US Patent 7198384 Light emitting device

A fluorescent structure is provided on a curved recess plane of a reflector. The fluorescent structure has a shape of a cylinder which is cut by a plane including its central axis and along its longitudinal direction. An inner wall of the fluorescent structure tapers in like a cone from both ends to the central portion of the fluorescent structure. The structure includes a fluorescent material, for example YAG, which converts blue light to white light and diffuses the white light. Blue LEDs are provided close to both ends of the structure. The blue LEDs are positioned such that blue light emitted from the blue LED enters from both ends and is led to the central portion.