Abstract: A drive signal generating unit generates a drive signal having a cyclic waveform containing a zero period in a vibration mode. A driver unit generates the drive current in response to the drive signal generated by the drive signal generating unit so as to supply the drive current to a voice coil. An induced voltage detector detects the induced voltage occurring in the voice coil during a nonconducting period. A zero-cross detector detects the zero cross of the induced voltage detected by the induced voltage detector. The drive signal generating unit estimates the eigen-frequency of a vibration speaker from a detected position of the zero cross and brings the frequency of the drive signal close to the estimated eigen-frequency.

Abstract: According to an aspect of the invention, there is provided a speaker apparatus including: a speaker frame; and a connection terminal for electrically connecting to an outside of a speaker, an axis line of the connection terminal being arranged along a tangential line direction of a circumference of the speaker, the connection terminal being not projected to an outer side in a diameter direction of the speaker from the speaker frame.

Abstract: The present invention discloses a spring reverberator and an assembling method thereof, in which the spring reverberator comprises: a casing, a driving transducer received in the casing, a pickup transducer received in the casing, and coil springs vibratingly coupled to the driving and pickup transducers. The driving and pickup transducers respectively include a vibration unit and a magnetic core. The vibration unit comprises a support plate including at least one cut-out groove, through which a wire is soldered directly to the support plate. The vibration unit and the magnetic core are prepared in a modular type to be inserted in a sliding manner and fixed in the casing.

Abstract: To provide a thin speaker device a voice coil itself is made thin and vibration of the voice coil is efficiently transmitted to a diaphragm. The voice coil is used for a speaker device in which the vibration in one axial direction of the voice coil is transmitted to the diaphragm via a rigid vibration direction converter part, and the diaphragm is vibrated in a direction different from the one axial direction. The voice coil is formed with planarly and annularly wound conducting member and has rigidity at least in the vibration direction along the planar direction.

Abstract: The present invention provides a magnet assembly and speaker including such a magnet assembly. The magnet assembly includes an outer magnet defining a pair of first plat magnets, an inner magnet surrounded by the outer magnet and defining a pair of second plat magnets, a first magnetic gap formed between an inner surface of the outer magnet and an outer surface of the inner magnet, and a magnetic conductive portion sandwiched between the pair of the second plat magnets. A width of the magnetic conductive portion is unequal to a length of the outer and inner magnets. Polarity of the pair of the first plate magnets adjacent to the magnetic gap is similar to each other. Polarity of the pair of the first plate magnets adjacent to the magnetic gap are opposite to that of the pair of the second plate magnets adjacent to the first magnetic gap.

Abstract: A flat speaker device capable of emitting loud reproduced sound with a relatively simple configuration is provided. The speaker device includes a diaphragm, a frame supporting the diaphragm vibratably in the vibration direction, a magnetic circuit disposed in the frame, and a driving member for driving the diaphragm. The driving member includes a voice coil movably disposed in a magnetic gap of the magnetic circuit, a driving part formed movably in a direction different from the vibration direction of the diaphragm, and an angle conversion and transmission part, one end of which is angle-variably joined to the driving part and another end of which is angle-variably joined to the diaphragm. The angle conversion and transmission part has rigidity and is obliquely disposed with respect to each of the vibration direction of the diaphragm and the moving direction of the driving part.

Abstract: An electromagnetic ultrasonic transducer and an array thereof are provided. This electromagnetic ultrasonic transducer includes a support, an elastic board disposed on the support, a magnetizer on the elastic board, and a magnet field generator for vibrating the magnetizer, wherein, the thickness of the magnetizer is of the order of microns. The thickness of the elastic board is also of the order of microns. This electromagnetic ultrasonic transducer is able to produce acoustic waves of high frequency, which are useful for ultrasonic therapy.

Abstract: A magnetic circuit part of a loudspeaker is formed of a plate, a magnet, and a yoke. A step is disposed in the plate that comes into contact with a disc-like magnet and forms a magnetic gap. A loudspeaker is provided where the step moves a voice coil away from the leakage magnetic field of the yoke, the influence of the leakage magnetic field is eliminated even when the output is large, the distortion is small, and the sound quality is high.

Abstract: A drive cone 11 and a diaphragm 14 are integrally driven by a voice coil 6 movably disposed in a magnetic gap 5. Peripheral edge portions of the drive cone 11 and the diaphragm 14 are supported by a frame 12 via different edge portions 13 and 15, respectively. The drive cone 11 is provided with a rising-up portion 11a which rises up toward an acoustic radiation direction from a inner circumferential end, and a rising-down portion 11b which rises down toward a direction reverse to the acoustic radiation direction. An inner circumferential edge of the diaphragm 14 is fixed at an annular top formed between the rising-up portion and the rising-down portion. Moreover, a first rib 11c and a second rib 11d are formed on the drive cone 11 in such a manner as to rise up toward the acoustic radiation direction integrally with the drive cone. The diaphragm 14 is supported also at the tips of the ribs.

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: The present invention relates to a miniature electro-acoustic transducer comprising a voice coil comprising an air gap voice coil portion at least partly positioned in an air gap of a magnet assembly, and a second voice coil portion attached to a diaphragm of the miniature transducer. The thickness of the second voice coil portion is 2-5 times larger than the thickness of the first voice coil portion. Moreover, the present invention relates to a voice coil for use in a miniature electro-acoustic transducer.

Abstract: A speaker includes a magnetic circuit 1 that is formed in the center of a frame 5, a voice coil 6 that is inserted in a magnetic gap of the magnetic circuit 1, a damper 7 that is fixed to the frame 5 and the voice coil 6, and a vibrating plate 8 that is fixed to the frame 5 and the voice coil 6. An opening 10 is provided in a bobbin 12 of the voice coil 6. The area of the opening 10 is 0.3% or less of the radial cross-sectional area of the bobbin 12 of the voice coil 6.

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: An electroacoustic vibrating transducer is disclosed. The electroacoustic vibrating transducer includes a frame defines a hollow space, a yoke positioned in the hollow space, and a elastic member mounted on the frame. The elastic member includes a circular plane lamina and a plurality of elastic arms extending outwardly from the circumference of the circular plane lamina. The yoke includes a bottom wall and a sidewall extending vertically from the bottom wall, and the sidewall defines a plurality of gaps corresponding to the elastic arms. Each of the elastic arms is intermittently received in the gaps during the vibration of the elastic member.

Abstract: A diaphragm has a back plane which has a voice coil attached thereto, and a front plane which is located on the side opposite to the back plane. The diaphragm also includes a center portion, a boundary portion which surrounds the center portion and has the voice coil attached thereto, an outer circumferential portion which surrounds the boundary portion, and an edge which surrounds the outer circumferential portion. A frame has a support portion which supports the back plane of the diaphragm. The outer circumferential portion has a convex shape which protrudes in the thickness direction extending from the front plane to the hack plane with respect to the edge.

Abstract: A loudspeaker includes a frame, a magnetic circuit supported by the frame, voice coil body provided movably in relation to a magnetic gap provided at the magnetic circuit, a diaphragm having an outer rim being joined via a first edge to the frame and an inner rim being joined to the voice coil body, and a damper located towards the magnetic circuit from the diaphragm. The damper has an inner rim joined to the voice coil body. The damper has an outer rim joined via a second edge to the frame. The second edge protrudes towards the diaphragm or in a direction opposite to the diaphragm. The damper includes a first protrusion protruding towards the diaphragm and a second protrusion protruding in a direction opposite to a direction in which the first protrusion protrudes. A protrusion out of the first and second protrusions is closest to the second edge among the protrusions.

Abstract: A loudspeaker is provided in which precise alignment is obtained between the frame and motor assembly before they are connected to one another so that a voice coil coupled to the frame may be properly radially and vertically positioned with respect to a magnetic gap in the motor assembly while allowing the motor assembly and frame to be easily and quickly separated from one another to perform repairs or complete replacement of the motor assembly.

Abstract: A voice coil bobbin, which transmits a motive force from the voice coil wound around the bobbin to a diaphragm, includes a main part, a reinforcement part formed on the surface side of the main part, and a middle part formed between the main part and the reinforcement part and made of a material which has a lower density than the other two parts, preferably a non-woven cloth. Thus, there can be provided with the simple-design, high-rigidity voice coil bobbin with high internal loss and a speaker system capable of high-quality sound reproduction.

Abstract: A magnetic structure generating a magnetic field for an ironless motor of an electrodynamic loudspeaker having a mobile coil, wherein the magnetic structure generates a magnetic field in a gap in which the coil is arranged. The magnetic structure includes of a stack of three magnets corresponding to one intermediate magnet and two top and bottom covering magnets, the magnets forming a straight gap border and being located side by side, the intermediate magnet having a radial magnetic polarization, the covering magnets having identical magnetic polarizations and remanent magnetizations. The covering magnets have a radial or axial magnetic polarization. When magnetic polarization of the covering magnets is radial, remanent magnetization of each covering magnet is higher than remanent magnetization of the intermediate magnet, and when magnetic polarization of the covering magnets is axial, remanent magnetization of each covering magnet is lower than remanent magnetization of the intermediate magnet.

Abstract: It is an object of the present invention to use a simplified structure to improve a strength of a neck portion of a conical diaphragm in the vicinity of a voice coil fixing section, thereby inhibiting an undesired dividing vibration in a speaker device. The speaker device of the present invention comprises: a generally conical diaphragm having an opening formed in a generally central position thereof; a voice coil bobbin fixed in the inner circumferential portion of the foregoing opening of the diaphragm; and a diaphragm reinforcing annular member disposed near a fixing section fixing together the diaphragm and the voice coil bobbin.

Abstract: A diaphragm and a speaker unit which can prevent generation of abnormal sound by suppressing rolling phenomenon. The speaker unit has a diaphragm. The diaphragm includes a portion for supporting a voice coil, and a sound emitting portion formed continuously to one end thereof. The voice coil supporting portion has a shape extending reversely to the sound emitting direction. The sound emitting portion includes a step portion having a surface substantially perpendicular to the sound emitting direction, and a bent portion having a cross-section bent toward the inside of the voice coil supporting portion from one end of the step portion.

Abstract: A voice coil using a surface mount technology (SMT) to connect the voice coil and an electrode to each other, and a SMT speaker using the voice coil. A voice coil assembly includes a voice coil formed by stacking a plurality of laminated metal plates; and a flexible printed circuit board (FPCB) for impedance matching between the voice coil and an electrode terminal for connecting an external device and for connecting the voice coil to the electrode terminal. The laminated metal plates of the voice coil are connected in series or in parallel to each other. An active device is installed on the FPCB so as to amplify a signal input through the electrode terminal and to apply the signal to the voice coil. Since the voice coil is formed by stacking the laminated metal plates and is connected to the electrode terminal through the FPCB, a SMT is used to manufacture the SMT speaker, thereby improving productivity and reliability.

Abstract: The present invention is to provide a device with dynamic magnet speaker, which comprises a first housing member having a wall and a first magnetic element fixed on an inner surface of the wall; a seat having a first side connected to the first housing member to define a first receiving space between the first housing member and the first side of the seat; and a hollow tube fixedly provided on the seat and corresponding in position to the first magnetic element, wherein a first coil unit is fixedly mounted around the hollow tube, and the hollow tube extends toward the first magnetic element and is either mounted around an outer periphery of the first magnetic element or inserted in a first central hole of the first magnetic element, so as to not only reduce the weight and spatial volume thereof, but also substantially lower the directivity of sound produced.

Abstract: A loudspeaker comprises a diaphragm, an edge operable to support, on a frame, the diaphragm in such a manner that enables vibration thereof, and a voice coil operable to generate a driving force. The voice coil is of an approximate rectangular shape, and a length of a long axis direction of the voice coil is no less than 60% of a length of a long axis direction of the diaphragm. Positions of long sides of the voice coil to be fixed on the diaphragm are positions corresponding to nodes of a primary resonance mode in a short axis direction of the diaphragm, or in the respective vicinities thereof. Accordingly, it is possible to realize a high sound quality loudspeaker having a narrow width (elongated structure), but not easily causing resonance, thereby obtaining a flat frequency characteristic.

Abstract: A flat acoustic transducer (100) includes a permanent magnet (10) and a magnetic member (20), which are arranged adjacent to each other with a predetermined interval, a flat vibrating membrane (30), provided facing the permanent magnet (10) and the magnetic member (20), and at least one coil (40), fixed to the vibrating membrane (30). In the flat acoustic transducer (100), an electrical signal is applied to the coil (40), to obtain vibration force (F) on the vibrating membrane (30) by way of a magnetic flux ? generated between a magnetic pole face (12) of the permanent magnet (10) and the magnetic member (20), a step (50) is provided between the magnetic pole face (12) and the upper face (22) of the magnetic member (20), while at least part of a winding (42) of the coil (40) at the time of no application of an electrical signal is arranged inside the step (50).

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 loudspeaker includes a basket defining a center hole therethrough, a conduction wire board fixed to the bottom surface of the basket, a magnet placed on the basket, a diaphragm arranged on the basket and above the magnet, and a voice coil. The conduction wire board defines a core hole corresponding to the center hole, and two welding foils on the bottom surface. The magnet defines a through hole corresponding to the center hole. The voice coil is wrapped around the magnet and fixed to the bottom of the diaphragm. The voice coil has leading wires, which bend inward at the top and downward pass through the through hole of the magnet, the center hole of the basket and the core hole of the conduction wire board, and then extend toward two sides of the rivet for being welded on the corresponding welding foils.

Abstract: A system for compensating and driving a loudspeaker includes an open loop loudspeaker controller that receives and processes an audio input signal and provides an audio output signal. A dynamic model of the loudspeaker receives the audio output signal, and models the behavior of the loudspeaker and provides predictive loudspeaker behavior data indicative thereof. The open loop loudspeaker controller receives the predictive loudspeaker behavior data and the audio input signal, and provides the audio output signal as a function of the audio input signal and the predictive loudspeaker behavior data.

Abstract: An uncured fluid adhesive is charged into a groove surrounding the outer circumference of a voice coil so that the inner circumferential edge of a diaphragm is immersed in the adhesive. The cured adhesive securely bonds the diaphragm to the voice coil, and thus the diaphragm can be driven at high output.

Abstract: An audio loudspeaker having an induction motor whose yoke components are formed of powdered iron or other material which is highly magnetically permeable and highly electrically resistive. The oscillating magnetic flux caused by the alternating current applied to the primary coil induces eddy currents in the shorted turn secondary coil but not in the yoke components. This reduces heating of the yoke components, reduces flux modulation, and reduces wasted power.

Abstract: A speaker unit that can prevent a lead from being broken is provided. The speaker unit includes: a diaphragm; a voice coil which is secured to the diaphragm; and a lead which is connected to the voice coil to energize the voice coil. The diaphragm includes an annular securing portion which has the voice coil secured thereto, and an outer projection which projects with respect to the securing portion at a side corresponding to a surface of the diaphragm having the voice coil secured thereto and extends along the securing portion. The outer projection has a top. The outer projection has the top partially recessed to have a recess. The lead extends across the recess to traverse the outer projection.

Abstract: To provide a thin speaker device capable of emitting a loud reproduced sound with a comparatively simple structure, and to input the audio signal to the voice coil not to have an adverse effect on the vibration of the voice coil is executed. A speaker device includes a vibration direction converter part transmitting the vibration of the voice coil to the diaphragm, and a holding part holding the voice coil at the static part such that the voice coil vibrates linearly, and the audio signal inputted to an audio signal input terminal provided at the static part is inputted to the voice coil via the holding part.

Abstract: A leader line of a voice coil from a conductive wire part is drawn out from a part between a diaphragm coupling part and a part disposed in the magnetic gap toward a frame in a non-contact state with a diaphragm. One end side of the second edge made of an elastic body is coupled to a part between a drawing part of the leader line on the voice coil and a part of the voice coil disposed in the magnetic gap. The other end side of the second edge is coupled to the frame. A suspension holder is integrated with the proximity of a coupling part of the second edge to the voice coil. The suspension holder is stuck to the voice coil using an adhesive. The disturbance of the movement of the voice coil can be reduced.

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: An audio speaker having a removable voice coil, which may be a part of a voice coil assembly. The voice coil may be user-removable to facilitate replacement of a damaged voice coil or reconfiguration of a speaker system. Properly positioning the voice coil assembly may provide a solder-free electrical connection between the voice coil and leads that provide current to the voice coil. In some embodiments, the voice coil is user-removably attached to an inner circumferential surface of a diaphragm. In other embodiments, the voice coil is connected to the diaphragm, and the voice coil assembly and the diaphragm are both user-removably attached to a frame.

Abstract: An apparatus and a method for driving a voice coil actuator of a camera are disclosed. In the apparatus for driving a voice coil actuator of a camera, when an input shaping execution unit generates a shaping signal using a resonance frequency of the voice coil actuator to output a drive control signal subjected to input shaping, a drive circuit unit controls an operation of the voice coil actuator connected to a rear end according to the drive control signal using the shaping signal as an initial input. The shaping signal is used for removing resonance of the voice coil actuator and may be one of a 2-step shaping signal, a multi-step shaping signal having 4 or more steps, a linear shaping signal, a toggle shaping signal and the like. Accordingly, it is possible to control undesirable vibration by reducing high resonance response characteristics of the voice coil actuator and it is possible to implement an autofocus function more precisely.

Abstract: A bobbin interconnection assembly in a moving coil loudspeaker is disclosed. The assembly includes a first coupling member fixed to a central region of a diaphragm of the loudspeaker. The assembly also includes a second coupling member that may be removably engaged to the first coupling member. The second coupling member is fixed to an inner rim of an annular damper, and to a voice coil bobbin.

Abstract: A speaker includes a magnetic circuit defining a magnetic gap, a diaphragm defining a central part and peripheral part surrounded the central part of the diaphragm, a coil defining an end suspended in the magnetic gap, an elastic plate defining a central flat coupled to the central part of the diaphragm and a side coupled to another end of the coil. And the side of the elastic plate comprises a first part extending perpendicularly from the central flat toward the peripheral part of the diaphragm and a second part extending parallel to the central flat for coupling another end of the coil.

Abstract: A speaker unit of the present invention includes a frame made of a synthetic resin, inside which a voice coil is disposed in a space between a pole piece and a yoke. A diaphragm is coupled to the voice coil. A pair of lead wires extending from the voice coil are passed between the yoke and the diaphragm, and led out of the frame. The frame has a receiving surface for receiving collisions of the lead wires due to vibrations of the diaphragm, which is formed outer than an end face of the yoke opposed to the diaphragm, and closer to the diaphragm than the end face.

Abstract: A speaker device includes a voice coil unit and a diaphragm linked to the voice coil unit. A first supporting unit and a second supporting unit elastically support the end portions of the voice coil unit so that the voice coil portion of the voice coil unit can vibrate within the magnetic gap in the direction of the face thereof. Each of the first supporting unit and the second supporting unit has a configuration that is in a shape bent so as to extend up and bend down from an end that is fixed to a fixing position. Thus, a speaker device in which the voice coil unit can vibrate with a greater amplitude is provided.

Abstract: A light weight and low profile speaker apparatus is provided. In one embodiment, the speaker apparatus includes: a frame member; a magnetic circuit; a supporting member disposed on a bottom portion of the frame member for securing and supporting the magnetic circuit at an opposite circumferential end portion of a circumferential wall portion of a first yoke relative to a plate portion; a voice coil unit disposed inside a magnetic gap in the magnetic circuit; a coupling member disposed outward of the circumferential wall portion of the first yoke; and a diaphragm having an inner circumferential end portion coupled to the coupling member. The voice coil unit and the coupling member are joined by a joint member that extends in a direction transverse to the circumferential wall portion of the first yoke; and a space where the joint member joining the voice coil unit and the coupling member can move is formed in each of the circumferential wall portion of the first yoke and the supporting member.

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: The invention relates to a voice coil support (21) for a coil transducer motor structure (10) having a first surface (26) towards one end and a second surface (22) towards the other end along an axis of displacement Z, the voice coil support being adapted to receive at least one coil (22H, 22L) wound therearound an outer surface (27) arranged in use for displacing the voice coil support (21) along its axis of displacement Z, as a current is driven through the coils (22H, 22L) when the voice coil support (21) is placed in a magnetic field, characterized in that the voice coil support (21) comprises a material adapted to prevent airflow communication between at least the first surface (26) and the second surface (22).

Abstract: A cone speaker that outputs audio by transmitting to a truncated cone, the movements of a voice coil driven when an audio current is transmitted through a voice coil placed inside a magnetic circuit formed in a space that surrounds a pole piece. Inside a space between the back surface of a center cap attached to a central portion of the cone and the apical surface of the pole piece that faces the center cap, a first filling material composed of a flexible porous body with a low porosity fills the periphery of the space and a second filling material composed of a flexible porous body with a higher porosity than the first filling material fills the central portion thereof.

Abstract: A speaker may include a center pole and a voice coil bobbin having a bobbin that may include nonmagnetic and electric conductor layers and insulator layers disposed between the electric conductor layers. An electrostatic capacity, which is formed between the center pole and the voice coil bobbin, is detected and outputted as an electrical signal.

Abstract: A flat speaker device capable of emitting loud reproduced sound with a relatively simple configuration is provided. The speaker device includes a diaphragm, a frame supporting the diaphragm vibratably in the vibration direction, a magnetic circuit disposed in the frame, and a driving member for driving the diaphragm. The driving member includes a voice coil movably disposed in a magnetic gap of the magnetic circuit, a driving part formed movably in a direction different from the vibration direction of the diaphragm, and an angle conversion and transmission part, one end of which is angle-variably joined to the driving part and another end of which is angle-variably joined to the diaphragm. The angle conversion and transmission part has rigidity and is obliquely disposed with respect to each of the vibration direction of the diaphragm and the moving direction of the driving part.

Abstract: A magnetic system for an electroacoustic transducer, including an annular magnet which provides a magnetic field for a moving coil. The magnetic system has a first magnetic element forming a base plate and at least one second magnetic element forming a cover plate. The annular magnet is arranged between the first and second magnetic element. The annular magnet is held by the magnetic forces acting between the first magnetic element and the magnet, or between the magnet and the second magnetic element.

Abstract: The present disclosure relates to a voice coil lead wire and a loudspeaker using the same. The voice coil lead wire includes a lead wire structure and a core wire structure. The lead wire structure includes at least one lead wire. The core wire structure includes at least one carbon nanotube wire structure. The carbon nanotube wire structure includes a plurality of carbon nanotubes. The at least one lead wire winds around the at least one carbon nanotube wire structure in a helix manner or a twisted manner.

Abstract: The speaker according to the present invention comprises: a magnetic circuit; a diaphragm, a part of which is located in a magnetic gap formed in the magnetic circuit; a ring-shaped first voice coil formed on a first vibrating surface of the diaphragm; a ring-shaped second voice coil which is formed on a second vibrating surface of the diaphragm, the second vibrating surface being an opposite surface to the first vibrating surface, and which is electrically conducted with the first voice coil; and an edge firmly fixed on an outer margin of the first vibrating surface and operable to support the diaphragm in such a manner that enables vibration. The first voice coil is formed so as to be located inside of an inner circumference of the edge and also within the magnetic gap. The second voice coil is formed so as to have at least a part of an outermost circumference thereof is located outside of the inner circumference of the edge and within the magnetic gap.

Abstract: A speaker may include a voice coil bobbin and a center pole. The voice coil bobbin may include a nonmetallic pipe body as a base of the voice coil bobbin, a first nonmagnetic and electric conductor film which is formed on an inner peripheral face of the pipe body, and a second electric conductor film which is formed on an outer peripheral face of the pipe body such that the first electric conductor film is covered by the second electric conductor film through the pipe body. An electrostatic capacity that is formed between the voice coil bobbin and the center pole is detected and outputted as an electric signal.