JP2003004947A - Polarization converting element and projection liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarization converting element exhibiting high contrast and realizing a bright projection liquid crystal display device with high uniformity and apply it to the projection liquid crystal display device. SOLUTION: The polarization converting element 20 which comprises a transparent glass plate 21 having at least two sheets of optical retardation plates 22, 23 composed of a resin with >=120 deg.C glass transition temperature laminated thereon and further a linearly polarizing plate 24 laminated on the surface of the optical retardation plates on the side opposite to the glass plate is provided. The polarization converting element 20 is disposed on at least one surface side of the liquid crystal cell with the linearly polarizing plate 24 side facing to the liquid crystal cell so as to obtain the projection liquid crystal display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization conversion element used in a projection type liquid crystal display device, and further relates to a projection type liquid crystal display device using the same.

[0002]

2. Description of the Related Art A projection type liquid crystal display device is widely used as a device capable of enlarging and projecting a screen of a personal computer, a television or the like.

An example of the configuration of the projection type liquid crystal display device will be briefly described with reference to FIG. 3. Such a projection type liquid crystal display device usually has a light source system, a reflection / spectroscopic system, and a magnifying projection system. The light source system includes a white light source 11, a condenser lens 13 and UV.
・ White light source 1 with IR cut filter 14
The white light L from 1 is condensed by the condenser lens 13, and further U
The V / IR cut filter 14 cuts ultraviolet rays and infrared rays and sends them 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 reflection / spectroscopic system comprises four types of dichroic mirrors 1, 2, 3, 4 and two total reflection mirrors 5, 6, a liquid crystal cell 7R corresponding to red light R, green light G and blue light B, respectively. 7G and 7B, incident side polarization conversion elements 8R and 8
G and 8B, output side polarization conversion elements 9R, 9G and 9B,
It also has condenser lenses 10R, 10G and 10B.

The first dichroic mirror 1
Is for transmitting only the green light G and the blue light B,
The green light G and the blue light B transmitted therethrough are sent to the second dichroic mirror 2. The red light R reflected by the first dichroic mirror 1 is sent to the first total reflection mirror 5, and after being reflected there, the condenser lens 10R for red, the incident side polarization conversion element 8R, the liquid crystal. It is sent to the third dichroic mirror 3 through the cell 7R and the exit side polarization conversion element 9R. On the other hand, the second dichroic mirror 2 transmits only the green light G, and the green light G and the blue light B transmitted through the first dichroic mirror 1 are transmitted.
Among them, the green light G transmitted through the second dichroic mirror is the green condenser lens 10G and the incident side polarization conversion element 8
It is sent to the second total reflection mirror 6 through G, the liquid crystal cell 7G and the exit side polarization conversion element 9G. Further, the blue light B reflected by the second dichroic mirror 2 passes through a blue condensing lens 10B, an incident side polarization conversion element 8B, a liquid crystal cell 7B and an emission side polarization conversion element 9B, and a third dichroic It is sent to the mirror 3. The third dichroic mirror 3 transmits only the red light R,
The red light R that has passed from the first total reflection mirror 5 through the red condenser lens 10R, the incident side polarization conversion element 8R, the liquid crystal cell 7R, and the emission side polarization conversion element 9R is transmitted through the third dichroic mirror 3 as it is. Further, the blue light B that has passed from the second dichroic mirror 2 through the condenser lens 10B for blue, the incident side polarization conversion element 8B, the liquid crystal cell 7B, and the emission side polarization conversion element 9B is reflected by the third dichroic mirror 3. The reflected light is sent to the fourth dichroic mirror 4. The fourth dichroic mirror 4 transmits only the red light R and the blue light B, the red light R and the blue light B from the third dichroic mirror 3 are transmitted therethrough as they are, and the second total reflection. The green light G from the mirror 6 is reflected here and sent to the projection lens 16, respectively.

The magnifying projection system has a projection lens 16 in which an image corresponding to each light is magnified,
An enlarged image will be projected on the screen 17. In addition,
Incident side polarization conversion elements 8R, 8G, 8B of liquid crystal cells 7R, 7G, 7B corresponding to respective colors and emission side polarization conversion element 9
R, 9G, 9B may be used by being bonded to the liquid crystal cells 7R, 7G, 7B, but normally, the liquid crystal cells 7R, 7B are used.
G and 7B are arranged with a space, and this space is
It serves as a ventilation passage for cooling. In addition, the incident side polarization conversion element 8
R, 8G and 8B are condenser lenses 10R, 10G and 10B
The distance is kept. In this way, the polarization conversion element 8
R, 8G, 8B, 9R, 9G and 9B are replaced by liquid crystal cells 7R and 7
When it is arranged apart from the G, 7B and the condenser lenses 10R, 10G, 10B, the linear polarizing plate is used by being attached to a reinforcing material such as glass.

In such a projection type liquid crystal display device, each of the liquid crystal cells 7R, 7G and 7B has two polarization conversion elements, that is, incident side polarization conversion elements 8R and 8G, respectively.
8B and the exit side polarization conversion elements 9R, 9G and 9B. These polarization conversion elements 8 and 9 generate a large amount of heat because the amount of light necessary for enlarging and projecting an image on the screen is transmitted. In addition, red light R, green light G
And / or the blue light B is polarized light, the liquid crystal cell 7
It is often necessary to rotate the plane of polarization when entering the R, 7G, and 7B. Further, liquid crystal cells 7R, 7G,
The polarized light emitted from 7B may rotate the plane of polarization again.

In order to rotate the plane of polarization, a λ / 2 phase difference plate may be used, and the phase difference plate is usually the light source 11 side of the incident side polarization conversion elements 8R, 8G, 8B or the emission side polarization conversion element. It is arranged on the side of the projection lens 16 of 9R, 9G, 9B. As the retardation plate, a resin retardation plate is usually used from the viewpoint of easy availability and price. This retarder is
In the incident side polarization conversion elements 8R, 8G, 8B or the emission side polarization conversion elements 9R, 9G, 9B, they are used by being attached to a linear polarizing plate.

[0009]

An ordinary polarization conversion element in which one such retardation plate is bonded is one which efficiently rotates the plane of linear polarization only in a specific narrow wavelength range. In the wide wavelength range of each of green and blue, the plane of polarization cannot be efficiently rotated, and there is a problem that display quality such as contrast and brightness is not sufficient.

Therefore, the present inventor has conducted research to develop a polarization conversion element which can realize a projection type liquid crystal display device which exhibits high contrast, is bright, and has high uniformity.
In a polarization conversion element in which a glass substrate, a retardation plate, and a polarizing plate are laminated in this order, a polarization conversion element in which two or more specific retardation films are laminated at a specific angle is used for contrast and brightness of an image projected. It was found that a projection type liquid crystal display device having improved display quality such as uniformity can be provided, and the present invention has been completed.

[0011]

That is, according to the present invention, at least two retardation plates made of a resin having a glass transition temperature of 120 ° C. or more are laminated on a transparent glass plate, and the glass plate of the retardation plate is further laminated. The present invention provides a polarization conversion element in which a linear polarizing plate is laminated on the surface opposite to the surface.

This polarization conversion element is used by being incorporated in a projection type liquid crystal display device. Therefore, the present invention also
There is also provided a projection type liquid crystal display device in which the polarization conversion element is arranged on at least one surface side of a liquid crystal cell. More specifically, this projection type liquid crystal display device includes a white light source and an optical component having a dichroic coat layer for splitting white light from the white light source into light of three primary colors of red light, green light and blue light. , The liquid crystal cell and the polarization conversion element described above, and the polarization conversion element is arranged with the linear polarizing plate side facing the liquid crystal cell.

[0013]

FIG. 1 shows an example of a polarization conversion element according to the present invention. As shown in this figure, in the present invention,
A first retardation plate 22 and a second retardation plate 23 are laminated on a transparent glass plate 21, and a linear polarizing plate 24 is provided on the surface of the second retardation plate 23 opposite to the glass plate 21. The polarization conversion element 20 is formed by stacking the layers. In this example,
Although the structure using two retardation plates is shown, it is also possible to use three or more retardation plates.

The transparent glass plate 21 applied to the polarization conversion element of the present invention may be any glass suitable for a projection type liquid crystal display device, such as blue plate glass, white plate glass, sapphire glass. The sapphire glass is a single crystal body of alumina (Al ₂ O ₃ ), for example, EFG method (Edge-defined F
The plate-shaped one formed by the ilm-fed growth method) is used. The thickness of the glass plate 21 is usually 0.1 to 2 m.
It is about m, preferably about 0.3 to 0.8 mm.
The shape and external dimensions of the glass plate 21 are appropriately selected depending on the shape and external dimensions of the target projection type liquid crystal display device, particularly the liquid crystal cell used therein. There are rectangles or squares of -100 mm, circles or ellipses of 5-100 mm in diameter, and the like.

The glass plate 21 preferably has an antireflection layer 26 on the surface opposite to the side where the retardation plates 22 and 23 and the linear polarizing plate 24 are laminated, that is, on the exposed surface. Further, the glass plate 21 may have a characteristic that a dichroic coat layer is formed on one surface or both surfaces of the glass plate 21 so that only light in a specific wavelength range is transmitted and light in other wavelength ranges is not transmitted. If you have a dichroic coat layer on one side,
The retardation plates 22, 23 and the linear polarizing plate 24 may be laminated on the dichroic coat layer, or the retardation plates 22, 23 and the linear polarizing plate 24 may be laminated on the surface opposite to the dichroic coat layer. Good.

At least two retardation plates 22 and 23 are laminated on the glass plate 21.
It is made of a resin having a glass transition temperature of 0 ° C. or higher. When a retardation plate made of a resin having a glass transition temperature of less than 120 ° C. is used, the display quality is likely to deteriorate when a projection type liquid crystal display device incorporating the retardation plate is used for a long time. Therefore, the glass transition temperature is preferably 130 ° C.
A retardation plate made of the above resin is used. There is no particular limitation on the upper limit of the glass transition temperature of the resin forming the retardation plate, and for example, a resin having a glass transition temperature of about 300 ° C. may be used.

As the resin having such a high glass transition temperature, for example, a polycarbonate resin (for example,
Teijin Kasei's "Panlite" etc., cellulosic resins such as diacetyl cellulose and triacetyl cellulose, cyclic polyolefin resins using norbornene monomers (for example, "Arton" manufactured by JSR Co., Ltd.) , "Zeonex" manufactured by Nippon Zeon Co., Ltd.), polysulfone-based resins, polyether sulfone-based resins, polyester-based resins, polyimide-based resins, polyamide-based resins, polyarylate-based resins and the like.

To make a retardation plate from these resins, for example, a film made of these resins may be stretched, and a retardation plate having a desired retardation can be obtained depending on the degree of stretching. . Alternatively, a commercially available retardation plate can be used.

The phase difference plates 22 and 23 are usually 1/2
A wave plate is used, and its retardation is about 280 to 350 nm when the light transmitted through the wave plate is red light, and about 250 to 300 nm when the light is green light, and blue light is also used. 210 to 250
It is about nm. Examples of commercially available retarders suitable for use in the present invention include “Sumikalite SEF460225” and “Sumikalite SE” sold by Sumitomo Chemical Co., Ltd.
F460275 "," Sumikalite SEF460305 ", etc. (both are made of polycarbonate resin, glass transition temperature is about 150 ° C, retardation" SEF460225 "is about 225nm," SEF460275 "is about 275nm," SEF460305 "
Is about 305 nm). The thickness of the retardation plate is usually about 10 to 500 μm.

The retardation plates 22 and 23 are laminated on one surface of the glass plate 21 with an adhesive layer (not shown) interposed therebetween, for example. As the adhesive constituting the adhesive layer, for example,
Pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives and urethane pressure-sensitive adhesives are preferably used. Pressure sensitive adhesives typically provide a transparent, optically isotropic adhesive layer. The thickness of the adhesive layer is usually about 10 to 60 μm. In addition,
The pressure sensitive adhesive is also called an adhesive.

The polarization conversion element 20 of the present invention includes a phase difference plate (two phase difference plates) arranged on the surface of the phase difference plate opposite to the glass plate 21, specifically, on the side far from the glass plate 21. When using a plate, the glass plate 21 of the second retardation plate 23)
The linear polarizing plate 24 is further laminated on the surface opposite to the surface. As the linearly polarizing plate 24, one having a protective film laminated on one side or both sides of a polarizer film is usually used. As the polarizer film, for example, a polyvinyl alcohol-based resin film in which a dichroic dye or iodine is adsorbed and oriented is used. It is preferably used in. As the protective film, for example, a film made of a cellulosic resin such as diacetyl cellulose or triacetyl cellulose is used.

The linear polarizing plate 24 is provided on the phase plate 23.
For example, they are laminated via an adhesive layer (not shown). The thickness of the adhesive layer is usually about 10 to 60 μm. As the adhesive constituting the adhesive layer, the same pressure-sensitive adhesive as described above for the lamination of the glass plate 21 and the retardation plate 22 is used. This pressure-sensitive adhesive preferably has a relaxation elastic modulus reduction rate at 25 ° C. in the range of −0.14 to −0.09.

Adhesives generally exhibit viscoelasticity, and if strain γ ₀ is momentarily applied to the viscoelastic body and then it is kept constant, the stress σ (t) decreases with the passage of time to a constant value. This is called stress relaxation, and the stress σ (t) to be relaxed at this time can be expressed as σ (t) = G (t) · γ _0, and G (t)
Is a time-dependent elastic modulus, which is called relaxation elastic modulus.
In other words, the relaxation elastic modulus is the ratio of the stress σ (t) that decreases with time and the constant strain γ ₀ applied from the outside. And, the decrease rate of the relaxation elastic modulus at 25 ° C. is the temperature 25
It means the linear gradient when the relaxation elastic modulus G (t) measured at ° C is plotted on the vertical axis and the time t (unit: second) on the horizontal axis, and is expressed by the following equation log ₁₀ [G (t) ] = A · log ₁₀ [t] + b, where a and b are constants. The relaxation rate a of relaxation elastic modulus is relative to log ₁₀ [t]
It can be obtained from the value of log ₁₀ [G (t)] by the method of least squares.

When laminating at least two retardation plates and a linear polarizing plate to form a polarization conversion element, respective laminating axis angles are important. For example, as shown in FIG. 1, when two retardation plates are used and the first retardation plate 22, the second retardation plate 23, and the linear polarizing plate 24 are laminated in this order, The angle between the slow axis of the retardation plate 22 and the slow axis of the second retardation plate 23 is 45 degrees, and the angle between the slow axis of the second retardation plate 23 and the transmission axis of the polarizing plate 24. Is 22.5 degrees, or the angle between the slow axis of the first retardation plate 22 and the slow axis of the second retardation plate 23 is 22.5 degrees, and the second retardation plate It is suitable that the angle formed by the slow axis of 23 and the transmission axis of the polarizing plate 24 is 11.25 degrees. These angles are required to have an accuracy within ± 2 degrees, preferably within ± 1 degrees.

The relationship between these axis angles is shown in FIG. Figure 2
In (A) of, with respect to the slow axis 22a of the first retardation plate,
The angle θ _{1 at} which the slow axis 23a of the second retardation plate intersects is about 4
The angle θ _{2 at} which the transmission axis 24a of the polarizing plate intersects the slow axis 23a of the second retardation plate is about 22.
It is 5 degrees. In FIG. 2B, the slow axis 23a of the second retardation plate is opposed to the slow axis 22a of the first retardation plate.
Has become the angle theta ₁ is about 22.5 degrees intersect to a second slow axis 23a of the retardation plate, the transmission axis 24a of the polarizer
The angle θ _{2 at} which the points intersect is about 11.25 degrees.

When three retardation plates are used and a first retardation plate, a second retardation plate, a third retardation plate and a linear polarizing plate are laminated in this order to form a polarization conversion element. Is, the angle formed by the slow axis of the first retardation plate, the slow axis of the second retardation plate and the slow axis of the third retardation plate is 30 degrees adjacent to each other. The angle formed by the slow axis of the third retardation plate and the transmission axis of the polarizing plate is 15 degrees, or the slow axis of the first retardation plate and the slow axis of the second retardation plate The angle between the slow axis of the third retardation plate and the slow axis of the third retardation plate is 15 degrees, and the angle between the slow axis of the third retardation plate and the transmission axis of the polarizing plate is 7.5 degrees. Is appropriate. Also in this case, each angle is ± 2
Accuracy within ± 1, preferably within ± 1 ° is required. Although the illustration of the shaft angle in this case is omitted, it can be easily understood from the example of FIG.

In the polarization conversion element 20 of the present invention, one surface 27 of the linear polarizing plate 24 is exposed to the air layer, and the reflectance on this exposed surface 27 is 2% or less, and further 1 % Or less is preferable because generation of stray light due to reflected light can be suppressed. To reduce the reflectance in this way, for example, the exposed surface 2 of the linearly polarizing plate 24 is
7, the antireflection layer 28 may be formed. Antireflection layer 2
8 can be provided on the surface of the linear polarizing plate 24 by a usual method. The reflectance on the exposed surface 27 of the linear polarizing plate 24 may be 2% or less over the entire visible light range, but it is effective if it is 2% or less with respect to the wavelength range of the light transmitted through the linear polarizing plate. Is.

Examples of the antireflection layer 28 include a commonly used antireflection layer, for example, a single layer or a multi-layered layer made of a compound selected from metals, metal oxides and metal fluorides. Examples of the metal include silver and the like, and examples of the metal oxide include silicon oxide,
Examples thereof include aluminum oxide, titanium oxide, tantalum oxide, yttrium oxide, zirconium oxide, and the like, and examples of the metal fluoride include magnesium fluoride and the like. The antireflection layer 28 may be a single layer or a multilayer including two layers, three layers, four layers or more layers. The thickness of the antireflection layer 28 and the thickness of each layer when it is a multilayer are appropriately selected depending on the number of layers, the refractive index of the substance used for each layer, and the like. Since a linear polarizing plate having an antireflection layer is also commercially available, it can be used as it is.

In the polarization conversion element 20 of the present invention, the contact angle on the outer surface 27 of the linear polarizing plate 24, for example, the surface having the antireflection layer 28, is preferably 80 degrees or more, and more preferably 100 degrees or more. Those having an angle are more preferable. The contact angle here is a value when water is used as the liquid. If the contact angle on the outer surface of the linear polarizing plate 24 is less than 80 degrees, fine particles such as dust are likely to adhere to the linear polarizing plate 24. Therefore, the projection type liquid crystal display device using the polarization conversion element having such a surface is used for a long period of time. In that case, the contrast tends to decrease. The upper limit of the contact angle is 180 degrees.

The linear polarizing plate itself, which is obtained by laminating a protective film on one side or both sides of a polarizer film in which a dichroic dye or iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film, is also used in a conventional projection type liquid crystal display device. In addition, a linear polarizing plate having an antireflection layer is also commercially available. When the surface having the antireflection layer 28 satisfies the contact angle defined here, the linear polarizing plate 24 having the antireflection layer 28 can be directly used for the polarization conversion element of the present invention. However, since many ordinary antireflection layers do not have the contact angle defined here, in this case, a layer made of a fluorine compound may be provided on the upper surface of the antireflection layer 28.

The fluorine compound used for this purpose is not particularly limited as long as the contact angle can be 80 degrees or more.
Examples thereof include those usually used for preventing surface contamination, such as fluorine-containing silane compounds.
Such a fluorine compound is usually used to prevent dirt such as fingerprints from adhering to the surface. As such a fluorine-containing silane compound, specifically, for example,
Examples thereof include those represented by the following general formula (I).

[0032]

In the formula, R ⁰ 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, and Z is a fluorine atom. Or a trifluoromethyl group, R ¹ is a hydrolyzable group, R ² is a hydrogen atom or an inert monovalent organic group, and a, b, c and d each independently represent an integer of 0 to 200. , E is 0 or 1, m is an integer of 0 to 2, and n is 0.
˜2, and p represents an integer of 1 or more.

More specifically, for example, a fluorine-containing silane compound represented by the following formula (II) and having a molecular weight of about 4,500 can be mentioned (for these fluorine-containing silane compounds, see, for example, JP-A-1- (See Japanese Patent No. 294709).

[0035]

In the polarization conversion element 20 of the present invention, since one surface of the linear polarizing plate 24 is exposed to the air layer, the linear polarizing plate 2
The heat generated from the phase difference plate 2 is easily released.
As 2, a resin made of a resin that does not show a glass transition point at a specific temperature or lower is used, and therefore, the projection type liquid crystal display device using this polarization conversion element has less deterioration in display quality of a projected image.

Specifically, this polarization conversion element is used by being arranged on at least one surface side of a liquid crystal cell which constitutes a projection type liquid crystal display device. More specifically, in the projection type liquid crystal display device as shown in FIG. 3, the incident side polarization conversion elements 8 of the liquid crystal cells 7R, 7G and 7B corresponding to the respective three primary colors.
R, 8G, 8B, and output side polarization conversion elements 9R, 9G,
It can be used as at least one of 9B. Therefore, in this case, an optical component having a white light source 11 and a dichroic coat layer for splitting the white light L from the white light source 11 into light of three primary colors of red light R, green light G and blue light B (usually a dichroic mirror) Called) 1,
2, 3, liquid crystal cells 7R, 7G, 7B, and at least one of the liquid crystal cells 7R, 7G, 7B on the incident side or the emitting side of the polarization conversion element of the present invention. This polarization conversion element is a linear polarization plate 2 shown in FIG.
The four sides are arranged with the liquid crystal cell facing.

Among the three primary colors of light that are dispersed in the projection type liquid crystal display device, the green light has a large amount of light, and
Since the luminous efficiency is high, the incident side polarization conversion element 8G and the emission side polarization conversion element 9 of the liquid crystal cell 7G corresponding to the green light G.
The polarization conversion element 20 of the present invention is preferably used for G, but, of course, the incident side polarization conversion element 8R and the emission side polarization conversion element 9R corresponding to the red light R, and the incidence side corresponding to the blue light B are also included. Polarization conversion element 8B and emission side polarization conversion element 9
It is also possible to apply the polarization conversion element 20 of the present invention to B. It is also effective to apply the polarization conversion element of the present invention to all of the incident side polarization conversion elements 8R, 8G, 8B and the emission side polarization conversion elements 9R, 9G, 9B.

[0039]

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

A polyvinyl alcohol / dichroic dye type polarizing plate sold by Sumitomo Chemical Co., Ltd., which has a non-reflective treatment layer on one side, "Sumikaran SWW83".
A fluorine-containing silane compound having a molecular weight of about 4,500 corresponding to the above formula (II) was coated on the surface of the 2A ″ antireflection layer. The obtained fluorine-containing silane compound-coated surface had a contact angle of 110 °. The surface of the linear polarizing plate opposite to the surface coated with the fluorine-containing silane compound is a polycarbonate retardation plate “Sumikalite SEF460275” (glass transition) sold by Sumitomo Chemical Co., Ltd. Temperature about 15
Two sheets (0 ° C.) were pasted together via an adhesive to form a layer structure composed of a first retardation plate / second retardation plate / polarizing plate as shown in FIG. When laminating, the slow axis of the second retardation plate forms an angle of 22.5 degrees with respect to the transmission axis of the polarizing plate, and the second position with respect to the slow axis of the first retardation plate. The retardation plate was arranged so that the slow axis was inclined by 45 degrees. Further, a glass plate was attached to the retardation plate side to produce a polarization conversion element. When this polarization conversion element is set on the green channel line of a projection type liquid crystal display device (liquid crystal projector) and used, the brightness and contrast of the projected image are improved.

In the above example, if the retardation plate is replaced by the polycarbonate retardation plate "Sumikalite SEF460305" (glass transition temperature about 150 ° C) also sold by Sumitomo Chemical Co., Ltd., projection type liquid crystal A polarization conversion element effective for the red channel line of the display device (liquid crystal projector) can be obtained. Also, the polarizing plate is a polyvinyl alcohol / dichroic dye type polarizing plate which is also sold by Sumitomo Chemical Co., Ltd., and has a non-reflective treatment layer on one side, "Sumikaran SCX8A2A-HC-AR-". "O2" and the retardation plate made of polycarbonate, which is also sold by Sumitomo Chemical Co., Ltd. "Sumikalite SEF4602
If it is changed to 25 ″ (glass transition temperature of about 150 ° C.), a polarization conversion element effective for the blue channel line of a projection type liquid crystal display device (liquid crystal projector) can be obtained.

[0042]

INDUSTRIAL APPLICABILITY The polarization conversion element of the present invention is effectively used in a projection type liquid crystal display device, and a projection type liquid crystal display device in which the polarization conversion element is arranged on the incident side and / or the emission side of a liquid crystal cell is a projection type liquid crystal display device. The contrast and brightness of the displayed image are improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a polarization conversion element according to the present invention.

FIG. 2 is an explanatory diagram showing the relationship between the axial angles of two retardation plates and a polarizing plate.

FIG. 3 is a diagram schematically showing a configuration example of a projection type liquid crystal display device.

[Explanation of symbols]

1, 2, 3, 4 ... Dichroic mirror, 5, 6 ... Total reflection mirror, 7R, 7G, 7B ... Liquid crystal cell, 8R, 8G, 8B ... Incident side polarization conversion element, 9R, 9G, 9B ... Emission side polarization conversion element, 10R, 10G, 10B ... Condensing lens, L: White light (light source), R ... red light, G: green light, B ... blue light 11 ... White light source, 13 ... Condensing lens, 14 …… UV / IR cut filter, 16 ... Projection lens, 17 ... screen, 20 ... Polarization conversion element, 21 ... glass plate, 22 ... the first retardation plate, 22a ... the slow axis of the first retardation plate, 23 ... the second retardation plate, 23a ... The slow axis of the second retardation plate, 24: Linear polarizing plate, 24a ... Transmission axis of linearly polarizing plate 26: Antireflection layer on glass plate, 27: the outer surface of the linear polarizing plate, 28: Antireflection layer on the linear polarizing plate.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1333 505 G02B 1/10 A 2K009 1/1335 Z F term (reference) 2H042 DA08 DB01 DB02 DE00 2H049 BA02 BA06 BA27 BA42 BB03 BB42 BB43 BB52 BB65 BB68 BC03 BC22 2H088 EA15 HA04 HA13 HA15 HA18 MA02 MA04 2H090 HB12X HB13X HD01 HD04 LA05 LA06 LA09 2H091 FA05Z FA07X FA07X FA37X FA07X FA37Z FA02Z02

Claims (9)

[Claims] 1. A transparent glass plate having a glass transition temperature of 12
At least two retardation plates made of a resin having a temperature of 0 ° C. or higher are laminated, and a linear polarizing plate is further laminated on the surface of the retardation plate opposite to the glass plate, for a projection type liquid crystal display device. Polarization conversion element. 2. The polarization conversion element according to claim 1, wherein the glass plate has an antireflection layer on its exposed surface. 3. The polarization conversion element according to claim 1, wherein the linear polarizing plate has an antireflection layer on its exposed surface. 4. The polarization conversion element according to claim 1, wherein the surface contact angle on the exposed surface of the linear polarizing plate is 80 degrees or more. 5. The polarization conversion element according to claim 4, wherein a layer of a fluorine compound is provided on the outermost surface of the exposed surface of the linear polarizing plate, and the contact angle is 80 degrees or more. 6. A first retardation plate, a second retardation plate and a polarizing plate are laminated in this order, and a slow axis of the first retardation plate and a slow phase of the second retardation plate. 6. The angle formed by the axis is 45 ± 2 degrees, and the angle formed by the slow axis of the second retardation plate and the transmission axis of the polarizing plate is 22.5 ± 2 degrees. The polarization conversion element described in 1. 7. A first retardation plate, a second retardation plate and a polarizing plate are laminated in this order, and a slow axis of the first retardation plate and a slow phase of the second retardation plate. The angle with the axis is 22.5 ±
The polarization conversion element according to any one of claims 1 to 5, wherein the polarization axis is 2 degrees, and the angle formed by the slow axis of the second retardation plate and the transmission axis of the polarizing plate is 11.25 ± 2 degrees. 8. A projection type liquid crystal display device, wherein the polarization conversion element according to claim 1 is arranged on at least one surface side of a liquid crystal cell. 9. A liquid crystal cell, an optical component having a white light source, a dichroic coat layer for separating white light from the white light source into light of three primary colors of red light, green light and blue light, and a liquid crystal cell. 9. The projection type liquid crystal display device according to claim 8, further comprising: the polarization conversion element according to any one of claims 1 to 7, wherein the polarization conversion element is arranged with the linear polarizing plate side facing the liquid crystal cell.