Illumination – Light source and modifier – With ventilating – cooling or heat insulating means
Reexamination Certificate
1998-05-28
2001-02-06
Spyrou, Cassandra (Department: 2872)
Illumination
Light source and modifier
With ventilating, cooling or heat insulating means
C362S373000, C362S345000, C362S350000, C362S218000, C362S264000
Reexamination Certificate
active
06183114
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to light assemblies shielded to protect the surrounding material, in particular, to torchiere lights having a thermal shield to reduce the surface temperature accessible by surrounding materials.
BACKGROUND OF THE INVENTION
Within the last decade, open-top, upward facing “torchiere” style floor lights have become an increasingly popular source of lighting. However, the typical 300 watt torchiere light of this era incorporates a halogen lamp having a bulb external surface temperature of 794 K which presents heat energy sufficient to ignite many materials commonly found in the light operating environment. In fact, the lights are reported to be the source of many fires, leading institutions, e.g. colleges, to ban the lights outright.
Prior attempts to limit the problem have lead some manufacturers to install a wire mesh or glass covers in the region just above the bulb in models sometime advertised as “state of the art.” Such wire mesh or glass covers still provide an access to the hot bulb or themselves are above a temperature which can enflame some materials. In order to objectively evaluate the fire hazard problem, Underwriters Laboratory (UL) has proposed a “Cheesecloth” test, wherein an acceptable light must complete seven hours of continuous operation without burning or igniting a piece of cheesecloth placed on top (in the direction of the lights emission) of the light. The wire mesh or glass covers do not significantly reduce the fire hazard, and apparently offer protection to the bulb more than to the surrounding.
SUMMARY OF THE INVENTION
The present invention provides a light having a high temperature bulb in a shielded fixture housing which provides significantly reduced surface, radiation and convection temperatures to remove the fire hazard presented to the surrounding material which may be near or in contact with a surface of the light. The fixture housing includes the halogen bulb within a ventilated, tapered reflector. The bulb is placed at the narrowed end of the tapered reflector and a planar glass shield is placed at the wide end, covering substantially all of the opening thereof. The fixture housing typically includes an annular screen about the periphery of the glass shield and a vent below the bulb to provide an airflow through the fixture and reduced internal and surface temperatures.
Further improvements include electrical temperature sensors disposed at the glass shield to interrupt the power to the lamp if temperatures at the shield exceeded a safe temperature, thus offering added protection in the event of intentional or accidental misuse causing blockage of the flow of air through the vents and/or screen.
Thus, embodiments according to the present invention are expected to pass the “cheesecloth” test and to offer significantly reduced surface operating temperatures to provide a safe, reliable halogen light.
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Cook Kermit J.
Krakow Paul
Merrell Myles
Perry Darren
Boutsikaris Leo
Matzuk Stephen G.
Spyrou Cassandra
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