WO2023072927A1

WO2023072927A1 - Light device

Info

Publication number: WO2023072927A1
Application number: PCT/EP2022/079775
Authority: WO
Inventors: Chento Didden
Original assignee: Summa Ip B.V.
Priority date: 2021-10-29
Filing date: 2022-10-25
Publication date: 2023-05-04
Also published as: NL2029552B1

Abstract

According to the invention, a light device (100) configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the light device comprises: at least three LEDs each having distinct radiation patterns together forming the mimicked black-body radiation, wherein the at least three radiation patterns define a convex polygon surrounding a locus curve section of the locus curve defined by the body temperature range; a controller (110) configured for: receiving an input associable with a set body temperature; translating the input to a LED setting for each of the at least three LEDs; and setting the at least three LEDs according to the LED settings; and wherein the convex polygon snugly fits around the locus curve section.

Description

LIGHT DEVICE

FIELD OF THE INVENTION

The invention relates to a light device having at least three LEDs. The invention relates more specifically to mimicking black-body radiation with the at least three LEDs. The invention further relates to a method for producing the light device, and a method for producing sets of LEDs. The invention further relates to a data processing system and a computer-readable storage medium.

BACKGROUND OF THE INVENTION

Conventional light, such as light bulbs, can be switched on and off. When on, these light bulbs radiate a particular light. Advancements in technology have provided LEDs in the colours red, green, yellow, blue. Combinations of these primary colour LEDs are used for providing a combined radiated spectrum. The combined radiated spectrum is typically some sort of white light. The colour of the combined radiated spectrum may be changed by adjusting the power to one or more of these LEDs. A disadvantage of these combinations of these primary colour LEDs is that the light radiate spectrum is not very stable, the radiated spectrum is typically some white colour, and the efficiency in producing some white colour may be improved.

US 8,928,249 B2 discloses a system provides White light having a selectable spectral characteristic (e.g. a selectable color temperature, delta uv, and intensity) using a combination of sources (e.g. LEDs) emitting light ofthree, four, five, or six different characteristics, for example, one or more White LEDs, and one or more LEDs of each of three primary colors, plus cyan and royal blue. A controller maintains a desired spectral characteristic, e.g. for White light at a selected point on or Within a desired range of the black body curve. In addition, the controller provides selectable adjustments for values of the spectral characteristics, While maintaining substantially constant overall output intensity for the light output of White LEDs, thereby achieving Maximum Utilization.

US 9,133,990 B2 discloses an LED array includes three or more strings of bare LEDs mounted in close proximity to each other on a substrate. The strings of LEDs emit light of one or more wavelengths of blue, indigo and/or violet light, with peak wavelengths that are less than 490 mn. Luminescent materials deposited on each of the LED chips in the array emit light of different wavelength ranges that are of longer wavelengths than and in response to light emissions from the LED chips. A control circuit applies currents to the strings of LEDs, causing the LEDs in the strings to emit light, which causes the luminescent materials to emit light. A user interface enables users to control the currents applied by the control circuit to the strings of LEDs to achieve a Correlated Color Temperature (CCT) value and hue that are desired by users, With CIE chromaticity coordinates that lie on, or near to the black body radiation curve. Preferably a transparent material is dispensed on the substrate between the LED semiconductor ‘chips to substantially surround the semiconductor chips. Thereafter at least one layer containing luminescent materials is applied on the LED semiconductor chips and the transparent material.

US 2015/0289327 A1 discloses a lighting system. In one example, the lighting system comprises a circuit board including plural light emitting sets, each of the light emitting sets including one or more light emitting diodes, plural integrated circuits configured to receive a rectified sine waveform of a power source, and a dimmer circuit electrically coupled to the integrated circuits and configured to transmit a dimming signal to the integrated circuits. Each one of the integrated circuits is electrically coupled to a respective one of the light emitting sets. Each of the integrated circuits is configured to modify the rectified sine waveform into a truncated rectified sine waveform based on the dimming signal. Each of the integrated circuits is configured to turn on or off a number of the light emitting diodes included in a respective one of the light emitting sets based on the truncated rectified sine waveform.

WO 2005/009085 A1 discloses an illumination system enabling dynamic colour control of the illumination produced by the system. The illumination system comprises a plurality of light-emitting elements which create illumination at a number of different wavelengths wherein the colour that can be produced by the illumination system is based on the colour gamut defined by the colours of the individual lightemitting elements being blended. The system further includes at least one detecting device in order to collect information relating to the illumination being created by the plurality of light-emitting elements, wherein this information can relate to the luminous flux being produced at the various wavelengths. A computing system is integrated into the illumination system, wherein this computing system provides a means for receiving the information from the at least one detecting device and determines control parameters based on a multivariate function having a solution defining the hyperplane representing constant luminous intensity and chroma. Under these conditions the computing system can essentially linearise the information from the detecting device, thereby determining a number of control parameters from the input information, for transmission to a controller. The controller integrated into the system subsequently determines the control signals to be sent to the light-emitting elements in order to control the illumination produced thereby. In this manner, the illumination system according to the present invention can detect the produced illumination and dynamically alter the produced colour or intensity, for example, based on the collected information and the desired illumination result.

EP1 462 711 A1 discloses A currently-available white LED can be modified to freely set a colour temperature as well as to improve a colour rendering property. A correction-colour LED or LEDs having a peak wavelength in a specific wavelength region in association with a white LED are provided to make a colour temperature- regulable LED which permit the correction of not only a colour temperature but also a colour rendering property by means of colour-mixture of the correction-colour LED and the white LED considering the colour temperature and a spectrum distribution of the white LED. The colour temperature-regulable LED is especially useful as an shadowless operating light, a living room light and a decorative light.

None of the disclosures addressing the disadvantage that the light radiate spectrum is not very stable, and where the radiated spectrum is some white colour, and a low efficiency in producing some white colour.

SUMMARY OF THE INVENTION

An object of the invention is to overcome one or more of the disadvantages mentioned above.

According to a first aspect of the invention, a light device configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating blackbody; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the light device comprises: at least three LEDs each having distinct radiation patterns together forming the mimicked black-body radiation, wherein the at least three radiation patterns define a convex polygon surrounding a locus curve section of the locus curve defined by the body temperature range; a controller (110) configured for: receiving an input associable with a set body temperature; translating the input to a LED setting for each of the at least three LEDs; and setting the at least three LEDs according to the LED settings; and wherein the convex polygon snugly fits around the locus curve section.

Many applications require close control over the radiated light. Stability over time is of concern in many applications. Furthermore, while changing the radiated light, one or more other measurable parameters of the radiated light should preferably remain as stable as possible. In an embodiment, the LED may be a nano-dot.

Multiple LEDs may together mimic white light or light close to white light. Typically, the combination of LEDs attempts to mimic or comes close to the radiation pattern of a black-body at a particular body temperature. A shift in body temperature causes a change in the black-body radiation. It is an insight of the inventor that the locus or combined maximum of the radiation pattern of the at least three LEDs is the dominant or most important parameter. Furthermore, it is an insight of the inventor that the locus or combined maximum of the radiation pattern is dominant or most important parameter for the perception of the human, specifically the human eye and/or skin.

The controller is arranged for translating or converting a body temperature to a setting for each individual LED such that the combination of LEDs mimic the radiation pattern, more specifically the locus of a radiation pattern, of a black-body. The controller typically also receives an intensity setting. The intensity setting may be taken into account when performing the translation. The intensity setting together with the body temperature may determine the LED settings. In detail, the body temperature may determine the relation between LED settings, while the intensity setting may determine the total of the LED settings or the average of the LED settings.

The locus curve in the CIE 1931 x,y space for black-body radiation is known. The locus curve defines the locus of the black-body radiation for a body temperature from 0 Kelvin to infinity. Typically, not the complete range of locus curve is of interest or present in the product. Only a section of the locus curve is typically of interest.

The at least three LEDs each have a distinct radiation pattern. The radiation pattern may be a combination of wavelengths radiated by the LED. The radiation pattern may be seen as represented, condensed or summarized in one specific point in the CIE 1931 x,y space. Alternatively, the radiation pattern may be seen as represented, condensed or summarized in a specific, typically small area in the CIE 1931 x,y space. The small area may have different shapes, such as a circle or oval. Furthermore, the small area typically has a gradual or blurred edge. Typically, the locus of the radiation pattern of the LED in the CIE 1931 x,y space may be taken as representing the LED radiation pattern. The LED radiation pattern may alternatively be expressed in an x,y graph with on the horizontal axis the wavelength in e.g. nanometres, and on the vertical axis the intensity in e.g. Candela. The radiation patterns of the at least three are combined in the light device. The radiation patterns of the at least three are radiated together by the light device for forming a combined radiation pattern. The combined radiation pattern may be combined by averaging the three locus points of the radiation patterns for example in the CIE 1931 x,y space. This averaging may be a weighted averaging or other more advanced methods for combining these radiation patterns. The light device is configured such that the locus or combined maximum of the combined radiation pattern mimics the locus of the radiation pattern of a black-body at a particular body temperature. Alternatively, the light device is configured such that the combined radiation pattern mimics the radiation pattern of a black-body at a particular body temperature.

The radiation patterns of the at least three LEDs form a convex polygon. A convex polygon comprises a convex set. In a convex polygon, all interior angles are less than or equal to 180 degrees, while in a strictly convex polygon all interior angles are strictly less than 180 degrees. In a specific embodiment, the radiation patterns of the at least three LEDs define a strictly convex polygon.

Instead of the current selection of LEDs, it is an insight of the inventor to select LEDs with a radiation pattern close to the locus curve section. Selecting LEDs with a radiation pattern close to the curve section increases efficiency as the radiation patterns of the LEDs are closer to the selected or set point on the locus curve section. The selected or set point is determined by the body temperature. Arranging the radiation patterns of the at least three LEDs close to the locus curve section causes the combined maximum or locus of the combined radiation patterns to mimic the blackbody radiation more perfectly. Furthermore, arranging the radiation patterns of the at least three LEDs close to the locus curve section causes the combined maximum or locus of the combined radiation patterns to change less when the LED settings are changed. Thus, arranging the radiation patterns of the at least three LEDs close to the locus curve section improves stability of the combined radiation pattern in the CIE 1931 x,y space.

According to another aspect of the invention a method for producing a light device configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the method comprises the steps of: providing a controller; providing at least three groups of LEDs each group having distinct radiation patterns together forming the mimicked black-body radiation; selecting one LED from each of the at least three groups of LEDs; determining the position in the CIE 1931 x,y space of the selected LEDs based on its radiation pattern; and if the selected LEDs defining a convex polygon surrounding, preferably snugly fitting around, a locus curve section of the locus curve defined by the body temperature range, forming the light device based on the selected LEDs and the controller. The method provides the same advantages as mentioned for the light device.

According to another aspect of the invention a method for producing sets of LEDs for a light device configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the method comprises the steps of: providing at least three groups of LEDs; determining a spread in and an average of radiation patterns of LEDs of each of the group of LEDs; verifying if the average and the spread of the radiation patterns for each of the groups of LEDs defining a worst case convex polygon surrounds a locus curve section of the locus curve defined by the body temperature range; if the verification is negative, adjusting at least one of the average and the spread of the radiation patterns of the at least one of the at least three groups of LEDs; and if the verification is positive, selecting a LED from each of the three groups for forming a set of LEDs for a light device for together forming the mimicked black-body radiation. The method provides the same advantages as mentioned for the light device.

According to another aspect of the invention a data processing system comprising means for carrying out the steps of any of the embodiments of the methods or the steps of the controller of any of the embodiments of the light device. The data processing system provides the same advantages as mentioned for the light device.

According to another aspect of the invention a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of any of the embodiments of the methods or the steps of the controller of any of the embodiments of the light device. The computer-readable storage medium provides the same advantages as mentioned for the light device.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In an embodiment of the light device, the distance between the convex polygon and the locus curve section in the CIE 1931 x,y space is at least 0.01 , preferably 0.03, more preferably 0.04, most preferably 0.05. Production may cause variations. Furthermore, the radiation pattern of a LED may vary over its lifetime, such as its economic and/or technical lifetime. Snugly fitting should be interpreted as providing enough distance between the convex polygon and the locus curve section for advantageously anticipating one or more of the mentioned variations.

In an embodiment of the light device, the distance between the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.15, preferably 0.12, more preferably 0.10, most preferably 0.08. Production may cause variations. Furthermore, the radiation pattern of a LED may vary over its lifetime, such as its economic and/or technical lifetime. While these variations may influence snugly fitting, on the other hand arranging the radiation patterns close, such as snugly, to the locus curve section provides the advantages of improved stability. Another advantage of the invention in general may be that if the radiation patterns of the LEDs are close to the locus curve section, the LEDs mimic the black-body radiation more efficiently. The efficiency is found in that the LEDs mimic the black-body radiation more closely thereby less of the radiated spectrum from one of the LEDs is to be ignored or filtered out or compensated for by the other LEDs. Snugly fitting should be interpreted as providing only enough distance between the convex polygon and the locus curve section for advantageously anticipating one or more of the mentioned variations while still providing the advantages as defined for this invention.

In an embodiment of the light device, the locus is a Planckian locus or black body locus hereby advantageously detailing the locus. In an embodiment of the light device, at least one of the LED settings is a voltage and/or a current driving the associated LED. Alternatively, at least one of the LED settings is associated or associable with a voltage and/or a current driving the associated LED. In an embodiment of the light device, the locus curve section is advantageously in the visible light spectrum, preferably ranges from yellow to blue, more preferably ranges from yellow-white to white, most preferably substantially white. In an embodiment of the light device, the locus curve section advantageously represents a body temperature in the range of 2,000K to °°, preferably 2,500K to 100,000K, more preferably 3,000K to 20,000K, more preferably 4,000K to 10,000K, most preferably 4,500K to 9,000K.

In an embodiment of the light device, each of the radiation patterns of the at least three LEDs has a predictable shift in the CIE 1931 x,y space over its operational lifetime; and the convex polygon snugly fits around the locus curve section during the operational lifetime. This embodiment provides a balance between on one side arranging the convex polygon close to the locus curve section for stability and/or efficiency, while on the other side the variation of the radiated spectrum can be accommodated. In a further embodiment of the light device, the predictable shift is predicted based on a trained neural network. The variation in production of the radiated patterns or spectra as well as the variation of the radiated patterns or spectra over its lifetime, or even in combination, are typically highly non-linear, non-symmetric, depending on environmental conditions, such as environmental temperature, humidity, rain or exposure to sunlight, or combinations. Predicting the change of radiated spectrum is therefore advantageously predicted by a trained neural network. The neural network may be trained with samples from production of the different LEDs. The trained neural network may be provided with samples from production of the different LEDs for providing a more accurate prediction. The trained neural network may be provided with measurements from light devices in the field for providing a prediction for that light device. In a further preferred embodiment of the light device, the trained neural network is trained with data from testing a sample set of LEDs; and the sample set of LEDs statistically represents at least one of the at least three LEDs defining the convex polygon. In a further preferred embodiment, testing simulates typical operational use. In a further preferred embodiment, three sample sets of LEDs statistically represents the at least three LEDs, respectively.

In an embodiment of the light device, the light device comprises at least four LEDs, preferably five LEDs, more preferably six LEDs, all having distinct radiation patterns forming the convex polygon for more snugly fitting around the locus curve section. With more distinct radiation patterns the black-body radiation may be mimicked more precise. Furthermore, with more distinct radiation patterns the convex polygon may even more snugly fit around the locus curve section.

In an embodiment of the light device the convex polygon is formed such that if one of the LEDs fails or the radiation pattern of one of the LEDs shifts too much, and this radiation pattern is removed from the convex polygon thereby forming a reduced convex polygon, then this reduced convex polygon snugly fits around a reduced locus curve section; wherein the reduced locus curve section is substantially equal to the locus curve section. This increases dependability during operation and/or lifetime of the light device for failure of one of the LEDs.

In an embodiment of the light device the convex polygon is formed such that if a predefined or specific one of the LEDs fails or the radiation pattern of a predefined or specific one of the LEDs shifts too much, and this LED is removed from the convex polygon thereby forming a reduced convex polygon, then this reduced convex polygon snugly fits around a reduced locus curve section; wherein the reduced locus curve section is substantially equal to the locus curve section. A LED with a specific and/or distinct radiation pattern may statistically fail more often compared to others. This increases dependability during operation and/or lifetime of the light device for failure of a predefined or specific one of the LEDs.

In an embodiment the light device comprises a support LED having a radiation pattern distinct from the radiation patterns forming the convex polygon; wherein the support LED has a radiation pattern within the convex polygon; and wherein the controller is also configured for: translating the input to a support LED setting; and setting the support LED according to the support LED setting for contributing to the mimicked black-body radiation. The radiation pattern of the support LED is typically arranged on or close to the locus curve section. The support LED enhances efficiency of the light device mimicking black-body radiation. The support LED enhances how well the light device mimics the black-body radiation. The support LED causes other LEDs forming the convex polygon to radiate less thereby increasing their operational lifetime.

In an embodiment of the method for producing a light device, the step of determining comprises the step of determining the position in the CIE 1931 x,y space of the selected LEDs over its operational lifetime; the condition for the forming step is extended with the selected LEDs defining a convex polygon surrounding, preferably snugly fitting around, a locus curve section of the locus curve defined by the body temperature range over its lifetime. This embodiment provides a balance between on one side arranging the convex polygon close to the locus curve section for stability and/or efficiency, while on the other side the variation of the radiated spectrum can be accommodated. In a further embodiment of the method, the predictable shift is predicted based on a trained neural network. The variation in production of the radiated patterns or spectra as well as the variation of the radiated patterns or spectra over its lifetime, or even in combination, are typically highly non-linear, non-symmetric, depending on environmental conditions, such as environmental temperature, humidity, rain or exposure to sunlight, or combinations. Predicting the change of radiated spectrum is therefore advantageously predicted by a trained neural network. The neural network may be trained with samples from production of the different LEDs. The trained neural network may be provided with samples from production of the different LEDs for providing a more accurate prediction. The trained neural network may be provided with measurements from light devices, preferably formed according to the method, in the field for providing a prediction for that light device. In a further preferred embodiment of the method, the trained neural network is trained with data from testing a sample set of LEDs; and the sample set of LEDs statistically represents at least one of the at least three LEDs defining the convex polygon. In a further preferred embodiment, testing simulates typical operational use. In a further preferred embodiment, three sample sets of LEDs statistically represents the at least three LEDs, respectively. In a further embodiment, the method for producing a light device comprises the step of providing a trained neural network for predicting the shift of the radiation pattern over its lifetime; and the step of determining the position over its lifetime is based on the results from the trained neural network.

In a further embodiment, the method for producing a light device comprises the steps of: sampling a set of LEDs statistically representing at least one of the at least three groups of LEDs; testing a sample set of LEDs for generating test data representing change of radiation pattern preferably testing simulates typical operational use; and training the neural network with the test data. This advantageously provides a trained neural network based on representative data.

In an embodiment, the method comprises the steps of: providing a controller; and forming the light device based on the selected LEDs and the controller. This advantageously provides a tested and/or for the operational and/or technical lifetime statistically guaranteed light device of which the convex polygon snugly fits around the locus curve section.

In an embodiment, the method comprises the step of adjusting comprises the steps of: selecting LEDs from the at least three groups of LEDs for forming a new group of LEDs; wherein selecting is based on the determined spread in and the determined average of the radiation patterns; and wherein in the verifying step the new group of LEDs is used. This advantageously provides a tested and/or for the operational and/or technical lifetime statistically guaranteed light device of which the convex polygon snugly fits around the locus curve section.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

Figure 1 schematically shows a CIE 1931 x,y space with the locus curve; Figure 2 schematically shows the black-body radiation locus curve;

Figure 3 schematically shows the black-body radiation locus curve with a first convex polygon;

Figure 4 schematically shows the black-body radiation locus curve with a second convex polygon;

Figure 5 schematically shows the black-body radiation locus curve with a third convex polygon;

Figure 6 schematically shows a light device;

Figure 7 schematically shows a method for producing a light device;

Figure 8 schematically shows a method for producing sets of LEDs for a light device; and

Figure 9 schematically shows an embodiment of a computer program product, computer readable medium and/or non-transitory computer readable storage medium according to the invention.

The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals. LIST OF REFERENCE NUMERALS

DETAILED DESCRIPTION OF THE FIGURES

The following figures may detail different embodiments. Embodiments can be combined to reach an enhanced or improved technical effect. These combined embodiments may be mentioned explicitly throughout the text, may be hint upon in the text or may be implicit.

Figure 1 schematically shows a CIE 1931 x,y space 10. The CIE 1931 x,y space is a colour space. The edges of the colour space are defined by a flat side and an edge extending as a lobe from this flat side. The left bottom corner has a blue colour. The right bottom has a red colour. The top of the lobe has a green colour. The area between these extremes comprises colour gradients for gradually changing colour when traversing the colour space. On the edge of the lobe the wavelength of the particular colour at that point on the edge of the lobe is indicated. The source for this CIE 1931 x,y space is the Wikipedia page for the Planckian locus.

Figure 1 further comprises the locus curve 20 for black-body radiation. The actual locus of the black-body radiation shifts over this curve depending on the body temperature. Several body temperatures are indicated ranging from 1500 to °° or infinity.

Figure 2 schematically shows the black-body radiation locus curve 20 from Figure 1 without the CIE 1931 x,y space. Although the body temperatures are shown, these temperatures are removed for clarity reasons in the Figures 3-5.

Figure 3 schematically shows the black-body radiation locus curve 20 with a first convex polygon 150. The first convex polygon is a triangle. The first convex polygon comprises a first vertex 141 , a second vertex 142, and a third vertex 143. The first vertex represents the locus of the radiation pattern of a first LED. The second vertex represents the locus of the radiation pattern of the second LED. The third vertex represents the locus of the radiation pattern of the third LED. The vertex may be a point in the CIE 1931 x,y space. Alternatively, the vertex may be an area, preferably a small area in the CIE 1931 x,y space. The first convex polygon further comprises a first side 151 arranged between the first and second vertices, a second side 152 arranged between the second and third vertices, and a third side 153 arranged between the third and first vertices. The part of the locus curve covered by the area of the convex polygon is labelled locus curve section.

Each of the LEDs radiates a distinct radiation pattern represented as a vertex of the convex polygon in the CIE 1931 x,y space. Depending on the LED setting of a particular LED, this particular LED may radiate more or less compared to the other LEDs of the light device. The convex polygon defines a control area. Depending on the different LED settings for the LEDs the combined radiation pattern of the LEDs, preferably the locus of the combined radiation pattern of the LED, may be represented as a point or small area in the CIE 1931 x,y space, which point or small area is arranged on the control area. Typically, the more a LED is powered the more dominant its radiation pattern is in the combined radiation pattern, the more the combined radiation pattern is close to the radiation pattern of this LED in the CIE 1931 x,y space.

Figure 4 schematically shows the black-body radiation locus curve with a second convex polygon. The same numbers as mentioned in Figure 3 have the same meaning in Figure 4. The second convex polygon is a quadrilateral which is convex. The second convex polygon further comprises a fourth vertex 144. The fourth vertex represents the locus of the radiation pattern of a fourth LED. Different from Figure 3, the third side is arranged between the third vertex and the fourth vertex. The second convex polygon further comprises a fourth side 154 arranged between the fourth and first vertices.

Figure 5 schematically shows the black-body radiation locus curve with a third convex polygon. The same numbers as mentioned in Figures 3 and 4 have the same meaning in Figure 5. The third convex polygon is a pentagon which is convex. The third convex polygon further comprises a fifth vertex 145. The fifth vertex represents the locus of the radiation pattern of a fifth LED. Different from Figure 4, the fourth side is arranged between the fourth vertex and the fifth vertex. The third convex polygon further comprises a fifth side 155 arranged between the fifth and first vertices.

Figure 5 further shows a support LED 160. The support LED may be used to support the combined radiation pattern such that when the support LED radiates, the combined radiated pattern, preferably the locus of the combined radiated pattern, is closer to the locus of the support LED in the CIE 1931 x,y space. The support radiation pattern, preferably the locus of the support radiation pattern, is arranged on the area of the convex polygon.

An effect may be that the third LED in this case may radiate less for moving the combined radiated pattern, preferably the locus of the combined radiated pattern, closer to the locus of the third LED in the CIE 1931 x,y space, especially when the combined radiated pattern is far away from the third vertex. Another effect may be that the combined radiated pattern, preferably the locus of the combined radiated pattern, in the CIE 1931 x,y space may be controlled with higher accuracy and/or stability.

Furthermore, when the third LED fails, the convex polygon is reduced to the reduced convex polygon comprising a first side 151 , a first alternative side 161 , a second alternative side 162, a fourth side 154, and a fifth side 155. The reduced polygon still allows to cover a considerable part of the locus curve, labelled reduced locus curve section. Although the reduced locus curve section is smaller compared to the locus curve section, the reduced locus curve section still allows the light device to radiate light with a locus in the CIE 1931 x,y space covered by the reduced convex polygon. The effect is that the support LED increases the reliability of the light device. A further effect is that the combined radiation pattern can be controlled with higher accuracy.

Figure 6 schematically shows a light device 100. The light device comprises a controller 110, and at least three LEDs 120, 121 , 122, 123. The controller controls the LEDs by communicating a LED setting 130, 131 , 132, 133 to the respective LEDs.

The controller is configured for receiving an input associable with a set body temperature; translating the input to a LED setting for each of the at least three LEDs; and setting the at least three LEDs according to the LED settings.

Figure 7 schematically shows a method 200 for producing a light device. The method comprises the step of providing 210 a controller. The method further comprises the step of providing 220 at least three groups of LEDs each having distinct radiation patterns together forming the mimicked black-body radiation. The method further comprises the step of selecting 230 one LED from each of the at least three groups of LEDs. The method further comprises the step of determining 240 the position in the CIE 1931 x,y space of the selected LEDs based on its radiation pattern. The method further comprises the step of if the selected LEDs defining a convex polygon surrounding, preferably snugly fitting around, a locus curve section of the locus curve defined by the body temperature range, forming 250 the light device based on the selected LEDs and the controller.

Figure 8 schematically shows a method 300 for producing sets of LEDs for a light device. The method comprises the step of providing 310 at least three groups of LEDs. The method further comprises the step of determining 320 a spread in and an average of radiation patterns of LEDs of each of the group of LEDs. The method further comprises the step of verifying 330 if the average and the spread of the radiation patterns for each of the groups of LEDs defining a worst-case convex polygon surrounds a locus curve section of the locus curve defined by the body temperature range. The method further comprises the step of if the verification is negative, adjusting 340 at least one of the average and the spread of the radiation patterns of the at least one of the at least three groups of LEDs. The method further comprises the step of if the verification is positive, selecting 350 a LED from each of the three groups for forming a set of LEDs for a light device.

Figure 9 schematically shows an embodiment of a computer program product 1000, computer readable medium 1010 and/or non-transitory computer readable storage medium according to the invention comprising computer readable code 1020.

It will also be clear that the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. These embodiments are within the scope of protection and the essence of this invention and are obvious combinations of prior art techniques and the disclosure of this patent. Devices functionally forming separate devices may be integrated in a single physical device.

The term “substantially” herein, such as in “substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

The term "functionally" will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in “functionally parallel”, a skilled person will understand that the adjective “functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective “functionally” was not present. The term “functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word “substantially” explained above. For instance, “functionally parallel” relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.

The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and “to include”, and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device or apparatus claims enumerating several means, several of these means may be embodied by one and the same item of hardware.

The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

It will be appreciated that the invention also applies to computer programs, particularly computer programs on or in a carrier, adapted to put the invention into practice. The program may be in the form of a source code, a code intermediate source and an object code such as in a partially compiled form, or in any other form suitable for use in the implementation of the method according to the invention. It will also be appreciated that such a program may have many different architectural designs. For example, a program code implementing the functionality of the method or system according to the invention may be sub-divided into one or more sub-routines. Many different ways of distributing the functionality among these sub-routines will be apparent to the skilled person. The sub-routines may be stored together in one executable file to form a self-contained program. Such an executable file may comprise computer-executable instructions, for example, processor instructions and/or interpreter instructions (e.g. Java interpreter instructions). Alternatively, one or more or all of the sub-routines may be stored in at least one external library file and linked with a main program either statically or dynamically, e.g. at run-time. The main program contains at least one call to at least one of the sub-routines. The sub-routines may also comprise function calls to each other. An embodiment relating to a computer program product comprises computer-executable instructions corresponding to each processing stage of at least one of the methods set forth herein. These instructions may be sub- divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically. Another embodiment relating to a computer program product comprises computer-executable instructions corresponding to each means of at least one of the systems and/or products set forth herein. These instructions may be sub- divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically.

The carrier of a computer program may be any entity or device capable of carrying the program. For example, the carrier may include a data storage, such as a ROM, for example, a CD ROM or a semiconductor ROM, or a magnetic recording medium, for example, a hard disk. Furthermore, the carrier may be a transmissible carrier such as an electric or optical signal, which may be conveyed via electric or optical cable or by radio or other means. When the program is embodied in such a signal, the carrier may be constituted by such a cable or other device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted to perform, or used in the performance of, the relevant method.

The various aspects discussed in this patent can be combined in order to provide additional advantages.

Claims

1 . Light device (100) configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve (20) in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the light device comprises:

- at least three LEDs (120, 121 , 122, 123) each having distinct radiation patterns (141 , 142, 143, 144, 145) together forming the mimicked black-body radiation, wherein the at least three radiation patterns define a convex polygon (150, 150’, 150”) surrounding a locus curve section of the locus curve defined by the body temperature range;

- a controller (110) configured for: receiving an input associable with a set body temperature; translating the input to a LED setting (130, 131 , 132, 133) for each of the at least three LEDs; and setting the at least three LEDs according to the LED settings; wherein each of the radiation patterns of the at least three LEDs has a predictable shift in the CIE 1931 x,y space over its operational lifetime; and wherein the convex polygon snugly fits around the locus curve section during the operational lifetime.

2. Light device according to the preceding claim, wherein the distance between the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.15, preferably 0.12, more preferably 0.10, most preferably 0.08.

3. Light device according to any of the preceding claims, wherein the convex polygon comprises line segments; and wherein the distance between line segments of the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.05, preferably 0.04, more preferably 0.0.03, most preferably 0.02.

4. Light device according to any of the preceding claims, wherein the convex polygon comprises corners; and wherein the distance between the corners of the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.15, preferably 0.12, more preferably 0.10, most preferably 0.08.

5. Light device according to any of the preceding claims, wherein the predictable shift is based on a provided LED model.

6. Light device according to any of the preceding claims, wherein the provided model LED model is provided for each of the at least three LEDs.

7. Light device according to any of the preceding claims, wherein the light device comprises a trained neural network; and wherein the predictable shift, preferably when depending on claim 5 the predictable shift of the provide LED model, is predicted based on the trained neural network.

8. Light device according to the preceding claim, wherein the trained neural network is trained with data from testing a sample set of LEDs; wherein the sample set of LEDs statistically represents at least one of the at least three LEDs defining the convex polygon; wherein preferably testing simulates typical operational use; and wherein preferably three sample sets of LEDs statistically represent the at least three LEDs, respectively.

9. Light device according to the preceding claim, wherein the distance between the convex polygon and the locus curve section in the CIE 1931 x,y space is at least 0.01 , preferably 0.03, more preferably 0.04, most preferably 0.05.

10. Light device according to any of the preceding claims, wherein the locus is a Planckian locus or black body locus.

11 . Light device according to any of the preceding claims, wherein at least one of the LED settings is a voltage and/or a current driving the associated LED.

12. Light device according to any of the preceding claims, wherein the locus curve section is in the visible light spectrum, preferably ranges from yellow to blue, more preferably ranges from yellow-white to white, most preferably substantially white.

13. Light device according to any of the preceding claims, wherein the locus curve section represents a body temperature in the range of 2,000K to °°, preferably 2,500K to 100,000K, more preferably 3,000K to 20,000K, more preferably 4,000K to 10,000K, most preferably 4,500K to 9,000K.

14. Light device according to any of the preceding claims, wherein the light device comprises at least four LEDs, preferably five LEDs, more preferably six LEDs, all having distinct radiation patterns forming the convex polygon for more snugly fitting around the locus curve section.

15. Light device according to any of the preceding claims, comprising a support LED having a radiation pattern distinct from the radiation patterns forming the convex polygon; wherein the support LED has a radiation pattern within the convex polygon; and wherein the controller is also configured for: translating the input to a support LED setting; and setting the support LED according to the support LED setting for contributing to the mimicked black-body radiation.

16. Method for producing a light device configured for radiating mimicked blackbody radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the method comprises the steps of: - providing a controller;

- providing at least three groups of LEDs each group having distinct radiation patterns together forming the mimicked black-body radiation;

- selecting one LED from each of the at least three groups of LEDs;

- determining a position in the CIE 1931 x,y space of the selected LEDs over its operational lifetime based on its radiation pattern and a predicted shift in the CIE 1931 x,y space over its operational lifetime; and

- if the selected LEDs defining a convex polygon snugly fitting around a locus curve section of the locus curve defined by the body temperature range over its lifetime, forming the light device based on the selected LEDs and the controller.

17. Method for producing a light device according to the preceding claim, wherein the distance between the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.15, preferably 0.12, more preferably 0.10, most preferably 0.08.

18. Method for producing a light device according to any of the preceding claims 16-

17, wherein the convex polygon comprises line segments; and wherein the distance between line segments of the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.05, preferably 0.04, more preferably 0.0.03, most preferably 0.02.

19. Method for producing a light device according to any of the preceding claims 16-

18, wherein the convex polygon comprises corners; and wherein the distance between the corners of the convex polygon and the locus curve section in the CIE 1931 x,y space is at most 0.15, preferably 0.12, more preferably 0.10, most preferably 0.08.

20. Method for producing a light device according to any of the preceding claims 16-

19, wherein the method comprises the step of receiving a LED model; and wherein the predictable shift is based on a provided LED model.

21 . Method for producing a light device according to any of the preceding claims 16-

20, wherein the step of receiving a model LED model comprises receiving a LED model for each of the at least three LEDs.

22. Method for producing a light device according to any of the preceding claims 16- 21 , comprising the step of providing a trained neural network for predicting the shift of the radiation pattern over its lifetime; and wherein the step of determining the position over its lifetime is based on the results from the trained neural network.

23. Method for producing a light device according to the preceding claim, comprising the steps of:

- sampling a set of LEDs statistically representing at least one of the at least three groups of LEDs;

- testing a sample set of LEDs for generating test data representing change of radiation pattern preferably testing simulates typical operational use; and

- training the neural network with the test data.

24. Method for producing sets of LEDs for a light device configured for radiating mimicked black-body radiation; wherein black-body radiation has a locus curve in the CIE 1931 x,y space depending on a body temperature of a radiating black-body; wherein the mimicked black-body radiation mimics black-body radiation for a body temperature range; and wherein the method comprises the steps of:

- providing at least three groups of LEDs;

- determining a spread in and an average of radiation patterns of LEDs of each of the group of LEDs;

- verifying if the average and the spread of the radiation patterns over its operational lifetime based on its radiation pattern and a predicted shift in the CIE 1931 x,y space over its operational lifetime for each of the groups of LEDs defining a convex polygon surrounds a locus curve section of the locus curve defined by the body temperature range; - if the verification is negative, adjusting at least one of the average and the spread of the radiation patterns of the at least one of the at least three groups of LEDs; and

- if the verification is positive, selecting a LED from each of the three groups for forming a set of LEDs for a light device for together forming the mimicked black-body radiation.

25. Method according to the preceding claim comprising the steps of:

- providing a controller; and - forming the light device based on the selected LEDs and the controller.

26. Data processing system comprising means for carrying out the steps of any of the claims 16-25.

27. Computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of any of the claims 16-25.