HK1086076B

HK1086076B - Vertically alignment liquid crystal display device

Info

Publication number: HK1086076B
Application number: HK06106003.6A
Authority: HK
Inventors: 亮太水迫
Original assignee: Ortus Technology Co., Ltd.
Priority date: 2004-07-16
Filing date: 2006-05-25
Publication date: 2009-05-29

Description

Vertical alignment liquid crystal display device

Technical Field

The present invention relates to a vertical alignment type liquid crystal display device.

Background

A conventional TFT liquid crystal panel is composed of a TFT (thin Film transistor) substrate, a cf (color filter) substrate, and a liquid crystal layer sandwiched between these substrates. As the liquid crystal material sealed between the TFT substrate and the CF substrate, a material exhibiting positive dielectric anisotropy in a TN (Twisted Nematic) display is used. A vertical alignment type TFT liquid crystal display element, which orients a director (molecular long axis direction) of liquid crystal toward a direction perpendicular to a substrate in a state without an electric field, is proposed using a liquid crystal display element of a material exhibiting negative dielectric anisotropy.

A vertical alignment type TFT liquid crystal display element constitutes a liquid crystal cell by enclosing liquid crystal exhibiting negative dielectric anisotropy between a pair of substrates arranged in opposition to each other.

On one of the pair of substrates, a pixel electrode is formed for each pixel, and on the other substrate, a common (counter) electrode is formed so as to face the plurality of pixel electrodes, and one pixel is formed by the respective pixel electrodes, the facing portions of the common electrode, and the liquid crystal therebetween. On each substrate, a vertical alignment film is formed to cover the pixel electrode and the common electrode, and the vertical alignment film is subjected to rubbing (rubbing) treatment for determining a direction in which the liquid crystal is tilted when a voltage is applied between the pixel electrode and the common electrode.

When no voltage is applied between the pixel electrode and the common electrode, the potentials of the common electrode and the pixel electrode are the same, so that no electric field is formed between the pixel electrode and the common electrode, and the liquid crystal molecules are aligned vertically with respect to the substrate by the negative dielectric anisotropy and the action of the vertical alignment film.

When a voltage is applied between the pixel electrode and the common electrode, the liquid crystal molecules tilt due to an electric field formed between the pixel electrode and the common electrode, and when a sufficiently high voltage is applied between the pixel electrode and the common electrode, the liquid crystal molecules are aligned substantially horizontally with respect to the substrate.

In this case, when an electric field is applied between the pixel electrode and the common electrode, the liquid crystal molecules are aligned in one direction by the electric field formed between the pixel electrode and the common electrode, and therefore, the viewing angle dependence of the contrast is large, and the viewing angle characteristics are poor.

In order to obtain a wide viewing angle characteristic, it has been proposed that a plurality of domains (domains) are formed in each pixel in a multi-directional alignment in a vertical alignment type liquid crystal display device. For example, as described in japanese patent No. 2565639, a liquid crystal display device has been proposed in which X-shaped openings are formed in a common electrode, and when a voltage is applied between two opposing electrodes, liquid crystal molecules are aligned in such a manner that they fall in four directions toward the center of the X-shaped openings in one pixel.

In this liquid crystal display device, the common electrode is formed larger than the pixel electrode, and when a voltage is applied between the pixel electrode and the common electrode, a vertical electric field is generated in a portion of the pixel region where the pixel electrode and the common electrode face each other, an oblique electric field is generated in a peripheral portion of the pixel electrode, and a discontinuous electric field portion is formed in a portion of the common electrode where the opening (slit) is formed, whereby liquid crystal molecules are arranged so as to fall toward the center of the X-shaped opening for each pixel. That is, in this liquid crystal display device, liquid crystal molecules are aligned so as to be inclined in 4 directions for each region divided by the X-shaped openings for each pixel.

However, in the liquid crystal display device, since the regions having different alignment directions are formed by the X-shaped apertures formed in the respective pixels, the X-shaped apertures need to be formed wide enough to prevent the interaction between the regions. For this reason, there are the following problems: in each pixel, the area of the aperture (slit) that cannot be controlled by the electric field increases, the area of the common electrode decreases, and the aperture ratio decreases.

Disclosure of Invention

An object of the present invention is to provide a liquid crystal display element having a wide viewing angle, high transmittance and high contrast.

In order to achieve the above object, a liquid crystal display device according to a first aspect of the present invention includes:

a substrate;

another substrate disposed opposite to the one substrate with a predetermined gap therebetween;

at least one first electrode formed on one of the surfaces of the one substrate and the other substrate facing each other;

a plurality of second electrodes formed on the other of the facing surfaces, each of the second electrodes having an opening for dividing each of the pixels into a plurality of sub-pixel regions, each of the second electrodes forming a plurality of pixels as a display minimum unit region in a region facing the first electrode;

vertical alignment films formed on the inner surfaces of the first substrate and the second substrate facing each other, the inner surfaces of the first substrate and the second substrate having the first and second electrodes formed thereon, respectively;

a liquid crystal layer sealed between the substrates and having negative dielectric anisotropy; and

and an auxiliary electrode formed in a peripheral region surrounding at least the second electrode.

The liquid crystal display element according to claim 1 includes the opening provided in the second electrode and dividing each of the pixels into the plurality of sub-pixel regions, and the auxiliary electrode formed in the peripheral region surrounding at least the second electrode, and the liquid crystal molecules are arranged in a continuous radial shape in each of the sub-pixel regions from the periphery to the center of the sub-pixel region, so that the position of the center of the radial alignment can be stabilized, and the alignment of each of the pixels can be stabilized, and display unevenness does not occur.

In the liquid crystal display device, the auxiliary electrode is preferably formed to surround each of a plurality of sub-pixel regions defined by the opening, and the auxiliary electrode is preferably provided to correspond to a peripheral portion of the second electrode and the opening.

Preferably, the opening is formed in the second electrode to which the active element is connected, and includes a plurality of slits extending from a center to an outer peripheral edge of each of the second electrodes and connected to each other at a center of the pixel electrode.

In this case, it is preferable that the auxiliary electrode is formed on the surface of the other substrate, and the second electrode is formed on an insulating film covering the auxiliary electrode of the other substrate.

Preferably, a voltage applied to the first electrode formed on one substrate is applied to the auxiliary electrode.

In this case, since the auxiliary electrode is provided in correspondence with the opening and the voltage applied to the first electrode is applied to the auxiliary electrode, no electric field is applied to the region corresponding to the opening, the effect of the opening formed in the second electrode is increased, and the width of the opening can be narrowed. As a result, the area of the second electrode in each pixel becomes large, the portion that cannot be controlled by the electric field in each pixel becomes small, the aperture ratio of the pixel becomes large, and the aperture ratio becomes high.

A liquid crystal display device according to claim 2 of the present invention includes:

a substrate;

at least one first electrode formed on a surface of the one substrate facing the other substrate;

a plurality of second electrodes formed on a surface of the other substrate facing the one substrate, each of the plurality of second electrodes having a slit for dividing each of the plurality of pixels into a plurality of sub-pixel regions, each of the plurality of second electrodes being defined by a region facing the first electrode;

vertical alignment films formed on a surface of the one substrate on which the first electrode is formed and a surface of the other substrate on which the second electrode is formed, respectively;

a liquid crystal layer sealed between the substrates and having negative dielectric anisotropy;

a first auxiliary electrode formed in a peripheral region surrounding at least the second electrode on a surface of the other substrate on which the second electrode is provided, the first auxiliary electrode being configured to align liquid crystal molecules of the liquid crystal layer located in the periphery of the pixel such that major axes of the liquid crystal molecules are inverted from the periphery to the center by an electric field applied between the first auxiliary electrode and the second electrode; and

and a second auxiliary electrode formed in a region corresponding to the slit on the surface of the other substrate on which the second electrode is provided, the second auxiliary electrode being configured to align liquid crystal molecules of the liquid crystal layer located in the periphery of the sub-pixel region such that the major axes of the liquid crystal molecules are inverted from the periphery to the center for each of the plurality of sub-pixel regions by an electric field applied between the second auxiliary electrode and the second auxiliary electrode.

In the liquid crystal display device according to claim 2, the liquid crystal molecules of each pixel are arranged in a continuous radial pattern in each sub-pixel region from the periphery of each sub-pixel region toward the center of the opening, and the position of the center of the radial alignment can be stabilized, so that the alignment of each pixel can be stabilized and display unevenness does not occur.

In the liquid crystal display device, it is preferable that the slits include a plurality of missing portions formed in the second electrode so as to extend from the center to the outer peripheral edge of each pixel and to be connected to each other at the center of the pixel region, and it is further preferable that the slits are formed in the second electrode to which the active element is connected.

Preferably, the first and second auxiliary electrodes are formed on the other substrate surface, the second electrode is formed on the first and second auxiliary electrodes covering the other substrate, and the first auxiliary electrode and the second auxiliary electrode are integrally connected to each other on the other substrate surface.

In addition, the first and second auxiliary electrodes are preferably set to a potential lower than that of the second electrode, and more specifically, the first and second auxiliary electrodes are preferably set to a potential equal to that of the first electrode facing the second electrode.

Preferably, the first auxiliary electrode includes a compensation capacitor electrode overlapping a peripheral portion of the second electrode to form a compensation capacitor between the first auxiliary electrode and the second electrode, the second auxiliary electrode has a width larger than a width of the slit of the second electrode, a region of the second auxiliary electrode overlapping the second electrode forms a compensation capacitor between the second electrode, and the first and second auxiliary electrodes are formed of a transparent conductive film.

A liquid crystal display device according to claim 3 of the present invention includes:

a substrate;

a plurality of second electrodes formed on the other of the surfaces facing each other, each of the second electrodes forming a plurality of pixels as a display minimum unit region in a region facing the first electrode;

a dividing member provided on the second electrode, and dividing each pixel into a plurality of sub-pixel regions;

and an alignment member provided on the other substrate, the alignment member aligning, for each of the plurality of sub-pixel regions, liquid crystal molecules of the liquid crystal layer located in the periphery of the sub-pixel region such that the long axes of the liquid crystal molecules are inverted from the periphery to the center.

In the liquid crystal display device according to claim 3, the liquid crystal molecules of each pixel are arranged in a continuous radial pattern in each sub-pixel region from the periphery of each sub-pixel region toward the center of the opening, and the position of the center of the radial alignment can be stabilized, so that the alignment of each pixel can be stabilized and display unevenness does not occur.

In the liquid crystal display device, it is preferable that the dividing member includes a slit formed in the second electrode, and the alignment member includes an auxiliary electrode formed in a region corresponding to a member for dividing the pixel into sub-pixel regions, and a peripheral region surrounding at least the second electrode on a surface of the other substrate on which the second electrode is provided.

Drawings

Fig. 1 is a sectional view showing a structure of a liquid crystal display device according to embodiment 1 of the present invention.

Fig. 2A to C show a structure of a portion corresponding to one pixel of a liquid crystal display device according to embodiment 1 of the present invention, fig. 2A is a plan view, fig. 2B is a cross-sectional view taken along line 2B-2B of fig. 2A, and fig. 2C is a cross-sectional view taken along line 2C-2C of fig. 2A.

Fig. 3A to B schematically show an electric field generated in a liquid crystal layer of the liquid crystal display device of fig. 1 and alignment of liquid crystal molecules, fig. 3A is an equipotential diagram, and fig. 3B is a diagram showing an arrangement state of liquid crystal molecules.

Fig. 4 is a drive voltage waveform diagram showing waveforms of drive voltages applied to the respective electrodes of the liquid crystal display element of fig. 1.

Fig. 5A to B show the alignment state of the liquid crystal molecules of each pixel, fig. 5A is a schematic view showing the alignment state of the liquid crystal molecules located in the peripheral portion of each sub-pixel region, and fig. 5B is a schematic view showing the alignment state of the liquid crystal molecules of each sub-pixel region in a planar manner.

Fig. 6A to C each show a structure of a portion corresponding to one pixel of a liquid crystal display element according to embodiment 2 of the present invention, where fig. 6A is a plan view and fig. 6B is a cross-sectional view taken along line 6B-6B and shown in fig. 6A. Fig. 6C is a cross-sectional view taken along line 6C-6C of fig. 6A.

Detailed Description

A liquid crystal display device according to an embodiment of the present invention will be described with reference to the following drawings.

Fig. 1 is a sectional view showing the structure of a vertical alignment liquid crystal display device according to embodiment 1 of the present invention, and fig. 2A is a plan view showing one pixel structure of the liquid crystal display element.

As shown in fig. 1 and 2A, the liquid crystal panel 100 includes: a pair of substrates 10, 20; a pixel electrode 30 and a counter electrode 40 formed on the inner surfaces of the substrates facing each other; alignment films 50, 50 formed on the surfaces of these electrodes; a sealing member 90 for joining the pair of substrates 10 and 20; and a liquid crystal layer 60 sealed between the pair of substrates. The liquid crystal display element is composed of a liquid crystal panel 100 and a pair of polarizing plates 70 and 80. The polarizing plates 70 and 80 are disposed on the outer sides of the pair of substrates 10 and 20 of the liquid crystal panel 100 so as to sandwich the substrates.

The counter electrode 40 and a color filter, not shown, are formed on the inner surface of one substrate 10 of the pair of substrates 10 and 20.

The other substrate 20 has formed on its inner surface: a pixel electrode 30; a TFT element 31 connected to the pixel electrode 30, for applying an image signal supplied from the outside to the pixel electrode 30; a drain wiring 32 for supplying an image signal to the TFT element 31; an auxiliary electrode 33 for controlling and stabilizing the alignment of liquid crystal molecules of each pixel and forming a compensation Capacitance (CS) with the pixel electrode 30; a gate line 34 for supplying a gate signal for controlling an operation of the TFT element 31 to the TFT element 31; a gate insulating film 35 covering the gate electrode of the TFT element 31; an insulating film 36 covering the drain wiring 32; and a vertical alignment film 50 covering the surface of these films.

Although not shown in detail, the TFT element 31 is an inverted staggered (starter) Thin Film Transistor (Thin Film Transistor) formed on a substrate.

The pixel electrode 30 is formed of a substantially rectangular transparent electrode made of an ito (indium Tin oxide) film or the like containing indium oxide as a main component. The pixel electrode 30 is defined by a region facing the counter electrode 40 as a region of one pixel which is a minimum unit for forming a pixel. An opening portion having a narrow width is formed in the pixel electrode 30, and the opening portion is used to divide each pixel into a plurality of sub-pixel regions. The opening is formed by a plurality of slits 30a extending from the center of the pixel electrode 30 to the outer peripheral edge and connected to each other at the center of the pixel electrode 30. In this embodiment, a slit 30a is formed in the pixel electrode 30, the slit 30a extends in the longitudinal and lateral directions of the central portion of the pixel electrode 30 to cut the pixel electrode 30, and the one pixel is divided into 4 sub-pixel regions by the slit 30 a.

The drain line 32 is formed of an aluminum line or the like extending in the column direction for each pixel column. The drain line 32 is connected to the drain electrode of the TFT element 31 in the same pixel column, and supplies an image signal from the column driver to the pixel electrode 30 via the TFT element 31 that is turned on.

The auxiliary electrode 33 is made of aluminum or the like, and is formed around the pixel electrode 30 so that a part thereof overlaps with the outer peripheral edge portion of the pixel electrode 30 with a gate insulating film 35 interposed therebetween. The auxiliary electrode 33 is formed under the pixel electrode 30 corresponding to the slit 30a, and is wider than the slit 30a, and partially overlaps the peripheral edge. The auxiliary electrode 33 is maintained at a predetermined potential lower than that of the pixel electrode 30, and more preferably, set to the same potential as that of the counter electrode 40, and a compensation Capacitor (CS) is formed between the auxiliary electrode 33 and the pixel electrode 30 in parallel with a pixel capacitor formed by each of the pixel electrode 30, the counter electrode 40, and the liquid crystal 60.

The gate line 34 is made of an aluminum line or the like formed to extend in the row direction for each pixel row, and is insulated from other electrodes by a gate insulating film 35. The gate wiring 34 is connected to the gate electrode of the TFT element 31 in the corresponding pixel row, supplies a scanning signal to the TFT element 31, and controls ON/OFF (ON/OFF) of the TFT element 31.

The gate insulating film 35 is an insulating film formed on the substrate 20 on which the gate electrode of the TFT element 31, the gate wiring 34, and the auxiliary electrode 33 are formed, and is formed of, for example, a silicon nitride film. The gate insulating film 35 electrically separates a gate electrode, not shown, of the TFT element 30 from a semiconductor layer and source/drain electrodes facing the gate electrode. The TFT elements 31 have source electrodes connected to the corresponding pixel electrodes 30 and drain electrodes connected to the corresponding drain wirings 32.

The insulating film 36 is an insulating film covering the drain wiring 32 and formed between the pixel electrode 30 and the pixel electrode 30 of the adjacent pixel, and is formed of, for example, a silicon nitride film.

The vertical alignment film 50 is formed of, for example, a hexamethyldisiloxane (ヘキサメチルジシロキサン) polymer film formed by cvd (chemical Vapor deposition). The vertical alignment film 50 is formed to cover the pixel electrode 30 formed on the substrate 10 and the counter electrode 40 formed on the substrate 20, respectively. Further, a liquid crystal 60 is sealed between the opposing vertical alignment films 50. Further, no rubbing (rubbing) is formed on the vertical alignment film 50, and the liquid crystal molecules in the vicinity of the surface are vertically aligned in the absence of an electric field by the alignment regulating force.

Next, a method for manufacturing the liquid crystal display element having the above-described configuration will be described.

An aluminum film is formed on the glass substrate 20, and the aluminum film is patterned to form the gate electrode of the TFT element 31, the gate wiring 34, and the auxiliary electrode 33 (including a wiring connected to the auxiliary electrode 33). Next, the gate insulating film 35 is formed using CVD. Next, a semiconductor layer, a source electrode, and a drain electrode of the TFT element 31 are formed on the gate insulating film 35.

Next, an ITO film is formed on the gate insulating film 35 by sputtering. The ITO film is etched and patterned (patterned) leaving a portion of the formed ITO film constituting the pixel region, thereby obtaining a pixel electrode 30, and the pixel electrode 30 is formed with a narrow slit 30a extending from the center of the pixel toward the peripheral portion of the pixel region.

A drain wiring 32 is formed on the gate insulating film 35 apart from the outer peripheral edge of the pixel electrode 30 and connected to the drain region of the TFT element 31. An insulating film 36 is formed on the gate insulating film 35 so as to cover the drain wiring 32 formed on the non-pixel region around the pixel electrode 30.

Next, the vertical alignment film 50 is formed over the entire surface by CVD, coating, or the like.

The TFT substrate 20 formed as described above and the counter substrate 10 on which the counter electrode, the color filter, and the like are formed are arranged to face each other with a not-shown spacer interposed therebetween, and the periphery is sealed with a sealing material 90 to form a liquid crystal cell. Next, liquid crystal 60 is injected into the liquid crystal cell, and an injection port not shown in the drawing is sealed. Polarizing plates 70, 80 are also arranged on the outer faces of the substrate 20 and the substrate 10 to manufacture a liquid crystal display element.

Next, the movement of the liquid crystal in the pixel having the above-described configuration is described.

One pixel defined by a region where one pixel electrode 30 and the opposite electrode 40 are opposite to each other is divided into 4 sub-pixel regions by a plurality of slits 30a formed in the pixel electrode 30. The periphery of each sub-pixel region is surrounded by the auxiliary electrode 33, and when a voltage is applied between the pixel electrode 30 and the auxiliary electrode 33, a lateral electric field is generated at four sides of each sub-pixel.

Fig. 3A and 3B schematically show the electric field and the alignment of the liquid crystal molecules in the vicinity of the slit 30a in the cross-sectional structure shown in fig. 2B. As shown in fig. 4, a driving voltage VD of 3.0 to 9.0V is applied to the pixel electrode 30 and a driving voltage VC of-2.0 to 04.0V is applied to the auxiliary electrode 33 and the opposite electrode 40 with a pulse frequency of 16.6 ms. A potential difference of 5.0V is generated between the pixel electrode 30 and the counter electrode 40 and the auxiliary electrode 33, and a transverse electric field is generated at the edge portion of the slit 30a of the pixel electrode 30 by the potential difference, and a transverse electric field is also generated between the edge portion around the pixel electrode 30 and the auxiliary electrode 33. The horizontal electric field becomes an oblique electric field from the edge portion of the pixel electrode 30 to the inside of the pixel electrode 30, and a position sufficiently apart from the edge of the electrode becomes a vertical electric field. This state is represented by an equipotential line in fig. 3A.

The liquid crystal molecules 60a in the peripheral portion of the sub-pixel region of the pixel electrode 30 divided by the slit 30a are aligned so that the long axis direction (director) is inclined along the equipotential lines shown in fig. 3A as shown in fig. 3B so as to be perpendicular to the lateral electric field in the peripheral edge and the direction of the electric field inclined inward of the peripheral edge. As shown in fig. 5A schematically illustrating the operation of the liquid crystal molecules 60a in each sub-pixel region, the liquid crystal molecules 60a in the peripheral portion of each sub-pixel region move while falling inside each pixel region. Further, since the liquid crystal molecules in the peripheral portion are arranged so as to fall toward the center, the liquid crystal molecules 60a in the central portion of each sub-pixel region are uniformly subjected to the intermolecular force from the periphery and are aligned perpendicularly to the substrate surface. When each sub-pixel region is viewed from the cross-sectional direction, as shown in fig. 3B, the liquid crystal molecules 60a are arranged as follows: outside the outer peripheral edge of the pixel electrode 30 and the slit 30a of the pixel electrode 30, the director thereof is oriented substantially perpendicularly to the substrate surface. In addition, the liquid crystal molecules 60a are arranged as follows: the director is inclined inward from the outer peripheral edge of the pixel and the edge of the slit 30a, and is substantially parallel to the substrate surface on a sufficiently inward side. Then, in the central portion of each quadrant, the liquid crystal molecules 60a align the director in a direction perpendicular to the substrates.

As shown in fig. 5B schematically illustrating the alignment state of the liquid crystal molecules 60a in each sub-pixel region, when each sub-pixel region is viewed in the planar direction of the pixel electrode 30, the liquid crystal molecules 60a are arranged as follows: the director of each of the pixel regions of the pixel electrode 30 is divided by the slit 30a, and the liquid crystal molecules vertically aligned from the approximate center of each of the sub-pixel regions are radially aligned toward the periphery.

As described above, the pixel electrode 30 is formed with the slit 30a extending from the center of the pixel toward the periphery of the pixel, and the pixel is divided into a plurality of sub-pixel regions. Then, for each of the divided sub-pixel regions, liquid crystal molecules are arranged from the outer peripheral edge thereof toward the center thereof at the divided sub-pixel regions by an electric field generated in accordance with a voltage applied between the pixel electrode 30 and the auxiliary electrode 33 at the peripheral portion thereof. As a result, liquid crystal alignment discontinuous domains are formed in each of the divided sub-pixel regions. Further, since the auxiliary electrode 33 is disposed at the portion corresponding to the slit 30a, the alignment of the liquid crystal at the quadrant peripheral portion is stabilized, and as a result, the alignment of the liquid crystal molecules formed in each of the divided sub-pixel regions is stabilized. Therefore, roughness and unevenness in display can be eliminated. Further, since the liquid crystal molecules are aligned toward the domain center in each domain, the viewing angle characteristics are also improved.

Further, on the substrate side of the slit 30a for dividing the pixel into a plurality of sub-pixel regions, an auxiliary electrode 33 as an auxiliary electrode is formed, and it is preferable that the potential of the auxiliary electrode 33 is lower than the potential of the pixel electrode 30 and equal to the potential of the counter electrode 40. Thus, since the change in the electric field at the outer peripheral edge of the pixel electrode 30 based on the gap 30a is clear, the width of the gap 30a can be reduced, and as a result, the area in which the liquid crystal molecules operate can be controlled by the electric field in one pixel can be increased, and the aperture ratio can be improved.

The present invention is not limited to the above-described embodiments, and applications and variations thereof are arbitrary.

For example, in embodiment 1, the auxiliary electrode 33 is formed of a metal film, but the auxiliary electrode 33 may be formed of a metal film such as aluminum or the like at a portion corresponding to the peripheral portion of the pixel electrode 30, and the auxiliary electrode 33 formed of a transparent conductive film at a portion corresponding to the slit 30a inside the pixel electrode 30.

In this way, the auxiliary electrode 33 is formed by the metal film in the peripheral portion of the pixel and the transparent conductive film inside, and thus light transmitted through the inside of the pixel electrode 30 is not blocked by the auxiliary electrode 33, so that the transmittance of each pixel is improved, and bright display can be obtained.

(embodiment mode 2)

In embodiment 1, the auxiliary electrode 33 is formed of aluminum or the like, but the auxiliary electrode 33 may be formed of a transparent electrode formed of a transparent conductive film. In this case, the liquid crystal display element has a cross-sectional structure as shown in fig. 6A to 6B. The same components as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the quadrant wires 32 are formed on the substrate 20, and the insulating film 38 made of a silicon nitride film is formed to cover the quadrant wires 32. On the insulating film 38, the TFT element 31, the auxiliary electrode 37, and the gate wiring 34 are formed as in embodiment 1, and the transparent pixel electrode 30 is formed thereon with the gate insulating film 35.

The auxiliary electrode 37 is formed of a transparent electrode such as an ITO film containing indium oxide as a main component, and is connected to a metal wiring 37a made of aluminum or the like provided in the vicinity of the pixel electrode 30.

The quadrant wiring 32 is connected to a connection wiring 32a on the gate insulating film 35 via a through hole 38a provided in the insulating film 38 and the gate insulating film 35, and the connection wiring 32a is connected to a quadrant electrode of the TFT element 31.

A method for manufacturing the liquid crystal display device having the above-described structure will be described.

A quadrant wiring 32 is formed on the substrate 20 in a region away from the pixels. Next, an insulating film 38a is formed on the substrate 20. Next, an aluminum film is formed over the insulating film 38, and patterned to form the gate electrode of the TFT element 31 and the gate wiring 34.

Next, an ITO film is formed on the insulating film 38 by sputtering. The ITO film is etched to be patterned, thereby forming the auxiliary electrode 37.

Then, the gate insulating film 35 is formed by CVD. Next, a semiconductor layer of the TFT element 31 is formed on the gate insulating film 35, and a drain electrode and a source electrode are formed.

Next, an ITO film is formed on the gate insulating film 35 by sputtering. The pixel electrode 30 is obtained by leaving a portion of the formed ITO film constituting the pixel region and etching the ITO film to perform patterning, and the pixel electrode 30 is formed with a narrow slit 30a extending from the center portion of the pixel to the peripheral portion of the pixel. The connection wiring 32a made of metal is formed so as to be connected through a via hole 38a provided on the insulating film 38 and the insulating film 35, and after being connected to the quadrant electrode of the TFT element 31, the insulating film 36 is formed at a portion other than the pixel region. Next, an alignment film 50 is formed on the entire surface by CVD and sputtering.

As described above, in embodiment 2, as in embodiment 1, the slits 30a are formed in the pixel electrode 30 from the center of the pixel toward the periphery of the pixel, the pixel is divided into a plurality of sub-pixel regions, and the auxiliary electrode 37 is further disposed in the portion corresponding to the slits 30a, so that the alignment of the liquid crystal in the quadrant peripheral portion is stabilized, and as a result, the quadrant formation in which the arrangement of the liquid crystal molecules is stabilized for each of the divided sub-pixel regions is stabilized. Therefore, roughness and unevenness in display can be eliminated. In addition, since the liquid crystal molecules are aligned toward the domain center in each domain, the viewing angle characteristics are also improved.

In addition, the potential of the auxiliary electrode 37 as an auxiliary electrode formed on the substrate side of the slit 30a for dividing the pixel into a plurality of sub-pixel regions is set to be lower than the potential of the pixel electrode 30, and preferably, the potential of the auxiliary electrode 37 is equal to the potential of the counter electrode 40. Thus, since the change in the electric field at the outer peripheral edge of the pixel electrode 30 becomes clear, the width of the slit 30a can be narrowed, and as a result, the area in which the movement of the liquid crystal molecules can be controlled by the electric field in one pixel can be increased, and the aperture ratio can be increased.

Since the auxiliary electrode 37 is formed of a transparent conductive film, light can be transmitted through a region overlapping with the pixel electrode 30, and the entire area of the pixel electrode 30 becomes a region where the transmission of light can be controlled, so that the transmittance of the pixel is improved, and bright display can be obtained.

The present invention is not limited to the above-described embodiments, and applications, variations, and the like thereof are arbitrary.

For example, in the above embodiments, the slits 30a are formed along the longitudinal direction and the lateral direction from the center portion to the peripheral portion of the pixel electrode 30, but the slits 30a may be arranged to divide the pixel electrode 30 into substantially the same shape, and may be formed, for example, from the center portion to four corners of the pixel electrode 30 on the diagonal line of the pixel electrode 30. The number of sub-pixel regions divided by the slit is not limited to 4, and may be any integer of 2 or more.

Claims

1. A liquid crystal display element, characterized by comprising:

a substrate;

a plurality of second electrodes formed on the other of the facing surfaces, each of the second electrodes having an opening for dividing each of the pixels into a plurality of sub-pixel regions, each of the second electrodes being formed as a plurality of pixels serving as a display minimum unit region in a region facing the first electrode;

an auxiliary electrode provided corresponding to a peripheral area surrounding at least the second electrode and the opening of the second electrode on the other substrate surface on which the second electrode is formed, a part of the auxiliary electrode overlapping an edge of the second electrode and an edge of the opening of the second electrode, and the auxiliary electrode surrounding each pixel and a periphery of the sub-pixel area, the auxiliary electrode including a transparent conductive film provided on a portion of the peripheral area surrounding the second electrode overlapping the second electrode and a metal wiring provided so as to be connected to the transparent conductive film at a portion of the peripheral area other than the portion overlapping the second electrode, and a voltage being applied between the auxiliary electrode and the second electrode to generate a transverse electric field at four sides of each sub-pixel, the liquid crystal molecules of the liquid crystal layer located around the sub-pixel region are arranged such that their molecular long axes are inverted from the periphery to the center by the transverse electric field.

2. The liquid crystal display element according to claim 1, wherein a portion of the auxiliary electrode which overlaps with an edge of the opening of the second electrode is formed of a transparent conductive film.

3. The liquid crystal display element according to claim 1, wherein the opening includes a plurality of slits extending from a center to an outer peripheral edge of the opening for each of the second electrodes and connected to each other at a center portion of the second electrode.

4. The liquid crystal display element according to claim 1, further comprising an active element which is formed on the other substrate, connected to the second electrode, and applies an image signal supplied from outside to the second electrode;

the opening is formed in the second electrode connected to the active element.

5. The liquid crystal display element according to claim 1, wherein the auxiliary electrode is formed on a surface of the other substrate, and the second electrode is formed on an insulating film covering the auxiliary electrode of the other substrate.

6. The liquid crystal display element according to claim 1, wherein the first electrode is formed over the one substrate, and the auxiliary electrode is formed over the other substrate, and the same voltage as that of the first electrode is applied.

7. A liquid crystal display element, characterized by comprising:

a substrate;

a first auxiliary electrode formed in a peripheral region surrounding at least the second electrode on the other substrate surface on which the second electrode is formed, a part of the first auxiliary electrode overlapping an edge of a periphery of the second electrode, the first auxiliary electrode including a transparent conductive film disposed in a portion of the peripheral region surrounding the second electrode overlapping the second electrode and a metal wiring disposed in a portion of the peripheral region other than the portion overlapping the second electrode and connected to the transparent conductive film, the first auxiliary electrode being configured to align liquid crystal molecules of the liquid crystal layer located in a periphery of the pixel such that a major axis of the liquid crystal molecules is inverted from the periphery to a center by an electric field applied between the first auxiliary electrode and the second electrode; and

and a second auxiliary electrode formed of a transparent conductive film, a part of which is overlapped with the second electrode corresponding to the slit, in a region corresponding to the slit on the other substrate surface on which the second electrode is formed, wherein liquid crystal molecules of the liquid crystal layer located in the periphery of the sub-pixel region are arranged such that the major axes thereof are inverted from the periphery to the center for each of the plurality of sub-pixel regions by an electric field applied between the second auxiliary electrode and the second electrode.

8. The liquid crystal display element according to claim 7, wherein the slit includes a plurality of missing portions extending from a center to an outer peripheral edge of each of the pixels and connected to each other at a center portion of the pixel region.

9. The liquid crystal display element according to claim 7, further comprising an active element which is formed on the other substrate, connected to the second electrode, and applies an image signal supplied from outside to the second electrode;

the slit is formed on a second electrode connected to the active element.

10. The liquid crystal display element according to claim 7, wherein the first and second auxiliary electrodes are formed on the other substrate surface, and the second electrode is formed on the first and second auxiliary electrodes covering the other substrate.

11. The liquid crystal display element according to claim 7, wherein the first auxiliary electrode and the second auxiliary electrode are formed so as to be connected to each other on the other substrate surface.

12. The liquid crystal display element according to claim 7, wherein the first and second auxiliary electrodes are set to have a lower potential than the second electrode.

13. The liquid crystal display element according to claim 7, wherein the first and second auxiliary electrodes are set to the same potential as that of the first electrode facing the second electrode.

14. The liquid crystal display element according to claim 7, wherein the first auxiliary electrode includes a compensation capacitor electrode which overlaps with a peripheral portion of the second electrode and forms a compensation capacitor with the second electrode.

15. The liquid crystal display element according to claim 7, wherein a width of the second auxiliary electrode is formed to be wider than a width of a slit of the second electrode,

the region of the second auxiliary electrode overlapping the second electrode forms a compensation capacitance with the second electrode.

16. A liquid crystal display element, characterized by comprising:

a substrate;

an array member including an auxiliary electrode formed so as to surround the periphery of each pixel and the periphery of each sub-pixel region so as to overlap with the edge of the second electrode by applying a voltage between the auxiliary electrode and the second electrode, the auxiliary electrode including a transparent conductive film disposed in a portion of the other peripheral region on the other substrate surface on which the second electrode is formed so as to surround at least the peripheral region of the second electrode overlapping with the edge of the second electrode, a metal wiring disposed so as to be connected to the transparent conductive film in a portion of the peripheral region other than the portion overlapping with the second electrode, and a transparent conductive film disposed in a region corresponding to a member for dividing the pixel into sub-pixel regions, the array member generating a transverse electric field on four sides of each sub-pixel by applying a voltage between the array member and the second electrode, the liquid crystal molecules of the liquid crystal layer located in the periphery of the sub-pixel regions are arranged such that the long axes of the molecules of the liquid crystal layer are inverted from the periphery to the center of the liquid crystal layer for each of the plurality of sub-pixel regions by the transverse electric field.

17. The liquid crystal display element according to claim 16, wherein the dividing member includes a slit formed in the second electrode.