Abstract: A loudspeaker device 1 includes an acoustic diaphragm 5 composed of a domed diaphragm 11, an edge-like diaphragm 13, and a junctional flat portion 12 which joins those domed and edge-like diaphragms, and a joined portion 23 where an end surface of a bobbin 4 of a voice coil or of a conductive 1-turn ring 3 is stuck and fixed to the junctional flat portion 12 or a reinforcement ring 15; and the reinforcement ring 15 is stuck and fixed to the junctional flat portion 12 from above or from under, thereby increasing the mechanical strength of the junctional flat portion 12 of the acoustic diaphragm 5. A loudspeaker device in which unnecessary vibrations are removed and also the quality of acoustic signals is excellent up to high range is provided.

Abstract: A speaker apparatus comprises a dome type diaphragm comprising: a reinforcing rib; and an edge damper integrally formed with an outer periphery of the dome type diaphragm; and a frame supporting the dome type diaphragm through the edge damper. The reinforcing rib comprises at least one of a groove portion and a ridge portion. The reinforcing rib is extended radially with respect to the dome center portion from a vicinity of a dome center portion of the dome type diaphragm to a dome outer periphery side.

Abstract: A passive radiator has an arcuate contour that follows the contour of a surface where the passive radiator can be mounted. The component may be for example a television set, audio component, high fidelity loudspeaker, home theatre loudspeaker, or subwoofer. The arcuate contour of the passive radiator may be convex, parabolic, hyperbolic, or a combination thereof. Furthermore, the contour of the surface may be cylindrical, spherical or another contour depending on the surface contour of the enclosure where it is mounted. The passive radiator rim shape may be circular, rounded, rectangular, ovular, elliptical or any other suitable shape. A contoured passive radiator of relatively large size can be mounted on a relatively small TV set to produce a better bass sound.

Abstract: An audio transducer for use in a loudspeaker system. The transducer includes a rigid base, a pair of flexible, curved diaphragms and each diaphragm having a distal end and a proximal end. The curved diaphragms form hemi-cylindrical lobes being substantially tangent to one another at their proximal ends and are attached to energy absorbent dampers at their distal ends. The transducers can be employed in a line array as part of the loudspeaker system as well as some of the transducers facing forward while others rearward and, in doing so, their amplitudes and phases can be adjusted for fine tailoring the geometric coverage of acoustic energy radiating from the loudspeaker system.

Abstract: In a loudspeaker, a lead wire of a voice coil is fastened to a diaphragm, and is extended along the diaphragm. A bottom surface of a frame supporting the diaphragm is placed so as to face against a rear surface of the diaphragm. A protrusion is formed on the bottom surface so as to protrude toward the rear surface of the diaphragm. Therefore, the loudspeaker can prevent the lead wire of the voice coil, which is extending along the diaphragm, from being broken. Further, the loudspeaker can prevent the forward protruding diaphragm from being crushed and damaged.

Abstract: A loudspeaker includes a magnetic circuit having a magnetic gap, a frame coupled to the magnetic circuit, a voice coil having a first end positioned in the magnetic gap and a second end opposite to the first end, and a diaphragm coupled to the second end of the voice coil and the frame. The voice coil has a center axis provided through the first end and the second end. The diaphragm has a first portion in which the center axis of the voice coil is provided. The first portion of the diaphragm is provided inside the voice coil. The diaphragm further has a second portion outside the voice coil. One of the first portion and the second portion of the diaphragm has a cross section in a plane including the center axis, and the cross section of the one of the first portion and the second portion of the diaphragm has an elliptic-arc shape. This loudspeaker has a small thickness, has a high sound pressure level in a high frequency range, and secures a wide reproduction range in high frequencies.

Abstract: The present invention relates to a hi-fi speaker. The diaphragm (1) is comprised of a frame member (2) and filler members (3) filled in the frame member (2). The frame member is comprised of flat plates all of which are arranged in parallel to the vibration direction and radially from the center of the diaphragm (1) toward the outer circumference, are fastened together at the radial center, and are fastened to the drive part (6). This frame member (2) has a high rigidity. The filler members (3) are comprised of foamed material etc. This diaphragm (1) does not have any skins, therefore also does not have any problem with resonance. The sound is emitted from the filler members (3). In the suspension (7), rod-like members (12) are fastened in a line at the both ends of the first leaf spring (11), second leaf springs (13) are fastened to the both ends of the rod-like members perpendicular to the rod-like members, and the both ends of the second leaf springs are fastened to unmovable parts of the speaker.

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.

Abstract: A loudspeaker apparatus in which a diaphragm is reinforced easily and favorably. The loudspeaker apparatus includes a loudspeaker diaphragm formed by joining a domed diaphragm and an edge-like diaphragm and vibrated using a voice coil, and a reinforcement ring reinforcing a junctional flat portion or the vicinity of the junctional flat portion of the diaphragm. The reinforcement ring is formed of a permeable material, and the permeable reinforcement ring is stuck to the junctional flat portion or the vicinity of the junctional flat portion of the diaphragm.

Abstract: A dome-shaped diaphragm includes a dome part which is formed in a dome-like shape and is convex forward in an oscillating direction, a neck part which is provided in continuation to an outer periphery of the dome part, and an edge including a roll part which is formed in a curved shape and is convex forward in the oscillating direction, and continued to the neck part at an inner peripheral edge thereof, wherein the neck part is provided with a curved portion which is convex backward in the oscillating direction, and an outer periphery of the curved portion is smoothly continued to an inner periphery of the roll part.

Abstract: A shallow loudspeaker provided with a chassis (2), a movable body (4), a resilient suspension for guiding the movable body with respect to the chassis along a translation axis (T), and an electric actuator (6) for driving the movable body along the translation axis. The movable body has a diaphragm structure comprising a central domeshaped diaphragm (8) and a cone-shaped diaphragm (10) concentrically arranged with respect to the dome-shaped diaphragm. The cone-shaped diaphragm has a back portion (10b) and a front portion (10f) which is wider than the back portion. Both diaphragms are attached to each other near the back portion of the cone-shaped diaphragm, the cone-shaped diaphragm enveloping the dome-shaped diaphragm.

Abstract: It is an object of the present invention to provide a vibrating plate of a dynamic microphone and a method of manufacturing the vibrating plate. The vibrating plate includes a center dome and a sub-dome which includes a damping thin film having stable quality. Referring to FIG.

Abstract: An edge (29) for supporting a diaphragm assembly (100) with respect to a frame (26) is bonded to the frame (26) along the outer periphery thereof and joined to a diaphragm (27) in a position more peripherally inward than a voice coil (28) along the inner periphery thereof. The edge (29) partly overlaps diaphragm (27). This structure allows downsizing of the speaker, without reducing the sizes of a permanent magnet (21) and the edge (29).

Abstract: There is provided a rigid hinged substrate, which forms a diaphragm for miniature microphones. A series of fingers disposed radially around the perimeter of the diaphragm interacts with mating fingers disposed adjacent the diaphragm with a small gap in between. The fingers are interdigitated. The movement of the diaphragm fingers relative to the fixed fingers varies the capacitance, thereby allowing creation of an electrical signal responsive to varying sound pressure at the diaphragm. Because the fingers may be formed with great stiffness, the classic problem in typical capacitive microphones of attraction of the diaphragm to the back plate is effectively overcome. The multiple fingers allow the creation of a microphone having a high output voltage relative to conventional microphones. This yields a very low noise microphone. The diaphragm may be readily formed using well known silicon microfabrication techniques so as to reduce manufacturing costs.

Abstract: An electro-acoustic transducer comprises a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Abstract: The present invention relates to a plate type speaker adapted to radiate sound by transforming horizontal vibration for vibrating a side of a diaphragm into vertical vibration of the diaphragm. The plate type speaker of the present invention comprises a plate-shaped diaphragm for receiving horizontal vibration to generate vertical vibration; a base frame having a fixing portion to which one end of the diaphragm is coupled; a voice coil plate that has one end connected to the other end of the diaphragm, is mounted on the base frame to horizontally vibrate and has a voice coil wound on either or both of surfaces thereof, and a magnetic body that has opposite polarities at positions spaced apart by predetermined distances from top and bottom surfaces of the voice coil plate and is coupled to the base frame.

Abstract: The present invention relates generally to a compact speaker which includes a diaphragm with an embedded voice coil on the surface of the diaphragm, and a magnet, secured in a frame. Due to the placement and orientation of the voice coil, the improved transducer is compact, easy to manufacture, robust and efficient.

Abstract: A multifunction speaker has a frame made of an insulation material and having a cylindrical portion, a pair of supporting springs secured to the frame and to a magnetic circuit for supporting the magnetic circuit. The magnetic circuit comprises a pole piece having a center pole and a flange on which an annular magnet is mounted. The flange of the pole piece has a pair of positioning projections projected from a periphery of the flange for positioning the magnet.

Abstract: The invention relates to an acoustic transducer generating a sound radiation by compression and expansion of an air mass situated between a mobile membrane and a fixed surface or between two mobile membranes. The present invention concerns a transducer or acoustic loudspeaker of electrodynamic type designed to emit sound waves from a modulated electrical signal. The particular arrangement of the constituent elements of the transducer as presented in the invention enables the generation of an acoustic radiation by compression and expansion of the air mass located between a mobile membrane and a fixed surface or anvil which are distinguished by being placed opposite one another. The direction of the resulting acoustical wave is perpendicular to the direction of displacement of the membrane. This manner of generating an acoustic wave enables the production of transducers with specific electroacoustic directivity characteristics.

Abstract: In an arcuate array of speakers (100) the wind component of air motion near each speaker is converted into sound because the wind is trapped within the arc, and therefore the bass response is improved. The array acts like a single large speaker, of diameter equal to the array diameter, when radiating bass sounds. A central baffle (10) also directs the wind and contributes to converting wind into sound. A semi-circular arc can be used along with a symmetry baffle (500) that further directs the wind, so that the number of speakers required is reduced. The symmetry baffle can be the floor, on which rests a cabinet (1) embodying the arcuate array.

Abstract: A method of manufacturing a speaker using a voice coil insertion jig including providing a voice coil insertion jig, deforming a plurality of moving pieces from a first position elastically toward a central boss side to a second position, inserting the voice coil insertion jig into a voice coil, and restoring the plurality of moving pieces to the first position and holding the voice coil using the plurality of moving pieces. Moreover, the method includes inserting the voice coil insertion jig into a magnetic gap forming a magnetic circuit of the speaker, adhering an inner circumference of a diaphragm of the speaker to the voice coil, adhering an outer circumference of the diaphragm to a frame of the speaker, and deforming the plurality of moving pieces elastically from the first position from toward the center boss side to the second position and extracting the voice coil insertion jig from the magnetic gap.

Abstract: A membrane (20) has a membrane axis (5) and a middle area (50), a central cup-shaped depression (52) being provided around said membrane axis (5), which depression (52) preferably has a connecting channel (53), wherein the middle area (50) comprises groups of stiffening grooves (54, 55, 56, 57) which extend parallel to radial directions and of which a first group of long stiffening grooves (54, 55, 56) extends up to the depression (52), said connecting channel (53) issuing into two of the long stiffening grooves (55, 56), thus interconnecting these two long stiffening grooves (55, 56).

Abstract: The invention relates to a loudspeaker comprising at least one magnet (5), a membrane (2) with an outer edge (32) defining an outer edge plane (30) of the membrane, a bead (3) surrounding the membrane (2), a moving coil (9) which is fixed to the first membrane (2), and a magnet system (4) comprising at least one magnet (9). The loudspeaker also has a supporting structure (1) for receiving the magnet system (4) and the membrane, the membrane being connected to the supporting structure by means of the bead, and the supporting structure has a front side which is oriented towards the membrane and a rear side which is oriented in the opposite direction. The membrane (2) is at least partially convex towards the front, in the predominant acoustic direction (33), and the region (28) of the membrane (2), to which the moving coil is fixed, is arranged in front of the outer edge plane (30) of the membrane.

Abstract: It is an object to provide a vibrating plate of a dynamic microphone and a method of manufacturing the vibrating plate, the vibrating plate having a sub-dome and a center dome to which a voice coil is bonded by an adhesive. A mechanical intensity of the vibrating plate is increased without the vibrating plate formed to a double structure, as well as having an enhanced shock-resistance. According to FIG. 1e, a vibrating plate 1 of a dynamic microphone includes a center dome 10 with an electricity generating voice coil 30 and a sub-dome 20 connecting and communicating with the outer circumference of the center dome 10. The voice coil 30 is bonded to the center dome 10 with a first ultraviolet curing-resin 50 which has relatively high viscosity before hardening and relatively low hardness after hardening. A reinforcing resin layer 60a is integratedly formed in the inner surface of the center dome.

Abstract: A loudspeaker device 1 includes an acoustic diaphragm 5 composed of a domed diaphragm 11, an edge-like diaphragm 13, and a junctional flat portion 12 which joins those domed and edge-like diaphragms, and a joined portion 23 where an end surface of a bobbin 4 of a voice coil or of a conductive 1-turn ring 3 is stuck and fixed to the junctional flat portion 12 or a reinforcement ring 15; and the reinforcement ring 15 is stuck and fixed to the junctional flat portion 12 from above or from under, thereby increasing the mechanical strength of the junctional flat portion 12 of the acoustic diaphragm 5. A loudspeaker device in which unnecessary vibrations are removed and also the quality of acoustic signals is excellent up to high range is provided.

Abstract: A loudspeaker apparatus includes a frame having an opening portion, a magnetic circuit constructed within the opening portion, a voice coil 27 in which a rear opening end portion is inserted into a magnetic gap of the magnetic circuit, a dome type diaphragm covered over the front opening end portion of the voice coil, and an edge for holding an outer peripheral portion of the voice coil freely vibratingly, with the outer peripheral edge attached on an opening portion of the frame. A reinforcing portion formed at an outer peripheral edge of the dome type diaphragm is formed of a flat portion and a cone portion, and has a shape of being folded back in a sound radiating direction toward a front.

Abstract: An electroacoustic transducer of small dimensions has a cup-shaped component made of a metallizable plastic material embedded in a housing component having a housing shape and being of a non-metallizable plastic material. The cup-shaped component has an inner surface provided with a metal coating. A magnet is arranged in the cup-shaped component. A diaphragm is connected to the housing component and has an oscillation coil configured to interact with the magnet.

Abstract: A loudspeaker comprising: a support, a sound-generating element mounted to the support for vibration to generate sound; and an electro-active device coupled between the support and the sound-generating element for vibrating the sound-generating element in response to an electrical signal. The electro-active device comprises a structure extending along a minor axis which extends in a curve around a major axis parallel to the vibration direction of the sound-generating element, the structure comprising successive electro-active portions arranged with electrodes to bend around the minor axis on activation in response to application of the electrical signal to the electrodes, and coupled together such that bending of successive portions causes concomitant rotation of adjacent portions around the minor axis adding incrementally along the minor axis, which rotation causes concomitant change of the axial length of the structure along the major axis.

Abstract: An oval speaker apparatus includes a diaphragm whose outer peripheral shape in a plan view is oval or elliptical; an oval or elliptical voice coil for driving the diaphragm; an edge which is joined to an outer periphery of the diaphragm; and a frame to which an outer peripheral edge of the edge is fixed. Further, lead wire which is led out from the voice coil is wired so as to traverse the surface of the edge along the minor-axis direction of the diaphragm, and is provided with slack.

Abstract: An electro-acoustic transducer for driving a large surface is used to convert electrical signals into sound. The transducer has a housing with a cast aluminum bottom and a molded plastic top. The top and bottom are fastened together by screws with a gasket in between the contacting surfaces to form a housing for a high power electromagnetic voice coil driver mechanism. The top has an opening to allow the voice coil to be centered in its gap by a centering gauge during assembly of the driver. A cap closes the opening once the voice coil is fixed in place in the housing. The op is hexagonal and flat with circular rings in the top surface to allow the top to flex in a controlled manner while supporting the bottom which remains stationary.

Abstract: An edge-driven diaphragm loudspeaker driver is configured such that the suspension system of the driver is connected to the voice coil rather than to the diaphragm. Thus, the diaphragm in the loudspeaker is free of suspension systems connected to or extending from the diaphragm. By attaching the surround suspension to the voice coil rather than to the diaphragm, the diaphragm is isolated from the influence of spurious high frequency vibrations in the suspension system, thereby increasing the performance of the loudspeaker at high frequencies. The loudspeaker driver configuration also provides for a longer excursion range for the voice coil/diaphragm assembly, which allows for the driver components to be more accurately aligned during manufacturing, thereby enabling the loudspeaker driver to operate as a full range unit by producing low output frequencies.

Abstract: It is an object of the invention to provide an improved speaker apparatus which maintains the advantages as an inverted dome speaker and has a good directivity and a thin thickness, as well as a broad playback frequency band extending from a high frequency band to a low frequency band. The speaker apparatus includes a dome diaphragm carrying a voice coil and having a concave cross section protruding towards the voice coil, an edge provided on the outer periphery of the dome diaphragm, having a concave cross section protruding towards the voice coil, and supporting the dome diaphragm on a frame, and a magnetic circuit forming a magnetic gap containing the voice coil. Particularly, the edge has a broad edge width {b=(1.5?3)a} bearing a lower playback frequency band than a playback frequency band born by the dome diaphragm.

Abstract: A speaker is provided that is operable to reproduce ultrahigh frequencies. Specifically, the speaker outputs ultrahigh frequencies up to 100 kHz with stable sound pressure. The speaker may include a disk-shaped piezoelectric ceramic vibrator wherein a piezoelectric ceramic and a metal substrate are bonded; a dome-shaped diaphragm attached to the piezoelectric ceramic vibrator; and a panel that fixes an outer peripheral part of the piezoelectric ceramic vibrator.

Abstract: A microphone for converting sound into an electrical signal includes a generally cylindrical housing including an inlet for receiving sound, an inner backplate, and an outer backplate. The inner and outer backplates are generally cylindrical and substantially concentric with each other. A cylindrical membrane is disposed between the inner and outer backplates. The membrane divides an interior of said housing into a front volume and a back volume. The front volume is in direct communication with the inlet. The backplates and/or membrane are charged. Electronics are included for detecting movement of the membrane relative to the inner and outer backplates in response to the membrane moving when subjected to the sound. The backplates and membrane may be of a shape that approximates a cylinder, such as those that have a hexagonal or octagonal cross-section.

Abstract: A loudspeaker contains a hemispherical vibrator. The end portion of the hemispherical vibrator on the side opposite to the hemispherical curved surface is mounted on the main surface of a first circular baffle board. On the opposite side of the first baffle board from the side where the vibrator is mounted, a second baffle board is arranged so as to be approximately parallel with the first baffle board. The first baffle board and second baffle board are connected by four spacers with a space between them.

Abstract: A speaker apparatus is provided. A frame has a projecting portion projecting toward a diaphragm at the periphery of the frame. The diaphragm has a rising portion extending opposite to the frame from the periphery of the diaphragm and having an outside surface along an inside surface of the frame projecting portion. The outside surface of the rising portion is adhered to the inside surface of the frame projecting portion.

Abstract: A loudspeaker comprising a moving coil and a membrane fastened to a chassis, where the membrane is divided into a concentrically disposed inner membrane part and a concentrically disposed outer membrane part, whereby a meeting area is defined between the inner membrane part and the outer membrane part, the inner membrane part being fastened to an inner moving coil and the outer membrane part being fastened to an outer moving coil.

Abstract: A vented tweeter with a low profile particularly suited for automotive applications where the mounting depth is limited. The tweeter comprises a motor with a central air passage extending through it and a lateral air chamber formed around it. Radial channels on the top of the motor connect the air gap in the motor with the central air passage, and radial channels under the motor connect the central air passage with the lateral air chamber. As the diaphragm oscillates, air can move back and forth between the air gap around the magnet and lateral space outside the motor. This configuration substantially increases the volume of air that can be acted on by the diaphragm without significantly increasing the length of the assembled tweeter or compromising the power of the motor. To enhance the power of the motor, a secondary magnet can be included above the top plate.

Abstract: A piezoelectric speaker includes a piezoelectric vibrator and a metal reflection plate. The piezoelectric vibrator includes a piezoelectric element which has a dome shape with a hollow portion and which is polarized in the thickness direction, a first electrode disposed on the inner surface of the piezoelectric element, a second electrode disposed on the outer surface of the piezoelectric element. The piezoelectric vibrator further includes a hole provided in the top thereof. The reflection plate is arranged to cover the hollow portion of the piezoelectric vibrator.

Abstract: A diaphragm for electroacoustic transducers including loudspeakers as formed substantially in a dome shape having an outer periphery of a circular shape and made excellent in tone quality is provided. The dome shape of the diaphragm has an irregular section with a central arcuate edge line of a radius of curvature across the circular outer periphery and passing through an apex of the dome shape, and side surfaces formed on both sides of the central edge line respectively to have side edge lines intersecting at right angles the central edge line and having a radius of curvature larger than that of the central edge line. The side edge lines of both side surfaces are of constant radius of curvature at least in one of the surfaces or of mutually equal radius of curvature at all positions intersecting the central edge line, to be mutually asymmetric or symmetric for dispersing resonating portions over the whole area of the dome shape.

Abstract: The present invention relates to a process for producing a shaped diaphragm for electroacoustic transducers which comprises a core layer comprising poly(meth)acrylimide foam and at least one covering layer, which is characterized in that

Abstract: A lead wire of a voice coil is wired along the surface of a diaphragm. The lead wire is bent toward a reverse side of the diaphragm at a peripheral edge portion of the diaphragm. The lead wire is led to the interior of a frame. An external terminal is provided to extend from outside to inside the frame. In addition, a connecting portion for connecting the lead wire and the external terminal is provided inside the frame. The connecting portion is prevented from coming into contact with another part and becoming short-circuited.

Abstract: Presenting a new Audio Transducer Profile Design and the placement of its components. The speaker cone placement to the voice coil rim and the suspention design connecting the cone assembly to the magnet and frame bar assembly design.

Abstract: An external magnetic-type speaker apparatus includes a magnetic circuit that is provided with a yoke having a center pole, ring-shaped magnet and plate. The magnetic circuit and the edge of a vibrating plate are attached to a support frame. Ventilation holes are formed in the side surface of the support frame for allowing air inside the apparatus to escape.

Abstract: A speaker capable to playback in wide frequency range by means of reducing peak values of amplitude of resonance frequencies in frequency characteristics is provided by means of differing a radius of curvature R1 of an inner diaphragm 10a and a radius of curvature R2 of an outer diaphragm 10b to differ resonance frequencies of the inner diaphragm 10a and the outer diaphragm 10b. Furthermore, by means of equalizing an area S1 of the inner diaphragm 10a and an area S2 of the outer diaphragm 10b, sound pressure levels of the inner and outer diaphragms 10a, 10b are equalized with each other.

Abstract: The invention provides a continuous layer of polymer that is shaped to act as the suspension, the former, and an attachment to the diaphragm. The coil may be located within the pocket providing insulation to the coil thus preventing electrical short circuiting of the voice coil as the voice coil expands or contracts based on its operating temperature. The invention also provides an inner flange area of a suspension that may act as a spring generating additional acoustic energy from the compression driver. The inner flange area may also be tuned to vibrate at a predetermined high frequency. Thus, in certain applications, where more acoustic energy is desired at high frequency, the inner flange area may be tuned to provide that extra acoustic energy. To further increase the high frequency energy generated by the compression driver, the diaphragm may be coupled to the bottom side of the inner flange area.

Abstract: A high frequency transducer having a dome diaphragm with a configuration of a bisected ellipse to overcome the distortion and breaking point of prior art even domes at frequencies above 30 kHz. The dome diaphragm having an annular skirt extending therefrom in an integral fashion and connecting to a disc shaped plate of the transducer. A voice coil of cylindrical section being directly connected to the skirt at a region of close proximity to said dome. The dome being constructed of a rigid material such as a metal, an alloy, a metalloid such as, but not limited to, titanium, aluminum, and boron, or a combination thereof. The dome being constructed in accordance with a general formula for an ellipse (x2/a2)+(y2/b2)=1, and a>b. Wherein a is half of the distance of major axis and b is half of the distance of a minor axis.

Abstract: It is an object of the invention to provide an improved speaker apparatus which maintains the advantages as an inverted dome speaker and has a good directivity and a thin thickness, as well as a broad playback frequency band extending from a high frequency band to a low frequency band. The speaker apparatus includes a dome diaphragm carrying a voice coil and having a concave cross section protruding towards the voice coil, an edge provided on the outer periphery of the dome diaphragm, having a concave cross section protruding towards the voice coil, and supporting the dome diaphragm on a frame, and a magnetic circuit forming a magnetic gap containing the voice coil. Particularly, the edge has a broad edge width {b=(1.5-3)a} bearing a lower playback frequency band than a playback frequency band born by the dome diaphragm.

Abstract: An electro-acoustic converter, comprising a barrel shaped diaphragm (2) formed about a longitudinal axis (3) and comprising first and second annular opposed ends (4, 5), and a first electrically driven vibration generator (6-11) for inducing a vibrational movement in the first annular end in the direction of the longitudinal axis.

Abstract: A diaphragm is gained by the co-molded of a dome part, a voice coil junction part, a cone part and a peripheral part through the injection mold of thermoplastic resin. The thickness of the central part of the dome is made great so that the resonance amplitude in this part becomes small. In addition, an annular rib is integrally provided to the voice coil junction part so as to increase the junction strength between the diaphragm and the voice coil bobbin. Thus, the electromagnetic driving force of the voice coil can be effectively transmitted to the diaphragm so that a loud speaker with excellent characteristics can be gained.