Negative grid addressing for polymer-dispersed liquid-crystal devices


  • Steven McKiel McMaster University


Variable opacity smart glass technologies, particularly electrically switchable polymer-dispersed liquid-crystals (PDLC), are emerging as a field with many potential applications. This article lays out an algorithm for addressing a grid of PDLC tiles that can be used to locally block out any given location. This has potential for use in a new form of “smart” windshield. Due to the nature of the liquid crystal dipoles that are found within PDLC films, a negative addressing method that exploits the switching speed discrepancy of PDLC is discussed to circumvent the issue of inadvertently blocking out complete rows and columns on the grid. The process by which this is applied is further extended to use of more complicated algorithms; namely, 4-tile squares, 2 similar location tiles sharing an x or y coordinate, and 2 location tiles that are unrelated in location. The algorithms are tested at slow speed using a basic light-emitting diode (LED) setup and at full driving speed as measured by an oscilloscope. An effective manual method of testing the PDLC switching algorithm is also illustrated. Finally, limitations of the methods discussed and further ideas for module improvements were also outlined.