WO2007130126A1

WO2007130126A1 - Improved lens and lens arrangement

Info

Publication number: WO2007130126A1
Application number: PCT/US2006/042185
Authority: WO
Inventors: David J. Alessio; David Spartano
Original assignee: Eveready Battery Company, Inc.
Priority date: 2006-04-28
Filing date: 2006-10-26
Publication date: 2007-11-15

Abstract

A light distributor (10) is made of a transparent or translucent material which incorporates a light diffusing or dispersing dopant. The light distributor can be of a tubular construction (12. A) lighting device uses one or more of such distributors which are illuminated by LEDs (14), preferably at both ends.

Description

Improved lens and lens arrangement

Field of the invention

[001] This invention relates to light distributors and lenses, lighting devices using such lense and light distributors, and to methods of manufacturing such lenses, light distributors and lighting devices.

[002] The invention can be applied to light distributors generally, and also to light distributoi which have an appearance similar to that of fluorescent lights.

Background of the invention

[003] Lighting devices rely on lenses and light distributors to transmit light from a light source away for the lighting device. The effectiveness of a lighting device can be dependent upon these lenses and light distributors. This is particularly the case when the light source is of relatively low power output.

[004] Any reference herein to known prior art does not, unless the contrary indicatior appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

Summary of the invention

[005] The present invention provides a light distributor including a transparent or translucent material, with a light dispersant dopant.

[006] The dopant can be a particulate material.

[007] The dopant can be a colourant.

[008] The dopant can be a white colourant.

[009] The dopant can be silica.

[010] The dopant can be within a range of 8% to 30%.

[011] The dopant can be within a range of 10% to 20%.

[012] The dopant can be within a range of 12% to 18%.

[013] The dopant can be of the order of 15%.

[014] The light distributor material can be one of the following: polycarbonate, acrylic, ABS. [015] The distributor can include a textured inside surface.

[016] The distributor can include a textured outside surface.

[017] The textured surface can be produced by a process such a moulding or sand blasting.

[018] The distributor can be is produced by moulding, such as injection moulding, or by extrusion.

[019] The distributor can be produced in segments.

[020] The distributor can be produced in two halves.

[021] The distributor can have a cross section which can be of an elongated shape.

[022] The cross section can have rounded ends.

[023] The rounded ends can be, at least hi part, elliptical.

[024] Between said rounded ends, the sides of said distributor can be one of the following: curved, straight, corrugated.

[025] The shape in cross section can be elliptical or obround.

[026] The cross section can have cuneiform ends.

[027] The distributor can have a cross section which can be lozenge in shape.

[028] The wall thickness of said distributor can be in the range of 4 mm to 10 mm.

[029] The light distributor can have a first surface and the shape of the light distributor can be such that at least some of the direct light from the light source which is reflected on initially striking the first surface is transmitted through the light distributor when the reflected light strikes the first surface after a first or subsequent reflection.

[030] The light distributor can include micro-lenses.

[031] The micro-lenses can be formed by disturbances to the refractive index of the distributor material.

[032] The micro-lenses can be formed by two or more materials having differing refractive indices.

[033] The micro-lenses can be formed by inclusion of particulate material in the light distributor material. [034] The present invention also provides a lighting device including one or more light distributors, each light distributor including one or more respective light sources respectively arranged to illuminate at least a first surface of the respective light distributor.

[035] The respective at least one light source illuminates the light distributor with at least one beam oriented at an angle less than the critical angle.

[036] The respective at least one light source illuminates the light distributor with at least one beam oriented at an angle greater than the critical angle.

[037] The at least one light source illuminates the surface with a beam spanning the critical angle.

[038] The two or more light sources can be used to illuminate the first surface of the light distributor.

[039] There can be at least one light source illuminating the or each light distributor from opposite ends thereof.

[040] There can be two or more light sources at opposite ends of said distributor thereby able to illuminate same.

[041] The first surface can be substantially smooth.

[042] The smooth surface can at least partially reflect direct light from the light source.

[043] The shape of each light distributor can be such that at least some of the direct light from the light source which is reflected on initially striking the first surface is transmitted through the light distributor when the reflected light strikes the first surface after a first or subsequent reflection.

[044] The first surface can be textured.

[045] Each light distributor can have a tubular cross-section.

[046] The light distributor can have an oval section.

[047] The light distributor can have an elliptical section.

[048] The light distributor can have an obround section.

[049] The light distributor can have a section having a pair of parallel sides and a pair of rounded ends. [050] The rounded ends can be convex.

[051] The lighting device can further include at least a first reflector within the light distributor.

[052] The first reflector can be axially coextensive with the light distributor.

[053] The lighting device can further include at least a first end reflector proximate a respective end of the light distributor.

[054] The light device can include a pair of opposed end reflectors.

[055] The at least one light source can be located proximate to at least one end of the light distributor.

[056] The light source can be an LED.

[057] The light source can be preferably of a relatively high intensity (cf: Butterfly

Effect IEEE Spectrum Feb 2006 @ 10; US6831302 Erchak).

[058] A white light can be generated from three LEDs₅ a first having a red light output, a second having a green light output, and a third having a blue light output. Single device white LEDs are commercially available. However, white light can also be generated from a single diode by using a blue indium gallium chip with a phosphor coating.

[059] The light distributor can be made, at least in part, from a material selected from one of the following: ABS, silica, white colourant, polycarbonate.

[060] The at least a portion of said light distributor can include a sand blasted surface.

[061] The lighting device can include 3 light distributors

[062] The light distributors are arranged to provide all- around light

[063] Each light distributor can have at least one light source at either end.

[064] The light sources in each distributor are aligned preferably axially.

[065] The light sources in each distributor are axially offset

[066] The light distributors can be enclosed in a weather-proof housing with a transparent or translucent lens.

[067] A lighting device can include a switch control power to the light sources from a power source. [068] The switch can be a multi-position switch adapted to reduce control the light output.

[069] The switch in a first position can permit power to be provided to all the light sources

[070] The switch in a second position can permit power to be provided to one or more of the light sources and prevent power from being applied to one or more of the light sources.

[071 ] For low power consumption the switch in a third position provides reduced voltage to the light sources, such as for example the batteries are in series, they are switched to parallel or only one half the series can be connected)

[072] A power source can be housed within or enclosed by the light distributor(s).

[073] In cross section the light distributors can be elongated and have a respective longitudinal axis whereby when two or more are present, the respective longitudinal axes are parallel with respect to each other.

[074] In cross section the light distributors can be elongated and have a respective longitudinal axis whereby when two or more light distributors are present the respective longitudinal axes are arranged collinearly.

[075] In cross section the light distributors can be elongated and have a respective longitudinal axis whereby when two or more are present the respective on imaginary radii emanating from a location on said lighting device.

[076] The radii are generally equi-spaced around said location.

[077] The respective longitudinal axes are located collinear or generally parallel to said radii.

[078] The respective longitudinal axes are arranged generally perpendicularly to said radii.

[079] A light housing can enclose said at least one light distributor.

[080] The light housing can be elongated in cross section.

[081] Respective longitudinal axes of a plurality of said light distributors can be arranged generally transverse to a longitudinal axis of said light housing.

[082] Respective longitudinal axes of a plurality of said light distributors can be arranged generally parallel to a longitudinal axis of said light housing. [083] The light distributors can be enclosed in a light housing which can be generally circular.

[084] The invention also provides a method of making a substitute fluorescent tube including the steps of: mixing a particulate material with a mould charge for a light distributor; and moulding a light distributor.

[085] The method can include the steps of: forming a light distributor made of transparent or translucent material with micro-lenses.

[086] The method can include the step of adding a whitening material to the light distributor material.

[087] The invention also provides a method of making a light distributor.

Brief description of the drawings

[088] An embodiment or embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[089] Figure 1 is a perspective view of two light distributors showing the location of

LEDS for use therewith.

[090] Figure 2 is a perspective view of a lighting device utilising the light distributor of Figure 1;

[091] Figure 3 is part cross section through the lighting device of Figure 2; and

[092] Figure 4 is a part cross section through another lighting device similar to that of

Figure 2.

[093] Figure 5 illustrates a cross section through a further light distributor arrangement.

[094] Figure 6 is a conceptual drawing illustrating the principle of the micro-lensing effect.

[095] Figure 7 is a conceptual drawing illustrating the distortion or strain caused by a particle of a first thermal coefficient of expansion in a material of a second coefficient of expansion. Detailed description of the embodiment or embodiments

[096] Illustrated in Figure 1 are two adjacent light distributors 10. Each light distributor 10 is tubular with a cross section which can be described as obround. Light sources 14, for example white LEDs, are provided at either end of the light distributors 10. The wall thickness of the distributor 10 is preferably 5mm, but we believe that a wall thickness in the range of 4 mm to 10 mm will also be effective.

[097] The light distributor 10 is made from a transparent or translucent material which has a light dispersant or diffusing dopant contained therein. The light distributor can be made from acrylic, ABS, or polycarbonate materials.

[098] The dopant is preferably a particulate material, and can include such materials as colourants, most preferably white in colour. Alternatively the dopant can be silica, or silica can be used in conjunction with a colourant.

[099] In the case of silica, this is preferably added to acrylic, and is most preferably added in the proportion of 15% by weight. However, it is expected that silica content within the ranges of 8% to 30%, 10% to 20%, 12% to 18% will result in suitable light distribution properties.

[0100] The light distributor 10 preferably has a smooth inside and outside surface, however it is expected that a light distributor having a textured inside and or outside surface may also be suitable. If texturing is utilised, this can be achieved either by a mould in a moulding process (such as injection moulding) or by a sand blasting process, or by other processes such as mechanical abrasion. The sand blasting process is particularly useful if the distributor 10 is produced by extrusion, but can also be used in the case of the distributor being injection moulded in two halves then assembled for installation into a lighting device. When made in two halves the join lines between the two halves are in a plane that contains the central longitudinal axis, intermediate of and parallel to the straight side portions of the obround cross section.

[0101] While an obround cross section 12 is illustrated in Figure 1, it is expected that other cross sections of circular or elongated shape could produce a useful or similar result to the obround shape. Other cross-sectional shapes, including triangular, square, rectangular, polygonal, etc., can also be used. For example, a lozenge shape might be used or rounded ends which are not purely circular could be used, such as elliptical, curved or convex ends could be appropriates. [0102] With respect to the elongated sides of the distributor these sides are illustrated in

Figure 1 as being straight, but a useful result could be achieved with a curved or even corrugated.

[0103] A light distributor with different optical properties can be produced by utilizing different cross-sectional shapes, such as elliptical.

[0104] Instead of the rounded ends, other profiles, such as cuneiform or chevron shaped ends could be used.

[0105] The internal smooth surface 12 of the light distributor 10 is such that at least some of the direct light from the light sources (in this case two sets of two LEDS 14), which light is reflected on initially striking the smooth surface 12 and is transmitted through the wall of the light distributor 10 when the reflected light strikes the surface 12 after a first or subsequent reflection.

[0106] If required the sets of LED can be reduced to a single LED at one end of the light distributor, hi this instance the length of the distributor can be reduced.

[0107] Preferably the LEDS are oriented, and or have a cone angle such that at least one beam is oriented at an angle less than the critical angle of the material used to make the light distributor 10. Preferably at least one light source or LED will illuminate the surface 12 with a beam which spans the critical angle.

[0108] By illuminating the or each light distributor 10 from opposite ends thereof as is illustrated in Figure 1, even with an LED as a light source, a useable or effective lighting product which produces a pseudo fluorescent effect can be produced.

[0109] If desired, a reflector (not illustrated) can be provided within the confines of the light distributor 10. Such a reflector is preferably axially coextensive with the light distributor 10.

[0110] The light distribution system of Figure 1 has two light sources located proximate to the ends of the light distributor 10.

[0111] Light sources other than LEDS can be used but LEDs are preferred due to their cone angle of emission of light. Further it is believed that better results are achieved by utilising relatively high intensity LEDS such as those produced by the process and system of US6831302 to Erchak and described in IEEE Spectrum Feb 2006 @ 10. [0112] Illustrated in Figure 2 is a lighting device 20, which utilises the light distributor

10 of Figure 1.

[0113] The lighting device includes three tubular light distributors 10 mounted with their axes parallel, a base 28, housing 26 which can contain batteries and control circuitry, a multi-position switch 24, an outer transparent or translucent body 22, a cover 30 and pivoted handle 32.

[0114] The device 20 has three light distributors which provide an all-around lighting system. In this device 20 there are preferably at least one LED light source at either end of each light distributor, in such an arrangement whereby the light sources in each distributor are aligned axially. Where the light distributors have an oblong section, one of the longer faces can be facing radially outward to provide a large radial light transmitting surface.

[0115] The light distributors 10 of Figure 2 are enclosed in a generally cylindrical weather-proof housing 22 which is made as a preferably transparent lens, but alternatively this can be a translucent lens.

[0116] With a plurality of LED light sources being provided, a multi-position switch 24 can be used to control the light output so as to facilitate conservation of the stored energy of the batteries used with the device 20. Thus in a first position, the switch 24 can permit power to be provided to all the light sources, or in a second position it is used to permit power to be provided to one or more of the light sources and prevent power from being applied to one or more of the light sources.

[0117] For low power consumption the switch in the second position can be used to supply reduced voltage to the light sources, such as, for example changing the batteries from, being in series, to being in parallel, or only one half the series can be connected.

[0118] As described in co-pending application PCT/AU2006/000555 the power source, such as alkaline batteries or rechargeables can be housed within or enclosed by the light distributor.

[0119] As will be noticed from Figure 2, the cross sections of the light distributors are elongated. They are illustrated as being obround whereby their longitudinal axes are located generally perpendicular to imaginary radii emanating from a location on said lighting device. These radii are generally equi-spaced around the centre of the lighting device 20, namely with an angular spacing of 120 degrees. [0120] Figure 3 shows a cross section of the lantern of Figure 2, with an optional central tubular reflector 34. Figure 3 more clearly illustrates the orientation of the oblong light distributors 10 with the long faces and the central axes of the light distributors 10 transverse to an imaginary radial from the centre of the lantern.

[0121] Figure 4 illustrates an arrangement similar to that of Figure 3, but with the light distributors 10 rotated so their major axes are radially oriented.

[0122] In Figure 4, these longitudinal axes could be located collinear or generally parallel to the imaginary radii. Such an arrangement may produce a different light radiation pattern from that produced by the arrangement of Figure 2.

[0123] Figure 5 illustrates a further alternative arrangement in which a single light distributor 52 is used. The light distributor 52 is tri-cuspid and included LEDs 14 located at the convex points 54, 56, 58, and at the concave points 60, 62, 64.

[0124] In the system of Figure 1 , the respective longitudinal axes are arranged coUinearly, and this is particularly useful for a lighting device having a lighting housing which is generally rectangular or elongated, as is the case with the lighting devices described in PCT/AU2000/000720. This arrangement of Figure 1, whereby the longitudinal axes are parallel to the width of the light housing as described in this PCT application will provide a useful result. A less effective but a commercially viable alternative is to have the longitudinal axes of the distributors cross section in parallel to each other but being generally perpendicular to the width dimension to the light housings described in PCT/AU2000/000720.

[0125] A possible explanation for the effectiveness of a light distributor using a particulate is micro-lensing effect. The applicant does not assert that this is the main or sole mechanism for the effectiveness of such distributors. A light distributor can be made utilising a micro-lensing effect. Figure 6 illustrates the micro-lensing effect. Micro-lenses can be formed by producing localized variations in the refractive index within the light distributor material. There are a number of ways to achieve this. Particles with differing refractive indices from the bulk distributor material can be provided. The bulk material can be placed under localizes stress by including particles having different thermal expansion coefficients from that of the bulk distributor material so that, for example, during cooling from a moulding process the bulk material will have localized stress in the vicinity of the particles. The stress can be influenced by the rate of cooling. [0126] Micro-lensing produces an image of the light source, whereas plain scattering or reflection only produces the unfocussed rays. The micro-lensing effect produces a multiplicity of apparent light sources within the doped ABS, imitating the phosphors of a fluorescent light. Of course, the lenses may not be perfect optical focussing lenses, but may produce a sufficient focussing of the light to give the overall appearance similar to that of a fluorescent light.

[0127] This drawing does not include the scattering, reflection, and deflection effects which tend to homogenize the appearance.

[0128] One method of producing a pseudo-fluorescent appearance is to incorporate micro-lenses in the light distributor as shown in Figure 6. Figure 6 is a conceptual drawing illustrating the principle of the micro-lensing effect using a single "layer" of micro-lenses 604. In practice, the light distributor could be one or more orders of magnitude thicker than a single layer of particles.

[0129] Figure 6 shows a light distributor 602 including a plurality of micro-lenses 604,

(not to scale). The micro-lenses produce images 608, 610 of the light source 606 at the focal point of the micro-lens.

[0130] The inclusion of a particulate dopant in the base material of the light distributor can produce a micro-lens effect around the particulate dopant resulting, for example, from either the difference in refractive index between the dopant and the base material, or from thermal contraction stresses between the dopant and the base material or from both of these effects. Thus the particulate dopant can be chosen for its size, shape, refractive index, thermal coefficient of expansion and other features which influence the micro-lensing effect.

[0131] Figure 7 is a conceptual illustration of the strain induced in the light distributor material 702 by a particle 704 having a different thermal coefficient of expansion. The strain is indicated conceptually by the curved lines 706 in proximity to the particle 704. The degree of strain can be influenced by the moulding process temperature and the cooling rate.

[0132] The particulate dopant can be chosen to have substantially uniform micro- lensing characteristics. Alternatively, the dopant can be chosen to have non-homogeneous micro-lensing characteristics. Two or more different doping materials can be used.

[0133] The focal point of the individual micro-lenses can be influenced by local effects such as different cooling rates between the outer surfaces compared with the bulk material within the light distributor, differences in particle size and shape or other effects. Thus the focal points of the individual micro-lenses can vary. [0134] In addition, where the light passes through a plurality of such micro-lenses, the focal point will depend on the number of micro-lenses in the light path. Thus the light produced by the light distributor will have a plurality of focal points covering a range of distances.

[0135] Referring to Figure 6, a light source 606 produces light which impinges on the

"input' surface of the distributor 602. This light then is focussed by the micro-lenses 604 and projects images of the light source 606 through the output surface of the light distributor 602.

[0136] In a further embodiment, the light can be reflected back through the light distributor by a reflective surface. In one embodiment, the reflective surface can be the surface of the distributor opposite to the input surface, so that the light is reflected back through the input surface and distributed on the input side of the distributor. Where the distributor is tubular, and the light source is internal, part of the tubular surface can be reflective to reflect light through the remainder of the tubular surface.

[0137] A simulated fluorescent tube has a number of advantages over a standard fluorescent tube. A standard fluorescent tube requires an internal coating of phosphorescent material and must be sealed to contain mercury gas. It also needs a discharge initiation circuit. A simulated fluorescent tube embodying the invention does not need to be sealed, the inside of the tube does not need to be coated with phosphors, it can operate at low voltages used to operate LEDs, and it does not contain poisonous or harmful gas. Thus a simulated fluorescent tube embodying the invention can be assembled without the need for clean-room facilities of a standard required for fluorescent tubes. The light diffuser of the present invention is a passive device, whereas a fluorescent tube is an active discharge tube. In addition, when used with LEDs as the light source, a lighting device will have a low power consumption compared with an incandescent light.

[0138] As mentioned, micro-lensing is only one possible mechanism by which the effect may be achieved. Other potential mechanisms such as scattering and reflection may contribute to the result.

[0139] We have found that a dopant concentration of the order of 15 % whitening in

ABS produced satisfactory results, because it provided: an appropriate percentage of light transmission (relative to the amount of light "kept" within the tube), and an appropriate distribution of light along the axial length of the tube. We have found that some other concentrations left a "hole" in the middle of the light tube. [0140] We have used two types of material: Acrylic/silica and ABS with a colorant.

[0141] In an experiment, we used an ABS tube with white colourant tube illuminated by diodes at either end of the tube. Each tube was 108mm in length. We chose to measure the innner 74%, or 80mm of the tube. We took five readings from 3 feet (~ 0.9m) in units of footlamberts. The readings were taken at roughly 0, 20, 40, 60, and 80mm. The readings were 315, 201, 180, 202, and 315 footlamberts respectively. For measuring purposes, we segmented the external area of the tube into three areas: a central area and two areas axially disposed and adjacent the LEDs. We found that visually the light appears uniform within this central area, and when measured varies less than 42%.

[0142] The "42%" is calculated by dividing the tube into six areas. Areas 1 and 6 are the "end" areas proximate the LEDs, and the central area is equally divided into areas 2-5. The average foot lamberts for this central area is 223.5, which is calculated by taking the average of each area (each calculated by linear regression). The 315 foot lamberts measurements at each end represent the 42% deviation from this calculated mean. This maximum deviation can be our definition for "uniform light distribution".

[0143] The acrylic/silica tube has not been evaluated to the same extent, but was more uniform.

[0144] Where ever it is used, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of. A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear.

[0145] It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. All of these different combinations constitute various alternative aspects of the invention.

[0146] While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, and all modifications which would be obvious to those skilled in the art are therefore intended to be embraced therein.

Claims

1. A light distributor including a transparent or translucent material, with a light dispersant or diffusing dopant.

2. A light distributor as claimed in claim 1 , wherein the dopant is a particulate material.

3. A light distributor as claimed in claim 1 or 2, wherein the dopant is a colourant.

4. A light distributor as claimed in any one of the preceding claims wherein the dopant is a white colourant.

5. A light distributor as claimed in any one of claims 1 to 3, wherein the dopant is silica.

6. A light distributor as claimed in any one of the preceding claims, wherein the dopant is within a range of 8% to 30%.

7. A light distributor as claimed in claim 6, wherein the dopant is within a range of 10% to 20%.

8. A light distributor as claimed in any one of claims 7 or 8, wherein the dopant is within a range of 12% to 18%.

9. A light distributor as claimed in any one of claims 6 to 8, wherein the dopant is of the order of 15%.

10. A light distributor as claimed in any one of the preceding claims wherein said material is one of the following: polycarbonate, acrylic, ABS.

11. A light distributor as claimed in any one of the preceding claims, wherein said distributor includes a textured inside surface.

12. A light distributor as claimed in any one f the preceding claims wherein said distributor includes a textured outside surface.

13. A light distributor as claimed in claim 11 or 12, wherein said textured surface is produced by a process such a moulding or sand blasting.

14. A light distributor as claimed in any one of the preceding claims wherein said distributor is produced by moulding, such as injection moulding, or by extrusion.

15. A light distributor as claimed in claim 14 wherein said distributor is produced in two halves.

16. A light distributor as claimed in any one of the preceding claims wherein said distributor has a cross section which is of an elongated shape.

17. A light distributor as claimed in claim 16, wherein said cross section has rounded ends.

18. A light distributor as claimed in claim 16 wherein said rounded ends are at least in part, elliptical.

19. A light distributor as claimed in claim 17 or 18, wherein between said rounded ends, the sides of said distributor are one of the following: curved, straight, corrugated.

20. A light distributor as claimed in any one of claims 16 to 19, wherein said shape in cross section is elliptical or obround.

21. A light distributor as claimed in claim 17, wherein said cross section has cuneiform ends.

22. A light distributor as claimed in any one of claims 1 to 15 wherein said distributor has a cross section which is lozenge in shape.

23. A light distributor as claimed in any one of the preceding claims wherein the wall thickness of said distributor is in the range or 4 mm to 10 mm.

24. A light distributor as claimed in any one of the preceding claims wherein the light distributor has a first surface and the shape of the light distributor is such that at least some of the direct light from the light source which is reflected on initially striking the first surface is transmitted through the light distributor when the reflected light strikes the first surface after a first or subsequent reflection.

25. A light distributor including micro-lenses.

26. A light distributor as claimed in claim 25, wherein the micro-lenses are formed by disturbances to the refractive index of the distributor material.

27. A light distributor as claimed in claim 25 or claim 26, wherein the micro-lenses are formed by two or more materials having differing refractive indices.

28. A light distributor as claimed in any one of claims 25 to 27, wherein the micro-lenses are formed by inclusion of particulate material in the light distributor material.

29. A light distributor as claimed in claim 28, wherein the micro-lenses are formed by the inclusion of substantially spherical particles.

30. A light distributor in the form of a fluorescent tube substitute including a light distributor as claimed in any one of the preceding claims.

31. A lighting device including one or more light distributors as claimed in any one of claims 1 to 30, each light distributor including one or more respective light sources respectively arranged to illuminate at least a first surface of the respective light distributor.

32. A lighting device as claimed in claims 31, wherein said respective at least one light source illuminates the light distributor with at least one beam oriented at an angle less than the critical angle.

33. A lighting device as claimed in claim 31 or 32, wherein said respective at least one light source illuminates the light distributor with at least one beam oriented at an angle greater than the critical angle.

34 A lighting device as claimed in any one of claims 31 to 33, wherein said at least one light source illuminates the surface with a beam spanning the critical angle.

35. A lighting device as claimed in any one of claims 31 to 34, wherein two or more light sources are used to illuminate the first surface of the light distributor.

36. A lighting device as claimed in any one of claims 31 to 35, wherein there is at least one light source illuminating the or each light distributor from opposite ends thereof.

37. A lighting device as claimed in claim 36 wherein there are two or more light sources at opposite ends of said distributor thereby able to illuminate same.

38. A lighting device as claimed in any one of claims 31 to 37, wherein said first surface is substantially smooth.

39. A lighting device as claimed in claim 30, wherein said smooth surface at least partially reflects direct light from the light source.

40. A lighting device as claimed in any one of claims 31 to 39, wherein the shape of each light distributor is such that at least some of the direct light from the light source which is reflected on initially striking the first surface is transmitted through the light distributor when the reflected light strikes the first surface after a first or subsequent reflection.

41. A lighting device as claimed in any one of claims 31 to 37 wherein said first surface is textured.

42. A lighting device as claimed in any one of claims 31 to 41 wherein each light distributor has a tubular cross-section.

43. A lighting device as claimed in any one of claims 31 to 42 wherein said light distributor has an oval section.

44. A lighting device as claimed hi any one of claims 31 to 42 wherein said light distributor has an elliptical section.

45. A lighting device as claimed in any one of claims 31 to 42 wherein said light distributor has an obround section.

46. A lighting device as claimed in any one of claims 31 to 42 wherein said light distributor has a section having a pair of parallel sides and a pair of rounded ends.

47. A lighting device as claimed hi claim 46 wherein said the rounded ends are convex.

48. A lighting device as claimed in any one of claims 31 to 47 including at least a first reflector within the light distributor.

49. A lighting device as claimed in claim 48, wherein said first reflector is axially coextensive with the light distributor.

50. A lighting device as claimed in any one of claims 31 to 49, including at least a first end reflector proximate a respective end of the light distributor.

51. A lighting device as claimed in claim 50, wherein said the light device includes a pair of opposed end reflectors.

52. A lighting device as claimed in any one of claims 31 to 51 , wherein said at least one light source is located proximate to at least one end of the light distributor.

53. A lighting device as claimed hi anyone of claims 31 to 52 wherein said light source is an LED.

54. A lighting device as claimed in any one of claims 31 to 53 wherein said light source is of a relatively high intensity.

55. A lighting device as claimed in any one of claims 31 to 54 wherein said light distributor is made, at least in part, from a material selected from one of the following: ABS, silica, white colourant, polycarbonate.

56. A lighting device as claimed in any one of claims 31 to 55 wherein at least a portion of said light distributor includes a sand blasted surface.

57. A lighting device as claimed in any one of claims 31 to 56 wherein the lighting device includes 3 light distributors

58. A lighting device as claimed in any one of claims 31 to 57 wherein the light distributors are arranged to provide all- around light

59. A lighting device as claimed in claim 58 wherein each light distributor has at least one light source at either end.

60. A lighting device as claimed in any one of claims 58 or 59 wherein the light sources in each distributor are aligned preferably axially.

61. A lighting device as claimed in any one of claims 58 or 59 wherein the light sources in each distributor are axially offset

62. A lighting device as claimed in any one of claims 31 to 61 wherein the light distributors are enclosed in a weather-proof housing with a transparent or translucent lens.

63. A lighting device as claimed in any one of claims 31 to 62 wherein a switch is provided to provide power to the light sources from a power source.

64. A lighting device as claimed in claim 63 wherein the switch is a multi-position switch adapted to reduce control the light output.

65. A lighting device as claimed in any one of claims 63 or 64 wherein the switch in a first position permits power to be provided to all the light sources

66. A lighting device as claimed in claim 65, wherein the switch in a second position permits power to be provided to one or more of the light sources and prevents power from being applied to one or more of the light sources.

67. A lighting device as claimed in claim 65, wherein for low power consumption the switch in a third position provides reduced voltage to the light sources.

68. A lighting device as claimed in any one of claims 31 to 67 wherein a power source is housed within or enclosed by the light distributor(s).

69. A lighting device as claimed in any one of claims 31 to 68 wherein, in cross section, the light distributors are elongated and have a respective longitudinal axis whereby when two or more are present, the respective longitudinal axes are parallel with respect to each other.

70. A lighting device as claimed in any one of claims 31 to 68, wherein in cross section the light distributors are elongated and have a respective longitudinal axis whereby when two or more are present the respective longitudinal axes are arranged collinearly.

71. A lighting device as claimed in any one of claims 31 to 68, wherein in cross section the light distributors are elongated and have a respective longitudinal axis whereby when two or more are present the respective on imaginary radii emanating from a location on said lighting device.

72. A lighting device as claimed in claim 71 wherein said radii are generally equi-spaced around said location.

73. A lighting device as claimed in claim 71 or 72 wherein said respective longitudinal axes are located collinear or generally parallel to said radii.

74. A lighting device as claimed in claim 71 or 72 wherein said respective longitudinal axes are arranged generally perpendicularly to said radii.

75. A lighting device as claimed in any one of claims 31 to 74, wherein a light housing encloses said at least one light distributors.

76. A lighting device as claimed in claim 75, wherein said light housing is elongated in cross section.

77. A lighting device as claimed in claim 76, wherein respective longitudinal axes of a plurality of said light distributors are arranged generally transverse to a longitudinal axis of said light housing.

78. A lighting device as claimed in claim 76, wherein respective longitudinal axes of a plurality of said light distributors are arranged generally parallel to a longitudinal axis of said light housing.

79. A lighting device as claimed in any one of claims 71 to 74, wherein said light distributors are enclosed in a light housing which is generally circular.

80. A method of making a substitute fluorescent tube including the steps of: mixing a particulate material with a mould charge for a light distributor; and moulding a light distributor.

81. A method of making a substitute fluorescent tube including the steps of: forming a light distributor made of transparent or translucent material with micro-lenses.

82. A method as claimed in claim 80 or 81 including the step of adding a whitening material to the light distributor material.

83. A lighting distributor being substantially as herein described with reference to respective embodiments as illustrated in accompanying drawings.

84. A lighting device being substantially as herein described with reference to respective embodiments as illustrated in accompanying drawings.

85. A method of making a light distributor substantially as herein described with reference to the accompanying drawings.