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
  • H04R9/02—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; 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
• • 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
  • H04R9/025—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. 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.
• an electrodynamic transducer includes a magnet structure including a first inner, or core, pole and a second outer pole, or shell, defining an air gap between them.
• the air gap has a generally cylindrical configuration.
• the transducer further includes a diaphragm, a voice coil having a generally cylindrical configuration for displacement axially within the air gap, and means for coupling the voice coil to the diaphragm so that movement of the voice coil in response to current flow through the voice coil generates corresponding movement of the diaphragm. Openings are provided in the outer pole. The openings extend generally parallel with the axes of the air gap and voice coil.
• the means for coupling the voice coil to the diaphragm comprises ribs extending from the voice coil with a component radially of the axes of the air gap and voice coil. The ribs are secured to the diaphragm.
• 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.
• Fig. 1 illustrates an exploded fragmentary perspective view of an electrodynamic transducer constructed according to the present invention
• 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.
• 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 direction around sidewall 20 transverse to axis 26.
• 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.
• 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.

Landscapes

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

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23022723

Family Applications (1)

Country Status (8)

Cited By (4)

Citations (1)

Family Cites Families (3)

• 1989
  • 1989-09-25 CA CA000613041A patent/CA1318965C/en not_active Expired - Fee Related
  • 1989-10-12 DE DE68914164T patent/DE68914164T2/de not_active Expired - Fee Related
  • 1989-10-12 AU AU46268/89A patent/AU620185B2/en not_active Ceased
  • 1989-10-12 WO PCT/US1989/004501 patent/WO1990005435A1/en active IP Right Grant
  • 1989-10-12 EP EP89912920A patent/EP0441881B1/de not_active Expired - Lifetime
  • 1989-10-12 JP JP2500312A patent/JP2756037B2/ja not_active Expired - Lifetime
  • 1989-11-07 MX MX1825889A patent/MX170535B/es unknown
• 1991
  • 1991-05-01 DK DK91813A patent/DK81391D0/da not_active Application Discontinuation

Patent Citations (1)

Non-Patent Citations (1)

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