1. Field of Invention
The present invention relates to a combined frame and a back light module. More particularly, the present invention relates to a combined frame capable of fastening the power cord of a lamp and preventing the solder joints joining the power cord and the lamp from loosening up and a back light module deploying the combined frame.
2. Description of Related Art
Thanks to the many breakthroughs in semiconductor technologies and the introduction advanced display devices, multi-media have been developed at an exceedingly fast pace. In the past, cathode ray tube (CRT) was almost the only commercially available display device due to its superb quality and low price. However, with the advent of personal computers, other factors related to a display device such as spatial occupation, power consumption and environmental safety become important considering factors. Because CRT is basically a bulky and power gusting device, it has been gradually replaced by radiation free, high image quality, slim and power efficient displays such as liquid crystal displays (LCD).
FIG. 1 is a diagram showing the structural layout of a conventional back light module. As shown in FIG. 1, the back light module 100 comprises light-guiding plate (LGP) 110, a lamp 120, a reflector 130, an optical film 140 and a combined plastic frame 200. The light-guiding plate 110 furthermore comprises a light-incidenting surface 112, a light-diffusing surface 114 and a light-emitting surface 116. The lamp 120 is set up next to the light-incidenting surface 112 of the light-guiding plate 110. Light from the lamp 120 enters the light incidenting surface 112 of the light-guiding plate 110 to be diffused and reflected by the light-diffusing surface 114. Finally, the diffused and reflected light leaves the light-guiding plate 110 through the light-emitting surface 116. In other words, the light-guiding plate 110 is capable of transforming linear light rays from the lamp 120 into a planar light source for illuminating the entire surface of a liquid crystal panel (not shown) uniformly.
The reflector 130 is positioned on one side enclosing the lamp 120 so that light emitted from the lamp 120 is concentrated towards the light-incidenting surface 112 of the light-guiding plate 110. The optical film 140 is positioned above the light-emitting surface 116 of the light-guiding plate 110 for increasing luminance of the back light module 100.
The combined frame 200 comprises of an upper frame 210 and a lower frame 220. The lower frame 220 supports the light-guiding plate 110, the lamp 120 and the reflector 130. The sidewall 222 of the lower frame 220 furthermore comprises a plurality of protrusions 224. The upper frame 210 has a plurality of fasteners 212 that corresponds in position to the protrusions 224. Each fastener 212 has an opening 214 suitable for fastening with a protrusion 224 so that the upper frame 210 and the lower frame 220 are tightly engaged together. In addition, the upper frame 210 has a window 216 for exposing the light emitted from the light-emitting surface 116 of the light-guiding plate 110 so that a liquid crystal panel (not shown) above the upper frame 210 is illuminated by a planar light source. In brief, through the engagement of the upper frame 210 and the lower frame 220, the light-guiding plate 110, the lamp 120 and the reflector 130 are bound together into an integrative back light module 100.
FIGS. 2A and 2B are diagrams showing the outlet end of a lamp-linked power cord in a conventional back light module. As shown in FIGS. 2A and 2B, one end of the lamp 120 resting on the lower frame 220 is often soldered to a power cord 122. The power cord 122 emerging from the back light module 100 is usually connected to a bias voltage so that the lamp 120 is powered. Furthermore, a stationing block 226 having a cable groove 228 is attached to one side of the lower frame 220. The power cord 122 is buried inside the cable groove 228 so that the other end of the power cord 122 is exposed outside the lower frame 220. In addition, the upper frame 210 also has a cover plate 218 that covers the stationing block 226 when the upper frame 210 and the lower frame 220 are fastened together through the fasteners 212 and the protrusions 224.
Since the cable groove 228 in a conventional stationing block 226 has a straight design, the following defects are produced: 1. With a straight cable groove design, the power cord inside the cable groove is free to slide in the axial direction of the lamp and often leads to a shift in the power cord position. 2. With a straight cable groove design, the power cord inside the cable groove is often subjected to unintended jerking forces while the module is being assembled or tested. Consequently, the soldering points may loosen up or be exposed resulting in current leakage. If the power cord is pulled too hard, the solder joint may break apart leading to lamp failure.