EP0564022A1

EP0564022A1 - A lighting fixture

Info

Publication number: EP0564022A1
Application number: EP93200727A
Authority: EP
Inventors: Simon Cornelis Van Putten
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-03-30
Filing date: 1993-03-12
Publication date: 1993-10-06
Anticipated expiration: 2013-03-12
Also published as: NL9200579A; EP0564022B1; DE69306632D1; DE69306632T2; ATE146582T1

Abstract

A lighting fixture comprising a box-shaped housing (1). The housing (1) has a rectangular bottom plate (2) and four side plates defining a rectangular lighting aperture (6). An elongated light source (7) is provided parallel to and between the bottom plate (2) and the lighting aperture (6). A means (20) hiding the light source from view is provided parallel to and beween the elongated light source (7) and the lighting aperture (6). This means (20) may be supported on two longitudinal lamellae (18,19) placed above the lighting aperture (6) and may be an opal plate or a lens having a hexagonal series of semi-spherical refractory elements. An auxiliary means, such as a flush-mounted halogen lamp or a loudspeaker may be provided in the means (20) hiding the light source from view or in a similar additional auxiliary plate. The means (20) hiding the light source from view may furthermore be partially diffused or be reflecting at its bottom side.

Description

The invention relates to a lighting fixture comprising a box-shaped housing having a rectangular bottom plate and a first and a second pair of parallel side plates, said side plates being connected to the bottom plate and defining a rectangular lighting aperture, a lamp holder for an elongated light source secured to the inner side of a respective side plate of said first pair of side plates, and a pair of longitudinal lamellae provided parallel to said second pair of side plates, being spaced from said second pair of side plates, from each other and from the lighting aperture.
Such a lighting fixture is known from Dutch Patent Application 89 00 477.
The known lighting fixture includes transverse lamellae, which are provided between said pair of longitudinal lamellae, parallel to said first pair of side plates.
The advantages of the known lighting fixture are the high lighting efficiency, the absence of point luminance and a low brightness value.
A defect of the known lighting fixture is, however, that the light source remains visible.
The object of this invention is to overcome this defect, while retaining the advantages already attained or even achieving an improvement with respect thereto.
In order to accomplish this objective the invention provides a lighting fixture of the kind mentioned in the preamble, which is characterized in that at the upper side of said pair of longitudinal lamellae means are provided which bridge the distance between said second pair of longitudinal lamellae and which hide said light source from view.
Because of this feature the light source is completely hidden from view, both in transverse direction and in longitudinal direction, and that without interfering with the ventilation inside the lighting fixture.
The design parameters or adjusting possibilities include the mutual distance of the longitudinal lamellae and the distance from the bottom side of the longitudinal lamellae to the lighting aperture.
Grids of metal or plastic material, prismatic and opal plates, partially diffused acrylate plates and partially diffused plates, mirroring on one side, of glass or plastic material are used as the means hiding the light source from view.
An auxiliary means, such as a flush-mounted halogen lamp, a loudspeaker, a fire or smoke detector, an infrared detector or a wall socket may be provided in the means hiding the light source from view itself or in an additional, similarly provided auxiliary plate of metal or plastic material.
The lighting fixture according to the invention is adapted for the use of electromagnetic as well as high frequency ballasts.
The invention will be further explained hereafter with reference to the drawing, which consists of a single Figure, which diagrammatically shows a possible embodiment of a lighting fixture incorporating the present invention.
In the Figure reference numeral 1 indicates a box-shaped housing of a lighting fixture according to the invention, which is diagrammatically illustrated in cross-section. The box-shaped housing 1 has a rectangular bottom plate 2, a first pair of side plates extending parallel to each other and to the plane of the drawing, one of said side plates being indicated at 3, and a second pair of parallel side plates 4, 5, said four side plates being connected to the bottom plate 2 and defining a rectangular lighting aperture 6. Reference numeral 7 indicates an elongated light source 7, which is provided in the lighting fixture at a possible location, which is shown by way of example. Said light source 7 may be a fluorescent lamp, a conventional lamp or a more modern, compact one, in which case one or more lamp holders (not shown) will be secured to both side plates of the first pair, of which only side plate 3 is shown, for receiving one or more light sources 7 in one or more positions. Of course only one lamp holder needs to be provided on one of the side plates of the first pair of side plates, for example side plate 3, when light sources 7 adapted for connection at one of their ends are used. Reference numerals 8 and 9 indicate side reflectors, which are secured to the housing 1 with one of their ends, the bottom ends in this case. The opposite ends, the upper ends in this case, may be fixed to the housing 1, or be secured to said housing by means of an adjusting means (not shown), which makes it possible to give various curvatures to the side reflectors 8, 9, also with respect to each other. Reference numeral 10 indicates a head mirror which, as shown, may be formed in such a manner that it is profiled in the centre, i.e. curved towards the light source(s) on both sides of the axial line, contiguous thereto. The fixture bottom may also be depressed to form a head reflector. Reference numerals 11 and 12 indicate two longitudinal lamellae, which are a continuation of the side reflectors 9 and 8 respectively. This makes it possible to select different reflecting characteristics for the side reflectors 8 and 9 on the one hand and the longitudinal lamellae on the other hand. The side reflectors may extend as far as the lighting aperture 6, leaving out the longitudinal lamellae 11 and 12. If the longitudinal lamellae 11 and 12 are provided, then their configuration is in principle determined by that of the side reflectors 8 and 9, of which they are a continuation. Numerals 18 and 19 indicate two supplementary longitudinal lamellae, whose configurations may differ from the side reflectors 9 and 8 as well as from each other, their curvatures for example being different. In the embodiment shown in the Figure the lamellae 18 and 19 have a wedge-shaped section, however, whereby the sides facing away from each other extend vertically and whereby the sides facing each other lie at an angle to the vertical, said angle being smaller than 25^o in one embodiment. The reason for this is the following: If said angle is larger than 25^o, double reflections will occur, thus reducing the efficiency of the fixture. If said angle is smaller than 25^o, the luminous flux will flow along the supplementary longitudinal lamella, so that double reflections do not occur. The supplementary longitudinal lamellae 18, 19 are thus provided parallel to the second pair of side plates 4, 5, being spaced from said second pair of side plates, from each other and from the lighting aperture 6. Setting aside the specific configuration of the supplementary longitudinal lamellae 18, 19, thus far the lighting fixture shown in the Figure is in principle of conventional design and for example corresponds with the fixture described and shown in the Dutch Patent Application referred to in the preamble.
It is noted in passing that although the Figure shows an flush-mounted fixture, the invention may also be used in other lighting fixtures, such as surface mounted lighting fixtures, while retaining the same advantages.
In accordance with the invention the lighting fixture shown in the Figure is provided, at the upper side of the pair of supplementary longitudinal lamellae 18, 19, with means 20 bridging the distance between the pair of supplementary longitudinal lamellae 18, 19 and hiding the light source 7 from view, said means being an opal plate 20 in the illustrated embodiment, i.e. a plate which is non-translucent on one side and translucent on the other side. The effect of the opal plate 20 is that the light source 7 is hidden from view and thus cannot be reflected, or at least less, in a display screen positioned under the lighting fixture. In other words, undesirably high luminance in display screen equipment is shielded. This is particularly advantageous with bright fluorescent lamps having a diameter of 21 or 26 mm, for example compact lamps of 40 - 55 watt. As an alternative for the supplementary longitudinal lamellae 18, 19 means may be provided, for example guide channels, for carrying the means 20 shielding the light source. Instead of an opal plate it is also possible to use a quadratic grid as the means 20 hiding the light source from view. Generally, and not exhaustively so, grids of metal or plastic material, prismatic and opal plates, partially diffused acrylate plates and partially diffused plates, mirroring on one side, of glass or plastic material may be used. The term partially in this context refers to a centrally located longitudinal strip.
Preferably an acrylic plastic plate, called a lens or a refractory grid, comprising a hexagonal series of semi-spherical refractory elements is used. The optical pattern at the bottom side of the lens may consist of a plurality of convex surfaces having a constant radius, and at the upper side said optical pattern may consist of correspondingly concave surfaces. At the upper side prisms are furthermore used for reflecting incident light, whilst at that location a series of essentially curved triangles is provided, which are regularly distributed within the hexagonal series of prisms. Such a lens is marketed by HolophaneR Europe Ltd. under the designation "Controlens 8224".
The light transmission factor of such a lens is about 92%, whereas that of parabolic transverse lamellae is 85% at most. When such a lens according to the invention is used the fixture and lighting efficiency will therefore be higher than with the above-mentioned Dutch Patent Application, because the losses of luminous flux are smaller. The brightness value is lower, since the lens is located higher in the fixture than the brightness determining bottom side of the transverse lamellae in the said Dutch Patent Application; with this lens in particular both in transverse and in longitudinal direction.
In the future lighting fixtures in for example offices will be turned off more often than is the case now, in which case the plates mirroring on one side enhance the aesthetic effect. Thus the architect or the designer, as the case may be, is presented a new tool.
An auxiliary means, such as a flush-mounted halogen lamp, a loudspeaker, a fire or smoke detector, an infrared detector or a wall socket etc. may be provided in the means hiding the light source from view or in an additional, similarly provided auxiliary plate of metal or plastic material.

Claims

A lighting fixture comprising a box-shaped housing having a rectangular bottom plate and a first and a second pair of parallel side plates, said side plates being connected to the bottom plate and defining a rectangular lighting aperture, a lamp holder for an elongated light source secured to the inner side of a respective side plate of said first pair of side plates, and a pair of longitudinal lamellae provided parallel to said second pair of side plates, being spaced from said second pair of side plates, from each other and from the lighting aperture, characterized in that at the upper side of said pair of longitudinal lamellae means are provided which bridge the distance between said second pair of longitudinal lamellae and which hide said light source from view.
A lighting fixture according to claim 1, characterized in that said means hiding the light source from view is selected from metal or plastic grids, prismatic and opal plates, partially diffused acrylate plates and partially diffused plates, mirroring on one side, of glass or plastic material.
A lighting fixture according to claim 1 or 2, characterized in that said means hiding the light source from view is a lens with a hexagonal series of semi-spherical refractory elements having a predetermined optical pattern at its upper and lower sides.
A lighting fixture according to any one of the preceding claims, characterized in that an auxiliary means, such as a flush-mounted halogen lamp, a loudspeaker, a fire or smoke detector, an infrared detector or a wall socket is provided in the means hiding the light source from view or in an additional, similar auxiliary plate.
A lighting fixture according to any one of the preceding claims, characterized in that said longitudinal lamellae have a wedge-shaped cross-section.
A lighting fixture according to any one of the preceding claims, characterized in that the facing parts of said longitudinal lamellae lie at such an angle to vertical that double reflections do not occur.
A lighting fixture according to any one of the preceding claims, characterized in that at their upper sides said longitudinal lamellae are provided with a guide channel for receiving an edge of a plate-shaped means hiding the light source from view.
A lighting fixture according to any one of the preceding claims, characterized in that instead of said longitudinal lamellae means are provided for carrying the means hiding the light source from view.