Multiple states and variable intensity in the plasma display panel

The plasma display panel, in its usual mode, retains information in the form of wall charges that determine whether or not a sequence of discharges will be maintained at a given cell. These discharges are stable in the sense that a perturbation in wall voltage at a particular discharge will damp out over the succeeding discharges. Recent work has shown that a cell in a plasma display panel can exist in one of several states, each with a unique set of wall voltages and each with a unique average intensity. As with the bistable case, each state is stable in the sense that perturbations damp out. Three states have been achieved simultaneously, with brightnesses that can be characterized as bright, medium, and dim. Within the constraints of a simple theoretical model, the conditions for stability can be stated in terms of the products of the slopes of charge transfer curves. This technique for achieving variable intensity retains the advantage, inherent in the plasma display technique, that the information, once imparted to the display, is retained as long as the sustaining signal is applied to the entire panel.