JP2002006328A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active matrix type liquid crystal display device in which leaked light in the gap in the edge of the display region is made hardly visible and excellent screen quality is obtained. SOLUTION: A light-shielding electrode 115 is formed to cover the periphery of the display region 103a. A voltage to always generate black display during an image is displayed is applied between the light-shielding electrode 115 and a counter electrode 203 so that the periphery of the display region 103a is always displayed black in a frame form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cell structure of a liquid crystal display device, and more particularly to a technique for preventing light leakage in an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used in personal computers,
It is used in various fields as a flat display device such as a word processor or a TV, and as a projection flat display device. Among them, an AM (active matrix) liquid crystal display device in which a switching element is electrically connected to each pixel electrode can achieve a good display image without crosstalk between adjacent pixels. Is being done.

A conventional general AM type liquid crystal display device has a thin film transistor (hereinafter, referred to as T) functioning as a switching element.
FT), an array substrate on which pixel electrodes, signal line electrodes, and scanning line electrodes connected to the array substrate are formed, and a counter substrate on which a counter electrode facing the pixel electrodes and a color filter of three primary colors (RGB) are formed are arranged to face each other. At the same time, silver paste etc. is placed around the screen as an electrode transfer material (transfer material) that applies voltage from the array substrate to the opposing substrate,
The liquid crystal composition is sandwiched between the two substrates. Further, a polarizing plate is arranged on both sides of the two substrates, and a color image is displayed by operating as an optical shutter for modulating the light of the backlight.

[0004]

By the way, the array substrate and the counter substrate differ in the expansion amount of the substrate due to the difference in the thermal history in the manufacturing process. For this reason, when two substrates are bonded to each other, a gap is generated between the display area end of the array substrate and the display area end of the opposing substrate due to a difference in the amount of expansion between the substrates, and light from the backlight leaks therefrom. The display quality may be significantly reduced.

On the other hand, in a liquid crystal display device used for a notebook type personal computer or the like, a CP with a high performance of the personal computer is used.
There is a demand for an increase in the power consumption of the U and an increase in the usage time in battery driving, and further lower power consumption is required. In general, in a liquid crystal display device, the power consumption of the backlight is large. Therefore, it is considered that increasing the aperture ratio per pixel and lowering the driving voltage of the backlight is effective for reducing the power consumption.

Conventionally, as a structure for increasing the aperture ratio,
While forming an insulating film on the electrode wiring of the array substrate,
On top of that, there is a structure in which pixel electrodes are formed so as to extend outward until they overlap with the electrode wiring of the array substrate (hereinafter referred to as a pixel-placed structure). In this pixel-placed structure, the electrode wiring of the array substrate performs light-shielding between pixels or outside the pixels, that is, a black matrix function. As a result, in the liquid crystal display device having the pixel-placed structure, not only the aperture ratio can be increased, but also the black matrix formed on the counter substrate can be eliminated. However, light shielding outside the display area, that is, outside the outermost pixel cannot be shielded by the wiring electrode alone. Therefore, it is necessary to provide a frame-shaped black matrix on the counter substrate side so as to cover the periphery of the display area. Becomes

In this case, in the assembling process, it is necessary to precisely match the black matrix provided on the counter substrate with the electrode wiring functioning as a black matrix on the array substrate. Therefore, the alignment accuracy in this portion is poor, and when the two overlap little, light leakage occurs at the end of the display area, causing a problem that the screen quality is remarkably deteriorated. To prevent this light leakage by using only alignment technology, a high level of alignment accuracy is required, and there are various restrictions in manufacturing, such as restrictions on the process using heat and restrictions on the material of the substrate. Will occur.

It is a first object of the present invention to provide a liquid crystal display device which makes it difficult to see light leakage occurring at the edge of a display area and has excellent screen quality.

A second object of the present invention is to provide a liquid crystal display having excellent screen quality, in which light leakage at the edge of a display area is hardly seen when the aperture ratio is increased by a pixel-mounted structure. A display device is provided.

[0010]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a first substrate having a plurality of pixel electrodes regularly arranged in a display area; In a liquid crystal display device including a second substrate on which a counter electrode opposed to a pixel electrode is formed, and a liquid crystal material sandwiched between the substrates, the liquid crystal display device covers the periphery of the display region on the first substrate. The light-shielding electrode is formed as described above, and a potential for constantly displaying black is supplied between the light-shielding electrode and the counter electrode during image display.

[0011] According to the above configuration, during the image display, the periphery of the display area is always black-displayed in a frame shape by the light-shielding electrode covering the periphery of the display area. Even if there is a gap between the edge of the area and the edge of the display area of the second substrate, light leakage occurring at the edge of the display area is suppressed, and light leakage is hardly visible to the outside.

In order to achieve the second object, a second aspect is provided.
According to the invention, a plurality of pixel electrodes are regularly arranged in a display area, and these pixel electrodes are connected via a switching element near each intersection of a plurality of scanning line electrodes and a plurality of signal line electrodes which intersect with each other. A first substrate, a second substrate on which a counter electrode facing the pixel electrode is formed, and a liquid crystal material sandwiched between these substrates. A light shielding layer made of a linear semiconductor layer is arranged outside the arranged signal line electrode so as to overlap the outer edge of the signal line electrode in a plane.

In a preferred embodiment, when there is no signal line electrode outside the pixel electrode disposed at the end of the display area and a pseudo signal line electrode is disposed at that position, the outside of the pseudo signal line electrode is provided. Then, a light-shielding layer formed in a linear shape is disposed so as to overlap the outer edge of the pseudo signal line electrode in a plane.

In a preferred embodiment, the transmittance of the light shielding layer is set to 50% or less.

According to the above configuration, even when the signal line electrode functioning as a black matrix on the first substrate and the black matrix formed on the surface of the opposing substrate have little planar overlap, the first substrate can be used. Due to the light shielding layer formed on the side, light leakage occurring at the end of the display area is suppressed, and the light leakage is hardly seen outside.

In a preferred embodiment, a plurality of pixel electrodes are regularly arranged in a display area, and a switching element is provided near each intersection of a plurality of scanning line electrodes and a plurality of signal line electrodes where these pixel electrodes intersect with each other. First connected via
A liquid crystal display device including a substrate, a second substrate on which a counter electrode facing the pixel electrode is formed, and a liquid crystal material sandwiched between these substrates, the liquid crystal display device being disposed at the end of the display region. The width of the signal line electrode is formed wider than the width of the other signal line electrodes.

In a preferred embodiment, the width of the signal line electrode disposed at the end is several μm larger than the width of the other signal line electrodes.
m, preferably 10 μm or more.

According to the above structure, even when the signal line electrode functioning as a black matrix on the first substrate and the black matrix formed on the surface of the second substrate have a small planar overlap, the first substrate can be used. By the signal line electrode disposed at the left end (and right end), light leakage occurring at the end of the display area is suppressed, and light leakage is hardly seen to the outside.

[0019]

Next, an embodiment in which the liquid crystal display device according to the present invention is applied to an AM type liquid crystal display device will be described.

[Embodiment 1] In Embodiment 1, a countermeasure for light leakage of a liquid crystal display device in which color filters are arranged on the array substrate side will be described.

FIG. 1 is an overall configuration diagram of the liquid crystal display device according to the first embodiment, and FIG. 2 is a partial sectional view thereof. Hereinafter, description will be made with reference to FIGS.

The liquid crystal display device 10 includes an array substrate 100,
A counter substrate 200 and a liquid crystal layer 400 sandwiched between these substrates are provided.

The array substrate 100 is a transparent glass substrate 10
1, the surface of which is divided into a display area 103a and a non-display area 103b. The display area 103a includes the signal line electrode 104 and the scanning line electrode 10 in the display area 103a.
5, a TFT 106 and a pixel electrode 107 are formed.

The signal line electrode 104 and the scanning line electrode 105 intersecting with the signal line electrode 104 are arranged in a matrix, and a TFT 106 as a switching element is arranged at the intersection of the two electrodes. The signal line electrode 104 and the scanning line electrode 105 are electrically insulated by an insulating film (not shown).
The gate electrode of the TFT 106 is connected to the scanning line electrode 105. Further, a source electrode (or a drain electrode) is connected to the signal line electrode 104, and a drain electrode (or the source electrode) is connected to the pixel electrode 107.

On the display area 103a of the array substrate 100, R, G, and B color filters 110 made of, for example, an organic resin are formed according to a predetermined arrangement pattern. When the color filter 110 is formed, a step of separately applying a resist or the like can be omitted by using a photosensitive resin.

The pixel electrode 107 is formed on the color filter 110, and is electrically connected to the drain electrode (or source electrode) of the TFT 106 through a contact hole formed at a predetermined position.

In the non-display area 103b of the array substrate 100, a drive circuit 108 composed of a TFT and an external terminal 109 connected to the drive circuit 108 for supplying electric power and various signals from outside are formed. ing.

As a characteristic configuration of the first embodiment, a light-shielding electrode 115 is formed in a frame shape so as to cover the periphery of the display area 103a. The light-shielding electrode 115 is formed in the same step as the pixel electrode 107, and the drive circuit 1
08 or an external circuit. And
During image display, the light-shielding electrode 115 and the later-described counter electrode 20
3 is supplied with a potential for black display at all times. Since the light-shielding electrode 115 and the pixel electrode 107 are electrically insulated, the light-shielding electrode 115 is
Does not participate in the display.

On the other hand, the opposite substrate 200 is the array substrate 10
It is composed of a transparent glass substrate 201 like 0,
On its surface, a frame 202 for shielding light around the display area
Is formed of an insulating organic film or a laminated structure of a chromium oxide film and a chromium film. Further, the counter substrate 2
00, at least the display area 103a
Is formed in a size to cover the counter electrode 203.

The array substrate 100 and the counter substrate 20
0 are opposed to each other with a predetermined gap,
are bonded together by a seal material 300 applied on the non-display area 103b so as to surround a. This sealing material 3
An injection port 301 for injecting a liquid crystal material is formed in a part of the liquid crystal layer 00, and the liquid crystal layer 400 is filled through the injection port 301 after bonding. 1 and 2
, The illustration of the polarizing plate and other members is omitted.

The liquid crystal display device 10 constructed as described above
According to the above, during image display, the light-shielding electrode 115 and the counter electrode 2
03, the potential for black display is always supplied.
The periphery of the display area 103a is always displayed in a black frame. Accordingly, even if a gap is generated between the display area end of the array substrate 100 and the display area end of the counter substrate 200 due to a difference in the amount of expansion between the substrates when the two substrates are bonded together, Light leakage occurring at the end is suppressed, and light leakage becomes difficult to see outside. Therefore,
Without causing significant deterioration of screen quality due to light leakage,
A liquid crystal display device with excellent screen quality can be realized.

The width of the light-shielding electrode 115 needs to be large enough to allow a gap between a display area end of the array substrate 100 and a display area end of the counter substrate 200 which can be expected when two substrates are assembled. It is. Specifically, about 10 μm is sufficient.

The light-shielding electrode 115 may have a shape other than a frame shape. For example, two L-shaped or U-shaped electrode patterns may be combined.

[Second Embodiment] In a second embodiment, a countermeasure against light leakage in a liquid crystal display device having a pixel-top structure will be described.

FIG. 3 is a configuration diagram of the liquid crystal display device according to the second embodiment. FIG. 3A is a schematic plan view, and FIG.
Shows partial sectional views of the display area end A. In FIG. 3, the same reference numerals are given to the same parts as those in FIGS. In addition, illustration and description of the parts already described in the first embodiment will be appropriately omitted.

The basic structure of the liquid crystal display device 20 is almost the same as that of the first embodiment, and the array substrate 100 and the opposing substrate 2
00 and a liquid crystal layer 400 sandwiched between these substrates.

The array substrate 100 is a transparent glass substrate 10
The light-shielding layer 117 formed of a semiconductor layer is formed on the surface of the light-shielding layer 117 as a characteristic feature of the second embodiment. On the light shielding layer 117, an interlayer insulating film 1 is formed.
18, and a signal line electrode 104 is further formed thereon. The signal line electrode 104 shown in FIG. 3B is the signal line electrode disposed at the leftmost end of the screen,
Reference numeral 7 is linearly patterned along the signal line electrode 104 so as to overlap the side edge of the signal line electrode 104 in a plane. Although not shown in FIG. 3, also on the right side of the screen, a light shielding layer is formed so as to overlap with the end of the signal line electrode disposed at the rightmost end.

The light-shielding layer 117 can be made of a material other than a semiconductor, for example, the same metal material as the scanning line electrode 105, but may cause a short circuit with the signal line electrode 104 or the scanning line electrode 105. Further, it can be formed of a resin layer colored black with a pigment, but the number of steps for forming the resin layer further increases. However, when the light-shielding layer 117 is formed of a semiconductor layer, no short circuit occurs with other electrodes,
106 can be formed in the same step.

The transmittance of the light shielding layer 117 is desirably low, and desirably at least 50% or less.

An insulating film 119 is formed on the signal line electrode 104, and a pixel electrode 107 is formed thereon. The pixel electrode 107 is a pixel electrode disposed at the leftmost end of the screen, and is formed so as to extend outward (to the left in the drawing) so that the end overlaps with the signal line electrode 104. That is, in the liquid crystal display device 20 shown in FIG. 3, the insulating film 119 is formed on the signal line electrode 104 of the array substrate 100, and the pixel electrode 107 is formed on the insulating film 119.
It has a pixel-placed structure formed by spreading outward until it overlaps with the signal line electrode 104 of No. 00.

On the other hand, the opposite substrate 200 is the array substrate 10
It is composed of a transparent glass substrate 201 like 0,
A color filter 110 and a display area 103a are provided on its surface.
A black matrix (BM) 120 that shields the light from surrounding areas is formed. The black matrix 120 shown in FIG. 3B is a black matrix formed to shield the outside of the pixels at the outermost periphery of the display area 103a from light. On the color filter 110 and the black matrix 120, a counter electrode 203 large enough to cover the display area 103a is formed.

An alignment film 121 is formed on the outermost surfaces of the array substrate 100 and the counter substrate 200, and a liquid crystal layer 400 is filled between them.

The liquid crystal display device 20 constructed as described above
According to the above, even when the signal line electrode 104 functioning as a black matrix on the array substrate 100 and the black matrix 120 formed on the surface of the counter substrate 200 have little planar overlap, the signal line electrode 104 is formed on the array substrate 100 side. The light-shielding layer 117 suppresses light leakage occurring at the end of the display area, and makes light leakage less visible to the outside. Therefore, even when a pixel-placed structure is used to increase the aperture ratio, a significant reduction in screen quality due to light leakage does not occur, and a liquid crystal display device with excellent screen quality can be realized. Further, in a liquid crystal display device having a pixel-mounted structure, it is not necessary to increase the alignment accuracy between the signal line electrodes of the array substrate and the black matrix of the opposing substrate. Various restrictions can be eliminated.

The countermeasure against light leakage in the second embodiment is described in the first embodiment.
As described above, it is also effective in the case where a gap is generated between the display area end of the array substrate 100 and the display area end of the counter substrate 200 due to the difference in the amount of expansion between the two substrates.

[Third Embodiment] In a third embodiment, as in the second embodiment, a countermeasure for light leakage in a liquid crystal display device having a pixel-top structure will be described.

FIG. 4 is a configuration diagram of the liquid crystal display device according to the third embodiment. FIG. 4A is a schematic plan view, and FIG.
Shows partial sectional views of the display area end A. In FIG. 4, the same parts as those in FIGS. 1, 2 and 3 are denoted by the same reference numerals. In addition, the illustration and description of the parts described in the first and second embodiments are omitted as appropriate.

The basic configuration of the liquid crystal display device 30 is substantially the same as that of the first and second embodiments. The array substrate 100, the counter substrate 200, and the liquid crystal layer 40 sandwiched between these substrates are provided.
0 is provided.

The array substrate 100 is a transparent glass substrate 10
1, an interlayer insulating film 118 is formed on the surface thereof, and the signal line electrodes 104a to 104
c is formed. The signal line electrode 104a is a signal line electrode arranged at the leftmost end of the screen.
Is formed so as to overlap the edge of the black matrix 120 arranged on the counter substrate 200 side in a planar manner. Therefore, the signal line electrode 104a
Are formed wider than the other signal line electrodes 104b and 104c. That is, although the width of the normal signal line electrode is about 10 μm, the signal line electrode 104a disposed on the leftmost side of the screen has a large alignment margin with the black matrix 120 disposed on the counter substrate 200 side. In addition, it is formed so as to be wider than the other signal line electrodes 104b and 104c by several μm or more.
Note that the width of the signal line electrode 104b is desirably further increased by 10 μm or more than that of a normal signal line electrode.

Although not shown in FIG. 4, also on the right side of the screen, the rightmost signal line electrode is formed wider than the other signal line electrodes.

An insulating film 119 is formed on the signal line electrodes 104a to 104c, and a pixel electrode 107 is further formed thereon.
Are formed. Of the pixel electrodes 107, the pixel electrode 107 disposed at the leftmost end of the screen is positioned outside (left side in the figure) such that the end overlaps the signal line electrode 104a.
Spread out and formed. That is, in the liquid crystal display device 30 shown in FIG. 4, the insulating film 119 is formed on the signal line electrode 104 of the array substrate 100, and the pixel electrode 107 is outwardly placed on the insulating film 119 until it overlaps with the signal line electrode 104 of the array substrate 100. It has a pixel-placed structure formed by spreading.

On the other hand, the opposite substrate 200 is the array substrate 10
It is composed of a transparent glass substrate 201 like 0,
A color filter 110 and a display area 103a are provided on its surface.
A black matrix (BM) 120 that shields the light from surrounding areas is formed. The black matrix 120 shown in FIG. 4B is a black matrix formed to shield the outside of the pixels on the outermost periphery of the display area 103a from light. On the color filter 110 and the black matrix 120, a counter electrode 203 large enough to cover the display area 103a is formed.

An alignment film 121 is formed on the outermost surfaces of the array substrate 100 and the counter substrate 200, and a liquid crystal layer 400 is filled between them.

The liquid crystal display device 30 configured as described above
According to this, even when the planar overlap between the signal line electrode 104 functioning as a black matrix on the array substrate 100 and the black matrix 120 formed on the surface of the counter substrate 200 is small, the leftmost end of the array substrate 100 ( And the signal line electrode 104a disposed at the right end) suppresses light leakage occurring at the end of the display area, making it difficult for the light leakage to be seen outside. Therefore, even when a pixel-placed structure is used to increase the aperture ratio, a significant reduction in screen quality due to light leakage does not occur, and a liquid crystal display device with excellent screen quality can be realized. Further, in a liquid crystal display device having a pixel-mounted structure, it is not necessary to increase the alignment accuracy between the signal line electrodes of the array substrate and the black matrix of the opposing substrate. Various restrictions can be eliminated.

The countermeasure against light leakage in the third embodiment is described in the first embodiment.
As described above, it is also effective in the case where a gap is generated between the display area end of the array substrate 100 and the display area end of the counter substrate 200 due to the difference in the amount of expansion between the two substrates.

[0055]

According to the first aspect of the present invention, a gap is generated between the display area end of the array substrate and the display area end of the counter substrate due to a difference in the amount of expansion between the two substrates when the two substrates are bonded to each other. Even if it does, light leakage that occurs at the edge of the display area due to black display by the light-shielding electrode is suppressed, so that light leakage hardly appears to the outside. Therefore, it is possible to realize a liquid crystal display device having excellent screen quality without causing a significant decrease in screen quality due to light leakage.

According to the second aspect of the present invention, even when the signal line electrode functioning as a black matrix on the array substrate and the black matrix formed on the surface of the opposing substrate have little planar overlap, the signal line electrode is formed on the array substrate side. Since the light leakage generated at the end of the display area is suppressed by the light shielding layer, the light leakage hardly appears to the outside. Therefore, even when a pixel-placed structure is used to increase the aperture ratio, a significant reduction in screen quality due to light leakage does not occur, and a liquid crystal display device with excellent screen quality can be realized. In addition, even in the case of a pixel-mounted structure, it is not necessary to increase the alignment accuracy between the signal line electrodes of the array substrate and the black matrix of the counter substrate. Restrictions can be eliminated.

When the width of the signal line electrode disposed at the end of the display area is formed to be wider than the width of other signal line electrodes, the signal functioning as a black matrix on the array substrate is obtained. Even when the planar overlap between the line electrode and the black matrix formed on the surface of the counter substrate is small, light leakage generated at the end of the display area by the signal line electrode disposed at the leftmost (and rightmost) end of the array substrate. Is suppressed, so that light leakage hardly appears outside.
Therefore, even when a pixel-placed structure is used to increase the aperture ratio, a significant reduction in screen quality due to light leakage does not occur, and a liquid crystal display device with excellent screen quality can be realized. In addition, even in the case of a pixel-placed structure, it is not necessary to increase the alignment accuracy between the signal line electrodes of the array substrate and the black matrix of the counter substrate. Restrictions can be eliminated.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a liquid crystal display device according to a first embodiment.

FIG. 2 is a partial sectional view of FIG.

FIG. 3 is a configuration diagram of a liquid crystal display device according to a second embodiment.

FIG. 4 is a configuration diagram of a liquid crystal display device according to a third embodiment.

[Explanation of symbols]

100 ... array substrate, 103a ... display area, 103b ...
Non-display area 104: signal line electrode, 105: scanning line electrode, 106: T
FT 107: pixel electrode, 110: color filter, 115:
Light-shielding electrode 117: light-shielding layer, 200: counter substrate, 202: frame, 2
03 ... Counter electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA34Y FC02 FC10 FC26 FD04 FD22 GA13 HA07 LA03 LA16 2H092 JA24 JB13 JB54 NA07 NA25 NA27 NA30 PA09 QA07 5C094 AA16 BA03 BA43 CA19 EA04 EA07 EB05 ED15 HA08

Claims (2)

[Claims] A first substrate on which a plurality of pixel electrodes are regularly arranged in a display area; a second substrate on which a counter electrode opposed to the plurality of pixel electrodes is formed; In a liquid crystal display device comprising a sandwiched liquid crystal material, a light-shielding electrode is formed on the first substrate so as to cover the periphery of the display region, and the light-shielding electrode and the counter electrode are displayed during image display. A liquid crystal display device, which always supplies a black display potential between the two. 2. A plurality of pixel electrodes are regularly arranged in a display area, and these pixel electrodes are connected via switch elements to respective intersections of a plurality of scanning line electrodes and a plurality of signal line electrodes which cross each other. A liquid crystal display device comprising a first substrate, a second substrate on which a counter electrode facing the pixel electrode is formed, and a liquid crystal material sandwiched between the substrates. A liquid crystal display device, wherein a light-shielding layer made of a linearly formed semiconductor layer is arranged outside the signal line electrode arranged so as to overlap the outer edge of the signal line electrode in a plane. .