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

• US 9,788,382 B2
• Filed: 02/19/2016
• Issued: 10/10/2017
• 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:
  US15/048,217
• Publication Number:
  US 20160174324A1
• Time in Patent Office: 599 Days
• 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 pre-defined LED set-point temperature;

a thermal sensor thermally exposed to the LED;

a current regulator interoperably coupled to the voltage source, the thermal sensor, and 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;

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; and

wherein current supplied to the LED is not increased beyond a maximal current level.

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; and

the activation of the switch results in transmission of a signal to the current regulator.

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, wherein the current regulator comprises a potentiometer.

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;

responsive to a determination that the sensed temperature exceeds the pre-defined set-point temperature, transmitting a first signal from the thermal sensor to a current regulator;

transmitting a second signal from the current regulator to a voltage source in response to the first signal; and

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

responsive to a determination that the sensed temperature is less than a second pre-defined temperature, transmitting a third signal from the thermal sensor to the current regulator, the second pre-defined temperature being less than the pre-defined set-point temperature;

transmitting a fourth signal from the current regulator to the voltage source in response to the third signal;

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

wherein current supplied to the LED is not increased beyond a maximal 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 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 a range of about 260 mA to about 330 mA.

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

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

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

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

19. A circuit comprising:

a voltage source;

a light-emitting diode (LED) having a pre-defined LED set-point temperature;

a thermal sensor thermally exposed to the LED, the thermal sensor comprises a switch adapted to activate responsive to the pre-defined LED set-point temperature being exceeded, the activation of the switch results in transmission of a signal to a current regulator;

the current regulator being interoperably coupled to the voltage source, the thermal sensor, and 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;

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; and

wherein current supplied to the LED is not increased beyond a maximal current level.