JPH09236804A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce visual angle dependence ability and to enlarge a visual field angle in a liquid crystal display device. SOLUTION: A liquid crystal display element 16 has a liquid crystal layer 15 which is divided into two regions between a pair of glass substrates 8, 9 and the layer and the two regions have different visual angle dependence ability and twist angles ψ1 , ψ2 in the two regions satisfying a relation: ψ1 +ψ2 =180 deg.. At both sides of the liquid crystal display element 16, polarizing plates 6, 7 are installed that an absorption axis 2 of the polarizing plate 6 has an angle of ψ2 /2 to an orientation direction 4 of the glass substrate 8 and an absorption axis 3 of the polarizing plate 7 has an angle of ψ1 /2 to an orientation direction 5 of the glass substrate 9.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device that improves the viewing angle characteristics of a display screen.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device using a nematic liquid crystal display element has been widely used for a numerical segment type liquid crystal display device such as a clock and a calculator. Recently, it has been used as a television including a display of a word processor and a computer and a navigation system.

Generally, in such a liquid crystal display device, an active element such as a thin film transistor (hereinafter referred to as a TFT) is formed as a switching means for selectively driving a pixel electrode for applying a voltage to a liquid crystal layer. Further, in order to perform color display, color filter layers of red, green, blue and the like are provided. Also, as a display method,
The following two liquid crystal display systems are known according to the twist angle of the nematic liquid crystal used.

(A) Active drive type Twisted Nematic (hereinafter referred to as TN) liquid crystal display system in which nematic liquid crystal molecules are twisted and aligned by 90 °. (B) Twisted alignment by setting the twist angle of the nematic liquid crystal molecules to 90 ° or more. Multiplex drive type Super Twisted Nematic,
Liquid crystal display system (hereinafter referred to as STN) Incidentally, in the display devices of the above-mentioned two types of liquid crystal display systems, various improvement methods have been proposed due to the problems of viewing angle dependence and narrow viewing angle.

For example, in Japanese Patent Laid-Open No. 186735/1982, each picture element is divided into two areas, and the visual angle characteristics of these areas are made different to give each picture element a plurality of visual angle characteristics. Is proposed. In addition, Japanese Patent Application Laid-Open
Japanese Patent No. 248497 proposes a method in which a liquid crystal has a plurality of twist orientations in each picture element.

[0006]

Problems to be Solved by the Invention JP-A-57-1867
According to the method described in Japanese Patent No. 35, each picture element is
It will have two viewing directions, 12 o'clock and 6 o'clock. In a liquid crystal panel having such viewing angle characteristics, viewing angle dependence exists in the vertical direction (that is, 6 o'clock to 12 o'clock direction) and the horizontal direction (that is, 3 o'clock to 9 o'clock direction). In particular, the viewing angle dependency when viewing the display panel from the lateral direction (3 o'clock to 9 o'clock direction) is almost the same as that of the TN liquid crystal panel to which the conventional alignment division method is not applied. However, when the viewing angle is increased in the horizontal direction from the direction perpendicular to the liquid crystal panel (viewing angle 0 °), the gradation inversion phenomenon in which the black and white (contrast) of the image is reversed near the viewing angle 30 ° occurs. Occurs.

When the viewing angle is increased from 0 ° in the vertical direction, the viewing angle characteristic in the 6 o'clock direction and the viewing angle characteristic in the 12 o'clock direction in the conventional TN liquid crystal panel are averaged. Therefore, the viewing angle characteristics when the viewing angle is increased in the 12 o'clock direction and when the viewing angle is increased in the 6 o'clock direction are of interest. However, there is a limit to the increase in contrast when the viewing angle is tilted.

Further, in any of the methods described in the above two documents, there is a limit in improving the viewing angle characteristics in the azimuth angle of 45 ° from the absorption axis or the transmission axis of the polarizing plate.

The present invention has been made in view of the above circumstances, and an object thereof is a liquid crystal capable of eliminating the inversion phenomenon depending on the direction of arrangement of the polarizing plate and realizing a high image quality and a wide viewing angle characteristic. It is to provide a display device.

[0010]

A liquid crystal display device of the present invention is a liquid crystal display device having a plurality of display picture elements arranged in a matrix, and a pair of substrates facing each other.
A liquid crystal layer disposed between the pair of substrates and a surface of at least one of the pair of substrates facing the liquid crystal layer are formed, and a treatment for aligning liquid crystal molecules of the liquid crystal layer is performed. And a pair of polarizing plates arranged so as to sandwich the pair of substrates, the liquid crystal layer is divided into at least two regions in each of the display pixels, The alignment state of the liquid crystal molecules is different in at least two regions, and the absorption axis of one of the pair of polarizing plates is substantially parallel to the 6 o'clock to 12 o'clock direction or the 3 o'clock to 9 o'clock direction. The above object is achieved by.

Even if one absorption axis of the pair of polarizing plates is substantially parallel to the 6 o'clock to 12 o'clock direction and the other absorption axis is substantially parallel to the 3 o'clock to 9 o'clock direction. Good.

Another liquid crystal display device of the present invention is a liquid crystal display device having a plurality of display picture elements arranged in a matrix, wherein a pair of substrates facing each other and a pair of substrates are arranged between the pair of substrates. Liquid crystal layer, an alignment film formed on at least one surface of the pair of substrates facing the liquid crystal layer, and subjected to a treatment for aligning liquid crystal molecules of the liquid crystal layer; A pair of polarizing plates provided so as to sandwich the substrate, the liquid crystal layer is divided into two regions in each of the display picture elements, and the two regions have different viewing angle dependences. Therefore, the angles ψ1 and ψ2 (ψ) of the alignment directions formed by the respective liquid crystal molecules in contact with the upper and lower substrates.
1 + ψ2 = 180 °), one absorption axis of the pair of polarizing plates forms an angle of substantially ψ1 / 2, and the other absorption axis of the polarizing plates of the pair of substrates substantially forms ψ2. It forms an angle of / 2, which achieves the above object.

The angle formed by one absorption axis of the pair of polarizing plates and the other absorption axis may be 90 ° ± 5 °.

The operation will be described below.

According to the present invention, the effect of expanding the viewing angle in the horizontal direction can be obtained together with the expansion of the viewing angle in the vertical direction. Regarding the effect of widening the viewing angle, it is essential to improve the viewing angle in the lateral direction and the improvement of gradation inversion, depending on the shape of the screen shifting to the wide type and the condition when a person views the screen.

In a liquid crystal display device in which the liquid crystal orientation is divided into at least two regions or more in each picture element, the absorption axis of either of the upper and lower polarizing plates is almost 6 o'clock to 12 o'clock direction or 3 o'clock to 9 o'clock direction. By making the angle between the absorption axis of the polarizing plate and the absorption axis of the other polarizing plate 90 ° ± 5 ° in parallel, the contrast ratio in the horizontal direction as well as in the vertical direction can be set regardless of the characteristics of the polarizing plate. It is possible to realize a liquid crystal display device having a small change, a wide viewing angle and excellent visibility. Here, in the present specification, “dividing the liquid crystal alignment” means dividing the liquid crystal layer into a plurality of regions and making the alignment state of the liquid crystal molecules different between the regions.

Further, in a liquid crystal display device in which the liquid crystal orientation is divided into two regions in each picture element, the absorption axis of one of the polarizing plates is approximately equal to the angles ψ1 and ψ2 formed by the alignment directions of the liquid crystal molecules of the upper and lower substrates. The polarizing plate is set so that the absorption axis of the other polarizing plate is approximately φ2 / 2, and the angle between the absorption axis of one polarizing plate and the absorption axis of the other polarizing plate is 90. In the case of ° ± 5 °, gradation inversion in the horizontal direction is significantly eliminated regardless of the characteristics of the polarizing plate, and the viewing angle can be expanded in the vertical direction. Moreover, it is possible to make the changes in the contrast ratio in the vertical and horizontal directions similar.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited by this.

(Embodiment 1) FIG. 2 is a sectional view showing the structure of a liquid crystal display device 1 according to this embodiment. The liquid crystal display device 1 includes a liquid crystal display element 16 and a pair of polarizing plates 6 and 7 provided on both sides of the liquid crystal display element 16. The liquid crystal display element 16 is
Substrates are provided on both sides of the liquid crystal layer 15 in between, and one substrate (upper side in the figure) is a transparent electrode made of ITO (indium tin oxide) on the surface of the glass substrate 8 serving as a base on the liquid crystal layer 15 side. 10 is formed, and the alignment film 12 is formed thereon. On the other (lower side of the drawing), a transparent electrode 11 made of ITO is formed on the surface of the glass substrate 9 serving as a base on the liquid crystal layer 15 side, and an alignment film 13 is formed thereon. The picture element electrodes 10 and 11 are both formed with a predetermined width and at a predetermined interval, and are orthogonal to each other when viewed from the normal direction of the glass substrate 8 or 9. The portion where both picture element electrodes 10 and 11 overlap is a picture element that contributes to the display, and the picture elements are arranged in a matrix. In FIG. 2, 14 is a sealing resin for sealing the liquid crystal layer 15, and 17 is a drive circuit.

The alignment films 12 and 13 have been subjected to alignment treatment so that the liquid crystal molecules in contact therewith are aligned in the directions 4 and 5 shown in FIG. 1, respectively. The alignment film 12 has regions 12A and 12B whose states are different from each other, and the alignment film 13 has regions 13A and 13B whose states are different from each other. As a result, in the regions A and B of the liquid crystal layer 15, liquid crystal molecules The orientation state is controlled to be different. Specifically, for example, the pretilt angle of the liquid crystal molecules is controlled to be different between the region A and the region B, or the tilt directions of the liquid crystal molecules are controlled to be opposite to each other. Therefore, FIG.
In the liquid crystal display element 16 of, the liquid crystal layer 15 has two regions A and B.
It is a liquid crystal display element divided into two parts. It should be noted that any process may be used to make the alignment state of the liquid crystal molecules different between the regions. The states of the regions 12A, 12B, 13A and 13B of the alignment films 12 and 13 are the same as those of the liquid crystal layer 15
The regions A and B are controlled so that the alignment state of the liquid crystal molecules is different. Specifically, for example, the pretilt angles of the liquid crystal molecules are controlled so as to be different between the regions, or the tilt directions of the liquid crystal molecules are controlled to be opposite to each other.

In this embodiment, a liquid crystal material having a refractive index anisotropy Δn of 0.089 and a chiral dopant added is used as the material of the liquid crystal layer 15, and the layer thickness of the liquid crystal layer 15 is about 4.5 μm.
Set to. Further, the twist angle of the alignment direction of the liquid crystal molecules between both substrates 8 and 9 was set to ψ1 = ψ2 = 90 °. However, ψ1 and ψ2 are regions A and B of the liquid crystal layer 15, respectively.
And the twist angle at.

FIG. 1 is a view showing the installation direction of the polarizing plate of the liquid crystal display device 1 according to this embodiment. This liquid crystal display device 1
In, the polarizing plate 6 is installed so that the absorption axis 2 forms an angle ψ2 / 2 with respect to the alignment direction 4 of the liquid crystal molecules on the glass substrate 8 side, and the polarizing plate 7 has the absorption axis 3 on the glass substrate 9 side. It is installed so as to form an angle ψ1 / 2 with respect to the alignment direction 5 of the liquid crystal molecules. Further, the directions of the absorption axes 2 and 3 of the polarizing plates 6 and 7 may be rotated by 90 degrees. In this embodiment, ψ1 =
Since 90 ° and ψ2 = 90 °, the polarizing plate 6 is arranged so that the absorption axis 2 is 45 ° with respect to the alignment direction 4 of the liquid crystal molecules in contact with the glass substrate 8, and the polarizing plate 7 is the absorption axis. 3 was arranged at 45 ° with respect to the alignment direction 5 of the liquid crystal molecules in contact with the glass substrate 9.

Next, the results of measuring the viewing angle dependence of the liquid crystal display device 1 thus obtained will be described.

FIG. 3 is a schematic perspective view showing a measuring system of the viewing angle dependency of the liquid crystal display device 1. The surface 26 where the glass substrate 8 of the liquid crystal display element 16 which constitutes the liquid crystal display device 1 and the polarizing plate 6 are in contact with each other is set on the reference plane xy of the orthogonal coordinates xyz, and the normal direction 27 of the surface 26 is set. in the direction of θ,
A light receiving element 71 having a constant stereoscopic light receiving angle is arranged at a position a predetermined distance from the origin of coordinates, and a wavelength of 55
A monochromatic light of 0 nm is incident. The output of the light receiving element 71 is amplified to a predetermined level by an amplifier 72 and recorded by a recording means 73 such as a waveform memory or a recorder.

A liquid crystal display device 1 in which polarizing plates 6 and 7 are arranged so that their absorption axes 2 and 3 are orthogonal to each other is installed in the measurement system shown in FIG. 3 and the viewing angle dependence thereof is measured. . The measurement results are shown in FIGS. 4 and 5 as graphs of transmittance-liquid crystal applied voltage characteristics. FIG. 4 shows the result in the 6 o'clock direction.
In FIG. 4, line L1 is at an angle θ = 0 °, line L2 is at θ = 10 °, line L3 is at θ = 20 °, line L4 is at θ = 30 °, and line L5 is at θ.
The case of = 40 ° is shown. from this result,
Even when the voltage applied to the liquid crystal is gradually increased from 0 V and reaches 4 V which is a voltage used for normal display, the transmittance measured at the position of θ = 40 ° is 5% or less. As described above, it is understood that the viewing angle is expanded by setting the relationship between the alignment direction of the liquid crystal molecules in the liquid crystal layer 15 and the absorption axis of each polarizing plate as in the present embodiment. Also, 1
Similar results were obtained in the 2 o'clock direction.

FIG. 5 shows the result at 3 o'clock. In FIG. 5, when the line L6 has an angle θ = 0 °, the line L7 has a θ
= 10 °, the line L8 has θ = 20 °, the line L9 has θ = 30 °, and the line L10 has θ = 40 °.
Respectively. From this result, the liquid crystal applied voltage was gradually increased from 0V, and even when it reached 4V which is a voltage used for normal display, the transmittance measured at the position of θ = 40 ° was 10% or less, It is understood that the viewing angle is enlarged. Also, similar results were obtained in the 9 o'clock direction.

(Comparative Example 1) FIG. 7 is a sectional view showing the structure of a liquid crystal display device 51 according to this example. The liquid crystal display device 51 includes a liquid crystal display element 66 and a pair of polarizing plates 56 and 57 provided on both sides thereof. The liquid crystal display element 66 is provided with substrates on both sides of the liquid crystal layer 65, and one of the substrates (the upper side in the figure) has ITO (indium tin oxide) on the surface of the base glass substrate 58 on the liquid crystal layer 65 side. A transparent electrode 60 made of a material), and an alignment film 62 is formed thereon. The other (lower side of the figure) board is
I is formed on the surface of the liquid crystal layer 65 of the glass substrate 59 serving as a base.
A transparent electrode 61 made of TO is formed, and an alignment film 63 is formed thereon. The picture element electrodes 60 and 61 both have a predetermined width and are provided at a predetermined interval, and the glass substrate 58 is provided.
Alternatively, they are formed so as to be orthogonal to each other when viewed in the normal direction of 59. The portion where both picture element electrodes 60 and 61 overlap is a picture element that contributes to display, and the picture elements are arranged in a matrix. In FIG. 7, 64 is a liquid crystal layer 65.
67 is a sealing resin for sealing, and 67 is a drive circuit.

The alignment film 62 has regions 6 which are in different states.
2A and 62B, and the alignment film 63 also has regions 63A and 63B whose states are different from each other. As a result, the region 62A of the alignment film 62 and the region 63A of the alignment film 63 are formed.
A region of the liquid crystal layer 65 sandwiched between and, a region 62B and a region 6
The alignment state of the liquid crystal molecules is controlled so as to be different from the region of the liquid crystal layer 65 sandwiched between 3B and 3B. Specifically, for example, the pretilt angles of the liquid crystal molecules are controlled so as to be different between the regions, or the tilt directions of the liquid crystal molecules are controlled to be opposite to each other. Therefore, the liquid crystal display element 66 of FIG. 7 is a liquid crystal display element in which the liquid crystal layer 65 is divided into two regions by alignment division.

Also in this comparative example, a liquid crystal material having a refractive index anisotropy Δn of 0.089 and a chiral dopant added is used as the material of the liquid crystal layer 65, and the thickness of the liquid crystal layer 65 is about 4.
It was set to 5 μm.

FIG. 6 shows a liquid crystal display device 51 according to this comparative example.
It is a figure showing the installation direction of the polarizing plate. In the liquid crystal display device 51, the polarizing plate 56 is installed so that the absorption axis 52 is substantially parallel to the alignment direction 54 of the liquid crystal molecules in contact with the glass substrate 58, and the polarizing plate 57 has the absorption axis 53 of the glass substrate. It is installed so as to be substantially parallel to the alignment direction 55 of the liquid crystal molecules in contact with 59.

The liquid crystal display device 51 as described above was installed in the measurement system shown in FIG. 3 in the same manner as in Example 1, and the viewing angle dependency was measured. The measurement results are shown in FIGS. 8 and 9 as graphs of transmittance-liquid crystal applied voltage characteristics. FIG. 8 shows the result in the 6 o'clock direction. In FIG. 8, line L51 is at an angle θ = 0 °, line L52 is at θ = 10 °, line L53 is at θ = 20 °, line L54 is at θ = 30 °,
The line L55 shows the case of θ = 40 °. From FIG. 8, when the voltage applied to the liquid crystal is gradually increased to reach 4V which is a voltage value used for normal display, θ =
It is confirmed that the transmittance measured at the position of 40 ° is 10% or more. Similar results were obtained in the 12 o'clock direction.

FIG. 9 shows the result in the 3 o'clock direction. In FIG. 9, line L56 is line L57 when the angle θ = 0 °.
Shows the case where θ = 10 °, the line L58 shows the case where θ = 20 °, the line L59 shows the case where θ = 30 °, and the line L60 shows the case where θ = 40 °. From this result, when the liquid crystal applied voltage is gradually increased from 0 V, θ =
It is understood that the gradation inversion phenomenon appears at 30 ° and 40 °. Similar results were obtained in the 9 o'clock direction.

Therefore, in Example 1, the viewing angle dependency was remarkably improved as compared with that in Comparative Example 1, and the vertical direction (6 o'clock to 12 o'clock direction) and the horizontal direction (3 o'clock to 9 o'clock). It is understood that the viewing angle is expanded in both directions.

In Example 1, the liquid crystal display device 1 in which the polarizing plates 6 and 7 are arranged so that their absorption axes 2 and 3 are substantially orthogonal to each other has been described as an example, but the absorption axes 2 and 3 are 90 °.
An angle in the range of ± 5 °, and twist angles ψ1, ψ2 in the regions A and B are ψ1 + ψ2 = 180 °,
The same effect can be obtained when the polarizing plates 6 and 7 are arranged so as to satisfy the above relationship.

Although the simple matrix type liquid crystal display device has been described in the first embodiment, the case where the polarizing plate is installed as in the first embodiment in the active matrix liquid crystal display device using the active switching elements such as TFTs. Also has the same effect.

(Embodiment 2) FIG. 11 is a sectional view showing the structure of a liquid crystal display device 101 according to this embodiment. The liquid crystal display device 101 includes a liquid crystal display element 116 and a pair of polarizing plates 106 and 107 provided on both sides thereof.
The liquid crystal display element 116 has substrates provided on both sides of the liquid crystal layer 115, and one substrate (upper side in the drawing) has an I surface on the liquid crystal layer 115 side of a glass substrate 108 serving as a base.
A transparent electrode 110 made of TO (indium tin oxide) is formed, and an alignment film 112 is formed thereon. The other (lower side of the figure) substrate is the glass substrate 10 serving as a base.
9, a transparent electrode 1 made of ITO on the surface of the liquid crystal layer 115 side.
11 is formed, and the alignment film 113 is formed thereon. The picture element electrodes 110 and 111 each have a predetermined width and are provided at predetermined intervals, and the glass substrate 108 or 1
They are formed so as to be orthogonal to each other when viewed from the normal direction of 09. The portion where both picture element electrodes 110 and 111 overlap is a picture element that contributes to display, and the picture elements are arranged in a matrix. In addition, 114 in FIG. 11 is the liquid crystal layer 1.
Reference numeral 117 denotes a sealing resin for sealing 15 and 117 denotes a drive circuit.

The alignment films 112 and 113 are respectively subjected to a treatment for aligning liquid crystal molecules by irradiation of ultraviolet rays or a special alignment treatment. Thereby, the alignment film 11
The liquid crystal molecules in contact with 2, 113 are controlled so as to be aligned in different directions in a plurality of regions of each alignment film, or to be radially or randomly aligned. Alternatively, it may be controlled to have a random twist angle. Since the alignment films 112 and 113 are subjected to such a treatment, the liquid crystal display element 116 is a liquid crystal display element in which the alignment state of liquid crystal molecules is different in a plurality of regions of the liquid crystal layer 115.

In this embodiment, a liquid crystal material having a refractive index anisotropy Δn of 0.089 and a chiral dopant added is used as the material of the liquid crystal layer 115, and the thickness of the liquid crystal layer 115 is set to about 4.5 μm. Set.

FIG. 10 shows a liquid crystal display device 1 according to this embodiment.
It is the figure which showed the installation direction of the polarizing plate of No. 01. In the liquid crystal display device 101, the absorption axis 102 of the polarizing plate 106
Are installed so as to be substantially parallel to the 6 o'clock to 12 o'clock direction, and the absorption axis 103 of the polarizing plate 107 is installed to be substantially parallel to the 3 o'clock to 9 o'clock direction.

The liquid crystal display device 101 as described above was installed in the measurement system shown in FIG. 3 in the same manner as in Example 1, and the viewing angle dependence was measured. The measurement results are shown in FIG. 12 as a graph of transmittance-liquid crystal applied voltage characteristic. FIG. 12 shows the result in the 6 o'clock direction. In FIG. 12, the line L11 has an angle θ = 0.
In case of θ, the line L12 is in case of θ = 10 °.
13 shows the case where θ = 20 °, the line L14 shows the case where θ = 30 °, and the line L15 shows the case where θ = 40 °. From FIG. 12, when the voltage applied to the liquid crystal is gradually increased from 0 V and the voltage value used for normal display reaches 4 V, the transmittance measured at the position of θ = 40 ° is about 5%.
% Is confirmed. Similar results were also obtained for the 12 o'clock, 3 o'clock, and 9 o'clock directions.

(Comparative Example 2) FIG. 14 is a sectional view showing the structure of a liquid crystal display device 201 according to this example. The liquid crystal display device 201 includes a liquid crystal display element 216 and a pair of polarizing plates 206 and 207 provided on both sides thereof.
Substrates are provided on both sides of the liquid crystal display element 216 and the liquid crystal layer 215, and one of the substrates (the upper side in the drawing) has an IT on the surface of the glass substrate 208 serving as a base on the liquid crystal layer 215 side.
A transparent electrode 210 made of O (indium tin oxide) is formed, and an alignment film 212 is formed thereon. The other substrate (lower side of the figure) is a glass substrate 209 serving as a base.
On the surface of the liquid crystal layer 215 side of the transparent electrode 21 made of ITO
1 is formed, and the upper alignment film 213 is formed thereon. The picture element electrodes 210 and 211 each have a predetermined width and are provided at predetermined intervals, and the glass substrate 208 or 2 is used.
They are formed so as to be orthogonal to each other when viewed from the normal direction of 09. The portion where both picture element electrodes 210 and 211 overlap is a picture element that contributes to display, and the picture elements are arranged in a matrix. In FIG. 14, 214 is the liquid crystal layer 2.
Reference numeral 217 is a sealing resin for sealing 15 and 217 is a drive circuit.

The alignment films 212 and 213 are respectively subjected to a treatment for aligning liquid crystal molecules by irradiation with ultraviolet rays or a special alignment treatment. Thereby, the alignment film 21
The liquid crystal molecules in contact with 2, 213 are controlled so as to be oriented in different directions in a plurality of regions of each orientation film, or to be radially or randomly oriented. Alternatively, it may be controlled to have a random twist angle. Since the alignment films 212 and 213 are subjected to such a treatment, the liquid crystal display element 216 is a liquid crystal display element in which the alignment state of liquid crystal molecules is different in a plurality of regions of the liquid crystal layer 215.

Also in this comparative example, a liquid crystal material having a refractive index anisotropy Δn of 0.089 and a chiral dopant added was used as the material of the liquid crystal layer 215, and the thickness of the liquid crystal layer 215 was set to about 4.5 μm. .

FIG. 13 shows a liquid crystal display device 2 according to this comparative example.
It is the figure which showed the installation direction of the polarizing plate of No. 01. In the liquid crystal display device 201, the polarizing plate 206 has an absorption axis 202.
Is approximately 45 ° with respect to the 6 o'clock to 12 o'clock direction of the liquid crystal display element 216.
The polarizing plate 207 has an absorption axis 203.
Is installed at an angle of 45 ° with respect to 3 o'clock to 9 o'clock.

Such a liquid crystal display device 201 is used in the first embodiment.
Similarly to the above, the measurement system was installed in the measurement system shown in FIG. 3 and its viewing angle dependence was measured. The measured results are shown in FIG. 15 as a graph of transmittance-liquid crystal applied voltage characteristic. FIG. 15 shows the result in the 6 o'clock direction. In FIG. 15, the line L61 has an angle θ = 0 °.
In case of θ = 10 °, the line L62 is
3 shows the case where θ = 20 °, the line L64 shows the case where θ = 30 °, and the line L65 shows the case where θ = 40 °. From FIG. 15, when the liquid crystal applied voltage is gradually increased from 0 V and reaches 4 V which is a voltage value normally used for display, the transmittance measured at the position of θ = 40 ° is 10%.
The above is confirmed. Similar results were also obtained for the 12 o'clock, 3 o'clock, and 9 o'clock directions.

Therefore, the example 2 is the same as the comparative example 2.
It is understood that the viewing angle characteristics in the 6 o'clock to 12 o'clock direction and the 3 o'clock to 9 o'clock direction are considerably improved and the visibility is excellent as compared with the above-mentioned one.

In the second embodiment, the polarizing plates 106 and 10 are used.
The liquid crystal display device in which 7 is installed so that the absorption axes 102 and 103 are parallel to the 6 o'clock to 12 o'clock direction and the 3 o'clock to 9 o'clock direction has been described as an example. The absorption axis 103 is parallel to the direction
2 and 90 ° ± 5 °, and the absorption axis 103 is parallel to the 3 o'clock-9 o'clock direction,
The same effect can be obtained even when forms an angle in the range of 90 ° ± 5 ° with the absorption axis 103.

In the second embodiment, the liquid crystal display element 116 is used.
The case where is a simple matrix type has been described as an example.
Similar results can be obtained even in the case of an active matrix type using an active switching element such as a TFT.

[0049]

As described above, according to the present invention,
Along with vertical viewing angle expansion, the effect of horizontal viewing angle expansion is obtained, and it is essential for improving the horizontal viewing angle expansion and gradation reversal from the shape of the screen that shifts to the wide type and the condition when people look at the screen. Can meet the conditions of.

In a liquid crystal display device in which the liquid crystal orientation is divided into at least two regions or more in each picture element, the absorption axis of either the upper or lower polarizing plate is almost 6 o'clock to 12 o'clock direction or 3 o'clock to 9 o'clock direction. By setting the angle between the absorption axis of the polarizing plate and the absorption axis of the other polarizing plate to be 90 ° ± 5 ° in parallel, the contrast ratio in the horizontal direction as well as in the vertical direction can be set regardless of the characteristics of the polarizing plate. It is possible to realize a liquid crystal display device having a small change, a wide viewing angle and excellent visibility.

Further, in the liquid crystal display device in which the liquid crystal orientation is divided into two regions in each picture element, the absorption axis of one of the polarizing plates is almost equal to the angles ψ1 and ψ2 formed by the orientation directions of the liquid crystal molecules of the upper and lower substrates. The polarizing plate is set so that the absorption axis of the other polarizing plate is approximately φ2 / 2, and the angle between the absorption axis of one polarizing plate and the absorption axis of the other polarizing plate is 90. In the case of ° ± 5 °, gradation inversion in the horizontal direction is significantly eliminated regardless of the characteristics of the polarizing plate, and the viewing angle can be expanded in the vertical direction. Moreover, it is possible to make the changes in the contrast ratio in the vertical direction and in the horizontal direction substantially the same.

Therefore, the display quality of the liquid crystal display device can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an installation direction of a polarizing plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a liquid crystal display device 1 which is an embodiment according to the present invention.

FIG. 3 is a schematic perspective view showing a measuring system of a viewing angle dependency of a liquid crystal display device.

FIG. 4 is a graph showing no transmittance-liquid crystal applied voltage characteristic in the 6 o'clock direction of the liquid crystal display device 1 in Example 1.

FIG. 5 is a graph showing transmittance-liquid crystal applied voltage characteristics in the 3 o'clock direction of the liquid crystal display device 1 in Example 1.

FIG. 6 is a plan view showing the installation direction of polarizing plates in Comparative Example 1.

7 is a cross-sectional view showing a liquid crystal display device 51 in Comparative Example 1. FIG.

8 is a graph showing the 6 o'clock direction transmittance-liquid crystal applied voltage characteristic of the liquid crystal display device 51 in Comparative Example 1. FIG.

9 is a graph showing transmittance-liquid crystal applied voltage characteristics in the 3 o'clock direction of the liquid crystal display device 51 in Comparative Example 1. FIG.

FIG. 10 is a plan view showing an installation direction of a polarizing plate which is another embodiment according to the present invention.

FIG. 11 is a cross-sectional view showing a liquid crystal display device 101 which is another embodiment of the present invention.

FIG. 12 is a graph showing transmittance-liquid crystal applied voltage characteristics in the 6 o'clock direction of the liquid crystal display device 101 in Example 2.

13 is a plan view showing the installation direction of polarizing plates in Comparative Example 2. FIG.

14 is a cross-sectional view showing a liquid crystal display device 201 in Comparative Example 2. FIG.

15 is a graph showing the 6 o'clock direction transmittance-liquid crystal applied voltage characteristic of the liquid crystal display device 201 in Comparative Example 2. FIG.

[Explanation of symbols]

1, 51, 101, 201 Liquid crystal display device 6, 7, 56, 57, 106, 107, 206, 207
Polarizing plates 8, 9, 58, 59, 108, 109, 208, 209
Glass substrate 10, 11, 60, 61, 110, 111, 210, 2
11 transparent electrodes 12, 13, 62, 63, 112, 113, 212, 2
13 Alignment film 14, 64, 114, 214 Sealing material 15, 65, 115, 215 Liquid crystal layer

Claims (4)

[Claims] 1. A liquid crystal display device having a plurality of display picture elements arranged in a matrix, comprising a pair of substrates facing each other, a liquid crystal layer arranged between the pair of substrates, and the pair of substrates. And an alignment film formed on at least one surface of the substrate facing the liquid crystal layer, which has been subjected to a treatment for aligning liquid crystal molecules of the liquid crystal layer, and is disposed so as to sandwich the pair of substrates. A pair of polarizing plates,
The liquid crystal layer is divided into at least two regions or more in each of the display pixels, and the alignment state of the liquid crystal molecules is different in the at least two regions. A liquid crystal display device in which one absorption axis is substantially parallel to the 6 o'clock to 12 o'clock direction or the 3 o'clock to 9 o'clock direction. 2. The absorption axis of one of the pair of polarizing plates is substantially parallel to the 6 o'clock to 12 o'clock direction, and the other absorption axis is substantially parallel to the 3 o'clock to 9 o'clock direction. The liquid crystal display device according to claim 1. 3. A liquid crystal display device having a plurality of display picture elements arranged in a matrix, comprising a pair of substrates facing each other, a liquid crystal layer arranged between the pair of substrates, and the pair of substrates. And an alignment film formed on at least one surface of the substrate facing the liquid crystal layer, which has been subjected to a treatment for aligning liquid crystal molecules of the liquid crystal layer, and is provided so as to sandwich the pair of substrates. A pair of polarizing plates,
The liquid crystal layer is divided into two regions in each of the display picture elements, and the two regions have different viewing angle dependences, and each of the liquid crystals is in contact with the upper and lower substrates. Orientation angles formed by molecules ψ1, ψ2 (ψ1 + ψ2 = 180
°), one absorption axis of the pair of polarizing plates forms an angle of substantially ψ1 / 2, and the other absorption axis of the polarizing plates of the pair of substrates substantially forms ψ2 / 2. Liquid crystal display device making an angle. 4. The liquid crystal display device according to claim 1, wherein an angle formed by one absorption axis of the pair of polarizing plates and the other absorption axis is 90 ° ± 5 °.