KR20070070030A - LCD and its manufacturing method - Google Patents

Abstract

An FFS type liquid crystal display device capable of adjusting the viewing angle in the up, down, left, and right directions without forming white pixels is obtained.

In an FFS type liquid crystal display device having a display screen made up of a set of pixels, each of the pixels has a display control region in which the liquid crystal molecules are inclined and the liquid crystal molecules are inclined in an up-down or left-right direction. And a viewing angle control region to which a control voltage is applied through a viewing angle control line independent of the common line of the display control region.

Description

Liquid crystal display device and method for manufacturing thereof

1 is a plan view of pixel proximity of an FFS type liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of liquid crystal molecules in a viewing angle control region having left and right common electrodes in an embodiment of the present invention.

3 is a process explanatory diagram of a method of manufacturing a liquid crystal display device in an embodiment of the present invention.

FIG. 4 is a plan view of a pixel vicinity formed by the manufacturing process of FIG. 3 of the liquid crystal display according to the exemplary embodiment of the present invention.

FIG. 5 is a diagram illustrating a luminance distribution depending on a viewing angle according to voltage application of a viewing angle control region in an embodiment of the present invention.

6 is another plan view of pixel proximity of an FFS type liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 7 is another diagram illustrating a luminance distribution depending on a viewing angle by applying a voltage to a viewing angle control region in an exemplary embodiment of the present invention.

8 is an explanatory diagram of a conventional liquid crystal display device having a secret mode.

9 is a view showing the shape of the liquid crystal molecules when the vertical alignment liquid crystal display device is viewed from the front.

FIG. 10 is a view showing the shape of liquid crystal molecules when the vertically aligned liquid crystal display is tilted. FIG.

11 is a diagram showing a specific configuration for controlling the confidentiality of the display.

FIG. 12 is a diagram illustrating an arrangement state of liquid crystal molecules of each subpixel in FIG. 11.

Fig. 13 is a plan view of a proximity pixel of a conventional FFS type liquid crystal display device.

Fig. 14 is an explanatory view of the operation of liquid crystal molecules by applying voltage of a conventional FFS type liquid crystal display device.

Explanation of symbols for the main parts of the drawings

10: display control region 11, 11a, 11b: common electrode

20: viewing angle control area 21a, 21b: common electrode

30: viewing angle control line 40: substrate

41: gate electrode 42: gate pad

43: data pad 44: gate insulating film

45 source electrode 46 drain electrode

47a: first passivation layer 47b: second passivation layer

48: pixel electrode 49: viewing angle control electrode

50: photo acrylic layer 51a, 51b: common electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of controlling the viewing angle and a manufacturing method thereof, and more particularly, to a structure having a FFS (Fringe Field Switching) structure.

Liquid crystal displays, especially liquid crystal displays using TFTs (Thin Film Transistors), are widely used in mobile phones and large-sized televisions.

Among the display devices used individually, there is a demand for a display device which is visible to the person who is using it, but which is invisible even when viewed from the side.

In particular, it is desirable that a plurality of people share the display screen at some time, and only a person can use it at some time.

8 is an explanatory diagram of a conventional liquid crystal display device having a secret mode.

A display having a secret mode as shown in Fig. 8 has been proposed (see Patent Document 1, for example).

In FIG. 8, as a backlight which irradiates a liquid crystal panel from the back side, the thing with strong directivity is used.

For example, a polymer dispersed liquid crystal panel (scattering and non-scattering switching) is formed between the normal liquid crystal panel and the directional backlight to switch the scattering state and the non-scattering state.

When the scattering layer is in the non-scattering state, since the light from the backlight is irradiated only to the front, the inclined display cannot be seen.

On the other hand, when the scattering layer is in the scattering state, since the backlight light is also examined in the inclined direction, the inclined display can be seen and the display can be shared by a plurality of people.

In this case, a problem arises that it becomes expensive because it is necessary to make a special liquid crystal panel unlike a normal liquid crystal panel.

As a measure for solving this problem, a method using a vertical alignment liquid crystal display has been proposed. Hereinafter, the basic principle will be described with reference to FIGS. 9 to 12.

9 is a view showing the shape of the liquid crystal molecules when the vertical alignment liquid crystal display is viewed from the front.

The liquid crystal molecules are vertically aligned in the state where no voltage is applied in FIG. 9 (a). When the voltage is applied as in FIG. 9 (b), the liquid crystal molecules are inclined in the upward direction.

The polarizer and the analyzer are directed to the absorption axis in the vertical direction and the left and right directions, respectively.

Fig. 9A shows the case where the voltage-free vertically aligned liquid crystal panel is viewed from the front. The birefringence of liquid crystal molecules is not expressed and all the light does not leak.

FIG. 9B is a front view of the liquid crystal panel to which voltage is applied. The optical axis of the liquid crystal molecules is parallel to the absorption axis of the polarizer. As a result, birefringence is also not seen and all light is not leaked.

10 is a view showing the shape of the liquid crystal molecules when the vertically aligned liquid crystal display device is viewed obliquely.

As shown in Fig. 10A, when no voltage is applied, the axis of the liquid crystal molecules appears parallel to the absorption axis of the analyzer, so that light does not leak.

On the other hand, as shown in Fig. 10B, when voltage is applied, the axis of the liquid crystal molecules is shifted from the axis of the polarizer and the analyzer, and birefringence is expressed, and light is leaked.

When the light leakage is used, the display contrast falls to the extreme in the left and right directions, so that even if the display is seen in the lateral direction, it is impossible to know what is written. Therefore, this phenomenon can be used to control the confidentiality of the display.

11 is a diagram showing a specific configuration for controlling the confidentiality of the display.

In Fig. 11, a subpixel of white (W) is further formed in a subpixel of RGB in one pixel.

12 is a diagram illustrating an arrangement state of liquid crystal molecules of each subpixel in FIG. 11. As shown in Fig. 12, the alignment state of the liquid crystal molecules of the pixel portion of the bag is made up and down unlike the other RGB.

On the other hand, when no voltage is applied to the portion of the white pixel, all of these portions do not contribute to the display, so that normal display is realized.

On the other hand, when a voltage is applied to the part of the white pixel, the white display is performed in the left and right directions on the entire surface. As a result, the contrast of the display is lowered to the left and right visual orientation, and the fear of showing the display to others is reduced.

Next, a conventional liquid crystal display device of a conventional FFS (Fringe Field Switching) system in which the viewing angle is improved by setting the shape of the common electrode to a "<" shape will be described.

Fig. 13 is a plan view of each RGB pixel of the conventional FFS type liquid crystal display device. 14 is an explanatory view of the operation of liquid crystal molecules by applying a voltage of a conventional FFS type liquid crystal display device.

As shown in Fig. 13, in the conventional liquid crystal display device, a "<" shaped common electrode is formed to define the falling direction of the liquid crystal.

In the state where no voltage is applied, the liquid crystal molecules are directed in the vertical direction as shown in Fig. 14A.

On the other hand, in the voltage application state, the liquid crystal molecules fall in the direction determined by the influence of the inclined electric field by the common electrode, that is, the direction perpendicular to the extended direction of the common electrode, as shown in FIG.

As a result, the liquid crystal can fall in two directions corresponding to the " " characters and a liquid crystal display device having a good viewing angle is realized.

Patent Document 1: Japanese Patent Application Laid-Open No. 5-72529

However, the liquid crystal display according to the prior art has the following problems.

First, although it is set as the structure which forms a white pixel, it is necessary to form a white resin newly, and driving becomes different from the former.

Second, the visibility of the specific direction is improved by making the common electrode "<", but it cannot be controlled to have a secrecy as needed.

Disclosure of Invention The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an FFS type liquid crystal display device and a method of manufacturing the same, which can adjust the viewing angle in the up, down, left, and right directions without forming a white pixel.

The liquid crystal display device according to the present invention is an FFS type liquid crystal display device having a display screen composed of a set of pixels, wherein each pixel includes a display control area in which the liquid crystal molecules are inclined, and an up or down or left or right orientation. And a viewing angle control region in which the liquid crystal molecules are tilted and the control voltage is applied through the viewing angle control line independent of the common line of the display control region.

In addition, a method of manufacturing a liquid crystal display device according to the present invention includes forming a gate electrode, a gate pad, and a data pad on a substrate, forming a gate insulating film, and forming a source electrode and a drain electrode on the gate electrode. A second step of forming, a third step of forming a contact hole after the first passivation layer and the photoacrylic layer are sequentially formed on the entire surface of the substrate, a common electrode for the display control region in which the liquid crystal molecules are oriented and tilted; And a fourth process of separating and forming a common electrode for viewing angle control in which the liquid crystal molecules are tilted in up, down, and left and right directions, and a fifth process of forming a contact hole after forming a second passivation layer on the entire surface of the substrate. And forming a pixel electrode in the display control area and vertically and horizontally in a viewing angle control area corresponding to each pixel display control area. Such that liquid crystal molecules are inclined in the direction to having a sixth step of forming the viewing angle control electrode.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of the liquid crystal display device and its manufacturing method which concern on this invention is described with reference to drawings.

1 is a plan view of a pixel proximity of an FFS type liquid crystal display according to an exemplary embodiment of the present invention. In FIG. 1, one pixel includes a display control region 10 and a viewing angle control region 20.

The display control area 10 is an area in which the liquid crystal molecules are inclined by the " " shaped common electrode 11 formed to define the direction in which the liquid crystal falls.

The "<" shaped common electrode 11 as described above is formed in the display control region 10 of each RGB pixel, and furthermore, by applying a voltage to the pixel to be displayed, it corresponds to the "<" It is possible to knock down the liquid crystal in two directions, so that color display with a good viewing angle is possible.

On the other hand, the viewing angle control area 20 is an area in which the liquid crystal molecules are tilted in the up-down direction or the left-right direction, and the control voltage is applied through the viewing angle control line 30 separate from the display control area 10.

In the viewing angle control region 20, either one of the left and right common electrodes 21a as shown in FIG. 1 or the common electrode 21b of the up and down directions described later is formed.

As shown in FIG. 1, an applied voltage is supplied to the viewing angle control region 20 through a viewing angle control line 30 separate from the display control region 10. In addition, the independent common line for the viewing angle control region 20 can increase the aperture ratio by forming the viewing angle control line 30 as a transparent electrode. In addition, since the common lines are independent, the voltage applied to the viewing angle control region 20 can be input as an arbitrary waveform.

Next, the operation of the liquid crystal molecules in the applied / non-applied state of the voltage in the viewing angle control region 20 will be described.

FIG. 2 is a diagram illustrating the operation of liquid crystal molecules in the viewing angle control region 20 having the common electrodes 21a in the left and right directions in the embodiment of the present invention.

In the viewing angle control region 20 having the left and right common electrodes 21a, when no voltage is applied, the liquid crystal is in a horizontal state as shown in FIG. Therefore, the display of the viewing angle control area 20 becomes black and does not affect the entire display.

This is the same for the front, top, bottom, left, and right angles, and the display itself by RGB pixels is used naturally.

On the other hand, in the viewing angle control region 20 having the left and right common electrodes 21a, when a voltage is applied, as shown in FIG. 2 (b), the liquid crystal molecules are formed in the center of the common electrode and the center between the common electrodes. Will be in a vertical position.

Therefore, when viewed only in the left and right direction, bright light is transmitted to the part where the common electrode 21a in the left and right directions enters. On the contrary, in the vertical direction, light does not escape to the part where the common electrode 21a in the left and right directions enters.

On the other hand, in the viewing angle control region 20 having the common electrode 21b in the up and down direction, when a voltage is applied, the liquid crystal molecules in a direction different from that of FIG. It is in a state entered vertically in the middle part between.

Therefore, when viewing only the left and right directions, light exits at the portion where the common electrode 21b in the up and down directions enters. On the contrary, when viewed in the vertical direction, bright light is transmitted to the portion where the common electrode 21b in the vertical direction is inserted.

As a result, in a state where a voltage is applied to the viewing angle control region 20, the viewing angle control region having the left and right common electrodes 21a has a white and an up and down common electrode with respect to the viewing angle in the left and right directions. The viewing angle control area having 21b is recognized as black.

On the contrary, with respect to the viewing angle in the vertical direction, the viewing angle control region having the common electrode 21a in the left and right directions is black, and the viewing angle control region having the common electrode 21b in the up and down directions is recognized as white.

When these patterns are superimposed on a normal display pattern by RGB pixels, and the patterns are viewed in the left-right direction and the up-down direction in each pixel, it is impossible to know what is written, and the display information can have confidentiality.

As described above, in the viewing angle control region 20 corresponding to each display control region 10, either one having the common electrode 21a in the left and right directions or one having the common electrode 21b in the vertical direction is formed. By applying a voltage to the viewing angle control region 20, it is possible to brighten the display of both visual fields in the left-right direction or the vertical direction.

Therefore, display having desired confidentiality can be performed by arranging pixels having the common electrodes 21a in the left and right directions and pixels having the common electrodes 21b in the up and down directions at desired positions in the display screen.

The process of manufacturing such viewing angle control area | region 20 is demonstrated.

3 is a process explanatory diagram of a method of manufacturing a liquid crystal display device in an embodiment of the present invention.

First, the gate electrode 41, the gate pad 42, and the data pad 43 are formed on the substrate 40 by the first process.

Subsequently, in the second step, the gate insulating film 44 is formed, the a-Si layer and the n ⁺ a-Si layer are sequentially formed, a metal layer is formed on the n ⁺ a-Si layer, and the hole is formed by etching. The source electrode 45 and the drain electrode 46 are formed on the gate electrode 41.

Subsequently, after the first passivation layer 47a and the photo acryl layer 50 (or insulating layer) are sequentially formed on the entire surface of the substrate 40 by the third step, contact holes are formed.

Next, by the fourth process, separate common electrodes 51a and 51b are formed on the channel and the display control region 10. The common electrode 51b formed in the display control region 10 corresponds to the common electrode 11 in FIG. 1.

Next, by the fifth process, the second passivation layer 47b is formed on the entire surface of the substrate 40 and then contact holes are formed.

By the sixth step, the pixel electrode 48 is formed in the display control region 10 in which the liquid crystal molecules are tilted and the orientation is controlled so that the liquid crystal molecules are tilted in the vertical and horizontal directions. The viewing angle control electrode 49 is further formed in the viewing angle control region 20 to which the control voltage is applied through the control line 30.

FIG. 4 is a plan view of pixel proximity formed by the manufacturing process of FIG. 3 of the liquid crystal display device in the embodiment of the present invention, and shows an example of the plan view of the R pixel.

As a result of this process, the structure of FIG. 4 is finally formed.

As shown in Fig. 4, the viewing angle control region 20 can achieve the role of secrecy of the display in the left and right directions or the up and down directions, so that it is not necessary to make the colored layer by the color filter.

By passing through the six mask process as described above, the independent viewing angle control line 30 can be formed as a transparent electrode, and by applying the mask of the sixth step, It is also possible to embed the viewing angle control region 20 having the common electrode.

FIG. 5 is a view illustrating luminance distribution depending on viewing angle depending on voltage applied to the viewing angle control region 20 according to an exemplary embodiment of the present invention, and when the common electrode 21a in the left and right directions is formed as the viewing angle control region 20. Luminance distribution.

When no voltage is applied to the viewing angle control region 20, the inclination directions of the front, top, bottom, left and right luminances are the luminance corresponding to the black screen.

On the other hand, when a voltage is applied to the viewing angle control region 20, the front side is black, but the tilted direction in the left and right is transmitted through the light, thereby brightening.

As a result, since light leaks only in the inclined direction of the left and right directions, it becomes difficult to recognize the displayed screen when viewed in the inclined direction of the left and right directions, thereby enabling confidentiality of information.

Similarly, when the common electrode 21b in the vertical direction is formed in the viewing angle control region 20, light is leaked only in the inclined direction of the vertical direction, so that the screen displayed when viewed in the inclined direction of the vertical direction is recognized. It becomes difficult to do so that it is possible to have confidentiality on the information.

6 is another plan view of pixel proximity of an FFS type liquid crystal display according to an exemplary embodiment of the present invention.

6 (a) shows the viewing angle control region 20 having the common electrodes 21a in the left and right directions, and FIG. 6 (b) shows the viewing angle control region 20 having the common electrodes 21b in the up and down directions. have.

In Fig. 6 (a), in order to improve the visibility in the left and right directions, the display control region 10 is arranged with the " " shaped common electrodes 11a at predetermined intervals in the horizontal direction. In addition, in the viewing angle control region 20, left and right common electrodes 21a are formed so as to have the confidentiality of the information in the left and right directions as necessary.

Meanwhile, in FIG. 6B, in order to improve visibility in the up and down direction, the common electrode 11b having a "<" shape is arranged at predetermined intervals in the longitudinal direction in the display control region 10. In addition, the viewing angle control region 20 is provided with a common electrode 21b in the vertical direction so as to have information confidentiality in the vertical direction as needed.

By appropriately disposing the pixel having the structure of FIG. 6 (a) and the pixel having the structure of FIG. 6 (b) in one display screen, the visibility in the up, down, left, and right directions is improved as necessary. Display having information confidentiality in the up, down, left, and right directions is possible.

FIG. 7 is another view showing luminance distribution depending on the viewing angle depending on the voltage applied to the viewing angle control region 20 according to the embodiment of the present invention, and the pixel having the structure of FIG. The luminance distribution in the case where the pixel having a structure of) is appropriately arranged.

When no voltage is applied to the viewing angle control region 20, the inclination directions of the front, top, bottom, left and right luminances are the luminance corresponding to the black screen. Accordingly, the viewing angle control region 20 may improve visibility in the up, down, left, and right directions by operating the common electrodes 11a and 11b of the display control region without affecting the display information.

On the other hand, when a voltage is applied to the viewing angle control region 20, the front side is black due to the operation of the common electrodes 21a and 21b of the viewing angle control region, but the tilted directions in the up, down, left, and right sides are transmitted to be bright. As a result, the information in the up, down, left, and right directions may be confidential.

As described above, according to the embodiment of the present invention, in the FFS type liquid crystal display device, when the visibility is improved by using the "<" shaped common electrode, the viewing angle control area which can be oriented independently of the display control area The liquid crystal display device capable of adjusting the viewing angle in the vertical direction or the horizontal direction can be obtained by forming the?

In addition, in the viewing angle control region, by using the transparent electrode as the viewing angle control line without affecting the signal delay due to the thickness of the acrylic layer, the aperture ratio can be improved and a liquid crystal display device having confidentiality in the display information can be obtained. .

According to the present invention, the liquid crystal molecules are controlled to be tilted in the up-down direction or the left-right direction together with the display control area in which the liquid crystal molecules are tilted and controlled through a viewing angle control line independent of the common line of the display control area. By further forming a viewing angle control region to which voltage is applied in one pixel, an FFS type liquid crystal display device and a method of manufacturing the same, which can adjust the viewing angle in the up, down, left, and right directions without forming a white pixel, can be obtained.

Furthermore, by appropriately disposing the viewing angle control region in the left and right directions and the viewing angle control region in the up and down directions within the display screen, a liquid crystal display device having confidentiality of information in the up, down, left and right directions can be realized. In addition, it is not necessary to design a color filter in the viewing angle control area, so that the cost can be reduced.

Claims (3)

In the FFS type liquid crystal display device having a display screen composed of a set of pixels, Each one pixel A display control region whose orientation is controlled to tilt the liquid crystal molecules, And a viewing angle control region in which the liquid crystal molecules are tilted in up-down or left-right directions and to which a control voltage is applied through a viewing angle control line independent of a common line of the display control region. The liquid crystal display device according to claim 1, wherein a colored layer by a color filter is not formed on the substrate facing the viewing angle control region. Forming a gate electrode, a gate pad, and a data pad on the substrate; A second step of forming a gate insulating film and forming a source electrode and a drain electrode on the gate electrode; A third process of forming a contact hole after sequentially forming a first passivation layer and a photo acrylic layer on the entire surface of the substrate; A fourth process of separating and forming a common electrode for the display control region in which the liquid crystal molecules are inclined and a common electrode for the viewing angle control in which the liquid crystal molecules are inclined in the vertical and horizontal directions; A fifth process of forming a contact hole after forming a second passivation layer on the entire surface of the substrate; And a sixth step of forming a viewing angle control electrode to form a pixel electrode in the display control region and to incline the liquid crystal molecules in a vertical direction and a horizontal direction to a viewing angle control region corresponding to each pixel display control region. A method of manufacturing an FFS liquid crystal display device.

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