Systems, methods, and devices for forming a user-defined spectral output power distribution

Abstract

A method (400) for operating a lighting fixture (130-145) having multiple light sources at a target chromaticity (320) with a target spectral output power distribution (324), the method comprising: Determining a first distance between the target chromaticity (320) and a first chromaticity (312A) having a first spectral power distribution (404); Determining a second distance between the target chromaticity (320) and a second chromaticity (312B) having a second spectral power distribution (408); Scaling the first spectral power distribution with a first scaling factor to arrive at a first scaled spectral power distribution, the first scaling factor being based on the first distance (412); Scaling the second spectral power distribution with a second scaling factor to arrive at a second scaled spectral power distribution, the second scaling factor being based on the second distance (416); Adding the first scaled spectral power distribution and the second scaled spectral power distribution to achieve (420, 422) the target spectral output power distribution (324) at the target chromaticity (320); and Driving the plurality of light sources at intensities corresponding (424) to the target spectral output power distribution (324).

Description

AREA

[0001] Embodiments described herein relate to controlling the spectral content of an output of a lighting fixture. SUMMARY

[0002] Luminaires or lighting fixtures are capable of producing a wide range of colors by combining light from multiple light sources. A common method for visualizing the color palette of a lighting fixture is to use the International Commission on Illumination's ("CIE") 1931 color space chromaticity diagram. The 1931 CIE color space chromaticity diagram is a two-dimensional representation of the colors in the visible spectrum, in which each color is identified by an xy coordinate (i.e., [x, y]). While the chromaticity of a color can be defined with respect to an xy coordinate, a y tristimulus value is used as a measure of lightness or luminance, yielding the CIE xyY color space.

[0003] The use of xy coordinates (or other conventional metrics for conveying color information such as hue-saturation-intensity [“HSI”], red-green-blue [“RGB”], etc.) to identify colors provides a consistent technique for selecting the color outputs of luminaires or lighting fixtures. However, they do not necessarily result in a consistent output spectrum across different lighting fixtures, as the same color can be produced by many different spectra. Therefore, the user is unable to precisely control the spectral content of a lighting fixture's output using color coordinates.

[0004] Methods for driving light sources to achieve a target color as an output of a lighting fixture, as well as for manually controlling the spectral content of the lighting fixture's output, are disclosed, for example, in U.S. Patent No. 8,723,450, the entire contents of which are incorporated herein by reference. A color control methodology (e.g., HSI, RGB, etc.) is used to produce the target or desired color output of the lighting fixture, and then a user is able to manually control the spectral content of the lighting fixture's output by increasing or decreasing the output intensity value of one or more of the light sources. Based on the user's desired change in the spectral content of the lighting fixture's output, a new set of light source output intensity values for maintaining the target color is determined and used to operate the lighting fixture.

[0005] However, conventional control of a lighting fixture's spectral output requires the user to manually and individually increase or decrease the output intensity value of one or more of the light sources. An unfamiliar user may not understand which spectral content needs to be adjusted in the lighting fixture to achieve a desired effect. For example, lighting designers are familiar with using conventional filters (e.g., color filters, gel filters, dichroic glass filters, etc.) to create an output color with a specific spectral power distribution from a particular light source, but would not know how to create a new color with a spectral power distribution similar to that of the conventional filter from a different light source.

[0006] Conventional filters are attached to the output end of a lighting fixture and absorb or reflect some wavelengths of light while transmitting other wavelengths of light emitted by a light source (e.g., an incandescent lamp). The light passing through the filter provides an output beam from the lighting fixture with a specific spectral composition. Using such filters, several hundred different colors can be provided, and certain filter colors have become widely accepted as standard colors in the industry. However, the use of such physical filters is inefficient because the process of filtering out wavelengths is subtractive, and the absorption of unselected wavelengths generates heat as lost energy.The replacement of incandescent and gas-discharge lamps with light-emitting diodes (LEDs) has provided an alternative to color filters, as a desired color can instead be created by providing electrical power in selected amounts to different colored LEDs within the lighting fixture, with the final color being produced by additive mixing. Methods for matching an LED lighting fixture output to a reference filter color are disclosed, for example, in U.S. Patent No. 6,683,423, the entire contents of which are incorporated herein by reference.

[0007] Additionally, users often prefer to work with filters from a particular manufacturer (e.g., within a filter family). While this is sometimes due to convenience or habit, there may also be a spectral purpose. For example, a particular "filter family" may share certain desirable spectral similarities, whether by design or by the nature of its manufacturing process. Even in cases where multiple manufacturers offer filters that would nominally produce identical chromaticity values, the spectra used to achieve those chromaticity values can vary widely.

[0008] Furthermore, conventional control techniques do not provide a way to drive a lighting fixture output at a desired color with a spectral content (i.e., a spectral power distribution) similar to other known spectral power distributions. For example, a lighting designer is familiar with an industry-standard green filter that produces a green color with a particular spectral power distribution. The lighting designer may want to select a different green color variation (e.g., a lime green) while retaining as many similarities as possible to the well-known green filter. This new color (lime green) may be produced by the lighting fixture with several different spectral power distributions (i.e., metamer control), but the lighting designer does not know how to produce the new color while maintaining the characteristics of a known spectral power distribution.In particular, one feature the lighting designer may want to replicate from a known filter is the "feel" of a color, or how the light output of the luminaire appears to an observer on an object. The observer's "feel" or perception of an object illuminated by a luminaire output is determined at least in part by the spectral power distribution of the luminaire's light output.

[0009] US 2010 / 0 188 022 A1 relates to methods, luminaires, and systems for adapting a composite light spectrum to a target light spectrum. US 2012 / 0 081 010 A1 relates to systems and methods for controlling the power of a luminaire. US 2016 / 0 360 591 A1 relates to methods for color-tuning a multicolor LED-based lighting device. US 2012 / 0 176 063 A1 relates to systems and methods for controlling the power of a lighting installation.

[0010] The invention relates to methods according to claims 1, 15, and 18. Advantageous embodiments are defined in the subclaims. Methods described herein provide for operating a lighting fixture having multiple light sources at a target chromaticity with a target spectral output power distribution. The methods include determining a first distance between the target chromaticity and a first chromaticity with a first spectral power distribution, determining a second distance between the target chromaticity and a second chromaticity with a second spectral power distribution, and scaling the first spectral power distribution with a first scaling factor to arrive at a first scaled spectral power distribution. The first scaling factor is based on the first distance.The methods also include scaling the second spectral power distribution with a second scaling factor to arrive at a second scaled spectral power distribution. The second scaling factor is based on the second distance. The methods also include summing the first scaled spectral power distribution and the second scaled spectral power distribution to achieve the target spectral output power distribution at the target chromaticity, and driving the plurality of light sources at intensities corresponding to the target spectral output power distribution.

[0011] In some aspects, the first distance is measured between MacAdam ellipses corresponding to the target chromaticity and the first chromaticity in the 1931 CIE xy color space.

[0012] In some aspects, the first distance is the Euclidean distance between the target chromaticity and the first chromaticity in the CIE 1960 UV color space.

[0013] In some aspects, the first distance is the ΔE between the target chromaticity and the first chromaticity in the CIE L*a*b* color space.

[0014] In some aspects, the first distance is the sum of the absolute difference between the Cartesian coordinates of the target chromaticity and the first chromaticity.

[0015] In some aspects, the first scaling factor is based on user preference.

[0016] In some aspects, the user preference is an amount of a waveband in the output of the spectral power distribution.

[0017] In some aspects, the first scaling factor is based on a weighting function.

[0018] In some aspects, the weighting function is a polynomial function.

[0019] In some aspects, the weighting function is an exponential or logarithmic function.

[0020] In some aspects, the first chromaticity with the first spectral power distribution corresponds to the chromaticity and the spectral power distribution resulting from the use of a filter in front of a luminous source.

[0021] In some aspects, the first chromaticity with the first spectral power distribution corresponds to the chromaticity and spectral power distribution of a tungsten lamp.

[0022] In some aspects, the first chromaticity having the first spectral power distribution corresponds to a spectral power distribution created by the user.

[0023] In some aspects, the first chromaticity with the first spectral power distribution corresponds to a physical emission spectrum.

[0024] Methods described herein provide for operating a lighting fixture having multiple light sources at a target chromaticity with a target spectral output power distribution. The methods include multiplying a first spectral power distribution by a second spectral power distribution to determine a spectral power distribution product, multiplying the spectral power distribution product by a spectral power distribution of a light source to determine the target spectral output power distribution at the target chromaticity, and driving the multiple light sources at intensities corresponding to the target spectral output power distribution.

[0025] In some aspects, the spectral power distribution of the product corresponds to the spectral power distribution resulting from a combination of at least two filters in front of a light source.

[0026] In some aspects, the spectral power distribution of the lamp corresponds to the spectral power distribution of a tungsten lamp.

[0027] Methods described herein provide for operating a lighting fixture having multiple light sources at a target chromaticity with a target spectral output power distribution. The methods include raising a first spectral power distribution to an exponential power to determine an exponential spectral power distribution, multiplying the exponential spectral power distribution by a spectral power distribution of a light source to determine the target spectral output power distribution at the target chromaticity, and driving the multiple light sources at intensities corresponding to the target spectral output power distribution.

[0028] In some aspects, the exponent corresponds to an opacity selected by the user.

[0029] In some aspects, the opacity selected by the user is a negative value.

[0030] In some aspects, the spectral power distribution of the lamp corresponds to the spectral power distribution of a tungsten lamp.

[0031] Before embodiments are explained in detail, it is to be understood that the embodiments are not limited in their application to the details of the configuration and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The embodiments may be practiced or carried out in various ways. It is also to be understood that the phraseology and terminology used herein are for the purpose of description and should not be considered limiting. The use of "including," "comprising," or "having," and variations thereof, is intended to include the elements listed thereafter and equivalents thereof, as well as additional elements.Unless otherwise specified or limited, the terms "mounted", "connected", "supported" and "coupled" and variations thereof are used broadly and include both direct and indirect mountings, connections, supports and couplings.

[0032] Additionally, it should be understood that embodiments may include hardware, software, and electronic components or modules, which for purposes of discussion may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, given this detailed description, would recognize that in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and / or application-specific integrated circuits ("ASICs"). Therefore, it should be noted that multiple hardware- and software-based devices, as well as multiple different structural components, may be utilized to implement the embodiments.For example, “servers” and “computing devices” as described in the patent specification may include one or more processing units, one or more computer-readable media modules, one or more input / output interfaces, and various connections (e.g., a system bus) connecting the components.

[0033] Other aspects of the embodiments will become apparent from the detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a lighting system for controlling one or more LED lighting fixtures according to embodiments described herein. Fig. 2 is a block diagram of a luminaire control system for the luminaire of Fig. 1. Fig. 3 is a perspective view of a lighting fixture with an LED light source. Fig. Figure 4 is a diagram of the 1931 CIE color space illustrating reference chromaticities and a target chromaticity. Fig. Figure 5 is a diagram of spectral power distributions for the reference chromaticities of Fig. 4. Fig. Figure 6 illustrates distances between reference chromaticities and a target chromaticity in a generalized color space. Fig. 7 is a flowchart of a method for determining a target spectral power distribution. Fig. Figure 8 is a diagram of two reference spectral power distributions and an interpolated spectral power distribution based on the two reference spectral power distributions. Fig. 9 is a flowchart of a method for determining a target spectral power distribution. Fig. Figure 10 is a diagram of two reference spectral power distributions and a multiplicative spectral power distribution based on the two reference spectral power distributions. Fig. Figure 11 is a graphic representation of the 1931 CIE color space, illustrating a chromaticity and various transparency variants thereof. Fig. 12 is a diagram of spectral power distributions of chromaticity and different transparency variants of Fig. 11. Fig. 13 is a flowchart of a method for determining a target spectral power distribution. DETAILED DESCRIPTION

[0034] Fig. 1 illustrates a lighting system 100 for controlling multiple LED lighting fixtures. The system 100 includes a plurality of user input devices 105-120, a control board or panel 125, a first lighting fixture 130, a second lighting fixture 135, a third lighting fixture 140, a fourth lighting fixture 145, a database 150, a network 155, and a server-side mainframe computer or server 160. The plurality of user input devices 105-120 include, for example, a personal or desktop computer 105, a laptop computer 110, a tablet computer 115, and a mobile phone (e.g., a smartphone) 120.

[0035] Each of the devices 105-120 is configured to establish a communicative connection with the server 160 via the network 155 and to provide or receive information from the server 160 related to the control or operation of the system 100. Each of the devices 105-120 is also configured to establish a communicative connection with the control board 125 to provide or receive information from the control board 125. The connections between the user input devices 105-120 and the control board 125 or the network 155 are, for example, wired connections, wireless connections, or a combination of wireless and wired connections.Similarly, the connections between the server 160 and the network 155 or the control board 125 and the lighting fixtures 130-145 are wired connections, wireless connections, or a combination of wireless and wired connections.

[0036] The network 155 is, for example, a wide area network (“WAN”) (e.g., a TCP / IP-based network), a local area network (“LAN”), a neighborhood area network (“NAN”), a home area network (“HAN”), or a personal area network (“PAN”) employing any of a variety of communication protocols, such as Wi-Fi, Bluetooth, ZigBee, etc. In some implementations, the network 155 is a cellular network, such as a GSM (Global System for Mobile Communications) network, a GPRS (General Packet Radio Service) network, a Code Division Multiple Access (“CDMA”) network, an EV-DO (Evolution-Data Optimized) network, an EDGE (Enhanced Data Rates for GSM Evolution) network, a 3GSM network, a 4GSM network, a 4G LTE network, a 5G New Radio network, a DECT (Digital Enhanced Cordless Telecommunications) network, a digital AMPS network (“IS-136 / TDMA”) or an iDEN network (Integrated Digital Enhanced Network), etc.In some implementations, network 155 is internal and local to server 160. For example, an integrated system may be provided with a database, memory, keyboard, and controllers. In some embodiments, network connections to lighting fixtures 130-145 may be established using DMX-512 networks.

[0037] Fig. 2 illustrates a controller 200 for the system 100. The controller 200 is electrically and / or communicatively connected to a plurality of modules or components of the system 100. For example, the illustrated controller 200 is connected to one or more displays 205 (e.g., LEDs, a liquid crystal display [“LCD”], etc.), a user input or user interface 210 (e.g., a user interface of the user input device 105-120 in Fig. 1) and a communications interface 215. The controller 200 is also connected to the control board 125. The communications interface 215 is connected to the network 155 to allow the controller 200 to communicate with the server 160. The controller 200 includes combinations of hardware and software operable to, among other things, control the operation of the system 100, control the operation of the lighting fixtures 130-145, communicate via the network 155, communicate with the control board 125, receive input from a user via the user interface 210, provide information to a user via the displays 205, etc.

[0038] In the Fig. 2, the control device 200 would be associated with one of the user input devices 105-120. As a result, the control device 200 is Fig. 2 as being connected to the control board 125, which in turn is connected to the first lighting fixture 130, the second lighting fixture 135, the third lighting fixture 140, and the fourth lighting fixture 145. In other embodiments, the control device 200 is included in the control board 125, and for example, the control device 200 may provide control signals directly to the first lighting fixture 130, the second lighting fixture 135, the third lighting fixture 140, and the fourth lighting fixture 145. In some embodiments, the control device 200 is associated with (e.g., included within) a lighting fixture 130-145.In other embodiments, the controller 200 is associated with the server 160 and communicates via the network 155 to provide control signals to the control board 125 and the first light fixture 130, the second light fixture 135, the third light fixture 140, and the fourth light fixture 145. Spectral power distributions known in the industry or created by a user may be stored on the server 160 and accessed from the server 160.

[0039] The control device 200 includes a plurality of electrical and electronic components that provide power, operational control, and protection for the components and modules within the control device 200 and / or the system 100. For example, the control device 200 includes, among other things, a processing unit 220 (e.g., a microprocessor, a microcontroller, or other suitable programmable device), a memory 225, input units 230, and output units 235. The processing unit 220 includes, among other things, a control unit 240, an arithmetic logic unit (ALU) 245, and a plurality of registers 250 (in Fig. 2 as a group of registers) and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 220, the memory 225, the input units 230 and the output units 235, as well as the various modules or circuits connected to the control device 200, are connected by one or more control and / or data buses (e.g., a common bus 255). The control and / or data buses are shown for illustration in Fig. 2. The use of one or more control and / or data buses for interconnection and communication between the various modules, circuits, and components would be known to those skilled in the art in view of the embodiments described herein.

[0040] The memory 225 is a non-transitory computer-readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area may include combinations of different memory types, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic storage devices. The processing unit 220 is connected to the memory 225 and executes software instructions that may be stored in a RAM of the memory 225 (e.g., during execution), a ROM of the memory 225 (e.g., on a generally permanent basis), or another non-transitory computer-readable medium such as another memory or disk.Software that may be included in the implementation of system 100 and controller 200 may be stored in memory 225 of controller 200. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 200 is configured to, among other things, retrieve and execute instructions from memory 225 relating to the control operations and methods described herein. - method. Spectral power distributions known in the industry or created by a user may be stored in memory 225 and retrieved via memory 225. In other embodiments, controller 200 includes additional, fewer, or different components.

[0041] The user interface 210 is included to provide user control of the system 100 and / or the lighting fixtures 130-145. The user interface 210 is operatively coupled to the controller 200, for example, to control drive signals provided to the lighting fixtures 130-145 and to generate and provide control signals to corresponding drive circuits. The user interface 210 may include any combination of digital and analog input devices required to achieve a desired level of control for the system 100. For example, the user interface 210 may include a computer with a display and input devices, a touch-sensitive screen display, a plurality of knobs, dials, switches, buttons, sliders, or the like. In the Fig. In the embodiment illustrated in Figure 2, the user interface 210 is separate from the control board 125. In other embodiments, the user interface 210 is included within the control board 125. In some embodiments, the user interface 210 is separate from the control system 100 (e.g., as a portable device communicatively connected to the control device 200 wirelessly).

[0042] The controller 200 is configured to operate in combination with the control board 125 to provide direct drive signals to the lighting fixtures 130-145. As described above, in some embodiments, the controller 200 is configured to provide direct drive signals to the lighting fixtures 130-145 without separately interacting with the control board 125 (e.g., the control board 125 includes the controller 200). The direct drive signals provided to the lighting fixtures 130-145 are provided, for example, based on user input received by the controller 200 from the user interface 210.

[0043] As in Fig. 2, the controller 200 is connected to the lighting fixtures 130-145. In some embodiments, each lighting fixture 130-145 includes a chip-on-board ("COB") light source. An embodiment with four lighting fixtures is illustrated for exemplary purposes only. In other embodiments, four or more lighting fixtures are used to further enhance the ability of the lighting system 100 to produce visible light. Conversely, in other implementations, fewer than four lighting fixtures are used (i.e., one or two light modules). In some embodiments, the lighting fixtures 130-145 are light-emitting diode ("LED") lighting fixtures.

[0044] Fig. 3 illustrates a lighting fixture 260 (i.e., a luminaire) that may be used, for example, in entertainment lighting, architectural lighting, etc. The lighting fixture 260 includes a light source 265 that generates light, a mixing assembly 270 that mixes the light, a control port assembly 275 through which the light passes after exiting the mixing assembly 270, and a lens assembly 280 that receives the light from the control port assembly 275 and projects it toward the target or desired location. The light source 265 includes an LED array configured to generate light at multiple wavelengths. The LED array includes a substrate in the form of a circuit board supporting a plurality of LEDs. The plurality of LEDs may, for example, be arranged in an array (e.g., an LED array). In some embodiments, the LED array is hexagonal.It should be understood that the exact type, number, and positioning of the LEDs may be substantially modified without departing from the teachings disclosed herein. For purposes of description herein, the lighting fixture 260 could be any of the lighting fixtures 130-145.

[0045] With reference to Fig. 4, the CIE 1931 color space 300 is illustrated with the Planck locus 304 shown. Furthermore, multiple chromaticities 308 within the color space 300 are illustrated. In some embodiments, each of the multiple chromaticities 308 corresponds to conventional filters that might be used with incandescent lamps. Any number of the chromaticities 308 are selected as reference chromaticities 312. In the illustrated embodiment, there are six reference chromaticities 312. For each of the reference chromaticities 312, there is a corresponding spectral power distribution 316 (see, e.g., Fig. 5). For example, the reference chromaticities 312 include a first chromaticity 312A with a first spectral power distribution 316A, a second chromaticity 312B with a second spectral power distribution 316B, a third chromaticity 312C with a third spectral power distribution 316C, a fourth chromaticity 312D with a fourth spectral power distribution 316D, a fifth chromaticity 312E with a fifth spectral power distribution 316E, and a sixth chromaticity 312F with a sixth spectral power distribution 316F. The reference chromaticities 312 and their corresponding spectral power distributions 316 may be stored in the memory 225 of the controller 200. A target or desired chromaticity 320 (i.e., a target color) is also illustrated in the color space 300.In the illustrated embodiment, the reference chromaticities 312 are the six colors closest to the desired chromaticity 320 in the 1931 xy CIE color space 300. In some embodiments, the desired chromaticity 320 is selected by a user. In other embodiments, the desired chromaticity 320 is automatically selected by the processing unit 220 based on user preferences or settings.

[0046] When the desired chromaticity 320 is displayed or selected, a corresponding desired spectral output power distribution is determined or calculated based on the reference chromaticities 308 and their corresponding spectral power distributions 316. The desired spectral output power distribution for the desired chromaticity 320 is determined based on at least one reference spectral power distribution 316. Several embodiments for determining the desired spectral output power distribution based on at least one reference spectral power distribution are disclosed herein.

[0047] A first method for determining the desired spectral output power distribution based on at least one spectral reference power distribution is an interpolative method. {S⇀n} shall be a set of known spectral power distributions at certain chromaticities 312. See, for example, the reference chromaticities 312 with the reference spectral power distributions S1, S2, S3...S n in Fig. 6. For a target chromaticity 320 selected by the user, the corresponding desired spectral power distribution T⇀ determined by Eq. 1: T⇀=∑i=1nf(di.pi)*S⇀i where d i represents a chromaticity distance, p irepresents a generalized preference parameter determined heuristically or through explicit user interaction, and where f represents a generalized weighting function (e.g., polynomial, power, logarithmic, exponential, etc.). In some embodiments, the generalized preference parameter is based on a user preference. In particular, the user preference may be a desired amount of a particular waveband (e.g., color channel) in the spectral output power distribution.

[0048] With reference to Fig. 6 is the chromaticity distance d i (ie d1, d2, d3...d n ) representative of how far the reference chromaticities 312 are from the target chromaticity 320. The chromaticity distance d ican be calculated using one or more of the following values: MacAdam ellipses in the CIE 1931 xy color space; Euclidean distance in the CIE 1960 UV color space; ΔE* in the L*a*b* color space; the Manhattan distance in a discretized color space (i.e., the Taxi distance, the sum of the absolute difference of the Cartesian coordinates); or another uniquely determined distance in a color space. In some embodiments, the first distance is measured between MacAdam ellipses corresponding to the desired chromaticity and the first chromaticity in the CIE 1931 xy color space. In other embodiments, the first distance is the Euclidean distance between the desired chromaticity and the first chromaticity in the CIE 1960 UV color space. In other embodiments, the first distance is the delta E (ΔE*) between the desired chromaticity and the first chromaticity in the CIE L*a*b* color space.In other embodiments, the first distance is the sum of the absolute difference of the Cartesian coordinates of the desired chromaticity and the first chromaticity.

[0049] The weighting function f is configured to ensure or prioritize one or more of the following: continuity in the target spectrum at different chromaticities; consistency between the target spectrum and various elements of known spectral power distributions at specific chromaticities; or algorithm performance in a particular luminaire.

[0050] The known spectral power distributions {S⇀n}, used in the interpolative method may be different subsets of reference chromaticities 308. For example, in some embodiments, {S⇀n} a subset (true or false) of a family or families of conventional filters known to those skilled in the art, and with a user-configurable illuminant, including, but not limited to, CIE standard illuminants. In other embodiments, {S⇀n} a subset (true or false) of a family or families of previous user-created spectral power distributions stored in advance by the user in memory 225 and retrieved for the present calculation. In still other embodiments, {S⇀n} a subset (true or false) of a family or families of physical emission spectra (e.g., thermal blackbody emission, biological phosphorescence, or spectra of various chemical elements or compounds). As a result, the known spectral power distributions from which the target spectral power distribution is to be interpolated can be the spectral power distributions of filters, tungsten lamps, blackbody radiators, etc.

[0051] Fig. 7 is a method 400 for controlling and operating the lighting fixtures 130-145 at the desired chromaticity 320 with the desired spectral output power distribution, T⇀. The method 400 includes determining a first distance d1 between the desired chromaticity 320 and a first chromaticity 312A having a first spectral power distribution S1 (STEP 404). The method 400 includes determining a second distance d2 between the desired chromaticity 320 and a second chromaticity 312B having a second spectral power distribution S2 (STEP 408). STEP 412 includes scaling the first spectral power distribution S1 with a first scaling factor to arrive at a first scaled spectral power distribution. The first scaling factor is based on the first distance d1. Likewise, STEP 416 includes scaling the second spectral power distribution S2 with a second scaling factor to arrive at a second scaled spectral power distribution. The second scaling factor is based on the second distance d2.In the illustrated embodiments, the scaling in STEP 412 and STEP 416 is performed according to Eq. 1. As such, the first and second scaling factors are determined by the weighting function f of Eq. 1. In STEP 420, the first scaled spectral power distribution and the second scaled spectral power distribution are added (i.e., summed) to obtain a summed spectral power distribution. Next, STEP 422 involves using the summed spectral power distribution and the desired chromaticity 320 to generate a target output spectral power distribution 324. In some embodiments, STEP 422 may involve calculating a spectral power distribution using conventional methods, such as those described in U.S. Patent No. 8,723,450, the entire contents of which are incorporated herein. In other words, using Eq.1 and reference spectral power distributions, the target output spectral distribution power is determined. Referring to . Fig. 8, the target spectral output power distribution 324 is determined from the reference spectral power distributions S1 and S2. Next, STEP 424 involves driving the plurality of light sources (i.e., the plurality of LEDs) within the lighting fixtures 130-145 at power intensities corresponding to the desired spectral output power distribution.

[0052] A second method for determining the desired spectral output power distribution based on at least one reference spectral power distribution is a multiplicative method. {S⇀n} shall be a user-selected set of known spectral transmittances, for example, theater filters, and I⇀ should be a user-configurable light source. The corresponding spectral target power distribution T⇀ is determined by Eq. 2: T⇀=I⇀*∏i=1nS⇀i

[0053] The multiplicative method can be operated to simulate the physical stacking (i.e., "sandwiching") of multiple physical filters. Filter stacking, or a filter sandwich, has traditionally been used to achieve a desired effect by combining more than one physical filter in series at the output of a lighting fixture. The multiplicative method can produce a discrete set of chromaticities (since {S⇀n} is finite). In some embodiments, the multiplication is performed on a wavelength basis. In practice, the number of subsets of {S⇀n} extremely large, therefore the limiting factor becomes the discretization and the addressable color space of the illuminant. In some embodiments, a user can specify a target chromaticity and at least one known spectral transmittance S⇀ and lamps I⇀ and a minimally different spectral target T⇀ calculate.

[0054] Fig. 9 is a method 500 for controlling and operating the lighting fixtures 130-145 at the desired chromaticity with the desired spectral output power distribution. The method 500 includes multiplying a first spectral power distribution 516A (see Fig. 10) with a second spectral power distribution 516B (see Fig. 10) to obtain a spectral power distribution of the product (STEP 504). In some embodiments, the spectral power distribution of the product corresponds to the spectral power distribution resulting from a combination of at least two physical filters (e.g., two gel filters). The method 500 also includes multiplying the spectral power distribution of the product by a spectral power distribution I of the illuminant to obtain the desired spectral output power distribution 528 with the desired chromaticity (STEP 508). In some embodiments, the spectral power distribution of the illuminant corresponds to the spectral power distribution of a tungsten lamp. In some embodiments, STEP 504 and STEP 508 are reversed or combined into a single step corresponding to EQU. 2. Next, at STEP 512, the plurality of light sources (i.e.,of the plurality of LEDs) within the lighting fixtures 130-145 are driven at power intensities corresponding to the desired spectral output power distribution 528.

[0055] A third method for determining the desired spectral output power distribution based on at least one reference spectral power distribution is a logarithmic or exponential method. S⇀ shall be a user-selected spectral transmittance, such as a theatrical filter. For a user-selected opacity (or alternatively optical depth) τ and for a user-configurable illuminant I⇀, the corresponding spectral target power distribution T⇀ determined by Eq. 3: T⇀=I⇀∗S⇀τ

[0056] The third method is configured to simulate different thicknesses (i.e., transparency) of a physical filter. The multiplication and exponentiation are understood to be on a wavelength basis. Although negative opacity is not achievable with a physical filter, such spectral solutions are possible using the third method and Eq. 3. For example, Eq. 3 can determine a spectral output power distribution for a negative opacity. For a user-selected chromaticity, the closest point on the chromaticity locus is determined by varying the opacity τ, and this value is used to generate the target spectrum. T⇀ to be calculated as above. See for example Fig. 11, which illustrates a reference chromaticity 614A and the corresponding transparency or opacity variant chromaticities 620A-620D. In the illustrated embodiment, chromaticity 620A corresponds to 1 / 2 the opacity of chromaticity 614A, and chromaticity 620B corresponds to 1 / 4 the opacity of chromaticity 614A. Likewise, chromaticity 620C corresponds to zero opacity of chromaticity 614A (i.e., chromaticity 620C is located at Planckian locus 304). Furthermore, chromaticity 620D mathematically corresponds to a negative 1 / 4 the opacity of chromaticity 614A. The corresponding spectral power distributions are shown in Fig. 12. In particular, the reference spectral power distribution 616A corresponds to the reference chromaticity 614A, and the target spectral power distributions 632A-632D correspond to the target chromaticities 620A-620D, respectively.

[0057] Fig.13 is a method 600 for controlling and operating the lighting fixtures 130-145 at the desired chromaticity with the desired spectral output power distribution. The method 600 includes raising a first spectral power distribution (e.g., 616A) to an exponential power distribution to arrive at an exponential spectral power distribution (STEP 604). In some embodiments, the exponent corresponds to a user-selected opacity. Additionally, in some embodiments, the user-selected opacity is a negative value. The method 600 also includes multiplying the exponential spectral power distribution by a spectral power distribution I of the light source to obtain the desired spectral output power distribution (e.g., 632A) with the desired chromaticity (e.g., 620A) (STEP 608).In some embodiments, the spectral power distribution of the illuminant corresponds to the spectral power distribution of a tungsten lamp. In some embodiments, STEP 604 and STEP 608 are combined into a single step corresponding to EQU. 3. Next, at STEP 612, the plurality of light sources (i.e., the plurality of LEDs) within the lighting fixtures 130-145 are driven at power intensities corresponding to the desired spectral output power distribution 632A.

[0058] With reference to all three described methods 400, 500, and 600, they provide methods for selecting the spectral content of a light in a controlled manner to alter its performance and visual perception at a given chromaticity. In some embodiments, the controller 200 is adaptive and anticipates the user's preferences as the user selects, calculates, and stores cues, states, or settings across the entire color space. For example, a user may find that they enhance the amber emitter in most cues, states, or settings, perhaps due to the scene, venue, or desired mood or atmosphere. By using the user's existing cues, states, or settings as a subset {S⇀n} For example, in EQ. 1, new cues, states, or settings with different chromaticities can be created, which would automatically contain a similar amber boost.

Claims

[1] A method (400) for operating a lighting fixture (130-145) having multiple light sources at a target chromaticity (320) with a target spectral output power distribution (324), the method comprising: Determining a first distance between the target chromaticity (320) and a first chromaticity (312A) having a first spectral power distribution (404); Determining a second distance between the target chromaticity (320) and a second chromaticity (312B) having a second spectral power distribution (408); scaling the first spectral power distribution with a first scaling factor to arrive at a first scaled spectral power distribution, the first scaling factor being based on the first distance (412); scaling the second spectral power distribution with a second scaling factor to arrive at a second scaled spectral power distribution, the second scaling factor being based on the second distance (416); Adding the first scaled spectral power distribution and the second scaled spectral power distribution to achieve the target spectral output power distribution (324) at the target chromaticity (320) (420, 422); and Driving the plurality of light sources at intensities corresponding (424) to the target spectral output power distribution (324). [2] The method of claim 1, wherein the first distance is measured between MacAdam ellipses corresponding to the target chromaticity (320) and the first chromaticity (312A) in the CIE 1931 xy color space. [3] The method of claim 1, wherein the first distance is the Euclidean distance between the target chromaticity (320) and the first chromaticity (312A) in the CIE 1960 UV color space. [4] The method of claim 1, wherein the first distance is the ΔE between the target chromaticity (320) and the first chromaticity (312A) in the CIE L*a*b* color space. [5] The method of claim 1, wherein the first distance is a sum of an absolute difference of Cartesian coordinates of the target chromaticity (320) and the first chromaticity (312A). [6] The method of claim 1, wherein the first scaling factor is based on a user preference. [7] The method of claim 6, wherein the user preference is an amount of a waveband in the output of the spectral power distribution. [8] The method of claim 1, wherein the first scaling factor is based on a weighting function. [9] The method of claim 8, wherein the weighting function is a polynomial function. [10] The method of claim 8, wherein the weighting function is an exponential or logarithmic function. [11] The method of claim 1, wherein the first chromaticity (312A) with the first spectral power distribution corresponds to a chromaticity and a spectral power distribution resulting from the use of a filter in front of a luminous means. [12] The method of claim 1, wherein the first chromaticity (312A) having the first spectral power distribution corresponds to a chromaticity and a spectral power distribution of a tungsten lamp. [13] The method of claim 1, wherein the first chromaticity (312A) having the first spectral power distribution corresponds to a spectral power distribution created by the user. [14] The method of claim 1, wherein the first chromaticity (312A) having the first spectral power distribution corresponds to a physical emission spectrum. [15] A method (500) for operating a lighting fixture (130-145) having multiple light sources at a target chromaticity with a target spectral output power distribution, the method comprising: Multiplying a first spectral power distribution (516A) by a second spectral power distribution (516B) to determine a spectral power distribution of the product (504); Multiplying the product spectral power distribution by a spectral power distribution of the illuminant to determine the target spectral output power distribution (528) at the target chromaticity (508); and Driving the plurality of light sources at intensities corresponding to the target spectral output power distribution (528) (512). [16] The method of claim 15, wherein the spectral power distribution of the product corresponds to the spectral power distribution resulting from a combination of at least two filters in front of a luminous means. [17] Method according to claim 15, wherein the spectral power distribution of the luminous means corresponds to the spectral power distribution of a tungsten lamp. [18] A method (600) for operating a lighting fixture (130-145) having multiple light sources at a target chromaticity with a target spectral output power distribution, the method comprising: Raising a first spectral power distribution (616A) to an exponent to determine an exponential spectral power distribution (604); Multiplying the exponential spectral power distribution by a spectral power distribution of the illuminant to determine (608) the target spectral output power distribution (632A) at the target chromaticity (620A); and Driving the plurality of light sources at intensities corresponding to the target spectral output power distribution (632A) (612). [19] The method of claim 18, wherein the exponent corresponds to an opacity selected by the user. [20] The method of claim 19, wherein the opacity selected by the user is a negative value. [21] The method according to claim 18, wherein the spectral power distribution of the luminous means corresponds to the spectral power distribution of a tungsten lamp.

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