A simple technique for obtaining variable intensity in AC plasma display panels

A technique for obtaining gray scale in ac plasma display panels is described which uses only one discharge site per resolution element, does not require extensive electronic memory and provides a continuous, broad intensity range. A maintain voltage is applied to all elements of the display panel whose magnitude is somewhat less than the lower limit of the bistable region in which ac plasma panels are normally operated. The application of a trigger voltage initiates a sequence of discharges of diminishing intensity which continues for a substantial number of cycles before dying out. The number of cycles that the discharge sequence persists depends on the magnitude and duration of the addressing trigger voltage. If the panel is operated in a refresh mode, the average brightness of the light emitted may be controlled by varying the magnitude of the trigger pulse voltage. The gray scale method may be used to address a matrix display panel with video information using line-at-a-time addressing.