US 4,047,807 AGranted

Diaphragm device

AssigneeMinolta Camera Kabushiki Kaisha

InventorsYukio Okano, Nobuyuki Kita, Kyozo Uesugi

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Abstract

A diaphragm device in which a plurality of diaphragm blades are arranged in partly overlapping relation to one another. This diaphragm device provides a diaphragm aperture of a substantially elongated circle having its length extending in a specific direction, when stopped down beyond a given diaphragm aperture. More particularly, the diaphragm aperture is defined by a pair of arcs which oppose each other in a direction perpendicular to the specific direction passing through the center of the aperture and another pair of arcs which are disposed on the opposite sides in the aforesaid specific direction, while the distance of either one of the pair of arcs to the center of the aperture is shorter than the distance of either of the other pair of arcs to the center of the aperture. These pairs of arcs define portions of the inner peripheral edges of the diaphragm blades.

Claims18

Dependent claims

A diaphragm device, comprising:

base plate means having a central opening of substantially circular shape;
first diaphragm blades each mounted on said base plate means in partially overlapping relation to form a diaphragm aperture defined by inner peripheral edges thereof each having a curved identical profile, said first blades each being mounted for pivotal movement through a predetermined angle to define said aperture of a predetermined size;
a pair of second diaphragm blades disposed opposite one another relative to the center of the opening in said base plate means, said second blades being mounted on said base plate means in partially overlapping relation to said first blades, and said second blades each being mounted for pivotal movement through an angle greater than said predetermined angle so that the inner peripheries of said second blades may shield part of the aperture defined by said inner peripheries of said first blades to thereby reduce said predetermined size of said aperture, said inner peripheries of said second blades each having a curved identical profile;
means engaging each of said blades for pivoting them to vary the size of the diaphragm aperture, said means which engage said second blades causing them, when it is desired to reduce said predetermined size of said aperture, to pivot further than said first blades are caused to thereby pivot so as to define a part of said aperture, whereby said peripheral edges of said second blades defines with a portion of said peripheral edges of said first blades an elongated aperture by reason of the opposed relation of said second blades and their greater angular movement.

1 more element

A diaphragm device, comprising:

a base plate having a central opening of circular shape;
an operating ring coupled to said plate for relative rotation and having a central circular opening superimposed over said plate opening;
a plurality of diaphragm blades disposed between said plate and said ring in partially overlapping ralation to one another to define a diaphragm aperture by the inner peripheral edges thereof, said blades being pivotally mounted to said plate and to said ring for movement upon relative rotation of said ring and said plate, said blades having pins on opposite sides thereof seated within holes provided in said plate and within slots provided in said ring, a pair of opposing ones of said blades being mounted in place for a first angular movement, the remainder of said blades being mounted in place for a second angular movement less than said first angular movement, whereby a substantially rectangular diaphragm aperture is formed by said inner peripheral edges of said opposing blades and a pair of said remainder blades.

A diaphragm device, including:

an objective lens;
an optical low pass filter for cutting off the high spacial frequency for preventing a false color produced in an image due to a beat caused between a color signal carrier of a color encoding filter and the high frequency components of said image formed by said objective lens, said optical low pass filter having a transparent substrate and a phase grating which causes retardation of light passing through the filter;
a plurality of diaphragm blades partially overlapping to define a diaphragm aperture by the inner peripheral edges thereof, said aperture being concentric with the center of said lens;
means cooperating with said blades for stopping them down to a minimum diaphragm aperture which is elongated in a direction perpendicular to strips of the grating and which covers at least two of said strips of the grating,
whereby the diaphragm opening may be stopped down to a large f-number without sacrificing the function of said optical low pass filter to cut off the high spacial frequency.

2 more elements

Dependencies are inferred from the claim text.