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Патент USA US2406597

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Aug. 27, 1946.v
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H1 „Us
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`2,406,597
ELECTRIC PICKUP
Eiled Sept. 7, 1944"
Harold T. Paus,
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H is Attorneg.
Patented Aug. 27, 1946
2,406,597
'_'.,UNITED STATESPATENT OFFICE
ELECTRIC PICKUP
Harold T. Faus, Lynn, Mass., assígnor to Gen
eral Electric Company, a corporation of -New
kYork
Application September 7, 1944, Serial No. 553,019
6 Claims. (Cl. 17a-100.41)
1
My ‘invention relates to Vibration translating '
devices, such as phonograph pickups, and partic
ularly to such devices of the electromagnetic type
having movable coils.
'
'
Yltis an object of my invention to provide an
improved electric pickup of simple and rugged
construction and‘having a moving system oi very
loW- inertia.
j
, .
`
,
; - yItis another object of my invention to provide
`an ¿improved phonograph pickup having a vvibrat
able stylus arm and associated coil oi very light
weight and low inertia which will track inthe
2
¿LV The details of construction of the pickup 5
are clearly shown in Figs. 2 to 5, inclusive. - The
supporting head of the pickup includes a block
Il] ofV rigid insulating material secured in the end
of the tone arm 2 by a setscrew Il. A magnet
structure l2 and a weight i3 are rigidly secured to
*l theblock I0 by a screw' ld. The stylus 6 is
mounted onthe core structure l2 and a ycoil l5
is secured on a nonmagnetic support i6 of alu
10 minum'or other suitable light material which is
connected rigidly to thel stylus 6 for Vibration
therewith. The coil l5 is provided with termi
sound groove of a record with very slight pressure
nals il, which are connected to the leads 9
on the stylus.~
through suitable conductors i8 secured to .the
The features of my invention which I believe to 15 block l0 byvscrews I3, only one of the conductors
be novel are set forth with particularity in the
i8 and screws I9 being shown on the drawing.
appended claims. My invention itself, however,
A shield 25 enclosing the sides and bottom of
both as to its organization >and method of opera~
the’ pickup and held on the tone arm 2 by a col
tion, together with further objects and advan
lar 2| is provided to enclose the pickup, and a
tages thereof, may best be understood by refer
cover 22 is secured over the front and top of the
ence to the following description taken in con
pickup and held in place by a screw 23. The
nection with the accompanying drawing in which
cover 2i! is provided with an opening 24 at its for
Fig'. 1 represents a portion of a phonograph pro
ward end and the stylus 6 extends beyondvthe
vided with a pickup> embodying my invention;
Fig. 2 is -an enlarged view, partly in section, of
the pickup head shown in Fig. 1; Fig. 3 is a View,
,partly broken away, 01,1 the line 3-3 of Fig. 2;
pickup through the opening 24 into position for
25 engagement with the sound track of a record.
As shown in Figs. 3 ande, the magnet struc
ture i2 comprises two bar magnets 25 and 26
4 is a bottom plan View of the portion of the
yoked together at their top ends by a »bar 2l of
pickup shownA in Fig. 3; and Fig. 5 is an enlarged 30 magnetic material. A block 2S of brass or other
sectional View of the stylus arm and coil assem
suitable nonmagnetic material is soldered or
otherwise rigidly secured within the magnetic
Referring now .to the drawing, the phono
structure in engagement with the magnets 25 and
graph in Fig, 1 comprises a turntable `l and a
25 and the yoke 27. The lower ends of the mag
tone arm 2 both of which are mounted on a suit,
nets 25 and 26 are provided with pole pieces 29
35
able supporting structure a portion of which is
and 30, respectively, which are spaced apart
indicated at 3, the turntable being driven in the
at the lower end of the structure and have faces
usual manner by a motor mounted Awithin the
of .circular cross section, as indicated in Fig. 4.
supporting structure. The tone arm 2 is pivot
The block 23 is somewhat shorter than the bar
ally mounted on a bracket 4 rotatably mounted 40 magnets and a core 3l of magnetic material is
in the support 3, and a pickup 5 is mounted
secured in the block 28 in a recess 32 as indi
bly of the pickup.
onthe arm 2 in
mounted on the
track of a record
of the tone arm
a position such that a stylus 6
pickup may engage the sound
'l on the turntable. The weight
cated in Fig. 5. The stylus 3 and coil l5 are re
siliently mounted on the core 3|, the coil l5 being
concentric with the faces of the pole pieces 29
and pickup to the right of the 45 and 30.. The details of construction of the stylus
bracket 4 is balanced by a suitable counterweight
arm and coil assembly are clearly shown in Fig. 5.
B to the left of the bracket 4 so that a very small
The stylus 5 is mounted in a sleeve 33 whichvhas
unbalanced weight remains for holding the stylus
a pin 34r projecting upwardly from the other end
6 on the record. Electric voltage variations pro-thereof. The sleeve 33 is provided with an annu
duced by the pickup 5 in accordance with vibra 50 lar shoulder 35-and the coil support IS is securely
tions of the stylus 6 are amplified by suitable ap
mounted on the sleeve 33 in engagement with
-paratus (not shown) which is connected to the
the shoulder 35. The stylus arm thus comprises
pickup through Wire leads 9 the ends of which
the pin 34 and the sleeve 33 with the stylus 6
have been indicated as entering the interior of
supported in the lower end of the sleeve. The
the structure 3 through the base of the bracket
stylus is preferably a sapphire or other suitable
2,406,597
and means including a coil spaced from and sur
jewel. The magnetic core 3l is of circular cross
section and has an enlarged portion 36 mounted
rounding said core between said pole pieces and
supported solely by said stylus arm for trans
lating into electrical variations the vibrations of
said stylus.
in alignment with the pole pieces 29 and 30 and
equally spaced from the pole pieces. The core 3|
is provided with a downwardly opening central
2. An electric pickup or the like comprising a
supporting head, a permanent magnet structure
mounted on said head and providing two spaced
recess 31, and a block 38 of rubber or other suit
able resilient material is positioned in the re
cess, and the pin 34 is pressed into a central open
pole pieces, a magnetic core supported on said
ing 39 in the block 38. The coil supporting mem
head between said pole pieces and spaced there-.
ber I6 comprises a conical lower portion and a 10 from, said core having a recess therein opening
cylindrical upper portion arranged between the
outwardly between said pole pieces, a stylus arm
pole pieces 29 and 30, the coil l5 being mounted
having a stylus at one end thereof and being
on this upper portion'concentrically with the pin
resiliently supported at its other end in the recess
34 and the core 3|. The magnets 25 and 26 are
in said core, said stylus arm extending outwardly
arranged to produce flux in the same direction
from said head for holding said stylus in a posi
between the pole pieces and when the stylus 6 is
tion for engagement with a record sound track,
displaced laterally, as viewed in Fig. 5, the coil ' and means including a coil spaced from and sur
l5 rotates about an axis at right angles to the
rounding said core between said pole pieces and
flux path between the pole pieces and passing
through the upper portion of the pin 34. This 20 supported solely by said stylus arm for trans
lating into electrical variations the vibrations of
motion generates a voltage in the coil which is
said stylus.
proportional at any instant to the velocity of the
3. An electric pickup or the like comprising a
movement of the stylus. Any displacement of
supporting head, a permanent magnet structure
the stylus at right angles to the lateral displace
ment will produce no voltage in the coil since both 25 mounted on said head and providing two spaced
pole pieces, a magnetic core supported on said
sides of the coil will be moved in the same di
head between said pole pieces and equally spaced
rection through the ñeld between the pole> pieces.
The structure of the pickup is suiñciently rigid
to prevent any resonant vibrations at audible fre
quencies and since the moving mass associatedv 30
with the coil l5 is extremely small the stylus 6
can follow accurately the variations of the sound
track of a record.
During the operation of the phonograph a rec
ord 1 is placed on the turntable I which is ro
therefrom, said core having a central recess
therein opening outwardly between said pole
pieces, a stylus arm having a stylus at one end
thereof, a block of resilient material arranged in
said recess for supporting said stylus arm and
for holding said stylus in a position for engage
35 ment with a record sound track, and means in
cluding a coil spaced from and surrounding said
core between said pole pieces and supported solely
the stylus 6 in engagement with the sound groove
by said stylus arm for translating into electrical
of the record. The stylus is vibrated laterally
variations the vibrations of said stylus.
in accordance with the sound track and the coil
4. An electric pickup or the like comprising a
l5 oscillates about its above mentioned axis 40 supporting head, a permanent magnet structure
through the upper portion of the pin 34 and pro
mounted on said head and providing two spaced
duces voltage variations corresponding to the vi
pole pieces, a magnetic core supported on said
brations of the stylus. These voltage variations
head between said pole pieces and equally spaced
tated while the pickup 5 is placed in position with
are amplified in the usual manner by suitable
ll5 therefrom, said core having a recess therein
apparatus connected to the leads 9.
opening outwardly between said pole pieces, and
From the foregoing it is readily apparent that
a stylus arm having a stylus at one end thereof
I have provided a phonograph pickup of simple
and being resiliently supported at its other end
and rugged construction which may be made
in the recess in said core, said stylus arm ex
with a very small moving mass so that the stylus
tending Youtwardly from said head for holding
may acurately follow a record sound track over
said stylus in position for engagement with a
a wide range of audible frequencies.
While I have illustrated my invention in con
nection with a particular form of phonograph
pickup, other applications will readily be ap
parent to those skilled in the art. I do not, there
fore, desire my invention to be limited t0 the par
ticular arrangement illustrated and described,
and I intend by the appended claims to cover all
modifications which fall within the spirit and
scope of my invention.
y
record sound track, a hollow member secured to
said stylus arm outwardly of said core and hav
ing a portion between said core and said pole
55 pieces and concentric with respect to said core,
and means including a coil on said concentric
portion of said member for translating into elec
trical variations the vibrations of said stylus.
5. An electric pickup or the like comprising a
60
What I claim as new and desire to secure by
Letters Patent of the United States is:
1. An electric pickup or the like comprising a
supporting head, a permanent magnet structure ` ~
supporting head, a U-shaped permanent magnet
structure mounted on said head and providing
two spaced pole pieces, a body of nonmagnetic
material supported within said structure, a mag
netic core supported on said body of materialand
mounted on said head and providing two spaced 65 having a portion ’extending between said. pole
pieces and equally spaced therefrom, said lcore
pole pieces, a magnetic core supported on said
having a recess Vtherein opening' outwardly be
head between said pole pieces and spaced there
tween said pole pieces, a stylus rarm having a
from, a stylus arm having a stylus at one end
stylus at one end thereof and being resiliently
thereof, means including a block of resilient ma
terial for supporting the other end of said stylus 70 supported at its other end in therecess in said
core, said stylus arm extending outwardly from
arm on said core with said arm extending out
said head for holding said stylus in a position for
wardly for holding said stylus in a position for
engagement with aV record sound track, and means
engagement with a record sound track, said
including a coil surrounding said core between
said pole pieces and supported solely by _said
75
connection between said stylus and said core,
block of resilient material constituting the sole ~
5
2,406,597
6
stylus arm for translating into electrical vari
said
pole
pieces
and
opening
outwardly, a stylus
ations the vibrations of said stylus.
arm having a stylus at one end thereof and hav
6. An electric pickup or the like comprising a
ing its other end resiliently supported in there
supporting head, a magnetic structure compris
cess
in said core, said stylus arm extending out
ing two bar magnets having a. connecting yokel 5 wardly
from said head for holding saidy stylus
at one end and separate spaced pole pieces at the
in a position for engagement with a record sound
other end, a body of nonmagnetic material rigid
track, and means including a coil surrounding
ly supported between said bar magnets, a core
said core between said pole pieces and supported
of magnetic material (supported on said body of
solely by said stylus arm for translating into elec
material and having a portion arranged between
said pole pieces and equally spaced therefrom,
said core having a central recess therein between
10 trical variations the vibrations of said‘stylus.
HAROLD
FAUS.
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