Electric lamp and discharge devices: systems – Plural load device systems – Electric switch in the supply circuit
Reexamination Certificate
1999-05-20
2001-06-12
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural load device systems
Electric switch in the supply circuit
C315S2090SC
Reexamination Certificate
active
06246187
ABSTRACT:
TECHNICAL FIELD
This invention relates to electrical assemblies for luminaires and, in particular, to an electrical assembly adapted to automatically turn off a light source so as to promote passive end of life light source failure in response to thermal cycling.
BACKGROUND ART
Indoor suspended lighting fixtures such as those used in warehouse and other commercial and retail settings typically utilize high intensity discharge (HID) lamps because of their superior efficiency and high light output. As those skilled in the art will recognize, however, these lamps and other high wattage light sources have been found to be susceptible to non-passive end of life failure particularly when operated continuously for all or a substantial part of their useful life.
Non-passive lamp failures generally occur in response to crack propagation of the associated arc tube. Specifically, when the internal arc tube ages and develops minute faults, the lamp may crack thus allowing the high pressure to force hot arc tube fragments through the outer glass jacket. If the associated luminaire is not suitably enclosed, falling arc tube fragments may, of course, pose a danger to personnel and property. Because many luminaires are not enclosed, non-passive end of life light source failure continues to be an issue of great concern to lamp manufacturers and lighting designers.
To prevent non-passive light source failures, high intensity discharge lamp manufacturers recommend periodic cycling of all lamps. Where lamps are used in applications that run continuously, lamp manufacturers require regular cycling typically once a week.
In operation, the high wattage light source such as, for example, an HID lamp, is periodically cycled off and then back on. An arc tube that has developed a weakness will fail during the cool down and subsequent warm up cycle because of the additional thermal contraction and expansion stresses experienced by the arc tube. To accomplish the required cycling of these lamps, the owner of the facility must de-energize then re-energize an entire electrical circuit. Because in many applications the lamps are running continuously, however, such cycling interrupts the facility's operation. Unless timers are attached to each circuit, there is also the possibility that an owner or her representative will not perform this cycling on a regular basis.
Consequently, a need exists for an improved electrical assembly for a luminaire which is adapted to automatically turn off a light source so as to promote passive end of life light source failure and substantially reduce or eliminate danger to personnel and property especially in open luminaire applications.
DISCLOSURE OF INVENTION
It is a principal object of the present invention to provide an improved luminaire and electrical assembly adapted to promote passive end of life light source failure.
It is a further object of the present invention to provide such an electrical assembly which is adapted to turn off the associated lamp.
It is a further object of the present invention to provide such an electrical assembly which is adapted to interrupt power to the associated lamp for predetermined periods of time.
It is yet a further object of the present invention to provide such an electrical assembly which is adapted to interrupt power to the associated lamp at predetermined or random times thereby reducing or eliminating the associated design and labor costs of installing special wiring for an array of luminaires.
It is still a further object of the present invention to provide such an electrical assembly which is adapted to interrupt power to the associated lamp for predetermined or random durations.
Still further, it is an object of the present invention to provide an electrical assembly which is adapted to turn off the lamp at predetermined or random periods of time for predetermined or random durations by shorting it out.
In carrying out the above objects and other objects, features, and advantages of the present invention, there is provided an improved electrical assembly for a luminaire. The assembly includes a ballast adapted to power a light source and an automatic relay device. The automatic relay device is provided in electrical communication with the ballast and is adapted to receive power from a power source such as a utility feed. In operation, the relay device interrupts power to the ballast and thus the light source for predetermined periods of time so as to promote passive end of life light source failure in response to thermal cycling of the light source.
In an alternative embodiment, the light source itself is shorted out. This is typically, but not necessarily, accomplished by placing the relay device in parallel with the secondary circuit of the ballast.
The cycling provided by the invention is typically, but not necessarily, random. Such cycling allows individual lamps or groups thereof to be temporarily de-energized without disrupting the application such as would occur if entire lighting circuits were powered off.
REFERENCES:
patent: 3914690 (1975-10-01), Shelnutt
patent: 4488092 (1984-12-01), Chikuma
patent: 4547705 (1985-10-01), Hirayama et al.
patent: 4847536 (1989-07-01), Lowe et al.
patent: 4853599 (1989-08-01), Singarayer
patent: 4912375 (1990-03-01), Déglon et al.
patent: 4996463 (1991-02-01), Horowitz
patent: 5103193 (1992-04-01), Von Bokern
Dinh Trinh Do
NSI Enterprises Inc.
Wong Don
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