Abstract:
A lighting control module for controlling power to a lamp is presented. The lighting control module comprises a receiver for receiving electronic communications from a central controller, a current sensor, a current controller for controlling current in a power circuit passing through the module, the current controller operating to open and close the power circuit, a control unit connected to the current controller and the receiver, the control unit operating to cause the current controller to open and close the power circuit in response to the communications, and an indicator connected to the control unit. The control unit causes the indicator to illuminate when the current sensor indicates that current fails to flow in the power circuit when the current controller is operated to close the power circuit.

Description:
BACKGROUND OF INVENTION 
     This invention relates generally to lighting systems and, more specifically, to industrial lighting and high end commercial lighting control systems and a method therefor. 
     Industrial lighting and high end commercial lighting will be commonly referred to herein as “industrial lighting.” The traditional approach for providing industrial lighting to large areas, such as arenas, parking lots, and conference rooms, is shown schematically in FIG.  1 . Lighting system  10  includes a switch  12 , which may be a wall switch as shown or an activation switch. Switch  12  provides a control current to one or more lighting panels  14 . Only one lighting panel  14  is shown for purposes of illustration, though there may be any number of panel boards. Main power line  18  feeds power to a main contactor  11 , which may be a main circuit breaker. Main contactor  11  feeds power to a number of branch contactors  15  located within lighting panel  14 . Contactors  15  may include simple relays, dimmers, and/or remote-controlled circuit breakers. Each contactor  15  controls current to a branch circuit  22 , which provides power to a plurality of light fixtures  20 . 
     The lighting contactor system is activated when switch  12  is turned on sending a control current to contactors  15  via wiring  16 . Contactors  15  close the power circuit in response to receiving the control current from switch  12 , allowing electrical power to flow to fixtures  20  via branch circuits  22 . If a dimmer is incorporated into contactors  15 , then the power may be regulated by it. 
     Current industrial lighting contactor systems as described above possess several electro-mechanical problems. Because most light fixtures draw an increased amount of current while warming up, the main contactor experiences large current surges at the instant of closure. Moreover, high in-rush currents, high induced EMF&#39;s, and the like can reduce their expected service life by eroding the contact surfaces. 
     Additional problems stem from the centralized wiring systems currently employed. To provide the necessary current to operate heavy industrial loads such as in lighting auditoriums, stadiums, factories, etc. heavy wiring must be routed through a central location where the lighting contactors are installed. In such situations, lighting contactors are prone to produce an unpleasant and disruptive electrical hum and/or vibration caused by the high concentration of current. Furthermore, in these highly centralized systems, if a contactor fails, all of the lights that it controls will be rendered inoperative. 
     Conventional industrial lighting systems have furthermore not adequately met the needs of their users. For instance, conventional industrial lighting systems have no means of collecting and displaying wear data on the system, so that maintenance personnel can anticipate problems, such as a contactor failure or wearout, lamp failure or wearout, or other problem before it occurs. Furthermore, there is no system in place to remotely detect lamp failures. 
     For the past decade a number of companies have marketed residential lighting control systems comprised of wall switches, wall outlets, and various other devices equipped with electronics. These products have enabled a residential or low-end commercial user to remotely switch multiple lamps and other loads via a control panel. Traditionally, the communication technology for this type of application has been through hard-wired networks, RF communications and power line based communications. 
     However, conventional residential lighting systems have not addressed the issues discussed above with respect to industrial lighting. In particular, conventional residential lighting systems do not provide a means to monitor the usage for lamps and other loads. Furthermore, conventional residential lighting systems are not designed to alert the user of lamp failures, nor do they address the problems of rapid surges and sudden voltage drops that can occur when a large lighting system is energized. 
     What is needed is a functional replacement and enhancement to conventional technology that reduces power surge problems, provides sensing capability for determining defective lamps, decentralizes lighting contactors, and operates despite single point failures. 
     SUMMARY OF INVENTION 
     The above discussed and other drawbacks and deficiencies are overcome and alleviated by a lighting system that includes a plurality of lighting control modules for controlling power to a respective lamp. Each module comprises a signal receiving means for receiving electronic communications from a controller, a current sensor, a current controller for controlling current in a power circuit passing through said module, said current controller operating to open and close said power circuit, a control unit connected to said current controller and said signal receiving means, said electronics operating to cause said current controller to open and close said power circuit in response to said communications from said signal receiving means, and an indicator connected to said electronics, said electronics causing said indicator to illuminate when said current sensor indicates that current fails to flow in said power circuit when said current controller is operated to close said lower circuit. 
     The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     Referring to the exemplary drawings wherein like elements are numbered alike in the several Figures: 
     FIG. 1 is a schematic diagram of a light control and dimmer system using a high-amperage lighting contactor consistent with the prior art; 
     FIG. 2 is schematic diagram of a multiple integrated light control using light fixture modules; 
     FIG. 3 is light fixture module with a LED indicator; and 
     FIG. 4 is light fixture module with an electronic light dimmer. 
     FIG. 5 is a flow chart of an exemplary process in accordance with an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 2 shows a simplified schematic diagram of a lighting control system  50 . Main power line  18 , which may be a conventional 3-wire 220V AC power line, feeds into main contactor  11  and one or more branch circuit breakers  55 , each controlling a 110V AC branch circuit, as is well known. For simplicity, FIG. 2 does not show the separate phases, ground, and neutral lines. Each branch circuit breaker provides power to one or more modules  60 , module-fixtures  62 , or combinations thereof. Modules  60  control power to associated fixtures  20 . Other electric loads, such as ventilation fans, air conditioners, heaters, other environmental equipment, or other equipment in general can be connected to modules  60  as well. Fixtures  20  and module-fixtures  62  operate on 110V AC power. However, it should be understood that the invention is equally applicable to systems using different voltages. 
     As shown in FIG. 2, module-fixtures  62  can be used interchangeably with modules  60  each having a fixture  20  attached to it. Also, modules  60  and module-fixtures  62  can control a fixture  20  and any number of additional, auxiliary fixtures  21  by connecting them in parallel with fixture  20 . For each module  60 , the fixture  20  and auxiliary fixtures  21  are turned on or off or are dimmed together. Likewise, for each module-fixture  62 , the lamp connected to the module-fixture  62  and auxiliary fixtures  21  connected to it are also turned on or off or are dimmed together. It is also possible to provide a module or module-fixture with multiple independently-controlled outputs as in multi-module  63 , which is shown as having to fixtures connected to separate outputs thereof in FIG.  2 . The dashed lines in FIG. 2 represent that any selected number of branch circuits form the lighting system, any number of modules can be positioned on each branch circuit, depending, of course, on the current limitations of the circuit, and any number of fixtures can be connected to and controlled by each module, again, depending on the current limitations of the circuit. 
     Modules  60  and module-fixtures  62  are in communication with a controller  52 . Communication is achieved by radio, e.g., via antenna  53 , or by signal connection  54  to branch circuits  22 . In the latter case, communication is achieved by transmitting high-frequency signals through branch circuits  22  in the well-known manner. For example, the communications may be made over ordinary power lines using the CEBus™ protocol standard that is promulgated by the Electronics Industries Association. In addition to these preferred methods, communication may be established over other known mediums including twisted pair (telephone), coaxial cable, fiber optics, and infrared. As is known, these methods may be augmented by interfacing computer networks, such as a campus-wide, wide-area network or even using an Internet interface. So, while the system is shown in FIG. 2 as being powered through a single main circuit breaker, there is no such limitation in actual practice. Using known electronic communications techniques, controller  52  is capable of controlling any number of modules positioned anywhere, whether on a single main power distribution circuit or not. 
     Controller  52  may be a dedicated wall-mounted switch, control console, or a general-purpose personal computer. The lighting control system  50  may include centralized or distributed useful-life monitoring and turn-on delay control. In the centralized model, the controller  52  tracks usage of each lamp corresponding to a respective module  60  or module-fixture  62  and individually delays the turn-on for each lamp attached thereto. In the distributed model, the controller  52  sends general ON, OFF, or DIM % commands to all modules  60  and module-fixtures  62 . Controller  52  may have the capability to individually address and separately control each module  60  and module-fixture  62 , but in many applications, such lighting for parking lots, factories, and warehouses, this functionality is not required. 
     FIGS. 3 and 4 show respectively a schematic diagram of a module  60  and a module-fixture  62 . Each module  60  and module-fixture  62  includes a control unit  70  in communication with controller  52 . For example, a signal processor  64  that is in communication with control unit  70  sends and receives signals sent through branch circuits  22  in the known manner. Control unit  70  is connected to current controller  65 , which may be a relay mechanism or dimmer such as are known. Current controller  65  controls the current to lamp  75 , which is either connected in a separate fixture  20  shown in FIG. 3 or is connected directly into module-fixture  62  as shown in FIG.  4 . Lamp  75  may be any type of commercially available light source, such as an incandescent lamp, mercury-vapor lamp, fluorescent lamp, or other discharge device. Any required additional electronic components required for lamp  75  such as ballasts or other current-regulating means are omitted from the drawings, as they do not form a part of the invention. For the embodiment shown in FIG. 3, such components would be connected between current controller  65  and lamp  75  either in a separate housing or located within or attached to fixture  20  as is known, or within module  60 . 
     The electronics package in each module  60  and module-fixture  62  includes a current sensor and power supply  61 . Current sensor and power supply  61  detects the current in line  27  leading to lamp  75  and provides electrical power to control unit  70  and other associated components in a known manner even when no power flows through line  27 . In an alternative embodiment, Current sensor and power supply  61  is a current transformer that senses current in line  27  and provides electricity to control unit  70  only when current is flowing in line  27 . In this case, control unit  70  includes a battery or other electricity storage device (not shown) to provide electricity even when lamp  75  is off. 
     Current sensor and power supply  61  can detect whether lamp  75  fails to generate a load when ordered to turn on and thus is defective or has died. In that case, an electronic message is sent out to controller  52  indicating a lamp failure and a visible indicator  68  is turned on. Indicator  68  may take the form of a light emitting diode, a mechanical flag, or equivalent. Indicator  68  remains on even after the lamps are turned off, e.g., when parking lot lamps are turned off during the day, to thereby alert maintenance personnel of the defective lamp. 
     Control unit  70  includes a number of other sensor inputs. Module  60  and module-fixture  62  contain a timer  77  with a range from, e.g., 0 to 10, or 0 to 100 thousands of operating hours. Timer  77  may count down from a number of hours before lamp  75  is due to be replaced, or count up from the time lamp  75  was replaced to an expected number of hours of operation of lamp  75 . Timer  77  may, for example, be a turn-wheel. In this case, the electrician installing lamp  75  will reset the timer to indicate the number of hours of operation before the next replacement is scheduled, e.g., the expected life of lamp  75 , if timer  77  is a count-down timer. If timer  77  is a count-up timer, then the maintenance person will reset timer  77  to zero and ensure that an alarm setting is set to the number of hours of operation before the next replacement is scheduled. 
     When the lamp is turned on, control unit  70  operates timer  77  to slowly rotate the turn-wheel towards zero, if timer  77  is a count-down timer, or slowly rotate the turn-wheel away from zero, if the timer  77  is a count-up timer. In this way, timer  77  operates to indicate the remaining hours-of-operation of the connected lamp  75  before replacement is due. When timer  77  reaches zero or the selected alarm value, indicator  68  will illuminate, indicating that the replacement is due for lamp  75 . 
     The function of timer  77  may be implemented either completely electronically, or electro-mechanically, as would be appreciated by a skilled artisan. It is also contemplated that timer  77 , while preferably implemented as a turn-wheel as shown in FIGS. 3 and 4 due to its simplicity of operation, may be replaced with a digital interface, with the timing and indicating function performed by software within control unit  70  and a digital display (not shown). 
     Module  60  and module-fixture  62  also include a turn-on delay timer  79 . The turn-on delay timer  79  includes settings from instantaneous to several seconds. For some lamp types having long warm-up times, the possible settings may be even greater. Turn-on delay timer  79  may also include a random setting, which allows control unit  70  to select a random turn-on delay. Selecting a variety of turn-on delays for all the fixtures in a lighting system will eliminate the current surge/voltage drop caused by a large number of lamps being turned on simultaneously. 
     In some outdoor installations, module  60  and module-fixture  62  may include a photo-sensor  66  to detect ambient light conditions. In this case, when control unit  70  receives an “on when dark” command, it will control current controller  65  to turn on lamp  75  only when there is insufficient ambient light available. For example, when the ambient light level drops to a first threshold, control unit  70  will turn on lamp  75 , and when the ambient light reaches a second threshold higher then the first threshold, the control unit  70  will turn off lamp  75 . Although not required, the use of two thresholds reduces flickering. 
     Alternatively, only one or several of modules  60  or module-fixtures  62  include a photo-sensor  66 , and control unit  70  thereof is periodically queried by controller  52  as to the current level of ambient light. Upon receiving this query, control unit  70  responds by sending a signal to controller  52  indicating the current ambient light level. When the ambient light reaches a user-selected lower threshold, controller  52  sends a signal to all modules  60  and/or module-fixtures  62  to turn on lamps  75 . Querying several modules  60  and/or module-fixtures  62  will provide redundancy in case one of the photo-sensors malfunctions or becomes covered with debris. 
     Infrared (IR) transceiver  82  may be provided in each module  60  and module-fixture  62  for allowing communication between control unit  70  within the modules  60  and module-fixtures  62  and a hand-held controller device (not shown). There are many potential uses for IR transceiver  82 . For example, a single hand-held controller may replace timer  77  and separate turn-on delay  79  in each module  60  or module-fixture  62 , and all the functions are handled instead through the hand-held control device, which may be a hand-held computer such as a dedicated device or a Palm Pilot™, WindowsCE™ device, or equivalent, equipped with a standard IR interface and software allowing it to interact with control unit  70 . Thus, by simply pointing the hand-held device to a light fixture, communication can be thereby established, and information as to the maintenance can be downloaded to the hand-held device, and instructions can be transmitted to control unit  70 , including ON or OFF commands, as well as setting the turn-on delay and hours-of-operation of lamp  75 . IR transceiver  82  may be disposed in a separate housing (not shown) and mounted adjacent to fixture  20  or module-fixture  62  in situations where a reflector (not shown) of the light fixture would otherwise block a line-of-sight to IR transceiver  82 . This could be a solution in warehouse and factory lighting applications where large reflectors are sometimes employed. 
     IR transceiver  82  can also be used as a means of communicating with controller  52 , which may be useful if the module or module-fixture is connected to a completely different circuit and thus cannot communicate via branch circuit  22 . 
     The above description relates to a distributed model of monitoring lamp life and controlling turn-on delay. In an embodiment employing a centralized model, the functions described above are performed by controller  52  in a central or remote location by a control console or a general-purpose computer as previously described. In this model, controller  52  maintains a database or list of each module  60  and/or module-fixture  62  with associated hours-of-operation data and turn-on data of connected lamps  75 . With regard to the hours-of-operation, information is input into controller  52  when a lamp replacement is made, and the expected hours of operation of the replacement lamp. This input can be done manually by a technician at the time of lamp replacement, or automatically. For example, module-fixture  62  may include a lamp sensor  85  having a plunger-switch to detect the removal of lamp  75 . 
     Other means of detecting the removal of lamp  75  are contemplated, such as an optical sensor or magnetic sensor disposed in the lamp base. Alternatively, control unit  70  of either a module  60  or module-fixture  62  may perform a periodic continuity check on lamp  75 . When the continuity is broken, that is an indication that the lamp is either removed or burned-out. This technique has the advantage that it will work with conventional fixtures, e.g., fixture  20 . Other types of sensors may be used as well, as would occur to the skilled artisan. 
     Regardless as to the type of sensor employed, when it detects that lamp  75  is replaced, it sends a signal to control unit  70 , which sends a signal to controller  52 . Controller  52  identifies the address of the module-fixture  62  that sent the signal, and responds by resetting the hours-of-operation data for that fixture to the selected amount. 
     The controller automatically and periodically decrements the hours-of-operation remaining for each lamp  75  that that lamp is on. For example, every hour, controller  52  may check which lamps are on, and decrement the hours-of-operation data for those lamps by one. Alternatively, controller  52  may track the minutes or other fractions of an hour, such as tenths of an hour (i.e., six-minute increments), of operation for each lamp, and sum the total as a fraction of hours. When the hours-of-operation data reaches zero for any one module  60  or module-fixture  62 , a signal is sent to that module  60  or module-fixture  62  causing it to illuminate its indicator  68 , thereby informing maintenance personnel that the connected lamp  75  is due to be replaced. 
     Similarly, when a lamp  75  fails to generate a load, control unit  70  senses this and sends a signal to controller  52 , indicating that the lamp is no longer functioning. 
     Controller  52  then sends a signal back to that module  60  or module-fixture  62 , causing it to illuminate its indicator  68 . In addition, controller  52  informs the operator that the lamp no longer functions, and may provide a graphic or other indication as to the location of the non-functioning lamp. 
     To turn on the lamps in lighting control system  50 , the operator simply inputs the instruction into controller  52 . This input may take the form of flipping a switch from “OFF” to “ON”, or pressing an “ON” button, or interacting with a software program on a computer, in any known manner. For example, a graphical-user interface or other interface can allow the operator to select specific lamps, or every-other lamp, every 10 th  lamp, or other predetermined groupings of lamps. In some environments, such as a conference center, having individual control over each lamp is very advantageous. In this case, a map of the conference center can be displayed on a computer screen showing the location of each lamp, and each lamp can be individually controlled simply by selecting it and entering a command via a pop-up menu or the like. Individual lamps may be selected by simply clicking the representation on the screen of the lamp, and multiple lamps can be selected by dragging a box around the lamps to be turned on off, or dimmed. 
     Upon receiving the operator&#39;s input instruction for turning on a large number of lamps, controller  52  delays turning on each selected lamp by the amount recorded in its database. FIG. 5 shows a flow chart describing an exemplary process for delaying the start-up time for each lamp. 
     After starting at box  102  the controller immediately proceeds to box  104  where the controller  52  waits for an ON command for selected lamps by loop  105 . After an ON command is inputted into controller  52 , controller  52  proceeds to box  106  where the time counter variable is initialized to zero. Then, at box  108 , the controller compares the time counter with the turn-on delay value for each selected light fixture. For those selected light fixtures having a turn-on delay that is equal to the value of the time counter, an “ON” command is transmitted to the corresponding modules  60  and/or module-fixtures  62 . Controller  52  then proceeds to box  110  wherein a check is performed as to whether all the selected lamps are turned on. If not, the controller proceeds to box  112  and waits for the next clock tick. Clock ticks can be every 10 th  of a second or otherwise, depending upon the application. Transmission of “ON” commands in box  108  may be processed in parallel, to ensure that each clock tick is counted. When the next clock tick is received, controller  52  proceeds to box  114  wherein the time counter is incremented by the appropriate amount. Controller  52  thereafter returns to box  108  and continues as before. 
     If the controller reaches box  110  and all selected lamps have been turned on, the controller exits the turn-on delay loop and proceeds to box  120  where the procedure is ended. The turn-on delay data stored in controller  52  may be manually input into controller  52  or the operator can select the time spread for the lamps and instruct controller  52  to automatically select turn-on delays either sequentially or randomly. Alternatively, the operator can simply input the type of lamps used and allow the controller  52 , using stored data, to select optimum start-up timings for the lamps in lighting control system  50 . The start-up timings will depend on the warm-up time for the type of lamps installed, and limit the total number of lamps warming up at any one time to a selected number of lamps. 
     While preferred embodiments have been shown and described various modifications and substitutions may be made thereto without departing from the spirit limitation and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limited to the illustrative embodiments.