JPH10311988A - Liquid crystal display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the liquid crystal display device and its driving method which improve the display quality by eliminating a light shield defect due to the gap between a pixel and peripheral OCB(on-chip black) formed on a liquid crystal display device in contact OCB structure. SOLUTION: On a driving substrate 1, a pixel array part 2, a dummy pixel part 100, TFTs 10, 102, and 11 formed at a peripheral part 3, a 1st inter-layer insulating film 12 covering the TFTs 10, 102, and 11, a wiring electrode 13, and a 2nd inter-layer insulating film 14 are formed. On the TFT 102, a dummy pixel OCB 103 and dummy ITO 101 are formed extending up to a peripheral OCB 8 area, and the dummy ITO 101 is made black to shield the pixel array part 2 and peripheral part 3 from light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device represented by an active matrix type liquid crystal panel and the like, and a driving method thereof. It is about structure.

[0002]

2. Description of the Related Art First, a conventional liquid crystal display device will be briefly described with reference to FIG. FIG. 4 is a schematic plan view showing an example of a conventional liquid crystal display device.

A driving substrate 1 of a conventional liquid crystal display device as shown in FIG. 4 is generally constituted by a pixel array section 2, a peripheral section 3 operating the pixel array section 2, and an external connection terminal group 4. The pixel array unit 2 includes a thin film transistor (Thin Film T).
(ransistor: details will be described later) Pixel OCB formed on
(On Chip Black: hatched portion in the figure) ITO (Indium-Tin Oxid
e: transparent electrode) 7 is formed.

The peripheral portion 3 includes a horizontal / vertical drive circuit and a compensation circuit (not shown), and a peripheral OCB 8 for preventing light leakage in a portion other than the transparent pixel electrode and improving image quality.
(The same hatched portion) is formed. The external connection terminal group 4 includes a scanning line X connected to a vertical drive circuit, a Cs line W connected to a counter electrode (common electrode), and a signal line Y connected to a horizontal drive circuit and a compensation circuit. . The scanning lines X and the signal lines Y extend to the pixel array unit 2 and are connected to the thin film transistors of the pixel array unit 2. The compensation circuit is configured to supply a precharge signal when a video signal is applied to the thin film transistor, for example.

[0005] The cross-sectional structure of the driving substrate of the liquid crystal display device will be described with reference to the cross-sectional view of FIG. FIG. 5 is a sectional view taken along line AA in FIG.

The prior art liquid crystal display device shown in FIG.
A TFT 10 for driving each pixel electrode and a TFT 11 for forming a peripheral portion 3 are formed on a drive substrate 1 made of quartz glass or the like by substantially the same process. TFT10, 1
A first interlayer insulating film 1 covering the TFTs 10 and 11
2. Patterned and formed on the TFT 10
1, a wiring electrode 13 of Al (aluminum) or the like connected to
A second interlayer insulating film 14 covering the wiring electrodes 13 is formed, and the upper portion thereof is further covered with a planarizing film 15.

A pixel OCB5 for the purpose of shielding light is formed of, for example, Al, Ti, Mo or the like above the TFT 10 of the pixel array section 2, and a peripheral OCB8 is formed over the peripheral section 3 above the TFT11. Further, a TFT is connected to the wiring electrode 13 of the pixel array section 2 through the contact 6.
An ITO 7 electrically connected to 10 is formed by patterning. The pixel OCB5 is set to the same potential as ITO7,
Such a structure is called a contact OCB structure.

As is well known, a pixel potential is applied to the pixel OCB5 formed in the pixel array section 2, and the influence of the applied potential of the pixel array section 2 is applied to the peripheral OCB8 formed in the peripheral section 3. In order not to receive the potential, the common electrode and the ground (GND) potential of the opposite electrode are grounded. Therefore, the pixels OC having different potentials as described above
A gap B (see FIGS. 4 and 5) between the peripheral OCB and the pixel OCB is inevitably formed between B5 and the peripheral OCB 8, and light leakage due to the gap B between the peripheral OCB and the pixel OCB is caused. There are problems that occur.

In order to solve such a problem, in a conventional liquid crystal display device, as shown in FIG.
To the gap B between the peripheral OCB and the pixel OCB,
The peripheral OCB and the pixel O depend on the pixel potential applied to O7.
The gap B of the CB is shielded from light.

However, in such a conventional light-shielding method in the liquid crystal display device, when the ITO 7 located at the upper and lower ends of the liquid crystal display device displays black, the gap B between the peripheral OCB and the pixel OCB is also shielded at the same time. When the ITO 7 is displayed in white, the gap B is not shielded from light, so it is difficult to say that the gap B is a complete light shielding method. Further, in the structure of the conventional liquid crystal display device, a capacitance difference occurs between the pixels formed at the upper and lower ends of the liquid crystal display device and the pixels formed at the center of the pixel array unit 2, and the display of the liquid crystal display device is not performed. There is a problem that the uniformity in the state is deteriorated.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to solve the problem of the contact OC.
Provided is a liquid crystal display device and a method of driving the liquid crystal display device, which improve display quality by improving a light blocking defect caused by a gap between a pixel and a peripheral on-chip black mask inevitably formed in a liquid crystal display device having a B structure. That is.

[0012]

In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the liquid crystal display device of the present invention is divided into a pixel array portion in which pixel electrodes are arranged in a matrix and a peripheral portion including a peripheral circuit that operates the pixel array portion. Pixel light-shielding layer (so-called contact-on-chip black mask structure) patterned so that
And a driving substrate having a peripheral circuit light-shielding layer fixed at a predetermined potential and formed in a peripheral portion, so as to cover the peripheral circuit light-shielding layer between the pixel array portion and the peripheral portion. A dummy pixel electrode was formed, and a black signal supply line for applying a black signal to the dummy pixel electrode was formed. That is, since the pixel array portion and the peripheral portion are separated by the dummy pixel electrode, for example, no capacitance difference occurs between the pixel electrodes at the upper and lower ends of the liquid crystal display device and the pixel electrode at the central portion. Deterioration of uniformity in the display state of the display device can be prevented.

According to the driving method of the liquid crystal display device of the present invention having the above structure, a black signal is applied to the dummy pixel electrode formed between the pixel array portion and the peripheral portion so as to cover the peripheral circuit light-shielding layer for each vertical blanking interval. By displaying the dummy pixel electrode in black, light is shielded between the pixel array portion and the peripheral portion. This eliminates light leakage mainly due to the gap between the pixel array section and the peripheral section.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

First, the configuration of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 1 is a schematic plan view showing one example of the liquid crystal display device of the present invention. Note that portions common to those described in the related art are denoted by the same reference numerals.

A driving substrate 1 of a liquid crystal display device of the present invention as shown in FIG. 1 includes a pixel array portion 2, and a feature of the present invention is a dummy pixel portion 100 formed at the upper and lower ends of the liquid crystal display device. It is roughly composed of a peripheral part 3 and an external connection terminal group 4.

The pixel array section 2 has a thin film transistor (T
FT) Pixel OCB5 and contact 6 formed on
An ITO 7 serving as a pixel electrode is formed through the substrate. In the dummy pixel section 100, a dummy ITO 101 connected to a thin film transistor (TFT) via a contact 6 is formed so as to cover a gap B between the peripheral OCB and the pixel OCB. The dummy ITO 101 performs black display by a driving method described later. In the peripheral portion 3, in addition to a horizontal / vertical drive circuit and a compensation circuit (not shown), a peripheral OCB 8 for preventing light leakage in a portion other than the transparent pixel electrode is formed.

The external connection terminal group 4 includes a scanning line X connected to a vertical drive circuit, a Cs line W connected to a common electrode (common electrode), a signal line Y connected to a horizontal drive circuit and a compensation circuit, And a gate line Z dedicated to black signal writing for applying a black signal to the dummy pixel section 100.
The scanning lines X, the signal lines Y, and the gate lines dedicated to black signal writing Z extend to the pixel array unit 2 and are connected to the thin film transistors of the pixel array unit 2.

The sectional structure of the driving board of the present invention will be described with reference to FIG. FIG. 2 is a sectional view taken along the line CC in FIG.
It is sectional drawing on a line.

In the liquid crystal display device of the present invention shown in FIG. 2, the TFT 1 formed on the drive substrate 1 in the pixel array portion 2, the dummy pixel portion 100 and the peripheral portion 3 by the same process.
0, 102, 11; a first interlayer insulating film 12 covering the TFTs 10, 102, 11; a wiring electrode 13 patterned and formed thereon and connected to the TFTs 10, 102, 11; An insulating film 14 is formed. A pixel OCB5 for shielding light and a dummy pixel OC are provided above the TFTs 10, 102 and 11.
B103 and peripheral OCB8 are Ti, Mo, W, and C, respectively.
The upper portion is covered with a flattening film 15.

The wiring electrode 13 of the pixel array section 2 is patterned and formed with an ITO 7 that is electrically connected to the drain D of the TFT 10 via the contact 6.
A dummy ITO 101 electrically connected to the TFT 10 via the contact 6 is formed on the wiring electrode 13 extending to a region covering the gap B between the peripheral OCB and the pixel OCB.

Next, a method of driving the liquid crystal display device of the present invention will be described with reference to FIGS. 3A and 3B are diagrams showing a liquid crystal display device of the present invention, wherein FIG. 3A is a circuit diagram showing an internal configuration, and FIG. 3B is a timing chart illustrating a driving method.

The internal structure of this liquid crystal display device is shown in FIG.
As shown in (a), a horizontal switch (hereinafter simply referred to as “HSW”) 20 connected to an H shift register (not shown), and a pixel array unit 2 excluding the dummy pixel unit 100
And a precharge switch (referred to as “PSW” in the figure) 22 connected to a compensation circuit (not shown).

The horizontal switch (HSW) 20 has a signal line Y
Are connected, and the buffer circuit 23 is
, And a scanning line X is connected to the V shift register 21 via a buffer circuit 23. The intersections of the signal lines X, the scanning lines Y, and the gate lines Z dedicated to black signal writing are arranged in a matrix, and the TFTs 24 are provided at the intersections.

Then, a V blanking period (FIG. 3B)
), A bar BLK pulse is supplied to the black signal writing-dedicated gate line Z of the dummy pixel portion 100,
A pre-charge (PCG) pulse is supplied to the pre-charge switch (PSW) 22 to turn it on at the same time,
Normally, a black signal level is applied from a black signal supply line U to which a precharge signal or the like is applied, so that the dummy pixel unit 100 performs black display. Thereby, the dummy ITO formed so as to cover the gap B (see FIG. 2) between the peripheral OCB and the pixel OCB.
101 is displayed in black, the dummy pixel portion 100 is completely shielded from light, and light leakage mainly due to the gap B between the peripheral OCB and the pixel OCB is eliminated. The V shift register 21 connected to the pixel array section 2 generates a selection pulse every one horizontal period, and performs a conventionally known operation of sequentially selecting each scanning line X via the buffer circuit 23.

In the structure of the liquid crystal display device of the present invention,
Since the dummy ITOs 101 are formed in the dummy pixel units 100 provided at the upper and lower ends of the liquid crystal display device, no capacitance difference occurs between the pixels at the upper and lower ends of the pixel array unit 2 and the pixels at the central part. Deterioration of uniformity in the display state can be prevented.

The present invention is not limited to the above embodiment,
Various embodiments can be employed. For example, in this embodiment, an example in which the black matrix is formed only on the driving substrate is described. However, a black mask may be formed on the opposing substrate by a predetermined method and used together with the driving substrate. In addition, it goes without saying that the present invention can be developed in various forms without being limited to the above-described embodiments.

[0028]

As described above, in the liquid crystal display device of the present invention, in particular, in a liquid crystal display device having a so-called contact on-chip black mask structure in which an on-chip black mask is formed on a thin film transistor for light shielding, and a method of driving the same, Dummy pixel portions are formed at the upper and lower ends of the liquid crystal display device, and the dummy pixel portions are displayed in black to shield light between the pixel array portion and the peripheral portion. Light leakage, which is the main cause, is completely eliminated.

In the structure of the liquid crystal display device of the present invention,
Since the dummy pixel electrodes are formed in the dummy pixel portions provided at the upper and lower ends of the liquid crystal display device, no capacitance difference occurs between the pixels at the upper and lower ends of the liquid crystal display device and the pixels at the central portion. Can be prevented from deteriorating in the display state of.

[Brief description of the drawings]

FIG. 1 is a schematic plan view illustrating an example of a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view taken along line CC in FIG.

FIG. 3 is a view showing a liquid crystal display device of the present invention;
FIG. 3A is a circuit diagram illustrating an internal configuration, and FIG. 3B is a timing chart illustrating a driving method.

FIG. 4 is a schematic plan view showing an example of a conventional liquid crystal display device.

FIG. 5 is a sectional view taken along line AA in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drive board, 2 ... Pixel array part, 3 ... Peripheral part, 4 ... External connection terminal group, 5 ... Pixel OCB, 6 ... Contact, 7 ...
ITO, 8 ... OCB around, 10, 11, 102, 24 ...
TFT, 12: first interlayer insulating film, 13: wiring electrode, 14
... Second interlayer insulating film, 15 flattening film, 20 horizontal switch, 21 V shift register, 22 precharge switch, 23 buffer circuit, 100 dummy pixel section, 1
01: Dummy ITO, 103: Dummy pixel OCB

Claims (2)

[Claims] 1. A pixel array section in which pixel electrodes are arranged in a matrix, and a peripheral section including peripheral circuits operating the pixel array section, wherein the pixel array section has the same potential as the pixel electrodes. A liquid crystal display device comprising a drive substrate having a pixel light-shielding layer patterned as described above and a peripheral circuit light-shielding layer patterned at the peripheral portion and fixed at a predetermined potential, comprising: A liquid crystal display device, further comprising a dummy pixel electrode covering the peripheral circuit light-shielding layer, and a black signal supply line for applying a black signal to the dummy pixel electrode. 2. A pixel array section in which pixel electrodes are arranged in a matrix, and a peripheral section including a peripheral circuit operating the pixel array section, wherein the pixel array section has the same potential as the pixel electrodes. A method for driving a liquid crystal display device including a driving substrate having a pixel light-shielding layer patterned and formed as described above, and a peripheral circuit light-shielding layer patterned and formed at the peripheral portion and fixed at a predetermined potential. Forming a dummy pixel electrode covering the peripheral circuit light-shielding layer between peripheral portions, and applying a black signal to the dummy pixel electrode for each vertical blanking interval to shield the pixel array portion and the peripheral portion from each other. Characteristic driving method of a liquid crystal display device.