Patent Application
20140313749
The present invention relates to lighting. More specifically, the present invention relates to high efficiency lighting sources.
The era of the Edison vacuum light bulb will be coming to an end soon. In many countries and in many states, common incandescent bulbs are becoming illegal, and more efficient lighting sources are being mandated. Some of the alternative light sources currently include fluorescent tubes, halogen, and light emitting diodes (LEDs). Despite the availability and improved efficiencies of these other options, many people have still been reluctant to switch to these alternative light sources.
The inventors of the present believe that there are several key reasons why consumers have been slow to adopt the newer technologies. One such reason is the use of toxic substances in the lighting sources. As an example, fluorescent lighting sources typically rely upon mercury in a vapor form to produce light. Because the mercury vapor is considered a hazardous material, spent lamps cannot simply be disposed of at the curbside but must be transported to designated hazardous waste disposal sites. Additionally, some fluorescent tube manufacturers go so far as to instruct the consumer to avoid using the bulb in more sensitive areas of the house such as bedrooms, kitchens, and the like.
The inventors of the present invention also believe that another reason for the slow adoption of alternative lighting sources is the low performance compared to the incandescent light bulb. As an example, fluorescent lighting sources often rely upon a separate starter or ballast mechanism to initiate the illumination. Because of this, fluorescent lights sometimes do not turn on “instantaneously” as consumers expect and demand. Further, fluorescent lights typically do not immediately provide light at full brightness, but typically ramp up to full brightness within an amount of time (e.g. 30 seconds). Further, most fluorescent lights are fragile, are not capable of dimming, have ballast transformers that can emit annoying audible noise, and can fail in a shortened period of time if cycled on and off frequently. Because of this, fluorescent lights do not have the performance consumers require.
Another type of alternative lighting source more recently introduced relies on the use of light emitting diodes (LEDs). LEDs have advantages over fluorescent lights including the robustness and reliability inherent in solid state devices, the absence of toxic chemicals that can be released during accidental breakage or disposal, instant-on capabilities, dimmability, and the absence of audible noise. The inventors of the present invention believe, however, that current
LED lighting sources themselves have significant drawbacks that cause consumers to be reluctant to using them.
A key drawback with current LED lighting sources is that the light output (e.g. lumens) is relatively low. Although current LED lighting sources draw a significantly lower amount of power than their incandescent equivalents (e.g. 5-10 watts v. 50 watts), they are believed to be far too dim to be used as primary lighting sources. As an example, a typical 5 watt LED lamp in the MR-16 form factor may provide 200-300 lumens, whereas a typical 50 watt incandescent bulb in the same form factor may provide700-1000 lumens. As a result, current LEDs are often used only for exterior accent lighting, closets, basements, sheds or other small spaces.
Another drawback with current LED lighting sources includes that the upfront cost of the
LED is often shockingly high to consumers. For example, for floodlights, a current 30 watt equivalent LED bulb may retail for over $60, whereas a typical incandescent floodlight may retail for $12. Although the consumer may rationally “make up the difference” over the lifetime of the LED by the LED consuming less power, the inventors believe the significantly higher prices greatly suppress consumer demand. Because of this, current LED lighting sources do not have the price or performance that consumers expect and demand.
Additional drawbacks with current LED lighting sources includes they have many parts and are labor intensive to produce. As merely an example, one manufacturer of an MR-16 LED lighting source utilizes over 14 components (excluding electronic chips), and another manufacturer of an MR-16 LED lighting source utilizes over 60 components. The inventors of the present invention believe that these manufacturing and testing processes are more complicated and more time consuming, compared to manufacturing and testing of a LED device with fewer parts and a more modular manufacturing process.
Additional drawbacks with current LED lighting sources, are that the output performance is limited by heat-sink volume. More specifically, the inventors believe for replacement LED light sources, such as MR-16 light sources, current heat-sinks are incapable of dissipating very much heat generated by the LEDs under natural convection. In many applications, the LED lamps are placed into an enclosure such as a recessed ceiling that already have an ambient air temperatures to over 50 degrees C. At such temperatures the emissivity of surfaces play only a small roll of dissipating the heat. Further, because conventional electronic assembly techniques and LED reliability factors limit PCB board temperatures to about 85 degrees C., the power output of the LEDs is also greatly constrained. At higher temperatures, the inventors have discovered that radiation plays much more important role thus high emissivity for a heat-sink is desirable.
Traditionally, light output from LED lighting sources have been increased by simply increasing the number of LEDs, which has lead to increased device costs, and increased device size. Additionally, such lights have had limited beam angles and limited outputs.
Accordingly, what is desired is a highly efficient lighting source without the drawbacks described above.
The present invention relates to high efficient lighting sources. More specifically, the present invention relates to a novel LED lighting source and methods of manufacturing thereof Some general goals include, to increase light output without increasing device cost or device size, to enable coverage of many beam angles, and to provide a high reliability product for long life (ROI).
Various embodiments of the present invention include a novel modular lighting source.
More specifically, various embodiments include an MR-16 form factor light source. A lighting module includes from 20 to 110 LEDs arrayed in series upon a top surface of thermally conductive substrate (e.g. silicon substrate). The top surface of the silicon substrate is soldered onto a first portion of a flexible printed circuit substrate (FPC). The bottom surface of the conductive silicon substrate is physically bonded to a recess of an MR-16 form factor heat-sink via a thermal epoxy. In various embodiments, electrical driving components are soldered onto a second portion of the FPC, and the second portion of the FPC is inserted into an interior cavity of a thermally conductive plug base. A potting compound is then injected into the cavity of the plug base and to the recess of the heat-sink in one step. The potting compound allows heat generated by the silicon substrate and the electrical driving components to be transferred to the heat-sink or thermally conductive plug base. A lens is then secured to the heat-sink.
In one embodiment, the electrical driving portion/module transforms the input power from 12 AC volts to a higher DC voltage, such as 40 volts 120 Volts. In turn, the driving portion drives the lighting module with the higher voltage, and the lighting module emits the light. The light is conditioned with the lens to the desired type of lighting, e.g. spot, flood, etc. In operation, the driving module and the lighting module produce heat that is dissipated by the MR-16 form factor heat-sink. At steady state, these modules may operate in the range of approximately 75° C. to 130° C.
In various embodiments of the present invention the MR-16 form factor heat-sink greatly facilitates the dissipation of heat. The heat-sink includes an inner core that has a diameter less than half the outer diameter of the heat-sink. In various embodiments, the inner core is less than one third, one fourth, and one fifth the outer diameter. The silicon substrate of the LEDs is directly bonded to the inner core region via the thermal epoxy.
In various embodiments, because the diameter of the inner core is much less than the outer diameter, a larger amount of heat dissipating fins can be provided. A number of heat dissipating fin configurations have been developed and studied by the inventors. Typical fin configurations include a number radiating fin “trunks” extending from the inner core. In some embodiments, the number of trunks range from 8 to 35. At the end of each trunk, two or more fin “branches” are provided having “U” branching shape. In various embodiments, at the end of each branch, two or more fin “sub-branches” are provided, also having a “U” branching shape. In various embodiments, the fin thickness of the trunk may be thicker than the branches, which in turn may be thicker than the sub-branches, etc. The amount of heat flow from the inner core towards the outer diameter, airflow, and surface area are therefore carefully engineered to greatly increase heat dissipating capability.
Other aspects of various embodiments include: simplified construction facilitating high volume manufacturing, flex interconnects to eliminate hand wiring, modular subassembly construction to enable parallel processing. Other features include thermal management aspects: Fin branching algorithm, reduced cross section central core, airflow behind lens, single thermal interface, direct die attachment, flex printed circuits, base contour to minimize potting material, recessed front, ensured airflow with coverage; Low-Cost Manufacturing: flexible printed circuit interconnect (Main and interposer), flex circuit light chip interposer, redundant latching and bonding features, and the like. Other aspects include: high temperature operation enabling a densely packed LED array, higher component reliability, high heat dissipation, maximum surface area, maximum airflow, minimum thermal interface losses, minimum length thermal paths within the electronics module, and the like. Advantages with embodiments of the present invention include operating a LED light source reliably at high temperatures, allowing the concentration of a large number of LEDs in a small space while simultaneously operating them at higher power levels.
According to one aspect of the invention, a light source is described. One apparatus includes a heat-sink comprising a mounting region, and a plurality of heat-dissipating fins, and a base housing coupled to the heat-sink, wherein the base housing includes an inner cavity. A device may include an integrated lighting module coupled to the heat-sink and to the base housing. The integrated lighting module may include a printed circuit board, a light emitting source formed on a top surface of substrate, wherein the top surface of the substrate is coupled to a first surface of the printed circuit board within a first lateral region of the printed circuit board, and an electronic driving circuit configured to provide electrical power to the light emitting source, wherein the electronic driving circuit is coupled to the first surface of the printed circuit board within a second lateral region of the printed circuit board. In various apparatus a bottom surface of the substrate is thermally coupled to the mounting region of the heat-sink, and wherein the second lateral region of the integrated lighting module is located within the inner cavity of the base housing.
According to yet another aspect of the invention, a method for assembling a light source is described. One technique includes receiving a heat-sink comprising a mounting region, and a plurality of heat-dissipating structures, and receiving a base housing coupled to the heat-sink, wherein the base housing includes an inner cavity. A process may include receiving an integrated lighting module, wherein the integrated lighting module includes a printed circuit board having a first lateral region and a second lateral region, wherein a first surface of the printed circuit board within the first lateral region is coupled to a top surface of a light emitting source substrate, and wherein the first surface of the printed circuit board within the second lateral region is coupled to a plurality of electronic driving devices. A methodology may include disposing the second lateral region of the integrated lighting module within the inner cavity of the base housing, and coupling a bottom surface of the light emitting source substrate to the mounting region of the heat-sink.
In order to more fully understand the present invention, reference is made to the accompanying drawings. Understanding that these drawings are not to be considered limitations in the scope of the invention, the presently described embodiments and the presently understood best mode of the invention are described with additional detail through use of the accompanying drawings in which:
In various embodiments, an LED assembly described in the pending patent applications described above, and variations thereof, may be used within LED lighting source 100. Theses LED assemblies are currently under development by the assignee of the present patent application. In various embodiments, LED lighting source 100 may provide a peak output brightness of approximately 7600 to 8600 candelas (with approximately 360 to 400 lumens), a peak output brightness of approximately 1050 to 1400 candelas for a 40 degree flood light (with approximately 510 to 650 lumens), and a peak output of approximately 2300 to 2500 candelas for a 25 degree flood light (with approximately 620 to 670 lumens), and the like. Various embodiments of the present invention therefore are believed to have achieve the same brightness as conventional halogen bulb MR-16 lights.
In various embodiments, lens 210 may be formed from a UV and resistant transparent material, such as glass, polycarbonate material, or the like. In various embodiments, lens 210 may be solid. In the case of lens 210, the solid material creates a folded light path such that light that is generated by the integrated LED assembly 220 internally reflects within lens 210 more than one time prior to being output. Such a folded optic lens enables light 200 to have a tighter columniation of light than is normally available from a conventional reflector of equivalent depth.
In various embodiments, to increase durability of the lights, the transparent material should be operable at an elevated temperature (e.g. 120 degrees C.) for a prolonged period of time (e.g. hours). One material that may be used for lens 210 is known as Makrolon™ LED 2045 or LED 2245 polycarbonate available from Bayer Material Science AG. In other embodiments, other similar materials may also be used.
In
In various embodiments of the present invention, LED assemblies may be binned based upon lumen per watt efficacy. For example, in some examples, an integrated LED module/assembly having a lumen per watt (L/W) efficacy from 53 to 66 L/W may be binned for use for 40 degree flood lights, a LED assembly having an efficacy of approximately 60 L/W may be binned for use for spot lights, a LED assembly having an efficacy of approximately 63 to 67 L/W may be use for 25 degree flood lights, and the like. In other embodiments, other classification or categorization of LED assemblies on the basis of L/W efficacy may used for other target applications.
In some embodiments, as will be discussed below integrated LED assembly/module 220 typically includes 36 LEDs arranged in series, in parallel series (e.g. three parallel strings of 12 LEDs in series), or the like. In other embodiments, any number of LEDs may be used, e.g. 1, 10, 16, or the like. In other embodiments, the LEDs may be electrically coupled in other manner, e.g. all series, or the like. Further detail regarding such LED assemblies are provided in the patent applications incorporated by reference above.
In various embodiments, the targeted power consumption for LED assemblies is less than 13 watts. This is much less than the typical power consumption of halogen based MR-16 lights (50 watts). Accordingly, embodiments of the present invention are able to match the brightness or intensity of halogen based MR-16 lights, but using less than 20% of the energy.
In various embodiments of the present invention, LED assembly 220 is directly secured to heat-sink 230. As will be discussed below, LED assembly 220 typically includes a flat substrate such as silicon or the like. In various embodiments, it is contemplated that an operating temperature of LED assembly 220 may be on the order of 125 to 140 degrees C. The silicon substrate is then secured to the heat-sink using a high thermal conductivity epoxy (e.g. thermal conductivity ˜96 W/m.k.). In some embodiments, a thermoplastic/thermo set epoxy may be used such as TS-369, TS-3332-LD, or the like, available from Tanaka Kikinzoku Kogyo K.K. Other epoxies may also be used. In some embodiments, no screws are otherwise used to secure the LED assembly to the heat-sink, however, screws or other fastening means may also be used in other embodiments.
In various embodiments, heat-sink 230 may be formed from a material having a low thermal resistance/high thermal conductivity. In some embodiments, heat-sink 230 may be formed from an anodized 6061-T6 aluminum alloy having a thermal conductivity k=167 W/m.k., and a thermal emissivity e=0.7. In other embodiments, other materials may be used such as 6063-T6 or 1050 aluminum alloy having a thermal conductivity k=225 W/mk and a thermal emissivity e=0.9. In other embodiments, still other alloys such AL 1100, or the like may be used. Additional coatings may also be added to increase thermal emissivity, for example, paint provided by ZYP Coatings, Inc. utilizing CR2O3 or CeO2 may provide a thermal emissivity e=0.9; coatings provided by Materials Technologies Corporation under the brand name Duracon™ may provide a thermal emissivity e>0.98; and the like. In other embodiments, heat-sink 230 may include other metals such as copper, or the like.
In some example, at an ambient temperature of 50 degrees C., and in free natural convection heat-sink 230 has been measured to have a thermal resistance of approximately 8.5 degrees C./Watt, and heat-sink 290 has been measured to have a thermal resistance of approximately 7.5 degrees C./Watt. With further development and testing, it is believed that a thermal resistance of as little as 6.6 degrees C./Watt are achievable in other embodiments. In light of the present patent disclosure, it is believed that one of ordinary skill in the art will be able to envision other materials having different properties within embodiments of the present invention.
In various embodiments, base assemblies/modules 240 in
The shell of base assembly 240 may be formed from an aluminum alloy, and may formed from an alloy similar to that used for heat-sink 230 and/or heat-sink 290. In one example, an alloy such as AL 1100 may be used. In other embodiments, high temperature plastic material may be used. In some embodiments of the present invention, instead of being separate units, base assembly 240 may be monolithically formed with heat-sink 230.
As illustrated in
In various embodiments, to facilitate a transfer of heat from the LED driving circuitry to the shell of the base assemblies, and of heat from the silicon substrate of the LED device, a potting compound is provided. The potting compound may be applied in a single step to the internal cavity of base assembly 240 and to the recess within heat-sink 230. In various embodiments, a compliant potting compound such as Omegabond® 200 available from Omega Engineering, Inc. or 50-1225 from Epoxies, Etc. may be used. In other embodiments, other types of heat transfer materials may be used.
In various embodiments, the LEDs 300 are mounted upon a silicon substrate 310, or other thermally conductive substrate. In various embodiments, a thin electrically insulating layer and/or a reflective layer may separate LEDs 300 and the silicon substrate 310. Heat produced from LEDs 300 is typically transferred to silicon substrate 310 and to a heat-sink via a thermally conductive epoxy, as discussed above.
In various embodiments, silicon substrate is approximately 5.7 mm×5.7 mm in size, and approximately 0.6 microns in depth. The dimensions may vary according to specific lighting requirement. For example, for lower brightness intensity, fewer LEDs may be mounted upon the substrate, accordingly the substrate may decrease in size. In other embodiments, other substrate materials may be used and other shapes and sizes may also be used
As shown in
As illustrated in
Illustrated in
Various shapes and sizes for FPC 340 are contemplated in various embodiments of the present invention. For example, as illustrated in
In various embodiments, the silicon substrate 310 is bonded to a first portion of FPC 340. As shown in
In
After the electronic driving devices and the silicon substrate 310 are bonded to FPC 340, the LED package sub assembly or module 220 is thus assembled. In various embodiments, these LED modules may then be individually tested for proper operation.
In various embodiments, the following process may be performed to form an LED assembly/module. Initially, a plurality of LEDs 300 are provided upon an electrically insulated silicon substrate 310 and wired, step 400. As illustrated in
Next, a plurality of electronic driving circuit devices and contacts may be soldered to the flexible printed circuit 340, step 430. The contacts are for receiving a driving voltage of approximately 12 VAC. As discussed above, unlike present state of the art MR-16 light bulbs, the electronic circuit devices, in various embodiments, are capable of sustained high-temperature operation, e.g. 120 degrees C.
In various embodiments, the second portion of the flexible printed circuit including the electronic driving circuit is inserted into the heat-sink and into the inner cavity of the base module, step 440. As illustrated, the first portion of the flexible printed circuit is then bent approximately 90 degrees such that the silicon substrate is adjacent to the recess of the heat-sink. The back side of the silicon substrate is then bonded to the heat-sink within the recess of the heat-sink using an epoxy, or the like, step 450. Subsequently a potting material is used to fill the air space within the base module and to serve as an under fill compound for the silicon substrate, step 460.
Subsequently, a lens may be secured to the heat-sink, step 470, and the LED light source may then be tested for proper operation, step 480.
In
In various embodiments, lighting source 600 represents a configuration of an LED light source having a combination of performance characteristics that have not been previously achievable with LED light sources. More specifically, in a spot light configuration, as shown in
In the cross-section in
Further embodiments can be envisioned to one of ordinary skill in the art after reading this disclosure. In other embodiments, combinations or sub-combinations of the above disclosed invention can be advantageously made. The block diagrams of the architecture and flow charts are grouped for ease of understanding. However it should be understood that combinations of blocks, additions of new blocks, re-arrangement of blocks, and the like are contemplated in alternative embodiments of the present invention.
The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope.
The present application relates to and claims priority to U.S. Provisional Patent Application No. 61/391,506, filed Oct. 8, 2010. This provisional patent application is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 61391506 | Oct 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13269193 | Oct 2011 | US |
| Child | 14320076 | US |
