Methods and systems for maintaining the illumination intensity of light emitting diodes

• US 10,231,308 B2
• Filed: 09/07/2017
• Issued: 03/12/2019
• Est. Priority Date: 09/24/2008
• Status: Active Grant

• Current Assignee: Luminator Holding LP (LTG Acquisition, Inc.)
• Original Assignee: Luminator Holding LP (LTG Acquisition, Inc.)
• Inventors: Zlotnikov, Vadim, Gunter, John B., Coker, Jim, Berman, George, Berger, Valeriy K.
• Primary Examiner(s): Richardson, Jany
• Application Number:
  US15/698,207
• Publication Number:
  US 20170374717A1
• Time in Patent Office: 551 Days
• Field of Search: None
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs

Abstract

Systems and methods for maintaining the illumination intensity of one or more LEDs above a minimal intensity level. The systems and methods may include: (1) a current regulator for regulating the current in a circuit; (2) a voltage source for applying current to a circuit; (3) an LED with a minimal intensity level that correlates to a set-point temperature; and (4) a thermal sensor that is in proximity to the LED and adapted to sense a temperature proximal to the LED. The thermal sensor may transmit a signal to the current regulator if the sensed temperature exceeds the set-point temperature. Thereafter, the current regulator may take steps to regulate the current in order to maintain the LED illumination intensity above the minimal intensity level.

Claims

1. A circuit comprising:

a voltage source;

a light-emitting diode (LED) having a desired minimal intensity level associated therewith, the desired minimal intensity level being correlated to a pre-defined LED set-point temperature;

a thermal sensor in proximity to the LED and adapted to sense a temperature proximal to the LED;

wherein, responsive to a sensed temperature greater than the pre-defined LED set-point temperature, current supplied to the LED is increased in a step-wise manner from an original current level to an increased current level; and

wherein, responsive to a sensed temperature less than a second pre-defined LED temperature, current supplied to the LED is decreased in a step-wise manner from the increased current level to the original current level, the second pre-defined LED temperature being less that the pre-defined LED set-point temperature.

2. The circuit of claim 1, wherein:

the thermal sensor comprises a switch adapted to activate responsive to the pre-defined LED set-point temperature being exceeded.

3. The circuit of claim 1, wherein the thermal sensor comprises a resistor programmable SOT temperature switch.

4. The circuit of claim 1, wherein the thermal sensor is positioned adjacent an LED junction of the LED.

5. The circuit of claim 1, wherein the thermal sensor senses an LED-junction temperature.

6. The circuit of claim 1, wherein the circuit comprises a plurality of LEDs.

7. The circuit of claim 6, wherein the thermal sensor is positioned in proximity to the plurality of LEDs and senses a temperature proximal to the plurality of LEDs.

8. The circuit of claim 6, comprising:

a plurality of thermal sensors; and

wherein each of the plurality of thermal sensors is positioned in proximity to an LED of the plurality of LEDs and senses a temperature proximal to the LED.

9. The circuit of claim 1, wherein the voltage source is a battery.

10. The circuit of claim 1, comprising a current regulator.

11. A method comprising:

sensing, via a thermal sensor, a temperature proximal to an LED;

determining whether a sensed temperature exceeds a pre-defined set-point temperature that correlates to a minimal intensity level of the LED;

responsive to a determination that the sensed temperature exceeds the pre-defined set-point temperature,

increasing, in a step-wise manner, current level applied to the LED from a nominal level to an increased current level; and

responsive to a determination that the sensed temperature is less than a second pre-defined temperature,

decreasing, in a step-wise manner, current level applied to the LED from the increased current level to the nominal current level.

12. The method of claim 11, wherein the steps of claim 11 are repeated if the sensed temperature is determined to be not greater than the pre-defined set-point temperature.

13. The method of claim 11, wherein the increasing-current step causes an LED illumination intensity to be not less than the minimal intensity level.

14. The method of claim 11, wherein an increased current is in the range of about 260 mA to about 330 mA.

15. The method of claim 11, wherein the increasing-current step comprises increasing a voltage supplied a voltage source of a circuit associated with the LED.

16. The method of claim 11, wherein the increasing-current step comprises decreasing a resistance of a circuit associated with the LED.

17. The method of claim 11, wherein the sensing step comprises the thermal sensor sensing an LED junction temperature.

18. The method of claim 11, wherein the determining step is performed by the thermal sensor.