Abstract: In a diaphragm 1, at a front surface side surface layer of a base material 10 made of pulps 20 which are mainly composed of cellulose, a mixed layer 11 in which the pulps 20, mica 22, and cellulose nanofibers 21 are mixed is formed.

Abstract: A loudspeaker and method of assembly according to this invention provides for simplified replacement of defective parts that can be accomplished by an unskilled worker without the use of gauges, guides, fixtures or other equipment. A moving assembly, and a combined frame and motor structure, are assembled independently of one another and then connected together, within acceptable tolerances, by a centering tee which is affixed to the moving assembly and may be easily connected to and disconnected from the motor structure.

Abstract: Electro-dynamic transducer (1) including: a main magnetic circuit (2) defining an air gap (15), a moving part (16) comprising a dome shaped diaphragm (17) fixed to a movable coil (18) diving into the air gap (15); a support (20) to which the moving part (16) is suspended; a suspension (26) linking the moving part (16) and the support (20); wherein the support (20) at least partly extends in an inner volume inside the moving part (16), wherein the suspension (26) is fixed, by an outer periphery, to an inner face of the moving part (16), and wherein the suspension (26) is made of an acoustically non emitting material.

Abstract: Disclosed loudspeakers include a frame, a magnetic yolk affixed to the frame, a voicecoil, a spider, a resilient surround, and a cone. The yoke includes a slotted sidewall and a central slug that form an air-gap. The voicecoil is disposed within the gap and includes a former, with top and bottom edges, and at least one winding. The voicecoil moves when receiving alternating electrical potentials. The spider has a flexible portion, has rigid members extending through the yolk slots, and has a channel affixed to the former bottom edge such that the channel is no wider than the former and winding(s). The cone includes an inner portion affixed to the former top edge and an outer portion affixed to the frame through the surround, wherein the inner portion includes rigid members capable of movement within the sidewall slots with movement of the voicecoil. Optionally, the former has apertures therethrough.

Abstract: Disclosed loudspeakers include a frame, a magnetic yolk affixed to the frame, a voicecoil, a spider, a resilient surround, and a cone. The yoke includes a slotted sidewall and a central slug that form an air-gap. The voicecoil is within the gap and includes a former, with top and bottom edges, and at least one winding on the former. The voicecoil moves when receiving alternating electrical potentials. The spider has a flexible outer portion, has an inner portion with rigid members that always extend through the yolk slots, and is affixed to the former bottom edge. The cone includes an inner portion affixed to the former top edge and an outer portion affixed to the frame through the surround, wherein the inner portion includes rigid members capable of movement within the sidewall slots with movement of the voicecoil.

Abstract: A micro-speaker includes a frame, a diaphragm mounted on the frame, a magnetic system received in the frame and defining a magnetic gap, a voice coil driving the diaphragm and suspended in the magnetic gap, and a suspension having a body portion and at least a pair of connecting portion extending from the body portion and mounted on the frame. The body portion of the suspension connects with the voice coil and far away from the diaphragm for cooperating with the diaphragm to fix the coil firmly, thereby ensuring the vibrating of the diaphragm is stable and balanced.

Abstract: Electro-dynamic transducer including a main magnetic circuit defining an air gap, a moving part comprising a dome shaped diaphragm and a movable coil fixed thereto and diving into the air gap; a support to which the moving part is suspended; and a suspension linking the moving part and the support; wherein the suspension is floating with respect of the support, allowing a radial degree of freedom.

Abstract: A speaker used as a household appliance is provided. The speaker has an ultra-slim structure suitable for an ultra-slim TV and is applied to a woofer speaker representing a superior low-pitched sound characteristic. The speaker has the ultra-slim structure and improves the low-pitched sound characteristic and sound pressure by increasing the amplitude. Outer appearances of a damper and a frame are changed to enlarge a diameter of a voice coil in comparison with an outer diameter of the speaker, the damper has a two-step structure such that a longitudinal amplitude of an upper side of the damper is increased to improve the low-pitched sound characteristic in a state in which a lower side of the damper is put on the frame, and a size of a vibration plate is enlarged to improve the low-pitched sound characteristic and sound pressure. A flat plate is used as the vibration plate.

Abstract: A loudspeaker has a short support post joined to the forward plate; upper end of the support post in association with the fixing post is joined to the middle part of the drum paper with the fixing post; the voice coil has the upper end thereof joined to the drum paper; when the voice coil drives the drum paper to vibrate and emit sound, the upper end of the short support post sways and generates a small offset because of the lower end of the support post being retained by the forward plate such that the voice coil moves axially in the magnetic clearance without deviation, and the voice coil is incapable of touching the yoke or the forward plate to produce noise; therefore, quality of sound output from the loudspeaker is enhanced effectively.

Abstract: A new type of sound transducer, with high output capability and compact size employs a motor in combination with a displacement amplification system using curved lamina. The motor may be electrostatic, such as piezoelectric, or electrodynamic, such as magnetostrictive, or balanced armature. Newer forms of driver materials such as PMN-PT and layered PZT or Galfenol or Terfenol-D are examples. The design exhibits high source levels, smooth frequency response and uniform directivity. Although the application described herein relates to a low frequency sound source for underwater use, the design is not restricted to low frequencies or to an underwater sound source. Both sound production and reception may be conducted. Further, diaphragmatic displacement pumps and sensors may be equipped with curved lamina, which experience a change of curvature upon excitation of their edges, and which may generate displacement of their edges due to changes of their curvature.

Abstract: A loudspeaker includes a chassis, a diaphragm, a motor system, a first suspension and a second suspension. The chassis has an inner periphery and an outer periphery. The diaphragm has an inner periphery and an outer periphery. The motor system has a magnet assembly connected to the inner periphery of the chassis, and a voice coil assembly connected to the diaphragm. The first suspension has an inner periphery connected to the outer periphery of the diaphragm, and an outer periphery connected to the outer periphery of the chassis. The second suspension has an inner periphery connected to at least one of the magnet assembly and the inner periphery of the chassis, and an outer periphery connected to the diaphragm between the inner and outer periphery.

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

Abstract: An acoustic transducer including a sound producing cone that is activated by a voice coil cylinder having a pair of spaced electrical windings that are retained in spaced relationship from a surround ferromagnetic ring that is carried by a heat sink and wherein a magnetic subassembly is mounted within the voice coil cylinder. The voice coil cylinder is supported by a pair of spaced suspension members or spiders and by the sound producing cone.

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

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

Abstract: An ultra-thin speaker includes a metal upper casing, and a metal lower casing corresponding to the metal upper casing and capable of covering a vibrating membrane, a support frame, a magnet and a yoke between two corresponding internal surfaces of the metal upper and lower casings and forming a contact surface with the yoke, such that after the yoke conducts heat of a heat source to the metal lower casing, the heat is conducted to the metal upper casing through a connection and a contact of the metal upper and lower casings to increase a heat dissipating area, so as to overcome the heat dissipation problem and minimize the overall thickness of the speaker.

Abstract: A method for producing a rigid magnetic circuit component for an electromagnetically operable valve includes: a) providing a base element made of a magnetic or a magnetizable material, b) complete first heat treatment of the base element, c) a local second heat treatment of the base element so as to form a subregion having a microstructure of martensite and residual austenite in the otherwise martensitic base element, and d) installing the finished processed base element as the magnetic circuit component in a magnetic circuit.

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 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 damper including: an outer damper; and an inner damper; wherein the outer damper and the inner damper configured to damp a vibrating portion relative to a fixed portion of a loudspeaker, wherein the outer damper supports the outer periphery of a voice coil of the vibrating portion, and supports the outer periphery of the voice coil relative to the fixed portion, wherein the inner damper supports the inner periphery of the voice coil, and supports the inner periphery of the voice coil relative to the fixed portion.

Abstract: A magnetic circuit is made by magnetically attracting a permanent magnet segment of a partially circular arc in cross section to an outer peripheral surface of a center rod, causing the magnet segment in a magnetically attracted state to face a yoke member, using a nonmagnetic supporter to regulate the magnet segment in position, extracting the center rod from the magnet segment in a position-regulated state, and magnetically attracting and fixing the magnet segment to the yoke member.

Abstract: A loudspeaker drive unit includes at least one voice coil, a diaphragm, permanent magnet element and pole piece element. The permanent magnet element and pole piece element form a magnetic circuit with a pole gap arranged to receive and interact with the voice coil. The magnetic circuit is arranged to provide a magnetic field directed radially in the pole gap. The voice coil, the diaphragm and a support structure forms a voice coil and diaphragm assembly, which is arranged to be a self-supported unit. The voice coil and diaphragm assembly is removable from the magnetic circuit as a separate unit, allowing convenient replacement of the dynamic parts of the loudspeaker drive unit.

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.

Abstract: A motor driven acoustic oscillator or speaker that generates a single frequency acoustic sound. The motor driven acoustic oscillator may be used to emit low frequency (LF) sound waves that generates thrust on an object. The oscillator may be further configured to convert heat energy from a surrounding fluid medium into additional useful mechanical work.

Abstract: A magnetic circuit includes a cylindrical yoke member having an inner circumferential surface and a collar formed at one end thereof and turned back substantially at right angles, and a plurality of permanent magnet segments of a partially circular arc in cross section having respective outer surfaces attracted magnetically to the inner circumferential surface of the cylindrical yoke member and respective one end faces attracted magnetically to the collar of the cylindrical yoke member. The magnetic circuit is manufactured by a method including the steps of magnetically attracting the permanent magnet segments to an outer peripheral surface of a center rod, causing the magnet segments in a magnetically attracted state to face the yoke member, using a nonmagnetic supporter to regulate the magnet segments in position, extracting the center rod from the magnet segments in a position-regulated state, and magnetically attracting and fixing the magnet segments to the yoke member.

Abstract: A microphone sensing element and a method for making the same are disclosed. The sensing element has a diaphragm and an attached electrical lead-out arm preferably made of polysilicon that are separated by an air gap from an underlying backplate region created on a conductive silicon substrate. The backplate region has acoustic holes created by removing an oxide filling in a continuous trench that surrounds hole edges and by removing oxide to form the air gap. The diaphragm is softly constrained along its edge by an elastic element that connects to a surrounding rigid polysilicon layer. The elastic element is typically a polymer such as parylene having a Young's modulus substantially less than that of the diaphragm. First and second electrodes are connected to the diaphragm through the lead-out arm and to the substrate through polysilicon via fillings, respectively, and thereby establish a variable capacitor circuit for acoustic sensing.

Abstract: A speaker according to the present invention is equipped with a diaphragm having a central portion of a dome shape and an edge portion formed on an outer periphery thereof. Further, the speaker has also a frame attached with an outermost fringe of the edge portion and a damper member provided inside the central portion to support the central portion. The damper member supports an inner side surface of a voice coil bobbin also, so that a voice coil can be adequately positioned within a magnetic gap.

Abstract: An electro-acoustic transducer includes a tone generator, a vibrator, and a case. The tone generator includes a diaphragm, and a voice coil joined to the diaphragm. The vibrator includes a magnetic circuit having a magnetic gap at which the voice coil is positioned, and a suspension made of metal and having a first end joined to the magnetic circuit to suspend the magnetic circuit for allowing the magnetic circuit to vibrate. The case is joined to a periphery of the diaphragm, and includes a metal plate joined to a second end of the suspension. The metal plate is joined to the suspensions reliably, hence allowing the electro-acoustic transducer to be manufactured stably.

Abstract: A signal isolation system includes an aeroisolator to couple output signals to an electronic device. The aeroisolator is made from two commercial miniature earphones, each having a ferro-magnetic diaphragm activated by a voice coil in proximity to a permanent magnet. The diaphragm is removed from one of the earphones, and the two earphones are then disposed in proximity to each other, with the diaphragm in proximity to the voice coil of each.

Abstract: A symmetrically loaded, shallow suspension speaker with stiff diaphragm having a minimum dimension that is greater than the diameter of the magnet that drives the diaphragm thus allowing the suspension of the diaphragm to extend nearly to the bottom of the speaker basket on the maximum inward excursion of the voice coil and diaphragm such that the suspension operational depth is not the limiting factor of the overall height of the speaker. The elements of the suspension system are designed to maximize the spacing between the inner and outer portions of the suspension, thus minimizing the possibility of wobble in the speaker. The speaker design maximizes air movement in a given mounting depth with a configuration that optimizes the operation of the moving parts that complements the fixed mechanical structural configuration of the non-moving parts in either an overhung or underhung configuration. The design also accommodates user replacement of the voice coil or cone.

Abstract: A linearly compliant, flexible, resilient and flat speaker damper connected between the frame and the cone of the speaker with electrically conductive paths applied to the damper to conduct the signal to be applied to the voice coil of the speaker. A method for linearly compliant audio speaker damping and a method for application of voice coil conductors on the damper.

Abstract: A loudspeaker includes: a bottom plate; a center pole provided upwardly from the bottom plate; a yoke surrounding the center pole and having a plurality of slits; a magnet for providing a magnetic flux for the center pole and the yoke; a coil provided between the center pole and the yoke; a first annular member for supporting the coil; a plurality of support members for supporting the first annular member, the plurality of support members being inserted into the plurality of slits; and a diaphragm supported by the plurality of support members, wherein upper faces of the plurality of support members gradually decrease in height in a direction away from the first annular member, and wherein a lower face of the coil is located below a position at which the diaphragm is supported by the plurality of support members.

Abstract: In a loudspeaker, even if an interval between a diaphragm and a yoke is small, a lead wire, an end of the coil wire of a voice coil, moves upward and downward in and/or over a cutout portion formed in the yoke, and does not collide with the yoke. The loudspeaker does not have disadvantages, such as noises and disconnection of the end of the coil wire, and can be thin.

Abstract: A speaker having a generally linear response by configuring two elastic members opposite one another so that any non-linearlity in the spring constant between an outward displacement versus an inward displacement are substantially cancelled. The present invention provides a pseudo linear spring constant throughout the range of travel of the cone and voice coil, or the sound baffle for a passive radiator. This minimizes the flexing of the cone and the wobble of the voice coil tube, or the baffle, as each travels to reproduce the audio waves.

Abstract: The speaker disclosed in this invention comprises: (a) a central cap fixed on voice coil bobbin; (b) a shaft fixed in the center of the central cap; and (c) a bearing filled with lubricating fluid and fixed in a through-hole disposed in the center of a magnetic circuit. The speaker has excellent characteristics without sliding noise or harmful rolling phenomena but with reduced harmonic distortion due to the introduction of a magnetic fluid or a lubricant used as a lubricating fluid.

Abstract: A loudspeaker is provided, which includes a frame, a voice coil bobbin, and a diaphragm connected to the frame and the voice coil bobbin, wherein the diaphragm is connected to the voice coil bobbin in such a manner that a cone angle between the diaphragm and the voice coil bobbin becomes small enough to obtain a preferable treble reproduction threshold frequency, the diaphragm ha a first connected portion connected to the voice coil bobbin and a second connected portion connected to the frame, and the diaphragm has an arch-shaped cross section so as to have a top portion formed outward from both the first connected portion and the second connected portion.

Abstract: An open-type magnetic circuitry of loudspeaker includes a lower yoke having a central portion upward projected to form a bobbin, a magnet positioned on top of the bobbin, a voice coil wound around the bobbin and the magnet, and a diaphragm connected at a root portion to the voice coil. The magnetic circuitry of loudspeaker is characterized in that the lower yoke is provided at an upper side surrounding the bobbin with a plurality of radially equally spaced supporting posts, a top end of which being higher than at least a bottom side of the magnet, and that a ring-shaped upper yoke having a central hole is covered onto the top end of the supporting posts, such that heat produced by the voice coil during working could quickly dissipate via the spaces among the supporting posts. Since no heat would accumulate in the loudspeaker, the loudspeaker could always maintain good sound quality.

Abstract: The present invention is a spring suspension speaker that will virtually eliminate failure of the speaker due to fatigue from cyclic stress from regular use of the speaker or due to a surge of power to the speaker. The present invention comprises of a flexible support member installed within the conventional speaker. The present invention improves the performance and the life expectancy of the conventional speaker and also improves the responsiveness of the speaker, thereby increase the accuracy of the sound reproduced by the speaker.

Abstract: A loudspeaker comprising a bobbin, a coil wound around an outer surface of the bobbin, a magnetic circuit having a magnetic gap the coil is inserted, a first cylinder fixed to the outer surface of the bobbin, a second cylinder connected with the first cylinder, a diaphragm and a damper coupled to the outer circumferential surface of the second cylinder, an edge coupled to the diaphragm, a frame on which an outer circumference of the damper and an outer circumference of the edge are fixed, and terminals fixed on the frame and electrically connected with the coil. In a speaker of the present invention, the outer circumference of a yoke constituting the magnetic circuit has a plurality of slits, while the first cylinder and the second cylinder are connected together by a plurality of radially-disposed joints. Speakers in the present invention have a flat profile yet they are compatible with large amplitude and high output power, capable of reproducing a wide range of sounds from a low tone to a high tone.

Abstract: Method for manufacturing speaker bottom yoke, including steps of: 1. calculating product weight according to required dimension; 2. cutting off a blank material with the calculated weight from steel bar (material bar), which blank material can be further planed; 3. performing first time forging to forge one end of the blank material into a stem section with reduced diameter, which stem section can be formed with a sink in accordance with the required shape of the bottom yoke; 4. performing second time forging to forge the other end of the blank material into a bottom disc with larger diameter; and 5. performing third time forging to further forge the bottom disc of the blank material into a predetermined dimension. In the above forging procedure, the diameter of the blank material is forged from large dimension into small dimension and the bottom disc is forged at two times into a specific dimension.

Abstract: The present invention comprises an improved center pole having a distortion reduction cap and an improved method of coupling the cap to a speaker center pole. The speaker assembly comprises a distortion reduction cap and a cylindrical center pole having a gripping surface formed on an outer cylindrical surface of the center pole and a frustoconical recess on a top surface of the center pole. The cap is coupled to the center pole through the application of pressure on the cap to conform the cap to the center pole and to non-rotatably couple the cap onto the center pole by deforming a portion of the cap against the gripping surface. The distortion reduction cap is coupled to the center pole in a manner forming a corresponding frustoconical portion mating with the frustoconical recess on the top surface of the center pole in a manner providing an air tight seal.

Abstract: A speaker apparatus includes a frame having a magnetic circuit, a voice coil bobbin installed in the frame to be magnetically coupled to the magnetic circuit, and a diaphragm movably installed in the frame and fixed to the voice coil bobbin so as to be driven by activating the magnetic circuit. The diaphragm has a positioning portion that had been used for securing the diaphragm relative to the magnetic circuit during an installation of the diaphragm in the frame.

Abstract: The present invention consists of an improved distortion reduction cap and center pole speaker assembly and an improved method of coupling the cap to a speaker center pole. The cap includes an axial flare which is stretched over and pressed into a corresponding axial gripping surface to provide a permanent coupling of the cap to a speaker center pole that does not vibrate or come loose and that eliminates air gaps between the cap and the center pole. The method of coupling the cap to the speaker center pole consists of forming the caps through known die cut stamping and forming a slightly raised corresponding axial gripping surface on the center pole of a speaker pole yoke assembly. The cap is placed over the center pole and then forced into a molding applicator tool.

Abstract: The present invention comprises an improved center pole having a distortion reduction cap and an improved method of coupling the cap to a speaker center pole. The speaker assembly comprises a distortion reduction cap and a cylindrical center pole having a gripping surface formed on an outer cylindrical surface of the center pole and a frustoconical recess on a top surface of the center pole. The cap is coupled to the center pole through the application of pressure on the cap to conform the cap to the center pole and to non-rotatably couple the cap onto the center pole by deforming a portion of the cap against the gripping surface. The distortion reduction cap is coupled to the center pole in a manner forming a corresponding fiustoconical portion mating with the frustoconical recess on the top surface of the center pole in a manner providing an air tight seal.

Abstract: A flat loudspeaker of superior quality for use in audio appliances, in which loudspeaker the generation of abnormal sounds is eliminated by placing a voice coil with a high accuracy in the magnetic gap. A diaphragm is split into a main diaphragm (11) and a sub-diaphragm (12); a voice coil (8) is connected to the inner circumference of the main diaphragm (11) whose inner diameter is substantially identical with the diameter of the magnetic gap (5). In the loudspeaker, the voice coil (8) is placed in a right positioning without inclination and eccentricity relative to the magnetic gap (5), abnormal sounds are eliminated, and a thinner configuration and a lower rejection rate are made compatible.

Abstract: An electromagnetic induction type acoustic transducer apparatus including a magnetic gap formed between a plate and a pole piece serving as assemblies of a magnetic circuit, a conductive ring attached to a diaphragm, the diaphragm interposed within the magnetic gap for generating sounds when it is vibrated, and a flat coil disposed in the plate or the pole piece at the position opposing the magnetic gap and of which winding is increased from the vibration direction of the diaphragm to the direction perpendicular to the vibration direction of the diaphragm, wherein a width of the magnetic gap can be reduced.