Abstract:
A passive cooling arrangement for an electronic housing assembly is provided. The assembly includes a frame disposed in the housing assembly; a circuit board supported in the frame; a heat generating component disposed on the circuit board; and a heat sink configured with a substantially flat peripheral portion and a depression portion. The substantially flat peripheral portion faces and is nearly coextensive with an outer wall of said housing assembly, and the depression portion is in thermal engagement with the heat generating component on the circuit board. The frame includes a base having embosses which support the circuit board in a position enabling thermal engagement of the heat generating component and the depression portion of the heat sink. The outer wall of the housing assembly is preferably unvented and the housing assembly is preferably oriented in use with the outer wall facing upwardly.

Description:
This application claims the benefit, under 35 U.S.C. §365 of International Application PCT/US2011/000,319, filed 22 Feb. 2011, which was published in accordance with PCT Article 21(2) on 1 Sep. 2011, in English and which claims the benefit of U.S. Provisional Application Ser. No. 61/338,907 filed 25 Feb. 2010. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application Ser. No. 61/338,907 filed Feb. 25, 2010, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to quiet set-top boxes having improved heat dissipating capabilities. 
     BACKGROUND OF THE INVENTION 
     Set-top boxes continue to be in high demand and an ever increasing need exists to reduce the size and improve aesthetic appeal, performance, and robustness of these devices and the like. 
     Particular problems that set-top boxes face are damage due to liquid entry, insect entry, and heat generation. However, venting apertures, which are often used for heat dissipation, unfortunately increase the opportunity of liquid and insect entry. As such, a need exists to address each of these problems without creating or augmenting other problems. 
     An additional consideration in designing set-top boxes to keep in mind is the consumer preference for smaller set-top boxes that are quiet, attractive, and mechanically and electrically robust that fit in crowded or small entertainment centers. Because heat dissipation fans, which tend to improve electrical robustness of the set-top boxes, introduce noise and increase size of set-top boxes, a need exists for a design which can be robust without fans and yet meet consumer preferences. 
     SUMMARY OF THE INVENTION 
     A set top box is disclosed which comprises: a top heat sink component having a planar peripheral portion surrounding a central depression portion; a circuit board under the top heat sink component, the circuit board having a heat generating component thermally contacting the central depression portion; a frame having a base and embosses, the base being under the circuit board and the embosses contacting and supporting the circuit board; and an outer cover housing an internal assembly which comprises the top heat sink component, circuit board, and frame therein. The outer cover has an upper wall, a lower wall, two outer side walls, a front side and an open end, wherein the open end is configured to enable the internal assembly to be inserted into the outer cover. The frame has two parallel side walls and a back wall, the side walls being parallel to the two outer side walls of the outer cover and the back wall being positioned at the open end of the outer cover, wherein a gap can exist between an entire edge of the planar periphery portion and the side walls and the back wall. An upper gap can also exist between the upper wall of the outer cover and the planar periphery of the top broad heat sink component and a bottom gap can exist between the lower wall of the outer cover and the base of the frame. Alternatively, the planar periphery portion can have a thermal joint between a border of the planar periphery portion and the side walls and the back wall, the base can have apertures, and the set top box can have a plurality of feet attached to an exterior side of the lower wall, wherein the feet are at least 6 mm in height. 
     At least one of the parallel side walls can have a slot and the outer cover has a clip snap adjacent to at least one of the outer side walls, wherein the clip snap is engaged in the slot and locks the internal assembly in the outer cover. The clip snap can be adjacent to the open end and the clip snap preferably has a flexible member directed away from the open end and forming an acute angle with the at least one outer side wall and the clip snap also preferably has a distal end that engages the clip snap in the slot. The clip snap can have a top portion and bottom portion engaged with an edge region of the upper wall and the lower wall, respectively, thereby securing the clip snap within the outer cover. Additionally, the back wall can have an opening aligned with the flexible member and adapted to received a release rod such that the insertion of the release rod causes the distal end to disengage from the slot, thereby permitting the internal assembly to be removed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying figures of which: 
         FIG. 1  shows a series of views of the major components of the set-top box according to the invention; 
         FIG. 2  shows an interior view of the assembled set-top box according to the invention with a front portion of the set top box removed; 
         FIG. 3  shows a cross-sectional view of an alternative design of the set top box according to the invention; 
         FIG. 4  shows the insertion of the inner assembly into a 5-sided outer cover of the set top box; 
         FIG. 5  shows the rear view of the set top box and a top view of the set top box for the application of a cover removal fixture to disassemble the set-top box according to the invention; 
         FIG. 6  is a perspective view of the set top box and cover removal fixture for the disassembly of the set top box according to the invention; 
         FIG. 7  shows an outer cover of the set top box according to the invention; 
         FIG. 8  shows a button assembly that provides a stop to position the frame pan within the outer cover according to the invention; 
         FIG. 9  shows the attachment of the button assembly  58  to the outer wall of the outer cover according to the invention; 
         FIG. 10  shows the attachment of clip snap assemblies at the outer sides of the outer cover according to the invention; and 
         FIG. 11  shows the joining of the top broad heat sink  10  to the frame pan before insertion into the outer cover according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The set-top box  1  or the like according to the invention includes the various components which are shown in  FIG. 1  and includes a top broad heat sink  10 , a main printed circuit board  13 , a frame pan  18 , and an outer cover  28 . 
     More particularly,  FIG. 1A  shows a top broad heat sink  10 , which is an internal component. The top broad heat sink  10  can be a generally contoured plate that has a generally planar periphery  12  and a contoured central feature such as a pocket, central depression, notch, recess, multilevel depression, mesa extending from and/or into a plane of the planar periphery. The central feature or central depression  11  can have side walls extending from the planar periphery and form an obtuse angle therewith. The contoured feature can have a flat bottom designed to contact the main integrated circuit and/or other heat generating component  17 . 
       FIG. 1B  shows a main printed circuit board  13  or the like, which can be generally flat. The main printed circuit board  13  can have a main integrated circuit  17  or the like in a central region and holes  16  for mounting and/or securing the main printed circuit board  13  to a frame pan  18 . Other features of the main printed circuit board are shown in the figure which can include jack panel connectors  15  at one edge and a button cluster  14  at another edge, which can be an opposing edge. The main integrated circuit and other heat generating or hot components  17  can contact the flat bottom or other portion of the central depression  11  of the top broad heat sink  10 , which can be in thermal contact with the other heat generating or hot components through a thermal joint  27  which could be a pad. 
       FIG. 1C  shows a frame pan  18  which can have a rectangular shape and four sides and which can house the main printed circuit board (pc board)  13 . The frame pan  18  has a back wall  21  with jack panel apertures  19  to accommodate jack panel connectors  15  or the like and a base wall or base  22  having embosses  20  for the mounting or securing of the pc board  13  through the holes  16  therein. Additionally, the frame pan can have on the back wall  21  at least one opening  25  therethrough which can be through a portion of the back wall that extends beyond the side walls  23  of the frame pan  18 . Additionally, the side walls  23  can have slots  24  therethrough closer to the end of the side walls that are adjacent to the back wall  21 . The slots  24  are used to lock the frame pan  18  in the outer cover  28 . 
       FIGS. 1D and 1E  show an outer cover  28  of the set top box  1  in an upright position and a rotated upside down position, respectively. The orifices  29  are shown in the front side  30  which can be decorative. The orifices  29  are designed and aligned to accommodate the button cluster  14 . The outer cover  28  further includes an upper wall  31 , lower wall  32 , two outer sides  34 , and an open back  35 . The exterior side of the lower wall  32  can include rubber feet  33  which can be at least 6 mm in height to ensure adequate air entry under the set top box for improved thermal management. The assembled internal components of  FIGS. 1A-1C  are inserted into the outer cover  28  via the open back  35 . 
       FIG. 2  shows a simplified internal view of the set top box  1  in an assembled form with a front portion of the set top box removed. The top broad heat sink  10  having the generally planar periphery  12  and the central depression  11  is shown being in thermal contact with the main pc board  13 . The broad heat sink can extend to cover the top edges of the walls of the frame pan. More specifically, the central depression  11  can thermally contact the main integrated circuit board or other heat generating component  17  on the pc board  13  through a thermal pad joint or contact  27 . The main printed circuit board  13  is shown being mounted and/or secured to embosses  20  of the frame pan  18  by use of screws, bolts or solder pad joints  43  through the holes  16  or contact points in the circuit board  13 , wherein the main printed circuit board  13  is effectively thermally contacting the frame pan  18 . 
     The construction shown in  FIG. 2  generally shows how the heat generated by the components on the pc board  13  is transferred into the top broad heat sink  12  and the frame pan  18  through embosses  20 . The heat spreads out in the pan  18  and then radiates to the inside surface of the outer cover  28 . The outer cover  28  then radiates and convects the heat to the ambient air with no vents or minimal use of vents. 
       FIG. 2  further shows outer gaps  41  between the side walls  23  of the frame pan  18  and the outer side  34  of the outer cover  28 ; inner gaps  40  between the edge of the planar periphery  12  of the top broad heat sink  12  and the side walls  23  of the frame pan  18 ; bottom gap  42  between the lower wall  32  of the outer cover  28  and the base  22  of the frame pan  18 ; and upper gap  44  between the upper wall  31  of the outer cover  28  and the planar periphery  12  of the top broad heat sink  10 . The bottom gap  42  and upper gap  44  prevent the outer cover  28  from overheating. 
       FIG. 3  shows a cross-sectional view of an alternative design of the set top box  1  in which the side wall  23  of frame pan  18  thermally contacts the planar periphery  12  of the top broad heat sink  10  through a thermal joint  45 . 
       FIG. 4  is a perspective view of the set top box  1  showing the insertion of the inner assembly into a 5-sided outer cover  28  of the set top box. The inner assembly comprises the pc board  13  with the top broad heat sink  12  thereon contained within the frame pan  18 . The arrow in  FIG. 4  shows the insertion direction  46  of the inner assembly into the outer cover  28 . 
       FIGS. 5A and 5B  show additional features that can be employed in the set top box according to the invention.  FIG. 5A  is a rear view of the set top box  1  showing the back wall  21  of the pan frame  18  and  FIG. 5B  shows how a cover removal fixture  50  is applied to the back wall  21  to disassemble the set-top box  30  for maintenance, diagnostics, or electronic component upgrading. In particular,  FIGS. 5A and 5B  show a possible layout for the back wall  21  in which two openings  25  are configured to permit two protruding release fingers  51  of the cover removal fixture  50  to enter therethrough. In cases where insect entry is a concern the set top box can be completely sealed from insect entry when no vents are used and the two openings  25  are covered with removable caps which are not shown in the figures. 
       FIG. 5B  shows a top view of the set top box  1  with the upper wall  31  of the outer cover removed and, in particular, shows an additional feature of the outer cover  28  which is that the outer cover can have a clip snap  53  extending from the interior of the outer sides  34  or the outer cover  28  that applies an inwardly force away from the outer walls  34 . The clip snaps  53  do not necessary need to be attached to the out walls, but can be attached to the lower wall  32  or the upper wall  31 . Anyway, the clip snaps  53  align with the slots  24 , which can be alternatively be grooves, of the frame pan  18  such that the inwardly force causes the clip snaps  53  to engage the slots  24  when the frame pan  18  is slid into the outer cover  28 , thereby locking frame pan  18  into the out cover  28 . The clip snaps  53  have a flexible member directed away from the open back wall  35  and forms an acute angle with the outer sides  34 . The clip snaps  53  have a distal end that engage slots  24 . 
     To disassemble the set top box  1 , a forward force  52  is applied to two clip snaps  53  by the release fingers  51  as the release fingers  51  are inserted into the openings  25 . The forward force  52  causes the release fingers  51  to flex outwardly, thereby removing the distal ends of the clip snaps  53  from the slots  24 . Once the clip snaps are removed from the slots  24  with the release fingers  51  applied, the outer cover  28  can easily slide forward, thereby facilitating the removal of the pan frame  18  along with the internal components therein. 
       FIG. 6  is a perspective view of the set top box  1  and cover removal fixture  50  for the disassembly of the set top box  1 . This feature of the set top box  1  requiring the cover removal fixture  50  to disassemble the set-top box  1  helps to ensure that the set top box  1  will only be disassembled by a qualified technician in possession of the cover removal fixture  50 . This perspective view of the cover removal fixture  50  shows clearance  54  in the base of the cover removal fixture  50  to accommodate the jack panel connectors  15  such that the release fingers  51  can be fully inserted into the openings  25  to cause the clip snaps  53  to sufficiently flex. 
       FIG. 7  shows an embodiment of the invention in which the outer cover  28  of the set top box  1  is constructed by having the two outer sides  34  snapped onto the left and right sides of a folded structure that comprises the upper wall  31 , the lower wall  32 , and the front side  30 . The front side  30  optionally has a C-shape that is connected to the parallel upper  31  and lower walls  32 . The outer sides  34  can snap into receiving portions  66  (not shown) on the upper and lower walls  31 ,  32  through holding assemblies  65  on the upper and lower portions of the outer sides  35 .  FIG. 7  further shows clip snap assemblies  55  which attach to the inner sides of the outer walls  34  or alternatively attach to the outer edges of the upper wall  31  and lower wall  32  such that they are adjacent to the outer walls  34 . The clip snaps assemblies can provide the clip snaps  53 , which can be used to hold in the frame pan  18  in final assembly when the frame pan  18  is inserted in the open back  35 .  FIG. 7  further shows a heat stake logo LED shield  56  and a heat stake bezel  57  which can both attach to the outer surface of the front side  30 . Also, shown is a button assembly  58  which also attaches to the inner sides of at least one outer wall  34 . 
       FIG. 8  shows a detailed view of the button assembly  58  and  FIG. 9  shows how the button assembly  58  attaches to the outer wall  34 . The button assembly  58  has a central button  61  at one end of a rod or central member  67  and a stop  62  which can have a rectangular shape. Extending perpendicularly from the rod or central member  67  is an attachment member  68 , which has two opposing elastic grasping members  59  and a locator rib  60 . 
       FIG. 9  further shows how the button assembly  58  attaches to the outer wall  34  by having the button  61  being placed in button receiving hole  63  of the outer wall and simultaneously having the two opposing elastic grasping members  59  snap around the edges of a rib assembly  64  on the outer wall  34 . The rib assembly  64  can have a plate structure that is parallel to the outer wall  34  and spaced therefrom by an attachment spacer  70 . The locator rib  60  of the button assembly  58  slides under a rib  69  of the rib assembly  64  such that button assembly  58  is held into place by having the locator rib  60  and rib  69  in contact while the button  61  is engaged in the hole  63  and by having the two opposing elastic grasping members  59  snapped into place. The stop  62  can then be used to ensure that the frame pan  18  is properly held within the outer cover  28 . 
       FIG. 10  shows how the clip snap assemblies  55  can attach to the outer edges of the upper wall  31  and lower wall and how the outer sides  34  snap onto the sides of a folded structure.  FIG. 10A  shows a perspective view of the attachment and  FIG. 10B  shows a cross sectional view of the attachment of the clip snap assemblies  55  and the outer sides  34 . More particularly,  FIG. 10B  shows the clip snap assembly  55  having hook  71  at its end that hooks through an aperture in the edge of the upper wall  31 . Likewise the clip snap assembly  55  can have another hook  71  at the bottom of the clip snap that hooks through an aperture in the edge of the lower wall  32 , thereby securing the clip snap assembly  55 . 
       FIG. 10B  further shows the holding assembly  65  of the outer wall  34  extending perpendicularly from the inner wall of the outer wall  34  and has an aperture therethrough to permit an edge portion of the upper wall  31  to hook therein. Likewise a similar holding assembly  65  of the outer wall  34  can be present at the bottom of the outer wall and can engage an edge portion of the lower wall  32 , thereby securing the outer wall to the folded structure to form the outer cover  28 . There can be multiple clip snap assemblies on either side of the set top box. The clip snap can have a flexible central member ( 80 ) that directed away from the open back ( 35 ) and forming an acute angle with the outer side ( 34 ) and the clip snap  53  also has a distal end ( 81 ) that engages the slot ( 24 ). 
       FIG. 11  generally shows how top broad heat sink  10  can be joined to the frame pan  18  before insertion into the outer cover  28 .  FIG. 11A  shows that the top broad heat sink  10  can have a lead edge that can be inserted into slots at the top edge of the back wall  21  of the frame pan  18  in insertion direction  74 , which can be at an acute angle with the base of the frame pan  18 .  FIG. 11B  shows that once the lead edge is inserted into the slots, the top broad heat sink  10  can swing in downward motion  75  until the pocket or central depression  11  of the top broad heat sink  10  contacts the thermal pad joint  27  or the main integrated circuit or heat generating component of the main printed circuit board  13 . The main printed circuit board  13  is omitted in  FIG. 11  to more clearly show relationship of the top broad heat sink  10  with the frame pan  18 ; however, the frame pan  18  would have the main printed circuit board  13  therein in the actual application of the invention. Optionally, the frame pan  18  can have a central thermal contact protrusion  73  on the base  22  which can thermally contact the bottom portion of the main integrated circuit or heat generating component of the main printed circuit board  13  or the main printed circuit board  13  itself. Furthermore, the base portion  22  can have a series of apertures as shown to provide additional heat dissipation from the main printed circuit board  13 . 
       FIG. 11C  further shows that the top broad heat sink  10 , which can be aluminum, can have tabs  76  that fit into tab receiving slots in the side walls  23  to properly locate and/or secure the top broad heat sink  10  with the frame pan  18 , which can be steel. Also, shown in  FIG. 11C  is that the top broad heat sink  10  can have a center boss  77  to promote thermal contact with the main printed circuit board  13  and/or components thereon. This contact can be secured with a screw or the like. It can be appreciated that the pocket or central depression  11  can actually have one or more levels of depressions. 
     In a presently preferred embodiment, the set top box has no vents or minimal vents, reduced size, and is adapted to be ergonomically assembled and disassembled. The disclosed product preferably has no fans and has a design that makes the product capable of being unusually compact. The set top box can be just large enough to fit the connectors along its back, the buttons along its front and the internal components. This is achieved by housing the pc board and the hot components in an all encompassing outer cover as disclosed. Additionally, the top and bottom parts of the inner shell assembly which are the top broad heat sink  10  and the base  22  of the frame pan  18  conduct the heat from hot components therein and spread out the heat. Then the parts of the shell radiate the heat to the inner surface of the outer cover  28 . The outer cover  28  radiates and convects the heat to the ambient air. To optimize the radiation, the outer cover can have a flat black finish. 
     The set top box  1  according to the invention can have an external ac to dc power supply that can closely fit to the main pc board  13 . With this design, the set top can effectively dissipate the heat. 
     It should be understood that although examples of the claimed inventions specifically mention set-top boxes and circuit boards, the invention is not limited to these features. For example, the invention is applicable to computers and other electronic devices having heat generating components. Furthermore, the invention is also applicable to electronic parts other than circuit boards which can generate heat.