Optimization of a Photographic Shutter by Minimization of Closing Time Variability

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Daniels, Steven D
thesis / dissertation description
A photographic shutter was considered, comprised of a mechanically driven, pivoted opening blade and a spring driven, pivoted closing blade which is released by a magnetic holding coil through an armature lever. The magnitude of the viscous drag of air on the closing blade is approximated, and its effect on the travel time (lag time) of the blade is determined to be insignificant. A set of equations is derived representing the dynamic performance of the combination of the closing blade and the armature lever. These equations are used to develop a mathematical representation of the variation in lag time due to manufacturing tolerances of the parts involved. Then an optimization computer program is devised and utilized which uses an "exhaustive" search technique to locate the minimum for the variation in lag time as a function of five independent variables. A previously written "gradient based" optimization computer program is also employed to minimize variation in lag time. The exhaustive program yields a reduction in variation of lag time of 6 percent while the gradient based program yields a reduction of 2 percent.