EP0441881B1 - Shallow loudspeaker with slotted magnet structure - Google Patents

Shallow loudspeaker with slotted magnet structure Download PDF

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Publication number
EP0441881B1
EP0441881B1 EP89912920A EP89912920A EP0441881B1 EP 0441881 B1 EP0441881 B1 EP 0441881B1 EP 89912920 A EP89912920 A EP 89912920A EP 89912920 A EP89912920 A EP 89912920A EP 0441881 B1 EP0441881 B1 EP 0441881B1
Authority
EP
European Patent Office
Prior art keywords
voice coil
air gap
diaphragm
ribs
axes
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
EP89912920A
Other languages
German (de)
French (fr)
Other versions
EP0441881A1 (en
EP0441881A4 (en
Inventor
William Neal House
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Harman International Industries Inc
Original Assignee
Harman International Industries Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=23022723&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0441881(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Harman International Industries Inc filed Critical Harman International Industries Inc
Publication of EP0441881A1 publication Critical patent/EP0441881A1/en
Publication of EP0441881A4 publication Critical patent/EP0441881A4/en
Application granted granted Critical
Publication of EP0441881B1 publication Critical patent/EP0441881B1/en
Anticipated expiration legal-status Critical
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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
    • H04R9/045—Mounting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit

Definitions

  • This invention relates to electrodynamic transducers and more specifically to a novel configuration of the magnet structure and diaphragm which permits a shallower transducer to be realized than is permitted by prior art designs.
  • the listed prior art generally illustrates what are believed to be the shallowest transducer designs available with existing technology, the illustrated designs suffer from the weakness that the transducer must be designed with space between the diaphragm and magnet assembly when the voice coil is unexcited so that no collisions occur between the diaphragm and magnet assembly when the voice coil is excited.
  • a transducer whose design is intended to provide a .6 inch (1.5 cm) peak to peak excursion, a space of at least .3 inch (.75 cm) must be provided between the diaphragm and adjacent surfaces of the magnet assembly when the voice coil is unexcited.
  • collisions between the diaphragm and magnet assembly must be avoided to prevent the audible distortion which accompanies such collisions.
  • JP-A-60/68799 discloses a loudspeaker structure with two poles defining between them an air gap, and a voice coil connected to the diaphragm. This has been taken as the basis for the preamble of claim 1.
  • the first pole is an inner, or core
  • the second pole is an outer pole, or shell.
  • the air gap has a generally cylindrical configuration.
  • the voice coil has a generally cylindrical configuration for displacement axially within the air gap.
  • the openings are provided in the outer pole.
  • the diaphragm comprises an opening having an inner sidewall, and the ribs are secured at their radially outer extents to the inner sidewall, the diaphragm is generally planar, and the inner sidewall is right circular cylindrical.
  • the air gap and voice coil are generally right circular cylindrical in configuration.
  • the openings in the outer pole are generally slot-shaped.
  • the openings are elongated in the direction of the air gap and voice coil axes and narrow in a direction transverse to the air gap and voice coil axes.
  • the ribs are elongated in the direction of the air gap and voice coil axes and narrow in a direction transverse to the air gap and voice coil axes.
  • the means for coupling the voice coil to the diaphragm further comprises a voice coil form for supporting the voice coil in the air gap.
  • the ribs are secured at their radially inner extents to the voice coil form.
  • the transducer includes a back plate 10 which can be constructed from any suitable material such as a metal or filled or unfilled resin.
  • Back plate 10 extends outward from the transducer components illustrated in the figures and typically supports the outer perimeter (not shown) of the diaphragm 12 of the transducer by some suitable configuration which is not the subject of this invention.
  • An outer pole, or shell, 14 is mounted, such as by a suitable adhesive, on back plate 10.
  • Shell 14 is constructed from a material which has a high magnetic permeability, a ferromagnetic material. Shell 14 defines within it a generally right circular cylindrical space 17, open at the top 16. Slots 18 extend along the length of the sidewall 20 of shell 14 from its floor 22 to its upper lip 24. Slots 18 are elongated in the direction of the axis 26 of the right circular cylindrical space and narrow in the circumferential direction.
  • a right circular cylindrical ferromagnet 28 and a high magnetic permeability, right circular cylindrical slug 30 are stacked on the floor 22 of shell 14 to form the inner, or core, pole 31 of a yoke 32 with shell 14.
  • a right circular cylindrical air gap 34 coaxial with space 17 and core pole 31 is thus formed.
  • Diaphragm 12 includes an inner circular opening 36 defined by a right circular cylindrical wall 38 having a radius larger than the radius of shell 14 so that diaphragm 12 will slide down around the shell 14.
  • Several ribs 40 extend radially inward from wall 38 and join the outer sidewall of a right circular cylindrical voice coil form 42.
  • the dimensions of ribs 40 and voice coil form 42 are such that the ribs 40 move freely without contact in slots 18 and voice coil form 42 and the voice coil 44 which is provided on the radially inner surface 46 thereof move freely without contact in air gap 34.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Toys (AREA)

Abstract

An electrodynamic transducer includes a magnet structure (14, 28, 30) having inner (31) and outer (14) poles defining between them an air gap (17), a diaphragm (12), and a voice coil (44). Openings (18) are provided in the outer pole (14), the openings (18) extending generally parallel with the air gap (17) and the direction of motion of the voice coil (44) in the air gap (17). The voice coil (44) is coupled to the diaphragm (12) by ribs (40) extending transversely across the air gap (17) and through the openings (18) for securing the voice coil (44) to the diaphragm (12).

Description

  • This invention relates to electrodynamic transducers and more specifically to a novel configuration of the magnet structure and diaphragm which permits a shallower transducer to be realized than is permitted by prior art designs.
  • Various shallow and flat diaphragm designs are known. There are, for example, the designs illustrated by the following U.S. Patents: 1,766,612; 2,498,825; 2,858,377; 3,153,463; 4,379,951; 4,385,210; 4,508,941; and, 4,520,237. This listing is only intended as illustrative of the prior art and specifically is not intended as a representation that no closer prior art exists to the claimed invention. Although the listed prior art generally illustrates what are believed to be the shallowest transducer designs available with existing technology, the illustrated designs suffer from the weakness that the transducer must be designed with space between the diaphragm and magnet assembly when the voice coil is unexcited so that no collisions occur between the diaphragm and magnet assembly when the voice coil is excited. For example, in a transducer whose design is intended to provide a .6 inch (1.5 cm) peak to peak excursion, a space of at least .3 inch (.75 cm) must be provided between the diaphragm and adjacent surfaces of the magnet assembly when the voice coil is unexcited. Of course, collisions between the diaphragm and magnet assembly must be avoided to prevent the audible distortion which accompanies such collisions.
  • It is an object of the present invention to provide an electrodynamic transducer structure in which it is not necessary to provide space between the diaphragm and magnet structure in the direction in which excursion of the diaphragm occurs.
  • JP-A-60/68799 discloses a loudspeaker structure with two poles defining between them an air gap, and a voice coil connected to the diaphragm. This has been taken as the basis for the preamble of claim 1.
  • The essential features of the invention are set out in claim 1.
  • In a preferred embodiment of the invention,the first pole is an inner, or core, pole and the second pole is an outer pole, or shell. The air gap has a generally cylindrical configuration. The voice coil has a generally cylindrical configuration for displacement axially within the air gap. The openings are provided in the outer pole.
  • Illustratively, the diaphragm comprises an opening having an inner sidewall, and the ribs are secured at their radially outer extents to the inner sidewall, the diaphragm is generally planar, and the inner sidewall is right circular cylindrical.
  • Further, illustratively, the air gap and voice coil are generally right circular cylindrical in configuration.
  • According to the illustrative embodiment, the openings in the outer pole are generally slot-shaped.
    The openings are elongated in the direction of the air gap and voice coil axes and narrow in a direction transverse to the air gap and voice coil axes. Also according to the illustrative embodiment, the ribs are elongated in the direction of the air gap and voice coil axes and narrow in a direction transverse to the air gap and voice coil axes.
  • According to the illustrative embodiment, the means for coupling the voice coil to the diaphragm further comprises a voice coil form for supporting the voice coil in the air gap. The ribs are secured at their radially inner extents to the voice coil form.
  • The invention may best be understood by referring to the following description and accompanying drawings which illustrate the invention. In the drawings:
    • Fig. 1 illustrates an exploded fragmentary perspective view of an electrodynamic transducer constructed according to the present invention; and
    • Fig. 2 illustrates a fragmentary sectional side elevational view of the electrodynamic transducer of Fig. 1, taken generally along section lines 2-2 of Fig. 1.
  • Referring to both figures, the transducer includes a back plate 10 which can be constructed from any suitable material such as a metal or filled or unfilled resin. Back plate 10 extends outward from the transducer components illustrated in the figures and typically supports the outer perimeter (not shown) of the diaphragm 12 of the transducer by some suitable configuration which is not the subject of this invention. An outer pole, or shell, 14 is mounted, such as by a suitable adhesive, on back plate 10. Shell 14 is constructed from a material which has a high magnetic permeability, a ferromagnetic material. Shell 14 defines within it a generally right circular cylindrical space 17, open at the top 16. Slots 18 extend along the length of the sidewall 20 of shell 14 from its floor 22 to its upper lip 24. Slots 18 are elongated in the direction of the axis 26 of the right circular cylindrical space and narrow in the circumferential direction.
  • A right circular cylindrical ferromagnet 28 and a high magnetic permeability, right circular cylindrical slug 30 are stacked on the floor 22 of shell 14 to form the inner, or core, pole 31 of a yoke 32 with shell 14. A right circular cylindrical air gap 34 coaxial with space 17 and core pole 31 is thus formed.
  • Diaphragm 12 includes an inner circular opening 36 defined by a right circular cylindrical wall 38 having a radius larger than the radius of shell 14 so that diaphragm 12 will slide down around the shell 14. Several ribs 40 extend radially inward from wall 38 and join the outer sidewall of a right circular cylindrical voice coil form 42. The dimensions of ribs 40 and voice coil form 42 are such that the ribs 40 move freely without contact in slots 18 and voice coil form 42 and the voice coil 44 which is provided on the radially inner surface 46 thereof move freely without contact in air gap 34.
  • It will be appreciated with reference to Fig. 2 that the entire excursion of diaphragm 12 between its peak limits T and B is below the level of lip 24 of shell 14. Thus, the object is achieved of providing a transducer structure wherein space between the diaphragm 12 and magnet structure 14, 28, 30 in the direction in which excursion of the diaphragm 12 occurs is eliminated.

Claims (10)

  1. An electrodynamic transducer comprising a magnet structure (32) including first and second poles (14,30) defining between themselves an air gap (34), a diaphragm (12), a voice coil (44), and means (40) for coupling the voice coil (44) to the diaphragm (12), characterized in that openings (18) are provided in at least one of the poles, the openings (18) extending substantially parallel with the air gap (34) and the direction of motion of the voice coil (44) in the air gap, and wherein the means (40) for coupling the voice coil (44) to the diaphragm (12) comprises ribs (40) extending transversely across the air gap and securing the voice coil to the diaphragm.
  2. The apparatus of claim 1 wherein the first and second poles comprise an inner pole (30) and an outer pole (14), respectively, the voice coil (44) having a substantially cylindrical configuration, and the air gap (34) having a substantially cylindrical configuration, the ribs (40) extending substantially radially of the axes of the voice coil (44) and air gap between the voice coil and diaphragm (12).
  3. The apparatus of claim 2 wherein the openings are in the outer pole (14) and are in the shape of slots (18) which are elongated in the direction of the air gap and voice coil axes and narrow in a direction transverse to the air gap and voice coil axes.
  4. The apparatus of claim 3 wherein the ribs (40) are elongated in the direction of the air gap (34) and voice coil (44) axes and narrow in a direction transverse to the air gap and voice coil axes.
  5. The apparatus of any one of claims 2 to 4 wherein the means for coupling the voice coil (44) to the diaphragm (12) further comprises a voice coil form (42) for supporting the voice coil in the air gap, the ribs being secured at their radially inner ends to the voice coil form.
  6. The apparatus of any one of claims 2 to 5, wherein the air gap (34) and voice coil (44) are substantially right circular cylindrical.
  7. The apparatus of any one of claims 2 to 6 wherein the diaphragm (12) comprises an opening having an inner sidewall (38) and the ribs (40) are secured at their radially outer ends to the inner sidewall.
  8. The apparatus of claim 7, wherein the inner sidewall (38) of the opening in the diaphragm (12) is substantially cylindrical.
  9. The apparatus of claim 8, wherein the inner sidewall (38) of the opening in the diaphragm (12) is substantially right circular cylindrical.
  10. The apparatus of any one of claims 1 to 9, wherein the diaphragm (12) is substantially planar.
EP89912920A 1988-11-07 1989-10-12 Shallow loudspeaker with slotted magnet structure Expired - Lifetime EP0441881B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US26837688A 1988-11-07 1988-11-07
US268376 1988-11-07

Publications (3)

Publication Number Publication Date
EP0441881A1 EP0441881A1 (en) 1991-08-21
EP0441881A4 EP0441881A4 (en) 1991-09-04
EP0441881B1 true EP0441881B1 (en) 1994-03-23

Family

ID=23022723

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89912920A Expired - Lifetime EP0441881B1 (en) 1988-11-07 1989-10-12 Shallow loudspeaker with slotted magnet structure

Country Status (8)

Country Link
EP (1) EP0441881B1 (en)
JP (1) JP2756037B2 (en)
AU (1) AU620185B2 (en)
CA (1) CA1318965C (en)
DE (1) DE68914164T2 (en)
DK (1) DK81391D0 (en)
MX (1) MX170535B (en)
WO (1) WO1990005435A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9210463U1 (en) * 1992-08-05 1992-10-22 Nokia (Deutschland) GmbH, 7530 Pforzheim Coaxial speaker arrangement
ATE388601T1 (en) * 2000-01-27 2008-03-15 Nxp Bv ELECTROACOUSTIC TRANSDUCER HAVING A MEMBRANE WITH COIL MOUNTING PROJECTIONS AND INTERMEDIATE STABILIZING WALLS
EP1229759B1 (en) 2000-09-04 2008-10-15 Matsushita Electric Industrial Co., Ltd. Speaker
WO2012038981A1 (en) * 2010-09-23 2012-03-29 Praveen Vallabhaneni Linear actuation loudspeaker driver

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281223A (en) * 1978-08-18 1981-07-28 Sony Corporation Electro-acoustic transducer

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5627600A (en) * 1979-08-10 1981-03-17 Kanenori Kishi Magnetic circuit of moving coil type transducer
AU595703B2 (en) * 1987-04-08 1990-04-05 Harman International Industries Incorporated Shallow loudspeaker

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281223A (en) * 1978-08-18 1981-07-28 Sony Corporation Electro-acoustic transducer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Abstract of & JP-A-60-068799 *

Also Published As

Publication number Publication date
JPH04501643A (en) 1992-03-19
JP2756037B2 (en) 1998-05-25
DE68914164D1 (en) 1994-04-28
CA1318965C (en) 1993-06-08
WO1990005435A1 (en) 1990-05-17
EP0441881A1 (en) 1991-08-21
MX170535B (en) 1993-08-30
DK81391A (en) 1991-05-01
AU620185B2 (en) 1992-02-13
EP0441881A4 (en) 1991-09-04
DK81391D0 (en) 1991-05-01
AU4626889A (en) 1990-05-28
DE68914164T2 (en) 1994-06-30

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