JPH10333182A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a local decrease in the charge holding rate of liquid crystal which appears with driving hours owing to ionic impurities of a resticking orientation film foreign body based upon a rubbing type orienting process without increasing the area of a screen frame as to an orthogonal pixel array type liquid crystal display device. SOLUTION: The liquid crystal is charged between a couple of substrates. On the 1st substrate, gate wires 14 and source wires 13 are arranged crossing each other matrix, and at respective intersections of those gate wires 14 and source wires 13, display pixels 11 consisting of thin film transistors where pixel electrodes 19 are connected are arrayed orthogonally. On the 2nd substrate, a counter electrode formed of a transparent conductive film is arranged. Here, a non-display dummy pixel pattern 20 which is shifted in pixel array pitch from the display pixels 11 is arranged by at least one row or column adjacently to the display pixels 11 on the 1st substrate in the row or column direction.

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 a so-called active matrix type liquid crystal display device for driving liquid crystal using a non-linear element.
The present invention relates to a liquid crystal display device characterized by the structure of the thin film transistor array substrate.

[0002]

2. Description of the Related Art In recent years, based on advances in fine processing technology, material technology, high-density packaging technology, and the rapid spread of multimedia equipment, a wide range of screen sizes and A
In various applications such as V, OA, in-vehicle, and information communication, the ratio occupied by the liquid crystal display device is rapidly expanding. Liquid crystal display devices have attracted attention in the electronics industry as a key device replacing CRTs. Under such circumstances,
By further evolving the advantages of the thin and light weight characteristic of liquid crystal display devices, product areas (for example, from A4 and B5 size notebook computers to sub-notebook computers, DIN standard compliant car navigation systems, monitors Body video movies, pen-type personal digital assistants, etc.).

In the field of the liquid crystal display device, in particular, the development of a technique of how to obtain a large screen with respect to the size of the device has been developed. Is urgently needed.

First, an outline of a thin film transistor array substrate of a conventional active matrix type liquid crystal display device will be described with reference to the drawings. FIG. 3 shows a schematic diagram thereof.
Here, 1 is a mother glass substrate, and 2 is an effective area of a thin film transistor array substrate necessary for a liquid crystal display device. Here, a case of multiple chamfering in which effective areas for two panels are arranged is shown. Reference numerals 3a and 3b denote unit effective areas for one panel, respectively, and will be referred to as chips. Reference numeral 4 denotes a region required for transporting the mother glass substrate 1 in a manufacturing process, forming a recognition pattern, and the like, and is referred to as a mother glass frame.

Effective area 2 of thin film transistor array substrate
A display liquid crystal cell region 5 in which thin film transistors, which are active elements for switching liquid crystal, are arranged in a matrix is disposed in a central portion on the inside. Around the display liquid crystal cell area 5, a mounting area 6 for the driving driver is provided.
A seal region 7 for attaching a counter substrate and enclosing and fixing a liquid crystal material in a display liquid crystal cell region 5, and a non-display liquid crystal cell region 8 sandwiched between the display liquid crystal cell region 5 and the seal region 7.
Are provided. The non-display liquid crystal cell area 8 has a margin area for preventing the seal area 7 from overlapping with the display screen area 5 and causing display failure even if the position of the seal area 7 is shifted due to manufacturing variations. It is. 9
Is an area in which the seal area 7 and the non-display liquid crystal cell area 5 are combined, and is referred to as a screen frame here. 10 is
The combined area of the display liquid crystal cell region 5 and the non-display liquid crystal cell region 8 is referred to as a liquid crystal cell region here.

In order to use the mother glass 1 as effectively as possible, there is firstly a method of minimizing the size of the mother glass frame 4. However, since this is limited by the structure of the manufacturing equipment, a size below a certain level cannot be expected at present. The size of the mother glass frame 4 is chip 3
To take a constant value regardless of the number of chamfers a and 3b,
As the number of chamfers increases, the influence per chip is dispersed, and the influence on the chip size is not so large.

Second, if the effective area 2 of the thin film transistor array substrate is considered to be constant, the maximum chip size for each number of chamfers is determined by itself. The only way is to make 9 smaller. Further, even when the size of the display liquid crystal cell region 5 is fixed and the number of multi-panels is maximized,
It is effective to reduce the size of the chips 3a and 3b by reducing the size of the screen frame 9. Further, since the size of the screen frame 9 is substantially constant without being restricted by the size of the display liquid crystal cell region 5, the influence thereof increases as the number of chamfers increases.

[0008] Therefore, design measures are usually taken to minimize the picture frame 9. FIG. 4 is an enlarged view of the vicinity of the screen frame 9 in FIG.
Here, reference numerals 11 denote display effective pixels in the display liquid crystal cell region 5, which are arranged orthogonally. Reference numeral 12 denotes non-display dummy pixels in the non-display liquid crystal cell region 8, which are arranged orthogonally so as to extend the display effective pixels 11. 13 is a source signal wiring,
14 is a gate signal wiring. Here, the non-display dummy pixel 12 has the source signal line 1 in the same manner as the display effective pixel 11.
3 and the gate signal wiring 14 are connected, and the same driving as that of the display effective pixel 11 is performed. That is, the non-display dummy pixels 12 are usually arranged in one or more rows by repeating the same pixel pattern as the display effective pixels 11 as it is. Although there are several reasons for arranging the non-display dummy pixels 12 in this manner, the biggest reason is that there is a problem in reliability of display quality.

The problems in reliability of display quality are as follows. Usually, the alignment treatment for aligning the liquid crystal molecules in a predetermined direction is performed by using a cloth made of fiber such as rayon or nylon under a certain load to align the alignment film (polyimide resin) on the substrate in a certain direction. This is performed by a rubbing method of rubbing. However, at that time, the alignment film that has been scraped off from the substrate by friction and adhered to the cloth has re-attached to the substrate as a foreign substance, and the amount of the adhesion is obviously larger as the change in the step shape of the substrate is larger. Tend. In other words, the re-adhesion concentrates on the boundary between the area where the pixels are arranged and the wiring area. The imide bond of the alignment film foreign matter that has re-attached is broken by frictional heat during rubbing and moisture in the air,
The carboxylic acid is in a state easily separated as an ion. These diffuse into the liquid crystal over time as ionic impurities. These ionic impurities degrade the voltage holding ratio of the liquid crystal, but when they are uniformly diffused in the liquid crystal, they are not recognized as luminance unevenness in image display, and do not cause a serious problem.

However, as described above, the distribution of the reattached foreign matter is concentrated around the screen from the beginning, and uniform diffusion is impossible. Further, since these impurities have ionicity, they have a property of moving in the liquid crystal cell as the drive time elapses, and are greatly affected by a gate signal having many DC components. In other words, the ionic impurities move in a certain direction depending on the gate scanning direction, and a region where the ionic impurities are concentrated exists. The ionic impurities concentrated in this region cause a local decrease in the charge retention rate, which is observed as uneven brightness on the image display.

Therefore, in order to prevent luminance unevenness, which is a problem in the reliability of display quality, the non-display dummy pixel 12 which is normally driven is arranged in the non-display liquid crystal cell region 8 so that the ionic impurities can be prevented. The area where the rubbing foreign matter as a source is reattached is kept away from the display liquid crystal cell area 5, and the area where the ionic impurities moved by the scanning of the gate are finally concentrated is the non-display dummy pixel 12 in the non-display liquid crystal cell area 8. To be located near the gate electrode is an effective means.

[0012]

However, in the above conventional structure, the chips 3a, 3b under the same screen size are not used.
When trying to minimize the area of the screen frame 9 or to minimize the size of the picture frame 9 to increase the number of multi-panels, the sealing area 7 cannot be reduced to a certain width or less from the viewpoint of reliability. One method is to cut and reduce the cell area 8. In order to reduce the non-display liquid crystal cell region 8, in the conventional technique, the number of columns in which the non-display dummy pixels 12 are arranged is reduced, and in many cases, only a minimum of one row or one column can be arranged.

This is because, if the non-display liquid crystal cell region 8 is reduced without reducing the number of rows or columns in which the non-display dummy pixels 12 are arranged, the worst case is taken into account when manufacturing variations in the size of the seal region 7 are taken into consideration. Since the seal region 7 overlaps the non-display dummy pixel 12 and the liquid crystal itself cannot exist in the overlapped portion, the seal region 7 serves as the ionic impurity capture electrode of the non-display dummy pixel 12 described in the related art. Is lost, and it becomes impossible to prevent the occurrence of uneven brightness on the image display. Further, normally, the contact surface of the seal region 7 with the active substrate side is almost uniformly the source signal line 13 or the gate signal line 14, but a part of the contact region with the non-display dummy pixel 12 having a different level and a different surface state. This is because the contact may cause a problem of a sealing property due to a decrease in adhesion and a cause of a problem of uneven gap of a liquid crystal cell due to uneven steps.

However, even if a minimum of one row or one column of the non-display dummy pixels 12 can be arranged, if the non-display dummy pixels 12 are arranged orthogonally to the extension of the display effective pixels 11, the source signal Since the arrangement of the wiring 13 and the gate signal wiring 14 becomes substantially linear, the unevenness of the substrate becomes monotonous. That is, the coefficient of friction is reduced, and contaminants adhering to the rubbing cloth cannot be completely captured in the area of the non-display dummy pixels 12, and the remaining contaminants adhere to the area of the display effective pixels 11. is there.

The present invention has been made to solve the above-mentioned conventional problems.
An object of the present invention is to provide an effective structure of a thin film transistor array substrate of a liquid crystal display device.

[0016]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention is arranged so that a pixel array pitch is adjacent to a display pixel arranged in an orthogonal direction, and a pixel arrangement pitch of the display pixel is set in a row direction or a column direction. A non-display dummy pixel pattern shifted in the direction is arranged in at least one row or one column.

According to this, since the non-display dummy pixel pattern in which the pixel arrangement pitch is shifted in the row direction or the column direction with respect to the display pixel is arranged, it is possible to increase the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth. it can.
For this reason, even when a large non-display liquid crystal cell area cannot be secured due to a small screen frame, a non-display dummy pixel pattern that operates in the narrow area equivalently to the conventional non-display dummy pixels for several rows or columns. Can be arranged. Therefore, even if there is reattachment contamination from the rubbing cloth, they can be kept in the non-display liquid crystal cell region, and uniform and good image display characteristics can be obtained.

[0018]

According to the first aspect of the present invention, a liquid crystal is filled between a pair of substrates, and a plurality of gate wirings and source wirings crossing in a matrix are arranged on a first substrate. At the same time, at each intersection of the gate wiring and the source wiring, display pixels formed of thin film transistors connected to pixel electrodes are arranged in an orthogonal array, and on the second substrate,
In a liquid crystal display device in which a counter electrode made of a transparent conductive thin film is arranged, a non-display dummy adjacent to a display pixel on the first substrate in a row direction or a column direction and having a pixel arrangement pitch shifted from the display pixel. At least one pixel pattern
They are arranged in rows or one column.

This has the effect of increasing the coefficient of friction of the area of the non-display dummy pixels with the rubbing cloth.

According to a second aspect of the present invention, the color pattern pitch of the color filters of the second substrate is shifted in accordance with the non-display dummy pixels of the first substrate. This has the effect of increasing the friction coefficient of the color pattern in the non-display dummy pixel area on the color filter side with the rubbing cloth.

According to a third aspect of the present invention, the shift amount of the non-display dummy pixels is a half pixel pitch. According to this, similarly, there is an effect of increasing the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a schematic view showing the vicinity of a picture frame of a thin film transistor array substrate of a liquid crystal display device according to Embodiment 1 of the present invention. The liquid crystal display device of the embodiment shown in FIG. 1 has basically the same configuration as the conventional liquid crystal display device shown in FIG. Is omitted.

In FIG. 1, reference numeral 5 denotes a display liquid crystal cell area;
1 is a display effective pixel. The display effective pixel 11 is connected to the source electrode 15 connected to the source signal wiring 13, the gate electrode 16 connected to the gate signal wiring 14, the semiconductor layer 17 of the TFT, the drain electrode 18, and the drain electrode 18. And a pixel electrode 19.

Reference numeral 8 denotes a non-display liquid crystal cell area, in which non-display dummy pixels 20 are formed. This non-display dummy pixel 20 is connected to the source signal line 1 like the display effective pixel 11.
3 and the gate signal wiring 14 are connected to each other, and include a dummy source electrode 21, a dummy gate electrode 22, a dummy semiconductor layer 23, a dummy drain electrode 24, and a dummy pixel electrode 25. The non-display dummy pixel 20
The arrangement is shifted from the display effective pixels 11 by a half pixel pitch in the row direction. That is, the non-display dummy pixel 2
In the portion of 0, the source signal wiring 13 connected to the dummy source electrode 21 is bent. Here, in order to make the drive potential of the dummy pixel electrode 25 basically the same as the drive potential of the pixel electrode 19 of the display effective pixel 11, TF
The size such as the T size and the capacitance is changed by the dummy source electrode 21, the dummy gate electrode 22, the dummy semiconductor layer 23, or the like.
Also, the design parameters of the dummy drain electrode 24 and the dummy pixel electrode 25 are optimized and adjusted.

In the liquid crystal display device of the first embodiment configured as described above, even when the non-display liquid crystal cell region 8 is narrow and the number of arranged rows of the non-display dummy pixels 20 is limited,
In the portion of the non-display dummy pixel 20, the source signal line 13 connected to the dummy source electrode 21 is bent,
Since the friction coefficient changes abruptly in this portion, contaminants re-adhering from the rubbing cloth are captured in this portion, that is, outside the area of the display effective pixel 11. Therefore,
A minimum dummy area is required. This occurs when no non-display dummy pixels are arranged or when non-display dummy pixels are arranged in an orthogonal array without reducing the distance between the seal area 7 and the non-display dummy pixels 20. Display characteristics can be prevented.

In the above description, the non-display dummy pixel 2
Although the example in which the arrangement of 0s is shifted in the row direction, that is, the direction in which the number of gates is increased has been described, there may be a form in which the arrangement of 0s is shifted in the column direction, that is, the direction in which the number of source lines is increased. Also, the number of rows and the amount of shift may be freely selected as needed.

(Embodiment 2) FIG. 2 is a schematic view showing the vicinity of a picture frame of a color filter substrate in a liquid crystal display device according to Embodiment 2 of the present invention. In this embodiment, a case will be described in which non-display dummy pixels on the thin film transistor array substrate side are arranged in two rows with a half pixel pitch shift.

In FIG. 2, reference numeral 27 denotes a display color pattern, in which RGB are arranged in stripes.
A black matrix 28 is opened correspondingly. Reference numeral 29 denotes a non-display dummy color pattern, which is arranged at a half pixel pitch for each row, and RGB is arranged in a delta shape. In this non-display dummy color pattern 29,
Naturally, since it is a dummy, the black matrix 28 is not opened.

In the liquid crystal display device of the second embodiment configured as described above, the non-display dummy color pattern 29 on the color filter substrate side is arranged so as to correspond to the non-display dummy pixels of the thin film transistor array substrate. By contaminants re-adhering during rubbing on the color filter substrate side can be captured in the non-display area, and at the same time, the liquid crystal cell gap of the pixel electrode portion of the non-display dummy pixel area is kept equal to the display area. In addition, the drive voltage and the load capacity of the liquid crystal become normal, so that the DC offset can be prevented from being improperly applied to the liquid crystal, and the decrease in the charge retention of the liquid crystal can be reduced.

[0030]

As described above, according to the present invention, the non-display dummy pixel pattern in which the pixel arrangement pitch is shifted in the row direction or the column direction with respect to the display pixels is arranged. The coefficient of friction in the non-display dummy pixel region with respect to the cloth can be increased. Therefore, the ionic impurities due to the foreign substance adhered to the alignment film during the rubbing can be kept outside the display pixel region, and the local decrease in the charge retention of the liquid crystal, which appears with the lapse of the driving time due to the ionic impurities, can be caused. That is, display unevenness can be realized without increasing the screen frame area. For this reason, it is possible to provide an extremely useful thin film transistor array substrate of an active matrix type liquid crystal display device which simultaneously realizes compactness, large screen, high productivity, high quality, and high yield, and has a large practical effect.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a vicinity of a picture frame of a thin film transistor array substrate of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a vicinity of a chip frame of a color filter substrate of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a schematic view of a thin film transistor array substrate of a conventional active matrix type liquid crystal display device.

FIG. 4 is a schematic view of a vicinity of a screen frame of a thin film transistor substrate of the liquid crystal display device of FIG.

[Explanation of symbols]

 Reference Signs List 5 display liquid crystal cell area 8 non-display liquid crystal cell area 11 display effective pixel 13 source signal wiring 14 gate signal wiring 19 pixel electrode 20 non-display dummy pixel

Claims (3)

[Claims] 1. A liquid crystal is filled between a pair of substrates, a plurality of gate wirings and source wirings intersecting in a matrix are arranged on a first substrate, and a plurality of gate wirings and source wirings are arranged on the first substrate. A liquid crystal display device in which display pixels each formed of a thin film transistor connected to a pixel electrode are arranged in an orthogonal array at each intersection, and a counter electrode formed of a transparent conductive thin film is disposed on a second substrate. A non-display dummy pixel pattern having a pixel arrangement pitch shifted from that of the display pixels in at least one row or one column adjacent to the display pixels on the substrate in the row direction or the column direction. . 2. The liquid crystal display device according to claim 1, wherein the color pattern pitch of the color filter on the second substrate is shifted in accordance with the non-display dummy pixels on the first substrate. 3. The liquid crystal display device according to claim 1, wherein the shift amount of the non-display dummy pixels is a half pixel pitch.