A method of estimating the junction temperature of a light emitting diode comprises driving a forward bias current through the diode, the current comprising a square wave which toggles between high and low current values (Ihigh, llow), the high current value (lhigh) comprising an LED operation curre
A method of estimating the junction temperature of a light emitting diode comprises driving a forward bias current through the diode, the current comprising a square wave which toggles between high and low current values (Ihigh, llow), the high current value (lhigh) comprising an LED operation current, and the low current value (ILOW) comprising a non-zero measurement current. The forward bias voltage drop (Vf) is sampled and the forward bias voltage drop (Vflow) is determined at the measurement current (ILOW)—The temperature is derived from the determined forward bias voltage drop.
대표청구항▼
1. A method of estimating the junction temperature of a light emitting diode, comprising: driving a forward bias current through the diode, the current comprising a square wave which toggles between high and low current values (Ihigh, Ilow), the high current value (Ihigh) comprising an LED operation
1. A method of estimating the junction temperature of a light emitting diode, comprising: driving a forward bias current through the diode, the current comprising a square wave which toggles between high and low current values (Ihigh, Ilow), the high current value (Ihigh) comprising an LED operation current, and the low current value (Ilow) comprising a non-zero measurement current:sampling a forward bias voltage drop (Vf), and determining the forward bias voltage drop (Vflow) at the measurement current (Ilow);deriving the temperature from the determined forward bias voltage drop; and wherein determining the forward bias voltage drop (Vf) comprises analysing the samples to find a forward bias voltage drop which corresponds to a peak in the number of occurrences of that voltage drop. 2. A method as claimed in claim 1, wherein the measurement current (Ilow) is less than or equal to 1 mA. 3. A method as claimed in claim 1, wherein analysing the samples comprises deriving a histogram. 4. A method as claimed in claim 1, further comprising using the derived temperature as a feedback control parameter for controlling the current supply to the diode. 5. A method as claimed in claim 1, wherein deriving the temperature from the determined forward bias voltage drop comprises converting the forward bias voltage drop to a temperature value using a transformation function that represents the voltage-temperature characteristics at the measurement current. 6. A method as claimed in claim 1, wherein the junction temperature estimation takes place while the LED is providing a desired light output, determined by the duty cycle and high current value of the forward bias current. 7. A method of estimating the junction temperature of a plurality of light emitting diodes of a module, comprising using the method as claimed in claim 1 for each light emitting diode of the module, wherein the method further comprises driving each light emitting diode of the module to the low current value simultaneously for a measurement cycle. 8. A method as claimed in claim 7, wherein the junction temperature estimation takes place while the LED is providing a desired light output, determined by the duty cycle and high current value of the forward bias current, and wherein each light emitting diode of the module is driven to the low current value simultaneously by providing at least one duty cycle control period with only the low current value. 9. A system for estimating the junction temperature of a light emitting diode, comprising: means for driving a forward bias current through the diode, the current comprising a square wave which toggles between high and low current values, the high current value (Ihigh) comprising an LED operation current, and the low current (Ilow) comprising a non-zero measurement current;means for sampling a forward bias voltage drop (Vf), and determining a forward bias voltage drop (Vflow) at the measurement current (Ilow);means for deriving the temperature from the determined forward bias voltage drop; and wherein the means for sampling comprises means for analysing the samples to find a forward bias voltage drop which corresponds to a peak in the number of occurrences of that voltage drop. 10. A system as claimed in claim 9, wherein the measurement current (Ilow) is less than or equal to 1 mA. 11. A system as claimed in claim 9, wherein the means for deriving the temperature from the determined forward bias voltage drop comprises a memory storing a transformation function that represents the voltage-temperature characteristics at the measurement current. 12. A system for estimating the junction temperature of a plurality of light emitting diodes of a module, comprising a system as claimed in claim 9, wherein the means for driving is adapted to drive each light emitting diode of the module to the low current value simultaneously for a measurement cycle. 13. A system as claimed in claim 12, adapted to implement the junction temperature estimation while the LED is providing a desired light output, determined by the duty cycle and high current value of the forward bias current, and wherein the means for driving is adapted to drive each light emitting diode of the module to the low current value simultaneously by providing at least one duty cycle control period with only the low current value. 14. A LED control system comprising: a system for estimating the junction temperature as claimed in claim 9, and an LED drive circuit for driving the LED in dependence on the estimated junction temperature.
연구과제 타임라인
LOADING...
LOADING...
LOADING...
LOADING...
LOADING...
이 특허에 인용된 특허 (3)
Allen,David, Jacketed LED assemblies and light strings containing same.
Hoogzaad, Gian; Schmitz, Hans; Langeslag, Wilhelmus H. M.; Surdeanu, Radu, LED driver circuit and method, and system and method for estimating the junction temperature of a light emitting diode.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.