US3905448A - Loudspeaker - Google Patents

Loudspeaker Download PDF

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Publication number
US3905448A
US3905448A US483154A US48315474A US3905448A US 3905448 A US3905448 A US 3905448A US 483154 A US483154 A US 483154A US 48315474 A US48315474 A US 48315474A US 3905448 A US3905448 A US 3905448A
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United States
Prior art keywords
suspension means
diaphragm
loudspeaker
carbon fibers
frame
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US483154A
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English (en)
Inventor
Hirotake Kawakami
Toshio Sasabe
Toshio Hirosawa
Naomi Sakai
Nobuyuki Arakawa
Kozo Kokubu
Kazumasa Abe
Toshiko Harashino
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Sony Corp
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Sony Corp
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Filing date
Publication date
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Publication of US3905448A publication Critical patent/US3905448A/en
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Expired - Lifetime legal-status Critical Current

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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
    • 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
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/12—Non-planar diaphragms or cones

Definitions

  • This invention relates to a dynamic, cone type loudspeaker, and more particularly to a loudspeaker with suspension means for supporting the cone from a frame.
  • the vibration system comprises a cylindrical bobbin, a voice coil wound around the cylindrical bobbin, a suspension means'or a damper suspending the bobbin from a cone-shaped frame and a cone-shaped diaphragm fixed adhesively on the upper end of the bobbin.
  • An annular suspension means has its outer edge bonded to the upper end of the frame with a suitable binder and has its inner edge bonded to the upper end of the diaphragm by a suitable binder.
  • the suspension means provides an edge for the cone which has a curved portion with a nearly semicircular cross section projecting upward at its center, which is elastically deformable due to its own elasticity, whereby the diaphragm can be linearly vibrated in the vertical direction.
  • the stiffness of the edge has an important effect on the lower frequency characteristic. The stiffness should be reduced for the lowering of the lower threshold frequency.
  • the edge is generally formed of urethane sponge or cotton cloth impregnated with phenol resin, or of a mixture of nitryl butadiene rubber, styrene butadiene rubber or isobutyI-isoprene rubber with carbonic fine grains.
  • the edge be deformable both radially and peripherally.
  • the peripheral deformation be larger than the radial deformation.
  • An edge formed of cotton cloth has the following disadvantages. When the diaphragm is strongly vibrated, the edge is wrinkled and its internal loss is increased, since it is little deformed in the peripheral direction. Moreover, sounds are generated from the edge.
  • An edge formed of the vulcanized mixture of the above-mentioned rubber with carbonic fine grains has the following disadvantages:
  • the thickness of the edge should be relatively large for the required stiffness. Therefore, the sound conversion efficiency is lowered with the increase of the weight of the edge.
  • the damper is annular and undulated in shape, and deformable in a radial direction. This prevents the voice coil from contacting the yoke during vibration. It supports the diaphragm and the voice coil.
  • the stiffness of the damper has an important effect on the lower threshold frequency f
  • the damper is manufactured in such a manner that the cotton cloth impregnated with phenol resin is formed under heat into undulation so as to obtain a lower stiffness.
  • the conventional damper cannot be deformed in a peripheral direction when the vibration system is operated. Accordingly, the linearity of the deformabilityis unsatisfactory under large vibrations.
  • the size and the thickness of the damper are increased for the required stiffness and so the weight of the damper is increased. Accordingly, the internal loss of the damper is decreased. Therefore, the mechanical impedance of the loudspeaker is increased in the lower frequency range. As the result, the sharpnesses of the mechanical resonance and the electrical resonance are increased and so the quality of the reproduced sounds is worsened.
  • One object of this invention is to provide a loudspeaker with a good frequency response characteristic.
  • Another object of this invention is to provide a loudspeaker with a good sound characteristic in which the suspension means is improved for supporting the cone or the diaphragm.
  • Another object of this invention is to provide a loudspeaker with a light suspension means having a high degree of stiffness, in which a diaphragm is suspended by a suspension means formed of a mixture of elastic material with carbon fibers.
  • Another object of this invention is to provide a loudspeaker generating no radiate sound from a suspension means, in which a diaphragm is suspended by a suspension means containing short carbon fibers aligned radially, and inwhich the suspension means is prevented from wrinkling.
  • Another object of this invention is to provide a loudspeaker with a cone-type diaphragm in which the conetype diaphragm is suspended by an improved suspension means with a large internal loss at its lower end.
  • Another object of this invention is to provide a loudspeaker with a cone-type diaphragm in which the conetype diaphragm is suspended by an improved suspension means formed of a mixture of elastic material with carbon fibers and deformable in the peripheral direction, at its lower end,and therefore in which the sharpnesses of mechanical and electrical resonances are decreased.
  • a still further object of this invention is to provide a loudspeaker with a cone-type diaphragm in which the cone-type diaphragm is suspended by a suspension means containing carbon fibers at its upper end and lower end, whereby signals can be converted into sounds with high fidelity in a higher frequency range and vibration can be sufficiently damped in a lower fre- BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic cross-sectional view of a loudspeaker of one preferred embodiment of this invention
  • FIG. 2 is a plan view of a first suspension means in FIG. 1;
  • FIG. 3 is an enlarged plan view of a part of the first suspension means shown in FIG. 2',
  • FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3;
  • FIG. 5 is a cross-sectional view of a metal mold employed for the manufacture of the first suspension means shown on FIG. 2;
  • FIG. 6 is a plan view of a second suspension means in FIG. 1;
  • FIG. 7 is an enlarged plan view of a part of the second suspension means shown on FIG. 6;
  • FIG. 8 is a cross-sectional view taken along the line VIIIVIII of FIG. 7;
  • FIG. 9 is a graph showing a frequency-response characteristic
  • FIG. 10 is a graph showing a frequency-impedance characteristic.
  • the magnetic portion of a loudspeaker 1 comprises a circular yoke 2a, an annular yoke 21), an annular magnet 3 disposed between the circular yoke 12:: and the annular yoke 21;, and a central pole 4 which extends upwardly from the center of the circular yoke 2a and is fixed with respect thereto.
  • a vibration system comprises a bobbin 5 for a voice coil, a voice coil 6 wound around the bobbin 5 and a cone-shaped diaphragm 9 fixed on the upper end of the bobbin 5.
  • the first annular suspension means is bonded to the upper end of the frame 7 and to the upper end of the diaphragm 9, with a suitable binder.
  • a second annular suspension means, namely a damper 28 is bonded to the lower end of the diaphragm 9 to suspend the diaphragm 9 elastically from the frame 7.
  • a sound absorber 11 is fixed on the upper face of the bobbin 5.
  • a cap 12 covers the surface of the sound absorber 11.
  • a clamping ring 13 is fixed on the upper end of the edge 20 to prevent the edge 20 from peeling from the upper end of the frame 7.
  • the first suspension means 20 will now be described in detail with reference to FIGS. 2 to 4.
  • the first suspension means 20 defines a curved or ridge-like portion 20a with a nearly semicircular cross section projecting upward, an inclining portion 20b and an outer horizontal circumferential portion 200.
  • the first suspension means 20 is manufactured in such a manner that carbon fibers 21 with lengths of 0.3 to 0.8 mm are mixed into an elastic material such as synthetic rubber, (for example, nitryl butadiene rubber, styrene butadiene rubber and isobutyl-isoprene rubber), natural rubber or synthetic resin (for example, soft-foamedurethane).
  • the carbon fibers 21 are aligned radially as diagrammatically shown in FIG. 3.
  • the upper end of the diaphragm 9 is fixed on the inclined portion 20b of the first suspension means 20, and the upper end of the frame 7 is fixed to the horizontal circumferential portion 200 of the first suspension means 20.
  • a required temperature for example 150C, which defines an annular groove 24 having the same cross section as the first suspension means 20.
  • Another metal mold 26 is provided having a mating annular projection 25 of the same cross section as the annular groove 24.
  • the metal mold 26 is brought over the one metal mold 23, heated up to the said required temperature.
  • the mixture 22 is put between the metal molds 23 and 26. Accordingly, as the metal mold 26 is pressed down, the mixture 22 is radially spread out from the center of the metal mold 23 in the direction shown by the arrows 27 in FIG. 5 and then led into the annular groove 24, between the metal molds 23 and 26.
  • the mixture 22 is vulcanized at a temperature over C, between the metal molds 23 and 26. Thereafter, the metal molds 23 and 26 are cooled to solidify the mixture 22. The formed mixture 22 is drawn out from the metal mold 23. As the result, the first suspension means 20 is obtained, as shown on FIG. 2 and FIG. 4.
  • the carbon fibers 21 contained in the mixture 22 are displaced directionally. Therefore, the carbon fibers 21 with the lengths of 0.3 to 0.8 mm are radially dispersed in the direction of the diameter of the first suspension means 20 (FIG. 3).
  • the deformability of the first suspension means 20 is improved on the peripheral direction. There is no possibility that the first suspension means 20 will be wrinkled.
  • the specific weight of the first suspension means 20 is small and the stiffness of the first suspension means 20 is large, since it is manufactured in a vulcanizing process of the mixture containing carbon fibers. Consequently, the thickness of the curved portion 20a of the first suspension means 20 can be reduced to the minimum for the required stiffness and so the total weight of the first suspension means 20 can be reduced.
  • the second suspension means 28 is also formed of the mixture of elastic material with the carbon fibers.
  • a second suspension means 28 has a plurality of concentric curved portions 28a with a semicircular cross section projecting upward. It also has curved portions 28b with a semicircular cross section projecting downward, an inner edge portion 28c with a U-shaped cross section projecting downward, and a horizontal circumferential portion 28d.
  • the second suspension means 28 is formed of a mixture of the same elastic material as the first suspension means 20 with the carbon fibers. As shown in FIG. 7, carbon fibers 31 with lengths of 0.3 to 0.8 mm are radially aligned in the direction of the diameter of the second suspension means 28. It is preferable that the Youngs modulus of the carbon fiber be more than 20,000 kg/mm and that the diameter of the carbon fiber is smaller than the length of the carbon fiber, for
  • the inner end portion 280 is bonded to the bobbin 5 and the horizontal circumferential portion 28d is bonded to the frame 7.
  • the second suspension means 28 can be manufactured in the same manner as the first suspension means 20.
  • the deformability of the second suspension means 28 is higher in the peripheral direction than in the radial direction, since the carbon fibers 31 are radially dis-- persed in the second suspension means 28.
  • a mixture of styrene butadiene rubber with the carbon fibers is vulcanized for the manufacture of the second suspension means 28, a small specific weight ,and a large stiffness can be obtained for the second suspension means 28. Consequently, thethickness of the sec ond suspension means 28 can be reduced to a minimum for the required stiffness and hence the total'weight of the second suspension means 28 can be reduced.
  • FIG. 9 shows the frequency-response characteristics of cone-type dynamic speakers using the first suspension means according to this invention and the conventional first suspension means formed of cotton cloth.
  • FIG. 10 shows frequency-impedance characteristics.
  • Curve a is for a conventional loudspeaker using a damper formed of cotton cloth impregnated with phenol resin, where the resonant frequency f,, is 78 Hz, the maximum impedance Z 100 O. and the minimum impedance R 6 .Q.
  • the sharpness Q of the mechanical resonance is represented by an equation where f and f are frequencies for an impedance From the curve a,f 67 Hz andf 88 Hz are apparent. Therefore,
  • the frequency characteristic is remarkably improved by using the second suspension means 28 according to Therefore, the sharpness Q of the mechanical resonance is And the sharpness Q of the electrical resonance is It will be understood that Q and Q,, can be remarkably lowered by the second suspension means according to this invention, compared with the conventional suspension means.
  • a loudspeaker comprising a diaphragm with a voice coil, a frame surrounding said diaphragm, and a suspension means for suspending said diaphragm from said frame, said suspension means being formed of a mixture of elastic material impregnated with carbon fibers.
  • a loudspeaker according to claim 2 wherein said suspension means is disposed between the upper portion of said diaphragm and said frame and it defines an intermediate portion having an arcuate cross section.
  • a loudspeaker according to claim 2 wherein said suspension means is disposed between the lower portion of said diaphragm and said frame and it defines an intermediate portion having a wave-like cross section.
  • a loudspeaker comprising a coneshaped diaphragm with a voice coil, a frame surrounding said cone-shaped diaphragm, a first suspension means for suspending the upper part of said diaphragm from said frame, and a second suspension means for suspending the lower part of said diaphragm from said frame, at least one of said suspension means being formed of a mixture of elastic material impregnated with carbon fihers.
  • a loudspeaker according to claim 6, wherein said elastic material is rubber and said carbon fibers are needle-like and are radially aligned in said one of said first suspension means and said second suspension said first and said second suspension means.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
US483154A 1973-07-02 1974-06-26 Loudspeaker Expired - Lifetime US3905448A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1973078632U JPS5351154Y2 (en)) 1973-07-02 1973-07-02

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3980841A (en) * 1975-05-23 1976-09-14 K.K. Fujita Shoten Speaker edge
US4206832A (en) * 1979-01-17 1980-06-10 Yocum Thomas A Drone acoustical transducer
DE3325520A1 (de) * 1983-07-15 1985-01-31 Wolfgang 6000 Frankfurt Koppel Vorentzerrtes elektroakustisches wandlersystem
EP0477500A3 (en) * 1990-09-25 1993-01-20 Nokia (Deutschland) Gmbh Diaphragm for cone loudspeaker
EP0508150A3 (en) * 1991-04-11 1993-07-14 Nokia (Deutschland) Gmbh Loudspeaker with an element joining the suspension and the (built-in) seal
US5578800A (en) * 1994-02-28 1996-11-26 Nitto Denko Corporation Member for loudspeaker
US5682435A (en) * 1994-11-04 1997-10-28 U.S. Philips Corporation Apparatus comprising a baffle and a loudspeaker, and loudspeaker for use in the apparatus
US5847333A (en) * 1996-05-31 1998-12-08 U.S. Philips Corporation Electrodynamic loudspeaker and system comprising the loudspeaker
US5892184A (en) * 1996-05-31 1999-04-06 U.S. Philips Corporation Passive radiator and system comprising the passive radiator
US5933508A (en) * 1993-09-22 1999-08-03 Sony Corporation Horn speaker system
US6305491B2 (en) * 1998-05-08 2001-10-23 Matsushita Electric Industrial Co., Ltd. Speaker
US20020170773A1 (en) * 2001-03-27 2002-11-21 Harman International Industries, Incorporated Tangential stress reduction system in a loudspeaker suspension
US20020170774A1 (en) * 2001-04-19 2002-11-21 Pioneer Corporation Speaker parts and method of manufacturing same
US20030070869A1 (en) * 2001-10-16 2003-04-17 Hlibowicki Stefan R. Low distortion loudspeaker cone suspension
US20070102231A1 (en) * 2005-11-10 2007-05-10 Hiroshi Ohara Connecting sheet of paper cone
US20080181445A1 (en) * 2007-01-31 2008-07-31 Yon Shing Industrial Co., Ltd. Full-gamut single-body sound membrane that conforms to a physical property of sounding
US20100171380A1 (en) * 2007-08-07 2010-07-08 Spal Automotive S.R.L Electric machine
US20180338202A1 (en) * 2017-05-17 2018-11-22 Harman International Industries, Incorporated Complementary driver alignment
CN111918178A (zh) * 2020-07-29 2020-11-10 国光电器股份有限公司 一种扬声器用碳纤纸盆的制备方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5418912Y2 (en)) * 1973-12-28 1979-07-14
JPH03184Y2 (en)) * 1986-03-10 1991-01-08
JPH0247949Y2 (en)) * 1986-06-25 1990-12-17

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406126A (en) * 1966-12-07 1968-10-15 Avco Corp Conductive synthetic resin composition containing carbon filaments
US3706695A (en) * 1970-10-12 1972-12-19 Dow Corning Method of preparing a silicone emulsion and regenerating same and electrically conductive product
US3767004A (en) * 1971-03-19 1973-10-23 A Liebscher Loudspeakers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406126A (en) * 1966-12-07 1968-10-15 Avco Corp Conductive synthetic resin composition containing carbon filaments
US3706695A (en) * 1970-10-12 1972-12-19 Dow Corning Method of preparing a silicone emulsion and regenerating same and electrically conductive product
US3767004A (en) * 1971-03-19 1973-10-23 A Liebscher Loudspeakers

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3980841A (en) * 1975-05-23 1976-09-14 K.K. Fujita Shoten Speaker edge
US4206832A (en) * 1979-01-17 1980-06-10 Yocum Thomas A Drone acoustical transducer
DE3325520A1 (de) * 1983-07-15 1985-01-31 Wolfgang 6000 Frankfurt Koppel Vorentzerrtes elektroakustisches wandlersystem
EP0477500A3 (en) * 1990-09-25 1993-01-20 Nokia (Deutschland) Gmbh Diaphragm for cone loudspeaker
EP0508150A3 (en) * 1991-04-11 1993-07-14 Nokia (Deutschland) Gmbh Loudspeaker with an element joining the suspension and the (built-in) seal
US5933508A (en) * 1993-09-22 1999-08-03 Sony Corporation Horn speaker system
US5578800A (en) * 1994-02-28 1996-11-26 Nitto Denko Corporation Member for loudspeaker
EP0669784A3 (en) * 1994-02-28 2000-05-10 Nitto Denko Corporation Edge for loudspeaker
US5682435A (en) * 1994-11-04 1997-10-28 U.S. Philips Corporation Apparatus comprising a baffle and a loudspeaker, and loudspeaker for use in the apparatus
US5892184A (en) * 1996-05-31 1999-04-06 U.S. Philips Corporation Passive radiator and system comprising the passive radiator
US5847333A (en) * 1996-05-31 1998-12-08 U.S. Philips Corporation Electrodynamic loudspeaker and system comprising the loudspeaker
US6305491B2 (en) * 1998-05-08 2001-10-23 Matsushita Electric Industrial Co., Ltd. Speaker
US20050185817A1 (en) * 2001-03-27 2005-08-25 Brendon Stead Tangential stress reduction system in a loudspeaker suspension
US20020170773A1 (en) * 2001-03-27 2002-11-21 Harman International Industries, Incorporated Tangential stress reduction system in a loudspeaker suspension
US7438155B2 (en) * 2001-03-27 2008-10-21 Harman International Industries, Incorporated Tangential stress reduction system in a loudspeaker suspension
US20070272475A1 (en) * 2001-03-27 2007-11-29 Brendon Stead Tangential stress reduction system in a loudspeaker suspension
US7174990B2 (en) 2001-03-27 2007-02-13 Harman International Industries, Incorporated Tangential stress reduction system in a loudspeaker suspension
US6851513B2 (en) * 2001-03-27 2005-02-08 Harvard International Industries, Incorporated Tangential stress reduction system in a loudspeaker suspension
US6845169B2 (en) * 2001-04-19 2005-01-18 Pioneer Corporation Speaker parts and method of manufacturing same
US20020170774A1 (en) * 2001-04-19 2002-11-21 Pioneer Corporation Speaker parts and method of manufacturing same
US20030070869A1 (en) * 2001-10-16 2003-04-17 Hlibowicki Stefan R. Low distortion loudspeaker cone suspension
US6725967B2 (en) * 2001-10-16 2004-04-27 Audio Products International Corp. Low distortion loudspeaker cone suspension
US20070102231A1 (en) * 2005-11-10 2007-05-10 Hiroshi Ohara Connecting sheet of paper cone
US8243979B2 (en) * 2007-01-31 2012-08-14 Yon Shing Industrial Co., Ltd. Full-gamut single-body sound membrane that conforms to a physical property of sounding
US20080181445A1 (en) * 2007-01-31 2008-07-31 Yon Shing Industrial Co., Ltd. Full-gamut single-body sound membrane that conforms to a physical property of sounding
US20100171380A1 (en) * 2007-08-07 2010-07-08 Spal Automotive S.R.L Electric machine
US8362662B2 (en) * 2007-08-07 2013-01-29 Spal Automotive S.R.L. Electric machine having a heat dissipating construction
US8896168B2 (en) 2007-08-07 2014-11-25 Spal Automotive S.R.L. Electric machine having a heat dissipating construction
US20180338202A1 (en) * 2017-05-17 2018-11-22 Harman International Industries, Incorporated Complementary driver alignment
US10531181B2 (en) * 2017-05-17 2020-01-07 Harman International Industries, Incorporated Complementary driver alignment
CN111918178A (zh) * 2020-07-29 2020-11-10 国光电器股份有限公司 一种扬声器用碳纤纸盆的制备方法
CN111918178B (zh) * 2020-07-29 2021-12-10 国光电器股份有限公司 一种扬声器用碳纤纸盆的制备方法

Also Published As

Publication number Publication date
JPS5351154Y2 (en)) 1978-12-07
JPS5026826U (en)) 1975-03-27

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