US2240918A - Device to convert mechanical vibrations into electrical oscillations - Google Patents

Device to convert mechanical vibrations into electrical oscillations Download PDF

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Publication number
US2240918A
US2240918A US214608A US21460838A US2240918A US 2240918 A US2240918 A US 2240918A US 214608 A US214608 A US 214608A US 21460838 A US21460838 A US 21460838A US 2240918 A US2240918 A US 2240918A
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US
United States
Prior art keywords
conductor
mechanical vibrations
electrical oscillations
casing
convert mechanical
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
US214608A
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English (en)
Inventor
Vermeulen Roelof
Fuchs Hermanus Stefanus
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.)
RCA Corp
Original Assignee
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 US2240918A publication Critical patent/US2240918A/en
Anticipated expiration legal-status Critical
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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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/12—Gramophone pick-ups using a stylus; Recorders using a stylus

Definitions

  • This invention relates to an electro-mechanical vibration converter for transforming me chanical vibrations into electrical oscillations.
  • this disadvantage is substantially obviated by movably arranging a conducting rodlike-shaped conductor supported at at least two points within a magnetic field so as to oscillate like a rod between the bearing points.
  • rodlike is used here to express that the conductor is constructed and clampedin free from stresses at the bearing points in such manner that its rigidity plays an important part in determining the natural frequencies.
  • a suitable choice of the dimensions, and the material of the conductor permits of ensuring in this manner that the natural frequencies become located on a very high level although the rigidity at the point at which the mechanical forces to be converted into electrical tensions act is very low. In the case of sound reproduce tion this means that much lower forces at the needle point than hitherto sufiice to obtain a suniciently large conductor amplitude.
  • the needle of pick-ups formed in accordance with the present invention is only subject to low forces so that the pressure at which the needle engages the record may be slight. This results in small wear of the record and the needle.
  • Such pickups can therefore be provided with advantage with a fixed uninterchangeable needle so that also the needle carrier and clamping device may be omitted. This ensures a further reduction in mass of the moving parts so that even very high frequencies, for example 8000 cycles/sec. and more, can be reproduced faithfully by such a vibration converter.
  • Oscillation converters similar to a certain extent to the vibration converters according to this invention but serving for the transformation of electrical oscillations into mechanical vibrations are already known per se, for example mirror oscillographs comprising a wire loop, said wire loop having a current passing through it and being thus moved like a string within a magnetic field.
  • the invention discloses, however, the novel surprising fact that systems of the kind referred to can also be used in those cases, for example in pick-ups, where the conductors are set into vibration by mechanical agency and produce electric currents.
  • the conductor which is supported at two points and which is preferably shaped in the form of a band, is preferably supported rigidly at one of its ends and is set into vibration at its other end which is extended through one of the bearing points on which it is arranged so as to be adapted to move but not to slide in a transverse direction.
  • the conductor is shaped in the form of a band it presents the advantage of being capable of readily oscillating normally to the direction of width but of being rigid in the direction of width.
  • the movably supported end has the needle, in the, case of pick-ups, or the diaphragm, in the case of microphones, fixed to it, it being possible for the space between the bearing points to be closedby an uninterrupted envelope so as to be dust-proof.
  • the two bearing points preferably serve as points for receiving current.
  • Fig. 1 is a longitudinal section of a pick-up according to the invention.
  • Fig. 2 is a cross-sectional view of the said pick-up.
  • Fig. 3 shows in exploded perspective the arrangement of the various elements.
  • l0 designates a cylindrical casing of magnetic material, for instance iron, having connected to it by soldering magnetized pole pieces II and I2 made of magnet steel of high value, for instance a BHmax value of more than 1,500,000 'gauss.
  • the casing I0 is surrounded by a sheath of insulating material l3 and is provided at its lower and upper surfaces with rings l4 and I 5 which are also formed of insulating material so that the upper and lower covers 5 and I! of electrically conductive material, for example aluminium or brass, which are forced onto the coated casing I6 by means of recesses i8 and I9, re spectively, formed in them, are electrically insulated from the casing Iii.
  • the upper cover i8 is closed entirely except for a small bore 29 which is concentrated with the recess 18 and serves for receiving the conductor.
  • the lower cover I! is provided concentrically with the recess It with a collar 2! bearing on the insulating ring I A. of the casing It] and provided with a thread 22. A ring 23 can be screwed into this thread 22.
  • a conductor 25 which is preferably formed of aluminium, has one of its ends s01- dered to the cover it; in the bore 28 and passes through the diaphragm 24; adjacent its other end and is soldered to this diaphragm and is thus capable of rotating at this point to a limited extent but is supported so as to be'prevented from sliding in a transverse direction.
  • the conductor is provided with a tungsten point or a sapphire 28 at this end.
  • This end which extendsfrom the diaphragm, constitutes the scanning needle whosepoint 26 passes in the grooves of the record and thus performs vibrations normal to the plane of the drawing.
  • a damping liquid such, for example, as glycerine or oil on to the diaphragm it.
  • the covers 56 and it are insulated from the casing it and from one another by means of the insulatingsheath i 3 and the insulating rings l4 and IE but each of them is connected electrically to the ends of the conductor 25 so'that the alternating voltage produced in this conductor 25 lies between the said covers.
  • This alternating voltage is transmitted to an amplifying system (not shown) by means of two copper rods 2'5 and 28 which are rigidly connected to the covers it and H, respectively, by means of threads 29 and 33, respectively, and. which also serve jointly as a conducting or supporting arm.
  • the rods are spaced apart and united to form. a mechanical unitary piece by means of a strap 3! of insulating material.
  • the rods may be insulated themselves.
  • An electrical pickup device comprising means providing a magnetic circuit and including an air gap, a conductive element in said air gap, and a pair of conductive members supporting said element at spaced points therealong for movement in said air gap, said element having electrical connection with said members and extending through one of said members whereby to provide an extension adapted to cooperate with a phonograph record.
  • said magnetic circuit providing means includes a normally open-ended casing, and characterized further in that said conductive members close off the endsof said casing.
  • said magnetic circuit providing means includes a normally open-ended casing, characterized further in that said conductive members close oif the ends of'said casing, and characterized still further in that said element is axially aligned with said members.
  • said magnetic-circuit providing means is constituted by a casing of magnetic material having a relatively lowmagnetic value and a pair of pole pieces soldered to the inner Wall thereof, said pole pieces being formed -of magnetic material of relatively high value.
  • An electrical pickup device comprising means providing a magnetic fluxand including an air gap, a conductive element movably mounted in said air gap and including a .tip adapted to cooperate with a phonograph record, a pair of conductive supporting members, and means conductivelycoupling saidmembers with said element, said last-named means constituting a conductive path for conducting to said supporting members voltages generated by the movement of said element in said airgap upon actuation thereof by the record.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Telephone Set Structure (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US214608A 1937-07-28 1938-06-18 Device to convert mechanical vibrations into electrical oscillations Expired - Lifetime US2240918A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE207878X 1937-07-28

Publications (1)

Publication Number Publication Date
US2240918A true US2240918A (en) 1941-05-06

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ID=5793934

Family Applications (1)

Application Number Title Priority Date Filing Date
US214608A Expired - Lifetime US2240918A (en) 1937-07-28 1938-06-18 Device to convert mechanical vibrations into electrical oscillations

Country Status (6)

Country Link
US (1) US2240918A (ko)
BE (1) BE429396A (ko)
CH (1) CH207878A (ko)
FR (1) FR841322A (ko)
GB (1) GB510297A (ko)
NL (1) NL54031C (ko)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473650A (en) * 1943-06-10 1949-06-21 Zenith Radio Corp Phonograph pickup with mechanical filter
US2547361A (en) * 1947-05-19 1951-04-03 Donald J Baker Pickup head using torsional mount for armatures
US2622156A (en) * 1949-01-27 1952-12-16 Donald J Baker Pickup head with removable armature and stylus assembly
US2637920A (en) * 1949-04-28 1953-05-12 Richard H Hallsted Barrier for motor vehicle parking systems
US3207857A (en) * 1959-05-21 1965-09-21 Philips Corp Electrodynamic transducer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473650A (en) * 1943-06-10 1949-06-21 Zenith Radio Corp Phonograph pickup with mechanical filter
US2547361A (en) * 1947-05-19 1951-04-03 Donald J Baker Pickup head using torsional mount for armatures
US2622156A (en) * 1949-01-27 1952-12-16 Donald J Baker Pickup head with removable armature and stylus assembly
US2637920A (en) * 1949-04-28 1953-05-12 Richard H Hallsted Barrier for motor vehicle parking systems
US3207857A (en) * 1959-05-21 1965-09-21 Philips Corp Electrodynamic transducer

Also Published As

Publication number Publication date
BE429396A (ko)
CH207878A (de) 1939-12-15
FR841322A (fr) 1939-05-17
NL54031C (ko)
GB510297A (en) 1939-07-31

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