Abstract:
A transformer having a closed magnetic flux path includes at least one bobbin, at least one first winding, at least one second winding, and at least two magnetic cores. The first winding and the second winding are individually wound on the bobbin. The two magnetic cores include an I-shaped magnetic core and an E-shaped magnetic core piercing the inner part of the bobbin to form a closed magnetic flux path in the transformer. When one of the first windings is damaged, the other first winding still operates normally and is unaffected.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a transformer having a closed magnetic flux path. In particular, this invention relates to a transformer having a closed magnetic flux path that is used for driving a plurality of CCFLs.  
         [0003]     2. Description of the Related Art  
         [0004]     As the dimension of LCD devices (such as LCD monitors or LCD TVs) becomes larger, LCD devices need more CCLFs to make the light emitted from the LCD devices brighter and more uniform.  
         [0005]     As shown in  FIG. 1 , when the transformer  1  of the prior art provides a plurality of outputted driving signals, two first windings  11  and two second windings  12  are symmetrically located at single magnetic flux path  13 . Each of the first windings  11  has a set of pins  111 , and each of the second windings  12  has another set of pins  121 . Each of the two first windings  11  are connected with a driving unit (not shown in the figure) via the pins  111 . Similarly, each of the two second windings  12  are connected with a CCFL (not shown in the figure) via the pins  121 . Therefore, the transformer provides two sets of outputted signals. However, when one of the first windings  11  is damaged or becomes decayed, the magnetic flux induced by the magnetic flux path  13  becomes so small that it affects the outputted signal from the two second windings  12 . Therefore, the power supplied to the CCFL is inadequate, and the brightness of the CCFL is affected.  
       SUMMARY OF THE INVENTION  
       [0006]     One particular aspect of the present invention is to provide a transformer having a closed magnetic flux path. The transformer is connected with a plurality of driving units and provides a plurality of outputted signals. Its magnetic flux paths are independent of each other. When one of the first windings is damaged, the outputted signal is unaffected.  
         [0007]     The transformer having a closed magnetic flux path includes at least one bobbin, at least one first winding, at least one second winding, and at least two magnetic cores. The bobbin includes at least two first coil frames and at least one second coil frame. The first winding includes at least two first coils wound on the first coil frame of the bobbin. The second winding includes a plurality of second coils wound on the second coil frame of the bobbin. The two magnetic cores pierce the bobbin to form at least two independent closed magnetic flux paths. Therefore, even though the first coil of one of the closed magnetic flux paths is damaged, the magnetic flux on the other closed magnetic flux path is not changed so the output of the second coil is stable.  
         [0008]     For further understanding of the invention, reference is made to the following detailed description illustrating the embodiments and examples of the invention. The description is only for illustrating the invention and is not intended to be considered limiting of the scope of the claim. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The drawings included herein provide a further understanding of the invention. A brief introduction of the drawings is as follows:  
         [0010]      FIG. 1  is a schematic diagram of the magnetic flux path of the transformer of the prior art;  
         [0011]      FIG. 2  is a schematic diagram of the first embodiment of the present invention;  
         [0012]      FIG. 3  is a schematic diagram of the closed magnetic flux path of the present invention;  
         [0013]      FIG. 4  is a schematic diagram of the closed magnetic flux path and two coils wound in parallel of the present invention;  
         [0014]      FIG. 5  is a schematic diagram of the second embodiment of the present invention;  
         [0015]      FIG. 6  is a schematic diagram of the third embodiment of the present invention;  
         [0016]      FIG. 7  is a schematic diagram of the fourth embodiment of the present invention; and  
         [0017]      FIG. 8  is a schematic diagram of the transformer having a plurality of driving ports and a plurality of output ports of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     Reference is made to  FIG. 2 . The transformer having a closed magnetic flux path  2  includes a bobbin  21 , an E-shaped magnetic core  22 , and an I-shaped magnetic core  23 . The I-shaped magnetic core  23  pierces the inner part of the bobbin  21 . The E-shaped magnetic core  22  is jointed with the I-shaped magnetic core  23  for forming a magnetic flux path  24  having a square-B-shaped (as shown in  FIG. 3 ). The bobbin  21  includes four first coil frames  211  and two second coil frames  212 . A separating-board  213  is located at the center of the bobbin  21  so as to separate the first coil frame  211  from the second coil frame  212 . The first coil frame  211  is located symmetrically with the second coil frame  212 . Two adjacent first coil frames  211  are located near the separating-board  213 . The second coil frames are individually installed at the two sides of the bobbin  21  and are adjacent to the first coil frames  211 . There are a plurality of first pins  214  and second pins  215  at the bobbin  21 . The first pins  214  are adjacent to the first coil frames  21 land the second pins  215  are adjacent to the second coil frames  212 . The first coil frames  211  are wound with a first winding  25  and the second coil frames  212  are wound with a second winding  26  (as shown in  FIG. 3 ). The first pins  214  are connected with the driving units (not shown in the figure) and the second pins  215  are connected with the CCFLs (not shown in the figure).  
         [0019]     Reference is made to  FIG. 3 . The bobbin  21  (as shown in  FIG. 2 ) is wound with two first windings  25  and two second windings  26  so that the two sides of the magnetic flux path  24  have the first winding  25  and the second winding  26  disposed symmetrically. The first winding  25  includes two first coils  251  and a compensating coil  252 . Thereby, the two windings  25  are individually connected with a royer driving unit (not shown in the figure) via the first pin  214  and the two second windings  25  are individually connected with a CCFL via the second pin  215 . When power is inputted into the first winding  25  via the royer driving unit, the magnetic flux path  24  forms two closed magnetic flux paths due to the current flows through the first winding  25  so as to generate magnetic flow. The two second windings  26  react to the magnetic flow to generate a current for driving the CCFLs to light. The compensating coil  252  makes the current generated at the second winding  26  more stable. When one royer driving unit connected with one first winding  25  at one of the closed magnetic flux paths  241  is damaged, an other closed magnetic flux path  241  is neither damaged nor affected because the two closed magnetic flux paths  241  are independent. Therefore, the undamaged closed magnetic flux path  241  enables the CCFL to light stably.  
         [0020]     Reference is made to  FIG. 4 . The first winding  25  includes two first coils  251  and is connected with the driving unit (not shown in the figure) via the first pin  214  using a two wound wires method. The driving unit is a full-bridge, a half-bridge, or a push-pull type. The four first pins  214  of the first coils  251  are individually connected with the current output terminal MOSFET of the driving unit and another MOSFET. The two input pins  214  of the first coils  251  are electrically connected with the current input terminal MOSFET of the push-pull driving unit. The two output pins  214  of the first coils  251  are electrically connected with another MOSFET of the push-pull driving unit. By this method, the undamaged closed magnetic flux path  241  can operate normally and the two wound wires method lowers the collection effect of the first coil  251  and the temperature of the first coil  251  so as to protect the first winding  25 .  
         [0021]     Reference is made to  FIG. 5 . In this embodiment, the transformer having a closed magnetic flux path  2  includes a bobbin  21 , a similar-E-shaped magnetic core  22 ′, and an I-shaped magnetic core  23 . The similar-E-shaped magnetic core  22 ′ includes a U-shaped part  221 ′. Two parallel I-shaped parts  222 ′ extend upward from the center of the bottom of the U-shaped part  221 ′. The I-shaped magnetic core  23  pierces the inner part of the bobbin  21 . The similar-E-shaped magnetic core  22 ′ is jointed with the I-shaped magnetic core  23  for forming a magnetic flux path  24  having a grating-shape. Thereby, two independent closed magnetic flux paths are achieved.  
         [0022]     Reference is made to  FIG. 6 . In this embodiment, the transformer having a closed magnetic flux path  2  includes a bobbin  21 , two E-shaped magnetic cores  22 , and two I-shaped magnetic cores  23 . The two I-shaped magnetic cores  23  are arranged in parallel at the center of the bobbin  21 , are vertical to the bobbin  21  and straddle the bobbin  21 . The center part of the two E-shaped magnetic cores  22  plugs into the bobbin  21  from the two ends of the bobbin  21 . The two sides of the E-shaped magnetic cores  22  are individually jointed with the I-shaped magnetic core  23 . Thereby, two independent closed magnetic flux paths are achieved.  
         [0023]     Reference is made to  FIGS. 7 and 8 . The transformer having a closed magnetic flux path  2  provides a plurality of outputs. In this embodiment, the transformer having a closed magnetic flux path  2  includes two bobbins  21 , four F-shaped magnetic cores  27 , and two I-shaped magnetic cores  23 . The two bobbins  21  are the same as each other. The two I-shaped magnetic cores  23  are arranged in parallel at the center of the bobbin  21 , and are vertical to the bobbin  21  and straddle the bobbin  21 . The F-shaped magnetic cores  27  are individually plugged into the bobbins  21  and are adjacent to each other. The F-shaped magnetic cores  27  are individually jointed with the two I-shaped magnetic cores  23 . The magnetic flux path  24  forms two independent closed magnetic flux paths  241 , as shown in  FIG. 8 . Each of the closed magnetic flux paths  241  includes two first windings  25  and two second windings  26  so as to have multiple inputs and multiple outputs. Each of the closed magnetic flux paths  241  are independent from each other so that single closed magnetic flux paths  241  can output stably.  
         [0024]     The transformer having a closed magnetic flux path prevents the problem of the output of all second windings being affected when the single first winding is damaged. The two wound wires method lowers the collection effect and temperature to protect the first winding. Furthermore, collocating a variety of magnetic cores achieves the effect of having multiple inputs and multiple outputs and forms a plurality of magnetic flux paths.  
         [0025]     The description above only illustrates specific embodiments and examples of the invention. The invention should therefore cover various modifications and variations made to the herein-described structure and operations of the invention, provided they fall within the scope of the invention as defined in the following appended claims.