Patent Grant
10012375
Gas discharge lamps and incandescent lamps are well known in the art. Gas sources and incandescent lamps have relatively high energy consumption. Further, gas sources and incandescent lamps have relatively short lifetimes and are susceptible to breakage, typically leading to high maintenance costs. Further, the light intensity of gas discharge lamps tends to decrease over time with use. Additionally, gas discharge lamps produce ozone due the hazardous material/gas they require for excitation of electrons. After a gas discharge lamp's useful life, hazardous material and poisonous gases used in the lamp are released to environment affecting, among other things, the ozone layer. Additionally, gas discharge lamps produce ultra violet light that tends to cause deterioration of many materials, damage to some living organisms, and to some elements of the environment.
Solid state lighting, such as light emitting diode (LED) lighting has been developed to overcome some of the problems of gas discharge lamps and incandescent lamps. Many conventional LED devices, however, are limited by thermal energy-management issues.
It is known that LEDs exhibit negative temperature coefficient aspects, i.e. at fixed power input, as the device's operating heat rises, the device's light output decreases and it shortens the life of LED. It is, however, desirable to run LEDs using high current, because the higher the current, the higher the brightness of the emitted light. Further, high heat during use can shorten the useful life of an LED. Accordingly, there is motivation to remove heat as much as possible in order to operate an LED optimally with regard to power input and light output and LED life.
In addition, where a plurality of LED's are required for higher brightness, there are limits in conventional lamp technology to the number of LEDs within a defined space due to the problem of heat dissipation. Accordingly, it is desirable to cool an LED device in order to maximize energy efficiency and lifespan as well as to broaden design options.
Conventional solutions to undesirable thermal buildup include fans, cooling fins, spacing assemblies, etc. to reduce lamp housing temperature. Another conventional solution involves mounting LED modules on large conductive heat sinks. A light emitting diode (LED) must be mounted on a relatively large metal heat sink to dissipate the heat when the diode is run using high current. In high use and in demanding situations, the thermal transfer from the LEDs through a thermally connected conventional heat spreading plate to the housing is insufficient to maintain a desirable LED temperature. Unfortunately, thermal back-flow may occur as a lamp housing is heated by the ambient atmosphere beyond an optimal point which allows thermal conduction back to the heat spreading plate. In such situations, rapid LED degradation often occurs and unit efficiency drops.
Solid state thermoelectric modules (TEM), also referred to as thermoelectric coolers (TEC), or heat pumps, have been used in various applications. A TEM, in a thermocooling application, converts electrical energy into a temperature gradient, known as the “Peltier” effect. By applying a current through a TEM, a temperature gradient is created and heat is transferred from one side, the “cold” side of the TEM to the other side, the “hot” side.
The Peltier effect is well known by those skilled in the related arts and provides an active solid-state thermoelectric cooling function from a cool side to a hot side. The cool side is commonly placed against a surface or substrate which requires cooling. For example, the back surface of an LED assembly. The hot side is commonly placed against a surface or substrate which absorbs the transferred thermal energy and transfers it through conduction to a heat spreading plate. Through the utilization of these thermo-electric effects, thermal transfer from a cool side to a hot side can be controlled by controlling a current supplied to the thermo-electric effect.
Many conventional solid-state lamps are expensive to manufacture, and, due to the nature of the failures in a solid-state lamp, difficult and expensive to repair. Nevertheless, the energy-efficiency characteristics of solid-state lamps make them an attractive alternative to incandescent and fluorescent lighting.
For the foregoing reasons, there is a need for a solid-state lamp having effective thermal management with improved maintenance qualities.
A solid-state lamp has an efficient, reliable and flexible design. Modules of LEDs are supported in a frame enclosed in a housing. The frame has a number of angled panels supporting the modules at angles. The angled panels increase the angle of illumination from the lamp. The inner lamp housing and the frame are reflective and direct light substantially in the direction that the LEDs face. Some light, however, is directed in a secondary direction through upward facing windows in the housing. In order to maintain efficient light output from a lamp including LEDs, especially a lamp including high brightness LED arrays, it is beneficial for the lamp to be provided with an effective heat removal system. The heat removal system is connected in some embodiments to a heating element in the lamp covers to prevent fogging and icing in inclement weather.
In one lamp embodiment, angled extensions on each panel of the frame further increase the angle of illumination provided by the lamp in the primary direction of illumination, that is, the direction in which the LEDs are substantially facing. This configuration provides a larger spread of light which is advantageous for aisles, covered parking structures, and parking lots.
In another embodiment, the frame is centered in the housing with sufficient clearance from the edge of the fixture for maximum light projection in the primary direction of illumination.
In another embodiment, upward facing windows provide light upward thereby illuminating the space above the lamp. This tends to eliminate the cave effect that LED light fixtures have due to their inherent directional light characteristic.
In another embodiment of the lamp, a protective glass cover is readily removed and replaced. In one arrangement, the cover is set into the housing with a gasket. The cover is removable to service the lamp and is then replaceable to secure the fixture against dust and rain substantially back to the original condition. The servicing of the unit can be done in the field and its IP rating remains as that for the original fixture. By pushing the glass down, the glass holder slides out. Then the glass can be removed and LEDs can be serviced. Then the glass is put back. The glass is pushed up by the force of the rubber gasket. While pushing down on the glass, the 2 side glass holder are slid into the place and once the glass is released (or pushing down on glass is removed), the glass is pushed against the side metal rails and it would be water tight. In another embodiment of the lamp, the housing has ventilation openings as part of the passive cooling system for the LED modules. Each module includes at least one heat sink. The heat sinks are configured and located to enable effective passive cooling through air circulation. The housing in alternative arrangements includes a sliding bracket on the top and a hinged top cover enabling quick and simple installation. For example, in one arrangement, railings on the housing are configured to engage with inwardly bent edges on the top cover. This configuration enables the lamp fixture to be held in suspense while an installer is servicing the lamp or connecting wires for installation.
In another embodiment of the lamp, the glass cover protecting the LEDs includes a heat element. Heat at the heat sinks located on the LED modules is collected by thermal generators and converted to DC current. The current is supplied to the heat element in the glass to melt ice build up on the glass in the subfreezing weather.
The present invention together with the above and other advantages may best be understood from the following detailed description of the embodiments of the invention illustrated in the drawings, wherein:
A solid-state lamp is constructed using a plurality of replaceable and re-arrangeable LED modules. The replaceable modules typically include at least one light source module and a power supply module. The replaceability of the modules simplifies maintenance and repair of the lamp. The modules are supported in a frame enclosed in a housing. The frame has a number of angled panels supporting the modules at angles. The angled panels increase the angle of illumination from the lamp. The inner lamp housing and the frame are reflective and direct light substantially in the direction that the LEDs face. Some light, however, is directed in a secondary direction through upward facing windows in the housing. In an alternative embodiment, one or more upwardly directed LEDs are located behind the windows to increase the uplight from the lamp assembly. In a further alternative embodiment, strips of LEDs are located behind the windows. These upwardly directed LEDs are secured to the top side of a heat sink for proper heat transfer and heat dissipation.
An example implementation of the solid-state lamp assemblies is a networked configuration for lighting control in an indoor space such as a warehouse. The network enables the lamp assemblies (also referred to as “lamps”) to communicate with each other and with badges carried by the warehouse workers. As the workers move about the warehouse, the lamps provide more or less light in response to worker proximity. The response time for the system described is typically faster than conventional motion detector systems. Further, the lamp senses the presence of a badge in proximity to it and remains on even if the worker is substantially stationary for a prolonged period.
The LED die 105 is, for example, a chip of semiconducting material impregnated with impurities to create the p-n junction and configured to emit light when electrically biased. The LED die 105 has a thickness, for example, of 100-150 micrometers. The cooling device 110 is, for example, a thermo-electric device and is thermally engaged with the LED die such that heat is directed away from the LED die. An example thermo-electric device has a thickness of 10 micrometers. The thermo-electric device, also referred to as Peltier device, removes heat from the LED die through the Peltier effect. The thermo-electric device creates a temperature difference in response to an applied voltage. In one embodiment, the thermo-electric device is a thin film micro cooling device. In another embodiment, the thermo-electric device is a nanotechnology device. The cooling device is for example a nanocooler available from nanoCoolers of Austin, Tex. Alternatively, the cooling device is a thin film thermo-electric device available from Micropelt GmbH of Freiburg, Germany. In one embodiment, the cooling device is coupled to the LED die using conventional semiconductor attachment method such as soldering. In an alternative embodiment, the LED and the cooling device are manufactured together using micro processes or further alternatively using nanotechnology processes. In a preferred embodiment, the micro or nano manufacturing produces a layered LED/cooling device structure. The present invention, however, is not limited by the method of thermally coupling the LED die 105 to the cooling device 110.
The LED driver 115 is a typical LED driver. The power supply 120 is configured to supply a predetermined fixed current 125 to the cooling device 110. In a first embodiment of the invention, the fixed current 125 is based on typical junction temperature of the LED. In another embodiment, the fixed current 125 is based on typical usage and design of the lamp in which the LED unit 100 operates. Example applications of a lamp according to the present embodiment are a street lamp, parking lot lamp and a parking structure lamp. Accordingly, typical usage factors include weather factors and other environmental factors as well as lamp design. Another factor that may be used in determining the fixed current is average ambient temperature around the lamp in operation.
In operation, the LED die 105 emits light in response to the LED driver 115 which are both powered by the power supply 120. The cooling device 110 is supplied with a fixed current 125 by the power supply 120 and operates to cool the LED die 105. Operating the cooling device 110 at the fixed current 125 enables the unit 100 to operate without a controller thereby realizing both a cost savings and a form factor benefit in saving space that would be otherwise occupied by housing a controller.
In operation, the LED die 170 emits light and generates heat. The thermoelectric cooler 175 takes DC current as input and transfers heat from the LED die coupling to the heat sink coupling thereby removing heat from the LED die 170. The heat sink 180 dissipates heat passively. At least some of the heat from the heat sink 180 is transferred to the thermoelectric generator 185. The thermoelectric generator 185 generates a DC current. The DC current is received by the thermoelectric cooler 175 and is a portion of the energy needed for the operation of the thermoelectric cooler 175. The thermoelectric cooler 185 thus provides additional cooling that enables the heat sink 180 to be reduced in size over a heat sink needed in a configuration without the thermoelectric cooler 175.
In a first arrangement, the LED modules 200 are physically and electrically coupled into the lamp 400 through the substrates 410, the substrates 410 providing conductive connections. In an alternative arrangement, the LED modules 200 are physically coupled to the substrates 410 but electrically coupled though connections between the LED modules 200. In one embodiment, the LED modules 200 have covers as described above with regard to
In operation, the LEDs 502 provide light and generate heat. The thermo coolers 504 are powered electrically and draw heat away from the LEDs 502. The heat sink 506 provides further heat spreading and dissipation. Some of the heat flows from the LEDs generating heat across the heat sink 506 and up the fins to the thermo generators 508. The thermo generators 508 generate electrical power from heat from the heat sink 506. This electrical power is provided to the thermo coolers 504 as a portion of the power needed for their operation.
In operation, the LED 520 generates heat, some of which flows to the heat sink 522. The thermo generators 524, which are in thermal contact with the heat sink 522, generate electrical current from heat received from the heat sink 522. The current flows through the cables or PCB traces and is provided back to LED(s) 520 as a portion of current needed for their normal operation.
In operation, the LED 560 generates heat some of which flows to the active cooler 562. Some of the generated heat flows to the heat sink 564. The thermo generators 566, which are in thermal contact with the heat sink 564, generate electrical current from heat received from the heat sink 564. The current flows through the cables 568 and is provided to the active cooler 562. Since the active cooler 562 pumps heat away from the LED(s) 560, which are sources of heat, and the graphite heat sink is typically more efficient in thermal conductivity than aluminum, and the thermo generators provide some of the power for the active coolers, the cooling system of the present embodiment is typically smaller and lighter in weight than conventional cooling systems. The cooling system is typically more efficient in heat management and accordingly the LEDs can be operated at higher power while maintaining longevity. Further, the cylindrical shape of the heat sink in
Some graphite materials suitable for use in thermal management have good x, y thermal conductivity, but poor z direction thermal conductivity. In the present embodiment, the graphite in the graphite pad 615 is oriented to transfer heat to the heat sink 620. The heat sink 620 is typically selected to have good thermal conductivity in the x, y and z direction. The arrangement in this embodiment is efficient as it removes the heat from the LEDs and distributes the heat in the x and y directions rapidly. The heat sink with fins receives heat from the graphite pad and dissipates the heat to the air.
The power supply module 704 houses a power supply 706 that powers the light source modules 702 and an LED driver 714 to drive the LEDs in the light source modules 702. The power supply module 704 further includes sensors: a light sensor S1 to sense daylight and a motion sensor S2. One of the ordinary skill in the art will understand that other types of sensors are possible in alternative embodiments of the power supply module 704. The power supply module 704 further includes a controller 708. The controller 708 in one arrangement includes a timer. In another arrangement, the controller includes a dimmer. The sensors S1 and S2 and controller 708 increase the energy efficiency of the fixture 700. In one alternative embodiment, the controller 708 is programmable enabling a user to provide on-off settings and establish thresholds for lamp operation. In operation, the controller 708 responds to sensor data to turn the lamp on or off (or alternatively to dim the lamp) when the sensors do not detect movement in the room or detect that the light level, from windows for example, is sufficient. In those embodiments where a timer is present, the controller operates the lamp according to timed thresholds and periods. In an alternative embodiment of the power supply module 704, one of the sensors, for example S1, is instead a transceiver operable in a radio frequency network such as a ZigBee network. In this embodiment, the controller 708 further operates to respond to transceiver signals in operating the lamp. This operation is described in greater detail below with regard to
Embodiments of the housing of the power supply module 704 include a mesh screen as one side of the housing (shown in subsequent figures). The screen enables air to flow through the power supply module 704. In one embodiment, the housing has openings on the sides to enable air flow also through the light source modules 702. This air flow cools the power supply 706 and the LEDs in operation. The power supply 706 is preferably sized and configured such that there are spaced between the power supply and all four walls of the power supply module housing so that there is air flow fully around the power supply thereby passively cooling the power supply module 704.
The light source modules 702 are formed and configured such that they can be attached at the ends of the power supply module 704 or at the sides of the power supply module 704. This is described below and illustrated in subsequent figures. Further, the light source modules 702 are configured to be easily removed and replaced thereby making maintenance and serviceability of the lamp 700 easier. In some embodiments, the light source modules 702 are tiltable in order to direct the light generated by the light source modules 702 as desired. In various embodiments of the light source modules 702, thermal management is accomplished using one of the cooling arrangements described above. Some embodiments of the light source modules 702 hold arrays of LED modules as described above. In these embodiments, the LED modules are replaceable generally making these embodiments more cost effective to maintain and repair.
In some embodiments of the fixture, the light source modules and power supply module are of similar size and shape and configured to assemble interchangeable and rearrangably. One advantage of this is aesthetic as the user can create a lamp according to a desired shape. Another advantage is that a lamp fixture can be assembled to direct light where it is needed. The modules are also replaceable which provides the advantage of easy and typically less expensive repair and typically less expensive maintenance compared to conventional lamps. In some embodiments, the modules are of compatible size and shape and retain the advantages of rearrangability and replacability. Finally, separate housing of the light sources and power supply provides an advantage to thermal management. First, the heat generating elements are distributed rather than concentrated in a single housing. Second, the module has only one type of heat generating element. Therefore, a cooling system most efficient for that element can be used. These advantages will be evident in the descriptions of embodiments below.
The top and bottom 754 of the power supply module 750 have openings that enable air to flow into and out of the module 750 for passive cooling of the power supply module 750. In the present embodiment, the bottom 754 of the module 750 is a screen 756 that enables air to flow into the module 750. The module 750 further includes sensors 758 as described above with regard to
The modules 750, 802 are elongated, narrow in one dimension and relatively long in another. The modules 750, 802 in the present lamp 800 are connected at narrow ends thereby forming an elongated lamp structure. The modules 750, 802 in a first arrangement are connected by means of brackets. Other connection means in other arrangements include screws, brackets, brackets with screws, mating slots, clamps, and plugs and receiving elements. One skilled in the art will recognize that the present invention is not limited to the mechanical connection methods listed here. In an alternative embodiment, the electronic connection between modules is combined with the mechanical connection.
Each of the modules 750, 802 is replaceable. Accordingly if one of the light source modules 802 or the power supply module 750 fails, the lamp 800 is easily repaired by replacing the failed module. Further, separation of heat generating elements in the modular lamp 800 into different modules, that is, locating LEDs in one module and the power supply in another module, improves thermal management. One reason that this arrangement is advantageous to cooling is that this arrangement prevents the additive heating that would occur if the LEDs and the power supply were in the same housing.
The lamp assembly 950 is mounted in place using railings. The right railing 988 is located at the upper right corner of the housing 952. The left railing is not seen in this view. In one arrangement, the housing 952 is mounted by sliding the housing horizontally along the railing which has a supporting portion to hold the housing in the railing. In another embodiment, one side of the housing 952 is hooked on one railing and the housing is then rotated upward to the other railing and pressed in to place. This method of mounting will be illustrated and described in further detail.
The housing 952 holds a plurality of light sources such as light emitting diodes (LEDs) arranged in LED modules. The modules are mounted in several panels 978, 980, 982, where each LED is located behind a lens 976. The panels 978, 980 and 982 are part of a frame 990 holding LED modules. The frame 990 is reflective. Each panel 978, 980, 982 of the frame 990 includes at least two angled extensions that are reflective. The frame 990 is made of aluminum, for example, that is polished on one side. The center panel 980 is substantially parallel to the housing bottom 954. The left panel 978 and right panel 982 are angled outward toward the left and right sides of the housing 952 respectively. Many LEDs emit highly directional light with peak luminous intensity normal to the surface of the LED. The angled panels increase the field of light emission from the lamp assembly. Further, the LEDs in the left panel 978 and right panel 982 are arranged with sufficient spacing from the left and right sides of the housing such that light emitted through the opening in the lamp bottom is maximized. The lens 976 that covers each LED further diffuses the LED light. The benefits of the angled panels can be seen particularly when the lamp assembly is used to illuminate aisles such as those found in stores and warehouses or used to illuminate parking structures or parking lots.
The lamp cover 984 in the housing bottom 954 is, in a first arrangement, made of glass. In alternative arrangements, the lamp cover 984 is made of plastic. The lamp cover 984 protects the LEDs modules mounted in the lamp assembly from dust and the elements, such as rain. The lamp cover 984 is set into the housing so that it can be readily removed and replaced. In one arrangement, the lamp cover 984 is set in to the large opening 966 of the housing 952 by means of a gasket that enables the cover 984 to be readily pulled out and replaced for servicing of the lamp assembly. This enables the lamp assembly to be serviced in the field. The lamp cover in one alternative embodiment includes a heating element to de-fog or de-ice the lamp cover 984 in inclement weather. The heating element typically takes heat generated by the LEDs. The lamp cover 984 and its setting into the housing will be described in greater detail below.
The lamp assembly 950 includes elements that enable light from the LED modules to be directed upward from the lamp assembly as well as downward. The LEDs in the lamp assembly 950 are directed substantially in a primary direction of illumination, which in this embodiment is downward. The angle of the light emitted by the LED modules is increased by setting some of the LED modules at an angle as described above. Extensions on the panels of the frame further distribute the light intensity in the downward direction. Some of this emitted light, however, is directed toward the flanges 970, 972. At least the lower portion of each flange has a reflective inner surface. Light is reflected by this reflective inner surface upward, in a secondary direction of illumination. The redirected light passes through the windows 994 in the flanges 970, 972. This light illuminates the space above the lamp assembly 950. Lamps that have strongly directed light such as LED lamps tend to create what is referred to as “the cave effect” where the ceiling of the lighted space is obscured in darkness above the lamp. The present lamp assembly with the upwardly directed light tends to avoid the cave effect.
The frame 990 has a left panel 978, a center panel 980 and a right panel 982. The left panel 978 and right panel 982 are angled outward away from the center panel 980. Each panel 978, 980, 982 has two or more angled extensions 996. Each extension 996 is angled generally toward the panel to which it is attached. LEDs tend to emit very directed light and the angled panels and extensions increase the angle of light emission from the lamp assembly. The reflective surfaces reflect light away from the frame.
Each panel 978, 980, 982 has a plurality of openings 998. At least one LED module is positioned on each panel 978, 980, 982 of the frame 990 where at least one LED is positioned over each opening 998 in the frame 990. Typically, for maintenance or repair, the LED modules are removed and replaced as needed.
The inner surfaces 1006, 1008 of each flange 970, 972 are seen in this view. The inner surfaces 1006, 1008 are reflective. In the lamp assembly in operation, light from the LED modules is reflected from the inner surfaces 1006, 1008 through the windows 994 in the flanges. This provides an upward directed light that enables the lamp assembly to avoid creating a cave effect in the space the lamp assembly illuminates.
The lamp cover 984 further includes a heat element 1012. The heat element 1012 in a first embodiment is connected to the LED modules as described above and conducts heat from those modules to the lamp cover 984. The heat element 1012 warms the lamp cover 1012 for de-fogging or de-icing purposes. In an alternative embodiment, covers in the flange windows also include heating elements.
In mounting the lamp assembly 950 at a location, the top cover 1014 is set in place first. The lamp assembly 950 is then mounted into the top cover 1014 by first engaging the railing on the right side of the lamp assembly 950 with the right side of the top cover 1014. The bent edge and railing form a hinge. The lamp assembly 950 is rotated upward until it is in place to engage with the left side of the top cover. The left side 1016 opens to receive the lamp assembly 950 and the bent edge of the left side 1016 is engaged with the railing on the left side of the lamp assembly 950. The left side is then secured in place with nuts threaded over the ends of the rods 1024, 1026.
The hinged assembly enables partial engagement with the top cover as shown. This allows for wiring and other installation steps to be performed easily before finishing the installation by lifting the lamp assembly into final position.
Solid state lamps according to embodiments of the invention are energy efficient both through the use of low-energy consumption light sources but also through the passive cooling of the design as well as through the sensors and controller that govern operation of the lamp such that light is provided when needed. The fixtures may be turned off or dimmed when light is not needed. Accordingly, the lamp assemblies are useful in energy efficient lighting systems as in the system described below with regard to
The lighting system shown in
In operation, the lamps 1110 sense the proximity of the worker 1135 based on the signal strength of the signal from the badge 1140. The lamps sensing a signal communicate with other lamps nearby in the mesh network to alert those lamps to the presence of a badge. If the controller in a lamp determines that it is within range of illumination, that is, within the outer circle but not the inner circle, then the controller operates the lamp at 35% power. If the controller in the lamp determines that the lamp is within the inner circle of proximity, then the controller operates the lamp at 100% power. As the worker moves about the space 1105, the controllers in the lamps respond by increasing or decreasing their power levels to provide more or less illumination. If there are multiple workers in the warehouse, the lamps respond equivalently. As the workers move about, those lamps falling within the outer circles of proximity around each worker turn up to a higher level of illumination and the lamps falling within the inner circles turn up to a higher level still of illumination. In a first embodiment, the level of illumination remains substantially constant as long as a lamp senses a proximate badge. In this way, the present system is advantageous over motion detector systems in that the lamps continue to provide light, that is, stay “on”, even if the worker or workers in the area are stationary for prolonged periods of time. In an alternative embodiment, the controller, using its timer, remains at a constant level of power for some period of time after all badges leave the area of proximity. The period of time is for example 1 to 2 minutes.
The transceiver, controller and LEDs of LED lamps together make the lamps low latency devices able to respond quickly to the badge signals. Accordingly, the lighting system of the present embodiment is generally faster in its response time than conventional motion detector systems. Additionally, a radio-frequency system is advantageous over systems having line-of-sight sensors in settings like a warehouse because the line of sight may be blocked.
Further through the Internet connection, the lighting system may be monitored, controlled or reprogrammed remotely. The controller in each lamp is responsive to external control information received from the master controller or received through the Internet connection. The master controller, connected to the Internet, enables a user such as a building manager to control the lighting system remotely. Further, the master controller is able to collect data from the lamps in the lighting system. The Internet connection enables the lighting system to be observed remotely. In one embodiment, the lighting system is part of an electric utility's demand response system. The master controller receives signals from the electric utility regarding demand. The master controller then operates the lighting system in response to the demand signals. Participation in utility demand response programs typically lowers power costs for the customer.
At step 1205, the lamp controller determines from the received badge-generated signal or signals and from the alerts from other lamps whether there is a badge in proximity to the lamp. If there is no badge within lighting range, the lamp controller proceeds to step 1210. If there is a badge within range, the lamp controller proceeds to step 1215.
At step 1210, the lamp controller keeps the lamp at low power because there are no badges in proximity to it. The default low power level for the lamp in the example implementation provided above is at 10% power. The lamp controller also sends information through the transceiver to other lamps in the network that there are no badges and also, in some embodiments, forwards information received from other lamps regarding badge location. The lamp then returns to step 1200.
At step 1215, the lamp controller has determined that a badge is proximate to the lamp. In this step, the lamp controller determines whether the badge is close by, that is, whether the lamp is within the inner circle of proximity or only the outer circle of proximity around the badge. That is, the lamp controller determines whether a badge has crossed one of the proximate thresholds and then proceeds to determine which threshold. If the lamp is not within the inner circle of proximity, the controller proceeds to step 1220. If the lamp is within the inner circle of proximity, then the controller proceeds to step 1225.
At step 1220, the lamp controller, having determined that the lamp is inside the outer circle of proximity around at least one badge, operates the lamp at 35% power. The lamp sends an alert over the network that there is at least one badge in proximity. The lamp then returns to step 1200.
At step 1225, the lamp controller, having determined that the lamp is inside the inner circle of proximity around at least one badge, operates the lamp at 100% power. The lamp sends an alert over the network that there is at least one badge in proximity. The lamp then returns to step 1200.
It is to be understood that the above-identified embodiments are simply illustrative of the principles of the invention. Various and other modifications and changes may be made by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.
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| Child | 14848067 | US |
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| Child | 13410158 | US | |
| Parent | 12454532 | May 2009 | US |
| Child | 12592563 | US |
