Light-Controllable Spot Liminaires Using a Liquid Crystal Light Shutter and a High-Intensity Discharge Lamp
New types of light-controllable luminaires using a metal halide lamp or a xenon lamp with a liquid crystal light shutter have been developed and demonstrated for spot or beam spot lighting of television program production. We fabricated a novel liquid crystal light shutter using a heat-resistant composite film of polymer and liquid crystal materials with a wide range of operating temperatures up to 150°C. The light shutter can modulate a strong luminous flux from the high-intensity discharge lamps, instead of a conventional mechanical shutter which has problems such as generating acoustic noise and being slow and heavy. The light modulation of the light shutter is based on a light scattering effect and the degree of scattering is controlled by the voltage applied to the shutter. It exhibits attractive features such as high transmittance, high-speed response, and high extinction ratio. The luminous intensity of an object could be varied continuously using the luminaries with the shutter, and the chromaticity deviation was drastically decreased by driving it with pulse width modulation.