Methods and systems for maintaining the illumination intensity of light emitting diodes
View Patent ↗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.
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;
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 an LED illumination intensity to be not less than the minimal intensity level at the 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; 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:
establishing a pre-defined set-point temperature that correlates to a desired minimal intensity level of an LED;
sensing, via a thermal sensor, a temperature proximal to the LED;
determining whether a sensed temperature exceeds the pre-defined set-point temperature that correlates to the minimal intensity level of the LED;
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; and
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.