US2984711A - Gramophone pick-ups - Google Patents

Gramophone pick-ups Download PDF

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Publication number
US2984711A
US2984711A US762584A US76258458A US2984711A US 2984711 A US2984711 A US 2984711A US 762584 A US762584 A US 762584A US 76258458 A US76258458 A US 76258458A US 2984711 A US2984711 A US 2984711A
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United States
Prior art keywords
armature
pick
stylus
coils
core
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
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US762584A
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English (en)
Inventor
Bayliff Raymond William
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Individual
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Individual
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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
    • H04R11/00—Transducers of moving-armature or moving-core type
    • H04R11/08—Gramophone pick-ups using a stylus; Recorders using a stylus
    • H04R11/12—Gramophone pick-ups using a stylus; Recorders using a stylus signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
    • 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

  • the present invention relates to gramophone pick-ups for use with sound records for stereophonic reproduction in which signals from two suitably spaced microphones are recorded as modulations in the same sound groove, the two modulations producing vibrations of the pick-up stylus about two mutually perpendicular axes.
  • theseaxes are displaced by 45 on either side of the vertical.
  • one axis is vertical, corresponding to hill and dale recording, and the other horizontal, corresponding to lateral recording.
  • a pick-up for such a purpose is required to operate in such a manner that interaction between the signal generating systems for the two modulations is of a satisfactorily low order over the acoustic frequency range, and also that in neither set of signals shall the non-linear distortion be significantly greater than is acceptable in a normal monaural system.
  • the present invention has for its object to provide a pick-up whereby these requirements can be met.
  • a gramophone pickup for stereophonic reproduction comprises a ferromagnetic armature adapted to carry a stylus and mounted with freedom of movement in two modes, namely one corresponding to lateral and the other to vertical movernents of the stylus, two separate magnetic cores each provided with a winding and each having pole tips adjacent the armature, and one or more magnets arranged to pass a polarising flux through the cores and armature, the arrangement being such that lateral movements of the stylus produce flux changes substantially only in one of the said windings and vertical movements of the stylus produce flux changes substantially only in the other of the said windings.
  • the armature is elongated, and is mounted for rocking movement about an axis perpendicular to its longitudinal axis between four pole tips. of one core, the rocking movement producing flux changes in a coil surrounding the armature and constituting one of the said windings, and the other core having two pole tips disposed above the armature in such a position that movements of the armature in the direction of its longitudinal axis produce flux changes in one or more coils surrounding the said other core and constituting the other of the said windings.
  • Fig. 1 is a view in part sectional elevational of one embodiment of the invention
  • Fig. 2 is an underside plan view of the embodiment of Fig. 1,
  • Fig. 3 is a view in front elevation of a part of a modification of the embodiment of Figs. 1 and 2.
  • Fig. 4 is a view in side elevation of the part in Fig. 3,
  • Fig. 5 is an underside plan view of another part of the modification of Figs. 3 and 4,
  • Fig. 6 is a circuit diagram showing one form of coil connections that may be used.
  • Fig. 7 is a diagram showing the preferred way in which the connections of Fig. 6 are made.
  • FIGs. 1 and 2 The embodiment illustrated in Figs. 1 and 2 is a modification of the pick-up described in the specification of my application Serial No. 583,074 which is adapted for reproducing from lateral modulation only.
  • anarmature 10 is a mild steel tube 2.5 mm. long, 0.4 mm. outside diameter and 0.0375 mm. wall thickness.
  • the upper end of this armature is rigidly attached to one end of a cantilever supporting plate 11 constituted by a mild steel strip 0.0375 mm. thick having its plane at right angles to the length ofthe armature.
  • the other end of the plate 11 is firmly clamped by means such asare shown in the earlier specification hereinbefore mentioned (but not shown in the present drawings) to the body 13 of the pick-up.
  • the plate 11 is provided with a longitudinal stiffening ridge 14 extending along the centre line of the plate.
  • This ridge has a smaller depth than in the earlier specification in order to increase suitably the vertical compliance C
  • the compliances C and masses M are herein referred to the tip of a sapphire stylus 16 mounted in the lower end of the armature.
  • a pancake-shaped coil 17 is mounted to surround the armature with its axis along the longitudinal axis of the armature.
  • a suitable permanent magnet 33 is provided, fixed rigidly to the pick-up body 13, and soft iron pole pieces 18 of this magnet have pole tips 18' and 18" extending above and below the coil 17 towards the armature.
  • the upper pole tips 18' have their upper surfaces chamfered as shown. The arrangement is such that when the armature is in its rest position the magnetic flux between the pole pieces is in the y direction, no flux traversing the armature longitudinally.
  • the pole pieces 18 with their pole tips constitute one of the two cores referred to, lateral movements of the stylus 16 (in the y direction) varying the flux distribution in this core and correspondingly varying the flux flowing longitudinally through the armature 10 and hence through the coil 17.
  • the other core 28 is constituted by 1.25 mm. diameter Radiometal rod, shaped as shown, and having pole tips separated by an air gap 31 of about 1 mm. These pole tips have their lower extremities approximately 1.0 mm. above the upper end of the armature 10 and the front end of the support plate 11.
  • the core 28 is in two like parts each surrounded by a coil 29, these coils being connected in series.
  • An air gap 30 is provided in the upper part of the core 28 in order to increase the incremental permeability in the presence of a strong magnetic polarising field.
  • the air gap 30 also contributes to rendering the system 28, 29, 3'1 symmetrical about the three major axes, and so achieves a reasonable immunity from the effects of external interfering magnetic fields.
  • the two coils 29 have equal numbers of turns and like dimensions.
  • the coil 17 has one end connected to a contact 34 and its other end connected to a contact 35 to which one end of the series-connected coils 29 are connected, so that the contact 35 is a common contact.
  • the other end of the coils 2 9 is connected to a further contact 36.
  • a negligible output is obtained from the coils 28 which the stylus 16 is driven by a sound groove which is modulated only laterally.
  • the core members 28 are cemented to a mounting block 38, for instance of nonmagnetic plastic which is fixed to the body 13 by means of screws 39 which pass through slots 40* in the block 38.
  • each pole piece 18 has an extension 41 in which is formed a slot 42.
  • the pole pieces are clamped to the body 13 by screws 43 passing through the slots 42.
  • Suitable values of compliance C and mass M (as hereinbeforedefined) in the three directions x, y and z in the pick-up described are as follows:
  • a sum and difference netwonk may be connected between the contacts 34, 35 and 36 of Fig. 1, and output terminals.
  • the network is so constituted that between one pair of output terminals there is produced a voltage L'+V and between the other pair of output terminals there is produced a voltage L'V.
  • the coils 29 are each wound in duplicate thus providing as shown in Figs.
  • Fig. 7 The preferred way of interconnecting the .coils 29 in order to achieve symmetry and reduce the effect on the pick-up of interfering external magnetic fields is shown in Fig. 7, the core members 28 being indicated in phantom. The coils are all wound in the same sense.
  • a gramophone pick-up for stereophonic reproduction comprising an elongated ferromagnetic armature, a stylus at one end of said armature, means supporting said armature with freedom of movement in two modes, namely a mode corresponding to vertical movement of said stylus and a mode corresponding to horizontal move: ment of the stylus, a first winding surrounding said armature, a first magnetic core having four pole tips adjacent said armature, two on each side thereofia second magnetic core having two pole tips adjacent the end of said armature remote from said stylus, magnet means passing polarising flux through said cores and 'said armature, and a second winding surrounding said second core.
  • a gramophone pick-up according to claim'l further comprising three output terminals, two of said terminals being connected to the ends of one of saidwindings and the other said terminal being connected through the other said winding to a tap on said one winding.
  • a gramophone pick-up according to claim 1 further comprising three output terminals, two of said terminals being connected to the ends of one of said windings and the other said terminal being connected through the other said winding to the centre point of said one winding.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Recording Or Reproducing By Magnetic Means (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Moving Of Heads (AREA)
US762584A 1957-10-08 1958-09-22 Gramophone pick-ups Expired - Lifetime US2984711A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB31481/57A GB856829A (en) 1957-10-08 1957-10-08 Improvements in gramophone pick-ups

Publications (1)

Publication Number Publication Date
US2984711A true US2984711A (en) 1961-05-16

Family

ID=10323744

Family Applications (1)

Application Number Title Priority Date Filing Date
US762584A Expired - Lifetime US2984711A (en) 1957-10-08 1958-09-22 Gramophone pick-ups

Country Status (7)

Country Link
US (1) US2984711A (en, 2012)
BE (1) BE571819A (en, 2012)
CH (1) CH363499A (en, 2012)
DE (1) DE1113584B (en, 2012)
FR (1) FR1212894A (en, 2012)
GB (1) GB856829A (en, 2012)
NL (2) NL231921A (en, 2012)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2864897A (en) * 1958-02-17 1958-12-16 Hoffman Electronics Corp Universal phonograph pickup head or the like
US2875282A (en) * 1953-10-06 1959-02-24 Earl M Reiback Binaural phonograph pickup

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB394325A (en) * 1931-12-14 1933-06-14 Alan Dower Blumlein Improvements in and relating to sound-transmission, sound-recording and sound-reproducing systems
US2105916A (en) * 1934-09-05 1938-01-18 Bell Telephone Labor Inc Sound reproducing system
US2114471A (en) * 1936-06-20 1938-04-19 Bell Telephone Labor Inc Sound recording and reproducing system
DE816311C (de) * 1949-05-04 1951-10-08 Telefunken Gmbh Tonabnehmer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2875282A (en) * 1953-10-06 1959-02-24 Earl M Reiback Binaural phonograph pickup
US2864897A (en) * 1958-02-17 1958-12-16 Hoffman Electronics Corp Universal phonograph pickup head or the like

Also Published As

Publication number Publication date
NL103122C (en, 2012)
CH363499A (de) 1962-07-31
NL231921A (en, 2012)
GB856829A (en) 1960-12-21
FR1212894A (fr) 1960-03-28
BE571819A (en, 2012)
DE1113584B (de) 1961-09-07

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