GB2261279A - Light fitting - Google Patents
Light fitting Download PDFInfo
- Publication number
- GB2261279A GB2261279A GB9122340A GB9122340A GB2261279A GB 2261279 A GB2261279 A GB 2261279A GB 9122340 A GB9122340 A GB 9122340A GB 9122340 A GB9122340 A GB 9122340A GB 2261279 A GB2261279 A GB 2261279A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- directing means
- concentrator
- light guide
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
- G02B6/0006—Coupling light into the fibre
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
- G02B6/0008—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type the light being emitted at the end of the fibre
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Planar Illumination Modules (AREA)
Abstract
A light fitting is provided comprising an elongate light guide (10) attached to a housing (16) within which is mounted a light source. Light from the light source is directed into the light guide (10) by directing means such as a non-imaging concentrator (12). At the output end of the light guide (10) further light directing means (14) may be provided to direct or dispense emerging light rays. The light fitting may be free standing or wall/ceiling mounted and the light guide (10) may be formed as a smoothly contoured aesthetically pleasing shape. <IMAGE>
Description
LIGHT FITTING
The present invention relates to light fittings and lamps which may be wall or ceiling mounted or free standing. Such lamps and light fittings will be referred to generically hereinafter as light fittings.
In accordance with a first aspect of the present invention there is provided a light fitting including a light source, an elongate light guide capable of transmitting light incident on a first end thereof and of radiating such transmitted light from a second end thereof, and first light directing means positioned relative to the said first end and the light source and shaped to direct light emitted from the light source onto the said first end, the first light directing means including a non-imaging concentrator positioned between the light source and the said first end.
The concentrator may be a hollow body having a reflective inner surface, or may be a solid body of light transmitting material with light being internally reflected. Where the concentrator is a solid body of light transmitting material it may be a separate unit attached to the said first end of the light guide, or the concentrator and light guide may be a unitary body of light transmitting material. The concentrator is a generally frustoconical body which is preferably shaped such that substantially all rays of light entering the concentrator from the light source will be reflected no more than once within the concentrator before entering the light guide.
In accordance with a second aspect of the present invention there is provided a light fitting including a light source, an elongate light guide capable of transmitting light incident on a first end thereof and of radiating such transmitted light from a second end thereof, first light directing means positioned relative to the said first end and the light source and shaped to direct light emitted from the light source onto the said first end, and second light directing means positioned relative to the second end of the light guide and shaped to direct light radiated therefrom.
The second light directing means may be a body of light transmitting material attached to the second end of the light guide or formed as a unitary body with the light guide. A light fitting according to the first aspect of the present invention may also be provided with such second light directing means. Additionally, the first light directing means of a light fitting according to the second aspect of the present invention may include a non-imaging concentrator positioned between the light source and the first end of the light guide.
The first light directing means may include a reflective body, such a parabolic, elliptical, or faceted reflector, positioned relative to the light source to reflect light emitted thereby onto the said first end of the light guide.
The light guide itself may be a length of light transmitting material such as glass or transparent acrylic resin, for example
Perspex (registered trade mark). The light guide may be formed as a smoothly contoured aesthetically pleasing shape, such as a simple curve or more complex spiral The external surface of the light guide, other than the first and second ends, may be covered by a layer of transparent material - suitably a fluoropolymer having a low refractive index. Such a fluoropolymer coating may be provided either as a layer deposited on the surface of the light guide or as a sleeve which is heat shrunk onto the light guide.
The light guide may alternatively be formed as an at least partially flexible body, suitably having a core of gel-like light transmitting acrylic material surrounded by a protective shroud of polytetrafluoroethane. The at least partial flexibility allows the light guide to be shaped by the user in like manner to a goose neck support.
Between the light source and the end of the light guide (or non-imaging concentrator when provided) a heat filter, or 'hot mirror', may be provided. Such a heat filter would be substantially transparent to visible light whilst largely reflective to infra-red light and would thus protect the light guide or concentrator from some of the heat generated by the light source.
One particular use for which the light fitting of the present invention is suited is as a picture light, that is to say a light attached to or adjacent to a picture which light fitting is configured to direct its light to illuminate the picture. The light fitting of the present invention has the particular advantage that the point at which light is emitted, that is to say the second end of the light guide, is distant from the light source, such that the heat generated by the light source may be kept distant from the picture. Furthermore, the ultra-violet and infra-red components (where not already blocked by a heat filter as described above) of light emitted from the light source, which components may be harmful to the picture, will tend to be absorbed in the material of the light guide.
Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:
Figure 1 shows a side elevation of a first embodiment of light fitting according to the present invention;
Figure 2 is an end view of the lamp housing of the light fitting of figure 1, in the direction indicated by II in figure 1 and with the lamp omitted;
Figure 3 is a plan view of the underside of the base of the light fitting of figure 1;
Figure 4 is a sectional view through the light source housing of the light fitting of figure 1;
Figure 5 schematically illustrates the path of light rays emitted from the light source in figure 4;
Figure 6 is a sectional view through a light source housing according to a second embodiment of the present invention;;
Figure 7 schematically illustrates the path of light rays exiting from the end of the light guide in the light fitting of figure 1;
Figures 8 to 15 show a number of alternative configurations of light directing body provided at the end of the light guide from which light exits; and
Figure 16 schematically illustrates the operation of a heat filter.
Referring initially to figure 1, a first embodiment of light fitting according to the present invention comprises a light guide 10 having first 12 and second 14 light directing means at respective ends thereof, a lamp housing 16 to which the first light directing means 12 is attached, and a base 18 to which the lamp housing 16 is attached by a swivel mount 20. The light guide 10 is formed from an acrylic or polycarbonate rod or other optically clear refracting medium, suitably a cast acrylic manufactured by
ROHM. The first 12 and second 14 light directing means may be formed integrally with the light guide 12 or may be provided as separate units with an airgap or cemented interface: it has been found that between 5 and 10 percent of transmitted light is lost at each such join.
The shape of the light guide 10 shown in figure 1, having a substantially straight portion curving at one end thereof, is not an essential feature of the invention. Other shapes of light guide, such as spirals or other arrangements of curved and straight portions, may be provided.
As shown in figure 2, the attachment of the first light directing means 12 to the lamp housing 16 comprises three threaded steel support pins 22 extending through threaded apertures in the lamp housing 16 to engage the outer surface of the first light directing means 12.
The base 18 of the light fitting is a plate of alloy material which may be of any desired shape, one example of which is shown in figure 3. The base 18 is provided with rubber or plastic feet 24.
The lamp housing 16 and swivel mount 20 are shown in greater detail in figure 4. The lamp housing 16 comprises a generally cylindrical alloy or injection moulded high temperature plastics body, the inner surface of which may be coated with a layer of light reflective material. The lamp housing 16 contains a ceramic lamp holder 26 in which is mounted a lamp 28. The lamp 28 is suitably a 35 mm diameter reflecter dichroic quartz hallogen lamp rated 12 watts at 12 volts a.c. (type M64) or 20 watts at 12 volts a.c.
(type M62). A suitable aperture is provided in the lamp housing to allow the passage of a power supply cable to the lamp holder 26, and the outer surface of the housing 16 is provided with radial fins 17 to disperse heat from the lamp 28.
The swivel mount 20 comprises a pair of aligned parallel circular plates 30,32 separated by a rubber friction pad 34. A locking bolt 36 passes through a clearance opening 38 in one of the plates 30 and the friction pad 34 and engages a threaded bore 40 in the other of the plates 32. Loosening of the locking bolt 36, by means of knob 42, allows the plates 32 to rotate relative to one another.
The first of the plates 30 has a radial bore 44 which receives one end of a shaft 46, the shaft 46 being retained by a locking screw 48. The other end of the shaft 46 threadably engages a bore in a strut 47 (fig. 2) across the rear of the lamp housing 16, thereby attaching the lamp housing to the first plate 30. The second plate 32 is also provided with a radial bore 50 receiving one end of a shaft 52, which shaft is retained by a locking screw 54. The other end of this second shaft 52 is rotably attached to the base 18 , as shown in figure 1.
Referring now to figure 5, the operation of the first light directing means 12 to direct light emitted by the lamp 28 into the light guide 10 is schematically illustrated. The first light directing means 12 comprises a non-imaging concentrator in the form of a substantially frustoconical body of light transmitting material shaped to direct, by total internal reflection, light rays incident onto a first end 12a of large surface area to a second end 12b of smaller surface area at which second end 12b the emerging light rays enter the light guide 10. The outer surface of the concentrator may have a degree of curvature as shown or may be straight sided (as in the embodiment of figure 16).In order to operate efficiently, the outer surface of the concentrator is configured such that substantially all light rays 64 from the lamp 28 incident on the first end 12a of the concentrator will be internally reflected no more than once before emerging from the second end 12b of the concentrator. A maximum angle for deviation of light rays from the optical axis in the light guide 10 is specified: a suitable maximum value is 300. With collimated light entering the first end 12a of the concentrator shown (that is to say with a curved outer surface), the most steeply tapered portion of the outer surface of the concentrator, adjacent the second end 12b, must therefore be tapered at an angle of 150 or less with respect to the optical axis.The curvature of the remainder of the outer surface of the concentrator, towards the first end 12a, is calculated in known manner to direct all rays parallel with the optical axis towards the centre of the second end 12b.
Additionally, an amount of non-collimated (off-axial) light incident on the first end 12a will be transmitted to the second end 12b, which amount may be increased by covering the outer surface of the concentrator with a coating of light reflecting material. The curvature of the outer surface of the concentrator 12 is, in a preferred embodiment, calculated with reference to incident collimated light only.
In an alternative embodiment (not shown) the non-imaging concentrator is omitted and the first light directing means comprises an elliptical, parabolic, or faceted reflector with trapezoidal or honeycomb facets, which acts to direct light emitted by the lamp onto the end of the light guide. In a further embodiment, the reflector is used in combination with the non-imaging concentrator.
An alternative form of non-imaging concentrator, replacing the solid concentrator shown in figure 5, is illustrated in figure 6.
The concentrator of figure 6 comprises a hollow body 56 of aluminium or alloy material having a highly polished interior surface 58 shaped to direct light rays emitted by the lamp 28 into the end of the light guide 10. The shape of the polished interior surface 58 is calculated in the same manner as described above with reference to the outer surface of a concentrator 12 formed as a solid body of light transmitting material and, as mentioned above, the reflecting surface may be straight or may have a degree of curvature. As with the housing 16 of figure 4, the outer surface of the hollow body 56 is provided with radial fins 60 to disperse heat radiated by the lamp 28.
The path of light rays exiting from the end of the light guide 10 is illustrated schematically in figure 7. At the end of the light guide 10, second light directing mean 14 may be provided to direct or disperse the emerging light rays. The second light directing means 14 is a body of light transmitting material which may be shaped in any desired form, examples of which are shown in figures 7 to 15. As shown the end surface 15 of the second light directing means 14 may be a flat (figs. 7 to 9), convex (figs. 11, 12) or concave (figs. 10, 13 to 15) surface. Similarly, the outer surface 13 of the second light directing means 14 may be straight (figs. 8, 12 to 14), convex (figs. 7, 10, 11 and 15) or concave (fig. 9).It will be appreciated that the shape of the second light directing means 14 is not limited to the embodiments shown and that a large number of alternative shapes are possible.
In a further alternative embodiment, the second light directing means 14 may comprise a body of light reflecting material, two possible configurations of which are as shown in figures 14 and 15.
The second light directing means may be a unitary body with the light guide 10, as shown in the examples of figures 7 to 11, or it may be a separate body attached to the end of the light guide 10, as shown in the examples of figures 12 to 15. The light fitting of one aspect of the present invention may be provided without the second light directing means 14. Alternatively, the second light directing means 14 may be made removable such that a set of different shapes of second light directing means 14 may be provided for use with the light fitting of the present invention, with the user selecting whichever shape may be desired for any particular application.
The outer surface of the light guide 10 is coated with a layer of material of lower refractive index than the material of the light guide. The coating material is preferably transparent and may be provided by deposition on the outer surface of the light guide 10 or it may be provided as a sleeve which is heat-shrunk when in position. Where provided, the outer surfaces of the solid concentrator 12 and/or second light directing means 14 may be similarly coated.
The low refractive index of the coating causes the majority of light passing along the light guide to be totally internally reflected within the light guide. Minor damage to the light guide by scratching or abrasion will therefore affect only the outer surface of the coating material and will not affect the total internal reflection of light within the light guide. An additional coating of opaque material may be provided over the transparent coating if desired.
As shown in figure 16 (which also shows a non-imaging concentrator having a substantially straight reflecting surface), a heat filter 66 or 'hot mirror' may be provided between the light source 28 and the concentrator 12. The heat filter 66 is a plate of dichroic filter material which appears transparent to visible light 68 whilst reflecting infra-red light 70. The use of the heat filter 66 provides protection for the concentrator 12 (or light guide 10 where the concentrator is omitted) from some of the heat generated by the light source 28. This is of particular benefit where high powered lamps are desired to be used which might otherwise damage the concentrator and/or light guide.
Claims (22)
1. A light fitting including a light source, an elongate light guide capable of transmitting light incident on a first end therof and of radiating such transmitted light from a second end thereof, and first light directing means positioned relative to the said first end and the light source and shaped to direct light emitted from the light source onto the said first end, the first light directing means including a non-imaging concentrator positioned between the light source and the said first end.
2. Apparatus according to claim 1, including a heat filter positioned between the light source and the first light directing means.
3. A light fitting including a light source, an elongate light guide capable of transmitting light incident on a first end thereof and of radiating such transmitted light from a second end thereof, first light directing means positioned relative to the said first end and the light source and shaped to direct light emitted from the light source onto the said first end, and second light directing means positioned relative to the second end of the light guide and shaped to direct light radiated therefrom.
4. Apparatus according to claim 3, including a heat filter positioned between the light source and the said first end.
5. Apparatus according to claim 3, in which the first light directing means includes a non-imaging concentrator positioned between the light source and the said first end.
6. Apparatus according to claim 1 or claim 5, in which the concentrator is a hollow body having reflective inner surface.
7. Apparatus according to claim 1 or claim 5, in which the concentrator is a solid body of light transmitting material.
8. Apparatus according to claim 7, in which the concentrator and light guide are a unitary body of light transmitting material.
9. Apparatus according to claim 1 or claim 5, in which the concentrator is so shaped that substantially all light rays entering the concentrator from the light source will be reflected within the concentrator no more than once before entering the light guide.
10. Apparatus according to claim 1, including second light directing means positioned relative to the said second end of the light guide and shaped to direct light radiated therefrom.
11. Apparatus according to claim 3 or claim 10, in which the second light directing means is a body of light reflecting material.
12. Apparatus according to claim 3 or claim 10, in which the second light directing means is a body of light transmitting material.
13. Apparatus according to claim 12, in which the second light directing means and light guide are a unitary body of light transmitting material.
14. Apparatus according to claim 3 or claim 10, in which the second light directing means is removably attached to the said second end of the light guide.
15. Apparatus according to any of claims 1 to 4, in which the first light directing means includes a reflective body positioned relative to the light source to reflect light emitted thereby.
16. Apparatus according to claim 15, in which the light reflective body is a parabolic reflector.
17. Apparatus according to claim 15, in which the light reflective body is an elliptical reflector.
18. Apparatus according to claim 15, in which the light reflective body is a facetted reflector.
19. Apparatus according to any preceding claim, in which at least a part of the exernal surface of the light guide, other than the first and second ends, is covered by a layer of material having a lower refractive index than the material of the light guide.
20. Apparatus according to any of claims 1 to 4, in which the light guide is at least partially flexible.
21. A light fitting substantially as hereinbefore described with reference to figures 1 to 5 of the accompanying drawings.
22. A light fitting substantially as hereinbefore described with reference to figure 6 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9122340A GB2261279A (en) | 1991-10-22 | 1991-10-22 | Light fitting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9122340A GB2261279A (en) | 1991-10-22 | 1991-10-22 | Light fitting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9122340D0 GB9122340D0 (en) | 1991-12-04 |
| GB2261279A true GB2261279A (en) | 1993-05-12 |
Family
ID=10703296
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9122340A Withdrawn GB2261279A (en) | 1991-10-22 | 1991-10-22 | Light fitting |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2261279A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0610033A1 (en) * | 1993-02-01 | 1994-08-10 | General Electric Company | Collection optics for high brightness discharge light source |
| WO1997001728A1 (en) * | 1995-06-29 | 1997-01-16 | Siemens Components, Inc. | Localized illumination using tir technology |
| GB2317241A (en) * | 1996-09-12 | 1998-03-18 | Schott Fibre Optics | Fibre optic cable passanger seat lighting |
| US5785404A (en) * | 1995-06-29 | 1998-07-28 | Siemens Microelectronics, Inc. | Localized illumination device |
| WO1999010864A1 (en) * | 1997-08-25 | 1999-03-04 | Lewis Gordon C | System for lighting overhead highway signs from a remote light source |
| GB2379497A (en) * | 2001-09-07 | 2003-03-12 | Visteon Global Tech Inc | Optical illuminator with heat dissipation |
| WO2005106322A1 (en) * | 2004-04-16 | 2005-11-10 | 3M Innovative Properties Company | Luminous elongate device with a light fibre and a light injector |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2184220A (en) * | 1984-09-27 | 1987-06-17 | Gary J Thompson | Decorative light display |
| GB2192268A (en) * | 1985-12-17 | 1988-01-06 | Agency Ind Science Techn | Light source unit |
-
1991
- 1991-10-22 GB GB9122340A patent/GB2261279A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2184220A (en) * | 1984-09-27 | 1987-06-17 | Gary J Thompson | Decorative light display |
| GB2192268A (en) * | 1985-12-17 | 1988-01-06 | Agency Ind Science Techn | Light source unit |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0610033A1 (en) * | 1993-02-01 | 1994-08-10 | General Electric Company | Collection optics for high brightness discharge light source |
| WO1997001728A1 (en) * | 1995-06-29 | 1997-01-16 | Siemens Components, Inc. | Localized illumination using tir technology |
| US5775792A (en) * | 1995-06-29 | 1998-07-07 | Siemens Microelectronics, Inc. | Localized illumination using TIR technology |
| US5785404A (en) * | 1995-06-29 | 1998-07-28 | Siemens Microelectronics, Inc. | Localized illumination device |
| GB2317241A (en) * | 1996-09-12 | 1998-03-18 | Schott Fibre Optics | Fibre optic cable passanger seat lighting |
| GB2317241B (en) * | 1996-09-12 | 2000-11-22 | Schott Fibre Optics | Improvements relating to lighting means |
| WO1999010864A1 (en) * | 1997-08-25 | 1999-03-04 | Lewis Gordon C | System for lighting overhead highway signs from a remote light source |
| GB2379497A (en) * | 2001-09-07 | 2003-03-12 | Visteon Global Tech Inc | Optical illuminator with heat dissipation |
| US6609816B2 (en) | 2001-09-07 | 2003-08-26 | Visteon Global Technologies, Inc. | High efficiency illuminator |
| GB2379497B (en) * | 2001-09-07 | 2003-12-31 | Visteon Global Tech Inc | High efficiency Illuminator |
| WO2005106322A1 (en) * | 2004-04-16 | 2005-11-10 | 3M Innovative Properties Company | Luminous elongate device with a light fibre and a light injector |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9122340D0 (en) | 1991-12-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |