Illumination – Elongated source light unit or support – Plural sources or supports therefor
Reexamination Certificate
1999-07-21
2001-06-26
Cariaso, Alan (Department: 2875)
Illumination
Elongated source light unit or support
Plural sources or supports therefor
C362S223000, C362S291000, C362S342000, C362S220000, C362S372000
Reexamination Certificate
active
06250772
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a luminaire comprising:
a concave reflector with a longitudinal direction, a light-emission window and a plane of symmetry S extending in the longitudinal direction and transversely to the light-emission window;
means for incorporating in the reflector, along the light-emission window, a first electrical fluorescent tube and a second electrical fluorescent tube;
lamellae in the light-emission window, which extend transversely thereto and transversely to the longitudinal direction of the reflector.
Such a luminaire is disclosed in EP-B-0 638 764.
The known luminaire is a twin luminaire, in which both reflectors accommodate a compact fluorescent lamp having two parallel fluorescent tubes. The lamps are each arranged such that both tubes extend in the relevant plane of symmetry. Both parts of the luminaire illuminate a surface right below the luminaire, which is mounted in or to a ceiling. Each one of the two reflectors is provided with a slit at the side of the relevant lamp, allowing a part of the light generated to be guided from the luminaire to the exterior via auxiliary reflectors situated at the side of the (main) reflector. A transparent prism may be arranged in the path of the light so as to laterally deflect the light.
The known luminaire has the drawback that it has a relatively large width dimension and that its construction is relatively complicated. The luminaire is provided with transparent prisms, causing the luminaire to cast a part of the light in the direction of the ceiling. Without prisms, the auxiliary reflectors increase the light-emission window, however, in that case the light beam is used entirely to illuminate a horizontal surface, such as the floor or a worktop. Vertical surfaces are poorly lit and, in addition, at places relatively close to the ground.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a luminaire which is of a simple construction and can suitably be used to illuminate surfaces extending transversely to the light-emission window.
In accordance with the invention, this object is achieved by positioning the first electrical fluorescent tube and the second electrical fluorescent tube on either side of the plane of symmetry;
a predominantly prismatic reflector element having a top, a base and sides facing the reflector is present, which reflector element extends in the plane of symmetry S, the base being situated close to the light-emission window, and the top being situated close to the fluorescent tubes.
If the luminaire is mounted in or to a ceiling, then the luminaire illuminates, through reflections at a side face of the prismatic element, relatively high parts of a nearby, first vertical surface, while the part of the reflector situated opposite said side face illuminates relatively low parts of said surface. The other side face of the prismatic element, and the part of the reflector opposite said side face, illuminate a second vertical surface situated opposite the first surface. The floor area below the luminaire is in fact only lit to a small degree, predominantly by rays leaving the luminaire without previous reflection at the reflector and the prismatic element.
The reflector also screens the fluorescent tubes in directions transverse to the tubes, so that the tubes are invisible from a chosen angle with the ceiling. The lamellae have a similar function in the longitudinal direction of the reflector and in directions around the longitudinal direction.
The luminaire in accordance with the invention can very suitably be used to illuminate articles in, for example, racks, cupboards, shelves, etc., in, for example, storehouses, shops and libraries.
In a favorable embodiment, the side faces of the prismatic reflector element are concave in the direction from the base to the top. In particular, the side faces have flat strips which are situated between bending lines extending along the light-emission window. By virtue thereof, the prismatic element provides for an improved light distribution and for illumination at higher places.
Favorably, the side faces near the top are substantially parallel, and the means for accommodating the fluorescent tubes can be moved in a direction transverse to the light-emission window. This embodiment has the advantage that the prismatic element can readily extend between the tubes. By virtue of the movability of the means, the luminaire can be adapted to local conditions. If the means are moved towards the light-emission window, then the light flux towards relatively high places is increased. In this case, the prismatic element between the tubes counteracts a reduction of the angle with the ceiling at which the tubes are invisible. Said shape of the prismatic reflector element is also favorable, however, if the means cannot be moved.
In a favorable embodiment, the reflector has flat strips which are interconnected along bending lines extending parallel to the light-emission window. This embodiment has the advantage that the light reflected by the reflector is spread more over the relatively low parts of a vertical surface.
In a variant, the reflector has a convex bending line in the plane of symmetry. This has the advantage that also the top-of the reflector contributes to the illumination of a vertical surface.
It is favorable if cylindrical end reflectors end the row of lamellae, said reflectors having an axis which extends along the light-emission window. By virtue thereof, the light emitted by the tubes in their longitudinal direction is effectively used.
In an advantageous embodiment, the reflector is divided into a plane P along the light-emission window, at some distance from the lamellae. This embodiment enables the lamellae and the prismatic element to be interconnected so as to form an inextricable unit, while the fluorescent tubes can still be readily exchanged by removing said unit.
The reflector, the lamellae and the prismatic element may be manufactured from a lacquered material, for example a plate material. Alternatively, they are made of a reflective metal, such as aluminium or an alloy thereof. They may be mat, mirror-bright or semi-bright. If the lamellae are bright, they are preferably prismatic with their top in the light-emission window. The lamellae then preferably have concave, for example parabolic side faces, in order to deflect incident light downward.
The fluorescent tubes may each be a fluorescent lamp or jointly constitute the limbs of one compact fluorescent lamp.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 3909100 (1975-09-01), Hodge, Jr.
patent: 4420798 (1983-12-01), Herst et al.
patent: 4866584 (1989-09-01), Plewman
patent: 5806972 (1998-09-01), Kaiser et al.
patent: 5855427 (1999-01-01), Lassovsky
patent: 6109766 (2000-08-01), Baliozian
patent: 3129689 (1983-02-01), None
patent: 0638764 (1996-06-01), None
patent: 2301176 (1996-11-01), None
Entrop Jean P.
Wijbenga Hendrik
Cariaso Alan
DelGizzi Ronald E.
Halajian Dicran
U.S. Philips Corporation
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