LIGHT AMOUNT ADJUSTMENT DEVICE CAPABLE OF ADJUSTING AMOUNT OF LIGHT AT HIGH SPEED AND WITH ACCURACY

摘要

A light amount adjustment device capable of adjusting the amount of light at high speed and with accuracy. When a rotary plate is rotatively driven by a motor, diaphragm blades disposed between the rotary plate and a cam plate are rotatively driven by the rotary plate in a plane perpendicular to an optical axis. When a coil disposed on the cam plate through aback yoke is energized and a magnetic field is generated around the coil, a magnetic attracting force is applied to the rotary plate rotating under the magnetic field, whereby the rotary plate is displaced toward the back yoke and frictions between the diaphragm blades and the rotary plate, etc. increase, so that rotations of the diaphragm blades are decelerated.