Abstract: An electro-acoustic transducer includes a generally V-shaped diaphragm comprising a folded sheet of film material. The diaphragm also comprises two upper ends, a lower end, an inner surface, and an outer surface. A frame supports the diaphragm in at least the two upper ends of the diaphragm and a structured conductive layer is arranged on a surface of the diaphragm. Permanent magnets are attached to the frame adjacent to the upper two ends and the lower end of the diaphragm.

Abstract: An electro-acoustic transducer has a membrane comprises a folded or curved sheet of film material. A frame supports the membrane in at least an upper end thereof. A resilient suspension connects the upper ends of the membrane to the frame. A driver system is attached to the frame and the membrane for moving the membrane dependent on an electrical input signal. At least one ferromagnetic element is arranged in the membrane or on one of the surfaces of the membrane at its lower end. At least one magnet provides a magnetic field, the magnet being attached to the frame in a position adjacent the lower end of the membrane. The ferromagnetic element is pulled down by a magnetic force between the element and the magnet establishing a gap therebetween such that tensioning of the membrane is achieved by the magnetic force.

Abstract: A ribbon transducer (101) is disclosed, comprising: a ribbon made of conductive material (2), a damping system (4) arranged at least at one end of the conductive ribbon (2), and two rigid supports (103) where the ends of the ribbon (2) are fixed. The damping system (104) comprises a suspension composed of at least one wire (105), anchoring means (107) to connect said ribbon (2) to said wire (105), and elastic means (150) operatively connected to said wire to generate mechanical stress.

Abstract: An acoustic apparatus has permanent magnets 2 and 3, which have north poles and south poles magnetized alternately in a stripe-like fashion, at the front and back of a diaphragm 1, respectively; and has a conductor circuit 4 wired on the diaphragm 1 along the stripe-like poles of the permanent magnets 2 and 3. This offers an advantage of being able to prevent an echo. The diaphragm 1, permanent magnets 2 and 3, conductor circuit 4, spacer 5, and iron plates 6 and 7 are installed in a baffle 8.

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 composite membrane acoustic transducer structure comprising a magnet assembly is arranged adjacent the composite membrane material. The magnet assembly is arranged to produce a flux field. A first layer of thin, elongate composite membrane material is held under tension. A second conductive layer is attached to the first layer of composite membrane material wherein the first and second layers of membrane material are arranged adjacent, generally parallel and offset from the magnet assembly. The assembly is arranged to produce the flux field through at least part of the first layer and the second layer.

Abstract: A ribbonned microphone assembly, for adjustable sound receiving capabilities, including a transducer having a surrounding flux frame for positioning at least two magnets adjacent a suspended ribbon between the magnets. An array of receiving apertures is arranged in the flux frame. At least one curved return ring positioned in the receiving apertures to create a return path for magnetic flux in the transducer.

Abstract: A planar loudspeaker includes a shell pot, a magnet, a diaphragm, and a face plate. The magnet may be positioned in a cavity in the shell pot. The diaphragm may be coupled with the shell pot to cover an entrance to the cavity. The shell pot may include a conductive path having an inner contact proximate the central axis of the diaphragm, and an outer contact proximate to a perimeter of the diaphragm. The face plate may be coupled with the shell pot so that the diaphragm is positioned between the magnet and the faceplate. The face plate may include an inner terminal and an outer terminal that are aligned to be in direct contact with the respective inner contact and the outer contact of the diaphragm and form an electrical connection there between when the face plate is coupled with the shell pot. The inner and outer terminals may be coupled with a source of electrical signals, such as an audio amplifier.

Abstract: The invention provides a speaker in which a damper is effectively added without impairing the thinness of the speaker, and which, although the speaker is thin and small, exhibits high withstand input and high output power performances. A damper (14) is disposed between the lower end of a voice coil bobbin (12) and a magnet (3) of a magnetic circuit (5), and supports a vibration system (13) in a manner that the system is vibratable with respect to the magnet (3).

Abstract: A micro-electro-mechanical systems (MEMS) device includes a back-plate substrate, having an intended region formed with a plurality of perforating holes. A first structural dielectric layer, disposed on the back-plate substrate, wherein the dielectric layer having an opening above the intended region. An etching stop layer, disposed over the first structural dielectric layer. A second structural dielectric layer, formed over the back-plate substrate. The etching stop layer and the second structural dielectric layer form at least a part of a micro-machine diaphragm, and cover over the opening of the first structural dielectric layer to form a chamber between the micro-machine diaphragm and the back-plate substrate.

Abstract: There is provided a capacitive electro-acoustic transducer comprising an active diaphragm (20) and a first and a second diaphragm carrier (60). The active diaphragm (20) is accommodated between the first and second diaphragm carriers (60). The first and second diaphragm carriers (60) each have a respective flat electrode (30). The diaphragm carrier and the electrode are connected together in such a way that the diaphragm carrier projects beyond the electrode by a predetermined amount.

Abstract: Cells can include variable volumes defined between a flexible structure, such as a polymer layer, and a support surface, with the flexible structure and support surface being attached in a first region that surrounds a second region in which they are unattached. Various adhesion structures can attach the flexible structure and the support surface. When unstretched, the flexible structure can lie in a flat position on the support surface. In response to a stretching force away from the support surface, the flexible structure can move out of the flat position, providing the variable volume. Electrodes, such as on the flexible structure, on the support surface, and over the flexible structure, can have charge levels that couple with each other and with the variable volume. A support structure can include a device layer with signal circuitry that provides a signal path between an electrode and external circuitry. One or more ducts can provide fluid communication with each cell's variable volume.

Abstract: An electro-dynamic loudspeaker includes a frame, a magnet and a diaphragm. The frame includes a body portion defining a magnet mounting surface as well as a plurality of protrusions extending from the magnet mounting surface. The magnet is magnetically attracted to the body portion of the frame. The magnet is restricted from movement along the magnet mounting surface by at least one protrusion. The diaphragm is spaced apart from the magnet and coupled to the frame.

Abstract: A ribbon-type electroacoustic transducer such that the acoustic dispersion in the window roughly parallel to the transducers' diaphragm surface is superior to the dispersion of other similar ribbon-type electroacoustic transducers is described. In addition, methods of improving the symmetry of the magnetic field within the motor of the electroacoustic transducer are described. In addition, methods of employing flexible suspension elements attached to a ribbon-type electroacoustic transducer diaphragm such that a shape is created in the diaphragm by the compliance of the flexible suspension elements roughly approximating a smooth curve similar to the smoothly curved diaphragm as described above is described. Additionally, methods of improving the symmetry of the magnetic field within the motor for this shape of diaphragm are described.

Abstract: A speaker including a frame, a diaphragm fixed to the frame through a first edge, a voice coil, a magnetic circuit, and a suspension holder fixed to the frame through a second edge is disclosed. The first and the second edges are spaced apart, and substantially symmetrical in shape with respect to the space between them. The inner periphery of the suspension holder and the inner periphery of the diaphragm are fixed to a part of the voice coil which is located outside of the magnetic gap of the magnetic circuit. The magnetic circuit has a magnet provided outside of the bottom of the frame. The outer periphery of the magnetic extends at least beyond the center of the second edge. The magnetic gap of the magnetic circuit is disposed inside of the frame, above a bottom surface of the frame.

Abstract: A planar magnetic transducer having enhanced magnetic structures which increases performance over a signal-ended device but mitigates some of the drawback of double ended devices, including a supporting structure, a diaphragm incorporating a coil conductor at least primary magnetic structure, and a secondary magnetic structure can be added, including mitigation of high frequency resonance and attenuation by providing a more open architecture, including spacing the magnets wider apart, configuring the inter-magnet spaces to provide better acoustic performance, using high-energy magnets, which magnets can be shaped to form at least a part of the shaped inter-magnet space.

Abstract: “Ribbon tranducer with improved excursion and dispersion characteristics” A method of employing one or more flexible suspension elements attached to a ribbon-type electroacoustic transducer diaphragm such that a bend created in the diaphragm by the flexible suspension element(s) allows the transducer to display broader acoustic dispersion in the plane orthagonal to the net diaphragm surface is described. Additionally, a type of material employed for the flexible suspension which offers minimal acoustic interference to sound radiated from the diaphragm.

Abstract: A ribbon microphone includes a diaphragm made of an aluminum foil. To provide a corrosion resistance and a favorable electrical connection in the junction between the aluminum foil and backplates for a long time, a gold deposited film is formed on opposite surfaces of the diaphragm. Preferably, a gold deposited film is also formed on the inner surfaces of electrode plates attached to each end of the diaphragm.

Abstract: A composite membrane acoustic transducer structure comprising a magnet assembly is arranged adjacent the composite membrane material. The magnet assembly is arranged to produce a flux field. A first layer of thin, elongate composite membrane material is held under tension. A second conductive layer is attached to the first layer of composite membrane material wherein the first and second layers of membrane material are arranged adjacent, generally parallel and offset from the magnet assembly. The assembly is arranged to produce the flux field through at least part of the first layer and the second layer.

Abstract: Electro-dynamic loudspeakers typically include a diaphragm that is secured to a frame and has a conductor applied to at least one surface of the diaphragm. The conductor is connected to a power amplifier for providing electric current through the linear traces of the conductor that interact with magnetic fields generated by magnets that are mounted to the frame. The interaction between the current passing through the conductor and the magnetic fields cause vibration in the diaphragm that creates the sound that is heard from the electro-dynamic loudspeaker. Different methodologies of forming the conductor are provided for simplifying the manufacturing process and for locating the conductor closer to the magnetic field generated by the magnets.

Abstract: An electro-dynamic loudspeaker includes a frame, a plurality of magnets and a diaphragm. The frame includes a molded plastic body. The magnets may be molded into the frame in a determined configuration. The frame is mechanically coupled to the diaphragm such that the magnets are a determined distance from the diaphragm. The diaphragm may include a conductor applied to a surface of the diaphragm. The diaphragm may be driven by a motive force created when current passes through the conductor within a magnetic field formed by the magnets. The electrical current may be varied to create an acoustical output from the electro-dynamic loudspeaker.

Abstract: A flat acoustic conversion device includes two magnets disposed so that their magnetic poles face upward arid are adjacent to or in contact with one another, and the magnetic pole faces of different polarities arc disposed alternately; a vibrating member disposed on the top surface of the yoke; coil pairs wound in helical form and disposed at front and reverse surfaces of the vibrating membrane; such that magnetic flux traveling in a direction substantially parallel to a surface of the vibrating membrane becomes a maximum, and interlinks with the coil pairs. When current is supplied to the coils, a direction of force which the current receives from a magnetic field is substantially orthogonal to the surface of the vibrating membrane, and force in a direction along the surface of the vibrating membrane becomes extremely low. Thus, noise components can be reduced such that sound quality can be improved.

Abstract: A planar electro-acoustic transducer has an adjustable back cap option that provides a dipole/monopole radiation that has different roll-off characteristics. The planar electro-acoustic transducer includes a diaphragm and a plurality of front and rear magnetic bars. Each magnetic bar has a side facing the diaphragm and disposed adjacent thereto. The thickness of each rear magnetic bar is larger than the thickness of each front magnetic bar. The thickness of each front magnetic bar is less than a quarter-wavelength of a cavity resonance at 10 kilohertz. The planar electro-acoustic transducer also includes a non-magnetic acoustically transparent metallic mesh that is disposed coplanarly with the sides of the front and rear magnetic bars that face the diaphragm.

Abstract: An electro-dynamic loudspeaker is typically provided with a diaphragm mounted to a frame in tension. The diaphragm is provided with a plurality of electrical traces that are disposed within a magnetic field of a plurality of magnets that are mounted to the frame. Electric current applied to the circuit causes electric current to pass through the wiring that interacts with the magnetic field of the magnets to thereby cause vibration of the diaphragm that causes the sound generated by the electro-dynamic loudspeaker. Electrical connector arrangements and methods are provided for connecting the electric circuit of the diaphragm to a power amplifier.

Abstract: A planar-magnetic electro-acoustic transducer including a support structure and a magnetic structure carried by the support structure, the magnetic structure comprising a multiplicity of high-energy magnets configured so as to have shared loop field maxima and local loop field maxima, and a diaphragm carried by the support structure, comprising a plurality of conductors carried by and coupled to the diaphragm, said conductors being disposed in relation to local loop maxima and configured to exploit the energy of local loop maxima, as well as the energy of shared loop maxima in driving the diaphragm to produce an acoustic output; and the magnetic structure can be configured so that it includes magnet rows, and the transverse cross-sectional width of the magnets does not exceed their transverse cross-sectional height, and the distance between adjacent elongated magnet rows is greater than one half the width of either of the magnets of the adjacent magnet rows.

Abstract: An electro-dynamic loudspeaker is provided with dampening arrangements that contribute to improved acoustical properties for the electro-dynamic planar loudspeaker. The dampening arrangements include providing a frame having a curved sidewall surface for reducing standing waves. Another design provides for a ferrofluid being disposed between the diaphragm and magnets of the electro-dynamic loudspeaker in order to dampen the resonance frequency of the device. In addition, a diaphragm of an electro-dynamic loudspeaker is provided with a short turn of conductor disposed along a fringe zone at an edge of the diaphragm in order to electro-dynamically dampen the edge resonance of the film.

Abstract: A loudspeaker module in the form of a ribbon element, where the module can be equipped with a membrane, 50 millimeters in width or narrower, and with any length from 50 millimeters to 2500 millimeters. The magnet system is equipped with so called booster-magnets in order to reduce loss of magnetic flow in the soft iron pole pieces and in order to equalize and in order to even the magnetic flow at the magnet ends. The signal-feed is designed in the form of passive current-feeding, whereby the inductance's negative impact of the frequency response up to the 1/f point is eliminated. Above the 1/f point, the ribbon membrane is compensation fed from a separate circuit consisting of R and C, whose values have been chosen in such a way that the resulting frequency response is flat over the whole operating area.

Abstract: An acoustical speaker and planar magnetic transducer therefore wherein the transducer is provided with at least array of spaced magnets which are oriented having their pole faces at an angle with respect to a plane defining a surface of a sound producing diaphragm on which extends an electrical trace circuit.

Abstract: A loudspeaker comprising at least one magnet 27, a yoke 24 fixed to a bottom surface of the magnet, a flat plate 26 fixed on an upper surface of the magnet, a magnetic circuit 29 having a magnetic gap 28 formed between the plate and the yoke, and a flat diaphragm 23 provided with a coil 21 disposed above the magnetic gap. The magnet has a width greater than that of the plate, and at least a part of the upper surface of the magnet is exposed so that it directly faces the diaphragm. According to the structure of the present invention, a larger volume magnet can be used without increasing the size of the magnetic circuit. Furthermore, as magnetic flux can be concentrated in an upper region of the magnetic gap, the magnetic circuit becomes efficient and compact. Thus a compact and high-efficiency loudspeaker for high frequency sound reproduction can be provided.

Abstract: A first conductor and a second conductor are provided at a diaphragm. The first and second conductors intersect magnetic force lines between north poles and south poles of permanent magnets M which are adjacent to one another. When electricity passes through the conductors, a direction in which a force from the magnetic field acts on the current is substantially orthogonal to a surface of the diaphragm. Therefore, the diaphragm can be oscillated in the direction orthogonal to the diaphragm surface. The conductors have widths of from 1000 ?m to 2000 ?m. Therefore, relative errors in the widths caused by etching can be greatly reduced compared to the prior art, and etching is easier. Moreover, the conductors are arranged in a zigzag pattern. Because the conductors do not have a coil form, a large number of through-holes is not required as in conventional products.

Abstract: The present invention is directed to a diaphragmatic (planar) electroacoustic transducer that forms a complete sound radiating transducer and provides high efficiency and linearity. The diaphragm is easily exchangeable and rectangular in shape, and may be made of very thin polyamide film with a plurality of aluminum conductors formed on one side of the diaphragm. The plurality of conductors form two identical and symmetrical coils such that conductors of each coil are interlaced. The two sections of the coils are disposed in dense air-gaps of the magnet system, which comprises a plurality of high (BHmax) Neodymium magnets. The binary interlaced coils can be utilized in a number of modes, for the purpose of accomplishing a variety of operating modes.

Abstract: A planar magnetic transducer having enhanced magnetic structures which increases performance over a single-ended device but mitigates some of the drawbacks of double ended devices, including a supporting structure, a diaphragm incorporating a coil conductor at least a primary magnetic structure, and a secondary magnetic structure can be added, including mitigation of high frequency resonance and attenuation by providing a more open architecture, including spacing the magnets wider apart, configuring the inter-magnet spaces to provide better acoustic performance, using high-energy magnets, which magnets can be shaped to form at least a part of the shaped inter-magnet space.

Abstract: This invention is a loudspeaker that consists of some vibratory membranes and magnets. Every vibratory membrane is a part of a soft conductive tape and is put in a magnetic field. When the membranes conduct audio current, they vibrate air directly with their surfaces, and produce sound waves. This loudspeaker can be made into various shapes. It has overcome the defect of sound distortion caused by the diaphragm deformations in regular loudspeakers. Its distortion is lower, its transient response is excellent, and its voice quality and acoustic effects are admirable.

Abstract: A plane driving type electroacoustic transducer having a film of diaphragm with a conduction pattern formed thereon and a magnetic circuit, wherein a vibration damping layer is provided on the diaphragm.

Abstract: A loudspeaker system, which has the ability to create a homogeneous sound over large distances, comprising at least one line-source of acoustical radiation, each comprising three or more essentially identical speaker-units arranged adjacent to each other at a center-to-center spacing D1, and at least one elongated high frequency transducer arranged in parallel with said line source(s), said elongated high frequency transducer(s) having an essentially continuous radiating surface along the axis of elongation. Where the crossover frequency FCR and the distance D1, for said line-source(s), is set according to new design criteria, taking into account the frequency response from said speaker units in said line-sources and the optimal performance for a line-source. A method is also included, by which a homogeneous sound over large distances can be accomplished.

Abstract: A panel transducer includes a diaphragm with areas of multiple electrical conductors, two rows of magnetic bars, two metal plates and a clamping frame. The diaphragm is clamped in the clamping frame and is positioned between the two rows of magnetic bars. Each row of magnetic plates is in close proximity to the clamped diaphragm. Each metal plate has holes. The holes correspond to spacing areas between the magnetic bars and acoustically connect the diaphragm to outside media. The magnetic bars are sequentially located on the metal plates with spacing between the magnetic bars. The diaphragm is secured to the clamping frame and has an active surface area under tension spaced inwardly of the clamping frame. There are no side magnetic bars at the ends of each of the row. Absorbing strips are used in place of the absent magnetic bars filling the space between the side magnetic bars and the clamping frame.

Abstract: The described invention refers to a new type of loudspeaker module in the form of a ribbon element, designed in such a way that the module can be optionally equipped with a membrane, 50 millimeters in width or narrower, and with any length from 50 millimeters to 2500 millimeters.

Abstract: A planar ribbon transducer includes a mechanism that provides adjustable back cap options for allowing dipole/monopole radiation with different roll-off characteristics for different applications. The planar ribbon transducer also includes front magnet-bars and rear magnet-bars. The thickness of the rear magnetic bars is larger than the thickness of the front magnet-bars while thickness of front magnet-bars is less than a quarter-wavelength of the cavity resonance at 10 kHz, which is 8.5 mm.

Abstract: A speaker damper includes two layers formed by weaving threads to sandwich conductors therebetween. The conductors are to be connected to and driving a voice coil of the speaker. Adhesive material that is applied between the layers fixes the layers and the conductors together. The composite film is then subject to further processing to form a wavy configuration having a number of concentric troughs and ridges. A central bore is defined in the composite film for receiving and retaining the voice coil. The conductors that are sandwiched between the layers is fully protected and conveniently retained. No sewing is required and thus potential damage caused by sewing is completely eliminated.

Abstract: The invention proposes a contact connection for sound reproduction devices according to the flexural wave principle. Since the drive systems 21 of such installations require high current intensities and such current intensities could only be properly transmitted by massive contact connections which however hinder the flexural wave propagation, the object of the invention is to propose a contact connection which eliminates the problems of the state of the art, and which is also very easy to implement. To that end it is proposed that at least one of the two cover layers 12 and/or the core layer 11 contain conductive areas 17 which are connected to the lines 32 of a sound signal source. It is particularly advantageous if the conductive areas 17 can be manufactured together with the components that are also used to manufacture the core layer 11.

Abstract: An electroacoustic transducer which has at least one stator member with an operating surface and a suspended emitter diaphragm spaced from the operating surface of the stator member to enable the diaphragm to oscillate in response to an applied signal voltage. The diaphragm has increased stiffness in a direction along the diaphragm and within the emitter section to enable the emitter diaphragm to oscillate without applying tension in the direction of stiffness. A clamp member secures the diaphragm to maintain the diaphragm in a fixed position relative to the stator to minimize distortion. The clamp member is positioned to define at least two isolated emitter sections for enhancing the frequency response of the transducer. A method is also provided for generating audio output from an electroacoustic transducer.

Abstract: A diaphragmatic (planar) electrocoustic transducer forms a complete sound radiating transducer, with high efficiency and linearity. An easily exchangeable and rectangular in shape diaphragm, of very thin polyamide film is made with a plurality of aluminum conductors formed on one side of said diaphragm. The diaphragm with the plurality of conductors form two identical and symmetrical coils which are the one, inside the other, in an order, that conductors of each coil are interlaced. The two sections of the coils are disposed in dense air-gaps of the magnet system, which comprises a plurality of high (BHmax) Neodymium magnets. The binary interlaced coils can be utilized in a number of modes, for the purpose of accomplishing a variety of operating modes, such as: 1. A series connection provides a higher sensitivity compared to single coil (2). A parallel connection converts the transducer to a higher power standing devise (3).

Abstract: A flexible ribbon speaker is disclosed. A flexible conductive membrane is placed within an appropriately shaped magnetic field formed by a flexible magnet assembly in such a way that current passing through the membrane interacts with the magnetic field, causing the membrane to vibrate and produce sound. The design of the membrane and of the magnet assembly, along with additional structural elements allows the speaker to be bent. Due to its flexibility, the ribbon speaker of the invention can be located in places that were hitherto inconvenient.

Abstract: A ribbon microphone having magnets positioned adjacent north and south pole pieces. The magnets are of uniform thickness along their lengths, and do not taper. The pole pieces are substantially the same width as the magnets. An offset ribbon is disposed in an air gap between the pole pieces. The offset ribbon is not centered in the air gap, but rather is offset from a center line which bisects the magnets and pole pieces. The offset ribbon is located closer to the front of the microphone than the back of the microphone. The flux area is uniform and corresponds to the area of the air gap between the pole pieces.

Abstract: A damper for loudspeaker is constituted by mounting tubular knitted tinsel cords through an adhesive agent of acrylic emulsions having a tackiness onto one surface of a corrugated damper body. The damper is thereby rendered easily manufacturable and highly flexible enough for restraining any breaking of the tinsel cords and improving the reliability.

Abstract: The described invention refers to a new type of loudspeaker module in the form of a ribbon element, designed in such a way that the module can be optionally equipped with a membrane, 50 millimeters in width or narrower, and with any length from 50 millimeters to 2500 millimeters. In the case were the module shall utilize a more narrow ribbon, elongated field concentrating pole shoes are mounted between the magnets and the ribbon. In that way a higher efficiency is achieved and also the risk of edge reflection is reduced. It is furthermore advantageous if the module's soft iron pole pieces, contrary to established practice are mounted along the sides of the magnets in such a way that the membrane is allowed to radiate freely forwards as well as backwards.

Abstract: Speaker includes a diaphragm, and a linear vibrating device attached to a peripheral portion of the diaphragm. The linear vibrating device includes a conductor line meandering in a wave-like shape along the surface of the diaphragm, and magnets disposed in opposed relation to the conductor line. The magnets are disposed in regions surrounded by adjoining mountain portions and adjoining valley portions of the conductor line. The magnets are arranged in such a manner that every adjoining magnets have their magnetic poles of opposite polarities located close to the conductor line.

Abstract: A speaker apparatus in which the acoustic sound is radiated by flexural oscillations of a diaphragm in the form of a panel having a substantially flat surface. The speaker apparatus includes a panel-shaped diaphragm the outer rim of which can be oscillated substantially freely at least in the direction along the diaphragm thickness and at least one driver unit constituting an oscillation source secured to the diaphragm surface for imparting oscillations to the diaphragm. The diaphragm is set into flexural oscillations by oscillations applied from the driver unit driven on the basis of the playback input signal. By flexurally oscillating the diaphragm to radiate the acoustic sound, optimum frequency response characteristics can be obtained over a wide frequency range from the low to high frequency range. Moreover, the acoustic sound of optimum sound quality may be radiated in a state of minimum sound pressure level fluctuations over a frequency range from the low to high frequency range.

Abstract: An electro-dynamic acoustic transducer has a pleated diaphragm in which an accordion-like alternating movement of the adjacent pleats is perpendicular to the radiation (acoustic) axis of the transducer. Front and rear pole plates cooperate to provide a magnetic field across the active area of the diaphragm. Each pole plate may be a “magnetic throat” constructed from a unitary casting of a ferrous magnetic material (such as an iron silicon alloy) having a number of apertures. In an exemplary embodiment, the open area at the rear of the pole plate may be approximately ⅓ the active area of the diaphragm, thereby providing a compression ratio of 3:1. The apertures are substantially uniformly distributed over the effective area of the diaphragm, to provide uniform acoustical coupling and prevent the occurrence of acoustical resonances and standing waves along the diaphragm's length.

Abstract: A planar magnetic acoustical transducer including a diaphragm with electrical circuit carrying conductors having a width substantially equal to a combined width of a plurality of magnetic fields created by equally spaced opposing rows of permanent magnets carried by opposing frame sections between which the diaphragm is mounted such that substantially the entire active area of the diaphragm is driven to create a smooth frequency response. The electrical circuit includes generally parallel segments which are aligned within the magnetic fields created by the rows of opposing magnets and are spaced at a distance relative to one another generally not less than a distance equal to a width of pole elements which are integrally formed with the frame sections and which pole elements are spaced intermediate each of the rows of magnets so as to be in an opposing relationship with one another on opposite sides of the diaphragm.