Actuator employing unidirectional motor for bidirectional rotational positioning

Apparatus utilizing a unidirectional motor for alternately rotating a member in opposite directions to alternately position said member at first and second positions, comprising:

• a first member mounted for rotation about a first axis;
• first and second stops positioned to limit rotation of said first member about the first axis, said first and second stops defining first and second limiting positions for said first member and defining a first angle through which said first member is permitted to rotate;
• a second member mounted for rotation about a second axis,
• a motor coupled to said second member and operable, when energized, to rotate said second member in a single direction only;
• a third member mounted for rotation about the first axis;
• a couple resiliently connecting said first and third member, and adapted to transfer torque about the first axis between the first and third members, while permitting said third member to rotate through a second angle greater than the first angle;
• a connecting link joining said second and third member, said connecting link being pivotally connected to said second and third members at first and second locations respectively, the distance between the first axis and second location being greater than the distance between the second axis and first location;
• and
• switch means through which energization can be supplied to said motor, said switch means being operable to interrupt energization to said motor substantially at the time said first member is rotated to either of said first and second stops.