KR100585630B1 - Method Of Driving Plasma Address Liquid Crystal Display - Google Patents

Abstract

The present invention relates to a plasma address liquid crystal display driving method for enabling high speed driving.

The plasma address liquid crystal display driving method of the present invention is characterized in that the potential of the anode is periodically varied from a positive voltage to a negative voltage.

According to the present invention, by applying a variable potential to the anode to remove unnecessary charged particles accumulated in the discharge channel early after discharge, not only can maintain stable image data, prevent crosstalk phenomenon, but also address the image signal at high speed. It becomes possible.

Description

Method of Driving Plasma Address Liquid Crystal Display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma address liquid crystal display device, and more particularly to a plasma address liquid crystal display driving method for enabling high speed driving.

Recently, Liquid Crystal Display (hereinafter referred to as LCD), Field Emission Display (FED), Plasma Display Panel (hereinafter referred to as PDP) and Plasma Address Liquid Crystal The research on flat panel displays such as displays is being actively conducted. Among these, PALC displays and PDPs are attracting attention because they have excellent brightness and image quality, and are advantageous for being larger than 40 inches. PALC displays use plasma discharge like PDP, but there are many differences from PDP in discharge conditions. The biggest difference is the size of the discharge area, where the discharge area of the PDP is the pixel area while the discharge area of the PALC display is the scan line. In other words, it can be seen that the discharge area of the PALC display is thousands of times larger than the discharge area of the PDP. Accordingly, it is important for PALC displays to obtain a uniform and stable discharge over the entire line. To this end, PALC displays require precise alignment of partitions and electrodes as well as uniform pattern manufacturing. In addition, since the PALC display does not require a large amount of discharge current, it is advantageous that the current is small in terms of lifetime and power consumption.

1 and 2, the structure of a typical PALC display is shown.

The PALC display illustrated in FIGS. 1 and 2 includes a backlight unit 10, a plasma unit, and a liquid crystal unit. The backlight unit 10 supplies light beams to the plasma unit and the liquid crystal unit. The plasma unit includes a first polarizer 22 disposed to face the backlight unit 10, a lower substrate 24 attached to the first polarizer 22, and an anode disposed side by side on the lower substrate 24. A) and a cathode C, a partition wall 34 formed on the lower substrate 24 in parallel with the electrodes A and C, and an insulating film 36 formed on the partition wall 34. The partition wall 34 separates discharge channels and provides a discharge space between the lower substrate 24 and the insulating layer 36. A pair of anodes (A) and cathodes (C) are arranged in each discharge channel divided by the partition wall 34, and discharge gas such as helium (He) and neon (Ne) is filled in the discharge space. The plasma unit performs a function similar to the switching operation of the thin film transistor (TFT) of the LCD. The liquid crystal part includes a liquid crystal layer 26 formed on the insulating layer 36, a transparent electrode ITO formed on the liquid crystal layer 26, that is, a data electrode 38, and a color filter formed on the data electrode 38. Filter 28, an upper substrate 30 formed on the color filter 28, and a second polarizing plate 32 attached to the upper substrate 30. The first and second polarizers 22 and 32 change the polarization characteristics of the light beams generated by the backlight unit 10. The liquid crystal layer 26 adjusts the transmission amount of the light beam in response to an image signal applied to the data electrode 38 according to the capacitance partial ratio of the insulating layer 36 and the liquid crystal layer 26. Red (R), green (G), and blue (B) color filters 28 are alternately formed on the data electrode 38 to be incident through the liquid crystal layer 26 and the data electrode 38. The light beam generates unique visible light.

Looking at the driving method of the PALC display having such a structure, when a voltage of about 0V to the anode (A) and -350V to the cathode (C) is applied in any discharge channel of the plasma portion, the plasma discharge occurs. During this plasma discharge period, almost all regions except the vicinity of the cathode C become the anode potential. In other words, a virtual electrode electrically shorted with the anode A is formed in the discharge channel where the plasma discharge is generated. On the other hand, virtual electrodes are not formed in the discharge channel in which the plasma discharge has not occurred, and are open to the anode A. In other words, the anode A and the virtual electrode are shorted or opened by the on / off of the plasma discharge. When the virtual electrode is formed due to the plasma discharge and an image signal is applied to the data electrode 38, electric charges are generated on the virtual electrode. As a result, a potential difference is generated between the data electrode 38 and the anode A to be applied to the insulating film 36 and the liquid crystal layer 26. For this reason, the potential difference due to the capacitance partial pressure ratio between the insulating film 36 and the liquid crystal layer 26 is applied to the liquid crystal layer 26 to change the liquid crystal array structure so that the liquid crystal layer 26 controls the transmission amount of the light beam. The electric charges generated on the virtual electrode of the discharge channel are maintained even during the non-selection period in which the discharge is stopped, thereby making it possible to memorize the liquid crystal array state of the liquid crystal layer 26. As described above, the PALC display can display an image by charging a liquid crystal using plasma. Since the liquid crystal layer 26 is not a self-luminous element, external light such as the backlight unit 10 must be irradiated. When light is irradiated, the light efficiency or brightness of the PALC display is influenced, and the alignment of the plasma discharge channel such as the electrode position and the cell structure plays an important role.

FIG. 3 shows the overall electrode arrangement structure of the PALC display shown in FIGS. 1 and 2, where a typical PALC display has n cathodes alternately arranged on the lower substrate 24 shown in FIGS. 1 and 2. (C1 to Cn) and anodes (A1 to An) and m data electrodes (D1 to Dm) disposed on the liquid crystal layer 26 to cross the cathodes (C1 to Cn) and the anodes (A1 to An). do. In addition, the partition wall 34 is formed side by side between the pair of cathodes C and A to provide discharge channels in units of scan lines. Here, the cathodes C1 to Cn and the data electrodes D1 to Dm are driven separately, while the anodes A1 to An are connected and driven in common.

FIG. 4 shows voltage waveforms for driving the PALC display shown in FIG.

In FIG. 4, when the anodes A1 to An are fixed at the ground potential and a negative voltage pulse of about -350 V is supplied to the cathodes C1 to Cn in a line unit, discharge is sequentially generated between the anode and the cathode, and each discharge channel is performed. The virtual electrode is formed inside the same as the potential of the anode. At this time, the liquid crystal layer is charged according to the image signal supplied to the data electrode, that is, the gray scale control voltage, thereby implementing the image signal (gradation). In this case, in order to prevent deterioration of the liquid crystal layer, it is preferable to reversely supply the phase of the gradation control voltage in units of scan lines or frames.

However, according to the above-described conventional driving method, DC discharge is formed during plasma discharge, and excessive space charge is accumulated in the discharge channel, causing malfunction. In addition, since most space charges are distributed only on one side of the discharge channel during plasma discharge, the decay period becomes longer, thereby causing crosstalk between adjacent scan lines. In detail, a negative voltage pulse is supplied to the nth cathode Cn to generate a plasma discharge in the nth scan line, and then the gray scale control voltage is written to adjust the arrangement state of the liquid crystal layer. Even after this writing period, the liquid crystal layer remains in that state until the next plasma discharge occurs. Subsequently, immediately after the writing period of the n th scan line ends, the next n + 1 th scan lines implement gradation in the same manner. In this case, due to the space charge accumulated in the discharge channel of the nth scan line, as shown in FIG. 5, the decay time t3 is long, and thus the discharge of the n + 1th scan line is completed before writing of the gray scale control voltage is completed. When plasma discharge occurs in a channel, crosstalk is generated between adjacent discharge channels due to the gray level control voltage of another scan line being written or an erroneous discharge occurring. It can be seen from FIG. 5 that the decay time t3 slows down due to the space charge accumulated in the discharge channel after the plasma formation period t1 and the data capture period t2.

In addition, the discharge must be turned off immediately after the discharge is generated, that is, after the positive and negative electrodes are short-circuited to remove the space charge inside the discharge channel so that the state of the data can be continuously maintained. Here, due to the space charge of the discharge channel, the high impedance state of the discharge channel may not be maintained, resulting in a decrease in the efficiency of light emission or a very low transmittance and a problem of failing fast addressing.

Accordingly, an object of the present invention is to change the potential of the anode periodically from a positive voltage to a negative voltage to quickly remove unnecessary charged particles in the discharge channel to maintain stable image data and to prevent crosstalk phenomenon. It is to provide a display driving method.

Another object of the present invention is to provide a method of driving a PALC display, which can increase an address driving speed by periodically changing an electric potential of an anode from a positive voltage to a negative voltage to quickly remove unnecessary charged particles in a discharge channel.

In order to achieve the above objects, the PALC display driving method according to the present invention is characterized in that the potential of the positive electrode is periodically varied from a positive voltage to a negative voltage.

Other objects and advantages of the present invention other than the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 6 to 8.

6 illustrates an overall electrode arrangement structure of a PALC display for applying a driving method according to an embodiment of the present invention.

In contrast to the PALC display shown in FIG. 6 and the PALC display shown in FIG. 3, the PALC display of FIG. 3 differs from one another with the partition 34 interposed therebetween as the cathode C and the anode A are alternately disposed. While polar electrodes are disposed adjacent to each other, the PALC display of FIG. 6 has electrodes of the same polarity disposed adjacent to each other with the partition 34 interposed therebetween. Accordingly, in the case of the PALC display of FIG. 3, the distance between the cathode C and the anode A disposed in one scanning line and the partition 34 is disposed between the anodes A and cathode C disposed adjacent to each other. While the same spacing results in a potential difference between the anode A and the cathode C with the partition 34 interposed therebetween, it does not fully utilize the characteristics of the discharge and causes unstable operation such as mis-discharge of the discharge channel. In the PALC display of FIG. 6, electrodes having the same polarity are disposed adjacent to each other with the partition 34 interposed therebetween so that no potential difference occurs between two electrodes having the partition 34 interposed therebetween, thereby eliminating an unstable element between adjacent discharge channels. There is an advantage that can prevent the discharge.

FIG. 7 illustrates a voltage waveform for driving the PALC display shown in FIG. 6 according to an embodiment of the present invention.

In FIG. 7, a positive voltage having a predetermined potential is periodically applied to the anode A, and a negative voltage for causing discharge in synchronization with the positive voltage is applied to the cathodes C1, C2, C3,. This is applied sequentially. In this case, by applying a predetermined amount of voltage to the anode A, it is possible to relatively reduce the voltage applied to the cathode C to cause discharge. Subsequently, a negative voltage is applied to the anode A and a voltage of 0 V is applied to the cathode during the writing period in which the image signal of one scan line, that is, the gray scale control signal, is applied to the data electrodes D1 to Dm. Accordingly, the electric potential in the discharge channel is reversed, and the charged particles in the neutral state accumulated in the discharge channel are recombined again so that the charged particles are removed early. In other words, the electrons accumulated around the anode and the ions around the cathode, that is, the charged particles are extinguished early. Accordingly, as shown in FIG. 8, the decay time t3 of the discharge channel is significantly reduced, so that the image signal can be addressed at high speed.

As described above, according to the PALC display driving method according to the present invention it is possible to significantly reduce the decay time by applying a variable potential to the anode to remove unnecessary charged particles accumulated in the discharge channel early after discharge. As a result, it is possible not only to maintain stable video data and to prevent crosstalk, but also to address video signals at high speed.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a perspective view showing a general plasma address liquid crystal display configuration.

FIG. 2 is a cross sectional view of the plasma address liquid crystal display shown in FIG. 1; FIG.

3 is an overall electrode arrangement diagram of the plasma address liquid crystal display shown in FIG.

4 is a voltage waveform diagram for driving the plasma address liquid crystal display shown in FIG.

5 is a diagram illustrating a decay time according to the driving waveform shown in FIG. 4.

6 is an overall electrode arrangement diagram of a plasma address liquid crystal display for applying the plasma address liquid crystal display driving method according to the present invention;

7 is a voltage waveform diagram illustrating a plasma address liquid crystal display driving method according to an exemplary embodiment of the present invention.

8 is a diagram illustrating a decay time according to the voltage waveform shown in FIG. 7.

<Description of Symbols for Main Parts of Drawings>

10: backlight 22, 32: polarizer

24: lower substrate 26: liquid crystal layer

28: color filter 30: upper substrate

34: partition 36: insulating film

38: transparent electrode A: anode

C: Cathode

Claims (1)

In a driving method of a plasma address liquid crystal display comprising an anode, a cathode and a data electrode, A positive voltage is supplied to the positive electrode and a negative voltage is supplied to the negative electrode to generate a discharge. And a negative voltage is supplied to the anode and an image signal is supplied to the data electrode while a zero voltage is supplied to the cathode to realize gray scale.