International Business Machines Corporation

Tony N Criscimagna

Michael Joseph Steinmetz

Albert O Piston

Harry S Hoffman, Jr

William R Knecht

William J Martin

James B Trushell

James C Greeson, Jr

Thomas J Milich

John R Beidl

An a.c. Plasma Display Panel is operated in a scanning mode using a conventional video data stream such as that applied to a cathode ray tube display terminal. A full line write followed by a selective erase technique is employed for image generation on a line by line basis. By eliminating the non-selective write signal used in normal plasma display operation, the duration of the sustain signal is substantially decreased and the write, erase and sustain functions are provided at a nominal 40KC rate.

Video mode plasma panel display

Operation of an AC plasma display panel requires the three control operations of write, erase, and sustain. Sustain, write and erase signals are stored in a plurality of sections in a storage device and the sections are selectively accessed according to the specific operation to be provided to the plasma panel display. The control signals stored within a given sequence are selected so that no dimming occurs during write and erase operations. A brightness control is provided to modulate the average repetition rate of signals applied to the plasma display panel. In this manner, a plurality of flicker-free brightness levels may be chosen.

Repetition rate compensation and mixing in a plasma panel

An A.C. Plasma Display Panel is operated in a video mode using the same signal train as applied to a conventional cathode ray tube terminal. For character generation, a selective erase technique is employed in which all cells in a raster line are discharged and then selectively erased in accordance with the video data to be displayed. To facilitate the erase operation, a line of cells in close proximity to the scan line being selectively erased is employed to provide adequate and uniform priming for the erase operation, and is synchronized to maintain its position with respect to the line being erased. A short plasma erase signal is utilized to fit within the scan rate of the display. The invention is also applicable to character generation in block or multi-line mode.

Video mode plasma display

Low cost apparatus for a gas display panel is operated by a method to provide reliable write, sustain, and erase operations. For sustain operations a first square wave train is applied to all horizontal lines of the gas display panel simultaneously as a second square wave train, displaced 90.degree. from the first square wave train is applied to all vertical lines. For a write operation the frequency of the first and second square wave trains is reduced, and a pulse is superimposed or algebraically added to the sustain signals which results in a composite signal. The superimposed signal (a) increases the potential on a selected horizontal line, (b) decreases the potential on the remaining horizontal lines, (c) decreases the potential on a selected vertical line, and (d) inceases the potential on the remaining vertical lines. The selected cell receives an increased potential difference sufficient to equal or exceed the ignition potential after all of the remaining cells receive a sustain potential which ignites all cells which were previously ignited. The algebraically added pulses cancel out the effect of each other across the half selected cells and the non selected cells. For an erase operation a given signal of constant magnitude and polarity is applied to all horizontal lines and all vertical lines, and a pulse is algebraically added on the given signal which (a) increases the potential on a selected horizontal line, (b) decreases the potential on the non selected horizontal lines, (c) decreases the potential on a selected vertical line, and (d) increases the potential on the non selected vertical lines whereby no gas cell in the gas panel receives a potential difference sufficient to equal or exceed the sustain level. However, the selected gas cell, and only this gas cell, receives a potential difference having a polarity opposite to that of the last sustain signal and an amplitude that is just barely sufficient to fire the cell, and this is effective in reducing the charge sometimes referred to as the wall charge, across the selected gas cell substantially to zero. After a suitable time delay, referred to as dead time, the wall charge across the selected gas cell is reduced to zero, and the selected gas cell thus is returned to the extinguished state. A sustain operation then takes place which reignites all gas cells previously ignited before the erase operation except the selected erased cell. The algebraically added pulses cancel out the effect of each other across the half selected cells and the non selected cells.

Method and apparatus for gas display panel

A system for providing sustain, write and erase operations in an AC plasma gas display panel in which selstain circuits are created by integrating the sustain and selection functions. Each selstain circuit is deposited on a single integrate circuit. This circuit is fabricated with low voltage integrated circuit technology. In addition, the sustain signal is floated on the write/erase signal.

'Selstain' integrated circuitry

A plasma panel arrangement for storing, displaying and selectively shifting information from one place therein to another includes a panel filled with an illuminable gas, and horizontal and vertical parallel conductor arrays disposed on opposite sides of the panel, the coordinate intersections of the conductors defining gaseous discharge cells. The vertical conductors are sequentially driven by a multi-phase drive system, and the panel includes a plurality of data lines for entering information. The data as entered is sequentially shifted left or right in a horizontal direction in a single line display. In a multi-row display, the system provides left or right shifting of one character row while holding the display of the other character rows. The instant invention makes the plasma shift technology competitive in speed to X-Y matrix addressed panels, but at a much reduced circuit cost.

Multiple data line shift gas panel assembly

In driving gas panel or plasma display devices, characters are generated on the panel display as a sequence of dots by applying appropriate drive signals to selected orthogonal conductors, each conductor requiring an associated driver. In a low character count small plasma display such as a single row display utilizing a 5.times.7 dot character matrix, a significant load is presented to the horizontal drivers, while a substantial number of drivers are required to drive the vertical axis. To improve the load distribution and increase the drive efficiency of such a system, the horizontal conductors are divided into four distinct groups, with associated drivers, while a single set of vertical conductors is used to drive the vertical conductors, which are positioned to intersect each of the groups of horizontal conductors. The individual load requirements as well as the number of vertical drivers are reduced by a factor of four at a nominal increase in the number of horizontal drivers, thereby providing a significant cost reduction. The specific wiring pattern used to achieve this result on a plasma display device is disclosed herein.

Reduced connection for 22 character gas panel

Erase waveforms effecting improved erase action are provided for a gas panel of the type in which light emitting cells are formed in an ionizable medium at the crossover point of a set of horizontally and vertically extending insulated wires. The erase waveforms include a burst of bipolar pairs of pulses, each pair comprising a low amplitude wide duration erase pulse followed by an opposite polarity narrowed sustain pulse. The burst of pulse pairs being applied during the time frame of a normal sustain operation.

Bilateral selective burst erase system

A circuit for supplying sustain voltage pulses to the orthogonal conductors of a gas display panel including voltage sensors to sense any change in sustain voltage amplitude with aging of the circuits and a voltage controlled oscillator to shift the operating frequency of sustain pulses as the amplitude changes. In that manner, the operating point of sustain voltage vs. frequency is shifted to take advantage of the slope in a graphical representation of sustain voltage margin to allow for shifting of the margin due to panel aging.

Voltage controlled sustain frequency in a gas display panel

An improved light pen is provided for a gas display panel of the type in which an alternating polarity sustain voltage produces a succession of brief light flashes in a matrix of light emitting cells. The timing for the sustain voltage is disturbed along a selected coordinate of the matrix. The coordinate of a light pen is identified when light with this disturbed timing is detected by the pen. Circuits for disturbing the sustain voltage of an individual cell of the matrix are also disclosed.

Gas display panel with light pen

A system for addressing and controlling a gaseous discharge display or memory device is adapted for intercommunication between a processor or controller, control logic and panel driving circuits in a gaseous discharge display system. By application of write and systain signals to selected transverse conductors disposed on opposite sides of a gas filled panel, selected sites positioned at conductor intersections are discharged, emitting light, and the resultant display maintained by the wall charge phenomenon and sustain signals. Logic circuits and panel drive circuits are electrically floated on the sustain voltage for the panel whereby the sustain signal provides a common reference, thus permitting the use of low voltage circuits particularly adapted to integrated circuit packaging. Coupling means are employed to isolate the signals from the logic control from the panel selection, control and drive circuits, permitting control of the high voltage panel operation by low level coded signals. By utilizing a pulsed supply for line drivers rather than a fixed power supply, power and heat dissipation are further reduced, thereby facilitating integrated circuit packaging. The preferred embodiment of the present invention is adapted to write, sustain and erase a gaseous discharge panel.

Floating addressing system for gas panel

A modular control system is provided for a gas panel of the type having an array of row wires and column wires that form light emitting cells at their crossover points. A row counter and a column counter provide selection signals for entering characters sequentially on the panel. The counters provide borrow and carry signals to components that control the display. Thus, the control operates without regard to the actual size of the display and provides a modular construction for displays of various sizes.

Alphanumeric gas display panel with modular control

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.

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Woodstock, NY, United States of America

Tony N Criscimagna