Patent ID: 8654429

Claim:
A light amount adjustment apparatus comprising: a base member formed with a fixed aperture through which light passes and plural cam groove portions; plural light-blocking blades arranged in a circumferential direction of the fixed aperture and forming a variable aperture through which the light passes, each light-blocking blade being provided with a driving pin and a cam pin engaging with one of the cam groove portions; a driving ring disposed on an opposite side of the light-blocking blades from a base member side of the light-blocking blades and rotating in the circumferential direction of the fixed aperture with respect to the base member to transmit a driving force to the driving pins so as to rotate the light-blocking blades for changing the size of the variable aperture; and a driving source part rotationally driving the driving ring, wherein a base-member-side blade face of each of the plural light-blocking blades is supported by the base member, wherein the driving ring is provided with (a) a ring-shaped portion and (b) first blade supporting portions each formed so as to protrude from the ring-shaped portion outward in a radial direction thereof and each formed with a driving hole portion with which one of the driving pins engages, wherein the ring-shaped portion is formed in a ring shape so as to connect ends of the plural first blade supporting portions in the circumferential direction, and wherein each of the plural first blade supporting portions supports an opposite-side blade face of one of plural light-blocking blades on the opposite side from the base-member-side blade face thereof.