JP3132964B2 - Matrix type liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type liquid crystal display device.

[0002]

2. Description of the Related Art As a matrix type liquid crystal display device, for example, as shown in FIG. 22, there is a twisted nematic type liquid crystal display device (hereinafter referred to as TN-LCD) which is driven actively. This TN-LCD has two polarizers 1, 2
It has a liquid crystal cell 3 arranged between them. Liquid crystal cell 3
Is provided with a lower substrate 4 and an upper substrate 5 composed of two glass substrates and the like arranged facing each other, and a liquid crystal 6 and the like interposed therebetween. The liquid crystal 6 is composed of a twisted nematic liquid crystal twisted continuously by 90 °. Pixel electrodes 7 are arranged in a matrix on the upper surface of the lower substrate 4, and a lower alignment film 8 is provided on the upper surface. Although not shown, a plurality of scanning lines (gate lines) and a plurality of signal lines (drain lines) 9 are provided on the upper surface of the lower substrate 4 so as to intersect with each other. Is provided with a thin film transistor. The thin film transistor is a switching element, and connects the pixel electrode 7 with the scanning line and the signal line 9. A common electrode (counter electrode) 10 is provided on the lower surface of the upper substrate 4, and an upper alignment film 11 is provided on the lower surface.

When a scanning signal is input to a scanning line in a certain row and all the thin film transistors connected to the scanning line are turned on, a voltage signal corresponding to image data is applied to a signal line 9 in a certain column. When input, a voltage is applied to the pixel electrode 7 from the signal line 9 via the thin-film transistor in the ON state, and a voltage is applied to the liquid crystal 6 between the pixel electrode 7 to which the voltage is applied and the common electrode 10. This changes the orientation of the liquid crystal molecules in that portion, and the optical change accompanying this change is visualized by the polarizers 1 and 2, and a desired display, for example, a black and white display is performed.

[0004] In such a TN-LCD, particularly when the number of pixel electrodes 7 is increased to enable high-definition display, a significant problem is that display quality is greatly reduced due to occurrence of disclination. It has become. That is, when a voltage of about 6 V is applied to the pixel electrode 7 when the TN-LCD is of the normally white mode, for example, the left side of the dotted line 12a in FIG. The normal display portion is formed by the no-multi tilt domain area 12b having the same tilt direction as the reverse tilt domain area 12 having the tilt direction opposite to the pre-tilt direction on the right side.
An abnormal display part that causes light leakage due to c and causes white spots,
A dotted line indicated by reference numeral 12a therebetween is a disclination line. FIG. 23 is a plan view of one pixel unit 12 in this case. In FIG. 23, a region indicated by hatching is an abnormal display unit in which light leakage occurs in the reverse tilt domain region 12c to cause white spots. Thus, the pixel portion 12
When a white spot occurs in a part of the TN-LCD, the contrast of the entire display portion of the TN-LCD is significantly reduced, and the display quality is significantly reduced.

The position where such disclination occurs will be described. The pretilt direction (the lower alignment film 8 side and the upper direction of the liquid crystal 6) is determined by the respective alignment directions (rubbing directions) of the lower alignment film 8 and the upper alignment film 11. It is generated at a position where the direction of the horizontal electric field generated between the pixel electrode 7 and the scanning line and the signal line 9 is orthogonal to the direction of inclination of the long axis of the liquid crystal molecules at both interfaces on the alignment film 11 side. The reason is that the director (unit vector in the direction in which the long axis of the liquid crystal molecules is preferentially oriented) of the liquid crystal 6 having the positive dielectric anisotropy Δε is oriented along the local electric field direction, and thus the pretilt This is because the director is oriented at opposite tilt angles on the left and right sides of the position where the direction is perpendicular to the direction of the lateral electric field.

Such disclination is likely to occur in a high-definition pixel having a small pixel pitch, and is likely to occur in an alignment film having a small pretilt angle at a liquid crystal interface. In the case of high-temperature operation and room-temperature operation, the former is more likely to occur. This is likely to occur because the pretilt angle is small, and is likely to occur when a lateral electric field is strongly generated. In particular, as the pixel pitch decreases, the relative area ratio of the normal display section 12b to the pixel section 12 decreases, so that the decrease in contrast becomes more severe. When the pretilt angle is small, reverse tilt is likely to occur, and the position where the pretilt direction and the direction of the lateral electric field are orthogonal to each other, that is, the position where disclination occurs, moves inside the pixel section 12. Therefore, disclination is more likely to occur in a TN-LCD that requires high definition and high-temperature operation, such as when mounted on a vehicle such as an automobile or used in a projector, and as a method for improving this, Conventionally, light leakage due to disclination has been reduced by providing a light shielding film in accordance with the position where disclination occurs.

[0007]

However, in the conventional method of providing a light-shielding film, each opening edge of the opening of the light-shielding film is moved from the nearest scanning line and signal line 9 to the maximum penetration distance of disclination (for example, In addition, since the apertures are set at positions equidistant from each other by an interval (about twice the cell gap) between the alignment films 8 and 11, there is a problem that the aperture ratio is significantly reduced. An object of the present invention is to provide a matrix type liquid crystal display device capable of reducing light leakage due to disclination and increasing the aperture ratio as much as possible.

[0008]

According to the present invention, a plurality of scanning lines and a plurality of signal lines are formed so as to intersect, and a pixel electrode is formed between the adjacent scanning lines and the adjacent signal lines. A switching element for connecting the pixel electrode to the scanning line and the signal line corresponding thereto is formed, and a first substrate having a first alignment film formed on the pixel electrode is opposed to the pixel electrode. A second substrate on which a counter electrode is formed, and a second alignment film oriented on the counter electrode in a direction substantially perpendicular to the first alignment film; and the first and second alignment films In a matrix type liquid crystal display device having a liquid crystal interposed therebetween, the edge of the pixel electrode extends along three adjacent sides including the edge of the pixel electrode on the side where light leakage due to disclination is maximized. Area outside the pixel electrode and outside the side of the pixel electrode The three sides or <br/> Ranaru auxiliary capacitor electrode having a region located, arranged to face each other through the pixel electrode and the insulating film on the first substrate, and adjacent the storage capacitor electrode of the three sides, the ends of one side of the pixel electrode side of the light leakage is relatively large side by disclination, than the end of the pixel electrode side of one side of the relatively small side 0 .4d (d is the first alignment film and the second alignment film)
(The length between the film and the film) .

[0009]

According to the present invention, the auxiliary capacitance electrode is provided along three adjacent sides including the side of the pixel electrode on the side where the light leakage due to disclination is maximized .
The side where light leakage due to disclination is relatively large
Of one side of the pixel electrode side to the relatively smaller side.
0.4 d or more than the edge of one side on the pixel electrode side.
Since it is arranged inside the elementary electrodes, light leakage due to disclination can be reduced, and the aperture ratio can be made as large as possible.

[0010]

1 and 2 show a main part of a matrix type liquid crystal display device according to an embodiment of the present invention. 1. However, FIG. 1 is a plan view showing a state where the lower alignment film 41 is omitted from the lower substrate 24 side in FIG. This matrix type liquid crystal display device is a transmission type twisted nematic type liquid crystal display device (hereinafter, referred to as a TN-type) which is actively driven.
And a liquid crystal cell 23 disposed between the two polarizers 21 and 22. The liquid crystal cell 23
It has a lower substrate 24 and an upper substrate 25 made of two glass substrates and the like arranged facing each other, and a liquid crystal 26 interposed between them. The liquid crystal 26 is made of a twisted nematic liquid crystal twisted continuously by 90 °.

On the upper surface of the lower substrate 24, a plurality of scanning lines (gate lines) 31 and a plurality of signal lines (drain lines) 3
In the vicinity of each intersection, a thin film transistor 33 as a switching element, a pixel electrode 34, and a shield type auxiliary capacitance electrode 35 are provided. That is, the scanning line 31 including the gate electrode 36 is formed at a predetermined position on the upper surface of the lower substrate 24, the auxiliary capacitance electrode 35 is formed at another predetermined position, and the gate insulating film 37 is formed over the entire upper surface. Is formed. A semiconductor thin film 38 made of amorphous silicon, polysilicon or the like is formed at a predetermined location on the upper surface of the gate insulating film 37. A source electrode 39 and a drain electrode 40 are formed on and near each upper surface of the upper and lower ends of the semiconductor thin film 38, and a signal line 32 is formed simultaneously with the formation of these electrodes 39 and 40. A transparent pixel electrode 34 is formed at a predetermined location on the upper surface of the gate insulating film 37 so as to be connected to the source electrode 39. The lower alignment film 41 is formed on the entire upper surface.

On the other hand, a light-shielding film (black mask) 42 is formed at a predetermined position on the lower surface of the upper substrate 25, and red (R) and green (G) are formed in other portions, that is, in the respective openings 42a of the light-shielding film 42. , Blue (B) color filters 43 are formed. A common electrode (counter electrode) 44 is formed on the lower surface of the color filter 43 and the light shielding film 42, and an upper alignment film 45 is formed on the lower surface of the common electrode 44. Note that the one-dot line in FIG. 1 indicates the opening edge of the opening 42 a of the light shielding film 42.

Here, the pixel electrode 34, the auxiliary capacitance electrode 35
The positional relationship between the openings 42a of the light shielding film 42 will be described. The auxiliary capacitance electrode 35 is provided at a position corresponding to the upper side of the pixel electrode 34 in parallel with the scanning line 31, and is drawn out from the common linear portion 35 a along the left side of the pixel electrode 34. Left drawer 35b
And a right extraction portion 35c extending from the common linear portion 35a along the right side of the pixel electrode 34. The common linear portion 35a is disposed inside the upper side of the pixel electrode 34, and entirely overlaps with the upper side of the pixel electrode 34. The right side of the left extraction portion 35b is overlapped with the left side of the pixel electrode 34. The left side portion of the right extraction portion 35c is overlapped with the right side portion of the pixel electrode 34. A portion where the auxiliary capacitance electrode 35 and the pixel electrode 34 overlap each other forms an auxiliary capacitance portion. The upper opening edge of the opening 42 a of the light-shielding film 42 is arranged inside the upper side of the pixel electrode 34 and inside the common linear portion 35 a of the auxiliary capacitance electrode 35. Opening 4 of light shielding film 42
The opening edge of the left side of 2a is disposed inside the left side of the pixel electrode 34 and outside the left extraction portion 35b of the auxiliary capacitance electrode 35. The opening edge of the right side of the opening 42 a of the light-shielding film 42 is arranged inside the right side of the pixel electrode 34 and outside the right extraction portion 35 c of the auxiliary capacitance electrode 35. The lower opening edge of the opening 42 a of the light-shielding film 42 is arranged inside the lower edge of the pixel electrode 34.

Next, the specific positional relationship between the pixel electrode 34 and the opening 42a of the light-shielding film 42 will be described. First, the relationship between the alignment direction of both alignment films 41 and 45 and the position where disclination occurs is described. Will be described. First, FIG.
FIG. 1 shows a schematic plan view of one pixel electrode 34 and its surrounding scanning lines 31 and signal lines 32. In this case, the width of the gap between the pixel electrode 34 and the scanning line 31 and the signal line 32 (hereinafter simply referred to as the gap) is uniformly L. In addition, as shown by a dotted arrow in FIG. 3, the orientation direction of the lower alignment film 41 is set to an upper left diagonal direction, and as shown by a solid arrow in FIG. And FIG. 4 is a schematic sectional view taken along the line ZZ in FIG. In this case, the distance (cell gap) between the alignment films 41 and 45 was d = 5 μm, the width L of the gap was d, and the pretilt angle θe was 3 °.

Then, + 6V is applied to the pixel electrode 34, -6V is applied to the signal line 32 on the right side of the pixel electrode 34, and 0V is applied to the common electrode 44 and the auxiliary capacitance electrode 35, respectively, and the orientation vector and the equipotential curve of the liquid crystal 26 are examined. As shown in FIG.
Are obtained, and the orientation vector of the liquid crystal 26 and Y
When the value (Y value transmittance curve) was examined, the result shown in FIG. 5B was obtained. Referring to FIG. 5A, electric lines of force are generated in a direction perpendicular to the potential curve, run concentrically with respect to the center of the gap, and the electric lines of force of the horizontal electric field from the pixel electrode 34 toward the signal line 31 are formed. It can be seen that reverse tilt occurs at a place where the tilt direction due to the alignment force of both alignment films 41 and 45 is unnatural, that is, at the left side of the gap, and disclination occurs at the left side of the gap. On the other hand, FIG.
Referring to (B), a peak of light leakage due to disclination occurs on the left side of the gap, and the penetration distance of light leakage on the peak side is about 0.5 d, and the Y value at the peak point is 12
On the other hand, it can be seen that the penetration distance of light leakage on the opposite side of the peak is about 0.3 d and the Y value at the signal line end is about 10. However, the penetration distance of the light leakage was the distance Δx / d between the point where the Y value of the light leakage became 10 times the brightness of a completely dark state and the end of the pixel electrode 34.

Next, the orientation state shown in FIG.
FIG. 6 shows the orientation state when rotated by 5 °. Accordingly, in this case, the orientation direction of the lower alignment film 41 becomes the upward direction as shown by the dotted arrow in FIG. 6, and the alignment direction of the upper alignment film 45 becomes the left direction as shown by the solid arrow in FIG. Direction. Then, when the other conditions were the same as those in the case of the orientation state shown in FIG. 3, the results shown in FIGS. 7A and 7B were obtained. In this case, in particular, FIG.
Referring to (B), a peak of light leakage due to disclination occurs on the right side of the gap.
On the other hand, it can be seen that the Y value is about 0 when the penetration distance of light leakage on the opposite side of the peak is about 0.3 d.

Next, the orientation state shown in FIG.
FIG. 8 shows the orientation state when rotated by 5 °. Therefore, in this case, the orientation direction of the lower alignment film 41 is obliquely upward to the right, as indicated by the dotted arrow in FIG. 8, and the orientation direction of the upper alignment film 45, as indicated by the solid arrow in FIG. Is the diagonally upper left direction. Then, the other conditions were the same as in the case of the orientation state shown in FIG.
The results shown in (A) and (B) were obtained. In this case, especially when looking at FIG. 9B, a peak of light leakage due to disclination occurs on the right side of the gap, and the penetration distance of the light leakage on this peak side is about 0.8 d, and the signal line The Y value at the end is about 28, while the penetration distance of light leakage on the opposite side of the peak is about 0.6 d and the Y value at the pixel electrode end is about 28 d.
It turns out that it is about.

Next, the orientation state shown in FIG.
FIG. 10 shows the orientation state when rotated by 5 °. Therefore, in this case, the orientation of the lower alignment film 41 is rightward as shown by the dotted arrow in FIG. 10, and the orientation of the upper alignment film 45 is upward as shown by the solid arrow in FIG. Direction. Then, when the other conditions were the same as those in the case of the orientation state shown in FIG. 3, the results shown in FIGS. 11A and 11B were obtained. In this case, especially when looking at FIG. 11B, a peak of light leakage due to disclination occurs on the right side of the gap, and the light leakage penetration distance on this peak side is about 0.7 d, and the peak point is reached. It can be seen that the Y value at the end of the pixel electrode is about 8, while the penetration distance of light leakage on the side opposite to the peak is about 0.5d, and the Y value at the pixel electrode end is about 5.

From the above, the relationship between the alignment directions of the alignment films 41 and 45 and the position where the disclination occurs is as shown in FIG. 12 between the alignment state shown in FIG. 3 and the alignment state shown in FIG. 13 (A) and FIG. 13 (A). First, the case of the orientation state shown in FIG. 3 will be described. As shown in FIG. 5B, the permeation distance of light leakage on the peak side is about 0.5 d, and the Y value at the peak point is about 1 2
And the penetration distance of light leakage on the opposite side of the peak is 0.3 d
Since the Y value at the end of the signal line is about 10 in FIG.
As shown in (A), light leakage of about Y value 12 occurs in a region about 0.5 d inward from the right side of the pixel electrode 34, and about 0.3 d inward from the left side of the pixel electrode 34. Light leakage with a Y value of about 10 occurs in the region. On the other hand, when the orientation state shown in FIG. 3 is rotated clockwise by 90 °, the orientation state shown in FIG. 8 is obtained. Therefore, the disclination occurrence position in the horizontal direction in the orientation state shown in FIG. 8 can be regarded as the disclination occurrence position in the vertical direction in the orientation state shown in FIG. Then, as shown in FIG. 9B, the penetration distance of the light leakage on the peak side is about 0.8d, the Y value at the signal end is about 28, and the penetration distance of the light leakage on the opposite side of the peak is About 0.6d, Y at the pixel electrode end
Since the value is about 28, as shown in FIG.
Light leakage of about Y value 28 occurs in a region about 0.8 d inward from the lower side of the pixel electrode 34, and light leakage of about 28 d in about 0.6 d inward from the upper side of the pixel electrode 34. Leaks occur.

Then, in the case of the orientation state shown in FIG.
Since this corresponds to the case where the orientation state shown in FIG. 3 is rotated clockwise by 90 °, it becomes as shown in FIG. Further, in the orientation state when the orientation state shown in FIG. 8 is rotated clockwise by 90 °, the orientation state becomes as shown in FIG.
FIG. 12D shows the orientation state when rotated further by 90 ° clockwise.

Next, the case of the orientation state shown in FIG. 6 will be described. As shown in FIG. 7B, the permeation distance of the light leakage on the peak side is about 0.7 d, and the Y value at the peak point is 25.
And the penetration distance of light leakage on the opposite side of the peak is 0.1.
Since the Y value is about 0 at about 3d, as shown in FIG. 13A, light leakage of about 25 Y values occurs in a region about 0.7d inward from the left side of the pixel electrode 34, and Y is located in a region about 0.3d inward from the right side of the pixel electrode 34.
Light leakage of about 0 occurs. On the other hand, when the orientation state shown in FIG. 6 is rotated clockwise by 90 °, the orientation state shown in FIG. 10 is obtained. Therefore, the position of occurrence of disclination in the horizontal direction in the orientation state shown in FIG. 10 can be regarded as the position of occurrence of disclination in the vertical direction in the orientation state shown in FIG. Then, as shown in FIG. 11 (B), the light leakage penetration distance on the peak side is about 0.7d, the Y value at the peak point is about 8, and the light leakage penetration distance on the opposite side of the peak is When about 0.5d, the Y value at the pixel electrode end is 5
As shown in FIG. 13A, the Y value of 8 is set in a region about 0.7d inward from the lower side of the pixel electrode 34.
A light leak of about 5 occurs, and a light leak of about Y value 5 occurs in a region about 0.5 d inward from the upper side of the pixel electrode 34.

The orientation state shown in FIG. 10 corresponds to a case where the orientation state shown in FIG. 6 is rotated clockwise by 90 °, and is as shown in FIG. 13B.
FIG. 13C shows an orientation state when the orientation state shown in FIG. 10 is rotated 90 ° clockwise, and FIG. 13C shows an orientation state when the orientation state is further rotated clockwise 90 °. 13 (D).

As described above, the disclination positions in the eight orientation states shown in FIGS. 12 and 13 are different from each other. Thus, for example, in the case of the orientation state shown in FIG. 12A, the light shielding film 42 shown in FIGS.
The distance between the left edge of the opening 42a of the opening 42a and the left side of the pixel electrode 34 is 0.3d, the distance between the right edge of the opening 42a of the light shielding film 42 and the right side of the pixel electrode 34 is 0.5d,
The lower opening edge of the opening 42a of the light shielding film 42 and the pixel electrode 34
Of the light shielding film 42 is set to 0.8d.
2a is set to 0.
With 6d, light leakage due to disclination can be reduced, and the aperture ratio can be made as large as possible. By the way, FIG.
1D, the difference between the case where the penetration distance of light leakage is the maximum and the case where the penetration distance of the light leakage is the minimum is 0.5 d.
In the orientation states shown in FIGS. 3 (A) to 3 (D), the difference between the case where the penetration distance of the light leakage is the maximum and the case where the penetration distance is the minimum is 0.4d. It is desirable to do.

In the plan views of the light leakage due to the disclination shown in FIGS. 12 and 13, the position of the opening edge of the light shielding film 42 is not necessarily the pixel electrode 3.
It is not necessary that each side of 4 be different. FIG.
When observing (A) to (D), the penetration distance and the Y value of the light leakage appearing on the opposite side of the pixel electrode 34 are close to each other, so that the opening edge of the light shielding film 42 is set to the same position on each opposite side. You can also. Further, particularly, the position of the opening edge on the opposite side where the Y value is larger is set to different values, for example, about 0.6d and 0.8d, and the position of the opening edge on the opposite side where the Y value is smaller is the same value. For example, it may be about 0.3d to 0.5d. Also, when observing FIGS. 13 (A) to 13 (D), the penetration distance of light leakage is large on two adjacent sides, and the remaining 2
Although the value is small on the side, the Y value is large only on one side and the remaining 3
Since the side edges are small, the positions of the opening edges on the adjacent two sides where the penetration distance of light leakage is large are the same, and the positions of the opening edges on the remaining two sides are smaller than that. , The position of the opening edge on one side where both the penetration distance and the Y value are large may be increased, and the positions of the opening edges on the remaining sides may be smaller and the same position.

By the way, even when the alignment direction of the alignment films 41 and 45 is oblique to the scanning line 31 or in a direction parallel or orthogonal to the scanning line 31, the voltage supplied to the scanning line 31 is actually driven. Is higher than the voltage supplied to the signal line 32, the potential difference between the scanning line 31 and the pixel electrode 34 is considerably larger than the potential difference between the signal line 32 and the pixel electrode 34. Therefore, in order to further reduce the light leakage due to the disclination, it is desirable that the side where the light leakage due to the disclination is small is on the scanning line 31 side and the side where the light leakage is large is on the signal line 32 side. For this reason, in the case of the four alignment states shown in FIG. 12, the alignment states shown in (B) and (D) are more preferable than the alignment states shown in (A) and (C). In the case of the four alignment states shown in FIG. 13, the alignment states shown in FIGS. 13A and 13C are more preferable than the alignment states shown in FIGS. 13B and 13D.

On the other hand, as shown in FIG. 1, an auxiliary capacitance electrode 35 (left extraction portion 35b and right extraction portion 35c) between the pixel electrode 34 and the signal line 32 is set to the ground potential or the same potential as the common electrode 44. Is present, the existing auxiliary capacitance electrode 35 acts as a shield electrode for reducing the lateral electric field in that portion. The same applies to the case where the auxiliary capacitance electrode 35 exists between the pixel electrode 34 and the scanning line 31. Therefore, as described above, the orientation states shown in FIGS. 12B and 12D and FIGS. 13A and 13C are desirable. However, in these arrangement states, light leakage due to disclination may occur. Along the adjacent two or three sides including the side of the pixel electrode 34 which is the largest, there is a region overlapping the side of the pixel electrode 34 and a region located outside the side of the pixel electrode 34. In this arrangement, light leakage due to disclination can be further reduced, and the aperture ratio can be further increased.

For this reason, when the orientation direction of the lower alignment film 41 is obliquely upward to the right as shown by the dotted arrow in FIG. 12B, as shown in FIG. It is preferable that the electrodes 35 are arranged on the left side, right side, and lower side of the pixel electrode 34. When the alignment direction of the lower alignment film 41 is obliquely downward to the left as shown by the dotted arrow in FIG. 12D, the auxiliary capacitance electrode 35 is connected to the left side of the pixel electrode 34 as shown in FIG. , On the right side and the upper side. As shown by the dotted arrow in FIG. 13A, when the orientation direction of the lower orientation film 41 is the upward direction, as shown in FIG.
Are preferably arranged on the left side and the lower side of the pixel electrode 34. As shown by a dotted arrow in FIG.
When the orientation direction of the lower orientation film 41 is downward, FIG.
As shown in FIG. 7, it is preferable that the auxiliary capacitance electrode 35 be disposed on the right side and the upper side of the pixel electrode 34.

The dependence on the disclination was examined by changing the width L of the gap.
The results shown in (A) and (B) were obtained. Figure 1
8A shows the relationship between the width L of the gap and the penetration distance of light leakage on the peak side, and FIG. 8B shows the relationship between the width L of the gap and the Y value at the peak-side electrode end. In these figures, the solid line shows the case of the orientation state shown in FIG. 3, the dotted line shows the case of the orientation state shown in FIG. 6, the dashed line shows the case of the orientation state shown in FIG. 11 shows a case of the orientation state shown in FIG. 18 (A), the greater the width L of the gap, the smaller the penetration distance of light leakage, and
It can be seen that there is almost no change if d or more. The reason is that if the distance between the pixel electrode 34 having the opposite sign and the signal line 32 increases, the magnitude of the horizontal electric field naturally decreases. Therefore, if the width L of the gap is too large, the area of the pixel electrode 34 becomes small. Therefore, it is preferable that the width L is as small as about 1 or more.

Next, the dependency on disclination was examined by changing the pretilt angle θe.
9 and the results shown in FIG. 20 were obtained. Among them, FIG.
(A) shows the relationship between the pretilt angle θe and the Y value of the peak, and (B) shows the relationship between the pretilt angle θe and the penetration distance of light leakage on the peak side. FIG. 20A shows the relationship between the pretilt angle θe and the Y value at the electrode end opposite to the peak,
(B) shows the relationship between the pretilt angle θe and the penetration distance of light leakage on the side opposite to the peak. In these figures, the solid line shows the case of the orientation state shown in FIG. 3, the dotted line shows the case of the orientation state shown in FIG. 6, the dashed line shows the case of the orientation state shown in FIG. 11 shows a case of the orientation state shown in FIG. 19B, the penetration distance of light leakage on the peak side becomes shorter as the pretilt angle θe becomes larger. In particular, it can be understood that light leakage due to disclination can be improved by using a high pretilt alignment film having a pretilt angle θe of 5 ° or more. However, the present invention is not limited to a high pretilt orientation, and is effective even in a normal case where the pretilt angle is about 3 °.

FIG. 21 shows a main part of a matrix type liquid crystal display device according to another embodiment of the present invention. In this figure, the same parts as those in FIG. In this embodiment, although not shown, a light-shielding film is provided only on the lower surface of the upper substrate 25 in a portion corresponding to the thin film transistor,
In other portions, only the color filter 43 is provided. Instead, the auxiliary capacitance electrode 35 also serves as a light shielding film. Then, as in the case shown in FIG. 2, for example, the left edge of the opening 35a of the auxiliary capacitance electrode 35 and the pixel electrode 34
If the distance between the right side of the opening 35a of the auxiliary capacitance electrode 35 and the right side of the pixel electrode 34 is 0.5d, the light leakage due to disclination can be reduced. It is possible to increase the aperture ratio as much as possible. Also, the alignment film 4
13 (B), (D) and FIG.
It is desirable that the alignment states shown in FIGS. 14A and 14C are respectively set, and the arrangement state of the auxiliary capacitance electrodes 35 is almost the same as the cases shown in FIGS.

When a light-shielding film for shielding the thin film transistor is provided on the lower substrate 24, it is not necessary to provide the upper substrate 25 with a light-shielding film. In addition, as a switching element,
Instead of the thin film transistor, a non-linear element such as MIM (metal-insulating film-metal) may be used. The lower alignment film 4
The orientation directions of 1 and the upper alignment film 45 are not limited to those that intersect at an angle of 90 °, but can be applied to those that intersect at an angle of 90 ° to 130 °. Further, the present invention is not limited to a color display or a transmission type, but a black and white display or a reflection type T
It can also be applied to N-LCDs.

[0032]

According to the present invention, the auxiliary capacitance electrode is provided along three adjacent sides including the side of the pixel electrode on the side where light leakage due to disclination is maximized.
Light leakage due to electrode disclination is relatively large
The edge of the pixel electrode side of one side on the threshold side is relatively small.
0.4d or more than the pixel electrode side end of one side
Since it is arranged inside the pixel electrode, light leakage due to disclination can be reduced, and the aperture ratio can be made as large as possible.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a matrix type liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG. 1;

FIG. 3 is a schematic plan view showing one pixel electrode and portions of a scanning line and a signal line around the pixel electrode.

FIG. 4 is a schematic sectional view taken along the line ZZ in FIG. 3;

5A is a diagram in which an alignment vector diagram of the liquid crystal in the alignment state shown in FIG. 3 and an equipotential curve are superimposed, and FIG.
FIG. 3 is a diagram in which the orientation vector diagram of the liquid crystal and the Y value in the same orientation state are superimposed.

FIG. 6 is a schematic plan view showing an orientation state when the orientation state shown in FIG. 3 is rotated clockwise by 45 °.

7A is a diagram in which an orientation vector diagram of the liquid crystal in the orientation state shown in FIG. 6 and an equipotential curve are superimposed, and FIG.
FIG. 3 is a diagram in which the orientation vector diagram of the liquid crystal and the Y value in the same orientation state are superimposed.

FIG. 8 is a schematic plan view showing an alignment state when the alignment state shown in FIG. 6 is rotated clockwise by 45 °.

9A is a diagram in which an orientation vector diagram of the liquid crystal in the orientation state shown in FIG. 8 and an equipotential curve are superimposed, and FIG.
FIG. 3 is a diagram in which the orientation vector diagram of the liquid crystal and the Y value in the same orientation state are superimposed.

FIG. 10 is a schematic plan view showing an orientation state when the orientation state shown in FIG. 8 is rotated clockwise by 45 °.

11A is a diagram in which an alignment vector diagram of a liquid crystal in the alignment state shown in FIG. 10 and an equipotential curve are superimposed, FIG.
(B) shows the orientation vector diagram of the liquid crystal in the same orientation state and Y
The figure which superimposed the value.

12A is a diagram illustrating a disclination generation position in the orientation state illustrated in FIG. 3;
(B)-(D) is a figure shown for demonstrating the disclination generation position in each orientation state at the time of rotating 90 degrees clockwise from the orientation state shown in (A), respectively.

13A is a view for explaining a disclination occurrence position in the orientation state shown in FIG. 6, FIG.
(B)-(D) is a figure shown for demonstrating the disclination generation position in each orientation state at the time of rotating 90 degrees clockwise from the orientation state shown in (A), respectively.

FIG. 14 is a diagram showing an arrangement state of storage capacitor electrodes in the orientation state shown in FIG.

FIG. 15 is a diagram showing an arrangement state of auxiliary capacitance electrodes in the orientation state shown in FIG.

FIG. 16 is a diagram showing an arrangement state of storage capacitor electrodes in the orientation state shown in FIG.

FIG. 17 is a view showing an arrangement state of storage capacitor electrodes in the orientation state shown in FIG.

18A is a diagram showing the relationship between the width L of the gap and the penetration distance of light leakage at the peak side, and FIG. 18B is a diagram showing the relationship between the width L of the gap and the Y value at the peak-side electrode end; The figure which shows a relationship.

19A is a diagram illustrating a relationship between a pretilt angle θe and a Y value of a peak, and FIG. 19B is a diagram illustrating a relationship between a pretilt angle θe and a penetration distance of light leakage on a peak side.

FIG. 20A is a diagram showing the relationship between the pretilt angle θe and the Y value at the electrode end on the opposite side of the peak, and FIG. 20B is a diagram showing the relationship between the pretilt angle θe and the penetration distance of light leakage on the opposite side of the peak. FIG.

FIG. 21 is a sectional view showing a main part of a matrix type liquid crystal display device according to another embodiment of the present invention.

FIG. 22 is a cross-sectional view of a part of a conventional matrix type liquid crystal display device.

FIG. 23 is a plan view showing a state where disclination has occurred in one pixel portion.

[Explanation of symbols]

 Reference Signs List 24 lower substrate 25 upper substrate 26 liquid crystal 31 scan line 32 signal line 33 thin film transistor 34 pixel electrode 35 auxiliary capacitance electrode 41 lower alignment film 42 light shielding film 42a opening 44 common electrode (opposite electrode) 45 upper alignment film

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1337 G02F 1/136

Claims (6)

(57) [Claims] 1. A plurality of scanning lines and a plurality of signal lines are formed to intersect with each other, and a pixel electrode is formed between the adjacent scanning line and the adjacent signal line, and the pixel electrode and the corresponding pixel electrode are formed. A switching element for connecting a scanning line and the signal line is formed, a first substrate on which a first alignment film is formed on the pixel electrode, and a counter electrode facing the pixel electrode are formed. A second alignment film formed on an electrode and having a second alignment film oriented in a direction substantially orthogonal to the first alignment film;
And a liquid crystal interposed between the first and second alignment films, comprising a side of the pixel electrode on a side where light leakage due to disclination is maximized. Along the three adjacent sides , an auxiliary capacitance electrode having three sides having a region overlapping with the side of the pixel electrode and a region located outside the side of the pixel electrode is provided on the first substrate by the pixel. An end on the pixel electrode side of one of three adjacent sides of the storage capacitor electrode, the side on which light leakage due to disclination is relatively large among the three sides adjacent to the storage capacitor electrode; Is smaller than the edge on the pixel electrode side of one side on a relatively small side by 0.4 d (d
Is a length between the first alignment film and the second alignment film) or more inside the pixel electrode. 2. An obliquely rightward upper direction, wherein the orientation direction of the first orientation film is a horizontal direction of a wiring direction of the scanning line.
2. The matrix type liquid crystal display device according to claim 1, wherein the direction is one of a left oblique downward direction, an upward direction, and a downward direction. 3. An alignment direction of the first alignment film is a diagonally upper right direction when a wiring direction of the scanning line is a horizontal direction, and the auxiliary capacitance electrode is a left side and a right side of the pixel electrode. 2. A matrix type liquid crystal display device according to claim 1, wherein said matrix type liquid crystal display device is arranged on a lower side. 4. An alignment direction of the first alignment film is a diagonally lower left direction when a wiring direction of the scanning line is a horizontal direction, and the auxiliary capacitance electrode is a left side and a right side of the pixel electrode. 2. The matrix type liquid crystal display device according to claim 1, wherein said matrix type liquid crystal display device is arranged on an upper side. 5. An alignment direction of the first alignment film is set to an upper direction when a wiring direction of the scanning line is set to a horizontal direction, and the auxiliary capacitance electrode is disposed on a left side and a lower side of the pixel electrode. 2. A matrix type liquid crystal display device according to claim 1, wherein: 6. An alignment direction of the first alignment film is set to a downward direction when a wiring direction of the scanning line is set to a horizontal direction, and the auxiliary capacitance electrode is disposed on a right side and an upper side of the pixel electrode. 2. A matrix type liquid crystal display device according to claim 1, wherein: