Apparatus for switching visual field frame of view finder, operation apparatus therefor, and apparatus for acturating rotary operation member having neutral position

A field frame switching apparatus for a finder in which an elongate standard visual field, a narrow-width visual field in which said standard visual field is partly interrupted at right and left ends thereof, and a laterally-elongated visual field in which said standard visual field is partly blocked out at upper and lower ends thereof can be selected, comprising:

• a pair of narrow-width visual-field-forming light-interception frames which are movable in the right and left directions of said standard visual field and which are provided with vertical light-interception walls which are adapted to block out the right and left ends of said standard visual field, said narrow-width visual-field-forming light-interception frames substantially forming a rectangle therebetween;
• a pair of laterally-elongated visual-field-forming light-interception frames which are movable in the upward and downward directions of said standard visual field and which are provided with lateral-light-interception walls which are adapted to block out the upper and lower ends of said standard visual field;
• an operation member which is adapted to move said laterally-elongated visual-field-forming light-interception frames in a first direction toward a laterally-elongated field-frame-forming position in which said lateral-light-interception walls are located within the standard visual field frame and in a second direction toward a narrow-width field-frame-forming position, with respect to a standard field-frame-forming position in which said lateral-light-interception walls are located out of said standard visual field frame;
• and
• an association movement mechanism comprising a pair of projections provided on one of said narrow-width field forming light-interception frames adapted to move said vertical light-interception walls of said narrow-width field forming light-interception frames into or from said standard visual field frame in association with the movement of said laterally-elongated field forming light-interception frames when said laterally-elongated field forming light-interception frames are moved between said standard field-frame-forming position and said narrow-width field-frame-forming position.

A field frame switching apparatus for a finder in which an elongated standard visual field, a narrow-width visual field in which said standard visual field is partly blocked out at right and left ends thereof, and a laterally-elongated visual field in which said standard visual field is partly blocked out at upper and lower ends thereof can be selected, comprising:

• a first plate having an opening for a standard visual field;
• a pair of narrow-width visual-field-forming light-interception frames which are movable in the right and left directions of said standard visual field and which are provided with vertical light-interception walls are adapted to block out the right and left ends of said standard visual field;
• a pair of laterally-elongated visual-field-forming light-interception frames which are movable in the upward and downward directions of said standard visual field and which are provided with lateral-light-interception walls which are adapted to block out the upper and lower ends of said standard visual field;
• an operation member which is adapted to move said narrow-width visual-field-forming light-interception frames in a first direction toward a narrow-width field-frame-forming position in which said vertical light-interception walls are located within said standard visual field frame and in a second direction toward a laterally-elongated field-frame-forming position with respect to a standard field-frame-forming position in which said vertical light-interception walls are located out of said standard visual field frame;
• an association movement mechanism which moves said lateral-light-interception walls of said laterally-elongated field forming light-interception frames into or from said standard visual field frame in association with the movement of said narrow-width field forming light-interception frames when said narrow-width field forming light-interception frames are moved between said standard field-frame-forming position and said laterally-elongated field-frame-forming position;
• and
• a second plate having an opening for a standard visual field which corresponds to the opening of said first plate, said first and second plates holding said narrow-width field forming light-interception frames, said laterally-elongated field forming light-interception frames, and said association movement mechanism therebetween so as to form an assembly unit.

An operation apparatus for a field frame switching mechanism of a finder comprising:

• a field frame switching mechanism which is adapted to change the size of the field frame among an elongated standard visual field, a narrow-width visual field in which the standard visual field is partly blocked out at right and left ends thereof, and a laterally-elongated visual field in which said standard visual field is partly blocked out at upper and lower ends thereof;
• a swing member which has an axis about which the swing member is rotated, said swing member actuating the field frame switching mechanism by the swing movement thereof about the axis;
• a shaft member separate from the swing member, said shaft member being rotatable about a central shaft portion thereof, said shaft member rotating the swing member about the axis thereof when the shaft member is rotated about the central shaft portion;
• said shaft member being provided with a neutral angular position and predetermined forward and rearward angular positions in opposite directions from the neutral angular position, so that said field frame switching mechanism defines said standard visual field through said swing member when the shaft member is in the neutral angular position, and defines said narrow-width visual field and said laterally-elongated visual field when said shaft member is located in the predetermined forward and rearward angular positions, respectively;
• and
• a spring means for normally holding said shaft member at said neutral angular position and for exerting a spring force on said shaft member to return the same to said neutral angular position when said shaft member is rotated in a predetermined forward and rearward directions from said neutral angular position.

An operation apparatus for a rotary operation member having a neutral position, comprising

• a shaft member having a central shaft portion and a radial projection extending from the central shaft portion in the radial direction, said shaft member being rotatable about the central shaft portion;
• said shaft member being provided with a neutral angular position and predetermined angular forward and rearward positions in opposite directions from said neutral angular position;
• a first torsion spring means for normally holding said shaft member at said neutral angular position and for exerting a spring force on said shaft member to return the same to said neutral angular position when said shaft member is rotated in a predetermined direction from said neutral angular position;
• a dial member which can be externally rotated;
• a second torsion spring means having a coil portion which is supported by the shaft portion of said dial member and a pair of spring ends which are biased in a direction to come close to each other so that said radial projection of the shaft member is located between the spring ends, said second torsion spring means being stronger than said first torsion spring means;
• and
• a stop means provided on said dial member, for keeping the distance between the spring ends of said second torsion spring means, in the free state, at a predetermined value so that said radial projection is inserted between the spring ends within a certain tolerance.