KR101008243B1 - Optical compensation plate and project type liquid crystal display device using the same - Google Patents

Abstract

(Problem) The contrast of a projection type liquid crystal display device is increased, and color deviation in black display does not occur well even if used for a long time, so that an optical compensation plate capable of realizing high display quality is provided and applied to the projection type liquid crystal display device.

(Solution means) The liquid crystal compound layer 32 is applied to the transparent film 21 and the base film 31 having a photoelastic coefficient of 7 × 10 ⁻¹³ cm 2 / dyne or less and the antireflection layer 27 is formed on the surface thereof. The optical compensation film 20, which is made of the optical compensation film 30 and the transparent glass plate 23, is laminated with the antireflection layer 27 of the transparent film at the outermost side. Two optical compensation films 30 and 40 may be laminated, in which case each alignment axis is substantially orthogonal, and the base film 31 and 41 faces opposite to the surface on which the liquid crystal compound is applied are overlapped. Are stacked. The optical compensation plate 20 is arranged such that the transparent film 21 is on the side of the liquid crystal cell 7 to form a projection type liquid crystal display device.

Optical compensation plate, projection type liquid crystal display device

Description

Optical Compensation Plate and Projection Type Liquid Crystal Display Using It {OPTICAL COMPENSATION PLATE AND PROJECT TYPE LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME}

BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic diagram which shows an example of the optical compensation plate which concerns on this invention.

2 is a schematic cross-sectional view showing another example of the optical compensation plate according to the present invention.

Fig. 3 is a layout view showing an example of the relationship between the axial angles when laminating a transparent film and two optical compensation films in the optical compensation plate according to the present invention.

Fig. 4 is a layout view showing another example of the relationship between the axial angles in the case of laminating a transparent film and two optical compensation films in the optical compensation plate according to the present invention.

5 is a layout view showing another example of the relationship between the axial angle in the case of arranging the transparent film and the two optical compensation films in the optical compensation plate according to the present invention.

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

Fig. 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 main parts of drawing

1, 2, 3, 4: dichroic mirror
5, 6: total reflection mirror

7, 7R, 7G, 7B: liquid crystal cell
8, 8R, 8G, 8B: incident side polarization conversion element

9, 9R, 9G, 9B: emission side polarization conversion element
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 film

23: glass plate 27: antireflection layer formed on the transparent film

28: glass plate side antireflection layer 30, 40: optical compensation film

31, 41: base film of the optical compensation film

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

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 the same.

Projection type liquid crystal display devices, also called liquid crystal projectors, are widely used as devices capable of enlarging a screen such as a personal computer, a television, or the like onto a screen.

Projection type liquid crystal display devices are of a single plate type, in which the spectral light from the color filter is directly enlarged, spectroscopically in three primary colors, and then passed through a transmissive liquid crystal cell corresponding to each light; And a type of reflection by a reflective liquid crystal cell corresponding to light. Here, the outline of the configuration will be described with reference to FIG. 6 for the projection type liquid crystal display device using the transmissive liquid crystal cell corresponding to the three primary colors which are currently mainstream.

Such a projection liquid crystal display device is usually provided with a light source system, a reflection spectrometer, and an enlarged projection system. The light source system includes a white light source 11 and a UV / IR cut filter 13, and the white light L from the white light source 11 is cut by ultraviolet and infrared rays by the UV / IR cut filter 13. It is intended to be sent to the first dichroic mirror 1. As the white light source 11, a metal halide lamp, a high pressure mercury lamp, or the like is usually used.

The reflecting and spectrophotometer includes four types of dichroic mirrors 1, 2, 3, and 4, two total reflection mirrors 5 and 6, and liquid crystals corresponding to red light (R), green light (G), and blue light (B), respectively. Cells 7R, 7G and 7B, incident side polarization conversion elements 8R, 8G and 8B, exit side polarization conversion elements 9R, 9G and 9B and condensing lenses 10R, 10G and 10B are provided.

The first dichroic mirror 1 transmits only the green light G and the blue light B, and the green light G and the blue light B transmitted therethrough are transferred to the second dichroic mirror 2. Is sent. 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 then the red condenser lens 10R, the incident side polarization conversion element 8R, It passes through the liquid crystal cell 7R and the emission side polarization conversion element 9R, and is sent to the 3rd dichroic mirror 3. On the other hand, the second dichroic mirror 2 transmits only the blue light B, and the second dichroic mirror 2 of the green light G and the blue light B transmitted through the first dichroic mirror 1 The blue light B transmitted through 2) passes through the blue condensing lens 10B, the incident side polarization converting element 8B, the liquid crystal cell 7B, and the exit side polarization converting element 9B and passes through the second total reflection mirror 6 Sent to). Further, the green light G reflected by the second dichroic mirror 2 is the green condenser lens 10G, the incident side polarization conversion element 8G, the liquid crystal cell 7G and the exit side polarization conversion element 9G. Is sent to the third dichroic mirror (3). The third dichroic mirror 3 transmits only the red light R. From the first total reflection mirror 5, the red condenser lens 10R, the incident side polarization conversion element 8R, the liquid crystal cell 7R, The red light R which has passed through the exit-side polarization conversion element 9R passes through the third dichroic mirror 3 as it is, and the green condenser lens 10G enters from the second dichroic mirror 2. The green light G passing through the side polarization converting element 8G, the liquid crystal cell 7G, and the exit side polarization converting element 9G is reflected by the third dichroic mirror 3 and is respectively the fourth dichroic mirror. Is sent to (4). The fourth dichroic mirror 4 transmits only red light (R) and green light (G), and the red light (R) and green light (G) from the third dichroic mirror (3) pass through as it is. The blue light B from the second total reflection mirror 6 is reflected here and sent to the projection lens 16, respectively.

In this case, the red light R is first spectroscopy, and then the green light G and blue light B are spectroscopy. However, the combination of the dichroic mirrors can be used to change the order of the spectra.

The magnification projection system includes a projection lens 16, in which an image corresponding to each light is magnified to project an magnified image on the screen 17. FIG. Incidentally, the incident-side polarization conversion elements 8R, 8G and 8B and the exit-side polarization conversion elements 9R, 9G and 9B of the liquid crystal cells 7R, 7G and 7B corresponding to the respective colors are formed in the liquid crystal cells 7R, 7G and Although it may be used to adhere to 7B), it is usually arranged at intervals with the liquid crystal cells 7R, 7G, and 7B, and the interval is a cooling ventilation path. Incidentally, the incidence-side polarization conversion elements 8R, 8G, and 8B are also spaced apart from the condensing lenses 10R, 10G, and 10B. As described above, when the polarization conversion elements 8R, 8G, 8B, 9R, 9G, and 9B are disposed apart from the liquid crystal cells 7R, 7G, and 7B and the condensing lenses 10R, 10G, and 10B, the linear polarizer is glass. It is used in the form adhered to reinforcing materials such as.

In such a projection type liquid crystal display device, each of the liquid crystal cells 7R, 7G, and 7B has two polarization conversion elements, namely, the incident side polarization conversion elements 8R, 8G, and 8B, and the emission side polarization conversion elements 9R, 9G, and the like. 9B). These polarization conversion elements 8 and 9 generate a large amount of heat because light of a quantity of light necessary for enlarging and projecting an image on the screen is transmitted. 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 polarization plane when incident on the liquid crystal cells 7R, 7G, and 7B. In addition, the polarized light emitted from the liquid crystal cells 7R, 7G, and 7B may rotate the polarization plane again.

In order to rotate the polarization plane, a phase difference plate may be used, and the phase difference plate is usually projected by the light source 11 side or the emission side polarization conversion elements 9R, 9G, and 9B of the incident side polarization conversion elements 8R, 8G, and 8B. It is arranged on the lens 16 side. As the retardation plate, one made of resin is usually used in view of availability and price. This retardation plate is used in the form adhered to the linear polarizing plate in the incident side polarization conversion elements 8R, 8G and 8B or the exit side polarization conversion elements 9R, 9G and 9B.                         

Such a projection type liquid crystal display device has a problem that the contrast of an image projected on the screen is not high due to the birefringence effect of the liquid crystal cell.

Therefore, Japanese Unexamined Patent Application Publication No. 2000-137202 (Patent Document 1) proposes to alleviate the contrast and brightness bias of the in-plane distribution of image components in a projection liquid crystal display device by an optical compensation layer. Further, Japanese Patent Application Laid-Open No. 2000-352615 (Patent Document 2) proposes that a polarizing plate is adhered to glass having a small absolute value of the average line expansion coefficient, and that the polarizing plate is used for the incident side or the exit side polarization conversion element of the projection type liquid crystal display device. In addition, it has also been proposed to arrange optically anisotropic bodies other than liquid crystal cells at positions away from all polarizing plates between the incident side polarization conversion element and the exit side polarization conversion element. As these optical compensation layers or optically anisotropic bodies, those in which a discotic liquid crystal is hybrid-oriented, such as those disclosed in JP-A-8-50206 (Patent Document 3) can be mentioned. The structure specifically disclosed by these patent documents 1 and patent documents 2 arrange | positions an optical compensation layer or an optically anisotropic body one each on the front and back sides of a liquid crystal cell, and arrange | positions one polarizing plate further on each outer side. On the other hand, Japanese Patent Application Laid-Open No. 2002-14345 (Patent Document 4) discloses an optical compensation layer formed on the light exit side of a liquid crystal cell and performing optical compensation on liquid crystal molecules present in the incident side region of light in the liquid crystal layer. It has been proposed, and overlapping two or three of the optical compensation layer is also proposed. However, the projection type liquid crystal display device using the optical compensation layer or optically anisotropic body disclosed in these patent documents 1, patent documents 2, and patent documents 3 had a problem that the color deviation in black display was outstanding.

The present inventors have conducted research to develop an optical compensation plate that can make the contrast of a projection type liquid crystal display device higher, and that color deviation in black display does not occur well even if used for a long time, and that high display quality can be realized for a long time. come. As a result, the photoelastic coefficient is small, and a transparent film having an antireflection layer on a surface in contact with air, an optical compensation film formed by applying a liquid crystalline compound to a base film, and a transparent glass plate are laminated so that the image projected on the screen It has been found that no color deviation occurs in the black display, so that high quality image display can be maintained for a long time, and the present invention has been reached.

Means to solve the problem

That is, the optical compensating plate of the present invention has a photoelastic coefficient of 7 × 10 ⁻¹³ cm 2 / dyne or less, an optical compensation film formed by applying a liquid crystal compound to a base film, and a transparent film having an antireflection layer formed on a surface thereof. The glass plate is laminated so that the antireflection layer of the transparent film is the outermost.

This optical compensation plate is mounted on a projection type liquid crystal display device and used. Accordingly, the present invention also provides a projection type liquid crystal display device in which the optical compensation plate is disposed on at least one surface side of the liquid crystal cell. More specifically, the projection type liquid crystal display device includes an optical system having a dichroic coating layer for spectroscopy of white light sources, white light from white light sources into three primary colors of red light, green light and blue light, a liquid crystal cell, a polarization conversion element, and the optical compensation plate. It is provided. In this case, the optical system includes, for example, a dichroic mirror, a total reflection mirror and a condenser lens for spectroscopy of white light from a white light source into three primary colors of red light, green light and blue light.

Embodiments of the Invention

Next, the present invention will be described in detail. In the present invention, a transparent film having an antireflection layer on the surface and a small photoelastic coefficient is used. This transparent film consists of a resin film whose photoelastic coefficient is 7x10 <^{13> -cm <} 2> / dyne or less. The photoelastic coefficient of this transparent resin film becomes like this. Preferably it is 6 * 10 <^13> -cm <2> / dyne or less. By using the transparent film which consists of such a resin film with a small photoelastic coefficient, generation of the phase difference by heat deformation and distortion of a film can be prevented. When the photoelastic coefficient of this film becomes larger than 7x10 <^{13> -cm <} 2> / dyne, since a new phase difference arises by the distortion generate | occur | produced by heat, and polarization will be disturbed, color deviation will occur easily in an image. The lower limit of the photoelastic coefficient may be, for example, a resin having a photoelastic coefficient of about 0.1 × 10 ⁻¹³ cm 2 / dyne without particular limitation.

Photoelasticity refers to a phenomenon in which anisotropy, ie, birefringence of 0, causes an internal stress by applying external force to exhibit anisotropy and exhibit birefringence. When the stress acting on the material (force acting per unit area) is σ and the birefringence is Δn, the stress σ and the birefringence Δn are theoretically proportional to each other.

Δn = Cσ (1)

Where C is the photoelastic coefficient. In other words, if the stress sigma acting on the material is taken as the horizontal axis and the birefringence Δn when the stress is applied is taken as the vertical axis, in theory, the relationship between them becomes a straight line and the gradient of the straight line is the photoelastic coefficient.

It is preferable that the glass transition temperature of resin which comprises a transparent film is 130 degreeC or more, More preferably, it is 140 degreeC or more. When the glass transition temperature of a transparent resin film is less than 130 degreeC, heat deformation becomes remarkable. As the upper limit of the glass transition temperature of the transparent resin film, for example, a resin having a glass transition temperature of about 300 ° C. may be used without particular limitation.

As such a resin having a small photoelastic coefficient, specifically, a cyclic polyolefin-based resin film containing a cyclic olefin such as norbornene or a resin film composed of a copolymer of cyclic olefin and styrene such as norbornene Can be mentioned. Examples of the cyclic polyolefin resin film include "Aton" sold by JSR, Inc. (glass transition temperature about 170 ° C, photoelastic coefficient about 4 x 10 ^-13 cm 2 / dyne), sold by Sekisui Chemical Co., Ltd. Essina "(glass transition temperature of about 140 ℃, photoelastic coefficient of about 6 × 10 ^-13 cm 2 / dyne)," Zeo Noah "(Optical glass transition temperature of about 136 ℃, photoelastic coefficient of about 6 × 10- ^{) 13} cm 2 / dyne). The thickness of a transparent film is about 20 micrometers-1 mm normally, Preferably it is about 40-150 micrometers.

The smaller the in-plane retardation value is, the more preferable the transparent film is, for example, 20 nm or less, more preferably 10 nm or less, particularly 5 nm or less. When the in-plane retardation value exceeds 20 nm, the display quality of an image may fall. Moreover, the smaller the thickness retardation value is, the more preferable. For example, it is more preferable that it is 50 nm or less, Furthermore, it is 30 nm or less, especially 10 nm or less. When the thickness direction retardation value exceeds 50 nm, the display quality of an image may fall. Here, the in-plane retardation value R and the thickness direction retardation Rt are n _x for the refractive index in the direction of maximum refractive index in plane, n _y for the refractive index in the direction orthogonal to that in plane, n _z for the thickness direction, When thickness is d, it is a value defined by following Formula (2) and (3), respectively.

R = (n _x -n _y ) × d (2)

Rt = [(n _x + n _y ) / 2-n _z ] × d (3)

In the present invention, an antireflection layer is formed on the outer surface of the transparent film having a small photoelastic coefficient, that is, when it is in contact with air. The antireflection layer is a layer that reduces reflected light at the interface with a known layer, and prevents generation of stray light caused by the reflected light. Therefore, it is preferable to form an antireflection layer such that the reflectance at a wavelength of 550 nm on this surface is 2% or less, particularly 1% or less. As the antireflection layer, those conventionally used, such as monolayers or multilayers composed of compounds selected from metals, metal oxides and metal fluorides, may be mentioned. Examples of the metal include silver and the like, and examples of the metal oxides include silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, yttrium oxide and zirconium oxide, and metal fluorides such as magnesium fluoride. Can be mentioned. This antireflection layer may be a single layer or a multilayer, such as two, three, or four or more layers. The thickness of the antireflection layer or the thickness of each layer when it is a multilayer is appropriately selected depending on the number of layers, the refractive index of the material used for each layer, and the like. Moreover, in order to improve the adhesiveness of an antireflection film and a transparent film, you may form an acryl coating layer or a hard coating layer between them.

The contact angle at the surface having the antireflection layer is preferably 80 ° or more, more preferably 100 ° or more. The contact angle here is a value when water is used as a liquid. When the contact angle at the surface in contact with air is less than 80 °, fine particles are easily attached, so that the projection type liquid crystal display device using the optical compensation plate having such a surface tends to decrease the contrast when used for a long time. There is this. The upper limit of the contact angle is 180 degrees.

When the antireflection layer surface satisfies the contact angle defined herein, the transparent film having the antireflection layer can be used in the present invention as it is. However, since the usual antireflection layer does not have the contact angle prescribed | regulated here in most cases, in this case, the said contact angle can be achieved by forming the layer which consists of a fluorine compound on the upper surface of an antireflection layer. The layer made of a fluorine compound can be formed by coating a surface with a coating liquid containing the compound. Therefore, the fluorine compound to be used is not particularly limited as long as the contact angle of the surface can be 80 ° or more, and those commonly used in order to prevent surface contamination can be used, for example, a fluorine-containing silane compound. Such a fluorine compound is conventionally used in the field of coating etc. conventionally, in order to prevent adhesion of a fingerprint etc. to a surface.

In the present invention, the transparent film having the antireflection layer is used in combination with a specific optical compensation film. The optical compensation film is a liquid crystal compound coated and oriented on the surface of the base film to compensate for the optical phase difference generated by the liquid crystal molecules in the liquid crystal cell when mounted on the projection type liquid crystal display device.

Examples of the base film of the optical compensation film include polycarbonate resins such as modified polycarbonates having a fluorene skeleton and general polycarbonates obtained from bisphenol A, cellulose resins such as diacetyl cellulose and triacetyl cellulose, and norbornene-based resins. Cyclic polyolefin resin, polysulfone resin, polyether sulfone resin, polyester resin, polyimide resin, polyamide resin, polyacrylate resin etc. which are polymers of a monomer are mentioned. The thickness of this base film is about 10-1,000 micrometers normally. The liquid crystal compound applied thereon may be, for example, a discotic liquid crystal compound or a polymer liquid crystal compound having a triphenylene skeleton. The method of orienting a liquid crystalline compound may be a conventional method. For example, the surface of the base film may be oriented in advance, the liquid crystalline compound may be applied and dried therein, and then the method of fixing the alignment of the liquid crystalline compound by heat treatment may be employed. Can be adopted. Such an optical compensation film coated with the liquid crystal compound is described, for example, in Patent Document 3. Commercially available optical compensation films having a liquid crystal compound coated and oriented include, for example, "wide view films" (also referred to as "WV films") sold by Fuji Photo Film Co., Ltd. (kinds: WV A 03B, WV A 12B, WV A 038, WV A 128) and "Niseki LC film", "Niseki NH film", and "Niseki NR film" sold by Niseki Mitsubishi Corporation.

In the present invention, the transparent film and the optical compensation film having the antireflection layer described above are adhered to a transparent glass plate to form an optical compensation plate. As a transparent glass plate, the normal silica glass plate, quartz glass plate, etc. which are called blue plate glass and white plate glass can be used. Moreover, use of sapphire glass and quartz glass with high thermal conductivity is also suitable. Sapphire glass is a single crystal of alumina (Al ₂ O ₃ ), for example, formed into a plate shape by the edge-defined film-fed growth method (EFG). The crystal glass is a single crystal of SiO ₂ , and may be a synthetic crystal or a natural crystal. It is preferable to have an antireflection layer on one side of the transparent glass plate, that is, the exposed surface. The thickness of a transparent glass plate is about 0.1-2 mm normally, Preferably it is 0.3 mm or more, More preferably, it is 0.8 mm or less. The area of the transparent glass plate is appropriately selected according to the size of the projection type liquid crystal display device. Representative examples of dimensions include rectangles or squares with one side of 10 to 100 mm, and circles and ellipses having a diameter of 5 to 100 mm.

The transparent film and the optical compensation film is laminated on the transparent glass plate. At this time, the transparent film is one outer surface, and is usually laminated in the order of the transparent glass plate / optical compensation film / transparent film. The area of the transparent film and the optical compensation film is usually about the same as or slightly smaller than the area of the transparent glass plate. It is preferable to make the area of a transparent film and an optical compensation film small so that an area with a small area may adhere to a glass surface easily, and it may stick on the inside about 0.5-5 mm from the edge of a transparent glass plate.

The transparent film, the optical compensation film, the glass plate, and the optical compensation film are usually laminated with an adhesive layer interposed therebetween. As the adhesive constituting the adhesive layer, for example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, or the like is used. Pressure sensitive adhesives generally impart a transparent and optically isotropic adhesive layer. Moreover, a pressure sensitive adhesive is also called adhesive. The thickness of an adhesive bond layer is about 10-60 micrometers normally.

In the optical compensation plate of the present invention, it is more preferable to laminate two optical compensation films coated with a liquid crystalline compound on the base film so as to be adjacent to each other. That is, when two optical compensation films are positioned on one surface side of the glass plate and arranged in the order of the transparent film / first optical compensation film / second optical compensation film having an antireflection layer so that the antireflection layer of the transparent film is the outermost, the contrast is achieved. The improvement effect is higher. In this case, the two optical compensation films are preferably arranged such that each alignment axis is substantially orthogonal. Moreover, although orthogonal (90 degree) is preferable with "almost orthogonal thing" here, it may shift | deviate within about +/- 5 degree. "Almost" used when showing an angular arrangement in another part of this specification also has the same meaning. In addition, the first optical compensation film closer to the transparent film among the two optical compensation films is almost orthogonal to or nearly perpendicular to the absorption axis of the linear polarizer in the polarization conversion element in which the alignment axis thereof is disposed adjacent to the projection type liquid crystal display device. It is preferable to arrange so that it may become parallel. Moreover, it is preferable to arrange these two optical compensation films so that the surface on the opposite side to the surface to which the liquid crystalline compound was apply | coated, ie, the base film side, may overlap.

1 and 2 show an example of the optical compensation plate according to the present invention. In the example shown in FIG. 1, the transparent film 21 and the optical compensation film 30 are laminated and adhered to the glass plate 23 on the optical compensation film 30 side to form the optical compensation plate 20. Here, the optical compensation film 30 is a liquid crystal compound layer 32 is coated and oriented on the base film 31, the liquid crystal compound layer 32 side to the transparent film 21, and the base film 31 side Adheres to the glass plate 23. The antireflection layer 27 is formed on the surface side of the transparent film 21 in contact with the air. In addition, the antireflection layer 28 is formed on the outer surface of the glass plate 23 opposite to the adhesive surface to the optical compensation film 30. When the glass plate 23 has optical anisotropy, it is necessary to make the crystal axis and the polarization axis of the polarized light transmitted through parallel or orthogonal. For example, when the glass plate 23 is sapphire glass, the C axis of the sapphire glass and the polarized light transmitted The polarization axes of the light are arranged to be nearly parallel or almost perpendicular.

In the example shown in FIG. 2, the second optical compensation film 40 is disposed between the optical compensation film 30 and the glass plate 23 in addition to the layer configuration of FIG. 1 to form the optical compensation plate 20. Thus, the optical compensation film 30 disposed on the transparent film 21 side is used as the first optical compensation film. In the second optical compensation film 40, the liquid crystal compound layer 42 is coated and aligned on the base film 41. In the example shown in FIG. 2, the two optical compensation films 30 and 40 are arranged so that each alignment axis is substantially orthogonal. These two optical compensation films are arrange | positioned so that the surface on the opposite side to the surface to which the liquid crystalline compound layers 32 and 42 were apply | coated, ie, the base film 31 and 41 side, may overlap.

3 to 5 show the relationship between the axial angles of the two optical compensation films 30 and 40 in the case where two optical compensation films 30 and 40 are laminated as shown in FIG. Both show the relationship of the axial angle in the case where two optical compensation films, ie, the 1st optical compensation film 30 and the 2nd optical compensation film 40 are laminated | stacked in this order on one side of the transparent film 21. FIG. In either case, the alignment axis of the first optical compensation film 30 and the alignment axis of the second optical compensation film 40 are arranged to be substantially perpendicular to each other. That is, the long side right direction of each of the optical compensation films 30 and 40 is 0 °, and in FIG. 3, the alignment axis of the first optical compensation film 30 is 135 ° and the second optical compensation film 40 is aligned. 4 and 5, the alignment axis of the first optical compensation film 30 is 270 °, and the alignment axis of the second optical compensation film 40 is 180 ° or 0 °. Doing. In addition, in FIG. 4 and FIG. 5, the arrow view direction indicating the alignment axis of the second optical compensation film 40 is reversed. The arrow view direction means a rubbing direction for orientation.

The optical compensating plate of the present invention can be suitably used for a projection type liquid crystal display device. For example, in the projection type liquid crystal display device, it can be used by being inserted in the optical path of each primary color light which is red light, green light or blue light after spectroscopy or white light of white light from a white light source.

Specifically, in the projection type liquid crystal display device shown in Fig. 6, between the liquid crystal cells 7R, 7G, and 7B and the incident side polarization conversion elements 8R, 8G, and 8B for each of the three primary colors or the exit side polarization conversion elements ( It can arrange | position and use between 9R, 9G, and 9B and liquid crystal cells 7R, 7G, and 7B. All between the incident side polarization conversion elements 8R, 8G, 8B and the liquid crystal cells 7R, 7G, 7B or all between the exit side polarization conversion elements 9R, 9G, 9B and the liquid crystal cells 7R, 7G, 7B. It is more effective to arrange | position the optical compensation plate of this invention to the. This optical compensating plate is generally used such that the transparent film 21 is in the glass plate 23 such that the glass plate 23 shown in FIGS. 1 and 2 is on the polarization conversion element 8R, 8G, 8B or 9R, 9G, 9B side. It is arrange | positioned so that it may become the side closer to liquid crystal cells 7R, 7G, and 7B.

An example of arrangement in such a projection type liquid crystal display device is shown in cross-sectional schematic diagram in FIG. 7. FIG. 7A is an example in which the optical compensating plate 20 shown in FIG. 1 is disposed between the liquid crystal cell 7 and the incident or exit-side polarization conversion elements 8 or 9, and FIG. The optical compensation plate 20 shown in 2 is an example arrange | positioned between the liquid crystal cell 7 and the incident side or the emission side polarization conversion element 8 or 9. In any case, the transparent film 21 constituting the optical compensation plate 20 is disposed on the liquid crystal cell 7 side and the glass plate 23 on the polarization conversion element 8 or 9 side. In addition, although not shown, the polarization conversion elements 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 adhered. In addition, the polarizing plate may be directly adhered to the glass surface opposite to the surface on which the optical compensation film 30 or 40 of the optical compensation plate is adhered to form a polarization converting element. In addition to being easily blown, the cooling efficiency is also improved. In particular, for the emission-side polarization conversion element, a polarizing plate (pre-polarizing plate) having a high transmittance is used for the purpose of protecting the polarizing plate disposed thereon, on the side opposite to the surface on which the optical compensation film 30 or 40 of the optical compensation plate is adhered. It can also be made to adhere to a phosphorus glass surface, and a normal polarizing plate (cast polarizing plate) can be attached to the outside thereof so that its transmission axis is parallel to the transmission axis of the pre-polarizing plate, thereby making it a polarization conversion element. In this case, since light is absorbed to some extent by the polarizing plate (pre-polarizing plate) with high transmittance, light absorption in the main polarizing plate arranged next can be reduced. Examples of the polarizing plate having a high transmittance for this purpose include "STX8C2A-HC-AR", "STX8B2A-HC-AR", "STX8A2A-HC-OB" sold by Sumitomo Chemical Industries, Ltd., and the like.

On the other hand, there is also a projection type liquid crystal display device that directly expands the spectral light from the color filter in the form of a single plate, in which case the optical compensation plate of the present invention is disposed in front or behind the liquid crystal cell including the color filter in the optical path of the white light. .

Example

Next, although a specific example is shown and this invention is demonstrated in detail, this invention is not limited by these examples.

Example 1

As the cyclic polyolefin-based transparent resin film, antireflective treatment and fluorine-containing silane compound were carried out in this order on one surface of "Aton" (photoelastic coefficient about 4x10 ^-13 cm 2 / dyne) sold by JSR. This was made into a transparent film (in-plane retardation value 4 nm, thickness direction retardation value 46 nm). As an optical compensation film in which a liquid crystalline compound is coated and oriented on a base film on the side opposite to the anti-reflective surface of this transparent film, two sheets of "Wide View Film WV A03B" sold by Fuji Photo Film Co., Ltd. are each adhesive. Laminated through. At this time, the two optical compensation films were arranged at the same axial angle as shown in Fig. 5, and the base film surfaces on the opposite side to the surface on which the liquid crystal compound layers were formed were faced with each other. In addition, anti-reflective treatment is performed on one surface of a sapphire glass plate having a diagonal dimension of 0.9 inch (about 23 mm) sold by Kyocera Co., Ltd., and the transparent film / first optical compensation film / second optical The laminated body of the compensation film was stuck on the liquid crystalline compound layer side of the second optical compensation film to prepare an optical compensation plate having the configuration shown in FIG. 2. At this time, the adhesion axis of the second optical compensation film and the C axis of the sapphire glass coincide with each other.

Between the liquid crystal panel of red (R), green (G) and blue (B) and each emission side polarization conversion element of the projection type liquid crystal display device, the optical compensation plate obtained above is used as the glass plate. When it was observed to be on the side, the contrast on the screen was improved and the screen deviation of the black display was also small, resulting in improved display quality.

Comparative Example 1

Anti-reflection on one surface of the triacetyl cellulose film (photoelastic coefficient about 10 × 10 ^-13 cm 2 / dyne) (in-plane retardation value 7 nm, thickness direction retardation value 56 nm) sold by Fuji Photo Film Co., Ltd. as a transparent film. An optical compensation plate was manufactured in the same manner as in Example 1, except that the treated material was used. When the optical compensation plate was set in the projection type liquid crystal display device in the same manner as in Example 1, the contrast was always on the screen, but the display quality of the black display was low.

The optical compensating plate of the present invention arranges a specific transparent film and an optical compensating film having an antireflection layer in a specific order, and is effectively used in a projection type liquid crystal display device, and the projection type liquid crystal display device in which the optical compensation plate is disposed is an image to be projected. The contrast is increased and the screen deviation of the black display is eliminated, resulting in an excellent display quality.

Claims (7)

A transparent film having a photoelastic coefficient of 7 × 10 ⁻¹³ cm 2 / dyne or less and having an antireflection layer formed thereon, an optical compensation film and a transparent glass plate formed by applying a liquid crystal compound to a base film, The optical compensation plate, characterized in that the antireflection layer of the transparent film is laminated so as to be the outermost. The method of claim 1, An optical compensation plate, wherein two optical compensation films formed by applying a liquid crystalline compound to the base film are laminated. The method of claim 2, And the two optical compensation films are arranged such that each of the alignment axes forms an angle of 90 ° ± 5 °. The method of claim 2, And the two optical compensation films are laminated so that the surface of the base film on the side opposite to the surface on which the liquid crystal compound is applied is overlapped. The method of claim 1, An in-plane retardation value of 20 nm or less and a thickness direction retardation value of 50 nm or less of said transparent film were used, The optical compensation plate characterized by the above-mentioned. The method of claim 1, The optical compensation plate, wherein the transparent glass plate is sapphire glass. A projection type liquid crystal display device comprising the optical compensation plate according to any one of claims 1 to 6 arranged on one surface side of a liquid crystal cell.

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