Illumination – Light source and modifier – Fluorescent type
Reexamination Certificate
1996-06-12
2001-02-27
Quach, Y. (Department: 2875)
Illumination
Light source and modifier
Fluorescent type
C362S225000, C362S298000, C362S346000
Reexamination Certificate
active
06193394
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to architectural lighting, and more particularly relates to luminaires that provide both direct and indirect lighting, so-called “direct-indirect” luminaires. The invention finds particular application in the field of linear fluorescent lighting where ambient light is produced from fluorescent lamps mounted in an elongated housing having a predetermined length and characteristic cross-sectional shape.
Linear direct-indirect lighting has been known for many years. Such fixtures normally provide indirect or “up” lighting through the top of the luminaire housing which is open (or is covered by a light transmitting element such as a lens cover), and a direct or “down” lighting component through one or more openings in the bottom of the housing, openings which are typically covered by lenses, baffles, or louvers to shield the luminaire's fluorescent lamps from direct view. Such shielding is desirable since exposure of the lighting emitting surfaces of the lamps within the luminaire through the direct light openings can produce uncomfortable visible brightness and distracting glare on work surfaces.
The disadvantage with existing direct-indirect lighting luminaires is that in many designs, the lamps are not adequately shielded from all viewing angles from below the luminaire leading to a condition where, at certain angles, the bright surfaces of the lamps project through the luminaire's down light openings with detrimental consequences to the lighting environment. In the present invention, the lamps of a direct-indirect luminaire are totally shielded from view through the fixture's down light openings regardless of the viewing angle. At the same time the amount of light available to the down light openings can be maximized.
SUMMARY OF THE INVENTION
Briefly, the invention involves a direct-indirect luminaire comprised of a housing having an up light opening and at least one down light passage area. A light source is mounted in the housing for producing indirect light through the housing's up light opening and a direct lighting component through its down light passage area. The down light passage area can be any opening or combination of openings through which light can pass through the bottom of the housing, for example, the passage area can be an elongated completely open slot or a baffle plates having a series of punched openings along its length. To shield the light source from direct view at any viewing angle from below the luminaire, a shielding element is mounted internally of the housing to laterally extend between the light source and the down light passage area so as to prevent any line of sight exposure of the light source through the light passage area. Preferably, the shielding element will extend laterally in the direction of the light passage area a distance that is only sufficient to prevent line of sight exposure of the light source surfaces. Further extension of the shielding element would reduce the amount of source light available to the light passage area thereby reducing the down light component of the luminaire.
In the illustrated embodiment the direct-indirect luminaire of the invention has an elongated housing with at least one elongated light passage area having an interior edge and an anterior edge extending longitudinally of the housing. A light source, suitably a linear fluorescent lamp, is mounted to extend generally above and in line with the interior edge of the down light passage area while the shielding element extends both longitudinally of the housing generally over the interior edge of the light passage area and laterally toward the anterior edge of the light passage area a sufficient distance to prevent line of sight exposure of the light source. Preferably, a primary reflector surface extends internally of the housing from the anterior edge of the light passage area for reflecting source light onto the light passage area and a secondary reflector surface extends internally of the housing from the interior edge of the down light passage area for redirecting source light onto the down light passage area received from the primary reflector surface. Suitably, the secondary reflector surface and shielding element can be fabricated of a single bent metal reflector element. It is contemplated that the primary reflector will be a substantially diffuse reflector, while the secondary reflector range from diffuse to specular.
Therefore, it is a primary object of the present invention to provide a direct-indirect luminaire which reduces the potential for uncomfortable source brightness or distracting glare. It is a further object of the invention to achieve the foregoing objective while having the ability to maximize the amount of source light available through the down light passage area of the luminaire. It is a further object of the invention to provide a direct-indirect luminaire which is relatively simple in construction. Other objects of the invention will be apparent from the following specification and claims.
REFERENCES:
patent: 2874271 (1959-02-01), Lipscomb
patent: 3389246 (1968-06-01), Shemitz
patent: 4768140 (1988-08-01), Szpur
patent: 4939627 (1990-07-01), Herst et al.
patent: 5192128 (1993-03-01), Ngai
patent: 0064805 (1991-03-01), None
Herst Douglas J.
Ngai Peter Y. Y.
Beeson Donald L.
NSI Enterprises Inc.
Quach Y.
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