JPH07333617A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve coloration and dependency upon visual angles by arranging a phase difference plate having an optical axis between at least one polarizing plates and a liquid crystal cell. CONSTITUTION:The liquid crystal cell 14 and the phase difference plate 13 having the optical axis in the plane direction of the element are arranged between two sheets of the polarizing plates 11 and 12. The liquid crystal cell 14 forms plural pixels and the respective pixels respectively consist of two regions (a), (b). The orientation directions of both cell substrates of the respective regions are parallel and intersect orthogonally with the orientation direction of the other region. The rubbing direction of the one region is arranged in parallel with the optical axis 13a of the phase difference plate. The retardation value of the phase difference plate is set at 255 to 295mum and the refractive index anisotropy And of the liquid crystals of the liquid crystal cell is set at 255 to 295mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display element used as a display device of an office automation equipment such as a word processor or a personal computer is generally of a polarization control type, and most of the liquid crystal display elements use nematic liquid crystal. The methods are roughly classified into two methods of birefringence mode and optical rotation mode.

In the birefringence mode, there are a structure in which the nematic liquid crystal is used in a twisted state and a structure in which the nematic liquid crystal is not twisted. In the one using the twisted nematic liquid crystal, for example, it has a molecular arrangement twisted by 90 ° or more (ST method). Since it has a steep electro-optical characteristic, a large capacity display can be easily obtained by time-division driving without a switching element (thin film transistor or diode) for each pixel.

Further, in a structure using a nematic liquid crystal having no twist, for example, a homogeneous type or a vertical alignment type ECB system can be mentioned. Since it has steep electro-optical characteristics like the ST system, switching is performed for each pixel. Large-capacity display can be easily obtained by time-division driving even without elements.

On the other hand, since the optical rotation mode element has a molecular arrangement twisted by 90 ° (called TN method) and has a high response speed (tens of milliseconds) and a high contrast ratio, a clock, a calculator, and a switching element. It is possible to realize a liquid crystal display element (for example, a TFT-LCD) having a large display capacity and a high contrast and a high display performance by providing the above for each pixel. In recent years, this TFT-LCD performs gradation display, but when observed obliquely, phenomena such as display inversion, blackout, and white spots occur. This phenomenon is because the liquid crystal molecules in one pixel change azimuthally and uniformly, and as a means for solving such a problem, the liquid crystal molecule array of one pixel has a tilt direction of 180 degrees. ° Various proposals have been made that two kinds of molecular arrangements are reversed.

The electro-optical characteristics of these various liquid crystal display elements have wavelength dependence. This is because the various liquid crystal display elements are polarization control type liquid crystal display elements using a polarizing plate. The transmittance of a polarization control type liquid crystal display device using these polarizing plates can be expressed by the following formula.

Tr to f (Δnd / λ) (0) Tr: transmittance of liquid crystal display element f (): function Δnd: refractive index anisotropy Δn of liquid crystal composition and liquid crystal layer thickness d Λ: Wavelength of incident light As is apparent from the expression (0), the transmittance of the polarization control type liquid crystal display element varies depending on the wavelength of the incident light. For this reason,
These polarization control type liquid crystal display elements have wavelength dependence in the transmittance except when Δnd is 0 (for example, in the case of the vertical alignment type ECB method, in which no voltage is applied), coloration occurs. It was a problem.

[0008]

As described above, the conventional liquid crystal display device has a problem that the electro-optical characteristics thereof have wavelength dependence and the display is colored.

An object of the present invention is to obtain a liquid crystal display device capable of improving the coloring phenomenon and further improving the viewing angle dependence of the coloring.

[0010]

According to the present invention, a positive electrode sandwiched between two substrates having electrodes forming a plurality of pixels and an alignment film formed on the electrodes and having been subjected to an alignment treatment. A liquid crystal display element comprising a liquid crystal display cell including a liquid crystal layer made of a nematic liquid crystal exhibiting dielectric anisotropy, and two polarizing plates arranged with the liquid crystal cell interposed therebetween, wherein at least one of the polarized light is Between the plate and the liquid crystal cell, the retardation value is 255 to 2 so as to have an optical axis.
A retardation plate having a wavelength of 95 nm is arranged so as to have an optical axis in the plane direction of the liquid crystal display element, and the liquid crystal cell has a direction of horizontal alignment treatment with rubbing in one pixel or a slight tilt for obtaining an equivalent effect. The two directions are substantially orthogonal to each other, one direction of the alignment process is parallel to the optical axis of the retardation plate, and the two directions of the two horizontal alignment processes of the upper and lower substrates facing each other are mutually parallel. 0 ° or 1
The liquid crystal of the liquid crystal layer has an angle of 80 ° and has a structure in which the alignment of the liquid crystal molecules is not twisted by the alignment treatment, and the refractive index anisotropy Δn of the liquid crystal layer and the liquid crystal layer thickness d
The value Δnd multiplied by 0.255 μm to 0.295 μm
To obtain a liquid crystal display element.

Further, in the above, a nematic liquid crystal exhibiting a negative dielectric anisotropy is used for the liquid crystal layer, and two vertical alignment processing directions having rubbing or slight tilt to obtain the same effect are formed in one pixel. A display element is obtained.

Further, a liquid crystal display device in which the retardation value of the retardation plate is set to 255 nm to 295 nm is obtained.

Further, a liquid crystal cell comprising a lower substrate having a reflective electrode forming a plurality of pixels, an upper substrate having a transparent electrode, and a nematic liquid crystal layer having a negative dielectric anisotropy sandwiched between these substrates. And a single polarizing plate provided on the upper substrate side, a retardation plate having a retardation value of 110 nm to 138 nm is provided between the liquid crystal cell and the polarizing plate. Provided,
The liquid crystal cell has two directions of vertical alignment processing having a slight tilt to obtain the same effect as rubbing in one pixel, and the two vertical alignment processing directions are orthogonal to each other, and one vertical alignment processing is performed. Is parallel to the optical axis of the retardation plate, the vertical alignment treatment directions of the upper and lower substrates facing each other form an angle of 0 ° or 180 ° with each other, and the liquid crystal of the liquid crystal layer is aligned with the alignment treatment. The liquid crystal has a structure in which the liquid crystal molecular arrangement has no twist, and the value Δnd is obtained by multiplying the liquid crystal layer thickness d by the refractive index anisotropy Δn of the liquid crystal layer.
Is 0.110 μm or more, to obtain a liquid crystal display element.

Further, a liquid crystal display device in which the retardation plate is composed of a liquid crystal layer is obtained.

Further, it is a film-like optical anisotropic element, the refractive index (nx, ny) in the element plane direction is equal, and the refractive index (nz) in the element normal direction is different from the refractive index in the element plane direction (nz ≠ nx = ny) An optical anisotropic element having an optical axis in the element normal direction is inserted between a liquid crystal cell and a polarizing plate to obtain a liquid crystal display element.

[0016]

The present invention is a liquid crystal display device having a birefringence effect,
The principle of this birefringence mode display is that a liquid crystal cell for controlling the retardation value is sandwiched between a pair of polarizing plates, and light on the optical paths of both polarizing plates is transmitted or blocked depending on the retardation value. The present invention is configured such that a combination of a retardation plate having a fixed retardation value and a liquid crystal cell capable of controlling Δnd corresponding to the retardation value is sandwiched by a pair of polarizing plates, and each pixel of a display image is Each pixel of the liquid crystal cell for obtaining is composed of two adjacent regions (a) and (a) having different characteristics to be a divided pixel region type. Based on the retardation value of the retardation plate, the retardation value of the divided pixel region is set to have mutually positive and negative retardation values of almost the same value as that of the retardation plate, by voltage application control to the pixel electrode, Allow each value to be selected between 0 and a given retardation value.

For example, the retardation value of the retardation plate is 27
If it is set to 5 nm, the Δnd value of one pixel area (a) viewed from the retardation plate when no voltage is applied is −275 nm, and the Δnd value of the area (b) is
The nd value is 275 nm. That is, the total retardation value including the retardation plate on the optical path of the region (a) is 0, and the total retardation value including the retardation plate on the optical path of the region (a) is 550 nm. When a voltage is applied, both regions (a) and (b) are 0, and the total additive retardation value on the optical path is 275 nm in both regions.

The transmittance Tr1 when a birefringent layer having no optical rotatory power is sandwiched between two orthogonal polarizing plates on the optical path is expressed by the following equation.

Tr1 = T0.sin ² (2θ) .sin ²
(Rπ / λ) (1) T0: Transmittance of the polarizing plate θ: Angle between the polarizing plate absorption axis and the azimuth where retardation occurs R: Retardation value (corresponding to Δnd) λ: Incident light wavelength The transmittance Tr2 when sandwiched between two polarizing plates arranged in parallel is expressed by the following equation.

Tr2 = 1-Tr1 ……………………………………
………………………… (2) From these formulas (1) and (2), the transmittances Tr1 and Tr2 with respect to the retardation value can be calculated for blue, green and red light in the visible light region.
Calculations for wavelengths λ = 440, 550 and 620 nm are as shown in FIGS.

FIG. 10 shows the transmittance Tr1 when sandwiched between two orthogonal polarizing plates, and FIG. 11 shows the transmittance Tr2 when sandwiched between two polarizing plates arranged in parallel. As is clear from both figures, the transmittance changes depending on the light wavelength, and the transmittance 1 (100%) in FIG. 10 and the transmittance 0 (0
%, The shielding rate) is 215 nm at λ440 and 27 at λ550 at each wavelength even in the region where the value is close to 0.
There is a variation of 310 nm at 5 nm and λ620.

When the total retardation value is 275 nm in the voltage applied state in both the above-mentioned regions (a) and (b), FIG.
From 0, the transmittance of blue light of wavelength λ440 is about 85%, the transmittance of green light of wavelength λ550 is 100%, and the transmittance of red light of wavelength λ620 is about 97%. On the other hand, in the relationship of FIG. 11, it becomes the shielding rate as it is.

That is, although the optical wavelength dependence of the retardation value causes a coloring phenomenon, in the present invention, the characteristics of the retardation plate and the liquid crystal cell regions (a) and (b) act complementarily. , Which eliminates the coloring phenomenon, will be described below.

Representative constitutions I, II, III, IV, V of the present invention
And VI are shown in FIGS. The configurations of all the figures show the configuration of one pixel of the liquid crystal cell. (Configuration I, I
I), (Structures III and IV), and (Structures V and VI) are grouped together, but the three types of display elements in different groups have the same principle even if the structures are different, Each of them consists of light control as shown in FIG.

That is, in FIG. 7, the retardation plate 13 and the liquid crystal cell 14 are arranged between the upper and lower polarizing plates 11 and 12 whose absorption axes are arranged in the crossed Nicols state, and the liquid crystal cell is sandwiched between both polarizing plates. Make up 10. In the figure, the liquid crystal cell 14
Indicates only one pixel, and this pixel is composed of two divided areas of area (A) and area (A). Upper and lower polarization plates 11, 12
The absorption axes 11a and 12a of the display element 10 are the x-axis in the horizontal direction (or horizontal direction) of the display surface of the display element 10, the y-axis in the vertical direction (or the vertical direction), and the z-axis is the display surface normal. And are inclined 45 ° counterclockwise and 45 ° clockwise, respectively, and are arranged in a crossed Nicol relationship orthogonal to each other. The plane alignment direction of the region (a) of the liquid crystal cell 14 by the rubbing treatment is parallel to the y-axis as indicated by the arrow 14a, and the region (a)
The plane alignment direction by the rubbing process is parallel to the x-axis as shown by the arrow 14b, and the alignment directions 14a and 14b are formed so as to be orthogonal to each other. The retardation plate 13 has a maximum refractive index in the direction 13a parallel to the x-axis (optical axis), and has a refractive index anisotropy having the same refractive index in the x-axis and z-axis directions. Since the direction of the maximum refractive index is obtained by stretching a polyethylene material or the like in the production of the retardation plate, it is also referred to as a stretching axis.

With this arrangement, the rubbing orientation direction 14a in the region (a) and the optical axis 13a of the retardation plate are orthogonal to each other, and the rubbing orientation direction 14b in the region (a) and the optical axis 13 of the retardation plate 13a.
a is parallel, and the absorption axes 11a and 12a of the polarizing plates are
The angle arrangement is 45 ° with respect to.

In the drawing, optical paths La and Lb penetrating the area (a) and the area (a) are assumed, and the incident light is the lower polarizing plate 1.
It is assumed that the transmission type display element is one that enters from the second side and that exits from the upper polarizing plate 11 through the liquid crystal cell 14 and the retardation plate 13.

The light incident on the lower polarizing plate 12 is polarized and becomes a linearly polarized light L12 rotated 45 ° counterclockwise from the x-axis. When this light L12 passes through the area (a) of the liquid crystal cell 14, it becomes a straight light L14a rotated 90 ° clockwise, and further, in the phase difference plate 13, it rotates 90 ° counterclockwise to L13a.
Since it is parallel to the absorption axis 11a of the upper polarizing plate 11, the light on this optical path La is absorbed and blocked by the upper polarizing plate 11.

On the other hand, the linear light L12 incident on the area (a) of the liquid crystal cell 14 is rotated 90 ° counterclockwise by the area (a) and becomes the linearly polarized light L14b. Further, the phase difference plate 13 is rotated counterclockwise by 90 ° to become L13b and becomes parallel to the absorption axis 11a of the upper polarizing plate 11, so that the light on this optical path Lb is absorbed and blocked by the upper polarizing plate 11.

In this state, if the alignment function is removed from the regions (a) and (a) by controlling the voltage of the liquid crystal cell 14, the linearly polarized light L12 on the optical paths La and Lb will be the phase difference plate 13.
Since it rotates 90 ° counterclockwise only by,
Since the light becomes linearly polarized light that is orthogonal to the first absorption axis 11a, the light on both optical paths passes through the upper polarizing plate.

The configuration of the light control system of FIG.
, II, III, IV, V and VI, which will be described with reference to FIGS. The same reference numerals in each figure indicate similar parts.

FIG. 1 illustrates (Structure I). The arrangement state of liquid crystal molecules of a liquid crystal cell is shown on the left side, with the element cross section (ii) as the center, the arrangement of each part and the relationship (i) of each axis with respect to polarization. The relationship (iii) between and the optical axis of the retardation plate is shown on the right side.

The liquid crystal cell 14 is an upper substrate 20 made of glass.
And a lower substrate 21. The upper substrate 20 has IT on one surface
The upper pixel electrode 22 of O is formed, and the region that divides each pixel on the electrode surface is divided into a region (a) and a region (a), and the alignment film 23a and the alignment film 23b are adjacent to each other. It is formed.

IT is formed on the surface of the lower substrate 21 facing the upper substrate.
The lower pixel electrode 24 of O is formed, and the area (A) and the area (A) are formed.
Alignment films 25a and 25b are formed on the portions. The alignment film is subjected to a rubbing treatment, and a liquid crystal layer 26 of nematic liquid crystal exhibiting a positive dielectric anisotropy is filled in a gap between the alignment films of the substrate to form a liquid crystal cell 14. Alignment films 23a, 2 in the region (a)
The rubbing direction of 5a is parallel to the y-axis and 180 ° to each other.
The directions A1 and A2 are opposite to each other, and the rubbing directions of the alignment films 23b and 25b in the region (a) are directions B1 and B2 parallel to the x axis and 180 ° opposite to each other. By this alignment treatment, as shown in (ii) and (iii), the liquid crystal molecules 26
a and 26b are homogeneous arrays having a slight pretilt angle α0, and the molecular arrays in both regions are orthogonal without twist.

The retardation plate and the nematic liquid crystal have a refractive index anisotropy, and their optical characteristics can be generally expressed by a three-dimensional refractive index ellipsoid in the x-, y-, and z-axis directions. In FIG. (Iii), the thickness of the retardation film 13 is t, the layer thickness of the liquid crystal layer 26 is d,
Further, (A) indicates the refractive index anisotropy of the region (A), (A) indicates the refractive index anisotropy of the region (A), (C) indicates the refractive index anisotropy of the retardation plate 13, and Represents the arrangement relationship of. Here, nx, ny, and nz are the refractive indices of each axis.

(Structure II) shown in FIG. 2 has the same structure except that the arrangement of liquid crystal molecules in (Structure I) is a homogeneous arrangement, but is changed to a splay arrangement. In order to form a splay array, the upper and lower alignment films 33a and 35a in the region (a) are aligned in the same rubbing direction A parallel to the y-axis as shown in FIG.
1, A1 and the upper and lower alignment films 33b and 35b in the region (a)
Are oriented in the same rubbing directions B1 and B1 parallel to the x-axis. As a result, as shown in (iii), the liquid crystal molecule 2
6a and 26b are spray arrangements. The relationship of the index ellipsoid is the same as that of (Structure I).

The (Structure III) shown in FIG. 3 is obtained by adding vertical alignment treatment to the alignment films 43a and 43b in the region (a) and the alignment films 45a and 45b in the region (a) in the (Structure I). A nematic liquid crystal exhibiting a negative dielectric anisotropy is used for the liquid crystal layer 36. In this configuration, when no voltage is applied, the liquid crystal molecules are aligned slightly with respect to the alignment film from the substrate surface normal, and this tilted state is a uniform alignment 47 in the liquid crystal layer thickness direction. When a voltage is applied to the electrodes, the liquid crystal molecules are arranged almost parallel to the substrate surface.

(Structure IV) shown in FIG. 4 corresponds to (Structure I) of FIG.
The vertical alignment processing is added to the alignment films 53a and 55a in the region (a) and the alignment films 53b and 55b in the region (a) in I), and a nematic liquid crystal having a negative dielectric anisotropy is used for the liquid crystal layer 36. It was what I had. With this configuration, when no voltage is applied, the liquid crystal molecules are arranged slightly inclined with respect to the alignment film from the normal to the substrate surface, and this inclined state becomes a bent arrangement 57 having a curve in the liquid crystal layer thickness direction. When a voltage is applied to the electrodes, the liquid crystal molecules are arranged almost parallel to the substrate surface.

The (configuration V) of FIG. 5 and the configuration (VI) of FIG. 6 are those in which the light reflection by the reflector formed by the lower pixel electrode 40 of aluminum is included once in the optical path,
The liquid crystal layer for display, the retardation plate and the polarizing plate are incident light and reflected light twice, that is, the light travels back and forth through each layer, and
It becomes the optical path shown in.

The (configuration V) of FIG. 5 corresponds to the (configuration III) of FIG. 3, and the (configuration VI) of FIG. 6 corresponds to the (configuration IV) of FIG.

In each of the above configurations, (configuration I), (configuration
In II), when no voltage is applied, the total retardation values on the optical path including the retardation plate are 0 and 550 nm, and when a voltage capable of arranging liquid crystal molecules almost vertically is applied. Total retardation value is 275n
m is the configuration, and (configuration III), (configuration I
V), (Structure V) and (Structure VI), conversely, a nematic liquid crystal composition exhibiting negative dielectric anisotropy is sandwiched between vertically aligned substrates having a slight tilt as a liquid crystal layer for display. Therefore, the total retardation value becomes 275 nm in the state where no voltage is applied, and the total retardation is obtained when the liquid crystal molecules are tilted to some extent or when a voltage that can be partially horizontally aligned is applied. The values are 0 and 550 nm.

As shown in FIG. 7, the retardation value of the liquid crystal layer is effectively 275 n when observed from the normal direction of the device.
When m is reached (state A. state A is subjected to horizontal alignment treatment (configuration I), and the element having the structure of (configuration II) is subjected to vertical alignment treatment when no voltage is applied (configuration III), (configuration IV), 7 is generated when a voltage is applied), the liquid crystal layer (when no voltage is applied), the optical axis of the retardation plate and the liquid crystal molecule alignment direction are as shown in FIG.
The area (A) is orthogonal and the area (A) in FIG. 7 is parallel. When observed from the element normal direction, the total retardation values of the liquid crystal layer and the retardation film (effective retardation value is 275 nm) in the region of FIG. 7A are 0 because the respective optical axes are orthogonal to each other. Becomes On the contrary, in the region of FIG. 7A, since the respective optical axes are parallel to each other, the total retardation value of the liquid crystal layer and the retardation plate is 550 nm, which is the sum of the respective retardation values.

Further, when the retardation value of the liquid crystal layer is effectively 0 (state B. horizontal alignment treatment (configuration I
), (Structure II), the element was subjected to vertical alignment treatment when voltage was applied (Structure III), (Structure IV), (Structure V),
When no voltage is applied to the element having the structure of (Structure VI), the total retardation values of the liquid crystal layer and the retardation film are summed in both regions (a) and (b) of FIG. 7 when observed from the element normal direction. The retardation value is 275 nm because it is only the retardation value of the retardation plate.

That is, in the region of FIG. 7A, the total retardation value of the liquid crystal layer and the retardation film can be changed from 0 to 275 nm (275 nm to 0) by controlling the electric field. In the region of, the total retardation value of the liquid crystal layer and the retardation plate by electric field control,
550nm to 275nm (275nm to 550n
It can be changed to m).

Therefore, it is considered that the changes in the total retardation values of the liquid crystal layer and the retardation film with respect to the applied voltage in the regions of FIGS. 7A and 7B are graphed as shown in FIGS. 8 and 9. Here, FIG. 8 shows an element having a structure of (configuration I) and (configuration II) subjected to horizontal alignment processing, and FIG. 9 shows a configuration of vertical alignment processing (configuration III), (configuration IV), and (configuration V).
FIG. 6 is a theoretical diagram in the case of an element having a structure of (Configuration VI).

Further, as shown in FIGS. 1 to 7, the angle formed by the absorption axis of the lower polarizing plate on the incident light side and the azimuth in which the total retardation of the liquid crystal layer and the retardation plate occurs in the liquid crystal display element of the present invention is In any case, it becomes 45 °.

Here, referring to FIGS. 10 and 11, λ = 5
Consider the transmittance for 50 nm light. The curves of FIG. 8 and the curves of FIGS. 10 and 11 are combined in order to know the change in the transmittance with respect to the applied voltage in various configurations of the liquid crystal display device of the present invention in each of the regions (A) and (B) shown in FIG. did. The results are shown in FIGS. In any of the figures, the regions (a) and (a) shown in FIG. 7 result in the same curve.

As described above, in the liquid crystal display device of the present invention, one pixel is composed of two alignment regions, and in these two alignment regions, the change in retardation value with respect to the applied voltage is different (see FIG. 8). Therefore, the change of the transmittance with respect to the applied voltage shows the same way of change in any of the regions if only the light of λ = 550 nm is considered. This means that the total retardation of the sum of the liquid crystal layer and the retardation plate is exactly 1.0 times this λ = 550 nm,
This is because it is 0.5 times and 0 times, and the value of (Rπ / λ) in the expressions (1) and (2) indicating the above-mentioned transmittance is 0, π / 2, π and the minimum of the sine function. This is because the condition is that the maximum value is 0.

Next, other blue light, red light, that is, λ = 4
Let's consider what happens in the case of 40 nm and 620 nm. 14, 15, 16 and 17 are shown in FIGS.
Similarly, the curve of FIG. 8 and the curves of FIGS.
FIG. 7 is a composite of m and 620 nm, and shows changes in transmittance with respect to an applied voltage for regions (a) and (a) shown in FIG. 7, respectively. 14 and 1
5 is the result of λ = 440 nm, and FIGS.
The result is 0 nm. Further, in the figure, the curve indicated by the solid line is the curve of the synthesis result at λ = 550 nm shown in FIGS.

As can be seen from the figure, λ = 440 nm, 62
The curve showing the change in the transmittance with respect to the applied voltage in the regions (A) and (A) at 0 nm is different from the curve showing the change in the transmittance with respect to the applied voltage at λ = 550 nm. That is, the shape is shifted upward or shifted downward with respect to λ = 550 nm. However, in any of the figures, if the area (a) is shifted upwards, the area (a) is shifted downwards, and if the area (a) is shifted upwards,
(A) is shifted downward.

As described above, the liquid crystal display element of the present invention has a structure in which two alignment regions, that is, regions (a) and (a) shown in FIG. 7 are provided in one pixel. Therefore,
The transmittance of each pixel is a combination of the transmittances of the areas (A) and (A) shown in FIG.
Therefore, the change in the transmittance with respect to the applied voltage at each incident light wavelength of each liquid crystal display element shown in FIGS. 12 to 17 is the average of the curves of the regions (a) and (a) in each of the diagrams. . Here, in the case of λ = 550 nm shown in FIGS. 12 and 13, the curves of the regions (A) and (A) overlap each other, and naturally the averages also overlap. Further, λ = 440 nm and 620 shown in FIGS.
As described above, the curve of nm has the regions (A) and (B).
Thus, the curves deviate from the curve of λ = 550 nm in opposite directions. Therefore, λ = 440n shown in FIGS.
The averages of the curves (a) and (a) at m and 620 nm substantially match the curves of λ = 550 nm shown in FIGS. As a result, when the transmittance of the liquid crystal display device of the present invention is considered with one pixel as one unit, the change in the transmittance with respect to the applied voltage is almost the same curve (how to change) regardless of the wavelength of the incident light. Will be.

As described above, the liquid crystal display device of the present invention exhibits electro-optical characteristics (transmittance-applied voltage curve) with extremely little wavelength dependence.

Next, the features and functions of the configurations of the three groups of the liquid crystal display element of the present invention will be described in order.

The structures shown in (Structure I) and (Structure II) are both transmissive liquid crystal display devices, and as described above, the alignment process for one pixel is divided into two. The liquid crystal molecular alignment of the driving liquid crystal display cell is a horizontal alignment having a slight tilt in both the regions (a) and (a) and has no twist. In the configuration I, the tilt direction of the slight tilt (that is, the rubbing direction)
Is 180 ° opposite on the upper and lower substrates (such a molecular arrangement is generally called a homogeneous arrangement), and in (Structure II), the tilt directions of the slight tilts are the same on the upper and lower substrates (this molecular arrangement is Generally called a spray arrangement). The structures shown in (Structure I) and (Structure II) have almost the same birefringence when no voltage is applied when observed from the direction normal to the device, but observed obliquely. In this case, the dependence of birefringence on the viewing direction is different between (Structure I) and (Structure II). In the structure of (Structure I), since the molecular alignment of the liquid crystal layer is a so-called homogeneous alignment, the tilt direction of the liquid crystal molecules is uniformly oriented in a fixed direction. For this reason, the birefringence is significantly dependent on the viewing direction. On the other hand, in (Structure II), since the molecular alignment of the liquid crystal layer is a so-called splay alignment, the tilt direction of the liquid crystal molecules is 180 degrees in the upper half of the liquid crystal layer.
° Reversed direction. Therefore, when observed obliquely, the birefringence value becomes almost the same value even if a certain observation direction is compared with the observation direction 180 ° opposite. Therefore, in this configuration, the birefringence is less dependent on the viewing direction because the orientation is small. However, in (Structure II), since the molecular arrangement is a splay arrangement, it is possible to take two tilt directions when a voltage is applied, so that the liquid crystal molecule tilt angles of the substrate surfaces are different between the upper and lower substrates. If the control is performed such that the tilt direction when the voltage is applied is only one direction by using a method or the like, an alignment defect such as tilt reverse occurs when the voltage is applied. In this way, although there are merits and demerits in comparing (Structure I) and (Structure II), these structures have the following features.

The alignment treatment of the liquid crystal layer is horizontal alignment having a slight tilt, and a simple and inexpensive manufacturing method such as a rubbing method can be performed.

When a voltage is applied, that is, when the liquid crystal molecules are tilted, the tilt directions are two directions within one pixel (orthogonal to each other), and the effect of compensating for the viewing angle dependency is produced and the viewing angle dependency is obtained. It is possible to realize a liquid crystal display device with less power consumption.

As described above, since the wavelength dependence of transmitted light is self-corrected, the viewing angle dependence of color is small despite the birefringence effect type.

What is shown in (Structure III) and (Structure IV) is
The liquid crystal molecules of the liquid crystal display cell in (Structure I) and (Structure II) are almost vertically aligned, and the liquid crystal composition used is a nematic liquid crystal composition exhibiting negative dielectric anisotropy. In other words, the effective retardation is set to 0 when no voltage is applied, and by controlling the voltage to be approximately 275 nm, the sum of the retardation of the retardation plate and the retardation of the liquid crystal display cell is controlled. , 275 nm when no voltage is applied, and 0 and 550 nm when voltage is applied.

Compared with the configurations shown in (Structure I) and (Structure II), this structure has exactly the opposite electro-optical characteristics, and has the same retardation as the retardation plate when no voltage is applied. Sum of retardation of liquid crystal display cell is 275n
Since it is m, this state is low voltage (that is, 0V)
It is a feature that can be obtained in. In the liquid crystal display device of the present invention, the sum of the retardation of the retardation plate and the retardation of the liquid crystal display cell is 275 nm and 0 and 550 nm.
And the state is controlled by an electric field.
) And (Structure II), it is necessary to align the liquid crystal molecules substantially vertically to obtain the retardation (275 nm) of one of them. This requires a sufficient voltage, in practice an effective voltage of 7-8V.
On the other hand, in the structures shown in (Structure III) and (Structure IV), the sum of the retardation of the retardation plate and the retardation of the liquid crystal display cell is 275 nm, which is obtained by no voltage application, and the 0 and 550 nm states are also obtained. , Δn of liquid crystal layer
If d is increased, the liquid crystal molecules will be slightly (horizontally).
Since it can be obtained by letting it lie down, it can be obtained by a low applied voltage (2 to 3 V). Further, if Δnd of the liquid crystal layer is made large, the retardation of the liquid crystal layer can be changed by a slight change in the molecular arrangement, so that the electro-optical characteristics become steep, and even a simple electrode structure can be driven by multiplex driving. Therefore, an inexpensive liquid crystal display device can be realized.

Further, the difference between (Structure III) and (Structure IV) is whether the liquid crystal molecule arrangement is a so-called bend arrangement or a uniform arrangement when no voltage is applied. In the former bend arrangement, the arrangement direction (tilt direction) of the liquid crystal molecules is exactly 180 ° between the upper half and the lower half of the liquid crystal layer thickness direction.
The arrangement is reversed (this is the arrangement of (Structure IV)), and in the latter uniform arrangement, the liquid crystal molecules are arranged in a uniform direction (tilt direction) from bottom to top in the liquid crystal layer thickness direction. There is something. Similar to the difference between (Structure I) and (Structure II), such a difference between (Structure III) and (Structure IV) leads to a difference in viewing angle dependence of the liquid crystal display element.
That is, the viewing angle dependency is better in (configuration IV) than in (configuration III). Also, the configuration of (Configuration IV) is (Configuration
Unlike the configuration of II), even if the tilt angles of the upper and lower substrates are the same, the liquid crystal molecules can lie down in two directions when a voltage is applied, so that an alignment defect such as reverse may occur when a voltage is applied. In addition, there is no need to differentiate the alignment process between the upper and lower substrates.

The structures shown in (Structure V) and (Structure VI) show a structure in which the operation of the present invention is applied to a reflection type LCD using only one polarizing plate. On the optical path,
Each of the liquid crystal layer, the phase difference plate layer, and the polarizing plate layer is used for the incident light and reflected light.
Since it passes twice, the retardation value of each layer is
III), half the value of (Structure IV).
The reflective structure shown in (Structure V) and (Structure VI) is similar to the transmissive structure shown in (Structure III) and (Structure IV).
Since the liquid crystal molecule alignment is vertically aligned when no voltage is applied, it has the same characteristics as those shown in (Structure III) and (Structure IV), and the incident light and the reflected light are observed even when observed obliquely from the optical path. Then, even if the liquid crystal molecule has the configuration (configuration V),
Even with the configuration of VI), since the polarities are just opposite, it is possible to obtain a display with very little viewing angle dependency.

In any of the constitutions of the liquid crystal display device of the present invention, the retardation value is 0 when observed from the direction of the device direction, and the retardation value is other than 0 (> 0 or <0 when observed obliquely). ), It is possible to obtain even more excellent properties by applying a treatment that reduces the viewing angle dependence, such as the display when viewed from the front when viewing from an angle, by adding an optical film that Becomes

For example, with respect to the structures of (Structure III), (Structure IV), (Structure V) and (Structure VI), the refractive index anisotropy is negative and the refractive index in the plane direction is An optical film that is equivalent (that is, a film exhibiting a refractive index anisotropy in which nx = ny> nz (nz is a refractive index in the normal direction)) may be added.

In the explanation of the operation, the retardation value of the retardation plate is 275 nm. Other values can be selected for this value, and light control of almost the entire visible light range is possible by selecting 270 nm or its vicinity from FIGS. 10 and 11 and practically a range of 255 nm to 295 nm. is there. It goes without saying that these values are halved in the reflective elements of (Structure V) and (Structure VI).

[0065]

EXAMPLES Examples of the liquid crystal display device of the present invention will be described in detail below.

Example 1 This example relates to (Structure I).

In FIG. 1, the size of one pixel p is 100.
μm × 300 μm, pixel pitch is 110 μm × 3
The TFT substrate 24 having a size of 30 μm and the number of pixels of (640 × 3) × 480 and a size of about 10 inches and the TF.
A common substrate 20 with an ITO solid electrode having an RGB color filter corresponding to the pixels of the T substrate is prepared, and polyimide (ALS made by Nippon Synthetic Rubber Co., Ltd.) is used as alignment films 23a, 23b, 25a, 25b on both the substrates. -3046
(Average pretilt angle is about 4 °)
After baking at 30 ° C for 30 minutes, the orientation treatment direction of each pixel is (configuration I
) Both the substrates are rubbed in the direction of the area (a), and a resist is further applied to this, and an exposure process is performed by resist development so that the area (a) is covered, After the development step, the both substrates are rubbed so that the (A) region of (Structure I) is exposed and the orientation processing direction is the direction of the (A) region of (Structure I). After that, the resist was completely removed to obtain an alignment-treated substrate for the liquid crystal cell 14 of this example. These substrates 2
0 and 21 were used as a substrate interstitial agent so that the liquid crystal layer thickness would be 4.4 μm. In addition, a nematic liquid crystal material (ZLI-1695 manufactured by Merck Japan Co., Ltd. (Δn = 0.062) showing positive dielectric anisotropy as liquid crystal between these substrates.
5)) was injected by a vacuum injection method to form a liquid crystal layer 26, and the injection port at this time was sealed with an ultraviolet curable resin to obtain a liquid crystal cell 14 used in this example.

The liquid crystal cell 14 has a structure (I) as a retardation plate 13 as NRF54 manufactured by Nitto Denko Corporation.
0-NRF540-NRF280 3-layer laminated retardation film (R = 2 at average wavelength λ = 550 nm)
75 nm, R / λ = λ / 2) to the liquid crystal cell 14 of the present embodiment.
And the absorption axes 11a and 12a are orthogonal to each other between the polarizing plates 11 and 12 so that the absorption axis of the polarizing plate and the retardation direction (optical axis direction) 13a of the retardation plate make an angle of 45 °. The retardation plate 13 and the liquid crystal cell 14 were inserted to obtain a liquid crystal display element 10I.

The electro-optical characteristics of the liquid crystal display device thus obtained were measured with light of λ = 440 nm, 550 nm and 620 nm, and the results are shown in FIG. As shown in the figure, it was found that electro-optical characteristics having extremely little wavelength dependence can be obtained. Furthermore, when the isocontrast characteristics of the obtained liquid crystal display device were measured at an applied voltage of 0-8V, a contrast ratio of 150: 1 on the front side and a contrast ratio of 10: 1 or more up to a viewing angle of 30 ° were obtained, and a very wide viewing angle dependency was obtained. I understood it. Furthermore, when the display color of the liquid crystal display device of this example was observed, it was found that an extremely excellent tint with almost no coloring was obtained even if the front surface was changed in viewing angle.

(Example 2) (Structure II) In FIG. 2, the same substrate as in Example 1 was used, and only the alignment films 33a and 33b on the common substrate 11 side were manufactured by Nippon Synthetic Rubber Co., Ltd. AL-1051 (average). Pretilt angle is about 1
°), the liquid crystal display element 10 of the present example is prepared by using the same materials, conditions and manufacturing method as in Example 1 except that rubbing is performed so that the orientation treatment direction of each pixel in Example 1 is (Structure II).
I got II.

As in Example 1, the electro-optical characteristics of the obtained liquid crystal display element were determined to be λ = 440 nm, 550 nm and 620 nm.
When measured with the light, the almost same result as in Example 1 was obtained. Further, when the isocontrast characteristics of the obtained liquid crystal display device were measured at an applied voltage of 0 to 8 V, the contrast ratio was 150: 1 on the front side, and the contrast ratio was 15: 1 or more up to a viewing angle of 30 °, which is extremely higher than that of Example 1. It was found that a wide viewing angle dependence was obtained. Furthermore, as in Example 1,
When the display color of the liquid crystal display element of this example was observed, it was found that, as in the case of Example 1, of course, an extremely excellent tint with almost no coloring was obtained even when the viewing angle was changed.

(Example 3) (Structure I) A liquid crystal cell having the structure shown in FIG. 19 was used as a phase difference plate instead of the phase difference plate 13 in Example 1 to obtain a liquid crystal display element of this example. The liquid crystal cell having the structure shown in FIG. 19A used here has AL-made by Nippon Synthetic Rubber Co., Ltd. as alignment films 62 and 63 on glass substrates 60 and 61 having a thickness of 0.3 mm.
3046 was rubbed in the direction shown in FIG. 19A, and Micropearl (particle size 6.5 μm) manufactured by Sekisui Fine Chemical Co., Ltd. was used as a substrate gap agent so that the liquid crystal layer 64 had a layer thickness of 6.5 μm. The spray molecules are sprayed on the one substrate 61, the both substrates 60, 61 are superposed, and a liquid crystal composition is formed between the substrates as a liquid crystal composition even if an unexpected electric field (charging due to static electricity) or a magnetic field occurs. ZLI-2806 manufactured by Merck Japan Co., Ltd. is used as a nematic liquid crystal material exhibiting negative dielectric anisotropy so that the array 65 does not change.
(Δn = 0.042) was injected by a vacuum injection method, and the injection port at this time was sealed with an ultraviolet curable resin.

The liquid crystal display element of the present example thus obtained was evaluated in the same manner as in Example 1. As a result, excellent characteristics similar to those in Example 1 were obtained, and the liquid crystal display element of the present invention had a retardation plate. As a result, it was confirmed that a similar effect can be obtained by using a liquid crystal cell having the same function as the retardation plate of the polymer film instead of the retardation plate.

Example 4 (Structure III) In FIG. 3, the same substrates 20 and 21 as in Example 1 were used,
Both of the substrates are immersed in an ODS-E (vertical alignment treatment agent) solution manufactured by Chisso Co., Ltd., and then baked at 150 ° C. for 30 minutes to form a vertical alignment film 43a on both substrate surfaces.
43b, 45a and 45b were obtained. After that, the both substrates are rubbed A1 and A2 so that the orientation processing direction of each pixel is the direction of the area of FIG. Due to
An exposure process is performed to cover the area (a), a development step is performed, and the alignment treatment direction (structure III) is set so that the area (FIG. 3A) in (structure III) is exposed. Rubbing the both substrates so that they are oriented in the area b),
After that, the resist was completely removed to obtain an alignment-treated substrate for a liquid crystal display device of this example. Micropearls (particle size 6.5 μm) manufactured by Sekisui Fine Chemical Co., Ltd. as a substrate interstitial agent were sprayed on the common substrate 20 side so that the liquid crystal layer 36 had a layer thickness of 6.5 μm.
Both of the above-mentioned substrates were superposed on each other, and the nematic liquid crystal material having negative dielectric anisotropy, ZLI-2806 (Δn = 0.042) used in Example 3 was injected between these substrates by a vacuum injection method. Then, the injection port at this time was sealed with an ultraviolet curable resin to obtain a liquid crystal cell of this example.

As in Example 1, the liquid crystal cell has a structure of (Structure III) as N retarder of Nitto Denko Corporation as a retardation plate.
A three-layer laminated retardation film of RF540 / NRF540 / NRF280 (R = 275 nm at the average wavelength λ = 550 nm, R / λ = λ / 2) was attached to the liquid crystal display cell in the present example, and the polarizing plate 11 was formed by intersecting them orthogonally. , 12 between the absorption axes 11a and 12a of the polarizing plate and the retardation direction (optical axis direction) 13a of the retardation plate.
The retardation plate 13 and the liquid crystal cell 14 were inserted so that the angle of 45 ° was 45 ° to obtain a liquid crystal display element 10III of this example.

FIG. 20 shows the results of measuring the electro-optical characteristics of the liquid crystal display device thus obtained with light of λ = 440 nm, 550 nm and 620 nm. As shown in the figure, it was found that electro-optical characteristics having extremely little wavelength dependence can be obtained. Further, when the isocontrast characteristics of the obtained liquid crystal display device were measured at an applied voltage of 0-6V, a contrast ratio of 200: 1 on the front side and a contrast ratio of 10: 1 or more up to a viewing angle of 30 ° were obtained, which was a very wide viewing angle dependency. I understood it. Further, when the display color of the liquid crystal display device of the present invention was observed, it was found that, of course, even if the viewing angle was changed, an extremely excellent tint was obtained with almost no coloring.

(Fifth Embodiment) (Structure IV) In FIG. 4, the same substrate as in the fourth embodiment is used, and the alignment films 53a, 53b, 55a, 55b of the respective pixels in the fourth embodiment are used.
A liquid crystal display element 10IV of this example was obtained by using the same materials, conditions, and manufacturing method as in Example 4, except that rubbing was performed so that the alignment treatment direction was (Structure IV).

The electro-optical characteristics of the obtained liquid crystal display device were set to λ = 440 nm, 550 nm and 620 nm as in Example 4.
When measured with the light of, the almost same result as in Example 4 was obtained. Further, when the isocontrast characteristics of the obtained liquid crystal display element were measured at an applied voltage of 0-5V, the contrast ratio was 200: 1 on the front side, and the contrast ratio was 15: 1 or more up to a viewing angle of 30 °, which is extremely higher than that of Example 4. It was found that a wide viewing angle dependence was obtained. Furthermore, as in Example 4,
When the display color of the liquid crystal display element of this example was observed, it was found that, as in the case of Example 4, the front side could have an extremely excellent tint with almost no coloring even when the viewing angle was changed.

(Example 6) (Structure III) In FIG. 3, the electrodes 22 are formed in a stripe shape as the substrate 20, the width thereof is 100 μm, and the pattern pitch is 11
0 μm, the number of electrodes is (640 × 3), and an ITO patterning substrate for signal electrodes, which is equipped with color filters of different colors (RGB) for each electrode pattern, and
The electrode width is 300 μm and the pattern pitch is 330 μm.
m, and the ITO electrode patterned substrate 21 for scanning electrodes having 480 electrodes was subjected to the same alignment treatment as in Example 4, and these substrates were used as a substrate gap agent so that the liquid crystal layer thickness was 6.5 μm. Micropearl (particle size 6.5 μm) manufactured by Sekisui Fine Chemical Co., Ltd. was sprayed on the lower substrate 21 side, both the substrates were superposed, and the negative dielectric anisotropic used in Example 3 between these substrates. A nematic liquid crystal material exhibiting properties, ZLI-4850 (Δn = 0.208), is injected by a vacuum injection method, and the injection port at this time is sealed with an ultraviolet curable resin to form a structure (III). A liquid crystal cell used in the present invention was obtained.

The liquid crystal display cell thus obtained has
The liquid crystal display element of this example was obtained by combining the retardation plate 13 and the polarizing plates 11 and 12 in the same manner as in Example 4 so as to obtain the structure I).

Electro-optical characteristics were measured in the same manner as in Examples 1 and 4, and the results shown in FIG. 21 were obtained. As is apparent from the figure, it is needless to say that the wavelength dependence is extremely small as in Examples 1 and 4, and the characteristics are extremely steep, and the liquid crystal display element of this example is a characteristic suitable for multiplex driving. It was confirmed.

Further, as in Examples 1 and 4, the isocontrast characteristics of the liquid crystal display device were measured by multiplex driving (driving execution voltage 3-4V) of 1/480 duty driving. , Viewing angle 30
It was found that a very wide viewing angle dependency with a contrast ratio of 5: 1 or more up to ° was obtained. Further, when the display color of the liquid crystal display device of the present invention was observed, it was found that, of course, even if the viewing angle was changed, an extremely excellent tint was obtained with almost no coloring.

(Embodiment 7) (Structure V) An opaque (black) glass substrate 70 having a concave and convex reflective pixel electrode 40 and an acrylic resin insulating layer 71 as shown in FIG. 22 is used as a substrate, and a TFT is provided for each pixel. TFT substrate with switching element 72 (the size of one pixel is 30
0 μm × 300 μm with a pixel pitch of 304 μm ×
304 μm and the number of pixels is 640 × 480, about 9
(Inch size) 21 and solid ITO as shown in FIG.
Using the common substrate 20 on which the electrodes 22 are formed, the same alignment treatment as in Embodiment 4 is performed in the alignment treatment directions A1, A2, B1 of the respective pixels.
, B2 as shown in (Structure V), and used as a substrate gap agent for these substrates so that the liquid crystal layer thickness is 4.5 μm. Micropearl (particle size 4.5 μm) manufactured by Sekisui Fine Chemical Co., Ltd. On the common substrate 20 side,
Both of the substrates were superposed, and a nematic liquid crystal material having negative dielectric anisotropy, ZLI-2806 (Δn = 0.042) used in Examples 3, 4, and 5 was vacuum-injected between the substrates. To form a liquid crystal layer 36, and the injection port at this time was sealed with an ultraviolet curable resin to obtain a liquid crystal cell 14 used in this example. Δnd of the liquid crystal layer 36 is 137 μm.

As in Example 1, the liquid crystal cell had a structure (V) as a retardation plate manufactured by Nitto Denko Corp.
A three-layer laminated retardation film of RF270 / NRF270 / NRF140 (R = 137 nm at the average wavelength λ = 550 nm, R / λ = λ / 4) was attached to the outside of the common substrate 20 of the liquid crystal display cell in the present embodiment, and these were adhered to them. The polarizing plate 11 is laminated on the retardation plate so that the absorption axis 11a of the polarizing plate and the retardation direction (optical axis direction) 13a of the retardation plate form an angle of 45 °, and the liquid crystal display device of the present embodiment. I got 11V.

The electro-optical characteristic (reflected light intensity with respect to the applied voltage) of the liquid crystal display element thus obtained was λ = 440n.
FIG. 23 shows the results of measurement with light of m, 550 nm, and 620 nm. As shown in the figure, it was found that electro-optical characteristics having extremely little wavelength dependence can be obtained. Furthermore, the isocontrast characteristics of the obtained liquid crystal display element were measured by applying no applied voltage.
When measured at -4V, the contrast ratio is 1 at the front.
It was found that a very wide viewing angle dependency was obtained with a contrast ratio of 3: 1 or more up to 0: 1 and a viewing angle of 30 °. Further, the maximum reflectance when a voltage was applied was measured, and it was found that the reflectance was extremely high at 44.8%. Further, when the display color of the liquid crystal display device of the present invention was observed, it was found that, of course, an extremely excellent tinge with almost no coloring was obtained even when the viewing angle was changed.

(Embodiment 8) (Structure V) In FIG. 5, as the signal electrode substrate 20, the ITO for signal electrodes in which the width of the electrodes 22 is 300 μm, the pattern pitch is 330 μm, and the number of electrodes is 640 × 3. The patterning substrate 20 and the reflective electrode 40 having an uneven electrode width of 300 μm, a pattern pitch of 330 μm, and the number of electrodes of 480 on the acrylic resin insulating layer 81 having an uneven surface as shown in FIG. After using the scanning electrode patterning substrate 21 using the opaque (black) glass substrate 80 having the above, the same alignment treatment as in Example 4 is performed so that the alignment treatment direction of each pixel is as shown in (Structure V). One of the substrates was Micropearl (particle size 6.5 μm) manufactured by Sekisui Fine Chemical Co., Ltd. as a substrate gap agent so that the liquid crystal layer thickness of these substrates was 6.5 μm. Sprinkle on the side,
Both of the substrates were superposed, and a nematic liquid crystal material having negative dielectric anisotropy, ZLI-4850 (Δn = 0.208) used in Examples 3, 4 and 5 was vacuum-injected between the substrates. Was injected to form a liquid crystal layer 36, and the injection port at this time was sealed with an ultraviolet curable resin to obtain a liquid crystal cell used in this example.

A retardation plate 13 and a polarizing plate 11 were attached to this liquid crystal cell in the same manner as in Example 7 so that the liquid crystal cell had the configuration (V) to obtain a liquid crystal display element of this example.

The electro-optical characteristic (reflected light intensity with respect to the applied voltage) of the liquid crystal display element thus obtained was λ = 440n.
FIG. 25 shows the results of measurement with light of m, 550 nm, and 620 nm. As in Example 6, the electro-optical characteristics of this example were extremely steep, and it was confirmed that the liquid crystal display element of this example was suitable for multiplex driving.

Further, the same contrast characteristics of the liquid crystal display element were measured by a 1/480 duty driving multiplex driving (driving effective voltage 2-3V) as in Example 6, and a contrast ratio of 6: 1 at the front and a viewing angle were obtained. It was found that an extremely wide viewing angle dependency with a contrast ratio of 3: 1 or more up to 30 ° was obtained. Further, when the display color of the liquid crystal display device of the present invention was observed, it was found that, of course, even if the viewing angle was changed, an extremely excellent tint was obtained with almost no coloring.

(Embodiment 9) (Structure VI) In FIG. 6, rubbing directions A 1 and B in embodiment 7 are shown.
A liquid crystal display element 10VI of the present example was obtained by using the same materials, conditions and manufacturing method as in Example 7, except that (Structure VI) was the same as in Example 1 except that Example 1 was changed from Example 4. .

Similarly to Example 7, the electro-optical characteristics of the obtained liquid crystal display element were measured with light of λ = 440 nm, 550 nm and 620 nm. When measured at 0 to 4 V, it was found that a contrast ratio of 10: 1 on the front side and a contrast ratio of 4: 1 or more up to a viewing angle of 30 ° were obtained, which is extremely wide viewing angle dependency as compared with Example 7 or more. In addition, when the maximum reflectance when a voltage was applied was measured, it was found that the reflectance was extremely high as in Example 7. Further, when the display color of the liquid crystal display device of the present invention was observed, it was found that, of course, an extremely excellent tinge with almost no coloring was obtained even when the viewing angle was changed.

(Embodiment 10) In FIG. 1, (Structure I)
In the liquid crystal display device in Example 1, two retardation plates, which are the film-shaped optical anisotropic elements used in Examples 7 to 9, are arranged orthogonally between the retardation plate 13 and the polarizing plate 11. The optical axis was inserted so as to form an angle of 45 ° with the optical axis 13a of the retardation plate.

This anisotropic element has an element plane direction (x axis, y
The optical films have the same refractive index nx and ny (nx = ny) in the axial direction, and the refractive index nz in the element normal line (z axis) direction is different from the planar direction refractive index (nnx ≠ nz, nz ≠ ny).
In this example, an optical film having a negative refractive index anisotropy (nx = ny> nz) (retardation R = -100 nm) was used. The refractive indices nx, ny and nz are nx and ny = 1, respectively.
55616, nz = 1.55601, film thickness 80.0 μm. A film (trade name: VAC-100, Sumitomo Chemical Co., Ltd.) or the like can be used.

When the electro-optical characteristics were measured in the same manner as in Example 1, the same results as in Example 1 were obtained, and when the isocontrast characteristics were measured at an applied voltage of 0-8V, the contrast ratio of 130: 1 on the front side was obtained. It was found that a contrast ratio of 30: 1 or more up to a viewing angle of 30 ° and an extremely wide viewing angle dependency were obtained as compared with Example 1 or more. Further, when the display color of the liquid crystal display device of this example was observed, it was found that, as in the case of Example 1, the front side could have an extremely excellent tint with almost no coloring even when the viewing angle was changed. . In the above embodiments, the retardation value R of the retardation plate and the variation range of Δnd of the liquid crystal cell are set to be the same, but the same effect can be practically obtained even if the values are slightly different.

[0095]

According to the present invention, it is possible to obtain electro-optical characteristics with extremely little wavelength dependence and to obtain a very wide viewing angle dependence. Furthermore, of course, even if the viewing angle is changed on the front side, an extremely excellent tint with almost no coloring is obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of configuration I of the present invention.

FIG. 2 is a diagram illustrating an example of configuration II of the present invention.

FIG. 3 is a diagram illustrating an embodiment of configuration III of the present invention.

FIG. 4 is a diagram illustrating an example of configuration IV of the present invention.

FIG. 5 is a diagram for explaining an embodiment of configuration V of the present invention.

FIG. 6 is a diagram illustrating an example of configuration VI of the present invention.

FIG. 7 is a schematic diagram illustrating an optical configuration and action of the liquid crystal display element of the present invention.

FIG. 8 is an applied voltage-retardation value curve diagram for explaining the operation of the present invention.

FIG. 9 is an applied voltage-retardation value curve diagram for explaining the operation of the present invention.

FIG. 10 is a curve diagram showing the relationship between transmittance and retardation value (at the time of crossed Nicols).

FIG. 11 is a curve diagram showing the relationship between transmittance and retardation value (when parallel).

FIG. 12 is a curve diagram showing a transmittance-applied voltage characteristic (when crossed Nicols λ = 550 nm) for explaining the operation of the present invention.

FIG. 13 is a curve diagram showing the transmittance-applied voltage characteristics (when parallel λ = 550 nm) for explaining the operation of the present invention.

FIG. 14 is a curve diagram showing transmittance-applied voltage characteristics (when crossed Nicols λ = 440 nm) for explaining the operation of the present invention.

FIG. 15 is a curve diagram showing the transmittance-applied voltage characteristics (when parallel λ = 440 nm) for explaining the operation of the present invention.

FIG. 16 is a curve diagram showing transmittance-applied voltage characteristics (when crossed Nicols λ = 620 nm) for explaining the operation of the present invention.

FIG. 17 is a curve diagram showing the transmittance-applied voltage characteristics (when parallel λ = 620 nm) for explaining the operation of the present invention.

FIG. 18 shows the transmittance of an embodiment of the liquid crystal display device of the present invention-
The curve diagram which shows the applied voltage characteristic measurement result.

FIG. 19 shows a retardation plate of one embodiment of the liquid crystal display device of the present invention, (a) showing a rubbing direction, (b).
Is a schematic sectional view showing the structure.

FIG. 20 shows the transmittance of an example of the liquid crystal display device of the present invention.
The curve diagram which shows the applied voltage characteristic measurement result.

FIG. 21 shows the transmittance of an embodiment of the liquid crystal display device of the present invention-
The curve diagram which shows the applied voltage characteristic measurement result.

FIG. 22 shows a T used in an example of the liquid crystal display element of the present invention.
Sectional drawing of an FT board.

FIG. 23 shows the transmittance of an embodiment of the liquid crystal display element of the present invention-
The curve diagram which shows the applied voltage characteristic measurement result.

FIG. 24 is a sectional view of a substrate used in an example of the liquid crystal display element of the present invention.

FIG. 25 shows the transmittance of an example of the liquid crystal display element of the present invention-
The curve diagram which shows the applied voltage characteristic measurement result.

[Explanation of symbols]

10I, 10II, 10III, 10IV, 10V, 10VI ...
Liquid crystal display device 11, 12 ... Polarizing plate 13 ... Retardation plate 14 ... Liquid crystal cell 20 ... Upper substrate 21 ... Lower substrate 22 ... Upper electrodes 23a, 23b ... Alignment film 24 ... Lower electrodes 25a, 25b ... Alignment film 26 ... Liquid crystal layer A1, A2, B1, B2 ... Orientation direction 11a, 12a ... Absorption axis 13a ... Optical axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Oyama 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Co., Ltd. Toshiba Corporation Yokohama Works (72) Inventor Hitoshi Hato 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Company Toshiba Yokohama Office

Claims (6)

[Claims] 1. A nematic liquid crystal having a positive dielectric anisotropy sandwiched between two substrates having electrodes for forming a plurality of pixels and an alignment film formed on the electrodes and having been subjected to an alignment treatment. A liquid crystal display element comprising a liquid crystal display cell comprising a liquid crystal layer comprising the liquid crystal layer and two retardation plates arranged with the liquid crystal cell sandwiched between the at least one polarizing plate and the liquid crystal cell. Has a retardation value of 255 to 295n so as to have an optical axis.
A polarizing plate of m is arranged so as to have an optical axis in the plane direction of the liquid crystal display device, and the liquid crystal cell has two directions of horizontal alignment processing with rubbing or a slight tilt to obtain the same effect in one pixel. And the two directions are substantially orthogonal to each other, and the direction of one orientation process is parallel to the optical axis of the retardation plate,
The directions of the two horizontal alignment treatments of the upper and lower substrates facing each other form an angle of 0 ° or 180 ° with each other,
The liquid crystal of the liquid crystal layer is a liquid crystal in which the alignment of the liquid crystal molecules is not twisted by the alignment treatment, and the value Δnd obtained by multiplying the refractive index anisotropy Δn of the liquid crystal layer and the liquid crystal layer thickness d is 0.2.
A liquid crystal display device having a thickness of 55 μm to 0.295 μm. 2. A liquid crystal layer comprising a nematic liquid crystal sandwiched between the two substrates having electrodes forming a plurality of pixels and an alignment film formed on the electrodes and having been subjected to an alignment treatment. In a liquid crystal display element comprising a liquid crystal display cell formed by the above and two polarizing plates arranged with the liquid crystal cell interposed therebetween, retardation is performed so that an optical axis is provided between the at least one polarizing plate and the liquid crystal cell. Value is 255-295n
The retardation plate of m is arranged so as to have the optical axis in the plane direction of the liquid crystal display element, and the liquid crystal cell has a direction of vertical alignment treatment having a slight tilt for rubbing or obtaining the same effect in one pixel. And the two directions are substantially orthogonal to each other, and the direction of one alignment treatment is parallel to the optical axis of the retardation plate,
The directions of the two horizontal alignment treatments of the upper and lower substrates facing each other form an angle of 0 ° or 180 ° with each other,
The liquid crystal of the liquid crystal layer is a nematic liquid crystal exhibiting a negative dielectric anisotropy and is a liquid crystal having a structure in which the alignment of the liquid crystal molecules does not have a twist by the alignment treatment.
A value Δnd obtained by multiplying n by the liquid crystal layer thickness d is 0.22 μm to 0.295 μm. 3. The retardation value of the retardation plate is 230 nm.
3. The liquid crystal display element according to claim 1, wherein the liquid crystal display element has a thickness of 270 nm to 270 nm. 4. A liquid crystal cell comprising a lower substrate having a reflective electrode forming a plurality of pixels, an upper substrate having a transparent electrode, and a liquid crystal layer of nematic liquid crystal exhibiting negative dielectric anisotropy sandwiched between these substrates. And a retardation plate having a retardation value of 110 nm to 138 nm between the liquid crystal cell and the polarizing plate, in a liquid crystal display device comprising: a polarizing plate provided on the upper substrate side. The liquid crystal cell has two vertical alignment processing directions having a slight tilt to obtain the same effect as rubbing in one pixel, and the two vertical alignment processing directions are orthogonal to each other. The direction of the alignment treatment is parallel to the optical axis of the retardation plate, the vertical alignment treatment directions of the upper and lower substrates facing each other form an angle of 0 ° or 180 °, and the liquid crystal of the liquid crystal layer is At serial alignment treatment is a liquid crystal which is a structure having no liquid crystal molecular arrangement twist, the value Δnd multiplied by the refractive index anisotropy Δn and liquid crystal layer thickness d of said liquid crystal layer
Is 0.110 μm or more, a liquid crystal display device. 5. The phase difference plate comprises a liquid crystal layer.
Alternatively, the liquid crystal display element according to item 3. 6. A film-shaped optical anisotropic element, wherein the refractive index (nx, ny) in the element plane direction is equal and the refractive index (nz) in the element normal direction is different from the refractive index in the element plane direction (nz 5. The liquid crystal display element according to claim 1, 2 or 4, wherein an optical anisotropic element having an optical axis in the direction normal to the element is inserted between the liquid crystal cell and the polarizing plate.