A platelet collection device comprising a centrifugal spin-separator container with a cavity having a longitudinal inner surface. The brightness enhancement film includes a light transmissive substrate, a plurality of prism rods, and at least one light diffusion structure. A processor brings a detection start register into a set state and causes the picture top detector to execute the picture top detection processing during an overflow of an output buffer, and executes an interruption processing of rewriting, as a value of a write address register, an address where a top of an overflow picture to be a picture causing the overflow is stored.