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Light valve using suspended particles was invented first by Edwin H. Land. But it could not be made tolarge area because it was a liquid cell containing a suspension of the particles between both transparentconductive layers. For several tens years, so many trials have been to make a large size of light valve. Recently we could make the light valve of large size which is film type by phase separation and/or emulsification methods. In this paper, we are introduce the light valve film made by HGI.Keywords: light valve film, suspended particles device(SPD), phase separation, solvent evaporation 1. INTRODUCTION A Light valve was invented and patented by Edwin H. Land'. Land's light valve is a cell comprising a suspension of small particles between two conductive substrates, with at least one of them beingtransparent. In the absence of an applied electric field, the particles in the liquid suspension exhibit random Brownian motion, and hence a beam of light passing into the cell is reflected, transmitted orabsorbed depending upon the nature and concentration of the particles and the intensity of light. Howeverwhen an electric field is applied through the suspension, the particles become aligned parallel to theelectric field, and most of the light can pass through the cell.But due to the difficulties with these early light valves including particle settling, particle clustering,color change by heat, reduction of off-state optical density, and degradation by ultraviolet(UV) light |
