JP2002258290A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which can easily make a bright spot (defect pixel which always shows a white display) to a black spot (conversion to the pixel which always shows the black display) without establishing a repair circuit, etc., and prevent the effect of the black spot processing from disappearing time-dependently. SOLUTION: A fence type salience 11 is arranged on each of a facing substrate 1 or on an array substrate 2 by resin material, etc. Especially, the thickness of a liquid crystal layer 3 in the located place of the fence type salience 11 is made to be 1/6-1/2 of the thickness of the liquid crystal layer 3 in the central of a pixel electrode 22. As the result, when the black spot processing is carried out by generating fragments 4 of the oriented films 15 and 25 using laser irradiation, it is prevented that fragments 4 of the oriented films 15 and 25 gradually are transferred to other region of the normal pixel electrode 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a normally white mode liquid crystal display device in which each pixel performs white display when no voltage is applied. In particular, it relates to a normally white mode active matrix liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices are used in various fields as display devices such as personal computers, word processors or TVs, and as projection type display devices. In particular, a thin film transistor (TF
Active matrix display devices in which switching elements such as T) are electrically connected are widely used because they can realize good display images without crosstalk between adjacent pixels.

In recent years, the use of liquid crystal display devices has been expanding and the demand for display quality has been increasing.
There is an increasing demand for reduction or prevention of bright spots that always display white. In a normally white mode liquid crystal display device, a bright spot is generated by a pixel in which a switching element does not operate. However, the bright spot is very conspicuous on a display screen of the liquid crystal display device, so that display quality is greatly impaired.

[0004] For this reason, when a bright spot is found in the inspection stage, a method of converting to a black point (dark spot) for always displaying black is used.

[0005] A black spot is typically formed by short-circuiting a pixel electrode related to a bright spot and a scanning line as follows (Japanese Patent Application No. 2000-208614).
At the time of manufacturing the array substrate, a metal float pattern for repair, which is formed simultaneously with, for example, a signal line, is provided for all the pixels, and the metal float pattern is electrically connected to the pixel electrode via a contact hole.
Then, when a bright spot is found during the lighting inspection of the liquid crystal display device, a portion where the metal float pattern and the scanning line overlap with each other is melted by laser irradiation, and the pixel electrode and the scanning line are electrically connected to each other. .

[0006] In the case of a transmission type liquid crystal display device, the use of the repair metal float pattern as described above is used.
Since the pixel electrode is made of a transparent conductive material such as ITO (Indium-Tin-Oxide), it is practically almost impossible to directly connect the pixel electrode and the scanning line by laser irradiation with a metal float pattern for repair. Because.

When a metal float pattern for repair is provided and placed, an undesirable short circuit between a pixel electrode and a scanning line may occur in a manufacturing process of an array substrate.
Undesired capacitance occurs between the scanning line and the metal float pattern.

Therefore, as a method of blackening, it has been considered to irradiate a laser beam to a pixel opening of a pixel related to a bright spot to break an alignment film in contact with a liquid crystal layer.
As a result of the destruction of the alignment film, the broken pieces of the alignment film float in the liquid crystal layer and disturb the alignment of the liquid crystal molecules. By this action, black spots that do not transmit light can be obtained. According to such a method, the above-described problem does not occur because a metal float pattern for repair is unnecessary.

[0009]

The inventors of the present invention have pursued and investigated changes over time in such a black-spotted liquid crystal display device, and have found that the effect of repair may gradually be lost. Knew. As a result of diligent studies on the cause, it was found that fragments of the alignment film generated by laser light irradiation gradually moved from inside the pixel opening related to the bright spot to another pixel opening. Thus, various studies were made on methods that can effectively prevent the movement of the fragments of the alignment film and have no adverse effects, and as a result, the present invention has been achieved.

According to the present invention, in a normally white mode liquid crystal display device, a bright spot can be easily turned to a black spot without providing a repair circuit or the like, and the effect of the black spot processing disappears with time. It is an object of the present invention to provide a liquid crystal display device capable of preventing the problem.

[0011]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a pair of insulating substrates bonded to each other via a spacer and a sealing material; and the sealing material held in a gap between the pair of insulating substrates. Liquid crystal layer sealed by the above, an alignment film provided on the surface of each of the insulating substrates so as to be in contact with the liquid crystal layer, a plurality of scanning lines arranged substantially in parallel, and substantially orthogonal to the scanning lines A plurality of signal lines arranged, pixel electrodes arranged at intersections of these scanning lines and signal lines, and from the signal lines to the pixel electrodes provided for each pixel electrode according to the applied voltage of the scanning lines A switching element for performing signal input of the liquid crystal display device, wherein one of the pair of insulating substrates is provided with a fence-shaped protrusion extending along at least both longitudinal edges of each of the pixel electrodes, Fence The thickness of the liquid crystal layer in the arrangement location of the protrusions, wherein the substantially entire of the pixel electrode is 1 / 6-1 / 2 of the thickness of the liquid crystal layer at the location to be disposed.

According to the above configuration, it is possible to easily perform blackening of a bright spot without providing a repair circuit or the like, and it is possible to prevent the effect of the blackening process from disappearing with time. In particular, even in a liquid crystal display device having a resin flattening film, it is possible to easily make a bright spot a black spot without providing a repair circuit or the like.

According to a second aspect of the present invention, in the liquid crystal display device, the hedge-shaped protrusions are provided in a lattice shape so as to surround four circumferences of each of the pixel electrodes.

With this configuration, it is possible to more reliably prevent the effect of the black spotting process from disappearing with time.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the present invention will be described with reference to FIGS.
2 will be described.

FIG. 1 is a schematic cross-sectional view schematically showing a main part of the liquid crystal display device according to the first embodiment and a state of repair. FIG. 2 is a plan view schematically illustrating a configuration of a pixel portion on a counter substrate of the liquid crystal display device according to the first embodiment.

In the display panel 10 (liquid crystal cell) of the liquid crystal display device, the array substrate 2 (TFT substrate) and the opposing substrate 1 are kept at a predetermined distance by a spacer, and the liquid crystal layer 3 is held between them. Sealing materials are arranged around the liquid crystal layer 3 to seal the liquid crystal layer 3 and join the array substrate 2 and the counter substrate 1 together.

The liquid crystal layer 3 is made of, for example, a twisted nematic (TN) type liquid crystal material. The outermost layers of the array substrate 2 and the counter substrate 1 which are in contact with the liquid crystal layer 3 have alignment films 25 and 15 made of polyimide resin or the like. Each is arranged.

In the array substrate 2, a glass substrate 26
Above, the signal lines 21 and the scanning lines are arranged in a matrix, and a TFT is arranged at each intersection of the signal lines 21 and the scanning lines. Each of the grid-shaped regions surrounded by the signal lines 21, the scanning lines, and the TFTs forms a pixel opening 5, and a pixel electrode 22 made of a transparent conductive material such as ITO is arranged so as to cover each pixel opening 5. You. Array substrate 2
Can be manufactured by the method described in Japanese Patent Application No. 11-68034, for example.

In the liquid crystal display device of the first embodiment, grid-like fence-like projections 11 are provided on the opposite substrate 1 so as to surround the four circumferences of each pixel electrode 22 by a single resin material pattern. Hereinafter, the configuration of the counter substrate 1 according to the first embodiment will be described in detail.

In the counter substrate 1, on the glass substrate 16, the pattern of the light shielding layer 12 and the red (R), green (G) and blue (B) color filter layers 18-R, 18- A color filter 13 in which G and 18-B are arranged, and a counter electrode 14 that covers the whole of these are provided. The counter electrode 14 is made of a transparent conductive material such as ITO like the pixel electrode 22. Further, the light shielding layer 12
Are arranged in a matrix in the illustrated example,
The TFTs are arranged so as to shield the locations of the TFTs on the array substrate 2 and to reliably shield the gaps between the signal lines 21 and the scanning lines and the edges of the pixel electrodes 22. That is,
The light-shielding layer 12 is arranged in a region that covers the TFT, the signal lines 21 and the scanning lines, and also covers four edges of the pixel electrode 22.

In the counter substrate 1 of the first embodiment, fence-like projections 11 made of a resin material and having predetermined protrusion dimensions are provided so as to partition the regions of the pixel openings 5 from each other. In other words, the hedge-shaped protrusions 11 having uniform protrusion dimensions are provided at positions corresponding to the matrix formed by the scanning lines and the signal lines 21 on the array substrate 2.
Is arranged.

Therefore, the location of the hedge-shaped protrusion 11 is smaller than the thickness of the liquid crystal layer at the pixel opening 5, that is, the gap G (cell gap) between the opposing substrate 1 and the array substrate 2 at the pixel opening 5. The distance between the substrate 1 and the array substrate 2 is equal to the protrusion dimension D1 of the fence-like protrusion 11,
The total protruding dimension D = D1 + D2, which is the sum of the protruding dimension D2 of the array substrate 2 due to the thickness of the signal line 11 and the scanning line, is smaller.

The total protrusion dimension D is 1/6 to 1/2 (17 to 50%) of the cell gap G, preferably 1/6.
It is set to 〜 (17 to 25%). When the total protrusion dimension D is too small, the fragments 4 of the alignment film 25 gradually move from the region of the pixel electrode 22 related to the bright spot to the region of the pixel electrode 22 related to the normal pixel adjacent thereto. The effect of preventing is not enough. On the other hand, when the protrusion dimension D is too large, it is difficult to inject the liquid crystal material when the liquid crystal material is arranged in the cell gap by injection.

If the protrusion dimension D1 of the hedge-like projection 11 is too large, rubbing is not sufficiently performed near the root of the hedge-like protrusion 11 in the rubbing step for forming the alignment of the alignment film 25, and However, there is a problem that the region is not formed or a region deviated from a predetermined orientation is generated.
Therefore, when the liquid crystal material is dropped on one of the substrates before the opposing substrate 1 and the array substrate 2 are combined with each other, instead of the method of injecting the liquid crystal material from the narrow injection port, a barrier is formed. The protrusion dimension D1 of the protrusion 11 cannot be made too large.

Therefore, the protrusion dimension D of the fence-like projection 11
1 is set to 4/10 (25%) or less, preferably 15% or less of the cell gap G. Here, the protrusion dimension D2 due to the thickness of the signal line 11 or the like is 1/10 of the cell gap G.
(10%) or less, the total protrusion dimension D is in the above range.

Some examples of specific numerical values of the total protrusion dimension D are 0.9 μm, 1.0 μm and 1.5 μm when the cell gap G is 5 μm. At this time, the ratio to the cell gap G is 1
8%, 20% and 30%. From the viewpoint of sufficiently avoiding the occurrence of rubbing defects, the total protrusion dimension D is set to about 0.8
It is particularly preferred that the thickness be 1.0 to 1.0 μm.

Resin layer 1 for forming fence-like projections 11
The pattern 7 can be provided in the same manner as the pattern of the photoresist. That is, a photoresist resin solution is applied on a substrate, and then exposed and developed using a photomask. For example, it can be provided by a resist material made of an acrylic resin.

Resin layer 1 for forming fence-like projections 11
The pattern 7 can be provided at the same time as the spacer projection for keeping the cell gap constant by using a halftone exposure technique or a similar technique. For example, using a negative resist, strong exposure is performed by diffractive light from the back surface using the pattern of the light-shielding layer 12 as a mask, and weak exposure is performed from the front side by a photomask that shields only the spacer protrusion formation portion. As a result, the hedge-shaped protrusion 11 having a smaller protrusion size than the spacer protrusion is provided to overlap the pattern of the light shielding layer 12 with a width smaller than that of the pattern of the light shielding layer 12.

When the light-shielding layer 12 on the counter substrate 1 is not a metal film but a resin film having a large thickness, the light-shielding layer 12 contributes to the projection size of the fence-like projections 11.

When assembling the display panel 10 (liquid crystal cell) from the counter substrate 1 and the array substrate 2 as described above,
For example, the following is performed. First, a polyimide resin film is formed on the pattern formation surfaces of both substrates 1 and 2, and liquid crystal alignment films 15 and 25 are formed by rubbing. Next, by applying a sealing material along the edge on the counter substrate 1,
A pattern of a sealing material surrounding the entire display pixel area except for the liquid crystal injection port is created. When bonding the opposing substrate 1 and the array substrate 2 via a sealing material,
The rubbing angles of the upper alignment films 15 and 25 cross each other at 90 degrees. Thereafter, the liquid crystal material is vacuum-injected, and then the injection port is sealed with a sealing material. Finally, a portion corresponding to the front and back surfaces of the display panel 10, that is, the counter substrate 1
And a polarizing plate are attached to the outer surface of the array substrate 2 and the outer surface of the array substrate 2, respectively. At this time, the absorption axis of the polarizing plate is
In addition, in each of the substrates 1 and 2, the absorption axis of the polarizing plate and the rubbing direction of the alignment films 15 and 25 are parallel to each other.

After the display panel 10 was completed, a lighting inspection was performed, and a laser irradiation was performed to break the alignment film 15 or 25 to disturb the alignment of the liquid crystal at the location of the pixel of the detected bright spot. As a result, the light transmission could be almost completely changed to a black spot by an appropriate laser irradiation operation. In addition, the effect of black spotting was maintained even after a long-time continuous driving test.

Next, a second embodiment will be described with reference to FIG. FIG. 3 is a schematic laminated cross-sectional view of the counter substrate according to the second embodiment.

In the second embodiment, the fence-like projections 11
Resin light-shielding layer 12 and two color filter layers 1
8 are provided by being superimposed. More specifically, a case where a red color filter layer 18-R corresponding to a pixel displaying red (R) and a green color filter layer 18-R corresponding to a pixel displaying green (G) are arranged adjacent to each other. The edge of the red color filter layer 18-R and the edge of the green color filter layer 18-G are overlapped with each other on the light-shielding film 12 made of resin, so that the red display pixel and the green display pixel Is formed. Similarly, the edge of the green color filter layer 18-G and the edge of the blue color filter layer 18-B are
2 to form a fence-like projection 11 that separates between the green display pixel and the blue display pixel, and the edge of the blue color filter layer 18-B and the red color filter layer 1 are formed.
Hedge-shaped protrusion 11 that overlaps the edge of 8-G on light-shielding film 12 to partition between a green display pixel and a blue display pixel
Is formed.

Therefore, the projection height D of the fence-like projections 11
When the thickness of the color filter layer 18 of each color is equal, the color filter layer 1
8 is twice the thickness D4.

In manufacturing the counter substrate 1 of the second embodiment,
After forming a pattern of a resin light-shielding film 12 on a glass substrate 16, a resist material resin containing a blue pigment or dye, a resist material resin containing a green pigment or dye, and a resist material containing a red pigment or dye With respect to the resin, application by a spin coater and patterning by photolithography are sequentially performed.

At the time of this patterning, for example, the pattern of the filter layers 18-R, -G, and -B of each color is formed in a stripe shape for each column of the pixel electrodes 22 along the signal line 21. Hedge-shaped protrusion 11 only at the location corresponding to
Is provided. In the case of such a stripe shape, the fence-like projection 11 is not provided at the scanning line. However, since the pixel opening is usually formed in an elongated shape along the signal line 21, the scanning line is formed. The probability that the fragments 4 of the alignment film will escape from the side of is small. Therefore, even when the hedge-shaped protrusions 11 are provided along both edges in the longitudinal direction of the pixel electrode 22 as described above, the same effect as the case where the hedge-shaped protrusions 11 are provided so as to surround the four circumferences of each pixel electrode 22 is obtained. Can be obtained.

Note that the filter layers 18-R, -G,
When the pattern of -B is provided, the arrangement is such that the red, green, and blue regions are not in a stripe shape, but are staggered with each other;
That is, when the region of each color is always arranged so as to be surrounded by the region of another color, the fence-like projection 11 can be provided so as to surround the four circumferences of the pixel electrode 22.

Even when the pattern of the light-shielding layer 13 is a thin film made of a metal layer, a sufficient projection height can be obtained by stacking a plurality of resin-made filter layers 18 having a sufficient thickness. It is also possible to provide a fence-like projection 11 having a thickness. In some cases, filter layers 1 of three colors
Hedge-shaped protrusions 11 can also be provided by superimposing 8-R, -G, and -B.

With the configuration of the above embodiment, it is possible to easily make a bright spot a black spot without providing a repair circuit or the like, and to prevent the effect of the black spot processing from disappearing with time. it can.

In particular, in the case of a liquid crystal display device of a type in which the pattern of the signal lines and scanning lines on the array substrate is covered with a resin flattening film of 1 μm or more to improve the pixel aperture ratio, ie, the thickness of the signal lines and the like In some cases, when projections are not formed on the surface of the array substrate, movement of fragments of the alignment film is not hindered at all without providing hedge-shaped projections with a resin layer or the like. Therefore, the effect of the embodiment is particularly prominent in a liquid crystal display device having a resin flattening film.

In the above embodiment, the fence-like projections 11 are described as being provided on the opposing substrate 1. However, they may be provided on the array substrate 2, and in some cases, the two substrates 1 and 2 may be provided.
It can also be provided on top.

In the above embodiment, the liquid crystal display device has been described as being of the light transmission type, but the same applies to the case of the light reflection type. This is because the repair by the laser beam can be performed by focusing on the alignment film 15 from the counter substrate 1 side. In the case of a light-reflection type liquid crystal display device, the pixel electrode is necessarily a grid-shaped region formed by the signal line and the scanning line, and in the above embodiment, the switching element arranged for each pixel electrode is a TFT. As explained,
Thin film diode (TFD) or MIM (metal-insu)
(lator-metal) element.

[0044]

In a normally white mode liquid crystal display device, a bright spot can be easily turned into a black spot without providing a repair circuit or the like, and the effect of the black spot processing is prevented from disappearing with time. can do. In particular, even in a liquid crystal display device having a resin flattening film, it is possible to easily make a bright spot a black spot without providing a repair circuit or the like.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a main part of a liquid crystal display device according to a first embodiment and a state of repair.

FIG. 2 is a schematic plan view illustrating a counter substrate of the liquid crystal display device according to the first embodiment.

FIG. 3 is a schematic cross-sectional view of a counter substrate of a liquid crystal display device according to a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 counter substrate 11 hedge-like projection 12 light shielding layer 13 color filter layer 14 counter electrode 15 alignment film on counter substrate 2 array substrate 21 signal line 22 pixel electrode 25 alignment film on array substrate 3 liquid crystal layer 4 fragment of alignment film 5 pixel Opening

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H089 LA10 NA25 QA16 RA05 TA01 TA04 TA09 TA12 TA13 TA15 2H090 HB08Y JB02 KA05 LA09 LA15 MA06 MB01 2H091 FA02Y FA08X FA08Z FA35Y GA01 GA06 GA13 HA07 LA16 2H092 GA29 JA03 JA24 MA46 PA02 PA08 PA09 PA11 QA07

Claims (4)

[Claims] A pair of insulating substrates bonded to each other via a spacer and a sealing material; a liquid crystal layer held in a gap between the pair of insulating substrates and sealed by the sealing material; An alignment film provided on the surface of the liquid crystal layer so as to be in contact with the liquid crystal layer; a plurality of scanning lines arranged substantially in parallel; a plurality of signal lines arranged substantially orthogonal to the scanning lines; A liquid crystal display comprising: a pixel electrode disposed at each intersection of signal lines; and a switching element provided for each pixel electrode to input a signal from the signal line to the pixel electrode in accordance with a voltage applied to the scanning line. In the device, any one of the pair of insulating substrates is provided with a fence-like protrusion extending along at least both longitudinal edges of each of the pixel electrodes, and a thickness of the liquid crystal layer at a location where the fence-like protrusion is arranged. The liquid crystal display device, wherein the substantially entire of the pixel electrode is 1 / 6-1 / 2 of the thickness of the liquid crystal layer at the location to be disposed. 2. The liquid crystal display device according to claim 1, wherein said hedge-shaped projections are provided in a grid shape so as to surround four circumferences of each of said pixel electrodes. 3. The liquid crystal display device according to claim 1, wherein said hedge-like projections are formed by patterning one resin material layer. 4. The hedge-shaped protrusion is formed by laminating a light-shielding layer made of a resin material and at least one color filter layer made of a resin material, or a plurality of color filter layers made of a resin material. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed by overlapping.