JP3912850B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND 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 that drives a liquid crystal using a non-linear element and has a feature in the structure of the thin film transistor array substrate.
[0002]
[Prior art]
In recent years, based on advances such as microfabrication technology, material technology, and high-density packaging technology, and the rapid spread of multimedia equipment, in a wide range of screen sizes, and in various applications such as AV, OA, in-vehicle, information communication, The proportion of liquid crystal display devices is rapidly expanding. The liquid crystal display device has attracted the attention of the entire electronics industry as a key device replacing the CRT. Under such circumstances, the thin and lightweight advantages unique to liquid crystal display devices have been further evolved, and product areas that have been difficult to achieve with CRTs (for example, A4 and B5 size notebook computers to sub-notebook computers, DIN standard cars) Navigation systems, monitor-integrated video movies, pen-input personal digital assistants, etc.)
[0003]
In the field of liquid crystal display devices, in particular, the development of technology for how large screens can be obtained relative to the size of the device, in other words, the development of narrow frame technology that reduces the peripheral area that does not contribute to display. , Has become an urgent need.
[0004]
First, an outline of a thin film transistor array substrate of a conventional active matrix 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, 2 is an effective area of a thin film transistor array substrate necessary as a liquid crystal display device, and here shows a case of multiple chamfering in which effective areas for two panels are arranged. Reference numerals 3a and 3b denote unit effective areas for one panel, which are called chips. Reference numeral 4 denotes an area necessary for conveyance or formation of a recognition pattern in the manufacturing process of the mother glass substrate 1 and is called a mother glass frame.
[0005]
A display liquid crystal cell region 5 in which thin film transistors serving as active elements for switching liquid crystals are arranged in a matrix is disposed in the central portion inside the effective region 2 of the thin film transistor array substrate. Around the display liquid crystal cell region 5, a drive driver mounting region 6, a seal region 7 for attaching and fixing a counter substrate to enclose and fix the liquid crystal material in the display liquid crystal cell region 5, and the display liquid crystal cell region 5 A non-display liquid crystal cell region 8 sandwiched between the seal region 7 is provided. The non-display liquid crystal cell region 8 has a marginal region that exists in order to prevent the seal region 7 from overlapping the display screen region 5 and causing a display defect even if the position of the seal region 7 is displaced due to manufacturing variations. It is. Reference numeral 9 denotes a region where the seal region 7 and the non-display liquid crystal cell region 5 are combined, and is referred to as a screen frame here. Reference numeral 10 denotes a region where the display liquid crystal cell region 5 and the non-display liquid crystal cell region 8 are combined, and is referred to herein as a liquid crystal cell region.
[0006]
In order to use the mother glass 1 as effectively as possible, first, there is a method of minimizing the size of the mother glass frame 4. However, since this is restricted by the structure of the manufacturing equipment, a size below a certain level cannot be expected at present. Further, since the size of the mother glass frame 4 takes a constant value regardless of the number of chamfers of the chips 3a and 3b, the influence per chip is dispersed as the number of chamfers increases, and the influence on the chip size is so large. Absent.
[0007]
Secondly, if the effective area 2 of the thin film transistor array substrate is considered to be constant, the maximum chip size in each chamfering number is determined automatically. Therefore, in order to enlarge the display liquid crystal cell area 5, the screen frame 9 is reduced. There is no way to do it. Further, even when the size of the display liquid crystal cell region 5 is fixed and the number of multi-cavities is maximized, it is effective to minimize the size of the chips 3a and 3b by reducing 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 effect thereof becomes greater as the number of chamfers increases.
[0008]
For this reason, usually, design measures are taken to minimize the screen frame 9. FIG. 4 shows the details of the vicinity of the screen frame 9 in FIG. 3 in detail. Here, reference numeral 11 denotes display effective pixels in the display liquid crystal cell region 5, which are arranged orthogonally. A non-display dummy pixel 12 in the non-display liquid crystal cell region 8 is orthogonally arranged so as to extend the display effective pixel 11. 13 is a source signal wiring, and 14 is a gate signal wiring. Here, similarly to the display effective pixel 11, the source signal wiring 13 and the gate signal wiring 14 are connected to the non-display dummy pixel 12, and the same driving as the display effective pixel 11 is performed. That is, in many cases, the non-display dummy pixels 12 are usually arranged in one or more rows by repeating exactly the same pixel pattern as the display effective pixels 11 as they are. There are several reasons for disposing the non-display dummy pixels 12 in this way, but the biggest reason is that there is a problem in reliability of display quality.
[0009]
The issues regarding the reliability of display quality are as follows.
Usually, the alignment process performed to align liquid crystal molecules in a predetermined direction is performed using a cloth made of fibers such as rayon and nylon, and the alignment film (polyimide resin) on the substrate is fixed in a certain direction under a certain load. The rubbing method is used. However, at that time, the alignment film scraped off from the substrate by friction and adhered to the cloth is reattached to the substrate as a foreign substance, and the amount of adhesion increases as the change in the step shape of the substrate increases. Tend. In other words, it reattaches in a concentrated manner at the boundary between the area where the pixels are arranged and the wiring area. The alignment film foreign matter reattached has broken imide bonds due to frictional heat during rubbing and moisture in the air, so that the carboxylic acid is easily separated as ions. These diffuse as ionic impurities into the liquid crystal over time. This ionic impurity deteriorates the voltage holding ratio of the liquid crystal, but in a state where it is uniformly diffused in the liquid crystal, it is not recognized as luminance unevenness on the image display and does not cause a big problem.
[0010]
However, as described above, the distribution of the reattached foreign matter is concentrated around the screen from the beginning, and uniform diffusion is impossible. Furthermore, since these impurities are ionic, they have the property of moving in the liquid crystal cell as the drive time elapses, and are particularly greatly affected by the gate signal having a large DC component. That is, ionic impurities move in a certain direction depending on the scanning direction of the gate, and a region where the ions exist in a concentrated manner is formed. Due to the ionic impurities concentrated in this region, the local charge retention rate is lowered and observed as luminance unevenness on the image display.
[0011]
Therefore, in order to prevent luminance unevenness, which is a problem in reliability of display quality, the non-display dummy pixels 12 that are normally driven are arranged in the non-display liquid crystal cell region 8, thereby generating ionic impurity sources. The reattachment area of the rubbing foreign material is moved 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 gate electrode of the non-display dummy pixel 12 in the non-display liquid crystal cell area 8. Staying in the vicinity is an effective means.
[0012]
[Problems to be solved by the invention]
However, in the above-described conventional structure, the seal region 7 is reduced when trying to reduce the area of the chips 3a and 3b under the same screen size, or to minimize the size of the screen frame 9 for increasing the number of multiple faces. Is not less than a certain width from the viewpoint of reliability. Therefore, one method is to cut off the non-display liquid crystal cell region 8 and reduce it. In order to reduce the non-display liquid crystal cell region 8, in the conventional technique, the number of arrangement columns of the non-display dummy pixels 12 is cut off, and only a minimum of one row or one column can be arranged in many cases.
[0013]
This is because when the non-display liquid crystal cell region 8 is reduced without reducing the number of rows or columns of the non-display dummy pixels 12, the worst case is a seal in the case where the dimensional variation in manufacturing of the seal region 7 is taken into consideration. Since the region 7 overlaps with the non-display dummy pixel 12 and the overlapped portion cannot have liquid crystal itself, the function as a trapping electrode for the ionic impurities of the non-display dummy pixel 12 described in the prior art is provided. This is because loss of luminance on the image display cannot be prevented. Furthermore, the contact surface with the active substrate side in the seal region 7 is usually the source signal wiring 13 or the gate signal wiring 14 which is substantially uniform with the non-display dummy pixel 12 having a partially different step and surface state. This is because the contact causes a risk of causing a problem of a sealing property due to a decrease in adhesion and a problem of a gap unevenness of a liquid crystal cell due to unevenness in level difference.
[0014]
However, even if the minimum number of non-display dummy pixels 12 in one row or column can be arranged, if the non-display dummy pixels 12 are orthogonally arranged in the extended portion of the display effective pixels 11, the source signal wiring 13 and Since the arrangement with the gate signal wiring 14 is substantially linear, the unevenness of the substrate becomes monotonous. That is, the coefficient of friction becomes small, and the contaminants adhering to the rubbing cloth cannot be completely captured in the region of the non-display dummy pixels 12, and the remaining contaminants adhere to the display effective pixel 11 region. is there.
[0015]
In order to solve the above-described 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]
[Means for Solving the Problems]
In order to solve the above problems, a liquid crystal display device according to the present invention is a non-display dummy pixel pattern in which a pixel arrangement pitch is shifted in the row direction or the column direction with respect to the display pixels adjacent to the orthogonally arranged display pixels. Are arranged in at least one row or one column , and the gate wiring or the source wiring is bent corresponding to the shift of the pixel arrangement pitch in the non-display dummy pixel pattern portion .
[0017]
According to this, 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 , and the gate is arranged corresponding to the shift of the pixel arrangement pitch in the non-display dummy pixel pattern portion. Since the wiring or the source wiring is bent , the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth can be increased. 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 has the same effect as a conventional non-display dummy pixel for several rows or columns in a narrow area Can be placed. Therefore, even if there is redeposition contamination from the rubbing cloth, they can be kept in the non-display liquid crystal cell region, and thus uniform and good image display characteristics can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, liquid crystal is filled between a pair of substrates, and a plurality of gate wirings and source wirings intersecting in a matrix are disposed on the first substrate, and the gate wirings and In a liquid crystal display device in which display pixels made of thin film transistors connected to pixel electrodes are arranged in an orthogonal arrangement at each intersection with a source wiring, and a counter electrode made of a transparent conductive thin film is placed on a second substrate The non-display dummy pixel pattern in which the pixel arrangement pitch is shifted with respect to the display pixels is arranged at least in one row or one column adjacent to the display pixels on the first substrate in the row direction or the column direction.
[0019]
This has the effect of increasing the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth.
[0020]
According to the second aspect of the present invention, the color pattern pitches of the color filters of the second substrate are 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 of the non-display dummy pixel region on the color filter side with respect to the rubbing cloth.
[0021]
The invention according to claim 3 is such that the shift amount of the non-display dummy pixels is a half pixel pitch.
According to this, similarly, the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth is increased.
[0022]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.
(Embodiment 1)
FIG. 1 is a schematic view of the vicinity of a screen 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.
[0023]
In FIG. 1, 5 is a display liquid crystal cell region, and 11 is a display effective pixel. This 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 TFT semiconductor layer 17, the drain electrode 18, and the drain electrode 18. And the pixel electrode 19.
[0024]
Reference numeral 8 denotes a non-display liquid crystal cell region, in which a non-display dummy pixel 20 is formed. The non-display dummy pixel 20 is connected to the source signal wiring 13 and the gate signal wiring 14 in the same manner as the display effective pixel 11, and includes a dummy source electrode 21, a dummy gate electrode 22, a dummy semiconductor layer 23, and a dummy drain electrode. 24 and a dummy pixel electrode 25. Further, the non-display dummy pixels 20 are arranged so as to be shifted from the display effective pixels 11 by a half pixel pitch in the row direction. That is, in the non-display dummy pixel 20 portion, 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, the size of the TFT, the capacitance, etc. are set to the dummy source electrode 21 or the dummy gate. The design parameters of the electrode 22, the dummy semiconductor layer 23, the dummy drain electrode 24, and the dummy pixel electrode 25 are optimized and adjusted.
[0025]
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 non-display dummy pixels 20 is limited, the non-display dummy pixel 20 portion The source signal wiring 13 connected to the dummy source electrode 21 is bent, and the coefficient of friction changes abruptly in this portion. Therefore, the contaminants reattached from the rubbing cloth are in this portion, that is, the region of the display effective pixel 11. Will be captured outside. Therefore, the minimum dummy area is sufficient, and when the non-display dummy pixel is not arranged without reducing the distance between the seal area 7 and the non-display dummy pixel 20, or when the non-display dummy pixel of the orthogonal arrangement is arranged. It is possible to prevent defects in display characteristics that occur.
[0026]
In the above description, the example in which the arrangement of the non-display dummy pixels 20 is shifted in the row direction, that is, the direction in which the number of gates is increased is described. Further, the number of arrangement lines and the shift amount may be freely selected as necessary.
[0027]
(Embodiment 2)
FIG. 2 is a schematic view of the vicinity of the screen frame of the color filter substrate in the liquid crystal display device according to Embodiment 2 of the present invention. In this embodiment, a case where the non-display dummy pixels on the thin film transistor array substrate side are arranged in two columns with a half-pixel pitch shift will be described.
[0028]
In FIG. 2, reference numeral 27 denotes a display color pattern, in which RGB are arranged in a stripe shape, and a black matrix 28 is opened correspondingly. Reference numeral 29 denotes a non-display dummy color pattern, which is arranged with a half-pixel pitch shift for each row, and RGB is arranged in a delta shape. Since the non-display dummy color pattern 29 is a dummy, naturally, the black matrix 28 is not opened.
[0029]
In the liquid crystal display device according to the second embodiment configured as described above, the non-display dummy color pattern 29 on the color filter substrate side is arranged in a form corresponding to the non-display dummy pixels of the thin film transistor array substrate. Contaminants that re-adhere during rubbing on the 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 that of the display area. The driving voltage and the load capacity become regular, and it is possible to prevent the DC offset from being irregularly applied to the liquid crystal, and to reduce the decrease in the charge retention rate of the liquid crystal.
[0030]
【The invention's effect】
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 pixel is arranged , and the pixel arrangement pitch shift in the non-display dummy pixel pattern portion. Since the gate wiring or the source wiring is bent correspondingly, the friction coefficient of the non-display dummy pixel region with respect to the rubbing cloth can be increased during the rubbing alignment process. Therefore, ionic impurities caused by the reattached alignment film foreign matter during rubbing can be kept outside the display pixel region, and the local liquid crystal charge retention rate that appears with the lapse of driving time due to the ionic impurities is reduced. That is, display unevenness can be realized without increasing the screen frame area. For this reason, it is possible to provide a thin film transistor array substrate for an active matrix type liquid crystal display device that can achieve compactness, large screen, high productivity, high quality, and high yield at the same time, and its practical effect is great.
[Brief description of the drawings]
FIG. 1 is a schematic view of the vicinity of a screen 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 view of the 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.
4 is a schematic view of the vicinity of a screen frame of a thin film transistor substrate of the liquid crystal display device of FIG. 3;
[Explanation of symbols]
5 Display liquid crystal cell region 8 Non-display liquid crystal cell region 11 Display effective pixel 13 Source signal wiring 14 Gate signal wiring 19 Pixel electrode 20 Non-display dummy pixel

Claims (3)

A liquid crystal is filled between a pair of substrates, and on the first substrate, a plurality of gate wirings and source wirings crossed in a matrix are disposed, and at each intersection of the gate wiring and the source wiring, In a liquid crystal display device in which display pixels composed of thin film transistors connected to pixel electrodes are arranged in an orthogonal arrangement and a counter electrode composed of a transparent conductive thin film is disposed on a second substrate, the display on the first substrate A non-display dummy pixel pattern in which at least one row or one column of non-display dummy pixel patterns is arranged adjacent to the pixels in the row direction or the column direction and the pixel arrangement pitch is shifted in the row direction or the column direction with respect to the display pixels. A liquid crystal display device, wherein the gate wiring or the source wiring is bent in accordance with a shift in pixel arrangement pitch in the portion .   2. The liquid crystal display device according to claim 1, wherein the color pattern pitch of the color filter of the second substrate is shifted in accordance with the non-display dummy pixels of 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.

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