Light-valve technologies for high-definition television projection displays

Light-valve projection offers high resolution with large image areas and high brightness, and it thus appears to be most suitable for HDTV displays. The increasing availability of active-matrix-addressed liquid-crystal light-valve projectors for standard television, and the continuing dominance of 'classical' electron-beam-addressed light-valve projectors for the most demanding professional applications, are the starting points of a survey on the state of the art. After the two groups of light-valve projectors have been briefly reviewed, the major light-valve technologies are explained in some detail. Transmissive and reflective liquid-crystal light valves with various types of addressing are described first; the trend toward active-matrix addressing and high resolution is demonstrated. Commercial light-valve projectors with electrooptic and oil-film control layers are briefly introduced, and alternative technologies, such as metallized viscoelastic layers, deformable micromechanical mirrors, and polymer-encapsulated liquid crystals, are discussed. The author's research on deformable viscoelastic light-valve control layers for use in schlieren optical systems and on Si-MOSFET active matrices for addressing these is reported in some detail. The deformation behaviour of thin metallized elastomer layers has been analysed. Sample MOSFET active matrices with picture-element densities suitable for HDTV have been designed and fabricated. A full-colour schlieren optical projection system is briefly described.