JP2001281682A - Active matrix liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress block separation caused by the variation in the capacitance of a signal wiring and a pixel electrode. SOLUTION: Overhang parts 62a and 62b lapping with adjacent source wiring 54 are provided at ends of both side parts of the pixel electrode 62. Then, the length of the both overhangs parts 62a and 62b is made the same. Thereby, the difference in the capacitance between the pixel electrode 62 and the source wiring 54a in one side and the capacitance between the pixel electrode 62 and the source wiring 54b in the other side hardly changes, when a few alignment deviations occur in each interblock in a photolithographic process. Therefore, the block separation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device used for a liquid crystal television, a notebook personal computer or the like.

[0002]

2. Description of the Related Art FIGS. 12 and 13 are a plan view and a sectional view of a general active matrix type liquid crystal display device. The active matrix type liquid crystal display device is schematically constituted by a liquid crystal panel 1, a gate drive circuit 2, a source drive circuit 3, and a backlight 4.

Further, the liquid crystal panel 1 has an active matrix substrate 5, a counter substrate 6, a liquid crystal layer 7 interposed between the substrates 5, 6, and a deflecting plate (shown in FIG. )).

On the active matrix substrate 5, a plurality of scanning wirings (not shown) arranged in parallel, and a plurality of signal wirings arranged in parallel with the scanning wirings through an insulating film 8 at right angles. 9, a thin film transistor (TFT) 10 disposed near each intersection between the scanning wiring and the signal wiring 9, a plurality of pixel electrodes 11 disposed in a region surrounded by the scanning wiring and the signal wiring 9, and the like. Have been.

FIG. 14 is a plan view of one pixel portion of the active matrix substrate 5. Pixel electrode 11
Is formed in the same layer as the signal wiring 9,
It is formed so as not to contact the signal wiring 9 at a predetermined distance. The TFT 10 is a three-terminal device, and the conduction of current between the drain electrode 13 and the source electrode 14 is controlled by a voltage applied to the gate electrode 12. Then, the gate electrode 12 is connected to the adjacent scanning line 15, the source electrode 14 is connected to the adjacent signal line 9, and
The drain electrode 13 is connected to the pixel electrode 11.

On the other hand, each pixel electrode 1 is
A color filter 16 is formed at a position corresponding to 1 in the order of arrangement of red, green, and blue. A black matrix 17 is formed between the color filters 16 and 16 as a light shielding film for preventing light from leaking from between the scanning wiring 15 and the signal wiring 9 and the pixel electrode 11. Further, a counter electrode 18 made of a transparent conductive material is formed on this upper layer. The gate drive circuit 2 and the source drive circuit 3 are connected to the terminals of the scanning wiring 15 and the terminals of the signal wiring 9 arranged around the liquid crystal panel 1, respectively.

Next, a method of driving the active matrix type liquid crystal display device having the above configuration will be described.

In the driving method of the active matrix type liquid crystal display device, when writing the pixel array in the n-th row, the scanning line 1 from the gate drive circuit 2 to the n-th row is used.
An ON signal (a potential at which the TFT 10 is turned on: Vgh) is input to 5n. At this time, an off signal (a potential at which the TFT 10 is turned off: Vgl) is input to the scanning lines other than the scanning line 15n. Therefore, only the TFT 10 in the n-th row is turned on. In this case, a source signal of a voltage to be charged to the pixels in the n-th row (the pixel electrode 11 and the liquid crystal layer 7) is supplied from the source drive circuit 3 to each signal line 9.

When the writing to the array of pixels in the n-th row is completed, an off signal is input to the scanning wiring 15n, while an on signal is input to the scanning wiring 15 (n + 1). By repeating the above operation, all the pixels are charged with an arbitrary voltage value. Since the transmittance of the liquid crystal layer 7 between the pixel electrode 11 and the counter electrode 18 changes depending on the voltage applied between the electrodes 11 and 18, the light from the backlight 4 is adjusted to display an arbitrary image. Is done.

By the way, a pixel electrode is provided on the interlayer insulating film, and the pixel electrode and the signal wiring are formed on different layers.
A structure in which a pixel electrode is overlaid on a signal line has also been proposed.
(JP-A-63-279228). FIG. 15 is a cross-sectional view of one pixel in an active matrix liquid crystal display device having a structure in which the pixel electrode is overlaid on a signal wiring. FIG. 16 is a plan view of the active matrix substrate shown in FIG. In such a configuration, the pixel electrode 21 and the signal line 22 are formed in different layers, and the pixel electrode 21 and the signal line 22 are
And the pixel electrode 21 and the signal wiring 2
2 can be eliminated. Therefore, the area (aperture ratio) of the pixel electrode 21 can be increased, and the power consumption of the active matrix liquid crystal display device can be suppressed. 24 is an active matrix substrate, 25 is a TFT, 26 is a liquid crystal layer, 27 is a counter electrode, 2
Reference numeral 8 denotes a counter substrate, 29 denotes a scanning line, 30 denotes a contact hole, 31 denotes an auxiliary capacitance electrode, and 32 denotes an auxiliary capacitance line.

However, as described above, the pixel electrode 21
In the case where the structure in which is overlapped with the signal wiring 22 is adopted, FIG.
As shown in FIG. 4, the capacitance Csd between the pixel electrode 21 and the signal wiring 22 is increased as compared with the conventional structure in which the pixel electrode 11 is at a predetermined distance from the signal wiring 9. In that case,
With an increase in the capacitance Csd, the potential of the pixel is easily changed by the source signal, and a deterioration in display characteristics called shadowing occurs.

Hereinafter, this mechanism will be described using an equivalent circuit of the active matrix substrate 24 shown in FIG. That is, when the ON signal Vgh is input to the scanning line Gn and the TFT 23 is turned on, the voltage Vs1 of the signal line S1 is charged to the pixel electrode P1.

Next, when the off signal Vgl is input to the scanning line Gn and the TFT 23 is turned off, the signal line S1 is turned off.
Is supplied with a voltage Vs1 'to be written to the pixel electrode P2 of the next stage. In that case, the voltage of the pixel electrode P1 is the capacitance Cs
It changes under the influence of the voltage Vs1 'of the signal wiring S1 via d1. Assuming that the voltage of the pixel electrode P1 at that time is Vp1, Vp1 = Vs1− (Csd1 (Vs1−Vs1 ′) + Csd2 (Vs2−Vs2 ′)) / (Cp + Csd1 + Csd2) (1) Here, Cp is the capacitance of the pixel electrode (Cp = liquid crystal capacitance Clc + auxiliary electrode capacitance Ccs), and Csd1 is the signal line S1.
Csd2 is the capacitance between the signal line S2 and the pixel electrode P2, and Vs1, Vs
2 is the voltage of the signal wirings S1 and S2 when the scanning wiring Gn of the n-th column is in the on state, and Vs1 ′ and Vs2 ′ are the voltages of the scanning wiring G (n + 1) of the (n + 1) -th column. If there is a signal wiring S1,
This is the voltage of S2.

An active matrix type liquid crystal display device
In a gate line inversion drive (1H inversion drive) which is a general driving method, the polarity of a source signal is inverted for each gate line. Here, assuming that the adjacent gradations are the same, Vs = Vs1 = Vs2, Vs ′ = Vs1 ′ = Vs2 ′ (2) Therefore, from equations (1) and (2), Vp1 = Vs− (Csd1 + Csd2) / (Cp + Csd1 + Csd2) · (Vs−Vs ′) (3) Thus, in the 1H inversion drive, the amount of change in pixel potential is proportional to (Csd1 + Csd2). For this reason, shadowing appears remarkably with an increase in the capacitance Csd between the signal line S and the pixel electrode P.

On the other hand, dot inversion driving has been proposed as a driving method for suppressing a change in pixel potential due to the capacitance Csd between the signal line S and the pixel electrode P. In this dot inversion drive, the polarity of the source signal is inverted for each gate line, and a signal of the opposite polarity is also input to the source side for each source line.

In the case of the above-mentioned dot inversion driving, assuming that the adjacent gray scales are the same, Vs = Vs1 = −Vs2, Vs ′ = Vs1 ′ = − Vs2 ′ (4) From (1) and equation (4), Vp1 = Vs− (Csd1−Csd2) / (Cp + Csd1 + Csd2) · (Vs−Vs ′) (5) As described above, in the dot inversion drive, the amount of change in the pixel potential is proportional to the difference between the capacitance Csd1 and the capacitance Csd2. Therefore, the shadowing phenomenon can be greatly suppressed as compared with the case of 1H inversion driving, and the image quality of the liquid crystal display device can be improved. In particular, when the difference between the capacitance Csd1 and the capacitance Csd2 of the pixels adjacent to each other in the direction in which the scanning wiring 29 extends, the shadowing phenomenon can be significantly suppressed.

[0017]

However, the conventional active matrix type liquid crystal display device shown in FIGS. 15 and 16 has the following problems. That is, as described above, in the active matrix type liquid crystal display device having a structure in which the pixel electrode 21 and the signal wiring 22 are overlapped via the interlayer insulating film 23 as shown in FIGS. Thereby, the aperture ratio can be increased and the shadowing phenomenon due to the coupling capacitance Csd between the signal wiring 22 and the pixel electrode 21 can be suppressed.

However, on the other hand, the following new problem occurs. In a general liquid crystal display device, the photolithography process is performed in units of blocks, and thus misalignment occurs between blocks. Thereby, the signal line S and the pixel electrode P
And the capacitance Csd during this period changes.
When the dot inversion drive is adopted, the pixel potential easily changes due to the change in the capacitance Csd, and thus the transmittance changes in units of blocks.

For example, as shown in FIG. 18, consider a case where an alignment deviation dx occurs in the photolithography process of the pixel electrode P. In this case, the amount of overlap of the pixel electrode P with the signal line S1 increases, so that the capacitance Csd1 between the signal line S1 and the pixel electrode P increases, and conversely, the capacitance Csd2 between the signal line S2 and the pixel electrode P. Decreases. FIG.
FIG. 9 shows the relationship between the misalignment dx and the capacitance Csd1 or Csd2 in the photolithography process. As shown in FIG. 19, as the misalignment dx increases, the difference between the capacitances Csd1 and Csd2 increases, and the amount of change in the pixel potential increases.

In a general photolithography process, exposure is performed by dividing the surface of the active matrix substrate into several blocks. For this reason, when the alignment shift occurs, the overlapping width of the signal wiring and the pixel electrode changes between the blocks, and as a result, a transmittance difference occurs between the blocks of the active matrix type liquid crystal display device. FIG. 20 shows the relationship between the alignment shift dx and the transmittance difference ΔT with respect to the block having no alignment shift for the block in which the alignment shift has occurred.

That is, when an active matrix type liquid crystal display having a structure in which the pixel electrode is overlapped with the signal wiring is driven by dot inversion, the amount of change in the pixel potential itself due to the coupling capacitance Csd decreases. Variations between the photo blocks increase. For this reason, the transmittance difference between the blocks becomes large, and a problem called so-called “block division” occurs. And, with the enlargement of the active matrix type liquid crystal display device,
Since the number of blocks in the photolithography process tends to increase more and more, it is desired to suppress the occurrence of block separation due to the coupling capacitance Csd described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide an active matrix type liquid crystal display device which can prevent deterioration in image quality due to coupling capacitance between a signal wiring and a pixel electrode and can suppress block separation due to the variation in coupling capacitance. Is to do.

[0023]

In order to achieve the above object, the present invention provides a plurality of scanning wirings formed on an insulating substrate, a plurality of signal wirings intersecting with the scanning wirings, the scanning wirings and the signal wirings. In an active matrix liquid crystal display device having a plurality of switching elements arranged in a matrix in the vicinity of each intersection with wiring and pixel electrodes arranged in a matrix connected to output terminals of the switching elements, A part of both sides of the electrode covers two signal lines adjacent to the pixel electrode in the width direction.

According to the above configuration, a part of both sides of the pixel electrode along the signal wiring covers the two signal wirings adjacent to the pixel electrode in the width direction. Therefore, the difference between the first capacitance between the pixel electrode and the signal wiring adjacent to one side and the second capacitance between the pixel electrode and the signal wiring adjacent to the other side is determined by the layer Even if there is a misalignment between them, there is no significant change. As a result, block separation that occurs when the photolithography process is performed in block units is suppressed.

In the active matrix type liquid crystal display device according to the present invention, it is preferable that the switching element is covered by the pixel electrode.

According to the above configuration, the pixel electrode can be arranged on the switching element. Therefore,
The pixel electrodes can be arranged in a substantially rectangular shape, and the area of the pixel electrodes increases, thereby reducing power consumption.

Further, in the active matrix type liquid crystal display device according to the present invention, the signal wiring is bent in the vicinity of the first and second pixel electrodes adjacent to each other, and one of the first and second pixel electrodes is bounded by the bent portion as a boundary. It is preferable that the electrode is covered in the width direction by an electrode, and the other is covered in the width direction by the second pixel electrode at the above-mentioned bending.

According to the above configuration, the structure in which the two signal lines adjacent to the pixel electrode are covered in the width direction at a part of both sides of the pixel electrode along the signal line uses a rectangular pixel electrode. Achieved. Therefore, it is easy to form a color filter having substantially the same shape as the pixel electrode disposed on the counter substrate facing the insulating substrate and a black matrix disposed at a position between the image electrodes adjacent to each other on the counter substrate. become.

Further, in the active matrix type liquid crystal display device of the present invention, both side edges along the signal wiring are bent to form overhangs on both sides of the pixel electrodes, and the pixel electrodes are adjacent by the overhangs. It is desirable to cover the signal wiring in the width direction.

According to the above structure, the structure in which the two signal lines adjacent to the pixel electrode are covered in the width direction at a part of both sides along the signal line of the pixel electrode is a linear signal line. Achieved by using Accordingly, the length of the signal wiring can be shortened, and problems such as a delay of a source signal and a disconnection failure of the signal wiring which occur when a large active matrix type liquid crystal display device having a size of 15 inches or more are constructed are reduced.

In the active matrix type liquid crystal display device according to the present invention, it is preferable that the switching element is disposed in the vicinity of two pixel electrodes adjacent to each other.

According to the above configuration, the switching element is arranged near the pixel electrodes adjacent to each other, which is an area to be shielded from light. Therefore, there is no need to arrange a black matrix dedicated to the switching element, and an increase in the area of the black matrix can be prevented, and a large aperture ratio can be obtained.

Further, the active matrix type liquid crystal display device of the present invention is arranged such that the opposing substrate is disposed opposite to the insulating substrate, and the opposing substrate is disposed between the two adjacent pixel electrodes on the opposing substrate. At the same time, one side edge of the side facing the pixel electrode covering the signal wiring is located inside the pixel electrode with respect to the center line of the covered signal wiring, including the center line. On the other hand, it is preferable that the other side edge includes a black matrix that is located at a distance from the side edge of the signal wiring opposite to the pixel electrode at least by an alignment margin between the counter substrate and the insulating substrate.

According to the above configuration, the positions of both side edges of the black matrix arranged on the counter substrate are set in consideration of an alignment margin between the counter substrate and the insulating substrate. Therefore, even if there is a misalignment between the two substrates, light is reliably shielded between the pixel electrodes adjacent to each other, and the block division is further suppressed.

Further, the active matrix type liquid crystal display device of the present invention desirably includes a light-shielding film disposed on the insulating substrate at a position between mutually adjacent pixel electrodes.

Generally, the alignment accuracy between the insulating substrate on which the pixel electrodes are formed and the opposing substrate facing the insulating substrate is about ± 5 μm, whereas the alignment accuracy between the layers on the insulating substrate is small. Accuracy is ± 1μm
It is as follows. According to the configuration, the light-shielding film is disposed at a position between the pixel electrodes adjacent to each other on the insulating substrate. Therefore, the width of the light-shielding film is formed narrower than that of the black matrix arranged on the counter substrate side, and the black matrix is eliminated, thereby improving the aperture ratio.

Further, since the area of the black matrix disposed on the counter substrate side is reduced, the bonding margin between the insulating substrate and the counter substrate is widened.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. <First Embodiment> FIG. 1 is a plan view of an active matrix substrate in an active matrix type liquid crystal display device of the present embodiment. FIG. 2 is a cross-sectional view of the active matrix type liquid crystal display device taken along the line AA ′ of FIG.

The active matrix substrate has the following configuration. That is, in FIGS. 1 and 2, a plurality of gate wirings (scanning wirings) 52 made of metal such as Al and Ta are arranged in parallel on an insulating substrate 51 made of glass as the active matrix substrate.
The thickness of the gate wiring 52 is 2000 to 5000 degrees. Further, Al, Ta is interposed orthogonally to the gate wiring 52 via a gate insulating film 53 made of SiNx or the like.
A plurality of source wirings 54 made of metal such as. The thickness of the gate insulating film 53 is 2000 to 4000 mm.
And the relative dielectric constant is about 3 to 8. In addition, the thickness of the source wiring 54 is 1000 ° to 5000 °.

An amorphous silicon TFT 55 is located near each intersection between the gate wiring 52 and the source wiring 54.
Is arranged. Amorphous silicon TFT 55
Is formed by stacking a gate electrode 56, a gate insulating film 53, an amorphous semiconductor layer 57, an impurity-added semiconductor layer 58, a source electrode 59, and a drain electrode 60. Gate electrode 56 is made of the same material as gate wiring 52. The source electrode 59 and the drain electrode 60 are made of the same material as the source wiring 54. The amorphous semiconductor layer 57 is made of amorphous silicon formed by CVD (Chemical Vapor Deposition), and has a thickness of about 500 to 2000 degrees. The gate electrode 56 is connected to the adjacent gate wiring 52, and the source electrode 59 is connected to the adjacent source wiring 54.

The previous-stage gate wiring 52a overlaps the main-stage pixel electrode 62, and
The drain electrode 60 extends through the gate insulating film 53 to above the overlapping region in a, and the storage capacitor electrode 64 is formed by the end of the drain electrode 60. The interlayer insulating film 61 is made of an organic material or an inorganic material, has a thickness of 1 μm to 4 μm, and has a relative dielectric constant of 2 to 4 μm.
It is about. A contact hole 65 is provided at the position of the auxiliary capacitance electrode 64 in the interlayer insulating film 61, and the drain electrode 60 is connected to the pixel electrode 62 through the auxiliary capacitance electrode 64 via the contact hole 65. That is, the gate wiring 52a in the preceding stage is used as an auxiliary capacitance wiring for the pixels in the main stage.

In the present embodiment, the pixel electrode 6
At one end of the two sides on the TFT 55 side, there is provided a rectangular projecting portion 62a projecting from the side edge by a predetermined width. Similarly, the TFT 55 on the other side of the pixel electrode 62
At the opposite end, a rectangular overhang 62b overhangs from the side edge by the predetermined width is provided. Then, the overhang amount of the overhang portions 62a, 62b is set to a width overlapping with the source wirings 54a, 54b located on both sides. Further, the lengths of the overhang portions 62a and 62b are the same.

On the other hand, the counter substrate has the following configuration. That is, the color filters 67 are arranged on the insulating substrate 66 as the opposite substrate made of glass at positions corresponding to the respective pixel electrodes 62 in the order of arrangement of red, green, and blue. Further, a black matrix 68 which is a light shielding film for preventing light leakage from between the pixel electrode 62 and the adjacent pixel electrode 62 and between the color filters 67, 67 is disposed. Further, a counter electrode 69 made of a transparent conductive material is provided on this upper layer.

The active matrix substrate 5
1 and the opposing substrate 66 are arranged at a predetermined interval with the pixel electrode 62 side and the opposing electrode 69 side facing each other.
The present active matrix type liquid crystal display device is constituted by sandwiching a liquid crystal layer 70 between the components 1 and 66 and enclosing the liquid crystal layer with a sealing material.

As described above, in the present embodiment, overhangs 62a and 62b are provided at the ends of both sides of the pixel electrode 62 so as to overlap the adjacent source wirings 54a and 54b. The lengths of the overhang portions 62a and 62b are the same. Further, the length of both overhang portions 62a and 62b is determined by the distance between the overhang portion 62a on the one side of the pixel electrode 62 and the overhang portion 62b 'on the other side of the adjacent pixel electrode 62' in the source wiring 54a. The above-mentioned overhang portions 62a, 6 where the pixel electrodes 62 do not overlap
The interval is set so that the capacitance between the source wirings 54a and 54b generated in the region between 2b 'and negligible is negligible.

Therefore, in the above structure, the overhanging portions 62a, 62b of the pixel electrode 62 are connected to the source lines 54a,
By overlapping or completely overlapping 54b, even if some misalignment occurs between the blocks in the photolithography process, the capacitance Csd1 and the capacitance Csd2 hardly change, and the transmittance difference between the blocks is small. Become.

For this purpose, (Csd1−
The value of Csd2) is substantially constant even if the blocks in the photolithography process are different, and the block separation can be prevented. FIG. 3 shows the photoalignment deviation dx and the amount of change of (Csd1-Csd2) between the active matrix liquid crystal display device according to the present embodiment and the conventional active matrix liquid crystal display device shown in FIGS. As can be seen from FIG. 3, by adopting a structure in which the respective portions 62a and 62b on both sides of the pixel electrode 62 are completely overlapped on the source wirings 54a and 54b, (Csd1-Csd2)
Can be reduced. As a result, block separation due to the misalignment can be suppressed.

That is, according to the present embodiment, it is possible to suppress the separation of the blocks due to the variation in the coupling capacitance Csd between the source lines 54a and 54b and the pixel electrode 62.

<Second Embodiment> FIG. 4 is a plan view of an active matrix substrate in an active matrix type liquid crystal display device of the present embodiment. FIG. 5 is a cross-sectional view of the active matrix type liquid crystal display device shown in FIG.
It is arrow sectional drawing corresponding to B '.

4 and 5, an active matrix substrate 71, a gate wiring 72, a gate insulating film 73, T
FT 75, interlayer insulating film 76, auxiliary capacitance electrode 78, contact hole 79, counter substrate 80, color filter 81, black matrix 82, counter electrode 83, and liquid crystal layer 84
Are the active matrix substrate 51, the gate wiring 52, the gate insulating film 53, the TFT 55, the interlayer insulating film 61, the auxiliary capacitance electrode 64, the active matrix substrate 51 in the first embodiment shown in FIGS.
Contact hole 65, counter substrate 66, color filter 6
7, has the same configuration as the black matrix 68, the counter electrode 69, and the liquid crystal layer 70, and functions similarly.

The pixel electrode 77 in the present embodiment is formed in a straight line without any overhanging portions overlapping the source wiring 74 on both sides thereof, and is formed in a rectangular shape. On the other hand, the source wiring 74 connects the pixel electrode 77 to the TFT 7.
It is bent at a position bisecting the 5th side and the anti-TFT 75 side. Further, TF is larger than the bent portion of the source wiring 74.
Approximately 1/2 of the T75 side is the pixel electrode 7 located on one side.
7 ′ with an interlayer insulating film 76 interposed therebetween. On the other hand, approximately one half of the source line 74 on the opposite side to the TFT 75 from the bent portion overlaps with the pixel electrode 77 located on the other side via the interlayer insulating film 76.

Therefore, in the above structure, a part of both sides of the pixel electrode 77 overlaps or completely overlaps the source wirings 74 ′ and 74, which causes a slight misalignment between the blocks in the photolithography process. Also, the capacitance Csd1 and the capacitance Csd2 hardly change, and the transmittance difference between the blocks is reduced.

Further, according to the present embodiment, the pixel electrode 77 can be formed in a rectangular shape as in the conventional active matrix type liquid crystal display device shown in FIGS. Therefore, the formation of the color filter 81 and the black matrix 82 is facilitated.

<Third Embodiment> FIG. 6 is a plan view of an active matrix substrate in an active matrix type liquid crystal display device of the present embodiment. FIG. 7 is a cross-sectional view of the active matrix type liquid crystal display device shown in FIG.
It is arrow sectional drawing corresponding to C '.

6 and 7, an active matrix substrate 91, a gate wiring 92, a gate insulating film 93, source wirings 94 and 94 ', a TFT 95, an interlayer insulating film 96, an auxiliary capacitance electrode 98, a contact hole 99, and a counter substrate 100 are shown. ,
The color filter 101, the black matrix 102, the counter electrode 103, and the liquid crystal layer 104 correspond to the active matrix substrate 5 in the first embodiment shown in FIGS.
1, gate wiring 52, gate insulating film 53, source wiring 54
a, 54b, TFT 55, interlayer insulating film 61, auxiliary capacitance electrode 6
4, has the same configuration as the contact hole 65, the counter substrate 66, the color filter 67, the black matrix 68, the counter electrode 69, and the liquid crystal layer 70, and functions similarly.

In the pixel electrode 97 in the present embodiment, both side edges are bent at positions bisected in the extending direction of the source wirings 94, 94 'to form overhangs on both sides.
An overhanging portion of one side of the pixel electrode 97 closer to the TFT 95 than the bent portion overlaps the source wiring 94 ′ adjacent to the one side via the interlayer insulating film 96. . On the other hand, a substantially half-extended portion of the other side of the pixel electrode 97 opposite to the bent portion on the side opposite to the TFT 95 overlaps with the source line 94 adjacent to the other side via the interlayer insulating film 96. ing.

Therefore, in the above structure, the overhanging portion of the pixel electrode 97 overlaps or completely overlaps with the source wirings 94, 94 '. The capacitance Csd1 and the capacitance Csd2 hardly change, and the transmittance difference between the blocks is reduced.

Further, according to the present embodiment, a bent portion is formed at the center of both sides of the pixel electrode 97 to form a projecting portion, and the projecting portion has a length substantially equal to half the side edge of the pixel electrode 97. Covers the source wiring 94. Therefore, as compared with the case of the first embodiment, the pixel electrodes 62 are partially covered with the projecting portions 62a, 62b shorter than half the side edges of the pixel electrodes 62 so that the source lines 54a, 54b are partially covered. Variations in the capacitance Csd between the source line 97 and the source line 94 can be suppressed. Therefore, the block division can be further reduced.

Further, since the pixel electrode 97 is bent on the source lines 94 and 94 ', the aperture ratio can be increased as compared with the case where the pixel electrode 97 is not bent. In particular, 15
In a large active matrix type liquid crystal display device having a size of not less than inches, delay of a source signal, disconnection failure of a source wiring, and the like become problems. For this reason, it is necessary to reduce the length of the source wiring even slightly. The source wirings 94 and 94 'in the present embodiment are linearly arranged. Therefore, the length of the source wirings 94 and 94 'can be reduced as compared with the case where the source wiring 74 is bent near each pixel electrode 77 as in the second embodiment shown in FIG. And in the case of a disconnection failure of the source wiring.

FIGS. 8 and 9 are plan views of an active matrix substrate according to a modification of the present embodiment and FIGS.
1 is a cross-sectional view of an active matrix type liquid crystal display device corresponding to DD ′ of FIG.

In this modification, the tips of the projections 111 a and 111 b of the pixel electrode 111 extend beyond the source wiring 112 to the adjacent pixel side. By doing so, the pixel electrode 111 can be
Can be sufficiently overlapped, the alignment margin at the time of forming the pixel electrode is further increased, and the block division can be further suppressed.

The pixel electrode 111 is connected to the TFT 113
The storage capacitor electrode 116 is connected to the pixel electrode 111 via the contact hole 117.

<Fourth Embodiment> FIG. 10 is a plan view of an active matrix substrate in an active matrix type liquid crystal display device of the present embodiment. FIG. 11 is a cross-sectional view of the active matrix type liquid crystal display device taken along line EE ′ of FIG.

10 and 11, an active matrix substrate 121, a gate wiring 122, a gate insulating film 1 are shown.
23, source wiring 124, TFT 125, interlayer insulating film 12
6, the pixel electrode 127, the auxiliary capacitance electrode 128, the contact hole 129, the counter substrate 130, the counter electrode 133, and the liquid crystal layer 134 are the same as the insulating substrate 91, the gate wiring 92, and the gate in the third embodiment shown in FIGS. Insulating film 93,
Source wiring 94, 94 ', TFT 95, interlayer insulating film 96, pixel electrode 97, auxiliary capacitance electrode 98, contact hole 99,
It has the same configuration as the counter substrate 100, the counter electrode 103, and the liquid crystal layer 104, and functions similarly.

In this embodiment, as in the case of the modification of the third embodiment, the tip of the projection of the pixel electrode 127 extends beyond the source wiring 124 to the adjacent pixel side. And the pixel electrode 127 is T
Drain electrode 136 of FT125 and contact hole 1
37, and the auxiliary capacitance electrode 128 is connected to the pixel electrode 127 via the contact hole 129.

In the present embodiment, a light-shielding film 135 made of the same material as that of the gate wiring 122 is arranged in the same layer as the gate wiring 122 so as to shield light between the adjacent pixel electrodes 127 and 127. Therefore, the counter substrate 13
It is not necessary to dispose the black matrix 132 at a position between the adjacent pixel electrodes 127 and 127 on
It may be formed only on the FT 125.

Generally, the alignment accuracy between the active matrix substrate 121 and the counter substrate 130 is ± 5 μm.
m. On the other hand, the alignment accuracy between the layers of the active matrix substrate 121 is ± 1 μm or less. Therefore, the active matrix substrate 12
By arranging the light shielding film 135 on one side, the light shielding film 1
35 can be made narrower than the black matrix 132 and the black matrix 132 can be omitted. As a result, the area of the color filter 131 can be increased and the aperture ratio can be improved.

Further, since the area of the black matrix 132 disposed on the counter substrate 130 side is reduced, the bonding margin between the active matrix substrate 121 and the counter substrate 130 can be increased.

In this embodiment, the arrangement of the light-shielding film 135 and the deletion of the black matrix 132 due to the arrangement are applied to the third embodiment.
Even if it is applied to the first and second embodiments, it does not matter.

In each of the above embodiments, the TFTs 55, 75, 95, 113, and 125 are connected to the pixel electrodes 62, 77, 97, 111, 127 and
In the lower layer near the gap with 2,77,97,111,127, it is arranged via interlayer insulating films 61,76,96,126. Therefore, originally the black matrix 68, 82, 1
02, 132 are arranged in the vicinity of the area where they should be arranged. Therefore, the TFTs 55, 75, 95, 113, 12
It is not necessary to arrange a dedicated black matrix, and it is possible to prevent the areas of the black matrices 68, 82, 102, 132 from increasing more than necessary. Therefore, the aperture ratio can be increased.

Further, in each of the above embodiments, the formation areas of the black matrices 68, 82, 102 and 132 are set as follows. In other words, one side edge facing the pixel electrode on the side that covers the source wiring at a position facing between the two pixel electrodes adjacent to each other on the counter substrate is covered with the one side. Including the center line of the source wiring (in the case of FIGS. 4, 6, 8, and 10) and inside the pixel electrode from the center line (in the case of FIG. 1).
Set to be located at. On the other hand, the other side edge is set so as to be separated from the side edge of the signal wiring opposite to the pixel electrode by at least the alignment margin between the counter substrate and the active matrix substrate.

By doing so, the black matrices 68, 82, 102, and 13 arranged on the counter substrate are formed.
2 are set in consideration of the alignment margin between the counter substrate and the active matrix substrate. Therefore, even if there is a misalignment between the two substrates, light can be reliably shielded between the pixel electrodes adjacent to each other, and the block division can be further suppressed.

In each of the above embodiments, the bent portions of the pixel electrodes 97, 111, and 127 and the bent portion of the source wiring 74 are provided at the center positions of the pixel electrodes 77, 97, 111, and 127. However, in order to suppress the shadowing phenomenon and the block separation, it is not necessary to provide the bent portion exactly at the center of the pixel electrode. Therefore, the present invention does not limit the position of the bent portion provided in the pixel electrode or the source wiring to only the center position of each pixel electrode.

Further, according to the present invention, to the extent that the same effects as in the above-described embodiments can be obtained, there is a portion that is not slightly covered in the width direction of the source wiring (signal wiring) on both sides (overhangs) of the pixel electrode. No problem.

[0075]

As is clear from the above, the present invention provides
The two signal lines adjacent to the pixel electrode are covered in the width direction at a part of both sides of the pixel electrode along the signal line. Therefore, the difference between the first capacitance between the pixel electrode and the signal wiring adjacent to one side and the second capacitance between the pixel electrode and the signal wiring adjacent to the other side is defined as a layer. Even if there is a misalignment between them, it can be prevented from changing significantly. That is, according to the present invention, block separation that occurs when the photolithography process is performed in units of blocks can be suppressed.

In the active matrix type liquid crystal display device of the present invention, if the switching element is covered with the pixel electrode, the pixel electrode can be arranged on the switching element. Therefore, the pixel electrodes can be arranged in a substantially rectangular shape, and the area of the pixel electrodes can be increased to reduce power consumption.

Further, in the active matrix type liquid crystal display device of the present invention, the signal wirings located near the first and second pixel electrodes adjacent to each other are bent, and one of the first and second pixel electrodes is set with the bent portion as a boundary. If it is made to cover in the width direction with the above-mentioned bending as a boundary, and the other is covered in the width direction by the second pixel electrode, a part of both sides along the signal wiring in the pixel electrode is connected to the pixel electrode. A structure in which two adjacent signal lines are covered in the width direction can be obtained using a rectangular pixel electrode. Therefore, it is possible to easily form a color filter disposed on the opposing substrate facing the insulating substrate and a black matrix disposed at a position between the mutually adjacent image electrodes on the opposing substrate.

Further, in the active matrix type liquid crystal display device of the present invention, if the both sides of the pixel electrode are bent to form an overhang, and the adjacent signal wiring is covered in the width direction by the overhang, It is possible to obtain a structure in which a part of both sides of the pixel electrode along the signal wiring covers the two signal wirings adjacent to the pixel electrode in the width direction using the linear signal wiring. Therefore,
The length of the signal wiring can be shortened, and problems such as a delay of a source signal and a disconnection failure of the signal wiring which occur when a large active matrix type liquid crystal display device having a size of 15 inches or more can be reduced.

In the active matrix type liquid crystal display device according to the present invention, if the switching elements are arranged in the vicinity of two pixel electrodes adjacent to each other, the switching elements are adjacent to each other, which is an area to be shielded from light. In the vicinity of the pixel electrodes. Therefore, there is no need to arrange a black matrix dedicated to the switching element, and an increase in the area of the black matrix can be prevented, and a large aperture ratio can be obtained.

Further, in the active matrix type liquid crystal display device of the present invention, when a black matrix for shielding light between pixel electrodes adjacent to each other is disposed on a counter substrate facing the insulating substrate, the signal wiring is covered. The one side edge facing the pixel electrode on the side including the center line of the covered signal wiring is positioned inside the pixel electrode with respect to the center line of the covered signal wiring, while the other side edge is positioned at the signal side. If the wiring is located at a distance more than the alignment margin between the counter substrate and the insulating substrate from the side edge of the wiring opposite to the pixel electrode, the arrangement position of the black matrix can be adjusted to the alignment margin between the counter substrate and the insulating substrate. Can be set in consideration of Therefore, even if there is misalignment between the two substrates, light can be reliably shielded between the pixel electrodes adjacent to each other, and the block separation can be further suppressed.

In the active matrix type liquid crystal display device according to the present invention, if a light-shielding film is disposed at a position between pixel electrodes adjacent to each other on the insulating substrate, the alignment accuracy between the layers on the insulating substrate can be improved. Since the alignment accuracy between the insulating substrate and the opposing substrate is smaller, the width of the light-shielding film can be smaller than that of the black matrix arranged on the opposing substrate side. Therefore, the aperture ratio can be improved in combination with the fact that the black matrix can be eliminated.

Further, since the area of the black matrix arranged on the counter substrate side is reduced, the bonding margin between the insulating substrate and the counter substrate can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view of an active matrix substrate in an active matrix type liquid crystal display device of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ in FIG.

FIG. 3 is a diagram illustrating a photoalignment deviation and a change amount of a coupling capacitance.

FIG. 4 is a plan view of an active matrix substrate different from FIG.

FIG. 5 is a sectional view taken along the line BB ′ in FIG. 4;

FIG. 6 is a plan view of an active matrix substrate different from FIGS. 1 and 4;

FIG. 7 is a sectional view taken along the line CC ′ in FIG. 6;

FIG. 8 is a plan view of an active matrix substrate different from FIGS. 1, 4, and 6;

FIG. 9 is a sectional view taken along the line DD ′ in FIG. 8;

FIG. 10 is a plan view of an active matrix substrate different from FIGS. 1, 4, 6, and 8;

FIG. 11 is a sectional view taken along the line EE ′ in FIG. 10;

FIG. 12 is a plan view of a general active matrix liquid crystal display device.

13 is a cross-sectional view of one pixel portion of the active matrix liquid crystal display device shown in FIG.

14 is a plan view of one pixel portion of the active matrix liquid crystal display device shown in FIG.

FIG. 15 is a cross-sectional view of a conventional active matrix liquid crystal display device in which a pixel electrode is overlaid on a signal line.

16 is a plan view of the active matrix substrate in FIG.

17 is an equivalent circuit diagram of the active matrix substrate shown in FIG.

FIG. 18 is an explanatory diagram of misalignment of a pixel electrode.

FIG. 19: Pixel electrode misalignment and pixel electrode /
FIG. 6 is a diagram illustrating a relationship between capacitance and adjacent signal wiring.

FIG. 20 is a diagram illustrating a relationship between an alignment shift and a difference in transmittance with respect to a block having no alignment shift.

[Explanation of symbols]

51, 71, 91, 121 ... active matrix substrate, 52, 52a, 72, 92, 122 ... gate wiring (scanning wiring), 54 a, 54 b, 74, 94, 112, 124 ... source wiring (signal wiring), 55, 75, 95, 113, 125 ... TFT, 60, 114, 136 ... drain electrode, 61, 76, 96, 126 ... interlayer insulating film, 62, 77, 97, 111, 127 ... pixel electrode, 64, 78, 98, 116, 128: auxiliary capacitance electrode, 65, 79, 99, 115, 117, 129, 137: contact hole, 66, 80, 100, 130: counter substrate, 67, 81, 101, 131: color filter, 68, 82 , 102, 132: black matrix; 69, 83, 103, 133: counter electrode; 70, 84, 104, 134: liquid crystal layer; 135: light shielding film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/336 F term (Reference) 2H091 FA34Y FA35Y FD04 GA03 GA11 GA13 LA16 2H092 GA13 JA34 JA35 JA46 JB27 JB32 JB33 JB36 JB52 JB64 JB67 JB69 KA05 KB04 KB25 NA07 NA23 NA24 PA06 PA09 5C094 AA04 AA08 AA10 AA13 AA14 AA22 AA32. EE04 FF03 GG02 GG15 GG25 GG44 HK03 HK04 HK09 HK21 NN04 NN73 QQ08

Claims (7)

[Claims] A plurality of scanning lines formed on an insulating substrate; a plurality of signal lines intersecting the scanning lines; and a plurality of signal lines arranged in a matrix near each intersection of the scanning lines and the signal lines. In the active matrix type liquid crystal display device having the switching elements and the pixel electrodes connected to the output terminals of the switching elements and arranged in a matrix, a part of both sides of the pixel electrode is adjacent to the pixel electrode. An active matrix liquid crystal display device, wherein the two signal lines are covered in a width direction. 2. The active matrix liquid crystal display device according to claim 1, wherein said pixel electrode covers said switching element. 3. The active matrix type liquid crystal display device according to claim 1, wherein the signal wiring is bent near the first and second pixel electrodes adjacent to each other, with the bent portion as a boundary. One side is the first
An active matrix liquid crystal display device, wherein the liquid crystal display device is covered in the width direction by a pixel electrode, and the other is covered in the width direction by the second pixel electrode at the above-mentioned bending. 4. The active matrix liquid crystal display device according to claim 1, wherein both side edges of the pixel electrode along the signal wiring are bent to form overhanging portions on both side portions. The active matrix type liquid crystal display device, wherein the adjacent signal wiring is covered in the width direction by the overhang portion. 5. The active matrix type liquid crystal display device according to claim 1, wherein the switching element is arranged near two pixel electrodes adjacent to each other. Active matrix type liquid crystal display device. 6. The active matrix liquid crystal display device according to claim 1, wherein the opposing substrate is disposed to oppose the insulating substrate, and is adjacent to the opposing substrate. One side edge, which is arranged at a position facing between the two pixel electrodes and faces the pixel electrode that covers the signal wiring, includes the center line of the covered signal wiring. The other side edge is located on the inner side of the pixel electrode from the center line, and the other side edge is located at least the alignment margin between the counter substrate and the insulating substrate from the side edge of the signal wiring opposite to the pixel electrode. An active matrix type liquid crystal display device comprising a black matrix. 7. The active matrix liquid crystal display device according to claim 1, further comprising: a light-shielding film disposed at a position between pixel electrodes adjacent to each other on the insulating substrate. An active matrix type liquid crystal display device characterized by the above-mentioned.