Plasma display device and plasma display panel driving method

A plasma display device comprising:

• a plasma display panel,
• the plasma display panel being driven by a subfield method in which a plurality of subfields is set in one field, each of the subfields has an initializing period, an address period, and a sustain period, a luminance weight is set for each of the subfields, and sustain pulses corresponding in number to the luminance weight are generated in the sustain period for gradation display,
• the plasma display panel having a plurality of discharge cells, the discharge cells having display electrode pairs, each of the display electrode pairs being formed of a scan electrode and a sustain electrode;
• an image signal processing circuit for converting an input image signal into image data showing light emission and no light emission in the discharge cells in each subfield;
• a sustain pulse generating circuit for generating and applying the sustain pulses alternately to the scan electrodes and the sustain electrodes of the display electrode pairs in the sustain period, the sustain pulse generating circuit including:
• a power recovery circuit for causing resonance between an interelectrode capacitance of the display electrode pairs and an inductor, and thereby causing the sustain pulses to rise or fall;
• and
• a clamp circuit for clamping a voltage of the sustain pulses to a power supply voltage or a base voltage;
• an all-cell light-emitting rate detecting circuit for detecting a rate of the number of discharge cells to be lit with respect to the number of all discharge cells in a display area of the plasma display panel, as an all-cell light-emitting rate, in each subfield;
• and
• a partial light-emitting rate detecting circuit for dividing the display area of the plasma display panel into a plurality of regions, and detecting a rate of the number of discharge cells to be lit with respect to the number of discharge cells in each of the regions, as a partial light-emitting rate, in each subfield,
• the sustain pulse generating circuit generates the plurality of sustain pulses where lengths of at least one of a rising period and a falling period are different, and generates the sustain pulses by selecting a driving pattern according to the all-cell light-emitting rate and the partial light-emitting rate, among a plurality of driving patterns where the sustain pulses are generated in different combinations,
• the image signal processing circuit includes:
• the number of lit cells calculator for calculating the number of discharge cells to be lit in each display electrode pair, in each subfield;
• a load value calculator for calculating a load value of each of the discharge cells, according to the calculation result in the number of lit cells calculator;
• a correction gain calculator for calculating a correction gain of each of the discharge cells, according to the calculation result in the load value calculator, the driving pattern, and a position of the discharge cell;
• and
• a corrector for subtracting a multiplication result of output from the correction gain calculator and the input image signal, from the input image signal;
• and
• the load value calculator and the correction gain calculator calculate the correction gain by
• setting a lighting state of each of the discharge cells in each of the subfields such that lighting is 1 and non-lighting is 0;
• multiplying the calculation result in the number of lit cells calculator, the luminance weight set for corresponding one of the subfields, and the lighting state in one of the discharge cells of which correction gain is to be calculated, and calculating a total sum of the multiplication results in the respective subfields as the load value;
• multiplying the number of discharge cells formed on the display electrode pair, the luminance weight set for corresponding one of the subfields, and the lighting state in the discharge cell of which correction gain is to be calculated, and calculating a total sum of the multiplication results in the respective subfields as a maximum load value;
• and
• subtracting the load value from the maximum load value, and dividing the subtraction result by the maximum load value.