Patent Publication Number: US-7723996-B2

Title: Inverter circuit and backlight assembly having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application relies for priority upon Korean Patent Application No. 2006-94924 filed on Sep. 28, 2006, the disclosure of which is incorporated herein by reference. 
   BACKGROUND 
   1. Field of Invention 
   The present invention relates to liquid crystal displays and, more particularly, to a backlight assembly having an inverter for powering a plurality of discharge tubes, such as cold cathode fluorescent lamps, as a light source for the display. 
   2. Description of the Related Art 
   Conventional liquid crystal displays (LCDs) are made to be light-weight, compact and have low power consumption. Since the LCD is a non-emissive device, a light source such as cold cathode fluorescent lamp is used. The cold cathode fluorescent lamp is a kind of a fluorescent lamp that operates in the regular glow discharge region using an applied AC voltage. Since the cold cathode fluorescent lamp is not preheated by a filament, it is relatively more vibration resistant, has a thinner diameter and a longer life span compared to a hot cathode fluorescent lamp but requires a higher voltage to be applied, for which an inverter circuit is used. 
   As shown in  FIG. 18 , the conventional inverter circuit includes first and second inverters  11  and  12 , a plurality of balance transformers  13 , and a plurality of diodes  14 . 
   Primary coils  13   a  of the balance transformers  13  are connected to output terminals of the first and second inverters  11  and  12 . The first and second inverters  11  and  12  convert DC voltage into AC voltage and supply the AC voltage to two pairs of cold cathode fluorescent lamps  20  through the primary coils  13   a  of the balance transformers  13 . 
   Among the secondary coils  13   b  of the balance transformers  13 , adjacent secondary coils  13   b  are serially connected to each other to form a secondary coil serial loop, one end of the secondary coil serial loop being connected to the ground GND. 
   First ends of third coils  13   c  of the balance transformers  13  are connected to the ground GND through the secondary coil serial loop and second ends of the third coils  13   c  of the balance transformers  13  are connected to input terminals of the diodes  14 . 
   Input terminals of the diodes  14  are connected to the first ends of the third coils  13   c . The diodes  14  detect voltage generated from the third coils  13   c  and then generate voltage detection values. 
   Japanese Patent Unexamined Publication No. 2005-267923 discloses an error detection circuit employed in a discharge tube control circuit that controls the turn on/off of the first and second discharge tubes. An error signal generating device generates an error signal when the current balance of the first and second discharge tubes is different from the reference current balance. 
   However, as shown in  FIG. 19 , since the cold cathode fluorescent lamps are aligned between a diffusion plate and a reflective plate, when the cold cathode fluorescent lamps are turned on, heat is transferred upward by convection along the cold cathode fluorescent lamps causing the internal temperature of the backlight assembly to rise and lowering the lamps&#39; impedance.  FIG. 20  shows that, as the cold cathode fluorescent lamps generate heat, an impedance gradient occurs in the backlight assembly caused by the temperature gradient. 
   The conventional inverter circuit includes a circuit that detects voltage at the diodes connected to the third coils when the impedance changes due to the temperature gradient. The voltage value due to the impedance change must be taken into consideration when setting the threshold value used to detect the normal operation and abnormal operation. As a result, the conventional inverter circuit has a higher threshold value because of the increase of the voltage value caused by the impedance change according to the temperature gradient. For this reason, when the voltage is slightly increased due to arc discharge caused by an opening fault, the voltage level may not reach the threshold value, so that the voltage variation with temperature cannot be precisely detected. 
   SUMMARY 
   According to one aspect of the present invention, an inverter circuit precisely detects abnormal operation when the threshold voltage is increased due to the impedance change caused by the temperature gradient. 
   The present invention also provides a backlight assembly having the inverter circuit. 
   In one illustrative embodiment, an inverter circuit includes a plurality of balance transformers and a fault detection device that detects a fault based on the values of current applied to the balance transformers. The balance transformers include plural pairs of primary coils connected between the output terminals of inverters and plural pairs of discharge tubes and a plurality of secondary coils aligned corresponding to the primary coils, in which adjacent secondary coils are serially connected to each other to form a serial loop of the secondary coils, a part of the serial loop of the secondary coils being connected to ground. The fault detection device includes plural pairs of third coils aligned corresponding to the primary coils, in which adjacent third coils, which are aligned as a pair, are serially connected to each other to offset AC voltage generated from the paired third coils, one end of the paired third coils being connected to ground, a plurality of diodes having input terminals connected to the other end of the paired third coils so as to generate a voltage detection value by detecting voltage generated from the paired third coils, and a fault detector comparing the voltage detection value generated from output terminals of the diodes with a predetermined threshold value to detect a fault and generating the comparison result. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a circuit diagram showing an inverter circuit and a backlight assembly according to a first embodiment of the present invention; 
       FIG. 2  is a block diagram showing the structure of an inverter and a fault detection unit of a backlight assembly according to a first embodiment of the present invention; 
       FIG. 3  is a circuit diagram showing an inverter circuit and a backlight assembly according to a second embodiment of the present invention; 
       FIG. 4  is a circuit diagram showing an inverter circuit and a backlight assembly according to a third embodiment of the present invention; 
       FIG. 5  is a circuit diagram showing an inverter circuit and a backlight assembly according to a fourth embodiment of the present invention; 
       FIG. 6  is a circuit diagram showing an inverter circuit and a backlight assembly according to a fifth embodiment of the present invention; 
       FIG. 7  is a circuit diagram showing an inverter circuit and a backlight assembly according to a sixth embodiment of the present invention; 
       FIG. 8  is a circuit diagram showing an inverter circuit and a backlight assembly according to a seventh embodiment of the present invention; 
       FIG. 9  is a circuit diagram showing an inverter circuit and a backlight assembly according to an eighth embodiment of the present invention; 
       FIG. 10  is a circuit diagram showing an inverter circuit and a backlight assembly according to a ninth embodiment of the present invention; 
       FIG. 11  is a circuit diagram showing an inverter circuit and a backlight assembly according to a tenth embodiment of the present invention; 
       FIG. 12  is a circuit diagram showing an inverter circuit and a backlight assembly according to an eleventh embodiment of the present invention; 
       FIG. 13  is a circuit diagram showing an inverter circuit and a backlight assembly according to a twelfth embodiment of the present invention; 
       FIG. 14  is a circuit diagram showing an inverter circuit and a backlight assembly according to a thirteenth embodiment of the present invention; 
       FIG. 15  is a circuit diagram showing an inverter circuit and a backlight assembly according to a fourteenth embodiment of the present invention; 
       FIG. 16  is a circuit diagram showing an inverter circuit and a backlight assembly according to a fifteenth embodiment of the present invention; 
       FIG. 17  is a circuit diagram showing an inverter circuit and a backlight assembly according to a sixteenth embodiment of the present invention; 
       FIG. 18  is a circuit diagram showing a conventional inverter circuit; 
       FIG. 19  is a perspective view showing impedance variation according to temperature variation in a backlight assembly; and 
       FIG. 20  is a graph showing impedance variation according to temperature variation in a backlight assembly. 
   

   DETAILED DESCRIPTION 
   Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings. However, the scope of the present invention is not limited to such embodiments and the present invention may be realized in various forms. 
   Embodiment 1 
     FIG. 1  is a circuit diagram showing an inverter circuit and a backlight assembly according to a first embodiment of the present invention. 
   As shown in  FIG. 1 , the backlight assembly  100  includes the inverter circuit  110  and two pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  110  includes two inverters  111  and  112 , four balance transformers  113  to  116 , and a fault detection device  117 . 
   The inverter  111  converts DC voltage into AC voltage so as to apply the AC voltage (hereinafter, referred to as positive AC voltage for the purpose of discrimination relative to AC voltage to be described below) to the two pairs of the cold cathode fluorescent lamps  130  through primary coils  113   a  and  115   a  of the balance transformers  113  and  115 . The inverter  112  converts DC voltage into AC voltage so as to apply the AC voltage (hereinafter, referred to as negative AC voltage) having the same amplitude but opposite phase to the two pairs of the cold cathode fluorescent lamps  130  through primary coils  114   a  and  116   a  of the balance transformers  114  and  116 . 
   The balance transformer  113  has the primary coil  113   a  connected between an output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . The balance transformer  114  has the primary coil  114   a  connected between an output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . The balance transformer  115  has the primary coil  115   a  connected between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . The balance transformer  116  has the primary coil  116   a  connected between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . 
   AC voltage is induced in the secondary coils  113   b  and  114   b  and third coils  113   c  and  114   c  by the AC voltage applied to the primary coils  113   a  and  114   a . In addition, AC voltage is induced into the secondary coils  115   b  and  116   b  and third coils  115   c  and  116   c  by the AC voltage applied to the primary coils  115   a  and  116   a.    
   Other ends of the two pairs of the cold cathode fluorescent lamps  130  are connected to ground GND. The cold cathode fluorescent lamps  130  are driven by high voltage that causes high electrostatic noise to be generated by the cold cathode fluorescent lamps  130 . To reduce the effect of this high electrostatic noise, voltages that have a phase difference of 180° are preferably applied to the cold cathode fluorescent lamps  130 . According to the first embodiment as shown in  FIG. 1 , positive and negative high AC voltages, which are phase-shifted from each other by 180°, are applied to adjacent cold cathode fluorescent lamps  130 , so that electrostatic noise generated from the cold cathode fluorescent lamps  130  is offset. 
   Among the secondary coils  113   b ,  114   b ,  115   b  and  116   b  of four balance transformers  113 ,  114 ,  115  and  116 , adjacent secondary coils are serially connected to each other to form a serial loop, a part of the secondary coil serial loop being connected to the ground GND. The secondary coils  113   b ,  114   b ,  115   b  and  116   b  of four balance transformers  113 ,  114 ,  115  and  116  generate voltage detection values of the AC voltage induced by the primary coils  113   a ,  114   a ,  115   a , and  116   a  and transmit the voltage detection values to a fault detector  120 . 
   The fault detection device  117  detects high voltage abnormal discharge in the inverter circuit  110 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and ground GND. The fault detection device  117  detects the abnormal operation based on the voltage detection values generated from voltages of the balance transformers  113 ,  114 ,  115  and  116 . 
   The fault detection device  117  includes two pairs of third coils  113   c ,  114   c ,  115   c  and  116   c  added to four balance transformers  113 ,  114 ,  115  and  116 , two diodes  118  and  119 , the fault detector  120  and an indicator  121 . 
   Among the third coils  113   c ,  114   c ,  115   c  and  116   c , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, one end of the paired third coils being connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  113   c  and  114   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  113   c  and  114   c , one end of the paired third coils  113   c  and  114   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b  and  116   b.    
   In addition, the paired third coils  115   c  and  116   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  115   c  and  116   c , one end of the paired third coils  115   c  and  116   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b  and  116   b.    
   Input terminals of the diodes  118  and  119  are connected to the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  118  is connected to the paired third coils  113   c  and  114   c  adjacent to each other in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  113   c  and  114   c.    
   In addition, the input terminal of the diode  119  is connected to the paired third coils  115   c  and  116   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  115   c  and  116   c.    
   The fault detector  120  is connected to output terminals of the diodes  118  and  119 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  118  and  119  with the predetermined threshold value so as to detect the fault and generates the comparison result. 
   The indicator  121 , for instance, displays the comparison result on a display device (not shown). 
   Hereinafter, an example of the fault detector  120  will be described with reference to  FIG. 2 .  FIG. 2  is a block diagram showing an example of the fault detector  120 . 
   As shown in  FIG. 2 , the fault detector  120  includes a ripple DC voltage converter  1201 , a reference voltage generator  1202 , and a comparator  1203 . 
   An input terminal of the ripple DC voltage converter  1201  is connected to the output terminals of the diodes  118  and  119 . An output terminal of the ripple DC voltage converter  1201  is connected to one input terminal of the comparator  1203 . An output terminal of the reference voltage generator  1202  is connected to the other input terminal of the comparator  1203 . An output terminal of the comparator  1203  is connected to an input terminal of the indicator  121 . 
   The ripple DC voltage converter  1201  converts ripple voltage detected from the diodes  118  and  119  into DC voltage through filtering or peak hold scheme and sends a voltage detection value to the comparator  1203 . The reference voltage generator  1202  generates reference voltage and sends the reference voltage to the comparator  1203 . The comparator  1203  compares the voltage detection value output from the ripple DC voltage converter  1201  with the reference voltage value output from the reference voltage generator  1202 , and sends the comparison result to the indicator  121 . The indicator  121  displays the comparison result obtained from the comparator  1203 . 
   According to the first embodiment of the present invention, the adjacent third coils, which are aligned as a pair, are serially connected to each other so that the AC voltages generated from the paired third coils are offset. In addition, one end of the paired third coils is connected to the input terminals of the diodes. Further, the fault detector  120  compares the voltage detection value generated from voltage of the diodes with the predetermined threshold value so as to detect the fault and sends the comparison result to the indicator  121 . Thus, according to the first embodiment of the present invention, the threshold value used to detect the abnormal operation of the backlight assembly can be appropriately set and the abnormal operation can be precisely detected, even if the voltage rises in the backlight assembly  100  due to impedance variation caused by the temperature gradient. 
   That is, according to the first embodiment of the present invention, when impedance variation occurs due to the temperature gradient in the plural cold cathode fluorescent lamps  130 , each paired third coils may generate voltages different from each other due to the difference in impedance, but AC voltages generated from the paired third coils, which are adjacent to each other, are offset from each other, so the threshold value can be set based on the differential voltage between the paired third coils. Thus, as compared with the conventional art, abnormal operation of the backlight assembly can be precisely detected even if the threshold value is set to a low level. Therefore, since the first embodiment of the present invention can appropriately set the threshold value, voltage variation can be precisely detected even if the voltage is slightly increased due to arc discharge caused by an opening fault and is below the threshold value under a condition of the conventional art. Thus, abnormal operation of the backlight assembly can be precisely detected. 
   In addition, according to the first embodiment of the present invention, only one diode is required for the paired third coils, which are adjacent to each other, so the number of diodes can be reduced as compared with the prior art in which a diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   Embodiment 2 
   Hereinafter, a second embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 3  is a circuit diagram showing an inverter circuit and a backlight assembly according to the second embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the first embodiment, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 3 , the backlight assembly  200  according to the second embodiment of the present invention includes the inverter circuit  210  and four pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  210  includes two inverters  111  and  112 , eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 , and a fault detection device  215 . That is, the inverter circuit  210  according to the second embodiment of the present invention further includes balance transformers  211 ,  212 ,  213  and  214  as compared with the inverter circuit  110  according to the first embodiment of the present invention, and the fault detection device  215  is provided instead of the fault detection device  117 . The inverter  111  converts DC voltage into AC voltage so as to apply positive AC voltage to the four pairs of the cold cathode fluorescent lamps  130  through primary coils  113   a ,  115   a ,  211   a  and  213   a  of the balance transformers  113 ,  115 ,  211  and  213 . The inverter  112  converts DC voltage into AC voltage so as to apply negative AC voltage, which has amplitude identical to that of the positive AC voltage and the phase thereof is shifted by 180° as compared with that of the positive AC voltage, to the four pairs of the cold cathode fluorescent lamps  130  through primary coils  114   a ,  116   a ,  212   a  and  214   a  of the balance transformers  114 ,  116 ,  212  and  214 . 
   The balance transformer  211  has the primary coil  211   a  connected to the inverter  111  in parallel to the balance transformers  113  and  115  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . In addition, the balance transformer  212  has the primary coil  212   a  connected to the inverter  112  in parallel to the balance transformers  114  and  116  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . Further, the balance transformer  213  has the primary coil  213   a  connected to the inverter  111  in parallel to the balance transformers  113  and  115  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . The balance transformer  214  has the primary coil  214   a  connected to the inverter  112  in parallel to the balance transformers  114  and  116  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . 
   AC voltage is induced to the secondary coils  211   b  and  212   b  and third coils  211   c  and  212   c  by AC voltage applied to the primary coils  211   a  and  212   a . In addition, AC voltage is induced to the secondary coils  213   b  and  214   b  and third coils  213   c  and  214   c  by AC voltage applied to the primary coils  213   a  and  214   a.    
   Among the secondary coils  211   b ,  212   b ,  213   b  and  214   b  of the four balance transformers  211 ,  212 ,  213  and  214 , adjacent coils are serially connected to each other to form a serial loop, and a part of the secondary coil serial loop is connected to the ground GND. The secondary coils  211   b ,  212   b ,  213   b  and  214   b  of four balance transformers  211 ,  212 ,  213  and  214  generate voltage detection values of the AC voltage induced by the primary coils  211   a ,  212   a ,  213   a , and  214   a  and transmit the voltage detection values to a fault detector  120 . 
   The fault detection device  215  detects high voltage abnormal discharge in the inverter circuit  210 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  215  detects the abnormal operation based on the voltage detection values generated from voltages of the eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 . 
   The fault detection device  215  includes four pairs of third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c ,  212   c ,  213   c  and  214   c  added to the eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 , four diodes  118 ,  119 ,  216  and  217 , the fault detector  120  and an indicator  121 . That is, the fault detection device  215  according to the second embodiment of the present invention further includes two pairs of third coils  211   c ,  212   c ,  213   c  and  214   c  and two diodes  216  and  217  as compared with the fault detection device  117  according to the first embodiment of the present invention. 
   Among the third coils  211   c ,  212   c ,  213   c  and  214   c , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  211   c  and  212   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  211   c  and  212   c , one end of the paired third coils  211   c  and  212   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   In addition, the paired third coils  213   c  and  214   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  213   c  and  214   c , one end of the paired third coils  213   c  and  214   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   Input terminals of the diodes  216  and  217  are connected to the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. The voltage detection value is output from the ripple DC voltage converter  1201  of the fault detector  120 . 
   That is, the input terminal of the diode  216  is connected to the paired third coils  211   c  and  212   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  211   c  and  212   c.    
   In addition, the input terminal of the diode  217  is connected to the paired third coils  213   c  and  214   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  213   c  and  214   c.    
   Embodiment 3 
   Hereinafter, a third embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 4  is a circuit diagram showing an inverter circuit and a backlight assembly according to the third embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the second embodiment, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 4 , the backlight assembly  300  according to the third embodiment of the present invention includes the inverter circuit  310  and six pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  310  includes two inverters  111  and  112 , twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313  and  314 , and a fault detection device  315 . That is, the inverter circuit  310  according to the third embodiment of the present invention further includes balance transformers  311 ,  312 ,  313  and  314  as compared with the inverter circuit  210  according to the second embodiment of the present invention, and the fault detection device  315  is provided instead of the fault detection device  215 . 
   The inverter  111  converts DC voltage into AC voltage so as to apply positive AC voltage to the six pairs of the cold cathode fluorescent lamps  130  through primary coils  113   a ,  115   a ,  211   a ,  213   a ,  311   a  and  313   a  of the balance transformers  113 ,  115 ,  211 ,  213 ,  311  and  313 . The inverter  112  converts DC voltage into AC voltage so as to apply negative AC voltage, which has amplitude identical to that of the positive AC voltage and the phase thereof is shifted by 180° as compared with that of the positive AC voltage, to the six pairs of the cold cathode fluorescent lamps  130  through primary coils  114   a ,  116   a ,  212   a ,  214   a ,  312   a  and  314   a  of the balance transformers  114 ,  116 ,  212 ,  214 ,  312  and  314 . 
   The balance transformer  311  has the primary coil  311   a  connected to the inverter  111  in parallel to the balance transformers  113 ,  115 ,  211  and  213  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . In addition, the balance transformer  312  has the primary coil  312   a  connected to the inverter  112  in parallel to the balance transformers  114 ,  116 ,  212  and  214  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . Further, the balance transformer  313  has the primary coil  313   a  connected to the inverter  111  in parallel to the balance transformers  113 ,  115 ,  211  and  213  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . The balance transformer  314  has the primary coil  314   a  connected to the inverter  112  in parallel to the balance transformers  114 ,  116 ,  212  and  214  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . 
   AC voltage applied to the primary coils  311   a  and  312   a  is induced to the secondary coils  311   b  and  312   b  and third coils  311   c  and  312   c  by AC voltage applied to the primary coils  311   a  and  312   a . In addition, AC voltage is induced to the secondary coils  313   b  and  314   b  and third coils  313   c  and  314   c  by AC voltage applied to the primary coils  313   a  and  314   a.    
   Among the secondary coils  311   b ,  312   b ,  313   b  and  314   b  of the four balance transformers  311 ,  312 ,  313  and  314 , adjacent secondary coils are serially connected to each other to form a serial loop, and a part of the secondary coil serial loop is connected to the ground GND. The secondary coils  311   b ,  312   b ,  313   b  and  314   b  of four balance transformers  311 ,  312 ,  313  and  314  generate voltage detection values of the AC voltage induced by the primary coils  311   a ,  312   a ,  313   a , and  314   a  and transmit the voltage detection values to a fault detector  120 . 
   The fault detection device  315  detects high voltage abnormal discharge in the inverter circuit  310 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  315  detects the abnormal operation based on the voltage detection values generated from voltages of the twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313  and  314 . 
   The fault detection device  315  includes six pairs of third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c ,  212   c ,  213   c ,  214   c ,  311   c ,  312   c ,  313   c  and  314   c  added to the twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 , and  314 , six diodes  118 ,  119 ,  216 ,  217 ,  316  and  317 , the fault detector  120  and an indicator  121 . That is, the fault detection device  315  according to the third embodiment of the present invention further includes two pairs of third coils  311   c ,  312   c ,  313   c  and  314   c  and two diodes  316  and  317  as compared with the fault detection device  215  according to the second embodiment of the present invention. 
   Among the third coils  311   c ,  312   c ,  313   c  and  314   c , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  311   c  and  312   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  311   c  and  312   c , one end of the paired third coils  311   c  and  312   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  313   c  and  314   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  313   c  and  314   c , one end of the paired third coils  313   c  and  314   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Input terminals of the diodes  316  and  317  are connected to the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. The voltage detection value is output from the ripple DC voltage converter  1201  of the fault detector  120 . 
   That is, the input terminal of the diode  316  is connected to the paired third coils  311   c  and  312   c  adjacent to each other in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  311   c  and  312   c.    
   In addition, the input terminal of the diode  317  is connected to the paired third coils  313   c  and  314   c  adjacent to each other in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  313   c  and  314   c.    
   Embodiment 4 
   Hereinafter, a fourth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 5  is a circuit diagram showing an inverter circuit and a backlight assembly according to the fourth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the third embodiment, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 5 , the backlight assembly  400  according to the fourth embodiment of the present invention includes the inverter circuit  410  and eight pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  410  includes two inverters  111  and  112 , sixteen balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413  and  414 , and a fault detection device  415 . That is, the inverter circuit  410  according to the fourth embodiment of the present invention further includes balance transformers  411 ,  412 ,  413  and  414  as compared with the inverter circuit  310  according to the third embodiment of the present invention, and the fault detection device  415  is provided instead of the fault detection device  315 . 
   The inverter  111  converts DC voltage into AC voltage so as to apply positive AC voltage to the eight pairs of the cold cathode fluorescent lamps  130  through primary coils  113   a ,  115   a ,  211   a ,  213   a ,  311   a ,  313   a ,  411   a  and  413   a  of the balance transformers  113 ,  115 ,  211 ,  213 ,  311 ,  313 ,  411  and  413 . The inverter  112  converts DC voltage into AC voltage so as to apply negative AC voltage, which has amplitude identical to that of the positive AC voltage and the phase thereof is shifted by 180° as compared with that of the positive AC voltage, to the eight pairs of the cold cathode fluorescent lamps  130  through primary coils  114   a ,  116   a ,  212   a ,  214   a ,  312   a ,  314   a ,  412   a  and  414   a  of the balance transformers  114 ,  116 ,  212 ,  214 ,  312 ,  314 ,  412  and  414 . 
   The balance transformer  411  has the primary coil  411   a  connected to the inverter  111  in parallel to the balance transformers  113 ,  115 ,  211 ,  213 ,  311  and  313  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . In addition, the balance transformer  412  has the primary coil  412   a  connected to the inverter  112  in parallel to the balance transformers  114 ,  116 ,  212 ,  214 ,  312  and  314  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . Further, the balance transformer  413  has the primary coil  413   a  connected to the inverter  111  in parallel to the balance transformers  113 ,  115 ,  211 ,  213 ,  311  and  313  and disposed between the output terminal of the inverter  111  and the cold cathode fluorescent lamp  130 . The balance transformer  414  has the primary coil  414   a  connected to the inverter  112  in parallel to the balance transformers  114 ,  116 ,  212 ,  214 ,  312  and  314  and disposed between the output terminal of the inverter  112  and the cold cathode fluorescent lamp  130 . 
   AC voltage is induced to the secondary coils  411   b  and  412   b  and third coils  411   c  and  412   c  by AC voltage applied to the primary coils  411   a  and  412   a . In addition, AC voltage is induced to the secondary coils  413   b  and  414   b  and third coils  413   c  and  414   c  by AC voltage applied to the primary coils  413   a  and  414   a.    
   Among the secondary coils  411   b ,  412   b ,  413   b  and  414   b  of the four balance transformers  411 ,  412 ,  413  and  414 , adjacent secondary coils are serially connected to each other to form a serial loop, and a part of the secondary coil serial loop is connected to the ground GND. The secondary coils  411   b ,  412   b ,  413   b  and  414   b  of four balance transformers  411 ,  412 ,  413  and  414  generate voltage detection values of the AC voltage induced by the primary coils  411   a ,  412   a ,  413   a , and  414   a  and transmit the voltage detection values to a fault detector  120 . 
   The fault detection device  415  detects high voltage abnormal discharge in the inverter circuit  410 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  415  detects the abnormal operation based on the voltage detection values generated from voltages of the sixteen balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413  and  414 . 
   The fault detection device  415  includes eight pairs of third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c ,  212   c ,  213   c ,  214   c ,  311   c ,  312   c ,  313   c ,  314   c ,  411   c ,  412   c ,  413   c  and  414   c  added to the sixteen balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413 , and  414 , eight diodes  118 ,  119 ,  216 ,  217 ,  316 ,  317 ,  416  and  417 , the fault detector  120  and an indicator  121 . That is, the fault detection device  415  according to the fourth embodiment of the present invention further includes two pairs of third coils  411   c ,  412   c ,  413   c  and  414   c  and two diodes  416  and  417  as compared with the fault detection device  315  according to the third embodiment of the present invention. 
   Among the third coils  411   c ,  412   c ,  413   c  and  414   c , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  411   c  and  412   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  411   c  and  412   c , and one end of the paired third coils  411   c  and  412   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In addition, the paired third coils  413   c  and  414   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  413   c  and  414   c , and one end of the paired third coils  413   c  and  414   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Input terminals of the diodes  416  and  417  are connected to the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. The voltage detection value is output from the ripple DC voltage converter  1201  of the fault detector  120 . 
   That is, the input terminal of the diode  416  is connected to the paired third coils  411   c  and  412   c  adjacent to each other in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  411   c  and  412   c.    
   In addition, the input terminal of the diode  417  is connected to the paired third coils  413   c  and  414   c  adjacent to each other in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  413   c  and  414   c.    
   Embodiment 5 
   Hereinafter, a fifth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 6  is a circuit diagram showing an inverter circuit and a backlight assembly according to the fifth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the first embodiment, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 6 , the backlight assembly  500  according to the fifth embodiment of the present invention includes the inverter circuit  110 , two pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and two lamp connectors  510  and  511 . That is, the backlight assembly  500  according to the fifth embodiment of the present invention further includes the lamp connectors  510  and  511  as compared with the backlight assembly  100  according to the first embodiment of the present invention. 
   The lamp connectors  510  and  511  combine adjacent cold cathode fluorescent lamps  130  with each other, respectively. In addition, the lamp connectors  510  and  511  connect the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  113   a ,  114   a ,  115   a  and  116   a  of the balance transformers  113 ,  114 ,  115  and  116 , respectively. 
   That is, the lamp connector  510  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  113   a  and  114   a  of the balance transformers  113  and  114 , respectively. 
   In addition, the lamp connector  511  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  115   a  and  116   a  of the balance transformers  115  and  116 , respectively. 
   According to the fifth embodiment of the present invention, when plural pairs of cold cathode fluorescent lamps are connected to the balance transformers, two cold cathode fluorescent lamps are combined by means of the connector, so that the fifth embodiment is more efficient than the first embodiment. Further, workability can be improved when installing or exchanging the cold cathode fluorescent lamps, so the manufacturing cost can be reduced. 
   Embodiment 6 
   Hereinafter, a sixth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 7  is a circuit diagram showing an inverter circuit and a backlight assembly according to the sixth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the second and fifth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 7 , the backlight assembly  600  according to the sixth embodiment of the present invention includes the inverter circuit  210 , four pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and four lamp connectors  510 ,  511 ,  610  and  611 . That is, the backlight assembly  600  according to the sixth embodiment of the present invention further includes the lamp connectors  610  and  611  as compared with the backlight assemblies  200  and  500  according to the second and fifth embodiments of the present invention. 
   The lamp connectors  610  and  611  combine two pairs of adjacent cold cathode fluorescent lamps  130  with each other among a plurality of cold cathode fluorescent lamps  130 . In addition, the lamp connectors  610  and  611  connect the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  211   a ,  212   a ,  213   a  and  214   a  of the four balance transformers  211 ,  212 ,  213  and  214 , respectively. 
   That is, the lamp connector  610  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  211   a  and  212   a  of the balance transformers  211  and  212 , respectively. 
   In addition, the lamp connector  611  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  213   a  and  214   a  of the balance transformers  213  and  214 , respectively. 
   Embodiment 7 
   Hereinafter, a seventh embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 8  is a circuit diagram showing an inverter circuit and a backlight assembly according to the seventh embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the third and sixth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 8 , the backlight assembly  700  according to the seventh embodiment of the present invention includes the inverter circuit  310 , six pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and six lamp connectors  510 ,  511 ,  610 ,  611 ,  710  and  711 . That is, the backlight assembly  700  according to the seventh embodiment of the present invention further includes the lamp connectors  710  and  711  as compared with the backlight assemblies  300  and  600  according to the third and sixth embodiments of the present invention. 
   The lamp connectors  710  and  711  combine two pairs of adjacent cold cathode fluorescent lamps  130  with each other among a plurality of cold cathode fluorescent lamps  130 . In addition, the lamp connectors  710  and  711  connect the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  311   a ,  312   a ,  313   a  and  314   a  of the four balance transformers  311 ,  312 ,  313  and  314 , respectively. 
   That is, the lamp connector  710  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  311   a  and  312   a  of the balance transformers  311  and  312 , respectively. 
   In addition, the lamp connector  711  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  313   a  and  314   a  of the balance transformers  313  and  314 , respectively. 
   Embodiment 8 
   Hereinafter, an eighth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 9  is a circuit diagram showing an inverter circuit and a backlight assembly according to the eighth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the fourth and sixth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 9 , the backlight assembly  800  according to the eighth embodiment of the present invention includes the inverter circuit  410 , eight pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and eight lamp connectors  510 ,  511 ,  610 ,  611 ,  710 ,  711 ,  810  and  811 . That is, the backlight assembly  800  according to the eighth embodiment of the present invention further includes the lamp connectors  810  and  811  as compared with the backlight assemblies  400  and  700  according to the fourth and seventh embodiments of the present invention. 
   The lamp connectors  810  and  811  combine two pairs of adjacent cold cathode fluorescent lamps  130  with each other among a plurality of cold cathode fluorescent lamps  130 . In addition, the lamp connectors  810  and  811  connect the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  411   a ,  412   a ,  413   a  and  414   a  of the four balance transformers  411 ,  412 ,  413  and  414 , respectively. 
   That is, the lamp connector  810  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  411   a  and  412   a  of the balance transformers  411  and  412 , respectively. 
   In addition, the lamp connector  811  connects a pair of the cold cathode fluorescent lamps  130  to the inverters  111  and  112  through primary coils  413   a  and  414   a  of the balance transformers  413  and  414 , respectively. 
   Embodiment 9 
   Hereinafter, a ninth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 10  is a circuit diagram showing an inverter circuit and a backlight assembly according to the ninth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the first and fifth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 10 , the backlight assembly  900  according to the ninth embodiment of the present invention includes the inverter circuit  910 , two pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and two lamp connectors  510  and  511 . 
   The inverter circuit  910  includes two inverters  111  and  112 , four balance transformers  113 ,  114 ,  115  and  116 , and a fault detection device  911 . That is, the inverter circuit  910  according to the ninth embodiment of the present invention is identical to the inverter circuit  110  according to the first embodiment of the present invention, except for the structure of the fault detection device  911 . 
   The fault detection device  911  detects high voltage abnormal discharge in the inverter circuit  910 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  911  detects the abnormal operation based on the voltage detection values generated from voltages of the balance transformers  113 ,  114 ,  115  and  116 . 
   The fault detection device  911  includes third coils  912   c ,  913   c ,  914   c , and  915   c  added to balance transformers  113 ,  114 ,  115  and  116 , two diodes  916  and  917 , a fault detector  120  and an indicator  121 . 
   Among the third coils  912   c ,  913   c ,  914   c , and  915   c , paired third coils, to which AC voltage is induced from primary coils connected to different connectors, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  912   c  and  915   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  912   c  and  915   c , in which the AC voltage is induced to the paired third coils  912   c  and  915   c  from the primary coils  113   a  and  116   a  connected to different connectors  510  and  511 , respectively. One end of the paired third coils  912   c  and  915   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b  and  116   b.    
   In addition, the paired third coils  913   c  and  914   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  913   c  and  914   c , in which the AC voltage is induced to the paired third coils  913   c  and  914   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , respectively. One end of the paired third coils  913   c  and  914   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b  and  116   b.    
   Input terminals of the diodes  916  and  917  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  916  is connected to one end of the paired third coils  912   c  and  915   c , to which the AC voltage is induced from the primary coils  113   a  and  116   a  connected to different connectors  510  and  511 , respectively, in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  912   c  and  915   c.    
   In addition, the input terminal of the diode  917  is connected to one end of the paired third coils  913   c  and  914   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  913   c  and  914   c.    
   The fault detector  120  is connected to output terminals of the diodes  916  and  917 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  916  and  917  with the predetermined threshold value so as to detect the fault and generates the comparison result. The comparison result is output by the indicator  121 . 
   According to the ninth embodiment of the present invention, the paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so that the AC voltages generated from the paired third coils are offset. In addition, one end of the paired third coils is connected to the input terminals of the diodes. Further, the fault detector  120  compares the voltage detection value generated from voltage of the diodes with the predetermined threshold value so as to detect the fault and sends the comparison result to the indicator  121 . Thus, according to the ninth embodiment of the present invention, the threshold value used to detect the abnormal operation of the backlight assembly can be appropriately set and the abnormal operation can be precisely detected, even if the opening fault of the cold cathode fluorescent lamps occurs in the backlight assembly. 
   That is, according to the ninth embodiment of the present invention, even if the opening fault occurs in the connector that combines a pair of cold cathode fluorescent lamps with each other, since the third coil to which the AC voltage is induced from the primary coil connected between the connector and the output terminal of the inverter, is serially connected to another third coil to which the AC voltage is induced from the primary coil connected to the other connector, the AC voltage generated from the pair of third coils is offset from each other, so that the abnormal operation of the backlight assembly can be precisely detected. 
   In addition, according to the ninth embodiment of the present invention, only one diode is required for the paired third coils, so the number of diodes can be reduced as compared with the prior art in which the diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   Embodiment 10 
   Hereinafter, a tenth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 11  is a circuit diagram showing an inverter circuit and a backlight assembly according to the tenth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the second and sixth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 11 , the backlight assembly  1000  according to the tenth embodiment of the present invention includes the inverter circuit  1010 , four pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and four lamp connectors  510 ,  511 ,  610  and  611 . 
   The inverter circuit  1010  includes two inverters  111  and  112 , eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214  and a fault detection device  1011 . That is, the inverter circuit  1010  according to the tenth embodiment of the present invention is identical to the inverter circuit  210  according to the second embodiment of the present invention, except for the structure of the fault detection device  1011 . 
   The fault detection device  1011  detects high voltage abnormal discharge in the inverter circuit  1010 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1011  detects the abnormal operation based on the voltage detection values generated from voltages of the eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 . The fault detection device  1011  includes third coils  1012   c ,  1013   c ,  1014   c ,  1015   c ,  1016   c ,  1017   c ,  1018   c  and  1019   c  added to the eight balance transformers  1113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 , four diodes  1020 ,  1021 ,  1022 , and  1023 , a fault detector  120  and an indicator  121 . 
   Among the third coils  1012   c ,  1013   c ,  1014   c ,  1015   c ,  1016   c ,  1017   c ,  1018   c  and  1019   c , paired third coils to which AC voltage is induced from primary coils connected to different connectors are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1012   c  and  1019   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1012   c  and  1019   c , in which the AC voltage is induced to the paired third coils  1012   c  and  1019   c  from the primary coils  113   a  and  214   a  connected to different connectors  510  and  611 . One end of the paired third coils  1012   c  and  1019   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   In addition, the paired third coils  1013   c  and  1014   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1013   c  and  1014   c , in which the AC voltage is induced to the paired third coils  1013   c  and  1014   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 . One end of the paired third coils  1013   c  and  1014   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   Further, the paired third coils  1015   c  and  1016   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1015   c  and  1016   c , in which the AC voltage is induced to the paired third coils  1015   c  and  1016   c  from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 . One end of the paired third coils  1015   c  and  1016   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   Furthermore, the paired third coils  1017   c  and  1018   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1017   c  and  1018   c , in which the AC voltage is induced to the paired third coils  1017   c  and  1018   c  from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 . One end of the paired third coils  1017   c  and  1018   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b.    
   Input terminals of the diodes  1020 ,  1021 ,  1022  and  1023  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1020  is connected to one end of the paired third coils  1012   c  and  1019 , to which the AC voltage is induced from the primary coils  113   a  and  214   a  connected to different connectors  510  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1012   c  and  1019   c.    
   In addition, the input terminal of the diode  1021  is connected to one end of the paired third coils  1013   c  and  1014   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1013   c  and  1014   c.    
   Further, the input terminal of the diode  1022  is connected to one end of the paired third coils  1015   c  and  1016   c , to which the AC voltage is induced from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1015   c  and  1016   c.    
   Furthermore, the input terminal of the diode  1023  is connected to one end of the paired third coils  1017   c  and  1018   c , to which the AC voltage is induced from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1017   c  and  1018   c.    
   The fault detector  120  is connected to output terminals of the four diodes  1020 ,  1021 ,  1022  and  1023 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  1020 ,  1021 ,  1022  and  1023  with the predetermined threshold value so as to detect the fault and generates the comparison result. The comparison result is output by the indicator  121 . 
   Embodiment 11 
   Hereinafter, an eleventh embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 12  is a circuit diagram showing an inverter circuit and a backlight assembly according to the eleventh embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the third and seventh embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 12 , the backlight assembly  1100  according to the eleventh embodiment of the present invention includes the inverter circuit  1110 , six pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and six lamp connectors  510 ,  511 ,  610 ,  611 ,  710  and  711 . 
   The inverter circuit  1110  includes two inverters  111  and  112 , twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313  and  314  and a fault detection device  1111 . That is, the inverter circuit  1110  according to the eleventh embodiment of the present invention is identical to the inverter circuit  310  according to the third embodiment of the present invention, except for the structure of the fault detection device  1111 . 
   The fault detection device  1111  detects high voltage abnormal discharge in the inverter circuit  1110 , such as corona discharge and arc discharge that are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1111  detects the abnormal operation based on the voltage detection values generated from voltages of the twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313  and  314 . 
   The fault detection device  1111  includes third coils  1112   c ,  1113   c ,  1114   c ,  1115   c ,  1116   c ,  1117   c ,  1118   c ,  1119   c ,  1120   c ,  1121   c ,  1122   c  and  1123   c  added to the twelve balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313  and  314 , six diodes  1124 ,  1125 ,  1126 ,  1127 ,  1128  and  1129 , a fault detector  120  and an indicator  121 . Among the third coils  1112   c ,  1113   c ,  1114   c ,  1115   c ,  1116   c ,  1117   c ,  1118   c ,  1119   c ,  1120   c ,  1121   c ,  1122   c  and  1123   c , paired third coils to which AC voltage is induced from primary coils connected to different connectors are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, rather than being connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1112   c  and  1123   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1112   c  and  1123   c , in which the AC voltage is induced to the paired third coils  1112   c  and  1123   c  from the primary coils  113   a  and  314   a  connected to different connectors  510  and  711 . One end of the paired third coils  1112   c  and  1123   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  1113   c  and  1114   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1113   c  and  1114   c , in which the AC voltage is induced to the paired third coils  1113   c  and  1114   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 . One end of the paired third coils  1113   c  and  1114   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  1115   c  and  1116   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1115   c  and  1116   c , in which the AC voltage is induced to the paired third coils  1115   c  and  1116   c  from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 . One end of the paired third coils  1115   c  and  1116   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Furthermore, the paired third coils  1117   c  and  1118   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1117   c  and  1118   c , in which the AC voltage is induced to the paired third coils  1117   c  and  1118   c  from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 . One end of the paired third coils  1117   c  and  1118   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  1119   c  and  1120   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1119   c  and  1120   c , in which the AC voltage is induced to the paired third coils  1119   c  and  1120   c  from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 . One end of the paired third coils  1119   c  and  1120   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  1121   c  and  1122   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1121   c  and  1122   c , in which the AC voltage is induced to the paired third coils  1121   c  and  1122   c  from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 . One end of the paired third coils  1121   c  and  1122   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Input terminals of the diodes  1124 ,  1125 ,  1126 ,  1127 ,  1128  and  1129  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and so as to produce the voltage detection value. 
   That is, the input terminal of the diode  1124  is connected to one end of the paired third coils  1112   c  and  1123   c , to which the AC voltage is induced from the primary coils  113   a  and  314   a  connected to different connectors  510  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1112   c  and  1123   c.    
   In addition, the input terminal of the diode  1125  is connected to one end of the paired third coils  1113   c  and  1114   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1113   c  and  1114   c.    
   Further, the input terminal of the diode  1126  is connected to one end of the paired third coils  1115   c  and  1116   c , to which the AC voltage is induced from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1115   c  and  1116   c.    
   Furthermore, the input terminal of the diode  1127  is connected to one end of the paired third coils  1117   c  and  1118   c , to which the AC voltage is induced from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1117   c  and  1118   c.    
   The input terminal of the diode  1128  is connected to one end of the paired third coils  1119   c  and  1120   c , to which the AC voltage is induced from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1119   c  and  1120   c.    
   In addition, the input terminal of the diode  1129  is connected to one end of the paired third coils  1121   c  and  1122   c , to which the AC voltage is induced from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1121   c  and  1122   c.    
   The fault detector  120  is connected to output terminals of the six diodes  1124 ,  1125 ,  1126 ,  1127 ,  1128  and  1129 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  1124 ,  1125 ,  1126 ,  1127 ,  1128  and  1129  with the predetermined threshold value so as to detect the fault and generates the comparison result. The comparison result is output by the indicator  121 . 
   Embodiment 12 
   Hereinafter, a twelfth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 13  is a circuit diagram showing an inverter circuit and a backlight assembly according to the twelfth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the fourth and eighth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 13 , the backlight assembly  1100  according to the twelfth embodiment of the present invention includes the inverter circuit  1210 , eight pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and eight lamp connectors  510 ,  511 ,  610 ,  611 ,  710 ,  711 ,  810  and  811 . 
   The inverter circuit  1210  includes two inverters  111  and  112 , sixteen balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413  and  414 , and a fault detection device  1211 . That is, the inverter circuit  1210  according to the twelfth embodiment of the present invention is identical to the inverter circuit  410  according to the fourth embodiment of the present invention, except for the structure of the fault detection device  1211 . 
   The fault detection device  1211  detects high voltage abnormal discharge in the inverter circuit  1210 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1211  detects the abnormal operation based on the voltage detection values of voltages generated from the sixteen balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413 , and  414 . 
   The fault detection device  1211  includes third coils  1212   c ,  1213   c ,  1214   c ,  1215   c ,  1216   c ,  1217   c ,  1218   c ,  1219   c ,  1220   c ,  1221   c ,  1222   c ,  1223   c ,  1224   c ,  1225   c ,  1226   c  and  1227   c  added to the sixteen balance transformers  1113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213 ,  214 ,  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413  and  414 , eight diodes  1228 ,  1229 ,  1230 ,  1231 ,  1232 ,  1233 ,  1234  and  1235 , a fault detector  120  and an indicator  121 . 
   Among the third coils  1212   c ,  1213   c ,  1214   c ,  1215   c ,  1216   c ,  1217   c ,  1218   c ,  1219   c ,  1220   c ,  1221   c ,  1222   c ,  1223   c ,  1224   c ,  1225   c ,  1226   c  and  1227   c , paired third coils to which AC voltage is induced from primary coils connected to different connectors are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1212   c  and  1227   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1212   c  and  1227   c , in which the AC voltage is induced to the paired third coils  1212   c  and  1227   c  from the primary coils  113   a  and  414   a  connected to different connectors  510  and  811 . One end of the paired third coils  1212   c  and  1227   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1213   c  and  1214   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1213   c  and  1214   c , in which the AC voltage is induced to the paired third coils  1213   c  and  1214   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 . One end of the paired third coils  1213   c  and  1214   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1215   c  and  1216   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1215   c  and  1216   c , in which the AC voltage is induced to the paired third coils  1215   c  and  1216   c  from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 . One end of the paired third coils  1215   c  and  1216   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1217   c  and  1218   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1217   c  and  1218   c , in which the AC voltage is induced to the paired third coils  1217   c  and  1218   c  from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 . One end of the paired third coils  1217   c  and  1218   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1219   c  and  1220   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1219   c  and  1220   c , in which the AC voltage is induced to the paired third coils  1219   c  and  1220   c  from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 . One end of the paired third coils  1219   c  and  1220   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1221   c  and  1222   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1221   c  and  1222   c , in which the AC voltage is induced to the paired third coils  1221   c  and  1222   c  from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 . One end of the paired third coils  1221   c  and  1222   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1223   c  and  1224   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1223   c  and  1224   c , in which the AC voltage is induced to the paired third coils  1223   c  and  1224   c  from the primary coils  314   a  and  411   a  connected to different connectors  711  and  810 . One end of the paired third coils  1223   c  and  1224   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The paired third coils  1225   c  and  1226   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1225   c  and  1226   c , in which the AC voltage is induced to the paired third coils  1225   c  and  1226   c  from the primary coils  412   a  and  413   a  connected to different connectors  810  and  811 . One end of the paired third coils  1225   c  and  1226   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Input terminals of the diodes  1228 ,  1229 ,  1230 ,  1231 ,  1232 ,  1233 ,  1234  and  1235  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1228  is connected to one end of the paired third coils  1212   c  and  1227   c , to which the AC voltage is induced from the primary coils  113   a  and  414   a  connected to different connectors  510  and  811 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1212   c  and  1227   c.    
   The input terminal of the diode  1229  is connected to one end of the paired third coils  1213   c  and  1214   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1213   c  and  1214   c.    
   The input terminal of the diode  1230  is connected to one end of the paired third coils  1215   c  and  1216   c , to which the AC voltage is induced from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1215   c  and  1216   c.    
   The input terminal of the diode  1231  is connected to one end of the paired third coils  1217   c  and  1218   c , to which the AC voltage is induced from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1217   c  and  1218   c.    
   The input terminal of the diode  1232  is connected to one end of the paired third coils  1219   c  and  1220   c , to which the AC voltage is induced from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1219   c  and  1220   c.    
   The input terminal of the diode  1233  is connected to one end of the paired third coils  1221   c  and  1222   c , to which the AC voltage is induced from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1221   c  and  1222   c.    
   The input terminal of the diode  1234  is connected to one end of the paired third coils  1223   c  and  1224   c , to which the AC voltage is induced from the primary coils  314   a  and  411   a  connected to different connectors  711  and  810 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1223   c  and  1224   c.    
   The input terminal of the diode  1235  is connected to one end of the paired third coils  1225   c  and  1226   c , to which the AC voltage is induced from the primary coils  412   a  and  413   a  connected to different connectors  810  and  811 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1225   c  and  1226   c.    
   The fault detector  120  is connected to output terminals of the eight diodes  1228 ,  1229 ,  1230 ,  1231 ,  1232 ,  1233 ,  1234  and  1235 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  1228 ,  1229 ,  1230 ,  1231 ,  1232 ,  1233 ,  1234  and  1235  with the predetermined threshold value so as to detect the fault and generates the comparison result. The comparison result is output by the indicator  121 . 
   Embodiment 13 
   Hereinafter, a thirteenth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 14  is a circuit diagram showing an inverter circuit and a backlight assembly according to the thirteenth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the third embodiment, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 14 , the backlight assembly  1300  according to the thirteenth embodiment of the present invention includes the inverter circuit  1310 , and six pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  1310  includes two inverters  111  and  112 , a first substrate  1320 , a second substrate  1330 , a first power supply line  1340  mounted on the first substrate  1320 , a second power supply line  1350  mounted on the second substrate  1330 , a connector  1360  that interconnects the substrates, first group balance transformers  1370  mounted on the first substrate  1320 , second group balance transforms  1380  mounted on the second substrate  1330 , and a fault detection device  1390 . 
   The first power supply line  1340  is connected to output terminals of the inverters  111  and  112  and input terminals of the first group balance transformers  1370 . The first group balance transformers  1370  are connected to three pairs of cold cathode fluorescent lamps  130 . In addition, the inverters  111  and  112  provide power to the three pairs of cold cathode fluorescent lamps  130  through the first power supply line  1340  and the first group balance transformers  1370 . 
   The second power supply line  1350  is connected to output terminals of the inverters  111  and  112  and input terminals of the second group balance transformers  1380 . The second group balance transformers  1380  are connected to three pairs of cold cathode fluorescent lamps  130 . In addition, the inverters  111  and  112  provide power to the three pairs of cold cathode fluorescent lamps  130  through the second power supply line  1350  and the second group balance transformers  1380 . 
   The connector  1360  electrically connects the first power supply line  1340  to the second power supply line  1350 . In addition, the connector  1360  electrically connects the first group balance transformers  1370  to the second group balance transformers  1380 . Further, the connector  1360  electrically connects a first fault detection unit  1391  of the fault detection device  1390  to a second fault detection unit  1392  of the fault detection device  1390 . 
   The first group balance transformers  1370  include six balance transformers  113 ,  114 ,  115 ,  116 ,  211  and  212 . The six balance transformers  113 ,  114 ,  115 ,  116 ,  211  and  212  have primary coils  113   a ,  114   a ,  115   a ,  116   a ,  211   a  and  212   a , which are connected between the first power supply line  1340  and three pairs of cold cathode fluorescent lamps  130 , respectively. The six balance transformers  113 ,  114 ,  115 ,  116 ,  211  and  212  have secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b  and  212   b , to which AC voltage is induced from the primary coils  113   a ,  114   a ,  115   a ,  116   a ,  211   a  and  212   a , respectively. Among the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b  and  212   b , adjacent secondary coils are serially connected to each other. 
   The second group balance transformers  1380  include six balance transformers  213 ,  214 ,  311 ,  312 ,  313  and  314 . The six balance transformers  213 ,  214 ,  311 ,  312 ,  313  and  314  have primary coils  213   a ,  214   a ,  311   a ,  312   a ,  313   a  and  314   a , which are connected between the second power supply line  1350  and three pairs of cold cathode fluorescent lamps  130 , respectively. The six balance transformers  213 ,  214 ,  311 ,  312 ,  313  and  314  have secondary coils  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b , to which AC voltage is induced from the primary coils  213   a ,  214   a ,  311   a ,  312   a ,  313   a  and  314   a , respectively. Among the secondary coils  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b , adjacent secondary coils are serially connected to each other. 
   In addition, the secondary coils of the first and second group balance transformers  1370  and  1380  are connected to the connector  1360  to form the secondary coil serial loop. A part of the secondary coil serial loop is connected to the ground GND. That is, six secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b  and  212   b  of the first group balance transformers  1370  are connected to the connector  1360  so as to form the secondary coil serial loop together with the six secondary coils  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b  of the second group balance transformers  1380 , and the second coil serial loop is partially connected to the ground GND. 
   The fault detection device  1390  detects high voltage abnormal discharge in the inverter circuit  1310 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1390  detects the abnormal operation based on the voltage detection values generated from voltages of the first and second group balance transformers  1370  and  1380 . 
   The fault detection device  1390  includes the first fault detection unit  1391 , the second fault detection unit  1392 , a fault detector  120  and an indicator  121 . 
   The first fault detection unit  1391  includes three pairs of third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c , and  212   c  and three diodes  118 ,  119  and  216 . 
   Among the third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c , and  212   c  of the first fault detection unit  1391 , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  113   c  and  114   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  113   c  and  114   c , and one end of the paired third coils  113   c  and  114   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  115   c  and  116   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  115   c  and  116   c , and one end of the paired third coils  115   c  and  116   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  211   c  and  212   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  211   c  and  212   c , and one end of the paired third coils  211   c  and  212   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   The second fault detection unit  1392  includes three pairs of third coils  213   c ,  214   c ,  311   c ,  312   c ,  313   c , and  314   c  and three diodes  217 ,  316  and  317 . 
   Among the third coils  213   c ,  214   c ,  311   c ,  312   c ,  313   c , and  314   c  of the second fault detection unit  1392 , paired third coils adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  213   c  and  214   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  213   c  and  214   c , and one end of the paired third coils  213   c  and  214   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  311   c  and  312   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  311   c  and  312   c , and one end of the paired third coils  311   c  and  312   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  313   c  and  314   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  313   c  and  314   c , and one end of the paired third coils  313   c  and  314   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In this manner, the third coils of the first fault detection unit  1391  are connected to the third coils of the second fault detection unit  1392  by means of the connector  1360 , and one end of the third coils of the first and second fault detection units  1391  and  1392  can be connected to the ground through the secondary coil serial loop. 
   Input terminals of the diodes  118 ,  119  and  216  of the first fault detection unit  1391  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  118  is connected to one end of the paired third coils  113   c  and  114   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  113   c  and  114   c.    
   The input terminal of the diode  119  is connected to the paired third coils  115   c  and  116   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  115   c  and  116   c.    
   The input terminal of the diode  216  is connected to the paired third coils  211   c  and  212   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  211   c  and  212   c.    
   In addition, input terminals of the diodes  217 ,  316  and  317  of the second fault detection unit  1392  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  217  is connected to one end of the paired third coils  213   c  and  214   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  213   c  and  214   c.    
   The input terminal of the diode  316  is connected to the paired third coils  311   c  and  312   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  311   c  and  312   c.    
   The input terminal of the diode  317  is connected to the paired third coils  313   c  and  314   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  313   c  and  314   c.    
   The fault detector  120  is connected to output terminals of the diodes  118 ,  119  and  216  of the first fault detection unit  1391  and output terminals of the diodes  217 ,  316  and  317  of the second fault detection unit  1392 . The fault detector  120  compares the voltage detection value generated from voltage of the diodes  118 ,  119 ,  216 ,  217 ,  316  and  317  with the predetermined threshold value so as to detect the fault and generates the comparison result. As described above, according to the thirteenth embodiment of the present invention, the connector for interconnecting the substrates electrically connects the first and second power supply lines, the first and second substrates, the first and second group balance transforms and the first and second fault detection units. In addition, among the plural third coils of each fault detection unit, the paired third coils adjacent to each other are serially connected to each other through the connector so as to offset the AC voltage generated from the paired third coils and one end of the paired third coils is connected to input terminals of the plural diodes. Thus, according to the thirteenth embodiment of the present invention, the backlight assembly can be fabricated in a large size without increasing the number of connector terminals interposed between substrates. Further, according to the thirteenth embodiment of the present invention, even if the number of the cold cathode fluorescent lamps increases due to the large-size backlight assembly, since the paired third coils adjacent to each other are serially connected to each other in each substrate so as to offset the AC voltage generated from the paired third coils, the abnormal operation of the backlight assembly can be more precisely detected. 
   Embodiment 14 
   Hereinafter, a fourteenth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 15  is a circuit diagram showing an inverter circuit and a backlight assembly according to the fourteenth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the fourth and thirteenth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 15 , the backlight assembly  1400  according to the fourteenth embodiment of the present invention includes the inverter circuit  1410 , and eight pairs of cold cathode fluorescent lamps (discharge tubes)  130 . 
   The inverter circuit  1410  includes two inverters  111  and  112 , a first substrate  1320 , a second substrate  1330 , a first power supply line  1340  mounted on the first substrate  1320 , a second power supply line  1350  mounted on the second substrate  1330 , a connector  1360  that interconnects the substrates, first group balance transformers  1420  mounted on the first substrate  1320 , second group balance transforms  1430  mounted on the second substrate  1330 , and a fault detection device  1440 . That is, the inverter circuit  1410  according to the fourteenth embodiment of the present invention is identical to the inverter circuit  1310  according to the thirteenth embodiment of the present invention, except for the structure of the first and second group balance transformers  1420  and  1430  and the fault detection device  1440 . 
   The connector  1360  electrically connects the first group balance transformers  1420  to the second group balance transformers  1430 . In addition, the connector  1360  electrically connects a first fault detection unit  1441  of the fault detection device  1440  to a second fault detection unit  1442  of the fault detection device  1440 . 
   The first group balance transformers  1420  include eight balance transformers  113 ,  114 ,  115 ,  116 ,  211 ,  212 ,  213  and  214 . That is, the first group balance transformers  1420  according to the fourteenth embodiment of the present invention further include two balance transformers  213  and  214  of the second group balance transformers  1380  according to the thirteenth embodiment of the present invention. 
   The two balance transformers  213  and  214  include primary coils  213   a  and  214   a , which are connected between the first power supply line  1340  and a pair of cold cathode fluorescent lamps  130 , respectively. In addition, the balance transformers  213  and  214  have secondary coils  213   b  and  214   b , to which AC voltage is induced from the primary coils  213   a  and  214   a . The secondary coils  213   b  and  214   b  are serially connected to each other. 
   The second group balance transformers  1430  include eight balance transformers  311 ,  312 ,  313 ,  314 ,  411 ,  412 ,  413  and  414 . That is, the second group balance transformers  1430  according to the fourteenth embodiment of the present invention have no two balance transformers  213  and  214  and further include four balance transformers  411 ,  412 ,  413  and  414  as compared with the second group balance transformers  1380  according to the thirteenth embodiment of the present invention. 
   The four balance transformers  411 ,  412 ,  413  and  414  include primary coils  411   a ,  412   a ,  413   a  and  414   a , which are connected between the second power supply line  1350  and two pairs of cold cathode fluorescent lamps  130 , respectively. In addition, the four balance transformers  411 ,  412 ,  413  and  414  have secondary coils  411   b ,  412   b ,  413   b  and  414   b , to which AC voltage is induced from the primary coils  411   a ,  412   a ,  413   a  and  414   a . Among the secondary coils  411   b ,  412   b ,  413   b  and  414   b , adjacent secondary coils are serially connected to each other. 
   In addition, sixteen secondary coils of the first and second balance transformers  1420  and  1430  are connected to the connector  1360  to form the serial loop of the secondary coils. A part of the secondary coil serial loop is connected to the ground GND. That is, eight secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b  and  214   b  of the first group balance transformers  1420  are connected to the connector  1360  so as to form the secondary coil serial loop together with the eight secondary coils  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b  of the second group balance transformers  1430 , and the second coil serial loop is partially connected to the ground GND. 
   The fault detection device  1440  detects high voltage abnormal discharge in the inverter circuit  1410 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1440  detects the abnormal operation based on the voltage detection values generated from voltages of the first and second group balance transformers  1420  and  1430 . 
   The fault detection device  1440  includes the first fault detection unit  1441 , the second fault detection unit  1442 , a fault detector  120  and an indicator  121 . 
   The first fault detection unit  1441  includes four pairs of third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c ,  212   c ,  213   c  and  214   c  and four diodes  118 ,  119 ,  216  and  217 . That is, the first fault detection unit  1441  further includes a pair of third coils  213   c  and  214   c  and the diode  217  of the second fault detection unit  1392  according to the thirteenth embodiment of the present invention. 
   Among the third coils  113   c ,  114   c ,  115   c ,  116   c ,  211   c ,  212   c ,  213   c  and  214   c  of the first fault detection unit  1441 , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b . In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  213   c  and  214   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  213   c  and  214   c , and one end of the paired third coils  213   c  and  214   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The second fault detection unit  1442  includes four pairs of third coils  311   c ,  312   c ,  313   c ,  314   c ,  411   c ,  412   c ,  413   c  and  414   c  and four diodes  316 ,  317 ,  416  and  417 . That is, the second fault detection unit  1442  according to the fourteenth embodiment of the present invention has no third coils  213   c  and  214   c , and further includes two pairs of third coils  411   c ,  412   c ,  413   c  and  414   c  as compared with the second fault detection unit  1392  according to the thirteenth embodiment of the present invention. In addition, the second fault detection unit  1442  according to the fourteenth embodiment of the present invention has no diode  217 , and further includes two diodes  416  and  417  as compared with the second fault detection unit  1392  according to the thirteenth embodiment of the present invention. 
   Among the third coils  311   c ,  312   c ,  313   c ,  314   c ,  411   c ,  412   c ,  413   c  and  414   c  of the second fault detection unit  1442 , adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b . In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  411   c  and  412   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  411   c  and  412   c , and one end of the paired third coils  411   c  and  412   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In addition, the paired third coils  413   c  and  414   c  adjacent to each other are serially connected to each other so as to offset AC voltage generated from the paired third coils  413   c  and  414   c , and one end of the paired third coils  411   c  and  412   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In this manner, the third coils of the first fault detection unit  1441  are connected to the third coils of the second fault detection unit  1442  by means of the connector  1360 , and one end of the third coils of the first and second fault detection units  1441  and  1442  can be connected to the ground through the secondary coil serial loop. 
   Input terminals of the four diodes  118 ,  119 ,  216  and  217  of the first fault detection unit  1441  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  217  is connected to one end of the paired third coils  213   c  and  214   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  213   c  and  214   c.    
   In addition, input terminals of the diodes  316 ,  317 ,  416  and  417  of the second fault detection unit  1442  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  416  is connected to one end of the paired third coils  411   c  and  412   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  411   c  and  412   c.    
   In addition, the input terminal of the diode  417  is connected to the paired third coils  413   c  and  414   c  in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  413   c  and  414   c.    
   The fault detector  120  is connected to output terminals of the diodes  118 ,  119   216  and  217  of the first fault detection unit  1441  and output terminals of the diodes  316 ,  317 ,  416  and  417  of the second fault detection unit  1442 . The fault detector  120  compares the voltage detection value generated from voltage of the eight diodes  118 ,  119 ,  216 ,  217 ,  316 ,  317 ,  416  and  417  with the predetermined threshold value so as to detect the fault and generates the comparison result. 
   Embodiment 15 
   Hereinafter, a fifteenth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 16  is a circuit diagram showing an inverter circuit and a backlight assembly according to the fifteenth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the eleventh and thirteenth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 16 , the backlight assembly  1500  according to the fifteenth embodiment of the present invention includes the inverter circuit  1510 , six pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and six connectors  510 ,  511 ,  610 ,  611 ,  710  and  711 . 
   The inverter circuit  1510  includes two inverters  111  and  112 , a first substrate  1320 , a second substrate  1330 , a first power supply line  1340  mounted on the first substrate  1320 , a second power supply line  1350  mounted on the second substrate  1330 , a connector  1360  that interconnects the substrates, first group balance transformers  1370  mounted on the first substrate  1320 , second group balance transforms  1380  mounted on the second substrate  1330 , and a fault detection device  1520 . That is, the inverter circuit  1510  according to the fifteenth embodiment of the present invention is identical to the inverter circuit  1310  according to the thirteenth embodiment of the present invention, except for the structure of the fault detection device  1520 . 
   The fault detection device  1520  detects high voltage abnormal discharge in the inverter circuit  1510 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1520  detects the abnormal operation based on the voltage detection values generated from voltages of the first and second group balance transformers  1370  and  1380 . 
   The fault detection device  1520  includes a first fault detection unit  1521 , a second fault detection unit  1522 , a fault detector  120  and an indicator  121 . The first fault detection unit  1521  is electrically connected to the second fault detection unit  1522  through the connector  1360 . 
   The first fault detection unit  1521  includes three pairs of third coils  1523   c ,  1524   c ,  1525   c ,  1526   c ,  1527   c , and  1528   c  and three diodes  1529 ,  1530  and  1531 . 
   Among the third coils  1523   c ,  1524   c ,  1525   c ,  1526   c ,  1527   c , and  1528   c  of the first fault detection unit  1521 , paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1523   c  and  1528   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1523   c  and  1528   c , in which the AC voltage is induced to the paired third coils  1523   c  and  1528   c  from the primary coils  113   a  and  212   a  connected to different connectors  510  and  610 , respectively. In addition, one end of the paired third coils  1523   c  and  1528   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  1524   c  and  1525   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1524   c  and  1525   c , in which the AC voltage is induced to the paired third coils  1524   c  and  1528   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , respectively. In addition, one end of the paired third coils  1524   c  and  1525   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  1526   c  and  1527   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1526   c  and  1527   c , in which the AC voltage is induced to the paired third coils  1526   c  and  1527   c  from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , respectively. In addition, one end of the paired third coils  1526   c  and  1527   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   The second fault detection unit  1522  includes three pairs of third coils  1532   c ,  1533   c ,  1534   c ,  1535   c ,  1536   c , and  1537   c  and three diodes  1538 ,  1539  and  1540 . 
   Among the third coils  1532   c ,  1533   c ,  1534   c ,  1535   c ,  1536   c , and  1537   c  of the second fault detection unit  1522 , paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1532   c  and  1537   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1532   c  and  1537   c , in which the AC voltage is induced to the paired third coils  1532   c  and  1537   c  from the primary coils  213   a  and  314   a  connected to different connectors  611  and  711 , respectively. In addition, one end of the paired third coils  1532   c  and  1537   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In addition, the paired third coils  1533   c  and  1534   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1533   c  and  1534   c , in which the AC voltage is induced to the paired third coils  1533   c  and  1534   c  from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 , respectively. In addition, one end of the paired third coils  1533   c  and  1534   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   Further, the paired third coils  1535   c  and  1536   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1535   c  and  1536   c , in which the AC voltage is induced to the paired third coils  1535   c  and  1536   c  from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , respectively. In addition, one end of the paired third coils  1535   c  and  1536   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b  and  314   b.    
   In this manner, the third coils of the first fault detection unit  1521  are connected to the third coils of the second fault detection unit  1522  by means of the connector  1360 , and one end of the third coils of the first and second fault detection units  1521  and  1522  can be connected to the ground through the secondary coil serial loop. 
   Input terminals of the three diodes  1529 ,  1530  and  1531  of the first fault detection unit  1521  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1529  is connected to one end of the paired third coils  1523   c  and  1528   c , to which the AC voltage is induced from the primary coils  113   a  and  212   a  connected to different connectors  510  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1523   c  and  1528   c.    
   In addition, the input terminal of the diode  1530  is connected to one end of the paired third coils  1524   c  and  1525   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1524   c  and  1525   c.    
   Further, the input terminal of the diode  1531  is connected to one end of the paired third coils  1526   c  and  1527   c , to which the AC voltage is induced from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1526   c  and  1527   c.    
   Input terminals of the three diodes  1538 ,  1539  and  1540  of the second fault detection unit  1522  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1538  is connected to one end of the paired third coils  1532   c  and  1537   c , to which the AC voltage is induced from the primary coils  213   a  and  314   a  connected to different connectors  611  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1532   c  and  1537   c.    
   In addition, the input terminal of the diode  1539  is connected to one end of the paired third coils  1533   c  and  1534   c , to which the AC voltage is induced from the primary coils  214   a  and  311   a  connected to different connectors  611  and  710 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1533   c  and  1534   c.    
   Further, the input terminal of the diode  1540  is connected to one end of the paired third coils  1535   c  and  1536   c , to which the AC voltage is induced from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1535   c  and  1536   c.    
   The fault detector  120  is connected to output terminals of the diodes  1529 ,  1530  and  1531  of the first fault detection unit  1521  and output terminals of the diodes  1538 ,  1539  and  1540  of the second fault detection unit  1522 . The fault detector  120  compares the voltage detection value generated from voltage of the six diodes  1529 ,  1530 ,  1531 ,  1538 ,  1539  and  1540  with the predetermined threshold value so as to detect the fault and generates the comparison result. 
   As described above, according to the fifteenth embodiment of the present invention, the connector for interconnecting substrates electrically connects the first and second power supply lines, the first and second substrates, the first and second group balance transforms and the first and second fault detection units. In addition, among the plural third coils of each fault detection unit, the paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other through the connector so as to offset the AC voltage generated from the paired third coils and one end of the paired third coils is connected to input terminals of the plural diodes. Thus, according to the thirteenth embodiment of the present invention, the backlight assembly can be fabricated in a large size without increasing the number of connector terminals interposed between substrates. 
   Further, according to the fifteenth embodiment of the present invention, even if the number of the cold cathode fluorescent lamps increases due to the large-size backlight assembly and the opening fault occurs in the connector that combines a pair of cold cathode fluorescent lamps, since the third coil, to which the AC voltage is induced from the primary coil connected between one connector and the output terminal of the inverter, is serially connected to another third coil, to which the AC voltage is induced from the primary coil connected to the other connector, AC voltages generated from the paired third coils are offset from each other in each substrate and the abnormal operation of the backlight assembly can be more precisely detected. 
   Embodiment 16 
   Hereinafter, a sixteenth embodiment of the present invention will be described in detail with reference to accompanying drawings.  FIG. 17  is a circuit diagram showing an inverter circuit and a backlight assembly according to the sixteenth embodiment of the present invention. The same reference numerals will be assigned to the elements identical to the elements shown in the twelfth and fourteenth embodiments, and detailed description thereof will be omitted in order to avoid redundancy. 
   As shown in  FIG. 17 , the backlight assembly  1600  according to the sixteenth embodiment of the present invention includes the inverter circuit  1610 , eight pairs of cold cathode fluorescent lamps (discharge tubes)  130 , and eight connectors  510 ,  511 ,  610 ,  611 ,  710 ,  711 ,  810  and  811 . 
   The inverter circuit  1610  includes two inverters  111  and  112 , a first substrate  1320 , a second substrate  1330 , a first power supply line  1340  mounted on the first substrate  1320 , a second power supply line  1350  mounted on the second substrate  1330 , a connector  1360  that interconnects the substrates, first group balance transformers  1420  mounted on the first substrate  1320 , second group balance transforms  1430  mounted on the second substrate  1330 , and a fault detection device  1620 . That is, the inverter circuit  1610  according to the sixteenth embodiment of the present invention is identical to the inverter circuit  1410  according to the fourteenth embodiment of the present invention, except for the structure of the fault detection device  1620 . 
   The fault detection device  1620  detects high voltage abnormal discharge in the inverter circuit  1610 , such as corona discharge and arc discharge, which are generated when a defect occurs in an insulator provided between a high voltage section and the ground GND. The fault detection device  1620  detects the abnormal operation based on the voltage detection values generated from voltages of the first and second group balance transformers  1420  and  1430 . 
   The fault detection device  1620  includes a first fault detection unit  1621 , a second fault detection unit  1622 , a fault detector  120  and an indicator  121 . The first fault detection unit  1621  is electrically connected to the second fault detection unit  1622  through the connector  1360 . 
   The first fault detection unit  1621  includes four pairs of third coils  1622   c ,  1623   c ,  1624   c ,  1625   c ,  1626   c ,  1627   c ,  1628   c  and  1629   c  and four diodes  1630 ,  1631 ,  1632  and  1633 . 
   Among the third coils  1622   c ,  1623   c ,  1624   c ,  1625   c ,  1626   c ,  1627   c ,  1628   c  and  1629   c  of the first fault detection unit  1621 , paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1622   c  and  1629   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1622   c  and  1629   c , in which the AC voltage is induced to the paired third coils  1622   c  and  1629   c  from the primary coils  113   a  and  214   a  connected to different connectors  510  and  611 , respectively. In addition, one end of the paired third coils  1622   c  and  1629   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In addition, the paired third coils  1623   c  and  1624   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1623   c  and  1624   c , in which the AC voltage is induced to the paired third coils  1623   c  and  1624   c  from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , respectively. In addition, one end of the paired third coils  1623   c  and  1624   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Further, the paired third coils  1625   c  and  1626   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1625   c  and  1626   c , in which the AC voltage is induced to the paired third coils  1625   c  and  1626   c  from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , respectively. In addition, one end of the paired third coils  1625   c  and  1626   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Furthermore, the paired third coils  1627   c  and  1628   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1627   c  and  1628   c , in which the AC voltage is induced to the paired third coils  1627   c  and  1628   c  from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 , respectively. In addition, one end of the paired third coils  1627   c  and  1628   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   The second fault detection unit  1622  includes four pairs of third coils  1634   c ,  1635   c ,  1636   c ,  1637   c ,  1638   c ,  1639   c ,  1640   c  and  1641   c  and four diodes  1642 ,  1643 ,  1644  and  1645 . 
   Among the third coils  1634   c ,  1635   c ,  1636   c ,  1637   c ,  1638   c ,  1639   c ,  1640   c  and  1641   c  of the second fault detection unit  1622 , paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so as to offset AC voltage generated from the paired third coils, and one end of the paired third coils is connected to the secondary coil serial loop. In addition, one end of the paired third coils can be directly connected to the ground GND, other than connected to the ground GND through the secondary coil serial loop. 
   That is, the paired third coils  1634   c  and  1641   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1634   c  and  1641   c , in which the AC voltage is induced to the paired third coils  1634   c  and  1641   c  from the primary coils  311   a  and  414   a  connected to different connectors  710  and  811 , respectively. In addition, one end of the paired third coils  1634   c  and  1641   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In addition, the paired third coils  1635   c  and  1636   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1635   c  and  1636   c , in which the AC voltage is induced to the paired third coils  1635   c  and  1636   c  from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , respectively. In addition, one end of the paired third coils  1635   c  and  1636   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Further, the paired third coils  1637   c  and  1638   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1637   c  and  1638   c , in which the AC voltage is induced to the paired third coils  1637   c  and  1638   c  from the primary coils  314   a  and  411   a  connected to different connectors  711  and  810 , respectively. In addition, one end of the paired third coils  1637   c  and  1638   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   Furthermore, the paired third coils  1639   c  and  1640   c  are serially connected to each other so as to offset AC voltage generated from the paired third coils  1639   c  and  1640   c , in which the AC voltage is induced to the paired third coils  1639   c  and  1640   c  from the primary coils  412   a  and  413   a  connected to different connectors  810  and  811 , respectively. In addition, one end of the paired third coils  1639   c  and  1640   c  is connected to the ground GND by way of the serial loop of the secondary coils  113   b ,  114   b ,  115   b ,  116   b ,  211   b ,  212   b ,  213   b ,  214   b ,  311   b ,  312   b ,  313   b ,  314   b ,  411   b ,  412   b ,  413   b  and  414   b.    
   In this manner, the third coils of the first fault detection unit  1621  are connected to the third coils of the second fault detection unit  1622  by means of the connector  1360 , and one end of the third coils of the first and second fault detection units  1621  and  1622  can be connected to the ground through the secondary coil serial loop. 
   Input terminals of the four diodes  1630 ,  1631 ,  1632  and  1633  of the first fault detection unit  1621  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1630  is connected to one end of the paired third coils  1622   c  and  1629   c , to which the AC voltage is induced from the primary coils  113   a  and  214   a  connected to different connectors  510  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1622   c  and  1629   c.    
   In addition, the input terminal of the diode  1631  is connected to one end of the paired third coils  1623   c  and  1624   c , to which the AC voltage is induced from the primary coils  114   a  and  115   a  connected to different connectors  510  and  511 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1623   c  and  1624   c.    
   Further, the input terminal of the diode  1632  is connected to one end of the paired third coils  1625   c  and  1626   c , to which the AC voltage is induced from the primary coils  116   a  and  211   a  connected to different connectors  511  and  610 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1625   c  and  1626   c.    
   Furthermore, the input terminal of the diode  1633  is connected to one end of the paired third coils  1627   c  and  1628   c , to which the AC voltage is induced from the primary coils  212   a  and  213   a  connected to different connectors  610  and  611 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1627   c  and  1628   c.    
   Input terminals of the four diodes  1642 ,  1643 ,  1644  and  1645  of the second fault detection unit  1622  are connected to one end of the paired third coils so as to detect ripple voltage generated from the paired third coils and then produce the voltage detection value. 
   That is, the input terminal of the diode  1642  is connected to one end of the paired third coils  1634   c  and  1641   c , to which the AC voltage is induced from the primary coils  311   a  and  414   a  connected to different connectors  710  and  811 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1634   c  and  1641   c.    
   In addition, the input terminal of the diode  1643  is connected to one end of the paired third coils  1635   c  and  1636   c , to which the AC voltage is induced from the primary coils  312   a  and  313   a  connected to different connectors  710  and  711 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1635   c  and  1636   c.    
   Further, the input terminal of the diode  1644  is connected to one end of the paired third coils  1637   c  and  1638   c , to which the AC voltage is induced from the primary coils  314   a  and  411   a  connected to different connectors  711  and  810 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1637   c  and  1638   c.    
   Furthermore, the input terminal of the diode  1645  is connected to one end of the paired third coils  1639   c  and  1640   c , to which the AC voltage is induced from the primary coils  412   a  and  413   a  connected to different connectors  810  and  811 , in order to produce the voltage detection value by detecting the ripple voltage generated from the paired third coils  1639   c  and  1640   c.    
   The fault detector  120  is connected to output terminals of the diodes  1630 ,  1631 ,  1632  and  1633  of the first fault detection unit  1621  and output terminals of the diodes  1642 ,  1643 ,  1644  and  1645  of the second fault detection unit  1622 . The fault detector  120  compares the voltage detection value generated from voltage of the eight diodes  1630 ,  1631 ,  1632 ,  1633 ,  1642 ,  1643 ,  1644  and  1645  with the predetermined threshold value so as to detect the fault and generates the comparison result. 
   Although the first to sixteenth embodiments of the present invention have been described in relation to the backlight assembly having four to sixteen cold cathode fluorescent lamps, which are provided as pairs, the present invention is also applicable for the backlight assembly having eighteen cathode fluorescent lamps or more, which are provided as pairs. 
   According to the inverter circuit and the backlight assembly described above, the paired third coils, which are adjacent to each other, are serially connected to each other so as to offset the AC voltage generated from the paired third coils, and one end of the paired third coils is connected to input terminals of the plural diodes. In addition, the fault detector compares the voltage detection value generated from voltages of the plural diodes with the predetermined threshold value to detect the fault and transmits the comparison result to the indicator. Further, even if the voltage rises in the backlight assembly due to impedance variation caused by the temperature gradient, the threshold value used to detect the abnormal operation of the backlight assembly can be appropriately set and the abnormal operation can be precisely detected. 
   That is, when impedance variation occurs due to the temperature gradient in the plural cold cathode fluorescent lamps, each paired third coils may generate voltages different from each other due to the difference in impedance, but AC voltages generated from the paired third coils, which are adjacent to each other, are offset from each other, so the threshold value can be set based on the differential voltage between the paired third coils. Thus, as compared with the conventional art, the abnormal operation of the backlight assembly can be precisely detected even if the threshold value is set to a low level. Therefore, since the threshold value used to detect the abnormal operation of the backlight assembly can be appropriately set, voltage variation can be precisely detected even if the voltage is slightly increased due to arc discharge caused by the opening fault and is below the threshold value under a condition of the conventional art. Thus, the abnormal operation of the backlight assembly can be precisely detected. 
   In addition, since only one diode is required for the paired third coils, which are adjacent to each other, the number of diodes can be reduced as compared with the prior art in which the diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   Further, when the plural cold cathode fluorescent lamps are connected to the balance transformers, two cold cathode fluorescent lamps are combined by means of the connector, so workability can be improved when installing or exchanging the cold cathode fluorescent lamps and the manufacturing cost can be reduced. 
   In addition, according to the backlight assembly described above, the paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other so as to offset the AC voltage generated from the paired third coils, and one end of the paired third coils is connected to input terminals of the plural diodes. In addition, the fault detector compares the voltage detection value generated from voltage of the plural diodes with the predetermined threshold value to detect the fault and transmits the comparison result to the indicator. Accordingly, even if the opening fault occurs in the pair of cold cathode fluorescent lamps in the backlight assembly, the threshold value used to detect the abnormal operation of the backlight assembly can be appropriately set and the abnormal operation can be precisely detected. 
   In other words, when the opening fault occurs in the connector that combines a pair of cold cathode fluorescent lamps, since the third coil, to which the AC voltage is induced from the primary coil connected between one connector and the output terminal of the inverter, is serially connected to another third coil, to which the AC voltage is induced from the primary coil connected to the other connector, so as to offset the AC voltage generated from the paired third coils, the abnormal operation of the backlight assembly can be precisely detected. 
   In addition, since only one diode is required for the paired third coils, the number of diodes can be reduced as compared with the prior art in which the diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   According to the backlight assembly having the above structure, the connector for interconnecting substrates electrically connects the first and second power supply lines, the first and second substrates, the first and second group balance transforms and the first and second fault detection units. In addition, among the plural third coils of each fault detection unit, adjacent third coils, which are aligned as a pair, are serially connected to each other through the connector so as to offset the AC voltage generated from the paired third coils and one end of the paired third coils is connected to input terminals of the plural diodes. Thus, the backlight assembly can be fabricated in a large size without increasing the number of connector terminals interposed between substrates. 
   Further, even if the number of the cold cathode fluorescent lamps increases due to the large-size backlight assembly, since the adjacent third coils, which are aligned as a pair, are serially connected to each other so as to offset the AC voltage generated from the paired third coils, the abnormal operation of the backlight assembly can be more precisely detected. 
   In addition, since only one diode is required for the paired third coils, the number of diodes can be reduced as compared with the prior art in which the diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   Further, according to the backlight assembly described above, the connector for interconnecting substrates electrically connects the first and second power supply lines, the first and second substrates, the first and second group balance transforms and the first and second fault detection units. In addition, among the plural third coils of the first and second fault detection units, the paired third coils, to which the AC voltage is induced from the primary coils connected to different connectors, are serially connected to each other through the connector so as to offset the AC voltage generated from the paired third coils and one end of the paired third coils is connected to input terminals of the plural diodes. Thus, the backlight assembly can be fabricated in a large size without increasing the number of connector terminals interposed between substrates. 
   In addition, even if the number of the cold cathode fluorescent lamps increases due to the large-size backlight assembly and the opening fault occurs in the connector that combines a pair of cold cathode fluorescent lamps, since the third coil, to which the AC voltage is induced from the primary coil connected between one connector and the output terminal of the inverter, is serially connected to another third coil, to which the AC voltage is induced from the primary coil connected to the other connector, in each substrate so as to offset the AC voltage generated from the paired third coils, the abnormal operation of the backlight assembly can be more precisely detected. 
   Further, since only one diode is required for the paired third coils, the number of diodes can be reduced as compared with the prior art in which the diode is provided for each third coil. Accordingly, the circuit structure can be simplified and the manufacturing cost can be reduced. 
   According to the present invention, the abnormal operation of the backlight assembly can be precisely detected, even if the voltage rises in the backlight assembly due to impedance variation caused by the temperature gradient. 
   Although the exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed.