JP2001091951A - Reflective liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably provide a reflective liquid crystal display device with excellent display performance. SOLUTION: The reflective liquid crystal display device comprises a reflection plate 12, a liquid crystal cell 27 and a polarizing plate 30 laminated in this order and is provided with an optically anisotropic layer 28A which has >=150 nm and <=350 nm product of the oriented birefringence and the thickness measured at 550 nm wavelength and has a twisted structure, and an optically anisotropic layer 28B which has >=60 nm and <=170 nm retardation, between the reflection plate 12 and the polarizing plate 30. Because the layer 28 comprising the optically anisotropic layer 28A and the optically anisotropic layer 28B functions as a wide band quarter-wave plate, the wavelength dependence of the polarized light azimuth angle is reduced and the lowering of display contrast and the coloring are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display which can be used as a display device in various fields such as a personal computer, an AV device, a portable information communication device, a game and a simulation device, and a vehicle navigation system. Related to the device.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device has attracted attention because it does not require a backlight necessary for a transmission type liquid crystal display device, can reduce power consumption, and can be easily reduced in size and weight. I have. On the other hand, the reflection type liquid crystal display device has a problem that the brightness of display is affected by the brightness of ambient light, and various studies have been made for the purpose of improving the display contrast. For example, Japanese Patent Application Laid-Open No. 10-186357 proposes a reflective liquid crystal display device having a configuration using a λ / 4 plate. The reflection type liquid crystal display device described in the above publication uses a λ / 4 wavelength plate to reduce light attenuation and improve display contrast.

[0003]

The above-mentioned λ / 4
The plate is desirably a retardation plate having a function of converting linearly polarized light into circularly polarized light with respect to all incident light in the visible light region visible to human eyes. A retardation plate (broadband λ /) that functions as a λ / 4 plate for incident light in the entire visible light region.
As the four plates, for example, Japanese Patent Application Laid-Open Nos. 10-68816 and 10-90521 propose a retardation plate formed by laminating two polymer films having mutually different optical anisotropy. ing. However, the λ / 4
In order to produce a board, it is necessary to obtain two types of chips obtained by cutting a stretched film stretched in one direction at directions different from each other with respect to the stretching direction, and to bond and laminate these chips. In the retardation plate having the above configuration, the optical anisotropy (the inclination of the optical axis or the slow axis) of each polymer film is determined by the angle at which the chip is cut with respect to the stretching direction of the stretched film. Therefore, precise cutting technology is required. Also, when bonding two chips,
Adhesive must be applied and precise positioning is required.
The manufacturing process is complicated. In a simpler way, the broadband λ
If a quarter-plate can be manufactured, the performance of a reflection type liquid crystal display device having the same can be stabilized, and a reflection type liquid crystal display having good performance can be stably provided.

An object of the present invention is to solve the above-mentioned problems and stably provide a reflective liquid crystal display device having good display performance.

[0005]

In order to achieve the above object, a reflection type liquid crystal display device of the present invention is a reflection type liquid crystal display device in which a reflection plate, a liquid crystal cell and a polarizing plate are laminated in this order, 550n wavelength between the reflector and the polarizer
The product of the orientation birefringence and the thickness measured in m is 150 nm or more and 350 nm, and the optically anisotropic layer A having a twisted structure, and the retardation is 60 nm or more and 170 nm
The following optically anisotropic layer B was used.

In the reflection type liquid crystal display device of the present invention, the wavelength 5
The product of orientation birefringence and thickness measured at 50 nm is 150 n
m or more and 350 nm or less, an optically anisotropic layer A having a twisted structure, and a retardation value of 60 nm or more and 1
The linearly polarized light transmitted through the polarizing plate is converted into circularly polarized light by the broadband λ / 4 plate on which the optically anisotropic layer B of 70 nm or less is laminated. In particular, when the light is converted by the optically anisotropic layer A, the wavelength dependence of the polarization azimuth caused by the wavelength dispersion of the incident light is reduced by the twisted structure of the optically anisotropic layer A. It is possible to convert linearly polarized light in almost the entire visible light region into circularly polarized light. As a result, coloring and a decrease in contrast due to the wavelength dispersion of light incident on the liquid crystal cell are reduced, and high-contrast display is possible.

[0007] At least the optically anisotropic layer A (preferably both) of the optically anisotropic layers A and B used in the reflection type liquid crystal display device of the present invention is formed of liquid crystalline molecules.
The optically anisotropic layer composed of liquid crystal molecules is easier to adjust optical properties than a birefringent film composed of a polymer. It is easy to maintain display quality even in production and the like. The liquid crystal molecules are preferably discotic liquid crystal molecules. Further, the optically anisotropic layer A
It preferably has a twist angle of not less than 45 ° and not more than 45 °.

The optically anisotropic layer B may be composed of liquid crystalline molecules, and the optically anisotropic layer B may be a stretched polymer film.

When the optically anisotropic layers A and B are composed of liquid crystal molecules, it is preferable that the liquid crystal molecules are fixed in a substantially uniformly oriented state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing one embodiment of the reflection type liquid crystal display device of the present invention. Reflective liquid crystal display device 1
0 denotes a polarizing plate 30, a λ / 4 plate 28, and a liquid crystal cell 27.
And the reflection plate 12 are laminated. The liquid crystal cell 27 is configured such that a TN type liquid crystal layer 20 is filled between a front transparent substrate 26 and a back transparent substrate 14. ITO on the inside of the front substrate 26 and the inside of the back substrate 14
Electrode layers 16 and 24 made of a conductive film of (indium tin oxide) are formed, and by applying a voltage higher than the liquid crystal saturation voltage to the electrode layers 16 and 24, the liquid crystal molecules of the liquid crystal layer 20 become It is oriented perpendicular to the arrow x direction. When no voltage is applied, the liquid crystal molecules of the liquid crystal layer 20 are aligned by the alignment films 18 and 22 formed on the electrode layers 16 and 24 by the alignment r ₂ of the liquid crystal molecules at the interface of the alignment film 18 (FIG. 2). Then, the orientation r ₁ of the liquid crystalline molecules at the interface of the orientation film 22 (FIG. 2) is in a 45 ° twisted state. The polarizing plate 30 and the λ / 4 plate 28 are arranged outside the front transparent substrate 26 of the liquid crystal cell 27, and the reflection plate 12 is arranged outside the rear substrate 14 of the liquid crystal cell 27.

The λ / 4 plate 28 has a structure in which an optically anisotropic layer 28A and an optically anisotropic layer 28B are laminated. The optically anisotropic layer 28A is formed by applying and drying a coating solution containing liquid crystal molecules on an alignment film (not shown) formed on a transparent substrate (not shown). Are substantially uniformly oriented and the optically anisotropic layer 28
The orientation of the liquid crystalline molecules located at the interface with B and the interface with the polarizing plate 30 is twisted. That is, the optically anisotropic layer 28A
Has a twisted structure. On the other hand, the optically anisotropic layer 28
B is composed of a polymer film stretched in one direction. The product of the orientation birefringence measured at a wavelength of 550 nm and the thickness is 150 nm or more and 350 nm.
It is. Here, the product of the orientation birefringence and the thickness (hereinafter, referred to as the product).
The term “Re ′” means a value corresponding to the in-plane retardation value Re of the optically anisotropic layer 28 </ b> A having no twisted structure (twist angle of 0 °). The in-plane retardation value Re will be described later. On the other hand, the optically anisotropic layer 28B has a retardation of 60 nm or more and 170 nm or less.

FIG. 2 shows the positional relationship of each layer of the reflection type liquid crystal display device 10 shown in FIG. 1 together with the polarization axis, the slow axis and the like of each layer. Optically anisotropic layer 28A and optically anisotropic layer 28B
The optically anisotropic layer 28A and the polarizing plate 30 are arranged such that their slow axes a and b intersect on the same plane at 60 ° (= θ ₁ ).
Is such that the slow axis a and the polarizing axis p intersect on the same plane at 15 ° (= θ ₂ ), and the optically anisotropic layer 28B and the polarizing plate 30 have the slow axis b and the polarizing axis p. Are intersected at the same plane at 75 ° (= θ ₃ ). Further, the electrode 16
And when no voltage is applied to the liquid crystal layer 20
The alignment r ₂ of the liquid crystalline molecules at the interface of the alignment film 18 and the polarization axis p of the polarizing plate 30 are designed to be parallel to each other. The optically anisotropic layer 28 composed of liquid crystal molecules
The slow axis of A is determined by the orientation of the liquid crystal molecules, and is usually determined by the rubbing direction of the alignment film 29A. For the optically anisotropic layer 28A having a twisted structure, the slow axis cannot be defined in a strict sense, but here, it refers to the slow axis at the interface on the rubbing surface side.
The slow axis of the optically anisotropic layer 28B made of a stretched polymer film coincides with the stretching direction when the intrinsic birefringence is positive, and is orthogonal when the intrinsic birefringence is negative.

The monochrome display function of the reflection type liquid crystal display device 10 will be described below. First, a state in which no voltage is applied to the electrode layers 16 and 24 (white display) will be described. When light is incident on the polarizing plate 30, the incident light becomes linearly polarized light in the polarization axis direction p by the polarizing plate 30. This linearly polarized light is converted by the optically anisotropic layer 28A into one with respect to the polarization axis p.
The optical axis of the optically anisotropic layer 28A has an amplitude direction around an axis forming 5 °.
Only the retardation is converted. Here, the optically anisotropic layer 28A has a Re ′ of 15 when measured at a wavelength of 550 nm.
It is not less than 0 nm and 350 nm, and has a twisted structure. Therefore, the Re measured at a wavelength of 550 nm is within the above range, and the polarization generated by the wavelength dispersion of the linearly polarized light as compared with the case where linearly polarized light is incident on the optically anisotropic layer having no twist structure. The difference in azimuth has been reduced.

For example, assuming that Re measured at a wavelength of 550 nm is 275 nm and linearly polarized light is incident on an optically anisotropic layer having no twist structure, a linear light having a wavelength of 550 nm (green: G) is obtained. Polarized light is converted by the optically anisotropic layer into linearly polarized light having different polarization azimuths. On the other hand, in the optically anisotropic layer, even in the visible light region, the retardation of light having a wavelength of 650 nm (red: R) longer than 550 nm is reduced by 1 /.
The retardation of the light having a wavelength of 450 nm (blue: B), which is shorter than two wavelengths, is reduced by half.
When the wavelength is equal to or longer than the wavelength, both become elliptically polarized light.
Also, the polarization azimuth angles of R, G, and B do not match. This deviation of the polarization azimuth increases as the wavelength dispersion becomes larger, and even if a material having any wavelength dispersion characteristics is used for the optically anisotropic layer, the circularly polarized light in R, G, and B can be obtained. I can't get it.

On the other hand, the optically anisotropic layer 28A has a twist structure. As a result of various studies by the present inventor, it has been found that by providing a twisted structure to the optically anisotropic layer, the deviation of the polarization azimuthal angle due to wavelength dispersion can be reduced. Therefore, the linearly polarized light transmitted through the optically anisotropic layer 28A and the optically anisotropic layer 28B becomes a nearly perfectly circularly polarized light.

The liquid crystal molecules in the liquid crystal layer 20 are
Since no voltage is applied to the liquid crystal molecules 24 and 24, the liquid crystal molecules at the interface of the alignment film 18 are oriented in the r ₂ (FIG. 2B) direction, and the liquid crystal molecules at the interface of the alignment film 22 are oriented in the r ₁ direction. ing. The linearly polarized light that has passed through the polarizing plate 30 is converted into a λ / 4 plate 28
, And becomes circularly polarized light, and enters the liquid crystal cell 27. The circularly polarized light reaches the reflector 12 as linearly polarized light parallel to the polarization axis p by the liquid crystal molecules of the liquid crystal layer 20, is reflected by the reflector 12, and enters the liquid crystal cell 27 again. The incident linearly polarized light becomes circularly polarized light again by the liquid crystal layer 20, passes through the optically anisotropic layer 28B and the optically anisotropic layer 28A, is again converted into linearly polarized light parallel to the polarization axis p, and transmits through the polarizing plate 30. Then, a white display is obtained.

When a voltage higher than the liquid crystal saturation voltage is applied to the electrode layers 16 and 24 (black display), the liquid crystal molecules of the liquid crystal layer 20 are oriented in parallel to the direction of the arrow x in the drawing. In the same manner as described above, the linearly polarized light transmitted through the polarizing plate 30 is converted into circularly polarized light by the optically anisotropic layers 28A and 28B. When the liquid crystal molecules are oriented in parallel to the direction of the arrow x in the drawing, the optical anisotropy of the liquid crystal layer 20 is lost, so that the circularly polarized light is reflected by the reflection plate 12 as it is, and transmitted through the liquid crystal cell 27 as it is The light passes through the optically anisotropic layer 28B and the optically anisotropic layer 28A. That is, since the linearly polarized light passes through the λ / 4 plate 28 twice with the reflection plate 12 interposed therebetween before reaching the polarizing plate 30 again, the phase difference of the linearly polarized light is shifted by 90 ° and the reflection from the reflection plate 12 is reflected. Light does not pass through the polarizing plate 30, and a black display is obtained.

In this embodiment, the λ / 4 plate 28 is
Since a wide-band λ / 4 plate capable of coping with light having a wavelength in the visible light range is used, coloring of display due to wavelength dispersion can be reduced, and black-and-white display with high contrast can be performed. Also,
In the present embodiment, a pair of polarizing plates is used because the incident light passes through the polarizing plate and passes through the polarizing plate only twice before passing through the polarizing plate again during white display. The display is brighter than that of a reflective liquid crystal display device.

In the above embodiment, the λ / 4 plate 28
Is an optically anisotropic layer 28A composed of liquid crystal molecules,
Although the optical anisotropic layer 28B made of a stretched polymer film is laminated, the present invention is not limited to this.
The optically anisotropic layer 28B may also be composed of liquid crystal molecules. In this case, the alignment film of the optically anisotropic layer 28A and the alignment film of the optically anisotropic layer 28B are subjected to a rubbing treatment in a direction forming an angle of θ ₁ with each other, or
By configuring the alignment film with different materials, the slow axes a and b of the optically anisotropic layers A and B are
It can be designed to intersect at theta ₁ on the same plane. In some cases, the slow axis is orthogonal to the rubbing axis with respect to the rubbing direction. In such a case, the rubbing process is performed so as to form an angle of θ ₁ ± 90 °, so that the rubbing process is performed at the desired angle on the same plane. Can cross the slow axes a and b. Alternatively, a transparent polymer film may be disposed between the optically anisotropic layer 28A made of liquid crystal molecules and the optically anisotropic layer 28B, and both layers may be bonded. Thus, the optically anisotropic layer 28
It is preferable that the A and the optically anisotropic layer 28B be composed of liquid crystal molecules, because the production of a λ / 4 plate becomes easier and a reflective liquid crystal display device having good display performance can be more stably manufactured.

In the above embodiment, θ ₁ = 55 ° and θ ₂ =
Although the arrangement of each layer was designed with 15 °, θ ₃ = 70 °, and θ ₄ = 45 °, the present invention is not limited to this.

In the above embodiment, the optically anisotropic layer 28A
And 28B are arranged between the polarizing plate 30 and the liquid crystal cell 27, but the present invention is not limited to this arrangement, and the optically anisotropic layers 28A and 28B may be arranged between the reflector 12 and the liquid crystal cell. . Further, in the above-described embodiment, the configuration of the display device for black and white display has been described. However, for example, a color filter layer is disposed between the front transparent substrate 26 and the λ / 4 plate 28, Alternatively, a color filter layer may be formed to form a display device for color display. Further, in the above-described embodiment, the configuration of the reflection type liquid crystal display device including the TN type liquid crystal layer 20 has been described. However, the present invention is not limited to this. The driving of the liquid crystal cell may be a matrix driving or a segment driving, and the matrix driving may be a simple matrix driving method or an active matrix driving method.

Hereinafter, the optically anisotropic layer A and the optically anisotropic layer B constituting the reflection type liquid crystal display device of the present invention will be described. The product of the orientation birefringence measured at a wavelength of 550 nm and the thickness of the optically anisotropic layer A is 150 nm or more and 350 nm. R measured at a wavelength of 550 nm of the optically anisotropic layer A
e ′ is preferably 200 nm or more and 300 nm or less, and more preferably 230 nm or more and 275 nm or less. Further, the optically anisotropic layer A has a twist structure. The optically anisotropic layer is preferably composed of liquid crystalline molecules. It is preferable that the optically anisotropic layer A is composed of liquid crystal molecules because a twisted structure can be easily formed. When the optically anisotropic layer A is composed of liquid crystal molecules, the twisted structure has an orientation of the liquid crystal molecules,
It can be formed by continuously changing the thickness of the optically anisotropic layer A. The uppermost and lowermost liquid crystalline molecules of the optically anisotropic layer A are at least 3 °
Preferably, it is twisted by 5 ° or more. That is, the twist angle of the optically anisotropic layer A is preferably 3 ° or more and 45 ° or less, and more preferably 5 ° or more and 20 ° or less. Light in the visible light region converted by the optically anisotropic layer A, if the twist angle is in the above range, the polarization azimuth will be kept uniform in any wavelength light in the visible light region, Conversion to circularly polarized light by combination with the optically anisotropic layer 28B is facilitated.

The optically anisotropic layer B has a retardation of 6
An optically anisotropic layer having a thickness of 0 nm or more and 170 nm or less. The optically anisotropic layer B may have a retardation of 60 nm or more and 170 nm when light of a predetermined wavelength in the visible light region enters, and in particular, 550 n, which is an intermediate wavelength in the visible light region.
The retardation measured in m is preferably from 120 nm to 140 nm. In order to design the optically anisotropic layer to have a specific retardation when light of a specific wavelength (λ) is incident thereon, the in-plane retardation (Re) of the optically anisotropic layer can be adjusted. Good. Here, the in-plane retardation (Re) refers to an in-plane retardation value with respect to light incident from the normal direction of the optically anisotropic layer. Specifically, it is a value defined by the following equation. _{Re = (n x -n y)} × d In the formula, n _x and n _y represent the main refractive index in the plane of the optically anisotropic layer, d represents the thickness of the optically anisotropic layer (nm) .

The optically anisotropic layer B having the above-mentioned properties may be composed of a birefringent film or liquid crystalline molecules. In particular, the optically anisotropic layer B is composed of liquid crystalline molecules. preferable.

The birefringent polymer film can be produced by applying a treatment for expressing optical anisotropy to a usual polymer film. Examples of the polymer film include polyolefin (eg, polyethylene, polypropylene, norbornene-based polymer), polyvinyl chloride, polystyrene, polyacrylonitrile, polycarbonate, polysulfone, polyarylate, polyvinyl alcohol, polymethacrylate, polyacrylate, and polyacrylate. Examples include cellulose esters such as cellulose acetate and cellulose triacetate. Further, a polymer film composed of a copolymer or a polymer mixture of these polymers may be used.

In order to make the polymer film exhibit optical anisotropy, it is preferable to stretch the polymer film in a predetermined direction. The stretching is preferably uniaxial stretching. The uniaxial stretching is preferably longitudinal uniaxial stretching utilizing a peripheral speed difference between two or more rolls, or tenter stretching in which both sides of the polymer film are gripped and stretched in the width direction. Incidentally, the optical properties of the entirety of the two or more films may satisfy the above-described conditions by using two or more polymer films. When the intrinsic birefringence of the polymer used is positive, the direction in which the in-plane refractive index of the polymer film becomes the maximum is the direction in which the polymer film is stretched. On the other hand, when the intrinsic birefringence of the polymer used is negative, the direction in which the in-plane refractive index of the polymer film becomes maximum is the direction perpendicular to the direction in which the polymer film is stretched. The polymer film is preferably manufactured by a solvent casting method in order to reduce birefringence unevenness. Further, the thickness of the polymer film is preferably from 20 nm to 500 nm, more preferably from 50 nm to 200 nm, even more preferably from 50 nm to 100 nm.

The optically anisotropic layer A and the optically anisotropic layer B
It is preferably composed of liquid crystalline molecules. It is preferable to use liquid crystal molecules because optical adjustment becomes easy. For example, the optical direction of the optically anisotropic layer can be easily controlled by the rubbing direction of the alignment film. Furthermore, the Re value of the optically anisotropic layer composed of liquid crystal molecules can be strictly adjusted to a desired Re by adjusting the type and content of the liquid crystal molecules.

As the liquid crystal molecules, rod-shaped liquid crystal molecules or discotic liquid crystal molecules are preferable, and discotic liquid crystal molecules are particularly preferable. Examples of the rod-like liquid crystal molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, and alkoxy-substituted phenylpyrimidines. , Phenyldioxane, tolan and alkenylcyclohexylbenzonitrile are preferably used. Further, not only these low-molecular liquid crystal molecules but also high-molecular liquid crystal molecules can be used.

The discotic liquid crystalline molecules are described in various references (C. Destrade., Eta).
l. , Mo1. Crysr. Liq. Cryst. , V
ol. 71, page 111 (1981); edited by The Chemical Society of Japan, quarterly chemistry review, No. 22, Liquid Crystal Chemistry, Chapter 5,
Chapter 10, Section 2 (1994); Kohne et
al. Angew, Chem. Soc. Chem. C
omm. page 1794 (1985); Zha
ng et al. , J. et al. Am. Chem. Soc. ,
Vol. 116, page 2655 (1994)), and these discotic liquid crystal molecules can be widely used.

It is preferable that the discotic liquid crystal molecule has a polymerizable group, since the alignment state is easily maintained by a polymerization reaction. The polymerizable group is preferably introduced into the discotic core of the discotic liquid crystalline molecule via a linking group. That is, the discotic liquid crystalline molecule having a polymerizable group is preferably a compound represented by the following formula (I). General formula (I) D (-LP) _{n In the} general formula (I), D represents a discotic core, L represents a divalent linking group, P represents a polymerizable group, and n represents 4 More than 12
Represents the following integers.

In the general formula (I), as the discotic core represented by D, any of the skeletons of discotic liquid crystal molecules described in the above-mentioned documents and the like can be used. The structure of the discotic liquid crystalline molecule represented by the general formula (I), which specifically exemplifies the discotic core of D, is shown below. In each of the following structural formulas, LP (or P
L) means a combination of a divalent linking group (L) and a polymerizable group (P).

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

In the general formula (I), the divalent linking group (L) is selected from an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, -S- and a combination thereof. It is preferably a divalent linking group selected from the group consisting of: The divalent linking group (L) is an alkylene group, an alkenylene group, an arylene group, -CO-, -NH
More preferably, the group is a group obtained by combining at least two divalent groups selected from the group consisting of-, -O- and -S-. The divalent linking group (L) is most preferably a group obtained by combining at least two divalent groups selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO- and -O-. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms.
The arylene group preferably has 6 to 10 carbon atoms. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group, a halogen atom, a cyano, an alkyne group, an acyloxy group).

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is a polymerizable group (P).
To join. AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. L1: -AL-CO-O-AL- L2: -AL-CO-O-AL-O- L3: -AL-CO-O-AL-O-AL- L4: -AL-CO-O-AL- O-CO-L5: -CO-AR-O-AL-L6: -CO-AR-O-AL-O-L7: -CO-AR-O-AL-O-CO-L8: -CO-NH- AL-L9: -NH-AL-O-L10: -NH-AL-O-CO-L11: -O-AL-L12: -O-AL-O-L13: -O-AL-O-CO-

L14: -O-AL-O-CO-NH-AL- L15: -O-AL-S-AL- L16: -O-CO-AL-AR-O-AL-O-CO
-L17: -O-CO-AR-O-AL-CO- L18: -O-CO-AR-O-AL-O-CO- L19: -O-CO-AR-O-AL-O-AL- O-
CO-L20: -O-CO-AR-O-AL-O-AL-O-
AL-O-CO-L21: -S-AL-L22: -S-AL-O-L23: -S-AL-O-CO-L24: -S-AL-S-AL-L25: -S-AR -AL-

The polymerizable group (P) in the general formula (I) is determined according to the type of the polymerization reaction. Examples of the polymerizable group (P) are shown below.

[0039]

Embedded image

In the general formula (I), the polymerizable group (P) is
Unsaturated polymerizable groups (P1 to P7), epoxy groups (P8),
Or an azirdinyl group (P9),
It is more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group (P1 to P6).

In the general formula (I), n is 4 to 12
Represents an integer. The specific number is determined according to the type of the discotic core (D). The combination of a plurality of L and P may be different, but is preferably the same.

When the optically anisotropic layer A and / or the optically anisotropic layer B are composed of discotic liquid crystalline molecules,
Two or more discotic liquid crystal molecules may be used in combination. For example, the optically anisotropic layer A may be composed of discotic liquid crystal molecules having an asymmetric carbon atom in a divalent linking group and discotic liquid crystal molecules not having the same. Further, the optically anisotropic layer A and / or the optically anisotropic layer B may be composed of discotic liquid crystal molecules having a polymerizable group and discotic liquid crystal molecules not having the same.

As the discotic liquid crystal molecule having no polymerizable group (non-polymerizable discotic liquid crystal molecule), the polymerizable group (P) of the compound represented by the above general formula (I) may be a hydrogen atom or Compounds modified with an alkyl group are preferred. The non-polymerizable discotic liquid crystalline molecule is preferably a compound represented by the following general formula (II). General formula (II) D (-LR) _{n In the} above general formula (II), D represents a discotic core, L represents a divalent linking group, R represents a hydrogen atom or an alkyl group, and n Represents an integer of 4 to 12.

In the general formula (II), examples of the discotic core (D) include those similar to the specific examples of the discotic core of the general formula (I). Incidentally, in the structural formula of the exemplified compound,
LP (or PL) is replaced by LR (or RL). Further, the divalent linking group of the general formula (II) is the same as that of the general formula (I), and preferred examples are also the same. In the general formula (II), the alkyl group represented by R preferably has 1 to 40 carbon atoms,
More preferably, it is 0. The alkyl group may be a cyclic alkyl group or a chain alkyl group, but is more preferably a chain alkyl group, and among the chain alkyl groups, has no branch, Is more preferred. R is a hydrogen atom or a group having 1 to 1 carbon atoms.
It is preferably 30 linear alkyl groups.

When the optically anisotropic layer A is composed of discotic liquid crystalline molecules, a twist structure can be easily formed by introducing an asymmetric carbon atom into the discotic liquid crystalline molecules. For example, when the compound represented by the general formula (I) or the general formula (II) is used as the discotic liquid crystal molecule, it is preferable to introduce an asymmetric carbon into the divalent linking group L. In particular, when the divalent linking group is A
It is preferred to be L (alkylene group or alkenylene group) and introduce an asymmetric carbon atom into AL. Examples of AL containing an asymmetric carbon atom (AL ^* ) are shown below. The left end is the site where the discotic core (D) is bonded, and the right end is the site where the polymerizable group (P) is bonded. The carbon atom (C) marked with * is an asymmetric carbon atom. The optical activity of AL ^* may be either S or R.

[0046] ^{_{AL * 1: -CH 2 CH 2}} -C * HCH 3 -C
_{H 2 CH 2 CH 2 - AL} * 2: -CH 2 CH 2 CH 2 -C * HCH 3 -CH 2 CH 2
_{^{- AL * 3: -CH 2 -C}} * HCH 3 -CH 2 CH 2 CH 2 CH 2
^{- AL * 4: -C * HCH} 3 -CH 2 CH 2 CH 2 CH 2 CH 2 - AL * 5: -CH 2 CH 2 CH 2 CH 2 -C * HCH 3 -CH 2
_{^{- AL * 6: -CH 2 CH}} 2 CH 2 CH 2 CH 2 -C * HCH 3 - AL * 7: -C * HCH 3 -CH 2 CH 2 CH 2 CH 2 - AL * 8: -CH 2 -C ^{_{* HCH 3 -CH 2 CH 2 CH}} 2 - AL * 9: -CH 2 CH 2 -C * HCH 3 -CH 2 CH 2 - AL * 10: -CH 2 CH 2 CH 2 -C * HCH 3 -CH 2 _{^{- AL * 11: -CH 2 CH}} 2 CH 2 CH 2 -C * HCH 3 - AL * 12: -C * HCH 3 -CH 2 CH 2 CH 2 - AL * 13: -CH 2 -C * HCH 3 - ^{_{CH 2 CH 2 - AL * 14}} : -CH 2 CH 2 -C * HCH 3 -CH 2 - AL * 15: -CH 2 CH 2 CH 2 -C * HCH 3 - AL * 16: -CH 2 -C * ^{_{HCH 3 - AL * 17: -C}} * HCH 3 -CH 2 - AL * 18: -C * HCH 3 -CH 2 CH 2 CH 2 CH 2 CH 2 C
^{_{H 2 - AL * 19: -CH}} 2 -C * HCH 3 -CH 2 CH 2 CH 2 CH 2
^{_{CH 2 - AL * 20: -CH}} 2 CH 2 -C * HCH 3 -CH 2 CH 2 CH 2
^{_{CH 2 - AL * 21: -CH}} 2 CH 2 CH 2 -C * HCH 3 -CH 2 CH 2
^{_{CH 2 - AL * 22: -C}} * HCH 3 -CH 2 CH 2 CH 2 CH 2 CH 2 C
^{_{H 2 CH 2 - AL * 23}} : -CH 2 -C * HCH 3 -CH 2 CH 2 CH 2 CH 2
^{_{CH 2 CH 2 - AL * 24}} : -CH 2 CH 2 -C * HCH 3 -CH 2 CH 2 CH 2
^{_{CH 2 CH 2 - AL * 25}} : -CH 2 CH 2 CH 2 -C * HCH 3 -CH 2 CH 2
^{_{CH 2 CH 2 - AL * 26}} : -C * HCH 3 - (CH 2) 8 - AL * 27: -CH 2 -C * HCH 3 - (CH 2) 8 - AL * 28: -CH 2 -C * _{H (C 2 H 5) -} AL * 29: -CH 2 -C * H (C 2 H 5) -CH 2 - AL * 30: -CH 2 -C * H (C 2 H 5) -CH 2 CH ₂ −

[0047] _{^{AL * 31: -CH 2 -C *}} H (C 2 H 5) -C
_{H 2 CH 2 CH 2 CH 2} - AL * 32: -CH 2 -C * H (n-C 3 H 7) -CH 2 CH 2
_{^{- AL * 33: -CH 2 -C}} * H (n-C 3 H 7) -CH 2 CH 2
^{_{CH 2 CH 2 - AL * 34}} : -CH 2 -C * H (OCOCH 3) -CH 2 CH 2
_{^{- AL * 35: -CH 2 -C}} * H (OCOCH 3) -CH 2 CH 2
^{_{CH 2 CH 2 - AL * 36}} : -CH 2 -C * HF-CH 2 CH 2 - AL * 37: -CH 2 -C * HF-CH 2 CH 2 CH 2 CH 2 - AL * 38: -CH 2 _{^{-C * HCl-CH 2 CH 2}} - AL * 39: -CH 2 -C * HCl-CH 2 CH 2 CH 2 CH 2
_{^{- AL * 40: -CH 2 -C}} * H (OCH 3) -CH 2 CH 2 - AL * 41: -CH 2 -C * H (OCH 3) -CH 2 CH 2 CH
^{_{2 CH 2 - AL * 42:}} -CH 2 -C * HCN-CH 2 CH 2 - AL * 43: -CH 2 -C * HCN-CH 2 CH 2 CH 2 CH 2
_{^{- AL * 44: -CH 2 -C}} * HCF 3 -CH 2 CH 2 - AL * 45: -CH 2 -C * HCF 3 -CH 2 CH 2 CH 2 CH 2
−

By adding a compound (chiral agent) having an optical activity containing an asymmetric carbon atom to the optically anisotropic layer A, the optically anisotropic layer A can have a twisted structure. As the compound containing an asymmetric carbon atom, various natural or synthetic compounds can be used. A polymerizable group may be introduced into a compound containing an asymmetric carbon atom. Introducing a polymerizable group is preferable because the chiral agent can be fixed to the optically anisotropic layer, and the twist structure of the optically anisotropic layer A can be more easily adjusted. Hereinafter, examples of the chiral agent will be described. In the following exemplified compounds, C-1, C-3 and C
-4 is a left-handed chiral agent, C-2 and C-
5 is a right-handed chiral agent.

[0049]

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[0050]

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When the optically anisotropic layers A and B are composed of discotic liquid crystalline molecules, if the optically anisotropic layers contain cellulose ester, the orientation of the liquid crystalline molecules is substantially uniform even on the air interface side. It is preferable because it can be oriented. As the cellulose ester, a cellulose ester of a lower fatty acid having 6 or less carbon atoms is preferable. The lower fatty acid preferably has 2 to 5 carbon atoms, and more preferably 2 to 4 carbon atoms. The lower fatty acid may have a substituent such as a hydroxy group. Further, an ester of cellulose with two or more different fatty acids may be used. Preferred examples of the cellulose ester include cellulose ester, cellulose propionate, cellulose butyrate, cellulose hydroxypropionate, cellulose butyrate, cellulose hydroxypropionate, cellulose acetate propionate, and cellulose acetate butyrate. Can be The butyrylation degree of the cellulose acetate butyrate is preferably 30% or more,
More preferably, it is 30 to 80%. The acetylation degree of the cellulose acetate butyrate is 30%.
It is preferably the following, more preferably 1 to 30%.

The cellulose ester is contained in the optically anisotropic layer A or the optically anisotropic layer B in an amount of 0.005 to 0.5 g /
It is preferably m ^2, and more preferably from 0.01~0.45g / m ^2, more preferably from 0.02~0.4g / m ^2, 0.03~0.35g / Most preferably, it is m ² . Further, the content of the cellulose ester is 0.1% with respect to the content of the discotic liquid crystalline molecules contained in both the optically anisotropic layers A and B.
It is preferably from 1 to 5% by weight.

When the optically anisotropic layer A and the optically anisotropic layer B are composed of liquid crystalline molecules, a coating liquid containing a liquid crystalline polymer, if desired, the above-mentioned chiral agent, cellulose ester, and the following polymerization initiator Is prepared, applied to an alignment film, and dried. As a solvent used for preparing the coating solution, an organic solvent is preferable. As the organic solvent, amides (eg, N, N-
Dimethylformamide), sulfoxide (eg, dimethylsulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg, chloroform, dichloromethane), ester (eg, methyl acetate, butyl acetate) ), Ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane).
Among them, alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination as a solvent for the coating liquid.

The coating solution can be applied onto the alignment film by an extrusion coating method, a direct gravure loading method, a reverse gravure coating method, a die coating method, or the like.

It is preferable that the total thickness of the optically anisotropic layer A and the optically anisotropic layer B is smaller. Although it is difficult to reduce the thickness to less than 120 μm by laminating the polymer films, the total thickness of the optically anisotropic layer A and the optically anisotropic layer B is 10 μm.
μm or less.

When the optically anisotropic layers A and B are composed of liquid crystalline molecules, it is preferable that the liquid crystalline molecules are substantially uniformly aligned in the optically anisotropic layer. When discotic liquid crystal molecules are used as the liquid crystal molecules,
Preferably, the discotic liquid crystal molecules are vertically aligned. Further, it is preferable to fix the vertically aligned discotic liquid crystal molecules because the alignment state is more easily maintained. The immobilization is performed using a liquid crystal molecule into which a polymerizable group (P) is introduced as a liquid crystal molecule (in the case of using a discotic liquid crystal molecule as the liquid crystal molecule, the compound represented by the general formula (I)). It is preferable that the polymerizable group P is subjected to a polymerization reaction after it is oriented on the alignment film. The polymerization can be performed by a thermal polymerization reaction using a thermal polymerization initiator or a photopolymerization reaction using a photopolymerization initiator. Among them, a photopolymerization reaction is preferable.

As the photopolymerization initiator, α-carbonyl compounds (U.S. Pat. Nos. 2,367,661 and 236,767)
0), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. No. 3,046,127)
No. 2,951,758), a combination of a triarylimidazole dimer and p-aminophenylketone (described in US Pat. No. 3,549,367), an acridine and phenazine compound (Japanese Unexamined Patent Publication No.
-105667, U.S. Pat. No. 4,239,850), and oxadiazole compounds (U.S. Pat.
No. 212970). The amount of the photopolymerization initiator used is from 0.01 to 20% of the solid content of the coating solution.
%, More preferably 0.5 to 5% by weight.

When the compound represented by the general formula (I) is polymerized with a photopolymerization initiator, it is preferable to use ultraviolet rays for light irradiation for starting the polymerization. The light irradiation energy for initiating polymerization is 20 mJ / cm ² -5
0 J / cm ² , preferably 100 to 800 mJ
/ Cm ² is more preferable. Light irradiation may be performed under heating conditions to promote the photopolymerization reaction.
The details of the polymerization are described in JP-A-8-58375,
JP-A-8-27284, JP-A-8-334621,
It is described in JP-A-9-104656.

When the optically anisotropic layers A and B are composed of liquid crystalline molecules, it is preferable to align the liquid crystalline molecules on the alignment film. In particular, when discotic liquid crystal molecules are used, it is preferable to substantially vertically align them on the alignment film. Here, “substantially vertical alignment” means that liquid crystal molecules are aligned at an average tilt angle of 60 to 90 °. In the case of discotic liquid crystal molecules, the tilt angle of the liquid crystal molecules refers to the angle between the disc surface and the alignment film, and in the case of the rod-shaped liquid crystal molecules, the angle between the rod surface and the alignment film. It is preferable to lower the surface energy of the alignment film because liquid crystal molecules are easily aligned vertically. The alignment film is usually made of a polymer, but the surface energy of the alignment film can be reduced by, for example, introducing a predetermined functional group into a polymer constituting the alignment film. As the functional group that lowers the surface energy of the alignment film, a hydrocarbon group having 10 or more carbon atoms is effective. In order to make the hydrocarbon group exist on the surface of the alignment film, it is preferable to introduce the hydrocarbon group into a side chain rather than the main chain of the polymer. The orientation of the liquid crystalline molecules is adjusted according to the required direction of the slow axis of the optically anisotropic layer. When a discotic liquid crystal is used, the liquid crystal is homogeneously oriented so that the director of the liquid crystal is directed to the slow axis of the polymer film. When a rod-shaped liquid crystal is used, the liquid crystal is made to have a homogeneous orientation in which the director is oriented in a direction orthogonal to the slow axis of the polymer film.

The hydrocarbon group includes an aliphatic group, an aromatic group, and a combination thereof. The aliphatic group is preferably an alkyl group (may be a cycloalkyl group) or an alkenyl group (may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not show strong hydrophilicity, such as a halogen atom. The number of carbon atoms of the hydrocarbon group,
It is preferably from 10 to 100, more preferably from 10 to 60, and most preferably from 10 to 40.

The main chain of the polymer constituting the alignment film is
It is more preferable to have a polyimide structure or a polyvinyl alcohol structure because liquid crystal molecules tend to be vertically aligned. The polyimide can be generally synthesized by a condensation reaction between a tetracarboxylic acid and a diamine. A polyimide corresponding to a copolymer may be synthesized using two or more kinds of tetracarboxylic acids or two or more kinds of diamines. The hydrocarbon group may be present in a repeating unit derived from a tetracarboxylic acid, may be present in a repeating unit derived from a diamine, or may be present in both repeating units. When a hydrocarbon group is introduced into a polyimide, it is particularly preferable to form a steroid structure in the main chain or side chain of the polyimide. The steroid structure present in the side chain corresponds to a hydrocarbon group having 10 or more carbon atoms, and has a function of vertically aligning discotic liquid crystalline molecules. In the present specification, the steroid structure is
A cyclopentanohydrophenanthrene ring structure or a ring structure in which a part of the bond of the ring is a double bond in the range of an aliphatic ring (range in which an aromatic ring is not formed).

When it is desired to vertically align liquid crystal molecules, it is preferable to use a modified polyvinyl alcohol having a hydrocarbon group having 10 or more carbon atoms as the alignment film. The hydrocarbon group is an aliphatic group, an aromatic group, or a combination thereof. The aliphatic group may be cyclic, branched, or linear. The aliphatic group is preferably an alkyl group (may be a cycloalkyl group) or an alkenyl group (may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not show strong hydrophilicity, such as a halogen atom. The hydrocarbon group preferably has 10 to 100 carbon atoms.
It is more preferably from 60 to 60, and most preferably from 10 to 40. The modified polyvinyl alcohol having a hydrocarbon group preferably contains 2 to 80 mol%, and more preferably 3 to 70 mol%, of a repeating unit having a hydrocarbon group having 10 or more carbon atoms.

The modified polyvinyl alcohol having a hydrocarbon group having 10 or more carbon atoms is represented by the following formula (PV). (PV)-(VA1) _x- (HyC) _y- (VAc) _{z- In the} formula (PV), VA1 represents a vinyl alcohol repeating unit, and HyC represents a hydrocarbon group having 10 or more carbon atoms. VAc represents a repeating unit of vinyl acetate. x is 20 to 95 mol% (preferably 25 to 90 mol%), y is 2 to 80 mol% (preferably 3 to 70 mol%), and z is 0 to 3 mol%.
0 mol% (preferably 2 to 20 mol%).

In the formula (PV), specific examples of (HyC), (HyC-I) and (HyC-II) are shown below.

[0065]

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In (HYC-I), L ¹ represents —O—, —C
_{O -, - SO 2 -,} - NH-, an alkylene group, an arylene group, and divalent linking group selected from their combinations. In (HYC-II), L ² is a single bond or a divalent linking group selected from —O—, —CO—, —SO ₂ —, —NH—, an alkylene group, an arylene group, and a combination thereof. Represents In (HYC-I) and (HYC-II), R ¹ and R ² each represent a hydrocarbon group having 10 or more carbon atoms.

Examples of divalent linking groups which can be L ¹ and L ² (L1 to L9) are shown below. L1: -O-CO- L2: -O -CO- alkylene group -O- L3: -O-CO- alkylene group -CO-NH- L4: -O-CO- alkylene group -NH-SO ₂ - arylene -O-L5: -arylene group-NH-CO- L6: -arylene group -CO-O-L7: -arylene group -CO-NH-L8: -arylene group -O-L9: -O-CO-NH- Arylene group -NH-CO-

The degree of polymerization of the polymer used for the alignment film is as follows:
200 to 5000, preferably 300 to 300
More preferably, it is 0. The weight average molecular weight of the polymer is preferably from 9000 to 200,000,
More preferably, it is 13000 to 130,000.
In addition, even if the alignment film is made of one kind of polymer,
It may be composed of more than two kinds of polymers.

It is preferable that the alignment film has been subjected to a rubbing treatment. The rubbing treatment can be performed by rubbing the surface of the film containing the polymer several times with paper or cloth in a certain direction. Incidentally, after the discotic liquid crystal molecules are vertically aligned using the alignment film, the discotic liquid crystal molecules are fixed to form an optically anisotropic layer,
Only the optically anisotropic layer may be transferred onto a polymer film (or a transparent support). According to this method, the discotic liquid crystal molecules in the vertical alignment state transferred to the polymer film or the like can maintain the alignment state without the alignment film. Therefore, when the optically anisotropic layers A and B are composed of liquid crystalline molecules, the alignment film is not an essential component.

The optically anisotropic layers A and B may have a structure laminated on a support. The support is preferably a transparent support. Here, the transparent support refers to a support having a light transmittance of 80% or more. The support preferably has a small wavelength dispersion and a small optical anisotropy.
The wavelength dispersion is the ratio of Re400 to Re700 (Re400
/ Re700) can be expressed as an index. Specifically, the ratio of Re400 / Re700 is preferably less than 1.2. The optical anisotropy can be represented by using Re as an index. Specifically, Re is preferably 20 nm or less, more preferably 10 nm or less.

As the support, a polymer film can be preferably used. As the polymer film, cellulose ester, polycarbonate, polysulfone,
A polymer film made of polyether sulfone, polyacrylate, polymethacrylate, or the like is preferable.
Above all, a polymer film of cellulose ester is preferable, a polymer film of acetyl cellulose is more preferable, and a polymer film of triacetyl cellulose is most preferable. The polymer film is preferably formed by a solvent casting method. The thickness of the support is preferably 20 to 500 μm,
More preferably, it is 0 to 200 μm. further,
An adhesive layer (undercoat layer) for adhering the alignment film and the support may be provided on the support. Further, in order to improve the adhesion between the support and a layer provided thereon (adhesive layer, alignment film, or optically anisotropic layer), the support is subjected to a surface treatment (eg, glow discharge treatment, corona discharge). Treatment, ultraviolet (UV) treatment, flame treatment).

The polarizing plate used in the reflection type liquid crystal display device of the present invention may be any of an iodine polarizing plate, a dye polarizing plate using a dichroic dye, and a polyene polarizing plate. In general, an iodine-based polarizing plate and a dye-based polarizing plate can be produced by stretching a polyvinyl alcohol-based film and adsorbing iodine or a dichroic dye thereon.
In this case, the polarization axis of the polarizing plate is a direction perpendicular to the film stretching direction. The polarizing plate may include a protective layer. The protective layer is preferably made of a material having high optical isotropy. As the protective layer, for example, it is preferable to use a cellulose S film, particularly a triacetyl cellulose film. Further, the protective layer may be integrally formed with a member constituting the optically anisotropic layer A or the optically anisotropic layer B. For example, when the transparent support of the optically anisotropic layer A is Alternatively, the optically anisotropic layer B made of a polymer film may function as a protective layer of the polarizing plate. Such a configuration is preferable because the polarizing plate and the λ / 4 plate (optically anisotropic layers A and B) can be bonded to each other by roll-to-roll, and the production becomes easier.

[0073]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited by the following examples. Circularly polarizing plates 1 to 4 each composed of a λ / 4 plate 28 and a polarizing plate 30, which are components of the reflection type liquid crystal display device 10 shown in FIG. 1, were manufactured as follows. [Preparation of Circularly Polarizing Plate 1] On a surface of an optically isotropic triacetyl cellulose film having a thickness of 100 μm and a width of 500 nm, a coating solution having the following composition was applied using a bar coater.
After drying at 30 ° C. for 3 minutes, an alignment film having a thickness of 0.5 μm was formed. Composition of coating liquid for forming alignment film Steroid-modified polyamic acid 5.0% by weight N-methyl-2-pyrrolidone 25.0% by weight Ethylene glycol monobutyl ether 25.0% by weight Methyl ethyl ketone 45.0% by weight

After performing a rubbing treatment on the formed alignment film, a coating solution having the following composition is applied on the alignment film, dried, and further irradiated with ultraviolet rays for 1 second at an irradiation energy of 500 mW / cm ² using a mercury lamp. By irradiating the optically anisotropic layer 28
A was formed. Coating solution for forming optically anisotropic layer 28A Discotic liquid crystal molecules (1) 32.6% by weight Cellulose acetate butyrate 0.2% by weight Modified trimethylolpropane triacrylate 3.2% by weight Sensitizer below 0.4% by weight Photopolymerization initiator below 1.1% by weight Chiral agent C-2 0.35% by weight Methyl ethyl ketone 62.5% by weight

[0075]

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[0076]

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Next, the produced optically anisotropic layer 28A was bonded with the polarizing plate 30 and the support of the optically anisotropic layer 28A facing each other. Lamination is performed so that the polarization transmission axis p of the polarizing plate 30 and the rubbing axis a of the optically anisotropic layer 28A form an angle of 15 °, thereby producing a laminate of the polarizing plate 30 and the optically anisotropic layer 28A. did. Next, one side of the optically anisotropic layer 28A (the surface on the side where the polarizing plate is not bonded) has a wavelength of 55 nm.
In-plane retardation (Re) at 0 nm is 137
A polycarbonate film having a thickness of nm was laminated. The angle between the transmission axis p of the polarizing plate 30 and the rubbing direction of the optically anisotropic layer 28A is 15 °, the angle between the transmission axis p of the polarizing plate 30 and the slow axis of the optically anisotropic layer 28B is 70 °, Anisotropic layer 2
The layers were laminated such that the angle between the rubbing direction of 8A and the slow axis of the optically anisotropic layer 28B was 55 °. Thus, a laminated body of the polarizing plate 30 and the λ / 4 plate 28 (hereinafter, this laminated body is referred to as a circularly polarizing plate 1) was produced.

[Preparation of Circular Polarizing Plate 2] In the preparation of the circular polarizing plate 1, the amount of the chiral agent C-2 used for preparing the coating liquid for forming the optically anisotropic layer 28A was reduced to 0.02% by weight. A circularly polarizing plate 2 was produced in the same manner as the circularly polarizing plate 1 except that the optically anisotropic layer 28A 'was changed. [Production of Circularly Polarizing Plate 3]
Circularly polarized light except that the amount of the chiral agent C-2 used for preparing the coating liquid for forming the optically anisotropic layer 28A was changed to 0.05% by weight to form the optically anisotropic layer 28A ″. Circularly polarizing plate 3 was produced in the same manner as plate 1. [Production of Circularly Polarizing Plate 4]
Circularly polarized light was formed in the same manner as in the circularly polarizing plate 1 except that the chiral agent C-2 used for preparing the coating liquid for forming the optically anisotropic layer 28A was not added, and the optically anisotropic layer 28A ″ ′ was formed. Plate 4 was produced.

The twist angles of the optically anisotropic layers 28A to 28A '''of the circularly polarizing plates 1 to 4 were determined.
The twist angle was measured using an ellipsometer (“M-1500”, manufactured by JASCO Corporation) equipped with a total reflection prism while rotating each sample of the optically anisotropic layers 28A to 28A ′ ″. The liquid crystal alignment direction was measured from the change in phase difference near the air interface, and each was determined from the difference from the rubbing axis.
FIG. 3 shows the relationship between the determined twist angle and the amount of the chiral agent C-2 added for the optically anisotropic layers 28A to 28A ″ ′. From the results shown in FIG. 3, by changing the amount of addition of the chiral agent C-2, the optically anisotropic layers 28A, 28
It has been demonstrated that the twist angles of A ′ and 28A ″ can be adjusted.

A laminated body of each of the optically anisotropic layers 28A to 28A '''and the polarizing plate 30 (hereinafter referred to as laminated bodies 1 to 4, respectively)
About elliptic ellipsometry ("KOBUURA-21D
H ", manufactured by Oji Scientific Instruments), and a wavelength of 480 n
The relationship between the largest difference between the polarization azimuth angles of m, 550 nm, and 630 nm and the twist angle was examined. Twist angles and wavelengths 480 nm, 550 nm and 630 n
FIG. 4 shows the relationship between m and the polarization azimuth difference. From the results shown in FIG. 4, the optically anisotropic layer 28 having a twisted structure is obtained.
A, 28A ′, and laminates 1 to 3 using 28A ″
Has a wavelength of 4 as compared with the laminate 4 using the optically anisotropic layer 28A '''having no twist structure having a twist angle of 0 °.
It was demonstrated that the difference between the polarization azimuth angles of 80 nm, 550 nm, and 630 nm was reduced.

The retardation (Re) of the produced circularly polarizing plates 1 and 4 was analyzed by wavelength dispersion analysis (“KOBUURA”).
-31PR ", manufactured by Oji Scientific Instruments). FIG. 5 shows the analysis result. Further, each of the circularly polarizing plates 1 and 4 was attached to a total reflection mirror, and the reflection characteristics were examined. FIG. 6 shows the results. From the results shown in FIG. 5, the wavelength dispersion of the circularly polarizing plate 1 including the optically anisotropic layer 28A having the twisted structure is as follows.
It was proved that the wavelength dispersion of retardation (Re) was reduced as compared with the circularly polarizing plate 4 having the optically anisotropic layer 28 '''having no twist structure. Further, from the results shown in FIG. 6, the wavelength dispersion of the circularly polarizing plate 1 provided with the optically anisotropic layer 28A having the twisted structure shows that the optically anisotropic layer 28 '''having no twisted structure is provided. It was demonstrated that the wavelength dependence of the reflectance was reduced as compared with the circularly polarizing plate 4.

Example 1 FIG. 1 provided with the circularly polarizing plate 1
A reflective liquid crystal display device having the structure shown in FIG. Liquid crystal layer 2
Numeral 0 denotes a TN-type liquid crystal layer, and when no voltage is applied, the alignment r ₂ of the liquid crystal molecules located at the interface of the alignment film 18 of the liquid crystal molecules and the alignment r _{1 at} the interface of the alignment film 22 are 4.
It was oriented to form 5 °. Incidentally, the polarization axis p of r ₂ and the polarizing plate 30 is designed so as to be parallel. Electrode layers 16 and 2
4 was bright white when no voltage was applied, and black when a voltage exceeding the liquid crystal saturation voltage was applied. The viewing angle of the display was wide.

Example 2 The circularly polarizing plate 1 was replaced with the circularly polarizing plate 2.
A reflective liquid crystal device having the same configuration as in Example 1 was produced, except that Example was replaced with Example 1. As in the first embodiment, the electrode layers 16 and 24
A bright white display was obtained when no voltage was applied, and a black display was obtained when a voltage exceeding the liquid crystal saturation voltage was applied. The viewing angle of the display was wide.

Example 3 The circularly polarizing plate 1 was replaced with the circularly polarizing plate 3.
A reflective liquid crystal device having the same configuration as in Example 1 was produced, except that Example was replaced with Example 1. As in the first embodiment, the electrode layers 16 and 24
A bright white display was obtained when no voltage was applied, and a black display was obtained when a voltage exceeding the liquid crystal saturation voltage was applied. The viewing angle of the display was wide.

Comparative Example 1 The circularly polarizing plate 1 was replaced with the circularly polarizing plate 4.
A reflective liquid crystal device having the same configuration as in Example 1 was produced, except that Example was replaced with Example 1. Compared with Example 1, the display in the state where no voltage was applied to the electrode layers 16 and 24 was slightly dark, and the display was slightly yellowish.

[0086]

According to the present invention, it is possible to stably provide a reflection type liquid crystal display device having good display performance.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of the reflective liquid crystal display device of the present invention.

FIG. 2 is a schematic diagram showing a positional relationship of each layer of the reflective liquid crystal display device shown in FIG.

FIG. 3 shows an optically anisotropic layer A used in Examples and Comparative Examples.
5 is a graph showing an example of the relationship between the twist angle of the above and the amount of chiral agent C-2 added.

FIG. 4 shows an optically anisotropic layer A used in Examples and Comparative Examples.
6 is a graph showing an example of the relationship between the twist angle of the optical fiber and the difference between the polarization azimuth angles of the wavelengths of 480 nm, 550 nm, and 630 nm.

FIG. 5 is a graph showing an example of the wavelength dependence of the retardation (Re) of a circularly polarizing plate used in Examples and Comparative Examples.

FIG. 6 is a graph showing an example of the wavelength dependence of the reflectance of a circularly polarizing plate used in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reflection type liquid crystal display device 12 Reflector 14 Back transparent substrate 16 24 Electrode layer 18 22 Alignment film 20 Liquid crystal layer 26 Front transparent substrate 27 Liquid crystal cell 28A Optically anisotropic layer A 28B Optically anisotropic layer B 28 λ / 4 plate 30 Polarizing plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/30 349 G09F 9/30 349D (72) Inventor Mitsuyoshi Ichihashi 200 Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo F-term (reference) in Film Co., Ltd. AA17 BB12 BB16 DD14 FF02 FF03 FF05 LL03 LL07 LL08 LL17

Claims (7)

[Claims] 1. A reflection type liquid crystal display device comprising a reflector, a liquid crystal cell, and a polarizing plate laminated in this order, wherein an alignment birefringence measured at a wavelength of 550 nm, a thickness, and a thickness are arranged between the reflector and the polarizing plate. Is 1
A reflection type liquid crystal display device comprising: an optically anisotropic layer A having a thickness of 50 to 350 nm and having a twisted structure; and an optically anisotropic layer B having a retardation of 60 to 170 nm. 2. The reflection type liquid crystal display device according to claim 1, wherein the optically anisotropic layer A has a twist angle of 3 ° or more and 45 ° or less. 3. The reflection type liquid crystal display device according to claim 1, wherein the optically anisotropic layer A is composed of liquid crystal molecules. 4. The reflection type liquid crystal display device according to claim 1, wherein the optically anisotropic layer B is composed of liquid crystalline molecules. 5. The reflection type liquid crystal display device according to claim 3, wherein the liquid crystal molecules are discotic liquid crystal molecules. 6. The reflective liquid crystal display device according to claim 3, wherein the liquid crystal molecules are fixed in a state of being substantially uniformly aligned. 7. The reflection type liquid crystal display device according to claim 1, wherein the optically anisotropic layer B is a stretched polymer film.