JPH0335290A - Method for driving active matrix liquid crystal display - Google Patents

Abstract

PURPOSE:To decrease the flickers in monochromatic images by changing the polarities of a video signal in one field period at every two vertical rows. CONSTITUTION:The polarities of the video signal for displaying images on a liquid crystal panel in the driving of the active matrix liquid crystal display disposed with color filters so as to be successively repeated are so inverted that the polarities of the video signal supplied in every two vertical rows of the liquid crystal elements are inverted and the polarities are also inverted in every field. The polarities of every field do not deviate and the brightnesses are averaged in this way and, therefore, the flickers are inconspicuous even when the video signals of a large area in primary colors are received.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving an active matrix liquid crystal display, and particularly to a method for driving an active matrix liquid crystal display using active elements such as thin film transistors (TPTs).

[Prior Art] An example of a conventional method for driving a liquid crystal display is shown in FIGS. 4(a) and 4(b). To simplify the explanation, the number of liquid crystal elements on the liquid crystal screen (1) is 4 in the vertical direction and 8 in the horizontal direction.
32 pieces in total. In this figure, the polarity of each element in the odd field and even field is represented by the ■ symbol as positive polarity, and the O symbol as negative polarity, and the filter color of each element is R (red), G (green), B. (blue).

Note that the source driver and gate driver are omitted in the figure.

Next, the operation will be explained. When driving a liquid crystal panel, if it is always driven with the same polarity, it will have a negative effect on the life of the liquid crystal, so in order to eliminate this negative effect, the
As shown in FIG. 4(b), the polarity of the video signal is inverted for each field and driven. However, T F T (
In a liquid crystal panel using a thin film transistor, (1) the potential of the pixel electrode changes due to the coupling of stray capacitance between the gate and drain of the TPT.

(2) Flicker occurs in the polarity reversal period of the video signal due to insufficient on-characteristics of the TPT.

There are other problems.

For this reason, as shown in Figures 4(a) and 4(b), by inverting the polarity of the video signal for each column and creating a difference in brightness for each column, it is possible to The large screen flicker of one field cycle was reduced.

As a result, as shown in Figures 5(a) and 5(b), when focusing on G (green) monochrome, the elements in the odd field are significantly positively applied, and the elements in the even field are applied negatively. was.

[Problem to be Solved by the Invention] The conventional method for driving a liquid crystal display is as described above, in which the polarity of the video signal is inverted for each column and also for each field, thereby eliminating flicker. However, in a color liquid crystal display with a three-primary color pixel array, there were problems to be solved such as noticeable flicker because the brightness level changes from field to field when receiving a monochromatic, large-area video signal.

The present invention was made in order to solve this problem, and an object of the present invention is to provide a method for driving an active matrix single-color display that can also reduce flicker in monochromatic images.

[Means for Solving the Problems] The method for driving an active matrix liquid crystal display according to the present invention is such that flicker is made inconspicuous even when a large area video signal is received in single primary colors such as R, G, and B. In addition, the polarity of the video signal supplied to every two vertical columns of liquid crystal elements is reversed, and the polarity is also reversed every field.

[Operation] In the method for driving an active matrix liquid crystal display according to the present invention, the polarity of the video signal supplied to every two vertical columns of liquid crystal elements is inverted, and the polarity is also inverted every field.

As a result, the polarity of each field is not biased and the brightness is averaged, so that flicker becomes less noticeable even when a large-area video signal in primary colors is received.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. In FIGS. 1(a) and 1(b), (1) is a liquid crystal screen, and the filter color of each pixel is represented by RSG' and B. Furthermore, the polarity of the video signal applied to the active element (not shown in the figure) of each pixel is represented by the symbol ``■'' for positive polarity and the symbol e for negative polarity.

Further, FIGS. 2(a) and 2(b) show a liquid crystal screen (1) when the liquid crystal display according to the method of this embodiment receives a G monochromatic signal.

Note that FIGS. 1(a) and 2(a) correspond to odd-numbered fields, and FIG. 1(b) and FIG. 2(b) correspond to even-numbered fields, respectively.

In addition, in the figure, in order to simplify the explanation, the number of liquid crystal elements is 32 in total, 4 in the vertical direction and 8 in the horizontal direction.

Next, the operation of this embodiment will be explained. Figure 1(a)
indicates the polarity of the video signal applied to the liquid crystal element of the liquid crystal panel during the odd field, and FIG. 1(b) indicates the polarity of the video signal applied to the liquid crystal element of the liquid crystal panel during the even field. In FIG. 1(a), the polarity of the video signal (2) shown in FIG. The pixel corresponding to 2 is positive, and the pixel corresponding to R or B in the second and sixth columns, and the pixel corresponding to 6 in the third and seventh columns is negative ○.

In addition, in FIG. 1(b), the polarity of the video signal (2) shown in FIG. Or, for the pixel corresponding to R, it is negative e, and for the pixel corresponding to R or B in the second and sixth columns, and the pixel corresponding to G in the third and seventh column, it is positive ■.

Figures 2(a) and 2(b) show the odd field (a) and even field (b) when only the G signal is received.
represents the polarity of the video signal.

As shown in Figure 1, since video signals with different polarities are applied to the liquid crystal elements in every two vertical columns, a difference in brightness occurs in each two vertical columns, but this is the equivalent of two pixels on the liquid crystal element, so it is extremely They are closely spaced. Therefore, at a normal viewing position, the difference in brightness and darkness is not detected by the display viewer 6 due to the integral effect of the eye. Furthermore, since the eight elements have different polarities for each field, there is no adverse effect on the life of the liquid crystal element.

Furthermore, as shown in Fig. 2, even when using a single G color, the polarity of the video signal of the entire liquid crystal element does not reverse for each field as in the conventional example shown in Fig. 5, and the positive and negative signals are distributed almost evenly. Because of the large screen, flickering does not occur.

Similarly, no flicker occurs on the large screen even when R and B are used alone.

As described above, according to this embodiment, the color filters are arranged in a repeating manner, and when driving an active matrix liquid crystal display, the polarity of the video signal for displaying an image on the liquid crystal panel is set in two vertical columns. By performing chemotaxis at one field period for each field, the positive and negative polarities of the screen of each field are almost evenly distributed even in monochromatic mode, and the image displayed on the screen has only a small amount of flicker.

[Effects of the Invention] As explained above, in this invention, when the polarity of the video signal applied to the liquid crystal element is switched every two vertical columns, the polarity is also reversed every field. There are effects such as no flicker even when the color is different, and there is no adverse effect on the -Li life of the liquid crystal element.

[Brief explanation of drawings]

FIG. 1(a) and FIG. 1(b) are respectively of the present invention.
An explanatory diagram of a liquid crystal screen with an odd field and an even field according to an embodiment, FIG. 2(a) and FIG. 2(b) respectively show an odd field showing a G monochromatic reception state of a liquid crystal screen according to an embodiment of the present invention. An explanatory diagram of and the number field,
The third plow is an explanatory diagram of video signal waveforms with different polarities, Figure 4 (
Figures 511 (a) and 4 (b) are clear diagrams of each odd field and even field of a conventional LCD screen, respectively.
) and FIG. 5(b) are explanatory diagrams of an odd field and an even field, respectively, showing the G monochrome reception state of a conventional liquid crystal screen. In the figure, (1) is a liquid crystal screen, (2) is a 1ETh video signal, and (3) is a negative polarity video signal. In the drawings, the same reference numerals indicate tj-1 or equivalent parts.

Claims (1)

[Claims] In driving an active matrix liquid crystal display in which color filters are arranged in a sequential manner,
A method for driving an active matrix liquid crystal display, characterized in that the polarity of a video signal for displaying an image on a liquid crystal panel is changed in one field period every two vertical columns.