| 摘要 |
An effective radiation region of a rod-type light source 8 having circumferences of electrodes 8A and 8B has a length AR. A light diffusible surface 10D (or 10D') is formed on the rear surface (or emitting surface) of a light guide plate 10 to which a light is supplied from the rod-type light source 8. The light diffusible surface 10D (10D') has an emission quantity suppressing region AR1, emission quantity promoting region AR2 and light quantity control region AR3. The emission quantity suppressing region AR1 is formed in the vicinity of an incidence surface of the light guide plate 10 so as to have a dimension nearly equal to AR. The emission quantity promoting region AR2 is formed in the vicinities of both the ends of the emission quantity suppressing region AR1. The emission quantity promoting region AR2 is formed so as to have light scattering power which is increased locally near the incidence surface. The light quantity control region AR3 is formed so that light scattering power is increased gradually according to a distance from the incidence surface. The emission quantity suppressing region AR1 prevents excessive light emission, and the emission quantity promoting region AR2 supplements insufficient light emission in the circumferences of the electrodes 8A and 8B.
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