JP2000206535A - Transmissive hybrid aligned liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid aligned liquid crystal display device with high response speed of a liquid crystal layer. SOLUTION: The transmissive hybrid aligned liquid crystal display device comprises a liquid crystal layer 39 which is arranged between a first and a second transparent substrate 11a, 11b placed opposite to each other, of which the liquid crystal molecules on the first transparent substrate 11a side are almost vertically aligned with respect to the surface of the first transparent substrate 11a and also of which the liquid crystal molecules on the second transparent substrate 11b side are aligned almost in parallel with the surface of the second transparent substrate 11b and a pair of electrodes 12a, 12b which applies a driving voltage to the liquid crystal layer 39. In this case, the minimum driving voltage is set to be >1 V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transmissive hybrid alignment liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, hybrid alignment liquid crystal display devices have been proposed. The hybrid alignment liquid crystal display device is disposed between first and second transparent substrates facing each other, and liquid crystal molecules on the first transparent substrate are aligned substantially perpendicularly to the surface of the first transparent substrate. In addition, the liquid crystal display device has a liquid crystal layer in which liquid crystal molecules on the second transparent substrate are oriented substantially parallel to the surface of the second transparent substrate.

This hybrid alignment liquid crystal display device has a high response speed. When the voltage applied to the liquid crystal layer by a pair of electrodes is on, the response speed is fast, but when the voltage is off, the response speed is not so fast. . Also, switching to a gray level in which the drive voltage is low is not quick.

In order to increase the response speed of such a liquid crystal display device, it is sufficient to narrow the panel gap dlc of the liquid crystal layer. However, if the panel gap dlc is narrowed, the production yield of the liquid crystal display device decreases.

[0005] In the case of a hybrid alignment liquid crystal display device, there is no threshold value. Although the response is somewhat improved by setting the voltage of about several volts to the minimum off-voltage of the driving voltage, the minimum voltage of the driving voltage needs to be higher than 1 V in order to greatly improve the off-speed. is there. In almost all liquid crystal mode liquid crystal display devices, the on-off switching speed does not always increase even if the off-voltage of the driving voltage is increased. For example, in the current mainstream liquid crystal display device of the TN (twisted nematic) mode, when the off-voltage of the drive voltage is set higher than the threshold voltage, the off-on switching speed is increased, but the on-off switching speed is reversed. It will be late.

[0006]

SUMMARY OF THE INVENTION In view of the above, the present invention aims to propose a transmission type hybrid alignment liquid crystal display device having a high response speed of a liquid crystal layer.

Further, according to the present invention, the response speed of the liquid crystal layer is high,
Moreover, the present invention aims to propose a transmission type hybrid alignment liquid crystal display device having a wide viewing angle and high contrast.

[0008]

According to a first aspect of the present invention, there is provided a transmissive hybrid alignment liquid crystal display device disposed between first and second transparent substrates opposed to each other, and liquid crystal molecules on the first transparent substrate side. Are oriented substantially perpendicular to the surface of the first transparent substrate, and molecules of liquid crystal on the side of the second transparent substrate are oriented substantially parallel to the surface of the second transparent substrate; In a transmission type hybrid alignment liquid crystal display device having a pair of electrodes for applying a drive voltage to the liquid crystal layer, the minimum drive voltage is set higher than 1V.

According to the first aspect of the present invention, a state in which the minimum drive voltage is applied by the transparent electrode, that is, an off state (dark state in normally black, white state in normally white) By applying a voltage equal to or higher than a certain threshold value to the liquid crystal layer in (2) to cause the liquid crystal molecules in the horizontal direction to stand in the vertical direction, a high response speed can be realized.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The first invention is arranged between first and second transparent substrates facing each other, and liquid crystal molecules on the first transparent substrate side are disposed on the surface of the first transparent substrate. The liquid crystal layer is oriented substantially perpendicular to the second transparent substrate and the liquid crystal molecules are oriented substantially parallel to the surface of the second transparent substrate. In the transmission type hybrid alignment liquid crystal display device having
This is a transmissive hybrid alignment liquid crystal display device in which the minimum drive voltage is set higher than 1V.

According to a second aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the first aspect of the present invention, wherein a biaxial retardation plate for optical compensation is provided, and the biaxial retardation plate is provided. An axis perpendicular to the surface is z, an axis having a larger principal refractive index in the axial direction is x, and a smaller axis is a y-axis among two axes orthogonal to each other in a direction parallel to the plate surface. , X-axis, y
The principal refractive indices in the axial and z-axis directions are _nx , _ny , and _nz , respectively.
And when the thickness of the biaxial retardation plate is d,
A birefringence [Delta] n and the cell gap dlc of the liquid crystal layer, the relationship between the biaxial retardation plate, when the display of the normally white, Δn × dlc × 0.02 <( n x -n y) × d <Δn × dl
c × 0.2 Δn × dlc × 0.25 <(n x -n z) × d <Δn × dl
c is _{× 1 3 <(n x -n} z) ÷ (n x -n y) and set transmission hybrid alignment liquid crystal display device which is so.

According to a third aspect of the present invention, there is provided a transmission type hybrid alignment liquid crystal display device according to the first aspect of the present invention, wherein a biaxial retardation plate for optical compensation is provided, and the biaxial retardation plate is provided. An axis perpendicular to the surface is z, an axis having a larger principal refractive index in the axial direction is x, and a smaller axis is a y-axis among two axes orthogonal to each other in a direction parallel to the plate surface. , X-axis, y
The principal refractive indices in the axial and z-axis directions are _nx , _ny , and _nz , respectively.
And when the thickness of the biaxial retardation plate is d,
A birefringence [Delta] n and the cell gap dlc of the liquid crystal layer, the relationship between the biaxial retardation plate, when the display of a normally _{black, 150nm <(n x -n y} ) × d <350nm Δn × dlc × 0. _{1 <(n x -n z)} × d <Δn × dlc
A transmissive hybrid alignment liquid crystal display device set to be × 0.5.

According to a fourth aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the first aspect of the invention, wherein the liquid crystal layer is divided into different liquid crystal alignment directions.

According to a fifth aspect of the present invention, there is provided the transmissive hybrid alignment liquid crystal display device according to the second aspect of the present invention, wherein the liquid crystal layer is divided into different liquid crystal alignment directions.

According to a sixth aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the third aspect of the invention, wherein the liquid crystal layer is divided into different liquid crystal alignment directions.

According to a seventh aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the fourth aspect of the present invention, wherein
This is a transmissive hybrid alignment liquid crystal display device divided into different liquid crystal alignment directions.

According to an eighth aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the fifth aspect of the present invention, wherein
This is a transmissive hybrid alignment liquid crystal display device which is divided into different liquid crystal alignment directions and in which the y-axis direction of the biaxial retardation plate substantially matches the alignment direction substantially horizontal to the surface of the liquid crystal layer.

According to a ninth aspect of the present invention, there is provided a transmission type hybrid alignment liquid crystal display device according to the sixth aspect, wherein
This is a transmissive hybrid alignment liquid crystal display device which is divided into different liquid crystal alignment directions and in which the y-axis direction of the biaxial retardation plate substantially matches the alignment direction substantially horizontal to the surface of the liquid crystal layer.

According to a tenth aspect of the present invention, there is provided the transmission type hybrid alignment liquid crystal display device according to the second aspect of the present invention, wherein the liquid crystal layer and the biaxial phase difference plate have a Δn ×
This is a transmissive hybrid alignment liquid crystal display device in which the difference between dlc and (nx-ny) is set to a value in the range of 130 nm to 300 nm.

According to an eleventh aspect of the present invention, there is provided a transmission type hybrid alignment liquid crystal display device according to the third aspect of the present invention, wherein the liquid crystal layer and the biaxial phase difference plate have a Δn ×
This is a transmissive hybrid alignment liquid crystal display device in which the difference between dlc and (nx-ny) is set to a value in the range of 130 nm to 300 nm.

According to a twelfth aspect, in the transmission type hybrid alignment liquid crystal display device according to the second aspect, the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. It is.

According to a thirteenth aspect, in the transmission type hybrid alignment liquid crystal display device according to the third aspect, the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. It is.

According to a fourteenth aspect, in the transmission type hybrid alignment liquid crystal display device according to the second aspect, the cell gap dlc of the liquid crystal layer is set to a value in the range of 2.5 μm <dlc <5 μm. This is a transmission type hybrid alignment liquid crystal display device.

According to a fifteenth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the third aspect of the present invention, the cell gap dlc of the liquid crystal layer is set to a value in the range of 2.5 μm <dlc <5 μm. This is a transmission type hybrid alignment liquid crystal display device.

[Specific Example of Embodiment of the Invention] A transmissive hybrid alignment liquid crystal display device according to a specific example of the embodiment of the present invention will be described below with reference to FIG. In FIG. 1, external light from below the polarizing plate 42b is incident on the liquid crystal display device as if it were incident on the polarizing plate 42b. First, the alignment film 1
3a and 13b will be described. The alignment film 13a is an alignment film that aligns the liquid crystal molecules 40 on the transparent substrate 11a side of the liquid crystal layer 39 substantially perpendicular to the substrate surface.
Is an alignment film for aligning the liquid crystal molecules 40 of the liquid crystal layer 39 on the transparent substrate 11b side substantially parallel to the substrate surface.

When the alignment film 13b is not divided, a soluble polyimide alignment film is applied by spin coating to a thickness of about 50 nm on the transparent electrode 12b on the transparent substrate 11b. Rubbing is performed at 0.2 mm. When the pretilt of the transparent substrate 11b on which the alignment film 13b was formed was measured, the pretilt was about 3 °.

The alignment film 13a is formed by applying a vertical alignment type polyimide alignment film to the biaxial retardation plate 52 via the transparent electrode 12a on the transparent substrate 11a by spin coating so as to have a thickness of about 50 nm. May be slightly tilted in the same direction as the counter substrate 11b by a rubbing process so that is stable.

The transparent substrates 11a and 11b on which the alignment films 13a and 13b are formed, respectively, have a birefringence Δn of 0.161, Δε of 8, k11 of 11.8, k22 of 5.4, and k33 of 15. By using the liquid crystal layer 39 made of a nematic liquid crystal containing no chiral agent, a liquid crystal cell 41 in which the cell gap dlc of the liquid crystal layer 39 is 3.7 μm can be obtained. Where k11, k22, k
Reference numeral 33 denotes the splay, twist and bend elastic constants, respectively. Note that the cell gap dlc of the liquid crystal layer 39 is
Set to a value within the range of 2.5 μm <dlc <5 μm.

When the ON voltage of the drive voltage applied to the liquid crystal layer 39 of the liquid crystal cell 41 is higher than 4.5 V and the OFF voltage is higher than 1 V, preferably higher than 1.5 V by the transparent electrodes 12 a and 12 b, The response speed from off to on is significantly improved. That is, the response speed from on to off when the off voltage is 0 V is 20 msec, the response speed when the off voltage is 1 V is 18 msec, and the response speed when the off voltage is 1.5 V is 12 msec. Is 2 mV, the response speed is 8 msec, and the off-state voltage is 3 msec.
When V is V, this response speed is 5 msec. It can be seen that the response speed increases as the off-voltage increases.

Reference numerals 11a and 11b denote parallel plate-shaped transparent substrates, for example, glass substrates. The liquid crystal layer 3 is provided on the upper surface of the transparent substrate 11a and the lower surface of the transparent substrate 11b.
Polarizing plates 42 having a polarization direction deviated by 45 ° from the alignment direction of No. 9 so as to be crossed with each other.
a and 42b are arranged.

The lower surface of the transparent substrate 11a and the transparent substrate 1
On the upper surface of 1b, ITO (Indium tin ox)
ide: transparent electrode 12 made of an alloy of indium and tin)
a and 12b are arranged. An alignment film 13a is provided on the lower surface of the transparent electrode 12a, and the transparent electrode 12b
The alignment film 13b is directly disposed on the upper surface of the substrate. The liquid crystal layer 39 sealed by the sealing portion 39S is provided between the alignment films 13a and 13b. In these alignment films 13a and 13b, the sealing layer 39S and the liquid crystal layer 39,
A liquid crystal cell is configured.

As the liquid crystal layer 39, birefringence (the magnitude of birefringence) Δn (= n ₁ −n ₂ ) (where n ₁ is the refractive index when the electric vector of light vibrates in the optical axis direction, n ₂ indicates the refractive index when the electric vector of light oscillates in the direction perpendicular to the optical axis), but Δn> 0.15, for example, 0.161,
The magnitude of the dielectric anisotropy Δε is 8, k11 is 11.8, k
A nematic liquid crystal having 5.4 of 22 and k33 of 15 and containing no chiral agent was used.

The transparent substrate 11b can also be provided with a TFT (thin film transistor) and a MIM (insulator-metal-insulator) two-terminal element. Also, the transparent substrate 11a, or
Three color filters of red, green and blue can be provided on 11a and 11b.

The transmission type hybrid alignment liquid crystal display device of this embodiment will be further described with reference to FIG. Polarizing plates 42a and 42b are arranged on both sides of the liquid crystal cell 41 such that the polarizing axes 45 and 44 of the polarizing plates 42a and 42b are orthogonal to each other. Here, arrows 43a and 43b indicate
2 shows two types of orientation directions of the liquid crystal molecules 40 in the plane of the polarizing plate 43. Arrow 43a and polarization axis 4 of each polarizing plate 42a, 42b
When the angle β formed between the liquid crystal display device and the liquid crystal display device is approximately 45 degrees, the maximum transmittance of the liquid crystal display device can be maximized. Then, a biaxial retardation plate 52 for optical compensation is arranged between the polarizing plate 42a and the transparent substrate 11a.

The biaxial retardation plate 52 has biaxial refractive index anisotropy. An axis in the direction perpendicular to the plate surface is z, and an axis having a larger principal refractive index in the axial direction is x and a smaller axis is y among two axes orthogonal to each other in a direction parallel to the plate surface.
Axis. x-axis and alignment direction 43a, 43 of liquid crystal molecules 40
b are arranged orthogonally.

In the drawing, as shown on the left side of the biaxial retardation plate 52, the main refractive indices in the x-axis, y-axis, and z-axis directions are _nx ,
n _y, expressed as n _z, which have a relation of _{n x> n y> n z} .

When the thickness of the biaxial retardation plate 52 is d, the birefringence Δn of the liquid crystal layer 39 and the cell gap dl
and c, the relationship between the biaxial retardation plate, when the normally white display (displaying white at a low voltage side) is, Δn × dlc × 0.02 <( n x -n y) × d < Δn × dl
c × 0.2 Δn × dlc × 0.25 <(n x -n z) × d <Δn × dl
_{c × 1 3 <(n x} -n z) ÷ (n x -n y) , and the case of normally black display (displaying black at a low voltage _{side), 150nm <(n x -n y} ) × d <350 nm (550
nm retardation of light) Δn × dlc × 0.1 <( n x -n z) × d <Δn × dlc
Set to be × 0.5.

[0038] Then, the biaxial retardation plate 52 _{specifically, (n x -n y) ×} d is _{40 (nm), (n x} -
_nz ) × d is 380 (nm), and the liquid crystal layer 3
9 on the side of the transparent substrate 11b so as to substantially coincide with the substantially horizontal orientation direction. Thereby, contrast> 10
The range in the left-right direction (direction ± 90 ° with respect to the rubbing direction) has expanded from approximately 25 ° to 50 °.

Next, with reference to FIG. 3, a description will be given of an alignment processing method when the alignment film 113b on the transparent substrate 11b of the specific example of the liquid crystal display device is divided and aligned. The substrate 11b in FIGS. 3A to 3D is obtained by extracting one pixel region from the substrate of the entire liquid crystal display device. As the alignment film 13b,
An alignment treatment is performed by a light irradiation method using a photosensitive molecular film. The photosensitive molecular film is a polymer material that causes some structural change when irradiated with light, and includes a so-called light polarization storage film. When the photosensitive molecular film serving as the alignment film 13b absorbs the polarized light, the film aligns the liquid crystal molecules in a direction perpendicular to the direction of polarization of the absorbed light, or aligns the liquid crystal molecules parallel to the polarization direction of the absorbed light. There are films of a type that causes the liquid crystal molecules to be oriented parallel to the polarization direction of the absorbed light.

As shown in FIG. 3A, polyvinyl cinnamate is applied on the transparent substrate 11b (actually, on the transparent electrode 12b thereon) by a spinner so as to have a thickness of about 100 nm to form an alignment film 13b. I do. The transparent substrate 11
The electrode on b is not shown.

The surface of the alignment film 13b made of polyvinyl cinnamate is irradiated with polarized ultraviolet light having a wavelength band of 250 nm to 330 nm. As shown in the drawing, when the horizontal direction in the drawing of the transparent substrate 11b is x-axis, the depth direction is y-axis, and the normal direction of the transparent substrate 11b is z-axis, y
The irradiation light 20 polarized in the z-plane direction is irradiated from the + z-axis direction to the entire surface of the transparent substrate 11b for about 50 seconds. The polyvinyl cinnamate film is provided with an orientation for orienting the polymer in the in-plane x-axis direction of the transparent substrate 11b.

As shown in FIG. 3B, the polyvinyl cinnamate film in a half area of each pixel is shielded from light by a 150 μm-thick striped photomask 22a. The irradiation light 21 having a deflection direction orthogonal to the deflection direction of the irradiation light 20, that is, the polarization direction in the xz plane, is incident on the alignment film surface at an incident angle θi.
Then, irradiation is performed obliquely in the −x-axis direction.

As shown in FIG. 3C, the photomask 22a
Is removed, and instead, a photomask 22b that shields a region previously irradiated with ultraviolet light is formed. Where xz
Irradiation light 23 having an in-plane polarization direction is irradiated obliquely toward the + x-axis direction opposite to the irradiation light 21 at an incident angle θi with respect to the alignment film surface. Thereafter, the photomask 22b is removed. The directions of the optical axes of the incident light axes of the irradiation lights 21 and 22 projected on the surface of the transparent substrate 11b are different from each other by 180 °.

As shown in FIG. 3D, in one pixel area of the alignment film 13b, the right half area in the figure irradiated with the irradiation lights 20 and 21 has a size corresponding to the incident angle θi of the irradiation light 21. Dependent pretilt angle δ and transparent substrate 11 in + x axis direction
The liquid crystal molecules 24a are given an orientation that gives the in-plane direction of b to the liquid crystal molecules 24a. On the other hand, in the left half region in the figure where the irradiation lights 20 and 23 are irradiated, a pre-titre angle δ depending on the incident angle θi of the irradiation light 23 and the transparent substrate 11b in the −x-axis direction are provided.
Is given to the liquid crystal molecules 24b. That is, two types of alignment regions in which the in-plane alignment directions of the transparent substrate 11b are different from each other by 180 ° are formed for each pixel of the polyvinyl cinnamate film. Note that the in-plane alignment directions of the transparent substrate 11b applied to the alignment film 13b are not different directions for each pixel, but are two directions in which the alignment directions formed in any of the pixels are uniform.

In the following, an alignment region provided with an in-plane alignment direction in the plane of the transparent substrate 11b in a single direction is called a domain. As the alignment film 13b, a polyimide film, a PVA film, a polypyrrole film, or the like, which performs alignment processing by rubbing, may be used other than the photosensitive polymer film. In this case, in order to form two types of domains in which the in-plane orientation directions of the transparent substrate 11b are different from each other by 180 ° in one pixel region, it is necessary to cover a half region of the pixel region with a resist mask or the like on the transparent substrate 11b. Rub in one direction. After that, the resist mask is peeled off, half of the exposed pixel region is covered with the resist mask, and rubbing is performed on the transparent substrate 11b in a direction opposite to the above.

In addition to the above, various alignment films and alignment control methods that have a pretiter and can impart alignment substantially parallel to the surface of the transparent substrate 11b to liquid crystal molecules can be used.
In addition, a method in which a slit is provided in an electrode for each pixel region and the alignment of liquid crystal molecules is controlled by the generated electric field can be used.

Incidentally, the alignment treatment by the light irradiation method is effective when an active element which is easily damaged by electrostatic discharge is formed on the transparent substrate 11b in order not to generate static electricity due to the rubbing of the surface of the transparent substrate 11b.

The transparent substrate 11b having the divided horizontal alignment film 13b obtained in this way, the transparent substrate 11a having the vertical alignment film 13a described above, and the liquid crystal layer 39 are combined to provide a 180 ° tilt direction. Are obtained. The actual dividing method is generally to divide one pixel into two,
Division may be performed for each pixel.

In the divided alignment hybrid liquid crystal cell 41 shifted in the 180 ° tilt direction, the direction at 90 ° with respect to the alignment direction of the liquid crystal layer 39 is excellent in the viewing angle characteristics. Therefore, the viewing angle characteristics are required for the liquid crystal display device. Set it to the direction.

When the alignment film 13b is not divided and aligned, only the reversal is tilted by 20 °, and black and white areas are observed in the alignment direction of the liquid crystal layer 39. The crushed white spot is eliminated.

The response speed of the liquid crystal cell 41 is 1.5 V / 5
With the V switch, off-on was 3 msec, and on-off was 14 msec. Also, in the divided disclination line portion, there is almost no light leakage leading to a decrease in contrast.

According to the liquid crystal display device of the above-described specific example, the minimum drive voltage is higher than 1 V, and
By setting V or more, high-speed response of the liquid crystal layer 39 becomes possible. Note that the liquid crystal layer 39 in the state where the minimum drive voltage is applied by the transparent electrodes 12a and 12b, that is, in the off state (dark state in the case of normally black, white state in the case of normally white), By applying a voltage equal to or higher than a certain threshold so that the liquid crystal molecules 40 whose major axis is substantially horizontal to the plane are made to stand in the vertical direction to the plane,
High response speed can be realized.

The driving voltage applied to the liquid crystal layer 39 of the hybrid alignment is set to 0. By setting the voltage of about several volts to the off minimum voltage, the response speed is slightly increased, but this is insufficient.

In the hybrid alignment liquid crystal display device,
In order to obtain a sufficiently high transmittance, the drive voltage applied to the liquid crystal layer 39 is at the minimum voltage (during normally white display) or at the maximum voltage (during normally black display). ), Liquid crystal layer 39 and biaxial retardation plate 5
2, the total retardation in the in-plane direction is in the range of 0.25 to 0.6 times the wavelength of the light to be used (ideally, 0.5 to 0.6).
Times). Since ordinary liquid crystal display devices use visible light, their total retardation is
It is desirable to set a value within a range of 130 nm to 300 nm. Considering only the transmittance, the optimum value of the total retardation is 275 nm. However, in order to take good values of the chromaticity, the driving voltage, and the response speed, and to increase the transmittance, the total retardation should be 130 nm or more. 300
It is necessary to set an optimal value within the range of nm.

The higher the birefringence Δn of the liquid crystal layer 39, the higher the cell gap dl of the liquid crystal layer 39 while maintaining a sufficiently high transmittance.
c can be reduced and the minimum drive voltage can be increased.
The birefringence Δn of the liquid crystal layer 39 is set so that Δn> 0.15.

The cell gap dlc of the liquid crystal layer 39 is desirably 2.5 μm or more in consideration of the production yield of the liquid crystal display device, but is desirably 5 μm or less to obtain a sufficient response characteristic. 39 cell gap dlc
Was set to 2.5 μm <dlc <5 μm.

Liquid crystal layer 3 of hybrid alignment liquid crystal display device
9, when a driving voltage is applied by the transparent electrodes 12a and 12b, the liquid crystal molecules 4 lying in the horizontal direction of the liquid crystal layer 39
Since 0 does not stand completely in the vertical direction and some retardation remains, an in-plane direction phase difference plate, that is, a biaxial phase difference plate is required. Also, when light obliquely passes through the liquid crystal layer 39 when the liquid crystal molecules 40 stand in the vertical direction, retardation occurs, and it is necessary to compensate for the retardation. Since the liquid crystal layer 39 in the ON state can be regarded as a biaxial retardation plate whose major axis is in the direction normal to the surface, that is, the z-axis direction, the retardation is compensated for. It is preferable to use a biaxial retardation plate having a short axis in the z-axis direction. The refractive index parameter of the compensator has an optimum range that is as opposite as possible to the refractive index anisotropy of the liquid crystal layer 39 in the dark state.

When the thickness of the biaxial retardation plate 52 is d, the optimum range is the birefringence Δn of the liquid crystal layer 39.
And the relationship between the cell gap dlc and the biaxial retardation plate,
Normally when white display, Δn × dlc × 0.02 <( n x -n y) × d <Δn × dl
c × 0.2 Δn × dlc × 0.25 <(n x -n z) × d <Δn × dl
_{c × 1 3 <(n x} -n z) ÷ (n x -n y) becomes, when display of a normally _{black, 150nm <(n x -n y} ) × d <350nm Δn × dlc × 0.1 _{<(n x -n z) ×} d <Δn × dlc
It corresponds to setting to be × 0.5.

In the case of the hybrid alignment liquid crystal display device, since the liquid crystal molecules 40 of the liquid crystal layer 39 rise from one direction, the direction has an asymmetrical viewing angle characteristic, which is lower than when viewed from the front of the liquid crystal display device. The image deteriorates badly, and the phase difference compensator alone is not enough. This problem is solved if the liquid crystal layer 39 is divided into liquid crystal alignment directions different by 180 °.

The dividing method includes a method in which the pretilt direction of the alignment film on the horizontal alignment side or the vertical alignment side is made different by 180 °, and a method in which the pretilt angle is approximately 0 ° on the horizontal alignment side and 0 ° on the vertical alignment side by electric field control. There is a method of making it 90 °. The former method is a mask Rabin method, a UV alignment method, and the like, and the latter method is an electric field control method using an electrode slit. Then, the biaxial retardation plate 52 satisfying the above conditions
By using, it is possible to obtain a hybrid alignment liquid crystal display device having a wide viewing angle.

[0061]

According to the first aspect of the present invention, the liquid crystal molecules are disposed between the first and second transparent substrates facing each other, and the liquid crystal molecules on the first transparent substrate side are disposed on the surface of the first transparent substrate. The liquid crystal layer is oriented substantially perpendicular to the second transparent substrate and the liquid crystal molecules are oriented substantially parallel to the surface of the second transparent substrate. In the transmission type hybrid alignment liquid crystal display device having
Since the minimum drive voltage is set higher than 1 V, a transmissive hybrid alignment liquid crystal display device having a high response speed of the liquid crystal layer can be obtained.

According to a second aspect of the present invention, in the transmission type hybrid alignment liquid crystal display of the first aspect of the present invention, a biaxial retardation plate for optical compensation is provided, and the biaxial retardation plate is provided. The axis in the direction perpendicular to the plate surface is z, the axis with the larger principal refractive index in the axial direction is x, and the smaller axis is y among the two axes parallel to each other in the direction parallel to the plate surface. X
The principal refractive indices in the axis, y-axis, and z-axis directions are _nx ,
_ny and _nz, and the thickness of the biaxial retardation plate is d, the birefringence Δn of the liquid crystal layer and the cell gap dlc
When the relationship between the biaxial retardation plate, when the display of the normally white, Δn × dlc × 0.02 <( n x -n y) × d <Δn × dl
c × 0.2 Δn × dlc × 0.25 <(n x -n z) × d <Δn × dl
c × 1 3 <since (n _x -n _z) ÷ was set to be (n _x -n _y), the response speed of the liquid crystal layer is fast,
Moreover, a transmissive hybrid alignment liquid crystal display device having a wide viewing angle and high contrast can be obtained.

According to the third aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device of the first aspect of the present invention, a biaxial retardation plate for optical compensation is provided, and the biaxial retardation plate is provided. The axis in the direction perpendicular to the plate surface is z, the axis with the larger principal refractive index in the axial direction is x, and the smaller axis is y among the two axes parallel to each other in the direction parallel to the plate surface. X
The principal refractive indices in the axis, y-axis, and z-axis directions are _nx ,
_ny and _nz, and the thickness of the biaxial retardation plate is d, the birefringence Δn of the liquid crystal layer and the cell gap dlc
When the relationship between the biaxial retardation plate, when the display of a normally _{black, 150nm <(n x -n y} ) × d <350nm Δn × dlc × 0.1 <(n x -n z) × d <Δn × dlc
× 0.5, the response speed of the liquid crystal layer is fast,
Moreover, a transmissive hybrid alignment liquid crystal display device having a wide viewing angle and high contrast can be obtained.

According to the fourth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device of the first aspect of the present invention, since the liquid crystal layer is divided into different liquid crystal alignment directions, the response speed of the liquid crystal layer is high, and Thus, a transmissive hybrid alignment liquid crystal display device having a wide viewing angle can be obtained.

According to the fifth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device of the second aspect of the present invention, the liquid crystal layer is divided into different liquid crystal alignment directions, so that the response speed of the liquid crystal layer is high and the contrast is high. And a transmissive hybrid alignment liquid crystal display device having a high viewing angle and a wide viewing angle can be obtained.

According to the sixth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the third aspect of the present invention, since the liquid crystal layer is divided into different liquid crystal alignment directions, the response speed of the liquid crystal layer is high, and the contrast is high. And a transmissive hybrid alignment liquid crystal display device having a high viewing angle and a wide viewing angle can be obtained.

According to the seventh aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the fourth aspect of the present invention, since the liquid crystal layer is divided into liquid crystal alignment directions different by 180 °, the response speed of the liquid crystal layer is high. In addition, a transmissive hybrid alignment liquid crystal display device having a wider viewing angle can be obtained.

According to the eighth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the fifth aspect of the present invention, the liquid crystal layer is divided into liquid crystal alignment directions differing by 180 °.
Since the y-axis direction of the biaxial retardation plate is substantially aligned with the orientation direction substantially horizontal to the surface of the liquid crystal layer, the liquid crystal layer has a high response speed, high contrast, and a wider viewing angle transmission type. A hybrid alignment liquid crystal display device can be obtained.

According to the ninth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the sixth aspect of the present invention, the liquid crystal layer is divided into liquid crystal alignment directions differing by 180 °.
Since the y-axis direction of the biaxial retardation plate is substantially aligned with the orientation direction substantially horizontal to the surface of the liquid crystal layer, the liquid crystal layer has a high response speed, high contrast, and a wider viewing angle transmission type. A hybrid alignment liquid crystal display device can be obtained.

According to the tenth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the second aspect of the present invention, Δn × dlc of the liquid crystal layer and the biaxial retardation plate when the driving voltage is at the minimum voltage. (nx-ny) is 130nm ~ 300n
m, the response speed of the liquid crystal layer is high, the contrast is high, the viewing angle is wide, the chromaticity, the driving voltage, the response speed are good, and the transmittance is high. , A transmissive hybrid alignment liquid crystal display device that can be used.

According to the eleventh aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the third aspect of the present invention, Δn × dlc of the liquid crystal layer and the biaxial retardation plate when the driving voltage is at the maximum voltage. (nx-ny) is 130nm ~ 300n
m, the response speed of the liquid crystal layer is high, the contrast is high, the viewing angle is wide, the chromaticity, the driving voltage, the response speed are good, and the transmittance is high. , A transmissive hybrid alignment liquid crystal display device that can be used.

According to the twelfth aspect of the present invention, in the transmissive hybrid alignment liquid crystal display device of the second aspect of the present invention, the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. Fast response speed, high contrast, wide viewing angle, high transmittance, minimum cell gap dlc, and increase of the minimum drive voltage to increase the response speed under the condition of high response speed. A high transmissive hybrid alignment liquid crystal display device can be obtained.

According to the thirteenth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device of the third aspect of the present invention, the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. Fast response speed, high contrast, wide viewing angle, high transmittance, minimum cell gap dlc, and increase of the minimum drive voltage to increase the response speed under the condition of high response speed. A high transmissive hybrid alignment liquid crystal display device can be obtained.

According to the fourteenth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the second aspect of the present invention, the cell gap dlc of the liquid crystal layer is set in the range of 2.5 μm <dlc <5 μm. Therefore, to obtain a transmissive hybrid alignment liquid crystal display device having a high response speed of the liquid crystal layer, a wide viewing angle, a high contrast, a high production yield of the liquid crystal display device, a high response speed, and a high transmittance. Can be.

According to the fifteenth aspect of the present invention, in the transmission type hybrid alignment liquid crystal display device according to the third aspect of the present invention, the cell gap dlc of the liquid crystal layer is set in the range of 2.5 μm <dlc <5 μm. Therefore, to obtain a transmissive hybrid alignment liquid crystal display device having a high response speed of the liquid crystal layer, a wide viewing angle, a high contrast, a high production yield of the liquid crystal display device, a high response speed, and a high transmittance. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a transmissive hybrid alignment liquid crystal display device according to a specific example of an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a partial configuration of a transmission type hybrid alignment liquid crystal display device according to a specific example of an embodiment of the present invention.

FIG. 3 is a process perspective view showing an alignment processing method of a transmission type hybrid alignment liquid crystal display device according to a specific example of the embodiment of the present invention.

[Explanation of symbols]

11a, 11b transparent substrate, 12a, 12b transparent electrode, 13a, 13b alignment film, 39 liquid crystal layer, 39S
Sealing part, 40 liquid crystal molecules, 42a, 42b polarizing plate, 5
2 Biaxial retardation plate.

Continued on the front page F term (reference) 2H090 HB07Y HC05 HC13 JA15 KA18 MA03 MA12 MB03 2H091 FA50X FA50Z FC23 GA01 GA06 KA01 KA02 KA04 LA19 LA30

Claims (15)

[Claims] A first transparent substrate disposed between the first and second transparent substrates, wherein liquid crystal molecules on the first transparent substrate side are oriented substantially perpendicular to a surface of the first transparent substrate; A transmissive hybrid having a liquid crystal layer in which liquid crystal molecules on the second transparent substrate are oriented substantially parallel to the surface of the second transparent substrate, and a pair of electrodes for applying a driving voltage to the liquid crystal layer; A transmission-type hybrid alignment liquid crystal display device, wherein the minimum drive voltage is set higher than 1 V. 2. The transmissive hybrid alignment liquid crystal display device according to claim 1, further comprising a biaxial retardation plate for optical compensation, wherein the biaxial retardation plate is perpendicular to a plate surface of the biaxial retardation plate. Is the axis of z, of the two axes parallel to each other in the direction parallel to the plate surface, x is the axis with the larger principal refractive index in the axial direction, and y is the axis with the smaller main refractive index.
When the principal refractive indices in the x-axis, y-axis, and z-axis directions are _nx , _ny , and _nz , respectively, and the thickness of the biaxial retardation plate is d, a birefringence [Delta] n and the cell gap dlc layer, the relationship between the biaxial retardation plate, when the display of the normally white, Δn × dlc × 0.02 <( n x -n y) × d <Δn × dl
c × 0.2 Δn × dlc × 0.25 <(n x -n z) × d <Δn × dl
_{c × 1 3 <(n x} -n z) ÷ (n x -n y) and that the set such that the transmission type hybrid alignment liquid crystal display device according to claim. 3. The transmissive hybrid alignment liquid crystal display device according to claim 1, further comprising a biaxial retardation plate for optical compensation, wherein the biaxial retardation plate is perpendicular to the plate surface of the biaxial retardation plate. Is the axis of z, of the two axes parallel to each other in the direction parallel to the plate surface, x is the axis with the larger principal refractive index in the axial direction, and y is the axis with the smaller main refractive index.
When the principal refractive indices in the x-axis, y-axis, and z-axis directions are _nx , _ny , and _nz , respectively, and the thickness of the biaxial retardation plate is d, a birefringence [Delta] n and the cell gap dlc layer, the relationship between the biaxial retardation plate, when the display of a normally _{black, 150nm <(n x -n y} ) × d <350nm Δn × dlc × 0. _{1 <(n x -n z)} × d <Δn × dlc
A transmissive hybrid alignment liquid crystal display device set to be × 0.5. 4. The transmissive hybrid alignment liquid crystal display device according to claim 1, wherein the liquid crystal layer is divided into different liquid crystal alignment directions. 5. The transmissive hybrid alignment liquid crystal display device according to claim 2, wherein the liquid crystal layer is divided into different liquid crystal alignment directions. 6. The transmissive hybrid alignment liquid crystal display device according to claim 3, wherein the liquid crystal layer is divided into different liquid crystal alignment directions. 7. The transmissive hybrid alignment liquid crystal display device according to claim 4, wherein the liquid crystal layer is divided into liquid crystal alignment directions different by 180 °. 8. The transmissive hybrid alignment liquid crystal display device according to claim 5, wherein the liquid crystal layer is divided into liquid crystal alignment directions that are different by 180 °, and the y-axis direction of the biaxial retardation plate is A transmission-type hybrid alignment liquid crystal display device characterized by being substantially aligned with a substantially horizontal alignment direction on the surface of the liquid crystal layer. 9. The transmissive hybrid alignment liquid crystal display device according to claim 6, wherein the liquid crystal layer is divided into liquid crystal alignment directions that are different by 180 °, and the y-axis direction of the biaxial retardation plate is A transmission-type hybrid alignment liquid crystal display device characterized by being substantially aligned with a substantially horizontal alignment direction on the surface of the liquid crystal layer. 10. The transmissive hybrid alignment liquid crystal display device according to claim 2, wherein Δn × dlc and (nx−d) of the liquid crystal layer and the biaxial retardation plate when the driving voltage is the minimum voltage. ny) is set to a value in the range of 130 nm to 300 nm. 11. The transmissive hybrid alignment liquid crystal display device according to claim 3, wherein Δn × dlc and (nx−dlc) of the liquid crystal layer and the biaxial retardation plate when the driving voltage is the maximum voltage. ny) is set to a value in the range of 130 nm to 300 nm. 12. The transmissive hybrid alignment liquid crystal display according to claim 2, wherein the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. apparatus. 13. The transmissive hybrid alignment liquid crystal display according to claim 3, wherein the birefringence Δn of the liquid crystal layer is set to Δn> 0.15. apparatus. 14. The transmissive hybrid alignment liquid crystal display device according to claim 2, wherein a cell gap dlc of the liquid crystal layer is 2.5 μm <dlc <.
A transmissive hybrid alignment liquid crystal display device characterized by being set to a value within a range of 5 μm. 15. The transmissive hybrid alignment liquid crystal display device according to claim 3, wherein a cell gap dlc of the liquid crystal layer is 2.5 μm <dlc <.
A transmissive hybrid alignment liquid crystal display device characterized by being set to a value within a range of 5 μm.