CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s).101120471 filed in Taiwan, R.O.C. on Jun. 7, 2012, the entire contents of which are hereby incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to HomePlugs, and more particularly, to a HomePlug with a changeable top case structure. 
       BACKGROUND OF THE INVENTION 
       [0003]    A conventional HomePlug capable of voltage transformation or functional expansion comprises: a hole or slot configured for insertion by a plug; and a case formed integrally as a unitary structure. For example, the conventional HomePlug capable of functional expansion applies Power Line Communication (PLC) for performing Internet surfing and data transmission, and works in conjunction with a data communication network built from an existing power line framework present in an indoor environment, such as a home, an office, a hospital. Hence, Unlike VDSL/ADSL, Power Line Communication (PLC) does not require constructing an additional circuit network for building a new communication network; instead, Power Line Communication (PLC) allows a user to install a HomePlug directly on an indoor alternating current (AC) electric outlet, such that an electronic device, such as a computer or a cell phone, can be electrically connected to the HomePlug for carrying out data transmission, and enables data communication between the devices thus connected, thereby providing a local area network-based communication framework and allowing the devices to share their accessible resources. 
         [0004]    In general, a HomePlug comprises a casing and a circuit board received in the casing, wherein the circuit board has a plug and a socket. A socket assembly is disposed on the casing of a conventional HomePlug. Slots and/or holes which meet socket specifications set forth by various countries are disposed on the socket assembly and adapted to be inserted by plugs of corresponding specifications. The socket assembly and the casing of the conventional HomePlug are formed integrally as a unitary structure by means of a die, such that the socket assembly is fixed to the casing. Hence, from a manufacturer&#39;s perspective, mold opening and mass production have to be carried out anew to the casing having a new socket assembly in order to produce HomePlugs of different specifications, thereby resulting in an intricate lengthy design process, requiring much manpower, and incurring a high cost. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an objective of the present invention to provide a HomePlug with a changeable top case structure so as to change a variety of casings and thereby reduce the required manpower and costs. 
         [0006]    In order to achieve the above and other objectives, the present invention provides a HomePlug with a changeable top case structure. The HomePlug comprises: a casing having a first coupling portion therein and an opening; and a socket assembly having a second coupling portion coupled to the first coupling portion, thereby allowing the socket assembly to be corresponding in position to the opening, coupled to the casing from inside, and exposed from the opening. 
         [0007]    As regards the HomePlug, the first coupling portion and the second coupling portion are a heat stake and a jointing hole, respectively, so as to be corresponding in position to and coupled to each other by heating and melting. 
         [0008]    As regards the HomePlug, the first coupling portion and the second coupling portion are an engagement hook and an alignment hole, respectively, so as to be corresponding in position to and coupled to each other in a separable manner. 
         [0009]    As regards the HomePlug, the socket assembly has slots and/or holes that meet requirements of European Standard sockets, British Standard sockets, German Standard sockets, Australian Standard sockets, or American Standard sockets. 
         [0010]    As regards the HomePlug, the casing further comprises a plurality of heat dissipation vents. 
         [0011]    As regards the HomePlug, the casing further comprises a first case and a second case corresponding in position to and coupled to the first case. 
         [0012]    As regards the HomePlug, the first case and the second case are coupled together by means of ultrasonic melting fusion, engagement, snap-engagement, etc. 
         [0013]    Accordingly, in an embodiment of the present invention, a HomePlug with a changeable top case structure assumes a variety of appearance by changing a variety of casings without redesigning the casings and constituent elements therein. Alternatively, in another embodiment of the present invention, a HomePlug is capable of changing socket assemblies of different specifications and the corresponding circuit designs and thereby applicable to various socket specifications without redesigning a casing in its entirety, so as to dispense with the manpower, dies, and material-related costs which might otherwise be required for manufacturing the casing anew, enhance ease of product design, and increase assembly universality. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Objectives, features, and advantages of the present invention are hereunder illustrated with specific embodiments in conjunction with the accompanying drawings, in which: 
           [0015]      FIG. 1  is an exploded view of a socket assembly and a casing of a HomePlug according to an embodiment of the present invention; 
           [0016]      FIG. 2  is a schematic view of the socket assembly coupled to the casing according to an embodiment of the present invention; 
           [0017]      FIG. 3  is a partial schematic view of the socket assembly coupled to the casing in  FIG. 2 ; and 
           [0018]      FIG. 4  is a schematic view of the casing of HomePlug according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring to  FIG. 1  through  FIG. 4 , there are shown diagrams of a HomePlug  1  with a changeable top case structure according to the present invention.  FIG. 1  is an exploded view of a socket assembly and a casing of a HomePlug according to an embodiment of the present invention.  FIG. 2  is a schematic view of the socket assembly coupled to the casing according to an embodiment of the present invention.  FIG. 3  is a partial schematic view of the socket assembly coupled to the casing in  FIG. 2  according to an embodiment of the present invention. Finally,  FIG. 4  is a schematic view of the casing of HomePlug according to an embodiment of the present invention. 
         [0020]    In an embodiment of the present invention, the HomePlug  1  with a changeable top case structure comprises a casing  10  and a socket assembly  20 . The casing  10  has a first coupling portion  12  therein and an opening  11 . The socket assembly  20  has a second coupling portion  21  coupled to the first coupling portion  12 , thereby allowing the socket assembly  20  to be corresponding in position to the opening  11 , coupled to the casing  10  from inside, and exposed from the opening  11 . 
         [0021]    In this embodiment, the first coupling portion  12  and the second coupling portion  21  are a heat stake and a jointing hole, respectively, so as to be corresponding in position to and coupled to each other by heating and melting. Referring to  FIG. 3 , the first coupling portion  12  is penetratingly disposed in the second coupling portion  21  to allow the first coupling portion  12  and the second coupling portion  21  to be melted and jointed, such that the socket assembly  20  is fixed to the inner surface of the casing  10  and exposed from the opening  11 . 
         [0022]    This embodiment and the accompanying drawings are illustrative rather than restrictive of the way of coupling the first coupling portion  12  and the second coupling portion  21  together. For example, the first coupling portion is an engagement hook disposed on the inner surface of the casing  10 , whereas the second coupling portion is an alignment hole disposed at the socket assembly  20  and coupled to the engagement hook. Hence, the first coupling portion  12  is penetratingly disposed in and snap-engaged with the second coupling portion  21 , thereby allowing the socket assembly  20  to be corresponding in position to the opening  11 , coupled to the casing  10  from inside, and exposed from the opening  11 . 
         [0023]    In another illustrative embodiment, the first coupling portion  12  and the second coupling portion  21  are threaded screw holes penetrated by and meshed with screws, such that the casing  10  and the socket assembly  20  are coupled together. Preferably, instead of penetrating the casing  10 , the first coupling portion  12  is formed in the casing  10  without penetrating the casing  10 ; in other words, the first coupling portion  12  opens on one of the two opposing sides of the casing  10  only, that is, preferably on the inner side of the casing  10  only. In the aforesaid preferred embodiment, for example, the depth of the first coupling portion  12  equals a half of the thickness of the casing  10 . Hence, the screws and the first coupling portion  12  are invisible from outside the casing  10 . 
         [0024]    In this embodiment, the casing  10  further comprises a first case  101  and a second case  102  corresponding in position to and coupled to the first case  101 . The first case  101  and the second case  102  are coupled together by means of ultrasonic melting fusion. Specifically speaking, the edge of the first case  101  is aligned with the edge of the second case  102  such that the first and second cases  101 ,  102  are fitted to each other to form a receiving space (not shown) therebetween, and then the first case  101  and the second case  102  are coupled together by means of ultrasonic melting fusion. Alternatively, engagement structures (such as a flange, an engagement sheet, or an engagement post) which match each other are formed at the edge of the first case  101  and the edge of the second case  102 , respectively, such that the first case  101  and the second case  102  can be coupled together by the engagement structures. Furthermore, snap-engagement structures (such as stepwise edges) which match each other are formed at the edge of the first case  101  and the edge of the second case  102 , respectively, such that the first case  101  and the second case  102  can be coupled together by the snap-engagement structures. Furthermore, the casing  10  further comprises a plurality of heat dissipation vents  103 . Although the heat dissipation vents  103  are disposed on the lateral sides and the top side of the first case  101  as shown in the diagram, the present invention is not limited thereto. In a variant embodiment, the heat dissipation vents  103  can be disposed at any portion of the casing  10 , provided that heat generated from a circuit board (not shown) disposed in the casing  10  and the circuit-related components is dissipated efficiently. 
         [0025]    In an exemplary embodiment of the present invention, the socket assembly  20  has holes which match two round pins typical of a European Standard socket, but the socket assembly  20  of the present invention is not limited thereto. In practice, the slots and/or holes of the socket assembly  20  of the present invention can also match three round pins typical of a British Standard socket, two non-parallel flat blades typical of an Australian Standard socket, two flat blades typical of an American Standard socket, or two flat blades and a round pin (i.e., the grounding pin) of a socket. 
         [0026]    As mentioned earlier, in an embodiment of the present invention, the HomePlug  1  further comprises the circuit board (not shown) disposed inside the receiving space in the casing  10 . A circuit (not shown) is disposed on the circuit board and adapted to electrically connect the socket assembly  20 , a plug assembly  30 , and a network port  40 , thereby providing functional expansion by means of Power Line Communication (PLC) or Power Line Networking (PLN). In practice, a user plugs the HomePlug  1  into an indoor alternating current (AC) electric outlet, connects an external electronic device (such as a personal computer, a notebook computer, a tablet computer, or a smartphone) serving a communication purpose to the network port  40  via a network transmission cable, and thereby enables data transmission to take place by means of the HomePlug  1  and a Power Line Network (PLN). Alternatively, the circuit board comprises the socket assembly  20 , the plug assembly  30 , and a wireless communication module element, such that the user plugs the HomePlug  1  into an indoor alternating current (AC) electric outlet, connects an external electronic device (such as a personal computer, a notebook computer, a tablet computer, or a smartphone) capable of communication to the HomePlug  1  by wireless transmission, and thereby enables data transmission to take place by means of the HomePlug  1  and a Power Line Network (PLN). In this embodiment of the present invention, the pins of the plug assembly  30  are exemplified by two round pins typical of a European Standard plug, but the plug assembly  30  of the present invention is not limited thereto; instead, the slots and/or holes of the plug assembly  30  can be three round pins as set forth by British Standards, two non-parallel flat blades as set forth by Australian Standards, two flat blades as set forth by American Standards, or two flat blades plus a round pin (i.e., the grounding pin). 
         [0027]    Accordingly, in an embodiment of the present invention, a HomePlug with a changeable top case structure assumes a variety of appearance by changing a variety of casings without redesigning the casings and constituent elements therein. Alternatively, in another embodiment of the present invention, a HomePlug is capable of changing socket assemblies of different specifications and the corresponding circuit designs and thereby applicable to various socket specifications without redesigning a casing in its entirety, so as to dispense with the manpower, dies, and material-related costs which might otherwise be required for manufacturing the casing anew, enhance ease of product design, and increase assembly universality. 
         [0028]    The present invention is disclosed above by preferred embodiments. However, persons skilled in the art should understand that the preferred embodiments are illustrative of the present invention only, but should not be interpreted as restrictive of the scope of the present invention. Hence, all equivalent modifications and replacements made to the aforesaid embodiments should fall within the scope of the present invention. Accordingly, the legal protection for the present invention should be defined by the appended claims.
A HomePlug with a changeable top case structure includes a casing and a socket assembly. The casing has a first coupling portion therein and has an opening. The socket assembly has a second coupling portion for coupling with the first coupling portion, such that the socket assembly corresponds in position to the opening and thereby is coupled to the casing from inside and exposed from the opening. The HomePlug with a changeable top case structure is effective in dispensing with redesign and the manufacturing of a casing in its entirety, cutting die and material costs, enhancing ease of product design, and increasing assembly universality.