Abstract:
A circuit pack housing for providing EMI protection for a circuit pack which may be inserted into an electronics system such as a telecommunications base station cabinet. The circuit pack housing has a single piece plastic design which surrounds the enclosed circuit pack. The internal walls of the circuit pack housing are metalized, and the inner surface of the housing comprises one or more grounding tabs with metalized surfaces. The metalized plastic circuit pack housing also comprises two opposite living hinges and a self latching mechanism, such that when the circuit pack is placed inside the housing and the housing is closed on itself (i.e., with use of the living hinges), the circuit pack is sealed within the housing and protected from EMI thereby. Moreover, the housing may include protruding flexible tabs at the ends thereof, which advantageously seals around the connector which energizes the circuit pack.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of electronics system enclosures such as, for example, telecommunications base station cabinets, and more particularly to a housing for circuit packs installed in such systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    Existing designs for electronics systems such as telecommunications base station cabinets are typically quite bulky because, inter alia, it is necessary that sufficient space exists between the various circuit packs installed therein. In particular, and as is well known to those of ordinary skill in the art, such spacing is needed to provide for EMI (Electromagnetic Interference) protection between nearby circuit packs. This necessarily results in either a limitation on the number of circuit packs that can be installed in a given electronics system and/or an undesirable increase in the size and bulkiness of the system. One alternative approach to the design of electronics systems such as telecommunications base station cabinets which address this problem is to use metal housings around the individual circuit packs in order to provide the necessary EMI protection. However, such metal housings are both expensive and heavy, resulting in not only a significant additional cost, but also often requiring more than one person to install and maintain such systems. It would, therefore, be highly advantageous to provide for electronics systems such as telecommunications base station cabinets which are able to have the circuit packs contained therein stacked more closely together than in prior art designs, but without the need for expensive and heavy metal housings to provide EMI protection. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides a novel housing for circuit packs which may, for example, be inserted into an electronics system such as, for example, a telecommunications base station cabinet. In accordance with an illustrative embodiment of the present invention, a circuit pack housing having a single piece plastic design surrounds a circuit pack and advantageously provides EMI protection thereof. In particular, all of the internal walls of this illustrative circuit pack housing are advantageously metalized, and the inner surface of the housing advantageously comprises one or more grounding tabs with metalized surfaces, thereby grounding the circuit pack. 
         [0004]    In accordance with one illustrative embodiment of the present invention, the metalized plastic circuit pack housing also advantageously comprises two opposing living hinges and a self latching mechanism, such that when the circuit pack is placed inside the housing and the housing is closed on itself (i.e., with use of the living hinges), the circuit pack is advantageously sealed within the housing and protected from EMI thereby. Moreover, in addition with an illustrative embodiment of the present invention, the housing may advantageously include protruding flexible tabs at the ends thereof, which advantageously seals around the connector which energizes the circuit pack. This sealing feature advantageously prevents corrosion from taking place. 
         [0005]    Note that, in accordance with certain illustrative embodiments of the present invention, no fasteners are employed, thereby advantageously minimizing the cost of the circuit pack housing as well as the installation time thereof. Moreover, the additional EMI protection provided in accordance with the above-described illustrative embodiments of the present invention advantageously enables one to stack circuit packs more closely together and hence minimize the size of the telecommunications base station cabinet or other electronics system in which the circuit packs are installed. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a front view of a prior art telecommunications base station electronics system having circuit packs installed therein. 
           [0007]      FIG. 2  shows a front view of a telecommunications base station electronics system having circuit packs enclosed within circuit pack housings for EMI protection installed therein in accordance with an illustrative embodiment of the present invention. 
           [0008]      FIG. 3  shows a top view of a circuit pack enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention. 
           [0009]      FIG. 4  shows a side view of a circuit pack enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention. 
           [0010]      FIG. 5  shows a top view of a circuit pack partially enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention, wherein one side of the circuit pack housing is opened. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]      FIG. 1  shows a front view of a prior art telecommunications base station electronics system. The prior art system of  FIG. 1  includes a number of component sections (i.e., shelves), and comprises antennae  11  (two are shown), a shelf comprising filters  12 , a shelf comprising amplifiers  14 , and a shelf comprising circuit packs  16 , as well as fan tray  13  (positioned between the shelf comprising filters  12  and the shelf comprising amplifiers  14 ), and fan tray  15  (positioned between the shelf comprising amplifiers  14  and the shelf comprising circuit packs  16 ). 
         [0012]    As can be seen in the figure, circuit packs  16  may be installed in their corresponding shelf with use of slotted openings in the top and bottom portions of the shelf, thus allowing the circuit packs to be slid into place. Also, as is typical, the back sides of many of the included components may be connected to either a cabling harness or, preferably, a PWB (Printed Wiring Board) backplane (which is not visible in the figure). Note that in order to provide EMI protection for each of circuit packs  16 , a significant amount of space is required between each adjacent pair of circuit packs  16 , thereby limiting the number of such circuit packs which may be included in the shelf and/or increasing the bulkiness of the resultant system. 
         [0013]      FIG. 2  shows a front view of a telecommunications base station electronics system having circuit packs enclosed within circuit pack housings for EMI protection installed therein in accordance with an illustrative embodiment of the present invention. The illustrative telecommunications base station electronics system of  FIG. 2  includes a number of component sections (i.e., shelves), and comprises antennae  21  (two are shown), a shelf comprising filters  22 , a shelf comprising amplifiers  24 , and a shelf comprising circuit packs  26 , as well as fan tray  23  (positioned between the shelf comprising filters  22  and the shelf comprising amplifiers  24 ), and fan tray  25  (positioned between the shelf comprising amplifiers  24  and the shelf comprising circuit packs  26 ). 
         [0014]    Although not visible, it may be assumed that the back sides of many of these components are advantageously connected to a PWB (Printed Wiring Board) backplane. Moreover, in order to provide EMI protection in accordance with the principles of the present invention, each of circuit packs  26  is advantageously enclosed in a corresponding circuit pack housing  27 , which is constructed in accordance with an illustrative embodiment of the present invention. Also, as can be seen in the figure, circuit packs  26 , together with their corresponding circuit pack housings  27 , are advantageously installed in their corresponding shelf with use of slotted openings in the top and bottom portions of the shelf, thus allowing the circuit packs (together with their corresponding circuit pack housings) to be slid into place. 
         [0015]      FIG. 3  shows a top view of a circuit pack enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention. As shown in the figure, circuit pack  30 , which includes circuit pack connector  31 , is fully enclosed within illustrative circuit pack housing  32 . Note that circuit pack connector  31  is advantageously provided to connect circuit pack  30  to the system backplane in order to energize the circuit pack. (Also shown in the figure is corresponding backplane connector  38  into which circuit pack connector  31  is to be inserted, as well as backplane/system ground  39 .) 
         [0016]    Circuit pack housing  32  comprises plastic casing  33 , which advantageously includes two “living” hinges  34  molded therein. (See description of  FIG. 5  below for a detailed discussion of “living” hinges  34 .) Circuit pack housing  32  also advantageously comprises metalized inner surface  35 , which advantageously has a plurality of metalized circuit pack grounding tabs  36  physically attached and electrically connected thereto. Each of metalized circuit pack grounding tabs  36  are advantageously positioned such that they provide grounding of circuit pack  30  at a corresponding plurality of locations. That is, grounding tabs  36  are advantageously located so that, when circuit pack housing  32  is closed around circuit pack  30 , grounding tabs  36  make physical and electrical contact with grounding paths provided on the surface of circuit pack  30 . 
         [0017]    In accordance with the illustrative embodiment of the present invention shown in  FIG. 3 , circuit pack housing  32  also comprises a plurality (two are shown) of protruding grounding and sealing tabs  37  which are advantageously flexible so that they can be operated in order to affix circuit pack connector  31  into backplane connector  39 . Moreover, grounding and sealing tabs  37  are advantageously metalized and electrically connected to metalized inner surface  35 , in order to advantageously connect and seal the circuit pack ground to backplane/system ground  39  when operated to affix circuit pack connector  31  into backplane connector  39 . Such a sealing feature advantageously prevents corrosion from taking place. 
         [0018]    In accordance with one illustrative embodiment of the present invention, the plastic casing of the circuit pack housing may, for example, comprise a nylon-based plastic such as, for example, grilamid®. (Grilamid® is a nylon-based polyamide  12  injection moulding and extrusion material product from, and a registered trademark of, EMS-Chemie (Asia) Ltd, and is fully familiar to those skilled in the art.) Also, in accordance with one illustrative embodiment of the present invention, the area surrounding circuit pack connecter  31  may be advantageously filled with silicone gel in order to provide improved sealing between circuit pack connector  31  and backplane connector  39 . 
         [0019]    Additionally, in accordance with one illustrative embodiment of the present invention, metalized circuit pack grounding tabs  36  may comprise tabs made of metalized plastic. That is, as is well known to those skilled in the art, metal may be sprayed onto a plastic material so that the material advantageously becomes electrically conducting, and yet still retains many of the advantages of a plastic material (such as, for example, its light weight). 
         [0020]      FIG. 4  shows a side view of a circuit pack enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention. In particular, the figure shows circuit pack  30  enclosed within circuit pack housing  32 . 
         [0021]      FIG. 5  shows a top view of a circuit pack partially enclosed within a circuit pack housing for EMI protection in accordance with an illustrative embodiment of the present invention, wherein one side of the circuit pack housing is opened. In particular, as shown in the figure, circuit pack  30  is partially enclosed within illustrative circuit pack housing  32 , which has one of its two sides in an opened position with respect to circuit pack  30 . 
         [0022]    As can be clearly seen in  FIG. 5 , illustrative circuit pack housing  32  comprises plastic casing  33  which advantageously includes two “living” hinges  34  molded therein. Specifically, these “living” hinges may, for example, comprise a curved notch molded directly into the plastic of plastic casing  33 , thereby advantageously allowing that portion of the plastic casing itself to be operable as a hinge. The use of such “living’ hinges, fully familiar to those of ordinary skill in the art, advantageously minimizes the cost of the circuit pack housing as well as the associated assembly and installation time. 
         [0023]    In accordance with other illustrative embodiments of the present invention, separate physical hinges (i.e., mechanical devices which are attached to plastic casing  33 ) may alternatively be used. In addition, although the illustrative embodiment of the present invention as shown herein comprises two “living” hinges, in accordance with other illustrative embodiments of the present invention, a different number of hinges—whether “living” hinges or separate physical hinges—may be used. For example, it will be obvious to those of ordinary skill in the art that a circuit pack housing with just a single operable hinge may be devised in accordance with the principles of the present invention. 
         [0024]    In accordance with one illustrative embodiment of the present invention, the illustrative circuit pack housing shown in  FIG. 5  also advantageously comprises latch  51  and corresponding latch receptacle  52 , which together operate to enable circuit pack housing  32  to completely enclose circuit pack  30  when closed (i.e., when latch  51  is inserted into latch receptacle  52 ). Thus, when closed, circuit pack housing  32  serves to seal circuit packet  30 , and, in accordance with the principles of the present invention, thereby serves to protect the circuit pack from EMI (e.g., as a result of grounded metalized inner surface  35 , which fully surrounds circuit pack  30  when circuit pack housing  32  is fully closed). Advantageously, the latching mechanism (i.e., latch  51  and latch receptacle  52 ) may, like the “living” hinges described above, be molded directly into the plastic of plastic casing  33 . This also advantageously minimizes the cost of the circuit pack housing as well as the associated assembly and installation time. However; in accordance with other illustrative embodiments of the present invention, separate physical latching mechanisms (i.e., mechanical devices which are attached to plastic casing  33 ) may alternatively be used. 
       Addendum to the Detailed Description 
       [0025]    It should be noted that all of the preceding discussion merely illustrates the general principles of the invention. It will be appreciated that those skilled in the art will be able to devise various other arrangements, which, although not explicitly described or shown herein, embody the principles of the invention, and are included within its spirit and scope. In addition, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. It is also intended that such equivalents include both currently known equivalents as well as equivalents developed in the future—i.e., any elements developed that perform the same function, regardless of structure.