This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for PLASMA DISPLAY AND DRIVING METHOD THEREOF earlier filed in the Korean Intellectual Property Office on the 6 Oct. 2005 and there duly assigned Ser. No. 10-2005-0093815.
1. Technical Field
The present invention relates to a plasma display device and a driving method thereof.
2. Related Art
A plasma display device uses a plasma display panel (PDP) which uses plasma generated by gas discharge to display characters or images. The PDP includes a plurality of discharge cells arranged in a matrix pattern.
In a general plasma display device, a field (1 TV field) is divided into a plurality of subfields respective weights, and gray scales are expressed by a summation of weights of subfields at which a display operation is generated from among the subfields. Each subfield has an address period in which an address operation for selecting discharge cells to emit light and discharge cells to emit no light from among a plurality of discharge cells occurs, and a sustain period in which a sustain discharge occurs in the selected discharge cells to perform a display operation during a period corresponding to a weight of a subfield.
Such a plasma display device uses subfields having different weight values for expression of grayscales. In addition, a grayscale of a corresponding discharge cell is expressed by a total of the weight values of subfields in which the discharge cell emits light at the plurality of subfields of the discharge cell. When the subfields with weights in the format of a power of 2 are used, contour noise can occur when a discharge cell expresses the grayscales of 127 and 128 in two consecutive frames.
In addition, when address and sustain periods are temporally separated, the length of one subfield becomes longer because the respective subfields have additionally formed address periods for addressing all of the discharge cells other than the sustain period for a sustain discharge. As a result, the number of subfields available in one field is reduced since the subfield has a longer length.
The above information disclosed in this section is provided only to enhance an understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art in this country.
The present invention has been developed in an effort to provide a plasma display device and a driving method thereof having the advantages of reducing false contour and the length of a subfield.
An exemplary embodiment of the present invention provides a method for driving a plasma display device having a plurality of row electrodes and a plurality of column electrodes, and a plurality of discharge cells defined by the plurality of row and column electrodes, and one field is divided into a plurality of subfields. The driving method comprises the steps of: dividing the plurality of row electrodes into a first row group disposed in even-numbered rows and a second row group disposed in odd-numbered rows; dividing the first row group of row electrodes into a plurality of first sub-groups and dividing the second row group of row electrodes into a plurality of second sub-groups; at respective first subfields of a first group of subfields among the plurality of subfields, selecting non-light emitting cells among light emitting cells of one first sub-group among the plurality of first sub-groups and sustain-discharging light emitting cells of at least one of the plurality of second sub-groups during a first period respectively corresponding to at least one second sub-group; and at the respective first subfields, selecting the non-light emitting cells among the light emitting cells of one of the plurality of second sub-groups and sustain-discharging the light emitting cells of at least one of the plurality of first sub-groups during a second period respectively corresponding to the at least one first sub-group.
Another exemplary embodiment of the present invention provides a plasma display device comprising: a plasma display panel (PDP) having 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 cells formed at crossing parts of the plurality of row electrodes and the plurality of column electrodes; a controller for dividing one field into a plurality of subfields, for dividing the plurality of row electrodes into a first row group disposed in odd-numbered rows and a second row group disposed in even-numbered rows, for dividing the first row group of row electrodes into a plurality of first sub-groups, and for dividing the second row group of row electrodes into a plurality of second sub-groups; and a driver for driving the plurality of row electrodes and the plurality of column electrodes. At this point, the driver at respective consecutive pluralities of first subfields among the plurality of subfields selects non-light emitting cells among light emitting cells of the respective first sub-groups during a first period of the respective first sub-groups, sustain-discharges the light emitting cells of the plurality of second sub-groups, selects non-light emitting cells among light emitting cells of the respective second sub-groups during a third period of the respective second sub-groups, and sustain-discharges the light emitting cells of the plurality of first sub-groups, wherein the third period is provided between adjacent first periods.
Yet another exemplary embodiment of the present invention provides a method for driving a plasma display device having a plurality of first and second row electrodes and a plurality of column electrodes, and a plurality of discharge cells defined by the plurality of first and second row and column electrodes, one field being divided into a plurality of subfields. The driving method comprises the steps of: dividing the respective pluralities of first and second row electrodes into a first row group disposed in odd-numbered rows and a second row group disposed in even-numbered rows; dividing the first row group of first row electrodes into a plurality of first sub-groups; dividing the second row group of first row electrodes into a plurality of second sub-groups; at one or more first subfields among the plurality of subfields, selecting light emitting cells among discharge cells of the first row group and sustain discharging the selected light emitting cells of the first row group; at the first subfield, selecting light emitting cells among discharge cells of the second row group and sustain-discharging the selected light emitting cells of the second row group; at each of the plurality of second subfields among the plurality of subfields, selecting non-light emitting cells among light emitting cells of one of the plurality of first sub-groups and sustain-discharging light emitting cells of at least one of the plurality of second sub-groups during a first period respectively corresponding to at least one second sub-group; and at the respective second subfields, selecting the non-light emitting cells among the light emitting cells of the one of the plurality of second sub-groups and sustain-discharging the light emitting cells of at least one of the plurality of first sub-groups during a second period respectively corresponding to the at least one first sub-group.
A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
In the following detailed description, only preferred embodiments of the invention have been shown and described, simply by way of illustration of the best modes contemplated by the inventor(s) of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive. To clarify the present invention, parts which are not described in the specification are omitted, and parts for which similar descriptions are provided have the same reference numerals. In addition, throughout this specification and the claims which follow, unless explicitly described to the contrary, the word “comprise” or variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
In addition, wall charges mentioned in the following description mean charges formed and accumulated on a wall (e.g., a dielectric layer) close to an electrode of a discharge cell. A wall charge will be described as being “formed” or “accumulated” on the electrode, although the wall charges do not actually touch the electrodes. Furthermore, a wall voltage means a potential difference formed on the wall of the discharge cell by the wall charge.
A plasma display device according to an exemplary embodiment of the present invention will now be described with reference to
As shown in
The PDP 100 includes a plurality of address electrodes A1 to Am (hereinafter referred to as “A electrodes”) extending in a column direction, and a plurality of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn (hereinafter respectively referred to as “X electrodes” and “Y electrodes”) extending in a row direction by pairs. The X electrodes X1 to Xn are formed in correspondence to the Y electrodes Y1 to Yn, and a display operation is performed by the X and Y electrodes in the sustain period. The Y electrodes Y1 to Yn and X electrodes X1 to Xn are arranged perpendicular to the A electrodes A1 to Am. In this regard, a discharge space formed at an area where the A electrodes A1 to Am cross the X and Y electrodes X1 to Xn and Y1 to Yn, respectively, forms a discharge cell 12. The configuration of the PDP 100 shown in
The controller 200 outputs X, Y, and A electrode driving control signals after externally receiving an image signal. In addition, the controller 200 drives the plasma display device by dividing a frame into a plurality of subfields, and controls the plasma display device by dividing the plurality of row electrodes into first and second row groups and by dividing the row electrodes of the first and second row groups into a plurality of respective sub-groups.
The address electrode driver 300 receives the address electrode driving control signal from the controller 200, and applies a display data signal for selecting a discharge cell to be discharged to each address electrode A.
The scan electrode driver 400 receives the scan electrode driving control signal from the controller 200, and applies the driving voltage to the scan electrode Y.
The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200, and applies the driving voltage to the sustain electrode X.
A driving method of the plasma display device according to the exemplary embodiment of the present invention will now be described in more detail with reference to
As shown in
In addition, in the first row group G1, first to (2j−1)-th Y electrodes Y1, Y3, . . . , Y2j−1 are grouped into a first sub-group G, and (2j+1)-th to (4j−1)-th Y electrodes Y2j+1, Y2j+3, . . . , Y4j−1 are grouped into a second sub-group G12. In such a manner, (14j+1)-th to (n−1)-th(=(16j−1)-th) Y electrodes Y14j+1, Y14j+3, . . . , Y16j−1, are grouped into an eighth sub-group G8 (here, j is given as an integer between 1 and n/16). Likewise, in the second row group G2, second to 2j-th Y electrodes Y2, Y4, . . . , Y2j are grouped into a first sub-group G21, and (2j+2)-th to 4j-th Y electrodes Y2j+2, Y2j+4, . . . , Y4j are grouped into a second sub-group G22. In such a manner, (14j+2)-th to n-th(=16j-th) Y electrodesy Y14j+2, Y4j+4, . . . , Y16j are grouped into an eighth sub-group G28. Meanwhile, the Y electrodes spaced apart by a predetermined interval in the first and second row groups G1 and G2 may be grouped into one sub-group, and if necessary, the Y electrodes may be grouped in an irregular manner.
Referring to
There are a selective write method and a selective erase method used to select discharge cells to emit light and those to emit no light among the plurality of discharge cells. The selective write method selects discharge cells to emit light and forms a constant wall voltage. The selective erase method selects discharge cells to emit no light and erases the formed wall voltage. That is, the selective write method sets a discharge cell to a light-emitting cell state by address-discharging the same so as to form wall charges therein, and the selective erase method sets the light-emitting discharge cell to a non-light emitting cell state by address-discharging the same so as to erase the wall voltage formed therein. According to these methods, an address discharge for forming the wall voltage will be referred to as a “write discharge” and an address discharge for erasing the wall charge will be referred to as an “erase discharge”.
Referring to
Subsequently, at the first subfield SF1, the address periods EAl11, to EAL18 and EA121 to EAL28 and sustain periods S111, to SL18 and S121 to SL28 are sequentially performed for the respective first to eighth sub-groups G11 to G18 and G21 to G28 of the first and second row groups G1 and G2. At the respective subfields SF1 to SFL of the first row group G1, the address periods EA111 to EAL18 and sustain periods S111 to SL18 are subsequently performed from the first sub-group G11 to the eighth sub-group G18, and at the respective subfields SF1 to SFL of the second row group G2, the address periods EA128 to EAL21 and sustain periods S128 to SL21 are subsequently performed from the eighth sub-group G28to the first sub-group G21. That is, at the k-th subfield SFk of the first row group G1, address periods EAk1i of i-th sub-group G1i are performed, and then sustain periods Sk1i of the i-th sub-group G1i are performed (here, k is an integer in a range of 1 to L and i is an integer in a range of 1 to 8). Subsequently, address periods EAk1(i+1) and sustain periods Sk1(i+1) of (i+1)-th sub-group G1(i+1) are performed. At the k-th subfield SFk of the second row group G2, address periods EAk2(i+1) of the (i+1)-th sub-group G2(i+1) are performed and then sustain periods Sk2(i+1) of the (i+1)-th sub-group G2(i+1) are performed. Subsequently, address periods EAk2i and sustain periods Sk2i of the i-th sub-group G2i are performed.
In addition, at the k-th subfield SFk, the address periods EAk2(8−(i−1)) of the (8−(i−1))-th sub-group G2(8−(i−1)) of the second row group G2are performed while the sustain periods Sk1i of the i-th sub-group G1i of the first row group G1 are performed. At the k-th subfield SFk, the address periods EAk1(i+1) of the (i+1)-th sub-group G1(i+1) of the first row group G1 are performed while the sustain periods Sk2(8−(i−1)) of the (8−(i−1))-th sub-group G2(8−(i−1)) of the second row group G2are performed.
In
Next, the respective subfields SF1 to SFL of the first row group G1 will be described in detail. Since the address and sustain periods have substantially the same operations for the respective subfields SF1 to SFL, the operation for only the k-th subfield SFk will be described (here, k is given as an integer in the range of 1 to L).
In the k-th subfield SFk of the first row group G1, during the address period EAk11 of the first sub-group G11, the erase discharges are generated in the discharge cells to be set as the non-light emitting cells among the light emitting cells of the first sub-group G11, and accordingly, the wall charges are erased, and during the sustain period Sk11, other light-emitting cells of the first sub-group G11 are sustain-discharged. Subsequently, during the address period EAk12 of the second sub-group G21, the erase discharges are generated in the discharge cells to be set as the non-light emitting cells among the light emitting cells of the second sub-group G12, and accordingly, the wall charges are erased, and during the sustain period Sk12, other light emitting cells of the second sub-group G12 are sustain-discharged. In addition, the light emitting cells of the first sub-group G11 are sustain-discharged.
In such a manner, the address periods EAk13 to EAk18 and sustain periods Sk13 to Sk18 are performed in other sub-groups G13 to G18. At this point, during the sustain periods Sk1i of the i-th sub-group G1i, the light emitting cells of the i-th sub-group G1i, the first to (i−1)-th sub-groups G11 to G1(i−1), and the (i+1)-th to eighth sub-groups G1(i+1) to G18 are sustain-discharged. The light emitting cells of the first to (1−1)-th sub-groups G11 to G1(i−1) have not undergone an erase discharge during the respective address periods EAk11 to EAk1(i−1) of the k-th subfield SFk, and the light emitting cells of the (i+1)-th to eighth sub-groups G1(i+1) to G18 have not undergone an erase discharge during the respective address period EA(k−1)1(i+1) to EA(k−1)18 of the (k−1)-th subfield SF(k−1). In addition, the light emitting cells of the i-th sub-group G1i have undergone a sustain discharge until the sustain period SK(i−1) which is immediately before the address period EA31i of the i-th sub-group G1i of the (k+1)-th subfield (SF(k+1)). That is, the light emitting cells of the i-th sub-group G1i are sustain-discharged during the total of eight sustain periods.
As such, at all of the subfields SF1 to SFL, the address periods EA211 to EA218, . . . , and EAL11 to EAL18 and sustain periods S211 to S218, . . . , SL11 to SL18 are performed for the respective sub-groups G11 to G18. With the discharge cells operated in such a manner, the discharge cells set as the light emitting cells during the reset period R consecutively perform a sustain discharge until the discharge cells are set as the non-light emitting cells by the erase discharges at the respective subfields SF1 to SFL. When the discharge cells become non-light emitting cells as a result of the erase discharges, the discharge cells are not sustain-discharged after the corresponding subfields. At this point, the respective subfields SF1 to SFL have weight values corresponding to a sum of the lengths of the eight sustain periods of the respective subfields SF1 to SFL.
In addition, at the last subfield SFL of the first row group G1, respective first to seventh sustain periods SA112 to SA118 maybe additionallyperformed for the respective second to eighth sub-groups G12 to G18 such that the number of sustain discharges of the second to eighth sub-groups G12 to G18 are the same for each sub-group.
At the last subfield SFL, additional sustain periods SA12 to SA18 maybe formed in the respective second to eighth sub-group G12 to G18. In addition, in order not to generate a sustain discharge in the row group having undergone the eight sustain periods during the additional sustain periods SA12 to SA18, the erase periods ER11 to ER17 for erasing the wall discharges formed in the immediately previous sub-groups G11 to G17 are formed immediately before the additional sustain periods SA12 to SA18.
Meanwhile, the erase period ER18 for erasing the wall charges of the eighth sub-group G18 may be formed after the additional sustain period SA18 of the eighth sub-group G18. In addition, the erase period ER18 of the eighth sub-group G18 may not be formed because the reset period R is performed at the first subfield SF1 of the consecutive fields. In addition, the erase operation of such erase periods ER11 to ER18 may be sequentially performed for the respective row electrodes of the respective sub-groups as in the address period, and may be simultaneously performed for all of the row electrodes of the respective row groups.
In more detail, the wall charge formed in all of the discharge cells of the first sub-group G11 are erased during the erase period ER11 after the sustain period SL18 of the eighth sub-group G18 of the last subfield SFL of the first row group G1 is performed. Then, during the additional sustain period SA12, the light emitting cells of the second to eighth sub-groups G12 to G18 are sustain-discharged. Subsequently, during the erase period ER12, the wall charges formed in all discharge cells of the second sub-group G12 are erased, and then during the additional sustain period SA13, the light emitting cells of the third to eighth sub-groups G13 to G18 are sustain-discharged. In such a manner, the additional sustain period SAL18 is carried out. With such an operation, the number of sustain discharges are the same in the light emitting cells of the respective sub-groups G11 to G18.
Subsequently, referring to the respective subfields SF1 to SFL of the second row group G2, the respective subfields SF1 to SFL of the second row group G2 have substantially the same structure as the respective subfields SF1 to SFL of the first row group G1. However, as described above, at the respective subfields SF1 to SFL of the second row group G2, the address periods EA128 to EA121, . . . , EAL28 to EAL21 are subsequently performed in a sequence from the eighth sub-group G28 to the first sub-group G21, and also, the erase periods ER21 to ER28 of the last subfields SFL of the second row group G2 are subsequently performed in a sequence from the eighth sub-group G28 to the first sub-group G21.
If such a driving method of the plasma display device is expressed only by the subfields, it may be given as in
In such a manner, the sustain period may be performed for the row electrodes of the second row group G1 during the address period of the row electrodes of the first row group G2, and the sustain period may be performed for the row electrodes of the second row group G1 during the address period of the row electrodes of the first row group G2. That is, the length of the one subfield may be reduced because the address and sustain periods are not separated, and the sustain period may be performed during the address period.
Subsequently, a driving waveform used to the driving method of the plasma display device according to the first exemplary embodiment of the present invention is described in detail with reference to
In
As shown in
The sustain pulse having a high-level voltage (a voltage Vs in
Then, during the address period EAi12, the scan pulse of the voltage VSCL is sequentially applied to the plurality of Y electrodes of the second sub-group G12 while the reference voltage is applied to the X electrodes of the first row group G1, and the address pulse (not shown) having a positive voltage is applied to the A electrodes of the cells to be selected as the non-light emitting cells among the light emitting cells formed by the Y electrodes to which the scan pulse is applied.
In addition, the sustain pulse is applied in inverse phases to the plurality of X electrodes of the first row group G1 and the Y electrodes of the first and second sub-groups G11 and G12, respectively, during the sustain period Si12, and accordingly, the light emitting cells are sustain-discharged. In such a manner, the address periods EA113 to EA118 and the sustain periods S113 to S118 are performed for other sub-groups G13 to G18.
In addition, the address period EAi28 of the eighth sub-group G28 of the i-th subfield SFi is performed in the second row group G2, while the sustain period Si11 of the first sub-group G11 is performed in the i-th subfield SFi of the first row group G1. At the i-th subfield SFi of the second row group G2, a scan pulse of a voltage VscL is applied to the plurality of Y electrodes of the eighth sub-group G28, while a reference voltage is applied to the X electrodes of the second row group G2, and the address pulse (not shown) having a positive voltage is applied to the A electrodes of the cells to be selected as the non-light emitting cells from among the light emitting cells formed by the Y electrodes to which the scan pulse is applied during address period EAi28 of the eighth sub-group G28.
In addition, the sustain pulse is applied in inverse phases to the plurality of X electrodes of the second row group G2 and the Y electrodes of the seventh to eighth sub-groups G21 and G28 during the sustain period Si28, and accordingly, the light emitting cells are sustain-discharged. Furthermore, the address period EAi12 of the second sub-group G12 is performed at the i-th subfield SFi of the first row group G1 while the sustain period Si28 is performed at the i-th subfield SFi of the second row group G2. In such a manner, the address periods EAi27 to EAi21 and the sustain periods Sk27 to Sk21 are performed for other sub-groups G27 to G21.
The sustain pulse of an inverse phase is applied to the plurality of X electrodes of the second row group G2 and the Y electrodes of the first and second sub-groups G11 and G12 during the sustain period Sk28, and accordingly, the sustain discharge is generated in the light emitting cells. In such a manner, the address periods EAi13 to EAi18 and the sustain periods Sk13 to Sk18 are performed for other sub-groups G13 to G18.
As such, since the priming particles formed during the sustain period are sufficiently used during the address period in that the address periods are disposed between the sustain periods of the respective sub-groups, the width of the scan pulse become shorter so as to thereby increase the speed of the scan, and the sustain period may be operated during the address period so as to thereby reduce the length of the subfield.
In
As also shown in
As such, according to the first exemplary embodiment of the present invention, a false contour cannot be generated because the erase discharge is generated at the corresponding subfield of the plurality of subfields SF1 to SF19, so that the grayscale is expressed by the consecutive subfields until a point in time before the discharge cells of the light emitting cell state become non-light emitting cells. In addition, at most one discharge may be required to express any grayscale because the discharge cells set to the light emitting cell state during the reset period R consecutively perform the erase discharge until they are set to non-light emitting cells by the erase discharge at the respective subfields SF1 to SF19. Therefore, power consumption according to the erase discharge may be reduced. However, the performance of a low grayscale expression may be decreased in the case where the low grayscale is not expressed by the combination of the subfields, but it is expressed by dithering. This is because the human eye can more effectively recognize a grayscale difference of a low grayscale than a grayscale difference of a high grayscale.
A method for enhancing the performance of the low grayscale expression may be described with reference to
As shown in
Subsequently, a method for realizing weight values of subfields SF1 to SF6 of the first group will be described with reference to
In
As described above, when the first and second row groups G1 and G2, respectively, are divided into eight sub-groups G11 to G18 and G21 to G28, respectively, the weight values of the respective subfields SF1 to SFL correspond to the sum of the length of eight sustain periods at the respective subfields SF1 to SFL. For example, assuming that the weight value of the subfield SFk shown in
Therefore, the weight value 1 corresponds to ¼ of the length of the sustain period Sk11as shown in
Likewise, a weight value of 2 corresponds to half of the length of the sustain period Ski,. Accordingly, as shown in
When each of four sustain pulses are applied to the X and Y electrodes during the sustain period Sk11 and the voltage VscH−VscL is applied to the Y electrodes as the low level voltage of the sustain pulse during the next seven sustain periods Sk12 to Sk18, a weight value of 4 may be realized. Also, when each of four sustain pulses is applied to the X and Y electrodes during the sustain periods Sk11 and Sk12, and the voltage VscH−VscL is applied to the Y electrodes as the low level voltage of the sustain pulse during the sustain periods Sk12 to Sk18, a weight value of 8 may be realized.
Assuming that the subfield SFk shown in
It is but one example that the voltages VscH to VscL may be applied to the Y electrodes so that the sustain discharge is not generated between the electrodes X and Y in
According to the driving method of the first exemplary embodiment of the present invention, the reset discharge must become a strong discharge in order that all of the discharge cells be initialized during the reset period D immediately before the address period of the first subfield SF1 and the discharge cells are set into the light emitting cell state. In this case, there is a problem in that the contrast ratio is reduced because the black screen seems to be bright. In addition, it is difficult for the wall charges to be sufficiently generated such that all of the discharge cells are set as light emitting cells only during the reset period R. A method for stably generating an erase discharge which is capable of enhancing the contrast ratio will now be described in detail with reference to
As shown in
More specifically, at the reset period R′ of the first subfield SF1′, the discharge cells of the first and second row groups G1 and G2 are initialized and set to the non-light emitting cell state so that a write discharge may be generated in the address period WA11 and WA12. During l1 the address period WA11 the write discharge is generated in the discharge cells to be set as non-light emitting cells among the discharge cells of the first row group G1, and accordingly the wall charges are generated. Then, during the sustain period S11, the sustain discharge is generated in the light emitting cells of the first row group G1. Sequentially, the wall charges formed in the light emitting cells of the first row group G1 are erased. The light is emitted only during the sustain period S211 of the first sub-group G11 among the light emitting cells of the first row group G1.
Next, during the address period WA12, a write discharge is generated in the discharge cells to be set as light emitting cells among the discharge cells of the second row group G2, and accordingly the wall charges are generated. Then, during the sustain period S12, a sustain discharge is generated in the light emitting cells of the second row group G2, and accordingly the wall charges are erased.
As such, according to the second exemplary embodiment of the present invention, write discharges are sequentially performed for the plurality of row electrodes of the first and second row groups G1 and G2 during the address period WA11and WA12, and thus the light emitting cells are selected, and then the sustain periods S11 and S12 are performed to generate a sustain discharge. In such a manner, the wall charges may be sufficiently formed on the respective electrodes of the light emitting cells before the subfields SF2 to SFL having the address period of the selective erase method are performed.
Meanwhile, in order that the wall charges formed in the light emitting cells of the respective groups G1 and G2 after the sustain periods S11 and S12 of the respective groups G1 and G2 are erased at the first subfield SF1′, the pulse width of the last sustain pulse is set to be narrower than that of other sustain pulses during the sustain periods S11 and S12 of the respective groups G1 and G2 so that the wall charges are not formed. The wall charges formed by the sustain discharges may be erased using a waveform in which a voltage of the row electrodes is gradually changed immediately after the last sustain discharge pulse (e.g., a waveform changed in a ramp pattern).
In addition, in order that the light emitting cells be initialized into non-light emitting cells at the reset period R′ immediately before the address period WA11 or WA12 of the selective write method, a voltage may be gradually increased or gradually reduced at the reset period. That is, the voltage of the plurality of Y electrodes may be gradually increased and then gradually reduced during the reset period R′. Thus, the light emitting cells are initialized by erasing the wall charges on the discharge cells when a weak reset discharge is generated between the X and Y electrodes while the voltage of the plurality of Y electrodes is gradually increased and then gradually reduced. Accordingly, a strong discharge is not generated during the reset period R1, thereby enhancing the contrast ratio.
Likewise, for the second exemplary embodiment shown in
More specifically, as shown in
Next, during the address period WA12 of the first subfield SF1″, a write discharge is generated in the discharge cells to be set as light emitting cells among the discharge cells of the second row group G2, and accordingly the wall charges are generated. Then, during a partial period S121 of the sustain period S12, the sustain discharge is generated in the light emitting cells of the first and second row groups G1 and G2. In addition, during another partial period S122 of the sustain period S12, the sustain discharge is not generated in the light emitting cells of the first row group G1 but rather in the second row group G2while the sustain discharge is not generated in the light emitting cells of the first row group G1 but rather in the light emitting cells of the second row group G2. At this point, the same number of sustain discharges is set to be generated in the light emitting cells of the second row group G2during another partial period S122 of the sustain period S12 and in the light emitting cells of the first row group G1 during the sustain period S12.
When the weight value of first subfield SF1″ is not expressed by the two sustain periods S11 and S12, the additional sustain discharge may be generated in the light emitting cells of the first and second row groups G1 and G2, respectively, during the other partial period S122 of the sustain period S12.
In addition, according to the first to third exemplary embodiments of the present invention, at the last subfield SFL of one field, the erase periods ER112 to ER118 and ER122 to ER128 and the additional sustain periods SA12 to SA18 and SA22 to SA28 of the first and second row groups G1 and G2, respectively, may be formed or may be deleted. When the erase periods ER112 to ER118 and ER122 to ER128 and the additional sustain periods SA12 to SA18 and SA22 to SA28 are deleted, the addressing order of the respective sub-groups G11 to G18 and G21 to G28 among the respective groups G1 and G2over the plurality of fields are changed. Then, the same number of sustain discharges may be generated in the respective row groups.
Meanwhile, according to the fourth exemplary embodiment of the present invention, assuming 1024 row electrodes are driven under conditions that the selective erase method uses a width of the scan pulse of 0.7 μs, the eight sustain pulses are inputted during one sustain period, one sustain pulse (the pulse having high and low level voltages) is inputted for 5.6 μs, the length of the sustain period is given as 44.8 μs(=5.6 μs×8 rows), and the length of the address period is given as 44.8 μs(=0.7 μs×64 rows). Therefore, the length of the subfield is given as 716.8 μs(=44.8 μs×16). In addition, when the selective write method uses a width of a scan pulse of 1.3 μs, and a length of the reset period is given as 350 μs, the length of the address period is given as 665.6 μs(=1.3 μs×512 rows). In the case of a weight value of 1, assuming that one sustain pulse is applied during the sustain period S11, and 1.5 sustain pulses are applied during the sustain period S12, the length of the total sustain period S11+S12 is given as 14 μs(=5.6 μs×2.5). Therefore, the length of the subfield SF1 is given as 1695.2 μs(=350 μs+665.6 μs×2+l4 μs).
That is, in the case of the third exemplary embodiment, since time allocated to the subfield of the selective erase method is given as 14970.8 μs(=16666 to 1695.2) at one field, the 20(=14970.8/716.8) subfields of the selective erase method may be used at one field.
In addition, it is one example that the sustain pulse having the voltage Vs and 0V alternately in
As described above, according to the exemplary embodiments of the present invention, the plurality of row electrodes are divided into a first row group disposed in even-numbered rows and a second row group disposed in odd-numbered rows, and the respective groups are again divided into a plurality of sub-groups. In addition, the address periods are performed in the respective sub-groups of the respective first and second row groups at the respective subfields of the one field, and the sustain periods are performed between the address periods of respective sub-groups. The address periods are performed in the respective sub-groups of the second row group while the sustain periods are performed in the respective sub-groups of the first row group, and the sustain periods are performed in the respective sub-groups of the first row group while the address periods are performed in the respective sub-groups of the second row group. As such, since the priming particles formed during the sustain period are sufficiently used during the address period in that the address periods are 8 disposed between the sustain periods of the respective sub-groups, the width of the scan pulse becomes shorter so as to thereby increase the speed of the scan and the sustain period during the address period, thereby reducing the length of the subfield.
In addition, the address periods of the respective subfield are driven by the selective erase method, and the grayscales are expressed by the consecutive subfields until a point in time before the erase discharge is generated at the corresponding subfield, and thus a false contour cannot be generated. Furthermore, since only one erase discharge is generated to express any grayscales, power consumption is reduced.
When the first address period of the respective subfields is driven by the selective write method, sufficient wall charges may be formed, and accordingly an erase discharge may be stably generated at the next subfields driven by the selective erase method. A voltage which is gradually increased or gradually reduced is applied during the reset period of the subfield of the selective write method, and accordingly a strong discharge is not generated during the reset period, thereby enhancing the contrast ratio.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the above description is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
10-2005-0093815 | Oct 2005 | KR | national |