JPS63240530A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the unevenness in display and to obtain a liquid crystal display device having a good display grade by dividing the signal electrodes of a liquid crystal panel into two regions and impressing a prescribed gradation signal to the signal electrodes of the other region within the selection scanning period of one region. CONSTITUTION:The electrode constitution of this liquid crystal display device consists of the upper scanning electrodes 21, the upper signal electrodes 22, the lower scanning electrodes 23, the lower signal electrodes 24, etc. With these electrodes, the prescribed gradation signal is impressed to the signal electrodes 22 or 24 of the one region in the period when selective scanning is not executed in all of said regions. The frequency components of the voltage to be impressed to the liquid crystal layer in one frame period can be made nearly the same with all the picture elements. All the frequency components of the signal voltages that can be impressed are impressable to the signal electrodes 22 or 24 by forming the gradation signal to be impressed to the signal electrodes 22 or 24 of the region where the selective scanning is not executed in such a manner as to include at least half of all the patterns of the gradation signals that can be impressed. The biasing of the frequency components which depend on the display pattern is, therefore, considerably relieved. The unevenness in the display is thereby decreased and the uniformity of the display is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device that is effective for use in displays used in video and information equipment, and more particularly to a liquid crystal display device capable of displaying gradations.

2. Description of the Related Art In recent years, there has been an increasing demand for large-screen, thin display devices in the field of information equipment, mainly computers, and in the field of video equipment, mainly televisions, video tape recorders (VTRs), and the like. Among this type of display devices, those using liquid crystals have recently been attracting particular attention because they are thin, lightweight, and easy to realize large screens.

A conventional liquid crystal display device will be described below with reference to the drawings.

FIG. 3 is a configuration diagram of a conventional liquid crystal display device having the most basic configuration, in which 31 is a scanning electrode, 32 is a signal electrode, 33 is a scanning driver, and 34 is a signal driver.

FIG. 4 shows an example of a driving voltage waveform of the conventional liquid crystal display device shown in FIG. 3, which is a voltage waveform applied to one pixel of the liquid crystal panel. Vs is the selection voltage, Vn is the non-selection voltage, Ta is the selection period of the -scanning electrode,
Ts is the application period of the selection voltage, and by varying this Ts, gradation display is possible. Tf is a frame period, and displaying one screen ends in one frame. In order to alternating the voltage applied to the liquid crystal layer, the polarity of the voltage is reversed in subsequent frames. (For example, JP-A-52-
147091 Publication) Problems to be Solved by the Invention However, when the above configuration is driven as shown in FIG. 4, depending on the displayed image and display, the frequency dependence of the liquid crystal panel etc. This had the problem of uneven display.

Therefore, the present invention provides a liquid crystal display device with good display quality that solves the above problems.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to divide the signal electrodes of the liquid crystal panel into two regions, and to scan the signal electrodes of one region during the selective scanning period of the other region. The signal electrodes in the area include
It is configured to apply a predetermined gradation signal.

Furthermore, the gradation signals applied to the signal electrodes in the areas not selectively scanned are configured to include at least half of all the patterns of gradation signals that can be applied.

action The effect of this technical means is as follows.

That is, in the present invention, a predetermined gradation signal is applied to the signal electrode of one region during a period in which all of the regions are not selectively scanned, so that the voltage applied to the liquid crystal layer during one frame period is The frequency components can be made almost the same for all pixels, and display unevenness depending on the pattern of the displayed image can be reduced.

Furthermore, among all the patterns of grayscale signals that can be applied, the grayscale signals to be applied to the signal electrodes in the area that is not selectively scanned are
By configuring the structure to include at least half of the patterns, all the frequency components of the signal voltage that can be applied can be applied to the signal electrodes, so it is possible to significantly reduce the deviation of the frequency components depending on the display pattern, and the display can be further improved. can be made uniform.

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

FIG. 2 is a schematic diagram showing the electrode configuration of a liquid crystal display device according to an embodiment of the present invention. In FIG. 2, 21 is an upper scanning electrode, 22 is an upper signal electrode, 23 is a lower scanning electrode, 24
is the lower signal electrode, 25 is the upper scan driver, 26 is the upper signal driver, 27 is the lower scan driver, 28
is the lower signal driver.

FIG. 1 is a driving voltage waveform diagram of a liquid crystal display device according to an embodiment of the present invention, and in FIG. 1, (a), peak).

TCI is the upper scanning voltage, signal voltage, and applied voltage waveform of the liquid crystal layer, respectively, and (d), (el, and (f) are the lower scanning voltages, respectively.

It shows signal voltage and voltage waveforms applied to the liquid crystal layer.

In FIG. 1, r, VO, Vl, V2. V3. V4゜v5
is set to satisfy the following expression at the driving voltage level.

VO-V5=Vs...-(1) VO-
Vl-Vl-V2-Vn ---...-(21V3-
V4=V4-V5-Vn...-(31Vs is a selection voltage, and Vn is a non-selection voltage.

Ta is the selection period of one scanning electrode, Ts is the application period of the selection signal, and by varying this Ts, gradation display is possible. In this embodiment, the period Ta is divided into 10 equal parts, and T
The case where 3 is varied in 10 steps is shown. This is a period of one frame, and one frame ends the display of one screen. In order to alternating the voltage applied to the liquid crystal layer, the polarity of the applied voltage is reversed in subsequent frames. T
1 is the selection scanning period for the upper region, and T2 is the selection scanning period for the lower region. As is clear from FIG. 1, while scanning the upper region, a predetermined gradation signal is applied to the signal electrode of the lower region, and conversely, while scanning the lower region, the signal of the upper region It can be seen that a predetermined gradation signal is applied to the electrode.

Furthermore, among all the patterns of grayscale signals that can be applied, the grayscale signal applied to the signal electrode during the period when selective scanning is not performed,
It can be seen that at least half of the patterns are included.

Note that the drive waveform shown in FIG. 1 is an example, and for example, the polarity of the applied voltage is reversed every -frame to convert it into an alternating current, but the present invention is not limited to this.

Furthermore, although the gradation signal was applied by changing the gradation level in 10 levels in units of 10 levels, the present invention is not limited to this.

Furthermore, the scanning voltage and signal voltage shown in FIG. 1 are just examples, and any voltage may be used as long as the driving voltage waveform applied to the liquid crystal layer can be obtained.

Effects of the Invention The present invention has a simple configuration in which a liquid crystal panel divided into two regions is applied with a predetermined gradation signal to the signal electrode of the other region during the selection scanning period of one region, and a display image can be displayed. It is possible to obtain the effect that display unevenness depending on the pattern can be reduced.

Furthermore, by making the gradation signal include at least half of all the gradation signal patterns that can be applied, the deviation of the frequency component of the applied voltage depending on the pattern of the displayed image can be reduced. This can further improve display uniformity.

[Brief explanation of the drawing]

FIG. 1 is a driving voltage waveform diagram of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of a liquid crystal display device according to an embodiment of the present invention, and FIG. 3 is a diagram showing a conventional basic liquid crystal display device. FIG. 4, a schematic diagram showing an example of the configuration of a liquid crystal display device, is a drive voltage waveform diagram of a conventional liquid crystal display device. 21... Upper scanning electrode, 22... Upper signal electrode, 23... Lower scanning electrode, 24
...Lower signal bridge, 25...Upper scanning driver, 26...Upper signal driver, 2
7...Lower scan driver, 28...
Lower signal driver, 31...Scan IIT lever,
32...Signal electrode, 33...Scan driver, 34...Signal driver. Name of agent: Patent attorney Toshio Nakao Haka1 person 1'l--
The deflection of the electrode is shown in Figure 2.
IILL” v company business trip

Claims (2)

[Claims] (1) The signal electrode of a matrix liquid crystal panel consisting of a scanning electrode and a signal electrode is divided into two regions, and the pulse width of the signal voltage is varied to display gradation. 1. A liquid crystal display device characterized in that, during a period when one region is selectively scanned, a predetermined gradation signal is applied to a signal electrode in the other region. (2) A patent claim characterized in that the gradation signal applied to the signal electrode in the area that is not selectively scanned is configured to include at least half of all the patterns of gradation signals that can be applied. The liquid crystal display device according to the range (1).