JPH0458036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a liquid crystal display device.

When displaying an image on the liquid crystal display device shown in FIG. 1 (101 is an X driver, 102 is a Y driver, and 103 is a liquid crystal (display) panel), the drive method shown in FIG. 2 has conventionally been used. It's here. The waveforms of each point on Figure 1 (X, Y driver output, liquid crystal applied voltage at the X-Y intersection) are indicated by the (X, Y) coordinates shown in Figure 1.

FIG. 2 is a driving waveform diagram of a conventional liquid crystal display device.

As is clear from the waveforms (0,1), (1,0), (1,1) in Figure 2, the output waveforms of the X and Y drivers change every vertical scanning period (hereinafter abbreviated as 1V). In contrast, the selection time of the voltage applied to the liquid crystal at the intersection is one horizontal scanning period (hereinafter abbreviated as 1H). This conventional example is a driving method in which a gradation component is added to the output waveform of the X driver by modifying the voltage averaging method. When performing gradation display using this voltage averaging method, variations in applied voltage during non-selection adversely affect gradation characteristics. The remaining waveforms in Figure 2 consider this negative effect. (2,0) is the entire lighting signal, and (3,0) is the lighting signal for only the selected line (1
All lines are not lit) waveform. The results of the consideration are as shown in (2, 1) and (3, 1),
The effective voltage for full lighting (2, 1) is higher. This is because the effective voltage at (2, 1) has the same polarity as the effective voltage applied during the selection period and the effective voltage applied during the non-selection period, and the effective voltage at (3, 1) has the same polarity as the effective voltage applied during the selection period. This is because the effective voltage applied during the non-selection period and the effective voltage applied during the non-selection period have opposite polarities. In normal black-and-white binary character display, this level of difference in effective values is not a problem because the operating margin is wide. However, gradation display poses a problem because the operating margin is narrow, making it impractical. As described above, it is difficult to display gradations using the conventional voltage averaging method.

The present invention eliminates such drawbacks, and its purpose is to solve the problem of dynamic drive type liquid crystal display devices such as simple matrix type liquid crystal display devices and liquid crystal display devices using non-linear elements, which are weak points of these liquid crystal display devices. The objective is to display good intermediate gradations. Another object of the present invention is to effectively prevent crosstalk and flicker in these liquid crystal display devices.

Another object of the present invention is to realize a liquid crystal display device with extremely high image quality without using expensive thin film transistors that are good at displaying intermediate gradations as switching elements.

Further, in order to achieve the above object, the liquid crystal display device of the present invention includes a liquid crystal sealed between a pair of substrates,
In a liquid crystal display device in which a liquid crystal is dynamically driven by electrodes arranged in a matrix, a scanning signal generating means supplies a scanning signal to each pixel electrode in each row direction, and a video signal is supplied to each pixel electrode in each column direction. the scanning signal has a polarity inverted every integer number of rows, and the polarity of the video signal is inverted every integer horizontal scan in synchronization with the inversion of the scanning signal. shall be. The present invention will be described in detail below based on Examples.

FIG. 3 is a driving waveform diagram of the liquid crystal display device of the present invention. (0,1), (0,2), in Figure 3
(0, 3) is an output waveform diagram of the Y driver.
As evident in the waveform diagram, odd Y line and even Y line
A feature of the driving method of the present invention is that the polarities of the lines are reversed.

(1,0) and (2,0) in FIG. 3 are output waveform diagrams of the X driver. (1,0) is a full lighting signal,
(2,0) is a signal that only the selected line lights up (all lines are off except for one line). This was chosen for comparison with the same signals in FIG. As is clear from the above explanation and waveform, the output waveform of the X driver is a gradation signal that is inverted every 1H, and the driving method of the present invention is characterized in that the gradation signal is further inverted every 1V. .

(1, 1) and (2, 1) in FIG. 3 are liquid crystal applied voltage waveform diagrams according to the driving method of the present invention. In the non-selection period, even though (1, 1) is fully lit and (2, 1) is not fully lit, the signal is input.
The average applied voltage level (indicated by a broken line in FIG. 3) during the non-selection period is the same. This is because the voltage levels indicated by the broken lines in FIG. 3 are equal. Therefore, the influence during the non-selection period can be made equal between each line. That is, compared to the conventional example, halftones can be expressed better.

In Figure 3, all lighting signals and lighting signals for only one line were handled, but the video signal has a correlation with each adjacent line signal, and the gradation signal every 1H is an approximation, so if it is inverted every 1H, As shown in FIG. 3, the average level when not selected is also almost the same.

The drive waveform diagram of the liquid crystal display device of the present invention shown in FIG. It is clear that similar objectives can be achieved.

FIG. 4 shows an embodiment of a driving circuit for a liquid crystal display device according to the present invention. In FIG. 4, the video signal input to 406 is amplified by the PNP transistor 401, and the video signal of both positive and negative polarities is output to 402, 4.
It is taken out from the load resistance of 03. The positive and negative polarity video signals are switched by an analog switch 404 and input to an X driver 410. The 40 controls the 404 analog switch.
5 exclusive or gate. Typically this control is a 408 frame signal input (1V
Invert each time. ), but the inversion every 1H, which is a feature of the present invention, is controlled by the input 407 (even-odd horizontal line signal). The 410 X driver is the 414 shift register (411
412 is a sampling clock input, and 412 is a sampling data input. ), a sample hold circuit consisting of an analog switch 415, and a capacitor 416, and a line hold circuit consisting of an analog switch 417, a capacitor 418, and a line amplifier 419.
When the analog switch output of 404 is sampled and held by the sample hold circuit, the analog switches of 417, which are controlled by the input of 413 (X line hold signal), turn on and off all at once, and are held in the capacitor of 418, and then sent to the line driver of 419. The X line is driven by.

The Y driver 420 is composed of a shift register 423 (421 is a clock input, 422 is a data input), an analog multiplexer 424, a non-inverting line driver 425, and an inverting line driver 426.

Both the Y driver 423 and 424 of the 420 remain the same as before, and applying an inverted output to each Y line of the present invention means that the Y driver 423 and 424 of the 420
It consists of 5,426 non-inverting and inverting line drivers. Normally, each line can be inverted 424 times without using an inverting or non-inverting driver.
It can be handled inside the analog multiplexer of

As described above, the liquid crystal display device of the present invention is a liquid crystal display device in which a liquid crystal is sealed between a pair of substrates and the liquid crystal is dynamically driven by electrodes arranged in a matrix. It has a scanning signal generating means for supplying to the pixel electrodes, and an image signal generating means for supplying a video signal to each pixel electrode in the column direction, the polarity of the scanning signal is inverted every integer number of rows, and the video signal is Since the polarity is inverted every integer horizontal scan in synchronization with the inversion of the scanning signal, it has the following remarkable effects.

(a) The effective value of the applied voltage when not selected is almost the same regardless of the lighting state of other pixels. Therefore,
In a dynamic drive type liquid crystal display device such as a simple matrix type liquid crystal display device or a liquid crystal display element using a non-linear element, it becomes possible to perform good halftone display, which has been weak in these liquid crystal display devices. Furthermore, for the same reason, crosstalk and flicker can also be effectively prevented in these liquid crystal display devices.

Therefore, a liquid crystal display device with extremely high image quality can be realized without using an expensive thin film transistor, which is good at displaying intermediate gradations, as a switching element.

(b) Dynamic drive type liquid crystal display devices, such as simple matrix type liquid crystal display devices and liquid crystal display devices using non-linear elements, have a simpler manufacturing process and are easier to manufacture than liquid crystal display devices using thin film transistors. The manufacturing cost is low because the temperature is low and the yield is good. Furthermore, since an inexpensive substrate can be used, a large display device can be provided at a low price.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional liquid crystal display device. FIG. 2 is a driving waveform diagram of a conventional liquid crystal display device. FIG. 3 is a driving waveform diagram of the liquid crystal display device of the present invention. FIG. 4 is a driving circuit diagram of the liquid crystal display device of the present invention. 101 is a Y driver, 102 is a Y driver, and 103 is a liquid crystal display panel. 4
01 is a PNP transistor, 402 and 403 are load resistors, 404 is an analog switch, 405 is an exclusive OR gate, 406 is a video signal input, 407 is an even-odd horizontal line signal input, and 408 is a frame signal input. 410 is the X driver, 411 is the sampling clock input, 412
is a sampling data input, 413 is an X line hold signal input, 414 is a shift register, 4
15,417 is an analog switch, 416,41
8 is a capacitor, and 419 is a line driver. 420 is a Y driver, 421 is a clock input, 422 is a data input, 423 is a shift register, 424 is an analog multiplexer, 425 is a non-inverting driver, and 426 is an inverting driver.

Claims (1)

[Claims] 1. In a liquid crystal display device in which a liquid crystal is sealed between a pair of substrates and the liquid crystal is dynamically driven by electrodes arranged in a matrix, a scanning signal generating means for supplying a scanning signal to each pixel electrode in each row direction;
and an image signal generating means for supplying a video signal to each pixel electrode in each column direction, the polarity of the scanning signal is inverted every integer number of rows, and the polarity of the video signal is synchronized with the inversion of the scanning signal. A liquid crystal display device characterized by being inverted every integer horizontal scan.