The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 08, 1992
Filed:
Jun. 15, 1990
Akira Kawakatsu, Yokohama, JP;
Toshiba Lighting & Technology Corporation, Tokyo, JP;
Abstract
Four different optical interference films are formed on the outer surface of an incandescent lamp to achieve good color rendering properties at a high color temperature. A first film formed on the lamp includes high and low refractive index layers alternately stacked so that the total number of layers is n (where n is odd number greater than 5) and the optical thickness thereof is 0.12.about.0.17 .mu.m. A second film formed on the first film has the low refractive index layer and the optical thickness of 0.132.about.0.2125 .mu.m, which is calculated by the equation (K+1).times.d/2, wherein K is 1.2.about.1.5 and d is the optical thickness of each refractive index layer of the first film. A third film formed on the second film has at least a high refractive index layer. The total number of refractive index layers of the third film is an odd number of 1.about.(n-4) and the optical thickness of each refractive index layer thereof is 0.144.about.0.255 .mu.m, which is calculated by the expression (K.times.d). A fourth film includes the low refractive index layer having the optical thickness of 0.0720.about.0.1275 .mu.m, which is calculated by the expression (K .times.d/2).