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WO2008139369A1 - Dispositif d'éclairage avec une pluralité d'émetteurs de lumière - Google Patents

Dispositif d'éclairage avec une pluralité d'émetteurs de lumière Download PDF

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Publication number
WO2008139369A1
WO2008139369A1 PCT/IB2008/051753 IB2008051753W WO2008139369A1 WO 2008139369 A1 WO2008139369 A1 WO 2008139369A1 IB 2008051753 W IB2008051753 W IB 2008051753W WO 2008139369 A1 WO2008139369 A1 WO 2008139369A1
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WO
WIPO (PCT)
Prior art keywords
lighting device
light emitters
color
control
controller
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Application number
PCT/IB2008/051753
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English (en)
Inventor
Bernd Ackermann
Peter H. F. Deurenberg
Gerardus H. F. W. Steenbruggen
Wido Van Duijneveldt
Original Assignee
Philips Intellectual Property & Standards Gmbh
Koninklijke Philips Electronics N. V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Philips Intellectual Property & Standards Gmbh, Koninklijke Philips Electronics N. V. filed Critical Philips Intellectual Property & Standards Gmbh
Publication of WO2008139369A1 publication Critical patent/WO2008139369A1/fr

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H05B45/22—Controlling the colour of the light using optical feedback
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H05B45/28—Controlling the colour of the light using temperature feedback

Definitions

  • the invention relates to a lighting device with a plurality of light emitters, particularly LEDs, and means for controlling the light emitters individually according to given target values.
  • a lighting device comprising red, green and blue light emitting diodes (LEDs) is known, wherein the LEDs are controlled in a feedback loop such that given target tristimulus values are optimally matched.
  • LEDs red, green and blue light emitting diodes
  • the lighting device comprises the following components: a) A number N > 2 of light emitters with different primary colors, i.e. with different emission spectra under comparable operating conditions (temperature, driving currents, etc). Each light emitter may be a single lamp or a combination of several, identical or distinct lamps. Moreover, it is understood that the light output of the whole lighting device is the superposition of the light output of all its N light emitters. b) A controller for selectively driving the aforementioned light emitters such that a number k > 1 of given target values (e.g. coordinates of a desired color point) are optimally matched by the common light output of the light emitters, wherein at least two different control schemes are applied.
  • a number k > 1 of given target values e.g. coordinates of a desired color point
  • an “optimal match” means that the light output of the lighting device (i) exactly meets the target values, or (ii) approaches said values as close as possible (e.g. approaches a given color point in a predetermined color space with a predetermined metric of color-distances as close as it is possible with the used light emitters).
  • control scheme shall denote any unique algorithm or mathematical equation by which the driving commands for a light emitter can be calculated based on actual input signals (e.g. the target values and measurement signals) and given parameters (e.g. characteristics of the light emitter).
  • Two control schemes are then considered to be different if the associated equations are structurally different (thus a mere difference in parameters would not make the equations different; moreover, it should be noted that the equations shall not comprise a case sensitive branching as this would allow to formally combine completely different control approaches into one single equation). Examples of control schemes will be described in more detail with respect to different embodiments of the invention.
  • the lighting device is characterized in that there are at least two groups of light emitters, wherein each group is associated to another control scheme that is applied to all light emitters of said group.
  • the driving commands of the light emitters of one group are calculated by one equation, while the driving commands of the light emitters of the other group are calculated by a different equation. If there are more primary colors N than target values k, the division of the light emitters into several groups can particularly be done such that the excess degrees of freedom can be handled.
  • the controller of the lighting device comprises a feed forward controller and a feedback controller, wherein one group of light emitters is controlled with a (pure) feed forward control scheme by the feed forward controller, while the other group of light emitters is controlled with a feedback control scheme by the feedback controller.
  • the feedback controller may internally comprise a feed forward component, too, e.g. for providing basic control signals which are fine-tuned in a feedback loop.
  • Said feed forward component may optionally apply the same feed forward algorithm as the feed forward controller does for the other group of light emitters.
  • the lighting device with the feedback controller preferably comprises a sensor that is coupled to said feedback controller and that can determine the brightness and/or the color point of the common light output of the (active) light emitters.
  • the sensor thus measures important characteristic values of the common light output which are often also (directly or indirectly) specified as target values.
  • the mentioned feed forward controller may be designed in many different ways.
  • the color rendering properties particularly the color rendering index (CRI), and/or the power efficiency of the lighting device.
  • CRI color rendering index
  • target values can be optimized offline using for example a model of the lamp or experiments.
  • the theoretical optimum for target values like CRI and efficiency is therefore preferably used in the feed forward controller to reduce the control problem to a number and kind of control parameters and target values that can be easily handled.
  • These remaining control parameters and target values e.g. brightness and/or color point, are then dealt with in the feedback controller.
  • the mentioned feedback controller is preferably coupled with the feed forward controller in such a way that the target signal and/or the feedback signal which is provided to the feedback controller are freed from components that are already handled by the feed forward controller.
  • the target signals that are provided to the feedback controller should be the difference between the basic target values and that part of the basic target values that is already achieved by the feed forward control.
  • the feedback signal that reports the actual state of the control system to the feedback controller should be the overall measurement signals minus the components of these signals that are caused by the feed forward control loop. The feedback controller can thus be focused on that part of the control task that still remains to be solved after the feed forward control has been done.
  • the driving commands are at least temporarily coupled by a static relation (and accordingly another group of light emitters for which the driving commands are uncoupled or coupled by a different static relation).
  • the static relation allows to calculate the driving commands of all light emitters of said group from the driving command of only one light emitter of the group.
  • the static relation therefore freezes the degrees of freedom of the considered light emitters, thus simplifying the control problem significantly.
  • the driving commands of all light emitters of the group preferably have a fixed ratio with respect to each other. In particular, all driving commands may have the same value or the ratios are chosen such that combined with a subsequent higher level control it results in optimum color rendering properties and/or power efficiency of the lighting device.
  • all light emitters of the considered group i.e. the driving commands of which are coupled by a static relation
  • the higher level control scheme may then simply treat real light emitters and the virtual light emitter (which consists of several real light emitters) structurally in the same way.
  • the higher level control scheme may particularly be designed such that it optimizes brightness and/or color point of the lighting device.
  • the aforementioned higher level controller may optionally provide a feed forward control of all light emitters based on at least some of the target values, e.g. brightness and color point. Moreover, the feed forward control may be based on operating parameters of the lighting device, for example on its temperature.
  • a straightforward feed forward control (e.g. by matrix multiplication) is often available if the control problem is well-defined, i.e. if there are no excess degrees of freedom. This condition can be achieved by the proposed "freezing" of several degrees of freedom with a static relation.
  • the aforementioned higher level feed forward control scheme may further be complemented by a feedback controller acting on at least some of the light emitters. Said feedback control may operate independently of the higher level control scheme, i.e. control different light emitters, or it may operate in cooperation with the higher level control scheme and for example fine-tune its feed forward commands.
  • a second basic variant to realize a lighting device with different control schemes will be described, wherein it should be noted that all described embodiments of the invention can be combined.
  • the individual light emitters are therefore treated similarly at a given point in time, but this treatment may structurally change if other operating conditions are reached.
  • the "operating conditions” may for example comprise the target values, the driving commands of the light emitters, the actual light output of the lighting device, environmental conditions like temperature and/or any other parameter that has an influence on the operation of the lighting device.
  • any kind of control scheme may be applied in the first and the second region of operating conditions, respectively, for example feed forward vs. feedback control or an individual vs. a lumped control of several light emitters (cf. discussion above).
  • the control schemes applied in the first and the second region of operating conditions, respectively differ in the optimization criteria for the common light output of the light emitters that are pursued. This allows to further improve the control of the lighting device as a situation-dependent optimization can be realized.
  • the optimization of the color rendering properties is given priority in the first region of operating conditions.
  • the color rendering properties can for example be quantified by the color rendering index and describe the capability of a light source to reproduce the colors of various objects.
  • the optimization of the color rendering properties may not be the sole optimization criterion, however the one that receives the largest weight in a weighted combination of optimization criteria.
  • the optimization of the lumen output can be given priority in the second region of operating conditions.
  • control scheme changes continuously in an intermediate region of operating conditions between the first and the second region of operating conditions.
  • a continuous transition between the different control schemes can be achieved.
  • the first region of operating conditions may particularly comprise the black-body line of the common (target or actual) light output of the light emitters.
  • the black-body line represents the color points of a radiating black-body at different temperatures and is particularly important for the generation of white light.
  • the second region of operating conditions may accordingly comprise all color points of the common (target or actual) light output of the light emitters that have more than a predetermined distance from the black-body line.
  • At least some of the light emitters may be controlled with a feedback control scheme by a feedback controller.
  • a feedback control allows to match the target values in spite of temperature changes, aging of the light emitters and the like.
  • the controller of the lighting device optionally comprises a memory in which a look-up-table is stored that contains control parameters, especially for a feed forward control.
  • a look-up-table allows a real-time implementation of complex control schemes, for example an optimization of the color rendering index, wherein intermediate values may be determined by a simple interpolation.
  • the light emitters may in principle be any kind of lamp (or group of lamps), it is preferred that they comprise LEDs, phosphor converted LEDs, organic LEDs (OLEDs), LASERs, phosphor converted LASERs, colored fluorescent lamps, filtered (colored) halogen lamps, filtered (colored) high intensity discharge (HID) lamps, and/or filtered (colored) Ultra High Performance (UHP) lamps.
  • LEDs phosphor converted LEDs
  • OLEDs organic LEDs
  • LASERs phosphor converted LASERs
  • colored fluorescent lamps filtered (colored) halogen lamps
  • HID high intensity discharge
  • UHP Ultra High Performance
  • the target values may particularly comprise the color point, the brightness, the color rendering index and/or the power efficiency of the lighting device, wherein this list is far from complete.
  • Figure 1 illustrates the chromaticity diagram relating to a lighting device with five primary colors
  • Figure 2 shows equations relating to a state of the art general feedback control loop
  • Figure 3 shows a block diagram of a state of the art general feedback control loop
  • Figure 4 shows equations relating to a first control approach according to the present invention which comprises both a feed forward and a feedback control
  • Figure 5 shows a block diagram of the first control approach
  • Figure 6 shows equations relating to a second control approach according to the present invention which comprises the lumping together of several light emitters
  • Figures 7 and 8 show two variants of the feed forward control according to the second control approach combined with a feedback control
  • Figure 9 shows diagrams comparing the flux and the CRI of a lighting device when being controlled according to different optimization criteria (left/right) and at different temperatures (upper/lower);
  • Figure 10 shows an example of a look-up-table of duty cycles for color points on the black-body line for a third control approach according to the present invention which comprises situation-dependent optimization criteria;
  • Figure 11 is a flow chart of the generation of a look-up-table for a CRI optimization
  • Figure 12 summarizes in principal drawings the three described control approaches according to the present invention.
  • LED lighting devices based on additive color mixing have high efficiencies, high color rendering indices (CRI), adjustable color temperature, and allow for controlling the color of the light.
  • CRI color rendering indices
  • known lighting devices are equipped with three primary colors (typically red, green and blue: RGB). With these colors, it is possible to generate warm and cool white light (e.g. from 2500 Kelvin to 6500 Kelvin on the black-body locus).
  • CRI > 80 This can partly be solved by replacing red LEDs by amber LEDs, but this only increases the R a whereas the Rg is decreased (Rg shows the lamp's ability to render red objects, cf.
  • the known three-color LED source has three degrees of freedom, which are all restricted by the chosen color point (e.g. x, y coordinates) and brightness, whereas the fourth degree of freedom, introduced by adding e.g. an amber LED, is still open for restriction. Furthermore, it has to be observed that the optical characteristics of LEDs vary with manufacturing spread, aging, temperature and forward current. Therefore, the target color point and brightness can hardly be obtained without a suitable feedback system.
  • the US 6 441 558 Bl describes a system for controlling the color point and brightness of a LED lamp with three primary colors which uses a lumen- feedback and temperature-feed forward control.
  • the system requires switching-off the LEDs briefly for light measurements. Therefore, the LED drivers must have fast response times.
  • a PWM driving method is required to overcome the LED variations with forward current. With the PWM control, the implementation becomes complex and, in addition, the LEDs are not utilized to their full capacity.
  • different control approaches according to the present invention are described that are based on the application of at least two different control schemes and that are particularly suited for the control of lighting devices with more than three primary colors. 1.
  • feedback control is applied to 3 colors and feed forward control is applied to the residual N-3 colors.
  • the tristimulus values of the light of the LED lamp are measured and the control signals for the 3 colors are determined from the measured tristimulus values and the target tristimulus values in a feedback controller.
  • the control signals for the N-3 colors are set such as to achieve as good as possible good color rendering and high efficiency of the lighting device. This concept will be explained in more detail in the following with reference to Figures 1 to 5.
  • Figure 1 illustrates in a CIE chromaticity diagram the situation that the light of five LEDs with color points Pi, P 2 , P3, P4, and P5 shall be mixed to obtain light with color point P x .
  • the color points have been drawn such that Pi corresponds to red, P 2 corresponds to amber, P 3 corresponds to green, P 4 corresponds to cyan, and P 5 corresponds to blue.
  • the light to be emitted by the LED lamp may be specified by its chromaticity coordinates x and y and its luminous flux ⁇ ium- From these quantities, the tristimulus values X, Y, and Z can be calculated according to equations (2.1) of Figure 2.
  • the tristimulus values are grouped into a vector TV ("Tristimulus Values"), wherein it has to be distinguished between the tristimulus values TV 0 of the light perceived by the observer, i.e. a person looking at the LED lamp or an object illuminated by it, and the tristimulus values TV S determined in the feedback path of the color control system.
  • the color sensor used in the lighting device should sense the tristimulus values directly. However, this will not be achieved in practice.
  • the values R, G, and B sensed actually by the color sensor are grouped into a vector SR ("Sensor Readings").
  • control signals for the drivers for the red, green, and blue LEDs will also be grouped into a vector CS ⁇ ("Control Signals"). These may be duty cycles for a pulse width modulation control or current amplitudes for an amplitude modulation control.
  • the mentioned vectors TV, SR, and CS ⁇ are listed in equations (2.2).
  • Figure 3 shows the general setup of a LED color control system for a lamp mixing three primary colors that uses a color sensor. It is indicated where the signals discussed above occur in the system.
  • the input signal TVset and the error signal TV e rr are indicated in addition to the output signals TV 0 and TVs.
  • the transfer functions depicted in the block diagram represent the following parts of the system:
  • Goso - optical system from LEDs to observer
  • Goss - optical system from LEDs to sensor
  • the parts of the control system can be grouped into modules for which the transfer function can be easily determined in a calibration procedure.
  • the first module corresponds to the transfer function G:c2 ⁇ from the control signals CS ⁇ to the tristimulus values TV 0 perceived by the human eye, cf. equation (2.3).
  • the second module corresponds to the transfer function Gic2s from the control signals CS ⁇ to the sensor readings SR, cf. equation (2.4).
  • the calibration matrix Q CAL can be determined from the requirement that the tristimulus values TV S in the feedback path have to be equal to the tristimulus values TVo perceived by the observer, cf. equation (2.5).
  • the block diagram of Figure 3 further indicates that the tristimulus values determined in the feedback path of the system are linked to the sensor readings by the calibration matrix, which results in equation (2.6). If the light of more than three primary colors is mixed, then there are still three tristimulus values grouped into TV and three sensor readings grouped into SR. However, there are now more control signals. For the example considered with 5 primary colors there are 5 control signals, one for each of the primary colors red, amber, green, cyan, and blue. These are grouped into a vector CS ⁇ that has now 5 elements (cf. equation (4.1) of Figure 4.
  • CSfF the vector CSfF of the control signals for the primary colors that are under feed forward control
  • CSfh the vector CSfh of the control signals for the primary colors that are under feedback control.
  • CSfF has N-3 elements, for the example considered it has 2 elements.
  • CSfh has 3 elements, cf. equation (4.1)
  • the transfer functions Gic2 ⁇ and Gic2s from the control signals to the tristimulus values and sensor readings, respectively, are determined in a calibration procedure. N measurements are taken, i.e. 5 for the example considered.
  • Figure 5 shows the simplified block diagram of the resulting LED color control system for a lamp mixing more than three primary colors that uses a color sensor.
  • the transfer function G ⁇ 2c describes how to determine the control signals for the primary colors that are under feed forward control from the tristimulus values of the target color and brightness. Any suitable approach can be used for this feed forward part.
  • the node X of the system has the effect that (i) the theoretically achieved feed forward component Gc2 ⁇ ,ff -CSfF of the resulting tristimulus vector is subtracted from the target and
  • the measured feed forward component GCAL • Qc 2 s,ff • CSfF of the resulting tristimulus vector is subtracted from the tristimulus vector TV S that is used in the feedback path.
  • the same sensor can be used for measuring both the complete light output SR and the feed forward component if the feed forward component is not measured continuously.
  • the feedback controller Gc for the control system for more than three primary colors can be designed in the same way as that for a control system for three primary colors, for example in the way known from the US 6 507 159 Bl.
  • This document (which is incorporated into the present text by reference) describes a method for controlling the color of a LED lamp that mixes the light of three primary colors (usually RGB), wherein a color sensor is used to measure the tristimulus values of the mixed light.
  • Said color sensor comprises three light sensors with peak sensitivity in different parts of the visible spectrum (usually also RGB).
  • the described example discloses a methodology for controlling the target color point and brightness of the mixed light of a LED lamp using N > 3 primary colors.
  • feed forward control is applied to N-3 colors and feedback control is applied to 3 colors.
  • the control signals for the N-3 colors are set such as to achieve as good as possible the predetermined color rendering, efficiency, and tristimulus values.
  • the feedback control the 3 tristimulus values of the light of the LED lamp are measured and the control signals for the 3 colors are determined in a controller from the measured tristimulus values and the tristimulus values of the target color.
  • a typical RGBA LED system would then have for example three degrees of freedom instead of the usual four.
  • This reduction can be achieved by temporarily merging two (or more) degrees of freedom, consequently allowing a simple algorithm to determine the power ratios at which to drive the LEDs.
  • the merged colors are driven at identical ratios.
  • This approach has two important advantages: a microcontroller can determine the required power ratios for every target color point online; the algorithm also yields an optimum in lumen output of the lighting device when it is supplied with the available lumens of each color at the present operating temperature.
  • optical data e.g. X, Y, Z tristimulus values, x, y, L color coordinates and lumen output
  • optical data e.g. X, Y, Z tristimulus values, x, y, L color coordinates and lumen output
  • the C-matrix contains the CIE 1931 tristimulus values for each LED color (X 1 , Y 1 , Z 1 ) on a column basis.
  • the inverse of the C-matrix also called "Calibration matrix" can be used to determine the required duty cycles for a certain target color point. For any three color (LED) system, this can be applied straightforward.
  • the described approach results in a maximum lumen output of the unit at the chosen color point for the temperature the above C-matrix is valid at. Updating the matrix for other temperatures, results then in maximum lumen output at all temperatures.
  • the matrix updating can be accomplished by multiple calibrations at different temperatures or, if some parameters of the LED's output spectrum are available, by a series of calculations to compensate for temperature drifts.
  • Equation (6.3) can then be used to describe the LED's optical output for all duty cycles D 1 at 100% and at reference temperature T re f, wherein the index RA indicates the coordinates of either a red, amber or lumped red and amber primary color and wherein L is the maximum lumen output of the lighting device at T re f.
  • Figure 7 shows schematically a complete controller arrangement for a lighting unit 10 with four LEDs 11 of the primary colors RAGB.
  • the temperature T of the heat sink of the device is measured with a temperature sensor 13 and communicated to a feed forward controller 20.
  • the feed forward controller 20 determines four control signals according to the described approach ( Figure 6), i.e. by combining two colors (R and A) to one virtual light emitter (RA) and by multiplying the target color point (X ⁇ ,Y ⁇ ,Z ⁇ ) with the inverse of the associated calibration matrix C(T) that is valid for the measured temperature T.
  • the color point (R,G,B) of the lighting unit 10 is measured by a color sensor 12 and communicated to a feedback controller 30, e.g. a PID controller.
  • the feedback controller 30 determines correction factors for the feed forward control signals (D R , D A , D G , D B )ff.
  • the LEDs 11 are finally driven with the resulting corrected control signals.
  • Figure 8 shows a variant of the system of Figure 7, wherein the lighting unit 10 comprises a flux sensor 12 and wherein the LEDs 11 are driven by pulse-width modulation (PWM).
  • PWM results in the LEDs having a constant forward current, but varying duty cycle or on-time, which essentially means they are switched on periodically and for a certain amount of time only.
  • This drive method has the advantage that the forward current no longer changes the emitted wavelength (as the current remains constant over time). And this means that the mixed color of the unit has less dependencies.
  • the LEDs In order to determine the output (power) of each LED color with the single sensor 12, the LEDs must be turned on sequentially in time to be able to discern each separate LED color (or alternatively frequency separation might be used). This means that the sensor 12 measures the instantaneous output. Through a number of measurements and some simple calculations, the output of each LED color can then be determined from the measured (single LED) ⁇ by a color signal extractor 31. However, measuring the instantaneous output and using PWM driven LEDs means that the measured signal does not change when the duty cycle is changed. As the PID setpoint represents the desired output of each LED at the (constant) forward current applied during a duty cycle, the setpoint does not depend on the chosen color point.
  • the temperature T of the heat sink is measured by the temperature sensor 13 and communicated to the PID controller 30. Based on the measured temperature T, the PID controller 30 can then change (in a feed forward way) its setpoint to match the peak wavelength shift of the LEDs due to changes in their temperature. Further, the system functions as described in Figure 7.
  • the approach to lump two (or more) LEDs is primarily used to determine the initial driving commands that can be used to obtain a desired color.
  • these initial commands are only valid at a certain temperature T (the temperature at which the calibration matrix C is determined). Therefore, if the LEDs are also operated at different temperatures (or when they have aged considerably), these feed forward commands alone do not yield the desired color accurately enough, and the feedback controller 30 is needed to achieve the needed accuracy.
  • the feedback algorithm can have a lot of different forms and may for example use the shown color sensor 12 or a simple, unfiltered sensor (cf. US 6 441 558 Bl). In all cases, the feedback algorithm can be constructed such that it works independently of the chosen color point (and thus of the initial driving commands).
  • the additional degree of freedom in a (e.g. RGBA) lighting device can be used to optimize light technical properties like CRI, lumen output, or power efficiency (lumen per used Watt of electrical power).
  • the graphs of Figure 9 show in this respect the significant difference in lumen output (left side) and color rendering index (right side) for driving ratios optimized on either maximum flux output (black lines) or maximum color rendering (gray lines). The results change when the heat sink temperature rises (top diagrams corresponding to room temperature 25°C, bottom diagrams to an elevated temperature of about 50 0 C).
  • the duty cycles for a four (or more) color LED system depending on the chosen target color point.
  • the power at which the lamp drives its LED colors should be optimized on the color rendering properties of the lamp output (CRI, Rg etc).
  • the power applied to each LED color or the total lumen output of the lamp can be optimized.
  • the driving ratios can be determined by interpolating between both algorithms.
  • Figure 11 presents an exemplary flow diagram of how to determine the content of such a LUT.
  • block 1 the required range of Correlated Color Temperatures (CCT) over the BBL is specified, while block 2 specifies the allowable visible difference between the discrete steps on the BBL.
  • Block 3 specifies the available amount of memory for storing the LUT.
  • discrete CCT values are determined based on the inputs of blocks 1 and 2, while in block 5 discrete CCT values are removed from this list to fit the table into the available memory. Between the remaining points, an interpolation has to be done.
  • the power levels D 1;Opt are generated in block 6 for each LED color for the remaining CCT values while optimizing on the chosen criterion (e.g. maximal CRI).
  • the parameters of the offline optimization algorithm can be tuned specifically to the application or to the lamp in question. For instance, it may not make much sense to increase the color rendering properties from excellent to perfect when the lumen output decreases significantly. A better solution may therefore be found by optimizing on a weighted combination of both color rendering properties and lumen output. Additional optimization parameters (e.g. lumen/Watt) may also be introduced. Depending on the number of available LED colors, even more restraints may be required.
  • the system is typically aware of the possible lumen output of each LED color at the current temperature and/or age.
  • BBL can also be found by interpolating between the closest BBL point and the lumen optimized calculation.
  • the applied algorithm finds the driving ratios for a certain color at reference temperature while also achieving maximum lumen output. By continuously substituting the available lumen output for each (lumped) LED color at the present junction temperature, the algorithm can be used to determine the driving ratios for maximum lumen output.
  • the technologies described above can particularly be applied to LED fixtures using more than three LED colors. They are especially suitable for general lighting or LCD backlighting, but may also be applied in other application areas where lumen output and color rendering is very important.
  • Figure 12 summarizes in principal drawings a) to c) the three control examples described above.
  • the drawings show lighting devices 100, 200, and 300 with
  • N 5 light emitters 11 (e.g. LEDs) of different primary colors R, A, G, B, C that shall be controlled in such a way that a number k of target values (e.g. color point and/or brightness) are optimally matched, wherein k is typically smaller than N.
  • the control problem is solved by applying at least two different control schemes simultaneously to different light emitters or during different operating conditions to all light emitters.
  • one group Gi of light emitters is controlled by a feed forward controller Cff, while the group G2 of residual light emitters is controlled by a feedback controller Ca that receives measuring inputs from a color sensor 12.
  • the driving commands issued by a controller CO to light emitters of the groups Gi, G 2 are coupled, thus lumping these light emitters to a virtual light emitter for the purpose of control.
  • the only light emitter of group G3 is controlled individually.
  • the controller CO is preferably combined with a feedback controller for adjusting the control signals in view of temperature drifts, aging etc.
  • control schemes Cl and C2 are pursued by control schemes Cl and C2, respectively, under different operating conditions OpI and Op2.
  • This may for example comprise the optimization of color rendering index on the black-body line and the optimization of lumen output elsewhere.
  • a lighting device (100, 200, 300), comprising a) a number N of light emitters (11) with different primary colors; b) a controller (20, 30, C ff , Ca, CO, Cl , C2) for selectively driving the light emitters such that k target values are optimally matched by the common light output of the light emitters, wherein at least two different control schemes are applied by the controller.

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  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

L'invention porte sur un dispositif d'éclairage (100, 200, 300) avec N émetteurs de lumière (11) (par exemple, DEL) de différentes couleurs primaires (par exemple, R, A, G, B, C) qui devraient en être commandés de telle sorte qu'un nombre k de valeurs cibles (par exemple, point de couleur et/ou brillance) sont mis en correspondance de façon optimale, ou k est typiquement inférieur à N. Le problème de commande est résolu par l'application d'au moins deux schémas de commande différents simultanément à différents émetteurs de lumière ou pendant différentes conditions de fonctionnement à tous les émetteurs de lumière. Dans un premier mode de réalisation particulier (100), certains des émetteurs de lumière (G1) peuvent être commandés par un contrôleur à action directe (Cff), tandis que le reste (G2) est commandé par un contrôleur à rétroaction (Cfb). Dans un autre mode de réalisation (200), les instructions de commande de certains des émetteurs de lumière (G1, G2) peuvent être couplées, rassemblant ainsi ces émetteurs de lumière en un émetteur de lumière virtuel à des fins de commande. Dans encore un autre mode de réalisation (300), différents critères d'optimisation (C1, C2) sont poursuivis sous différentes conditions opérationnelles (Op1, Op2), par exemple l'optimisation de l'indice de rendu de couleur sur la ligne de corps noir et l'optimisation d'un flux lumineux ailleurs.
PCT/IB2008/051753 2007-05-10 2008-05-06 Dispositif d'éclairage avec une pluralité d'émetteurs de lumière WO2008139369A1 (fr)

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WO2011143197A3 (fr) * 2010-05-13 2012-03-29 Cree, Inc. Dispositif d'éclairage et procédé de fabrication
WO2013052403A1 (fr) * 2011-10-02 2013-04-11 Cree, Inc. Décalage de compensation de courbe de température
US8890420B2 (en) 2011-10-02 2014-11-18 Cree, Inc. Temperature curve compensation offset
EP2897018A1 (fr) * 2014-01-20 2015-07-22 Irsap Spa Procédé pour fournir une indication visuelle de la température ambiante sur un thermostat électronique et ledit thermostat
US9253855B2 (en) 2012-05-29 2016-02-02 Koninklijke Philips N.V. Tunable lighting system
US9907146B2 (en) 2014-08-11 2018-02-27 Philips Lighting Holding B.V. Light system interface and method
WO2018160743A1 (fr) 2017-02-28 2018-09-07 Quarkstar Llc Stabilisation de couleur sur la durée de vie de sources de lumière artificielle à décalage de couleur
NL2023938B1 (en) * 2019-10-02 2021-05-31 Eldolab Holding Bv Method of multi-mode color control by an LED driver
WO2022207720A1 (fr) * 2021-03-31 2022-10-06 Eldolab Holding B.V. Procédé de commande de couleur multimode par un pilote de del

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CN114128403A (zh) * 2019-05-17 2022-03-01 亮锐有限责任公司 用于led颜色调节的用户控制模态

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WO2002047438A2 (fr) * 2000-12-07 2002-06-13 Koninklijke Philips Electronics N.V. Led luminary system
WO2006129260A2 (fr) * 2005-06-03 2006-12-07 Koninklijke Philips Electronics N.V. Systeme et procede de commande d'une balise a diodes electroluminescentes
WO2007060570A1 (fr) * 2005-11-22 2007-05-31 Koninklijke Philips Electronics N.V. Systeme d’eclairage par led et son procede de commande

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CN102428755A (zh) * 2009-05-19 2012-04-25 欧司朗股份有限公司 用于调整色度坐标的方法和装置
WO2010133481A1 (fr) * 2009-05-19 2010-11-25 Osram Gesellschaft mit beschränkter Haftung Procédé et dispositif de réglage d'un point de couleur
US8604702B2 (en) 2009-05-19 2013-12-10 Osram Gmbh Method and apparatus for setting a chromaticity coordinate
CN102428755B (zh) * 2009-05-19 2015-05-27 欧司朗股份有限公司 用于调整色度坐标的方法和装置
US8896197B2 (en) 2010-05-13 2014-11-25 Cree, Inc. Lighting device and method of making
WO2011143197A3 (fr) * 2010-05-13 2012-03-29 Cree, Inc. Dispositif d'éclairage et procédé de fabrication
US9137873B2 (en) 2011-10-02 2015-09-15 Cree, Inc. Overcurrent handling for a lighting device
US10021756B2 (en) 2011-10-02 2018-07-10 Cree, Inc. Over-temperature handling for lighting device
CN103947291A (zh) * 2011-10-02 2014-07-23 科锐 温度曲线补偿偏移
WO2013052403A1 (fr) * 2011-10-02 2013-04-11 Cree, Inc. Décalage de compensation de courbe de température
US9713226B2 (en) 2011-10-02 2017-07-18 Cree, Inc. Over-voltage handling of lighting device
US8890420B2 (en) 2011-10-02 2014-11-18 Cree, Inc. Temperature curve compensation offset
US9253855B2 (en) 2012-05-29 2016-02-02 Koninklijke Philips N.V. Tunable lighting system
EP2897018A1 (fr) * 2014-01-20 2015-07-22 Irsap Spa Procédé pour fournir une indication visuelle de la température ambiante sur un thermostat électronique et ledit thermostat
US9907146B2 (en) 2014-08-11 2018-02-27 Philips Lighting Holding B.V. Light system interface and method
WO2018160743A1 (fr) 2017-02-28 2018-09-07 Quarkstar Llc Stabilisation de couleur sur la durée de vie de sources de lumière artificielle à décalage de couleur
NL2023938B1 (en) * 2019-10-02 2021-05-31 Eldolab Holding Bv Method of multi-mode color control by an LED driver
US11140759B2 (en) 2019-10-02 2021-10-05 Eldolab Holding B.V. Method of multi-mode color control by an LED driver
WO2022207720A1 (fr) * 2021-03-31 2022-10-06 Eldolab Holding B.V. Procédé de commande de couleur multimode par un pilote de del
NL2027881B1 (en) * 2021-03-31 2022-10-17 Eldolab Holding Bv Method of multi-mode color control by an LED driver

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