KR20000059301A - Plasma Address Liquid Crystal Display and Driving Method Thereof - Google Patents

Abstract

PURPOSE: A plasma address liquid crystal display device and a method for driving the same are provided to apply a driving voltages with inverse phases on the anode and cathode. CONSTITUTION: A method for driving a plasma address liquid crystal display device includes following steps. At the first step, a voltage is applied on the anode and cathode which are implemented in a discharge cell which is defined by a compartment formed in a predetermined spacing between the upper and lower substrates. At the second step, the voltage applied on the anode and cathode of the plasma address liquid crystal display device has inverse phases, respectively. The voltage may be applied on the anode and the cathode of the plasma address liquid crystal display device alternatively in a predetermined interval.

Description

Plasma Address Liquid Crystal Display and Driving Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display, and more particularly, to a plasma address liquid crystal display and a driving method thereof capable of high speed driving and low voltage driving.

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. On the other hand, since the liquid crystal is not a self-luminous element, the backlight unit 10 is used to supply external light. At this time, when the light beam is irradiated from the backlight unit 10, the light efficiency or luminance is changed by the position of the electrode and the structure of the discharge channel.

In addition, as shown in FIG. 3, a plurality of discharge channels are provided in the plasma unit between the first to n th partition walls 34a to 34n formed perpendicularly to the upper portion of the lower substrate 24. A pair of electrodes (that is, the cathode K and the anode A) is disposed in the discharge channel. The first to nth anodes a1 to an are commonly arranged in a structure connected to the ground voltage source GND. A method of driving a PALC having such an electrode structure will be described with reference to FIGS. 4 and 5.

Referring to FIG. 4, a waveform diagram of a gray level signal for implementing gray levels of a conventional PALC is illustrated. As shown in FIG. 4, the gray scale control signal is applied such that the polarity is alternately inverted based on the voltage level of the anode A. FIG. Accordingly, the phase of the gray scale control voltage is reversely supplied for each scan line or every frame to prevent deterioration of the liquid crystal layer 26. In this case, waveforms of the driving voltages applied to the cathode and the anode are shown in Figs. 5A and 5B. As shown in FIG. 5, the anode A is commonly connected to the ground voltage source GND and has a potential of 0V. When a driving voltage having a high voltage level (for example, -350 V) is applied to the cathode K, plasma discharge occurs in the discharge channel. Accordingly, in the discharge channel, the liquid crystal layer 26 is ready to be charged by the switching operation by plasma discharge. Subsequently, when the gray scale control voltage is applied, the gray scale control voltage according to the capacitance partial ratio of the insulating layer 36 and the liquid crystal layer 26 is applied to the liquid crystal layer 26 to implement gray scale.

However, a direct current (DC) discharge is formed during plasma discharge, causing excessive space charge to accumulate in the discharge channel, causing malfunction. In addition, since most space charges are distributed only on one side of the discharge channel during discharge, the decay time becomes long, and thus the amount of charge between adjacent scan lines is changed to generate crosstalk. This will be described in detail. For example, after the discharge occurs in the nth negative line Kn, the gray level control voltage having a negative voltage level is written to implement the gray level of the nth negative line. Thereafter, the liquid crystal layer 26 maintains its current state. Subsequently, after a predetermined time (that is, one vertical synchronizing time), the image is displayed by the same method in the n + 1th cathode line Kn + 1. At this time, the decay time becomes longer due to the space charge accumulated in the discharge channel, and the plasma discharge of the n + 1 cathode line Kn + 1 is completed before the gray level control voltage of the nth cathode line Kn is completed. In this case, there is a problem that crosstalk occurs between adjacent discharge channels due to the gray line control voltage of another line being written or misdischarged. Accordingly, there is an urgent need for a new plasma address liquid crystal display and a driving method thereof capable of high speed driving and low voltage driving of PALC.

Accordingly, an object of the present invention is to provide a plasma address liquid crystal display driving method capable of high speed driving and low voltage driving.

1 is a perspective view showing the structure of a conventional PALC.

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

3 is a view showing the electrode configuration of FIG.

4 is a waveform diagram showing waveforms of gray level signals for implementing gray levels of a conventional PALC.

5 is a waveform diagram showing waveforms of driving voltages applied to the anode and cathode of a conventional PALC.

6 is a view showing the electrode structure of the PALC according to the present invention.

7 is a view for explaining a method of driving a PALC according to 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

In order to achieve the above object, the plasma address liquid crystal display driving method according to the present invention applies a driving voltage of opposite phases to the cathode and the anode.

The plasma address liquid crystal display device according to the present invention includes an odd-numbered anode commonly connected to the odd-numbered anode line among anode lines, and an even-numbered anode commonly connected to the even-numbered anode line among the anode lines. do.

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.

Referring to Figures 6 and 7 will be described a preferred embodiment of the present invention.

6, the electrode structure of the PALC according to the present invention is shown. PALC according to the present invention corresponds to the _odd-numbered anode (hereinafter referred to as "a _odd ") and the even- _numbered number that commonly connect the positive (a1, a3, ??, an-1) lines corresponding to the odd number of the total anode And an _{even-numbered} anode (hereinafter referred to as “a _even ”) commonly connected to the anode (a2, a4, ??, an) lines. At this time, the driving voltage having a predetermined voltage level can be applied to the _odd-numbered anode (a _odd ) and the _{even-numbered} anode (a _even ).

Referring to FIG. 7, there is shown a diagram for describing a PALC driving method according to the present invention.

As shown in FIG. 7, positive pulses are alternately applied to the _odd-numbered anodes a _odd and _{even-numbered} anodes a _even . First, a positive pulse is supplied to the _odd-numbered anode (a _odd ) in the first vertical period, and at the same time, a negative pulse is supplied to the first cathode (k1) to discharge between the two electrodes. In this case, when an image signal is input to the data electrode (not shown), the transmittance of the liquid crystal is changed in proportion to the input voltage to implement a gray scale. In the next vertical period, a positive pulse is supplied to the _{even-numbered} anode (a _even ), and at the same time, a negative pulse is supplied to the second cathode (k2) so that a discharge occurs between the two electrodes. The transmittance of the liquid crystal is changed in proportion to this voltage to realize gray scale. In the same way, a pulse having an alternating positive voltage level is applied to the _odd-numbered anode (a _odd ) and the _{even-numbered} anode (a _even ) during the nth vertical period, and the negative voltage is sequentially applied to the first to nth cathodes. The PALC is driven by applying a pulse having a voltage level of. At this time, according to the designer's intention, the positive and negative poles may have the same magnitude and phase inverted pulses simultaneously. Accordingly, the PALC driving method according to the present invention distributes the driving voltages applied to the anode and the cathode to enable low voltage driving, and also reduces manufacturing costs by using a low voltage driving integrated circuit.

In addition, in the PALC driving method according to the present invention, since the driving voltages applied to the anode A and the cathode K have the same magnitude, the space charge is lower than the discharge of the PALC. The amount of distribution will be different. For example, when the discharge is performed by applying a voltage of 400 V to the cathode K of the conventional PALC, the space charge is unevenly distributed toward the cathode K, and thus the decay time of the space charge becomes long. On the other hand, in the PALC according to the present invention, the discharge is performed by applying voltages having the same magnitude to the cathode K and the anode A and having opposite phases (for example, 200V and -200V). . At this time, since the space charge is distributed relatively evenly on the cathode K and the anode A, the decay time of the space charge is reduced. In addition, since the anode A is divided into the _odd-numbered anode (a _odd ) and the _{even-numbered} anode (a _even ), a pulse having a positive voltage level is alternately applied. Accordingly, two pulses must be applied to the cathode K so that one pulse is applied to the _odd and _even anodes, respectively. That is, the pulse application period of the _odd-numbered anode (a _odd ) and the _{even-numbered} anode (a _even ) is reduced to 1/2 compared to the pulse application period of the cathode. Accordingly, the amount of space charge accumulated in the cell is reduced, thereby reducing the decay time.

As described above, the PALC according to the present invention alternates after forming the odd number anode in which the anode corresponding to the odd number of the total anodes are commonly connected, and the even number anode in which the anode corresponding to the even number is commonly connected, respectively. As a result, the driving voltage is applied to lower the driving voltage level. In addition, the PALC driving method according to the present invention enables low voltage driving by applying driving voltages having opposite phases to the cathode and the anode, and also enables high-speed driving by reducing the decay time.

As described above, the plasma address liquid crystal display and the driving method thereof according to the present invention have the advantage that the driving voltage can be reduced and the high speed driving can be achieved by applying the driving voltages of opposite phases to the anode and the cathode.

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)

In the driving method of a plasma address liquid crystal display device which generates a plasma discharge by applying a voltage to an anode and a cathode installed inside a discharge cell separated by partition walls formed at regular intervals between upper and lower substrates, A driving method of a plasma address liquid crystal display, characterized by applying a driving voltage having opposite phases to a cathode and an anode. The method of claim 1, And a driving voltage is alternately applied to the odd-numbered and even-numbered anodes of the anodes every cycle. The odd number anode, which commonly connects the odd number line of the anode line, And an even-numbered anode in which common anode lines corresponding to even-numbered ones of the anode lines are commonly connected.