KR100740103B1 - Plasma display and driving method thereof - Google Patents

Abstract

In a plasma display device, a plurality of subfields are divided into a plurality of subfield groups and a plurality of row electrodes are driven into a plurality of row groups. In each subfield of the first subfield group, light emitting cells are selected from the plurality of discharge cells during the first address period, and the light emitting cells are sustained and discharged during the first sustain period. In a first subfield of a second subfield group, a light emitting cell is selected from discharge cells of each row group during a second address period for each row group of the plurality of row groups, and between two adjacent second address periods. Discharge discharge cells in the light emitting cell states of the plurality of row groups during the second sustain period, wherein the third cell is configured to generate a third discharge cell for each row group of the plurality of row groups in the second subfield of the second subfield group. A non-light emitting cell is selected from the light emitting cells of each row group during an address period, and the sustain cells are discharged in the discharge cells of the light emitting cell states of the plurality of row groups during a third sustain period located between two adjacent third address periods. Let's do it. At this time, by expressing the gradation above the specific gradation only by the second subfield group, address power consumption is reduced.

PDP, electrode, discharge, selective write, selective erase, reset, gradation, dither

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 is a diagram schematically illustrating a method of driving a plasma display device according to a first embodiment of the present invention.

3 is a view illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 2.

4 is a diagram illustrating a gray scale expression method according to the driving method of FIG. 2.

5 is a diagram schematically illustrating a method of driving a plasma display device according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a gray scale expression method according to the driving method of FIG. 5.

FIG. 7 is a diagram illustrating a gray scale expression method according to a third exemplary embodiment of the present invention using the driving method illustrated in FIG. 5.

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, a plurality of discharge cells are arranged in a matrix form.

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. Each subfield includes a reset period, an address period, and a sustain period. The reset period is a period for initializing the state of the discharge cells in order to stably perform the next address discharge, and the address period is a period for selecting discharge cells to emit light and discharge cells not to emit light among the plurality of discharge cells. The sustain period is a period in which sustain discharge is performed on the discharge cells selected in the address period in order to actually display an image.

At this time, there is a method of performing the sustain discharge operation on all the discharge cells after completing the addressing operation for all the discharge cells in each subfield, that is, a method of temporally separating the address period and the sustain period. This is generally referred to as an address display period separation (ADS) method. The ADS method can be easily implemented, but since addressing operations are sequentially performed on all discharge cells, address discharge may not occur well due to a lack of priming particles in the discharge cells in the discharge cells that are addressed later in time. Therefore, the width of the scan pulses sequentially applied to the scan electrodes is inevitably increased for stable address discharge, thereby increasing the length of the address period. As a result, the length of the subfield is long, which limits the number of subfields that can be used in one field.

Unlike the ADS method, an address pulse of each line is inserted between successive sustain discharge pulses to perform an addressing operation on another line while sustain discharge is performed on one line. That is, the method does not separate the address period and the sustain period, which is generally referred to as an address while display (AWD) method. In this AWD method, since the address pulse and the sustain discharge pulse proceed in succession, a reset pulse for initialization must be entered between these successive pulses. Therefore, a reset pulse that requires a long time cannot be used. That is, since the reset discharge must be performed with a strong discharge, the black screen looks bright and the contrast ratio worsens.

In addition, both the ADS method and the AWD method use subfields having different weights for gray scale representation. For example, in the case of using a weighted subfield in the form of a power of 2, a pseudo contour is generated when one discharge cell expresses 127 gray levels and 128 gray levels, respectively, in two consecutive frames.

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 scanning at high speed and improving contrast ratio. Another object of the present invention is to provide a plasma display device and a driving method thereof, which can increase the number of gray scales that can reduce and express pseudo contours and can reduce address power consumption.

According to one aspect of the present invention, in a plasma display device including a plurality of row electrodes and a plurality of column electrodes, and a plurality of discharge cells defined by the row electrode and the column electrode, one field is divided into a plurality of subfields. A driving method for expressing gradation by dividing by is provided. The driving method includes: a first subfield group including the plurality of row electrodes divided into a plurality of row groups, the plurality of subfields into the plurality of subfield groups, and a plurality of subfields having respective weights. In each subfield of, selecting a light emitting cell from the plurality of discharge cells and sustaining discharge of the light emitting cell, in the first subfield of the second subfield group including a plurality of subfields having the same weight, wherein Selecting the light emitting cells from the discharge cells of the first row group among the plurality of row groups and sustain-discharging the discharge cells in the light emitting cell states of the plurality of row groups, and in the second subfield of the second subfield group, Selecting a non-light emitting cell from the light emitting cells of the first row group among the plurality of row groups, and performing sustain discharge of the discharge cells in the light emitting cell state of the plurality of row groups To include, and only expresses the above specified gradation gray scale and the second subfield group.

In this case, the gradation below the specific gradation is expressed by a combination of the first subfield group and the second subfield group.

According to another feature of the present invention, a plasma display device including a plasma display panel, a controller, and a driver is provided. The plasma display panel includes a plurality of row electrodes for performing a display operation and a plurality of column electrodes formed in a direction crossing the row electrodes, and a plurality of discharge cells are formed by the plurality of row electrodes and the plurality of column electrodes. do. The controller controls the plurality of row electrodes to be divided into a plurality of row groups and to divide the plurality of subfields into a plurality of subfield groups to express gray levels. The driver selects light emitting cells from the plurality of discharge cells during a first address period in each subfield of the first subfield group including a plurality of subfills having respective weights, and emits the light emitting cells during a first sustain period. In the first subfield of the second subfield group including the plurality of subfields having the same weight, the discharge of each row group during the second address period for each row group of the plurality of row groups Selecting a light emitting cell from a cell, sustain discharge-discharging discharge cells in the light-emitting cell state of the plurality of row groups during a second sustain period positioned between two adjacent second address periods; In the second subfield, the non-light emitting cells are selected from the light emitting cells of each row group during the third address period for each row group of the plurality of row groups. The discharge cells in the light emitting cell states of the plurality of row groups are sustained and discharged during the third sustaining period located between two adjacent third address periods. In this case, the controller expresses a gray level of a specific gray level or more only as the second subfield group.

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.

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 X electrode and the Y electrode perform a display operation for displaying an image in the sustain period. 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. In this case, the controller 200 divides and drives one frame into a plurality of subfields having respective luminance weights, and the plurality of subfields are driven into a plurality of groups again. In addition, the plurality of X electrodes and the Y electrodes are divided into a plurality of groups and driven.

The address electrode driver 300 receives the A electrode driving control signal from the controller 200 and applies a driving voltage to the A electrodes A1 to Am.

The scan electrode driver 400 receives the Y electrode driving control signal from the controller 200 and applies a driving voltage to the Y electrodes Y1 to Yn.

The sustain electrode driver 500 receives the X electrode driving control signal from the controller 200 and applies a driving voltage to the X electrodes X1 to Xn.

In the following description, the X electrode and the Y electrode extending in pairs with each other in the row direction are referred to as row electrodes, and the A electrode extending in the column direction is referred to as column electrodes.

Next, a driving method of the plasma display device according to the first embodiment of the present invention will be described in detail with reference to FIG. 2. In the first embodiment of the present invention, the lengths of the sustain periods applied after the address period of each row group are the same, and the sustain periods have the same length in all the subfields.

2 is a view schematically illustrating a method of driving a plasma display device according to a first embodiment of the present invention.

As shown in Fig. 2, one field consists of a plurality of subfields SF11-SF1L, and the plurality of row electrodes X1 to Xn and Y1 to Yn are divided into a plurality of row groups. In FIG. 2, it is assumed that the plurality of row electrodes X1 to Xn and Y1 to Yn are grouped in a physical arrangement and divided into eight groups. At this time, the first to jth row electrodes are set to the first row group G ₁ , and the (j + 1) th to (2j) th row electrodes are set to the second row group G ₂ . In this manner, the (7j + 1) th to nth row electrodes are set to the eighth row group G ₈ (where j = n / 8). Alternatively, the row electrodes spaced apart at regular intervals may be set as a group, and the row electrodes may be grouped in an irregular manner as necessary.

And the first sub-field (SF11) is divided into a reset period (R11), an address period (WA11 ₁ ~WA11 ₈₎ and made of a holding period (S11 ₁ ~S11 _8), a first address period of the subfield (SF11) (WA11 _{1 to} WA11 ₈ are made of a selective write address. The second subfield to the last subfield SF12 to SF1L consist of address periods EA12 _{1 to} EA1L ₈ and sustain periods S12 _{1 to} S1L ₈ , and from the second subfield to the last subfield SF12 to SF1L. The address periods EA12 _{1 to} EA1L ₈ have a selective erase method. As described above, in the first embodiment, the plurality of subfields SF11 to SF1L include a subfield group of the selective writing method and a subfield group of the selective erasing method.

There are a selective writing method and a selective erasing method for selecting a discharge cell to emit light and a discharge cell not to emit light among a plurality of discharge cells. The selective write method is a method of selecting a discharge cell to emit light to form a constant wall voltage, and the selective erasing method is a method of selecting a discharge cell that will not emit light to erase a wall voltage already formed. That is, the selective write method is a method of address discharge of a cell in a non-light emitting cell state to form a wall charge and set it to a light emitting cell state, and the selective erasing method of addressing a cell in a light emitting cell state to discharge a wall charge already formed. It is a method of erasing and setting to a non-light emitting cell state. In the subfield having the address period of the selective writing method, a reset period for initializing the light emitting cells to non-light emitting cells is generally formed immediately before the address period. In the following, the address discharge for forming the wall charge in the selective writing method is called "write discharge", and the address discharge for erasing the wall charge in the selective erasing method is called "erasure discharge".

Referring to FIG. 2 again, the first subfield SF11 having the address period of the selective writing method has a reset period R11 for initializing all discharge cells and setting them to the non-light emitting cell state. That is, in the reset period R11 of the first subfield SF11, first, the discharge cells of all the row groups G _{1 to} G ₈ are initialized and set to the non-light emitting cell state, and in the address periods WA11 _{1 to} WA11 ₈ . It is set in a state where address discharge is possible.

Then, the first sub-field (SF11) in the first to eighth row groups during the address period (WA11 ₁ ~WA11 _8), and a sustain period (S11 ₁ ~S11 ₈₎ of the (G ₁ ~G ₈₎ are performed sequentially. That is, the i is the sustain period (S11 _i) of the line group (G _i) the address period (WA11 _i) is performed, the i group (G _i) is performed after the. Subsequently, the address period WA11 _{i + 1} and the sustain period S11 _{i + 1 of} the (i + 1) th row group G _{i + 1} are performed.

Specifically, in the address period WA11 ₁ , the discharge cells set as the light emitting cells among the discharge cells of the first row group G ₁ are write-discharged to form wall charges, and the first row group G in the sustain period S11 ₁ . The light emitting cell of ₁ ) is sustained and discharged. Subsequently, in the address period WA11 ₂ , wall discharge is formed by writing and discharging the discharge cells set as light emitting cells among the discharge cells of the second row group G ₂ , and in the sustain period S11 ₂ , the second row group G _{2 is formed.} Sustain light discharge cell. At this time, sustain discharge also occurs in the light emitting cells of the first row group G ₁ . Similarly, for the other line group (G ₃ ~G ₈₎ during the address period (WA11 ₃ ~WA11 _8), and a sustain period (S11 ₃ ~S11 ₈₎ it is performed.

At this time, the i group (G _i) a sustain period (S11 _i) in the i th row group (G _i) the light-emitting cell and the first through the (i-1) line group (G ₁ ~G _i-1) of the The sustain discharge also occurs in the light emitting cell. The discharge cells of the _i th row group G _i set as light emitting cells in the first subfield SF11 are held just before the address period EA12 _i of the i th row group G _i of the second subfield SF12. The discharge is sustained until the periods S11 _{i to} S11 ₈ and S12 _{1 to} S12 _i-1 . That is, in the light emitting cells of the _i th row group G _i , sustain discharge occurs for a total of 8 sustain periods.

The address period of the next, the first to eighth row group in the second sub-field (SF12) having an address period of the selective erasing mode _{(G 1 ~G 8) (EA12} 1 ~EA12 8) , and a sustain period (S12 ₁ ~S12 ₈ ) is performed sequentially. That is, the i is the sustain period (S12 _i) of the line group (G _i) the address period (EA12 _i) is performed, the i group (G _i) is performed after the. Subsequently, the address period EA12 _{i + 1} and the sustain period S12 _{i + 1 of} the (i + 1) th row group G _{i + 1} are performed.

Specifically, in the address period EA12 ₁ , the discharge cells set as the non-light emitting cells of the light emitting cells of the first row group G ₁ are erased and discharged to erase the wall charges, and in the sustain period S12 ₁ , the first row group ( The remaining light emitting cells of G ₁ ) are sustained and discharged. Subsequently, in the address period EA12 ₂ , the discharge cells set as the non-light emitting cells of the light emitting cells of the second row group G ₂ are erased and discharged to erase the wall charges, and the second row group G is maintained in the sustain period S12 ₂ . The remaining light emitting cells in ₂ ) are sustained and discharged. At this time, sustain discharge also occurs in the light emitting cells of the first row group G ₁ . Similarly, remaining lines in the group (G ₃ ~G ₈₎ about the address period (EA12 ₃ ~EA12 _8), and a sustain period (S12 ₃ ~S12 ₈₎ is performed.

At this time, the i group (G _i) a sustain period (S12 _i) in the i th row group (G _i) the light-emitting cell and the first through the (i-1) line group (G ₁ ~G _i-1) of the The sustain discharge also occurs in the light emitting cell. And the i-th row group (G _i) of the light-emitting cell denotes a third sub-field (SF13) the i-th row group (G _i) the address period (EA13 _i) a sustain period of the immediately preceding _(i ~S11 ₈ S11, S12 ~ ₁ of Sustain discharge until S12 _i-1 ). That is, in the light emitting cells of the _i th row group G _i , sustain discharge occurs for a total of 8 sustain periods.

The remaining subfields SF13 to SF1L having the address period of the selective erasing method also have the same address periods EA13 _{1 to} EA13 ₈ , for each row group G _{1 to} G ₈ , similarly to the second subfield SF12 described above. ..., EA1L _{1 to} EA1L ₈ ) and the sustain periods S13 _{1 to} S13 ₈ , ..., S1L _{1 to} S1L ₈ are performed. In this way, the discharge cells set to the light emitting cells by the write discharge in the first subfield SF11 continue until they are set to the non-light emitting cells by the erase discharge in the address periods EA12 _{i to} EA1L _i of the subsequent subfields SF12 to SF1L. When the sustain discharge is performed and the non-light emitting cell becomes the erase discharge, the sustain discharge is not started from the subfield.

In the last subfield SF1L, in order to make the number of sustain discharges in each row group G _{1 to} G ₈ equal to each other, the _second subfield SF1L is once to each of the second to eighth row groups G _{2 to} G ₈ . Seven maintenance periods SA1 _{2 to} SA1 ₈ are additionally performed.

To this end, additional retention periods SA1 _{2 to} SA1 ₈ are formed in the last subfield SF1L for the second to eighth row groups G _{2 to} G ₈ , respectively. And additional sustain period (SA1 ₂ ~SA1 ₈₎ additional sustain period (SA1 ₂ ~SA1 ₈ of 8 times the sustain period in order to prevent sustain discharge in the groups of rows are performed, each row group (G ₂ ~G ₈₎ in The erasing periods ER1 _{1 to} ER1 ₇ for erasing the wall charges formed in the immediately preceding row groups G _{1 to} G ₇ are formed immediately before.

On the other hand, the eighth row group is (G ₈₎ may be formed in the erase period (ER1 ₈₎ for erasing wall charges in the additional sustain period (SA1 _8), even after the eighth row group (G ₈₎ a. In addition, since the reset period R11 is performed in the first subfield SF11 of the subsequent field, the erase period ER1 ₈ of the eighth row group G ₈ may not be formed. The erase operations in the erase periods ER1 _{1 to} ER1 ₈ may be sequentially performed on each row electrode of each row group as in the address period, or may be simultaneously performed on all row electrodes of each row group.

Specifically, after the sustain period S1L ₈ of the eighth row group G ₈ of the last subfield SF1L is performed, all discharge cells of the first row group G _{1 are} erased in the erase period ER1 ₁ . Eliminates wall charges that have formed. Then, in the sustain period SA1 ₂ , the light emitting cells of the second to eighth row groups G _{2 to} G ₈ are sustained and discharged. Then, after erasing the wall charges formed in all the discharge cells of the second row group G ₂ in the erasing period ER1 ₂ , the third to eighth row groups G ₃ in the sustaining period SA1 ₃ . It keeps discharging the light emitting cells of ~G _8). In this way, it is performed until the maintenance period SA1 ₈ . In this way, the number of sustain discharges in the light emitting cells of each row group G _{1 to} G ₈ is the same.

Next, a driving waveform used in the driving method of the plasma display device according to the first embodiment of the present invention will be described in detail with reference to FIG. 3.

3 is a view illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 2. In FIG. 3, only the first and second row groups G ₁ and G ₂ and the first and second subfields SF11 and SF12 are illustrated for convenience of description, and the driving waveforms applied to the A electrode are not shown. The description of the driving waveform applied to the A electrode is also omitted.

As shown in FIG. 3, in the reset period R11 of the first subfield SF11, Y of all the row groups G ₁ and G ₂ in the state where a reference voltage (0 V in FIG. 3) is applied to the X electrode. The voltage of the electrode is gradually increased from Vs voltage to Vset voltage. Then, a weak reset discharge occurs between the Y electrode and the X electrode while the voltage of the Y electrode increases, and wall charges are formed in the discharge cells of all the row groups G ₁ and G ₂ . Subsequently, with the Vs voltage applied to the X electrode, the voltages of the Y electrodes of all the row groups G ₁ and G ₂ are gradually decreased from the Vs voltage to the Vnf voltage. Then, while a weak reset discharge occurs between the Y electrode and the X electrode while the voltage of the Y electrode decreases, the wall charges formed in the discharge cells of all the row groups G ₁ and G ₂ are erased and initialized to the non-light emitting cell. In general, the magnitude of the voltage (Vnf-Vs) 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, thereby preventing the non-light emitting cell in which the address discharge has not occurred in the address period from being erroneously discharged in the sustain period.

In the address period WA11 ₁ , while the Vs voltage is applied to the X electrode, first, a scan pulse of the VscL1 voltage is sequentially applied to the plurality of Y electrodes of the first row group G1. At this time, an address pulse (not shown) having a positive voltage is applied to the A electrode of the discharge cell to emit light among the discharge cells formed by the Y electrode to which the scan pulse is applied. Then, write discharge occurs in the discharge cells to which the VscL1 voltage of the scan pulse and the positive voltage of the address pulse are applied, and wall voltages are formed on the X and Y electrodes to form light emitting cells. The Y electrode to which the scan pulse is not applied applies a VscH1 voltage higher than the voltage of the scan pulse, and a reference voltage is applied to the A electrode to which the address pulse is not applied, although not shown. At this time, the voltage VscH1 is also applied to the Y electrodes of the second to eighth row groups G _{2 to} G ₈ .

Next, in the sustain period S11 ₁ , the sustain discharge pulse of the voltage Vs is applied to the Y electrodes of all the row groups G ₁ and G ₂ to sustain discharge the light emitting cells. Subsequently, sustain discharge pulses of the voltage Vs are applied to the X electrodes of all the row groups G ₁ and G ₂ to sustain discharge the light emitting cells. In this case, first, because only the cells are light emitting cells, the discharge written in the address period (WA11 ₁₎ of the line group (G ₁₎ takes place, the first line group during the address period of the (G ₁₎ (WA11 ₁₎ only happened cell address discharge in Sustain discharge occurs.

While the sustain discharge pulse is applied to the X electrode, in the address period WA11 ₂ , the scan pulses of the VscL1 voltage are sequentially applied to the plurality of Y electrodes of the second row group G ₂ while the Vs voltage is applied to the X electrode. Is applied, an address pulse having a positive voltage is applied to the A electrode of the discharge cell to emit light among the discharge cells formed by the Y electrode to which the scan pulse is applied, and the cell in the non-light emitting cell state is discharged and set as the light emitting cell. do.

Next, in the sustain period S11 ₂ , the sustain discharge pulse of the voltage Vs is applied to the Y electrodes of all the row groups G ₁ and G ₂ to sustain discharge the light emitting cells. Subsequently, sustain discharge pulses of the voltage Vs are applied to the X electrodes of all the row groups G ₁ and G ₂ to sustain discharge the light emitting cells. In this case, the first and second groups of rows, so (G _1, G ₂₎ the address period, cells are light-emitting cells are discharged written in (WA11 _1, WA11 ₂₎ takes place in the first and second row groups (G _1, G ₂ Sustain discharge occurs in a cell in which address discharge has occurred in the address periods WA11 ₁ and WA11 ₂ . In this manner, an address period and a sustain period are performed for each row group in the first subfield SF11.

Next, in the address period EA12 ₁ of the second subfield SF12, scan pulses of the VscL2 voltage are sequentially applied to the plurality of Y electrodes of the first row group G ₁ while the reference voltage is applied to the X electrode. do. At this time, an address pulse (not shown) having a positive voltage is applied to the A electrode of the cell to be selected as the non-light emitting cell among the light emitting cells (cells in which sustain discharge has occurred in the first subfield) formed by the Y electrode to which the scan pulse is applied. do. A VscH2 voltage higher than the VscL2 voltage is applied to the Y electrode to which the scan pulse is not applied, and a reference voltage is applied to the A electrode to which the address pulse is not applied. Then, erase discharge occurs in the light emitting cell to which the VscL2 voltage of the scan pulse and the positive voltage of the address pulse are applied, so that the wall charges formed on the X electrode and the Y electrode are erased and set as the non-light emitting cell.

In the light emitting cell of the first subfield SF11, the cell in which the erasure discharge has not occurred in the address period EA12 ₁ of the second subfield SF12 is the light emitting cell of the second subfield SF12, and thus, the second subfield. In the sustain period S12 ₁ of the SF12, a sustain discharge pulse having a voltage of Vs is first applied to the X electrodes of the first and second row groups G ₁ and G _{2 to} generate sustain discharge in the light emitting cell, and then to the first electrode. And a Vs voltage is applied to the Y electrodes of the second row groups G ₁ and G ₂ to generate sustain discharge in the light emitting cells.

Then, in the address period EA12 ₂ , while a reference voltage is applied to the X electrode, a scan pulse of a VscL2 voltage, which is a negative voltage, is sequentially applied to the plurality of Y electrodes of the second row group G ₂ , and the scan is performed. An address pulse (not shown) having a positive voltage is applied to the A electrode of the cell to be selected as the non-light emitting cell among the light emitting cells (cells in which sustain discharge has occurred in the first subfield) formed by the Y electrode to which the pulse is applied. Then, erase discharge occurs in the light emitting cell to which the VscL2 voltage of the scan pulse and the positive voltage of the address pulse are applied, so that the wall charges formed on the X electrode and the Y electrode are erased and set as the non-light emitting cell.

Subsequently, in the sustain period S12 ₂ , sustain discharge pulses of the voltage Vs are first applied to the X electrodes of the first and second row groups G ₁ and G _{2 to} generate sustain discharge in the light emitting cells, and then the first and second electrodes. The voltage Vs is applied to the Y electrodes of the row groups G ₁ and G ₂ to cause sustain discharge in the light emitting cells. In this manner, the address period and the sustain period are performed for the remaining row groups G _{3 to} G ₄ .

As described above, in the first embodiment of the present invention, since the address period is formed between the sustain periods of each row group, the priming particles formed in the sustain period can be sufficiently utilized in the address period, so that the scan pulse can be shortened to perform high-speed scanning. Can be. In addition, since the voltage gradually increases and the voltage gradually decreases in the reset period, no strong discharge occurs in the reset period, and the contrast ratio can be increased because one reset period is performed for one field for every row group.

Next, a method of expressing gray scales by the driving method of FIG. 2 will be described with reference to FIG. 4.

4 is a diagram illustrating a gray scale expression method according to the driving method of FIG. 2. In FIG. 4, one field includes 31 subfields. In FIG. 4, "SW" indicates that the non-light emitting cell is set as the light emitting cell because a write discharge occurs in the corresponding subfield, and "SE" indicates that the light emitting cell is set as the non-light emitting cell because the erase discharge occurs in the corresponding subfield. In addition, "o" indicates a subfield in the light emitting cell state. The gray level when sustain discharge occurs only in one subfield is referred to as 1.

As shown in Fig. 4, when a non-light emitting cell is made in the address period WA11 _i of the first subfield SF11, sustain discharge does not occur in the sustain period S11 _i , and is also retained in the next subfields SF12 to SF1L. Since no discharge occurs, zero gradation is expressed. When a light emitting cell is generated in the address period WA11 _{i of} the first subfield SF11, since sustain discharge occurs in the first subfield SF11, one gray level can be expressed. Next, when an erase discharge occurs in the second subfield SF12 to become a non-light emitting cell, sustain discharge does not occur from the second subfield SF12. In addition, if the erase discharge does not occur in the second subfield SF12, since it is a light emitting cell, sustain discharge also occurs in the second subfield SF12, thereby expressing one gray scale. That is, the discharge cells which become light emitting cells in the first subfield SF11 and become non-light emitting cells in the K-th subfield SF1K are the first to the (K-1) th subfield SF1 (K). Since sustain discharge continues in -1)), the (K-1) gradation is finally expressed. That is, when one field is composed of 31 subfields as shown in FIG. 3, 32 tones can be expressed from 0 to 31 tones.

As described above, in the first embodiment, gray scales are represented by subfields that are turned on continuously from the first subfield, so that a pseudo outline does not occur. When one or more gray levels are displayed in the first embodiment, after the write discharge occurs in the address period of the first subfield SF11, the erasure discharge occurs in the address period of the subfield of the corresponding gray level. That is, no matter what gray level is represented in the first subfield, two or fewer discharges occur in the address period. Therefore, according to the first embodiment, the number of address discharges in the address period is reduced, so that power consumption due to the address discharges is reduced. However, since the number of subfields that can fit in one field is limited, the number of gradations that can be expressed only by the subfields is limited.

In this case, in order to increase the number of gray levels that can be expressed in one field, the weight of each subfield may be set to a number other than one. For example, when a field is composed of 31 subfields, when the weight of each subfield is set to 8, a gray level corresponding to a multiple of 8 from 0 to 248 (= 8 × 31) grays can be expressed. . In this case, gray levels that are not integer multiples of 8 may be expressed using dithering. Such dithering is a technique of expressing an average of close to the gray scale to be expressed in a certain area by combining a specific gray scale. For example, gray scales between 0 gray scales and 8 gray scales may be expressed using 0 gray scales and 8 gray scales in a predetermined pixel area. However, the human eye recognizes the gray level difference in the low gray level better than the gray level difference in the high gray level. Therefore, when the low gray level is represented by dithering rather than a combination of subfields, there is a problem that the low gray level expressive power is lowered.

Hereinafter, a method of increasing the number of gray levels that can be expressed by a combination of subfields in one field and improving the expressive power of low gray levels will be described in detail with reference to FIG. 5.

5 is a diagram schematically illustrating a method of driving a plasma display device according to a second embodiment of the present invention.

As shown in FIG. 5, the driving method according to the second embodiment of the present invention divides a plurality of subfields SF21 to SF2M into two groups of subfields. In FIG. 5, the subfields of the first group include first to fifth subfields SF21 to SF25. In this case, the subfields SF21 to SF25 of the first group are formed temporally before the subfields SF26 to SF2M of the second group and include at least one subfield having respective weights. The address periods WA21 to WA25 of the subfields of the first group are made of a selective write address. In the subfields SF21 to SF25 of the first group, one row electrode is not grouped. The light emitting cells are selected from among the discharge cells formed by the plurality of row electrodes during the address period. Since the subfields SF26 to SF2M of the second group are the same as the subfields SF11 to SF1L in the first embodiment, the description of the subfields SF26 to SF2M of the second group will be omitted below.

Specifically, in the reset periods R21 to R25 of the respective subfields SF21 to SF25 of the first group, the discharge cells of all the row electrodes are initialized and set to the non-light emitting cell state, and the write discharge is performed in the address periods WA21 to WA25. Set this to a state that is possible.

Subsequently, in the address periods WA21 to WA25 of the first subfield SF21, the discharge cells set as the light emitting cells are discharged from the discharge cells of the plurality of row electrodes to form wall discharge. That is, after writing discharge is sequentially performed on the plurality of row electrodes in each address period WA21 to WA25, after the light emitting cells are selected, each sustain period S21 to S25 is performed to generate sustain discharge in the light emitting cells.

In addition, a plurality of row electrodes may be divided into a plurality of row groups in each of the subfields SF21 to SF25 of the first group to be driven. By the way, when a plurality of row electrodes are divided into a plurality of row groups, a sustain period must be performed for each row group, respectively. Then, when the total row group is divided into eight, a total of eight retention periods are performed. As a result, the length of the total sustain period in one subfield is long, which limits the number of subfields that can be used in one field. However, when the plurality of row electrodes are driven without being grouped as in the second embodiment of the present invention, one sustain period (S21 to SF25) is performed in each subfield SF21 to SF25 of the first group. Can be reduced.

The subfields SF21 to SF25 of the first group have reset periods R21 to R25, respectively, so that the current cell can be set as a light emitting cell irrespective of the cell state in the immediately preceding subfield. Therefore, the discharge cells in the subfields SF21 to SF25 of the first group can be selectively sustained and discharged. At this time, when the lengths of the relative holding periods S21 to S25 of the subfields SF21 to SF25 of the first group, that is, the weights are 1, 2, 4, 8 and 16, respectively, the subfields SF21 to the first group SF25) can express 0 to 31 gradations, that is, 32 kinds of gradations in total. At this time, the weight of each subfield SF21 to SF25 of the first group corresponds to the length of one sustain period S21 to S25 of the corresponding subfield, and the weight of each subfield SF26 to SF2M of the second group is Corresponds to the sum of the lengths of the _eight sustaining periods S2N _{1 to} S2N ₈ (where N is an integer between 6 and M). The length of the sustain period S21 of the first subfield SF21 of the first group is the sustain period S26 of one row group in any one subfield of the second group, for example, the sixth subfield SF26. _Is equal to 1/4 of the length of ₁ ).

In the subfields SF26 to SF2M of the second group, gray levels are represented by subfields that are sequentially turned on from the sixth subfield SF26 as described above. Therefore, the gray level in one field may be expressed by the sum of the gray level represented in the subfields SF21 to SF25 of the first group and the gray level represented in the subfields SF26 to SF2M of the second group.

FIG. 6 is a diagram illustrating a gray scale expression method according to the driving method of FIG. 5. In FIG. 6, one field is composed of 12 subfields.

As shown in FIG. 6, the subfields of the first group include subfields SF21, SF22, SF23, SF24, SF25 having weights of 1, 2, 4, 8, and 16, respectively, and the subfields of the first group. The field may represent 0 to 31 gradations. The subfields of the second group are weights that are 1 greater than the sum of the weights of the subfields SF21, SF22, SF23, SF24, SF25 of the first group, that is, the subfields SF26, SF27, SF28 having a weight of 32. , SF29, SF2 (10), SF2 (11), and SF2 (12), and the subfields of the second group include grayscales corresponding to multiples of 32 from 0 to 224 (= 32 × 7) grayscales. I can express it. For example, when erase discharge occurs in the ninth subfield SF29 after the write discharge occurs in the sixth subfield SF26, 96 gray scales (= 32 × 3) are represented, and write in the sixth subfield SF26 occurs. If the erase discharge does not occur in the remaining subfields SF27 to SF2 (12) after the discharge has occurred, 224 (= 32 x 7) gradations are represented.

Therefore, the combination of the subfields SF21 to SF2 (12) of the first group and the second group enables expression from 0 to 255 (= 224 + 31) gradations. Since it can be expressed accurately, it is possible to improve the expression of low gradation compared to the first embodiment.

Meanwhile, when the gray scale representation method of FIG. 6 is used to actually represent the intermediate gray scale in which the video is driven, one or more discharges occur in the subfields of the first group and up to two discharges occur in the subfields of the second group. Halftone can be expressed. In this case, the address power consumption is hardly reduced as compared with the case where the weight is represented by a combination of the subfields having respective weights in one field and the write discharge has occurred. For example, when expressing 107 gradations, when the gradation method of FIG. 6 is used, write discharge occurs in the first, second, and sixth subfields SF21, SF22, SF23, SF26, and the ninth subfield SF29. ), Erase discharge occurs, and 107 gradations are represented. On the other hand, when one field consists of eight subfields each having a weight of 1, 2, 4, 8, 16, 32, 64, and 128, and the weight is represented by a combination of subfields in which write discharge has occurred, 1, 2 In the subfields having weights of 4, 32, and 128, write discharge occurs, and 107 gray levels are represented. As described above, since the address discharge occurs five times in total in order to express 107 gradations, there is almost no difference in address power consumption.

In the gray scale representation method of FIG. 6, up to six write discharges and one erase discharge, that is, up to seven discharges, may occur in the address period. That is, a large number of discharges may occur in the address period, and thus power consumption in the address period may increase.

Hereinafter, a gray scale representation method for reducing power consumption in an address period will be described in detail with reference to FIG. 7.

FIG. 7 is a diagram illustrating a gradation representation method according to a third embodiment of the present invention using the driving method illustrated in FIG. 5.

As shown in FIG. 7, in the gradation representation method according to the third embodiment of the present invention, gradation is expressed by a combination of subfields of the first group and the second group, and the specific gradation abnormality is greater than the second group. The gray level is expressed by a combination of subfields. Gray scales that cannot be expressed as subfields of the second group among the gray scales above the specific gray scale are expressed by applying dithering. In this case, the gray level below the specific gray level is expressed only by the combination of the subfields of the first and second groups as described with reference to FIGS. 5 and 6, so that the low gray level expressing power may be increased. Since the gray level above a certain gray level is expressed only by the combination of subfields of the second group, the number of address discharges can be reduced to 2 or less, and even when gray level is expressed by dithering, a problem of low gray level expressive power may occur since it is an area of relay gray level or high gray level. I never do that.

In general, a plasma display panel is often used to express a moving image, and the moving image generally includes a plurality of intermediate gray level images. Therefore, in the third exemplary embodiment, gray levels are expressed by combining and dithering subfields of the second group with respect to the gray scales or more that occur frequently in a moving image. For example, in the case of expressing 0 to 255 gradations, in gradations of 85 or more gradations corresponding to (1/3) of the 255 gradations, the gradations may be expressed only by the combination of the second subfield group. However, in the third embodiment, since the multiples of 32 are expressed only by the combination of the second subfields, the gradations may be expressed by the combination and dithering of the subfields of the second group for 96 or more gradations.

That is, gray scales can be expressed by a combination of subfields of the second group for 96 or more gray levels, and gray scales can be expressed by a combination of the first group and the second group subfields for gray levels of 96 or less. In addition, gray scales that cannot be expressed in multiples of 32 among 96 gray scales, that is, 100 gray scales, may be represented by dithering. That is, when 128 grays are used for two pixels and 96 grays are used for the remaining 14 pixels in the 4x4 pixel area, 100 grays (= 96 x 14 + 128 x 2/16) can be expressed. As described above, since gray levels of 96 or more are expressed only by the subfields of the second group, address discharges of two or less times occur in total. Therefore, compared to the gray scale representation method of FIG. 6, the address power consumption can be reduced more than a half gray scale.

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 exemplary embodiment of the present invention, since the address period is formed between the sustain periods of each row group, the priming particles formed in the sustain period can be sufficiently utilized in the address period. You can do

In another embodiment of the present invention, a plurality of subfields are divided into a plurality of subfield groups in one field. The first subfield group includes a plurality of subfields having respective weights, and selects a light emitting cell by a selective writing method, and the second subfield group includes a plurality of subfields having the same weight and is leading in time. At least one subfield positioned at selects a light emitting cell by a selective writing method, and the remaining subfields select a non-light emitting cell from a light emitting cell by a selective erasing method. In this case, the gray level below the specific gray level is expressed by the sum of the weights of the subfields of the first and second subfield groups, and the gray level above the specific gray level is expressed by the sum of the weights of the subfields of the second subfield group. This is reduced.

Claims (12)

In a plasma display device including a plurality of row electrodes, a plurality of column electrodes, and a plurality of discharge cells defined by the row electrodes and the column electrodes, a driving method for expressing gray scales by dividing one field into a plurality of subfields To Dividing the plurality of row electrodes into a plurality of row groups, dividing the plurality of subfields into the plurality of subfield groups, In each subfield of the first subfield group including a plurality of subfields having respective weights, selecting a light emitting cell from the plurality of discharge cells and sustain-discharging the light emitting cell; In a first subfield of a second subfield group including a plurality of subfields having the same weight, light emitting cells are selected from discharge cells of a first row group among the plurality of row groups, and light emitting cells of the plurality of row groups Sustaining and discharging a discharge cell in a state; and In the second subfield of the second subfield group, a non-light emitting cell is selected from the light emitting cells of the first row group among the plurality of row groups, and the discharge cells of the light emitting cell states of the plurality of row groups are sustained and discharged. Steps, A method of driving a plasma display device, which expresses a gray level equal to or greater than a specific gray level only by the second subfield group. The method of claim 1, The gray level below the specific gray level is expressed by a combination of the first subfield group and the second subfield group. The method of claim 2, In each subfield of the first subfield group and the first subfield of the second subfield group, resetting the plurality of discharge cells to non-light emitting cells before selecting the light emitting cells; Method of driving the device. The method of claim 2, In the first subfield of the second subfield group, light emitting cells are selected from discharge cells of a second row group among the plurality of row groups, and the discharge cells of the light emitting cell states of the plurality of row groups are sustained and discharged. Step, and In the second subfield of the second subfield group, non-light emitting cells are selected from light emitting cells of a second row group among the plurality of row groups, and sustain discharge is performed in discharge cells of light emitting cell states of the plurality of row groups. And driving the plasma display device. The method of claim 4, wherein After the light emitting cells of the last row group of the plurality of row groups are sustained and discharged in the third subfield positioned last in the second subfield group in time, Setting the light emitting cells of the first row group among the plurality of row groups as non-light emitting cells, and then sustain-discharging the discharge cells in the light emitting cell state of the plurality of row groups; and And setting the light emitting cells of the second row group among the plurality of row groups as non-light emitting cells, and then sustain-discharging the discharge cells in the light emitting cell states of the plurality of row groups. The method according to any one of claims 1 to 5, And the specific gradation is 96 gradations. The method of claim 6, The sum of the weights of the respective subfields of the first subfield group is one less than the weight of each of the subfields of the second subfield group. A plasma display panel including a plurality of row electrodes for performing a display operation and a plurality of column electrodes formed in a direction crossing the row electrodes, wherein a plurality of discharge cells are formed by the plurality of row electrodes and the plurality of column electrodes , A control unit for dividing the plurality of row electrodes into a plurality of row groups and dividing the plurality of subfields into a plurality of subfield groups to control gradation; In each subfield of the first subfield group including a plurality of subfills having respective weights, light emitting cells are selected from the plurality of discharge cells during a first address period, and sustain discharge of the light emitting cells during a first sustain period. Let's In the first subfield of the second subfield group including the plurality of subfields having the same weight, the light emitting cells are discharged from the discharge cells of each row group during the second address period for each row group of the plurality of row groups. Selects and sustain discharges the discharge cells in the light emitting cell state of the plurality of row groups during a second sustain period positioned between two adjacent second address periods, In the second subfield of the second subfield group, a non-light emitting cell is selected from light emitting cells of each row group during a third address period for each row group of the plurality of row groups, and the two adjacent third A driving unit for sustaining and discharging discharge cells in the light emitting cell states of the plurality of row groups during a third sustaining period located between address periods, The control unit displays a gray level of a specific gray level or more only in the second subfield group. The method of claim 8, The control unit displays a gray level below the specific gray level as a combination of the first and second subfield groups. The method of claim 8, The driving unit, After the light emitting cells of the last row group of the plurality of row groups are sustained and discharged in the third subfield that is located last in the second subfield group in time, Setting the light emitting cells of each row group to non-light emitting cells during an erasing period for each row group of the plurality of row groups, and then emitting light of the plurality of row groups during a fourth sustaining period located in two adjacent erasing periods A plasma display device for sustain discharge of a discharge cell in a cell state. The method according to any one of claims 8 to 10, And the control unit sets the weight of the first subfield of the second subfield group to be greater than the sum of the weights of the respective subfields of the first subfield group. The method of claim 11, And the control unit dithers and displays a gray level which is not a multiple of a weight of the first subfield of the second subfield group among the grays equal to or greater than the specific gray level.

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