Focal plane shutter and optical device using same

1. A focal plane shutter comprising:

a board including an opening;

blades capable of opening and closing the opening;

a drive member movable between a start position and a terminal position, biased toward the terminal position, and driving the blades;

a brake member supported to abut and move away from the drive member positioned at the terminal position, and biased to abut the drive member positioned at the terminal position; and

a set member rotatable in only one direction, and moving the drive member from the terminal position to the start position,

wherein the set member includes a drive portion abutting the brake member to move the brake member away from the drive member and then abutting the drive member to move the drive member toward the start position.

2. The focal plane shutter of claim 1 , further comprising:

a iron piece provided in the drive member; and

an electromagnet capable of adsorbing the iron piece of the drive member positioned at the start position,

wherein the drive portion moves away from the brake member and the drive member, thereby permitting the drive member to move from the start position to the terminal position based on energization of the electromagnet that is cut.

3. The focal plane shutter of claim 1 , wherein

the drive portion is a drive cam including:

a projection surface projected radially outward from a rotational center of the set member;

a receding surface receded radially inward as compared with the projection surface; and

an operation surface arranged between the projection surface and the receding surface,

the projection surface holds the brake member in a receding position where the brake member recedes from the drive member, and holds the drive member in the start position,

the receding surface permits the brake member and the drive member to move without abutting the brake member or the drive member, and

the operation surface moves the brake member away from the drive member and moves the drive member from the terminal position to the start position.

4. The focal plane shutter of claim 1 , wherein

the blades include leading blades and trailing blades,

the drive member includes a leading-blades drive member and a trailing-blades drive member respectively driving the leading blades and the trailing blades,

the brake member includes a leading-blades brake member and a trailing-blades brake member capable of respectively abutting and moving away from the leading-blades drive member and the trailing-blades drive member,

the drive portion includes a leading-blades drive portion and a trailing-blades drive portion,

the leading-blades drive portion abuts the leading-blades brake member to move the leading-blades brake member away from the leading-blades drive member and then abuts the leading-blades drive member to move the leading-blades drive member to the start position, and

the trailing-blades drive portion abuts the trailing-blades brake member to move the trailing-blades brake member away from the trailing-blades drive member and then abuts the trailing-blades drive member to move the trailing-blades drive member to the start position.

5. An optical apparatus comprising a focal plane shutter,

the focal plane shutter including:

a board including an opening;

blades capable of opening and closing the opening;

a drive member movable between a start position and a terminal position, biased toward the terminal position, and driving the blades;

a brake member supported to abut and move away from the drive member positioned at the terminal position, and biased to abut the drive member positioned at the terminal position; and

a set member rotatable in only one direction, and moving the drive member from the terminal position to the start position,

wherein the set member includes a drive portion abutting the brake member to move the brake member away from the drive member and then abutting the drive member to move the drive member toward the start position.