JP3019635B2 - Driving method of liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method for a multi-tone display of a liquid crystal display, and more particularly to a driving method for performing a line inversion display.

[0002]

2. Description of the Related Art A conventional method of driving a multi-gradation display in a liquid crystal display uses a sawtooth wave whose voltage value changes with time as a power supply voltage, and generates a clock signal at an arbitrary timing by using a trigger circuit. An arbitrary trigger is applied to select an arbitrary voltage. The timing of applying this trigger is such that a voltage that can provide luminance at equal intervals can be selected from the voltage-luminance characteristic of the liquid crystal display as shown in FIG. 3 so that the gradation-luminance characteristic has linearity. Was set.

[0003]

In this conventional driving method , a sawtooth wave is used as a power supply voltage. Therefore, when performing line inversion driving, when trying to extract the inversion voltage of the next line, As shown in FIG. 4, there is a problem that the trigger circuit becomes complicated because the period of the trigger signal becomes irregular.

[0004]

According to the driving method of the liquid crystal display of the present invention, the inclination angles of both sides are equal to the power supply voltage.
It is characterized in that a triangular wave having a side triangular shape is used, and a trigger signal having a constant cycle is used for extracting an inversion voltage of the next line during line inversion driving.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 shows a voltage waveform and a trigger signal according to the first embodiment of the present invention. In this embodiment, both sides are inclined as the power supply voltage.
An isosceles triangular triangular wave having the same oblique angle is used. When the midpoint of the voltage fluctuation of the triangular wave of the power supply voltage is connected, the time at which this line cuts the waveform matches one line display time, and the voltage at the midpoint is the offset voltage of the voltage applied to the opposite electrode of the liquid crystal. Set the waveforms to match. Thereby, for example, when inverting and extracting an arbitrary voltage V1 for each line, a trigger is applied at time t1 in the line 1 section, and + V
Trigger at time t1 'in section 1 and line 2 and -V
1 can be obtained, and at this time, the trigger cycle of the V1 trigger signal CLK1 can be made constant (= 1 line display time). The same applies to V2 and V3. Although FIG. 1 shows three voltage values from V1 to V3, eight voltage values can actually be set for eight gradations.

While the trigger signal of the first embodiment is based on duty control, the trigger signal in the case of pulse width control is shown in FIG. 2 as a second embodiment. Again,
Similarly, a trigger signal having a constant period can be used.

[0007]

As described above, according to the present invention, an isosceles triangular triangular wave having the same inclination angle on both sides is used as the power supply voltage. In the driving method of selecting, a trigger signal having a constant period can be used even when line inversion driving is performed, which has an effect that the trigger circuit is relatively simple.

[Brief description of the drawings]

FIG. 1 is a diagram showing a drive voltage waveform and a trigger signal waveform according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a trigger signal waveform according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a voltage-luminance characteristic of a liquid crystal display and a driving voltage waveform and a trigger signal waveform in a conventional driving method .

FIG. 4 is a diagram showing a conventional drive voltage waveform and a trigger signal waveform.

Claims (2)

(57) [Claims] When a multi-gradation display of a liquid crystal display is performed, an arbitrary voltage necessary for the multi-gradation display is obtained by applying a trigger to a voltage that changes at a constant cycle with time at an arbitrary timing. Driving method characterized by that
In the method , when performing the line inversion drive, the inclination angle of both sides obtained by applying an offset to the voltage changing at the constant cycle is
A method for driving a liquid crystal display, comprising using equal isosceles triangular triangular waves. 2. When performing multi-tone display on a liquid crystal display, a trigger is applied at an arbitrary timing to a power supply voltage that changes at a constant cycle depending on time, so that an arbitrary voltage required for the multi-tone display can be obtained. In the driving method characterized by taking out, when performing line inversion driving, when an isosceles triangular triangular wave having the same inclination angle on both sides is used as a power supply voltage, when the midpoint of the voltage fluctuation amount of the triangular wave is connected, this line A method for driving a liquid crystal display, characterized in that a triangular waveform is set so that the cut-off time coincides with the one-line display time and the voltage at the midpoint coincides with the offset voltage of the voltage applied to the opposite electrode of the liquid crystal.