KR100759397B1 - Plasma display device and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to control wall charge in a reset period to be suitable for an address operation by reducing the amount of wall charge formed outside each electrode. A driving method of a plasma display device includes the steps of: applying first and second voltages to first and second electrodes in a first period of a sustain period of a first sub field; applying third and fourth voltages to the first and second electrodes in a second period subsequent to the first period; raising the voltage of the first electrode to seventh voltage from sixth voltage; and raising the voltage of the first electrode to ninth voltage from tenth voltage. The difference between the third and fourth voltages is less than the difference between the first and second voltages.

Description

Plasma display device and driving method thereof {PLASMA DISPLAY DEVICE AND DRIVING METHOD THEREOF}

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

2 illustrates a driving waveform of the plasma display device according to the first embodiment of the present invention.

3A to 3C are diagrams showing the state of wall charges formed in each electrode when the waveform shown in FIG. 2 is applied.

4 illustrates a driving waveform of the plasma display device according to the second embodiment of the present invention.

5 illustrates a driving waveform of a plasma display device according to a third exemplary embodiment of the present invention.

The present invention relates to a plasma display device and a driving method thereof.

A plasma display device is a flat display device that displays characters or images by using plasma generated by gas discharge, and the display panel includes dozens or millions of discharge cells (hereinafter referred to as "cells") depending on the size thereof. This matrix is arranged.

The plasma display device divides one frame into a plurality of subfields having respective weights, and time-division controls them to implement gray scale. Each subfield consists of a reset period, an address period, and a sustain period. In this case, the reset period is a period for initializing the state of each cell in order to perform an address operation smoothly on the cell, and the address period is a period for selecting a cell to be turned on from a plurality of cells through address discharge. In addition, the sustain period is a period for sustain discharge of the cell to be turned on.

In general, a high voltage is applied when performing initialization for all cells in the reset period. Even when a zero gray scale screen is expressed by such a high voltage, reset discharge occurs in all cells, and the screen looks cloudy. In order to prevent such a phenomenon, there is a method of changing a waveform applied in the reset period of the first subfield and the reset period of the remaining subfield after dividing one frame into a plurality of subfields.

According to the above driving method, in the reset period of the first subfield, all the discharge cells are applied by applying a rising ramp pulse for gradually increasing the voltage of the scan electrode and then applying a falling ramp pulse for gradually decreasing the voltage of the scan electrode. Initialize In the reset period of the remaining subfields, only a falling ramp pulse for gradually decreasing the voltage of the scan electrode is applied to initialize only the cells in which the sustain discharge has occurred in the previous subfield. At this time, when a sustain voltage is applied to the scan electrode when the last sustain discharge pulse is applied in the sustain period of the first subfield, a negative discharge is formed in the scan electrode and a positive wall charge is formed in the sustain electrode. do. As a result, the wall voltage formed between the scan electrode and the sustain electrode ends in a high state. However, since only the falling ramp pulse is applied to the scan electrodes in the reset period of the subfield after the first subfield, the wall charges formed in each electrode in the sustain period of the previous subfield are not controlled to be suitable for the address operation. That is, when strong discharge occurs in the sustain period of the first subfield, wall charges are applied to the outer region of each electrode (the portion corresponding to the outer region in the portion forming the discharge cell between the electrodes, which is the same below). The wall charge is not properly controlled by the falling ramp pulse applied in the reset period of the second subfield because it is accumulated a lot. At this time, in the case of a cell in which the wall charge is less than the desired state between the scan electrode and the address electrode, the address discharge occurs weakly, and a low discharge phenomenon may occur in the sustain period. In the case where more wall charges are formed between the scan electrode and the address electrode than the desired state, address discharge may occur in a cell that will not be selected in the address period, and thus an erroneous discharge phenomenon may occur in the sustain period. This phenomenon also tends to occur better in high temperature environments.

SUMMARY OF THE INVENTION The present invention provides a plasma display device which prevents mis-discharge and low discharge occurring in an address period and a sustain period of a subsequent subfield when a strong discharge occurs during sustain discharge in a sustain period of a previous subfield; To provide a driving method.

According to an aspect of the present invention for achieving the above object, there is provided a method of driving a plasma display device including a plurality of first electrodes and a second electrode for performing a display operation with the plurality of first electrodes. The driving method includes applying a first voltage and a second voltage to the first electrode and the second electrode, respectively, in a first period of a sustain period of a first subfield, and a second period subsequent to the first period. In the step of applying a third voltage and a fourth voltage to the first electrode and the second electrode, respectively, and in a third period continuous to the second period, the state of maintaining the voltage of the second electrode at a fifth voltage Gradually increasing the voltage of the first electrode from the sixth voltage to the seventh voltage. At this time, the voltage difference between the third voltage and the fourth voltage is smaller than the voltage difference between the first voltage and the second voltage and the third voltage is negative polarity.

According to another feature of the present invention, a plasma display device is provided. The plasma display device includes a plasma display panel including a plurality of first electrodes and a second electrode, the plurality of discharge cells being formed by the plurality of first electrodes and the second electrodes, a driving unit for driving the plasma display panel; And a control unit for dividing one frame into a plurality of subfields each including a reset period, an address period, and a sustain period, to control the driving unit. In this case, the driving unit applies the first sustain discharge pulse having the first voltage to the first electrode in the first period of the sustain period of the first subfield, and the first period in the second period continuous to the first period. A second sustain discharge pulse having a second voltage is applied to the electrode, and the voltage of the first electrode is gradually raised in the third period subsequent to the second period. In this case, the absolute value of the second voltage is smaller than the absolute value of the first voltage, and the second sustain discharge pulse applied to the first electrode has a negative polarity.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

In the present invention, the wall charge refers to a charge formed close to each electrode on the wall of the cell (eg, the dielectric layer). And the wall charge is not actually in contact with the electrode itself but is described here as "formed", "accumulated" or "stacked" on the electrode, where the wall voltage refers to the potential difference formed on the wall of the cell by the wall charge. In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

A plasma display device and a driving method thereof according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention. As shown in FIG. 1, a plasma display device according to an exemplary embodiment of the present invention includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500. ).

The plasma display panel 100 includes a plurality of address electrodes A1-Am extending in the column direction, a plurality of sustain electrodes X1-Xn extending in the row direction, and a plurality of scan electrodes Y1-Yn. The plurality of scan electrodes Y1-Yn and the sustain electrodes X1-Xn are arranged in pairs with each other. The discharge cells are formed by the adjacent scan electrodes, the sustain electrodes, and the address electrodes crossing them. The structure of the plasma display panel 100 is an example, and a panel having another structure to which the driving waveform described below may be applied may also be applied to the present invention.

The controller 200 receives an image signal from the outside and outputs an address electrode driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields. At this time, each subfield is composed of a reset period, an address period, and a sustain period when expressed as a temporal operation change.

The address electrode driver 300 receives an address electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode.

The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrode.

The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrode.

FIG. 2 is a diagram illustrating driving waveforms of a plasma display device according to a first exemplary embodiment of the present invention, and FIGS. 3A to 3C are diagrams showing states of wall charges formed at respective electrodes when the waveforms shown in FIG. 2 are applied. to be. 2 illustrates a driving waveform applied to the sustain period of the first subfield, which is an arbitrary subfield, and a driving waveform applied to the reset period and the address period of the second subfield subsequent to the first subfield. Omitted.

In the sustain period of the first subfield, a sustain discharge pulse voltage (Vs voltage) is alternately applied to the scan electrode Y and the sustain electrode X to select a cell selected in an address period (not shown) of the first subfield. Keep discharge. At this time, when the sustain discharge pulse voltage Vs is applied to the sustain electrode X in the period S2 before the last sustain discharge pulse is applied, sustain discharge occurs in the selected cell, as shown in FIG. 3A. Wall charges are formed on each electrode. That is, the sustain discharge pulse voltage Vs is applied to the sustain electrode X, and a reference voltage (0 V in FIG. 2) is applied to the address electrode A and the scan electrode Y. Then, strong discharge occurs between the scan electrode Y and the sustain electrode X and between the address electrode A and the sustain electrode X so that a large amount of negative wall charges are widened on the sustain electrode X. And a large amount of positive wall charges are formed widely on the scan electrode Y and the address electrode A. FIG.

Next, in the period S1 during which the last sustain discharge pulse is applied, the voltage of the scan electrode Y is gradually raised from the voltage Vsp to the voltage Vsr while the reference voltage is applied to the sustain electrode X. Then, a weak discharge is generated between the scan electrode Y and the sustain electrode X and between the scan electrode Y and the address electrode A, and wall charges are formed on each electrode as shown in FIG. 3B. In general, weak discharges having a weak discharge intensity have less wall charges in the outer region of each electrode in the period S1 during which the last sustain discharge pulse is applied since the discharges do not diffuse to the entire region of the electrode. At this time, the Vsp voltage is appropriately set to a voltage such that no strong discharge occurs due to the voltage difference between the wall voltage and the Vsp voltage formed in the previous sustain discharge. The Vsr voltage is appropriately set to a voltage for sustaining and discharging only selected cells in the address period (not shown) of the first subfield. On the other hand, the Vsr voltage may be set to the same voltage as the Vs voltage to reduce the number of voltage sources generating the Vsr voltage.

Subsequently, in the reset period of the second subfield, the voltage of the scan electrode Y is gradually decreased from the voltage Vsf to the voltage Vnf while the voltage Ve is applied to the sustain electrode X. FIG. Then, a weak reset discharge occurs only in the cells selected and sustained in the address period of the first subfield, and no discharge occurs in the cells not selected. At this time, the wall charge state of the cell sustained and discharged in the first subfield is a state in which almost no wall charge is formed in the outer region of the electrode, as shown in FIG. 3B. Therefore, even if only a waveform for gradually decreasing the voltage of the scan electrode Y is applied in the reset period of the second subfield, as shown in FIG. 3C, the wall charge can be controlled, so that the wall charge state of each electrode is suitable for the address operation. It becomes a state. At this time, the Vsf voltage may be set to the same voltage as the Vsp voltage to reduce the voltage source. In addition, although the voltage waveform gradually rising or falling in the sustain period or the reset period is shown as a ramp waveform in FIG. 2, other waveforms that gradually rise or fall may be applied, such as an RC resonance waveform, a log waveform, and a step waveform.

Next, in order to select a cell to emit light in the address period of the second subfield, a scan pulse having a Vscl voltage is sequentially applied to the scan electrode Y, and the scan electrode Y to which the Vscl voltage is not applied is biased to the Vsch voltage. do. Then, an address pulse having a Va voltage is applied to the address electrode A of the cell to be selected from among the plurality of cells formed by the scan electrode Y to which the Vscl voltage is applied. The unselected address electrode A is biased to the reference voltage (0V). Then, an address discharge is generated in a cell formed by the address electrode A to which Va voltage is applied and the scan electrode Y to which Vscl voltage is applied, and a positive wall charge is formed on the scan electrode and the sustain electrode ( Wall charges are formed. As such, when the last sustain discharge generated in the sustain period of the previous subfield is generated by weak discharge rather than strong discharge, less wall charge is formed in the outer region of each electrode. Therefore, even if only a voltage waveform gradually descending to the scan electrode is applied in the subsequent reset period of the subfield, wall discharge suitable for the address operation is formed by the reset discharge.

In the above, a method of facilitating wall charge control in a subsequent reset period by reducing the amount of wall charges formed in the outer region of the electrode by generating the last sustain discharge as a weak discharge rather than a strong discharge has been described. In the following, in the case of weakly discharging the last sustain discharge and the sustain discharge just before the last sustain discharge, an embodiment in which the same effect can be further reduced by reducing the amount of wall charges formed in the outer region of each electrode is shown in FIGS. 4 and 5. It demonstrates with reference to. In addition, in FIG. 4 and FIG. 5, the driving waveforms and operations in other periods are similar to those of FIG. 2 except for the driving waveforms applied to cause the sustain discharge in the sustain period of the first subfield.

4 illustrates a driving waveform of the plasma display device according to the second embodiment of the present invention.

 In FIG. 4, unlike in FIG. 2, the sustain discharge pulse voltage is lower than the voltage Vs to the sustain electrode X to cause the sustain discharge in the period S2 of the period S1 during which the last sustain discharge pulse of the first subfield is applied. Apply the voltage Vs1. At this time, a reference voltage (0 V in FIG. 4) is applied to the address electrode A and the scan electrode Y. FIG. Then, the weak discharge occurs because the voltage difference between the scan electrode Y and the sustain electrode X is smaller than the voltage difference at the previous sustain discharge. Thus, less wall charge is formed in the outer region of each electrode. Here, the voltage Vs1 should be appropriately set so that the discharge between the scan electrode Y and the sustain electrode X is weakly discharged.

Then, in the period S1 during which the last sustain discharge pulse is applied, the voltage of the scan electrode Y is changed to Vsr at the voltage Vsp while the reference voltage 0V is applied to the sustain electrode X as in the first embodiment. Incrementally ramp up to voltage. Then, the weak discharge occurs once more between the scan electrode Y and the sustain electrode X, thereby further reducing the amount of wall charges formed in the outer region of each electrode. As a result, it is easier to control the wall charge through the reset discharge in the subsequent reset period of the second subfield, so that the wall charge state suitable for the address operation can be set.

5 is a diagram illustrating driving waveforms of a plasma display device according to a third exemplary embodiment of the present invention.

In FIG. 5, instead of applying the Vs voltage as the sustain discharge pulse voltage to the sustain electrode X in the period S2 of the period S1 in which the last sustain discharge pulse of the first subfield is applied, the reference voltage (FIG. 5). In this case, a voltage Vs2 having a negative polarity is applied to the scan electrode Y while 0 V) is applied. At this time, the Vs2 voltage is a voltage whose absolute value is smaller than the absolute value of the Vs voltage. In addition, the Vs2 voltage should be appropriately set so that weak discharge between scan electrode Y and sustain electrode X occurs. Then, the voltage difference between the scan electrode Y and the sustain electrode X is smaller than the voltage difference at the previous sustain discharge, so that weak discharge occurs and less wall charges are formed in the outer region of each electrode. In this case, in order to reduce the voltage source of the Vs2 voltage, the Vs2 voltage may be set to the same voltage as the scan pulse voltage Vscl of the scan electrode Y. Then, in the period S1 during which the last sustain discharge pulse of the first subfield is applied, the voltage of the scan electrode Y is changed from the voltage Vsp to the voltage Vsr while the reference voltage 0V is applied to the sustain electrode X. Incrementally raises. Then, weak discharge occurs once more from the scan electrode Y to the sustain electrode X, so that less wall charges are formed in the outer region between each electrode.

As such, if less wall charges are formed in the outer region of each electrode by causing a weak discharge in the sustain period of the previous subfield or immediately after the last sustain discharge pulse is applied, the scan electrodes in the reset period of the next subfield Even if only a gradually decreasing voltage is applied to (Y), wall charge control is possible to be suitable for the address operation. As a result, erroneous discharge and low discharge in the address period can be prevented.

Meanwhile, in the second and third embodiments of the present invention, a waveform for gradually increasing the voltage of the scan electrode Y is applied in the period S1 during which the last sustain discharge pulse of the first subfield is applied. The Vs1 voltage may be applied to the scan electrode Y to generate the weak discharge subsequent to the period S2 immediately before the last sustain discharge period of the first subfield.

Further, in the second and third embodiments of the present invention, instead of applying a voltage gradually rising to the scan electrode Y in the period S1 where the last sustain discharge pulse of the first subfield is applied, the scan electrode It is also possible to generate a weak discharge subsequent to the period S2 immediately before the last sustain discharge period of the first subfield by applying a positive polarity voltage having the same absolute value as the Vs2 voltage to (Y).

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an embodiment of the present invention, by generating a weak discharge in the sustain period of the previous subfield to reduce the amount of wall charges formed in the outer region of each electrode, the wall charges in the subsequent reset period are controlled to a state suitable for the address operation. can do. Through this, mis-discharge and low discharge can be prevented.

Claims (9)

A plurality of first electrodes and a plurality of second electrodes performing a display operation together with the plurality of first electrodes, and dividing one frame into a plurality of subfields including a reset period, an address period, and a sustain period, respectively. In the method of driving a plasma display device, Applying a first voltage and a second voltage to the first electrode and the second electrode in the first period of the sustain period of the first subfield; Applying a third voltage and a fourth voltage to the first electrode and the second electrode, respectively, in a second period subsequent to the first period; Gradually increasing the voltage of the first electrode from the sixth voltage to the seventh voltage while maintaining the voltage of the second electrode at a fifth voltage in a third period subsequent to the second period; And In the reset period of the second subfield subsequent to the first subfield, the voltage of the first electrode is gradually decreased from the ninth voltage to the tenth voltage while the voltage of the second electrode is maintained at the eighth voltage. Including the steps of The voltage difference between the third voltage and the fourth voltage is less than the voltage difference between the first voltage and the second voltage and the third voltage is negative polarity, And a reset discharge is generated only in a cell turned on in the address period of the first subfield in the reset period of the second subfield. delete The method of claim 1, And the fourth voltage is a ground voltage. The method of claim 1, And the third voltage is equal to the voltage of the scan pulse applied to the first electrode in the address period of the second subfield. A plasma display panel including a plurality of first electrodes and a second electrode, wherein a plurality of discharge cells are formed by the plurality of first and second electrodes; A driving unit driving the plasma display panel; And A control unit for controlling the driving unit by dividing one frame into a plurality of subfields each including a reset period, an address period, and a sustain period; The driving unit, In a first period of the sustain period of the first subfield, a first sustain discharge pulse having a first voltage is applied to the first electrode, Applying a second sustain discharge pulse having a second voltage having an absolute value smaller than an absolute value of the first voltage to the first electrode in a second period subsequent to the first period, In a third period continuous to the second period, the voltage of the first electrode is gradually raised, In the reset period of the second subfield subsequent to the first subfield, the voltage of the first electrode is gradually decreased. The second sustain discharge pulse applied to the first electrode has a negative polarity, And a reset discharge is generated only in the discharge cells selected in the address period of the first subfield in the reset period of the second subfield. delete The method of claim 5, The driving unit, And applying a ground voltage to the second electrode in the first to third periods. In claim 5, And the second voltage is equal to a voltage of a scan pulse applied to the first electrode in an address period of a second subfield subsequent to the first subfield. In claim 5, And the first sustain discharge pulse has a positive polarity.

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