JP3405337B2 - Liquid crystal display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display element.
About the child. 2. Description of the Related Art Conventional reflection type TN mode and reflection type STN
In mode, no backlight is required and power consumption is low.
Mobile personal computers and word processors.
It has been widely used in products such as FIG. 27 shows a conventional reflection type TN mode and a reflection type TN mode.
FIG. 1 is a cross-sectional view of a liquid crystal display device using a type STN mode.
A conventional liquid crystal display element includes a liquid crystal cell 1 and both sides thereof.
Polarizing plates 2 and 3 arranged on the side and outside the polarizing plate 3
And a reflecting plate 4 that can be used. [0004] However, the conventional
Liquid crystal display using reflective TN mode or reflective STN mode
The display element has a problem that the display is dark. Especially reflection
In the case of the type STN mode, coloring of display is also an issue.
Was. Further, the display unique to the reflection mode has a double display.
There was also a problem that it looked like. FIG. 28 shows a conventional reflection type STN liquid crystal display element.
The spectral characteristics of the element when the electric field is off and when it is on are shown. 4 in the figure
1 is the spectral characteristic when the electric field is off, and 42 is the spectral characteristic when the electric field is on.
is there. However, the cell condition is such that the twist angle is 255 degrees, Δn ×
d is 0.85 μm, the distance between the polarization axis direction and the rubbing direction is
The angle is 45 degrees. STN mode is thus off
The color of the display is remarkable, yellowish green when turned on and blue when turned on.
The reflectance was as low as 65%, and the visibility was poor. The present invention solves such a problem.
The goal is to use a new reflective LCD mode
By introducing a bright, less colored,
To provide a liquid crystal display device in which the display does not look double
It is in. [0008] A liquid crystal display device of the present invention.
Has a twisted liquid crystal layer sandwiched between a pair of substrates.
And polarizing means disposed on one of the substrates, and the other
The substrate having irregularities formed on the liquid crystal layer side of the substrate
Electric field off state in a liquid crystal display device comprising
Luminous reflectance in the field is higher than luminous reflectance in the electric field on state
And the liquid crystal layer is in the state where the electric field is off.
Light incident on the liquid crystal layer via optical means is transmitted through the liquid crystal layer.
Is converted to an elliptically polarized state by
Set to be converted and reach the reflection surface of the reflection means
It is characterized by having been done. In the above-mentioned liquid crystal cell, the twist of liquid crystal
The strike angle is 0 degree or more and 70 degrees or less, and the Δn × d value is 0.
2 μm or more and 0.7 μm or less, and the angle θ is 35 degrees or more
It is characterized by being at most 115 degrees. More preferred
Is a twist angle of 30 degrees or more and 70 degrees or less, Δn ×
d value is 0.25 μm or more and 0.64 μm or less, and the angle is
is desirably 58 degrees or more and 111 degrees or less. In the above-mentioned liquid crystal cell, the twist of liquid crystal
The strike angle is 170 degrees or more and 270 degrees or less, and Δn × d value
Is 0.4 μm or more and 1.0 μm or less.
You. [0011] More preferably, the twist angle is 175 degrees or less.
Upper 210 degrees or less, Δn × d value is 0.51 μm or more
0.75 μm or less, and the angle θ is 42 degrees or more and 71 degrees or less
Bottom or twist angle is more than 250 degrees and 265
Degrees or less, Δn × d value is 055 μm or more and 0.96 μm
m and the angle θ is not less than −2 degrees and not more than 30 degrees.
Is desirable. Further, among the two substrates of the liquid crystal cell,
A step of 0.1 μm is formed on the liquid crystal side surface of at least one of the substrates.
It is characterized by having irregularities of 2 μm or less. Further, the reflection plate is provided on the liquid crystal cell substrate.
It is characterized by being provided on the liquid crystal side surface. The reason for the above numerical limitation is as follows.
This will be described in detail in the following operation section. According to the liquid crystal display device of the present invention, the brightness is particularly improved.
Was emphasized, and one polarizing plate, which was conventionally used in two sheets, was changed to one sheet. side
By using one light plate, at least the effect of the polarizing plate can be obtained.
It becomes brighter by the percentage, and this alone has a brightness of about 12%
The top is expected. In order to obtain more ideal brightness, polarization
Linearly polarized light entering the liquid crystal cell through the plate causes the liquid crystal layer to
Passes through the polarizer with the same linear polarization again
There is a need. However, such changes in polarization are limited.
It only occurs under the conditions. We examined this condition diligently.
As a result, the light that enters the liquid crystal cell and reaches the reflective surface is linearly polarized.
What is necessary is to adjust the conditions of the liquid crystal cell so that
found. This will be described in detail with reference to FIG. FIG.
(A) is a figure which shows the orientation of a liquid crystal molecule, 2 is polarization.
Plate, 11 is an upper substrate, 16 is a liquid crystal molecule, and 4 is a reflector.
You. On the other hand, FIG. 4B is a diagram showing a change in the polarization state.
You. Light incident from the left is converted into linearly polarized light by the polarizing plate 2.
Become. Next, no phase difference is caused by the birefringence of the liquid crystal molecules.
However, it generally changes to elliptically polarized light. This light is a reflector
When it reaches, it is linearly polarized as shown
In the return path, where light is reflected and travels to the left,
Following the same polarization change, it returns to the original linear polarization,
It can pass through the polarizer without loss. This phenomenon can be explained as follows. FIG.
The reflection type liquid crystal mode of the present invention shown in FIG.
It is optically equivalent to the transmission type liquid crystal mode of (b). this
FIG. 5B shows a symmetrical shape with respect to the surface 17 on which the reflection plate exists.
In this example, liquid crystal molecules and a polarizing plate are arranged. By the way, two sheets having the same retardation
Are superimposed so that the optical extraordinary axes are orthogonal to each other.
The phenomenon that the phase difference of the phase difference plate is compensated is
Well known from Applying this principle to liquid crystal display devices
The reason is that d proposed in Japanese Patent Publication No. 64-519, etc.
New Twisted Nematic mode (hereafter NTN mode)
C). NTN mode is retardation
Are equal and the twist directions are opposite.
This is a mode in which files are stacked. FIG. 5C shows the liquid crystal component.
FIG. 9 is a view showing a cell arrangement, which is
A pair of liquid crystal molecules in a positional relationship are orthogonal to each other,
Compensation is provided by exactly the above principle. In the reflection type liquid crystal display device,
In order for linearly polarized light to be emitted in the same linearly polarized state,
(B) The liquid crystal molecule arrangement shown in FIG.
Need to be done. The present inventor has proposed that the center plane 17 of the liquid crystal layer
This condition is satisfied when the light is linearly polarized.
I found it to be done. This is a pair of liquid crystal cells
Even if the polarizing plate is rotated by 90 degrees, the optical characteristics change.
You can easily confirm from the facts that do not exist. Now, the light enters the liquid crystal cell and reaches the reflection surface.
There are many cell conditions under which light becomes almost linearly polarized light.
However, all the conditions can be used as a liquid crystal display
Not enough contrast ratio when voltage is applied
Are further limited. For example, when the twist angle is 60 degrees, the liquid crystal
Light incident on the cell and reaching the reflecting surface becomes almost linearly polarized light
The range of the cell condition is the area indicated by hatching in FIG.
You. FIG. 12 shows a twist angle of 60 degrees.
At the time of the cell condition to obtain a good contrast ratio
It is a figure showing a range. However, the horizontal axis here is the retardance
△ n × d, and the vertical axis is based on the polarization axis direction of the polarizing plate.
This is the angle θ between the plate and the orientation of the liquid crystal. 51, 5
2, 53 are respectively 1:20, 1:10, 1: 5 or more
Is a region in which the contrast ratio can be obtained. Where the angle θ
Gives exactly the same result even if an integer multiple of 90 degrees is added.
So, in these figures, 0 degree and 90 degree are continuous
You can think that there is. Now, from FIG. 12, in the case of a 60 degree twist
Has a contrast of Δn × d = 0.46 μm and θ = 4 degrees
To maximize the contrast ratio and obtain a sufficient contrast ratio.
It can be seen that the file condition is limited to its vicinity. Thus, the light enters the liquid crystal cell and reaches the reflecting surface.
The condition that the light reached is almost linearly polarized is a good table.
Not enough to get an indication, but
I can say. Similarly, each twist of 0 to 270 degrees
Cell conditions that maximize the contrast ratio at
Investigations are summarized in FIG. FIG. 7 shows a liquid crystal cell obtained under the conditions shown in FIG.
This is a summary of the optical characteristics of the device. The horizontal axis is the twist of the liquid crystal
The vertical axis represents the contrast ratio C.I.
R. , Off-state luminous reflectance Yoff, and degree of coloring
The match is $ E. Yoff is the brightness of the reflector with a polarizing plate
100%, but due to surface reflections,
But it is only about 85%. $ E is CIE1
Using a * and b * in 976L * A * B * color system
And a * ^Two + B * ^Two Is the value defined by the square root of
The smaller the value, the smaller the color of the display.
are doing. From FIG. 7, it is sufficient for a high-quality display.
To obtain a contrast ratio of 1:10 or more,
The strike angle is 0 to 70 degrees, or 170
It is necessary to be within the range of not less than 265 degrees. What
If the twist angle is between 265 degrees and 270 degrees,
The trust ratio drops to about 1: 6, but
Has a steep electro-optical characteristic suitable for large-capacity displays
Therefore, it becomes practical enough. Further, in particular, the twist angle is 30 degrees or more and 70 degrees.
Less than or equal to, 175 degrees or more and 210 degrees or less, 2
If the angle is 50 degrees or more and 265 degrees or less, the display is colored
, The better display is possible. It should be noted that the claims and the problems described above are solved.
In the section of the means for determining, limit the twist angle range
, The Δn × d value and the angle θ were also limited.
FIG. 6 summarizes cell conditions for obtaining high contrast, and FIG.
Cell condition showing good contrast ratio at ist angle
9 to 23 showing the range of the above are used as the grounds. What
9 to 23, reference numerals 51, 52, and 53 designate
Contrast ratios of 1:20, 1:10, 1: 5, etc.
Contrast curve, 1: 5 or less for normal display
In addition, a contrast ratio of 1:10 or more is required for high image quality display.
It was determined that it was important. On the other hand, if irregularities are provided on the inner surface of the liquid crystal cell,
The coloring of the display can be further reduced. this is
The effect is that the coloring is averaged by the change in the liquid crystal layer thickness.
You. In particular, when a metal film having irregularities is provided on the inner surface of the cell,
In this case, this doubles as an omnidirectional reflector,
Can solve the problem of However, concave
If the convex step is less than 0.1 μm,
There is almost no reduction effect, and the metal film does not show omnidirectionality
It will be a mirror surface. Also, when the step exceeds 2 μm
In addition, the color of the LCD is rather large,
The decrease of the last ratio is remarkable. This is shown in FIG.
This occurs when a general liquid crystal of n = 0.08 is used.
ば ら つ き n × d value variation of 0.16 μm
It is easy to understand. Hereinafter, the present invention will be described in detail with reference to Examples.
Show details. (Embodiment 1) FIG. 1 shows a liquid according to the present invention.
It is sectional drawing of a crystal display element. In the figure, 1 is a liquid crystal cell, 2 is
The polarizing plate 4 is a reflection plate. 11 is the upper substrate, 12
Is a lower substrate, 13 is a transparent electrode, and 15 is a liquid crystal. liquid crystal
Is ZLI-4472 manufactured by Merck (８７n = 0.087)
Using 1), twist the liquid crystal cell with a cell gap of 5.3 μm.
A strike orientation was performed. Retardation △ nxd is 0.46
μm. FIG. 3 shows the relationship between the axes of the liquid crystal display device of the present invention.
It is the figure which looked at the person from the observation direction. 21 is the polarization of the polarizing plate 2
Optical axis direction, 22 is the rubbing direction of the upper substrate, 23 is the lower substrate
Rubbing direction. Also, 31 becomes 22 from 21
Angle θ (the twist direction of the liquid crystal is a positive value);
Is shown. Here, angle θ is 4 degrees, twist
The corner was set at 60 degrees to the left. FIG. 24 shows a liquid crystal produced under the above conditions.
FIG. 3 is a diagram illustrating spectral characteristics of a display element. In the figure, 41 is an electric field
Reference numeral 42 denotes spectral characteristics when the electric field is turned on. off
Luminous reflectance Yoff is as high as 81%.
The color is almost white. In addition, the luminous reflectance when on is 2.4%
Low, the maximum possible contrast ratio C.I. R. Is
1:34. The liquid crystal display element of this embodiment has a twist angle
Although it is as small as 60 degrees, the steepness of its voltage transmittance characteristics is usually
Of the twisted nematic mode of
1/2 Duty to 1/16 Duty Multiplex
Drive is also possible. In FIG. 12, the twist angle is the same as in this embodiment.
When the angle is 60 degrees, it is possible to obtain a good display contrast.
The range of the rule conditions is shown. Note that the angle θ has a 90-degree
Exactly the same result can be obtained by adding several times. Therefore, θ =-
10 degrees is equivalent to θ = 80 degrees or θ = 170 degrees.
is there. Also, 51, 52 and 53 in the figure are
Equal contrasts with a trust ratio of 1:20, 1:10, 1: 5
It is a curve. Inside these equal contrast curves,
Can be expected to have good display. For example, △ n ×
When d = 0.60 μm and θ = 16 degrees, C.I. R. =
1:16, Yoff = 80%. Also, △ n × d =
When θ = −6 degrees at 0.34 μm, C.I. R. = 1: 1
0, Yoff = 71%. Also, Δn × d = 0.4
When θ = −6 degrees at 8 μm, C.I. R. = 1: 6, Yo
ff = 84%. Conversely, good display is not possible outside the curve.
Absent. For example, θ = −12 degrees when Δn × d = 0.28 μm
At the time of C. R. = 1: 3, Yoff = 62%
You. Also, when Δn × d = 0.72 μm and θ = 4 degrees
Is C.I. R. = 1: 2, Yoff = 76%. Ma
Also, when Δn × d = 0.40 μm and θ = 30 degrees,
C. R. = 1: 0.4, Yoff = 24%. Therefore, when the twist angle is 60 degrees, the twist angle is small.
At least Δn × d value is 0.3 μm or more and 0.7 μm or less
The angle θ must be within the range of −13 degrees to 25 degrees.
It is necessary. (Embodiment 2) The liquid crystal display device of Embodiment 2 is also
The configuration is similar to that of the first embodiment. However, the liquid crystal cell 1 of FIG.
Is ZLI-4436 manufactured by Merck (１０n = 0.110)
0) was used. The cell gap is 5.4 μm,
The gradation Δn × d is 0.59 μm. In FIG. 3, the angle 31 (θ) is 6
0 degree and the twist angle 32 were set to 200 degrees to the left. FIG. 25 shows a liquid crystal produced under the above conditions.
FIG. 3 is a diagram illustrating spectral characteristics of a display element. Luminous reflection when off
The rate Yoff is relatively high at 70%, and the display color is
Close to white. In addition, the luminous reflectance at the time of on is as low as 3.3%.
The maximum possible contrast ratio C.I. R. Is 1:21
It is. The liquid crystal display device of this embodiment is the same as the liquid crystal display device of the first embodiment.
Is steeper by the larger twist angle than the crystal display element.
Suitable for multiplex driving. FIG. 17 shows that the twist angle is the same as that of this embodiment.
Good display contrast can be obtained at 200 degrees
The range of cell conditions is shown. Contrast cars 51, 52, 53, etc.
Good display can be expected on the inside of the wing. example
For example, when Δn × d = 0.66 μm and θ = 64 degrees,
C. R. = 1: 11, Yoff = 75%. Also, when Δn × d = 0.58 μm and θ = 52
At the time, C.I. R. = 1: 8, Yoff = 77%
You. Conversely, good display is not possible outside the curve.
Absent. For example, Δn × d = 0.70 μm and θ = 46 degrees
Sometimes C.I. R. = 1: 2, Yoff = 62%.
When Δn × d = 0.5 μ and θ = 90 degrees, C.I.
R. = 1: 0.3, Yoff = 19%. Therefore, when the twist angle is 200 degrees,
At least Δn × d value is 0.48 μm or more and 0.72 μm
Below, the angle is between 48 degrees and 70 degrees
There is a need. (Embodiment 3) The liquid crystal display device of Embodiment 3 is also
The configuration is similar to that of the first embodiment. However, the liquid crystal cell 1 of FIG.
Is ZLI-4427 (@ n = 0.112) manufactured by Merck
7) was used. The cell gap is 6.6 μm,
The gradation Δn × d is 0.74 μm. here,
For the alignment film, polyimide RN-721 manufactured by Nissan Chemical Industries, Ltd.
Into a liquid crystal by rotating rubbing of rayon flocking cloth
A pretilt angle of about 10 degrees was provided. Also, in FIG.
Angle 31 (θ) is 14 degrees and twist angle 32 is 25
Set to 5 degrees. FIG. 26 shows a liquid crystal produced under the above conditions.
FIG. 3 is a diagram illustrating spectral characteristics of a display element. Luminous reflection when off
The ratio Yoff is as high as 79%, and the display color is close to white.
No. Also, the luminous reflectance at the time of on is as low as 3.2%,
Large contrast ratio C.I. R. Is 1:25
You. The liquid crystal display element of this embodiment has a twist angle
Very large at 255 degrees with very good voltage transmittance characteristics
Multiplex drive with 1/480 duty
High display contrast of 1:18
Was. FIG. 20 shows that the twist angle is the same as that of this embodiment.
At 255 degrees, good display contrast is obtained
The range of cell conditions is shown. Each of the contrast cars 51, 52, 53
Good display can be expected on the inside of the wing. example
For example, when Δn × d = 0.70 μm and θ = 5 degrees, C.I.
R. = 1: 11, Yoff = 78%. Also, △ n
× d = 0.90 μm and θ = 28 degrees, C.I. R. =
1: 9, Yoff = 71%. On the other hand, outside the curve, good display is not possible.
Absent. For example, Δn × d = 0.50 μm and θ = 55 degrees
Sometimes C.I. R. = 1: 1, Yoff = 81%. Further, θ = 30 degrees when Δn × d = 1.1 μm
At the time of C. R. = 1: 3, Yoff = 63%
You. Therefore, when the twist angle is 255 degrees,
At least Δn × d value is 0.52 μm or more and 0.98 μm
Below, the angle θ falls within the range of −4 degrees to 32 degrees.
There is a need. (Embodiment 4) FIG. 2 shows a liquid crystal display of this embodiment.
It is sectional drawing of an element. In the figure, 1 is a liquid crystal cell, 2 is a polarizing plate
It is. 11 is an upper substrate, 12 is a lower substrate, and 13 is transparent.
A bright electrode, 14 is a reflection film also serving as a pixel electrode, and 15 is a liquid crystal.
is there. The conditions of the liquid crystal cell were the same as those in Example 1,
Averaged using ZLI-4472 (Δn = 0.0871)
Δn × d is 0.46 μm, the twist angle is 60 degrees,
The angle θ was 4 degrees. The reflection film 14 is made of a rub having a surface irregularity of 0.5 μm.
Metallic aluminum thin film on the glass surface by sputtering
It is provided with a film and has reflection characteristics with little directivity.
You. In addition, as metal, nickel and nickel
Any material having a silvery white color such as chrome can be used.
Roughness can be caused by rough metal surface polishing or chemical treatment.
May be provided. When this reflective film is patterned into a comb shape or the like,
In this case, a method of directly patterning the metal thin film,
A transparent electrode is provided on a metal thin film via an insulator.
There is a method of patterning an electrode. This insulation is
Large twist angle due to the effect of reducing surface irregularities
D / p margin (d: cell gap, p: spontaneous
(H) is effective when it is narrow. As described above, the reflection plate is provided in the liquid crystal cell.
By doing so, it is unique to conventional reflective liquid crystal display elements,
Can solve the problem that the display looks double
You. In addition, minute variations in liquid crystal thickness average display colors
There is also a secondary effect of reducing coloring. What
In this case, the variation of the liquid crystal thickness of 0.5 μm is represented by △
It corresponds to the nxd value of 0.04 μm,
The fact that the influence has little effect on the contrast ratio
It is clear from FIG. (Embodiment 5) In Embodiment 1, the twist
Angle to 0 degree, Δn × d to 0.28 μm, angle θ to 44 degrees
Except having performed, it carried out similarly to Example 1. At this time, C. R. =
1:27, Yoff = 76%. The liquid crystal display element of this embodiment has a twist angle
The feature that it is easy to manufacture because it is 0 degrees
There is. FIG. 9 shows that when the twist angle is 0 degree,
Indicates the range of cell conditions that provide good display contrast.
Was. In this case, at least the Δn × d value is 0.22 μm.
The angle θ is 34 degrees or more and 55 degrees or less in a range from m to 0.32 μm.
It is indispensable to get good display in the following
It is. (Embodiment 6) In Embodiment 1, the twist
Angle 30 degrees, Δn × d 0.30 μm, angle θ 66 degrees
The procedure was the same as in Example 1 except for the above. At this time, C. R.
= 1: 32, Yoff = 78%. FIG. 10 shows a case where the twist angle is 30 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
22 μm or more and 0.3 μm or less, and the angle θ is 55 degrees or more and 7
Being less than 7 degrees is not good for obtaining a good display.
It is vital. (Embodiment 7) In Embodiment 1, the twist
Angle 45 degrees, Δn × d 0.34 μm, angle θ 76 degrees
The procedure was the same as in Example 1 except for the above. At this time, C. R.
= 1: 34, Yoff = 80%. FIG. 11 shows a case where the twist angle is 45 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
25 ° or more and 0.50µm or less, angle θ is 64 ° or more
The fact that the angle is less than 94 degrees is important for obtaining a good display.
It is essential. (Eighth Embodiment) In the first embodiment, the twist
Angle to 70 degrees, Δn × d to 0.48 μm, angle θ to 8 degrees
Except having performed, it carried out similarly to Example 1. At this time, C. R. =
1:10, Yoff = 81%. FIG. 13 shows a case where the twist angle is 70 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
36 to 0.61 μm, angle θ is -6 degrees or more
Being within 21 degrees is important for obtaining a good display.
It is essential. (Embodiment 9) In Embodiment 2, the twist
Angle is 170 degrees, Δn × d is 0.72 μm, angle θ is 46
The procedure was the same as in Example 2 except that the procedure was repeated. At this time, C.
R. = 1: 13, Yoff = 67%. FIG. 14 shows a case where the twist angle is 170 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
60μm or more and 0.82μm or less, angle θ is 37 ° or more
Being less than 55 degrees is important for obtaining a good display.
It is essential. (Embodiment 10) In Embodiment 2, the twist
Angle 175 degrees, Δn × d 0.70 μm, angle θ 4
The procedure was the same as Example 2 except that the angle was changed to 8 degrees. At this time, C.
R. = 116. Yoff = 71%. FIG. 15 shows a case where the twist angle is 175 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
58μm or more and 0.81μm or less, angle θ is 37 ° or more
Being less than 57 degrees is important for obtaining a good display.
It is essential. (Embodiment 11) In Embodiment 2, the twist
Angle 180 °, Δn × d 0.68 μm, angle θ 5
The procedure was the same as in Example 2, except that the angle was 0 degrees. At this time, C.
R. = 1: 18, Yoff = 74%. The liquid crystal display device of this embodiment has a color display.
Is smaller than the liquid crystal display element of the second embodiment in that
Excellent. FIG. 16 shows a case where the twist angle is 180 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
The angle θ is 40 degrees or more in the range of 55 μm or more and 0.79 μm or less.
Being less than 60 degrees is important for obtaining a good display.
It is essential. (Example 12) In Example 2, the twist
G is 190 degrees, Δn × d is 0.62 μm, and angle θ is 5
The procedure was the same as Example 2 except that the temperature was changed to 4 degrees. At this time, C.
R. = 1: 21, Yoff = 74%. (Embodiment 13) In Embodiment 2, the twist
G is 210 degrees, Δn × d is 0.58 μm, and angle θ is 6
The procedure was the same as in Example 2 except that the temperature was changed to 6 degrees. At this time, C.
R. = 1: 20, Yoff = 64%. FIG. 18 shows a case where the twist angle is 210 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
46μm or more and 0.71μm or less, angle θ is 54 ° or more
Being below 76 degrees is important for obtaining a good display.
It is essential. (Example 14) In Example 2, the twist
Angle 225 degrees, Δn × d 0.56 μm, angle θ 7
The procedure was the same as in Example 2 except that the temperature was changed to 6 degrees. At this time, C.
R. = 1: 20, Yoff = 54%. (Embodiment 15) In Embodiment 3, the twist
Angle is 240 degrees, Δn × d is 0.62 μm, and angle θ is −
The procedure was the same as in Example 2, except for twice. At this time, C.
R. = 1: 23, Yoff = 62%. (Embodiment 16) In Embodiment 3, the twist
Angle is 250 degrees, Δn × d is 0.70 μm, angle θ is 8
The procedure was the same as in Example 3 except that the procedure was repeated. At this time, C.
R. = 1: 27, Yoff = 74%. FIG. 19 shows a case where the twist angle is 250 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
Angle θ is -7 degrees or more in the range from 51 μm to 1.05 μm
The fact that it is within 35 degrees is important for obtaining a good display.
It is essential. (Embodiment 17) In Embodiment 3, the twist
Angle is 260 degrees, Δn × d is 0.74 μm, angle θ is 1
The procedure was the same as Example 3 except that the temperature was changed to 6 degrees. At this time, C.
R. = 1: 16, Yoff = 80%. The liquid crystal display device of this embodiment has a color display.
Is smaller than the liquid crystal display element of Example 3 in that
Excellent. FIG. 21 shows a case where the twist angle is 260 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least Δn × d value is 05
5 to 0.96 μm, the angle θ is 0 to 32
It is impossible to get good display if it is below the degree
Is missing. (Embodiment 18) In Embodiment 3, the twist
Angle 265 degrees, Δn × d 0.74 μm, angle θ 1
The procedure was the same as Example 3 except that the angle was changed to 8 degrees. At this time, C.
R. = 1:10, Yoff = 81%. The liquid crystal display element of this embodiment has a color display.
The liquid crystal display according to the third or sixteenth embodiment is
It is better than the element. FIG. 22 shows a case where the twist angle is 265 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
When the angle θ is 4 degrees or more and 3 μm or more,
If the angle is less than 0 degrees, it is difficult to obtain a good display.
It is vital. (Embodiment 19) In Embodiment 3, the twist
G is 270 degrees, Δn × d is 0.70 μm, and angle θ is 1
The procedure was the same as Example 3 except that the angle was changed to 8 degrees. At this time,
R. = 1: 6, Yoff = 80%. The liquid crystal display device of this embodiment has electro-optical characteristics
Example 3 and Example 16 in the point that the steepness of
It is superior to the liquid crystal display element of Example 17. FIG. 23 shows a case where the twist angle is 270 degrees.
Range of cell conditions to obtain good display contrast
showed that. In this case, at least the Δn × d value is equal to 0.
The angle θ is 12 degrees or more from 64 μm to 0.81 μm.
Being below 26 degrees is a key to obtaining a good display.
It is essential. (Comparative Example 1) In Example 1, the twist
Angle 75 degrees, Δn × d 0.48 μm, angle θ 10 degrees
The procedure was the same as in Example 1 except for the above. At this time, C. R.
= 1: 6, Yoff = 81%. This property is
It is the best that can be obtained with a twist angle.
The condition range in which the contrast ratio can be obtained is very narrow. This is a book
It is out of the scope of the invention and is satisfactory under such conditions.
Display cannot be performed. (Comparative Example 2) In Example 2, the twist
The angle is 165 degrees, Δn × d is 0.76 μm, and the angle θ is 46
The procedure was the same as in Example 2 except that the procedure was repeated. At this time,
R. = 1:10, Yoff = 61%. Also display
Is significantly larger than that of Example 10 or the like. this
Is outside the scope of the claims of the present invention.
It is not possible to perform a brief display. (Comparative Example 3) In Example 3, the twist
The angle is 285 degrees, Δn × d is 0.70 μm, and the angle θ is 20
The procedure was the same as in Example 3 except that the procedure was repeated. At this time, C.
R. = 1: 2, Yoff = 82%. This property is
It is the best that can be obtained with this twist angle. This is the original
Table that is outside the scope of
Cannot be shown. In the above embodiment, the twist angle
Takes discrete values in units of 5 degrees, but this is simply
This is due to experimental circumstances. Characteristic change due to twist angle
Since the conversion is continuous, the twist shown in the claims etc.
Any value is acceptable within the range of the angle. As described above, according to the present invention, a new
Bright color by introducing a new reflective LCD mode
Liquid crystal display element with little stickiness and no double view
A child can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a liquid crystal display device in Examples 1 to 3 and Examples 5 to 19 and Comparative Examples 1 to 3 of the present invention. FIG. 2 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention. FIG. 3 is a diagram showing a relationship between axes of the liquid crystal display element of the present invention. FIG. 4 shows the liquid crystal molecular orientation (a) of the liquid crystal display device of the present invention.
FIG. 4 is a diagram showing a change in polarization state (b). FIG. 5 shows the liquid crystal molecular alignment (a) of the reflection type liquid crystal display device of the present invention, the transmission type liquid crystal molecule alignment optically equivalent thereto (b), and the conventional NTN mode liquid crystal molecular alignment (C). FIG. FIG. 6 is a diagram showing a cell condition that maximizes a contrast ratio. FIG. 7 is a diagram showing three optical characteristics (contrast ratio CR, luminous reflectance Yoff when turned on, and degree of coloring ΔE) of a liquid crystal cell obtained under a cell condition where the contrast ratio is maximized. is there. FIG. 8 is a diagram showing a range of cell conditions in which when a twist angle is 60 degrees, light incident on a liquid crystal cell becomes substantially linearly polarized on a reflection surface and a high reflectance is obtained. FIG. 9 is a diagram illustrating a range of cell conditions in which a good display contrast can be obtained when the twist angle is 0 degree. FIG. 10 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 30 degrees. FIG. 11 is a diagram showing a range of cell conditions where a good display contrast can be obtained when the twist angle is 45 degrees. FIG. 12 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 60 degrees. FIG. 13 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 70 degrees. FIG. 14 is a diagram showing a range of cell conditions where a good display contrast can be obtained when the twist angle is 170 degrees. FIG. 15 is a diagram showing a range of cell conditions where a good display contrast is obtained when the twist angle is 175 degrees. FIG. 16 is a diagram showing a range of cell conditions in which good display contrast can be obtained when the twist angle is 180 degrees. FIG. 17 is a diagram showing a range of cell conditions in which good display contrast can be obtained when the twist angle is 200 degrees. FIG. 18 is a diagram showing a range of cell conditions under which a good display contrast can be obtained when the twist angle is 210 degrees. FIG. 19 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 250 degrees. FIG. 20 is a diagram showing a range of cell conditions where a good display contrast is obtained when the twist angle is 255 degrees. FIG. 21 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 260 degrees. FIG. 22 is a diagram showing a range of cell conditions in which a good display contrast can be obtained when the twist angle is 265 degrees. FIG. 23 is a diagram showing a range of cell conditions in which good display contrast can be obtained when the twist angle is 270 degrees. FIG. 24 is a diagram illustrating spectral characteristics of the liquid crystal display element according to Example 1 of the present invention when the electric field is off and when the electric field is on. FIG. 25 is a diagram showing the spectral characteristics of the liquid crystal display element in Example 2 of the present invention when the electric field is off and when the electric field is on. FIG. 26 is a diagram showing the spectral characteristics of the liquid crystal display element in Example 3 of the present invention when the electric field is off and when the electric field is on. FIG. 27 is a sectional view of a conventional liquid crystal display device. FIG. 28 is a diagram illustrating spectral characteristics of a conventional liquid crystal display element when an electric field is off and when an electric field is on. [Explanation of Codes] 1. liquid crystal cell 2. Polarizing plate (upper side) 3. Polarizing plate (lower side) Reflector 11. Upper substrate 12. Lower substrate 13. Transparent electrode 14. 14. Reflective film also serving as pixel electrode Liquid crystal 16. Liquid crystal molecules 17. 21. Central plane of liquid crystal layer 22. Polarization axis (absorption axis or transmission axis) direction of polarizing plate 2 22. Rubbing direction of upper substrate 11 (liquid crystal alignment direction) Rubbing direction of lower substrate 12 (liquid crystal alignment direction) 31. Twist angle of liquid crystal 15 41. 42. Spectral characteristics of reflected light when electric field is off 51. Spectral characteristics of reflected light when electric field is on 52. Isocontrast curve with a contrast ratio of 1:20 Isocontrast curve with contrast ratio 1:10 53. Isocontrast curve with contrast ratio 1: 5

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 G02F 1/139

Claims (1)

(57) Claims 1. A twisted liquid crystal layer is sandwiched between a pair of substrates, and a polarizing means disposed on one of the substrates and the liquid crystal layer of the other substrate are provided. A reflection means having irregularities formed on the side thereof, wherein the luminous reflectance in the electric field off state is set higher than the luminous reflectance in the electric field on state, and the liquid crystal layer comprises: Light incident on the liquid crystal layer via the polarizing means in an electric field off state is converted into an elliptically polarized state in the liquid crystal layer, then converted into a substantially linearly polarized state and reaches the reflecting surface of the reflecting means. A liquid crystal display element characterized by being set.