JP2640585B2 - 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 structure of a so-called active matrix type liquid crystal display device in which a switching element section and a storage capacitor section are added for each of a plurality of picture element electrodes constituting a display screen. is there.

[0002]

2. Description of the Related Art FIG. 4 is an enlarged plan view showing a part of a conventional active matrix type liquid crystal display device 1, and FIG.
FIG. 5 is a sectional view taken along line AA of FIG. 4. As shown in the drawing, the conventional active matrix type liquid crystal display device 1 has a plurality of transparent picture element electrodes 2 arranged in a matrix on a display screen on a glass substrate 6. A non-linear switching element unit (thin film transistor) 3 for turning on / off the voltage to the pixel electrode unit 2 is provided beside each of the pixel electrode units 2.
A transparent storage capacitor portion (thin film capacitor) Cs for holding the charge of the pixel electrode portion 2 and smoothly maintaining the ON-state potential thereof is formed in a pattern, and a switching element is provided between the pixel electrode portions 2. Gate bus lines 4 and source bus lines 5 for supplying drive signals to the section 3 are formed so as to intersect alternately.

[0003] The switching element section 3 is made of a glass substrate 6.
A thin film transistor (TFT) element 3a is formed on a gate electrode 7 extending from the gate bus line 4 via gate insulating films 8 and 9 (see FIG. 5).
On the element 3a, a source electrode 11 extending from the source bus line 5 and a drain electrode 12 connected to the pixel electrode section 2 are formed.

[0005] Further, as shown in FIG. 5, a conventional storage capacitor portion Cs includes a bus-line-shaped transparent lower conductive film 15 extending in parallel with the gate bus line 4 on a glass substrate 6, and the entire upper portion of the lower conductive film 15. Transparent gate insulating film 16, which covers
17 and the insulating film 16 using the same material as the pixel electrode portion 2.
17 and a transparent upper conductive film 20 deposited on the upper surface of the substrate 17.

In general, the upper conductive film 20 is separated from the picture element electrode part 2 when the storage capacitance part Cs whose insulation distance is delicately adjusted has a defect.
This is for facilitating the partial modification of only s.

[0006]

Generally, in order to form the storage capacitor portion Cs for increasing the charge retention, an extremely fine and complicated manufacturing process must be performed. In some cases, a shape error occurs at the end (pattern edge). Then, the lower conductive film 15
A part of the pattern edge approaches the upper conductive film 20, and a thin film part is generated in a part of the insulating films 16 and 17, so that a pixel defect due to a leak in the insulating films 16 and 17 occurs. There was.

That is, the conventional storage capacitor section C shown in FIG.
The same-direction pattern edges of both the upper conductive film 20 forming s and the lower conductive film 15 including the oxide film 16 are overlapped at the same position in the longitudinal direction of the film as shown by II in FIG. And the lower conductive film 15 forming the storage capacitor portion Cs
The pattern edge shape is a process-like problem, for example,
When the finished pattern shape is poor due to variations in the adhesion of the resist, exposure, etching, or the like, a leak occurs between the upper conductive film 20 and the lower conductive film 15 that form the storage capacitor portion Cs, and the display panel has a leak. It becomes a picture element defect.

Recently, techniques for repairing defective portions have been developed more and more, for example, by chemical vapor deposition (CV) using a laser.
D) and the like make it possible to cut lines of several microns or to connect broken lines. Therefore,
It is also possible to separate and correct only the storage capacitor portion Cs where the leak has occurred.

However, repairing an actual problem or a defective portion requires an enormous amount of time depending on the degree of difficulty of the correction accuracy or the correction range, and it is difficult to perform practical defect relief.

In view of the above problems, it is an object of the present invention to provide a liquid crystal display device capable of minimizing the generation of picture element defects that determine the most important display quality at the design stage.

[0011]

According to the first aspect of the present invention, as shown in FIGS. 1 to 3, a switching element section 3 is provided for each of a plurality of picture element electrodes 2 constituting a display screen on a transparent substrate 6. And a storage capacitor section Cs. The storage capacitor section Cs is separately disposed on the side of the pixel electrode section 2 and is connected to the pixel electrode section 2 via the connector 20a. 20, a lower conductive film 15 disposed below the upper conductive film 20 in a non-contact manner and in parallel with the upper conductive film 20, and an insulating film 1 interposed between the lower conductive film 15 and the upper conductive film 20.
6, 17 wherein the upper conductive film 20 and the lower conductive film 15 are patterned to form a pattern edge of the upper conductive film 20 so as to prevent leakage with the lower conductive film 15. The lower conductive film 15 is provided inside the pattern edge portion.

According to a second aspect of the present invention, there is provided a liquid crystal display device according to the first aspect, wherein the storage capacitor section C is provided.
s is formed so as to be divided into at least two or more portions with respect to the single pixel electrode portion 2, and the pattern edge portion of the upper conductive film 20 of each storage capacitor portion Cs prevents leakage with the lower conductive film 15. The lower conductive film 15 is arranged inside the pattern edge portion.

[0013]

According to the first and second aspects of the present invention, when the switching element section is driven to apply a voltage to the picture element electrode section, the voltage is applied to the storage capacitor section even if an excessive voltage is applied. To adjust the potential to improve the subsequent charge retention.

At this time, if there is a shape error in the pattern edge portion of the lower conductive film 15 as the ground electrode in the storage capacitor portion Cs, the thicknesses of the insulating films 16 and 17 become non-uniform, and the two conductive films 15 and 20 become non-uniform. Although there is a possibility that a leak may occur between them, since the pattern edge of the upper conductive film 20 is arranged inside the pattern edge of the lower conductive film 15,
The upper conductive film 20 can be formed only on flat portions where the thicknesses of the insulating films 16 and 17 are uniform, and leakage between the conductive films 15 and 20 can be prevented.

According to the second aspect of the present invention, a failure such as a shape error of a pattern edge portion of the upper conductive film 20 occurs in any one of the storage capacitor portions Cs and overlaps with the pattern edge portion of the lower conductive film 15. However, the storage capacity section Cs
Is divided into two or more parts, so that only the storage capacitor portion Cs in which a failure has occurred can be partially corrected, and fine adjustment can be performed.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an entire liquid crystal display device according to an embodiment of the present invention, FIG.
FIG. 3 is a sectional view taken along line AA of FIG. Note that members having the same functions as those of the related art are denoted by the same reference numerals.

In general, as shown in FIG. 1, the liquid crystal display device has transparent electrode plates Xa and Xb disposed on both front and rear surfaces of a liquid crystal layer G, and further has polarizing plates Ha and Hb laminated thereon. Then, the liquid crystal display device of this embodiment has the transparent electrode plates Xa, X
For b, the switching element section 3 and the transparent storage capacitor section (thin film capacitor) Cs are patterned by physical vapor deposition (PVD) such as sputtering or chemical vapor deposition (CVD) for each of the plurality of transparent picture element electrodes 2 constituting the display screen. The active matrix type is formed.

The picture element electrode section 2 is an existing one for applying a voltage to the liquid crystal molecules of the liquid crystal layer G to rotate the light distribution axis thereof. As shown in FIGS. It is formed on the glass substrate 6 with a nitride insulating film 17 interposed therebetween, for example.

As shown in FIG. 2, the switching element section 3 is an existing thin film transistor (TFT) element 3a for applying a voltage to the picture element electrode section 2, and is a gate bus line for supplying a drive signal made of tantalum. 4 and is connected to the source bus line 5 so that a current on the source bus line 5 flows to the pixel electrode unit 2 via the drain electrode 12 based on an on / off signal from the gate bus line 4. .

As shown in FIG. 2, the storage capacitor section Cs is formed so as to be at least divided into two or more with respect to a single picture element electrode section 2 so that partial correction can be made in small units when a defect occurs. I have. As shown in FIG. 3, the storage capacitor portion Cs is arranged separately on the side of the pixel electrode portion 2 and is connected to the connector 2.
Upper conductive film 20 connected to pixel electrode unit 2
And a non-contact upper conductive film 20 under the upper conductive film 20.
Lower conductive film 15 arranged in parallel to
Insulating films 16 and 17 interposed between the upper conductive film 20 and
It is composed of

The upper conductive film 20 is made of a transparent indium tin oxide (IT) made of the same material as that of the pixel electrode portion 2.
O) is used, and is patterned on the upper surface of the nitride insulating film 17.

The lower conductive film 15 is a conventional tantalum bus line formed on the glass substrate 6 in parallel with the gate bus line 4 and is grounded via an external wiring.

The insulating films 16 and 17 are formed of the lower conductive film 15.
Is a transparent two-layer film in which an anodic oxide film 16 covering the entire upper surface of the substrate and a nitride insulating film 17 extending from the lower surface of the picture element electrode portion 2 are laminated.

In the liquid crystal display device of this embodiment, as shown in FIGS. 2 and 3, the pattern edge of the upper conductive film 20 overlaps with the pattern edge of the lower conductive film 15 where a shape error may occur. In order to avoid this, they are arranged shifted inward from this. Here, the reason why the pattern edge portion of the upper conductive film 20 is formed not inside but outside the pattern edge portion of the lower conductive film 15 is that the upper conductive film 20 is formed only on the plane portions of the insulating films 16 and 17. This is to prevent the occurrence of a leak due to a shape error of the pattern edge portion of the lower conductive film 15. The distances L1 and L2 from the starting point of the rise of the insulating films 16 and 17 in the pattern edge portion of the upper conductive film 20 are about 1 to 5 μm.

In the above configuration, as shown in FIG. 2, a voltage is applied to one of the plurality of source bus lines 5,
When an ON signal is given to one of the plurality of gate bus lines 4, the switching element unit 3 adjacent to the intersection of the two bus lines 4 and 5 is driven to drive the pixel electrode unit 2
To rotate the light distribution axis of the liquid crystal molecules in the liquid crystal layer G as shown in FIG.

Here, even if a charge is applied to the pixel electrode portion 2 more than necessary, the storage capacitor portion C connected by the connector 20a
s, the potential can be adjusted, and the storage capacitor Cs can improve the subsequent charge retention rate.

At this time, if there is a shape error in the pattern edge portion of the lower conductive film 15 as the ground electrode in the storage capacitor portion Cs, the thicknesses of the insulating films 16 and 17 become non-uniform, and the two conductive films 15 and 20 become uneven. Leakage may occur between the two. However, in the present embodiment, as shown in FIGS. 2 and 3, the pattern edge portion of the upper conductive film 20 is disposed inside the pattern edge portion of the lower conductive film 15, so that the insulating films 16 and 1 are formed.
The upper conductive film 20 can be prevented from overlapping the portion where the thickness of the layer 7 is not uniform. Accordingly, the rate of occurrence of leakage between the two conductive films 15 and 20 is extremely reduced, and both the display quality and the yield of the liquid crystal display device are improved.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. For example, in the present embodiment, the structure relating to the transistor element 3a, which is a three-terminal element, has been described as the switching element section 3. However, for example, a two-terminal element diode or the like can be applied.

[0029]

As is apparent from the above description, according to the first and second aspects of the present invention, the pattern edge of the upper conductive film is disposed inside the pattern edge of the lower conductive film. Even if there is a shape error in the pattern edge portion, the upper conductive film can be formed only on a flat portion where the thickness of the insulating film is uniform, and the occurrence of a leak between the two conductive films can be prevented.

According to the second aspect of the present invention, since the storage capacitor portion is formed by dividing the storage capacitor portion into two or more divisions, any one of the storage capacitor portions has a shape error of the pattern edge portion of the upper conductive film. Even if a failure occurs and overlaps with the pattern edge portion of the lower conductive film 15, only the storage capacitor portion in which the failure has occurred can be partially corrected and fine adjustment can be performed. .

[Brief description of the drawings]

FIG. 1 is a side view showing an entire liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of the same.

FIG. 3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a partially enlarged plan view of a conventional liquid crystal display device.

FIG. 5 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

2 picture element electrode part 3 switching element part (thin film transistor (TF
T) element portion) 6 transparent substrate 15 lower conductive film 16, 17 insulating film 20 upper conductive film Cs storage capacitor portion

Claims (2)

(57) [Claims] 1. A switching element section and a storage capacitor section are provided for each of a plurality of picture element electrode sections constituting a display screen on a transparent substrate, and the storage capacitor section is separated from a side of the picture element electrode section. An upper conductive film, which is disposed and connected to the pixel electrode portion via a connector, a lower conductive film disposed below the upper conductive film in a non-contact manner and in parallel with the upper conductive film, and the lower conductive film And an insulating film interposed between the upper conductive film and
In a liquid crystal display device in which the upper conductive film and the lower conductive film are patterned, the pattern edge of the upper conductive film is disposed inside the pattern edge of the lower conductive film so as to prevent leakage with the lower conductive film. A liquid crystal display device characterized by the above-mentioned. 2. The liquid crystal display device according to claim 1, wherein
The storage capacitor portion is formed so as to be separated into at least two or more portions with respect to a single pixel electrode portion, and the pattern edge portion of the upper conductive film of each storage capacitor portion prevents leakage with the lower conductive film. A liquid crystal display device disposed inside the pattern edge portion of the lower conductive film.