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: 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: 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 comprises: an SMA actuator arranged to drive movement of a movable element; a current supply supplying a drive current; a detection circuit detecting a measure of the resistance of the SMA actuator; and a control unit operative to generate a closed-loop control signal supplied to current supply for controlling the power of the drive current to drive the resistance of the SMA actuator to a target value. The control unit derives: an estimate of a characteristic temperature of the SMA actuation apparatus on the basis of the supplied power, using a thermal model; and a resistance offset on the basis thereof. The closed-loop control signal is generated on the basis of the error between the measure of the resistance of the SMA actuator and the target value of the resistance of the SMA actuator, adjusted by the resistance offset to compensate for variations in resistance.

Abstract: A miniature camera lens actuation apparatus comprises a support structure, a camera lens element supported on the support structure by a suspension system; and an SMA actuator connected between the support structure and the movable element to drive movement of the camera lens element. The control circuit may include a drive circuit and a sensor circuit which have separate electrical connections to the SMA actuator to reduce the impact of the resistance of the electrical connections on the sensing. The control circuit may vary the drive signal in response to a temperature signal indicative of the ambient temperature. An endstop limits movement to prevent extension of the SMA actuator in its unheated state beyond a maximum length which is at or below the length corresponding the local maximum resistance of the resistance-length curve. Control of position is effected using resistance of the SMA actuator as a measure of position.

Abstract: The present invention combines a head-tracking system, for example a camera system typically used for user head and eye tracking, with a plurality of loudspeakers to as to enhance the audio experience of the user. The location of the user can be used to alter the audio signal sent to the plurality of loudspeakers to improve such functions as surround sound. In addition, the camera system can be used, when combined with an array of loudspeakers that can produce tight beams of sound, to direct different sound beams at different users, with virtually no crosstalk so as to allow users to experience different media from the same audio system, and which is tolerant of changed user positions. In addition, the camera system can aid setting up the array for real surround sound delivery, which bounces sound beams off wall. Cross-talk cancellation can additionally be used. The sound beams may represent 2-D or 3-D sound sources in real time.

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 biasing 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 center of stiffness is equal to the moment applied by the SMA wire about the center of stiffness at the point when the movable element loses contact with the end-stop on contraction of the SMA wire.

Abstract: A shape memory alloy actuation apparatus comprises a camera lens element supported on the support structure by a plurality of resilient flexures that guide movement of the movable element along the optical axis. A shape memory alloy actuator biassed by the resilient flexures and an additional resilient biassing element is arranged to drive movement of the camera lens element. An end-stop limits movement of the camera lens element at a position where the shape memory alloy actuator has a predetermined length that is above the length corresponding on the local maximum resistance by an amount not greater than 15% of the difference between (i) the length corresponding to the local maximum resistance and (ii) the length corresponding to the local minimum resistance.

Abstract: A camera lens actuation apparatus for driving motion of a camera lens supported on a support structure by a suspension system. The apparatus incorporates a subassembly comprising SMA wire connected to at least one mounting member which is mounted to the support structure. At least one pair of lengths of SMA wire are held in tension between the camera lens element and the support structure at respective acute angles to the optical axis applying a tensional force having a component along the optical axis. The lengths of SMA wire in the pair are held at angle as viewed along the optical axis. There may be plural pairs with a balanced arrangement in which the forces generated have no net component perpendicular to the optical axis and generate no net torque around any axis perpendicular to the optical axis. A control circuit controls heating of the SMA wire in response to a measure of its resistance.

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 stabilisation. 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: A miniature camera lens actuation apparatus provides an auto-macro function in which a camera lens element has two focus positions. In one type of apparatus, a shape memory alloy actuator arranged to drive movement of the camera lens element relative to a support structure against an end-stop arranged to limit the movement. The shape memory alloy actuator is connected to one of the movable element and the support structure by a compliant connector. This limits the stresses on the shape memory alloy actuator and therefore increases its lifetime. In another type of apparatus, the suspension system supporting the movable element on the support structure provides the movable element with two stable positions along the movement direction.

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.

Abstract: An SMA actuation apparatus comprises: an SMA actuator arranged to drive movement of a movable element; a current supply supplying a drive current; a detection circuit detecting a measure of the resistance of the SMA actuator; and a control unit operative to generate a closed-loop control signal supplied to current supply for controlling the power of the drive current to drive the resistance of the SMA actuator to a target value. The control unit derives: an estimate of a characteristic temperature of the SMA actuation apparatus on the basis of the supplied power, using a thermal model; and a resistance offset on the basis thereof. The closed-loop control signal is generated on the basis of the error between the measure of the resistance of the SMA actuator and the target value of the resistance of the SMA actuator, adjusted by the resistance offset to compensate for variations in resistance.

Abstract: A shape memory alloy actuation apparatus comprises a camera lens element supported on the support structure by a plurality of resilient flexures that guide movement of the movable element along the optical axis. A shape memory alloy actuator biassed by the resilient flexures and an additional resilient biassing element is arranged to drive movement of the camera lens element. An end-stop limits movement of the camera lens element at a position where the shape memory alloy actuator has a predetermined length that is above the length corresponding on the local maximum resistance by an amount not greater than 15% of the difference between (i) the length corresponding to the local maximum resistance and (ii) the length corresponding to the local minimum resistance.