Illumination – Light source and modifier – Including reflector
Reexamination Certificate
1999-09-15
2001-07-03
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S342000, C362S297000, C362S346000, C362S223000
Reexamination Certificate
active
06254255
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a luminaire having a housing with a concave reflector with a plane of symmetry and a light emission window, and a holder for positioning an electric lamp in the plane of symmetry. The reflector has first opposing walls having flat strips extending along the plane of symmetry, second opposing walls transverse to the plane of symmetry, and a top wall opposite the light emission window.
Such a luminaire is disclosed in U.S. Pat. No. 5,564,820.
The known luminaire may be mounted in a ceiling. The flat strips of the first walls serve to spread the light generated by an accommodated lamp in directions transverse to the plane of symmetry. However, the strips do give rise to second reflections at the second walls. The second walls are flat, between straight bending lines along the light-emission window, so as to widen the light beam in the longitudinal direction of the lamp to be accommodated.
The known luminaire has the drawback that the reflector is voluminous, thus requiring the housing to be relatively large, particularly if the housing must accommodate means for feeding and starting the mounted lamp.
DE-A-1 904 982 discloses a luminaire in which reflectors are present in a housing situated at the side of a high-pressure discharge lamp arranged in a plane of symmetry. The reflectors are composed of flat strips extending along the light-emission window, and having a bending line in surfaces extending transversely to the light-emission window, the strips being bent towards each other along the bending line. The flat strips may flare out from the bending lines of the light-emission window. Opposite the light-emission window, the reflectors are covered with a flat reflector.
This luminaire too is very voluminous, while, in addition, the housing is closed with a dish-shaped transparent shield, parts of which extending perpendicularly to the light-emission window being used as an optical screen.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a luminaire of the type described in the opening paragraph, which is of a compact construction.
In accordance with the invention, this object is achieved in that the top wall has an aperture in the plane of symmetry S, which is covered with a reflective shade,
said shade including first opposing surfaces extending along the plane of symmetry, second opposing surfaces extending transversely to the plane of symmetry S, and a top surface opposite the light-emission window,
the means being positioned so as to keep the electric lamp e.
1
. to be accommodated in place in the aperture.
The shade narrows the reflector at some distance from the light-emission window, thus enabling the lamp to be accommodated to be substantially half surrounded, in the plane of symmetry and in a plane transverse thereto, with much smaller reflecting surfaces. As a result, also the dimension of the reflector transverse to the light-emission window is smaller and the luminaire is compact. Besides, relatively expensive reflector material is saved.
It is favorable if the first surfaces of the shade comprise flat strips extending along the light-emission window. As a result, the spread of the light generated by an accommodated lamp in directions transverse to the plane of symmetry is better than it would be if the first surfaces were bent.
In a favorable embodiment, the second surfaces of the shade are flat and, towards the top surface, the distance between them decreases. In a variant of this embodiment, also the second walls are flat and the distance between them decreases in the direction of the top wall.This embodiment, and the variant thereof, have the advantage that light incident on these reflector parts is spread strongly in the direction of the plane of symmetry and in the surrounding directions.
In an advantageous embodiment, the first walls are provided with a bend in surfaces extending transversely to the light-emission window, so as to form a center panel and side panels connected thereto. In this manner, it is counteracted that light is reflected by a first wall onto a second wall. Reflection at a second wall would cause a loss of light, since each reflection is accompanied by absorption.
In a particular embodiment, the first walls are bent so strongly that light incident on the side panels diagonally traverses the reflector upon reflection, so as to form a wide beam transverse to the plane of symmetry. This additionally results in second reflections at the second walls being precluded even more. For this purpose, the side panels generally include an angle ranging from 130 to 135° with each other in the light-emission window. The reflectors of the above-mentioned DE 1 904 982 are bent much more faintly.
Contrary to what is stated in the document mentioned in the previous paragraph, in a favorable variant of the two embodiments just mentioned, the flat strips in the side panels extend from the center panel towards the light-emission window. As a result, the incident light is sent out by the side panels at a larger angle with respect to the light-emission window. Consequently, the light in question forms a better supplement to the light reflected by the center panel, as will be apparent from FIG.
5
.
It is advantageous if the top surface has a bent, convex fold which extends in the plane of symmetry. In this case, the light reflected by the relevant reflector part is not cast back to the lamp, but is spread in directions transverse to the plane of symmetry.
Preferably, a flat transparent shield is used to close the light-emission window. The transparent shield precludes soiling of the reflector and can be readily cleaned. In addition, a flat transparent shield, for example of glass or a synthetic resin, is easy to manufacture.
It is also preferred that the reflector has a first and a second lamella in the light-emission window at and along each one of the second walls. The lamellae limit, in the direction of the plane of symmetry and in directions surrounding the plane of symmetry, the angle with the light-emission window at which light is emittted. The reflector gives such a limitation in directions transverse to the plane of symmetry. When the transparent shield is removed, the lamellae nevertheless do not hamper the exchange of the lamp in the luminaire, since the lamp can be passed between the lamellae.
The luminaire can very suitably be used to accommodate a lamp with a light source whose length in the plane of symmetry is greater than its width in directions transverse thereto, for example a halogen incandescent lamp or a high-pressure discharge lamp, such as a high-pressure sodium lamp or a high-pressure mercury lamp, for example containing metal-halide additions, and having, for example, a quartz-glass or ceramic envelope, such as an envelope of aluminium oxide.
The luminaire can particularly suitably be used to illuminate traffic areas provided with a roof, such as petrol stations.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.
REFERENCES:
patent: 5564820 (1996-10-01), Entrop et al.
patent: 5806972 (1998-09-01), Kaiser et al.
patent: 1904982 (1970-08-01), None
Entrop Jean P.
Wijbenga Hendrik
DelGizzi Ronald E.
Halajian Dicran
O'Shea Sandra
U.S. Philips Corporation
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