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US 8,125,157 B2Granted
Light source and method for producing light modifiable in colour and/or luminosity
AssigneeKoninklijke Philips Electronics N.V.
InventorCornelis Reinder Ronda
Life of this patent
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Abstract
The present invention relates to a light source, which produces light leaving the light source with modifiable color and luminosity, with at least one light emitting diode for emitting primary radiation, comprising a layer connected with said diode, wherein said layer includes at least one luminescent material for converting the primary radiation into a secondary radiation.
Claims12
A light source for producing light with modifiable colours and including
- at least one light emitting diode for emitting primary radiation,
- a layer coupled with said at least one light emitting diode and including at least one luminescent material for converting the primary radiation into a secondary radiation,
- a switching device for driving the at least one light emitting diode with a pulse-shaped current using pulse with modulation to effect production of the primary and secondary radiation in such a way that the luminosity of the light and the colour are changeable independently, wherein a pulse width of the pulse-shaped current is substantially equal to a decay time of the luminescent material and is operably modified by controlling said control device to change said luminosity and a pulse height is operably modified by controlling said switching device to modify said colour.
A light source for producing light including
- at least one light emitting diode for emitting primary radiation,
- a layer coupled with said at least one light emitting diode and including at least one luminescent material for converting the primary radiation into a secondary radiation,
- a switching device for driving the at least one light emitting diode with a pulse-shaped current comprising a pulse width (pulse period) and a distance between pulses (switching-off period), wherein
- the at least one luminescent material, which has a decay time, is excited by the primary radiation in such a way that the luminosity and the colour of the light leaving the at least one light emitting diode are changeable independently from each other, whereby the pulse width is modifiable to be substantially equal to the decay time, allowing said switching device to operably modify said luminosity and whereby said pulses are operably modified by controlling said switching device to independently change said colour relative to said luminosity.
1 more element
A light source for producing modifiable colour and light intensity, comprising:
- at least one light emitting diode for emitting primary radiation;
- a layer in optical alignment with said at least one light emitting diode and including at least one luminescent material for converting said primary radiation into a secondary radiation;
- a switching device in electrical communication with said at least one light emitting diode and operably driving said at least one light emitting diode with pulse width modulated current having an off-pulse time period between pulses;
- wherein said at least one luminescent material has a decay time and is excited by said primary radiation in such a way that the luminosity and the colour of said light leaving said light source are changeable independently from each other;
- whereby said off-pulse time period is modifiable to be equal to or greater than said decay time and is modifiable to change the luminosity of said at least one light emitting diode,
- and further whereby pulse heights are operably modified by controlling said switching device to independently change said colour relative to said luminosity;
- said pulse heights varying a saturation level of said at least one luminescent material thereby changing said colour.
4 more elements
Dependencies are inferred from the claim text.