Patent ID: 6850281
Filing Date: 2005-02-01
Classification: G03B

Abstract:
1. A focal-plane shutter for digital still cameras, comprising: a shutter base plate provided with an exposure aperture; a first blade and a second blade for opening and closing said exposure aperture, each having a plurality of arms pivotally mounted on said shutter base plate and at least one blade component pivotally supported thereby; a first driving member for said first blade, connected to said first blade and actuated so that said first blade closes said exposure aperture with a biasing force of a cocking spring immediately before an exposure operation is started; a second driving member for said first blade, actuated by a biasing force of a driving spring for said first blade when said exposure operation is performed, and moving said first driving member for said first blade so that said first blade opens said exposure aperture against said biasing force of said cocking spring; retaining means for said first blade, retaining said second driving member for said first blade at a position where said exposure operation is started and releasing a retention of said second driving member for said first blade when said exposure operation is performed; a driving member for said second blade, connected to said second blade and moving said second blade so that said exposure aperture is closed by a biasing force of a driving spring for said second blade when said exposure operation is performed; retaining means for said second blade, retaining the driving member for said second blade at a position where said exposure operation is started and releasing a retention of said driving member for said second blade when said exposure operation is performed; and a cocking member, moving said second driving member for said first blade and said driving member for said second blade against biasing forces of respective driving springs when moved from an initial position to a cocked position and preventing said biasing force of said cocking spring from moving said first driving member for said first blade to put said exposure aperture to a fully opened state so that when said first driving member for said first blade is restored to said initial position from said cocked position at an initial stage of subsequent photography, said first driving member for said first blade can be actuated by said biasing force of said cocking spring.