EP3032918B1 - Method for operating an assembly for emitting light with adjustable intensity and/or colour location - Google Patents

Description

The invention relates to a method for operating an arrangement designed to emit light whose brightness and/or color location can be adjusted and which has at least two electrically controllable LED light sources which differ from one another in a dominant wavelength of the light they generate in each case, wherein the light emitted by the arrangement is generated by additively mixing the light generated by the individual LED light sources, the LED light sources being supplied individually in such a way that a predetermined dominant wavelength of the light emitted by the arrangement is independent of the respective brightness of this light is constant and/or that a predetermined brightness of the light emitted by the arrangement is constant independently of the respective dominant wavelength of this light.

The invention also relates to a system for generating light whose brightness and/or color location can be adjusted, having at least one arrangement for emitting light whose brightness can be adjusted and at least one electronic control unit configured to control the arrangement, the arrangement having at least two electrically has controllable LED light sources which differ from one another in a dominant wavelength of the light they generate in each case, the LED light sources being designed to be controllable and arranged in relation to one another in such a way that the light emitted by the arrangement is produced by additively mixing the light emitted by the individual LED Light sources each light generated is generated, the control unit being set up in such a way that the LED light sources are supplied individually in such a way that a predetermined dominant wavelength of the light emitted by the arrangement is independent of the respective brightness of this light s is constant and/or that a predetermined brightness of the light emitted by the arrangement is constant independently of the respective dominant wavelength of this light.

A dominant wavelength provides a way of describing a polychromatic mixture of light in terms of a monochromatic light that produces a similar hue perception to the polychromatic mixture of light. In the CIE standard color table from 1931, which is known to the person skilled in the art, a line which corresponds to that in the white point contained in the CIE chromaticity diagram and a point representing the color of a polychromatic light mixture produced by a light source can be extrapolated in such a way that the line intersects the edge of the CIE chromaticity diagram at two points of intersection. The point of intersection that is closer to the point for the color of the polychromatic light mixture represents the dominant wavelength of the color of this light mixture as a wavelength of a monochromatic light or a certain pure spectral color. The dominant wavelength depends on the entire course of the optical spectrum, which the light to be characterized with regard to the color locus has. A spectrum is often characterized by Parameters such as peak wavelength and FWHM are described. However, the color locus is only clearly defined by these parameters if further information about the spectrum is known, such as symmetry properties. For example, if an LED has a Gaussian curve, the spectrum and thus the dominant wavelength is clearly determined by specifying the peak wavelength and the half-width. However, this does not apply to any other, in particular asymmetrical, spectra. For this reason, in the present description, the color locus is described by the dominant wavelength and not by other spectral parameters.

Arrangements for emitting light whose brightness can be adjusted, which have at least two LED light sources, are known. In order to control the brightness of the light they emit, such arrangements are usually supplied with a pulsed electrical current, the pulse width of which is modulated in accordance with the desired brightness. It is thus continuously switched back and forth between a current intensity of zero and a constant current intensity, with the mean current intensity caused thereby determining the optical radiometric radiant power or the photometric radiant power and thus the brightness of the light emitted by the respective arrangements. This pulsed driving of corresponding arrays causes the light emitted by the arrays to be pulsed.

It is known that the dominant wavelength or the color locus in the CIE standard chromaticity diagram of a light generated by an LED light source is highly dependent on the amperage of the current with which the LED light source is supplied. Not only the peak wavelength can change, but also the shape and/or the width of the spectrum. In the above-described pulsed control of an arrangement, the amperage of the current supplying the LED light sources is constant during a pulse width, as a result of which the light generated by the LED light sources of the arrangement or the light emitted by the arrangement during a pulse width is essentially a constant dominant wavelength or has a constant color locus. However, a slight change in the dominant wavelength or the color locus of the light is caused in the above-described control of an arrangement by the fact that at a lower average current intensity of the current supplying the LED light sources of the arrangement, ie with a reduction in the pulse width compared to a Pulse pause, the electrical power loss is lower. This is possible during operation of an arrangement with less heating of the arrangement or the LED light sources of the arrangement and thus with an influence on the spectral behavior of the LED light sources, in particular with a shift in the dominant wavelength and possibly with a change in the shape of one LED light source generated light spectrum, along. It is known to correct this temperature effect by means of a corresponding characteristic curve or a corresponding family of characteristic curves, which is used to adjust the LED light source or LED light sources with pulsed current.

A method and a system with the features mentioned above are out WO 2008/137984 A1 , in which the light emitted by the arrangement is detected by a sensor and the power supply of the individual LED light sources is readjusted on the basis of the detected light. Other procedures and systems are out DE 10 2013 207961 A1 and Deurenberg P et al: "Achieving color point stability in RGB multi-chip LED modules using various control loops", Proceedings of SPIE, SPIE - International Society for optical engineering, US, Vol. 5941, 7 September 2005, pages 59410C-1 , XP002428542 , famous. Other procedures and systems are out WO 2007/148250 A1 , WO 2011/157604 A1 and WO 2012/077046 A2 famous.

A disadvantage of the conventional arrangements is that the pulsed light emitted by these arrangements is unsuitable if it leads to undesirable effects when used. This is the case in particular when such lighting is used for film recordings, since the frequency of the pulsed light with the image refresh rate can lead to beats. This effect could be eliminated by synchronizing the pulse frequency of a light emitted by the arrangement with the frame rate, ie the frame refresh rate with which the images of a film recording are generated. However, this would lead to an undesirably high level of technical complexity. In addition, with digital image processing, the different pulse widths of the different LED light sources can lead to disturbing image segments with the wrong color or black stripes in the image display. In addition, long-term exposure to pulsating light with frequencies < 1 kHz is perceived by the human eye as disturbing and questionable in terms of well-being.

The object of the invention is to make it possible to emit a light that can be adjusted in terms of its brightness and/or its color location with an arrangement of the type mentioned at the outset, in which the above-mentioned disadvantages do not occur.

This object is achieved by a method having the features of claim 1 or claim 2 and by a system having the features of claim 5 or claim 6. Advantageous designs are given in the subclaims and the description, which, taken individually or in various combinations with one another, can represent an aspect of the invention.

According to the invention, the LED light sources of the arrangement are supplied with a direct current, ie with an unpulsed current, so that the light emitted by the arrangement is not pulsed—as is conventional—but is continuous. This avoids the disadvantages described above with reference to the prior art. Controlling the brightness and/or the color locus of the light emitted by the arrangement is achieved by controlling the current strength of the direct current individually supplying the individual LED light sources.

According to the invention, the LED light sources are supplied with direct current in such a way that a predetermined dominant wavelength of the light emitted by the arrangement is constant regardless of the respective brightness of this light or - in the entire range in which the brightness of the light, i.e. the photometric radiant power (i.e the luminous flux measured in lumens) can be adjusted only varies by a predetermined maximum amount. This means that the set dominant wavelength or the color locus of the light emitted by the arrangement is always the same, regardless of the brightness set in each case. This can be achieved by individually supplying the individual LED light sources of the arrangement with direct current.

Additionally or alternatively, the LED light sources are individually supplied with direct current in such a way that a predetermined brightness of the light emitted by the arrangement is constant regardless of the respective dominant wavelength of this light or - in the entire range in which the brightness of the light, i.e. the photometric Radiant power (i.e. the luminous flux measured in lumens) can be adjusted, only varies by a predetermined maximum amount. This means that the set brightness of the light emitted by the arrangement is always the same, regardless of the respective, in particular changeable, dominant wavelength of this light. This can be achieved by individually supplying the individual LED light sources of the arrangement with direct current.

An arrangement operated according to the method according to the invention can also have three or more LED light sources. A plurality of LED light sources, in particular connected in series with one another, can also be present from each type of LED light source. The arrangement can be set up to emit colored, white and/or variable light in terms of its color locus.

The LED light sources of the arrangement can be supplied with a direct current by means of a driver circuit, the current intensity of which can be set via the driver circuit, but is kept constant at a desired value after the respective setting.

According to an advantageous embodiment, at least one LED light source is supplied with direct current, taking into account a predetermined dependence of the dominant wavelength of the light generated by this LED light source on a current intensity of a direct current supplying this LED light source. A characteristic can be used for this purpose, which reflects the dependency of the dominant wavelength of the light generated by the LED light source on the current intensity of the direct current supplying this LED light source. Such a characteristic curve can additionally contain a predetermined dependency of the dominant wavelength of the light generated by the LED light source on a temperature of this LED light source and/or on a temperature of the arrangement. It is also possible for two or more or all LED light sources to be operated, each taking into account a predetermined dependency of the dominant wavelength of the light generated by the respective LED light source on the current strength of the direct current supplying the respective LED light source be supplied with direct current. The predetermined dependency can contain coordinates of the CIE standard color table with regard to the dominant wavelength or the color locus of the light generated by the respective LED light source.

The individual drive currents for the individual LED light sources, which ensure that the color locus of the light emitted by the entire arrangement (within specified limits) is constant, can be determined in a variety of ways from the individual characteristic curves or characteristic curve fields for all individual LED light sources . For example, a multidimensional dependency of the luminous flux, which defines the brightness, of the light generated by the entire arrangement can be established from the associated individual drive currents for the individual LED light sources. A value for the luminous flux can then be specified with a manipulated variable (e.g. the resistance value of a potentiometer or a digital value of a control signal). The individual drive current for the individual LED light sources can then be determined immediately from the known dependency and selected or set accordingly. The multidimensional dependency can also include and take into account the temperature dependency of the dominant wavelengths of the individual LED light sources. The aging or degradation of the LED light sources can also be taken into account in this way.

The brightness control can also be effected in such a way that an LED light source, which can be referred to as a lead LED light source, is supplied with an arbitrary current. Since the dependency of the dominant wavelength of this guide LED light source is known, all other LED light sources can be controlled with a direct current selected in such a way, taking into account their dependencies of the respective dominant wavelength on the respective supply direct current, that the specified dominant wavelength of the entire arrangement emitted light remains constant or only fluctuates within a tolerated value range. Here, therefore, it is not the luminous flux of the light generated by the entire arrangement that can be specified, but rather the amperage of the drive current for the guide LED light source. Of course, this also depends on the luminous flux of the light generated by the guide LED light source, but usually not linearly over the entire desired adjustment range for the luminous flux of the guide LED light source. The LED light source becomes the leading LED light source use that makes the greatest contribution to the luminous flux of the light generated by the entire arrangement.

According to a further advantageous embodiment, a temperature of at least one LED light source is detected, this LED light source being supplied with direct current taking into account a predetermined dependency of the dominant wavelength of the light generated by this LED light source on the temperature of this LED light source. A separate characteristic can be used for this purpose, which reflects the dependency of the dominant wavelength of the light generated by the LED light source on the temperature of the respective LED light source. Such a characteristic curve can be used during operation of the arrangement to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the LED light source or to cancel it by appropriate control of the power supply of the LED light source. It is also possible for two or more, in particular all, LED light sources to be supplied, each taking into account a predetermined dependence of the dominant wavelength of the light generated by the respective LED light source on the temperature of the respective LED light source. The temperature of an LED light source can be detected using a temperature sensor. The predetermined dependency can contain coordinates of the CIE standard color table with regard to the dominant wavelength or the color locus of the light generated by the respective LED light source.

A further advantageous embodiment provides that at least one LED light source is supplied with direct current, taking into account a predetermined dependence of the dominant wavelength of the light emitted by the arrangement on a current intensity of a direct current supplying the arrangement as a whole. A characteristic can be used for this purpose, which reflects the dependency of the dominant wavelength of the light generated by the LED light source on the current intensity of the direct current supplying the arrangement as a whole. Such a characteristic curve can also have a predetermined dependence of the dominant wavelength of the light generated by the LED light source on a temperature of this LED light source and/or a temperature of the assembly. Two or more, in particular all, LED light sources can also be supplied with direct current, taking into account a predetermined dependency of the dominant wavelength of the light generated by the respective LED light source on the current strength of the direct current supplying the arrangement as a whole. The predetermined dependency can contain coordinates of the CIE standard color table with regard to the dominant wavelength or the color locus of the light generated by the respective LED light source.

Furthermore, it is considered advantageous if at least one LED light source is supplied with direct current, taking into account a predetermined dependency of the dominant wavelength of the light emitted by the arrangement on a temperature of the arrangement. A characteristic can be used for this purpose, which reflects the dependency of the dominant wavelength of the light generated by the LED light source on the temperature of the arrangement. Such a characteristic curve can be used during operation of the arrangement to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the LED light source or to cancel it by appropriate control of the power supply of the LED light source. It is also possible for two or more, in particular all, LED light sources to be supplied with direct current, each taking into account a predetermined dependency of the dominant wavelength of the light generated by the respective LED light source on the temperature of the arrangement. The predetermined dependency can contain coordinates of the CIE standard color table with regard to the dominant wavelength or the color locus of the light generated by the respective LED light source.

According to a further advantageous embodiment, at least one LED light source is supplied with direct current, taking into account the current intensity of a direct current supplying at least one further LED light source. Two or more LED light sources can also be supplied with direct current, each taking into account the current strength of a direct current supplying at least one further LED light source. For this purpose, a characteristic curve or a family of characteristic curves can be used which, for predetermined dominant wavelengths or color coordinates of the light emitted by the arrangement, shows the dependence of the current intensity of the current supplying the at least one LED light source on the current intensity of the at least one other LED light source powering direct current reproduces. As a result, when there is a change in the current supplying the at least one further LED light source, the current supplying the at least one LED light source can be tracked in order to keep the dominant wavelength or the color locus of the light emitted by the arrangement constant. The tracking can take place continuously or discretely at intervals of about 10 ms to about 100 ms, with characteristic curves or characteristic curve fields arranged sufficiently close to one another, which differ from one another only by small differences in the current intensity of the direct current supplying the at least one further LED light source , the respective next characteristic or the respective next family of characteristics can be selected for determining the current intensity of the direct current supplying the at least one LED light source. Instead, a linear interpolation between values from two characteristic curves or characteristic curve fields arranged adjacent to one another or a non-linear interpolation from values for more than two characteristic curves or characteristic curve fields arranged adjacent to one another can also be undertaken. Such a characteristic or such a family of characteristics can additionally contain a predetermined dependence of the dominant wavelength of the light generated by the LED light source on a temperature of this LED light source and/or on a temperature of the arrangement.

According to a further advantageous embodiment, the LED light sources are supplied with direct current in such a way that the color locus of the light emitted by the arrangement is on or near the Planck curve in at least one predetermined sub-range of a color temperature range of 1500 K to 10000 K. The size of the partial range is preferably at least 1000 K, preferably at least 2000 K or particularly preferably at least 3000 K. The partial range preferably extends from 3500 K to 4500 K, preferably from 3500 K to 5500 K or particularly preferably from 2700 K to 6500 K. The Planckian curve is contained in the 1931 CIE chromaticity chart, which is known to those skilled in the art. The shape of the Planckian curve is defined by the colors of the radiation from a blackbody at different temperatures.

Advantageously, the LED light sources are supplied with direct current in such a way that the color locus of the light emitted in each case by the arrangement is within a MacAdam ellipse associated with a reference hue lying on Planck's curve the preferred value is 10, 6, 4, 3 or less. These values are a measure of the size of the MacAdam ellipse. The mathematical relationship for the MacAdam ellipse is 12.5*X ² + 17.5*X*Y + 33.25*Y ² + 6.25 - 12.5*X - 27.5*Y = 0 and X + Y + Z = 1, where X, Y and Z represent the tristimulus values. The color locus can thus lie within a MacAdam ellipse with the value 10, 6, 4, 3 or smaller on or near the Planckian curve. This high level of accuracy with regard to the desired optimal position of the color point of the light emitted by the arrangement makes it possible to keep the color point of the light emitted by the arrangement as close as possible or on the Planckian curve.

The advantages and embodiments mentioned above in relation to the method are correspondingly associated with the system according to the invention. The electronic control unit can include at least one microprocessor. The control of the arrangement that can be achieved with the electronic control unit can optimally adapt the arrangement to the respective application. In particular, the LED light sources can be controlled by means of the electronic control unit with regard to the electrical power consumed or the optical radiometric power emitted or the photometric power emitted by them in such a way that the desired color locus results.

The electronic control unit can include a driver circuit which controls the LED light sources, each with a predetermined electrical power, in order to generate light with an overall spectrum which has the desired color temperature and has the desired color locus, in particular on or near the Planckian curve. For this purpose, each individual LED light source can be connected to an associated output of the driver circuit. However, one output of the driver circuit can also be provided for each light source, it being possible for the individual LED light sources to be connected in series and/or in parallel to the output of the driver circuit.

According to an advantageous embodiment, the LED light sources of the arrangement at least one LED light source set up to generate blue light, in particular with a dominant wavelength between 380 nm and 480 nm, which has at least one light-emitting diode, at least one LED light source set up to generate conversion light with a color lying in a conversion range, which has at least one light-emitting diode set up for generating blue light and at least one conversion unit set up for photoluminescence, and/or at least one for generating red light, in particular with a dominant wavelength between 600 nm and 640 nm, or green light, in particular with a dominant wavelength between 500 nm nm and 560 nm furnished LED light source, which has at least one light-emitting diode.

Depending on the intended use, the arrangement can also have two or more LED light sources of each type of LED light source, for example connected in series with one another. Within the scope of the invention, the arrangement can also have two or more blue light-emitting diodes, conversion light sources and/or red light sources and different combinations of these components in order to be able to optimally adapt the arrangement to different applications, in particular with regard to the intensity of the light it can emit. The LED light sources can be controlled by the electronic control unit in terms of the electrical power they consume or the optical radiometric power they deliver or the photometric power they deliver in such a way that a desired color locus results, in particular on or near the Planckian curve . This controllability of the arrangement or its components allows, for example, a very precise simulation of real daylight in a room, for example an office, by simulating the course of the color temperature of daylight (yellowish in the morning and evening and more bluish at noon). However, the arrangement can also be driven to generate white light with a constant color temperature.

The LED light source set up to generate conversion light can have one, two or more light-emitting diodes set up to generate blue light, part of the light of which is emitted by the arrangement and part of which is used to excite the conversion unit set up for photoluminescence. The dominant wavelength of the blue light generated by a light-emitting diode of the LED light source set up to generate conversion light can be smaller than the dominant wavelength of the conversion light generated by photoluminescence from the conversion unit excited with this blue light.

The LED light source configured to generate red light can also have at least one conversion unit and at least one light-emitting diode, the light-emitting diode being arranged relative to the conversion unit in such a way that at least part of the light generated by the light-emitting diode impinges on the conversion unit. Accordingly, instead of a red light-emitting diode emitting red light, a light-emitting diode, in particular generating blue light, and a suitable conversion unit are used to form the LED light source set up to generate red light. Alternatively, a red light-emitting diode configured to generate red light can be used to form the LED light source configured to generate red light.

According to a further advantageous embodiment, the system has at least one temperature sensor with which the temperature of at least one LED light source can be detected, in particular directly or indirectly. The temperature of two or more, in particular all, LED light sources or of the entire arrangement can also be detected with the temperature sensor. The temperature sensor is connected wirelessly or wired to the electronic control unit. Alternatively, the temperature of at least one LED light source can also be determined indirectly from the light generated by the LED light source, for example from the peak wavelength or half-width of the spectrum generated. Furthermore, the temperature of at least one LED light source can be determined from the electrical properties, such as voltage drop or capacitance.

According to a further embodiment of the system according to the invention, information is stored in at least one non-volatile electronic memory which is used to determine the current strengths of the individual supply currents for at least one of the at least two of the LED light sources.

• eine Abhängigkeit der dominanten Wellenlänge des von wenigstens einer LED-Lichtquelle erzeugten Lichts von einer Stromstärke eines diese LED-Lichtquelle versorgenden Gleichstroms oder eine andere, diese Abhängigkeit beinhaltende Information und/oder,
• eine Abhängigkeit der dominanten Wellenlänge des von der Anordnung emittierten Lichts von einer Stromstärke eines die Anordnung versorgenden Gleichstroms oder eine andere, diese Abhängigkeit beinhaltende Information, und/oder
• eine Abhängigkeit einer Stromstärke eines wenigstens eine LED-Lichtquelle versorgenden Gleichstroms von der Stromstärke eines wenigstens eine weitere LED-Lichtquelle versorgenden Gleichstroms oder eine andere, diese Abhängigkeit beinhaltende Information.

Furthermore, it is considered advantageous if the system has at least one non-volatile electronic memory in which at least one is stored

• a dependency of the dominant wavelength of the light generated by at least one LED light source on a current intensity of a power supply of this LED light source direct current or any other information containing this dependency and/or,
• a dependency of the dominant wavelength of the light emitted by the arrangement on a current intensity of a direct current supplying the arrangement or other information containing this dependency, and/or
• a dependency of a current intensity of a direct current supplying at least one LED light source on the current intensity of a direct current supplying at least one further LED light source, or other information containing this dependency.

The advantages and embodiments mentioned above in relation to the method are correspondingly associated with this configuration.

• eine Abhängigkeit der dominanten Wellenlänge des von wenigstens einer LED-Lichtquelle erzeugten Lichts von der Temperatur, insbesondere von der Temperatur einer Sperrschicht dieser LED-Lichtquelle oder eine andere, diese Abhängigkeit beinhaltende Information, und/oder
• eine Abhängigkeit der dominanten Wellenlänge des von der Anordnung emittierten Lichts von einer Temperatur der Anordnung oder eine andere, diese Abhängigkeit beinhaltende Information.

It is also proposed that the non-volatile electronic memory be stored

• a dependency of the dominant wavelength of the light generated by at least one LED light source on the temperature, in particular on the temperature of a barrier layer of this LED light source or other information containing this dependency, and/or
• a dependency of the dominant wavelength of the light emitted by the arrangement on a temperature of the arrangement or other information containing this dependency.

This dependency or dependencies can be taken into account via separate characteristic curves for controlling the power supply of the LED light source. Alternatively, the dependency or the dependencies can be contained in a characteristic curve which reproduces at least one of the dependencies of the advantageous embodiment mentioned immediately above.

Fig. 1:

eine schematische Darstellung eines Ausführungsbeispiels für ein erfindungsgemäßes System;

Fig. 2:

ein Diagramm, das die CIE-Normfarbtafel und Farborte von LED-Lichtquellen eines Ausführungsbeispiels für ein erfindungsgemäßes System enthält;

Fig. 3:

einen Ausschnitt des in Figur 2 gezeigten Diagramms, der die Abhängigkeit eines Farbortes des von einer LED-Lichtquelle erzeugten Lichts von der Stromstärke des diese LED-Lichtquelle versorgenden Gleichstroms zeigt;

Fig. 4:

einen weiteren Ausschnitt des in Figur 2 gezeigten Diagramms, der die Abhängigkeit eines weiteren Farbortes des von einer weiteren LED-Lichtquelle erzeugten Lichts von der Stromstärke des diese LED-Lichtquelle versorgenden Gleichstroms zeigt;

Fig. 5:

ein Diagramm, das die CIE-Normfarbtafel und Farborte von LED-Lichtquellen eines Ausführungsbeispiels für ein erfindungsgemäßes System bei verschiedenen Temperaturen der LED-Lichtquellen enthält;

Fig. 6:

einen Ausschnitt des in Figur 5 gezeigten Diagramms, der die Abhängigkeit eines Farbortes des von einer LED-Lichtquelle erzeugten Lichts von der Temperatur dieser LED-Lichtquelle zeigt;

Fig. 7:

einen weiteren Ausschnitt des in Figur 5 gezeigten Diagramms, der die Abhängigkeit eines weiteren Farbortes des von einer weiteren LED-Lichtquelle erzeugten Lichts von der Temperatur dieser LED-Lichtquelle zeigt.

In the following, the invention is explained by way of example with reference to the enclosed figures using preferred exemplary embodiments, with the features presented below being able to represent an aspect of the invention both individually and in various combinations with one another. Show it

Figure 1:

a schematic representation of an embodiment of a system according to the invention;

Figure 2:

a diagram containing the CIE standard color chart and color locations of LED light sources of an embodiment of a system according to the invention;

Figure 3:

a section of the in figure 2 diagram shown, which shows the dependency of a color locus of the light generated by an LED light source on the amperage of the direct current supplying this LED light source;

Figure 4:

another section of the in figure 2 diagram shown, which shows the dependency of a further color locus of the light generated by a further LED light source on the amperage of the direct current supplying this LED light source;

Figure 5:

a diagram containing the CIE standard color table and color locations of LED light sources of an exemplary embodiment for a system according to the invention at different temperatures of the LED light sources;

Figure 6:

a section of the in figure 5 diagram shown, which shows the dependency of a color locus of the light generated by an LED light source on the temperature of this LED light source;

Figure 7:

another section of the in figure 5 diagram shown, which shows the dependency of a further color locus of the light generated by a further LED light source on the temperature of this LED light source.

figure 1 shows a schematic representation of an exemplary embodiment of a system 1 according to the invention for generating light whose brightness and/or color location can be adjusted. The system 1 comprises an arrangement 2 for emitting light whose brightness can be adjusted and an electronic control unit 3 which is set up for controlling the arrangement 2.

The arrangement 2 comprises three electrically controllable LED light sources 4, 5 and 6, which are in the dominant wavelength of the light generated by them differ from one another, with the LED light sources 4, 5 and 6 being designed to be controllable and arranged relative to one another such that the light emitted by the arrangement 2 is generated by additive mixing of the light generated by the individual LED light sources 4, 5 and 6 in each case.

The LED light sources 4, 5 and 6 of the arrangement 2 comprise an LED light source 4 set up to generate blue light, which has at least one light-emitting diode (not shown), an LED light source 5 set up to generate conversion light with a color lying in a conversion range , which has at least one light-emitting diode, not shown, set up to generate blue light and at least one conversion unit, not shown, set up for photoluminescence, and an LED light source 6 set up to generate red light, which has at least one light-emitting diode, not shown.

The system 1 also includes one or more temperature sensors 7 with which the temperature of the individual LED light sources 4 , 5 and 6 or the arrangement 2 can be detected and which emits temperature signals to the electronic control unit 3 . If several temperature sensors 7 are provided, one temperature sensor 7 can be assigned to a specific LED light source 4, 5 or 6 or to a light-emitting diode of the light source 4, 5 or 6 in question. It is of course also possible to assign one of several temperature sensors 7 to several selected LED light sources 4, 5 or 6. The temperature sensor or sensors 7 can be designed in any way, both as independent components and as sensors designed at least partially integrated with other components. For example, the forward voltage or the specific emission behavior of the LED light sources 4, 5 and 6 or one or more of the relevant light-emitting diodes can also be used to determine the temperature.

• eine Abhängigkeit der dominanten Wellenlänge des von wenigstens einer LED-Lichtquelle 4, 5 oder 6 erzeugten Lichts von einer Stromstärke eines diese LED-Lichtquelle 4, 5 bzw. 6 versorgenden Gleichstroms,
• eine Abhängigkeit der dominanten Wellenlänge des von der Anordnung 2 emittierten Lichts von einer Stromstärke eines die Anordnung 2 insgesamt versorgenden Gleichstroms, und/oder
• eine Abhängigkeit einer Stromstärke eines wenigstens eine LED-Lichtquelle 4, 5 oder 6 versorgenden Gleichstroms von der Stromstärke eines wenigstens eine weitere LED-Lichtquelle 4, 5 oder 6 versorgenden Gleichstroms.

The system 1 also has a non-volatile electronic memory 8 in which at least one is stored

• a dependency of the dominant wavelength of the light generated by at least one LED light source 4, 5 or 6 on a current intensity of a direct current supplying this LED light source 4, 5 or 6,
• a dependence of the dominant wavelength of the light emitted by the arrangement 2 on a current intensity of a direct current supplying the arrangement 2 as a whole, and/or
• a dependency of a current intensity of a direct current supplying at least one LED light source 4, 5 or 6 on the current intensity of a direct current supplying at least one further LED light source 4, 5 or 6.

The non-volatile electronic memory 8 can be in the form of an EPROM or EEPROM and is connected to the electronic control unit 3 in terms of communication.

In the non-volatile electronic memory, a dependence of the dominant wavelength of the light generated by at least one LED light source 4, 5 or 6 on the temperature of this LED light source 4, 5 or 6 and/or a dependence of the dominant wavelength of the Arrangement 2 emitted light be stored by a temperature of the arrangement 2.

The electronic control unit 3 is set up to supply the LED light sources 4, 5 and 6 individually with direct current in such a way that a dominant wavelength of the light emitted by the arrangement 2 is constant regardless of the respective brightness of this light. For this purpose, the arrangement 2, in particular its conductor tracks, is connected to the control unit 3 and the control unit 3 is designed in such a way that each of the LED light sources 4, 5 and 6 can be controlled or is controlled with such an electrical power that the respective LED -Light source 4, 5 or 6 emits such a spectrum that the additively mixed overall spectrum represents light with the desired properties.

The electronic control unit 3 can also be set up to supply the LED light sources 4, 5 and 6 individually with direct current in such a way that the brightness of the light emitted by the arrangement 2 is constant regardless of the changeable, dominant wavelength of this light.

For this purpose, the control unit 3 has an electronic controller 9 and three driver circuits 10, 11 and 12 connected to the electronic controller for communication purposes, with one driver output being connected to one of the LED light sources 4, 5 or 6 in each case. The driver circuits 10, 11 and 12 can be controlled in such a way that the LED light sources 4, 5 and 6 are operated individually with a predetermined constant direct current, so that the spectra generated by the LED light sources 4, 5 and 6 have the desired properties, in particular the radiometric or photometric output set by the brightness setting according to the invention. The electronic controller 9 can include at least one microcontroller.

The electronic controller 9 is connected in terms of communication to an input interface 18, via which default values for a desired color locus or for a dominant wavelength of the light emitted by the arrangement 2 and/or a desired brightness of the light emitted by the arrangement 2 can be generated, which can be wirelessly generated or can be transmitted to the electronic control by cable. The input interface 18 can include, for example, a potentiometer, a wirelessly coupled mobile unit, for example a mobile radio terminal, in particular a smartphone, or the like. When using a potentiometer to set the desired color locus or the brightness of the light emitted by the arrangement 2, the input interface 18 can also include a unit for generating digital values corresponding to the default values, which can be processed by the electronic controller 9 or its microcontroller . When using a smartphone, which can generate digital values corresponding to the default values and transmit them directly to the electronic control 9 or its microcontroller, a receiving unit can be present for the electronic control 9 in order to be able to receive the digital values generated by the smartphone.

figure 2 FIG. 12 shows a diagram which contains the CIE standard color table 1931 identified by the reference number 13. FIG. The diagram also shows a color locus 14 of the light generated by an LED light source 4 set up to generate blue light, a color locus 15 of the light generated by an LED light source 6 set up to generate red light, and a color locus 16 of the light generated by a LED light source 5, which is set up to generate conversion light with a color lying in a conversion range, generates light, the color locus 16 lying in a green-yellow color range. Planck's curve 17 is also drawn in the diagram. The color locations 14, 15 and 16 are connected to one another via lines to form a triangle, with the triangle all having a corresponding arrangement 2 possible adjustable color coordinates of the light emitted by the arrangement 2 are defined.

figure 3 shows a section of the in figure 2 diagram shown in the area of the color locus 14, which shows the dependence of the color locus 14 of the light generated by the LED light source 4 set up to generate blue light on the current intensity of the direct current supplying this LED light source 4. A color locus 14 is drawn in for each set current intensity, the color locus 14 with the greatest y-value being associated with a current of 1 mA and the color locus 14 with the smallest y-value being associated with a current of 200 mA. The color locations 14 were each determined shortly after the current was switched on by the LED light source 4 in order to rule out temperature effects when the LED light source 4 is operated with direct current.

figure 4 shows a section of the in figure 2 diagram shown in the area of the color locus 15, which shows the dependence of the color locus 15 of the light generated by the LED light source 6 set up to generate red light on the current strength of the direct current supplying this LED light source 6. A color locus 15 is drawn in for each set current intensity, the color locus 15 with the greatest y-value being associated with a current of 1 mA and the color locus 15 with the smallest y-value being associated with a current of 40 mA. The color locations 15 were each determined shortly after the current was switched on by the LED light source 6 in order to rule out temperature effects when the LED light source 6 was operated with direct current.

figure 5 shows a diagram of the CIE standard color table 13 and color locations 14, 15 and 16 of LED light sources 4, 5 and 6 of an exemplary embodiment of a system 1 according to the invention at different temperatures of the LED light sources 4, 5 and 6 in a range of approx -40°C to about 120°C. This is more accurate figures 6 and 7 refer to.

figure 6 shows a section of the in figure 5 diagram shown in the area of the color locus 14, which shows the dependence of the color locus 14 of the light generated by the LED light source 4 set up to generate blue light on the temperature of this LED light source 4. It is a color locus for different temperatures 14 are drawn in, the color location 14 with the largest y-value being associated with the temperature 120°C and the color location 14 with the smallest y-value being associated with the temperature -40°C. In the figure 6 The measured values shown were recorded with current pulses with a duration of 500 ns and a repetition rate of 500 μs in order to be able to rule out any influence of the heating of the barrier layer of the LED light source 4 .

figure 7 shows another section of the in figure 5 shown diagram in the area of the color point 15, which shows the dependence of the color point 15 of the light generated by the LED light source 6 set up to generate red light on the temperature of this LED light source 6. A color locus 15 is drawn in for different temperatures, the color locus 15 with the largest y-value being associated with the temperature -40°C and the color locus 15 with the smallest y-value being associated with the temperature 120°C. In the figure 7 The measured values shown were recorded with current pulses with a duration of 500 ns and a repetition rate of 500 μs in order to be able to rule out any influence of the heating of the barrier layer of the LED light source 6 .

The in the Figures 2 to 7 dependencies shown of the LED light sources 4, 5 and 6 or of the light generated by the LED light sources 4, 5 and 6 in each case on the temperature of the LED light sources 4, 5 and 6 and the current intensity of the respective LED light sources 4, 5 and 6 supplying direct current is taken into account via corresponding dependencies containing characteristic curves or characteristic curves in the individual supply of the LED light sources 4, 5 and 6 with direct current in order to be able to adjust the brightness of a light emitted by a corresponding arrangement 2 without changing the color locus of this to change additively mixed light.

An exemplary embodiment of the method according to the invention is described below, in which the supply of n LED light sources 1 to n with the individual direct currents I ₁ to I _n is controlled in a special way. For this control, one or more characteristic curves or characteristic diagrams are necessary, in which on the one hand the dependence of the color locus or the dominant wavelength λ _d of the light emitted by the arrangement 2 on the individual direct currents I ₁ to I _n through the individual LED light sources 1 to n is taken into account, without the influence of the respective temperature of the individual LED light sources 1 to n, which, as described, is determined by switching on the direct currents I ₁ to I _n through the LED light sources 1 to n only briefly and thereby detecting the dominant wavelength. The dependence of the color locus of the light emitted by the arrangement 2 from the individual direct currents I ₁ to I _n through the individual LED light sources 1 to n is deliberately switched off in the conventional pulse width modulated control of LED light sources. On the other hand, the at least one characteristic curve or the at least one characteristic field takes into account the additional dependency of the color locus of the light emitted by the arrangement 2 on the temperatures T of the individual LED light sources 1 to n or the temperatures of the junction layers of the individual LED light sources 1 to n.

A characteristic field can thus be used in which all possible n-tuples for the variables I ₁ to I _n , λ _d , Q (brightness of the light emitted by the arrangement 2), T are contained within value ranges for the individual variables. Theoretically, the luminous flux PHI, measured in lumens, can also be used for the brightness Q. However, in practice one tends to use a normalized brightness, for example between zero (or a lower limit, e.g. 10% of the maximum achievable brightness) and 100% of the maximum achievable brightness (this can also depend on the color point). In the characteristics map, only the currents I ₁ to I _n are real independent parameters (within specified value ranges). The parameters λ _d and Q depend on the independent parameters I ₁ to I _n and result from the independent parameters. The parameter T is also not completely independent of the independent parameters I ₁ to I _n . The independent parameters I ₁ to I _n influence the junction temperature of the respective LED light source 1 to n. However, the respective junction temperature also depends on the respective ambient temperature and the respective heat transfer resistance, which is decisive for the release of heat from the respective junction to the environment is.

In a first step, starting values for currents I0 ₁ to I0n can be determined as a function of specified values for the color locus or λ _d and the desired brightness Q (eg 80% of the maximum brightness). These starting values can be taken from the large characteristic diagram for a normal temperature T, for example. Instead, a separate characteristic map can be used for this, which links the values for I0 ₁ to I0 _n , λ _d and Q for a specific temperature T (eg room temperature).

In a second step, the influence of temperature can then be taken into account, where a temperature sensor 7 supplies a temperature value which initially deviates from an initial temperature. New values for the direct currents I ₁ to I _n for the new temperature value can then be taken from the characteristics map, or from a separate characteristics map, and the LED light sources 1 to n can be controlled accordingly.

The second step can also be divided into two sub-steps, with only the temperature influence on the direct currents I ₁ to I _n being corrected in a first sub-step in order to retain λ _d . A characteristic map used for this purpose can only take into account the temperature dependency, without taking into account the influence of the changed direct currents I ₁ to I _n on the color locus of the light emitted by the arrangement 2 . Such a characteristic field can be sufficient for the control/regulation of LED light sources 1 to n driven in a pulsed manner since there is no dependence of the color locus of the light emitted by the arrangement 2 on the direct currents I ₁ to I _n of temperature effects. In a second sub-step, the changed direct currents I ₁ to I _n can then be corrected by means of a further characteristic diagram, in which the dependence of the color locus of the light emitted by the arrangement 2 on the direct currents I ₁ to I _n is taken into account, so that the desired Color point of the light emitted by the arrangement 2 is achieved or maintained. The changed direct currents I ₁ to I _n will then again have an influence on the temperature T, etc. In the manner described, a desired state of equilibrium can be achieved after three such iterative steps.

Reference list:

1

system

2

arrangement

3

control unit

4

LED light source

5

LED light source

6

LED light source

7

temperature sensor

8th

non-volatile electronic memory

9

electronic control

10

driver circuit

11

driver circuit

12

driver circuit

13

CIE standard color chart

14

color location

15

color location

16

color location

17

Planckian curve

18

input interface

Claims (7)

1. Method for operating an arrangement (2) designed to emit light that can be adjusted in brightness or colour coordinate, which has at least two electrically controllable LED light sources (4, 5, 6) that differ in a dominant wavelength of the light they generate, wherein the light emitted by the arrangement (2) is generated by additive mixing of the light generated by each LED light source (4, 5, 6), the LED light sources (4, 5, 6) being supplied individually in such a way that a predefined dominant wavelength of the light emitted by the arrangement (2) is constant regardless of the respective brightness of the light emitted by the arrangement (2), or that a predefined brightness of the light emitted by the arrangement (2) is constant regardless of the respective dominant wavelength of the light emitted by the arrangement (2),

   characterized in that

   the predefined dominant wavelength of the light emitted by the arrangement (2) or the predefined brightness of the light emitted by the arrangement (2) is set by a control system without a closed feedback loop, by

   the at least two LED light sources (4, 5, 6) each being supplied with an individual DC supply current, taking into account at least one characteristic curve or at least one characteristic curve family, wherein each at least one characteristic curve or each at least one characteristic curve family reproduces a predefined dependency of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on a current strength of an individual DC supply current supplying that LED light source (4, 5, 6),

   wherein in each case a temperature of the at least two LED light sources (4, 5, 6) or a temperature of the arrangement (2) is detected and the at least two LED light sources (4, 5, 6) are each supplied with the respective individual DC supply current, taking into account a predefined dependence of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on the temperature of that LED light source (4, 5, 6) or taking into account a predefined dependence of the dominant wavelength of the light emitted by the arrangement (2) on a temperature of the arrangement (2), for which purpose one of the at least one characteristic curves is used that reflects the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the respective LED light source (4, 5, 6) or the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the arrangement (2), wherein in each case during the operation of the arrangement (2) the one of the at least one characteristic curves is used to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the respective LED light source (4, 5, 6).
2. Method for operating an arrangement (2) designed to emit light that can be adjusted in brightness or colour coordinate, which has at least three electrically controllable LED light sources (4, 5, 6) that differ in a dominant wavelength of the light they generate, wherein the light emitted by the arrangement (2) is generated by additive mixing of the light generated by each LED light source (4, 5, 6), the LED light sources (4, 5, 6) being supplied individually in such a way that a predefined dominant wavelength of the light emitted by the arrangement (2) is constant regardless of the respective brightness of the light emitted by the arrangement (2), or that a predefined brightness of the light emitted by the arrangement (2) is constant regardless of the respective dominant wavelength of the light emitted by the arrangement (2),

   characterized in that

   the predefined dominant wavelength of the light emitted by the arrangement (2) or the predefined brightness of the light emitted by the arrangement (2) is set by a control system without a closed feedback loop, by the at least three LED light sources (4, 5, 6) each being supplied with an individual DC supply current, taking into account at least one characteristic curve or at least one characteristic curve family, wherein each at least one characteristic curve or each at least one characteristic curve family reproduces a predefined dependency of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on a current strength of an individual DC supply current supplying that LED light source (4, 5, 6),

   wherein in each case a temperature of the at least three LED light sources (4, 5, 6) or a temperature of the arrangement (2) is detected and the at least three LED light sources (4, 5, 6) are each supplied with the respective individual DC supply current, taking into account a predefined dependence of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on the temperature of that LED light source (4, 5, 6) or taking into account a predefined dependence of the dominant wavelength of the light emitted by the arrangement (2) on a temperature of the arrangement (2), for which purpose one of the at least one characteristic curves is used that reflects the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the respective LED light source (4, 5, 6) or the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the arrangement (2), wherein in each case during the operation of the arrangement (2) the one of the at least one characteristic curves is used to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the respective LED light source (4, 5, 6).
3. Method according to either of Claims 1 or 2, characterized in that the LED light sources (4, 5, 6) are each supplied with individual DC supply currents in such a way that the colour coordinate of the light emitted by the arrangement (2) lies on or near the Planck curve (17) in at least one predefined sub-range of a colour temperature range of 1,500 K to 10,000 K.
4. Method according to any one of Claims 1 to 3, characterized in that the LED light sources (4, 5, 6) are each supplied with individual DC supply current in such a way that the colour coordinate of the light emitted by the arrangement (2) lies within a MacAdam ellipse assigned to a reference colour tone on the Planck curve (17) with the preferred value of 10, 6, 4, 3 or less.
5. System (1) for generating light adjustable in its brightness or colour coordinate, having at least one arrangement (2) for emitting light that can be adjusted in brightness and at least one electronic control unit (3), configured to control the arrangement (2), wherein the arrangement (2) has at least two electrically controllable LED light sources (4, 5, 6) that differ in a dominant wavelength of the light they each generate, wherein the LED light sources (4, 5, 6) are designed to be controllable and arranged with respect to each other in such a way that the light emitted by the arrangement (2) is generated by additive mixing of the light generated by each individual LED light source (4, 5, 6), the control unit being configured in such a way that the LED light sources (4, 5, 6) are supplied individually in such a way that a predefined dominant wavelength of the light emitted by the arrangement (2) is constant regardless of the respective brightness of the light emitted by the arrangement (2), or that a predefined brightness of the light emitted by the arrangement (2) is constant regardless of the respective dominant wavelength of the light emitted by the arrangement (2),

   characterized in that

   the predefined dominant wavelength of the light emitted by the arrangement (2) or the predefined brightness of the light emitted by the arrangement (2) is set by a control system without a closed feedback loop, for which purpose

   at least one non-volatile electronic memory (8) is provided, which stores at least one characteristic curve or at least one characteristic curve family for each LED light source (4, 5, 6), wherein the at least one characteristic curve or the at least one characteristic curve family reproduces a predefined dependency of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on a current strength of an individual DC supply current supplying that LED light source (4, 5, 6), and

   that the electronic control unit (3) is configured in such a way that the at least two LED light sources (4, 5, 6) are individually supplied with an individual supply DC current, taking into account the at least one characteristic curve or the at least one characteristic curve family, wherein

   the system comprises at least one temperature sensor (7) which detects a respective temperature of the at least two LED light sources (4, 5, 6) or a temperature of the arrangement (2), the electronic control unit (3) being configured in such a way that the at least two LED light sources (4, 5, 6) are each supplied with an individual DC supply current, taking into account a predefined dependence of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on the temperature of that LED light source (4, 5, 6) or taking into account a predefined dependence of the dominant wavelength of the light emitted by the arrangement (2) on a temperature of the arrangement (2), for which purpose the non-volatile electronic memory (8) stores one of the at least one characteristic curves which reflects the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the respective LED light source (4, 5, 6) or the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the arrangement (2), wherein in each case during the operation of the arrangement (2) the one of the at least one characteristic curves is used to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the respective LED light source (4, 5, 6).
6. System (1) for generating light adjustable in its brightness and colour coordinate, having at least one arrangement (2) for emitting light that can be adjusted in brightness and at least one electronic control unit (3), configured to control the arrangement (2), wherein the arrangement (2) has at least three electrically controllable LED light sources (4, 5, 6) that differ in a dominant wavelength of the light they generate, wherein the LED light sources (4, 5, 6) are designed to be controllable and are arranged with respect to each other in such a way that the light emitted by the arrangement (2) is generated by additive mixing of the light generated by each individual LED light source (4, 5, 6), the control unit being configured in such a way that the LED light sources (4, 5, 6) are supplied individually in such a way that a predefined dominant wavelength of the light emitted by the arrangement (2) is constant regardless of the respective brightness of the light emitted by the arrangement (2), or that a predefined brightness of the light emitted by the arrangement (2) is constant regardless of the respective dominant wavelength of the light emitted by the arrangement (2),

   characterized in that

   the predefined dominant wavelength of the light emitted by the arrangement (2) or the predefined brightness of the light emitted by the arrangement (2) is set by a control system without a closed feedback loop, for which purpose

   at least one non-volatile electronic memory (8) is provided, which stores at least one characteristic curve or at least one characteristic curve family for each LED light source (4, 5, 6), wherein the at least one characteristic curve or the at least one characteristic curve family reproduces a predefined dependency of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on a current strength of an individual DC supply current supplying that LED light source (4, 5, 6), and

   that the electronic control unit (3) is configured in such a way that the at least three LED light sources (4, 5, 6) are individually supplied with an individual supply DC current, taking into account the at least one characteristic curve or the at least one characteristic curve family, wherein

   the system comprises at least one temperature sensor (7) which can detect a respective temperature of the at least two LED light sources (4, 5, 6) or a temperature of the arrangement (2), the electronic control unit (3) being configured in such a way that the at least three LED light sources (4, 5, 6) are each supplied with an individual DC supply current, taking into account a predefined dependence of the dominant wavelength of the light generated by the respective LED light source (4, 5, 6) on the temperature of that LED light source (4, 5, 6) or taking into account a predefined dependence of the dominant wavelength of the light emitted by the arrangement (2) on a temperature of the arrangement (2), for which purpose the non-volatile electronic memory (8) stores one of the at least one characteristic curves which reflects the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the respective LED light source (4, 5, 6) or the dependence of the dominant wavelength of the light generated by that LED light source (4, 5, 6) on the temperature of the arrangement (2), wherein in each case during the operation of the arrangement (2) the one of the at least one characteristic curves is used to compensate for a temperature-dependent change in the dominant wavelength of the light generated by the respective LED light source (4, 5, 6).
7. System (1) according to Claim 5 or 6, characterized in that the LED light sources (4, 5, 6) of the arrangement comprise

   - at least one LED light source (4) configured to generate blue light, which has at least one light-emitting diode,

   - at least one LED light source (5), designed to generate conversion light with a colour located in a conversion range, which has at least one light-emitting diode configured to generate blue light and at least one conversion unit configured for photoluminescence, and/or

   - at least one LED light source (6) configured to produce red or green light, which has at least one light-emitting diode.

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