JP2001183653A - Projection type liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a projection type liquid crystal display device capable of displaying a bright image for a long period of time. SOLUTION: A straight line having a transmittance of 30% or more and 70% or less for linearly polarized light having a vibration plane parallel to an absorption axis between a light source and a light source side linear polarizing plate in a wavelength range of 430 to 700 nm. A projection type liquid crystal display device comprising a polarizing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection type liquid crystal display device.

[0002]

2. Description of the Related Art A projection type liquid crystal display device, also called a liquid crystal projector, is a liquid crystal display device used for displaying an image enlarged and projected on a screen. As such a projection type liquid crystal display device, for example, a device including a light source, a liquid crystal cell, and a magnifying lens is known. A light source side linear polarizer is disposed on the light source side of the liquid crystal cell, and a screen side linear polarizer is disposed on the screen side. A polarizing plate is arranged and used.
Here, the linear polarizing plate is an optical component having a function of absorbing linearly polarized light having a vibration plane parallel to the absorption axis direction and transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis direction. The linearly polarized light absorbed by the linearly polarizing plate becomes heat.

In such a projection type liquid crystal display device, light emitted from a light source is divided into a light source side linear polarizing plate disposed on the light source side of the liquid crystal cell, a liquid crystal cell, and a screen side linearly polarized light disposed on the screen side of the liquid crystal cell. An image is formed by transmitting through the plate in this order, and then enlarged and projected on a screen by a magnifying lens.

[0004] The image projected on the screen is preferably bright. In order to brighten such an image, the brightness of the light source may be increased. For this purpose, a metal halide lamp, a high-pressure mercury lamp, or the like having a relatively high brightness is preferably used as the light source.

However, since these light sources generate ultraviolet light and infrared light simultaneously with visible light, there has been a problem that the linear polarizing plate on the light source side is particularly liable to be deteriorated. When the light source-side linear polarizing plate is deteriorated, an image displayed on the screen tends to be dark.

In order to solve such a problem, a projection type liquid crystal display device in which an ultraviolet cut filter and an infrared cut filter are arranged between a light source and a light source side linear polarizing plate is also known. It could not be said that deterioration could be sufficiently prevented.

[0007]

Therefore, the present inventor has proposed:
As a result of intensive studies to develop a projection type liquid crystal display device capable of displaying a bright image over a long period of time, a linear polarizer is further disposed between the light source and the light source side linear polarizer, and the light source and the light source side linear polarizer are arranged. As the linear polarizer disposed between the polarizer and the linear polarizer, a linear polarizer having a specific range of transmittance for linearly polarized light having a vibration plane parallel to the absorption axis in a wavelength range of 430 to 700 nm was used. The projection type liquid crystal display device can prevent the deterioration of the light source side linear polarizing plate, and the linear polarizing plate disposed between the light source and the light source side linear polarizing plate hardly deteriorates. They have found that this is possible, and have reached the present invention.

[0008]

That is, according to the present invention, the transmittance of a linearly polarized light having a vibration plane parallel to an absorption axis between a light source and a linearly polarizing plate on the light source side has a wavelength of 430.
Another object of the present invention is to provide a projection type liquid crystal display device in which a linear polarizing plate of 30% or more and 70% or less in a range of from 700 to 700 nm is arranged.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type liquid crystal display device of the present invention
Wavelengths of 430 to 70 for linearly polarized light having a vibration plane parallel to the absorption axis between the light source and the light source side linear polarizer
A linear polarizer having a transmittance at 0 nm of 30% or more is provided. When the transmittance of the linear polarizing plate disposed between the light source and the light source-side linear polarizing plate is less than 30%, the linear polarizing plate tends to deteriorate, and preferably 35%.
That is all. Further, if the transmittance exceeds 70%, there is a tendency that deterioration of the light source side linear polarizing plate cannot be sufficiently prevented,
Preferably it is 65% or less. Such transmittance has a wavelength of 4
3 in the range of less than 30 nm or more than 700 nm
0% or more may be less than 30%,
Further, it may be 70% or less, or may exceed 70%.

On the other hand, the transmittance of a linearly polarized light having a vibration plane orthogonal to the absorption axis of a linearly polarizing plate disposed between the light source and the linearly polarizing plate on the light source side has a brightness of a displayed image, In terms of contrast, it is usually at least 80%, preferably at least 85%.

As such a linear polarizing plate, for example, a polyvinyl alcohol resin film in which a dichroic dye is adsorbed and oriented is exemplified. The dichroic dye may be iodine, but a dichroic dye is preferably used in terms of durability.
As the dichroic dye, the same dichroic dye as used for a normal polarizing plate can be used.

Examples of the polyvinyl alcohol resin film include, for example, a film obtained by saponifying a polyvinyl acetate resin film, a polyvinyl formal film and a polyvinyl acetal film obtained by modifying the same. Examples of the polyvinyl acetate resin include polyvinyl acetate, vinyl acetate, and copolymers of other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like.

The degree of saponification of the polyvinyl alcohol resin film is usually 80 to 100%, preferably 98% in terms of molar ratio.
And the degree of polymerization is usually about 1,000 to 10,000, preferably about 1500 to 50.
About 00 or less, more preferably about 2000 or more and 50
It is about 00 or less.

In order to cause the dichroic dye to be adsorbed and oriented on the polyvinyl alcohol resin film, for example, the polyvinyl alcohol resin film may be stretched and dyed with the dichroic dye. Dyeing is usually performed by immersing a polyvinyl alcohol resin film in an aqueous solution of a dichroic dye.

The amount of the dichroic dye used in the aqueous solution of the dichroic dye is usually from 0.0001 to 1 per 100 parts by weight of water.
And the temperature of the aqueous solution is usually 30 to 85 parts by weight.
° C, preferably about 60 to 75 ° C. The aqueous solution of the dichroic dye may contain a dyeing aid such as bow glass.
In the case of using glass nitrate, its usage is about 0.1 to 10 parts by weight with respect to 100 parts by weight of water. The immersion time of the dichroic dye in the aqueous solution is usually about 0.1 to 60 seconds. The polyvinyl alcohol resin film may be dipped in water before dyeing.

The stretching is usually uniaxial stretching. The stretching method is not particularly limited, and may be dry stretching or wet stretching. Examples of the dry stretching include, for example, a method in which a polyvinyl alcohol resin film is brought into contact with a rotating heating roll while applying a backward tension to make it uniaxially longitudinally stretched, and a method in which the film is passed between a pair of heating rolls and uniaxially compressed and stretched. Can be The temperature of the heating roll in these methods is not lower than the glass transition temperature of the polyvinyl alcohol resin film and is usually not higher than 160 ° C., preferably not higher than 80 ° C.
It is about 130 ° C. or more and about 130 ° C. Stretching ratio is usually 4
It is at least 8 times, preferably at most 8 times.

The polyvinyl alcohol resin film may be stretched before dyeing, may be stretched during dyeing, or may be stretched after dyeing.

The polyvinyl alcohol resin film on which the dichroic dye is adsorbed and oriented is usually treated with boric acid. The boric acid treatment is performed, for example, by immersing the polyvinyl alcohol resin film in a boric acid aqueous solution. The amount of boric acid used in the boric acid aqueous solution is 100 parts of water.
Usually about 2 to 15 parts by weight, preferably 5 to 5 parts by weight
About 12 parts by weight. The temperature of the boric acid aqueous solution is usually 5
The temperature is about 0 to 85 ° C, preferably about 65 to 80 ° C.
The immersion time is usually about 100 to 1200 seconds, preferably 1
It is about 50 to 600 seconds. After immersion, the film is washed with water and dried to obtain a polyvinyl alcohol resin film in which the dichroic dye is adsorbed and oriented.

The thickness of the polyvinyl alcohol resin film on which the dichroic dye is adsorbed and oriented is usually 1
It is about 0 to 40 μm.

In order to obtain a linear polarizing plate applied to the projection type liquid crystal display device of the present invention, the immersion time of the dichroic dye in the aqueous solution in dyeing, the amount of the dichroic dye used in the aqueous solution, the dyeing assistant And the temperature of the aqueous solution may be appropriately selected.

The polyvinyl alcohol resin film thus obtained can be used as it is as the light source and the light source side linear polarizing plate of the projection type liquid crystal display device of the present invention, but usually a protective plate is laminated on one or both sides of the film. Used as a linear polarizing plate.

Examples of the protective plate include cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose; acrylic resins; polyester resins such as polyethylene terephthalate; polyolefin resins such as polyethylene and polypropylene;
A film made of a cyclic polyolefin resin such as polyarylate resin, polyether sulfone resin, and polynorbornene is exemplified. The thickness of the protective plate is usually 50 to 2
It is about 00 μm.

Such a protective plate may contain additives such as an ultraviolet absorber. As a protective plate containing an ultraviolet absorber, for example, cellulose acetate resin films such as "Konica KC80UVSF" (manufactured by Konica Corporation) and "Konica KC80UVN" (manufactured by Konica Corporation) are commercially available.

The protective plate is usually laminated on a polyvinyl alcohol resin film in which dichroic dyes are adsorbed and oriented via a transparent and optically isotropic adhesive such as a polyvinyl alcohol-based water-soluble adhesive.

It is preferable that such a linear polarizing plate has a surface reflectance of 0.3% or less. The surface reflectance is 0.
If it exceeds 3%, the transmittance of the linearly polarized light having a vibration plane orthogonal to the absorption axis becomes small, and the displayed image tends to be dark, and irregular reflection occurs inside the projection type liquid crystal display device. This may cause the contrast of the displayed image to decrease.

In order to make the surface reflectance 0.3% or less, for example, an antireflection layer may be provided on the surface of the linear polarizing plate. As the antireflection layer, for example, a layer in which one or two or more layers made of an inorganic substance such as a metal, a metal oxide, and a metal fluoride, an organic substance, and the like are stacked is exemplified. Examples of the metal include silver and the like, examples of the metal oxide include titanium oxide, silicon oxide and tantalum oxide, and examples of the metal fluoride include magnesium fluoride and the like. Examples of the organic substance include a fluorine-based resin.

Such an antireflection layer is formed, for example, by a vacuum evaporation method,
Physical vapor deposition such as sputtering (PVD (Phys
ical vapor deposition) method, coating method and the like can be provided on the surface of the linear polarizing plate. In the case where the linear polarizing plate is one in which a protective plate is laminated on one or both surfaces of a polyvinyl alcohol resin film in which a dichroic dye is adsorbed and oriented, even if the protective plate is provided with an antireflection layer in advance. Good. From the viewpoint of adhesion to the antireflection layer, a hard coat layer may be provided on the surface of the linear polarizing plate in advance, or the surface may be subjected to a surface modification treatment such as a corona treatment.

Such a linear polarizing plate has a surface contact angle of 80 °.
The following is preferred. When the surface contact angle is less than 80 °, when used in a projection type liquid crystal display device for a long period of time, foreign substances such as dust and dust are liable to adhere to the surface and the contrast of the displayed image is reduced. It is easy to perform, and it is more preferably 100 ° or more. Such a surface contact angle is usually 180 ° or less.

When an antireflection layer is formed on the surface of a linear polarizing plate, the above contact angle may be satisfied depending on the type of the antireflection layer.

On the other hand, when the anti-reflection layer is not provided, or when the anti-reflection layer is made of metal, metal oxide, metal fluoride, or the like, the above contact angle is not satisfied. In this case, a layer similar to that usually used for preventing surface contamination, for example, a layer formed from a fluorine compound may be provided. Examples of the fluorine compound include a fluorine-containing silane compound. As such a fluorine-containing silane compound, for example, a compound represented by the general formula (1) (In the formula, R ^f is a linear or branched perfluoroalkyl group having 1 to 16 carbon atoms, X is an iodine atom or a hydrogen atom, Y is a hydrogen atom or a lower alkyl group, Z is a fluorine atom or a trialkyl group. A fluoromethyl group, R ¹ is a hydrolyzable group, R ² is a hydrogen atom or an inert monovalent organic group, a is an integer of 0 to 200, b is an integer of 0 to 200, c Is an integer of 0 to 200, d is an integer of 0 to 200, e is 0 or 1, m is an integer of 0 to 2, and n is 0 to 200.
2 represents an integer, and p represents an integer of 1 or more. Fluorinated silane compound represented by the formula (JP-A-1-294709)
Publication).

Such a linearly polarizing plate can be suitably used as a linearly polarizing plate for a projection type liquid crystal display device. For example, the linearly polarizing plate can be used as an optical component by being attached to a base material in the projection type liquid crystal display device of the present invention. Can be. As a substrate,
For example, a transparent substrate having a flat surface such as a flat glass, a plano-convex lens, and a plano-concave lens is preferably used. An antireflection layer may be provided on the side of the substrate opposite to the side on which the linear polarizing plate is adhered. Further, a dichroic process or the like may be performed so as to transmit only light of a predetermined wavelength. Further, a retardation plate or the like may be attached to the linearly polarizing plate.

Such a linear polarizing plate is used by being disposed between the light source and the light source side linear polarizing plate disposed on the light source side of the liquid crystal cell in the linear polarizing plate for a projection type liquid crystal display device of the present invention. Since an ultraviolet cut filter and an infrared cut filter are usually arranged between the light source and the light source side linear polarizer, the linear polarizer of the present invention is arranged between the light source and the ultraviolet cut filter and the infrared cut filter. However, it is preferable to dispose it between the ultraviolet ray cut filter and the infrared ray cut filter and the light source side linearly polarizing plate in that deterioration due to ultraviolet rays or infrared rays is small. Here, the ultraviolet cut filter and the infrared cut filter may have the ultraviolet cut filter disposed on the light source side, the infrared cut filter may be disposed on the light source side, and have the functions of the ultraviolet cut filter and the infrared cut filter. It may be a band pass filter. The linearly polarizing plate may be laminated in close contact with the light source side linearly polarizing plate, but it is preferable that these are disposed via an air layer from the viewpoint of sufficient cooling. When the linear polarizing plate is in contact with the air layer, the surface reflectance of the surface in contact with the air layer is preferably 0.3% or less, and the surface contact angle is preferably 80 ° or more.

In the projection type liquid crystal display device of the present invention, the same light source side linear polarization plate, liquid crystal cell, screen side linear polarization plate and magnifying lens as those used in the conventional projection type liquid crystal display device are used. be able to.

In the projection type liquid crystal display device of the present invention, light emitted from the light source is converted into a linear light having a vibration plane parallel to the absorption axis by a linear polarizing plate disposed between the light source and the light source side linear polarizing plate. Since the polarized light enters the light source side linear polarizer after being reduced to 70% to 30% in the wavelength range of 430 to 700 nm, the amount of light absorbed by the light source side linear polarizer depends on the light source and the light source side linear polarizer. Of the amount of light absorbed by the light source side linear polarizer in the conventional projection type liquid crystal display device in which no linear polarizer is disposed between
% To about 30%. Therefore, the light source side linear polarizing plate of the projection type liquid crystal display device of the present invention has a heating value of 30% of the heating value of the light source side linear polarizing plate in the conventional projection type liquid crystal display device.
% To about 70%, the temperature can be kept low for a long time, and there is almost no deterioration.

[0035]

The projection type liquid crystal display device of the present invention can maintain the brightness of an image displayed on a screen even when used for a long period of time.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The linear polarizing plates obtained in the examples were evaluated by the following methods. (1) Transmittance for linearly polarized light having a vibration plane parallel to the absorption axis Measured using a spectrophotometer “UV2200” manufactured by Shimadzu Corporation. (2) Surface contact angle The contact angle was measured using a contact angle meter “CA-X type” manufactured by Kyowa Interface Science Co., Ltd.

Example 1 A polyvinyl alcohol film (thickness: 75 μm) having a degree of polymerization of 2400 was brought into contact with a rotating heating roll while applying backward tension, and stretched uniaxially at a heating temperature of about 120 ° C. and a stretching ratio of about 5 times. 6 in 54 ° C water while maintaining tension
After immersion for 0 second, 5 parts consisting of water (100 parts by weight), a dichroic dye (0.6 parts by weight) and borate (2 parts by weight)
It was immersed in a 9 ° C. aqueous solution for 5 seconds. Next, it was immersed in a 74 ° C. aqueous solution consisting of 100 parts by weight of water and 7.5 parts by weight of boric acid for 300 seconds. Thereafter, the film was washed with water and dried to obtain a polyvinyl alcohol film on which a dichroic dye was adsorbed and oriented.

On both sides of this film, a triacetyl cellulose film (“Konica KC80UVN”, Konica Corporation)
Was laminated using a polyvinyl alcohol-based water-soluble adhesive to obtain a linear polarizing plate. One triacetyl cellulose film had a hard coat layer on one side, and was laminated to a polyvinyl alcohol film on the side opposite to the hard coat layer side. When this linear polarizing plate was irradiated with linearly polarized light having a vibration plane parallel to the absorption axis,
Its transmittance is 3 in the wavelength range of 430 to 700 nm.
The range was from 8.6% to 52.7%. FIG. 1 shows the spectrum of the transmitted light.

An antireflection layer was provided on the hard coat surface of this polarizing plate by a vacuum evaporation method. Then, the general formula (2) Fluorine-containing silane compound represented by the formula (polymerization degree is 1000)
Was applied. The surface contact angle was 100 degrees or more.

An optical component obtained by adhering this linear polarizing plate to a flat glass having an antireflection layer on one side is used as a light source, a band-pass filter also serving as an ultraviolet cut filter and an infrared cut filter, a light source side linear polarizing plate, a liquid crystal. The projection type liquid crystal display device in which the cell and the screen side linear polarizer are arranged on the optical path in this order between the band-pass filter of the projection type liquid crystal display device and the light source side linear polarizer has an image displayed on the screen. Can be maintained bright for a long period of time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a transmittance spectrum when a linearly polarized light having a vibration plane parallel to an absorption axis is irradiated on the linearly polarizing plate obtained in Example 1, and the vertical axis indicates transmittance (%). , And the horizontal axis indicates the wavelength (nm).

Claims (9)

[Claims] 1. A transmittance of linearly polarized light having a vibration plane parallel to an absorption axis between a light source and a light source side linear polarizing plate is 30% or more and 70% or less in a wavelength range of 430 to 700 nm. A projection type liquid crystal display device comprising a linear polarizing plate. 2. The projection type liquid crystal display device according to claim 1, wherein the linear polarizing plate according to claim 1 is a linear polarizing plate comprising a polyvinyl alcohol resin film on which a dichroic dye is adsorbed and oriented. 3. The projection type liquid crystal display device according to claim 1, wherein the surface reflectance of the linear polarizing plate according to claim 1 is 0.3% or less. 4. The projection type liquid crystal display according to claim 1, wherein the surface contact angle of the linear polarizing plate according to claim 1 is 80 ° or more. 5. A linear polarizing plate, wherein the transmittance for linearly polarized light having a vibration plane parallel to the absorption axis is 30% or more and 70% or less in a wavelength range of 430 to 700 nm. 6. The linear polarizing plate according to claim 5, comprising a polyvinyl alcohol resin film on which a dichroic dye is adsorbed and oriented. 7. The method according to claim 5, wherein the surface reflectance is 0.3% or less.
The linear polarizing plate according to 1. 8. The linearly polarizing plate according to claim 5, wherein the surface contact angle is 80 ° or more. 9. An optical component comprising the linear polarizing plate according to claim 5 adhered to a substrate.