Electronic display with cooling

#The exemplary embodiments described herein generally relate to cooling systems and in particular to cooling systems for electronic displays.

#Conductive and convective heat transfer systems for electronic displays generally attempt to remove heat from the electronic components in a display through the sidewalls of the display. In order to do this, the systems of the past have relied primarily on fans for moving internal air (or ingested ambient air) within the housing past the components to be cooled and out of the display. These components are typically power supplies. In some cases, the heated air is moved into convectively thermal communication with fins.

#While such heat transfer systems have enjoyed a measure of success in the past, improvements to displays and new display applications require even greater cooling capabilities. Electronic displays are now being used in outdoor environments and other applications where they may be exposed to high ambient temperatures and even direct sunlight. In particular, cooling devices for electronic displays of the past have generally used convective heat dissipation systems that function to cool only the rear interior portion of the display. 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. Also, when displays are used in outdoor environments the ambient air may contain contaminates (dust, dirt, pollen, water vapor, smoke, etc.) which, if ingested into the display for cooling the interior can cause damage to the interior components of the display.

#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:

#FIG. 1 is a rear perspective view of an embodiment where the rear cover of the display has been removed.

#FIG. 2A is a perspective section view of another embodiment showing the closed loop and open loop channels.

#FIG. 1 shows the rear of an embodiment for an electronic display 100, where the rear cover for the display housing has been removed in order to show the internal components. In this embodiment, the fan assemblies 102 and 103 for the closed loop may be placed along two opposing edges of a heat exchanger 101. Preferably, fan assembly 102 is the inlet for the heat exchanger and fan assembly 103 is the exit for the heat exchanger 101. These assemblies can optionally be reversed however, where fan assembly 103 is the inlet and fan assembly 102 is the exit. Further, both assemblies 102 and 103 are not required. Some embodiments may use only one fan assembly for the closed loop. If only one fan assembly is used, it may be preferable to place the fan assembly at the inlet of the heat exchanger 101, so that the circulating gas is ‘pulled’ across the front of the image assembly and pushed through the heat exchanger 101. This is not required however; other embodiments may pull the isolated gas through the heat exchanger 101. Other embodiments may push the isolated gas across the front of the image assembly. Fan assemblies 104 and 105 for the open loop may be placed along two opposing edges of the display housing. Again, both assemblies 104 and 105 are not required as some embodiments may use only one assembly and may use the open loop fan assemblies in a push or pull design. Because the various fan assemblies described herein can be placed in multiple orientations, when referring to the placement of the various fan assemblies, the terms ‘push’, ‘pull’, ‘force’, and ‘draw’ will be used interchangeably and any orientation may be used with the various embodiments herein.

#The circulating gas which is being forced by the closed loop fan assemblies is primarily circulating around the display. For example, the gas travels in a loop where it passes through a channel, contacting the front surface of the image assembly (see FIGS. 2A-2B) and absorbs heat from the image assembly. The circulating gas is then preferably directed (or forced) into the heat exchanger 101 in order to transfer heat from the circulating gas to the ambient gas. Afterwards, the circulating gas exits the heat exchanger 101 and may eventually return to the channel and contact the front surface of the image assembly. The circulating gas may also pass over several electronic components 110 in order to extract heat from these devices as well. The electronic components 110 may be any components or assemblies used to operate the display including, but not limited to: transformers, circuit boards, resistors, capacitors, batteries, power modules, motors, inductors, illumination devices, wiring and wiring harnesses, lights, thermo-electric devices, and switches. In some embodiments, the electrical components 110 may also include heaters, when the display assembly might be used in cold-weather environments.

#In order to cool the circulating gas (as well as optionally cooling a backlight assembly or image assembly) ambient gas is ingested into the display housing by the open loop fan assembly 104 and/or 105. The ambient gas may simply be ambient air which is surrounding the display. In some embodiments, the ambient gas may be air conditioned (or otherwise cooled) prior to being drawn into the display. Once the ambient gas is ingested into the display, it may be directed (or forced) through the heat exchanger 101 and optionally also across the rear surface of the backlight assembly or image assembly (see FIGS. 2A-2B). By using the heat exchanger 101, heat may be transferred from the circulating gas to the ambient gas. The heated ambient gas may then be expelled out of the display housing.