Camera flash with reconfigurable emission spectrum
View Patent ↗A method and an apparatus for spectrum synthesis for use in a flash unit, wherein the spectrum synthesis includes combining a plurality of emissive light sources in order to provide a combine output beam and producing the output spectrum for the combined output beam at least based on a reference spectrum. The reference spectrum can be obtained by sensing the spectrum of ambient light or selected from a plurality of stored spectra. The flash unit has at least two emissive light sources and each of the light sources can be adjusted relative to each other so that the outputs from the light sources can mimic a selected illumination scenario. It is possible to use a mixture of quantum dots to tailor each light source so that the combined spectra from different light sources can reasonably mimic a number of frequently used illumination scenario.
1. A method for producing an output spectrum of a flash unit, comprising:
combining a plurality of emissive light sources for providing a combined output beam; and
producing the output spectrum for the combined output beam, the output spectrum at least partially based on a reference spectrum, the reference spectrum selected from a plurality of stored spectra, each of the stored spectra indicative of one or more ambient illumination sources associated with one or more respective illumination scenarios.
2. The method of claim 1 , further comprising:
sensing a spectrum of ambient light for providing the reference spectrum.
3. The method of claim 1 , wherein the stored spectra are representable by a plurality of weighting values for said combining.
4. The method of claim 1 , further comprising:
sensing a spectrum of ambient light for providing a sensed spectrum; and
selecting the reference spectrum at least partly based on the sensed spectrum.
5. The method of claim 1 , wherein the plurality of emissive light sources comprise:
a first emissive light source arranged to provide a first light beam of a first spectrum; and
a second emissive light source arranged to provide a second light beam of a second spectrum, wherein at least part of the second spectrum is different from the first spectrum, and wherein at least one of the first emissive light source and the second emissive light source is adjustable for producing the output spectrum.
6. The method of claim 5 , wherein said at least one of the first emissive light source and the second emissive light source is arranged to receive a pulse-width modulated power for producing a corresponding light beam, and wherein pulse width of the modulated power is changed for adjusting said at least one of the first emissive light source and the second emissive light source.
7. A flash unit for use in a camera, comprising:
a plurality of emissive light sources for providing a combined output beam; and
a power receiver for receiving electric current to power each of the plurality of emissive light sources, wherein the electric current to power at least some of the plurality of emissive light sources is adjustable so as to produce an output spectrum for the combined output beam, the output spectrum at least partially based on a reference spectrum, the reference spectrum selected from a plurality of stored spectra, each of the spectra indicative of one or more ambient illumination sources associated with one or more respective illumination scenarios.
8. The flash unit of claim 7 , wherein the plurality of emissive light sources comprise:
a first emissive light source arranged to provide a first light beam of a first spectrum; and
a second emissive light source arranged to provide a second light beam of a second spectrum, wherein at least part of the second spectrum is different from the first spectrum, and wherein at least one of the first emissive light source and the second emissive light source is adjustable for producing the output spectrum.
9. An apparatus, comprising:
a connector for receiving a flash unit, wherein the flash unit comprises a plurality of emissive light sources arranged to receive electric current for producing a combined light output;
a processor configured to adjust the electric current so as to produce an output spectrum of the combined light output, the output spectrum at least based on a reference spectrum, the reference spectrum selected from a plurality of stored spectra, each of the stored spectra indicative of one or more ambient illumination sources associated with one or more respective illumination scenarios.
10. The apparatus of claim 9 , further comprising:
a sensor for sensing a spectrum of ambient light for providing the reference spectrum.
11. The apparatus of claim 9 , wherein the stored spectra are representable by a plurality of weighting values for producing the combined light output.
12. The apparatus of claim 9 , wherein the plurality of emissive light sources comprise:
a first emissive light source arranged to provide a first light beam of a first spectrum; and
a second emissive light source arranged to provide a second light beam of a second spectrum, wherein at least part of the second spectrum is different from the first spectrum, and wherein at least one of the first emissive light source and the second emissive light source is adjustable for producing the output spectrum.
13. The apparatus of claim 12 , wherein the electric current received by at least one of the first emissive light source and the second emissive light source is pulse-width modulated, and wherein pulse width of the modulated power is changed for adjusting said at least one of the first emissive light source and the second emissive light source.
14. The apparatus of claim 9 , comprising a camera.
15. The apparatus of claim 9 , comprising a mobile terminal.
16. The method of claim 5 , wherein at least one of the first emissive light source and the second emissive light source comprises:
one or more excitable light emission materials, and
at least one light emitting unit arranged to excite said one or more excitable light emission materials for providing at least one of the first and second light beams.
17. The method of claim 16 , further comprising:
providing a spatial light modulator for controlling light output from said one or more excitable light emission materials.
18. The apparatus of claim 12 , wherein at least one of the first emissive light source and the second emissive light source comprises:
one or more excitable light emission materials, and
at least one light emitting unit arranged to excite said one or more excitable light emission materials for providing at least one of the first and second light beams.
19. The apparatus of claim 18 , further comprising:
a spatial light modulator for controlling light output from said one or more excitable light emission materials.
20. The apparatus of claim 18 , wherein said one or more excitable light emission materials comprise one or more quantum dots and said at least one light emitting unit comprises one or more light-emitting diodes.
21. The method of claim 1 , wherein said one or more illumination sources comprise ambient illumination sources.