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Патент USA US2404026

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Judy E9
l46°
J- Gf BIL-:ARD 'E1-AL
2,404,026
METHODOF AND SYSTEM FOR TRÀNSLATING SIGNALS
Filed. March’ 29, 1944
>OZMD,NÉ
@mi
INVEN TORS.
JOSEPH G~ BEARD.
ROBERT W HARRALSON.
ATTORNEY
Patented July 16, 1946
2,404,025
UNITED STATES PATENT OFFICE
2,404,026
METHOD oF AND SYSTEM Foa
TaANsLA'riNG SIGNALs
Joseph G. Beard, Haddoniield, and Robert W.
Harralson, Masonville, N. J., assignors to Radio
Corporation of America, a corporation of Dela
Application March 29, 1944, Serial No. 528,611
12 Claims. (C1. 179-1004)
l
2
Our present invention relates to signal trans
termined extent from the crystal-controlled fre
lating methods and systems, and more particu
quency of the oscillator.
larly to a novel method of, and system for, trans
Still' another object of our invention is to pro
lating a physical displacement of a mobile ele
vide, in a phonograph record reproduction sys
ment into a corresponding voltage through the Ul tem, an oscillator which is crystal-controlled as
agency of high frequency oscillatory energy.
to frequency, the oscillator output being fed to
Prior systems and methods have been proposed
a pair of independent tuned circuits oli-resonance
for translating a physical displacement of a mo
bile element, such as that of a phonograph record
to approximately the same frequency relative to
the oscillator frequency, and the tuned circuits
stylus, into a corresponding voltage by utilizing io having electrically associated with them respec
high frequency oscillations. In such systems la
tive rectiiiers provided with a common output
characteristic of the oscillations, either ampli
resistor adapted to provide a resultant diiferen
tude or frequency, is varied in response to the
tial voltage corresponding to physical displace
aforesaid displacement, and a detector circuit , _ ments of a mobile electrode common »to both tuned
is used to derive from the varied oscillations the
desired corresponding voltage. One of the op
l5"
circuits.
'
'
l
"
Y
Still other objects of our invention are to im
erating disadvantages of such prior systems> has
been that the high frequency oscillations have'
undergone amplitude and/or frequency varia-`
tions at their source, or otherwise without refer
ence to the displacement of the .mobile element,
and such inadvertent and undesired variations
prove generally the simplicity and eiiiciency of
phonograph record reproduction systems, and
more especially to provide a sound record repro
" duction system which is not only reliable and
efficient in‘operation, but is free of undesired high
frequency componentsV in the detected output
have been detected, thereby adversely affecting
voltage.
`
the resultant detected voltage. For example; mi
Still other features will bestrbe understood by
crophonics, or ballistics, in the oscillator` tube of §55@ reference to the following description, taken in
such prior systems have tended to affect the `de
connection with the drawing,` iniwhich we have
tected resultant voltage.
»
»
‘ ‘
indicated diagrammatically a circuit organiza
It is one of the main objects of our present in
tion whereby our invention may be carried into
vention to provide a method of, and system for,
_effect
-
balancingr out
amplitude
and/or
f-requency f
changes the existence of which in the high fre
quency oscillatory energy is independent of such
displacement of a mobile element into a resultant
iden-tical rectiñer circuits whereby undesired vari
Y
r
Fig. 2 shows the ideal resonance curve of each
rectifier input circuit, and a graphical analysis
`Í~ of the operation of the system.
Referring now to the system shown in Fig. l,
the tube I is the oscillator tube and may be of
» 'sof `oscillator tube.
ations in the oscillations are balanced out in the ,
Another important object of oui1 invention is
to provide a novel method of,” and system for,v
‘
any» well known type, as for example a triode.
Our invention is not limited to any specific type
and then applying the oscillations to substantially i
derived from the rectiñer circuits as a resultan-t
'
embodying the invention,
voltage by producing high frequency oscillations,
dilferential voltage.
v In the drawing:
Fig. 1 shows the circuit diagram of a syste
energy being subjected to variation in response
to a physical displacement of a mobile element.~
Another important object of our invention is
to provide a method of translating the-physical
common output of the rectifiers, while adesired
variation produced by displacement of the mobile
element in a characteristic of the oscillations is
5
The electron emitter or cath
ode 2 is grounded, while> the plate or anode 4 is
connected to the -l-B terminal of the direct cur
rent energizing source (not shown) over a series
path consisting >of coil 5, coupling link or coil s
4x5-’tand coupling link or coil 1. Coils 6 and 7 may
each have a single turny but proper coupling to
their respective secondaries (described below) is
the prime consideration. Each of inductances or
reproducing sound records, wherein vhigh 4fre
coils- 5,_ 6` and 1. is preferably electrostatically.
quency oscillations arexappliedrto substantially ¿g5-shielded _from the other to eliminate capacity cou
similar rectifier circuits employed insound re
pling therebetween. The dotted rectangles 5',
6' and 'l' represent shielding devices of any suit
to provide output voltages lof opposite polarity- able form. The condenser 8 shunts the plate
and having separate input circuits normally tuned 5 f _end
`
of coil 5 to ground, Whereas condenser 9 by
production, lthe rectifier circuits being connected
to a common frequency which’diiïers to a prede
55" passes the lower end of inductance 1 to ground
2,404,026
3
for radio frequency currents. The condenser 8
is given a magnitude to tune the plate circuit of
the oscillator tube to the normal or operating
4
ample, the push-pull condenser construction
shown by A. Badmaieñ in his application Serial
No. 490,614, filed June l2, 1943, granted March
13, 1945, as U. S. Patent No. 2,371,373, may be
frequency of the oscillator. That is, condenser
8 tunes the series combination of coils 5, 6 and ‘I 5 utilized as our condensers 21-23 with a common
mobile electrode. It is to?be clearly understood,
to the frequency of piezo-electric crystal I I.
The control grid 3 of oscillator tube I is con
nected to the high potential electrode Iii of crystal
II. The low potential electrode I3 is connected
to ground. The grid resistor Iâ is connected
in addition, that in place of using a record stylus .
30 to displace common electrode 29, there may
be employed, as for example in a microphone,
any other device which will respond to a force
to be indicated by displacing the electrode 29.
from grid 3 to ground, and provides a means for
biasing the grid 3 negatively by virtue of grid
In general, the mobile element 29 may be em
bodied in any transducer.
current flow through the resistor. As already
The oscillatory energy introduced into tuned
indicated, crystal II is tuned to the aforesaid
operating frequency to which the plate circuit 15 rectiñer input circuits Il-E'I and 2-§~-2â by the
separate coupling elements 6 and ‘i is varied in
resonates. The crystal II may be provided with
amplitude in response to the variations in ca
separate metal electrodes or metallic »coatings
pacity of condensers 2ï and 26. Normally the
functioning as electrodes. This is a familiar and
oscillator frequency is of such a value that it falls
well known form of crystal oscillator circuit, and
produces relatively constant amplitude waves of 20 at a point approximately 70% of the peak reso
the fixed frequency of crystal II. By way of
nant vo-ltage of tuned circuits ilk-21 and 22E-23.
Hence, if the oscillator frequency is 18 mc., the
example, it may be assumed that the constants
normal resonant frequency of the rectifier input
of the oscillator circuits are chosen to provide a
circuits may readily be calculated from the rela
frequency of 18 megacycles (rnc). Of course, the
invention is in no way restricted to any particular 25 tion shown in Fig. 2. Here the solid line single
peak resonance curve a'. is ideally assumed to be
requency, nor to any particular type of oscillator
that of each of input circuits i'i--Z‘I and 23-28.
circuit.
'
~
The fixed-frequency oscillations are introduced
It is obvious that if the mobile electrode 29 is
instantaneously moved towards the stator of con
into a pair of rectifier circuits. The rectiflers
may be of any well known form and are shown, 80 denser 21 the capacity of the latter will increase,
by way of specific example, as ofthe diode type.
while the capacity of condenser 23 will concur
rently decrease. This means that the frequency
Diodes I5 and I6 are connected in the manner
shown. Diode I 5 is provided with a resonant
of circuits I'I--Z'I will. be decreased. while that
input circuit including coil Il magnetically cou
of circuit 23-28 will be correspondingly in
pled to coupling link 6. The latter is included 85 creased. The opposing frequency shifts or devia
with coil I'I within the shielding means 6’. The
tions of the two input circuits will, of course.
correspond to the stylus motion through the
diode anode I 8 is connected to the high alternat
ing potential end of coil ITI, while the opposite
record groove. The sound record is not shown
end of the latter is grounded. The cathode I9
since those skilled in the art of sound reproduc~
of diode I5 is connected back to ground through
ing are well acquainted with the technique of
reproducing sound from records.
series-connected resistors 2i! and ZI. The cath
Opposite detuning of the respective rectifier
ode end of resistor 20 is bypassed to ground for
radio frequency currents by condenser 22.
input circuits relative to the normal or peak
The diode I5 has its cathode 22’ connected to
resonant frequency of curve o of Fig. 2 causes the
the high alternating potential end of coil 23. The 45 oscillator voltage injected or induced in them
to vary oppositely in amplitude andl consequently
grounded end of coil 23 is connected in common
to the grounded end of coil I 1. Coils 'I and 23
develops a variable voltage across the common
are magnetically coupled, as in the case of coils
load resistor 2I. The variable voltage is repre
G and I7, and are housed Within the shielding
50 sentative of the original sounds which were trans
means 'I'. The anode 24 of diode I6 is connected
lated into groove variations on the record.
to the junction of resistors 2G and 2l through a
The functioning of the system will now be
resistor 25. Condenser 2% bypasses the anode
more fully explained, special reference being made
end of resistor 25 to ground for radio frequency
to the curves of Fig. 2. In the latter “frequency”
currents. The coils I'I and 23 are each tuned to
as the abscissa is plotted against “amplitude” es
the same normal frequency by shunt condensers 55 the ordinate` The solid line curveV a is the nor
2l' and 28 respectively. The condensers 21 and
mal resonance curve of each rectifier input cir
28 have a common electrode which is connected
cuit, as explained previously. The point F0 on
to the grounded junction of coils I'I and 23. The
curve a shows the degree of initial mistuning or
common electrode 29 is preferably a mobile arma
off-resonance of the oscillator frequency relative
ture located normally in spaced relation between 60 to the normal frequency of the rectifier input
the respective stator electrodes of condensers 2'I
circuits. The arrangementy including the degrees
and 28. The pivoted end of the armature 29 is
of coupling of coils 6 and 'I to their respective
grounded, and the free end of the armature is,
secondaries, is such that with armature 29 in its
as shown, provided with a stylus or needle 30.
05 normal position the same amplitude of induced
The stylus 30 is ofY any desired form, and is
oscillatory voltage will be developed in the re
adapted to ride along the grooves of` a record in
spective rectifier input circuits. Under these con`
known manner. In this way the mechanical
ditions, the rectiñers will develop across resistor
variations of the record are translated into cor
2I equal rectified voltages, the voltages developed
responding physical displacements of the com
mon electrode 29. The condensers 21 and 28 are
70 by each of the rectiñers across resistor 2| being
proportional to the amplitude of the high fre
accordingly varied in corresponding fashion, but
in push-pull or opposing relation. Any desired
to
quency
the fact
oscillatory
that resistor
energy in2|itshas
input
its circuit.
ungrounded
` or well known form of push-pull condenser may
be employed for condensers 21 and 28. For ex
end connected to unlike electrodes of said diodes,
it follows that the ungrounded end of the resistor
2,404, 026
5
6
2I will Abe at zero potential due to cancellation
provide a system of record reproduction wherein
of the opposing rectiñed voltages. Hence, in the
identical changes in oscillatory high frequency
median or normal position of mo-bile electrode 29
energy are applied to identical rectifier circuits.
and derive therefrom the rectiñcation products
in opposition. Accordingly, such changes in oscil
latory energy, whether of amplitude or of fre
the succeeding audio frequency amplifier (not
shown) derives no voltage from the ungrounded
end of resistor 2l. Condenser 3| is an audio fre
quency coupling condenser. Resistors 20 and 25
act as loading elements to determine the “Q” of
the respective rectifier input circuits.
quency, balance out. However, the pickup device.
or more generally the common tum‘ng adjustment
They
device, causes opposite changes in the two identi
cal rectifier circuits thereby providing a resultant
further prevent a short circuit on each coil I1, 23
by the other and its respective diodes.
Let it now be assumed that mobile electrode 29
is shifted towards the stator of `condenser 21. At
that instant the frequency of circuit I1-21 is
decreased since condenser 21 has its capacity in»
creased, while the frequency of circuit '23»-28 is
increased since condenser 28 has its capacity de
creased. The dash line curve b in Fig. 2 repre
sents the instantaneous shift in the resonance
curve of circuit I1-21 due to the decrease in
resonant frequency of circuit I1-21. The dot
differential component of rectified voltage. From
a generic viewpoint the input network of the
rectifiers comprises a pair of reactances of like
reactive sign (coils I 1 and 23 being of like reactive
sign), and each ,of the .pair of reactances is tuned
by a respective reactance of opposite reactive sign
(condensers 21. 29 and 29, 28 are of opposite re
active’sign relative to their respective coils I1
and 23).
20
Although our invention lends itself readily to
use of a crystal-controlled oscillator, and we pre
and dash line curve c represents the instantane
ous shift in the resonance curve of circuit 23~---28
fer to employ such an oscillator, the crystal Il
due to the increase in resonant frequency of the
latter circuit. The oscillator frequency Fo (asN
sumed to be 18 mc.) has not changed during the
shift in the position of electrode 29.
the aforesaid balancing action as to changes in
oscillator frequency can be relied upon to alford
satisfactory operation, even in the absence of
Hence, points d andre Aindicate the respective
adapted for use with laterally-cut records or “hill
can, if desired, be dispensed with, inasmuch as
crystal control. lFurther, the invention is readily
locations on shifted curves b and c of the oscil
and dale” records. i
lator frequency Fo. VThere will now be induced a 30
While we have indicated and described a sys
tem for carrying our invention into effect, it will
be apparent to one skilled in the art thatour in
vention is by n0 means limited to the particular
organization shown and described, but that many
greater amplitude of oscillatory voltage in circuit
I1-21 than in circuit 2x3-28, as is readily >olo
served from Fig. 2 because point d exceeds point
e in amplitude. Hence, the ungrounded end of
resistor 2l will be at a positive potential relative
to ground, and the potential will be of a magni
tude `depending upon the algebraic s_um of the
rectified voltages. In ,other words, the rectified
voltages are differentially combined to produce a
modifications may be made without departing
from the scope of our invention.
What we claim is:
l. A method which includes the steps of gen
erating high frequency oscillations of a predeter
resultant voltage proportional to the difference
between the amplitudes of oscillatory voltages
induced in the rectifier input circuits. By operat
ing normally at the steepest point lon the slope
tively small frequency value from said oscillation
of the resonance curve
frequency, separately rectifying voltages induced
the resultant rectified
mined frequency,> introducing said oscillations
into a pair of resonant circuits tuned to a com
mon frequency differing by a predetermined rela
voltage will. be of maximum values for varying 45 in each of said tuned circuits, combining in po
larity opposition the rectified voltage resulting in
frequency deviations of the rectifier input circuits.
The 70% olî-resonance point Fo is such a steep
each of said rectification steps, and concurrently
varying in opposite senses the frequency of each
point, and is also a point of the curve where
greatest linearity exists.
of said tuned circuits in response to displacements
,
Where the displacement of mobile electrode 29 60 of a mobile element.
is relatively slow.
in response to miscellaneous
2. In combination, a pair of rectifiers having
physical changes, the resultant rectified voltage
a common output resistor, a separate tuned input
across resisto-r 2| may be utilized in any desired
circuit connected to each rectifier, means for
tuning said separate input circuits to a common
manner. For example, the ,voltage may be
visually indicated in a measuring device, or it may 55 predetermined high frequency, said means in
cluding a common mobile element whereby the
be employed to operate a correction or work cir
frequencies of said input circuits may be con
cuit as in control circuits. ,
currently varied in opposite senses, and means
Any undesired frequency modulation effects or
for applying in substantially identical manner to
amplitude modulation effects, arising otherwise
said input circuits high frequency oscillations of
than by movementv of armature 29, which may
a frequency substantially different from the
develop in the oscillatory energy induced in the
common predetermined frequency of said input
rectifier input circuits I1-21 and 23-28 will
circuits.
balance out across resistor 2 I. The balancing out
3. In combination, apair of rectiñers having
of such undesired amplitude variations or fre
quency variations takes place by virtue of the fact 65 a common output resistor, a separate tuned input
circuit connected to each rectifier, means for tun
that output resistor 2I is in push-pull relationtc
ingsaid separate input circuits to a common pre
rectiñers l5 and I6. It will Vbe obvious that any
change in amplitude and/or frequency of the
determined high frequency, said means including
a common adjustable element whereby the fre
oscillatory energy applied to coils I1 and 23, not
due to movement of armature 29, will have the 70 quencies of said input circuits may be concur
rently varied in opposite senses, means for apply
same effect at the two rectiñers. Hence, the
rectification products of these effects will cancel
ing in substantially identical manner to said input
out across resistor 2|. Our system is, therefore,
circuits high frequency oscillations of a frequency
non-sensitive to microphonics, or ballistics, in the
substantially different from the common prede
oscillator tube I. From a generic viewpoint we 75 termined frequency of said input circuits, and
2,404,026
7
means for accurately maintaining said high fre
quency oscillations at said different frequency.y
4. In combination, a pair of rectifiers having
a common output resistor, a separate tuned input
circuit connected to ’each rectifier, means for
tuning said separate input circuits to a common
9. In combinatioma pair of rectiñers having
a common output resistor, a separate tunedinput
circuit connected to each rectifier, a separate
condenser for tuning each input circuit to a com
mon predetermined high frequency, said con
densers including a common mobile electrode
whereby the frequencies of said input circuits
predetermined high frequency, said means in
may be concurrently varied in opposite senses,
cluding' a common mobile element whereby the
a crystal-controlled oscillator for applying in sub
frequencies of said input circuits may be concur
rently varied in opposite senses, means for apply ll) stantially identical manner to said input circuits
high frequency oscillations of a frequency sub
ing in substantially identical manner to said input
stantially different from said commen frequency
circuits high frequency oscillations of a frequency
of said input circuits, and a record stylus opera
substantially different from said common fre
tively associated with the mobile electrode to
quency of said input circuits, and said mobile
produce physical displacements of the latter in
element including a phonograph record stylus
response to groove variations of a sound record.
adapted to vary said mobile element in response
10„In combination with a crystal-controlled
to groove modulations of a sound record. .
high frequency oscillator including a pair of
5. In combination with a crystal-controlled
series-arranged output elements, pair of recti
high frequency oscillator including a pair of sepa
rately shielded output elements, a Pair of recti 20 ñers each having its respective resonant input
circuit, each of said input circuits being reactively
fiers each having its respective resonant input
circuit, each of said input circuits being reac
tively coupled to a respective one of said output
elements, said input circuits including a pair of
resonating condensers of the type. provided with
a common mobile electrode, and a common output
resistor connected in the space current paths of
said rectiiiers, said rectiñers being arranged in
polarity opposition.
1
6. A method which includes the steps of gen
erating high frequency oscillations of a predeter
mined. frequency, inducing in response to said
oscillations at least two resonant currents of a
common frequency differing by a predetermined
relatively small frequency value from said prede
termined oscillation frequency, separately recti
fying said induced currents, combining in polarity
opposition the rectified voltage resulting in each
of said separate rectification steps, and concur
coupled to a respective one of said output elements,
said input circuits including a pair of resonating
condensers of the type provided with a common
mobile electrode, a common output resistor con
nected in the space current paths of said recti
ñers. said rectiñers being arranged in polarity
opposition, and sound-responsive means for actu
ating said mobile electrode.
11. In a system for translating sound-repre
sentative modulations into sound Wave currents,
a source of high frequency oscillations, a pair of
rectiiiers having separate input circuits, reactive
means common to said input circuits for tuning
the latter to a like predetermined frequency dif
fering by a relatively small frequency value from
the normal source frequency, means common to
the rectiiiers for combining the rectified outputs
thereof in polarity opposition thereby to provide
rently varying in opposite senses the frequency 40 said sound currents, and said reactive means in
cluding a transducer device for varying the fre
of each cf the induced currents.
o_uencies of said input circuits in opposite senses
7, In combination, a pair of diode rectifiers
relative to said source frequency.
having a common output resistor, a separate
12. In a system for indicating physical dis
tuned input circuit connected to each rectifier,
placements of a mobile element, a source of high
means for tuningY said separate input circuits to
frequency oscillations vof a predetermined fre
a common predetermined high frequency, said
quency, a rectifier system provided with an out
means including a pair of condensers having a
put resistor, a network for providing amplitude
common adjustable element whereby the frequen
modulation of said oscillations in accordance with
cies of said input circuits maybe concurrently
displacements of said mobile element, said last
varied in opposite senses, and means for applying
network comprising a pair of reactances of like
in substantially identical manner to said input
circuits high frequency oscillations of a frequency
reactive sign, each of said reactancesbeing tuned
by a respective reactance of opposite reactive sign
substantially diñerent from said common prede
to said predetermined frequency, said mobile ele
termined frequency of said input circuits.
ment being operatively associated with said last
8. In combination, a pair of rectiñers having
respective reactances for concurrently varying in
a common output resistor, a separate tuned input
opposite senses the magnitudes thereof, means
circuit connected to each rectifier, means for tun
ing said separate input circuits to a common pre
applying said oscillations to said network, said
rectifier system comprising a pair of rectiñers
determined high frequency, said means including
connected in polarity opposition, each rectifier
a pair of condensers having a common mobile
electrode whereby the frequencies of said input
circuits may be concurrently varied in opposite
senses, means for applying in substantially iden
tical manner to said input circuits high frequency
oscillations of a frequency substantially different
from said common predetermined frequency of
said input circuits, and a piezo-electric crystal
device for accuratelymaintaining said high fre
quency oscillations at said differentfrequency.
being connected in a closed circuit with a respec
tive one of said like reactances and said output
resistor, and means applying the modulated oscil
lation output of said network to said rectifier sys
. tem thereby to develop across said output resistor
-‘a’ voltage representative of said physical dis
placements.
y
JOSEPH G.y BEARD.
ROBERT W. HARRALSON.
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