WO1995021512A1 - Microphone pouvant etre utilise sous l'eau - Google Patents

Microphone pouvant etre utilise sous l'eau Download PDF

Info

Publication number
WO1995021512A1
WO1995021512A1 PCT/US1995/001301 US9501301W WO9521512A1 WO 1995021512 A1 WO1995021512 A1 WO 1995021512A1 US 9501301 W US9501301 W US 9501301W WO 9521512 A1 WO9521512 A1 WO 9521512A1
Authority
WO
WIPO (PCT)
Prior art keywords
microphone
housing
transducer
hydrophobic membrane
volume
Prior art date
Application number
PCT/US1995/001301
Other languages
English (en)
Inventor
Timothy K. Wickstrom
Original Assignee
Knowles Electronics, 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
Application filed by Knowles Electronics, Inc. filed Critical Knowles Electronics, Inc.
Priority to AU17386/95A priority Critical patent/AU1738695A/en
Publication of WO1995021512A1 publication Critical patent/WO1995021512A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/44—Special adaptations for subaqueous use, e.g. for hydrophone

Definitions

  • the invention relates to microphones, such as electret microphones, and more particularly to a water-submersible microphone which is capable of use at varying atmospheric pressures.
  • Conventional electret microphones typically include a housing supporting a microphone trans ⁇ ducer, wherein the microphone transducer comp ⁇ rises a diaphragm and a charged backplate.
  • the microphone transducer converts sound energy to a corresponding electrical signal.
  • the microphone transducer defines a front volume and a back volume within the housing.
  • a first sound entry port is provided in the housing to permit sound pressure to enter the front volume and vibrate the diaphragm.
  • a second sound entry port is also provided in the housing to permit sound pressure to enter the back volume and vibrate the dia- phragm, to thereby cancel certain of the sound entering through the first sound entry port.
  • electronics such as an amplifier, are often contained in the back volume. Because of the sensitivity of the charged plate and the microphone electronics, the back volume must be closed to environmental contaminants, such as moisture and dirt. In non-directional micro ⁇ phones, this is accomplished relatively easily because the back volume is closed to the environ ⁇ ment.
  • a barometric relief vent is necessary to permit equalization of pressure on opposing sides of the microphone transducer.
  • This barometric relief vent has conventionally been in the form of a hole through the microphone transducer to permit air to enter and leave the back volume as necessary to maintain equalized pressure.
  • the microphone be water-submersible, such as, for example, use in aircraft headsets wherein there is a chance that the aircraft personnel might have to bail out into the water, and one wants the headset operational as soon as the personnel surfaces.
  • Other instances include use in conjunction with dive headsets.
  • the relief vent in order to permit the microphone to withstand submersion in water, the relief vent must not permit water to pass through and enter the back volume, as such water would effectively never drain from the back volume, and the water in the back volume ultimately would damage the charged plate and microphone electronics.
  • a semi-pervious membrane such as GORE-TEX or TETRATEX.
  • the semi-pervious membrane permits only air to pass through the relief vent, and not water, thereby protecting the electronic circuitry and charged plate in the back volume from being damaged when submerged.
  • the semi-pervious membrane located on the diaphragm is not acoustically transparent, and therefore it reduces the microphone transducer's sensitivity and thereby reduces the signal to noise (S/N) ratio of the generated electrical signal. This also can affect the microphones transducers frequency response.
  • the present invention is provided to solve these and other problems.
  • the icro- phone comprises a housing and a microphone trans ⁇ ducer.
  • the microphone transducer includes a dia ⁇ phragm and a charged plate.
  • the transducer extends across the housing and defines a front volume and a back volume within the housing.
  • a first sound entry port extends through the hous ⁇ ing and is in acoustical communication with the front volume.
  • the back volume is barometrically sealed but for the provision of a barometric relief port ex ⁇ tending through the housing and in communication with the back volume.
  • means are provided for covering the barometric relief port and permitting air to enter and exit the back volume while preventing water from entering and exiting the back volume.
  • the barometric relief port covering means comprises a hydro- phobic membrane, and in particular porous PTFE having a porous diameter of approximately 0.2 microns.
  • the barome- trie relief port has a diameter of approximately 0.020" .
  • the hydrophobic membrane is glued to the exterior surface of the housing by means of a clear epoxy disposed about the periphery of the membrane.
  • the hydrophobic mem ⁇ brane is retained to the housing by means of a strap welded to the housing.
  • Figure 1 is a top view of a water-submers- ible microphone built in accordance with the present invention
  • Figure 2 is a bottom view of the microphone of Figure 1;
  • Figure 3 is a side sectional view of the microphone of Figure 1, taken along line 3-3 thereof;
  • Figure 4 is a side view of the microphone of Figure 1, illustrating one method of attachment of a hydrophobic membrane to the housing;
  • Figure 5 is a side view of the microphone of Figure 1, illustrating a second method of attach ⁇ ment of a hydrophobic membrane to the housing. Description of the Preferred Embodiment
  • a water submersible microphone 10 is illus ⁇ trated in Figures 1-3. But for certain modifica ⁇ tions discussed below, the microphone 10 is an EL Series close-talking, noise cancelling electret microphone, sold by Knowles Electronics, Inc., Itasca IL, the assignee of this application.
  • the microphone 10 comprises a housing 12 having first and second opposing end panels 14, 16, respectively.
  • Each of said first and second end panels 14, 16 have a plurality of 'salt- shaker' type perforations forming spaced sound apertures 14a, 16a, respectively.
  • the microphone 10 further includes a conven ⁇ tional microphone transducer 18 comprising a dia ⁇ phragm 20 and a charged plate 22.
  • the transducer 18 is disposed between the first and second end panels 14, 16, and extends across the housing 12 to define a front volume 26 and a back volume 28.
  • the front volume 26 is located between the first end panel 14 and the transducer 18 and the back volume 28 is located between the second end panel 16 and the transducer 18.
  • the microphone 10 includes power/signal terminals 30, a circuit web 31 supporting a circuit board 32.
  • the circuit board supports an FET preamplifier, which is coupled to the charged plate 2.2 by a gate wire 34.
  • a substantially acoustically transparent shield 36 commonly referred to as a 'spit-guard' extends across the housing 12 within the back volume 28.
  • the shield 36 is glued about its periphery to the housing 12 to make a water-proof seal and divides the back volume 28 into a sealed volume 28a and an open volume 28b.
  • the sealed volume 28a is sealed from the environ ⁇ ment and the open volume 28b is open to the environment.
  • the sealed volume protects the charged plate and the electronics from environ ⁇ mental elements such as dirt.
  • microphones must be operable over a range of barometric pressures.
  • the shield 36 is relatively flexible, changes in barometric pressures affect the pres ⁇ sure within the sealed volume 28a, and hence can affect the static pressure on the diaphragm, negatively affecting operation of the transducer 18.
  • this static pressure was eliminated by the provision of a barometric relief port extending through the transducer 18, which equa ⁇ lized pressure on opposing sides of the transdu- cer 18.
  • the microphone could not be immersed in water, as water would pass through the relief port into the sealed volume, potentially damaging the charged plate and electronics.
  • Hydrophobic membranes which pass only air, but not water, such as porous PTFE have been placed over the diaphragm relief vent to keep water out of the sealed volume; however such hydrophobic membranes are not acoustically transparent and, hence when placed in the sound path, negatively affect the sensitivity of the transducer.
  • the transducer 18 is completely sealed such that no air or water can pass between the front volume 26 and the sealed volume 28a
  • a barometric relief port 38 is provided which extends through the housing 12 and which is in barometric communi ⁇ cation with the sealed volume 28a.
  • a hydropho ⁇ bic membrane 40 covers the barometric relief port
  • the hydrophobic membrane 40 comprises porous PTFE, such as Gore-Tex or Tetratex, having a pore diameter of 0.2 microns. Other pore diameters are available and likely to work as well, though tests have not been conduc ⁇ ted. It is known that the smaller the pore diameter, the greater the water pressure the membrane will withstand before passing water. However, smaller pore diameters also reduce the rate at which air will pass, and thus increase the time it takes for the microphone to compen ⁇ sate for changes in barometric air pressure.
  • the hydrophobic membrane 40 is glued to the exterior surface of the housing 12 by means of a clear epoxy disposed about the periphery of the membrane 40.
  • the hydrophobic membrane 40 is generally square and is retained to the housing 12 by means of an elongated strap 42 which has been tack welded over the membrane 40 at opposing points 42a to the housing 12.
  • the strap 42 has a hole 42a slightly larger in diameter than the barometric relief port 38 to ease assembly.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Abstract

Ce microphone se compose d'un boîtier et d'un transducteur microphonique comprenant un diaphragme et une plaque chargée. Le transducteur s'étend à travers le boîtier et délimite à l'intérieur de celui-ci un volume avant et un volume arrière. Un premier orifice d'entrée du son s'étend à travers le boîtier en communication acoustique avec le volume avant. Un orifice d'évent barométrique s'étend à travers le boîtier en communication acoustique avec le volume arrière. Une membrane poreuse en PTFE recouvre l'orifice d'évent barométrique et permet à l'air d'entrer dans le volume arrière et d'en sortir, tout en empêchant l'eau d'entrer et de sortir de ce même volume.
PCT/US1995/001301 1994-02-03 1995-02-02 Microphone pouvant etre utilise sous l'eau WO1995021512A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU17386/95A AU1738695A (en) 1994-02-03 1995-02-02 Water submersible microphone

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US19140094A 1994-02-03 1994-02-03
US08/191,400 1994-02-03

Publications (1)

Publication Number Publication Date
WO1995021512A1 true WO1995021512A1 (fr) 1995-08-10

Family

ID=22705346

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/001301 WO1995021512A1 (fr) 1994-02-03 1995-02-02 Microphone pouvant etre utilise sous l'eau

Country Status (2)

Country Link
AU (1) AU1738695A (fr)
WO (1) WO1995021512A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1130944A1 (fr) * 2000-03-02 2001-09-05 Asulab S.A. Dispositif d'implantation d'un microphone et d'un organe compensateur de pression dans une montre-téléphone
US6865278B2 (en) 2000-03-02 2005-03-08 Asulab S.A. Device for implanting a microphone and a pressure compensating member in a telephone watch
US7170822B2 (en) 2004-10-07 2007-01-30 Undersea Systems International, Inc. Laminated piezoelectric transducer and method of manufacturing the same
EP1799009A1 (fr) * 2005-12-14 2007-06-20 Undersea Systems International, Inc. Dba Ocean Technology Systems Transducteur piézoélectrique stratifié et son procédé de fabrication
US11467025B2 (en) * 2018-08-17 2022-10-11 Invensense, Inc. Techniques for alternate pressure equalization of a sensor
US11706561B1 (en) 2021-12-23 2023-07-18 Knowles Electronics, Llc Balanced armature receiver with liquid-resistant pressure relief vent

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2709593A1 (de) * 1977-03-03 1978-09-07 Holmberg & Co In einem mikrofon oder funksprechgeraet angeordneter schallwandler
EP0132039A2 (fr) * 1983-06-09 1985-01-23 Robert Bacon Pepper Couvercle résistant à l'humidité pour un transducteur électro-acoustique
EP0533284A1 (fr) * 1991-09-17 1993-03-24 Microtronic Nederland B.V. Transducteur électroacoustique du type électrète
WO1993010644A1 (fr) * 1991-11-15 1993-05-27 Thomson-Csf Membrane d'etancheite pour dispositif acoustique sous-marin

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2709593A1 (de) * 1977-03-03 1978-09-07 Holmberg & Co In einem mikrofon oder funksprechgeraet angeordneter schallwandler
EP0132039A2 (fr) * 1983-06-09 1985-01-23 Robert Bacon Pepper Couvercle résistant à l'humidité pour un transducteur électro-acoustique
EP0533284A1 (fr) * 1991-09-17 1993-03-24 Microtronic Nederland B.V. Transducteur électroacoustique du type électrète
WO1993010644A1 (fr) * 1991-11-15 1993-05-27 Thomson-Csf Membrane d'etancheite pour dispositif acoustique sous-marin

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1130944A1 (fr) * 2000-03-02 2001-09-05 Asulab S.A. Dispositif d'implantation d'un microphone et d'un organe compensateur de pression dans une montre-téléphone
US6865278B2 (en) 2000-03-02 2005-03-08 Asulab S.A. Device for implanting a microphone and a pressure compensating member in a telephone watch
US7170822B2 (en) 2004-10-07 2007-01-30 Undersea Systems International, Inc. Laminated piezoelectric transducer and method of manufacturing the same
EP1799009A1 (fr) * 2005-12-14 2007-06-20 Undersea Systems International, Inc. Dba Ocean Technology Systems Transducteur piézoélectrique stratifié et son procédé de fabrication
EP1819191A2 (fr) * 2005-12-14 2007-08-15 Undersea Systems International, Inc. Dba Ocean Technology Systems Transducteur piézoélectrique stratifié
EP1819191A3 (fr) * 2005-12-14 2007-08-22 Undersea Systems International, Inc. Dba Ocean Technology Systems Transducteur piézoélectrique stratifié
US11467025B2 (en) * 2018-08-17 2022-10-11 Invensense, Inc. Techniques for alternate pressure equalization of a sensor
US12013282B2 (en) 2018-08-17 2024-06-18 Invensense, Inc. Techniques for alternate pressure equalization of a sensor
US11706561B1 (en) 2021-12-23 2023-07-18 Knowles Electronics, Llc Balanced armature receiver with liquid-resistant pressure relief vent

Also Published As

Publication number Publication date
AU1738695A (en) 1995-08-21

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