WO1984004796A1

WO1984004796A1 - Light reflector

Info

Publication number: WO1984004796A1
Application number: PCT/GB1984/000182
Authority: WO
Inventors: Christer Skoglund
Original assignee: Christer Skoglund
Priority date: 1983-05-25
Filing date: 1984-05-25
Publication date: 1984-12-06
Also published as: FI850305A0; EP0148865A1; DK35385D0; FI850305L; DK35385A; DE8315374U1; NO850284L

Abstract

A reflector assembly for a UV tube for a sun-bed combines high light-directing efficiency with compact dimensions. A rear reflector (12) has portions (14 to 16') which direct light from rearwardly directed sectors of the tube (11) forward, as shown by rays (30 and 31). A plurality of front reflectors (20 to 23') reflect light from a corresponding plurality of forwardly directed sectors into the forward direction (rays 32 to 35). The front reflectors are also reflective on their rear surfaces, to help reflect forward obliquely emitted radiation (rays 40 and 41). Several such reflector assemblies may be combined into a flat bank, with their axes convergent.

Description

LIGHT REFLECTOR

The present invention relates to light reflectors, and more specifically to light reflectors for use with; fluorescent tubes emitting ultraviolet light. The use of ultraviolet solariums for the artificial tanning of human beings is well known. In a typical solarium, the user lies on a bed which has a UV light fitting above it. The bed itself may be a second UV light fitting, so that the user is exposed to UV light from both above and below; alternatively, the bed may be a simple support, in which case the user will have to turn over to expose both front and back of his or her body. In order to achieve tanning within a reasonable period, typically from several minutes to some tens of minutes, a high intensity of UV light is required, and the or each light fitting therefore includes several UV fluorescent tubes, typically 10. Each of these tubes is normally arranged as a separate cell, with its own reflector for directing the radiation from the tube (which is emitted equally in all directions froom the tube) towards the user.

It is obviously desirable, for efficiency, that the UV light emitted by the fitting or fittings should be largely confined to the space occupied by the user. If the bed itself is a UV light fitting, this is achieved simply by making the size of the bed match the size of the user, since the user lies directly on top of the fitting. In the case of a light source suspended above the bed, the reflectors of the UV emitting tubes direct the light generally downwards, but there is considerable sideways spillage of the light, so the light source is often adjustable vertically so that, when the user is lying on the bed, the light source can be lowered to near the user so as to maximize the light intensity on the user. The main object of the present invention is to provide a reflector, for a UV tube, which achieves a more efficient directing of the light from the tube while keeping the dimensions of the reflector small, so that a substantial number of such reflectors can be arranged side by side. Of course, a conventional parabolic reflector could achieve acceptable light directing, but would in practice be intolerably large in both width and depth. Accordingly the present invention provides a reflector assembly for a fluorescent tube, characterized by the combination of a rear reflector which forwardly reflects light from rearwardly directed sectors of the tube, and, on each side of the tube, a plurality of front reflectors placed between the tube and the reflected beams from the rear reflector and which reflect light from respective forwardly directed sectors of the tube.

Eurther features will be apparent from the subclaims and the following description. A reflector, a modification thereof, and a bank of reflectors in accordance with the invention will now be described, by way of example, with reference to the drawings, in which: Fig. 1 is a cross-section through the reflector; Eig. 1A shows the various radiation sectors of the tube 11 of Eig. 1;

Eig. 2 shows a modification of the reflector of Eig. 1; Eig. 3 is a side view of the complete reflector assembly; a Eig. 4 is a partial cross-section through a bank of reflectors. Referring to Eig. 1, a UV fluorescent tube 11 is shown in cross-section. The reflector comprises an upper structure 12 and four pairs of lower elements 20 to 23, 20' to 23'. The tube 11 emits UV radiation in all directions; we will initially regard the radiation as being emitted largely radially and the radiation in the various angular sectors a to h and back from g' to b' will be discussed shortly. (These sectors are identified by Eig. 1A, which shows the tube 11 and its various sectors in the same orientation as in Eig. 1.) The various structures and elements of the reflector are formed of suitable material, eg of metal of or plastics material coated with reflective metal foil, and are supported by a pair of end members (to be described with reference to Eig. 3) which also provide the connections and support to the ends of the tube 11.

The upper structure 12 is reflective over the whole of its lower surface, and is comprised of 7 main sections; a centre section 13 and three pairs of sections 14 to 16 and 14' to 16' as shown. Sections 16 and 16' are convex inwards, while the other sections are concave inwards; sections 16 and 16' merge smoothly into sections 15 and 15', while sections 14 and 14' meet sections 13, 15, and 15' at, sharp angles. The elements 20 to 23' are all reflective on their forward (inner) surfaces, and are concave inwards. The various angular sectors of the tube 11 are defined by the end-points of the various sections and elements; it will be noted particularly that the four radii defining the sectors d to f are eachr defined by two such points, the elements 15, 16, and 20 to 23 having their end-points aligned to achieve this.

As noted above, we will initially regard the radiation from the tube 11 as emerging largely radially. The various sectors in which the radiation emerges will be considered one by one. Taking first sector a, the raαiation emerging in this sector is reflected directly back into the tube 11 by the portion 13 of structure 12- Much of this returned radiation will be re-emitted in other sectors, and is thus not lost. Taking next sector b, the radiation emerging in this sector falls upon section 14, and is reflected therefrout onto section 16, from which it is reflected a second time into a generally downward direction, as indicated by ray 30, which is a typical ray from scetor b. Radiation emerging in sector b' behaves symmetrically to radiation in sector b, and radiation emerging in sector c behaves symmetrically to radiation in sector c'. Radiation in this latter sector falls upon portion 15' of structure 12, and is reflected therefro substantially directly downwards, as indicated by typical ray 31. The sections 16 and 16' extend far enough to intercept all radiation from sectors b and b' respectively, and the elements 20 and 20' extend just to the edge of the radiation from sectors c and c' after its reflection from sections 15 and 15'.

Radiation emerging from sector d is reflected by element 20, as indicated by typical ray 32; the nsxt element 21 extends just to the edge of this radiation from sector d after its reflection from element 20. Similarly, radiation from sectors e ', f, and g' is reflected by elements 21', 22, and 23' respectively, as shown by typical rays 33 to 35. The sectors d to g and elements 20 to 24 are of course symmetric with sectors d' to g ' and elements 20' to 24'; rays are shown in successive sectors on one side 'and the other of the tube alternately merely to avoid showing too many rays. Elements 22 and 23 just reach the edges of the reflected radiation from sectors e and f respectively.

Finally, radiation from sector h emerges and passes directly fownwards. It is thus apparent that, by means of the various sections of the upper structure 12 and the forward reflectors 20 to 23', the radiation emerging from the tube 11 is divided into a large number of relatively narrow sectors, and the radiation from each of these sectors (except that in sector a) is separately directed downwards. Thus the angular width of the resulting combined beam may be made very small. Further, by adjusting the individual reflecting sections and elements, the distribution of the radiation in the resulting beam may be adjusted as desired, eg to be substantially uniform across the whole angular width of the beam.

The curvature of the reflectors is chosen so that the intensity of the radiation is substantially uniform at the region that the user will occupy. This may be achieved either by arranging for the beam of each sector to cover the whole of the area to be lit, or by arranging for the beams to light adjacent strips of the area.

The structure 12 may be constructed so that the two portions 14 and 14' meet, so that portion 13 and angular sector a become non-existent.

It will however be realized that the radiation emerging from the tube 11 does not all emerge radially, but much emerges at oblique angles to the surface of the tube 11. Two means are provided to minimize the potential loss of this non-radial radiation.

First, the portions 16 and 16' of the structure 12 extend below the lower boundaries of sectors c and c'. These portions may in fact be extended, downwards so that their lower ends are substantially in line with the lines tangent to the tube 11 and grazing the lower ends of the elements 20 and 20'. Alternatively the upper ends of the elements 20 and 20' can be moved to points above the horizontal line through the centre of the tube, and the portions 16 and 16 ' need not then extend so far downwards. This means that some of the oblique radiation from the sectors b to c' is intercepted by these two portions 16 and 16', as indicated by typical oblique ray 40. Of course, other oblique radiation in these sectors will be reflected by portions 14 to 15' (or portions 14 and 16, or 14' and 16'). In addition, some of the oblique radiation from these sectors will return to the tube 11 after two or more reflections, as shown by ray 42. This radiation will be absorbed and largely re-emitted, like the radiation from sector a. Thus there will be very little loss of oblique radiation from the sectors b to c'. Second, the upper (ie outer) surfaces of the elements 20 to 23' are also reflective. This means that oblique radiation in sectors d to g' is also likely to be reflected forward, either by a single reflection on the forward (inner) surface of one of these elements, or by a first reflection on the outer surface of one of these elements and a second reflection on the inner surface of the adjacent element, as indicated by typical oblique ray 41 in sector e. Some of the oblique radiation reflected from the outer surface of element 21 will be reflected again from the portion 16.

The portions 16 and 16' may have strenthening flanges 17 and 17' formed at their outer ends. Fig. 2 shows an improved form of the reflector, in partial and enlarged form. The general arrangement is as in Eig. 1, with two of the four adjacent forward reflectors being shown adjacent to a. portion of the tube 11. It will be seen that element 51 has its front surface curved in the manner of the elements 20 to 23 of Fig. 1. Element 51 is however not of uniform and small thickness, Instead, its outer surface 51b is formed with a different curvature to the inner surface 51a, so as to achieve a better gathering and directing of the oblique radiation falling on it and reflected onto the inner surface of element 50 for a second reflection in the forward direction. The curvature of surface 51b may be either concave upwards or convex but of different curvature (either greater or less) from surface 51a. Fig. 3 is a side view of a complete reflector 10.

As shown, the assembly comprises two end members 60 and 60' which support the ends of the tube 11 and the reflectors 12 and 20 to 23'.

As stated above, it is common to provide a bank of several tubes and reflectors placed side by side. Obviously, the reflectors may be in a common plane (usually horizontal), which would give a somewhat uneven distribution of the combined beams, with greater strength at the middle and reducing towards the edges. The reflectors may also be arrange in an arc of a circle, as is also well known. Fig. 4 indicates a further possible arrangement, in which the reflectors are arranged in a common plane but in which the uniformity of the resultant combined beam is kept high. This is achieved by arranging adjacent reflectors 10-1 to 10-4 so that their beams converge at the position 71 where the user will lie, as indicated by the axes 70-1 to 70-4 of these beams. The reflectors are preferably essentially identical, with adjacent reflectors fitting together by means of slight adjustments to the instances by which. the portions 16-1, 16 '-2, etc extend, or the ends of these portions may be staggered slightly. Alternatively, the reflectors may be designed asymmetrically.

Claims

C LA IMS

1. A reflector assembly for a fluorescent tube, characterized by the combination of a rear reflector (12) which forwardly reflects light from rearwardly directed sectors (b to c') of Tine tube (11), and, on each side of the tube, a plurality of front reflectors (20 to 23') placed between the tube and the reflected beams from the rear reflector and which reflect light from respective forwardly directed sectors (d to g, d' to g ') of the tube.

2. A reflector assembly, according to claim 1, characterized in that the forward reflectors (20 to 23') are also reflective on their outer sides.

3. A reflector assembly according to claim 2, characterized in that the rear surfaces of the forward reflectors are of different curvature to their front surfaces.

4. A reflector assembly according to any previous claim, characterized in that the rear reflector has a pair of portions (14, 14') which reflect light from extreme rearward sectors (b, b') of the tube (11) onto further portions (16, 16') of the rear reflector for a second reflection into the forward direction. assembly

5. A reflector/according to any previous claim, characterized in that the rear reflector extends to substantially the lines tangent to the tube and grazing the lower ends of the outermost pair of front reflectors.

6. A reflector assembly according to any previous claim, characterized in that the rear reflector (12) has a centra portion (13) which reflects light directly back into the tube.