A backlight module has two lighting sides installed inside a casing. Two
sides of the casing are installed with a main display screen and a
sub-display screen. The backlight module comprises at least one light
source; a light guile plate for guiding light from the light source to
the main display screen and the sub-display screen. A lower diffusion
sheet, a first light enhancing sheet and preferably, an upper diffusion
sheet are installed between the main display screen and the light guide
plate. A reflective sheet, a second light enhancing sheet and preferably,
an upper diffusion sheet are installed between the sub-display screen and
the light guide plate. Part of light from the sub-display screen is
reflected to the main display screen.