WO2011070494A2

WO2011070494A2 - User interface for multi-color led system to set color point and spectrum independently

Info

Publication number: WO2011070494A2
Application number: PCT/IB2010/055573
Authority: WO
Inventors: Stefan Marcus Verbrugh; Reinhard Ruben Voorspoels; Willem Christiaan Van Abkoude; Petrus Johannes Mathijs Van Der Burgt; Ralph Kurt
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2009-12-09
Filing date: 2010-12-03
Publication date: 2011-06-16
Also published as: WO2011070494A3

Abstract

A method and a controller for controlling properties of light emitted from a light-emitting device comprising a plurality of light sources, each of the light sources being configured to emit light within a predetermined wavelength range, are disclosed. The intensities of the plurality of light sources included in the light-emitting device are adjusted by means of two independent steps. In a first step, a color point of the available color points of light emitted from the light-emitting device is selected. In a second step, one or more settings for the intensities of the plurality of light sources relatively to each other are selected. The one or more settings are selected from settings, each of which settings, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the color point selected in the first step.

Description

User interface for multi-color LED system to set color point and spectrum independently

FIELD OF THE INVENTION

The present invention generally relates to the field of lighting. In particular, the present invention relates to a controller for controlling properties of a light-emitting device comprising a plurality of light sources, each of the light sources being configured to emit light within a predetermined wavelength range.

BACKGROUND OF THE INVENTION

Light is composed of electromagnetic waves having various wavelengths within a wavelength range of about 400 nm to about 700 nm. Each electromagnetic wave having a wavelength within this range produces light exhibiting a distinct color of light, from deep blue/purple at a wavelength of about 400 nm to deep red at a wavelength of about 700 nm. By "mixing" electromagnetic waves having different wavelengths light exhibiting various colors can be produced.

Light-emitting devices comprising a number of light sources, each light source being capable of emitting light that in general has a different color compared to the other light sources, may be utilized to provide light having a variety of colors. For example, a light- emitting diode (LED) device comprising three LEDs emitting light in different wavelength ranges (i.e. exhibiting different colors) can be utilized to provide light having virtually any color point within the triangle in a color space, for example in a chromaticity diagram, defined by three color points of the respective LEDs. By adjusting the light flux levels of the LEDs (i.e. currents through the respective LEDs) relatively to each other appropriately, there can be achieved light emitted from the LED device having different color points and/or light spectra.

Different techniques are known for classifying light. An example is the use of color temperature. The color temperature of a light source is determined by comparing the chromaticity of the light source with the chromaticity of an ideal black-body radiator. The temperature at which the black-body radiator matches the color of the light source is taken as the color temperature of the light source. The black body locus (BBL) (also known as Planckian locus, or white line) is the path or locus that the color of an incandescent black body would take in a particular chromaticity space (e.g., in a chromaticity diagram) as the temperature of the black body changes. The locus goes from deep red at relatively low temperatures (at about 700 K), on through orange, yellowish white, white, and finally bluish white at higher temperatures.

In a number of applications, such as in retail lighting and entertainment lighting, a large variety of colors are in general employed and the precise color and the spectrum of the light may be in general important. Especially in theatrical lighting applications the spectral quality of colored light is important. In such applications the light is generally used to illuminate objects and people. The appearance of these objects and persons (e.g., skin tones of the persons) may be important. Even if the color point of the light used for illumination is not located on the BBL, the appearance of different colors on objects (caused by wavelength dependent reflection) may be important. For example, in such applications a lighting designer may want to create a desired lighting effect apart from merely making the object or person visible as is done with white light.

For entertainment lighting fixtures, it is known to include a filter between a light-emitting device (e.g., a lamp) and the object or person to be illuminated in order to adjust the spectral content of the light used for illumination. According to one approach so called gel filters are employed, which block part of the light spectrum and transmit another part of the light spectrum. Typically, the part of the spectrum (i.e. the wavelength range) of the light that is transmitted is relatively wide and comprises more than one color. A selection of color is made by the user selecting the appropriate gel filter and arranging it in front of the lamp or by the user operating an automated system for selecting one filter to be placed in front of the lamp out of several filters. According to another approach dichroic filters are employed. Dichroic filters comprise multiple layers or films for creating wavelength dependent reflection and transmission. In other words, dichroic filters are color filters used to selectively pass light of a small range of colors while reflecting other colors. A mechanism for shifting the position of the dichroic filter in a controlled manner may enable an in principle continuous color adjustment of the light.

SUMMARY OF THE INVENTION

Especially in a theatrical environment, there is often a relatively large variety of objects on a stage, with an even larger variety of colors. Such objects may for example comprise the costumes of actors, portions of the scenery and faces of the actors. With an illumination of the objects other than with white light, some of the objects may be more visually accentuated than other objects as compared to illumination with white light, and some other objects may be less visually emphasized as compared to illumination with white light, as perceived by the viewer, depending on the spectral content of the light used for illumination and the spectral reflectance of the color of the objects.

When employing gel filters or dichroic filters, each filter is associated with a specific relation between the total color impression of the illuminated area on the stage and what object or objects are and are not visually emphasized in the illuminated area on the stage. For a particular stage, on which there in general is a relatively large variety of objects on a stage with an even larger variety of colors, it would be a demanding or even

prohibitively time-consuming work to choose two or more filters such that each of the chosen filters provides the same (or similar) total color impression of the illuminated area on the stage but visually emphasizes a particular object or objects differently with respect to the other filter(s). This is further discussed in the following.

Firstly, when employing gel filters for adjusting the spectral content of the light used for illumination, the user (e.g., a lighting designer) typically has to know from experience which filter that yields the desired effect. Gaining that experience, by placing different filters in front of the lamp and examining the effect of the different filters on the spectral content of the light used for illumination, may be time consuming and demanding work as it entails physically placing each of the different filters between the lamp and the object(s) or person(s) to be illuminated and examining the effect of each filter on the spectral content of the light used for illumination.

Secondly, dichroic filters may enable a user to select the desired color point of the light used for illumination. However, the appearance of the object(s) or person(s) (e.g., skin tones of the persons) to be illuminated is determined by the nature of the filter that is used and the spectrum of the light emitted from the lamp. Mechanisms for controlling the color using a set of dichroic filters are in general relatively complex, expensive and/or sensitive to failures (e.g., because of the heat generated by operation of the lamp).

It is with respect to the above considerations and others that the present invention has been made. In particular, the inventors have realized that it would be desirable to achieve a method and a controller for controlling properties of light emitted from a light- emitting device comprising a plurality of light sources such as to enable a user to browse through many settings of the intensities of the plurality of light sources relatively to each other, at a fixed color point that has been selected by the user, while concurrently being able to view the results corresponding to the respective settings. To better address one or more of these concerns, a controller and a method for controlling properties of light emitted from a light-emitting device having the features defined in the independent claims are provided. Further advantageous embodiments of the present invention are defined in the dependent claims.

The present invention is based on employing a controller, comprising a user interface and a processing unit, for adjusting the intensities of the plurality of light sources included in the light-emitting device by means of two independent steps. In a first step, a color point of the available color points of light emitted from the light-emitting device is selected. This color point may either be white light (i.e. having a color point situated on the black body locus (BBL)) or non- white light (i.e. having a color point situated off the BBL). In a second step, one or more settings for the intensities of the plurality of light sources relatively to each other are selected. The one or more settings are selected from settings, each of which settings, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the color point selected in the first step. The second step may enable the user to browse through different settings at a fixed color point (as set in the first step) while concurrently being able to view the results corresponding to the respective settings.

According to a first aspect of the present invention, there is provided a controller adapted to control properties of light emitted from a light-emitting device comprising a plurality of light sources, each of the light sources being configured to emit light within a predetermined wavelength range. The controller comprises a user interface (UI) and a processing unit (PU). The UI is adapted to enable a user to select at least one color point of the available color points of light emitted from the light-emitting device, whereby the controller is provided with first user input. The available color points of the light emitted by the light-emitting device are based on the wavelength ranges of the respective light sources. The PU is adapted to generate a plurality of first settings of the intensities of the plurality of light sources relatively to each other, wherein each setting of said plurality of first settings, when applied to the plurality of light sources, results in that light emitted from the light-emitting device exhibits the selected color point. The UI is further adapted to enable the user to select at least one setting of the plurality of first settings, whereby the controller is provided with second user input. The PU can be further adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the second user input in accordance with the selected at least one setting of the plurality of first settings. Such a configuration may facilitate or even enable the user to browse through many settings of the intensities of the plurality of light sources relatively to each other, at a fixed color point selected by the user, while concurrently being able to view the results corresponding to the respective settings. In other words, during the browsing the controller may adapt the setting of the light source intensities relatively to each other substantially instantaneously as soon as a new setting is selected or indicated by the user, which may provide the user with a "what-you-see-is-what-you-get" procedure for controlling properties of light emitted from the light-emitting device.

Such a configuration may enable the user (e.g., a lighting designer) to create two or more different settings of the light source intensities relatively to each other that results in similar or identical general color impressions (atmospheres) as perceived by a viewer, but visually highlighting or emphasizing different objects in the illuminated area (or such that each setting of the light source intensities relatively to each other enables visually highlighting or emphasizing a particular object or objects differently with respect to the other setting(s)).

An example of how the present invention may be used is given in the following. Consider the scenario of several persons (actors) present on a stage, which actors are illuminated by the light-emitting device. The actors are acting out a play on the stage, and wear costumes having different colors. The background of the stage contains objects having neutral colors (e.g., white). One of the actors has a red costume. Also, assume that the lighting designer for example has chosen light having a light color having a color point close to the BBL for illuminating the stage. During a certain passage in the play the lighting designer may not wish to visually emphasize or highlight the person actor in the red costume. Thus, at a first stage in the play when the actor wearing the red costume has only a minor part in the play, the lighting designer, having prior to the play browsed through many settings of the intensities of the plurality of light sources relatively to each other for the present color point, may choose one of the settings of the intensities of the light sources relatively to each other such that the red costume is less well rendered compared to other settings. In this manner, the red costume (and hence, the actor wearing the red costume) is less visually emphasized compared to other objects and/or persons on the stage. At a later, second stage in the play, when the actor wearing the red costume has a larger (more prominent) part in the play, the lighting designer may choose one of the settings of the intensities of the light sources relatively to each other such that the red costume is relatively well rendered compared to other settings, such that the red costume is visually emphasized or highlighted (e.g., such that the visibility of the red costume is increased). Thus, the light illuminating the stage results in similar or identical general color impressions (atmospheres) as perceived by a viewer at both the first and the second stage in the play, but visually highlights or emphasizes different objects in the illuminated area on the stage at the different stages in the play. In other words, the lighting designer may noticeably change the rendering of the red costume between the first and the second stage as perceived by the viewer, while only changing the appearance of other objects and/or persons on the stage relatively little or even negligible between the first and second stage in the play.

The UI may be further adapted to indicate the available color points of light emitted from the light-emitting device to the user. Such indication can for example be visual and/or auditory. Such visual indication may for example be presented to the user by means of a display screen.

According to an exemplifying embodiment, the visual indication may comprise a color diagram, also known as a color triangle, and/or a portion of the color diagram, e.g. a zoomed in portion of the color diagram covering portions of the BBL or a zoomed in portion of the color diagram comprising the currently selected color point.

According to another exemplifying embodiment, the visual indication may comprise a digital/numeric indication, e.g. the currently selected intensities of each of the different light sources (color channels) as a fraction of the maximum intensity of the respective light source. According to the exemplifying embodiment the number of color channels is at least three. The visual indication may comprise an indication of the ranges within which the intensity levels of the respective individual color channels can be varied, while keeping both the color point and the total light intensity at the predefined/user-defined levels.

The LEDs may for example have a white (W), red (R), green (G), blue (B) or amber (A), cyan (C), deep red (dR) and/or deep blue (dB) emission spectrum. White can be warm white (WW), neutral white (NW) and/or cool white (CW). By combination of LEDs having different emission spectra such as presented above, in principle any desired light spectrum may be achieved that falls within the color space defined by the color coordinates of the WRGBAdRdB LEDs.

According to another exemplifying embodiment the light-emitting device may comprise a plurality of light sources having colors such as (RGBW), (RGB + WW), (RGBA), (RGBAW), (RGB AC), (RGBAdR), (RGBACdR), (RGBACdRW), (RGBACdRdB), etc. The available color points of light emitted from the light-emitting device may be generated, for instance by the PU, on the basis of the wavelength ranges of the respective light sources of the light-emitting device. For this purpose, the controller may comprise a communication unit (CU) adapted to receive a plurality of wavelength control signals from the light source, each wavelength control signal being indicative of the predetermined wavelength range of light emitted by a respective light source.

The UI may be further adapted to indicate the plurality of first settings to the user. Such indication can for example be visual and/or auditory.

Alternatively, instead of the PU a CU may be adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the second user input in accordance with the selected at least one setting of the plurality of first settings, for example by means of communicating to the light source control signals corresponding to the second user input in accordance with the selected at least one setting of the plurality of first settings.

According to a second aspect of the present invention, there is provided a method of operating a light-emitting device that comprises a plurality of light sources, each of which is being configured to emit light within a predetermined wavelength range. The method comprises enabling a user to select by means of first user input at least one color point of the available color points of light emitted from the light-emitting device. The available color points are based on the wavelength ranges of the respective light sources. The method comprises generating a plurality of first settings of the intensities of the plurality of light sources relatively to each other, wherein each setting of the plurality of first settings, when applied to the plurality of light sources, results in that light emitted from the light- emitting device source exhibits the selected color point. The method comprises enabling the user to select at least one of the plurality of first settings by means of second user input. On the basis of the second user input, the intensities of the plurality of light sources relatively to each other are adjusted in accordance with the selected at least one setting of the plurality of first settings.

Such a method may enable achieving the same or similar advantages as the advantages achieved by the controller according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a computer program product adapted to, when executed in a processor unit, perform a method according to the second aspect of the present invention or any embodiment thereof. According to a fourth aspect of the present invention, there is provided a computer-readable storage medium on which there is stored a computer program product adapted to, when executed in a processor unit, perform a method according to the second aspect of the present invention or any embodiment thereof.

According to a fifth aspect of the present invention, there is provided a luminaire comprising a light-emitting device that comprises a plurality of light sources, each of the light sources being configured to emit light within a predetermined wavelength range. The luminaire further comprises a controller according to the first aspect of the present invention or any embodiment thereof, the controller being adapted to control properties of light emitted from the light-emitting device.

The plurality of light sources preferably comprises a plurality of solid-state light sources, such as light-emitting diodes (LEDs). Such LEDs may be inorganic or organic. Moreover, such LEDs may be selected from the group comprising AlInGaP and InGaN based LEDs, direct emitting LEDs, partially and full phosphor converted LEDs.

According to an embodiment of the present invention a combination of direct emitting LEDs and phosphor converted LEDs may be used. In other words, LEDs having a relatively narrow emission spectrum may be used in combination with LEDs having a relatively broad emission spectrum.

The PU may be adapted to generate a second setting of the intensities of the plurality of light sources relatively to each other such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point. The PU may be adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the second setting.

In other words, after the user has selected the desired color point, the controller may adjust the intensities of the plurality of light sources relatively to each other such that light emitted from the light-emitting device exhibits the selected color point. This may be performed basically immediately following the selection of the desired color point, before the user browses other settings by means of second user input, as described in the foregoing. Such a configuration enables selecting a "default" setting for the intensities of the plurality of light sources relatively to each other. The default setting may for example be adapted to user, lighting design and/or application requirements. Examples of such default settings are described in the following.

According to one example, if the light-emitting device comprises at least five light sources emitting light within at least five distinct wavelength ranges and on a condition that the selected at least one color point is situated on the BBL, the PU may be adapted to generate a second setting of the intensities of the plurality of light sources relatively to each other such that the color rendering index (CRI) for the light emitted by the light-emitting device is at a maximum and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point. The PU may be adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the second setting.

For example, in case the light-emitting device comprises five light sources emitting light within five distinct wavelength ranges (i.e. providing five 'degrees of freedom' for adjusting the color and/or spectra of light emitted by the light-emitting device), the intensities of three of the light sources relatively to each other may be adjusted such that light emitted from the light-emitting device exhibits the selected color point. The intensity of one of the other light sources relatively the other may then be adjusted so as to adjust the CRI for the light emitted by the light-emitting device, and the intensity of the last remaining light source relatively the other may be adjusted such as to adjust the color impression

(atmosphere) resulting from illuminating an object or a location as perceived by a viewer.

According to one example there may be provided default preset values for the first settings after the second settings have been set. These default preset values are such that, when the default preset values are applied to the plurality of light sources, the highest CRI when compared to other settings of the intensities of the plurality of light sources relatively to each other is obtained at the selected color point and the required total lumen output from the light-emitting device is obtained.

In other words, the PU may be adapted to generate a second setting of the intensities of the plurality of light sources relatively to each other such that the color rendering index for the light emitted by the light-emitting device has a value that is the highest when compared to other settings of the intensities of the plurality of light sources relatively to each other, while conserving the selected color point of light emitted from the light-emitting device.

According to one example, the PU may be adapted to generate default preset values of the intensities of the plurality of light sources relatively to each other such that, when the default preset values are applied to the plurality of light sources, the light intensities of the different color channels are set such that spectrally a relatively close match or even the best match with one of the known conventional gel spectra (i.e. spectra resulting from utilizing conventional gel filters) is obtained with respect to the light output from the light- emitting device. At the same time the selected color point is kept substantially constant or even fixed and the color point of the closest gel spectra is mimicked. In this manner color effects such as known in the art (using conventional gel filters) can be achieved.

According to another example, on a condition that the selected at least one color point is situated off the BBL, the PU may be adapted to generate a second setting of the intensities of the plurality of light sources relatively to each other such that the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum, and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point. The PU may be adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the second setting.

In other words, the PU may be adapted to generate a second setting of the intensities of the plurality of light sources relatively to each other such that the difference between the contributions to the total luminous flux of the light-emitting device from each light source is the lowest when compared to other settings of the intensities of the plurality of light sources relatively to each other, while conserving the selected color point of light emitted from the light-emitting device.

By setting the intensities of the plurality of light sources relatively to each other such that the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum, the rendering of colors of the object(s) illuminated by the light-emitting device may be increased.

In the context of some embodiments of the present invention, by the term "luminous flux" of the light-emitting device it is referred to the total light power emitted by the light-emitting device.

The UI may be adapted to enable a user to select the total light output of the light-emitting device by means of the first user input or other user input, for example on basis of user, capacity or application requirements. On the basis of the user input, the PU may be adapted to adjust the intensities of the plurality of light sources such that the selected total light output of the light-emitting device is achieved.

The UI may be adapted to enable a user to select at least one of the wavelength ranges. The PU may be adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other under the constraint of keeping the intensity of the light source associated with the selected at least one wavelength range constant and/or different from zero. In other words, the UI may enable the user to select one or more of the light sources, whose intensity or intensities are fixed at some value, after which the controller may generate the plurality of first settings of the light sources relatively to each other while keeping the intensity or intensities of the selected one or more light sources at the fixed value.

Such a configuration enables to even further visually emphasize or highlight an object or a person having a certain color, the object or person being illuminated by light from the light-emitting device. This is further described with reference to the following example.

According to one example, the user has selected a color point that is close to the BBL, such that light having a light color or a substantially white color is used for illuminating the object or person. The object or person has a certain color that in general is different from the color of the light illuminating the object or person. The intensity of a selected light source, emitting light having a color point close or equal to the color point of the color of the object or person, may be kept at a fixed value while generating the plurality of first settings of the light sources relatively to each other. In other words, the plurality of first settings may be generated such that the light of the light-emitting device is a mixture of light having different color points, wherein the mixture of light includes a proportion of light having a color point close to or equal to the color point of the color of the object or person (for example, white light used for illuminating the object or person, which has a red color, is mixed with a proportion of light having a color point close to or equal to red). As a result, the resulting mixture of light may even further visually emphasize or highlight the object or person.

The UI may be further adapted to indicate the wavelength ranges to the user. Such indication can for example be visual and/or auditory.

The PU may be adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the total flux of the light emitted by the light-emitting device is at a maximum or the energy efficiency of the light-emitting device is at a maximum.

In other words, the PU may be adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the total flux of the light emitted by the light-emitting device or the energy efficiency of the light-emitting device is the highest when compared to other settings of the intensities of the plurality of light sources relatively to each other.

On a condition that the light-emitting device comprises at least five light sources emitting light within at least five distinct wavelength ranges, the PU may be adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the total flux of the light emitted by the light-emitting device and the energy efficiency of the light-emitting device is the highest when compared to other settings of the intensities of the plurality of light sources relatively to each other.

Such a configuration may enable generating a plurality of first settings adapted to user, lighting design and/or application requirements. Examples of such settings are described in the following.

According to one example, the PU may be adapted to, if the light-emitting device comprises at least five light sources emitting light within at least five distinct wavelength ranges and if the selected at least one color point is situated on the BBL, generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the color rendering index for the light emitted by the light-emitting device is at a maximum.

In other words, the PU may be adapted to, if the light-emitting device comprises at least five light sources emitting light within at least five distinct wavelength ranges and if the selected at least one color point is situated on the BBL, generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the color rendering index for the light emitted by the light-emitting device has a value that is the highest when compared to other settings of the intensities of the plurality of light sources relatively to each other.

According to another example, the PU may be adapted to, if the selected at least one color point is situated off the BBL, generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum. In other words, the PU may be adapted to, if the selected at least one color point is situated on the BBL, generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the difference between the contributions to the total luminous flux of the light-emitting device from each light source is the lowest when compared to other settings of the intensities of the plurality of light sources relatively to each other.

The PU may be adapted to detect a change in at least one operation parameter of a respective light source, by comparing the at least one operation parameter with a previous value of at least one operation parameter of the respective light source. The PU may be adapted to, on a condition that a change is detected, on the basis of the change generate a new at least one operation parameter for the respective light source such that, when the new at least one operation parameter is applied to the respective light source, the at least one selected color point is approximately maintained or conserved. The PU may be adapted to adjust the at least one operation parameter of the respective light source in accordance with the new at least one operation parameter.

By such a configuration the selected color point can be approximately maintained or even conserved by a operation parameter feedback arrangement in case of sudden disturbances or gradual changes occurring internally or externally with respect to the light-emitting device that may have an impact on the operation of the light-emitting device, for example a relatively large temperature change in the surroundings of the light-emitting device, material changes in the light sources affecting the operation of the light sources due to aging thereof, etc.

For example, the PU may be configured such as to maintain the selected color point in case of changes in one or more operation parameters of a respective light source within a predetermined fraction of the value of the current color point, for example within about 5 MacAdam ellipses, or color ovals, of the value of the current color point.

In the context of some embodiments of the present invention, by a MacAdam ellipse it is referred to a region on a chromaticity diagram that comprises all colors that are indistinguishable to an observer from the color at the center of the region.

The controller may comprise a memory unit for storing at least one setting of the plurality of first settings. The UI may be adapted to enable the user to select at least one setting of the stored at least one setting of the plurality of first settings, whereby the controller is provided with third user input. The PU may be adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of the third user input in accordance with the selected at

By such a configuration, a user may store a set including one or more first settings and later recall any one of the stored first settings and apply the recalled setting to the plurality of light sources.

The light-emitting device may comprise at least three light sources, the light sources being configured such that at least three of the light sources emit light within different wavelength ranges relatively to each other. Such a configuration can be utilized to provide light having virtually any color point within the triangle in a color space, for example in a CIE chromaticity diagram, defined by three color points of the respective light sources. By adjusting the intensities of the light sources relatively to each other (e.g., in case the light source comprises a LED, by modulating the current through the LED) appropriately, light emitted from the light-emitting device having different color points and/or light spectra can be achieved.

Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments.

It is noted that the present invention relates to all possible combinations of features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

Exemplifying embodiments of the present invention will be described in the following with reference to the other accompanying drawings, in which:

Fig. 1 A is a schematic block diagram of a controller according to an exemplifying embodiment of the present invention for controlling properties of light emitted from a light-emitting device; and

Fig. IB is a schematic block diagram of a luminaire according to an exemplifying embodiment of the present invention, the luminaire comprising a light-emitting device and a controller according to the embodiment described with reference to Fig. 1 A for controlling properties of light emitted from the light-emitting device;

Fig. 2 is a schematic flow diagram of a method of controlling properties of light emitted from a light-emitting device according to an exemplifying embodiment of the present invention; and

Fig. 3 is a schematic view of different exemplifying types of computer readable storage mediums according to embodiments of the present invention. In the accompanying drawings, the same reference numerals denote the same or similar elements throughout the views.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the invention are shown. This present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. Furthermore, like numbers refer to like or similar elements or components throughout. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Referring now to Fig. 1A, there is shown a schematic block diagram of a controller 100 according to an exemplifying embodiment of the present invention for controlling properties of light emitted from a light-emitting device 150, comprising a plurality 160 of light sources 170A, 170B, 170F. The controller 100 comprises a user interface (UI) 110 and a processing unit (PU) 120. As indicated in Fig. 1A, the UI 110 and the PU 120 may communicate with each other, and each of the UI 110 and the PU 120 may communicate signals to, and receive signals from, the light-emitting device 150. According to the embodiment depicted in Fig. 1A, each of the UI 110 and the PU 120 may communicate signals to, and receive signals from, the plurality 160 of light sources 170A, 170B, ..., 170F directly. The controller 100 further comprises a memory unit 140 (optional) for storing data.

The number of light sources in the light-emitting device is not limited to six as depicted in Fig. 1 A but the number of light sources may be in principle any number, for example three, five, seven, eight or ten.

The communication back and forth between the controller 100 and the light- emitting device 150 may be wired or wireless.

Referring now to Fig. IB, there is shown a schematic block diagram of a luminaire 180 according to an exemplifying embodiment of the present invention. The luminaire 180 comprises a light-emitting device 150 and a controller 100 in accordance with the embodiment described with reference to Fig. 1A for controlling properties of light emitted from the light-emitting device 150.

The operation of the controller 100 is described in the following with reference to Fig. 2. Referring now to Fig. 2, there is shown a schematic flow diagram of a method of operating a light-emitting device, the light-emitting device comprising a plurality of light sources, each of which is being configured to emit light within a predetermined wavelength range.

At step 210, a user is enabled to select at least one color point of the available color points of light emitted from the light-emitting device by means of a first input. The available color points are based on the wavelength ranges of the respective light sources.

At step 220, a plurality of first settings of the intensities of the plurality of light sources relatively to each other is generated. The plurality of first settings is generated such that each setting of the plurality of first settings when applied to the plurality of light sources, results in that light emitted from the light-emitting device source exhibits the color point that was selected at step 210.

At step 230, the user is enabled to select at least one of the plurality of first settings by means of second user input.

At step 240, the intensities of the plurality of light sources relatively to each other are adjusted on the basis of the second user input provided at step 230, in accordance with the selected at least one setting of the plurality of first settings.

Optionally, the method 200 may comprise a step 215. At step 215, a second setting of the intensities of the plurality of light sources relatively to each other is generated. The second setting is generated such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the color point selected at step 210. The intensities of the plurality of light sources relatively to each other are subsequently adjusted on the basis of the second setting.

Optionally, with reference to step 215, on a condition that the at least one color point selected at step 210 is situated on the black body locus (BBL), the second setting of the intensities of the plurality of light sources relatively to each other may be generated such that the color rendering index for the light emitted by the light-emitting device is at a maximum and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the color point selected at step 210.

Optionally or alternatively, with further reference to step 215, on a condition that the at least one color point selected at step 210 is situated off the BBL, the second setting of the intensities of the plurality of light sources relatively to each other may be generated such that the difference between the contributions to the total luminous flux of the light- emitting device from each light source is at a minimum and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light- emitting device exhibits the color point selected at step 210.

The step 220 may optionally comprise a step 222, comprising enabling the user to select at least one of the wavelength ranges associated with the respective light sources and generating the plurality of first settings of the intensities of the plurality of light sources relatively to each other under the constraint of keeping the intensity of the light source associated with the selected at least one wavelength range constant and/or different from zero.

Optionally or alternatively, a step 224 may be performed, comprising generating the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the flux of the light emitted by the light-emitting device is at a maximum and/or the efficiency of the light-emitting device is at a maximum.

Optionally, with reference to step 224, on a condition that the at least one color point selected at step 210 is situated on the BBL, the plurality of first settings of the intensities of the plurality of light sources relatively to each other may be generated such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the color rendering index for the light emitted by the light-emitting device is at a maximum.

Optionally or alternatively, with further reference to step 224, on a condition that the at least one color point selected at step 210 is situated off the BBL, the plurality of first settings of the intensities of the plurality of light sources relatively to each other may be generated such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum.

Optionally, the method 200 may comprise a step 226. Step 226 comprises detecting a change in at least one operation parameter of a respective light source, by comparing the at least one operation parameter with a previous value of at least one operation parameter of the respective light source. The step 226 further comprises, on a condition that a change is detected, generating a new at least one operation parameter for the respective light source on the basis of said change. The new at least one operation parameter is generated such that, when the new at least one operation parameter is applied to the respective light source, the at least one selected color point is approximately maintained or even conserved. Subsequently, the at least one operation parameter of the respective light source is adjusted in accordance with the new at least one operation parameter.

Optionally, the method 200 may comprise a step 235. Step 235 comprises enabling the user to select at least one setting of a stored at least one setting of a plurality of first settings by means of third user input. Subsequently, the intensities of the plurality of light sources relatively to each other are adjusted on the basis of the third user input in accordance with the selected at least one setting of the stored at least one setting of the plurality of first settings.

The plurality of light sources of the light-emitting device may according to an embodiment comprise colored LEDs, according to one example LEDs emitting light of color red, green, blue, cyan, amber and white, respectively. The set of available color points can be visualized as the color points situated within an area defined by a polygon in a chromaticity diagram, where each corner (vertex) in the polygon is defined by a color point of a respective colored LED. The user may then select one color point of the available color points, which color point may be situated on or off the BBL. After the user has selected the color point, the controller may then adjust the setting of the intensity for at least two light sources relatively to each other in order to maintain the selected color point for light emitted by the light- emitting device. For this purpose, the user may indicate by means of user input on the UI which at least two light sources whose intensities relatively to each other should be adjusted. Subsequently, the user may browse through the resulting settings and select the setting which yields the desired spectra of the light emitted by the light-emitting device.

Referring now to Fig. 3, there are shown schematic views of computer readable (digital) storage mediums 300 according to exemplifying embodiments of the present invention, comprising a Digital Versatile Disc (DVD) 310 and a floppy disk 320. On each of the DVD 310 and the floppy disk 320 there may be stored a computer program comprising computer code adapted to perform, when executed in a processor unit, a method according to the present invention or any embodiment thereof, as has been described in the foregoing.

Although only two different types of computer-readable digital storage mediums have been described above with reference to Fig. 3, the present invention encompasses embodiments employing any other suitable type of computer-readable digital storage medium, such as, but not limited to, a hard disk drive, a Compact Disc, a flash memory, magnetic tape, a Universal Serial Bus stick, a Zip drive, etc. In conclusion, a method and a controller for controlling properties of light emitted from a light-emitting device comprising a plurality of light sources have been disclosed, each of the light sources being configured to emit light within a predetermined wavelength range. The intensities of the plurality of light sources included in the light- emitting device are adjusted by means of two independent steps. In a first step, a color point of the available color points of light emitted from the light-emitting device is selected. In a second step, one or more settings for the intensities of the plurality of light sources relatively to each other are selected. The one or more settings are selected from settings, each of which settings, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the color point selected in the first step.

While the invention has been illustrated and described in detail in the appended drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplifying and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A controller (100) adapted to control properties of light emitted from a light- emitting device (150) comprising a plurality (160) of light sources (170), each of the light sources being configured to emit light within a predetermined wavelength range, the controller comprising:

a user interface (110), UI; and

a processing unit (120), PU;

the UI being adapted to enable a user to select at least one color point of the available color points of light emitted from the light-emitting device, the available color points being based on the wavelength ranges of the respective light sources, whereby the controller is provided with first user input;

the PU being adapted to generate a plurality of first settings of the intensities of the plurality of light sources relatively to each other, wherein each setting of said plurality of first settings, when applied to the plurality of light sources, results in that light emitted from the light-emitting device exhibits the selected color point;

the UI being further adapted to enable the user to select at least one setting of the plurality of first settings, whereby the controller is provided with second user input; and the PU being further adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of said second user input in accordance with the selected at least one setting of the plurality of first settings.

2. A controller according to claim 1, wherein the PU is further adapted to:

generate a second setting of the intensities of the plurality of light sources relatively to each other such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point; and

adjust the intensities of the plurality of light sources relatively to each other on the basis of said second setting.

3. A controller according to claim 1, wherein the light-emitting device comprises at least five light sources emitting light within at least five distinct wavelength ranges and wherein, on a condition that the selected at least one color point is situated on the black body locus, the PU is further adapted to:

generate a second setting of the intensities of the plurality of light sources relatively to each other such that the color rendering index for the light emitted by the light- emitting device is at a maximum and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point; and

4. A controller according to claim 1, wherein, on a condition that the selected at least one color point is situated off the black body locus, the PU is further adapted to:

generate a second setting of the intensities of the plurality of light sources relatively to each other such that the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum and such that the second setting, when applied to the plurality of light sources, results in that the light emitted from the light-emitting device exhibits the selected color point; and

adjust the intensities of the plurality of light sources on the basis of said second setting.

5. A controller according to claim 1, wherein:

the UI is further adapted to enable a user to select at least one of the wavelength ranges; and

the PU is further adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other under the constraint of keeping the intensity of the light source associated with the selected at least one wavelength range constant and/or different from zero.

6. A controller according to claim 1 or 5, wherein the PU is further adapted to generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources: the total flux of the light emitted by the light-emitting device is at a maximum; or

the energy efficiency of the light-emitting device is at a maximum.

7. A controller according to claim 1 or 5, wherein the light-emitting device comprises at least five light sources emitting light within a at least five distinct wavelength ranges and wherein, on a condition that the selected at least one color point is situated on the black body locus, the PU is further adapted to:

generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the color rendering index for the light emitted by the light-emitting device is at a maximum.

8. A controller according to claim 1 or 5, wherein, on a condition that the selected at least one color point is situated off the black body locus, the PU is further adapted to:

generate the plurality of first settings of the intensities of the plurality of light sources relatively to each other such that, when each setting of the plurality of first settings is applied to the plurality of light sources, the difference between the contributions to the total luminous flux of the light-emitting device from each light source is at a minimum.

9. A controller according to claim 1, wherein the PU is further adapted to detect a change in at least one operation parameter of a respective light source by comparing said at least one operation parameter with a previous value of at least one operation parameter of the respective light source, and, on a condition that a change is detected, on the basis of said change generate a new at least one operation parameter for the respective light source such that, when the new at least one operation parameter is applied to the respective light source, the at least one selected color point is conserved, the PU being further adapted to adjust the at least one operation parameter of the respective light source in accordance with said new at least one operation parameter.

10. A controller according to claim 1, further comprising a memory unit (130) for storing at least one setting of the plurality of first settings, the UI being further adapted to enable the user to select at least one setting of the stored at least one setting of the plurality of first settings, whereby the controller is provided with third user input, the PU being further adapted to adjust the intensities of the plurality of light sources relatively to each other on the basis of said third user input in accordance with the selected at least one setting of the stored at least one setting of the plurality of first settings.

11. A method (200) of controlling properties of light emitted from a light-emitting device comprising a plurality of light sources, each of the light sources being configured to emit light within a predetermined wavelength range, the method comprising:

enabling (210) a user to select at least one color point of the available color points of light emitted from the light-emitting device, the available color points being based on the wavelength ranges of the respective light sources, by means of first user input;

generating (220) a plurality of first settings of the intensities of the plurality of light sources relatively to each other, wherein each setting of said plurality of first settings, when applied to the plurality of light sources, results in that light emitted from the light- emitting device source exhibits the selected color point;

enabling (230) the user to select at least one of the plurality of first settings by means of second user input; and

adjusting (240) the intensities of the plurality of light sources relatively to each other on the basis of said second user input in accordance with the selected at least one setting of the plurality of first settings.

12. A computer program product adapted to, when executed in a processor unit, perform a method according to claim 11.

13. A computer-readable storage medium (300) on which there is stored a computer program product adapted to, when executed in a processor unit, perform a method according to claim 11.

14. A luminaire (180), comprising:

a light-emitting device (150) comprising a plurality (160) of light sources

(170), each of the light sources being configured to emit light within a predetermined wavelength range; and

a controller (100) according to any one of claims 1-10 adapted to control properties of light emitted from the light-emitting device.

15. A luminaire according to claim 14, wherein the light-emitting device comprises at least three light sources and the light sources are configured such that at least three of the light sources emit light within different wavelength ranges relatively to each other.