Back frame and backlight system of flat panel display device

A back frame of a flat panel display device, wherein the back frame comprises at least two assembling pieces, the at least two assembling pieces being joined to form the back frame, the back frame further comprising a bracing piece, the bracing piece being set in pawl mating engagement with the assembling pieces;

• wherein the back frame comprises at least two primary assembling pieces, the at least two primary assembling pieces being joined to form a main frame structure of the back frame, the at least two primary assembling pieces comprising a first primary assembling piece and a second primary assembling piece, the first primary assembling piece having an end forming at least two joint sections, each of the joint sections having a structure mating an end of the second primary assembling piece, the first primary assembling piece using one of the joint sections to join the corresponding end of the second primary assembling piece;
• wherein the at least two joint sections are arranged to space from each other in a lengthwise direction of the first primary assembling piece;
• wherein the joint sections comprise recesses formed in a surface of the first primary assembling piece, the second primary assembling piece 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;
• and
• wherein the second primary assembling piece has an end having a surface forming at least two protrusions that are arranged to space from each other in a lengthwise direction of the second primary assembling piece.