JPH05249925A - Liquid crystal panel driving method and liquid crystal display - Google Patents

Abstract

PURPOSE:To heighten operational stability by making alternating current converting timings of respective driving voltage impressed upon respective liquid crystal panel groups different from each other with the respective groups to divisionally driven liquid crystal panels. CONSTITUTION:Though driving ON-voltage 16 and OFF-voltage 17 change according to picture elements and data, bias voltage 18 is impressed simultaneously upon the whole picture elements except in a selected single line, so that a rush current is flowed into the bias voltage 18 to liquid crystal panels as shown by waveform charts 13 and 14 when polarity of the driving voltage for alternating current converting timings are set to be dislocated from each other in the upper half and in the lower half. Thereby, as for an electric current of the bias voltage 18, since peak positions of the rush current are dislocated from each other, the maximum value of the rush current can be reduced to about half in an electric power supply line of the bias voltage 18 as compared with a conventional value as shown by a wave form chart 15.

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 useful as a display device of a video device such as a television and an information device such as a computer, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A conventional liquid crystal panel driving method and liquid crystal display device are shown in, for example, "Liquid Crystal / Applied Edition: Mitsuharu Okano and Shunsuke Kobayashi (Baifukan)", multiple electrode simultaneous scanning method [P99 to P100]. Has been done.

FIG. 5 is a schematic block diagram showing an electrode structure of a liquid crystal panel and a drive circuit in a conventional two-division drive liquid crystal display device. The liquid crystal display device is provided with a simple matrix type liquid crystal panel 50 for displaying information such as characters, and the liquid crystal panel 50 has a signal electrode 51 and a scanning electrode 52 for operating the liquid crystal panel 50. Pixels are formed at the intersections of the two divided upper and lower regions of 50. The two sets of signal electrodes 51 are connected to signal drivers 53a and 53b that drive them, respectively, and the two sets of scan electrodes 52 are connected to scan drivers 54a and 54b that drive them, respectively. The display data 55a corresponding to the upper half, the alternating signal 56, the synchronization signal group 57, the data clock 58, and the liquid crystal drive voltage group 59 including the bias voltage are connected to the signal driver 53a, and the lower half is connected to the signal driver 53b. Corresponding to the display data 55b, alternating signal 56, synchronization signal group 57, data clock 58, liquid crystal drive voltage group 5
9 is connected. An AC signal 56, a sync signal group 57, and a liquid crystal drive voltage group 59 are connected to the scan drivers 54a and 54b.

The operation of the conventional liquid crystal display device having the above structure will be described below. In FIG. 5, the display data 55a and 55b are simultaneously transferred to the upper and lower signal drivers 53a and 53b in synchronization with the data clock 58. The upper and lower scan drivers 54a and 54b simultaneously scan the upper and lower sides of the liquid crystal panel 50 in response to the synchronization signal, and sequentially display the upper and lower panels simultaneously by the drive signals of the signal drivers 53a and 53b. At this time, AC signal 5
6 is supplied to all the drivers at the same time, the polarity of the drive voltage applied to the liquid crystal panel 50 is inverted in synchronization with the alternating signal 56, and the liquid crystal panel 50 is AC driven.

FIG. 6 is a drive voltage waveform diagram and a bias voltage of the liquid crystal panel 5 in the conventional method of driving the liquid crystal panel 50.
It is a current waveform diagram which flows into 0. In FIG. 6, (61)
Is a drive voltage waveform diagram applied to the pixels of the liquid crystal panel 50 in the upper half, and (62) is a drive voltage waveform diagram in the lower half, showing the case where alternating current is applied at the frame period. (63) is a current waveform diagram of the bias voltage on the power supply line, 64 is an ON voltage, 65 is an OFF voltage, and 66 is a bias voltage.

[0006]

However, in the above configuration, as shown in (63) of FIG. 6, when the polarity inversion is performed for AC conversion, the bias voltage applied to all pixels is changed. The polarity of is reversed all at once, and an inrush current flows through the liquid crystal panel capacitance. Therefore, there is a problem in that the power supply line is disturbed by this inrush current and the operation of the driver becomes unstable.

The present invention considers the above-mentioned conventional problems and reduces the inrush current at the time of polarity reversal.
An object of the present invention is to provide a driving method of a liquid crystal panel and a liquid crystal display device having high operation stability.

[0008]

According to a first aspect of the present invention, for a liquid crystal panel which is divided and driven into at least two groups, an AC conversion timing of each drive voltage applied to each group of the liquid crystal panel is set, This is a liquid crystal panel driving method that is different for each group.

According to a second aspect of the present invention, a liquid crystal panel is divided and driven into at least two groups, a plurality of driving means for driving each group of liquid crystal panels, and each driving of the liquid crystal panel output from each driving means. A liquid crystal display device is provided with each drive means, or a control means for controlling a signal in a front stage or a signal in a rear stage so that the AC conversion timing of the voltage is different for each drive means.

According to a third aspect of the present invention, for a liquid crystal panel that is driven to be divided into at least two groups, the alternating polarity of each drive voltage applied to each group of the liquid crystal panel is set to at least one group. This is a method of driving a liquid crystal panel having the opposite polarity to the other groups.

According to a fourth aspect of the present invention, a liquid crystal panel is divided and driven into at least two groups, a plurality of driving means for driving each group of liquid crystal panels, and each driving of the liquid crystal panel output from each driving means. The polarity of alternating voltage is
It is a liquid crystal display device provided with each drive means or a control means for controlling a signal in a front stage or a signal in a rear stage so that at least one group has a polarity opposite to that of another group.

[0012]

According to the first and second aspects of the present invention, since the alternating current timing of each drive voltage is different for each group of liquid crystal panels, the polarity inversion of the drive voltage does not occur all at once, and therefore the maximum inrush current can be obtained. The value is reduced to a fraction.

According to the present invention of claims 3 and 4, since the polarity of at least one group of the drive voltage for alternating current is opposite to the polarity of the other groups, the polarity of the liquid crystal panel is improved. The polarities of the inrush currents are also reversed, and the currents of at least one group cancel each other and the currents of the other one group, so that the inrush current flowing through the power supply line can be apparently reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 shows a drive voltage waveform diagram and a bias voltage current waveform diagram of a method of driving a liquid crystal panel according to an embodiment of the present invention. That is, FIG. 1 shows the case where the liquid crystal panel is driven in two divisions, and the alternating period is driven at the frame period.
2) is a drive voltage waveform diagram of pixels in the upper and lower halves, (13) and (14) are current waveform diagrams of bias voltage to the liquid crystal panels in the upper and lower halves, respectively, and (15) is a bias voltage 16 is an ON voltage, 17 is an OFF voltage, and 18 is a bias voltage.

The operation of the driving method of the liquid crystal panel of this embodiment constructed as described above will be described below.
In FIG. 1, the drive ON voltage 16 and the OFF voltage 17 change depending on the pixel and the data, but the bias voltage is applied simultaneously to all the pixels other than the selected one line. When the polarity of the drive voltage is reversed, an inrush current flows in the bias voltage to the liquid crystal panel as shown in waveform diagrams (13) and (14). However, because the timing of alternating current is shifted in the upper half and the lower half,
Since the peak position of the inrush current of the bias voltage current is shifted, the maximum value of the inrush current can be reduced to about half of the conventional value as shown in the waveform chart (15) in the bias voltage power supply line.

FIG. 2 is a block diagram showing the structure of a liquid crystal display device according to an embodiment of the present invention. That is, the liquid crystal display device is provided with a simple matrix type liquid crystal panel 20 for displaying information such as characters, and the liquid crystal panel 20 has signal electrodes 21 and scanning electrodes 22 for operating the liquid crystal panel 20, The two upper and lower regions of the liquid crystal panel 20 are arranged orthogonally to each other, and pixels are formed at their intersections. The two sets of signal electrodes 21 are
Signal drivers 23a and 23b for respectively driving them
, And the two sets of scan electrodes 22 are connected to scan drivers 24a and 24b for driving them. The display data 25a corresponding to the upper half, the alternating signal 26, the control signal group 27, and the liquid crystal driving voltage group 28 such as a bias voltage are connected to the signal driver 23a, and the scan driver 24a includes the alternating signal 26 and the control signal. A signal group 27 and a drive voltage group 28 are connected. The display data 25b corresponding to the lower half, the AC signal 26 via the delay circuit 29 for delaying the signal for a predetermined time, the control signal group 27, and the drive voltage group 28 are connected to the signal driver 23b, and the scan driver 24b is connected to the scan driver 24b. , The alternating signal 26 via the delay circuit 29,
A control signal group 27 and a drive voltage group 28 are connected.

Further, the signal electrode 21, the scanning electrode 22, and the
Signal drivers 23a and 23b, scan drivers 24a and 2
4b constitutes a driving means, and the delay circuit 29 constitutes a control means.

The operation of the liquid crystal display device of the above embodiment having the above-described structure will be described below. In FIG. 2, the data 25a and the data 25b are simultaneously transferred to the upper and lower signal drivers 23a and 23b, respectively, and the signal drivers 23a and 23b and the scanning drivers 24a and 24b are synchronized with the respective signals of the control signal group 27 and the upper and lower signals. Drive panels simultaneously. The delay circuit 29 delays the timing of the AC signal 26 and supplies it to the drive system of the lower half, and makes the polarity inversion timing for AC conversion of the liquid crystal panel of the lower half different from that of the upper half. As a result, as shown in FIG. 1, the inrush current generated at the time of polarity reversal can be reduced to about half.

FIG. 3 shows a drive voltage waveform diagram and a bias voltage current waveform diagram of a method for driving a liquid crystal panel according to another embodiment of the present invention. FIG. 3 shows a case where the liquid crystal panel is driven in two, as in FIG. 1, and (31) and (32) are drive voltage waveform diagrams of pixels in the upper half and the lower half, respectively.
3) and (34) are current waveform diagrams of the bias voltage to the liquid crystal panels in the upper and lower halves, respectively, and (35) is a current waveform diagram of the power supply line of the bias voltage.

As is apparent from FIG. 3, a rush current flows in the bias voltage with respect to the liquid crystal panel each time the polarity of the drive voltage is reversed, but the polarity of the drive voltage for alternating current is reversed vertically. Since the current waveforms of the bias voltage to the liquid crystal panel have opposite polarities as shown in the waveform diagrams (33) and (34), they are canceled in the bias power supply line as shown in the waveform diagram (35). Almost no inrush current flows.

FIG. 4 is a block diagram showing the structure of a liquid crystal display device according to another embodiment of the present invention. That is, the liquid crystal display device is provided with a simple matrix type liquid crystal panel 40 for displaying information such as characters, and the liquid crystal panel 4 is provided.
0 is a signal electrode 4 for operating the liquid crystal panel 40.
1 and the scanning electrode 42 are arranged orthogonally to the upper and lower regions of the liquid crystal panel 40 which are divided into two, and pixels are formed at the intersections thereof. The two sets of signal electrodes 41 are connected to signal drivers 43a and 43b that drive them, respectively, and the two sets of scanning electrodes 42 are connected to scan drivers 44a and 44b that drive them, respectively. The signal driver 43a has display data 45 corresponding to the upper half.
a, an AC signal 46, a control signal group 47, and a liquid crystal drive voltage group 48 such as a bias voltage are connected to the scan driver 44.
An alternating signal 46, a control signal group 47, and a drive voltage group 48 are connected to a. In the signal driver 43b, the display data 45b corresponding to the lower half, the alternating signal 46 via the inverting circuit 49 for inverting the polarity of the signal, and the control signal group 4 are provided.
7, a drive voltage group 48 is connected, and an AC signal 46, a control signal group 47, and a drive voltage group 48 are connected to the scan driver 44b via an inverting circuit 49.

Further, the signal electrode 41, the scanning electrode 42,
Signal drivers 43a and 43b, scan drivers 44a and 4
4b constitutes a driving means, and the inverting circuit 49 constitutes a control means.

The operation of the liquid crystal display device of the above embodiment having the above-mentioned structure will be described below. The upper and lower liquid crystal panels are simultaneously driven as in the case shown in FIG. 2, but the AC signal 46 is logically inverted by the inversion circuit 49 and supplied to the lower half drive circuits 43b and 44b. Therefore, the polarities of the drive voltages for driving the upper and lower liquid crystal panels have opposite polarities as shown in FIG. 3, and the inrush current of the bias voltage flowing into the liquid crystal panel has opposite polarities at the upper and lower sides, so that the two cancel each other out. Almost no inrush current flows through the bias voltage power supply line.

In any of the embodiments of the driving method of the liquid crystal panel, the driving voltage waveforms of FIGS. 1 and 3 are merely examples, and the present invention is not limited to this.

Further, in the above embodiment, all the liquid crystal panels are simple matrix liquid crystals, but the present invention is not limited to this.

In each of the above embodiments, the liquid crystal panel is divided into two parts, that is, upper and lower parts (in the drawing), but the invention is not limited to this, and three or four parts may be used. Of course, the driving may be performed so as to be divided into the right side (on the drawing) and the like.

Further, in the above embodiment, as the control means,
A delay circuit is used when the alternating current timing is different, and an inverting circuit is used when the alternating current is inverted, but it goes without saying that the invention is not limited to this.

Further, in the above-mentioned embodiment, the control means controls the signal in the preceding stage of the driving means. However, the present invention is not limited to this, and the control means may control the signal in the latter stage of the driving means. Of course it is good.

[0030]

As is clear from the above description, the present invention has the advantage that the operation stability can be improved by reducing the inrush current to the liquid crystal panel at the time of polarity reversal.

[Brief description of drawings]

FIG. 1 is a drive voltage waveform diagram and a bias voltage current waveform diagram of a method for driving a liquid crystal panel according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a drive voltage waveform diagram and a bias voltage current waveform diagram of a liquid crystal panel driving method according to another embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional liquid crystal display device.

FIG. 6 is a drive voltage waveform diagram and a bias voltage current waveform diagram in a conventional liquid crystal panel driving method.

[Explanation of symbols]

 16 ON voltage 17 OFF voltage 18 Bias voltage 20 Liquid crystal panel 21, 41 Signal electrode 22, 42 Scan electrode 23a, 23b, 43a, 43b Signal driver 24a, 24b, 44a, 44b Scan driver 25a, 25b, 45a, 45b Display data 26 , 46 AC signal 27, 47 Control signal group 28, 48 Drive voltage group 29 Delay circuit 49 Inversion circuit

Claims (4)

[Claims] 1. A liquid crystal panel that is divided into at least two groups and driven, and the AC conversion timing of each drive voltage applied to each group of the liquid crystal panel is made different for each group. LCD panel driving method. 2. A liquid crystal panel which is divided and driven into at least two groups, a plurality of driving means for driving each group of the liquid crystal panel, and an AC conversion of each driving voltage of the liquid crystal panel output from each driving means. A liquid crystal display device comprising: each drive means, or a control means for controlling a signal in a front stage or a signal in a rear stage so that the timing is different for each drive means. 3. For a liquid crystal panel that is driven to be divided into at least two groups, the polarity of alternating current of each drive voltage applied to each group of the liquid crystal panel is set so that at least one group is different from other groups. And a method of driving a liquid crystal panel, which is characterized by having opposite polarities. 4. A liquid crystal panel which is divided and driven into at least two groups, a plurality of driving means for driving each group of the liquid crystal panel, and an alternating current of each driving voltage of the liquid crystal panel output from each driving means. Of each of the driving means, or a control means for controlling the signal in the preceding stage or the signal in the succeeding stage so that at least one group has a polarity opposite to that of the other groups. Liquid crystal display device.