JPH04309922A - Liquid crystal panel and its manufacture, and liquid crystal projection type television - Google Patents

Abstract

PURPOSE:To provide a polymer dispersed liquid crystal panel which has an excellent scattering characteristic in a wide wavelength range. CONSTITUTION:Polymer dispersed liquid crystal layers 15a and 15b are formed between upper and lower array substrates 13a and 13b and a counter electrode layer 14 is formed in the middle between the liquid crystal layers 15a and 15b. The mean particle size of water drop type liquid crystal of the polymer dispersed liquid crystal layer 15a is made different from that of the polymer dispersed liquid crystal layer 15b. The particle sizes are adjusted with the intensity of ultraviolet rays at the time of the setting of the liquid crystal layers or by using a polymer material. The scattering characteristic depends upon the mean particle size of the water drop type liquid crystal and water drop type liquid crystal having two kinds of particle size is formed in one panel to improve the scattering characteristic in the wide wavelength range and also obtain the excellent contrast.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is primarily concerned with projection televisions (hereinafter referred to as liquid crystal projection televisions) that enlarge and project images displayed on a small liquid crystal panel onto a screen, and liquid crystal panels used in said liquid crystal projection televisions. and its manufacturing method.

0002

2. Description of the Related Art Liquid crystal display devices have many characteristics such as being lightweight and thin, and therefore research and development are active. However, there are many problems, such as difficulty in increasing the screen size. Therefore, in recent years,
2. Description of the Related Art Liquid crystal projection televisions, which enlarge and project images displayed on a small liquid crystal panel using a projection lens or the like, are suddenly attracting attention. Currently, liquid crystal projection televisions on the market use twisted nematic (hereinafter referred to as TN) liquid crystal display devices that utilize the light distribution characteristics of liquid crystals.

First, a general liquid crystal panel will be explained. (FIG. 9) is a plan view of the liquid crystal panel. (FIG. 9), 93 is a glass substrate (hereinafter referred to as an array substrate) on which thin film transistors (hereinafter referred to as TFTs) and the like as switching elements are formed, and 94 is a substrate (hereinafter referred to as an array substrate) on which transparent electrodes made of ITO or the like are formed. 91 is a drive IC (hereinafter referred to as gate drive IC) that applies a signal to control the on/off of the TFT connected to the gate signal line on the array substrate 93; 92 is on the array substrate 93; A drive IC (hereinafter referred to as source drive IC) for applying a data signal to the source signal line of
, 95 is a polarizing film, and 96 is a sealing resin.

FIG. 10 is an equivalent circuit diagram of an image display section of an array substrate 93 constituting a liquid crystal panel. (FIG. 10), 101 is a gate drive circuit, 102
is the source drive circuit, G1 to Gm are the gate signal lines, and S
1 to Sn are source signal lines, 103 is a TFT, 104 is an additional capacitor, and 105 is a liquid crystal as a display element.

In operation of the liquid crystal panel, the gate drive circuit 101 sequentially applies on-voltage to the gate signal lines G1 to Gm. At the same time, source drive circuit 1
02 outputs a voltage to be applied to each pixel to the source signal lines S1 to Sn. A voltage that makes the liquid crystal transmit a predetermined amount of light is applied to each display element 105 and maintained. This voltage is maintained until each TFT is turned on again in the next cycle. By repeating the above operations, the light is modulated and an image is displayed.

A conventional liquid crystal display device will be explained below. (FIG. 11) is a plan view of a display area of a conventional liquid crystal display device. (FIG. 11), 114a and 114b are source signal lines, 113a and 113b are gate signal lines, and 1
11 is a pixel electrode, and 112 is a TFT formation position. Moreover, (FIG. 12) is a sectional view taken along the line AA' of (FIG. 11). However, in order to simplify the explanation, unnecessary parts are omitted. In FIG. 12, 125 is a pixel electrode, 126 is a counter electrode made of ITO, 123 is a TN liquid crystal, 122 is an array substrate on which TFTs, signal lines, etc. are formed, 121 is a counter substrate, and 124 is a TFT. As is clear from FIGS. 11 and 12, in the conventional liquid crystal panel, a TFT is formed to control the signal applied to the pixel electrode 111 for each pixel, and the counter substrate 1
A counter electrode 126 is formed on 21. Further, the counter substrate 121 and the array substrate 122 are usually arranged at an interval of 4 to 6 μm, the peripheral part of the liquid crystal panel is sealed with a sealing resin 96 as shown in FIG. 9, and a TN liquid crystal is placed in the interval. It has an injected structure.

A conventional method for manufacturing a liquid crystal panel will be described below with reference to the drawings. In addition, (Figure 13(a)
) to (e)) are explanatory diagrams for explaining a conventional method of manufacturing a liquid crystal panel. In (FIG. 13), 131 is a sealing resin. First, as shown in (Fig. 13(a)), T
The array substrate 122 on which the FT 124 and the pixel electrode 125 are formed is arranged with the element surface facing upward. Next (Figure 1
As shown in 3(b)), a sealing resin 131 is applied to the periphery of the display area using a screen printing technique or the like. On the other hand, on the counter substrate 121, beads 23 are scattered on the counter electrode 126 to obtain a predetermined gap of the liquid crystal layer, as shown in FIG. 13(c). Thereafter, as shown in FIG. 13(d), the array substrate 122 is positioned on the counter substrate 121, and the array substrate 122 and the counter substrate 121 are bonded together. Thereafter, the sealing resin is cured by heating or irradiating with ultraviolet rays. Next, the substrate is placed in a vacuum chamber to create a vacuum in the gap between the array substrate 122 and the counter substrate 121, and then the liquid crystal injection port is inserted into the liquid crystal. Thereafter, when the vacuum in the vacuum chamber is broken, the TN liquid crystal 123 is injected into the gap from the injection port. Finally, seal the injection port (Figure 13 (
The liquid crystal panel is completed as shown in e)).

[0008] Hereinafter, a conventional liquid crystal projection type television will be explained with reference to the drawings. (FIG. 14) is a configuration diagram of a conventional liquid crystal projection television. (Figure 14), 14
1 is a condensing optical system, 142 is an infrared cut mirror that transmits infrared rays, 143a is a blue light reflecting dichroic mirror (hereinafter referred to as BDM), 143b is a green light reflecting dichroic mirror (hereinafter referred to as GDM), and 143c is red Light reflecting dichroic mirror (hereinafter referred to as RDM), 144a, 144b, 144c, 146a, 146
b, 146c are polarizing plates, 145a, 145b, 145c
are transmission type TN liquid crystal display devices, 147a, 147b, 1
47c is a projection lens system. Note that the projection lens system is generally referred to as a projection lens unless otherwise noted. Also,
Components unnecessary for explanation, such as a field lens, are omitted from the drawings.

The operation of a conventional liquid crystal projection television will be described below with reference to FIG. 14. First, from the white light emitted from the condensing optical system 141, blue light (hereinafter referred to as B light) is reflected by the BDM 143a, and this B light is incident on the polarizing plate 144a. Similarly, the green light (hereinafter referred to as G light) of the light transmitted through the BDM 143a is reflected by the GDM 143b and transmitted to the polarizing plate 144b.
Red light (hereinafter referred to as R light) is reflected by the polarizing plate 144c and enters the polarizing plate 144c. The polarizing plate allows only one of the longitudinal wave component and the transverse wave component of each color light to pass through, aligning the polarization direction of the light and irradiating each liquid crystal display device. At this time, 5
0% or more of the light is absorbed by the polarizing plate, and the brightness of the transmitted light is less than half at most.

[0010] Each liquid crystal display device modulates the transmitted light using a video signal. The modulated light passes through each polarizing plate 146a, 146b, 146c depending on the degree of modulation, enters each projection lens system 147a, 147b, 147c, and is enlarged and projected onto a screen (not shown) by these lenses. .

[0011]

As is clear from the above description, in a liquid crystal panel using TN liquid crystal, it is necessary to input light into linearly polarized light. Therefore, it is necessary to arrange polarizing plates before and after the liquid crystal display device. The aforementioned polarizing plate theoretically absorbs more than 50% of the light. Therefore, there is a problem that only low screen brightness can be obtained when enlarging and projecting onto a screen.

In order to solve the above problems, the liquid crystal panel and liquid crystal projection television of the present invention use polymer dispersed liquid crystal. Polymer-dispersed liquid crystals can be roughly divided into two types depending on the state of dispersion of the liquid crystal and polymer. One is a type in which droplet-shaped liquid crystals are dispersed in a polymer. Liquid crystals exist in a discontinuous state in polymers. From then on,
Such a liquid crystal is called a PDLC, and a liquid crystal panel using the liquid crystal is called a PD liquid crystal panel. The other is
This type has a structure in which a polymer network is stretched around the liquid crystal layer. It looks like a sponge soaked in liquid crystal. The liquid crystal does not form in the form of water droplets but exists continuously. Hereinafter, such a liquid crystal will be referred to as PNLC, and a liquid crystal panel using the liquid crystal will be referred to as a PN liquid crystal panel. Images are displayed on the two types of liquid crystal panels by controlling scattering and transmission of light. PDLC utilizes the property that the refractive index differs depending on the direction in which liquid crystal is oriented. When no voltage is applied, each droplet-like liquid crystal is oriented in an irregular direction. In this state,
There is a difference in refractive index between the polymer and the liquid crystal, and the incident light is scattered. If a voltage is applied here, the alignment direction of the liquid crystals will be aligned. If the refractive index when the liquid crystal is oriented in a certain direction is matched with the refractive index of the polymer in advance, the incident light will be transmitted without being scattered.

On the other hand, PNLC uses the irregular alignment of liquid crystal molecules itself. In an irregularly oriented state, that is, in a state where no voltage is applied, incident light is scattered. On the other hand, if a voltage is applied to make the arrangement regular, light will pass through. Note that the above-mentioned explanation of the movement of liquid crystals in PDLC and PNLC is merely a model concept. Although the present invention is not limited to one of the PD liquid crystal panel and the PN liquid crystal panel, for ease of explanation, the PD liquid crystal panel
This will be explained using a liquid crystal panel as an example. Further, PDLC and PNLC are collectively referred to as polymer-dispersed liquid crystal, and PD liquid crystal panels and PN liquid crystal panels are collectively referred to as polymer-dispersed liquid crystal panel. Further, a liquid containing liquid crystal to be injected into a polymer-dispersed liquid crystal panel is collectively called a liquid crystal solution or a resin, and a state in which the resin component of the liquid crystal solution is polymerized and hardened is called a polymer.

First, the operation of polymer-dispersed liquid crystal will be briefly described using FIGS. 15(a) and 15(b). (Figure 15 (
a) and (b)) are explanatory diagrams of the operation of the polymer dispersed liquid crystal display device. (FIGS. 15(a) and 15(b)), 151 is an array substrate, 152 is a pixel electrode, 153 is a counter electrode, 15
4 is a droplet-shaped liquid crystal, 155 is a polymer, and 156 is a counter substrate. A TFT or the like is connected to the pixel electrode 152, and the TF
A voltage is applied to the pixel electrode by turning on and off T, changing the alignment direction of the liquid crystal on the pixel electrode and modulating light. As shown in FIG. 15(a), when no voltage is applied, each droplet-like liquid crystal 154 is oriented in an irregular direction. In this state, there is a difference in refractive index between the polymer 155 and the liquid crystal, and the incident light is scattered. Here (Fig. 15(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 matched with the refractive index of the polymer in advance, the incident light will be emitted from the array substrate 151 without being scattered.

As mentioned above, the polymer-dispersed liquid crystal displays an image by scattering light with the droplet-like liquid crystal or by transmitting light through the droplet-like liquid crystal. However, there is a close relationship between the shape of the droplet-like liquid crystal and the wavelength of the scattered light. When the particle size of the droplet-like liquid crystal is large, short wavelength light is difficult to be scattered. On the other hand, if it is small, light with long wavelengths is less likely to be scattered. In PNLC, the average void spacing of the polymer (hereinafter referred to as pore size)
The light scattering characteristics are determined by the size. therefore,
It is difficult to satisfactorily modulate light of wavelengths in all regions of blue, green, and red light with the same particle size or pore size of droplet-like liquid crystal.

[0016]

[Means for Solving the Problems] In order to solve the above-mentioned problems, a liquid crystal panel according to a first aspect of the present invention includes polymer-dispersed liquid crystals arranged in first and second array substrates, and A transparent electrode layer is formed in between. The average particle size or pore size of the droplet-like liquid crystal is changed by changing the polymer or liquid crystal material of the upper and lower layers of the transparent electrode layer, or by changing the ultraviolet irradiation conditions.

In the liquid crystal panel of the second aspect of the present invention, a first polymer-dispersed liquid crystal layer is formed between the first array substrate and a glass substrate having transparent electrodes formed on both sides, and a first polymer-dispersed liquid crystal layer is formed between the second array substrate and the glass substrate having transparent electrodes formed on both sides. A second polymer-dispersed liquid crystal layer is formed between the glass substrates. In the first and second polymer-dispersed liquid crystal layers, the average particle size or pore size of the droplet-like liquid crystal is changed by changing the polymer or liquid crystal material, or by changing the ultraviolet irradiation conditions.

[0018] The first method for manufacturing a liquid crystal panel of the present invention includes:
A resin containing liquid crystal is applied onto a first substrate on which an active element is provided for each pixel electrode, and the resin is cured. Next, a transparent electrode is formed on the upper layer of the cured resin, and a transparent electrode is formed on the cured resin. A second substrate on which an active element is provided for each pixel electrode is held on the electrode at a predetermined interval, and after injecting a resin containing liquid crystal between the transparent electrode and the second substrate, at least one of light or heat is applied. The method is characterized in that the resin is cured by irradiating one side onto the resin.

[0019] The second method of manufacturing a liquid crystal panel of the present invention includes:
A second substrate having transparent properties and having transparent electrodes formed on both sides is held at a predetermined interval on a first substrate on which an active element is provided for each pixel electrode, and a pixel electrode is placed on the second substrate. A third substrate provided with an active element was held at a predetermined distance from each other, and a resin containing liquid crystal was injected between the first substrate and the second substrate and between the second substrate and the third substrate. After that, the resin is irradiated with at least one of light and heat to harden the resin.

[0020] The liquid crystal projection television of the present invention has three polymer dispersed liquid crystal panels that modulate light in three regions of red light, green light, and blue light, and one liquid crystal panel in particular for modulating red light. The liquid crystal panel according to the first or second aspect of the present invention is used in the polymer-dispersed liquid crystal panel shown in FIG.

[0021]

[Operation] The liquid crystal panel of the present invention has a polymer-dispersed liquid crystal layer having a two-layer structure in which droplet-like liquid crystal particles have different average particle diameters or pore diameters. When the average particle size or pore size of the droplet-like liquid crystal is small, the scattering properties at short wavelengths are good, and when the average particle size or pore size is large, the scattering properties at long wavelengths are good. The average particle size or pore size of one of the polymer fraction liquid crystal layers of the present invention is larger than that of the other layer. Therefore, it is possible to satisfactorily modulate light in a wide wavelength range from the short wavelength of blue light to the long wavelength of red light. Furthermore, each polymer-dispersed liquid crystal layer is sandwiched between a pixel electrode and a counter electrode, making it easy to apply voltage to the liquid crystal, and the response speed of the liquid crystal is as fast as 20 milliseconds or less.

Furthermore, the method for manufacturing a liquid crystal panel of the present invention is for manufacturing the liquid crystal panel of the present invention. Even though these devices form two polymer-dispersed liquid crystal layers, it is possible to easily manufacture a liquid crystal panel.

[0023] Since the present invention uses a polymer-dispersed liquid crystal, it is possible to achieve screen brightness that is more than twice as high as that of conventional liquid crystal projection televisions. Furthermore, polymer-dispersed liquid crystal panels have poor scattering properties, especially in the long wavelength region such as red light, and when a projection television is constructed using the liquid crystal panel, there is a problem of low contrast. By using the panel for modulating red light, the scattering properties are good in all wavelength regions, and a contrast of 200:1 or more can be achieved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal panel according to the first aspect of the present invention will be described below with reference to the drawings. (FIG. 1) is a sectional view of a liquid crystal panel according to the first aspect of the present invention. (Figure 1), 13a
, 13b are array substrates, 12a and 12b are pixel electrodes, 1
1a, 11b are TFTs, 14 is a counter electrode, 15a, 15
b is a polymer-dispersed liquid crystal layer. As is clear from FIG. 1, the polymer-dispersed liquid crystal layer 13a is sandwiched between the array substrate 13a and the counter electrode 14, and the polymer-dispersed liquid crystal layer 13b is sandwiched between the array substrate 13b and the counter electrode 14. . The thickness of the liquid crystal layer is 5 to 20 μm, especially 8 to 12 μm.
m is around good. The pixel electrodes 12a and 12b are arranged at opposing positions and configured to allow light to pass through them smoothly. The counter electrode 14 is configured so that a common voltage is electrically applied to the peripheral portion of the substrate, similar to a conventional liquid crystal panel. A more detailed explanation will be given below regarding the first method of manufacturing a liquid crystal panel of the present invention.

The method for manufacturing a liquid crystal panel according to the first aspect of the present invention will be explained below. The first method of manufacturing a liquid crystal panel according to the present invention is the method of manufacturing a liquid crystal panel shown in FIG. 1.

(FIGS. 2A to 2E) are explanatory diagrams for explaining the method of manufacturing a liquid crystal panel according to the first aspect of the present invention. (In FIGS. 2(a) to (e)), 21 is the fluororesin 2
2 is a coated glass substrate, and 23 is a bead.

First, a liquid crystal solution is applied onto the array substrate 13a. The liquid crystal solution contained 10 parts of trimethylolpropane triacrylate, 10 parts of 2-hydroxyethyl acrylate, 23 parts of acrylic oligomer ("M-1200" manufactured by Toagosei Kagaku Co., Ltd.), and Merck & Co., Ltd. as a photocuring initiator. 0.0.
5 parts and 50 parts of "E7" manufactured by BDH as a liquid crystal.

Application methods include printing techniques such as screen printing, and methods using a spinner. The best liquid crystal for the liquid crystal solution is cyanobiphenyl, and the best resin is acrylic. The liquid crystal solution used has a volume ratio of resin to liquid crystal of 10:1 to 1:10, especially 2:
A ratio of 1 to 1:2 is appropriate. Beads may be dispersed in the liquid crystal solution. The liquid crystal solution is degassed before application.

The beads 23 used have a diameter of 5 to 30 μm, preferably 10 to 20 μm. Further, the beads may be scattered on the array substrate 13a in advance. After being left for a predetermined period of time, the resin is phase-separated by irradiation with ultraviolet rays. Furthermore, in order to further improve the smoothness, there is also a method in which, after applying the liquid crystal solution, a glass substrate 21 coated with a fluororesin 22 is placed on top of the liquid crystal solution. At this time, stack the array substrates from the edge to prevent air from entering. The state at that time is shown in (Figure 2).

Next, pressure is applied from above the glass substrate 21 so that the distance between the glass substrate 21 and the array substrate 13a is equal to the diameter of the beads. As a method of applying pressure, there is a method of applying pressure from the edge of the substrate using a roller or the like. Next, when ultraviolet rays are irradiated from the glass substrate 21 side, only the photocurable resin in the liquid crystal solution is cured, phase separation occurs, and water droplet-like liquid crystals are formed.

The state of the droplet-like liquid crystal is determined by the mixing ratio of the liquid crystal and the resin, and when the liquid crystal is less than 50% by weight, it becomes a spherical liquid crystal droplet that exists independently in the polymer matrix, and when it is more than 50% by weight, the liquid crystal droplets form spherical liquid crystal droplets that exist independently within the polymer matrix. are connected to form a continuous phase and form a three-dimensional network structure. Furthermore, the average particle diameter or average gap spacing of the liquid crystal droplets is determined by the intensity of the ultraviolet rays irradiated when forming the polymer matrix. In the present invention, the polymer-dispersed liquid crystal layer 15a was cured by irradiation using a metal halide lamp with an intensity of 90 W/cm at a belt conveyor speed of 3 m/min. The average particle diameter of the liquid crystal droplets of the polymer-dispersed liquid crystal panel thus obtained was about 1.2 μm.

After curing as described above, if the glass substrate 21 is used, the glass substrate 21 is peeled off and removed. At this time, since the fluororesin has good releasability, it can be easily peeled off by applying pressure to the edge of the glass substrate 21. next,
A light-transmissive thin film, for example, an ITO thin film 14, is formed on the polymer-dispersed liquid crystal layer 15a. This becomes the counter electrode or common electrode. This state is shown in (FIG. 2(d)). Note that the ITO thin film may be a SnO2 thin film.

Next, beads 23 are scattered on the counter electrode. On the other hand, a sealing resin is applied to the periphery of the array substrate 13b, and the array substrate 13a on which the counter electrode 14 is formed and the array substrate 13b are bonded together. At this time, the opposing pixel electrodes 12a and 12b are fitted so that they overlap vertically with high precision. Thereafter, the sealing resin is cured by heating or irradiating with ultraviolet rays. Next, the substrate is placed in a vacuum chamber to create a vacuum between the array substrate 13b and the counter electrode 14, and then the liquid crystal injection port is immersed in the liquid crystal solution shown above. Thereafter, when the vacuum in the vacuum chamber is broken, the liquid crystal solution is injected between the array substrate 13b and the counter electrode 14. Thereafter, the liquid crystal solution was cured by irradiation using a metal halide lamp with an intensity of 50 W/cm at a belt conveyor speed of 2 m/min. The average particle diameter of the droplet-like liquid crystal in the polymer-dispersed liquid crystal layer 15b thus obtained was about 2.0 μm. The liquid crystal panel completed as described above is shown in FIG. 2(e).

The liquid crystal panel according to the second aspect of the present invention will be explained below with reference to the drawings. (FIG. 3) is a sectional view of the liquid crystal panel of the second invention. In (Figure 3), 31
31b are counter electrodes formed on both sides of a counter substrate 32 made of glass. The thickness of the counter substrate 32 is 1.2 m
m or less, preferably 0.8 mm or less. The film thickness of the polymer-dispersed liquid crystal layers 15a, 15b is preferably 5 to 20 μm, and preferably 8 to 12 μm. As is clear from FIG. 3, the polymer-dispersed liquid crystal layer 15a is
a and the counter electrode 31a, the polymer-dispersed liquid crystal layer 15
b is sandwiched between the array substrate 13b and the counter electrode 31b. The pixel electrodes 12a and 12b are arranged at vertically opposing positions, and are configured to allow light to pass through them smoothly when the polymer-dispersed liquid crystal layers 15a and 15b are in a transmitting state. The opposing electrodes 31a and 31b are configured such that a common voltage is electrically applied to the peripheral portion of the substrate. A more detailed explanation will be given below regarding the second method of manufacturing a liquid crystal panel of the present invention.

The method for manufacturing a liquid crystal panel according to the second aspect of the present invention will be explained below. The second method of manufacturing a liquid crystal panel according to the present invention is the method of manufacturing a liquid crystal panel shown in FIG. 3. (FIGS. 4(a) to 4(e)) are diagrams for explaining the method for manufacturing a liquid crystal panel according to the second aspect of the present invention. In (FIG. 4), 41a and 41b are sealing resins. First, a sealing resin 41a is applied to the periphery of the array substrate 13a using a method such as screen printing. This state is shown in FIG. 4(b).

On the other hand, the beads 23 are scattered on the counter substrate 32, and the beads 23 are also spread on the array substrate 13b at the same time as the sealing resin 41b is applied. This state (Fig.
c)). Next, the opposing substrate 32 and the array substrate 13a are aligned and bonded together. Further, the substrate and the array substrate 13b are also aligned and pressurized. Thereafter, the sealing resins 41a and 41b are cured by heating or irradiating with ultraviolet rays. The state is shown in FIG. 4(d). Next, the substrate is placed in a vacuum chamber to create a vacuum between the array substrate and the counter substrate, and then the liquid crystal injection port is immersed in the liquid crystal solution shown in the first method of manufacturing a liquid crystal panel of the present invention. Thereafter, when the vacuum in the vacuum chamber is broken, the liquid crystal solution is injected between the substrates. Finally, ultraviolet rays are irradiated for 30 seconds using a metal halide lamp with an intensity of 100 W/cm from above and a metal halide lamp with an intensity of 50 W/cm from below. Then, the average particle diameter of the droplet-like liquid crystal in the polymer-dispersed liquid crystal layer 15a is approximately 1.
．． 2 μm, and the average particle diameter of the droplet-like liquid crystal in the polymer-dispersed liquid crystal layer 15b was about 2.0 μm. Although the ultraviolet rays are irradiated from above and below the substrate, the present invention is not limited to this, and the irradiation may be performed only from above. In this case, the light from above is attenuated by the pixel electrode 12a, the counter electrode 31a, etc., and the polymer-dispersed liquid crystal layer 15b is hardly irradiated. Therefore, the average particle size of the droplet-like liquid crystal becomes large.

The liquid crystal projection television of the present invention will be explained below with reference to the drawings. (FIG. 5) is a configuration diagram of a liquid crystal projection television according to the present invention. However, components unnecessary for explanation are omitted. In FIG. 5, 51 is a condensing optical system, which includes a concave mirror and a 250W metal halide lamp serving as a light generating means. Further, the concave mirror is configured to reflect only visible light. Further, an ultraviolet cut filter is arranged at the output end of the condensing optical system 51. 52 is an infrared cut mirror that transmits infrared rays and reflects only visible light. However, it goes without saying that the infrared cut mirror 52 may be arranged inside the condensing optical system 51. Further, 53a is a blue dichroic mirror (hereinafter referred to as BDM), 53b is a green dichroic mirror (hereinafter referred to as GDM), 5
3c is a red dichroic mirror (hereinafter referred to as RDM). Note that the arrangement of the BDM 53a to RDM 53c is not limited to the order shown in FIG. 5, and it goes without saying that the last RDM 53c may be replaced with a total reflection mirror.

54a, 54b and 54c are polymer-dispersed liquid crystal panels, particularly 54c is the polymer-dispersed liquid crystal panel of the first or second invention. In order to prevent halation and reflection of light, the liquid crystal panel has an antireflection film formed on at least the light incident surface. 55a, 5
5b and 55c are lenses, 57a, 57b and 57
c is a projection lens, and 56a, 56b and 56c are apertures serving as apertures. In addition, 55, 56 and 5
7 constitutes a Schlieren optical system. Further, unless there is a particular problem, the set of 55, 56 and 57 will be referred to as a projection lens system. Also, the aperture is the FNo. of the lens 55. It is clear that this is not necessary when is large.

The arrangement of the projection lens system is as follows. First, the distance L between the polymer dispersed liquid crystal panel 54 and the lens 55 and the distance between the lens 55 and the aperture 56 are arranged so that they are approximately equal. Further, the lens 55 is selected to have a condensing angle θ of about 6 degrees or less. Further, the opening diameter D of the aperture 56 is set to about 1 cm, assuming that the distance L mentioned above is 10 cm. The projection lens system as described above has the role of transmitting parallel light rays that have passed through each liquid crystal panel and transmitting light scattered by each liquid crystal panel. As a result, a high-contrast, full-color display can be realized on the screen. Contrast can be improved by reducing the opening diameter D of the aperture. However, the image brightness on the screen will decrease.

The thickness of the liquid crystal layer of the polymer dispersed liquid crystal panel is
When the diameter is 10 to 15 μm, the convergence angle θ of the lens is at least 8
It needed to be lower than that. Above all, around 6 degrees is optimal, and at that time, the contrast is 200:1 at the center of the screen, and when projecting on a 40-inch screen with a screen gain of 5 using the rear method, a brightness of 400 ft can be achieved, making it comparable to a CRT projection TV. In comparison, we were able to obtain even higher screen brightness. Note that the opening diameter of the aperture at that time was 10 mm, and the distance L was approximately 100 mm. Furthermore, the average particle diameter of the droplet-like liquid crystal of the polymer dispersed liquid crystal panel used in the liquid crystal projection type television of the present invention is as follows:
About 1.0 μm for 54b. The liquid crystal panel 54c has a two-layer structure, with a thickness of 1.2 μm and a thickness of 2.0 μm, respectively.
It was 0 μm. The liquid crystal panels 54a and 54b had very good scattering properties from blue light to green light, and the liquid crystal panel 54c had good scattering properties over a wide range from green light to red light.

The operation of the liquid crystal projection television according to the present invention will be explained below. Note that since the modulation systems for R, G, and B lights operate almost the same, the modulation system for B light will be explained as an example. First, white light is emitted from the condensing optical system 55, and the B light component of the white light is transmitted to the BDM 53a.
reflected by. The B light is transmitted through the polymer dispersed liquid crystal panel 5.
4a. The polymer dispersed liquid crystal panel (Figure 15
), the scattering and transmission of the incident light is controlled by the signal applied to the pixel electrode, and the light is modulated. Scattered light is blocked by the aperture 56a, while parallel light or light within a predetermined angle passes through the aperture 56a. The modulated light is enlarged and projected onto a screen (not shown) by a 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 G light component, and the polymer-dispersed liquid crystal panel 54c modulates the R light component, so that a color image is displayed on the screen.

The driving circuit and driving method for a liquid crystal projection television according to the present invention will be explained below. (FIG. 6) is an explanatory diagram of a drive circuit for a liquid crystal projection television according to the present invention. (Figure 6
), 54c is a liquid crystal panel that modulates R light;
b is a liquid crystal panel that modulates G light, 54a is a liquid crystal panel that modulates B light, and R1 and R2 and transistor Q
This constitutes a phase dividing circuit that creates positive and negative polarity video signals for the video signal input to the base. 61a,
Reference numerals 61b and 61c are output switching circuits that output AC video signals whose polarities are inverted for each field to the liquid crystal panel. After the video signal is gain-adjusted to a predetermined value, it is divided into signals corresponding to R, G, and B lights. These video signals are respectively video signal (R) and video signal (G).
, video signal (B). Each video signal (R
), (G), and (B) are input to a phase division circuit, and this circuit produces two video signals of positive polarity and negative polarity.

Next, the three video signals are input to respective output switching circuits 61a, 61b, and 61c, and the circuits output video signals whose polarities are inverted for each field. The reason why the polarity is inverted for each field is to prevent deterioration of the liquid crystal by applying an alternating current voltage to the liquid crystal, as described above. Next, the video signals output from the respective output switching circuits are input to a source drive IC (not shown). A control circuit (not shown) synchronizes the source drive IC and gate drive IC (not shown) to display an image on the liquid crystal panel.

Next, the visibility of the human eye will be explained. The human eye has the highest sensitivity around a wavelength of 555 nm. Of the three primary colors of light, green is the most sensitive, followed by red, and blue is the least sensitive. In order to obtain a luminance signal proportional to this sensitivity, it is sufficient to add 30% red, 60% green, and 10% blue. Therefore, to obtain white color in television images, it is sufficient to add R:B:G at a ratio of 3:6:1. Furthermore, as mentioned earlier, the liquid crystal needs to be driven with alternating current. The AC driving is performed by alternately applying positive and negative polarity signals to a voltage applied to the opposing electrode of the liquid crystal panel, that is, a common voltage. In this example, a positive polarity signal is applied to the liquid crystal panel to modulate light with an intensity of visibility n, and a negative polarity signal is applied to modulate light with an intensity of visibility n. The current state is expressed as -n.

For example, a liquid crystal panel is irradiated with light of R:G:B=3:6:1, a positive polarity signal is applied to the R and B liquid crystal panels, and a negative polarity signal is applied to the G liquid crystal panel. If a positive signal is applied, it is expressed as +3, -6, and +1. In addition, R:G:B=3:6:1 is NTSC
In the case of a television image, the above ratio differs depending on the characteristics of the lamp and dichroic mirror of the light source in the case of a liquid crystal projection television. (Figure 6) +3, -6, +1
As shown, the light of R:G:B=3:6:1 is irradiated, and the positive polarity signal is applied to the R and B liquid crystal panels, and the negative polarity signal is applied to the G liquid crystal panel. It shows where it is being done. After one field, the signal application state is expressed as -3, +6, and -1.

(FIG. 7) shows the waveform of the signal applied to each liquid crystal panel. (Figure 7(a)) shows the liquid crystal panel 5 that modulates the R light.
4c, (FIG. 7(b)) is the signal waveform of the liquid crystal panel 54b that modulates the G light, and (FIG. 7(c)) is the signal waveform of the liquid crystal panel 54c that modulates the B light. (Figure 7(a)
As is clear from (b) and (c), the signal waveform for G light modulation has the opposite polarity to the signal waveform for R and B light modulation. Normally, even when the same signal is applied to a liquid crystal panel, there is a slight difference in the voltages held in pixels between even and odd fields. This occurs because the on-current and off-current of the TFT differ depending on the polarity of the video signal, or because the retention characteristics of an alignment film or the like between a positive electric field and a negative electric field are different. This difference causes a phenomenon called flicker. However, in the LCD projection type television of the present invention, as shown in FIG. 7, by making the signal for G light modulation have the opposite polarity to the signals for R and B light modulation, flicker is prevented from appearing visually. can. The reason why the signal for G light modulation is made to have the opposite polarity from the others is that the light intensity is R:G:B=3:6:1, and considering the polarity of the signal and human vision (R+B). :
This is to ensure that G=(3+1):6=4:6, which is approximately 1:1 and balanced.

Although the liquid crystal panel of this embodiment has been described as being a transmissive liquid crystal panel, the present invention is not limited to this, and it is clear that a reflective type structure may be used. In that case, the pixel electrode may be formed of a metal material.

Although the projection lens system is a Schlieren optical system in (FIG. 5), it is not limited to this; for example, as shown in FIG. , a centrally shielded optical system that projects the scattered light onto a screen may be used.

Further, the structure of the liquid crystal display device of the present invention is TF.
The invention is not limited to T, but is also effective in liquid crystal display devices that use two-terminal elements such as diodes as switching elements.

Furthermore, in the embodiments of the liquid crystal projection type TV of the present invention, the description has been made using the expression as a rear type liquid crystal projection type TV, but the present invention is not limited to this; It goes without saying that a liquid crystal projection type TV may also be used. Further, in the liquid crystal projection television of this embodiment, color separation is performed using a dichroic mirror, but the present invention is not limited to this, and color separation may be performed using, for example, an absorption type color filter.

Furthermore, in the liquid crystal projection television of this embodiment, one projection lens system is provided in each of the R, G, and B light modulation systems, but the invention is not limited to this; for example, mirrors, etc. Needless to say, it is also possible to use a configuration in which the display images modulated by the liquid crystal panel are combined into one image and then projected onto one projection lens system.

Furthermore, although the glass substrate 21 with good mold releasability is used in the embodiment of the present invention, the present invention is not limited to this, and for example, a film with good mold releasability may be used. Films with good mold releasability include silicone resin films, fluororesin films, and olefin resin films such as polyethylene and polypropylene. Further, although the glass substrate 22 is coated with fluororesin, it is not limited to fluororesin, but may be coated with silicone resin or the like, and the substrate is not limited to a glass substrate. Needless to say, a metal substrate may be used instead.

[0053]

As described above, the liquid crystal panel of the present invention has two polymer-dispersed liquid crystal layers, and the average particle diameter of the droplet-like liquid crystal in the two liquid crystal layers or the polymer Since the average pore diameters are different, the scattering properties are good for light having a wide range of wavelengths. For this reason, conventional liquid crystal panels have poor scattering characteristics for light with short or long wavelengths and cannot achieve high contrast, but it is possible to achieve high contrast of 200:1 or more over a wide wavelength range. Conventionally, in order to improve the scattering properties of a polymer-dispersed liquid crystal panel, it was necessary to increase the thickness of the liquid crystal film, which caused the problem that increasing the thickness increased the response time of the liquid crystal.However, in the present invention, the two-layer Because the polymer-dispersed liquid crystal layer is sandwiched between the pixel electrode and the counter electrode, a large voltage is applied to the liquid crystal and the response time is fast, less than 20 milliseconds, despite the overall thickness of the liquid crystal film. has been realized.

Furthermore, the method for manufacturing a liquid crystal panel of the present invention is for manufacturing the liquid crystal panel of the present invention. Even though these devices form two polymer-dispersed liquid crystal layers, it is possible to easily manufacture a liquid crystal panel.

Furthermore, since conventional LCD projection televisions use TN liquid crystals, more than 50% of the light is absorbed, making it impossible to cope with higher brightness or larger screens. Because it uses polymer-dispersed liquid crystal, it can achieve screen brightness more than twice that of conventional LCD projection televisions. Furthermore, polymer-dispersed liquid crystal panels have poor scattering properties, especially in the long wavelength region such as red light, and when a projection television is constructed using the liquid crystal panel, there is a problem of low contrast. By using the panel for red light modulation, the scattering properties are good in all wavelength regions, and the contrast is also 200%.
: 1 or more can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid crystal panel in an embodiment of the first invention.

FIG. 2 is an explanatory diagram of a method for manufacturing a liquid crystal panel in an embodiment of the first invention.

FIG. 3 is a sectional view of a liquid crystal panel in an embodiment of the second invention.

FIG. 4 is an explanatory diagram of a method for manufacturing a liquid crystal panel in an embodiment of the second invention.

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

FIG. 6 is an explanatory diagram of a driving circuit for a liquid crystal panel according to the present invention.

FIG. 7 is an explanatory diagram of a driving circuit for a liquid crystal panel according to the present invention.

FIG. 8 is an explanatory diagram of a center light shielding type projection lens system according to the present invention.

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

FIG. 10 is an equivalent circuit diagram of a liquid crystal panel.

FIG. 11 is a plan view of one pixel portion of the liquid crystal panel.

FIG. 12 is a cross-sectional view of a conventional liquid crystal panel.

FIG. 13 is an explanatory diagram of a conventional method for manufacturing a liquid crystal panel.

FIG. 14 is a configuration diagram of a conventional liquid crystal projection television.

FIG. 15 is an explanatory diagram of a polymer dispersed liquid crystal display device.

[Explanation of symbols]

11 TFT 12 Pixel electrode 14, 31 Counter electrode 15 Polymer dispersed liquid crystal layer 21 Glass substrate 22 Fluororesin 23 Beads 32 Opposite board 41 Sealing resin 54 Polymer dispersed liquid crystal panel 56 Aperture 82 Light shielding body 13 Array board 154 Water droplet liquid crystal 155 Polymer

Claims (10)

[Claims] 1. A polymer-dispersed liquid crystal layer is sandwiched between two upper and lower substrates on which active elements are provided for each pixel electrode, a transparent electrode layer is disposed between the polymer-dispersed liquid crystal layers, and a transparent electrode layer is disposed between the polymer-dispersed liquid crystal layers. A liquid crystal panel comprising a first and a second polymer-dispersed liquid crystal layer. [Claim 2] A first device in which an active element is provided for each pixel electrode.
and a second substrate, and a third substrate having a light transmitting property and having transparent electrodes formed on both sides, and a first polymer-dispersed liquid crystal layer is provided between the first and third substrates; A liquid crystal panel characterized in that a second polymer-dispersed liquid crystal layer is disposed between a second substrate and a third substrate. 3. A polymer-dispersed liquid crystal layer divided into two layers by a transparent electrode layer is used as first and second polymer-dispersed liquid crystal layers, and a polymer and a liquid crystal constituting the first polymer-dispersed liquid crystal layer are used as first and second polymer-dispersed liquid crystal layers. 3. The liquid crystal panel according to claim 1, wherein the material and at least one of a polymer and a liquid crystal material constituting the second polymer-dispersed liquid crystal layer are different from each other. 4. A polymer-dispersed liquid crystal layer divided into two layers by a transparent electrode layer is used as first and second polymer-dispersed liquid crystal layers, and granular liquid crystals formed in the first polymer-dispersed liquid crystal layer are provided. A claim characterized in that the average particle diameter of the droplets or the average void spacing of the polymer surrounding the liquid crystal is different from the average particle diameter of the liquid crystal droplets or the average void spacing of the polymer in the second polymer-dispersed liquid crystal layer. The liquid crystal panel according to claim 1 or claim 2. [Claim 5] A first device in which an active element is provided for each pixel electrode.
After coating a resin containing liquid crystal on the substrate and curing the resin, a transparent electrode is formed on the upper layer of the cured resin, and an active element is provided for each pixel electrode on the transparent electrode. holding the second substrate at a predetermined distance, injecting a resin containing liquid crystal between the transparent electrode and the second substrate, and then irradiating the resin with at least one of light or heat to harden the resin. A method for manufacturing a liquid crystal panel characterized by: [Claim 6] A first device in which an active element is provided for each pixel electrode.
A second substrate having transparent properties and having transparent electrodes formed on both sides is held at a predetermined interval on the substrate, and a third substrate having an active element for each pixel electrode is held on the second substrate at a predetermined distance. After injecting a resin containing liquid crystal between the first substrate and the second substrate and between the second substrate and the third substrate, at least one of light and heat is applied to the resin. A method for manufacturing a liquid crystal panel, which comprises curing a resin by irradiating the resin with water. 7. After applying the resin, the resin is smoothed by stacking a film or a substrate having a release shape on the resin and applying pressure, and then irradiating the resin with at least one of light or heat, 6. The method of manufacturing a liquid crystal panel according to claim 5, wherein the film or substrate is peeled off from the resin after the resin is cured. 8. A first optical element component that separates the light generated by the light generating means into light in a plurality of wavelength ranges; A liquid crystal projection television set comprising: the liquid crystal panel according to claim 1 or 2, which modulates light; and a second optical component which projects the light modulated by the liquid crystal panel. 9. A claim characterized in that the first optical component is a dichroic mirror, and the light generated by the light generating means is separated into light in three regions: blue light, green light, and red light. 8. The liquid crystal projection television set as described in 8. 10. An optical image of a liquid crystal panel that modulates blue light, an optical image of a liquid crystal panel that modulates green light, and an optical image of a liquid crystal panel that modulates red light are arranged at the same position on the screen by optical elements. 9. The liquid crystal projection television set according to claim 8, wherein an image is projected on the television.