WO2014121367A1

WO2014121367A1 - Measurement and control of an outdoor light fixture

Info

Publication number: WO2014121367A1
Application number: PCT/CA2013/000117
Authority: WO
Inventors: Simon H. Lightbody; Ken CARTMILL; Matthew Francis Durdle; Tristan Roland Laan; Jeffrey David HIBBS; Gregory P. Jacklin
Original assignee: LED Roadway Lighting Ltd
Current assignee: LED Roadway Lighting Ltd
Priority date: 2013-02-05
Filing date: 2013-02-05
Publication date: 2014-08-14
Anticipated expiration: 2015-08-05
Also published as: WO2014121367A8

Abstract

An outdoor light fixture having a lamp sensor and a management server is provided. The lamp sensor is utilized for assessing depreciation of light output of a light emitting diode (LED) light engine of the outdoor LED light fixture. Collected data can be sent to a management server for analysis to determine life expectancy of the light fixture and also determine power levels. The power levels may be applied to the light fixture to maintain a constant lumen output or lower output to meet life expectancy requirements. The performance of the outdoor light fixture having the lamp sensor may be utilized to gauge the performance of similar outdoor light fixtures without lamp sensors.

Description

MEASUREMENT AND CONTROL OF AN OUTDOOR LIGHT FIXTURE

TECHNICAL FIELD

The present disclosure relates to lighting fixtures and more specifically to determining depreciation and controlling light emitting diode (LED) outdoor light fixtures.

BACKGROUND

Light emitting diodes (LEDs) have become popular for a variety of lighting applications, such as outdoor area lighting, because of high efficiency, light quality and controllability. Challenges still exist, however, with regards to maintaining light output over the lifetime of the light fixtures and the life expectancy itself. LEDs may depreciate in light output over time, thus becoming dimmer based upon the current applied to the LEDs and environmental conditions to which the light fixtures are exposed. In outdoor lighting applications such as, for example, area lighting for parking lots, parking garages, building exteriors, or roadways, the amount of light being produced by an outdoor light fixture can be important in terms of public safety, liability, deployment strategy and maintenance costs. The ability to determine when the light engine of a light fixture is not producing, or will not produce, sufficient light, or predict when it may fail, is useful in determining when the light engine or luminaire will need to be replaced, thus minimizing maintenance costs.

Accordingly, it is desirable to be able to determine the depreciation of the light output of outdoor lighting fixtures and to provide the ability to control the output of a light fixture in response to depreciation levels.

SUMMARY

In accordance with an aspect of the present disclosure there is provided an outdoor light fixture comprising a light engine positioned within a housing of the outdoor light fixture, the light engine including a plurality of light emitting diode (LED) light sources and a lens module having a plurality of optical elements for each of the plurality of LED light sources; a lamp sensor positioned within a housing of the light fixture, the lamp sensor directed towards a transparent pane covering the lens module to receive light from the light engine reflected by the transparent pane; and a processor configured to determine a characteristic from the lamp sensor and store the characteristic to non-volatile memory with an associated timestamp.

In accordance with another aspect of the present disclosure there is provided a method for management of an outdoor light fixture. The method comprises receiving at a management server data from an outdoor light fixture representing a lamp sensor characteristic from a lamp sensor for sensing light output from a light engine having a plurality of light emitting diode (LED) light sources of the outdoor light fixture; determining at the management server a depreciation rate of the light engine based upon the received lamp sensor characteristic; and sending a parameter from the management server to the outdoor light fixture in response to the determined depreciation rate to adjust the light output of the light engine of the outdoor light fixture.

In accordance with yet another aspect of the present disclosure there is provided a system for management of a plurality of outdoor light fixtures. The system comprises an outdoor light fixture and a management server. The outdoor light fixture for determining a lamp sensor characteristic from a lamp sensor positioned within a housing of the outdoor light fixture receiving light from a light engine including a plurality of light emitting diode (LED) light sources; and storing the lamp sensor characteristic to non-volatile memory with an associated timestamp. The management server for receiving data from the outdoor light fixture include the lamp sensor characteristic and the associated time stamp; determining a depreciation rate of the light engine based upon the received lamp sensor characteristic; and sending a parameter to the outdoor light fixture in response to the determined depreciation rate to adjust the output of the light engine.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the disclosure will become more apparent from the following description in which reference is made to the appended drawings wherein:

Figure 1 is a top perspective view of an outdoor light fixture;

Figure 2 is a bottom perspective view of the outdoor light fixture;

Figure 3 is a partial bottom view of the outdoor light fixture having a lamp sensor;

Figure 4 is a cross-section view along a width of the outdoor light fixture looking towards the lamp sensor;

Figure 5 is partial perspective bottom view of the outdoor light fixture;

Figure 6 is another partial bottom view of the outdoor light fixture, when the bottom door with the transparent pane is open;

Figure 7 is a side view of the outdoor light fixture and its bottom door is open;

Figure 8 is a partial cross-section side view along a length of a front section of the outdoor light fixture; Figure 9 is a partial cross-section side view along a length of the front section of the outdoor light fixture for illustrating the operation of the lamp sensor;

Figure 10 is a block diagram illustrating a management server and outdoor light fixtures which communicate via a wireless network;

Figure 11 is a flow diagram of a method executed in the management server for determining depreciation and controlling outdoor light fixtures;

Figure 12 is a flow diagram of a method for assessing depreciation of an outdoor light fixture using a lamp sensor;

Figure 13 is another flow diagram of a method executed in the management server for determining depreciation and control outdoor light fixtures; and

Figure 14 is another flow diagram of a method for assessing depreciation of an outdoor light fixture using a lamp sensor and controlling the outdoor light fixture output.

DETAILED DESCRIPTION

Embodiments are described below by way of example only, with reference to Figures 1-14.

A lamp sensor for use in an outdoor light fixture is provided for determining a depreciation value of the light output of an LED light engine. The term outdoor light fixture is used to include fixtures for use in outdoor lighting applications, for example fixtures for illuminating roadways, parking lots or parking garage structures, canopies, tunnels, bridges, and sporting venues, etc. The output of an LED light engine in outdoor light fixtures can degrade over time due to environmental conditions, heating and cooling performance of the fixture, and characteristics of the particular LEDs and power supply. The lamp sensor enables a characteristic of the sensor, such as a sensor value, to be periodically obtained and sent to a management server for analysis. The performance of the outdoor light fixture may be determined by a depreciation value or lumen maintenance value, which can be correlated with environmental or operational factors with additional data that may be provided by the fixture that may impact the performance of the light fixture. The performance can be trended over extended periods of time to determine expected future output levels. The performance of the outdoor light fixture having the lamp sensor may be utilized to gauge the performance of similar outdoor light fixtures with or without lamp sensors, but are assumed to have similar performance characteristics based upon aspects such as the type of light fixture, the type of light engine, the type of lens, or the type of power supply in addition to geographic or environmental factors. Parameters can then be generated, and applied to the outdoor light fixture, or a group of outdoor light fixtures, for example a new power level to maintain a desired constant lumen output, or reduce output to meet life expectancy objectives. The lamp sensor is positioned within the housing of the outdoor light fixture angled towards a transparent pane of the light fixture below a light engine. The lamp sensor may be positioned relative to the light engine to capture light that would normally be wasted and therefore does not interfere with the normal operation of the outdoor light fixture. The lamp sensor receives reflected light proportional to the light falling on the ground below the fixture in order to determine the depreciation value, and does not interfere or waste any light output of the light engine. Since having a lamp sensor in every fixture adds cost and complexity, sensors may be implemented only in a subset of outdoor light fixtures to collect data to characterize the performance of multiple light fixtures having similar configuration and in similar operating environments. Outdoor light fixtures that experience the same conditions and have the same installation configuration may reasonably experience the same level of degradation in light output over time. Therefore, measuring the light degradation of one or more units, to determine compensation factors for a larger group, may be performed.

Referring to Figures 1 and 2, an outdoor light fixture 100 in which the lamp sensor can be used is shown. To aid in the description of the outdoor light fixture 100, a planar lighting fixture designed with a 'cobrahead' configuration, is disclosed. Although the lamp sensor is presented in the context of the planar fixture, the lamp sensor may be implemented in fixtures for other applications having different housing and light engine designs. It will be appreciated that the aspect of the outdoor light fixture disclosed will be applicable to other types of outdoor light fixtures. The outdoor light fixture 100 is designed for modularity, which allows for easy assembling and maintenance of the parts of the outdoor light fixture. The light engine 102 allows for quick, tool-less replacement of system components and is also designed to provide optics and thermal performance so that the light fixture 100 may be used for outdoor lighting applications. Referring to the bottom view of the light fixture in Figure 3, the light engine 102 includes a printed circuit board (PCB) 104 (shown in Figure 8) with any number of light sources and a lens module (refractor) 106. The lens module 106 includes a plurality of optical elements 108, each being allocated to the corresponding LED on the PCB 104. The PCB 104 and the lens module 106 are designed to ensure that they are mated together such that each optical element 108 is properly aligned with the corresponding LED. In the description below, the terms "light source" and "LED" are used interchangeably. In the description below, the terms "lens module", "lens" and "refractor" may be used interchangeably. The term "light engine system" may also be considered to include the power supply and the associated light engine.

The lens module 106 is covered by a bottom door 130 with a pane 132 made from a transparent material (e.g., glass cover or clear plastic). In a non-limiting example, the outdoor light fixture 100 is configured so that when installed, the transparent pane 132 is substantially perpendicular to the axis of maximum light output from the light sources and substantially parallel with the base surface of the lens module 106. In a non-limiting example, each optical element 108 is a symmetric multi-directional lens element comprising a front section 112 substantially acting as a refractive element or refractor and a backlight control section 1 14 having a Total Internal Reflection (TIR) structure acting as a reflective element or a reflector. The lens module 106 is installed in the light fixture 100 so that the TIR structure of the backlight control section maximizes the amount of light collected and directed towards a preferential side and minimizes the amount of light directed at the opposite side, or area behind the light fixture 100. In a non-limiting example, the preferential side of the TIR structure is directed towards a desired illumination area such as a roadway or street (e.g., roadway side or street side) which corresponds to the front section of the light fixture 100. The non-preferential side is behind the fixture or towards the back section typically providing the mounting or pole section of the light fixture.

In order to determine the depreciation of the light output of the light engine 102 the lamp sensor 150 is provided for measuring light intensity. The lamp sensor 150 may be positioned toward the preferential side of the optical elements to accurately sample the light output of the light engine 102. The lamp sensor 150 comprises a photo-sensor, a photo-detector, or any type of light detecting device that can provide a characteristic providing a representation of the detected light level from the light engine of the fixture such as defined by a sensor value. The characteristic provided by the lamp sensor 150 may be used as a value correlated to the luminous flux output provided by the light engine. In Figure 4, a cross-section view is shown along a width of the outdoor light fixture looking towards the lamp sensor 150. The lamp sensor 150 is angled towards the major horizontal plane of a transparent pane 132.

As shown in Figure 5 and 6, the lamp sensor 150 is installed to be releasable and is located in a housing of the outdoor light fixture by using a mounting bracket 154 in a forward portion of the light fixture in front of the light engine 102. In a non- limiting example, the bracket 154 is located near one edge of the housing near to a door latch 122. The bracket 154 may be formed so that the lamp sensor 150 is at an angle with respect to the transparent pane 132. The lamp sensor 150 may also include a temperature sensor (not shown) either in proximity with lamp sensor 150, in contact with the lamp sensor 150 or incorporated within the lamp sensor 150. The light fixture 100 may further comprise additional sensors (not shown) such as a temperature sensor on the PCB 104 for determining a temperature of the light engine 102, and/or an external temperature sensor for determining either the external temperature or a temperature of the light fixture 100. Additional sensors may also be provided to determine conditions of the operating environment such as but not limited to, ambient light sensor, humidity sensor, or supply voltages in addition to determining a noise value associated with a sensor.

Also referring to Figure 7, the top housing cover 120 has the door latch 122 for locking and unlocking a bottom housing cover 130. The hook (or tongue) in the latch 122 is engaged with a slot or recess formed in the bottom housing cover 130. By pulling down the latch 122, the latch 122 is released from the bottom housing cover 130. The outdoor light fixture 100 can engage with a pole through a pole mounting section 138 of the top housing 120.

The housing may also provide cooling fins 140 and a receptacle 142 for receiving accessories such as a photo-sensor, a global positioning system (GPS) receiver, a wireless control interface and may also house a processor and memory for receiving sensor readings from the lamp sensor 150 and other sensors that may be provided. A rear interior section 170 of the light fixture 100 can house the power supply and may also contain control components such as a processor, memory and sensor components. The processor may provide functions such as controlling the output of the light engine 102 by controlling an associated power supply, applying dimming schedules, performing diagnostic functions, interfacing with sensors for determining performance of the light fixture 100, and transmitting and receiving data through a wireless, or wired, network interface to a communications network or directly to a portable or handheld device. The wireless network may enable peer-to- peer connection, area network, mesh network, or mobile network communications. Alternatively a power line communications wired interface may be provided.

Figure 8 is a partial cross-section side view along a length of a front section of the outdoor light fixture. The lamp sensor 150 is positioned internally in the front section of the outdoor light fixture 100 angled towards the rear section of the outdoor light fixture 100. The angle of the lamp sensor 150 may be determined based on the expected amount of reflection from the transparent pane 132 in a particular position and may vary based upon the material used for the transparent pane 132 and lens module 106. In a non-limiting example, the lamp sensor 150 is positioned at an angle of about 25 to 35 degrees with respect to the surface defined by the horizontal plane of the transparent pane 132. The lamp sensor 150 is positioned at the front of the fixture to receive light directed in the preferential direction of the outdoor light fixture 100 proportional to the amount of light that would fall on the ground below the fixture, however, the location of the lamp sensor 150 may vary based upon the internal design of the light fixture and the lens module 106 design. An internal space 180 is defined between the lens module 106 of the light engine 102 and the transparent pane 132.

As shown in Figure 9, which is a partial cross-section side view along a length of the front section of the outdoor light fixture 100, the lamp sensor 150 is positioned to receive reflected light 192 of the light 190 from the space 180 generated by the light engine 102 directed towards an illumination area of the outdoor light fixture 100. The positioning of the lamp sensor 150 receives light proportional to the light output of the light engine 102. The lamp sensor 150 may alternatively be placed in other locations of the light fixture where reflections from the transparent pane 132 can be received based upon the design of the light fixture housing.

Although the outdoor light fixture disclosed is described as having one light engine, the fixture may have multiple light engines and the lamp sensor may only receive light from a subset of the LEDs associated with one of the light engines. In a multiple light engine configuration the depreciation seen by the lamp sensor can reasonably be assumed to apply to all the light engines in a single fixture, in a similar way that one or more lamp sensor enabled fixtures can be used as representative of multiple fixtures without lamp sensors. Alternatively the outdoor light fixture may have multiple lamps sensors, each for receiving light from a different light engine. Data from multiple lamp sensors may be utilized to characterize the different light engines or provide an averaging function to the data received from the multiple lamp sensors.

Figure 10 is a block diagram illustrating a management server for the management of multiple outdoor light fixtures which can communicate via a network. In this example, an outdoor light fixture 100 with a lamp sensor 150 is associated with multiple outdoor light fixtures 1050a, 1050b-1050n without lamp sensors, either geographically or based upon a common characteristic, which may for example be defined by installation data or manufacturing information by the management server 1030. Although only a single light fixture 100 is described, multiple outdoor light fixtures with lamp sensors 150 may be managed by the management server 1030 and used for controlling many outdoor light fixtures without lamp sensors based upon performance of fixtures with lamp sensors 150. The ratio of outdoor light fixtures with and without sensors may vary based upon system design and geographic distributions. The management server 1030 is a computing device which can collect data from the outdoor light fixtures 100 and store the data in storage device 1038 along with installation data associated with each light fixture via network interface 1034 via a network 1060. The management server 1030 may be directly coupled to the network 1060 or may access the network 1060 through one or more wired or wireless intermediary networks or networking devices. The installation data may for example include operating type, design, power levels, and location of each light fixture. The management server 1030 builds a database which contains data collected via the network 1060, from reporting outdoor light fixtures 100 providing time-stamped lamp sensor output data, and other sensor data comprising but not limited to temperature, ambient temperature, LED board/module temperature, power supply temperature, luminaire energy/power consumption, LED array current, and humidity. The management server 1030 can communicate with the outdoor light fixtures 100, and 1050a, 1050b-1050n via a network 1060 to send and receive data and provide schedules or compensation data such as power levels. The network 1060 may utilize any type of data network communication such as but not limited to a service provider wired or wireless network infrastructure, ad-hoc or mesh wireless network communications, or peer-to-peer network. The management server 1030 may also provide a user interface 1034 or enable remote user access for configuration, management, or analysis functions to be performed. The management server 1030 can collect data for individual outdoor light fixtures which can be analyzed, trended and notifications generated when particular depreciation targets are exceeded or expected to be exceeded. Alternatively, the management server 1030 may not be required to directly communicate with the outdoor light fixtures 100, and 1050a, 1050b-1050n if an alternative data collection and programming method is utilized. For example, if a handheld data collection device is utilized to collect data from the outdoor light fixtures and for programming the light fixtures, the data may be provided to the management server 1030 via another communication network or uploaded directly.

The outdoor light fixture 100 comprises a light engine system 1008 comprising one or more light engines and one or more power supplies, a network interface 1004 for communication via the network 1060, and a processor 1002 with a memory 1006 for operation of the outdoor light fixture 100. The processor 1002 is configured to operate the outdoor light fixture 100 by executing instructions from memory 1006, including, for example, communicating with the management server 1030, controlling components in the light fixture such as the power supply, storing configuration data, maintaining data-logs, processing incoming and initiating outgoing communications and messages via a network 1060 at a certain time interval or in response to a request from the management server 1030, collecting data from the lamp sensor 150, and other sensors 1012 (e.g., a day/night sensor, a humidity sensor, an ambient temperature sensor) and/or controlling and monitoring power usage. The lamp sensor 150 monitors the output of the light engine 102, by receiving reflected light output as discussed above and provides a characteristic such as a sensor value which can be correlated with a detected illuminance level defined relative to the luminous flux (lux) incident on a surface, per unit area. The behavior of the lamp sensor 150 in a single outdoor light fixture 100 may not be stable or consistent from reading to reading, and in addition, the lamp sensor's output may be affected by environmental conditions such as temperature, and humidity etc. Therefore, additional sensors 1012 may included such as temperature sensors on the lamp sensor, light engine, and external sensors, voltage or current sensors. Data determined by the lamp sensor 150 and additional sensors 1012 are stored in nonvolatile memory 1006 of the outdoor light fixture 100. The outdoor light fixture 100 can then provide the data to the management server 1030 when requested, or at a defined interval, through an network interface 1004. The management server 1030 can also provide operational parameters to change or adjust power levels of the outdoor light fixture 100, and generate notifications when particular lumen deprecation levels have occurred and determine trends in light engine performance relative to environmental, equipment (i.e. LED driver performance) or installation factors.

Outdoor light fixtures 1050a, 1050b-1050n may be wirelessly accessible but not have sensor functionality. The outdoor fixtures 1050a, 1050b-1050n each have a processor 1052, coupled to a light engine system 1058 for receiving commands wirelessly via a network interface 1054. The parameters, operational functions or programming instructions may be stored in non-volatile memory 1056. Data collected from the outdoor light fixture 100 by the management server 1030 can determine a depreciation of the light engine 102 and also determine power levels that may be applied to light fixtures 1050a-1050n when the hardware configurations are similar and would therefore have similar life expectancy and output performance.

The management server 1030 analyzes the data collected from sensor- enabled outdoor light fixtures to determine operational trends, averages, life expectancy of the light engine and determine depreciation rates. In addition, the management server 1030 may provide parameters to the light fixture based upon the collected data such as compensation in drive levels to be applied to control illumination levels provided by the outdoor light fixture 100, but may also be applied to similar outdoor light fixtures. Depending on the implementation, the compensation could be determined solely based on the readings on a fixture-by-fixture basis or it may be averaged by a combination of data from similar or same outdoor light fixture types, which may result in more consistent adjustment across the deployment. The data collection and analysis may be based upon short term environmental conditions or based upon seasonal averaging between winter and summer relative to temperature changes. The management server 1030 may determine a lumen maintenance value. The lumen maintenance value provides a relative depreciation value of the light output of the light engine 102 against the light output when it is first installed. Lumen maintenance is often specified as L50, L70, L80, or L90 where L stands for lumen maintenance and the number is the percentage of light output remaining. The management server 1030 may trend the depreciation to determine when a particular lumen maintenance value will be reached, for example L70, and may also provide notification when the lumen maintenance occurs for the outdoor light fixture. The parameters used for compensation of the power levels provided by the power supply of the light fixtures may be based upon desired life expectancy or a target light output to maintain a lumen level and may be the result of performance averaging over an extended period of time. Alternatively, the compensation of power levels may be adjusted for a particular time period (daily, weekly, monthly, and seasonally) if an appreciable performance impact is expected on the outdoor light fixture relative to the environmental conditions. The light output may be changed by adjusting the current delivered to the LEDs by the power supply to meet a desired performance target, for example changing the expected L70 target date. In a further non-limiting example, the processor 1032 in the management server 1030 is configured to analyze, over the long-term, the degradation of light fixtures deployed over multiple customers, locations, etc. to build up a compensation algorithm that could be applied to future installations while installing fewer units with lamp sensors as confidence in the stability of the design increases. It would be appreciated that the light fixtures 100, 1050a, and 1050b...1050n and the management server 1030 may include components not shown in the drawings. As shown in Figure 1 1 the management server 1030 may send a request to receive configuration or performance data from light fixtures having sensor monitoring capability (1 102). The request may be a schedule provided to the outdoor light fixture, either initially or periodically to determine when the data should be provided to the management server 1030. Alternatively, individual polling requests may be generated to each outdoor light fixture. In response to the request, or at a scheduled interval, the light fixture, or light fixtures, returns a list of the time-stamped data stored in its non-volatile memory. The data may include sensor data but also operational data or readings such as voltages or currents of the fixture. The management server receives (1104) the list of the time-stamped data from the light fixture and stores them in a database. The data can then be analyzed to determine a depreciation amount of the outdoor light fixture and a possible life expectancy of the outdoor light fixture (1106). If the outdoor light fixture is to provide a constant lumen output, the management server may determine parameters to be applied to the outdoor light fixture such as a compensation value (e.g., new power level to be applied to the power supply), and conduct an action by sending commands based on the determination (1108). Alternatively, the parameters may adjust a power level to achieve a desired lifespan, such as defined by a lumen maintenance level, which is accomplished by increasing or decreasing output levels. The compensation value may be determined on an individual light fixture basis or averaged from data obtained from a group of fixtures having lamp sensors and/or similar operating characteristics. The new parameters may also be sent over the wireless network to a group of outdoor light fixtures, which may or may not have lamp sensors, but having similar behaviour or characteristics as the outdoor light fixture(s) (from which the data set was obtained) and in order to compensate for depreciation of light output (1 110). Alternatively, a group of outdoor light fixtures may be compensated based on their average behavior to filter out anomalies/variability in sensor accuracy/stability from light fixture to light fixture. The light engine system may alternatively be dimmed to reduce the degradation of light output from the LEDs of the light engine which may also be monitored by the lamp sensor 150. For example by dimming the light engine system the length of time to reach lumen maintenance targets may be extended and also provide data on how much the programmed parameters can impact performance of the light engine.

Figure 12 is a flow diagram of processes for sensor reading executed in the outdoor light fixture. During normal operation of the streetlight, the outdoor light fixture is set to baseline power level for determining depreciation such as 100%, or another convenient level output (1202). This may occur when the outdoor light fixture is initially turned on at dusk or occur at a consistent period during the night. The outdoor light fixture may be allowed to warm up and stabilize for a period of time (1204), after which various data (1206) from sensor(s) are determined. The data read from the sensor(s) are recorded (1208) by the processor in the light fixture. In particular the data may include the output from the lamp sensor providing a characteristic indicative of incident light on the lamp sensor, but may also include other sensor data collected from the fixture. The data is then stored (1210) in a nonvolatile memory in the light fixture with a timestamp. The stored data is sent to the management server through a wireless interface in response to a trigger event (1214), e.g., a request from the management server or a defined reporting interval or once sensor data is collected. If a dimming schedule is applied, the outdoor light fixture may return to its normal operation such as defined by a dimming schedule if implemented (1218). The management server may provide parameters to the outdoor light fixture, such as new power levels (1214) based upon the performance of the outdoor light fixture or a group of outdoor light fixtures if collected data is averaged across a group of outdoor light fixtures. The parameters can then be applied to the light engine system to adjust the light output (1216). The outdoor light fixture may apply the received parameter every day whether or not parameters were sent and received from the management server that particular day. In addition, the baseline power level may be associated with the parameters previously provided by the management server. Figure 13 is another flow diagram of processes executed in the management server. In this method a parameter request message is sent wirelessly to an outdoor light fixture (1302). The outdoor light fixture can then send time-stamped data to the management server (1304). The data is then stored in a database (1306). A depreciation compensation interval may be associated with the depreciation data that have been received. When the interval expires (YES at 1308) the collected data may be analyzed to determine a rate of light depreciation of the outdoor light fixture (1310). The depreciation interval may, for example, be a number of days, months, or season changes, after which the stored data is then analyzed to determine variation in the data or based upon a defined variation in the received data to determine a new power level to be applied to the light engine system to compensate for depreciation of the light intensity. Otherwise, (NO at 1308) data from the reporting outdoor light fixture continues to be collected and stored (1302). Additional data analysis may be performed to determine the light engine degradation based upon the lamp sensor 150 readings trended against additional sensor data (1311) or other relevant factors. For example, the light output may vary based upon environmental conditions which may vary seasonally and geographically. Data from multiple outdoor light fixtures may be utilized in determining the new power level. Control commands can then be generated to adjust the power levels of the outdoor light fixture ( 312). Depending on the granularity of control provided the power levels may be applicable to more than one outdoor light fixture, for example light fixtures having the equivalent or similar installation parameters, operating type, design, and/or power levels. If multiple outdoor light fixtures can utilize the determined power levels (YES at 1314) the power levels are addressed and sent to multiple outdoor light fixtures (1316). If the power levels are only determined for an individual outdoor light fixture (NO at 1314) the power levels can be sent to the particular outdoor light fixture (1315). The compensation interval can then be reset (1318).

Figure 14 is another flow diagram of processes executed in the outdoor light fixture providing the ability for the fixture to provide local compensation based upon degradation of the light engine. In this embodiment the outdoor light fixture can adapt performance based upon the lamp sensor output without direct control by the management server, yet it may still receive updates from the management server, controlling how it responds to fixture depreciation. During normal operation of the streetlight the light fixture is set to a baseline output level (1402). This may occur when the outdoor light fixture is initially turned on at dusk or at a consistent period during the night. The outdoor light fixture may be allowed to warm up and stabilize for a period of time (1404), after which lamp sensor data (1406) and various data from other sensor(s) may be determined. The data can then be sent to the management server (1408), either when variations occur, for example the depreciation is greater than a previous reading, a defined interval or whenever they are retrieved or after a defined number of readings. The management server may utilize the data to determine trends in light engine performance for a particular outdoor light fixture or for an installed base of outdoor light fixtures. The processor of the outdoor light fixture may then determine a depreciation amount (1410). Actions may be defined by a set of compensation parameters to adjust the outdoor light fixture output based upon the lamp sensor reading. Based upon performance of the outdoor light fixture, or multiple outdoor light fixtures, the management server may update the actions defined by the set of compensation parameters (1409) and send the update to the outdoor light fixture on an as needed basis. If the depreciation parameter has an action associated with it in the set of compensation parameters (YES at 1412) such as new power levels are determined to compensate for depreciation of the light engine (1414) or reduce the output of the light engine to extend its expected life. The parameters can then be applied to the light engine, which may be performed by changing parameters associated with the power supply of the outdoor light fixture (1416) to adjust the output.

One or more currently preferred embodiments have been described by way of example. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims. Although the description discloses example methods, system and apparatus including, among other components, software executed on hardware, it should be noted that such methods and apparatus are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of these hardware and software components could be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and/or firmware. Accordingly, while the following describes example methods and apparatus, persons having ordinary skill in the art will readily appreciate that the examples provided are not the only way to implement such methods and apparatus.

Claims

An outdoor light fixture comprising:

a light engine positioned within a housing of the outdoor light fixture, the light engine including a plurality of light emitting diode (LED) light sources and a lens module having a plurality of optical elements for each of the plurality of LED light sources;

a lamp sensor positioned within a housing of the light fixture, the lamp sensor directed towards a transparent pane covering the lens module to receive light from the light engine reflected by the transparent pane; and

a processor configured to determine a characteristic from the lamp sensor and store the characteristic to non-volatile memory with an associated timestamp.

The outdoor light fixture of claim 1 wherein the lamp sensor is configured to receive reflections from the transparent pane installed substantially perpendicular to an axis of maximum light engine output.

The outdoor light fixture of claim 2 wherein the lamp sensor is positioned forward of the light engine pointing toward the transparent pane.

The outdoor light fixture of claim 2 wherein the lamp sensor is installed at an angle with respect to a planar surface of the transparent pane.

The outdoor light fixture of claim 4 wherein the lamp sensor is positioned to receive light reflections from the transparent pane proportional to an amount of light provided below the light fixture.

The outdoor light fixture of claim 4 wherein the angle is between 25 to 35 degrees from the planar surface of the transparent pane.

The outdoor light fixture of any one of claims 1 to 6 further comprising one or more sensors for determining a temperature of the lamp sensor.

8. The outdoor light fixture of any one of claims 1 or 7 further comprising sensors for determining one or more of: a light engine temperature, an external temperature, a power supply temperature, a humidity, an LED engine current level, and a supply line voltage level.

9. The outdoor light fixture of any one of claims 1 to 8 further comprising a network interface for sending and receiving data to the management server.

10. The outdoor light fixture of claim 9 wherein the determined characteristic is sent to the management server and the management server provides one or more parameters to the outdoor light fixture to adjust an output of the light engine.

11. The outdoor light fixture of any one of claims 1 to 10 wherein the lamp sensor is a photo-sensor.

12. The outdoor light fixture of any one of claims 1 to 1 1 wherein the processor is configured to determine a lumen maintenance value or target date for a desired lumen maintenance value of the light engine based on sensor outputs from the sensor system.

13. A method for management of an outdoor light fixture, the method comprising: receiving at a management server data from an outdoor light fixture representing a lamp sensor characteristic from a lamp sensor for sensing light output from a light engine having a plurality of light emitting diode (LED) light sources of the outdoor light fixture; determining at the management server a depreciation rate of the light engine based upon the received lamp sensor characteristic; and

sending a parameter from the management server to the outdoor light fixture in response to the determined depreciation rate to adjust the light output of the light engine of the outdoor light fixture. The method of claim 13 further wherein the parameter is associated with a power level determined to achieve a lumen output or lumen maintenance value by the light engine of the outdoor light fixture.

The method of claim 13 or 14 wherein the parameter is sent to one or more second outdoor light fixtures having similar behaviour or characteristics as the outdoor light fixture having the lamp sensor.

The method of any one of claims 13 to 15 further comprising:

receiving at the management server data from a group of outdoor light fixtures having lamp sensors wherein determining the depreciation rate is based on an average performance of the group of outdoor light fixtures to filter out anomalies or variability in lamp sensor accuracy or stability between outdoor light fixtures wherein an average depreciation rate is determined.

The method of any one of claims 13 to 16 further comprising:

sending from the management server a request to the outdoor light fixture via a network to receive the lamp sensor characteristic from the outdoor light fixture.

The method of any one of claims 13 to 16 further comprising:

receiving at the management server the data on a periodic basis from the outdoor light fixture.

The method of any one of claims 13 to 19 wherein received data further comprises values for one or more sensors associated with the outdoor light fixture.

The method of any one of claims 13 to 19 further comprising:

generating a set of compensation parameters; and providing the set of compensation parameters to the outdoor light fixture.

21. The method of any one of claims 13 to 20 wherein the lamp sensor is configured to receive reflections from the transparent pane installed substantially perpendicular to the axis of maximum LED light sources output.

22. The method of any one of claims 13 to 21 wherein the lamp sensor is installed in a housing of the outdoor light fixture and senses reflected light from a horizontal plane of a transparent pane for covering the lens module.

23. The method of claim 22 wherein the lamp sensor is positioned to receive light reflections from the transparent pane proportional to an amount of light provided below the light fixture.

24. The method of claim 23 wherein the angle is determined based on the expected amount of reflection from the transparent pane proportional to an amount of light provided below the light fixture.

25. A system for management of a plurality of outdoor light fixtures, the system comprising: an outdoor light fixture for:

determining a lamp sensor characteristic from a lamp sensor positioned within a housing of the outdoor light fixture receiving light from a light engine including a plurality of light emitting diode (LED) light sources; and

storing the lamp sensor characteristic to non-volatile memory with an associated timestamp;

a management server for:

receiving data from the outdoor light fixture include the lamp sensor characteristic and the associated time stamp;

determining a depreciation rate of the light engine based upon the received lamp sensor characteristic; and sending a parameter to the outdoor light fixture in response to the determined depreciation rate to adjust the output of the light engine.

26. The system of claim 25 wherein the parameter is associated with a power level to be applied to a power supply of the outdoor light fixture, the parameter determined to achieve a lumen output or lumen maintenance value by the light engine of the outdoor light fixture.

27. The system of claim 25 or 26 wherein the parameter is sent to one or more second outdoor light fixtures having similar behaviour or characteristics as the outdoor light fixture having the lamp sensor.

28. The system of any one of claims 25 to 27 wherein the management server receives data from a group of outdoor light fixtures having lamp sensors wherein determining the depreciation rate is based on an average performance of the group of outdoor light fixtures having lamp sensors to filter out anomalies or variability in lamp sensor accuracy or stability between outdoor light fixtures wherein an average depreciation rate is determined.

29. The system of any one of claims 25 to 28 wherein the management server sends a request to the outdoor light fixture via a network to receive the data providing lamp sensor characteristic from the outdoor light fixture.

30. The system of any one of claims 25 to 28 wherein the management server receives the data on a periodic basis from the outdoor light fixture.

31. The system of any one of claims 25 to 30 wherein received data further comprises values for one or more sensors associated with the outdoor light fixture.

32. The system of any one of claims 25 to 31 wherein the management server: generates a set of compensation parameters; and provides the set of compensation parameters to the outdoor light fixture.

33. The system of any one of claims 25 to 32 wherein the lamp sensor is configured to receive reflections from the transparent pane installed substantially perpendicular to the axis of maximum LED light sources output.

34. The system of any one of claims 25 to 33 wherein the lamp sensor is installed in a housing of the light fixture and senses reflected light from a horizontal plane of a transparent pane for covering the lens module.

35. The system of claim 34 wherein the lamp sensor is installed at an angle with respect to a planar surface of the transparent pane and the transparent pane of the outdoor light fixture is substantially perpendicular to the axis of maximum light engine output.

36. The system of claim 34 wherein the angle is determined based on the expected amount of reflection from the transparent pane proportional to an amount of light provided below the light fixture.