Patent Publication Number: US-8988630-B2

Title: Back frame and backlight system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of displaying techniques, and in particular to a back frame of a flat panel display device and a backlight system. 
     2. The Related Arts 
     The state-of-the-art liquid crystal display device comprises a front bezel, a panel, and a backlight module, of which the backlight module comprises a back frame, a reflector plate, a light guide, and a lighting assembly. 
     Currently, a variety of display panels of different sizes are available in the market to meet different needs of general consumers. For example, in the field of television set, the sizes of liquid crystal panels include 31.5, 42, 46, 48, and 55 inches. Different back frame molds are provided for liquid crystal planes of different sizes. 
     Referring to  FIG. 1 ,  FIG. 1  is a schematic view showing a conventional back frame of liquid crystal display device. As shown in  FIG. 1 , the conventional back frame  10  is a unitary back frame, and it is often that a unitary back frame  10  is made with metal stamping or plastic injection molding. The unitary back frame  10  consumes much material and has a high material cost. Further, a large-sized back frame  10  requires large-sized stamping equipment, and the size of mold corresponding to such a back frame  10  is large and the structure complicated, making the expenditure of the back frame mold high. As a consequence, the conventional back frame is of a high cost. 
     SUMMARY OF THE INVENTION 
     The technical issue to be addressed by the present invention is to provide a back frame and a backlight system, which lower down material cost and mold cost, facilitate heat dissipation, allow the strength of the back frame to meet a desired requirement, and improve fixing of circuit board. 
     To address the above technical issue, the present invention adopts a technical solution that provides a back frame of flat panel display device, which comprises primary assembling pieces, secondary assembling pieces, and a bracing piece for fixing a circuit board; the primary assembling pieces have a number of at least two, at least one of the primary assembling pieces having an end forming a joint section, the at least two primary assembling pieces being joined through the corresponding joint sections, the secondary assembling pieces being connected to the primary assembling pieces through joining; at least one of the primary assembling pieces comprises a reinforcement structure formed on the joint section thereof; the at least two primary assembling pieces comprise a primary assembling piece that has a heat source arranged thereon, the primary assembling piece that has the heat source arranged thereon having a first heat transfer capability, the remaining one or more primary assembling pieces of the at least two primary assembling pieces that have no heat source arranged thereon having a second heat transfer capability, the first heat transfer capability being greater than the second heat transfer capability; the bracing piece comprises a bracing body, a first suspension section, a first bearing section, and a first resilient bent section, the bracing body being fixed to the primary assembling pieces or the secondary assembling pieces or both of the primary assembling pieces and the secondary assembling pieces, wherein available mounting points between the bracing piece and the primary assembling pieces or the secondary assembling pieces are of a number of at least two so that the bracing piece is selectively mounted to the back frame at different positions; and the first suspension section extends from the bracing body in a lengthwise direction of the bracing body, the first bearing section being spaced from the bracing body and extending from the first suspension section in a lengthwise direction of the first suspension section, the first resilient bent section being located between the first bearing section and the bracing body and being bent from the first suspension section in a lengthwise direction of the first suspension section, the first bearing section and the first resilient bent section resiliently clamping a first side edge of the circuit board. 
     According to a preferred embodiment of the present invention, the at least two primary assembling pieces comprises a first primary assembling piece and a second primary assembling piece. 
     According to a preferred embodiment of the present invention, the joint sections comprise recesses formed in a surface of the first primary assembling piece and having a shape corresponding to the end of the second primary assembling piece for receiving the end of the second primary assembling piece. 
     According to a preferred embodiment of the present invention, the first primary assembling piece forms a first through hole in a bottom thereof, a second through hole being formed in the second primary assembling piece at a corresponding position, the back frame comprising a fastener, the fastener extending through the first through hole and the second through hole to joint the first primary assembling piece and the second primary assembling piece. 
     According to a preferred embodiment of the present invention, the joint sections comprise recesses formed in the surface of the first primary assembling piece, the second primary assembling piece having an end having a surface forming protrusions at corresponding positions, the protrusions being receivable in the recesses to join the first primary assembling piece and the second primary assembling piece to each other. 
     According to a preferred embodiment of the present invention, each of the primary assembling pieces has a cross-section of the joint section that has a line-folded configuration in order to form the reinforcement structure, the line-folded configuration comprising at least two joined line segments, the reinforcement structures of the two primary assembling pieces being stacked in a recess-projection paired form. 
     According to a preferred embodiment of the present invention, each of the primary assembling pieces has a cross-section of the joint section that is an arc shape to form the reinforcement structure, the reinforcement structures of the two primary assembling pieces being stacked in a recess-projection paired form. 
     According to a preferred embodiment of the present invention, the primary assembling piece that has the heat source arranged thereon has a first strength, the remaining one or more primary assembling pieces of the at least two primary assembling pieces that have no heat source arranged thereon having a second strength, the second strength being greater than the first strength. 
     According to a preferred embodiment of the present invention, the primary assembling piece that has the first heat transfer capability and the first strength is an aluminum piece and the primary assembling pieces that have the second heat transfer capability and the second strength are galvanized steel pieces. 
     According to a preferred embodiment of the present invention, the bracing body forms at least two through holes that are spaced in the lengthwise direction of the bracing body, the secondary assembling piece being mountable to any one of the at least two through holes and the bracing body being fixed to the secondary assembling piece. 
     According to a preferred embodiment of the present invention, the bracing piece comprises at least two bracing members, wherein at least one of the bracing members is mountable to the primary assembling piece in a lengthwise of the primary assembling piece and the other one of the bracing members forms at least two through hole that are spaced in the lengthwise direction of the bracing piece, the primary assembling piece being mountable to any one of the at least two through holes. 
     According to a preferred embodiment of the present invention, the bracing piece further comprises a second suspension section, a second bearing section, and a second resilient bent section, the second suspension section being spaced from the first suspension section and extending from the bracing body in a lengthwise direction of the bracing body, the second bearing section being spaced from the bracing body and extending from the second suspension section in a lengthwise direction of the second suspension section, the second resilient bent section being located between the second bearing section and the bracing body and extending from the second suspension in a lengthwise direction of the second suspension section, the second bearing section and the second resilient bent section resiliently clamping the circuit board. 
     According to a preferred embodiment of the present invention, the two bracing members clamp different positions of a first side edge and a second side edge of the circuit board. 
     According to a preferred embodiment of the present invention, the bracing body is of a step-like configuration and bridges between two of the primary assembling pieces, or two of the secondary assembling pieces, or between the primary assembling piece and the secondary assembling piece. 
     According to a preferred embodiment of the present invention, the back frame comprises a third primary assembling piece and a fourth primary assembling piece; and the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, and the fourth primary assembling piece are straight linear and are joined in a leading end-to-tailing end manner to form a rectangular main frame structure enclosing the back frame. 
     According to a preferred embodiment of the present invention, the secondary assembling pieces comprise a first secondary assembling piece and a second secondary assembling piece, the first secondary assembling piece having two ends respectively joined to at least two primary assembling pieces of the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, and the fourth primary assembling piece, the second secondary assembling piece having two ends respectively joined to at least two primary assembling pieces of the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, and the fourth primary assembling piece. 
     According to a preferred embodiment of the present invention, the two ends of the first secondary assembling piece are respectively joined to the first primary assembling piece and the second primary assembling piece that are adjacent to each other and the two ends of the second secondary assembling piece are respectively joined to the third primary assembling piece and the fourth primary assembling piece that are adjacent to each other; or the two ends of the first secondary assembling piece are respectively joined to the first primary assembling piece and the third primary assembling piece that are opposite to each other and the two ends of the second secondary assembling piece are respectively joined to the first primary assembling piece and the third primary assembling piece that are opposite to each other, the second primary assembling piece, the fourth primary assembling piece, the first secondary assembling piece, and the second secondary assembling piece being arranged parallel to each other. 
     According to a preferred embodiment of the present invention, the back frame comprises at least one bracing piece, which is releasably fixed to one or more of the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, the fourth primary assembling piece, the first secondary assembling piece, and the second secondary assembling piece, the bracing piece forming a bump. 
     To address the above technical issue, the present invention adopts a technical solution that provides a backlight system, which comprises a light source, a light homogenization mechanism, and a back frame; and the back frame carries the light source and the light homogenization mechanism, the back frame being any back frame described above. 
     The efficacy of the present invention is that to be distinguished from the state of the art, the present invention provides a back frame and a backlight system that comprises at least two primary assembling pieces. The joint section of the primary assembling piece forms a reinforcement structure in order to improve the strength of joining. The primary assembling pieces use different thermally conductive materials. Further, a circuit board is mountable through a bracing piece so that a mold for back frame is made simple in structure, the expenditures of the back frame mold and the back frame are reduced, the strength of the back frame can meet a desired requirement, heat dissipation is facilitated, fixing of circuit board is improved, and the manufacturing cost of flat panel display device is reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a conventional back frame of liquid crystal display device; 
         FIG. 2  is a schematic view showing a flat panel display device according to a first embodiment of the present invention; 
         FIG. 3  is a schematic view showing a back frame of a flat panel display device according to a second embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of a first embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of a second embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 6  is a cross-sectional view of a third embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 7  is a cross-sectional view of a fourth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 8  is a cross-sectional view of a fifth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 9  is a cross-sectional view of a sixth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 10  is a cross-sectional view of a seventh embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 11  is a cross-sectional view of an eighth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 12  is a cross-sectional view of a ninth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 13  is a cross-sectional view of a tenth embodiment of a joint section of a primary assembling piece taken along line A-A′ of  FIG. 3 ; 
         FIG. 14  is a schematic view showing another structure of the reinforcement structure of the back frame shown in  FIG. 3 ; 
         FIG. 15  is a schematic view showing a back frame of a flat panel display device according to a third embodiment of the present invention; 
         FIG. 16  is a schematic view showing a back frame of a flat panel display device according to a fourth embodiment of the present invention; 
         FIG. 17  is a schematic view showing a joining structure of a flat panel display device according to a fifth embodiment of the present invention; 
         FIG. 18  is a schematic view showing a diagonally-arranged first secondary assembling piece mounted to a main frame structure of a flat panel display device according to a sixth embodiment of the present invention; 
         FIG. 19  is a schematic view showing a first secondary assembling piece and a second secondary assembling piece mounted to a main frame structure of a flat panel display device according to a seventh embodiment of the present invention; 
         FIG. 20  is a schematic view showing joint sections of a back frame of a flat panel display device according to an eighth embodiment of the present invention; 
         FIG. 21  is a cross-sectional view showing a first embodiment of joint section of  FIG. 20 ; 
         FIG. 22  is a schematic view showing a joining structure of a joint section of a back frame of a flat panel display device according to a ninth embodiment of the present invention; 
         FIG. 23  is a schematic view showing a joining structure of a joint section of a back frame of a flat panel display device according to a tenth embodiment of the present invention; 
         FIG. 24  is a schematic view showing a joining structure of a joint section of a back frame of a flat panel display device according to an eleventh embodiment of the present invention; 
         FIG. 25  is a schematic view showing a joint section of a back frame of a flat panel display device according to a twelfth embodiment of the present invention; 
         FIG. 26  is a schematic view showing a joint section of a back frame of a flat panel display device according to a thirteenth embodiment of the present invention; 
         FIG. 27  is a schematic view showing a back frame of a flat panel display device according to a fourteenth embodiment of the present invention; 
         FIG. 28  is a schematic view showing a flat panel display device according to a fifteenth embodiment of the present invention; 
         FIG. 29  is a schematic view showing a back frame of flat panel display device; 
         FIG. 30  is a flow chart showing a method for manufacturing a back frame of a flat panel display device according to a sixteenth of the present invention; 
         FIG. 31  is a schematic view showing a flat panel display device with a touch screen according to a seventeenth embodiment of the present invention; 
         FIG. 32  is a schematic view showing a stereoscopic display device according to an eighteenth embodiment of the present invention; 
         FIG. 33  is a schematic view showing a plasma display device according to a nineteenth embodiment of the present invention; 
         FIG. 34  is a schematic view showing a portion of a back frame of a flat panel display device according to a twentieth embodiment of the present invention; 
         FIG. 35  is an enlarged view showing a mounting site of a bracing member of a back frame and an assembling piece shown in  FIG. 34 ; 
         FIG. 36  is a cross-sectional view showing the mounting site of the bracing member of the back frame and the assembling piece shown in  FIG. 34 ; 
         FIG. 37  is an enlarged view showing a mounting site of another bracing member of the back frame and another assembling piece shown in  FIG. 34 ; 
         FIG. 38  is a cross-sectional view showing the mounting site of said another bracing member of the back frame and said another assembling piece shown in  FIG. 34 ; 
         FIG. 39  is an enlarged view showing a mounting site of two bracing members of a back frame shown in  FIG. 34 ; 
         FIG. 40  is a cross-sectional vie showing the mounting site of the two bracing members of the back frame shown in  FIG. 34 ; 
         FIG. 41  is a schematic view showing a portion of a back frame of a flat panel display device according to a twenty-first embodiment of the present invention; 
         FIG. 42  is a schematic view showing a portion of a back frame of a flat panel display device according to a twenty-second embodiment of the present invention; and 
         FIG. 43  is a cross-sectional view showing a bracing piece of the back frame of  FIG. 42  and a circuit board. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 2-3 ,  FIG. 2  is a schematic view showing a flat panel display device according to a first embodiment of the present invention and  FIG. 3  is a schematic view showing a back frame of a flat panel display device according to a second embodiment of the present invention. As shown in  FIG. 2 , the flat panel display device  20  according to the instant embodiment comprises: a backlight system  21  and a display panel  22 . The backlight system  21  is arranged on a back side of the display panel  22  and supplies light to the display panel  22 . 
     In the instant embodiment, the backlight system  21  comprises a light source  25 , a light homogenization mechanism  24 , and a back frame  23 . The back frame  23  carries the light source  25  and the light homogenization mechanism  24 . When the backlight system  21  is an edge lighting type, the light homogenization mechanism  24  is a light guide; and when the backlight system  21  is a direct type, the light homogenization mechanism  24  is a diffuser plate. The back frame  23  comprises at least a first primary assembling piece and a second primary assembling piece, and the two of at least first and second primary assembling pieces constitute a main frame structure  27  of the back frame  23 . 
     Referring also to  FIG. 3 , the back frame  23  of the first embodiment comprises a first primary assembling piece  261  and a second primary assembling piece  262 . The first primary assembling piece  261  has an end joined to an end of the second primary assembling piece  262 , and the first primary assembling piece  261  has another end joined to another end of the second primary assembling piece  262  in order to form the main frame structure  27  of the back frame  23 . The first primary assembling piece  261  and the second primary assembling piece  262  are both aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece  261  and the second primary assembling piece  262  are L-shaped. 
     Further referring to  FIG. 3 , in the instant embodiment, the first primary assembling piece  261  comprises a joint section  2611  and the second primary assembling piece  262  comprises a joint section  2612 . At least one of the first primary assembling piece  261  and the second primary assembling piece  262  comprises a reinforcement structure on the joint section thereof. In other words, the reinforcement structure is arranged on at least the joint section  2611  or the joint section  2612 . 
     An example that the joint section  2611  and the joint section  2612  are both provided with a reinforcement structure will be described. 
     The joint section  2611  and the joint section  2612  have a cross-section that has a line-folded configuration in order to form a reinforcement structure. The line-folded configuration comprises at least two joined line segments. For example, the line-folded configuration of the reinforcement structure may be a rectangle (as shown in  FIG. 4 , in which circled by phantom lines is a stacked recess-projection paired form), a trapezoidal (as shown in  FIG. 5 ), a swallow-tailed shape (as shown in  FIG. 6 ), an inverted T-shape (as shown in  FIG. 7 ), a conic shape (as shown in  FIG. 8 ), a wavy shape (as shown in  FIG. 9 ), a grating shape (as shown in  FIG. 10 ), or may alternatively be a T-shape, a cruciform shape, or a fork-like shape. The reinforcement structure of the joint section  2611  of the first primary assembling piece  261  and the reinforcement structure of the joint section  2621  of the second primary assembling piece  262  are stacked in a recess-projection paired form. 
     Alternatively, the joint section  2611  and the joint section  2621  may have a cross-section that is an arc shape to form the reinforcement structure. When the cross-section is an arc shape, the arc shape can be one or more groups of single curvature (as shown in  FIG. 11 ), dual curvatures (as shown in  FIG. 12 ) or multiple curvatures (as shown in  FIG. 13 ). The reinforcement structure of the joint section  2611  of the first primary assembling piece  261  and the reinforcement structure of the joint section  2621  of the second primary assembling piece  262  are stacked in a recess-projection paired form. 
     It is apparent that the shape of the cross-section that can be used to form a reinforcement structure is not limited to these and any can be used provided the strength of the reinforcement structure is improved. Further, it is noted that in all the embodiments of joint section of primary assembling piece shown in  FIGS. 5-13 , except  FIG. 5  showing the shapes of the reinforcement structure of the joint section  2611  and the reinforcement structure of the joint section  2621  and the recess-projection stacking between the two reinforcement structures, the remaining drawings show only the shape of the reinforcement structure of one of the joint section  2611  or  2612  and the recess-projection stacking is not illustrated. 
     Referring to  FIG. 14 , which is a schematic view showing another structure of the reinforcement structure provided on the joint section  2621 , the reinforcement structure comprises a plate layer  2623 . The plate layer  2623  functions to thicken the joint section  2621 , with the joint section  2611  being stacked on the joint section  2621 . 
     It is appreciated that the embodiments of the present invention employ a joining operation to form a back frame in order to simplify the structure of the back frame and save the material used for the back frame so as to reduce the manufacturing cost of a backlight display device. Meanwhile, through the arrangement of reinforcement structure on a joint section of a primary assembling piece, the strength of the joint site of the back frame can be improved to thereby ensure the overall strength of the back frame meets desired requirement. 
     It is noted all the embodiments of the reinforcement structure described above are also applicable to various embodiments of back frame, backlight system, and flat panel display device. 
     Referring also to  FIG. 15 , the back frame  23  of a second embodiment comprises a first primary assembling piece  281 , a second primary assembling piece  282 , and a third primary assembling piece  283 . The three primary assembling pieces  281 ,  282 , and  283  are assembled and joined to form a main frame structure  27  of the back frame  23 . The three primary assembling pieces  281 ,  282 , and  283  are all aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece  281  is L-shaped, and the second and third primary assembling pieces  282 ,  283  are straight linear. 
     Further, the back frame  23  further comprises secondary assembling pieces arranged inside and joined to the main frame structure  27 . 
     A detailed description will be given to the back frame  23  of the flat panel display device  20  according to the present invention, which comprises four primary assembling pieces and two secondary assembling pieces. 
     Referring to  FIG. 16 ,  FIG. 16  is a schematic view showing a back frame of flat panel display device according to a fourth embodiment of the present invention. As shown in  FIG. 16 , in the instant embodiment, a back frame  23  comprises: a first primary assembling piece  231 , a second primary assembling piece  232 , a third primary assembling piece  233 , a fourth primary assembling piece  234 , a first secondary assembling piece  235 , a second secondary assembling piece  236 , and bracing pieces  2371 ,  2372 ,  2373 ,  2374 ,  2375 ,  2376 , and  2377 . The first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234  are successively joined to each other in an end-to-end manner to constitute a rectangular main frame structure  27  of the back frame  23 . The first secondary assembling piece  235  and the second secondary assembling piece  236 , serving as ancillary assembling pieces, are arranged in the main frame structure  27  and joined to the main frame structure  27 . 
     Specifically, an end of the first primary assembling piece  231  is joined to an end of the second primary assembling piece  232 , another end of the second primary assembling piece  232  is joined to an end of the third primary assembling piece  233 , another end of the third primary assembling piece  233  is joined to an end of the fourth primary assembling piece  234 , and another end of the fourth primary assembling piece  234  is joined to another end of the first primary assembling piece  231  in order to form the rectangular main frame structure  27 . The first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234  are all aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234  are straight linear, yet in other embodiments, it is apparent to those skilled in the art to make all the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234  L-shaped, or some being straight linear and the remaining being L-shaped. For example, in  FIG. 3 , the first primary assembling piece  261  and the second primary assembling piece  262  are both L-shaped; in  FIG. 4 , the first primary assembling piece  281  is L-shaped, while the second and third primary assembling pieces  282  and  283  are straight linear. 
     In the instant embodiment, the back frame  23  of the flat panel display device  20  is formed by joining connection. As shown in  FIG. 17 , an illustrative example is given for the connection of an end of the first primary assembling piece  231  to an end of the second primary assembling piece  232 , wherein the end of the second primary assembling piece  232  is joined to the end of the first primary assembling piece  231  by means of for example screwing, fastening, or welding, to have the end of the second primary assembling piece  232  connected to the end of the first primary assembling piece  231 . 
     In the instant embodiment, the first secondary assembling piece  235  and the second secondary assembling piece  236  are arranged in the main frame structure  27  of the back frame  23 . An end of the first secondary assembling piece  235  is joined to the first primary assembling piece  231  and another end of the first secondary assembling piece  235  is joined to the third primary assembling piece  233 ; and an end of the second secondary assembling piece  236  is joined to the first primary assembling piece  231  and another end of the second secondary assembling piece  236  is joined to the third primary assembling piece  233 . Further, the second primary assembling piece  232 , the fourth primary assembling piece  234 , the first secondary assembling piece  235 , and the second secondary assembling piece  236  are arranged parallel to each other. In other embodiments, those skilled in the art may arrange at least one secondary assembling piece in the main frame structure  27 . For example, only the first secondary assembling piece  235  is arranged in the main frame structure  27 . Further, the two ends of the first secondary assembling piece  235  can be selectively joined to at least two of the primary assembling pieces of the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234 . For example, the first secondary assembling piece  235  is set diagonally in the main frame structure  27 , as shown in  FIG. 7 . Similarly, the two ends of the second secondary assembling piece  236  can be selectively joined to at least two of the primary assembling pieces of the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , and the fourth primary assembling piece  234 . For example, the two ends of the first secondary assembling piece  235  are respectively joined to the first primary assembling piece  231  and the second primary assembling piece  232  that are adjacent to each other and the two ends of the second secondary assembling piece  236  are respectively joined the third primary assembling piece  233  and the fourth primary assembling piece  234  that are adjacent to each other, as shown in  FIG. 19 . 
     In the instant embodiment, the back frame  23  comprises seven bracing pieces  2371 ,  2372 ,  2373 ,  2374 ,  2375 ,  2376 , and  2377 . The bracing piece  2371  is fixed to the fourth primary assembling piece  234 ; the bracing pieces  2372 ,  2373  are both fixed to the first secondary assembling piece  235 ; the bracing piece  2374  is fixed to the second secondary assembling piece  236 ; the bracing piece  2375  is fixed to the second primary assembling piece  232 ; and the bracing pieces  2376 ,  2377  are each fixed, at two ends thereof, to the first secondary assembling piece  235  and the second secondary assembling piece  236 . In practice, the bracing pieces can be fixed to one or more of the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , the fourth primary assembling piece  234 , the first secondary assembling piece  235 , and the second secondary assembling piece  236 . In other embodiments, those skilled in the art may mount bracing pieces of any other numbers to the back frame  23 , such as one or more bracing pieces. Further, the bracing pieces can be releasably fixed to one or more of the first primary assembling piece  231 , the second primary assembling piece  232 , the third primary assembling piece  233 , the fourth primary assembling piece  234 , the first secondary assembling piece  235 , and the second secondary assembling piece  236 . 
     The bracing pieces  2371 ,  2372 ,  2373 ,  2374 ,  2375 ,  2376 , and  2377  may be provided with bumps (not labeled) so that the back frame  23  may fix components, such as circuit boards, with such bumps. 
     Molds for making the back frame  23  will be described. In the instant embodiment, the first primary assembling piece  231  and the third primary assembling piece  233  are of the same size and shape so that they can be made by stamping with the same mold. The second primary assembling piece  232 , the fourth primary assembling piece  234 , the first secondary assembling piece  235 , and the second secondary assembling piece  236  are of the same size and shape so that they can be made by stamping with the same mold, making it possible to share the mold. Thus, the back frame  23  of the present invention can be made by stamping with only two small-sized molds, and compared to the conventional back frame  10  that requires a large-sized mold, the molds for making the back frame  23  of the present invention are simple in structure and small in size and thus the cost of mold for the back frame  23  can be lowered. Further, compared to the whole back frame structure of the conventional back frame  10 , the back frame  23  of the present invention can significantly save material used and thus reduce the manufacturing cost of the flat panel display device  20 . 
     Referring to  FIG. 20 ,  FIG. 20  is a schematic view showing joint sections of a back frame of a flat panel display device according to an eighth embodiment of the present invention. As shown in  FIG. 20 , in the instant embodiment, an end of the first primary assembling piece is provided with two joint sections, and the joint sections have a structure mating an end of the second primary assembling piece so that the first primary assembling piece can be joined to a corresponding end of the second primary assembling piece. 
     Specifically, the first primary assembling piece  231  has an end forming joint sections  2311 ,  2312 , and the joint sections  2311 ,  2312  are arranged in a spaced manner in a lengthwise direction of the first primary assembling piece  231 . The joint sections  2311 ,  2312  are formed by forming recesses having a shape mating an end of the second primary assembling piece  232  in the first primary assembling piece  231  in order to receive the end of the second primary assembling piece  232  therein. As shown in  FIG. 21 , the joint sections  2311 ,  2312  are recesses that do not extend through opposite surfaces of the end of the first primary assembling piece  231  and the recesses are of a rectangular shape with the second primary assembling piece  232  being straight linear. 
     To assemble a large-sized back frame  23 , the joint section  2311  that is close to the very end of the first primary assembling piece  231  is first taken and a second primary assembling piece  232  having a corresponding width is selected. Afterwards, an end of the second primary assembling piece  232  is positioned in the recess of the joint section  2311 . And then, means, such as screwing, fastening, or welding, is applied to join and fix the end of the second primary assembling piece  232  to the joint section  2311 . To assemble a small-sized back frame  23 , the joint section  2312  that is distant from the very end of the first primary assembling piece  231  is first chosen and a second primary assembling piece  232  having a corresponding width is selected. Afterwards, an end of the second primary assembling piece  232  is positioned in the recess of the joint section  2312 . And then, means, such as screwing, fastening, or welding, is applied to join and fix the end of the second primary assembling piece  232  to the joint section  2312 . Specifically, for example the second primary assembling piece  232  forms a protrusion at a corresponding location on a surface thereof, and the protrusion of the second primary assembling piece  232  is embedded in the recess the first primary assembling piece  231  at a corresponding location in order to join the first primary assembling piece  231  and the second primary assembling piece  232 , as shown in  FIG. 11 . Further, the second primary assembling piece  232  may form, on one end thereof, at least two protrusions that are spaced in the lengthwise direction of the second primary assembling piece  232 , such as two, three, or four protrusions. 
     Furthermore, the recess of the first primary assembling piece  231  can be a recess of a multi-stepped configuration and the second primary assembling piece  232  forms, at a corresponding location, a protrusion having a multi-stepped configuration corresponding to the recess, as shown in  FIG. 23 . Further, as shown in  FIG. 24 , taking the joint section  2311  as an example, the recess of the first primary assembling piece  231  forms, in a bottom thereof, a first through hole  2313 , and the second primary assembling piece  232  forms, at a location corresponding to the joint section  2311 , a second through hole  2321 . The back frame  23  further comprises a fastener  240 . The fastener  240  extends through the first through hole  2313  and the second through hole  2321  to joint the first primary assembling piece  231  and the second primary assembling piece  232  to each other. 
     As shown in  FIG. 25 , in another embodiment of the back frame of flat panel display device according to the present invention, the recesses of the joint sections  2311 ,  2312  of the first primary assembling piece  231  are of a circular shape. Yet, in other embodiments, those skilled in the art may arrange the shape of the recesses to be other polygonal configurations, such as triangle. 
     As shown in  FIG. 26 , in another embodiment of the back frame of flat panel display device according to the present invention, the joint sections  2311 ,  2312  are recesses that do not extend through opposite surfaces of the first primary assembling piece  231 , whereby an end of the second primary assembling piece  232  is movable within the joint sections  2311 ,  2312 . For example, after the end of the second primary assembling piece  232  is set extending beyond and joined and fixed to the joint section  2312 , the portion of extension is then trimmed off so that the length of the second primary assembling piece  232  that serves as a primary assembling piece of the back frame can be adjusted. 
     In a practical application, the other end of the first primary assembling piece  231  and both ends of the third primary assembling piece  233  are all provided with two joint sections having a structure identical to that of the joint sections  2311 ,  2312 . The ends of the second primary assembling piece  232  and the ends of the fourth primary assembling piece  234  may be subjected to specific designs or no design at all according to the application. For example: 
     (1) In a first situation, as shown in  FIG. 21 , the two ends of the second primary assembling piece  232  and the two ends of the fourth primary assembling piece  234  are of no specific design. In other words, the ends are of the same structure as the remaining portions. Under this condition, in making a join with a selected joint section  2311  ( 2312 ) at one end of the first primary assembling piece  231  (the same applicable to the other end), if an attempt is made to change the width of the back frame  23 , then the length of the corresponding second primary assembling piece  232  and fourth primary assembling piece  234  must be selected accordingly. Namely, if the joint section  2311  that is close to the very end of the first primary assembling piece  231  is selected for joining, then no trimming is applied to the second primary assembling piece  232  and the fourth primary assembling piece  234  or the portion that is trimmed off is short; if the joint section  2312  that is distant from the very end of the first primary assembling piece  231  is selected for joining, then the second primary assembling piece  232  and the fourth primary assembling piece  234  are trimmed and the trimmed portion being long or short is according to the distance that the joint section is from the very end of the first primary assembling piece  231  being great or small; and 
     (2) In a second situation, it is similar to the first situation, but as shown in  FIG. 22 , the second primary assembling piece  232  and the fourth primary assembling piece  234  use different protrusions to respectively mate the first primary assembling piece  231  and the third primary assembling piece  233  in order to realize change of width of the back frame  23 ; similarly, if a joint section  2312  other than the first joint section  2311  that is close to the very end of the first primary assembling piece  231  is selected for joining, then before or after joining, excessive portions of the second primary assembling piece  232  and the fourth primary assembling piece  234  may be trimmed off. 
     This also applicable to a main frame structure  27  of the back frame  23  that is formed by joining two L-shaped primary assembling pieces. 
     In summary, the present invention provides a back frame  23  having a first primary assembling piece that is provided with at least two joint sections. The number of the joint section can be selected according to the requirement of customers. In the instant embodiment, a description is given to an example comprising two joint sections  2311 ,  2312 . Thus, to prepare the molds for making the back frame  23 , only two sets of mold are needed, namely one mold for a first primary assembling piece and the other mold for a second primary assembling piece. The first primary assembling piece may be provided with a plurality of joint sections for joining operation in order to form various sizes for the back frame  23 . To assemble the back frame  23 , based on the desired size of the back frame  23 , the corresponding one of the joint sections is selected. With the joint section, the second primary assembling piece is joined to the joint section of the first primary assembling piece and the other joint section of the first primary assembling piece that is located outward of the joining location of the second primary assembling piece is trimmed off to obtain a desired size of the back frame  23 . Compared to the conventional technology that requires different back frame molds for making different sizes of back frame  10 , the back frame of the flat panel display device  23  according to the present invention requires only a mold for the first primary assembling piece and a mold for the second primary assembling piece  28  so that mold sharing among various sizes of product can be realized and the molds used are of simple structures, allowing of reduction of expenditure of the molds for back frames. 
     Referring to  FIGS. 27-28 , an example of four primary assembling pieces and two secondary assembling pieces will be given to describe the difference in material section for the primary assembling piece of the back frame  23  of the flat panel display device  20  according to the present invention having a heat source arranged thereon and the assembling piece having no heat source arranged thereon. 
     In the four primary assembling pieces and the two secondary assembling pieces, at least two primary assembling pieces comprise the primary assembling piece that has a heat source arranged thereon. The primary assembling piece that has the heat source arranged thereon has a first heat transfer capability. The remaining one or more primary assembling pieces of the at least two primary assembling pieces that have no heat source arranged thereon have a second heat transfer capability. The first heat transfer capability is greater than the second heat transfer capability. 
     The heat source can be a light-emitting diode (LED), a printed circuit board (PCB), or other electronic devices that generate heat. LED is taken an example here. A parameter that represents the heat transfer capability can be thermal conductivity. In other words, the primary assembling piece that has a heat source arranged thereon has a thermal conductivity that is greater than the thermal conductivity of the remaining one or more primary assembling pieces that have no heat source arranged thereon. 
     The primary assembling piece that has a heat source arranged thereon has a first strength. The remaining one or more primary assembling pieces of the at least two primary assembling pieces that have no heat source arranged thereon have a second strength. The second strength is greater than the first strength. 
     The primary assembling piece that has the first heat transfer capability and the first strength is an aluminum piece and the primary assembling pieces that have the second heat transfer capability and the second strength are galvanized steel pieces. Certainly, besides aluminum pieces, other pieces having a better capacity of heat dissipation can be copper pieces, magnesium alloys, or open aluminum alloy foams. Besides galvanized steel pieces, pieces having a better strength can be organic pieces or tinned iron piece. 
     An example of back frame that comprises four primary assembling pieces and two secondary assembling pieces will be given as follow. As shown in  FIGS. 27-28 , a first primary assembling piece  291 , a second primary assembling piece  292 , a third primary assembling piece  293 , a fourth primary assembling piece  294 , a first secondary assembling piece  295 , and a second secondary assembling piece  296  constitute a back frame. The primary assembling pieces that have a heat source  25  arranged thereon are the third primary assembling piece  293  and the fourth primary assembling piece  294 . The third primary assembling piece  293  and the fourth primary assembling piece  294  are made of aluminum pieces M 1 . The first primary assembling piece  291 , the second primary assembling piece  292 , the first secondary assembling piece  295 , and the second secondary assembling piece  296  that do no have a heat source  10125  arranged thereon are made of galvanized steel pieces M 2 . 
     Further, the primary assembling piece that has a heat source arranged thereon can be a stacked structure of a first layer and a second layer, of which the first layer is adjacent to the heat source and the first layer has a heat transfer capability that is greater than heat transfer capability of the second layer. 
     The first layer is adjacent to the heat source and the material of the first layer can be selected to have a heat transfer capability greater than the heat transfer capability of the material of the second layer. For example, the first layer is an aluminum piece, or a copper piece, or magnesium alloys, or open aluminum alloy foams, and the second layer is an organic piece or tinned iron. Certainly, the primary assembling piece that carries the heat source  10125  can be of a single layer having a material used to make the first layer mentioned above. 
     Aluminum pieces and copper pieces have better performance of heat dissipation and are advantageous in extending lifespan of product. Galvanized steel has worse performance of heat dissipation, but the price is relatively low and strength is better. In the cost of a back frame, the material cost takes the greatest percentage. If the whole back frame is made of a material that has a better performance of heat dissipation, such as aluminum, then the cost is extremely high and the structural strength is poor. If it is completely made of a material having poor performance of heat dissipation, such as galvanized steel, then the heat dissipation will be poor and the product performance will be deteriorated. Thus, in practical applications, different materials must be used in manufacturing for different positions, such as a combination of aluminum piece and galvanized steel pieces, in order to minimize the product cost and at the same time ensure the requirements of heat dissipation and strength are satisfied, so that the material cost can be reduced and the product cost is lowered. Certainly, the above embodiments of different material selection for the primary assembling pieces are also applicable to a main frame structure that is formed by joining two L-shaped primary assembling pieces. 
     The present invention also provides a mold for making a back frame of flat panel display device. The back frame mold is provided with a main pattern for forming a primary assembling piece of the back frame and the main pattern comprises a sub-pattern that forms at least two joint sections on an end of the primary assembling piece. The primary assembling piece comprises the previously discussed first primary assembling piece and second primary assembling piece, corresponding to the above mentioned main pattern; and the joint section comprises the previously discussed joint section of the first primary assembling piece, corresponding to the above mentioned sub-pattern. Repeated description is omitted herein. 
     Referring to  FIG. 29 , a schematic view showing a back frame of flat panel display device according to the present invention is shown, a first primary assembling piece  261  and a second primary assembling piece  262 . The first primary assembling piece  261  has an end joined to an end of the second primary assembling piece  262 , and the first primary assembling piece  261  has another end joined to another end of the second primary assembling piece  262  in order to form the main frame structure  27  of the back frame  23 . The first primary assembling piece  261  and the second primary assembling piece  262  are both aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece  261  and the second primary assembling piece  262  are L-shaped. 
     Referring to  FIG. 3 , the first primary assembling piece  261  comprises a joint section  2611  and the second primary assembling piece  262  comprises a joint section  2612 . At least one of the first primary assembling piece  261  and the second primary assembling piece  262  comprises a reinforcement structure (not shown) on the joint section thereof. In other words, the reinforcement structure is arranged on at least the joint section  2611  or the joint section  2612 . 
     Referring to  FIG. 34 , a bracing piece  60  is formed by joining bracing members  601 ,  602 . Two ends of the bracing piece  60  are respectively fixed to assembling pieces  61 ,  62 . The assembling pieces  61 ,  62  are mountable to the bracing piece  60  in at least two different positions in the lengthwise direction of the bracing piece  60 , wherein the assembling pieces  61 ,  62  can be the primary assembling pieces or the secondary assembling pieces of each of the above embodiments. In other words, the bracing piece  60  can be mounted to the primary assembling pieces or the secondary assembling pieces, or can be mounted to both the primary assembling pieces and the secondary assembling pieces, wherein available mounting points between the bracing piece  60  and the primary assembling pieces or the secondary assembling pieces are of a number of at least two (corresponding to the previously mentioned two different positions), so that the bracing piece  60  can be mounted to different positions in the back frame. In other backup embodiments, the bracing piece  60  may has only one end fixed to the assembling piece, while the other end is arranged in a suspending form. The bracing piece  60  may also be of a unitary design. 
     Referring to  FIG. 42 , the bracing piece  60  comprises a bracing body  11161 , a first suspension section  11162 , a first bearing section  11163 , and a first resilient bent section  11164 . In other words, the bracing body  11161  is mounted to the primary assembling pieces or the secondary assembling pieces, or is mounted to both the primary assembling pieces and the secondary assembling pieces, wherein available mounting points between the bracing body  11161  and the primary assembling pieces or the secondary assembling pieces are of a number of at least two so that the bracing body can be mounted to different positions in the back frame. In the instant embodiment, the bracing body  11161  is of a step-like configuration and bridges between two assembling pieces  11171 ,  11172 . 
     The present invention also provides a mold for making a back frame of flat panel display device. The back frame mold is provided with a main pattern for forming a primary assembling piece of the back frame and the main pattern comprises a sub-pattern that forms at least two joint sections on an end of the primary assembling piece. The primary assembling piece comprises the previously discussed first primary assembling piece and second primary assembling piece, corresponding to the above mentioned main pattern; and the joint section comprises the previously discussed joint section of the first primary assembling piece, corresponding to the above mentioned sub-pattern. Repeated description is omitted herein. 
     Referring to  FIG. 30 , the present invention also provides a method for making a back frame of flat panel display device. The method comprises the following steps: 
     Step  501 : manufacturing at least two primary assembling pieces, the at least two primary assembling pieces comprising a primary assembling piece that carries a heat source. The primary assembling piece that carries the heat source has a first heat transfer capability, and the remaining one or more primary assembling pieces of the at least two primary assembling pieces that carry no heat source have a second heat transfer capability, the first heat transfer capability being greater than the second heat transfer capability; and 
     Step  502 : joining the at least two primary assembling pieces. 
     In the instant embodiment, when other joint sections are present between the joining location of the second primary assembling piece and the end of the first primary assembling piece, before or after the step of selecting one joint section of the at least two joint sections according to a size of the back frame to join the corresponding end of the second primary assembling piece, the other joint sections of the first primary assembling piece that are located outward of the joining position of the second primary assembling piece are trimmed off. The first primary assembling piece comprises the previously discussed first primary assembling piece, and the second primary assembling piece comprises the previously discussed second primary assembling piece, and repeated description will be omitted herein. 
     As shown in  FIG. 22 , the flat panel display device  20  of the present invention further comprises a touch screen  29 . The touch screen  29  is arranged on a light exit surface of the display panel  22  of the flat panel display device  20 . The flat panel display device  20  comprises: the backlight system  21  and the above discussed display panel  22 . The backlight system  21  is arranged at the back side of the display panel  22  and supplies light to the display panel  22 . 
     The backlight system  21  comprises a light source  25 , a light homogenization mechanism  24 , and a back frame  23 . The back frame  23  carries the light source  25  and the light homogenization mechanism  24 . When the backlight system  21  is an edge lighting type, the light homogenization mechanism  24  is a light guide; and when the backlight system  21  is a direct type, the light homogenization mechanism  24  is a diffuser plate. The back frame  23  comprises at least a first primary assembling piece and a second primary assembling piece, and the at least one first and second primary assembling pieces constitute a main frame structure  27  of the back frame  23 . 
     It is apparent that the backlight system  21  can be of a structure of any one of the previously discussed embodiments of the backlight system. 
     It is noted that the flat panel display device  20  of the present invention can be a liquid crystal display device or a liquid crystal television. 
     The present invention also provides a stereoscopic display device  30 . As shown in  FIG. 32 , the stereoscopic display device  30  comprises a liquid crystal lens grating  31 , a backlight system  32 , and a display panel  33 . The liquid crystal lens grating  31  is arranged on a light exit surface of the display panel  33 . The backlight system  32  can be a backlight system of any one of the above discussed embodiments, such as the backlight system  32  comprising the back frame  23 . The back frame  23  comprises at least first primary assembling piece and the second primary assembling piece. The at least first and second primary assembling pieces form a main frame structure of the back frame. The backlight system  32  can be of a structure of any of the previously discussed embodiments of backlight system and repeated description will be omitted herein. 
     The present invention also provides a plasma display device  40 . As shown in  FIG. 33 , the plasma display device  40  comprises a plasma display panel  41  and a back frame  42 . The back frame  42  is arranged at a back side of the display panel  41 . The back frame  42  can be the back frame of any one of the previously discussed embodiments and repeated description will be omitted herein. 
     The present invention also provides a bracing piece that is applicable to the back frame of each of the above disclosed embodiments, wherein the bracing piece is fixed to the assembling pieces and the assembling pieces are mountable to at least two different positions of the bracing piece in a lengthwise direction of the bracing piece, whereby the bracing piece is movable to make positions of bumps that are provided on the bracing piece for positioning purposes adjustable in order to meet the needs for different assembling requirements of the back frame. 
     Specifically, as shown in  FIG. 34 , in the instant embodiment, the bracing piece  60  is formed by joining bracing members  601 ,  602 . Two ends of the bracing piece  60  are respectively fixed to assembling pieces  61 ,  62 . The assembling pieces  61 ,  62  are mountable to the bracing piece  60  in at least two different positions in the lengthwise direction of the bracing piece  60 , wherein the assembling pieces  61 ,  62  can be the primary assembling pieces or the secondary assembling pieces of each of the above embodiments. In other backup embodiments, the bracing piece  60  may has only one end fixed to the assembling piece, while the other end is arranged in a suspending form. The bracing piece  60  may also be of a unitary design. 
     Further, referring in combination to  FIGS. 35-36 , formed in an end of the bracing member  601  that is fixed to the assembling piece  61  is an elongate through hole  6011  that is arranged in the bracing member  601  in the lengthwise direction of the bracing piece  60 . The bracing member  601  is fixed by a screw  63  to the assembling piece  61  of the back frame. The screw  63  is positionable in different locations within the elongate through hole  6011 . Thus, in assembling, the elongate through hole  6011  is put to overlap a threaded hole  611  of the assembling piece  61  and according to the need for mounting, the position of the bracing member  601  on the assembling piece  61  is adjusted in the lengthwise direction of the bracing piece  60  so as to adjust the position of the bump  6012  of the bracing member  601  with respect to the assembling piece  61 . After the bump  6012  of the bracing member  601  has been adjusted to a desired position, the screw  63  is set in a corresponding position within the elongate through hole  6011  and engages the threaded hole  611  of the assembling pieces  61  to thereby fix the bracing member  601  to the assembling piece  61 . 
     Similarly, referring in combination to  FIGS. 37-38 , in an end of the bracing member  602  that is fixed to the assembling piece  62 , an elongate through hole  6021  is formed in the lengthwise direction of the bracing piece  60 . A screw  64  is positionable in different positions within the elongate through hole  6021 , whereby by having the screw  64  engaging a threaded hole  621  of the assembling piece  62 , the bracing member  602  is fixed to the assembling piece  62 , so as to realize position adjustment of a bump  6022  with respect to the assembling piece  62 . 
     Further referring in combination to  FIGS. 39-40 , in ends of the bracing member  601  and the bracing member  602  that are fixed to each other, an elongate through hole  6013  is formed in the bracing member  601  in the lengthwise direction of the bracing piece  60 , and an the elongate through hole  6023  is formed in the bracing member  602  in the lengthwise direction of the bracing piece  60 . The bracing member  601  is fixed by a screw  65  to the bracing member  602 . The screw  65  can be set at any position within the elongate through holes  6013 ,  6023 . In assembling, the elongate through holes  6013 ,  6023  are set to overlap each other and the positions of the bracing members  601  and  602  in the lengthwise direction of the bracing piece  60  are adjusted according to the needs for mounting so as to adjust the positions of bumps  6012 ,  6022  with respect to the assembling pieces  61 ,  62  (see  FIG. 42 ) and the length of the bracing piece  60 . After the adjustment of position, the screw  65  is set to a corresponding position between the elongate through holes  6013  and  6023  and screwing is carried out to fix the bracing member  601  to the bracing member  602 . In other backup embodiments, the screws  63 ,  64 ,  65  can be replaced by other fasteners, such as rivets and bolts. 
     As shown in  FIG. 41 , in the instant embodiment, the bracing piece forms at least two through holes that are spaced in the lengthwise direction of the bracing piece to replace the elongate through hole of the above embodiments. Specifically, in the end of the bracing member  701  that is fixed to the assembling piece  71 , a plurality of through holes  7014 ,  7015 ,  7016  is arranged in the lengthwise direction of the bracing piece  70 . A screw (not shown) can be set in one of the through holes  7014 ,  7015 ,  7016  and engages a threaded hole  711  defined in the assembling piece  71  so as to fix the bracing member  701  to the assembling piece  71 , thereby realizing position adjustment of a bump  7012  with respect to the assembling piece  71 . 
     Similarly, in an end of the bracing member  702  that is fixed to the assembling piece  72 , a plurality of through holes  7024 ,  7025 ,  7026  is arranged in the lengthwise direction of the bracing piece  70 . A screw (not shown) can be set in one of the through holes  7024 ,  7025 ,  7026  and engages a threaded hole  721  defined in the assembling piece  72  so as to fix the bracing member  702  to the assembling piece  72 , thereby realizing position adjustment of a bump  7022  with respect to the assembling piece  72 . 
     Further, in ends of the bracing member  701  and the bracing member  702  that are fixed to each other, a plurality of through holes  7017 ,  7018 ,  7019  is arranged in the bracing member  701  in the lengthwise direction of the bracing piece  70  and a plurality of through holes  7027 ,  7028 ,  7029  is arranged in the bracing member  702  in the lengthwise direction of the bracing piece  70 . A screw (not shown) can be set in any of the plurality of through holes  7017 ,  7018 ,  7019  and any one of the plurality of through holes  7027 ,  7028 ,  7029 . In assembling, the positions of the bracing members  701  and  702  in the lengthwise direction of the bracing piece are adjusted according to the needs for mounting and corresponding ones of the through holes are set to overlap each other so as to adjust the positions of bumps  7012 ,  7022  with respect to the assembling pieces  71 ,  72  and the length of the bracing piece  70 . After the position adjustment, a screw is set to the overlapped position of corresponding through holes to carry out screwing so as to fix the bracing member  701  to the bracing member  702 . 
     In the above embodiments, the bracing piece is fixed by screws to the assembling pieces, but those having ordinary skills in the art may easily contemplate that fasteners, such as rivets, can be used for fixing. The present invention imposes no specific limitation in this respect. 
     The present invention also provides a bracing piece that is applicable to each of the above described embodiments and that is mounted to assembling pieces to fix a circuit board. Referring to  FIGS. 42-43 , assembling pieces  11171 ,  11172  are the various assembling pieces described in the above discussed embodiments, including the primary assembling pieces that are joined to form a main frame structure of a back frame or the secondary assembling pieces that are arranged inside the main frame structure and joined to the main frame structure. A bracing piece  60  comprises a bracing body  11161 , a first suspension section  11162 , a first bearing section  11163 , and a first resilient bent section  11164 . The bracing body  11161  is fixed to the assembling pieces  11171  and  11172 . In the instant embodiment, the bracing body  11161  is of a step-like configuration and bridges between the two assembling pieces  11171 ,  11172 . However, in backup embodiments of the present invention, the bracing body  11161  can be of a straight bar like configuration or other shapes. Further, the bracing body  11161  can be fixed to the assembling piece with only one end thereof, while the other end is arranged in a suspending form to simplify mounting process. 
     The first suspension section  11162  extends from the bracing body  11161  in a lengthwise direction of the bracing body  11161 . The first bearing section  11163  is spaced from the bracing body  11161  and extends from the first suspension section  11162  in a lengthwise direction of the first suspension section  11162 . The first resilient bent section  11164  is located between the first bearing section  11162  and the bracing body  11161  and is bent from the first suspension section  11163  in a lengthwise direction of the first suspension section  11162 . The first bearing section  11163  and the first resilient bent section  11164  resiliently clamp a first side edge of a circuit board  80 . 
     Referring to  FIG. 43 , the bracing piece  11160  further comprises a second suspension section  11162 ′, a second bearing section  11163 ′, and a second resilient bent section  11164 ′. The second suspension section  11162 ′ is spaced from the first suspension section  11162  and extends from the bracing body  11161  in a sideway direction of the bracing body  11161 . The second bearing section  11163 ′ is spaced from the bracing body  11161  and extends from the second suspension section  11162 ′ in a lengthwise direction of the second suspension section  11162 ′. The second resilient bent section  11164 ′ is located between the second bearing section  11163 ′ and the bracing body  11161  and the bracing body  11161  and is bent from the second suspension section  11162 ′ in a lengthwise direction of the second suspension section  11162 ′. The second bearing section  11163 ′ and the second resilient bent section  11164 ′ resiliently clamp a second side edge of the circuit board  80  that is opposite to the first side edge. In a preferred embodiment, the first suspension section  11162 , the first bearing section  11163 , and the first resilient bent section  11164  and the second suspension section  11162 ′, the second bearing section  11163 ′, and the second resilient bent section  11164 ′ are symmetric with respect to a center line of the bracing body  11161 . In a backup embodiment of the present invention, the bracing body  11161  of the bracing piece  11160  may comprise only the first suspension section  11162 , the first bearing section  11163 , and the first resilient bent section  11164  for only resiliently clamping the first side edge of the circuit board  11180 , and an additional bracing piece that is identical to the bracing piece  11160  is provided to resiliently clamp the second side edge of the circuit board  11180 . 
     Referring to  FIG. 43 , after the circuit board  11180  is mounted, an electromagnetic shielding piece  100  is set on the bracing body  11161 . The electromagnetic shielding piece  100  is spaced from the circuit board  11180  to shield electromagnetic signals generated by the circuit board  11180 . The electromagnetic shielding piece  100  can be a Faraday cage or a metal plate. 
     Referring to  FIG. 42 , in the instant embodiment, a bracing piece  90  that is identical in structure to the bracing piece  60  is further provided. The bracing piece  90  is spaced from the bracing piece  60  to clamp different locations of the first and second side edges of the circuit board  11180 . 
     With the above discussed manners, the present invention provides a back frame and a backlight system, which form a back frame through joining operations so that a back frame has a simple structure, the material used for the back frame is saved, and the manufacturing cost of a backlighting display device is reduced. Further, with a bracing piece that comprises a bracing body, a first suspension section, a first bearing section, and a first resilient bent section arranged to fix a circuit board, the expenditure of back frame mold is reduced and the problem that a circuit board cannot be easily fixed is overcome. 
     With the above discussed manners, the present invention provides a flat panel display device, a stereoscopic display device, and a plasma display device that have a mold for back frame that is of a simple structure, reduce material cost and mold cost, facilitate heat dissipation, facilitate retention of back frame, is easy to use, and facilitate fixing a circuit board. 
     Embodiments of the present invention have been described, but are not intending to impose any undue constraint to the appended claims of the present invention. Any modification of equivalent structure or equivalent process made according to the disclosure and drawings of the present invention, or any application thereof, directly or indirectly, to other related fields of technique, is considered encompassed in the scope of protection defined by the claims of the present invention.