JPH11231132A - 1/4-wavelength plate, circular polarizing plate, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circular polarizing plate which hardly causes color difference in reflected light between front view and oblique view and has superior wide-band characteristics for reflection prevention, heat resistance, etc., by obtaining a wavelength plate which functions as a 1/4-wavelength plate over a wide wavelength range of the entire visible light range, etc., and hardly causes differences in phase difference characteristics between front view and oblique view. SOLUTION: This device has the 1/4-wavelength plate 5 which is formed by stacking drawn films 1 and 3 giving a phase difference of 1/2 or 1/4 wavelength to monochromatic light so that their optical axes cross each other while one of the drawn films has a <=50×1/10<13> cm<2> /dyn coefficient of photoelasticity to light of 633 nm in wavelength and wavelength dependency Δn1 /Δn2 <1.05 of birefringence differences Δn1 and Δn2 to lights of 500(Δn1 ) and 550 nm (Dn) in wavelength and circular polarizing plates 1 to 5 consisting of the 1/4-wavelength plate 5 and polarizing plate 4. Consequently, the circular polarizing plates 1 to 5 are obtained which have superior field angle characteristics and wide-band characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a quarter-wave plate that provides a phase difference of four wavelengths, a circularly polarizing plate that prevents reflection over a wide wavelength range and is excellent in viewing angle and durability, and a liquid crystal display device that is excellent in viewing characteristics.

[0002]

2. Description of the Related Art Conventionally, a quarter-wave plate using one stretched film has been known. However, there is a problem that the phase difference differs for each wavelength, and the wavelength that can function as a quarter-wave plate is limited to a specific wavelength. That is, for example, in the case of a device that functions as a quarter-wave plate for light having a wavelength of 550 nm, it does not function as a quarter-wave plate for light having a wavelength of 450 nm or 650 nm. Therefore, for example, when a circularly polarizing plate is adhered to a polarizing plate and used as an antireflection filter for suppressing surface reflection of a display or the like, a sufficient antireflection function is exhibited for light having a wavelength other than 550 nm. However, there is a problem that the display or the like looks blue due to a poor antireflection function particularly for blue light.

[0003] In view of the above, the group to which the present inventors belong firstly forms a 1/4 wavelength by laminating a plurality of stretched films giving a phase difference of 1/4 wavelength and 1/2 wavelength with their optical axes crossing each other.
A wavelength plate has been proposed (JP-A-5-100114).
According to this, a 1/4 wavelength phase difference can be given over a wide wavelength range. However, the phase difference characteristic is different between the front (vertical) and oblique directions. For example, when it is arranged on a reflective layer as a circularly polarizing plate and its antireflection property is examined, a black uniform It turned out to be a reflected color, but it turned out that there was a problem that a slightly bright blue or light yellow reflected color was obtained when the viewing angle was changed and the user looked obliquely.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a wave plate having a phase difference characteristic that is unlikely to be different between a front surface and a perspective while maintaining a feature that can function as a quarter wave plate over a wide wavelength region such as the entire visible light region. It is another object of the present invention to develop a circularly polarizing plate which is excellent in viewing angle characteristics because reflected light hardly causes a color difference between a front and a perspective, and which is excellent in antireflection broadband property and heat resistance.

[0005]

According to the present invention, a stretched film that gives a phase difference of に 対 し て wavelength to a monochromatic light and a stretched film that gives a phase difference of ４ wavelength are laminated with their optical axes crossing each other. And at least one of the stretched films has a photoelastic coefficient of 50 × 1/10 ^{13 with} respect to light having a wavelength of 633 nm.
cm ² / dyn or less, the wavelength dependence of the birefringence differences Δn ₁ and Δn ₂ is Δn ₁ / Δn ₂ <1 based on light having wavelengths of 400 nm (Δn ₁ ) and 550 nm (Δn ₂ ). .05, a quarter-wave plate, a circularly-polarized plate comprising a laminate of the quarter-wave plate and a polarizing plate, and having the circularly-polarized plate A liquid crystal display device characterized by the following.

[0006]

The birefringence difference (Δn) is obtained by laminating a plurality of stretched films that give a phase difference of １ ／ wavelength and １ ／ wavelength to monochromatic light with their optical axes crossing each other. )
The wavelength dispersion of the phase difference defined by the product of the thickness and the thickness (d) (△ nd) can be arbitrarily controlled by superimposing or adjusting the chromatic dispersion, thereby suppressing the chromatic dispersion while controlling the overall phase difference to a predetermined value. Thus, it is possible to obtain a wave plate exhibiting a 1/4 wavelength phase difference over a wide wavelength range such as the entire visible light range.

In the above case, the photoelastic coefficient for light having a wavelength of 633 nm is 50 × 1/10 ¹³ cm ² / dyn or less, and the wavelength dependence of the birefringence differences Δn ₁ and Δn ₂ is 400 nm (Δn 2).
n ₁₎ and on the basis of the wavelength of _{550nm (△ n 2) △ n} 1 /
By using a stretched film satisfying Δn ₂ <1.05, it has excellent heat resistance, has little difference in retardation characteristics between the front and the oblique, and functions as a 波長 wavelength plate in a wide wavelength region such as a visible region. You can get things.

Further, by using the above-mentioned quarter wavelength plate, the reflected light is unlikely to cause a color difference between the front and the perspective, so that the viewing angle characteristic is excellent,
It is possible to obtain a circularly polarizing plate which is excellent as a broadband antireflection filter which is excellent in antireflection broadband properties and heat resistance and almost prevents reflection of light in a visible region or the like.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A quarter-wave plate according to the present invention comprises a stretched film giving a phase difference of 1/2 wavelength and a stretched film giving a phase difference of 1/4 wavelength to monochromatic light. At least one of the stretched films has a photoelastic coefficient of 50 × 1/10 ¹³ cm ² / dyn or less for light having a wavelength of 633 nm, a birefringence difference Δn ₁ ,
The wavelength dependence of Δn ₂ is 400 nm (Δn ₁ ) and 550 nm
It is composed of Δn ₁ / Δn ₂ <1.05 based on the light of (Δn ₂ ).

FIG. 1 shows an example of a quarter-wave plate according to the present invention. Reference numerals 1 and 3 are stretched films that give a retardation of １ ／ wavelength or １ ／ wavelength, and 2 is a transparent adhesive layer. The condition for obtaining the quarter-wave plate according to the present invention is that at least two types of stretched films that give a phase difference of 波長 wavelength and １ ／ wavelength to monochromatic light are used, and at least one of the stretched films is used. The photoelastic coefficient for light having a wavelength of 633 nm is 50 × 1/10 ¹³ cm ² / dyn or less, and the birefringence difference Δ
The wavelength dependences of n ₁ and Δn ₂ are 400 nm (Δn ₁ ) and 550 n
△ n ₁ / △ n ₂ <1.05 based on m (光 n ₂ ) wavelength light
And crossing the optical axis of each stretched film to be laminated.

In the above, the number of layers of the stretched film is arbitrary. Generally, two to five sheets are stacked in terms of light transmittance and the like. Further, the arrangement positions of the stretched film that gives a retardation of １ ／ wavelength and the stretched film that gives a retardation of 波長 wavelength are also arbitrary.

[0012] As an example, a case where one stretched film giving a phase difference of 1/4 wavelength is used and arranged at the exit side end of the 1/4 wavelength plate, the crossing angle of the optical axis of each stretched film and each stretched film are used. The relationship of the direction (θ) of polarized light leaving the stretched film is represented by the following equation. That is, assuming that the number of stretched films that give a half-wave retardation is n, they are λ / 2 (1, 2,
.. N), and the lamination angle of each λ / 2 (1, 2,... N) is θ ₁ , with the incident linear polarization direction as a reference (0 °).
Assuming θ ₂ ,... θ _n , the stacking angle = 2 (θ ₁ + θ ₂ +... + θ _n-1 ) + θ _n The direction of polarized light leaving each λ / 2 plate = 2 (θ ₁ + θ ₂ + ... +
θ _n ), a circularly polarized light can be obtained by laminating a stretched film having a phase difference of 波長 wavelength at an angle of 45 °.

The above relationship is shown in the following table, taking as an example the case where three stretched films (λ / 2 (1, 2, 3)) giving a retardation of 波長 wavelength are used. Here, λ / 4 represents a stretched film that gives a retardation of 波長 wavelength.

In the present invention, 1 is used for monochromatic light.
The stretched film giving a phase difference of wavelength or １ ／ wavelength can be obtained, for example, by a method of stretching a polymer film by an appropriate method such as uniaxial or biaxial. The type of the polymer is not particularly limited, and those having excellent transparency are preferably used. Examples include polycarbonate-based polymers and polyester-based polymers, polysulfone-based polymers and polyethersulfone-based polymers, polystyrene-based polymers and polyolefin-based polymers, polyvinyl alcohol-based polymers and cellulose acetate-based polymers, and polystyrene-based polymers. Examples include a vinyl chloride polymer, a polymethyl methacrylate polymer, a polyarylate polymer, and a polyamide polymer.

In particular, from the viewpoint of easy realization of the wavelength dependence of the photoelastic coefficient and the birefringence difference, polyolefin polymers, especially, cyclic olefin polymers and cellulose acetate polymers are preferred. And polymethyl methacrylate polymers can be preferably used. Also, such a polymer is １ ／
It can be particularly preferably used for forming a stretched film giving a wavelength retardation.

On the other hand, in the formation of a stretched film giving a half-wave retardation, the workability of giving the retardation,
Grant and 400nm high photoelastic coefficient (△ n ₁₎ and 550n
Based on the wavelength light of m (1n ₂ ), the birefringence index differences △ n ₁ , △ n ₂
For example, a polycarbonate-based polymer is preferred in terms of suppressing the difference in phase difference between the front and the oblique view by providing a property that the wavelength dependency of △ n ₁ / △ n ₂ > 1.05 satisfies, and further improving the viewing angle property. And polysulfone-based polymers, polyethersulfone-based polymers and polyarylate-based polymers can be particularly preferably used.

Therefore, as described above, from the viewpoint of obtaining a quarter-wave plate having excellent heat resistance and viewing angle characteristics, the wavelength is 633 nm.
A stretched film that gives a phase difference of 1/4 wavelength to monochromatic light satisfying Δn ₁ / Δn ₂ <1.05 with a photoelastic coefficient of 50 × 1/10 ¹³ cm ² / dyn or less for the light of , △ n ₁ /
It is preferable to use a combination with a stretched film that gives a half-wave retardation to monochromatic light satisfying Δn ₂ > 1.05.

A stretched film satisfying the photoelastic coefficient and Δn ₁ / Δn ₂ can be obtained by controlling the type of forming material, stretching conditions, and the like. From the viewpoint of improving heat resistance, the photoelastic coefficient for light having a wavelength of 633 nm is 50.
When the photoelastic coefficient is not more than × 1 × 10 ¹³ cm ² / dyn, the preferable photoelastic coefficient is not more than 40 × 1/10 ¹³ cm ² / dyn, especially 30 × 1.
/ 10 ¹³ cm ² / dyn or less, especially 20 × 10 ¹³ cm ² / dyn
It is as follows.

In addition, the above-mentioned Δn ₁ / Δn ₂ can be attained by suppressing a difference in phase difference in a specific wavelength range, particularly on the shorter wavelength side, from being satisfied with the phase difference characteristic of the 波長 wavelength plate. <
A preferable Δn ₁ / Δn ₂ (the same applies hereinafter) when 1.05 is satisfied is 0.95 to 1.04, particularly 0.97 to 1.0
3, especially 0.98 to 1.02.

On the other hand, △ n ₁ / △ n ₂
The preferred Δn ₁ / Δn ₂ when satisfying> 1.05 is:
1.06-5, especially 1.1-4, especially 1.15-3. The high photoelastic coefficient in the case of the above-mentioned stretched film giving a half-wave retardation is, for example, 60 × 10 ¹³ cm ² / dyn in view of the workability of giving the retardation.
More than 70 × 1/10 ¹³ cm ² / dyn, especially 80 ×
It is preferably at least 1/10 ¹³ cm ² / dyn.

Furthermore inhibition of difference of the phase difference in the wavelength dependence of the satisfiability or a specific wavelength range of the above-mentioned birefringence difference, from the viewpoint of prevention of coloration due to the viewing angle changes, (n _x -n _z ) /
As _{(n x -n y) = Nz} ( hereinafter the same), the formula: 0 ≦ Nz ≦
It is preferable to use a stretched film that satisfies 1. Incidentally n _x is the maximum refractive index in the plane in the formula, n _y is a refractive index in a direction perpendicular to n _x, is and n _z is the refractive index in the thickness direction. Therefore the above formula means a _{n y ≦ n z ≦ n x} . When it is necessary to control the refractive index in the thickness direction of the stretched film, it can be performed by, for example, a method of stretching a polymer film while bonding a heat-shrinkable film.

The circularly polarizing plate according to the present invention has the above-mentioned １ ／
It is obtained by laminating a wave plate and a polarizing plate. Figure 2 shows an example
It was shown to. 4 is a polarizing plate, 5 is a 1/4 wavelength plate, and 2 is a transparent adhesive layer. The circularly polarizing plate can be formed by crossing the polarizing plate (4) at the above-mentioned lamination angle,
It is preferable to laminate the polarizing plates at an angle such that the polarizing axis of the polarizing plate optimizes the front and oblique antireflection properties with respect to the optical axis of the stretched film exhibiting a phase difference of 波長 wavelength and １ ／ wavelength. . At this time, by changing the transmission axis (polarization axis) of the polarizing plate by 90 degrees, the direction of circularly polarized light (counterclockwise or clockwise circularly polarized light) can be converted.

In view of the anti-reflection characteristics and the viewing angle characteristics of the front and the oblique views, the quarter-wave plate which can be preferably used for forming a circularly polarizing plate is expressed by the following formula: It contains at least one stretched film satisfying ≦ Nz ≦ 0.7.

An appropriate polarizing plate can be used for forming the circularly polarizing plate, and there is no particular limitation. In general, a film obtained by adsorbing iodine and / or a dichroic dye on a film of a hydrophilic polymer such as a polyvinyl alcohol-based, partially formalized polyvinyl alcohol-based, or ethylene / vinyl acetate copolymer-based partially saponified product, polyvinyl A polarizing film composed of a polyene oriented film such as a dehydrated alcohol product or a dehydrochlorinated polyvinyl chloride product is used.

The thickness of the polarizing film is usually 5 to 80 μm, but is not limited to this. The polarizing plate may be one obtained by coating one or both sides of a polarizing film with a transparent protective layer or the like. Such a transparent protective layer or the like may have various purposes such as reinforcing the polarizing film, improving heat resistance, and protecting the polarizing film from humidity and the like. The transparent protective layer can be formed as a resin coating layer or a resin film laminate layer, and may contain fine particles for diffusion or surface roughening.

One or both of the anti-reflection layer 6 and the anti-glare treatment layer are preferably provided on one or both sides of the circularly polarizing plate from the viewpoint of preventing surface reflection as exemplified in FIG. It is preferable that a hard coat layer is provided from the viewpoint of surface protection and the like. Such an anti-reflection layer,
The polarizing plate may be provided with one or more layers of an antireflection layer, an antiglare treatment layer, and a hard coat layer, and the polarizing plate may be laminated with a quarter-wave plate.

The anti-reflection layer can be appropriately formed as, for example, a light coherent film such as a fluorine-based polymer coat layer or a multilayer metal vapor-deposited film. The anti-glare treatment layer is also finely divided by an appropriate method such as a method in which fine particles are dispersed and fixed to the surface of the circularly polarizing plate via a binder or a method in which the surface of the circularly polarizing plate is embossed, sandblasted, or etched. It can be formed by an appropriate method in which surface reflected light is diffused by a method of providing a concave-convex structure, a method of applying a transparent resin containing fine particles to provide a fine concave-convex structure on the surface, or a method of using them in combination. it can.
Further, the hard coat layer can be formed of an appropriate hard film made of, for example, a cured film of a silicone resin.

The fine particles for the antiglare treatment layer described above include:
For example, silica or calcium oxide having an average particle diameter of 0.5 to 20 μm, alumina or titania, zirconia or tin oxide, indium oxide or cadmium oxide, inorganic fine particles that may be conductive such as antimony oxide, or polymethyl methacrylate or One or more appropriate ones such as crosslinked or uncrosslinked organic fine particles made of an appropriate polymer such as polyurethane may be used.

Each layer such as a stretched film or a polarizing plate for forming a quarter-wave plate or a circularly polarizing plate according to the present invention may be in a separated state. It is preferable that a part, particularly, all of them are fixedly treated in order to prevent displacement and prevent invasion of foreign matter such as dust. For the fixing treatment, for example, an appropriate material such as a transparent adhesive can be used, and the kind of the adhesive and the like is not particularly limited. From the viewpoint of preventing a change in the optical properties of the constituent members, it is preferable that a high-temperature process is not required for curing and drying at the time of the bonding process, and that a long curing process and a drying time are not required. From such a point, an adhesive layer can be preferably used.

For the formation of the pressure-sensitive adhesive layer, for example, a transparent pressure-sensitive adhesive using an appropriate polymer such as an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyether or synthetic rubber can be used. Above all, acrylic pressure-sensitive adhesives are preferred from the viewpoints of optical transparency, adhesive properties, weather resistance and the like.

The pressure-sensitive adhesive layer which can be preferably used from the viewpoint of suppressing reflection at the lamination interface has a refractive index difference of 0.1 or less, particularly 0.08 or less, particularly 0.06 or less with respect to an object to be bonded such as a stretched film. These are: Adjustment of the refractive index of the adhesive layer
It can be carried out by the kind of the base polymer or the blending of the refractive index regulator. As the refractive index adjusting agent, for example, an appropriate one such as polymers having a higher or lower refractive index than the base polymer can be used.

Further, the pressure-sensitive adhesive layer can be preferably used because it is excellent in the function of relieving internal stress generated by heat inside the laminate based on its viscoelasticity and preventing photoelastic deformation. The pressure-sensitive adhesive layer that can be particularly preferably used from the viewpoint of preventing photoelastic deformation has excellent stress relaxation properties. Above all, the relaxation modulus is 2 × 10 ⁵ to 1 × 10 ⁷ dyne / cm ² , especially 2 × 1
0 ^6-8 adhesive layer × 10 ⁶ dyne / cm ² is preferred. 1
The adhesive layer provided as needed for the purpose of adhering to an adherend such as a liquid crystal cell on one or both sides of a 波長 wavelength plate or a circularly polarizing plate is also preferably an adhesive layer for the above-described reasons and the like.

The quarter wave plate and the circularly polarizing plate according to the present invention
It can be used for various applications such as antireflection filters, antiglare filters, and liquid crystal display devices such as liquid crystal projectors. A liquid crystal display device is generally formed by appropriately assembling components such as a polarizing plate, a liquid crystal cell, and a backlight, a reflecting plate, and a phase difference compensating plate as necessary, and incorporating a driving circuit. In the present invention, there is no particular limitation except that the above-described １ ／ wavelength plate or circularly polarizing plate is used, and a liquid crystal display device can be formed according to the related art.

In the above description, the circularly polarizing plate functions as a circularly polarized light forming plate by emitting circularly polarized light from the quarter-wave plate as described above when natural light enters from the polarizing plate side.
When circularly polarized light enters from the 波長 wavelength plate side, it is linearly polarized by the 波長 wavelength plate, and enters the polarizing plate to function as a linearly polarized light forming plate. Therefore, the circularly polarizing plate according to the present invention can be applied to a liquid crystal display device as the circularly polarized light forming functional plate, or can be applied to a liquid crystal display device as a linearly polarized light forming functional plate.

The former function as a circularly polarized light forming plate is useful as an anti-reflection filter for suppressing surface reflection of a liquid crystal display or the like. The latter function as a linearly polarized light forming plate is useful for forming a system for improving the brightness of a liquid crystal display device in combination with a backlight provided with a circularly polarized light forming plate made of cholesteric liquid crystal or the like. By using the circularly polarizing plate according to the present invention, a highly durable liquid crystal display device which is bright, has excellent contrast, has a wide viewing angle, and can be obtained.

In forming the liquid crystal display device, for example, a light diffusion plate, an antiglare layer, a prism sheet, an antireflection film, a protective layer, a protective plate, or a liquid crystal cell provided on a polarizing plate on the viewing side, or a liquid crystal cell and / or In addition, appropriate optical elements such as a phase difference compensating plate provided between the polarizing plates on the backlight side and an optical path control plate such as a prism sheet provided in the backlight can be appropriately arranged.

The components such as a quarter-wave plate and a circularly polarizing plate according to the present invention, a stretched film and a polarizing plate for forming a liquid crystal display device, and other components such as an adhesive layer, a light diffusion plate and a phase difference compensating plate are, for example, It may be one having an ultraviolet absorbing ability such as one treated with an ultraviolet absorbent such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex compound, or the like. Further, it is preferable that each component of the liquid crystal display device is also fixed and integrated via an adhesive layer or the like.

[0038]

Reference Example 1 A polycarbonate film having a refractive index of 1.59 and a thickness of 50 μm was stretched by 5% at 150 ° C., and a phase difference of 波長 wavelength with respect to light having a wavelength of 550 nm was determined based on birefringent light. The given photoelastic coefficient is 90 × 1/10 ¹³ cm ² / dyn, Δn ₁ / Δn ₂
Is 1.16, and a λ / 2 stretched film having an Nz of 0.5 is obtained.

Reference Example 2 A λ / 2 stretched film according to Reference Example 1 was obtained except that Nz was 1.

Reference Example 3 According to Reference Example 1, a stretching treatment condition of 2.5% was １ ／.
A λ / 4 stretched film having an Nz of 1 giving a wavelength retardation was obtained.

Reference Example 4 A cyclic polyolefin film having a refractive index of 1.51 and a thickness of 100 μm (ARTON, manufactured by JSR Corporation, hereinafter the same) was used for 17
The film is stretched by 25% at 5 ° C. and a wavelength of 55
The photoelastic coefficient that gives a phase difference of 1/4 wavelength to light of 0 nm is 4.1 × 1/10 ¹³ cm ² / dyn, and Δn ₁ / Δn ₂ is 1.
At 025, a λ / 4 stretched film with Nz of 1 was obtained.

Reference Example 5 A cyclic polyolefin film having a refractive index of 1.51 and a thickness of 100 μm was stretched at 175 ° C. by 50%, and a phase difference of 波長 wavelength with respect to light having a wavelength of 550 nm was determined based on birefringent light. The given photoelastic coefficient is 4.1 × 1/10 ¹³ cm ² / dyn, Δn
A λ / 2 stretched film having ₁ / Δn ₂ of 1.025 and Nz of 1 was obtained.

Example 1 The λ / 2 stretched film obtained in Reference Example 1 and the λ / 2
The 延伸 stretched films are laminated via an acrylic pressure-sensitive adhesive having a refractive index of 1.47 with their optical axes (stretched axes) crossing each other.
After obtaining a 波長 wavelength plate, an anti-glare polarizing plate (Nitto Denko Corporation, NPF-EG1425DUAG30ARS, manufactured by Nitto Denko Corporation) having an anti-reflection layer on the λ / 2 stretched film side via an acrylic adhesive.
The same applies hereinafter) to obtain a circularly polarizing plate. The crossing angle of the optical axis with respect to the polarization axis of the polarizing plate was 1 for a λ / 2 stretched film.
2 degrees, the λ / 4 stretched film is 69 degrees.

Comparative Example 1 A quarter-wave plate and a circularly polarizing plate were prepared in the same manner as in Example 1 except that the film obtained in Reference Example 2 was used instead of the film obtained in Reference Example 1 as a λ / 2 stretched film. I got

Comparative Example 2 The λ / 2 stretched film obtained in Reference Example 2 and the λ / 2
/ 4 stretched film, the crossing angle of the optical axis to the polarization axis of the polarizing plate is 17.5 degrees for the λ / 2 stretched film,
A 波長 wavelength plate and a circularly polarizing plate were obtained in the same manner as in Example 1 except that the λ / 4 stretched film was adjusted to 80 °.

Comparative Example 3 The λ / 2 stretched film obtained in Reference Example 5 and the λ / 2
A 波長 wavelength plate and a circularly polarizing plate were obtained in the same manner as in Example 1 except that a combination of a 延伸 stretched film was used.

Evaluation Test Broadband Property The circularly polarizing plates obtained in Examples and Comparative Examples were placed on a diffuse reflection plate, and the reflected color at the front was visually observed and evaluated according to the following criteria. Excellent: When the reflection color is black Bad: When the reflection color is blue Unsuitable: When the reflection color is bright and blue

Viewing Angle Characteristics The circularly polarizing plates obtained in the examples and comparative examples were placed on a diffuse reflector, and the reflection color and brightness at the front and at an angle of 45 ° were visually observed and evaluated according to the following criteria. Excellent: When there is no change in the reflection color and brightness between the front and the perspective. Poor: When the reflection color changes between the front and the perspective. Inappropriate: When the reflection color and the brightness change greatly between the front and the perspective.

Heat resistance The circularly polarizing plates obtained in Examples and Comparative Examples were bonded to a glass plate via an acrylic pressure-sensitive adhesive layer, heated to 70 ° C., and placed on a reflecting plate while maintaining the temperature to reflect light. Whether there is light coloring,
The color unevenness (color uniformity) was examined and evaluated according to the following criteria. Excellent: When there is no coloring and color unevenness Poor: When there is coloring and color unevenness

The results are shown in the following table.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a quarter-wave plate example.

FIG. 2 is a cross-sectional view of an example of a circularly polarizing plate.

FIG. 3 is a sectional view of another example of a circularly polarizing plate.

[Explanation of Signs] 5: 1/4 wavelength plate 1: Stretched film giving phase difference of 1/2 wavelength 3: Stretched film giving phase difference of 1/4 wavelength 4: Polarizing plate

Claims (6)

[Claims] 1. A stretched film which gives a phase difference of 波長 wavelength to a monochromatic light and a stretched film which gives a phase difference of ４ wavelength are laminated with their optical axes crossing each other, and said stretching is performed. At least one of the films has a photoelastic coefficient of 50 × 1/10 ¹³ cm ² / dyn or less for light having a wavelength of 633 nm;
The wavelength dependence of the birefringence index differences Δn ₁ and Δn ₂ is 400 nm.
Based on (△ n ₁ ) and 550 nm (△ n ₂ ) light, Δn ₁ /
1/4 characterized by Δn ₂ <1.05
Wave plate. _{2. The} stretched film according to claim 1, wherein said stretched film showing said photoelastic coefficient and said Δn ₁ / Δn ₂ is 1 to monochromatic light.
/ 4 is intended to provide a phase difference of the wavelength, the △ n ₁ of oriented films giving a retardation of 1/2 wavelength with respect to monochromatic light
/ A quarter-wave plate wherein Δn ₂ exceeds 1.05. 3. The method of claim 1 or 2, the maximum in-plane refractive index, respectively n _x direction of the refractive index and the thickness direction of the refractive index of the orthogonal thereto, when the n _y and n _z, wherein: 0 ≤
_{(N x -n z) / (} n x -n y) at least one reference quarter-wave plate comprising a stretched film satisfies ≦ 1. 4. The quarter wave plate according to claim 1, wherein:
A circularly polarizing plate comprising a polarizing plate or a laminate of a polarizing plate having at least one of an anti-reflection layer, an anti-glare treatment layer and a hard coat layer on the surface side with an adhesive layer interposed therebetween. 5. The method of claim 4, 1/4 maximum refractive index of the wave plate is a plane, each n _x direction of the refractive index and the thickness direction of the refractive index of the orthogonal thereto, when the n _y and n _z ,
_{Formula: 0.3 ≦ (n x -n z} ) / (n x -n y) ≦ 0.7 circularly polarizing plate are those containing at least one of the stretched film satisfies. 6. A liquid crystal display device comprising the circularly polarizing plate according to claim 4 or 5.