Incandescent lamp with bulb having ir reflecting film

Abstract From the Canadian patent

This invention relates to an incandescent lamp bulb comprising a visible light transmitting and infrared ray reflecting film formed on at least either one of the inside and outside of a tubular transparent, bulb, said film being composed of a lamination of alternate high and low refractive index layers wherein, the optical film thickness of any one of the high reflective index layers ranges from 0.21 to 0.31 µ that of the topmost low refractive index layer ranges from 1/2 x 0.21 to 1/2 x 0.31 µ, that of at least one low refractive index layer ranges from 2 x 0.21 to 2 x 0.31 µ, and that of any remainder low refractive index layer ranges from 0.21 to 0.31 µ.