JPH11174490A - Liquid crystal display element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the numerical aperture of a liquid crystal display element by sharing two adjacent pixel electrodes existing in a wide range by each of common electrodes. SOLUTION: A pair of sub-injection signal lines 20a, 20b constituting each injection signal line 20 are separated from a pair of sub-injection signal lins 20c, 20d with a wide interval. The signal lines 20a, 20c are arrayed so as to be adjacent to another pair of sub-injection signal lines 20b, 20d with small intervals. The signal lines 20a, 20b and a pair of display signal lines 50a, 50b restrict a 1st range 80, i.e., a narrow range and the signal lines 20b, 20c and the signal lines 50a, 50b restrict a 2nd range, i.e., a wide range. Many pixel electrodes are formed in the 2nd range so that two pixel electrodes are arrayed in the 2nd range. An H-shaped common electrode 100 is arrayed in the wide range 90 and shares a pair of pixel electrodes 40a, 40b, which are driven independently of the injection signal lines 20 and the display signal lines 50.

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, and more particularly, to an active liquid crystal display device capable of improving the aperture ratio and image quality of a liquid crystal display device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In order to meet the demand for a personal space-saving display element serving as an interface between a human and a computer, a liquid crystal display is used.
(LCD), plasma display panel (PDP) and electrofluorescence (elect
Various forms of flat screen or flat panel displays, such as roluminescent displays, to replace conventional displays, especially cathode ray tubes (CRTs) that are relatively large and protruding in shape. Has been developed.

A liquid crystal display device has an electrooptic property of a liquid crystal in which the molecular arrangement of the liquid crystal is changed by an electric field.
Using y), it has a simple matrix form and an active matrix form. In particular, active matrix LCDs use a combination of liquid crystal technology and semiconductor technology, and are perceived as having sharper images than CRT displays.

An active matrix liquid crystal display device controls each pixel by using switching characteristics of an active element having a non-linear characteristic for each of a large number of pixels forming a matrix array. As the active element, a thin film transistor having three terminals (hereinafter, referred to as TFT) is usually used,
Also, a thin film diode (TFD), for example, a metal insulated metal thin film diode having two terminals is used.

In order to obtain uniformity of an image displayed on an active matrix liquid crystal display, a writing operation is performed.
At the time of ration, the voltage of the signal applied via the display signal line should be kept constant for a limited time before receiving the next signal. To achieve this effect, a storage capacitor is formed for each pixel. In order to improve the image quality of the display, the storage capacitor is formed in parallel with the liquid crystal cell. Here, the storage capacitor is usually formed as an independent wire form separated from the injection signal line, and the capacitor electrode for forming the storage capacitance in the independent wire form is used for forming the injection signal line during the injection signal line forming process. It is formed at the same time as the line.

FIG. 3 shows a pixel layout of a conventional active matrix LCD on which independent wire type storage capacitors are formed. As shown, a large number of injection signal lines 2 and display signal lines 5 are arranged in a matrix on the lower glass substrate 1, and pixels are formed in an area surrounded by these two types of signal lines 2, 5. And each pixel has ITO
The pixel electrodes 4 which are transparent electrode materials such as (Indium Tin Oxide) are arranged. Also, a TFT is provided on the injection signal line 2.
The semiconductor layers 3 each serving as a channel are formed. Each semiconductor layer 3 is connected to the display signal line 5 by the drain electrode 6 and connected to the pixel electrode 4 by the source electrode 7.
Accordingly, the driving of each pixel arranged in a matrix is independently controlled by the TFT functioning as a switching element.

Each pixel is separated from each injection signal line 2 by a predetermined distance, and an independent wire-shaped storage capacitor electrode 10 is formed in parallel with each injection signal line 2. Capacitor electrode 10
Is formed from an opaque conductive metal, such as chromium, tantalum, aluminum, or molybdenum.

However, as described above, an active matrix LCD having an independent wire-shaped storage capacitor is:
Since a capacitor electrode made of an opaque metal is formed in each pixel, the aperture ratio of the LCD is reduced.

Recently, in order to improve the aperture ratio of the LCD, the distance between the pixel electrode and the display signal line, the distance between the injection signal lines, and the distance between the display signal lines are minimized. Since it is designed, a voltage change of a signal applied to the injection signal line and the display signal line causes a parasitic capacitance (parasitic) between the injection signal line and the display signal line and the pixel electrode.
capacitance), and as a result
There is a problem that ce spots and crosstalking occur.

Also, in order to realize the colorization of the active matrix LCD, the lower substrate having the above structure is combined with the upper substrate having the color filters formed thereon.
g) It is difficult to accurately align pixel electrodes and color filters during the process. Accordingly, when the pixel electrodes are not correctly aligned with the corresponding color filters, light leakage occurs, and in order to prevent light leakage, a black matrix for separating the color filters on the upper substrate is used. Increasing the width causes a problem that the aperture ratio of the LCD decreases.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an LCD capable of improving the aperture ratio and a method of manufacturing the same.

It is another object of the present invention to provide an LCD in which a light-shielding layer is formed in an area between a display signal line and a pixel electrode to prevent light leakage, and a method of manufacturing the same.

Still another object of the present invention is to make it possible to secure a larger distance between the display signal line and the pixel electrode than in the conventional case, thereby providing a parasitic capacitance between the pixel electrode and the display signal line. It is an object of the present invention to provide an LCD and a method of manufacturing the same, which can prevent the occurrence of the bleeding and suppress the luminance stain and crosstalk due to the parasitic capacitance.

[0014]

According to the present invention, there is provided a liquid crystal display device comprising: a transparent substrate; a plurality of injection signal lines arranged on the transparent substrate; and the plurality of injection signal lines. , And each injection signal line is composed of a pair of sub-injection signal lines. The injection signal lines are arranged such that a plurality of pairs of sub-injection signal lines are repeated at a wide interval from each other, and one of the pair of sub-injection signal lines is adjacent to the other with a narrow interval. The pair of sub-injection signal lines and the pair of display signal lines define a first area (narrow area), and one sub-injection signal line of the pair of sub-injection signal lines One sub-injection signal line of the next pair of sub-injection signal lines facing it and a pair of display signal lines are a number of injection signals defining a second area (wide area) wider than the first area. And a plurality of display signal lines, and a plurality of pixel electrodes made of a transparent conductive material such as ITO arranged two by two in each of the second areas, each corresponding to a corresponding one of the display signal lines. A second section connected to a signal line and a corresponding electrode in the pixel electrode; And a large number of switching elements corresponding to

One inverted staggered thin film transistor provided corresponding to one of the pair of sub-injection signal lines used as a gate electrode is formed as a switching element on one upper surface of the sub-injection signal line, An electric signal is applied to one pixel electrode in one second region through a display signal line. In the same manner, the reverse staggered thin film transistor using the other one of the pair of sub-injection signal lines is formed on another upper surface of the sub-injection signal line as a switching element, and the one through the display signal line. An electric signal is applied to one pixel electrode in another second region adjacent to one second region.

Further, in the liquid crystal display device, a common electrode having an "H" character shape is arranged in a wide area, and corresponds to a pair of pixel electrodes. The common electrode is superimposed on the periphery of the two pixel electrodes via an insulating layer except for the periphery connected to the TFT, and forms a storage capacitor therebetween. Side surfaces of the two outer shells of the common electrode extend at least to a display signal line to prevent light leakage. The common electrode is connected to an adjacent common electrode through contact portions in parallel with the injection signal lines on both sides. The common electrode is driven independently of the injection signal line and the display signal line.

According to the present invention, the aperture ratio is increased by configuring the common electrode to share two adjacent pixel electrodes in one wide area. Also, the common electrode made of an opaque substance has an "H" character shape, and both sides facing each other extend to the display signal line without overlapping with the pixel electrode, thereby blocking light between the display signal line and the pixel electrode. L acts as a layer
Light leakage of the CD is prevented, and it is not necessary to extend the black matrix of the upper substrate to a portion corresponding to the periphery of the pixel electrode of the lower substrate in order to prevent light leakage.

Further, according to the present invention, each common electrode shares two pixel electrodes in each pixel region, so that LC
Since the aperture ratio of D increases, the distance between the pixel electrode and the display signal line becomes wider than in the conventional device. Therefore, the parasitic capacitance between the pixel electrode and the display signal line is greatly reduced, and thus, the change in the voltage applied to the display signal line causes
LCD defects due to luminance spots and crosstalk generated during driving are prevented.

[0019]

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a large number of injection signal lines 20 and a large number of display signal lines 50 crossing the injection signal lines 20 are arranged on a transparent substrate 200. Each injection signal line 20 is composed of a pair of auxiliary injection signal lines. Also, the injection signal lines are arranged such that a number of pairs of sub-injection signal lines are repeated at a wide interval from each other. For example, the first auxiliary injection signal line 20a and the second auxiliary injection signal line 20b constitute a pair of injection signal lines. The third auxiliary injection signal line 20c and the fourth auxiliary injection signal line 20d form another pair of injection signal lines.
The pair of auxiliary injection signal lines 20a and 20b are separated from the pair of auxiliary injection signal lines 20c and 20d at a wide interval. One 20a (or 20c) in a pair of sub-injection signal lines, another 20b in a pair of sub-injection signal lines
(Or 20d) so as to be adjacent to each other with a small interval. A pair of auxiliary injection signal lines 20a and 20b
Is a pair of the display signal lines 50a and 50b and the first area 80.
Or a narrow area. One 20b of the pair of sub-injection signal lines, one 20c of the next pair of sub-injection signal lines facing it, and the display signal lines 50a and 50b define the second area 90, that is, the wide area. I do.

The plurality of pixel electrodes are formed in the second area such that two pixel electrodes are arranged in each second area. For example, the two pixel electrodes 40 a and 40 b are arranged in the second area 90 in parallel with the display signal line 50 at predetermined intervals. Each pixel electrode is formed from a transparent conductive material such as ITO.

A number of switching elements are formed on injection signal lines for applying electric signals to the pixel electrodes. As shown in FIG. 3, the two thin film transistors 110a and 110b as switching elements correspond to the second area 90 to connect the display signal line 50a to the two pixel electrodes 40a and 40b. On the other hand, an inversely staggered TFT using the sub-injection signal line 20b as a gate electrode is used as a switching element for applying an electric signal to the pixel electrode 40a through the display signal line 50a.
Formed on top. In the same manner, the secondary injection signal line 20 is used.
a is used as a gate electrode, and an inversely staggered TFT is used as the display signal line 5.
It is formed on the sub-injection signal line 20a as a switching element for applying an electric signal to the pixel electrode 40c through Oa. Instead of a reverse staggered thin film transistor, a thin film diode (TFD), for example, a metal-excellent metal (MIM) diode having two terminals, is used. Here, the portion 60a protruding from the display signal line 50a serves as a common drain electrode of the two thin film transistors 110a and 110c. The common drain electrode corresponds to the pixel electrode 40a and the pixel electrode 40c in the wide area above the narrow area 80. In a similar manner, the portion 60b protruding from the display signal line 50a is
The common drain electrodes 10b and 110d are formed.

The "H" character-shaped common electrodes 100 are arranged in a wide area 90 and share a pair of pixel electrodes 40a and 40b. As shown in FIG.
Are two pixel electrodes 40 connected to two thin film transistors 110a and 110b to form a storage capacitance type capacitor between the pixel electrodes 40a and 40b.
The peripheral portions 100a, 100b, 100c, 100e, 100f of the two pixel electrodes 40a and 40b excluding the peripheral portions 100d and 100h of a and 40b.
And 100 g along with the pixel electrode. The two side portions 100i and 100j of the electrode 100 extend at least to the display signal lines 50a and 50b, respectively, to prevent light leakage.

As shown in FIG. 1, each of the "H" character-shaped common electrodes 100 includes connecting portions 100k and 100l.
Are connected in parallel with the injection signal line in the left-right direction with the adjacent common electrode of the letter "H". "H" letter-shaped electrode 10
Each of the 0s is driven independently of the injection signal line 20 and the display signal line 50.

Hereinafter, one embodiment of a method of manufacturing an LCD according to the present invention will be described with reference to FIGS.

As shown in FIG. 2, first, the transparent substrate 2
A first metal layer is deposited on the first metal layer to a thickness of 4000 ° or less. Then, the injection signal line 20 and the common electrode 100 are formed by patterning the first metal layer. At this time, connecting portions 100k and 100I are also formed to connect between two adjacent common electrodes.

Here, as shown in FIG. 2, the injection signal line 20 includes a plurality of pairs of sub-injection signal lines. The injection signal lines 20 are arranged such that a number of pairs of sub-injection signal lines are repeated with a large interval between them, and one 20a of the two sub-injection signal lines in the pair is One 20b is arranged so as to be adjacent to each other with a small space therebetween. Each of the common electrodes 100 has the form of an “H” character. Each of the electrodes having the “H” character form is connected to the left and right in parallel with the injection signal line by the adjacent “H” character form common electrode and the connection portions 100k and 100l. Since the common electrode 100 serves as a light blocking layer, the first metal layer is formed of an opaque metal or alloy such as chromium, tantalum, aluminum, molytantalum, and molytungsten.

Subsequently, an insulating layer 110 is formed at a predetermined thickness on the above-mentioned structure using a chemical vapor deposition method, and then a region for forming a switching element on the injection signal line 20 is defined. Then, a semiconductor layer 30 of amorphous silicon serving as a channel of the thin film transistor is formed on the surface of the insulating layer 110.

After that, a transparent conductive thin film such as ITO is deposited on these structures and patterned, and two pixel electrodes 40a and 40 are formed in each second region to be formed later.
b is formed. As shown in FIG. 2, the two pixel electrodes 40a and 40b correspond to the common electrode 100, and the two pixel electrodes 40a and 40b have their peripheral portions 100a and 100b.
In b, 100c, 100e, 100f, and 100g, the common electrode 100 and the common electrode 100 are overlapped via the insulating layer 110.

Next, an opaque conductive metal is vapor-deposited on the structure formed in the above step, and then patterned to form an injection signal line 2.
A display signal line crossing zero (not shown in FIG. 2);
Drain electrodes 60a and 60b and source electrode 70a,
70b, 70c and 70d are formed simultaneously. Here, as shown in FIG. 1, each of the protruding portions 60a and 60b from the display signal line 50a is connected to a pair of sub-injection signal lines 20a and 20b, or a pair of thin film transistors 110c and 20c formed on 20c and 20d. It corresponds to 110a or 110b and 110d.

[0031]

According to the embodiment of the present invention, each of the common electrodes shares two adjacent pixel electrodes in a wide area, so that the aperture ratio of the liquid crystal display device is improved. In addition, the common electrode of the opaque metal has an "H" character shape, and two side portions of the common electrode which do not overlap with the pixel electrode are respectively extended to the display signal line, so that light is blocked between the display signal line and the pixel electrode. Since it functions as a layer, light leakage of the LCD is eliminated, and it is not necessary to extend the black matrix on the upper substrate to a region corresponding to a peripheral portion of the pixel electrode in order to prevent light leakage.

Further, according to the present invention, since two pixel electrodes correspond to one common electrode, LC
The aperture ratio of D can be improved, and a certain gap wider than before can be secured between the pixel electrode and the display signal line. Accordingly, since the parasitic capacitance generated between the pixel electrode and the display signal line can be suppressed, it is possible to prevent the deterioration of the image quality of the LCD due to the luminance spot and the crosstalk.

On the other hand, although specific embodiments of the present invention have been shown and described herein, modifications and variations may be made by those skilled in the art. It is therefore intended that the following claims be interpreted as including all alterations and modifications as fall within the true concept of the invention.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating an active matrix type LCD according to the present invention.

FIG. 2 is a cross-sectional view taken along a line III-III ′ of FIG. 1 for explaining a method of manufacturing an active matrix LCD according to the present invention.

FIG. 3 is a plan view illustrating an active matrix LCD according to the related art.

[Explanation of symbols]

 20, 20a, 20b, 20c, 20d Injection signal line 30 Semiconductor layer 40a, 40b, 40c Pixel electrode 50, 50a, 50b Display signal line 80 First section 90 Second section 100 Common electrode

Claims (14)

[Claims] A plurality of injection signal lines arranged on a surface of the transparent substrate, each of the plurality of injection signal lines including a pair of sub-injection signal lines; The line pairs are arranged to be spaced apart and repeated at a first length, wherein one of the pair of sub-injection signal lines is shorter than the other of the pair of sub-injection signal lines and the first length. A plurality of display signal lines intersecting with the plurality of injection signal lines and arranged on the surface of the transparent substrate, and a pair of the display signal lines is a pair of the sub-injection signals. The first region is limited together with the line, the upper signal line of the pair of sub-injection signal lines, the lower signal line of the pair of sub-injection signal lines next to the pair of sub-injection signal lines, and the pair of the display signal lines. Defines a second area wider than the first area, and two are arranged for each second area. A plurality of pixel electrodes, each of which is connected to a corresponding one of the display signal lines and a corresponding one of the pixel electrodes, and a plurality of switching elements corresponding to the second region; A plurality of injections are arranged in the second region, each being shared by the two pixel electrodes in each said second region, so as to face two corresponding pixel electrodes in the region. A liquid crystal display device comprising a signal line, a number of display signal lines, and a number of common electrodes driven independently. 2. The liquid crystal display device according to claim 1, wherein one common electrode of the second region further includes a portion connected to a common electrode of an adjacent second region. 3. Each of the plurality of common electrodes is “H”.
In the form of a letter, wherein each of said common electrodes is respectively connected to a switching element to form a storage capacitance type capacitor with two corresponding pixel electrodes;
2. The liquid crystal display device according to claim 1, wherein the liquid crystal display element overlaps the edge portions of the two pixel electrodes except for the edge portions of the corresponding two pixel electrodes. 4. The liquid crystal display device according to claim 3, wherein two opposed outermost side surfaces of the common electrode extend at least to the display signal line. 5. The two switching elements are formed on a pair of sub-injection signal lines, and the two switching elements serve as two drain electrodes and have one common protrusion from a corresponding display signal line. 2. The liquid crystal display device according to claim 1, comprising a portion. 6. The liquid crystal display device according to claim 1, wherein the common electrode and the injection signal line are formed of the same material. 7. The liquid crystal display device according to claim 6, wherein the material is at least one opaque conductive metal or alloy selected from the group consisting of aluminum, chromium, molybdenum and molybdenum. 8. The method of manufacturing a liquid crystal display device according to claim 1, further comprising: forming a first metal layer on the transparent substrate; patterning the first metal layer to form the injection signal line; Forming a common electrode in the two regions; forming an insulator layer and a semiconductor layer continuously on the surface of the resulting structure; and forming the semiconductor layer around a portion of the injection signal line. Patterning the semiconductor layer so as to remain only, forming a transparent conductive layer on the surface of the resulting structure, and forming a pixel electrode by patterning the transparent conductive layer. Forming a second metal layer on the resultant structure, and patterning the second metal layer to simultaneously form a plurality of display signal lines and a source / drain of a switching element on the semiconductor layer. Forming a liquid crystal display element. 9. The step of forming the injection signal line and the common electrode, wherein the common electrode of the one second area is connected to the common electrode of another second area adjacent to the one second area. 9. The connecting part is formed simultaneously.
The manufacturing method of the liquid crystal display element described in. 10. The method according to claim 8, wherein two opposed outermost side surfaces of the common electrode extend at least to the display signal line. 11. Each of the plurality of common electrodes is in the form of an “H” character, and each of the common electrodes forms a storage capacitance type capacitor with two corresponding pixel electrodes. 9. The method according to claim 8, wherein the overlapping is performed along an edge of the corresponding two pixel electrodes. 12. The two switching elements are formed on the pair of sub-injection signal lines, and the two switching elements have one common electrode protruding from a corresponding display signal line and serving as a drain electrode. 9. The method for manufacturing a liquid crystal display element according to claim 8, wherein: 13. The method according to claim 8, wherein the common electrode and the injection signal line are made of the same material. 14. The liquid crystal according to claim 13, wherein the first metal layer is at least one opaque conductive metal or alloy selected from the group consisting of aluminum, chromium, molybdenum and molybdenum. A method for manufacturing a display element.