Abstract:
A transformer for cathode tube inverter in accordance with claim  1  is capable of driving a plurality of light tubes while also balancing light intensity of each light tube, thereby offering better efficiencies and reducing production cost of related circuits thereof.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    (a) Field of the Invention  
           [0002]    The invention relates to a transformer for cathode tube inverter, and more particularly, to a twin-like U-shaped or a triplet-like transformer, wherein a primary coil thereof is shared, the primary coil and other secondary coils thereof are completed isolated with respect to electric circuits, and the secondary coils are completely or mostly as well as mutually isolated with respect to electric circuits. By having magnetic circuits completely or mostly as well as mutually isolated, miscellaneous complications resulted from an inverter simultaneously driving two or more light tubes are minimized.  
           [0003]    (b) Description of the Prior Art  
           [0004]    To have a conventional inverter of a cathode tube simultaneously drive two or more light tubes, two sets of or more circuits and two or more transformers are needed. Referring to FIG. 1, when driving two or more light tubes, light intensity is not evenly distributed in case of two light tubes in parallel, meaning that currents in the light tubes are unbalanced. As a result, in order to maintain a balance of currents, more electronic components are required, and thus increasing production cost. For light tubes arranged in series, a high output voltage of the transformer from multiplying by the number of the light tubes is required. It is not entirely safe to use such devices, and expenses of related components are similarly increased.  
           [0005]    Accompanied with rapid advancement of display technologies, liquid-crystal-display (LCD) monitors are gradually replacing conventional cathode-ray-tube (CRT) monitors for being smaller in thickness, occupying relatively smaller spaces, and having stable definition without flickering. An interior of an LCD monitor is provided with a backlight module, which contains a high-voltage driven cathode tube serving as a light source in a backlight system thereof. This type of light tube is generally driven by an inverter, and has a high-voltage transformer apart from driving circuits. Furthermore, sizes of LCD monitors are currently becoming larger and larger, and some even replace televisions we use at the present time. However, the prior inverter is designed to make a single transformer drive one light tube only, and hence the aforesaid complications are incurred when driving two or more light tubes.  
         SUMMARY OF THE INVENTION  
         [0006]    The object of the invention is to provide a twin-like U-shaped or a triplet-like transformer, wherein a middle coil thereof serves as a primary coil for input, and coils at two sides thereof serve as secondary coils for output. A driving circuit therein may be simplified owing to the primary coil shared, and complications caused by requirements of light tubes connected in series or parallel are also eliminated. In addition, by sharing the primary coil, the primary coil and the secondary coils are situated in a same iron core assembly with resultingly same output parameters as well, thereby smoothing away issues of light intensity differences of light tubes. It is also unquestionable that a number of transformers used is reduced for that a single transformer is capable of driving a multiple of light tubes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 shows a conventional exploded elevational schematic view of a prior transformer used in an inverter.  
         [0008]    [0008]FIG. 2 shows an exploded elevational schematic view of a transformer for inverter according to the invention.  
         [0009]    [0009]FIG. 3 shows a schematic view of an embodiment according to the invention.  
         [0010]    [0010]FIG. 4 shows another schematic view of an embodiment according to the invention.  
         [0011]    FIGS.  5  to  11  are elevational views illustrating structures of core assemblies according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    To better understand the invention, detailed descriptions shall be given with the accompanying drawings hereunder.  
         [0013]    Referring to FIG. 2, the transformer in accordance with the invention comprises three wire racks  1 ,  2  and  3 , and four U-shaped iron cores  4 ,  5 ,  6  and  7  as shown in FIG. 2A; or three wire racks  1 ,  2  and  3 , and two deformed E-shaped iron cores  8  as shown in FIG. 2B. Wherein, peripherals close to centers of the three wire racks  1 ,  2  and  3  are disposed with wire winding portions  11 ,  21  and  31  having a plurality of intervals. The wire winding portions  11 ,  21  and  31  are winded with coils and are hollow structures, and hollow portions  12 ,  22  and  32  thereof are for accommodating the iron cores  4 ,  5 ,  6  and  7  (or the iron cores  8 ). The wire racks  1 ,  2  and  3  are further provided and joined with a plurality of terminals  13 ,  23  and  33  connected with the coils, respectively.  
         [0014]    The aforesaid transformer is a twin-like U-shaped or a deformed dual E-shaped transformer, wherein the coil at the middle wire rack  1  is a primary coil serving as input, whereas as the coils at the two side wire racks  2  and  3  are secondary coils serving as output. The primary coil is shared within the iron cores  4 ,  5 ,  6  and  7  (or the iron cores  8 ) having same properties, and therefore the primary coil is completely isolated with other secondary coils with respect to electric circuits. By completely isolating the secondary coils with respect to electric circuits, and by completely or mostly as well as mutually isolating the secondary coils with respect to magnetic circuits, complications caused by requirements for driving two or more light tubes are eliminated.  
         [0015]    Referring to FIG. 3, in accordance with the invention, the middle wire rack  1  may be disposed with two sets of wire racks  2 ′ and  3 ′ at two sides thereof, respectively, and thus adding up to four wire racks in total.  
         [0016]    Referring to FIG. 4, in accordance with the invention, the middle wire rack  1  may be disposed with three (or more) sets of wire racks  2 ′ and  3 ′ at two sides thereof, respectively, and thus adding up to six (or more) wire racks in total.  
         [0017]    Referring to FIG. 5, the iron cores  8  may be a combination of two E-shaped iron cores  81  and  82 , and thus making up four deformed U-shaped iron cores.  
         [0018]    The following structures of iron cores are applicable to the invention. The characteristics thereof are that the primary coil therein is shared, and is completely isolated from other secondary coils with respect to electric circuits. In addition, the secondary coils are completely or mostly as well as mutually isolated with respect to magnetic circuits.  
         [0019]    Referring to FIG. 6, the iron cores  8  may be a combination of two E-shaped iron cores  91  and  92 .  
         [0020]    Referring to  7 , an iron core assembly  10  may be a combination of a U-shaped iron core  101  and a T-shaped iron core  102 .  
         [0021]    Referring to FIG. 8, an iron core assembly  11  may be a combination of an E-shaped iron core  111  and an I-shaped iron core  112 .  
         [0022]    Referring to FIG. 9, an iron core assembly  12  may be a combination of an F-shaped iron core  121  and an L-shaped iron core  122 .  
         [0023]    Referring to FIG. 10, an iron core assembly  13  may be a combination of two L-shaped iron cores  131  and  132 , and an I-shaped iron core  133 .  
         [0024]    Referring to FIG. 11, an iron core assembly  14  may be a combination of two U-shaped iron cores  141  and  142 , and an I-shaped iron core  143 .  
         [0025]    Conclusive from the above, the invention utilizes a transformer operating in coordination with combinations of side wire racks in multiples of two (two, four, six, eight and so on), and therefore the invention is capable of driving light tubes of equal quantity to the wire racks. Furthermore, light intensity of each of the light tubes is the same for that the wire racks are situated in a same iron core assembly.  
         [0026]    It is of course to be understood that the embodiments described herein are merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.