1990-02-07
1990-12-04
Mathews, A. A.
354252, G03B 940
Patent
active
049757229
ABSTRACT:
A focal plane shutter includes a first blade group which is moved forward from an unfolding state to an overlapping state to start an exposure in response to the release of a first blade driving spring and a second blade group which is moved forward from an overlapping state to an unfolding state to terminate the exposure in response to the release of a second blade driving spring. The force of the driving springs for applying the impellent force to the blade groups is removed from the corresponding blade groups before each of the blade groups reaches an end of forward movement so that the blade groups are moved by the force of inertia. The driving spring for applying the impellent force to the blade groups is engaged with a first arm formed on one end of a swingably supported brake lever before the blade group reaches the end of forward movement so that a second arm formed on the other endd of the brake lever is rotated to prevent the movement of the blade group. Since the blade groups are moved to the end of forward movement while receiving the braking force by engagement with the second arms of the corresponding brake levers, shock or oscillation at the termination of forward movement is reduced.
REFERENCES:
patent: 4302091 (1981-11-01), Harase et al.
patent: 4692009 (1987-09-01), Toyoda et al.
patent: 4739355 (1988-04-01), Saito
patent: 4829329 (1989-05-01), Toyoda et al.
patent: 4847649 (1989-07-01), Toyoda et al.
Suzuki Akira
Watabe Ken-ichi
Copal Company Limited
Mathews A. A.
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