JPS5936486A - Driving system of matrix display panel - Google Patents

Abstract

PURPOSE:To improve the display contrast of liquid crystal, by providing a period giving a pause to a display in the vicinity of a vertical blanking period and keeping a potential difference between a data line and a timing line to zero at the pause period. CONSTITUTION:A drive circuit of the data line consists of voltage selecting circuits 10-16. The voltage selecting circuits 10-12 are circuits to invert the polarity with a frame signal fL and the voltage selecting circuits 13-14 are circuits to bring the data line to the same level as the non-selecting level of the timing line during the pause period with a pause period signal fD. Further, the voltage selecting circuits 15-16 are circuits inputting the drive output to the data line according to a display data input Di and n-set of blocks 17 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a matrix display panel.

What is a matrix display panel? The poles are arranged in a matrix in both the X and Y directions and are used to display characters, graphs, or images. For example, in the case of a liquid crystal display, display is performed using (NXM) pixels formed by N data lines and M timing lines. At this time, multiplex driving is normally used in which one timing line is selected and data is written and driven from the data line to the pixels in that column, and the period during which data corresponding to one pixel is applied is a total of 17M. This is usually called duty.

Generally, in the case of image or graphic display, timing line 1
00 is necessary.

Figure 1 shows the drive electrode arrangement of the liquid crystal IJ sock panel. Data lines 81 to Sn forming the drive electrodes are arranged, and timings mC1 to Om (rLXr
n) pixels.

FIG. 2 shows an example of the drive waveform for the panel in FIG. 1, with timing lines 01, 02 . Since the scan is performed as ``Ofn'', the death stay will be 1/m according to the regular timing line. In the case of image display, gradation is required, and gradation can be achieved by varying the driving pulse width W1 applied to the data line as shown in FIG. The problem when displaying television images using the raster scan method using such a drive system and panel is that in the case of a normal television signal, there are 525 scanning lines corresponding to the timing lines in one frame, and an odd number of scan lines. Since the field and even field are constructed by interlacing 5 lines of 262° each, if the image is displayed as is, it will be 1/262°5.
The reason is that a duty drive is required. Also, if the resolution is reduced to half, it will be necessary to drive at a duty of 1/131.25. However, with this driving duty, it is currently difficult to obtain sufficient contrast with liquid crystals. Therefore, by some means isometrically lowering the driving death of the liquid crystal and improving the display contrast,
It needs to be displayed in an easy-to-read format.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for driving a liquid crystal matrix panel in which the contrast can be improved.

According to the present invention, the voltage is not applied to the liquid crystal element during the period before and after the vertical erasing period in which no information is included in the video signal.
The contrast is improved by increasing the effective value ratio of F.

To explain the present invention in more detail, we will proceed based on a commonly used NTSO video signal as an example. Figure 3 shows the signal system, where signal (a) is the vertical synchronizing signal VS, (b) is the horizontal synchronizing signal H-8, (c) is an enlarged view of it, and (d) is the video signal V, S. It represents. Also, Fig. 4 shows the horizontal synchronization signal in Fig. 3 in an easy-to-understand manner, and the time of one field is 1/60 second, or 16.667 m5ec, and within this field there are 262.5 scanning lines. It is included. In the case of an IJ sock panel, it is possible to recognize an image even with half the number of scan f#s, that is, 131 lines, so for example, 2 scan lines
If one line is thinned out and displayed in a book, the drive becomes equivalent to 1/131 duty, but in reality, the image information is 26
It is sufficient to display 200 to 220 lines out of 2.5, and in fact, the time equivalent to 40 to 60 lines, including the remaining vertical blanking period, often does not contain any information signals. Therefore, for example, 24040 from the 20th in diagram @4
Image display is performed only in the inspection section, 1 to 19.241 to 2
If the period up to 62.5 is a rest period, the number of timing lines on the panel will be 220. However, the line selection period of the timing line remains at 1/131°25, but by keeping the potentials of the timing line and data line the same so that no effective value is applied to the liquid crystal display during the pause period. Even with the same selection period, the effective value ratio applied to the liquid crystal can be improved, and therefore the contrast can be improved.

Generally, taking the voltage averaging method of the V-MV method as an example, if the duty is set to 1/D, the effective value ratio between when the liquid crystal is lit and when it is not lit, which is a measure of contrast, is divided into the rest period. When the number of scanning lines is M, the effective value ratio is obtained by driving so that the effective value becomes 0 within the pause period, and the ratio is clearly larger in equation (2) than in equation (1). For example, N=1[1, D=131. When M=30, the ratio is 1.089 in the conventional case, but it increases to 1.104 in the driving method of the present invention, indicating that the contrast is improved.

Fig. 5 explains the drive waveform of the present invention, and shows the timing using horizontal synchronization signal (-8) as the standard.
It is composed of frames, and one field is 1/6
It is 0 seconds. For simplicity, the odd and even fields are considered to be the same signal. Among the five scanning lines at 262° within one field period, m lines are used as the display period, and one line and nine lines near the vertical blanking period are set as rest periods. The timing lines 01 to CfrL are sequentially scanned from 01 within the display period and end at Om. At this time, amplitude-modulated display data is input to the data lines S1 to sn. The amplitude of this data line is ■. -Nvo's t
In the applanation and enhancement method, it becomes 2■o. What is characteristic about this waveform is that the data line is at rest, and in odd frames, VN80. In even-numbered frames, VNsB is set to the same potential as the non-selection level of the timing line, and no voltage is applied to the liquid crystal during the rest period, that is, to prevent the effective value from increasing during this period. Also, the frame signal fL is
This is a basic signal for AC inversion drive for every odd-numbered frame and even-numbered frame.

FIG. 6 is a block diagram of a data line drive circuit that implements the method shown in FIG. 5, and is composed of voltage selection circuits 10 to 16. 'The voltage selection circuits 10 to 12 are circuits for inverting the polarity in response to the frame signal fL, and the voltage selection circuits 13 to 14 are circuits for inverting the polarity in accordance with the frame signal fL. This is a circuit to make it. Further, the voltage selection circuits 15 to 16 are circuits for inputting the drive output to the data isi according to the display data input D1, and n blocks 17 are prepared.

As described above, the present invention improves the display contrast of the liquid crystal by providing a period in which the display is paused near the vertical blanking period, and maintaining the potential difference between the data line and the timing line at 0 during the pause period. In addition to the above-mentioned examples, all liquid crystal matrix panels can be applied to scanning methods using double or quadruple timing lines, such as an upper and lower split electrode method or a double matrix method.

[Brief explanation of the drawing]

Figure 1 shows an example of the configuration of an IJ sock panel (see Figure 2).
The figure shows the driving waveform, and FIGS. 3 and 4 show examples of signals for the raster and scan systems, where VS is a vertical synchronizing signal and H-S is a horizontal synchronizing signal. FIG. 5 shows an example of the driving waveform according to the present invention, in which p and q are the rest periods, poison is the display period, 01 to am are the signal waveforms of the timing line, and Si is the signal waveform of the data line. Also, Figure 6 is the 5th
It is a block diagram forming the drive waveform of the data line in the figure,
Voltage selection [0 is composed of circuits 10 to 16. Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Tsutomu Mogami-4

Claims (1)

[Claims] (]) In a matrix display panel in which display data is provided via a data line to a pixel selected by a timing line, a display stop period is provided near the vertical blanking period, and during the pause period, the timing line and data are A matrix characterized by keeping the lines at the same potential.
Display panel drive method.