EP0619454B1

EP0619454B1 - Louvre for a luminaire and luminaire provided therewith

Info

Publication number: EP0619454B1
Application number: EP19940200863
Authority: EP
Inventors: Jacques C/O Int. Octrooibureau B.V. Sergent; Olivier C/O Int. Octrooibureau B.V. Gaillot
Original assignee: Koninklijke Philips Electronics NV; Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 1993-04-07
Filing date: 1994-03-30
Publication date: 1997-06-18
Anticipated expiration: 2014-03-30
Also published as: EP0619454A1

Description

The invention relates to a louvre for use in the light emission window of a luminaire, comprising:

an inner circumferential reflector having an axis and an inner surface concavely curved along this axis;
an outer circumferential reflector having an outer surface concavely curved along the axis, which outer reflector is coupled to the inner reflector;
lamellae fastened to the outer reflector and extending away from the axis. The invention also relates to a luminaire provided with this louvre.

A luminaire provided with such a louvre is known from DE 38 26 676 A1.
The known luminaire is designed for compact fluorescent lamps. The function of the louvre is to prevent the luminaire, mounted against or in a ceiling, from radiating light at great angles to the perpendicular and thus causing, for example, reflections on display screens and on work surfaces in the illuminated room.
The inner reflector of the known louvre is parabolically curved and has an outwardly projecting collar at both its ends. The outer reflector is also parabolically curved and rests on one of these collars, while gripping behind the other collar with plate springs fastened to this reflector. The lamellae are parabolically curved, V-shaped, in cross-section. They are fastened to the outer reflector with screws.
The construction of the known louvre has a number of disadvantages. A large number of components is required for assembling the louvre. This is one of the reasons why the assembly requires comparatively much time and the manufacture of the louvre is logistically complicated. The outwardly projecting collar on which the outer reflector rests intercepts light, which is thrown back sideways and thus is removed from the beam to be formed. The other outwardly projecting collar, behind which the plate springs grip, causes reflections in the luminaire, whereby locally undesirable increased brightnesses arise on portions of the luminaire, which detract from the homogeneity of the beam to be formed and from the comfort offered by the illumination.
It is an object of the invention to provide a louvre of the kind described in the opening paragraph, as well as a luminaire provided therewith, which is of a simple construction which can be easily realised.
According to the invention, this object is achieved in that

the outer reflector has a rim bent back upon itself on which the inner reflector rests with a shoulder thereof, and
the two reflectors are kept in position relative to one another by the lamellae.

It is an attractive feature of the louvre according to the invention that an outwardly projecting collar which intercepts light and throws it outside the beam is avoided. Also avoided is a second collar which may cause additional reflections in a luminaire. Furthermore, no additional locking elements such as plate springs are necessary. The louvre accordingly is of a high quality, while nevertheless its assembly is easy and logistically simple.
The lamellae may project through the outer reflector, for example with tags and a tongue at these lamellae, and be fastened thereto, for example, in that these tags are bent behind this reflector or in that they snap behind this reflector. The tongue may extend through the inner reflector and thus prevent this reflector from working loose from its seat on the bent-back rim.
An attractive construction, however, is that in which the lamellae project through the outer reflector and bear on the shoulder of the inner reflector. This construction has the advantage that the inner reflector remains undamaged and shows no betraying signs of its fastening at its reflecting surface.
The lamellae may be flat strips, but in a favourable embodiment they are substantially V-shaped, having a bottom and legs.
The lamellae may be fastened to the outer reflector in various ways, for example, without additional components being used for this. In that case, openings are present in the outer reflector into which the lamellae are hooked. Such fastenings are known, for example, from rectangular louvre attachments for luminaires. In that application, transverse slats may be fastened to side reflectors or to longitudinal lamellae, or to longitudinal reflectors placed between the ends of the lamellae.
EP 0 491 428 A1 discloses inter alia a construction in which ears present at the lamellae project through openings in a reflector and are fixed therein by snap connections.
Another fastening known from this EP Application is one in which the reflector has an opening with tongues projecting into this opening, while each lamella has a slot in the bottom of its V into which a boundary of the opening enters, and openings in their legs into which respective tongues grip with locking action.
In a particularly secure construction, the lamellae each have a slot in the bottom of the V and at a distance therefrom tongues, while the outer reflector has openings. The lamellae project into respective openings, have a boundary thereof enclosed in the slot, and project with their tongues through the opening with locking action. The tongues are bent back, for example, behind the reflector.
In a favourable embodiment, the reflectors are each curved in accordance with a curve of a degree higher than two. It was found that a particularly good screening is obtained thereby, and the light beam is cut off already at comparatively small angles to the axis, so that the luminance above that angle is below 200 cd/m². In a favourable modification thereof, the legs of the lamellae are concavely curved in accordance with the arc of a circle at their outer surface.
It was found to be advantageous to make the convex sides of the reflectors light-absorbing, for example, a dull black. Furthermore, it is advantageous also to give the mutually facing, for example convex sides of the legs of the lamellae such a finish. Parasitic radiation can then be avoided. For easy fastening to a luminaire, the lamellae have free-end portions with recesses, for example, opposite the bottom of the V in the case of substantially V-shaped lamellae.
The luminaire according to the invention has a concave circumferential main reflector with a light emission window and at a distance from that window means for accommodating at least one electric lamp. The luminaire is provided with a louvre according to the invention.
In a special embodiment, the luminaire comprises a ring around the light emission window, and the louvre is accommodated with the free-end portions of the lamellae between the main reflector and the ring.
Embodiments of the louvre and the luminaire according to the invention are shown in the drawing, in which

Fig. 1 shows a luminaire in axial cross-section with a louvre in side elevation;
Fig. 2 a is an axial cross-section of the louvre of Fig. 1;
Fig. 2 b is a cross-section taken on the line IIb in Fig. 2 a;
Fig. 2 c shows the outer reflector of Fig. 1 in axial cross-section;
Fig. 2 d is a side elevation of the lamella of Fig. 2 a;
Fig. 3 shows a modification of Fig. 2 c with a lamella in cross-section; and
Fig. 4 shows a modification of Fig. 2 a.

In Fig. 1, the luminaire has a concave circumferential main reflector 31 with a light emission window 32 and, at a distance from that window, means 33 for accommodating an electric lamp, in the Figure three lampholders of which two are visible, each suitable for accommodating, for example, a compact fluorescent lamp. The luminaire has a louvre 1 in its light emission window 32.
The louvre 1 has an inner circumferential reflector 2 with an axis 3 and an inner surface 4 concavely curved along this axis. An outer circumferential reflector 12 with an outer surface 14 concavely curved along the axis 3 is coupled to the inner reflector 2. Lamellae 20 extending away from the axis 3 are fastened to the outer reflector 12.
The outer reflector 12 [Fig. 2 a] has a rim 15 which is bent back upon itself and on which the inner reflector 2 rests with a shoulder 5 thereof. The two reflectors 2, 12 are kept in position relative to one another by the lamellae 20. The inner reflector 2 is self-centring on the outer reflector 12 owing to a cylindrical portion 5' present at the former reflector.
The lamellae 20 project through the outer reflector 12 and bear on the shoulder 5 of the inner reflector 2. They could, if so desired, alternatively rest on the convex surface 9 of this reflector so as to centre this reflector.
Openings 16, into which the lamellae 20 are hooked, are present in the outer reflector 12 [Fig. 2].
The lamellae 20 [Fig. 2 b] are substantially V-shaped with a bottom 21 and legs 22. They each have a slot 23 [Fig. 2 d] in their bottom 21 in which a boundary of an opening 16 in the outer reflector 12 is accommodated, as well as tongues 24 which grip through this opening with locking action. The tongues could be snapped into the reflector. In the embodiment shown, they lie in the opening with clamping fit. One of the tongues 24 has already been bent back behind the reflector 12. The opening 16 has narrowed portions 16' where the legs of the lamellae are accommodated with their free edges. These portions render it impossible for the tongues to lose their grip behind the reflector.

Fig. 2 a shows that none of the

reflectors

2, 12 restricts the passage of light from the other reflector.

Table 1

y	x reflector 2	x reflector 12
0	59	64
5	58,9	64,09
10	58,81	64,19
15	58,73	64,27
20	58,61	64,38
25	58,34	64,66
30	58,02	64,98
35	57,67	65,32
40	57,28	65,71
45	56,86	66,14
50	56,38	66,62
55	55,85	67,14
60	55,22	67,77
65		68,57

The reflectors 2, 12 are curved in accordance with a curve of a degree higher than 2, as shown in Table 1. The legs 22 of the lamellae 20 are substantially circularly concavely curved at their outside 25.
The reflectors 2, 12 are light-absorbing at their convex sides 9, 19 [Fig. 2 a], as are the mutually facing sides 29 of the legs 22 of the lamellae 20.
The lamellae have free-end portions 26 with recesses. In Fig. 1, a ring 34 is present around the light emission window 32, and the louvre 1 is accommodated with the free-end portions 26 of the lamellae 20 between the ring 34 and the main reflector 31. The ring is fixed, for example, with a clamp or with a bayonet coupling.
In Fig. 3, reference numerals are 100 higher than those in Figs. 1 and 2. The legs 122 of the lamella contain openings 128 into which tongues 118, which project into the opening 116 of the outer reflector 112 in forward direction, grip with locking action.
In Fig. 4, reference numerals are 200 higher than those in Figs. 1 and 2. The lamella 220 has tags 224 which are snapped into an opening 216 in the outer reflector 212. A tongue 215' is present at the edge 215 of this reflector, which tongue projects through the shoulder 205 of the inner reflector 202.

Claims

A louvre for use in the light emission window of a luminaire, comprising:
an inner circumferential reflector (2) having an axis (3) and an inner surface (4) concavely curved along this axis;

an outer circumferential reflector (12) having an outer surface (14) concavely curved along the axis (3), which outer reflector (12) is coupled to the inner reflector (2);

lamellae (20) fastened to the outer reflector (12) and extending away from the axis (3),

characterized in that the outer reflector (12) has a rim (15) bent back upon itself on which the inner reflector (2) rests with a shoulder (5) thereof, and

the two reflectors (2, 12) are kept in position relative to one another by the lamellae (20).
A louvre as claimed in Claim 1, characterized in that the lamellae (20) project through the outer reflector (12) and bear on the shoulder (5) of the inner reflector (2).
A louvre as claimed in Claim 1 or 2, characterized in that openings (16) are present in the outer reflector (12) into which the lamellae (20) are hooked.
A louvre as claimed in Claim 1, 2 or 3, characterized in that the lamellae (20) are substantially V-shaped, having a bottom (21) and legs (22).
A louvre as claimed in Claim 4, characterized in that the lamellae (20) each have a slot (23) in the bottom (21) in which a boundary of an opening (16) in the outer reflector (12) is accommodated, as well as tongues (24) which grip through said opening with locking action.
A louvre as claimed in Claim 5, characterized in that the tongues (24) are bent back behind the reflector (12).
A louvre as claimed in any one of the preceding Claims, characterized in that the reflectors (2, 12) are each curved in accordance with a curve of a degree higher than 2.
A louvre as claimed in Claim 4, characterized in that the legs (22) of the lamellae (20) are concavely curved substantially along the arc of a circle at their outer surface.
A louvre as claimed in Claim 1 or 7, characterized in that the reflectors (2, 12) are light-absorbing at their convex sides (9, 19).
A louvre as claimed in Claim 4 or 9, characterized in that the lamellae (20) are light-absorbing at the mutually facing sides (29) of the legs (22).
A louvre as claimed in Claim 1, 4 or 7, characterized in that the lamellae have free-end portions (26) with recesses.
A luminaire provided with a concave circumferential main reflector (31) having a light emission window (32) and at a distance from that window means (33) for accommodating an electric lamp,
characterized in that the luminaire has a louvre (1) as claimed in any one of the preceding Claims in its light emission window (32).
A luminaire as claimed in Claim 12, characterized in that a ring (34) is present around the light emission window (32), and the louvre (1) is accommodated with the free-end portions (26) of the lamellae (20) between the ring (34) and the main reflector (31).