Browse Prior Art Database

High Level Driver for Gas Discharge Panel

IP.com Disclosure Number: IPCOM000080798D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kleen, BG: AUTHOR

Abstract

In conventional gaseous discharge display panel technology, relatively complex waveforms may be required to generate either write or erase sequences. One preferred method is the use of a sustain pedestal to which write or erase pulses may be added. In gas panel operation, it is essential to prevent crosstalk, i.e., the firing of nonselected cells by a half-select signal, particularly when adjacent selected cells are fired.

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High Level Driver for Gas Discharge Panel

In conventional gaseous discharge display panel technology, relatively complex waveforms may be required to generate either write or erase sequences. One preferred method is the use of a sustain pedestal to which write or erase pulses may be added. In gas panel operation, it is essential to prevent crosstalk, i.e., the firing of nonselected cells by a half-select signal, particularly when adjacent selected cells are fired.

One method used to avoid this problem is to apply a 180 degrees out-of- phase deselect voltage to all nonselected cells when a select voltage is applied to a selected cell so that the half-select voltages in the nonselected cells are effectively cancelled. The operation of a gas panel requires that an alternating sustain signal, at a nominal frequency of 40-100 KHz, be continuously applied to all cells to maintain the display, once specific cells are selected. However, the drive transformers must be so connected that the sustain currents are cancelled during the write or erase sequence.

Referring to the drawing, a transformer 1 having a primary winding 3 has a dual secondary comprising windings 5 and 7, which are bifilar wound for close magnetic coupling. For normal sustain operation, transistor switches 9 and 11 are closed, and sustain signals +Vs and -Vs are applied to secondary windings 5 and 7. This causes currents to flow alternately from +Vs to transformer center tap 13, through the lower half of the winding 5, diode 15, the panel cell shown as capacitor 17, the vertical drive line 19, transistor 11 i...