Abstract:
An exemplary embodiment provides an electronic display having a liquid crystal panel and a rear wall placed behind the liquid crystal panel, said rear wall having a front surface which faces the liquid crystal panel and a rear surface which faces away from the liquid crystal panel, where a space between the liquid crystal panel and the front surface of the rear wall defines a gap. One or more electronic components for driving the electronic display are preferably attached to the rear surface of the rear wall and a fan is preferably positioned to draw ambient air through said gap. A front transparent plate may be positioned in front of the liquid crystal panel to define a gap for accepting circulating gas which preferably does not mix with the ambient air.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/234,360, filed Sep. 19, 2008. U.S. patent application Ser. No. 12/234,360 is a non-provisional of U.S. Provisional Application Nos.; 61/053,713 filed May 16, 2008; 61/039,454 filed Mar. 26, 2008; 61/057,599 filed May 30, 2008; and 61/076,126 filed Jun. 26, 2008. U.S. patent application Ser. No. 12/234,360 is also a continuation in part of U.S. patent application Ser. No. 11/941,728, filed Nov. 16, 2007, now U.S. Pat. No. 8,004,648 issued Aug. 23, 2011. U.S. patent application Ser. No. 12/234,360 is also a continuation in part of U.S. patent application Ser. No. 12/191,834 filed Aug. 14, 2008, now U.S. Pat. No. 8,208,115 issued Jun. 26, 2012. U.S. patent application Ser. No. 12/234,360 is also a continuation in part of U.S. patent application Ser. No. 12/234,307 filed Sep. 19, 2008, now U.S. Pat. No. 8,767,165 issued Jul. 1, 2014. 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 cooling electronic displays and their electronic components. 
       BACKGROUND OF THE ART 
       [0003]    Conductive and convective heat transfer systems for electronic displays are known. These systems of the past generally attempt to remove heat from the electronic components in a display through as many sidewalls of the display as possible. In order to do this, the systems of the past have relied primarily on fans for moving air past the components to be cooled and out of the display. In some cases, the heated air is moved into convectively thermal communication with fins. Some of the past systems also utilize conductive heat transfer from heat producing components directly to heat conductive housings for the electronics. In these cases, the housings have a large surface area, which is in convective communication with ambient air outside the housings. Thus, heat is transferred convectively or conductively to the housing and is then transferred into the ambient air from the housing by natural convection. 
         [0004]    While such heat transfer systems have enjoyed a measure of success in the past, improvements to displays require even greater cooling capabilities. 
       SUMMARY OF THE EXEMPLARY EMBODIMENTS 
       [0005]    In particular, cooling devices for electronic displays of the past have generally used convective heat dissipation systems that function to cool an entire interior of the display by one or more fans and fins, for example. By itself, this is not adequate in many climates, especially when radiative heat transfer from the sun through a display window becomes a major factor. In many applications and locations 200 Watts or more of power through such a display window is common. Furthermore, the market is demanding larger screen sizes for displays. With increased electronic display screen size and corresponding display window size more heat will be generated and more heat will be transmitted into the displays. 
         [0006]    In the past, many displays have functioned satisfactorily with ten or twelve inch screens. Now, many displays are in need of screens having sizes greater than or equal to twenty-four inches that may require improved cooling systems. For example, some outdoor applications call for forty-seven inch screens and above. With increased heat production with the larger screens and radiative heat transfer from the sun through the display window, heat dissipation systems of the past, which attempt to cool the entire interior of the display with fins and fans, are no longer adequate. 
         [0007]    A large fluctuation in temperature is common in the devices of the past. Such temperature fluctuation adversely affects the electronic components in these devices. Whereas the systems of the past attempted to remove heat only through the non-display sides and rear components of the enclosure surrounding the electronic display components, a preferred embodiment causes heat transfer from the face of the display as well. By the aspects described below, embodiments have made consistent cooling possible for electronic displays having screens of sizes greater than or equal to twelve inches. For example, cooling of a 55 inch screen can be achieved, even in extremely hot climates. Greater cooling capabilities are provided by the device and method described and shown in more detail below. 
         [0008]    An exemplary embodiment relates to an isolated gas cooling system and a method for cooling the electronic components of an electronic display. An exemplary embodiment includes an isolated gas cooling chamber. The gas cooling chamber is preferably a closed loop which includes a first gas chamber comprising a transparent anterior plate and a second gas chamber comprising a cooling plenum. The first gas chamber is anterior to and coextensive with the viewable face of the electronic display surface. The transparent anterior plate may be set forward of the electronic display surface by spacers defining the depth of the first gas chamber. A cooling chamber fan, or equivalent means, may be located within the cooling plenum. The fan may be used to propel gas around the isolated gas cooling chamber loop. As the gas traverses the first gas chamber it contacts the electronic display surface, absorbing heat from the surface of the display. Because the gas and the relevant surfaces of the first gas chamber are transparent, the image quality remains excellent. After the gas has traversed the transparent first gas chamber, the gas may be directed into the rear cooling plenum. Located within the rear cooling plenum can be any number of electronic components which may be used to run the display. These components may include but are not limited to: transformers, circuit boards, resistors, capacitors, batteries, power transformers, motors, illumination devices, wiring and wiring harnesses, and switches. 
         [0009]    In order to cool the gas in the plenum, external convective or conductive means may be employed. In at least one embodiment, an external fan unit may be utilized to blow cool air over the exterior surfaces of the plenum. The heat from the warm gas may radiate into the walls of the plenum and then escape the walls of the plenum by convection or conduction or a combination of both. The external fan unit may be positioned at the base of the housing for the entire display. Once the air is heated by flowing over the exterior surfaces of the plenum, the heated air may exit the housing as exhaust. Note, that the air from this external fan should not enter the isolated cooling system as this would introduce dust and contaminates into the otherwise clean air. 
         [0010]    The foregoing and other features and advantages will be apparent from the following more detailed description of the particular embodiments, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    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: 
           [0012]      FIG. 1  is a perspective view of an exemplary embodiment in conjunction with an exemplary electronic display. 
           [0013]      FIG. 2  is an exploded perspective view of an exemplary embodiment showing components of the isolated gas cooling system. 
           [0014]      FIG. 3  is top plan view of an exemplary embodiment of the cooling chamber. 
           [0015]      FIG. 4  is a front perspective view of an embodiment of the isolated cooling chamber, particularly the transparent anterior surface of first gas chamber. 
           [0016]      FIG. 5  is a rear perspective view of an embodiment of the isolated cooling chamber, particularly the cooling plenum. 
           [0017]      FIG. 6  is a rear perspective view of an embodiment of the isolated cooling chamber showing surface features that may be included on the plenum 
           [0018]      FIG. 7  is a top plan view of an exemplary embodiment of the cooling chamber showing surface features that may be included on the plenum. 
           [0019]      FIG. 8  is a front perspective view of an embodiment of the isolated cooling chamber with included thermoelectric modules. 
           [0020]      FIG. 9  is a top plan view of an exemplary embodiment of the cooling chamber with included thermoelectric modules. 
           [0021]      FIG. 10  is an exploded perspective view of an exemplary embodiment showing components of the isolated gas cooling system. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Embodiments relate to a cooling system for the electronic components of an electronic display and to combinations of the cooling system and the electronic display. Exemplary embodiments provide an isolated gas cooling system for an electronic display. Such an isolated gas cooling system is the subject matter of U.S. Application No. 61/033,064, incorporated by reference herein. 
         [0023]    As shown in  FIG. 1 , when the display  10  is exposed to outdoor elements, the temperatures inside the display  10  will vary greatly without some kind of cooling device. As such, the electronics including the display screen (e.g., LCD screen) will have a greatly reduced life span. By implementing certain embodiments of the cooling system disclosed herein, temperature fluctuation is greatly reduced. This cooling capability has been achieved in spite of the fact that larger screens generate more heat than smaller screens. 
         [0024]    The display shown is equipped with an innovative gas cooling system. Accordingly, it may be placed in direct sunlight. Although the cooling system may be used on smaller displays, it is especially useful for larger LCD, LED, or organic light emitting diodes (OLED) displays. These screens, especially with displays over 24 inches, face significant thermoregulatory issues in outdoor environments. 
         [0025]    In  FIG. 1 , the display area of the electronic display shown includes a narrow gas chamber that is anterior to and coextensive with the electronic display surface. The display shown also is equipped with an optional air curtain device  114  which is the subject matter of co-pending U.S. application Ser. No. 11/941,728, incorporated by reference herein. Optionally, the display also has a reflection shield  119 , to mitigate reflection of the sunlight on the display surface. Additionally, in outdoor environments, housing  70  is preferably a color which reflects sunlight. 
         [0026]    It is to be understood that the spirit and scope of the disclosed embodiments includes cooling of displays including, but not limited to LCDs. By way of example and not by way of limitation, exemplary embodiments may be used in conjunction with displays selected from among LCD (including TFT or STN type), light emitting diode (LED), organic light emitting diode (OLED), field emitting display (FED), cathode ray tube (CRT), and plasma displays. 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. While the embodiments described herein are well suited for outdoor environments, they may also be appropriate for indoor applications (e.g., factory environments) where thermal stability of the display may be at risk. 
         [0027]    As shown in  FIG. 2  an exemplary embodiment  10  of the electronic display and gas cooling system includes an isolated gas cooling chamber  20  contained within an electronic display housing  70 . A narrow transparent first gas chamber is defined by spacers  100  and transparent front plate  90 . A second transparent front plate  130  may be laminated to front plate  90  to help prevent breakage of front glass  90 . As shown in  FIG. 2 , cooling chamber  20  may surround LCD stack  80  and associated backlight panel  140 . 
         [0028]    The gas cooling system  10  shown in  FIG. 2  may include means for cooling gas contained within the second gas chamber. These means may include a fan  60  which may be positioned at the base of the display housing  70 . The fan will force the cooler ingested air over the exterior surfaces of a posterior cooling plenum  45 . If desired, an air conditioner (not shown) may also be utilized to cool the air which contacts the external surfaces of plenum  45 . 
         [0029]    Referring to  FIG. 3 , in at least one embodiment the isolated gas cooling chamber  20  comprises a closed loop which includes a first gas chamber  30  (see  FIG. 3 ) and a second gas chamber  40 . The first gas chamber includes a transparent plate  90 . The second gas chamber comprises a cooling plenum  45 . The term “isolated gas” refers to the fact that the gas within the isolated gas cooling chamber  20  is essentially isolated from external air in the housing of the display. Because the first gas chamber  30  is positioned in front of the display image, the gas should be substantially free of dust or other contaminates that might negatively affect the display image. 
         [0030]    Various electronic components  200  are shown in various positions throughout the plenum  45 . Placing these components  200  within the plenum allows for increased air flow around the components  200  and increased cooling. Further, location of the components  200  within the plenum  45  can help satisfy space considerations, as well as manufacturing and repair considerations. These components  200  may be mounted directly on the walls or surfaces of the plenum  45 , or may be suspended by rods or posts  210 . The precise mounting of the components  200  can vary depending on the amount of cooling that is required for the component, manufacturing limitations, wire routing benefits, or ease of repair or replacement of the specific component. Further, the precise wiring of the components  200  can vary depending on similar factors. The wiring may pass through a single hole in the plenum  45  and then spread to each component or there may be various holes in the plenum  45  to accommodate the wiring for each component individually. In a further embodiment, PCB boards and other typical electronic mounting surfaces may be integrated into the plenum  45  such that the mounting board itself substitutes as a portion of the plenum wall. 
         [0031]    The isolated gas may be almost any transparent gas, for example, normal air, nitrogen, helium, or any other transparent gas. The gas is preferably colorless so as not to affect the image quality. Furthermore, the isolated gas cooling chamber need not necessarily be hermetically sealed from the external air. It is sufficient that the gas in the chamber is isolated to the extent that dust and contaminates may not substantially enter the first gas chamber. 
         [0032]    In the closed loop configuration shown in  FIG. 3 , the first gas chamber  30  is in gaseous communication with the second gas chamber  40 . A cooling chamber fan  50  may be provided within the posterior plenum  45 . The cooling fan  50  may be utilized to propel gas around the isolated gas cooling chamber  20 . The first gas chamber  30  includes at least one front glass  90  mounted in front of an electronic display surface  85 . The front glass  90  may be set forward from the electronic display surface  85  by spacers  100  (see  FIG. 4 ). The spacing members  100  define the depth of the narrow channel passing in front of the electronic display surface  85 . The spacing members  100  may be independent or alternatively may be integral with some other component of the device (e.g., integral with the front plate). The electronic display surface  85 , the spacing members, and the transparent front plate  90  define a narrow first gas chamber  30 . The chamber  30  is in gaseous communication with plenum  45  through entrance opening  110  and exit opening  120 . 
         [0033]    As shown in  FIG. 3 , a posterior surface of the first gas chamber  30  preferably comprises the electronic display surface  85  of the display stack  80 . As the isolated gas in the first gas chamber  30  traverses the display it contacts the electronic display surface  85 . Contacting the cooling gas directly to the electronic display surface  85  enhances the convective heat transfer away from the electronic display surface  85 . 
         [0034]    Advantageously, in exemplary embodiments the electronic display surface  85  comprises the posterior surface of the first gas chamber  30 . Accordingly, the term “electronic display surface” refers to the front surface of a typical electronic display (in the absence of the embodiments disclosed herein). The term “viewable surface” or “viewing surface” refers to that portion of the electronic display surface from which the electronic display images may be viewed by the user. 
         [0035]    The electronic display surface  85  of typical displays is glass. However, neither display surface  85 , nor transparent front plate  90 , nor optional second transparent front plate  130  need necessarily be glass. Therefore, the term “glass” will be used herein interchangeably with the term plate. By utilizing the electronic display surface  85  as the posterior surface wall of the gas compartment  30 , there may be fewer surfaces to impact the visible light traveling through the display. Furthermore, the device will be lighter and cheaper to manufacturer. 
         [0036]    Although the embodiment shown utilizes the electronic display surface  85 , certain modifications and/or coatings (e.g., anti-reflective coatings) may be added to the electronic display surface  85 , or to other components of the system in order to accommodate the coolant gas or to improve the optical performance of the device. In the embodiment shown, the electronic display surface  85  may be the front glass plate of a liquid crystal display (LCD) stack. However, almost any display surface may be suitable for embodiments of the present cooling system. Although not required, it is preferable to allow the cooling gas in the first gas chamber  30  to contact the electronic display surface  85  directly. In this way, the convective effect of the circulating gas will be maximized. Preferably the gas, which has absorbed heat from the electronic display surface  85  may then be diverted to the cooling plenum  45  where the collected heat energy in the gas may be dissipated into the air within the display housing  70  by conductive and or convective means. 
         [0037]    To prevent breakage, the optional second surface glass  130  may be adhered to the front surface of glass  90 . Alternatively, surface glass  90  may be heat tempered to improve its strength. As shown in  FIG. 3 , fan  50  propels a current of air around the loop (see arrows) of the isolated gas cooling chamber  20 . The plenum  45  defining the second gas chamber  40  is adapted to circulate the gas behind the electronic display surface  85 . The plenum  45  preferably surrounds most of the heat generating components of the electronic display, for example, backlight panel  140  (e.g., an LED backlight). 
         [0038]      FIG. 4  shows that the anterior surface  90  of the first gas chamber  30  is transparent and is positioned anterior to and at least coextensive with a viewable area of an electronic display surface  85 . The arrows shown represent the movement of the isolated gas through the first gas chamber  30 . As shown, the isolated gas traverses the first gas chamber  30  in a horizontal direction. Although cooling system  20  may be designed to move the gas in either a horizontal or a vertical direction, it is preferable to propel the gas in a horizontal direction. In this way, if dust or contaminates do enter the first gas chamber  30 , they will tend to fall to the bottom of chamber  30  outside of the viewable area of the display. The system may move air left to right, or alternatively, right to left. 
         [0039]    As is clear from  FIG. 4 , to maximize the cooling capability of the system, the first gas chamber  30  preferably covers the entire viewable surface of the electronic display surface  85 . Because the relevant surfaces of the first gas chamber  30  as well as the gas contained therein are transparent, the image quality of the display remains excellent. Anti-reflective coatings may be utilized to minimize specular and diffuse reflectance. After the gas traverses the first gas chamber  30  it exits through exit opening  120 . Exit opening  120  defines the entrance junction into the rear cooling plenum  45 . 
         [0040]      FIG. 5  shows a schematic of the rear cooling plenum  45  (illustrated as transparent for explanation). One or more fans  50  within the plenum may provide the force necessary to move the isolated gas through the isolated gas cooling chamber. Various electronic components  200  can be located anywhere throughout the second gas chamber  40 . Again, these components can be mounted directly on the walls of the chamber or supported on rods or posts  210 . Thus, the cooling plenum  45  can be designed to not only take heat from the first gas chamber  30  but also to take heat from these various electronic components  200 . Plenum  45  may have various contours and features to accommodate the internal structures within a given electronic display application. 
         [0041]    As can be discerned in  FIGS. 6 and 7 , various surface features  150  may be added to improve heat dissipation from the plenum  45 . These surface features  150  provide more surface area to radiate heat away from the gas within the second gas chamber  40 . These features  150  may be positioned at numerous locations on the surfaces of the plenum  45 . These features may be used to further facilitate the cooling of various electronic components  200  which may also be located within the plenum  45 . 
         [0042]    Referring to  FIGS. 8 and 9 , one or more thermoelectric modules  160  may be positioned on at least one surface of the plenum  45  to further cool the gas contained in the second gas chamber  40 . The thermoelectric modules  160  may be used independently or in conjunction with surface features  150 . Alternatively, thermoelectric modules  160  may be useful to heat the gas in the rear plenum if the unit is operated in extreme cold conditions. Thermoelectric modules  160  may also be used to further facilitate the cooling or heating of various electronic components  200  which may also be located within the plenum  45 . 
         [0043]      FIG. 10  shows an exemplary method for removing heat in the gas contained in the rear plenum  45 . Fan  60  may be positioned to ingest external air and blow that air into the display housing  70 . Preferably, the air will contact the anterior and posterior surfaces of the plenum  45 . Furthermore, in this configuration, fan  60  will also force fresh air past the heat generating components of the electronic display (e.g., the TFT layer, backlight, transformers, circuit boards, resistors, capacitors, batteries, power transformers, motors, illumination devices, wiring and wiring harnesses, and switches) to further improve the cooling capability of the cooling system. The heated exhaust air may exit through one or more apertures  179  located on the display housing  70 . In a preferred embodiment, the air from this external fan  60  should not enter the isolated cooling system as this would introduce dust and contaminates into the otherwise clean gas. 
         [0044]    Besides thermoelectric modules  160 , there are a number of ways to cool the gas in the second gas chamber. For example, air conditioners or other cooling means known by those skilled in the art may be useful for cooling the gas contained in plenum  45 . 
         [0045]    While the display is operational, the isolated gas cooling system may run continuously. However, if desired, a temperature sensor (not shown) and a switch (not shown) may be incorporated within the electronic display  10 . The thermostat may be used to detect when temperatures have reached a predetermined threshold value. In such a case, the isolated gas cooling system 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 with a thermostat (not shown) to advantageously keep the display within an acceptable temperature range. 
         [0046]    An optional air filter (not shown) may be employed within the plenum to assist in preventing contaminates and dust from entering the first gas chamber  30 . 
         [0047]    Having shown and described preferred embodiments, those skilled in the art will realize that many variations and modifications may be made to affect the 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 exemplary embodiments. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.