AND MONITORING

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of Patent Application 12/719,681 , filed March 8, 2010.

TECHNICAL FIELD

The present invention is related to lighting systems, and, in particular, to automated control systems for control ling and monitoring individual lighting elements, lighting elements associated with individual fixtures, and arbitrarily sized groups of lighting fixtures located across local, regional, and larger geographical areas, particularly LED-based lighting. BACKGROUND OF THE INVENTION

Lighting systems for public roadways, thoroughfares, and facilities, private and commercial facilities, including industrial plants, office-building complexes, schools, universities, and other such organizations, and other public and private facilities account for enormous yearly expenditures of energy and financial resources, including expenditures for lighting-equipment acquisition, operation, maintenance, and administration. Because of rising energy costs, falling lax- generated funding for municipalities, local governments and state governments, and because of cost constraints associated with a variety of different enterprises and organizations, expenditures related to acquiring, maintaining, servicing, operating, and administering lighting systems are falling under increasing scrutiny. As a result, almost all organizations and governmental agencies involved in acquiring, operating, maintaining, and administering lighting systems are seeking improved methods and systems for control of lighting fixtures in order to lower administrative, maintenance, and operating costs. SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to control of lighting systems at individual-light-fixture, local, regional, and larger-geographical- area levels. One embodiment of the present invention comprises a hierarchical lighting-control system including an automated network-control center that may control up to many millions of individual lighting fixtures and lighting elements, regional routers interconnected to the network-control center or network-control centers by public communications networks, each of which controls hundreds to thousands of individual light fixtures, and light-management units, interconnected to regional routers by radio-frequency communications and/or power-line communications, each of which controls components within a lighting fixture, including lighting elements, LED-luminaire drivers, sensors, and other devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 illustrates a portion of a traditional lighting system observed in parking lots, along thoroughfares and roadways, and within industrial sites, school facilities, and office-bui lding complexes.

Figure 2 shows a modestly sized industrial or commercial site with associated lighting-fixture locations.

Figures 3A-B illustrates a conceptual approach to lighting-system control that represents one embodiment of the present invention.

Figure 4 i llustrates, using the same industrial-site layouts shown in

Figure 2, groupings of individual lighting fixtures to facilitate automated control, as made possible by lighting-control systems that represent embodiments of the present invention.

Figure 5 il lustrates a displayed schedule for automated control of the various groups of lighting fixtures shown in Figure 4 according to certain embodiments of the present invention.

Figure 6 provides a generalized architecture for the automated hierarchical lighting-control system that represents one embodiment of the present invention. Figure 7 provides a block diagram for a radio-frequency-enabled light- management unit according to one embodiment of the present invention.

Figure 8 provides a block diagram for a stand-alone routing device according to one embodiment of the present invention.

Figure 9 illustrates communications between routers, radio- frequency- enabled light-management units, and end-point light-management units according to one embodiment of the present invention.

Figure 10 illustrates division of the 256 possible command codes into four subsets, according to certain embodiments of the present invention.

Figure 1 1 shows the type of data stored within each light-management unit according to certain embodiments of the present invention.

Figures 12A-B illustrate data managed by a router for all of the different light-management units or light-fixtures which the router manages according to certain embodiments of the present invention.

Figure 1 3 shows various commands used in router-to-light- management-unit communications according to certain embodiments of the present invention.

Figures 14A-N show the data contents of the various commands and replies discussed above with reference to Figure 13.

Figures 15- 18 provide flow-control diagrams for the control functionality with a light-management unit according to one embodiment of the present invention.

Figure 19 provides a state-transition diagram for one router user interface that represents one embodiment of the present invention.

Figure 20 shows a block diagram for the RF-enabled LMU that represents one embodiment of the present invention.

Figure 2 1 provides additional description of the microprocessor component of the RF-enabled LMU that represents one embodiment of the present invention.

Figure 22 provides a circuit diagram for a portion of the optocouple- isolation subcomponent of the RF-enabled LMU that represents one embodiment of the present invention. Figure 23 provides a circuit diagram for one embodiment of the swiiched-relay component of the RF-enabled L U that represents one embodiment of the present invention.

Figure 24 provides a circuit diagram for the internal-power-supply component of the RF-enabled LMU that represents one embodiment of the present invention.

Figure 25 provides a circuit diagram for the power-meter component of an RF-enabled LMU that represents one embodiment of the present invention.

Figure 26 provides a circuit diagram for a circuit that interconnects output from a sensor or monitor device to an interrupt-like input to the microprocessor according to one embodiment of the present invention.

Figure 27-29 illustrate characteristics of LED-based lighting elements.

Figure 30 illustrates a LED-based street-light luminaire.

Figures 3 1 -33 illustrate one type of constant-output-current LED lamp driver.

Figure 34 i llustrates an RF-enabled LMU/LED-based-luminaire-driver module that represents one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

There are many different types of lighting fixtures, lighting elements, or luminaires, and lighting applications. Figure 1 illustrates a portion of a traditional lighting system observed in parking lots, along thoroughfares and roadways, and within industrial sites, school facilities, and office-building complexes. Such lighting systems commonly employ street-light fixtures, such as street-light fixtures 102- 104 in Figure I . Each street-light fixture includes a rigid, vertical pole 1 10 and arms or brackets 1 12, through which internal electrical wiring runs, that together support one or more lighting units I 1 . Each lighting unit generally includes one or more lighting elements and associated electrical ballasts that limit voltage drops across, and current drawn by, lighting elements and that buffer voltage and/or current surges and shape the input voltage or current in order to provide a well-defined output voltage or current for driving the lighting elements. Many different types of lighting elements are currently used, including light-emitting-diode ("LED") panels, inductive-lighting, or compact fluorescent, elements, high-pressure-sodium lighting elements, mercury- hal ^' ide lighting elements, incandescent lighting elements, and other types of lighting elements. A series of lighting fixtures is often interconnected along a common 5 electrical path within a public-utility electrical grid. Lighting fixtures arc often controlled by photocel l switches 1 16, which respond to ambient illumination and/or lack of ambient i l lumination, to power on lighting elements during periods of darkness and power off lighting elements when adequate ambient daylight is available.

10 Even modestly sized industrial, commercial, educational, and other facilities often employ a large number of lighting fixtures for a variety of different purposes. Figure 2 shows a modestly sized industrial or commercial site with associated lighting-fixture locations. The industrial site shown in Figure 2 includes an adm inistration building 202, an operations building 204, three laboratory buildings

15 206-208, and three parking lots 210-212. The locations of lighting fixtures are shown as filled disks, such as fi lled disk 214. Certain of the lighting fixtures are located along roadways, such as lighting fixture 220, and may serve to illuminate the roadways as wel l as illuminating portions of buildings adjacent to the roadways, building entrances, walkways, and other portions of the environment surrounding the0 buildings and roadways. This type of lighting provides safety for operators of motor vehicles and pedestrians, and may address certain security concerns. Other lighting fixtures, including double-arm lighting fixtures 224-226, illuminate parking lots, and are employed primari ly for the convenience of parking-lot users as wel l as for security purposes. Other lighting fixtures, including the lighting fixtures that surround the5 laboratory buildings 206-208, including lighting fixture 230, may serve primarily for facilitating security in and around high-security buildings and areas.

There are many problems associated with even simple lighting systems, such as those shown in Figures 1 and 2. Photocell control of lighting fixtures is relatively crude, providing 100 percent power to light fixtures during0 periods of darkness and no power to light fixtures during periods of adequate ambient light. Thus, lighting is controlled primarily according to day length, rather than to the needs of facilities and people who work in, and travel through, the facilities. Photocells and photocell-control circuitry may fail, leading to lighting fixtures remaining constantly powered on, significantly shortening the useful length of lighting elements and significantly increasing energy consumption by lighting fixtures. As discussed with reference to Figure 2, various different lighting fixtures within a facility may be used for different purposes, and therefore could optimally be controlled according to different schedules and lighting-intensity requirements, were such control possible. However, current lighting systems generally lack effective means for differentially operating lighting fixtures and lighting elements within them. For these and many other reasons, manufacturers and vendors of lighting fixtures and lighting systems, organizations and agencies responsible for acquiring, operating, maintaining, and administering lighting systems, and ultimately all who enjoy the benefits of lighting systems continue to seek improved systems for controlling lighting systems, so that lighting can be provided as cost effectively as possible to meet various different lighting needs and requirements.

As discussed above, current lighting systems, in which individual lighting fixtures are controlled generally by photocells, and in which groups of electrically interconnected lighting fixtures may be additionally controlled at the circuit level by timers and other crude control mechanisms, do not provide flexibility and precision of control needed to optimize control of lighting systems in order to provide needed lighting intensities at particular times on an individual-lighting-fixture basis, monitor lighting fixtures for output, component failure, and other operational characteristics, and provide local-arca-wide, regional, and larger-geographical-area- wide approaches to control of lighting systems. By contrast, embodiments of the present invention provide precise control of lighting fixtures, regardless of electrical- connection topologies, in local, regional, and larger areas through automated control systems, public communications networks, including the Internet, radio-frequency communications, and power-line communications. Embodiments of the present invention thus provide for flexible, scheduled, and control led operation of lighting fixtures down to the granularity of individual lighting elements within individual lighting fixtures and up to arbitrarily designated groups of lighting fixtures that may include millions of lighting fixtures distributed across large geographical areas. In addition, embodiments of the present invention provide for automated monitoring of lighting elements, lighting fixtures, and the environment surrounding lighting fixtures made possible by flexible control of light-management units, lighting-fixture- embedded sensors, and bi-directional communications between light-management units, routers, and network-control centers. Embodiments of the present invention provide for control of active components included in lighting fixtures, including automated activation of heating elements, failure-amelioration circuitry, and other such local functionality by the hierarchical control systems that represent embodiments of the present invention.

Figures 3A-B illustrates a conceptual approach to lighting-system control that represents one embodiment of the present invention. According to this embodiment of the present invention, lighting-system control is implemented hierarchically, with a top-level network-control center 302 directly communicating with multiple routing devices 304-310, each of which, in turn, communicates with one or more radio-frequency ("RF")-enabled bridging lighting-fixture-management units ("LMUs") 320-33 1 within individual fixtures that control operation of the lighting fixtures and that, in turn, communicate with one or more end-point LMUs within individual lighting fixtures via power-line communications. In general, the network-control center communicates with routers via network communications, including the Internet. However, network-control centers may also employ cellular telephone network communications, radio-frequency communications, and other types of communications in addition to network communications, in alternative embodiments. The routers intercommunicate with LM Us via radio-frequency communications, power-line communications, and, in alternate embodiments of the present invention, using other types of communications. In certain embodiments of the present invention, RF-enabled, bridging LMUs intercommunicate with routers using radio-frequency communications, and the RF-enabled, bridging LMUs communicate with additional end-point LMUs via power-line communications.

' Each router, such as router 304, is associated with a number of individual lighting fixtures containing LMUs, such as the lighting fixtures within the region enclosed by dashed line 340 in Figure 3, that intercommunicate with the router to provide control of the lighting fixtures. The routers, in turn, communicate with a network-control center 302 that provides for centralized, automated control of all of the lighting fixtures controlled by all of the routers that communicate with the network-control center. In one embodiment of the present invention, there are four levels within the hierarchy of controllers: ( 1 ) the centralized network-control center 302; (2) a number of routing devices 304-310; (3) F-enabled bridging LMUs; and (4) additional end-point LMUs that communicate with the RF-enabled bridging LMUs via power-line communications. In alternative embodiments of the present invention, additional hierarchical levels may be included so that, for example, multiple network-control centers may communicate with a higher-level central control system for control of a very large geographical region. Alternatively, multiple geographically separated network-control centers may be implemented to interoperate as a distributed network-control center. Note that the lighting fixtures controlled through a particular router, such as the lighting fixtures within the area surrounded by dashed curve 340, are not necessarily geographically distinct from the lighting fixtures controlled by another router. The LMUs contained within individual lighting fixtures provide policy-driven, individualized, automated control over each of one or more lighting elements within the lighting Fixture, provide for manual control of lighting elements, receive and process data from sensors, and control various active devices within lighting fixtures. Up to 1 ,000 or more LMUs may communicate with, export data to, and receive policy directives and data from, a particular routing device, and the network-control center may communicate with, receiving data from, and export policy directives to, up to 1 ,000 or more routing devices. Thus, the nctwork- control center may provide automated control of a mil lion or more individual lighting fixtures.

While embodiments of the present invention allow individual lighting elements within individual lighting fixtures to be manually controlled from user interfaces provided by routing devices and user interfaces provided by the network- control center, manual control would be tedious and error prone. Automated lighting- control systems that represent embodiments of the present invention provide the ability to logically aggregate individual lighting fixtures into various different groups of l ighting fixtures for control purposes. Figure 4 illustrates, using the same exemplary industrial-site layout shown in Figure 2, groupings of individual lighting fixtures to faci l itate automated control, made possible by lighting-control systems that represent embodiments of the present invention. As shown in Figure 1 , the various different lighting fixtures, represented by filled disks, such as filled disk 220, are combined into 1 1 different control groups. Lighting fixtures along a public thoroughfare, including lighting fixture 220, are grouped together into a first group 402, labeled with the group number " 1 ." Lighting fixtures behind the administration building and operations buildings 202 and 204, along a smaller roadway 404 and a large parking lot 212, are divided into two groups: ( 1 ) group 2 (406 in Figure 4); and (2) group 3 (408 in Figure 4). By partitioning these lighting fixtures into two groups, alternate lights along the roadway and parking lot can be activated on alternate days, lowering energy consumption and increasing lighting-element operational lifetimes. Alternatively, al l of these lighting elements could be combined in a single group, and operated at lower light-intensity output in order to achieve similar purposes. Similarly, the dual-arm l ighting elements within parking lot 212 are divided into two groups 4 10 and 4 12 so that lighting elements on only a single arm of each dual-arm lighting fixtures are powered on during a given day. Groups can be as small as individual lighting fixtures, such as groups 6 and 7 (420 and 422 in Figure 4) or even as small as individual lighting elements within lighting fixtures. The hierarchical, automated control of lighting can be feasibly scaled, according to various embodiments of the present invention, to control all of the lighting fixtures within an entire nation or continent. The hierarchical implementation of the automated lighting control system that represents one embodiment of the present invention provides both scalability and communications flexibility. As one example. Figure 3B shows a portion of a lighting-control system that uses a number of different types of communications methodologies. In Figure 3B, a router 350 manages LMUs within eight di fferent lighting fixtures 352-359. The lighting fixtures are partitioned into two different groups, including a first group 352-355 serially interconnected by a first power line 360 emitted from a transformer 362 and a second group 356-359 serially interconnected by a second power line 364 emitted from the transformer 362. Were both groups of lighting fixtures connected to a single power line, without the transformer 362 separating the two groups of lighting fixtures, all of the LMUs within the lighting fixtures could directly communicate with the router using only power-line communications. However, power-line communications cannot bridge transformers 362 and various other electrical-grid components. It would be possible to use two routers, one for each group of lighting fixtures, and interconnect each router to its respective group of lighting fixtures using power-line communications. However, a two-router implementation would involve connection and location constraints with regard to the routers, unnecessary duplication of router functionality, and higher cost. Instead, according to various embodiments of the present invention, the router 350 communicates by radio-frequency communications with RF-enabled, bridging LMUs in each of lighting fixtures 354 and 358. Each RF-enabled, bridging LMU intercommunicates with the remaining lighting fixtures of the group of lighting fixtures in which the bridging LMU is located using power-line communications. The bridging LMUs serve both as a local LMU within a lighting fixture as well as a communications bridge through which end-point LMUs in each group can receive messages from, and transmit messages to, the router 350. Thus, radio-frequency communications and RF-enabled, bridging LMUs provide a cost-effective and flexible method for bridging transformers and other power-line-communications- intcrrupting components of an electrical system. In addition, each LMU may include cell-phone-communications circuitry to allow the LMU to communicate directly with a cellular telephone 370. A cellular telephone can act as a bridge to a router or as a specialized, local router, to enable maintenance personnel to manually control an LM U during various monitoring and servicing activities.

In certain embodiments of the present invention, LMUs control operation of lighting elements within lighting fixtures according to internally-stored schedules. Figure 5 illustrates a displayed schedule for automated control of the various groups of lighting fixtures shown in Figure 4 according to certain embodiments of the present invention. Schedules may be displayed, in various ways, by router and network-control-center user-interface routines, allowing interactive definition, modification, and deletion of schedules by authorized users. As shown in Figure 5, a schedule for lighting-element operation within the lighting fixtures of each of the 1 1 groups shown in Figure 4 is provided for a particular day. Each horizontal bar, such as horizontal bar 502, represents the schedule for operation of lighting elements within the lighting fixtures of a particular group according to the time of day. In certain embodiments of the present invention, entire lighting fixtures, including all lighting elements within the lighting fixtures, are assigned to groups, while in alternative embodiments of the present invention, individual lighting clcmenls within lighting fixtures may be separately assigned to groups. The time of day increments from 12:00 a.m., at the left-hand edge of the horizontal bar 504, to 12:00 p.m. 506 at the right-hand edge of the horizontal bar. Shaded regions within the horizontal bar, such as shaded region 508 in horizontal bar 502, indicate times during which the lighting elements should be powered on. The heights of the shaded regions indicate the level to which the lighting element should be powered on. For example, shaded region 5 10 in horizontal bar 1 indicates that the lighting elements within the lighting fixtures of group 1 should be powered on to 50 percent of maximum intensity between 12:00 a.m. and 2:00 a.m., while the right-hand portion of shaded region 508 indicates that the lighting elements within the lighting fixtures within group 1 should be powered on to maximum intensity from 6:30 p.m. until midnight.

In addition, event-driven or sensor-driven operational characteristics can be defined for each group. For example, in Figure 5, small horizontal bars, such as horizontal bar 5 14, indicate how the lighting elements should be operated when various different events occur. For example, horizontal bar 5 14 indicates that, in the event that the photocell output transitions from on to off, indicating that the ambient lighting has increased sufficiently to trip the photocell-signal-output threshold, the lights, when already powered on at or above 50% of maximum intensity, should be operated for an additional 15 minutes at 50 percent of maximum l ight-intensity output, represented by shaded bar 3 16, and then powered off. Operational characteristics can be specified for the photocell-on event, indicating a transition from adequate lighting to darkness, and for an input signal from a motion sensor indicating motion within the area of a lighting fixture. Operational characteristics for many additional events may be specified, as well as operational characteristics for additional control lable devices and functionality, including heating elements activated to remove snow and ice, various failure-recovery and fail-over systems, and other such devices and functionality.

There are many different approaches to specifying lighting-element operation and many different considerations for providing the different operational characteristics represented by the different horizontal bars for each group shown in Figure 5, which in turn represent encoded operational schedules and event-related operational directives. For example, it would make no sense to power on lighting elements in response to a photocell-off event. The intent of the small shaded bar 5 1 6 within horizontal bar 5 14 is that, had the lights been powered on to greater than 50 percent of maximum intensity, lighting elements should be powered down to 50 percent of maximum intensity for a brief period of time before being powered off entirely. Thus, a combination of the time-incremented, large horizontal bar 502 and smaller horizontal bar 514 may specify that, at any point in time, the light should be powered on to the minimum power level indicated in the timc-of-day schedule bar and the shorter horizontal bar corresponding to the photocell-off event. However, in other cases, light may need to be powered on to the maximum power level indicated in the time-of-day schedule bar and a different, shorter horizontal bar corresponding to a different type of event. In general, the ultimate operational characteristics of a light fixture, implemented by an LMU installed within the light fixture, may be defined by arbitrary Boolean and relational-operator expressions or short interpreted scripts or computer programs that compute, for any particular point in time, based on sensor input signals and on the stored time-based schedule and stored operational characteristics associated with particular events, the degree to which the lighting element should be powered on.

Figure 6 provides a generalized architecture for the automated hierarchical lighting-control system that represents one embodiment of the present invention. Large-area control is exercised over many lighting fixtures within a large geographical area via automated control programs running within a network-control center 602. The network-control center includes, in addition to the control programs, one or more relational database management servers 603 or other types of datastorage systems and multiple web servers, or other interface-serving systems, 605-607 that together comprise a distributed, automated lighting-control-system nelwork- control center. The network-control center web servers serve lighling-syslem-control information to multiple routers 610-613 via the Internet 616 or via radio-frequency transmitters 61 8. In addition, the network-control center may provide a web-site- based network-control-center user interface 620 via a personal computer or work station 622 interconnected with the network-control center by the Internet or a local area network. In certain embodiments of the present invention, the network-control center may provide functionality similar to that provided by individual routers, including the ability to monitor the state of individual LMUs, define groups, define and modify schedules, manually control lighting fixtures, and carry out other such tasks that can be carried out on a local basis through the user interface provided by a router. In addition, the network-control center may provide additional functionality, not provided at the router level, including computationally complex analysis programs that monitor and analyze various characteristics of lighting systems, including power consumption, maintainability, and other such characteristics, over very large geographical areas.

The routers may be implemented in software that runs on a laptop or personal computer, such as router 61 1 , may be stand-alone devices, such as routers 610 and 612, or may be stand-alone devices associated with a personal computer or workstation on which stand-alone routers display user interfaces provided to users, as in the case of router 613 in Figure 6. Routers communicate with RF-enabled LMUs 630-640 via wireless communications, including 1EEE802. I 5 (Zigbee) communications, and the RF-enabled LMUs may both control a particular lighting fixture as well as act as a bridge between additional end-point LM Us with which the bridge LMUs communicate via power-line communications, including Echelon Power Line (A Si/EIA 709.1 -A). In certain embodiments of the present invention, routers may communicale to LMUs via power-line communications, such as router 612 and LMU 633 in Figure 6. In still further embodiments of the present invention, other types of communications may be employed for communicating information between network-control centers and routers, between routers and bridge LMUs or end-point LMUs. and between bridge LMUs and end-point LMUs. Various different chip sets and circuitry can be added to LMUs, routers, and components of network- control centers to enable additional types of communications pathways.

Both bridge LMUs and end-point LMUs control operation of lighting elements within light fixtures and collect data through various types of sensors installed in the light fixtures. Both types of LMUs control lighting-fixture operation autonomously, according to schedules downloaded into the LMUs from routers and network-control centers or default schedules installed at the time of manufacture, but may also directly control operational characteristics of lighting fixtures in response to commands received from routers and network-control centers. The schedules and other control directives stored within LMUs may be modified more or less arbitrarily by users interacting with user interfaces provided by routers and network-control centers. While, in many applications, the control functionality of the LMUs is a significant portion of the automated lighting-system control functionality provided by embodiments of the present invention, in many other applications, monitoring functionality provided by LMUs is of as great a significance or greater significance. The LM Us architecture provides for connecting numerous different sensor inputs to LMUs, including motion-sensor inputs, chemical-detection-sensor inputs, temperature-sensing inputs, barometric-pressure-sensing inputs, audio and video signal inputs, and many other types of sensor inputs in addition to voltage and power sensors generally included in LMUs. The LMUs' response to each of the different types of input signals may be configured by users from user interfaces provided by routers and network-control centers. The various types of sensor input may be used primarily for providing effective control of lighting-system operation, in certain cases, but also may be used for providing a very large variety of different types of monitoring tasks, at local, regional, and large-geographical -area levels. LMU sensing can be employed, for example, for security monitoring, for monitoring of traffic patterns and detection of impending traffic congestion, for facilitating intelligent control of traffic signals, for monitoring local and regional meteorological conditions, for detecting potentially hazardous events, including gunshots, explosions, release of ^' toxic chemicals into the environment, fire, seismic events, and many other types ol ^" events, real-time monitoring of which can provide benefits to municipalities, local government, regional governments, and many other organizations.

Figure 7 provides a block diagram for a radio-frequency-enabled light- management unit according to one embodiment of the present invention. The RF- cnablcd LMU includes an RF antenna 702, a wireless communications chip or chip set 704 that provides for wireless reception and transmission of command and response packets, a power-line-communications chip or chip set 706 that provides for power-line reception and transm ission of command and response packets, a noise filter 707 that band-pass filters noise from the power-line connections, a CPU 708 and associated memories for running internal control programs that collect and store data, that control lighting-element operation according to stored data and stored programs, and that provide forwarding of packets from RF to PL communications and from PL to RF communications, an internal power supply that converts AC input power to DC internal power for supplying DC power to digital components, an optocouple isolation unit 710 that isolates the CPU from power surges, a dimming circuit 712 that provides digital pulse-width modulation of the electrical output to lighting elements to provide a range of output current for operating certain types of lighting elements over a range of light-intensity output, a digital-to-analog circuit 714 that provides controlled voltage output to lighting elements or other components, and a switched relay 716 for controlling power supply to various devices or components within a lighting fixture, including ballasts.

Figure 8 provides a block diagram for a stand-alone routing device according to one embodiment of the present invention. The stand-alone routing device includes many of the same elements as included in the RF-enabled LMU, as shown in Figure 7, with the addition of a local -area -network communications controller and port 802 and other communications components 804 and 806 that allow the stand-alone router to interconnect with a personal computer or workstation for display of a user interface. Figure 9 illustrates communications between routers, radio- frequency- enabled light-management units, and end-point light-management units according to one embodiment of the present invention. Both commands and responses arc encoded in packets comprising between seven and 56 bytes for RF communications. The RF communications protocol is a command/response protocol that allows routers to issue commands to RF-enabled L Us and receive responses from those commands and that allows RF-enabled LMUs to issue commands to routers and receive responses to those commands from the routers. Broadcast messages and oneway messages are also provided for. Each command or response packet includes a six-byte I D 902, a single-byte command identifier or code 904, and between zero and 49 bytes of data 906. The ID 902 is used to identify particular LM U or RF-enabled L Us from among the LMUs that communicate with the router. The commands and responses are packaged within power-l ine-communications applications packets for communications via power-line communications via the Echelon power-line communications protocol.

Figure 10 il lustrates division of the 256 possible command codes into four subsets, according to certain embodiments of the present invention. In Figure 10, a central horizontal column 1002 includes the 256 different possible command codes that can be represented by the one-byte command-code field within the communications packets used both for RF communications and PL communications. The even-numbered command codes correspond to commands, and the odd- numbered command codes correspond to responses, with the response for a particular command having a numeric value one greater than the numeric value of the command code for that particular command. Command codes and response codes for router-to- end-point-LMU commands have the lower-valued codes, represented as the code values above horizontal dashed line 1004. Router-to-bridge LMU commands have the higher-valued command codes, represented by the command codes below the horizontal dashed line 1004. Thus, a bridge LMU can immediately determine, from the command code, whether a command received from a router should be processed by the bridge LM U for local control of a light fixture or forwarded, via PL communications, to downstream LMUs. Similarly, the end-point-LMU-to-router commands have lower-numbered command codes and the bridge-LMU-to-router commands have higher numerically valued command codes. Any particular command code, such as command code ^* '0" 1006, may correspond to a router-to- LMU command or to an LMU-to-router command. The routers and LMUs can distinguish these different commands because the router receives only LMU-to-router commands and LM Us receive only router-to-LMU commands.

Figure 1 1 shows the type of data stored within each light-management unit according to certain embodiments of the present invention. Each LMU stores information for each of up to a fixed number of lighting elements 1 102- 1 105, a number of group identifiers 1 1 12 that identify groups to which the LMU is assigned, various input/output device descriptors 1 1 14, the status for each of various different events 1 1 16, and a schedule 1 1 18 comprising up to some maximum number of operational directives. Each set of information describing a particular lighting element, such as the information that describes lighting element ^* '0" 1 102, includes a lamp-status 1 120 with a bit indicating whether or not the lighting element is powered on or off 1 12 1 and a field indicating the degree to which the light is powered on with respect to the maximum light-intensity output of the light 1 122. In addition, the total hours of operation for the lighting clement 1 124, total operation of the ballast associated with the lighting element 1 126, and the number of power-on events associated with the lighting element 1 128 are stored, along with various additional types of information, in particular embodiments of the present invention. Information regarding the light fixture 1 108 includes a current power consumption 1 130, a current or instantaneous voltage across the lighting fixture 1 132, a current drawn by the lighting fixture 1 134, an accumulated energy used by the lighting fixture 1 136, flags that indicate whether particular alarms, other sensor inputs, or other input signals are active or inactive 1 1 38, and a set of flags indicating whether or not particular relays and other output components are active or inactive 1 140. Lighting fixture information also includes a cumulative light status 1 142 that indicates whether or not any of the light elements associated with the light fixture are on or off. The status bits 1 1 10 include a variety of different bit flags indicating various types of problems, including override events, sensor failures, communications failures, absence of stored data needed for control of light-element operation, and other such events and characteristics. The I/O device descriptors 1 14 provide a description of the meaning of each of various input signals that can be monitored by the LMU. Each operational directive within the schedule 1 1 1 8 includes an indication of the day 1 150. start time 1 152, end time 1 1 54, and lamp status 1 156 associated with the directive, as well as a group ID 1 1 58 that indicates a group to which the directive applies.

Figures 12A-B illustrate data managed by a router for all of the different light-management units or light-fixtures which the router manages according to certain embodiments of the present invention. In Figures 12A-B, a set of relational-database tables arc provided to indicate the types of information maintained by a router regarding the LMUs managed by the router. Of course, any number of various different database schemas may be designed to store and manage in formation for routers in alternative embodiments of the present invention. The relational tables shown in Figures I 2A-B are intended to provide an exemplary database schema in order to illustrate the types of data stored within a router. The relational tables of the exemplary schema include: ( 1 ) Component Type 1202, which lists the various types of components within a lighting-control system, including internal components of lighting fixtures and lighting elements as well as LMUs, routers, and other components; (2) Address 1204, which includes various different addresses referenced from other tables; (3) Manufacturer 1206, which contains information about particular component manufacturers; (4) Maintainer 1208, which contains information about various maintenance individuals or organizations responsible for maintaining components of the automated lighting control system; (5) Administrator 1210, which contains information about various administrative organizations or individual administrators that administrate portions of the lighting-control system; (6) additional tables describing individuals or organizations responsible for supplying power, supplying various other services, and other such individuals and organizations, not shown in Figures 12A-B; (7) Components 1212, which stores detailed in formation about particular components within the lighting-control system; (8) Elec 1214, which stores detailed electrical characteristics of particular system components, the rows of which are referenced from rows of the Components table; (9) Software 1 2 16, which stores detailed software characteristics of particular system components, the rows of which are referenced from rows of the Components tabic; ( 10) Mechanical 12 1 8, which stores detailed mechanical characteristics of particular system components, the rows of which are referenced from rows of the Components table; ( 1 1 ) Contains 1220, which stores pairs of component IDs that form the relationship "contains," indicating the first component ID of the pair identifies a component that contains the component identified by the second component ID of the pair; ( 12) Manages 1222, which stores a "manages" relationship between components; and ( 13) Groups 1224, which contains information about various groups of LMUs defined for the router.

In the exemplary data schema shown in Figures 12A-B, the Component Type table 1202 contains ID/description pairs that describe each of the different types of components in the automated lighting system. The IDs, or identifiers, are used in the CT ID column of the Component table 12 12. The Address 1204, Manufacturer 1206, Maintainer 1208, and Administrator 1210 tables include rows that provide descriptions of addresses, in the case of the Address table, and individuals or organizations, in the case of the Manufacturer, Maintainer, and Administrator tables. Each entry in the component table 1212 describes a different component within the automated lighting system. Each component is identified by an identifier, or ID, in the first column 1230 of the component table. Each component has a type, identified by the component-type identifier included in the second column 1232. Each component has a manufacturer, identified by a manufacturer ID in the third column 1234 of the Component table, where the manufacturer IDs are manufacturer identifiers provided in the first column 1236 of the Manufacturer table 1206. Components are additionally described by warranty information, in columns 1240 and 1242, an installation date, in column 1244, a serial number, in column 1246, references to rows in the Elec, Software, and other tables in columns 1248, 1250, and additional columns not shown in Figure 12 A, and by a GPS location, in column 1252. Many other types of information may be included in additional columns that describe components. The Elec table 1214 describes various electronic characteristics of a component, including the estimated lifetime, in column 1254, an accumulated runtime for the component, in column 1256, the number of povvcr-on events associated with the component, in column 1258, and various thresholds, in columns 1260, 1262, and additional columns not shown in Figure 12B, for triggering events associated with a component. As one example, column 1260 includes a run- time alert that specifies that the lighting-control system should take some action when the accumulated runtime hours are equal to or greater than the threshold value shown in column 1260. The Software and Mechanical tables 1216 and 12 1 8 include various characteristics for software components and mechanical components. Each group, in the Groups table 1224, is described by an ID, in column 1270, a name, in column 1272, various IDs for administrators, maintainers, and other service providers associated with the group in columns 1274, 1276, and additional columns not shown in Figure 12B, the component I D of a router associated with a group, in column 1278, and the current schedules for the group, in an unstructured column 1280.

Information stored in exemplary data schema shown in Figures 12A-B aJlows for responding to many different types of queries generated by user-interface routines executed on a router or network data center. For example, if a user of the router-provided user interface wishes to find al l poles, or light fixtures, in the Supermall parking lot group, the following SQL query can be executed by router user-interface routines to provide serial numbers and GPS coordinates for the identified poles:

Select G PS, SeriaINo

From Component C, ComponentType CT

Where C.CTID = CT.1D AND

CT. Description = 'pole' AND

C.ID IN

(Select CID2 From Manages M l

Where M l . CID l IN

(Select CID2 From Manages M2

Where M2.CID 1 IN

(Select RID From Groups G

Where G.Name = 'Supermall Pkg'

)

)

) In certain embodiments of the present invention, a database stored locally within the router or stored in a database management system accessible to the router via the network-control center may automatically trigger generation of messages sent from the router to LMUs when data is added or updated. In other embodiments of the present invention, the user interface routines may execute queries to update the database, in response to user input through the user interface, and, at the same time, generate commands for transmission to LMUs, when appropriate. In certain cases, a separate, asynchronous router routine may periodically compare the contents of the database to information stored within the LMUs to ensure that the information content of the LMUs reflects the information stored within the database. In general, the information stored within the LMUs, including status, run-time characteristics, definitions of sensors, and other such information, is also stored in the database of the router.

Routers exercise control over LMUs through a command interface. Figure 13 shows various commands used in rouler-to-light-managemcnt-unil communications according to certain embodiments of the present invention. These commands include: ( I ) the set-time command, which sets the time stored with an LMU; (2) the define-groups command, which sets entries in the list of groups ( 1 1 12 in Figure 1 1 ) to which an LMU belongs; (3) the define-schedule command, which is used to define schedules stored within LMUs; (4) the define-input/output command, which defines the various sensor devices and associated events within LM Us; (5) the force-lamp-state command, which provides for manual operation of a lighting unit via the LMU by a user interacting with the router through the user interface or, in alternative embodiments, by a user interacting with a cell phone; (6) the report-status command, which solicits status information by the router from LMUs; (7) the report- siatus-command reply, several forms of which are used to respond to report-status commands received by LMUs; (8) the event command, which reports events and which can be sent by any unit; (9) the set-operating-hours command, which allows the router to set various electrical characteristics for components within a lighting fixture maintained by an LMU; ( 10) the define-lamp-characteristics command, which al lows the router to store particular lamp characteristics for lighting elements within the LMU that manages those lighting elements; ( I I) the firmware-update command, which prepares an LMU for reception of a firmware update; ( 12) the backdoor command, a debugging command used to obtain data from LMUs; and ( 1 3) the add/remove command, which informs a bridging LM U of the addition or deletion of an end-point LMU from the bridging LMU's power-line network. Figures 14A-N show the data contents of the various commands and replies discussed above with reference to Figure 13. The tables describing data fields of messages, provided in Figures I 4A-N, are self-explanatory, and are not discussed further.

Figures 1 5- 18 provide flow-control diagrams for the control functionality with a l ight-management unit according to one embodiment of the present invention. Figure 1 5 provides a control-flow diagram for an LM U event handler, which responds to events that arise within an LMU. The event handler waits for a next event to occur, in step 1502, and then determines which event has occurred, and responds to the event, in the set of conditional statements, such as conditional statement 1504. that follow the wait step 1502. The event handler runs continuously within the LMU. When an asynchronous sensor event has occurred, such as the output signal from a photocell transitioning from on to off or from off to on, as determined in step 1 504, then the event descriptor for the event is found in the table of events ( 1 1 16 in Figure 1 1 ) and updated. When a timer has expired indicating that it is time to check the various events for which event descriptors arc supplied in the list of events ( 1 1 16 in Figure 1 1 ), a check-events routine is called, in step 1 508. When the event corresponds to queuing of an incoming message to an incoming message queue, as determined in step 15 10, then a process-received-commands routine is called in step 15 12. When the event corresponds to queuing of an outgoing message to an outgoing-message queue, as determined in step 1 514, then a proccss- outgoing-commands routine is called in step 15 1 8. When the event represents expiration of a timer controlling periodic checking of the stored operational schedule, as determined in step 1 520, then a check-schedule routine is called in step 1 522. Any of various other events that may occur are handled by a default event handler, evoked in step 1 524. The events explicitly handled in Figure 15 are merely a set of exemplary events, used to illustrate overall functionality of the LM U event handler. Figure 16 provides a control-flow diagram of the check-events routine, called in step 1 508 of Figure 1 5. In the /or-loop of steps 1602- 1 608, each event descriptor in the list of event descriptors (1 1 1 6 in Figure 1 1 ) within an LM U is considered. If the event is described as being active, or having more recently occurred than handled, then, in general, a message reporting the event is queued to an outgoing message queue, in step 1604, and, when local action is warranted, as determined in step 1 605, the event is handled locally in step 1606. Following message queuing and local handling, the event status is reset, in step 1 607. Other types of events may be reported, but not handled locally. Other types of events may both be reported to the router as well as handled locally. For example, a temperature- sensor event may elicit local activation or deactivation of a heating element in order to locally control temperature.

Figure 17 provides a control-flow diagram of the routine "process received commands" called in step 1 5 12 of Figure 15. The next command is dequeued from an incoming command queue in step 1702. When the command is a retrieve-information command, as determined in step 1704, then the appropriate information is retrieved from the information stored by the LMU and included in a response message that is queued to an outgoing-message queue, in step 1706. A queue-not-empty event is raised, in step 1708, upon queuing the message to the outgoing message queue. When the command is a store-information command, as determined in step 1708, then information received in the command is stored into the appropriate data structure within the LMU, in step 1 71 0. When an acknowledgement is needed, as determined in step 1712, then an acknowledgement message is prepared, in step 1714, and queued to the outgoing message queue. When the command elicits local action, as determined in step 1716, then the local action is carried out in step 1 71 8 and, when an acknowledgment message is required, as determined in step 1720, the acknowledgement message is prepared and queued in step 1 714. When the command queue is empty, as determined in step 1 722, then the routine ends. Otherwise, control returns to step 1702 for dequeuing the next received command.

Figure 18 provides a control-flow diagram for the routine "check schedule," cal led in step 1522 of Figure 15. In the yor-loop of steps 1802- 1810, each entry in the schedule ( 1 1 18 in Figure 1 1 ) stored locally within the LMU is considered. Current time is compared to the start-time and end-time entries of the currently considered schedule, in step 1 803. When the current time is within the range specified by the start-time and end-time entries of the currently considered schedule event or entry, then, in the inner /or-loop of steps 1805-1 809, each lighting element within the light fixture controlled by the LMU is considered. When the currently considered lighting element is within the group for which the schedule entry is valid, as determined by comparing the group ID of the schedule entry with the group ID of the lighting element, then when the current lighting-element output is different from that specified by the schedule, then, in step 1 808, the LM U changes the output of the lighting element to that specified in the schedule by altering the voltage or current output to the lighting element.

Figure 19 provides a state-transition diagram for one router user interface that represents one embodiment of the present invention. When a iiser interacts through a user interface with a router, the router initially displays a home page 1902. The user may wish to view data, update and modify data, or manually control one or more LMUs and, in certain embodiments of the present invention, may- select one of these three types of interactions and undergo authorization in order to carry out these types of actions through one or more authorization pages 1904- 1906. Users may be required to provide passwords, pass fingers over fingerprint identifiers, provide other information that authorizes the user to carry out these and other types of tasks by interacting with the user interface. Various sets of web pages may allow a user to view or modi fy groups defined for LMUs and the association of LMUs with groups, calendar-like schedule of desired lighting operation, information regarding lighting fixtures and components contained within lighting fixtures, and information regarding fixture locations, including the ability to view fixture locations overlaid onto maps or photographic images of the area within which the LMUs are contained. There are a large ^' number of different possible user interfaces that can be devised to provide interactive control of LMUs and lighting fixtures managed by a particular router. Similar user interfaces may be provided at the network-control center level. Figures 20-26 provide additional description of the radio-frequency- enabled light-management unit ("RF-Enabled LMU") discussed above with reference to Figure 7. Figure 20 shows a block diagram for the RF-enabled LMU that represents one embodiment of the present invention, similar to the block diagram shown in Figure 7, with additional detail and with dashed-line indications of subcomponents, circuit diagrams for which are provided in Figures 21 -26. The circuit diagrams provided in Figures 21 -26 include addition description of the following subcomponents, indicated by dashed-line rectangles in Figure 20: ( 1 ) the microprocessor 2002; (2) the optocouple-isolation subcomponent 2004; (3) the switched-relay subcomponent 2006; (4) the internal-power-supply subcomponent 2008; and (5) a power-meter subcomponent 2010. The power-meter component 2010 is an integrated-circuit-implemented power meter that monitors power usage of the luminaire or luminaires that receive electrical, power through the AC power lines 2012-2013. Software routines within the RF-enabled LMU query the power-meter component 2010, generally at regular intervals in time and/or upon requests received from a router or network control center, in order to monitor power usage by the luminaire or luminaires managed by the RF-enabled LMU and report the power usage back to the router or network-control centers.

Figure 2 1 provides additional description of the microprocessor component (2002 in Figure 20) of the RF-enabled LMU that represents one embodiment of the present invention. The microprocessor 2102 includes a large number of pins, to which external signal lines are coupled, that provide an interface between the microprocessor and other RF-enabled-LMU components. In Figure 21 , the pins are numerically labeled from 1 to 32. Interrupt-like signals 2104-2105 are input to pins 12 and 13 by various sensor or monitor components of the RF-enabled LM U. The microprocessor outputs a relay signal 2106 to the switched-relay component (2006 in Figure 20) to disconnect the luminaire from the AC power source. The microprocessor receives a signal 2108 from a thermistor temperature sensor in order to monitor the temperature within the light-fixture housing in which the RF-enabled LMU resides. A group of signals 21 10 provide a universal- asynchronous-receiver-transmitter ("UART") interface to the wireless module (704 in Figure 7) and another group of signal lines 21 12 provides an interface to the power- line communications module (706 in Figure 7). Signal lines 21 14-21 1 5 provide a clock input to the microprocessor and the group of signal lines 21 16 implements a scrial-peripheral-interface ("SPl") bus interface to the power-meter component (2010 5 in Figure 20). Another group of signal lines 21 1 8 implements a pulse-width- modulation output. Several pins connect the microprocessor to internal DC power 2 120 and to ground 2122. The microprocessor 2 102 includes flash memory for storing software programs that implement control and communications functionalities of the RF-enabled LMU, as well as traditional processor subcomponents, including

J O registers, arithmetic and logic units, and other such subcomponents. Any of a variety of di fferent microprocessors may be employed in RF-enabled LMUs that represent embodiments of the present invention.

Figure 22 provides a circuit diagram for a portion of the optocouple- isolation subcomponent (2004 in Figure 20) of the RF-enabled LMU that represents

15 one embodiment of the present invention. Input and output lines are electronically isolated from one another by an optical connection 2202 in which electronic signals are converted to light signals and the light signals converted back to electronic signals by a light-emitting diode ("LED") and photodiode, respectively.

Figure 23 provides a circuit diagram for one embodiment of the0 switched-relay component (2006 in Figure 20) of the RF-enabled LMU that represents one embodiment of the present invention. When the relay signal 2302 is deassei ted, a solenoid switch or solenoid-switch-like device 2304 condiictively interconnects input AC power to output AC power. However, when the relay signal 2302 is asserted by the microprocessor (2102 in Figure 21 ), the solenoid decouples 5 the input AC power lines from output AC power lines, thus disconnecting the luminairc from the main input power lines. When the microprocessor is not functioning, and prior to assertion of control over a light fixture by the microprocessor and microprocessor-resident software control programs within the RF-enabled LMU, the luminaire is connected to the AC-input main power lines, as a0 default state. Thus, prior to initialization of the microprocessor and control programs, and whenever the microprocessor and/or control programs fail to actively control the components of the light fixture, the luminaire is directly connected to the main power lines. As discussed above, the luminaire may be disconnected from the main power lines under RF-enabled LMU control as a result of commands received from a router or network-control center.

Figure 24 provides a circuit diagram for the internal-powcr-supply component (2008 in Figure 20) of the RF-enabled LMU that represents one embodiment of the present invention. Input AC power 2402-2403 is rectified and stepped down, by a rectifier and transformer 2404 to produce five-volt internal DC output 2406. The output power signal is stabilized by stabilization circuitry and components, including capacitor 2408.

Figure 25 provides a circuit diagram for the power-meter component (2010 in Figure 20) of an RF-enabled LMU that represents one embodiment of the present invention. The power meter is implemented as an integrated circuit 2502 that interfaces to the microprocessor via the SPl bus interface 2504 discussed above with reference to Figure 21.

Figure 26 provides a circuit diagram for a circuit that interconnects output from a sensor or monitor device 2602 to an interrupt-like input 2604 to the microprocessor according to one embodiment of the present invention. The output signal 2604 is asserted when the voltage drop across sensor-output signal lines is greater than a threshold value.

For many reasons, light-emitting-diode ("LED") based area lighting, including street lighting, is rapidly becoming a preferred lighting technology in many applications, including street-lighting applications. LED-based lum inaires provide signi ficantly greater energy efficiency than incandescent bulbs, fluorescent lighting elements, and other lighting element technologies. LED-based luminaires can be implemented and controlled to produce output light with desired spectral characteristics, unlike many other types of lighting elements, which output light of particular wavelengths or wavelength ranges. LED-based luminaires can be quickly powered on and off, and achieve full brightness in time periods on the order of microseconds. The output from LED-based luminaires can be easily controlled by pulse-width modulation or by controlling the current input to the LED-based luminaire, allowing for precise dimming. LED-based luminaires tend (o fail over time, rather than abruptly failing, as do incandescent or fluorescent lighting elements. LED-based luminaires have li fetimes that are longer than the lifetimes of other types of lighting elements by factors of between 2 and 10 or more. LED-based luminaires are generally more robust than other types of lighting elements, being far more resistant to shock and other types of mechanical insults. For these and other reasons, LED-based luminaires are predicted to largely replace other types of lighting elements in street-lighting applications during (he next five to ten years.

However, despite their many advantages, LED-based luminaires have certain disadvantages, including a non-linear current-to-voltage response that requires careful regulation of voltage and current supplied to LED-based luminaires. In addition, LED-based luminaires are relatively temperature sensitive. For these and other reasons, RF-enabled-LMU control of LED-based luminaires may provide even greater advantages for LED-based lighting than for traditional types of lighting. For example, RF-enabled LMUs that represent embodiments of the present invention may include power meters and output-lumen sensors to facilitate automated monitoring of LED-based-luminaire output in order to determine when LED-based luminaires need to be replaced. In the case of traditional types of lighting elements, which abruptly fail, it is relatively easy for maintenance personnel to identify failed l ighting elements. By contrast, since LED-based luminaires fail gradually, monitoring by RF-enabled LMUs that represent embodiments of the present invention can provide a far more reliable, automated system for monitoring and detecting failing LED-bascd luminaires than monitoring by maintenance personnel. In addition, the RF-enabled LMUs that represent embodiments of the present invention can monitor temperature within lighting fixtures at relatively frequent intervals and can automatically lower power output to luminaires and lake other ameliorative steps to ensure that the temperature- sensitive LED-based luminaires remain within an optimal temperature range.

Figure 27-29 illustrate characteristics of LED-based lighting elements. Figure 27 shows a typical, small LED lighting device. The LED light source is a relatively small chip of semiconducting material 2702 across which a voltage dropped by a potential applied to the lighting device via anode 2704 and cathode 2706 elements. Typically, a semiconducting chip 2702 is mounted within a reflective cavity 2704 to direct light outward, in directions representing a solid angle defined by the reflective cavity. In higher-power LEDs, the semiconductor chip is of signi ficantly greater size and generally mounted to a metal substrate to provide for greater heat removal from the larger semiconductor chip.

Figure 28 illustrates a principal of LED operation. A semiconductor crystal that forms the light-emitting element of an LED device 28-2 is differentially doped to produce a p-n junction 2804. The p side of the crystal contains an excess of positive charge carriers, or holes, such as hole 2806, and the n side of the semiconductor contains an excess of negative charge carriers, or electrons, such as electron 2808. At the interface 2804 between the p and n portion of the semiconductor crystal, a shallow barrier region 2810 is formed in which electrons diffuse from the n side to the p side and holes diffuse from the p side to the n side. This barrier region represents a small potential-energy barrier to current flow. However, when a voltage is applied 2812 across the semiconductor in a forward direction, as shown in Figure 28, referred to as "forward biasing," the barrier is easily overcome, and current flows across the p-n junction. Reversing the polarity of the voltage source, referred to as "reverse biasing," can induce current to flow through the semiconductor in the opposite direction, although, when reverse current flow is allowed to increase past a threshold reverse current, su fficient heat is generated to disrupt the semiconductor lattice and permanently disable the device. Asymmetrically doped semiconductor crystals, which implement p-n junctions, comprise the basic functional unit of many components of modern electronic systems, including diodes, transistors, and other components. In the case of a light-emitting diode ("LED"), when the semiconductor chip is forward biased, and current flows across the p-n junction, excited electrons combine with holes in a process by which the electrons transition to lower energy levels by releasing light of a specific wavelength.

Figure 29 shows a current-versus-voltage curve for a typical LED. When 0 V is applied across the LED 2902, no current passes through the LED. Forward biasing of the LED produces a small initial current which increases exponentially past a threshold forward-biasing voltage 2904. Reverse biasing of the LED produces an exponential increase in reverse current flow past a breakdown- voltage threshold 2406. The LED emits lights that when an applied forward-biasing voltage exceeds the threshold voltage 2404 in Figure 29. However, the operational applied-voltage range within which light is emitted without sufficient current flow to destroy the semiconductor lattice is quite narrow. In other words, as shown in Figure 29, a LED exhibits a high degree of non-linearity in current flow with respect to applied voltage, and even small increases in applied voltage in the exponential regions of the current-versus-voltage curve can induce sufficient current flow within the device to destroy the device. For this reason, unlike in incandescent and fluorescent light elements, control of voltage or current output to an LED-based luminaire needs to be relatively precise. LED-based area lighting fixtures generally employ LED driver components that rectify input AC power and that output either constant-voltage or constant-current DC power to the luminaire.

Figure 30 illustrates a LED-based street-light luminaire. The LED- based street-light luminaire 3002, shown inverted from normal installation orientation, includes a transparent cover 3004 through which light emitted by LED elements, such as LED element 3006, in an array of LED elements 3008 passes to illuminate an area. The LED-based street-light luminaire includes a generally metallic housing 3010 with multiple fin-like projections, such as fin 3012, to facil itate heat removal from the LED array. The LED-based street-light luminaire may also include an LED driver that acts as a constant-voltage or constant-current power source for the LED array. Input power and signal lines run through a collar-like fixture 3014 that also serves as a mechanical couple to a light-fixture bracket. In alternative types of LED-based street-light lumitiaires, the LED driver may instead be placed within a component of a light fixture other than the luminaire housing, shown in Figure 30, and interconnected to the LED array by wiring threaded through the collar-like fixture.

Many types of LED drivers are commercially available. One popular LED driver, used in certain street-light applications, outputs a constant current of 0.70 A from input voltages of between 100 V and 277V. The LED driver includes thermal- protection circuitry and tolerates sustained open-circuit and short-circuit events in the LED array. The LED driver is housed within a long, rectangular enclosure weighting under three pounds and with dimensions of approximately 21 x 59 x 37 centimeters.

Figures 3 1 -33 illustrate one type of constant-output-current LED lamp driver. Figure 3 1 shows the LED-lamp-driver. The LED-lamp-driver drives a string, or series, of LEDs 3102 based on input AC power 3 104 using a fixed-frequency pulse-width modulation controller integrated circuit 3106. Figure 32 provides a functional block diagram for the integrated circuit (3106 in Figure 3 1 ) of the Led- lamp driver. Figure 33 provides a functional circuit diagram for the integrated circuit (3 106 in Figure 3 1 ) within the LED-lamp driver.

Figure 34 illustrates an RF-enabled L U/LED-based-luminaire-drivcr module that represents one embodiment of the present invention. As shown in Figure 34. the RF-enabled-LMU/LED-base-Iuminaire driver 3402 includes the RF-enabled LMU components 702, 704, 708, 710, 707, 709, and 716 discussed above with reference to Figure 7 as well as an additional switched relay 3406, LED-driver output subcomponent 3408, and a LED driver 3410 that recti fies and stabilizes input AC power to produce a constant-current DC output to an LED array 34 12. The additional switch relay 3406 is controlled in identical fashion as the switched relay 716 to ensure that, in a default mode prior to initialization of the RF-enabled LMU software or during periods of time in which the RF-enabled LMU is not actively controlling the light fixture, the LED driver is provided with input signals, in addition to input AC power, to drive light output from the LED array.

A problem that is addressed by a LED-driver-enhanced RF-enabled LMU that represents one embodiment of the present invention is that the power factor for a LED-driver coupled to one or more luminaircs is generally not 1 .0, as would be desired for max imum light output for minimum current drawn from the main, but generally significantly less than one. When the power factor is 1 .0, the waveform of the voltage matches that of the current within the load, and the apparent power, computed as the product of the voltage drop across the load and current that passes through the load, is equal to the power consumed within the load and ultimately dissipated to the environment as heat, referred to as the real power. Linear loads with only net resistive characteristics generally have a power factor of 1 .0. By contrast, linear loads with reactive characteristics, due to capacitance or inductance in the load, store a certain amount of energy and release the stored energy back to the main during each AC cycle. Therefore the apparent power provided to the load exceeds the real power consumed by the load. Non-linear loads, including rectifiers and pulse-width- modulation-based dimming circuits, change the voltage and current waveforms in complex ways, and may result in power factors significantly below 1 .0. LED-drivers include both rectifiers and pulse-width-modiilation-based dimming circuits, and therefore represent non-linear loads that have power factors significantly below 1 .0.

The problem with a power factor below unity is that more current is drawn by the load from the main power supplier than is actually used to generate power within the load. Although the excess current is not used in the load, and is returned to the power supplier through the main, the higher currents drawn by the load resu lt in higher power losses during transmission, as a result of which power suppliers often charge higher rates for supplying power to devices with low power factors. Thus, for maximum cost and energy efficiency, the LED driver incorporated into a LED-driver-enhanccd RF-enabled LMU needs additional circuitry and circuit elements to increase the power factor of the LED-driver-enhanced RF-enabled LMU and LED-driver-enhanced RF-enabled-LMU-controUed-luninaires to a value as close to 1 .0 as possible. The power factor of reactive, linear loads can also be increased by offsetting inductance in the load with added capacitance or offsetting capacitance in the load with added capacitance inductance, referred to as "passive power factor correction." The power factor of non-linear loads can be increased by using active circuit components, including boost converters, buck converters, or boost-buck converters, referred to as "active power factor correction." Depending on the particular implementation of the LED driver included in a LED-driver-enhanced RF- enabled LM U, the LED-driver-enhanced RF-enabled LMU needs additional active- power- factor-correction components, and, in certain cases, may also employ additional passive-power-factor-correction components. In general, loads with power factors of between 0.95 and 1 .0 are not subjected to higher fees by power suppliers, and thus the LED-driver-enhanced RF-enabled LMUs that represent embodiments of the present invention are desired to have power factors in excess that equal or exceed 0.95. And additional problem with LED drivers is that the power factor may decrease when dimming circuitry is active, due to pulse-width modulation that introduces additional harmonics into the voltage/current waveform. Thus, preferred LED-driver- enhanced RF-enabled LMUs that represent embodiments of the present invention include dynamic power-factor correction that can adjust to and correct dynamically the changing power factor of the LED-driver and coupled l minaires as the level of luminaire dimming changes.

Incorporation of an LED driver into the RF-enabled LMU provides a one-component solution for control of LED-based luminaires. For many reasons, the types of centralized monitoring and control of light fixtures made possible by RF- enabled LMUs that represent embodiments of the present invention arc of particular need in LED-based street-light fixtures. LED drivers and LED-based lum inaires have narrow operational parameter ranges, including narrow operational temperature ranges and relatively strict requirements for input voltage and input current due to the non-linearity of LED lighting elements. While certain types of temperature monitoring and control circuitry can be included in LED drivers, RF-enabled LMUs provide a second level of centralized, remote monitoring of operational parameters and both local and remote control over lighting fixture to minimize and/or eliminate occurrences of LED-driver-damaging and LED-array-damaging conditions. As discussed above, RF-enabled LMU control can provide for precise monitoring of power consumption and light output by LED-based luminaires in order to determine automatically and remotely the points in time at which luminaires need to be serviced and replaced. Furthermore, integrating the RF-enabled-LMU and LED-features together in a single module simplifies the design and manufacture of light-fixture components and reduces the cost of light fixtures.

Although the present invention has been described in terms of particular embodiments, it is not intended that the invention be limited to these embodiments. Modifications will be apparent to those skilled in the art. For example, a variety of different hardware configurations and designs may be used to implement end-point LMUs, bridge LM Us, routers, and network-control centers. As discussed above, many of various different communications methodologies can be employed for communications between hierarchical levels of components in a lighting-control system, according to embodiments of the present invention, by introducing proper chip sets, circuitry, and logic support within network-control- center hardware, router hardware, and LMU hardware. As discussed above, LMUs can be configured to accommodate many different types of sensor devices and to control many types of local electronic and electromechanical devices, such as heating elements, motors that control video cameras, and other such devices and components. Software and logic components of LMUs, routers, and network- control centers may be implemented in many different ways by varying any of the many different implementation parameters, including programming language, operating system platforms, control structures, data structures, modular organization, and other such parameters. Router and network-control-center user interfaces may be devised to provide many different types of automated lighting- system control and monitoring functionality. Lighting-fixture operation can be controlled by schedules, by specifying operational characteristics that follow particular events, can be controlled manually through manual-control user interfaces, and can be progra matically controlled in each of the different levels within the hierarchical automated lighting-system control systems that represent embodiments of the present invention, including relatively autonomous, programmatic control by individual LMUs.

The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. The foregoing descriptions of specific embodiments of the present invention are presented for purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments are shown and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in ihe art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents: