US2164374A - Sound reproducing device - Google Patents

Sound reproducing device Download PDF

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Publication number
US2164374A
US2164374A US49945A US4994535A US2164374A US 2164374 A US2164374 A US 2164374A US 49945 A US49945 A US 49945A US 4994535 A US4994535 A US 4994535A US 2164374 A US2164374 A US 2164374A
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United States
Prior art keywords
diaphragm
coil
conductor
air gap
ring
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Expired - Lifetime
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US49945A
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English (en)
Inventor
Barker Alfred Cecil
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Individual
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Individual
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    • 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
    • H04R9/02—Details
    • H04R9/04—Construction, mounting, or centering of coil
    • 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 
    • H04R1/24—Structural combinations of separate transducers or of two parts of the same transducer and responsive respectively to two or more frequency ranges

Definitions

  • This invention relates to electro-mechanical apparatus of the electrodynamic type for the interchange of electrical vibrations into mechanical movement and vice versa and more particu- 5 larly to acoustic apparatus such as loudspeakers,
  • the invention has for its object to provide a loudspeaker or the like which has an extended frequency response and is capable of reproducing adequately both low and high audio frequencies.
  • two connected coils 35 have been attached to different parts of the same diaphragm and arranged in separate air gaps of the magnetic assembly, or two diaphragms of different sizes have been attached to one coil.
  • a loudspeaker embodying the present invention two coils are employed. Only one of these, however, is connected to the circuit supplying energy to the loudspeaker, and this coil is attached to the diaphragm not directly but through a resilient coupling in such a manner that the 5 diaphragm is capable of slight movement relative to this coil.
  • the other coil is a much lighter coil, preferably consisting of a single turn or a ring of aluminium or other high conductivity material inductively coupled with the first coil and is directly attached to the diaphragm.
  • the present invention consists broadly of an actuating element for an electrodynamic reproducer comprising two moving conductors having a resilient coupling between them, wherein the two conductors are inductively coupled so that one conductor has current generated therein from the other.
  • the invention also consists of an electrodynamic reproducer comprising a diaphragm or the like, a moving conductor rigidly connected thereto and a second moving conductor resiliently connected therewith, the two conductors being inductively coupled.
  • Figures 1 to 7 are each fragmentary sections of the diaphragm, actuating element and pole piece arrangement of an electrodynamic loudspeaker, while Figure 8 is a corresponding section of an electrodynamic microphone.
  • a moving coil Iii which may be of a single turn of strip conductor or a number of turns of wire is wound upon a thin paper support ll of preferably not substantially greater length than is necessary to support the coil I 6.
  • the coil so wound is then attached to a preformed ring [2 of very thin aluminium, of the order of 5 mils thick.
  • a ring of such thin material it is difiicult to obtain a tube with such thin walls, particularly as the tube should preferably be seamless. Further, difficulty is encountered in cutting lengths from a tube with walls so thin and so far it has been found 40 most satisfactory to stamp aluminium foil into a cup and then to remove the base of the cup.
  • the aluminium ring l2 may, however, be desirable to form the aluminium ring l2 by applying the metal foil to paper by a metal spraying or electroplating process or to employ other methods, but it is necessary that the ring so formed should have the ends thereof joined to form a closed electrically conducting circuit.
  • the ring is suitably shaped at its one end to facilitate its connection to the diaphragm I3 of the apparatus.
  • the attachment of the ring so formed to the coil is effected through a resilient coupling device.
  • rubber bands I4 are employed, but it should be pointed out that care is necessary in the selection of the rubber.
  • the operating coil of a loudspeaker of this type may reach a comparatively high temperature when in use and as the rubber is very closely arranged to the coil it must be of a quality which will retain its resilience at temperatures of the order of Fahrenheit.
  • a suitable anti-oxidizing agent may be included in the rubber to assist in attaining this object.
  • the resilient coupling is preferably formed by applying the rubber, where this is employed, to the exterior surface of the aluminium ring.
  • a continuous coating because of the comparative closeness of the two parts between which it is arranged, is found in some cases to be too rigid and I therefore prefer to have two spaced bands 14 of rubber applied to the aluminium ring.
  • These bands of rubber are not entirely satisfactory when made by the usual methods, and they are more suitably made by dipping, using a glass mandrel, by painting or by electro-deposition, and they may be formed directly upon the aluminium ring.
  • the bands When made separately before being applied to the aluminium ring, the bands are retained upon the ring by their own resilience.
  • the rubber should not be under appreciable tension, since this causes deterioration of the rubber. If an adhesive of a rubber solution is employed, it is very important that the adhesive and the rubber should have the same ageing characteristic.
  • the ring with the rubber bands applied, is a close fit within the wound coil, and the ring is expanded slightly to cause it to be securely attached to the coil. This may be done by spinning, or by an expanding mandrel. Alternatively a close-fitting rubber stopper may be inserted in the ring and then compressed to produce the desired expansion of the ring.
  • the ring and coil thus attached are secured to the diaphragm of the apparatus, which is preferably of the usual conical type.
  • the diaphragm assembly is mounted, together with the usual centering spider, terminals and so forth in the annular air gap between the poles N5 of a magnetic circuit which may be of conventional form. Current is fed only to the wound coil, which drives the diaphragm through the resilient coupling and also induces currents in the ring, which is directly coupled to the diaphragm.
  • felt is used as the resilient material.
  • the ring l2, diaphragm l3 and centering spider [5 are secured together and the moving coil Ill, wound on its paper support H, is arranged as a free fit upon the ring 12.
  • An annulus ll of felt is attached to the ring or the spider or both by adhesive and the end of the paper support, bent outwardly to form a flange l8 at right angles to the axis of the coil, is attached by adhesive to the felt annulus II. There should be a clearance between the coil and the ring to avoid chatter.
  • the centering spider I5 which serves to locate the coil accurately within the annular air gap is attached directly to the diaphragm H or to the ring l2 which is secured thereto.
  • the aluminium ring attached d rectly to the cone is located within the paper support by the rubber bands as previously described. The damping effect of the spider at the highest frequencies is therefore decreased as it is connected to the cone only through the resilient coupling.
  • the diaphragm itself provides the resilient coupling.
  • the spider l5 which, as in the other embodiments of the invention, may be an inside spider
  • the cone l3 and ring l2 are secured together and the paper support for the coil II is provided with the outwardly extending flange 18, the periphery of which is attached to the diaphragm l5 by adhesive at a point some distance from the point at which the ring is secured. Clearance between the ring and the coil is necessary in this case also.
  • the coil may be arranged in two parts, and such a construction is shown in Figure 6 of the accompanying drawings.
  • the aluminium ring l2, cone l3, and spider 15 are arranged in a manner similar to that described with reference to Figure l.
  • the ring I2 is, however, provided with rubber bands Ma, Mb or like resilient couplings on both the inside and outside, to which are secured by suitable adhesive the paper supports Ila, llb for the coils Mia and I017.
  • These coils Ella and ID?) may be fed in series or parallel from a single circuit or independently from separate circuits.
  • FIG. '7 of the drawings is shown a further method of forming the resilient coupling between the coils which is found to be satisfactory in practice.
  • the paper support I I for the moving coil i6 is provided with two ridges or crimps 20. These ridges are of sufficient height as-to permit slight movement of that part of the support which lies between them and upon which the coil is disposed. More than two such crimps, which maydivide the coil into a number of sections, may be provided.
  • the ring l2 may suitably be shaped as indicated.
  • the moving conductor which is unconnected may be formed integrally with the diaphragm of the apparatus.
  • the combined ring and diaphragm may conveniently take the form shown in Figure 8, in which the ring and diaphragm are'in the form of a cup, of which the sides 12 are arranged in inductive relation to the moving coil Ill, but is separated therefrom by the resilient connection M or by one of the resilient couplings previously described, while the base l2a of the cup forms the diaphragm.
  • the coils H] and I2 move together in the magnetic field and thereby generate a voltage at the terminals of the coil.
  • the inertia of the coil I0 is sufficient to prevent adequate movement thereof, but the coil I2 is not so prevented andinduces in the coil I'll voltages which are'fed to the external circuit.
  • the frequency range of the device is appreciably extended.
  • the apparatus may be desirable to form the apparatus with a dust tight air gap, in which case the construction may be correspondingly added to or modified.
  • the closed circuit forming conductor is in all cases connected rigidly with the diaphragm, and that the cooperating audio frequency coil or conductor is inductively related to the first conductor and compliantly connected to the diaphragm, either through a compliant connection with the diaphragm or through a compliant connection between it and the first conductor.
  • the outer or audio frequency coil is comparable to the conventional diaphragm actuating coil wound with copper wire, and is adapted to be connected through suitable means to a source of audio frequency current.
  • the inner conductor is for convenience formed of a thin aluminium cylinder which can be rigidly cemented to the diaphragm.
  • the coupling between the closed circuit conductor and the audio frequency conductor is both mechanical and inductive, and as a result they produce a driving force upon the diaphragm which varies with the frequency of the current impressed upon the audio frequency coil.
  • the audio frequency excited conductor will drive the diaphragm through its compliant connection therewith, while at these low audio frequencies no appreciable current will be induced in the closed circuit forming conductor.
  • the mechanical driving forces provided for the diaphragm by the audio frequency coil will, because of the compliant connection, become less and less, and at the highest frequencies the audio frequency coil will remain practically stationary.
  • high frequency currents will be induced in the closed circuit forming conductor with increasing transfer efiiciency, and as a result of the compliant coupling, this conductor will respond to and drive the diaphragm at the higher frequencies.
  • the diaphragm actuating means here disclosed satisfies all of the requirements for successful operation, as it provides a strong driving force for reproduction of the low audio frequency signals when it must move as a whole, and a light moving system for the reproduction of'the high audio frequency signals.
  • An actuating element for the diaphragm of an electro-dynamic sound reproducer comprising two movable diaphragm actuating conductors disposed in inductive relation with each other in a magnetic air gap, one of said conductors forming a closed circuit being coupled directly to said diaphragm and having a resilient connection with the other conductor, whereby said other conductor will be compliantly connected through the first conductor to said diaphragm so that when said other conductor is energized the movable conductor which is directly connected to the diaphragm will drive the diaphragm in response to currents generated therein by induction from the other movable conductor.
  • an electrodynamic sound reproducing device the combination of a diaphragm, pole pieces forming a magnetic air gap adjacent said diaphragm, a metallic cylinder forming a closedcircuit conductor rigidly attached to said diaphragm and extending into said air gap, a coil supporting means connected to said cylinder, and a coil winding adapted to be excited with an audio frequency current compliantly mounted upon said coil supporting means and in inductive relation to said closed-circuit conductor.
  • an electrodynamic sound reproducing device the combination of a diaphragm, a pair of spaced magnetic poles forming an electromagnetic air gap adjacent said diaphragm, a current conducting cylinder forming a short-circuited conductor rigidly attached to said diaphragm and extending into said air gap, and an audio frequency current winding disposed in said air gap and compliantly mounted upon and in inductive relation with said current conducting cylinder.
  • a magnetic field frame having an annular air gap
  • a diaphragm mounted adjacent said air gap
  • a metallic cylinder rigidly attached to said diaphragm extending into said air gap and forming a short-circuited conductor
  • an audio frequency current coil disposed in said air gap
  • an electrodynamic sound reproducing device of the character described, the combination of a pair of spaced magnetic poles having an annular air gap therebetween, a diaphragm yieldingly supported adjacent said air gap, a metallic conductor rigidly secured to said diaphragm and forming a closed electrical circuit in said air gap, an audio frequency current winding disposed in concentric relation with the closed electrical circuit forming metallic conductor, and resilient means between said conductor and said winding for compliantly securing said Winding upon said conductor in said air gap.
  • an electrodynamic sound reproducing device of the character described, the combination of an inner and an outer magnetic pole piece having an annular air gap therebetween, a diaphragm yieldingly supported adjacent said air gap, a cylindrical metallic member secured to said diaphragm and extending into said air gap to form a closed-circuit conductor therein, an audio frequency current winding disposed concentrically in inductive relation along the inside of said cylindrical metallic member, a second current winding disposed in concentric relation outside of said cylindrical member, and resilient means between each of said windings and said cylindrical member for compliantly securing said windings in inductive relation upon said cylindrical member.

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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)
  • Toys (AREA)
  • Percussion Or Vibration Massage (AREA)
US49945A 1934-12-05 1935-11-15 Sound reproducing device Expired - Lifetime US2164374A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB34967/34A GB448271A (en) 1934-12-05 1934-12-05 Improvements in and relating to sound reproducing devices

Publications (1)

Publication Number Publication Date
US2164374A true US2164374A (en) 1939-07-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
US49945A Expired - Lifetime US2164374A (en) 1934-12-05 1935-11-15 Sound reproducing device

Country Status (5)

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US (1) US2164374A (enrdf_load_stackoverflow)
BE (1) BE412034A (enrdf_load_stackoverflow)
FR (1) FR796804A (enrdf_load_stackoverflow)
GB (1) GB448271A (enrdf_load_stackoverflow)
NL (1) NL44190C (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2538691A (en) * 1948-07-19 1951-01-16 Richard K Y Kim Voice coil for radio loud-speakers
US2556816A (en) * 1946-12-04 1951-06-12 Technicon Cardiograph Corp Polarized electromagnetic operator with damped coil armature
US2645684A (en) * 1948-06-30 1953-07-14 Rca Corp Noise discriminating system
US3792394A (en) * 1971-12-16 1974-02-12 J Bertagni Voice coil
US4201886A (en) * 1976-12-02 1980-05-06 Tenna Corporation Plural concentric moving coil speaker with push-pull voltage follower direct coupling
US4220832A (en) * 1976-12-02 1980-09-02 Tenna Corporation Two-way speaker with transformer-coupled split coil
US4297537A (en) * 1979-07-16 1981-10-27 Babb Burton A Dynamic loudspeaker
US5822444A (en) * 1995-12-06 1998-10-13 Pioneer Electronic Corporation Loudspeaker
US5933508A (en) * 1993-09-22 1999-08-03 Sony Corporation Horn speaker system
US6130955A (en) * 1997-03-20 2000-10-10 Harman Audio Electronic Systems Gmbh Voice coil assembly
US6904158B1 (en) * 1998-04-03 2005-06-07 Sony Corporation Speaker apparatus
US20130016872A1 (en) * 2011-07-12 2013-01-17 Strata Audio LLC Voice Coil Former Stiffener

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118398B (en) * 1982-04-14 1986-04-03 Boaz Elieli Moving coil electroacoustic transducers

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2556816A (en) * 1946-12-04 1951-06-12 Technicon Cardiograph Corp Polarized electromagnetic operator with damped coil armature
US2645684A (en) * 1948-06-30 1953-07-14 Rca Corp Noise discriminating system
US2538691A (en) * 1948-07-19 1951-01-16 Richard K Y Kim Voice coil for radio loud-speakers
US3792394A (en) * 1971-12-16 1974-02-12 J Bertagni Voice coil
US4201886A (en) * 1976-12-02 1980-05-06 Tenna Corporation Plural concentric moving coil speaker with push-pull voltage follower direct coupling
US4220832A (en) * 1976-12-02 1980-09-02 Tenna Corporation Two-way speaker with transformer-coupled split coil
US4297537A (en) * 1979-07-16 1981-10-27 Babb Burton A Dynamic loudspeaker
US5933508A (en) * 1993-09-22 1999-08-03 Sony Corporation Horn speaker system
US5822444A (en) * 1995-12-06 1998-10-13 Pioneer Electronic Corporation Loudspeaker
US6130955A (en) * 1997-03-20 2000-10-10 Harman Audio Electronic Systems Gmbh Voice coil assembly
US6904158B1 (en) * 1998-04-03 2005-06-07 Sony Corporation Speaker apparatus
US20130016872A1 (en) * 2011-07-12 2013-01-17 Strata Audio LLC Voice Coil Former Stiffener
US9143866B2 (en) * 2011-07-12 2015-09-22 Strata Audio LLC Voice coil former stiffener

Also Published As

Publication number Publication date
NL44190C (enrdf_load_stackoverflow)
GB448271A (en) 1936-06-05
BE412034A (enrdf_load_stackoverflow)
FR796804A (fr) 1936-04-16

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