INCANDESCENT LAMP HAVING INFRARED REFLECTING FILM

摘要

PROBLEM TO BE SOLVED: To resolve a problem hard to solve easily because of generation of reflected light in a visible light range to deteriorate a color rendering property by composing multiple kinds of reflecting films with only conventional SW reflecting films to increase the feedback amount to an infrared filament and thereby to further improve the luminous efficiency of this kind of incandescent lamp. SOLUTION: This incandescent lamp 1 having an infrared reflecting film has a structure wherein the infrared reflecting film is so formed that an infrared-ray having a wavelength in the range of 750-1300 nm is reflected by at least one kind of multiple layers of an SW type reflecting film 4 composed by alternately laminating multiple low refraction-index films L and high refraction-index films H each having a film thickness of 1/4 of a desired wavelength, and an infrared-ray having a wavelength in the range more than 1300 nm is reflected by at least one kind of multiple layers of a five-layer type reflecting film 5 in a five-layer period form of which film thicknesses are defined respectively for a desired wavelength, so that reflection is not generated in a visible light range even if infrared-rays in a wide wavelength range are fed back to a filament.