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EP-4018683-B1 - HIGHLY COMPLIANT ELECTRO-ACOUSTIC MINIATURE TRANSDUCER

EP4018683B1EP 4018683 B1EP4018683 B1EP 4018683B1EP-4018683-B1

Inventors

  • CHENG, LEI
  • MUNRO, Andrew, D.
  • HAYNER, MARK, A.

Dates

Publication Date
20260506
Application Date
20200821

Claims (13)

  1. An electro-acoustic driver (100), comprising: a diaphragm (102) having a surface area configured to radiate acoustic energy; a suspension (106a) coupled to the diaphragm; and a support structure (104) coupled to the suspension (106a) and having an outer linear dimension in a plane of the support structure of approximately 6.0 millimeters, mm, or less, wherein the surface area of the diaphragm (102) is at least 49% of an overall cross-sectional area of the electro-acoustic driver in the plane of the support structure (104), characterised in that the suspension is non-planar in a resting position.
  2. The electro-acoustic driver of claim 1, wherein the suspension provides a stiffness of approximately 20 Newton/meter, N/m, or less.
  3. The electro-acoustic driver of claim 2, wherein the suspension provides a stiffness of approximately 10 N/m or less, or approximately 8 N/m or less.
  4. The electro-acoustic driver of claim 1, wherein the support structure is circular, and wherein the outer linear dimension comprises a diameter of the support structure as measured in a direction perpendicular to an axis of motion of diaphragm while radiating acoustic energy.
  5. The electro-acoustic driver of claim 1, wherein the suspension has an approximately half-rolled shape in the resting position.
  6. The electro-acoustic driver of claim 1, wherein the outer linear dimension of the support structure is equal to or less than approximately 5.2 mm, approximately 4.2 mm, approximately 4.0 mm, or approximately 3.0 mm.
  7. The electro-acoustic driver of claim 1, wherein the suspension comprises an elastomer.
  8. The electro-acoustic driver of claim 7, wherein the elastomer is molded.
  9. The electro-acoustic driver of claim 7, wherein the surface area of the diaphragm has a portion that is not covered by the elastomer.
  10. The electro-acoustic driver of claim 1, wherein the suspension provides a stiffness of approximately 25 N/m or less, and wherein the surface area is from approximately 7 square millimeters, mm 2 , to approximately 40 mm 2 .
  11. The electro-acoustic driver of claim 1, wherein the driver defines an acoustic volume of approximately 45-90 cubic millimeters, mm 3 , and wherein the stiffness of the suspension is maintained at or below approximately 25 N/m while the electro-acoustic driver radiates acoustic energy at up to approximately 130 decibels of sound pressure level, dBSPL, to approximately 145 dBSPL.
  12. The electro-acoustic driver of claim 1, wherein the surface area is less than approximately 40 mm 2 .
  13. The electro-acoustic driver of claim 1, wherein a ratio of the surface area to the stiffness of the suspension is 360 mm 3 /N or greater.

Description

TECHNICAL FIELD This disclosure generally relates to loudspeakers. More particularly, the disclosure relates to miniature transducers with a compliant suspension or surround. BACKGROUND Modern in-ear headphones, or earbuds, typically include microspeakers. The microspeaker may include a coil wound on a bobbin that is attached to an acoustic diaphragm. Motion of the diaphragm due to an electrical signal provided to the coil results in generation of an acoustic signal that is responsive to the electrical signal. The microspeaker may include a frame and/or housing, such as a sleeve or tube, which encloses the bobbin and coil. The microspeaker may also include a magnetic structure. As the size of the earbud decreases, it becomes increasingly difficult to fabricate the acoustic diaphragm and surrounding suspension in a manner that allows broad spectrum coverage. US 2017/359655 discloses a prior art electro-acoustic driver including a diaphragm formed of a compliant material, a bobbin configured to hold a winding of an electrical conductor and a housing having a housing axis that is substantially coaxial with the bobbin. The diaphragm is fixed to one end of the housing and has a substantially planar shape when the diaphragm is at rest. SUMMARY The present invention relates to an electro-acoustic driver according to claim 1. Advantageous embodiments are set forth in the dependent claims. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects and benefits will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic depiction of an example miniature transducer according to various implementations.FIG. 2 is a schematic diagram of example sub-components of a miniature transducer according to various implementations.FIG. 3 is a schematic depiction of an example miniature transducer according to various additional implementations.FIGS. 4A-4C are schematic diagrams illustrating example sub-components in a miniature transducer according to various further implementations.FIG. 5 is a schematic cross-sectional view of a miniature transducer according to various additional implementations.FIG. 6 is a close-up cross-sectional view of the miniature transducer in FIG. 5.FIG. 7 is a graph illustrating performance metrics for miniature transducers. It is noted that the drawings of the various implementations are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the implementations. In the drawings, like numbering represents like elements between the drawings. DETAILED DESCRIPTION This disclosure is based, at least in part, on the realization that a highly compliant surround or suspension can improve the performance of a microspeaker. Commonly labeled components in the FIGURES are considered to be substantially equivalent components for the purposes of illustration, and redundant discussion of those components is omitted for clarity. Numerical ranges and values described according to various implementations are merely examples of such ranges and values, and are not intended to be limiting of those implementations. In some cases, the term "approximately" is used to modify values, and in these cases, can refer to that value +/- a margin of error, such as a measurement error, which may range from 1 percent up to 5 percent in terms of dimensional tolerance in some cases. In contrast to conventional microspeakers, the microspeakers disclosed according to various implementations include a highly compliant (i.e., low stiffness) surround or suspension. At least one benefit of such high-compliance transducers is their broader spectral output when compared with conventional microspeakers, e.g., a higher acoustic displacement and output power across a larger range of frequencies, enabling output at lower frequencies. This disclosure is related to U.S. Patent Application Serial No. 15/182,014 filed on June 14, 2016, now U.S. Patent No. 9,986,355, titled ASSEMBLY AID FOR MINIATURE TRANSDUCER, and to U.S. Patent Application Serial No. 15/182,055 also filed on June 14, 2016, now U.S. Patent No. 9,942,662, titled ELECTRO-ACOUSTIC DRIVER HAVING COMPLIANT DIAPHRAGM WITH STIFFENING ELEMENT, and to U.S. Patent Application Serial No. 15/182,069, also filed on June 14, 2016, titled MINIATURE DEVICE HAVING AN ACOUSTIC DIAPHRAGM, and to U.S. Patent Application Serial No. 15/222,539 filed on July 28, 2016, titled FABRICATING AN INTEGRATED LOUDSPEAKER PISTON AND SUSPENSION. Acoustic transducers structurally similar to those described in the above referenced patent applications and/or the disclosure herein, and/or assembled in accord with methods similar to those described in the above referenced patent applications or those described herein, may meet dimensional criteria and compliance and/or st