Method of driving liquid crystal display device

Abstract

A method of driving a liquid crystal display device includes supplying data voltages to a pixel on a moving path of an image during a scroll operation, wherein the data voltages displaying the image have opposite polarities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 is a block diagram of a LCD device according to the related art;

FIG. 2 is a circuit diagram of a liquid crystal panel of FIG. 1;

FIG. 3 is a view illustrating a scroll after-image in the LCD device according to the related art;

FIG. 4 is a table of data voltages causing a DC voltage accumulation when a static image is scrolled with a predetermined scroll pattern in an LCD device according to the related art;

FIG. 5 is a table of data voltages when a static image is scrolled with a predetermined scroll pattern in an LCD device according to an embodiment of the present invention; and

FIGS. 6A and 6B are flow charts illustrating a method of driving an LCD device according to the embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to illustrated embodiments of the present invention, which are illustrated in the accompanying drawings.

FIG. 5 is a table of data voltages when a static image is scrolled with a predetermined scroll pattern in an LCD device according to an embodiment of the present invention.

An LCD device according to the embodiment of the present invention is similar to the LCD device of FIGS. 1 and 2. Accordingly, explanations of parts similar to parts of FIGS. 1 and 2 will be omitted for brevity's sake.

Referring to FIG. 5, a static image is white, and a background of the static image is gray. The predetermined scroll pattern is that when the static image is scrolled, the static image moves in a speed of M pixel/frame, for example, 8 pixel/frame and a white data voltage is inputted to a pixel, which is located on a moving path, every N frames according to the speed, for example, 8 frames.

During a non-scroll operation, an inversion method, such as a one-dot inversion method and first and second two-dot inversion methods, is conducted in all frames of the non-scroll operation. During a scroll operation, all frames of the scroll operation may be divided in a plurality of time sections, and the inversion method may be conducted in each time section. The time section may be an input period of the white data voltage i.e., N frames. For example, when N is even, an inversion method in a time section may be opposite to an inversion method in a next time section, and thus polarity patterns of the pixel between adjacent time sections may be opposite. In other words, the pixel may have positive and negative polarities according to the inversion method in each time section, and the polarity patterns of data voltages may be opposite every time section. For example, when N is 8 and a one-dot inversion method is conducted, the LCD device is operated in the one-dot inversion method in each time section of 8 frames, and the polarity patterns of the data voltages are opposite every time section. Accordingly, the white data voltages having the opposite polarities are alternately inputted to the pixel every 8 frames. In other words, the white data voltages having a negative polarity are inputted at 8^th, 24^th, . . . frames, and the white data voltages having a positive polarity are inputted at 16^th, 32^nd, . . . frames. Accordingly, a DC component of the same polarity is not be accumulated in the pixel even as the predetermined scroll pattern continues, and thus an after-image due to the scroll operation can be prevented.

When N is odd, the LCD device may continue to be operated in the inversion method of the non-scroll operation without a change to the one-dot inversion method depending upon the time section.

FIGS. 6A and 6B are flow charts illustrating a method of driving an LCD device according to the embodiment of the present invention.

Referring to FIG. 6A, in order that a scroll operation of a static image, for example, a white static image, is conducted in the LCD device of the embodiment, the LCD device is supplied with an information associated with a moving speed (pixel/frame) of the static image from an external system, for example, a computer or TV system (st1). The moving speed may be even.

The information associated with moving speed may be inputted to a timing controller. The timing controller may change an inversion method to control polarities of data voltages to prevent a DC voltage accumulation (st2).

In more detail, referring to FIG. 6B, the timing controller may set an input period of a white data voltage based on the moving speed. For example, the input period is N frames. The timing controller may change an inversion method of the LCD device according to the input period. For example, when an inversion method is operated before the scroll operation and N is even, the inversion method may be conducted separately in each time section. The time section may be the input period. For a first time section of 1 to Nth frames, data voltages with a first polarity pattern are inputted to a pixel on a moving path of a static image (st2-1). For a second time section of (N+1)^th+2N^th frames, data voltages with a second polarity pattern which is opposite to the first polarity pattern (st2-2) are inputted to the pixel. For example, referring to FIG. 5 where N is 8 and a one-dot inversion method is conducted, positive (+) and negative (−) polarities are alternately inputted to the pixel for 1^st to 8^th frames, and negative (−) and positive (+) polarities are alternately inputted to the pixel for 9^th to 16^th frames. Accordingly, white data voltages having opposite polarities are alternately supplied to the pixel every N frames, and thus an after-image can be prevented.

As described above, in the embodiment, the data voltages displaying the static image do not have the same polarity but have opposite polarities during the scroll operation. Therefore, a DC voltage is not accumulated in the pixel on the moving path of the static image, and an after-image can be prevented.

The embodiment can be applicable to other inversion methods.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method of driving a liquid crystal display device, the method comprising:supplying data voltages to a pixel on a moving path of an image during a scroll operation, wherein the data voltages displaying the image periodically have opposite polarities.

2. The method of claim 1, wherein the data voltages displaying the image are supplied every N frames.

3. The method of claim 2, wherein the data voltages displaying the image alternately have opposite polarities every N frames.

4. The method of claim 3, wherein N is even.

5. The method of claim 3, wherein a first polarity pattern of the data voltages during N frames is opposite to a second polarity pattern of the data voltages during next N frames.

6. The method of claim 4, wherein each of the first and second polarity patterns is an alternate pattern of opposite polarities every at least a frame.

7. A method of driving a liquid crystal display device, the method comprising: supplying first data voltages to a pixel on a moving path of an image during N frames of a scroll operation; andsupplying second data voltages to the pixel during next N frames of the scroll operation,wherein the first data voltage of a last frame of the N frames and the second data voltage of a last frame of the next N frames display the image and have opposite polarities.

8. The method of claim 7, wherein N is even.

9. The method of claim 7, wherein a first polarity pattern of the first data voltages is opposite to a second polarity pattern of the second data voltages.

10. The method of claim 8, wherein each of the first and second polarity patterns is an alternate pattern of opposite polarities every at least a frame.

11. A method of driving a liquid crystal display device, the method comprising: supplying data voltages to a pixel on a moving path of an image during a scroll operation, wherein the data voltages displaying the image have opposite polarities every N frames and N is even.

12. The method of claim 11, wherein a first polarity pattern of the data voltages during N frames is opposite to a second polarity pattern of the data voltages during next N frames.

13. The method of claim 12, wherein each of the first and second polarity patterns is an alternate pattern of opposite polarities every at least a frame.