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US 6,661,164 B2Granted
Incandescent lamp
AssigneePatent-Treund-Gesellschaft F. Elektrische Gluehlampen mbH
InventorsJuergen Ruemmelin, Reinhard Schaefer
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Abstract
The invention relates to an incandescent lamp whose lamp vessel (20) has an interference filter (30) with locally differing layer thickness for producing red light. The interference filter (30) has a second absorber layer and additional layers of low optical refraction and high optical refraction for reducing its transmission in the violet, blue and green spectral regions.
Claims10
An incandescent lamp comprising:
- a transparent, essentially rotationally symmetrical lamp vessel (20), an incandescent filament surrounded by the lamp vessel (20), and an interference filter (30) which is arranged on the lamp vessel (20) and designed as an edge filter,
- the interference filter (30) having layers of low optical refraction and high optical refraction for setting the edge of the interference filter (30) in the red spectral region,
- the layer thicknesses of the layers of low optical refraction and high optical refraction differing locally as a function of the angle of incidence of the light emitted by the incandescent filament and impinging on the interference filter, and the interference filter (30) having absorber layers of different material than those of the layers of low optical refraction and high optical refraction for absorbing blue and violet light,
- wherein the interference filter has at least two of these absorber layers of iron oxide with, in each case, an intermediate layer of low optical refraction arranged therebetween, and additional layers of low optical refraction and high optical refraction for further suppressing light from the violet and blue spectral regions.
1 more element
Dependencies are inferred from the claim text.