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US2566849A - Electroacoustic transducer - Google Patents

Electroacoustic transducer Download PDF

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Publication number
US2566849A
US2566849A US704483A US70448346A US2566849A US 2566849 A US2566849 A US 2566849A US 704483 A US704483 A US 704483A US 70448346 A US70448346 A US 70448346A US 2566849 A US2566849 A US 2566849A
Authority
US
United States
Prior art keywords
armature
transducer
spacer
diaphragm
magnetic
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
US704483A
Other languages
English (en)
Inventor
Edward E Mott
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.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories 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
Priority to NL71172D priority Critical patent/NL71172C/xx
Priority to BE473856D priority patent/BE473856A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US704483A priority patent/US2566849A/en
Priority to FR946542D priority patent/FR946542A/fr
Priority to GB27761/47A priority patent/GB646164A/en
Application granted granted Critical
Publication of US2566849A publication Critical patent/US2566849A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R13/00—Transducers having an acoustic diaphragm of magnetisable material directly co-acting with electromagnet
    • 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

Definitions

  • This invention relates to electroacoustic ⁇ transducer and more particularly to such transducers of the ring armature type such as disclosed in Patent 2,249,160, granted July l5, 1941 to Edward E. Mott.
  • One object of this invention is to simplify the construction of electroacoustic transducers of the ring armature type and, thus, to facilitate the manufacture of such devices in quantity and at relatively low cost.
  • Another object of this invention is to improve the performance of such transducers.
  • Electroacoustic transducers of the ring armature type comprise, in general, an annular magnetic system including a ring armature to which a lightweight diaphragm member is coupled.
  • the magnetic system includes also a permanent magnet which advantageously, in order to reduce the Weightfand size of the transducer and to provide the large polarizing flux requisite for efficient and high power translation of signals, is made of a high magnetic strength alloy, such as Alnico.” Such alloys are extremely hard and difficult to machine.
  • the requisite small and accurate air-gap in any transducer and the substantial identity of the air-gaps in a multiplicity of transducers are attained facilely and with minimum working of the magnet.
  • the inner polepiece is provided with a ange remote from the pole tip thereof, and the magnet is seated upon the iiange and serves as the outer pole-piece.
  • One end face of the magnet is made accurately coplanar with the pole tip of the inner pole-piece and the armature is seated upon ⁇ a spacer in turn seated upon the end face of the magnet.
  • the air-gap between the armature and inner pole-piece is xed by the thickness of the spacer.
  • the air-gap of desired length is realized by mere association of the armature, spacer and pole-piece magnet assembly.
  • improved perfomance may be realized by i providing an auxiliary magnet opposite the1armature and the pole faces of the main magnetic structure.
  • a low reluctance path i is provided between the auxiliary magnet and the main magnetic structure whereby the magnetic etliciency of the transducer is increased.
  • this diaphragm member is formed of a synthetic'jplastic fibre cloth impregnated with a phenolic condensation product.
  • an auxiliary signal coil coupled to the alternating current flux path of the niagnetic system is provided in series with the maii signal coil, thereby to increase the linkage to the signal 1 flux and effect an increased force factor for the transducer.
  • Fig. l is a cross-sectional View of an electroacoustic transducer illustrative of one embodiment of this invention
  • Fig. 2 is a fragmentary sectional view of a portion of the transducer illustrated in Fig. l showing the paths for the biasing or polarizing; and signal fluxes in the magnetic system;
  • Fig. 3 is a View in cross-section of a transducer illustrative of another embodiment of this invention.
  • Fig. 4 is a plan view taken along plane 4--4 of Fig. 3;
  • Fig. 5 is a plan view of one form of diaphragm and armature assembly which may be employed in a modification of the transducers illustrated in Figs. 1 and 3; I
  • Figf' is a sectional view taken along plane G-B of Fig. 5; and y Fig. 7 is a plan view of a modification of the armature included in the transducers illustrated in Figs. 1 and 3.
  • the transducer illustrated in Figs. l and 2 which may be utilized either for translating sound into electrical signals upon assembly oi the device.
  • the several parts of the device may be taken from stock and assembled facilely to produce in quantity transducers having essentially the same operating characteristics.
  • a plurality of individual, equally spaced pole-pieces 29 may be employed in place of the single polepiece l0, I I in the transducer illustrated in Fig. 1.
  • Each pole-piece has thereon a signal coil 30; the several coils may be connected in series aiding or in parallel.
  • may be provided with apertures 3l having acoustic resistance material 32 extending thereacross.
  • apertures together with the chamber between diaphragm l5 and plate 2
  • a transducer of the type i1- lustrated operating either as a receiver or a transmitter, is directly dependent upon the amplitude of the diaphragm vibrations.
  • Enhanced vibration may be obtained by employing a diaphragm-armature assembly of the construction illustrated in Figs. 5 and 6.
  • the diaphragm comprises a central dish- -ed portion 33 and an integral, annular peripheral portion 34 provided with stiffening flutes or ribs 35.
  • the armature is aiiixed to the diaphragm portion 34 and, as shown in Fig. 6, is of less Width than this portion.
  • the diaphragmarmature assembly may be mounted upon the spacer I3 in the same manner as the assemblies illustrated in Figs. 1 and 3.
  • the diaphragm portion 34 it will be noted, constitutes a lever whereby the amplitude of displacement of the diaphragm portion 33 in response to vibration of the armature is increased.
  • the response of a transducer is dependent also upon the stiffness of the armature I4. Magnetic considerations restrict the thinness of armature that can be employed to best advantage. However, the radial width of the armature can be varied substantially without substantial degradation of the operating efficiency, thereby to adjust the armature stiffness to a desired value and x the resonant frequency of the vibrating system.
  • Changes in armature stiffness by varying the radial width of the armature are accompanied, for a given armature thickness, by changes in the armature mass; For a given armature thickness and width, the armature stiffness may be reduced substantially by providing the armature with radial slots 36 asillustrated in Fig. 7.
  • An electroacoustic transducer in accordance with claim l comprising an annular non-magnetic member seated upon said spacer and having a ange portion extending between said armature and said magnetic member and spaced from said armature.
  • An electroacoustic transducer comprising a magnetic circuit including a permanent magnet and having coaxial, inner and outer annular pole faces, an annular magnetic spacer seated upon the outer pole face, an annular magnetic armature seated adjacent its periphery upon said spacer and having its inner edge portion in juxtaposition to the inner pole face, a nonmagnetic spacer seated upon said rst spacer, an annular magnetic member overlying said armature and seated upon said second spacer, and an annular magnetic member interposed between said first magnetic member and said outer pole face.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
US704483A 1946-10-19 1946-10-19 Electroacoustic transducer Expired - Lifetime US2566849A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL71172D NL71172C (da) 1946-10-19
BE473856D BE473856A (da) 1946-10-19
US704483A US2566849A (en) 1946-10-19 1946-10-19 Electroacoustic transducer
FR946542D FR946542A (fr) 1946-10-19 1947-05-12 Convertisseurs électro-acoustiques
GB27761/47A GB646164A (en) 1946-10-19 1947-10-16 Improvements in or relating to electroacoustic transducers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US704483A US2566849A (en) 1946-10-19 1946-10-19 Electroacoustic transducer

Publications (1)

Publication Number Publication Date
US2566849A true US2566849A (en) 1951-09-04

Family

ID=24829716

Family Applications (1)

Application Number Title Priority Date Filing Date
US704483A Expired - Lifetime US2566849A (en) 1946-10-19 1946-10-19 Electroacoustic transducer

Country Status (5)

Country Link
US (1) US2566849A (da)
BE (1) BE473856A (da)
FR (1) FR946542A (da)
GB (1) GB646164A (da)
NL (1) NL71172C (da)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2327668A1 (fr) * 1975-10-09 1977-05-06 Seikosha Kk Vibreur

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1331469A (en) * 1919-06-25 1920-02-17 Stewart Gatter L Telephone-receiver
US1439785A (en) * 1922-04-20 1922-12-26 Eisemann Magneto Corp Telephone receiver of the watchcase type
US1455745A (en) * 1919-05-09 1923-05-15 Henry C Egerton Diaphragm for dictaphones, etc
US1708943A (en) * 1921-09-22 1929-04-16 Western Electric Co Acoustic device
US1800573A (en) * 1929-01-12 1931-04-14 Skala Res Lab Inc Diaphragm
US1830160A (en) * 1928-03-19 1931-11-03 French Electric Company Telephone receiver
US2003908A (en) * 1934-04-25 1935-06-04 Bell Telephone Labor Inc Acoustic device
US2044608A (en) * 1935-05-03 1936-06-16 Du Pont Viscoloid Co Diaphragm for electrical reproduction of sound
US2077425A (en) * 1932-12-24 1937-04-20 Lieber Patents Corp Bone conduction hearing-aid
US2141595A (en) * 1937-01-13 1938-12-27 Cinaudagraph Corp Magnet structure
US2170571A (en) * 1936-08-12 1939-08-22 Bell Telephone Labor Inc Acoustic device
US2249160A (en) * 1939-05-19 1941-07-15 Bell Telephone Labor Inc Acoustic device
US2360796A (en) * 1940-11-29 1944-10-17 Int Standard Electric Corp Electroacoustic device
US2395166A (en) * 1942-12-24 1946-02-19 Astatic Corp Transducer
US2404727A (en) * 1944-12-14 1946-07-23 Du Pont Dissolving of polymers

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1455745A (en) * 1919-05-09 1923-05-15 Henry C Egerton Diaphragm for dictaphones, etc
US1331469A (en) * 1919-06-25 1920-02-17 Stewart Gatter L Telephone-receiver
US1708943A (en) * 1921-09-22 1929-04-16 Western Electric Co Acoustic device
US1439785A (en) * 1922-04-20 1922-12-26 Eisemann Magneto Corp Telephone receiver of the watchcase type
US1830160A (en) * 1928-03-19 1931-11-03 French Electric Company Telephone receiver
US1800573A (en) * 1929-01-12 1931-04-14 Skala Res Lab Inc Diaphragm
US2077425A (en) * 1932-12-24 1937-04-20 Lieber Patents Corp Bone conduction hearing-aid
US2003908A (en) * 1934-04-25 1935-06-04 Bell Telephone Labor Inc Acoustic device
US2044608A (en) * 1935-05-03 1936-06-16 Du Pont Viscoloid Co Diaphragm for electrical reproduction of sound
US2170571A (en) * 1936-08-12 1939-08-22 Bell Telephone Labor Inc Acoustic device
US2141595A (en) * 1937-01-13 1938-12-27 Cinaudagraph Corp Magnet structure
US2249160A (en) * 1939-05-19 1941-07-15 Bell Telephone Labor Inc Acoustic device
US2360796A (en) * 1940-11-29 1944-10-17 Int Standard Electric Corp Electroacoustic device
US2395166A (en) * 1942-12-24 1946-02-19 Astatic Corp Transducer
US2404727A (en) * 1944-12-14 1946-07-23 Du Pont Dissolving of polymers

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2327668A1 (fr) * 1975-10-09 1977-05-06 Seikosha Kk Vibreur

Also Published As

Publication number Publication date
BE473856A (da)
FR946542A (fr) 1949-06-07
NL71172C (da)
GB646164A (en) 1950-11-15

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