The illuminants used in projectors are transitioning from ultra-high-pressure mercury lamps to solid-state illuminants (LEDs and LDs). Ultra-high-pressure mercury lamps saw use in projectors for their ability to create extremely high luminance from a very small light-emitting area of about 1 mm2, enabling efficient use of emitted light. However, lamp lifespan mandated replacement every hour and is accompanied with problems such as flicker and reduced illuminance occurring toward the end of the lifespan.

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The replacement of these lamps with LED and LD illuminants has resolved those shortcomings, but at a higher cost. To constrain cost and to secure the necessary amount of light, fluorescent wheels with a disc-shaped wavelength conversion element and blue LEDs/LDs are used. However, because the phosphors arranged on the disc are solidified powder phosphors, scattering is significant and usage is not efficient. By contrast, the use of our highly transparent quantum-dot silica-based inorganic material composite enables the efficient extraction of light and the configuration of economic systems based on silica (glass).