Patent attributes
An increased emission brightness provides a clear image display. Light from luminescent lamp 10 travels into light guide plate 2 through incidence face 3, being emitted from emission face 4 for irradiating LCD panel 5. Back face 7 of light guide plate 2 serves as light gathering function surfaces 14, 15 reflecting light as to gather the light around a normal direction of emission face 4 which provides an emission promotion surface having first and second slopes 17 and 18 for promoting the light introduce through incidence face 3, the first slopes 17 being configurated as to gently decrease thickness of light guide plate 2 with an increasing distance from incidence face 3 while second slopes 18 are configurated as to sharply increase thickness of light guide plate 2 with an increasing distance from thinner-plate-thickness-side end portions of slopes 17.
