electrode substrate, and a surface or a counter electrode on the micro lens array and in contact with the transparent material. A light-shielding film is formed on the upper surface and in contact with the transparent material. With this configuration, it is possible to prevent a photoconductor phenomenon of a switching element such as a thin film transistor. Further, a projection display device of the present invention uses the liquid crystal panel according to the present invention as a light valve. With this configuration, high contrast and high brightness display can be realized.
You.

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.

[0018] PDLC utilizes the property that the refractive index differs 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. 11)
This will be briefly described using (a) and (b)). (FIG. 11 (a)
(B) is an explanatory view of the operation of the polymer dispersed liquid crystal panel. 11A and 11B, reference numeral 111 denotes an array substrate, 112 denotes a pixel electrode, 113 denotes a counter electrode, 114 denotes a liquid crystal in the form of droplets, 115 denotes a polymer, and 116 denotes a counter electrode substrate. A TFT (not shown) or the like is connected to the pixel electrode 112, and a voltage is applied to the pixel electrode by turning on and off the TFT, thereby modulating light by changing the liquid crystal alignment direction on the pixel electrode. As shown in FIG. 11A, when no voltage is applied, each of the liquid crystal droplets 114 is oriented in an irregular direction. In this state, the polymer 115
A difference in refractive index occurs between the liquid crystal and the liquid crystal 114, and the incident light is scattered. Here the pixel electrode 11 as shown in (FIG. 11 (b))
When a voltage is applied to 2 , 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, the incident light is emitted from the array substrate 111 without being scattered. Incidentally, when the liquid crystal as PDLC is represented water droplets form, referred to the average water droplet-shaped liquid crystal diameter and the average particle size, as when a network structure as PNLC, polymer network the average value of the pore size of the polymer network Is called the average pore size.

In order to realize high-quality image display using a polymer-dispersed liquid crystal, the amount of light transmitted in a scattering state (hereinafter, referred to as the amount of scattered light) and the amount of light transmitted in a transmitting state (hereinafter, referred to as a light amount). It is necessary to increase the ratio (hereinafter referred to as contrast) of the transmitted light amount. As the number of pixels of the liquid crystal panel increases, the aperture ratio of the pixels decreases. Therefore, a microlens is arranged on the light incident side of the liquid crystal panel so that the incident light can be favorably incident on the pixel opening. If the distance between the microlens and the liquid crystal layer is longer than the diameter of the microlens, the incident light will be applied to portions other than the pixel electrodes unless the directivity of the incident light is reduced. Therefore, in the liquid crystal panel of the present invention, the distance between the microlens and the liquid crystal layer is optimized to be 3 to 8 times the diameter of the microlens. The distance is achieved by using a resin and / or a thin glass substrate. The light-shielding film for the TFT is formed on a microlens substrate or the like. By forming the microlenses as described above and optimizing the distance between the microlenses and the liquid crystal, the amount of transmitted light increases and the contrast can be increased.

The liquid crystal projection television according to the present invention is constructed using the liquid crystal panel according to the present invention. The spread angle of the incident light is condensed within 3.5 degrees and made incident on the liquid crystal panel so that the light is effectively condensed by the microlens. However, the spread angle is a value at a half angle. On the emission side, an optical system that collects and projects light within 4.5 degrees and projects the light to effectively collect the light collected by the microlens is arranged. In order to satisfy the above conditions, a lamp having a short arc length is used as a light source.

[0023]

The polymer-dispersed liquid crystal panel does not use a polarizing plate for image display, and thus can display twice as high brightness as the TN liquid crystal panel.

When the number of pixels of the liquid crystal panel becomes large, the aperture ratio of the pixels decreases, and it is necessary to arrange a microlens at least on the incident light side in order to effectively use the light incident on the liquid crystal panel. However, if the directivity of the incident light is not narrow, the incident light will be applied to portions other than the pixel electrodes. Arc length 5 as a light source for liquid crystal projection television
When a metal halide lamp of mm is used, the divergence angle of light that can maximize and effectively use the light radiated by the lamp is about θ = 7 degrees. Note that the definition θ of the spread angle is as follows. (7) a light beam emitted from the light source as shown in the panel main ray 7 the incident surface of the
It is shown in a conical shape with 1 as the center. The angle θ between the light beam having the maximum angle and the principal ray among the light beams is defined as a spread angle. Is not defined only at the time of incidence, and may be an angle at which light is emitted from the panel and condensed by a lens or the like disposed downstream of the panel. In this specification, the angle of the incident light incident on the panel is called a spread angle. The angle emitted from the panel, incident on a projection lens or the like, and projected on a screen or the like is referred to as a capture angle. Seki the F-number of the general acceptance angle θ and the lens (hereinafter, referred to as F value)
It is well known that the relationship is expressed by the following equation:

Θ = sin ⁻¹ (1 / 2F) F is the F value of a normal projection lens or the like. That is, limiting the F value of the projection lens and the like is the same as limiting the take-in angle θ. For example, if the F-number of the projection lens is 4, incident light in the range of the take-in angle θ ≒ 4.2 can be projected. Conversely, the divergence angle can also be defined by the above equation. The spread angle θ of the light incident on the panel is 2.9.
If it is a degree, the F value of the light incident on the panel is about 10.
If a micro lens is attached to the incident surface of the panel, the incident light can be used effectively by setting the spread angle θ to be equal to or smaller than the take-in angle of the micro lens.

As described above, when a metal halide lamp having an arc length of 5 mm is used, the light use efficiency is highest when the divergence angle of light incident on the panel is around 7 degrees. To focus the light on the layer,
The distance from the microlens to the liquid crystal layer (hereinafter referred to as the focal length) must be at least three times and at most eight times the diameter of the microlens. Since the microlens array substrate is usually disposed on the counter electrode substrate of the liquid crystal panel, the thickness of the counter electrode substrate may be set to be the focal length. This means that if the pixel size becomes 100 μm or less, it is necessary to use a thin substrate as the counter electrode substrate. In a TN liquid crystal panel, it is necessary to apply an alignment film to a counter electrode substrate and perform a rubbing treatment. If the counter electrode substrate is thin, operability is poor and cannot be realized. However, a polymer-dispersed liquid crystal can be realized because the application of the alignment film and the rubbing treatment are unnecessary. Also, since the polymer dispersed liquid crystal is a solid unlike the TN liquid crystal, no distortion or the like occurs in the liquid crystal layer when a microlens substrate or the like is mounted on the counter electrode substrate.

The liquid crystal projection television of the present invention uses a xenon lamp having an arc length of about 1 mm as a light source.
With an arc length of 1 mm, the spread angle of light incident on the liquid crystal panel can be made within 3.5 degrees. Therefore, light with a narrow directivity can be made incident on the microlenses mounted on the liquid crystal panel, so that the incident light can be effectively used without irradiating the parts other than the pixel electrodes with the incident light. As the projection lens, a lens having a large F value can be used. In a polymer-dispersed liquid crystal, the smaller the take-in angle of the projection lens, the smaller the amount of scattered light and the more the contrast can be improved. That is, the divergence angle of the incident light is reduced, the light is condensed by the microlens and the incident light is used effectively, and the F value of the lens on the exit side is increased to improve the contrast.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal panel according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of the liquid crystal panel of the present invention. In FIG. 1, reference numeral 14 denotes a microlens, and one microlens is formed for each pixel. The microlens is preferably manufactured by an ion exchange method in which a part of the glass substrate is ion-exchanged to form a refractive index distribution. Less than,
The manufacturing method will be briefly described. Soda glass substrate 1
Ti is vapor-deposited on 1 and a hexagonal honeycomb-shaped circular window corresponding to the pixel is opened by photolithography. Next, it is immersed in a molten solution of a monovalent ion nitrate and subjected to a heat treatment at 400 ° C. or higher. At the time of heating, the cations that are being melted diffuse isotropically into the glass substrate 11 from the opening window to perform ion exchange. When ion-exchanged, the part produces a refractive index distribution. The refractive index is between 1.5 and 1.7. The microlens substrate 11 is manufactured as described above.

Reference numeral 12 denotes an array substrate. Array substrate 12
Above are a source signal line 18, a pixel electrode 19 and a TFT.
(Not shown) and the like are formed. The pixel aperture ratio is about 30% when 300,000 pixels are formed on a 3-inch size substrate. In the case of a liquid crystal panel compatible with high definition which is conventionally predicted, the number of pixels is required to be 1,000,000 or more, and the aperture ratio in that case is 10% or less. An opposing electrode 16 is formed on one surface of the opposing substrate 13, and the opposing substrate 1
The thickness of 3 is defined by the focal length of the micro lens 14. That is, the focal point of the micro lens 14 is
The thickness of the substrate 13 is defined so as to be connected at zero. Hereinafter, the opposite substrate 13 is also called a space substrate.

The thickness of the space substrate 13 needs to be three times or more and eight times or less the diameter of the microlens 14. When a metal halide lamp having an arc length of about 5 mm is used as a light source, the value is set to 3 times or more and 5 times or less . First
That the focus of the lens 14 is focused on the liquid crystal layer 20.
Was. That is, the focal length of the micro lens 14 is
It is necessary to make the diameter of the lens 14 three times or more and five times or less.
You. When a lamp having an arc length smaller than 5 mm is used, the length is set to 4 times or more and 8 times or less. When the pixel formation is rectangular, the microlens also has a horizontally long shape. In this case, the thickness of the space substrate is defined assuming that the average of the horizontal length and the vertical length of the pixel is used as the diameter of the microlens. That is, the focal length of the micro lens 14
Separation is a specified multiple of the average of the horizontal and vertical length of the pixel
Need to be

Reference numeral 15 denotes an adhesive layer for connecting the microlens substrate 11 and the space substrate 13, and more specifically, an adhesive mainly composed of an ultraviolet curable resin.

The material of the liquid crystal 20 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 is a mixture containing one or more liquid crystal compounds or substances other than the liquid crystal compounds. You may. 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 as the polymer, any of a thermoplastic resin, a thermosetting resin, and a photocurable resin may be used.
From the viewpoint of separation from the liquid crystal phase, it is preferable to use an ultraviolet-curable 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 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 20 is preferably in the range of 5 to 25 μm, more preferably 8 to 15 μm. If the film thickness is small, the scattering characteristics are poor and contrast cannot be obtained. Conversely, if the film thickness is large, high voltage driving must be performed, which makes it difficult to design a drive IC for driving pixels.

The polymer-dispersed liquid crystal does not require the formation of an alignment film. Therefore, it is only necessary to mount the substrate on which the counter electrode 16 made of ITO is formed on the array substrate. Therefore, even if the space substrate 13 is 1 mm or less, the panel can be sufficiently assembled. Further, since the polymer dispersed liquid crystal is a solid unlike the TN liquid crystal, it is resistant to pressure.
This means that the thickness of the liquid crystal 20 does not change due to the pressure applied when the microlenses 14 are bonded to the space substrate 13. In the TN liquid crystal panel, if the space substrate 13 is thin, a liquid crystal film thickness distribution occurs due to uneven thickness of the adhesive layer 15 or the like.

FIG. 2 is a sectional view of a liquid crystal panel according to a second embodiment of the present invention. A TFT in which a semiconductor layer is formed using amorphous silicon or the like is weak against light.
When light enters the TFT, a photoconductor phenomenon (hereinafter, referred to as a photoconductor) occurs, and the switching characteristics deteriorate. Therefore, in the TN liquid crystal panel, a light shielding film called a black matrix (hereinafter, referred to as BM) is formed on the counter electrode substrate. In the case of a polymer-dispersed liquid crystal panel, when a TFT using amorphous silicon is adopted, light must be shielded by some method so that light does not enter the semiconductor layer of the TFT. However, when the thickness of the space substrate 13 becomes 0.5 mm or less, B
It is quite difficult to form M. In the second embodiment, this problem is solved by forming a light-shielding film 21 on the substrate 11 with a microlens. A microlens substrate having a thickness of 1 to 1.4 mm is usually used. Therefore, BM
It is easy to pattern the light-shielding film 21 as a mask. When the thickness of the space substrate 13 is large, many portions which are shaded by the light shielding film 21 are generated.
Is small, or / and when the spread angle of the incident light is small, the shadowed portion is small. This is very advantageous when a liquid crystal panel having a pixel size of 100 μm or less and a lamp having a short arc length are used to constitute a liquid crystal projection television.

As a method for reducing light incident on the TFT, there is a method of forming a low dielectric constant film 31 on the TFT as shown in FIG. This low dielectric constant film 31 is a liquid crystal layer 20
Means a film made of a substance having a lower dielectric constant than the dielectric constant . The low dielectric constant film 31 prevents voltage from being applied to the liquid crystal layer on which the film is formed. If a voltage drop occurs in the low dielectric constant film, no voltage is applied to the liquid crystal layer, and the liquid crystal layer is constantly in a scattering state. If optics or the like is configured to display black in a scattering state in a liquid crystal projection television, the portion where the low dielectric constant film 31 is formed displays black. That is, the same effect as when the BM is formed by the TN liquid crystal panel can be obtained. The low dielectric constant film 31 is formed on the TFT 22 and the counter electrode 16 on the source / gate signal line. The T
The FT and the signal line are signals different from the normal image display,
The liquid crystal molecules of the liquid crystal layer are aligned. Therefore, image noise occurs. By forming the low dielectric constant film 31, the scattering state can be constantly achieved, and thus the image noise can be removed.

The low dielectric constant film 31 is desirably light transmissive. When irradiating ultraviolet rays to polymerize the liquid crystal solution,
If the low dielectric constant film 31 is a transparent material, ultraviolet light is transmitted,
This is because the liquid crystal solution under the low dielectric constant film 31 can also be polymerized. If it is BM, it will not be polymerized. An unpolymerized state results in a lack of material permeability of the liquid crystal layer 20, which causes deterioration of liquid crystal panel performance. The low dielectric constant film 31 is
It is clear that the effect can be obtained even if the TFT is formed directly on the TFT 22 or the signal line without forming the counter electrode 16 on the counter electrode 16 .
It is also clear that both may be formed. Thickness dielectric constant is small nearly as low dielectric constant film 31 as compared to the dielectric constant of the liquid crystal layer 20 may be thinner.

As a material for forming the low dielectric constant film 31,
As an inorganic material of S, it is easy to form and process in process.
_iO_TwoIs considered suitable. S_iO_TwoThe refractive index is usually
It is about 1.45 to 1.50, and its dielectric constant is
Low. The formation method is S _iO_TwoAfter vapor deposition,
A mask may be formed and etched. Further photopolymerizable
It is simpler to use an organic material. Organic materials
Is the same transparent polymer as that used for the liquid crystal layer 20.
It is best to use In addition, the registration of semiconductor circuits
Material can also be used. For example, a negative
The relative permittivity of the resist is 3 to 6, and the relative permittivity of the liquid crystal is 1
It can be regarded as a low dielectric constant substance which is smaller than 5 to 30. Up
The same organic material is used as the method for forming the low dielectric constant film 31.
On the substrate with a roll coater or spinner
Apply and polymerize only necessary parts using a pattern mask
And so on. In addition, it is
Spin-coated a photosensitive resin onto the substrate
After heating, the dopant is increased by heating under reduced pressure.
There is also a method of performing a dry phenomenon by a method of sintering.

FIG. 4 is a sectional view of a liquid crystal panel according to a fourth embodiment of the present invention. (FIG. 4) shows the counter electrode substrate
A light-shielding film 43 was formed on 13 . As described above, the light-shielding film 43 is shadowed by the incident light and causes a reduction in the pixel aperture ratio. The influence of the shadow becomes a problem when the pixel size is as large as 100 μm or / and the spread angle of the incident light is large. In the case described above, the configuration shown in FIG.
The light shielding film 43 is formed on the counter electrode substrate 13. Counter electrode
The space between the substrate 13 and the microlens substrate 11 is
A space is provided at a predetermined interval by the laser 42 , and the space is filled with a transparent resin material. It is to be noted that the predetermined interval is not limited to the beads but may be formed, for example, by forming a fiber or a bank.

As the transparent resin material, an ultraviolet curable type is preferable because it is easy to prepare a panel. Further, the difference in the refractive index between the transparent resin layer 41 and the beads 42 must be 0.1 or less. Since the light-shielding film 43 is preferably as close to the liquid crystal layer 20 as possible, the plate thickness of the counter electrode substrate 13 is preferably as thin as possible. However, the thickness of the resin layer 41 and the counter electrode base
It is the same as the first embodiment in that the thickness of the plate 13 plus the plate thickness is not less than 3 times and not more than 8 times the diameter of the microlens 14.

The arc length of the xenon lamp is about 1 mm. In the case of the arc length, the divergence angle of the incident light on the liquid crystal panel in which the light radiated from the lamp can be used most effectively is about 3.5 degrees to 2.5 degrees. This corresponds to an F value of 8 to 12. Therefore, the spread angle of the incident light needs to be within 3.5 degrees, and preferably within 3.0 degrees. The smaller the spread angle of the incident light is, the smaller the scattered light incident on the projection lens from the liquid crystal panel is. Therefore, the contrast is improved. However, when the width is too narrow, the amount of light incident on the liquid crystal panel also decreases, and conversely, the amount of transmitted light decreases and the contrast decreases. In the present embodiment, in view of the above, the spread angle of the incident light is set to 2.5 degrees.

[0046] Since the micro-lens refracts incident light, a lens on the output side, i.e. F value of the projection lens is required to be smaller than the F value of the incident side of the liquid crystal panel. If the size is too small, light that is scattered by the liquid crystal panel will also be collected, so that the contrast will be reduced. From the above, the take-in angle of the projection lens on the emission side needs to be within 4.5 degrees, and preferably within 4.0 degrees. In the present embodiment, taking the above into consideration, the take-in angle is set to 3.5 degrees. The liquid crystal panel has about 340,000 pixels, a pixel aperture ratio of 34%, and a panel size of about 2.
8 inches. In FIG. 5, reference numeral 51 denotes condensing optics.
System, 52 is a UVIR cut mirror, 53a, 53b, 5
3c is a dichroic mirror, 54a, 54b, 54c
Is a polymer dispersed liquid crystal panel, 55a, 55b, 55c, 5
7a, 57b, 57c lens, 56a, 56b and 56c are aperture as aperture. In addition, 5
5, 56 and 57 constitute a projection optical system. The set of 55, 56, and 57 is called a projection lens system unless there is a particular problem. The aperture is necessary for the description of the projection lens system, and is not actually used in many cases.

The projection lens system plays a role 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 can be improved by reducing the closed aperture of the lens, that is, by increasing the F value. 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 the R, G, and B lights have almost the same operation, the modulation system of the 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 (a) and (b)), the scattering and transmission state of incident light are controlled by a signal applied to the pixel electrode to modulate the light.

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.

The above-mentioned liquid crystal projection television was constructed and displayed an image. When the contrast was 150, the screen gain was 5, and the screen size was 40 inches, the center luminance was 18
0 (ft-L).

In FIG. 5, the projection lens system is not limited to this. For example, a central shielding type optical system that shields a parallel light component with a light shield and projects scattered light on a screen may be used. It goes without saying that it is good.

Further, 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 present 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 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 input to 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 liquid crystal panel of the present invention has been described as a transmissive liquid crystal panel, the present invention is not limited to this, and the liquid crystal panel may be formed in a reflective type. In such a case, the pixel electrode and the like may be formed as a reflective electrode using a metal material. When a projection type television is configured using a reflection type liquid crystal panel, it may be configured as shown in FIG. Incidentally, in FIG.
It is clean.

[0055]

As described above, the liquid crystal panel of the present invention can obtain a high-luminance screen twice or more as compared with the liquid crystal panel using the TN liquid crystal by using the polymer dispersed liquid crystal.

Further, by arranging or forming a microlens on the incident light side of the liquid crystal panel and optimizing the plate thickness of the counter electrode substrate, the light utilization efficiency of the incident light is remarkably improved.

Further, a light shielding film such as a TFT is formed on a microlens substrate or the like to prevent photocontamination, and a low dielectric film is formed in the liquid crystal layer to prevent image noise from being seen. I have.

Further, the liquid crystal projection television realizes high contrast and high brightness display by employing the liquid crystal panel according to the present invention .

[Brief description of the drawings]

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

FIG. 2 is a partial cross-sectional view of a liquid crystal panel according to a second embodiment of the present invention.

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

FIG. 4 is a partial sectional view of a liquid crystal panel according to a fourth 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 explanatory diagram of a spread angle of light.

FIG. 8 is an equivalent circuit diagram of a liquid crystal panel.

FIG. 9 is a sectional view of a conventional liquid crystal panel.

FIG. 10 is a configuration diagram of a conventional liquid crystal projection television.

FIG. 11 is an explanatory diagram of an operation of a polymer dispersed liquid crystal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Micro lens board 12 Array board 13 Space board 14 Micro lens 15 Adhesive layer 16 Counter electrode 18 Source signal line 19 Pixel electrode 20 Liquid crystal layer 21, 43 Light shielding film 22 TFT 31 Low dielectric constant film 41 Resin layer 42 Spacer 54a, 54b, 54c Polymer dispersed liquid crystal panel 71 Principal ray 96 TN liquid crystal 97a, 97b Alignment film 98 Black matrix 105a, 105b, 105c TN liquid crystal panel 114 Water droplet liquid crystal 115 Polymer

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshimasa Fushimi 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-248125 (JP, A) JP-A-4- 180020 (JP, A) JP-A-3-51817 (JP, A) JP-A-2-302726 (JP, A) JP-A-1-18985 (JP, A)

Claims (8)

(57) [Claims] A first substrate on which pixel electrodes arranged in a matrix, a switching element for applying a signal to the pixel electrodes, and a signal line disposed between the pixel electrodes are formed; and a counter electrode is formed. A second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, on the switching element, on the signal line, on the counter electrode facing the switching element, and on the At least one portion of the counter electrode facing the signal line is made of a light-transmitting material having a dielectric constant lower than the dielectric constant of the liquid crystal layer, and is patterned in accordance with the pixel pattern. A liquid crystal panel having a body film formed thereon. 2. A first substrate on which pixel electrodes arranged in a matrix, switching elements for applying signals to the pixel electrodes, and signal lines arranged between the pixel electrodes are formed, and a counter electrode is formed. A second substrate, a third substrate on which micro lenses are regularly formed corresponding to the positions of the pixel electrodes, and a third substrate sandwiched between the first substrate and the second substrate. A liquid crystal layer having a lower dielectric constant than the liquid crystal layer on at least one of the switching element, the signal line, the counter electrode facing the switching element, and the counter electrode facing the signal line; A liquid crystal panel comprising a dielectric film made of a light transmissive material having a dielectric constant and patterned in correspondence with a pixel pattern. 3. A first substrate on which pixel electrodes arranged in a matrix and switching elements connected to the pixel electrodes are formed; a second substrate on which a counter electrode is formed; A third substrate on which micro lenses are formed correspondingly regularly; a liquid crystal layer sandwiched between the first substrate and the second substrate; a third substrate and the second substrate; A transparent material filled between the substrate and the switching element, on the signal line, on at least one location on the counter electrode facing the switching element and on the counter electrode facing the signal line, A light-transmitting material having a dielectric constant lower than that of the liquid crystal layer, and a dielectric film patterned in accordance with a pixel pattern; and a length obtained by averaging the horizontal length and the vertical length of the pixel. A age,
A liquid crystal panel wherein the value of b / a is 3 or more and 8 or less, where b is the focal length of the microlens. 4. A first substrate on which pixel electrodes arranged in a matrix are formed; a second substrate on which a counter electrode is formed; and micro lenses regularly arranged corresponding to the positions of the pixel electrodes. A third substrate formed, a polymer-dispersed liquid crystal layer sandwiched between the first substrate and the second substrate, and a filling material between the third substrate and the second substrate And a light-shielding film formed on a surface of the second substrate and in contact with the transparent material or on a surface of the third substrate and in contact with the transparent material. A liquid crystal panel, wherein a ratio of a liquid crystal material in the liquid crystal layer is 50% by weight or more and 90% by weight or less, and a film thickness of the polymer dispersed liquid crystal layer is 8 μm or more and 15 μm or less. 5. A first substrate on which pixel electrodes are arranged in a matrix, a second substrate on which a counter electrode is formed, and microlenses formed regularly corresponding to the positions of the pixel electrodes. A third substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, a transparent material for bonding the third substrate and the second substrate, A liquid crystal panel comprising: a light-shielding film formed on the surface of the substrate and in contact with the transparent material or on the surface of the third substrate in contact with the transparent material. 6. The liquid crystal panel according to claim 1, light generating means having an arc discharge lamp, an optical member for guiding light emitted by the light generating means to the liquid crystal panel, and displaying an image on the liquid crystal panel. A projection display device, comprising: projection means for projecting. 7. The liquid crystal panel according to claim 2, light generating means having an arc discharge lamp, an optical member for guiding light emitted by the light generating means to the liquid crystal panel, and displaying an image on the liquid crystal panel. A projection display device, comprising: projection means for projecting. 8. A liquid crystal panel according to claim 5, light generating means having an arc discharge lamp, an optical member for guiding light emitted by the light generating means to the liquid crystal panel, and a display image of the liquid crystal panel. A projection display device, comprising: projection means for projecting.