Abstract:
In accordance with aspects of the present disclosure, a system and method of controlling the internal environment of an enclosure is provided. The system and method includes either increasing or decreasing the temperature of the enclosure to a predetermined target under normal operating conditions. The system and method further includes selectively engaging a trip condition in response to an overheat limit temperature. During the trip condition, the power relays for the fixture will be opened until the enclosure internal temperature has dropped. The system and method uses various sensors to control environmental conditions and may be controlled remotely.

Description:
BACKGROUND 
       [0001]    Video projectors, conventional lighting units, moving lights, laser projectors, and other luminaires (collectively “lighting fixture” or “fixture”) include components and materials which are sensitive to variations in environment, including: temperature, humidity, moisture, precipitation, electrical discharge, impact, and vibration. Lighting fixtures generally include rudimentary means of controlling excessively high temperature by using one or more cooling fans, where the fan duty cycles are directly related to measured temperature within the lighting fixture and normally emit noise that can be perceived by people and recording equipment in proximity with the unit. Typically, lighting fixtures do not have the means to directly control humidity and moisture, which can increase the risk of corrosion and other types of damage to the internal components. The danger of corrosion directly limits the locations in which they may be utilized, such as outdoors, humid environments, or anywhere near water. 
         [0002]    Lighting fixtures are widely used in locations where quiet operation is an advantage, such as lecture halls, auditoriums, houses of worship, and movie sets. Some applications require dismantling the lighting fixture and moving some component to other areas where the noise is not bothersome. This limits the durability and efficiency of the lighting fixture and is often not practical. 
         [0003]    A separate enclosure can be used in conjunction with the lighting fixture to protect against temperature, humidity, precipitation, and other environmental stress. In addition, the enclosure can reduce the noise created by the lighting fixture. Finally, the enclosure can control the internal temperature in order to maintain ideal operating conditions for the projector unit, regardless of the surrounding environment. 
         [0004]    Enclosure environment controls are known in general, what is needed is a system that is configured to respond to parameters other than by direct reaction to internal temperature. This system needs to consider humidity, temperature, power usage, user-defined limits, and duty cycles when determining a control strategy. 
       SUMMARY 
       [0005]    In accordance with aspects of the present disclosure, a system and method of controlling the internal environment of an enclosure is provided. The system and method can control the environment by increasing or decreasing the temperature of the enclosure to a predetermined target under normal operating conditions utilizing at least one fan and at least one heater based upon criteria mostly comprising temperature and humidity measurements. The system and method further includes selectively engaging a trip condition in response to an overheat limit temperature. During the trip condition, the power relays for the enclosure will be opened until the enclosure internal temperature has dropped. The system and method may also be controlled by a remote data communication. The system and method can further include at least one fan for stirring the air within the enclosure. The system and method further comprises the duty cycle calculation for determining the duration and interval of each heater and fan operation. 
         [0006]    One embodiment of the system for controlling the enclosure environment comprises a temperature measurement and a relative humidity measurement and utilizes user-configurable temperature and humidity limits to activate a heater to adjust relative humidity and a fan to adjust temperature when factoring in the heater duty cycle and fan duty cycle. This system may also limit power to the enclosed lighting fixture in order to reduce internal enclosure temperature. One preferred power limitation length of time is at least four minutes. 
         [0007]    The embodiment may further comprise a user-configurable maximum power draw of the system and the contained lighting fixture where the heater duty cycle is adjustable based upon total system power usage. The fan duty cycle may also be adjusted in order to reduce overall or intermittent noise. 
         [0008]    This embodiment may further comprise at least one additional fan for stirring the air within the enclosure designed to increase the temperature monitoring accuracy. 
         [0009]    Another embodiment of a method of controlling the internal environment of an enclosure comprises a plurality of sensors to determine a fan duty cycle to operate a fan and a heater duty cycle to operate a heater. This embodiment may further comprise determining either or both of the duty cycles based upon the enclosure internal temperature measurement and the user-configurable upper temperature limit. Alternatively, the system may determine either or both duty cycles based upon a calculated ideal temperature and relative humidity threshold. Finally, the system may determine either or both duty cycles based upon both the enclosure internal temperature measurement and the relative humidity measurement. The plurality of sensors are comprised of at least one temperature sensor, at least one relative humidity sensor, at lease one voltage sensor, and at least one amperage sensor. In this embodiment, either or both duty cycles may factor in data from the voltage sensor and the amperage sensor. 
         [0010]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing aspects and many of the attendant advantages of disclosed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0012]      FIG. 1  is a block diagram illustrating an embodiment of a method of controlling an internal enclosure environment according to various aspects of the present disclosure; 
           [0013]      FIG. 2  is a block diagram illustrating an embodiment of an enclosure and an environmental control system according to various aspects of the present disclosure; 
           [0014]      FIG. 3  is a graph that illustrates relative humidity values with respect to internal air volume temperature values as may be used by various embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The detailed description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended only as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result. 
         [0016]    Although the present disclosure is described hereinafter with reference to video projector units, it will be appreciated that aspects of the present disclosure have wide application, and therefore, may be suitable for use with many types of electronic units and/or illuminating device, such as conventional lighting fixtures, intelligent lighting fixtures, laser projectors, video cameras, audio equipment, computers, other luminaires, etc. Any applicable unit and/or device shall be referred to as “lighting fixture” in this disclosure. Accordingly, the following descriptions and illustrations herein should be considered illustrative in nature, and thus, not limiting the scope of the claimed subject matter. 
         [0017]    Prior to discussing the details of various aspects of the present disclosure, it should be understood that several sections of the following description are presented largely in terms of logic and operations that may be performed by conventional electronic components. These electronic components, which may be grouped in a single location or distributed over a wide area, generally include processors, memory, storage devices, display devices, input devices, etc. It will be appreciated by one skilled in the art that the logic described herein may be implemented in a variety of hardware, software, and combination hardware/software configurations, including but not limited to, analog circuitry, digital circuitry, processing units, and the like. In circumstances where the components are distributed, the components may be accessible to each other via communication links. 
         [0018]    In the following description, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that many embodiments of the present disclosure may be practiced without some or all of the specific details. In some instances, well-known process steps have not been described in detail in order not to obscure unnecessarily various aspects of the present disclosure. Furthermore, it will be appreciated the embodiments of the present disclosure may employ any of the features described herein. 
         [0019]      FIG. 1  is a block diagram illustrating an embodiment of a method of controlling an internal enclosure environment according to various aspects of the present disclosure. The present disclosure is included within an enclosure  100  designed to enclose a lighting fixture  128 . The lighting fixture  128  includes many features known to one of ordinary skill in the art as being included, such as a lamp, a lens, a body, a system controller, and so on. 
         [0020]    The illustrated enclosure  100  includes various sensors, including a temperature sensor  102 , a relative humidity sensor  104 , an amperage meter  106 , and a voltage meter  108 . The temperature sensor  102  determines the temperature of the volume of air within the enclosure  100 . The relative humidity sensor  104  determines the relative humidity of the volume of air within the enclosure  100 . The amperage meter  106  determines the electrical current draw of the lighting fixture  128 . The voltage meter  108  determines the electrical voltage of the lighting fixture  128 . The various sensors, described above, provide real-time inputs to the various sub-systems of the enclosure  100 . The inputs are required to monitor and maintain the internal environment of the enclosure  100  at the desired levels. 
         [0021]    The temperature sensor  102  provides the temperature of the volume of air within the enclosure  100  to a variety of sub-systems. It provides data to the minimum target temperature sub-system (MTT)  110 . The relative humidity sensor  104  provides the relative humidity of the volume of air within the enclosure  100  to the MTT  110 . The MTT  110  uses the data from the sensors to determine the minimum, or ideal, temperature that will be required to keep the relative humidity of the internal environment of the enclosure  100  within the requirement of the maximum allowed relative humidity, which is user defined, and the minimum enclosure internal temperature. The temperature sensor  102  also provides data to the fan temperature control sub-system (FTC)  112 . The FTC  112  is a system to cool the enclosure  100  proportionately when the enclosed temperature rises above the cooling threshold. The temperature sensor  102  also provides data to the heater temperature control sub-system (HTC)  114 . The HTC  114  is a system to maintain a minimum temperature as determined by the ideal temperature. 
         [0022]    The FTC  112  determines a required fan duty factor and provides the factor as an output to the fan duty cycle controller (FDC)  118 . The FDC  118  is a system to switch one or more fans on periodically according to the required duty cycle relayed by the FTC  112 . The FDC  118  output sends electrical power to the fan switch  124 . In some circumstance, such as use in noise sensitive areas such as theatrical or video production use, the FTC  112  may also be operated in a “Hush” mode designed to reduce noise levels by reducing FDC  118  interval and duration. The FTC  112  also has an output to the lighting fixture power relay  122 . The FTC  112  can open the power relay  122  to interrupt power to the lighting fixture  128  when the trip condition is engaged. In some embodiments, at least one fan is activated in order to maintain the temperature of the volume of air within the enclosure  100  below the upper temperature: a user-defined value. This is especially critical when the lighting fixture  128  is drawing substantial power and generating heat. This may be required when the temperature of the volume of air within the enclosure  100  exceeds the configurable Limit_Temp  310  where continued usage may cause damage to the lighting fixture or reduce useful lamp life. 
         [0023]    The HTC  114  determines a required heater duty factor and provides the factor as an output to the heater duty cycle controller (HDC)  120 . The HDC  120  is a system to switch one or more heaters on periodically according to the required duty cycle relayed by the HTC  114 . The HDC  120  output sends electrical power to the heater switch  126 . In some embodiments, at least one heater is activated in order to maintain the temperature of the volume of air within the enclosure  100  above the minimum temperature determined by the MTT  110 . This is especially critical when the lighting fixture  128  is not drawing power and the external air temperature is cooler than the minimum temperature determined by the MTT  110 . This prevents a variety of issues to the fixture caused by condensation and temperature changes such as circuitry oxidation, metal oxidation, environmental damage to optics, and changes caused by variability in material expansion and contraction. 
         [0024]    The amperage meter  106  determines the electrical current draw of the lighting fixture  128 . The amperage meter  106  provides data to the load power calculation sub-system (PWR)  116 . The purpose of the PWR  116  is to provide a real-time calculation of the electrical power drawn by the lighting fixture  128 . 
         [0025]    The voltage meter  108  determines the electrical voltage of the lighting fixture  128 . The voltage meter  108  provides data to the PWR  116  to enable the real-time calculation of the electrical power drawn by the lighting fixture  128 . The PWR  116  provides data to the FTC  112  to enable the FTC  112  to run the FDC  118  at a duty cycle proportional to the power drawn by the enclosed lighting fixture  128 . This is necessary to avoid sharp temperature spikes in the enclosure  100  during high power draw events. The PWR  116  provides data to the HTC  114  to run the HDC  120  at a duty cycle inversely proportional to the power drawn by the enclosed lighting fixture  128 . This is necessary to avoid excessive power draw by the enclosure  100  and maintain system stability. The PWR  116  also provides a signal directly to the HDC  120  to inhibit the heater operation should the lighting fixture power draw approach the maximum system power rating. 
         [0026]    A lighting fixture may be in a deactivated state, a standby state, or an active state where the lamp is active. The PWR  116  is able to determine the state of the fixture based upon data from the amperage meter  106  and the voltage meter  108 . In a deactivated state, the fixture draws no power. In a standby state, the lighting fixture draws power in the range of 0.2 amperes to 2 amperes. Amperage draw exceeding a user-configurable power draw within this range correlates with an active state. The PWR  116  maintains a count of the hours in which the enclosed fixture is in an active state. Lighting fixture lamps require replacing after a number of hours and failing to do so reduces lighting fixture intensity and may cause a lamp failure with prolonged usage beyond the useful life. A lamp failure can cause damage to the various lighting fixture components. The enclosure  100  provides lamp hour data without requiring access to the lighting fixture  128 . The lamp hour data is also accessible via remote data communication  212  to the user  214 . 
         [0027]    One of ordinary skill in the art will recognize that the enclosure  100  may include components in a different configuration than that depicted in  FIG. 1 . For example, in some embodiments, the FDC  118  may control additional fans which are configured to mix the air inside the enclosure  100 , as opposed to exchanging air with the exterior environment. In another embodiment, components of the system may be located outside of the enclosure  100 . Each of the examples described is exemplary only, and one of ordinary skill in the art will recognize that other configurations are possible without departing from the scope of the present disclosure. 
         [0028]      FIG. 2  is a block diagram illustrating an embodiment of an enclosure and an environmental control system according to various aspects of the present disclosure. The present disclosure is included within an enclosure  200  designed to surround a lighting fixture  226 . The enclosure  200  includes various sensors, the sensors described previously, including a temperature sensor  202 , a relative humidity sensor  204 , an amperage meter  206 , and a voltage meter  208 . 
         [0029]    In one embodiment, the system controller  210  receives the signals from each sensor. The system controller  210  includes the sub-systems as described previously. In addition, the system controller  210  sends and receives information from a remote data communication source  212 . The user  214  can utilize the remote data communication  212  to send and receive data from the system controller  210 , such as power signals, manual override commands, sensor readings, sub-system calculation output, relay status, lighting fixture data, software information, and so on. In one embodiment, the remote data communication protocol is remote device management (RDM), USITT DMX512-A, and/or ArtNet. 
         [0030]    The system controller  210  sends fan duty cycle data to the FDC  216 . The FDC enables at least one fan  222  to exchange air with external ambient air in order to cool the internal air volume temperature. The FDC  216  may also enable at least one mixing fan  224  to stir the air within the enclosure  200  to avoid temperature gradients. In addition, the mixing fan  224  increases effectiveness of the heater(s)  228  and fan(s)  222 . The system controller  210  sends a signal to the power relay  218  to enable power to the lighting fixture  226 . The system controller  210  can interrupt the power relay  218  during a trip condition as a result of overheating within the enclosure  200 . The system controller  210  will not close the power relay  218  until the enclosure temperature drops below a configurable limit for a predetermined time period. In one embodiment, the predetermined time period is four minutes. This time period is determined to be a good compromise between proper cooling time of the enclosure, lighting fixture, and lighting fixture lamp and the minimum amount of time required for certain types of lighting fixture lamps to re-ignite after being deactivated. Certain types of lamps are unable to immediately reactivate because of greatly increased voltage demands of hot lighting fixture lamps. 
         [0031]    The system controller  210  sends heater duty cycle data to the HDC  220 . The HDC enables at least one heater  228  to heat the air within the enclosure  200  in order to maintain the relative humidity of the internal air volume below the minimum value. 
         [0032]      FIG. 3  is a graph that illustrates relative humidity values with respect to internal air temperature values as may be used by various embodiments of the present disclosure. For the sake of clarity, acronyms and definitions for various operational parameters and programmed settings are set forth below. The terms listed and the definitions provided are exemplary only. It will be appreciated that actual parameters and settings utilized during operation of the enclosure  300  can vary within the scope of the claimed subject matter. 
         [0033]    Fan Duty Cycle Controller (FDC)  118 : A system to switch the fan power on periodically according to the required duty cycle relayed by the fan temperature control sub-system. 
         [0034]    Heater Duty Cycle Controller (HDC)  120 : A system to control the duty of the heaters, according to the required duty cycle determined by the heater temperature control sub-system. 
         [0035]    Minimum Temperature Tracking (MTT)  110 : A system to determine the minimum or ideal temperature that will be required to keep the relative humidity of the enclosure internal environment within the requirement of the maximum allowed relative humidity and the minimum enclosure internal temperature. 
         [0036]    Heater Temperature Control sub-system (HTC)  114 : A system to maintain a minimum temperature as determined by the ideal temperature. 
         [0037]    Fan Temperature Control sub-system (FTC)  112 : A system to cool the enclosure proportionately when the enclosed temperature rises above the cooling threshold. 
         [0038]    Load Power (PWR)  116 : Real-time load power calculation. Fan_Duty_Factor: The parameter from which the FDC determines operation duration and frequency of the fan(s). 
         [0039]    Heater_Duty_Factor: The parameter from which the HDC determines operation duration and frequency of the heater(s). 
         [0040]    Max_Humidity  320 : The maximum configurable target of the internal humidity control, independent of internal air temperature. 
         [0041]    Upper_Temp  312 : The maximum target of the internal temperature control, independent of internal air relative humidity. 
         [0042]    Lower_Temp  318 : The minimum configurable target of the internal temperature control, independent of internal relative humidity. 
         [0043]    Minimum_Temp: The calculated minimum target of the internal temperature control required to maintain a relative humidity at or below Max_Humidity. 
         [0044]    Limit_Temp  310 : The temperature at which the trip condition is engaged. Ideal_Temp  316 : The temperature which causes the maximum allowable relative humidity. 
         [0045]    Target_Temp  314 : The temperature between Ideal_Temp  316  and Upper_Temp  312  that the system adjusts to maintain. 
         [0046]    Standard Operating Condition: The state in which the enclosure  100  is powered and turned on. 
         [0047]    Digital Enclosure Control Operating System (DECOS): maintain the environment within an enclosure in an optimal way that meets the elected limits determined by the operational criteria. 
         [0048]    To maintain the temperature in the enclosure  300 , the system utilizes different system duty factor functions to determine temperature targets in real-time. The Limit_Temp  310  is a user-defined temperature enables a trip condition which disables power to the lighting fixture. In one embodiment, the Limit_Temp  310  should be set above normal operating temperatures, but below a temperature where equipment damage could occur. The Upper_Temp  312  is a user-defined temperature that is the maximum target of the internal temperature control. The system will adjust the fan duty cycle to keep the temperature of the volume of air within the enclosure  300  below the Upper_Temp  312 . The fan duty cycle will enable the cooling fans in the temperature range  302  toward the Target_Temp  314 . The Ideal_Temp  316  is the minimum temperature at which the user-defined Max_Humidity  320  target is reached. The system will adjust the heater duty cycle to keep the temperature of the volume of air within the enclosure  300  above the Ideal_Temp  316 . The heater duty cycle will enable the heaters in the temperature range  304  toward the Target_Temp  314 . 
         [0049]    The Target_Temp  314  is a temperature above the Ideal_Temp  316  and below the Upper_Temp  312  at which the system will maintain the temperature of the volume of air within the enclosure  300  according to the duty cycle functions. The Target_Temp  314  is shown as the temperature range  306 . The Target_Temp  314  will adjust to different parameters of the system. In one embodiment, the Target_Temp  314  will adjust toward the Ideal_Temp  316  if the lighting fixture is not powered. This adjustment will lower the duty cycle of the fans and cause the least amount of power draw while emitting the least amount of noise. In another embodiment, the Target_Temp  314  will adjust toward the Upper_Temp  312  when the lighting fixture is powered. This adjustment will lower the duty cycle of the fans and emit the least amount of noise. 
         [0050]    The above sub-systems and parameters are exemplary only. In other contemplated embodiments, more or fewer sub-systems may be utilized in the enclosure environment control system. Moreover, the values and data stored therein may also vary. 
         [0051]    The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the claimed subject matter.