CN100367050C - Optical compensation plate and projection type liquid crystal display device using optical compensation plate - Google Patents

Abstract

Provides an optical compensation plate that improves the contrast of a projection-type liquid crystal display device and can realize continuous high-quality display for a long time, and is used in a projection-type liquid crystal display device. The optical compensation plate (20) consists of a transparent diaphragm (21) with a transmittance of less than 10% at a wavelength of 380nm and a reflectivity of less than 2% at a wavelength of 550nm on the surface in contact with the air. 31) An optical compensation film (30) formed by coating a liquid crystal compound layer (32) and a transparent glass plate (23) are laminated. It can be formed by stacking two optical compensation films, and their respective orientation axes are arranged approximately vertically and intersecting. Fit each other. The optical compensation plate (20) is arranged on one side of the liquid crystal box (7), and the transparent film (21) is positioned on the side of the liquid crystal box 7, thereby forming a projection type liquid crystal display device.

Description

Optical compensation plate and projection type liquid crystal display device using optical compensation plate

technical field

The present invention relates to an optical compensation plate suitable for a projection type liquid crystal display device, and also relates to a projection type liquid crystal display device using it.

Background technique

A projection type liquid crystal display device is called a liquid crystal projector, and is widely used as a device capable of enlarging an image of a personal computer or a television and projecting it on a screen.

The projection type liquid crystal display device includes: the form of directly amplifying the split beam from the color filter with a single plate, the form of making the beam split into three primary colors pass through the corresponding transmissive liquid crystal cell, and the beam split into three primary colors Each is reflected by a reflective liquid crystal cell, etc. Here, the structure of a projection type liquid crystal display device using a transmissive type liquid crystal cell corresponding to three primary colors, which is currently in the mainstream, will be described with reference to FIG. 6 .

Such a projection type liquid crystal display device is usually equipped with a light source system, reflection, light splitting system and magnifying projection system. The light source system has a white light source 11 and an ultraviolet/infrared cut filter 13. The white light L from the white light source is filtered by the ultraviolet/infrared cut filter 13 to remove ultraviolet rays and infrared rays, and is sent to the first spectroscope 1. As the white light source 11, metal halide lamps and high-pressure mercury lamps are generally used.

There are four kinds of beam splitters 1, 2, 3, 4 in the reflection and light splitting system, two total reflection mirrors 5, 6, liquid crystal cells 7R, 7R, 7G and 7B, incident-side polarization conversion elements 8R, 8G, and 8B, exit-side polarization conversion elements 9R, 9G, and 9B, and condenser lenses 10R, 10G, and 10B.

The first beam splitter 1 only transmits green light G and blue light, and sends the green light G and blue light B to the second beam splitter 2 . The red light R reflected by the first dichroic mirror 1 is sent to the first total reflection mirror 5, where it is reflected and passes through the condenser lens 10R for red light, the incident side polarization conversion element 8R, the liquid crystal cell 7R and the exit side polarized light The conversion element 9R is sent to the third dichroic mirror 3 . On the other hand, the second dichroic mirror 2 only transmits the blue light B, and among the green light G and the blue light B that pass through the first dichroic mirror 1, the blue light B that passes through the second dichroic mirror 2 passes through the blue light concentrator. The optical lens 10B, the incident-side polarization conversion element 8B, the liquid crystal cell 7B, and the exit-side polarization conversion element 9B are sent to the second total reflection mirror 6 . In addition, the green light G reflected by the second dichroic mirror 2 is sent to the third dichroic mirror 3 through the green light condensing lens 10G, the incident-side polarization conversion element 8G, the liquid crystal cell 7G, and the exit-side polarization conversion element 9G. The 3rd dichroic mirror 3 only passes through red light, the red light that passes through red light with condenser lens 10R, incident side polarization conversion element 8R, liquid crystal cell 7R and exit side polarization conversion element 9R from the first total reflection mirror 5, does not add In addition, from the second beam splitter 2, the green light G that passes through the condenser lens 10G for green light, the incident side polarization conversion element 8G, the liquid crystal cell 7G and the exit side polarization conversion element 9G is transmitted by the second beam splitter 2 The three beam splitters 3 reflect and are sent to the fourth beam splitter 4 respectively. The fourth beam splitter 4 only passes the red light R and the green light G, it allows the red light R and the green light G from the third beam splitter 3 to pass through unchanged, and the blue light B from the second total reflection mirror 6 It is reflected here and sent to the projection lens 16 respectively.

In addition, here, a form in which red light is first split, and then green light and blue light are split, is shown here, but the order of splitting can be changed arbitrarily by combining the splitters.

The magnification projection system includes a projection lens 16 which magnifies images corresponding to respective lights and projects the magnified images onto a screen 17 . Furthermore, incident side polarization conversion elements 8R, 8G, 8B and output side polarization conversion elements 9R, 9G, 9B of the liquid crystal cells 7R, 7G, 7B corresponding to the respective colors of light are sometimes pasted on the liquid crystal cells 7R, 7G, 7B for use. , and are usually spaced apart from the liquid crystal cells 7R, 7G, and 7B, and this space constitutes an air passage for cooling. In addition, the incidence-side polarization conversion elements 8R, 8G, and 8B are also separated from the condenser lenses 10R, 10G, and 10B. In this way, when the polarization conversion elements 8R, 8G, 8B, 9R, 9G, and 9B are arranged at intervals from the liquid crystal cells 7R, 7G, and 7B and the condenser lenses 10R, 10G, and 10B, stick a linear polarizer on glass, etc. Reinforcement material is used on the form.

In such a projection-type liquid crystal display device, each liquid crystal cell 7R, 7G, 7B is arranged between two polarization conversion elements, that is, between the input-side polarization conversion elements 8R, 8G, 8B and the output-side polarization conversion elements. Between elements 9R, 9G, 9B. These polarization conversion elements 8 and 9 generate a large amount of heat because they transmit the amount of light required to magnify the image and project it on the screen. In addition, when the red light R, the green light G and/or the blue light B are polarized light, it is often necessary to rotate the plane of polarization when entering the liquid crystal cells 7R, 7G, and 7B. In addition, the polarized light emitted from the liquid crystal cells 7R, 7G, and 7B may also rotate the plane of polarization again.

In order to rotate the plane of polarization, a phase difference plate can be used, and the phase difference plate is usually arranged on the light source 11 side of the incident side polarization conversion elements 8R, 8G, 8B and the projection lens 16 side of the output polarization conversion elements 9R, 9G, 9B . As the retardation plate, a retardation plate made of resin is used in view of factors such as availability and price. This retardation plate is used in the form of being attached to a linear polarizer on the incident-side polarization conversion elements 8R, 8G, and 8B or the output-side polarization conversion elements 9R, 9G, and 9B.

Due to the influence of the birefringence of the liquid crystal cell in such a projection type liquid crystal display device, there is a problem that the so-called contrast of the image projected on the screen is not high.

Therefore, Japanese Unexamined Patent Application Publication No. 2000-137202 (Patent Document 1) proposes to use an optical compensation layer for a projection type liquid crystal display device to moderate the contrast and luminance variation of image in-plane distribution in image components. In addition, in Japanese Patent Application Laid-Open No. 2000-352615 (Patent Document 2), it is suggested that a polarizing plate be pasted on glass with a small absolute value of the average linear expansion coefficient, and that it be used as the incident-side or outgoing-side polarized light of a projection-type liquid crystal display device. It is also suggested that an optically anisotropic body other than the liquid crystal cell be arranged between the incident-side polarization conversion element and the exit-side polarization conversion element at a position away from any polarizing plate. These optical compensation layers or optical anisotropic materials are used for hybrid alignment of discotic liquid crystals, for example, those disclosed in JP-A-8-50206 (Patent Document 3). In the structures specifically disclosed in Patent Document 1 and Patent Document 2, an optical compensation layer or an optical anisotropic body is disposed on both sides of the front and rear sides of the liquid crystal cell, and a polarizing plate is disposed on each outer side. On the other hand, in JP-A-2002-14345 (Patent Document 4), it is proposed to provide an optical compensation layer on the light exit side of the liquid crystal cell to optically compensate the liquid crystal molecules present in the light incident side region of the liquid crystal layer, It has also been proposed to superimpose two or three such optical compensation layers. However, the optical compensation and optical anisotropic bodies disclosed in Patent Document 1, Patent Document 2, and Patent Document 4 all have the problem that the characteristics against ultraviolet light are easily deteriorated and their reliability is poor.

[Patent Document 1] JP-A-2000-137202

[Patent Document 2] JP-A-2000-352615

[Patent Document 3] JP-A-8-50206

[Patent Document 4] JP-A-2002-14345

Contents of the invention

The inventors of the present invention have conducted studies to develop an optical compensation plate capable of improving the contrast of a projection-type liquid crystal display device and realizing continuous high-quality display for a long period of time. As a result, a transparent film with specific transmission and reflection characteristics is used, and it is laminated on a transparent glass plate with a liquid crystal compound coated on the substrate film to form an optical compensation film. Through such a structure, it is possible to improve Contrast, maintain high-quality images for a long time.

That is, the optical compensation plate of the present invention is formed by laminating the following parts: a transparent film having a transmittance of 10% or less at a wavelength of 380nm and a reflectance of 2% or less at a wavelength of 550nm on the surface in contact with air sheet; an optical compensation film composed of a liquid crystal compound coated on the substrate film; and a transparent glass plate.

The optical compensation plate is used to be assembled into a projection type liquid crystal display device. Therefore, the present invention also provides a projection type liquid crystal display device configured by arranging the above-mentioned optical compensation plate on at least one side of the liquid crystal cell. More specifically, the projection type liquid crystal display device is provided with: a white light source; an optical system of a color separation coating for splitting the white light from the white light source into three primary colors of red light, green light and blue light; a box; a polarization conversion element; and the aforementioned optical compensation plate. The optical system in this case includes, for example, a beam splitter for splitting white light from a white light source into three primary colors of red light, green light, and blue light, a total reflection mirror, and a condenser lens.

Description of drawings

Fig. 1 is a schematic sectional view showing an example of an optical compensation plate of the present invention.

Fig. 2 is a schematic sectional view showing another example of an optical compensation plate of the present invention.

Fig. 3 is an arrangement diagram showing an example of the axis-angle relationship when a transparent film and two optical compensation films are laminated in the optical compensation plate of the present invention.

4 is a layout diagram showing another example of the axis-angle relationship when a transparent film and two optical compensation films are laminated in the optical compensation plate of the present invention.

5 is a layout diagram showing still another example of the axis-angle relationship when a transparent film and two optical compensation films are laminated in the optical compensation plate of the present invention.

6 is an explanatory diagram schematically showing a configuration example of a projection type liquid crystal display device.

7 is a schematic cross-sectional view showing an arrangement example when the optical compensation plate of the present invention is combined with a liquid crystal cell to form a projection type liquid crystal display device.

[explanation of the symbol]

1, 2, 3, 4...beam splitter,

5, 6... total reflection mirror,

7, 7R, 7G, 7B...LCD box,

8, 8R, 8G, 8B... Polarization conversion element on the incident side,

9, 9R, 9G, 9B... Polarization conversion elements on the exit side,

10R, 10G, 10B...condensing lens,

L...White light (light source light),

R...red light,

G...green light,

B...blue light,

11......white light source,

13......UV/IR cut filter,

16...projection lens,

17...screen,

20......Optical compensation plate,

21......transparent diaphragm,

23... glass plate,

27...An anti-reflection layer arranged on the transparent diaphragm,

28...Anti-reflection layer on the side of the glass plate,

30, 40... Optical compensation film,

31, 41... The substrate diaphragm of the optical compensation diaphragm,

32, 42...the liquid crystal compound layer of the optical compensation film.

Detailed ways

The present invention will be described in detail below. In the present invention, a transparent film having a specific ultraviolet absorption characteristic and having a low reflectance on a surface in contact with air is used. The transparent film used here is made of resin, for example, polycarbonate series resins such as modified polycarbonate having a fluorene skeleton and general polycarbonate obtained from bisphenol A, diacetyl cellulose and triacetyl cellulose. Cellulose series resins such as acetyl cellulose, polysulfone series resins, polyethersulfone series resins, polyester series resins, polyimide series resins, polyamide series resins, polyarylate series resins, etc., this transparent film The thickness is usually about 10-1000 μm, preferably more than 10 μm and less than 200 μm.

Also, in the present invention, a transparent film having a transmittance at 380 nm of 10% or less is used as such a transparent film. It is more desirable to use one with a transmittance of 5% or less at a wavelength of 380 nm. Such characteristics can be achieved by including so-called ultraviolet absorbers such as benzotriazole-based, benzoate-based, benzophenone-based, salicylate-based, nickel complex-based, etc. in the film. In order to make the film contain an ultraviolet absorber, a well-known common method can be used, for example, the method of adding an ultraviolet absorber to the resin impregnated liquid for forming the film to form a film, and dissolving the ultraviolet absorber A method in which a solution of an ultraviolet absorber is applied to a transparent film and dried. The content of the ultraviolet absorber is preferably, for example, about 0.01 to 10 parts by weight relative to 100 parts by weight of the resin. It is also possible to use a commercially available transparent film containing an ultraviolet absorber, and an example of a commercially available film meeting such a requirement has triacetyl cellulose (TAC cellulose) containing an ultraviolet absorber sold by Fuji Photo Film Co., Ltd. ) film (product name with "UZ" and "TD" and "TDY") (thickness 100μm, 80μm, 50μm, 40μm, etc.) and triacetyl with UV absorber sold by Konica Co., Ltd. Cellulose (TAC) film (products with "UX2M" in the product name) (thickness 80μm, 57μm, 40μm, etc.), etc.

In addition, this transparent film is laminated with an optical compensation film and a glass plate to be described later, so that the transparent film becomes the outer surface of one side, and the reflectance at a wavelength of 550 nm of the transparent film is 2 %the following. The reflectance is ideally 1% or less, preferably 0.5% or less. Such properties can be achieved by providing an anti-reflection layer on the surface. The antireflection layer is a layer that reduces reflected light at the interface in contact with the air layer, and prevents the occurrence of stray light caused by such reflected light. As the antireflection layer, generally used materials may be, for example, single-layer or multi-layer structures composed of compounds selected from metals, metal oxides, and metal fluorides. The metal may be silver or the like, the metal oxide may be, for example, silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, yttrium oxide, or zirconium oxide, and the metal fluoride may be, for example, magnesium fluoride. The antireflection layer may be a single layer, or may be a multilayer of 2, 3, or 4 or more layers. The thickness of the antireflection layer and the thickness of each layer in the case of multiple layers can be appropriately selected according to the number of layers, the refractive index of the material used for each layer, and the like. In addition, in order to improve the adhesion between the antireflection film and the transparent film, an acrylic coating layer and a hard coating layer may be provided between them.

On the surface of the transparent film with the antireflection layer, the contact angle is preferably 80° or more, more preferably 100° or more. The contact angle referred to here is a value when a liquid such as water is used. When the contact angle on the surface in contact with the air is less than 80°, particles are easy to adhere, and a projection type liquid crystal display device using an optical compensation plate with such a surface tends to have a tendency to decrease contrast when it is used continuously for a long time . The upper limit of the contact angle is 180°.

When the surface of the anti-reflection layer satisfies the contact angle specified here, a transparent film having such an anti-reflection layer can be used in the present invention as it is, for example, "HT" manufactured by "Toppan Printing Co., Ltd." can be used. -ARPSMC", etc. In addition, in the case where there are many antireflection layers, since there is no contact angle specified here, the above contact angle can be realized by providing a layer made of fluoride on the antireflection layer. A layer composed of fluoride can be provided by applying a coating liquid containing the compound to the surface. For this reason, the fluorine compound used is not particularly specified if the contact angle of the surface can be more than 80°; the material commonly used to prevent surface contamination, for example, can be a material such as a fluorine-containing silane compound. Such fluorides have been widely used in coatings and the like because they can prevent the adhesion of dirt such as fingerprints on the surface.

In the present invention, a transparent film having such a specific optical transmittance and a specific surface reflectance is used in combination with a specific optical compensation film. The optical compensation film is formed by coating liquid crystal compound on the surface of the substrate film and aligning it. After the film is assembled on the projection type liquid crystal display device, it compensates for the liquid crystal molecules in the liquid crystal cell. Optical phase difference.

As the base film of the optical compensation film, there are, for example, polycarbonate series resins such as modified polycarbonate having a fluorene skeleton and general polycarbonate obtained from bisphenol, diacetyl cellulose and triacetyl cellulose Cellulose-based resins such as cellulose, cyclopolyolefin-based resins that are polymers of norbornene-based monomers, polysulfone-based resins, polyethersulfone-based resins, polyester-based resins, polyimide-based resins, polyamides series resins, polyarylate series resins, etc. The thickness of this base film is usually about 10 to 1000 μm. The liquid crystal compound coated thereon may be, for example, a discotic liquid crystal compound having a triphenylene skeleton, a polymer liquid crystal compound, and the like. The method for aligning the liquid crystalline compound can be a common method, for example, the surface of the substrate film can be pre-aligned, the liquid crystalline compound is coated on it, and after drying, the liquid crystalline compound can be formed by heat treatment. Orientation fixation methods, etc. Such an optical compensation film coated with an alignment liquid crystalline compound is described, for example, in the aforementioned Patent Document 3. As a commercially available optical compensation film after coating an alignment liquid crystal compound, for example: "Wide-view film" (sometimes also called "WV film") sold by Fuji Photo Film Co., Ltd. (type: WV A 03B, WV A 12B, WV A 038, WV A 128) and NISCO LC Diaphragms, NISCO NH Diaphragms, and NISCO NR Diaphragms sold by NISCO Mitsubishi Co., Ltd.

In the present invention, the above-described transparent film and optical compensation film are pasted on a transparent glass plate to form an optical compensation plate. As the transparent glass plate, common silicon-based glass plates called blue plate glass and white plate glass, quartz glass, and the like can be used. In addition, it is also suitable to use sapphire glass and crystal glass with high thermal conductivity. The sapphire glass is a single crystal of aluminum oxide (AI ₂ O ₃ ), and for example, one formed into a plate by the EFG method (EdGe-defined Film-fed Growth method) is used. Crystal glass is a single crystal of _SiO2 , which can be a synthetic crystal or a natural crystal. It is preferable to provide an antireflection layer on one side surface of the transparent glass plate, that is, the exposed surface. The thickness of the transparent glass plate is usually about 0.1 to 2 mm, preferably 0.3 mm or more, and more preferably 0.8 mm or less. The area of the transparent glass plate can be appropriately selected according to the size of the projection-type liquid crystal display device to be produced. Typical examples include a rectangle or square with a side length of 10 to 100 mm, a circle or an ellipse with a diameter of 5 to 100 mm, and the like.

A transparent film and an optical compensation film are laminated on such a transparent glass plate. At this time, a transparent film is formed on one outer surface, and usually laminated in the order of transparent glass plate/optical compensation film/transparent film. The area of the transparent film and the optical compensation film is generally about the same as that of the transparent glass plate or slightly smaller than that of the glass plate. It is easy to paste on the glass surface if the area is small. It is better to reduce the area of the transparent film and the optical compensation film so that it is pasted on the inner side of about 0.5-5mm from the edge of the transparent glass plate.

The transparent film and the optical compensation film as well as the glass plate and the optical compensation film are usually laminated by an adhesive layer. As the adhesive constituting the adhesive layer, pressure-sensitive adhesives such as acrylic-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and the like are used. Pressure sensitive adhesives generally provide transparent optically isotropic adhesive layers. In addition, pressure-sensitive adhesives are collectively referred to as adhesives. The thickness of the adhesive layer is usually about 10 to 60 μm.

In the optical compensation plate of the present invention, two optical compensation plates in which a liquid crystal compound is coated on a base film are preferably stacked adjacent to each other. That is to say, the two optical compensation films are positioned on the surface of the glass plate side, if the order of the transparent film/the first optical compensation film/the second optical compensation film with anti-reflection layer is arranged, the transparent film will be If the anti-reflection layer is on the outermost side, the contrast improvement effect will be higher. At this time, the respective orientation axes of the two optical compensation films are preferably disposed approximately perpendicularly intersecting. In addition, the so-called "approximately perpendicularly intersecting" here is preferably perpendicularly intersecting (90°), and the deviation within the range of ±5° is allowable. of. "Approximately" used in other parts of this specification when referring to angular configurations also has the same meaning. Furthermore, among the two optical compensation films, when the first optical compensation film close to the transparent film is assembled into a projection type liquid crystal display device, its orientation axis is preferably aligned with the linearly polarized light in the adjacently arranged polarization conversion element. The absorption axes of the plates intersect substantially perpendicularly or are arranged substantially in parallel. In addition, the two optical compensation films are preferably arranged such that the opposite side, that is, the side of the substrate film, overlaps with the side on which the liquid crystal compound is applied.

1 and 2 show examples of the optical compensation plate of the present invention. In the example shown in FIG. 1 , the transparent film 21 and the optical compensation film 30 are laminated, and the optical compensation film 30 is pasted on the glass plate 23 to form the optical compensation plate 20 . Here, the optical compensation film 30 is formed after coating the liquid crystal compound layer 32 on the substrate film 31 and aligning it. One side of the liquid crystal compound layer 32 is pasted on the transparent film 21. The base film 31 One example is pasted on the glass plate 23. An anti-reflection layer 27 is provided on the side of the transparent film in contact with the air. In addition, an antireflection layer 28 is provided on the outer surface of the glass plate 23 opposite to the bonding surface of the optical compensation film 30 . When the glass plate 23 has optical anisotropy, it is necessary to make its crystal axis parallel or perpendicular to the polarization axis of the transmitted polarized light. For example, when the glass plate 23 is sapphire glass, the C axis of the sapphire glass and the The polarization axes of the transmitted polarized light are arranged to intersect substantially parallel or substantially perpendicularly.

The example shown in FIG. 2 is: on the basis of the layer structure in FIG. 1 , a second optical compensation film 40 is added between the optical compensation film 30 and the glass plate 23 as the structure of the optical compensation plate 20 . Therefore, the optical compensation film 30 disposed on the side of the transparent film 21 is used as the first optical compensation film. The second optical compensation film 40 is also formed by coating the alignment liquid crystal compound layer 42 on the base film 41 . In the example shown in FIG. 2 , the two optical compensation films 30 and 40 are arranged so that their respective orientation axes intersect substantially perpendicularly. These two optical compensation films are arranged to overlap each other on the side opposite to the coated surface of the liquid crystal compound layers 32 and 42 , that is, on the side of the substrate film 31 and 41 .

3 to 5 show the relationship between the axis angles of the two optical compensation films 30 and 40 in the case of laminating the optical compensation films 30 and 40 as shown in FIG. 2 in two layers. Both represent the relationship between the axis angles when two optical compensation films, ie, the first optical compensation film 30 and the second optical compensation film 40 are laminated in this order on one side of the transparent film 21 . In any case, the orientation axis of the first optical compensation film 30 and the orientation axis of the second optical compensation film 40 are arranged to intersect substantially perpendicularly. That is, if the right direction of the long sides of the respective optical compensation films 30, 40 is taken as 0°, then in Fig. 3, the orientation axis of the first optical compensation film 30 is taken as the direction of 135 °, The orientation axis of the compensation film 40 is taken as the direction of 225 °. In Fig. 4 and Fig. 5, the orientation axis of the first optical compensation film 30 is taken as the direction of 270 °, and the orientation axis of the second optical compensation film 40 is taken as 180° direction or 0° direction. Furthermore, in FIG. 4 and FIG. 5 , the direction of the arrow representing the orientation axis of the second optical compensation film 40 is opposite, and the direction of this arrow means the rubbing direction of the orientation.

The optical compensation plate of the present invention can be applied to a projection type liquid crystal display device. For example, in a projection-type liquid crystal display device, it can be inserted into the optical path of white light from a white light source, or used in the optical path of each primary color light of red light, green light, or blue light after splitting white light.

Specifically, in the projection-type liquid crystal display device shown in FIG. 6, it can be arranged between the liquid crystal cells 7R, 7G, 7B corresponding to the three primary colors and the incident side polarization conversion elements 8R, 8G, 8B, or the output side polarized light The conversion elements 9R, 9G, and 9B are used between the liquid crystal cells 7R, 7G, and 7B. Arranged at all intervals between incident-side polarization conversion elements 8R, 8G, 8B and liquid crystal cells 7R, 7G, 7B or at all intervals between output-side polarization conversion elements 9R, 9G, 9B and liquid crystal cells 7R, 7G, 7B The optical compensation plate of the present invention is even more effective. The optical compensation plate is usually configured so that the glass plate 23 shown in Fig. 1 and Fig. 2 is on the side of the polarization conversion element 8R, 8G, 8B or 9R, 9G, 9B. 23 is closer to the side of the liquid crystal cell 7R, 7G, 7B.

An example of arrangement in such a projection type liquid crystal display device is shown in FIG. 7 in a schematic cross-sectional view. Fig. 7 (A) is the example that the optical compensation plate 20 shown in Fig. 1 is disposed between the liquid crystal cell 7 and the polarization conversion element 8 or 9 on the incident side or the outgoing side, in addition, Fig. 7 (B) is the The illustrated example is an example in which the optical compensation plate 20 is arranged between the liquid crystal cell 7 and the polarization conversion element 8 or 9 on the incident side or the output side. In either case, the transparent film 21 constituting the optical compensation plate 20 is arranged on the side of the liquid crystal cell, and the glass plate 23 is arranged on the side of the polarization conversion element 8 or 9 . In addition (not shown), the polarization conversion element 8 or 9 may be attached to the glass surface opposite to the surface on which the optical compensation film 30 or 40 of the optical compensation plate is attached. Furthermore, on the surface opposite to the surface of the optical compensation film 30 or 40 pasted with the optical compensation plate, a polarizing plate can also be directly pasted as a polarization conversion element. At this time, not only the number of parts is reduced, the cost is reduced, but also the Air supply to improve cooling efficiency. In addition, especially for the polarization conversion element on the output side, for the purpose of protecting the polarizing plate disposed there, a polarizing plate (pre-polarizing plate) with a high transmittance can be pasted on the surface to which the optical compensation plate is pasted. On the opposite glass plate surface of the optical compensation film 30 or 40, a common polarizing plate (main polarizing plate) is pasted on its outside so that its transmission axis is parallel to the transmission axis of the previous pre-polarizing plate, as polarized light. Transform element. At this time, since light is absorbed to some extent by the polarizer (pre-polarizer) with high transmittance, the absorption of light by the main polarizer arranged behind it can be softened. Examples of high-transmittance polarizing plates used for such purposes include "STX8C2A-HC-AR", "STX8B2A=HC-AR", and "STX8A2A-HC-OB" sold by Sumitomo Chemical Industries, Ltd.

On the other hand, there is also a projection type liquid crystal display device that directly amplifies the split beam from the color filter in the form of a single plate, and in this case, in the optical path of white light, before or before the liquid crystal cell containing the color filter Then configure the optical compensation plate of the present invention.

[Example]

The present invention will be described in more detail with specific examples below, but the present invention is not limited by these examples.

Example 1

The transmittance at a wavelength of 380nm is 2.4% in combination with an ultraviolet absorber. In addition, anti-reflection treatment is applied to one side, and a triacetyl cellulose film with a surface reflectance of 0.5% at a wavelength of 550nm is used as a transparent Diaphragm. On the side opposite to the anti-reflection treatment surface, there is an optical compensation film coated with an alignment liquid crystal compound on the substrate film, and two "wide-view film WV" sold by Fuji Photo Film Co., Ltd. A 03B" are laminated by adhesive respectively. At this time, the two optical compensation films are arranged at the same axis angle as shown in FIG. 5 , and are bonded face-to-face with the surface of the base film opposite to the surface on which the respective liquid crystal compound layers are formed. Anti-reflection treatment is applied to one side of a sapphire glass plate with a diagonal size of 0.9 inches (about 23mm) sold by Jingsera Co., Ltd., and the above-mentioned transparent film/second The laminated body of an optical compensation film/second optical compensation film is bonded on the liquid crystal compound side of the second optical compensation film to produce an optical compensation plate with the structure shown in FIG. 2 . At this time, the orientation axis of the second optical compensation film 40 is bonded to coincide with the C-axis of the sapphire 23 .

If the red (R), green (G) and blue (B) liquid crystal cells of the projection type liquid crystal display device are set and the optical compensation plate obtained above is set between each output side polarization conversion element, the glass plate is placed On the side of the polarization conversion element, the contrast on the screen is improved, and the high display quality can be maintained continuously for a long time.

Comparative example 1

An optical compensation plate was fabricated in the same manner as in Example 1 except that no transparent film was used. When this optical compensation plate was installed in a projection-type liquid crystal display device in the same manner as in Example 1, the contrast on the screen was improved, but the display quality deteriorated when used for a long time.

[Effect of the invention]

The optical compensation plate of the present invention is an optical compensation plate in which a specific transparent film having an anti-reflection layer and an optical compensation film are arranged in a specific order, and is effectively used in a projection type liquid crystal display device. The projection-type liquid crystal display device of the panel improves the contrast of the projected image, and maintains high-quality display continuously for a long time.

Claims (8)

1. optical compensation plate, it is characterized in that: it by in wavelength 380nm place transmitance be below 10%, with face that air contacts on the reflectivity at wavelength 550nm place be transparent membrane below 2%, the optical compensation diaphragm that the coated with liquid crystal compound forms on the base material diaphragm, and transparency glass plate is laminated.

2. optical compensation plate as claimed in claim 1 is characterized in that: it forms by the optical compensation membrane layer that has applied liquid crystal compounds on two its base material diaphragms is folded.

3. optical compensation plate as claimed in claim 2 is characterized in that: two optical compensation diaphragms, axis of orientation approximate vertical separately disposes crossingly.

4. optical compensation plate as claimed in claim 2 is characterized in that: form the unilateral mutual applying of its base material film relative with the liquid crystal compounds applicator surface by two optical compensation membrane layers are folded.

5. optical compensation plate as claimed in claim 3 is characterized in that: form the unilateral mutual applying of its base material film relative with the liquid crystal compounds applicator surface by two optical compensation membrane layers are folded.

6. as each described optical compensation plate in the claim 1～5, it is characterized in that: transparency glass plate is a sapphire glass.

7. a projection-type liquid crystal display device is characterized in that: a side that is configured in liquid crystal cell as each described optical compensation plate in the claim 1～5.

8. projection-type liquid crystal display device, it is characterized in that: optical compensation plate as claimed in claim 6 is configured in a side of liquid crystal cell.

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