Patent Publication Number: US-2023160774-A1

Title: Display assemblies with differential pressure sensors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 17/872,756 filed Jul. 25, 2022, which claims the benefit of U.S. provisional patent application Ser. No. 63/226,290 filed Jul. 28, 2021, U.S. provisional patent application Ser. No. 63/235,986 filed Aug. 23, 2021, and U.S. provisional patent application Ser. No. 63/240,246 filed Sep. 2, 2021, the disclosures of each of which are hereby incorporated by reference as if fully restated herein. 
    
    
     TECHNICAL FIELD 
     Exemplary embodiments relate generally to display assemblies with differential pressure sensors, including systems and methods for testing and operating the same. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The use of electronic displays, such as for advertising, in the out-of-home market has increased in popularity over recent years. Being located outdoors, such electronic displays are frequently exposed to harsh conditions, including, but not limited to, solar loading, extreme temperatures, precipitation, moisture, contaminants, vandalism, wildlife, and the like. To protect the electronic displays, and associated sensitive components, from such harsh conditions, it is known to place the electronic displays in ruggedized housings. Such housings may fully or partially seal the electronic displays and associated sensitive components. 
     It is known to thermally manage such electronic display assemblies using ambient air and/or circulating gas. Such ambient air may pass through one or more open loop airflow pathways within the assembly, and may thermally interact with circulating gas in one or more closed loop airflow pathways within the assembly where such closed loop pathways are used to remove heat generated by the electronic display assemblies, such as at a backlight. 
     Such electronic display assemblies, particularly those which are fully or partially sealed, are sometimes tested for water ingress before sale or installation. It is known to test such electronic display assemblies by showering them with water for a period of time and checking for water intrusion at the fully or partially sealed areas. However, such water testing does not always provide a strong indication of actual leakage or sealing. For example, internal leak points may not always be exposed to such showering water, or may be so small that water cannot readily pass through the leak points. As another example, water may slide along an area that acts as flashing for a gap which is otherwise gas permeable. Therefore, what is needed is a more reliable form of testing electronic display assemblies for leakage. 
     Systems and methods providing more reliable leak testing for electronic display assemblies (hereinafter also “units”) are provided. In exemplary embodiments, one or more differential pressure sensors may be provided at such units to measure pressure differentials between circulating gas in closed loops or other fully or partially sealed areas (hereinafter also referred to as “testing area(s)”) and ambient air. Certain components of the units may be manipulated to perform such testing and the differential pressure results may be analyzed to determine results. The results may indicate how well sealed the testing area is, the location of leak points, or the occurrence of certain operating conditions, to name a few examples without limitation. 
     For example, without limitation, one or more access panels into one or more testing areas may be closed. This may result in an increase in positive pressure within the associated testing area(s). Because it is generally impossible or impractical to provide a 100% gas impermeable seal between testing areas and the ambient environment, the positive pressure is expected to leak down to equilibrium over time. The time it takes for the testing area to leak down to equilibrium with the ambient air may indicate how well sealed the testing area is. It may be desirable to provide a particular level of seal as indicated by a target minimum leak down time under such conditions. 
     In other exemplary embodiments, the speed of fans in, or in fluid communication with, the testing areas or open loop airflow pathways may be changed to effectuate testing conditions. For example, without limitation, the fans associated with ambient air may be operated at a relatively high output (e.g., operated at 100% speed) while fans associated with the testing area may be operated at a relatively low output (e.g., operated at 0% speed). A change in differential pressure under such conditions may indicate leakage between the testing area and ambient environment. As another example, without limitation, the fans associated with the testing area may be at a relatively high output (e.g., operated at 100% speed) while fans associated with the ambient air and/or open loop(s) may be operated at a relatively low output (e.g., operated at 0% speed). Differential pressure readings may be taken on either side of the fans associated with the testing area. Where the pressure change on one side of such fans is larger (by a positive or negative amount), this may indicate that the leak is on the opposing side of the fan. 
     Differential pressure of operational units may be monitored. The results of such monitoring may be indicative of certain conditions the electronic display assemblies are experiencing. For example, without limitation, where the fans associated with ambient air are operated at a relatively high output (e.g., operated at 100% speed) and the fans associated with the testing area(s) are operated at a relatively low output (e.g., operated at 0% speed), and the pressure difference on one or more sides of the fans associated with the testing area significantly changes and remains changed for more than a certain period of time, this may indicate that an access panel to the testing area is open. If the pressure difference on one or more sides of the fans associated with the testing area significantly changes for a relatively short period of time, that may indicate a mechanical input (e.g., vandalism, shaking, or the like of the electronic display assemblies). If the pressure difference on one or more sides of the fans associated with the testing area significantly changes on a sporadic basis, this may indicate the presence of a wind storm. 
     Where such events are experienced, alerts may be generated based on various thresholds. The alerts may be electronically transmitted over one or more networks to one or more remote electronic devices, such as associated with remote operations centers, owners, operators, or other interested parties. Alternatively, or additionally, the alerts may be displayed on electronic displays of the units themselves. 
     Such testing and monitoring may be performed before a unit is installed. Alternatively, or additionally, such testing and monitoring may be performed for installed units. 
     Any number, type, or kind of such differential pressure sensors may be utilized in such electronic display assemblies in any number of locations within or otherwise at such electronic display assemblies. Furthermore, while differential pressure sensors are discussed, two separate pressure sensors may be utilized (e.g., at least one within or in fluid communication with each testing area) and at least one other one within or in fluid communication with the ambient environment, and the results may be electronically compared to arrive at differential pressure readings. 
     In exemplary embodiments, a first set of one or more fans may be associated with a first electronic display subassembly and a second set of one or more fans may be associated with a second electronic display subassembly. In this manner, at least some circulating gas within a rear chamber may travel in opposite directions. At least some of the circulating gas may recirculate within a given one of the first and second electronic display subassemblies. At least some of the circulating gas may cross over between the first and second electronic display subassemblies. This may create a generally turbulent flow within the rear chamber. Each of the sets of fans may be operated and/or controlled together or separately. 
     Testing procedures may be utilized to identify a location of a leak, such as between the first and second electronic display subassemblies. Initial testing may be performed to establish baseline differential pressures for a display assembly under various operating conditions. Initial testing may be performed by turning off all open loop fans and operating all closed loop fans. If a tested differential pressure is outside a normal range for the display assembly on the low side, a leak may be determined in a lower pressure side of the display assembly (e.g., the negative pressure side). If differential pressure is outside a normal range of a display assembly on the high side, a leak may be determined in a high pressure side of the display assembly (e.g., the positive pressure side). 
     The second set of one or more fans associated with the second electronic display subassembly (sometimes also referred to as the secondary subassembly) may be turned off while the first set of one or more fans associated with the first electronic display subassembly (sometimes also referred to as the primary subassembly) may be turned, or remain, on. If the pressure differential is higher than normal, or within a normal range, no leak may be indicated in the primary side. If the pressure differential is lower than normal, a leak in the primary side may be indicated. 
     The first set of one or more fans may be subsequently turned off while the second set of one or more fans may be turned on. If the pressure differential is higher than normal, or within a normal range, no leak may be noted in the secondary side. If the pressure differential is lower than normal, a leak in the secondary side may be indicated. In this manner, the location of the leak may be further identified. 
     The pressure sensors may be used to identify leaky units. In exemplary embodiments, without limitation, pressure readings may be taken routinely. Where a pressure reading is below, or consistently below, a given threshold, a notification may be generated. The pressure readings may be gauge pressure and/or differential pressure. 
     Further features and advantages of the systems and methods disclosed herein, as well as the structure and operation of various aspects of the present disclosure, are described in detail below with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In addition to the features mentioned above, other aspects of the present invention will be readily apparent from the following descriptions of the drawings and exemplary embodiments, wherein like reference numerals across the several views refer to identical or equivalent features, and wherein: 
         FIG.  1    is a perspective view of an exemplary electronic display assembly in accordance with the present invention also illustrating section line A-A; 
         FIG.  2    is a simplified sectional view of an exemplary embodiment of the electronic display assembly of  FIG.  1    taken along section line A-A; 
         FIG.  3    is a simplified sectional view of another exemplary embodiment of the electronic display assembly of  FIG.  1    taken along section line A-A; 
         FIG.  4    is a simplified sectional view of another exemplary embodiment of the electronic display assembly of  FIG.  1    taken along section line A-A; 
         FIG.  5    is a simplified exemplary electrical schematic for the electronic display assembly of  FIG.  1   ; 
         FIG.  6    is another simplified exemplary electrical schematic for the electronic display assembly of  FIG.  1   ; 
         FIG.  7    is a flow chart with exemplary logic for taking differential pressure readings for use with the electronic display assembly of  FIG.  1   ; 
         FIG.  8 A  is a flow chart with exemplary logic for performing a leak down test of the electronic display assembly of  FIG.  1   ; 
         FIG.  8 B  is a flow chart with other exemplary logic for performing a leak down test of the electronic display assembly of  FIG.  1   ; 
         FIG.  9    is a flow chart with exemplary logic for performing a transference test for the electronic display assembly of  FIG.  1   ; 
         FIG.  10    is a flow chart with exemplary logic for determining various operational conditions of the electronic display assembly of  FIG.  1   ; 
         FIG.  11    is a flow chart with exemplary logic for performing a bias test of the electronic display assembly of  FIG.  1   ; 
         FIG.  12    is a simplified sectional view of another exemplary embodiment of the electronic display assembly of  FIG.  1    taken along section line A-A; 
         FIG.  13 A  is a flow chart with exemplary logic for performing a leak location identification test for the electronic display assembly of  FIG.  1   ; 
         FIG.  13 B  is a continuation of the flow chart of  FIG.  13 B ; 
         FIG.  14    illustrates an exemplary data chart for the electronic display assembly of  FIG.  1    undergoing certain testing; 
         FIG.  15    illustrates another exemplary data chart for the electronic display assembly of  FIG.  1    undergoing certain operations; 
         FIG.  16    illustrates another exemplary data chart for the electronic display assembly of  FIG.  1    undergoing certain operations; 
         FIG.  17    is a flow chart with exemplary logic for performing a dynamic leakdown test of the electronic display assembly of  FIG.  1   ; 
         FIG.  18    is a flow chart with exemplary logic for a low-pressure/leak test of the electronic display assembly of  FIG.  1   ; 
         FIG.  19    is a flow chart with exemplary logic for a low-pressure/leak test of multiple field deployed electronic display assemblies of  FIG.  1   ; and 
         FIG.  20    is a flow chart with other exemplary logic for performing a pressure/leak test of the electronic display assembly of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S) 
     Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details such as detailed configuration and components are merely provided to assist the overall understanding of these embodiments of the present invention. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     Embodiments of the invention are described herein with reference to illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 
       FIG.  1    is a perspective view of an exemplary electronic display assembly (hereinafter also a “unit”)  10  in accordance with the present invention. The unit  10  may include a structural framework  12 . The structural framework  12  may be configured for mounting to a ground surface, such as a sidewalk or street, mounting to a wall or other surface, incorporation into street furniture (e.g., phone booths, bus shelters, benches, railings, combinations thereof, or the like), combinations thereof, or the like. The structural framework  12  may comprise one or more members, panels, cladding, combinations thereof, or the like. 
     The units  10  may comprise one or more electronic display subassemblies  14 . Some or all of the electronic display subassemblies  14  may be attached to the structural framework  12  in a moveable manner, though such is not required. For example, the electronic display subassemblies  14  may be attached to the structural framework in a hinged manner to permit selective movement between a closed position whereby certain parts of the units  10  are fully or partially sealed, and an open position whereby certain parts of the interior of the unit  10  are exposed for access. Fully or partially sealing may be provided in accordance with one or more standards, such as, but not limited to, ingress protection (IP) ratings provided by the International Electrotechnical Commission (e.g., available at https://www.iec.ch/ip-ratings), such as, but not limited to, IP  63 ,  64 ,  65 ,  66 ,  67 , and/or  68  by way of non-limiting example. 
     One or more intakes and exhausts  16  may be provided at the units  10  for ingesting and exhausting ambient air. 
       FIG.  2    through  FIG.  4    illustrate various exemplary embodiments of airflow pathways within the units  10 .  FIG.  2    illustrates an exemplary unit  10   a  with a single electronic display subassembly  14 .  FIGS.  3  and  4    illustrate exemplary units  10   b ,  10   c  with two electronic display subassemblies  14   a ,  14   b  placed in a back-to-back arrangement. Any number of electronic display subassemblies  14  may be utilized in any arrangement with the structural framework  12 . Similar or the same components used in conjunction with units  10  having multiple electronic display subassemblies  14  may use the same numbering with the addition of an “a”, “b”, “c”, and/or “1”, “2”, etc. (e.g.,  14  to  14   a ,  14   b ,  30   a  to  30   a   1 ,  30   a   2 ). 
     Each electronic display subassembly  14  may comprise an illumination device  15 . In exemplary embodiments, the illumination device  15  may comprise a number of lighting elements, such as LEDs, provided at a substrate. In exemplary embodiments, the illumination device  15  may be provided rearward of the electronic display layer  13  to serve as a direct backlight. In other exemplary embodiments, the illumination device  15  may comprise one or more diffusive and/or transmissive layers and the substrate and/or lighting elements may be positioned about the edge of the electronic display layer  13  to provide edge lighting to the same. In certain exemplary embodiments, such as where the electronic display layer  13  is an LED, OLED, or other type of self-illuminating display, the illumination device  15  may not be required. 
     The electronic display layer  13  and/or illumination device  15  may be positioned rearward of a cover  11 . The cover  11  may comprise one or more layers of a transparent or translucent material. In exemplary embodiments, each cover  11  may comprise two layers bonded with an optically clear adhesive. One or more polarizers, anti-reflective materials, combinations thereof, or the like may be disposed on some or all of the cover  11 . The cover  11  may form part of the electronic display subassembly  14  or may be separate therefrom. The cover  11  and the structural framework  12  may together substantially enclose the units  10 , such as with intakes/exhausts  16  exempted. The cover  11  may be configured to move with the electronic display subassembly  14 , may be configured for independent movement, and/or may be fixed to the structural framework  12 . 
     A single or multiple such electronic display subassemblies  14  may be provided at a single unit  10 , such as, but not limited to, in a back-to-back arrangement. The electronic display subassemblies  14  may be of the same or different type and may comprise the same or different components. The electronic display subassemblies  14  may be provided in any arrangement such as portrait or landscape. 
     The intakes and/or exhausts  16  may be fluidly connected to one or more open loop airflow pathways  23  within the units  10 . One or more filters may be provided at the intakes and/or exhausts  16  and/or along the one or more open loop airflow pathways  23  within the units  10 , though such is not necessarily required. 
     A respective one of the open loop airflow pathways  23   a ,  23   b  may extend through a respective one of the electronic display subassemblies  14   a ,  14   b  in exemplary embodiments such that an open loop airflow pathway  34  is provided for each one of the electronic display subassemblies  14 , which may be entirely separate or separated for a distance and rejoined. For example, without limitation, the open loop airflow pathways  23  may extend behind and along at least a portion of the illumination device  15  for the electronic display layer  13  and/or behind and along at least a portion of the electronic display layers  13  itself, such as in the case of LED, OLED, or other self-illuminating displays. However, any type, arrangement, and/or number of airflow pathway(s) may be utilized. The open loop airflow pathways  23  may comprise one or more corrugated layers in exemplary embodiments. 
     One or more closed loop airflow pathways may be provided within the units  10 . In exemplary embodiments, such closed loop airflow pathways may comprise at least a front chamber  26 , which may extend extending between the cover  11  and the electronic display layer  13  as well as a rear chamber  21 , which may extend extending behind the electronic display subassembly  14 , or at least the electronic display layer  13 , but within the structural framework  12 . However, any type, arrangement, and/or number of airflow pathway(s) may be utilized. One or more filters may be provided at or along the one or more closed loop airflow pathways within the units  10 , though such is not necessarily required. Filters, barriers, walls, gaskets, combinations thereof, or the like may provide separation between open and closed loop airflow pathways. 
     Where multiple electronic display subassemblies  14   a ,  14   b  are utilized, the rear chamber  21  may be common to each of the electronic display subassemblies  14   a ,  14   b . A heat exchanger  31  may be located within the rear chamber  21 , though such is not required. The heat exchanger  42  may comprise a multilayer heat exchanger configured to accommodate a common flow  30   c  of the circulating gas through at least some of the layers as well as one or more flows  32   c  of ambient air through at least some other ones of the layers  34   c.    
     An illumination device chamber  27  may extend between each of the electronic display layers  13   a ,  13   b  and the respective illumination devices  15   a ,  15   b . A flow of circulating gas  19   c  within the rear chamber  21  may be separated such that a first portion  19   a  flows through the front chamber  26  and a second portion  19   b  flows through the illumination device chamber  27 . The flows  19   a ,  19   b  may be recombined, such as in the rear chamber  21 . 
     One or more open loop fans  18  may be provided. The same of different open loop fans  18  may be associated with each of the open loop airflow pathways  23 . The open loop fans  18  may be configured to ingest ambient air  17  into the units  10 , exhaust ambient air  17  from the assembly  10 , and/or move ingested ambient air  17  through the one or more open loop airflow pathways  23  when activated. One or more closed loop fans  20  may be provided. The same of different closed loop fans  20  may be associated with each of the closed loop airflow pathways. The closed loop fans  20  may be configured to move circulating gas through said one or more closed loop airflow pathways when activated. The fans  20 ,  18  may be axial fans, centrifugal fans, combinations thereof, or the like. Any number or type of fans  20 ,  18  may be used at any location in the units  10 , and may be provided in banks or sets. The open loop airflow pathways  23  may be separate from the closed loop airflow pathways, though a complete (e.g., gas impermeable) separation is not necessarily required. 
     Examples of such airflow configurations and/or operations may include, for example, without limitation, those shown and/or described in one or more of U.S. Pat. No. 8,854,595 issued Oct. 7, 2014, U.S. Pat. No. 8,767,165 issued Jul. 1, 2014, U.S. Pat. No. 8,654,302 issued Feb. 18, 2014, U.S. Pat. No. 8,351,014 issued Jan. 8, 2013, U.S. Pat. No. 10,660,245 issued May 19, 2020, U.S. Pat. No. 10,194,564 issued Jan. 29, 2019, and/or U.S. Pat. No. 10,398,066 issued Aug. 27, 2019, the disclosures of each of which are hereby incorporated by reference in their entireties. The structure and/or mechanical operation of the units  10 , and the various components thereof, and/or airflow configurations may include those shown and/or described in U.S. Pat. No. 10,485,113 issued Nov. 19, 2019 (the “′113 Patent”), the disclosures of which are hereby incorporated by reference in their entirety. Movement and/or structure for facilitating movement of the electronic display subassemblies  14  may be as shown and/or described in at least the &#39;113 Patent. 
     The unit  10  may comprise one or more controller(s)  22 . The controller(s)  22  may comprise one or more programmable logic devices. The unit  10  may comprise one or more sensors  44 . The sensors  44  may comprise, for example, without limitation, temperature sensors, fan speed sensors, airflow sensors, humidity sensors, relative humidity sensors, air pressure sensors  25 , differential pressure sensors  24 , location sensors, moisture sensors, combinations thereof, or the like. Any type, kind, or number of sensors  44  may be utilized at any number of locations within the units  10 . The sensor(s)  44  may be in electronic communication with the controller(s)  22 . 
       FIG.  5    is a simplified exemplary electrical schematic for the electronic display assembly  10 . A controller  22  may be electrically connected to each of the electronic display subassemblies  14 . The controller  22  may be electrically connected to one or more open loop fans  18  associated with one or more open loop airflow pathways. The open loop fans  18  may be configured to ingest ambient air into the units  10 , exhaust ambient air from the assembly, and/or move ingested ambient air through the one or more open loop airflow pathways when activated. The controller  22  may be electrically connected to one or more closed loop fans  20  associated with the one or more closed loop airflow pathways. The open loop airflow pathways may be separate from the closed loop airflow pathways, though a complete (e.g., gas impermeable) separation is not required. 
     The controller  22  may be electrically connected to one or more differential pressure sensors  24 . Each of the differential pressure sensors  24  may be in fluid communication with at least one of the one or more open loop airflow pathways and/or the ambient environment. The measured pressure of the ambient environment may be referred to as gauge pressure in some cases. Each of the differential pressure sensors  24  may also be in fluid communication with at least one of, or at least one portion of, the one or more closed loop airflow pathways. Each of the differential pressure sensors  24  may be configured to periodically take samples of at least a portion of air pressure of the ambient air and of the circulating gas, such as is shown and/or described with respect to  FIG.  7   , to determine a pressure differential between the measured ambient air and circulating gas. Where more than one closed loop airflow pathway is utilized, a differential pressure sensor  24  may be provided for each closed loop airflow pathway. Alternatively, or additionally, multiple differential pressure sensors  24  may be used in association with each of said one or more closed loop airflow pathways. 
     The differential pressure sensors  24  may include those available from The Sensirion Company of Staefa ZH, Switzerland, such as, but not limited to, the SDP800 series. Available at: https://www.sensirion.com/en/flow-sensors/differential-pressure-sensors/sdp800-proven-and-improved/. However, in exemplary embodiments, the ports for the differential pressure sensors  24  may extend at 90 degrees (e.g., in an elbow arrangement) and may not be a flow-through type which may be susceptible to clogging over time and/or sensitive to tube length. Other exemplary differential pressure sensors  24  may include those available from First Sensor AG of Berlin, Germany (https://www.first-sensor.com/en/) and/or Amphenol of Wallingford, Conn. (https://www.amphenol.com/). These are merely exemplary and are not intended to be limiting. Any type or kind of differential pressure sensor  24  may be utilized. Multiple such differential pressure sensors  24  of the same or different type may be used in a single one of, or in different ones of, the units  10 . 
     In exemplary embodiments, without limitation, the controller  22  may comprise an EPROM board, which may be regularly replaced with maintenance of the units  10 . In exemplary embodiments, without limitation, at least a portion of the differential pressure sensors  24  may be provided at, or be integrated with, the controller  22 . A first set of tubes or other fluid passageways may fluidly connect a first portion of each of the differential pressure sensors  24  to a respective one of the testing areas. A second set of tubes or other fluid passageways may fluidly connect a second portion of each of the differential pressure sensors  24  to one of the open loop airflow pathways and/or the ambient environment. In exemplary embodiments, without limitation, the second set of tubes or other fluid passageways, and/or the differential pressure sensor  24  itself, may be connected to, or provided on, a bottom portion or surface of the unit  10  so as to avoid water or other precipitation. Any number of tubes of any size, shape, length, or type may be provided to place the differential pressure sensors  24  in fluid communication with any number of areas inside or outside of the units  10 . In this manner, multiple areas may be tested at the same or different times. Furthermore, this may permit placement of the differential pressure sensors  24  in a convenient location, such as, but not limited to, in the rear chamber  21  and/or part of a larger electronic board to keep it cooled, powered, and/or protected. 
     Data from the differential pressure sensors  24  may be sent to the controller  22 . The controller  22  may be configured to command the differential pressure sensors  24  to take readings periodically, continuously, sporadically, at intervals, on-demand, combinations thereof, or the like. Alternatively, or additionally, the differential pressure sensors  24  may be configured to take such measurements periodically, continuously, sporadically, at intervals, on-demand, combinations thereof, or the like automatically. 
     The controller  22  may be electrically connected to a network communication device  29 . The network communication device  29  may be configured to receive data from the controller  22  for transmission over one or more networks  28  to one or more electronic devices  30 . The network  28  may comprise cellular networks, wireless networks, wired networks, combinations thereof, or the like. The electronic devices  30  may comprise personal computers, smartphones, tablets, network operation centers, combinations thereof, or the like. Multiple such differential pressure sensors  24  may be utilized and the results may be averaged or otherwise combined or compared. 
       FIG.  6    is another simplified exemplary electrical schematic for the unit. Two separate pressure sensors  25   a ,  25   b , may be utilized, one in association with the circulating gas and one in association with the ambient air, and their data sent to the controller  22  to create a differential pressure reading. A number of such sets of pressure sensors  25   a ,  25   b  may be utilized, one of which may be positioned to take a pressure reading of circulating gas, and one of which may be positioned to take a pressure reading of ambient air. Multiple such sensors  25   a ,  25   b  may be utilized and the results may be averaged or otherwise combined or compared. 
       FIG.  7    illustrates logic which may be undertaken by the differential pressure sensors  24  and/or the controller  22  to create a differential pressure reading. The differential pressure sensors  24  may be configured to take pressure readings of the circulating gas and the ambient air at the same or different times. Regardless, corresponding measurements of the circulating gas and the ambient air may be compared, such as by subtraction for example, without limitation, to arrive at a differential pressure reading. In the case of pressure sensors  25 , the controller  22  may determine the differential pressure based on readings from each of the sensors  25   a ,  25   b . In the case of differential pressure sensors  24 , the differential pressure sensors  24  and/or the controller  22  may be configured to determine the differential pressure readings. 
     In exemplary embodiments, the testing area may include the front chamber  26  and the illumination device chamber  27  such that a differential pressure may be taken between the front chamber  26  and the illumination device chamber  27 . Such differential pressure readings may be determined by way of one or more differential pressure sensors  24  and/or multiple sensors  25 . This may be used to, for example, without limitation, validate computer models regarding differential pressures between the front chamber  26  and the illumination device chamber  27 , field testing, during operation, combinations hereof, or the like. Maintaining this differential pressure may be important for maintaining the position of the electronic display layer  13 , such as to prevent or reduce bowing of the same. 
       FIG.  8 A  and  FIG.  8 B  are flow charts with exemplary logic for performing leak down testing of the electronic display assembly  10 . The fans  18 ,  20  may be deactivated (e.g., operated at 0% speed) and/or operated at minimal levels (e.g., less than 5%, between 0-10%). Such conditions may be commanded by the controller  22 . A first differential pressure reading may be taken by the differential pressure sensors  24  and/or pressure sensors  25 . 
     As shown with particular regard to  FIG.  8 A , an access panel to a fully or partially sealed portion of a closed loop airflow pathway with the unit  10  being tested (i.e., the testing area) may be moved from an opened position to a closed position to fully or partially seal the closed loop airflow pathway. Closing the access panel may create a positive or increased pressure within the testing area relative to ambient air, such as, but not limited to, in the range of 100-200 Pa. A timer may be started while, just before, or just after, the access panel is closed. 
     As shown with particular regard to  FIG.  8 B , pressure changes may be otherwise induced at the unit  10  being tested. In exemplary embodiments, a positive or negative pressure may be induced. Such pressure changes may be induced by fluidly connecting, and operating, one or more pressure inducing devices, such as, but not limited to, pumps, vacuums, valves, combinations thereof, or the like, to the closed loop airflow pathways of the unit  10 . Alternatively, or additionally, the one or more pressure inducing devices may be fluidly connected to the open loop airflow pathways, which may be temporarily sealed to induce the pressure change. In exemplary embodiments, without limitation, a negative pressure may be induced by providing a vacuum by way of the one or more pressure inducing devices. Examples of the pressure inducing devices include, but are not limited to, the F600 leak tester from ATEQ of Les Clayes-sous-Bois, France (https://www.ateq-leaktesting.com/products/leak-tester/f600/). The pressure change may be induced and controlled until a steady state desired pressure differential is created, which may comprise a target number (with or without a margin) or range. Steady state may include equilibrium and/or within a margin thereof. 
     Inducing pressure differentials by closing the access panel of the unit  10 , such as shown and/or described with respect to  FIG.  8 A  may be particularly useful for field testing of already installed units. For example, this may permit testing without the need to bring, attach, operate, etc. a pressure inducing device. Inducing pressure differentials by a pressure inducing device, such as shown and/or described with respect to  FIG.  8 B , may be particularly useful for pre-installation testing of a manufactured unit. For example, this may provide more consistent and accurate testing. However, either procedure may be used with installed or uninstalled units  10  and/or in combination with each other. 
     Regardless, differential pressure readings may be taken, continuously, periodically, at intervals, sporadically, combinations thereof, or the like, until an equilibrium, or within a predetermined range of an equilibrium (e.g., within 10 Pa), between the testing area and ambient pressure is reached. When such equilibrium, or within the predetermined range of an equilibrium, is reached, the timer may be stopped. 
     As shown with particular regard to  FIG.  8 B , alternatively or additionally, the differential pressure readings may be taken across a range and/or until a target is reached. For example, without limitation, the range may be from an induced pressure spike of 175-290 Pa, or a target within or about such a range, such as, but not limited to, 175, 250 or 290 Pa, and may be monitored until reaching 175-125 Pa, or a target within or about such a range. Any range, ranges, and/or thresholds may be used for the induced pressure spike and/or the leakdown target. Such ranges and/or thresholds may be relative to the peak pressure induced and/or the leakdown target. Pre-installation testing may be performed along these lines to establish benchmark leak down times. Such benchmark data may be used and compared with field tests, for example, to establish pass/fail criteria. This may be particularly helpful because field testing by closing an access panel, such as shown and/or described with respect to  FIG.  8 A , may result in varying pressure spikes. The pass/fail criteria may be adjusted based on the pressure spike induced based on existing data or extrapolated from existing data. 
     Regardless, such sampling may be commanded by the controller  22 . The controller  22  may comprise a timer or other timekeeping device for measuring the time. The time may be reported by itself as an indication of how well sealed the testing area is as a longer time may indicate a more fully sealed unit  10 . Alternatively, or additionally, where the time fails to meet or exceed a predetermined threshold (e.g., 10 minutes), an alert regarding leakage may be generated. Alternatively, or additionally, where the time meets or exceeds the predetermined threshold, an indication that the unit  10  passes testing may be generated. Any amount of time may be used for the threshold, but may generally be on the order of several minutes. Multiple such thresholds may be provided to indicate various levels of sealed (e.g., well-sealed, mostly sealed, poorly sealed). 
     The alerts, reports, indications, notifications, combinations thereof, or the like shown and/or described herein, may be generated at the controller  22  and reported to the one or more electronic devices  30  by way of the one or more networks  28 . For example, without limitation, such alerts, reports, indications, notifications, combinations thereof, or the like may be accessible through a web-based interface, application, combinations thereof, or the like. Alternatively, or additionally, the controller  22  may be configured to display such alerts, reports, indications, notifications, combinations thereof, or the like at one or more of the electronic display subassemblies  14 . For example, without limitation, the controller  22  may command the electronic display subassemblies  14  to display a message such as “Hey service tech, I&#39;m leaking”, for example, without limitation, or similar variations thereof may upon determination that the amount of time of a leak down test performed fails to meet or exceed the predetermined threshold. 
     Such leak down testing may be performed for a number of testing areas within each unit  10 . In exemplary embodiments, leak down testing may be performed periodically, on demand, sporadically, and/or every time one of the access panels is opened, such as determined by one or more sensors associated with each such access panel and connected to said controller  22 . Instructions to perform such leak down testing may be received at the controller  22  from the one or more electronic devices  30 . 
     In exemplary embodiments, without limitation, the access panel may be a front assembly comprising one of the electronic display subassemblies  14  which forms a door. Such exemplary embodiments may be shown and/or described in at least the &#39;113 Patent, for example, without limitation. 
     Alternatively, or additionally, a rate of change in differential pressure may be calculated by the controller  22  and used as a measure of leakage severity. Alerts regarding the same may be so generated based on various thresholds. 
       FIG.  9    is a flow chart with exemplary logic for performing a transference test for the electronic display assembly  10 . Optionally, a baseline or steady-state differential pressure reading may be taken based on normal operations of the unit  10 . The closed loop fans  20  may be deactivated (e.g., operated at 0% speed, operated at less than 1% speed) and/or operated at minimal levels (e.g., less than 5%, less than 10%). The open loop fans  18  may be operated at maximum (e.g., operated at 100% speed) and/or high levels (e.g., above 95%, above 90%). Optionally, some or all heat generating equipment of the unit  10 , such as, but not limited to, the electronic display subassembly  14  or components thereof (e.g., any backlight or other illumination elements), may be deactivated to prevent heat buildup while the closed loop fans  20  are deactivated or operated at minimal levels. Such conditions may be created by commands from the controller  22  in exemplary embodiments. A differential pressure reading may be taken. If the differential pressure reading falls outside a target (e.g., baseline or steady state) by a predetermined threshold, such as, but not limited to, 10 Pa, an alert may be generated. Commands for such measurements may be made by way of the controller  22 . If the differential pressure reading meets or falls below the predetermined threshold, an indication of passing the test may be generated. This procedure may test for transference of pressure between the testing area(s) and the open loop airflow pathways and/or ambient environment, thereby indicating leaking between the same. Transference above a predetermined threshold may trigger an alert, such as determined and/or generated by the controller  22 . The threshold may be any amount but may be on the order of 10&#39;s or 100&#39;s of pascals in exemplary embodiments. 
       FIG.  10    is a flow chart with exemplary logic for performing operational tests of the electronic display assembly  10 . The same or similar procedures as shown and/or described with regard to  FIG.  9    may be followed. Where the differential pressure readings meet or exceed a predetermined threshold, which may be the same as or different from the threshold(s) used for the transference test, and continues for a predetermined period of time (e.g., several seconds or minutes), such as determined by the controller  22  for example, without limitation, an alert may be generated that an access panel associated with the testing area is open. Opening the access panel may create a pressure change outside of normal parameters because the testing area is no longer well sealed. Where the differential pressure readings meet or exceed the same or different predetermined threshold for a relatively short period of time (e.g., less than several seconds, or less than 1 second), such as determined by the controller  22  for example, without limitation, an alert may be generated indicating that mechanical input is likely occurring (e.g., vandalism, shaking, or the like). Mechanical input may temporarily shrink or expand the available volume of the testing area, thereby temporarily increasing or decreasing pressure relative to ambient air. Where the differential pressure readings meet or exceed the same or different predetermined threshold sporadically, such as determined by the controller  22  for example, without limitation, this may indicate the presence of a windstorm, which may bring associated rapid changes to ambient pressures. Alerts or other notifications regarding such determinations may be provided, such by way of the controller  22 , for example, without limitation. Differential pressures may be monitored on demand and/or on an ongoing basis to make such determinations. The thresholds may be any amount but may be on the order of 10&#39;s or 100&#39;s of pascals in exemplary embodiments, without limitation. 
       FIG.  11    is a flow chart with exemplary logic for performing a bias test of the electronic display assembly  10 . Optionally, a baseline or steady-state differential pressure reading may be taken based on normal operations of the unit  10 . A differential pressure reading may be taken at multiple locations, such as on either side of one or more of the closed loop fans  20 . One side of each closed loop fan  20  may be configured to create a pressure drop to create airflow by design. As such, each closed loop fan  20  may have a first side or portion associated with a positive pressure, and a second side or portion associated with a negative pressure. Alternatively, or additionally, a single differential pressure reading may be taken on either side of the one or more closed loop fans  20 . For example, without limitation, the differential pressure sensor(s)  24  may be in fluid communication with portions of the testing area on either side of the closed loop fans  20 . As another example, without limitation, the pressure sensors  25   a ,  25   b  may be placed on either side of the closed loop fans  20 . 
     The open loop fans  18  may be deactivated (e.g., operated at 0% speed, less than 1% speed) and/or operated at minimal levels (e.g., less than 5%, less than 10%). The closed loop fans  20  may be operated at maximum (e.g., operated at 100% speed) and/or high levels (e.g., above 95%, above 90% speed). This may create a pressure drop across the closed loop fans  20  (e.g., positive pressure on one side, negative on the other). Optionally, some or all heat generating equipment of the unit  10 , such as, but not limited to, the electronic display subassembly  14  or components thereof (e.g., any backlight or other illumination elements), may be deactivated to prevent heat buildup while the closed loop fans  20  are deactivated or operated at minimal levels. Such conditions may be created by commands from the controller  22 , for example, without limitation. A pressure or differential pressure reading may be taken at multiple locations, such as on either side of one or more of the closed loop fans  20 . 
     Where the pressure or differential pressure readings indicate a bias towards the positive pressure side of the closed loop fans  20 , this may indicate a leak in the negative pressure side of the closed loop fans  20 . Where the pressure or differential pressure readings indicate a bias towards the negative pressure side of the closed loop fans  20 , this may indicate a leak in the positive pressure side of the closed loop fans. For example, without limitation, where the pressure or differential pressure on the positive pressure side of the closed loop fans  20  increases by 300 Pa and the pressure or differential pressure of the negative pressure side of the closed loop fans  20  decreases by 100 Pa, bias towards the positive pressure side of the closed loop fans  20  may be established indicating a leak of the negative pressure side of the closed loop fans  20  due to the relatively well sealed positive pressure side and the relatively not well sealed negative pressure side of the testing area. As another example, without limitation, where the pressure or differential pressure on the negative pressure side of the closed loop fans  20  decreases by 300 Pa and the pressure or differential pressure of the negative pressure side of the closed loop fans  20  increases by 100 Pa, bias towards the negative pressure side of the closed loop fans  20  may be established indicating a leak of the positive pressure side of the closed loop fans  20  due to the relatively well sealed negative pressure side and the relatively not well sealed positive pressure side of the testing area. 
     While differential pressure readings are discussed in several places, non-differential pressure readings may alternatively or additionally be utilized, such as by pressure sensors  25  in lieu of, or in addition to, differential pressure sensors  24 . Differential pressure readings and sensors may be used as they may be more representative of pressure changes resulting from leakage. For example, ambient pressure may vary significantly during normal operations due to ambient pressure changes resulting from fronts, winds, and/or other weather events as well as fluctuations caused by operation of the open loop fans  18 . Pressure of circulating gas may also change with such weather events and/or operation of the closed loop fans  20 . Because it may be impossible, difficult, or impractical to prove an entirely gas impermeable seal between the closed loop portions and ambient or open loop portions of the unit  10 , such pressure changes may result in pressure variations throughout some or all of the unit  10 . Thus, a change in differential pressure may be a more accurate representation of leakage or changes in the amount of seal in the testing area and/or any changes thereto. 
     The testing shown and/or described herein may be performed periodically, continuously, on demand, sporadically, combinations thereof, or the like. In exemplary embodiments, without limitation, such testing may be performed whenever appropriate conditions occur naturally or by chance. Alternatively, or additionally, such conditions and associated testing may be commanded. The conditions for testing, measurements, analysis, reports, combinations thereof, or the like, may be performed at or by the controller  22  in exemplary embodiments. 
     The testing shown and/or described herein may be performed at units  10  awaiting installation or already installed and operating in the field. In exemplary embodiments, without limitation, the baseline or steady-state differential pressure reading may be based on testing performed before or when the unit  10  was installed, and may be used for comparison against operational condition for the same or different units  10 . The electrical connections shown and/or described herein may be direct or indirect. The closed loop airflow pathways (e.g., the testing areas) shown and/or described herein may be loops or enclosed areas where the circulating gas travels in a loop therein. The closed loop airflow pathways/testing areas may be any size or shape. Alternatively, or additionally, thresholds, baselines, or other readings may be determined by averages or other collective measures of the same or different units  10 . 
     The use of differential pressure sensors  24  and/or pressure sensors  25  in testing or field use, such as an alternative to water shower testing, moisture sensing, combinations thereof, or the like, may provide more accurate and/or precise results. Such pressure sensing may be able to detect intrusion points not otherwise found in water shower testing, moisture sensing, combinations thereof, or the like. Alternatively, or additionally, such pressure sensing may provide a better indication of the location of the intrusion points, such as, but not limited to, on which side of one of the closed loop fans  20 , which part of the closed loop airflow pathway, and/or which area of the unit  10  the intrusion point is located. 
     In exemplary embodiments, without limitation, pressures may be generated within the units  10  by way of one or more pumps or other mechanical devices. The pumps may be fluidly connected to portions of the units  10 , such as, but not limited to, the closed loop airflow pathways, to generate pressures, such as positive pressures within the units  10 . These pressures may be generated to perform various testing, such as, but not limited to, leak down testing in a manufacturing facility and/or in the field to name some non-limiting examples. This may advantageously permit testing in various circumstances and/or consistent and reliable testing measures. 
       FIG.  12    is another exemplary embodiment of airflow pathways within the units  10   d . Some or all of the same or similar components used in the units  10 - 10   c  may be utilized in the unit  10   d . Similar or the same components used in conjunction with the unit  10   d , which may comprise multiple electronic display subassemblies  14 , may use the same numbering with the addition of an “a”, “b”, “c”, etc., and/or “1”, “2”, etc. (e.g.,  14  to  14   a ,  14   b ,  30   a  to  30   a   1 ,  30   a   2 ). Each electronic display subassembly  14  may comprise a set or bank of one or more closed loop fans  20 . For example, a first electronic display subassembly  14   a  (sometimes also referred to as the primary subassembly) may comprise a first set of one or more closed loop fans  20   a . The same, or substantially the same, subassemblies  14  may be used for each side of the unit  10   d . Each of the sets of closed loop fans  20  may be operated and/or controlled together or separately. 
     The first set of one or more closed loop fans  20   a  may be mounted to the first electronic display subassembly  14   a . The first set of one or more closed loop fans  20   a  may comprise one or more centrifugal type fans mounted within or to a housing attached to a rear surface of the housing for the open loop airflow pathway  23   a , though such is not necessarily required. In exemplary embodiments, without limitation, the first set of one or more closed loop fans  20   a  may be positioned adjacent to an entrance to the front chamber  26   a  and/or the illumination device chamber  27   a  of the first electronic display subassembly  14   a , and may be configured to push circulating gas therethrough, such as to create the first and second portions  19   a   1 ,  19   a   2  of the flow of circulating gas, when activated. This may result in positive, or relatively high, pressures within one or more of the front chambers  26   a  and/or the illumination device chamber  27   a.    
     The second set of one or more closed loop fans  20   b  may be mounted to the second electronic display subassembly  14   b . The second set of one or more closed loop fans  20   b  may comprise one or more centrifugal type fans mounted within or to a housing attached to a rear surface of the housing for the open loop airflow pathway  23   b , though such is not necessarily required. The second set of one or more closed loop fans  20   b  may be positioned adjacent to an entrance to the front chamber  26   b  and/or the illumination device chamber  27   b  and may be configured to push circulating gas therethrough, such as to create the first and second portions  19   b   1 ,  19   b   2  of the flow of circulating gas, when activated. This may result in positive, or relatively high, pressures within one or more of the front chambers  26   b  and/or the illumination device chamber  27   b.    
     In this manner, at least some circulating gas  19   c  within a rear chamber  21  may travel in opposing directions. For example, without limitation, a first flow  19   c   1  of circulating gas exiting the front chamber  26   a  and/or illumination device chamber  27   a  of the first electronic display subassembly  14   a  may substantially flow in one direction, while a second flow  19   c   2  of circulating gas exiting the front chamber  26   b  and/or illumination device chamber  27   b  of the first electronic display subassembly  14   b  may substantially flow in an opposing direction. At least some of the circulating gas  19   c  may recirculate within a given one of the first and second electronic display subassemblies  14 , and at least some of the circulating gas  19   c  may cross over between the first and second electronic display subassemblies  14 . This may create a generally turbulent flow within the rear chamber  21 . 
     While sometimes discussed as a first and second electronic display subassembly  14   a ,  14   b , the unit  10   d  may comprise any number of electronic display subassemblies  14 , each of which may comprise a set or bank of one or more fans  20 . The rear passageway  21  may be common to at least two, or all of, the electronic display subassemblies  14 . The electronic display subassemblies  14  may be provided within a common housing and/or mounted to a common structural framework  12  in exemplary embodiments. 
       FIG.  13 A  through  FIG.  13 B  illustrate testing procedures that may be utilized to identify a location of a leak between the various electronic display subassemblies  14 . While sometimes discussed with regard to a first and second electronic display subassembly  14   a ,  14   b , the procedure may be used with regard to any number of electronic display subassemblies  14  of a given unit  10   d.    
     Differential pressure readings of the unit  10   d , or a unit  10  of the same or substantially similar design, may be taken to establish a baseline, normal reading or range for such units  10   d , such as while operating under various conditions (temperature, fan speed, etc.). Differential pressure readings may be subsequently taken, such as, but not limited to, as part of pre-installation testing, field testing, combinations thereof, or the like. 
     The open loop fans  18  may be turned off, or be left off. The closed loop fans  20  may be turned on, or left on. For example, the closed loop fans  20  may be operated at maximum (e.g., 100%) or relatively high (e.g., above 95%, above 90%) speed, and the open loop fans  18  may be operated at 0% or minimum (e.g., less than 5%) speed. If differential pressures are within a normal range for the display assembly  10   d , then no leak may be indicated. If tested differential pressure is outside a normal range for the display assembly  10   d  on the low side, a leak may be determined in a lower pressure side for the display assembly  10   d  (e.g., the negative pressure side). This may be the intake side of the closed loop fan units  20 . If tested differential pressure is outside a normal range for the display assembly  10   d  on the high side, a leak may be determined in a high pressure side of the display assembly  10   b  (e.g., the positive pressure side). This may be the exhaust side of the closed loop fan units  20 . 
     The second set of one or more fans  20   b  associated with the second electronic display subassembly  14   b  (sometimes also referred to as the secondary subassembly) may remain, or be turned, off (e.g., operated at 0% speed), while the first set of one or more fans  20   a  associated with the first electronic display subassembly  14   a  (sometimes also referred to as the primary subassembly) may remain, or be turned, on (e.g., operated at 100% speed). If the pressure differential is higher than normal, or within a normal range, no leak may be noted in the primary side  14   a . If the pressure differential is lower than normal, a leak in the primary side  14   a  may be indicated. 
     The first set of one or more fans  20   a  associated with the first electronic display subassembly  14   a  may subsequently be turned, or remain, off (e.g., operated at 0% speed) while the second set of one or more fans  20   b  associated with the second electronic display subassembly  14   b  may remain, or be turned, on (e.g., operated at 100% speed). If the pressure differential is higher than normal, or within a normal range, no leak may be noted in the secondary side  14   b . If the pressure differential is lower than normal, a leak in the secondary side  14   b  may be indicated. 
     This procedure may permit presence and location of any leaks to be further identified. This procedure may be repeated any number of times for any number of subassemblies  14 . The procedure may be performed in any order. For example, the secondary side  14   b  may be tested before the primary side  14   a , or vice versa. Certain steps may be repeated, omitted, or performed out of order. 
     The leak location or other indications may be made at the unit  10   d , such as by display at one or more of the electronic display layers  13 , or reported to one or more remote electronic devices  30 , such as by way of the network  28  and/or the network communication devices  29 . While differential pressures are sometimes discussed, absolute pressures may alternatively or additionally be utilized. Various fan speeds may be used for testing. For example, without limitation, while 100% fan speed may be utilized in some cases, a relatively high speed may alternatively be utilized (e.g., &gt;89%). As another example, without limitation, while 0% fan speed may be utilized in some cases, a relatively low speed may alternatively be utilized (e.g., &lt;10%). 
       FIG.  14    illustrates an exemplary data chart  60  for a unit  10  undergoing certain testing. The data chart  60  is a non-limiting example of the type or kind of chart that may be generated by the controller(s)  22 , such as for display at the electronic device(s)  30 . The sensors  44  may be sufficient to generate the data chart  60 . The data chart  60  may reflect some or all of the steps shown and/or described with respect to any of  FIGS.  7 - 11  and/or  13 A- 13 B . In exemplary embodiments, without limitation, the data chart  60  may reflect a static leakdown test performed on a unit  10  in a controlled environment, such as pre-installation testing. The testing procedure may generally reflect the steps of  FIGS.  8 A- 8 B , without limitation. 
     As generally noted at item  62 , leakdown time may be determined. As indicated generally at item  64 , differential pressure changes due to changing fan  18  and/or  20  speed or other conditions may be recorded as temperature fluctuates, which affects pressure. As generally provided in the data chart  60 , fan speed, especially of the open loop fans  18 , may be highly correlated with differential pressure readings. 
       FIG.  15    illustrates an exemplary data chart  60 ′ for a unit  10  undergoing certain operations. The data chart  60 ′ is a non-limiting example of the type or kind of chart that may be generated by the controller(s)  22 , such as for display at the electronic device(s)  30 . The sensors  44  may be sufficient to generate the data chart  60 ′. In exemplary embodiments, without limitation, the data chart  60 ′ may reflect a dynamic leakdown test performed on an operational unit  10 . As generally indicated at item  65 , a variety of differential pressures readings may be provided during normal daytime operations, such as in reflect of varying solar loads, backlight adjustment, weather conditions, combinations thereof, or the like. During nighttime hours, as generally indicated at item  66 , when solar loading is minimal to non-existent, and in some cases, backlights may be turned off or dimmed significantly, differential pressure readings may be more consistent. The data chart  60 ′ may represent a relatively well-sealed unit  10  not experiencing significant leaking. No alerts may be generated due to the type or kind of data received as illustrated in the data chart  60 ′. 
       FIG.  16    illustrates an exemplary data chart  60 ″ for a unit  10  undergoing certain operations. The data chart  60 ″ is a non-limiting example of the type or kind of chart that may be generated by the controller(s)  22 , such as for display at the electronic device(s)  30 . The sensors  44  may be sufficient to generate the data chart  60 ″. In exemplary embodiments, without limitation, the data chart  60 ″ may reflect a dynamic leakdown test performed on an operational unit  10 . As generally indicated at item  68 , a fairly consistent differential pressures readings provided during normal daytime operations and/or nighttime operations. As the unit  10  might be expected to experience varying differential pressure readings during normal operations, the data chart  60 ″ may reflect a less well-sealed unit and/or a leaking unit of concern. One or more alerts may be generated in response to the type or kind of data received as illustrated in the data chart  60 ″. 
       FIG.  17    provides exemplary static leakdown testing procedures. The unit  10  may be operated normally. Alternatively, or additionally, normal operations may be artificially mimicked, such as in a shortened timeframe to simulate normal conditions. In this fashion, dynamic leakdown testing may be performed in fielded units or in controlled environments (e.g., pre-installation testing). Such normal, or simulated normal, operating conditions may include, for example, without limitation, simulated solar loading (e.g., by provided by one or more artificial light sources), changing fan  18  and/or  20  speed, adjusting backlight power levels, changing ambient air temperatures (e.g., using heaters, air conditioners, psychrometric testing chambers, etc.), combinations thereof, or the like. Where differential pressure readings change as expected, a determination may be made that no significant leaks are likely present. Where differential pressure readings do not change as expected, a determination may be made that one or more significant leaks are likely present. 
     One example of a simulated day may include, without limitation, operating the unit  10  for an hour with full daytime brightness and a white screen, and 100% closed loop fan  20  and open loop fan  18  fan speed, and transitioning to the short night, by dropping to nighttime brightness (−300 nits) and operating the fans  18  and  20  in a night mode (open loop fans  18  fans allowed to go to zero and only ramp up as required, and the closed loop fans  20  allowed to go as low as 30% and ramp up from there as required). This is merely exemplary and not intended to be limiting. For example, without limitation, any time periods, backlight levels, fan  18  and/or  20  speeds, cycles, combinations thereof, or the like, may be utilized. A relatively long static leakdown time may correlated with a relatively long dynamic leakdown testing time, and a relatively short static leakdown time may correlate with a relatively short dynamic leakdown time. The difference in static and dynamic leakdown times may be multiple orders of magnitude (e.g., 10 minute static leakdown correlating to an hour of dynamic leakdown). A longer static and/or dynamic leakdown time may be associated with a better sealed unit  10 . 
     Changes in differential pressure readings may be expected with changes in temperature. Changes in temperature may be expected when fans  18  and/or  20  are activated, deactivated, or changed in operational speed. Changes in temperature may, alternatively or additionally, be expected when power to the backlight is increased or decreased. Changes in temperature may, alternatively or additionally, be expected during different hours of the day and/or times of year, such as due to varying solar loading, weather conditions, night time conditions, day time conditions, combinations thereof, or the like. In this manner, changes in differential pressure readings may be expected with changes in any one or more of: temperature (ambient or otherwise), ambient lighting, fan  18  and/or  20  speed, time of day, time of year, weather conditions, backlight power, operational power draw, combinations thereof, or the like. Such changes in conditions may occur naturally, such as in fielded, operational units, or may be induced, such as by the controller(s)  22  and/or remote electronic device(s)  30  for testing. 
     The controller(s)  22  and/or remote device(s)  30  may be configured to automatically and/or electronically determine if sufficiently correlated changes in differential pressure are experienced, such as by way of review of the data charts  60 ,  60 ′, or  60 ′″. Where sufficiently correlated changes in differential pressure are experienced, no alert and/or an indication of no significant leak detected may be provided. Where sufficiently correlated changes in differential pressure are not experienced, an alert and/or an indication of the likely presence of a significant leak may be provided. Comparisons may be made in discrete instances, such as against objective criteria, and/or against a baseline established from review of historical information, by way of non-limiting example. 
       FIG.  18    through  FIG.  20    illustrates exemplary operations of automated low-pressure/leak detection and/or alerting features for the units  10  and/or related systems. Related systems may include multiple units  10  reporting to a common remote electronic device, network operations center, or the like. The terms low-pressure and/or leak detection may be used interchangeably in at least some instances herein as relatively low pressure may be indicative of a leak, particularly when such lower pressure is continually indicated overtime and/or where pressure increases would normally be expected. 
     The controller(s)  22  of the units  10  or related systems may be configured to periodically, randomly, continuously, some combination thereof, or the like, take pressure readings for the units  10 , such as by way of the differential pressure sensor(s)  24  and/or pressure sensors  25 . In exemplary embodiments, without limitation, each unit  10  may be polled for a pressure reading at least daily, though polling may take place multiple times in a day or other twenty-four-hour period. The units  10  may be polled based on locally issued and/or remotely issued commands and/or locally stored and/or remotely stored programming instructions. 
     Where the pressure readings are below a given threshold, either in a single instance and/or over multiple instances within a given time period, the controller(s)  22  may be configured to automatically generate and/or transmit an alert, such as to one of more remote electronic device(s)  30  by way of the network(s)  28  and/or network communication device(s)  29 . The alert may indicate the low pressure and/or a likely leak. Multiple ones of the units  10  may be connected to the one of more remote electronic device(s)  30  and/or network(s)  28 , such as by way of the network communication device(s)  29  at each such unit  10 . In this way, a singular unit  10  may be monitored or a whole network of field installed operating units  10 , by way of non-limiting example. 
     The given threshold may be an absolute pressure value and/or differential pressure value. The given threshold may be approximately ambient pressure, atmospheric pressure, and/or a margin above in terms of absolute pressure, such as but not limited to, somewhere between 1-2 atmospheres, though any threshold may be utilized. When utilizing differential pressure, the given threshold may be relatively smaller, such as somewhere between 0-15 psi, though any threshold may be utilized. The threshold may be a floor, through a range, or the like may alternatively or additionally be utilized. The alert may be generated following a single reading, or multiple readings over time. 
     Alternatively, or additionally, an alert may be generated where the unit(s)  10  are operated normally but the pressure readings do not change significantly over time. Normal operations may include dynamic fan operations, natural ambient pressure changes, natural ambient temperature changes, dynamic backlight operations, combinations thereof, or the like. Some or all of these, or other factors, may affect internal pressures, such as due to known pressure and temperature relationships, induced fan pressures, combinations thereof, or the like. Where the absolute or differential pressure changes with such normal operations, the unit  10  may be determined to be operating normally. Where the absolute or differential pressure fails to change significantly during such normal operations, such as more than a predetermined amount, range, fit within minimums and/or maximums, combinations thereof, or the like, an alert may be automatically generated and/or transmitted. Such alerts may be generated based on singular reading or multiple readings overtime. For example, without limitation, a low pressure and/or leaking unit  10  may be determined where a time plotted graph of pressure readings remains relatively flat. 
     Time between taking readings may be on the order of seconds, fractions of a second, minutes, hours, days, combinations thereof, or the like. For example, without limitation, at least two readings may be taken at least 5 minutes apart, however any number of readings with any intervening period of time may be utilized. 
     Alternatively, or additionally, an alert may be generated where the unit(s)  10  are intentionally operated in a manner anticipated to cause pressure changes, but fails to do so. 
     Additional testing, such as but not limited to, a static and/or dynamic leakdown test may be automatically initiated to confirm the findings of low pressure/likely leaking. The static and/or dynamic leakdown testing may be as shown and/or described herein. 
     Alternatively, or additionally, operations may be induced which are anticipated to cause pressure changes, including increasing or decreasing open loop and/or closed loop fan  18 ,  20  speed, increasing backlight luminance, combinations thereof, or the like to confirm the presence of a likely leak. In exemplary embodiments, without limitation, some or all of the closed loop fans  20  of a unit  10  may be temporarily activated or increased with associated pressure readings to monitor for an associated, expected pressure spike, increase, or other anticipated change. If no such spike, increase, or other anticipated change is detected, a confirmation of the low pressure and/or leak. In exemplary embodiments, without limitations, confirmations may be generated and/or transmitted as a separate electronic notification and/or the transmission and/or generation of the electronic notifications regarding the low pressure or leak alerts may be withheld until such confirmation is received. 
     As another example, without limitation, open loop fans  18  may be deactivated, or speed may be decreased and/or backlight levels increased to generate heat, which would be expected to raise differential pressure. If no such raise is detected, a confirmation of the low pressure/leak may be provided. 
     Confirmation alerting may be provided separately and/or initial alerts to low pressure/leaking may be withheld until confirmation is received. 
     The testing routines, such as of  FIGS.  18 - 20   , may be performed for a single unit  10  and/or multiple units  10 . Alerts, commands, combinations thereof, or the like may be generated and/or transmitted locally and/or at one or more remote facilities and/or devices, such as customer devices and/or an operations center. For example, without limitation, multiple ones of the units  10  may be electronically connected, such as by wired or wireless connection across one or more networks, to a remote network operations center or device associated with one or more of a custom, owner, operator, combinations thereof, or the like of the unit(s)  10 . 
     Any embodiment of the present invention may include any of the features of the other embodiments of the present invention. The exemplary embodiments herein disclosed are not intended to be exhaustive or to unnecessarily limit the scope of the invention. The exemplary embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. Having shown and described exemplary embodiments of the present invention, those skilled in the art will realize that many variations and modifications may be made to the described invention. Many of those variations and modifications will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims. 
     Certain operations described herein may be performed by one or more electronic devices. Each electronic device may comprise one or more processors, electronic storage devices, executable software instructions, and the like configured to perform the operations described herein. The electronic devices may be general purpose computers or specialized computing devices. The electronic devices may comprise personal computers, smartphones, tablets, databases, servers, or the like. The electronic connections and transmissions described herein may be accomplished by wired or wireless means. The computerized hardware, software, components, systems, steps, methods, and/or processes described herein may serve to improve the speed of the computerized hardware, software, systems, steps, methods, and/or processes described herein. The electronic devices, including but not necessarily limited to the electronic storage devices, databases, controllers, or the like, may comprise and/or be configured to hold, solely non-transitory signals.