Plasmatron

The Plasmatron, or technically plasma addressed liquid crystal (PALC), is a color television display technology developed by Tektronix and Sony in the 1990s. PALC displays combine rows formed from liquid crystals with columns formed from plasma cells, the latter replacing the transistorized switching in a conventional LCD. Although PALC was successfully developed, thin-film transistor based LCD devices were improved which offset PALC's advantages. PALC development has been largely abandoned since the early 2000s. History PALC was originally developed by Thomas Buzak, who worked at Tektronix in the U.S. Through the late 1980s and early 1990s he developed and patented a number of concepts that used plasma to provide a switching element for a variety of uses. When the project he was working on was canceled, he turned his attention to using the plasma elements as LCD switches, and the PALC system was born. In 1993 Tektronix licensed the technology to Sony, and together they started development of the Plasmatron televisions. In October 1996 Sony entered a three-year arrangement with Sharp Electronics to share development, with Sharp's role being to help improve the effective display angles. In July 1997 the group was joined by Philips Electronics to improve the resolution of the devices, reduce power consumption and increase brightness. Sony and Sharp both produced high-definition television prototypes using the PALC technology, but these never made it to production. PALC was offset by the rapid introduction of thin-film transistors, which allowed individual cells of the LCD to be addressed directly. A grid of rows and columns allows the transistors to be turned on or off just like the plasma cells, but without the need for high voltages or resetting pulse. At first these devices were difficult to produce, but as processes improved the printing methods developed from the semiconductor industry replaced the mechanical complexity of the PALC cell. PALC is no longer being actively developed.