Comparison of Thin-Film and Wire-Wound Heaters for Transparent Applications

Warming an LCD display, glass plate or test chamber window to enhance visibility creates difficult design problems. Flexible heaters with silicone rubber or polyimide insulation block light, making viewing through the material impossible. Heating only around the edges with a larger cartridge style heater or opaque flat heater may not provide enough heat to warm the entire surface, or may lead to temperature gradients that can fracture glass. The solution is a clear heating element that can provide heat to the entire surface. Two types of clear heaters are commonly used - thin-film Indium Tin Oxide (ITO) and optically clear polyester wire-wound. This study compares how the intrinsic qualities of each of these heater types can influence visibility.