WO2018049469A1

WO2018049469A1 - Extended service life lighting assembly

Info

Publication number: WO2018049469A1
Application number: PCT/AU2017/050993
Authority: WO
Inventors: Phillip Anthony Bosua
Original assignee: Raai Lighting, Inc
Priority date: 2016-09-15
Filing date: 2017-09-14
Publication date: 2018-03-22

Abstract

The present invention provides an extended service life lighting assembly comprising two or more light emitting diodes, wherein the lighting assembly is configured such that each of the two or more of the light emitting diodes is independently activatable, or controllable with respect to a parameter capable of extending the service life of the lighting assembly. The activation or control may programmed or scheduled by electronic means. The parameter capable of extending the service life of the lighting assembly may be light output energy. The lighting assembly may comprises a controller configured to independently control each of the two or more light emitting diodes with respect to the parameter capable of extending the service life of the lighting assembly. In some embodiments, the activation or control is based on an alteration in an electrical parameter of one of the two or more diodes such as voltage, current and resistance.

Description

EXTENDED SERVICE LIFE LIGHTING ASSEMBLY

FIELD OF THE INVENTION

The present invention relates to lighting devices of the type used in domestic, office, light industrial and commercial applications.

BACKGROUND TO THE INVENTION

The development of light emitting diode (LED)-based lighting has provided consumers with many advantages such as decreased power consumption, the ability to regulate the color of light output and an increase in service life. Present LED-based light bulbs offered for domestic applications typically claim a service life of around 25,000 to 50,000 hours. In reality, LED light output deteriorates significantly well before the end of a claimed service life.

In some environments the service life of an LED light bulb can be diminished compared with a bulb operated in a relatively normal environment. For example, diodes exposed to excess heat, vibration, shock, voltage spikes, repeated switching on and off will deteriorate prematurely.

The prior art attempts to improve the service life of an LED light bulb has mainly been by way of thermal management so as to protect the diodes from excessive heat. This is often achieved by ensuring the provision of sufficient heat sinking and ventilation so as to conduct away thermal energy. Such measures are limited to making incremental improvements to service life. Where the power supply is problematic, a silicon diode cap can be attached to the base of the bulb to reduce the voltage passing through. However, by lowering voltage the light output is compromised to some extent.

For some applications, the diminution of light output can have negative functional effects. For example, where an LED light is used for antimicrobial purposes (such as the disinfection of a fomite or a surface) the efficacy of microbe killing is decreased where light output is diminished. Thus, actual microbe killing levels may be lower than that expected, and infection of a person or animal may result. In any event, it is generally desirable to increase the service life of an LED light bulb. It is an aspect of the present invention to overcome or alleviate a problem of the prior art by providing an extended service life LED light bulb. It is a further aspect of the invention to provide an alternative to prior art LED light bulbs. The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

SUMMARY OF THE INVENTION

In a first aspect, but not necessarily the broadest aspect the present invention provides a lighting assembly comprising two or more light emitting diodes, wherein the lighting assembly is configured such that each of the two or more of the light emitting diodes is independently activatable or controllable with respect to a parameter capable of extending the service life of the lighting assembly.

In one embodiment of the first aspect, the activation or control is programmed or scheduled by electronic means.

In one embodiment of the first aspect, the parameter capable of extending the service life of the lighting assembly is light output energy.

In one embodiment of the first aspect, the lighting assembly comprises a controller configured to independently control each of the two or more light emitting diodes with respect to the parameter capable of extending the service life of the lighting assembly.

In one embodiment of the first aspect, the independent activation or control is based on a light output parameter of at least one of the two or more light emitting diodes.

In one embodiment of the first aspect, the light output parameter is light output energy, light output quality, stability in light output energy, or stability in light output quality.

In one embodiment of the first aspect, the independent activation or control is based on absolute time or an elapsed time. In one embodiment of the first aspect, the absolute time is obtained by of internet connection between the light assembly and a server configured to output absolute time.

In one embodiment of the first aspect, the light assembly is configured to modulate light output of at least one of the two or more light emitting diodes over a time period, or at a predetermined time.

In one embodiment of the first aspect, the activation or control is based on an alteration in an electrical parameter of one of the two or more diodes.

In one embodiment of the first aspect, the electrical parameter is selected from the group consisting of voltage, current and resistance.

In one embodiment of the first aspect, each of the two or more light emitting diodes is mounted on a separate heat sink.

In one embodiment of the first aspect, each of the two of more light emitting diodes is part of a functional group of diodes, and wherein each functional group is independently controllable with respect to a parameter capable of extending the service life of the lighting assembly.

In one embodiment of the first aspect, the light assembly comprises two, three, four, five, six, seven, eight, nine or ten functional groups.

In one embodiment of the first aspect, each functional group comprises two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, 14, fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty-one, twenty-two, twenty-three, or twenty-four light emitting diodes.

In a second aspect of the present invention there is provided a method for extending the service life of a lighting assembly comprising two or more light emitting diodes, the method comprising the step of independently activating or controlling the each of the two or more diodes with respect to a parameter capable of extending the service life of the lighting assembly.

In one embodiment of the second aspect, the step of independent activation or control is by way of a program or a schedule. In one embodiment of the second aspect, the parameter capable of extending the service life of the lighting assembly is light output energy.

In one embodiment of the second aspect, the step of controlling is executed by a controller configured to independently control each of the two or more light emitting diodes with respect to the parameter capable of extending the service life of the lighting assembly.

In one embodiment of the second aspect, the independent activation or control is based on a light output parameter of at least one of the two or more light emitting diodes.

In one embodiment of the second aspect, the light output parameter is light output energy, light output quality, stability in light output energy, or stability in light output quality.

In one embodiment of the second aspect, the independent activation or control is based on absolute time or an elapsed time.

In one embodiment of the second aspect, the absolute time is obtained by of internet connection between the light assembly and a server configured to output absolute time. In one embodiment of the second aspect, the method is configured to modulate light output of at least one of the two or more light emitting diodes over a time period, or at a predetermined time.

In one embodiment of the second aspect, the activation or control is based on an alteration in an electrical parameter of one of the two or more diodes.

In one embodiment of the second aspect, the electrical parameter is selected from the group consisting of voltage, current and resistance. BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram of an electrical circuit of a preferred lighting assembly of the present invention. DETAILED DESCRIPTION OF THE INVENTION

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and from different embodiments, as would be understood by those in the art.

In the claims below and the description herein, any one of the terms "comprising", "comprised of" or "which comprises" is an open term that means including at least the elements/features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a method comprising step A and step B should not be limited to methods consisting only of methods A and B. Any one of the terms "including" or "which includes" or "that includes" as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, "including" is synonymous with and means "comprising".

It is not represented that any embodiment disclosed herein has all advantages disclosed herein. Some embodiments may have a single advantage while others may represent merely a useful alternative to the prior art. The present invention is predicated at least in part on Applicant's finding that the service life of a LED light bulb can be increased by providing multiple diodes, with each of the diodes being independently controllable. In a prior art LED globe, all diodes (or all diodes of the same colour where multiple color diodes are used) are controlled as a single functional unit. Thus, in a prior art LED globe the diodes function to output light at all times and at maximum output level for the period that the bulb is switched on. By contrast, a lightbulb of the present invention holds at least one diode substantially operational at maximal level (or near maximal level) for a period of time (which may be measured in sub-seconds, seconds, minutes, hours, days, weeks, months or years), and another diode substantially non-operational (or near minimal level) for a period of time (which may be measured in sub-seconds, seconds, minutes, hours, days, weeks, months or years). In this way, the light output capacity of one diode is essentially held in reserve until a time that the light output of the other diode is compromised (due to it being at or near the end of its service life). Thus, when one diode is at or near the end of its service life, the reserve diode is powered leading to an extension of service life of the bulb. Alternatively, the switching from operation to non-operational between two diodes may be to extend the service life of each diode due to each diode is being operational only a portion of the time for which the entire device is operational and emitting light.

For example a light bulb may comprise a first diode and a second diode, with each of the two diodes having an expected service life of 25,000 hours. When the bulb is first powered on (for example, when the bulb is newly installed), only the first diode is operational to provide light output. The second diode is non-operative. The first diode continues to provide the only source of light output until the end of its service life, at which time the second diode is powered to provide the only source of light output for the bulb. Thus, the bulb has an effective service life of 50,000 hours (25,000 plus 25,000 hours). As will be appreciated, adding a third diode provides a service life of 75,000 hours and a fourth diode provides a service life of 100,000 hours.

A similar extension to bulb service life to may be achieved whereby the light output is provided alternately by the first diode and then second diode and then the first diode, and then the second diode, and so on. Thus, when the globe is first powered on the first diode is activated to provide all of the light output. When the globe is powered off and then powered on for a second time the second diode is activated to provide all of the light output. Upon a third power off - power on cycle the first diode provides all of the light output, et cetera. In this way, each diode is powered on for only approximately one-half of the time that the light bulb is powered on. Accordingly, the light bulb will have a service life of around double the service life of each individual light bulb. Where four diodes are provided, each diode is operational for only one out of four power cycles.

It is not necessary for the first and second diodes to assume either a completely off or completely on state in order to extend service life. For example, the first diode may output 75% of the overall light output by the bulb, and the second diode outputs 25% of the overall light. At a later time point, the second diode may output 75% of the overall light output by the bulb, and the first diode outputs 25% of the overall light. The diodes may continuously cycle between 25% and 75% total light output in a synchronised manner such that the overall output of the bulb is steady at 100%.

In some embodiments, it is preferable that the second diode remains completely unused until the first diode is at the end of its service life. As will be appreciated, the second diode may not be activated for several years or many years. In such embodiments the present lighting assembly includes means to automatically activate the second diode. This automatic activation may be triggered by a decrease in the light output of the first diode. This decrease in output may be sensed by a light sensor in the bulb, or by some other means such an alteration in power consumption of the diode, alteration of temperature in the diode, or alteration of resistance across the diode for example. Alternatively, alterations in the colour of the first diode (which can be an indicator of failure) may be detected by optical means thereby triggering activation of the second diode.

In some embodiments, there is no sensing function required to trigger the second diode. The bulb may be configured to activate the second diode after operation of the first diode for a predetermined period of time. Where the first diode is rated for 25,000 hours and the manufacturer estimates use of around 4 hours per day, the bulb may be configured to switch to the second diode after 6,250 hours of operation of the first diode. A margin for error may be introduced such that the second diode may be activated after, say 5,000 hours of operation of the first diode.

In one embodiment, the hours of operation of the first diode may logged by way of a timing circuit incorporated into the light bulb. The hours may be cumulatively logged and stored in a non-volatile memory module of the bulb. The hours of operation of the first diode may be estimated by reference to absolute time. Some embodiments of the light bulb may be configured so as to access the Internet (for example by means of an on-board WiFi module) and therefore receive time and date information from a service such as the Internet Time Service provided by the National Institutes of Standards and Technology of the United States Government Department of Commerce. Upon first powering on the bulb the current date may be retrieved from the Internet. A processor of the bulb may calculate the date, say, 10 years in advance and store that date in a non-volatile memory module of the bulb. Upon each power on cycle of the bulb the current date is retrieved form the Internet and compared to the date stored in the nonvolatile memory. If the current is the same or later than the stored date then the second diode is activated. The hours of operation of the first diode may be estimated by reference to elapsed time. In one embodiment, the first power on cycle of the bulb may trigger an electronic count-up or count-down clock which operates continuously. The electronic clock may be powered by mains power when available, and when not available by battery power. The battery may be rechargeable from the mains power.

The hours of operation of the first diode may be estimate by reference to the power on/off cycles applied to the bulb. In one embodiment, the bulb may comprise an electronic counter configured to count the number of times the light is powered on. The manufacturer may estimate that the globe is powered on for two hours each cycle, thereby providing some indication of the time for which the first diode is operational. In one embodiment, the first power on cycle of the bulb may trigger an electronic count-up or count-down clock which operates continuously. The electronic clock may be powered by mains power when available, and when not available by battery power. The battery may be rechargeable from the mains power.

Alternatively, the number of power on/off cycles may be provide an indication of the number of days for which the bulb has been in operation. The manufacturer may estimate that a bulb is typically cycled on/off twice per day. An electronic counter as described supra may be utilised in this embodiment.

A light assembly of the present invention may comprise an integrated circuit (optionally with processor capabilities) to independently control the diodes. Each diode may be switched on or off or otherwise modulated according to an algorithm stored in non-volatile memory in operable connection with the processor.

The light bulb may be configured such that the first diode may be fully deactivated (and non- operational) once the second diode is activated so that the light output from the bulb is not excessive. The deactivation may be active (such as by active switching) or passive (by way of current drawn preferentially to an operational diode.

In some embodiments of the invention, switching from a first diode to a second diode is not reliant on any electronic controlling means such as an integrated circuit, electronic clock or internet connectivity. The diodes may be connected using combinations of electronic components such as diodes (not light emitting), resistors, capacitors, transistors, relays, inductors, switches, transistors and the like, such that failure (or impending failure) of a first diode triggers activation of a second diode. Failure or impending failure of a first diode may alter current, resistance, voltage or other parameter within or about the first diode in the circuit, the alteration leading to a switching of power from the first diode to the second diode. The switching may be active or passive in nature.

As will be understood, reference to a diode may be extrapolated to mean a functional group of diodes. For example the bulb may comprise a first group of diodes which operate for 20,000 hours after which light output is provided by a second group of diodes.

In some embodiments, the light emitting diodes of the light assembly may emit energy that is deleterious to microbial life. For example, the light emitting diodes may emit ultraviolet (UV) radiation capable of damaging cellular DNA. Without wishing to be limited by theory in any way, the light energy causes a reaction between two thymine molecules (thymine being one of the nucleotide bases that makes up DNA). The longer the exposure to UV light, the greater number of thymine dimers formed in the DNA, this leading to disruption of normal cellular functions. Upon exposure to sufficient UV radiation, the cell will die. Thus, cellular microorganisms such bacteria, fungus, yeasts, and mycoplasma may be killed by exposure. Some non-cellular infectious agents (such as viruses) may also be negatively impacted by UV radiation.

These embodiments of the invention may be used to disinfect hard objects such as work surfaces, a fomite (such as a utensil, cup, a comb, item of clothing, phone, pen, book, toy etc), air, or a liquid. Given that such antibacterial light assemblies may be used constantly (and not just during dark periods), the benefits of extended service life are evident.

Moreover, advantage is also provided in the applications given the ability to maintain a relatively high level of UV radiation over time, and without substantial diminution of output. Thus, embodiments of the present light assemblies that have an antimicrobial function will retain a minimum level of microbe killing efficacy for longer periods. Indeed, these embodiments may be configured to switch from a first diode to a second diode when antimicrobial radiation output drops below a threshold level.

As shown infra, a light assembly having a peak output of 405nm was shown to be capable of rapidly killing bacteria commonly found in a domestic environment and on a fomite. Accordingly, the present light assemblies are contemplated to be useful in domestic, office and industrial environments for infection purposes.

The extended service life of the present light assemblies provides advantage in such disinfection applications given that the best bactericidal effect is provided where the light is continuously emitted. In a prior art light assembly, the much shorter service life would require changing of the light assembly at much more frequent intervals, especially where a minimum light energy output is required for efficacious disinfection. The present light assemblies may be configured to monitor light output to ensure at least a minimum level of antibacterial radiation is being emitted, and where the level decreases below that minimum then a new diode (or diodes) within the assembly may be switched on to either replace the existing diode or augment the output of the exiting diode.

Accordingly, in one aspect of the invention there is provided a method of disinfecting an object or the air, the method comprising the steps of providing a light assembly according to any embodiment of the invention (an particularly embodiments having peak light output in the violet or ultraviolet regions of the spectrum) and allowing the object or the air to be exposed to the energy output of the light assembly. The LEDs may have a peak output at any wavelength between about 100 nm to about 400 nm. Preferably, the wavelength is in the UVB or UVA regions (i.e. between about 280 nm, and about 400 nm). More preferably, the wavelength is in the UVA region (i.e. between about 315 nm and 380 nm). It has been found that sound bactericidal effects result where diodes have a peak output of around 400 nm, and even where the diode is surrounded by a titanium bis (ammoniumlactato)dihydroxide phosphor. The phosphor corrects the violet output of the 400 nm diode toward white light output. Accordingly, this light assembly has the advantages of (i) long service life (ii) microbiocidal activity and (iii) a more useful white light output.

A light assembly of the present invention may be constructed in the form of a light bulb according to any of the well known arrangements of the prior art including a socket connector, a base, thermal pottants, thermally conductive encapsulants. Thermal interface materials, heat sinking materials (optionally formed into fins), reflector materials, phosphors, diffusers, a driver IC, transformers and the like. In one embodiment, the bulb is configured so as to limit transfer of heat generated by the operation of the first diode to the second diode. In the absence of such configuration, over years of operation of the first diode the second diode may become degraded by heat leading to a shortened service life of the second diode. This problem of heat degradation of diodes is exacerbated for a third diode (being exposed sequentially to heat originating from both the first and second diodes) and even further exacerbated for a fourth diode (being exposed sequentially to heat originating from the first, second and third diodes). Each diode may be mounted on a separate heat sink such that it is subject mainly to heat occasioned on it by virtue of its own operation. Various heat insulating materials may also be used to inhibit the transference of heat to a non-operational (reserve) diode. Further steps may be taken such as to ensure heat generating wiring or componentry is thermally isolated from the diodes.

The present invention will now be more fully described by reference to the following non- limiting preferred embodiment.

PREFERRED EMBODIMENTS OF THE INVENTION

Lighting Assembly having four independently controllable functional groups. Reference is made to the schematic diagram shown in FIG. 1 , showing a highly preferred lighting assembly of the present invention. The schematic is intended to be applied to a self- contained LED light bulb for domestic or office use.

The LEDs SZ5-M1 -WW-00 (Seoul Semiconductor) were chosen in part for thermal properties (ThetaJa = 4.5C/W). The LEDs were arranged into four groups of twelve, as shown. Each group is considered a functional unit and the assembly configured such that the individual functional units are alternately operable to emit light such that sequential activation of the four functional units provides a service life of at least 100 years based on 4 hours use per day. Arranged as multiple individual series strings, there may be 8 opens before the light output drops to 50%, and 16 opens before there is no light emitted. Each string is proposed to have a service life of 25 years. Shunt protection is provided (LSP1800; Bourne USA) such that if an entire functional group of LEDs fails, the remaining functional groups will nevertheless function. Transient voltage diodes (5KP; Littlefuse, Chicago) ensure that LEDs will conduct minimal current where any electrostatic discharge in a functional unit.

The assembly comprises a continuous copper backing plate for the LEDs, venting in the casing and heat dissipation fines (not shown). Power is supplied by way of LT3799 Triac dimmable off-line isolated LED driver with PFC (Linear Technology, Milpitas CA)

Each group of LEDs is connected to the successive group in parallel through a diode. When the first group of LEDs is conducting electricity, the total voltage drop is lower than the next group with the additional diode. When the first group fails open, the current source powering the group will push the voltage high enough to forward bias the diode between the first and second groups and the second group will conduct (and therefore emit light). As each group fails to open, the total voltage for the functional group increases by the forward voltage drop of the connecting diodes in-between the successive LED strings. As stated above, when all LEDs in a functional group fail open, the current will continue to power the remaining functional groups through the shunt protection (LSP1800).

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Antimicrobial Light Assembly This embodiment is identical to that described immediately supra, although utilizes 405nm LED for output. This wavelength is toward the limits of the light spectrum visible to humans, and is perceived as violet. The violet light output was corrected using titanium bis (ammoniumlactato)dihydroxide (TBD) phosphor coated onto the LED die. Antibacterial Efficacy of Antimicrobial Light Assembly. The light assembly described supra (having a 405nm peak output) was tested for its ability to inactivate common bacteria. Three inocula were tested:

• Inoculum A - mixed bacterial swabbed from a cell phone case. Both Gram positive and Gram negative bacteria expected, including species normally resident on the human hand such as Staphylococcus spp, propionibacteria, corynebacteria, dermobacteria, and micrococci.

• Inoculum B - mixed bacteria swabbed from a domestic kitchen counter. Both Gram positive and Gram negative bacteria expected, including Enterobacter spp. and

Pseudomonas spp.

• Inoculum C - mixed bacteria swabbed from a domestic toilet seat. Both Gram positive and Gram negative bacteria expected, including faecal conforms, such as E.Coli.

Each inoculm A, B and C was separately plated onto replicate Trypticase Soy Agar plates. A control plate for each inoculum was placed on a bench under natural lighting conditions, while experimental plates were exposed to the 405nm lighting assembly for a time period of 10 mins, 1 hour, 6 hours or 24 hours.

All plates were subsequently incubated at 37 degrees until colonies formed.

Results for the control plates showed that inoculum A and inoculum C contained colonies of varying morphologies, suggesting the presence of multiple bacterial species. In both cases, the colonies were too numerous to count. Inoculum B contained colonies several different morphologies, but at countable numbers (typically between 5 and 10).

After 10 minutes exposure to the 405 nm light, significant reductions in colony forming units (CFU) were note for inocula A and C. While not enumerated, approximately 90% reduction compared with control plates was noted. Reductions in CFU were noted also for Inoculum B, with numbers reduced to typically 1 to 3 CFU.

After 24 hours exposure, almost complete killing was noted for all inocula. In the following claims, any of the claimed embodiments can be used in any combination.

Claims

CLAIMS:

1 . A lighting assembly comprising two or more light emitting diodes, wherein the lighting 5 assembly is configured such that each of the two or more of the light emitting diodes is independently activatable, or controllable with respect to a parameter capable of extending the service life of the lighting assembly.

2. The lighting assembly of claim 1 wherein the activation or control is programmed or o scheduled by electronic means.

3. The lighting assembly of claim 1 or claim 2 wherein the parameter capable of extending the service life of the lighting assembly is light output energy. 5 4. The lighting assembly of any one of claims 1 to 3 wherein the lighting assembly comprises a controller configured to independently control each of the two or more light emitting diodes with respect to the parameter capable of extending the service life of the lighting assembly. 0 5. The lighting assembly of any one of claims 1 to 4 wherein the independent activation or control is based on a light output parameter of at least one of the two or more light emitting diodes.

6. The lighting assembly of claim 5 wherein the light output parameter is light output5 energy, light output quality, stability in light output energy, or stability in light output quality.

7. The lighting assembly of any one of claims 1 to 6 wherein the independent activation or control is based on absolute time or an elapsed time. 0 8. The lighting assembly of claim 7 wherein the absolute time is obtained by of internet connection between the light assembly and a server configured to output absolute time.

9. The lighting assembly of any one of claims 1 to 8 configured to modulate light output of at least one of the two or more light emitting diodes over a time period, or at a

5 predetermined time.

10. The lighting assembly of any one of claims 1 to 9 wherein the activation or control is based on an alteration in an electrical parameter of one of the two or more diodes.

1 1 . The lighting assembly of claim 10 wherein the electrical parameter is selected from the group consisting of voltage, current and resistance.

12. The lighting assembly of any one of claims 1 to 1 1 wherein each of the two or more light emitting diodes is mounted on a separate heat sink. 13. The lighting assembly of any one of claims 1 to 12 wherein each of the two of more light emitting diodes is part of a functional group of diodes, and wherein each functional group is independently controllable with respect to a parameter capable of extending the service life of the lighting assembly. 14. The lighting assembly of claim 13 comprising two, three, four, five, six, seven, eight, nine or ten functional groups.

15. The lighting assembly of claim 13 or claim 14 wherein each functional group comprises two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, 14, fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty-one, twenty-two, twenty-three, or twenty-four light emitting diodes.

15. A method for extending the service life of a lighting assembly comprising two or more light emitting diodes, the method comprising the step of independently activating or controlling the each of the two or more diodes with respect to a parameter capable of extending the service life of the lighting assembly.

16. The method of claim 15 wherein the step of independent activation or control is by way of a program or a schedule.

17. The method of claim 15 or claim 16 wherein the parameter capable of extending the service life of the lighting assembly is light output energy.

18. The method of any one of claims 15 to 17 wherein the step of controlling is executed by a controller configured to independently control each of the two or more light emitting diodes with respect to the parameter capable of extending the service life of the lighting assembly.

19. The method of any one of claims 15 to 18 wherein the independent activation or control is based on a light output parameter of at least one of the two or more light emitting diodes.

20. The method of claim 19 wherein the light output parameter is light output energy, light output quality, stability in light output energy, or stability in light output quality.

21 . The method of any one of claims 15 to 20 wherein the independent activation or control is based on absolute time or an elapsed time.

22. The method of claim 21 wherein the absolute time is obtained by of internet connection between the light assembly and a server configured to output absolute time. 23. The method of any one of claims 15 to 22 configured to modulate light output of at least one of the two or more light emitting diodes over a time period, or at a predetermined time.

24. The method of any one of claims 15 to 23 wherein the activation or control is based on an alteration in an electrical parameter of one of the two or more diodes.

25. The method of claim 24 wherein the electrical parameter is selected from the group consisting of voltage, current and resistance. 26. An electronic circuit as substantially described herein with reference to the drawings.