Abstract:
An inverter ( 10 ) includes a circuit board ( 20 ) including a transformer ( 40 ) disposed thereon, and a shield cage assembly ( 60 ) for enclosing the transformer. The shield cage assembly includes an insulative cage ( 602 ) defining an inner receiving space ( 6028 ) for receiving the transformer, a first conductive cage ( 604 ) defining a first receiving space ( 6048 ) for receiving the insulative cage, and a second conductive cage ( 606 ) defining a second receiving space ( 6068 ) for receiving the first conductive cage. The shield cage assembly blocks EMI emitted by the transformer from interfering with electronic components out of the shield cage assembly, thus enabling the electronic components to perform more reliably.

Description:
1. FIELD OF THE INVENTION 
       [0001]    The invention relates to a shield cage assembly, and particularly to a shield cage assembly and an inverter utilizing the same. 
       2. DESCRIPTION OF RELATED ART 
       [0002]    Inverters are commonly used for converting low voltage direct current (DC) to high voltage alternating current (AC) in liquid crystal display (LCD) monitors. Each inverter includes a circuit board and a transformer disposed on the circuit board. The transformer often emits electromagnetic interference (EMI) at various frequencies during operation. In some cases, the EMI emitted by the transformer are radio frequency (RF) waves. However, electromagnetic waves of various other frequencies may also be emitted by the transformer. 
         [0003]    Such emissions generated by the transformer are problematic because the EMI may adversely affect the performance of other components of the LCD monitors. For instance, the EMI emitted by the transformer may interfere with operations of a touch pad of the LCD monitors. 
         [0004]    Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies. 
       SUMMARY OF THE INVENTION 
       [0005]    An aspect of the invention provides a shield cage assembly. The shield cage assembly is used in an electronic device. The electronic device includes a circuit board and a transformer disposed on the circuit board. The shield cage assembly includes an insulative cage defining an inner receiving space for receiving the transformer, a first conductive cage defining a first receiving space for receiving the insulative cage, and a second conductive cage defining a second receiving space for receiving the first conductive cage. 
         [0006]    Another aspect of the invention provides an inverter. The inverter includes a circuit board including a transformer disposed thereon, and a shield cage assembly for enclosing the transformer. The shield cage assembly includes an insulative cage defining an inner receiving space for receiving the transformer, a first conductive cage defining a first receiving space for receiving the insulative cage, and a second conductive cage defining a second receiving space for receiving the first conductive cage. 
         [0007]    Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an exploded, isometric view of an inverter of an exemplary embodiment of the present invention, including a circuit board, a transformer, and a shield cage assembly; 
           [0009]      FIG. 2  is an exploded, isometric view of the shield cage assembly of  FIG. 1 ; 
           [0010]      FIG. 3  is a partly assembled view of  FIG. 1 , showing a first conductive cage of the shield cage assembly not mounted to the circuit board; 
           [0011]      FIG. 4  is an assembled view of  FIG. 1 , showing a second conductive cage of the shield cage assembly not mounted to the first conductive cage of the shield cage assembly; 
           [0012]      FIG. 5  is a completely assembled view of  FIG. 1  of the exemplary embodiment; and 
           [0013]      FIG. 6  is an exploded, isometric view of a shield cage assembly of another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]      FIG. 1  shows an inverter  10  of the exemplary embodiment of the present invention. The inverter  10 , which is commonly used in a LCD monitor, comprises a circuit assembly like a circuit board  20 , a transformer  40  disposed on the circuit board  20 , and a shield assembly like a shield cage assembly  60  used for enclosing the transformer  40 . The transformer  40  often emits electromagnetic interference (EMI) at various frequencies during operation, and the shield cage assembly  60  is used for blocking the EMI, preventing interference with other components of the LCD monitor. 
         [0015]      FIG. 2  shows the shield cage assembly  60  of the exemplary embodiment. The shield cage assembly  60  comprises an insulative cage  602 , a first conductive cage  604 , and a second conductive cage  606 . 
         [0016]    The insulative cage  602  comprises an inner top plate  6021 , an inner bottom plate  6022 , and a pair of inner sidewalls  6023  perpendicular to the inner top and bottom plates  6021 ,  6022 . The inner top plate  6021 , the inner bottom plate  6022 , and the inner sidewalls  6023  cooperatively bound an inner receiving space  6028  for receiving the transformer  40 . The insulative cage  602  comprises a plastic material, or combination of various plastic materials, that are substantially nonconductive. Exemplary materials for the insulative cage  602  comprise ceramic, epoxy-fiberglass laminate, glass, plastic, polyester, transformer paper, and fishpaper. However, any other material or combination of materials providing a like function as disclosed herein may alternatively be employed. In this exemplary embodiment, the insulative cage  602  is made of polycarbonate. 
         [0017]    The insulative cage  602  further comprises a securing portion  6024  having an adhesive smeared thereon. The securing portion  6024  extends from the inner bottom plate  6022  and is attached to the circuit board  20  by the adhesive for securing the shield cage assembly  60  on the circuit board  20 . 
         [0018]    The first conductive cage  604  comprises a first top plate  6041 , a first bottom plate  6042 , and a first sidewall  6043  perpendicular to the first top and bottom plates  6041 ,  6042 . The first top plate  6041 , the first bottom plate  6042 , and the first sidewall  6043  cooperatively bound a first receiving space  6048  for receiving the insulative cage  602 . The first conductive cage  604  further comprises a fixing portion  6044  secured on the circuit board  20 . The first conductive cage  606  comprises one or more electrically conductive materials. In the exemplary embodiment, the first conductive cage  604  comprises a metallic material, or combination of various metallic materials. Exemplary metallic materials for the first conductive cage  606  substantially comprise copper, aluminum, copper alloy, aluminum alloy and the like. However, any other conductive material, whether metallic or non-metallic, having a like function as disclosed herein may alternatively be employed. 
         [0019]    The second conductive cage  606  comprises a second top plate  6061 , a second bottom plate  6062 , a pair of second sidewalls  6063  perpendicular to the second top and bottom plates  6061 ,  6062 . The second top plate  6061 , the second bottom plate  6062 , and the second sidewalls  6063  cooperatively bound a second receiving space  6068  for receiving the first conductive cage  604 . The second conductive cage  606  comprises one or more electrically conductive materials. In the exemplary embodiment, the second conductive cage  606  comprises a metallic material, or combination of various metallic materials. Exemplary metallic materials for the second conductive cage  606  are tinplate, steel and the like. The metallic material of the second conductive cage  606  is different from the metallic material of the first conductive cage  604 . However, any other conductive material, whether metallic or non-metallic, having a like function as disclosed herein may alternatively be employed. 
         [0020]    Referring to  FIGS. 3-5 . In assembly, the insulative cage  602  is moved toward the circuit board  20  along a horizontal direction X to make the transformer  40  disposed on the circuit board  20  be received in the insulative cage  602 . The securing portion  6024  of the insulative cage  602  is attached to the circuit board  20 , enabling the insulative cage  602  to be stably secured on the circuit board  20 . The first conductive cage  604  is moved toward the circuit board  20  along a horizontal direction Y perpendicular to the horizontal direction X. The fixing portion  6044  of the first conductive cage  604  is secured on the circuit board  20  thus making the first conductive cage  604  be secured on the circuit board  20 . The insulative cage  602  is received in the first receiving space  6048 . The second conductive cage  606  is moved toward the circuit board  20  along the horizontal direction X to make the insulative cage  602  and the first conductive cage  604  be received in the second receiving space  6068 . The second conductive cage  606  is secured on the first conductive cage  604  by a known means such as a soldering process. In an alternative embodiment, the first conductive cage  604  is secured on the insulative cage  602  by an adhesive, and the second conductive cage  606  is also secured on the first conductive cage  604  by an adhesive. 
         [0021]    In operation, the insulative cage  602  of the shield cage assembly  60  serves to electrically insulate the transformer  40  from the first and second conductive cage  604  and  606  thus preventing discharged current from the transformer  40  damaging nearby electronic components. The first conductive cage  604  and the second conductive cage  606  serve to effectively block the EMI emitted by the transformer  40 . In this way, the effective performance of the other components of the LCD monitor, even if they are electromagnetic sensitive components, is ensured. Further, the first conductive cage  604  can further block ambient EMI from interfering with the components enclosed therein. 
         [0022]    In various alternative exemplary embodiments, the metallic material for the first conductive cage  604  is tinplate, steel or the like, while the metallic material for the second conductive cage  606  is copper, aluminum, copper alloy, aluminum alloy or the like, which is still different from the metallic material for the first conductive cage  604 . 
         [0023]      FIG. 6  shows an alternative shield cage assembly  60 ′ of another exemplary embodiment of the present invention. In the exemplary embodiment, the insulative cage  602 ′ comprises a pair of securing portions  6024 ′ extending from opposite ends of the inner bottom plate  6022 ′ respectively. The first conductive cage  604 ′ comprises a first top plate  6041 ′, a first bottom plate  6042 ′, and a first sidewall  6043 ′ perpendicular to the first top plate  6041 ′ and the first bottom plate  6042 ′. The second conductive cage  606 ′ has a similar structure to the first conductive cage  604 ′. Materials used for the shield cage assembly  60 ′ are similar to the above-described shield cage assembly  60 . In assembly, the insulative cage  602 ′ encloses the transformer  40  of  FIG. 1 . The first conductive cage  604 ′ then clips to the insulative cage  602 ′. The second conductive cage  606 ′ then clips to the first conductive cage  604 ′. In this way, the shield cage assembly  60  can provide the same function as disclosed in the above-described exemplary embodiment of  FIG. 1  to  FIG. 5 . 
         [0024]    While exemplary embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only and not by way of limitation. Thus the breadth and scope of the present invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.