JP2006145976A - Method for driving plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for driving a plasma display panel that can increase the number of gradations of intermediate luminance level while suppressing a false contour. <P>SOLUTION: When a luminance level which is one gradation higher in luminance than a luminance level set corresponding to a light emission pattern wherein a discharge cell is set to an illumination mode in all subfields in a first subfield group consisting of the subfields to which luminance weights having values of "2" raised to exponential power is assigned, respectively, the discharge cell is set to the illumination mode in at least one subfield in a 2nd subfield group consisting of subfields to which luminance weights other than the values of "2" raised to the exponential power are assigned, respectively and at least one field in the first subfield group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for driving a plasma display panel.

  As a thin display device, an AC discharge type plasma display panel (hereinafter referred to as a PDP) that performs image display using a light emission phenomenon accompanying discharge is known. In the PDP, a plurality of discharge cells corresponding to pixels are arranged in a matrix. At this time, each discharge cell has only two states, a light emission state during discharge (maximum luminance level) and a light-out state during non-discharge (minimum luminance level). Therefore, gradation driving using the subfield method is performed on the PDP having such discharge cells in order to realize image display at an intermediate luminance level indicated by the input video signal. In gradation driving based on the subfield method, the display period of one field (or frame) in the input video signal is divided into N subfields, and light emission driving is performed on the discharge cells for each subfield. Each subfield is assigned a light emission period corresponding to the weight of the subfield.

For example, as shown in FIG. 1, when driving is performed by dividing a display period of one field into six subfields SF1 to SF6, each of the subfields SF1 to SF6 includes:
SF1: 1
SF2: 2
SF3: 4
SF4: 8
SF5: 16
SF6: 32
The light emission driving is performed by assigning the light emission period.

  At this time, for example, when displaying the luminance level “32”, the discharge cell is caused to emit light only by SF6 among the subfields SF1 to SF6. As a result, light emission is performed over a period of “32” within the display period of one field, so that a luminance level of “32” corresponding to the light emission period is visually recognized. Further, when displaying the luminance level “31”, the discharge cells are caused to emit light in the subfields SF1 to SF5 other than the subfield SF6. Thus, light emission is performed over a period of “31” (= 1 + 2 + 4 + 8 + 16) within the display period of one field, so that the luminance level of “31” corresponding to the light emission period is visually recognized.

  However, when the luminance level “32” is displayed as described above and when the luminance level “31” is displayed, the period during which the discharge cell is emitting and the period during which the discharge cell is extinguished are reversed. Therefore, there is a possibility that a false contour is visually recognized. That is, during the light emission period of the discharge cell in which the luminance level “32” is displayed, the discharge cell in which the luminance level “31” is displayed is in an extinguished state. On the other hand, during the light emission period of the discharge cell in which the luminance level “31” is displayed, the discharge cell in which the luminance level “32” is displayed is in an extinguished state. Therefore, when the area where the luminance level “32” is displayed and the area where the luminance level “31” is displayed are adjacent to each other in one screen, the process proceeds from SF6 to SF5 as shown in FIG. If the line of sight is moved between both regions at the switching timing, only the extinguished state (or the light emitting state) is continuously viewed. At this time, a black (or white) line is visually recognized as a false contour at the boundary between the area where the luminance level “32” is displayed and the area where the luminance level “31” is displayed. is there.

  Therefore, a gradation driving method for preventing such false contours has been proposed (see, for example, FIG. 3 of Patent Document 1).

  In such a gradation driving method, the display period of one field is divided into 14 subfields SF1 to SF14, and among the first gradation driving to the 15th gradation driving as shown in FIG. 2 according to the input video signal. Either one is executed. In FIG. 2, the light emission of the discharge cells is performed in the subfields marked with white circles, and the discharge cells are kept off in the subfields after the subfields marked with black circles. In other words, except for the first gradation drive for realizing black display, the discharge cell is always caused to emit light in the first subfield SF1, and thereafter, continuously in each of the number of subfields corresponding to the luminance level to be expressed. The discharge cell emits light. According to this gradation driving method, the discharge cells that are once turned off in one field period do not return to the lit state. Therefore, as shown in FIG. 1, since there is no combination of light emission patterns in which the light emission period and the light extinction period of the discharge cells in one field display period are reversed, the false contour is suppressed.

However, in such a gradation driving method, since the number of gradations that can be expressed for each discharge cell is only [number of subfields for dividing each field + 1], all intermediate luminances expressed by the input video signal are expressed. I can't.
JP 2000-231362 A

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a driving method of a plasma display panel that can increase the number of gray levels of an intermediate luminance level while suppressing false contours. It is.

  The driving method of the plasma display panel according to claim 1 includes N plasma display panels (N: an integer of 2 or more) per unit display period in which a plurality of discharge cells corresponding to each pixel are arranged in a matrix. A method of driving a plasma display in which gradation driving is performed in a subfield, wherein each of the subfields selectively discharges each of the discharge cells according to an input video signal, thereby setting each of the discharge cells in a lighting mode and An address step for setting one of the light-off modes, and a sustain step for repeatedly discharging only the discharge cells set for the light-on mode for the number of times corresponding to the luminance weight assigned to the subfield, And each of the subfields has a luminance weight of a value indicated by a power of 2 Any one of a first subfield group consisting of subfields assigned to each and a second subfield group consisting of subfields each assigned a luminance weight other than a value indicated by a power of 2 A luminance that is higher by one gradation than a luminance level that corresponds to the light emission pattern in which the discharge cells are set to the lighting mode in all subfields in the first subfield group. When expressing a level, the discharge cells are set to the lighting mode in at least one subfield in the second subfield group and in at least one subfield in the first subfield group.

  Set in accordance with the light emission pattern in which the discharge cells are set in the lighting mode in all subfields in the first subfield group consisting of subfields each assigned with a luminance weight of a value indicated by a power of 2 In the case of expressing a luminance level that is one gradation higher than the specified luminance level, a second subfield consisting of subfields to which luminance weights other than values indicated by powers of 2 are respectively assigned. The discharge cells are set to the lighting mode in at least one subfield in the group and in at least one subfield in the first subfield group.

  FIG. 3 is a diagram showing a schematic configuration of a plasma display device that drives a plasma display panel as a display panel to emit light based on the driving method according to the present invention.

  Such a plasma display device includes a panel drive unit including an address driver 20, a Y electrode driver 30, an X electrode driver 40, and a drive control circuit 50, and a PDP 10 as a plasma display panel.

The front transparent substrate carrying a PDP10 of the display surface (not shown), the row electrodes X ₁ to X _n and row electrodes Y ₁ to Y _n that extends laterally of each screen is formed. In addition, column electrodes D _{1 to} D _{m each} extending in the vertical direction of the screen are formed on the back substrate (not shown) of the PDP 10. The row electrodes X _{1 to} X _n and Y _{1 to} Y _n are alternately arranged on the front transparent substrate in the X and Y directions. Each pair of row electrodes (X, Y) adjacent to each other displays each display on the PDP 10. Make up line. A discharge space filled with a discharge gas is formed between the front transparent substrate and the back substrate, and a discharge cell (pixel) is provided at each intersection of the row electrode pair and the column electrode including the discharge space. Pixel cell) is formed.

  The drive control circuit 50 converts the input video signal into pixel data for each pixel, and generates pixel drive data indicating a mode (lighting mode, extinguishing mode) for setting each discharge cell based on the pixel data. , And supplied to the address driver 20. If the input video signal is subjected to gamma correction, the drive control circuit 50 performs reverse gamma correction on the input video signal to cancel the gamma correction, and then performs the pixel data conversion process as described above. Execute.

  Further, the drive control circuit 50 generates various timing signals to drive the PDP 10 in gray scale according to the light emission drive sequence based on the subfield method as shown in FIG. 4 and supplies the timing signals to the Y electrode driver 30 and the X electrode driver 40, respectively. Each of the address driver 20, the Y electrode driver 30, and the X electrode driver 40 applies various drive pulses to the column electrode D and the row electrodes X and Y of the PDP 10 according to the timing signal supplied from the drive control circuit 50.

  That is, the panel drive unit including the address driver 20, the Y electrode driver 30, the X electrode driver 40, and the drive control circuit 50 emits light as shown in FIG. 4 for each unit display period (one frame or one frame display period). Gradation driving for the PDP 10 is performed in seven subfields SF1 to SF7 based on the sequence.

  The panel driving unit executes the reset process Rc, the address process Wc, and the sustain process Ic in each of the subfields SF1 to SF7.

  In the reset process Rc, the panel driver discharges all discharge cells (hereinafter referred to as reset discharge), thereby initializing wall charges remaining in all the discharge cells to a predetermined amount or less.

  In the address process Wc, when the pixel drive data indicates a lighting mode, the panel drive unit selectively causes discharge (hereinafter referred to as address discharge) to discharge cells corresponding to the pixel drive data. At this time, a predetermined amount of wall charges are formed in the discharge cell in which the address discharge is generated, and the discharge cell is set to the lighting mode. The discharge cells in which no address discharge has occurred are set to the state immediately before that, that is, the extinguishing mode in which the amount of wall charges is a predetermined amount or less.

  In the sustain process Ic, the panel driver repeatedly discharges only the discharge cells set in the lighting mode for a period (or number of times) corresponding to the luminance weighting of the subfield (hereinafter referred to as a sustain discharge). The light emission state associated with the sustain discharge is maintained.

  In addition, as shown in FIG. 4, the following luminance weighting is given to each of the subfields SF1 to SF7.

SF1: 16
SF2: 46
SF3: 29
SF4: 8
SF5: 4
SF6: 2
SF7: 1
5 to 7 are based on the light emission drive sequence shown in FIG. 4, and the panel drive unit within the unit display period (one field or one frame display period) when driving the PDP 10 according to the input video signal. It is a figure which shows the light emission drive pattern.

  5 to 7, the discharge cell is set to the lighting mode in the subfield SF marked with a white circle. That is, in the sustain process Ic of the subfield, the discharge cell repeatedly sustains for a period (number of times) corresponding to the luminance weight assigned as described above, and the light emission state associated with the discharge is maintained. At this time, an intermediate luminance level corresponding to the total period (total number) of sustain discharges generated in the unit display period is visually recognized. That is, various luminance levels within the range from the lowest to the highest luminance level indicated by the input video signal can be expressed by 107 gradations by 107 light emission patterns as shown in FIGS.

Here, as shown in FIG. 4, a relatively small luminance weight is assigned to the subfield group including SF1 and SF4 to SF7 among the subfields SF1 to SF7. That is, the sub-field SF7 has the first smallest luminance weight “1”, SF6 has the second smallest luminance weight “2”, SF5 has the third smallest luminance weight “4”, and SF4. Is assigned the fourth smallest luminance weight “8”, and SF1 is assigned the fifth smallest luminance weight “16”. That is, luminance weights indicated by powers of 2 such as 2 ^(K-1) (K: the order of decreasing luminance weight) are assigned to SF1 and SF4 to SF7. Depending on the combination of the lighting and extinguishing states of each of the subfields (hereinafter referred to as power-of-two subfields) to which luminance weights indicated by powers of 2 such as the subfields SF1 and SF4 to SF7 are assigned, "0" Luminance components for 32 gradations from "to" 31 "are expressed. At this time, when the luminance level “31” is expressed, the discharge cells are set to the lighting mode in each of the subfields SF1 and SF4 to SF7 as described above, as indicated by the thick frame in FIG.

On the other hand, when expressing a luminance higher than the luminance level “31”, the subfield SF3 to which the sixth smallest luminance weight is assigned is also used. In this subfield SF3, the fifth smallest luminance weight “16”, the fourth smallest luminance weight “8”, and the third smallest luminance weight “4” are added. A luminance weight of “29” obtained by adding “1” to the result is assigned. That is, the power of 2 is assigned to the subfield SF3 as the sixth smallest luminance weight, that is, “29” smaller than “32” indicated by 2 ^(6-1) . Therefore, when expressing the luminance level “32” which is one level higher than the luminance level “31”, SF6 and SF7 are respectively shown in addition to the subfield SF3 as shown by the thick line frame in FIG. The lighting mode will be set. As a result, when the luminance level “31” is expressed and the case where “32” is expressed are compared, in each of the subfields SF1 and SF3 to SF5, the on / off state is inverted. However, regarding the subfields SF6 and SF7, the inversion of the lighting state does not occur between the case where the luminance level “31” is expressed and the case where “32” is expressed. Therefore, the false contour can be suppressed in all of the subfields SF1 and SF3 to SF7 as compared with the case where the turn-on and turn-off states are reversed.

  Each of the subfields SF1 and SF4 to SF7 plus SF3 represents a luminance level from “0” to “60” as shown in FIGS. At this time, when the luminance level “60” is expressed, the discharge cells are set to the lighting mode in each of the subfields SF1 and SF3 to SF7 as described above, as indicated by the bold frame in FIG.

Furthermore, when expressing a luminance higher than the luminance level “60”, the subfield SF2 to which the seventh smallest luminance weight is assigned is also used. This subfield SF2 is obtained by adding “1” to the result of adding the sixth smallest luminance weight “29” and the fifth smallest luminance weight “16” as described above. A luminance weight of “46” is assigned. That is, in the subfield SF2, the power weight of 2, that is, “46” smaller than “64” indicated by 2 ^(6-1) is assigned as the seventh smallest luminance weight. . Therefore, in order to express the luminance level “61” that is one level higher than the luminance level “60”, SF4 to SF7 are respectively displayed in addition to the subfield SF2, as indicated by the thick line frame in FIG. The lighting mode will be set. At this time, when the luminance level “60” is expressed with the case where “61” is expressed, the inversion of the on / off state occurs in each of the subfields SF1 to SF3, but the other subfields SF4 to SF4 are generated. With respect to SF7, the lighting state is not reversed. Therefore, it is possible to suppress the false contour as compared with the case where all the subfields SF1 to SF7 are turned on and off.

  In the light emission drive sequence shown in FIG. 4, SF1 to which the largest luminance weight “16” is assigned among the subfields to which relatively small luminance weights are assigned, and the second largest luminance. SF3 to which a relatively large luminance weight “29” is assigned is arranged between SF4 to which a weight is assigned. Further, after such SF4, SF5 to which the third smallest luminance weight is assigned, SF6 to which the second smallest luminance weight is assigned, and the smallest luminance weight are assigned. SF7 is sequentially arranged. According to this arrangement, the light emission center of gravity based on the light emission pattern corresponding to the luminance level “31” and the light emission center of gravity based on the light emission pattern corresponding to the luminance level “32” as shown by the bold frame in FIG. Therefore, the false contour is reduced as compared to the case where the respective light emission centers of gravity are dispersed within the unit display period.

  Furthermore, in the light emission drive sequence shown in FIG. 4, SF1 to which the largest luminance weight “16” is assigned among the subfields to which a relatively small luminance weight is assigned, and the luminance weight “29” as described above. SF2 to which the maximum luminance weight “46” is assigned is disposed between SF3 to which “is assigned”. According to this arrangement, the light emission center of gravity based on the light emission pattern corresponding to the luminance level “60” and the light emission center of gravity based on the light emission pattern corresponding to the luminance level “61” as shown in the thick line frame in FIG. Therefore, the false contour is reduced as compared with the case where the respective light emission centers of gravity are dispersed within the unit display period.

As described above, in the driving shown in FIGS. 4 to 7, the luminance weight indicated by the power of 2 is assigned to each of the subfields belonging to the first subfield group (SF1 and SF4 to SF7). A luminance weight other than the value indicated by the power of 2 is assigned to each of the subfields belonging to the two subfield groups (SF2 and SF3). The subfield SF3 belonging to the second subfield group is larger than the largest luminance weight “16” among the luminance weights assigned to SF1 and SF4 to SF7 belonging to the first subfield group. The luminance weight “29” is assigned. At this time, the luminance weight “16” is the fifth power of 2 which is the fifth smallest luminance luminance assigned to each of the subfields, that is, a value represented by 2 ^(5-1) . However, the luminance weight “29” is smaller than the sixth power of 2, that is, the value “32” indicated by 2 ^(6-1) . Therefore, in the case where all of the subfields SF1 and SF4 to SF7 have a luminance level that is higher by one level than the luminance level “31”, “60”, or “77” at which the discharge cells are set to the lighting mode, the SF2 Alternatively, together with SF3, the discharge cells are set to the lighting mode in at least one subfield among SF1 and SF4 to SF7.

  Therefore, according to such driving, even when adjacent discharge cells are driven to emit light at a luminance level different from each other by only one level, in the at least one subfield within the unit display period, the adjacent discharge cells are turned on and off. Since the turn-off state is not reversed, the generation of false contours can be suppressed. That is, according to the above drive, the number of gradations is increased more than the number of gradations (N + 1) obtained by adding “1” to the total number of subfields N in the unit display period while suppressing the occurrence of false contours. Display with improved image quality is possible.

  In the embodiment shown in FIGS. 4 to 7, the driving method in the case where the image based on the input video signal is represented by 107 gradations has been described. However, the number of gradations is not limited to 107.

  FIG. 8 is a diagram illustrating an example of a light emission drive sequence employed when an image based on an input video signal is expressed with 256 gradations.

  The panel drive unit including the address driver 20, the Y electrode driver 30, the X electrode driver 40, and the drive control circuit 50 is based on the light emission drive sequence shown in FIG. 8 for each unit display period (one frame or one frame display period). Gradation driving for the PDP 10 is performed in 11 subfields SF1 to SF11. The panel driving unit executes the address process Wc and the sustain process Ic in each of the subfields SF1 to SF11.

  In the address process Wc of each of the subfields SF1 to SF11, the panel drive unit causes the address discharge to occur only in the discharge cells corresponding to the pixel drive data only when the pixel drive data indicates the lighting mode. At this time, a predetermined amount of wall charges are formed in the discharge cell in which the address discharge is generated, and the discharge cell is set to the lighting mode. Note that the discharge cells in which no address discharge has been generated maintain the current state (lighting mode or extinguishing mode).

  In the sustain process Ic of each of the subfields SF1 to SF11, the panel driving unit repeatedly causes only the discharge cells set in the lighting mode to sustain discharge for a period (or number of times) corresponding to the luminance weighting of the subfield. The light emission state accompanying discharge is maintained.

  In addition, as shown in FIG. 8, the following luminance weighting is given to each of the subfields SF1 to SF11.

SF1: 16
SF2: 46
SF3: 46
SF4: 46
SF5: 29
SF6: 28
SF7: 29
SF8: 8
SF9: 4
SF10: 2
SF11: 1
That is, a subfield SF1 having a luminance weight of “16” is arranged at the head in the unit display period. Subfield group SG1 is arranged following such subfield SF1. In the subfield group SG1, subfields SF2, SF3, and SF4 to which the maximum luminance weight “46” is assigned are sequentially arranged. Subfield group SG2 is arranged following such subfield group SG1. In subfield group SG2, SF5 to which the second largest luminance weight “29” is assigned, SF6 to which luminance weight “28” that is smaller by “1” than that is assigned, and luminance weight “29” are assigned. Are sequentially arranged. Subsequent to the subfield group SG2, SF8 to which the fourth smallest luminance weight “8” is assigned, SF9 to which the third smallest luminance weight “4” is assigned, and second The SF 10 to which the lowest luminance weight “2” is assigned and the SF 11 to which the lowest luminance weight “1” is assigned are sequentially arranged.

  Prior to the address process Wc in the first subfield SF1, the first subfield SF2 in the subfield group SG1, the first subfield SF5 in the subfield group SG2, and the subfields SF8 to SF11, The reset process Rc is executed. In the reset process Rc, the panel driving unit causes reset discharges to occur simultaneously for all the discharge cells of the PDP 10 to initialize the amount of wall charges remaining in all the discharge cells to a predetermined amount or less. With this reset discharge, all discharge cells are forcibly set to the extinguishing mode.

  9 to 16 are based on the light emission drive sequence shown in FIG. 8, and the panel drive unit within the unit display period (one field or one frame display period) when driving the PDP 10 according to the input video signal. It is a figure which shows the light emission drive pattern.

  9 to 16, in the subfield SF marked with white circles, the discharge cells are set to the lighting mode. That is, in the sustain process Ic of this subfield, the discharge cells repeat discharge light emission over a period (number of times) corresponding to the luminance weight assigned as described above. At this time, an intermediate luminance level corresponding to the sum of the light emission periods within the unit display period by the subfields SF1 to SF11 is visually recognized.

  In the light emission drive sequence shown in FIG. 8, the reset process Rc is provided only in the first subfield SF2 in the subfield group SG1. Further, in the subfield group SG2, the reset process Rc is provided only in the first subfield SF5. Therefore, it is possible to reduce power consumption and improve contrast as compared with the case where the reset process Rc is provided in all subfields. At this time, in the subfield group SG1 (or SG2), only the subfield SF2 (or SF5) can be used to change the discharge cell from the lighting mode to the extinguishing mode. Therefore, once the discharge cell is set to the lighting mode in the address process Wc of any one of the subfields SF2 to SF4 (or SF5 to SF7), thereafter, in the SG1 (or SG2). The lighting mode is maintained up to the last subfield SF4 (or SF7), and sustain discharge light emission is continuously performed in each subfield.

Therefore, in the subfield group SG1, as shown in FIGS.
Lights only with SF4 Lights with each of SF3 and SF4 Lights with each of SF2 to SF4 Four gradations of “46”, “92”, “138”, and “0” by four types of light emission patterns such as turning off all of SF2 to SF4 The luminance component of the minute is expressed.

In the subfield group SG2,
Lights only with SF7 Lights with each of SF6 and SF7 Lights with each of SF5 to SF7 Four gradations of “29”, “57”, “86”, “0” by four types of light emission patterns such as all of SF5 to SF7 are turned off The luminance component of the minute is expressed.

On the other hand, each of the subfields SF1 and SF8 to SF11 having a small luminance weight is provided with a reset process Rc, and the luminance of 2 ^{(K−1) with} respect to the Kth subfield having the smallest luminance weight. Each weight is assigned. That is, 2 ^(1-1) = "1" for the subfield SF11 with the smallest luminance weight, 2 ^(2-1) = "2" for the second subfield SF11 with the smallest luminance weight, and the third 2 ^(3-1) = “4” for SF 9 with a smaller luminance weight, 2 ^(4-1) = “8” for SF 8 with the fourth smallest luminance weight, and fifth with a luminance weight. A luminance weight of 2 ^(5-1) = “16” is assigned to small SF1. Therefore, the 32nd floor from “0” to “31” depends on the combination of the lighting state and the unlighting state by each of the subfields to which the luminance weights indicated by powers of 2 such as the subfields SF1, SF8 to SF11 are assigned. The luminance component of the adjustment is expressed.

  Accordingly, the combination of the light emission pattern for 4 gradations by the subfield groups SG1 and SG2 as described above and the light emission pattern for 32 gradations by the subfields SF1 and SF8 to SF11 as shown in FIG. 9 to FIG. 256 light emission drive patterns are obtained. As a result, various brightness levels within the range from the minimum brightness level to the maximum brightness level indicated by the input video signal can be expressed with 256 gradations.

  Here, in the driving shown in FIGS. 8 to 16 as well, as in the driving shown in FIGS. 4 to 7, the first subfields SF1 and SF8 to SF11 to which relatively small luminance weights are assigned. A luminance weight indicated by a power of 2 is assigned to the subfield group. Further, a luminance weight having a value other than a value indicated by a power of 2 is assigned to each subfield belonging to the second subfield group such as the subfield groups SG1 and SG2. At this time, in the case where the luminance level of the discharge cells is set to the lighting mode in all of the subfields SF1 and SF8 to SF11, the luminance level is expressed by one level higher than the luminance level “31”, “88”, or “134”. Together with SG1 or SG2, the discharge cells are set to the lighting mode in at least one subfield of SF1 and SF8 to SF11. Therefore, according to such driving, even when adjacent discharge cells are driven to emit light at a luminance level different from each other by only one level, in the at least one subfield within the unit display period, the adjacent discharge cells are turned on and off. Since the turn-off state is not reversed, the generation of false contours can be suppressed. That is, according to the above drive, the number of gradations is increased more than the number of gradations (N + 1) obtained by adding “1” to the total number of subfields N in the unit display period while suppressing the occurrence of false contours. Display with improved image quality is possible.

  Further, in the light emission drive sequence shown in FIG. 8, the largest among the subfields belonging to the first subfield group (SF1 and SF8 to SF11) to which the luminance weight indicated by a power of 2 is assigned. A relatively large luminance weight “29” or “28” is allocated between SF1 to which the luminance weight “16” is allocated and SF8 to which the second largest luminance weight is allocated. Subfield group SG2 is arranged. Further, a subfield group SG1 to which the largest luminance weight “46” is assigned is disposed between these SF1 and SF8. According to this arrangement, for example, the light emission center of gravity based on the light emission pattern corresponding to the luminance level “31” as shown in FIG. 9 and the light emission center of gravity based on the light emission pattern corresponding to the luminance level “32” as shown in FIG. Since it is near the center in the unit display period, the false contour is reduced as compared with the case where the respective light emission centers of gravity are dispersed in the unit display period.

  In the above embodiment, when the input video signal is subjected to gamma correction, the drive control circuit 50 performs the inverse gamma correction processing on the input video signal and then performs the pixel data conversion processing as described above. However, the inverse gamma correction processing may be incorporated into the gradation driving operation.

  FIG. 17 is a diagram showing an example of a light emission drive sequence that is employed when an image based on an input video signal is expressed with 115 gradations, including such inverse gamma correction processing.

  The panel drive unit including the Y electrode driver 30, the X electrode driver 40, and the drive control circuit 50 performs the address process Wc and the sustain process Ic in each of the 11 subfields SF1 to SF11 based on the light emission drive sequence shown in FIG. Execute.

  In the address process Wc of each of the subfields SF1 to SF11, the panel drive unit causes the address discharge to occur only in the discharge cells corresponding to the pixel drive data only when the pixel drive data indicates the lighting mode. At this time, a predetermined amount of wall charges are formed in the discharge cell in which the address discharge is generated, and the discharge cell is set to the lighting mode. Note that the discharge cells in which no address discharge has been generated maintain the current state (lighting mode or extinguishing mode).

  In the sustain process Ic of each of the subfields SF1 to SF11, the panel driving unit repeatedly causes only the discharge cells set in the lighting mode to sustain discharge for a period (or number of times) corresponding to the luminance weighting of the subfield. The light emission state accompanying discharge is maintained.

  As shown in FIG. 17, the subfields SF1 to SF11 are given the following luminance weighting.

SF1: 16
SF2: 46
SF3: 46
SF4: 46
SF5: 2
SF6: 29
SF7: 28
SF8: 29
SF9: 1
SF10: 8
SF11: 4
That is, a subfield SF1 having a luminance weight of “16” is arranged at the head in the unit display period. Subfield group SG1 is arranged following such subfield SF1. In the subfield group SG1, subfields SF2, SF3, SF4 to which the maximum luminance weight “46” is assigned and SF5 to which the second smallest luminance weight “2” is assigned are sequentially arranged. ing. Subfield group SG2 is arranged following such subfield group SG1. In subfield group SG2, SF5 to which the second largest luminance weight “29” is assigned, SF6 to which luminance weight “28” that is smaller by “1” than that is assigned, and luminance weight “29” are assigned. And SF1 to which the smallest luminance weight “1” is assigned are sequentially arranged. Subsequent to the subfield group SG2, SF10 to which the fourth smallest luminance weight “8” is assigned and SF11 to which the third smallest luminance weight “4” is assigned are arranged. ing.

  Prior to the address process Wc in the first subfield SF1, the first subfield SF2 in the subfield group SG1, the first subfield SF6 in the subfield group SG2, and the subfields SF10 and SF11, respectively. The reset process Rc is executed. In the reset process Rc, the panel driving unit causes reset discharges to occur simultaneously for all the discharge cells of the PDP 10 to initialize the amount of wall charges remaining in all the discharge cells to a predetermined amount or less. With this reset discharge, all discharge cells are forcibly set to the extinguishing mode.

  18 to 21 are based on the light emission drive sequence shown in FIG. 17, and the panel drive unit within the unit display period (one field or one frame display period) when driving the PDP 10 according to the input video signal. It is a figure which shows the light emission drive pattern.

  In FIG. 18 to FIG. 21, in the subfield SF marked with white circles, the discharge cells are set to the lighting mode. That is, in the sustain process Ic of this subfield, the discharge cells repeat discharge light emission over a period (number of times) corresponding to the luminance weight assigned as described above. At this time, an intermediate luminance level corresponding to the sum of the light emission periods within the unit display period by the subfields SF1 to SF11 is visually recognized.

  According to the light emission drive patterns shown in FIGS. 18 to 21, only the subfield SF2 (or SF6) has an opportunity to change the discharge cell from the lighting mode to the extinguishing mode in the subfield group SG1 (or SG2). It becomes. Therefore, once the discharge cell is set to the lighting mode in the address process Wc of any one of the subfields SF2 to SF5 (or SF6 to SF9), thereafter, in the SG1 (or SG2) The lighting mode is maintained up to the last subfield SF5 (or SF9), and sustain discharge light emission is continuously performed in each subfield.

Therefore, in the subfield group SG1, as shown in FIGS.
Lights only with SF5 Lights with each of SF4 and SF5 Lights with each of SF3 to SF5 Lights with each of SF2 to SF5 Each of SF2 to SF5 is turned off according to five types of light emission patterns “2”, “48”, “94”, “ The luminance components for five gradations of “140” and “0” are expressed.

In the subfield group SG2,
Lights only with SF9 Lights with each of SF8 and SF9 Lights with each of SF7 to SF9 Lights with each of SF6 to SF9 Each of SF6 to SF9 is turned off according to five types of light emission patterns “1”, “30”, “58”, “ The luminance components for five gradations of “87” and “0” are expressed.

  Further, “0”, “4”, “8”, “12” are obtained by eight kinds of light emission patterns of SF1, SF10, and SF11 which are relatively small and assigned luminance weights indicated by powers of 2. , “16”, “20”, “24”, “28” luminance components for 8 gradations are expressed.

  Accordingly, various intermediate luminance levels are expressed by combinations of light emission patterns by the subfield groups SG1, SG2, SF1, SF10, and SF11.

  Here, in the driving shown in FIGS. 17 to 21, in consideration of inverse gamma correction, the luminance difference between adjacent gradations is increased as the luminance level to be expressed increases. For example, as shown in FIG. 18, in the case of expressing low luminance from luminance levels “0” to “32”, the luminance difference between adjacent gradations is “1”, but from luminance level “32”. In the case of expressing high luminance, the value is “2” as shown in FIG. Furthermore, when expressing a luminance higher than the luminance level “118”, the luminance difference between adjacent gradations is set to “4” as shown in FIG. Therefore, according to this driving, various luminance levels within the range of the minimum luminance level to the maximum luminance level indicated by the input video signal, that is, the luminance levels “0” to “255” are shown in FIGS. Thus, it is possible to express with 115 gradations.

  In the drive shown in FIGS. 17 to 21 as well as the drive shown in FIGS. 4 to 7 or FIGS. 8 to 16, the subfields SF1, SF5, SF9, which belong to the first subfield group. A luminance weight indicated by a power of 2 is assigned to SF11. Furthermore, luminance weights having values other than those indicated by powers of 2 are assigned to subfields SF2 to SF4 and SF6 to SF8 belonging to the second subfield group. At this time, the luminance levels “31”, “88”, or “134” at which the discharge cells are set to the lighting mode in all of SF1, SF5, and SF9 to SF11 belonging to the first subfield group are higher by one level. In the case of representing luminance, as shown in FIGS. 18 to 21, the discharge cells remain in the lighting mode in at least one subfield among SF1, SF5, and SF9 to SF11. Therefore, according to such driving, even when adjacent discharge cells are driven to emit light at a luminance level different from each other by only one level, in the at least one subfield within the unit display period, the adjacent discharge cells are turned on and off. Since the turn-off state is not reversed, the generation of false contours can be suppressed. In the light emission driving sequence shown in FIG. 17, SF1 to which the largest luminance weight “16” is assigned among the subfields to which the luminance weight indicated by a power of 2 is assigned, and the second A subfield group to which the largest luminance weights “46” and “29” are assigned is arranged between the SF 10 to which the highest luminance weight is assigned. With this arrangement, for example, the light emission center of gravity based on the light emission pattern corresponding to the luminance level “31” and the light emission center of gravity based on the light emission pattern corresponding to the luminance level “32” are both near the center in the unit display period. The false contour is reduced as compared with the case where the respective light emission centers of gravity are dispersed within the unit display period. Further, in the light emission drive sequence shown in FIG. 17, the reset process Rc that can change the discharge cell from the lighting mode to the extinguishing mode is provided only in the five subfields of the subfields SF1, SF2, SF6, SF10, and SF11. I am doing so. Therefore, the number of reset steps Rc to be executed within a unit time is reduced as compared with the case where driving based on the light emission driving sequence shown in FIG. 4 or FIG. 8 is performed, thereby reducing power consumption and improving contrast. Is possible.

  Further, in the light emission drive sequence shown in FIG. 8 or FIG. 17, the drive for each unit display period is performed by 11 subfields, but the number of subfields is not limited to 11.

  For example, instead of the light emission drive sequence shown in FIG. 8, a light emission drive sequence as shown in FIG. 22 in which gradation drive is performed in 12 subfields may be adopted.

  The following luminance weights are assigned to each of the 12 subfields SF1 to SF12 shown in FIG.

SF1: 32
SF2: 86
SF3: 86
SF4: 86
SF5: 85
SF6: 52
SF7: 53
SF8: 16
SF9: 8
SF10: 4
SF11: 2
SF12: 1
That is, the subfield SF1 to which the sixth smallest luminance weight “32” is assigned is arranged at the head in the unit display period. Subfield group in which SF2, SF3, SF4 to which the maximum luminance weight “86” is assigned, and SF5, to which luminance weight “85” is assigned, are sequentially arranged following the subfield SF1. SG1 is arranged. Subsequent to the subfield group SG1, a subfield group SG2 in which SF6 to which the luminance weight “52” is assigned and SF7 to which the luminance weight “53” is assigned is sequentially arranged. Subsequent to the subfield group SG2, SF8 is assigned the fifth smallest luminance weight “16”, SF9 is assigned the fourth smallest luminance weight “8”, and third is the smallest luminance. The SF 10 assigned the weight “4”, the SF 11 assigned the second smallest luminance weight “2”, and the SF 12 assigned the smallest luminance weight “1” are sequentially arranged.

That is, a luminance weight indicated by a power of 2 is assigned to the first subfield group composed of subfields SF1 and SF8 to SF12 to which a relatively small luminance weight is assigned. Furthermore, luminance weights having values other than those indicated by powers of 2 are assigned to subfields belonging to the second subfield group such as subfield groups SG1 and SG2. At this time, the subfield SF1 to which the maximum luminance weight is assigned among the subfields belonging to the first subfield group is indicated by the sixth power of 2 which is the smallest, that is, 2 ^(6-1) . The assigned luminance weight “32” is assigned. Further, the subfield SF6 belonging to the second subfield group has the seventh smallest power of 2, that is, the luminance weight “52” smaller than the value “64” indicated by 2 ^(7-1) . Assigned.

  Here, in the subfield group SG1, the reset process Rc is provided only in the first subfields SF2 and SF6. Further, in the subfield group SG2, the reset process Rc is provided only in the first subfield SF6. Therefore, in the subfield group SG1 (or SG2), the subfield SF2 (or SF6) is the only opportunity for changing the discharge cell from the lighting mode to the extinguishing mode. Accordingly, in the subfield group SG1 or SG2, once the discharge cell is set to the lighting mode in any one subfield, the subsequent subfield SF5 (or SF7) in SG1 or SG2 is thereafter set. The lighting mode is maintained, and sustain discharge light emission is continuously performed in each subfield during that time.

That is, in the subfield group SG1,
Illuminated only with SF5 Illuminated with each of SF4 and SF5 Illuminated with each of SF3 to SF5 Illuminated with each of SF2 to SF5 Luminance components for five gradations are represented by five types of light emission patterns such as unlit for both SF2 to SF5.

In the subfield group SG2,
Illuminated only with SF7 Illuminated with each of SF6 and SF7 Luminance components for three gradations are represented by three types of light emission patterns such as both SF6 and SF7 being extinguished.

  Further, instead of the light emission drive sequence shown in FIG. 17, a light emission drive sequence as shown in FIG. 23 in which gradation drive is performed in 12 subfields may be adopted.

  The following luminance weights are assigned to each of the 12 subfields SF1 to SF12 shown in FIG.

SF1: 32
SF2: 86
SF3: 86
SF4: 86
SF5: 85
SF6: 2
SF7: 52
SF8: 53
SF9: 1
SF10: 16
SF11: 8
SF12: 4
That is, the subfield SF1 to which the sixth smallest luminance weight “32” is assigned is arranged at the head in the unit display period. Subsequent to the subfield SF1, SF2, SF3, SF4 to which the maximum luminance weight “86” is respectively assigned, SF5 to which the luminance weight “85” is assigned, and the second smallest luminance weight “2”. The subfield group SG1 in which SF6 to which "is assigned is sequentially arranged is arranged. Subsequent to the subfield group SG1, SF7 to which the luminance weight “52” is assigned, SF8 to which the luminance weight “53” is assigned, and SF9 to which the smallest luminance weight “1” is assigned are sequentially provided. Arranged subfield groups SG2 are arranged. Following this subfield group SG2, SF10 is assigned the fifth smallest luminance weight “16”, SF11 is assigned the fourth smallest luminance weight “8”, and third is the smallest luminance. The SFs 12 to which the weight “4” is assigned are sequentially arranged.

  That is, a luminance weight indicated by a power of 2 is assigned to the first subfield group including subfields SF1, SF6, and SF9 to SF12 to which a relatively small luminance weight is assigned. Luminance weights having values other than those indicated by powers of 2 are assigned to the other subfields SF2 to SF5, SF7, and SF8.

At this time, the subfield SF1 to which the maximum luminance weight is assigned among the subfields belonging to the first subfield group is indicated by the sixth power of 2 which is the smallest, that is, 2 ^(6-1) . The assigned luminance weight “32” is assigned. Further, in the subfield SF7 belonging to the second subfield group, the luminance weight “52” smaller than the seventh “power of 2”, that is, the value “64” indicated by 2 ^(7-1) is set. Is assigned.

  Here, in the subfield group SG1, the reset process Rc is provided only in the first subfield SF2. Further, in the subfield group SG2, the reset process Rc is provided only in the first subfield SF7. Therefore, in the subfield group SG1 (or SG2), the subfield SF2 (or SF7) is the only opportunity for changing the discharge cell from the lighting mode to the extinguishing mode. Accordingly, in the subfield group SG1 or SG2, once the discharge cell is set to the lighting mode in any one of the subfields, the subsequent subfield SF6 (or SF9) in SG1 or SG2 is set. The lighting mode is maintained, and sustain discharge light emission is continuously performed in each subfield during that time.

That is, in the subfield group SG1,
Lights only with SF6 Lights with each of SF5 and SF6 Lights with each of SF4 to SF6 Lights with each of SF3 to SF6 Lights with each of SF2 to SF6 Is expressed.

In the subfield group SG2,
Illuminated only by SF9 Illuminated by each of SF8 and SF9 Illuminated by each of SF7 to SF9 Luminance components for four gradations are represented by four types of light emission patterns such as all of SF7 to SF9 being extinguished.

  Further, instead of the light emission drive sequence shown in FIG. 17, a light emission drive sequence as shown in FIG. 24 in which gradation drive is performed in 10 subfields may be adopted.

  The following luminance weights are assigned to each of the ten subfields SF1 to SF10 shown in FIG.

SF1: 8
SF2: 24
SF3: 24
SF4: 23
SF5: 2
SF6: 14
SF7: 14
SF8: 13
SF9: 1
SF10: 4
That is, the subfield SF1 to which the fourth smallest luminance weight “8” is assigned is arranged at the head in the unit display period. Subsequent to the subfield SF1, SF2, SF3, to which the maximum luminance weight “24” is respectively assigned, SF4 to which the luminance weight “23” is assigned, and the second smallest luminance weight “2”. A subfield group SG1 in which assigned SFs 5 are sequentially arranged is arranged. Subsequent to the subfield group SG1, SF6 and SF7 to which the luminance weight “14” is assigned, SF8 to which the luminance weight “13” is assigned, and the smallest luminance weight “1” are assigned. A subfield group SG2 in which SF9 is sequentially arranged is arranged. Subsequent to the subfield group SG2, SF10 to which the third smallest luminance weight “4” is assigned is arranged.

  That is, a luminance weight indicated by a power of 2 is assigned to the first subfield group including subfields SF1, SF5, SF9, and SF10 to which a relatively small luminance weight is assigned. Luminance weights having values other than those indicated by powers of 2 are assigned to the other subfields SF2 to SF4 and SF6 to SF8.

At this time, the subfield SF1 to which the maximum luminance weight is assigned among the subfields belonging to the first subfield group is indicated by the fourth power of 2 that is the smallest power, that is, 2 ^(4-1) . The assigned luminance weight “8” is assigned. Further, in the subfield SF8 belonging to the second subfield group, the luminance weight “13” smaller than the fifth “5”, ie, the value “16” indicated by 2 ^(5-1) , is obtained. Is assigned.

  Here, in each of the subfield groups SG1 and SG2, the reset process Rc is provided only in the first subfields SF2 and SF6. Therefore, in the subfield group SG1 (or SG2), the subfield SF2 (or SF6) is the only opportunity for changing the discharge cell from the lighting mode to the extinguishing mode. Accordingly, in the subfield group SG1 or SG2, once the discharge cell is set to the lighting mode in any one of the subfields, the subsequent subfield SF5 (or SF9) in SG1 or SG2 is thereafter set. The lighting mode is maintained, and sustain discharge light emission is continuously performed in each subfield during that time.

That is, in the subfield group SG1,
Illuminated only with SF5 Illuminated with each of SF4 and SF5 Illuminated with each of SF3 to SF5 Illuminated with each of SF2 to SF5 Luminance components for five gradations are represented by five types of light emission patterns such as unlit for both SF2 to SF5.

In the subfield group SG2,
Illuminated only with SF9 Illuminated with each of SF8 and SF9 Illuminated with each of SF7 to SF9 Illuminated with each of SF6 to SF9 Luminance components for five gradations are expressed by five types of light emission patterns such as unlit for SF6 to SF9.

  In the above embodiment, when driving the PDP 10 based on the subfield method, the wall charges are erased from all the discharge cells in the reset process Rc, and the wall charges are selectively placed in the discharge cells in the address process Wc. The case where the so-called selective write address method is adopted in which is formed is described. However, the same applies to driving employing a so-called selective erasure address method in which wall charges are formed in all discharge cells in the reset process Rc and the wall charges remaining in the discharge cells are selectively erased in the address process Wc. It is applicable to. At this time, instead of the light emission drive sequences as shown in FIGS. 4, 8, 17, and 22 to 24, a light emission drive sequence in which the arrangement order of the subfields in the unit display period is reversed is adopted. For example, when the driving shown in FIGS. 4 to 7 is executed by adopting the selective erasing address method, the first subfield in the unit display period is set to SF7 as shown in FIG. 4, and this is followed by FIG. A light emission drive sequence in which SF6, SF5, SF4, SF3, SF2, and SF1 are sequentially arranged as shown in FIG. When the selective erasure address method is used and the driving shown in FIGS. 8 to 16 is executed, the first subfield in the unit display period is set to SF11 as shown in FIG. 8, and this is followed by FIG. The light emission driving sequence in which SF10, SF9, SF8, SF7, SF6, SF5, SF4, SF3, SF2, and SF1 are sequentially arranged as shown in FIG.

It is a figure which shows an example of the light emission drive sequence based on a subfield method, and the light emission pattern which a false outline generate | occur | produces. It is a figure which shows the light emission pattern which suppresses generation | occurrence | production of a false outline. 1 is a diagram illustrating a configuration of a plasma display device including a panel driving unit that performs gradation driving of a plasma display panel according to a driving method of the present invention. It is a figure which shows an example of the light emission drive sequence at the time of employ | adopting the selective writing address method and carrying out gradation drive of the plasma display panel. FIG. 5 is a diagram showing a light emission pattern when the plasma display panel is driven in gradation based on the light emission drive sequence shown in FIG. 4. FIG. 5 is a diagram showing a light emission pattern when the plasma display panel is driven in gradation based on the light emission drive sequence shown in FIG. 4. FIG. 5 is a diagram showing a light emission pattern when the plasma display panel is driven in gradation based on the light emission drive sequence shown in FIG. 4. It is a figure which shows another example of the light emission drive sequence at the time of employ | adopting the selective writing address method and carrying out a gradation drive of the plasma display panel. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows an example of the light emission drive sequence based on the selective writing address method in consideration of reverse gamma correction. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the light emission pattern at the time of carrying out the gradation drive of the plasma display panel based on the light emission drive sequence shown in FIG. It is a figure which shows the modification of the light emission drive sequence shown in FIG. It is a figure which shows the modification of the light emission drive sequence shown in FIG. It is a figure which shows the modification of the light emission drive sequence shown in FIG.

Brief description of symbols

10 PDP
20 Address driver 30 Y electrode driver 40 X electrode driver 50 Drive control circuit

Claims (6)

A plasma display driving method for driving a plasma display panel in which a plurality of discharge cells corresponding to each pixel are arranged in a matrix in N sub-fields (N: an integer of 2 or more) per unit display period Because
Each of the subfields includes an address step of setting each discharge cell to one of a lighting mode and a non-lighting mode by selectively discharging each discharge cell according to an input video signal; A sustain step of repeatedly discharging only the discharge cells set to the lighting mode a number of times corresponding to the luminance weight assigned to the subfield,
Each of the subfields is assigned a first subfield group composed of subfields each assigned a luminance weight of a value indicated by a power of 2, and a luminance weight other than a value indicated by a power of 2 Belonging to one of the second subfield groups of subfields,
In all the subfields in the first subfield group, the discharge cell expresses a brightness level that is one gradation higher than the brightness level set corresponding to the light emission pattern set in the lighting mode. In this case, the discharge cell is set to the lighting mode in at least one subfield in the second subfield group and in at least one subfield in the first subfield group. How to drive the display. One subfield in the second subfield group is assigned a luminance weight greater than the maximum among the luminance weights assigned to each subfield belonging to the first subfield group. ,
When expressing a luminance level that is one gradation higher than the luminance level expressed when the discharge cells are set in the lighting mode in all subfields belonging to the first subfield group, The discharge cell is set to the lighting mode in the one subfield in the second subfield group and in at least one subfield belonging to the first subfield group. Driving method of plasma display. The maximum luminance weight value among the luminance weights assigned to each of the subfields belonging to the first subfield group is the Kth (Kth) luminance luminance assigned to each of the N subfields. : An integer greater than or equal to 1)
2. The driving method of the plasma display according to claim 1, wherein a luminance weight value assigned to the first subfield in the second subfield group is a (K + 1) th smallest value. Among the subfields belonging to the first subfield group, the subfield to which the maximum luminance weight is assigned is assigned a luminance weight indicated by 2 ^(K-1) ,
The driving method of a plasma display according to claim 3, wherein the assigned small becomes luminance weight than the value indicated by the 2 ^K to the first subfield of said second sub-field group.   Among the subfields belonging to the first subfield group, the subfield to which the maximum luminance weight is assigned, and among the subfields belonging to the first subfield group, the second largest luminance weight is assigned. 5. The method of driving a plasma display according to claim 1, wherein each of the subfields belonging to the second subfield group is arranged continuously between the subfields of the second subfield group. . Each of the subfields belonging to the first subfield group further includes a reset step of initializing each of the discharge cells to one of the lighting mode and the extinguishing mode by discharging all the discharge cells. Including
6. The plasma display driving method according to claim 5, wherein only the subfield arranged at the head of each of the subfields belonging to the second subfield group further includes the reset step.

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