Light emitting diode replacement lamp
View Patent ↗Thermal management and control techniques for light emitting diode and other incandescent replacement light technologies using a current controller are disclosed.
1. A method for regulating current drive through at least one light emitting diode to compensate for temperature induced resistance changes in the light emitting diode, comprising:
supplying a source voltage;
using the source voltage to create a regulated current that is usable by the light emitting diode;
applying the regulated current to the light emitting diode to cause the regulated current to flow through the light emitting diode;
generating a sense voltage that is related to the regulated current and to a temperature at a position in a thermal pathway of heat emanating from the light emitting diode which heat is produced by the light emitting diode responsive to the regulated current; and
using the sense voltage as a feedback to modify the regulated current to be maintained within a non-destructive operating range of the light emitting diode when the regulated current would otherwise be outside of the non-destructive range due to a decreased resistance of the light emitting diode caused by an increased temperature of the light emitting diode.
2. A method as defined in claim 1 wherein the sense voltage is generated by at least a portion of the regulated current flowing through a temperature dependent resistance located in said thermal pathway.
3. A method as defined in claim 2 wherein generating the sense voltage includes selecting the temperature dependent resistance as having a positive temperature coefficient that causes the resistance of the temperature dependent resistance to increase with increases in temperature.
4. A method as defined in claim 2 wherein generating the sense voltage includes selecting the temperature dependent resistance as having a negative temperature coefficient that causes the resistance of the temperature dependent resistance to decrease with increases in temperature.
5. A method as defined in claim 2 wherein generating the sense voltage includes arranging the temperature dependent resistance in parallel with a parallel resistor and wherein the sense voltage is generated at least partially by the regulated current flowing through the temperature dependent resistance and the parallel resistor.
6. A method as defined in claim 5 wherein arranging includes configuring the temperature dependent resistance and parallel resistor in series with a series resistor and wherein the sense voltage is generated by the regulated current flowing through the temperature dependent resistance, the parallel resistor and series resistor.
7. A method as defined in claim 1 wherein the sense voltage is generated based on the regulated current flowing through a non-temperature dependent resistance.
8. A method as defined in claim 7 wherein generating the sense voltage includes amplifying the regulated current flowing through the non-temperature dependent resistance to produce the sense voltage and where an amplitude of the amplification is dependent at least partially on a temperature dependent resistance.
9. A method as defined in claim 8 wherein amplifying includes applying a negative feedback loop in the amplification based on the temperature dependent resistance.
10. A method as defined in claim 9 including arranging the temperature dependent resistance in the negative feedback loop with a negative temperature coefficient that causes the resistance of the temperature dependent resistance to decrease with increased temperature.
11. A method as defined in claim 9 further comprising: arranging the temperature dependent resistance in the negative feedback with a positive temperature coefficient that causes the resistance of the temperature dependent resistance to increase with increased temperature.
12. A current regulator for regulating current drive through at least one light emitting diode to compensate for temperature induced resistance changes in the light emitting diode, the current regulator comprising:
a source voltage input for receiving a source voltage from a voltage source;
a voltage regulator connected to the source voltage input for regulating the source voltage to create the regulated current and for connection to the light emitting diode to cause the regulated current to flow through the light emitting diode; and
a sense voltage generator for generating a sense voltage that is related to the regulated current and to a temperature at a position in a thermal pathway of heat emanating from the light emitting diode, which heat is produced by the light emitting diode responsive to the regulated current, where the sense voltage is used as a feedback to modify the regulated current to be maintained within a non-destructive operating range of the light emitting diode when the regulated current would otherwise be outside of the non-destructive range due to a decreased resistance of the light emitting diode caused by an increased temperature of the light emitting diode.
13. A current regulator as defined in claim 12 , further comprising:
a temperature dependent resistor positioned in said thermal pathway and wherein the sense voltage generator generates the sense voltage based on at least a portion of the regulated current flowing through the temperature dependent resistor.
14. A current regulator as defined in claim 13 wherein the temperature dependent resistor has a positive temperature coefficient.
15. A current regulator as defined in claim 13 wherein the temperature dependent resistor has a negative temperature coefficient.
16. A current regulator as defined in claim 13 , further comprising:
a parallel resistor and wherein the temperature dependent resistor is arranged in parallel with the parallel resistor and the sense voltage is generated by at least a portion of the regulated current flowing through the temperature dependent resistor and the parallel resistor.
17. A current regulator as defined in claim 12 ,
wherein the sense voltage generator includes an amplifier for generating the sense voltage based at least in part on the regulated current flowing through a non-temperature dependent resistor.
18. A current regulator as defined in claim 17 wherein the gain of the amplifier is dependent on a temperature dependent resistor positioned in said thermal pathway.
19. A current regulator as defined in claim 18 wherein the temperature dependent resistor has a positive temperature coefficient that causes the resistance of the temperature dependent resistor to increase with increases in temperature.
20. A current regulator as defined in claim 18 wherein the temperature dependent resistor has a negative temperature coefficient that causes the resistance of the temperature dependent resistor to decrease with increases in temperature.