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Full color liquid crystal (LC) displays with 5 inch diagonals are readily available today, and manufacturers are ramping up production of 10 inch full color displays for laptop computers. These displays require an integrated thin film transistor (TFT) as well as a capacitor to capture and store analog data voltage for a sixtieth of a second at each display element. For large displays there can be a million or so of these switching and data storage elements that comprise, in effect, a megasample analog memory. Fabricating such arrays is proving to be a formidable task. The concept for replacing the array of integrated TFTs with functionally identical plasma switches to address LC displays was first disclosed in the May, 1990. These switches consist of a channel of ionized gas that can be turned on and off quickly and that are capacitively coupled to the storage elements of the display. To achieve rapid data capture as well as fast turn-off of the columns of ionized gas it appears that at least one component of the gas must have a low atomic weight. To ensure long term stability, nonreactive gases are needed. Helium is an obvious choice since it is light and nonreactive, and furthermore, only a low level of visible light is generated when it is ionized in the channels. Unfortunately helium permeates through the glass enveloped of a liquid crystal display faster than any other gas. Containing it for the five to ten year life of a display is a challenge, and progress toward meeting that challenge is discussed here after a brief review of the plasma addressing (PA) concept.
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