Patent Publication Number: US-2011063274-A1

Title: Backlight assembly and display apparatus having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application relies for priority upon Korean Patent Application No. 2009-86619 filed on Sep. 14, 2009, the contents of which are herein incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field of Disclosure 
     The present disclosure of invention relates to a backlight assembly and an image display apparatus having the same. More particularly, the present disclosure relates to a backlight assembly capable of reducing the number of parts therein and improving brightness uniformity thereof and a display apparatus having the backlight assembly. 
     2. Description of Related Technology 
     A liquid crystal display (LCD) includes a liquid crystal display panel structured for displaying a signal-defined image and a backlight assembly providing a light to the liquid crystal display panel. 
     As a light source for the backlight assembly, cold cathode fluorescent lamps have been widely used. According to the employed arrangement of its light sources, the backlight assembly may be classified as an edge-illumination type backlight assembly in which a lamp is positioned adjacent to an edge of the liquid crystal display panel or as a direct-illumination type backlight assembly in which a plurality of lamps is positioned underneath the liquid crystal display panel. 
     Recently, as sizes of liquid crystal display panels have become larger, the direct-illumination type backlight assembly has been widely used for a display apparatus which requires high brightness. 
     The conventional direct-illumination type backlight assembly employs straight-line-shaped lamps in order to obtain the desired high brightness and brightness uniformity as well as compact packing of lamps, one adjacent to the next. 
     SUMMARY 
     In accordance with the present disclosure, a backlight assembly is provided that has a reduced number of parts therein (as compared to backlight assembly employing straight-line-shaped lamps) and which provides improved brightness uniformity to the overlying LCD panel. 
     According to exemplary embodiment, a backlight assembly includes a container having grounded electrically conductive parts; a plurality of lamps each having one or more bends and linear lamp segments extending from the one or more bends to thus define a corresponding lightable length of the lamp, the lamps being contained and positioned in the container such that their respective linear lamp segments all extend substantially in a first direction (D 1 ) so as to be substantially parallel to one another, each of the lamps having a first electrical terminal (H) for receiving a voltage of relatively high absolute magnitude and a second electrical terminal (G) for receiving a voltage of relatively low absolute magnitude where the different between the received high and low voltage magnitudes is sufficient to keep that lamp lit; and a voltage step-up transformer circuit having one or more output windings, each output winding having at least two output terminals (O 1 , O 2 ) where between there can develop as a result of a predetermined input AC voltage being applied to the step-up transformer circuit, an AC output voltage (V out12 ) of sufficient magnitude to light a connected series of at least two of the lamps, wherein for a given winding, said connected series of at least two lamps is formed by a corresponding two or more of the bent lamps each having the second electrical terminal thereof (the G terminal thereof) connected to an adjacent and grounded electrically conductive part of the container and having the first electrical terminal thereof (the H terminal thereof) connected to a corresponding one of the at least two output terminals of the given winding. In one embodiment, the second terminal (the G terminal) of an outermost first lamp among the contained lamps is positioned close to a corresponding first grounded sidewall of the container and the second terminal (the G terminal) of an outermost second lamp among the contained lamps is positioned close to a corresponding second grounded sidewall of the container while the respective first electrical terminals (the H terminals) of the first and second outermost lamps are positioned substantially far away from the first and second grounded sidewalls of the container so that electrostatic leakage current is not easily discharged from the high-voltage receiving first electrical terminals (the H terminals) of the first and second outermost lamps to the grounded first and second sidewalls of the container. 
     Other aspects of the present teachings will be more readily appreciated from the following detailed description. It will be seen that lamp segment brightness near the grounded sidewalls of the container may be prevented from being deteriorated by electrostatic discharge by virtue of this arrangement, thereby improving brightness uniformity of the backlight assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present teachings will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a plan view showing a backlight assembly according to a first exemplary embodiment; 
         FIG. 2  is a circuit diagram showing a connection relation between a transformer circuit and a plurality of lamps of  FIG. 1 ; 
         FIG. 3  is a plan view showing a backlight assembly according to another exemplary embodiment; 
         FIG. 4  is a circuit diagram showing a connection relation between a transformer circuit and a plurality of lamps of  FIG. 3 . 
         FIG. 5  is a plan view showing a display apparatus employing a backlight assembly of  FIG. 1 ; 
         FIG. 6  is a diagram showing brightness measurement points for brightness values of a display panel of  FIG. 5 ; 
         FIGS. 7A and 7B  are tables showing brightness values measured at brightness measurement points of  FIG. 6 ; 
         FIG. 8  is a plan view showing a backlight assembly according to another exemplary embodiment; and 
         FIG. 9  is a circuit diagram showing a connection relation between a transformer circuit and a plurality of lamps of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the present teachings. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms, “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure most closely pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, the present disclosure is provided in greater detail with reference to the accompanying drawings. 
       FIG. 1  is a plan view showing a backlight assembly according to a first exemplary embodiment  100 .  FIG. 2  is a circuit diagram showing a possible connection relation between a transformer circuit and a plurality of lamps in one embodiment, according to  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the schematically illustrated backlight assembly  100  includes an electrically conductive container  110 , a plurality of lamps each having at least one U-type bend,  121 ,  122 ,  123 , and  124 , a transformer circuit  130 , and an inverter printed circuit board (PCB)  140 . 
     In one embodiment, the container  110  has a rectangular box shape and the lamps  121 ˜ 124  are contained in a containing space  110   a  of the container  110 . The illustrated exemplary embodiment  100  has four lamps, for example, a first lamp  121 , a second lamp  122 , a third lamp  123 , and a fourth lamp  124 , each having a single U-bend at a right side thereof as shown in  FIG. 1 . However, the number of the lamps in other embodiments need not be limited to four and the number of U-type bends need not be limited to one. That is, in case that a size of the backlight assembly  100  becomes larger or a required brightness increases, the number of the lamps may increase to more than four. Also, since the first to fourth lamps  121 ˜ 124  have the same structure and function in the present exemplary embodiment, for the convenience of explanation, only the first lamp  121  will be described in greater detail as a representative example. 
     The first lamp  121  includes a high-voltage receiving, first terminal H 1  and a grounded second terminal G 1 , where the H 1  and G 1  terminals are respectively disposed at opposed ends of the longitudinal length of the first lamp  121  and where the H 1  and G 1  terminals are structured to receive a driving high-voltage signal that can cause the lamp  121  to light up. As an example, the illustrated first lamp  121  is bent once, so the first lamp  121  has a U-shape and includes two straight-line-shaped lamp segments  121   a  and  121   b  as well as an interposed bent segment that joins linear lamp segments  121   a  and  121   b . Thus, the first terminal H 1  and the second terminal G 1  of the first lamp  121  may be arranged at respective terminal ends of the linear lamp segments  121   a  and  121   b  so as to face a first adjacent sidewall  111  of the container  110 . 
     In other embodiments, the number of the straight-line-shaped lamp segments per lamp need not be limited to just two and may increase according to the size of the backlight assembly  100  and the required brightness. The lamp tubes proper may be in a first plane (parallel to the D 1 ˜D 2  plane) while their respective H and G terminals may bend down for connection in a second plane (PCB plane) disposed below the first plane. 
     Referring to  FIG. 2 , here the lamps are illustrated to be spaced unevenly due to other aspects of the schematic although it is to be understood that generally they will have their linear segments spaced according to a regular pitch interval for thereby providing a relatively uniform distribution of light intensity. The illustrated high-voltage transformer circuit  130  receives a relatively low voltage AC signal at its input side (left side) and it boosts the input AC voltage signal (V in ) to generate one or more high-voltage AC driving signals (V out12  and V out34 ) for application to corresponding high-voltage terminals H 1  and H 2  (shown receiving the V out12  signal) and to corresponding high-voltage terminals H 3  and H 4  (shown receiving the V out34  signal) of the respective first to fourth lamps  121 ˜ 124 . Of importance, the generated high-voltage AC driving signals (e.g., V out12 ) are each of sufficient voltage to ignite and/or keep lit a series connected circuit having two or more of the lamps connected series wise in that series connected circuit. In the present exemplary embodiment, the transformer circuit  130  may be a 4-out/2-in transformer having four output terminals and two input terminals, including for example, a first output terminal O 1 , a second output terminal O 2 , a third output terminal O 3 , and a fourth output terminal O 4 . (The high-voltage AC signals, V out12  and V out34 , developed at respective transformer output terminal pairs O 1 /O 2  and O 3 /O 4  are also referred to herein as high-voltage AC signals, V O12  and V O34  respectively.) 
     More specifically, and as shown, the first output terminal O 1  of transformer circuit  130  is connected to the first terminal H 1  of first lamp  121 , the second output terminal O 2  is connected to first terminal H 2  of second lamp  122 , the third output terminal O 3  is connected to first terminal H 3  of third lamp  123 , and the fourth output terminal O 4  is connected to first terminal H 4  of fourth lamp  124 . Thus, the one transformer circuit  130  may provide the driving power to the first to fourth lamps  121 ˜ 124 . Second terminals G 1 ˜G 4  of the first to fourth lamps  121 ˜ 124  are grounded. The G 1 -ground-G 2  connection completes the series-connected circuit which has V O12  driving AC current through its balanced loads, namely, lamps  121  and  122 . The G 3 -ground-G 4  connection completes the series circuit which has V O34  driving AC current through its balanced loads, namely, lamps  123  and  124 . 
     As described above, when the one transformer circuit  130  drives the four lamps  121 ˜ 124  as shown and described, the number of high-voltage transformer windings needed or lengths of high-voltage wires needed to be arranged across areas in the backlight assembly  100  decreases and the number of parts arranged on the inverter PCB  140  can be reduced, thereby decreasing a size of the inverter PCB  140 . 
     For example, an inverter PCB for a 32-inch display apparatus employing two transformers to drive four U-shaped lamps (one winding for each lamp, with that winding (not shown) having output voltage sufficient to drive no more than one lamp) has a size of about 386 mm by 63 mm or about 330 mm by 63 mm. However, as shown in the present exemplary embodiment, in case that the one transformer is used to drive the four U-shaped lamps (one high-voltage winding for every two, series-connected lamps), the size of the inverter PCB is reduced to have a size of about 243 mm by 63 mm (thus reducing the 386 mm original dimension by about 37%). As a consequence, the size of the inverter PCB may be advantageously decreased by decreasing the number of the transformers and increasing the number of lamps serviced by each high-voltage winding. 
     Meanwhile, the first to fourth lamps  121 ˜ 124  have their respectively linear segments (e.g.,  121   a ,  121   b ) extending a first direction D 1 , and the first to fourth lamps  121 ˜ 124  are packed one after the next in a second direction D 2  that is substantially perpendicular to the first direction D 1 . That is, the first to fourth lamps  121 ˜ 124  are arranged in the second direction D 2  in order of the first lamp  121 , then the second lamp  122 , the third lamp  123 , and finally the fourth lamp  124 . 
     The first lamp  121  that is positioned at an outermost position among the four lamps  121 ˜ 124  is the one most adjacent to top sidewall  112  of the container  110 , which is arranged in parallel to the first direction D 1 , and the fourth lamp  124  is the one that is positioned most adjacent to bottom sidewall  113  of the container  110 , which is opposite to the top sidewall  112 . The grounded second terminal G 1  of the first lamp  121  is closer to the also grounded top sidewall  112  than is the high-voltage first terminal H 1  of the first lamp  121 . Similarly, the grounded second terminal G 4  of the fourth lamp  124  is closer to the bottom sidewall  113  than is the first terminal H 4  of the fourth lamp  124 . 
     In general, the sidewalls of the container  110  are maintained at a ground potential. Thus, if hypothetically speaking, the first terminals H 1  and H 4  had been arranged more adjacent to the first and second sidewalls  112  and  113  of the container  110 , respectively, a larger leakage current (electrostatic breakdown leakage) would be generated as between the container  110  and the first and fourth lamps  121  and  124  positioned at both outermost positions. Such leakage currents can cause deterioration in brightness for the lamps disposed near the grounded first and second sidewalls  112  and  113  of the container  110 . 
     In order to prevent deterioration of the brightness, the first terminal H 1  of the first lamp  121  is arranged closer to a center portion of the container  110  than the second terminal G 1 , and the first terminal H 4  of the fourth lamp  124  is arranged closer to the center portion of the container  110  than the second terminal G 4 . Since the second terminals G 1  and G 4  receive a voltage that is relatively lower than the voltage applied to the first terminals H 1  and H 4 , the leakage current between the first lamp  121  and the first sidewall  112  and the leakage current between the fourth lamp  124  and the second sidewall  113  may be reduced. Therefore, the deterioration of the brightness of lamps near the first and second sidewalls  112  and  113  may be prevented, thereby improving brightness uniformity of the backlight assembly  100 . 
     In addition, the to be grounded, second terminals G 1  and G 4  of the first and fourth lamps  121  and  124  may directly make contact with the adjacent sidewall of container  110  to be thereby grounded through the container  110 . In addition, second terminals G 2  and G 3  of the second and third lamps  122  and  123  may be directly or indirectly connected to the second terminals G 1  and G 4  of the first and fourth lamps  121  and  124 . As described above, when the second terminals G 1 , G 2 , G 3 , and G 4  of the first to fourth lamps  121 ˜ 124  are grounded through the container  110 , no additional ground wiring needs to be used to ground the second terminals G 1 , G 2 , G 3 , and G 4  and there is no need to have grounding terminals on the inverter PCB  140  for connecting to the grounded second terminals G 1 , G 2 , G 3 , and G 4  of the lamps. That is, the ground terminal may be removed from the inverter PCB  140 , so that the size and cost of the inverter PCB  140  may be thus reduced. (Plug-in socket sets (not shown) into which the terminals of the U-shaped lamps are removably inserted may have one grounded-to-the-container socket that is also affixed to the bottom of the container and one HV socket that is insulated from the container for each lamp, thus simplifying connection operations during manufacture.) 
     As shown in  FIGS. 1 and 2 , the first terminal H 1  of the first lamp  121  is adjacent to the first terminal H 2  of the second lamp  122 , the first terminal H 3  of the third lamp  123  is adjacent to the first terminal H 4  of the fourth lamp  124 , and the second terminal G 2  of the second lamp  122  is adjacent to the second terminal G 3  of the third lamp  123 . Accordingly, the terminals of the first to fourth lamps  121 ˜ 124  may be arranged in order of “G 1 H 1 H 2 G 2 G 3 H 3 H 4 G 4 ”. In other words, grounded terminals are generally grouped together and high-voltage terminals are generally grouped together. 
     As illustrated in  FIG. 2 , the voltage phase applied to the first terminal of one (e.g., H 1 ) of two adjacent lamps has a respectively first phase (e.g., plus, +) that is opposite to the voltage phase (e.g., minus, −) applied to the first terminal of remaining one (e.g., H 2 ) of the two adjacent lamps. In other words, the first terminal H 1  of the first lamp  121  receives the driving power having a phase opposite to a phase of the driving power applied to the first terminal H 2  of the second lamp  122 , the first terminal H 2  of the second lamp  122  receives the driving power having a phase opposite to a phase of the driving power applied to the first terminal H 3  of the third lamp  123 , and the first terminal H 3  of the third lamp  123  receives the driving power having a phase opposite to a phase of the driving power applied to the first terminal H 4  of the fourth lamp  124 . Thus, electric field potentials cancel out between the adjacent lamps and a waterfall noise may be prevented from occurring between the two adjacent lamps. 
     Further, since a high voltage is applied to the first terminals H 1 , H 2 , H 3 , and H 4 , an area where the first terminals H 1 , H 2 , H 3 , and H 4  are adjacent to each other may have a relatively higher brightness than other areas. For example, in case that the terminals of the first to fourth lamps  121 ˜ 124  are arranged in the order of “G 1 H 1 H 2 G 2 G 3 H 3 H 4 G 4 ”, the brightness of upper and lower areas of a display screen of the display apparatus will not be relatively lower than the other areas. Therefore, the backlight assembly  100  having a structure in which the terminals are arranged as the above-mentioned may have an advantage in displaying subtitles in the lower area when used for a television monitor or a screen. 
       FIG. 3  is a plan view showing a backlight assembly according to another exemplary embodiment  101 .  FIG. 4  is a circuit diagram showing a connection relation between a transformer and a plurality of lamps of  FIG. 3 . In  FIGS. 3 and 4 , the same reference numerals denote the same elements in  FIGS. 1 and 2 , and thus the detailed descriptions of the same elements will be omitted. Basically, in  FIGS. 3-4 , H 2  and H 3  are grouped adjacent to one another in the middle of D 2  extent while in  FIGS. 1-2 , it is G 2  and G 3  that are grouped adjacent to one another in the middle. 
     Referring to  FIGS. 3 and 4 , a backlight assembly  101  according to the present exemplary embodiment has substantially the same structure as the backlight assembly  100  of  FIG. 1  except for arrangement order of terminals of the second and third lamps,  122 ˜ 123 . 
     Particularly, in the present exemplary embodiment, a first terminal H 2  of a second lamp  122  is adjacent to a first terminal H 3  of a third lamp  123 , a first terminal H 1  of a first lamp  121  is adjacent to a second terminal G 2  of the second lamp  122 , and a first terminal H 4  of a fourth lamp  124  is adjacent to a second terminal G 3  of the third lamp  123 . Thus, the terminals of the first to fourth lamps  121 ˜ 124  may be arranged in the order of “G 1 H 1 G 2 H 2 H 3 G 3 H 4 G 4 ”. 
     When the terminals are arranged in the order of “G 1 H 1 G 2 H 2 H 3 G 3 H 4 G 4 ”, the brightness may be presented at relatively high in a center of a display screen of the display apparatus. Thus, the backlight assembly  101  having the structure in which the terminals are arranged as the above-described may have an advantage when employed as a monitor or a display device of a notebook computer. 
       FIG. 5  is a plan view showing a display apparatus employing the backlight assembly of  FIG. 1 . In  FIG. 5 , the same reference numerals denote the same elements in  FIG. 1 , and thus the detailed descriptions of the same elements will be omitted. 
     Referring to  FIG. 5 , a display apparatus  300  includes a backlight assembly  100  generating a light and a display unit  200  receiving the light to display an image. The display unit  200  includes a display panel  210  and a printed circuit board  220  flexibly connected thereto. The display panel is disposed over the backlight assembly  100  and controls a transmittance of the light passing therethrough to display the desired image, and the flexibly attached printed circuit board  220  is rotated to be arranged at one side of the display panel  210  to output driving signals (e.g., data line driving signals and/or gate line driving signals) to a so-called TFT array substrate of the display panel  210 . 
     The display panel  210  may be a liquid crystal display panel that includes a lower substrate (TFT array substrate)  211 , an upper substrate (common electrode substrate)  212  facing the lower substrate  211 , and a liquid crystal layer disposed between the lower substrate  211  and the upper substrate  212 . The printed circuit board  220  is connected to the display panel  210  through a plurality of flexible tape carrier interconnect strips  230  and a plurality of driving chips  231  mounted on the tape carrier strips  230 , respectively. 
     Each of the driving chips  231  may be provided with a data driver built therein to output data line signals to the display panel  210 . In the present exemplary embodiment, a gate driver (not shown) that outputs gate line signals to the display panel  210  may be directly formed on and integrated with the display panel  210  through a thin film process. 
     In addition, the driving chips  231  may be mounted on the display panel  210  as a chip-on-glass structure. In this case, the driving chips  231  may be integrally formed in one chip. 
     The printed circuit board  220  may be mounted along the exterior of a sidewall of the container  110  when assembling the display apparatus  300 , and the inverter PCB  140  of the backlight assembly  100  may be also mounted along the exterior of the same sidewall side of the container  110 . When the size of the inverter PCB  140  decreases, a space use efficiency of the sidewall of the container  110  may be improved, thereby reducing a total thickness of the display apparatus  300 . 
       FIG. 6  is a diagram showing brightness measurement points for brightness values of the display panel of  FIG. 5 , and  FIGS. 7A and 7  B are tables showing brightness values measured at the brightness measurement points (nine sample points) of  FIG. 6 . Particularly,  FIG. 7A  shows brightness values measured at the display panel receiving the light from the backlight assembly  101  shown in  FIG. 3 , and  FIG. 7B  shows brightness values measured at a display panel receiving a light from a backlight assembly which employs a double-sided driving method in that a driving power is applied to a first terminal and a second terminal of a U-shaped lamp. 
     Referring to  FIG. 6 , nine brightness measure points are obtained by equally dividing a test display panel (like  210 ) by six times in an x-axis direction (D 1 ) and equally dividing by six times in a y-axis direction (D 2 ). That is, a first point P 1  corresponds to coordinates (1, 1), a second point P 2  corresponds to coordinates (3, 1), and a third point P 3  corresponds to coordinates (5, 1). Also, a fourth point P 4  corresponds to coordinates (1, 3), a fifth point P 5  corresponds to coordinates (3, 3), and a sixth point P 6  corresponds to coordinates (5, 3). A seventh point P 7  corresponds to coordinates (1, 5), an eighth point P 8  corresponds to coordinates (5, 3), and a ninth point P 9  corresponds to coordinates (5, 5). The test display panel need not have a working LCD panel in it or light diffusing plates because the thing being tested is merely the locally average luminance at the 9 sample points across the display area. 
     Accordingly, the first to third points P 1 ˜P 3  are positioned at an upper area of the display panel  210 , the fourth to sixth points P 4 ˜P 6  are positioned at a center area of the display panel  210 , and the seventh to ninth points P 7 ˜P 9  are positioned at a lower area of the display panel  210 . 
     Referring to  FIG. 7A , among the first to ninth points P 1 ˜P 9 , the highest brightness value of about 460.1 nit has been measured at the fifth point P 5 , and the lowest brightness value of about 405.9 nit has been measured at the first point P 1 . Also, a total average of the measured brightness values measured at the first to ninth points P 1 ˜P 9  has been of about 434.88 nit. 
     In addition, according to  FIG. 7A , a difference between the highest brightness value and the lowest brightness value has been computed at about 54.8 nit. 
     Referring to  FIG. 7B , among the first to ninth points P 1 ˜P 9 , the highest brightness value of about 461.3 nit has been measured at the fifth point P 5 , and the lowest brightness value of about 387.3 nit has been measured at the seventh point P 7 . Also, an average of the measured brightness values measured at the first to ninth points P 1 ˜P 9  has been of about 420.17 nit. 
     According to  FIG. 7B , a difference between the highest brightness value and the lowest brightness value has been computed at about 74 nit. Consequently, when the display panel employs the backlight assembly  101  according to the present disclosure, the average brightness value becomes higher and the difference between the highest brightness value and the lowest brightness value becomes smaller by about 20 nit. Thus, when the backlight assembly  101  is employed as a light source for the display panel, the brightness and the brightness uniformity may be improved. 
       FIG. 8  is a plan view showing a backlight assembly according to another exemplary embodiment.  FIG. 9  is a circuit diagram showing a connection relation between a transformer and a plurality of lamps of  FIG. 8 . 
     Referring to  FIGS. 8 and 9 , a backlight assembly  400  includes an electrically conductive container  410 , a plurality of multi-bend lamps  421  and  422 , a voltage step-up transformer circuit  430 , and a printed circuit inverter board  440  to which the transformer  430  is mounted where the PCB inverter board  440  is understood to have drive electronics (not shown) further mounted thereon for driving the step-up transformer circuit  430  with an AC input voltage signal. 
     As shown in  FIG. 8 , the container  410  has a rectangular shape and the lamps  421  and  422  are contained in a containing space  410   a  of the container  410 . In  FIG. 8 , two lamps, for example, a first lamp  421  and a second lamp  422  have been shown, but the number of the lamps should not be limited thereto. That is, in case that the size of the backlight assembly  400  becomes larger or the required brightness increases, the number of the lamps may increase. Hereinafter, since the first lamp  421  and the second lamp  422  have the same structure and function (but are mounted in mirror image symmetry relative to one another), for the convenience of explanation, the first lamp  421  will be described in detail as a representative example. 
     The first lamp  421  includes a first terminal H 1  (high-voltage terminal) and a second terminal G 1  (grounded terminal) respectively at the opposed ends of its multiply-bent length. In the present exemplary embodiment, the first lamp  421  is bent twice, so the first lamp  421  has an S-shape and includes three straight-line-shaped lamp segments  421   a ,  421   b , and  421   c  that each are extended in a first direction D 1  and where the linear segments are arranged one after the other in a second direction D 2 . 
     A first straight-line-shaped lamp segment  421   a  and a second straight-line-shaped lamp segment  421   b , each of which is positioned at an outermost position among the three straight-line-shaped lamp segments  421   a ,  421   b , and  421   c  of that lamp, are respectively provided with the first terminal H 1  and the second terminal G 1 . More particularly, the first straight-line-shaped lamp segment  421   a  is connected via the first terminal H 1  to a corresponding high-voltage output node (O 1 ) of the step-up transformer circuit  430 . The second straight-line-shaped lamp segment  421   b  is connected via the second terminal G 1  to a grounded point at the bottom and/or inner sidewall ( 412 ) of the electrically conductive container  410 . The first terminal H 1  is positioned adjacent to the left sidewall  411  of the container  410  and the second terminal G 1  is positioned adjacent to an opposite sidewall  414  of the container  410 . Similar to the number of the lamps, the number of the straight-line-shaped lamp segments should not be limited to the illustrated number, and the number of the straight-line-shaped lamp segments may increase according to the size of the backlight assembly  400  and the required brightness. Also, in case that bending times of the each lamp increase, the number of the lamps disposed in the backlight assembly  400  may reduce. 
     Referring to  FIG. 9 , the transformer circuit  430  boosts an input AC voltage to a driving AC voltage and provides the boosted driving voltage to the first terminals H 1  and H 2  of the first and second lamps  421  and  422 . In the present exemplary embodiment, the transformer circuit  430  may be a 2-in-2-out transformer having two input terminals and two higher-voltage output terminals, for example, a first output terminal O 1  and a second output terminal O 2 . 
     In this case, the first output terminal O 1  of the transformer  430  is connected to the first terminal H 1  of the first lamp  421  and the second output terminal O 2  is connected to the first terminal H 2  of the second lamp  422 . Therefore, the one transformer circuit  430  may apply the driving current of appropriate voltage and power to the first lamp  421  and the second lamp  422  where the current loop completes by virtue of the mutual grounding of second terminals G 1  and G 2  of the lamps. The driving voltage signal applied to the first terminal H 1  of the first lamp  421  has a phase opposite to a phase of the driving voltage signal applied to the first terminal H 2  of the second lamp  422 . Thus, a waterfall noise may be prevented from occurring between the first lamp  421  and the second lamp  422 . 
     As described above, when the one transformer circuit  430  is configured to drive the first and second lamps  421  and  422 , the size of the transformer circuit  430  becomes smaller and the electrostatic leakage current at the output winding of the transformer circuit  430  arranged as shown in the backlight assembly  400  decreases because the high-voltage nodes, H 1  and H 2  can be spaced safely away from at least three of the sidewalls,  412 ,  413 ,  414  of the container  410 . In one embodiment, at least a central part of the left sidewall  411  may be made of an electrically insulative material such as a ceramic and/or a plastic so that the O 1  and O 2  wires of the transformer and the H 1  and H 2  terminals of the lamps can be safely spaced apart from grounded metal parts so as to reduce high-voltage leakage current therebetween. Since only the two transformer output wires, O 1  and O 2  (or corresponding terminal extensions thereof) need to connect to the lamps assembly  421 / 422 ; consequently, the number of the parts arranged on the PCB inverter board  440  may be reduced (e.g., by not requiring ground terminals), thereby decreasing the total size of the PCB inverter board  440 . In other words, when compared to the transformer circuit  130  that drives the first to fourth lamps  121 ˜ 124 , the transformer circuit  430  that drives the first and second lamps  421  and  422  has a small size and a half number of terminals although the transformer circuit  430  provides the light to the same area, and thus the size of the PCB inverter board  440  decreases by about 50% or more. 
     Meanwhile, each of the linear segments of the first and second lamps  421  and  422  is extended in a first direction D 1  and the linear segments are arranged one adjacent to the next in a second direction D 2  that is substantially perpendicular to the first direction D 1 . 
     As shown, the second terminal G 1  of the first lamp  421  is positioned closer to the top and right sidewalls  412 / 414  of the container  410  than is the first terminal H 1  thereof. Similarly, the second terminal G 2  of the second lamp  422  is positioned closer to the bottom and right sidewalls  413 / 414  of the container  410  than is the first terminal H 2  of the second lamp  422 . As a result, electric field intensity may gradually and smoothly decrease as one moves from the highest voltage (highest in terms of absolute magnitude) zones immediately around the H 1  and H 2  terminals and along the length of each lamp towards the grounded corner regions of the container where right sidewall  414  meets with top sidewall  412  or with bottom sidewall  413 . 
     In general, the wall of the container  410  are maintained at the ground potential (except that left sidewall  411  may have an electrically insulative portion through which wires O 1 , O 2  or equivalents thereof extend to meet up with lamp terminals H 1  and H 2 ). If hypothetically speaking, the first terminals H 1  and H 2  had instead been disposed more adjacent to the top and bottom sidewalls,  412  and  413  of the container  410 , a greater electrostatic leakage current may be generated between those sidewalls of the container  410  and adjacent lengths of the first and second lamps  421  and  422 . Such greater leakage current could cause deterioration in brightness near the top and bottom side walls  412  and  413  of the container  410  if that hypothetical arrangement had been used instead of one shown in  FIG. 8 . 
     Accordingly, in order to prevent or reduce such undesirable leakage current, the first terminal H 1  of the first lamp  421  is positioned closer to a left central portion of the container and the first terminal H 2  of the second lamp  422  is also positioned closer to the left central portion of the container  410  while the grounded terminals G 1  and G 2  are disposed more adjacent to the well grounded top and bottom right corners of the container  410 . Since the second terminals G 1  and G 2  receive a voltage having a relatively lower level than a voltage applied to the first terminals H 1  and H 2 , the leakage current occurring between the first lamp  421  and the top side wall  412  and between the second lamp  422  and the bottom side wall  413  may decrease. Thus, the deterioration of the brightness near the top and bottom sidewalls  412  and  413  may be prevented, thereby improving the brightness uniformity of the backlight assembly  400 . 
     In addition, the second terminals G 1  and G 2  of the first and second lamps  421  and  422  may directly contact with the container  410  to be grounded through the container  410 . When the second terminals G 1  and G 2  of the first and second lamps  421  and  422  are so grounded through the container  410 , no additional ground wires or terminals to ground the second terminals G 1  and G 2  by way of PCB  440  are required on the PCB inverter board  440 . That is, since the ground terminal(s) may be omitted from the PCB inverter board  440 , the size of the PCB inverter board  440  may be reduced. 
     Although exemplary embodiments in accordance with the disclosure have been provided, it is understood that the present teachings should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art in light of the foregoing and within the spirit and scope of the present teachings.