Patent ID: 8449167

Claim:
A backlight unit comprising: a lower frame comprising an opening in its upper part; a light source arranged in the opening; a light guide plate arranged in the opening for guiding light from the light source; and an upper frame arranged above the lower frame and having a window capable of transmitting light from the light guide plate; the lower frame and the upper frame being engagingly fixable by a projection integrally arranged on a side surface of one of the frames, and a rib portion on a side surface of the respective other frame the rib portion defining a hole with which the projection can be engaged; wherein a lower portion of a side surface of the upper frame and an upper portion of a side surface of the lower frame are in contact with each other and a width of the hole is larger than a width of the corresponding projection, wherein the upper frame has a first side end portion on a first overall end of the side surface of the upper frame and a second side end portion on a second, opposite overall end of the side surface of the upper frame, and wherein the lower frame has a first side end portion on a first overall end of the side surface of the lower frame and a second side end portion on a second, opposite overall end of the side surface of the lower frame, and the unit is so arranged that if one side of the projection is made in contact with one side of the hole, then the first side end portion on the first overall end of the side surface of the upper frame is located approximately in the same plane with a first side end portion on the first overall end of the side surface of the lower frame, and the second side end portion on the second overall end of the side surface of the upper frame extends beyond the second side end portion on the second overall end of the side surface of the lower frame.