Patent Publication Number: US-2011050101-A1

Title: Controllable Lighting System

Description:
PRIORITY DATA 
     This application claims benefit of priority to U.S. Provisional Patent Application No. 61/275,401 titled “Lighting Device, Features, And Manufacturing Methods,” filed on Aug. 28, 2009, whose inventors were Stephen Barcik, Bill Kernion, and Brad Bailey which is hereby incorporated by reference in its entirety as though fully and completely set forth herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to lighting, and more particularly, to a solid state lighting replacement for lighting devices or systems and its operation. 
     DESCRIPTION OF THE RELATED ART 
     U.S. and international regulations call for phasing out existing lighting solutions, such as incandescent light bulbs, fluorescent lamps, and electrical ballasts. As a result, the light emitting diode (LED) and solid state lighting industry is growing rapidly. Industry and end users are calling for LEDs to be replacements for traditional lighting systems, such as those associated with traffic control signals and automobile brake lights, among others. The replacement of conventional incandescent light bulbs with one or more LEDs is desirable because incandescent bulbs are inefficient relative to LEDs in terms of energy efficiency, heat management, and longevity. 
     The LED is a lighting device made of semiconductor p-n junction diodes. A LED generally includes a diode fabricated onto a semiconductor die which receives electrical power from a power source and supplies power to the diode. To produce a brighter LED, generally more power is delivered to the LED. Modules composed of many LEDs are used in many applications such as flat screen displays and other devices to provide illumination. LEDs have been used for decades in applications requiring relatively low-energy indicator lamps, numerical readouts, and the like. LED modules were originally produced for use as direct substitutes for standard LED lamps. However, due to their unique shape, size, and power consumption requirements, they present manufacturing and assembly difficulties that were originally unanticipated by LED manufacturers, resulting in generally bulky and non-serviceable components. Additionally, removal and replacement of LEDs in an LED module is often costly, cumbersome, impossible, and/or time consuming. Despite the prevalence of their use, LEDs and LED modules have well known disadvantages and limitations. 
     Prior art solutions exhibit significant shortcomings from a performance and price point standpoint. Complexities of heat removal from LED packages and overall thermal management difficulties result in manufacturers de-rating the luminous output of lamps to minimize heat loading. The result is reduced lumens output compared to the equivalent incandescent lamp. Some manufacturers attempt to solve the thermal management problem with complex and costly cast heat sink designs. This approach greatly increases design and manufacturing cost and drives the lamp cost to a non-competitive price point. Also, serious heat transfer or conduction problem arise when a plurality of densely packaged chips are used. 
     Currently known lighting systems have failed to assemble multiple LEDs in a compact fashion while maintaining the necessary heat transfer characteristics. Also, LED lighting systems dissipate heat by a different heat transfer path than ordinary filament bulb systems; more specifically, these higher power LED lighting systems dissipate a substantial amount of heat via a cathode (negative terminal) leg or through a die attached to a thermal slug in a direct die mount device. Consequently, the higher power LED systems tend to run at higher temperatures. Higher operation temperatures degrade the performance of the higher power LED lighting systems. Additionally, LED modules for use in a display or an illumination device have many LEDs, and most of the LEDs are driven at the same time, which results in a quick rise in temperature of the LED module. Consequently light output quality from the LED module is degraded with illumination and shows undesirable color shift, flicker, and reduced intensity. A substantial technical challenge to producing a reliable device based on LED light sources lies in packaging the light sources such that effective thermal management is realized. Excessive operating temperature of the light sources often results in premature failure. 
     Prior art solutions also exhibit significant shortcomings from the standpoint of upgradeablity, replaceablity, serviceablity, and modularity. In many typical mounting arrangements, LEDs are mounted in a mounting assembly or mount which is then soldered to a printed circuit board using surface mount assembly techniques. In such arrangements, to remove and replace a defective or burned out LED, to change out one LED or another, or to upgrade to an improved LED technology, it is necessary to heat the solder holding the original LED mount in place to its melting point and then to remove the original LED mount, clean the board, and then to resolder a replacement LED mount in its place. Alternatively, a whole new replacement board may be utilized to avoid the step of replacing the LED completely. Both of these approaches have their drawbacks with respect to ease of replacements, cost, efficiency, or the like. 
     Prior art solutions also exhibit significant shortcomings from the standpoint of cost and difficulty of manufacturing a heat sink for use in a LED illumination module. A major shortcoming of prior art heat sink design is that they are generally difficult to manufacture. Such heat sinks require enormously high production cycle time and tooling costs to manufacturer which, of course, makes them cost ineffective. The manufacturing techniques for heat sinks implemented in LED modules are die casting, die forging, precision sawing, electrical discharge machining, and numerically controlled machining In some prior art solutions, a method of manufacturing a pin-finned heat sink from an extrusion is limited by what is obtainable by an extrusion process. Additionally, many manufacturers offer bonded fin heat sinks assemblies in which each fin in the assembly is individually bonded into a heat sink base. A major shortcoming of such heat sinks is their high cost. This cost is related directly to the labor required to individually arrange each fin on some sort of support or substrate and high production cycle time. 
     Prior art solutions also exhibit significant shortcomings from the standpoint of beam conditioning associated with lens and light-emitting assemblies for use in a LED illumination module. In many applications involving the use of semiconductor LEDs, it is desirable to condition the optical output of a light-emitting source to suit various objectives. In other applications, it is desirable to mix optical outputs from a plurality of light-emitting sources, such as LEDs of the three primary colors of red, green, and blue. The mixing of light from a plurality of LEDs, for example, LEDs emitting the three primary colors, is advantageous, since by separating the LEDs into a plurality of distributed locations and then by mixing light from a plurality of distributed sources, problems associated with a the high power dissipation and the consequential thermal loading of a high power discrete white LED can be alleviated. However, typical distribution characteristics of a typical LED means that a relatively large distance is generally be required for light mixing. Therefore, would be desirable to provide optical arrangements and beam conditioning for reducing the light mixing distance between a plurality of LEDs. 
     Prior art solutions also exhibit significant shortcomings from the standpoint of lack of intelligent control of a network of LED illumination modules. Existing lighting systems are limited in the sense that they have generally involved light sources coupled to a source of power via manually operated mechanical switches. The result is lack of automation control and intelligent control of various lighting scenarios. Furthermore, a network of lighting modules is highly inefficient in terms of intensity per unit of power consumed. Additionally, such a network of lighting devices is unable to effectively and efficiently produce desired hue and color variations. A significant problem with present lighting networks is that they require special wiring or cabling. In particular, one set of wires is needed for electrical power, while a second set of wires is needed for data, such as for protocol data. Another significant problem with present lighting network is that particular lighting applications require particular lighting types. For example, LED based lights are appropriate for some applications, while incandescent lights or halogen lamps may be more appropriate for other applications. A user who wishes to have a digitally controlled network of lights, in addition to rewiring, must currently add additional fixtures or replace old fixtures for each different type of light. 
     Accordingly, improved systems and methods for lighting are needed. 
     SUMMARY OF THE INVENTION 
     Described herein are embodiments of a lighting system and various methods of operation. Embodiments of the invention may, but are not required to, address one or more of the shortcomings described above. 
     In one embodiment, the lighting system (also referred to as a thermal management lighting system) comprises a replaceable illumination module and a base module. The replaceable illumination module may be removably coupled to the base module. The replaceable illumination module may include one or more solid state lighting elements and a printed circuit board that is electrically and thermally connected to the solid state lighting elements. The solid state lighting elements may be various types, such as one or more of a direct current light emitting diode, an alternating current light emitting diode, a multicolor light emitting diode, a solid state light source, an organic light emitting diode, or a flexible-circuit light emitting diode. The printed circuit board may comprise or be connected to a thermal spreading element. The thermal spreading element has an interface surface for thermally coupling to a heat sink. 
     The base module may comprise a heat sink that may be in thermal contact with the replaceable illumination module via the thermal spreading element. For example, the thermal spreading element may be held in thermal contact with the heat sink via a fastening means that maintains a specified interfacial force between the thermal spreading element and the heat sink. A flow baffle may encircle the heat sink and utilize a temperature differential to promote convective heat transfer away from the heat sink. The heat sink may operate to dissipate heat generated by the one or more solid state lighting elements during operation. 
     A cover cap may be affixed to the printed circuit board to protect the solid state lighting elements and the circuit board from environmental intrusions. The cover cap may also diffuse light from the solid state lighting elements. At least a portion of the cover cap may be made of a smart material to block moisture and also support convective heat transfer. The smart material may comprise, e.g., a thermally conductive material with thermal conductivity of at least approximately 0.9 W/m-K and/or a porous material with a pore density of at least approximately 10 7  pores/cm 2 . 
     In one embodiment, the heat sink comprises at least one extrusion having a plurality of heat fins. The extrusion may be tapered. Each heat fin may have a specified nonzero curvature, and the plurality of heat fins form a plurality of air flow channels for convectively dissipating heat. The plurality of heat fins are preferably made of a material with a thermal conductivity of at least approximately 180 W/m-K. The heat sink may comprise a plurality of stacked extrusions, where each stacked extrusion has a respective radius. The plurality of stacked extrusions may be ordered in accordance with their respective radii to form a stepwise tapered heat sink. In one embodiment, the heat fins of at least one of the stacked extrusion are not aligned with corresponding heat fins of at least one adjacent stacked extrusion. 
     The lighting system may also comprise a base connector mechanically coupled to but electrically isolated from the heat sink, wherein the base connector is configured to receive power from a lighting socket during operation. The lighting system may further comprise a driver circuit coupled to or comprised in the printed circuit board or the base module. The driver circuit may be configured to receive power from the base connector and provide the power to the solid state lighting elements via the printed circuit board. The driver circuit may comprise a DC driver circuit to convert and modulate AC line voltage for operation of the solid state lighting elements. The DC driver circuit may scale current output or voltage output according to AC input voltage. Also, the DC driver circuit may convert the incoming AC power to provide intensity control via pulse width modulation (PWM). The PWM may be scaled by a function of AC input voltage or alternate control input. In one embodiment, the driver circuit is an AC driver circuit which comprises a diode rectifier to directly drive the one or more solid state lighting elements. Each of the solid state lighting elements may comprise a single or multiple junction solid state lighting element, comprising one or more AC solid state lighting elements and/or one or more DC solid state lighting elements. 
     The lighting system may also comprise a wavelength sensor component for modulating color temperature output from the replaceable illumination module. The wavelength sensor component may be comprised in or electrically coupled to the replaceable illumination module. The lighting system may also or instead comprise an intensity sensor component that is comprised in or electrically coupled to the replaceable illumination module. The intensity sensor component may be configured to modulate light intensity output from the replaceable illumination module. 
     The lighting system may further comprise an active cooling element coupled to or comprised in the replaceable illumination module. The active cooling element may comprise one or more of a thermoelectric cooler, a phase-change device, a fan, a piezoelectric fan, a voice coil based flipper fan, a synthetic jet cooler, or an acoustically-driven cooler. The lighting system may also, or instead, comprise a passive cooling element coupled to or comprised in the replaceable illumination module. The passive cooling element comprises one or more of a heat pipe, a Venturi effect device, or a convective flow device. 
     The lighting system may comprise at least one sensor comprised in or coupled to the replaceable illumination module or the heat sink. The sensor may comprise, e.g., a photosensor, a color sensor, a light-intensity sensor, or a temperature sensor. The sensor may be configured to couple to an automated control network for regulation of color output, light-intensity output, or temperature in the replaceable illumination module by the automated control network. The sensor may also wirelessly couple to the automated control network. For example, the sensor may be a temperature sensor configured for use in sensing, feedback, and control of temperature in the replaceable illumination module. As another example, the sensor may be a wavelength sensor component for sensing and modulating color temperature output of the replaceable illumination module. As another example, the sensor may be an intensity sensor component for sensing and modulating light intensity output of the replaceable illumination module. 
     Embodiments of a method for use of a replaceable illumination module are also presented. The method may include providing a lighting device that includes a first replaceable illumination module and a base module as described above. When replacement is desired, the first replaceable illumination module may be removed (or detached) from the base module, and a second replaceable illumination module is installed (or attached) to the base module of the lighting device. After installation of the second replaceable illumination module, the lighting device provides illumination using the second replacement illumination module. Where the lighting device is inserted into a lighting socket, the lighting device may first be removed the socket before the replacement described above, and then may be re-inserted after replacement. Alternatively, the lighting device may remain inserted in the socket during the replacement. 
     In one embodiment, the replaceable illumination module also comprises one or more beam conditioning optical elements proximate to the one or more solid state lighting elements. The beam conditioning optical elements may be configured to modify light output from the solid state lighting elements to produce a specified beam. For example, the beam conditioning optical elements may be configured to control color temperature during operation of the replaceable illumination module. 
     In one exemplary method of operation, power is received to an electrical connector of the replaceable illumination module from an external power source and is provided to a printed circuit board of the replaceable illumination module via the connector. Power is then provided via the printed circuit board to the one or more solid state lighting elements. The solid state lighting elements emit light and also produce heat. The one or more beam conditioning optical elements transform at least a portion of the emitted light from the solid state lighting elements, e.g. by controlling color temperature. Also, the thermal spreading element conducts heat from the solid state lighting elements to the heat sink via the interface surface. 
     In one embodiment, at least one of the beam conditioning optical elements is configured to spectrally transform light from the one or more solid state lighting elements by absorbing photons with a first spectral distribution and emitting photons with a second spectral distribution. In this embodiment, the beam conditioning optical element may comprise one or more of a phosphor material, a nanophotonic material, a crystalline photonic material, an optical fiber material, a photonic crystal fiber material, an engineered microstructure material, or a dielectric waveguide material. 
     The one or more beam conditioning optical elements may comprise one or more beam forming elements that are configured to modify a spatial intensity distribution of the photons of the second spectral distribution for control of beam concentration and beam divergence. In this embodiment, the beam forming elements may comprise at least one of one or more reflective optical elements, one or more diffractive optical elements, or one or more refractive elements. Further, the beam forming elements may comprise one or more prism structures or one or more Fresnel lenses. The one or more refractive elements may comprise one or more lenses and/or one or more micro-lens arrays. 
     In one embodiment, as noted above, the lighting system comprises one or more sensors proximate to the one or more beam conditioning optical elements, and control circuitry coupled to the one or more sensors. The sensors may be a photosensor, a color sensor, and/or a light-intensity sensor. The control circuitry is configured to monitor spectral distribution or intensity distribution of spectrally transformed light from the one or more solid state lighting elements via the one or more sensors and modify at least one of the beam conditioning optical elements to control color temperature or intensity distribution of the beam. The control circuitry may be configured to couple to an automated control network (e.g., wirelessly) for regulation of color output or light-intensity output of the lighting system by the automated control network. 
     In one embodiment, at least two of the solid state lighting elements each comprises a respective specified spectral output, and at least one of the beam conditioning optical elements is configured to homogenize light output from the plurality of solid state lighting elements. 
     In one exemplary method of operation, power is received by the replaceable illumination module and provided via the printed circuit board to the one or more solid state lighting elements. The solid state lighting elements emit light and also produce heat. At least one of the beam conditioning optical elements spectrally transforms light from the one or more solid state lighting elements, e.g., by absorbing photons with a first spectral distribution and emitting photons with a second spectral distribution. In this embodiment, at least one beam conditioning optical element may comprise one or more of the materials or configurations mentioned above. Also, as noted above, the beam conditioning optical elements may comprise one or more beam forming elements that operate to modify a spatial intensity distribution of the photons of the second spectral distribution for control of beam concentration and beam divergence. Also, as noted above, the replacement illumination module may comprise a thermal spreading element that conducts heat from the solid state lighting elements to the heat sink via the interface surface. 
     In one embodiment, the replaceable illumination module is included in a controllable lighting system that comprises one or more sensors and control circuitry. The one or more sensors are coupled to or comprised in the replaceable illumination module and are configured to measure one or more attributes of the replaceable illumination module or its environment. For example, the sensors may be a light sensor, temperature sensor, pressure sensor, motion sensor, a smoke detector, a chemical sensor, or a carbon monoxide detector, etc. The control circuitry is coupled to or comprised in the replaceable illumination module and is configured to monitor the attributes to determine a status of the controllable lighting system via the one or more sensors. The control circuitry (or other control logic) uses the attributes and/or the determined status to regulate the controllable lighting system or control a system coupled to the controllable lighting system. 
     The one or more sensors may comprise a temperature sensor configured to measure temperature of the replaceable illumination module. The control circuitry may be configured to monitor the temperature via the temperature sensor and control the controllable lighting system to regulate the temperature. The control circuitry may regulate the temperature by deactivating or activating at least one of the solid state lighting elements or modifying power provided to the printed circuit board. The control circuitry may also regulate temperature by activating or deactivating at least one active cooling element, which may be any of various types as described above. 
     In one embodiment, as noted above, the controllable lighting system further comprises one or more beam conditioning optical elements proximate to the one or more solid state lighting elements. The beam conditioning optical elements may be configured in various manners as described above. The beam conditioning optical elements are configured to modify light output from the solid state lighting elements. A light sensor is coupled to detect the light output. The control circuitry is configured to monitor light emitted from the solid state lighting elements or ambient light via the light sensor and control the beam conditioning optical elements to generate a specified beam. As noted above, at least one of the beam conditioning optical elements is configured to spectrally transform light from the solid state lighting elements by absorbing photons with a first spectral distribution and emitting photons with a second spectral distribution. The beam conditioning optical elements may also be configured to modify a spatial intensity distribution of the beam. 
     In one embodiment, the controllable lighting system is comprised in a multi-zoned lighting system, and network control of the controllable lighting system comprises occupancy dependent zone control. In another embodiment, the controllable lighting system is comprised in or coupled to an alarm or notification system. For example, the system may comprise one or more of a video camera, a still camera, a motion sensor, a smoke detector, a chemical sensor, or a carbon monoxide detector. 
     Embodiments of the invention may also comprise a method for operating a lighting system as described above. The method may include the sensors detecting various attributes of the replaceable illumination module or its environment. The control circuitry monitors these attributes to determine a status of the controllable lighting system. The control circuitry then regulates the controllable lighting system or controls a system coupled to the controllable lighting system based on the determined status. 
     The controllable lighting system may be coupled to an automated control network, and operation of the lighting system may comprise sending the determined status to a controller of the automated control network and receiving control signals from the controller of the automated control network. Regulation of the lighting system may then be performed in response to the control signals. 
     The heat sink described herein may be constructed using any of various techniques. One embodiment of the invention includes a method for manufacturing a work piece, such as the heat sink described above. The method may comprise providing an extrusion die that is controllable to dynamically vary one or more cross sectional attributes of the work piece. The method may then comprise extruding a material via the extrusion die to generate the work piece. The extrusion process may comprise dynamically controlling the extrusion die to vary at least one cross sectional attribute of the work piece during the extruding. For example, dynamically controlling the extrusion die may comprise rotating the extrusion die to impart a twist to the work piece, heating the extrusion die, and/or varying a cross section of the extrusion die to taper the work piece. The extrusion process may also comprise thermally modifying the material. The generated work piece may have a variable longitudinal profile in accordance with the dynamically controlling performed during the extrusion process. 
     The method for manufacturing the work piece may comprise applying a braising paste or a furnace bake to the generated work piece. Also, after performing the extrusion process, the construction method may comprise thermally heating the work piece, compressing the work piece into a mold or a forming structure, or rotating the work piece into a mold or a forming structure. The forming structure may be fixed or articulated. Compression of the work piece may comprise forming one or more tapers or notches. 
     As noted above, in one embodiment the work piece is a heat sink that comprises at least one extrusion having a plurality of heat fins. The at least one extrusion may be tapered. Also, each heat fin may comprise a specified nonzero curvature. As noted above, the plurality of heat fins may be made of a material with a thermal conductivity of at least approximately 180 W/m-K. Also, the plurality of heat fins may be made to form a plurality of air flow channels for convectively dissipating heat to the surroundings. In one embodiment, as also noted above, the heat sink is constructed with a plurality of stacked extrusions, wherein each stacked extrusion has a respective radius. The plurality of stacked extrusions may be ordered in accordance with their respective radii to form a stepwise tapered heat sink. For at least one of the stacked extrusions, the heat fins of a first extrusion are not aligned with corresponding heat fins of at least one adjacent stacked extrusion. The method of constructing the heat sink may comprise utilizing a forming wheel to modify each of the plurality of heat fins. 
     An apparatus for constructing a work piece as described above may comprise a dynamically controllable extrusion die system having a controller and an extrusion die coupled to the controller. The controller is configured to dynamically control the extrusion die to generate the work piece. In other words, the controller may generate control signals that are provided to the extrusion die. The controller may dynamically control the extrusion die as described above, e.g., by varying at least one cross sectional attribute of the work piece, rotating the extrusion die to impart a twist to the work piece, heating the extrusion die, and/or varying a cross section of the extrusion die to taper the work piece. The extrusion process may also comprise thermally modifying the material. The generated work piece may have a variable longitudinal profile in accordance with the dynamically controlling performed during the extrusion process. Embodiments of the invention may also comprise a non-transitory memory medium that stores program instructions executable by a controller to dynamically control an extrusion die to extrude a material to generate a work piece as described herein. 
     These and other advantages of the disclosed subject matter, as well as additional novel features, will be apparent from the description provided herein. Various systems, methods, features and advantages here provided will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: 
         FIG. 1  illustrates a lighting system, according to one embodiment; 
         FIG. 2  illustrates one embodiment of a replaceable illumination module with an interface connection; 
         FIG. 3  illustrates a functional decomposition of a replaceable illumination module with interface connection, according to one embodiment; 
         FIG. 4  depicts conductive piers in a replaceable illumination module interface, according to one embodiment; 
         FIGS. 5 and 6  illustrate exemplary embodiments of a shaft and base connector assembly for coupling to a replaceable illumination module; 
         FIG. 7  shows an embodiment of a lighting system module with an exemplary heat sink; 
         FIG. 8  illustrates a heat sink, according to one embodiment; 
         FIG. 9  displays an embodiment of a tapered extrusion formed by a dynamically controllable extrusion; 
         FIG. 10  illustrates an embodiment of a heat sink formed by tapering and twisting an extrusion, according to one embodiment; 
         FIG. 11  shows an exemplary lighting fixture in relation to a lighting system, according to one embodiment; 
         FIG. 12  illustrates convective cooling enhancements to a replaceable illumination module of the present technique, according to one embodiment; 
         FIG. 13  shows convective enhancements to a replaceable illumination module in relation to an exemplary lighting fixture, according to one embodiment; 
         FIG. 14  illustrates an exemplary piezoelectric device for use in a replaceable illumination module, according to one embodiment; 
         FIG. 15  shows an exemplary tube axial fan for use in a replaceable illumination module, according to one embodiment; 
         FIG. 16  depicts an exemplary flexible illumination module, according to one embodiment; 
         FIG. 17  portrays an Edison configuration in a replaceable illumination module, according to one embodiment; 
         FIG. 18  shows a series and parallel combination replaceable chain, according to one embodiment; 
         FIG. 19  illustrates bridge rectification, according to one embodiment; 
         FIG. 20  illustrates an automated control system for lighting control, according to one embodiment; 
         FIG. 21  depicts exemplary motion sensing in conjunction with an automated control system, according to one embodiment; 
         FIG. 22  illustrates a smart light for use with an automated control system, according to one embodiment; 
         FIG. 23  illustrates a method for use of the lighting system, according to one embodiment; 
         FIG. 24  illustrates a method for operation of a replaceable illumination module, according to one embodiment; 
         FIG. 25  illustrates a method for manufacturing a work piece via a dynamically controllable extrusion die, according to one embodiment; 
         FIG. 26  illustrates a method for beam conditioning in the lighting system, according to one embodiment; and 
         FIG. 27  illustrates a method for operating a controllable lighting system, according to one embodiment. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Incorporation by Reference 
     The following references are hereby incorporated by reference in their entirety as though fully and completely set forth herein: 
     U.S. Provisional Patent Application No. 61/275,401 titled “Lighting Device, Features, And Manufacturing Methods,” filed on Aug. 28, 2009. 
     Terms 
     The following is a glossary of terms used in the present application: 
     Memory Medium—Any of various types of memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a CD-ROM, floppy disks  104 , or tape device; a computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g., a hard drive, or optical storage; registers, or other similar types of memory elements, etc. The memory medium may comprise other types of memory as well or combinations thereof. In addition, the memory medium may be located in a first computer in which the programs are executed, or may be located in a second different computer which connects to the first computer over a network, such as the Internet. In the latter instance, the second computer may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums which may reside in different locations, e.g., in different computers that are connected over a network. 
     Software Program—the term “software program” is intended to have the full breadth of its ordinary meaning, and includes any type of program instructions, code, script and/or data, or combinations thereof, that may be stored in a memory medium and executed by a processor. Exemplary software programs include programs written in text-based programming languages, such as C, C++, PASCAL, FORTRAN, COBOL, JAVA, assembly language, etc.; graphical programs (programs written in graphical programming languages); assembly language programs; programs that have been compiled to machine language; scripts; and other types of executable software. A software program may comprise two or more software programs that interoperate in some manner. Note that various embodiments described herein may be implemented by a computer or software program. A software program may be stored as program instructions on a memory medium. 
     Program—the term “program” is intended to have the full breadth of its ordinary meaning The term “program” includes 1) a software program which may be stored in a memory and is executable by a processor or 2) a hardware configuration program useable for configuring a programmable hardware element. 
     Computer System—any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network appliance, Internet appliance, personal digital assistant (PDA), television system, grid computing system, or other device or combinations of devices. In general, the term “computer system” can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium. 
     LED—any of various types of semiconductor light emitting diodes (LEDs) and organic light emitting diodes (OLEDs). In general, semiconductor dies that produce light in response to current, light emitting polymers, electro-luminescent strips (EL), etc. Furthermore, the use of “LED” may refer to a single light-emitting device having multiple semiconductor dies that are individually controlled. It should also be understood that the use of “LED” does not restrict the package type of an LED. The use of “LED” may refer to packaged LEDs, non-packaged LEDs, surface mount LEDs, chip-on-board (COB) LEDs, and LEDs of all other configurations. The use of “LED” also includes LEDs packaged or associated with phosphor, wherein the phosphor may convert radiant energy emitted from the LED to a different wavelength of light. The use of “LED” will also include high-brightness white LEDs as well as high-brightness color LEDs in different packages. An LED array can include at least one LED or a plurality of LEDs. 
     Solid State Lighting Element—any of various types of light emitting component where photon emission occurs via electroluminescence, typically in a semiconducting material. 
     In the following description, numerous specific details are set forth to enable a thorough understanding of embodiments of the present invention. In some instances, well-known structures and techniques have not been shown in detail to avoid obscuring the present subject matter. 
     Lighting System 
     The following describes various embodiments of a lighting system that includes a replaceable illumination module and a base module. Embodiments of a method for use of a replaceable illumination module are also presented. 
       FIG. 1  illustrates an exemplary embodiment of such a lighting system  100 , including replaceable illumination module  10  and base module  15 . As may be seen, the replaceable illumination module  10  may include one or more solid state lighting elements  14  connected to a printed circuit board  18 , at least one beam conditioning element or component  12 , and a thermal spreading element  16 . The thermal spreading element  16  may be coupled to or included in the printed circuit board  18  and is configured for thermally coupling to the base module  15 . The printed circuit board  18  may be electrically and thermally connected to the one or more solid state lighting elements and thus may conduct heat from the solid state lighting elements  14  to the thermal spreading element  16 . The replaceable illumination module  10  may be removably coupled to the base module  15 . The base module  15  may include a heat sink in thermal contact with the replaceable illumination module  10  via the thermal spreading element  16 . 
     In some embodiments, the replaceable illumination module  10  may include environmental isolation functionality, and thus may provide varying levels for dry, damp, and wet location applications. For example, the replaceable illumination module  10  may be packaged in isolation to prevent moisture penetration to the solid state lighting elements  14  while allowing air flow to dissipate heat via convection. 
     As also shown in  FIG. 1 , the base module  15  may include a thermal management element  20 , base module circuitry  22 , base connector  24 , and air flow channels  26 . Further details regarding embodiments of the base module  15  are provided below. 
     The lighting system may be upgradeable, replaceable, serviceable, and/or modular. In some embodiments, the modularity of the lighting system may enable the user to mix and match various components as required per specific applications. For example, in certain embodiments, a predetermined base component (e.g., base module or base module component) may be coupled to a predetermined adaptor component, such that the same component may be used in a different application type. The modularity of the lighting system and/or the replaceable illumination module  10  may entail substantially similar form factors of certain components, e.g., for interchangeability. 
     In some embodiments, the lighting system may be of the same form factor as that of prior art lighting systems, while providing luminous output equivalent to or exceeding such systems. For example, in the illustrated embodiment of  FIG. 1 , the lighting system may be a direct “drop in” replacement for prior art lighting solutions, e.g., incandescent bulbs, compact fluorescent bulbs, etc. In some embodiments, the lighting system may have a size envelope that is compatible with applicable ANSI standards and may operate directly from 120 or 240 VAC power. In some embodiments, solid state lighting elements  14  may include a plurality of LEDs. The lighting system may be used as a direct replacement for LED light bulbs and other prior art lighting systems. For example, in the illustrated embodiment, the lighting system may not require additional ballasts or additional fixtures. 
     In some embodiments, the replaceable illumination module  10  may provide an optimized heat transfer interface through use of an underlying conductive structure.  FIG. 2  illustrates an embodiment of a replaceable illumination module  10  with an interface connection, specifically, an illumination module interface  30 , which may prevent insufficient thermal connection, deleterious high LED temperature, and/or premature device failure. The illumination module interface  30  may facilitate or even optimize heat transfer. For example, in the illustrated embodiment, illumination module interface  30  may entail or apply sufficient pressure to control the gap spacing between the illumination module interface  30  and an integrated electrical and mechanical connector  36  (and/or the heat sink), which may also be referred to herein simply as “connector  36 ”. Thus, the illumination module interface  30  may include a gap spacing that may improve (and in some embodiments may optimize) heat transfer between the illumination module interface  30  and the integrated electrical and mechanical connector  36 . In some embodiments, the gap spacing may be filled with an interface thermal enhancement  34 . The interface thermal enhancement  34  may include heat conductive materials such as solid pads which may be placed at the interface. These materials may not melt or change phase at operating temperatures of the lighting system. In some embodiments, the gap spacing may be filled with materials that may be constructed of metal or ceramic filled silicone elastomer. Alternatively, the gap spacing may be filled with thermal grease, which may be metal or ceramic filled silicone or a synthetic based compound. 
     The illumination module interface  30  may maintain a compressive force through coupling with a conductive film, a potting compound, or a conductive pad which modifies or maintains effective thermal conductivity across the interface. For example, illumination module interface  30  may include a compressive force that may modify or maintain the thermal conductivity across the illumination module interface  30 . In some embodiments, the illumination module interface  30  may maintain a pressure above a predetermined critical value that may increase the thermal conductivity that prevents a deleterious temperature rise at the solid state lighting elements  14 . 
     In one embodiment, sufficient compressive force at the illumination module interface  30  may be achieved via spring loading via a predetermined and pre-set spring force. In various embodiments, the illumination module interface  30  may include standard screw fasteners or assembly method controls to set a predetermined compressive force. Alternatively, or additionally, the illumination module interface  30  may include Bayonet type connectors to engage a fastener until a stop point is reached to attain a predetermined force. 
     In some embodiments, the integrated electrical and mechanical connector  36  may provide maximum contact area with the illumination module interface  30  via interface thermal enhancement  34  to maintain heat conduction. Moreover, in one embodiment, the connector  36  may prevent power provision to replaceable illumination module  10  unless sufficient interfacial contact with the illumination module interface  30  is made to ensure heat removal. In other words, connector  36  may allow solid state lighting elements  14  to be powered on only when a predetermined thermal path is defined as being appropriate. 
     The illumination module interface  30  may include thermal conduction mechanisms that scale with contact area. For example, the illumination module interface  30  may include a high degree of planarity to insure maximum contact area with the interface thermal enhancement  34 . The interface thermal enhancement  34  may include phase change materials, which may be solid pads at room temperature that melt at the operating temperature to form a substantially intimate interface between components. 
     In various exemplary embodiments, the interface thermal enhancement  34  (heat conductive materials) may include one or more of the following:
         a silver loaded grease that may provide superior thermal performance, e.g., high-filling silver particles, which may be micro-ionized, and/or ceramic particles, which may be thermal conductive ceramic particles, such as, for example, Arctic Silver® 5 high-density polysynthetic silver thermal compound.   carbon based products for heat spreading and interface conduction which combine enhanced flexural properties with exceptional thermal properties of high conductivity flexible graphite, such as, for example, GrafTech International Spreadershield™ Flex formable heat spreader.   material of low contact resistance and high thermal conductivity at low clamping loads, such as natural graphite and polymer additive, e.g., GrafTech International Hitherm™ thermal interface material.   a thermal gap filler product that may conform to surface irregularities and replace air with a much higher thermal conductivity material, thereby increasing heat transfer, e.g., Laird Technologies® thermal gap filler pad.   a thermal phase change material that may be a solid pad at room temperature, may melt at operating temperatures forming intimate contact on mating surfaces to produce thermal resistance, may provide superior surface wetting and minimum bond thickness, and may actively expel entrapped air, e.g., Laird Technologies® phase change material.   compressible phase-change thermal interface materials or in-situ curing thermal interface adhesive materials that enable the filling of large gaps between heat-spreader and heat generating components that have substantial differential heights, e.g., AI Technology Inc. Cool Bond® products.   thermal greases, which may be non-silicone based and non-migrating, may include an in-situ curing thermal interface, or may include a reworkable, silver filled, thermally conductive paste, e.g., AI Technology Inc. Cool Grease® products.       

     Note that in some embodiments, the illumination module interface  30  may be made substantially planar via grinding, polishing, or another finishing technique to minimize roughness of mating surfaces. 
     As  FIG. 2  also illustrates, in some embodiments the beam conditioning elements or components  12  may include one or more beam conditioning optical elements  32 . The one or more beam conditioning optical elements  32  may be proximate to the one or more solid state lighting elements  14  and may be configured to modify light output from the solid state lighting elements  14  to produce a specified beam. More specifically, the beam conditioning optical elements  32  may be configured to control color temperature during operation of replaceable illumination module  10 . For example, at least one of the beam conditioning optical elements  32  may be configured to spectrally transform light from the one or more solid state lighting elements  14  by absorbing photons with a first spectral distribution and emitting photons with a second spectral distribution. In some embodiments, at least one of the one or more beam conditioning optical elements  32  may include one or more of: a phosphor material or compound, a nanophotonic material, a crystalline photonic material, an optical fiber material, a photonic crystal fiber material, an engineered microstructure material, or a dielectric waveguide material. 
     Note that in some embodiments, the one or more solid state lighting elements  14  may include a plurality of solid state lighting elements  14 , where at least two of the solid state lighting elements  14  each has a respective specified spectral output, and where at least one of the beam conditioning optical elements  32  is configured to homogenize light output from the plurality of solid state lighting elements  14 , where homogenizing light output refers to light mixing or powering solid state lighting elements  14  at multiple wavelengths to achieve a desired spectrum. 
     The beam conditioning optical elements  32  may enhance spectral performance by improving color temperature control and may improve the color rendering index of replaceable illumination module  10 . In some embodiments, spectral transformation components may be thermally decoupled from the solid state lighting elements  14 , thereby enhancing efficiency and spectral performance of the replaceable illumination module  10 , possibly by reducing or eliminating undesirable aspects of the spectral performance of the solid state lighting elements  14 . In some embodiments where beam conditioning  12  includes modification of the spectral distribution of the output light, beam conditioning  12  may include spectral modification and color temperature alteration. For example, beam conditioning  12  may include filters for removing portions of the spectrum, or thin film reflective and/or transmissive structures for increasing or decreasing intensity of selected wavelengths. 
     Additionally, at least one of the beam conditioning optical elements  32  may include one or more beam forming elements that may be configured to modify a spatial intensity distribution of the photons of the second spectral distribution for control of beam concentration and beam divergence. The beam forming elements may include at least one of: one or more reflective optical elements, e.g., parabolic reflectors for light collection and directional beam output, one or more diffractive optical elements, e.g., one or more of Fresnel lenses, or one or more refractive elements, e.g., prism structures that use total internal reflectance to control and minimize beam divergence. 
     In some embodiments, beam conditioning element(s) or component(s)  12  may enable an intensity distribution output by the replaceable illumination module  10  to match illumination characteristics of an existing lighting fixture, e.g., uniform illumination over a predetermined distribution range. Thus, beam conditioning may include spectral distribution of the light, and may also include spatial distribution of the light, referred to as beam forming. Thus, one or more of the beam conditioning elements may be beam forming elements. 
     In various embodiments, the distribution range of the beam conditioning (forming) element(s) or component(s)  12  may be small, such as with a spot light, or, in the case of an Edison configuration, beam conditioning  12  may enable a large and diffuse distribution range. 
     As noted above, in some embodiments the base module may include a heat sink.  FIG. 3  illustrates one embodiment of a functional decomposition of the replaceable illumination module&#39;s interface connection to heat sink  44 . In the embodiment shown in  FIG. 3 , the replaceable illumination module  10  includes the above-described solid state lighting elements  14 , printed circuit board  18 , thermal spreading element  16 , illumination module interface  30 , and interface thermal enhancement  34 , as well as a cover cap  38 , fastener  40 , electrical connector  42  (described in more detail below with respect to  FIG. 24 ), and heat sink  44 . In some embodiments, integrated electrical and mechanical connector  36  may include electrical connector  42 . 
     The heat sink  44  may couple to the thermal spreading element  16  via the illumination module interface  30  and interface thermal enhancement  34 , which in turn may be coupled with the solid state lighting elements  14 . The replaceable illumination module  10  may thus provide a continuous thermal path from the solid state lighting elements  14  to thermal spreading element  16  through illumination module interface  30  (and interface thermal enhancement  34 ) to heat sink  44 , thereby providing a thermal conduction path from the solid state lighting elements  14  to the surroundings, i.e., to the environment of the lighting system. Additionally, in some embodiments, printed circuit board  18  may be made of the same material as thermal spreading element  16 , or may be mounted on thermal spreading element  16 . In other words, thermal spreading element  16  may be part of the infrastructure of printed circuit board  18 . 
     In some embodiments, the electrical connector  42  of  FIG. 3  may couple the solid state lighting elements  14  to the base module circuitry  22  (via the printed circuit board  18 ), thereby providing an electrical conduction path. For example, the electrical connector  42  may include at least one electrical lead that may be couple to the base module circuitry  22 . As described in more detail below, in various embodiments, the base module circuitry  22  may implement any of various functionalities, including for example, power conditioning circuitry, control circuitry, or a driver circuit, among others. Thus, in embodiments where the base module circuitry  22  includes a driver circuit, the at least one electrical lead may electrically couple the solid state lighting elements  14  to the driver circuit (again, via the printed circuit board  18 ). Note that the base module circuitry  22  may include one or more base module printed circuit boards. 
     In some embodiments, the replaceable illumination module  10  may include a cover cap  38 , which may provide one or more functions for the lighting system. For example, in one embodiment, the cover cap  38  may operate as a beam conditioning element  12  (see  FIG. 1 ), facilitating transmission, e.g., dispersion, of light output from the solid state lighting elements  14 , and/or may isolate the solid state lighting elements  14 , printed circuit board  18 , and/or other components of the replaceable illumination module  10  from environmental intrusions, as noted above. 
     Said another way, cover cap  38  may be affixed to printed circuit board  18 , and may protect the one or more solid state lighting elements  14  and printed circuit board  18  from environmental intrusions and may also diffuse light from the one or more solid state lighting elements  14 . In some embodiments, at least a portion of cover cap  38  may be made of a smart material to block moisture while supporting convective heat transfer. For example, the smart material may include one or more of: a thermally conductive material with thermal conductivity of at least approximately 0.9 W/m-K or a porous material with a pore density of at least approximately 10 7  pores/cm 2 . More generally, replaceable illumination module  10  may include smart materials that allow for airflow while preventing moisture penetration. 
     More specifically, replaceable illumination module  10  (e.g., cover cap  38 ) may include micro-weave materials with pore sizes large enough for air/molecular transfer but too small to convey water droplets; these materials may be woven polymer fibers (e.g., GORE-TEX®), sintered metals or ceramics, ceramic fiber based, or other combinations with pore size in the appropriate range. In further exemplary embodiments, the smart materials may include materials such as Saint Gobain Thermocool® thermally conductive fabric (silicon based foam), porous polytetrafluoroethylene (PTFE) fabric, and/or sintered materials. In some embodiments, sintered materials may be produced from plastic, metal and ceramic fibers, spheres, and/or powders. 
     The cover cap  38  may be secured to replaceable illumination module  10  by use of a pressure fit with thermal spreading element  16 . For example, cover cap  38  may include a retention means, such as a hook-shaped feature, so that the cover cap  38  may snap in place over the printed circuit board  18 . In a further embodiment, cover cap  38  may be coupled to the printed circuit board  18  via a tension fit, which may occur via retention hooks. 
     Fastener(s)  40  may couple the thermal spreading element  16  to heat sink  44 . In other words, the thermal spreading element  16  may be held in thermal contact with heat sink  44  via a fastening means, such as a connector, that maintains a specified interfacial force between the thermal spreading element  16  and the heat sink  44 . Thus, for example, in the illustrated embodiment, a continuous thermal path may be provided from the illumination module interface  30  to thermal spreading element  16  to heat sink  44 . In certain embodiments, fastener  40 , when installed, may be fastened to a complementary threaded hole included in or coupled to a shaft of the base module  15 , described in more detail below with reference to  FIGS. 5 and 6 . In some embodiments, fastener  40  may include a common type of screw, such as a Phillips head, flat-head, hex-head screw, that can be tightened or loosened using a common tool, such as a screw driver or an Allen wrench. Fastener  40  may be coupled with a complementary screw boss, which may not be pre-threaded. Fastener  40  may be threaded and may a self-tapping screw, a thread-forming screw, a Avdel Rivscrew, or a PEM stickscrew, among others. 
     In some embodiments, fastener  40  may be coupled to a complementary screw boss, which may be included in heat sink  44 . Similarly, circular features included in or coupled to heat sink  44  may include a complementary screw boss that couples with fastener  40 . 
       FIG. 4  illustrates an embodiment in which the illumination module interface  30  includes at least one thermally conductive pier  40 . The pier  40  may be a substantially columnar structure that may increase contact area between the illumination module interface  30  and interface thermal enhancement  34 . The pier  40  may conduct heat from the replaceable illumination module to heat sink  44  (described in further detail below with reference to  FIGS. 7 and 8 ). The thermally conductive pier  40  may be constructed of high thermal conductivity metal, such as aluminum or copper, and may be held in thermal contact with the replaceable illumination module  10  to transfer heat produced by the solid state lighting elements  14 . In one embodiment, the at least one thermally conductive pier  40  may be inserted into mating features on heat sink  44 . Moreover, contact between the at least one thermally conductive pier  40  and the heat sink  44  may be augmented via a substantially close fit, spring, or other compressive force, thermal greases, or other means. Heat conduction from the replaceable illumination module  10  to the at least one thermally conductive pier  40  may also be enhanced through the use of thermoelectric cooler devices, described below. 
       FIGS. 5 and 6  illustrate exemplary embodiments of a shaft and base connector assembly  50  for coupling to a replaceable illumination module. As shown in  FIG. 5 , shaft and base connector assembly  50  may include base connector  24 , shaft  60 , base adaptor  64 , and base module circuitry  22 , where the base adaptor  64  may couple base connector  24  with shaft  60 . 
     In some embodiments, base connector  24  may included a threaded fastening means that may be coupled to a complementary aspect linked with a lighting fixture. For example, in the illustrated embodiment, base connector  24  may be screwed into a complementary threaded socket of a lighting fixture. In other embodiments, base connector  24  may include a bi-pin base or a twist-lock means. In some embodiments, base connector  24  may be or include a fitting, wireway, or strain relief bushing. 
     In some embodiments, base connector  24  may be in accordance with an American National Standard and/or an IEC lamp base standard. For example, the base connector  24  may be configured to fit the American National Standard ANSI ANSLG C81.67-2007 standard. In various exemplary embodiments, base connector  24  may be associated with a BA15 Candelabra single-contact or double-contact bayonet base, a BAY15s or BAY15d base, a BAZ15d base, a E26 medium screw thread, a E39 mogul screw thread, a EP39 position-oriented mogul screw base, a EX39 exclusionary mogul screw base, a G13 medium Bipin base, a P8.25d base, a P12.4d base, a R17d recessed double-contact base, an E29/28 single contact Admedium screw base, or a E2/53×39 skirted Admedium screw base, among others. 
     In one embodiment, base connector  24  may be inserted into a complementary recess of an existing lighting fixture. For example, base connector  24  may be installed, fastened, or removed via a screw motion into a complementary recess of an existing lighting fixture. Thus, for example, base connector  24  may be electrically coupled to a complementary recess of an existing lighting fixture upon substantial insertion into an existing lighting fixture. Thus, in certain embodiments, a user may install or uninstall replaceable illumination module  10  into and out of an existing lighting fixture. In certain embodiments, replaceable illumination module  10  may be a modular system that may be configured to create various types and purposes of lighting fixtures, including for track lighting replacements, sconces, exterior lighting fixtures, emergency lighting, work lighting, film and video lighting, accent lighting fixtures, moving fixtures, and articulated mountings for various purposes. 
     As discussed above, base module circuitry  22  may include a driver circuit. Situating the base module circuitry, and thus the driver circuit, in the base module rather than the replaceable illumination module may provide for field replacement of LEDs (e.g., via replacement of the replaceable illumination module  10 ). Similarly, the driver circuit may be replaced independently of the illumination module (also referred to as a light engine). Thus, by replacing base module circuitry  22 , including the driver circuit, the driver circuit may be upgraded to support additional or improved lighting features and functions, i.e., base module circuitry  22  may enable ease of feature change via a replacement that supports additional capabilities. For example, the driver circuit may be replaced with an improved efficiency driver circuit that may make replaceable illumination module  10  to be more efficient. In various other exemplary embodiments, the base module circuitry  22  may include upgradeable capabilities which may enable base module circuitry  22  to be upgraded to an improved energy efficient driver circuit, to be upgraded to a networked or smart device, to be upgraded to support next generation technology, or to be upgraded to integrate higher efficiency emitter technology, among others. 
     More generally, replacing the base module circuitry  22 , which may include one or more of the driver circuit, power conditioning circuitry, or control circuitry, may facilitate easy modification or upgrades to the lighting system. For example, the base module circuitry  22  may be replaced to improve a power factor and/or reduce total harmonic distortion for the lighting system. As further examples, the base module circuitry  22  may be replaced in case of a field failure of the driver circuit, or may be serviced due to prematurely failed components and consequently replaced. 
     Thus, while prior solutions use non-modular drivers/power supplies and so forth, embodiments of the present invention may provide not only a replaceable illumination module  10  that may be upgradeable or replaced, but may also provide a base module circuitry  22  that, while substantially encapsulated by shaft and base connector assembly  50  of the base module, may be accessible to promote upgrades or replacements. 
       FIG. 6  illustrates an embodiment of the shaft and base connector assembly  50  that further includes printed circuit board header  70 , and a complementary connector  68 , although in other embodiments either or both of these elements may be omitted or replaced with other elements. 
       FIG. 7  illustrates an embodiment of the lighting system that includes an exemplary heat sink  44  coupled to shaft and base connector assembly  50  via shaft  60 . As shown, in this exemplary embodiment, the heat sink  44  includes one or more heat fins  46 . In some embodiments, the heat sink  44  may be extruded, as discussed in detail below. 
     The use of heat sink  44  may prevent deleterious failure modes that can occur when the operating temperature of the illumination module exceeds some nominal value. For example, the heat sink may prevent thermal degradation of the p-n junction on the (lighting) die, may prevent phosphor performance degradation and increase the life span of the replaceable illumination module  10 , may prevent spectral shift in the light output from the illumination module  10 , or may prevent out of specification color temperature and luminosity performance, among other benefits. 
     Additionally, the lighting system may include cover cap  38  and base connector  24 , both described above in detail. As may be seen, the replaceable illumination module  10  may not be visible under the cover cap  38 . In some embodiments, cover cap  38  may be configured to package extruded heat sink  44 . For example, in the illustrated embodiment, cover cap  38  may minimize manufacturing costs by eliminating heat sink machining operations. Additionally cover cap  38  may provide integration locations and enclosures for sensors and other advanced control devices. 
     In some embodiments, heat sink  44  may be coupled to shaft and base connector assembly  50  with an interference or press fit. For example, heat sink  44  may be coupled to shaft  60  by a predetermined controlled pressure, e.g., by a user applying a predetermined torque with a plurality of screws. In some embodiments, heat sink  44  may be upgradeable, replaceable, serviceable, and/or modular, such that heat sink  44  may be easily substituted with a replacement heat sink, e.g., with a new or improved heat sink for improved functionality. Moreover, the heat sink  44  may be temporarily removed such that other components of the lighting system may be substituted with replacement components. As used herein, the end or portion of the heat sink nearest to the replaceable illumination module is referred to as the “proximal” end or portion, and the end of the heat sink furthest from the replaceable illumination module is referred to as the “distal” end or portion. 
       FIG. 8  illustrates an exemplary heat sink, according to one embodiment. In some embodiments, the heat sink  44  may be made at least partially from a material with a predetermined thermal conductivity. For example, the material may have a thermal conductivity of at least approximately 180 W/m-K. In one exemplary embodiment, heat sink  44  may include or may be made of a high thermal conductivity aluminum material. Moreover, in some embodiments, the heat sink  44  may include a planar surface, e.g., for thermal contact with the thermal spreading element  18 . 
     The heat sink  44  may include a heat sink boss  48 , which may provide for alignment of heat sink relative to shaft and base connector assembly  50  (see, e.g.,  FIGS. 5 and 6 ). In some embodiments, the heat sink boss  48  may provide a thermal path which may facilitate the transfer of heat from the solid state lighting elements  14  to the thermal spreading element  16 , through the illumination module interface  30  and interface thermal enhancement  34 , to heat sink  44 . 
     As shown in  FIG. 8 , the heat sink  44  may include a plurality of heat fins  46 , which may provide increased life span for the replaceable illumination module  10  by providing heat transfer from replaceable illumination module  10  to the surroundings. For example, in the illustrated embodiment, heat sink  44  may include a plurality of radial heat fins  46 , which may enhance thermal transmission to the surroundings by conductive heat dissipation. As  FIG. 8  also indicates, in some embodiments, each heat fin may have a specified nonzero curvature. 
     In some embodiments, the heat sink  44  may be manufactured via an extrusion process, discussed in detail below. In other words, the heat sink  44  may be or include at least one extrusion. Moreover, as  FIGS. 7 and 8  show, the at least one extrusion may include a plurality of heat fins  46 , where, as indicated above, the plurality of heat fins  46  may be made of a material with a thermal conductivity of at least approximately 180 W/m-K, and where, as  FIG. 1  shows, the plurality of heat fins  46  may form a plurality of air flow channels  26  for convectively dissipating heat. 
     In some embodiments, heat sink  44  may be tapered. For example, the heat sink  44  may have a monotonically increasing or monotonically decreasing radius along the axis of the structure, where the proximal end of the heat sink has a larger diameter than the distal end. Thus, the at least one extrusion may be a tapered extrusion. 
       FIG. 9  illustrates a tapered heat sink with heat fins  46  via exemplary proximal (left)  71  and distal (right)  72  cross-sections, according to one embodiment. As may be seen, in this illustration, the proximal cross-section  71  of the heat sink has a larger outer diameter (Do) than that of the distal cross-section  72 , and so the heat sink is tapered, as indicated by  75 . In this exemplary embodiment, the proximal cross-section  71  also has a larger inner diameter Di than that of the distal cross-section  72 , although it should be noted that in some embodiments the inner diameters may be the same, i.e., the inner diameter of the heat sink may be constant. Note that there are a number of ways to produce such a tapered heat sink. Embodiments of a novel method of extruding such a heat sink are described below with reference to  FIG. 25 . 
     Other geometries are also contemplated. For example,  FIG. 10  illustrates an exemplary embodiment in which the heat sink is both tapered  75  and twisted  76  to further increase heat fin  46  surface area in a given volume. The twist  76  is indicated by the four arrows arranged counter-clockwise around the left cross-section. Note that such a twist imparted to the heat sink results in spiraling heat fins, as indicated by  74 , which shows the resulting change in angular position of the cross-section of a given heat fin from the proximal cross-section to the distal cross-section of the heat sink. Embodiments of a novel method of extruding such a heat sink are also described below with reference to  FIG. 25 . 
     In some embodiments, heat sink  44  may include a plurality of constituent heat sinks, which may be stacked. Each of the plurality of constituent heat sinks  44  may be of different outer diameters with a common center and internal diameter, and may be mounted on a common counter-shaft. In some embodiments, the plurality of constituent heat sinks  44  may be fused together. Thus, in embodiments where the heat sink is made via an extrusion process, the heat sink  44  may include a plurality of stacked extrusions, where each stacked extrusion has a respective radius. The plurality of stacked extrusions may be ordered in accordance with their respective radii to form a stepwise tapered heat sink  44 . As used herein, “stepwise tapered” refers to a structure similar to a (possibly inverted) wedding cake, as shown in  FIGS. 1 ,  11 ,  12 , and  13 . In some embodiments, the heat fins  46  of at least one of the plurality of stacked extrusions may not be aligned with the corresponding heat fins  46  of at least one adjacent stacked extrusion. In other words, the corresponding heat fins of adjacent extrusions may be offset or staggered with respect to one another. 
       FIG. 11  illustrates an exemplary lighting fixture in relation to one embodiment of the lighting system  100  disclosed herein. In some embodiments, the lighting system  100  may be coupled to lighting fixture  80 , which may be part of or installed in ceiling element  82 , e.g., a ceiling tile. In other embodiments, lighting fixture  80  may be fixed to or located near ceiling element  82 . 
     In some embodiments, the lighting system may serve as a replacement for or in an existing lighting fixture. For example, the lighting system  100  may be a retrofit to an existing lighting fixture and thus may enable replacement of the LED lamp by the lighting system  100 . In some embodiments, replaceable illumination module  10  combined with exemplary heat sink  44  may reduce the cost of ownership over that of competing technologies and substantially mitigate the environmental impact of failed units through its reuse. Moreover, in some embodiments, the replaceable illumination module  10  may itself be a replacement for an older or less functional illumination module in a lighting system as disclosed herein, while retaining use of the (original) heat sink  44 . 
     In some embodiments replaceable illumination module  10  may include a base configuration that may conform to an existing commercially available lighting unit. For example, replaceable illumination module  10  may include screw threads, which may be of an Edison configuration, pin bases, and bayonet mounts, or may mimic the function of existing spot, flood, and Edison (standard light bulb or capsule) lights. In some embodiments, replaceable illumination module  10  may conform to specific light wavelength requirements of an existing lighting fixture. For example, in various embodiments, the replaceable illumination module  10  may specifically support plant growth cycles in agricultural applications or may support certain spectral modes, such as short wavelength for enhancing image resolution, in imaging applications, among others. In other words, various models of the replaceable illumination module  10  may be provided that may be particularly suitable for specific applications. 
     Thus, with specific reference to  FIG. 11 , in some embodiments, the lighting system  100  may function as a retrofit LED lamp, which may be coupled to lighting fixture  80 , where lighting fixture  80  may be an existing lighting system, such as a R/PAR 38, R/PAR 30, R20, MR16, A19, T8, or PLD CFL stick, among others. Moreover, in various embodiments, lighting fixture  80  may be a cobra head street light, security street light, parking lot light, parking garage light, high bay light, low bay light, stairway light, low profile light, or runway light, among others. 
     The lighting system  100  may be configured to promote convective heat transfer from replaceable illumination module  10  to the surroundings. For example, in the illustrated embodiment, the lighting system  100  may be aligned to promote density driven air flow through the plurality of air flow channels of heat sink  44 . 
     In some embodiments, effective or improved heat extraction from illumination module  10  may be achieved by heat sink  44  by use of multi-fin and/or bifurcated designs. The heat sink  44  may promote heat transfer from replaceable illumination module  10  to the surroundings by use of the thermal material of heat sink  44 , e.g., via conduction and/or radiation, and in some embodiments may also promote heat transfer by convective means. 
     Referring again to  FIG. 8 , heat sink  44  may include a plurality of heat fins  46  such that spacing between a pair of heat fins  46  may provide for air flow channels  26 . For example, in the illustrated embodiment, heat sink  44  may include air flow channels  26  to promote maximal heat extraction by convection. In other words, in some embodiments, a plurality of air flow channels  26 , which may be air flow channels, may convectively transfer heat from replaceable illumination module  10  to the surroundings. For example, the air flow channels  26  may utilize thermal/density driven air flow to promote convective heat loss to the surroundings, e.g., may promote passive cooling to induce heat transfer from heat sink  44 . 
     Moreover, in further embodiments, the air flow channels  26  may be used in conjunction with at least one active cooling apparatus to induce heat transfer from replaceable illumination module  10 . For example, thermal management element  20  (shown in  FIG. 1 , and which includes heat sink  44 ) may include any of various forced convective means to further enhance heat extraction from replaceable illumination module  10 , which may drive additional temperature isolation of replaceable illumination module  10  from ambient conditions, and may also help meet applicable environmental requirements. In some embodiments, a recessed can, such as shown in  FIGS. 11 and 12 , which accommodate shaft and base connector assembly  50  (see, e.g.,  FIGS. 5 and 6 ), may also contribute to enhanced heat removal from replaceable illumination module  10 . 
     In certain embodiments, convective enhancements of replaceable illumination module  10  may be theoretically modeled and analytically estimated as flow over a constant-temperature body of arbitrary shape. For example, the convective enhancements may be estimated through a calculation of heat transfer through a laminar boundary layer on a body of arbitrary shape, which may involve solving a momentum equation to establish the velocity field and then solving an energy equation. This theoretical process may be performed with any desired degree of precision by use of a finite difference procedure or an approximate solution from momentum and energy integral equations. 
     In other embodiments, the analytical estimation of convection heat transfer may involve solving either the momentum or energy integral equation for a constant surface temperature with an arbitrary free-stream velocity variable based on the energy integral equation, in which case, the rate of growth of the thermal boundary-layer thickness may be a function of local parameters: 
     
       
         
           
             
               
                 
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     where 
     Δ is the thermal boundary-layer thickness, 
     u ∞  is velocity in the free stream at the outer edge of the boundary layer, 
     
       
         
           
             
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     is the rate of change of the free stream velocity, 
     v is the kinematic viscosity, and 
     Pr is the Prandtl Number. 
     In further embodiments, the convective enhancements in replaceable illumination module  10  may be theoretically modeled and analytically estimated as flow of a body of arbitrary shape and an arbitrarily specified surface temperature. Convective flow over replaceable illumination module  10  may thus include solving first the momentum equation for a predetermined free-stream velocity, and then the energy equation for a varying surface temperature. Direct numerical solutions of differential equations of the boundary layer may provide a temperature estimation of the variable-surface-temperature for flow for a body over which the free-stream velocity varies. 
       FIG. 12  illustrates an exemplary embodiment of various convective enhancements to the lighting system  100 . As discussed above, in some embodiments, the lighting system  100 , which may be or operate as a retrofit LED lamp, may be coupled to lighting fixture  80 , e.g., to provide induced natural convection  88 , as  FIG. 12  indicates graphically. Additionally, as  FIG. 12  also shows, in some embodiments, the lighting system may include an air flow baffle  86  to further increase convection. For example, the heat sink may be encircled by the air flow baffle  86 , which may increase the convective heat transfer coefficient with induced natural convection  88 . The air flow baffle  86  may interrupt the hydrodynamic and thermal boundary layers and form a recirculation zone between the surface of the lighting system  100  and the lighting fixture  80 . This recirculation zone has the effect of moving cooler ambient air into contact with heat sink  44 . In other words, the flow baffle  86  may encircle heat sink  44  and may utilize a temperature differential to promote convective heat transfer away from heat sink  44 . 
     Thus, in some embodiments, induced natural convection  88  may be implemented or facilitated by thermal management element  20  in combination with replaceable illumination module  10 , air flow baffle  86 , and/or a temperature differential between the lighting system  100  and the surroundings. Additionally, in some embodiments, induced natural convection  88  may be promoted by the use of smart materials (e.g., in the cover cap) to block moisture while supporting convective heat transfer enhancements of the replaceable illumination module  10 . 
     In some embodiments, thermal management element  20  may include a standard rigid package or a flexible/conformable substrate, and may include high thermal conductivity metals that may be configured as a surface flash treatment or in bulk to convey heat. 
       FIG. 13  illustrates further details regarding convective enhancements to an embodiment of the lighting system  100  in relation to the exemplary lighting fixture  80 , where, for example, the lighting system  100  may serve as a retrofit LED lamp. To provide transfer of heat from a higher temperature surface to a lower temperature surface, the surface of the solid state lighting elements  14  may be below the shaft and base connector assembly  50 , and thus, the air surrounding solid state lighting elements  14  may be at higher air temperature  90  than the air surrounding shaft and base connector assembly  50 , which may be at lower air temperature  92 , and so will rise to the top of the fixture cavity, e.g., the fixture “can”. As also shown in  FIG. 13 , once the air reaches the top of the cavity and has cooled, it will flow downward and either exit the fixture, or reheat and re-circulate. 
     Other passive cooling techniques or devices may be used as desired. In some embodiments, the thermal management lighting system may include a passive cooling element coupled to or included in replaceable illumination module  10 , where the passive cooling element includes one or more of: a heat pipe, a Venturi effect device, or a convective flow device, among others. 
     In some embodiments, the lighting system  100  may include active cooling means in addition to such passive convective cooling means.  FIG. 14  illustrates use of an exemplary piezoelectric device  96  in the lighting system  100 , according to one embodiment. Actually, the illustrated embodiment includes two such devices, one on either side of the shaft and base connector assembly  50 , although it should be noted that any number of such devices may be used as desired. The piezoelectric device  96  may include a biomorph piezoelectric structure that includes two plates or layers with piezoelectric layers having opposite polarities, here seen edge on. The two plates may be referred to as a dual plate. A voltage may be applied to the piezoelectric device  96 , thereby causing the two plates of the biomorph piezoelectric structure to respectively expand and contract at the same time. The resulting size differential causes the dual plate to deflect to one side. Supplying this exemplary piezoelectric device  96  with an alternating current may thus cause successive deflections from side to side, thereby fanning or waving the air, pulling air away from the solid state lighting elements  14 , and increasing air flow through the heat sink  44 . 
     In another embodiment, one or more piezoelectric bellows may be utilized, where a chamber with one or more piezoelectric walls is periodically pulsed to “puff” air in a specified direction, e.g., by repeatedly expanding or contracting the volume of the chamber, causing air to be successively taken in and expelled. In other embodiments, any types of piezoelectric devices or techniques may be used as desired, e.g., ionization based “fans” with no moving parts, etc. Thus, one or more piezoelectric devices  96  may promote air flow around solid state lighting elements  14  and/or force convective heat transfer through and/or over heat sink  44 , thereby dissipating more heat than passive convection alone. 
     Other active cooling means are also contemplated.  FIG. 15  illustrates an embodiment in which the light system  100  includes at least one tube axial fan  98  (in this particular case, two such fans). The tube axial fan  98  may include a propeller (or, alternatively, a disk-type wheel) within a cylinder (the tube). In certain embodiments, tube axial fan  98  may be either belt-driven or may be connected directly to a motor. The tube axial fan may force convective heat transfer or may induce airflow over heat sink  44  to enhance overall convective heat transfer. 
     In various other embodiments, the lighting system  100  may include one or more of: a thermoelectric cooler, a phase-change device, a voice coil based flipper fan, a synthetic jet cooler, or an acoustically-driven cooler, among others. For example, in an embodiment that uses a thermoelectric cooler, the thermoelectric cooler may be integrated with the heat sink to increase heat fin temperature differential, thereby boosting convective heat transfer. Similarly, the thermal management element  20  may include heat pipes or other phase change devices that may augment heat flow away from the solid state lighting elements  14 . 
     The use of solid state lighting elements  14  provides numerous benefits over incandescent lighting devices. Note, for example, that solid state lighting elements  14  may enable a lumens per watt output of the replaceable illumination module  10  to be substantially higher than that of an incandescent illumination source. Moreover, in some embodiments, solid state lighting elements  14  may enable energy efficiency and thermal efficiency to be substantially higher than that of incandescent illumination source. Moreover, the size and form factor of solid state lighting elements  14  may be packaged for compatibility with ANSI standards. In some embodiments, the life expectancy of replaceable illumination module  10  may greatly exceed the life expectancy of incandescent lamps. For example, the life expectancy of replaceable illumination module  10  may be extended through power conditioning and power delivery methods (described in detail herein) that may extend life by minimizing LED “on time” while still supplying sufficient illumination. In certain embodiments, redundant LED elements in replaceable illumination module  10  may extend the life expectancy through de-energizing failed LED elements and powering alternate LED units powered as replacements. 
     Moreover, the lighting system  100  may prevent premature failure of various components. For example, the life expectancy of the illumination module to be at least 30 k hours. Moreover, due to the enhanced heat conduction and convection mechanisms disclosed herein, the lighting system may compactly and intensely distribute light from a plurality of encapsulated light emitting diodes with minimal thermal impact and with selective divergence output, such that éntendue loss is minimized. 
     The solid state lighting elements  14  may be coupled to base module circuitry  22 , which as noted above may include power conditioning circuitry, control circuitry, and/or a driver circuit to enable feasible AC line voltage operation while satisfying cost and packaging constraints. For example, the solid state lighting elements  14  may be optimized for AC line voltage operation and may require minimal power conditioning. 
     In some embodiments, the solid state lighting elements  14  may include DC LED single junctions and arrays, which may increase lumen/watt output and/or improve beam profile characteristics. Light efficiency from solid state lighting elements  14  may be enhanced while simultaneously easing beam conditioning requirements. For example, in some embodiments, solid state lighting elements  14  may include compact LED components with a substantially reduced package size while maintaining an increased 1 m/watt output. For example, in one exemplary embodiment, the target package size of the solid state lighting elements  14  may be on the order of 1 mm 2  while maintaining light output of greater than 100 lm/watt, although these specific values are meant to be exemplary only, and are not intended to limit the size or output of the solid state lighting elements to any particular value. 
     In various embodiments, different types of LEDs may be utilized. For example, the solid state lighting elements  14  may include multicolor LEDs and/or LED arrays, use of which may simplify color temperature and intensity control. Alternatively or additionally, the solid state lighting elements  14  may include organic LED (OLED) modules, which may include flexible substrates that allow integration into heat sink and/or optic structures. For example, the solid state lighting elements  14  may include OLED modules with multicolor pixels that may allow color temperature selection. More generally, the one or more solid state lighting elements  14  may include one or more of: a direct current light emitting diode, an alternating current light emitting diode, a multicolor light emitting diode, a solid state light source, an organic light emitting diode, or a flexible-circuit light emitting diode, among others. 
     In one embodiment, the solid state lighting elements  14  may include flexible circuits, such as a petal shaped flex circuit with attached LED units. In one such embodiment, an electrical connection may contain a flexible membrane and LED mounting using industry standard electronic assembly techniques. The resultant circuit shape may allow for conformal mounting to a surface that may facilitate heat removal. 
       FIG. 16  depicts an exemplary flexible LED module or circuit  110  that may be used in some embodiments of the replaceable illumination module  10 , where, for example, the flexible LED module  110  may be conformed to a central heat removal device for thermal management element  20 . Heat may be conducted from the flexible LED module  10  via a conductor to heat sink  44 . In some embodiments, flexible LED module  110  may permit light output from replaceable illumination module  10  to be highly diffuse and multi-directional. 
       FIG. 17  illustrates an embodiment of the lighting system  100  in an Edison configuration, i.e., where the lighting system has a form factor similar to a standard or typical incandescent bulb, and includes a threaded (screw) base. More specifically, the lighting system with an Edison configuration may be used in place of an Edison-style light bulb. As may be seen, this embodiment includes replaceable illumination module  10  (with flexible circuit, per  FIG. 16 ), as well as heat sink  44 , beam conditioning element  120 , e.g., a diffuser structure or element, and integrated thermal-electrical connector  122 , which electrically and thermally couples the solid state lighting elements  14  to the heat sink  44  and power socket, respectively. Note that in this particular configuration, the replaceable illumination module  10  is isolated in the central area of the diffuser structure or element  120 . In one embodiment, the thermal management element  20  configured in an Edison configuration may include copper and copper alloys and gold flash materials. 
     Thus, in some embodiments, thermal management element  20  may promote thermal conductivity while integrating with a predetermined form factor industry standard and/or maintaining thermal diffusion through multi-directional light output. 
     The solid state lighting elements  14  may be electrically connected in any of various configurations. For example,  FIG. 18  illustrates an embodiment of a series and parallel combination solid state lighting elements chain  130 . Note that a series solid state lighting elements chain may provide for electrical series connection of solid state lighting elements  14  and may provide for voltage drop required to operate from AC line voltage. In some embodiments, the connected solid state lighting elements  14  may be applicable to DC circuits, in which the series chain may provide a drop of a supplied higher DC voltage. Thus, in some embodiments, replaceable illumination module  10  may include a series solid state lighting elements chain  130  that may operate at a higher voltage but at a lower total current. 
     In some embodiments, solid state lighting elements chain  130  may be configured in an anti-parallel combination that may provide luminous output over the complete AC cycle, as per  FIG. 18 . In other words, series solid state lighting elements chain  130  may include one electrical series of a solid state lighting elements chain that may conduct during the positive portion of the AC cycle and another electrical series of the solid state lighting elements chain that may conduct during the negative portion of the AC cycle. Additional electronic elements may be added to the chain  130  to further modify voltage or current parameters during the AC cycle. 
       FIG. 19  illustrates an embodiment of bridge rectification that may be used in some embodiments. Bridge rectification may be represented in an electrical circuit as a plurality of electrical circuit equivalent diodes  140  and/or a plurality of electrical circuit equivalent solid state lighting elements  142 . A plurality of diodes may be used in conjunction with series solid state lighting elements chain  130  to achieve a predetermined voltage drop across the circuit. In some embodiments, exemplary bridge rectification may include full wave rectification that may provide 120 Hz light output. 
     As noted above, in some embodiments the base module circuitry  22  may include power conditioning circuitry which may deliver a specified voltage and waveform without adding undue thermal burden on the system. The power conditioning circuitry may be compact to facilitate packaging requirements while providing required lifecycle performance at minimal cost. In some embodiments, voltage and waveform attributes provided by the power conditioning circuitry may depend on the specific solid state lighting elements  14  used in the replaceable illumination module  10 . For example, solid state lighting elements  14  may include a plurality of LED devices that may be operated from a DC supply in the 2 to 5 V range. 
     In some embodiments, solid state lighting elements  14  may include series combinations of junctions within replaceable illumination module  10  that may provide a voltage drop sufficient to allow operation directly from 120 or 240 VAC power. The solid state lighting elements  14  may operate at low voltage DC signals that may be connected by external circuitry to allow operation at AC line voltage. 
     In some embodiments, the power conditioning circuitry may include a current limiting resistor that may limit the total power dissipation of solid state lighting elements  14 . Color temperature output of the replaceable illumination module  10  may be in part set by power dissipation of the device. Thus, in some embodiments, a fixed resistor may provide the required current limit and fix the color temperature output of solid state lighting elements  14 . In other embodiments, the power conditioning circuitry may incorporate a variable resistor, solid state current source, or other controllable current output device to provide a means of adjusting the color temperature and intensity output of solid state lighting elements  14  and ultimately replaceable illumination module  10 . 
     As noted above, solid state lighting elements  14  may be a plurality of LEDs which may require AC to DC conversion as part of power conditioning circuitry  22 . The power conditioning circuitry may be or include a simple transformer, rectifier, and capacitor to provide a reasonably low ripple DC output. In other embodiments, the power conditioning circuitry may include complex conversion circuits that may be devised or purchased, and may include digital control and/or other enhanced features. 
     For example, the power conditioning circuitry may include pulse width and height modulation circuits. In further embodiments, the power conditioning circuitry may operate to decrease or minimize thermal output by cycling power of a DC LED periodically at a sufficient frequency to achieve desired light output, color temperature, and flicker free operation. This process of modulation may provide a dimmer function for DC LED units. 
     In some embodiments, electrical characteristics of driven components in the lighting system may be used as part of the power conditioning circuitry. For example, diode behavior of the solid state lighting elements  14  junction may implement a rectifier circuit. As discussed above, the plurality of solid state lighting elements  14 , which may be LEDs, may be connected in series in replaceable illumination module  10 , thereby providing a voltage drop to allow direct operation from an AC source; alternatively, or additionally, anti-parallel connection of two or more series chains may effectively self rectify and directly operate from an AC source, where each series chain may output light over half of the AC cycle. 
     In some embodiments, the power conditioning circuitry may include diodes in a bridge configuration to power a series chain of LED units. The total voltage drop may be realized by the drop across exemplary rectifier diodes and the LEDs. Thus, in certain embodiments, the resultant 120 Hz light output may be sufficiently flicker free. 
     Diode characteristics of other circuit components such as thermoelectric coolers may be used as well. For example, thermoelectric coolers may use a p-n junction as part of the heat pump effect and exhibit diode type behavior. In some embodiments, a thermoelectric cooler component may be included as part of a circuit such that the thermoelectric cooler may be energized along with the corresponding series solid state lighting elements chain. Note, however, that other thermal cooling means are also contemplated, as described in detail above. 
     Intelligent Control 
     In some embodiments, the lighting system  100  may include or be included in a controllable lighting system, and may include one or more sensors (e.g., a light sensor) and circuitry for determining status or attributes of the lighting system  100  or its environment, which may then be used to control the system (and/or another system). 
     Thus, for example, the lighting system  100  may include a wavelength (e.g., color) sensor component for modulating color temperature output from replaceable illumination module  10 , where the wavelength sensor component may be included in or electrically coupled to replaceable illumination module  10 . Similarly, the lighting system  100  may include an intensity sensor component for modulating light intensity output from replaceable illumination module  10 , where the intensity sensor component may be included in or electrically coupled to replaceable illumination module  10 . 
     In some embodiments, the lighting system  100  may include at least one temperature sensor included in or coupled to replaceable illumination module  10  or heat sink  44 . The temperature sensor may be configured for use in sensing, feedback, and control of temperature in replaceable illumination module  10 . For example, the temperature sensor may measure temperature of the replaceable illumination module  10  or thermal spreading element  16 , for use in regulating operation of the lighting system. The temperature sensor may be a thermocouple, in which the junction may be in thermal contact with thermal spreading element  16 . 
     The control circuitry may be configured to monitor the temperature via the temperature sensor and control the lighting system to regulate the temperature. For example, to control the lighting system to regulate the temperature, the control circuitry may be configured to deactivate or activate at least one of the solid state lighting elements  14 , or modify power provided to the printed circuit board  66 . 
     As noted above, the lighting system may include at least one active cooling element (e.g., a thermoelectric cooler, a phase-change device, a fan, a piezoelectric fan, a voice coil based flipper fan, a synthetic jet cooler, or an acoustically-driven cooler, among others) coupled to or included in replaceable illumination module  10 . Thus, in some embodiments, to control the controllable lighting system to regulate the temperature, the control circuitry may be configured to deactivate or activate the at least one active cooling element. 
     In some embodiments, the at least one sensor may be configured to couple to an automated control network for regulation of color output, light-intensity output, or temperature in the replaceable illumination module by the automated control network. Moreover, the at least one sensor may be configured to couple to the automated control network wirelessly. 
     More generally, in various embodiments, the lighting system  100 , and possibly the replaceable illumination module  10 , may include one or more sensors, including one or more of: a photosensor, a color sensor, a light-intensity sensor, or a temperature sensor, which in some embodiments, may be coupled to the automated control network (possibly wirelessly) for regulation of color output or light-intensity output in replaceable illumination module  10  by the automated control network. 
     The one or more sensors may be proximate to one or more beam conditioning optical elements  32 , and control circuitry may be coupled to the one or more sensors. The control circuitry may be configured to monitor spectral distribution or intensity distribution of spectrally transformed light from the one or more solid state lighting elements  14  via the one or more sensors and modify at least one or more of the beam conditioning optical elements  32  to control color temperature or intensity distribution of the beam. Thus, the one or more sensors may be configured to measure one or more attributes of replaceable illumination module  10  or its environment, and the control circuitry may be configured to couple (possibly wirelessly) to the automated control network for regulation of color output or light-intensity output of the lighting system by the automated control network, based on the measured attributes. Note that “environment” may refer to the immediate surroundings of the replaceable illumination module  10 , or those external to the lighting system  100 . 
     Said another way, the control circuitry may be configured to monitor the one or more attributes to determine a status of the lighting system via the one or more sensors, and the status may be used to regulate the lighting system or control a system coupled to the lighting system. For example, as described above, in some embodiments, the lighting system  100  includes at least one beam conditioning element or component  12 , and so to control the controllable lighting system, the control circuitry may be configured to monitor light emitted from the one or more solid state lighting elements  14  or ambient light via the light sensor, and control the one or more beam conditioning optical elements  32  to generate a specified beam. Thus, by using various sensors and control circuitry (and possibly the automated control network), any of the various aspects of the lighting system may be monitored and controlled. 
     In one exemplary embodiment, the lighting system  100  may be included in a multi-zoned lighting system, where network control of the lighting system may include occupancy dependent zone control, which refers to detection of occupants in a zone followed by reporting to a network. For example, the lighting system may be included in or coupled to an alarm or notification system. In one exemplary embodiment, the one or more sensors may include one or more of: a motion detector, a smoke detector, a chemical sensor, or a carbon monoxide detector. In further embodiments, the lighting system may include or be coupled to one or more of: a video camera, a still camera, a motion detector, a chemical sensor, or a carbon monoxide detector. Note, however, that these sensors are meant to be exemplary only, and are not intended to limit the invention or its use to any particular set of sensors. 
     In some embodiments, multiple lighting systems  100  may be coupled together to form a lighting network. Additionally, in certain embodiments, multiple exemplary power conditioning and power driver configurations may be incorporated to power more than one replaceable illumination module  10  in a lighting network. 
       FIG. 20  illustrates an embodiment of an automated control system  200  for lighting control, where the automated control system  200  controls at least one building zone, in this case, first building zone  202 , second building zone  204 , third building zone  206 , and so on, up to some M th  building zone  208 . Each building zone may include at least one lighting system, referred to as a “lamp” in  FIG. 20 . For example, in the illustrated embodiment, first building zone  202  includes first lamp  210 , second lamp  212 , and numerically up to Nth lamp  214 , where each lamp is designated with its zone and lamp number, e.g., lamp  1 . 1 , lamp  1 . 2 , . . . ,  1 . n , and second building zone  204  includes first lamp  220  (lamp  2 . 1 ), second lamp  222  (lamp  2 . 2 ), and so on up to Nth lamp  224  (lamp  2 . n ), and similarly for the other zones, up to and including the M th  zone&#39;s lamp m.n  244 . Thus, multiple building zones may each include at least one lamp, which may include at least one replaceable illumination module  10 . It should be noted that while in some embodiments, each lamp or lighting system may include a heat sink  44  coupled to the replaceable illumination module, while in other embodiments, the lamp or lighting system may not include such a heat sink, although other cooling elements or techniques may be used as desired. 
     In some embodiments, the automated control system  200  may implement computer-based control of the solid state lighting elements  14  in a networked lighting system. For example, each lighting system coupled to the automated control system  200  may be controlled independently of one another based on data transported throughout the network. Note that the term “network” refers to any two or more devices that are communicatively connected, which may include lighting systems, controllers, and processers, to facilitate the transport of information for device monitoring and control, data storage, and/or data exchange. 
     In some embodiments, multiple lighting systems may be coupled to the automated control system  200  (network) to implement or facilitate automated lighting applications using a variety of feedback stimuli, which may include space-illumination applications for residential, office/workplace, retail, commercial, industrial, and outdoor environments, among others. 
     At least one of the building zones may include at least one type of smart device. For example, at least one of the lamps in the network may be or include at least one smart device, which may be network addressable, i.e., may have a network address. The smart device may include a sensor, which may enable sensing of at least one building zone, at least one lamp, or at least one replaceable illumination module  10 . 
     In some embodiments, automated control system  200  may include wireless communication of temperature data. For example, one or more sensing devices, which may be or include a plurality of sensors, may sense and determine temperature in the lamp (or replaceable illumination module  10 ), which may wirelessly communicate corresponding temperature data to automated control system  200 , which in some embodiments, may regulate temperature in the replaceable illumination module  10  via wireless automated feedback. 
     In some embodiments, the automated control system  200  may include centralized, web-based control to provide intuitive control that integrates with building automation systems, e.g., HVAC (heating, ventilation, and air conditioning) and security. Thus, for example, automated control system  200  may be linked with time-of-day control to turn off predetermined lamps according to a predetermined schedule. In some embodiments, the automated control system  200  may include or be linked with light level photosensors that detect available daylight and control the lighting system(s) accordingly. Alternatively, or additionally, the automated control system  200  may include or be linked to timers that automatically switch off lights after a predetermined time period. 
     In some embodiments, the automated control system  200  may be linked with occupancy sensors that may detect a human or animal presence, activate one or more lights in the room, and turn off the light(s) when no presence is detected, e.g., when the human or animal leaves the room.  FIG. 21  illustrates use of motion sensing in conjunction with an automated control system  200 . In this embodiment, the automated control system  200  controls first building zone  202  and second building zone  204 , where each building zone may include at least one lamp with motion sense, e.g., may include at least one sensor for motion sensing. For example, in the illustrated embodiment, first building zone  202  includes lamp  1 . 1  with motion sense  250  and additional lamps numerically up to lamp  1 . n  with motion sense  252 , and second building zone  204  may include lamp  2 . 1  with motion sense  254  and additional lamps numerically up to lamp  2 . n  with motion sense  256 . As with the lamps of  FIG. 20 , in various embodiments, each lamp in  FIG. 21  may or may not include a heat sink  44 , but preferably includes a replaceable illumination module  10 . 
     The automated control system  200  may sense motion of an approaching material body, which may be a human, animal, or non-living object, and in response, may initiate some specified functionality with respect to the appropriate building zone prior to the arrival of material body. Thus, for example, lamp  1 . 1  with motion sense  250  may first sense motion of the material body, thereby activating lamp  1 . n  with motion sense  252 , lamp  2 . 1  may subsequently detect the body with motion sense  254 , and so forth, with lamp  2 . n  with motion sense  256  in a predetermined sequentially manner. In this way, illumination may automatically be provided as needed for the moving body. 
     In another embodiment, the automated control system  200  may sense pedestrian traffic within a building fitted with such a network of motion sensing lighting systems (lamps), and when a particular pedestrian is detected may activate at least one building zone prior to the arrival of the particular pedestrian to a predetermined building zone. The automated control system may then activate lighting along direction  280 , e.g., within the first building zone  202 , per the motion of the material body. 
       FIG. 22  is a high-level block diagram of a smart light  300  with integrated sensor functionality that may be used with automated control system  200 , according to one embodiment. As shown, in one embodiment, the smart light  300  may include lamp m.n  302 , which refers to the network addressable functionality of the smart light, data processing driver circuit  304 , sensing device  306 , and illumination module  10 . 
     The smart light  300 , and particularly, lamp m.n  302 , may be coupled to or included in a building zone (see, e.g.,  FIGS. 20 and 21 ). For example, in the illustrated embodiment, the variable letter m of lamp m.n  302  may correspond to the building zone number, and the variable letter n may designate the specific lamp coupled to or included in that particular building zone. Thus, lamp  3 . 2  denote the second lamp  222  of the third building zone  206  of  FIG. 20 . 
     Smart light  300  may include an on-board sensing device  306 , which may be controlled by data processing driver circuit  304  (per an algorithm implemented thereby) to modify and control output of replaceable illumination module  10 . The smart light  300  may be networked with a host controller, which may include an algorithm function that may be remotely programmed or may be resident on the host controller. 
     In some embodiments, smart light  300  may include communication functions that allow the device to be used as part of a network to provide automated or “smart” illumination for commercial and residential applications, as discussed above, where, for example, a lighting zone may include smart light  300  that may be turned on or off as required by occupancy to minimize energy consumption. As also discussed above, networked and zoned smart lights may be controlled such that lighting sectors may be cascaded on and off to provide continuous illumination for people in motion in a building while reducing overall power consumption. More generally, in various embodiments, smart light  300  may be or include an addressed device that may be controlled manually, automatically, or combinations of both, depending on specific application requirements. 
     The sensing device  306  may be a sensor that may be a functional feature of replaceable illumination module  10 . For example, sensing device  306  may sense temperature in replaceable illumination module  10  through measurement of color, motion, and/or light-intensity. The sensing device  306  may thus generate temperature data from replaceable illumination module  10 , and may communicate (possibly wirelessly) that temperature data to an automated control system  200 , which may be coupled to an automated control network. 
     In some embodiments, the smart light  300  may implement advanced functionality and control, e.g., light dimming control, via sensing device  306  and illumination module  10 , where the sensing device may be incorporated in the illumination module. For example, a photo-sensor or other intensity monitoring device may be included in the replaceable illumination module  10 , and may provide intensity feedback which may be used to modify light output of the sensing device  306  based on environmental conditions or user input. 
     In another embodiment, the sensing device  306  may be a color temperature monitoring sensor that may be used for automatic or user based control of the color balance of the output light. For example, sensing device  306  and associated control circuitry may control the color balance of the output light. In some embodiments, sensing device  306  (and associated control circuitry) may change the psychological or emotional ‘feel’ of illumination produced by the replaceable illumination module  10  in a commercial setting, or may change the tone of the output light as natural light changes throughout the day. 
     In one embodiment, the sensing device  306  and replaceable illumination module  10  may include or implement a “nightlight” function, where, for example, the replaceable illumination module  10  may include a low power source that may energize one or more of the solid state lighting elements  14  in replaceable illumination module  10  to produce an unobtrusive or low-level illumination. Thus, in some embodiments, illumination output from replaceable illumination module  10  may be realized with low power consumption. 
     As described above, in various embodiments, sensing device  306  may include any of a wide variety of sensors, including, for example, motion sensing, which may be integrated into replaceable illumination module  10  and used to provide enhanced functionality, such as providing illumination only when people are present, e.g., when high-lighting a featured product in a commercial setting. Thus, the smart light may provide illumination only when individuals are present to reduce overall power cost. In some embodiments, security motion sensing functionality of sensing device  306  may trigger illumination by the smart light if a material body, such as a human, animal, inanimate object, enters the field of view of the sensor. 
     The smart light  300  may include communication functions, as well. For example, communication functions implemented by smart light  300  may provide status feedback and/or remote control and programming functions, which may give the end user or automated control system  200  a means for adjusting intensity and/or color temperature remotely. The smart light  300  may utilize any of various wireless communication means such as Zigbee and other protocols, e.g., USB, or, alternatively, may communicate over an electrical power line coupled to the smart light. 
     As also discussed above, in some embodiments, smart light  300  may include integrated video capability. For example, smart light  300  may include a video camera that may be combined with an on-board illumination source to enhance functionality of the replaceable illumination module  10 . More generally, smart light  300  may include security and loss prevention functionality, as well as commercial and residential lighting automation. 
     It should be noted that any of the features and components discussed above may be used in any combinations as desired. For example, in various embodiments, the lighting system may include the thermal management functionality, e.g., heat sink  44 , and beam conditioning functionality, but may omit network control functionality; or may include network control and sophisticated sensor functionality, but may omit the heat sink  44 , and so forth. 
     Described below are embodiments of methods of operation, use, and manufacture, of the lighting device. 
       FIG. 23  is a flowchart diagram of a method for using replaceable illumination module  10 , according to one embodiment. The method shown in  FIG. 23  may be used in conjunction with any of the devices shown in the above Figures, among other devices. In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired. As shown, this method may operate as follows. 
     First, in  2302  a lighting device may be provided, where the lighting device may include a first replaceable illumination module and a base module, described in detail above. For example, in one exemplary embodiment, the lighting device may comprise an embodiment of lighting system  100 , where the base module includes heat sink  44 , as well as means for electrically connecting the first replaceable illumination module to a power source, e.g., a light socket or lighting fixture. 
     In  2304 , the first replaceable illumination module may be removed from the lighting device. For example, a user may detach the first replaceable illumination module from the base module, leaving the base module in situ, or may remove the lighting device, including the first replaceable illumination module and the base module, from the light socket or lighting fixture, then detach the first replaceable illumination module from the base module. 
     In  2306 , a second replaceable illumination module may be installed in the lighting device, including attaching the second replaceable illumination module to the base module. If the base module were not removed in  2304 , then the user may attach the second replaceable illumination module to the base module while the base module remains installed in the light socket or lighting fixture. Alternatively, if the base module were removed in  2304 , then the user may attach the second replaceable illumination module to the base module, then re-install the entire assembly (second replaceable illumination module and base module) in the light socket or lighting fixture. Once the second replaceable illumination module (and base module) are properly installed, the lighting device may be configured to provide illumination using the second replaceable illumination module. 
     Note that the first replaceable illumination module and/or the second replaceable illumination module may be a replaceable illumination module  10 , as described in detail above. 
     In some embodiments, the lighting device that may include a first replaceable illumination module and a base module coupled to the first replaceable illumination module, where the base module includes heat sink  44 , and where the base module may include base connector  24  for coupling to the lighting socket. 
     As described above, in some embodiments, a method for use of replaceable illumination module  10  is described in the present technique. In certain embodiments, the method may include providing a lighting device in a lighting socket, removing the first replaceable illumination module, where the base module remains connected to the lighting socket after removing, and connecting a second replaceable illumination module to the base module after removing. In certain embodiments, the lighting device may include a first replaceable illumination module and a base module coupled to the first replaceable illumination module, where the base module may include heat sink  44 , where the base module may include base connector  24  for coupling to the lighting socket. In some embodiments, after connecting the second replaceable illumination module to the base module, the lighting device may be configured to provide illumination using the second replaceable illumination module. 
       FIG. 24  illustrates one embodiment of a method of operating a lighting system, e.g., lighting system  100 . In various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired. As shown, this method may operate as follows. 
     In  2402 , power may be received to an electrical connector of a replaceable illumination module from an external power source. For example, the replaceable illumination module may be replaceable illumination module  10 , and the electrical connector may be electrical connector  42 , both of which may be included in a lighting system  100 , embodiments of which are described above in detail. 
     In  2404 , power may be provided to a printed circuit board, e.g., printed circuit board  18 , of the replaceable illumination module via the electrical connector. 
     In  2406  power may be provided via printed circuit board to one or more solid state lighting elements  14  of the replaceable illumination module, e.g., to one or more LEDs. 
     In  2408 , light may be emitted via the one or more solid state lighting elements  14 . 
     In  2410 , at least a portion of the emitted light from one or more solid state lighting elements  14  may be transformed via one or more beam conditioning optical elements, such as beam conditioning optical elements  32 , which may be included in the replaceable illumination module. 
     Finally, in  2412 , heat may be conducted from the one or more solid state lighting elements to a heat sink, such as heat sink  44 . In one embodiment, the heat may be conducted via an interface surface of a thermal spreading element  16 , as described above in detail. Thus, in some embodiments, printed circuit board  18  may connect to one or more solid state lighting elements  14  of replaceable illumination module  10 , and may further include or be connected to thermal spreading element  16 , where thermal spreading element  16  may include the interface surface for thermally connecting to a heat sink. 
       FIG. 25  is a flowchart diagram of a method for operating a controllable lighting system, according to one embodiment. As with the above methods, in various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired. As shown, this method may operate as follows. 
     As  FIG. 25  indicates, in  2502  a controllable lighting system may be provided. The controllable lighting system may include replaceable illumination module  10 , one or more sensors coupled to or included in the replaceable illumination module  10 , and control circuitry coupled to or included in replaceable illumination module  10 . Various embodiments of the replaceable illumination module  10  are described above in detail. 
     In  2504 , one or more attributes of replaceable illumination module  10  or its environment may be monitored via the one or more sensors and the control circuitry to determine a status of the controllable lighting system. 
     In  2506 , the controllable lighting system may be regulated, or a system coupled to the controllable lighting system may be controlled, based on the determined status. As described above in detail, in various embodiments, the controllable lighting system may be a standalone device that utilizes the sensors and control circuitry to control itself, or may be communicatively coupled (possibly wirelessly) to or included in a larger system, such as an automated control network, where, for example, the controllable lighting system may communicate status information to an automated controller on the network, and the automated controller may control the controllable lighting system accordingly. In other words, the method may include sending the determined status to a controller of the automated control network and receiving signals from the controller of the automated control network, where regulating is performed in response to the signals. 
     Alternatively, or additionally, the controllable lighting system may detect a condition or determine a status of the lighting system or its environment via the one or more sensors, and may report the condition or status to a controller, which may then control some other system, e.g., a security system, based on the reported condition or status. Various embodiments of a controllable lighting system and its uses are described in detail above with reference to  FIGS. 20-22 . Of course, these are but exemplary embodiments of the method, and are not intended to limit the use or implementation of the controllable lighting system to any particular form, function, or use. 
       FIG. 26  is a flowchart diagram of a method for beam conditioning in a lighting system, according to one embodiment. As with the above methods, in various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired. As shown, this method may operate as follows. 
     In  2602 , power may be provided to a lighting system. The lighting system may include one or more solid state lighting elements  14 , e.g., LEDs, a printed circuit board, such as printed circuit board  18 , and one or more beam conditioning optical elements, such as beam conditioning optical elements  32 , various embodiments of which are described above in detail. For example, the one or more beam conditioning optical elements may include one or more of: a phosphor material, a nanophotonic material, a crystalline photonic material, an optical fiber material, a photonic crystal fiber material, an engineered microstructure material, or a dielectric waveguide material, among others. In some embodiments, the lighting system may be an embodiment of lighting system  100 , described in detail above. 
     In  2604 , light from the one or more solid state lighting elements may be spectrally transformed via at least one of the beam conditioning optical elements. More specifically, the beam conditioning optical element(s) may absorb photons with a first spectral distribution (from the one or more solid state lighting elements), and emit photons with a second spectral distribution, e.g., per some specified or desired attributes of the illumination. 
     As discussed above, in some embodiments, one or more beam conditioning optical elements  32  may be proximate to one or more solid state lighting elements  14  for generating a specified beam. Moreover, in some embodiments, the one or more beam conditioning optical elements  32  may include one or more beam forming elements configured to modify a spatial intensity distribution of the photons of the second spectral distribution for control of beam concentration or beam divergence. Examples of such beam forming elements include reflective optical elements, e.g., parabolic reflectors for light collection and directional beam output, diffractive optical elements, e.g., Fresnel lenses, or refractive elements, e.g., prism structures that use total internal reflectance to control and minimize beam divergence. Note that these particular elements are meant to be exemplary only, and are not intended to limit the beam conditioning optical elements to any particular devices or functionalities. 
     As discussed above in detail, sensors and control circuitry may be used to monitor spectral distribution or intensity distribution of spectrally transformed light from one or more solid state lighting elements  14  via the one or more sensors and modify at least one of the beam conditioning optical elements  32  to control color temperature or intensity distribution of the beam. The one or more sensors may include one or more of: a photosensor, a color sensor, or a light-intensity sensor. Additionally, in some embodiments, the control circuitry may be configured to couple to an automated control network for regulation of color output or light-intensity output of the lighting system by the automated control network. As another exemplary use, and as described above, the one or more solid state lighting elements  14  may include at least two different types of solid state lighting elements  14 , each with a respective specified spectral output. At least one of the beam conditioning optical elements  32  may be configured to homogenize light output from the solid state lighting elements  14 . 
     Manufacturing 
     As indicated above, in some embodiments, heat sink  44  may be a work piece formed by a novel method of manufacturing. 
       FIG. 27  flowcharts one embodiment of a method for manufacturing a work utilizing a dynamically controllable extrusion die. As with the above methods, in various embodiments, some of the method elements shown may be performed concurrently, in a different order than shown, or may be omitted. Additional method elements may also be performed as desired. As shown, this method may operate as follows. 
     In  2702  an extrusion die may be provided that may be controllable to dynamically vary one or more cross sectional attributes of the work piece. In other words, while prior art extrusion dies generally produce work pieces with constant cross-sectional attributes, such as cross-sectional radii or proportions, orientation, etc., whereas the present extrusion die may be operable to vary one or more of these attributes during the extrusion process. 
     In  2704 , a material may be extruded via the extrusion die to generate the work piece. The extruding may include dynamically controlling the extrusion die to vary at least one cross sectional attribute of the work piece during extruding. Thus, the generated work piece may have a variable longitudinal profile in accordance with the dynamically controlling the extrusion die. 
     For example, in one embodiment, the dynamically controllable extrusion die may be included in a dynamically controllable extrusion die system, which may include a controller and the extrusion die coupled to the controller, which may be configured to dynamically control the extrusion die to generate the work piece. For example, to dynamically control the extrusion die, the controller may be configured to send control signals to modify the extrusion die to vary one or more cross sectional attributes of the work piece during extrusion. The extrusion die may be configured to receive the control signals and vary the one or more cross sectional attributes of the work piece during extrusion in accordance with the control signals, thereby imparting a variable longitudinal profile to the work piece. Note that the sending control signals may be performed one or more times in an iterative manner to dynamically control the extrusion process. In one embodiment, sensors may be employed in or near the die to provide feedback to the controller regarding the state of the die, the extrusion, and/or the immediate environment, thereby allowing the controller to modify the commands sent to the die dynamically, e.g., “on the fly”. 
       FIG. 9 , described above, illustrates an exemplary work piece with a varying longitudinal cross-section. In some embodiments, dynamically controlling the extrusion die may include varying a cross section of the extrusion die to taper the work piece, thereby generating a tapered work piece, as shown in  FIG. 9 . Thus, in some embodiments, the at least one extrusion may include a tapered extrusion. In some embodiments, the work piece may be or include heat sink  44 , which may include at least one extrusion, which, as noted above, may include a plurality of heat fins  46  (see, e.g.,  FIGS. 7 and 8 ). Details regarding properties of the heat sink  44  are presented above. 
     The extrusion die may be controllable to implement a variable constriction, and so may be used to form a shaped heat sink, e.g., a tapered heat sink with a decreasing diameter along the extrusion axis. In certain embodiments, the shaped heat sink may include both functional form factor aspects and desirable aesthetics. 
     Dynamically controlling the extrusion die may include rotating the extrusion die during extrusion to impart a twist to the work piece.  FIG. 10 , described above in detail, illustrates an exemplary work piece that is both tapered and twisted. Note that twisting the extrusion (along a predetermined heat sink axis) may increase heat fin  46  surface area in a given volume, and thus may improve or even optimize heat transfer via the heat fins  46 . In one embodiment, the twisting process may impart a bell shape, lamp shape, turnip shape, or other desired shape, to the heat sink  44 . 
     In some embodiments, the heat sink  44  may include a plurality of extrusions, e.g., a plurality of stacked extrusions, where each stacked extrusion may have a respective radius, and where the plurality of stacked extrusions may be ordered in accordance with their respective radii to form a stepwise tapered heat sink  44 . In certain embodiments, the heat fins  46  of at least one of the plurality of stacked extrusion may not be aligned with corresponding heat fins  46  of at least one adjacent stacked extrusion. In various embodiments, the stacked extrusions may produced separately and bonded or otherwise connected together, or, alternatively, may be formed sequentially, e.g., with step-wise modification of the radii at the junctures between the extrusions. The method for manufacturing a work piece may also include thermally modifying the material during the extruding, e.g., heating the extrusion die. 
     In one embodiment, program instructions implementing the above dynamic control of the extrusion die may be stored on a non-transitory memory medium. The program instructions may be stored on the controller, and executed by a processor of the controller to perform embodiments of the above method of manufacture. 
     Additional steps or techniques may also be used to generate the work piece (e.g., heat sink). For example, the method may include utilizing a forming wheel to modify each of the plurality of heat fins  46 . In certain embodiments, the method for manufacturing a work piece may include applying a braising paste or a furnace bake to the generated work piece. As another example, after the above extruding, the method may further include thermally heating the work piece and/or compressing the work piece into a mold or a forming structure. For example, compressing the work piece may include forming one or more tapers or notches. In some embodiments, the heat fins  46  may be formed via a thermo-mechanical forming process that may reshape an existing extrusion using a negative form of the desired shape, e.g., a mold. Additionally, or alternatively, the work piece may be rotated into a mold or a forming structure. In various embodiments, the forming structure may be fixed, or may be articulated. In further embodiments, forming the heat sink  44  may include post processing of the cut extrusions. 
     Thus, the heat sink  44 , and heat fins  46  specifically, may be shaped and modified during extrusion and/or in a post extrusion process. In other words, the tapered extrusion(s) of heat sink  44  may be formed at least in part via the dynamically controlled extrusion process disclosed above. In certain embodiments, modification of the extrusion shape of the heat sink  44  may conform to ANSI form factors. Moreover, modification of the extrusion shape of heat sink  44  as described herein may achieve sufficient surface area of the heat sink  44  for highly effective heat transfer from the solid state lighting elements  14  of lighting system  100 . 
     For example, the heat sink  44  may be an extruded heat sink with a reduced void density that may be achievable by the extrusion process, resulting in superior heat conduction over cast heat sinks. In some embodiments, the particular extrusion alloy used may be selected based on a combination of extrusion performance and thermal conductivity parameters. For example, in some embodiments, heat sink  44  may be made of an aluminum material, e.g., aluminum or an aluminum compound or alloy. 
     Assembly 
     In some embodiments, the manufacture and assembly of heat sink  44  with replaceable illumination module  10  may include modular design and modular fabrication methods. For example, the manufacture and assembly of heat sink  44  with replaceable illumination module  10  may minimize parts count and control cost. In some embodiments, joining methods to join heat sink  44  to shaft and base connector assembly  50  may optimize heat transfer between modular components and provide sufficient thermal management to maintain proper operation of the lighting system. 
     In one embodiment, heat sink  44  may be frictionally interfaced to replaceable illumination module  10 , thereby creating a thermal bond. In other exemplary embodiments, heat sink  44  may be thermally bonded with a fastening method to replaceable illumination module  10  to provide an interface with a predetermined separation distance, which may be less than 5×10 −5  meters. For example, a press fit may minimize contact gaps and consequently reduce thermal conductivity resistance. 
     In further embodiments, joining methods, such as braising paste and furnace bake, may form a continuous interface between heat sink  44  and replaceable illumination module  10  to promote thermal transport. Additionally, or alternatively, heat transfer potting compounds and thermally conductive pads may join heat sink  44  with replaceable illumination module  10 . 
     The features and functions described herein provide for various embodiments of a novel and useful lighting system. Although various embodiments which incorporate the teachings of the present disclosure have been shown and described in detail herein, those skilled in the art may readily devise many other varied embodiments that still incorporate these teachings. The foregoing description of the preferred embodiments, therefore, is provided to enable any person skilled in the art to make or use the claimed subject matter. 
     The generic principles defined herein may be applied to other embodiments without the use of the innovative faculty. Thus, the claimed subject matter is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 
     Reference in the specification to “one embodiment”, “an embodiment”, “some embodiments”, or “certain embodiments”, means that a particular feature, structure, characteristics, or method described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of “one embodiment”, “an embodiment”, “some embodiments”, or “certain embodiments” are not necessarily all referring to the same embodiments. 
     Reference in the specification to “approximately” means within a specified tolerance, which in various embodiments may be, for example, within ten percent, within five percent, or within one percent, and so forth, depending on the application. 
     Furthermore, note that the word “may” is used throughout this application in a permissive sense (e.g., having the potential to, being able to), not a mandatory sense (e.g., must). The term “include”, and derivations thereof, mean “including, but not limited to”. As used in this specification, the singular forms “a”, “an” and “the” include plural referents unless the content clearly indicates otherwise. Thus, for example, reference to “a device” includes a combination of two or more devices. The term “coupled” means “directly or indirectly connected”. The term “or” as used herein is intended to be inclusive unless otherwise indicated. 
     All references cited herein, including publications, patent applications, and patents, are hereby incorporated by reference as though fully and completely set forth herein. 
     Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. The specification and examples above are exemplary only, with the true scope of the present invention being determined by the following claims.