Illumination – Light source and modifier – Ionized gas or vapor light source
Reexamination Certificate
1999-06-25
2001-06-19
Tso, Laura K. (Department: 2875)
Illumination
Light source and modifier
Ionized gas or vapor light source
C313S011000, C313S013000, C362S294000
Reexamination Certificate
active
06247830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a heat shield for agricultural light bulbs and more particularly, to an air-cooled light fixture having a transparent cylinder that surrounds a high intensity discharge lamp for providing a continuous air path for removal of heat from the fixture.
2. Description of Related Art
High intensity light sources, such as agricultural bulbs, sealed beam lamps and the like, include optical devices which direct the light therefrom along a narrow beam path. These lamps get exceptionally hot when confined to a small area. It is important to operate these lamps at or as near as possible to their recommended operating temperatures. Higher than optimum temperature operation reduces their life span and lower temperatures prevent inert gas contained in many such lamps from returning tungsten from the bulb wall to the filament coils which blackens the lamp walls causing a reduced intensity output.
Several air-cooled light fixture designs in common use have sheet metal enclosures used in combination with borosilicate glass for providing a heat shield to insulate outside surroundings from heat generated by these light fixtures. However, the sheet metal enclosures typically get very hot during operation and radiate substantial heat to the surroundings. Additionally, several of these light fixture designs have channels formed inside the light fixtures that have nonlinear contours, thereby producing increased mechanical losses from airflow through the light fixtures and thereby reducing air-flow capacity associated with the channels. For example, U.S. Pat. No. 4,546,420, issued Oct. 8, 1985 to Wheeler et al. discloses an air-cooled light fixture having an air channel defined by several structural members projecting inwardly to form a jagged-shaped air-path. Such jagged air-paths impair the capacity of an air channel to cool the light fixture by restricting an air flow path. Similarly, German patent number S 41624 discloses an air-cooled light fixture having an enclosure surrounding a lamp with a channel formed in the enclosure for passing air through the light fixture. However, German patent number S 41624 does not disclose the light fixture having a straight and continuous channel for air flow. Consequently, heat removal by an air-cooling means cannot occur at a maximum flow rate. Great Britain patent number 721,585 discloses an air-cooled light fixture having a glass enclosure surrounding a fluorescent tube, wherein connected to a side wall of the enclosure are two conduits serving as an inlet and a outlet for passing air flow inside the light fixture. However, Great Britain patent number 721,585 does not disclose a light fixture having a straight and continuous air-channel configuration permitting maximum flow of air through the light fixture.
Several patents disclose a light fixture having a glass cylinder surrounding a light. For example, U.S. Pat. No. 5,489,813, issued Feb. 6, 1996 to Jung discloses a neon lamp including a transparent outer tube for preventing water from entering the lamp. However, U.S. Pat. No. 5,489,813 does not disclose a means for air cooling the lamp. U.S. Pat. No. 5,612,585 discloses a high-pressure discharge lamp including an outer envelope surrounding a discharge tube and a heat shield. However, U.S. Pat. No. 5,612,585 does not disclose the outer envelop as a heat shield.
A shortcoming of some common air-cooled light fixtures is their inability to sense the temperature of a light fixture and terminate electrical power to that light fixture when its temperature exceeds a predetermined maximum safe operating temperature. Another shortcoming of some air-cooled light fixtures is their lack of adaptability for being connectable to exhaust systems having varying air-flow capacities. Still another shortcoming of some common air-cooled light fixtures is an absence of waterproofing for protecting the light fixture from water damage. Yet still another shortcoming of some air-cooled light fixtures is an inability to be connected to outside sources of ventilation air.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed, nor fulfill the needs or problems as set forth above. Thus an improved air-cooled light fixture is desired.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the invention to provide an air-cooled light fixture having a straight and continuous air channel passing therethrough for allowing outside air to be easily passed through the light fixture for maximum heat removal.
It is another object of the invention to provide an air-cooled light fixture that is adapted to being connected to exhaust systems having varying air-flow capacities.
It is a further object of the invention to provide an air-cooled light fixture that is water-proof for providing water protection for internal electrical components against water damage.
Still another object of the invention is to provide an air-cooled light fixture having a thermal protector for disconnecting electrical power to the light fixture when temperature inside the light fixture exceeds a predetermined maximum safe operating temperature.
It is yet another object of the invention to provide an air-cooled light fixture capable of being attached to an outside source of ventilation air.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
In accordance with these and other objectives, the present invention is an air-cooled light fixture having a transparent cylinder that surrounds a high intensity discharge lamp for insulating heat generated by the high intensity discharge lamp from outside surroundings. In a preferred embodiment, the transparent cylinder is made of a borosilicate glass, for example, PYREX or KIMAX. Sealingly attached to opposing ends of the transparent cylinder are two end plates for supporting the light fixture from a ceiling structure. The high intensity discharge lamp is supported inside the transparent cylinder by fixedly attaching one end of the high intensity discharge lamp to one of the two end plates. Attached to one end of each of the two end plates is a hose flange for providing a means for connecting a hose to each end plate. Mounted to an inside wall of the transparent cylinder is a thermal protector device for disconnecting electrical power to the high intensity discharge lamp when a temperature inside the transparent cylinder reaches a predetermined temperature limit.
A circular curtain of air is pushed or pulled through the cylindrical transparent sleeve by blowers or fans. The rapidly moving flow of air continuously removes the heat generated by the high intensity discharge lamp. The ends of the transparent cylinder are connected to an exhaust hose and the exhaust hose is connected to fans or an exhaust vent that removes heat from the lamp fixture. The transparent cylinder not only functions as a heat shield but also serves as a safety barrier between the lamp and the outside environment should the lamp explode, whereby the glass from the lamp is retained within the fixture by the cylindrical transparent sleeve of the present invention. A reflective hood is used to reflect light emanating from the top surface of the lamp downwards towards the ground.
Although, in the preferred embodiment of the present invention the transparent cylindrical sleeve is made of a borosilicate glass, the transparent cylindrical sleeve could be made from any suitable transparent material, for example, a plastic. Therefore, any material that is transparent and capable of withstanding high temperatures could be used. Additionally, although the preferred embodiment of the present invention is directed towards a transparent sleeve having a cylindrical shape, the transparent sleeve could have various other shapes such as square, rectangular, hexagonal, octagonal,
Fanelli Michael
Winnett Russell
Litman Richard C.
Tso Laura K.
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