SURFACE LIGHT SOURCE APPARATUS

摘要

PURPOSE:To enable uniform distribution of light with good luminous efficiency and reduction of the thickness of a discharge tube by applying phosphor for converting ultraviolet ray radiated from the discharge tube into visible light on a surface light emission part having a desired shape. CONSTITUTION:Discharge tubes 1 for radiating ultraviolet rays are disposed on both ends and phosphor 2 for converting the ultraviolet rays into visible light is applied on the inside of a diffusion board 3 serving as a surface light emission part having a desired shape. A reflection member 4 is provided on the opposite side of the diffusion board 3. The ultraviolet rays radiated from the discharge tube 1 reach the phosphor 2 directly or through reflections on the member 4 to be converted into visible light. The converted light is diffused by the diffusion board 3 and leaves from a light emission surface. Thus, since the phosphor 2 is applied on the surface light emission part so as to convert the ultraviolet rays into visible light without applying it on the discharge tube 1, good luminous efficiency and uniform brightness distribution are attained to enable the uniform distribution of light and the improvement in the luminous efficiency enables reluction the thickness of the discharge tube.