Abstract This invention relates to an incandescent lamp bulb comprising a visible light transmitting and infra-red 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 ½ x 0.21 to <sup>1</sup>/<sub>2</sub> 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.
An incandescent lamp bulb comprising a visible light transmitting and infrared ray reflecting film composed of a lamination of alternate high and low refractive index layers and formed on at least either one of the inside and outside of a tubular, transparent bulb, a filament made of tungsten wire centrally disposed along the longitudinal axis of said bulb, wherein the optical film thickness of any one of the high refractive 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.
Claim 2
Dependent Claim
130 words
An incandescent lamp bulb comprising a visible light transmitting and infrared ray reflecting film composed of a lamination of alternate high and low refractive index layers and formed on at least either one of the inside and outside of a tubular, transparent bulb, a filament made of tungsten wire centrally disposed along the longitudinal axis of said bulb, wherein the optical film thickness of any one of the high refractive 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.
Claim 3
Dependent Claim
50 words
An incandescent lamp bulb according to claim 1, wherein said at least one low refractive index layer ranging in the optical film thickness from 2 x 0.21 to 2 x 0.31 p of said low refractive index layers is disposed relatively on the lower layer side of the multilayer film.
Claim 4
Dependent Claim
44 words
An incandescent lamp bulb according to claim 1, wherein said at least one low refractive index layer ranging in the optical film thickness from 2 x 0.21 to 2 x 0.31 p is disposed relatively on the upper layer side of the multilayer film.
Claim 5
Dependent Claim
49 words
An incandescent lamp bulb according to claim 1, wherein said at least one low refractive index layer ranging in the optical film thickness from 2 x 0.21 to 2 x 0.31 µ is disposed relatively on the lower layer side and the upper layer side of the multilayer film.
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