SHAPE MEMORY ALLOY ACTUATION APPARATUS
First Claim
1. A shape memory alloy actuation apparatus comprising:
- a support structure;
a movable element;
a suspension system comprising a plurality of flexures coupled between the support structure and the movable element to support the movable element on the support structure and to guide movement of the movable element along a movement axis by deflection of the flexures, the flexures including at least one first flexure and at least one second flexure arranged at different positions along the movement axis;
at least one shape memory alloy wire connected between the support structure and the movable element at an acute angle to the movement axis, the shape memory alloy wire on contraction applying a force to the movable element having a component in a first direction along the movement axis and a component perpendicular to the movement axis;
a biassing element connected between the support structure and the movable element and arranged to apply a biassing force to the movable element in a second direction along the movement axis opposite to said first direction,wherein the shape memory alloy actuation apparatus is arranged such that said component of force applied perpendicular to the movement axis compresses the flexures with a compressive force sufficiently high that, across at least part of the range of movement of the movable element along the movement axis, the flexures apply a force to the movable element having a component along the movement axis that is in the same direction as said component of force applied by the shape memory alloy wire along the movement axis.
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Accused Products
Abstract
An SMA actuation apparatus comprises a camera lens element supported on a support structure by a plurality of flexures. An SMA wire at an acute angle to the movement axis and a biassing element are connected between the support structure and the movable element. A component of the force applied by the SMA wire perpendicular to the movement axis compresses the flexures causing them to apply a force to the movable element having a component along the movement axis in the same direction as the SMA wire. An end-stop limits the movement of the movable element, and the moment applied by the end-stop to the movable element about the centre of stiffness is equal to the moment applied by the SMA wire about the centre of stiffness at the point when the movable element loses contact with the end-stop on contraction of the SMA wire.
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Citations
19 Claims
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1. A shape memory alloy actuation apparatus comprising:
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a support structure; a movable element; a suspension system comprising a plurality of flexures coupled between the support structure and the movable element to support the movable element on the support structure and to guide movement of the movable element along a movement axis by deflection of the flexures, the flexures including at least one first flexure and at least one second flexure arranged at different positions along the movement axis; at least one shape memory alloy wire connected between the support structure and the movable element at an acute angle to the movement axis, the shape memory alloy wire on contraction applying a force to the movable element having a component in a first direction along the movement axis and a component perpendicular to the movement axis; a biassing element connected between the support structure and the movable element and arranged to apply a biassing force to the movable element in a second direction along the movement axis opposite to said first direction, wherein the shape memory alloy actuation apparatus is arranged such that said component of force applied perpendicular to the movement axis compresses the flexures with a compressive force sufficiently high that, across at least part of the range of movement of the movable element along the movement axis, the flexures apply a force to the movable element having a component along the movement axis that is in the same direction as said component of force applied by the shape memory alloy wire along the movement axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A shape memory alloy actuation apparatus comprising:
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a support structure; a movable element; a suspension system comprising a plurality of flexures coupled between the support structure and the movable element to support the movable element on the support structure and to guide movement of the movable element along a movement axis by deflection of the flexures, the flexures providing a centre of stiffness at which a force applied to the movable element would not tend to rotate the movable element; at least one shape memory alloy wire connected between the support structure and the movable element at an acute angle to the movement axis, the shape memory alloy wire on contraction applying a force to the movable element having a component in a first direction along the movement axis and a component perpendicular to the movement axis; an end-stop arranged to limit the movement of the movable element in a second direction along the movement axis opposite to said first direction, wherein the shape memory alloy actuation apparatus is arranged such that the moment applied by the end-stop to the movable element about the centre of stiffness when the shape memory alloy wire is not contracted is equal to the moment applied by the shape memory alloy wire to the movable element about the centre of stiffness at the point when the movable element loses contact with the end-stop on contraction of the shape memory alloy wire. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification