Illumination – Light source and modifier – Including reflector
Reexamination Certificate
1999-05-20
2002-03-19
Cariaso, Alan (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S260000
Reexamination Certificate
active
06357894
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel lighting fixture which is particularly useful for employing compact fluorescent lamps.
Downlights are widely used to uniformly distribute light on a surface. In the past, incandescent “A-lamp” downlights were employed as the preferred system for downlighting applications, because such fixtures exhibited excellent brightness control and uniform distribution. The basic construction and “A-lamp” downlight includes a round incandescent lamp enclosed by a symmetrical circular appearing reflector.
Recent concerns with the cost of operating incandescent lamps has motivated the substitution of fluorescent lamps for incandescent lamps in downlight applications. Such fluorescent lamps are referred to as “PL” or “CFL” types. Compact fluorescent lamps are found in various configurations and wattages. For example, twin, quad, triple, and the like configurations are used in these lamps. Unlike round incandescent lamps, compact fluorescent lamps are, by nature, asymmetrical, especially when compact fluorescent lamps are positioned horizontally within the lighting fixture. Lighting fixtures utilizing compact fluorescent lamps, in the past, have encountered many problems. For example, “visual noise”, such as striations, hot spots, distorted images, and the like, have been generated by horizontally positioned compact fluorescent lamps in downlights. In addition, the actual viewing of the horizontally positioned compact fluorescent lamp by an observer below the fixture creates a unfavorable aesthetic image. Moreover, glare from the reflector systems used with such fluorescent lamps is also pervasive in fluorescent downlight fixtures presently available. Although such problems have existed, there has been no alternative solution but to use fluorescent lamps in place of incandescent lamps in downlights, and to tolerate the many problems which have been delineated above.
Reference is made to U.S. Pat. Nos. 4,519,019, 5,045,982, and 5,515,255 which show reflector systems for ceiling lights which are generally of the incandescent type. Reflectors described in these patents are generally curved and lie above the lamp.
U.S. Pat. No. 5,582,479 shows a dual reflector system in which an incandescent lamp is used. One reflector is formed within the other reflector in this construction.
A lighting fixture utilizing a fluorescent light source that possesses many of the characteristics of an incandescent downlight would be a notable advance in the lighting field.
SUMMARY OF THE INVENTION
In accordance with the present invention a novel and useful downlight fixture utilizing a fluorescent light source is herein provided.
The lighting fixture of the present invention includes a housing which surrounds the fluorescent light source. The housing possesses an aperture that is defined by an edge portion. The aperture permits light to flow from the light source, while the edge portion of the aperture determines the cutoff angle of the light emanating from the fluorescent light source. The housing may be recessed in a ceiling or wall or be surface mounted as desired by the user.
The light source is generally in the form of a fluorescent lamp. Such fluorescent lamps are constructed in compact form, having one, two, three, or other number of tubes for the generation of light. The fluorescent light source may be mounted horizontally relative to the plane of the aperture of the housing.
A first reflector is formed on the inner surface of the housing to direct light from the fluorescent light source at certain angles. From the optical axis, which is generally coincident with the axis of the fixture, light is directed at angles ranging between the cutoff angle, determined by the housing edge portion, and at angles less than the cutoff angle. The first reflector, when the lighting fixture of the present invention is used in a ceiling, generally surrounds the top portion of the fluorescent lamps serving as the source of light. Of course, the first reflector may be specular surface, in this regard.
A second reflector is also formed on the inner surface of the housing. The second reflector is located adjacent the first reflector and may be, essentially, contiguous with the first reflector. The second reflector lies between the housing aperture and the first reflector, in any case. Light from the fluorescent source is directed by the second reflector outwardly through the aperture of the housing at a selected angle, which is less than the cutoff angle, and at other angles which are less than such selected angle. Thus, there is a gap between the highest angles of reflection of the first and second reflectors which creates a desirous “optical delay” from the perspective of an observer on the surface below the lighting fixture of the present invention, which will be detailed hereinafter. In addition, the second reflector is so formed that, as an observer approaches the optical axis of the fixture, becomes active beginning at the portion of the second reflector immediately adjacent the first reflector and continuing outwardly therefrom, as the observer moves closer to the optical axis. The result is that the present invention creates a reflector system that very closely mimics the effects of an incandescent lamp downlight and eliminates “visual noise” inherent in the prior art fluorescent downlights.
It may be apparent that a novel and useful lighting fixture has been described.
It is therefore an object of the present invention to provide a lighting fixture utilizing a fluorescent light source in the form of a highly asymmetrical horizontal compact fluorescent lamp, which produces a light distribution which is essentially symmetrical.
Another object of the present invention is to provide a lighting fixture utilizing a fluorescent light source which is suitable for a recessed lighting fixture and possesses minimum “visual noise” of the kind found in prior art fluorescent downlights.
A further object of the present invention is to produce a lighting fixture utilizing a fluorescent light source which includes a reflector system that results in projected light having an aesthetic quality similar to light emanating from an incandescent lamp.
Yet another object of the present invention is to provide a lighting fixture utilizing a fluorescent light source which is capable of operating with fluorescent lamps of various configurations.
Another object of the present invention is to provide a lighting fixture utilizing a fluorescent light source which is visually pleasing to an observer on the surface below the lighting fixture through the use of one of the reflectors of the reflector system of the lighting fixture of the present invention, which possesses an “optical delay” as the observer approaches the fixture.
Yet another object of the present invention is to provide a lighting fixture utilizing a fluorescent light source which possesses the qualities of sharp cutoff, low luminance, and high visual comfort probability, under accepted industry standards.
Another object of the present invention is to provide a lighting fixture utilizing a fluorescent light source which exhibits low glare.
The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues.
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Chu Wai-Lam
Latsis Chris
Bielen, Jr. Theodore J.
Cariaso Alan
Prescolite Inc.
Sawhney Hargobind S.
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