An improved write circuit for a gas panel produces a sequence of alternating polarity write pulses that are superimposed on a sequence of half cycle pulses of the sustain waveform. Thus the accumulation of charges on the walls of a light-emmitting cell that is required for a write operation is produced by a sequence of write pulses, and each write pulse is lower in amplitude than is required for a single write pulse. The write pulses are progressively shifted ahead in phase to further improve the operation.
An improvement to sustain drive circuitry for an AC plasma display panel wherein the sustainer signal applied to panel electrodes is simplified to comprise a sequential series of square waves. The actions of writing, selectively erasing and bulk erasing of light emissions in cells of the plasma panel are also performed by combinations of square wave signals generated in sustainer and driver circuits of the device. A combination of integrated circuits comprise both the X and Y axis drivers with the Y axis drivers also including an internally generated Y axis sustain signal onto which Y axis write or erase signals are impressed. The prior art requirement of floating supply voltages is removed and the number of supply voltages is decreased such that all driver and sustainer circuits utilize a common power source, with a maximum of three source voltage levels for operation of all sustainers, drivers, address inputs and logic and timing control of the circuitry. The X axis sustainer may alternatively be comprised of a Mosfet circuit herein disclosed, included two high voltage high current Mosfet transistors connected in a totem pole fashion and operated in a manner which avoids simultaneous conduction of both transistors, thus reducing heat dissipation problems.
A time-voltage multiplexing system for addressing a particular cell or location on a gas discharge plasma panel in which a group of panel electrodes are charged to the cell voltage firing level but only one electrode of the group is allowed to remain charged for a time duration sufficient for selective discharging of the desired cell. A multiple secondary transformer embodiment incorporating the time-voltage multiplexing addressing system. A method and apparatus for increasing the usable range of sustaining signals for plasma panels by applying a narrow width boost pulse to the panel within a selected time immediately after the initiated sustaining discharge, including means for varying the boost pulse amplitude, width and position with respect to the sustaining discharge so that the usable sustaining signal range can be optimized for a particular plasma panel.
An enhanced light pen capability for plasma display panels is provided by applying specially timed scan write and scan erase pulses to the cells of the panel, the pulses being shaped and positioned relative to the normal sustain pulse sequence such that a light pulse is emitted, while avoiding any but transient modification of the cell wall voltage. The light pulse is detected by a light pen of standard design. Dynamic keep-alive circuitry for applying location-dependent priming enhances the operating margins.