KR20100064567A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to reduce coupling which is generated in lines of the liquid crystal panel by shifting a common voltage signal by a frame unit and supplying it to the common electrode. CONSTITUTION: A liquid crystal display comprises a liquid crystal panel and a common voltage supply unit. The common voltage supply unit supplies the common voltage signal to a common electrode of the liquid crystal panel. The common voltage signal is reversed by a period of more than two lines. The common voltage signal is shifted into one line by a frame unit.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device.

The liquid crystal display adjusts the light transmittance of the liquid crystal according to the video data to display an image corresponding to the video data. Such a liquid crystal display device can increase the size of the screen beyond the limit while reducing the thickness. In addition, the liquid crystal display device can be made slimmer and lighter.

In order to display an image corresponding to video data, the liquid crystal display includes drive circuits for driving the liquid crystal panel. The liquid crystal panel includes liquid crystal cells arranged in a matrix form. Each of the liquid crystal cells responds to a pixel drive signal from the drive circuit. Each of these liquid crystal cells orientates liquid crystal molecules in a direction corresponding to a potential difference between a pixel driving signal and a common voltage serving as a reference voltage. The amount of light passing through the liquid crystal cell is adjusted in accordance with the alignment direction of the liquid crystal molecules, so that an image is displayed.

The present invention provides a liquid crystal display device capable of improving the image quality of a display image.

Liquid crystal display device according to an embodiment of the present invention; And a common voltage supply unit configured to supply a common voltage signal inverted to a common electrode of the liquid crystal panel by using two or more lines, and the common voltage signal is shifted by one line in units of frames.

Another liquid crystal display according to an embodiment of the present invention is a liquid crystal panel; A data driver for supplying a data signal to the liquid crystal panel; And a common voltage supply unit configured to supply a common voltage signal inverted to a common electrode of the liquid crystal panel by giving at least two lines, wherein a potential difference between the common voltage signal and the data signal is referenced to any one line of the liquid crystal panel. The polarity is reversed every two or more frames.

According to the present invention, a common voltage signal which is inverted at regular intervals for line inversion driving is shifted in units of frames and supplied to the common electrode of the liquid crystal panel, thereby reducing the difference in coupling phenomenon occurring in each of the lines of the liquid crystal panel. It is possible to reduce, thus reducing the evenness between the lines to improve the image quality of the display image.

Hereinafter, a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a schematic configuration of a liquid crystal display, and the illustrated liquid crystal display includes a liquid crystal panel 100, a data driver 200, a gate driver 300, a timing controller 400, and a common voltage supply unit. 500 may be included.

Referring to FIG. 1, a liquid crystal display device includes a gate driver 300 connected to a plurality of gate lines GL1 to GLn on the liquid crystal panel 100 and a plurality of data lines DL1 to DLm on the liquid crystal panel 100. The data driver 200 may be connected.

The plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLm are formed on the liquid crystal panel 100 so as to cross each other so that the plurality of pixel areas are separated. Liquid crystal pixels are formed in each of the plurality of pixel regions. Each of the liquid crystal pixels includes a thin film transistor MT and a liquid crystal cell CLC connected in series between a corresponding data line DL and a common voltage line Vcom.

The thin film transistor MT switches the data signal to be supplied to the corresponding liquid crystal cell CLC from the corresponding data line DL in response to the scan signal Vgs on the corresponding gate line GL. Each time the corresponding thin film transistor MT is turned on (ie, every frame period), the liquid crystal cell CLC charges the data signal from the corresponding data line DL.

The liquid crystal cell CLC may maintain the voltage of the charged data signal Vds until the corresponding thin film transistor MT is turned on again by the gate signal on the corresponding gate line GL. By the data signal charged in the liquid crystal cell CLC, the liquid crystal molecules included in the liquid crystal cell CLC are supplied to the common electrode of the liquid crystal panel 100 through the charged data signal and the common voltage line Vcom. The amount of light passing through the liquid crystal cell CLC may be adjusted in the direction corresponding to the potential difference between the two electrodes.

In this manner, the liquid crystal panel 100 can display an image by the liquid crystal cell CLC that adjusts the light transmission amount according to the potential difference between the data signal and the common voltage signal.

The gate driver 300 sequentially enables the plurality of gate lines GL1 to GLn for one frame by a predetermined period (for example, one horizontal synchronization signal). To this end, the gate driver 300 may generate a plurality of scan signals Vgs having exclusively enable pulses which are sequentially shifted for each period of the horizontal synchronization signal.

The data driver 200 corresponds to the number of data lines DL1 to DLm each time one of the plurality of gate lines GL1 to GLn is enabled (ie, corresponds to the number of pixels arranged in one gate line). Data signals). Each of the data signals for one line is supplied to a corresponding pixel (ie, a liquid crystal cell) on the liquid crystal panel 100 via the corresponding data line DL. Each of the pixels arranged on the gate line GL may pass an amount of light corresponding to a voltage level of the data signal.

In order to generate one line of data signals, the data driver 200 sequentially inputs one line of pixel data LVDs for each period of the enable pulse included in the scan signal Vgs. The data driver 200 may simultaneously convert the sequentially input pixel data LVDs into analog data signals using the gamma voltage set. The gamma voltages may determine the voltage difference between the gray levels of the data signal and the swing width of the data signal.

The gate driver 300 and the data driver 200 are controlled by the timing controller 400. The timing controller 400 receives the synchronization signals SYNC from a graphic controller (a device for supplying a video data source and a power source) which is not shown. The sync signals SYNC supplied from an external video data source include a data enable signal DEN, a data clock Dclk, a horizontal sync signal Hsync, a vertical sync signal Vsync, and the like. The timing controller 400 uses the synchronization signals SYNC to allow the gate driver 300 to sequentially scan a plurality of gate lines GL1 to GLn on the liquid crystal panel 10 every frame ( Generates gate control signals GCS necessary to generate Vgs). The gate control signals GCS include a gate start pulse GSP and a gate clock GSC.

In addition, the timing controller 400 causes the data driver 200 to sequentially input pixel data of one line for each period in which the gate line GL is enabled, and sequentially input the pixel data of one line inputted in analog form. To generate and output data control signals (DCS) necessary to convert and output the data signal. In addition, the timing controller 400 may receive the pixel data streams FVDs divided in frame units (one image unit) from an external system (not shown). The timing controller 400 divides the pixel data streams FVDs in units of frames into the pixel data LVDs for each line and supplies them to the data driver 200.

In addition, the liquid crystal display may receive an input voltage Vin from a graphic controller (not shown) and generate a common voltage signal Vcom to provide a common electrode formed on the liquid crystal panel 100, more specifically, the liquid crystal panel 100. It may include a common voltage supply unit 500 for supplying.

The common voltage signal Vcom and the data signal Vds for each frame, line, or pixel are prevented in order to prevent deterioration or flicker caused by an electric field in one direction applied to the liquid crystal cells CLC for a long time. ), The polarity of the potential difference can be reversed.

In the liquid crystal display according to the exemplary embodiment of the present invention, the common voltage signal Vcom supplied to the common electrode of the liquid crystal panel 100 is inverted in units of lines so that the potential between the common voltage signal Vcom and the data signal Vds is increased. The polarity of the difference can be reversed.

For example, the timing controller 400 may supply a polarity inversion signal POL to the common voltage supply unit 500 to control inversion of the common voltage signal Vcom output from the common voltage supply unit 500. .

2 to 5 illustrate embodiments of the above-described line inversion driving method, and briefly illustrate only some pixel regions of the liquid crystal panel 100.

Referring to FIG. 2, a common voltage signal Vcom and data for each line are included in a liquid crystal cell CLC defined by a plurality of data lines DL1 through DL9 and a plurality of gate lines GL1 through GL2 that cross each other. The polarity of the potential difference between the signals Vds can be reversed.

That is, in the first line L1, the potential difference Vd between the common voltage signal Vcom and the data signal Vds has a positive polarity, and in the second line L2, the potential difference Vd has a negative polarity. Thus, the polarity of the potential difference Vd in each line can be reversed in one line period.

In the liquid crystal display according to the exemplary embodiment of the present invention, the polarity of the potential difference Vd in each line of the liquid crystal panel 100 may be inverted at intervals of two or more lines.

For example, as shown in FIG. 3, in the first and second lines L1 and L2, the potential difference Vd between the common voltage signal Vcom and the data signal Vds has a positive polarity. In the four lines L3 and 4, the potential difference Vd has a negative polarity, and the polarity of the potential difference Vd in each line may be reversed in two line periods.

FIG. 4 illustrates an embodiment of a method of inverting a common voltage signal Vcom supplied to a common electrode of the liquid crystal panel 100. FIGS. 4A and 4B illustrate continuous first and second operations. The waveforms of the common voltage signal Vcom supplied from the frame are shown.

Referring to FIG. 4A, the common voltage signal Vcom is inverted every two lines in the first frame, and as shown in FIG. 3, the potential between the common voltage signal Vcom and the data signal Vds. The difference Vd can be inverted in two line periods. In this case, the period T of the common voltage signal supplied from the common voltage supply unit 500 to the common electrode of the liquid crystal panel 100 may be a time required to drive four lines of the liquid crystal panel 100.

Referring to FIG. 4B, in the second frame, the polarity of the potential difference Vd in each line may be reversed to the opposite polarity as in the first frame, which is the previous frame. That is, the polarity of the potential difference Vd in each line may be reversed every frame.

For example, the first and second lines L1 and L2 having the positive potential difference Vd in the first frame have the negative potential difference Vd in the second frame and the negative potential in the first frame. The third and fourth lines L3 and L4 having the potential difference Vd may have a positive potential difference Vd in the second frame.

By the inversion driving method as described above, the liquid crystal panel 100 having the polarity of the potential difference Vd as shown in FIG. 3 in the first frame is shown in FIG. 5 in the second frame following the first frame. It can be reversed to have the polarity of the potential difference Vd as shown.

As described above, when the common voltage signal Vcom is inverted for the inversion driving of a line unit, a coupling phenomenon may occur in each line by toggling of the common voltage signal Vcom. .

In addition, the coupling phenomenon occurring in two adjacent lines may be different from each other, and thus a difference in gray scales displayed in the two lines may occur, thereby degrading image quality such as a horizontal line pattern in a display image.

For example, as shown in FIG. 4, the common voltage signal Vcom continuously changes in front of the first line L1 of the first and second lines L1 and L2 having the same polarity of the potential difference Vd. The common voltage signal Vcom is continuously maintained in front of the second line L2. Accordingly, different coupling phenomena may occur in the first and second lines L1 and L2, and thus gray levels displayed in the first and second lines L1 and L2 may be different from each other.

In the liquid crystal display according to the exemplary embodiment of the present invention, the common voltage signal Vcom is inverted every two or more lines so that the coupling phenomenon as described above occurs uniformly in the lines of the liquid crystal panel 100. Can be shifted frame by frame.

FIG. 6 illustrates a first embodiment of the inversion driving method according to the present invention, and FIGS. 5A, 5B, 5C, and 4D are continuous first, second, third, and fourth embodiments. The waveforms of the common voltage signal Vcom supplied from the frame are shown.

Referring to FIG. 6A, the common voltage signal Vcom is inverted every two lines in the first frame, and the potential difference Vd between the common voltage signal Vcom and the data signal Vds is cycled by two lines. Can be reversed.

Referring to FIG. 6B, in the second frame, the common voltage signal Vcom supplied in the first frame illustrated in FIG. 6A is shifted by one line to the common electrode of the liquid crystal panel 100. Supply.

As illustrated in FIG. 6C, in the third frame, the common voltage signal Vcom supplied in the second frame illustrated in FIG. 6B is shifted by one line and supplied.

In addition, as illustrated in (d) of FIG. 6, in the fourth frame, the common voltage signal Vcom supplied in the third frame illustrated in (c) of FIG. 6 is shifted by one line and supplied.

That is, the common voltage signal Vcom may be shifted by one line every frame and supplied to the common electrode of the liquid crystal panel 100.

The shift of the common voltage signal Vcom by one line may mean that the common voltage signal Vcom is shifted by the time required to drive one line of the liquid crystal panel 100.

Also, for example, when the period of the common voltage signal Vcom is T, the common voltage signal Vcom is shifted by a time corresponding to T / 4 every frame, thereby common to the liquid crystal panel 100. Can be supplied to the electrode.

As described above, by shifting the common voltage signal Vcom in units of frames, the polarity of the potential difference Vd in each of the lines L1 to L10 is not inverted every frame but is inverted at a predetermined number of frames. Can be.

That is, the polarity of the potential difference Vd in the first line L1 may be inverted every two frames, and the polarity of the potential difference Vd may be inverted every two frames in each of the other lines.

As shown in FIG. 6, when the common voltage signal Vcom is shifted by one line every frame, the coupling phenomenon occurring in each of the lines L1 to L10 becomes uniform when averaged over time. Accordingly, the gray level difference between the lines L1 to L10 is reduced, and the image quality of the display image can be improved.

FIG. 7 illustrates a second embodiment of the inversion driving method according to the present invention, and illustrates a case in which the common voltage signal Vcom is inverted every three lines. 7A to 7F respectively illustrate waveforms of the common voltage signal Vcom supplied in six consecutive frames.

Referring to FIGS. 7A to 7F, in each frame, the common voltage signal Vcom is inverted every three lines, and the potential difference Vd between the common voltage signal Vcom and the data signal Vds is set to three. Lines can be inverted periodically.

In addition, the common voltage signal Vcom, which is inverted every three lines, may be shifted by one line every frame and supplied to the common electrode of the liquid crystal panel 100.

That is, the common voltage signal Vcom may be shifted by the time required to drive one line of the liquid crystal panel 100 every frame, for example, when the period of the common voltage signal Vcom is T. The common voltage signal Vcom may be shifted by a time corresponding to T / 6 every frame and supplied to the common electrode of the liquid crystal panel 100.

In addition, as shown in FIG. 7, the polarity of the potential difference Vd in each line may be inverted every three frames.

Also in the second embodiment, the coupling phenomenon occurring in each of the lines L1 to L10 becomes uniform when averaged over time, so that the gradation difference between the lines L1 to L10 may be reduced.

The inversion driving method according to the exemplary embodiment of the present invention as described above with reference to FIGS. 6 and 7 may be applicable to the case where the common voltage signal Vcom is inverted every four or more lines.

For example, assuming that the common voltage signal Vcom having a period T is inverted by n lines, the common voltage signal Vcom may be shifted by one line every frame, and in time, T every frame. It may be shifted by / 2n and supplied to the common electrode of the liquid crystal panel 100.

In this case, based on each line of the liquid crystal panel 100, the potential difference Vd between the common voltage signal Vcom and the data signal Vds may be reversed in polarity every n frames.

Although described above with reference to the embodiment is only an example and is not intended to limit the invention, those of ordinary skill in the art to which the present invention does not exemplify the above within the scope not departing from the essential characteristics of this embodiment It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a block diagram schematically showing the configuration of a liquid crystal display.

2 to 5 illustrate embodiments of the inversion driving method.

6 and 7 illustrate embodiments of the inversion driving method according to the present invention.

Claims (7)

Liquid crystal panels; And A common voltage supply unit supplying a common voltage signal inverted by giving at least two lines to the common electrode of the liquid crystal panel, The common voltage signal is shifted by one line in a frame unit. The method of claim 1, And when the common voltage signal having a period T is inverted by n lines, the common voltage signal is shifted by a time corresponding to T / 2n every frame. The method of claim 1, And a potential difference between the common voltage signal and a data signal supplied to the liquid crystal panel is inverted in polarity every two or more lines. The method of claim 3, And a potential difference between the common voltage signal and the data signal is reversed in polarity every two or more frames with respect to any one line of the liquid crystal panel. Liquid crystal panels; A data driver for supplying a data signal to the liquid crystal panel; And A common voltage supply unit supplying a common voltage signal inverted by giving at least two lines to the common electrode of the liquid crystal panel, And a potential difference between the common voltage signal and the data signal is reversed in polarity every two or more frames with respect to any one line of the liquid crystal panel. The method of claim 5, The common voltage signal is shifted by one line in frame units. The method of claim 5, And the potential difference of any one line of the liquid crystal panel is inverted in polarity every n frames when the common voltage signal is inverted every n lines.

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