WO2019232102A2

WO2019232102A2 - System and method for controlling a tunable lighting system

Info

Publication number: WO2019232102A2
Application number: PCT/US2019/034472
Authority: WO
Inventors: Stefan Lorenz; Biju Antony; Ashwani Guleria; Tiberiu ANTOHI; Arthur Gilenberg
Original assignee: Osram Sylvania Inc.; Osram Opto Semiconductors Gmbh
Priority date: 2018-05-29
Filing date: 2019-05-29
Publication date: 2019-12-05
Also published as: WO2019232102A3; DE112019002768T5

Abstract

A tunable lighting system for controlling the intensity and/or correlated color temperature (CCT) of light output from a tunable light source. In some embodiments, the system includes one or more switch modules for sending user commands for a desired intensity and/or CCT. A driver of the tunable light source drives one or more channels of a tunable lighting module using an adjustable constant current, a DC-DC converter with an adjustable output voltage and short circuit protection. In some embodiments, calculation of drive current for the light source is performed in real-time using parameters of the tunable lighting module. In some embodiments, a network collision avoidance process avoids network collisions by assigning any one of a plurality of switch modules on a network as a master.

Description

SYSTEM AND METHOD FOR CONTROLLING

A TUNABLE LIGHTING SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of the filing date of United States

Provisional Patent Application Serial No. 62/677,657, filed May 29, 2018 and entitled“Optimized Color Tuning Control”, United States Provisional Patent Application Serial No. 62/677,659, filed May 29, 2018 and entitled“Multi Channel Driver For Lighting System” and United States Provisional Patent Application Serial No. 62/677,662, filed May 29, 2018 and entitled“Systems and Methods for Network Collision Prevention”, the teachings of which applications are hereby incorporated herein by reference in their entirety.

FIELD

[0002] The present disclosure relates generally to lighting systems, and, more particularly, to systems and methods for controlling a tunable lighting system.

BACKGROUND

[0003] In the lighting industry, the use of solid-state light sources has provided numerous benefits over the traditional lighting sources in a variety of applications.

For example, solid state light sources generally provide greater energy efficiency and increased lifespan compared to traditional light sources. In addition, solid state light sources also provide a greater range of controllability.

[0004] For example, solid state lighting systems can be controlled so as to produce a range of different chromatic properties of light, adjustable to users’ requirements for a particular application and/or setting. The chromatic properties may include, for example, the appearance of the light source based on intensity and color temperature. The intensity, or illumination level, is a measure of the amount of useable light which is incident on a surface of an object. Color temperature, also referred to herein as correlated color temperature (CCT), is a description of color appearance of a light source in terms of its warmth or coolness. Light sources with a low color temperature generally have a yellow-white color and are described as “warm,” while lamps with a high color temperature have a blue- white color and are described as“cool.”

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Features and advantages of the claimed subject matter will be apparent from the following detailed description of embodiments consistent therewith, which description should be considered with reference to the accompanying drawings, wherein:

[0006] FIG. 1 is a block diagram illustrating an embodiment of a tunable lighting system consistent with the present disclosure;

[0007] FIG. 2 is a block diagram illustrating an embodiment of a switch module useful in a tunable lighting system consistent with the present disclosure;

[0008] FIG. 3 diagrammatically illustrates an embodiment of a switch module including a user interface useful in a tunable lighting system consistent with the present disclosure;

[0009] FIG. 4 is a block diagram of an embodiment of a driver useful in a tunable lighting system consistent with the present disclosure;

[0010] FIG. 5 is a block diagram illustrating an embodiment of a power module useful in a driver of a tunable lighting system consistent with the present disclosure.

[0011] FIG. 6 is a block diagram illustrating an embodiment of a constant current drive circuit useful in a power module of a tunable lighting system consistent with the present disclosure;

[0012] FIG. 7 is a circuit diagram illustrating an embodiment of a DC-DC converter with adjustable output voltage useful in a constant current drive circuit consistent with the present disclosure;

[0013] FIG. 8 is a circuit diagram illustrating an embodiment of a linear regulator and short circuit protection circuit useful in a constant current drive circuit consistent with the present disclosure;

[0014] FIG. 9 is a block flow diagram illustrating an embodiment of a color tuning method consistent with the present disclosure; [0015] FIG. 10 is a plot of color coordinates, C(x) vs. C(y), illustrating operations of an example embodiment of a color tuning operation consistent with the present disclosure;

[0016] FIG. 11 illustrates an example embodiment of a networked tunable lighting system including a plurality of switch modules and tunable light sources consistent with the present disclosure;

[0017] FIG. 12 is a block flow diagram illustrating an embodiment of a network collision avoidance routing consistent with the present disclosure; and

[0018] FIG. 13 is a flow chart illustrating another embodiment of a network collision avoidance routing consistent with the present disclosure.

[0019] For a thorough understanding of the present disclosure, reference should be made to the following detailed description, including the appended claims, in connection with the above-described drawings. Although the present disclosure is described in connection with exemplary embodiments, the disclosure is not intended to be limited to the specific forms set forth herein. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient. Also, it should be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

[0020] By way of a brief overview, the present disclosure is generally directed to a system and method for controlling a tunable light source to provide light output from the light source having a desired intensity and/or CCT. The system includes one or more switch modules for sending commands representative of the desired intensity and/or CCT to one or more tunable light sources. The tunable light sources include a driver configured to receive the commands and tune the light output of the light sources to the desired intensity and/or CCT represented by the commands.

[0021] In some embodiments, the driver may include a power module providing high output current accuracy, efficiency and a rapid response short circuit protection using a linear regulator in conjunction with a variable DC-DC controller and a short circuit protection scheme. The driver may operate in linear mode and minimize the effects of flicker caused by current ripple. The driver provides advances over the typical switched mode operation driver, which provides high efficiency power conversion, but with a side effect of lower current accuracy at low output current levels, thereby sacrificing a wide range of operation. The driver also provides advances over converters that use a hybrid power conversion scheme that transitions from switch mode to linear mode at low output currents.

[0022] In some embodiments, the tunable lighting system may include a color tuning process that determines the drive current for each channel for the tunable lighting module in response to a user demand for a desired intensity and CCT provide through a switch module. The process may be executed using a few basic parameters associated with the tunable lighting module(s) and the requirements of the application in which the system is used. The parameters may be stored in memory of the driver and the driver may access the parameters when executing the process to calculate the lumen contributions and drive currents for each channel of the tunable lighting modules in real time. This provides significant advantages compared to known systems that require calculation of a lumen contribution for each channel or light source and each CCT and storing the lumen contributions for each CCT in a look-up- table (LUT).

[0023] In some embodiments, the tunable lighting system may include a network collision avoidance algorithm using inexpensive and simple switch modules that are each able to serve as a master device. This avoids the limitations of known single master systems and the expense and complexity of known multi-master network systems.

[0024] A tunable lighting system consistent with the present disclosure may be used in a variety of settings where a user selectable light intensity and/or CCT is desired, such as in an industrial setting, a school setting, a healthcare facility, a home or apartment building, a restaurant, etc. Also, tuning the chromatic properties of light in a tunable lighting system consistent with the present disclosure can have a variety of effects. For example, if light of a first color temperature is associated with increased productivity during a first period of the work day, and light of a second (different) color temperature is associated with increased productivity during a second (different) period of the work day, and light of a third (different) color temperature is associated with increased productivity during a third (different) period of the work day, a solid state lighting system may be tuned to provide light emitted at those three different color temperatures during their respective periods of the work day. Of course, these changes in color temperature may be realized at the system level, and may also be realized at sublevels, such that, for example, the color temperature of light emitted from the system in a first office is different than the color temperature of light emitted from the system in a second office.

[0025] Reference will now be made in detail to exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings.

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Although the description may separately describe the configuration of some example embodiments of a tunable lighting system, it is to be understood that tunable lighting system consistent with the present disclosure may include any combination of embodiments described herein.

[0026] FIG. 1 is a block diagram illustrating one example embodiment of a tunable lighting system 100 for controlling lighting consistent with the present disclosure. The illustrated tunable lighting system 100 includes a switch module 102 coupled to a tunable light source 104 through a wired or wireless connection. The tunable light source 104 includes a tunable lighting module 106 and a driver 108. In general, the switch module 102 includes a user interface 110 and sends commands to the driver 108 in response to user input received through the user interface 110. In response to the commands from the switch module 102, the driver 108 provides drive current to tune the tunable lighting module 106 to provide a light output 112 having chromatic properties defined at least impart by one or more of the commands. In some embodiments, input voltage Vi_n to the system 100, e.g. 120VAC or 12VDC, may be hard wired to the system components individually or to the switch and the switch may provide power to the other components. In other embodiments, the switch and/or the tunable light source 104 may be powered by a battery (not shown).

[0027] Those of ordinary skill in the art will recognize the system 100 is depicted in highly simplified for in FIG. 1 for ease of explanation. A tunable lighting system 100 according to embodiments disclosed herein may include any number and/or types of components, including additional components not shown in FIG. 1 (e.g., sensors, controllers, non-tunable light sources, and the like). In some embodiments, the tunable lighting module 106 and the driver 108 may be configured in a fixture and/or directly installed within or attached to a wall, a ceiling, lamp, etc. The switch module 102 may be coupled to the driver 108 by a hard-wired or wireless (e.g. radio-based or optical) interface and may be configured as a fixed device installed within or mounted to a wall, ceiling or other surface, or as mobile device, such as a personal computer, smart phone or tablet. In some embodiments, one or more components of the switch module 102 may be housed in a housing with one or more components of the tunable light source 104.

[0028] In a tunable lighting system 100 consistent with the present disclosure tunable control of the light output 112 may be provided through use of one or more solid-state light source(s). A given solid-state light source may include one or more solid-state emitters, which may be any of a wide range of semiconductor light source devices, such as, for example: (1) a light-emitting diode (LED); (2) an organic light- emitting diode (OLED); (3) a polymer light-emitting diode (PLED); and/or (4) a combination of any one or more thereof. In some embodiments, a given solid-state emitter may be configured for emissions of a single correlated color temperature (CCT) (e.g., a white light-emitting semiconductor light source). In some other embodiments, however, a given solid-state emitter may be configured for color- tunable emissions. For instance, in some cases, a given solid-state emitter may be a multi-color (e.g., bi-color, tri-color, etc.) semiconductor light source configured for a combination of emissions, such as: (1) red-green-blue (RGB); (2) red-green-blue- yellow (RGBY); (3) red-green-blue-white (RGBW); (4) dual-white; and/or (5) a combination of any one or more thereof. As used herein, the term“color” is used interchangeably with the term“spectrum.” However, the term,“color” generally is used to refer to a property of radiation that is perceivable by an observer (though this usage is not intended to limit the scope of this term). Accordingly, the term“different colors” implies two different spectra with different wavelength components and/or bandwidths. In addition,“color” may be used to refer to white and non-white light.

[0029] Groups or strings of solid-state emitters may be combined into distinct channels that may be independently controlled by separate outputs of the driver 108 to achieve a desired intensity and/or CCT of the light output 112 by color- mixing or blending of the light emitted from the separate channels. In some embodiments, for example, the tunable lighting module 106 may be a known multi-color white light source including a known color-mixing multiple light-emitting diode (LED) arrangement. As generally understood, the LED arrangement may include a plurality of different color LED chips for emitting light of different respective colors, which are mixed to produce a color-mixed light output (e.g. white light) from the LED arrangement. The mixture of light emitted by each of the different color LED chips can cover a large part of the visible spectrum. An example of a known tunable lighting module including two channels of LED chips for producing a tunable white light output consistent with the present disclosure is the PrevaLED® tunable white light engine, which is commercially available from Osram Sylvania of Wilmington, Massachusetts.

[0030] For the purpose of this disclosure, the term“color temperature” or “correlated color temperature (CCT)” refers to a particular color content or shade (reddish, bluish, etc.) of white light. The color temperature of a radiation sample is conventionally characterized according to the temperature in degrees Kelvin (K) of a black body radiator that radiates essentially the same spectrum as the radiation under examination· The term“white” generally refers to white light with a CCT between about 2600 and 8000 K,“cool white” refers to light with a CCT closer to 8000 K, which is more bluish in color, and“warm white” refers to white light with a CCT of between about 2600 K and 4000 K, which is more reddish in color.

[0031] The switch module 102 may be provided in a variety of configurations. FIG. 2, for example, is a block diagram of one example of a switch module l02a useful in a tunable lighting system 100 consistent with the present disclosure. The illustrated example switch module l02a includes a switch controller 202, a power module 204, a communication interface 206, a memory 208 and the user interface 110. In general, the switch controller 202 receives user input from the user interface 110 and is configured to cause transmission of commands to one or more drivers 108 through the communication interface 110. Power for operating the switch controller 202 is provided by the power module 204, which may receive the input voltage V_m, e.g. 120VAC, and provide a regulated DC output voltage for operating the switch controller 202, communication interface 206 and the user interface 110. The power module 204 may be configured as a known AC-DC or DC-DC converter, e.g.

including a switching converter for providing the regulated DC output.

[0032] The communication interface 206 may take a variety of known configurations. In some embodiments, the communication interface 206 may include a known transmitter to allow the switch module l02a to communicate with the driver 108 using a digital communications protocol, such as a digital multiplexer (DMX) interface, a Wi-Fi™ protocol, a digital addressable lighting interface (DALI) protocol, a ZigBee ® protocol, a Bluetooth ® protocol or any other suitable communications protocol, wired and/or wireless, as will be apparent in light of this disclosure. For simplicity of explanation, the switch module 102 in FIG. 1 is shown to only be connected with one tunable light source 104, however any number of switch modules 102 and tunable light sources 104 may be connected in a networked tunable lighting system 100 consistent with the present disclosure.

[0033] The user interface 110 may be any interface upon which the user may be able to selectively control the chromatic properties of the light output 112 from the tunable light source 104. In some embodiments, the user interface 110 may include user controls such as one or more switches, a graphical user interface, a display screen, or combinations thereof to allow a user to control the intensity and/or CCT of the light output 112 of the tunable light source 104.

[0034] One example of a switch module l02a including a user interface llOa is illustrated in FIG. 3. In the illustrated embodiment, the switch module l02a includes a housing 302 and a plurality of switches 304, 306, 308, 310, 312, 314 mounted in the housing 302. The user may operate a Scene 1 switch 302 to select a first desired intensity and CCT of the light output 112 or a Scene 2 switch 304 to select a second desired intensity and CCT (Scene 2) of the light output 112. For example, the Scene 1 switch 303 may select a cool white light of relatively high intensity and the Scene 2 switch 304 may select a warm white light and relatively low intensity. The intensity and CCT associated with Scene 1 and Scene 2 switches 303, 304 may be stored in memory 208. The switch controller 202 may access the memory 208 to retrieve the stored intensity and CCT in response to activation of the Scene 1 or Scene 2 switch to cause transmission of a command to the driver 108 to tune the light output 112 of tunable lighting module 106 to the stored intensity and CCT.

[0035] In response to operation of an Intensity toggle switch 312 the switch controller 202 may cause transmission of a command to the driver 108 to increase or decrease the intensity of the light output 112 of the tunable lighting module 106. In response to operation of a Color toggle switch 314 the switch controller 202 may cause transmission of a command to the driver 108 to modify the color of light output 112 of the tunable lighting module 106, e.g. to a cooler white light or a warmer light. A Custom switch 308 may allow a user to store a custom setting established by operation of the Intensity and/or Color toggle switch 312, 314. For example, once a user sets a desired intensity and color setting for the light output 112 of the tunable lighting module 106 using the Intensity and Color toggle switches 312, 314 the user may depress the Custom switch 308 to save the intensity and color setting in the memory 208. Later operation of the Custom switch 308 then causes the switch controller 202 to access the saved intensity and color setting in memory 208 and cause transmission of a command to the driver 108 to tune the light output 112 of tunable lighting module 106 to the saved intensity and color setting. An On/Off switch 310 may allow a user to switch the tunable light source 104 to an on or off state.

[0036] The driver 108 may be provided in a variety of configurations. FIG. 4, for example, is a block diagram of one example of a driver l08a useful in a tunable lighting system 100 consistent with the present disclosure. In the illustrated example embodiment, the driver l08a includes a driver controller 402, a power module 404, a communication interface 406, a memory 408 and a programming interface 410. Commands to tune the light output 112 to a desired intensity and/or CCT setting are received from the switch module l02a by the communication interface 406. In response to the commands, the driver controller 402 provides drive current control signals to the power module 404. In response to the drive current control signals the power module 404 provides drive current, dependently or independently, to the tunable lighting module channel(s) to drive the tunable module channels to tune the intensity and/or CCT of the light output 112 of the tunable lighting module 106 to the desired intensity and/or CCT setting represented in the commands received from the switch module 102. The drive current control signals may also be configured to control the power module 404 for efficiently driving the tunable lighting module channels at low currents and with short circuit protection.

[0037] The communication interface 406 may include a known receiver configured to receive communications from communication interface 206 of the switch module 102 to facilitate communication of the commands therebetween. In some embodiments, power module 404 may include a known power AC-DC and/or DC-DC configuration for receiving the input voltage Vi_n, e.g. 120VAC, and providing a regulated output current to the tunable lighting module 106. The programming interface 410 may be a known interface configuration for allowing a user to program the driver controller 402 and/or store data in the memory 408 to provide drive current control signals based on known characteristics of the tunable lighting module 106.

The known characteristics may be stored in the memory 408 as tunable light source data 412 that may be accessed by the driver controller 402 to provide the drive current control signals to achieve the desired intensity and/or CCT settings represented by the commands from the switch module 102.

[0038] In some embodiments, the power module 404 may be configured to independently or dependently control each channel of the tunable lighting module 106. Advantageously, the driver l08a may provide very high output current accuracy, efficiency, and quick response short circuit protection with the use of a linear regulator in conjunction with a variable DC-DC controller in the power module 404. The driver l08a may operate in linear mode and reduce the effects of flicker caused by current ripple.

[0039] FIG. 5, for example, illustrates one example of a power module 404 consistent with the present disclosure for use with an AC input voltage V_m. The illustrated example embodiment includes an optional electro-magnetic interference (EMI) filter 502 and an AC-DC converter 504 that provides a DC output V_reg. The DC output V_reg of the AC-DC converter 504 is coupled in parallel to a constant current drive circuit 506-1...506-N associated with each channel 508-1...508-N of the tunable lighting module 106. Those of ordinary skill in the art will recognize that in an embodiment wherein the input voltage Vi_n is a DC input, the EMI filter 502 and the AC-DC converter 504 may be omitted.

[0040] The EMI filter 502 may take a known configuration to reduce EMI noise. The AC-DC converter 504 may include a rectifier configured to rectify the input voltage to provide an unregulated DC output and a known switching converter to receive the unregulated DC output of the rectifier and provide a stable, regulated DC output V_reg to each of the constant current drive circuits 506-1...506-N. A variety of rectifier circuits are well-known in the art.

[0041] A variety of switching converter configurations are also well-known in the art. Certain types of switching converters include known configurations, such as buck converters, boost converters, buck-boost converters, etc., which are generally categorized as switching regulators. These devices include a switch, e.g. a transistor, which is selectively operated to allow energy to be stored in an energy storage device, e.g. an inductor, and then transferred to one or more filter capacitors. The filter capacitor(s) provide a relatively smooth DC output voltage to the load and provide essentially continuous energy to the load between energy storage cycles. Another known type of switching converter includes a known transformer-based switching regulator, such as a“fly back” converter. In a transformer-based switching regulator, the primary side of the transformer may be coupled to the rectified AC output of the rectifier. The regulated DC output voltage is provided at the secondary side of the transformer which is electrically isolated from the primary side of the transformer.

[0042] In some embodiments, the input voltage Vi_n may be between about 120V- 277 V, e.g. +/- 10%, and the rectifier may include a known bridge rectifier. The switching converter of the AC-DC converter 504 may a known switched-mode fly back converter with power factor correction and may convert the output of the rectifier to a nominal constant DC output voltage V_reg, e.g. 58V DC.

[0043] Each constant current drive circuit 506-1...506-N provides an associated constant drive current l_L-i...l_L-N to an associated one of the channels 508-1...508-N of the tunable lighting module 106 in response to associated drive current control signals from the driver controller 402. The constant current drive current circuits 506-

1...506-N thus each drive an associated channel 508-1...508-N of the tunable lighting module 106 to emit an associated light output 112- 1...112-N. In this way the driver controller 402 controls the light output 112-1...112-N of each channel 508-

1...508-N of the tunable lighting module 106.

[0044] The driver controller 402 may be configured to control the light output 112-1...112-N from each channel 508-1...508-N of the tunable lighting module 106 in a channel mode or a tunable mode. In the channel mode, the driver controller 402 controls each constant current drive circuit 506-1...506-N independently in response to commands from the switch module 102 to provide separately controlled light output 112 from each of the channels 508-1...508-N of the tunable lighting module 106. In some embodiments, commands from the switch module 102 for

independently driving the constant current drive circuits 506-1...506-N may be DALI commands according to IEC 62386-l02-Device Type 6. In the tunable mode, the driver l08a controls all or a subset of the constant current drive circuits 506-1...506- N dependently to provide a mixed or blended output from a plurality of the tunable lighting module channels 508-1...508-N whereby the mixed output forms the light output 112 of the tunable light source 104 having the desired CCT and/or intensity. In some embodiments, commands from the switch module 102 for independently driving the constant current drive circuits 506-1...506-N may be DALI commands according to IEC 62386-102, 209-Device Type 8.

[0045] The constant current drive circuit 506-1...506-N for each channel 508- 1...508-N of the tunable lighting module 106 may be provided in a variety of configurations. FIG. 6, for example, illustrates one example of a constant current circuit 506a consistent with the present disclosure. The illustrated example embodiment 506a includes a DC-DC converter 602, a linear regulator 604 including a current control circuit 606 and a pass element 608, a short circuit protection circuit 610 and voltage sensing circuit 612. In general, the DC-DC converter 602 may convert the output voltage of the AC-DC converter 504 to a constant output voltage that is adjustable by the driver controller 402, e.g. between 10VDC and 50VDC in some embodiments. The driver controller 402 provides drive current control signals Iref to the linear regulator 604 to provide a constant drive current I_I through an associated one of the tunable lighting module channels 508 that is adjustable in response to commands received by the driver l08a from the switch module 102.

[0046] In some embodiments, the driver controller 402 may provide an adjustment signal V_adj to the DC-DC converter 602 to adjust the output to the DC-DC converter 602 to control the value of the output voltage V_out of the DC-DC converter 602 depending on the voltage drop associated with the solid-state light sources (e.g. LEDs) in the tunable lighting module channel. In some embodiments, to minimize losses in the linear regulator 604 and thereby improve efficiency, the voltage across pass element 608 is maintained at a low value, e.g. 300mV in some embodiments, using a feedback signal to driver controller 402 sensed across the switch by the voltage sensing circuit 612. The driver controller 402 may be configured to adjust the output of the DC-DC converter 602 in response to the feedback signal to maintain the voltage across the pass element 608 at a desired level. In some embodiments, the driver controller 402 may provide an offset signal V_offset to the current control circuit 606 of the linear regulator 604 so that any output current demand to the current control circuit 606 of the linear regular below the offset signal will result in approximately zero output current of the linear regulator 604. In some embodiments, the short circuit protection circuit 610 may immediately disable the pass element 608 in the event of a short circuit across the tuning lighting module channel to protect the circuit from damage. In some embodiments, in response to the short circuit the driver controller 402 may reduce the output voltage of the DC-DC converter 602 and ramp the voltage up after the short circuit is removed. Any of these features, any combination of these features, or all of these features may be provided in a driver l08a consistent with the present disclosure.

[0047] The DC-DC converter 602 may be a known switching regulator. In some embodiments, for example, the DC-DC converter 602 may have a known buck converter configuration. Voltage feedback control of the DC-DC converter 602 may be used to establish a stable output voltage. The value of the output voltage V_out may be adjusted by the adjustment signal V_adj from the driver controller 402.

[0048] FIG. 7 for example illustrates one example of a DC-DC converter 602a in a buck converter configuration including a MOSFET switch Ql, a diode Dl, an inductor L, a diode D2, a capacitor Cl, a known switching controller 702 and a voltage divider configuration including resistor Rl and resistor R2 for providing voltage feedback to the switching controller 702. The output V_reg of the AC-DC converter 504 is coupled to the switch Ql and, as is known, the switching controller 702 provides a switching control signal to the gate of switch Ql to control current flow to the inductor L. To maintain a constant output voltage V_out, the switching controller 702 adjusts its switching control signal to the switch Ql in response to voltage feedback received at a voltage feedback input from the voltage divider of Rl and R2. The value at the voltage feedback input to the switch controller 702 thus sets the constant output V_out of the DC-DC converter 602a.

[0049] In some embodiments of a driver l08a consistent with the present disclosure the voltage adjust signal V_adj may be coupled to the voltage divider to modify the voltage feedback signal to the switching controller 702. In the embodiment 602a shown in FIG. 7, for example, the voltage adjust signal V_adj is coupled to the node A between resistor Rl and resistor R2 of the voltage divider through resistor R3, resistor R4 and C2. The constant output voltage V_out of the DC- DC converter 602a may thus be adjusted by the voltage adjust signal V_adj from the driver controller 402.

[0050] With reference again to FIG. 6, the linear regulator 604 may take a variety of known configurations. In some embodiments, the current control circuit 606 of the linear regulator 604 includes an error amplifier and a voltage reference circuit and the pass element 608 may be a transistor such as a metal oxide field effect transistor (MOSFET) or a bipolar junction transistor (BJT). In general, the pass element 608 is driven by the error amplifier, which senses the output voltage and compares it with the reference voltage to maintain constant current through the pass element 608.

[0051] In some embodiments of a system consistent with the present disclosure, the driver controller 402 may provide a current reference signal I_ref to the current controller to adjust the voltage at one input of the error amplifier and thereby adjust the constant current I_I established by the linear regulator 604. In some embodiments, the driver controller 402 may also, or alternatively, provide a voltage offset signal V _offset to another input of the error amplifier so that any output current demand to the current control circuit 606 of the linear regular 604 below the offset signal V_offset will result in zero output current of the linear regulator 604 to reduce the effect of noise in the system.

[0052] FIG. 8 for example illustrates one example of a linear regulator 604a configuration useful in some embodiments consistent with the present disclosure.

The illustrated example embodiment 604a includes resistor R5, resistor R6, capacitor C3, Op-Amp Ul, resistor R7, resistor R8, capacitor C4, resistor R9, MOSFET Q2, resistor R10, resistor Rl 1 and capacitor C5. A current control circuit 606a is established R5, R6, C3, Ul, R7, R8, C4 and R9, and Q2 acts as a pass element 608a.

[0053] The reference signal I_ref is coupled to the non-inverting input through R5 and the parallel combination of R6 and C3 to provide a reference voltage to Ul based on the reference signal I_ref. The reference signal I_ref may thus control the output current of the linear regulator 604a. The inverting input of Ul is coupled to the output of Ul by the parallel combination of R8 and C4 and to the offset signal V_0ffset from the driver controller 402 through R7. The output of Ul is coupled to the gate of Q2 through R9. The tunable lighting module channel 508 is coupled between the output voltage V_out of the DC-DC converter 602 and the drain of Q2. The source of Q2 is coupled to ground through R10, Rl 1 and C5. The parallel combination of C5, Rl 1 and R10 is coupled to the inverting input of Ul to provide current feedback representative of the current through Q2.

[0054] With this configuration the linear regulator 604a maintains a constant current I_I through the tunable lighting module channel 508 that is adjustable by the driver controller 402 through adjustment of the reference signal I_ref. The offset signal V _offset is provided so that any output current demand of the linear regulator 604a below the offset signal V_0ffset will result in approximately zero output current of the linear regulator 604a, thereby reducing the effects of noise in the system.

[0055] The voltage sensing circuit 612 may also take a variety of known configurations for providing a feedback signal to the driver controller 402 and maintaining a voltage V_sense across the pass element 608 at a low level, e.g. about 300mV. With reference again to FIG. 8, in some embodiments, for example, the voltage sensing circuit 612 may include an amplifier to amplify the drain voltage of Q2 and a differential amplifier coupled to the amplified drain voltage and the source voltage of Q2 to provide a feedback signal representative of the voltage across Q2.

[0056] The short circuit protection circuit 610 may be configured to immediately disable the pass element 608 of the linear regulator 604 in the event of short circuit in the tunable lighting module channel 508. A variety of configurations for the short circuit protection circuit 610 are possible. One example embodiment of a short circuit protection circuit 6l0a is illustrated in FIG. 8. In the illustrated example, the short circuit protection circuit 6l0a includes a BJT Q3, resistor R12, resistor R13, Zener diodes D3 and D4 and capacitor Cl. The collector of Q3 is coupled to the gate of Q2 and the emitter if Q3 is coupled to ground. The base of Q3 is coupled to the drain of Q2 through R12 and the series combination of D3 and R13 also to ground through the parallel combination of D4 and C6. In normal operation, i.e. in the absence of a short circuit in the tunable light source channel 508, Q3 is non conducting. In the event of short circuit across the tunable light source channel 508, the voltage across the Zener diode D3 is exceeded, which turns Q3 on (conducting) and immediately turns Q2 off (non-conducting), thereby protecting the driver l08a from damage.

[0057] In some embodiments, the driver controller 402 may also, or alternatively, infer the occurrence of a short circuit in a tunable light source channel 508 from the feedback signal of the voltage sensing circuit 612 and reduce the voltage output V_out of the DC-DC converter 602 using the adjustment signal V_adj. For example, when the voltage V_Sense sensed by the voltage sensing circuit 612 exceeds a predetermined value, e.g. 3V in some embodiments, the driver controller 402 may provide a voltage adjustment V_adj signal to the DC-DC converter 602 to reduce the voltage V_out to a very low value to protect the driver l08a. When the short circuit is removed, the driver controller 402 may modify the voltage adjustment signal V_adj to the DC-DC converter 602 to slowly ramp up the output voltage V_out of the DC-DC converter 602. This provides a soft-start feature on the output current I_I to the tunable lighting module channel 508 to minimize current spikes at the output of the DC-DC converter 602.

[0058] In some embodiments, the feedback signal from the voltage sensing circuit 612 may be used in combination with the reference signal I_ref to infer the state of the output for satisfying reporting requirements. For example, if I_ref is greater than or equal to 0 and V_sense indicates a voltage across the pass element 608 of 0V, then there is an open load. If I_ref is greater than 0 and V_sense indicates a voltage across the pass element 608 of approximately equal to the set voltage across the pass element 608, e.g. 0.3 V, then the circuit is in normal operation. If I_ref is greater than 0 and V_sense indicates a voltage across the pass element 608 of significantly more than the set voltage across the pass element 608, e.g. 3 V, then there is a short circuit condition. These conditions may be saved in the memory 408 of the driver l08a along with time and date information for later reference.

[0059] Color Tuning

[0060] Advantageously, in some embodiments, a driver l08a of a tunable lighting system 100 consistent with the present disclosure may execute a color tuning control process (CTCP) that determines the drive current IL-I . . TL-N for each channel 508- 1...508-N of the tunable lighting module 106 in response to a user demand for a desired intensity and CCT provide through the switch module 102. The CTCP may be executed using a few basic parameters associated with the tunable lighting module(s) 106 and the requirements of the application in which the system is used. The parameters may be stored in memory 408 of the driver l08a. The driver l08a may access the parameters when executing the CTCP to calculate the lumen contributions and drive currents IL-I . . TL-N _for each channel 508-1...508-N of the tunable lighting modules 106 in real-time.

[0061] Any variation occurring in system components, e.g. due to production tolerances, or to the production environment can easily be updated in the driver memory 408, e.g. through the programming interface 410. This provides significant advantages compared to known systems that require calculation of a lumen contribution for each channel or light source and each CCT and storing the lumen contributions for each CCT in a look-up-table (LUT). In such known systems, it can be time consuming and impractical to re-generate the LUTs when light source characteristics change with new production parts.

[0062] For ease of explanation, example embodiments of a CTCP will be described herein in connection with a single tunable lighting module 106 having two channels, i.e. two primary light sources. The terms“channel” and“primary light source” may be used interchangeably herein. It is to be understood, however, that a CTCP consistent with the present disclosure may be implemented using any number of tunable lighting modules 106 and any number of channels 508-1...508-N. The two primary light sources discussed in connection with example embodiments herein are described as a“cool white” primary light source and“warm white” primary light source. In general, the cool white primary light source has a higher CCT than the warm white primary source. In some embodiments, the cool white light source may have a CCT between about 2600 K and 4000 K and the warm white light source may have a CCT between about 6600 K and 8000 K.

[0063] The channels 508-1...508-N used in a system or method consistent with the present disclosure need not generate white light and need not produce a color on a black body curve. Indeed, since example embodiments described herein use two channels with different CCTs, the blended light output of the two channels is on a straight line (sometimes referred to herein as the CIE line) connecting the color coordinates of the two channels. Due to this linear control, the CTCP will not follow the black body curve.

[0064] The CTCP may be implemented in a variety of ways using parameters associated with the tunable light sources 104. The parameters may vary depending on the type and configuration of the tunable light sources 104 and the application.

Advantageously, however, a CTCP consistent with the present disclosure does not require pre-calculation of a lumen contribution for each channel 508-1...508-N and storing the contributions in a LUT.

[0065] In one example of CTCP consistent with the present disclosure, the following parameters may be used to calculate the lumen contributions and drive currents I_L-I . . T_L-N for each channel 508-1...508-N, i.e. each primary light source, of the tunable lighting modules 106 in real time: 1. The number of tunable lighting modules 106 in the tunable light source;

2. The number of channels in each tunable white module;

3. The number of solid-state light sources in each channel;

4. The maximum flux associated with each channel of the tunable lighting module(s) 106;

5. The color coordinates of each channel of the tunable lighting module 106;

6. Normalized lumen to drive current relationship for each of channel of the tunable lighting module 106; and

7. The maximum lumens need for the application.

These parameters may be stored in memory 408 of the driver l08a as the tunable light source data 412, e.g. using the programming interface 410. In operation, the driver l08a may receive a desired intensity and CCT from user through the switch module 102 and execute the CTCP using the parameters accessed from memory 408 to calculate drive current(s) IL-I . . TL-N required to provide an output of the tunable lighting module 106 representative of the desired intensity and CCT. The driver l08a may then drive the tunable lighting module 106 at the calculated drive current(s) I_I- l . . TL-N-

[0066] FIG. 9 is a flow chart of one example of a CTCP 900 consistent with the present disclosure. In general, the CTCP includes receiving 902 the desired intensity and CCT from the user. The desired intensity and/or CCT may be provided by the user using the user interface 110 of the switch module 102 and the switch module 102 may send commands to the driver l08a representative of the desired intensity and CCT, e.g. as described above. The CTCP may calculate 904 the lumens required for each channel 508-1...508-N to achieve the desired intensity and CCT in the blended light output 112 of the channels 508-1...508-N. The CCT may then calculate 906 the drive current IL-I .. TL-N for each channel 508-1...508-N based on the calculated lumens required for each channel 508-1...508-N. The calculations in operations 904 and 906 may be performed by accessing the parameters of the tunable light source 104 and the application stored in memory 408 of the driver l08a.

[0067] The lumens required for each channel 508-1...508-N to achieve the desired CCT in operation 904 of FIG. 9 may be calculated in a variety of ways. One example method of calculating the lumens required for each channel 508-1...508-N may be understood with reference to FIG. 10, which includes plots of color coordinates, C(x) vs. C(y). FIG. 10 includes a plot 1002 of a black body curve, a plot 1004 of an imaginary line with a pre-determined fixed offset from the black body curve 1002 and a plot 1006 of the color coordinates of the blended light output (CIE line) 112 associated with a tunable lighting module 106 having three primary light sources, i.e. a cool white, a warm white and a light source having a CCT of about 4000k in the illustrated example. The points 1008, 1010 and 1012 of the CIE line 1006 are determined from the CCT associated with each primary light source. In the illustrated example embodiment, the right end point 1008 represents the CCT of the warm white primary light source, the middle point 1010 represents the CCT of the 4000k primary light source and the left end point 1012 represents the CCT of the cool white primary light source. The CIE line 1002 is drawn by connecting the points 1008, 1010 and 102. To perform the calculation, data representing the black body curve 1002, the pre-determined offset from the black body curve 1004 and the CIE line 1006 are stored in memory 408 of the driver l08a.

[0068] Since the CIE line 1006 (representing the possible CCTs associated with the blended output of the primary light sources) is linear and does not precisely follow the black body curve 1002, it may not be possible to precisely replicate the desired CCT desired by the user if the desired CCT is on the black body curve 1002 but not on the CIE line 1006. Reference herein to“achieving” the desired CCT setting or light“corresponding” to the desired CCT setting or tuning a channel“to the desired setting” should thus be understood that the blended output light 112 of the primary light sources may not precisely match the desired CCT setting, but instead is an approximation of the desired CCT setting given the limitations of the CCTs achievable by blending the light output of the primary light sources and tolerances of the system. In general, using more primary light sources allows a closer match to the desired CCT.

[0069] In some embodiments, to achieve a close match to the desired CCT a point on the black body curve 1002 corresponding to the desired CCT received from the user is identified. In the example of FIG. 10, the point may be point Pl, for example. A Judd line 1014 is determined from the point Pl on the black body curve 1002 corresponding to the desired CCT to a point P2 on the imaginary line 1004 having the same CCT as the point Pl on the black body curve 1002. The Judd line 1014 defines coordinate pairs of the same CCT. The lumens required for each channel 508- 1...508-N are then calculated based on minimum lumen values of the channels, along with ratios of the C(x) and C(y) coordinates of each channel 508-1...508-N and the ratio represented by the intersection between the CIE line 1006 and the Judd linel0l4. In some embodiments, the duty cycle of the drive currents IL-I . . .IL-N may also be considered.

[0070] Calculating the drive current IL-I . . .IL-N for each channel 508-1...508-N based on the calculated lumens required for each channel 508-1...508-N in operation 906 of FIG. 9 may be accomplished in a variety of ways. In one example, the CTCP may determine the lumen gain based on the desired max lumens for the application and the calculated lumens required for each channel 508-1...508-N, along with the number of channels 508-1...508-N and number of light sources in each channel 508- 1...508-N and a constant representative of the lumen depreciation of the light sources due to heat. The lumen gain is then multiplied by the intensity level desired by the user and the lumens per light source, and this calculation is done for each of the channels 508-1...508-N. The drive current IL-I . . . IL-N for each channel 508-1...508-N is then found by using this value for each channel 508-1...508-N along with the lumens and the lumen depreciation constants for each channel 508-1...508-N. The overall current for the tunable lighting module 106 is determined by multiplying the current for each of the light sources by the number of strings.

[0071] Network Collision Avoidance

[0072] Turning now to FIG. 11, there is illustrated an example of a tunable lighting system 100 consistent with the present disclosure including a plurality of switch modules 102-1...102-N and a plurality of tunable light sources 104-1...104-N coupled in a network 1100. The switch modules 102-1...102-N and tunable light sources 104-1...104-N may communicate with each over the network 1100 using any known digital communication protocol, such as DALI. Input voltage Vi_n to the switch modules 102-1...102-N and tunable light sources 104-1...104-N may be hard wired or coupled to the devices using the network connections. Each of the switch modules 102-1...102-N may be configured to send commands, e.g. as previously described herein, representative of a desired intensity and/or CCT. The commands from each switch module 102-1...102-N may be transmitted to, and received by, one or more of the tunable light sources 104-1...104-N and one or more of the other switch modules 102-1...102-N on the network 1100.

[0073] One challenge associated with including multiple switch modules 102-

1...102-N on the network 100, each able to send commands to multiple ones of the tunable light sources 104-1...104-N, is that a single tunable light source 104-1...104-N may receive multiple separate commands from different switch modules 102-1...102- N. This is referred to as a“network collision.”

[0074] Known systems have attempted to solve this network collision problem by having one device function as the master device. The master device monitors and controls traffic on the network. This may work reasonably well for smaller networks with few devices. However, a master device typically has limitations with respect to how many other devices it can serve. Thus, when network includes many devices connected thereto, the number of devices that can serve as the master device on the entire network are few. One attempt to solving this problem has been to use multi master devices. However, these devices are relatively expensive and require extensive set up, which requires additional resources when setting up the network. Also, multi-master devices can be costly to replace or repair.

[0075] In some embodiments, a tunable lighting system 100 consistent with the present disclosure is configured to prevent network collisions using inexpensive and simple switch modules 102-1...102-N that are each able to serve as a master device.

In general, each switch module 102-1...102-N may have a network collision avoidance routine stored in memory 208 thereof. The network collision avoidance routine includes computer readable instructions that when executed by the switch module 102-1...102-N avoids network collisions resulting from separate commands received at a single tunable light source 104 from separate switch modules 102-

1...102-N. The routine sets any switch module 102-1...102-N that has sent a command as active and sets all other switch modules 102-1...102-N as inactive until the command is executed. In this way, any switch module 102- 1...102-N that has sent a command is the network master and any of the switch modules 102-1...102-N may become the master. As used herein, when a switch module 102-1...102-N is set to“active” the switch module 102-1...102-N may send commands on the network 1100 and when a switch module 102-1...102-N is“inactive” the switch module 102-

1...102-N may not send commands on the network 1100. [0076] FIG. 12, for example is a flow chart of one example 1200 of a network collision avoidance routine consistent with the present disclosure. As shown, in operation 1202 the routine determines if a user interface 110 control, e.g. a switch or button, of the switch module 102-1...102-N has been activated. If a user interface 110 control of the switch module 102-1...102-N has been activated the routine causes the switch module 102-1...102-N to send a command on the network to set 1204 all other switch modules 102-1...102-N in the network to an inactive state. The switch module 102-1...102-N then sends 1206 a command to one or more of the tunable light sources 104-1...104-N associated with activation of user interface 110 control, e.g. the command may instruct the tunable light sources 104-1...104-N to increase intensity of its light output 112 and/or the CCT of its light output 112. The switch module 102- 1...102-N may then send a command on the network to set 1208 all the other switch modules 102-1...102-N to an active state.

[0077] The example network collision routine 1200 illustrated in FIG. 12 may be implemented in a variety of ways. FIG. 13, for example, is a flowchart of one example implementation of a network collision avoidance routine 1300 consistent with the present disclosure. In the illustrated example, one of the switch modules 102-1...102-N sends a command on the network 1100 to set 1302 all of the switch modules 102-1...102-N on the network 1100 to an active state. After this operation 1302 all the switch modules 102-1...102-N on the network 1100 are able to receive and processes one or more commands on the network 1100.

[0078] Upon receiving a command, the switch module 102 performing the routine 1300 processes 1304 the command and determines 1306 if the received command is a command to set the switch module 102 to an inactive state. If the received command is to set the switch module 102 to an inactive state, the switch module 102 is set 1308 inactive and sets a timer 1310 and returns to operation 1304. If the received command is not to set the switch module 102 to an inactive state, then the routine 1300 determines 1312 if the command is to set the switch module 102 as active. If the command is not to set the switch module 102 as active, then, if the timer has not expired 1314 the routine 1300 returns to operation 1304, otherwise the switch module is set 1316 active.

[0079] The routine 1300 then monitors the user interface 110 controls, e.g.

buttons or switches, to determine 1318 if a user has activated a user interface 110 control, e.g. depressed a switch. If a user interface 110 control is not activated the routine 1300 returns to operation 1304. If a user interface 110 control is activated, then the routine 1300 determines 1320 if a network collision has occurred. In some embodiments, the routine 1300 may determine if a network collision occurred by determining if the switch module 102 has received other commands to control the same tunable light source 104 that is associated with activation of the user interface 110 control.

[0080] If a network collision has occurred, then the routine 1300 returns to operation 1304 after a random delay 1322. In some embodiments, if a network collision has occurred then the routine 1300 may send a command on the network 1100 to set all other switch modules 102-1...102-N to inactive. If a network collision has not occurred, then the routine 1300 sends 1324 a command on the network 1100 to set all other switch modules 102-1...102-N on the network 1100 in an inactive state sends 1326 the command associated with the user interface 110 control. After a delay 1328 to allow execution of the command, the routine 1300 sends 1330 a command to force all other switch modules 102-1...102-N on the network 1100 back to an active state and returns to operation 1304.

[0081] The rectangular elements of FIG. 13 are herein denoted "processing blocks" and represent computer software instructions or groups of instructions. The diamond shaped elements are herein denoted "decision blocks" and represent computer software instructions, or groups of instructions, which affect the execution of the computer software instructions, or groups of instructions, represented by the processing blocks. Alternatively, the processing and decision blocks represent steps performed by functionally equivalent circuits such as a digital signal processor circuit or an application specific integrated circuit (ASIC). The flowchart does not depict the syntax of any particular programming language. Rather, the flowchart illustrates the functional information one of ordinary skill in the art requires to fabricate circuits or to generate computer software to perform the processing required in accordance with embodiments of the present invention. It should be noted that many routine program elements, such as initialization of loops and variables and the use of temporary variables, are not shown. It will be appreciated by those of ordinary skill in the art that unless otherwise indicated herein, the particular sequence of steps described is illustrative only and can be varied without departing from the spirit of the invention. Thus, unless otherwise stated, the steps described herein are unordered, meaning that, when possible, the steps can be performed in any convenient or desirable order.

[0082] According to one aspect, there is provided a system for controlling a tunable light source, the system including: a tunable lighting module including at least one channel including at least one solid-state light source; a switch module configured to provide at least one command representative of a desired setting for a light output of the at least one channel; and a driver coupled to the switch module and configured to receive the at least one command and provide a drive current to the at least one channel in response to at least one command to tune the at least one channel to the desired setting. The driver includes a driver controller and a power module. The power module includes a DC-DC converter for providing an output voltage to the at least one channel, the output voltage being adjustable in response to an adjustment signal provided to the DC-DC converter from the driver controller; and a linear regulator for establishing a constant drive current through the at least one channel, the drive current being adjustable in response to a reference signal provided to the linear regulator from the driver controller.

[0083] According to another aspect, there is provided a method of controlling a tunable light source including a tunable lighting module having at least one channel including at least one solid-state light source. The method includes coupling an output of a DC-DC regulator to at least one channel of the tunable lighting module; coupling the at least one channel to a linear regulator to provide a constant current through the at least one channel; receiving a command from a switch module to adjust a light output of the at least one channel to a desired setting; adjusting the constant current through the at least one channel in response to the command using a reference signal applied to a linear regulator; sensing a voltage across a pass element of the linear regulator; determining an adjustment voltage in response to the voltage across the pass element; and coupling the adjustment voltage to the DC-DC regulator to adjust the output in response to the voltage across the pass element.

[0084] According to another aspect, there is provided a system for controlling a tunable light source including: a tunable lighting module including a plurality of channels, each of the plurality of channels being configured to provide light output having a different associated correlated color temperature (CCT); a switch module configured to provide at least one command representative of a desired CCT of a blended light output of the plurality of channels; and a driver coupled to the switch module and configured to receive the at least one command, the driver configured to calculate the lumens required to drive each of the plurality of channels to achieve the desired CCT and to calculate an associated drive current for each of the plurality of channels based on the calculated lumens required to drive each of the plurality of channels to achieve the desired CCT, the driver configured to drive each of the plurality of channels with the associated drive current.

[0085] According to another aspect, there is provided a method for controlling light source including a tunable lighting module including a plurality of channels, each of the plurality of channels being configured to provide light output having a different associated correlated color temperature (CCT). The method includes receiving a command representative of a desired CCT of a blended output of the plurality of channels; calculating lumens required to drive each of the plurality of channels to provide a light output from the plurality of channels corresponding to the desired CCT; and calculating an associated drive current for each of the plurality of channels based on the calculated lumens required to drive each of the plurality of channels provide a blended light output from the plurality of channels corresponding to the desired CCT.

[0086] According to another aspect, there is provided a system for controlling a tunable light source including: a plurality of tunable lighting modules coupled to a network; a plurality of switch modules coupled to the network, each of the switch modules being configured to send commands to one or more of the plurality of tunable lighting modules and the other ones of the plurality of switch modules coupled to the network, each of the switch modules including a non-transitory computer-readable memory having instructions stored thereon, which when executed by a switch controller of one of the plurality of the switch modules cause the switch controller to perform a network collision avoidance routine including: determining if a user interface control of the switch module has been activated; setting all the other of the plurality of switch modules in an inactive state if the user interface control of the switch module has been activated; sending one of the commands associated with activation of the user interface control; and setting ah of the other plurality of switch modules in an active state after sending the one of the commands. [0087] According to another aspect, there is provided a method for avoiding network collisions in a network including a plurality of tunable light sources and a plurality of switch modules. The method includes determining if a user interface control of one of the switch modules has been activated; setting all the other of the plurality of switch modules in an inactive state if the user interface control of the one of the switch modules has been activated; sending a command to one of the tunable light sources associated with activation of the user interface control; and setting all of the other plurality of switch modules in an active state after sending the one of the commands.

[0088] The foregoing description of example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future-filed applications claiming priority to this application may claim the disclosed subject matter in a different manner and generally may include any set of one or more limitations as variously disclosed or otherwise demonstrated herein.

[0089] Embodiments of the methods described herein may be implemented using a controller, processor and/or other programmable device. To that end, the methods described herein may be implemented on a tangible, non-transitory computer readable medium having instructions stored thereon that when executed by one or more processors perform the methods. Thus, for example, switch controller 202 and/or the driver controller 402 may include a storage medium to store instructions (in, for example, firmware or software) to perform the operations described herein. The storage medium may include any type of tangible medium, for example, any type of disk including floppy disks, optical disks, compact disk read-only memories (CD- ROMs), compact disk rewritables (CD-RWs), and magneto-optical disks, semiconductor devices such as read-only memories (ROMs), random access memories (RAMs) such as dynamic and static RAMs, erasable programmable read only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), flash memories, magnetic or optical cards, or any type of media suitable for storing electronic instructions. [0090] It will be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the disclosure. Similarly, it will be appreciated that any block diagrams, flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. Software modules, or simply modules which are implied to be software, may be represented herein as any combination of flowchart elements or other elements indicating performance of process steps and/or textual description. Such modules may be executed by hardware that is expressly or implicitly shown.

[0091] Further, while the block flow diagrams and flowchart shown herein illustrate various operations, it is to be understood that not all of the operations depicted in the therein are necessary for other embodiments to function. Indeed, it is fully contemplated herein that in other embodiments, the operations and/or other operations described herein, may be combined in a manner not specifically shown in any of the drawings, but still fully consistent with the present disclosure. Thus, claims directed to features and/or operations that are not exactly shown in one drawing are deemed within the scope and content of the present disclosure.

[0092] The functions of the various elements shown in the figures, including any functional blocks labeled as "controller", may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. The functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term "controller" should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and/or custom, may also be included.

[0093] As used in any embodiment herein, a“circuit” or“circuitry” may comprise, for example, singly or in any combination, hardwired circuitry, programmable circuitry, state machine circuitry, and/or firmware that stores instructions executed by programmable circuitry.

[0094] The term“coupled” as used herein refers to any connection, coupling, link or the like by which signals carried by one system element are imparted to the “coupled” element. Such“coupled” devices, or signals and devices, are not necessarily directly connected to one another and may be separated by intermediate components or devices that may manipulate or modify such signals. Likewise, the terms“connected” or“coupled” as used herein in regard to mechanical or physical connections or couplings is a relative term and does not require a direct physical connection.

[0095] Elements, components, modules, and/or parts thereof that are described and/or otherwise portrayed through the figures to communicate with, be associated with, and/or be based on, something else, may be understood to so communicate, be associated with, and/or be based on in a direct and/or indirect manner, unless otherwise stipulated herein.

[0096] Unless otherwise stated, use of the word "substantially" or

“approximately” may be construed to include a precise relationship, condition, arrangement, orientation, and/or other characteristic, and deviations thereof as understood by one of ordinary skill in the art, to the extent that such deviations do not materially affect the disclosed methods and systems. Throughout the entirety of the present disclosure, use of the articles "a" and/or "an" and/or "the" to modify a noun may be understood to be used for convenience and to include one, or more than one, of the modified noun, unless otherwise specifically stated. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0097] Although the methods and systems have been described relative to a specific embodiment thereof, they are not so limited. Obviously many modifications and variations may become apparent in light of the above teachings. Many additional changes in the details, materials, and arrangement of parts, herein described and illustrated, may be made by those skilled in the art.

Claims

CLAIMS What is claimed is:

1. A system for controlling a tunable light source, the system comprising:

a tunable lighting module including at least one channel comprising at least one solid- state light source;

a switch module configured to provide at least one command representative of a desired setting for a light output of the at least one channel; and

a driver coupled to the switch module and configured to receive the at least one command and provide a drive current to the at least one channel in response to at least one command to tune the at least one channel to the desired setting, the driver comprising:

a driver controller; and

a power module, the power module comprising:

a DC-DC converter for providing an output voltage to the at least one channel, the output voltage being adjustable in response to an adjustment signal provided to the DC- DC converter from the driver controller; and

a linear regulator for establishing a constant drive current through the at least one

channel, the drive current being adjustable in response to a reference signal provided to the linear regulator from the driver controller.

2. The system of claim 1, wherein the linear regulator comprises a current control circuit and a pass element, and wherein the power module further comprises a voltage sense circuit configured to provide a feedback signal to the driver controller

representative of a voltage across the pass element, wherein the adjustment signal is provided in response to the feedback signal to maintain the voltage across the pass element at a desired voltage

3. The system of claim 1, wherein the linear regulator comprises a current control circuit and a pass element, and wherein the power module further comprises a voltage sense circuit configured to provide a feedback signal to the driver controller representative of a voltage across the pass element, wherein, upon the occurrence of a short circuit in the at least one channel, the adjustment signal is provided in response to the feedback signal to reduce the output voltage.

4. The system of claim 3, wherein upon the removal of the short circuit, the adjustment signal is provided in response to the feedback signal to increase the output voltage.

5. The system of claim 1, wherein the linear regulator comprises a current control circuit and a pass element, and wherein the power module further comprises a short circuit protection circuit configured to disable the pass element in response to a short circuit in the at least one channel.

6. The system of claim 5, wherein the power module further comprises a voltage sense circuit configured to provide a feedback signal to the driver controller

representative of a voltage across the pass element, wherein, in response to the short circuit, the adjustment signal is provided in response to the feedback signal to reduce the output voltage.

7. The system of claim 6, wherein upon the removal of the short circuit, the adjustment signal is provided in response to the feedback signal to increase the output voltage.

8. The system of claim 1, wherein the driver controller is configured to provide an offset signal to the linear regulator to reduce the drive current to approximately zero.

9. The system of claim 1, wherein the linear regulator comprises a current control circuit and a pass element, and wherein the power module further comprises a voltage sense circuit configured to provide a feedback signal to the driver controller

representative of a voltage across the pass element, and wherein the driver controller is configured to determine an operating mode of the driver in response to the reference signal and the feedback signal.

10. A method of controlling a tunable light source including a tunable lighting module having at least one channel including at least one solid-state light source, the method comprising:

coupling an output of a DC-DC regulator to at least one channel of the tunable lighting module;

coupling the at least one channel to a linear regulator to provide a constant current

through the at least one channel;

receiving a command from a switch module to adjust a light output of the at least one channel to a desired setting;

adjusting the constant current through the at least one channel in response to the

command using a reference signal applied to a linear regulator;

sensing a voltage across a pass element of the linear regulator;

determining an adjustment voltage in response to the voltage across the pass element; and coupling the adjustment voltage to the DC-DC regulator to adjust the output in response to the voltage across the pass element.

11. The method of claim 10, wherein the coupling the adjustment voltage to the DC- DC regulator to adjust the output in response to the voltage across the pass element comprises adjusting the output to maintain a voltage across a pass element of the linear regulator at a desired voltage.

12. The method of claim 10, wherein the coupling the adjustment voltage to the DC- DC regulator to adjust the output in response to the voltage across the pass element comprises adjusting the output to reduce the output voltage in response to a short circuit in the at least one channel.

13. The method of claim 10, wherein the coupling the adjustment voltage to the DC- DC regulator to adjust the output in response to the voltage across the pass element comprises adjusting the output to increase the output voltage in response to removal of a short circuit in the at least one channel.

14. The method of claim 10, further comprising disabling the pass element in response to a short circuit in the at least one channel.

15. The method of claim 10, further comprising determining an operating mode of the driver in response to the reference signal and the voltage across the pass element.

16. A system for controlling a tunable light source, the system comprising:

a tunable lighting module including a plurality of channels, each of the plurality of

channels being configured to provide light output having a different associated correlated color temperature (CCT);

a switch module configured to provide at least one command representative of a desired CCT of a blended light output of the plurality of channels; and

a driver coupled to the switch module and configured to receive the at least one

command, the driver configured to calculate the lumens required to drive each of the plurality of channels to achieve the desired CCT and to calculate an associated drive current for each of the plurality of channels based on the calculated lumens required to drive each of the plurality of channels to achieve the desired CCT, the driver configured to drive each of the plurality of channels with the associated drive current.

17. A system according to claim 16, wherein the driver is configured to calculate the lumens required to drive each channel in response to receiving the command using parameters associated with the tunable light source.

18. A system according to claim 16, wherein the driver is configured to calculate the associated drive current using parameters associated with the tunable light source.

19. A system according to claim 18, wherein the parameters include a plurality of parameters selected from the group consisting of: a number of channels in the tunable lighting module, a number of solid state light sources in each of the channels of the tunable lighting module, a maximum flux associated with each of the channels of the tunable lighting module, and color coordinates of each of the channels of the tunable lighting module.

20. A system according to claim 19, wherein the light output of a first one of the plurality of channels has a CCT between about 2600 K and 4000 K and the light output of a second one of the channels has a CCT between about 6600 K and 8000 K.

21. A method for controlling light source including a tunable lighting module including a plurality of channels, each of the plurality of channels being configured to provide light output having a different associated correlated color temperature (CCT), the method comprising:

receiving a command representative of a desired CCT of a blended output of the plurality of channels;

calculating lumens required to drive each of the plurality of channels to provide a light output from the plurality of channels corresponding to the desired CCT; and calculating an associated drive current for each of the plurality of channels based on the calculated lumens required to drive each of the plurality of channels provide a blended light output from the plurality of channels corresponding to the desired CCT.

22. A method according to claim 21, wherein the calculating the lumens comprises calculating lumens required to drive each of the plurality of channels to provide a light output from the plurality of channels corresponding to the desired CCT using parameters associated with the tunable light source.

23. A method according to claim 21, wherein the calculating and associated drive current comprises calculating an associated drive current for each of the plurality of channels based on the calculated lumens required to drive each of the plurality of channels provide the blended light output from the plurality of channels corresponding to the desired CCT using parameters associated with the tunable light source.

24. A method according to claim 23, wherein the parameters include a plurality of parameters selected from the group consisting of: a number of channels in the tunable lighting module, a number of solid state light sources in each of the channels of the tunable lighting module, a maximum flux associated with each of the channels of the tunable lighting module, and color coordinates of each of the channels of the tunable lighting module.

25. A system for controlling a tunable light source, the system comprising:

a plurality of tunable lighting modules coupled to a network;

a plurality of switch modules coupled to the network, each of the switch modules being configured to send commands to one or more of the plurality of tunable lighting modules and the other ones of the plurality of switch modules coupled to the network, each of the switch modules comprising a non-transitory computer- readable memory having instructions stored thereon, which when executed by a switch controller of one of the plurality of the switch modules cause the switch controller to perform a network collision avoidance routine comprising:

determining if a user interface control of the switch module has been activated;

setting all the other of the plurality of switch modules in an inactive state if the user interface control of the switch module has been activated;

sending one of the commands associated with activation of the user interface control; and setting all of the other plurality of switch modules in an active state after sending the one of the commands.

26. A system according to claim 25, wherein the routine further comprises processing one of the commands to determine if the command is to set the switch module in an inactive or active state.

27. A system according to claim 25, wherein the routine further comprises determining if a network collision occurred after the determining if a user interface control of the switch module has been activated and before the setting all the other of the plurality of switch modules in an inactive state if the user interface control of the switch module has been activated.

28. A method for avoiding network collisions in a network including a plurality of tunable light sources and a plurality of switch modules, the method comprising:

determining if a user interface control of one of the switch modules has been activated;

setting all the other of the plurality of switch modules in an inactive state if the user interface control of the one of the switch modules has been activated;

sending a command to one of the tunable light sources associated with activation of the user interface control; and

setting all of the other plurality of switch modules in an active state after sending the one of the commands.

29. A method according to claim 28, wherein the method further comprises processing a first command received by the one of the switch modules to determine if the first command is to set the switch module in an inactive or active state.

30. A method according to claim 28, wherein the method further comprises determining if a network collision occurred after the determining if a user interface control one of the switch module has been activated and before setting all the other of the plurality of switch modules in an inactive state if the user interface control of the one of the switch modules has been activated.