Intelligent drive circuit for a light emitting diode (LED) light engine

• US 20060028155A1
• Filed: 08/09/2004
• Published: 02/09/2006
• Est. Priority Date: 08/09/2004
• Status: Active Grant

• Current Assignee: Dialight Corporation (Dialight PLC)
• Original Assignee: Dialight Corporation (Dialight PLC)
• Inventors: Young, Garrett
• Granted Patent: US 7,132,805 B2
• Time in Patent Office: Days
• US Class Current: 315/308
• 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 45/58 involving end of life detection of LEDs
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A controller for controlling a light emitting diode (LED) light engine. The controller includes a temperature sensor configured to sensor temperature at the LED light engine. A current sensor senses a drive current of the LED light engine. A voltage differential sensor senses a voltage differential across LEDs of the LED light engine. A timer monitors a time of operation of the LED light engine. Further, a control device controls the drive current to the LED light engine based on the sensed temperature, the sensed drive current, the sensed voltage differential, and the monitored time of operation. Further, the control device outputs an indication of intensity degradation of an LED, and if the intensity degradation exceeds a predetermined threshold the control can output an indication of such to a user, so that the user can be apprised that the LED needs to be changed.

Claims

1. A controller for controlling a light emitting diode (LED) light engine comprising:

a temperature sensor configured to sense temperature at the LED light engine;

a current sensor configured to sense a drive current of the LED light engine;

a voltage sensor configured to sense a voltage differential across LEDs of the LED light engine;

a timer configured to monitor a time of operation of the LED light engine; and

a control device configured to control the drive current to the LED light engine based on the sensed temperature, the sensed drive current, the sensed voltage differential, and the monitored time of operation such that the LED light engine outputs a same desired light output throughout its useful life.

2. A controller according to claim 1, wherein the control device controls the drive current of the LED light engine based on integrating the sensed drive current with respect to time.

3. A controller according to claim 1, wherein the control device controls the drive current to maintain a light output of an LED based on comparing the sensed temperature with stored intensity degradation factor data correlating an intensity degradation factor with temperature and a color of the LED.

4. A controller according to claim 1, wherein the control device controls the drive current to maintain a light output of an LED based on comparing the monitored time with stored data correlating an intensity degradation factor with time.

5. A controller according to claim 1, wherein the control device further outputs an indication if the intensity degradation factor data exceeds a predetermined threshold.

6. A controller according to claim 5, wherein the indication is a variation in intensity in the drive current to the LED light engine for a predetermined period of time in a transition of the LED light engine from an ON or OFF state.

7. A controller for controlling a light emitting diode (LED) light engine comprising:

a controller configured to determine if a degradation slope of the LED light engine exceeds a predetermined threshold, and configured to vary an intensity of a drive current to the LED light engine for a predetermined period of time in a transition of the LED light engine from an ON or OFF state when it is determined that the degradation slope exceeds the predetermined threshold.

8. A controller for controlling a light emitting diode (LED) light engine comprising:

means for sensing temperature at the LED light engine;

means for sensing a drive current of the LED light engine;

means for sensing a voltage differential across LEDs of the LED light engine;

means for monitoring a time of operation of the LED light engine; and

means for controlling the drive current to the LED light engine based on the sensed temperature, the sensed drive current, the sensed voltage differential, and the monitored time of operation such that the LED light engine outputs a same desired light output throughout its useful life.

9. A controller according to claim 8, wherein the means for controlling controls the drive current of the LED light engine based on integrating the sensed drive current with respect to time.

10. A controller according to claim 8, wherein the means for controlling controls the drive current to maintain a light output of an LED based on comparing the sensed temperature with stored intensity degradation factor data correlating an intensity degradation factor with temperature and a color of the LED.

11. A controller according to claim 8, wherein the means for controlling controls the drive current to maintain a light output of an LED based on comparing the monitored time with stored data correlating an intensity degradation factor with time.

12. A controller according to claim 8, wherein the means for controlling further outputs an indication if the intensity degradation factor data exceeds a predetermined threshold.

13. A controller according to claim 12, wherein the indication is a variation in intensity in the drive current to the LED light engine for a predetermined period of time in a transition of the LED light engine from an ON or OFF state.

14. A controller for controlling a light emitting diode (LED) light engine comprising:

means for controlling for determining if a degradation slope of the LED light engine exceeds a predetermined threshold, and for varying an intensity of a drive current to the LED light engine for a predetermined period of time in a transition of the LED light engine from an ON or OFF state when it is determined that the degradation slope exceeds the predetermined threshold.