US2006847A - Electrodynamic magnet system for microphones, loudspeakers, or similar devices - Google Patents

Electrodynamic magnet system for microphones, loudspeakers, or similar devices Download PDF

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Publication number
US2006847A
US2006847A US259445A US25944528A US2006847A US 2006847 A US2006847 A US 2006847A US 259445 A US259445 A US 259445A US 25944528 A US25944528 A US 25944528A US 2006847 A US2006847 A US 2006847A
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US
United States
Prior art keywords
magnet system
annular
secured
electrodynamic
microphones
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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
US259445A
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English (en)
Inventor
Vermeulen Roelof
Arend Thomas Van Urk
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RCA Corp
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RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
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Publication of US2006847A publication Critical patent/US2006847A/en
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    • 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

Definitions

  • the invention relates to an electrodynamic magnet system for microphones, loud-speakers or similar devices provided with wire windings which are movably arranged in a magnetic field.
  • the invention has for its object to guide these windings during their movements in such a manner that at all frequencies and especially at the lower ones an efficiency is obtained which is as favorable as possible,
  • the windings when the windings are moving in the magnetic field, they are kept centered by one or more layers of a substance which possesses a slightly elastic but strongly damping property.
  • the slightly elastic properties involve that the directing force which moves the windings back into their middle-position, is small with the result that the natural frequency of the oscillating portion of the magnet system is very low. If the radiated sound energy is graphically plotted for various frequencies, their curve is obtained which shows a peak at the natural frequency of the oscillating portion of the magnet system. When, consequently, the magnet system oscillates at that frequency, the radiated sound energy will be considerably greater than at other frequencies, which is harmful to the sound reproduced. This disadvantage can be eliminated by damping the movement of the oscillating portion of the magnet system and thereby smoothing out the peak.
  • the magnet system according to the present invention has the advantage that the point of natural resonance comes to lie low while at the same time a strong damping is obtained. Especially at frequencies ranging from 150 to 500 the efficiency of the system will be very favorable.
  • this annular coil is kept centered by discs made of a substance which possesses the above mentioned properties, said discs being secured to the poles or to parts of the magnet system which are immovably connected to the said poles.
  • the coil may be secured to the discs but should preferably not be connected thereto.
  • a disc is further secured to the central pole, another disc being secured to the annular pole.
  • the substance which has the abovementioned properties may consist of textile fabric such as velvet or flannel, but it may also consist of a substance such as felt.
  • Fig. 1 is a graph showing the value of the radiated sound energy at various frequencies of the magnet system according to the invention and Fig. .3 is a sectional view through the driving mechanism of the invention.
  • poles 2 and 3 of a permanent or electromagnet produce together an annular magnetic field in which a coil 4 is movably arranged.
  • the coil 4 is wound on a small tube of cardboard which is directly secured to a cone 5.
  • a felt layer 6 is secured to the pole 2 by means of a screw II, and an annular felt layer I is provided on the pole 3 by means of an annular copper clamping piece 8 and screws 9.
  • the cardboard tube on which the coil 4 is wound slides along the edges of the felt layers 6 and I and is thus kept centered in the annular magnetic field.
  • the felt possesses the property that after being deformed it has only a slight tendency to return into its original position while it exerts a strongly damping influence on the movement of the coil 4.
  • this coil 4 When now this coil 4 is traversed by speech modulated current, it will experience a strong damping during its movements.
  • a strong damping during its movements.
  • several layers of textile fabric such as flannel, serge etc. may be utilized, all of them showing slightly elastic but strongly damping properties.
  • Figure 1 In Figure 1 is indicated the value of the radiated sound energy at different frequencies.
  • the curve a shows the course of a magnet system with which the point of resonance lies very low.
  • the curve b indicates the course of the magnet system of Figure 2.
  • the point of resonance lies at a frequency of 200 while the oscil lations are strongly damped. It appears from the figure that tones with frequencies ranging from 150 to 400 cycles reproduce considerably better.
  • a translating device comprising a magnet system, a vibratile member, a hollow cylindrical member secured to the vibratile member, a coil mounted upon the cylindrical member, a fabric disk fastened to part of said magnet system and positioned to engage said cylindrical member, said fabric disk having slight elastic and strong damping properties.
  • a translating device comprising a magnet system, a vibratile member, a hollow cylindrical member secured to the vibratile member, a coil mounted upon the cylindrical member, and a fabric disk and an annular fabric member fastened to the magnet system and positioned to slidably engage the hollow cylindrical member said disk being slightly elastic.
  • a translating device comprising a magnet system, a vibratile member, a hollow cylindrical member secured to the vibratile member, a coil mounted upon the cylindrical member, and a disk and an annular member of yielding material fastened to the magnet system, said disk engaging the inside of the hollow cylindrical member and said annular member engaging the outside of the cylindrical member.
  • An acoustic device of the electrodynamic type comprising an inner pole piece, an outer pole piece spaced therefrom to form an air gap, 2. vibratile member, a driving member secured to said vibratile member and extending into said air gap, a washer of damping material secured to said inner pole piece and extending outwardly therefrom to engage the inner surface of said driving member, and an annular washer of damping material secured to said outer pole piece and extending inwardly therefrom to engage the outer surface of said driving member.
  • An acoustic device of the electrodynamic type comprising a cylindrical pole piece, an an nular pole piece spaced therefrom to form an annular air gap, a vibratile member, a cylindrical member secured thereto and extending into said annular air gap, a fabric disk secured to the top of said cylindrical pole piece and extending outwardly therefrom beyond the circumference thereof to engage the inner surface of said cylindrical member, and an annular fabric member secured to said annular pole piece and extending inwardly therefrom to engage the outer surface of said cylindrical member.
  • a sound converting device comprising a magnet system, a vibratile member, a hollow cylindrical member secured to the vibratile 7 member, a coil mounted on the cylindrical memher and a fabric disk secured to part of said magnet system and positioned to engage said cylindrical member, said fabric disc being only slightly elastic whereby after being deformed it has only a slight tendency to return to its original position.
  • a sound converting device comprising a magnet system, a vibratile member, a hollow cylindrical member secured to said vibratile member, a coil mounted on the cylindrical member, a fabric disc and an annular fabric member spaced apart and fastened to the magnet system and positioned to slidably engage the hollow cylindrical member said disc and fabric member being slightly elastic.
  • the magnet comprises a central pole and an annular pole and in which said fabric disc is carried by said central pole and said annular fabric member by said annular pole.
  • a sound converting device comprising the combination of a magnet system having an annular airgap and a pole piece located within said gap, a vibratile diaphragm a substantially cylindrical coil form connected to said diaphragm, a substantially cylindrical coil mounted on said coil form and at least two flexible members one being secured to said pole piece and engaging the interior surface of said coil form near one end thereof and the other being secured to said magnet system and engaging the ex-

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Storage Of Web-Like Or Filamentary Materials (AREA)
US259445A 1927-03-25 1928-03-06 Electrodynamic magnet system for microphones, loudspeakers, or similar devices Expired - Lifetime US2006847A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL36431A NL27011C (de) 1927-03-25 1927-03-25

Publications (1)

Publication Number Publication Date
US2006847A true US2006847A (en) 1935-07-02

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ID=32472173

Family Applications (1)

Application Number Title Priority Date Filing Date
US259445A Expired - Lifetime US2006847A (en) 1927-03-25 1928-03-06 Electrodynamic magnet system for microphones, loudspeakers, or similar devices

Country Status (5)

Country Link
US (1) US2006847A (de)
BE (1) BE349115A (de)
FR (1) FR649790A (de)
GB (1) GB292739A (de)
NL (1) NL27011C (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492255A (en) * 1944-12-26 1949-12-27 John O Angehrn Sealed-coil type vibratory magnet loudspeaker
ITAN20090058A1 (it) * 2009-09-09 2011-03-10 Ask Ind Societa Per Azioni Trasduttore magneto-dinamico con sistema centrante

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4235302A (en) * 1977-03-15 1980-11-25 Kenkichi Tsukamoto Loudspeaker
US4239090A (en) * 1979-03-29 1980-12-16 Dahlquist Jon G High accuracy bass reproducer device
JPH09163492A (ja) * 1995-12-06 1997-06-20 Pioneer Electron Corp スピーカ

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492255A (en) * 1944-12-26 1949-12-27 John O Angehrn Sealed-coil type vibratory magnet loudspeaker
ITAN20090058A1 (it) * 2009-09-09 2011-03-10 Ask Ind Societa Per Azioni Trasduttore magneto-dinamico con sistema centrante

Also Published As

Publication number Publication date
BE349115A (de)
FR649790A (fr) 1928-12-27
GB292739A (en) 1928-06-28
NL27011C (de) 1932-06-15

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