Driver Module Sharing Scheme
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
AbstractFor large size gas panel displays, it is desirable to be able to reduce the number of line drivers required, as they constitute a major part of the expense of the display. This article proposes a method of accomplishing this objective by having a single line driver connected to several panel lines simultaneously.
Driver Module Sharing Scheme
For large size gas panel displays, it is desirable to be able to reduce the number of line drivers required, as they constitute a major part of the expense of the display. This article proposes a method of accomplishing this objective by having a single line driver connected to several panel lines simultaneously.
The basic operation of this approach is best understood by examining the elemental case of Fig. 1 which illustrates a very simple gas panel with only two cells, A and B Shown in Fig. 2 are the waveforms which are to be applied to the various panel lines. The waveforms applied to the horizontal line designated H and to the vertical lines designated Vw forming the cells A and B are similar to those conventionally used in gas panel displays. The other vertical lines which form pockets around the selection lines use Vp drive signals to force cells A and B to perform differently even though they are driven with common voltages.
Referring back to Fig. 1, the left pocket lines are grounded and thus appear to cell A as adjacent deselected vertical lines. The right pocket, however, is pulsed negative at the same time as the positive write pulse is applied to the cells, raising the amplitude of the write pulse required to discharge cell B. This effect can be shown to be due to the spreading of the electromagnetic fields resulting in cross talk between adjacent lines.
Since the minimum write voltage required to ignite cell B has been raised above that for A by the action of the pocket pulse applied around B, it is possible to choose a write voltage which will discharge cell A, but be insufficient to discharge cell B. The installation of a switch to allow the pocket lines for cells A and B to be connected to either ground or the pocket pulser, as desired, would then permit either cell to be written selectively. By this addition of a pocketing pulse, it has become possible to have the single line driver of Fig. 1 selectively write either cell A or B. Although the embodiment in Fig. 1 selects lines from the top, the technique can be extended to allow either top or bottom lines to be the select lines, with the other set used to form the pocket lines. To form the pockets in Fig. 1, one need only to short together sections of lines on one apron or line termination, or drive them individually from a common source.
One practical embodiment of this concept es applied to a small gas panel is illustrated in Fig. 3, it being understood, however, that the approach is more generally applicable. Fig. 3 shows a small panel of 36 vertical lines being driven by two driver modules of 6 lines each, each output driving 3 panel lines. Each of these conventional driver modules has a DPDT switch associated with it, allowing the module to function either as a selection module or as a connection to the pocket pulser. Assume that the upper module switch 12 is in the "up" position so that the module 10 will receive the Vw write pul...