Driving method for plasma display panel, and plasma display device

A plasma display apparatus comprising:

• a plasma display panel having a plurality of discharge cells, each of the discharge cells having a display electrode pair and a data electrode, th e display electrode pair including a scan electrode and a sustain electrode, the plasma display panel displaying gradations in a manner such that a plurality of subfields, each including an address period and a sustain period, is set in one field, and in a subfield where an address discharge has occurred in the address period, sustain discharges in a number of times in response to a luminance weight set for each subfield are generated in the sustain period;
• and
• an image signal processing circuit for converting an input image signal into image data showing light emission and no light emission at each discharge cell in each subfield in response to a magnitude of a gradation value represented in the one field,
• wherein, when the gradation value of one discharge cell of two adjacent discharge cells is equal to or larger than a predetermined threshold gradation value, and that of the other discharge cell is a gradation value at which the discharge cell is lit only in a predetermined subfield, the image signal processing circuit changes the gradation value of the other discharge cell to a gradation value at which the discharge cell is unlit in all the subfields or a gradation value at which the discharge cell is lit only in the predetermined subfield and a subfield whose luminance weight is heavy next to that of the predetermined subfield.