KR20010035881A - Method of Driving Plasma Display Panel - Google Patents

Abstract

PURPOSE: A method for driving a plasma display panel is provided to minimize the discharge number generated in a reset period by supplying an integral wave reset pulse for a reset period. CONSTITUTION: The method includes a reset period which initializes a total screen, an address period which selects a cell, and a sustain period which sustains a discharge of a selected cell. A positive priming pulse(PRMP) is supplied to scan/sustain electrode lines(Y1-Ym). Negative scan pulses(-SP1 - -SPm) and a sustain pulse(SUSP) are sequentially supplied thereto. A negative priming pulse(-PRMP) is supplied to common sustain electrode lines(Z1-Zm) and then sustain pulse(SUSP) is supplied thereto. Priming pulses(PRMP,-PRMP) are supplied to the scan/sustain electrode lines(Y1-Ym) and the common sustain electrode lines(Z1-Zm) included in m scan lines. Widths of a scan pulse supplied for an address period are differently set according to a scanning time of each scan line.

Description

Driving Method of Plasma Display Panel {Method of Driving Plasma Display Panel}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a plasma display panel, and more particularly, to a method for driving a plasma display panel having uniform discharge characteristics.

Recently, a plasma display panel (hereinafter referred to as "PDP"), which is easy to manufacture a large panel, has attracted attention as a flat panel display device. The PDP displays an image by adjusting the discharge period of each pixel. As such a PDP, a three-electrode AC surface discharge type PDP having three electrodes and driven by an AC voltage is representative.

Referring to FIG. 1, a discharge cell of a three-electrode alternating surface discharge type PDP is formed on a scan / sustain electrode 12Y and a common sustain electrode 12Z formed on an upper substrate 10, and a lower substrate 18. An address electrode 20X is provided. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan / sustain electrode 12Y and the common sustain electrode 12Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used. The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode 20X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode 20X is formed in the direction crossing the scan / sustain electrode 12Y and the common sustain electrode 12Z. The partition wall 24 is formed in parallel with the address electrode 20 to prevent the ultraviolet rays and the visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. Inert gas for gas discharge is injected into the discharge space provided between the upper and lower plates and the partition wall.

Referring to FIG. 2, a driving apparatus of a three-electrode alternating surface discharge type PDP includes m / n discharge cells 1 having scan / sustain electrode lines Y1 to Ym, common sustain electrode lines Z1 to Zm, and PDP 30 arranged in a matrix so as to be connected to the address electrode lines X1 to Xn, and the scan / sustain electrode driver 32 for driving the scan / sustain electrode lines Y1 to Ym, in common. The common sustain electrode driver 34 for driving the sustain electrode lines Z1 to Zm, the odd-numbered address electrode lines X1, X3, ..., Xn-3, Xn-1 and the even-numbered address electrode lines First and second address electrode drivers 36A and 36B are provided to drive (X2, X4, ..., Xm-2, Xm) separately. The scan / sustain electrode driver 32 supplies scan pulses and sustain pulses sequentially to the scan / sustain electrode lines Y1 to Ym so that the discharge cells 1 are sequentially scanned in line units, and m × The discharge in each of the n discharge cells 1 is continued. The common sustain electrode driver 34 supplies sustain pulses to all of the common sustain electrode lines Z1 to Zn. The first and second address electrode drivers 36A and 36B supply image data to the address electrode lines X1 to Xm in synchronization with the scan pulse. The first address electrode driver 36A supplies image data to the odd-numbered address electrode lines X1, X3, ..., Xn-3, Xn-1, while the second address electrode driver 36B is the even-numbered address. Image data is supplied to the electrode lines X2, X4, ..., Xn-2, Xn.

The three-electrode AC surface discharge type PDP realizes gray levels by adjusting the amount of light depending on the discharge time. To this end, the three-electrode AC surface discharge type PDP displays an image by a driving method of ADS (Addressing Display Separated). The ADS PDP driving method divides one frame into a plurality of subfields according to the gradation level to be implemented, and each subfield is divided into an address period and a sustain period different from each other. For example, when the image is to be displayed with 256 gray levels, a frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. In addition, each of the eight subfields SF1 to SF8 is divided into an address period and a sustain period. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period is 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. Is increased. In this way, since the sustain period is different in each subfield, the gray scale of the image is expressed by adjusting the sustain period of each subfield, that is, the number of sustain discharges.

3 shows a drive waveform of a three-electrode alternating surface discharge type PDP.

Referring to FIG. 3, each of the subfields SF1 to SF8 of the three-electrode AC surface discharge type PDP is divided into a reset period, an address period, and a sustain period to display an image. During the reset period, the full screen is written by the writing discharge between the address electrode 20X and the common sustain electrode 12Z, and the sustain discharge and the erasing discharge are successively generated following the writing discharge to uniformly spread the discharge cells on the full screen. Wall charges are formed. In the address period, the scan pulse SP is sequentially applied to the scan / sustain electrode line Y, and the address pulse AP including data is supplied to the address electrode line X in synchronization with the scan pulse SP. do. In the sustain period, a sustain pulse SSUS having the same duty ratio is applied to the scan / sustain electrode 12Y and the common sustain electrode 12Z to maintain the discharge of the discharge cells 1 selected by the address discharge.

However, the conventional PDP generates a plurality of discharges supplied in the reset period. At this time, the discharge cells 1 emit light together with the discharge to increase the luminance value of the black level. Accordingly, the conventional PDP has a problem that contrast is inhibited. In addition, in the conventional PDP, since each scan line is scanned in a line sequential manner, wall charges and charged particles generated at the address discharge are different for each scan line. In other words, if the scan lines of the PDP are 480 lines in total, the period between the supply time of the scan pulse SP and the supply time of the sustain pulse SSUS to the first scan / sustain electrode line Y1 is longest. Then, the period between the supply time of the scan pulse SP and the supply time of the sustain pulse SUSP to the scan / sustain electrode lines Y2 to Y480 of the scan lines is gradually shortened. As a result, in the discharge cells 1 corresponding to the first scan line, many wall charges and charged particles generated during address discharge by the address pulse AP and the scan pulse SP are decay, while Relatively few wall charges and charged particles are decayed in the discharge cells 1 corresponding to the scan lines. As such, when the wall charges and charged particles generated during the address discharge are decayed in different amounts for each scan line, the same discharge characteristics may not be maintained in each scan line. Then, in the sustain period during which the sustain pulse (SUSP) is supplied, the remaining amount of the wall charges and the charged particles is different for each scanning line according to the scanning point, thereby causing miss discharge or mis-discharge.

Accordingly, an object of the present invention is to provide a method of driving a PDP that has a uniform discharge characteristic.

Another object of the present invention is to provide a method for driving a PDP to improve contrast.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

FIG. 2 is a diagram illustrating a plasma display panel in which discharge cells shown in FIG. 1 are arranged in a matrix form and a driving device thereof;

FIG. 3 is a driving waveform diagram for explaining a driving method of the plasma display panel shown in FIG. 1.

4 is a driving waveform diagram for explaining a driving method of the plasma display panel according to the first embodiment of the present invention;

5 is a driving waveform diagram for explaining a method of driving a plasma display panel according to a second embodiment of the present invention;

Fig. 6 is a diagram showing block divisions of the plasma display panel according to the third and fourth embodiments of the present invention.

7 is a driving waveform diagram for explaining a method of driving a plasma display panel according to a third embodiment of the present invention;

8 is a driving waveform diagram for explaining a method of driving a plasma display panel according to a fourth embodiment of the present invention;

<Description of the code | symbol about the principal part of drawing>

10: upper substrate 12Y, 22Y: scanning / sustain electrode

12Z, 22Z1,22Z2: common sustain electrode 14,22: dielectric layer

16: protective film 18: lower substrate

20X: address electrode 24: partition wall

26: phosphor

In order to achieve the above objects, the driving method of the PDP according to the present invention is characterized in that the pulse width of the scan pulse supplied in the address period is set differently according to the scanning time of each scan line.

The driving method of the PDP according to the present invention supplies a priming sustain pulse having a lower voltage level than the sustain pulse which causes the sustain discharge at the beginning of the sustain period, and the pulse width of the priming sustain pulse depends on the scanning point of each scan line. It is characterized in that it is set differently.

In the method of driving a PDP according to the present invention, the panel is divided into at least two blocks each including a plurality of scan lines, and a pulse width of a scan pulse supplied in an address period is set differently according to the scanning time of each block. Characterized in that it comprises a step.

A method of driving a PDP according to the present invention comprises dividing a panel into at least two blocks each including a plurality of scanning lines, and a priming sustain having a voltage level lower than a sustain pulse which causes a sustain discharge at the beginning of the sustain period. And supplying a pulse to the blocks, wherein the pulse width of the priming sustain pulse is set differently according to the scanning time of each block.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 8.

Referring to FIG. 4, in the driving method of the PDP according to the first embodiment of the present invention, after supplying the positive priming pulse PRMP to the scan / sustain electrode lines Y1 to Ym, the negative scan pulse ( -SP1 to -SPm) and sustain pulse (SUSP) are supplied sequentially. After the negative priming pulse (-PRMP) is supplied to the common sustain electrode lines Z1 to Zm, the sustain pulse SSUS is supplied. The address electrode line X is supplied with an address pulse AP including video data.

First, priming pulses PRMP and -PRMP are supplied to scan / sustain electrode lines Y1 to Ym and common sustain electrode lines Z1 to Zm included in all m scan lines. Here, the priming pulses (PRMP, -PRMP) has an integral wave form with a small slope of the rising edge and the falling edge so that the voltage level of the priming pulses (PRMP, -PRMP) increases slowly and descends slowly. The priming pulses PRMP and -PRMP cause reset discharges to the scan / sustain electrode lines Y1 to Ym and the common sustain electrode lines Z1 to Zm, and wall charges and charged particles are generated by the reset discharges. Are generated. At this time, negative wall charges are accumulated in the scan / sustain electrode lines Y1 to Ym, while positive wall charges are accumulated in the common sustain electrode lines Z1 to Zm. The wall charges generated by the reset discharge are not recombined and continuously disappear after gradually rising and falling in the priming pulses (PRMP, -PRMP). At this time, the neutral particles are present in the discharge cell for a longer time than the negative or positive charged particles. These neutral particles lower the voltage required for discharge during address discharge.

In the address period, scan pulses SP1 to SPm are sequentially supplied to each of the scan / sustain electrode lines Y1 to Ym. Here, each of the scan pulses SP1 to SPm has a larger pulse width as the scanning time is faster. That is, the pulse width of the scan pulse SP1 supplied to the first scan / sustain electrode lines Y1 is the largest, and the scan pulses supplied to the second to m-th scan / sustain electrode lines Y2 to Ym. The pulse width of (SP2 to SPm) gradually decreases. The address electrode lines X1 to Xn are supplied with an address pulse AP including video data to be synchronized with each of the scan pulses SP1 to SPm. Then, the discharge cells are discharged by the voltage difference between the scan pulses SP1 to SPm and the address pulses AP added to the wall charges formed by the reset period and the wall voltages. At this time, the neutral particles held from the reset period are ionized by the voltage when the scan pulses SP1 to SPm and the address pulse AP are supplied to the discharge cell. Since the width of the scan pulse supplied to the scan line with a fast scanning point and the width of the scan pulse supplied to a scan line with a relatively slow scanning time are large, the discharge cells of the scan line with a fast scanning time are as large. Wall charges and charged particles are generated, and relatively small amount of wall charges and charged particles are generated in the discharge cells of the scanning line having a relatively late scanning time. Accordingly, the wall charges and the charged particles are compensated by the amount of the wall charges and the charged particles that disappear in the discharge cells of the scan lines having the fastest scanning time. As a result, at the beginning of the sustain period, the discharge cells of all the scan lines remain uniform in wall charge and charged particles, so that the discharge conditions are the same.

During the sustain period, priming sustain pulses (PSUSP) and sustain pulses (SUSP) are sequentially supplied to the scan / sustain electrode lines (Y1 to Ym), and sustain pulses (SUSP) to the common sustain electrode lines (Z1 to Zm). Is supplied. The priming sustain pulse PSUSP is commonly supplied to all the scan / sustain electrode lines Y1 to Ym at the start of the sustain period. The priming sustain pulse PSUSP has a lower amplitude and a smaller pulse width than the sustain pulse SSUS, and is added to and supplied to the first sustain pulse SSUS. This priming sustain pulse (PSUSP) causes the discharge cells to be filled with more wall charges and charged particles at the beginning of the sustain period. When the sustain pulse SSUS is supplied after the priming sustain pulse PSUSP, the discharge cells turned on in the address period are strongly discharged.

5 shows a driving waveform for explaining a method for driving a PDP according to a second embodiment of the present invention.

Referring to FIG. 5, in the reset period, priming pulses having an integral wave type are included in the scan / sustain electrode lines Y1 to Ym and the common sustain electrode lines Z1 to Zm included in all m scan lines. PRMP, -PRMP). The priming pulses PRMP and -PRMP cause a reset discharge to occur in the scan / sustain electrode lines Y1 to Ym and the common sustain electrode lines Z1 to Zm, and the wall discharge and charged particles are generated by the reset discharge. Are generated. The wall charges generated by the reset discharge gradually disappear due to the long rising and falling sections of the priming pulses (PRMP, -PRMP), and the neutral particles exist in the discharge cells for a long time.

In the address period, scan pulses SP having the same amplitude and pulse width are sequentially supplied to each of the scan / sustain electrode lines Y1 to Ym. The address pulses AP including video data are supplied to the address electrode lines X1 to Xn in synchronization with the scan pulse SP. Then, the discharge cells are discharged by the voltage difference between the scan pulses SP1 to SPm and the address pulses AP added to the wall charges formed by the reset period and the wall voltages. At this time, the wall charges and charged particles in the discharge cells included in each scan line has a variation in the amount of disappearance according to the scanning time. That is, since the discharge cells included in the first scan line have a long time between the scanning point and the start point of the sustain period, a large amount of wall charges and charged particles can be decayed, while the discharge cells included in the last scan line Because of the short time between the scanning time and the start of the sustain period, the wall charges and charged particles hardly disappear and are maintained until the start of the sustain period. Accordingly, since the wall voltage of the discharge cells turned on by the address discharge in the scan line with a fast scanning time is low, sustain discharge may not occur due to the sustain pulse SUSP supplied in the sustain period. In addition, since the address discharge does not occur in the scan line having a slow scanning time, that is, the wall voltage of the discharge cells maintaining the off state is high, the discharge may be caused by the sustain pulse SSUS. In other words, miss discharge or false discharge may occur depending on the deviation of the scanning time of each scan line.

During the sustain period, the priming sustain pulses (PSUSP1 to PSUSPm) and the sustain pulses (SUSP) having different pulse widths are sequentially supplied to the scan / sustain electrode lines (Y1 to Ym), and the common sustain electrode lines (Z1 to Zm) is supplied with a sustain pulse (SUSP). Each priming sustain pulse (PSUSP1 to PSUSPm) has a lower amplitude than the sustain pulse (SUSP), and is added to and supplied to the first sustain pulse (SUSP).

Priming sustain pulse (PSUSP) has a large pulse width in the scan / sustain electrode lines (Y1, Y2, ...) included in the scan line with a fast scanning point, and discharges included in the scan lines with a fast start time. It will compensate for the wall charge of the cells and the large amount of decay of the charged particles. On the other hand, the priming sustain pulses (PSUSP1 to PSUSPm) supplied to the scan / sustain electrode lines (..., Ym-1, Ym) included in the slow scanning line have a relatively small pulse width. Each of the scanning lines has the same discharge condition by the priming sustain pulse (PSUSP1 to PSUSPm). When the sustain pulse SSUS is supplied following the priming sustain pulses PSUS P1 to PSUS Pm, the discharge cells turned on during the address period are strongly discharged.

On the other hand, the decay amount of the wall charges and charged particles that vary in each scan line according to the scanning time may be compensated by modulating the pulse width of the scan pulse or the flying sustain pulse for each scan line, as in the above-described embodiments. It may be compensated for each block including a. In this case, as shown in FIG. 6, the PDP 30 is driven by being divided into blocks BL1 to BL4 each including a plurality of scan lines. Scan / stain electrode lines BY1 to BY4 included in the scan lines in the first to fourth blocks BL1 to BL4 may have wall charges different from the scan lines in the blocks BL1 to BL4 according to the scanning time. And scan pulses or priming sustain pulses having different pulse widths to compensate the decay amount of the charged particles.

7 is a driving waveform for explaining a method of driving a PDP according to a third embodiment of the present invention.

6 and 7, the positive priming pulse PRMP in the form of an integrated wave is supplied to the scan / sustain electrode lines BY1 to BY4 in each of the blocks BL1 to BL4, and then, according to a scanning time point. Scan pulses (SP1 to SP4), priming sustain pulses (PSUSP), and sustain pulses (SUSP) modulated with different pulse widths are sequentially supplied. The negative sustaining pulse SUPR is supplied to the common sustain electrode lines BZ1 to BZ4 in each of the blocks BL1 to BL4 after an integrated wave type negative priming pulse (-PRMP). The address pulses AP including video data are supplied to the address electrode lines X1 through Xn.

First, in the reset period, as described above, the priming pulse PRMP of the integrated wave type is formed on the scan / sustain electrode lines BY1 to BY4 and the common sustain electrode lines BZ1 to BZ4 in each of the blocks BL1 to BL4. -PRMP) is supplied to reset discharge.

Subsequently, scan pulses SP1 to SP4 having different pulse widths are sequentially supplied to the scan / sustain electrode lines BY1 to BY4 of the blocks BL1 to BL4 in the address period. Here, the pulse width of the scan pulse SP1 supplied to the first block BL1 is the largest, and the pulse widths of the scan pulses SP2 to SP4 supplied to the second to fourth blocks BL2 to BL4 are progressive. Becomes smaller. The address electrode lines X1 to Xn are supplied with an address pulse AP including video data to be synchronized with each of the scan pulses SP1 to SP4 to turn on the corresponding discharge cells by addressing the selected discharge cells. Let's go. The scan pulses SP1 and SP2 having a large pulse width compensate for the wall charges and charged particles by the amount of wall charges and charged particles that are lost in the discharge cells of the scan lines in the first blocks BL1 and BL2 having a fast scanning point. Done. As a result, at the beginning of the sustain period, the discharge cells in each of the blocks BL1 to BL4 remain uniform in wall discharge and charged particles, so that the discharge conditions are the same.

During the sustain period, the scanning / sustain electrode lines BY1 to BY4 in the blocks BL1 to BL4 are supplied with a priming sustain pulse PSUSP having a smaller amplitude and pulse width than the sustain pulse SUSP, and then the sustain pulse. (SUSP) is supplied. The sustain pulse SSUS is supplied to the common sustain electrode lines BZ1 to BZ4.

8 illustrates a driving waveform for explaining a method of driving a PDP according to a fourth embodiment of the present invention.

6 and 8, in the reset period, priming pulses of the integral wave form are formed on the scan / sustain electrode lines BY1 to BY4 and the common sustain electrode lines BZ1 to BZ4 in the blocks BL1 to BL4. When (PRMP, -PRMP) is supplied, a reset discharge occurs.

In the address period, scan pulses SP having the same amplitude and pulse width are sequentially supplied to the scan / sustain electrode lines BY1 to BY4 in the blocks BL1 to BL4. According to the scanning time of this address period, the wall charges of the discharge cells in each of the blocks BL1 to BL4 and the decay amount of the charged particles may vary.

During the sustain period, priming sustain pulses (PSUSP1 to PSUSPm) and sustain pulses (SUSP) having different pulse widths are sequentially supplied to the scan / sustain electrode lines BY1 to BY4 in the blocks BL1 in BL1. The sustain pulse SSUS is supplied to the common sustain electrode lines BZ1 to BZ4. Here, the blocks BL1 and BL2 having a high wall charge and decay amount are supplied with the pristine sustain pulses PSUSP1 and PSUSP2 having a large pulse width to compensate for the attenuation, while the blocks having a relatively low decay amount BL3. Priming sustain pulses PSUSP3 and PSUSP4 having a small pulse width are supplied to BL4. Following the priming sustain pulses PSUSP1 to PSUSP4, the sustain pulses SUPS are supplied, so that the sustain cells are strongly discharged in the address period.

As described above, the driving method of the PDP according to the present invention supplies scan pulses having different pulse widths or priming sustain pulses having different pulse widths to the scan lines to vary the scanning time for each scan line. The difference between the wall charges and the charged particles are eliminated. Accordingly, the PDP of the present invention not only has all discharge cells having uniform discharge characteristics during sustain discharge, but also prevents mis-discharge and miss discharge and sufficiently secures a driving margin. The driving method of the PDP according to the present invention can improve the contrast by minimizing the number of discharges occurring in the reset period by supplying the integral pulse type reset pulse only once in the reset period.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. For example, the decay amounts of the wall charges and charged particles, which vary for each scan line according to the deviation of the scanning time point, may be compensated by both the pulse width adjustment of the address pulse and the pulse width adjustment of the priming sustain pulse (PSUSP). Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (11)

A driving method of a plasma display panel comprising a reset period for initializing a full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of a selected cell, And the pulse width of the scan pulse supplied in the address period is set differently according to the scanning time of each scan line. The method of claim 1, The pulse width of the scan pulse supplied to the scan line in which the scanning point is supplied is set large, while the pulse width of the scan pulse supplied to the scan line in which the scanning time is relatively set is small. Driving method. The method of claim 1, The reset pulse causing reset discharge in the reset period is supplied only once to each scan line. And the reset pulse has an integral wave shape such that a rising period and a falling period are long. The method of claim 1, And a priming sustain pulse having a pulse width and a voltage level smaller than the sustain pulse causing sustain discharge at the start of the sustain period. A driving method of a plasma display panel comprising a reset period for initializing a full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of a selected cell, Supplying a priming sustain pulse having a lower voltage level than the sustain pulse causing sustain discharge at the beginning of the sustain period, The pulse width of the priming sustain pulse is set differently according to the scanning time of each scan line. The method of claim 5, While the pulse width of the priming sustain pulse supplied to the scan line with the scanning point is set to be large, the pulse width of the priming sustain pulse supplied to the scan line with the scanning point is set to be small. How to drive the panel. The method of claim 5, The reset pulse causing reset discharge in the reset period is supplied only once to each scan line. And the reset pulse has an integral wave shape such that a rising period and a falling period are long. The method of claim 5, And a pulse width of a scan pulse supplied in the address period is equally supplied to each scan line. The method of claim 5, And the pulse width of the scan pulse supplied in the address period is set differently according to the scanning time of each scan line. A driving method of a plasma display panel comprising a reset period for initializing a full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of a selected cell, Dividing the panel into at least two blocks each comprising a plurality of scan lines; And setting a pulse width of a scan pulse supplied in the address period differently according to a scanning time point of each of the blocks. A driving method of a plasma display panel comprising a reset period for initializing a full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of a selected cell, Dividing the panel into at least two blocks each comprising a plurality of scan lines; Supplying the blocks with a priming sustain pulse having a lower voltage level than the sustain pulse causing sustain discharge at the beginning of the sustain period, The pulse width of the priming sustain pulse is set differently according to the scanning time of the blocks.