KR100900538B1 - Liquid crystal display - Google Patents

Abstract

The present invention relates to a liquid crystal display device.

In the liquid crystal display according to the present invention, a basic electrode portion for generating a pixel voltage for charging an gradation voltage applied through a current data line in a pixel panel to display an image, a pixel voltage generated in this way, and a front gate And an auxiliary electrode portion for charging the second and third voltages applied through the transistor turned on by the scan signal received through the line to generate an auxiliary voltage, respectively. Allows for texture stabilization.

Liquid crystal display, auxiliary voltage, stabilization, texture and liquid crystal alignment

Description

Liquid crystal display device {A LIQUID CRYSTAL DISPLAY}

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

FIG. 2 is a detailed circuit diagram illustrating the auxiliary electrode shown in FIG. 1 and a pixel part including the same.

3 is a diagram illustrating polarity of each pixel according to the dot inversion driving method.

4 is a detailed circuit diagram illustrating a pixel unit according to a first exemplary embodiment of the present invention.

5 is a detailed circuit diagram illustrating a pixel unit according to a second exemplary embodiment of the present invention.

6 is a diagram illustrating polarity of each pixel according to the vertical line inversion driving method.

7 is a detailed circuit diagram illustrating a pixel unit according to a third exemplary embodiment of the present invention.

8 is a detailed circuit diagram illustrating a pixel unit according to a fourth exemplary embodiment of the present invention.

※ Explanation of code about main part of drawing ※

10: timing controller 20: data driver

30: gate driver 40: LCD panel

41: basic electrode portion 42: auxiliary electrode portion

43: pixel portion

The present invention relates to a liquid crystal display device.

Recently, display devices are also required to be lighter and thinner in accordance with lighter and thinner personal computers and televisions, and according to such demands, liquid crystal displays (LCDs) instead of cathode ray tubes (CRTs) are required. Flat panel displays are being developed.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which an opposite electrode, a color filter, and the like are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed. By applying a different potential to form an electric field to change the arrangement of the liquid crystal molecules, and through this to control the light transmittance is a device that represents the image.

In addition, the liquid crystal display includes a plurality of gate lines that transmit scan signals and data lines that are formed to intersect the gate lines, and which transfer image data, and are formed in regions surrounded by the gate lines and the data lines, respectively, and include gate lines and It includes a plurality of pixels in the form of a matrix connected through a data line and a switching element.

The liquid crystal display starts from an initial twist nematic (TN) mode in which a liquid crystal is twisted, and includes an in-plane switching (IPS) mode, a vertically aligned (VA) mode, and a fringe field switching (FFS) mode. It has been developed in recent years, and its production has been further advanced by incorporating semiconductor technologies such as thin film transistors (hereinafter referred to as TFTs).

However, among various modes of the liquid crystal display, the liquid crystal display according to the VA mode requires an auxiliary voltage having a predetermined size for stabilization of texture and liquid crystal alignment, in addition to the general data driving voltage. However, in the conventional liquid crystal display, the auxiliary voltage rise of such a function is not large, so that a texture may be weakly generated in the case of the monochromatic driving.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve such a problem, and to provide a liquid crystal display device which supplies a sufficient auxiliary voltage to stabilize liquid crystal alignment and texture.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a plurality of data lines formed to intersect a plurality of gate lines and the plurality of gate lines in a matrix form, and a predetermined region in which a grid is arranged between the gate lines and the data lines. An LCD panel formed on the LCD panel, the LCD panel including a plurality of pixel parts connected to the gate line and the data line; A data driver which applies a gray voltage according to image data to the plurality of data lines; And a gate driver sequentially applying scan signals to the plurality of gate lines, wherein the pixel unit includes: a basic electrode unit configured to generate a pixel voltage to charge an gray voltage applied through a current data line to display an image; And an auxiliary electrode unit configured to charge the generated pixel voltage and second and third voltages applied through a transistor turned on by a scan signal received through a front gate line to generate an auxiliary voltage.

At this time, the auxiliary electrode unit according to an embodiment of the present invention, the second and third transistors are turned on by the scan signal applied through the front gate line to transfer the second and third voltage; And a second capacitor charging the difference between the second and third voltages transmitted through the second and third transistors.

In addition, the data driver according to the exemplary embodiment of the present invention transmits a gray voltage having different polarities or a gray voltage having the same polarity to each pixel forming one pixel column.

In addition, source terminals of the second and third transistors that transfer the gray voltage may be connected to a common electrode voltage terminal, a front data line, or an auxiliary data line.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

1, a liquid crystal display according to an exemplary embodiment of the present invention includes a timing controller 10, a data driver 20, a gate driver 30, and an LCD panel 40. Comprising a plurality of pixel portion 43, each pixel portion 43 includes a basic electrode portion 41 and the auxiliary electrode portion 42, respectively.                     

The timing controller 10 may include a horizontal synchronous signal Hsync for distinguishing lines from R, G, and B image data RGB from an external graphic controller (not shown), and a vertical synchronous signal Vsync for distinguishing each frame. When the data enable signal DE and the main clock signal MCLK, which are at a high level, are input only during a period in which data is output to indicate an area where data enters, the data driver 20 and the gate are based on the input signal. It generates and transmits a signal for controlling the driving of the driver 30.

The data driver 20 converts the R, G, and B image data RGB transmitted from the timing controller 10 into corresponding gray voltages in synchronization with a clock, and then transfers the changed gray voltages from the timing controller 10. According to the LOAD signal, it is delivered to each data line.

The gate driver 30 receives the gate clock signal Gate Clk and the vertical line start signal STV from the timing controller 10, and receives the voltages Von and Voff from the driving voltage generator (not shown). The gate-on signals G1, G2, ..., Gn are sequentially output to the gate lines of the LCD panel 40, thereby opening the way for the voltage value of each pixel to be transmitted to the corresponding pixel.

The LCD panel 40 may include m data lines arranged in a column direction, n gate lines arranged in a row direction orthogonal to the data lines, and an auxiliary data line for being applied to an auxiliary electrode. And a plurality of pixel parts 43 formed in a predetermined region lattice arranged between the data line and the gate line, one end of which is connected to the gate line and the other end of which is connected to the data line.                     

The plurality of pixel parts 43 may include a basic electrode part 41 for generating a pixel voltage for charging an gray voltage transmitted through a current data line to display an image, the generated pixel voltage, a front data line, Each of the auxiliary electrode units 42 may be configured to charge a voltage applied through the common electrode voltage or the auxiliary data line to generate an auxiliary voltage according thereto. In this case, the auxiliary voltage generated through the auxiliary electrode part 42 may be used for the purpose of stabilizing texture and liquid crystal alignment, and in some cases, may be used for other purposes.

An embodiment of the pixel portion 43 including the basic electrode portion 41 and the auxiliary electrode portion 42 is shown in FIG. 2. FIG. 2 is a detailed circuit diagram of the pixel unit 43 shown in FIG. 1.

As shown in FIG. 2, the pixel portion 43 according to an exemplary embodiment of the present invention includes a basic electrode portion 41 including a first transistor Tn and a first capacitor Cn, and second and third transistors. And an auxiliary electrode portion 42 including T1 and T2 and a second capacitor Cn '.

Each connection relationship between the pixel units 43 constituting such a structure will be described below.

First, the source terminal of the first transistor Tn in the basic electrode part 41 is connected to the current data line Dn, the gate terminal is connected to the current gate line Gn, and the drain terminal is the first capacitor. It is connected to one terminal of (Cn). In this case, the other terminal of the first capacitor Cn is connected to the common electrode voltage Vcom terminal.

Next, the gate terminals of the second and third transistors T2 and T3 of the auxiliary electrode part 42 are connected to each other and are connected to the front gate line Gn-1, and the second and third transistors T1, The source terminal of T2) is connected to the first and second external voltage terminals E1 and E2, respectively, and each drain terminal is connected to one side and the other terminal of the second capacitor Cn ', respectively.

Here, the first and second voltages V _E1 and V _E2 applied from the outside may be the common electrode voltage Vcom, and the gray voltage or the auxiliary data line applied through the front data line Dn-1. It may be a voltage applied through.

An operation process of the pixel unit 43 having such a structure will be described below.

First, when the gate-on voltage Von is applied through the front gate line Gn-1, the second and third transistors T1 and T2 connected to the front gate line Gn-1 are turned on. On, the second capacitor Cn 'is charged with an external voltage equal to the first and second external voltage differences V _{E1 -E2} .

Thereafter, when the gate-off voltage Voff is applied to the front gate line Gn-1 and the gate-on voltage Von is applied to the current gate line Gn, the first transistor Tn is turned on. As a result, the first capacitor Cn is charged with the voltage V _Dn currently applied through the data line Dn. At this time, since the second and third transistors T1 and T2 are turned off, the voltage charged in the second capacitor Cn 'is maintained because there is no path to be discharged.

Therefore, the auxiliary voltage through the auxiliary electrode part 42 is determined as the voltage {current voltage V _Dn + external voltage difference V _{E1 -E2} applied} through the data line.

In this case, the auxiliary electrode unit 42 according to the present invention adjusts the external voltage difference V _{E1 -E2} to be as large as the driving voltage V _Dn supplied to the current data line, thereby adjusting the size of the auxiliary voltage. It can be up to twice the voltage (V _Dn ). For example, when the basic voltage (data voltage, V _Dn ) generated through the basic electrode part 41 is 5V, the auxiliary voltage generated through the auxiliary electrode part 42 may be 10V maximum.

The generated auxiliary voltage controls the tilt direction of the liquid crystal molecules constituting the liquid crystal display device in a predetermined direction to achieve liquid crystal alignment stabilization and texture reduction. If this is mentioned for a while, it is as follows.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which a common electrode, a color filter, and the like are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed. By applying, it forms an electric field to change the arrangement of the liquid crystal molecules, and through this to adjust the light transmittance is an apparatus for displaying an image.

However, before applying different potentials to the pixel electrode and the common electrode of the liquid crystal display, if the auxiliary voltage generated according to the embodiment of the present invention is applied to the corresponding electrode, the liquid crystal alignment and texture stabilization are largely performed by two effects. Can be achieved.                     

In general, since the voltages of the pixel electrode and the auxiliary electrode to which the data voltage is applied are different, this generates an electrode horizontal electric field, and the tilt direction of the liquid crystal is determined by the generated horizontal electric field. This has two effects. First, the liquid crystal molecules are inclined in a specific direction in advance by the applied auxiliary voltage. Therefore, the liquid crystal molecules inclined by the image signal subsequently applied are inclined along the liquid crystal molecules inclined in advance by the auxiliary voltage. At this time, the inclination direction of the liquid crystal initially determined by the auxiliary voltage leads the inclination direction of the liquid crystal molecules of the entire liquid crystal layer.

Second, the tilt direction of the liquid crystal does not change during the frame period by the direction of the horizontal electric field, and serves to keep it constant. This principle makes it possible to achieve liquid crystal alignment and texture stabilization.

Next, the first and second embodiments in which such an embodiment is applied to the liquid crystal display of the dot inversion driving method will be described below.

First, the dot inversion driving method is a method of driving an image signal to be positively and negatively repeated with respect to the common electrode in order to prevent the liquid crystal from deteriorating. An example of such a display is shown in FIG.

FIG. 3 is a diagram illustrating polarity of each pixel according to a dot inversion driving method. As illustrated, pixels in one pixel column have different polarities, and pixels in a pixel column sequentially adjacent to the pixel column are illustrated. They also have different polarities.                     

A process of generating an auxiliary voltage in the dot inversion driving type liquid crystal display and a structure thereof will be described below.

 4 is a detailed circuit diagram of the pixel portion 43 according to the first embodiment of the present invention.

Referring to FIG. 4, the pixel portion 43 according to the first embodiment of the present invention includes the basic electrode portion 41 and the auxiliary electrode portion 42, as in the above-described embodiment. 41 and the auxiliary electrode portion 42 also have the same configuration.

However, the internal connection structure in the auxiliary electrode part 42 is different. That is, in the first embodiment of the present invention, the first external voltage V _E1 is the common electrode voltage Vcom, and the second external voltage V _E2 is applied to the data voltage Dn-1. V _Dn-1 ). In addition, the front end data voltage V _Dn-1 is a voltage having a polarity opposite to that of the current pixel, and the common electrode voltage Vcom is 0V.

A connection structure of the pixel unit having such a characteristic is as follows. Prior to this, the internal configuration and connection structure of the basic electrode portion 41 according to the second to fourth embodiments to be described later are the same as the above-described embodiment will be omitted. Therefore, in the second to third embodiments to be described later, only the internal connection structure of the auxiliary electrode unit and the operation process of the pixel unit will be described.

In other words, each gate terminal of the second and third transistors T1 and T2 of the auxiliary electrode part 42 is connected to each other and is connected to the front gate line Gn-1, and the source of the second transistor T1 is provided. The terminal is connected to the first external voltage terminal E1 (common electrode voltage terminal), and the drain terminal is connected to one terminal of the second capacitor Cn '.

The other terminal of the second capacitor Cn 'is connected to the drain terminal of the third transistor T2, and the source terminal of the third transistor T2 is connected to the front end data line Dn-1. .

An operation process of the pixel unit 43 forming the connection structure will be described below.

First, when the gate-on voltage Von is applied through the front gate line Gn-1, the second and third transistors T1 and T2 connected to the front gate line Gn-1 are turned on. on, the second capacitor Cn 'is provided with a second external voltage V _E2 , that is, a data voltage V _Dn-1 , which is applied to the front data line _Dn-1 . A voltage having a polarity opposite to that of the current pixel, for example, about 5V, is charged.

Thereafter, when the gate-off voltage Voff is applied to the front gate line Gn-1 and the gate-on voltage Von is applied to the current gate line Gn, the first transistor Tn is turned on. ), The first capacitor Cn is charged with a data voltage V _Dn (for example, about 5V) currently applied to the data line Dn. At this time, since the second and third transistors T1 and T2 are turned off, the voltage charged in the second capacitor Cn 'is maintained because there is no path to be discharged.

Therefore, the auxiliary voltage generated through the auxiliary electrode part 42 is the data voltage V _Dn-1 , which is supplied to the front end and the current data line. The sum of V _Dn ) is 10V, and the basic voltage generated through the basic electrode part 41 becomes 5V, which is a driving voltage currently supplied to the data line V _Dn .

That is, the auxiliary voltage corresponding to twice the basic voltage is generated through the auxiliary electrode part 42.

Next, the liquid crystal display according to the second embodiment will be described. 5 is a detailed circuit diagram of the pixel portion 43 according to the second embodiment of the present invention.

As illustrated in FIG. 5, the pixel portion 43 according to the second exemplary embodiment of the present invention includes the basic electrode portion 41 and the auxiliary electrode portion 42, as mentioned above, and the basic electrode portion 41. The internal structure and connection structure of) are also the same.

However, in the second embodiment of the present invention, the first external voltage V _E1 is the data voltage V _Dn-1 applied to the front data line _Dn-1 , and the second external voltage V _E2 is common. The electrode voltage Vcom may be a voltage applied through the auxiliary data line in some cases. In addition, the front end data voltage V _Dn-1 has the same polarity as that of the current pixel.

The auxiliary electrode in the pixel portion having such characteristics will be described below.

Gate terminals of the second and third transistors T1 and T2 of the auxiliary electrode part 42 are connected to each other and are connected to the front gate line Gn-1, and a source terminal of the second transistor T1 is a current pixel. Is connected to the data line Dn-1 that can receive the voltage V _Dn-1 having the same polarity as that of. The drain terminal of the second transistor T1 is connected to the second capacitor Cn '. It is connected to one terminal of.

The other terminal of the second capacitor Cn 'is connected to the drain terminal of the third transistor T2, and the source terminal of the third transistor T2 is connected to the common electrode voltage terminal, which is the second external voltage terminal E2. It is.

An operation process of the pixel unit 43 forming the connection structure will be described below.

First, when the gate-on voltage Von is applied through the front gate line Gn-1, the second and third transistors T1 and T2 are turned on, and the second capacitor Cn 'is sheared. The data voltage V _Dn-1 , a voltage having the same polarity as that of the current pixel, for example, about 5 V, is charged.

Thereafter, when the gate-off voltage Voff is applied to the front gate line Gn-1 and the gate-on voltage Von is applied to the current gate line Gn, the first transistor Tn is turned on. ), The first capacitor Cn is charged with a data voltage V _Dn (for example, about 5V) currently applied to the data line Dn.

At this time, since the second and third transistors T1 and T2 are turned off, the voltage charged in the second capacitor Cn 'is maintained because there is no path to be discharged.

Therefore, the auxiliary voltage through the auxiliary electrode part 42 is equal to the front end and current data voltages V _Dn−1 , Is charged to a voltage of 10V, which is the sum of V _Dn ).

Next, the third and fourth embodiments in which such an embodiment is applied to the liquid crystal display of the vertical line inversion driving method will be described below.

First, the vertical line inversion driving method is a method of driving the polarity of each vertical line to repeat positive and negative, and a display example of such a method is illustrated in FIG. 6.

FIG. 6 is a diagram illustrating polarity for each line according to the vertical line inversion driving method. As illustrated, a plurality of pixels constituting one pixel column have the same polarity, and each pixel in a pixel column sequentially adjacent to the pixel column is illustrated. The pixels also have the same polarity. However, each pixel column has different polarities.

The principle and structure of the auxiliary voltage generation of the liquid crystal display according to the vertical line inversion driving method will be described below.

7 is a detailed circuit diagram of the pixel portion 43 according to the third embodiment of the present invention.

As illustrated in FIG. 7, the pixel portion 43 according to the third exemplary embodiment of the present invention includes the basic electrode portion 41 and the auxiliary electrode portion 42, as described above. The configuration and connection structure of the 41 and the auxiliary electrode unit 42 are also the same as in the first embodiment.

However, in the third embodiment of the present invention, the data voltage V _Dn-1 applied through the front data line Dn-1 has the same polarity as the data voltage currently applied to the pixel.

The auxiliary electrode in the pixel portion will now be described.

Gate terminals of the second and third transistors T1 and T2 of the auxiliary electrode part 42 are connected to each other and are connected to the front gate line Gn-1, and a source terminal of the second transistor T1 is connected to the first terminal. The drain terminal of the second transistor T1 is connected to one terminal of the second capacitor Cn ', which is connected to the common electrode voltage terminal which is the external voltage terminal E1.

The other terminal of the second capacitor Cn 'is connected to the drain terminal of the third transistor T2, and the source terminal of the third transistor T2 transfers the data voltage having the same polarity as that of the current pixel. It is connected to the line Dn-1.

An operation process of the pixel unit 43 forming the connection structure will be described below.

First, when the gate-on voltage Von is applied through the front gate line Gn-1, the second and third transistors T1 and T2 are turned on, and the second capacitor Cn 'is sheared. The data voltage V _Dn-1 , a data voltage having the same polarity as that of the current pixel, for example, about 5 V, is charged.

Then, when the gate-on voltage (Von) is applied to the current gate line (Gn), the first transistor (Tn) is turned on (turn on), the data applied to the current data line (Dn) to the first capacitor (Cn) The voltage V _Dn , for example about 5V, is charged. At this time, since the second and third transistors T1 and T2 are turned off, the voltage charged in the second capacitor Cn 'is maintained because there is no path to be discharged.

Therefore, the auxiliary voltage through the auxiliary electrode part 42 is equal to the front end and current data voltages V _Dn−1 , Charged to a voltage of 10V, which is the sum of V _Dn ), the basic voltage generated through the basic electrode part 41 becomes 5V, which is a driving voltage currently supplied to the data line V _Dn .

That is, the auxiliary voltage corresponding to twice the basic voltage is generated through the auxiliary electrode part 42, and the generated auxiliary voltage controls the pre-tit of the liquid crystal molecules constituting the liquid crystal display. Liquid crystal orientation stabilization and texture reduction due to this.

Next, a fourth embodiment of the present invention will be described.

8 is a detailed circuit diagram of the pixel portion 43 according to the fourth embodiment of the present invention.

As illustrated in FIG. 8, the pixel portion 43 according to the fourth exemplary embodiment of the present invention includes the basic electrode portion 41 and the auxiliary electrode portion 42, as described above. 41) and the connection structure in the auxiliary electrode part 42 also have the same structure and connection structure as the above-mentioned 2nd Embodiment.

However, in the fourth exemplary embodiment of the present invention, the front data voltage V _Dn-1 is a voltage having a polarity different from that of the current pixel.

The auxiliary electrode in the pixel portion having such characteristics will be described below.

Gate terminals of the second and third transistors T1 and T2 of the auxiliary electrode part 42 are connected to each other and are connected to the front gate line Gn-1, and a source terminal of the second transistor T1 is currently The drain terminal of the second transistor T1 is connected to the front data line _Dn-1 that transfers the data voltage V _Dn-1 having a polarity different from that of the pixel. It is connected to one terminal of.

The other terminal of the second capacitor Cn 'is connected to the drain terminal of the third transistor T2, and the source terminal of the third transistor T2 is currently connected to the data line Dn.

An operation process of the pixel unit 43 forming the connection structure will be described below.

First, when the gate-on voltage Von is applied through the front gate line Gn-1, the second and third transistors T1 and T2 are turned on, and the second capacitor Cn 'is sheared. The data voltage V _Dn-1 , a voltage having a polarity opposite to that of the current pixel, for example, about 5 V, is charged.

Thereafter, when the gate-off voltage Voff is applied to the front gate line Gn-1 and the gate-on voltage Von is applied to the current gate line Gn, the first transistor Tn is turned on. ), The first capacitor Cn is charged with a data voltage V _Dn (for example, about 5V) currently applied to the data line Dn.

At this time, since the second and third transistors T1 and T2 are turned off, the voltage charged in the second capacitor Cn 'is maintained because there is no path to be discharged.                     

Therefore, the voltage charged in the second capacitor Cn 'is equal to the front end and the current data voltages V _Dn-1,. 10 V is the sum of V _Dn ), and this charged auxiliary voltage is used for liquid crystal alignment and texture stabilization.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the claims or in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The liquid crystal display according to the present invention has an effect of achieving liquid crystal alignment and texture stabilization through an auxiliary voltage charged with both data voltages transmitted through front and current data lines.

Claims (8)

A plurality of data lines formed to intersect the plurality of gate lines and the plurality of gate lines in a matrix form, and are formed in a predetermined region lattice arranged between the gate lines and the data lines, and are connected to the gate lines and the data lines An LCD panel including a plurality of pixel parts; A data driver which applies a gray voltage according to image data to the plurality of data lines; And A gate driver sequentially applying scan signals to the plurality of gate lines Including; The pixel portion, A first transistor turned on by a scan signal applied through the gate line and transferring a gray voltage applied through the data line; A first capacitor generating a pixel voltage by charging a gray voltage transferred through the first transistor; Second and third transistors turned on by a scan signal applied through a front gate line to transfer second and third voltages; And A second capacitor generating an auxiliary voltage by charging a difference between the second and third voltages transmitted through the second and third transistors Liquid crystal display comprising a. delete delete According to claim 1, The data driver, And a gray voltage having different polarities to each pixel forming one pixel column. According to claim 1, The data driver, And a gray voltage having the same polarity to each pixel of one pixel column. The method according to claim 4 or 5, The source terminals of the second and third transistors are connected to a common electrode voltage terminal, a front end data line, or an auxiliary data line. delete The method of claim 1, And wherein the second voltage is a common voltage and the third voltage is a data voltage applied to a front end data line.

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