Electric lamp and discharge devices – With temperature modifier – Double wall – jacket or casing for envelope
Reexamination Certificate
1998-10-09
2001-05-01
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With temperature modifier
Double wall, jacket or casing for envelope
C313S017000, C313S634000, C313S292000
Reexamination Certificate
active
06225731
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the field of glass halogen lamps and, more particularly, to a glass halogen lamp with an internally mounted shroud for reflecting infrared radiation back to the lamp filament.
Thin film optical interference coatings, known as interference filters, including alternating coating layers of two or more materials having different refractive indices, are used in the illumination field to selectively reflect and/or transmit light of different wavelengths. Interference coatings can be used to transmit various portions of the electromagnetic spectrum, such as visible light, while reflecting other portions of the electromagnetic spectrum, such as ultraviolet or infrared radiation. These interference coatings are used in the lamp industry to coat Reflectors and/or lamp envelopes to achieve desirable illuminance patterns and to filter out undesirable energy.
Thin film optical coatings have been used on lamp enclosures to improve the illumination efficiency of incandescent lamps by reflecting infrared energy emitted by a filament back to the filament while transmitting the visible light portion of the electromagnetic spectrum emitted by the filament through the enclosure. The reflected infrared radiation heats the filament and reduces the amount of electrical energy required to maintain the filament operating temperature. Thus, the infrared reflective coating increases the illumination provided by a lamp for the same amount of energy input. The infrared reflective optical coatings can also improve the efficiency of an arc lamp in substantially the same manner.
One example of the use of an optical interference coating for reflecting infrared radiation in a halogen lamp is described in U.S. Pat. No. 5,138,219. The thin film infrared reflecting, optical interference filter is coated onto the outer surface of the lamp envelope to reflect infrared energy back to the filament. Although this glass halogen infrared reflecting lamp provides a benefit of improved lamp efficiency, it is relatively expensive to manufacture due to the large amount of coating material used to coat the enclosure and due to difficulties in mounting the lamp within the parabolic reflector.
It would therefore be desirable to provide an efficient lamp with an infrared coating which is less expensive to manufacture and easier to mount than the known lamps.
SUMMARY OF THE INVENTION
The present invention contemplates a new and improved single-ended glass halogen lamp which takes advantage of an infrared coating for maximum energy savings and also provides lower cost manufacturing than the known lamps.
In accordance with the present invention, a glass halogen lamp includes a lamp filament, a light transmissive lamp enclosure surrounding the lamp filament, and first and second electrical leads electrically connected to opposite ends of the lamp filament and both extending from a first side of the lamp enclosure. An ellipsoidal shroud is positioned about the lamp filament between the filament and the enclosure and a light-transmissive, infrared energy reflecting coating is formed on the ellipsoidal shroud to reflect infrared energy generated by the filament back to the filament to improve an efficiency of the lamp.
In accordance with a more limited aspect of the invention, at least one of the first and second electrical leads functions to support the ellipsoidal shroud within the enclosure.
In accordance with a further aspect of the present invention, an electrical lamp includes an electric light source, a shroud coated with an optical interference coating which reflects infrared radiation and transmits visible light, the shroud surrounding the light source and reflecting the infrared radiation emitted by the light source back to the light source, a hermetically sealed envelope surrounding the shroud, and an inert gas disposed within the envelope and surrounding the shroud and filament.
The principal advantages of the invention are energy savings provided by the infrared reflecting coating, low cost manufacturing due to the shroud and the single-ended lamp configuration, and ease of mounting.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.
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Day Michael H.
Fay Sharpe Fagan Minnich & McKee LLP
General Electric Company
Santiago Mariceli
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