US Patent 8070346 Illumination device and liquid crystal display device

An illumination device which can be used as a front light or a back light by improving brightness unevenness in the vicinity of an LED without dropping entire brightness and a liquid crystal display device using the same. This illumination device 10 has a light source on a light entering face 27 of a light guide plate 20 and a light guide plate 20 in which prisms 25 for reflecting by polarization or emitting light out of the light guide plate 20 are formed on a light emission face or a light reflecting face thereof and a cylindrical lens 26 for orienting and magnifying light is formed on the other face.