JP2946538B2 - Projection type active matrix liquid crystal display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a projection type active matrix liquid crystal display device.

[Prior Art] In recent years, liquid crystal displays have been utilizing personal word processors,
Widely used in handheld computers, pocket TVs, etc. Among them, an active matrix liquid crystal display element in which an active element is arranged for each pixel electrode has attracted attention and is being actively developed.

Initially, a liquid crystal display device using DS-mode (dynamic scattering) liquid crystal was proposed for such a liquid crystal display device.
The DS mode has a drawback that the current flowing through the liquid crystal is high, so that the current consumption is large. Currently, a liquid crystal display using a TN (twisted nematic) type liquid crystal is mainstream and appears in the market as a pocket TV. The TN mode type liquid crystal has a very small leakage current and low power consumption, and thus is suitable for a battery-powered application.

[Problems to be Solved by the Invention] When an active matrix liquid crystal display element is used in the DS mode, the leakage current of the liquid crystal itself is large. For this reason, there is a problem that a large storage capacitor must be provided in parallel with each pixel, and the power consumption of the liquid crystal display element itself increases.

In the TN mode, since the leakage current of the liquid crystal itself is extremely small, it is not necessary to add a large storage capacity, and the power consumption of the liquid crystal display element itself can be reduced. But TN
Since the mode requires two polarizing plates, there is a problem that the light transmittance is small.

In particular, when projecting an image, an extremely strong light source is required, and it is difficult to obtain high contrast on a projection screen, and there is a problem that the heat generated by the light source affects a liquid crystal display element.

In order to solve the problem of the TN mode, a mode using a scattering-transmission characteristic of a liquid crystal resin composite in which a nematic liquid crystal is dispersed and held in a resin matrix has been proposed.

However, there have been problems that a sufficient luminance and contrast ratio cannot be obtained at a low voltage, and that it is difficult to balance colors.

[Means for Solving the Problems] The present invention has been made in order to solve the above-mentioned problems.
A projection type active matrix liquid crystal display device having a plurality of color light sources, a plurality of active matrix liquid crystal display elements on which light from each color light source is incident, and a projection optical system for combining and projecting light emitted from the active matrix liquid crystal display elements A liquid crystal resin in which nematic liquid crystal having a positive dielectric anisotropy is dispersed and held in a resin matrix between an active matrix substrate provided with an active element for each pixel electrode and a counter electrode substrate provided with a counter electrode. A complex is provided,
The refractive index of the resin matrix is made to substantially match the ordinary refractive index (n _o ) of the liquid crystal to be used. The liquid crystal to be used has a refractive index anisotropy Δn of 0.18 or more, and each color dispersed and held in the resin matrix. the average particle diameter R _X crystal of ([mu] m), both electrode gap d _X (μm), the dominant wavelength lambda _X color of each light source has an average particle of the liquid crystal in the case where the main wavelength lambda _{G =} 540 nm of the green light source For the diameter R _G (μm) and the gap d _G (μm) between both electrodes, And a projection type active matrix liquid crystal display device characterized by satisfying the following relationship:

Further, a light source of three colors of RGB and three active matrix liquid crystal display elements are provided, and the average particle diameters R _R , R _G , R _B of the liquid crystal of the three color liquid crystal display elements, the gaps d _R , d _G between the two electrodes, d _B , the main wavelengths λ _R , λ _G , λ _B of the colors of each light source are The above-mentioned projection type active matrix liquid crystal display device which satisfies the above relationship is provided.

The resin used in the liquid crystal resin composite is a photocurable vinyl resin, and a liquid crystal resin composite obtained by curing the resin by irradiating light to a solution in which liquid crystal and the resin are uniformly dissolved is used. And a projection type active matrix liquid crystal display device.

Further, the present invention provides the above-mentioned projection type active matrix liquid crystal display device, which is provided with a liquid crystal resin composite in which liquid bubbles of individual liquid crystals communicate with each other via a gap.

In the present invention, as a liquid crystal material sandwiched between the active matrix substrate and the counter electrode substrate, a liquid crystal resin composite capable of electrically controlling a scattering state and a transmission state is used.
Since the active matrix liquid crystal display element sandwiching the liquid crystal resin composite is used, no polarizing plate is required, and the light transmittance at the time of transmission can be greatly improved. Further, the average particle diameter R _X (μm) in the liquid crystal resin composite and the gap d _X (μ
Since m) is set for each color, when the colors are mixed in the projection display, a display with good color balance, brightness, and good contrast ratio can be obtained.

In addition, since problems such as alignment treatment indispensable for the TN type liquid crystal display element and destruction of the active element due to generated static electricity can be avoided, the production yield of the liquid crystal display element can be greatly improved.

Further, since the liquid crystal resin composite is in the form of a film after curing, problems such as short-circuit between the substrates due to pressurization of the substrates and destruction of the active element due to the movement of the spacer are less likely to occur.

In addition, this liquid crystal resin composite has the same specific resistance as that of the conventional TN mode, and does not require a large storage capacitor for each pixel electrode as in the DS mode. In addition, the power consumption of the liquid crystal display element can be kept low. Therefore, the production can be facilitated because the production can be performed only by removing the alignment film forming step from the conventional TN mode liquid crystal display element production process.

The specific resistance of the liquid crystal resin composite is preferably 5 × 10 ⁹ Ωcm or more. Furthermore, in order to minimize the voltage drop due to leakage current or the like, it is more preferably 10 ¹⁰ Ωcm or more,
In this case, it is not necessary to provide a large storage capacitance for each pixel electrode.

Examples of the active element provided on the pixel electrode include a transistor, a diode, and a non-linear resistance element. Two or more active elements may be arranged in one pixel as needed. A liquid crystal display element is obtained by sandwiching the liquid crystal resin composite between an active matrix substrate provided with such an active element and a pixel electrode connected thereto and a counter electrode substrate provided with a counter electrode.

The projection type active matrix liquid crystal display device of the present invention uses a plurality of color light sources and a projection optical system. Conventionally known projection light sources and projection optical systems such as lenses can be used as the color light source and the projection optical system. Usually, the plurality of liquid crystal display elements are arranged corresponding to each color light source, and an image is synthesized by the arrangement. What is necessary is just to make it project.

As this color light source, a dedicated light source may be used for each color, or the light of one light source may be used by splitting. The light emitted from this color light source is made incident on an active matrix liquid crystal display device. In the present invention, the plurality of active matrix liquid crystal display elements are used in accordance with the characteristics of each light source color. Light emitted from these active matrix liquid crystal display elements is mixed and projected. As a result, a bright, well-balanced and high-contrast projected image can be obtained.

In the present invention, the liquid crystal resin composite is composed of a resin matrix in which a large number of fine holes are formed and a nematic liquid crystal having a positive dielectric anisotropy filled in the holes, and the refractive index of the resin matrix is used. ordinary refractive index of the liquid crystals (n _o)
And a liquid crystal resin composite having a liquid crystal having a refractive index anisotropy Δn of 0.18 or more is used. This liquid crystal resin composite is sandwiched between an active matrix substrate and a counter electrode substrate to form a liquid crystal display element. Depending on the state of voltage application between the electrodes of the liquid crystal display element, the refractive index of the liquid crystal changes, and the relationship between the refractive index of the resin matrix and the refractive index of the liquid crystal changes. State, and when the refractive index is different, the state is a scattering state.

The liquid crystal resin composite composed of the resin matrix in which a large number of fine holes are formed and the liquid crystal filled in the holes has a structure in which the liquid crystal is sealed in a liquid bubble such as a microcapsule. The individual microcapsules do not have to be completely independent, and liquid bubbles of individual liquid crystals may be communicated via the slits like a porous body.

The liquid crystal resin composite used for the liquid crystal display element in the present invention is prepared by mixing a nematic liquid crystal and a material constituting a resin matrix into a solution or a latex, and then curing the mixture by photocuring, heat curing, and solvent removal. The resin matrix may be separated by curing, reaction curing, or the like, so that the nematic liquid crystal is dispersed in the resin matrix.

It is preferable to use a photo-curing or heat-curing resin, because the resin can be cured in a closed system.

In particular, the use of a photo-curing type resin is preferable because it can be cured in a short time without being affected by heat.

As a specific manufacturing method, cells were formed using a sealing material in the same manner as a conventional ordinary nematic liquid crystal, a mixture of an uncured nematic liquid crystal and a resin matrix was injected from an injection port, and the injection port was sealed. Thereafter, curing may be performed by irradiating light or heating.

In the case of the liquid crystal display element of the present invention, without using a sealing material, for example, a mixture of an uncured nematic liquid crystal and a resin matrix is supplied on a substrate provided with a transparent electrode as a counter electrode, and thereafter, An active matrix substrate provided with an active element for each pixel electrode may be stacked and cured by light irradiation or the like.

Of course, after that, a sealing material may be applied to the periphery to seal the periphery. According to this manufacturing method, the mixture of the uncured nematic liquid crystal and the resin matrix may be simply supplied by roll coating, spin coating, printing, coating with a dispenser, or the like, so that the injection step is simple and the productivity is extremely high. Good.

In addition, the mixture of the uncured nematic liquid crystal and the resin matrix may have ceramic particles for controlling the substrate gap, plastic particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers, and other adverse effects on the performance of the present invention. May be added.

By curing this element in a state where a sufficiently high voltage is applied only to a specific part during the curing step, the part can be always in a light transmitting state, so if there is something to be fixedly displayed, May form such a normally transparent portion.

The response time of a liquid crystal display device using such a liquid crystal resin composite is such that the rise of voltage application is about 3 to 50 msec and the fall of voltage removal is about 10 to 80 msec.
Faster than liquid crystal display element in mode.

Further, the electro-optical characteristics of the voltage-transmittance are the same as those of the conventional TN.
Compared to the liquid crystal display element in the mode, the mode is relatively gentle, and driving for gradation display is easy.

The transmittance of the liquid crystal display device using the liquid crystal resin composite in the transmission state is preferably as high as possible, and the haze value in the scattering state is preferably 80% or more.

In the present invention, in a state in which the voltage is applied, the refractive index of the resin matrix (after curing) is to match the ordinary refractive index of the liquid crystal used (n _o).

Accordingly, light is transmitted when the refractive index of the resin matrix and the refractive index of the liquid crystal match, and the light is scattered (white turbid) when they do not match. The scattering properties of this element
A display having a higher contrast ratio and higher than that of the liquid crystal display element of the DS mode can be obtained.

An object of the present invention is to provide an optimal configuration of a projection type active matrix liquid crystal display device using an active matrix liquid crystal display element sandwiching the liquid crystal resin composite.

That is, an object of the present invention is to provide a projection type active matrix liquid crystal display device which has a high transmittance at the time of transmission and a high scattering property (light shielding property) at the time of scattering, has a good color balance, and has a large contrast ratio.

The factors for determining the electro-optical characteristic of the active matrix liquid crystal display device using the liquid crystal polymer composite material, the refractive index of the liquid crystal used (ordinary refractive index n _o, the extraordinary refractive index n _e),
Relative permittivity (ε, ε⊥, and ⊥ indicate parallel and perpendicular to the liquid crystal molecular axis, respectively), viscosity, elastic constant, and refractive index n _p , relative permittivity ε _p , elastic modulus, and resin of the resin used. The average particle diameter R of the liquid crystal dispersed and held in the matrix, the volume fraction Φ, the electrode substrate gap between both electrodes (thickness of the liquid crystal resin composite) d, the maximum applied to the liquid crystal resin composite in the pixel portion by the active element Effective applied voltage V and the like. Here, the average particle diameter R of the liquid crystal indicates the diameter when the liquid crystal forms a substantially spherical liquid bubble, and when the liquid crystal has a porous communication structure, the directors of the liquid crystal have a correlation with each other. Means the diameter of the area.

The electro-optical characteristics of the active matrix liquid crystal display device using the liquid crystal resin composite according to the present invention include a high scattering property in the absence of an electric field and a high transmissivity in the application of an electric field, that is, a high display contrast ratio. It is desirable to have. When projection display is performed using such a liquid crystal display element, a display with high luminance and a high contrast ratio can be obtained.

In order to obtain such a display, it is necessary that the above factors have an optimal relationship.

Particularly important factor that determines the electro-optical characteristic of the active matrix liquid crystal display element among these factors are the refractive index of the liquid crystal used (refractive index anisotropy [Delta] n = extraordinary refractive index n _e -
The ordinary light refractive index n _o ), the average particle diameter R of the liquid crystal, and the gap d between the two electrode substrates. The average particle diameter R _X of the liquid crystal for each liquid crystal display element, the gap between the electrode substrates according to the main wavelength λ _X of the color light source. d Define _X and optimize.

Liquid crystal refractive index anisotropy Δn of using (= n _e -n _o) contributes to scattering at the time of no electric field, to obtain a high scattering property, preferably more than a certain large, specifically Δ
n> 0.18 is a preferable condition. Further, the ordinary refractive index n _o of the liquid crystal used is preferably substantially matches the refractive index n _p of the resin matrix, high transparency is obtained during this time an electric field is applied. Specifically, it is preferable to satisfy the relationship of _{n o -0.03 <n p <n} o +0.05.

The average particle size R of the liquid crystal dispersed and held in the resin matrix is a very important factor, and contributes to the scattering property in the absence of an electric field and the operation characteristics of the liquid crystal in the presence of an electric field. The scattering property in the absence of an electric field varies depending on the relationship between the refractive index anisotropy Δn of the liquid crystal used, the wavelength λ of light, and the average particle diameter R of the liquid crystal. Therefore, depending on the dominant wavelength lambda _X of each light source, for maximum scattering per unit operation amount of the liquid crystal, each crystal display average particle size of the liquid crystal for each element R _X, both electrodes substrate gap d _X It is necessary to set as follows.

When the main wavelength of the green light source is λ _G = 540 nm, the average particle diameter of the liquid crystal is R _G (μm), and the gap between the electrode substrates is d _G.

_{0.3 <R G · Δn <0.7} (1) 4R G <d G <8R G (2) In particular, since the color of the light source is a _{green, 0.4 <R G · Δn <} 0.6
When Δn is about 0.25, R _G is 2.
It becomes about 0 μm. Further, it is preferable that Δn is 0.2 or more in order to obtain strong scattering.

When the average particle diameter _RG of the liquid crystal display element with respect to the green light source is smaller than the range of the expression (1), the scattering property has a wavelength dependence that the shorter wavelength side is stronger, and the operation of the liquid crystal is increased. Since a higher electric field is required, power consumption increases. On the other hand, when the average particle size R _G is larger than the range of the formula (1), the scattering property is small over the entire visible light range, the scattering ratio is weak, the contrast ratio is reduced, and the light scattering property is low. Another problem is that the response to scattering is slow. Therefore, the above range is set.

The electrode substrate gap d _G of the liquid crystal display element for a green light source is also an important factor. When d _G is increased, the scattering property in the absence of an electric field is improved. However, if d _G is too large, and requires a high voltage in order to achieve sufficient transparency when an electric field is applied, increase in the power consumption, the active element for a conventional TN, drive
There is a problem that the IC cannot be used. Also, reducing the d _G, but high transparency at a low voltage is obtained, the scattering property at the time of no electric field decreases. Therefore, in order to achieve both the scattering property when no electric field is applied and the high transparency when applying an electric field, d
_G (μm) is set so as to satisfy the above equation (2).

Further, in order to make the characteristics of each color uniform, R _X / λ _X is almost equal to R _G / λ _G in all liquid crystal display elements, and d _X / λ _X is d _G / λ _X.
It is almost equal to λ _G, and is as follows.

The equation (3) is for optimizing the scattering property of the liquid crystal, and for making the phase shift of the liquid crystal substantially equal for each color.

The expression (4) is used to make the relationship between the applied voltage and the scattering property and the voltage-transmittance characteristic match for each color under the expression (3).

Therefore, by simultaneously satisfying these conditions, it is possible to obtain a projection-type liquid crystal display device having a high luminance, a high contrast ratio, and a good voltage balance with a uniform voltage-transmittance characteristic.

In particular, R _X / λ _X and d _X / λ of a plurality of liquid crystal display elements, respectively.
And _X, the optimum when to match the respective R _G / λ _G and d _G / _{λ G.}

For this reason, when light sources of three colors of RGB (red, green, blue) are used, R _X / λ _X and d _X / λ _X of the three liquid crystal display elements are respectively replaced by R _G / λ _G and d. _G / λ _G is almost the same. Specifically, the following is performed.

The absolute value of the electrode substrate gap d _X, depending on the applied voltage to be used, the display luminance may be selected so that the contrast ratio is optimal. When a rectangular wave at 0 to V _MAX is applied, the effective applied voltage is the same as the applied voltage.

0.5R _G · V _MAX <d _G <R _G · V _MAX (7) In particular, it is preferable to be 0.8R _G · V _MAX or less. TF like a normal TN type active matrix liquid crystal display
When T is used, the effective applied voltage is preferably set to 10 V or less. For example, when V _MAX = 8 V, d _G is approximately 8 to
It may be about 13 μm.

The liquid crystal used must have a refractive index anisotropy Δn of 0.18 or more. Among them, 0.20 or more is preferable,
In particular, it is preferably 0.23 or more. Further, the dielectric anisotropy Δε (= εε−ε) is preferably set to 10 or more, particularly preferably 13 or more.

The color balance by a plurality of liquid crystal display elements can be improved to some extent by modulating the drive signal, but when there is no electric field, the balance of the characteristics on the low voltage side by gradation display is as follows.
It is difficult to improve only by modulating the drive signal.

One major advantage of the present invention is that the voltage-transmittance characteristics for each color are aligned without strongly depending on the modulation of the drive signal.
That is, a display with a well-balanced color can be obtained.

As described above, a plurality of active matrix liquid crystal display elements using a liquid crystal resin composite which are in a transparent state when a voltage is applied and in a scattering state when no electric field is used, and each liquid crystal display element is described above corresponding to each color light source ( Equation 1), Equation (2),
By satisfying all of the conditions of the equations (3) and (4), the conventional active element and driving IC for TN can be used.
Bright display with good color balance and high contrast ratio is possible. More specifically, a display with a contrast ratio of 100 or more and a transmittance of 70% or more when an electric field is applied becomes possible. Further, since the dynamic range is wide, an excellent element capable of displaying fine halftones can be obtained.

Further, in order to improve the scattering property in the absence of an electric field, it is effective to increase the volume fraction Φ of the operable liquid crystal in the liquid crystal resin composite, and Φ> 20% is preferable. To have Φ> 35% is preferred. On the other hand, if Φ is too large, the structural stability of the liquid crystal resin composite deteriorates, so Φ <70% is preferable.

When no electric field is applied, the liquid crystal display element according to the present invention exhibits a scattering state (that is, a cloudy state) due to a difference in refractive index between a liquid crystal that is not aligned and a resin matrix. For this reason, when used as a projection display device as in the present invention, light is scattered in portions without electrodes, and light does not reach the screen without providing a light-shielding film in portions other than the pixel portion, Looks black. Accordingly, in order to prevent light leakage from portions other than the pixel electrodes, it is not necessary to shield portions other than the pixel electrodes with a light-shielding film or the like, which also has an advantage that a step of forming a light-shielding film is not required. Have.

An electric field is applied to a desired pixel of the liquid crystal display device. In the pixel portion to which the electric field is applied, the liquid crystal is aligned, and the ordinary light refractive index (n _o ) of the liquid crystal matches the refractive index (n _p ) of the resin matrix to indicate a transmissive state. Light is transmitted, and the image is displayed brightly on the screen.

By curing this element in a state where a sufficiently high voltage is applied only to a specific portion during the curing step,
Since the portion can always be in a light transmitting state, if there is something to be fixedly displayed, such a normally transmitting portion may be formed.

Further, a dye, a pigment, and the like may be mixed in the liquid crystal resin composite.

FIG. 1 is a schematic diagram of an example using a dichroic prism of a projection type active matrix liquid crystal display device of the present invention.

In FIG. 1, 1 is a light source, 2 is a concave mirror, 3 is a condenser lens, 4 is a dichroic prism for spectrum, 5
A, 5B, 5C, and 5D are mirrors, and constitute a color light source with 1 to 5D. 6A, 6B, 6C are active matrix liquid crystal display elements sandwiching a liquid crystal resin composite corresponding to each color, 7 is a dichroic prism for synthesis, 8 is a projection lens, 9 is an aperture for removing light other than straight light, and 10 is projection Screen. 7 to 9 constitute a projection optical system.

FIG. 2 is a schematic view of an example of the projection type active matrix liquid crystal display device of the present invention in which a dichroic prism is not used.

In FIG. 2, 11 is a light source, 12 is a concave mirror, 13 is a condenser lens, 15A, 15B and 15C are dichroic mirrors, and 11 to 15C constitute a color light source. 16A, 16B, 16C are active matrix liquid crystal display elements sandwiching a liquid crystal resin composite corresponding to each color, 18A, 18B, 18C are projection lenses provided for each color, 19A, 19B, 19C are provided for each color An aperture for removing light other than straight light, 20 is a projection screen. The projection optical system is composed of 18A to 19C.

FIG. 3 is a sectional view of an active matrix liquid crystal display element used in the projection type active matrix liquid crystal display device of the present invention.

In FIG. 3, reference numeral 21 denotes an active matrix liquid crystal display element; 22, a substrate made of glass or plastic for an active matrix substrate; 23, a pixel electrode such as ITO (In ₂ O ₃ —SnO ₂ ) and SnO _2; , A diode, a non-linear resistance element, etc., 25 is a glass or plastic substrate for a counter electrode substrate, 26 is a counter electrode such as ITO or SnO ₂ and 27 is a liquid crystal resin composite sandwiched between both substrates. Is shown.

When a three-terminal element such as a TFT (thin film transistor) is used as an active element in the present invention, the counter electrode substrate may be provided with a solid electrode common to all pixels, but when a two-terminal element such as a MIM element or a PIN diode is used. In this method, the counter electrode substrate is patterned in a stripe shape.

When a TFT is used as an active element, silicon is suitable as a semiconductor material. In particular, polycrystalline silicon is preferable because it does not have photosensitivity like amorphous silicon and does not malfunction even if light from a light source is not blocked by a light-blocking film. When this polycrystalline silicon is used as a projection type liquid crystal display device as in the present invention, a strong projection light source can be used, and a bright display can be obtained.

In the case of a conventional TN-type liquid crystal display device, a light-shielding film is often formed between pixels in order to suppress light leakage from between the pixels. The formation of the light-shielding film in the active element portion does not significantly affect the entire process. That is, even if polycrystalline silicon is used as an active element and a light-shielding film is not formed in an active element portion, the number of steps cannot be reduced if a light-shielding film needs to be formed between pixels.

In contrast, in the present invention, as described above, due to the use of liquid crystal ordinary refractive index (n _o) and liquid crystal polymer composite material which is adapted substantially to match that used by the refractive index of the resin matrix, an electric field Light is scattered in a portion where no is applied, and becomes black on the projected screen. Therefore, a light-shielding film need not be formed between pixels. When polycrystalline silicon is used as an active element, a light-shielding film does not need to be formed in the active element part, so that a step of forming a light-shielding film can be eliminated, and productivity is improved by reducing the number of steps. .

The electrode is usually a transparent electrode, but when used as a reflective liquid crystal display device, it may be a reflective electrode of chromium, aluminum, or the like.

When the projection type active matrix liquid crystal display device of the present invention is used in a reflection type, a high contrast ratio can be obtained in the same electrode substrate gap as compared with a case in which the projection type active matrix liquid crystal display device is used in a transmission type. Therefore, when it is sufficient to obtain the same contrast ratio as that of the transmission type, the gap between the electrode substrates can be made slightly smaller within the range of the present invention, and the driving voltage can be reduced.

The liquid crystal display device according to the present invention may further include an infrared cut filter, an ultraviolet cut filter, or the like, may print characters, figures, or the like, or may use a plurality of liquid crystal display elements. You may.

Further, in the present invention, a protective plate such as a glass plate or a plastic plate may be laminated outside the liquid crystal display element. Thereby, even if the surface is pressurized, the risk of breakage is reduced, and safety is improved.

In the present invention, when a photocurable resin is used as the uncured resin constituting the liquid crystal resin composite, use of a photocurable vinyl resin is preferred.

Specifically, a photocurable acrylic resin is exemplified, and a resin containing an acrylic oligomer which is polymerized and cured by light irradiation is particularly preferable.

The liquid crystal used in the present invention is a nematic liquid crystal having a positive dielectric anisotropy, a liquid crystal in which the refractive index of a resin matrix matches the ordinary light refractive index (n _o ) of the liquid crystal. The composition may be used, but it is more advantageous to use the composition in order to satisfy various required performances such as an operating temperature range and an operating voltage.

When a photocurable resin is used, the liquid crystal used in the liquid crystal resin composite preferably dissolves the photocurable resin uniformly, and the cured product after light exposure does not dissolve or is difficult to dissolve. When a composition is used, it is desirable that the solubility of each liquid crystal be as close as possible.

When manufacturing a liquid crystal resin composite, an active matrix substrate and a counter electrode substrate are arranged so that the electrode surfaces face each other as in a conventional ordinary liquid crystal display element, the periphery is sealed with a sealing material, and an injection port is formed. A liquid mixture for an uncured liquid crystal resin composite may be injected from above to seal the injection port, or a mixture of a curable compound and liquid crystal may be supplied on a substrate, and the opposing substrates may be overlapped. May be manufactured.

The liquid crystal display element of the present invention may be a liquid crystal in which a dichroic dye, a simple dye, or a pigment is added, or a liquid crystal that is colored as a curable compound may be used.

In the present invention, the liquid crystal is used as a solvent at the time of forming the liquid crystal resin composite, and the photocurable resin is cured by light exposure, so that it is not necessary to evaporate a mere solvent or water which is unnecessary at the time of curing. Therefore, since it can be cured in a closed system, the conventional manufacturing method of injecting into a cell can be adopted as it is, and it has high reliability and also has an effect of bonding two substrates with a photocurable resin, so that more reliability is obtained. Will be higher.

By using the liquid crystal resin composite in this way, the risk of short circuit between the upper and lower transparent electrodes is low, and there is no need to strictly control the orientation and the substrate gap as in a normal TN type display element, so that transmission is possible. A liquid crystal display element capable of controlling the state and the scattering state can be manufactured with extremely high productivity.

In this liquid crystal display element, when the substrate is made of plastic or thin glass, a protective plate made of plastic, glass, or the like is preferably laminated on the outside for further protection.

When applying a voltage for driving, the liquid crystal display device of the present invention is driven such that an applied voltage equal to or less than the maximum effective voltage of the above-described formula (7) is applied to the liquid crystal resin composite between the electrodes of the pixel. Just do it.

In the present invention, the color light source, the projection optical system, the projection screen to be projected, and the like can use a conventional light source, projection optical system, and projection screen, and the active matrix liquid crystal display of the present invention is provided between the color light source and the projection optical system. The elements may be arranged. In this case, the projection optical system may combine the images of a plurality of active matrix liquid crystal display elements using the optical system as shown in FIG. 1 and then project the images, or as shown in FIG. The images of the matrix liquid crystal display elements may be individually projected onto a projection screen and synthesized on the projection screen.

Further, in the above-described example, the color light source is also used by dispersing light from one light source. However, a plurality of color light sources may be separately provided in advance to be incident on the active matrix liquid crystal display element.

Light sources used for these color light sources include a halogen lamp, a metal halide lamp, a xenon lamp, and the like, and the light use efficiency can be increased by combining a concave mirror, a condenser lens, and the like.

Further, a cooling system may be added thereto, an infrared cut filter or an ultraviolet cut filter may be used in combination, or a channel display such as an LED may be added.

In particular, in the case of this projection type display, a device for reducing the diffused light on the optical path, for example, 9, 19A, 19 in FIGS.
By providing apertures and spots as shown in B and 19C, the display contrast can be increased.

That is, as a device for reducing diffused light, of light that has passed through a liquid crystal display element, light that goes straight to incident light (light that passes through a portion where a pixel portion is in a transmission state) is extracted, and light that does not go straight (liquid crystal resin composite). Light scattered in the part where the body is in the scattering state)
It is preferable to use a material that reduces the contrast in order to improve the contrast ratio. In particular, it is preferable that the light that goes straight does not decrease and the light that does not go straight reduces the diffused light.

The device for reducing the diffused light may be provided between the projection optical system and the projection screen as shown in FIGS. 1 and 2, or the projection optical system may include a plurality of projection optical systems. When it is composed of lenses, it may be arranged between the lenses.

The device for reducing the diffused light is not limited to the aperture and the spot as described above, and may be, for example, a small-area mirror arranged on the optical path.

The ratio between the linear component and the scattering component reaching the projection screen can be controlled by the diameter of a spot, a mirror or the like and the focal length of a lens, and may be set so as to obtain desired display contrast and display luminance.

The projection type active matrix liquid crystal display device of the present invention may be used in a front projection type or a rear projection type.

[Operation] According to the present invention, it is possible to obtain a projection display having a good color balance, a high display luminance, and a high contrast ratio.

Particularly, in the present invention, since the active matrix liquid crystal display element sandwiching the liquid crystal resin composite having specific characteristics corresponding to the color of the light source as described above is used, the balance of each color is good, and a special correction is required for the driving circuit. Conventional TN technology enables beautiful gradation display of colors without incorporating a circuit, and the applied maximum effective applied voltage can be reduced to 10 V or less.
Active devices and driving ICs used for the active matrix liquid crystal display device of the type can be easily used.

[Example] Example 1 Chromium was placed on a glass substrate (Corning 7059 substrate).
60 nm was deposited and patterned to form a gate electrode. Subsequently, a silicon oxynitride film and an amorphous silicon film were deposited by a plasma CVD apparatus. This was annealed using a laser and then patterned to obtain polycrystalline silicon. Then, phosphorus-doped amorphous silicon and chromium were deposited using plasma CVD and a vapor deposition apparatus, respectively, and were patterned so as to cover the polycrystalline silicon, thereby forming a first layer source electrode and drain electrode. Further, after depositing ITO, patterning was performed to form a pixel electrode. Subsequently, chromium and aluminum were successively vapor-deposited and patterned so as to connect the pixel electrode with the first-layer source electrode and drain electrode, thereby forming a second-layer source electrode and drain electrode. Thereafter, a silicon oxynitride film was deposited again by a plasma CVD apparatus to serve as a protective film, thereby forming an active matrix substrate.

A counter electrode substrate made of the same glass substrate with a solid ITO electrode formed on the entire surface and an active matrix substrate manufactured earlier are placed so that the electrode surfaces face each other, and a spacer with a diameter of about 11.0 μm is scattered inside. except inlet section and its vicinity, and sealed with a sealant of epoxy, substrate gap d _G was prepared empty cell of approximately 11.0 .mu.m.

6 parts of 2-ethylhexyl acrylate, 18 parts of hydroxyethyl acrylate, 20 parts of an acrylic oligomer ("M-1200" manufactured by Toa Gosei Chemical Co., Ltd.), 0.4 parts of "Darocur 1116" manufactured by Merck as a photocuring initiator, and liquid crystal B
62 parts of "E-8" manufactured by DH were uniformly dissolved.

This mixture was injected into the empty cell manufactured by the above method from the inlet, and the inlet was sealed. This was irradiated with ultraviolet rays for 60 seconds to cure the liquid crystal resin composite, thereby producing an active matrix liquid crystal display element for green display.

The average particle diameter _RG of the liquid crystal in the liquid crystal resin composite of the liquid crystal display element thus prepared is about 1.9 μm, and the refractive index anisotropy Δn of the liquid crystal.
Was about 0.24 and the dielectric anisotropy Δε was about 15.6.

Similarly, an active matrix liquid crystal display element for red display was produced. The average particle size R _R of this liquid crystal is about 2.4μ
m, the substrate gap d _R was about 12.5 .mu.m.

Similarly, an active matrix liquid crystal display element for blue display was produced. The average particle size R _B of this liquid crystal is about 1.5μ
m, the substrate gap d _B was about 9.0 .mu.m.

The wavelength characteristics of the transmittance T _OFF of these liquid crystal display elements in the absence of an electric field are as shown in FIG.
570 to 670 nm, green (G) 490 to 580 nm, and blue (B) around 420 to 520 nm, showing high scattering, that is, low T _OFF .

Using these three liquid crystal display elements, a projection type display device is configured with the configuration shown in FIG. 1, a video signal is input to a drive circuit, and the voltage applied to the liquid crystal resin composite is 8 V in effective value. And a projection image was projected on a projection screen.

As a result, an image of a moving image display without a full-color afterimage is obtained, the display is almost balanced in each gradation, and the contrast ratio on the projection screen is 10%.
A bright display of 0 or more was obtained.

The contrast ratio of the image projected on the projection screen was about 60 when the aperture as a device for reducing diffused light was not used.

Comparative Example 1 Three liquid crystal display elements for green of Example 1 were prepared, and they were combined with a three-color light source of RGB to construct a projection display device similar to that of Example 1.

The display obtained by this projection type display device was a reddish image as a whole, and the tendency was particularly remarkable in halftone display. When no electric field was applied to any of the three liquid crystal display elements, the projection screen turned dark red instead of black. This is thought to be due to the difference in the threshold voltage characteristics of the liquid crystal depending on the RGB.
Investigation of the applied voltage-transmittance characteristics for each B revealed that in the halftone region, at the same applied voltage, R had the highest transmittance and B had the lowest.

Substrate gap d _R of the Comparative Example 2 three liquid crystal display elements, d _G, carrying out the d _B Example 1
In the same manner as described above, only the average particle diameters R _R , R _G , and R _{B of} the liquid crystal were about 3.6 μm for red, about 2.9 μm for green, and about 2.3 μm for blue. These were combined with RGB three-color light sources to construct a projection display device similar to that of Example 1.

The display obtained by this projection display device was bright, but only a display having a low contrast ratio of about 10 was obtained.

Example 2 Using the same liquid crystal display element as in Example 1, a projection type display device having the configuration shown in FIG. 2 was formed. This projection type display device also had a good color balance similar to that of Example 1, and a bright display having a high contrast ratio was obtained.

[Effect of the Invention] In the projection type active matrix liquid crystal display device of the present invention, the liquid crystal material sandwiched between the active matrix substrate and the counter electrode substrate is a liquid crystal resin capable of electrically controlling a scattering state and a transmission state. Since the liquid crystal display element sandwiching the composite is used, a polarizing plate is not required, the light transmittance at the time of transmission can be greatly improved, and a bright projected image can be obtained.

The liquid crystal display device of the present invention has a high scattering property in a state where no electric field is applied, and has a high transmittance in a state where an electric field is applied by an active element. Even in driving using an IC, a display having a high contrast ratio and high luminance can be performed.

Further, in the present invention, since the characteristics of the liquid crystal display element are optimized for each color of the color light source, a display with good color balance can be obtained even in a halftone.

In addition, since it is not necessary to use a polarizing plate, there is an advantage that the wavelength dependence of optical characteristics is small, and color correction of a light source becomes almost unnecessary.

Further, the problem of alignment treatment such as rubbing, which is indispensable for a TN type liquid crystal display element, and the problem of destruction of an active element due to generation of static electricity accompanying the rubbing can be avoided, so that the production yield of the liquid crystal display element can be greatly improved.

Further, since the liquid crystal resin composite is in the form of a film after curing, problems such as short-circuit between the substrates due to pressurization of the substrates and destruction of the active element due to the movement of the spacer are less likely to occur.

In addition, this liquid crystal resin composite has the same specific resistance as that of the conventional TN mode, and does not require a large storage capacitor for each pixel electrode as in the conventional DS mode, making it easy to design active elements. Thus, the ratio of the effective pixel electrode area can be easily increased, and the power consumption of the liquid crystal display element can be kept low.

Further, since the manufacturing process of the conventional TN mode liquid crystal display element can be performed only by removing the alignment film forming step, the production is easy.

In addition, a liquid crystal display device using this liquid crystal resin composite
It also has the feature that the response time is short, and it is easy to display moving images. Further, the electro-optical characteristics (voltage-transmittance) of the liquid crystal display element are relatively gentle compared to the TN mode liquid crystal display element, and therefore, the liquid crystal display element can be easily applied to gradation display.

Further, in the liquid crystal display element according to the present invention, light is scattered in a portion to which no electric field is applied. No need to shade. Therefore, in particular, by using an active element made of polycrystalline silicon as the active element, a high-brightness projection light source can be used without a light-shielding film in the active element portion, and a high-brightness projection type liquid crystal display device can be easily manufactured. Obtainable. Further, in this case, no light-shielding film needs to be provided, and the production process can be further simplified.

In addition, the present invention can be applied to various applications within a range that does not impair the effects of the present invention.

[Brief description of the drawings]

1 and 2 are schematic views showing the configuration of a basic example of a projection type active matrix liquid crystal display device of the present invention. FIG. 3 is a sectional view showing a basic configuration of an active matrix liquid crystal display element used in the present invention. FIG. 4 shows the transmittance of the liquid crystal display device of Example 1 in the absence of an electric field.
FIG. 4 is a diagram showing wavelength characteristics of T _OFF . Note that R indicates red, G indicates green, and B indicates blue. Light source: 1,11 Concave mirror: 2, 12 Condenser lens: 3, 13 Dichroic prism for spectrum: 4 Mirror: 5A, 5B, 5C, 5D Active matrix liquid crystal display device: 6A, 6B, 6C, 16A,
16B, 16C, 21 Dichroic prism for synthesis: 7 Projection lens: 8, 18A, 18B, 18C Aperture: 9, 19A, 19B, 19C Projection screen: 10, 20 Dichroic mirror: 15A, 15B, 15C Substrate: 22, 25 pixels Electrodes: 23 Active elements: 24 Counter electrodes: 26 Liquid crystal resin composite: 27

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1333

Claims (4)

(57) [Claims] 1. A projection type comprising: a plurality of color light sources; a plurality of active matrix liquid crystal display elements on which light from each color light source is incident; and a projection optical system for combining and projecting light emitted from the active matrix liquid crystal display elements. In an active matrix liquid crystal display device, a nematic liquid crystal having a positive dielectric anisotropy is dispersed in a resin matrix between an active matrix substrate provided with an active element for each pixel electrode and a counter electrode substrate provided with a counter electrode. The held liquid crystal resin composite is provided so that the refractive index of the resin matrix substantially matches the ordinary light refractive index (n _o ) of the liquid crystal to be used, and the refractive index anisotropy Δn of the liquid crystal to be used is 0.18 or more. Yes, the average particle size of each color liquid crystal dispersed and held in the resin matrix R _X (μ
m), gap between both electrodes d _X (μm), principal wavelength λ _X of color of each light source
Is the average particle diameter R _G (μm) of the liquid crystal when the main wavelength λ _G = 540 nm of the green light source and the gap d _G (μm) between both electrodes are: A projection type active matrix liquid crystal display device characterized by satisfying the following relationship: Wherein RGB3 color light sources and three active matrix liquid crystal display device is provided, the three-color average particle diameter R _R of the liquid crystal of the liquid crystal display element, R _G, R _B, both electrode gap d _R, d _G, d _B,
The main wavelengths λ _R , λ _G , λ _B of the color of each light source are 2. The projection type active matrix liquid crystal display device according to claim 1, wherein the following relationship is satisfied. 3. The resin used in the liquid crystal resin composite is a photocurable vinyl resin, and the liquid crystal resin composite obtained by irradiating a solution in which liquid crystal and the resin are uniformly dissolved with light to cure the resin. 3. The projection type active matrix liquid crystal display device according to claim 1, wherein a body is used. 4. A projection type active matrix liquid crystal display device according to claim 1, further comprising a liquid crystal resin composite in which liquid bubbles of individual liquid crystals are communicated via a narrow space.