Dimmable light source with temperature shift
First Claim
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1. An illumination device, comprising:
- input terminals of the illumination device for coupling to AC mains;
a light emitting diode (LED) string connected in series with the input terminals of the illumination device;
a rectifier, having input terminals which are connected in series with the LED string and the input terminals of the illumination device, and having output terminals;
a controllable voltage source, having input terminals coupled to the rectifier output terminals, and having output terminals; and
a series arrangement of at least one auxiliary LED and an auxiliary ballast resistor connected across the output terminals of the controllable voltage source.
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Abstract
An illumination device (1) comprises:
- input terminals (2) for coupling to AC mains;
- a LED string (10) connected in series with the input terminals;
- a rectifier (30), having input terminals connected in series with the LED string;
- a controllable voltage source (40), having input terminals coupled to the rectifier output terminals;
- a series arrangement of at least one auxiliary LED (51) and a second ballast resistor (52) connected to the output terminals of the controllable voltage source.
The voltage source comprises:
- a series arrangement of an adjustable first resistor (46) and a second resistor (47) connected in parallel to the input terminals;
- a tuneable Zener diode (49) connected in parallel to the output terminals, having a control input terminal (48) connected to the node between the two resistors; wherein positive output terminal is connected to positive input terminal and negative output terminal is connected to negative input terminal.
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Citations
20 Claims
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1. An illumination device, comprising:
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input terminals of the illumination device for coupling to AC mains; a light emitting diode (LED) string connected in series with the input terminals of the illumination device; a rectifier, having input terminals which are connected in series with the LED string and the input terminals of the illumination device, and having output terminals; a controllable voltage source, having input terminals coupled to the rectifier output terminals, and having output terminals; and a series arrangement of at least one auxiliary LED and an auxiliary ballast resistor connected across the output terminals of the controllable voltage source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An illumination device, comprising:
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first and second input terminals of the illumination device for coupling to an AC voltage supply; a rectifier having first and second input terminals and first and second output terminals; a light emitting diode (LED) string comprising at least a first series of LEDs; and a controllable source being one of a controllable voltage source and a controllable current source, the controllable source having a pair of input terminals and a pair of output terminals, wherein the pair of input terminals of the controllable source is connected across the first and second output terminals of the rectifier; and a series arrangement of at least one auxiliary LED and an auxiliary ballast resistor, wherein a series circuit is connected across the input terminals of the illumination device, the series circuit comprising; an input of the rectifier, the input of the rectifier being across the first and second input terminals of the rectifier, and the LED string, and wherein the series arrangement of the at least one auxiliary LED and the auxiliary ballast resistor is connected across the pair of output terminals of the controllable source. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An illumination device, comprising:
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first and second input terminals of the illumination device for coupling to AC mains; a light emitting diode (LED) string comprising at least a first series of LEDs; and a controllable AC source being one of a controllable AC voltage source and a controllable AC current source, the controllable AC source having first and second input terminals and first and second output terminals; and a series arrangement of at least one auxiliary LED and an auxiliary ballast resistor, wherein a series circuit is connected across the input terminals of the illumination device, the series circuit comprising; an input of the controllable AC source, the input of the controllable AC source being across the first and second input terminals of the controllable AC source, and the LED string, and wherein the series arrangement of the at least one auxiliary LED and the auxiliary ballast resistor is connected across the pair of output terminals of the controllable AC source. - View Dependent Claims (19, 20)
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Specification