Real-time monitoring of light emitting diode (LED) life

Abstract

In accordance with an example embodiment, there is disclosed herein a method for determining the degradation rate of a LED. The power consumed by the LED can be determined from the current passing through the LED and the voltage drop across the LED. The junction temperature of the LED is indirectly determined by obtaining a temperature reading pf the LED. Based on the temperature reading,, the LED junction temperature can be determined based on the thermal resistance of the LED.. The degradation rate is obtained based on the LED junction temperature and the power consumed by the LED. In particular embodiments, the remaining life of the LED is also determined.

Description

Real-Time Monitoring of Light Emitting Diode (LED) LifeTECHNICAL FIELD

[0001] The present disclosure relates generally to monitoring the age, or remaining life, of a light emitting diode (LED) that can be employed in airfield lighting fixtures.BACKGROUND

[0002] LED lights degrade over time and at some point, the light output will diminish to a point that is considered “end of life” (EOL). The EOL threshold varies and can be based on such things as industry standards (e.g., L70 rating), the application, and the light fixture manufacturer’s recommendations. The rate at which a LED light ages is determined by several factors, including discrete LED junction temperature, discrete LED design, light engine design, discrete LED current, and / or moisture (humidity), vibration and other factors.

[0003] To measure the age of a light, the light output is directly measured using a device in a laboratory with controlled variables such as temperature, distance, angle, and calibrated instruments. However, in the field and specifically at an airport, it is simply not practical or possible to make such a measurement.OVERVIEW OF EXAMPLE EMBODIMENTS

[0004] The following presents a simplified overview of the example embodiments in order to provide a basic understanding of some aspects of the example embodiments. This overview is not an extensive overview of the example embodiments. It is intended to neither identify key or critical elements of the example embodiments nor delineate the scope of the appended claims. Its sole purpose is to present some concepts of the example embodiments in a simplified form as a prelude to the more detailed description that is presented later.

[0005] In accordance with an example embodiment, there is disclosed herein amethod for determining the degradation rate of a LED. The power consumed by the LED can be determined from the current passing through the LED and the voltage drop across the LED. The junction temperature of the LED is indirectly determined by obtaining a temperature reading of the LED. Based on the temperature reading, the LED junction temperature can be determined based on the thermal resistance for the LED. The degradation rate is obtained based on the LED junction temperature and the power consumed by the LED. In particular embodiments, the remaining life of the LED is also determined.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The accompanying drawings incorporated herein and forming a part of the specification illustrate the example embodiments.

[0007] FIG. 1 is a block diagram illustrating an example of a system that comprises a printed circuit board (PCB) with a light emitting diode mounted thereon upon which an example embodiment can be implemented.

[0008] FIG. 2 is a block diagram illustrating an example of a system that comprises a printed circuit board (PCB) with a string of light emitting diodes mounted thereon upon which an example embodiment can be implemented.

[0009] FIG. 3 is a block diagram illustrating a simplified example of an airfield lighting system with a light fixture capable of implementing an example embodiment.

[0010] FIG. 4 is a block diagram illustrating a methodology.

[0011] FIG. 5 is a block diagram of a computer system upon which an example embodiment can be implemented.DESCRIPTION OF EXAMPLE EMBODIMENTS

[0012] This description provides examples not intended to limit the scope of the appended claims. The figures generally indicate the features of the examples, where it is understood and appreciated that like reference numerals are used to refer to like elements. Reference in the specification to "one embodiment" or "an embodiment" or“an example embodiment” means that a particular feature, structure, or characteristic described is included in at least one embodiment described herein and does not imply that the feature, structure, or characteristic is present in all embodiments described herein.

[0013] In an example embodiment, indirect monitoring of an LED using the LED junction temperature is employed to determine the age of the light. A measurement is taken periodically and integrated over time to track the LED's degradation rate and estimate its remaining life. While this method may not be as precise as direct measurement of the LED, monitoring the LED junction temperature can provide information about the LED's performance and lifespan. By regularly monitoring the LED junction temperature, maintenance personnel can determine the age LED lights and proactively replace LED lights before they reach their end of life, reducing the risk of unexpected failures and ensuring that the lighting system remains reliable and effective.

[0014] In an example embodiment, the LED power supplies operates open loop and does not directly measure or report the LED current to a microcontroller or other device outside of the LED driver. Therefore, the current used for calculations described herein are based on commanded current settings to the LED driver. Therefore, no current measurement is used for this method.

[0015] In an example embodiment, pulse width modulation (PWM) is employed to control the brightness of the LED. Therefore, the current provided by the power supply to the LED can remain constant over various brightness settings.

[0016] In an example embodiment, the LED power dissipation is determined by:

[0017] P=((Vanode — Vcathode) / n) X ILED

[0018] where P is the LED power dissipation, Vanode is the voltage at the start of the LED string, Vcathode is the voltage at the end of the LED string, n is an integer greater than zero and is the number of LEDs in the string, and ILED is the LED command current.

[0019] In an example embodiment, a temperature sensor is located on the PCB in proximity of a discrete LED, In particular embodiments, the temperature is obtainedat a point referred to herein as the LED Temperature Soldering Point (or “Tsp”). This point is used to determine the LED junction temperature (Tj) and is located on the LED PCB (Printed Circuit Board) at a location that is very close to a LED (which depends on the accuracy of the temperature sensor, for example for IR (infra-red) sensors the range would be between 1 to 2 cm) and in some embodiments is connected by a copper pour to the LED. A measuring point that is located remotely (e.g., off the LED, PCB or not connected by a copper pour) may not allow an accurate junction temperature measurement. T

[0020] The LED junction temperature is determined by:

[0021] Tj = TSP + (Rth j-sp x P)

[0022] where Rth j-sp is the thermal resistance from TSP to the LED junction. This parameter can be found in the data sheet of the LED and represents the thermal performance of the LED.

[0023] The LED's degradation rate is a measure of how quickly its light output decreases over time. It can be calculated using the following formula (Arrhenius model):

[0024] D = A * exp(-Ea / (k * Tj))

[0025] where D is the degradation rate, A is a constant (e.g., a pre-exponential factor that can be determined by the datasheet for the LED or by experimentation), Eais the activation energy (determined by the LED datasheet or by experimentation), k is the Boltzmann constant, and Tj is the LED junction temperature. In some embodiments, the A and Eavariables can be affected outside of temperature (e.g., vibration, humidity) and these inputs can be monitored and adjusted in real time. Additionally, there are some equations from manufacturers that can be used for determining A and Ea.

[0026] The present life of the LED is calculated whenever the TSP is determined. For example the present life can be updated as Present Life - D*Timeon. In particular embodiments, where pulse width modulation is employed to control the brightness of the LED, the time period for Timeon is adjusted by the pulse width duty cycle, e.g., the Timeon * %Pulse width.

[0027] Upon updating the present life, the updated present life can be compared with a preset threshold to determine if the LED is reaching the end of its recommended end of life. In an example embodiment, the present life is compared to the L70 rating from the manufacturer to determine where the LED life is and assist in determining whether the LED should be replaced..

[0028] In an example embodiment, a system is designed to inform end-users of runway lighting systems about the condition of individual lights in terms of their apparent age. Lights are equipped with sensors that measure various parameters and calculate their current apparent age, which is then reported to a central data gathering point. This information is typically used to alert the user when the recommended end- of-life has been reached for each light, as well as to show the user the aging rate based on current use conditions. For example, a high aging rate may be indicated if the lights are used at the highest setting on a hot day.

[0029] The data collected is used by the end-user to schedule light maintenance, control light inventory, and make informed decisions about how to best maintain the runway lights for a longer lifespan. By monitoring the age and performance of individual lights, the end-user can proactively replace lights before they fail, reducing the risk of unexpected outages and ensuring a reliable and effective lighting system for aircraft operations. Additionally, the system helps guide the user to the best practices to maintain a longer life for the runway lights.

[0030] FIG. 1 is a block diagram illustrating an example of an airfield lighting fixture 100 that comprises a printed circuit board (PCB) 108 with a light emitting diode 102 mounted thereon upon which an example embodiment can be implemented. A voltage drop across the diode is determined by the voltage difference between the anode 104 and cathode 106 of the LED 102. LED electronics 110 comprise electronics, such as for example a driver circuit, for operating the LED 102. Logic 112, which may also be referred to herein as ‘light fixture logic.’ is coupled with the LED and provides the functionality described herein. “Logic”, as used herein, includes but is not limited to hardware, firmware, software and / or combinations of each to perform a function(s) or an action(s), and / or to cause a function or action from another component. Forexample, based on a desired application or need, logic may include a software controlled microprocessor, discrete logic such as an application specific integrated circuit (ASIC), a programmable / programmed logic device, memory device containing instructions, or the like, or combinational logic embodied in hardware. Logic may also be fully implemented in software that is embodied on a tangible, non-transitory computer-readable medium that performs the described functionality when executed by one or more processors.

[0031] The light fixture logic 112 is coupled with communication interface 120, which is coupled with a communication link represented by 122. The communication interface 120 and communication link 122 can employ any suitable wired or wireless protocol enabling the airfield fixture logic 112 to communicate with external devices. In an example embodiment, the communication interface 120 and communication link 122 employ powerline communications for communicating with external devices.

[0032] In an example embodiment, the light fixture logic 112 is operable to obtain data representative of at least one operating condition for the light emitting diode 102, determine a current aging status (examples are provided herein infra) for the light emitting diode 102 based on the data representative of the at least one operating condition, and the send data representative of aging status to an airfield lighting controller (not shown, see e.g., ref. 304 in FIG. 3) that is located remotely from the airfield lighting fixture 100 via communication interface 120 and communication link 122.

[0033] In an example embodiment, the data representative of aging status is provided in real-time. In other embodiments, the data representative of the aging status is provided in any desired periodic or aperiodic time periods.

[0034] In an example embodiment, the data representative of the aging status is sent by the airfield light fixture 100 to the airfield lighting controller via powerline communication. In another example embodiment, the data representative of the aging status is sent via a wireless communication. In yet another example embodiment, the data representative of the aging status is sent via a signal line communication. In still yet another example embodiment, the aging status is sent by a combination of at leasttwo of a powerline communication, a wireless communication, and / or a signal line communication.

[0035] In an example embodiment, the airfield lighting logic 112 is operable to send to the controller a notification upon determining that the aging status of the light emitting diode is less than a predefined threshold. For example, when the remaining life of the LED 102 is less than 80% or 70% which may be dependent upon the regulatory environment where the airfield light fixture 100 is deployed.

[0036] In an example embodiment, the light fixture 100 comprises a temperature sensor 114 that senses the temperature at a temperature soldering point (Tsp) 116. In the illustrated example, a voltage sensor 118 senses a voltage drop across the light emitting diode (Vanode - Vcathode). The logic 112 is coupled with the temperature sensor 114 and the voltage sensor 118.

[0037] In an example embodiment, which will be further described in FIG. 3, the airfield lighting fixture 100 provides operating parameters, such as temperature (ambient and / or Tsp), current ID through LED 102, and / or the voltage drop across the LED 102 to a remotely located controller or other device that determines the aging status for the LED 102.

[0038] In an example embodiment, the logic 112 is operable to obtain data representative of a voltage drop from the voltage sensor 118. The logic 112 is operable to obtain data representative of a current passing through the LED 102. The logic 112 is further operable to determine the power consumed by the LED 102 based on the data representative of a voltage drop across the LED 102 and the data representative of a current passing through the LED 102.

[0039] The logic 112 is operable to determine a junction temperature (Tj) for the LED 102 based on the data representative of the temperature at the soldering point (TSP), a thermal resistance of the LED 102, and the power consumed by the LED 102. In an example embodiment, this is calculated by Tj = TSP + (Rth j-sp x P).

[0040] The logic 112 is operable to determine a degradation rate (D) for the LED based on the junction temperature. In an example embodiment, this is calculated byD = A * exp(-Ea / (k * Tj)) as described herein.

[0041] The logic 112 is operable to determine a present life of the light emitting diode based on the degradation rate. In an example embodiment, this is calculated as

[0042] In an example embodiment, the logic 112 is operable to communicate with an external controller (not shown, see e.g., FIG. 3 or FIG. 4) to obtain the representative of the current for the LED 102. For example, the current can set a current (the commanded set current) for operating the LED 102.

[0043] In an example embodiment, the temperature sensor 114 is within one to two centimeters of the soldering point 116. In particular embodiments, the soldering point 116 is coupled with a copper pour (202; FIG. 2) on the PCB 108.

[0044] In an example embodiment, the logic 112 is operable to send data representative of the degradation rate to a remote computer (not shown, see e.g., FIGS. 3 and 4). In another example embodiment, the logic 112 is operable to send the present life to the remote computer. In still another embodiment, the logic 112 is operable to send both the degradation rate and the present life to the remote computer. In particular embodiments, the logic 112 is operable to send a notification to the remote computer responsive to determining that the present life is less than a predetermined threshold. For example, if the present life is less than recommended end of life. In particular embodiments, the recommended end of life threshold is the L70 rating (or 70%). The logic 112 can employ any suitable technique for sending the aforementioned data to the remote computer, including but not limited to, powerline communications, wireless communications, and / or signal line communications.

[0045] FIG. 2 is a block diagram illustrating an example of a system 200 that comprises a printed circuit board (PCB) 108 with a string of LEDs (D1 ,,, Dn, where n is an integer greater than 1 ) 102 mounted thereon. The string of LEDs (D1-Dn) comprises a first diode D1 and a last diode Dn. The string may comprise zero to any physically realizable number of LEDs 102 between the first diode D1 and the last diode Dn. For a string of LEDs 102, the voltage drop used for calculating the power consumed by a LED 102 is determined by the difference between the voltage at the anode 104 of D1 and the voltage at the cathode 106 of Dn, divided by the number ofLEDs 102 in the string.

[0046] In the example illustrated in FIG. 2 the PCB 108 further comprises a copper pour 202 Although the copper pour 202 is illustrated as above PCB 108, those skilled in the art can readily appreciate that a PCB may comprise several layers and the copper pour 202 can be located at any desired layer.

[0047] As those skilled in the art can readily appreciate, although the examples illustrated herein measure the soldering point temperature at the cathode 106 of diodes 102, this is merely for ease of illustration. Those skilled in the art should readily appreciate that the temperature solder point can be located at the anode 104 of the diodes 102. Thus, this disclosure should not be construed as limiting the temperature solder point 116 to the areas indicated on the figures herein.

[0048] FIG. 3 is a block diagram illustrating an example of a simplified airfield lighting system 300 with a light fixture 302 capable of implementing an example embodiment. The light fixture 302 comprises a PCB 108 with a string of LEDs (D1-Dn) 102 as described in FIG. 2 herein.

[0049] An airfield controller 304 is operable to receive inputs from a user. The inputs include commands for controlling the operation of the LEDs 102 and provides operating parameters such as intensity and blink rate.

[0050] The controller 304 is coupled with a current source 306 for the light fixture 302. In an example embodiment, the current source is a constant current regulator (CCR).

[0051] Current from the current source 306 is provided to a current transformer 308 which is coupled to the light fixture 302 via plugs 310. In an example embodiment, powerline communications are employed to transmit the data between the controller 304 and the light source 302. For example, operating parameters can be transmitted from the controller 304 to the light fixture 302. Data, such as present life and deterioration rate can be transmitted from the logic 112 in light fixture 302 to controller 304.

[0052] The controller 304 comprises logic 314 that is operable to implement thefunctionality described herein for controller 304 and a user interface 316. The user interface 316 can provide audio, visual, or audiovisual signals representative of the aging status of the LED 102. In an example embodiment, the user interface 316 may be co-located with the controller 304 as shown in the illustrated example. Those skilled in the art can readily appreciate that the user interface 316 can be located remotely from the controller 304, or additional user interfaces 316 can be located remotely from the controller 304.

[0053] In an example embodiment, as described in FIG. 1 , the controller 304 obtains data representative of the aging status for the LED 102 from the light fixture logic 112. The controller is operable to output data representative of the aging status of LED 102 on user interface 316. In another example embodiment, the controller 304 obtains, data representative of at least one operating condition for the light emitting diode 102 and determines the current aging status for the light emitting diode 102 based on the data representative of the at least one operating condition, and outputs on the user interface 316, data representative of the aging status for the light emitting diode.

[0054] In an example embodiment, the data representative of the at least one operating condition is provided in real-time. In other embodiments, the data representative of the at least one operating condition is provided at any desired periodic or aperiodic time period.

[0055] In an example embodiment, the data representative of the at least one operating condition is sent by the airfield light fixture 302 to the airfield lighting controller via powerline communications. In another example embodiment, the data representative of the at least one operating condition is sent via wireless communications. In yet another example embodiment, the data representative of the at least one operating condition is sent via a signal line communication. In still yet another example embodiment, the data representative of the at least one operating condition is sent by a combination of powerline, wireless, and / or signal line communications.

[0056] In an example embodiments, the logic 314 obtains data representative of the power consumption (or the appropriate variables for computing power consumption)and the (estimated) junction temperature from logic 112. The logic 314 determines the present life and whether the present life is below a predefined threshold. In other embodiments, the logic 112 sends the data representative of the current, data representative of the voltage drop, and data representative of the temperature (ambient, and / o TSP) to the logic 314 that computes the junction temperature, degradation rate, and present life, which can be output on user interface 316.

[0057] In an example embodiment, the controller 304 is operable to output a notification upon determining that the aging status of the light emitting diode 102 is less than a predefined threshold. For example, certain regulatory environments may require LED 102 to be replaced when its remaining life is less than 80% or 70%. In particular embodiments, the controller can be configured to provide other types of notifications such as SMS (short messaging service) and / or email to predefined destinations.

[0058] The illustrated example shows a single light fixture 302. However, those skilled in the art should appreciate that this is merely for ease of illustration and an airfield lighting system can have any number of physically realizable number of airfield lighting fixtures 302. Moreover, in particular embodiments not all of the lighting fixtures present in an airfield lighting system are configured to operate light fixture 302.

[0059] In view of the foregoing structural and functional features described above, a methodology 400 in accordance with an example embodiment will be better appreciated with reference to FIG. 4. While, for purposes of simplicity of explanation, the methodology 400 of FIG. is shown and described as executing serially, it is to be understood and appreciated that the example embodiment is not limited by the illustrated order, as some aspects could occur in different orders and / or concurrently with other aspects from that shown and described herein. Moreover, not all illustrated features may be required in some example embodiments. The methodology 400 described herein is suitably adapted to be implemented in logic, such as hardware, software stored on a computer readable medium when executed by a processor, or a combination thereof.

[0060] At 402, data representative of a voltage drop across a light emitting diode ora string of light emitting diodes is obtained. For a single LED, the voltage drop is the difference between the voltages at the anode and the cathode of the LED. For a string of LEDs, the voltage drop is determines as the difference between the voltage at the anode of the first LED in the string and the cathode at the last LED in the string, divided by the number of LEDs in the string.

[0061] At 404, data representative of a current passing through the light emitting diode, or string of LEDs, is obtained. Although the measured current can also be employed, in example embodiments described herein the set point for the power supply can be employed. Using the set point eliminates the need for a current measuring device and thus can reduce the costs and complexity of a system employing this method.

[0062] At 406, the power consumed by the light emitting diode, or a light emitting diode in a string of LEDs, is determined based on the data representative of a voltage drop and the data representative of the LED current.

[0063] At 408, obtaining data presentative of a temperature at a point on the printed circuit board referred to herein as the Temperature Solder Point. The temperature solder point is the at the area where the LED meets the PCB. In an example embodiment, the temperature is measured within X of the temperature solder point. In an example embodiment, the temperature is obtained from the copper pour within X of the temperature solder point.

[0064] At 410, a junction temperature for the LED is determined based on the data representative of the temperature at the soldering point, a thermal resistance of the light emitting diode, and the power consumed by the LED. In an example embodiment, this is determined as TJ = TSP + (Rth j-sp x P), where Rthj-sp is the thermal resistance from TSP to the LED junction. Rth j-sp is found in the data sheet of the LED and represents the thermal performance of the LED. However, any suitable method for determining the junction temperature can be employed.

[0065] At 412, a degradation rate (D) is determined based on the junction temperature. In an example embodiment, the degradation rate is determined by D = A * exp(-Ea / (k * TJ)), where D is the degradation rate, A is a constant (e.g., a pre-exponential factor that can be determined by the datasheet for the LED or by experimentation), Ea is the activation energy (determined by the LED datasheet or by experimentation), k is the Boltzmann constant, and TJ is the LED junction temperature. In some embodiments, the A and Ea variables can be affected by other environmental factors besides temperature (e.g., vibration, humidity) and these inputs can be monitored and adjusted in real time. Additionally, there are some equations from manufacturers that can be used for determining A and Ea.

[0066] At 414, the present life of the LED is determined based on the degradation rate. In an example embodiment, the degradation rate and present life are calculated whenever the LED is switched on. These calculations can be updated at periodic or aperiodic intervals and / or can be triggered by changes in environmental conditions such as changes in the ambient temperature.

[0067] In an example embodiment, upon determining the degradation rate and / or present life, data representative of the degradation rate, present life, or both the degradation rate and present life are sent to a remote computing device. In particular embodiments, a notification is sent to the remote computing device responsive to determining the present life is less than a predefined threshold. For example, the predefined threshold can be the L70 or L80 rating (70%, 80% respectively).

[0068] Figure 5 is a block diagram that illustrates a computer system 500 upon which an example embodiment may be implemented. Computer system 500 can be employed to implement the logic 112 described in FIGS. 1-3 and / or the methodology 400 described in FIG. 4.

[0069] Computer system 500 includes a bus 502 or other communication mechanism for communicating information and a processor 504 coupled with bus 502 for processing information. Computer system 500 also includes a main memory 506, such as random access memory (RAM) or other dynamic storage device coupled to bus 502 for storing information and instructions to be executed by processor 504. Main memory 506 also may be used for storing a temporary variable or other intermediate information during execution of instructions to be executed by processor 504. Computer system 500 further includes a read only memory (ROM) 508 or other staticstorage device coupled to bus 502 for storing static information and instructions for processor 504. A storage device 510, such as a magnetic disk or optical disk, is provided and coupled to bus 502 for storing information and instructions.

[0070] An aspect of an example embodiment is related to the use of computer system 500 for Real-Time Monitoring of Light Emitting Diode (LED) life. According to one embodiment, Real-Time Monitoring of Light Emitting Diode (LED) life is provided by computer system 500 in response to processor 504 executing one or more sequences of one or more instructions contained in main memory 506. Such instructions may be read into main memory 506 from another computer-readable medium, such as storage device 510. Execution of the sequence of instructions contained in main memory 506 causes processor 504 to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory 506. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement an example embodiment. Thus, embodiments described herein are not limited to any specific combination of hardware circuitry and software.

[0071] The term "computer-readable medium" as used herein refers to any medium that participates in providing instructions to processor 704 for execution. Such a medium may take many forms, including but not limited to non-volatile media. Nonvolatile media include for example optical or magnetic disks, such as storage device 710. Common forms of computer-readable media include for example RAM, PROM, EPROM, FLASHPROM, CD, DVD, SSD or any other memory chip or cartridge, or other medium from which a computer can read.

[0072] Computer system 500 also includes a communication interface 518 coupled to bus 502. Communication interface 518 provides a two-way data communication coupling to a network link 520 that is connected to a local network 522. For example, communication interface 518 may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface 518 may be a localarea network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface 518 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information. Powerline communications is another form of communication that can be employed.

[0073] Network link 520 typically provides data communication through one or more networks to other data devices. For example, network link 520 may provide a connection through local network 522 to a host computer 524 (for example controller 304 in FIG. 3) or to data equipment operated by an Internet Service Provider (ISP) 526. ISP 526 in turn provides data communications through the worldwide packet data communication network, now commonly referred to as the "Internet" 528 that can be employed to communicate with server 530 (for example a controller or data repository at a remote location). Local networks 522 and Internet 528 both use electrical, electromagnetic, or optical signals that carry the digital data to and from computer system 500, are exemplary forms of carrier waves transporting the information.

[0074] The communication interface 518 enables computer system 500 to communicate with other external computing devices to receive commands, such as for operating a LED light and / or sending data to a remote computing device such as LED life and / or degradation rate. For example, the commands can include, but are not limited to, turning the LED on or off, intensity, and blink rate.

[0075] Described above are example embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies, but one of ordinary skill in the art will recognize that many further combinations and permutations of the example embodiments are possible. Accordingly, this application is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.

Claims

CLAIMS1. A method, comprising: obtaining, by an airfield lighting controller, data representative of at least one operating condition for a light emitting diode of an airfield lighting fixture that is located remotely from the airfield lighting controller; determining, by the airfield lighting controller, a current aging status for the light emitting diode based on the data representative of the at least one operating condition; and outputting, by the controller, on a user interface, data representative of the aging status for the light emitting diode.

2. The method according to claim 1 , wherein the data representative of the at least one operating condition is provided in real-time.

3. The method according to claim 1 , wherein the data representative of the at least one operating condition is sent by the airfield light fixture to the airfield lighting controller via one of a group consisting of a powerline communication, and a wireless communication, a signal line communication.

4. The method according to claim 1 , further comprising outputting by the controller a notification upon determining that the aging status of the light emitting diode is less than a predefined threshold.

5. The method of claim 4, wherein the predefined threshold is one of a group consisting of seventy percent of remaining life and eighty percent of remaining life.

6. The method according to claim 1 , further comprising:the data representative of the at least one operating condition comprises data representative of a voltage drop across a light emitting diode; the data representative of the at least one operating condition comprises data representative of a current passing through the light emitting diode; the data representative of the at least one operating condition data representative of a temperature of the light emitting diode;; determining aging status comprises: determining the power consumed by the light emitting diode based on the data representative of the voltage drop across the light emitting diode and the data representative of the current passing through the light emitting diode; determining a junction temperature for the light emitting diode based on the data representative of the temperature, a thermal resistance of the light emitting diode, and the power consumed by the light emitting diode; determining a degradation rate based on the junction temperature; and determining a present life of the light emitting diode based on the degradation rate.

7. The method according to claim 6, wherein the data representative of the current is a commanded set current.

8. The method according to claim 6, wherein the data representative of the current passing through the diode is a command current and not a direct measurement of the current passing through the light emitting diode.

9. An airfield lighting fixture, comprising: a printed circuit board; a light emitting diode coupled with the printed circuit board;a communication interface; light fixture logic coupled with the light emitting diode and the communication interface; the light fixture logic is operable to obtain data representative of at least one operating condition for the light emitting diode; the light fixture logic is operable to determine a current aging status for the light emitting diode based on the data representative of the at least one operating condition; and the light fixture logic is operable to send data representative of aging status to an airfield lighting controller that is located remotely from the airfield lighting fixture.

10. The airfield lighting fixture according to claim 9, wherein the data representative of the aging status is provided in real-time.11 . The airfield lighting fixture according to claim 9, wherein the data representative of the aging status is sent by the airfield light fixture to the airfield lighting controller via one of a group consisting of a powerline communication, and a wireless communication, a signal line communication.

12. The airfield lighting fixture according to claim 9, further comprising sending a notification upon determining that the aging status of the light emitting diode is less than a predefined threshold.

13. The airfield lighting fixture of claim 12, wherein the predefined threshold is one of a group consisting of seventy percent of remaining life and eighty percent of remaining life.

14. The airfield lighting fixture according to claim 9, further comprising:a temperature sensor for sensing the temperature at a soldering point where the light emitting diode is coupled with the printed circuit board; a voltage sensor for sensing a voltage drop across the light emitting diode; the light fixture logic is coupled with the temperature sensor and the voltage sensor; the light fixture logic is operable to obtain data representative of a voltage drop from the voltage sensor; the light fixture logic is operable to obtain data representative of a current passing through the light emitting diode; the light fixture logic is operable to determine the power consumed by the light emitting diode based on the data representative of a voltage drop across the light emitting diode and the data representative of a current passing through the light emitting diode; the light fixture logic is operable to determine a junction temperature for the light emitting diode based on the data representative of the temperature at the soldering point, a thermal resistance of the light emitting diode, and the power consumed by the light emitting diode; the light fixture logic is operable to determine a degradation rate based on the junction temperature; and the light fixture logic is operable to determine a present life of the light emitting diode based on the degradation rate.

15. The apparatus according to claim 14, further comprising: the light emitting diode comprises a string of light emitting diodes with at least two light emitting diodes having a first light emitting diode and a last light emitting diode; the voltage sensor is operable to obtain data representative of a voltage at the anodeof the first light emitting diode and data representative of a voltage at the cathode of the of the last emitting diode; and the light fixture logic determines the data representative of the voltage drop based on the data representative of voltage at the anode of the first light emitting diode and data representative of the voltage at the cathode at the last light emitting diode divided by a number of light emitting diode in the strings.

16. The apparatus set forth in claim 14, wherein the data representative of the current is a commanded set current for operating the string of light emitting diodes.

17. The apparatus set forth in claim 16, wherein the temperature sensor is within ten millimeters of the soldering point.

18. The apparatus set forth in claim 14, the printed circuit board further comprising a copper pour, wherein the soldering point is coupled with a copper pour and temperature sensor coupled with the copper pour within ten millimeters of the soldering point.

19. The apparatus set forth in claim 16, the light fixture logic is further operable to send data representative of the degradation rate and data representative of the present life to a remote computing system.

20. The apparatus set forth in claim , the light fixture logic is further operable to send a notification responsive to the present life is less than a predefined threshold.

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