JPS62209515A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To make flicker invisible to human eyes by raising the frequency component of flicker. CONSTITUTION:Voltage waveforms impressed to picture elements connected to scanning electrodes (i)-i+3 are shown in figures (a)-(d) respectively, and signals corresponding to scanning electrodes (i) and i+1 are square waves having 15Hz and have 90 deg. phase difference because polarities are inverted and off and even fields are shifted by one field period. Therefore, 90 deg. phase difference is generated successively even if the variation of light intensity of 15Hz component is generated in every scanning electrode. In case of a normal visual length, discrimination of only picture elements in one row is impossible and the variation of light intensity on the whole of a liquid crystal panel is seen. That is, only 60Hz component of the variation of 90 deg. phase difference shown in a figure (e) is visible. This 60Hz component is a flicker component generated on a television receiver using a general CRT and is almost invisible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for displaying an interlaced image 15 in which the number of scanning electrodes is approximately equal to the number of scanning lines (NTSC
(approximately 480 yen), which is the third in line with high-resolution liquid crystal displays.

BACKGROUND OF THE INVENTION FIG. 4 shows an example of acti 1 matrix h type driving according to a conventional technique. In FIG. 4, IG, L liquid crystal panels, 2 are signal f+ electrodes, 3 are scanning electrodes, 4 is a number hold circuit for line-sequentially driving the signal electrodes 2, and 5 is a sample bold circuit 4. A shift register circuit 6.6' is a shift register circuit for driving the scanning electrode 3. Reference numeral 7 denotes rainwater in the liquid crystal panel 1, which is composed of one FET per pixel and a liquid crystal cell as shown in FIG. In FIG. 5, 8 is an F l'E which is connected to the signal electrode 2 and the scanning electrode 3 to perform a switching operation.
T, 9 indicates a liquid crystal cell, and one end of the liquid crystal cell 9, although not shown, is connected to a common electrode of a glass substrate opposite to the glass substrate with FEr.

Next, the operation will be explained. (Video image in Figure 4)
Add the bidet 71 signal from the input terminal 10, and connect the four-phase amplifier/11
Alternatively, the inverting amplifier 12 amplifies the polarity, and the changeover switch 13 selects either polarity. This changeover switch 13 is controlled by a signal applied to an inversion pulse input terminal 14. This added im month number 1 synchronized to the manual synchronization signal.
The pulse size is 15 II 2 which inverts every frame. This means that in a certain frame period, the video (r: '1
3, and in the next frame period, a negative polarity video A signal is added, and AC voltage is applied to the liquid crystal cell! [This is to mark h1. The video signal No. 4f3 whose polarity is inverted every frame is sequentially sampled and held in the pull-hold circuit 4, and the signal electrodes 2 are driven line-sequentially.

Next is the scanning side, when it is an odd field! Activate L side shift register 6, I11<63.4μS)
Every other scan electrode is driven sequentially from the top. At the time of the next even field, the right shift register 6' is operated, and the scan electrodes that were not driven in the previous odd field are driven, and one frame of image is projected as a whole.
Ru.

ff! The movements of each Ryoki are described during the song. i in figure 5
During the period when the scan pulse is applied to the scan electrode 3, the FET 8 is conductive, and the voltage of the No. 2 electrode 2 is applied to the liquid crystal cell 9, and at the same time, the liquid crystal cell 9 is charged with electricity corresponding to the video signal. do. During most of the period when no scanning pulse is applied to the scanning electrode 3, [El-8 is in a non-conducting state,
Since the charges charged in the liquid crystal cell 9 are held as they are, an electric current FE equivalent to static driving is applied to the liquid crystal cell 9. Corresponding to the polarity of the video A signal being reversed so that one cycle occurs in two frame periods, the voltage applied to each liquid crystal cell 9 similarly becomes one cycle in two frame periods (1511Z'r''). It will be driven #J.

Problems to be Solved by the Invention In the conventional example as described above, since the driving field is responsible for one scanning electrode and the adjacent scanning electrode, the phase difference between the two scanning electrodes is one field period. That will happen. This situation will be explained with reference to FIG.

FIG. 6(a) shows the fa pressure waveform applied to a liquid crystal cell connected to a scanning electrode driven in an odd field. The rising and falling times indicate that a scanning pulse has been applied to the scanning electrode and the voltage has changed to a new voltage. FIG. 6(b) shows the applied voltage waveform of the liquid crystal cell connected to the adjacent scanning electrode driven during the even field period. In this way, the timing is shifted by one field period. The intensity α of the light transmitted through the liquid crystal cell at this time is not necessarily constant. This is FE
Factors that cause iI current to be added to the liquid crystal cell due to conditions such as leakage current during the non-conducting period of T, gate pulse ilj due to the capacitance between the gate and drain of the FET, and variations in the sample and hold circuit that drives the signal fij electrode. There are two types: 1 and 2, which cannot hold the charge due to the resistance of the liquid crystal itself.

Since the latter element does not have a DC component, the light intensity component (a) has the same parabolic waveform regardless of the negative polarity of f. The former element results in a waveform with roughly positive and negative polarities, and the actual light intensity waveform has a 1511z component and 30
This results in a waveform in which 117 parabolic waveform components are overlapped. Similarly, in the even field of FIG. 6(b), the waveform is as shown in FIG. 6(d). This scan? If you look near the a pole, you will see that it is long and narrow.
The light intensity along the scanning electrode cannot be recognized separately, but the waveforms of (C) and (d) are combined, resulting in alternating bright peaks and low valleys, as shown in Figure 6 (). Na1511
It appears as the intensity of the z-component light. Even if this low frequency component is quite strong, it causes shimmer, so-called flicker, and gives an unpleasant feeling. This is I”
This problem can be solved by setting the characteristics of the ET to an ideal point and eliminating the DC component applied to the liquid crystal hill, but it has been extremely difficult to improve the characteristics of a large number of FETs.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a liquid crystal display device in which the frequency component of flicker is increased so that it is not perceived as flicker by humans. .

In order to solve the above-mentioned problems (1), the present invention applies a pulse that sequentially scans the scanning electrodes every other time in a certain field period, and in the next field period, scans the scanning electrodes in the previous field period. A pulse is applied to sequentially scan the scanning electrodes between the scanned electrodes, a signal whose polarity is inverted with respect to the common electrode is applied to the common signal electrode every horizontal scanning period, and a pulse is applied to the pixel electrode in two frames. It is constructed so that one cycle of belief is added.

Effect With the above configuration, the phase of the voltage waveform applied to the liquid crystal cell is shifted by 90° for each scanning electrode tree, and driven so that one period is made up of four trees, and this driving causes the flicker frequency component to be 6011z. It becomes higher and no longer feels like flicker to the human mouth, thereby eliminating discomfort.

EXAMPLE An example of the present invention will be described below based on the drawings. 1st
In the figure, a liquid crystal panel 1, which operates in the same manner as in Figure 4,
IJ pull hold circuit 4, shift register circuits 5, 6
．． 6' etc. are given the same number and detailed explanation will be omitted.

The operation of the switching pulse generation circuit 15 that generates a pulse that drives the changeover switch 13 in FIG. 1 will be explained with reference to FIG.
Ru. Figure 3(a) shows an odd field ``,'' switching pulse that reverses polarity in one horizontal period angle.Figure 3(b)
) shows the switching pulse in the even field, and Fig. 3 (a
), the polarity is reversed every horizontal period, but of course 1
/2 horizontal period 111 The phase shifts by 3 degrees, and although it is not shown in Fig. 3, in the next frame period, Fig. 3 (a)
(b) Both phases are inverted to perform frame inversion AC driving. FIG. 3(C) shows a pulse applied to a certain scanning electrode i selected in an odd field. Figure 3 (a
According to the output of the switching pulse ), a video signal of positive polarity is applied to the pixel connected to this scanning electrode i. The J scan pulse shown in FIG. 3(d) is applied to the scan electrode +4i+2 two places below the scan electrode i, and a negative polarity signal is applied to the pixel connected to this scan electrode. . In the next even field period, one scan pulse as shown in FIG. 3(0) is applied to scan electrode 1-11 between scan electrode i+
A scanning pulse shown in FIG. 3(f) is added to 3, and video signals of positive and negative polarity are applied to each pixel.

Then, in the next frame, each polarity is reversed.

FIGS. 2(a) to (1) show the voltage waveforms applied to the pixels connected to scan electrode i % i +3. As mentioned above, the polarity of scan electrodes i and i+1 is reversed, and the polarity is odd,
In an even field, there is a shift of one field period, resulting in a rectangular wave of 15H2 and a phase difference of 90°, as shown in FIGS. 2(a) to 2(d). Therefore, as explained in the conventional example, even if a variation in the light intensity of 15112 components occurs for each scanning electrode, the phase difference will be 90° in sequence. At a normal viewing distance, it is impossible to distinguish just one horizontal row of pixels, and the light intensity fluctuations of the entire crystal panel are seen. In other words, what is perceived visually and L is shown in Figure 2 (i
It is only the 6011z component of the variation in the phase difference of '90° shown in ll). This 60fiz component is a general CRT
This is a flicker component that occurs even in pre-vision receivers that use the same technology, and is a component that is hardly perceptible.

Effects of Kitamon According to the present invention, in a fully interlaced liquid crystal display panel that displays a screen with 480 scanning electrodes, only 60 II Z flicker components are generated and there is no discomfort. It becomes possible to realize a liquid crystal panel. However, the characteristics of FL"T include 24 scanning electrodes.
It only needs to be about the same size as 0 liquid crystal panels, and its practical value is high.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a liquid crystal display device according to an embodiment of the present invention, FIG. 5 shows the phase of the polarity switching pulse and scanning pulse of the Bianio signal used in the present invention, FIG. 4 is a conventional configuration diagram, FIG. 5 is a detailed internal view of a liquid crystal cell, and FIG. 6 is a conventional method. The applied voltage waveform of the liquid crystal hill and the light intensity waveform of the liquid crystal cell are
This is an acceptance drawing. 1...Liquid crystal panel, 2...jLj electrode electrode...
scanning electrode, 4...9 sample hold circuit, 5... shift register circuit driving the sample hold circuit, 6
, 6'...shift register circuit for driving the scanning electrode,
7... Pixel, 10... Video signal input terminal, 11...
... Video signal in-phase amplifier, 12 ... Video signal inversion amplifier, 13 ... Changeover switch, 15 ... Changeover pulse generation circuit representative fS No. 1 tablet positive 31. Scan electrode 718. ! ! ! J elementary 10-c'f age 11 entering tytriititt seven fjj
M': lji1u7) ふ・ 4J::f さを f191i, にあ)79 /j-L'fjll)e)L,? 9i eB≦. Figure 2 (e) Hahahahahahahaha Figure 7 Figure 4? I45 Figure ox j color Figure 6 (ε), Go to 7. l\

Claims (1)

[Claims] 1. It has a liquid crystal layer sealed between two substrates, one substrate is provided with a common electrode, the other substrate is provided with a plurality of scan electrodes and a plurality of signal electrodes, and the scan electrode and the A liquid crystal display device in which a switching element and a pixel electrode are connected near the intersection of signal electrodes, and the light transmission characteristics of the liquid crystal layer change depending on the voltage applied between the common electrode and the pixel electrode, and the light transmission characteristics of the liquid crystal layer change every other layer during a certain field period. A pulse is applied to sequentially scan the scanning electrodes, and in the next field period, a pulse is applied to sequentially scan the scanning electrodes between the electrodes scanned in the previous field period, and a pulse is applied to the signal electrode every horizontal scanning period. A liquid crystal display device configured such that a signal having an inverted polarity is applied to the common electrode, and a signal of one cycle is applied to the pixel electrode in two frames.