LED lighting device with temperature dependent output stabilizer
AssigneeKoninklijke Philips N.V.
InventorsBerend Jan Willem Ter Weeme, William Peter Mechtildis Marie Jans
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Abstract
A lighting device has a plurality of LEDs of at least two types connected in series. At least one of the LEDs of the first type and LEDs of the second type is connected in parallel to a resistor assembly, such that the temperature-dependent resistance of the resistor assembly stabilizes a ratio of luminous flux output at different junction temperatures of the LEDs.
Claims13
A lighting device comprising a plurality of light emitting diodes, LEDs, the lighting device comprising:
- a first LED assembly comprising at least one LED of a first type having a varying first luminous flux output as a function of its junction temperature;
- a second LED assembly comprising at least one LED of a second type having a varying second luminous flux output as a function of its junction temperature different from the first luminous flux output of the first LED assembly as a function of its junction temperature,
- wherein the first LED assembly is connected in series to the second LED assembly, and wherein at least one of the LEDs of the first type and LEDs of the second type is connected in parallel to a resistor assembly having a temperature dependent resistance, the temperature dependence of the resistance being adapted to increase a stabilization of, within a predetermined range, a ratio of the first luminous flux output to the second luminous flux output at different junction temperatures of the first LED assembly and the second LED assembly.
A method of producing a lighting device comprising a plurality of light emitting diodes, LEDs, the method comprising:
- providing a first LED assembly comprising at least one LED of a first type having a varying first luminous flux output as a function of its junction temperature;
- providing a second LED assembly comprising at least one LED of a second type having a varying second luminous flux output as a function of its junction temperature different from the first luminous flux output of the first LED assembly as a function of its junction temperature;
- connecting the first LED assembly in series to the second LED assembly;
- connecting at least one of the LEDs of the first type and the LEDs of the second type in parallel to a resistor assembly having a temperature-dependent resistance;
- and
- adapting the temperature dependence of the resistance to increase a stabilization of, within a predetermined range, a ratio of the first luminous flux output to the second luminous flux output at different junction temperatures of the first LED assembly and the second LED assembly.
Dependencies are inferred from the claim text.