Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/06—Loudspeakers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
  • H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/06—Loudspeakers
  • H04R9/066—Loudspeakers using the principle of inertia

Definitions

• the present invention relates generally to inertial type voice coil actuators capable of converting energy between electrical and mechanical form and, more particularly, to an inertial type voice coil actuator that utilizes radially polarized biasing magnets and a multicomponent suspension for alignment of the moving coil.
• Inertial voice coil actuators have been used in the past to acoustically stimulate semirigid structures to radiate sound.
• voice coil actuators have been attached to structures that are relatively large to act as a soundboard such as a wall in a room, where the wall of the room, when acoustically driven radiates sound.
• the length of the coil wire that is within the annular magnetic gap is defined as the length, L. This force is what creates the movement of the coil and subsequently generates sound.
• voice coil transducers are built upon magnetic circuit designs that have classically been used for conventional cone type loudspeakers and not optimized for driving soundboard type structures.
• voice coil actuators often require the use of an external housing to support the heavy magnet assembly relative to the voice coil.
• the voice coil is in communication with the external housing at a location coincident with an acoustic output system that permits the transducer housing to be mechanically attached to a soundboard.
• Loudspeaker motors such as used in the past comprise a magnet circuit assembly including a permanent annular magnet, polarized in the axial direction, and sandwiched between two magnetizable plates.
• One of the plates carries a cylindrical post that extends through a central space defined by the annular magnet, generally referred to as a cylindrical pole piece.
• the other plate has an annular opening, somewhat larger than the diameter of the pole piece, such that an annular magnetic gap is formed between the post and the inner edge of the associated annular plate. The height of the gap is formed by the thickness of the annular plate having the annular opening.
• Voice coil actuators have a moveable voice coil disposed within the annular magnetic gap.
• the coil has a suspension system that typically utilizes an external housing to which the annular magnet and magnetizable plates are also attached.
• the external housing provides radial stiffness and axial compliance to the coil.
• the moving coil has a first end fixedly secured to a radially central portion of the inner surface of the external housing wall.
• a mounting screw secured to an exterior well portion of the exterior housing may be attached to the wall.
• the annular magnet, magnetizable plates, external housing and structural attachment point comprise a system that is large and heavy relative to the total dynamic force the actuator is capable of generating. If the external housing is mounted on a vertical facing surface e.g. a wall, large bending moments are placed on the structural attachment point and the housing must accommodate these moments without translating them to the coil.
• a third objective of the invention is to minimize sound distortion by providing a multi component voice coil suspension system.
• a fourth objective of the invention is to provide an inertial voice coil actuator equipped with a simple mounting system for transducing sound to a soundboard.
• a fifth objective is to provide an inertial voice coil actuator equipped with means to quickly and removably affix the voice coil actuator to various surfaces without the use of adhesive bonding between the output disk and the soundboard and without the need for tools thereby minimizing assembly and repair time.
• Yet another object is to provide a method of enhancing the system for extended high frequency response.
• the novel voice coil actuator includes a magnetic flux conductive material core, a magnet, and an electrical current conductive coil uniquely arranged.
• the core has a first surface and a continuous channel disposed in said first surface.
• the channel has a pair of opposing walls.
• the magnet is radially polarized and disposed in intimate contact with either one of the channel walls and spaced from the opposing channel wall so that a gap remains between the magnet and the opposing wall.
• the magnet has two faces of opposite magnetic polarities; one faces the gap.
• the magnet is further spaced from the bottom of the channel so that magnetic flux is substantially normal from the face across said gap to the wall.
• the electrical current conductive coil is disposed around a coil former and moveably positioned in the gap such that an electrical current in the coil develops a magnetic force on the coil in a direction substantially normal to the magnetic flux to displace the coil in response to the magnetic force.
• a feature of the present invention is the unique arrangement of the components.
• One pole or face of the magnet is adjacent the gap. This construction ensures that the magnetic flux will be uniformly distributed substantially along the length of the gap since the flux emanating from the face is inherently substantially uniform.
• the spacing of the magnet from the bottom of the channel also ensures that leakage flux is minimized since the flux will follow the path of least resistance and will prefer to be confined through the core and gap. The minimizing of leakage obviates the need for bulky shielding which allows for simpler, lighter and smaller packaging than existing actuators.
• a second feature according to the present invention is a multi-component suspension system that supports the electrical current conductive coil in such a manner that the coil has high radial stiffness along with appropriate axial compliance.
• the electrical current conductive coil is wound on the coil former that is typically formed of polymeric material to form a cylindrical shaped object.
• the coil former has a first portion that is external to the magnetic gap and suspended by a disk shaped member known as a spider suspension that provides radial stiffness while providing a restoring force to an axial displacement.
• the spider suspension of the first embodiment includes a concentric corrugation that provides additional compliance in the axial direction.
• a second embodiment includes a second spider suspension spaced vertically from the first, having the same general configuration as the first suspension.
• the spider suspension has an annular opening that is sized to the outer diameter of the voice coil former.
• the spider has an outer diameter that is mechanically associated with a surface of the core.
• the spider suspension system in a preferred embodiment is formed of an elastic or visco -elastic material such as polyurethane, polypropylene, or other polymeric material. More than one spider may be used for added suspension control.
• a second portion of the coil former is internal to the gap and, in one embodiment, a viscous magnetic fluid suspension and an antifriction bearing suspend the second portion.
• the viscous magnetic fluid suspension is a fluid that fills any space between the inner and outer surfaces of the voice coil former, the coil, the face of the magnet, and the wall of the channel.
• the suspension system may also comprise an antifriction bearing surface disposed in intimate contact with one wall of the channel to support the surface of voice coil former.
• the antifriction bearing is sized to provide sufficient clearance for the voice coil former, but in the event of a large radial force, it prevents the voice coil from striking or rubbing the wall of the channel or the face of the magnet. This bearing also provides a spring of infinite compliance along the axial length of the electrical current conductive coil.
• the magnetic fluid is a low viscosity oil, having microscopic ferrous particles such as magnetite, homogeneously suspended in the fluid.
• the oil-magnetic emulsion is attracted to and held in the magnetic field within the magnetic gap by reason of the magnetic flux across this gap.
• the viscous magnetic fluid provides a heat dissipating mechanism and a radial restoring force when the voice coil is radially displaced.
• the antifriction bearing acts as a bearing for the voice coil former.
• a third feature of the present invention includes a unique integrated mounting apparatus providing both quick installation and quick removal features.
• the mounting apparatus transduces vibrations through the coil to the soundboard through an output disk.
• the integrating mounting apparatus comprises the output disk acoustically associated with the soundboard and the coil former.
• Another preferred embodiment includes an integrating mounting apparatus comprising the output disk and a receiver designed to interlock one with the other in such a way as to accurately translate the vibrations without attenuation or distortion to a sound body.
• an interlocking mechanism which comprises at least one wedge-like element on the output disk and at least one complementary engagement opening on the receiver.
• the wedge-like elements on the output disk are positioned to be in communication with a base formed in the receiver thereby providing accurate transmission of vibrations.
• the output disk further registers into the receiver rotationally via pins, tabs or other registration means which assist in placement of the engagement wedge on the wall of the receiver. The output disk can then be rotated and pressured into the receiver.
• a locking means for holding the outplit disk against counter-rotation and in its downward pressured position against the receiver in order to accurately transmit vibrations and forces created by the voice coil actuator to the receiver, and then through the receiver to the substrate or soundboard.
• the distal surface of the output disk can be molded with a very slight convexity.
• the output disk would compress downward, flattening the convexity of the outer surface rendering it flat and causing even forces to propagate throughout the surface.
• Adhesive or conventional fixative means may be used to acoustically couple the receiver and the soundboard. No adhesives between the output disk and receiver are necessary. This mounting arrangement is particularly useful when the voice coil actuator is to remain exposed and minimizes the need for tools and time for assembly, installation, and repair.
• a high frequency speaker element may be mounted in near proximity to the inertial voice coil actuator assembly.
• These high frequency speaker elements can be comprised of any electro- dynamic, piezo-electric, or magnetostrictive type systems.
• the integrated mounting apparatus includes the output disk which comprises an annular opening.
• a high frequency speaker element is co-axially located with the output disk of the voice coil actuator opposite the voice coil actuator assembly and mounted in such a manner that the acoustic output of the high frequency speaker element is directed away from the side on which the inertial type voice coil actuator is mounted.
• the output disk may be mechanically or adhesively affixed to the soundboard.
• the high frequency speaker element is electrically connected with the inertial type voice coil actuator so that the high frequency components of the audio signal are preferentially sent to the high frequency speaker while limiting the low frequency components to the inertial type voice coil actuator.
• Another embodiment of the inertial type voice coil actuator with extended high frequency speaker system uses a plurality of high frequency speaker elements configured in a spatial array.
• the spatial array can be configured in any single, two or three-dimensional geometry.
• the present invention provides a voice coil actuator with superior suspension system and novel construction, which results in a lighter and smaller package, more accurate sound reproduction, and faster, simpler installation for use with large or small soundboards.
• Fig. 1 is a perspective view of the present invention as installed on a large sound body.
• Fig 2. is a fragmentary cross-sectional perspective view along line 2-2 on Fig 1 of the Inertial Type Voice Coil Actuator of the present invention showing its suspension system and construction;
• Fig. 3 is a cross sectional view along line 3-3 of Fig. 1 of the Inertial Type Voice Coil Actuator of the present invention including an acoustic mechanical interface between the output disk and receiver of the present invention;
• Fig. 4 is an exploded perspective view of the present invention showing the integrated mounting apparatus
• Fig. 5 is a top view of the locking portions of the receiver and output disk elements of the integrated mounting apparatus
• Fig. 4a is an exploded perspective view of another embodiment of the integrated mounting apparatus
• Fig. 5a is a top view of the locking portions of the receiver and output disk elements of the second embodiment of the integrated mounting apparatus
• Fig. 6 is a cut away perspective view of the receiver and output disk interlocked, particularly showing the interlocking elements of the integrated mounting apparatus;
• Fig. 6a is a cross section of the output disk along line 6-6 showing a convex surface;
• Fig. 7 is a cross sectional view of a third embodiment of the present invention wherein an additional element in the suspension system is shown;
• Fig. 8 is a cross sectional view of an inertial type voice coil actuator of an embodiment showing a high frequency speaker element co-axially mounted within the output disk; and Fig. 9 is a cross sectional view of the fourth embodiment of the present invention showing a multi element, hemispherical, high frequency array.
• a voice coil actuator assembly 90 includes a core 101, a magnet 105, an electrical current conductive coil 106, and a multi-component suspension system 92 comprising a coil former 107, an antifriction bearing 104, a spider suspension 111, and a spacer 110.
• the core 101 is constructed from magnetic flux conductive material and has a first surface 102 and a continuous channel 103 disposed in the first surface 102 which leaves a center column 120 with a top surface 122.
• the channel has a first wall 108, a second opposing wall 109, a bottom wall 116 and an anti- fringing groove 121.
• An integrated mounting apparatus 94 of a preferred embodiment of the voice coil actuator comprises an output disk 112 (see Figs. 1,2 and 3).
• the integrated mounting apparatus of another embodiment includes an output disk 247 and a receiver 114 with means for interlocking 149 said output disk and said receiver (see Figs. 4-6a).
• a final embodiment includes an output disk 112 having an annular hole 310 as the integrated mounting apparatus (see Figs. 8 and 9).
• the magnet 105 is disposed in intimate contact with the second wall 109 so that a magnetic gap 124 is formed between the magnet and the first wall 108.
• the magnet 105 is cylindrical in shape, is of radial polarization, and comprises a first face 126 of a first magnetic polarity and a second face 128 of a second polarity.
• the first face 126 is adjacent the second wall 109 and the second face 128 is disposed within the gap 124.
• the magnet 105 has a lower edge 115 spaced from the bottom wall 116 of the channel 103 forming an anti-fringing groove 125 and an upper edge 117 coextensive with the top surface 122 of the center column 120.
• magnet 105 may be disposed on either first wall 108 or second wall 109.
• a higher performance design of the present invention will have the magnet 105 disposed on the outer first wall 108 of the channel 103. This alternative arrangement creates a stronger magnetic flux across the gap, thus improving its force output for a given current.
• the coil 106 is moveably suspended in said gap 124 such that an electrical current in the coil 106 develops a magnetic force on the coil 106 in a direction substantially normal to the radial magnetic flux caused by magnet 105 to displace the coil 106 in response to such magnetic force.
• the force will be axial and linearly proportional to the current, as is well known.
• the coil 106 is wound on the coil former 107 that is used to mechanically couple the electro-magnetic force between the magnetic flux from the permanent magnet to the output disk 112.
• the suspension of the coil former 107 in the present invention is designed to maintain radial alignment of the coil 106 within the gap 124 without causing sound distortion.
• This suspension system 92 prevents the coil 106 from striking or rubbing against the wall 108 of the channel 103 or the second face 128 of the magnet while still allowing axial compliance.
• the suspension system 92 comprises the coil former 107, a first portion 130 of the coil former 107, the spider 111 with a concentric corrugation 119, the spacer 110, a groove 132 in the output disk 112, a viscous magnetic fluid 134, and the antifriction bearing 104.
• the first portion 130 of the coil former is radially suspended by the spider 111 which is disk shaped in the preferred embodiment.
• the spider 111 may contain a concentric corrugation 119 that provides additional compliance by the coil former 107 in the axial direction.
• the concentric corrugation 119 will also permit additional axial displacement. This additional displacement is required for improving the low frequency response, or alternatively increased sound pressure level.
• the spacer ring 110 comprises means for attaching a distal portion 138 of the spider suspension 111.
• Means for attaching the distal portion 138 of the spider 111 to the spacer 110 can be through oveimolding, ultrasonic welding or other bonding or mechanical methods.
• spider and spacer can be integrally associated as a single element.
• the antifriction bearing 104 has a first face 140 in intimate contact with the second wall 109 of the gap 124.
• An upper surface 142 of the bearing 104 is in intimate contact with the lower edge 115 of the permanent magnet 105 and a lower surface 144 is in contact with the bottom wall 116 of the channel 103.
• a second face 146 of the bearing 104 is facing a first inner surface 148 of the coil former 107.
• the bearing 104 of the preferred embodiment is made from a low friction material such as Teflon® by DuPont or similar material.
• the acoustic output of the present invention is to the output disk 112 and best shown in Figs. 2 and 3.
• the output disk 112 comprises a groove 132 in which the coil former 107 is bonded.
• the output disk 112 serves to stabilize the thin wall coil former from transverse radial forces between the coil former 107 and the output disk 112.
• the output disk 112 is a lightweight component to preferentially increase the velocity of the output disk 112 relative to the core 101 based on the relative mass.
• the output disk 112 may be attached mechanically or adhesively to a soundboard.
• a second portion 149 of the coil former 107 may be radially suspended by the viscous magnetic fluid 134.
• the magnetic fluid 134 is held in suspension by the resulting magnetic flux from the permanent magnet 105.
• the magnetic fluid will provide a radial restoring force if the coil former 107 is radially displaced in the magnetic gap 124.
• the antifriction bearing 104 is provided for the coil 106 to land upon if a large radial force is imparted to the coil former 107 causing large radial displacements. The bearing 104 will prevent the coil former 107 from striking or rubbing the magnet 105 or the outer wall 108 of the channel 103.
• Figs. 4, 5 and 6 depict an integrated mounting apparatus of one embodiment.
• the output disk 112 and its receiver 114 and means for interlocking them are shown.
• each tab element 152 is generally spaced equidistant from other tab elements.
• the receiver 114 of this embodiment has an annular hole 160 with a depth 162 and a base 164.
• a protruding segmented wall 250 is characterized by an inner surface 161 and at least one and preferably a plurality of openings 251.
• the openings 251 comprise an adjacent opening 253 having a vertical wall 253a.
• one of said plurality of tab elements 152 on said distal surface 150 is inserted fully in opening 251 whereupon the output disk 247 is rotated such that the tab element 152 is moved in the adjacent opening 253 to engage the vertical wall 253a which frictionally engages the receiver 114 and the output disk 247 and serves to transmit sound vibrations as well as mount the unit on the sound body.
• the plurality of tab elements 152 comprise segmented helical wedges.
• Each of said plurality of segmented helical wedges 152 tapers from a first leading edge 154 to a second trailing edge 156.
• Each of said plurality of segmented wedges is generally spaced equidistant from others.
• the openings 251 are flanked by angled receiving surfaces 252 which ease accurate placement of said segmented helical wedges 152.
• Each of said plurality of openings 251 in this second embodiment comprises an adjacent helicoidal opening 253 with a surface 170 complementarily shaped to the segmented helical wedges 152.
• the receiver 114 is mounted on a soundboard by conventional means.
• the wedges on the output disk 247 on the voice coil actuator 90 are then aligned with the openings 251 on the receiver.
• the voice coil actuator is moved toward the receiver 114 such that the engagement wedges are in a position to rotationally engage helicoidal openings 253 and the surfaces 170.
• the voice coil actuator assembly 90 is rotated a partial turn which frictionally engages the receiver 114 and the output disk 247 and serves to transmit sound vibrations as well as mount the unit on the sound body.
• the distal surface 400 of the output disk can be convex as shown in Fig. 6a. As the output disk is compressed downward during installation, the convexity will flatten and disperse the downward forces more evenly.
• the output disk is removably engaged with the receiver 114 using the tab elements 152.
• locking means are employed.
• Said locking means comprises at least one protrusion 284 on said distal surface 150 and at least one rib-like element 285 on said inner surface 161 of said segmented wall 250.
• Said at least one protrusion 284 is positioned relative to one of said at least one rib-like elements 285 such that, upon insertion of each tab 152 into one of said openings 251 and rotating said output disk to engage said tab and the vertical wall 253a in said adjacent opening 253, the distal surface 150 flexes inward enough to allow the protrusion 284 to move past said rib-like element 285. By virtue of resilience or memory, said distal surface 150 then returns the protrusion to its extended position thereby frictionally preventing the output disk from counter rotating.
• the locking means comprises at least one locking snap wedge 184 comprising a curved sloped wedge surface 183 which when engagably rotated into receiver 114 will deflect inward until said locking snap wedge 184 attains a recess 185 in the protruding segmented wall 250 At this point the locking snap wedge 184 finds relief to the inward deflection and springs into the recess 185 where a locking surface 186 engages said wall 250 which prevents the output disk from counter rotating. As shown in FIG. 6a and FIG.
• At least one wedge 152a and preferably two wedges 152a arranged in opposition are hinged by way of dedicated flexural hinges 182 associated with said distal surface 150 and openings 181 in said distal surface 150 of said output disk which permit inward deflection of the locking snap wedge 184.
• release tabs 187 are provided in an opposed position. Compressing release tabs 187 deflect the portion of the distal surface 150 between the openings 181 and cause the locking snap wedges 184 to deflect inward disengaging the locking snap wedges 184 and permitting counter rotation of the voice coil actuator 90 for easy removal.
• FIG.7 An alternative coil former suspension is shown in FIG.7.
• the electrical current conductive coil 106 is wound on a coil former 107 that mechanically couples the electro- dynamic force into the desired acoustic structure.
• the coil former 107 in this configuration uses multiple spider suspension 111 and 11 Ia elements to radially align the coil former 107 with the magnetic gap 124.
• the spider elements permit axial displacement of the coil former 107 while restricting rocking motion or other out of plane motions that will cause the coil former 107 to strike or rub the permanent magnet 105 or the outer wall 108 of the channel 103.
• the integrated mounting apparatus includes output disk 112 comprising an annular hole 310.
• Said output disk 112 is attached to a soundboard member 306 by means of a clamping mechanism 302.
• Co-axially located with and generally covering the annular hole 310 of the output disk 112 is at least one high frequency speaker element 301.
• Said at least one high frequency speaker element 301 is mounted in such a manner that the acoustic output side 312 of each said speaker element 301 is facing the preferred direction for transmitting the acoustic response of the high frequency element of the system.
• a vibration isolation pad 304 may be positioned to be in communication with said output disk 112 and with each said high frequency element 301. The pad 304 will reduce the dynamic mass experienced by the voice coil actuator and minimize the structural vibration each high frequency speaker element 301.
• Each said at least one high frequency speaker element 301 is positioned relative to the output disk 112 such that it penetrates through the soundboard 306 to minimize the protrusion of the high frequency speaker element 301 from the face of the soundboard 306.
• the speaker element 301 may be mechanically fixated through conventional means to either the soundboard 306 or the output disk 112.
• This embodiment may also include the co-location of a plurality of high frequency speaker elements 301 mounted on a fixture 305 to fixedly position the high frequency speaker elements in relationship to each other.
• Acoustic radiation from a speaker element typically shows a focusing of the energy as the excitation frequency of the speaker element is increased.
• the elements are arranged generally so that the main response axes of the elements are not parallel. This may be accomplished through many orientations.
• a hemi-spherical arrangement drives the high frequency elements 301 in phase so that it behaves in similitude with a pulsating sphere.
• the acoustic soundboard 306 in this instance acts as a baffle, increasing the overall efficiency of the system.
• the inertial type voice coil actuator illustrated in the drawings is to be viewed as having some important advantages, including improved force density, power rating and relatively constant sound quality, due to the radially polarized permanent magnets, uniform magnetic field, and heat dissipating characteristics of the magnetic viscous fluid and linear bearing system. In addition, advantages of simplified installation elements and high frequency response capability have been incorporated.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

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• 2005
  • 2005-12-12 EP EP05853729A patent/EP1969899A4/de not_active Withdrawn
  • 2005-12-12 CA CA002637692A patent/CA2637692A1/en not_active Abandoned
  • 2005-12-12 WO PCT/US2005/044881 patent/WO2007070025A1/en active Application Filing
  • 2005-12-12 AU AU2005339167A patent/AU2005339167A1/en not_active Abandoned

Patent Citations (2)

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