Abstract: A miniature camera (1) comprising at least one SMA actuator wire (11) arranged to effect focus, zoom or optical image stabilization. The SMA actuator wire (11) is coated with an electrically insulating layer (40) of thickness in the range from 0.3 ?m to 10 ?m. The layer (40) provides electrical insulation whilst permitting cooling that provides a rapid response time of the SMA atuator wire (11).

Abstract: SMA actuator wires in an SMA actuation apparatus are connected in tension between a movable element and a support structure, applying forces to the movable element in opposed directions. Measures of the resistances of the SMA actuator wires are detected. A feedback difference measure is derived being the sum of the measures of resistance of the SMA actuator wires, relatively scaled by factors, in respect of the SMA actuator wires, the magnitude of which represents a component along the predetermined axis of a force applied by the SMA actuator wire and the sign of which represents a direction along the predetermined axis. The ratio has opposite signs for respective ones of said opposed directions. The powers of drive signals supplied to the SMA actuator wires are controlled in response to the feedback difference measure to reduce the difference between the feedback difference measure and a target difference measure.

Abstract: Methods and apparatus are disclosed for actuating a shape-memory alloy actuator. An example method comprises a measurement phase, in which a voltage is applied across a bridge comprising a sense resistor to measure the resistance of the shape-memory alloy actuator, and a drive phase, in which a bypass unit is used to bypass the sense resistor while still driving current through the shape-memory alloy actuator in order to drive the shape-memory alloy actuator.

Abstract: An SMA actuation apparatus moves a movable element, such as a camera lens element, relative to a support structure in any direction perpendicular to a notional primary axis using N pairs of SMA actuator wires extending perpendicular to said primary axis, where N is three or more. The SMA actuator wires of each pair extend parallel to each other and being connected at their ends in tension to the movable element and the support structure in opposition to apply a force to the movable element in opposite directions. The SMA actuator wires are arranged around the movable element such that they are capable of being selectively driven to move the movable element in any direction perpendicular to said primary axis. Accordingly, it is possible to drive movement with an apparatus that is compact along the primary axis.

Abstract: A camera lens element is suspended on a support structure by balls that allow movement of the camera lens elementorthogonal to the optical axis and plural flexures connected between the support structure and the camera lens element to bias them against the balls whilst permitting said movement of the camera lens elementorthogonal to the optical axis. Lateral movement is driven by a lateral actuation arrangement comprising plural SMA actuator wires. The flexures provide a lateral biasing force that biases the camera lens element towards a central position. An electrical connection is made through the flexures from the support structure to the camera lens element. The flexures may be connected to laminated structures.

Abstract: Methods and apparatus are disclosed for actuating a shape-memory alloy actuator. An example method comprises a measurement phase, in which a voltage is applied across a bridge comprising a sense resistor to measure the resistance of the shape-memory alloy actuator, and a drive phase, in which a bypass unit is used to bypass the sense resistor while still driving current through the shape-memory alloy actuator in order to drive the shape-memory alloy actuator.

Abstract: In a camera apparatus, two SMA actuator subsystems each comprise two SMA wires connected between a camera unit and a support structure, hooked over a pivot element defining pivot axes that lie in a common plane along the optical axis. Differential contraction of the SMA wires drives rotation. The SMA actuator subsystems are opposed, but the SMA wires of each subsystem are fixed respectively to the camera unit and the support structure, reducing the height. A non-conductive substrate supporting conductive tracks electrically connected to the SMA actuator system is configured as a flexure arrangement between the camera unit and the support structure. The flexure arrangement is connected to the camera unit at a position in the common plane reducing lateral resistance to tilt. Use of an intermediate connector element allows the circuit board to be arranged in front of the intermediate connector inside the height of the lens system.

Abstract: An SMA actuation apparatus moves a movable element relative to a support structure in two orthogonal directions using a total of four SMA actuator wires each connected at its ends between the movable element and the support structure and extending perpendicular to the primary axis. None of the SMA actuator wires are collinear, but the SMA actuator wires have an arrangement in which they are capable of being selectively driven to move the movable element relative to the support structure to any position in said range of movement without applying any net torque to the movable element in the plane of the two orthogonal directions around the primary axis. Accordingly, it is possible to drive movement whilst balancing the forces to limit torque around the primary axis.

Abstract: An SMA actuation apparatus moves a movable element, such as a camera lens element, relative to a support structure in any direction perpendicular to a notional primary axis using N pairs of SMA actuator wires extending perpendicular to said primary axis, where N is three or more. The SMA actuator wires of each pair extend parallel to each other and being connected at their ends in tension to the movable element and the support structure in opposition to apply a force to the movable element in opposite directions. The SMA actuator wires are arranged around the movable element such that they are capable of being selectively driven to move the movable element in any direction perpendicular to said primary axis. Accordingly, it is possible to drive movement with an apparatus that is compact along the primary axis.

Abstract: A camera apparatus capable of providing optical image stabilization comprises: a support structure; a camera unit comprising an image sensor and a lens system; a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt; and a plurality of SMA actuators. A sensor arrangement, whose output is used as the basis for generating drive signals, is mounted on the camera unit. A control circuit generates drive signals for the SMA actuators, by deriving closed-loop control signals representative of a desired degree of variation in the power of the drive signals from the output signals of the sensor arrangement without dependence on any measurement of the resistance of the SMA actuators, and generating the drive signals with powers that varies from a set-point power in correspondence with the closed-loop control signal.

Abstract: A camera apparatus capable of providing optical image stabilization comprises: a support structure; a camera unit comprising an image sensor and a lens system; a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt; and a plurality of SMA actuators each formed as SMA wire connected between the camera unit and the support structure and arranged on contraction to drive tilting of the camera unit. The SMA wire may be fixed to the camera unit at its ends and hooked over an element of the support structure. A vibration sensor, whose output is used as the basis for generating drive signals, may be mounted on the camera unit.

Abstract: An SMA actuation apparatus uses SMA actuator wires to move a movable element supported on a support structure, for example to provide optical image stabilization. Eight SMA actuator wires are arranged inclined with respect to a notional primary axis with a pair of the SMA actuator wires on each of four sides around the primary axis. The SMA actuators are connected so that on contraction two groups of four SMA actuator wires provide a force with a component in opposite directions along the primary axis, so that the groups are capable of providing movement along the primary axis. The SMA actuator wires of each group have 2-fold rotational symmetry about the primary axis, so that there are SMA actuator wires opposing each other that are capable of providing lateral movement or tilting.

Abstract: An SMA actuation arrangement comprises: an SMA actuator arranged on contraction caused by heating to drive movement of a movable element relative to a support structure; a current source operative to supply drive current through the SMA actuator to heat the SMA actuator; and a detector circuit operative to detect a measure of the resistance of the SMA actuator. While detecting a measure of the resistance of the SMA actuator and controlling the drive current on the basis of the measure of the resistance of the SMA actuator; there is derived a measure of an electrical characteristic of the SMA actuator that is representative of the ambient temperature. While applying closed-loop control an offset is added to the control signal which reduces the steady-state value of an error between the measure of the resistance of the SMA actuator and a target value.

Abstract: A camera apparatus capable of providing optical image stabilisation comprises: a support structure; a camera unit comprising an image sensor and a lens system; a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt; and a plurality of SMA actuators. A sensor arrangement, whose output is used as the basis for generating drive signals, is mounted on the camera unit. A control circuit generates drive signals for the SMA actuators, by deriving closed-loop control signals representative of a desired degree of variation in the power of the drive signals from the output signals of the sensor arrangement without dependence on any measurement of the resistance of the SMA actuators, and generating the drive signals with powers that varies from a set-point power in correspondence with the closed-loop control signal.

Abstract: A shape memory alloy actuation apparatus comprises a movable element supported on a support structure by a suspension system comprising a plurality of resilient flexures. A shape memory alloy actuator drives movement of the movable element on contraction. An end-stop limits the movement of the movable element in the opposite direction. Rather than using the resilient flexures of the suspension system as the sole biassing means, an additional Massing element biasses the movable element against the SMA actuator. When the moveable element is held against the end-stop, the force applied by the biassing element is greater than the force applied by the flexures of the suspension system. This reduces the design constraints, for example allowing a greater range of movement.

Abstract: A shape memory alloy actuation apparatus comprises a movable element suspended on a support structure by a plurality of flexures which are non-uniformly configured to apply forces having differing components perpendicular to the movement axis generating a net moment around the center of mass of the movable element in an opposite sense from the moment generated by the actuation force. A shape memory alloy wire is coupled between the support structure and an intermediate body engaging the movable element through a pivotal contact to avoid lateral force transfer. Also coupled between the support structure and the intermediate body is a resilient biassing flexure plastically deformed in a partial region thereof. The shape memory alloy wire is crimped by a crimping member fixed to the support structure holding the shape memory alloy wire against a curved surface from which the shape alloy memory wire extends to the movable element.

Abstract: An SMA actuation apparatus comprises a support structure, a movable element movably supported on the support structure and an arrangement of three or more SMA actuator wires mechanically connected between the support structure and the movable element. The SMA actuator wires have an interconnection at the movable element that electrically connects the group of SMA actuator wires together. This avoids the need to make a separate electrical connection to the movable element.

Abstract: A camera apparatus capable of providing optical image stabilization comprises a support structure and a camera unit, that comprises an image sensor and a lens system for focussing an image thereon, supported on the support structure in a manner allowing it to tilt around two notional axes perpendicular to each other and to the optical axis. An SMA actuation system comprises two SMA actuator subsystems each comprising plural SMA actuators connected between the camera unit and the support structure. The SMA actuators of the respective SMA actuator subsystems are arranged, on contraction, to drive displacement of the camera unit in opposite directions along the optical axis. The SMA actuators of each SMA actuator subsystem are also arranged, on differential contraction, to drive rotation of the camera unit around a respective one of said notional axes.

Abstract: A sound reproduction system for producing sound and 3D sound at the listener position by directing beams from an array loudspeaker using differential apodisation. Optionally, cross-talk cancellation is applied to beams directed to the listener's left and right ears.

Abstract: In a camera apparatus, two SMA actuator subsystems each comprise two SMA wires connected between a camera unit and a support structure, hooked over a pivot element defining pivot axes that lie in a common plane along the optical axis. Differential contraction of the SMA wires drives rotation. The SMA actuator subsystems are opposed, but the SMA wires of each subsystem are fixed respectively to the camera unit and the support structure, reducing the height. A non-conductive substrate supporting conductive tracks electrically connected to the SMA actuator system is configured as a flexure arrangement between the camera unit and the support structure. The flexure arrangement is connected to the camera unit at a position in the common plane reducing lateral resistance to tilt. Use of an intermediate connector element allows the circuit board to be arranged in front of the intermediate connector inside the height of the lens system.