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Title:
IMPROVEMENTS IN OR RELATING TO INFRARED AND/OR ULTRAVIOLET LIGHTS
Document Type and Number:
WIPO Patent Application WO/2017/194932
Kind Code:
A1
Abstract:
Disclosed is a lighting unit comprising a substrate with a reflective surface, the substrate being formed of, or comprising at least one channel section (4), said channel section (4) comprising a major light source (7) and a minor light source (9), said light sources being disposed in a corresponding respective major (6) and minor groove (8) formed in the channel section (4), the major (6) and minor (8) light sources within the same channel section (4) being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel, the light sources being selected from the group consisting of : an ultraviolet light source; and an infrared light source.

Inventors:
LEAK, Peter (Hyde House The Hyde,Edgware Road, London Greater London NW9 6LA, NW9 6LA, GB)
Application Number:
GB2017/051291
Publication Date:
November 16, 2017
Filing Date:
May 10, 2017
Export Citation:
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Assignee:
LUXTEC LIMITED (Hyde House, The HydeEdgware Road, London NW9 6LA, NW9 6LA, GB)
International Classes:
A61L9/20; B05D3/06; B41F23/04; F24C7/04; F26B3/28
Domestic Patent References:
WO2007147100A22007-12-21
Foreign References:
GB1581533A1980-12-17
GB1565654A1980-04-23
CH690031A52000-03-31
Attorney, Agent or Firm:
LIPSCOMBE, Martin et al. (Nash Matthews LLP, 24 Hills Road, Cambridge Cambridgeshire CB2 1JP, CB2 1JP, GB)
Download PDF:
Claims:
Claims

1. A lighting unit comprising a substrate with a reflective surface, the substrate being formed of, or comprising at least one channel section, said channel section comprising a major light source and a minor light source, said light sources being disposed in a corresponding respective major and minor groove formed in the channel section, the major and minor light sources within the same channel section being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel, characterized in that the light sources are selected from the group consisting of: an ultraviolet light source; and an infrared light source.

2. A lighting unit according to claim 1, wherein the light sources are tubular.

3. A lighting unit according to claim 1 or 2, wherein the lighting unit comprises a single channel section.

4. A lighting unit according to claim 1 or 2, wherein the lighting unit comprises a plurality of channel sections.

5. A lighting unit according to claim 4, wherein the channel sections form a parallel array with little or no gap between adjacent channel sections.

6. A lighting unit according to claim 4 or 5, wherein each channel section has a pair of side walls, which side walls are common to or shared with the adjacent channel sections on each side.

7. A lighting unit according to claim 6, wherein the side walls are substantially vertical when the substrate is laid horizontally.

8. A lighting unit according to any one of the preceding claims, wherein the reflective surface of the substrate comprises specular aluminium or gold.

9. A lighting unit according to claim 8, wherein the reflective surface comprises bright-dipped, anodised aluminium alloy.

12. A lighting unit according to any one of the preceding claims, wherein the light sources comprise a tube which bends through 180° at the end of a channel section, such that a single tube forms a serpentine path through a plurality of linear channel sections.

13. A lighting unit according to claim 2, wherein the ratio of the diameter of the major light source tube to the diameter of the minor light source tube is in the range 1.3 : 1 to 1.7: 1, preferably 1.4: 1 to 1.6: 1.

14. A lighting unit according to any one of the preceding claims, wherein the minor groove is formed above and to one side of the major groove.

15. A lighting unit according to claim 4, wherein each of the plurality of channel sections is essentially identical in profile.

16. A lighting unit according to any one of the preceding claims, wherein the or each channel section has a target plane aperture width in the range 20-40mm, more preferably 20-35mm.

17. A lighting unit according to any one of claims 1-15, wherein the or each channel section has a target plane aperture width in the range 70-80mm.

18. A method of making a lighting unit in accordance with any one of the preceding claims, the method comprising the step of: assembling, in operable relationship: a substrate with a reflective surface, the substrate being formed of, or comprising, at least one channel section; and a major light source and a minor light source, said light sources being disposed in a corresponding respective major and minor groove formed in the channel section, the major and minor light sources within the same channel section being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel, characterized in that the light sources are selected from the group consisting of: an ultraviolet light source; and an infrared light source.

Description:
Title: Improvements in or Relating to Infrared and/or Ultraviolet Lights Field of the Invention

The present invention relates to infrared and ultraviolet lighting units, and to uses thereof.

Background of the Invention

The present invention aims to provide an infrared or ultraviolet lighting unit, having greater light output than previous devices, whilst still having a lower electrical power consumption than more conventional lighting units.

Co-pending PCT application number PCT/GB2016/050338 (unpublished at the date of filing of the present application; a copy is attached hereto for reference) discloses a lighting panel (especially a lighting panel adapted and configured for use in a backlight unit for a display panel), the lighting panel comprising a substrate with a reflective surface, the substrate being formed of, or comprising, a plurality of channel sections, each channel section comprising a major light source and a minor light source, the light sources being disposed in a corresponding respective major and minor groove formed in the channel sections, the major and minor groove formed in the channel sections, the major and minor light sources within the same channel section being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel.

The light sources disclosed in PCT/GB2016/050338 are preferably electroluminescent light tubes. The present invention is based, inter alia, on the realization that the lighting panel disclosed in PCT/GB2016/050338 can be adapted for uses other than as a backlight for a display panel, and that light sources other than electroluminescent tubes may be employed. Summary of the Invention

In a first aspect the invention provides a lighting unit, the lighting unit comprising a substrate with a reflective surface, the substrate being formed of, or comprising, at least one channel section, the channel section comprising a major light source and a minor light source, the light sources being disposed in a corresponding respective major and minor groove formed in the channel section, the major and minor light sources within the same channel section being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel, characterized in that the light sources are selected from the group consisting of: an ultraviolet light source; and an infrared light source.

Preferably the light source, whether ultraviolet or infrared, is tubular. Tubular ultraviolet light sources are commercially available and typically comprise a UV-emitting fluorescent tube. Tubular IR light sources typically comprise an electrically conducting (but resistive) element such as a tungsten wire filament.

An "ultraviolet light source" is one which, as judged by the area under the curve for a graph of wavelength (nm) against relative intensity, emits at least 8% of its electromagnetic radiation in the ultraviolet range (100-400nm), preferably at least 10%, more preferably at least 12%, and most preferably at least 14, 16 or even up to 18%) or 20%) in the ultraviolet range. In some embodiments a preferred UV light source may emit 25, 30, 35, 40, 45 or even up to 50% of its radiation in the UV range.

An "infrared light source" is one which, as judged by the area under the curve for a graph of wavelength against relative intensity, emits at least 20% of its electromagnetic radiation in the infrared range (800ηηι-10μπι wavelength), preferably at least 30%>, more preferably at least 32%, and most preferably at least 34, 36 or even up to 38%) or 40%) in the infrared range. In some embodiments the preferred IR light source emits at least 50, 60, 70 or even up to 80% of its radiation in the IR range. Depending on the nature of the light source, it is not unusual for the emission spectra of light sources to contain several distinct peak wavelengths of emission. For example, a typical ultraviolet light source may comprise mercury vapour and characteristically has emission peaks at 253-255nm and/or 366nm, as well as other peaks at longer wavelengths.

In the present context, the projection between the major and minor light sources is opaque relative to most of the emission wavelengths of the light sources in question. In general, in any event, a material which is opaque to, for example, ultraviolet light will also be substantially opaque to infrared light.

The major light source and the minor light source may be different e.g. have different peak emission wavelengths. For example, one may be an infrared light and the other may be an ultraviolet light. More preferably however the two light sources will both be infrared, or both ultraviolet, as the case may be.

The preferred choice and characteristics of the light sources will depend on the intended application of the lighting unit.

In some embodiments, the light sources comprise an infrared light source having a peak emission wavelength in the range 1.0-5.0 μπι, preferably 1.5-2.8μιη, more preferably 2.2-2.8μιη.

For present purposes, the term "light" is used to describe any electromagnetic radiation in the infrared, visible or ultraviolet parts of the electromagnetic spectrum, and the terms "light source" and "lighting unit" should be construed accordingly. Where infrared (IR) or ultraviolet (UV) are specifically intended, the terms IR or IR light and UV or UV light may occasionally be employed. "Visible light" means light with a wavelength which is detectable by a typical human observer, which wavelength is generally in the range 400-750nm. A particular aim of the present invention is to provide a lighting unit providing IR or UV light with a low electrical power consumption. Another advantage of the lighting unit of the present invention is the uniformity of light output.

To achieve these aims, the present invention maximises the light output by having at least two light sources in each channel section of the lighting unit. Moreover, in order to reduce the problem of the light emitted by one of the light sources being absorbed by the other light source in the same channel section, the two light sources are separated by an opaque projection, the geometry of which is preferably devised to as to allow the light to exit from the channel section in the desired direction (e.g. outwards from the channel section). The lighting unit of the invention may comprise a plurality of channel sections, each of which comprises a major and a minor light source disposed within a respective major and minor groove, as described above.

The preferred design of lighting unit of the present invention provides light sources which have a light-emitting area that is greater than the area of the width of the channel through which light is emitted. In a preferred embodiment, the light sources emit light in a 360° plane along at least part of their length and may conveniently be substantially tubular. This emitted light is gathered and reflected by the reflective substrate towards the aperture of the channel section, such that there is an increase in the nominal luminous intensity of the light sources in the desired direction (e.g. out of the channel section and towards an intended target).

The channel section or sections may in some embodiments be substantially linear, but in other preferred embodiments the channel section or sections may be substantially annular or helical. Where a plurality of channel sections is present they may be preferably substantially identical in profile. A plurality of channel sections may conveniently be in a parallel array, but this is not essential and may depend on the intended purpose of the lighting unit. Desirably, in some embodiments, in order to maximise the radiant flux density (in terms of Watts per cm 2 ) output from the unit, adjacent channel sections should preferably be arranged with no spacing or gap between them, or as small a gap as is feasible, and preferably the channel sections form a regular parallel array. Advantageously, in the same or other embodiments, the or each channel section has a substantially linear, preferably vertical, side wall (i.e. the side walls are vertical when the substrate is laid horizontally). In the same or other embodiments, for economy of material, the side wall of one channel section is preferably shared with, or common to, an adjacent channel section. It will be apparent that the maximum external dimensions of the array may be selected according to the size of the lighting unit required for the intended purpose.

In some embodiments, light sources disposed in the channel sections may comprise curves or bends through 180° at the end of linear channel sections, so as to follow a continuous serpentine path through the channel sections. It is possible, but not necessary, that the channel sections may similarly comprise 180° bends at the end of the linear section, so that the channel equally follows a single, continuous serpentine path.

In a preferred embodiment, the lighting unit of the invention comprises at least one annular, or elliptical or helical channel section, with a correspondingly-shaped annular, elliptical or helical tubular light source within the respective major and minor grooves of the channel section.

Preferably, a highly reflective surface (such as a mirrored finish) is provided on the substrate to reflect light emitted from the light sources towards the aperture. The coating has a high reflectance (R), typically over 90%, and preferably a very high reflectance (over 95%). In preferred embodiments, the substrate is coated with a highly reflective coating comprising aluminium or (for IR units) gold. A preferred coating comprises a specular, bright-dipped, anodised aluminium 6000 series alloy, such as aluminium 6063. (By way of explanation, 6000 series aluminium alloys comprise aluminium alloyed with magnesium and silicon). Alloy 6063 is widely used as it has high malleability, but other 6000 series alloys are also suitable. A gold reflective coating may be preferred where the light source is an infrared light source.

Preferably the reflective surface is profiled so as to reflect towards the aperture at least some, (preferably most) of the light initially emitted from the tubes in directions other than towards the aperture. This further increases the proportion of the emitted light which reaches the aperture. The reflective surface may include curved portions for re-directing light emitted from the light sources towards the aperture. For example, the curved portions may define a parabolic surface profile in transverse cross-section.

Returning to the preferred features of the geometry of the channel sections and the disposition of the major and minor light sources within the channels, the substrate (typically formed of a synthetic plastics material, such as acrylonitrile butadiene styrene ["ABS"], or ABS polycarbonate blends, or the like) may conveniently be formed by extrusion moulding, or may be formed from extruded aluminium or an aluminium alloy. In a preferred embodiment, in cross-section, the channel section has a longitudinal major groove, accommodating a major light source, and a parallel longitudinal minor groove, accommodating a minor light source. The minor groove is shallower and thinner than the major groove. In addition, the minor groove is positioned higher than the major groove, and offset to one side. Conveniently part of one side wall of the major groove also forms part of one side wall of the minor groove, this being the projecting portion which at least partially separates the major and minor grooves. The major groove, in cross-section, may preferably be substantially goblet or tulip-shaped. The minor groove in cross-section may be substantially cup-shaped or semi-circular with one side wall of the groove being extended relative to the other side wall.

This arrangement is found to increase the amount of effective light-emitting surface area of the light source within the channel section (relative to the target plane aperture), whilst substantially minimising the amount of light which, emitted by one light source, is incident upon the other light source (and which might therefore be absorbed thereby).

Desirably, the channel section has a target plane aperture width (i.e. the width of the opening in the channel section through which light from the light sources exits the channel section) in the range 20-40mm, more especially in the range 20-35mm, but this may vary greatly depending on the intended purpose of the lighting unit. Other preferred widths in other embodiments are 70-80mm. The geometry and the reflective coating of the substrate acts as a light "concentrator" and director, by reflecting UV/IR light emitted from the UV/IR light sources within the channel section and directing it into a reduced cross-sectional area, thereby increasing the effective light intensity.

Conveniently both light sources are substantially tubular in cross-section along most or all of their length. Preferably the ratio of the diameter of the major light source to the diameter of the minor light source is in the range 1.3 : 1 to 1.7: 1, more preferably in the range 1.4: 1 to 1.6: 1. In one embodiment, the major light source has a diameter in the range 9- 13mm and the minor light source has a diameter in the range 6-8mm. More especially the major light source preferably has a diameter of about l l-12mm and the minor light source has a diameter of about 7-8mm. Other embodiments may have larger or smaller diameter light sources, but the ratio of the diameters noted above is conveniently preserved. In some particular preferred embodiments, a tubular UV light source has a diameter in the range 18-28mm (especially 18 or 28mm) and, in such embodiments, the target plane aperture width is desirably in the range 70-80mm.

As noted above, the lighting unit of the invention may be used with either ultraviolet or infrared light sources - and these are both described in further detail below.

Ultraviolet

Ultraviolet light sources are used for many different purposes and, by incorporation into the lighting unit of the invention, it is possible to increase the efficiency of the ultraviolet light source.

Ultraviolet light may be classified into different categories based on its wavelength. The ISO standard recognizes, inter alia, three different categories: UVA (wavelength 315-400nm), UVB (280-315nm) and UVC (100-280nm). Applications of UV include the following: wavelength (nm) Application

30-200 photolithography for manufacture of integrated circuits

230-365 scanning of bar codes; label tracking

240-280 disinfection; decontamination; germicidal uses

200-400 forensic analysis; drug detection

300-320 light therapy in medicine

300-365 curing of polymers and printer inks

350-370 UV insect traps

315-400 sunbeds, tanning booths

Sources of UV light include those contained in conventional mercury lamps, xenon arc lamps, deuterium arc lamps, mercury-xenon arc lamps, metal-halide arc lamps and tungsten-halogen incandescent lamps. Hand-held UV lamps are especially useful in forensic applications for examination of crime scenes, detection of forgeries and fakes, or authentication of documents, works of art etc. All of the foregoing are readily available commercially.

Any of the aforementioned UV light sources could be incorporated within the reflector subunit in order to construct a UV lighting unit in accordance with the invention. The lighting unit may comprise a single channel section, or may comprise a plurality of channel sections, optionally multiplexed in a regular array. UV light sources are available from many manufacturers. Examples include the Amba ® range and low- and medium-pressure mercury vapour lamps from Heraeus Noblelight (Cambridge Science Park, Milton Road, Cambridge, UK).

Infrared

As above, incorporation into a lighting unit in accordance with the invention increases the efficiency of an otherwise conventional infrared light source.

Industrial or technical uses of IR include thermal imaging and tracking, forming of synthetic plastics materials, annealing and plastics welding, curing of coatings and inks, and print drying. IR light sources are available from many manufacturers. Tubular IR light sources, in particular, are available from Heraeus Noblelight (Cambridge Science Park, Milton Road, Cambridge, UK). Preferred IR sources include tubular quartz IR lights.

Preferably the lighting unit of the invention further comprises the electrical components necessary to operate the UV or infrared light sources e.g. a driver or ballast, which may be present as an integral part of the lighting unit. Tubular UV or IR light sources suitable for use in the lighting unit of the invention are well-known to those skilled in the art. Further, the lighting unit may conveniently comprise conventional means for making electrical contact with an electrical power supply provided to the lighting unit. The power supply will typically be a mains power supply.

In one embodiment, a common voltage may be provided to both the major and the minor light sources in the channel section of the lighting unit. In other embodiments, a different voltage is applied to the two light sources: typically a larger voltage may be applied to the minor light source if the current through the minor and major light sources is equal. Alternatively the voltage across the light sources may be equal but with a larger current through the minor light source. In some embodiments, a common ballast or driver is provided with the lighting unit, which common ballast or driver is used to operate both the major and minor light sources, whilst in other embodiments the lighting unit may comprise a first driver or ballast to operate the major light source and a second driver or ballast to operate the minor light source. The person skilled in the art can arrive at a suitable arrangement of ballast or drivers and appropriate voltages and currents, with the benefit of the present disclosure, without requiring inventive effort.

As noted elsewhere, the lighting unit may comprise a plurality of channel sections, each channel section comprising a respective major and minor light source. In such embodiments, it may be desirable and feasible to provide a first common ballast or driver to operate two or more of the major light sources, and a second common ballast or driver to operate two or more of the minor light sources. An electrophoretic process may conveniently be used to apply the reflective coating to the substrate. If the substrate is conducting (e.g. aluminium or aluminium alloy), then the process is straight forward. If however, a plastic substrate is used this is not electrically conductive to a sufficient extent, and as an initial step therefore the plastics substrate must first be coated with a conductive layer. This is conveniently achieved by a "plating on plastics" (POP) process, which is known to those skilled in the art. Thereafter, the substrate (e.g. the synthetic plastics substrate chassis) is made the cathode and positively charged aluminium ions are reduced to aluminium metal on the substrate. Once coated with specular aluminium (or, optionally, gold, in the case of a reflector for an IR source), the coated chassis is then preferably subjected to a "bright dipping" process, which increases the brightness or reflectance of the aluminium by reducing, at a microscopic level, the roughness of the surface by reducing the "peaks" thereof. Most commercially available bright dipping procedures involve the use of dip baths comprising a mixture of phosphoric and nitric acids. Various additives may be included to reduce the amount of nitrogen oxide fumes produced and to enhance the brightening ability of the bath.

The lighting unit of the invention may be incorporated into a light or lamp. In some embodiments the light or lamp is a hand-held portable device. In some embodiments the light or lamp is configured to operate using one or more batteries as the primary power source, especially if the device is hand-held and portable. Desirably the batteries are rechargeable. In non hand-held contexts, where weight considerations are less important, preferred rechargeable batteries comprise lithium iron phosphate (LiFeP0 4 ) batteries, such as those commercially available from pbq batteries. In some embodiments the batteries may be recharged by connection to a mains power supply.

In a further aspect the invention provides a method of making a lighting unit in accordance with the first aspect of the invention, the method comprising the step of: assembling, in operable relationship: a substrate with a reflective surface, the substrate being formed of, or comprising, at least one channel section; and a major light source and a minor light source, said light sources being disposed in a corresponding respective major and minor groove formed in the channel section, the major and minor light sources within the same channel section being at least partially separated by an opaque projection therebetween, such that light output from one of the light sources is substantially prevented from being incident on the other light source in the same channel, and characterized in that the light sources are selected from the group consisting of: an ultraviolet light source; and an infrared light source.

The preferred features of the lighting unit are as described above, and performance of the method of the invention preferably results in the production of a lighting unit having one or more of the aforesaid preferred features.

The invention will now be further described by way of illustrative example and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of one embodiment of a substrate for a lighting unit in accordance with the invention;

Figure 2A is a side view of the embodiment of the substrate shown in Figure 1; Figure 2B is a detail of an enlargement of part of the substrate shown in Figure 2A; Figure 2C is an enlargement of the part shown in Figure 2A;

Figures 3a and 3b are illustrations of an embodiment of a lighting unit in accordance with the invention;

Figures 4a and 4a are illustrations of an embodiment of a lighting unit in accordance with the invention in perspective view and exploded view respectively, the lighting unit comprising a multiplex array of four channel sections;

Figures 5a and 5b are a perspective view and a transverse sectional view respectively of an embodiment of a lighting unit in accordance with the invention, in which two channel sections are provided as a multiplex array in a mirrored or "back to back" arrangement; Figures 6a, b and c are illustrations of a light fitting comprising a lighting unit in accordance with the first aspect of the invention: Figure 6a is a perspective view from above, Figure 6c is a perspective view from below, and Figure 6b is a median transverse sectional view;

Figures 7a-7c are illustrations of a further embodiment of a light fitting comprising a lighting unit in accordance with the first aspect of the invention: Figure 7a is a perspective view from above, Figure 7c is a perspective view from below, and Figure 7b is a median transverse sectional view;

Figures 8a-8d are illustrations of yet a further embodiment of a light fitting comprising a lighting unit in accordance with the invention: Figure 8a is a plan view from below, Figure 8b is a section along the line A-A in Figure 8a, Figure 8c is a plan view from above and Figure 8d is a perspective view from above;

Examples

Example 1 - substrate for use in a lighting unit in accordance with the invention.

Referring to Figure 1, a preferred substrate (2) is formed from extruded plastics material, such as ABS or ABS polycarbonate mix. (In other embodiments the substrate may be formed from extruded aluminium or an aluminium alloy). The substrate comprises a plurality of linear channel sections (4) arranged in a parallel array. The entire upper surface of the substrate is coated with a highly reflective specular coating of bright-dipped, anodised aluminium 6063 alloy. The channel sections are arranged in the array with little or no gap between adjacent channel sections, in order to maximise the intensity of light output from the panel. The external dimensions of the array are determined according to the size of lighting panel required.

As best seen in Figures 2A & 2B, each channel section (4) comprises a major longitudinal groove (6) and a parallel minor longitudinal groove (8), which are partially separated by a projecting portion (10), which forms part of one side wall of the major groove (6) and most or all of one side wall of the minor groove (8). The major groove (6) and the minor groove (8) accommodate, in the completed lighting panel, a respective major light source and minor light source (not shown in Figures 2A, 2B). The light sources may be IR or UV tubular light sources.

Each channel section 4 comprises a pair of side walls (12), which side walls are shared with the adjacent channel section on each side. The side walls (12) are vertical when the substrate is laid horizontally, as shown in Figs. 1-2.

In the embodiment shown, the major groove (6), at its widest point, is 22.5mm. The minor groove (8), is 12.0mm wide at its widest. The target plane aperture ("w" in Figure 2B) of each channel section is 28.5mm wide. The major groove (6) accommodates a circular cross-section light source which is l l-12mm in diameter. The minor groove (8) accommodates a circular cross-section light source which is 7-8mm in diameter. In other, similar, embodiments the major groove accommodates a tubular light source (especially a tubular UV light source) of 28mm diameter and the minor groove accommodates a tubular light source (especially a tubular UV light source) of 18mm diameter (the light source diameters being in the ratio of 1.55: 1). In such embodiments the target plane aperture width (w) is desirably in the range 70- 80mm.

The minor light source is centred above and to one side of the major light source, with the opaque projecting portion (10) therebetween. This arrangement entirely, or almost entirely, prevents light emitted from one light source being incident upon the other light source in the same channel section, thereby minimising light lost due to absorption by the light sources.

The light sources preferably have a surface area considerably greater than the area of the channel section through which they emit. Thus, if one considers a very thin 1mm transverse "slice" through the display panel, the area of the aperture of the channel is 28.5mm 2 . The light-emitting surface area of the major tubular light source is given by the formula for the circumference of a circle (c= d). Assuming the diameter of the tube to be 11.5mm, the area of the 'slice' of tube is 36.1mm 2 . The light emitting area of the minor tubular light source (assuming a diameter of 7.5mm 2 ) is 23.6mm 2 , so the combined light emitting area of the light sources is 59.7mm 2 . Even allowing for absorption of some light by the reflective substrate and by the tubes themselves, it is clear that the apparent intensity of the light sources, in the direction of the channel section aperture, is significantly increased.

The detailed geometry of the preferred embodiment of the reflective substrate is apparent in Figure 2C, which is an enlargement of the embodiment shown in Figure 2, showing the dimensions of various features (in mm), from 0-4 lmm in height (scale on the left hand of the drawing) and from 0-29mm in width (scale at the top of the drawing), together with the measurements of selected angles and radii of curvature. The positions of the minor and major tubular light sources within their respective grooves are indicated by broken lines.

In the illustrated embodiment, the radiant flux or radiant power (measured in Watts or Joules per second) of each channel in the reflective substrate is determined according to the equation (1):

Radiant Flux (Watts) = + d?L?) x R

w w where

di = diameter (mm) of major UV/IR tube

d 2 = diameter (mm) in minor UV/IR tube

Li = radiant flux output (in Watts) of major UV/IR tube

L 2 = radiant flux output (in Watts) of minor UV/IR tube

w = target plane aperture width (mm) [indicated by "w" in Figure 2B) and R = the output coefficient of the total system (estimated as being approx.

70-80 %, leading to a 1.4-1.5x gain on the initial luminance) The Applicant has found that the illustrated embodiment provides a UV or IR lighting unit with a significantly reduced power consumption.

Example 2

This example relates to a portable hand-held light device in accordance with the invention. The device has low power consumption and comprises rechargeable batteries.

The batteries may be recharged by connecting them to a mains supply or other external electrical energy supply. The hand-held device preferably comprises UV light sources and may be used, for example, in a laboratory or at a crime scene or for any other purpose for which a UV light or lamp is conventionally employed.

Example 3

Figures 3a and 3b show a perspective view and an exploded view respectively of one embodiment of a lighting unit in accordance with the invention. The lighting unit comprises a housing 100 accommodating a substrate e.g. of extruded aluminium. The substrate comprises a single channel section 4, which comprises a major longitudinal groove 6 and a parallel minor longitudinal groove 8, separated by a projecting portion 10, which forms part of one side wall of the major groove 6 and most or all of one side wall of the minor groove 8. The major groove 6 and the minor groove 8 accommodate a respective major and minor light source which, in this embodiment, are ultraviolet light tubes.

The entire upper surface or the substrate is coated with a highly reflective specular coating of bright-dipped, anodized aluminium 6063 alloy.

In the illustrated embodiment, the light fitting comprises a single channel section, but in other embodiments the light fitting may comprise a plurality of channel sections. Where a plurality of such sections is provided, they may be formed in a regular array or multiple with little or no gap between adjacent channel sections, in order to maximize the intensity of light output from the fitting. The external dimensions of the array are determined according to the size of light fitting required. In one embodiment the channel sections may all be facing the same way (see Figures 4a and 4b). In other embodiments, the channel sections may be "back-to-back", as shown in Figures 5a and 5b.

Referring again to Figures 3a and 3b, the lighting unit comprises a cap 102 at each end of the channel section. The cap provides electrical contacts to provide electrical power to the lighting unit (e.g. from a mains electrical supply) and conventional electrical driver components (e.g. a "ballast") to run the ultraviolet light tubes.

A further embodiment of a light fitting in accordance with the invention is shown in Figures 6a-6c.

This embodiment is very similar to that shown in Figures 3a and 3b except that, rather than being linear, the channel section 4 is circular, with the major and minor grooves and the major and minor ultraviolet light tubes being correspondingly shaped. Equally the housing 102 is essentially circular or annular to accommodate the channel section. In this embodiment, the electrical contacts and components may be provided in the centre of the housing.

Yet another embodiment of a light fitting is illustrated in Figures 7a-7c. This embodiment is, in essence, a multiplexing of the embodiment shown in Figures 6a-6c. In this multiplexed embodiment, there are four circular channel sections positioned vertically in a stack, one on top of another.

Example 4

This example relates to a light fitting comprising a lighting unit in accordance with the invention, which light fitting is especially useful for, and adapted and configured for use as, a downlighter, especially a ceiling-mounted downlighter. Such a light, provided with ultraviolet light sources, could be useful for disinfection of laboratories or other workspaces where disinfection is required.

The embodiment is illustrated in Figures 8a-8d. Figure 8a shows a plan elevation of the embodiment from the underside. Figure 8b shows a sectional view through the fitting along the section indicated A-A in Figure 8a. Figure 8c shows a plan elevation of the embodiment from above, and Figure 8d shows a perspective view of the embodiment from above.

Referring to the Figures, the light fitting comprises a lighting unit in accordance with the first aspect of the invention. Topologically, the light fitting comprises only one channel section, but this follows a tightly wound planar spiral or helical pattern so as to form, in effect, an array of a plurality of channel sections adjacent one another, as best seen in Figure 8b (with seven channel sections each side of the spiral). As previously, the channel section comprises a major groove and a smaller, offset, minor groove, each of the grooves accommodating a respective major and minor fluorescent light tube.

The opposed ends 200, 202 of the ultraviolet light tubes are visible in Figure 8a at the outside (200) of the spiral and at the inside (202) of the spiral. As best seen in Figure 8d, the ends 200 and 202 are curved upwards above the plane of the spiral and terminate with a transverse support 204 which spans, on one side, from the centre of the spiral to its outer arm. The transverse support includes electrical terminals and connections to accept power from a mains electrical power supply and to transfer the electrical power to the UV light tubes. The support 204 is also provided with a ballast/starter to operate the tubes, along with any other electrical components necessary for the light fitting to operate.

The whole fitting may, in operation, be covered with a protective UV-transparent or translucent cover, comprised of glass or synthetic plastics material (e.g. polycarbonate).




 
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