KR20070080340A - Liquid crystal display - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to easily achieve a wide viewing angle and a narrow viewing angle as occasion demands, by forming an auxiliary pixel electrode and an auxiliary common electrode within cutout portions of a pixel electrode and a common electrode respectively, and driving the pixel electrode and the common electrode independently. A pixel electrode(191) is formed on a first insulating substrate. A second insulating substrate is disposed to face the first insulating substrate. A common electrode is formed on the second insulating substrate. A liquid crystal layer is formed between the first insulating substrate and the second insulating substrate. At least one of the pixel electrode and the common electrode includes a first electrode(191a) having a cutout portion and a second electrode(191b) formed within the cutout portion.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

1 is a block diagram of a display device according to an exemplary embodiment of the present invention.

2 is an equivalent circuit diagram of one pixel of a liquid crystal display, which is an example of a display device according to an exemplary embodiment of the present invention.

FIG. 3 is a schematic equivalent circuit diagram of one pixel electrode of the lower panel in one pixel of FIG. 2.

4 is a layout view schematically illustrating one pixel electrode of FIG. 3.

FIG. 5 is a schematic equivalent circuit diagram of an upper panel in one pixel of FIG. 2.

6 is a layout view schematically illustrating a common electrode of the upper panel of FIG. 5.

* Description of the major symbols in the drawings *

100: lower display panel 200: upper display panel

27, 190: cutouts 190, 190a, 190b: pixel electrodes

270, 270a, 270b: common electrode 300: assembly

500: data driver 600: signal controller

800: gray level signal generator

A: 2nd electrode control part S1, S2: Short point

Q1 to Q4: switching elements

The present invention relates to a liquid crystal display device.

The liquid crystal display is one of the most widely used flat panel display devices. The liquid crystal display includes two display panels on which a field generating electrode such as a pixel electrode and a common electrode are formed, and a liquid crystal layer interposed therebetween. The liquid crystal display generates an electric field in the liquid crystal layer by applying a voltage to the field generating electrode, thereby determining the direction of the liquid crystal molecules of the liquid crystal layer and displaying an image by controlling incident polarization.

The liquid crystal display also includes a switching element connected to each pixel electrode and a plurality of signal lines such as a gate line and a data line for controlling the switching element and applying a voltage to the pixel electrode.

Such a liquid crystal display device has a narrower viewing angle than other display devices. Therefore, various methods for widening the viewing angle have been developed. Among them, a method of vertically aligning liquid crystal molecules with respect to the upper and lower display panels, forming a constant cutout in the pixel electrode and the common electrode, and dividing it into multiple domains has been disclosed.

However, the current display device has various functions such as phone banking, text messaging, movies, TV, etc., and functions including personal contents such as phone banking, text messaging, etc. may cause privacy infringement such as leakage of personal information when wide viewing angle is present. Can be.

Accordingly, the technical problem to be achieved by the present invention is to vary the viewing angles when performing a personal task such as phone banking and when using a screen together by watching a movie.

According to an exemplary embodiment of the present invention, a liquid crystal display (LCD) device includes a first insulating substrate, a pixel electrode formed on the first insulating substrate, a second insulating substrate facing the first insulating substrate, and a second insulating substrate. And a liquid crystal layer formed between the formed common electrode and the first insulating substrate and the second insulating substrate, wherein at least one of the pixel electrode and the common electrode is formed on the first electrode including the cutout and the cutout. Consisting of a second electrode.

A first switching element in which the pixel electrode includes a first electrode and a second electrode and is connected to a first gate line, a data line crossing the first gate line, a first gate line, and a data line formed on the first insulating substrate; Further comprising a, the first switching device may be connected to the first electrode.

The display device may further include a second switching element connected to the second gate line, the second gate line, and the data line formed on the first insulating substrate, and the second switching element may be connected to the second electrode.

The display device may further include a third switching device connecting the first gate line and the second gate line.

The common electrode may further include a fourth switching element that includes a first electrode and a second electrode, and connects the first electrode and the second electrode of the common electrode.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

Next, a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the drawings.

1 is a block diagram of a display device according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of one pixel of a liquid crystal display device which is an example of a display device according to an embodiment of the present invention, and FIG. A schematic equivalent circuit diagram of one pixel electrode of a lower panel at one pixel of FIG. 2 is a layout view schematically illustrating one pixel electrode of FIG. 3, and FIG. 5 is a schematic equivalent diagram of an upper panel at one pixel of FIG. 2. 6 is a schematic diagram illustrating a common electrode of the upper panel of FIG. 5.

According to an exemplary embodiment, a display device includes a display panel unit 300, a gate driver 400 connected thereto, a data driver 500, and a gray level signal generator 800 connected to the data driver 500. And a signal controller 600 for controlling them.

Referring to FIGS. 1 and 2, the display panel unit 300 is connected to a plurality of display panel lines G1 -G2n and D1-Dm in an equivalent circuit and arranged in a substantially matrix form. And a plurality of pixels PX constituting a display area DA. The display panel 300 of the liquid crystal display includes lower and upper display panels 100 and 200 and a liquid crystal layer 3 therebetween.

The display signal lines G ₁ -G _{2 n} and D ₁ -D _m transmit a data signal and a plurality of gate lines G ₁ -G _{2 n} that transmit a gate signal (also called a “scan signal”). It includes a data line (D ₁ -D _m ). The gate lines G ₁ -G _{2 n} extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each pixel PX includes at least one switching element (not shown) such as a thin film transistor and at least one capacitor.

Each pixel PX of the liquid crystal display device includes a switching element (not shown) connected to the display signal lines G ₁ -G _n , D ₁ -D _m , and a liquid crystal capacitor C _LC connected thereto. Storage capacitor (C _ST ).

The display panel lines G ₁ -G _n , D ₁ -D _m and the storage capacitor Cst are formed on the lower display panel 100, and the storage capacitor C _ST may be omitted as necessary.

Referring to FIG. 3, the lower panel 100 includes switching elements Q1 and Q2 such as thin film transistors, each of which is a control terminal and a data line connected to gate lines G ₁ -G _n . It is a three-terminal device with an input terminal connected to (D ₁ -D _m ) and an output terminal connected to a liquid crystal capacitor (C _LC ) and a storage capacitor (C _ST ).

2 and 3, the liquid crystal capacitor C _LC has two terminals, the pixel electrode 191 of the lower panel 100 and the common electrode 270 of the upper panel 200 as two terminals. The liquid crystal layer 3 between) functions as a dielectric. As illustrated in FIG. 4, the pixel electrode 191 may include a cutout 190, and may include a main pixel electrode 191a and a subpixel electrode 191b formed in the cutout 190. have. The main pixel electrode 191a and the subpixel electrode 191b are connected to the first switching element Q1 and the second switching element Q2, respectively.

In addition, the lower panel 100 includes a main gate line G1 and a subgate line G2, and has a third switching element Q3 connecting the main gate line G1 and the subgate line G2. .

The gate signal applied to the second switching element Q2 is selected by the third switching element Q3. That is, when the on signal is input to the third switching element Q3, the main gate line G1 and the subgate line G2 are shorted to each other through the third switching element Q3 and transferred along the main gate line G1. The gate signal to be transmitted is similarly transmitted to the subgate line G2. Accordingly, the gate signal input to the first switching element Q1 is also transmitted to the second switch element Q2, so that the second switching element Q2 is also turned on. As a result, the same image voltage is applied to the main pixel electrode 191a and the subpixel electrode 191b. On the contrary, when the off signal is input to the third switching element Q3, the main gate line G1 and the subgate line G2 are electrically separated from each other, and even though the gate signal is input to the first switching element Q1, the second switching element Since the gate signal is not input to Q2, the second switching element Q2 is maintained in the off state. Therefore, the image voltage is applied only to the main pixel electrode 191a and the subpixel electrode 191b is maintained in a floating state.

When the image signal is applied only to the main pixel electrode 191a without the image voltage applied to the subpixel electrode 191b as described above, the cutout 190 serves as a domain dividing means. Therefore, one pixel electrode 191 is divided into a plurality of domains to implement a wide viewing angle.

On the other hand, when an image signal is also applied to the subpixel electrode 191b, an image signal is input to both the main pixel electrode 191a and the subpixel electrode 191b, and an interval between the main pixel electrode 191a and the subpixel electrode 191b. This closes the cutout 190 so that it does not function as a domain dividing means. Therefore, the viewing angle is narrower than when the subpixel electrode 191b is turned off.

The common electrode 270 is formed on the entire surface of the upper panel 200 and receives a common voltage Vcom. The common voltage Vcom is applied to the common electrode 270 through the short points S1 and S2.

The common electrode 270 includes a main common electrode 270a and a sub common electrode 270b as shown in FIGS. 5 and 6. Here, the secondary common electrode 270b is formed in a shape similar to that of the cutout 27 in the cutout 27 of the main common electrode 270a.

The common voltage is always applied to the main common electrode 270a, but the common voltage is applied or blocked to the sub common electrode 270b according to the on / off of the fourth switching element Q4. The fourth switching element Q4 is controlled by the sub common electrode control unit A. FIG.

Like the pixel electrode 191, when the fourth switching element Q4 is turned off, the common electrode 270 is not inputted to the sub-common electrode 270b, but the common voltage is input only to the main common electrode 270a. Therefore, the cutout 27 of the common electrode 270 serves as a domain dividing means to form a plurality of domains, thereby realizing a wide viewing angle.

On the other hand, when a signal is applied to the secondary common electrode 270b, the common electrode 270 because the gap between the primary common electrode 270a and the secondary common electrode 270b is so close that the cutout 27 does not act as a domain dividing means. ), The viewing angle is narrower than when the sub-common electrode 270b is turned off.

When the cutouts 190 and 27 are formed in the pixel electrode 191 and the common electrode 270, the subpixel electrode 191b and the sub common electrode 270b are alternately disposed.

The storage capacitor C _ST is a capacitor that assists the liquid crystal capacitor C _LC . The storage capacitor C _ST is formed by overlapping a separate signal line (not shown) and the pixel electrode 191 provided on the lower panel 100. A predetermined voltage such as the common voltage Vcom is applied to the signal line. However, the storage capacitor C _ST may be formed such that the pixel electrode 191 overlaps the front gate line directly above the insulator.

In order to implement color display, each pixel PX uniquely displays one of a plurality of primary colors (spatial division) or alternately displays a plurality of primary colors (time division) so that the spatial and temporal sum of the primary colors can be achieved. Indicates the desired color. Examples of primary colors include red, green and blue. FIG. 2 illustrates an example of spatial division in which each pixel PX includes a color filter 230 representing one color of primary colors in a corresponding region of the upper panel 200 facing the pixel electrode 191. . Alternatively, the color filter 230 may be formed above or below the pixel electrode 191 of the lower panel 100.

At least one polarizer (not shown) for polarizing light is attached to an outer surface of at least one of the two display panels 100 and 200 of the display panel unit 300.

The gate driver 400 is integrated in the display panel 300 and includes a plurality of driving circuits (not shown). Each driving circuit of the gate driver 400 is connected to one gate line G ₁ -G _n and includes a plurality of thin film transistors. However, the gate driver 400 may be mounted on the display panel 300 in the form of an integrated circuit (IC) chip or on a flexible printed circuit (FPC) film. In the latter case, a flexible printed circuit film is attached onto the display panel unit 300.

The data driver 500 is connected to the data lines D ₁ -D _m of the display panel 300 and selects a gray voltage from the gray signal generator 800 to select the gray voltage as the data voltage D ₁ -D _m. ) Is applied. The data driver 500 may also be a flexible printed circuit (FPC) integrated into the display panel unit 300, mounted on the display panel unit 300 in the form of one or more integrated circuit chips, or attached to the display panel unit 300. ) Can be mounted on the film.

The driving units 400 and 500 or the flexible printed circuit film on which they are mounted are positioned in a peripheral area positioned outside the display area DA in the display panel 300.

The signal controller 600 controls the gate driver 400, the data driver 500, and the like, and may be mounted on a printed circuit board (PCB).

The signal controller 600 generates a selection signal voltage for turning on / off the third switching element Q3 and the fourth switching element Q4 according to the user's mode selection. It is applied to the control terminal of (Q4). The signal line for transmitting the selection signal voltage from the signal controller 600 to the control terminals of the third switching element Q3 and the fourth switching element Q4 is formed to pass through the gate driver 400 and the data driver 500. Alternatively, the control unit of the signal controller 600, the third switching element Q3, and the fourth switching element Q4 may be directly connected through a separate signal line.

As described above, when the auxiliary pixel electrode and the common electrode are formed in the cutouts of the pixel electrode and the common electrode, and driven separately from the pixel electrode and the common electrode, a wide viewing angle and a narrow viewing angle can be easily obtained as necessary.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (6)

First insulating substrate, A pixel electrode formed on the first insulating substrate, A second insulating substrate facing the first insulating substrate, A common electrode formed on the second insulating substrate, A liquid crystal layer formed between the first insulating substrate and the second insulating substrate, At least one of the pixel electrode and the common electrode includes a first electrode including a cutout, and a second electrode formed on the cutout. In claim 1, The pixel electrode includes the first electrode and the second electrode, A first gate line formed on the first insulating substrate, A data line crossing the first gate line, Further comprising a first switching device connected to the first gate line and the data line, The first switching element is connected to the first electrode. In claim 2, A second gate line formed on the first insulating substrate, A second switching element connected to the second gate line and the data line; The second switching element is connected to the second electrode. In claim 3, And a third switching element connecting the first gate line and the second gate line. In claim 1, The common electrode includes the first electrode and the second electrode, And a fourth switching element connecting the first electrode and the second electrode of the common electrode. In claim 1, The pixel electrode and the common electrode include the cutout, And the pixel electrode cutout and the common electrode cutout are alternately arranged.

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