GB2432653A

GB2432653A - Torch with LED array combined into single beam

Info

Publication number: GB2432653A
Application number: GB0523877A
Authority: GB
Inventors: David Fowler; Stephen Edwin Dalby
Original assignee: GAIASPHERE Ltd
Current assignee: GAIASPHERE Ltd
Priority date: 2005-11-24
Filing date: 2005-11-24
Publication date: 2007-05-30
Also published as: GB0523877D0

Abstract

An electric torch or other illumination device includes an array of light sources, such as LEDs 10. The lights each emit a beam 12 towards an axis 14. The light beam is redirected by a reflector or refractor 16 into an axial direction 18. The light beams of the array are combined into a single axial beam 22. The spread of the beam can be manipulated in a number of ways. The configuration allows a number of LEDs to be combined to produce a brighter output.

Description

I

Illumination Device This invention concerns' electrical illumination devices, particularly but not necessarily exclusively electric torches, sometimes known as flashlights.

For many years, torches have conventionally used small incandescent light bulbs, but recently light emitting diodes (LED5) have become available as an alternative. A problem with this is that the output of an LED is limited so that an intense beam is necessarily narrow, and in a torch the compromise between intensity (or brightness) and beam-width often results in illumination that is either not broad enough or not bright enough.

LEDs can be made very small, which allows a plurality of LEDs to be arranged side-by-side in a torch to emit separate beams which together provide a spread of illumination. However the separate beams individually have the same restrictions as a single beam.

It is an object of the present invention to enable beams from a plurality of LED5 or other light sources to be combined into a single beam.

Thus according to the invention there is provided an electrical illumination device comprising a plurality of light sources arranged about an axis each operative in use to produce an individual beam of light and a first optical element arranged to collect the individual beams and collimate them into a combined axial beam, characterised in that in use each individual beam is emitted from its respective light source generally transversely relative to the axis and then redirected by a second optical element into an axial direction.

Those skilled in the science will appreciate that the invention allows the individual beams to be redirected as close to the axis as may be required for intense illumination or alternatively dispersed around the axis for a broader beam. In short, the combined beam can be manipulated according to n requirements. Further, the arrangement of the light sources -which are preferably LEDs -permits the outputs from a substantial number of light sources to be combined.

Preferably the individual beams are emitted from the respective light sources radially inwards towards the axis, and the light sources may be symmetrically arranged about the axis.

The first optical element may comprise a lens.

The second optical element may redirect the individual beams by reflection or refraction.

The second optical element may redirect the individual beams on to parts of the first optical element optically formed to create substantially even illumination across the combined beam.

Each second optical element may comprise an optical prism, or an optical pipe, and the second optical elements may be integrated with the first optical element.

To manipulate the combined beam as to spread and/or focus (a) the first and second optical elements may be mutually separated by a distance which is adjustable to vary the spread and/or focus of the combined beam, or (b) the light sources and the second optical elements may be mutually separated by a distance which is adjustable to vary the spread and/or focus of the combined beam or (c) each second optical element may be arranged at an adjustable angle to the respective individual beam.

The electrical illumination device may have a sealed casing. So arranged, the torch preferably includes an electrically rechargeable battery, inductive coupling means whereby the battery is recharged, and an external slider or the like magnetically coupled to a switch whereby the LEDs may be turned on and off alternatively. n

Other features of the invention will be apparent from the following description, which is made by way of example only with reference to the accompanying schematic drawings in which -Figure 1 is a plan view illustrating a basic illumination device according to the invention; Figure 2 is a front elevation illustrating an illumination device according to the invention in which a combined beam is formed from the outputs of five light sources; Figure 3 is a plan view corresponding to Figure 2; Figure 4 is an isometric view corresponding to Figure 2; Figure 5 is a plan view illustrating a modification of the illumination device of Figure 1; Figure 6 is an isometric view corresponding to Figure 2; Figure 7 is a front elevation of another illumination device according to the invention in which a combined beam is formed from the outputs of five light sources; Figure 8 is a plan view corresponding to Figure 4; Figure 9 is an isometric view corresponding to Figure 4; Figure 10 is an isometric view corresponding to Figure 4 and illustrating how the spread of the combined beam may be adjusted; Figure 11 is a plan view illustrating a prism for redirecting the light beam from an individual light source; Figure 12 is an isometric view corresponding to Figure 8; Figure 13 is a front elevation of an array of prisms for redirecting light beams from five light sources; Figure 14 is a plan view corresponding to Figure 10; Figure 15 is an isometric view corresponding to Figure 10; n Figure 16 is a plan view illustrating a light pipe for redirecting the light beam from an individual light source; Figure 17 is an isometric view corresponding to Figure 16; Figure 18 is a front elevation of an array of light pipes for redirecting light beams from five light sources; Figure 19 is a plan view corresponding to Figure 18; Figure 20 is an isometric view corresponding to Figure 18; Figure 21 is a general plan view from above of a torch embodying the invention; Figure 22 is an end elevation corresponding to Figure 21; Figure 23 is a side elevation corresponding to Figure 21; Figure 24 is a plan view of the torch of Figures 21 to 23 viewed from underneath; Figure 25 is a plan view from above showing the torch of Figures 21 to 24 engaged with a charging base; and Figure 26 is an isometric view corresponding to Figure 25.

Referring first to Figure 1, this shows a light source 10 such as an LED.

The LED 10 is operative to emit a light beam 12 towards an axis 14. The light beam 12 is incident upon an optical element 16 in the form of a reflector (which may be replaced by a refracting element) that redirects the light beam 12 into an axial direction as indicated at 18. The redirected light beam 18 is collected by an optical element 20 in the form of a lens, which collimates it to lie parallel with the axis 14, as indicated at 22 The collimated beam 22 has a spread a at distance b from the lens 20 which is dependent upon - (a) The distance c between the optical element 16 and the optical n element 20; (b) The distance d between the light source 10 and the optical element 16; and (c) The angle of incidence 6 of the light beam 12 upon the optical element 16.

It follows that the beam 22 may be manipulated as to spread and focus (and implicitly its intensity) by adjusting any or all of c, d and 6.

By providing a plurality of devices like those illustrated in Figure 1, the outputs of a plurality of light sources may be combined in a single beam, as will now be described with reference to Figures 2 to 4.

As shown in Figures 2 to 4, five light sources 30 are arranged about an axis 32. The light sources 30 emit individual beams 34 of light transversely across the axis 32 to five respective optical elements 36, which redirect the beams 34 (by reflection or refraction) into an axial direction as indicated at 38.

The redirected beams 38 are collected by a lens 40 that collimates them into a combined beam as indicated at 42.

It will be understood from the foregoing description with reference to Figure 1 that the combined beam 42 may readily be manipulated as to spread and focus. It will also be understood that -especially with small light sources such as LEDs -a (possibly large) plurality of light sources may be provided.

It follows that the arrangement of Figures 2 to 4 allows the outputs from a plurality of light sources to be combined in a single beam that can be as intense or as spread as may be required.

It will be noted (most cTearly from Figure 2) that the individual beams 34 cross the axis 32. That is, each reflector/refractor 36 is arranged on the opposite side of the axis 32 from its respective light source 30. The reflector/refractors 36 are close packed about the axis 34, to facilitate collimation of the beams 38 into the combined beam 42. The light sources 30 are relatively widespread This allows a substantial number of light sources 30 to be provided. Figure 2 also shows that an odd number of light sources 30 (and correspondingly of reflector/refractors 36) arranged in circumferential symmetry about the axis 32 means that the beam 34 from each light source 30 easily passes between the reflector/refractor-s on the same side of the axis 32, and is thereby not blocked.

The arrangement of Figures 2 to 4 has a simple lens 40 collecting all the beams 38. However the collecting element may alternatively be formed to focus the beams individually. Such an arrangement is illustrated by Figures 5 and 6, in which a light source 50 emits a transverse light beam 52 that is redirected axially by a reflecting or refracting optical element 54. The individual redirected beam 56 is then collected by a lens 58 formed to collimate that individual beam as indicated at 60.

The spread of the beam 60 may be varied, for instance by adjusting the distance e between the optical elements 54 and 58.

With a plurality of devices like those illustrated in Figures 5 and 6, the outputs of a plurality of light sources may be combined in a single beam, as will now be described with reference to Figures 7 to 10, which shows five light sources 70 arranged about an axis 72. The light sources 70 emit individual beams 74 of light transversely across the axis 72 to five respective optical elements 76, which redirect the beams 74 (by reflection or refraction) into an axial direction as indicated at 78. The redirected beams 78 are collected by a lens 80 comprising five sections each formed to collimate an individual beam and combine it with the others into a single beam 82 combining the outputs of n all the light sources 70.

Because the spread of each individual beam may be varied as described above with reference to Figures 5 and 6, it follows that the spread of the combined beam may also be varied, eg by increasing it from a width f (Figure 9) to a width g (Figure 10).

The reflecting/refracting optical elements and lenses aforedescribed may be replaced by an integrated optical element as iHustrated by Figures 11 and 12, comprising a prism 90 for axially redirecting a transverse beam 92 and a lens 94 for collimating the redirected beam 96 as indicated at 98.

As shown in Figures 11 and 12, the lens 94 is integral with the prism 90, for simplicity and cheapness; but it is to be understood that the lens 94 may be separate, and movable to manipulate the beam 98.

A plurality of integrated prisms and lenses may be provided as a unitary structure 100 as illustrated by Figures l3to 15.

The prism and lens arrangement of Figures 11 and 12 may be replaced by an optical pipe 110 as illustrated by Figures 16 and 17. A plurality of such optical pipes may be combined together in a unitary assembly 120 as illustrated by Figures 18 to 20.

A difference between the arrangements of Figures 16 to 20 and the other arrangements may now be noticed. Where an optical pipe assembly 120 is used to redirect the transverse beams, these do not have to cross the central axis. Two corollaries of this are (a) that the light sources do not need to be symmetrically arranged around the axis in order to work efficiently and (b) the emission point of each light source is not restricted to any particular form.

Further particularly advantageous features of a torch embodying the invention will now be discussed with reference to Figures 21 to 24.

First, the torch 110 illustrated in Figures 21 to 24 has a sealed casing 112. This means that the torch 110 is not adversely affected by moisture, and in fact it is completely waterproof. Use of the torch is therefore not affected by bad weather, the presence of water, etc. Next, for robustness, the casing 112 is formed of aircraft-grade aluminium alloy.

To give long life to the torch 110 with its sealed casing 112, the torch is powered by a rechargeable battery (not shown in the drawing) located within the casing 112. Such a battery may have a range of known configurations, but in the present case it comprises three AAA cells of the NiMH type, delivering a total of 3.6V.

To operate the torch 110, it is necessary to provide some mechanism external of the casing 112 whereby power may be delivered from the battery within the casing. This is done by means of a user-operated slider 114 magnetically coupled to the battery circuit.

The battery pack is recharged by way of an inductive coupling arrangement, and for this purpose the casing 112 is formed with an electrically non-conductive window 116 in the underside of the torch 110. Referring now to Figures 25 and 26, a charging base 118 is configured and arranged to receive the torch 110 with its window 116 face down upon a charging zone 120. Then a primary induction coil in the charging base 118 is adjacent a secondary induction coil in the torch 110, so that when the charging base 118 is energised charging power will be transferred to the torch 110 by inductive coupling. (It is considered that those skilled in the science should be readily able to devise suitable inductive coupling arrangements, and that it is therefore not necessary to provide a detailed description or illustration herein. However it n may be noted that the system of Figures 25 and 26 utilises a coil winding 17.5mm x 12.0mm x 5.0mm on a ferrite core 7.5mm x 7.0mm x 21.0mm, with an air gap of approximately 2.4mm.) No switching or other operation is required to start charging -rather, as long as the charging base 118 is energised, charging starts as soon as the torch 110 is properly engaged therewith. To confirm that charging is in progress, the charging circuit includes an indicator lamp 122 (such as a small LED) visible through the casing 112.

The invention is advantageous in torches, which are inherently compact and portable. However it is to be understood that it may also be used in other illumination devices such as vehicle lights and helmet lights, or in non-portable devices.

LEDs are particularly appropriate light sources for the invention, but other light sources may be used, and other modifications and adaptations of the arrangments described will be apparent to those skilled in the science.

Claims

Claims 1. An electrical illumination device comprising a plurality of

light sources arranged about an axis each operative in use to produce an individual beam of light and a first optical element arranged to collect the individual beams and collimate them into a combined axial beam, characterised in that in use each individual beam is emitted from its respective light source generally transversely relative to the axis and then redirected by a second optical element into an axial direction.

2. An electrical illumination device as claimed in claim I characterised in that the individual beams are emitted from the respective light sources radially inwards towards the axis.

3. An electrical illumination device as claimed in claim I or claim 2 characterised in that the light sources are symmetrically arranged about the axis.

4. An electrical illumination device as claimed in any preceding claim characterised in that each light source comprises an LED.

5. An electrical illumination device as claimed in any preceding claim characterised in that the first optical element comprises a lens.

6. An electrical illumination device as claimed in claim 5 characterised in that the second optical element redirects the individual beams by reflection or refraction. fl

7. An electrical illumination device as claimed in claim 5 or claim 6 characterised in that the second optical element redirects the individual beams on to parts of the first optical element optically formed to create substantially even illumination across the combined beam.

8. An electrical illumination device as claimed in any preceding claim characterised in that each second optical element comprises an optical prism.

9. An electrical illumination device as claimed in any preceding claim characterised in that the individual beams emitted by the Eight sources extend across the axis 10. An electrical illumination device as claimed in any preceding claim characterised in that the light sources are arranged in circumferential symmetry about said axis.

11. An electrical illumination device as claimed in any preceding claim characterised in that the number of light sources is odd.

12. An electrical illumination device as claimed in any of claims Ito 8 characterised in that each second element comprises an optical pipe.

13. An electrical illumination device as claimed in claim 12 wherein the individual beams emitted by the light sources do not extend across the axis. n

14. An electrical illumination device as claimed in any preceding claim characterised in that the second optical elements are integrated with the first optical element.

15. An electrical illumination device as claimed in any preceding claim characterised in that the first and second optical elements are mutually separated by a distance which is adjustable to vary the spread and/or focus of the combined beam.

16. An electrical illumination device as claimed in any preceding claim characterised in that the light sources and the second optical elements are mutually separated by a distance which is adjustable to vary the spread and/or focus of the combined beam.

17. An electrical illumination device as claimed in any preceding claim in which each second optical element is arranged at an angle to the respective individual beam, characterised in that each said angle is adjustable to vary the spread and/or focus of the combined beam.

18. An electrical illumination device as claimed in any preceding claim characterised in that said device has a casing.

19. An electrical illumination device as claimed in claim 18 characterised in that said casing is sealed.

20. An electrical illumination device as claimed in claim 19 or claim 20 characterised in that the device is powered by an electrically rechargeable n battery within said casing.

21. An electrical illumination device as claimed in claim 20 characterised in that the device includes inductive coupling means whereby the battery is recharged.

22. An electrical illumination device as claimed in any of claims 18 to 21 characterised in that said inductive coupling means comprises an electromagnetic interference filter module, an induction charger module and a battery charging module.

23. An electrical illumination device as claimed in claim 22 characterised in that the electromagnetic interference filter module is included within a charging base for the device, the battery charging module is included within the device, and the induction charger module is divided between the charging base and the device, with a primary coil in the charging base and a secondary coil in the device.

24. An electrical illumination device as claimed in claim 23 characterised in that charging base is configured and arranged to receive the device with the primary and secondary coils mutually adjacent, whereby the battery is recharged automatically whenever the charging base receives the device.

25. An electrical illumination device as claimed claim 24 characterised in that the device includes an indicator lamp illuminated during charging.

26. An electrical illumination device as claimed in any of claims 18 to characterised in that said casing is of metal.

27. An electrical illumination device as claimed in claim 26 characterised in that said metal comprises aluminium or aluminium alloy.

28. An electrical illumination device as claimed in claim 26 or claim 27 characterised in that said casing includes an electrically non-conductive window for the inductive coupling.

29. An electrical illumination device as claimed in any of claims 18 to characterised in that said casing is electrically non-conductive.

30. An electrical illumination device as claimed in any of claims 18 to 29 including a switch for turning the light sources on and off alternatively, characterised in that the switch is operated from outside the casing by means of a slider or the like magnetically coupled to the switch.

31. An electrical illumination device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.