Abstract:
Disclosed is a method of determining depreciation of a lumen output of an LED. More particularly, disclosed is a method of determining depreciation of a lumen output of an LED comprising monitoring, by a processing device, an operating characteristic of an AC power source operatively coupled to the LED; determining, by the processing device, whether a lumen output the LED depreciated beyond a specified lumen value based on the monitoring; and causing, by the processing device, an indicator to provide notification to a user based on determining the lumen output of the LED depreciated beyond the specified lumen value.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 61/790,847, filed Mar. 15, 2013, the entire disclosure of which is expressly incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This present disclosure generally relates to underwater lighting systems, and more particularly for lighting systems for use in swimming pools, spas and the like, which provide an indication to a user indicating that at least one of the lights in a lighting system may need to be replaced. 
         [0004]    2. Background of the Invention 
         [0005]    In-ground swimming pools and spas are often installed with lights, typically in a horizontal row a short distance below the waterline. The underwater lighting has a pleasing visual effect and permits safe swimming during nighttime. 
         [0006]    Commercial pools in most jurisdictions throughout the country and residential pools in some cities or counties have minimum illumination requirements, typically set and enforced by health departments and local building codes, to provide for safe pool use. 
         [0007]    Assuming that a specified pool light delivers predictable illumination, in lumen output, pools are designed with the number of lights and niches required to deliver at or above the required illumination, in lumens, for the square footage of the pool surface area. Pools historically have been illuminated with submersible incandescent lights which deliver relatively constant lumen output throughout the life of the incandescent bulb. A typical incandescent bulb has some lumen depreciation in its first 100 hours of use and then maintains a steady state lumen output until the end of its life. Thus, as long as the incandescent bulb is emitting light, the incandescent bulb is emitting the prescribed amount of light. 
         [0008]    In contrast, the lumens emitted by LEDs and submersible LED light fixtures depreciate appreciably and predictably over the life of the LEDs. This gradual depreciation over the life of an LED, however, gives no indication as to when the LED will stop delivering a minimum prescribed lumen output for safe illumination of a pool. It is desirable therefore to provide an indication that an LED output has depreciated below a minimum lumen output level. 
       SUMMARY OF THE INVENTION 
       [0009]    Exemplary embodiments of the present disclosure relate to monitoring an operation of LEDs in a light fixture to determine whether the lumen output of the LEDs has depreciated by a specified amount and to provide a user with an indicator to notify the user that the LEDs or the light fixture should be replaced. In exemplary embodiments, a determination that a light fixture or LEDs of the light fixture should be replaced can be based on a total time of operation of the LEDs. A total time of operation or its equivalent can be determined, for example, based on tracking zero-crossing events of an AC power source when the LEDs are energized. 
         [0010]    In one embodiment, a method of determining depreciation of a lumen output of an LED assembly is disclosed. The method includes monitoring an operating characteristic associated with an AC power source operatively coupled to the LED assembly and determining whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified lumen value based on the operating characteristic of the AC power source. 
         [0011]    In another embodiment, a system for determining depreciation of a lumen output of an LED assembly is disclosed that includes a circuit to monitor an operating characteristic associated with an AC power source operatively coupled to the LED assembly, a non-transitory computer readable storing executable instruction, and a processing device programmed to execute the executable instructions to monitor an operating characteristic associated with an AC power source operatively coupled to the LED assembly and determine whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified lumen value based on the operating characteristic of the AC power source. 
         [0012]    In yet another embodiment, an apparatus is disclosed that includes a housing, an LED disposed within the housing, and circuitry disposed within the housing. The circuitry is operatively coupled to the LED and to an AC power source and is configured to monitor an operating characteristic associated with AC power source operatively coupled to the LED assembly and determine whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified lumen value based on the operating characteristic of the AC power source. 
         [0013]    In still another embodiment, a non-transitory computer-readable medium storing instruction that are executable by a processing device is disclosed. Execution of the instructions by the processing device cause the processing device to implement a method for determining depreciation of a lumen output of an LED assembly. The method implemented upon execution of the instructions by the processing device includes monitoring an operating characteristic associated with an AC power source operatively coupled to the LED assembly and determining whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified lumen value based on the operating characteristic of the AC power source. 
         [0014]    In some embodiments, the operating characteristic of the AC power source can be determined by detecting a zero crossing event of an AC voltage signal provided by the AC power source. 
         [0015]    In some embodiments, determining whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified value can include determining a number of zero crossing events occurring when the LED is energized. 
         [0016]    In some embodiments, a counter can be implemented to track a number of zero crossing events and the counter can be incremented in response to detection of a zero crossing event. 
         [0017]    In some embodiments, a counter value of the counter can be compared to a threshold value and an indicator that the threshold value has been exceeded can be provided. 
         [0018]    In some embodiments, the counter value of the counter can be multiplied by half of a period of the AC voltage signal to compute a total time of operation, the total time of operation can be compared to a threshold value, and an indicator that the threshold value has been exceeded can be provided. 
         [0019]    In some embodiments, a zero crossing detection circuit can be used to detect a zero crossing event associated with the AC power source. 
         [0020]    In some embodiments, the processing device can determine whether a lumen output of an LED associated with the LED assembly depreciated beyond a specified value by determining a number of zero crossing events occurring when the LED is energized. 
         [0021]    In some embodiments, the processing device can be programmed to implement a counter to track a number of zero crossing events and to increment the counter in response to detection of a zero crossing event. 
         [0022]    In some embodiments, the processing device is programmed to compare a counter value of the counter to a threshold value and provide an indicator that the threshold value has been exceeded. 
         [0023]    In some embodiments, the processing device is programmed to multiply the counter value of the counter by half of a period of the AC voltage signal to compute a total time of operation, compare the total time of operation to a threshold value, and provide an indicator that the threshold value has been exceeded. 
         [0024]    Any combination or permutation of embodiments is envisioned. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    Important features of the present invention will be apparent from the following Detailed Description of the Invention, taken in connection with the accompanying drawings, in which: 
           [0026]      FIG. 1  shows an exemplary light fixture including LED lights and a replacement indicator; 
           [0027]      FIG. 2  is a block diagram showing components of an exemplary circuit configured to implement the replacement indicator; 
           [0028]      FIGS. 3-4  are flowcharts of processing steps carried out by the system for monitoring when an LED light should be replaced; and 
           [0029]      FIGS. 5A-5B  are schematic representations of pool lighting systems including light fixtures and circuitry for implementing replacement indicators. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]      FIG. 1  shows an exemplary light fixture including LED lights and a replacement indicator. The light (or luminaire) fixture  10  includes a housing  16  and one or more light emitting diodes (LEDs)  12  as a light source, and is adapted to be submersed underwater for providing underwater illumination. The light fixture  10  can employ different color LEDs  12  (e.g. red, green, blue, and white LEDs) and can be adapted to generate a variety of different colors, including white light. Desired colors can be obtained by powering various combinations of the LEDs of different primary colors. In some embodiments, a single LED that changes colors can be employed. 
         [0031]    In some embodiments, the light fixture  10  can include a replacement indicator  14  for providing a visual indication as to the status of the LEDs  12  (e.g. lumen output level, hours of operation, time to change light). The replacement indicator  14  can be located on the housing  16  or within the housing  16 . Depending on the status of the lumen output, the replacement indicator  14  can employ a particular color output out of a plurality of different color outputs. The status of the lumen output can be determine based on a total time (e.g., milliseconds, seconds, minutes, hours, etc.) of operation of the light fixture (e.g., a total amount of time that the LEDs  12  have been on since being installed). For example, the replacement indicator  14  could provide a green color light when the total time of operation is below a minimum threshold level, and the replacement indicator  14  could provide a red color light when the total time of operation exceeds the minimum threshold (e.g., to indicate that the light fixture  10  is due for replacement). In addition or as an alternative to the visual indication, the replacement indicator  14  could comprise an audible indication to alert a user of a need to replace the light fixture  10 . 
         [0032]    The LEDs  12  themselves can provide a visual status indicator. For example, in response to determining that the LEDs  12  should be replaced (e.g., based on determining that the total time of operation exceeds a threshold level), the LEDs  12  can blink (e.g., turn off and on) for a specified period of time when the LEDs  12  are first turned on and/or can periodically blink (e.g., turn off and on) at a specified time interval while the LEDs  12  are in operation. A visual status indicator can be provide through a combination of the LEDs  12  and replacement indicator  14 . 
         [0033]      FIG. 2  is a block diagram showing components of an exemplary circuit configured to implement the replacement indicator;. The circuit  20  can be incorporated into the housing of the light fixture  10 . Portions of the circuit  20  can be external to the light fixture  10 . The circuit  20  includes the LEDs  12 , LED drivers  22 , a processing device  26  (e.g., a microprocessor, controller, microcontroller, etc.), memory  28  (e.g., one or more non-transitory computer-readable media storage devices), a power supply  30 , and a zero cross detection circuit  32 . 
         [0034]    The LEDs  12  can be operatively coupled to the processing device  26  via one or more LED drivers  22 , which are operative to turn the LEDs  12  on or off in response to an output of the processing device  26 . The power supply  30  can be configured to receive AC voltage from an AC power source  24  (e.g., a 120V or 240V AC signal having a frequency of 60 Hz) and to convert the AC voltage signal to a DC voltage, which can be fed to the processing device  26  to power the processing device  26 . 
         [0035]    The processing device  26  can also be operatively coupled to the memory  28 , which can store firmware  34  that can be executed by the processing device  26  to control an operation of the circuit  20 . The firmware  34  can include executable code and/or instructions for implementing a replacement indicator program to determine when at least one of the LEDs  12  should be replaced, as described in more detail below. The firmware  34  can also include executable code and/or instructions for controlling a normal operation of the LEDs  12 . 
         [0036]    The zero crossing detection circuit  32  can be operatively coupled between the AC power source  24  and the processing device  26 . The zero crossing detection circuit  32  can receive AC voltage from the power source  24  and can be configured to determine each time the AC voltage signal crosses zero voltages. In response to detecting that a zero crossing event has occurred (i.e., the AC voltage signal transitioned from a negative voltage to a positive voltage or vice versa), the zero crossing detection circuit  32  can output a zero crossing detection signal to the processing device  26 . The zero crossing detection signal can be implemented as a digital binary signal that is high (e.g., ‘1’) in response to detection of a zero crossing and is otherwise low (e.g., ‘0’), or vice versa. Those skilled in the art will recognize that the zero crossing detection signal can take on any of several forms. 
         [0037]    Since the AC voltage signal is periodic (e.g., having an operating frequency of 60 Hz), the zero cross detection circuit  32  can detect a zero crossing event twice for each period of the AC voltage signal approximately. For example, for an AC voltage signal operating at 60 HZ, the zero detection circuit  32  can detect a zero crossing approximately every 8.33 milliseconds (every half period of the sinewave). By detecting zero crossing events, the present disclosure can advantageously determine an amount of time the LEDs  12  are energized (e.g., turned ‘on’) or de-energized (e.g., turned ‘off’), for example, by tracking the number of zero crossings detected by the zero crossing detection circuit  32 , and by monitoring whether the LEDs  12  are ‘on’ or ‘off’, as described in more detail below. 
         [0038]    Those skilled in the art will recognize that the zero crossing detection circuit  32  can directly process voltage from the AC power source  24  and/or can process a signal that corresponds to and/or is associated with the voltage from the AC power source  24 . For example, the power supply  30  can provide the zero crossing detection circuit  32  with a conditioned power signal, which the zero crossing detection circuit  32  can use to detect zero crossing events associated with the AC voltage signal provided by the AC power source. For example, the zero crossing detection circuit  32  can receive a reduced voltage signal (a voltage signal having amplitude of 3 volts, 5 volts, 6 volts, etc.) corresponding to the AC voltage signal, which can have an amplitude of, for example, 120 volts or 240 volts. 
         [0039]    As discussed above, the processing device  26  can be configured to control an operation of the LEDs  12  and/or the replacement indicator  14 . For example, the processing device  26  can control an operation of the LEDs  12  and/or the replacement indicator  14  according to the firmware  34  stored in the memory  28  and/or according to one or more control signals received from a remote controller or a control system. Portions of the circuit  20  can be implemented as part of the remote controller or control system. 
         [0040]    The processing device  26  can execute the firmware  34  to monitor the output of the zero crossing detection circuit  32  (e.g., the zero crossing detection signal) when the LEDs  12  are operating (e.g., turned on). Conversely, when the LEDs  12  are not operating (e.g., turned off) the processing device  26  can be programmed (e.g., according to the firmware  34 ) to ignore the zero detection output signal provided by the zero crossing detection circuit. In some embodiments, the processing device  26  can be programmed (e.g., according to the firmware  34 ) to monitor the output of the zero crossing detection circuit  32  when the LEDs  12  are both operating and are not operating. 
         [0041]    The processing device  26  can be programmed (e.g., according to the firmware  34 ) to implement a counter to track a number of zero crossings detected by the zero crossing detection circuit. In one embodiment, the processing device  26  can be programmed to increment the counter when the LEDs  12  are turned on for each zero crossing event detected by the zero crossing detection circuit  32 , for every other zero crossing event detected, and/or after a specified number of zero crossing events have occurred since the last time the counter was incremented. Using the counter value maintained by the counter, the processing device  26  can be programmed to determine a total amount of time that the LEDs  12  have been ‘on’ since the LEDs  12  and/or the light fixture  10  were installed. 
         [0042]    The processing device  26  can be programmed to multiply the counter value by a stored value corresponding to the time period between incrementing the counter. For example, the counter can be incremented every time a zero crossing is detected when the LEDs  12  are ‘on’, and the processing device  26  can multiply the counter value by half the period of the AC voltage signal to obtain a total time (e.g., milliseconds, seconds, minutes, hours, etc.) of operation of the LEDs  12 . As another example, the counter can be incremented every other time a zero crossing is detected when the LEDs  12  are ‘on’, the processing device  26  can multiply the counter value by the period of the AC voltage signal to obtain a total time of operation of the LEDs  12 . 
         [0043]    The processing device  26  can compare the counter value and/or a total time of operation to a threshold value. The threshold value can correspond to a counter value and/or a quantity of time that correlates to an estimated percent depreciation of the lumen output from the LEDs  12 , for example, an estimated percentage depreciation for which the lumen output is no longer acceptable (e.g., does not satisfy jurisdictional requirements). In exemplary embodiments, lumen output of the LEDs  12  can be predictable over the life of the LEDs  12  such that the total time of operation (or the counter value itself) can be correlated to the lumen out of the LEDs  12 . The threshold value can be a fixed value or can be adjustable (e.g., by the user or the processing device  26 ). 
         [0044]    In response to determining that the counter value and/or the total time of operation of the LEDs  12  exceed the threshold value, the processing device  26  can be programmed (e.g., according to the firmware  34 ) to implement one or more indicators that indicate the LEDs  12  should be replaced. For example, the processing device  26  can control the output of the replacement indicator  14  (e.g., cause the replacement indicator  14  to output a red light) and/or can control the operation of the LEDs  12  (e.g., cause the LEDs  12  to blink). 
         [0045]      FIG. 3  is a flowchart showing processing steps carried out by the system for monitoring when an LED light should be replaced The firmware  34  can include code and/or instructions, and the processing device  26  can execute the code and/or instructions to carry out a light replacement indicator process  300  as shown in  FIG. 3 . In step  305 , when power is applied to light fixture  10 , the processing device  26  monitors a parameter associated with operation of the LEDs  12 . The parameter monitored can be, for example, total time of operation of the LEDs  12 , which can be used to determine an amount of lumen output depreciation of the LEDs  12 , as described herein. In step  310 , microprocessor  26  determines if the parameter monitored exceeds a threshold level. As an example, the threshold level can be a specified total time of operation corresponding to a predetermined lumen depreciation of the LEDs  12 . If the threshold is not exceeded, the processing device  26  continues to monitor the parameter. If the threshold is exceeded, the processing device  26  initiates a perceptible indicator that indicates the parameter exceeds the threshold level. The threshold level can be user adjustable, predetermined, etc., depending on the application and parameter measured. 
         [0046]      FIG. 4  is another flowchart showing processing steps carried out by the system for monitoring when an LED light should be replaced. The firmware  34  can include code and/or instructions, and the processing device  26  can execute the code and/or instructions to carry out a light replacement indicator process  400  as shown in  FIG. 4 . In step  402 , the processing device  26  can monitor for zero crossing events based on a zero crossing detection signal received from the zero crossing detection circuit  32 . When a zero crossing event is detected, the processing device  26  can determine whether the LEDs are ‘on’ or ‘off’ at step  404 . If the LEDs  12  are ‘off’, then in step  406 , the processing device  26  can ignore the zero crossing event and can continue to monitor for zero crossing events. If the LEDs  12  are ‘on’, then in step  408 , the processing device  26  can increment a counter. In step  410 , in response to the detection of a zero crossing event at step  408 , the processing device  26  can compare the counter value or time value corresponding to the counter value to a threshold value. In step  412 , the processing device  26  determines whether the counter value or the time value exceeds a threshold value. If, in step  412 , the processing device  26  determines the counter value or the time value does not exceed the threshold value, then the processing device  26  returns to step  402  and can continue monitoring for zero crossing events. If, in step  412 , the processing device  26  determines the counter value or time value exceeds the threshold value, then in step  414  the processing device  26  can provide a perceptible indicator that indicates the parameter exceeds the threshold level and that the LED fixture  10  or LEDs  12  should be replaced. 
         [0047]      FIGS. 5A-5B  are schematic representations of pool lighting systems including light fixtures and circuitry for implementing replacement indicators.  FIGS. 5A-5B  each shows an exemplary pool lighting system  500  including light fixtures  10  disposed in a swimming pool  502  below the water line. The pool lighting system  500  can be part of a pool or home automation system and/or can be a stand-alone system. The light fixtures  10  can include the circuit  20 , which can communicate with a remote or central control system  504 , which can operate to control the pool lighting system  500  as well as other systems (e.g., fluid circulation system of the pool, other lighting systems, etc.). For example, the control system  504  can provide one or more signals to the circuit  20  (e.g., from the processing device  26 ) of the light fixtures  10  and/or can receive one or more signals from the circuit  20  (e.g., the processing device  26 ) of the light fixture  10 . The signals sent to the light fixture can include commands, messages, and/or instruction that can be used by the circuit  20  to determine when to energize the LEDs of each fixture  10  and when to de-energize the LEDs of each fixture  10 . Each fixture can be independently controllable by their respective circuit and/or can be controlled collectively. The circuits  20  of the fixtures  10  can be programmed to communicate with the control system  504  using wired or wireless communication. 
         [0048]    The lighting system  500  can include an alarm  508  that can be controlled by each of the circuits  20  and/or by the control system  504 . For example, the circuit  20  can send a signal to the alarm when an unacceptable lumen depreciation has been identified and the alarm can generate a visual and/or audible alarm (e.g., lights and/or sound) to notify the user that one of the fixtures  10  or LEDs within the fixtures  10  should be replaced (see, e.g.,  FIG. 5A ). As another example, the circuit  20  can communicate with the control system  504  to notify the control system  504  that an unacceptable lumen depreciation has been identified and the control system  504  can activate the alarm system  508  (see, e.g.,  FIG. 5B ). The alarm system  508  can indicate which of the fixtures  10  caused the alarm. As described above, each fixture  10  can also provide notification to the user that an unacceptable lumen depreciation has been identified (e.g., using the replacement indicator  14  and/or by blinking the LEDS according to a specified pattern). 
         [0049]    While the circuit  20  has been described as being incorporated in to the fixture  10  in  FIGS. 5A-5B , those skilled in the art will recognize that portions of the circuit may be external of the fixture  10  and/or may be incorporated into the control system  504 . Furthermore, while the alarm system  508  is shown as being separate from the control system  504 , those skilled in the art will recognize that the alarm system  508  can be incorporated into the control system  504 . 
         [0050]    While exemplary embodiments have been described with respect to incrementing a counter and exceeding a threshold value, those skilled in the art will recognize that exemplary embodiments of the present disclosure can be implemented to decrease a counter and/or determine whether the counter value or corresponding time value is at or below the threshold. For example, the counter can be set to an initial value and can be decremented each time a zero crossing event is detected when the LEDs  12  are ‘on’. When the counter value reaches zero, the processing device  26  can be programmed to provide a perceptible indicator that the parameter exceeds the threshold level and that the LED fixture  10  or LEDs  12  should be replaced. 
         [0051]    Having thus described the system and method in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. It will be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure. What is desired to be protected by Letters Patent is set forth in the following claims.