Abstract: Erase and "shifting write" pulses are applied across pairs of adjacent sites in each row of an ac plasma panel in a predetermined sequence. The shifting write pulse occurs during the conventional erase time period and its magnitude and duration are such that it will switch an OFF site on the ON state only if that site has received spread wall charge from an adjacent ON site. In addition, a scan erase pulse is used to temporarily lower the wall charge of certain ON sites when shifting is to be initiated, thereby preventing possible backshifting.

Abstract: 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.

Abstract: Write pulses are applied to the cells of a plasma display panel to repetitively establish the cells in respective temporary ON states in which the wall voltage stored at each cell decays with each applied sustain pulse. The average number of sustain cycles over which a particular cell remains in the temporary ON state, and thus its perceived brightness, is controlled by controlling the intra-sustain-cycle time occurrence of the write pulses applied thereto.

Abstract: The state of a plasma or similar display cell is inverted by a two-pulse sequence comprising an inverting write pulse followed by an inverting erase pulse. The inverting write pulse switches a cell ON if it was OFF, while the inverting erase pulse switches the cell OFF if it was ON. The inverting write pulse is adapted to cause a gradual, rather than an immediate, wall voltage build-up so that the inverting erase pulse is of insufficient magnitude to turn a cell OFF if it was turned on by the inverting write pulse.

Abstract: A matrix array of liquid crystal cells is defined by overlapping pluralities of row and column conductors confining a layer of liquid crystal material. Each row conductor is connected through a bilateral threshold switch to one side of a source of periodic alternating polarity sustain signals, and the column conductors are sequentially connected to the other side of the source. When an initial charge is deposited on selected ones of the capacitors forming the liquid crystal cells, the series combination of the resulting stored voltage and the sustain signals is sufficient to exceed the threshold of the bilateral switch, thereby connecting the previously selected cells to the source of alternating source on a column-by-column basis so as to recharge the previously selected cells. Since charged cells exhibit differing electro-optic properties from uncharged cells, a graphical image may be generated and stored without the need for information-bearing refresh signals.

Abstract: An a-c plasma display panel including apparatus for driving the keep-alive cell sustain signal circuits in a non-fixed relation with address pulses. By constraining the keep-alive sustain signal to selectively lag the addressing signal by an amount dependent on the address of a cell being addressed it is possible to refine the control over voltage margins afforded by dynamic keep-alive while simplifying the circuitry required to produce it.

Abstract: A planar plasma discharge shift register includes a plurality of electrodes of a first polarity and a unitary electrode of the opposite polarity. Multi-phase clock signals applied in succession to each of the pluralities of electrodes cause a plasma discharge, once initiated, to propagate in controlled fashion along a path prescribed by the location of the electrodes. By suitable shaping of the electrodes, and through a judicious choice of clock signals, it is possible to propagate a gaseous discharge bi-directionally.

Abstract: An a-c plasma display panel including apparatus for driving the keep-alive cell sustain signal circuits in a non-fixed relation with address pulses. By constraining the keep-alive cells to be sustained in a time relation dependent on the address of a cell being addressed it is possible to increase the margins for the address signals and, in general, permit a reduction in magnitude of such address signals.

Abstract: An enhanced light pen capability is provided in plasma display panels by applying specially timed write and erase pulses in a scanning manner over the panel, the pulses being shaped and positioned relative to the normal sustain pulse sequence in such manner that a light pulse is emitted upon the resulting momentary write or erase which is detected by a light pen of standard design while avoiding any but transient modification to the state of the cell wall capacitance. The scanned write pulses advantageously assume the form of modified write pulses with shortened duration and less abrupt terminations than is usual. Dynamic keep-alive circuitry for applying location-dependent priming enhances the operating margins to permit reliable, constant-voltage write and erase signals for all cell locations.

Abstract: A two-dimensional planar display device includes a plurality of plasma discharge shift registers positioned along rows of a display matrix. An additional shift register positioned along one column at the edge of the display matrix causes a plasma discharge to be transferred to the beginning of each successive row shift register. By transferring a discharge along each position in successive rows, a discharge is propagated in a two-dimensional scanned manner over the face of the display matrix. By suitably modifying the level of the propagating signals in accordance with an applied video signal, the brightness of the scanned discharge is modulated to produce a variable gray scale image.

Abstract: A light pen tracking system and method particularly adapted for use with a plasma panel in which a first plurality of display sites on a display device are sequentially excited in such manner as to generate a signal which may be detected by a light pen. Upon detection of a first light signal, a second set of display sites centered at a location identified by the first signal and having smaller area than the first scanned area is then scanned. Because a relatively small area is scanned in the second scanning mode, and because the center of this smaller area has been localized by the previous signal detection, it is possible to more closely track rapid movements of a light pen on a display surface.