GB2110810A

GB2110810A - Improvements in lighting units

Info

Publication number: GB2110810A
Application number: GB08229733A
Authority: GB
Inventors: Colin Stanwell-Smith
Original assignee: PA Management Consultants Ltd
Current assignee: PA Management Consultants Ltd
Priority date: 1981-10-15
Filing date: 1982-10-15
Publication date: 1983-06-22
Also published as: GB2110810B

Abstract

A lighting unit for so-called "up- lighting" comprises an opaque tube (10) adapted to be supported at a lower end thereof, e.g. carried by a base (14) which can be fixed to the floor, with the tube directed upwardly. An intense light source and light collimating means e.g. a lens are located within the lower end portion of the tube for directing a parallel beam of light upwardly through the tube. Optical means e.g. a divergent lens is provided at a high level within the tube for modifying the parallel beam to produce ceiling or upper wall illuminating light emergent from the upper end of the tube. <IMAGE>

Description

SPECIFICATION Improvements in lighting units Field ofinvention This invention relates to a lighting unit, more particularly a unit for lighting rooms or similar internal spaces, especially for example in offices and the like.

Background to the invention One type of light which is becoming increasingly important for office lighting is the so-called "uplighter", in which a bright light source such as a high pressure sodium lamp or a metal halide lamp is arranged to direct light upwards on to a ceiling, typically a conventional white ceiling, from which diffused light is reflected around the room. As the lamp is of high intensity, it is conventionally suspended or otherwise situated above normal eye level and shielded, typically by internally reflective shield, from direct line of light.

In many instances it is inconvenient to mount the lamp at this height for such reasons as lack of physical stability, difficulty of cable access, difficulty of maintenance and inappropriate aesthetic design, and it is an object of the present invention to provide a lighting unit for so-called "up-lighting" whereby some or all of the disadvantages of conventional practice can be overcome. It is a further object of the invention to provide an adjustable lighting unit which is adjustable to vary the direction of light emergent therefrom.

The invention According to one aspect of the invention, there is provided a lighting unit which comprises an opaque tube adapted to be supported at a lower end thereof so that the tube is directed upwardly, an intense light source and light collimating means within the lower end portion of the tube for directing a parallel beam of light upwardly through the tube, and optical means at a higher level within the tube for modifying the parallel beam to produce ceiling or upper wall illuminating light emergent from the upper end of the tube.

The light emergent from the upper end of the tube may be, for example, a cone of light, an eccentric cone of light, a fantail beam or diffused light, appropriate means such as lenses, mirrors, diffusers etc. being provided in the path of the parallel beam to produce the desired result.

The tube is preferably adapted for floor mounting at its lower end, and the tube is conveniently carried by a base which can be fixed to the floor. The tube may be mounted to said base on a swivel joint such as a ball and socket joint to enable physical pointing of the tube in a vertical or any chosen upwardly inclined direction.

Hence, in a further aspect of the present invention provides a lighting unit comprising a tube having a light source, a lower end of the tube being mounted via a swivel joint to a base so that the tube is directed upwardly and the angle of inclination of the tube can be adjusted.

Mirrors, lenses, filters or other optical elements, including image tearing slides, possibly holographic slides, may be provided within the tube to modify the colour or distribution of the emergent light or the pattern of images contained therein. A holder may be provided partway along the length of the tube for holding such an element. Furthermore, optical elements such as prisms can be introduced in the side wall of the tube to produce spillage of light, e.g. to provide a task light or similar beam of light for local illumination.

In a practical embodiment, the light source is located below a lens at the focal point thereof, within a generally parabolic reflector which optically closes the lower end portion of the tube, the reflector diverging from its parabolic shape into a central spherical cap below the source and aligned with the lens above the source. The spherical cap will preferably have a chordal diameter equal to the lens diameter and be centred at the focal point of the lens, i.e. at the source. Such an arrangementconsti- tutes an efficient collimating means for producing a parallel beam of light directed upwardly along the tube and filling the cross-section thereof with a satisfactorily uniform distribution throughout said cross-section.A divergent lens at the upper end of the tube can then produce a divergent cone of light for substantially uniformly illuminating a ceiling area.

The invention will be further described, by way of example, with reference to the accompanying drawings.

In the drawings Figure 1 shows a light collimating means at the lower end portion of a tube; Figure 2 shows a light beam modifying means at the upper end of the tube; and Figure 3 diagrammatically illustrates a practical form of lighting unit incorporating the tube.

Detailed description of the drawings Referring first to Figure 3, the lighting unit comprises an opaque tube 10 mounted through a swivel joint 12 to a base 14. The base 14 is intended to be fixed to the floor of the room, enabling the unit to be powered from floor based electrical circuits.

The tube 10 comprises a shield for an optical system within it which will produce ceiling (or possibly upper wall) illuminating light at the upper end of said tube. Such optical system comprises an intense light source, e.g. high pressure sodium or metal halide lamp, together with an optical collimating means, within the lower end portion of the tube, and a light beam modifying means within the upper end of the tube.

As shown in Figure la a convenient collimating means for an intense light source 16 comprises a lens 18 centred on the tube axis above the source, with the latter at the focal point of the lens, and a generally parabolic reflector 20 which optically closes the lower end of the tube 10. The reflector 20 diverges from its parabolic form into a spherical end portion or cap 22 below the source 16. This end portion 22 is spherical up to the lens diameter 24, and is centred on the focal point of the lens 18, i.e.

centred at the source 16. The parabolic form of the reflector 20 outside the lens diameter 24 extends the reflector out to the tube diameter 26.

This arrangement provides a parallel beam of light along the tube, substantially filling the cross-section thereof with a reasonably uniform distribution. The light rays marked in Figure 1 will assist in the understanding ofthe collimating action.

Figure 2 shows the optical modifying means at the upper end of the tube 10. This, in this instance, comprises a simple divergent lens 28 which will produce a divergent cone of light 30 emergent from the upper end of the tube. This divergent cone of light 30 will substantially uniformly illuminate an area of ceiling to reflect light generally around a room.

Figure 2 also serves to show that a mirror 32 and lens 34 may be introduced into the wall of the tube to cast a separate beam of light 36 sideways for a localised illuminating purpose. A prismatic element could be employed instead of the mirror 32 and lens 34.

It will be appreciated that the arrangement shown in the drawings is by way of example only and may be modified in various ways within the scope of the invention hereinbefore described.

Claims

1. A lighting unit comprising an opaque tube adapted to be supported at a lower end thereof so that the tube is directed upwardly, an intense light source and light collimating means within the lower end portion of the tube for directing a parallel beam of light upwardly through the tube, and optical means at a higher level within the tube for, modifying the parallel beam to produce ceiling or upper wall illuminating light emergent from the upper end of the tube.

2. A lighting unit according to claim 1, wherein the tube is adapted for floor mounting at the lower end thereof.

3. A lighting unit according to claim 1 or 2, wherein the tube is carried by a base.

4. A lighting unit according to claims 3, wherein the tube is mounted to the base on a swivel joint.

5. A lighting unit according to claim 4, wherein the swivel joint comprises a ball and socket joint.

6. A lighting unit according to any one of the preceding claims, wherein said optical means comprises a divergent lens at the upper end of the tube.

7. A lighting unit according to any one of the preceding claims, wherein an optical element is provided within the tube to modify the emergent light.

8. A lighting unit according to claim 7, wherein a holder is provided part way along the length of the tube for holding the optical element.

9. A lighting unit according to any one of the preceding claims, wherein an optical element is introduced in the side wall of the tube to produce spillage of light.

10. A lighting unit according to claim 9, wherein the optical element comprises a lens and associated mirror prismatic element.

11. A lighting unit according to any one of the preceding claims, wherein the light source is located below a lens at the focal point thereof, within a generally parabolic reflector which optically closes the lower end portion of the tube, the reflector diverging from its parabolic shape into a central spherical cap below the source and aligned with the lens above the source.

12. A lighting unit according to claims 11, wherein the spherical cap has a chordal diameter equal to the lens diameter and is centred at the focal point of the lens.

13. A lighting unit according to any one of the preceding claims, wherein the light source comprises a high pressure sodium or metal halide lamp.

14. A lighting unit comprising a tube housing a light source, a lower end of the tube being mounted via a swivel joint to a base so that the tube is directed upwardly and the angle of inclination of the tube can be adjusted.

15. A lighting unit according to claim 14, wherein the swivel joint comprises a ball and socket joint.

16. A lighting unit according to claim 14 or 15, wherein the tube is opaque, and comprising an intense light source and light collimating means within the lower end portion of the tube for directing a parallel beam of light upwardlythrough the tube, and optical means at a higher level within the tube for modifying the parallel beam to produce ceiling or upper wall illuminating light emergent from the upper end of the tube.

17. A lighting unit according to claim 14, 15 or 16, wherein said optical means comprises a divergent lens at the upper end of the tube.

18. A lighting unit according to any one of claims 14to 17, wherein an optical element is provided within the tube to modify the emergent light.

19. A lighting unit according to claim 18, wherein a holder is provided partway along the length of the tube for holding the optical element.

20. A lighting unit according to anyone of claims 14 to 19, wherein an optical element is introduced in the side wall of the tube to produce spillage of light.

21. A lighting unit according to claim 20, wherein the optical element comprises a lens and associated mirror or prismatic element.

22. A lighting unit according to any one of claims 14 to 21, wherein the light source is located below a lens at the focal point thereof, within a generally parabolic reflector which optically closes the lower end portion of the tube, the reflector diverging from its parabolic shape into a central spherical cap below the source and aligned with the lens above the source.

23. A lighting unit according to claim 22, wherein the spherical cap has a chordal diameter equal to the lens diameter and is centred at the focal point of the lens.

24. A lighting unit according to any one of the claims 14 to 23, wherein the light source comprises a high pressure sodium or metal halide lamp.

25. A lighting unit substantially as herein described with reference to, and as shown in, the accompanying drawings.