Method and device for remote sensing and control of LED lights

• US 9,560,711 B2
• Filed: 03/09/2016
• Issued: 01/31/2017
• 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:
  US15/065,655
• Publication Number:
  US 20160192450A1
• Time in Patent Office: 328 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

A system and method of thermal management for an LED are provided. A method provided by the system includes (a) providing a forward drive current to power the LED, the forward drive current having a first LED operating current component; (b) detecting the first LED operating current component; (c) sensing a first thermal operating point of the LED; and (d) generating a temperature signal indicative of the first thermal operating point. The method also includes (e) determining a thermal operating range of the LED; (f) determining that the first thermal operating point of the LED is outside the thermal operating range of the LED; and (g) generating a first control setting configured to cause the LED to be driven at a second operating point, the second thermal operating point within the thermal operating range.

Claims

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

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

a power supply configured to provide a forward drive current to power the LED, the forward drive current having a first LED operating current component;

a sensor for detecting the first LED operating current component; and

a processor configured to;

receive the temperature signal from the temperature sensor;

receive a signal indicative of the first LED operating current component;

determine a thermal operating range of the LED;

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

generate a first control setting configured to adjust the first LED operating current component to a second LED operating current component, and to cause the LED to be driven at a second thermal operating point, the second thermal operating point within the thermal operating range.

2. The thermal-management circuit of claim 1, wherein the second thermal operating point is selected to cause the LED to operate as brightly as possible within the thermal operating range.

3. The thermal-management circuit of claim 1, further comprising a storage device for storing the thermal operating range of the LED.

4. The thermal-management circuit of claim 3, wherein the storage device comprises a look-up table.

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

and wherein

the processor is configured to;

receive an input signal indicative of an input voltage from the dimmer control circuit;

responsive to the input signal from the dimmer control circuit, generate a second control setting configured to cause the LED to operate at a single brightness-level setting;

compare the first control setting and the second control setting; and

responsive to comparing, generate a control signal to drive the LED based on the lesser of the first control setting and the second control setting.

6. The thermal-management circuit of claim 1, further comprising a comparison circuit for selecting the least one of:

a control setting associated with the dimmer setting;

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

a control setting associated with the thermal operating range; and

wherein

the processor is configured to generate a control signal based at least in part on the selection of the comparison circuit.

7. The thermal-management circuit of claim 1, wherein:

the processor is configured to receive a rectified signal from a first transformer, the rectified signal indicative of a rectified power output by the first transformer;

the circuit further comprises 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 processor to the regulator IC;

wherein

the processor 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.

8. The thermal-management circuit of claim 1, wherein:

the processor is configured to;

receive an input signal indicative of a dimmer setting of greater than 0 percent of a full 0-100 percent range of dimming and less than 100 percent of the full 0-100 percent range of dimming;

responsive to receiving the input signal, determine the full 0-100 percent range of dimming; and

generate the first control setting, wherein the first control setting is within the full 0-100 percent range of dimming.

9. The thermal-management circuit of claim 8, further comprising:

a duty-cycle estimator for estimating a duty cycle of the input signal;

an analyzer for determining whether the input signal was produced using an electronic or a magnetic transformer;

the processor is configured to;

estimate a duty cycle of the input signal;

determine that the input signal was produced by one of an electronic transformer or a magnetic transformer; and

responsive to determining, generate a control signal to cause the circuit to operate in a mode that is compatible with the one of the magnetic transformer or the electronic transformer.

10. The thermal-management circuit of claim 1, wherein:

the processor further comprises a generator circuit and is configured to generate a first control setting configured to adjust the forward drive current down, based on a comparison of the first LED operating current component with a threshold LED operating current component at a maximum safe operating condition;

whereby

the thermal-management circuit is configured to yield an LED operating lifetime of at least a predetermined value.

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

providing a forward drive current to power the LED, the forward drive current having a first LED operating current component;

detecting the first LED operating current component;

sensing a first thermal operating point of the LED;

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

determining a 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 first control setting configured to cause the LED to be driven at a second operating point, the second thermal operating point within the thermal operating range.

12. The method of claim 11, wherein determining the thermal operating range of the LED comprises referencing a look-up table.

13. The method of claim 12, wherein the lookup table comprises LED thermal-power data.

14. The method of claim 11, further comprising:

receiving an input signal indicative of an input voltage from a dimmer control circuit;

responsive to receiving the input signal from the dimmer control circuit, generating a second control setting configured to cause the LED to operate at a single brightness-level setting;

comparing the first control setting and the second control setting; and

responsive to the comparing, generating a control signal configured to drive the LED based on the lesser of the first control setting and the second control setting.

15. The method of claim 14, further comprising:

selecting the lowest of a brightness setting associated with the dimmer setting, a brightness setting associated with the first thermal operating point, and a brightness setting associated with the thermal operating range; and

wherein

generating the control signal is responsive to the selecting.

16. The method of claim 11, wherein generating the first control setting comprises generating a control setting configured to drive the LED at its maximum brightness level within the thermal operating range.

17. The method of claim 11, further comprising receiving an input signal indicative of a dimmer setting;

and wherein

generating a first control setting is responsive to the receiving.

18. The method of claim 17, wherein the selecting is performed by comparing digital identifiers associated with respective ones of the brightness setting associated with the dimmer setting, the brightness setting associated with the first thermal operating point, and the brightness setting associated with the thermal operating range.

19. The method of claim 11, further comprising:

receiving an input signal indicative of a dimmer setting of greater than 0 percent of a full 0-100 percent range of dimming and less than 100 percent of the full 0-100 percent range of dimming;

responsive to receiving the input signal, determining the full 0-100 percent range of dimming; and

generating the first control setting, wherein the first control setting is within the full 0-100 percent range of dimming.

20. The method of claim 18, further comprising:

estimating a duty cycle of the input signal;

determining that the input signal was produced by one of an electronic transformer or a magnetic transformer; and

responsive to determining, generating a control signal to cause the LED to operate in a mode that is compatible with the one of the magnetic transformer or the electronic transformer.