HK1152386B - Liquid crystal display device - Google Patents

Description

Liquid crystal display device having a plurality of pixel electrodes

Technical Field

The present invention relates to a liquid crystal display device, and more particularly to an alignment-division type liquid crystal display device including a vertical alignment type liquid crystal layer.

Background

In recent years, a thin and light liquid crystal display device has been used as a display device used in a display of a personal computer or a display portion of a portable information terminal device. However, conventional TN (Twisted Nematic) or STN (Super Twisted Nematic) liquid crystal display devices have a drawback of narrow viewing angle, and various techniques have been developed to solve this problem.

As a liquid crystal display device having improved viewing angle characteristics, an alignment-division type liquid crystal display device including a vertical alignment type liquid crystal layer is known. Such a liquid crystal display device is called a VA (vertical alignment) mode liquid crystal display device. As one of VA modes, patent document 1 discloses an MVA (Multi-domain Vertical Alignment) mode. In the MVA mode, an alignment regulating structure for regulating the alignment of liquid crystal molecules is provided on each of a pair of substrates facing each other with a liquid crystal layer interposed therebetween. The orientation restriction structure is specifically a projection formed of a dielectric or a slit formed in an electrode. By providing an alignment regulating structure such as a projection or a slit, when a voltage is applied to the liquid crystal layer, a plurality of regions (referred to as "liquid crystal domains") in which the directions in which the liquid crystal molecules are inclined are different from each other are formed, so that the azimuthal angle dependence of the display characteristics is improved, and the viewing angle characteristics are improved.

As described above, in the VA mode liquid crystal display device, high quality display is realized at a wide viewing angle, but recently, as a problem of viewing angle characteristics, a problem of a difference between γ characteristics in front view and γ characteristics in oblique view, that is, a problem of viewing angle dependence of γ characteristics, has newly arisen. The γ characteristic is a gray scale dependency of display luminance. When the γ characteristic is different between the front direction and the oblique direction, the gradation display state is different depending on the observation direction, and thus display with a sense of misregistration is achieved.

As a technique for solving such a problem, patent document 2 discloses a technique for providing a light-shielding layer at a predetermined position in a pixel. The light shielding layer selectively shields light when a liquid crystal domain which causes a sense of misregistration display among the plurality of liquid crystal domains is observed obliquely. Therefore, the display can be prevented from being displayed with a sense of strangeness.

Patent document 1: japanese laid-open patent publication No. 11-242225

Patent document 2: japanese laid-open patent publication No. 2004-93846

Disclosure of Invention

However, when the light-shielding layer disclosed in patent document 2 is provided, there is a problem that the light transmittance in the front direction is lowered. This is because the light-shielding layer provided in the pixel shields a part of the pixel also in a front view. In order to sufficiently suppress the occurrence of the display misregistration, it is necessary to increase the width of the light-shielding layer to a certain extent or more, and therefore, it is inevitable that the light transmittance in the front direction is reduced to a certain extent.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an alignment-division type liquid crystal display device including a vertical alignment type liquid crystal layer, which can realize display without a sense of misregistration while suppressing a decrease in light transmittance.

The liquid crystal display device of the invention comprises a first substrate; a second substrate; and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate, and having a plurality of pixels each including: a first electrode provided on the first substrate on the liquid crystal layer side; a second electrode provided on the liquid crystal layer side of the second substrate; and the liquid crystal layer located between the first electrode and the second electrode, wherein the liquid crystal layer in each of the plurality of pixels has a plurality of liquid crystal regions having different liquid crystal molecule inclination orientations when a voltage is applied between the first electrode and the second electrode, each of the plurality of pixels has a light shielding portion disposed at a boundary of the plurality of liquid crystal regions, the light shielding portion is provided on at least one of the first substrate and the second substrate such that, when a voltage is applied between the first electrode and the second electrode, the liquid crystal molecules in the vicinity of the boundary are inclined such that an end portion on a substrate side where the light shielding portion is provided is distant from the boundary, and the light shielding portion includes: a first light-shielding layer; and a second light-shielding layer which overlaps with the first light-shielding layer with a predetermined gap therebetween.

Alternatively, the liquid crystal display device of the present invention includes a first substrate; a second substrate; and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate, and having a plurality of pixels each including: a first electrode provided on the first substrate on the liquid crystal layer side; a second electrode provided on the liquid crystal layer side of the second substrate; and the liquid crystal layer located between the first electrode and the second electrode, wherein the liquid crystal layer in each of the plurality of pixels has a plurality of liquid crystal regions having different liquid crystal molecule inclination orientations when a voltage is applied between the first electrode and the second electrode, and the plurality of liquid crystal regions include: a first liquid crystal region in which a retardation value of light incident on the liquid crystal layer from a direction inclined with respect to a normal direction of a display surface increases with an increase in applied voltage; and a second liquid crystal region in which a value of the retardation temporarily decreases with an increase in an applied voltage and then increases, each of the plurality of pixels having a light shielding portion that is provided on at least one of the first substrate and the second substrate and that selectively shields the first liquid crystal region from light when viewed from a direction inclined with respect to a normal direction of a display surface, the light shielding portion including: a first light-shielding layer; and a second light-shielding layer which overlaps with the first light-shielding layer with a predetermined gap therebetween.

In a preferred embodiment, the liquid crystal display device of the present invention further includes a pair of polarizing plates disposed in a crossed nicol arrangement, and the orientation in which the liquid crystal molecules are inclined in each of the plurality of liquid crystal regions forms an angle of approximately 45 ° with the polarizing axes of the pair of polarizing plates.

In a preferred embodiment, the plurality of liquid crystal regions include 4 liquid crystal regions in which liquid crystal molecules are tilted in a first azimuth, a second azimuth, a third azimuth, and a fourth azimuth, a difference in any 2 azimuths among the first azimuth, the second azimuth, the third azimuth, and the fourth azimuth is substantially equal to an integral multiple of 90 °, and in any 2 liquid crystal regions adjacent to each other among the 4 liquid crystal regions, azimuths in which liquid crystal molecules are tilted are substantially different by 90 °.

In a preferred embodiment, the first electrode includes: a cross-shaped main portion arranged to overlap with the polarization axes of the pair of polarizing plates; and a plurality of branch portions extending in a direction of substantially 45 ° from the trunk portion, wherein the light shielding portion is provided on the first substrate.

In a preferred embodiment, the liquid crystal display device of the present invention further includes: a pair of vertical alignment films provided between the first electrode and the liquid crystal layer and between the second electrode and the liquid crystal layer; and an alignment maintaining layer made of a photopolymer formed on each of the surfaces of the pair of vertical alignment films on the liquid crystal layer side, and defining a pretilt azimuth of alignment molecules of the liquid crystal layer when no voltage is applied to the liquid crystal layer.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, in an alignment-division liquid crystal display device including a vertical alignment type liquid crystal layer, it is possible to realize display without a sense of misregistration while suppressing a decrease in light transmittance.

Drawings

Fig. 1 is a diagram schematically showing a liquid crystal display device 100 according to a preferred embodiment of the present invention, and is a plan view showing a region corresponding to 1 pixel.

Fig. 2 is a cross-sectional view taken along line 2A-2A' in fig. 1, where (a) shows a state where no voltage is applied to the liquid crystal layer, and (b) shows a state where a predetermined voltage is applied to the liquid crystal layer.

Fig. 3 is a plan view showing a structure of a pixel electrode provided in the liquid crystal display device 100.

Fig. 4 is a cross-sectional view schematically showing a liquid crystal display device 500 without a light shielding portion at the boundary between a plurality of liquid crystal regions.

Fig. 5 is a graph showing the voltage-transmittance characteristic when the liquid crystal display device 500 is viewed from the front direction and the voltage-transmittance characteristic when viewed from the oblique direction.

Fig. 6 is a graph showing voltage-transmittance characteristics when a liquid crystal region in which liquid crystal molecules are tilted so as to fall to the observer side is observed from a tilt direction, and voltage-transmittance characteristics when a liquid crystal region in which liquid crystal molecules are tilted so as to fall to the opposite side of the observer is observed from a tilt direction.

Fig. 7 schematically shows a region shielded from light by the light shielding portion when the liquid crystal display device 100 is viewed from the front direction.

Fig. 8(a) and (b) schematically show a region shielded from light by the light shielding portion when the liquid crystal display device 100 is viewed from an oblique direction.

Fig. 9 schematically shows a region shielded from light by a light shielding portion having a single-layer structure when the liquid crystal display device 600 provided with the light shielding portion is viewed from an oblique direction.

Fig. 10 shows a simulation result of a transmittance distribution (transmittance distribution in front view) in a pixel in a white display state, where (a) corresponds to the liquid crystal display device 500, (b) corresponds to the liquid crystal display device 600, and (c) corresponds to the liquid crystal display device 100.

Fig. 11 is a diagram showing a simulation result of a transmittance distribution (transmittance distribution in oblique observation) of a pixel in a white display state, where (a) corresponds to the liquid crystal display device 500, (b) corresponds to the liquid crystal display device 600, and (c) corresponds to the liquid crystal display device 100.

Fig. 12 is a graph showing the light transmittance in the front direction for (1) the case where no light-shielding portion is provided, (2) the case where a light-shielding portion of a single-layer structure having a light-shielding layer with a width of 1.5 μm is provided, (3) the case where a light-shielding portion of a single-layer structure having a light-shielding layer with a width of 3.0 μm is provided, and (4) the case where a light-shielding portion of a multi-layer (2-layer) structure having a light-shielding layer with a width of 1.5 μm is provided.

Fig. 13(a) to (d) show simulation results of transmittance distributions (transmittance distributions in front view) in pixels in a white display state for each of the above cases (1) to (4).

Fig. 14 is a graph showing the gray scale dependency of the normalized luminance for the front direction and the 45 ° viewing angle direction.

Fig. 15 is a cross-sectional view schematically showing another liquid crystal display device 100A according to a preferred embodiment of the present invention, in which (a) shows a state where no voltage is applied to the liquid crystal layer, and (b) shows a state where a predetermined voltage is applied to the liquid crystal layer.

Fig. 16(a) and (b) schematically show a region shielded from light by the light shielding portion when the liquid crystal display device 100A is viewed from an oblique direction.

Fig. 17 is a cross-sectional view schematically showing still another liquid crystal display device 100B according to a preferred embodiment of the present invention.

Description of reference numerals

11. 21: transparent substrate

12: pixel electrode

12 a: trunk part

12 b: branching part

13. 23: vertical alignment film

14. 24: orientation maintaining layer

15: interlayer insulating film

16. 26: polarizing plate

17. 27: light shielding part

17a, 27 a: a first light-shielding layer

17b, 27 b: a second light-shielding layer

22: counter electrode

30: liquid crystal layer

30 a: liquid crystal molecules

100 a: active matrix substrate (TFT substrate)

100 b: opposed substrate (color filter substrate)

100. 100A, 100B: liquid crystal display device having a plurality of pixel electrodes

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, an active matrix type liquid crystal display device including a Thin Film Transistor (TFT) will be described as an example, but the present invention is not limited thereto.

Fig. 1 and 2 show a liquid crystal display device 100 according to the present embodiment. Fig. 1 is a plan view of a region corresponding to 1 pixel of the liquid crystal display device 100 viewed from the normal direction of the display surface, and fig. 2(a) and (b) are cross-sectional views taken along the line 2A-2A' in fig. 1. Fig. 2(a) shows a state where no voltage is applied to the liquid crystal layer 30, and fig. 2(b) shows a state where a predetermined voltage is applied to the liquid crystal layer 30.

As shown in fig. 2a and b, the liquid crystal display device 100 includes an active matrix substrate (hereinafter, referred to as a "TFT substrate") 100a, a counter substrate (also referred to as a "color filter substrate") 100b, and a vertical alignment type liquid crystal layer 30 provided between the TFT substrate 100a and the counter substrate 100 b.

In addition, the liquid crystal display device 100 has a plurality of pixels. Each pixel includes: a pixel electrode 12 provided on the liquid crystal layer 30 side of the TFT substrate 100 a; a counter electrode 22 provided on the liquid crystal layer 30 side of the counter substrate 100 b; and a liquid crystal layer 30 positioned between the pixel electrode 12 and the counter electrode 22. The pixel electrode 12 is formed on a transparent substrate (e.g., a glass substrate) 11 with an interlayer insulating film 15 interposed therebetween, and has a fine stripe pattern as described later in detail. The counter electrode 22 is formed on a transparent substrate (e.g., a glass substrate) 21. Although not shown here, a color filter is provided between the transparent substrate 21 and the counter electrode 22.

A pair of vertical alignment films 13 and 23 are provided between the pixel electrode 12 and the liquid crystal layer 30 and between the counter electrode 22 and the liquid crystal layer 30. Further, on the respective surfaces of the vertical alignment films 13 and 23 on the liquid crystal layer 30 side, alignment sustaining layers 14 and 24 composed of a photopolymer are formed.

The alignment sustaining layers 14 and 24 are formed by polymerizing a photopolymerizable compound (typically, a photopolymerizable monomer) mixed in advance in a liquid crystal material in a state where a voltage is applied to the liquid crystal layer 30 after the liquid crystal cell is formed. The liquid crystal molecules 30a (having negative dielectric anisotropy) contained in the liquid crystal layer 30 are aligned and restricted by the vertical alignment films 13 and 23 until the photopolymerizable compound is polymerized. When a sufficiently high voltage (for example, a white display voltage) is applied to the liquid crystal layer 30, the liquid crystal molecules 30a are tilted in a predetermined direction by an oblique electric field generated at the edge portion of the fine stripe pattern of the pixel electrode 12. The alignment sustaining layers 14 and 24 function to sustain (store) the alignment of the liquid crystal molecules 30a in a state where a voltage is applied to the liquid crystal layer 30 even after the voltage is removed (in a state where no voltage is applied). Therefore, the pretilt azimuths of the liquid crystal molecules 30a (azimuths in which the liquid crystal molecules 30a tilt when no voltage is applied) defined by the alignment sustaining layers 14 and 24 coincide with the azimuths in which the liquid crystal molecules 30a tilt when a voltage is applied.

A pair of polarizing plates 16 and 26 are provided on the TFT substrate 100a and the counter substrate 100b on the opposite side to the liquid crystal layer 30. The polarizers 16 and 26 are orthogonally nicol configured. That is, the polarizing plates 16 and 26 are arranged such that the respective polarizing axes are orthogonal to each other.

As shown in fig. 1, the pixel electrode 12 has a fine stripe pattern, and thus each pixel of the liquid crystal display device 100 is divided into alignment. That is, the liquid crystal layer 30 has a plurality of liquid crystal regions R having different azimuths in which the liquid crystal molecules 30a tilt when a voltage is applied. As will be described in detail later, the light shielding portion 17 is disposed at the boundary between the plurality of liquid crystal regions R. Hereinafter, a more specific structure of the pixel electrode 12 and a relationship between the orientations of the liquid crystal molecules 30a in the plurality of liquid crystal regions R will be described with reference to fig. 3.

As shown in fig. 3, the pixel electrode 12 includes: a cross-shaped main portion 12a arranged so as to overlap the polarizing axes of the pair of polarizing plates 16 and 26; and a plurality of branch portions 12b extending from the trunk portion 12a in a direction of substantially 45 °. Here, since one polarizing axis of the polarizing plates 16 and 26 is arranged in the horizontal direction and the other polarizing axis is arranged in the vertical direction, the trunk portion 12a has a cross shape in which the straight line portions 12a1 extending in the horizontal direction and the straight line portions 12a2 extending in the vertical direction intersect each other near the center. The pixel electrode 12 having such a fine stripe pattern is disclosed in, for example, japanese patent laid-open nos. 2003-149647 and 2006-78968. Such a pattern is sometimes called a fish bone shape.

The plurality of branch portions 12b are divided into 4 groups corresponding to 4 regions divided by the cross-shaped trunk portion 12 a. When the display surface is compared with the pointer dial of the timepiece, the plurality of branch portions 12b are divided into: a first group of branch portions 12b1 extending in the direction of azimuth angle 45 °; a second group of branch portions 12b2 extending in the direction of azimuth angle 135 °; a third group consisting of branch portions 12b3 extending in the direction of azimuth angle 225 °; and a fourth group of branch portions 12b4 extending in the direction of azimuth angle 315 deg..

Each width L of the plurality of branch portions 12b and the interval S of adjacent branch portions 12b in each of the first group, the second group, the third group, and the fourth group are typically 1.5 μm or more and 5.0 μm or less. From the viewpoint of stability of the alignment of the liquid crystal molecules 30a and luminance, the width L and the interval S of the branch portion 12b are preferably within the above ranges.

The oblique electric field generated between the adjacent branch portions 12b (i.e., the portion where the conductive film of the pixel electrode 12 is not present) defines the orientation in which the liquid crystal molecules 30a are tilted (the azimuthal angle component of the long axis of the liquid crystal molecules 30a after being tilted by the electric field). This orientation is a direction parallel to the branch portions 12b arranged in a stripe pattern and toward the trunk portion 12 a. Specifically, the azimuth of the tilt azimuth (first azimuth: arrow a) defined by branch portion 12B1 of the first group is about 225 °, the azimuth of the tilt azimuth (second azimuth: arrow B) defined by branch portion 12B2 of the second group is about 315 °, the azimuth of the tilt azimuth (third azimuth: arrow C) defined by branch portion 12B3 of the third group is about 45 °, and the azimuth of the tilt azimuth (fourth azimuth: arrow D) defined by branch portion 12B4 of the fourth group is about 135 °.

As described above, the liquid crystal layer 30 of each pixel has 4 liquid crystal regions R having different azimuths in which the liquid crystal molecules 30a tilt when a voltage is applied. In each liquid crystal region R, the azimuths a to D in which the liquid crystal molecules 30a are inclined make an angle of approximately 45 ° with the polarizing axes of the pair of polarizing plates 16 and 26. In addition, the difference in any 2 azimuths a to D is substantially equal to an integral multiple of 90 °, and the azimuths in which the liquid crystal molecules 30a tilt in any 2 liquid crystal regions R adjacent to each other out of the 4 liquid crystal regions R are substantially different by 90 °.

Each of the 4 liquid crystal regions R when a voltage is applied may be referred to as a "liquid crystal domain". The 4 azimuths a to D are azimuths of directors of 4 liquid crystal domains formed when a voltage is applied. The director orientation of the liquid crystal domain makes an angle of approximately 45 ° with the polarizing axis of the pair of polarizing plates 16 and 26, and is more preferable in that retardation by the liquid crystal molecules 30a is effectively utilized to realize bright display. A structure in which 4 liquid crystal domains are formed in 1 pixel is referred to as a 4-division alignment structure or simply a 4D structure. In addition, an example in which 1 4D configurations are formed in 1 pixel is shown here, but if a plurality of the above-described electrode configurations are formed in 1 pixel, a plurality of 4D configurations can be formed in 1 pixel.

The liquid crystal display device 100 also has alignment sustaining layers 14 and 24, and these alignment sustaining layers 14 and 24 function to define the pretilt azimuths of the liquid crystal layer 30a of the 4 liquid crystal regions R when no voltage is applied to the liquid crystal layer 30. The pretilt azimuth coincides with azimuths a to D of directors of the respective liquid crystal domains of the 4D structure that can be obtained by the above-described electrode structure. By providing such orientation maintaining layers 14 and 24, the stability of orientation and response characteristics are improved.

The orientation maintaining layers 14 and 24 are formed using a technique called "Polymer stabilized alignment technology" (sometimes referred to as "PSA technique"). Specific methods for producing the orientation maintaining layers 14 and 24 by the PSA technique are disclosed in japanese patent laid-open nos. 2002-357830, 2003-149647, 2006-78968, and the like.

Next, the structure of the liquid crystal display device 100 will be described with reference to fig. 1 and 2 again. In the liquid crystal display device 100 of the present embodiment, each pixel has the light shielding portion 17 disposed at the boundary of the plurality of liquid crystal regions R. Here, since the trunk portion 12a of the pixel electrode 12 is located at the boundary of the liquid crystal region R, the light shielding portion 17 is provided at a position corresponding to the trunk portion 12a of the pixel electrode 12.

As shown in fig. 2, the light shielding portion 17 is provided on the TFT substrate 100 a. When a voltage is applied between the pixel electrode 12 and the counter electrode 22, the liquid crystal molecules 30a near the boundary of the plurality of liquid crystal regions R are inclined so that the end on the substrate side where the light shielding portion 17 is provided (i.e., the TFT substrate 100a) is away from the boundary, as can be seen from fig. 2 (b).

Further, the light shielding portion 17 includes: the first light-shielding layer 17 a; and a second light-shielding layer 17b that overlaps the first light-shielding layer 17a with a predetermined gap G therebetween. That is, the light shielding portion 17 is constituted by a plurality of light shielding layers 17a and 17b which overlap each other when viewed from the display surface normal direction. In addition, in fig. 2(a) and (b), a case where the width Wa of the first light shielding layer 17a and the width Wb of the second light shielding layer 17b are equal to each other and smaller than the width of the trunk portion 12a of the pixel electrode 12 is illustrated, but the present invention is not limited to such a structure. The width Wa of the first light-shielding layer 17a and the width Wb of the second light-shielding layer 17b may be different from each other, and may be equal to or greater than the width of the main portion 12a of the pixel electrode 12.

Since the liquid crystal display device 100 has the light-shielding portion 17 as described above, the difference in display characteristics between when viewed from the front direction and when viewed from an oblique direction is small, and display without a sense of misregistration is possible. The reason for this will be described below.

First, the reason why the display is perceived as being out of alignment in the conventional liquid crystal display device without the light shielding portion as described above will be described. Fig. 4 shows a liquid crystal display device 500 without a light shielding portion at the boundary of a plurality of liquid crystal regions R. The liquid crystal display device 500 has substantially the same structure as the liquid crystal display device 100 except that there is no light shielding portion.

In the liquid crystal display device 500, each pixel is also divided into a plurality of liquid crystal regions R, and therefore the azimuthal dependence of the display characteristics is improved. However, in the liquid crystal display device 500, a large difference occurs between the display characteristics when viewed from the front direction and the display characteristics when viewed from the oblique direction.

Fig. 5 shows, in a standardized manner, the voltage-transmittance characteristic when the liquid crystal display device 500 is observed from the front direction (the direction indicated by the arrow V1 in fig. 4) and the voltage-transmittance characteristic when the liquid crystal display device 500 is observed from the oblique direction (the direction indicated by the arrow V2 in fig. 4) in which the viewing angle is tilted along the polarization axis. Fig. 5 is a graph in which the horizontal axis represents the applied voltage (V) to the liquid crystal layer 30, and the vertical axis represents the normalized transmittance.

As shown in fig. 5, the voltage-transmittance curve L2 when viewed from the oblique direction is steeper than the voltage-transmittance curve L1 when viewed from the front direction, and the transmittance when viewed from the oblique direction is higher than the transmittance when viewed from the front direction in a state where a voltage of an intermediate gray level is applied.

The reason why the transmittance in the oblique direction becomes high at the intermediate gray scale voltage is the operation of the liquid crystal molecules 30a of the specific liquid crystal region R among the plurality of liquid crystal regions R existing in the pixel. Specifically, this is due to the operation of the liquid crystal molecules 30a that are tilted toward the side opposite to the observer when viewed from the oblique direction (i.e., tilted so that the end portion on the counter substrate 100b side is away from the observer).

Here, attention is paid to 2 liquid crystal regions R shown in fig. 4. For example, when the 2 liquid crystal regions R are observed from a direction in which the viewing angle is tilted along the polarization axis (the direction indicated by the arrow V2 in fig. 4), the liquid crystal molecules 30a of the 2 liquid crystal regions are all tilted to an azimuth of an angle of 45 ° to the polarization axis, the liquid crystal molecules 30a of the left liquid crystal region R are tilted to the viewer side, and the liquid crystal molecules 30a of the right liquid crystal region R are tilted to the opposite side to the viewer side.

Fig. 6 shows the voltage-transmittance characteristics when the 2 liquid crystal regions R shown in fig. 4 are observed from an oblique direction. Fig. 6 is a graph showing a voltage-transmittance characteristic L3 in the liquid crystal region R (the liquid crystal region R shown on the left side in fig. 4) in which the liquid crystal molecules 30a are tilted so as to fall to the observer side, and a voltage-transmittance curve L4 in the liquid crystal region R (the liquid crystal region R shown on the right side in fig. 4) in which the liquid crystal molecules 30a are tilted so as to fall to the opposite side to the observer side.

As shown in fig. 6, in the liquid crystal region R where the liquid crystal molecules 30a fall toward the observer side, the transmittance temporarily decreases with an increase in voltage and then increases (curve L3). In contrast, in the liquid crystal region R where the liquid crystal molecules 30a fall to the side opposite to the observer, the transmittance increases almost monotonously with the increase in voltage (curve L4). This is because the retardation of the liquid crystal layer 30 with respect to light entering the liquid crystal layer 30 obliquely (i.e., from a direction oblique to the normal direction of the display surface) temporarily decreases and then increases with an increase in voltage in the liquid crystal region R where the liquid crystal molecules 30a fall toward the observer side, and monotonically increases with an increase in voltage in the liquid crystal region R where the liquid crystal molecules 30a fall toward the opposite side of the observer.

The voltage-transmittance characteristics when viewed from an oblique direction shown in fig. 5 are characteristics obtained by adding the voltage-transmittance characteristics of the respective liquid crystal regions R shown in fig. 6. Therefore, it is considered that the increase in transmittance when viewed from an oblique direction at the intermediate gray scale voltage is caused by the liquid crystal molecules 30a falling to the side opposite to the observer.

In the liquid crystal display device 100 of the present embodiment, the light shielding portion 17 is arranged in advance at the boundary between the plurality of liquid crystal regions R, and the light shielding portion 17 is provided on at least one substrate (here, the TFT substrate 100a) such that the liquid crystal molecules 30a in the vicinity of the boundary are inclined such that the end portion on the substrate side where the light shielding portion 17 is provided is away from the boundary when a voltage is applied.

The light shielding portion 17 thus provided selectively shields, when viewed from an oblique direction (a direction inclined with respect to the normal direction of the display surface), a liquid crystal region R in which the liquid crystal molecules 30a in 2 liquid crystal regions R adjacent to each other fall toward the side opposite to the observer, that is, a liquid crystal region R in which the retardation value with respect to light in the oblique direction increases almost monotonically with an increase in voltage.

Fig. 7 and 8 schematically show a region shielded from light by the light shielding portion 17 when the liquid crystal display device 100 is viewed from the front direction V1 and the oblique directions V2 and V3.

As shown in fig. 7, the light shielding portion 17 shields the liquid crystal layer 30 directly above it when viewed from the front direction V1. Therefore, the ratio of the contribution to the respective displays of the 2 liquid crystal regions R does not change.

On the other hand, as shown in fig. 8(a), when viewed from the oblique direction V2, the light shielding portion 17 selectively shields the liquid crystal region R where the liquid crystal molecules 30a fall to the side opposite to the observer (i.e., the right side liquid crystal region R) because of the occurrence of parallax. As shown in fig. 8(b), the light shielding portion 17 selectively shields the liquid crystal region R on the side opposite to the observer (i.e., the left liquid crystal region R) from light when viewed from the opposite oblique direction V3. Therefore, a part of the liquid crystal region R where the liquid crystal molecules 30a fall to the side opposite to the observer does not contribute to display when viewed from an oblique direction. Therefore, the voltage-transmittance characteristic when viewed from an oblique direction can be made closer to the voltage-transmittance characteristic when viewed from the front direction by suppressing an increase in transmittance of the halftone voltage. As a result, the display characteristics when viewed from the oblique direction and the display characteristics when viewed from the front direction can be made close to each other, and display without a sense of misregistration can be realized.

In addition, the light shielding portion 17 of the liquid crystal display device 100 in the present embodiment includes: the first light-shielding layer 17 a; and a second light-shielding layer 17b that overlaps the first light-shielding layer 17a with a predetermined gap G therebetween. By providing the light shielding portion 17 having such a multilayer structure, it is possible to suppress a decrease in light transmittance in the front direction as compared with the case where a light shielding portion having a single-layer structure as disclosed in patent document 2 is provided.

Fig. 9 shows an example of a liquid crystal display device provided with a light shielding portion having a single-layer structure. The liquid crystal display device 600 shown in fig. 9 has substantially the same configuration as the liquid crystal display device 100 shown in fig. 2, except that the light shielding portion 17' is formed of a single light shielding layer 17 c. The light shielding portion 17' of the liquid crystal display device 600 can selectively shield the liquid crystal region R in which the liquid crystal molecules 30a are tilted to the side opposite to the observer even when viewed from the tilt direction V2 (or the tilt direction V3), and thus can realize display without a sense of misregistration. However, when light is blocked in a region of the same size, as can be seen from a comparison between fig. 8(a) and fig. 9, in the light blocking portion 17' having a single-layer structure, the width Wc of the light blocking layer 17c needs to be larger than that of the light blocking portion 17 having a multi-layer structure.

In contrast, in the liquid crystal display device 100 of the present embodiment, the widths (widths Wa and Wb in fig. 2 a) of the first light-shielding layer 17a and the second light-shielding layer 17b required to sufficiently obtain the effect of preventing the occurrence of the sense of misregistration can be reduced. The first light-shielding layer 17a and the second light-shielding layer 17b provided with a predetermined gap G therebetween along the normal direction of the slope can shield different regions (of course, may partially overlap) when viewed in the oblique direction. Therefore, a decrease in light transmittance in the front direction can be suppressed, and bright display can be realized. Hereinafter, the effect of suppressing the decrease in light transmittance by the light shielding portion 17 having a multilayer structure will be described more specifically.

Fig. 10 and 11 show simulation results of transmittance distributions in pixels in a white display state for a liquid crystal display device 500 without a light shielding portion, a liquid crystal display device 600 with a single-layer-structured light shielding portion 17', and a liquid crystal display device 100 with a multilayer (2-layer) -structured light shielding portion 17. Fig. 10(a), (b) and (c) show transmittance distributions when viewed from the front, and fig. 11(a), (b) and (c) show transmittance distributions when viewed obliquely (specifically, when the azimuth angle is 0 °, that is, the viewing angle is tilted in the 3-point direction).

The pixels used in the simulation were pixels with a pixel pitch of 25.5 μm × 76.5 μm, corresponding to VGA class type 2-3. Regarding the fishbone pattern of the pixel electrode 12, the thickness of the trunk portion 12a (the width of the straight portion 12a1 extending in the horizontal direction and the straight portion 12a2 extending in the vertical direction) was set to 2.5 μm, the number of branch portions 12b in each region corresponding to 4 liquid crystal domains was set to 4, and the width L and the interval S of the branch portions 12b were set to 2.5 μm, respectively. Further, the widths of the light-shielding layers 17a, 17b, and 17c are all 1.5 μm.

In the liquid crystal display device 500 without the light shielding portion, 4 liquid crystal domains are in a substantially uniform white display state when viewed from the front, and the boundaries between these liquid crystal domains are clearly observed as cross-shaped dark lines parallel to the absorption axis of the polarizing plate, which are arranged orthogonally to nicol, as shown in fig. 10 (a). Therefore, the 4D structure is clearly formed, and almost all of the liquid crystal molecules 30a in each liquid crystal domain are aligned to the azimuth of a predetermined director (the azimuth of 45 ° with respect to the polarizing axis of the polarizing plate). In the liquid crystal display device 500, no light-shielding portion is provided at the boundary between the liquid crystal domains, and therefore, no specific liquid crystal domain is not shielded from light when viewed obliquely, and the areas of the regions that each liquid crystal domain contributes to display are the same as shown in fig. 11 (a).

In contrast, in the liquid crystal display device 600 provided with the light shielding portion 17 'having a single-layer structure and the liquid crystal display device 100 provided with the light shielding portion 17 having a multi-layer structure, as shown in fig. 10(b) and 10(c), respectively, the boundaries between the liquid crystal domains are shielded from light by the light shielding portions 17' and 17 when viewed from the front. On the other hand, in oblique observation, as shown in fig. 11(b) and 11(c), the light shielding portions 17' and 17 selectively shield 2 liquid crystal domains on the right side out of the 4 liquid crystal domains. However, as can be seen from comparison of fig. 11(b) with fig. 11(c), the light shielding portion 17 of the multilayer structure shields light in a region larger than the light shielding portion 17' of the single-layer structure.

Thus, if the light-shielding layer has the same width, the light-shielding portion 17 of the multilayer structure can shield light in a larger area than the light-shielding portion 17' of the single-layer structure. Therefore, when the same size region is shielded from light as viewed from an oblique direction, the widths Wa and Wb of the light shielding layers 17a and 17b constituting the light shielding portion 17 of the multilayer structure are smaller than the width Wc of the light shielding layer 17c constituting the light shielding portion 17' of the single-layer structure. Therefore, in the liquid crystal display device 100 according to the present embodiment, it is possible to realize display without a sense of misregistration while suppressing a decrease in light transmittance.

In fig. 12, (1) the case where no light shielding portion is provided, (2) the case where a light shielding portion 17 'having a single-layer structure of a light shielding layer 17c with a width of 1.5 μm is provided, (3) the case where a light shielding portion 17' having a single-layer structure of a light shielding layer 17c with a width of 3.0 μm is provided, and (4) the case where a light shielding layer 17 having a multi-layer (2-layer) structure of light shielding layers 17a and 17b with a width of 1.5 μm is provided, indicate the light transmittance in the front direction. In fig. 13(a) to (d), the light transmittance distribution (when viewed from the front) of the pixel in the white display state is shown for each of the above-described cases (1) to (4).

As can be seen from fig. 13(a), the boundaries of the plurality of liquid crystal regions R are originally regions that are visually recognized as dark lines, and are regions that contribute little to display. Therefore, as can be seen from fig. 12, 13(b) and (d), in the cases (2) and (4) where the width of the light-shielding layer is narrow, the light transmittance is hardly decreased. On the other hand, as can be seen from fig. 12 and 13(c), in the case of the wide light shielding layer (3), the light transmittance is greatly reduced.

Fig. 14 shows the front direction and the 45 ° viewing angle direction (the inclination angle from the normal of the display surface is 45 °, and the azimuth angle is 0 °), and shows the gray scale dependency of the normalized luminance. Here, the normalized luminance is a value obtained by normalizing the luminance in each direction, with the luminance when the white voltage (highest grayscale voltage) in each direction is applied being 1. As can be seen from fig. 14, the curve showing the normalized luminance in the front direction is different from the curve showing the normalized luminance in the 45 ° viewing angle direction. This indicates that the displayed γ characteristic differs in the front direction and the oblique direction. Among them, it is known that the cases (2) and (4) in which the light shielding portion is provided suppress an increase in luminance in the middle gray scale compared with the case (1) in which the light shielding portion is not provided. In addition, it is known that, although the width of the light shielding layer is the same, (4) the case where the light shielding portion 17 of the multilayer structure is provided further suppresses an increase in luminance compared to (2) the case where the light shielding portion 17' of the single-layer structure is provided. Although not shown in fig. 14, if the width of the light-shielding layer is increased as in the case of (3), the viewing angle characteristics similar to those in the case of (4) can be obtained. However, in this case, the light transmittance in the front direction is greatly reduced.

As described above, in the liquid crystal display device 100 according to the present embodiment, the light shielding portion 17 having a multilayer structure is provided at the boundary between the plurality of liquid crystal regions R, whereby display without a sense of misregistration can be realized while suppressing a decrease in light transmittance. The arrangement, width, shape, and the like of the first light-shielding layer 17a and the second light-shielding layer 17b constituting the light-shielding portion 17 are not limited to those exemplified in the present embodiment, and may be appropriately set according to the method of the liquid crystal display device, the desired light transmittance, display characteristics, and the like.

For example, fig. 2 shows the first light-shielding layer 17a formed on the transparent substrate 11 and the second light-shielding layer 17b formed on the pixel electrode 12, and the first light-shielding layer 17a and the second light-shielding layer 17b may be provided in any layer in the stacked structure of the TFT substrate 100a as long as they are arranged so as to overlap each other with a predetermined gap G therebetween when viewed from the display surface normal direction. For example, the second light-shielding layer 17b may be provided under the pixel electrode 12 instead of on the pixel electrode 12.

The first light-shielding layer 17a and the second light-shielding layer 17b are formed using a light-shielding material such as a metal such as aluminum or a resin containing a pigment. The first light-shielding layer 17a and the second light-shielding layer 17b may be formed at any stage of the process of manufacturing the TFT substrate 100 a. When the first light-shielding layer 17a or the second light-shielding layer 17b is formed using the same opaque components (for example, scanning lines or signal lines) originally included in the TFT substrate 100a, a new step for forming the first light-shielding layer 17a or the second light-shielding layer 17b is not required.

The light shielding portion 17 does not necessarily have to have a 2-layer structure. For example, the light shielding portion 17 may have a 3-layer structure including a third light shielding layer in addition to the first light shielding layer 17a and the second light shielding layer 17 b.

The widths Wa and Wb of the first light-shielding layer 17a and the second light-shielding layer 17b or the gap G therebetween may be set so as to effectively shield the liquid crystal region R from light, depending on the thickness of the liquid crystal layer 30, the size of the liquid crystal region R, and the like. The widths Wa and Wb of the first light-shielding layer 17a and the second light-shielding layer 17b preferably do not exceed the width of the boundary between the liquid crystal domains (the region observed as a dark line in the white display state) too much from the viewpoint of suppressing the decrease in transmittance in the front direction. Specifically, the widths Wa and Wb are preferably set so that the decrease in the light transmittance in the front direction becomes 10% or less, more specifically 3 μm or less, when compared with the case where the light shielding portion 17 is not provided.

In the present embodiment, the configuration in which the 4D structure is formed from the fishbone-shaped pixel electrode 12 is illustrated, but the present invention is not limited thereto. As a method of performing the orientation division, various well-known methods can be used. For example, alignment division may be performed by various alignment regulating structures (such as slits or projections as disclosed in patent document 1) used in a general MVA mode.

Further, alignment division may be performed by photo-alignment treatment (photo-alignment method). The photo-alignment treatment is disclosed in, for example, Japanese patent laid-open publication No. Hei 2-277025 or Japanese patent laid-open publication No. Hei 4-303827. The photo-alignment treatment is a technique of irradiating polarized ultraviolet light on an alignment film formed of a compound having a light-reflective functional group to cause anisotropic chemical reaction of molecules in the alignment film, thereby finding an alignment regulating force. Recently, a method of irradiating not polarized ultraviolet light but unpolarized ultraviolet light is also being developed. The alignment film to which an alignment regulating force is applied by the photo-alignment treatment is also referred to as a "photo-alignment film". Alternatively, the orientation division may be performed according to the nanostructure pattern. The nanostructure pattern is formed by a so-called nano-friction method using AFM (atomic force microscope), for example.

As described above, various methods can be used as the alignment division method, and therefore the shape of the boundary between the liquid crystal domains formed when a voltage is applied is not limited to the cross shape shown in fig. 13 (a). Therefore, the shape of the light-shielding layer 17 (the shape of the first light-shielding layer 17a and the second light-shielding layer 17b as viewed from the normal direction of the display surface) is not limited to the cross shape illustrated in fig. 1. For example, when the zigzag projection and/or slit disclosed in patent document 1 is used, the light shielding portion 17 may be formed in a zigzag shape.

In the description so far, the configuration in which the light shielding portion 17 is provided only on the TFT substrate 100a has been described, but depending on the alignment division method used, the light shielding portion may be provided only on the counter substrate 100b, or may be provided on both the TFT substrate 100a and the counter substrate 100 b.

Fig. 15(a) and (b) show another liquid crystal display device 100A according to this embodiment. The liquid crystal display device 100A is different from the liquid crystal display device 100 shown in fig. 2 and the like in that it has the light shielding portion 27 provided on the counter substrate 100 b.

The light shielding portion 27 provided on the counter substrate 100b is disposed at the boundary of the plurality of liquid crystal regions R. When a voltage is applied to the liquid crystal layer 30, the liquid crystal molecules 30a near the boundary of the liquid crystal region R are inclined so that the end on the substrate (i.e., the counter substrate 100b) side where the light shielding portion 27 is provided is away from the boundary, as can be seen from fig. 15 (b). Further, the light shielding portion 27 includes: the first light-shielding layer 27 a; and a second light-shielding layer 27b that overlaps the first light-shielding layer 27a with a predetermined gap therebetween. That is, the light shielding portion 27 is constituted by a plurality of light shielding layers 27a and 27b overlapping each other when viewed from the display surface normal direction.

The light shielding portion 27 provided as described above selectively shields, when viewed from an oblique direction (a direction inclined with respect to the normal direction of the display surface), a liquid crystal region R in which the liquid crystal molecules 30a fall back to the side opposite to the observer among 2 liquid crystal regions R adjacent to each other, that is, a liquid crystal region R in which the retardation value with respect to light in the oblique direction increases almost monotonically with an increase in voltage.

Fig. 16 schematically shows a region shielded from light by the light shielding portion 27 when the liquid crystal display device 100A is viewed from oblique directions V2 and V3. As shown in fig. 16(a), when viewed from the oblique direction V2, the light shielding portion 27 selectively shields the liquid crystal region R where the liquid crystal molecules 30a fall toward the side opposite to the observer (i.e., the left liquid crystal region R). As shown in fig. 16(b), the light shielding portion 27 selectively shields the liquid crystal region R on the side opposite to the observer (i.e., the right liquid crystal region R) from light when the liquid crystal molecules 30a are tilted in the oblique direction V3 from the opposite side. Therefore, the display characteristics when viewed from the oblique direction can be made close to those when viewed from the front direction, and display without a sense of misregistration can be realized.

Further, the light shielding portion 27 of the liquid crystal display device 100A includes: the first light-shielding layer 27 a; and a second light-shielding layer 27b that overlaps the first light-shielding layer 27a with a predetermined gap therebetween. Therefore, a decrease in the light transmittance in the front direction can be suppressed.

As described above, in the liquid crystal display device 100, the light shielding portion 17 is provided on the TFT substrate 100A, and in the liquid crystal display device 100A, the light shielding portion 27 is provided on the counter substrate 100b, so that the liquid crystal region R in which the liquid crystal molecules 30A are inclined to the side opposite to the viewer can be selectively shielded from light with respect to each of the liquid crystal display devices 100 and 100A.

The light shielding portion may be provided on any one of the substrates corresponding to a certain boundary between the plurality of liquid crystal regions R, and may be determined by focusing on the inclination of the liquid crystal molecules 30a in the vicinity of the boundary so that the end portion on the side of any one of the substrates is spaced apart from the boundary. That is, the light shielding portion may be provided such that the liquid crystal molecules 30a located near the boundary are inclined so that the end portion on the substrate side where the light shielding portion is provided is distant from the boundary when a voltage is applied.

Specifically, when the liquid crystal molecules 30a near the boundary are inclined so that the end on the TFT substrate 100a side is away from the boundary, the light shielding portion may be provided on the TFT substrate 100a, and when the liquid crystal molecules 30a near the boundary are inclined so that the end on the counter substrate 100b side is away from the boundary, the light shielding portion may be provided on the counter substrate 100 b. Therefore, when the 2 kinds of boundaries are mixed in the pixel, the light shielding portion may be provided in both the TFT substrate 100a and the counter substrate 100 b.

Fig. 17 shows another liquid crystal display device 100B according to this embodiment. The liquid crystal display device 100B includes a light shielding portion 27 provided on the counter substrate 100B in addition to the light shielding portion 17 provided on the TFT substrate 100 a.

As is clear from fig. 17, when a voltage is applied to the liquid crystal layer 30, the liquid crystal molecules 30a near the boundary (the left boundary in fig. 17) where the light shielding portion 17 is provided on the TFT substrate 100a are inclined such that the end on the TFT substrate 100a side is away from the boundary, and the liquid crystal molecules 30a near the boundary (the right boundary in fig. 17) where the light shielding portion 27 is provided on the counter substrate 100b are inclined such that the end on the counter substrate 100b side is away from the boundary. Therefore, the light shielding portions 17 and 27 can both selectively shield the liquid crystal region R in which the liquid crystal molecules 30a are inclined to the side opposite to the observer when viewed from the oblique direction. Therefore, the display characteristics when viewed from the oblique direction can be made close to those when viewed from the front direction, and display without a sense of misregistration can be realized. Further, since the light shielding portions 17 and 27 of the liquid crystal display device 100B have a multilayer structure, a decrease in light transmittance in the front direction can be suppressed.

Industrial applicability

The present invention can be suitably used for all alignment-division liquid crystal display devices including a vertical alignment liquid crystal layer. The liquid crystal display device of the present invention can be suitably used as a display portion of various electronic devices such as a mobile phone, a PDA, a notebook PC, a monitor, and a television receiver.

Claims (9)

1. A liquid crystal display device, characterized in that:

includes a first substrate; a second substrate; and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate and having a plurality of pixels,

the plurality of pixels respectively include: a first electrode provided on the liquid crystal layer side of the first substrate; a second electrode provided on the liquid crystal layer side of the second substrate; and the liquid crystal layer between the first electrode and the second electrode,

the liquid crystal layer in each of the plurality of pixels has a plurality of liquid crystal regions whose liquid crystal molecules are inclined in different orientations from each other when a voltage is applied between the first electrode and the second electrode,

each of the plurality of pixels has a light shielding portion arranged at a boundary of the plurality of liquid crystal regions,

the light shielding portion is provided on at least one of the first substrate and the second substrate such that, when a voltage is applied between the first electrode and the second electrode, liquid crystal molecules near the boundary are inclined such that an end portion on a side of the substrate where the light shielding portion is provided is distant from the boundary,

the light shielding portion includes: a first light-shielding layer; and a second light-shielding layer which overlaps with the first light-shielding layer with a predetermined gap therebetween.

2. The liquid crystal display device according to claim 1, wherein:

further comprises a pair of polarizing plates arranged in a crossed Nicol manner,

the liquid crystal molecules are inclined in each of the plurality of liquid crystal regions at an angle of approximately 45 ° to the polarizing axes of the pair of polarizing plates.

3. The liquid crystal display device according to claim 2, wherein:

the plurality of liquid crystal regions include 4 liquid crystal regions in which liquid crystal molecules are inclined to first, second, third, and fourth azimuths, a difference in any 2 of the first, second, third, and fourth azimuths is substantially equal to an integral multiple of 90 °, and azimuths in which liquid crystal molecules are inclined are substantially different by 90 ° in any 2 of the 4 liquid crystal regions adjacent to each other.

4. A liquid crystal display device, characterized in that:

includes a first substrate; a second substrate; and a vertical alignment type liquid crystal layer provided between the first substrate and the second substrate and having a plurality of pixels,

the plurality of pixels respectively include: a first electrode provided on the liquid crystal layer side of the first substrate; a second electrode provided on the liquid crystal layer side of the second substrate; and the liquid crystal layer between the first electrode and the second electrode,

the liquid crystal layer in each of the plurality of pixels has a plurality of liquid crystal regions whose liquid crystal molecules are inclined in different orientations from each other when a voltage is applied between the first electrode and the second electrode,

the plurality of liquid crystal regions include: a first liquid crystal region in which a retardation value of light incident on the liquid crystal layer from a direction inclined with respect to a normal direction of a display surface increases with an increase in applied voltage; and a second liquid crystal region in which the value of the retardation temporarily decreases and then increases with an increase in the applied voltage,

each of the plurality of pixels has a light shielding portion that is provided on at least one of the first substrate and the second substrate and that selectively shields the first liquid crystal region when viewed from a direction inclined with respect to a display surface normal direction,

the light shielding portion includes: a first light-shielding layer; and a second light-shielding layer which overlaps with the first light-shielding layer with a predetermined gap therebetween.

5. The liquid crystal display device according to claim 4, wherein:

further comprises a pair of polarizing plates arranged in a crossed Nicol manner,

the liquid crystal molecules are inclined in each of the plurality of liquid crystal regions at an angle of approximately 45 ° to the polarizing axes of the pair of polarizing plates.

6. The liquid crystal display device according to claim 5, wherein:

the plurality of liquid crystal regions include 4 liquid crystal regions in which liquid crystal molecules are inclined to first, second, third, and fourth azimuths, a difference in any 2 of the first, second, third, and fourth azimuths is substantially equal to an integral multiple of 90 °, and azimuths in which liquid crystal molecules are inclined are substantially different by 90 ° in any 2 of the 4 liquid crystal regions adjacent to each other.

7. The liquid crystal display device according to any one of claims 2, 3, 5, and 6, wherein:

the first electrode has: a cross-shaped main section arranged to overlap with the polarization axes of the pair of polarizing plates; and a plurality of branch portions extending from the trunk portion in a direction of substantially 45,

the light shielding part is arranged on the first substrate.

8. The liquid crystal display device according to any one of claims 1 to 6, further comprising:

a pair of vertical alignment films disposed between the first electrode and the liquid crystal layer and between the second electrode and the liquid crystal layer; and

an alignment maintaining layer composed of a photopolymer formed on each surface of the pair of vertical alignment films on the liquid crystal layer side, and defining a pretilt azimuth of liquid crystal molecules of the liquid crystal layer when no voltage is applied to the liquid crystal layer.

9. The liquid crystal display device according to claim 7, further comprising:

a pair of vertical alignment films disposed between the first electrode and the liquid crystal layer and between the second electrode and the liquid crystal layer; and

an alignment maintaining layer composed of a photopolymer formed on each surface of the pair of vertical alignment films on the liquid crystal layer side, and defining a pretilt azimuth of liquid crystal molecules of the liquid crystal layer when no voltage is applied to the liquid crystal layer.