Plasma panel pre-write conditioning apparatus

In a gas discharge display matrix of the type having at least one chamber containing ionizable gas and formed of a dielectric having at least one first electrode extending along a first side of the chamber and spaced apart from any other first electrodes and a plurality of spaced apart second electrodes on a second side of the chamber, 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 for which

• i. a write pulse between a first and a second electrode of voltage at least equal to a minimum firing value causes firing of the gas volume between these electrodes and creation of substantial wall charge adjacent thereto, if no adjacent wall charge is present,
• ii. a sustain pulse between a first and a second electrode of voltage in a range between preselected minimum and maximum sustain values causes firing of the gas volume between these electrodes and creation of a substantial wall charge adjacent thereto if substantial wall charge of polarity discharged by the sustain pulse is present, and insures not firing otherwise, and
• iii. an erase pulse between a first and a second electrode of voltage between preselected maximum and minimum erase voltages and of polarity discharging wall charge adjacent the gas volumes between these electrodes created by a previous sustain pulse, insures removal of substantially all of said wall charge, and
• means for applying to the electrodes said write, sustain and erase pulses in the manner indicated;
• improved apparatus for making free electrons available to selected gas volumes for increasing reliability in firing by a write pulse, and comprising:
• a. timing means for receiving a write select signal specifying at least one first electrode and for issuing responsive thereto at least one timing signal occuring prior to the associated write pulses, and following a selected sustain pulse having preselected first polarity;
• and
• b. means receiving each timing signal and write select signal for applying between the selected first electrode and the plurality of second electrodes first and second dual-on-state biasing pulses, and a dual-on-state firing pulse all superimposed on each other where overlapped;
• i. each of said first biasing pulses starting responsive to the first timing signal and having a predetermined duration, reaching a predetermined magnitude appreciably different from zero and no greater than the maximum sustain voltage and having the same polarity, measured with respect to the electrodes involved, as was created by the selected sustain pulse;
• ii. each of said second biasing pulses having polarity opposite that of the first biasing pulse, starting after the first biasing pulse and having a predetermined duration, and a predetermined magnitude substantially different from zero and no greater than the minimum sustain voltage;
• and
• iii. each of said firing pulses having polarity opposite that of the first biasing pulse, having magnitude less than the minimum write voltage and sufficient to cause conduction, when superimposed on the first biasing pulse, by each gas volume between the plurality of second electrodes and the selected first electrode which did not conduct during the most recent sustain pulse, but insufficient to cause conduction by the gas volumes adjacent the selected first electrode which did conduct at that time, and starting and finishing during the first and second biasing pulses respectively.