Thermal protection structure for multi-junction LED module

Patent metadata

Field	Value
Publication number	US-9504120-B2
Application number	US-201414556318-A
Country	US
Kind code	B2
Filing date	Dec 1, 2014
Priority date	Nov 2, 2011
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

A system includes a plurality of light-emitting devices electrically coupled together. A temperature of each of the light-emitting devices is correlated with a voltage of said light-emitting device. The system includes a current driver configured to control an amount of current through at least a subset of the light-emitting devices. The system includes electronic circuitry that is electrically coupled to the subset of the light-emitting devices. The electronic circuitry is configured to: measure a voltage of the subset of the light-emitting devices while the light-emitting devices are in operation; determine, based on the measured voltage, whether the subset of the light-emitting devices is hotter than an acceptable temperature threshold; and instruct the current driver to reduce the amount of current through the subset of the light-emitting devices if the subset of the light-emitting devices has been determined to be hotter than the acceptable temperature threshold.

First claim

What is claimed is:

1. A system, comprising:
a plurality of light-emitting devices all electrically coupled in series, wherein a temperature of each of the light-emitting devices is correlated with a voltage of said light-emitting device;
a current driver configured to control an amount of current through the plurality of light-emitting devices; and
electronic circuitry having two terminals directly connected to only a portion of the plurality of light-emitting devices to measure a voltage across the portion of the plurality of light-emitting devices while the plurality of light-emitting devices is in operation, wherein the electronic circuitry is configured to:
determine, based on the measured voltage of the portion of the plurality of light-emitting devices, whether the voltage of the portion of the plurality of light-emitting devices exceeds a predetermined voltage; and
instruct the current driver to reduce the amount of current through the plurality of light-emitting devices if the voltage of the portion of the plurality of light-emitting devices has been determined exceeds the predetermined voltage.

2. The system of claim 1 , wherein the portion of the light-emitting devices include light-emitting devices that are electrically located at one end of the plurality of the light-emitting devices.

3. The system of claim 2 , wherein the portion of the light-emitting devices is surrounded by the rest of the plurality of light-emitting devices.

4. The system of claim 2 , wherein the portion of the light-emitting devices include one or more light-emitting devices.

5. The system of claim 1 , wherein the current driver includes a transistor that is electrically coupled in series with the portion of the plurality of light-emitting devices.

6. The system of claim 1 , wherein the electronic circuitry includes one or more operational amplifiers.

7. The system of claim 1 , wherein the electronic circuitry includes a modulating device that is electrically coupled to the current driver.

8. The system of claim 7 , wherein the modulating device is configured to convert an analog signal to a digital signal equipped with a pulse-width modulation (PWM) such that as a temperature of the portion of the plurality of light-emitting devices rises, the modulating device responds with a decreasing on-duty-cycle of PWM.

9. The system of claim 1 , wherein the predetermined voltage is correlated with a predefined constant temperature, or a detected temperature of one or more of the plurality of light-emitting devices that are not in the portion of the plurality of light-emitting devices.

10. A system, comprising:
a plurality of light-emitting devices all electrically coupled in series and disposed on a substrate and electrically coupled in series, wherein a temperature of each of the plurality of light-emitting devices corresponds with a voltage of said light-emitting device;
first electrical circuitry configured to control an amount of current that flows through the plurality of light-emitting devices; and
second electrical circuitry having two terminals directly connected to the only a portion of the plurality of light-emitting devices to measure a voltage across the portion of plurality of light-emitting devices while the plurality of light-emitting devices is in operation, wherein the second electrical circuitry is configured to:
compare the measured voltage of the portion of the plurality of light-emitting devices with a predetermined voltage that corresponds to a temperature threshold; and
send a feedback signal to the first electrical circuitry based on results of the comparison;

wherein the first electrical circuitry adjusts the amount of the current that flows through the plurality of light-emitting devices in response to the feedback signal.

11. The system of claim 10 , wherein:
the second electrical circuitry sends the feedback signal to instruct the first electrical circuitry to reduce the amount of current if the results of the comparison indicates that the measured voltage exceeds the predetermined voltage; and
the first electrical circuitry reduces the amount of the current in response to the feedback signal.

12. The system of claim 10 , wherein the portion of the light-emitting devices is surrounded by the rest of the plurality of lighting-emitting devices not in the portion of the plurality of light-emitting devices.

13. The system of claim 10 , wherein the first electrical circuitry includes a transistor that is electrically coupled in series with the portion of the light-emitting devices.

14. The system of claim 10 , wherein the second electrical circuitry includes a modulating device that is electrically coupled to the first electrical circuitry.

15. The system of claim 14 , wherein the modulating device is configured to convert an analog signal to a digital signal equipped with a pulse-width modulation (PWM) such that as a temperature of the portion of the plurality of light-emitting devices rises, the modulating device responds with a decreasing on-duty-cycle of PWM.

16. The system of claim 10 , wherein the temperature threshold is one of: a predefined constant temperature, or a measured temperature of one or more of the light-emitting devices that are not in the portion of the plurality of light-emitting devices.

17. A method, comprising:
measuring a voltage of only a portion of a plurality of light-emitting devices while the plurality of light-emitting devices are in operation;
comparing the measured voltage with a predetermined voltage that corresponds to a temperature threshold; and
adjusting, via a feedback mechanism, the driving condition of the plurality of light-emitting devices based on results of the comparing,
wherein the plurality of light-emitting devices are all electrically coupled in series.

18. The method of claim 17 , wherein the portion of the light-emitting devices are surrounded by the rest of the light-emitting devices that are not in the portion of the plurality of light-emitting devices.

19. The method of claim 17 , wherein the feedback mechanism includes a current driver that reduces an amount of current flowing through the plurality of light-emitting devices in response to the results of the comparing indicating that the temperature of the portion of the plurality of light-emitting devices is greater than a threshold.

20. The method of claim 19 , wherein the threshold is one of: a predefined constant temperature, or a measured temperature of one or more of the light-emitting devices that are not in the portion of the plurality of light-emitting devices.

Assignees

• Tsmc Solid State Lighting Ltd
• Epistar Corp

Inventors

• Yeh Wei-Yu

Classifications

• Y02B20/341

  Cross-Sectional Technologies · mapped topic

• H05B33/0851

  Electricity · mapped topic

• H05B33/089 Primary

  Electricity · mapped topic

• H05B45/56 Primary

  involving measures to prevent abnormal temperature of the LEDs · CPC title

• H05B45/18

  using temperature feedback · CPC title