US3573397A - Acoustic diaphragm and translating device utilizing same - Google Patents

Acoustic diaphragm and translating device utilizing same Download PDF

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Publication number
US3573397A
US3573397A US638926A US3573397DA US3573397A US 3573397 A US3573397 A US 3573397A US 638926 A US638926 A US 638926A US 3573397D A US3573397D A US 3573397DA US 3573397 A US3573397 A US 3573397A
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United States
Prior art keywords
diaphragm
armature
translating device
reinforcement
acoustic
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US638926A
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English (en)
Inventor
Joseph A Sawyer
George C Tibbetts
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Tibbetts Industries Inc
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Tibbetts Industries Inc
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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
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/16—Mounting or tensioning of diaphragms or cones
    • H04R7/18—Mounting or tensioning of diaphragms or cones at the periphery
    • H04R7/20—Securing diaphragm or cone resiliently to support by flexible material, springs, cords, or strands

Definitions

  • An acoustic diaphragm means for a translating device comprises a diaphragm portion and a surround therefor, a flexural pivot pin that extends substantially perpendicular to the diaphragm portion and attaches the diaphragm portion to the translating device near one edge of the diaphragm portion, and means for connecting another portion of the diaphragm portion to the vibratable element of the translating device, away from the center of pressure of the diaphragm means.
  • the diaphragm utilized with a translating device provides a very high degree of acoustic compliance which enables the armature to be made thicker, and also permits the diaphragm to be connected to the armature other than at the PATENTEU APR 5 I97! SHEET 2 [IF 2 ACOUSTIC DIAPHRAGM AND TRANSLATING DEVICE UTILIZING SAME BACKGROUND OF THE INVENTION
  • the diaphragm of this invention is particularly useful with a miniaturized trari'slatingdevice. More specifically, it may be employed in an electroacoustic transducer utilized in hearing aids. Such transducers, which are bilateral in operation, may be used as microphones to convert acoustic energy to an electrical signal or as receivers to convert electrical energy to acoustic energy.
  • Electroacoustic transducers are being miniaturized for use with electronic amplifiers of very small size, in hearing aids that may be small enough to fit well within the pinna of the ear of the user and to extend into a substantial portion of the external auditory meatus. As the size of the transducer is reduced, new structures must be created to obtain optimum performance in reduced size.
  • diaphragm of the electroacoustic transducer One element of particular concern is the diaphragm of the electroacoustic transducer.
  • Such diaphragm must permit the associated transducer to be fabricated easily in very small size, and it must utilize the shape and size of such transducer to best advantage.
  • the diaphragm must be able to be attached to the freely vibrating portion of the active element of the transducer at an optimum position near the point of maximum excursion of the vibrating portion, with no detrimental effect on the size or performance of the transducer.
  • the diaphragm means may comprise a-laminate sheet of plastic and metal, with part of the sheet defining a diaphragm portion, another part defining a compliant surround etched free of metal, and a third part defining a support area exterior of the surround.
  • the support area is secured to a frame attached to the housing of the translating device, and the center of pressure of the diaphragm portion is connected by a drive pin to a portion of the armature near its free end.
  • the center of acoustic pressure must coincide with the central drive point and thus it is not possible to have the diaphragm portion utilize the entire geometrical area available.
  • the diaphragm is square (symmetrical about the drive point) and located near one end of the rectangular frame, with a portion of the frame occupying an area that could otherwise be utilized by the diaphragm portion if the center of acoustic pressure did not have to coincide with the drive point.
  • an acoustic diaphragm pivotally attached by a substantially perpendicular flexural pivot pin to a support member near one edge of the diaphragm, with a drive pin connected near the opposite edge of the diaphragm on the other side of and away from the center of pressure of the diaphragm.
  • the drive pin leads to and is connected to the vibratable element of a translating device at one edge portion thereof, with the vibratable element extending substantially parallel to the diaphragm from the drive pin toward the pivotal attachment.
  • Such diaphragm permits the associated translating elements and overall electroacoustic translating device to be fabricated more easily and in very small sizes, including fabrication in elongate shapes of very small cross section.
  • the diaphragm is useful with translating devices that utilize to best advantage the shape and size constraints on devices applicable in practice.
  • the pivoted diaphragm eliminates a spurious mode of vibration, and enables greater utilization of the available geometrical area since the center of acoustic pressure does not have to coincide with the drive point.
  • Such diaphragm when utilized with an end-driven translating device provides high acoustic compliance and, in receiver embodiments, an acoustic volume displacement equal to or better than that obtained with a conventional translating device with a diaphragm driven at its geometric center. Due to the nature of the present system, its resistance to damage by shock is better than that of the more conventional type of electroacoustic translating devices, and its accelerometer sensitivity is less.
  • FIG. 1 is a side sectional view of a general representation of the diaphragm of this invention
  • FIG. 2 is another side sectional view similar to FIG. 1 with a drive pin in a different position;
  • CFIG. 3 is an exploded perspective view of a magnetic-type electroacoustic transducer utilizing a diaphragm according to the invention.
  • FIG. 4 is a side view of a general representation of prior diaphragms showing a mode of vibration that may be undesirable when not constrained.
  • FIG. I shows a general representation of a diaphragm means I comprising a diaphragm portion or reinforcement 2 and a flexible surround 3 connected to the periphery of the diaphragm reinforcement and to a supporting means shown generally at 4.
  • diaphragm portion 2 is pivotally attached near one edge to a supporting means 5 by any suitable means such as a hinge, but preferably is connected by a flexural pivot 6 to means 5.
  • a drive pin or connecting pin 7 is attached to the diaphragm reinforcement on the other side of and away from the center of pressure of the diaphragm, which may be near one edge of the diaphragm reinforcement 2 as shown.
  • the connecting pin is not as near to the edge of the diaphragm reinforcement.
  • Connecting pin 7 leads to and is connected to the vibratable element 8 of a translating device which operates in flexure or torsion, preferably at or near one edge 'such as the end thereof.
  • the vibratable element extends substantially parallel to the diaphragm from the connecting pin 7 toward the pivotal attachment 6, and may be attached to a portion of supporting means 5 such as in the vicinity of flexural pivot 6.
  • Pivoting the diaphragm near one edge to a supporting means enables the diaphragm reinforcement to function substantially as a lever.
  • sound waves drive the diaphragm portion over its entire area, and can be treated as a force b applied at the center of pressure of the diaphragm reinforcement at a distance a from the flexural pivot 6.
  • Driving force Y can be taken off the diaphragm reinforcement at any desired distance x from the pivot 6, with the diaphragm reinforcement functioning substantially as a lever.
  • the driving force available and the amplitude of movement vary linearly with change of distance from the pivot point. As the distance x increases the amplitude of movement increases and the driving force y decreases.
  • the stiffness s of the vibratable element 8 of the translating device is inversely proportionalgto the cube of t, where I is the distance from the point of attachment of element 8 at supporting means 5 along element 8 to connecting pin 7.
  • I is the distance from the point of attachment of element 8 at supporting means 5 along element 8 to connecting pin 7.
  • the stiffness decreases at an ever-increasing nonlinear rate, much faster than the linear decrease of driving force y.
  • a net gain in acoustic compliance first appears. The greatest-gain results when the vibratable element 8 is driven at its extreme end.
  • That acoustic compliance can be made equal to the acoustic compliance of the assumed conventional case by increasing the thickness of the armature by the cube root of 2, and therefore the diaphragm of this invention allows an armature thicker by this factor when designing for a specified acoustical compliance of the combination.
  • the thicker armature provides increased flux-carrying capability.
  • the end-driven configuration does not require an aperture through the armaturefor the drive pin, and thus the flux-carrying capability of the armature is also increased for that reason.
  • the thicker armature has an increased stiffness, and a deflection that would be reduced except that the change of location of forces compensates for the otherwise reduced deflection and provides an amplitude of deflection at the end of the end-driven armature slightly more than twice that of the deflection at the midpoint of the conventional case.
  • the pivoted diaphragm divides out the factor 2, leaving an estimate that the end-driven armature configuration produces, in a receiver embodiment, a slightly increased volume displacement over that provided by the conventional configuration. Because of the many variables indicated above, it is difficult to estimate the exact amount of increase of volume displacement.
  • the end-driven configuration has a clear advantage in its increased resistance to damage by mechanical shock, because the armature can be thicker as noted above. Furthermore, as stated above the end-driven configuration does not need an open aperture in the annature which acts as a stress concentrator, and the armature without an an aperture is thus more resistant to mechanical shock.
  • the mass of the armature in the end-driven configuration is greater than that in the midpoint-driven configuration.
  • the increased mechanical stiffness more than compensates for this added mass, and therefore the accelerometer sensitivity will be less than that of the conventional configuration.
  • a diaphragm according to the invention may be utilized with a magnetic-type transducer such as that disclosed in copending application Ser. No. 638,878 of George C. Tibbetts et al. filed of even date.
  • a diaphragm means of the type disclosed in US. Pat. 3,166,148 of George C. Tibbetts is employed, and may comprise a diaphragm portion 9, a diaphragm surround 10, and a self-frame 11 having a peripheral rim 12.
  • the diaphragm portion 9 may have flats l3 and 14, and between the flats the diaphragm portion may be formed so as to increase greatly the flexural stiffness of the diaphragm portion.
  • the form may correspond to a continuous trough generated by a portion of a sphere the projection of whose center follows a contour between flats 13 and 14.
  • a frame 15 has a peripheral rim 16, an aperture defined by edge 17, and a formed boundary 18 adjacent the aperture.
  • the diaphragm peripheral rim 12 fits within rim 16 and boundary 18 of the frame and is bonded and sealed together therewith by adhesive.
  • Flexural pivot 19 connected to the magnetic translating device 24 extends up through aperture 20 in flat l3 and is attached to the diaphragm portion by an adhesive mass, not shown for the sake of clarity.
  • Connecting pin 21 connected to the end 27 of the armature 26 extends up through aperture 22 in flat l3 and is similarly attached thereto by an adhesive mass not shown.
  • the diaphragm is protected and a space above the diaphragm is provided by a cover 23 which is located by rim 16 of the frame 15.
  • a cover 23 which is located by rim 16 of the frame 15.
  • the cover is fitted in place, and the adhesive bonds the cover to the frame and to the sleeve and serves also to seal the frame to the sleeve.
  • the frame 15 and cover 23 may be fabricated from magnetic material to provide magnetic shielding against stray flux traversing the apertures in the sleeve containing the flexural pivot 19 and connecting pin 21.
  • the remainder of the structure shown in FIG. 3 comprises the magnetic transducer 24 disclosed in said copending application of George C. Tibbetts et al., and includes a sleeve 25 of magnetic material, an armature 26 having an end 27 to which is attached connecting pin 21, a coil 28, a magnet stack 29, a
  • the electroacoustic transducer of FIG. 3 may function as either a microphone or a receiver.
  • sound pressure may have access to the space between the diaphragm and cover by an aperture through the cover or by passage from the end of the transducer through appropriate conduits and chambers to said space.
  • the diaphragm will be actuated by such sound pressure and will pivot about the end due to attachment to flexural pivot 19.
  • the other end of the diaphragm will move connecting pin 21 which in turn actuates the armature 26.
  • the armature can be thicker than in conventional transducers as noted above, and will have flux induced along its length by movement in the working gap of magnet stack 29,7 which flux will induce in E.M.F. in coil 28 led to the output terminals 32.
  • the connecting pin is attached to a portion of the armature inwardly of the end and extends up in a space between the coil and the magnet stack. That space is in addition to the space between the magnet stack and the end of the casing, necessary to prevent shorting the magnet stack.
  • the connecting pin could not be of yoke form as in prior structure such as shown in FIG. 5 of US. Pat. No. 2,994,016 of Raymond W. Tibbetts et al., but due to the nature of the assembly had to be a straight pin extending through a hole in the armature.
  • the connecting pin may be attached to the end of the armature at the point of greatest compliance, with no hole through the armature, and no extra space is provided for the pin since it utilizes the space necessary to prevent shorting the magnet stack.
  • the coil and magnet stack can be compacted together.
  • this may be made a subassembly before insertion into the sleeve, simplifying the overall assembly process.
  • FIG. 4 shows a generalized form of the prior art diaphragm having a central drive pin.
  • a flexible surround (not shown) substantially prevents translation of the diaphragm reinforcement 33 to the right or left of the figure, but provides very little restraint against rotation about the point of attachment to the connecting pin 34, as shown in dotted lines.
  • the connecting pin flexes, as also shown in dotted lines.
  • FIG. 4 the rotation is shown relative to an undeflected armature, illustrating that in prior art devices a hitherto unrecognized mode of vibration, i.e. an extra degree of freedom, exists in general.
  • a mode of this type can absorb or reflect mechanical energy, and may and commonly does cause frequency response distortion within the passband of the transducer.
  • the rotation of the diaphragm reinforcement is not undesirable in itself; in this invention the diaphragm operates in rotation about the pivotal point. What may be undesirable is the situation in which the diaphragm is free to rotate irrespective of the motion of the armature.
  • the rotation of the diaphragm is in one-to-one correspondence with the vertical deflection of the end of the armature, insofar as the diaphragm can be considered to be a rigid body. It follows'that the extra degree of freedom has been substantially removed.
  • An acoustic diaphragm means for a translating device having a vibratable element comprising a diaphragm portion and a surround therefor, means attached to the diaphragm portion away from the center of pressure thereof for connection to said vibratable element, and a flexural pivot pin near one edge of the diaphragm portion and extending substantially perpendicular therefrom for pivotal support thereof, said diaphragm portion being thereby restricted to rotary movement about said pivot pin.
  • connection means is on the other side of the center of pressure of the diaphragm portion away from the flexural pivot pin.
  • An acoustic transducer comprising a translating device having a vibratable element, diaphragm means comprising a diaphragm reinforcement and a surround therefor, means connecting said diaphragm reinforcement to said vibratable element away from the center of pressure of the diaphragm reinforcement, and a flexural pivot pin extending substantially perpendicular from, and pivotally attaching one edge of, said diaphragm reinforcement to said translating device, said diaphragm reinforcement being thereby restricted to rotary movement about said pivot pin.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
US638926A 1967-05-16 1967-05-16 Acoustic diaphragm and translating device utilizing same Expired - Lifetime US3573397A (en)

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US63892667A 1967-05-16 1967-05-16

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US (1) US3573397A (fr)
BE (1) BE715074A (fr)
CH (1) CH490778A (fr)
DE (1) DE1762264A1 (fr)
FR (1) FR1565243A (fr)
GB (1) GB1234275A (fr)
LU (1) LU56088A1 (fr)
NL (1) NL6806732A (fr)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126769A (en) * 1976-10-11 1978-11-21 Microtel B.V. Moving armature transducer with reinforced and pivoted diaphragm
US4373781A (en) * 1979-02-12 1983-02-15 Gte Laboratories Incorporated Acoustic to optical pulse code modulating transducer
GB2229339A (en) * 1989-03-14 1990-09-19 Microtel Bv Acoustic transducer
EP0851710A1 (fr) * 1996-12-23 1998-07-01 Microtronic Nederland B.V. Transducteur électroacoustique
US6075870A (en) * 1996-12-02 2000-06-13 Microtronic B.V. Electroacoustic transducer with improved shock resistance
US6385327B1 (en) * 1998-06-16 2002-05-07 U.S. Philips Corporation Device having two coaxially disposed bodies which are movable relative to one another along a translation axis
US20030063768A1 (en) * 2001-09-28 2003-04-03 Cornelius Elrick Lennaert Microphone for a hearing aid or listening device with improved dampening of peak frequency response
US6658134B1 (en) 1999-08-16 2003-12-02 Sonionmicrotronic Nederland B.V. Shock improvement for an electroacoustic transducer
US6739425B1 (en) * 2000-07-18 2004-05-25 The United States Of America As Represented By The Secretary Of The Air Force Evacuated enclosure mounted acoustic actuator and passive attenuator
US20050111688A1 (en) * 1999-04-06 2005-05-26 Engbert Wilmink Electroacoustic transducer with a diaphragm and method for fixing a diaphragm in such transducer
US20060093167A1 (en) * 2004-10-29 2006-05-04 Raymond Mogelin Microphone with internal damping
US7110565B1 (en) 1999-04-06 2006-09-19 Sonionmicrotonic Nederland B.V. Electroacoustic transducer with a diaphragm, and method for fixing a diaphragm in such transducer
US20090034780A1 (en) * 2007-07-30 2009-02-05 John Joseph Gaudreault Diaphragm for full range boxless rotary loudspeaker driver
US20180206041A1 (en) * 2015-07-29 2018-07-19 Sony Corporation Acoustic conversion apparatus and sound output equipment

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013221752A1 (de) * 2013-10-25 2015-04-30 Kaetel Systems Gmbh Ohrhörer und verfahren zum herstellen eines ohrhörers
US10959024B2 (en) * 2018-09-27 2021-03-23 Apple Inc. Planar magnetic driver having trace-free radiating region

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1072477A (en) * 1910-05-18 1913-09-09 Victor Talking Machine Co Acoustical instrument.
US2927977A (en) * 1958-11-17 1960-03-08 Sonotone Corp Acoustic signal transducers
US3251954A (en) * 1961-10-27 1966-05-17 Industrial Res Prod Inc Electroacoustic transducer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1072477A (en) * 1910-05-18 1913-09-09 Victor Talking Machine Co Acoustical instrument.
US2927977A (en) * 1958-11-17 1960-03-08 Sonotone Corp Acoustic signal transducers
US3251954A (en) * 1961-10-27 1966-05-17 Industrial Res Prod Inc Electroacoustic transducer

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126769A (en) * 1976-10-11 1978-11-21 Microtel B.V. Moving armature transducer with reinforced and pivoted diaphragm
US4373781A (en) * 1979-02-12 1983-02-15 Gte Laboratories Incorporated Acoustic to optical pulse code modulating transducer
GB2229339A (en) * 1989-03-14 1990-09-19 Microtel Bv Acoustic transducer
US6075870A (en) * 1996-12-02 2000-06-13 Microtronic B.V. Electroacoustic transducer with improved shock resistance
EP0851710A1 (fr) * 1996-12-23 1998-07-01 Microtronic Nederland B.V. Transducteur électroacoustique
NL1004877C2 (nl) * 1996-12-23 1998-08-03 Microtronic Nederland Bv Elektroakoestische transducent.
US6078677A (en) * 1996-12-23 2000-06-20 Microtronic Nederlands B.V. Electroacoustic transducer with improved diaphragm attachment
US6385327B1 (en) * 1998-06-16 2002-05-07 U.S. Philips Corporation Device having two coaxially disposed bodies which are movable relative to one another along a translation axis
US20060230598A1 (en) * 1999-04-06 2006-10-19 Wilmink Engbert Method for fixing a diaphragm in an electroacoustic transducer
US20050111688A1 (en) * 1999-04-06 2005-05-26 Engbert Wilmink Electroacoustic transducer with a diaphragm and method for fixing a diaphragm in such transducer
US7706561B2 (en) 1999-04-06 2010-04-27 Sonion Nederland B.V. Electroacoustic transducer with a diaphragm and method for fixing a diaphragm in such transducer
US7492919B2 (en) 1999-04-06 2009-02-17 Sonion Nederland B.V. Method for fixing a diaphragm in an electroacoustic transducer
US7110565B1 (en) 1999-04-06 2006-09-19 Sonionmicrotonic Nederland B.V. Electroacoustic transducer with a diaphragm, and method for fixing a diaphragm in such transducer
US6658134B1 (en) 1999-08-16 2003-12-02 Sonionmicrotronic Nederland B.V. Shock improvement for an electroacoustic transducer
US6739425B1 (en) * 2000-07-18 2004-05-25 The United States Of America As Represented By The Secretary Of The Air Force Evacuated enclosure mounted acoustic actuator and passive attenuator
US20030063768A1 (en) * 2001-09-28 2003-04-03 Cornelius Elrick Lennaert Microphone for a hearing aid or listening device with improved dampening of peak frequency response
US7065224B2 (en) 2001-09-28 2006-06-20 Sonionmicrotronic Nederland B.V. Microphone for a hearing aid or listening device with improved internal damping and foreign material protection
US7415121B2 (en) 2004-10-29 2008-08-19 Sonion Nederland B.V. Microphone with internal damping
US20060093167A1 (en) * 2004-10-29 2006-05-04 Raymond Mogelin Microphone with internal damping
US20090034780A1 (en) * 2007-07-30 2009-02-05 John Joseph Gaudreault Diaphragm for full range boxless rotary loudspeaker driver
US7860265B2 (en) * 2007-07-30 2010-12-28 John Joseph Gaudreault Diaphragm for full range boxless rotary loudspeaker driver
US20180206041A1 (en) * 2015-07-29 2018-07-19 Sony Corporation Acoustic conversion apparatus and sound output equipment
US10587959B2 (en) * 2015-07-29 2020-03-10 Sony Corporation Acoustic conversion apparatus and sound output equipment

Also Published As

Publication number Publication date
DE1762264A1 (de) 1970-04-16
GB1234275A (fr) 1971-06-03
DE1762264B2 (fr) 1970-10-29
BE715074A (fr) 1968-11-13
LU56088A1 (fr) 1969-02-10
NL6806732A (fr) 1968-11-18
FR1565243A (fr) 1969-04-25
CH490778A (fr) 1970-05-15

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