Method and device for remote sensing and control of LED lights

• US 9,326,346 B2
• Filed: 06/11/2015
• Issued: 04/26/2016
• Est. Priority Date: 01/13/2009
• Status: Active Grant

• Current Assignee: LEDVANCE LLC (MLS Co. Ltd.)
• Original Assignee: TerraLUX Incorporated
• Inventors: Catalano, Anthony W., Harrison, Daniel J., Davis, Steven S.
• Primary Examiner(s): PHAM, THAI N
• Application Number:
  US14/737,052
• Publication Number:
  US 20160066386A1
• Time in Patent Office: 320 Days
• Field of Search: 315/112, 315/117, 315/185.R, 315/224, 315/291, 315/297, 315/307, 315/308, 315/309
• US Class Current: 1/1
• CPC Class Codes: G01K 2217/00 Temperature measurement using electric or magnetic components already present in the system to be measured
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/18 using temperature feedback
• CPC Class Codes: H05B 45/3575 by means of dummy loads or bleeder circuits, e.g. for dimmers
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs

Abstract

Thermally managing at least one light-emitting diode (LED) receiving an operating current and/or an operating voltage and being operable at an operating temperature includes determining a current thermal operating point of the LED, obtaining a thermal operating range of the LED, and calculating a new operating point of the LED based on the current thermal operating point and the thermal operating range, wherein the new operating point is within the thermal operating range. A control signal is generated that adjusts power delivered to the LED to cause the LED to operate at the new operating point. Detection of the operating temperature of the LED may be based on the magnitude of a current pulse superimposed on the operating current provided to the LED and the magnitude of the voltage pulse across the LED resulting from the applied current pulse superimposed on the operating current.

Claims

1. A thermal-management system for an LED, the system comprising:

a temperature sensor configured to sense a first thermal operating point of the LED and generate a temperature signal indicative of the first thermal operating point;

a processing device configured to receive the temperature signal from the temperature sensor and a rectified signal from a first transformer, the rectified signal indicative of a rectified power output by the first transformer;

a regulator IC configured to receive the rectified power output from the first transformer and convert the rectified power output into a regulated power output, the rectified power output having one of a first frequency component or a second frequency component; and

an input/output link coupling the processing device to the regulator IC;

wherein the processing device is configured to;

responsive to receiving the rectified signal from the first transformer, determine that the first transformer is one of a magnetic transformer having the first frequency component or an electronic transformer having the second frequency component, and generate a first control signal to instruct the regulator IC to operate in a mode that is compatible with the one of the magnetic transformer or the electronic transformer;

determining a thermal operating range of the LED;

responsive to receiving the temperature signal from the temperature sensor and determining the thermal operating range of the LED, determine the first thermal operating point of the LED is outside the thermal operating range of the LED; and

generate a second control signal configured to calibrate the regulated power output whereby the LED is driven within the thermal operating range.

2. The system of claim 1, wherein:

the regulator IC is configured to receive a rectified power output from a second transformer;

the processing device is configured to receive a rectified signal from the second transformer; and

the processing device is configured to;

responsive to receiving the rectified signal from the second transformer, determine that the second transformer is the other one of a magnetic transformer having a frequency component of 120 Hz or less or an electronic transformer having a frequency component greater than 120 Hz.

3. The system of claim 2, wherein:

the processing device is configured to;

generate a second control signal to instruct the regulator IC to operate in a mode that is compatible with the other one of the magnetic transformer or the electronic transformer.

4. The system of claim 3, wherein:

the processing device is configured to;

generate a second control signal to instruct the regulator IC to operate in a mode that is compatible with the other one of the magnetic transformer or the electronic transformer.

5. The system of claim 1, further comprising a dimmer control circuit for dimming the LED in accordance with a dimmer setting.

6. The system of claim 5, wherein the second control signal is generated based at least in part on the dimmer setting or the first thermal operating point.

7. The system of claim 5, further comprising a comparison circuit for selecting the least one of:

a control signal associated with the dimmer setting;

a control signal associated with the first thermal operating point; and

a control signal associated with the thermal operating range; and

wherein

the processing device is configured to generate the second control signal based at least in part on the selection of the comparison circuit.

8. A method of thermal management for an LED, the method comprising:

sensing a first thermal operating point of the LED;

generating a temperature signal indicative of the first thermal operating point;

receiving a rectified signal from a first transformer, the rectified signal indicative of a rectified power output by the first transformer;

receiving the rectified power output from the first transformer;

converting the rectified power output into a regulated power output, the rectified power output having one of a first frequency component or a second frequency component;

responsive to receiving the rectified signal from the first transformer, determining that the first transformer is one of a magnetic transformer having the first frequency component or an electronic transformer having the second frequency component;

determining a thermal operating range of the LED;

responsive to receiving the temperature signal from the temperature sensor and determining the thermal operating range of the LED, determining that the first thermal operating point of the LED is outside the thermal operating range of the LED; and

generating a control signal configured to calibrate the regulated power output whereby the LED is driven within the thermal operating range.

9. The method of claim 8, wherein determining the thermal operating range of the LED comprises referencing a look-up table.

10. The method of claim 8, wherein:

the first frequency component comprises a frequency of 120 Hz or less; and

the second frequency component comprises a frequency greater than 120 Hz.

11. The method of claim 8, wherein sensing the first thermal operating point of the LED comprises receiving input from a thermal sensor.

12. The method of claim 8, wherein generating the control signal comprises generating a control signal its maximum brightness level within the thermal operating range.

13. The method of claim 8, wherein generating the control signal comprises generating a control signal based in part on a dimmer setting.

14. The method of claim 13, further comprising:

selecting the at least one of a regulated power associated with the dimmer setting, a regulated power associated with the first thermal operating point, and a regulated associated with the thermal operating range; and

generating the control signal based at least in part on the selecting.

15. The method of claim 14, wherein the selecting is performed by comparing digital identifiers associated with respective ones of the regulated power associated with the dimmer setting, the regulated power associated with the first thermal operating point, and the regulated power associated with the thermal operating range.

16. A thermal-management system for an LED, the system comprising:

a temperature sensor configured to sense a first thermal operating point of the LED and generate a input signal indicative of the first thermal operating point;

a processing device having a communications bus and configured to receive the input signal from the temperature sensor and a rectified signal from a first transformer, the rectified signal indicative of a rectified power output by the first transformer;

a regulator IC having a power input link configured to receive the rectified power output from the first transformer, and a power output link, the regulator IC configured to convert the rectified power output into a regulated power output, the rectified power output having one of a first frequency component or a second frequency component; and

an input/output link coupling the processing device to the regulator IC;

wherein

the processing device is configured to;

sample the rectified signal over a period of time;

responsive to sampling the rectified signal from the first transformer, determine that the first transformer is one of a magnetic transformer having the first frequency component or an electronic transformer having the second frequency component, and generate a first control signal to instruct the system to operate in one of a first mode or a second mode, the first mode compatible with the magnetic transformer wherein the processing device is responsive to a zero crossing duty cycle of the rectified signal, the second mode compatible with the electronic transformer wherein the processing device tracks a waveform of the rectified signal;

determining a thermal operating range of the LED;

responsive to receiving the input signal from the temperature sensor and retrieving the thermal operating range of the LED, determine the first thermal operating point of the LED is outside the thermal operating range of the LED; and

generate a second control signal configured to calibrate the regulated power output whereby the LED is driven within the thermal operating range.