KR20120076936A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to gradually bend an end of an upper electrode according to the profile of a pixel, thereby preventing disclination. CONSTITUTION: A gate line crosses a data line. A pixel area is defined by the gate line and the data line. A thin film transistor is formed on the pixel area. A lower electrode(130) supplies a data voltage to a light transmitting area. An upper electrode(140) is overlapped with the lower electrode. A passivation layer is placed between the upper and lower electrodes.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and in particular, an edge of an upper transparent electrode (ITO) is bent at a predetermined angle along a profile of a pixel to prevent foreground phenomenon and improve a fringe field (Fringe Field). The present invention relates to a mode liquid crystal display device.

With the development of various portable electronic devices such as mobile communication terminals and notebook computers, there is an increasing demand for a flat panel display device that can be applied thereto.

The flat panel display includes a liquid crystal display device, a plasma display panel, a field emission display device, a light emitting diode display device, and an organic light emitting device. (Organic Light Emitting Device) is being studied.

Among such flat panel display devices, the liquid crystal display device has been expanding its application field due to the development of mass production technology, ease of driving means, low power consumption, high definition, and large screen.

Liquid crystal displays have been developed in various ways, such as twisted nematic (TN) mode, vertical alignment (VA) mode, in plane switching (IPS) mode, and fringe field switching (FFS) mode.

In the IPS mode and the FFS mode, a pixel electrode and a common electrode are disposed on a lower substrate to adjust the arrangement of the liquid crystal layer by an electric field between the pixel electrode and the common electrode. In particular, in the IPS mode, the pixel electrode and the common electrode are alternately arranged in parallel so that a horizontal electric field is generated between both electrodes to adjust the alignment of the liquid crystal layer. Such an IPS mode has a disadvantage in that the arrangement of the liquid crystal layer is not controlled in the upper portion of the pixel electrode and the common electrode, thereby decreasing light transmittance in the region.

The FFS mode is designed to solve the shortcomings of the IPS mode. In the FFS mode, the pixel electrode and the common electrode are formed to be spaced apart from each other with an insulating layer interposed therebetween. In this case, one electrode is configured in a plate shape or a pattern and the other electrode is configured in a finger shape to adjust the arrangement of the liquid crystal layer through a fringe field generated between the two electrodes. That's the way.

FIG. 1 is a diagram illustrating one pixel of a plurality of pixels of a fringe field mode liquid crystal display according to the related art.

Referring to FIG. 1, a fringe field mode liquid crystal display according to the related art includes a lower electrode 30 having a protective layer (not shown) interposed in a transmission region through which light from a backlight unit is transmitted. ) And the upper electrode 40. The lower electrode 30 and the upper electrode 40 are formed of indium tin oxide (ITO) so that light supplied from the backlight unit can be transmitted.

The lower electrode 30 is connected to the drain 30 of the TFT (thin film transistor) formed in the channel region to supply the data voltage supplied from the data driver D-IC (not shown) to the pixel.

The upper electrode 40 is patterned into a finger shape to form a plurality of electrode patterns, and is formed on the lower electrode 30 with a protective layer (not shown, an insulating layer) interposed therebetween. The upper electrode 40 supplies a common voltage Vcom to the pixel.

An electric field is formed in each pixel by the data voltage applied to the lower electrode 30 and the common voltage applied to the upper electrode 40, and the liquid crystal behaves according to the formed electric field, thereby adjusting the light transmittance of each pixel.

In the fringe field mode liquid crystal display according to the related art including the above-described configuration, the upper electrode 40 is formed so as to overlap the lower electrode 30. The upper electrode is formed along the structure of the pixel to increase light transmittance. The length of the electrode pattern 40 is extended.

At this time, an electric field is abnormally formed at the end portion ('A' portion of FIG. 1) of the upper electrode 40 along the structure of the pixel so that the liquid crystal loses its orientation. As a result, as shown in FIG. 2, a discrepancy shape is generated in the middle portion of the pixel, thereby degrading display quality.

Recently, a touch screen that allows a user to directly input information on a screen by using a finger or a pen has been applied to replace a conventional input device such as a mouse or a keyboard as an input device of a flat panel display.

When the touch screen is applied to a fringe field mode liquid crystal display according to the related art, an end portion of which the length of the upper electrode 40 is extended by the pressure applied according to the user's touch ('A' in FIG. 1). Portion of the liquid crystal loses the direction is more severe. As a result, as shown in FIG. 3, the user's touch traces appear in the form of gray, causing a white mura to occur.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above-described problem, and to provide a liquid crystal display device which can prevent the occurrence of a foreground phenomenon by gradually bending an end of an upper electrode at a predetermined angle according to a profile of a pixel. It is a task.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and according to a profile of a pixel, a liquid crystal display capable of gradually improving the white mura according to a user's touch by bending the end of the upper electrode at a predetermined angle. To provide a technical problem.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

A liquid crystal display according to an exemplary embodiment of the present invention includes a thin film transistor formed in a pixel region defined by gate lines and data lines formed to intersect; A lower electrode formed to be connected to the drain of the thin film transistor to supply a data voltage to the light transmitting region; And an upper electrode patterned with a plurality of pinker electrodes, the upper electrode being formed to overlap the lower electrode with a protective layer therebetween, wherein the upper electrode is gradually extended in length and predetermined at an end along the profile of the pixel. It is characterized by being bent at an angle.

The upper electrode of the liquid crystal display according to the embodiment of the present invention is characterized in that the end portion is formed so that the inner and outer angles are bent at 45 °.

The upper electrode of the liquid crystal display according to the embodiment of the present invention is characterized in that the end portion is formed such that the inner angle is bent at 42 °, the outer angle is bent at 48 °.

The upper electrode of the liquid crystal display according to the embodiment of the present invention is characterized in that the end portion is formed such that the inner angle is bent at 40 °, the outer angle is bent at 50 °.

The upper electrode of the liquid crystal display according to the embodiment of the present invention is characterized in that the end portion is formed so that the inner angle is bent at 44 °, the outer angle is bent at 46 °.

In the liquid crystal display according to the exemplary embodiment of the present invention, a touch screen for detecting a touch of a user may include a touch screen having an add-on, an on-cell, or an in-cell. Characterized in that it is further included as a type.

In the liquid crystal display according to the exemplary embodiment of the present invention, the edge of the upper electrode may be gradually bent at a predetermined angle according to the profile of the pixel to prevent occurrence of a foreground phenomenon.

According to an exemplary embodiment of the present invention, the end portion of the upper electrode may be gradually bent at a predetermined angle according to the profile of the pixel, thereby improving white mura according to the user's touch.

In addition, other features and advantages of the present invention may be newly understood through the embodiments of the present invention.

1 is a diagram illustrating one pixel of a plurality of pixels of a fringe field mode liquid crystal display according to the prior art;
FIG. 2 is a diagram illustrating a disclination phenomenon occurring in a fringe field mode liquid crystal display according to the related art. FIG.
3 is a view showing a white mura generated in a fringe field mode liquid crystal display according to the prior art.
4 is a cross-sectional view schematically illustrating a pixel structure of a liquid crystal display according to an exemplary embodiment of the present invention.
5 is a plan view schematically illustrating a pixel structure of a liquid crystal display according to an exemplary embodiment of the present invention.
FIG. 6 is a diagram illustrating an effect of improving white mura through application of the pixel structure illustrated in FIG. 5. FIG.
7 is a plan view schematically illustrating a pixel structure of a liquid crystal display according to another exemplary embodiment of the present invention.

Hereinafter, a liquid crystal display according to embodiments of the present invention will be described with reference to the accompanying drawings.

Prior to the description with reference to the drawings, the liquid crystal display according to the embodiments of the present invention has a structure of the FFS mode, the touch screen is an add-on (on-cell) or on-cell (in-cell) in-cell) type.

In addition, the liquid crystal display according to the embodiments of the present invention includes a backlight unit and a driving circuit unit for supplying light to the liquid crystal panel.

The driving circuit unit includes a timing controller T-con, a data driver D-IC, a gate driver G-IC, a sensing driver, a backlight driver, and a power supply unit for supplying driving power to the driving circuits.

Here, all or part of the driving circuit unit may be formed on the liquid crystal panel in a chip on glass (COG) or chip on flexible printed circuit (chip on film) method.

The liquid crystal panel includes an upper substrate and a lower substrate bonded to each other with a liquid crystal layer interposed therebetween. The transmittance is adjusted to display an image according to the video signal.

The upper substrate may include a black matrix BM defining a pixel area to correspond to each of the plurality of pixels; Red, green, and blue color filters formed in each pixel area defined by the black matrix; And an overcoat layer formed to cover the red, green, and blue color filters and the black matrix to planarize the upper substrate.

A gate line and a data line are formed on the lower substrate so as to be perpendicular to each other, and a plurality of pixels are defined through the gate line and the data line.

A TFT, which is a switching element, is formed in a channel region of each pixel, and an upper electrode patterned in a pinker shape so as to overlap the lower electrode with a lower electrode electrically connected to the TFT and an insulating layer interposed therebetween. do.

The TFT includes a gate electrode, an active layer (semiconductor layer), an insulating layer, and a data electrode (source / drain electrode), and may have a bottom gate structure in which the gate electrode is positioned below the active layer. The electrode may have a top gate structure in which the electrode is positioned on the active layer.

4 is a cross-sectional view schematically illustrating a pixel structure of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 5 is a plan view schematically illustrating a pixel structure of a liquid crystal display according to an exemplary embodiment of the present invention. 4 and 5 illustrate one pixel among a plurality of pixels formed in the liquid crystal panel. In FIG. 5, the channel region in which the TFT is formed is not shown.

4 and 5, a gate 110 of a metal material is formed on the lower substrate 100, and an insulating layer 112 is formed to cover the gate to insulate the gate. The active layer 114 and the semiconductor layer are formed on the insulating layer 112, and the drain 120 and the source 122 are formed to contact the active layer. The passivation layer 124 (PAS) is formed on the source and the drain. Through this configuration, a TFT which is a switching element is formed in the channel region.

A lower electrode 130 is formed in the light transmitting region, and a passivation layer 124 (PAS) of a channel region is formed on the lower electrode 130 to extend, and is patterned in a finger shape on the passivation layer 124. The upper electrode 140 is formed.

Here, the lower electrode 130 and the upper electrode 140 are formed of indium tin oxide (ITO) so that light supplied from a backlight unit (not shown) can be transmitted.

The lower electrode 130 is connected to the drain 130 of the TFT formed in the channel region, and the data voltage applied to the data line by the data driver D-IC (not shown) is connected to the drain of the TFT. To feed.

The upper electrode 140 is patterned into a finger shape to form a plurality of electrode patterns, and is formed on the lower electrode 130 with a protective layer 124 (insulating layer) interposed therebetween. The upper electrode 140 supplies a common voltage Vcom to the pixel.

An electric field is formed in each pixel by the data voltage applied to the lower electrode 130 and the common voltage applied to the upper electrode 140, and the liquid crystal behaves according to the formed electric field, thereby adjusting the light transmittance of each pixel.

Here, the upper electrode 140 is formed to extend the length of the plurality of finger electrodes so as to overlap the profile of the pixel and the lower electrode 130 to increase the light transmittance.

In addition, the upper electrode 140 is formed by gradually bending at an angle along the profile of the pixel and the lower electrode 130, which are end portions thereof.

Here, the upper electrode 140 may be formed such that both the outer angle θ1 and the inner angle θ2 of the ends are bent at 45 °.

As such, when the ends of the plurality of pinker electrodes are bent at 45 ° along the profile of the pixel to form the upper electrode 140, the lower electrode 130 and the upper electrode 140 may also be formed at the ends of the upper electrode 140. The electric field in accordance with the voltage applied to is normally formed, so that the liquid crystal behaves in the original direction.

Accordingly, the display quality of the liquid crystal display may be improved by preventing the occurrence of a disclination phenomenon caused by the loss of orientation of the liquid crystal in the pixel.

Referring to FIG. 6, when the tip of the upper electrode 140 was bent at 45 ° and the light transmittance was measured, it was confirmed that the light transmittance of 14.8% was obtained. The light transmittance of 14.8% is a level that does not interfere with the image display of the pixel, and does not affect the overall luminance of the liquid crystal panel by preventing the occurrence of foreground phenomenon.

The liquid crystal display according to the embodiment of the present invention is formed by gradually bending the end of the upper electrode 140 to 45 ° according to the profile of the pixel, so that the user at the end of the upper electrode 140 when the touch panel is applied. It is possible to prevent the liquid crystal from losing the directivity due to the touch of.

As a result, the display quality of the liquid crystal display may be improved by improving white mura according to a user's touch.

In another embodiment of the present invention, the light transmittance may be improved by changing the bending angle of the end of the upper electrode 140.

Referring to FIG. 7, a lower electrode 130 of a liquid crystal display according to another exemplary embodiment of the present invention is connected to a drain 130 of a TFT formed in a channel region and connected to a drain of the TFT. The data voltage applied to the data line at D-IC (not shown) is supplied to the pixel.

The upper electrode 140 is patterned into a finger shape to form a plurality of electrode patterns, and is formed on the lower electrode 130 with a protective layer 124 (insulating layer) interposed therebetween. The upper electrode 140 supplies a common voltage Vcom to the pixel.

Here, the upper electrode 140 is formed to extend the length of the plurality of finger electrodes so as to overlap the profile of the pixel and the lower electrode 130 to increase the light transmittance.

In addition, the upper electrode 140 is formed by gradually bending at an angle along the profile of the pixel and the lower electrode 130, which are end portions thereof.

Here, the outer electrode θ3 of the upper electrode 140 may be bent at 42 ° and the inner angle θ4 may be bent at 48 °.

As described above, when the upper electrode 140 is formed such that the outer edges θ3 are bent at 42 ° and the inner angles θ4 are bent at 48 ° along the profile of the pixel, the upper electrodes 140 At the end of the), the electric field is normally formed according to the voltage applied to the lower electrode 130 and the upper electrode 140, thereby causing the liquid crystal to behave in the original direction.

Accordingly, the display quality of the liquid crystal display may be improved by preventing the occurrence of a disclination phenomenon caused by the loss of orientation of the liquid crystal in the pixel.

Referring to FIG. 6, when the outer angle θ3 of the upper electrode 140 was bent at 42 ° and the inner angle θ4 was bent at 48 °, the light transmittance was measured. As a result, the light transmittance of 15.8% was obtained. As a result, the display quality of the liquid crystal display may be improved by improving the light transmittance by 6.8% compared to the above-described embodiment.

In addition, the liquid crystal display according to another exemplary embodiment of the present invention gradually bends the end of the upper electrode 140 at 42 ° and the inner angle θ4 at 48 ° according to the pixel profile. In this case, the liquid crystal is prevented from losing its directivity due to the user's touch at the end of the upper electrode 140 when the touch panel is applied.

As a result, the display quality of the liquid crystal display may be improved by improving white mura according to a user's touch.

Although not shown in the drawings, according to another embodiment of the present invention, the end of the upper electrode 140 is gradually bent at 40 ° and the inside angle θ4 is bent at 50 ° according to the profile of the pixel. You can. In this case, 14.7% light transmittance can be obtained.

Even when the outer edge θ3 is bent at 40 ° and the inner angle θ4 is bent at 50 °, the liquid crystal loses directivity in the pixel as in the above-described embodiments. It is possible to prevent the liquid crystal from losing the directivity due to the user's touch at the end of the upper electrode 140 when preventing the occurrence of the foreground (disclination) that occurred due to the application of the touch panel.

Further, according to another embodiment of the present invention, the end of the upper electrode 140 may be gradually bent at 44 ° and the inner angle θ4 may be bent at 56 ° according to the profile of the pixel. .

Even when the outer edge θ3 is bent at 44 ° and the inner angle θ4 is bent at 46 °, the liquid crystal loses directivity in the pixel as in the above-described embodiments. It is possible to prevent the liquid crystal from losing the directivity due to the user's touch at the end of the upper electrode 140 when preventing the occurrence of the foreground (disclination) that occurred due to the application of the touch panel.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: lower substrate 110: gate
112: insulating layer 114: active
120: drain 122: source
124: passivation layer (PAS) 130: lower electrode
140: upper electrode

Claims (6)

A thin film transistor formed in the pixel region defined by the gate line and the data line formed to cross each other;
A lower electrode formed to be connected to the drain of the thin film transistor to supply a data voltage to the light transmitting region; And
And an upper electrode patterned with a plurality of pinker electrodes to overlap the lower electrode with a protective layer therebetween.
The upper electrode is gradually extended in length, and the end portion is bent at a predetermined angle along the profile of the pixel. The method of claim 1,
The upper electrode is a liquid crystal display, characterized in that the end portion is formed so that the inner and outer angles are bent at 45 °. The method of claim 1,
The upper electrode is a liquid crystal display, characterized in that the end portion is formed such that the inner angle is bent at 42 °, the outer angle is bent at 48 °. The method of claim 1,
The upper electrode is a liquid crystal display, characterized in that the end portion is formed such that the inner angle is bent at 40 °, the outer angle is bent at 50 °. The method of claim 1,
The upper electrode is a liquid crystal display, characterized in that the end portion is formed such that the inner angle is bent at 44 °, the outer angle is bent at 46 °. The method of claim 1,
The touch screen for detecting a user's touch is a liquid crystal display, characterized in that the touch screen further comprises an add-on, on-cell or in-cell type Device.

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