Dynamic keep-alive to improve plasma-panel write and sustain margins

Keep-alive border cells are used to prime addressed cells of a plasma panel to improve the write margin. Currently, the time relationship between the drive waveform for the keep-alive border and the write waveform is kept fixed or static. The effectiveness of the static keep-alive arrangement is very limited: e.g., an experiment is described showing that across a 2.4-in span (between keep-alive border and address cell), this breakdown voltage increases by 14 percent and the ionization time almost doubles. These spatial variations greatly reduce the operating margins. A dynamic keep-alive scheme has been designed to provide spatial uniformity of breakdown voltage and ionization time, and thus to improve the write margins. It can be implemented by simply using the most-significant bits of an address to control the firing of a single keep-alive driver. Experimental results show that for a 5 × 5-in panel, the dynamic keep-alive scheme provides about 50-percent improvement in write margin over the static keep-alive arrangement. Some of this write margin can be traded to provide increased sustain margins.