Drive system for rotatable optical element

摘要

A drive system includes a rotational driving member, a rotational driven member, to which a rotational resistance is applied, a holding member of a rotatable optical element supported by the rotational driving member and the rotational driven member, an insertion controller preventing the holding member from rotating when the holding member is in an inserted position, and a removal controller allowing the holding member to move to a fully removed position and prevents the holding member from rotating at a limited removed position. An insertion/removal operation of the holding member is performed by relative rotation between the rotational driving member and the rotational driven member, and when the holding member is prevented from rotating by the insertion controller and the removal controller, the rotational driven member and the holding member rotate with the rotational driving member about the optical axis.

主权项

1. A drive system for a rotatable optical element which is insertable into and removable from an optical path of a photographing optical system, and also rotatable about an optical axis of said photographing optical system when said rotatable optical element is positioned in said optical path, said drive system comprising:
a support member; a rotational driving member which is supported by said support member to be rotatable about said optical axis and which is driven to rotate about said optical axis by a driving source; a rotational driven member which is supported by said support member to be rotatable about said optical axis and which is rotatable about said optical axis relative to said rotational driving member; a resistance applier which applies rotational resistance to said rotational driven member; a holding member which holds said rotatable optical element, includes a rotation transmission portion, to which a force in a rotational direction about said optical axis is transmitted from said rotational driving member, and a pivotal support portion pivotally supported on said rotational driven member, wherein said holding member inserts and removes said rotatable optical element into and from said optical path by forward and reverse rotations of said holding member about said pivotal support portion; an insertion controller which prevents said holding member from rotating when said holding member is in an inserted position, in which said rotatable optical element is inserted into said optical path; and a removal controller which allows said holding member to move to a fully removed position from said optical path when said holding member is positioned at a specific position in a rotational direction of said holding member about said optical axis, and said removal controller prevents said holding member from rotating about said pivotal support portion at a limited removed position, wherein said limited removed position is located radially closer to said optical axis than said fully removed position, when said holding member is positioned at any other position in said rotational direction of said holding member, wherein a differential rotation occurs between said rotational driven member, to which said resistance applier applies said rotational resistance, and said rotational driving member to thereby cause said holding member to rotate in an optical-element insertion/removal direction about said pivotal support portion by rotating said rotational driving member in a direction in which said holding member is not prevented from rotating by said insertion controller and said removal controller, wherein said rotational driven member and said holding member rotate with said rotational driving member about said optical axis against said rotational resistance, which is applied to said rotational driven member by said resistance applier, by rotating said rotational driving member in a direction in which said holding member is prevented from rotating by said insertion controller when said holding member is in said inserted position, and wherein said rotational driven member and said holding member rotate with said rotational driving member about said optical axis against said rotational resistance, which is applied to said rotational driven member by said resistance applier, by rotating said rotational driving member in a direction in which said holding member is prevented from rotating by said removal controller when said holding member is positioned at said limited removed position, and said holding member rotates to said fully removed position by rotating said rotational driving member in said direction, in which said holding member is prevented from rotating by said removal controller, upon being positioned at said specific position in said rotational direction of said holding member.