WO2016092405A1

WO2016092405A1 - Color-adjustable luminaire with consistent intensity

Info

Publication number: WO2016092405A1
Application number: PCT/IB2015/059168
Authority: WO
Inventors: Solomon Raju CHINNAM
Original assignee: Philips Lighting Holding B.V.
Priority date: 2014-12-09
Filing date: 2015-11-27
Publication date: 2016-06-16

Abstract

A system such as a luminaire (100, 200, 300, 500) configured with selected aspects of the present disclosure includes one or more light- emitting diode ("LED") drivers (210, 310, 510) having one or more dimming interfaces (312, 512). One or more strings of LEDs (106, 206, 306, 506) are operably coupled with one or more outputs of the one or more LED drivers. A user interface element (108) may be provided, e.g., in a manner such that it is accessible from an exterior of a luminaire. A variable resistance assembly (218, 318, 418, 518) is operably coupled with the one or more dimming interfaces, and may include a plurality of potential configurations in which the variable resistance assembly applies one or more respective predetermined resistances to the one or more dimming interfaces. The user interface element may be physically actuated between a plurality of positions that correspond to the potential configurations of the variable resistance assembly.

Description

COLOR-ADJUSTABLE LUMINAIRE WITH CONSISTENT INTENSITY

Cross Reference to Related Applications

[0001] The present invention claims priority to U .S. Provisional Patent Application Serial No. 62/089,649, entitled "COLOR ADJ USTABLE HI POWER LED LUMINAIRE" and filed on December 9, 2014, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

[0002] The present invention is directed generally to lighting control . More particularly, various inventive methods and apparatus disclosed herein relate to luminaires that are adjustable to emit light of different correlated color temperatures ("CCT") with consistent intensity.

Background

[0003] Digital lighting technologies, i.e., il lumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offer a viable alternative to traditional fluorescent, HID, and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent advances in LED technology have provided efficient and robust ful l-spectrum lighting sources that enable a variety of lighting effects in many applications. Some of the fixtures embodying these sources feature a lighting module, including one or more LEDs capable of producing different colors, e.g., red, green, and blue, as well as a processor for independently controlling the output of the LEDs in order to generate a variety of colors and color-changing lighting effects, for example, as discussed in detail in U .S. Patent Nos. 6,016,038 and 6,211,626, incorporated herein by reference.

[0004] Existing luminaires may be capable of being "tuned" to emit various colors, such as variations of white having different CCTs. Some such luminaires may arrange one or more light sources (such as LEDs) in a color mixing chamber, and/or may have phosphor applied to the one or more light sources in order to achieve particular CCTs. Control systems associated with such luminaires may be relatively complex and/or expensive because they are often implemented using microcontrol lers and/or integrated circuits ("IC"). They may also include open or closed feedback loops in order to achieve CCT consistency. However, while CCT consistency may be achieved, there may be loss of output lumens across CCTs. Moreover, to adjust such luminaires, it is often required to open up a case or housing to access a driver compartment. Thus, adjusting CCT is cumbersome and not user friendly. Thus, there is a need in the art for a simple, cost-effective CCT adjustment solution for luminaires.

Summary

[0005] The present disclosure is directed to inventive methods and apparatus for luminaires that are adjustable to emit light of different correlated color temperatures ("CCT") while maintaining relatively consistent intensity. In various embodiments, a luminaire may include one or more strings of LEDs operably coupled with one or more LED drivers. The luminaire may be equipped with various mechanisms for applying variable resistance (e.g., in discrete steps or continuously) to one or more dimming interfaces of the one or more LED drivers. Each of the one or more LED drivers may map (e.g., in a lookup table) each level of applied resistance to a different current output to be provided to a respective string of LEDs. Thus, each level of resistance applied by the variable resistance assembly maps to a different set of current outputs to be provided to the strings of LEDs. Each set of current outputs may be selected to cause the strings of LEDs to collectively emit light having particular CCT while maintaining relatively consistent intensity (i.e. lumen output) across multiple sets of current outputs.

[0006] Generally, in one aspect, a luminaire may include: a housing; an LED driver with a dimming interface contained within the housing; a string of LEDs operably coupled with an output of the LED driver; a user interface element accessible from an exterior of the housing; and a variable resistance assembly contained in the housing and operably coupled with the dimming interface. The variable resistance assembly may include a plurality of potential configurations in which the variable resistance assembly applies a predetermined resistance to the dimming interface. The variable resistance assembly may be toggled between its potential configurations in response to physical actuation of the mechanical user interface element. I n response to each resistance applied by the variable resistance assembly in each respective potential configuration of the variable resistance assembly, the LED driver may provide current in a different manner to the string of LEDs.

[0007] In various embodiments, the variable resistance assembly includes a bank of resistors. In various embodiments, the variable resistance assembly includes a potentiometer. In various embodiments, each of the predetermined resistances provided by the variable resistance assembly may be selected to cause the string of LEDs to emit light having a different CCT. In various embodiments, the variable resistance assembly may include a switch mechanically coupled with the user interface element. In various versions, physical actuation of the user interface element may cause the switch to transition from electrically coupling a first set of one or more resistors of the variable resistance assembly with the dimming interface to electrically coupling a second set of one or more resistors of the variable resistance assembly with the dimming interface. In various versions, the switch may be a dual pole switch or dual rail step switch.

[0008] In various embodiments, the LED driver may provide a pulse width modulated current to the string of LEDs in response to resistance applied by the variable resistance assembly in at least one potential configuration of the variable resistance assembly. In various embodiments, the string of LEDs may include a first string of LEDs operably coupled with a first output of the LED driver, and the luminaire further comprises a second string of LEDs. In various versions, the second string of LEDs may be operably coupled with a second output of the LED driver. In response to each resistance applied by the variable resistance assembly in each potential configuration of the variable resistance assembly, the LED driver may provide current in a different manner to the second string of LEDs. In various versions, the second string of LEDs may be operably coupled with an output of a second LED driver. A dimming interface of the second LED driver may be operably coupled with the variable resistance assembly. In response to each resistance applied by the variable resistance assembly in each potential configuration of the variable resistance assembly, the second LED driver may provide current in a different manner to the second string of LEDs. [0009] As used herein for purposes of the present disclosure, the term "LED" should be understood to include any electroluminescent diode or other type of carrier injection/junction- based system that is capable of generating radiation in response to an electric signal. Thus, the term LED includes, but is not limited to, various semiconductor-based structures that emit light in response to current, light emitting polymers, organic light emitting diodes (OLEDs), electroluminescent strips, and the like. In particular, the term LED refers to light emitting diodes of all types (including semi-conductor and organic light emitting diodes) that may be configured to generate radiation in one or more of the infrared spectrum, ultraviolet spectrum, and various portions of the visible spectrum (generally including radiation wavelengths from approximately 400 nanometers to approximately 700 nanometers). Some examples of LEDs include, but are not limited to, various types of infrared LEDs, ultraviolet LEDs, red LEDs, blue LEDs, green LEDs, yellow LEDs, amber LEDs, orange LEDs, and white LEDs (discussed further below). It also should be appreciated that LEDs may be configured and/or controlled to generate radiation having various bandwidths (e.g., full widths at half maximum, or FWHM) for a given spectrum (e.g., narrow bandwidth, broad bandwidth), and a variety of dominant wavelengths within a given general color categorization.

[0010] For example, one implementation of an LED configured to generate essentially white light (e.g., a white LED) may include a number of dies which respectively emit different spectra of electroluminescence that, in combination, mix to form essentially white light. In another implementation, a white light LED may be associated with a phosphor material that converts electroluminescence having a first spectrum to a different second spectrum. In one example of this implementation, electroluminescence having a relatively short wavelength and narrow bandwidth spectrum "pumps" the phosphor material, which in turn radiates longer wavelength radiation having a somewhat broader spectrum.

[0011] It should also be understood that the term LED does not limit the physical and/or electrical package type of an LED. For example, as discussed above, an LED may refer to a single light emitting device having multiple dies that are configured to respectively emit different spectra of radiation (e.g., that may or may not be individually controllable). Also, an LED may be associated with a phosphor that is considered as an integral part of the LED (e.g., some types of white LEDs). In general, the term LED may refer to packaged LEDs, non-packaged LEDs, surface mount LEDs, chip-on-board LEDs, T-package mount LEDs, radial package LEDs, power package LEDs, LEDs including some type of encasement and/or optical element (e.g., a diffusing lens), etc.

[0012] The term "light source" should be understood to refer to any one or more of a variety of radiation sources, including, but not limited to, LED-based sources (including one or more LEDs as defined above), incandescent sources (e.g., filament lamps, halogen lamps), fluorescent sources, phosphorescent sources, high-intensity discharge sources (e.g., sodium vapor, mercury vapor, and metal halide lamps), lasers, other types of electroluminescent sources, pyro-luminescent sources (e.g., flames), candle-luminescent sources (e.g., gas mantles, carbon arc radiation sources), photo-luminescent sources (e.g., gaseous discharge sources), cathode luminescent sources using electronic satiation, galvano-luminescent sources, crystallo- luminescent sources, kine-luminescent sources, thermo-luminescent sources, triboluminescent sources, sonoluminescent sources, radioluminescent sources, and luminescent polymers.

[0013] A given light source may be configured to generate electromagnetic radiation within the visible spectrum, outside the visible spectrum, or a combination of both. Hence, the terms "light" and "radiation" are used interchangeably herein. Additionally, a light source may include as an integral component one or more filters (e.g., color filters), lenses, or other optical components. Also, it should be understood that light sources may be configured for a variety of applications, including, but not limited to, indication, display, and/or illumination. An

"illumination source" is a light source that is particularly configured to generate radiation having a sufficient intensity to effectively illuminate an interior or exterior space. In this context, "sufficient intensity" refers to sufficient radiant power in the visible spectrum generated in the space or environment (the unit "lumens" often is employed to represent the total light output from a light source in all directions, in terms of radiant power or "luminous flux") to provide ambient illumination (i.e., light that may be perceived indirectly and that may be, for example, reflected off of one or more of a variety of intervening surfaces before being perceived in whole or in part). [0014] The term "spectrum" should be understood to refer to any one or more frequencies (or wavelengths) of radiation produced by one or more light sources. Accordingly, the term "spectrum" refers to frequencies (or wavelengths) not only in the visible range, but also frequencies (or wavelengths) in the infrared, ultraviolet, and other areas of the overall electromagnetic spectrum. Also, a given spectrum may have a relatively narrow bandwidth (e.g., a FWHM having essentially few frequency or wavelength components) or a relatively wide bandwidth (several frequency or wavelength components having various relative strengths). It should also be appreciated that a given spectrum may be the result of a mixing of two or more other spectra (e.g., mixing radiation respectively emitted from multiple light sources).

[0015] For purposes of this disclosure, the term "color" is used interchangeably with the term "spectrum." However, the term "color" generally is used to refer primarily to a property of radiation that is perceivable by an observer (although this usage is not intended to limit the scope of this term). Accordingly, the terms "different colors" implicitly refer to multiple spectra having different wavelength components and/or bandwidths. It also should be appreciated that the term "color" may be used in connection with both white and non-white light.

[0016] The terms "color temperature," "correlated color temperature," and "CCT" generally are used herein in connection with white light, although this usage is not intended to limit the scope of these terms. Color temperature essentially refers to a particular color content or shade (e.g., reddish, bluish) of white light. The color temperature of a given radiation sample conventionally is characterized according to the temperature in degrees Kelvin (K) of a black body radiator that radiates essentially the same spectrum as the radiation sample in question. Black body radiator color temperatures generally fall within a range of approximately 700 degrees K (typically considered the first visible to the human eye) to over 10,000 degrees K; white light generally is perceived at color temperatures above 1,500-2000 degrees K.

[0017] Lower color temperatures generally indicate white light having a more significant red component or a "warmer feel," while higher color temperatures generally indicate white light having a more significant blue component or a "cooler feel." By way of example, fire has a color temperature of approximately 1,800 degrees K, a conventional incandescent bulb has a color temperature of approximately 2848 degrees K, early morning daylight has a color temperature of approximately 3,000 degrees K, and overcast midday skies have a color temperature of approximately 10,000 degrees K. A color image viewed under white light having a color temperature of approximately 3,000 degree K has a relatively reddish tone, whereas the same color image viewed under white light having a color temperature of approximately 10,000 degrees K has a relatively bluish tone.

[0018] The terms "lighting fixture" or "luminaire" are used herein to refer to an

implementation or arrangement of one or more lighting units in a particular form factor, assembly, or package. The term "lighting unit" is used herein to refer to an apparatus including one or more light sources of same or different types ("lighting unit" will be used predominantly herein). A given lighting unit may have any one of a variety of mounting arrangements for the light source(s), enclosure/housing arrangements and shapes, and/or electrical and mechanical connection configurations. Additionally, a given lighting unit optionally may be associated with (e.g., include, be coupled to and/or packaged together with) various other components (e.g., control circuitry) relating to the operation of the light source(s). An "LED-based lighting unit" refers to a lighting unit that includes one or more LED-based light sources as discussed above, alone or in combination with other non LED-based light sources. A "multi-channel" lighting unit refers to an LED-based or non LED-based lighting unit that includes at least two light sources configured to respectively generate different spectrums of radiation, wherein each different source spectrum may be referred to as a "channel" of the multi-channel lighting unit.

[0019] The term "controller" is used herein generally to describe various apparatus relating to the operation of one or more light sources. A controller can be implemented in numerous ways (e.g., such as with dedicated hardware) to perform various functions discussed herein. A "processor" is one example of a controller which employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform various functions discussed herein. A controller may be implemented with or without employing a processor, and also may be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0020] In various implementations, a processor or controller may be associated with one or more storage media (generically referred to herein as "memory," e.g., volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, floppy disks, compact disks, optical disks, magnetic tape, etc.). In some implementations, the storage media may be encoded with one or more programs that, when executed on one or more processors and/or controllers, perform at least some of the functions discussed herein. Various storage media may be fixed within a processor or controller or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller so as to implement various aspects of the present invention discussed herein. The terms "program" or "computer program" are used herein in a generic sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program one or more processors or controllers.

[0021] The term "addressable" is used herein to refer to a device (e.g., a light source in general, a lighting unit or fixture, a controller or processor associated with one or more light sources or lighting units, other non-lighting related devices, etc.) that is configured to receive information (e.g., data) intended for multiple devices, including itself, and to selectively respond to particular information intended for it. The term "addressable" often is used in connection with a networked environment (or a "network," discussed further below), in which multiple devices are coupled together via some communications medium or media.

[0022] In one network implementation, one or more devices coupled to a network may serve as a controller for one or more other devices coupled to the network (e.g., in a master/slave relationship). In another implementation, a networked environment may include one or more dedicated controllers that are configured to control one or more of the devices coupled to the network. Generally, multiple devices coupled to the network each may have access to data that is present on the communications medium or media; however, a given device may be "addressable" in that it is configured to selectively exchange data with (i.e., receive data from and/or transmit data to) the network, based, for example, on one or more particular identifiers (e.g., "addresses") assigned to it.

[0023] The term "network" as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (e.g., for device control, data storage, data exchange, etc.) between any two or more devices and/or among multiple devices coupled to the network. As should be readily appreciated, various implementations of networks suitable for interconnecting multiple devices may include any of a variety of network topologies and employ any of a variety of communication protocols.

Additionally, in various networks according to the present disclosure, any one connection between two devices may represent a dedicated connection between the two systems, or alternatively a non-dedicated connection. In addition to carrying information intended for the two devices, such a non-dedicated connection may carry information not necessarily intended for either of the two devices (e.g., an open network connection). Furthermore, it should be readily appreciated that various networks of devices as discussed herein may employ one or more wireless, wire/cable, and/or fiber optic links to facilitate information transport throughout the network.

[0024] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.

Brief Description of the Drawings

[0025] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [0026] Fig. 1 illustrates an example luminaire configured with selected aspects of the present disclosure.

[0027] Fig. 2 depicts schematically how multiple strings of LEDs may be selectively driven based on variable resistance applied to LED drivers, in accordance with various embodiments.

[0028] Fig. 3 schematically depicts an example electrical circuit arrangement configured with selected aspects of the present disclosure, in accordance with various embodiments.

[0029] Fig. 4 schematically depicts another example variable resistance assembly, in accordance with various embodiments.

[0030] Fig. 5 schematically depicts another example electrical circuit arrangement configured with selected aspects of the present disclosure, in accordance with various embodiments.

[0031] Fig. 6 depicts an example method of assembling a luminaire configured with selected aspects of the present disclosure, in accordance with various embodiments.

Detailed Description

[0032] Existing luminaires may be capable of being "tuned" to emit various colors, such as variations of white having different CCTs. Some such luminaires may arrange one or more light sources (such as LEDs) in a color mixing chamber, and/or may include phosphor applied to the one or more light sources in order to achieve particular CCTs. Control systems associated with such luminaires may be relatively complex and/or expensive because they are often implemented using microcontrollers and/or integrated circuits ("IC"). They may also include open or closed feedback loops in order to achieve CCT consistency. However, while CCT consistency may be achieved, there may be loss of output lumens across CCTs. Moreover, to adjust such luminaires, it is often required to open up a case or housing to access a driver compartment, making adjusting CCT cumbersome and not user friendly. Thus, there is a need in the art for a simple, cost-effective, and user friendly CCT adjustment solution for luminaires to emit light having relatively consistent intensity across multiple CCTs. In view of the foregoing, various embodiments and implementations of the present invention are directed to luminaires that are easily adjustable to emit light having consistent intensity across multiple CCTs.

[0033] Referring to Fig. 1, in one embodiment, a luminaire 100 may include a housing 102, a mount 104, and one or more strings of LEDs 106a-b. In this example, luminaire 100 is an LED- based floodlight that may be planted into a surface such as the ground using mount 104.

However, this is not meant to be limiting, and a variety of other form factors are possible. Also, in this example, there are two strings of LEDs, 106a and 106b, each with sixteen individual LEDs. However, this is not meant to be limiting. In other embodiments, each string 106 of LEDs may include more or less than sixteen individual LEDs, and different strings may include different numbers of LEDs. Moreover, luminaire 100 may include more or less than two strings of LEDs.

[0034] In various embodiments, luminaire 100 may be transitioned between a plurality of preset configurations in which strings of LEDs 106a-b collectively emit light having various desired CCTs, and yet with relatively constant intensity across CCTs. For example, luminaire 100 may be used as a floodlight to illuminate an exterior of a building. In various embodiments, luminaire 100 may be manually adjusted to emit white light at various stepped CCT intervals between approximately 3,000 degrees K and approximately 5,700 degrees K. This enables luminaire 100 to illuminate the building with various degrees of warmth.

[0035] In some implementations, luminaire 100 may be manually adjusted between multiple configurations, and in each configuration, strings of LEDs 106a-b may collectively emit light at a particular CCT. For example, in one embodiment, luminaire 100 may be toggled between the following configurations: a first at which luminaire 100 emits light at 3,000 degrees K; a second at which luminaire 100 emits light at 3,500 degrees K; a third at which luminaire 100 emits light at 4,000 degrees K; a fourth at which luminaire 100 emits light at 4,500 degrees K; a fifth at which luminaire 100 emits light at 5,000 degrees K; and a sixth at which luminaire 100 emits light at 5,500 degrees K. The lumen output across all CCT configurations may, however, remain relatively consistent. Of course, this is just one example, and numerous other CCTs and step intervals between CCTs may be employed instead, depending on the circumstances. [0036] Each stri ng of LEDs 106 may be selected to emit light havi ng particu lar characteristics. For exa mple, LEDs on first string 106a may be selected from a first LED bin and/or may be selected based on havi ng a particular flux. Similarly, LEDs on second string 106b may be selected from a second LED bin and/or may be selected based on having a particular fl ux. I n this manner, light emitted by one string 106 i n isolation may have a different CCT than light emitted by another string i n isolation. However, when the light emitted by the two strings is com bi ned, it may have a different CCT than either string alone. This com bi ned or col lective CCT is what may be perceived by a passerby. Accordi ngly, in order to adjust the CCT of combined light emitted by multiple stri ngs of LEDs (while maintaining relatively constant intensity), each individua l string 106 may be powered with cu rrent i n a different amou nt or manner. How current is applied to each string individual ly to achieve a desired combined CCT may be determi ned at the factory, and wil l be described below.

[0037] Lumi naire 100 may be toggled between preset configu rations in various ways. I n some em bodiments, a user interface element 108 may be physical ly actuated between multiple positions in order to toggle lu minaire 100 between mu lti ple present configu rations. For example, in Fig. 1, user interface element 108 is a screw that may be actuated by inserted a screwdriver (flat head in this exam ple) and rotating the screwdriver to rotate the screw between multiple potential positions as shown by the arrow. Each potential position of the screw may correspond to one of the plurality of preset configurations of l umi naire 100, and thus may correspond to a desired CCT output. As wil l be explained below, user interface element 108 may be coupled with various mechanisms that are configu red to vary a resistance applied to one or more LED drivers. By varying resistance applied to one or more LED drivers, a set of cu rrent outputs necessary to achieve a particular com bined CCT may be provided to the stri ngs 106a-b.

[0038] While user interface element 108 is depicted as a flat head screw on the front of housing 102 in Fig. 1, this is not mea nt to be li miting. Various other mechanisms may be employed, and may be employed at various other locations of housing 102. For exam ple, in various embodiments, various other types of screws, such as Phil lips, hex (e.g., Al len), fluted, and so forth, may be em ployed instead . I n other em bodi ments, other physical actuators may be employed, such as knobs, dials, nuts, bolts, sliders, and so forth. I n addition, a physical actuator may be instal led at any location on housing 102, such as on top, bottom, on a side, on a back, on mount 104, and so forth. I n various embodiments, the physical actuator employed as user interface element 108 may be readily accessible from the outside of housing 102, so that it can be easily actuated by a technician. In some embodiments, such as that depicted in Fig. 1, a tool such as a screw driver or Allen wrench may be required to actuate user interface element 108, which may prevent or at least dissuade u nauthorized persons from attempting to adjust light output by luminaire 100.

[0039] Fig. 2 and Table 1 below demonstrate how light emitted by individual strings of LEDs may be adjusted in response to changes in resistance applied by a variable resistance assembly, in order to achieve a combined light output having a desired CCT at each discrete step. In Fig. 2, a luminaire 200 is schematical ly depicted that is similar to luminaire 100, except there are four strings of LEDs 206a-d, rather than two. Two LED drivers 210a-b are operably coupled variously with the four strings of LEDs 206a-d in order to drive the strings of LEDs 106a-d with various currents. For this example, assume first and third strings of LEDs, 206a and 206c, are selected (e.g., LED bins/flux selected) to emit light with a measured CCT of 3,000 degrees K, and that second and fourth strings of LEDs, 206b and 206d, are selected to emit light with a measured CCT of 5,700 degrees K. Table 1, below, demonstrates how each of the strings of LEDs 206a-d may be driven with different currents to emit collective light 219 having various desired CCTs, all while maintaining relatively consistent intensity.

TABLE 1

As shown in table 1, above, when "warm" light (i.e. light having a relatively low CCT such as 3,000 degrees K) is desired, first and third strings 206a and 206c may be provided with proportionally high current (1.02 amps). Second and fourth strings 206b and 206d may be provided with proportionally low current (0.22 amps). The combined light CCT is relatively warm, at 3,000 degrees K. This may be achieved, for instance, by transitioning variable resistance assembly 218 to a particular configuration that causes it to apply a particular resistance to LED drivers 210a-b, thereby causing LED drivers to output the currents described above.

[0040] Conversely, when "cool" light (i.e. light having a relatively high CCT such as 5,500 degrees K) is desired, first and third strings 206a and 206c may be provided with proportionally low current (0.10 amps). Second and fourth strings 206b and 206d may be provided with proportionally high current (1.02 amps). The combined light CCT is relatively cool, at 5,500 degrees K. This may be achieved, for instance, by transitioning variable resistance

assembly 218 to another particular configuration that causes it to apply another particular resistance to LED drivers 210a-b, thereby causing LED drivers 210a-b to output the currents described above. [0041] Put more simply, to achieve "cool" light, the "cool" strings of LEDs (206b and 206d) may be provided proportional ly greater current, and the "warm" strings of LEDs (206a and 206d) may be provided with proportionally less current. And vice versa. And no matter the CCT achieved in the combined light emitted by all four strings 206a-d, the lumens output remains relatively steady between 11520 and 11040 lumens. Such a smal l variation may be relatively imperceptible to the human eye.

[0042] Referring now to Fig. 3, components of another example luminaire 300 configured with selected aspects of the present disclosure is presented schematically. I n this example, two strings of LEDs, 306a and 306b, are depicted. First string 306a is powered by a first LED driver 310a. Second string 306b is powered by a second LED driver 310b. As noted above, in other embodiments, more or less strings of LEDs and/or LED drivers may be employed. In this particular example, first and second LED drivers 310a-310b each has a single output (connected to a single string 306). In other embodiments, such as that depicted in Fig. 2, an LED driver may include two outputs, or "channels." Each output or channel may be operably coupled with a string of LEDs. Such "dual channel" LED drivers may be programmable, e.g., at the factory, so that each channel/output behaves the same or differently depending on the resistance applied to a dimming interface. Referring back to Fig. 3, both LED drivers 310 are dimmable, and so first LED driver 310a includes a first dimming interface 312a and second LED driver 310b includes a second dimming interface 312b.

[0043] A variable resistance assembly 318 may be electrically coupled with leads 314 of both the dimming interfaces 312a and 312b. As described previously, variable resistance assembly 318 may be operable to vary an amount of resistance (or impedance, as the case may be) that is applied to dimming interfaces 312a and 312b. For example, in Fig. 3, variable resistance assembly 318 includes a dual rail step switch 323 that is operable as indicated by the arrows to rotate one or more of two poles, 324a and 324b, so that it is electrically coupled with one of a series of leads. The number of resistors incorporated into the mini-circuit formed between each dimming interface 312 and switch 323 may dictate how much resistance is applied to each respective dimming interface 312. Thus, by toggling the poles 324a-b through the leads, variable resistance assembly applies a variable amount of resistance to dimming interfaces 312a and 312b. Of course, other types of switches may be used to apply variable resistance, such as continuous switches, digital switches, and so forth. At least one other example will be described below with respect to Fig. 4.

[0044] In various embodiments, such as that depicted in Fig. 3, the LED drivers 310 may each have a single output that provides current to strings of LEDs 306 in different ways depending on an amount of resistance applied by variable resistance assembly 318. Accordingly, the resistance (or impedance, as the case may be) applied to leads 314 by variable resistance assembly 318 may cause each LED driver 310 to provide a specific current to its output that drives a respective string 306. For example, each LED driver 310 may be programmable, e.g., using a lookup table stored in its internal memory (not depicted), to map a resistance applied by variable resistance assembly 318 to one or more parameters of output current. Parameters of output current may include an amount of current (e.g., in amps) and/or a pulse width modulation ("PWM") scheme to be applied to the output current. For example, in response to a first resistance applied by variable resistance assembly 318, an LED driver 310 may provide a particular amount of steady current to a string of LEDs 306. In response to a second resistance applied by variable resistance assembly 318, the LED driver 310 may provide a PWM current to the string of LEDs 306.

[0045] The amount of resistance applied by variable resistance assembly 318 in each of its potential configurations may be calibrated based on desired CCT and lumen output of al l strings of LEDs collectively. As noted above, in some embodiments, a series of discrete CCTs, such as discrete steps between "warm" and "cold" white light, may be targeted at each potential configuration of variable resistance assembly 318. In some embodiments, relatively stable lumen output across CCT settings may be achieved by building, e.g., at the factory, LEDs strings using various selected combinations of LEDs having particular bins, drive currents, and/or fluxes, as wel l as by selecting a particular number of LEDs to be used to build each string 306. For example, one string could be built with x LEDs associated with a first LED bin, and another string could be built with y LEDS associated with a second LED bin. Accordingly, the multiple strings 306a-b need not be of equal lengths, and in fact could be different lengths depending on the circumstances. [0046] Strings of LEDs and variable resistance assemblies in some embodiments may be selected and/or built (e.g., at the factory) as follows. Each string 106 of LEDs may be tuned to particular CCT and intensity. In some instances, strings may be tuned without using phosphor conversion (e.g., a color mixing chamber of phosphor coating) beyond the LED package. For example, a range of actual CCTs emitted by individual LEDs of a string may be sensed. Then, an amount of current that must be applied to the string of LEDs to achieve a desired (e.g., midpoint) CCT within the range of actual CCTs may be determined. Once the amount of current needed to achieve the desired CCT is known, an LED driver may be programmed to output the amount of current needed in response to a particular amount of resistance being applied to a dimming interface of the LED driver. This may be repeated for multiple strings, each having its own individual CCT, to define a series of discrete and/or continuous resistances that will map (e.g., in a lookup table stored in memory of one or more LED drivers) to a series of discrete currents and/or PWM schemes to be applied to each string of LEDs.

[0047] As noted above, in various embodiments, variable resistance assemblies such as 218 and 318 may be toggled through various discrete or continuous configurations in which they apply various amounts of resistance to LED drivers. In some embodiments, a variable resistance assembly may be toggled through its various configurations using user interface element 108. For example, user interface element 108 may be mechanically coupled (directly or indirectly, e.g., using a series of gears or other similar mechanisms) to a switch (e.g., 323) of a variable resistance assembly. Physically actuating the mechanical user interface element 108, e.g., by rotating it through various positions, may likewise operate switches to contact poles (e.g., 324) with various leads of resistor banks, which in turn may add to or subtract from resistance applied to an LED driver by the variable resistance assembly. The control circuitry depicted in Figs.2-3 (and Fig.4, below) may be enclosed in a housing of a luminaire, such as within housing 102 of luminaire 100. However, because the control circuitry (e.g., a switch) may be mechanically connected to user interface element 108, a technician is able to change adjust CCT output of a luminaire without opening up a housing, e.g., using simple tools such as screw drivers. [0048] Fig. 4 schematically depicts an alternative variable resistance assembly 418 (which could be used in of 218 and/or in place of 318) that may be operable to vary an amount of resistance applied to dimming leads 414 of LED drivers (not depicted in Fig. 4, see Figs. 2-3). Variable resistance assembly 418 includes a first bank 420a of resistors 422ai_₆ and a second bank 420b of resistors 422bi_₆. Each resistor 422a of the first bank 420a may have a different resistance selected to achieve a desired current to be applied to, for example, dimming interface 312a. Likewise, each resistor 422b of second bank 420b may have a different resistance selected to achieve a desired current to be applied to, for instance, dimming interface 312b.

[0049] One or more switches 423 may be electrically coupled with one or more dimming leads 414 of a power supply or LED driver (not depicted in Fig. 4, see Figs. 2-3). Switch 423 may be operable, e.g., by physically actuating user interface element 108, to selectively couple an individual resistor 422 of each resistor bank 420 in Fig. 4 to the respective leads 414. I n Fig. 4, switch 423 takes the form of a so-called "dual pole" switch that is rotatable so that one pole 424a contacts a resistor 422a of first resistor bank 420a and an opposite pole 424b contacts a resistor 422b of second resistor bank 420b. In various embodiments, switch 423 may be a continuous or discrete dual pole switch.

[0050] The embodiment depicted in Fig. 4 may be operated as follows. A luminaire in which variable resistance assembly 418 is instal led may be energized, e.g., by connecting the luminaire (e.g., via mount 104) to a power supply, such as mains. By default, switch 423 may be arranged, for instance, as shown in Fig. 4, with first pole 424a contacting a first resistor 422ai of first resistor bank 420a, and with second pole 424b contacting a sixth resistor 422b₆ of second resistor bank 420b. A technician may insert a screwdriver into user interface element 108 and rotate the screw driver to a next potential position. This may cause switch 423 to rotate in the direction shown by the arrows in Fig. 4 so that first pole 424a contacts a second resistor 422a₂ of first resistor bank 420a and second pole 424b contacts a fifth resistor 422b₅ of second resistor bank 420b. The technician may rotate the screwdriver to the next potential position, causing switch 423 to rotate once again in the direction shown by the arrows so that first pole 424a contacts a third resistor 422a₃ of first resistor bank 420a and second pole 424b contacts a fourth resistor 422b₄ of second resistor bank 420b. This may continue as long as the technician continues rotating the screw driver until a last position is reached, at which switch 423 is rotated so that first pole 424a contacts a sixth resistor 422a₆ of first resistor bank 420a and second pole 424b contacts a first resistor 422bi of second resistor bank 420b.

[0051] Of course, the arrangements depicted in Figs.3-4 are just two examples of how variable resistance assemblies may be implemented. Other arrangements are possible. For example, each resistor bank 420 includes six resistors 422 (each applying a different resistance) corresponding to six discrete CCT settings. However, there may be more or less resistors 422 to correspond to more or less discrete CCT settings.

[0052] As another example, in some embodiments, a single pole switch may be provided, and actuation of user interface element 108 may correspondingly the single pole switch. In yet other embodiments, a potentiometer may be employed as a variable resistance assembly in addition to or instead of banks of discrete resistors. A potentiometer may be adjustable to provide variable amounts of resistance along a continuous spectrum, rather than the discrete resistances applied by variable resistance assembly 318 in Fig.3 and variable resistance assembly 418 in Fig.4.

[0053] Referring now to Fig.5, components of another example luminaire 500 configured with selected aspects of the present disclosure is presented schematically. Many components of Fig.5 are similar to those described in Fig.3, and thus are numbered and operate similarly. One difference between luminaire 500 of Fig.5 and luminaire 300 is that luminaire 500 includes a multi-output LED driver 510 that is operably coupled to two strings of LEDs, 506a and 506b, rather than the single output LED drivers 310a and 310b. In this example, a single rail step switch 523 may be operated in a manner similar to each rail of the dual rail step switch 323 of Fig.3 to selectively electrically couple a pole 524 with one of a series of leads. Depending on the resistance applied by variable resistance assembly 518 to dimming interface 512, LED driver 510 may selectively drive first string 506a in a first manner (e.g., with a particular fixed amount of current or a PWM scheme). Likewise, depending on the resistance applied by variable resistance assembly 518 to dimming interface 512, LED driver 510 may selectively drive second string 506b in a second manner (e.g., with a particular fixed amount of current or a PWM scheme) that may be the same as or different than the manner in which first string 506a is driven.

[0054] For example, in one embodiment, luminaire 500 may be operated as shown in Table 2, below:

Table 2

[0055] As shown above in Table 2, when 10 Ohms of resistance is applied by variable resistance assembly 518 to dimming interface 512, LED driver 510 applies 550 amps of current to first string 506a through a first port or channel, and applies 50 amps of current to second string 506b through a second port or channel. When 20 Ohms of resistance is applied by variable resistance assembly 518 to dimming interface 512, LED driver 510 applies 450 amps of current to first string 506a and 150 amps of current to second string 506b through a second port or channel. When 30 Ohms of resistance is applied by variable resistance assembly 518 to dimming interface 512, LED driver 510 applies 350 amps of current to first string 506a and 250 amps of current to second string 506b through a second port or channel. This continues as the resistance is toggled between the various levels shown in the left-most column. Accordingly, and in a manner similar to that depicted in Fig. 2 and shown in Table 1, each string may be powered with current so that their combined emitted light has a desired CCT, while maintaining a relatively consistent intensity. [0056] Fig.6 depicts an example method 600 of assembling a luminaire configured with selected aspects of the present disclosure, in accordance with various embodiments. While operations of Fig.6 are depicted in a particular order, this is not meant to be limiting. In various embodiments, various operations may be reordered, added, and/or omitted.

[0057] At block 602, a first string of LEDs may be operably coupled with a first output of one or more LED drivers (e.g., 210, 310, 510). As noted above, the first string of LEDs may be designed to output light having a particular CCT. For example, the individual LEDs of the first string may be associated with a particular LED bin, and may have predetermined flux and/or forward voltage characteristics.

[0058] At block 604, a second string of LEDs may be operably coupled with a second output of one or more LED drivers. Like the first string, the second string may be designed to output light having a particular CCT, and may include a selected number of individual LEDs that are associated with a particular LED bin, and/or that may have predetermined flux and/or forward voltage characteristics. Depending on the series of CCTs desired from the first and second strings in combination, the first and second strings may have different numbers of LEDs. Also, depending on the nature of the LED drivers employed, the second string may be operably coupled with the same LED driver as the first string (except at a different output), or may be operably coupled with a different LED driver.

[0059] At block 606, a variable resistance assembly (e.g., 218, 318, 418, 518) may be operably coupled with one or more dimming interfaces (e.g., via leads 314, 414, 514) of the one or more LED drivers. Then, once the LED drivers are powered (e.g., with A/C voltage), the variable resistance assembly may apply different amounts of resistance to the LED drivers, depending on the configuration of the variable resistance assembly (e.g., which resistors of a resistor bank are in contact with a switch).

[0060] At block 608, the one or more LED drivers may be programmed or otherwise configured to map predetermined resistances applied by the variable resistance assembly in its various configurations to desired current outputs to be provided to the first and second strings of LEDs. For example, suppose six different combined CCTs are desired from the luminaire. The variable resistance assembly may be transitionable between six different configurations in which six different sets of resistors are electrically coupled with the one or more dimming interfaces of the one or more LED drivers. Consequently, in each of the six configurations, the variable resistance assembly may apply a different resistance, such that the variable resistance assembly can be stepped through a series of six discrete resistances. The one or more LED drivers may be programmed to map each of the six discrete resistances to a first set of six current outputs (e.g., different amounts of current, or modulated using PWM) to be applied to the first string of LEDs, and to a second set of six current outputs to be applied to the second strings of LEDs.

[0061] While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. [0062] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

[0063] The indefinite articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one."

[0064] The phrase "and/or," as used herein in the specification and in the claims, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and/or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and/or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0065] As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" or "and/or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law. [0066] As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0067] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0068] In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03. It should be understood that certain expressions and reference signs used in the claims pursuant to Rule 6.2(b) of the Patent Cooperation Treaty ("PCT") do not limit the scope.

Claims

What is claimed is:

1. A luminaire (100, 200, 300, 500), comprising:

a housing (102);

a light-emitting diode ("LED") driver (210, 310, 510) with a dimming interface (312, 512) contained within the housing;

a string of LEDs (106, 206, 306, 506) operably coupled with an output of the LED driver; a user interface element (108) accessible from an exterior of the housing; and a variable resistance assembly (218, 318, 418, 518) contained in the housing and operably coupled with the dimming interface, the variable resistance assembly including a plurality of potential configurations in which the variable resistance assembly applies a predetermined resistance to the dimming interface;

wherein the variable resistance assembly is toggled between its potential configurations in response to physical actuation of the mechanical user interface element; and

wherein in response to each resistance applied by the variable resistance assembly in each respective potential configuration of the variable resistance assembly, the LED driver provides current in a different manner to the string of LEDs.

2. The luminaire of claim 1, wherein the variable resistance assembly comprises a bank of resistors (420).

3. The luminaire of claim 1, wherein the variable resistance assembly comprises a potentiometer.

4. The luminaire of claim 1, wherein each of the predetermined resistances provided by the variable resistance assembly is selected to cause the string of LEDs to emit light having a different correlated color temperature ("CCT").

5. The luminaire of claim 1, wherein the variable resistance assembly further comprises a switch (323, 423, 523) mechanically coupled with the user interface element.

6. The luminaire of claim 5, wherein physical actuation of the user interface element causes the switch to transition from electrically coupling a first set of one or more resistors of the variable resistance assembly with the dimming interface to electrically coupling a second set of one or more resistors of the variable resistance assembly with the dimming interface, wherein the first and second sets are different.

7. The luminaire of claim 6, wherein the switch is a dual pole switch.

8. The luminaire of claim 6, wherein the switch is a dual rail step switch.

9. The luminaire of claim 1, wherein the LED driver provides a pulse width modulated current to the string of LEDs in response to resistance applied by the variable resistance assembly in at least one potential configuration of the variable resistance assembly.

10. The luminaire of claim 1, wherein the string of LEDs comprises a first string of LEDs (106a, 206a, 306a, 506a) operably coupled with a first output of the LED driver, and the luminaire further comprises a second string of LEDs (106b, 206b, 306b, 506b).

11. The luminaire of claim 10, wherein the second string of LEDs is operably coupled with a second output of the LED driver, wherein in response to each resistance applied by the variable resistance assembly in each potential configuration of the variable resistance assembly, the LED driver provides current in a different manner to the second string of LEDs.

12. The luminaire of claim 10, wherein the second string of LEDs is operably coupled with an output of a second LED driver, a dimming interface of the second LED driver is operably coupled with the variable resistance assembly, and wherein in response to each resistance applied by the variable resistance assembly in each potential configuration of the variable resistance assembly, the second LED driver provides current in a different manner to the second string of LEDs.

13. A method, comprising:

operably coupling (602) a first string of light-emitting diodes ("LEDs") to a first LED driver output of one or more LED drivers, wherein the first string of light-emitting diodes emits light having a first correlated color temperature ("CCT");

operably coupling (604) a second string of light-emitting diodes to a second LED driver output of the one or more LED drivers, wherein the second string of LEDs emits light having a second CCT;

operably coupling (606) a variable resistance assembly to one or more dimming interfaces of the one or more LED drivers to which the first and second strings of LEDs are operably coupled, wherein the variable resistance assembly is configured to be transitioned between a plurality of potential configurations in which the variable resistance assembly applies a predetermined resistance to the one or more dimming interfaces; and

programming (608) the one or more LED drivers to map each predetermined resistance applied by the variable resistance assembly to a first desired current output for the first string of LEDs and a second desired current output for the second string of LEDs.

14. A system, comprising:

one or more light-emitting diode ("LED") drivers (210, 310, 510) having one or more dimming interfaces (312, 512);

at least two strings of LEDs (106a-b, 206a-b, 306a-b, 506a-b) operably coupled with at least two outputs of the one or more LED drivers;

a user interface element (108); and

a variable resistance assembly (218, 318, 418, 518) operably coupled with the one or more dimming interfaces, the variable resistance assembly including a plurality of potential configurations in which the variable resistance assembly applies one or more respective predetermined resistances to the one or more dimming interfaces;

wherein in response to each resistance applied by the variable resistance assembly in each respective potential configuration of the variable resistance assembly, the one or more LED drivers provide current in a different manner to the at least two strings of LEDs.

15. The system of claim 14, wherein the variable resistance assembly further comprises a switch (323, 423, 523) mechanically coupled with the user interface element, and wherein physical actuation of the user interface element causes the switch to transition from electrically coupling a first set of one or more resistors of the variable resistance assembly with the one or more dimming interfaces to electrically coupling a second set of one or more resistors of the variable resistance assembly with the one or more dimming interfaces, wherein the first and second sets are different.