JPS63304294A - Liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a liquid crystal display device.

2. Description of the Related Art In recent years, liquid crystal display devices have attracted attention as display devices that can replace CRTs. The main reasons for this include low power consumption, low voltage operation, and the ability to make the thickness of the display section considerably thinner than that of a CRT. The current situation is that pocket screen-sized LCD televisions are already on the market. The drive system for currently commercially available LCD televisions consists of two LCD panels: an upper LCD panel and a lower LCD panel.
A dual-matrix drive system that drives the upper and lower LCD panels at the same time by dividing the LCD panel, and a pause phase state in which one panel is driven while the other panel is in a dormant state. There are drive methods, drive methods with pause phase, etc.

An example of the conventional liquid crystal display device mentioned above will be described below with reference to the drawings.

Conventionally, this type of liquid crystal display device was manufactured by Japanese Patent Publication No. 59-121391.
It is indicated in the publication.

FIG. 5 is a block diagram of the liquid crystal display device, and FIG. 6 is a two-part electrode configuration and wiring diagram. 1 is a liquid crystal panel, 2 is a column side driver, 3 is a row side driver, 4 is a control unit section for controlling the driver, 5 is a drive power supply voltage generation section, 6 is a row side electrode group, and 7 is a column side electrode group.

The operation of the liquid crystal display device configured as described above will be described below.

When the liquid crystal matrix panel is divided into two parts, an upper liquid crystal panel and a lower liquid crystal panel, and the liquid crystal panel is driven, the shift clock and scanning panel generated by the control signal generator are applied to the row driver, and the row driver generates a signal as shown in FIG. One screen is assembled by shifting the indicated shift data using a shift clock.

Problems to be Solved by the Invention However, the above configuration has the problem that as the number of scanning lines (N) increases, the contrast decreases due to the influence of crosstalk. A method has been considered in which three electrodes are simultaneously scanned. However, this method has a problem in that the resolution in the horizontal direction is reduced. That is,
This has had the contradictory problem of improving the contrast but decreasing the resolution in the horizontal direction.

In view of the above-mentioned problems, the present invention has been developed in view of the above problem, and since there is a strong correlation in the vertical direction of the screen when displaying moving images such as TV images, there is little deterioration in image quality even if the resolution is lowered.
shall be increased to improve contrast. Furthermore, in binary display that does not require halftones, such as character display, the number of scanning electrodes (n) is reduced to improve resolution.

Means for Solving the Problems In order to solve the above problems, the liquid crystal display device of the present invention has the number of scanned electrodes; This is a liquid crystal display device having a configuration in which an optimum bias voltage value and optimum brightness can be obtained.

By varying the number of electrodes scanned in the action 1v period; by varying the number of electrodes scanned as set above; by setting the optimum bias voltage value and optimum brightness for one electrode,
When displaying a moving image such as a TV image, there is a strong correlation in the vertical direction of the screen, so even if the resolution is lowered, there is little deterioration in image quality, so the number of electrodes that are simultaneously scanned (n) is increased to improve contrast. Furthermore, in binary display such as character display, a clear and bright image is displayed by reducing the number of scanning electrodes (n) and increasing resolution.

EXAMPLE Hereinafter, a liquid crystal display device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention. 1 is a liquid crystal panel, 2 is a column side driver, 3 is a row side driver, 4 is a control unit section for controlling the driver, 5 is a drive power supply voltage generation section, and 8 is switched to the optimum bias voltage value corresponding to the number of electrodes to be scanned. This is a switch for In FIG. 2, the shift clock applied to the row driver and the number of scanned electrodes are one.

FIG. 3 is a block diagram inside the row driver.

9 is a power supply control circuit, 10 is a shift register, 1
1 is a level shifter, 12 is an LCD driver, 13 is an in-cover sofa, and 14 is an out-cover sofa. FIG. 4 shows the output signal waveform output from the row driver.

The case where the number of scanned electrodes is n-2 will be described below using FIGS. 1, 2, 3, and 4.

When driving with a matrix type liquid crystal display panel, if the scanning line; Therefore, a desired image is displayed by applying voltage to non-selected picture elements using a voltage averaging method.

The ratio of the effective value voltage of the selected picture element and the non-selected picture element when driven by the voltage averaging method; let it be α, and in order to maximize α, scan from the above formula from dα/ d a = Q. As the number of electrodes (n) increases, the ratio of effective voltages (α) decreases. Further, when the voltage applied to the liquid crystal is Vn and the bias voltage is Vbias, Vbias=Vn/α.

From this, it can be seen that as the effective value voltage ratio α becomes smaller, the bias voltage Vbias becomes larger and the voltage operation margin becomes larger.

A shift lock and a scanning pulse (n=2) are applied to the row driver from the control unit shown in FIG.

In FIG. 3, the scanning pulse taken into the row driver is shifted by a shift register. The shifted internal data is sent to a level shift circuit which is a level interface. Furthermore, in the LCD driver section, the FR
(AC signal) The power supply control circuit selects the combined liquid crystal drive voltages Von and Voff to generate an output signal. As shown in FIG. 2, two consecutive pulses of serial data are transferred by shift lock during the lv period. The output waveform of the driver at this time is as shown in FIG.

The duty at this time is equivalent to 1/2 of the duty in the serial data l pulse during the 1v period. By lowering the duty, the contrast increases,
Color reproducibility also improves. Furthermore, a large operating margin can be secured when driving the liquid crystal. By making the number of scanning pulses (n) variable in the 1v period in this manner, it is possible to display a high quality image as described above. Note that the number of scanning pulses in one period; n is not limited to n=2.

Effects of the Invention As described above, the present invention provides a liquid crystal display device in which electrodes scan simultaneously in a 1V period, since there is a strong correlation in the vertical direction of the screen when displaying moving images such as TV images, and there is little deterioration in image quality even if the resolution is lowered. Increasing the number n equivalently lowers the duty, which increases contrast and improves color reproducibility. In addition, in binary display such as character display, the number of electrodes to be scanned; the number of electrodes to be scanned simultaneously by the display image, such as 0 or more, which displays a clear and bright image by reducing the number of n and increasing the resolution; By varying n, the number of electrodes scanned simultaneously; the bias voltage value of the drive voltage applied to the liquid crystal panel is set to the optimum bias value corresponding to n, and the brightness at that time is set to be maximized. This increases the operating voltage margin when driving the liquid crystal, and when displaying an image, it is possible to obtain a bright, high-quality image with good color reproducibility.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention, Fig. 2 is a shift clock and shift pulse waveform diagram applied to the row driver, Fig. 3 is a block diagram of the row driver, and Fig. 4 is a row driver Figure 5 is a block diagram of the liquid crystal display device, Figure 6 is a diagram of the electrode configuration and wiring diagram divided into two parts, and Figure 7 is a signal waveform diagram of shift clocks, scanning pulses, and shift data. It is. 1...Liquid crystal panel, 2...Column side driver, 3...Row side driver, 4...
・Control unit section for driver control, 5...
. . . Drive power supply voltage generation section, 8 . . . Shift data and bias value changeover switch. 9...
...Power supply control circuit, 10...Shift register, 11 is level shift, 12...LC
D driver, 13... Input buffer, 14...
...Outer sofa.

Claims (1)

[Claims] The number of scanning lines of a liquid crystal panel in which a liquid crystal is sandwiched between electrodes configured in a matrix is N.The number of electrodes scanned simultaneously is variable. A liquid crystal display device characterized in that a bias voltage value of a drive voltage applied to a liquid crystal panel is made variable in accordance with the number of liquid crystal panels.