Photoflash lamp with optical element undergoing heat generated change from substantially uniform thickness to being thicker in the center, during flash ignition, to enhance light output by converging light rays

摘要

A photoflash lamp comprising a lamp housing, a combustible material burning inside the lamp housing to produce a flash illumination, and ignition means for igniting the combustible material, is characterized by optical element means on the lamp housing for changing from a substantially uniform thickness to being thicker in a center than at an edge, responsive to the lamp housing becoming heated when the combustible material is burned inside the lamp housing to produce the flash illumination. The optical element, when changed from a substantially uniform thickness to being thicker in the center than at the edge, forms a positive lens that converges the light rays during flash illumination to enhance the light output.