Method for generating light spectra and corresponding device

1. A method for generating a target light starting from a plurality of light sources, each having an individual emission spectrum, comprising the steps of:

selecting a target colour from a target region of a colour space; and

emitting a target light from said light sources according to a weighted combination of light sources corresponding to said target colour;

for said target colour, said weighted combination is obtained from an output model which is optimized according to an optimization parameter, and wherein said output model is previously determined in a modelling stage comprising the following steps:

calculating a plurality of mixed spectra, each being a weighted combination of said individual emission spectra of said plurality of light sources;

for each mixed spectrum of said plurality of mixed spectra, calculating colour coordinates and an optimization parameter of said mixed spectrum;

partitioning in sectors a modelling region of said colour space;

for each sector, selecting an optimized mixed spectrum as the mixed spectrum contained in said sector having the best optimization parameter; thus obtaining an optimized weighted combination for said colour sector, as the weighted combination of said optimized mixed spectrum;

using the optimized weighted combination of each of said sectors, establishing a correspondence between colour coordinates and weighted combinations;

thus obtaining said output model ( 3 ).

2. The method according to claim 1 , where said colour space has perceptual uniformity.

3. The method according to claim 1 , where said optimization parameter comprises at least one of the following:

Colour Fidelity;

Colour Gamut;

Circadian Factor;

Luminous Efficacy of Radiation, LER; and

Energy Efficiency;

or a combination thereof.

4. The method according to claim 1 , where said output model comprises:

a look-up table relating ranges of colour coordinates with a corresponding weighted combination; or

a plurality of individual look-up tables, one for each light source of said plurality of light sources, and each relating ranges of colour coordinates with a corresponding weight of the light source that corresponds to said individual look-up table.

5. The method according to claim 1 , where said output model comprises:

a mathematical function having as an input colour coordinates and having as an output a corresponding weighted combination; or

a plurality of independent mathematical functions, one for each light source of said plurality of light sources, and each having as an input colour coordinates and having as an output a corresponding weight of said light source.

6. The method according to claim 1 , where said plurality of light sources comprise LEDs of different types.

7. A device for generating target lights having:

a power source;

a plurality of light sources, each having at least one light radiating element;

a control module having storage means; and

powering means for said plurality of light sources, said powering means being controlled by said control module;

said control module being configured to:

selecting a target colour from a target region of a colour space; and

controlling said powering means for driving said plurality of light sources to emit a target light according to a weighted combination of light sources;

said control module is further configured to, for said target colour, obtaining said weighted combination from an output model which is optimized according to an optimization parameter, and wherein said output model is previously determined in the modelling stage of the method according to claim 1 .

8. The device according to claim 7 , where said plurality of light sources comprise LEDs of different types.

9. The device according to claim 7 , where said power source comprises

an AC/DC converter with a first output voltage; and

a DC/DC converter, connected to said first output voltage and having a second output voltage, lower than said first output voltage;

wherein said first output voltage is connected to said powering means in order to power said plurality of light sources, and wherein said second output voltage is connected to said control module.

10. The device according to claim 7 , further comprising a source of time information, and wherein selecting a target colour comprises selecting a target colour depending a time information provided by said source of time information.

11. The device according to claim 7 , further comprising a sensor module, connected to said control module, and comprising at least one sensor configured to provide environmental information to said control module, and wherein selecting a target colour to be generated comprises selecting a target colour depending on said environmental information.

12. The device according to claim 7 , where said target light has an emission colour from a plurality of emission colours, said optimization parameter is a Colour Fidelity parameter and wherein at least a 50% of those emission colours of said plurality of emission colours that are located within said target region fulfil a quality criterion, said quality criterion comprising a Colour Fidelity parameter;

said target region being defined by the area contained in any of a first ellipse and a second ellipse, both ellipses described by the general formula:

(

(

x

-

h

)

⁢

cos

⁡

(

A

)

+

(

y

-

k

)

⁢

sin

⁡

(

A

)

)

2

a

2

+

(

(

x

-

h

)

⁢

sin

⁡

(

A

)

-

(

y

-

k

)

⁢

cos

⁡

(

A

)

)

2

b

2

=

1

wherein x corresponds to CCT, measured in Kelvin (K); and y corresponds to Duv;

wherein, for said first ellipse:

h=3650

k=−0.0025

A=8.737×10 −6 in radians

a=900

b=0.012

and for said second ellipse:

h=5050

k=0.0045

A=1.745×10 −6 in radians

a=550

b=0.0032.

13. The device according to claim 12 , where said quality criterion comprises an IES TM-30-15 Rf parameter with a value of at least 50; and wherein the perimeter of said target region is defined in a Duv-CCT diagram by straight lines, each successively connecting the following points:

P1: CCT=1411K, Duv=−0.0114;

P2: CCT=5869K, Duv=0.06;

P3: CCT=10000K, Duv=0.06;

P4: CCT=10000K, Duv=−0.0265;

P5: CCT=2576K, Duv=−0.0507; and

P6: CCT=1411K, Duv=−0.0114.

14. The device according to claim 12 , where said quality criterion comprises an IES TM-30-15 Rf parameter with a value of at least 70; and wherein the perimeter of said target region is defined in a Duv-CCT diagram by straight lines, each successively connecting the following points:

P1: CCT=1685 K, Duv=−0.0121;

P2: CCT=4046 K, Duv=0.0219;

P3: CCT=7946 K, Duv=0.0572;

P4: CCT=10000 K, Duv=0.0416;

P5: CT=10000 K, Duv=−0.0107;

P6: CCT=2797 K, Duv=−0.0353; and

P7: CCT=1685 K, Duv=−0.0121.

15. The device according to claim 12 , where said quality criterion comprises an IES TM-30-15 Rf parameter with a value of at least 90; and wherein the perimeter of said target region ( 7 ) is defined in a Duv-CCT diagram by straight lines, each successively connecting the following points:

P1: CCT=2181 K, Duv=−0.0083;

P2: CCT=2851 K, Duv=0.002;

P3: CCT=6648 K, Duv=0.0221;

P4: CCT=7557 K, Duv=0.006;

P5: CCT=7458 K, Duv=−0.0008;

P6: CCT=3095 K, Duv=−0.0184; and

P7: CCT=2181 K, Duv=−0.0083.