Variable aperture diaphragm for lens - has guide rings and movable rings occupying cylindrical volume

摘要

A diaphragm of jointed vanes (3) has a first guide ring (1). A second movable ring (2) rotates about its axis, concentric with first ring. The vanes each have studs (4) to ensure mechanical alignment with the rings. They have a predetermined shape to together define an appreciably circular surface. There are means of simultaneously driving the second ring and the vanes, to continuously vary the diameter of the shape between a minimum and a maximum value. The rings (1, 2) occupy a cylindrical volume of diameter approximately equal to the minimum value (D1). The vanes (3) are driven by the centrifugal force outside the volume to occupy the different positions between the minimum and maximum values (D2).