Lens unit driven by a motor or manually with a torque limiting member

摘要

An optical apparatus includes an optical unit, a manual operation ring for manually driving the optical unit, a driving motor for electrically driving the manual operation ring, a transmission driving force limiting member for limiting a transmission driving force between the manual operation ring and the driving motor, the transmission driving force limiting member being formed in a ring shape substantially cocentric with an optical axis of the optical unit, a speed reduction gear for transmitting a driving force from the driving motor to the transmission driving force limiting member, wherein the following condition is satisfied: $where\; TL\; is\; a\; torque\; required\; for\; driving\; the\; manual\; operation\; ring,\; which\; is\; disposed\; on\; the\; side\; of\; the\; optical\; unit\; relative\; to\; the\; transmission\; driving\; force\; limiting\; member,\; and\; the\; optical\; unit,\; TF\; is\; a\; limit\; torque\; transmissible\; by\; the\; transmission\; driving\; force\; limiting\; member,\; and\; TM\; is\; a\; limit\; torque\; with\; which\; a\; driving\; system\; composed\; of\; the\; driving\; motor\; and\; the\; speed\; reduction\; gear\; can\; be\; kept\; stopped\; against\; driving\; from\; an\; output\; side\; of\; the\; driving\; system.\; Accordingly,\; the\; optical\; unit\; can\; be\; driven\; either\; with\; the\; driving\; motor\; or\; by\; a\; manual\; operation\; on\; the\; manual\; operation\; ring\; without\; recourse\; to\; any\; switch-over\; mechanism.\mathop{\mathrm{image}}$