Patent ID: 8780297

Claim:
A backlight module being an edge type backlight module and used in a liquid crystal display device, wherein the liquid crystal display device has a display area having a display-area center line, and the backlight module has a light guide plate and a back board, wherein the back board is correspondingly overlapped with the display area, characterized in that: the backlight module further comprises a plurality of light-emitting diodes, wherein the light-emitting diodes face an incident surface of the light guide plate, and the light-emitting diodes with respect to the display-area center line have a position center, and according to pitches between the adjacent light-emitting diodes, the light-emitting diodes are divided into: a first light group, wherein the light-emitting diodes of the first light group are positioned relatively close to the position center, and the light-emitting diodes of the first light group maintain a first pitch therebetween; a third light group, wherein bright bin of the third light group is lower than bright bin of the first light group, and the light-emitting diodes of the third light group are positioned relatively away from the position center, and the light-emitting diodes of the third light group maintain a third pitch therebetween, wherein the third pitch is smaller than the first pitch; and a second light group, wherein bright bin of the second light group is between the bright bins of the first light group and the third light group, and the light-emitting diodes of the second light group are mounted between the first light group and the third light group, and the light-emitting diodes of the second light group maintain a second pitch therebetween, wherein the second pitch is between the first pitch and the third pitch, wherein the incident surface of the light guide plate has a plurality of concave surfaces or has a plurality of convex surfaces excluding being a jagged structural surface with a plurality of sharp edges, wherein each of the concave surfaces is flat and has a height being different from the height of the adjacent concave surfaces; the concave surfaces are corresponding to the light groups, respectively, and each of the concave surfaces is separated from the corresponding light group at a distance, wherein the distance from the light group with a higher bright bin to the corresponding concave surface is longer than the distance from the light group with a lower bright bin to the corresponding concave surface; each of the convex surfaces is flat and has a height being different from the height of the adjacent convex surfaces; the convex surfaces are corresponding to the light groups, respectively, and each of the convex surfaces is separated from the corresponding light group at a distance, wherein the distance from the light group with a higher bright bin to the corresponding convex surface is shorter than the distance from the light group with a lower bright bin to the corresponding convex surface.