Abstract:
A system and method for cooling an electronic image assembly having a plurality of cooling gas pathways place behind the electronic image assembly. A first fan may be used to force cooling gas through a first grouping of cooling gas pathways while a second fan may be used to force cooling gas through a second grouping of cooling gas pathways. Temperature sensing devices may be positioned so as to measure the temperature of the first and second groupings of cooling gas pathways. The speeds of the first and second fans may be adjusted based on the temperature measurements of the cooling gas pathway groupings. Additional fans with additional temperature sensing devices may be used for further accuracy and control over the temperature gradients of the electronic image assembly. Manifolds may be used to distribute/collect cooling gas to/from the cooling gas pathways.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/179,996 filed on Jul. 11, 2011, now U.S. Pat. No. U.S. application Ser. No. 13/179,996, issued on Feb. 5, 2013. U.S. application Ser. No. 13/179,996 is a non-provisional application of U.S. Application No. 61/362,854 filed on Jul. 9, 2010. U.S. application Ser. No. 13/179,996 is also a continuation-in-part of U.S. application Ser. No. 12/706,652 filed on Feb. 16, 2010, now U.S. Pat. No. 8,358,397, issued Jan. 22, 2013. U.S. application Ser. No. 13/179,996 is also a continuation-in-part of U.S. application Ser. No. 12/905,704 filed on Oct. 15, 2010. U.S. application Ser. No. 13/179,996 is also a continuation-in-part of U.S. application Ser. No. 12/952,745 filed on Nov. 23, 2010. U.S. application Ser. No. 13/179,996 is also a continuation-in-part of U.S. application Ser. No. 13/100,580 filed on May 4, 2011. U.S. application Ser. No. 13/179,996 is also a continuation-in-part of U.S. application Ser. No. 13/100,556 filed on May 4, 2011. All aforementioned applications are hereby incorporated by reference in their entirety as if fully cited herein. 
     
    
     TECHNICAL FIELD 
       [0002]    Exemplary embodiments generally relate to cooling systems and in particular to cooling systems for electronic displays. 
       BACKGROUND OF THE ART 
       [0003]    Improvements to electronic displays now allow them to be used in outdoor environments for informational, advertising, or entertainment purposes. While displays of the past were primarily designed for operation near room temperature, it is now desirable to have displays which are capable of withstanding large surrounding environmental temperature variations. For example, some displays are capable of operating at temperatures as low as −22 F and as high as 113 F or higher. When surrounding temperatures rise, the cooling of the internal display components can become even more difficult. 
         [0004]    Additionally, modern displays have become extremely bright, with some backlights producing 1,000-2,000 nits or more. Sometimes, these illumination levels are necessary because the display is being used outdoors, or in other relatively bright areas where the display illumination must compete with other ambient light. In order to produce this level of brightness, illumination devices and electronic displays may produce a relatively large amount of heat. 
         [0005]    Still further, in some situations radiative heat transfer from the sun through a front display surface can also become a source of heat. In some locations 800-1400 Watts/m 2  or more through such a front display surface is common. Furthermore, the market is demanding larger screen sizes for displays. With increased electronic display screen size and corresponding front display surfaces, more heat will be generated and more heat will be transmitted into the displays. 
         [0006]    Exemplary modern displays have found some effective means for cooling the displays including circulating a closed loop of gas around the display and drawing ambient gas through the display so that the closed loop of gas may be cooled (as well as portions of the electronic display). Various thermal communications have been discovered which can transfer heat away from the sensitive electronic components and out of the display. Heat exchangers were found to produce an excellent means for transferring heat between the closed loop of gas and the ambient gas. However, previous designs for moving the gas through the display have been found to generate an undesirable amount of noise emission from the display as well as thermal gradients where portions of the display were cooled but others remained warm. 
         [0007]    When using LCD displays, it was found that backlights were often a source of heat and it was desirable to move gas across the rear surface of the backlight in order to cool it. While desirable, it was thought that the front surface of the backlight could not be cooled for fear that the backlight cavity would become contaminated with dust, dirt, or other particulate. 
       SUMMARY OF THE EXEMPLARY EMBODIMENTS 
       [0008]    Exemplary embodiments use a combination of circulating gas and ambient gas in order to adequately cool an electronic display. Circulating gas may be used to remove heat from the front of the image assembly. When using a LCD as the electronic image assembly, circulating gas may also be used to remove heat from the backlight cavity of the LCD. Because the gas is only circulating within the display, it can remain free of particulate and contaminates and will not harm the display. 
         [0009]    Ambient gas may be ingested into the display in order to cool the circulating gas. The ambient gas and the circulating gas may be drawn through a heat exchanger which will allow the heat to transfer from the circulating gas to the ambient gas, preferably without letting the ambient and circulating gases mix with one another. An exemplary embodiment would use a cross-flow heat exchanger. An additional flow of ambient gas can be drawn across the rear surface of the image assembly to remove heat from the rear portion of the image assembly. When using a LCD as the electronic image assembly, this additional flow of ambient gas can be used to remove heat from the rear portion of the backlight for the LCD. 
         [0010]    In order to reduce noise emissions, the fans which drive the ambient and/or circulating gas through the heat exchanger may be placed within the heat exchanger, which can then act as a muffler and reduce the noise emitted by the fans. Further, if using the additional ambient gas pathway behind the image assembly, a manifold may be used to collect the ambient gas along an edge of the display and distribute this into a number of smaller flows. The fans for driving this additional ambient gas pathway can be placed within the manifold in order to reduce the noise emitted by the fans and provide an even distribution of ambient gas across the display. 
         [0011]    It has been found that ingesting ambient gas from the top or bottom edge of the display is preferable as these edges are not typically observable to the viewer. However, when ingesting ambient gas from the top or bottom of a portrait-oriented display, it has been found that as the cool ambient gas travels across the rear portion of the electronic image assembly and accepts heat it increases in temperature. Once the cooling air reaches the opposite edge (either top or bottom), it may have increased in temperature substantially and may no longer provide adequate cooling to the opposing portion of the display. Thus, the manifolds herein allow for cool ambient air to adequately cool the entire electronic image assembly in an even manner and reduce any ‘hot spots’ within the electronic image assembly. 
         [0012]    In order to further reduce any ‘hot spots’ within the electronic image assembly, a plurality of temperature sensors can be placed behind the electronic image assembly in order to determine the temperature at various points behind the electronic image assembly. The fans which drive the optional additional ambient gas pathway can be in electrical communication with the temperature sensors so that the rate of air flow created by the fans can be individually adjusted to account for areas within the display that are at an elevated temperature. The efficiency of the display is increased while ensuring a consistent temperature gradient across the electronic image assembly. 
         [0013]    The foregoing and other features and advantages will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A better understanding of an exemplary embodiment will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and in which: 
           [0015]      FIG. 1A  provides a front perspective view of an exemplary embodiment of the electronic display. 
           [0016]      FIG. 1B  provides a rear perspective view of an exemplary embodiment of the electronic display. 
           [0017]      FIG. 2  provides a rear perspective view similar to that shown in  FIG. 1B  where the rear cover has been removed. 
           [0018]      FIG. 3  provides a perspective sectional view along the A-A section line shown in  FIG. 1B . 
           [0019]      FIG. 4  provides a perspective sectional view along the B-B section line shown in  FIG. 1B . 
           [0020]      FIG. 5  provides a perspective sectional view of insert C shown in  FIG. 4 . 
           [0021]      FIG. 6  provides a perspective sectional view of one embodiment of the cross through plate. 
           [0022]      FIG. 7  provides an exploded perspective view of one embodiment of the heat exchanger. 
           [0023]      FIG. 8  provides a perspective sectional view of another embodiment which uses a flow of circulating gas through the backlight cavity of a liquid crystal display (LCD). 
           [0024]      FIG. 9  provides a perspective sectional view of an exemplary embodiment which uses a flow of circulating gas through the backlight cavity in addition to the flow of circulating gas between the LCD and front plate. 
           [0025]      FIG. 10  provides a perspective sectional view along the A-A section line shown in  FIG. 1B  showing an embodiment with temperature sensors within the channels which may be placed immediately behind the electronic image assembly. 
           [0026]      FIG. 11  provides a rear perspective view similar to that shown in  FIG. 1B  where the rear cover has been removed showing an embodiment where each fan is individually controlled based on the temperature sensor data. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIG. 1A  provides a front perspective view of an exemplary embodiment of the electronic display  100 . A transparent front plate  10  is placed on the front portion of the display to protect the internal components and allow the images produced by the display  100  to be seen. Some embodiments may use glass as the transparent front plate  10 . Exemplary embodiments may use two pieces of glass laminated with index-matching optical adhesive. Some front plates  10  may provide other utility such as anti-reflection or polarizing functions. An inlet aperture  24  and exit aperture  25  may be provided in the housing so that the display  100  can accept ambient gas for cooling the display  100 . 
         [0028]      FIG. 1B  provides a rear perspective view of an exemplary embodiment of the electronic display  100 . A rear cover  15  may be used to provide access to the internal components of the display  100 . 
         [0029]      FIG. 2  provides a rear perspective view similar to that shown in  FIG. 1B  where the rear cover  15  has been removed. Ambient gas  200  may be ingested into the display through the inlet aperture  24  and pass through a heat exchanger  45  and exit the display through the exit aperture  25 . The ambient gas  200  may be drawn into the display and forced through the heat exchanger  45  using heat exchanger fan assembly  46 . An exemplary placement for the heat exchanger fan assembly  46  is discussed further below, but in many embodiments the fan assembly  46  can be placed near the inlet aperture  24  and/or exit aperture  25  and may or may not be placed within the heat exchanger  45  (as shown in  FIG. 2 ). 
         [0030]    Optionally, ambient gas  210  may also be ingested into the display through inlet aperture  24 . Ambient gas  210  may then be directed through a first manifold  30  which travels along the edge of the display. The first manifold  30  accepts the single larger inlet flow of ambient gas  210  and distributes it into a plurality of smaller flows across the display. A second manifold  35  may be placed along the opposite edge of the display as the first manifold  30 . The second manifold  35  accepts the plurality of smaller flows and combines them into a single flow and exhausts it out of the exit aperture  25 . In this embodiment, a manifold fan assembly  211  is used to draw the ambient gas  210  into the inlet aperture  24  and force the ambient gas  210  across the display. For this particular embodiment, the manifold fan assembly  211  is placed within the first manifold  30  and is used to draw the ambient gas  210  into the display as well as distribute the single flow into a plurality of smaller flows. This is not required however, as some embodiments may place the manifold fan assembly  211  in the second manifold  35 , or within both the first and second manifolds  30  and  35 . 
         [0031]    While both flows of ambient gas may be used in an exemplary embodiment, there is no requirement that they are both used. Some embodiments may use only ambient gas  200  or ambient gas  210 . Also, if using both flows of ambient gas  200  and ambient gas  210  there is no requirement that they share the same inlet and exit apertures. Thus, there may be separate inlet and exit apertures for the two flows of ambient gas. 
         [0032]      FIG. 3  provides a perspective sectional view along the A-A section line shown in  FIG. 1B . Again, ambient gas  200  may be ingested into the display through the inlet aperture  24  and pass through a heat exchanger  45  and exit the display through the exit aperture  25 . The ambient gas  200  may be drawn into the display and forced through the heat exchanger  45  using heat exchanger fan assembly  46 . Obviously, the inlet aperture  24  may contain a filter or other coverings so that contaminates, insects, garbage, and/or water/fluids cannot easily be ingested into the display. However, an exemplary embodiment would not be damaged if the ambient gas  200  contained contaminates as they would only pass through the heat exchanger  45  which may not be susceptible to damage from particulate or contaminates. Exit aperture  25  may also contain some type of covering to ensure that contaminates and/or insects could not enter the display. 
         [0033]    An electronic image assembly  50  may be placed behind the front plate  10 . A plurality of channels  60  may be placed immediately behind the electronic image assembly  50 . Ambient gas  210  may be forced through the channels  60  after travelling through the first manifold  30  (not shown here). The flow of ambient gas  210  immediately behind the electronic image assembly  50  may be used to remove any buildup of heat from the rear portion of the electronic image assembly  50 . It may be preferable to have a thermally conductive surface on the rear portion of the electronic image assembly  50  so that heat can easily transfer to this plate and be removed by the ambient gas  210 . 
         [0034]    The channels  60  can take on any number of forms. Although shown in this embodiment with a square cross-section this is not required. Other embodiments may contain channels  60  with I-beam cross-sections, hollow square cross-sections, hollow rectangular cross-section, solid rectangular or solid square cross-sections, ‘T’ cross-sections, ‘Z’ cross-sections, a honeycomb cross-section, or any combination or mixture of these. The channels  60  are preferably thermally conductive and also preferably in thermal communication with the electronic image assembly  50 . Thus, in a preferred embodiment, heat which accumulates on the rear portion of the electronic image assembly  50  may be transferred throughout the channels  60  and removed by ambient gas  210 . 
         [0035]      FIG. 4  provides a perspective sectional view along the B-B section line shown in  FIG. 1B . In this view, the path of the circulating gas  250  can also be observed. The space between the front plate  10  and the electronic image assembly  50  may define a front channel  251 , through which the circulating gas  250  may travel in order to remove any accumulation of heat on the front surface of the electronic image assembly  50 . The circulating gas  250  is preferably then directed into the heat exchanger  45  where heat may be transferred from the circulating gas  250  to the ambient gas  200 . Upon exiting the heat exchanger  45 , the circulating gas  250  may be re-directed into the front channel  251 . The circulating gas  250  may also be directed over various electronic components  7  so that heat may be transferred from the electronic components  7  to the circulating gas  250 . The electronic components  7  could be any one of the following but not limited to: power modules, heat sinks, capacitors, motors, microprocessors, hard drives, AC/DC converters, transformers, or printed circuit boards. 
         [0036]    Also shown in this sectional view is the path of the ambient gas  210  travelling down one of the channels  60  directly behind the electronic image assembly  50 . In this embodiment, the ambient gas  210  is forced out of the first manifold  30 , across the channels  60 , and into the second manifold  35  by manifold fan assembly  211 . As shown in this Figure, the paths of the ambient gas  210  and the circulating gas  250  will likely cross, but it is preferable to keep the two gases from mixing (as the ambient gas  210  may contain particulate or contaminates while the circulating gas  250  can remain substantially free of particulate and contaminates). It may be preferable to keep the circulating gas  250  from having particulate or contaminates because it travels in front of the electronic image assembly  50 . Thus, to keep the image quality from being impaired, it may be desirable to keep the circulating gas  250  clean and prevent it from mixing with the ambient gas  210 . 
         [0037]      FIG. 5  provides a perspective sectional view of insert C shown in  FIG. 4 . As noted above, if practicing an embodiment which uses ambient gas  210  as well as the circulating gas  250 , the pathways of the two gases may need to cross over one another and it may be desirable to prohibit them from mixing to prevent contamination of sensitive portions of the display. Here, cross through plate  500  allows the pathways of the two gases to cross over one another without letting them mix together. The cross through plate  500  in this embodiment contains a series of voids which pass through the plate. A first series of voids  550  passes through the cross through plate  500  and allows ambient gas  210  to travel from the first manifold  30  into the channels  60  which run behind the electronic image assembly  50 . A second series of voids  525  pass through the cross through plate  500  in a direction substantially perpendicular to that of the first series of voids  550 . The second series of voids  525  allows the circulating gas to exit the front channel  251 , cross over the ambient gas  210 , and continue towards the heat exchanger  45 . In this embodiment, a circulating gas fan assembly  255  is used to draw the circulating gas  250  through the front channel  251  and through the heat exchanger  45 . Much like the other fan assemblies shown and described here, the circulating gas fan assembly  255  could be placed anywhere within the display, including but not limited to the entrance/exit of the heat exchanger  45  or the entrance/exit of the front channel  251 . 
         [0038]      FIG. 6  provides a perspective sectional view of one embodiment of the cross through plate  500 . In this embodiment, the cross through plate  500  is comprised of a plurality of hollow blocks  503  sandwiched between a top plate  501  and bottom plate  502  with sections of the plates  501  and  502  removed to correspond with the hollow sections of the blocks  503 . A portion of the top plate  501  has been removed to show the detail of the hollow blocks  503 , first series of voids  550 , and second series of voids  525 . The cross through plate  500  could take on any number of forms and could be constructed in a number of ways. Some other embodiments may use a solid plate where the first and second series of voids  550  and  525  are cut out of the solid plate. Other embodiments could use two sets of hollow blocks where the hollow sections are perpendicular to each other and the blocks are fastened together. Still other embodiments could use a design similar to those that are taught below for the heat exchanger  45 , for example any type of cross-flow heat exchanger design could be used. 
         [0039]      FIG. 7  provides an exploded perspective view of one embodiment of the heat exchanger  45 . In this view, the heat exchanger fan assembly  46  is shown removed from its mounted position within the heat exchanger  45 . In this embodiment, the heat exchanger  45  is divided into two sections  47  and  48  where the fan assembly  46  is placed between the two sections  47  and  48 . While the fan assembly  46  can be placed anywhere so that it draws ambient gas  200  through the heat exchanger  45 , it has been found that placing the fan assembly  46  between the two sections of the heat exchanger can provide a number of benefits. First, the volumetric flow rate of the ambient gas  200  through the heat exchanger is high, which results in better cooling capabilities for the heat exchanger  45 . Second, the noise produced by the fan assembly  46  can be drastically reduced because the surrounding sections  47  and  48  of the heat exchanger  45  essentially act as a muffler for the fan assembly  46 . In this embodiment, section  48  is thinner and longer than section  47 . This was done in order to free up more space within the housing so that additional electronic components could fit within the housing (adjacent to section  48 ). This design may be preferable when it is desirable to create the largest possible heat exchanger  45  (for maximum cooling abilities). This is of course not required, and other embodiments may have sections which are of equal width and length. Also, although this embodiment uses the fan assembly  46  to drive the ambient gas  200 , other embodiments could use a fan assembly placed within the heat exchanger to drive the circulating gas  250  instead and drive the ambient gas  200  with another fan assembly (possibly placed within the heat exchanger or located at the entrance/exit of the heat exchanger). 
         [0040]    The ambient gas  200  travels through a first pathway (or plurality of pathways) of the heat exchanger  45  while the circulating gas  250  travels through a second pathway (or plurality of pathways) of the heat exchanger  45 . Although not required, it is preferable that the circulating gas  250  and ambient gas  200  do not mix. This may prevent any contaminates and/or particulate that is present within the ambient gas  200  from harming the interior of the display. In a preferred embodiment, the heat exchanger  45  would be a cross-flow heat exchanger. However, many types of heat exchangers are known and can be used with any of the embodiments herein. The heat exchanger  45  may be a cross-flow, parallel flow, or counter-flow heat exchanger. In an exemplary embodiment, the heat exchanger  45  would be comprised of a plurality of stacked layers of thin plates. The plates may have a corrugated, honeycomb, or tubular design, where a plurality of channels/pathways/tubes travel down the plate length-wise. The plates may be stacked such that the directions of the pathways are alternated with each adjacent plate, so that each plate&#39;s pathways are substantially perpendicular to the pathways of the adjacent plates. Thus, ambient gas or circulating gas may enter an exemplary heat exchanger only through plates whose channels or pathways travel parallel to the path of the gas. Because the plates are alternated, the circulating gas and ambient gas may travel in plates which are adjacent to one another and heat may be transferred between the two gases without mixing the gases themselves (if the heat exchanger is adequately sealed, which is preferable but not required). 
         [0041]    In an alternative design for a heat exchanger, an open channel may be placed in between a pair of corrugated, honeycomb, or tubular plates. The open channel may travel in a direction which is perpendicular to the pathways of the adjacent plates. This open channel may be created by running two strips of material or tape (esp. very high bond (VHB) tape) between two opposite edges of the plates in a direction that is perpendicular to the direction of the pathways in the adjacent plates. Thus, gas entering the heat exchanger in a first direction may travel through the open channel (parallel to the strips or tape). Gas which is entering in a second direction (substantially perpendicular to the first direction) would travel through the pathways of the adjacent plates). 
         [0042]    Other types of cross-flow heat exchangers could include a plurality of tubes which contain the first gas and travel perpendicular to the path of the second gas. As the second gas flows over the tubes containing the first gas, heat is exchanged between the two gases. Obviously, there are many types of cross-flow heat exchangers and any type would work with the embodiments herein. 
         [0043]    An exemplary heat exchanger may have plates where the sidewalls have a relatively low thermal resistance so that heat can easily be exchanged between the two gases. A number of materials can be used to create the heat exchanger. Preferably, the material used should be corrosion resistant, rot resistant, light weight, and inexpensive. Metals are typically used for heat exchangers because of their high thermal conductivity and would work with these embodiments. However, it has been discovered that plastics and composites can also satisfy the thermal conditions for electronic displays. An exemplary embodiment would utilize polypropylene as the material for constructing the plates for the heat exchanger. It has been found that although polypropylene may seem like a poor thermal conductor, the large amount of surface area relative to a small sidewall thickness, results in an overall thermal resistance that is low. Thus, an exemplary heat exchanger would be made of plastic and would thus produce a display assembly that is thin and lightweight. Specifically, corrugated plastic may be used for each plate layer where they are stacked together in alternating fashion (i.e. each adjacent plate has channels which travel in a direction perpendicular to the surrounding plates). 
         [0044]      FIG. 8  provides a perspective sectional view of another embodiment which uses a flow of circulating gas  350  through the backlight cavity of a liquid crystal display (LCD)  300 . In this embodiment, a LCD  300  and an associated backlight  320  are used as the electronic image assembly. A backlight wall  330  may be placed between the LCD  300  and the backlight  320  in order to enclose the area and create a backlight cavity. Typically, the backlight cavity is closed to prevent contaminates/particulate from entering the backlight cavity and disrupting the optical/electrical functions of the backlight  320 . However, as discussed above the exemplary embodiments may use a clean gaseous matter for the circulating gases which could now be used to ventilate the backlight cavity in order to cool the backlight  320  and even the rear portion of the LCD  300 . An opening  340  can be placed in the backlight wall  330  to allow circulating gas  350  to flow through the backlight cavity. A fan assembly  360  may be used to draw the circulating gas  350  through the backlight cavity. In an exemplary embodiment there would be an opening on the opposing backlight wall (on the opposite side of the display as shown in this figure) so that circulating gas  350  could easily flow through the backlight cavity. 
         [0045]      FIG. 9  provides a perspective sectional view of an exemplary embodiment which uses a flow of circulating gas  350  through the backlight cavity in addition to the flow of circulating gas  250  between the LCD  300  and front plate  10 . Circulating fan assembly  255  may be placed so that it can draw circulating gas  350  through the backlight cavity as well as circulating gas  250  between the LCD  300  and the front plate  10 . As discussed above, the circulating gases  250  and  350  are preferably forced through the heat exchanger  45  (not shown in this figure) so that they may be cooled by the ambient gas  200  (also not shown in this figure). 
         [0046]    Also shown in  FIG. 9  is the optional additional flow of ambient gas  210  which may travel immediately behind the backlight  320 . Once travelling through the first manifold  30 , the ambient gas  210  may pass through the channels  60  in order to remove heat from the backlight  320  and even the channels  60  themselves (if they are thermally conductive). The manifold fan assembly  211  may be used to draw the ambient gas  210  into the first manifold  30  and through the channels  60 . Again, the cross though plate  500  may be used to allow the circulating gases  350  and  250  to cross paths with the ambient gas  210  without letting the two gases mix. 
         [0047]      FIG. 10  provides a perspective sectional view along the A-A section line shown in  FIG. 1B  showing an embodiment with temperature sensors  800  within the channels  60  which may be placed immediately behind the electronic image assembly  50 . It has been found that different portions of the electronic image assembly  50  and/or channels  60  may be warmer than others. This can be due to sunlight which contacts only a portion of the display, heat transfer from power supplies (depending on their location), and the general propensity for heat to rise. By placing temperature sensors  800  within the channels  60 , it is possible to measure the temperature at many different places within the display and adjust the flow rate for the various fans to accommodate the temperature measurements. It may be preferable to place each temperature sensor  800  in the air flow pathway for a corresponding fan so that temperature feedback can be adequately addressed by the appropriate fan. 
         [0048]      FIG. 11  provides a rear perspective view similar to that shown in  FIG. 1B  where the rear cover has been removed showing an embodiment where each fan  850  is individually controlled based on the data from temperature sensors  800 . For this particular embodiment, there is one fan  850  for each temperature sensor  800 . Further for this particular embodiment, each temperature sensor  800  is placed in the air flow pathway for each corresponding fan  850 . This is not required however, as other embodiments may place multiple temperature sensors within the air flow pathway of one fan or multiple fans may be forcing cooling air across a single temperature sensor. 
         [0049]    The temperature sensors  800  and fans  850  may be in electrical communication with a microcontroller, CPU, and/or microprocessor  875 . Many types of these devices are commonly available and known in the art, including but not limited to Field-programmable gate array (FPGA), field-programmable analog array (FPAA), application-specific integrated circuit (ASIC), programmable read-only memory (PROM), programmable logic devices (PLDs), complex programmable logic device (CPLD), and any other electrical device which is capable of executing logic commands. A desired operating temperature range can be selected and the fans  850  may be individually engaged for only the regions which require cooling (as indicated by the temperature sensors  800 ). This embodiment allows the display for further reduce any ‘hot spots’ and accurately control the cooling of the display in an efficient manner. 
         [0050]    In an exemplary embodiment, the backlight  320  would contain a plurality of LEDs mounted on a thermally conductive substrate (preferably a metal core PCB). On the surface of the thermally conductive substrate which faces the channels  60  there may be a thermally conductive front plate which may be in thermal communication with the channels  60 . In an exemplary embodiment, the thermally conductive plate would be metallic and more preferably aluminum. 
         [0051]    As noted above, many electronic image assemblies (especially LEDs, LCDs, and OLEDs) may have performance properties which vary depending on temperature. When ‘hot spots’ are present within an image assembly, these hot spots can result in irregularities in the resulting image which might be visible to the end user. Thus, with the embodiments described herein, the heat which may be generated by the image assembly (sometimes containing a backlight assembly) can be distributed (somewhat evenly) throughout the channels  60  and thermally-conductive surfaces to remove hot spots and cool the backlight and/or electronic image assembly. 
         [0052]    The circulating gases  250  and  350 , ambient gas  200 , and optional ambient gas  210  can be any number of gaseous matters. In some embodiments, air may be used as the gas for all. Preferably, because the circulating gases  250  and  350  are in front of the image assembly and backlight respectively, they should be substantially clear, so that they will not affect the appearance of the image to a viewer. The circulating gases  250  and  350  should also preferably be substantially free of contaminates and/or particulate (ex. dust, dirt, pollen, water vapor, smoke, etc.) in order to prevent an adverse effect on the image quality and/or damage to the internal electronic components. It may sometimes be preferable to keep ambient gases  200  and  210  from having contaminates as well. Filters may be used to help reduce the particulate within ambient gases  200  and  210 . Filters could be placed near the inlet aperture  24  so that ambient gases  200  and/or  210  could be drawn through the filter. However, in an exemplary embodiment the display may be designed so that contaminates could be present within the ambient gases  200  and  210  but this will not harm the display. In these embodiments, the heat exchanger  45 , manifolds  30  and  35 , channels  60 , and any other pathway for ambient or circulating gas should be properly sealed so that any contaminates in the ambient gas would not enter sensitive portions of the display. Thus, in these exemplary embodiments, ingesting ambient air for the ambient gases  200  and  210 , even if the ambient air contains contaminates, will not harm the display. This can be particularly beneficial when the display is used in outdoor environments or indoor environments where contaminates are present in the ambient air. 
         [0053]    The cooling system may run continuously. However, if desired, temperature sensing devices may be incorporated within the electronic display to detect when temperatures have reached a predetermined threshold value. In such a case, the various cooling fans may be selectively engaged when the temperature in the display reaches a predetermined value. Predetermined thresholds may be selected and the system may be configured to advantageously keep the display within an acceptable temperature range. Typical thermostat assemblies can be used to accomplish this task. Thermocouples may be used as the temperature sensing devices. 
         [0054]    It is to be understood that the spirit and scope of the disclosed embodiments provides for the cooling of many types of displays. By way of example and not by way of limitation, embodiments may be used in conjunction with any of the following electronic image assemblies: LCD (all types), light emitting diode (LED), organic light emitting diode (OLED), field emitting display (FED), light emitting polymer (LEP), organic electro luminescence (OEL), plasma displays, and any other thin panel electronic image assembly. Furthermore, embodiments may be used with displays of other types including those not yet discovered. In particular, it is contemplated that the system may be well suited for use with full color, flat panel OLED displays. Exemplary embodiments may also utilize large (55 inches or more) LED backlit, high definition liquid crystal displays (LCD). While the embodiments described herein are well suited for outdoor environments, they may also be appropriate for indoor applications (e.g., factory/industrial environments, spas, locker rooms) where thermal stability of the display may be at risk. 
         [0055]    As is well known in the art, electronic displays can be oriented in a portrait manner or landscape manner and either can be used with the embodiments herein. 
         [0056]    Having shown and described preferred embodiments, those skilled in the art will realize that many variations and modifications may be made to affect the described embodiments and still be within the scope of the claimed invention. Additionally, many of the elements indicated above may be altered or replaced by different elements which 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.