Patent ID: 6867932

Claim:
An iris type light quantity adjusting device comprising: a fixed member, said fixed member having a fixed opening for light to pass through, and a plurality of shafts being placed around said fixed opening; a plurality of shading blades, each shading blade pivoting around each shaft outward and inward in a direction orthogonal to an optical axis to adjust quality of light passing through said iris type light quality adjusting device, wherein at least one shading blade among said plurality of shading blades has extended portion overlapping the other shading blade in order to keep overlapping order in an optical axis direction with said other shading blade that pivots around the shaft not adjacent to the shaft as a pivot of said at least one shading blade in the circumferential direction of said fixed opening, each of said plurality of shading blades has one or none intersection between an outer edge of said shading blade at an outside in the direction orthogonal to the optical axis and a peripheral edge of said fixed opening within an entire pivoting range of each of said shading blades, and one of a pair of shading blades approaching from substantially opposite directions in the direction orthogonal to the optical axis during pivoting to a closing direction has, at the tip thereof, a shape not overlapping the other shading blade in a closed position. said one of the pair of shading blades approaching from said sustantially opposite directions during pivoting the the closing direction may overlap, at the tip thereof, said other shading blade by further pivoting from the closed position to the closing direction.