US3729596A - Electrodynamic sound pickup or sound-track cutting device - Google Patents

Electrodynamic sound pickup or sound-track cutting device Download PDF

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Publication number
US3729596A
US3729596A US00137817A US3729596DA US3729596A US 3729596 A US3729596 A US 3729596A US 00137817 A US00137817 A US 00137817A US 3729596D A US3729596D A US 3729596DA US 3729596 A US3729596 A US 3729596A
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coils
stylus
fingers
air gap
pair
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Expired - Lifetime
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US00137817A
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English (en)
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M Toth
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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
    • H04R9/12—Gramophone pick-ups using a stylus; Recorders using a stylus
    • H04R9/16—Gramophone pick-ups using a stylus; Recorders using a stylus signals recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

Definitions

  • ABSTRACT An electrodynamic sound pickup which also functions as a sound-track cutting device, two angularly disposed preferably stereophonic recordings of an engraved sound track are sensed by a phonograph needle mounted at the free end ofa needle arm oscillating about its other end and carrying two transducer coils having their effective coil range disposed in a magnetic air gap formed by two spaced pole shoes opposing each other.
  • the winding planes of the coils are arranged transversely with respect to the longitudinal direction of the needle arm, and one of the two pole shoes is split at its end adjacent the air gap accommodating both coils, so as to form a pair of pole-shoe fingers each extending through the free central space of each of the pair of coils wherein the effective coil portions disposed within the air gap extend along an arc with a center angle not exceeding 90.
  • This construction allows a relatively large amplitude of movement for the coils, whereby, at a defined number of windings, a relatively great number of lines of flux may be intersected. This is desirable because of a high signal or transducer voltage output. But, of course, such a construction is afflicted with the drawback that the moment of inertia of the oscillating system is large, since the path of movement of the coils include a large radius. In addition, a relatively wide air gap must be provided for the safe functioning, the wide gap causing a low field intensity in the air gap.
  • Another known embodiment is constructed in such a way that the planes of the two coils mounted on the needle arm are disposed normal to one another within an air gap of a permanent magnet.
  • a large number 'of windings it is not possible to place the windings side by side in such a construction, but instead they must be superposed, resulting in correspondingly large heights of the coils.
  • This in turn requires an expensive mounting of the high coils on the needle arm, in order to avoid a subsequent oscillation, or a mechanical fading out of the coil.
  • the transducer coils are connected by separate arms of a coupling member to the needle arm and to suspend them from elastic strips secured above the sound pickup in any suitable manner.
  • the axes of the coils are disposed in parallel relation relative to the associated air gap in which the effective coil section oscillates. Since in this construction the coils are spaced in great distance relative to the needle arm, and since the parts required for holding the coils, form an inert mass, these sound pickup systems are afflicted with a frequency-dependent inertia which is disadvantageous with respect to the frequency characteristic of the sound pickup.
  • the object of this invention resides substantially in avoiding the above mentioned disadvantages by providing an electrodynamic sound pickup the construction and oscillating system of which provides a frequency 0 characteristic of the transducer system affected to minimum by dynamic masses and of a compact construction.
  • one of the two pole shoes is split at its end adjacent the air gap for both coils so as to form a pair of pole shoe fingers in such a manner that each one of the pole shoe fingers extends into an through the free central space of each one of the coils, wherein the effective coil portion ranges of each coil extend along an are having a center angle of
  • One of the pair of pole shoes arranged normally relative to each other includes at its end a semicircular recess defining the one end of the air gap, wherein the effective coil portion ranges disposed in the air gaps, and the surfaces of the pole shoe fingers extending through the coils and defining the other side of the air gaps extend in parallel relation to each other.
  • both coils are arranged symmetrically with respect to an imaginary vertical plane extending through the needle arm.
  • the portions of the coils adjacent the needle arm are embedded in a mass of plastic material or adhesive completely surroundings the needle arm.
  • the end of the needle arm disposed opposite to the phonograph needle is secured in a known manner to one of the pole shoes and includes a weakened portion serving as resilient support for the needle arm allowing it to oscillate in any direction, wherein the weakened portion, as compared with the diameter of the needle arm, is formed by a thin wire-like part of metal or plastic material and this weakened portion is surrounded by an elastic cushion.
  • FIG. 1 is a simplified diagrammatic side view of the sound pickup system according to the invention.
  • FIG. 2 is a part front view of the sound pickup system according to FIG. 1 in enlarged scale.
  • the magnet system of the sound pickup includes a permanent magnet 1 to the ends of which a first pole shoe 2 and a bridge or yoke 3 are attached.
  • the second pole shoe 4 extends in parallel relation to the magnet l and is secured to the yoke 3.
  • the materials suitable for these members are well known.
  • the air gap 5 for the pair of transducer coils 6 and 7' is formed at the spaced opposing ends of the pair of pole shoes 2 and 4.
  • the effective ranges 6a and 7a of the coils 6 and 7 are disposed within the air gap 5, while their opposite portions 6b and 7b adjacent the needle arm 8 are embedded in a mass of plastic material or adhesive 9, serving as retaining means, and completely surrounding the needle arm 8 carrying the phonograph needle 10. 7
  • the coils 6 and '7 in the illustrated exemplified embodiment which are disposed transversely with respect to the longitudinal direction of the needle arm 8, have substantially the form of a trapezoid, the longer base lines 6a and 7a of which extend in parallel relation to the shape of the lower semicircular recess of the pole shoe 2 defining the air' gap at one side, while the zone of the shorter base lines 6b and 7b of the coils are secured to the needle arm by means of the rigid mass 9.
  • Both transducer coils are disposed homologously symmetrically with respect to an imaginary vertical plane 1 1 extending through the needle arm 8.
  • the pole shoe 4 disposed normally with respect to the pole shoe 2 has, in order to form two pole shoe fingers 12 and 13 a split end, adjacent the air gap 5 for the pair of coils 6 and 7, wherein these pole shoe fingers 12 and 13 are formed as annular segments and are disposed homologously symmetrically to each other at either side of the imaginary plane 11, one pole shoe finger 12 extending into and through the coil 6 while the other pole shoe finger 13 extends into and through the coil 7.
  • the effective coil portion ranges (in and 7a disposed within the air gap 5 extend, as already mentioned, in parallel relation to the semicircular recess 2a of the pole shoe 2 defining the one ends of the air gap 5, and also in parallel relation to the surfaces 12a and 13a of the pole shoe fingers 12 and 13 extending through the coils 6 and 7 and defining the other ends of the air gaps 5.
  • pole shoe 4 with its finger-like split end has been found to be particularly advantageous with respect to economical production technique; but evidently this pole shoe 4 could be replaced by two pole shoes extending in parallel relation to each other, and through the central free spaces of the coils, in the same manner as already described in connection with the split pole shoe fingers.
  • the needle arm 8 is secured to the pole shoe 4'by means of a brass sleeve inserted into a bore 14 of the pole shoe.
  • the sleeve 15 is secured against axial shifting within the bore 14 by a bolt 16.
  • the needle arm 8 may, in a manner known per se, oscillate in any direction about a weakened portion which is formed, in comparison with the diameter of the needle arm, by a relatively thin wire-like part 17 of metal or plastic material, connecting the sleeve 15 and the needle arm 8 proper which latter is formed by a tubular body.
  • a relatively thin wire-like part 17 of metal or plastic material connecting the sleeve 15 and the needle arm 8 proper which latter is formed by a tubular body.
  • a resilient cushion 18 of rubber surrounding the same is provided, disposed between a contacting surface 19 of the pole shoe 4 and the retaining means 9 surrounding the needle arm 8.
  • This retaining means is connected to a plate 20 of plastic material or hard paper disposed at the side facing the cushion 18 and surrounding the needle arm 8.
  • the rubber cushion 18 is clamped between the contacting surface 19 and the plate 20 under a defined pretension, with the result that centering forces may be applied to the oscillating system in a simple manner.
  • the retaining body 9 for the coils 6 and 7 may be encased completely in a stable layer of paper. in order to save weight, the lower part of the body 9 is formed substantially conical while its upper part, within which the coils are embedded, has a substantially rectangular cross sectional configuration.
  • Soldering contacts 21 are provided at the lower extension of the yoke 3 to which the ends of the coil wires must be soldered in a common manner.
  • the signal voltages are then derived from the contact pins 22 and fed, for example, to a signal voltage amplifier.
  • the conductor extending through the yoke 3 must, of course, be insulated.
  • the above described construction may also be used as a sound track cutting device, wherein the phonograph needle 10 must be replaced by an engraving stylus serving to cut groove-like sound tracks.
  • the signals or cutting voltages are in this case supplied to coils 6 and 7 via the terminals 22 in a known manner.
  • An electrodynamic transducer comprising:
  • a permanent-magnet yoke having a pair of spacedapart poles defining an air gap between them, one of said poles being formed with a pair of codirectionally extending parallel but transversely spaced fingers of generally arc-segmental cross section, the other pole being formed with a semicircular recess overhanging and spaced from said fingers;

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
US00137817A 1970-04-29 1971-04-27 Electrodynamic sound pickup or sound-track cutting device Expired - Lifetime US3729596A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702020903 DE2020903A1 (de) 1970-04-29 1970-04-29 Elektrodynamischer Tonabnehmer oder Schneiddose

Publications (1)

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US3729596A true US3729596A (en) 1973-04-24

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US00137817A Expired - Lifetime US3729596A (en) 1970-04-29 1971-04-27 Electrodynamic sound pickup or sound-track cutting device

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US (1) US3729596A (de)
CH (1) CH521078A (de)
DE (1) DE2020903A1 (de)
FR (1) FR2086458A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4090039A (en) * 1976-07-06 1978-05-16 Sony Corporation Electrodynamic transducer
US4124783A (en) * 1976-12-21 1978-11-07 Kabushiki Kaisha Audio-Technica Phonographic pickup
US4263483A (en) * 1977-09-01 1981-04-21 Matsushita Electric Industrial Co., Ltd. Moving coil pick-up assembly for use in a record player
US4272652A (en) * 1978-05-25 1981-06-09 Nippon Atsudenki K.K. Moving coil type stereophonic pickup cartridge
US4376304A (en) * 1979-06-22 1983-03-08 Nippon Atsudenki Kabushiki Kaisha Moving coil type stereophonic pickup cartridge

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4238646A (en) * 1977-08-10 1980-12-09 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge for reproducing signals recorded on a 45--45 stereophonic record disk
US4317191A (en) * 1979-01-17 1982-02-23 Sony Corporation Moving coil pickup cartridge

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2027168A (en) * 1934-09-05 1936-01-07 Bell Telephone Labor Inc Vibration translating device
US2114471A (en) * 1936-06-20 1938-04-19 Bell Telephone Labor Inc Sound recording and reproducing system
US3142729A (en) * 1957-12-10 1964-07-28 Litton Systems Inc Phonograph reproducer
GB1000035A (en) * 1960-10-22 1965-08-04 Fonofilm Ind As A stereophonic electrodynamic pickup

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2027168A (en) * 1934-09-05 1936-01-07 Bell Telephone Labor Inc Vibration translating device
US2114471A (en) * 1936-06-20 1938-04-19 Bell Telephone Labor Inc Sound recording and reproducing system
US3142729A (en) * 1957-12-10 1964-07-28 Litton Systems Inc Phonograph reproducer
GB1000035A (en) * 1960-10-22 1965-08-04 Fonofilm Ind As A stereophonic electrodynamic pickup

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4090039A (en) * 1976-07-06 1978-05-16 Sony Corporation Electrodynamic transducer
US4124783A (en) * 1976-12-21 1978-11-07 Kabushiki Kaisha Audio-Technica Phonographic pickup
US4263483A (en) * 1977-09-01 1981-04-21 Matsushita Electric Industrial Co., Ltd. Moving coil pick-up assembly for use in a record player
US4272652A (en) * 1978-05-25 1981-06-09 Nippon Atsudenki K.K. Moving coil type stereophonic pickup cartridge
US4376304A (en) * 1979-06-22 1983-03-08 Nippon Atsudenki Kabushiki Kaisha Moving coil type stereophonic pickup cartridge

Also Published As

Publication number Publication date
DE2020903A1 (de) 1971-11-11
CH521078A (de) 1972-03-31
FR2086458A1 (de) 1971-12-31

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