JP2687967B2 - Liquid crystal display - Google Patents

Description

The present invention relates to the structure of a liquid crystal display device.

2. Description of the Related Art In recent years, due to advances in fine processing technology and liquid crystal materials, television image display devices using liquid crystal panels have been provided on a commercial basis. Further, as a method, a so-called active method in which a switching element is built in for each picture element is becoming mainstream because of advantages such as high contrast and high resolution.

FIG. 3 shows an equivalent circuit of an active liquid crystal panel. For example, a switching element 4 of a field effect transistor and a liquid crystal cell 5 are arranged at each intersection of the scanning line group 2 and the signal line group 3. ing. Reference numeral 6 is a counter electrode formed of a transparent conductive layer common to all liquid crystal cells 5.

FIG. 4 is a plan view of a unit pixel of a general active system, and FIG. 5 is a sectional view taken along the line AA ′ in FIG. On the insulating substrate 1, for example, the glass substrate 1, the conductive layer 8 which also serves as the scanning line and the gate of the field effect transistor is formed, and the amorphous silicon layer 12 and the signal line 9 and the drain wiring are provided through the insulating layer 13. 10 is formed to form a field effect transistor. Here, 7 is a pixel electrode, and 11 is a contact part.

However, the above-mentioned structure has a problem that the yield is low because the structure is complicated. The greatest cause of this low yield is insulation failure of the insulating layer 13, such as the scan line 8
There is a short circuit between the signal line 9 and the signal line 9. This defect becomes a cross line defect on the image, which significantly deteriorates the display quality, which is a serious problem in practical use.

One of the causes of this short circuit failure is dielectric breakdown due to static electricity. This is because static electricity invades the scanning line group 2 or the signal line group 3 from the outside of the insulating substrate 1 to cause a potential difference between the scanning line 8 and the signal line 9, which causes the electrical breakdown voltage of the insulating layer 13. If it exceeds, dielectric breakdown occurs, resulting in a short circuit defect between the scanning line 8 and the signal line 9.

In order to prevent short-circuit defects due to this dielectric breakdown, thorough static elimination in the manufacturing process and careful handling are required. However, even if the above measures are taken, the occurrence rate of the short circuit defect can be reduced, but there is a problem that it cannot be a fundamental measure. Therefore, it is necessary to take a fundamental measure to prevent the potential difference between the scanning line and the signal line from occurring by short-circuiting the scanning line group 2 and the signal group 3 with the conductive thin film pattern.

However, since the conductive thin film short pattern has to be removed by etching or cutting in a process before displaying an image in order to obtain a normal image when displaying an image on a liquid crystal display device, a reduction in yield due to an increase in man-hours. However, there is a problem that reliability is deteriorated by etching and cutting.

In view of the above-mentioned problems, the present invention uses an insulating layer at the time of static electricity input without increasing the number of steps and reducing the reliability.
Provided is a liquid crystal display device having a structure for preventing a short circuit defect due to dielectric breakdown of an insulating layer between conductive thin film wirings of a layer.

Means for Solving the Problems According to the present invention, liquid crystal is sealed between a pair of substrates in order to prevent short-circuit defects due to dielectric breakdown of an insulating layer interposed between two layers of conductive thin film wiring during static electricity input. Pixel electrodes arranged in a matrix on the one substrate, a thin film transistor connected in proximity to the pixel electrode, a signal line connected to the source electrode of the thin film transistor, and a gate electrode of the thin film transistor. A liquid crystal display device having scan wirings connected to each other, wherein a first conductive thin film is formed on a portion of the inner surface of the substrate which is not electrically connected to either the signal wirings or the scan wirings. A liquid crystal display device is characterized in that a second conductive thin film is formed thereon so as to overlap the pattern of the first conductive thin film via an insulating layer.

The present invention has the above-described structure, and when static electricity is applied from the outside of the substrate, the static electricity is dispersed by the strip-shaped conductive thin film pattern formed so as to surround the outer periphery of the substrate, and the static electricity is locally concentrated between the wirings. It is possible to prevent short circuit defects due to dielectric breakdown. In addition, when two or more layers of the strip-shaped conductive thin film pattern form a capacitance, the capacitance formed by the two or more layers of the strip-shaped conductive thin film pattern through the insulating layer when static electricity is externally applied to the substrate. It is possible to prevent static electricity from being canceled by static electricity due to the charge accumulated in the wiring, or to cause dielectric breakdown between the strip-shaped conductive thin film patterns in advance to prevent dielectric breakdown due to invasion of static electricity between wirings.

Embodiments FIGS. 1 (a) and 1 (b) are perspective views of an active type liquid crystal panel according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line BB ′ of FIG.

First, as shown in FIG. 1 (a), the first conductive layer is formed on the inner surface of the substrate 1 on which the active liquid crystal panel is formed and which is not electrically connected to either the signal wiring or the scanning wiring. The thin film 14 is formed into a strip shape. After depositing an insulating layer 16 thereon as shown in FIG. 2, a second conductive thin film pattern 15 is formed so as to overlap the first conductive thin film pattern 14. At this time, the first conductive thin film pattern 14 and the second conductive thin film pattern 15 may have a perfect strip shape as shown in FIG. 1 (a), or as shown in FIG. 1 (b). The conductive thin film pattern of the book may have a strip shape in which one or both of them are cut in the middle. Note that the conductive thin film pattern 14 and the conductive thin film pattern 15 do not have to overlap the entire pattern, and may be a part of the pattern.

In addition, for example, when forming the scanning line 8, a conductive thin film pattern is formed.
If 14 is formed and the conductive thin film pattern 15 is formed when the signal line 9 is formed, the number of steps is not increased and the yield is not reduced.

As described above, according to this embodiment, when static electricity is applied from the outside of the insulating substrate 1, the static electricity is dispersed due to the strip-shaped shapes of the first and second conductive thin film patterns 14 and 15, and It is possible to prevent a short circuit defect due to the dielectric breakdown of the cross portion of the scanning line 2 and the signal line 3 due to the application of the pole portion. In addition, static electricity applied from the outside of the insulating substrate 1 is canceled by the electric charge accumulated in the capacitance formed by the first and second conductive thin film patterns 14 and 15, and the static electricity enters the wirings 2 and 3. Can be prevented.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to prevent static electricity from invading the wiring from the outside to the active type liquid crystal panel substrate, and the occurrence of short circuit defects is dramatically reduced. There is a great effect.

[Brief description of the drawings]

1 (a) and 1 (b) are perspective views of an active type liquid crystal panel according to an embodiment of the present invention, and FIG. 2 is FIG. 1 (a),
FIG. 4B is a cross-sectional view taken along line BB ′ of FIG. 3B, FIG. 3 is a perspective view of a conventional active type liquid crystal panel, FIG. 4 is a plan view of a unit pixel of the liquid crystal panel, and FIG. It is sectional drawing of the AA 'line of a figure. 1 ... Insulating substrate, 14, 15 ... First and second conductive thin film, 1
6 ... Insulating layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Otomo 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 63-274930 (JP, A) JP 62- 264027 (JP, A) JP-A-63-25683 (JP, A)

Claims (1)

(57) [Claims] 1. A liquid crystal is sealed between a pair of substrates, pixel electrodes arranged in a matrix on the one substrate, a thin film transistor formed in close proximity to the pixel electrode, and a source electrode of the thin film transistor. A liquid crystal display device having a signal wiring connected to the scanning line and a scanning wiring connected to the gate electrode of the thin film transistor, and electrically connected to both the signal wiring and the scanning wiring on the inner surface of the substrate. A liquid crystal, characterized in that a first conductive thin film is formed on a non-exposed portion, and a second conductive thin film is formed on the first conductive thin film so as to overlap the pattern of the first conductive thin film via an insulating layer. Display device.