KR100649529B1 - Plasma display and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to increase the low gray scale expression performance by reducing the light due to sustain discharge by floating X electrodes for the rest time of a second period in a sustain period. During a sustain period of a first subfield having the lowest weighted value, a driving method for driving one frame according to plural subfields in a plasma display device having plural first electrodes(Y) and plural second electrodes performing displaying together with the first electrodes comprises the steps of: increasing the voltage of the first electrodes from a second voltage(Vs) to a third voltage(Vset) while applying a first voltage to the first electrodes during a first period; applying the third voltage to the second electrodes during a second period; and applying a fourth voltage higher than the first voltage to the first electrodes during a predetermined period of the second period.

Description

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

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

2 and 3 are diagrams illustrating driving waveforms of the plasma display device according to the exemplary embodiment of the present invention, respectively.

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

The plasma display device is a display device using a plasma display panel that displays text or an image by using plasma generated by gas discharge. In the plasma display panel, dozens to millions or more of discharge cells are arranged in a matrix form according to their size.

In the plasma display device, one field (1TV field) is divided into a plurality of subfields having respective weights and driven, and the gray level is displayed by a combination of the weights of the subfields in which the display operation occurs among the plurality of subfields. In the address period of each subfield, the discharge cells to emit light and the discharge cells not to emit light by the address discharge are selected, and the discharge cells to emit light selected in the sustain period are sustained and discharged for a period corresponding to the weight of the subfield so that the image is displayed. Is displayed.

In such a plasma display device, low unit light should be implemented in a subfield representing a minimum gray scale (eg, 1 gray scale), which is advantageous for low gray scale representation. Here, the unit light refers to light in which the light due to the address discharge and the light due to the sustain discharge are added together in a subfield representing the minimum gray scale. Therefore, in general, in order to reduce the size of the unit light, a minimum sustain discharge, for example, one sustain discharge pulse (Vs voltage) is applied to the scan electrode so that only one sustain discharge occurs. However, even when the address discharge and the one sustain discharge in the address period are too strong, there is a problem in low gradation expression.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a driving method thereof capable of improving low gray scale expression.

According to an aspect of the present invention, in a plasma display device including a plurality of first electrodes and a plurality of second electrodes performing a display operation together with the plurality of first electrodes, one frame is driven by being divided into a plurality of subfields. A method is provided. The driving method includes the plurality of first electrodes in a state in which a first voltage is applied to the plurality of first electrodes during a first period in a sustain period of a first subfield having the lowest weight among the plurality of subfields. Increasing a voltage from a second voltage to a third voltage, applying the third voltage to the plurality of second electrodes during a second period, and the plurality of first electrodes during a portion of the second period And applying a fourth voltage higher than the first voltage to the.

According to another feature of the present invention, a plasma display device including a plasma display panel and a driver is provided. The plasma display panel includes a plurality of scan electrodes and a plurality of sustain electrodes which perform a display operation together with the plurality of scan electrodes. The driving unit applies a sustain discharge pulse having a first voltage and a second voltage higher than the first voltage to the plurality of scan electrodes in the sustain period of the first subfield having the lowest weight among the plurality of subfields. A third voltage between the first voltage and the second voltage is applied to the plurality of sustain electrodes for a part of a period during which the sustain discharge pulse is applied to the plurality of scan electrodes.

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 in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification. 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.

In addition, the wall charge in the present invention refers to a charge formed close to each electrode on the wall (eg, the dielectric layer) of the cell. 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. In addition, the wall voltage refers to the potential difference formed in the wall of the cell by the wall charge.

First, a plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1.

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. It includes.

The plasma display panel 100 includes a plurality of address electrodes (hereinafter referred to as “A electrodes”) A1 to Am extending in the column direction, and a plurality of sustain electrodes extending in pairs to each other in the row direction (hereinafter, “X”). Electrodes ”(X1 to Xn) and scan electrodes (hereinafter referred to as“ Y electrodes ”) (Y1 to Yn). In general, the X electrodes X1 to Xn are formed corresponding to the respective Y electrodes Y1 to Yn, and the display for displaying images in the sustain period between the X electrodes X1 to Xn and the Y electrodes Y1 to Yn. Perform the action. The Y electrodes Y1 to Yn and the X electrodes X1 to Xn are arranged to be orthogonal to the A electrodes A1 to Am. At this time, the discharge space at the intersection of the A electrodes A1 to Am and the X and Y electrodes X1 to Xn and Y1 to Yn forms the cell 12. 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 A electrode driving control signal, an X electrode driving control signal, and a Y electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields, and each subfield is composed of a reset period, an address period, and a sustain period.

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

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

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

Next, a driving waveform of the plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 2. In the following description, only the driving waveforms applied to the Y electrode, the X electrode, and the A electrode forming one cell will be described.

2 illustrates a driving waveform of a plasma display device according to an exemplary embodiment of the present invention. In FIG. 2, only the first and second subfields of the plurality of subfields are illustrated, and it is assumed that the first subfield is a subfield having a minimum weight among the plurality of subfields. In this case, the reset period of the first subfield consists of a rising period and a falling period, and the reset period of the second subfield consists of only a falling period.

As shown in Fig. 2, in the rising period of the reset period, the voltage of the Y electrode gradually increases from the voltage Vs to the voltage Vset while the X electrode is held at the reference voltage (0 V in Fig. 2). In FIG. 2, the voltage of the Y electrode is shown to increase in the form of a lamp. Then, while the voltage of the Y electrode is increased, a weak discharge (hereinafter referred to as “weak discharge”) occurs between the Y electrode and the X electrode and between the Y electrode and the A electrode, and a negative wall charge is applied to the Y electrode. And a positive wall charge is formed on the X and A electrodes.

In the falling period of the reset period, the voltage of the Y electrode gradually decreases from the Vs voltage to the Vnf voltage while the Ve voltage is applied to the X electrode. Then, while the voltage of the Y electrode decreases, a weak discharge occurs between the Y electrode and the X electrode, and between the Y electrode and the A electrode, and the negative wall charges formed on the Y electrode and the positive wall charges formed on the X electrode and the A electrode. Is erased to initialize the discharge cells. In general, the magnitude of the (Vnf-Ve) voltage is set near the discharge start voltage between the Y electrode and the X electrode. As a result, the wall voltage between the Y electrode and the X electrode becomes almost 0 V, whereby a cell that does not have an address discharge in the address period can be prevented from being erroneously discharged in the sustain period.

In order to select a discharge cell to be turned on in the address period, a scan pulse having a VscL voltage is sequentially applied to the plurality of Y electrodes while a Ve voltage is applied to the X electrode. At this time, the Va voltage is applied to the A electrode passing through the discharge cell to be selected from the plurality of discharge cells formed by the Y electrode and the X electrode to which the VscL voltage is applied. Then, an address discharge occurs between the A electrode to which the Va voltage is applied and the Y electrode to which the VscL voltage is applied, and the Y electrode to which the VscL voltage is applied, and the X electrode to which the Ve voltage is applied, thereby causing a positive wall charge, A, to the Y electrode. Negative wall charges are formed on the electrode and the X electrode, respectively. Here, the VscL voltage may be set at a level equal to or lower than the Vnf voltage. The VscH voltage higher than the VscL voltage is applied to the Y electrode to which the VscL voltage is not applied, and the reference voltage is applied to the A electrode of the discharge cell that is not selected.

Meanwhile, in order to perform this operation in the address period, the scan electrode driver 400 selects the Y electrode to which the scan pulse of the VscL voltage is to be applied among the Y electrodes Y1 to Yn. For example, in the single drive, the Y electrodes can be selected in the order arranged in the vertical direction. When one Y electrode is selected, the address electrode driver 300 selects a discharge cell to be turned on among discharge cells formed by the corresponding Y electrode. That is, the address electrode driver 300 selects a cell to which an address pulse of Va voltage is applied among the A electrodes A1 to Am.

Specifically, first, a scan pulse is applied to the Y electrode of the first row (Y1 in FIG. 1) and an address pulse is applied to the A electrode located in the cell to be turned on in the first row. Then, a discharge occurs between the Y electrode of the first row and the A electrode to which the address pulse is applied, thereby forming positive wall charges on the Y electrode and negative wall charges on the A and X electrodes, respectively. As a result, the wall voltage Vwxy is formed between the Y electrode and the X electrode so that the potential of the Y electrode is high with respect to the potential of the X electrode. Subsequently, while a scan pulse is applied to the Y electrode (Y2 of FIG. 1) in the second row, an address pulse is applied to the A electrode located in the cell to be turned on in the second row. Then, an address discharge occurs in the cell formed by the A electrode to which the address pulse is applied and the Y electrode in the second row, thereby forming wall charges in the cell. Similarly, an address pulse is applied to the A electrode positioned in the cell to be turned on while the scan pulse is sequentially applied to the Y electrodes of the remaining rows, thereby forming wall charges in the corresponding cell.

In the sustain period, a sustain discharge pulse having a high level voltage (Vs voltage in FIG. 2) and a low level voltage (0 V in FIG. 2) is applied to the Y electrode once. The voltage Vs / 2 is applied to the X electrode in a part of the period during which the sustain discharge pulse is applied to the Y electrode once. Specifically, in the first period in which the voltage of the Y electrode is increased from the 0V voltage to the Vs voltage, the 0V voltage is applied to the X electrode. The voltage Vs / 2 is applied to the X electrode during a part of the second period during which the voltage Vs is applied to the Y electrode, and the voltage 0 V is applied to the X electrode during the remaining part of the second period during which the Vs voltage is applied to the Y electrode. .

In general, since the wall voltage is formed between the Y electrode and the X electrode in the cell selected in the address period, the voltage of the Y electrode is increased to the Vs voltage while 0 V voltage is applied to the X electrode in the first period of the sustain period. Thereafter, a discharge occurs between the Y electrode and the X electrode when the Vs / 2 voltage is applied to the X electrode and the Vs voltage is applied to the Y electrode in some period of the second period. At this time, in some periods of the second period, the voltage difference (Vs-Vs / 2) between the X electrode and the Y electrode decreases as compared with the case where the Vs voltage is applied to the Y electrode and the 0 V voltage is applied to the X electrode. Occurs weakly As a result, some of the negative wall charges and positive wall charges formed on the X and Y electrodes, respectively, are erased. Subsequently, when 0 V voltage is applied to the X electrode in the remaining partial period of the second period, sustain discharge occurs between the Y electrode and the X electrode. However, since part of the wall charges formed on the X electrode and the Y electrode is partially erased in a part of the second period, sustain discharge occurs weakly between the X electrode and the Y electrode in the remaining part of the second period.

As such, in the first embodiment of the present invention, two weak sustain discharges occur in the sustain period. However, the amount of light due to the two sustain discharges is less than the amount of light caused by one strong sustain discharge between the Y electrode and the X electrode due to the Vs voltage being applied to the Y electrode and the 0 V voltage being applied to the X electrode. Reduced unit light improves low gradation expression.

Subsequently, in the falling period of the reset period of the second subfield, while the Ve voltage is applied to the X electrode, the voltage of the Y electrode gradually decreases from the Vs voltage to the Vnf voltage. At this time, when sustain discharge has occurred in the sustain period of the first subfield, since the negative wall charge is formed on the Y electrode and the positive wall charge is formed on the X electrode and the A electrode, the reset period of the first subfield is performed. As with the falling period of, the weak discharge occurs between the Y electrode and the X electrode and between the Y electrode and the A electrode while the voltage of the Y electrode is gradually decreased to the negative (-) wall charge and the X electrode and the A electrode formed on the Y electrode. The positive wall charges formed are erased to initialize the discharge cells. At this time, since the final voltage Vnf of the Y electrode in the reset period of the second subfield is the same as the final voltage Vnf of the Y electrode in the reset period of the first subfield, the cell after the end of the reset period of the second subfield The wall charge state becomes substantially the same as the wall charge state after the end of the reset period of the first subfield. The cell in which the address discharge has not occurred in the address period of the first subfield maintains the wall charge state after the end of the reset period of the first subfield. Since the wall voltage formed in the cell after the end of the reset period of the first subfield is formed near the discharge start voltage along with the applied voltage, no discharge occurs when the voltage of the Y electrode decreases to the Vnf voltage. Therefore, since such discharge does not occur in the reset period of the second subfield, the cell maintains the wall charge state set in the reset period of the first subfield. In this way, in the subfield in which the reset period is only in the falling period, reset discharge occurs when sustain discharge occurs in the immediately preceding subfield, and reset discharge does not occur when there is no sustain discharge.

Subsequently, the address period and the sustain period of the second subfield are the same as the first subfield. However, in the sustain period of the second subfield, the sustain discharge pulse is applied to the Y electrode and the X electrode in the opposite phase by the number of times corresponding to the weight indicated by the corresponding subfield.

In the first embodiment of the present invention, although the voltage of 0 V is applied to the X electrode during the remaining partial period of the second period in the sustain period, as in the second embodiment of the present invention shown in FIG. It is also possible to float the X electrode for a period of time. When the X electrode is floated, the supply of charge to the X electrode is stopped, so that the voltage of the X electrode is maintained at almost Vs / 2, so that the sustain discharge between the X electrode and the Y electrode is not maintained and disappears. Therefore, compared with the first embodiment, light due to sustain discharge can be further reduced.

2 and 3, the reset period of the first subfield is composed of the rising period and the falling period, but the reset period of the first subfield may be formed only of the falling period as in the second subfield.

Although the 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.

As described above, according to the present invention, the low gradation expression power is improved by reducing the amount of light due to sustain discharge in the sustain period of the subfield having the minimum weight.

Claims (8)

In a plasma display device including a plurality of first electrodes and a plurality of second electrodes performing a display operation together with the plurality of first electrodes, a method of driving one frame divided into a plurality of subfields is provided. In the sustain period of the first subfield having the lowest weight among the plurality of subfields, Increasing a voltage of the plurality of first electrodes from a second voltage to a third voltage while applying a first voltage to the plurality of first electrodes during a first period; Applying the third voltage to the plurality of second electrodes during a second period, and And applying a fourth voltage higher than the first voltage to the plurality of first electrodes during a portion of the second period. The method of claim 1, And floating the plurality of first electrodes during the remaining partial period of the second period. The method of claim 1, And applying the first voltage to the plurality of first electrodes during the remaining partial period of the second period. The method according to any one of claims 1 to 3, And the fourth voltage is an intermediate voltage between the second voltage and the third voltage. The method of claim 4, wherein In the sustain period of the first subfield and the reset period of the subfield, And gradually decreasing voltages of the plurality of second electrodes while the third voltage is applied to the plurality of second electrodes. A plasma display panel including a plurality of scan electrodes and a plurality of sustain electrodes performing a display operation together with the plurality of scan electrodes, and In the sustain period of the first subfield having the lowest weight among the plurality of subfields, a sustain discharge pulse having a first voltage and a second voltage higher than the first voltage is applied to the plurality of scan electrodes, And a driver configured to apply a third voltage between the first voltage and the second voltage to the plurality of sustain electrodes during a part of a period during which the sustain discharge pulse is applied to a scan electrode. The method of claim 6, The driving unit, And plasma the plurality of sustain electrodes for the remaining portion of the period during which the sustain discharge pulse is applied to the plurality of scan electrodes. The method of claim 6, The driving unit, And applying the first voltage to the plurality of sustain electrodes during the remaining part of the period during which the sustain discharge pulse is applied to the plurality of scan electrodes.

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