KR20100007067A - Driving circuit for liquid crystal display device and method for driving the same - Google Patents

Abstract

PURPOSE: A driving circuit for a liquid crystal display device and a method for driving the same are provided to improve the brightness efficiency of an image by implementing a wide viewing angle and a narrow viewing angle selectively. CONSTITUTION: In a driving circuit for a liquid crystal display device and a method for driving the same, a liquid crystal panel(2) comprises quad type unit pixels consisting of an RGB sub pixel and an ECB(Electrical Controlled Birefringence) sub pixel. A drive controller operates gate lines and data line of the liquid crystal panel. A viewing angle controller(7) generates a selection control signal according to a viewing angle selection signal inputted from the outside. The viewing angle drive mode of the ECB sub pixel is converted.

Description

DRIVING CIRCUIT FOR LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR DRIVING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a device for driving a liquid crystal display and a driving method thereof to selectively implement a wide viewing angle and a narrow viewing angle, and to further improve brightness efficiency of an image when implementing a wide viewing angle. will be.

In general, a liquid crystal display device displays an image by injecting a liquid crystal between two substrates and applying an electric field to the liquid crystal through opposing electrodes with the liquid crystal interposed therebetween to adjust the light transmittance of the liquid crystal.

The liquid crystal display may be classified into a vertical electric field application type or a horizontal electric field application type liquid crystal display device according to the direction of the electric field for driving the liquid crystal.

The vertical field applying liquid crystal display device is a TN (Twist Namatic) mode in which a liquid crystal is driven by a vertical electric field between a pixel electrode and a common electrode which are disposed to face the upper and lower substrates, respectively. In the TN mode, since the common electrode of the upper substrate and the pixel electrode of the lower substrate forming the vertical electric field are both formed of transparent electrodes, a large aperture ratio can be ensured. However, since the liquid crystal is driven in the vertical direction by the vertical electric field, the movement angle of the liquid crystal affects the light traveling in the lateral direction, so that the viewing angle is narrowed to about 90 degrees.

The horizontal field application type liquid crystal display is an IPS (In Plane Switching) mode in which a liquid crystal is driven by a horizontal electric field between a pixel electrode and a common electrode arranged side by side on a lower substrate. In the IPS mode, since the liquid crystal is driven in the horizontal direction, since there is almost no movement in the vertical direction, the viewing angle is widened to about 160 degrees due to less influence on the light traveling in the lateral direction.

In the related art, liquid crystal cells formed in the liquid crystal panel of the liquid crystal display are generally formed in a stripe type. However, recently, a liquid crystal panel having a quad type cell structure including one ECB (Electric Controlled Birefringence) subpixel and three RGB subpixels in order to be able to arbitrarily switch between wide viewing angle mode and narrow viewing angle mode. The liquid crystal display device provided with this was developed.

As shown in FIG. 1, a quad type liquid crystal cell includes an R sub pixel, a G sub pixel, a B sub pixel, and an ECB sub pixel, wherein the R and G sub pixels are horizontally configured, and the ECB and B sub pixels are R and G sub pixels. It is constructed horizontally with the pixel.

R and ECB subpixels positioned perpendicular to each other are commonly connected to the first data line DL1, and G and B subpixels are commonly connected to the second data line DL2. In addition, the R and G sub pixels positioned horizontally to each other are commonly connected to the first gate line GL1, and the ECB sub pixel and the B sub pixel are commonly connected to the second gate line GL2.

Here, the ECB sub-pixels are used to adjust the wide viewing angle mode and the narrow viewing angle mode. In other words, each of the RGB sub-pixels is used to display the original image, and the ECB sub-pixels are used to display the interfering image so that the original image is not accurately seen in the lateral direction of the liquid crystal panel (eg, about 45 degrees from the front). Can be used.

Specifically, in the narrow viewing angle mode, the interference image is also displayed on each ECB subpixel while the original image is displayed on the RGB subpixels, so that the original image and the interference image are simultaneously displayed in the lateral direction. That is, only the original image is seen from the front of the liquid crystal panel and the interference image is not seen. However, when viewed from the side of the liquid crystal panel, the original image and the interference image are overlapped to realize the narrow viewing angle.

However, the conventional liquid crystal panel having a quad type cell structure has a problem that luminance is reduced by the area occupied by the ECB subpixels because the ECB subpixels do not transmit light in the wide viewing angle mode. In detail, since the area occupied by the ECB subpixels in the liquid crystal panel of the quad-type cell structure is 25%, the luminance is reduced by about 25% compared to the liquid crystal panel of the general RGB stripe structure, thereby decreasing the brightness efficiency.

The present invention has been made to solve the above problems, and the liquid crystal display device and the drive device to improve the brightness efficiency of the image by improving the brightness when implementing the wide viewing angle and narrow viewing angle selectively and wide viewing angle and The purpose is to provide the driving method.

According to an aspect of the present invention, there is provided a driving apparatus of a liquid crystal display device including: a liquid crystal panel including quad type unit pixels including R, G, B sub pixels, and ECB sub pixels; A driving controller driving the gate lines and the data lines of the liquid crystal panel; A viewing angle controller configured to generate a selection control signal according to a viewing angle selection signal input from the outside and convert the viewing angle driving mode of each ECB sub-pixel; And a viewing angle control line controller supplying a first common voltage or an image signal to the viewing angle control lines of the ECB sub-pixels according to the selection control signal.

The driving controller may be displayed through the ECB subpixels according to a data driver driving data lines of the liquid crystal panel, a gate driver driving gate lines of the liquid crystal panel, the viewing angle selection signal, and image data input from the outside. Generating a second common voltage including the first common voltage and a timing controller configured to generate the ECB data and to align the ECB data with the image data and supply the ECB data to the data driver; And a common voltage generator configured to supply the liquid crystal panel and the viewing angle control line controller, and supply or block the second common voltage to the ECB sub-pixel according to the viewing angle selection signal or the selection control signal.

The viewing angle control line controller is provided at an input terminal of odd-numbered data lines of the data lines to receive the image signal and the first common voltage, respectively, and a low level selection control signal is input from the viewing angle controller. And outputting the first common voltage to the viewing angle control line, and outputting the video signal to the viewing angle control line at a timing at which a high level selection control signal is input from the viewing angle controller.

When the first common voltage is input to the viewing angle control line, each of the ECB sub pixels forms a horizontal electric field according to the difference voltage between the image signal input to the pixel electrode and the first common voltage input to the lower common electrode. When the second common voltage is applied to the upper common electrode and the image signal is input to the viewing angle control line, the image signal simultaneously input to the pixel electrode and the lower common electrode and the second common voltage of the upper common electrode. The vertical electric field is formed in accordance with the difference voltage between and.

Each of the ECB sub-pixels has the same gate as that of the first TFT and the first TFT, which supplies an image signal from the data line to the pixel electrode in response to a scan pulse input from one of the gate lines. And a second TFT for supplying a first common voltage or an image signal from the viewing angle control line to the lower common electrode in response to a scan pulse of the line, whereby a first capacitor is formed between the pixel electrode and the upper common electrode. The second capacitor is formed between the pixel electrode and the lower common electrode, and the third capacitor is formed between the lower common electrode and the upper common electrode.

In addition, the driving method of the liquid crystal display according to the embodiment of the present invention for achieving the above object is a liquid crystal panel and a liquid crystal panel having a quad-type unit pixels consisting of R, G, B sub-pixels and ECB sub-pixels A driving method of a liquid crystal display device having a driving control unit for driving gate lines and data lines of a panel, the method comprising: generating a selection control signal according to a viewing angle selection signal input from an external device and controlling the viewing angle driving mode of each ECB sub-pixel; Converting; And supplying a first common voltage or an image signal to the viewing angle control lines of the respective ECB sub-pixels according to the selection control signal.

The driving method of the liquid crystal display includes driving data lines of the liquid crystal panel, driving gate lines of the liquid crystal panel, and through the ECB sub-pixels according to the viewing angle selection signal and image data input from the outside. Generating ECB data to be displayed; supplying the ECB data along with the image data to a data driver for aligning and outputting the data; generating a second common voltage including the first common voltage to generate the first common voltage; Supplying a voltage to the liquid crystal panel, supplying or blocking the second common voltage to the ECB sub-pixel according to the viewing angle selection signal or the selection control signal.

The supplying of the first common voltage or the image signal to the viewing angle control lines may include receiving the image signal and the first common voltage, respectively, according to the selection control signal having a low level. Outputting a common voltage to the viewing angle control line at a timing of inputting a common voltage to the viewing angle control line and inputting the selection control signal of a high level.

When the first common voltage is input to the viewing angle control line, each of the ECB sub pixels forms a horizontal electric field according to the difference voltage between the image signal input to the pixel electrode and the first common voltage input to the lower common electrode. When the second common voltage is applied to the upper common electrode and the image signal is input to the viewing angle control line, the image signal simultaneously input to the pixel electrode and the lower common electrode and the second common voltage of the upper common electrode. The vertical electric field is formed in accordance with the difference voltage between and.

Each of the ECB sub-pixels supplies an image signal from the data line to the pixel electrode according to a scan pulse input from one of the gate lines using a first TFT, and uses a second TFT. The first common voltage or the image signal from the viewing angle control line is supplied to the lower common electrode according to the scan pulse of the same gate line as the first TFT.

The driving device and the driving method of the liquid crystal display according to the exemplary embodiment of the present invention having the above characteristics have the following effects.

That is, the driving apparatus and driving method thereof of the liquid crystal display according to the present invention can improve the brightness efficiency of the image by driving the ECB sub-pixel in the same manner as the RGB sub-pixels in the wide viewing angle mode to improve the brightness of the image. . In addition, in the narrow viewing angle mode, unlike the RGB subpixels, the viewing angle may be reduced by driving the ECB subpixels to form a vertical electric field.

Hereinafter, a driving apparatus and a driving method thereof of a liquid crystal display according to an exemplary embodiment of the present invention having the above characteristics will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram illustrating a driving device of a liquid crystal display according to a first embodiment of the present invention.

The liquid crystal display shown in FIG. 2 includes a liquid crystal panel 2 having quad type unit pixels consisting of R, G, B sub pixels, and ECB sub pixels; A driving controller driving the gate lines GL1 to GLn and the data lines DL1 to DLm of the liquid crystal panel 2; A viewing angle controller (7) for generating a selection control signal (CS) according to a viewing angle selection signal (SES) input from the outside to switch the viewing angle driving mode of each ECB sub-pixel; And a viewing angle control line controller 9 for supplying a first common voltage Vcom1 or an image signal dV to the viewing angle control lines CL of the ECB subpixels according to the selection control signal CS. .

The driving control unit may include a data driver 4 for driving the data lines DL1 to DLm of the liquid crystal panel 2 and a gate driver 6 for driving the gate lines GL1 to GLn of the liquid crystal panel 2. And generating ECB data E to be displayed through each of the ECB sub-pixels according to the viewing angle selection signal SES and the image data RGB input from the outside, and generating the ECB data together with the image data RGB. The timing controller 8 and the first and second common voltages Vcom1 and Vcom2 are respectively generated by aligning E) to the data driver 4 and supplying the first common voltage Vcom1 to the liquid crystal panel. 2) and supplying or blocking the second common voltage Vcom2 to the ECB subpixel in accordance with the viewing angle selection signal SES or the selection control signal CS. The common voltage generator 5 is provided.

Here, the first common voltage Vcom1 may be a lower common electrode voltage supplied to the lower common electrode of the R, G, and B sub pixels and the ECB sub pixel, and the second common voltage Vcom2 may be a narrow viewing angle driving mode. The upper common electrode voltage supplied to the upper common electrode of the ECB sub-pixel may be used.

The liquid crystal panel 2 includes at least one thin film transistor TFT formed in each of the sub-pixels R, G, B, and ECB defined by the plurality of gate lines GL1 through GLn and the data lines DL1 through DLm. A film transistor (T1, T2) and a liquid crystal capacitor (Clc) connected to at least one of the TFTs (T1, T2).

The liquid crystal capacitor Clc of each of the subpixels R, G, and B includes a pixel electrode connected to the first TFT T1 and a lower common electrode formed by separating an insulating layer on the pixel electrode. A fringe field is formed in the pixel electrode. The first TFT T1 supplies the image signal dV from each data line DL1 to DLm to the pixel electrode in response to the scan pulses from the gate lines GL1 to GLn. The liquid crystal capacitor Clc charges the difference voltage between the image signal dV supplied to the pixel electrode and the first common voltage Vcom1 supplied to the lower common electrode, and varies the arrangement of the liquid crystal molecules according to the difference voltage. Gradation is realized by adjusting the transmittance. The storage capacitor Cst is connected to the liquid crystal capacitor Clc in parallel so that the image signal dV charged in the liquid crystal capacitor Clc is maintained until the next image signal dV is supplied.

The liquid crystal capacitor Clc of the ECB sub pixel is formed in a plate shape on a lower substrate, and includes a pixel electrode connected to the first TFT T1 and a lower common electrode formed by separating an insulating layer on the pixel electrode. And a fringe field is formed on the pixel electrode. In addition, the liquid crystal capacitor Clc of the ECB sub-pixel may be formed such that the pixel electrode and the lower common electrode face vertically with the upper common electrode provided in the form of a plate on the upper substrate and the liquid crystal interposed therebetween. The lower common electrode receives the first common voltage Vcom1 or the image signal dV from the viewing angle control line CL through the second TFT T2. Accordingly, the ECB sub-pixel is provided with the first common voltage Vcom1 or the image signal dV input to the lower common electrode through the viewing angle control line CL, and the second common voltage Vcom2 that can be supplied to the upper common electrode. The viewing angle is adjusted by driving the liquid crystal horizontally or vertically. Such a liquid crystal panel 2 of the present invention will be described in more detail later with reference to the accompanying drawings.

The data driver 4 uses the source start pulse SSP, the source shift clock SSC, and the like among the data control signals DCS from the timing controller 8 to align the image data RGBE with the timing controller 8. Is converted into an analog voltage, that is, a video signal. Specifically, the data driver 4 latches the image data RGBE input according to the source shift clock SSC among the data control signals DCS, and then, in response to the source output enable SOE signal, each gate line The video signal dV for one horizontal line is supplied to each of the data lines DL1 to DLm every one horizontal period in which the scan pulses are supplied to the GL1 to GLn. At this time, the data driver 4 selects a positive or negative gamma voltage having a predetermined level according to the grayscale value of the input image data RGBE, and converts the selected gamma voltage into the image signal dV for each data line DL1. To DLm).

The gate driver 6 sequentially generates scan pulses in response to the gate control signal GCS from the timing controller 8, for example, the gate start pulse GSP and the gate shift clock GSC, and enables the gate output. The pulse width of the scan pulses is controlled according to the (GOE) signal. In addition, the scan pulses whose pulse width is controlled, that is, the gate-on voltages are sequentially supplied to the gate lines GL1 to GLn. Specifically, the gate driver 6 shifts the gate start pulse GSP from the timing controller 8 in accordance with the gate shift clock GSC to sequentially generate scan pulses. The pulse width of the scan pulses is controlled according to the gate output enable signal (GOE) to sequentially supply the gate-on voltages of which the pulse width is controlled to the gate lines GL1 to GLn. On the other hand, the gate-off voltage is supplied to the gate lines GL1 to GLn during the period when the gate-on voltage is not supplied.

The timing controller 8 generates the ECB data E using the image data RGB input from the outside according to the viewing angle control signal SES input from the user. In detail, when the viewing angle control signal SES is inputted so that the liquid crystal panel 2 operates in the wide viewing angle mode, the timing controller 8 may increase the luminance of the image data RGB displayed through the unit pixels. E) is generated. Here, the ECB data E may be generated to correspond to the average, maximum, or minimum gray value of the image data RGB. If the viewing angle control signal SES is input so that the liquid crystal panel 2 operates in the narrow viewing angle mode, the timing controller 8 outputs ECB data E which is set in advance such that the ECB sub-pixels display an interference image or the like. do. As such, the timing controller 8 may output the ECB data E so that the liquid crystal panel 2 displays the interference image according to the viewing angle control signal SES, and the ECB data so that the luminance of the image data RGB increases. (E) is also output.

In this way, the timing controller 8 generates the ECB data E, supplies the ECB data E to the data driver 4 together with the input image data RGB, and inputs an external synchronization signal DCLK. Generate gate and data control signals (GCS, DCS) using, Hsync, Vsync, and DE. Each of the generated gate and data control signals GCS and DCS is supplied to the data and gate drivers 4 and 6.

The viewing angle control unit 7 receives a viewing angle control signal SES from the outside together with the timing controller 8. In addition, at least one of gate and data control signals GCS and DCS output from the timing controller 8 is further supplied. When the viewing angle control signal SES is inputted so that the liquid crystal panel 2 operates in the wide viewing angle mode, the viewing angle control unit 7 generates a selection control signal CS having a low level to generate the viewing angle control line controller 9. Supplies). However, when the viewing angle control signal SES is input so that the liquid crystal panel 2 operates in the narrow viewing angle mode, the viewing angle control unit 7 uses the received at least one gate and data control signal GCS or DCS. The timing at which the video signal dV is input to the ECB subpixel is captured. The high level selection control signal CS is supplied to the viewing angle control line control unit 9 so as to be synchronized with the timing at which the image signal dV is input to each ECB sub-pixel. On the other hand, when the viewing angle control signal SES is input to operate in the narrow viewing angle mode, the viewing angle controller 7 may supply it to the common voltage generator 5 again. Then, the common voltage generator 5 supplies the second common voltage Vcom2 to the upper common electrode of each ECB subpixel according to the viewing angle control signal SES of the narrow viewing angle mode.

The viewing angle control line controller 9 is formed to correspond to data lines connected to the ECB sub-pixels, for example, odd-numbered data lines DL1,..., DLm-1, as shown in FIG. 2. The viewing angle control line controller 9 is provided at the input terminals of the odd-numbered data lines DL1,..., DLm-1, and the image signal dV from the data driver 4 and the common voltage generator 5. Each of the first common voltages Vcom1 from When the low level selection control signal CS is input from the viewing angle controller 7, the first common voltage Vcom1 is output to the viewing angle control line CL. However, the viewing angle control line controller 9 receives the image signal dV from the data driver 4 at the timing at which the high level selection control signal CS is input from the viewing angle controller 7. ) Of course, the image signals dV from the data driver 4 are supplied to each of the data lines DL1 to DLm.

When the first common voltage Vcom1 is input to the viewing angle control line CL through the above-described process, the ECB subpixels include the image signal dV input to the pixel electrode and the first common voltage input to the lower common electrode. A fringe field is formed according to the difference voltage of Vcom) to display an image. However, when the second common voltage Vcom2 is applied to the upper common electrode and the image signal dV is input to the viewing angle control line CL, the image signal dV input to the pixel electrode and the lower common electrode are input. Since the image signal dV is the same, the liquid crystal is driven vertically according to the difference voltage with the second common voltage Vcom2 input to the upper common electrode to display the image in ECB mode.

3 is a plan view schematically illustrating a unit pixel of the liquid crystal panel illustrated in FIG. 2, and FIG. 4 is an equivalent circuit diagram of the ECB subpixel and the B subpixel of FIG. 3. 5 is a cross-sectional view illustrating the ECB subpixels and the B subpixels of FIG. 3.

The unit pixel of the quad type shown in FIGS. 3 to 5 shows a unit pixel when the liquid crystal panel 2 is made of amorphous silicon (a-Si) panel. Specifically, the unit pixels of the liquid crystal panel 2 are composed of red, green, and blue, i.e., R, G, and B subpixels R, G, and B, and ECB subpixels ECB for viewing angle control. In each unit pixel, an R sub pixel R and a G sub pixel G are formed in a horizontal direction. The ECB sub-pixel ECB is formed in the diagonal direction of the G sub-pixel G, and is adjacent to the R sub-pixel R in the vertical direction, and is formed in the horizontal direction with the B sub-pixel B. FIG.

Referring to FIG. 4, the ECB sub-pixel ECB includes a first TFT that supplies an image signal dV from the data line DL1 to the pixel electrode in response to a scan pulse from one of the gate lines GLn. A first common voltage Vcom1 or an image signal dV from the viewing angle control line CL to the lower common electrode in response to a scan pulse of the same gate line as T1 and the first TFT T1; 2 TFT (T2) is provided.

Accordingly, the first capacitor C1 is formed between the pixel electrode and the upper common electrode of the ECB sub-pixel ECB, and the second capacitor C2 is formed between the pixel electrode and the lower common electrode, and the lower common electrode and the upper common electrode. The third capacitor C3 is formed between the common electrodes. Here, the second common voltage Vcom2 is supplied to the upper common electrode of the ECB sub-pixel ECB from the common voltage generator 5 through the upper common line which is not shown in the narrow viewing angle driving mode.

4 and 5, the liquid crystal panel 2 includes a lower substrate 10 for controlling the amount of light transmitted to the upper substrate 20 by controlling the alignment of the liquid crystal layer 30.

Each unit pixel of the lower substrate 10 forms a horizontal electric field to form the horizontal or vertical electric field with R, G, and B sub-pixels R, G and B that control the alignment of the liquid crystal layer 30. An ECB sub-pixel ECB which controls the orientation of 30 in the horizontal or vertical direction. Here, the R, G, and B sub pixels R, G, and B are formed of an FFS structure forming a fringe field, and the ECB sub pixels, ECB, are formed of a mixture of an ECB structure and an FFS structure according to a driving mode. do.

As described above, the ECB sub-pixel ECB includes the image signal dV applied to the lower common electrode 17 and the pixel electrode 16 and the second common voltage Vcom2 applied to the upper common electrode 22. According to the difference voltage, a vertical electric field is formed. In addition, the second common voltage Vcom2 of the upper common electrode 22 is cut off, the image signal dV is supplied to the pixel electrode 16, and the first common voltage Vcom is applied to the lower common electrode 17. When applied, a horizontal electric field is formed by the difference voltage between the image signal dV and the first common voltage Vcom.

In the B sub-pixel B of FIG. 4, the first TFT T1 is positioned at the intersection of the n-th gate line GLn and the second data line DL2, and the pixel line is connected to the first TFT T1. Is arranged in a direction parallel to the n-th gate line GLn. The pixel electrodes 16 may be connected to the pixel line to form a plate in parallel with each of the data lines DL1 to DLn. The lower common electrode 17 is formed with a plurality of slit structures with the pixel electrodes 16 and the insulating layer 18 interposed therebetween. The lower common electrode 17 may be connected to each other through a common line parallel to each of the gate lines GL1 to GLn, and is formed on the entire surface of the lower substrate 10 to form an ECB sub-pixel (ECB) region. The lower common electrodes 16 of the R, G, and B subpixels R, G, and B may be electrically connected to each other. That is, each of the R, G, and B sub pixels R, G, and B forms a fringe field by the lower common electrode 17 and the pixel electrode 16.

In the present invention, only the configuration in which the pixel electrode 16 is formed on the lower substrate 10 and the lower common electrode 17 is formed on the pixel electrode 16 with the insulating layer 18 therebetween has been described. The formation position and configuration of the pixel 17 and the pixel electrode 16 can be configured because they form a fringe field even if they are interchanged. Therefore, only the configuration in which the lower common electrode 17 is formed on the pixel electrode 16 with the insulating layer 18 therebetween will be described.

As described above, the R, G, and B sub pixels R, G, and B may be implemented in various forms within the range of a structure forming the fringe field. For example, the lower common electrodes 17 formed in a shape having a plurality of slits may be configured in a straight line parallel to each other, or bent at least once to form a multi-domain in which the alignment directions of the liquid crystals are different therebetween. You may. In particular, when each sub-pixel has a bent structure, response speed, color shift, and the like are improved, thereby improving image quality. On the other hand, each of the R, G, and B sub pixels R, G, and B is red, green, and blue as the blue color filter 23 is formed in the region of the upper substrate 20 facing the B sub pixel B. Color filters are formed on the upper substrate 20, respectively.

In the ECB sub-pixel ECB, the first TFT T1 is disposed at the intersection of any one of the gate line GLn and the first data line DL1, and the pixel electrode 16 is disposed in the first TFT T1. Connected. The pixel electrodes 16 are connected to the pixel lines and formed in a plate shape in parallel with the data lines DL1 to DLm. The lower common electrode 17 is formed to have a plurality of slits with the pixel electrodes 16 and the insulating layer 18 therebetween. The lower common electrode 17 is connected to each other through a common line (not shown) parallel to each of the gate lines GL1 to GLn. As such, the configuration of the pixel electrodes 16 and the lower common electrode 17 of the ECB sub-pixel ECB may be configured to form a fringe field in the same manner as the R, G, and B sub-pixels R, G, and B. Can be. In the ECB sub-pixel ECB, the upper common electrode 22 faces the lower common electrode 17 on the upper substrate 20 facing the pixel electrode 16. The second common voltage Vcom2 is applied to the upper common electrode 22 according to a wide or narrow viewing angle driving mode to control the viewing angle while forming a vertical electric field with the pixel electrode 16 and the lower common electrode 17. .

As described above, the ECB sub-pixel ECB receives the difference voltage between the image signal dV applied to the pixel electrode 16 and the second common voltage Vcom2 supplied to the upper common electrode in the narrow viewing angle mode. A first capacitor C1 is configured which holds until dV) is supplied. In addition, in the ECB sub-pixel ECB, the first common voltage Vcom1 and the pixel electrode 16 input from the viewing angle control line controller 9 to the lower common electrode 17 through the viewing angle control line CL in the wide viewing angle mode. The second capacitor C2 is configured to maintain the difference voltage with the video signal dV applied as a) until the next video signal dV is supplied. Here, the second capacitor C2 is a capacitor for improving the brightness of the image by transmitting light in the wide viewing angle mode. In addition, the ECB sub-pixel ECB is supplied to the image signal dV and the upper common electrode input to the lower common electrode 17 through the viewing angle control line CL from the viewing angle control line controller 9 in the narrow viewing angle mode. The third capacitor C1 is configured to maintain the difference voltage with the second common voltage Vcom2 until the next image signal dV is supplied. More specifically, the potential of the pixel electrode 16 and the potential of the lower common electrode 17 are coupled to the same signal when the image signal dV is supplied to the lower common electrode 17 through the viewing angle control line CL. Therefore, the potential is also the same. Accordingly, when the second common voltage Vcom2 is applied to the upper common electrode 22 when the potential of the pixel electrode 16 is equal to the potential of the lower common electrode 17, the ECB sub-pixel ECB is a vertical electric field. Will form.

The driving method of the liquid crystal display device having the above-described configuration is as follows.

First, when the user intends to drive the liquid crystal panel 2 in the wide viewing angle mode, the viewing angle controller 7 generates a low level selection control signal CS according to the viewing angle control signal SES set to the wide viewing angle mode. . The generated selection control signal CS is supplied to the viewing angle control line controller 9. Then, the viewing angle control line controller 9 outputs the first common voltage Vcom1 from the common voltage generator 5 to the viewing angle control line CL.

At this time, the first TFT T1 of the ECB sub-pixel supplies the image signal dV from the data lines DL1 to DLm to the pixel electrode 16 in response to an input scan pulse. In addition, the first common voltage Vcom1 from the viewing angle control line CL is supplied to the lower common electrode 17 in response to the scan pulse input like the first TFT T1. Then, the second capacitor C is charged with the difference voltage between the image signal dV and the first common voltage Vcom1 to horizontally drive the liquid crystal, thereby transmitting light capable of increasing the brightness of the image.

On the other hand, when the user intends to drive the liquid crystal panel 2 in the narrow viewing angle mode, the viewing angle controller generates a high level selection control signal CS according to the viewing angle control signal SES set to the narrow viewing angle mode. The generated selection control signal CS is supplied to the viewing angle control line controller 9. Then, the viewing angle control line controller 9 outputs the image signal dV from the odd-numbered corresponding data line (for example, DL1, DL3, ..., or DLm-1) to the viewing angle control line CL. In addition, the common voltage generator 5 also supplies the second common voltage Vcom2 to the upper common electrode 22 of the ECB subpixel according to the viewing angle control signal SES or the selection control signal CS.

At this time, the first TFT T1 of the ECB sub-pixel supplies the image signal dV from the data lines DL1 to DLm to the pixel electrode 16 in response to an input scan pulse. In addition, the image signal dV from the viewing angle control line CL is supplied to the lower common electrode 17 in response to the scan pulse input together with the first TFT T1. Then, since the difference voltage between the image signal dV and the second common voltage Vcom2 is charged in the first and third capacitors C1 and C3 to drive the liquid crystal vertically, an interference image according to the image signal dV is displayed. Done.

As described above, the liquid crystal of the ECB sub-pixel ECB in the narrow viewing angle mode is tilted by a vertical electric field formed between the lower common electrode 17 and the pixel electrode 16 and the upper common electrode 22. The user cannot observe the light, but light leakage occurs in the left and right viewing angles. As described above, since the liquid crystal in the ECB sub-pixel ECB is not twisted but only tilted, the light in front of the ECB sub-pixel ECB cannot be observed in the white state or the black state. However, light leaks can be observed in the left and right viewing angle directions. When the user observes the liquid crystal panel 2 from the left and right viewing angles from the viewpoint of four sub-pixels forming one unit pixel, As a result, the black luminance rises rapidly, resulting in a drop in the contrast ratio CR. Therefore, the viewing angle in the left and right viewing angle directions can be reduced.

As described above, the driving device and the driving method thereof of the liquid crystal display according to the exemplary embodiment of the present invention are performed in the same way as the RGB subpixels R, G, and B in the wide viewing angle mode. By driving to improve the brightness of the image can improve the brightness efficiency of the image. In addition, in the narrow viewing angle mode, unlike the RGB subpixels, the viewing angle may be reduced by driving the ECB subpixels ECB to form a vertical electric field.

The liquid crystal display of the present invention has the advantage that the additional manufacturing cost is low and relatively simple in terms of the process by forming the upper common electrode 22 only on the upper substrate 20 of the ECB sub-pixel (ECB). In addition, the upper common electrode 22 added to the upper substrate 20 may float in the wide viewing angle mode or allow the same voltage as the lower common electrode 17 to flow, and in the narrow viewing angle mode, the lower common electrode 17 may have a constant voltage. It is very easy in terms of driving by driving to have a car.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

1 is a configuration diagram showing a conventional quad type liquid crystal cell.

2 is a block diagram illustrating a driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a plan view schematically illustrating a unit pixel of the liquid crystal panel illustrated in FIG. 2.

FIG. 4 is an equivalent circuit diagram of the ECB subpixel and B subpixel of FIG. 3 in more detail. FIG.

5 is a cross-sectional view illustrating an ECB sub pixel and a B sub pixel of FIG. 3;

<Brief description of symbols for the main parts of the drawings>

2: liquid crystal panel 4: data driver

5 common voltage generator 6 gate driver

7: viewing angle control unit 8: timing controller

9: viewing angle control line control unit 10: lower substrate

16 pixel electrode 17 lower common electrode

18: insulating film 22: upper common electrode

Claims (10)

A liquid crystal panel including quad type unit pixels including R, G, and B sub pixels and ECB sub pixels; A driving controller driving the gate lines and the data lines of the liquid crystal panel; A viewing angle controller configured to generate a selection control signal according to a viewing angle selection signal input from the outside and convert the viewing angle driving mode of each ECB sub-pixel; And And a viewing angle control line control unit for supplying a first common voltage or an image signal to the viewing angle control lines of each of the ECB sub-pixels according to the selection control signal. The method of claim 1, The driving control unit A data driver for driving data lines of the liquid crystal panel; A gate driver for driving gate lines of the liquid crystal panel; A timing controller which generates ECB data to be displayed through the ECB sub-pixels according to the viewing angle selection signal and image data input from the outside, and arranges the ECB data together with the image data to supply the data driver; Generating a second common voltage including the first common voltage, respectively, and supplying the first common voltage to the liquid crystal panel and the viewing angle control line controller, and according to the viewing angle selection signal or the selection control signal. And a common voltage generator for supplying or blocking a voltage to the ECB sub-pixel. The method of claim 2, The viewing angle control line control unit It is provided at the input terminal of the odd-numbered data lines of the data lines to receive the image signal and the first common voltage, respectively, When the selection control signal having a low level is input from the viewing angle controller, the first common voltage is output to the viewing angle control line. When the selection control signal having a high level is input from the viewing angle controller, the image signal is output. A drive device for a liquid crystal display device, characterized in that output to a viewing angle control line. The method of claim 3, wherein Each of the ECB sub pixels When the first common voltage is input to the viewing angle control line, a horizontal electric field is formed according to the difference voltage between the image signal input to the pixel electrode and the first common voltage input to the lower common electrode. When the second common voltage is applied to the upper common electrode and the image signal is input to the viewing angle control line, the image signal simultaneously input to the pixel electrode and the lower common electrode and the second common voltage of the upper common electrode A drive device for a liquid crystal display, characterized in that a vertical electric field is formed in accordance with the difference voltage. The method of claim 4, wherein Each of the ECB sub pixels A first TFT supplying an image signal from the data line to the pixel electrode in response to a scan pulse input from one of the gate lines; and And a second TFT for supplying a first common voltage or an image signal from the viewing angle control line to the lower common electrode in response to a scan pulse of the same gate line as the first TFT, thereby providing the pixel electrode and the upper common electrode. And a second capacitor formed between the pixel electrode and the lower common electrode, and a third capacitor formed between the lower common electrode and the upper common electrode. A liquid crystal display device comprising: a liquid crystal panel having quad type unit pixels including R, G, B sub pixels, and ECB sub pixels; and a driving control unit for driving gate lines and data lines of the liquid crystal panel. , Generating a selection control signal according to a viewing angle selection signal input from the outside to change the viewing angle driving mode of each ECB sub-pixel; And And supplying a first common voltage or an image signal to the viewing angle control lines of each of the ECB sub-pixels according to the selection control signal. The method of claim 6, The driving method of the liquid crystal display device is Driving data lines of the liquid crystal panel; Driving gate lines of the liquid crystal panel; Generating ECB data to be displayed through the ECB subpixels according to the viewing angle selection signal and image data input from the outside; Supplying the ECB data along with the image data to a data driver for sorting and outputting the image data; Generating a second common voltage including the first common voltage, respectively, and supplying the first common voltage to the liquid crystal panel; and And supplying or blocking the second common voltage to the ECB sub-pixel in accordance with the viewing angle selection signal or the selection control signal. The method of claim 7, wherein Supplying the first common voltage or the image signal to the viewing angle control lines Receiving the video signal and the first common voltage, respectively; Outputting the first common voltage to the viewing angle control line according to the selection control signal at a low level, and And outputting the image signal to the viewing angle control line at a timing at which the selection control signal of a high level is input. The method of claim 8, Each of the ECB sub pixels When the first common voltage is input to the viewing angle control line, a horizontal electric field is formed according to the difference voltage between the image signal input to the pixel electrode and the first common voltage input to the lower common electrode. When the second common voltage is applied to the upper common electrode and the image signal is input to the viewing angle control line, the image signal simultaneously input to the pixel electrode and the lower common electrode and the second common voltage of the upper common electrode A vertical electric field is formed according to the difference voltage of the liquid crystal display device. The method of claim 9, Each of the ECB sub pixels Supplying an image signal from the data line to the pixel electrode according to a scan pulse input from one of the gate lines using a first TFT, And a first common voltage or an image signal from the viewing angle control line is supplied to the lower common electrode according to the scan pulse of the same gate line as the first TFT using a second TFT. .

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