Abstract:
The rear cover of an electronics device is made up of two sections including an external heat sink and a rear cover frame. The electronics for the computing device are directly coupled to the heat sink section. The two sections are fastened together with a layer of cushioning material to simultaneously provide shock-vibration protection as well as efficient cooling of the electronics.

Description:
RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application 61/597,312 filed Feb. 10, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates generally to the field of electronics device packaging. More specifically, the present invention is related to a method and apparatus for vibration and shock isolating electronics while maintaining optimal thermal performance as provided by the direct couple heat source to heat sink approach. 
     2. Discussion of Prior Art 
     Displays and computers employed in mission critical shipboard applications must be ruggedized to an extent that they can remain operational after very violent shock and vibration events. These events can occur during combat because of weapon strikes or during any other potentially catastrophic system failure. When these events occur it is vital that critical systems on the ship remain operational. Therefore, the U.S. government has established testing guidelines that simulate these events to ensure that vital electronics are properly designed to meet the requirements. One example standard is MIL-S-901D. There are other similar standards in other countries. 
     In order to pass the required tests to meet MIL-S-901D requirements, most electrical systems need some mechanical protection to limit the degree of shock energy transferred to the components or to strengthen the components sufficiently to survive the energy transferred. Known methods to do this include vibration isolation mounting, rigid encapsulation with sealants or adhesives, heavy mechanical braces &amp; mounting, or combinations of these methods.  FIGS. 1A-B  show a prior art example of internal vibration mounting with internal shock/vibration mounts  10 . 
     These methods all have disadvantages including added weight, cost, and often they increase total footprint of the components being protected. Many times, the internal space required for isolation mounts makes the outside enclosure size unacceptably large for the target application. 
     An additional drawback to the internal shock mounting approach is that it is much harder to transfer the heat from high power components to the outside of the case when the components are shock isolated. Only convection cooling methods can practically be employed. If any direct conduction cooling approaches are attempted, the design runs the risk of transferring significant shock energy to the components. 
     Another technique often employed is to shock isolate the entire sub-assembly, in this case the entire display. In this approach, the scheme to mount the display into the final application is significantly burdened by increased size, weight, complexity and additional cost. This approach does, however provide shock/vibration protection to the electronics while still allowing the electronics to be directly coupled to the external enclosure for better heat dissipation.  FIGS. 2A-C  show a prior art example of external shock mounting with external shock/vibration mount  20 . 
     U.S. Pat. No. 7,254,014 to Cancellieri et al. describes a housing for display electronics with gaskets to provide shock protection and cooling fins on the rear of the assembly. However, Cancellieri et al. do not implement or suggest a floating sub-assembly to protect the internal electronics from shock while simultaneously providing excellent heat transfer to the exterior of the enclosure. 
     U.S. Pat. No. 7,447,034 to Shin describes a sheet of heat conducting material used to isolate any vibrations induced by the electronics from the rest of the case, while still promoting good heat flow to the external case. However, the electronics are still rigidly mounted to the “chassis” base which is then directly mounted to the case of the unit. 
     Whatever the precise merits, features, and advantages of the prior art, none of them achieves or fulfills the purposes of the present invention. 
     SUMMARY OF THE INVENTION 
     A shock/isolation mount is made with a rear enclosure attached to a mounting flange. The rear enclosure also has a heat sink attached to it with cushioning material interposed between the rear enclosure and the heat sink. In one embodiment, the mount houses an electronics board on an electrically insulating polycarbonate platform directly coupled to the heat sink. In one embodiment, the heat sink is attached to the rear enclosure of the mount using shoulder bolts and shock/vibration isolation washers. In another embodiment, the electronics board controls a display, such as a touch screen display, that is also mounted to the mounting flange. 
     A second aspect of this invention is a method for making a shock/isolation mount for an electronics board by interposing cushioning material between the rear enclosure covering the electronics board and a heat sink for the electronics board. In one embodiment, the heat sink is attached to the rear enclosure by shoulder bolts and shock/vibration isolation washers. In another embodiment, the electronics board controls a computer display or a touch screen display, which is also attached to the mounting flange. 
     A preferred embodiment of this invention is a shock/vibration isolation shipboard mount for a touch screen display in a naval ship. The mount allows the display to pass a MIL-S-901D shock test, but does not increase the footprint of the mount over a conventional shipboard mount. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  illustrate a prior art embodiment of an internal shock-vibration mounting. 
         FIGS. 2A-C  illustrate a prior art embodiment of an external shock mounting. 
         FIG. 3  illustrates an external profile view of the present invention. 
         FIG. 4  illustrates a cutaway profile view of the present invention. 
         FIG. 5  illustrates a perspective rear view of the present invention. 
         FIG. 6  illustrates a perspective cutaway view of the present invention. 
         FIG. 7  illustrates a perspective section view of the interior of the present invention. 
         FIG. 8  illustrates a perspective cutaway view of one embodiment of mounting the present invention in a shipboard application. 
         FIG. 9  illustrates a front view of one embodiment of the present invention. 
         FIG. 10  illustrates a rear view of one embodiment of the present invention. 
         FIG. 11  illustrates a side view of one embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides for vibration and shock isolation of packaged electronics within the same mechanical footprint as non-isolated electronics. Preferably the invention will be used as part of a standard platform shipboard display. The package integrates the vibration/shock isolation directly into the mechanical structure of the rear cover of the display. It is anticipated that this approach would support other similar implementations in a variety of enclosure configurations. 
     While this invention is illustrated and described in a preferred embodiment, the device may be produced in many different configurations, forms and materials. There is depicted in the drawings, and will herein be described in detail, a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and the associated functional specifications for its construction and is not intended to limit the invention to the embodiment illustrated. Those skilled in the art will envision many other possible variations within the scope of the present invention. 
       FIGS. 3 and 4  illustrate the profile view of one embodiment of the present invention. The rear cover  100  is broken into two sections  110  and  120 . Section  120  comprises a large heat sink  130  covering the back of the rear cover  100 . Section  110  is the side and corners of the rear cover  100 . The heat sink section  120  is mounted to the outside of the rear enclosure  110  with a layer of cushioning material  140  at the interface. Cushioning material  140  incorporates dual properties of providing a shock-vibration energy absorbing interface as well as providing a rugged environmental seal. In one embodiment, cushioning material  140  comprises medium density cellular foam. 
     When properly mounted, shock energy is transferred through the rear enclosure  110  from the mounting flange  150  but is partially absorbed by the energy absorbing interface  140  before it reaches the heat sink rear section  120  where sensitive electronics  160  are mounted. 
     Inside the cover, the electronics  160  are directly coupled on the rear heat sink section  120  allowing for very efficient conductive cooling of the hot components. The electronics  160  are also protected from shock and vibration as they are mounted only to the rear heat sink section  120 . This accomplishes a solution to the multiple problems of the prior art. 
       FIG. 7  shows a zoomed in cutaway view of the inside of rear cover with rear cover section  120  and heat sink  130  mounted to rear cover section  110  through cushioning material  140 . Section  120  is attached to section  110  with shoulder bolts  180 , which control the compression of cushioning material  140 . The shoulder bolts fit through shock-vibration grommets and have washers to spread the load on section  110 . Heat sources in electronics  160  are directly coupled to blocks  210  on heat sink  130 . Electronics  160  are mounted on polycarbonate platform  170  to electrically isolate the electronics from the metal housing. This assembly ( 160 ,  170 ) is mounted to blocks  220  to maximize protection from the MIL-S-901D shock test. Heat sink  130  sits external to rear cover section  120  to maximize its cooling ability to open air. 
     One embodiment of the present invention provides for mounting a computing device comprising a touch screen LCD in a shipboard mount, as shown in  FIG. 8 . Another embodiment for a touch screen LCD with the shock isolation enclosure of the present invention is shown in  FIGS. 9-11 . 
     CONCLUSION 
     A system has been shown in the above embodiments for the effective implementation of a rear assembly with integrated shock-vibration protection and direct coupled rear heat sink. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention, as defined in the appended claims. For example, the present invention should not be limited by size, materials, environmental requirements, weight, total power, or specific manufacturing techniques. While the described embodiment shows a separately attached heat sink section on the rear cover, other embodiments may, for example, isolate the front portion including a bezel from shock and vibration in an analogous fashion.