A moving-coil closed-loop auto-focusing module with low magnetic interference includes an upper cover, a base frame, a lens module, an elastic module, at least one coil, at least one pair of two opposing driving magnets, an external circuit and at least one sensor magnet. The coil surrounds the lens module. The two driving magnets are located individually at respective lateral sides of the base frame in correspondence with the coil. The external circuit located under the base frame includes an image-sensing element and at least one sensor. The sensor magnet is mounted peripherally to the lens module, and has magnetic lines parallel to the optical image-capturing axis, such that a magnetizing surface of the sensor magnet can face downward to align the sensor on the external circuit. Thereupon, the lens module can be controlled to displace along an optical image-capturing axis in a closed-loop manner.

An isomagnetic speaker comprising a diaphragm and an interference-free magnet structure is described herein. The interference-free magnet structure comprises a magnet array disposed to correspond with a predetermined region of the diaphragm and comprising a plurality of permanent magnets disposed at equal intervals along at least one direction. A plurality of bottoms of the plurality of permanent magnets are arranged on a same plane and oriented toward the diaphragm. A magnetic field direction of each permanent magnet is perpendicular to a corresponding bottom. A maximum size of a length of each permanent magnet along a direction parallel to the diaphragm is smaller than or equal to c/2f.sub.min, wherein c is a sound wave speed, and f.sub.min is a minimum output audio frequency of the isomagnetic speaker.

An array type magnetic circuit system includes a T yoke, magnetic steels and a washer. The T yoke includes a bottom plate, and more than two central columns located on the bottom plate and distributed in an array. The magnetic steels are respectively disposed at two sides of each of the central columns and provide a magnetic energy for the magnetic circuit system. Hole positions coupled with the central columns correspondingly are formed on the washer and the washer is tightly connected to the T yoke. According to the array type magnetic circuit system, under a condition in which a plurality of magnetic circuits are combined, the T yoke and the washer are respectively taken as a component, so that the precision of a product can be controlled better.

An apparatus may include a rotatable permanent magnet exhibiting a magnetic field. Alternatively, the actuation apparatus may include a set of coils configured to generate a rotatable magnetic field. The apparatus may further include a magnetic shape memory (MSM) element including MSM material and having a long axis, where the MSM element is configured to contract locally in a first part in response to local exposure to a first component of the magnetic field that is substantially perpendicular to the long axis and to not contract locally in a second part that is exposed to a second component of the magnetic field that is not substantially perpendicular to the long axis. The apparatus may include a first fixed magnet positioned at a first end of the MSM element and a second fixed magnet positioned at a second end of the MSM element.

The present disclosure provides an improved speaker including a suspension accommodated in a magnetic gap formed by a main magnet and an auxiliary magnet. The suspension is used for supporting a coil assembly of the speaker. The auxiliary magnet further includes a capacity-increased space for accommodating the suspension and providing the suspension with more space to vibrate and providing the suspension with better flexibility. In order to more firmly fix the suspension, the auxiliary magnet further includes a fastening slot for engaging with an edge of the suspension. Optionally, the auxiliary magnet is configured to be a two-piece structure.

A moving-coil closed-loop auto-focusing module with low magnetic interference includes an upper cover, a base frame, a lens module, an elastic module, at least one coil, at least one pair of two opposing driving magnets, an external circuit and at least one sensor magnet. The coil surrounds the lens module. The two driving magnets are located individually at respective lateral sides of the base frame in correspondence with the coil. The external circuit located under the base frame includes an image-sensing element and at least one sensor. The sensor magnet is mounted peripherally to the lens module, and has magnetic lines parallel to the optical image-capturing axis, such that a magnetizing surface of the sensor magnet can face downward to align the sensor on the external circuit. Thereupon, the lens module can be controlled to displace along an optical image-capturing axis in a closed-loop manner.

A reluctance transducer includes a soft ferromagnetic yoke and a soft ferromagnetic core element, which is movable relative to the yoke. Two permanent magnets bear the core element. The permanent magnets are arranged relative to each other and to the yoke so that the reluctance transducer has a good linear relationship between displacement and force. The reluctance transducer can be applied as stiffness compensating element. The reluctance transducer can include an electrical winding to allow its application as a magnetic bearing, an actuator or as a displacement, velocity or acceleration sensor with improved intrinsic linearity.

A module includes a permanent magnet biased electromagnetic haptic engine having a stator and a rotor; a constraint coupled to the stator and the rotor; and a force sensor at least partially attached to the permanent magnet biased electromagnetic haptic engine and configured to sense a force applied to the rotor. The constraint is configured to constrain closure of a gap between the rotor and the stator and bias the rotor toward a rest position in which the rotor is separated from the stator by the gap.

An isomagnetic speaker comprising a diaphragm and an interference-free magnet structure is described herein. The interference-free magnet structure comprises a magnet array disposed to correspond with a predetermined region of the diaphragm and comprising a plurality of permanent magnets disposed at equal intervals along at least one direction. A plurality of bottoms of the plurality of permanent magnets are arranged on a same plane and oriented toward the diaphragm. A magnetic field direction of each permanent magnet is perpendicular to a corresponding bottom. A maximum size of a length of each permanent magnet along a direction parallel to the diaphragm is smaller than or equal to c/2f.sub.min, wherein c is a sound wave speed, and f.sub.min is a minimum output audio frequency of the isomagnetic speaker.

A laterally unconstrained magnetic joint has a first component comprising a permanent magnet material; and a second component comprising a permanent magnet or ferromagnetic material, where the first component and the second component are magnetically attracted to each other, and where the first component and the second component interface via continuous interface surfaces of different curvature that form and maintain point contact throughout a range of angular and lateral actuation. Movement of the first component is laterally unconstrained with respect to the second component. One or more such magnetic joints can be used in a mount for a payload, such as an wide angle optical mount with three degrees of freedom. The mount may include linear actuators to position the payload.