KR100648708B1 - Plasma display and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to increase low gray scale expression performance by reducing unit light in a subfield having the minimum weighted value. In a plasma display device having plural first electrodes(Y), plural second electrodes(X) performing displaying together with the first electrodes, and plural third electrodes(A) formed across the first and second electrodes, and plural discharge cells defined by the first, second, and third electrodes, a driving method for driving one frame according to plural subfields includes the steps of: detecting a screen load factor from an image signal input during the period of one frame; gradually increasing the voltage of the first electrodes from a first voltage(Vs) to a second voltage(Vset) during a sustain period of a first subfield having the lowest weighted value; and selectively applying a third voltage higher than the first voltage to the second electrodes on the basis of the detected screen load factor after the voltage of the first electrode is increased up to the second voltage during the sustain period of the first subfield.

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 first and second exemplary embodiments 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 frame (1TV field) is divided into a plurality of subfields having respective weights and driven, and gray scales are displayed by a combination of weights of subfields in which a display operation occurs among the plurality of subfields. In the address period of each subfield, discharge cells to emit light and discharge cells not to emit light are selected by the address discharge, 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 to display an image. do.

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, a plurality of first electrodes and a plurality of second electrodes performing a display operation together with the plurality of first electrodes are formed in a direction crossing the plurality of first electrodes and the plurality of second electrodes. A method of driving a frame by dividing one frame into a plurality of subfields is provided in a plasma display device including a plurality of third electrodes and a plurality of discharge cells respectively defined by the first and second electrodes. do. The driving method may include detecting a load factor from an image signal input for one frame, and performing a first period in a sustain period of a first subfield having the lowest weight among the plurality of subfields. Gradually increasing a voltage from a first voltage to a second voltage, and after the first period in the sustain period of the first subfield according to the detected load rate, the plurality of second electrodes than the first voltage. Selectively applying a high third voltage.

According to another feature of the present invention, a plasma display device including a plasma display panel, a driver, and a controller is provided. The plasma display panel includes a plurality of first electrodes, a plurality of second electrodes, a plurality of third electrodes formed in a direction crossing the first electrode and the second electrode, the first electrodes, the second electrodes, and the It includes a plurality of discharge cells respectively defined by each third electrode. In the address period of the subfield having the lowest weight among the plurality of subfields, the driver may apply the voltages of the plurality of first electrodes to the first electrode while applying a first voltage to the plurality of second electrodes during the first period. Incrementally increases from voltage to the second voltage. The control unit detects a screen load ratio of an image signal input for one frame and in response to the first voltage being applied to the plurality of first electrodes after the first period according to the detected screen load ratio, the plurality of second electrodes. The driving of the driving unit is controlled to selectively apply a third voltage higher than the first voltage to the.

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 an image 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 and 3 are diagrams illustrating driving waveforms of the plasma display device according to the first and second exemplary embodiments of the present invention, respectively. 2 and 3 illustrate only subfields having a minimum weight among a plurality of subfields.

First, 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 the discharge cells to be turned on in the address period, while the Ve voltage is applied to the X electrode, the scan pulse intensity ls having the VscL voltage is sequentially applied to the plurality of Y electrodes. At this time, an address pulse having a 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.

On the other hand, in order to perform this operation in the address period, the scan electrode driver 400 selects the Y electrode to which the scan pulse 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 of 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, the voltage of the Y electrode is gradually increased from the 0V voltage to the Vs voltage while the reference voltage is applied to the X electrode and the A electrode, respectively, and then the Vs voltage is applied. In FIG. 2, the voltage of the Y electrode is shown to increase in the form of a lamp. Then, a weak sustain discharge occurs between the Y electrode and the X electrode while the voltage of the Y electrode is increased. Therefore, the amount of light due to sustain discharge is reduced as compared with the case where the voltage Vs is applied to the Y electrode as in the prior art. As a result, the size of the unit light is reduced, thereby improving low gray level expressive power.

Meanwhile, in the plasma display device, the controller 200 calculates an automatic power control (APC) level according to a load ratio detected for image data input from the outside, and calculates the number of sustain discharge pulses corresponding to the calculated APC level. Therefore, the total number of sustain discharge pulses allocated to one frame varies according to the screen load ratio of the plasma display panel 100. That is, since the power consumption increases when the screen load ratio of the plasma display panel 100 is large, the number of sustain discharge pulses allocated to one frame is reduced, and when the screen load ratio is small, the number of sustain discharge pulses allocated to one frame is increased.

For example, assuming that one sustain discharge pulse is allocated to a subfield representing one gray level when the screen load ratio of the plasma display panel 100 is greater than a threshold in the plasma display device, the size of unit light is as shown in FIG. 2. Can be reduced. However, when the screen load ratio of the plasma display panel 100 is smaller than the threshold value, the unit light is larger than the case where the screen load ratio of the plasma display panel 100 is larger than the threshold value to ensure subsequent subfields and gradation linearity. As described above, when the screen load ratio of the plasma display panel 100 is smaller than the threshold value, as in the second embodiment of the present invention illustrated in FIG. 3, the Y electrode after the voltage of the Y electrode is increased to the Vs voltage in the sustain period. And a sustain discharge pulse having a high level voltage (Vs voltage in FIG. 3) and a low level voltage (0 V in FIG. 3) is applied to the X electrode while a reference voltage is applied to the A electrode. Then, sustain discharge occurs between the Y electrode and the X electrode. At this time, since the sustain discharge is weak and the wall charge is less formed in each electrode, the weak sustain discharge occurs between the Y electrode and the X electrode. As a result, one weak sustain discharge is generated between the Y electrode and the X electrode as compared with the first embodiment, so that the unit light is larger than that of the first embodiment.

On the other hand, in Figures 2 and 3, although the reset period is made up of the rising period and the falling period, the reset period may be made of only the falling period.

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, it is possible to reduce the unit light in the subfield having the minimum weight, thereby improving the low gradation power. In particular, low gray scale linearity can be secured by adjusting the unit light in the subfield having the minimum weight in accordance with the screen load ratio of the rasma display panel.

Claims (5)

A plurality of second electrodes performing a display operation together with the plurality of first electrodes and the plurality of first electrodes, a plurality of third electrodes formed in a direction crossing the plurality of first electrodes and the plurality of second electrodes, and In a plasma display device including a plurality of discharge cells defined by the plurality of first electrodes, the plurality of second electrodes, and the third electrode, the method of driving one frame divided into a plurality of subfields, Detecting a screen load ratio from an image signal input for one frame; Gradually increasing voltages of the plurality of first electrodes from a first voltage to a second voltage in the sustain period of the first subfield having the lowest weight among the plurality of subfields, and A third higher than the first voltage on the plurality of second electrodes after the voltages of the plurality of first electrodes are increased to the second voltage in the sustain period of the first subfield based on the detected screen load ratio A method of driving a plasma display device comprising the step of selectively applying a voltage. The method of claim 1, And not applying the third voltage when the detected screen load ratio is greater than a threshold load ratio, and applying the third voltage when the detected screen load ratio is less than the threshold load ratio. The method according to claim 1 or 2, In the address period of the first subfield, Sequentially applying scan pulses to the plurality of first electrodes, and And applying an address pulse to a third electrode of a cell to be turned on among discharge cells formed by the plurality of first electrodes to which the scan pulse is applied. A plasma display panel including a plurality of first electrodes and a plurality of second electrodes, and a plurality of discharge cells defined by the plurality of first electrodes and the plurality of second electrodes, respectively; In the sustain period of the subfield having the lowest weight among the plurality of subfields, the voltages of the plurality of first electrodes are gradually increased from the second voltage to the third voltage while the first voltage is applied to the plurality of second electrodes. Driving unit to increase, and After increasing the voltages of the plurality of first electrodes to the third voltage, the first voltage is applied to the plurality of first electrodes based on the screen load ratio detected from the image signal input for one frame. And a controller configured to control the driving unit to selectively apply a fourth voltage higher than the first voltage to a plurality of second electrodes. The method of claim 4, wherein The control unit, In the sustain period of the subfield having the lowest weight in the frame in which the detected screen load ratio is greater than the threshold load ratio, the detected screen load ratio is greater than the threshold load ratio without applying the fourth voltage to the plurality of second electrodes. And a third voltage applied to a plurality of second electrodes in the sustain period of the subfield having the lowest weight in a small frame.

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