KR100658628B1 - Plasma display device and driving method thereof - Google Patents

Abstract

The present invention relates to a plasma display device and a driving method thereof. According to the present invention, when the sustain discharge by the unit light occurs in the continuous low gradation subfields, the main reset waveform is applied in the reset period of the subsequent subfields to the subfield where the sustain discharge by the unit light has occurred. In this way, low discharge and false discharge occurring in subsequent subfields can be prevented.

Plasma display, unit light, low gradation

Description

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

1 is a schematic diagram of 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.

3 illustrates driving waveforms of a plasma display device according to a second exemplary embodiment of the present invention.

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

A plasma display panel is a flat display device that displays characters or images by using plasma generated by gas discharge, and tens to millions or more of pixels are arranged in a matrix form according to their size.

The plasma display device is driven by dividing one frame into a plurality of subfields having respective weights, and expressing gray scales by the combination of these subfields.

Each subfield consists of a reset period, an address period, and a sustain period.

The reset period is a period for initializing the state of each cell in order to smoothly perform an addressing operation on a discharge cell (hereinafter, referred to as a 'cell'), and the address period is turned on to distinguish between cells that are turned on and cells that are not turned on in a panel. Is a period during which the wall charges are accumulated in the cells (addressed cells). The sustain period is a period in which a discharge for actually displaying an image on the addressed cell is applied by applying a sustain discharge voltage pulse. At this time, the address period is given equally to all subfields.

Since the light intensity due to the reset discharge is weaker than the light intensity due to the address discharge or the sustain discharge, the light in the minimum weighted subfield is determined by the light implemented by the one sustain discharge pulse and the light by the address discharge. Generally called unit light.

However, when there is an address discharge or sustain discharge, the light due to the reset discharge can be ignored, but in the subfield without the address discharge, there is no other light, so the light due to the reset discharge is felt to be insignificant and the black screen appears whitish. Occurs. As a result, as described in US Pat. No. 6,289,875, a reset discharge is generated only for a cell (turned-on cell) in which the sustain discharge has occurred in the immediately preceding subfield, and a reset discharge is performed for a cell (not turned-on) in which the sustain discharge has occurred in the immediately preceding subfield. An auxiliary reset waveform that does not occur is used.

However, the auxiliary reset waveform is applied on the assumption that enough negative charges are accumulated on the Y electrode through sustain discharge. Since the wall charge is not formed on the Y electrode after the unit light discharge, the auxiliary reset waveform is applied in the subsequent subfield. This prevents complete reset discharge in the cell. Such incomplete reset discharge also affects subsequent address discharges and sustain discharges, resulting in low discharge.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a driving method thereof for preventing low discharge in a subfield representing low gray levels.

According to an aspect of the present invention, there is provided a method of driving a plasma display device, the plurality of first electrodes, the plurality of second electrodes, and the plurality of third electrodes formed in a direction crossing the first electrode and the second electrode. A method of driving a plasma display device comprising:

In the sustain period of the first subfield having the minimum weight, applying a sustain discharge pulse to the first electrode once, in the reset period of the at least one second subfield successively in time to the minimum weight subfield, Gradually decreasing the voltage difference between the first electrode and the second electrode and the voltage difference between the first electrode and the third electrode, respectively, during the sustain period of the second subfield, applying a sustain discharge pulse to the first electrode. The step of applying once, the voltage difference between the first electrode and the second electrode and the voltage difference between the first electrode and the third electrode in the reset period of the third subfield continuous in time to the second subfield Are gradually increased and then gradually decreased, and sustain discharge pulses are alternately applied to the first electrode and the second electrode in the sustain period of the third subfield, And applying a sustain discharge pulse a plurality of times.

According to an aspect of the present invention, there is provided a plasma display device including a plasma display panel including a plurality of discharge cells, a number of sustain discharge pulses according to a load ratio, and a frame divided into a plurality of subfields having respective weights for gray scale display. A control unit for determining the number of application of the sustain discharge pulse for each subfield, and a driving circuit for supplying a driving voltage to an electrode forming the discharge cell according to a control signal of the control unit;

The drive circuit,

In the reset period of the first subfield having the minimum weight, initializing the states of the discharge cells in which sustain discharge has occurred and the discharge cells in which sustain discharge has not occurred,

The state of the discharge cell in which sustain discharge has occurred in the immediately preceding subfield in the reset period of at least one second subfield consecutive in time in which the number of sustain discharge pulses applied to each subfield among the subfields except the first subfield is 1; To initialize

In the reset period of the third subfield located after the plurality of consecutive subfields, the states of the discharge cells in which sustain discharge has occurred in the immediately preceding subfield and the discharge cells in which sustain discharge has not occurred are initialized.

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 in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

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

1 is a schematic diagram of 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 driver 300, and a sustain electrode driver (hereinafter referred to as an “X electrode driver”) ( 400 and a scan electrode driver (hereinafter, referred to as a 'Y electrode driver') 500.

The plasma display panel 100 includes a plurality of address electrodes A1-Am arranged in a column direction, a plurality of sustain electrodes (hereinafter referred to as 'X electrodes') (X1-Xn) and scans arranged in a row direction. Electrodes (hereinafter referred to as 'Y electrodes') Y1-Yn. The X electrodes X1-Xn are formed corresponding to the respective Y electrodes Y1-Yn, and generally have one end connected in common to each other. The Y electrodes Y1-Yn and the address electrodes A1-Am and the X electrodes X1-Xn and the address electrodes A1-Am are arranged to be orthogonal to each other. At this time, the discharge space at the intersection of the address electrodes A1-Am and the X and Y electrodes X1-Xn and Y1-Yn forms a cell.

The controller 200 receives an image signal from the outside and outputs an address 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 driver 300 receives an address driving control signal from the controller 200 and applies a display data signal for selecting a cell to be displayed to each address electrode A1-Am. The X electrode driver 400 receives the X electrode driving control signal from the controller 200 to apply a driving voltage to the X electrodes X1 to Xn, and the Y electrode driver 500 controls the Y electrode driving from the controller 200. The signal is received and a driving voltage is applied to the Y electrodes Y1-Yn.

On the other hand, in general, the plasma display device has a high discharge voltage and thus high power consumption. Since the power consumption increases with the screen load ratio, the plasma display device uses a method of controlling power consumption according to the screen load ratio, which is called an auto power control (APC).

The APC adjusts the number of sustain discharge pulses allocated to one frame according to the screen load ratio. Therefore, when the screen load ratio is high, the number of sustain discharge pulses is small, so that one sustain discharge pulse is allocated to several low-weight subfields. It may become.

In this case, the controller 200 outputs a control signal to the X electrode driver 400 or the Y electrode driver 500 to cause one sustain discharge to occur in the X electrode or the Y electrode in the sustain period of each subfield.

On the other hand, in the first sustain discharge, a discharge occurs between the X electrode and the Y electrode, and a discharge occurs between the address electrode and the Y electrode, and from the second sustain discharge, only a discharge occurs between the X electrode and the Y electrode and the wall charge accumulated on the address electrode Converge to a certain level.

As described above, the auxiliary reset waveform is applied in the reset period of the subfield after the sustain discharge by the unit light.

However, in the case of sustain discharge using unit light, since the positive charges are excessively accumulated on the address electrode and the sufficient positive charges are not accumulated on the Y electrode as compared with the case where a continuous sustain discharge pulse is applied, the continuous subfield When the auxiliary reset waveform is applied for a while, the probability of low discharge occurring in the address period and the sustain period of the subsequent subfield is further increased.

Therefore, an embodiment of the present invention proposes a method for preventing low discharge in subsequent subfields when sustain discharge by unit light occurs during such continuous subfields.

Hereinafter, a driving method of the plasma display device according to the first embodiment of the present invention will be described with reference to FIGS. 2 and 3.

2 is a driving waveform diagram of a plasma display device according to a first exemplary embodiment of the present invention, in which discharge by unit light is continuously performed in the sustain periods of the first, second and third subfields SF1 to SF3. It shows the case where it happens.

As shown in FIG. 2, according to the first embodiment of the present invention, in the reset period of the subfield SF1, the main electrode gradually rises from the Vs voltage to the Vset voltage and slowly descends from the Vs voltage to the VscL voltage in the Y electrode. The reset waveform is applied. At this time, a reference voltage (0V) is applied to the address electrode, a reference voltage (0V) is applied to the X electrode when a rising ramp voltage is applied to the Y electrode, and a X-terminal is applied to the X electrode when a falling ramp voltage is applied to the Y electrode. Ve voltage is applied.

When the main reset waveform is applied as described above, weak discharge occurs from the Y electrode to the address electrode and the X electrode while the rising ramp voltage is applied to the Y electrode, and is formed in the cell while the falling ramp voltage is applied to the scan electrode. The weak wall voltage causes a slight discharge from the X electrode and the address electrode to the Y electrode to initialize all the cells.

Next, in the address period, the positive voltage Va is applied to the address electrode of the cell to be selected and the voltage VscL is applied to the Y electrode. Then, an address discharge occurs between the address electrode and the Y electrode and between the X electrode and the Y electrode by the wall voltage and the positive voltage Va caused by the wall charge formed in the reset period. This discharge accumulates positive wall charges on the Y electrode and negative wall charges on the X electrode and the address electrode. In the selected cell among the cells in which the wall charges are accumulated by the address discharge, the sustain discharge is caused by one sustain discharge pulse applied to the Y electrode in the sustain period.

On the other hand, since the sustain discharge is caused by the unit light in the sustain period of the subfield SF1, the wall charge may be unstable as compared with the case where several sustain discharges occur. Therefore, in the subsequent reset period of the next subfield SF2, the main reset waveform is applied to the Y electrode to initialize all the cells, and the same waveform as the subfield SF1 is applied in the address period and the sustain period.

Similarly, in the sustain period of the subfield SF2, since sustain discharge has occurred by one sustain discharge pulse, the main reset waveform is applied to the Y electrode in the reset period of the subfield SF3. The same waveform as the subfield SF1 is applied, and the main reset waveform is applied to the Y electrode in the reset period of the subfield SF4. In the sustain period of the subfield SF4, a sustain discharge pulse is alternately applied to the X electrode and the Y electrode to apply two or more sustain discharge pulses to each of the X electrode and the Y electrode, and a reset period of the subfield SF5. An auxiliary reset waveform having only a falling ramp waveform that decreases from the voltage Vs to the voltage VscL is applied to the Y electrode.

However, in the case where the discharge by the unit light occurs in the sustain period as described above, the light due to the discharge is weak so that the light that cannot be ignored by the reset discharge caused by the main reset waveform applied in the reset period (this is called background light). ) Occurs. As described above, when background light is counted, it becomes difficult to display gradation by unit light in the sustain period.

Accordingly, the second embodiment of the present invention proposes a method for preventing low discharge in a subsequent subfield while minimizing background light when sustain discharge by unit light occurs in a continuous low gradation subfield.

3 illustrates a driving waveform of the plasma display device according to the second exemplary embodiment of the present invention, in which discharge by unit light occurs continuously in the sustain periods of the first, second and third subfields. .

As shown in FIG. 3, according to the driving method of the plasma display device according to the first exemplary embodiment of the present invention, in the reset period of the subfield SF1, the voltage slowly rises from the voltage Vs to the voltage Vset at the Y electrode, and at the voltage Vs. A main reset waveform is applied which slowly drops to the VscL voltage. At this time, a reference voltage (0V) is applied to the address electrode, a reference voltage (0V) is applied to the X electrode when a rising ramp voltage is applied to the Y electrode, and a X-terminal is applied to the X electrode when a falling ramp voltage is applied to the Y electrode. Ve voltage is applied.

When the main reset waveform is applied as described above, weak discharge occurs from the Y electrode to the address electrode and the X electrode while the rising ramp voltage is applied to the Y electrode, and is formed in the cell while the falling ramp voltage is applied to the scan electrode. The weak wall voltage causes a slight discharge from the X electrode and the address electrode to the Y electrode to initialize all the cells.

Next, in the address period, the positive voltage Va is applied to the address electrode of the cell to be selected and the voltage VscL is applied to the Y electrode. Then, an address discharge occurs between the address electrode and the Y electrode and between the X electrode and the Y electrode by the wall voltage and the positive voltage Va caused by the wall charge formed in the reset period. This discharge accumulates positive wall charges on the Y electrode and negative wall charges on the X electrode and the address electrode. In the selected cell among the cells in which the wall charges are accumulated by the address discharge, the sustain discharge is caused by one sustain discharge pulse applied to the Y electrode in the sustain period.

Next, in the reset period of the subfield SF2, an auxiliary reset waveform having only a falling ramp waveform decreasing from the voltage Vs to the voltage VscL is applied to the Y electrode. Next, the same waveform as the subfield SF1 is applied to the address period and the sustain period.

Similarly, the auxiliary reset waveform is applied to the Y electrode in the reset period of the subfield SF3, and the same waveform as the subfield SF1 is applied to the address period and the sustain period.

As described above, if the auxiliary reset waveform is applied in the reset period of the next subfield SF2 and SF3 while only one sustain discharge pulse is applied to the Y electrode in the sustain period of the subfields SF1 and SF2, the reset discharge is properly performed. Since it does not occur, low discharge may occur in the address period and the sustain period. However, in the subfields SF1 to SF3, since the sustain discharge is generated by the unit light, the amount of light is not very low and only one subfield of low gradation is turned on by itself. Low discharge at has little effect on the overall brightness.

However, in the sustain period of the subfield SF4, the sustain discharge pulse is applied to the X electrode and the Y electrode alternately, so that at least two sustain discharge pulses are applied to the X electrode and the Y electrode, respectively. The amount of light generated by this cannot be ignored. Therefore, in the reset period of the subfield SF4, the main reset waveform is applied to initialize all the cells. Then, stable discharge normally occurs in the address period and the sustain period of the subfield SF4.

As described above, according to an exemplary embodiment of the present invention, when only one sustain discharge pulse is applied during a continuous subfield displaying low gray scales by analyzing subfield data for each gray level, the sub sub-field to which one sustain discharge pulse is applied last is applied. Since the main reset waveform is applied in the reset period of the subfield immediately following the field, the wall voltage can be adjusted according to the address condition after the wall charges are sufficiently accumulated on the Y electrode in the reset period. Therefore, there is little chance of low discharge occurring in the address period and the sustain period.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

As described above, according to the present invention, when the sustain discharge by the unit light occurs in the continuous low gradation subfields, the reset period of the subfield subsequent to the subfield where the sustain discharge by the unit light has occurred lastly. By applying the main reset waveform, it is possible to prevent low discharge and false discharge occurring in subsequent subfields.

Claims (7)

A method of driving a plasma display device comprising a plurality of first electrodes, a plurality of second electrodes, and a plurality of third electrodes formed in a direction crossing the first and second electrodes, Applying a sustain discharge pulse to the first electrode once in a sustain period of a first subfield having a minimum weight; In the reset period of the at least one second subfield continuous in time to the minimum weight subfield, the voltage difference between the first electrode and the second electrode and the voltage difference between the first electrode and the third electrode are gradually decreased. Making a step; Applying a sustain discharge pulse to the first electrode once in a sustain period of the second subfield; In the reset period of the third subfield continuous to the second subfield, the voltage difference between the first electrode and the second electrode and the voltage difference between the first electrode and the third electrode are gradually increased. Progressively decreasing after; And Alternately applying a sustain discharge pulse to the first electrode and the second electrode in the sustain period of the third subfield, and applying a sustain discharge pulse to the first electrode a plurality of times; Method of driving a plasma display device comprising a. The method of claim 1, In the reset period of the first subfield, gradually increasing the voltage difference between the first electrode and the second electrode, and gradually decreasing the voltage difference between the first electrode and the third electrode, respectively. The driving method of the plasma display device further comprising. The method according to claim 1 or 2, In the reset period of the first to third subfields, the voltage of the first electrode is gradually lowered from the first voltage to the second voltage while the voltages of the second electrode and the third electrode are biased to a predetermined voltage. A method of driving a plasma display device. The method of claim 3, In the reset period of the second subfield, the first voltage is the voltage of the sustain discharge pulse applied to the first electrode in the sustain period of the first subfield. A method of driving a plasma display device. A plasma display panel including a plurality of discharge cells; A control unit for dividing the number of sustain discharge pulses according to the load ratio and one frame into a plurality of subfields having respective weights, and determining the number of application of sustain discharge pulses for each subfield for gray scale display; And A driving circuit for supplying a driving voltage to an electrode forming the discharge cell by a control signal of the controller; The drive circuit, In the reset period of the first subfield having the minimum weight, the states of the discharge cells in which sustain discharge has occurred and the discharge cells in which sustain discharge has not occurred are initialized, The state of the discharge cell in which sustain discharge has occurred in the immediately preceding subfield in the reset period of at least one second subfield consecutive in time in which the number of sustain discharge pulses applied to each subfield among the subfields except the first subfield is 1; To initialize In the reset period of the third subfield located after the plurality of consecutive subfields, the states of the discharge cells in which sustain discharge has occurred in the immediately preceding subfield and the discharge cells in which sustain discharge has not occurred are initialized. Plasma display device. The method of claim 5, The drive circuit, In the sustain period of the third subfield, a sustain discharge pulse is alternately applied to two electrodes forming the discharge cell, and a sustain discharge pulse is applied to each electrode at least twice. The method according to claim 5 or 6, The drive circuit, In the reset period of the first and third subfields, the voltage difference between the two electrodes forming the discharge cell is gradually increased and then gradually decreased, In the reset period of the second subfield, the voltage difference between the two electrodes forming the discharge cell is gradually decreased. Plasma display device.

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