Abstract: A voice coil 6 is movably disposed in a magnetic gap 5. A drive cone (first diaphragm) 11 and a diaphragm (second diaphragm) 14 are integrally driven by the voice coil 6. Peripheral edge portion of the drive cone 11 and the diaphragm 14 are supported by a frame 12 through edge portions 13 and 15, respectively. An annular adhesive receiver 8 is disposed in a peripheral surface of a voice coil bobbin 7 around which the voice coil 6 is wound, and an inner peripheral edge 11a of the drive cone 11 is accommodated in the adhesive receiver 8. The drive cone 11, the adhesive receiver 8 and the voice coil bobbin 7 are connected to each other by an adhesive filled into the adhesive receiver 8.

Abstract: A loudspeaker in which the cone contains holes which allows the air behind the dust cover to flow freely in and out from behind the dust cover as the cone moves. There may also be a hole or holes in the lower suspension to allow air to escape from behind the lower suspension without ever becoming turbulent. All edges on the cone and basket are to be rounded as much as economically possible to prevent the air flow from becoming turbulent. The back of the speaker should be wrapped in a cloth like nylon tulle to prevent magnetic particles from getting into the magnetic structure causing speaker failure.

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 transducer for the creation of acoustic energy omni directionally in a horizontal plane. The transducer includes a base plate, the base plate supporting a centrally located voice coil motor assembly and a hemi-toroidal diaphragm having a proximal edge and a distal edge. The proximal edge is appended to the centrally located voice coil motor assembly and the distal edge is appended to the base plate.

Abstract: A speaker has an acoustic diaphragm, and an actuator that is driven based on an acoustic signal. The actuator has a transmission portion that is directly or indirectly attached to the acoustic diaphragm and transmits a displacement output of the actuator to the acoustic diaphragm. The actuator vibrates with the acoustic diaphragm by at least its component of the vibration along a plane of the acoustic diagram.

Abstract: A diaphragm (6) for an electroacoustic transducer is preferably designed to be essentially rectangular and has a diaphragm inner region (20) for sound conversion and a diaphragm outer region (21) for attaching the diaphragm (6) and a diaphragm intermediate region (22) which lies between the diaphragm inner region (20) and the diaphragm outer region (21), wherein the diaphragm inner region (20) is delimited toward the outside by preferably rectilinear sides (23, 24, 25, 26) and the diaphragm outer region (21) is delimited toward the inside again by preferably rectilinear sides (31, 32, 33, 34), and wherein the aforementioned sides (23, 24, 25, 26) of the diaphragm inner region (20) are joined to rounded outer corner regions (27, 28, 29, 30) with a mean outer radius value R and the aforementioned sides (31, 32, 33, 34) of the diaphragm outer region (21) are joined to rounded inner corner regions (35, 36, 37, 38) with a mean inner radius value r, wherein the mean inner radius value r of each inner corner region

Abstract: A loudspeaker diaphragm according to an embodiment of the present invention 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, wherein: the diaphragm portion includes, at an outer peripheral end thereof, an outer wall portion provided upright in a direction substantially parallel to a vibrating direction of the diaphragm portion; an inner peripheral surface of the edge portion is bonded onto an outer peripheral surface of the outer wall portion; and the outer wall portion has a height larger than a thickness of the diaphragm portion.

Abstract: A transducer including a frame and a panel disposed within the frame and coupled to the frame such that the panel may rotate relative to the frame about a rotational axis. The transducer includes an actuator positioned to engage the panel such that the panel rotates about the rotational axis.

Abstract: An electroacoustical transducer includes a bobbin, a first acoustic radiator coupled to the bobbin through a first surround having a mechanical compliance, a second acoustic radiator generally rigidly coupled to the bobbin, and a basket. The first acoustic radiator is coupled to the basket through a second surround, and the second acoustic radiator is coupled to the basket through a third surround. The first surround is constructed to cause the first acoustic radiator to move out of phase with the second acoustic radiator relative to the bobbin when actuated by the bobbin at acoustic frequencies at and above a resonant frequency of the first acoustic radiator.

Abstract: A method for reducing the radiation amplitude of material vibration modes (division vibrations) from a loudspeaker transducer diaphragm mechanically vibrated for the purpose of transforming an electrical signal into an acoustic signal. The diaphragm material may consist of formed paper or plastic sheet materials or molded paper pulp. The amplitude reduction of material vibration modes and pressure waves within the diaphragm material is accomplished by impressing small, shaped structures within the diaphragm material at critical locations determined by measurement with laser vibration analysis or position sensitive transient analysis of a loudspeaker transducer. The method is applied to the diaphragm material after it has been formed into the shape of a loudspeaker transducer diaphragm, either before or after the diaphragm has been assembled into a loudspeaker transducer.

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: An apparatus, the apparatus includes an electromagnetic signal device; a medium; and a sound wave generator. The sound wave generator includes a carbon nanotube structure. The carbon nanotube structure includes one or more carbon nanotube films. Each carbon nanotube film includes a plurality of carbon nanotubes substantially parallel to each other and joined side by side via van der Waals attractive force. The electromagnetic signal device transmits an electromagnetic signal to the carbon nanotube structure. The carbon nanotube structure converts the electromagnetic signal into heat. The heat transfers to the medium causing a thermoacoustic effect.

Abstract: A multifunctional transducer diaphragm may be configured as audio speaker system for displays wherein the multifunctional transducer diaphragm is capable of polarizing light transmitted therethrough and can convert mechanical motion into acoustical energy. In a related embodiment, a display panel system may comprise a multifunctional display screen comprising a single multifunctional transducer diaphragm capable of polarizing light which converts mechanical motion into acoustical energy, simultaneously providing both display screen and audio speaker functionalities.

Abstract: An improved structure of a speaker comprises a speaker frame disposed with a yoke at a lower end, the yoke is disposed with a magnet that is sleeved with a voice coil pipe; a lower damper is sleeved onto the voice coil pipe through a hole, with an outer edge of the damper attached to the outer edge of the bottom inside the speaker frame; a washer is overlapped at the outer edge of the lower damper, then an upper damper is sleeved onto the voice coil pipe through a hole, with its outer edge attached to the washer; two cones are hooked up and attached to each other with a hole of the two cones sleeved onto the voice coil pipe, and an outer edge of a cone surround is attached to a rim of the speaker frame to form the improved structure of the speaker.

Abstract: A high efficiency loudspeaker without a damper is provided. The loudspeaker includes magnetic circuit having a magnetic gap and a voice coil member, which has movable coil, disposed in the magnetic gap of the magnetic circuit. The loudspeaker also includes a diaphragm, whose inner peripheral part is linked with the voice coil member, outside the magnetic gap and a frame linked with an outer peripheral part of the diaphragm via a first edge. An inner peripheral part of a suspension holder is linked with the voice coil member at a linked position which is closer to the magnetic circuit than a linked position of the diaphragm and the voice coil member. An outer peripheral part of the suspension holder is linked with a frame via a second edge. The first edge and the second edge are substantially symmetrical with each other about a median of a first edge and a second edge.

Abstract: The present invention is to provide a loudspeaker, which includes a frame having a through hole centrally provided at a bottom side thereof, a coil tube with a coil unit fixedly mounted around the outer periphery thereof and having a first end fixed to the through hole and a second end received in a receiving space of the frame, a diaphragm attached to periphery of an opening of the frame, and a plurality of oppositely oriented magnetic elements fixed on the diaphragm, wherein every two adjacent magnetic elements are spaced apart by an appropriate distance, and the magnetic elements are located in the coil tube at positions that magnetic lines generated by the coil unit are highly concentrated. Since vibration of the magnetic elements caused by the magnetic forces generated from the coil unit is enhanced, output power of the loudspeaker will increase accordingly.

Abstract: A planar magnetic driver includes covering plates that are maintained under tension to form a buckled or curved surface, thereby providing for a larger magnetic gap, and allowing for a larger excursion of the diaphragm and extended lower frequency response. Another aspect of the driver includes a corrugated region along the periphery of the diaphragm, which provides increased internal dampening.

Abstract: A diaphragm of a speaker device, formed into an elongated configuration, has a recessed shape and includes a voice coil arrangement part extending in its longitude direction. The voice coil arrangement part has a gap with a constant width in its lateral direction and includes a voice coil supporting part for supporting a voice coil and an expanded part provided at a position along it.

Abstract: A speaker device includes a magnetic circuit which includes a magnetic gap, a diaphragm which has a recessed part arranged in the magnetic gap and extending in a direction substantially orthogonal with respect to an extending direction of a magnetic flux in the magnetic gap, and a voice coil which is formed into an annular shape and has a first parallel part extending in one direction and a second parallel part extending in a direction in parallel with the first parallel part and opposite to the first parallel part with a constant space. Particularly, the first parallel part and the second parallel part are arranged in a direction in parallel with an extending direction of the recessed part, respectively. The first parallel part is arranged in the recessed part to be positioned in the magnetic gap, and the second parallel part is positioned above the recessed part.

Abstract: A loudspeaker includes a diaphragm and an edge having an inner periphery end portion thereof connected with an outer periphery of the diaphragm, in which an outer end portion of the edge is attached to a speaker frame. The diaphragm has a bent portion in the vicinity of a border at the inner periphery side of a connecting portion connecting the diaphragm with the edge. A reinforcing portion is formed on the bent portion in order to reinforce the bent portion. It is, therefore, possible to disperse or reduce various forces applied to the bent portion, and to prevent strength deterioration or damage of the diaphragm even when sound signals having large amplitude are applied to the loudspeaker. As a result, it is also possible to prevent deterioration of acoustic characteristics.

Abstract: The membrane of a loudspeaker, which is driven on a limited part of the membrane, does not move completely like the tone current. For example, a cone, which is driven in the top, provides more accurate driving by also being driven in the periphery from the drive system back where the movement of the sound coil also is taken out. The driving can e.g. be distributed with a cone of net. With separate sound coils from the front side and back side of the driving system, the loudspeaker properties can be optimised. The biggest benefit is achieved with a long loudspeaker where the movement is taken out from the back side of the long drive system and distributed with plates, cones and wavy walls to a bulgy membrane edges.

Abstract: The present invention is directed to a condenser microphone with a microphone housing cap with a sound inlet opening, a microphone housing with a cross-sectional opening facing the microphone housing cap, and a diaphragm resting along the cross-sectional opening on the front side of the microphone housing surrounding the cross-sectional opening, and a counter-electrode which faces this diaphragm and which is arranged at a short distance from the diaphragm. The invention is further directed to a corresponding method for producing a condenser microphone of this kind. The invention provides an improved condenser microphone and an improved method for producing such a condenser microphone so that the disadvantages of the prior art are overcome while reducing manufacturing-related resources and, therefore, costs at the same time in that the diaphragm of the condenser microphone is glued to the microphone housing in an angle area between the underside of the diaphragm and the outer side of the microphone housing.

Abstract: A loudspeaker including a frame and a toroidal magnet that is affixed to the rear of the frame. The toroidal magnet has a central passageway that opens into the frame. A cap is affixed to the rear of the magnet and closes the central passageway. A guide rod is affixed to the cap and projects forwardly from the cap into the central passageway. A tubular former is slidably positioned upon the guide rod. A voice coil is wound about, and is affixed to, the tubular former. A driver plate is affixed to the front of the tubular former. A resilient surround connects the periphery of the driver plate to the front of the frame. A suspension assembly resiliently connects the tubular former to the frame and has a pair of conical diaphragms that are secured together so as to form a bellows. A spider connects the bellows to the frame and another spider connects the bellows to the tubular former.

Abstract: The present invention provides methods and apparatuses for an audio transducer. The audio transducer is excited by driving a paddle of a diaphragm. A plurality of node regions of a paddle is determined for the higher-order modal components, which correspond to resonance frequencies and have an order greater than one. An intersection region of at least two higher-order modal components is identified, in which an excitation point is located with the intersection region. The diaphragm of the audio transducer includes a frame, at least one hinge, and a paddle. The paddle connects to the frame by the at least one hinge and is excited by a signal source at an excitation point to produce an acoustic signal.

Abstract: A suspension member for a diaphragm, the suspension member comprising an inner portion being adapted to be attached to a substantially stiff piston part, a outer portion arranged on or integrated with a substantially stiff support member so as to mechanically stabilize the suspension member, and a flexible member connecting the inner and outer portions. The present invention further relates to an electro-acoustic transducer, preferably a miniature electro-acoustic transducer, applying such suspension member.

Abstract: Membrane construction for a loudspeaker, in particular a cone tweeter membrane construction, where said membrane comprises two concentrically arranged sections, a first inner dome shaped annular membrane section connected or integral with a second outer cone shaped membrane section, where the outer section comprises means for attaching a surround.

Abstract: A speaker diaphragm with a circular opening in a center zone thereof has a pattern of concave and convex sections formed on a front surface or a rear surface thereof. A plurality of concave and convex sections are formed in each of regions provided at a regular interval with a specific angle in a circumferential direction of the diaphragm. The concave and convex sections formed in each region have different sizes in a radial direction of the diaphragm. The concave and convex sections formed in adjacent regions are displaced from each other in the radial direction. The concave and convex sections formed on the diaphragm are aligned on at least a first and a second imaginary curved line, respectively, each imaginary curved line passing regions and approaching an inner periphery of the circular opening from an outer periphery of the diaphragm.

Abstract: A loudspeaker cone body made of plastic includes a base carrier material and a filler material. The base carrier material is selected to optimize overall flow, weight and stiffness. The filler material may be a nanomaterial that provides for adjustment of process and acoustic related characteristics in the loudspeaker cone body that become relevant when the loudspeaker cone body is operated in a loudspeaker. Acoustic related characteristics that may be adjusted include a stiffness to weight ratio and an acoustic damping of the loudspeaker cone body. A predetermined weight percent of the filler material may be combined with the base carrier material to obtain repeatable desired acoustic related characteristics. The acoustic related characteristics may be adjusted by changing the predetermined weight percent of the filler material.

Abstract: A planar diaphragm acoustic loudspeaker having a planar diaphragm biased with a high magnetic flux density magnetic circuit which feeds an acoustic waveguide. The apparatus provides high fidelity and efficient acoustic reproduction of high frequency alternating current signals with a minimum of diaphragm resonance and with a substantially flat electrical input impedance versus frequency. The diaphragm has a substantially uniform drive across an acoustically active portion and is held in three dimensional space whereby any mass or diaphragm resonances are controlled and minimized. The acoustic waveguide mates with said diaphragm and ensures a uniform acoustic phase field and an optimal diaphragm acoustic impedance match with atmosphere.

Abstract: A loudspeaker has a frame, a magnetic circuit, a voice coil body, a first edge, a diaphragm, a second edge, and a damper. The magnetic circuit is provided with a magnetic gap, and is supported by the frame. The voice coil body is disposed movably with respect to the magnetic gap. The outer peripheral end of the diaphragm is coupled to the frame via the first edge, and the inner peripheral end thereof is coupled to the voice coil body. The second edge is coupled to the frame at a position closer to the magnetic circuit than the first edge. The damper is disposed closer to the magnetic circuit than the diaphragm, the outer peripheral end thereof is coupled to the frame via the second edge, and the inner peripheral end thereof is coupled to the voice coil body.

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: An ultra low frequency transducer or subwoofer for automotive speaker systems with a rectangular or square or otherwise polygonal diaphragm. The basket of the transducer has a correspondingly polygonal front, which preferably is sized to be substantially coextensive with the front of the speaker housing or cabinet. In this way, air displacement in the subwoofer is maximized for a given size of enclosure, and thus so is the loudness of the speaker. The preferred diaphragm is concave, and the transducer preferably includes a convex surround with pleated corners. For increased durability, trusses are formed in the diaphragm.

Abstract: An acoustic device comprising a diaphragm (10) having an area and having an operating frequency range and the diaphragm (10) being such that it has resonant modes in the operating frequency range, an electromechanical transducer having a drive part coupled to the diaphragm (10) and adapted to exchange energy with the diaphragm, and at least one mechanical impedance means (20,22,24) coupled to or integral with the diaphragm, the positioning and mass of the drive part (26) of the transducer and of the at least one mechanical impedance means (20,22,24) being such that the net transverse modal velocity over the area of the diaphragm (10) tends to zero.

Abstract: A suspension member for a diaphragm, the suspension member comprising a first portion being adapted to be coupled to a substantially stiff piston part, a second portion integrated with a substantially stiff support member suitable for acoustic sealing purposes, and a flexible member connecting the first and second portions.

Abstract: A speaker includes a speaker body; a cone paper movably supported by the speaker body; and a magnetic driving unit disposed on the speaker body to vibrate the cone paper, wherein the cone paper includes at least two layers made of different materials.

Abstract: A curve fitted planar loudspeaker minimizes variation and dead zones in the sound field propagated by an array of the loudspeakers. The curve fitted loudspeaker provides a plurality of sound generating transducers. The diaphragm is curved and each adjacent section fits as a section into a larger curve, eliminating or minimizing breaks in the propagated sound filed at the target distance to the target.

Abstract: A speaker is disclosed in which a split resonance of a diaphragm main body and a natural resonance of an edge are controlled, achieving a high sound quality while realizing a weight reduction. A diaphragm is composed of a diaphragm main body and an edge. An outer peripheral part of the diaphragm main body is bonded with a peripheral edge of a frame through the edge. An external shape of edge is formed in substantially a perfect circle. While, at least one of the outer peripheral part of the diaphragm main body and an inner peripheral part of the edge, which is a mutual bonding portion, is formed in a different shape than the perfect circle.

Abstract: A loudspeaker includes a circular damper, a cone, and a cylindrical bobbin. The circular damper may include a centrally disposed cone attachment protuberance and a peripherally disposed top plate attachment section. The cone may have a central inner portion that may be attached to the cone attachment protuberance of the damper. The cone may be attached to the cylindrical bobbin, which may have a voice coil coupled thereto.

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: An ultrasonic transducer includes: a fixed electrode having corrugations on the surface; a vibrating film having an electrode layer and disposed on the surface of the fixed electrode; and a holding member which holds the fixed electrode and the vibrating film. The ultrasonic transducer is driven by applying an AC signal between the electrode layer of the vibrating film and the fixed electrode, and generates a sound pressure of at least 120 dB within a frequency range from 20 kHz to 120 kHz.

Abstract: A speaker includes an elongated diaphragm and a coupling member including forward and rearward segments, wherein at least two protrusions are provided at the rear side of the diaphragm along the major axis direction, the forward segment is engagingly disposed between the opposing end faces of two adjacent protrusions and also between the two portions of a rib of the diaphragm opposing each other in the minor axis direction, and wherein the outer circumferential surface of the voice coil bobbin is connected to the inner circumferential surface of the rearward segment, whereby the voice coil bobbin having a diameter larger than the dimension of the diaphragm measured along the minor axis direction can be successfully attached to the diaphragm. In the speaker described above, the diameter of the voice coil bobbin can be increased without decreasing the width of a surround thus enabling the withstanding of higher power input.

Abstract: A membrane for an electroacoustic transducer is disclosed having a first area, a second area, which is arranged for translatory movement in relation to said first area, and a third area, which connects said first area and said second area, wherein local, planar spring constants along a closed line within said third area encompassing said second area, are determined in such a way that local, translatory spring constants along said line in a direction of said translatory movement are substantially constant or exclusively have substantially flat, mutual changes.

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: According to the invention, a whole-surface driven, flat thin loudspeaker that brings about smooth frequency characteristics with split vibration hardly caused is realized, and a voice coil assembly that has high reproduction efficiency and fewer operation failures, and brings about favorable work efficiency in manufacturing and further reduced manufacturing cost, and a loudspeaker using the same are manufactured.

Abstract: An acoustic assembly for use in a transducer includes a multi-layer structure. A first layer member includes a first center portion, a first edge portion and a first aperture separating the first center portion and the first edge portion. A second layer member includes a second center portion, a second edge portion and a second aperture separating the second center portion and the second edge portion such that the second center portion is free to move relative to the second edge portion. The first and second layers are formed into an assembly wherein the first center portion and the second center portion are coupled, the first edge portion and the second edge portion are coupled, and the first aperture and the second aperture are substantially aligned to define a passageway. The assembly has an assembly stiffness that is greater than the stiffness of either the first or second layer members.

Abstract: The design of a diaphragm for a rotary loudspeaker driver that eliminates phase cancellation and therefore eliminates the necessity of a box to acoustically isolate the front sound from the back. The key element of the design of the diaphragm is to use a cross section of at least three equal sides. This allows for the long sides of the diaphragm to create essentially positive pressure only as it rotates and creates a very rigid structure. Further by sizing the cross section to the width of the highest frequency to be produced you allow for a nearly perfect 360 degree radiation at all frequencies.

Abstract: An acoustic diaphragm includes a diaphragm formed of a uniform material and a first standing wave suppression member provided on a surface of the diaphragm along a first direction of passing through a center of the diaphragm.

Abstract: An ultrasonic transducer includes: a diaphragm pot that has a surrounding wall; a transducer element mounted in a diaphragm pot on a transducer section on an inner side of the diaphragm for generating the ultrasonic vibrations; a first damping element situated in the diaphragm pot on transducer element for damping the diaphragm; and a second damping element situated within the diaphragm pot in an edge section of the diaphragm around the transducer element for damping vibrations of the wall; the second damping element being connected with force locking, at least section by section, both to the edge section and to the inner side of the wall.

Abstract: A loudspeaker may include a baffle, a planar diaphragm transducer carried by the baffle and having a front surface for radiating acoustic energy therefrom, and a slotted waveguide adjacent the front surface of the planar diaphragm transducer. The planar diaphragm transducer may be operable to a desired high frequency, and the slotted opening may have a width not substantially greater than a wavelength corresponding to the desired high frequency. For example, for a desired high frequency of about 20 KHz, the slotted opening may have a width not greater than about two-thirds of an inch. Accordingly, the loudspeaker including the slotted waveguide may provide nearly constant horizontal directivity over a large angle. In another embodiment, the loudspeaker may include a conical diaphragm transducer with a slotted waveguide adjacent its front surface.

Abstract: The loudspeaker includes a dome diaphragm that is made of a base material impregnated in a thermosetting resin; a cone diaphragm whose outer circumference side end portion is coupled with an outer circumference end portion of the dome diaphragm; and a voice coil having a bobbin whose one end is coupled to a back surface of the dome diaphragm, and whose outer curved surface is coupled with an inner circumference end portion of the cone diaphragm, wherein the dome diaphragm is provided with a plurality of cone-shaped projections that is formed by hardening the thermosetting resin, projecting from the back surface, and disposed in a circular pattern with a space between each other, the plurality of cone-shaped projections defining a coupling portion to which the one end of the bobbin is coupled.