Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R11/00—Transducers of moving-armature or moving-core type
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2205/00—Details of stereophonic arrangements covered by H04R5/00 but not provided for in any of its subgroups
  • H04R2205/041—Adaptation of stereophonic signal reproduction for the hearing impaired
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2400/00—Loudspeakers
  • H04R2400/01—Transducers used as a loudspeaker to generate sound aswell as a microphone to detect sound

Definitions

• This patent generally relates to transducers useful in listening devices, such as hearing aids or the like, and more particularly, to a magnetic assembly for use in a transducer.
• BTE Behind-The-Ear
• ITE In-The-Ear
• ITC In-The-Canal
• CTC Completely-In-The-Canal
• a listening device such as a hearing aid or the like, includes a microphone assembly, an amplifier and a receiver (speaker) assembly.
• the microphone assembly receives acoustic sound waves, and generates an electronic signal representative of these sound waves.
• the amplifier accepts the electronic signal, modifies the electronic signal, and communicates the modified electronic signal (e.g. processed signal) to the receiver assembly.
• the receiver assembly converts the increased electronic signal into acoustic energy for transmission to a user.
• a known receiver assembly comprises a housing, an armature, a drive rod, a pair of drive magnets, a diaphragm, a drive coil, a yoke, a sound outlet port, and an electrical terminal.
• the diaphragm is disposed within the housing, defining an output chamber and a motor chamber.
• the armature is disposed within the motor chamber and has an operative element comprising a fixed end and a movable end.
• the armature is coupled by the drive rod to drive the diaphragm.
• the drive magnet structure having a central passage surrounds the movable end of the armature and provides a permanent magnetic field within the passage.
• the drive coil is disposed about the armature and is located proximate to the permanent magnet structure.
• the drive magnet may be disposed within the magnetic yoke.
• the drive magnet may be made of a hard magnetic material, such as, for example, Ferrite, Alnico.
• the magnetic yoke may be made of Nickel-Iron.
• This arrangement of the magnet assembly (drive magnet-magnetic yoke structure) has several disadvantages.
• the hard magnetic material used in the drive magnet often has a relatively low energy content and further it requires a certain thickness to provide sufficient flux density.
• the overall size of the magnetic yoke must be made large enough to avoid magnetic saturation.
• the physical volume of the material places limits on the size of the receiver assembly making size reductions difficult. [0006] Accordingly, there is a need for a transducer, for example a microphone or receiver that is inexpensive, simple to manufacture and scalable to relatively small sizes.
• Fig. 1 is a cross-sectional view of a transducer according to a described embodiment of the invention ⁇
• Fig. 2 is a cross-sectional view of a transducer according to a described embodiment of the invention; and
• Fig. 3 is a cross-sectional view of a transducer according to a described embodiment of the invention.
• FIGs. 1-2 illustrate a cross-sectional view of a transducer 100.
• the transducer 100 may be adapted as either a microphone, receiver or other such device, and may be useful in such devices as hearing aids, in-ear monitors, headphones, electronic hearing protection devices, and very small scale acoustic speakers.
• the transducer 100 includes a housing 102 having at least one sound outlet port 104.
• the housing 102 may be rectangular in cross-section, with a planar top 106, a bottom 108, and side walls 110, 112. In alternate embodiments, the housing 102 can be manufactured in a variety of configurations, such as, a cylindrical shape, a D-shape, a trapezoid shape, a roughly square shape, or any other desired geometry. In addition, the scale and size of the housing 102 may vary based on the intended application, operating conditions, required components, etc.
• An optional electrical terminal 114 may be affixed to the side wall 112 of the housing 102 by bonding or any other suitable method of attachment.
• the transducer 100 may further include operatively coupled a diaphragm 116, a magnet assembly 118, and a motor assembly 124.
• the magnet assembly 118 includes a pair of drive magnets 120 to provide sufficient electromagnetic flux density fixedly attached to a magnetic yoke 122.
• the magnet assembly 118 may generally be shaped to correspond to the shape and configuration of the housing 102 but may be formed to compliment the various shape and sizes of the different embodiments.
• the magnetic yoke 122 forms a rectangular frame having a central tunnel or channel defining an enclosure into which the drive magnets 120 mount and form an air gap 140 to carry the electromagnetic flux of the drive magnets 120 and the drive coil 130.
• the motor assembly 124 includes an armature 126, a link or drive rod 128, a drive coil 130, and a lead 132. The drive coil 130 and the electrical terminal 114 are both operably attached to the lead 132.
• the link or drive rod 128 may be a linkage assembly or a plurality of linkage assemblies.
• One of skill in the art will appreciate the principles and advantages of the embodiments described herein may be useful with all types of receivers, such as those with U-shaped or E- shaped armatures.
• the diaphragm 116 and the armature 126 are both operably attached to the drive rod 128.
• the armature 126 may be affixed to the diaphragm 116 by any other suitable method of attachment without utilizing the drive rod 128.
• more than one diaphragm may be used to increase the radiating area and increase the output of or sensitivity to acoustical signals of the transducer 100.
• the diaphragm 116 is shown to have at least one layer. However, the diaphragm 116 may utilize multiple layers.
• the armature 126 includes a fixed end 126a and a movable end 126b.
• the movable end 126b of the armature 126 extends along the drive coil 130 and the magnet assembly 118, which in turn connects to the diaphragm 116 with the drive rod 128.
• the fixed end 126a of the armature 126 extends on the outer side along the drive coil 130 and within the housing 102. As shown in FIG. 1, the fixed end 126a of the armature 126 is affixed to the housing by bonding or any other suitable method of attachment.
• FIG. 3 further illustrates the magnet assembly 118 and the construction of the transducer 100.
• the magnet assembly 118 includes a pair of drive magnets 120 fixedly attached to a magnetic yoke 122.
• the magnet assembly 118 exhibits high magnetic flux density in a small size owing to the high saturation inductance, high permeability and low coercivity material for the magnetic yoke 122 and a high energy product and high coercivity material for the drive magnets 120.
• the magnetic yoke 122 may be made of soft magnetic material having a high permeability and a high saturation inductance.
• the magnetic yoke 122 may be an Iron-Cobalt Vanadium (FeCoV) alloy, commonly available under the trade designation Permendur Hiperco 50A from Carpenter Technology Corporation, or of any similar materials.
• the material forming the magnetic yoke 122 should have a saturation inductance tesla (T) greater than 1.5 and preferably at least 2.0; a maximum permeability greater than about 10,000 and preferably greater than about 75,000; and a coercivity ampere per meter (A/m) less than 140.
• the drive magnets 120 may be made of a rare earth magnetic material having improved magnetic properties, improved intrinsic coercive forces, and improved maximum energy products.
• the drive magnets 120 may be a Samarium-Cobalt (SmCo 5 , Sm 2 Co 17 ) alloy, a Neodymium-Iron-Boron (NdFeB) alloy, or of any similar materials.
• the drive magnets In an embodiment using Samarium-Cobalt alloy, the drive magnets have a high magnetic flux density which thereby allows a reduction in the overall thickness of the transducer 100.
• the material forming the drive magnets 120 should have an energy product kilo-joules per cubic meter (kJ/m 3 ) greater than about 72, and preferably about 191 to about 422; saturation inductance telsa (T) greater than 1 and preferably about 1-1.5 and a coercivity (h c s, kA/m) greater than 140 and preferably about 690 to about 1040.
• kJ/m 3 energy product kilo-joules per cubic meter
• T saturation inductance telsa
• h c s, kA/m coercivity
• a current representing an input audio signal from the electrical terminal 114 is applied to the drive coil 130, a corresponding alternating current (a.c.) magnetic flux (not depicted) is produced from the drive coil 130 through the armature 126, drive magnets 120, and the magnetic yoke 122. Further, a corresponding direct current (d.c.) magnetic flux path 200 is produced from a first side of the magnet assembly 118, e.g., an upper member of the drive magnet 120 to the upper member of magnetic yoke 122 as shown in Fig.
• a second side of the magnet assembly 118 e.g., a lower member of magnetic yoke 122 to a lower member of the drive magnet 120 and across the air gap 140 as shown in Fig. 3.
• the movable end 126b of the armature 126 vibrates in response to the electromagnetic forces generated by the magnetic flux 200 produced by the magnet assembly 118 and the drive coil 130, which in turn, leads to the movement of the drive rod 128.
• the diaphragm assembly 116 moves in response to the vertical motion of the armature movable end 126b driven by the drive coil 130.
• the transducer 100 utilizes the corresponding motion of the armature movable end 126b and the diaphragm assembly 116 to generate output acoustical signal towards the user's eardrum. Doing so provides the advantages of reduced overall size of the receiver assembly while maintaining high efficiency.
• AU references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

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

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• 2004
  • 2004-06-14 CN CNA2004800433303A patent/CN1969590A/zh active Pending
  • 2004-06-14 WO PCT/US2004/018570 patent/WO2006001792A1/en active Application Filing
  • 2004-06-14 EP EP04754977A patent/EP1757162A1/de not_active Withdrawn

Patent Citations (1)

Non-Patent Citations (1)

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