JP3867191B2 - Active matrix liquid crystal display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active matrix liquid crystal display panel.
[0002]
[Prior art]
FIG. 3 is a partially transparent plan view of an example of a conventional active matrix type liquid crystal display panel, and FIG. 4 is a sectional view taken along the line XX. This liquid crystal display panel includes a glass substrate 1. A scanning signal line 2 and a data signal line 3 are provided in a matrix on the upper surface side of the glass substrate 1, and a thin film transistor 4 and a pixel electrode 5 are provided in the vicinity of each intersection, and further in parallel with the scanning signal line 2. A capacity line 6 is provided.
[0003]
That is, the scanning signal line 2 including the gate electrode 7 is provided at a predetermined location on the upper surface of the glass substrate 1, the auxiliary capacitance line 6 is provided at the other predetermined location, and the entire upper surface is made of silicon nitride or the like. A gate insulating film 8 is provided. A semiconductor thin film 9 made of intrinsic amorphous silicon is provided on the upper surface of the gate insulating film 8 on the gate electrode 7. A channel protective film 10 made of silicon nitride or the like is provided at the center of the upper surface of the semiconductor thin film 9. Ohmic contact layers 11 and 12 made of n-type amorphous silicon are provided on both sides of the upper surfaces of the semiconductor thin film 9 and the channel protective film 10.
[0004]
A data signal line 3 including a drain electrode 13 is provided at a predetermined location on the upper surface of one ohmic contact layer 11 and the upper surface of the gate insulating film 8. A source electrode 14 is provided at another predetermined position on the upper surface of the other ohmic contact layer 12 and the upper surface of the gate insulating film 8. An overcoat film 15 made of silicon nitride or the like is provided on the entire upper surface. A pixel electrode 5 made of ITO or the like is provided at a predetermined location on the upper surface of the overcoat film 15. The pixel electrode 5 is connected to the source electrode 14 through a contact hole 16 provided in the overcoat film 15. In the liquid crystal display panel having a cross-sectional structure as described above, since the ITO constituting the pixel electrode 5 is located on the top side of the thin film transistor 4, it may be referred to as a TOP-ITO structure.
[0005]
By the way, the source electrode 14 is substantially L-shaped in a plane, and a portion (hereinafter referred to as an auxiliary capacitance forming region) 14 a extending in the left-right direction in FIG. 3 is overlapped with the auxiliary capacitance line 6. An auxiliary capacity portion is formed by the overlapped portion. That is, in a normal liquid crystal display panel in which the pixel electrode is formed on the gate insulating film, the auxiliary capacitance portion is formed by the overlapping portion of the auxiliary capacitance line and the pixel electrode, whereas in the TOP-ITO structure, the source electrode 14 Therefore, the source electrode 14 extends in a strip shape along the auxiliary capacitance line 6.
[0006]
In this case, the width D1 of the auxiliary capacitance forming region 14a is smaller than the width D2 of the auxiliary capacitance line 6, and the auxiliary capacitance forming region 14a is disposed within the width of the auxiliary capacitance line 6. This is because the step of forming the source electrode 14 and the step of forming the auxiliary capacitance line 6 are separate, so that even if a vertical displacement occurs in FIG. 3, the auxiliary capacitance line 6 in the auxiliary capacitance formation region 14a is formed. This is because the auxiliary capacitance is made uniform so that the overlapping area does not change. The upper side of the pixel electrode 5 in FIG. 3 is disposed between the upper end of the auxiliary capacitance line 6 in FIG. 3 and the lower end of the scanning signal line 2 in FIG. In this case, the auxiliary capacitance line 6 also has a function as a light shielding film, and the lower side of the lower end in FIG. 3 is a substantial pixel portion.
[0007]
[Problems to be solved by the invention]
However, in such a conventional liquid crystal display panel, as shown in FIG. 3, the auxiliary capacitance line 6 is made thicker than the width of the auxiliary capacitance forming region 14 a, and the upper end of the auxiliary capacitance line 6 is the lower end of the scanning signal line 2. Since they are close to each other, there has been a problem that the gate-pixel coupling capacitance Cgs increases and the display quality deteriorates.
An object of the present invention is to reduce a coupling capacitance between a pixel electrode and a scanning signal line.
[0008]
[Means for Solving the Problems]
The active matrix type liquid crystal panel according to the present invention includes a substrate, a scanning signal line formed on the substrate, a gate electrode connected to the scanning signal line, the scanning signal line and the gate electrode, and the scanning signal. An auxiliary capacitance line formed along the line; a gate insulating film formed on the substrate including the scan signal line, the gate electrode, and the auxiliary capacitance line; and above the gate electrode. A semiconductor layer formed on the gate insulating film, a source electrode and a drain electrode connected to the semiconductor layer, and an overcoat film formed on the gate insulating film including the source electrode and the drain electrode. A pixel electrode connected to the source electrode through the contact hole, and the source electrode The auxiliary capacitor part is formed between the auxiliary capacitor line by extending to the outer side of the body layer and overlapping the auxiliary capacitor line with the gate insulating film sandwiched between the extended outer layer and the source. One side closest to the scanning signal line among the sides extending along the scanning signal line provided on the outside where the electrode extends is a side extending along the scanning signal line provided on the pixel electrode. Of the storage capacitor line and the side of the auxiliary capacitance line extending along the scanning signal line, the side closest to the scanning signal line, and closer to the scanning signal line. The scanning is performed out of the sides extending along the scanning signal line that is disposed at a position and the source electrode is provided on the extended outside. One side farthest from the signal line is arranged at a position farther from the scanning signal line than one side farthest from the scanning signal line among the sides extending along the scanning signal line of the auxiliary capacitance line. Yes . According to the present invention, one side closest to the scanning signal line among the sides extending along the scanning signal line provided outside the source electrode is extended along the scanning signal line provided in the pixel electrode. One of the adjacent sides that is closest to the scanning signal line and one of the sides that extend along the scanning signal line of the auxiliary capacitance line that is closest to the scanning signal line are arranged at a position closer to the scanning signal line. Therefore, the auxiliary capacitor line is disposed between the pixel electrode and the scanning signal line due to the shielding effect of the auxiliary capacitor forming region disposed between the scanning signal line and one side closest to the scanning signal line of the pixel electrode. It is possible to reduce the coupling capacity.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a transmission plan view of the main part of an active matrix liquid crystal display panel according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line XX. In these drawings, parts having the same names as those in FIGS. 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0010]
In the liquid crystal display panel of this embodiment, the width D4 of the auxiliary capacitance line 6 is formed smaller than the width D3 of the auxiliary capacitance formation region 14a. In this case, the width D4 of the auxiliary capacitance line 6 is set to a dimension that does not lie outside the width D3 of the auxiliary capacitance formation region 14a even when the auxiliary capacitance line 6 and the source electrode 14 are formed, even for the maximum misalignment of the mask. As a result, no change occurs in the auxiliary capacitance of the pixel due to misalignment.
[0011]
In this structure, since the auxiliary capacitance is formed by the overlapping portion of the source electrode 14 and the auxiliary capacitance line 6, the pixel electrode 14 can be connected to the source electrode 14 without considering the overlapping area with the auxiliary capacitance line 6. Since it is only necessary to be connected, one side of the upper end side is formed so as to be positioned farther from the scanning signal line 2 than the upper end of the auxiliary capacitance forming region 14a of the source electrode 14.
[0012]
As described above, in the present invention, the upper end of the auxiliary capacitance line 6 is greatly separated from the lower end of the scanning signal line 2, and one side of the upper end side of the pixel electrode 5 is the auxiliary capacitance forming region 14 a of the source electrode 14. Is formed at a position farther from the scanning signal line 2 than the upper end thereof, and the shielding effect by the auxiliary capacitance forming region 14a acts, so that the gate-pixel coupling capacitance Cgs can be reduced.
[0013]
If the width D4 of the auxiliary capacitance line 6 shown in FIG. 1 is the same as the width D1 of the auxiliary capacitance forming region 14a shown in FIG. 3, the capacitance of the auxiliary capacitance portion can be made substantially the same as that shown in FIG. . In this case, since the auxiliary capacitance line 6 is disposed within the width of the auxiliary capacitance forming region 14a, if the auxiliary capacitance forming region 14a has a function as a light shielding film, the lower side of the lower side in FIG. A substantial pixel portion is obtained, and substantially the same aperture ratio as in the conventional case shown in FIG. 3 can be obtained.
[0014]
【The invention's effect】
As described above, according to the present invention, the side closest to the scanning signal line among the sides extending along the scanning signal line provided outside the source electrode is the scanning signal provided by the pixel electrode. One of the sides extending along the line that is closest to the scanning signal line and one of the sides extending along the scanning signal line of the auxiliary capacitance line that is closest to the scanning signal line are the scanning signal lines. since disposed proximate to the position, by the shield effect of the auxiliary capacitor formation region disposed between the nearest side to the scanning signal lines of the pixel electrode of the storage capacitor lines and the scanning signal lines, a pixel electrode A coupling capacity between the scanning signal lines can be reduced.
[Brief description of the drawings]
FIG. 1 is a transmission plan view of a main part of a liquid crystal display panel according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line XX in FIG.
FIG. 3 is a partially transparent plan view of an example of a conventional liquid crystal display panel.
4 is a cross-sectional view taken along line XX in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Scan signal line 3 Data signal line 4 Thin-film transistor 5 Pixel electrode 6 Auxiliary capacity line 14 Source electrode 14a Auxiliary capacity formation area

Claims (3)

A substrate, a scanning signal line formed on the substrate, a gate electrode connected to the scanning signal line, the scanning signal line, and an auxiliary capacitor formed so as to be separated from the gate electrode and along the scanning signal line A gate insulating film formed on the substrate including a line, the scanning signal line, the gate electrode, and the auxiliary capacitance line; and a semiconductor formed on the gate insulating film above the gate electrode A source electrode connected to the semiconductor layer and a drain electrode; and the source electrode via a contact hole provided in an overcoat film formed on the gate insulating film including the source electrode and the drain electrode. And a pixel electrode connected to
The source electrode extends to the outside of the semiconductor layer, and overlaps the auxiliary capacitance line with the gate insulating film sandwiched between the extended outer side, thereby forming an auxiliary capacitance portion between the auxiliary capacitance line. Forming,
Of the sides extending along the scanning signal line provided on the outside where the source electrode extends, one side closest to the scanning signal line extends along the scanning signal line provided on the pixel electrode. One of the sides that are closest to the scanning signal line and one of the sides that extend along the scanning signal line of the auxiliary capacitance line is closer to the scanning signal line than the one that is closest to the scanning signal line. Placed in close proximity,
Of the sides extending along the scanning signal line provided on the outside where the source electrode extends, one side farthest from the scanning signal line extends along the scanning signal line of the auxiliary capacitance line. An active matrix type liquid crystal panel, wherein the active matrix type liquid crystal panel is arranged at a position farther from the scanning signal line than one side farthest from the scanning signal line . 2. The active matrix liquid crystal display panel according to claim 1 , wherein the auxiliary capacitance line is formed so as to be inside the source electrode with respect to a maximum misalignment. 2. An active matrix liquid crystal display panel according to claim 1 , wherein the source electrode has a function as a light shielding film.

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