Patent Grant
8199102
This application claims priority to Korean Patent application No. 10-2007-0048755, filed on May 18, 2007 and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which are herein incorporated by reference in their entirety.
1. Field of the Invention
The present invention relates to a liquid crystal display and a method of driving the same, and more particularly, to a liquid crystal display having a PenTile pixel arrangement and a method of driving the same.
2. Description of the Related Art
In a PenTile pixel arrangement, blue pixels are shared to display two dots. The blue pixels that are adjacent to one another are driven by different gate driving circuits. This PenTile pixel arrangement is used to achieve high resolution with a reduced number of data driving circuits. Further, a PenTile RGBW scheme, wherein a white (W) pixel as well as red (R), green (G) and blue (B) pixels is used, has been proposed to implement a liquid crystal display capable of providing an image of higher quality at high resolution.
Since the data driving circuit for a liquid crystal display is mounted in the form of a chip on a liquid crystal display panel, it cannot readily cope with a change in the resolution of the liquid crystal display panel. To solve this problem, a line selection unit is provided between the data driving circuit and the liquid crystal display panel. The line selection unit delivers a data signal supplied from one channel of the data driving circuit to the plurality of data lines at different time intervals. When pixels on a row selected by a gate driving signal supplied from a gate driving circuit are turned on, and the data signal from the data driving circuit is sequentially supplied to a plurality of pixels through the line selection unit at the time intervals, an image is displayed.
However, if such a driving manner is applied to the liquid crystal display having the PenTile RGBW pixel arrangement, a vertical stripe defect is generated at a specific pixel array due to coupling between a data line and an adjacent pixel.
The present invention, according to one aspect thereof, provides a liquid crystal display and a method of driving the same, wherein the vertical stripe defect generated by coupling between a data line and an adjacent pixel is prevented.
According to an aspect of the present invention, a liquid crystal display, includes: a liquid crystal display panel having a plurality of gate lines and a plurality of data lines formed on a substrate to cross each other, and a plurality of pixels respectively connected to the plurality of gate lines and the plurality of data lines; a data driving unit for outputting data signals through a plurality of channel terminals; and a line selection unit for applying the data signals to alternately arranged first and second data line blocks, each of the data line blocks having a plurality of the data lines, wherein the first data line blocks include the data lines arranged adjacent to one side of the corresponding pixels and second data line blocks include the data lines arranged to the other side of the corresponding pixels. The line selection unit may include a plurality of switching units, each of the switching units applying the data signal from each channel terminal to the data line block connected to the channel terminal.
Each switching unit may sequentially apply the data signal output through each channel terminal to the plurality of data lines in the data line block.
The pixels may include red, green, blue and white pixels.
The red, green, blue and white pixels may be sequentially arranged in a gate line extending direction, and two of the red, green, blue and white pixels may be alternately arranged in a data line extending direction.
The red, green, blue and white pixels may be sequentially arranged in a gate line extending direction, and the same color pixels may not be successively arranged in the gate line extending direction and a data line extending direction.
The data signal may be sequentially applied to the plurality of data lines in the first data line block along a first direction, and the data signal may be sequentially applied to the plurality of data lines in the second data line block along a second direction opposite to the first direction.
The first direction may be a gate line extending direction. The respective data lines in the first data line blocks may be arranged adjacent to the right side of the corresponding pixels, and the respective data lines in the second data line blocks may be arranged adjacent to the left side of the corresponding pixels.
The second direction may be a gate line extending direction.
The respective data lines in the first data line blocks may be arranged adjacent to the left side of the corresponding pixels, and the respective data lines in the second data line blocks may be arranged adjacent to the right side of the corresponding pixels.
The first data line block may include an even number of data lines, and the second data line block may include an even number of data lines.
The data driving unit may output the data signal with a changed polarity.
The data driving unit may use an N×1 inversion manner in which the polarity of the data signal is inverted every N-th gate line, where N is a natural number.
The display may further include a signal control unit for outputting a selection control signal for controlling the line selection unit.
Each switching unit may include a plurality of switching devices driven by the selection control signal.
According to another aspect of the present invention, there is provided a method of driving a liquid crystal display, including: outputting data signals through a plurality of channel terminals; and applying the data signals output through the respective channel terminals to first data line blocks and second data line blocks, wherein the data signal is sequentially applied to the plurality of data lines in the first data line block along a first direction, and the data signal is sequentially applied to the plurality of data lines in the second data line block along a second direction opposite to the first direction.
The data lines in the first data line blocks may be arranged adjacent to one side of the corresponding pixels, and the data lines in the second data line blocks may be arranged adjacent to the other side of the corresponding pixels, the first and second data line blocks being alternately arranged.
Outputting data signals may include outputting the data signals with an inverted polarity every N-th gate line, where N is a natural number.
Preferred embodiments of the present invention can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to
The liquid crystal display panel 100 includes a plurality of gate lines G1 to Gn extending in one direction, e.g., in a row direction, and a plurality of data lines D1 to Dm extending in a direction perpendicular thereto, e.g., in a column direction. The liquid crystal display panel 100 further includes pixel areas, which are provided at intersections of the gate lines G1 to Gn and the data lines D1 to Dm. Each pixel area is formed with a pixel PX having a thin film transistor T, a storage capacitor Cst, and a liquid crystal capacitor Clc. The liquid crystal display panel 100 includes a thin film transistor substrate 110 having the thin film transistors T, the gate lines G1 to Gn, the data lines D1 to Dm and pixel electrodes 115; a color filter substrate 120 having a black matrix, color filters 126 and a common electrode 125; and a liquid crystal 130 interposed between the thin film transistor substrate 110 and the color filter substrate 120.
Each thin film transistor T includes gate, source, and drain electrodes. The gate electrodes are connected to the gate lines G1 to Gn, the source electrodes are connected to the data lines D1 to Dm, and the drain electrodes are connected to the pixel electrodes 115. In response to a gate signal applied to a corresponding one of the gate lines G1 to Gn, the thin film transistor T supplies a data signal supplied through a corresponding one of the data lines D1 to Dm to the pixel electrode to change an electric field between both ends of the liquid crystal capacitor Clc. This changes an arrangement of the liquid crystal 130 to adjust transmissivity of light supplied from a backlight (not shown).
The gate driving unit 200, the data driving unit 300, the line selection unit 400, the signal control unit 500 and the driving-voltage generating unit 600 provide a plurality of signals for driving the liquid crystal display panel 100. The gate driving unit 200 may be formed directly on the liquid crystal display panel 100. The data driving unit 300 may be mounted on the liquid crystal display panel 100. Alternatively, the data driving unit 300 may be mounted on an additional printed circuit board (PCB) and then electrically connected to the liquid crystal display panel 100 through a flexible printed circuit (FPC) board. The line selection unit 400 may be mounted on the liquid crystal display panel 100, and the signal control unit 500 and the driving-voltage generating unit 600 may be mounted on a printed circuit board, and then electrically connected to the liquid crystal display panel 100 through a flexible printed circuit board.
The signal control unit 500 receives image signals, i.e., pixel data R, G, B and W, and control signals, such as a horizontal synchronization signal Hsync, a vertical synchronization signal Vsync, a main clock CLK, a data enable signal DE and the like from an external graphic controller (not shown). The signal control unit 500 processes the pixel data R, G, B, and W according to an operation condition of the liquid crystal display panel 100 to generate a gate control signal CON1, a data control signal CON2, and a selection control signal CON3, and sends the signals to the gate driving unit 200, the data driving unit 300, and the line selection unit 400, respectively. Here, the gate control signal CON1 includes a vertical synchronization start signal for instructing a start of output of the gate turn-on voltage Von, a gate clock signal for controlling a timing to output the gate turn-on voltage Von, an output enable signal for controlling the duration of the gate turn-on voltage Von, and the like. Further, the data control signal CON2 includes a horizontal synchronization start signal for indicating a transmission start of the pixel data, a load signal for instructing to apply a data voltage to the corresponding data line, an inversion signal for inverting the polarity of a gradation voltage relative to a common voltage, a data clock signal, and the like. The selection control signal CON3 includes a plurality of selection control signals CON31 to CON34 (see
The driving-voltage generating unit 600 generates a variety of driving voltages required for driving the liquid crystal display device by using external power input from an external power supply. The driving-voltage generating unit 600 generates a reference voltage AVDD, the gate turn-on voltage Von, a gate turn-off voltage Voff, and the common voltage. In response to a control signal from the signal control unit 500, the driving-voltage generating unit 600 applies the gate turn-on voltage Von and the gate turn-off voltage Voff to the gate driving unit 200 and applies the reference voltage AVDD to the data driving unit 300. Here, the reference voltage AVDD is used as reference voltage for generating the gradation voltage to drive the liquid crystal.
The gate driving unit 200 applies the gate turn on/off voltage Von/Voff from the driving-voltage generating unit 600 to the gate lines G1 to Gn in response the gate control signal CON1 from the signal control unit 500. Accordingly, the thin film transistors T can be controlled so that the gradation voltage is applied to the pixel.
The data driving unit 300 generates the gradation voltage using the data control signal CON2 from the signal control unit 500 and the reference voltage AVDD from the driving-voltage generating unit 600, and then applies the gradation voltage to channel terminals CH1 to CHk.
The line selection unit 400 is mounted on the liquid crystal display panel 100 to connect the channel terminals CH1 to CHk of the data driving unit 300 to the plurality of data lines D1 to Dm. In response to the selection control signal CON3 output from the signal control unit 500, the line selection unit 400 supplies the data signal from the data driving unit 300 to the plurality of data lines through the channel terminals CH1 to CHk. The data signal is sequentially supplied to the plurality of data lines connected to a channel terminal.
Referring to
The plurality of pixels include red (R), green (G), blue (B) and white (W) pixels. In this embodiment, the red (R), green (G), blue (B) and white (W) pixels are sequentially arranged on each odd-numbered row, and the blue (B), white (W), red (R) and green (G) pixels are sequentially arranged on each even-numbered row. As a result, the red (R) and blue (B) pixels are alternately arranged on the odd-numbered columns, and the green (G) and white (W) pixels are alternately arranged on the even-numbered columns. In the PenTile RGBW pixel arrangement, the red (R), green (G), blue (B) and white (W) pixels may be arranged in any of several manners other than the manner discussed in this embodiment. For example, the red (R), green (G), blue (B) and white (W) pixels may be arranged so that the same color pixels are not successively arranged in the row and column directions.
The plurality of data lines D1 to Dm are grouped into data line blocks DB1(1), DB2(1), . . . , DB1(j) and DB2(j), each of which includes a plurality of the data lines, e.g., four of the data lines. Each channel terminal is connected to the corresponding data line block including the four data lines through the line selection unit 400. The data line blocks include the first data line blocks DB1(1) to DB1(j) and the second data line blocks DB2(1) to DB2(j), wherein the first data line blocks DB1(1) to DB1(j) and the second data line blocks DB2(1) to DB2(j) are alternately arranged.
The data lines included in each of the first data line blocks DB1(1) to DB1(j) are arranged adjacent to the right side of the corresponding pixels, and the data lines included in each of the second data line blocks DB2(1) to DB2(j) are arranged adjacent to the left side of the corresponding pixels. That is, the data lines D1 to D4 included in the first data line block DB1(1) are arranged adjacent to the right side of the corresponding pixels, and the data lines D5 to D8 included in the second data line block DB2(1) are arranged at the left side of and adjacent to the corresponding pixels. As a result, the fourth data line D4 and the fifth data line D5 are arranged adjacent to each other and thus have no pixels arranged therebetween, and the eighth data line D8 and the ninth data line D9 are spaced apart from each other and thus have two pixels arranged to face each other therebetween.
Switching units SW1, SW3, . . . , SWi−1 connected to the first data line blocks DB1(1) to DB1(j) sequentially apply data signals output through the channel terminals CH1, CH3, . . . , CHk-1 to the plurality of data lines, and switching units SW2, SW4, . . . , SWi connected to the second data line blocks DB2(1) to DB2(j) sequentially apply data signals output through the channel terminals CH2, CH4, . . . , CHk to the plurality of data lines. At this time, the order in which the data signal is applied to the plurality of data lines in the first data line block is reverse to that in which the data signal is applied to the plurality of data lines in the second data line block. That is, the data signal is sequentially applied to the plurality of data lines in the first data line blocks in the gate line extending direction, i.e., from the left to the right, and the data signal is sequentially applied to the plurality of data lines in the second data line blocks in the opposite direction to the gate line extending direction, i.e., from the right to the left.
The configuration and operation of the line selection unit 400 will be described with reference to
In this embodiment, each of the switching units SW1 to SWi includes four switching devices, as the switching unit SWi, for example, includes SWi(1) to SWi(4), for connecting the channel CHk and the four data lines. Here, the switching device may be a transistor, but the present invention is not limited thereto. The switching device may be any of other devices having a switching function.
The first switching devices SW1(1) to SWi−1(1) in the switching units connected to the first data line blocks and the fourth switching devices SW2(4) to SWi(4) in the switching units connected to the second data line blocks are driven by the first selection control signal CON3(1). And the second switching devices SW1(2) to SWi−1(2) in the switching units connected to the first data line blocks and the third switching devices SW2(3) to SWi(3) in the switching units connected to the second data line blocks are driven by the second selection control signal CON3(2). Further, the third switching devices SW1(3) to SWi−1(3) in the switching units connected to the first data line blocks DB1(1) to DB1(j) and the second switching devices SW2(2) to SWi(2) in the switching units connected to the second data line blocks DB2(1) to DB2(j) are driven by the third selection control signal CON3(3). And the fourth switching devices SW1(4) to SWi−1(4) in the switching units connected to the first data line blocks and the first switching devices SW2(1) to SWi(1) in the switching units connected to the second data line blocks are driven by the fourth selection control signal CON3(4).
The selection control signal CON3 is input in the form of a pulse in order of the first selection control signal CON3(1), the second selection control signal CON3(2), the third selection control signal CON3(3) and the fourth selection control signal CON3(4), as shown in
A method of driving the liquid crystal display according to the embodiment of the present invention will be described with reference to
In response to the data control signal CON2, the data driving unit 300 sequentially receives image data corresponding to pixels on one row, selects a gradation voltage corresponding to each image data to convert the image data into a data signal, and supplies the data signal through the channel terminals CH1 to CHk. The gate driving unit 200 applies the gate on voltage Von to the gate lines G1 to Gn and thus turns on the thin film transistors connected to the gate lines G1 to Gn.
The gate on voltage Von is applied to the first gate line G1, so that the thin film transistors connected to the first gate line G1 are turned on. When data signals are applied through the odd-numbered channel terminals CH1, CH3, . . . , CHk-1, the first, second, third and fourth switching devices SW1(1) to SW1(4) in the switching unit SW1 connected to the first data line block DB1(1) are driven in this order. As a result, the data signals are applied to the data lines in order of the first, second, third and fourth data lines D1 to D4, so that the data signals are supplied to the pixels in order of the red (R), green (G), blue (B) and white (W) pixels on the odd-numbered row of the first data line block. Further, when data signals are applied through the even-numbered channel terminals CH2, CH4, . . . , CHk, the fourth, third, second and first switching devices SW2(4) to SW2(1) in the switching unit SW2 connected to the second data line block DB2(1) are driven in this order. As a result, the data signals are applied to the data lines in order of the eighth, seventh, sixth and fifth data lines D8 to D5, so that the data signals are supplied to the pixels in order of the white (W), blue (B), green (G) and red (R) pixels on the odd-numbered row of the second data line block.
The first to fourth data lines D1 to D4 included in the first data line block DB1(1) are arranged adjacent to the right side of the corresponding pixels, and the fifth to eighth data lines D5 to D8 in the second data line block DB2(2) are arranged adjacent to the left side of the corresponding pixels.
Accordingly, the data signal is applied through the first data line block DB1(1) to the second data line D2 after the red (R) pixel connected to the first data line D1 is charged. Since the second data line D2 is spaced apart from the charged red (R) pixel at least as much as the size of a unit pixel (e.g., d in
Further, the data signal is applied to the seventh data line D7 after the while (W) pixel connected to the eighth data line D8 is charged. Since the seventh data line D7 is spaced apart from the charged white (W) pixel at least as much as the size of a unit pixel (e.g., d in
According to the liquid crystal display of the embodiment of the present invention, when the data signals are sequentially applied to the first data line block and the second data line block through the respective channel terminals, the previously charged pixel is not substantially coupled with the data signal applied to the next data line. As a result, each pixel can substantially maintain its charged voltage unchanged, so that a vertical stripe defect is prevented from being generated at specific pixels.
Although the liquid crystal display according to the embodiment of the present invention may be driven by a dot inversion manner in which data signals having an inverted polarity are applied to adjacent pixels in order to prevent deterioration of the liquid crystal, the present invention is not limited thereto. The liquid crystal display may be driven in a column inversion manner, or in an N×1 inversion manner in which a polarity is inverted every N-th gate line (where, N is a natural number). That is, the liquid crystal display may be driven in a 2×1 or 3×1 inversion manner.
Referring to
The switching units SW1, SW3, . . . , SWi−1 connected to the first data line blocks DB1(1) to DB1(j) sequentially apply data signals output through the channel terminals CH1, CH3, . . . , CHk-1 to the plurality of data lines, and the switching units SW2, SW4, . . . , SWi connected to the second data line blocks DB2(1) to DB2(j) sequentially apply data signals output through the channel terminals CH2, CH4, . . . , CHk to the plurality of data lines. At this time, the data signal is sequentially applied to the plurality of data lines in the first data line blocks in the opposite direction to the gate line extending direction, i.e., from the right to the left, and the data signal is sequentially applied to the plurality of data lines in the second data line blocks in the gate line extending direction, i.e., from the left to the right.
In addition, the first switching devices SW1(1) to SWi(1) in the switching units of the line selection unit 400 are driven by the first selection control signal CON3(1), the second switching devices SW1(2) to SWi(2) are driven by the second selection control signal CON3(2), the third switching devices SW1(3) to SWi(3) are driven by the third selection control signal CON3(3), and the fourth switching devices SW1(4) to Swi(4) are driven by the fourth selection control signal CON3(4). The selection control signal CON3, the first selection control signal CON3(1), the second selection control signal CON3(2), the third selection control signal CON3(3) and the fourth selection control signal CON3(4) are input into the line selection unit in the form of a pulse as shown in
The even-numbered switching units SW2, SW4, . . . , SWi connected to the second data line blocks DB2(1) to DB2(j), the first, second, third and fourth switching devices are driven in this order, so that the data signals are applied to the data lines in order of the fifth, sixth, seventh and eighth data lines D5 to D8. As a result, the data signals are supplied to the pixels in order of the red (R), green (G), blue (B) and white (W) pixels on the odd-numbered row of the second data line blocks.
As described above, according to the embodiments of the present invention, when the data signals are applied to the first and second data line blocks through the respective channel terminals, the previously charged pixel is not substantially coupled with the data signal applied to the next data line. As a result, the charged voltage can be kept unchanged and a vertical stripe defect can be prevented from being generated at specific pixels. In addition, the display quality of the liquid crystal display can be improved by a simple modification of the structure. The above descriptions are merely exemplary embodiments of a liquid crystal display and a method of driving the same according to the present invention, so that the present invention is not limited thereto. The true scope of the present invention should be defined to the extent that those skilled in the art can make various modifications and changes thereto without departing from the scope of the invention, as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0048755 | May 2007 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6456350 | Ashizawa et al. | Sep 2002 | B1 |
| 6552706 | Ikeda et al. | Apr 2003 | B1 |
| 6731262 | Hector et al. | May 2004 | B2 |
| 7505017 | Yeo et al. | Mar 2009 | B1 |
| 7728810 | You et al. | Jun 2010 | B2 |
| 20030090614 | Kim et al. | May 2003 | A1 |
| 20040222961 | Lin et al. | Nov 2004 | A1 |
| 20050083341 | Higgins et al. | Apr 2005 | A1 |
| 20060044292 | Shen et al. | Mar 2006 | A1 |
| 20060061605 | Credelle | Mar 2006 | A1 |
| 20080180369 | Chiu et al. | Jul 2008 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20080284758 A1 | Nov 2008 | US |
