Blade type focal plane shutter with improved arm construction

摘要

A blade type focal plane shutter is designed to decrease the shutter charge energy and to improve the durability of the shutter without decreasing the impact resistance of the main arms of the shutter. The shutter may comprise a shutter base plate having an aperture; shutter blades each composed of a plural number of blade segments and a driving mechanism having main arms and follower arms rotatably connected to the shutter base plate and blade segments as to form a parallel link mechanism, the main arms having pin-receiving holes in which driving pins are engaged respectively. Through the driving pins, the driving mechanism is able to move the blade segments between the aperture opening position in which the blade segments are folded up outside the aperture and the aperture closing position in which the blade segments are expanded to cover the aperture. The follower arms are decreased in rigidity and/or impact resistance or in thickness relative to the main arms.