JPH07311383A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device of a wide visual field angle by dividing display pixels and specifying orientation vectors of liquid crystal directors. CONSTITUTION:This liquid crystal display device has the following structure, in which inclined parts 13L, 13R for orientation control are formed by interposing section layers 12 for orientation control in the lower layers at the peripheral edges of the display pixel regions of lower transparent electrodes 11 to build up the contact surfaces with a liquid crystal layer 30 and inclined parts 23L, 23R for orientation control are also formed by interposing sectional layers 22S for orientation control in the lower layers within the display pixel regions of upper transparent electrodes 21. The orientation directions of the liquid crystal directors 31 are controlled by these inclined parts 13L, 13R, 23L, 23R and the orientation states are made uniform in the respective zones divided into the right and left zones by the effect of the continuum characteristic of the liquid crystals. In addition, the dependency on the visual angles is lessened by making the orientation vectors of respective zones different from each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which achieves wide viewing angle characteristics and high display quality by controlling the orientation of a liquid crystal director.

[0002]

2. Description of the Related Art Liquid crystal display devices have advantages such as small size, thin shape and low power consumption, and are being put to practical use as display devices in the fields of OA equipment, AV equipment and the like. In a liquid crystal display device, two substrates, each having a transparent electrode of a predetermined pattern provided on a transparent substrate such as glass, are bonded together with a liquid crystal layer having a thickness of several μm sandwiched therebetween, and the polarization axes are orthogonal to each other. It is configured by sandwiching between two polarizing plates. In particular, the matrix type in which the liquid crystal is driven by arbitrarily selecting the intersection point where the scanning electrode group and the data electrode group are crossed and applying a voltage to the display pixel capacitance can drive tens to hundreds of thousands of pixels. It is possible and suitable for a large-screen, high-definition display device.

FIG. 21 shows a general plane structure thereof. Both the scanning electrode (X) and the data electrode (Y) are made of a transparent conductive film such as ITO. Each of these is formed on a transparent substrate such as a glass which is arranged above and below with a liquid crystal interposed therebetween, and the intersection of both electrodes (X, Y) serves as a display pixel capacitance. A signal voltage is applied to both electrodes (X, Y) by time division driving. By driving the liquid crystal by applying an effective voltage equal to or more than the threshold value to the display pixel serving as the selection point, a set of display points with changed transmittance is visually recognized as a display image such as a character or an image.

FIG. 22 shows T as a switching element for selection.
This is an active matrix type planar structure using an FT (Thin Film Transistor). In the active matrix type, the scanning signal gate line (G) and the data signal drain line (D) are formed on the same substrate. At the intersection of both lines (G, D),
A TFT using a non-single crystal semiconductor layer such as a-Si or p-Si as an active layer is formed and connected to the display electrode (P). The counter electrode is formed over the entire surface of the other substrate, which is arranged so as to face the liquid crystal layer, and each portion facing the display electrode (P) serves as a display pixel capacitance. The display electrode (P) and the counter electrode are made of a transparent conductive film such as ITO. The gate line (G) is line-sequentially scanned and selected, all the TFTs on the same scanning line are turned on, and a data signal synchronized with this is supplied to each display electrode (P) via the drain line (D). A voltage is also set in the counter electrode in synchronization with the scanning of the gate line (G), and the liquid crystal is driven by the voltage difference between the display electrodes (P) facing each other.
The OFF resistance of the FT holds the voltage applied to the display pixel capacitance, and the driving state of the liquid crystal is continued.

FIG. 23 is a sectional view showing a cell structure of such a liquid crystal display device. Transparent substrate (200, 210)
The transparent electrodes (201, 211) serving as the scanning electrodes, the display electrodes, and the data electrodes or the counter electrodes are provided on the upper side, respectively.
Are formed and are located above and below the liquid crystal layer (220). In addition, an alignment film (230, 2) made of a polymer film such as polyimide is formed on the transparent electrodes (201, 211).
40) is coated, and the surface orientation is controlled by applying a rubbing treatment. Further, although not shown, polarizing plates are provided outside the substrates (200, 210) so that their polarization axis directions are orthogonal to each other.

The liquid crystal layer (220) is a nematic liquid crystal in which a chiral material is mixed to give directivity in a twist direction. The liquid crystal having the positive dielectric anisotropy is aligned parallel to the substrate surface as described above, but is in an initial alignment state having a slight initial tilt (pretilt) angle along the rubbing direction. The rubbing is performed on the two substrates (200, 210) in directions orthogonal to each other, and the liquid crystal is 90 ° between the upper and lower substrates.
It is arranged twisted at °. FIG. 24 is a perspective view schematically showing this state. Both the upper and lower substrates are rubbed in the directions indicated by the arrows. On the contact surface, the liquid crystal director (221) is raised by a pretilt in the rubbing direction, and accordingly, the liquid crystal director (221) is twisted and arranged clockwise from bottom to top. This type of liquid crystal display device is called a TN (Twisted Nematic) system. In the TN method, a voltage is applied to the liquid crystal layer (220) to eliminate the twisted state, whereby transmitted light is controlled to obtain bright and dark (black and white).

FIG. 25 shows a cell using a liquid crystal having a negative dielectric constant anisotropy as the liquid crystal layer (250). Although the electrode arrangement is the same as that of the TN method shown in FIG. 23, the liquid crystal is initially aligned in the vertical direction of the substrate due to the excluded volume effect of the alignment films (260, 270) formed for vertical alignment. . This is because the liquid crystal director (251) is arranged in parallel with the polymer component of the alignment films (260, 270) grown in the direction perpendicular to the substrate, so that the volume occupied by the polymer and the liquid crystal molecules are increased. The mutual exclusion volume caused by the contact of the occupied volume of the is minimized. As such a type, for example, by changing the orientation of the liquid crystal from the initial state by applying an electric field and changing the birefringence of incident light, ECB (Elec
trically controlled birefringence) method.

[0008]

The problems of the conventional liquid crystal display device will be described below. FIG. 26 is a plan view of the direction of the liquid crystal director when the TN cell is viewed from above. The dotted arrow is the lower rubbing direction, and the solid arrow is the upper rubbing direction. As can be seen from FIG. 24, the liquid crystal director (221)
Stands up in the direction indicated by the dotted arrow on the lower side and rises in the direction indicated by the solid arrow on the upper side. When the orientation vector is oriented upward in the long axis direction of the liquid crystal, the liquid crystal directors in the cell all have an orientation vector within the angular range indicated by the double arrow. In the intermediate layer of the liquid crystal in the halftone, the liquid crystal director is represented by the alignment vector indicated by the thick arrow, and is considered to be in the state of this alignment vector even in all gray scales and all liquid crystal layers. Since the alignment state of the liquid crystal relative to the optical path also changes relative to the change in the viewing angle, the gradation approaches white when viewed from the right side of the paper, and approaches black when viewed from the left, compared to viewing from the front. The viewing angle dependency in the left-right direction was high.

FIG. 27 is a plan view showing a light transmission state during driving of a conventional vertical alignment type ECB type liquid crystal display device. Although omitted in the above description, a light-shielding film made of metal or the like is usually provided on the counter substrate side and blocks light transmission except for the openings (300) corresponding to the pixels arranged in a matrix. There is. In the light-shielding region (301), light leakage between pixels is prevented and the pixel becomes black to improve the display contrast ratio. Although the light transmittance is controlled in each opening (300) to obtain a desired display, a black region called a disclination (302) also occurs in this opening (300). The disclination is a region in which, when there are a plurality of regions having different liquid crystal orientation vectors, the alignment of the liquid crystal director is disturbed on the boundary line, and the transmittance is different from other regions.

In the nematic liquid crystal director, the orientation vector when a voltage is applied is restricted only by the angle with respect to the electric field direction, and the azimuth angle about the electric field direction is released.
Therefore, the orientation vectors are mutually different due to factors such as unevenness of the surface alignment process due to the electrodes on the substrate surface and the presence of a lateral electric field due to the potential difference between the electrodes in the cell. Different areas arise. If the orientation vector is partially abnormal, the continuity of the liquid crystal causes the orientation vector having an azimuth angle to follow it to spread over a certain region. If such a phenomenon occurs at a plurality of locations in the cell, a plurality of regions having orientation vectors having different azimuth angles while having the same angle with the electric field direction are generated. The boundary lines of these areas have discrepancies because they have different transmittances. If many disclinations with different shapes occur for each pixel, problems such as graininess on the screen and failure to obtain the expected color display may occur.

Further, if the orientation vector of each area becomes irregular in the display area, there is a problem that the viewing angle dependency increases. Further, there is a problem of so-called electrostatic breakdown in which static electricity generated during rubbing causes changes in the threshold value of the TFT and the mutual conductance.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. First, two substrates having transparent electrodes on the opposite surface side are bonded to each other with a liquid crystal layer interposed therebetween. In a liquid crystal display device in which display pixels formed by opposing portions of both electrodes are arranged in a matrix, a contact surface with the liquid crystal layer is provided in the periphery or / and region of at least one of the display pixels of the electrode. An alignment control tilting part formed by partially raising or lowering is provided, and the alignment of the liquid crystal is controlled by the alignment control tilting part.

Secondly, in the first configuration, the orientation control inclined portion is formed by partially elevating the electrode by an orientation control slice provided under the electrode. is there. Thirdly, in the first configuration, the alignment control tilting portion is provided in a region of the display pixel, divides the display pixel into a plurality of parts, and divides the liquid crystal of each part of the display pixel. The orientation is different.

Fourthly, in the first configuration, an alignment control window formed by the absence of an electrode is provided in at least one of the display pixel regions of the electrodes, and is controlled by the alignment control inclination portion. This is a configuration in which the alignment of the generated liquid crystal is further controlled.

[0015]

In the inclined portion formed by raising or recessing the substrate surface in the first configuration, the liquid crystal director having positive or negative dielectric anisotropy has an initial orientation direction with respect to the inclined surface. It is controlled to be parallel or vertical and has a predetermined angle with the electric field direction. Therefore, the tilt direction is constrained so as to tilt to the energy-stable state at the shortest by applying a voltage, and the orientation vector is determined together with the electric field effect based on the dielectric anisotropy.

As described above, when the orientation vector is determined by the orientation control inclination portion, the region having the same orientation vector is caused by some other action such as an electrode or another orientation control inclination portion due to the continuity of the liquid crystal. It spreads until it is limited to the part that received it. Therefore, by arranging the orientation control inclined portion in a predetermined shape around the display pixel region and in the region, the orientation vectors are uniformly aligned in the zone defined by these actions, and the display characteristics are improved.

In the second structure, the alignment control layer is disposed under the electrode, and the alignment control layer is formed under the electrode, whereby the electrode is partially raised to form an alignment control sloped portion in which the contact surface with the liquid crystal layer is raised or depressed. To be done. In the third configuration, each zone in the display pixel area divided into a plurality of parts by the orientation control inclined portion provided in the display pixel area has a different preferential viewing angle direction from each other, so that one display pixel has priority. The viewing angle direction is widened, and viewing angle dependence can be reduced.

In the fourth structure, since the alignment control window, which is an absent portion of the electrode, is provided in the area of the display pixel, the electric field is weak in the corresponding liquid crystal layer and is below the threshold for driving the liquid crystal. , The liquid crystal director is held in the initial alignment state. The boundaries between the zones of the liquid crystal layer, which are controlled to have different alignment states by the alignment control tilt portions, are fixed by the alignment control window to stabilize the alignment and further improve the display characteristics.

[0019]

EXAMPLES The present invention will be described in detail below based on examples. First, a first embodiment will be described with reference to FIGS. FIG. 1 is a sectional view of a TN liquid crystal cell according to this embodiment. Transparent electrodes (11, 21) made of ITO are provided on two transparent substrates (10, 20) which are vertically attached to each other with a liquid crystal layer (30) interposed therebetween. An insulating material is interposed below the lower transparent electrode (11) to serve as an alignment control layer (12S), and the transparent electrode (11) is raised at both ends of the display pixel section. On the other hand, the upper transparent electrode (2
Insulation is also interposed under the lower part of 1), and the orientation control fault (22
As S), the transparent electrode (21) is formed inside the display pixel area.
Has been raised. The orientation control layers (12, 22) are both formed by etching SiN _x , SiO _2, or the like. S on the transparent electrodes (11, 21), respectively.
An orientation film (40, 50) is formed by covering the entire surface with an iO oblique vapor deposition film or an LB film (Langmuir-Blodgett film). A parallel alignment structure having a pretilt angle of 0 ° is realized by the alignment films (40, 50). In the oblique vapor deposition of SiO, by performing vapor deposition at an angle of 60 ° from the normal line of the substrate, parallel alignment with a pretilt angle of 0 ° can be obtained in a direction perpendicular to the vapor deposition direction. The LB film is a film in which monomolecular films adsorbed on the water surface are accumulated on the substrate surface, and as an alignment film, the substrate is moved vertically by moving the substrate vertically across the water surface. A parallel alignment film having a pretilt angle of 0 ° can be obtained. The liquid crystal layer (30) is a nematic liquid crystal having a positive dielectric anisotropy, and by mixing a chiral material, the liquid crystal director (31) is easily twisted, and the alignment film (40, 50) is provided on the contact surface. Under the control of 1), the two substrates are twisted at 90 °. Alignment film (40,
50) is an orientation control inclined portion (13L, 13R, 23L, 2) in which the slope of the portion raised by the orientation control slice (12S, 22S) has an inclined contact surface with the liquid crystal layer (30).
3R).

When the cell of this structure is driven, the liquid crystal director (31) is moved from the opposite sides in the left and right regions according to the alignment control inclined portions (13L, 13R) at both ends of the lower electrode (11). Can be launched. In addition, in the central portion of the upper electrode (21), the orientation control inclined portion (23L,
23R) causes the opposite sides to rise. That is,
Due to the continuity of the liquid crystal, in the zone on the left side of the figure, the upper and lower alignment control tilt portions (13L, 2L) sandwiching the liquid crystal layer (30) are provided.
The liquid crystal director (31) is entirely activated from the left side by the action of 3 L), and the liquid crystal director (31) is entirely activated from the right side by the action of the alignment control inclined portions (13R, 23R) in the right zone. To be In this way, the orientation control inclined portions (13L, 13R, 23L, 2
By disposing 3R), the display pixel is divided into two zones having different orientation vectors, and a uniform orientation state is obtained in each zone.

FIG. 2 is a plan view of the display pixel portion, showing a structure in which the upper and lower electrodes (10, 20) facing each other are viewed from above. There is a strip-shaped region of the lower orientation control inclined portion (13L, 13R) along the left and right ends, and a central portion parallel to this is a strip-shaped region of the upper orientation control inclined portion (23L, 23R). . The dotted line is the orientation direction of the lower substrate (10), and the solid line is the orientation direction of the upper substrate (20).
The liquid crystal director is accordingly rotated 90 ° clockwise from bottom to top. Thick arrows are projections of the orientation vector in the intermediate layer of the halftone and the liquid crystal onto the plane. As can be seen from the figure, two zones (L,
In R), the orientation vectors are oriented in opposite directions. That is, the liquid crystal director is started up from the initial state along the same parallel alignment direction on the opposite side in the left and right zones (L, R). Also, with respect to the upper and lower substrates, the opposite sides are raised to smooth the continuity of the liquid crystal director. The orientation vector indicated by the thick arrow is
It can be considered that the liquid crystal director is in this state on average for all gradations and all liquid crystal layers in the zone.

With such a cell structure, for visual recognition from the left side of the paper, for example, the gradation of the zone (L) is closer to black than that of the visual recognition from the front, and the gradation of the zone (R) is closer to white. Therefore, the average tone of both zones (L, R) approaches the visual recognition from the front. Since there is a similar averaging effect for the visual recognition from the right direction, the viewing angle dependency in the horizontal direction is reduced.

Hereinafter, as in the first embodiment, a nematic liquid crystal having a positive dielectric anisotropy mixed with a chiral material is used as a liquid crystal layer, and a TN liquid crystal cell having a parallel alignment structure without a pretilt angle is used. The second to fifth embodiments of the present invention will be described in which the orientation of the liquid crystal director is controlled by the orientation control tilting portion and the display pixel is divided into a plurality of portions to reduce the viewing angle dependency.

(Second Embodiment) Since this embodiment is similar to the first embodiment, detailed description thereof will be omitted. FIG. 3 is a sectional view of the cell structure. The first embodiment differs from the first embodiment shown in FIG. 1 in that instead of the orientation control tilt portion on the upper substrate (20),
The point is that an alignment control window (24), which is an electrode absent portion, is formed in the center of the transparent electrode (21). The orientation control window (24) is opened in the transparent electrode (21) by etching or the like after forming the ITO film. In the region corresponding to the alignment control window (24), an electric field is not generated in the liquid crystal layer (30),
Alternatively, the liquid crystal director (31) is fixed in the initial alignment state because it is weak and equal to or less than the drive threshold of the liquid crystal. Therefore, the orientation control sloped portion (1) of the lower substrate (10) is
The alignment state controlled from both sides of the display pixel portion by (3L, 13R) is divided by the alignment control window (24) so that the boundary between two zones having different alignment vectors is fixed by the continuity of the liquid crystal.

Although the orientation control window (24) has no electrode, the electrode exists in the region of the lower transparent electrode (11) facing the orientation control window (24). Therefore, the orientation control window (24)
In the liquid crystal layer (30) corresponding to (3), an electric field is obliquely generated in the shape shown by the dotted line in FIG. The liquid crystal director (31) having a positive dielectric anisotropy is oriented in the electric field direction, but is inclined so as to be oriented in the electric field direction at the shortest from the initial orientation state. That is, the liquid crystal director (31) is raised from the left side in the area corresponding to the left edge of the alignment control window (24), and the liquid crystal director (31) in the area corresponding to the right edge of the alignment control window (24). ) Is launched from the right side. Thus, in this way, the upper substrate (20)
By providing the alignment control window (24) on the alignment control window (24), the alignment control inclined portion (13
Together with the action of L), the liquid crystal director (31) is all raised from the left side and the alignment control window (24).
In the zone on the right side, the liquid crystal directors (31) are all raised from the right side together with the action of the alignment control inclined portion (13R).

FIG. 4 shows a plan view. Orientation control window (24)
In the two zones (L, R) partitioned by, the liquid crystal directors are raised on the opposite sides from the initial state along the same parallel alignment direction, as in the first embodiment shown in FIG. Therefore, since the visual recognition from the left and right directions is recognized by the average tone of both zones (L, R), the viewing angle dependency is reduced.

(Third Embodiment) FIG. 5 shows a sectional structure of a cell. 2 which are laminated on top of each other with the liquid crystal layer (30) in between.
Transparent electrodes (11, 21) made of ITO are provided on the transparent substrates (10, 20). Below the lower transparent electrode (11), an alignment control slice (12L) formed on most of the display pixel portion and an alignment control slice (12L) are formed.
A second alignment control layer (15) formed inside the display pixel section on L) is provided. Both transparent electrodes (11, 2
1) The entire surface is covered with an alignment film (40, 50) made of an oblique vapor deposition film of SiO or an LB film. The alignment control layer (12L) raises the transparent electrode (11) as a whole, and the transparent electrode (11) is relatively depressed at both ends of the display pixel portion where the alignment control layer (12L) is absent to align. The film (40) has an inclined surface, which serves as an orientation control inclined portion (14L, 14R). In addition, the second alignment control layer (15) partially bulges the transparent electrode (11), and the slope of the alignment film (40) also has the alignment control sloped portion (1) in this part.
6L, 16R).

The display pixel area has an alignment control sloped portion (14
L, 16L) and the right side zone defined by the orientation control slopes (14R, 16R). That is, in the zone on the left side, the liquid crystal director (3
1) are all started from the right side, and in the right zone, the liquid crystal directors (31) are all started from the left side.

FIG. 6 shows a plan view of the display pixel portion. Alignment control slopes (14L, 1) along the left and right edges of the display pixel.
4R), and in parallel with this, there is a strip-shaped region of the alignment control inclined portion (16L, 16R) in the center of the display pixel. In this way, the two zones (L,
In R), the liquid crystal directors are raised on the opposite side from the same parallel alignment state, and the plane projection of the average alignment vector represented by the thick arrow points in the opposite direction.

With such a cell structure, for visual recognition from the left side of the paper, for example, the gradation of the zone (L) is closer to white than the visual recognition from the front, and the gradation of the zone (R) is closer to black. Therefore, the average tone of the zones (L, R) approaches the visual recognition from the front. Since the same effect is exerted when viewed from the right direction, the viewing angle dependency in the left and right directions is reduced.

(Fourth Embodiment) This embodiment is different from the third embodiment as shown in FIG. 7, as shown in FIG. 7, an alignment control inclined portion (25L) is formed on the upper substrate (20) as a display pixel dividing means. ，
25R) is provided. Below the lower transparent electrode (11), an alignment control layer (12L) formed on most of the display pixel portion is interposed, and the slopes of the alignment film (40) are formed on the left and right ends of the alignment control slope portion (12L). 14L, 14R)
Has become. Below the upper transparent electrode (21), an alignment control layer (22L) is provided on most of the display pixel section.
A non-existing portion is formed by vertically cutting the central portion of the display pixel by etching or the like. In this absent part, the transparent electrode (21)
Are depressed, and as a result, a slanting surface is formed on the alignment film (50) to form the alignment control inclined portions (25L, 25R). The liquid crystal directors (31) are all raised from the right side in the zone on the left side defined by the alignment control tilt portions (14L, 25L), and the liquid crystal director (31) in the zone on the right side defined by the alignment control tilt portions (14R, 25R). Lector (31)
Are all launched from the left side.

FIG. 8 shows a plan view of the display pixel portion. Alignment control slopes (14L, 1) along the left and right edges of the display pixel.
4R) strip-shaped region, and in parallel with this, there is a strip-shaped region of the orientation control inclined portion (25L, 25R) in the center of the display pixel. Thus, two zones (L,
In R), as in the third embodiment, the plane projection of the orientation vector is in the opposite direction, and both zones (L, R)
By the average tone of, the viewing angle dependency in the left-right direction is reduced.

(Fifth Embodiment) In this embodiment, as a means for dividing the display pixel area, as shown in FIG.
The alignment control window (17) described in the second embodiment is formed in (0). That is, the alignment control window (17) is opened by forming the alignment control sloped portions (14L, 14R) on the lower substrate (10) and forming an electrode absent portion in the lower transparent electrode (11) by etching. Has been done. As a result, the boundaries of the alignment states controlled separately by the alignment control slopes (14L, 14R) on both sides of the display pixel are fixed by the alignment control window (17).

In the region corresponding to the alignment control window (17), an oblique electric field as shown by a dotted line in the figure is generated in the liquid crystal layer (30), so that the alignment control tilted portions (14L, 14R) work together. , In the left zone, the liquid crystal director (3
1) are all launched from the right side, and in the right zone all are launched from the left side. FIG. 10 shows a plan view of the display pixel portion. There are strip-shaped regions of the alignment control inclined portions (14L, 14R) along the left and right sides of the display pixel, and in parallel with this, there is a strip-shaped region of the alignment control window (17) at the center of the display pixel. In the two zones (L, R) divided into left and right by the orientation control window (17), as in the third and fourth embodiments,
The plane projection of the orientation vector is in the opposite direction,
The average tone of both zones (L, R) reduces the viewing angle dependency in the left-right direction.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. 11 and 12. FIG. 11 is a cross-sectional view of a vertical alignment ECB type liquid crystal cell according to this embodiment. A transparent electrode (1) of ITO is formed on two transparent substrates (100, 110) which are vertically laminated with a liquid crystal layer (120) interposed therebetween.
01, 111) are provided. Lower transparent electrode (1
In the lower part of (00), an insulator is interposed and an orientation control fault (1
02S) as a transparent electrode (1
01) is raised. On the other hand, the upper transparent electrode (11
Insulation is also interposed under the lower part of 1), and the orientation control fault (11
2S), the transparent electrode (111) is raised in the portion along the diagonal line of the display pixel. Orientation control fault (102
Both S, 112S) are formed by etching SiN _x , SiO _2, or the like. Transparent electrode (101,
111) is covered with a vertical vapor deposition film of SiO or a polyimide film to form an alignment film (130, 140). The liquid crystal layer (120) is a nematic liquid crystal having negative dielectric anisotropy, and the initial alignment of the liquid crystal director (121) is perpendicular to the contact surface due to the excluded volume effect of the alignment films (130, 140). You are controlling in the direction. The alignment films (130, 140) are the alignment control slices (102S, 11).
The slope of the portion raised by 2S) is the liquid crystal layer (12S).
0) The contact surface with the orientation control inclined portion (10
3, 113L, 113R, 113U, 113D) (see FIG. 12).

When the cell of this structure is driven, the liquid crystal director (121) is tilted to the opposite side in the left and right regions according to the alignment control tilting part (103) at the peripheral part of the lower electrode (101). Further, the central portion of the upper electrode (111) is also tilted to the opposite side by the orientation control tilting portions (113L, 113R). That is, because of the continuity of the liquid crystal, the liquid crystal layer (12
0) sandwiching the upper and lower orientation control inclined portions (113L, 10
By the action of 3), all the liquid crystal directors (121) are tilted to the right side, and in the zone on the right side, the liquid crystal directors (121) are all tilted to the left side by the action of the alignment control tilting portions (113R, 103). By arranging the orientation control inclined portions (103, 113L, 113R) in this way, the display pixel is divided into a plurality of zones having different orientation vectors, and a uniform orientation state is obtained in each zone.

FIG. 12 is a plan view of the display pixel portion, showing a structure in which the upper and lower electrodes (101, 111) facing each other are viewed from above. There is a strip-shaped region of the lower alignment control sloped portion (103) surrounding the periphery of the display pixel, and the alignment control sloped portion (1) formed on the upper side along the diagonal line of the display pixel is provided inside.
13L, 113R, 113U, 113D). The thick arrow is the plane projection of the orientation vector in the halftone, and the liquid crystal Dilek is considered to be in this state on average for all gray levels. The arrow direction indicates the direction in which the liquid crystal director tilts its upper side. As is clear from the figure, the orientation control inclined portions (113L, 113R,
In the four zones (U, D, L, R) divided vertically and horizontally by (113U, 113D), the orientation vector is directed in each of the four directions. That is, the liquid crystal directors are tilted from the same initial vertical alignment state in each of the four upper, lower, left and right zones (U, D, L, R) in each of the four directions. Note that the operation described above with reference to FIG.
In regard to the cross section of the L-R region,
It goes without saying that the same effect is exerted on the cross section of the −D region.

With such a cell structure, for visual recognition from the left side of the paper, for example, the gradation of the zone (L) is closer to white than the visual recognition from the front, and the gradation of the zone (R) is closer to black. Therefore, the average tone of both zones (L, R) and the combined light of the upper and lower zones (U, D) come closer to being visually recognized from the front. The same averaging effect is also exerted on the visual recognition from other directions, so that the viewing angle dependency is reduced for all the directions.

Further, by controlling the alignment state of the liquid crystal director in this manner, the boundary line of the regions having different alignment vectors, that is, the disclination is
Alignment control slopes (113L, 113) for all pixels
R, 113U, 113D) fixed in the X-shaped area,
Variations between pixels can be suppressed. Hereinafter, similarly to the sixth embodiment, for the ECB liquid crystal cell having the vertical alignment structure using the nematic liquid crystal having the negative dielectric constant anisotropy as the liquid crystal layer, the alignment of the liquid crystal director is controlled by the alignment control tilt portion. The seventh to tenth embodiments of the present invention in which the display pixel is divided into a plurality of portions to reduce the viewing angle dependency will be described.

(Seventh Embodiment) Since this embodiment is similar to the sixth embodiment, detailed description thereof will be omitted. FIG. 13 is a sectional view of the cell structure. The sixth embodiment differs from the sixth embodiment shown in FIG. 11 in that the upper substrate (110) does not have an alignment control slope, but the alignment is a non-electrode portion in the transparent electrode (111) along the diagonal line of the display pixel. That is, a control window (114) is formed. The orientation control window (114) is opened by etching after forming the ITO film. Orientation control window (1
In the region corresponding to 14), an electric field is not generated in the liquid crystal layer (120), or the liquid crystal director (121) is fixed in the initial alignment state because it is weak or less than the drive threshold of the liquid crystal. Therefore, the orientation control inclined portion (103)
Due to the continuity of the liquid crystal, the alignment state controlled from the peripheral edge of the display pixel section is divided by the alignment control window (114) fixing the boundaries of both zones having different alignment vectors.

Although the orientation control window (114) has no electrode, the electrode exists in the region of the lower transparent electrode (101) facing the orientation control window (114). Therefore, the orientation control window (1
In the liquid crystal layer (120) corresponding to 14), an electric field is obliquely generated in the shape shown by the dotted line in FIG. The liquid crystal director (121) having negative dielectric anisotropy is oriented in a direction perpendicular to the electric field direction, but tilts so as to be oriented in the direction perpendicular to the electric field at the shortest from the initial alignment state. That is,
The liquid crystal director (121) is tilted to the right in the area corresponding to the left edge of the alignment control window (114), and the liquid crystal director (121) is left in the area corresponding to the right edge of the alignment control window (114). Can be tilted. Therefore, as described above, the alignment control window (11) is formed on the upper substrate (110).
By providing 4), in the zone on the left side of the alignment control window (114), the liquid crystal director (121) is tilted to the right all together with the action of the alignment control tilting portion (103), and the alignment control window (114) is also provided. In the zone on the right side, the liquid crystal directors (121) are all tilted to the left together with the action of the alignment control tilting portion (103).

FIG. 14 shows a plan view. In each of the zones (U, D, L, R) divided into four by the X-shaped alignment control window (114), the liquid crystal director is the same as in the sixth embodiment shown in FIG. The same initial vertical alignment state is tilted in each of the four directions. Therefore, for viewing from all directions, each zone (U, D, L,
Since it is recognized by the average tone of R), the viewing angle dependency is reduced, and the variation in disclination is suppressed, so that the display quality is improved.

(Eighth Embodiment) FIG. 15 shows a sectional structure of a cell. Transparent electrodes (101, 111) of ITO are provided on two transparent substrates (100, 110) which are vertically laminated with a liquid crystal layer (120) interposed therebetween. Below the lower transparent electrode (101), the alignment control layer (102L) formed on most of the display pixel section and the diagonal line of the display pixel section on the alignment control section (102L) are formed. A second orientation control slice (105) is provided. A vertical alignment film (130, 1) made of a vertical vapor deposition film of SiO or a polyimide film is formed on both transparent electrodes (101, 111).
40) is entirely coated. Orientation control fault (102
L) raises the transparent electrode (101) as a whole and at the same time, the alignment control layer (102) is formed at the peripheral portion surrounding the display pixel.
In the portion where L) is absent, the transparent electrode (111) is relatively depressed, and the orientation film (130) has a slope, which serves as an orientation control inclined portion (104). Second orientation control slice (10
In 5), the transparent electrode (111) is partially raised, and the orientation control inclined portions (106L, 106R, 106U, 106D) are formed (see FIG. 16).

The display pixel region has an alignment control sloped portion (10
No. 4,106L) and a zone on the right side defined by the orientation control slopes (104, 106R). That is, in the left zone, the liquid crystal directors (121) are all tilted to the left side according to the alignment control tilting portions (104, 106L), and in the right side zone, all the liquid crystal directors (121) are tilted to the right side.

FIG. 16 shows a plan view of the display pixel portion. There is a strip-shaped region of the alignment control sloped portion (104) at the periphery of the display pixel, and the alignment control sloped portion (106L, 106R, 106U, 106) formed along the diagonal line of the display pixel is inside.
There is an X-shaped area in D). In each of the four zones (U, D, L, R) thus divided, the liquid crystal directors are tilted in the respective four directions from the same initial vertical alignment state, and are represented by thick arrows. The plane projection of the orientation vector is in four directions.

With such a cell structure, for visual recognition from the left side of the paper surface, for example, the gradation of the zone (L) is closer to black than the visual recognition from the front, and the gradation of the zone (R) is closer to white. Therefore, the average tone of the zones (L, R) and the combined light of the upper and lower zones (U, D) come closer to the visual recognition from the front. The same averaging effect is also exerted on the visual recognition from other directions, so that the viewing angle dependency is reduced for all the directions.

Further, by controlling the alignment state of the liquid crystal director in this manner, the boundary line of the regions having different alignment vectors, that is, the disclination is
Alignment control slopes (106L, 106L) for all pixels
R, 106U, 106D) fixed in the X-shaped area,
Variations between pixels can be suppressed. (Ninth Embodiment) This embodiment is different from the eighth embodiment in that as shown in FIG.
On the upper substrate (110), the orientation control inclined portions (115L, 11
5R) is provided. Lower transparent electrode (1
The alignment control layer (102L) formed in the majority of the display pixel portion is interposed below the display element 01), and the peripheral edge portion is the alignment control inclined portion (104). Upper transparent electrode (11
An alignment control layer (112L) is provided on the entire lower surface of 1), and an absent portion is formed along the diagonal line of the display pixel by etching or the like. In this absent portion, the transparent electrode (111) is depressed to form a slope on the alignment film (130), and the alignment control tilted portions (115L, 115R, 115U,
115D). Orientation control inclined part (104, 1
15L), the liquid crystal directors (121) are all tilted to the left in the left zone, and the liquid crystal directors (121) are all in the right zone defined by the alignment control tilting portions (104, 115R). Tilt to the right.

FIG. 18 shows a plan view of the display pixel section. There is a strip-shaped region of the alignment control sloped portion (104) surrounding the periphery of the display pixel, and the alignment control sloped portion (115L, 115R, 115U, 1) formed along the diagonal line of the display pixel is provided inside.
15D) has an X-shaped area. In each of the zones (U, D, L, R) divided into four in this way, the plane projection of the orientation vector is in each of the four directions, as in the eighth embodiment. Zone (U, D, L, R)
The average tone reduces the viewing angle dependency in all directions and suppresses disclination variations.

(Tenth Embodiment) In this embodiment, as a display pixel region dividing means, as shown in FIG. 19, a lower substrate (100) is provided with an alignment control window (1) described in the seventh embodiment.
07) is formed. That is, the orientation control inclined portion (104) is formed on the lower substrate (100), and the electrode absent portion is formed by etching in the lower transparent electrode (101). As a result, the boundaries of the alignment states controlled separately by the alignment control groove (103) on both sides of the display pixel are fixed by the alignment control window (107).

In the region corresponding to the alignment control window (107), an oblique electric field as shown by a dotted line in the figure is generated in the liquid crystal layer (120), and therefore, in combination with the action of the alignment control tilting portion (104), the left side is formed. In the zone of the liquid crystal director (121)
Are all tilted to the left and in the right zone are all tilted to the right. FIG. 20 shows a plan view of the display pixel portion. There is a band-shaped region of the alignment control sloped portion (104) surrounding the periphery of the display pixel, and inside there is an X-shaped region of the alignment control window (107) formed along the diagonal line of the display pixel. Each zone (U, divided into four by the orientation control window (107)
D, L, R), as in the eighth and ninth embodiments, the plane projections of the orientation vector are in the four respective directions, and each of the zones (U, D, L, R) has a plane projection. The average tone reduces the viewing angle dependency in all directions and suppresses the disclination variation.

[0051]

As is apparent from the above description, by disposing the orientation control inclined portion at a predetermined portion of the cell, the display pixel can be divided into a plurality of zones each having a different preferential viewing angle direction. It was Therefore, in the TN cell, by dividing the display pixel into left and right, the viewing angle dependency, which was high in the left and right direction, can be reduced, and display with a wide viewing angle can be realized. Further, in the vertically aligned ECB cell, by dividing it vertically and horizontally, a wide viewing angle is realized, non-uniform disclination which is different for each pixel is prevented from appearing, the roughness of the screen is eliminated, and the display quality is improved. Improved. Further, since the pretilt angle is not necessary, the rubbing process of the alignment film is reduced, the manufacturing cost is reduced, and the static electricity generated during the rubbing is eliminated, and the electrostatic breakdown of the TFT is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is a plan view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a plan view of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 8 is a plan view of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 10 is a plan view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 12 is a plan view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 13 is a sectional view of a liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 14 is a plan view of a liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 15 is a sectional view of a liquid crystal display device according to an eighth embodiment of the present invention.

FIG. 16 is a plan view of a liquid crystal display device according to an eighth embodiment of the present invention.

FIG. 17 is a sectional view of a liquid crystal display device according to a ninth embodiment of the present invention.

FIG. 18 is a plan view of a liquid crystal display device according to a ninth embodiment of the present invention.

FIG. 19 is a sectional view of a liquid crystal display device according to a tenth embodiment of the present invention.

FIG. 20 is a plan view of a liquid crystal display device according to a tenth embodiment of the present invention.

FIG. 21 is a plan view of a matrix type liquid crystal display device.

FIG. 22 is a plan view of an active matrix type liquid crystal display device using TFTs.

FIG. 23 is a cross-sectional view of a conventional TN type liquid crystal display device.

FIG. 24 is a perspective view of a conventional TN type liquid crystal display device.

FIG. 25 is a cross-sectional view of a conventional ECB type liquid crystal display device.

FIG. 26 is a diagram illustrating a problem of a conventional TN type liquid crystal display device.

FIG. 27 is a diagram illustrating a problem of a conventional ECB type liquid crystal display device.

[Explanation of symbols]

10, 20, 100, 110 Transparent substrate 11, 21, 101, 111 Transparent electrode 12, 15, 22, 102, 105, 112 Orientation control slice 13, 14, 16, 23, 25, 103, 104, 10
6,113,115 Alignment control inclined part 17,24,107,114 Alignment control window 30,120 Liquid crystal layer 31,121 Liquid crystal director 40,50,130,140 Alignment film U, D, L, R Display zone X Scan Electrode Y Data electrode G Gate line D Drain line P Display electrode

Claims (4)

[Claims] 1. Two substrates, each having a transparent electrode on the opposite surface side, are attached to each other with a liquid crystal layer sandwiched therebetween, and display pixels formed at opposite portions of these electrodes are arranged in a matrix. In the liquid crystal display device, an alignment control sloped portion formed by partially bulging or denting a contact surface with the liquid crystal layer is provided in the periphery or / and the region of the display pixel of at least one of the electrodes. A liquid crystal display device in which the alignment of the liquid crystal is controlled by the alignment control tilting portion. 2. The alignment control sloped portion is formed by partially elevating the electrode by an alignment control slice provided below the electrode. Liquid crystal display device. 3. The alignment control inclination part is provided in the area of the display pixel, divides the display pixel into a plurality of parts, and makes the liquid crystal alignment of each part of the divided display pixel different. The liquid crystal display device according to claim 1, wherein: 4. An alignment control window formed by the absence of an electrode is provided in at least one region of the display pixel of at least one of the electrodes, and the alignment of the liquid crystal controlled by the alignment control tilting portion is further controlled. The liquid crystal display device according to claim 1, wherein: