JPH11352458A - Driving method of liquid crystal panel and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method of a liquid crystal display panel and a liquid crystal display device with a little rush current low power consumption, and without unevenness of brightness between blocks and decrease in contrast. SOLUTION: When a liquid crystal panel is driven by dividing it to a block a and a block b, alternation timings are varied between the block a and the block b by making the timings of a load signal (a) of the block a and a load signal (b) of the block b differ from each other for each period. In such a manner, the analog current waveforms are phase-shifted each other in the block a and the block b and the rush current is decreased, and since the phases are varied for each period, write times are averaged and an image display is balanced well in the block a and the block b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a liquid crystal panel used as a display device of a video device such as a television or an information device such as a computer, and a liquid crystal display device.

[0002]

2. Description of the Related Art As a conventional driving method of a liquid crystal panel and a liquid crystal display device, for example, the one described in Japanese Patent Application Laid-Open No. 5-249925 is known. FIG. 2 shows a block diagram of a conventional liquid crystal panel driving method and a liquid crystal display device. In the figure, reference numeral 10 denotes a liquid crystal panel for displaying information such as characters, and each pixel includes an a block 20a and a b block 2
0b. 11, a source electrode a of the a block, 12 a source electrode b of the b block, 13 a source IC for driving the source electrode a11 or the source electrode b12,
14 is a gate electrode, 15 is a gate IC for driving the gate electrode 14, 16 is a gate array, 17 is a control signal line of a load signal LDa for writing to the liquid crystal of the a block, and 18 is a write for the liquid crystal of the b block. A control signal line for the load signal LDb to be executed, 19 is an analog power supply
(AVDD), Ia is the analog current flowing through block a, Ib
Indicates an analog current flowing in the b block.

FIG. 3 shows a driving method of this conventional liquid crystal panel and a signal waveform diagram of a liquid crystal display device. In the figure,
(A) shows a drive waveform in block a, Vsa is a source electrode drive signal, Vg is a gate electrode signal, Vcom is a counter electrode signal, 1V is one vertical scanning period, 1H is one horizontal scanning period,
Ta indicates that the gate electrode signal Vg becomes High and the source electrode signal V
The on-period for writing sa in the liquid crystal is shown. FIG. 6B shows a drive waveform in the b block, where Vsb is a source electrode drive signal, Vg is a gate electrode signal, Vcom is a counter electrode signal, Tb is a gate electrode signal Vg becomes High, and the source electrode signal Vsb is a liquid crystal. Shows an ON period for writing data to each of them. Ia shown in FIG. 4C is a current waveform flowing from the analog power supply AVDD in the block a, and Ia shown in FIG.
b is a current waveform flowing from the analog power supply AVDD in the b block, and Itotal shown in FIG.
The waveforms of the flowing currents are shown.

The operation of the conventional liquid crystal display device having the above-described configuration will be described below with reference to FIGS.

First, in the block a, the ON period becomes the period Ta due to the load signal LDa constituted by the gate array 16, and an image is displayed on the liquid crystal panel 10. Similarly, in the block b, the ON period becomes Tb due to the load signal LDb formed by the gate array 16, and an image is displayed on the liquid crystal panel 10. The current waveform at that time is Ia shown in FIG. 3C for the block a, and Ib shown in FIG. 3D for the block b. Overall, the analog power supply (A
VDD) 19 is the total current shown in FIG.
And the inrush current is reduced.

[0006]

However, in the above configuration, the peak current is reduced in total,
For this purpose, there must be a certain time difference between the ON period Ta of the a block and the ON period Tb of the b block. Therefore, the on-period of the b-block is always shorter than that of the a-block, and writing to the liquid crystal panel becomes more severe.
There have been problems such as uneven brightness between blocks and a decrease in contrast.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method of driving a liquid crystal display panel and a liquid crystal display device, which have a small rush current and do not cause uneven brightness or contrast between blocks.

[0008]

The present invention has the following configuration to achieve the above object.

That is, a method of driving a liquid crystal panel according to the present invention is a method of driving a liquid crystal panel by dividing the liquid crystal panel into at least two blocks, wherein an alternating timing of a driving voltage applied to each block of the liquid crystal panel is set. , Each block and each period.

Further, the liquid crystal display device of the present invention is a liquid crystal display device having a liquid crystal panel which is divided and driven into at least two blocks, and a plurality of driving means for driving each block of the liquid crystal panel. The alternating voltage of each drive voltage of the liquid crystal panel output from each drive means is different for each drive means and for each cycle.

According to the present invention, the alternating timing of the drive voltage applied to each block of the liquid crystal panel is determined for each block by:
Since the difference is made in each cycle, it is possible to realize a driving method of a liquid crystal display panel and a liquid crystal display device which have a small inrush current, low power consumption, and are free from uneven brightness and low contrast between blocks.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a block diagram of a liquid crystal panel driving method and a liquid crystal display device according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a liquid crystal panel for displaying information such as characters, and each pixel is divided into an a block 20a and a b block 20b. 11 is a source electrode a of the a block, 12 is a source electrode b of the b block, 13 is a source IC for driving the source electrode a11 or the source electrode b12, 14 is a gate electrode, 15 is a gate IC for driving the gate electrode 14, 16 Is a gate array, 17 is a control signal line of a load signal LDa for writing to the liquid crystal of the a block, 18 is a control signal line of a load signal LDb for writing to the liquid crystal of the b block, 19 is an analog power supply (AVDD), Ia indicates an analog current flowing in the a block, and Ib indicates an analog current flowing in the b block. As described above, the basic configuration is the same as the conventional configuration, and the components having the same functions are given the same numbers.

FIG. 1 shows a driving method of a liquid crystal panel of the present invention and a signal waveform diagram of a liquid crystal display device. In the figure, (A)
Represents a drive waveform in block a, Vsa represents a source electrode drive signal, Vg represents a gate electrode signal, Vcom represents a counter electrode signal,
1V indicates one vertical scanning period, 1H indicates one horizontal scanning period, and Ta indicates an on period for writing the source electrode signal Vsa to the liquid crystal when the gate electrode signal Vg becomes High. FIG. 7B shows a drive waveform in the b block, where Vsb is a source electrode drive signal, Vg is a gate electrode signal, Vcom is a counter electrode signal, Tb is a gate electrode signal Vg becomes High, and the source electrode signal Vsb is a liquid crystal. Shows an ON period for writing data to each of them. Ia shown in FIG. 4C is a current waveform flowing from the analog power supply AVDD in the block a, and Ib shown in FIG.
Indicates a current waveform flowing from the analog power supply AVDD in the b block, and Itotal shown in FIG. 10E indicates a current waveform flowing from the analog power supply AVDD. in this way,
This is the same as the conventional configuration, and the same number is assigned.

The operation of the liquid crystal display device of the present embodiment configured as described above will be described below with reference to FIGS.

First, in the block a, the ON period becomes the period Ta due to the load signal LDa constituted by the gate array 16, and an image is displayed on the liquid crystal panel 10. Similarly, in the block b, the ON period becomes Tb due to the load signal LDb formed by the gate array 16, and an image is displayed on the liquid crystal panel 10. The current waveform at that time is Ia shown in FIG. 3C for the block a, and Ib shown in FIG. 3D for the block b. Overall, the analog power supply (A
VDD) 19 is the total current shown in FIG.
become that way. As described above, the peak current of the analog power supply is reduced in total by shifting the timing of the alternating between the a block and the b block.

In this embodiment, the AC writing timing is changed to Ta and Tb every 1 V cycle, so that the writing time to the liquid crystal panel is balanced between the a block and the b block. According to this, it is possible to make the writing time in the a-block and the b-block substantially equal by changing the alternating-current timing every cycle of 1V. Thus, problems such as uneven brightness between blocks and a decrease in contrast do not occur.

In the above embodiment, two liquid crystal panels are used.
Although it is divided into blocks, it may be divided into three, four, or more and driven.

Although the liquid crystal panel is divided and driven in blocks, the liquid crystal panel may be similarly divided and driven inside the source IC.
At that time, the same effect as that of the present invention is generated and driven inside the IC, and the same effect can be obtained.

[0020]

As described above, according to the present invention,
Thus, it is possible to realize a liquid crystal display panel driving method and a liquid crystal display device that have a small inrush current, low power consumption, and are free from uneven brightness and low contrast between blocks.

[Brief description of the drawings]

FIGS. 1A and 1B are a driving waveform diagram and a current waveform diagram of a liquid crystal panel driving method according to an embodiment of the present invention, wherein A is a panel driving waveform in an a block, B is a panel driving waveform in a b block, and C is an a block. Is a current waveform flowing from the analog power supply AVDD, D is a current waveform flowing from the analog power supply AVDD in the b block, and E is an analog power supply.
Current waveforms flowing from AVDD are shown.

FIG. 2 is a block diagram of a driving method of the present invention and a conventional liquid crystal panel and a liquid crystal display device.

3A and 3B are a drive waveform diagram and a current waveform diagram of a conventional method of driving a liquid crystal panel, wherein A is a panel drive waveform in a block, B is a panel drive waveform in b block, and C is an analog power supply AVDD in a block. D indicates a current waveform flowing from the analog power supply AVDD in the block b, and E indicates a current waveform flowing from the analog power supply AVDD.

[Explanation of symbols]

Reference Signs List 10 liquid crystal panel 11 source electrode a of block a 12 source electrode b of block b 13 source IC for driving source electrode a or source electrode 14 gate electrode 15 gate IC for driving gate electrode 16 gate array 17 to liquid crystal of block a Control signal line of load signal LDa for writing data to block 18 Control signal line of load signal LDb for writing data to block b of liquid crystal 19 Analog power supply (AVDD) 20a a block 20b b block

Claims (2)

[Claims] 1. A method for driving a liquid crystal panel by dividing the liquid crystal panel into at least two blocks, the method comprising:
A driving method for a liquid crystal panel, wherein the driving method is different for each block and for each cycle. 2. A liquid crystal display device comprising: a liquid crystal panel driven to be divided into at least two blocks; and a plurality of driving means for driving each block of the liquid crystal panel.
A liquid crystal display device, characterized in that the timing of AC conversion of each driving voltage of the liquid crystal panel output from each of the driving means is different for each of the driving means and for each cycle.