Luminaire

Abstract: The luminaire has a louvre attachment (5) in the luminous window (2). The louvre attachment is provided with a first and a second reflector (6, 7), which are interconnected by parallel louvre strips (8) which are bent in cross-section into a triangular shape from a strip of sheet material with lateral edges (9). The strips (8) have their seams (10) in the luminous window (2) and the lateral edges (9) lie sideways against one another. The attachment has an even luminance and a luminous window of great effective size.

Description: The invention relates to a luminaire comprising: a housing with a luminous window, means for holding an elongate lamp having a longitudinal direction in said housing along said window and for connecting it to a supply source, which means define said longitudinal direction, a metal louvre attachment in the luminous window comprising a first and a second reflector in the longitudinal direction of the lamp, interconnected by several parallel louvre strips having seams, which strips are bent in cross-section substantially into a triangle from a strip with lateral edge portions, which triangle has its apex in the luminous window and its base in a plane inside the housing remote from the luminous window, and whose legs are curved towards eachother. Such luminaires are generally known. A louvre attachment for such a luminaire is described, for example, in US 4,268,897 and in US 4,429,354. In the known attachments the seam of each louvre strip is in the base of the triangle in the known attachments. This is a logical location because this seam is then invisible, irrespective from which position the luminaire is viewed. It has been found that such attachments can have an uneven luminance, which differs from place to place. This is connected with deviations in shape from one louvre strip to another. It was found that cross-sections of mutually differing shapes also occur in such a louvre strip between its ends. These differences in shape may be caused by differences in strain in the various cross-sections of a louvre strip, but also by inhomogeneities in the material from which louvre strips are formed. The louvre strips do not have an apex angle in the proper sense of the word in their cross-sections, but they are rounded off instead, since bending is only possible with a certain radius of curvature. A disadvantage of this is that the effective size of the luminous window is restricted by the apexes of the louvre strips. The larger the number of strips per unit length of the lamp, the stronger the restriction of the effective size of the luminous window. The effective size of the luminous window is here understood to mean the actual light transmitting opening of this window. It has been found that it is not useful to maximize the effective size of the luminous window by making the louvre strips as thin as possible at their apexes by bending them with a very small radius of curvature. It was in fact demonstrated that the finish of the strips is damaged by this. Paint or gloss layers may develop cracks or even flake-off. Especially gloss layers, such as the oxide skin of anodized aluminium, as a result give a glittering effect which strongly detracts from the quality of the attachment, and thus of the luminaire. CH 539, 239 discloses louvre attachments made of synthetic material. Each louvre strip has a slot with multiple interruptions at its apex so as to form openings through which air may be blown to ventilate the space in which the attachment is used. The invention has for its object inter alia to provide a luminaire of the kind described in the opening paragraph having a louvre attachment of a simple construction in which the luminous window has a great effective size, while nevertheless damage to the finish of the louvre strips in the luminous window is avoided. According to the invention, this object is achieved in that the louvre strips have their seams in the luminous window and in that the lateral edge portions of each louvre strip lie sideways against one another. Thanks to their shape, the louvre strips have a dimension of not more than twice the thickness of the material from which they were formed, measured in longitudinal direction of the lamp at the level of the luminous window. Not only is a louvre strip very thin in this location as a result, and the size of the luminous window very great, but the material is not bent in the luminous window either, so that damage to a reflecting layer, for example an anodized layer, is avoided. Thus the construction is especially suitable for use in luminaires and attachments with optical reflector systems. An important advantage, furthermore, is that the louvre strips need only be folded about lines which lie at a distance from one another, i.e. in order to shape the base of the triangular cross-section. This makes it possible to give the strips an accurate, pre-determined shape, the more so since the lateral edge portions lie sideways against one another. Such an accurate shape could not be realised if the strips, for example, should have had a circularly bent surface remote from the luminous window instead of a surface coinciding with the base of a triangle. In a favourable embodiment, the lateral edge portions bear on one another under pressure for extra stability. This pressure may be generated through elastic deformation in the louvre strip material. The surface remote from the luminous window may give local reflections onto other mirroring surfaces, especially in reflectorizing louvre attachments, for example on the first and the second reflector. In a favourable embodiment, this effect is counteracted by means of several tongues which have been punched from said surface and pressed to the outside. It is favourable if the tongues belong to a first and a second series, which point in mutually opposing directions. The series may be positioned separately or intermixed. These and other aspects of the luminaire according to the invention are described and explained with reference to the drawing. Fig. 1 shows a luminaire in perspective, Fig. 2 shows a cross-section of the louvre attachment taken on the line II-II, Fig. 3 shows a side elevation of a louvre strip, and Fig. 4 shows a cross-section taken on the line IV-IV in Fig. 3. The luminaire of Fig. 1 has a housing 1 comprising a luminous window 2 and means 3 for holding an elongate lamp having a longitudinal direction 4 in said housing 1 along said window 2 and for connecting said lamp to a supply source, the means 3 defining the said longitudinal direction 4. In the Figure, these means 3 are formed by a pair of conventional holders for a straight, tubular low-pressure mercury vapour fluorescent lamp. Alternatively, a U-shaped bent fluorescent lamp or a fluorescent lamp consisting of parallel series-connected closed tube sections could be used in a luminaire of adapted dimensions, the luminaire comprising means suitable for holding and connecting the lamp in question. Alternatively again, the luminaire may be provided with means for accommodating several lamps with the same longitudinal direction. The luminaire has a metal louvre attachment 5 in the luminous window 2. The attachment 5 has (see also Fig. 2) a first 6 and a second reflector 7 in the longitudinal direction 4 of the lamp, which reflectors are interconnected by several parallel louvre strips 8 (see also Fig. 4) having seams 10, which are folded in cross-section into a substantially triangular shape from a strip with lateral edge portions 9. The triangle of the cross-section has its apex 11 in the luminous window 2 and its base in a plane 12 remote from the luminous window inside the housing. Its legs 13 are curved towards eachother. The degree of curvature is immaterial for the nature of the invention and may be very slight or considerable, subject to the optical specification of the luminaire. The louvre strips 8, according to the invention, have their seams 10 in the luminous window 2 and the lateral edge portions 9 of each strip 8 lie sideways against one another. The lateral edge portions 9 bear on one another with pressure through elastic deformation of the louvre strip material, for example anodized aluminium. Several tongues 14 are punched from the surface 12 of the louvre strips 8 remote from the luminous window 2 and bent outwards. The tongues 14 belong to a first series 15 or to a second series 16, which point in mutually opposing directions and are positioned separately.

Claims: A luminaire comprising: a housing (1) with a luminous window (2), means (3) for holding an elongate lamp having a longitudinal direction (4) in said housing along said window (2) and for connecting it to a supply source, which means define said longitudinal direction, a metal louvre attachment (5) in the luminous window (2) comprising a first (6) and a second reflector (7) in the longitudinal direction (4) of the lamp, interconnected by several parallel louvre strips (8) having seams (10), which strips are bent in cross-section substantially into a triangle from a strip with lateral edge portions (9), which triangle has its apex (11) in the luminous window (2) and its base in a plane (12) inside the housing (1) remote from the luminous window, and whose legs (13) are curved toward eachother, characterized in that the louvre strips (8) have their seams (10) in the luminous window (2) and in that the lateral edge portions (9) of each louvre strip (8) lie sideways against one another. A luminaire as claimed in Claim 1, characterized in that the lateral edge portions (9) bear on one another with pressure. A luminaire as claimed in Claim 2, characterized in that the louvre strips (8) have a reflecting layer. A luminaire as claimed in Claim 3, characterized in that the surface (12) of the louvre strips (8) remote from the luminous window (2) have several tongues (14) punched from this surface and bent outwards. A luminaire as claimed in Claim 4, characterized in that the tongues (14) belong to a first (15) and a second series (16) which point in mutually opposing directions.

Inventors: VENDERBOSCH JOSEPHUS WILLIBROR, VENDERBOSCH, JOSEPHUS WILLIBRORD
Applicants: PHILIPS NV, N.V. PHILIPS' GLOEILAMPENFABRIEKEN
Application year: 1990
Main classification: F21V11
IPC codes: F21V11