Plasma panel erase apparatus

Claim 1

In a gas discharge display matrix of the type having a chamber containing ionizable gas and formed of a dielectric, and having a plurality of spaced-apart first electrodes on a first side of the chamber and a plurality of spaced-apart second electrodes on a second side of the chamber and nonparallel to the first electrodes, said electrodes located so as to interpose an ionizable gas volume and a portion of the dielectric between each first electrode and each second electrode; and having a pulse generator for sustaining light emission from all gas volumes having a wall charge voltage exceeding a predetermined value by applying sustaining pulses of predetermined voltage to at least one of the pluralities of first and second electrodes causing voltage potential on the first electrodes to alternately rise above and fall below the potential on the second electrodes; wherein the invention comprises improved apparatus for extinguishing light emission from the selected gas volume between a selected first and a selected second electrode specified by first and second erase select signals, respectively, comprising: a. means for interrupting for a preselected time application of sustaining pulses after substantial completion of a selected sustaining pulse to the first electrodes, responsive to an erase select signal; b. first switch means for connecting at least the selected first electrode to a reference voltage responsive to a first switch closure signal; c. second switch means for connecting at least the selected second electrode to a reference voltage responsive to a second switch closure signal; d. means for applying a first switch closure signal to the first switch means responsive to an erase select signal; e. means responsive to the second erase select signal for applying to the selected second electrode a conditioning pulse which overlaps the period of connection of the selected first electrode to the reference voltage and which produces conduction causing reversal in polarity of the wall charge in the dielectric adjacent at least the selected gas volume; f. means responsive to an erase select signal for applying a second switch closure signal following the conditioning pulse, to the second switch means; and g. means responsive to the first erase select signal for applying to the selected first electrode an erase pulse whose duration is greater than that of a sustain pulse and whose voltage for a substantial part of its duration is substantially less than peak sustain pulse voltage, said erase pulse overlapping the period of connection of the second electrode to the reference voltage and causing conduction reducing below that necessary to permit sustaining of light emission, the wall charge in the dielectric adjacent the selected gas volume.