JPH10239666A - Driving method for liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent crosstalk from being generated by raising a signal-side applied voltage to a nearly intermediate potential between a selection and a nonselection level in a specific time when the applied voltage is varied from the selection level to the nonselection level, and holding a scanning-side applied voltage at the nonselection level at this time. SOLUTION: When a selection line for a scanning signal shown by a LOAD signal is switched, the signal-side applied voltage (SEG-OUT) is varied from the selection level to the nonselection level. When, however, VO is the selection level, VB1 is the nonselection level and when the V1 is the selection level, on the other hand, the VO is the nonselection level. The voltage is raised to the nearly intermediate potential between the selection level and nonselection level in the specific time and within this specific time, the scanning-side applied voltage (COM-OUT) is held at the selection level VMC. Further, when DISP is set to L, the DISP is changed from H to L almost in the time of variation from the scanning-side selection level to the nonselection level VM at the pixel farthest from the output of a driver IC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a liquid crystal display device having a simple matrix liquid crystal panel.

[0002]

2. Description of the Related Art As a driving method of a liquid crystal display device having a simple matrix structure, there is a so-called "voltage averaging method" for averaging voltages at a half-selected point and a non-selected point. According to the display wiring structure of the simple matrix liquid crystal display device using the voltage averaging method, the transparent electrodes arranged on the scanning substrate and the transparent electrodes arranged on the signal substrate intersect, so that the liquid crystal is formed. A scanning region driver IC is connected to the former transparent electrode, and a signal side driver IC is connected to the latter transparent electrode. Further, a driving power supply circuit constituting a voltage averaging method is formed by the scanning driver IC and the signal driver IC.

However, the simple matrix liquid crystal display device having the above configuration has a problem that a tailing phenomenon called crosstalk occurs as compared with a liquid crystal display device having an active matrix structure. This crosstalk is caused by the formation of a capacitor at the intersection of the transparent electrodes facing each other,
This is due to the fact that the applied voltage does not immediately rise, and the voltage undergoes a so-called "waveform rounding" (waveform distortion).

Various methods have been proposed to solve this problem. For example, techniques for improving the material such as lowering the resistance of the transparent electrode and lowering the permittivity of the liquid crystal material, a technique for disposing driver ICs on both ends of the transparent electrode, and correcting a decrease in the effective value due to distortion of the driving waveform. For this purpose, a technique of applying a correction pulse has been proposed.

[0005]

However, the effect of the crosstalk improvement is still not satisfactory, and when similar driving circuits are arranged near both ends of the scanning side electrode, the driving circuit can be further improved. A space is required, thereby increasing the external dimensions of the product, which makes it impossible to meet market needs for downsizing of notebook computers and the like.

Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a high-quality and small-sized liquid crystal display device by a driving method that can easily reduce crosstalk while achieving downsizing. Is to provide.

[0007]

According to the driving method of the liquid crystal display device of the present invention, in a liquid crystal display device having a liquid crystal panel having a simple matrix structure, when a selection line of a scanning signal is switched, a signal side applied voltage is changed from a selected level. When changing to the non-selection level, the potential is brought to a substantially intermediate potential between the two levels for a predetermined time, and the scanning-side applied voltage is set to the non-selection level within the predetermined time.

Further, the present invention provides the above driving method,
The scanning-side applied voltage at the non-selection level and the intermediate potential are made substantially the same.

[0009]

FIG. 1 is a block diagram of a driving circuit used in a method of driving a liquid crystal display device according to the present invention, and FIG. 2 is a driving waveform diagram obtained by using the driving circuit. Also,
FIG. 3 is a block diagram of a driving circuit used for a conventional driving method of a liquid crystal display device, and FIG. 4 is a driving waveform diagram according to the driving method. In the present invention and the related art, the same reference numerals are given to the same portions.

First, according to the present invention, in FIG. 1, 1 is a liquid crystal panel having a simple matrix structure of 640 × 3 (R, G, B) × 480 dots and a duty of 1/240. 2 is a signal side driver IC, 3 is a scanning side driver IC, and 4 is a drive power source. Reference numeral 5 denotes a DISP signal timing generator.

[0011] CP is a data transfer clock, LO
AD indicates a data latch signal, FRAM indicates a scan start signal, DF indicates an AC inversion signal, UD0 to 7 indicate upper screen data, and LD0 to 7 indicate lower signal data. Further, as the driving power supply 4, the signal-side power supplies V0, VMS, V1, and the scanning-side power supplies VH, VMS, V
L.

Next, the timing in the driving method of the present invention is shown in FIG. When switching the selection line of the scanning signal as indicated by the LOAD signal, the signal side applied voltage (S
EG-OUT) from the selected level to the non-selected level. However, when V0 is the selection level, V1 is the non-selection level, and when V1 is the selection level, V0 is the non-selection level. Then, at the time of the above-described switching, the voltage reaches a substantially intermediate potential VMS between the selected level and the non-selected level in a predetermined time, and within this predetermined time, the scanning-side applied voltage (COM-OUT) is set to the non-selection level VMC.

In detail, in the same figure, the DISP signal input from the outside is processed, the LOAD signal is changed to L (low), and after the CP falls twice, the DISP is changed to H (high).
FIG. Here, the timing of setting DISP to H may be arbitrarily changed. It can be adjusted based on CP. The time for setting DISP to L is from the selection level (V0 or V1) on the scanning side to the non-selection level VM when DISP is changed from H to L in the pixel farthest from the output of the driver IC. I almost matched the time. Further, the scanning side applied voltage (COM-OUT) is set to the non-selection level VMC within the predetermined time.

In the present invention, the non-selection level V
The effect of the present invention can be maximized by making the applied voltage on the scanning side of the MC substantially equal to the intermediate potential.

Thus, according to the driving method of the present invention, no crosstalk occurred. In the above, L
DISP is set to L at the rising timing of OAD (at the start of the selection period of one line on the scanning side). However, a period in which DISP is set to L immediately before the end of one line selection period may be provided.

Next, a driving method of a conventional liquid crystal display device will be described. FIG. 3 is a block diagram of a driving circuit, and FIG. 4 shows a driving waveform. As shown in FIG.
G-OUT) includes V0 and V1, and when DF = H, V0 becomes the selection level and VI becomes the non-selection level. On the other hand, when DF = L, V0 is a non-selection level,
V1 becomes the selection level. In accordance with this, when the scanning-side applied voltage (COM-OUT) is DF = H, the selection level is VL and the non-selection level is VMC. DF = L
In this case, the selection level is VH and the non-selection level is VMC. The scanning-side selection lines are sequentially switched from the rising timing of the data latch signal LOAD. To turn off only the display, set the DISP signal to L
By fixing the output of the signal and scanning to VM,
Only the display can be turned off. With such a conventional driving method, occurrence of crosstalk was recognized.

It should be noted that the present invention is not limited to the above embodiments, and various changes and improvements do not hinder the present invention without departing from the gist of the present invention. For example,
According to this embodiment, the DISP signal timing generator 5 is used. Alternatively, the timing may be obtained by using a monostable multivibrator, a capacitor, and a resistor and utilizing a charge / discharge time.

[0018]

As described above, according to the driving method of the liquid crystal display device of the present invention, when changing the applied voltage on the signal side from the selected level to the non-selected level at the time of switching the selected line of the scanning signal, both levels are changed. By setting the scanning side applied voltage to the non-selection level within this predetermined time while keeping the potential at substantially the intermediate potential of the above, it was possible to prevent the occurrence of crosstalk.

Further, according to the method of driving the liquid crystal display device of the present invention, the occurrence of crosstalk can be most remarkably prevented by making the scanning-side applied voltage of the non-selection level substantially equal to the intermediate potential. Was.

Further, according to the driving method of the liquid crystal display device of the present invention, crosstalk can be more easily eliminated while achieving miniaturization, whereby a high quality and small liquid crystal display device can be provided. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a driving circuit used for a driving method of a liquid crystal display device of the present invention.

FIG. 2 is a driving waveform diagram according to the driving method of the present invention.

FIG. 3 is a block diagram of a driving circuit used for a conventional driving method of a liquid crystal display device.

FIG. 4 is a driving waveform diagram according to a conventional driving method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 liquid crystal panel 2 signal-side driver IC 3 scanning-side driver IC 4 drive power supply 5 DISP signal timing generator SEG-OUT signal-side applied voltage COM-OUT scanning-side applied voltage

Claims (2)

[Claims] In a liquid crystal display device having a liquid crystal panel having a simple matrix structure, when a signal-side applied voltage is changed from a selected level to a non-selected level when a scanning signal selection line is switched, a substantially intermediate potential between both levels is obtained. A method for driving a liquid crystal display device, wherein a predetermined time is reached and the scanning-side applied voltage is set to a non-selection level within the predetermined time. 2. The driving method for a liquid crystal display device according to claim 1, wherein the scanning-side applied voltage at the non-selection level and the intermediate potential are made substantially the same.