KR20050025446A - Liquid crystal display device - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to allow for a smooth formation of electric field and achieve improved response speed of liquid crystal alignment, by adopting a VA-IPS mode where a vertically aligned layer is formed on an upper substrate and a lower substrate opposed each other so that the liquid crystal is aligned in a vertical direction at an initial state where a voltage is not applied. An LCD comprises a lower substrate(80) and an upper substrate(90) opposed each other; a plurality of gate lines and date lines(82) intersecting each other in a vertical direction on the lower plate so as to define a pixel region; a plurality of first common electrodes(85) formed in the pixel region; a plurality of pixel electrodes(84) arranged alternately with the first common electrodes; a second common electrode(93) formed on the upper substrate; a first alignment layer(87) and a second alignment layer(95) aligned in a vertical direction on the lower substrate and the upper substrate; and a liquid crystal layer formed between the lower substrate and the upper substrate.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which the transmittance is improved by changing the shape of an electrode.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for mobile image display device because of its excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a television and a computer monitor for receiving and displaying broadcast signals.

In order to use such a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. Can be.

A general liquid crystal display device may be largely divided into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel, wherein the liquid crystal panel includes first and second glass substrates bonded to each other with a predetermined space; It consists of a liquid crystal layer injected between the said 1st, 2nd glass substrate.

The first glass substrate (TFT array substrate) may include a plurality of gate wires arranged in one direction at a predetermined interval, a plurality of data wires arranged at regular intervals in a direction perpendicular to the respective gate wires, A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing gate lines and data lines, and a plurality of thin film transistors switched by signals of the gate lines to transfer signals of the data lines to each pixel electrode. Is formed.

The second glass substrate (color filter substrate) includes a light shielding layer for blocking light in portions other than the pixel region, an R, G, and B color filter layers for expressing color colors, and a common electrode for implementing an image. Is formed.

The driving principle of the general liquid crystal display device uses the optical anisotropy and polarization property of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the arrangement of molecules can be controlled by artificially applying an electric field to the liquid crystal.

Therefore, when the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal by optical anisotropy, thereby representing image information.

Currently, an active matrix LCD, in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner, is attracting the most attention due to its excellent resolution and ability to implement video.

Hereinafter, a liquid crystal display according to the related art will be described with reference to the accompanying drawings.

1 is an exploded perspective view illustrating a liquid crystal display of a typical twisted nematic (TN) mode.

As shown in FIG. 1, the lower plate 1 and the upper plate 2 bonded to each other with a predetermined space and a liquid crystal 3 injected between the lower plate 1 and the upper plate 2 are constituted.

More specifically, the lower plate 1 has a plurality of gate lines 4 arranged in one direction at regular intervals to define the pixel region P, and is fixed in a direction perpendicular to the gate line 4. A plurality of data lines 5 are arranged at intervals, and a pixel electrode 6 is formed in each pixel region P where the gate line 4 and the data line 5 intersect, and each gate line ( The thin film transistor T is formed at a portion where the 4) and the data line 5 cross each other.

The upper plate 2 implements an image with a light shielding layer 7 for blocking light in portions other than the pixel region P, an R, G, and B color filter layer 8 for expressing color colors, and an image. The common electrode 9 for this is formed.

The thin film transistor T may include a gate electrode protruding from the gate line 4, a gate insulating film (not shown) formed on a front surface, an active layer formed on the gate insulating film above the gate electrode, and the data. And a source electrode protruding from the line 5 and a drain electrode to face the source electrode.

The pixel electrode 6 uses a transparent conductive metal having a relatively high transmittance of light, such as indium tin oxide (ITO).

As described above, in the liquid crystal display device configured, the liquid crystal 3 positioned on the pixel electrode 6 is aligned by a signal applied from the thin film transistor T, and the liquid crystal 3 is aligned according to the degree of alignment of the liquid crystal 3. An image can be expressed by controlling the amount of light passing through the liquid crystal 3.

As described above, the liquid crystal panel drives the liquid crystal by an electric field applied up and down, and has excellent characteristics such as transmittance and aperture ratio, and the common electrode 9 of the upper plate 2 serves as a ground so that The destruction of the liquid crystal cell can be prevented.

However, the liquid crystal drive by the electric field applied up-down has a disadvantage that the viewing angle characteristics are not excellent.

Accordingly, in order to overcome the above disadvantages, a new technology, that is, a liquid crystal display device having an In-Plane Switching Mode (IPS) mode and a Vertical Alignment (VA) mode, has been proposed.

FIG. 2 is a plan view illustrating a liquid crystal display of a general IPS mode, and FIG. 3 is a cross-sectional view taken along line II ′ of FIG. 2.

As shown in FIGS. 2 and 3, the liquid crystal display of the general IPS mode includes a lower panel 10, an upper panel 20 opposite to the upper panel 20, and a liquid crystal 25 filled between the two substrates 10 and 20. have.

A gate line 11 and a data line 12 are formed on the lower plate 10 to cross each other in the vertical and horizontal directions, and the common electrode 13 and the pixel electrode 15 are spaced apart from each other by a predetermined interval. It is formed.

The gate electrode 11a protruding from the gate line 11 and the gate electrode 11a are overlapped with the gate insulating layer 14 on the entire surface of the lower plate 10 including the gate electrode 11a. The thin film transistor TFT includes a semiconductor layer 18, a source electrode 12a protruding from the data line 12 on both sides of the semiconductor layer 18, and a drain electrode 12b spaced apart from the predetermined distance. Is formed. The drain electrode 12b of the thin film transistor TFT is connected to the pixel electrode 15.

The common electrode 13 is formed to be spaced apart from the pixel electrode 15 by a predetermined interval, and is simultaneously formed on the same layer as the gate line 11 or the data line 12. In the drawing shown, the common electrode 13 is formed on the same layer as the gate line 11.

Further, an insulating film 16 is further deposited between the data line 12 and the pixel electrode 15, wherein the insulating film 16 is formed of an inorganic material such as SiNx, SiOx, or the like as the gate insulating film 14. Any one of an insulating film, an organic insulating film of acryl, polyimide, BCB (BenzoCycloButene), or photo polymer is used.

In addition, the passivation layer 17 and the first alignment layer 18 are sequentially formed on the entire lower plate 10 including the insulating layer 16 and the pixel electrode 15.

The common electrode 13 is electrically connected to the common line 19 to receive a voltage signal. When the voltage signal is applied to each pixel electrode 15 through the drain electrode 12b, the common electrode 13 forms a transverse electric field. 25).

On the top plate 20, a light shielding layer 21 for blocking light leakage to areas other than the pixel region, a color filter layer 22 for implementing color hues (R, G, B), and the color The overcoat layer 23 for planarizing each color film of the filter layer 22 and the second alignment film 24 for defining the initial orientation of the liquid crystal are formed.

The first and second alignment layers 18 and 24 are subjected to rubbing at a pretilt angle of 2 to 5 ° so that the initial alignment of the liquid crystals is aligned in the direction horizontal to the surfaces of both substrates 10 and 20.

The illustrated figure follows the optical mode of the general IPS mode, and does not transmit light before voltage is applied to normally black.

When a voltage is applied to the pixel electrode 15 and the common electrode 13, an electric field is formed between two electrodes 13 and 15 formed on the same substrate, and an electric field formed between the two electrodes 13 and 15 is formed. The liquid crystal 25 is thus aligned.

After voltage is applied, internal light is transmitted along the liquid crystal 25 to display a white state.

Here, since the liquid crystal 25 corresponding to the portion where the pixel electrode 15 and the common electrode 13 are formed is located in an area where electric fields are divided, it is not easy to move in a specific direction when voltage is applied to each electrode. . Therefore, when the display is performed, the pixel becomes a portion where foreground lines are formed, and light is not transmitted through the pixel electrode 15 and the formation region of the common electrode 13 so that the pixel electrode 15 and the common electrode ( 13) is formed of metal or deposited by alloy of ITO / metal to prevent light leakage phenomenon.

In this manner, the common electrode 13 and the pixel electrode 15 are formed on the same plane on the lower plate 10. The liquid crystal 25 formed between the lower plate 10 and the upper plate 20 bonded to the lower plate 10 is driven by an electric field between the common electrode 13 and the pixel electrode 15 on the lower plate 10. . At this time, the liquid crystal 25 is positive in dielectric anisotropy, and has a characteristic in which the major axis is oriented in the direction of the electric field.

In the off state in which the transverse electric field is not applied to the common electrode 13 or the pixel electrode 15, the orientation direction change of the liquid crystal 3 does not occur. On the other hand, in the on state in which the transverse electric field is applied to the common electrode 13 and the pixel electrode 15, the alignment direction change of the liquid crystal 25 occurs, and the distortion angle is about 45 ° compared to the off state. And the liquid crystal is aligned.

4 is a plan view illustrating a liquid crystal display device of a general MVA mode, and FIG. 5 is a cross-sectional view taken along line II-II ′ of FIG. 4.

4 and 5, in the liquid crystal display of the general MVA mode, a gate line 31 and a data line 32 are formed on the lower plate 30 to cross each other in a vertical direction to define a pixel area, and within the pixel area. The pixel electrode 35 having one or more slits spaced apart from each other by a predetermined interval is formed. The gate electrode 11a protruding from the gate line 11 and the gate electrode 11a are overlapped with the gate insulating layer 14 on the entire surface of the lower plate 10 including the gate electrode 11a. The thin film transistor TFT includes a semiconductor layer 18, a source electrode 12a protruding from the data line 12 on both sides of the semiconductor layer 18, and a drain electrode 12b spaced apart from the predetermined distance. Is formed. The drain electrode 12b of the thin film transistor TFT is connected to one side of the pixel electrode 15.

The upper plate 40 includes a black matrix (not shown) corresponding to a portion other than the pixel region, an R, G, and B color filter layer 41 corresponding to the pixel region portion, and the color filter layer 41. The front plate 40 includes a protrusion-like dielectric material 43 formed between the common electrode 42 and the slit of the pixel electrode 35.

In the liquid crystal display of the general MVA mode, an alignment film (not shown) subjected to vertical rubbing is coated on the upper and lower plates 40 and 30, and a liquid crystal having a negative dielectric anisotropy is used.

Accordingly, the liquid crystal display of the general MVA mode is vertically aligned in an initial state where no voltage is applied. However, when the voltage is applied, the common electrode 42 and the pixel electrode of the upper and lower plates 40 and 30 are applied as shown in FIG. 5. Since a vertical electric field is formed between 35 and the liquid crystal 45 is oriented in a direction perpendicular to the electric field, the liquid crystal has an orientation inclined obliquely close to the horizontal plane.

In this case, the slit of the pixel electrode 35 and the dielectric material 43 are structures that distort the electric field so that the alignment position of the liquid crystal may be different in a desired portion by adjusting the formation position and direction. The slit and the dielectric material serve as a boundary between domains in which the alignment direction of the liquid crystal is different.

However, the liquid crystal display of the conventional IPS mode and VA mode as described above has the following problems.

The liquid crystal display of the IPS mode has a rectangular shape in which the shape of the vertical cross section of the pixel electrode and the common electrode of the lower plate is equal to the length of the upper and lower surfaces thereof, and the portion of the pixel electrode and the common electrode occupies on the substrate. In this case, a radial electric field forming portion, which is neither a vertical electric field nor a transverse electric field, appears around the pixel electrode or the common electrode, so that the liquid crystals arranged along this area are inclined, whereby a problem of lowering transmittance appears.

Similarly, the VA mode liquid crystal display device applies a vertical electric field to the pixel electrode on the lower plate and the common electrode on the upper plate, and forms a horizontal alignment using the liquid crystal having a negative dielectric anisotropy. A vertical electric field is not formed, but a fringe electric field is formed. Similarly to the above-described liquid crystal display device of the IPS mode, the transmittance is reduced at this site.

As described above, in the liquid crystal display of the IPS mode or the VA mode, the viewing angle improvement is achieved by forming a horizontal electric field or forming a plurality of domains, but the liquid crystals around the patterned electrode or around the slit and the dielectric material are not lie down completely and are oriented at an angle. It is desired to solve the problem in which this phenomenon occurs and the transmittance is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a liquid crystal display device having improved transmittance by changing the shape of an electrode.

In order to achieve the above object, a liquid crystal display of the present invention includes a first and second substrates facing each other, a plurality of gate lines and data lines vertically intersecting on the first substrate, and defining pixel regions; A plurality of first common electrodes formed in the pixel region, a plurality of pixel electrodes alternated with the first common electrodes, a second common electrode formed on an entire surface of the second substrate, and the first and second substrates. It is characterized by including a liquid crystal layer formed between the first and second alignment layers and the first and second alignment layers that are vertically aligned.

A dielectric layer is further included between the second common electrode and the second alignment layer.

The liquid crystal layer is composed of liquid crystal molecules having a positive dielectric anisotropy.

The same voltage is applied to the first common electrode and the second common electrode.

The first common electrode and the pixel electrode are metal.

The first common electrode and the pixel electrode are formed on the same layer as the gate line or the data line.

The second common electrode is a transparent electrode.

The second substrate further includes a black matrix layer corresponding to a portion other than the pixel region and a color filter layer corresponding to the pixel region.

In addition, the liquid crystal display device of the present invention for achieving the same object, the first and second substrates facing each other, a plurality of gate lines and data lines that vertically intersect on the first substrate to define a pixel region, A plurality of first common electrodes formed in the pixel region, a plurality of pixel electrodes alternately with the first common electrodes, the upper surface of the vertical cross section of which is smaller than the lower surface, and a second formed on the entire surface of the second substrate; Another characteristic is that the liquid crystal layer is formed between the common electrode and the first and second substrates.

Further comprising a dielectric layer on the second common electrode.

The pixel electrode has a trapezoidal vertical cross section.

The pixel electrode has a triangular vertical cross section.

The pixel electrode has a semicircular vertical section.

The semiconductor device may further include first and second alignment layers vertically oriented on the first and second substrates.

The liquid crystal layer is composed of liquid crystal molecules having a positive dielectric anisotropy.

The same voltage is applied to the first common electrode and the second common electrode.

The first common electrode has the same shape as the pixel electrode.

The first common electrode and the pixel electrode are metal.

The first common electrode and the pixel electrode are formed on the same layer as the gate line or the data line.

The second common electrode is a transparent electrode.

The second substrate further includes a black matrix layer corresponding to a portion other than the pixel region and a color filter layer corresponding to the pixel region.

Hereinafter, the liquid crystal display of the present invention will be described in detail with reference to the accompanying drawings.

The liquid crystal display according to the present invention described in the following embodiments is almost similar to the liquid crystal display of the general IPS mode. However, by forming the vertical alignment layer vertically aligned on the lower plate and the upper plate facing each other, the liquid crystal is vertically aligned in the initial state without a voltage applied. This mode is called VA-IPS mode.

6 is a plan view illustrating a liquid crystal display according to a first exemplary embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along line III-III ′ of FIG. 6.

6 and 7, the liquid crystal display according to the first exemplary embodiment of the present invention has a gate line 81 and a data line 82 intersecting vertically and horizontally on the lower plate 80 to define a pixel area. The pixel electrode 84 and the first common electrode 85 are formed to be parallel to each other at a predetermined interval in the pixel area.

The gate electrode 81a protrudes from the gate line 81 and overlaps with the gate electrode 81a through a gate insulating film 79 on the entire surface of the lower plate 80 including the gate electrode 81a. The thin film transistor TFT includes a semiconductor layer 88, a source electrode 82a protruding from the data line 82 on both sides of the semiconductor layer 88, and a drain electrode 82b spaced apart from the predetermined distance. Is formed. The drain electrode 82b of the thin film transistor TFT is connected to the pixel electrode 84.

The first common electrode 85 is formed to be spaced apart from the pixel electrode 84 by a predetermined interval, and is electrically connected to a common line 85a to which a common voltage is applied. Although not shown in the drawing, the first common electrode 85 and the common line 85a are formed on the same layer to improve the degree of integration.

The pixel electrode 84 is formed on the same layer as the data line 82 and the source / drain electrodes 82a and 82b.

Subsequently, an insulating film 83 is further deposited on the entire surface including the data line 82 and the pixel electrode 84, wherein the insulating film 83 is formed of the same composition as the gate insulating film 79, and may be formed of inorganic materials such as SiNx, SiOx, or the like. Any one of an insulating film, an organic insulating film of acryl, polyimide, BCB (BenzoCycloButene), or photo polymer is used.

In addition, the passivation layer 86 and the first alignment layer 87 are sequentially formed on the entire surface of the insulating layer 83 including the data line 82 and the pixel electrode 84.

On the upper plate 90, a light shielding layer 91 for blocking light leakage to areas other than the pixel region, a color filter layer 92 for implementing color hues (R, G, B), and a front surface The second common electrode 93 formed, the dielectric layer 94 formed on the second common electrode 93, and the second alignment layer 95 for defining initial alignment of the liquid crystal are formed.

Here, the first and second alignment layers 87 and 95 defining the initial alignment of the liquid crystal 99 on the lower and upper plates 80 and 90 are subjected to vertical rubbing, and thus the initial alignment of the liquid crystal 99. Is oriented perpendicular to the lower and upper plates 80, 90.

In the initial state, the same voltage is applied to the first and second common electrodes 85 and 93.

In the VA-IPS mode such as the liquid crystal display of the present invention, no light is transmitted through voltage before being normally black.

Then, a voltage different from the first and second common electrodes 85 and 93 is applied to the pixel electrode 84 while the same voltage is applied to the first and second common electrodes 85 and 93. In this case, a transverse electric field is formed between the first common electrode 85 and the pixel electrode 84 formed on the lower plate 80, which is the same substrate, and the second common electrode 93 and the pixel electrode formed on different substrates, respectively. Between 84, a vertical electric field is formed. After the voltage is applied, internal light is transmitted along the liquid crystal 99 to display a white state.

In the liquid crystal display according to the first exemplary embodiment of the present invention shown in FIGS. 6 and 7, the liquid crystal 50 has a positive dielectric anisotropy when the voltage is applied, and thus the pixel electrode 84 is applied when the voltage is applied. The liquid crystal is oriented parallel to the transverse electric field formed between the first common electrodes 93.

Therefore, the liquid crystal display of the present invention has an advantage of being able to be driven at a lower voltage because it is driven by a transverse electric field than the MVA mode which is basically driven by a vertical electric field.

In FIG. 7, the problem of driving voltage is solved by further forming the dielectric layer 94 on the second common electrode. However, even in this case, the problem that the transmittance decreases due to the inclination of the liquid crystal at the boundary of the pixel electrode 84 still remains. have.

That is, in the vertical cross-section as shown in FIG. 7, in the case of the pixel electrode 84 having a rectangular shape in which the upper and lower sides thereof coincide with each other, the liquid crystal molecules positioned at the boundary B of the pixel electrode 84 are inclined. The effect is that the transmittance is reduced in the region adjacent to the pixel electrode 84 as compared with the region adjacent to the common electrode 85.

Here, the vertically aligned portion of the liquid crystal is C, which is the upper portion of the pixel electrode 4, and the boundary portion of the pixel electrode 84, which is oriented so that the liquid crystal is inclined substantially, is B, and the portion where the liquid crystal is aligned horizontally (here, Assuming that the same voltage is applied to the first and second common electrodes).

8 is a plan view illustrating a liquid crystal display according to a second exemplary embodiment of the present invention.

As shown in FIG. 8, the liquid crystal display according to the second exemplary embodiment of the present invention includes a first substrate (see 100 in FIG. 9) and a second substrate (see 110 in FIG. 9) facing each other, and the first and second electrodes. The liquid crystal 130 is filled between the substrates 100 and 110. Here, by forming the vertically aligned vertical alignment layers 37 and 45 on the top surfaces of the first and second substrates 100 and 110 that face each other, the liquid crystal 130 having positive dielectric anisotropy is not used, whereby no voltage is applied. In the initial state, the liquid crystal is aligned vertically, and when voltage is applied, the liquid crystal 130 is driven by an electric field formed in each portion.

A gate line 101 and a data line 102 are formed on the first substrate 100 so as to cross each other in the vertical and horizontal directions, and define a pixel region. The pixel electrode 104 and the first common electrode 105 are formed in the pixel region. ) Are spaced apart at predetermined intervals and are formed in parallel.

The gate electrode 101a is formed to protrude from the gate line 101 and the gate electrode 101 (see 107 in FIG. 7) is disposed on the entire surface of the lower plate 100 including the gate electrode 101a. A thin film transistor including a semiconductor layer 103 overlapping 101a, a source electrode 102a protruding from the data line 102 on both sides of the semiconductor layer 103, and a drain electrode 102b spaced apart from the predetermined distance. (TFT) is formed. The drain electrode 102b of the thin film transistor TFT is electrically connected to the pixel electrode 104.

The first common electrode 105 is formed to be spaced apart from the pixel electrode 104 by a predetermined interval, and is electrically connected to a common line 106 applying a common voltage. Although not shown in the drawing, the first common electrode 105 and the common line 106 are formed on the same layer to improve the degree of integration.

The pixel electrode 104 may be formed on the same layer as the data line 32 and the source / drain electrodes 32a and 32b or may be formed of a metal material having light blocking properties such as chromium (Cr) and titanium (Ti). . Therefore, light leakage does not occur in the portion where the pixel electrode is positioned regardless of the vertical alignment of the liquid crystal 130. In addition, the pixel electrode 104 is formed in a shape in which the top surface a has a length smaller than the bottom surface b when viewed in a vertical section.

9 to 14 are cross-sectional views illustrating various types of electrodes on a line IV to IV 'according to a second embodiment of the present invention.

As shown in FIG. 9, in the liquid crystal display according to the exemplary embodiment of the present invention, the vertical cross section of the pixel electrode 104 is trapezoidal.

Therefore, only the liquid crystal 130 that is oriented in a portion having a step when the voltage is applied has an oblique alignment, and the liquid crystal 130 that is oriented in a portion other than the pixel electrode 104 has a horizontal alignment. Have it.

The liquid crystal display according to the first embodiment will be described in more detail.

The liquid crystal display according to the first exemplary embodiment includes liquid crystals 130 filled between the first and second substrates 110 and 110, which face each other, and the first and second substrates 100 and 110, which face each other. Is done.

On the first substrate 100, a gate line 101 protruding from the gate electrode 101a is formed corresponding to each pixel area.

A gate insulating layer 107 is formed on the entire surface of the first substrate 100 including the gate line 101.

A source electrode 102a protruding from the data line 102 perpendicularly to the gate line 101 on the gate insulating layer 107, protruding from the data line 102, and formed in each pixel region, and the source electrode ( A pixel electrode 104 having a plurality of branched patterns in a direction parallel to the data line 102 is formed integrally with the drain electrode 102b and the drain electrode 102b electrode spaced apart from the region 102. Here, the pixel electrode 104 has a trapezoidal shape in which the upper surface a is shorter than the lower surface b when viewed in a vertical section.

Although the pixel electrode 104 is shown on the same layer as the data line 102 in the drawing, as described above, the pixel electrode 104 may be formed on a different layer from the data line 102 to facilitate formation of a trapezoidal pattern. 104 may also be formed.

An insulating film 108 is formed on the entire gate insulating film 107 including the data line 102 and the pixel electrode 104.

The first common electrode 105 is formed on the insulating layer 108 at a position alternated with the pixel electrode 104 in a direction parallel to the pixel electrode 104. A common line 106 for applying a voltage to the common electrode 105 is formed on the same layer as the first common electrode 105.

The passivation layer 109 and the first alignment layer 121 are sequentially formed on the entire surface of the insulating layer 108 including the first common electrode 105.

The gate insulating film 107, the insulating film 108, and the protective film 109 may be formed of an inorganic insulating film, such as SiNx or SiOx, or an organic insulating film of acryl, polyimide, BenzocycloButene (BCB), or photopolymer. Use

On the second substrate 110, a black matrix (not shown) for blocking light leakage to an area other than the pixel area, a color filter layer 112 for implementing color hue (R, G, B) and The second common electrode 113 formed on the front surface of the color filter layer 112, the dielectric layer 114 formed on the entire surface of the second common electrode 113, and the second alignment layer 122 for defining the initial alignment of the liquid crystal are formed. Is formed.

The first and second alignment layers 121 and 122 are vertically rubbed to allow the liquid crystal 130 to be oriented perpendicular to the surfaces of the first and second substrates 100 and 110 in the initial state.

Here, an overcoat layer may be further formed on the color filter layer 112 for planarization.

In the initial state, the same voltage is applied to the first and second common electrodes 105 and 113.

The liquid crystal display of the present invention is normally black and does not transmit light in an initial state.

When a voltage different from the first and second common electrodes 105 and 113 is applied to the pixel electrode 104 while the same voltage is applied to the first and second common electrodes 105 and 113. A transverse electric field is formed between the first common electrode 105 and the pixel electrode 104 formed on the first substrate 100, which is the same substrate, and the second common electrode 113 formed on the different substrates 100 and 110, respectively. ) And the pixel electrode 104, a vertical electric field is formed. Therefore, after voltage is applied, internal light is transmitted along the liquid crystal 130 to display a white state.

When the voltage is applied as described above, since the pixel electrode 104 has a trapezoidal shape in which the upper side is smaller than the lower side when viewed in the vertical section as shown in FIG. Since the step B of the upper and lower sides occurs only, the light leakage phenomenon is reduced and the transmittance is improved as compared with the conventional rectangular pixel electrode.

Here, the portion where the liquid crystal 130 is vertically aligned is C, which is the upper portion of the pixel electrode 104, and the boundary portion of the pixel electrode 104, which is substantially oriented so that the liquid crystal is inclined, is B, and the liquid crystal is horizontally aligned. The region (assuming that the same voltage is applied to the first and second common electrodes) is denoted by A.

In this case, the transmittance around the pixel electrode 104 and its surroundings is at a level similar to that of the first common electrode 105 and its surroundings.

As shown in FIG. 10, the liquid crystal display according to another exemplary embodiment of the present invention has a triangular shape when the pixel electrode 134 is viewed in a vertical cross section.

Therefore, when the voltage is applied, the electric field distortion around the pixel electrode 134 is minimized by the vertical electric field formed by the second common electrode 113 and the dielectric layer 114 on the second substrate 110 and the first common. Only the liquid crystal 130 positioned on the upper surface where the electrode 105 is positioned has a tilted shape, thereby maintaining the director of the liquid crystal 130 in a portion other than the pixel electrode 134 in the horizontal direction, thereby improving transmittance. Can be.

In this case, the transmittance of the pixel electrode 134 and the surroundings thereof is at or above a level similar to or higher than that of the first common electrode 105 and the surroundings thereof.

Here, it is assumed that the voltages applied to the first and second common electrodes 105 and 113 are the same voltage.

As shown in FIG. 11, another embodiment of the liquid crystal display according to the second exemplary embodiment has a semicircular shape when the pixel electrode 144 is viewed in a vertical cross section.

Accordingly, when the voltage is applied, the electric field distortion around the pixel electrode 144 is minimized by the vertical electric field formed by the second common electrode 113 and the dielectric layer 114 on the second substrate 110 and the first common. Only the liquid crystal 130 positioned on the upper surface where the electrode 105 is positioned has a tilted shape, thereby maintaining the director of the liquid crystal 130 in a portion other than the pixel electrode 144 in the horizontal direction, thereby improving transmittance. Can be.

In this case, the transmittance of the pixel electrode 144 and the surroundings thereof may be at a level similar to that of the first common electrode 105 and the surroundings of the pixel electrode 144, and the director of the liquid crystal may be more continuously modified.

Here, it is assumed that the voltages applied to the first and second common electrodes 105 and 113 are the same voltage.

As shown in FIG. 12, the liquid crystal display according to the second exemplary embodiment of the present invention has the same shape as that of the first common electrode 135 and the pixel electrode 104 of FIG. 9. Short and underside has long trapezoid.

Therefore, when the voltage is applied, the electric field distortion around the first common electrode 135 due to the vertical electric field formed by the second common electrode 113 and the dielectric layer 114 on the second substrate 110 is minimized and the first 1 so that only the liquid crystal 130 positioned on the upper surface where the common electrode 135 is positioned has an inclined shape, thereby maintaining the director of the liquid crystal 130 in a portion other than the pixel electrode 104 in the horizontal direction, thereby improving transmittance. Can be improved.

In this case, the same voltage may be applied to the first and second common electrodes 135 and 113 and a different voltage may be applied to the pixel electrode 104 as shown in FIG. ), A vertical electric field may be formed between the first and second common electrodes 135 and 113 by applying a voltage to the second common electrode 113 to the same degree. In this case, the alignment of the liquid crystal 130 around the first common electrode 135 is equal to the upper and lower steps of the first common electrode 135 in the same manner as the alignment of the liquid crystal 130 around the pixel electrode 104. Only the area where the liquid crystal is tilted appears.

As shown in FIG. 13, in another liquid crystal display according to the second exemplary embodiment, the first common electrode 145 has the same shape as that of the second embodiment and the pixel electrode 134, and the vertical cross section is triangular. It has a phosphorus shape.

Therefore, when the voltage is applied, the electric field distortion around the first common electrode 135 due to the vertical electric field formed by the second common electrode 113 and the dielectric layer 114 on the second substrate 110 is minimized and the first 1 Only the liquid crystal 130 positioned on the upper surface where the common electrode 145 is positioned to have an inclined shape, thereby maintaining the director of the liquid crystal 130 in a portion other than the pixel electrode 134 in a horizontal direction, thereby improving transmittance. Can be improved.

Like the above-described embodiments, the same voltage may be applied to the first and second common electrodes 145 and 113 and a different voltage may be applied to the pixel electrode 134 when the voltage is applied. A voltage may be applied to the second common electrode 113 to the same degree as 134 to form a vertical electric field between the first and second common electrodes 145 and 113. In this case, the alignment of the liquid crystal 130 around the first common electrode 145 is the same as that of the liquid crystal 130 around the pixel electrode 134. An inclined region 130 appears.

As shown in FIG. 14, in another liquid crystal display according to the second embodiment of the present invention, the first common electrode 135 has the same shape as that of the first embodiment and the pixel electrode 104, and has a semi-circular cross-sectional shape. It has a shape that is a mold.

Therefore, when the voltage is applied, the electric field distortion around the first common electrode 155 around the first common electrode 155 due to the vertical electric field formed by the second common electrode 113 and the dielectric layer 114 on the second substrate 110 is minimized. 1 Only the liquid crystal 130 located on the upper surface where the common electrode 155 is positioned to have an inclined shape, thereby maintaining the director of the liquid crystal 130 in a portion other than the pixel electrode 144 in the horizontal direction, thereby improving transmittance. Can be improved.

As in the above-described embodiment, when the voltage is applied, the same voltage may be applied to the first and second common electrodes 155 and 113, and a different voltage may be applied to the pixel electrode 144. A voltage may be applied to the second common electrode 113 to the same degree as that of 144 to form a vertical electric field between the first and second common electrodes 155 and 113. In this case, the alignment of the liquid crystal 130 around the first common electrode 155 is the same as that of the liquid crystal 130 around the pixel electrode 144. From then on, the alignment of the liquid crystals having a continuous inclined shape is achieved.

10 to 14 have the same configuration as the liquid crystal display according to the second exemplary embodiment shown in FIG. 9 except for the pixel electrode or the common electrode, and thus, parts except for the pixel electrode and the common electrode may be denoted by the same reference numeral. Specified.

The liquid crystal display of the present invention as described above has the following effects.

First, by adopting the VA-IPS structure in which the pixel electrode and the common electrodes are formed in the initial vertical alignment and one side substrate, the electric field is smoothly formed even at a lower driving voltage in the simple MAVA mode, thereby improving the response speed of the liquid crystal alignment.

Second, the shape of the pixel electrode is trapezoidal, triangular or semi-circular to form the lower side longer than the upper side, so that the light inclined to the upper portion of the electrode when the voltage is applied to prevent the light leakage, thereby improving the transmittance.

1 is an exploded perspective view showing a liquid crystal display of a general TN mode;

2 is a plan view illustrating a liquid crystal display device in a general IPS mode.

3 is a cross-sectional view taken along line II ′ of FIG. 2.

4 is a plan view illustrating a liquid crystal display of a general MVA mode.

5 is a cross-sectional view taken along line II-II ′ of FIG. 4.

6 is a plan view illustrating a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along line III-III ′ of FIG. 6.

8 is a plan view illustrating a liquid crystal display according to a second exemplary embodiment of the present invention.

9 to 14 are cross-sectional views illustrating various types of electrodes on a line IV to IV 'according to a second embodiment of the present invention.

* Description of symbols on the main parts of the drawings *

80, 100: first substrate 81, 101: gate line

81, 101a: gate electrode 82, 102: data line

82a / 82b: source electrode / drain electrode 88, 103: semiconductor layer

102a / 102b: source electrode / drain electrode 84, 104: pixel electrode

85 and 105: first common electrode 85a and 106: common line

107: gate insulating film 83: insulating film

86, 109: protective film 90, 110: second substrate

91: black matrix layer 92, 112: color filter layer

93 and 113: second common electrode 94 and 114: dielectric layer

87, 121: first alignment layer 95, 122: second alignment layer

99, 130: liquid crystal 134, 144: pixel electrode

135, 145, and 155: first common electrode

Claims (21)

First and second substrates facing each other; A plurality of gate lines and data lines vertically intersecting on the first substrate to define pixel regions; A plurality of first common electrodes formed in the pixel area; A plurality of pixel electrodes alternate with the first common electrodes; A second common electrode formed on an entire surface of the second substrate; First and second alignment layers vertically oriented on the first and second substrates; And a liquid crystal layer formed between the first and second substrates. The method of claim 1, And a dielectric layer between the second common electrode and the second alignment layer. The method of claim 1, And the liquid crystal layer is made of liquid crystal molecules having a positive dielectric anisotropy. The method of claim 1, And the same voltage is applied to the first common electrode and the second common electrode. The method of claim 1, And the first common electrode and the pixel electrode are metal. The method of claim 1, The first common electrode and the pixel electrode are formed on the same layer as the gate line or the data line. The method of claim 1, And the second common electrode is a transparent electrode. The method of claim 1, And a black matrix layer corresponding to a portion other than the pixel region and a color filter layer corresponding to the pixel region on the second substrate. First and second substrates facing each other; A plurality of gate lines and data lines vertically intersecting on the first substrate to define pixel regions; A plurality of first common electrodes formed in the pixel area; A plurality of pixel electrodes which are alternated with the first common electrodes and whose upper surface of the vertical cross section is smaller than the lower surface; A second common electrode formed on an entire surface of the second substrate; And a liquid crystal layer formed between the first and second substrates. The method of claim 9, And a dielectric layer on the second common electrode. The method of claim 9 And the pixel electrode has a trapezoidal vertical cross section. The method of claim 9, And the pixel electrode has a vertical cross section of the pixel electrode. The method of claim 9, And the pixel electrode has a semicircular vertical section. The method of claim 9, And first and second alignment layers vertically oriented on the first and second substrates. The method of claim 9, And the liquid crystal layer is made of liquid crystal molecules having a positive dielectric anisotropy. The method of claim 9, And the same voltage is applied to the first common electrode and the second common electrode. The method of claim 9, The first common electrode has the same shape as the pixel electrode. The method of claim 9, And the first common electrode and the pixel electrode are metal. The method of claim 9, The first common electrode and the pixel electrode are formed on the same layer as the gate line or the data line. The method of claim 9, And the second common electrode is a transparent electrode. The method of claim 9, And a black matrix layer corresponding to a portion other than the pixel region and a color filter layer corresponding to the pixel region on the second substrate.