US1816906A - Electromagnetic device - Google Patents

Electromagnetic device Download PDF

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Publication number
US1816906A
US1816906A US326941A US32694128A US1816906A US 1816906 A US1816906 A US 1816906A US 326941 A US326941 A US 326941A US 32694128 A US32694128 A US 32694128A US 1816906 A US1816906 A US 1816906A
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US
United States
Prior art keywords
flux
armature
gaps
diaphragm
frequency
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
US326941A
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English (en)
Inventor
Warren C Jones
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
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US326941A priority Critical patent/US1816906A/en
Priority to GB28605/29A priority patent/GB340219A/en
Priority to NL48260A priority patent/NL29139C/xx
Priority to FR683390D priority patent/FR683390A/fr
Application granted granted Critical
Publication of US1816906A publication Critical patent/US1816906A/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
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/16—Mounting or connecting stylus to transducer with or without damping means
    • 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
    • H04R11/08—Gramophone pick-ups using a stylus; Recorders using a stylus

Definitions

  • This invention relates to electromagnetic translating devices and more particularly to sound reproducers'and recorders of the oil damped type.
  • the object of the invention is to increase the efficiency of such devices.
  • a four-pole magnetic structure and its associated coil are sealed in an oil filled casing by a flexible diaphragm.
  • a T-shaped armature supported by the diaphragm vibrates with it as the stylus flexes the diaphragm about its diameter.
  • the fourpoles of the magnet system are arranged so that the magnetic circuit has four gaps with respect to the armature and so that the dia phragm does not form an essential part of it.
  • the axis of fiexure of the diaphragm is also the pivot axis for the armature, thereby efiectively closing the oil chamber without clamping the armature vibrations.
  • FIG. 1 is a sectional elevation of a sound translating device incorporating the features of this invention.
  • Fig. 2 is a sectional elevation of a sound translating device incorporating the features of this invention.
  • Fig. 3 is a crosssection on the line 3 3 to show particularly the magnetic circuit and the provisions made for adjusting theair-gaps.
  • Fig. 4 is a crosssection of an alternate arrangement of the magnetic circuit but embodying the same general ideas.
  • Fig. 5 shows the flux distribution when the armature is in its neutral position.
  • Fig. 6' shows the flow of flux when the device is actuated as a reproducer.
  • Fig. 7 shows the flux distribution in the magnetic circuit just prior to. the operation of the device WllGIl'IlSGd as a recorder, and
  • Fig. 8 is a representation ofthe. analogs of the mechanical elements of this device used. as a recorder, in the elements of a corresponding electrical network.
  • the reedmember 1 forming a part of the T-shaped armature 2 pro trudes through .the diaphragm 3 and be tween the coils 44 to aposition midway be-
  • the magnet member 7 also forming a part of the armature, is soldered to the diaphragm to form gaps 8 and 9 adjacent to the pole pieces 10-10.
  • the pole pieces 6 and 10 are welded together or riveted, as indicated, and extend under the poles of the U-shaped magnet 11 which is firmly held in place by means of a clamp 12 secured to the casing 13.
  • the spacing of the pole pieces is maintained by means of a brass channel piece 14 welded or riveted to them.
  • a rectangular opening 15 in the channel 14 permits easy observation of the position of the armature in the gaps and 21.
  • this device when used as a recorder may be more easily understood by referring to Fig. 7.
  • the can rents representing the sounds to be recorded will be conducted to the COilS4l.
  • the flux distribution due to the magnet 11 will be as indicated in Fig. 5 and is represented in this case by long dashes.
  • a current pulse through the coils in such a direction as to give rise to a downward flux through each coil as indicated 7 by short dashes.
  • the flux in gaps 8 and 21 is increased while the flux in gaps 9 and is decreased so that the armature will tend to move in a clockwise direction, current through the coils in the reverse direction similarly will cause the armature to move in a contraclockwise direction.
  • the amplitude and frequency of this motion will, therefore, correspond at all times to the strength and fre quency of the currents in the coils.
  • the alternate construction Shown in Fig. 4% differs from that already described essentially in that a single coil 23 surrounds the armature and replaces the two coils 44l.
  • the lower pole pieces 1 010 are, therefore, modified to pass around the coil as shown
  • a steady flux will flow in the pole pieces 6'-6 and 10'-10 as in the previous case.
  • a deflection of the reed member to the right will cause flux to A flow upward and a deflection to the left will cause flux to flow downward in the reed memher as before.
  • These variations of flux will induce electromotive forces in the coil 28 which obviously will correspond to the movements of the stylus.
  • the necessary damping for this device is provided preferably by substantially filling the casing with a viscous medium 26 as indicated, which impedes the oscillations of the mov ng system and thereby prevents undue response at resonant frequency. 7
  • cordance with the present usual method of and m and (n are 211' times f and f studying mechanical systems. This method is discussed in such well known texts as Electrical Vibration Instruments by A. E. Kennely and in various patents such as 1,678,116 to Harrison, July 24, 1928.
  • the ratio for the device operating as a recorder will be the reciprocal of the impedance ratio or where V and Z are the velocity and impedance of the needle point respectively, at frequency f, and V and Z arc the armature velocity and impedance at frequency f Similarly E n112 0 Znp2 112 From this it follows that where V and V are the armature velocities at resonant frequency f and frequency f re- 4 spectively, and subscripts associated with the impedances also refer to the particular frequency at which they are considered.
  • the denominator of the first part of this equation may be written which at resonant frequency f is simply 1 and the equation then becomes canceling out jS from the numerator and denominator and substituting for 2 this becomes sa+sn 3 1 f2 needle in the reproducer equation, the net reactive component is smaller and that the total impedance is further reduced by the ratio f2 since, as already pointed out, f is near the upper end of the frequency range.
  • the moving system of this invention has a large damping area as compared with many previous devices, due to the large surface of reed member, so that in general a damping medium of somewhat lower viscosity than that commonly used heretofore should he sattisfactory.
  • a vibration translating device a casing containing viscous matter, a magnetic structure having four working gaps within the casing, an armature and a diaphragm forming aclosure for the casing and a pivot for the armature substantially equidistant from all the gaps.
  • a vibration translating device a casing containing viscous matter, a diaphragm forming a closure for the casing,
  • a magnetic circuit having four Working gaps independent of the casing and the diaphragm and an armature pivoted on the device by means of th diaphragm and operating in the gaps ofthe circuit.
  • a vibration translating device a casing containing viscous matter, a diaphragm forming a closure for the casing, a stylus for flexing the diaphragm, a winding and a 10 magnetic circuit including bifurcal polar extensions and a T-shaped armature in operative relation to the inding and pivoted on the reproducer by means of the diaphragm so as to form a plurality of gaps with the 35 polar extensions.
  • a mag net system including bifurcal pole-pieces in spaced relation, a T:shaped armature between the pole-pieces and means for simul- 20 taneously adjusting the pole-pieces With respect to the armature Without disturbing the spaced relation.
  • a magnet system including a plurality of bifurcal 5 polar extensions in spaced relation, a diaphragm, an armature pivoted on the device by means of the diaphragm to form gaps With the polar extensions substantially equidistant from the ivot and means for adjust- 3-3 ing the gaps witiiout disturbing the spaced relation.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electromagnetism (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US326941A 1928-12-19 1928-12-19 Electromagnetic device Expired - Lifetime US1816906A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US326941A US1816906A (en) 1928-12-19 1928-12-19 Electromagnetic device
GB28605/29A GB340219A (en) 1928-12-19 1929-09-20 Improvements in electromagnetic devices for reproducing or recording sound
NL48260A NL29139C (enrdf_load_stackoverflow) 1928-12-19 1929-09-27
FR683390D FR683390A (fr) 1928-12-19 1929-10-16 Perfectionnements aux dispositifs électromagnétiques pour la traduction des vibrations, particuliè rement applicables à l'enregistrement et à la reproduction des sons

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US326941A US1816906A (en) 1928-12-19 1928-12-19 Electromagnetic device

Publications (1)

Publication Number Publication Date
US1816906A true US1816906A (en) 1931-08-04

Family

ID=23274434

Family Applications (1)

Application Number Title Priority Date Filing Date
US326941A Expired - Lifetime US1816906A (en) 1928-12-19 1928-12-19 Electromagnetic device

Country Status (4)

Country Link
US (1) US1816906A (enrdf_load_stackoverflow)
FR (1) FR683390A (enrdf_load_stackoverflow)
GB (1) GB340219A (enrdf_load_stackoverflow)
NL (1) NL29139C (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2508783A (en) * 1945-02-16 1950-05-23 Lionel B Cornwell Electrical sound translating device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2508783A (en) * 1945-02-16 1950-05-23 Lionel B Cornwell Electrical sound translating device

Also Published As

Publication number Publication date
NL29139C (enrdf_load_stackoverflow)
GB340219A (en) 1930-12-22
FR683390A (fr) 1930-06-11

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