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Патент USA US2104170

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Jan. 4,' 1938.
K. SCHWARZ
‘
‘
SOUND RECORDING DEVICE
2,104,170
'
Filed ‘Nov. 13, 1955
£119.11
25
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INYVENTQR A
KARL SCH/V432
I
#éim"
. ATTORNEY
2,104,170
Patented Jan. 4, 1938
UNITED STATES
‘PATENT OFFICE
2,104,17 0
SOUND RECORDING DEVICE
Karl Schwarz, Berlin, Germany, assignor‘ to
Klang?lm G. m. b. H., Berlin, Germany, a -
corporation of Germany
Application November 13, 1935, Serial No. 49,465
.
In Germany April 15, 1935
.
(Cl. 179-1003)
her which admits of rotational movements of the
This invention relates to signal recording de
5 Claims.
mirror about the longitudinal axis of the string
application Serial No. ‘28,418, ?led June 26, 1935 , support and in that the mounting and adjusting
(D—10,191), and has for its principal object, the means for the string support and the mirror are
rotatable about an axis which forms with the
5 .provision of an improved signal recording mech
string support an angle that corresponds to the
anism and method of operation whereby a re
vices such as that disclosed in my copending
cording element, such as a galvanometer mirror
or the like, is vibrated about one axis in accord
ance with the signal to be recorded and is ro
wrtated about another axis in accordance with the
signal volume. The present invention involves
features similar in some respects to those dis
closed by a copending application of EdwardW.
Kellogg, Serial No. 531, filed Jan. 5, 1935 and
15 assigned to Radio Corporation of America but
differs therefrom in the constructional details
and operating principle of recording mechanism.
The object of the copending application (Se
rial No. 28,418) is the provision of a method and‘
20 means adapted to produce variable area type
records that are free from background noises.
To this end a stationary serrated diaphragm or
light-stop serves to contour and bound a light
pencil or beam, which is caused to impinge upon
25 a mirror oscillated about an axis or pivot at the
frequency of the signal, the said pivot being posi
tioned perpendicularly at right angles to one of
the edges of the stop. This mirror is also moved
in response to the signal volume current about
diaphragm angle. This new arrangement makes
it possible to effect adjustment of the mirror in
the sense of the di?erent coordinates essentially
independently of one another. Inasmuch as the 10
mirror involves very little inertia, it is preferable
that the mirror should be excited about the
string sup-port in accordancewith the signal vi
brations. The supporting and ‘adjusting system
involves far more inertia and is less suited and 15'
able to follow the tonalposcillations. In fact, this
system is called upon to experience comparatively
slow vibrations, say, up to around 20 cycles per
second. These oscillations are due to fluctuations
of the direct current generated by recti?cation N 0of the signal currents, the intensity of which cor
responds to the volume of the sound or signal to
be recorded and is subject to but slight alterations
in comparison with the tonal vibrations.
Inasmuch as it is necessary to provide a mag
net in whose ?eld the mirror excited at tonal fre
quency is capable of oscillating, and since this
25
magnet would greatly increase the weight of the
system which is to vibrate in unison with the sig
another pivot positioned at right angles to the nal volume current, means are provided which 30'
other edge of the stop. The two axes about which make it unnecessary for the magnet to partake
the mirror must be caused to oscillate according of the oscillations of the supporting system. This
is made practicable in that the pole-shoes of the
to the method disclosed in the aforesaid copend
magnet are yieldingly' united therewith. In this
ing patent application, thus form an angle rela
35 tive to each other which is equal to- the ‘angle case, the pole-shoes and more particularly the 03 vi.
tips thereof which govern the intensityof the
formed between two abutting edges of the multi
tooth mask or light-stop. In the case where the magnetic ?eld within which the mirror is made
edges of the multi-serrated light-stop are at right to oscillate, will be able to vibrate in accordance
,
angles to one another; the oscillating mirror, as 'with the signal amplitude or volume, whereas the
40 will thus be seen, must be pivotable about two magnet itself remains at rest. This yielding union 40
axes-being at right angles to each other. This between the pole-shoes and the magnet, however,
must be chosen in such‘a way that the magnetic
special requirement is somewhat vdimcult of ful
?ux in the pole-shoes will be large. It is there
?llment because the space available for the de
vice is limited and replacement of the light valve fore suggested to choose a'high-permeability ma- ,
45 in the sound recorder apparatus is likely to be terial throughout the pole-shoes, and to so taper 45
required.
.
‘
_
'
5
In addition to the di?iculties just ‘outlined,
there are others which are due to the require
ment that the center of the mirror should occupy
50 a de?nite position upon the optical axis, and that
the mirror plane, in its zero position, should be
in a de?nite position with'respect thereto.
According vto the present invention, these di?i
culties are obviated in that the mirror is sup
“ ported ‘by a string, chord or other suitable mem
the same at one place that the pole-shoes can,
be readily bent in accordance with the oscilla
tions of the supporting system. However, the
same end is attainable in that the pole-shoes.
terminate at their ends or tips in a plate or blade 50
of magnetic material, and that the latter is con-,
nected with the magnet with the interposition
of a tenuous layer of yielding or ?exible mate
terial such as ‘rubber or the like. While this
meansa small'gap between the pole-shoe and 551
2,104,170v
the magnet ?lled with material of low permeabil
ity, the magnetic ?ux in the pole-shoes will never
theless be of the requisite intensity on the ground
that the cross-sectional area at this place is con
veniently large.
The magnet, preferably a bar magnet, is dis
posed below the supporting system, and the same
has a central bore through which the driving sys
tem of the noise control means may be shifted’
and made to engage.
Screwed upon the ends of
r'
‘
‘
‘
ing system in relation to the exciting means for
the noise reduction currents effected in a way
as stated, the device is inserted into the casing
of the light valve so that it will thus be protected
in a dust-proof and hermetical way. By the aid 5
of pressure (thrust) and tractile screws, the posi
tion of the oscillation system in reference to the
casing can be adjusted in any desired direction.
The sequence in which the various adjustments
,must be accomplished, and more particularly in 10
‘what Way the system oscillating at tone
frequency must be constructed is described below
in more detail by reference to the drawing illus
rubber may be arranged. ' Owing to the fact that‘ trating one exempli?ed embodiment of the in
the bar magnet are blocks or resting means in
Which the ?exible pole-shoes may be fastened by
clamping action or upon which the said layer of
the said supporting blocks are screwed on, this '
vention.
'
,
,
'
allows adjustment of the center of the mirror. In
Referring to ' the drawing,
fact, by shifting the same conditions can be made
Fig. 1 shows asection laid through the light
so that the center of the 'mirrorwill coincide with ' valve at right angles to the axis about which the
the optical axis.
-
-
I
signal volume responsive oscillations take place,
Fig. 2 shows a section at right angles to the 20
For driving and adjusting the supporting sysé ‘
tem there serves 'preferably'an electromagnetic other axis of rotation of the mirror about which
the signal, responsive vibrations take place, the'
system which is subject to a control action'pro
casing having been omitted'in‘ this ?gure.
,
duced by a current which‘ is responsive to the sig
Fig.‘ 3 is a View of the lightrvalve in the direc
nal amplitude or volume. For this purpose there
25 is rigidly associated with the supporting system
tion of the optical axis after removal, of casing, 25.
a ferro-magnetic body which is hereinafter called and
a tongue or reed whose free end is capable of '
Fig.’ 4 illustrates the mode of clamping the’
oscillating in front of the pole-shoes of a magnet." chord or string of theoscillating mirror.
-The oscillating‘mirror I (Fig. '3) is supported
This driving system is preferably designed so as
to act as a so-called free oscillator. The exciting by a chord 2. In order "to facilitate and simplify
coil embraces at one end the said tongue, while; the fastening of the mirror in reference to the
at the other end it is seated in a ring magnet’ chordas well as'the clamping of the latter, 'a
chord having rectangular cross-sectional'shape
upon the ends of which pole-shoes are screwed
fast, which bound an air-gap‘ in the middle of" as shown in Fig. 4 is used. The clamping and
locking of the chord in the supp‘orting‘system 3
.may be effected in various ways. Thusat both
The supporting vsystem could comprise either a' ends of the chord, bolts 4 provided with grips 5
knife edge system or a mechanical pivot 01'' else may be provided. These bolts’ may be sawed open
be insured by supporting in more than one point, so that the chord may be inserted, and then the
40 provided that, upon eifecting a shift in these sup
parts may be secured in reference to each other
porting points, at least approximately rotation of by suitable clamp screws. By means of guide pins
the supporting system about .the desired axis 28 which are seated in one-half'of the bolt and en
gage in bores 29 of the other half of the bolt,
passing through the mirror is insured.
According to another aspect of this invention, relative slipping of the bolt members or halves
4.5 _ the supporting system bears upon leaf springs the is prevented; ‘By changing the relative distance
of the bolts, the, free length of the chord is alter
ends of which are capable of rotational move
ments about their clamping or securing point. In 7 able and thus‘ also the natural period of the oscil~
latory system comprising the chord and the
order to insure safe contact between the support
>
ing system and the said leaf springs also in case mirror.
The'oscillatory system'j is subject to 'a driving .
50 of transportation, the supporting system is pro
vided, say, with two bore holes through which two action set up by a ferro~magnetic plate on the
strings engage. By tensioning these strings or oscillating mirror, and a magnetic ?eld set up
chords, both the desired bearing pressure as well by ampli?ed microphone currents in the coils 1
as a convenient biasing tension in the leaf springs seated on the pole-shoes. The pole-shoes 6 are
secured upon blocks or’ uprights 8 which are
will be secured.
,
V
'
The said leaf springs are clamped fast in a screwed upon ‘the bar magnet 9. Two types‘of
the magnetic ring and in which, as stated, the said.
tongue is capable of vibrating.
body which, on the one hand,is rigidly united pole-shoe mounting according to this invention
are illustrated inEig. 2. The left-‘hand pole-shoe
with the ring magnets of the ground noise reduc
- in Fig. 2 terminates in'a plateletvlll disposed’ on
tion
drive'
system,
while,
on
the
other
hand
it
60
.serves' to adjust the entire vibrational system in the block 8 with interposition of>_a rubber disk or 60
reference to the casing of the light valve. The washer II. The right-hand pole-shoe‘ shows a_
V65
leaf spring. I2’which permits'thepole-shoe of;ex'
securing of the leaf springs must be accom
plished with a good deal of care in order that the periencing movements in reference to the block.
rotational movements about the desired axis or .Also ‘at this place a rubber buffer is interposed
pivot may result. The leaf springs are locked as indicated at H’. The‘ rubber. disk ll’ serves
in position by screws which in case they have not to‘ dampen or deaden the vibrations of the leaf
been completely tightened allow of a certain spring l2. Also thelayer of rubber on the left
hand pole-shoe has this effect. .»
amount of clearance or play between the springs
Adjustment
of
theinatural
period
of
oscillationI
and the body. When adjusted,'these screws are of the mirror. is’ effected by adjusting the ‘free
tightened and leaf springs and body are con
length of the chord or string which may be altered
nected by pins or tenons in that, after adjustment by means ofthe ends or. grips 5. By shifting the.
has been vperfected, leaf springs and body are
drilled, whereupon a pin is introduced into the
bore hole; After the adjustment of the support
bolts ,4 in the same sense the centerofithe. mirror
may be alinedrwith theoptical axis. ,However,
it is by .no means necessary to make the clamp- 75.
3
2,104,170
ing or ‘securing means for the mirror symmetric.
In fact, in some instances it may be preferable to
fasten one end of the string in a leaf spring, and
to render the opposite end adjustable. When the
proper position for the center of the mirror has
been ascertained, care is required to orientate the
face of the mirror properly with respect to the
chord acting as the axis of rotation. This may
here be effected by turning the bolts in the clamp
10 ing device. After also this setting has been ac
complished, then the bolts are locked by a screw
provided in the supporting system.
The bar maget 9 has a central bore which pro
vides room for a tongue l3 which is fastened on
15 the supporting system 3.
The lower end of the
tongue is oscillated under the in?uence of the
changing magnetic ?eld between the pole-shoes
I4 of a ring magnet l5. This alternating ?eld is
created by the signal volume or amplitude re~
20 sponsive currents in a coil IS. The oscillations of
the supporting system and thus of the mirror
are made possible by the leaf spring supports l'l.
These oscillations are damped or deadened not
only by the said rubber buffer means between
25 pole-shoe 6 and upright or block 8, but in addi
tion damping or buffer means may be inter
posed also between the bar magnet 9 and the
tongue l3, as indicated at l8.
Disposed on the ring magnet I5 is a body l9
30 against which the leaf springs I‘! are clamped
by the screws 20. After ?nal adjustment, pin
or tenon connection is effected by the aid of pins
surface of the optional means, exact adjustment
of the mirror face will be insurable in spite of
the fact that the device is entirely encased.
In lieu of rubber, of course, also other suitable
yielding substances may be employed, provided
that they involve suf?cient internal friction.
I claim:
1. The combination of an assembly comprising
a vibratable member, electrical signal responsive
means operable to vibrate said member about one 10
axis, resilient means supporting said assembly,
and electrical signal volume responsive means
coupled to said assembly and operable to vibrate
said assembly about another axis.
2. The combination of a galvanometer as 15
sembly comprising an electromagnetic element,
a mirror vibratable about one axis in accordance
with the energization of said element, an auxili
ary electromagnetic element, resilient support
ing means interposed between said assembly and 20
said auxiliary electromagnetic element, and cou
pling means connected between said assembly and
said auxiliary electromagnetic means for moving
said mirror about another‘ axis in accordance with
the energization of said auxiliary electromag 25
netic element.
3. A signal recording mechanism of the gal
vanometer type including a magnetic structure,
pole-shoes resiliently supported on said structure,
electrical signal responsive coils cooperatively as 30
sociated with said pole members, and a ?exibly
supported vibratable member interposed between
said
pole-shoes.
2|. The leaf springs I1 terminate in knife edges ,
4. A signal recording mechanism of the gal
at their free ends which engage in the bearing 22
35 of the supporting system. The suporting system
3 is provided with openings 23' through which
chords (not shown) are passed for ensuring that
the supporting system stop properly bears upon
the knife edges. Adjusting and guide screws ‘24
.40 and 25 respectively, are arranged in body IS. The
screws are so set that the heads thereof are in
a plane which is parallel to that of the face of the
mirror I. At the bottom of the case a cover 26 is
screwed off, the light valve is ?tted into the case
and is fastened on the latter by means of tractile
screws 25, and ?nally the bottom 26 is ?tted on
again. By tightening or loosening the screws 25,
it is feasible to set the face of the mirror ex
actly parallel to the ?at surface 21 of the cas
ing.
Inasmuch as the last-mentioned surface,
50
after inserting, is pressed against a matching
vanometer type including a magnetic structure, 35
pole-shoes resiliently supported on said structure
and tapered at their opposed ends, electrical sig
nal responsive coils cooperatively associated with
said pole members, and a ?exibly supported vi- 7
bratable member interposed between said pole
shoes.
49
,
5. In a signal recording mechanism, the com
bination of electrical signal responsive means in;
cluding an electromagnetic structure provided
with an opening and a member vibratable about 45
one axis in accordance with the energization of
said means, an auxiliary electromagnetic respon
sive means coupled to said member through said
opening and operable to vibrate said member
50
about another axis.
KARL SCHWARZ.
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