Abstract: A loudspeaker for active noise cancellation is disclosed in which a measurement microphone (12) is arranged at the acoustic center. In addition, a system for active noise cancellation is described.

Abstract: Each of a speaker diaphragm, a dust cap, and a frame includes a resin and a plant opal that is extracted from a bamboo leaf, and is formed by injection molding or sheet molding. The configuration can enhance stiffness of each of the diaphragm, the dust cap, and the frame and implement high performance.

Abstract: A linear interleaved magnetic motor in which the B-field flows between a plurality of motor cell elements, creating a long, serpentine gap. The motor is used with at least one flex circuit as a drive coil. The motor can be used as a drive motor for a loudspeaker transducer. Multiple loudspeaker transducers can be connected together to make a loudspeaker frame or system.

Abstract: A slimline speaker comprises: a magnetic circuit having a magnet and yoke disposed to form a separating space in the horizontal direction; a bobbin on which a voice coil is mounted and of which the lower side is inserted in the separating space between the magnet and yoke; a base frame for mounting the magnetic circuit; a damper having an inside edge coupled to the bobbin and an outside edge coupled to the base frame; and a diaphragm having an inside edge coupled to a point lower down than the point where the damper is coupled on the bobbin, and an outside edge coupled to the base frame.

Abstract: A speaker diaphragm (2), and plural dimples (16) which are disposed radially from a center side toward the outside of the speaker diaphragm (2) and which have arch structures formed to have a concave-like shapes so as to disperse a stress are provided, whereby while weight saving is realized in terms of the speaker diaphragm (2) by the plural dimples (16) formed to have the concave-like shapes, high rigidity is maintained by the arch structures of the dimples concerned, and a maximum sound pressure can be increased along with the weight saving concerned.

Abstract: A speaker. The speaker includes a housing, a first electrode, a second electrode, and a diaphragm. The housing has a first end, the first end which includes an acoustic aperture. The first electrode is positioned in the housing a first distance from the first end, and is biased to a first voltage. The second electrode is positioned in the housing a second distance, which is greater than the first distance, from the first end. The second electrode is biased to a second voltage. The diaphragm is positioned in the housing between the first electrode and the second electrode, and is biased to a third voltage. The speaker includes a valve. The valve opens when the diaphragm is moving away from the first end and closes when the diaphragm is stationary or moving toward the first end. When the valve is closed, the diaphragm forms an air-tight seal between the first end and the second electrode.

Abstract: The present invention allows for the further enhancement of a low pitch range with a simple structure without increasing the size. The present invention is provided with: a pipe (102) open one end side and the other end side; a speaker unit (104) that is coaxial with the pipe (102), arranged at the one end side of the pipe (102), and driven on the basis of an audio signal; and an edge-cum-diaphragm (102B) that is coaxial with the pipe (102), installed at the other end side of the pipe (102), and vibrates in response to a sound wave that passes through the pipe (102). While the pipe (102) functions as a resonance tube by being excited to vibration with the sound wave that is radiated from the speaker unit (104) and passes through the pipe (102), the edge-cum-diaphragm (102B) functions as a passive radiator by vibrating in response to the sound wave that passes through the pipe (102).

Abstract: There is provided a dynamic sound transducer having a diaphragm system (10) which has at least a first and second metallized surface (11) which are separated from each other by an insulating surface (12). The dynamic sound transducer further has a moving coil (20) with a coil wire (25). An end of the coil wire is electrically conductingly connected to the first metallized surface (11) and the other end of the coil wire is electrically conductingly connected to the second metallized surface (11).

Abstract: An electromagnetic device includes a housing, a planar coil disposed inside the housing, and a magnetic diaphragm disposed inside the housing, wherein the plane of the planar coil is substantially in parallel with the plane of the magnetic diaphragm, wherein the planar coil is separated from the magnetic diaphragm, and wherein the magnetic diaphragm is moveable in the presence of an exterior pressure.

Abstract: A speaker diaphragm includes a body vibrating to generate a sound, an edge fusion-bonded to an outer circumference portion of the body, a projection provided on an upper surface of the edge, and a gasket provided on a lower surface of the edge. The edge is made of material different from that of the body. The projection is made of material identical to that of the edge. The gasket is made of material identical to that of the body. A speaker including the diaphragm has waterproof property by itself.

Abstract: A system and methods for implementing substantially triangular or trapezoidal speaker enclosures and related components. A speaker enclosure may be shaped substantially as an equilateral triangle, loaded with three speakers mounted radially equidistant from the planar center of the triangular enclosure. The speaker enclosure may comprise a triangular port with a detachable lid. A speaker enclosure also may be shaped substantially as a box with an interior triangular subchamber. The speaker enclosures may further include an amplifier system having a novel input gain stage or a novel tone stack, or both. An amplifier system also may comprise parallel audio input processing through input gain modules and tone stack modules, with the separate audio signals summed by a novel mixdown module.

Abstract: A speaker and the like, which is capable of wideband reproduction by improving the bass characteristic, and which is suitable for size reduction, is provided. A housing (110) includes one main surface (111) having a polygonal shape, and an opening portion (112) in the one main surface. A diaphragm (120) is disposed in the opening portion so as to cover the one main surface, except for corner regions (115a, 115b, 115c, and 115d) which are areas in the vicinity of respective vertices of a polygonal shape of the one main surface. A driving unit (130) causes the diaphragm to vibrate so as to generate a sound corresponding to a signal inputted from an outside. A plurality of movable supports (140a, 140b, 140c, and 140d) is disposed in the respective corner regions, for supporting the diaphragm by joining the housing and the diaphragm such that the diaphragm is vibratable.

Abstract: A loudspeaker designed with a large area having sandwich-like layer structure includes a plurality of conductive and nonconductive layers which form an active sound-radiating loudspeaker surface. The plurality of conductive and nonconductive layers include a first diaphragm sheet coated with an electrically conductive layer, a second diaphragm sheet coated with an electrically conductive layer, a static high-voltage supply, which generates an electric field between the first electrically conductive layer and the second electrically conductive layer, and an audio source which influences the high-voltage fields between the first electrically conductive layer and the second electrically conductive layer via a capacitor. The invention is distinguished in that, with the second electrically conductively coated diaphragm sheet, the first electrically conductively coated diaphragm sheet forms a sandwich which extends simply over the active loudspeaker surface, around a first elastic and nonconductive interlayer.

Abstract: A sound transducer structure includes a membrane, a counter electrode, and a plurality of elevations. The membrane includes a first main surface, made of a membrane material, in a sound transducing region and an edge region of the membrane. The counter electrode is made of counter electrode material, and includes a second main surface arranged in parallel to the first main surface of the membrane on a side of a free volume opposite the first main surface of the membrane. The plurality of elevations extend in the sound transducing region from the second main surface of the counter electrode into the free volume.

Abstract: A loudspeaker driver (22) also suitable for compound applications comprising a rigid speaker frame (11, 13, 15, 19, 8) to which is attached a permanent magnet (13) with which a voice coil winding (9) is adapted to interact through electromagnetic force. The voice coil winding (9) is adapted to deliver axial motion to a diaphragm assembly (21), which includes an elastic outer section (2), whose outer rim (5) is attached to the outer part of the speaker frame (11). The diaphragm assembly (21) comprises an essentially rigid primary vibrating diaphragm (4) attached between the elastic outer section (2) and an elastic inner section (3), whose inner rim (10) is attached to the inner part of said speaker frame (8). Said voice coil winding (9) is fixed to the primary vibrating diaphragm (4) through said voice coil former (6), which is adapted to move said diaphragm assembly (21).

Abstract: In a diaphragm of an electric sound converter which converts vibration such as sound into an electrical signal, a center dome is reinforced while suppressing variations in the sensitivity and frequency response to the minimum, whereby reduction in a high-pass reproduction limit is suppressed, and occurrence of anomalous resonance is prevented. In a diaphragm 1 of an electric sound converter having a center dome 2, a reinforcing film 7 made of the same material as that of the center dome and formed into the same shape as that of the center dome is applied to the center dome with a hot-melt adhesive 6 of the same nature as that of the center dome, a groove 7a formed in a polygonal reticulate pattern is provided on one surface of the reinforcing film adhered with the adhesive, and a convex rib 8 corresponding to the groove is formed on the other surface.

Abstract: A device for emitting an acoustic wave includes a flared structural piece bearing at its base an electromechanical transducer and defining at its flared end an output surface. A mechano-acoustic coupler made of one piece is a solid piece and exhibits: a first portion for mounting on the transducer, a second portion extending from the first portion up to the level of the output surface, the coupler being suspended on the structural piece at the level of the second portion and the second portion having a cross-sectional area at the level of the output surface which is strictly greater than its cross-sectional area at the level of the first portion, and a third portion extending from the second portion, where the third portion has a cross-sectional area which is smaller than the output surface, the third portion including a cross-section of greater area than the output surface.

Abstract: A method and apparatus for pneumatically sealing an acoustic radiator to an acoustic enclosure. A band of conformable material engages a beveled surface so than an edge of the band deflects outwardly and a surface of the band conforms to the beveled surface.

Abstract: A loudspeaker 2 comprises a dome 16 whose edge is stiffened by a carbon fiber ring 20. The dome 16 is shaped as a catenary or parabola.

Abstract: An electrostatic speaker including a frame; a first electrode installed at a first end of the frame; a second electrode installed at a second end of the frame to be at a predetermined distance apart from the first electrode; a suspension which is arranged between the second electrode and the first electrode and is elastically installed inside the frame; and a diaphragm assembly which is supported by the suspension and has a multilayer structure. The electrostatic speaker adopts a dual electrode structure, has the multilayer structure formed inside the diaphragm assembly, and is provided with a driving chip that applies a bias voltage to the diaphragm assembly by rectifying an audio signal after applying a driving signal that has amplified the audio signal to the dual electrodes. Thus, the invention does not require any external power, and is also capable of maintaining relatively high sensitivity by enhancing the charge density.

Abstract: A rigid, flat plate diaphragm for an acoustic device is illustrated. The internal supporting structure of the diaphragm provides a combination of torsional and translational stiffeners, which resemble a number of crossbars. These stiffeners brace and support the diaphragm motion, thus causing its response to not be adversely affected by fabrication stresses and causing it to be very similar in dynamic response to an ideal flat plate operating in a frequency range that extends well beyond the audible.

Abstract: A speaker device includes: an acoustic diaphragm having a given shape and made of a material having physical anisotropy; and an excitation means attached to the acoustic diaphragm for exciting vibration components in consideration of a direction corresponding to the physical anisotropy.

Abstract: A speaker. The speaker includes a housing, a first electrode, a second electrode, and a diaphragm. The housing has a first end, the first end which includes an acoustic aperture. The first electrode is positioned in the housing a first distance from the first end, and is biased to a first voltage. The second electrode is positioned in the housing a second distance, which is greater than the first distance, from the first end. The second electrode is biased to a second voltage. The diaphragm is positioned in the housing between the first electrode and the second electrode, and is biased to a third voltage. The speaker includes a valve. The valve opens when the diaphragm is moving away from the first end and closes when the diaphragm is stationary or moving toward the first end. When the valve is closed, the diaphragm forms an air-tight seal between the first end and the second electrode.

Abstract: A MEMS acoustic transducer, for example, a microphone, includes a substrate provided with a cavity, a supporting structure, fixed to the substrate, a membrane having a perimetral edge and a centroid, suspended above the cavity and fixed to the substrate the membrane configured to oscillate via the supporting structure. The supporting structure includes a plurality of anchorage elements fixed to the membrane, and each anchorage element is coupled to a respective portion of the membrane between the centroid and the perimetral edge of the membrane.

Abstract: A loudspeaker diaphragm includes a diaphragm portion and an edge portion, which is molded integrally with the diaphragm portion and made of a material different from a material for the diaphragm portion. The edge portion contains at least one thermoplastic polymer (I), in combination with a block polymer (II). The at least one thermoplastic polymer (I) is selected from a block copolymer (I-a) which contains a polymer block (A) having a repeating structural unit derived from an aromatic vinyl compound and a polymer block (B) having a repeating structural unit derived from a conjugated diene, and an addition hydrogenated block copolymer (I-b) of the block copolymer (I-a). The block copolymer (II) contains a polymer block (C) having a repeating structural unit derived from an olefin compound and a polymer block (D) having a repeating structural unit derived from a (meth)acrylic compound.

Abstract: An electromechanical transducer 180, motor structure 200 and voice coil winding support structure or bobbin 210 are configured to protect and transport heat away from a voice coil 220 which is would solely within the interior of bobbin 210 and configured for reciprocating movement in close proximity to an extended cooling pole piece 204. A compact, economical and efficient adaptation of a pancake style motor includes generous volume for a powerful magnet 208, while providing an extended, linear range of excursion and continuous cooling for the generously overhung voice coil 220.

Abstract: A diaphragm is provided with a plurality of thick portions radially from an inner circumferential side to an outer circumferential side. The thick portions are composed of at least two kinds having different lengths in a radiation direction and formed to be gradually thinner in the radiation direction from the inner circumferential side to the outer circumferential side. With this configuration, separate vibrations in the diaphragm can be suppressed. Further, a speaker device provided with the diaphragm having the above-described configuration can reproduce sounds faithfully in accordance with input signals.

Abstract: The present invention relates to a capacitor microphone unit including a diaphragm, a fixed electrode that is arranged opposite to the diaphragm with a space provided between the diaphragm and the fixed electrode so that a capacitor is formed between the diaphragm and the fixed electrode, an insulating base that is disposed on a rear side of the fixed electrode and supports the fixed electrode, and a ring-shaped acoustic resistance material that is disposed on a front side of the insulating base, all of which are incorporated in a unit casing. A skin layer is formed on at least one of a front side and a rear side of the acoustic resistance material, and the skin layer has a higher density than that inside the acoustic resistance material, whereby acoustic resistance can be readily controlled.

Abstract: Ring-shaped membrane for an electro-acoustical loudspeaker, where said membrane comprises two or more dome-shaped annulus concentrically arranged around a central portion through which an imaginary axis of symmetry passes, where an outer periphery of said membrane is suitable to be attached to a surround; where the central portion is attached to a tower, which again is fastened to the loudspeakers driver, wherein the angle between a plane being perpendicular to the axis of symmetry and the attachment of the membrane to the surround resp. the tower is in the interval 0° to 40°, most preferred around 30°.

Abstract: A loudspeaker diaphragm made by preparing a fabric from a hybrid yarn, wherein the hybrid yarn includes a matrix component and a reinforcement component. The matrix component may include a first material selected from a group consisting of a polyamide, a polyphenylene sulfide, and a polyetheretherketone, and the reinforcement component may include a second material selected from a group consisting of carbon and a para-aramid. The fabric may be introduced into a mold and molded to form a loudspeaker diaphragm. The fabric may then be heated to a temperature higher than the melting temperature of the polyamide or polyphenylene sulfide or polyetheretherketone, so that the polyamide or polyphenylene sulfide or polyetheretherketone melts.

Abstract: An edge portion includes a center portion, one end and an other end. As seen in a cross section of a vibration plate in the radial direction, the center portion, the one end and the other end each are formed in a circular arc such that the edge portion forms a convex so as to protrude in a direction in which the protruding shape protrudes. The radius of curvature of the circular arc of the center portion is not less than the radius of curvature of the circular arc of each of the one end and the other end. Accordingly, a vibration plate allowing a decrease in the lowest resonance frequency while suppressing the edge portion from being brought into a tensioned state, a speaker unit provided with the vibration plate and a portable information terminal can be provided.

Abstract: A flat thin dynamic speaker which includes a motor unit, a suspension unit, a radiating unit and a frame arranged in such a manner that the motor unit and the suspension unit are at the same plane while the radiating unit is on top of the motor unit such that the thickness of the speaker assembly is reduced while the performance of the speaker assembly is maintained or even improved. Also, the speaker can be made into a quadrangular, polygon or a spherical structure. The speaker further has a surround at a level lower than the radiating unit without utilizing the radiating surface of the radiating unit such as a maximized radiating surface is provided, and includes a dual side voice-coil actuation to the radiator unit, thereby providing a slim and flat speaker assembly with high power output.

Abstract: Systems and apparatuses are provided for vibration confinement and stress management in a loudspeaker. In one embodiment, the loudspeaker comprises a diaphragm that extends from an inner diaphragm region (e.g., dome or cone-shaped) to an outer diaphragm region, wherein the outer diaphragm region bends at a defined angle (e.g., between about 45 degrees and about 135 degrees) relative to the inner diaphragm region. The loudspeaker also comprises a suspension member extending from an inner suspension region to an outer suspension region, the inner suspension region overlapping and attaching with the outer diaphragm region. The bend in the diaphragm isolates the inner diaphragm region from spurious vibrations in the suspension member.

Abstract: The present invention provides a dome-shaped diaphragm fabricated based on a film base of polyethylene terephthalate resin film. The diaphragm includes a first vibrating part of a dome shape or a flat shape, and a second vibrating part of an annular shape. The second vibrating part includes a peripheral portion of the film base provided around a central portion of the film base. The first vibrating part includes the central portion of the film base, a thermosensitive adhesive resin film, provided on the central portion, and a fiber sheet made of a woven fabric using carbon fiber or an embossed nonwoven fabric. The fiber sheet is layered over the central portion with the thermosensitive adhesive resin film interposed therebetween.

Abstract: A membrane 103 for an acoustic device 100 is provided, the membrane 103, wherein the membrane 103 comprises a central portion 212, an annular portion 105, and a corrugation 107, wherein the annular portion 105 is arranged around the central portion 212, wherein the annular portion 105 is adapted to be fixed to a coil 106, and wherein the corrugation 107 is arranged between the central portion 212 and the annular portion 105. Thus, the corrugation 107 may form an inner corrugation compared to an outer corrugation 104 which would be arranged farther away from the central portion 212 than the annular portion 105.

Abstract: An ultra-thin loudspeaker structure comprises an upper drum paper, a lower drum paper, and a steel sheet. The lower drum paper defines an opening at a center thereof and is integrally formed with a surrounding raised paper section near a periphery thereof. The upper drum paper defines an opening, corresponding to the opening of the lower drum paper, at a center thereof. The upper drum paper is located within the surrounding raised paper section and adhered to the lower drum paper by its periphery. The steel sheet is provided with a sound-making member stacked by a plurality of ceramic material layer, and is sandwiched between the drum papers. Accordingly, the steel sheet can facilitate spreading sound of high and medium frequency whereas the drum papers can facilitate spreading sound of low frequency, to achieve a better reproduction of sound.

Abstract: A slim speaker includes a casing having an enlarged front opening and a rear end with a magnetic circuit mounted thereto; a voice coil located over a central area of the magnetic circuit; a diaphragm located between the enlarged front opening of the casing and the voice coil; and a damper located behind the diaphragm to space from the latter. The diaphragm has at least one V-shaped bent section provided at a middle portion for bearing on a corresponding position on the damper. With these arrangements, the diaphragm not only has an effectively reduced overall height to largely reduce the assembled volume of the slim speaker and allow the slim speaker to be easily mounted in the limited inner space of an electric product, but also stabilizes the vibration of the voice coil to enable good resonance of sound.

Abstract: A speaker has high sound quality by reducing resonance of curved parts in a speaker damper without decreasing sound pressure and by providing high linearity characteristic. In a damper for a speaker formed by including at least two curved parts, an elastic member is provided at least on one side or on both sides of a peripheral part in a movable part of the damper or provided in the material.

Abstract: An improved mid to high-frequency loudspeaker of the type having a central dome diaphragm having an outer periphery, and in one embodiment an outer ring-radiator diaphragm portion defining an inner periphery and an outer periphery, the ring-radiator diaphragm being attached at its inner periphery to an armature voice coil assembly and at its outer periphery to a diaphragm chassis in a first plane.

Abstract: The present invention provides: a loudspeaker including a frame, a drive unit, and a membrane; the membrane having an inner edge, an outer edge which is suspended from the frame, and a membrane body which is between the inner and outer edges and extends around the drive unit; the drive unit having a stationary part secured to the frame and a translatable part secured to the inner edge of the membrane; the membrane body including a dished portion which, has a depth that increases from said inner and outer edges towards a base region of the dished portion located between said edges; wherein the loudspeaker includes a stiffening element which extends around the drive unit and stiffens the membrane body at the base region of the dished portion, so as to reinforce the membrane against deformation in the base region. By including the stiffening element, it has been found that the first break-up resonance of the membrane is shifted to a higher frequency and has reduced amplitude.

Abstract: A transducer generates acoustic energy. The transducer is suitable for incorporation into any device that needs sound reproduction capability, including devices with generally rectangular geometries such as cell phones, PDAs, and portable gaming devices. The transducer includes a displaceable membrane with a deformable corner. The deformable corner may extend the frequency range over which the transducer generates acoustic energy without distortion. The deformable corner may be part of a membrane periphery around the displaceable membrane. The membrane periphery may be square, triangular, or may take any other polygonal shape.

Abstract: A diaphragm includes a central portion and an edge portion around the central portion. The central portion includes a plurality of carbon nanotubes therein. The central portion is a carbon nanotube structure or a carbon nanotube composite structure. A loudspeaker using the diaphragm is also disclosed. The loudspeaker includes the diaphragm and a voice coil connected to the diaphragm. The voice coil is connected to an outer periphery of the central portion or a joint portion between the central portion and the edge portion.

Abstract: An electroacoustic transducer includes a frame defining a hollow space, and an elastic member mounted on the frame. The elastic member includes a circular plane lamina and a plurality of elastic arms extending outwardly from a circumference of the circular plane lamina. A diaphragm includes a vibrating film mounted with the circular plane lamina, and an edge damper integrally formed with an outer periphery of the vibrating film. A voice coil is attached below the vibrating film and electrically connected to the circular plane lamina. At least two through holes are formed between an outer periphery of the circular plane lamina and an inner side of the voice coil for balancing the air pressure of the air below the diaphragm.

Abstract: A diaphragm includes carbon nanotube wire structures. The carbon nanotube wire structures are crossed with each other and woven together to form the diaphragm with a sheet structure. Each of the carbon nanotube wire structures includes carbon nanotube wires substantially parallel to each other, and closely arranged along an axis of the carbon nanotube wire structure to form a bundle-like structure, or carbon nanotube wires twisted with each other around an axis of the carbon nanotube wire structure in a helical manner to form a twisted structure. A loudspeaker using the diaphragm is also disclosed.

Abstract: A microelectromechanical system microphone package structure includes a base plate and a plurality of chips is provided. The plurality of chips are disposed on the base plate, wherein an active area of each of the chips is disposed with a microelectromechanical system microphone structure, each of the active areas comprises a normal line, and the normal lines of the chips are unparallel and nonorthogonal to each other.

Abstract: The adsorption stability with respect to a fixed pole is increased while the low frequency response of a diaphragm is improved especially in an electret condenser microphone. In a diaphragm 11 for a condenser microphone, which is formed of a thermoplastic resin film having a metal film on one surface thereof, a first irregularity pattern 12 consisting of rough irregularities 12a having a long period and a second irregularity pattern 13 consisting of fine irregularities 13a having a short period are formed over the whole region of the diaphragm 11.

Abstract: A W-shaped radiating surface for a transducer assembly is described. The radiating surface has a center portion and an outer portion. The center portion is disposed in the center of a voice coil former and has a first sloping region and a second sloping region that meet at a first angle. The outer portion is disposed outside the center of the voice coil former and has a third sloping region and a fourth sloping region, which meet at a second angle. The center portion couples with the outer portion at a third angle to form a radiating surface that has a W-shaped cross section.

Abstract: A magnetic circuit includes a cylindrical yoke member having an inner circumferential surface and a collar formed at one end thereof and turned back substantially at right angles, and a plurality of permanent magnet segments of a partially circular arc in cross section. Each of the permanent magnets has an outer surface attracted magnetically to the inner circumferential surface of the cylindrical yoke member, and one end face attracted magnetically to the collar of the cylindrical yoke member. The magnetic circuit is applied to an actuator or a speaker.

Abstract: In a speaker, a first space enclosed by the surface of a second edge close to a magnetic circuit body, a suspension holder, the outer circumferential surface of a voice coil body, the magnetic circuit body, and a frame is airtight to the atmosphere outside the speaker, to make a first space function as an air suspension. The voice coil body is supported with a first edge and a second edge, and with the aid of the springiness of gas inside a first space. Hence, an equivalent, low Young's modulus can be set to the first edge and the second. Consequently, deformation of the diaphragm connected to the first edge is reduced during sound reproduction, thereby reducing disturbance in frequency response in the middle and high ranges.

Abstract: A method for manufacturing a ferrite magnet device including a ferrite body and first and second center electrodes arranged so as to intersect and be electrically insulated from each other and a permanent magnet arranged to apply a direct current magnetic field to the ferrite body and a method for manufacturing an isolator or a composite electronic component, which include the ferrite magnet device. A magnetic force of the permanent magnet is adjusted using a measurement jig and a magnetic force adjusting apparatus while the permanent magnet is fixed to a principal surface of the ferrite body.