Plasma display apparatus
A AC type plasma display apparatus has been disclosed, which satisfies various requirements such as the number of gradations that can be displayed, the display luminance, and the upper limit of power and, further, the efficiency of light emission and the luminance can be increased as much as possible and the display quality of which is not deteriorated. In the plasma display apparatus, a frame is composed of plural subfields, an image is displayed by causing a sustain discharge to occur in each subfield, the sustain discharge can be caused to occur by at least a first sustain waveform and a second sustain waveform different from the first sustain waveform, and the ratio of the first sustain waveform to the second sustain waveform changes, both waveforms being used to cause the sustain discharge to occur in each subfield.
1 . An AC type plasma display apparatus comprising plural subfields constituting a frame and displaying an image by causing a sustain discharge to occur in each subfield, wherein the sustain discharge can be caused to occur by at least a first sustain waveform and a second sustain waveform different from the first sustain waveform, and the ratio of the first sustain waveforms to the second sustain waveforms changes.
2 . The plasma display apparatus as set forth in claim 1 , wherein the second sustain waveform has a period longer than the period of the first sustain waveform and the sustain discharge caused by the second sustain waveform produces a luminance or a light emission efficiency higher than those produced by the sustain discharge caused by the first sustain waveform.
3 . The plasma display apparatus as set forth in claim 1 , wherein the number of times of application of the first sustain waveform and the second sustain waveform in the plural subfields in a frame is determined so that the power is equal to or less than a predetermined value.
4 . The plasma display apparatus as set forth in claim 3 , wherein a circuit for detecting the display load ratio is comprised and the number of times of application of the first sustain waveform and the second sustain waveform in the plural subfields in a frame is determined so that the power is equal to or less than the predetermined value based on the detected display load ratio.
5 . The plasma display apparatus as set forth in claim 1 , wherein the ratio of the first sustain waveforms to the second sustain waveforms in each subfield is determined so that the display luminance or the efficiency of light emission is as high as possible.
6 . The plasma display apparatus as set forth in claim 4 , wherein only the first sustain waveform is applied when the display load ratio is low.
7 . The plasma display apparatus as set forth in claim 1 , wherein the ratio of the first sustain waveforms to the second sustain waveforms in each subfield is determined so that the luminance ratio among respective subfields is substantially constant.
8 . The plasma display apparatus as set forth in claim 1 , wherein the ratio of the first sustain waveforms to the second sustain waveforms in each subfield is determined so that the display luminance changes smoothly.
9 . The plasma display apparatus as set forth in claim 1 , wherein at least one of the pulse width and the pulse interval of the second sustain waveform is greater than that of the first sustain waveform.
10 . The plasma display apparatus as set forth in claim 1 , wherein the second sustain waveform causes two sustain discharges to occur in one of polarity changes.
11 . The plasma display apparatus as set forth in claim 1 , wherein, after applying a high voltage for a short time, the second sustain waveform maintains a state in which a voltage slightly lower than the high voltage is being applied in one of polarity changes.
12 . An AC type plasma display apparatus comprising plural subfields constituting a frame and displaying an image by causing a sustain discharge to occur in each subfield, wherein:
the sustain discharge can be caused to occur by at least a first sustain waveform and a second sustain waveform different from the first sustain waveform and capable of causing the sustain discharge to occur with higher luminance or higher light emission efficiency; and
when the display luminance when the sustain discharge is caused to occur only by the first sustain waveform is substantially the same as the display luminance when the sustain discharge is caused to occur by using only the maximum number of second sustain waveforms that can be used under drive time conditions, the use of the first sustain waveform is switched to the use of the second sustain waveform.