KR20000066522A - Method of Driving for Plasma Addressed Liquid Crystal Display - Google Patents

Abstract

PURPOSE: A method for driving a plasma address liquid crystal display is provided to prevent a mis-discharge and abnormal discharge, and reduce a frequency of a driving pulse. CONSTITUTION: The driving method for a plasma address LCD which applies a pulse having a predetermined voltage level to a negative and positive electrodes. A scanning pulse is alternately applied to the negative and positive electrodes every horizontal period. The positive electrode and the negative electrode are changed according to the scanning pulse. Thereby, a mis-discharge and abnormal discharge are prevented, and a frequency of a driving pulse is reduced.

Description

{Method of Driving for Plasma Addressed Liquid Crystal Display}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a flat panel display, and more particularly, to a method of driving a plasma address liquid crystal display for preventing mis-discharge and miss discharge.

Recently, a liquid crystal display (hereinafter referred to as "LCD"), a field emission display (hereinafter referred to as "FED") and a plasma display panel (hereinafter referred to as "PDP") Such flat display devices are being actively developed. Among them, a plasma address liquid crystal display device (hereinafter referred to as " PALC ") and a PDP are attracting attention because they have excellent brightness and image quality and are advantageous for being larger than 40 inches.

Referring to FIG. 1, a PALC according to the related art includes a backlight unit, a plasma unit, and a liquid crystal unit. PALC uses plasma discharge like PDP, but differs from PDP in discharge conditions. The biggest difference is that the discharge area is different in size. For example, the discharge area of the PDP is the pixel area and the discharge area of the PALC is the scan line area. That is, it can be seen that the discharge area of the PALC is thousands of times larger than the discharge area of the PDP. As such, since PALCs generate discharges per scan line, it is very important to generate uniform and stable discharges. Detailed description thereof will be described later.

The backlight unit 10 supplies light beams to the plasma unit and the liquid crystal unit. In addition, the plasma unit may include a first polarizing plate 22 attached to the lower substrate 24 to face the backlight unit 10, an anode A and a cathode K formed side by side on the lower substrate 24, and A barrier rib 34 is formed vertically on the lower substrate 4 to separate respective discharge channels, and an insulating film 36 is formed on the barrier rib 34. In one discharge channel, a pair of anodes (A) and cathodes (K) are arranged and filled with discharge gases such as He and Ne. The plasma unit serves as a switch element for changing the arrangement of the liquid crystal using the virtual electrode formed by the plasma discharge. In other words, the plasma unit performs a function of a switch element that is the same as a thin film transistor (“TFT”) of an LCD. Meanwhile, the liquid crystal module includes a liquid crystal layer 26 formed on the insulating film 36, a transparent electrode (ITO) 38 formed on the liquid crystal layer 26, and a color filter formed on the transparent electrode 38. A color 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 horizontal or vertical polarization characteristics of the light beam. In addition, the liquid crystal layer 26 adjusts the transmission amount of the light beam in response to an image signal applied according to the capacitance partial pressure ratio of the insulating layer 36 and the liquid crystal layer 26. At this time, a color filter 28 of red (hereinafter referred to as "R"), green (hereinafter referred to as "G"), and blue (hereinafter referred to as "B") is disposed on the transparent electrode 38. ) Is formed to achieve the desired color.

Meanwhile, the operation principle of the PALC will be described in detail with reference to FIG. 2. As shown in FIG. 2, when 0 V is applied to the anode A disposed in the discharge channel and −350 V is applied to the cathode K, plasma discharge occurs. In this case, inside the discharge channel, the charged particles 42 formed by plasma discharge have the anode potential except for the periphery of the cathode k. Accordingly, the plasma switch 44 is turned on to form a virtual electrode 40 in which the anode A is electrically shorted. That is, when plasma discharge occurs, the virtual electrode 40 is formed to have a short state with respect to the anode A. FIG. On the other hand, when the plasma discharge is completed, since the plasma switch 44 is turned off and the virtual electrode 40 is not formed, the plasma switch 44 is open to the anode. In addition, when an image signal is applied to the transparent electrode 38 during the discharge period (that is, when the virtual electrode is formed), the potential difference due to the capacitance partial ratio of the insulating layer 36 and the liquid crystal layer 26 is changed to the liquid crystal layer 26. To occur to change the arrangement of the liquid crystal to control the transmission amount of the light beam. As such, the plasma discharge inside the discharge channel performs a switching operation, and as a result, controls the light beam transmission amount of the liquid crystal unit. In other words, the plasma portion of the PALC performs the same function as the TFT of the LCD. In addition, since the state is maintained in the discharge channel even in the non-selection period after the discharge is completed, the state of the liquid crystal can be memorized. Accordingly, the PALC displays the screen corresponding to the image signal by changing the arrangement of the liquid crystal using the virtual electrode 40 formed by the plasma discharge.

3 and 4, the conventional PALC driving will be described.

Referring to FIG. 3, a conventional PALC driving device includes a cathode driving unit 52 for driving a cathode k by sequentially applying a driving voltage. Commonly connected anode A and a current limiter 56 for limiting the amount of current between anode A and cathode k during plasma discharge to prevent overcurrent are provided. Scan pulses having a predetermined voltage level (eg, Va) are applied to the first to nth cathodes k1 to kn and the common connected anode A. FIG. In addition, a resistor 54 for limiting current is connected to each cathode line. In addition, a current limiter 56 is connected between the cathode driver 52 and the driving voltage source Vk to limit the amount of current between the anode a and the cathode during plasma discharge to prevent overcurrent.

4, there is shown a diagram for explaining a conventional PALC driving method. When the switch S shown in FIG. 3 is turned on, a pulse having a positive voltage level (for example, Va) is applied to the anode a during the first horizontal period H1, and also to the first cathode k1. A pulse with a positive voltage level (eg Va) is applied. In this case, the voltage difference between the positive electrode a and the first negative electrode k1 becomes " 0 " during the period H1. In addition, after a predetermined time elapses from a rising time or falling time of the pulse of the first cathode k1, a high voltage pulse Vk having a negative voltage level is applied to the first cathode, thereby causing plasma discharge. Will be performed. On the other hand, a pulse having a positive voltage level (for example, Va) is applied to the anode a during the second horizontal period H2, and a positive voltage level (for example, Va) is applied to the second cathode k2. Pulses are applied. In this case, the potential difference between the second anode a2 and the second cathode k2 becomes "0V" during the H2 period. In addition, after a predetermined time elapses from a rising time or falling time of the pulse of the first cathode k1, a high voltage pulse Vk having a negative voltage level is applied to the first cathode, thereby causing plasma discharge. Will be performed. In addition, the driving pulse is applied in the same manner as described above during the third to nth horizontal periods to display an image corresponding to one frame.

As described above, in the conventional PALC driving method, plasma discharge can be performed only by applying a high voltage to the one electrode (eg, the cathode) by applying a high voltage pulse (Vk). As a result, excessive space charges are accumulated in the cell space, and thus driving voltages vary from line to line, resulting in a problem in that false discharge and miss discharge occur.

Accordingly, it is an object of the present invention to provide a plasma address liquid crystal display driving method for preventing mis-discharge and miss discharge.

1 illustrates a conventional PALC structure.

2 is a view for explaining the operation principle of the PALC.

3 is a view showing a conventional PALC driving device.

4 is a view illustrating a conventional PALC driving method.

5 is a view showing a PALC drive device of the present invention.

6A and 6B are diagrams for explaining the PALC driving method of the present invention.

<Description of the code | symbol about the principal part of drawing>

10: backlight 22, 32: polarization filter

24: lower substrate 26: liquid crystal

28: color filter 30: upper substrate

34: partition 36: insulating film

38: transparent electrode 40: virtual electrode

42: charged particle 44: plasma switch

52,62: cathode drive 54,64: resistance

56,66: current limiter 68: anode drive unit

In order to achieve the above object, the plasma address liquid crystal display driving method of the present invention is driven by alternately applying scanning pulses to the cathode and the anode every horizontal period.

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

A preferred embodiment of the present invention will be described with reference to FIGS. 5 to 6.

Referring to FIG. 5, the plasma address liquid crystal display driving device of the present invention includes a cathode driving part 62 for driving a cathode k by sequentially applying a driving voltage. Commonly connected anode A and a current limiter 66 for preventing overcurrent by limiting the amount of current between anode A and cathode k during plasma discharge. The first to nth cathodes k1 to kn are connected to the cathode driver 62, and the anode a is commonly connected. Further, each cathode line is connected with a first current limiting resistor 64a for limiting current, and each anode line is connected with a second current limiting resistor 64b for limiting current. In addition, the first and second current limiters 66a and 66b are connected to the cathode driver 62 and the anode driver 68 to limit the amount of current between the anode a and the cathode k during plasma discharge, thereby preventing overcurrent. Will be prevented.

Referring to FIG. 6, there is shown a diagram for explaining a method of driving a plasma address liquid crystal display device of the present invention. 6A will be described with reference to PALC driving method in the odd field. During the first horizontal period H1, the anode and scan pulses are supplied to the first anode a1 to become the cathode, and only the anode pulse is supplied to the first cathode k1 to become the anode. In detail, the anode pulse having a predetermined voltage level (eg, Va) is applied to the first anode a and the first cathode k1 during the first horizontal period H1. At this time, the voltage difference between the first anode a1 and the first cathode k1 becomes "0" during the H1 period. In addition, during the high level period of the positive electrode pulse, the positive electrode driver 68 applies a scanning pulse Vk having a negative voltage level to the first positive electrode a1 to perform plasma discharge on the corresponding scan line. In this case, a negative scanning pulse is applied to the first anode A1 and used as the cathode, and the first cathode k1 is used as the anode. During the second horizontal period H2, only the anode pulse is supplied to the second anode a2 to become the anode, and the cathode and scan pulses are supplied to the second cathode k2 to become the cathode. In detail, a pulse having a predetermined voltage level (for example, Va) is applied to the second anode a2 and the second cathode k2 during the second horizontal period H2. At this time, the voltage difference between the second positive electrode a2 and the second negative electrode k2 becomes "0V" during the H2 period. Further, while the pulse of the second cathode k2 has a base level (that is, 0V), the scan driver Vk applies a scanning pulse Vk having a negative voltage level to the second cathode k1 at the cathode driver 62 to scan the corresponding voltage. Plasma discharge is performed on the line. In this case, a negative scanning pulse is applied to the second cathode k2 to serve as the cathode, and the second anode a2 is used as the anode. In addition, during the third to n-th horizontal periods, the anode driving unit 68 sequentially applies the scanning pulses to the third to n-th anodes to perform plasma discharge on the corresponding scan lines. In addition, during the fourth to nth horizontal periods, scanning pulses are sequentially applied to the fourth to nth cathodes in the cathode driver 62 to perform plasma discharge on the corresponding scan lines. This process is performed to display an image corresponding to one frame. In other words, the space charge accumulated in the discharge cells is removed by alternately acting as the anode and the cathode every horizontal period. As a result, the driving frequency for the scanning pulse is reduced by twice as much as before, and thus it is possible to drive the integrated circuit (hereinafter referred to as "IC") at low frequency.

In addition, the method of driving the PALC in the even field will be described with reference to FIG. 6B. During the first horizontal period H1, the anode and scan pulses are supplied to the first cathode K1 to become the cathode, and only the anode pulse is supplied to the first anode A1 to become the anode. During the second horizontal period H2, only the anode pulse is supplied to the second cathode K2 to become the anode, and the anode and scan pulses are supplied to the second anode A2 to become the cathode. During the H3 to Hn horizontal periods, a driving pulse is applied in the same manner as above to display an image corresponding to one frame. That is, in the even field, the driving is reversed as in the odd field. Accordingly, the PALC driving method of the present invention causes the cathode and the anode to change every horizontal period, thereby preventing the accumulation of space charge in the discharge cell. This prevents mis-discharge and miss discharge. In addition, the driving frequency can be lowered by applying the scanning pulse to both electrodes.

As described above, the driving method of the plasma address liquid crystal display device of the present invention has the advantage of preventing mis-discharge and miss discharge and lowering the frequency of the driving pulse.

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.

Claims (3)

A plasma address liquid crystal display device driving method for applying a pulse having a predetermined voltage level to an anode and a cathode, And driving pulses alternately by applying scanning pulses to the cathode and the anode every horizontal period. The method of claim 1, And the cathode and the anode are interchanged with each other in response to the scanning pulse. The method of claim 1, The plasma address liquid crystal display driving method of the plasma discharge is divided into the odd field and the even field to drive opposite to each other.