Electric lamp and discharge devices: systems – Time-controlled
Reexamination Certificate
2000-05-05
2001-03-27
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Time-controlled
C315S071000, C315S072000, C313S578000
Reexamination Certificate
active
06208090
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a lamp having compact filaments and, more particularly, to the hot shock failure mode known to occur in this type of lamp.
BACKGROUND OF THE INVENTION
With the introduction of high efficiency infrared reflective coated halogen lamps, the filament size has become more compact and, therefore, more susceptible to shock. Hot shock is a failure mode known to lamp makers where two or more primary or secondary turns of an incandescent filament touch, adhere to one another, and short out a portion of the active filament, resulting in an early burnout of the filament. Over the years, data has been collected from actual customer applications that indicate hot shock damage in this type of lamp occurs during the initial installation with the power on. As customers with hundreds of lamps complained of early hot shock failures, new lamps of the same design were installed with the power off, and the hot shock failures were greatly reduced. In a very few cases, the problem persisted due to vibration caused by construction in the area.
Presently, the primary solution to the hot shock problem requires that the filament be designed with increased spacing between turns of the filament and/or the addition of higher levels of nitrogen. In either case, the lamp efficacy is reduced, and in many cases, the only solution is to install the lamps with the power turned off.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an apparatus and a method to eliminate filament hot shock in lamp filaments, particularly in compact filament light sources such as high efficiency infrared reflective coated halogen lamps, during installation or during energization wherein the method comprises a voltage reduction circuit that reduces the voltage applied to the lamp filaments for a predetermined period of time and a timing circuit that is activated each time the lamp is energized and controls the predetermined period of time during which the voltage reduction circuit reduces voltage applied to the lamp filaments. As part of the apparatus, a one time latch circuit is optionally included to enable the timing circuit upon energization and disable it once the voltage reduction circuit has operated continuously for the predetermined period of time, and forever thereafter.
Use of the invention means that it is no longer necessary to increase is the spacing between turns of the filament or to add higher levels of nitrogen to the lamp tube to minimize hot shock. Both of the aforementioned remedies reduce the efficacy of the lamp, a drawback that is eliminated by the present invention.
REFERENCES:
patent: 4473776 (1984-09-01), Peters
patent: 4480212 (1984-10-01), Monahan et al.
patent: 4547704 (1985-10-01), Brinn et al.
patent: 4743803 (1988-05-01), Lanese et al.
Collins Edward J.
Hoegler Leonard E.
Lieszkovszky Laszlo V.
Skilskyj Ludwig
Fay Sharpe Fagan Minnich & McKee LLP
General Electric Company
Philogene Haissa
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