JP2581171B2 - Liquid crystal display device, manufacturing method thereof, and projection display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal display device and a projection display device suitable for color display.

[Prior Art] Conventionally, a liquid crystal display element in which a liquid crystal material having a smectic A phase is sandwiched between a pair of substrates with electrodes, a heating means for driving the liquid crystal element, and a voltage application for applying a voltage to the electrodes. It has been known that high-density projection display is performed by a projection-type liquid crystal display device comprising a driving device comprising means.

However, in order to perform colorization using this, it is necessary to prepare projection light sources of three colors and control each of them by the projection display device. This is because it is not practical to simultaneously project three colors using a color filter with one liquid crystal display element because the light scattering of the random alignment state of the smectic A phase is weak and the contrast ratio is deteriorated.

[Problems to be Solved by the Invention] Further, Japanese Patent Application Laid-Open No. 62-48789 discloses a method in which a film-like liquid crystal using an encapsulated smectic liquid crystal is sandwiched between a pair of substrates with electrodes, and is thermally written and erased by applying a voltage. It is shown that can be.

However, multi-color display was not possible with this method.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and is formed by polymerization and curing of a compound having a monofunctional vinyl group or a polyfunctional vinyl group and contained in a cured product matrix. A liquid crystal display element in which a film-like liquid crystal layer in which a smectic liquid crystal material is dispersed and held is sandwiched between a pair of electrodes, and a patterned color filter is formed on at least one of the electrodes. A liquid crystal display device having a driving device comprising a heating means and a voltage application means for applying a voltage to the electrodes, and formed by polymerization and curing of a compound having a monofunctional vinyl group or a polyfunctional vinyl group A film-like liquid crystal layer in which a smectic A liquid crystal substance is dispersed and held in the cured product matrix is sandwiched between a pair of substrates with electrodes. At least one liquid crystal display element with a patterned color filter formed on the surface opposite to the electrodes of the substrate with electrodes, heating means for writing on it, and voltage applied to the electrodes for simultaneous erasure A liquid crystal display device comprising: a driving device comprising a voltage applying means; and a protective plate formed of an adhesive on the outside of the electrode-attached substrate on at least the side of the film-like liquid crystal layer on which the color filter is formed. A liquid crystal display device characterized by being stacked, and a projection display device characterized by arranging a light source on the back side of those liquid crystal display devices and disposing a lens on the front side, a liquid crystal between a pair of substrates with electrodes. In a method for manufacturing a liquid crystal display device including a liquid crystal display element having a cured product matrix and a driving device, a heating unit is used as a driving device for driving the liquid crystal display element. Providing voltage applying means for applying a voltage to the electrodes, forming a patterned color filter on at least one substrate with electrodes of the liquid crystal display element, and polymerizing and curing a compound having a monofunctional vinyl group or a polyfunctional vinyl group. A method of manufacturing a liquid crystal display device, comprising forming a film-like liquid crystal layer in which a smectic liquid crystal substance is dispersed and held in a formed cured product matrix, and the liquid crystal and the cured product matrix between a pair of electrodes. In a method for manufacturing a liquid crystal display device comprising a liquid crystal display element having a liquid crystal display element and a driving device for driving the liquid crystal display element, a voltage is applied to heating means and electrodes for writing as a driving device, and voltage is simultaneously applied to the electrodes for erasing. Voltage applying means for performing
A patterned color filter is formed on at least one electrode-attached substrate of a liquid crystal display element, and a smectic A liquid crystal material is dispersed and held in a cured product matrix formed by polymerization and curing of a compound having a monofunctional vinyl group or a polyfunctional vinyl group. An object of the present invention is to provide a method of manufacturing a liquid crystal display device, wherein a thin film liquid crystal layer is formed.

According to the present invention, it is possible to easily obtain a high-density liquid crystal display device and a projection display device having a large number of pixels using a film-like liquid crystal in which a large-area element can be easily manufactured.

In the present invention, a film-like liquid crystal layer formed by polymerizing and curing a compound having a monofunctional vinyl group or a polyfunctional vinyl group and holding a smectic liquid crystal substance dispersed in a cured product matrix is used, and this is placed between a pair of substrates with electrodes. A patterned color filter is formed on at least one of the electrode-attached substrates, particularly on the surface opposite to the electrode, to form a liquid crystal display element, and a voltage is applied to the heating means and the electrode for driving the liquid crystal display element. And a driving device including a voltage applying means for performing the driving.

In particular, when a film-like liquid crystal layer using a smectic A liquid crystal material is used as a liquid crystal material, and the liquid crystal display element is scanned and heated by using a heating means, and when erasing, a voltage is applied to the electrode by a voltage applying means. It is preferable to provide a liquid crystal display device that erases all at once by applying the same.

The film-like liquid crystal layer in which the smectic liquid crystal substance is dispersed and held in the cured substance matrix may be a composite in which the cured substance is present in a network or capsule form and the liquid crystal substance is present in the gaps or voids.

As the curable compound, any material may be used as long as it cures to form a network-like or capsule-like cured product, and materials that form various polymers can be used.

In the present invention, it is preferable that a photocurable compound having a monofunctional vinyl group or a polyfunctional vinyl group is used and the photocurable compound is photocured to form a matrix of a cured product.

Specific examples of the photocurable compound include monoacrylate, diacrylate, N-substituted acrylamide,
N-vinylpyrrolidone, styrene and derivatives thereof,
Polyol acrylate, polyester acrylate,
Examples include compounds having monofunctional and polyfunctional vinyl groups represented by urethane acrylate, epoxy acrylate, silicone acrylate, fluoroalkyl acrylate, acrylate having polybutadiene skeleton, isocyanuric acid skeleton or hydantoin skeleton, unsaturated cycloacetal, and the like. .

The liquid crystal substance used in the present invention is a smectic liquid crystal substance, and may be used alone or in the form of a composition.However, the composition is used to satisfy various required performances such as an operating temperature range and an operating voltage. Would be more advantageous. In particular, when performing thermal writing by scanning with a heating means, it is preferable to use a smectic liquid crystal material having a smectic A phase.
In this case, similar to a normal smectic liquid crystal display device having a smectic A phase, a heating means is used for writing, and a voltage applying means is used for erasing by simultaneously applying a voltage for erasing. can do.

The liquid crystal material may have a nematic phase on the smectic A phase.

Specifically, when a normal smectic A liquid crystal material having a positive dielectric anisotropy is used, when a portion heated and melted by a heating means such as a laser is cooled with a voltage applied thereto, the liquid crystal is cooled. The molecules are oriented substantially perpendicular to or near the substrate. By setting the refractive index of the liquid crystal material to match the refractive index of the cured product in this state, light is transmitted. On the other hand, a portion cooled without applying a voltage is in a state close to a state where liquid crystal molecules are randomly aligned. Thus, in this state, the refractive index of the liquid crystal material does not match the refractive index of the cured product, and light is scattered. Accordingly, when a light source is arranged on one side and projected with light, the pixels where light is scattered become darker, the pixels where light is transmitted become brighter, and an image is displayed.

According to this method, a high-density projection display device can be easily obtained.

In particular, by using a liquid crystal substance and a photo-curable compound and undergoing a photo-curing process, the liquid crystal substance and the cured product are fixed by phase separation, resulting in a structure in which the liquid crystal substance is dispersed in a matrix of the cured product. And the distribution of the cured product becomes uniform,
An element excellent in appearance quality and productivity can be easily manufactured.

In producing the device of the present invention, the curable compound and the liquid crystal substance may be a mixture of about 5:95 to 40:60, and may be used as a liquid or a viscous substance.

Further, a mixture of a curable compound and a liquid crystal substance for forming a film-like liquid crystal layer may be used alone or in combination with the curable compound and the liquid crystal substance, and a modifying agent necessary for element preparation, prepared. It may contain an element modifier or the like. Specifically, it contains a crosslinking agent, a surfactant, a diluent, a thickener, a defoaming agent, an adhesion-imparting agent, a stabilizer, an absorbent, a polymerization accelerator, a chain transfer agent, a polymerization inhibitor and the like. Good.

When manufacturing the device of the present invention, the mixture of the curable compound and the liquid crystal substance to be prepared may be a liquid or a viscous material and may be mixed evenly, so that an optimum one may be selected depending on the device manufacturing method. You can choose. For example, it is generally more convenient to inject liquid in a cell in which glass substrates with transparent electrodes such as In ₂ O ₃ --SnO ₂ and SnO ₂ are arranged so as to face each other and the periphery is sealed. In general, when applying to a substrate such as plastic or glass attached thereto and overlaying opposing substrates, the viscous state is more convenient.

The gap between the substrates can be operated at 5 to 100 μm, but it is appropriate to set it to 7 to 40 μm in consideration of the applied voltage and the contrast at ON / OFF.

A patterned color filter is formed on at least one of the substrates with electrodes used in the present invention. This color filter may be formed on the surface on which the electrodes are formed, or may be formed on the surface opposite to the surface on which the electrodes are formed.

When a color filter is formed on the surface on which the electrode is formed, it may be formed between the substrate and the electrode, or may be formed on the electrode.

In particular, in the case of a projection display device, even if a color filter is formed on the surface opposite to the surface on which the electrodes are formed, the problem of parallax is small and manufacturing is easy, which is preferable.

The pattern of the color filter may be large or small, but is preferably 1 mm or less in width for accurate display. The pattern is preferably a mosaic or stripe.

Various combinations of the colors are possible, but in the case of performing full color display, it is general to select red, blue and green.

As a method for forming the color filter on the substrate, a known color filter forming method can be used, and a gelatin dyeing method, a printing method, a sublimation dyeing method, an electrodeposition method, and the like can be used.

The thickness of the substrate on which the color filter is formed has almost no problem when the color filter is formed on the electrode surface side, and may be appropriately determined depending on the required strength. When the color filter is formed on the side opposite to the electrode surface, if it is too thick, the resolution will be reduced. In this case, the thickness is preferably not more than half the width of the pattern of the color filter, and particularly preferably not more than 250 μm. However, if the thickness is too small, there is a problem in strength. Therefore, the thickness is preferably 50 μm or more.

There is no particular limitation on the substrate on which the color filter is not formed, since it is sufficient to consider only the problem of strength.
However, when placed close to a powerful light source,
Consider heat resistance, ease of cooling, infrared reflection function, etc.

When a substrate having a thickness of 300 μm or more is used, a glass substrate is suitable. When a thin substrate having a thickness of 250 μm or less is used, a plastic substrate is preferably used.

Further, by using a plastic substrate as the substrate with electrodes, a long liquid crystal display element using a continuous plastic film can be easily manufactured.

By using such a smectic liquid crystal material and a film-like liquid crystal made of a matrix of a photocurable compound having a monofunctional vinyl group or a polyfunctional vinyl group, there is a risk that the upper and lower transparent electrodes may be short-circuited even in a large area. Low,
A highly reliable liquid crystal display element can be manufactured with extremely high productivity. In order to reduce unevenness in the light transmission state,
It is better that the substrate gap is constant to some extent. For this reason, it is preferable to dispose a spacer for controlling the gap such as glass particles, plastic particles, and ceramic particles in the gap between the substrates. Specifically, a mixture of a curable compound and a liquid crystal material is supplied on a substrate with a spacer for controlling the gap between the substrates supplied, or a spacer is supplied before or after supplying the mixture, and the other substrate is superimposed. What should I do? In this case, a more uniform substrate gap is likely to be obtained by applying pressure after overlapping and then curing.

Such a liquid crystal display element can be used as a display element for large-area, high-density display.

This liquid crystal display element has various types such as a case where a plastic is laminated with a protective plate such as glass when the substrate is made of plastic or thin glass, or a case where the substrate is made of tempered glass, laminated glass, lined glass or the like for further protection. Is applicable.

In particular, when the color filter is formed on the side opposite to the electrode surface, it also serves to protect the color filter. Therefore, it is preferable to laminate the protection plate with an adhesive.

In particular, a plastic substrate is used as a substrate with electrodes to form a liquid crystal display element, and an electrode lead-out line is provided, and this is interposed between two glass plates, which are slightly larger than the liquid crystal display element, via a sheet-like adhesive such as polyvinyl butyral. Pinch,
By heating or light irradiation, the sheet adhesive is cured,
It is preferable that the liquid crystal display element and the glass plate are integrated and used as a laminated glass. Above all, by using polyvinyl butyral as the sheet adhesive, a structure very similar to ordinary laminated glass can be obtained.

In the present invention, the electrode is a transparent electrode because it is usually a transmission type. Of course, a metal lead portion for lowering the resistance may be provided in a part thereof. In addition, when used as a reflective display device, one electrode may be a reflective electrode.

In the present invention, the electrodes on each substrate are divided into a plurality of electrode groups. For example, by forming a device using a first electrode-attached substrate having 1000 stripe-shaped electrodes and a second electrode-attached substrate having 1000 stripe-shaped electrodes in a direction perpendicular to the first electrode, 1 million pixels can be obtained. Display device. The individual electrodes are connected to voltage applying means, and a voltage is applied from the voltage applying means to control the voltage applied between the electrodes of the individual pixels, while irradiating a laser beam from a laser device as a heating means. By heating individual pixels in this way, transmission and scattering of individual pixels can be controlled.

In order to manufacture this liquid crystal display element, an empty cell is formed in advance in the same manner as a conventional ordinary twisted nematic liquid crystal display element, and a mixture composed of a liquid crystal substance and a curable compound is injected into the empty cell and cured. Good. Alternatively, the mixture may be supplied onto one substrate and cured, and then the other substrate may be stacked and laminated, or the other substrate may be laminated and cured.

Also in this case, two substrates having a desired shape are prepared, and a liquid crystal display element may be manufactured by combining them, or a continuous plastic film substrate may be used, or a long glass substrate may be used. It may be manufactured by a method of cutting later.

According to the present invention, high-density display can be easily performed by using a driving device including a heating unit such as a laser and a voltage applying unit for applying a voltage to the electrodes as described above.

The heating means may be any means capable of locally causing a phase transition of the liquid crystal. Therefore, the heating means may be integrated with the display element, or may be separated. In the case of being integrated, an electric current may be applied to the electrodes of one or both of the substrates with electrodes to heat them. This electrode may also be used as a display drive electrode, or a heating electrode may be separately provided. In addition, when not integrated, a laser is often used. Therefore, it is preferable to mix a light-absorbing substance such as a pigment or a dye that absorbs laser light into the cured product matrix or the liquid crystal substance.

When a voltage for driving is applied by the voltage applying means, an AC voltage that changes the alignment of the liquid crystal may be applied. Specifically, an AC voltage of about 10 to 150 V and about 10 to 1000 Hz may be used as long as the voltage changes the light transmission state of the element or a voltage that can obtain a certain orientation.

The liquid crystal display device of the present invention is another display, a normal TN liquid crystal display device, an electrochromic display device,
It may be used by being laminated with an electroluminescence display element or the like, and various applications are possible.

In addition, a light source is arranged on the back side of the liquid crystal display device, and a lens is arranged on the front side, so that light emitted from the light source passes through the liquid crystal display device and is projected by the lens on the front side, so that one light source is provided. And a multi-color or full-color projection display device can be obtained.

In addition, a reflective electrode is used in this liquid crystal display device or a reflective film is disposed on the back side, a light source and a half mirror are disposed on the front side, and light emitted from the light source passes through the half mirror and enters the liquid crystal display device. Alternatively, the light may be reflected on the back side, pass through the liquid crystal display device again, be reflected on the half mirror, guided to the lens, and projected.

This is because the liquid crystal display device of the present invention not only utilizes the transmission scattering action of the smectic A liquid crystal substance alone, but also uses the transmission scattering action based on the difference in the refractive index between the matrix of the cured product and the smectic A liquid crystal substance. Therefore, a sufficient contrast ratio can be obtained and a multi-color or full-color projection display device can be obtained with one liquid crystal display device. That is, when a voltage is applied to orient the liquid crystal material, the smectic A liquid crystal material is arranged in a specific direction and becomes a transparent state at the same time, and at the same time, the refractive index of the matrix of the cured product and the ordinary light refractive index of the smectic A liquid crystal material or abnormal The light refractive index matches, and the film-like liquid crystal layer is in a transmission state.
On the other hand, when no voltage is applied, the smectic A liquid crystal material loses alignment and becomes a scattering state itself, and at the same time, the refractive index of the matrix of the cured product differs from the ordinary refractive index or the extraordinary refractive index of the smectic A liquid crystal material. Then, the film-like liquid crystal layer is in a scattering state higher than the scattering state of the smectic A liquid crystal substance alone due to both effects.

[Examples] Hereinafter, the present invention will be specifically described with reference to examples. Examples 1 and 2 are reference examples.

Example 1 In 100 parts of an aqueous polyvinyl alcohol solution, 8 parts of a smectic A liquid crystal composition (“S-7” manufactured by BDH) was dispersed. This emulsified dispersion was supplied onto a polyethylene terephthalate substrate with ITO patterned into a stripe having a thickness of 125 μm and dried.

Next, a liquid crystal display device was manufactured by superposing a polyethylene terephthalate substrate provided with ITO patterned in a stripe shape on one surface and a mosaic shape of 0.3 mm square with red, green and blue color filters on the other surface. The substrate gap is
It was 15 μm.

Example 2 Instead of the polyvinyl alcohol aqueous solution of Example 1, 7%
A projection type liquid crystal display device was obtained in the same manner as in Example 1 except that 100 parts of polyurethane latex was used.

Example 3 One part of an acrylic photopolymerizable resin, one part of a smectic A liquid crystal composition ("S-7" manufactured by BDH), and 0.01 part of benzoin isopropyl ether as a photocuring initiator were uniformly dissolved, and the particles were added thereto. A mixture obtained by mixing a plastic spacer having a diameter of 15 μm was supplied onto a plastic film substrate with ITO as in Example 1, and immediately, a plastic film substrate with ITO provided with a color filter on the opposite surface as in Example 1 was overlaid. A liquid crystal display device was manufactured by irradiating UV and photo-curing to phase-separate the liquid crystal substance and the matrix of the cured product.

Example 4 In 9 parts of ethylhexyl acrylate and 6 parts of an acrylic oligomer ("M-1200" manufactured by Toa Gosei Chemical Co., Ltd.), 35 parts of a smectic liquid crystal ("S-7" manufactured by BDH) and a photocuring initiator ("Merck") 0.5 parts of Darocure 1116 were uniformly dissolved, sandwiched between substrates as in Example 3, and irradiated with UV while applying an AC voltage of 50 Hz between the electrodes to cure the liquid crystal material and the matrix of the cured product together with photo-curing. The liquid crystal display device was manufactured by being separated.

The light transmittance of the liquid crystal optical element manufactured in this manner immediately after curing depends on the voltage applied at the time of curing, but once the manufactured liquid crystal optical element is heated to the isotropic phase of the liquid crystal once and then cooled, Regardless of the applied voltage at the time of manufacture, a scattering state was obtained, and the device could be driven with an applied voltage lower than that obtained when curing was performed without applying a voltage between the electrodes.

Example 5 A polymethyl methacrylate plate containing an ultraviolet absorbent as a protective plate was adhered to the color filter side of the liquid crystal display devices of Examples 3 and 4 with an adhesive.

The color filter was protected by this protective plate, and the reliability of the liquid crystal display device was improved.

Example 6 A glass plate was laminated on both sides of the liquid crystal display devices of Examples 3 and 4 with a polyvinyl butyral film interposed therebetween, and then heated and pressed to produce a laminated glass liquid crystal display device.

This liquid crystal display element had high strength and excellent reliability.

Example 7 The electrodes of Examples 3 to 6 and the liquid crystal display element were connected to
V, 50Hz), a semiconductor laser is used as a heating means, a three-wavelength fluorescent lamp is placed on the back side, and a lens is placed on the front side to form a projection display device. was gotten.

[Effects of the Invention] As described above, the present invention provides a novel liquid crystal display device, which is formed by polymerization and curing of a compound having a monofunctional vinyl group or a polyfunctional vinyl group, and is formed in a cured product matrix. A liquid crystal display device in which a film-like liquid crystal layer in which a smectic liquid crystal material is dispersed and held is sandwiched between a pair of substrates with electrodes. According to the present invention, a liquid crystal display device having a large area and displaying a desired color And a projection display device can be easily provided.

In the present invention, by using a mixture of a curable compound and a smectic liquid crystal substance to form a film-like liquid crystal layer, productivity is excellent, and both small and large liquid crystal display devices can be easily manufactured.

In the present invention, since a smectic liquid crystal material is used,
Even if the liquid crystal optical element has a structure in which a liquid crystal substance is dispersed in a matrix of a cured product formed by polymerizing and curing a compound having a monofunctional vinyl group or a polyfunctional vinyl group, which is capable of displaying with memory properties, it is possible to use a dot. Matrix display becomes possible.

Also, unlike a liquid crystal display device using a normal liquid liquid crystal material, since it is not in a liquid state after curing, there is little risk of short circuit between substrates, and a large liquid crystal display device, for example, a 1 m square liquid crystal display device is also available. Can be easily manufactured.

Further, by providing a protective plate on at least the color filter surface of the substrate, the color filter is protected and reliability is improved. In particular, by providing the protective plates on both sides, breakage hardly occurs.

In particular, when a plastic substrate is used for the substrate,
Although the productivity is good, the strength is inferior, so that when the area is increased, it is easily broken or curved. For this reason, the effect of providing the protective plates on both sides is great. Above all, by using a glass plate as a protective plate and bonding with an adhesive material such as polyvinyl butyral, the structure becomes similar to that of a laminated glass, and safety and reliability are improved.

The liquid crystal display device of the present invention is an element having excellent appearance quality and productivity, and is suitable for large-area, curved display.
In particular, it is suitable for a projection type liquid crystal display device.

The present invention is also applicable to various applications within a range that does not impair the effects of the present invention.

Claims (6)

(57) [Claims] 1. A film-like liquid crystal layer in which a smectic liquid crystal substance is dispersed and held in a cured product matrix formed by polymerizing and curing a compound having a monofunctional vinyl group or a polyfunctional vinyl group, between a pair of substrates with electrodes. A liquid crystal display element formed by forming a patterned color filter on at least one substrate with electrodes, and a driving device including a heating unit for driving the device and a voltage application unit for applying a voltage to the electrodes. A liquid crystal display device comprising: 2. A film-like liquid crystal layer in which a smectic A liquid crystal substance is dispersed and held in a cured product matrix formed by polymerizing and curing a compound having a monofunctional vinyl group or a polyfunctional vinyl group, between a pair of substrates with electrodes. A liquid crystal display element in which a patterned color filter is formed on the surface opposite to the electrodes of at least one electrode-attached substrate, and a heating means for writing the data and erasing all at once by applying a voltage to the electrodes. A liquid crystal display device comprising: a driving device including a voltage application unit for performing the operation. 3. The liquid crystal display device according to claim 1, wherein a protective plate is laminated with an adhesive on the film-like liquid crystal layer at least on the outer side of the electrode-attached substrate on which the color filter is formed. Display device. 4. A projection display device comprising a liquid crystal display device according to claim 1, a light source disposed on the back side, and a lens disposed on the front side. 5. A method of manufacturing a liquid crystal display device comprising: a liquid crystal display element having a liquid crystal and a cured product matrix between a pair of substrates with electrodes; and a driving device for driving the liquid crystal display element. As a heating means and a voltage applying means for applying a voltage to the electrodes are provided, a patterned color filter is formed on at least one electrode-attached substrate of the liquid crystal display element, and a compound having a monofunctional vinyl group or a polyfunctional vinyl group is formed. A method for manufacturing a liquid crystal display device, comprising forming a film-like liquid crystal layer in which a smectic liquid crystal substance is dispersed and held in a cured product matrix formed by polymerization curing. 6. A method for manufacturing a liquid crystal display device, comprising: a liquid crystal display element having a liquid crystal and a cured product matrix between a pair of electrode-attached substrates; and a driving device for driving the liquid crystal display element. A heating means for writing and a voltage applying means for simultaneously applying voltage to the electrodes and erasing the electrodes are provided, and a patterned color filter is formed on at least one electrode-attached substrate of the liquid crystal display element, and a monofunctional A method for producing a liquid crystal display device, comprising forming a film-like liquid crystal layer in which a smectic A liquid crystal material is dispersed and held in a cured product matrix formed by polymerization and curing of a compound having a vinyl group or a polyfunctional vinyl group.