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Патент USA US2404137

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July 15» 19,46»
'
` J. A. MÀURERCJR' v
METHOD OF AND MEANS- FOR RECORDING ELECTRICAL
’ 2,404,137
IMPULSES AND IMPULSE RECORD PRODUCED THEREBY
'
Filed Aug. 4, 1944
A
4 Sheets--Shee'ri l
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INVEN'TOR:
JOHN A.MAURER JR.
AGENT
'July 16, 1946.METHOD OF AND
, JQ A» MAURER, JRv
MEANS FOR RECORDING ELECTRICAL' 2,404,1 3_7
IMPULSES AND IMPULSE RECORD PRODUCED THEREBY
Filed Aug. 4, 1944
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4 Sheets-Sheet 2
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INVENTOR:
JOHN A. MAURERJR
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AGENT
July 16, 1946.
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lJ. A;-.MA'URl-:R JR -
OF AND MEANS
FOR REGÓRDIN
`
s AND IMPULSE RECORD PRO
Filed
2,404,137 ~
ELECTRICAL
En THEREBY
Aug. 4.4 1944
4 Sheets-Sheet 3
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INVENTOR.'
„JOHN AMAURER JR.
BY@ Maw/„1%
AGENT
'
J. A@ MAURER, JR
16’ 1946METHOD OF'AND MEANS FOR RECORDING ELECTRICAL
2,404,l 37
IMPULsEs A_ND IMPULSE RECORD PRODUCED THEREBY'
Filed Aug." 4', 1944
4 Sheets-Sheet 4`
INVENTOR;
v
JOHN A, MAURERJR
BY@ mm
'
AGENT
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2,404,137
Patented July 16, h1946
UNITED STATES PATENT fori-fica] l
' 2,404,137
METHOD OF
-
FOR RECORDING
'ELECTRICAL IIWPULSES l.AND
IMPULSE
RECORD PRODUCED THEREBY
John A. Maurer, Jr., New York, _N. Y., assignor to
J. A. Maurer, Ine., New York, N. Y., a corpora.- ‘
tion of New York
Application August 4, 1944, Serial No. 548,098
15 claims.
(o1. 17e-fiona) l
.
cording of electrical impulses on a moving ñlm
»as it is practiced, for example, in sound-on-ñlm
recording.
By such recording, two main kinds of photo
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photocells employed therein. 'I'he individual re
sponses of the photocells hence may be non
This invention relates to the photographic re- i
linearly related to the amplitude of the electrical
impulses recorded inthe push-pull class A tracks,
5 as loingA as their ,difference is linearly related to
that amplitude. Consequently,no amplitude dis
graphic tracks may be produced on the moving
tortion occurswl'ien the push-pull class A tracks
are so produced that the two component _half
tracks of their prints have eachv a transparent
` nim, namely, variable area tracks and variable
density tracks. Among the means devised for
their production, certain optical systems of the
mirror oscillograph type lend themselves equally 10 portion, or light transmission,A which is non-lin
early related to the aforementioned amplitude if
well to the production of both kinds of tracks.
only the difference of_ the two transparent por
In these optical systems, a mirror mounted for
tions, or light transmissions, is linearly related
vibration on an oscillograph galvanometer isom
ployed for varying the lightflux at the recording
thereto. VLSuc/_h a linear relationship»4 is estab
point, that is, the point at which the optical axis 15 lished, >_ according to (the. invention, when the
transparent< portion,l or- ligiht transmission, of
of the system strikes the film. TheL invention is
each half-tracker; the print varies in proportion
concerned with optical systems of the mirror oscil
to .the square ofthe amplitude referred'to above.
lograph type, and considers thel production of
At the same time, alvariation of this character
.both-»variable area and variable density tracks
therewith.
Y
>
More particularly, the invention is related to
the production of'variable area and ‘variable den
sity tracks which are composed of two half-tracks
¿int juxtaposition.v Each half-track is a, complete
record of the electrical impulses, but-the Vtwo
Yhalf-tracks are displaced `180° out of phase in
«relation to one another transversely of the film;
:This kind of track is known in the art as a push
pull class A track;
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`2() brings it about that the value Èof the transparent
portion, or light transmission, for the> rest posi
tion of the oscillograph mirror decreases to such
Ya degree that the ground noise is materially re
duced when» sound is reproduced from the print.
:'25 VThe invention, furthermore, provides the‘fol
lowingv methodv for >recording push-pullclas's'A
ïtracks from which prints may be madewith half
tracks -hai'fimgthe properties outlined at the end
of the preceding paragrapiùl
A
'I'he advantages of push-pull class A tracks are " 30
well known, and hence need not be stated here
anew. It is likewise known that, for the rest
position of the Voscillograph mirror, prints made
of these tracks ordinarily have a 'comparatively
Widetransparent portion in the caseof variable
area tracks, and a comparatively large light
transmission lin the` case cf variable density
tracks. Thiscondition is unsatisfactory when
I '35,
Y ` 1
, l
. `
YA nlm is möfed vertically' pastj the recording
point at ’whichV two horizontal lines of light are
produced in juxtaposition. The amount of'lig'ht
flux contained in each line of ‘light is contin
uously 'varied in proportion to the square of the
yamplitude of the electrical impulses to be record
ed, but the amount of light ilux containedV in
-the one line of light is varied 180° outof _phase
in relation to the amount of ylight `flux contained
in the other line of light. >When. therv'ariation .y
.sound currents so that sound is to be reproduced :40 of the two amounts of light iiux is accomplished
by varyingV the length of the two linesof, light,
-from the prints, forit lthen‘results in a compara
a variable area track is'frecorded, and when it
tively Alarge amountrof ground noise. It is, of
>is accomplished :by varying their intensity; a var
course, possible to employ, in the production of
' the electrical impulses recorded in the tracks are
iable densityy track is recorded. ’ f
push-pull class A tracks, the well known electri
cal methods of ground noise reduction, be it the 145 The> invention also proposes means Vforfcarry
ing. out this method. In an optical system o1'
bias, or the shutter, method. But the application
the mirror oscillo'graph type', a, screen is provided
of either method presents certain dìñlcultiesand,
with a pair of uniformly illuminated openings,
y,in addition; requires special equipment such as
>images of which are formed in the plane of a hori
rectiñers and the like.
'
„ The invention,~ therefore, proposes a. method of, 15‘0 .zontal' slit so as to be movable by the 'vibration' of y
theoscillograph mirron» The twoV openingsI 'are
and means for, producing push-pull class A tracks
in-which groundnoise reduction is inherent. _Its
starting point is the fact that the response of
substantially Vvtriangular and- alike. fTlíey‘ >are
'spaced .apart horizontally, and inversely», posi
tioned‘vertically’in that-„the- tip of the oneopen
,any conventional push-pull-rreproducing system
¿isequal to the difference in` response of Áthe tw@ est 'ing "1s-¿ifa alignment Y Withïthe base of! the einer
2,404,137
3
opening, and vice versa. TheV shape of these
openings is such that their effective horizontal
extension or width, increases in proportion to the
square of its distance from their tip. A variation
in width of this character is obtained by provid
ing each opening with >one or two .edges jwhich ex
ferred embodiments thereof, and its scope will be `
pointed out in the appended claims.
In the drawings:
Fig. 1 is a diagrammatic perspective view of a
variable area recording optical system in which
the invention has been embodied.
tend from its .tip towards its base, and. whose ef- ‘
Fig.-2 Yshows anl enlarged elevation ofva part
of the optical system of Fig. 1, namely, a screen
fective contour is parabolic. The parabolic edges
preferably have their vertex at the tip of the
opening, and their axis parallel to its base.
.provided with a pair of openings according to the
' Since the edges are parabolic throughout their
y Fig. 3, which'is drawn toa somewhat larger
eiîective contour, the transition between any two
'scalethan'ïFig 2. shows the openings of Fig. 2
points thereon is a smooth one. For that reason,
related to a system of rectangular co-ordinates.
invention.
.
Fig. 4- is adiagrammatic representation of a
part in the variationof the light `iiux‘at the re l5 «print 'made from »a push-pull class A variable
area- track produced by means of the openings of
cording point, the use of a pair of these openings
, and also because each opening continuously ,takes A v
in the optical system introduces no higher order , `
harmonic. ,
,
Fig. 2.
Figs. 5,6, 7, and 8, show in enlarged elevation
The ground noise reduction effectedY by the 'i modiíications of the openings which may be pro
method and means of -the present invention 20 vided in the screen of Fig. 2.
.Fig.„9,. V.which 'isy drawn to .a somewhat larger
amounts to 3 decibelsV inthe casel of» variable
scale thanFig. 8, shows the openings ofFig. 8
area tracks,'and~6 decibels
the case of variable
related toasystem of rectangular co-ordinates.
density-tracks. These resultsare- sufûcient to
Fig. 10 is a diagrammaticy representation of a
make the »application ofthe electrical methods of
groundY noise~reduction Vsuperfluous in a great 25 printV made from a push-pulll class. A variable
area track ,produced by means >of the openings of
number of practical cases. « The production of
Fig. 8.
push-pull `classA sound tracks with ground noise
reduction >hence is materially facilitated by the
invention since its application requires neither
special equipment, nor critical adjustment.
ce
< It Ashould be noted that the terms “vertica”
which the invention. has beenembodied.
.
Fig. 12 is a diagrammatic longitudinal section
and “horizontal” have >been -us'ed in the foregoing
brief summary of the invention, and will be used
of theA optical system shown in Fig. 11',_ theoptical
throughout this specification, not in any absolute
oscillograph mirror as an aperture. .
sense but merely as indicating two directions at
axis being represented asa straight line and an
zontal
tween these terms «has Ybeen determined solely by
convenience in 'description »and illustration.
Anvobject of the invention is the provision‘of
improvedpush-pull class A tracks.
Another V_object'of the invention'is the provision."l
-of push-pullA -classA sound tracks with inherent
ground noise reduction.
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ist » Fig'- _1‘3 is acorr'esponding section in the :hori
rightÍ angles to ¿each other, andthat choice be
t
,
Fig. 11 is a diagrammatic perspective view of
a variable density recording optical system in
‘
3 Another'object of the invention is the provision
of'push-pull class A variable area tracks having
'half-tracks whoseY transparent portion varies in
' >’proportion to‘thesquare'of the amplitude of the
plane.
,
.
.
.
.
.
Fig. 14 is an enlargedfront elevationof a part
of the optical system4 ofA Fig. 11.
1
„ îFigï. 15 is a diagrammatic representation of a
print made from a push-pull class A Yvariable
»density track produced by means of any/of the
pairs lof openings shown in Figs. 2 and _5 to 8, and
Figs.. 16 Aand 17 show adaptations to a particu
lar purpose of theopenings of Figs.. 2 landß, re
spectively.
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.way of example, howthe in'->
u Figgl shows, by
.ventionmay be, embodied4 in a> conventional vari
>alolerarea recording optical/system. The optical
electricalzimpulses recorded inv the tracks.
_Another object ofthe inventionV is the pro-,v50 system of Fig. 1 has a suitablelight vsource such
v‘vision of push-pull class A variable density tracks
having:V half-tracks whose.V light transmission
Y varies -in proportion to the square ofthe _ampli
tude of -the Yelectrical impulses recorded in the
'as the ñlainent .ID of anv in_candescentrlamp ||.
Lamp. iilamenît |0- isf imaged substantiallyon the
*mirror v|2 .by the> spherical 'condenser I3., and:v re
' imagedv .substantially in. the> microscope objective
|'4 by the Aspherical lens. 'I 5'.
tracks.
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Another c object yof
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Another object` of the invention is to provide a
4_rnlîitliool 1_ of producing. push-pull class A sound
vtrackswith ground noise reduction which does
not require special equipment.
`
A
` Another object of the invention is'the pro
vision of improved means for producing push
.pull ,class A sound tracks with inherenty ground
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f
triangular'openings 2| and 22, and placed adja
cent to condenser lensï|3 so that openings 2 |l and
22.1are uniformly illuminated by lightfflux> from
lamplñlame'nt I0. Openings 2| and 22, which'
Yare spaced apart horizontally, are alike but in
versely positioned verticallyin that the tip ofthe
one‘opening Vis in alignmentiwith 'the base ofthe
other opening, and vice versa.V -The particular
Vshape of openings 2|- and '.22 -wi'll be -explained ~
hereinafter.
noise,reduction.y
.
the invention is to provide ‘,455 ' A. screen y2|) is. provided-with two substantially
an improved method of producing push-pull class
'_A tracks.
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`.Another object of the invention is the pro
vision of such means which introduce no higher
order harmonic. v f `
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'Asphericalslens 23 is placed-- in frontlof mirror
I2 and formson a screen 24 two images >25 and
’26 yof.openings 2| and 22;'"1j-'espectively.`V .'Since
Stilljothe'r objects and advantages cf the in- , . openings 2| and 22 are‘un-iformlyî illuminated,
ventiorrjinclude'4 those which are hereinafter
ystateo'lfor apparent, or which are incidental tothe
invention.
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, .'I'hejinvention- will be better understood when
the( following description. is considered f' with `the ,
accompanying drawings of certain presently pre frs
and since lens 23 lis spherical, images 25 and 26
are' 'two >uniformly ¿illuminated 'light spotsA whose
ïshape'- and relative position are'thoseA of 'openings
`
£404,137
2G thus -are formed inthe plane of slit'21 so as’ to
illuminate two portions thereof. A»As seen from
the recording point 30, therefore, there appear at
slit 21 two horizontal' lines of light in juxtaposi
tionk which are reproduced at recording point 30
by the microscope objective I4. Recording point
3U. is thepoint at which'the' optical axis of the
system strikes the iilm 3|, and film 3I moves at
recording p_oint.> 3E!A in a substantially ivertical di-V
rection as indicated by the arrow 32. - '
6
axis a‘pa?anei rebase-4|. :Edge ¿6,1m theether
hand, extends fromtip W towardszbaseï45 'and is
a segment .of the parabola,l openingito‘ the- left',
which hasl‘its lvertex at W andl its axis bfparallel
to bas'e .'45.' Since the two parabolae areequal,
and since edges 4U and 44 both are‘of'the length
2h, bases 4I and45 are also of equal length (w).
Openings 2| and 22 thus are alike, but inversely
positioned vertically. in that the tip ofthe one'
10 opening is'in alignment with the base Tof the -other
opening, and vice versa.
Mirror I2 is mounted for vibration on an oscil
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A speciiic property of openings 2| -and 22 which
lograph galvanometer 33, or similar device'for
results from their. being bounded by-«paarabolic
translating electrical‘impulses into mechanical
edges 42 and 46, respectively, will now-be` ex
vibrations. The _axis 34--,-34 about which mirror
I2 is` adapted to vibrate, extends horizontally. 15 plained with referenceto Fig. 3. In this figure,
which is drawn to .a somewhat larger scalethan
When-_ therefore, the electrical impulses to be
Fig. 2, openings 2| and `22 are related tQas-ystem
of rectangular co-ordinates X-X Vand `iff-Y'.
oscillograph 33, mirrorA I2 vibrates in accordance
',I‘he origin-O of this co-ordinate `system ,isthe
therewith and thereby moves images 25 and 26
vertically across >the, horizontal slit 21. This 20 center of the rectangle formed by the two `straight
edges 40 and 44, and the two extensionspf--bases
movement of images 25 and 26 ïbrings itabout
4I and 45, respectively, between edges 40 and 414.
that each of the two lines of light appearing at
The axis'X-X of the- system is parallel to bases
slit 21, and again at recording> point 30, continu
4I and 45, and its axis Y-,-Y parallel to edges 40
ously varies in» horizontalA extension, orlength,
in accordance with the amplitude of the electrical 25
Since the length of edges 40 and 44 is V‘2h and
impulses applied to‘o’scillograph 33. . I . g
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_
that of the two extensions of bases 4I and 45 is
Thus„.there is produced on nlm 3l as it _moves
2d, the co-ordinates of the tips V and W of open
vertically past recording point 30, a photographic
ings 2I and 22, respectively, are (d, h) and> (-d,
record of the electrical impulses which <arefap»
plied> to the' oscillograph 33. vThis record is made 30 -h'), respectively. u,Curved-edge I»42 _thus is -a seg
recorded are applied _in known manner to the
'and
44.
Y
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L
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ment of the parabolalwhose equation is .
_up ofthe two variable area tracks35 and 36 in
juxtaposition and, sincel the variation in length
(i)
Ílçc'y-,mëm-a'
j
_
,
ofthe two lines of light at recording 'point 30 is
vançhcurvedl edge 46 a segment ofttheîparabola
continuous, each track `35and3îi -is a complete
Y
z l «- ‘
.record of the electrical impulses.. However, on 35 „when equation 1S _
account of the inverted'ïposition `of openings _2_I
{2i-bi1.
-Ic_<-yL+h)'2`=-'<r+d>
» >
and 22, track 36 is displaced y180° out of phasein
.
j
IIn
the
above
equations,
k
is
a
factorof
propor
relation to track 35 transversely of film l,3.Iï.
tionality whose choice governs the relation of the
Tracks 35 and 35 henceare thel two component
_length'w of bases 4Il and' 45 to the length 2h of'
half-tracks of'a push-pull class A variable -area
edges 40'and 44.
trackl 31. But track 31 is different from,l and
>Referring further to Fig. 3, aline l'is drawn
superior to,l a conventional variable area trackv of ` parallel'to bases .4 I` and 45.,- Line'Z traverses open
the push-pull class A type- forv the following
`ings 2| and.22 so that segments AB andA CD are
,determined
'on it »by edges 4I)r and 42 and- edges
Referring. for the sake of further explanation
reasons.v
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to Fig. 2, there is shown an 'enlarged elevation of i
the screen 2'!) with the two substantially triangular
openings 2| and 22.> Opening >2I1hastwov straight
edges 40 and 4I which areat right angles to Vone
.43.’vand 44,’respectively. Fig. 3 also _shows that,
r.with respectt to‘ Equationsl _and 2,"AB. equals
:r-dÍfor-fa' given V.value of y and CD V‘equals
another, and. acurved edge` 42 opposite theiright
angle formed by edges "43 and 4I".` Correspond'
ingly, opening 22 has two straight edges'44‘ and
¿fix-Hl) for. the same value of y. According to
,Equation 11,' therefore,
-ï
45 which are at rig-ht angles to one another, and
a curved edge >46 opposite the right angle formed
lby edges 44 and 45. The particular manner` 'in 755
which edges 42` and 45 are curved, will be‘de
scribed presently.
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Openings 2l and22 are spaced apart horizon]
tally so as tobe separated by a distancej2d,‘at
which distance straight edge 40 of opening 2'I‘and
straight edge 44-of opening 22 are parallel to'one
another, Straight edges 4I and 45 of'y openings
2l and 22, respectively, lare also parallel to one
Y'
difference of the two segments AB and
y,one line lthus is a linear function `of y, andr this
`fact bears upon the operation of the opticalsys
tem of Fig.,1 as follows:
f As has been` pointed .out
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.
hereinabove, , the
-images 25 and 26 formed in the plane of slit'21
are two uniformly4 illuminated light spots whose
another, the distance between. edges `‘4I 'and 45
beingl equal to the length 2h of edges 40 and 44. 565 shape and relative position are those of openings
2I _and 22,. Furthermore, screen 20 is adjusted
Assuming that straight edges 4I and 45 are the
so that bases 4I and 4,5 of openings 2l andf22,
bases of openings 2| and 22, respectively, the tip
respectively,4 extend horizontally,` that is,~ _inîthe
V of opening 2I thus is in alignment with the
same direction as mirror axis 349-34 andfslit 21.
base 45 of opening 22, while the _tip `W of Opening
-For thisy adjustment of screen 20, lineïil of
4'3
22 is in alignment with the base 4I of opening> 2 I.
Curved edges 42 and 43, ñnally, aresegments
of two parabolae which are equal, but'differently
positioned. Edge 42 extends from tip V towards
indicates the horizontal line through openings 21
and 22 which is conjugate to slit 21 with respect
'to lens 23,V the position'of‘this line relative'f-to
base 4I and is a segment of the parabola, opening
to the right, which has its vertex at V and its ¿75 `inclination of mirror I2. SegmentsAB'andf‘CD
atome?
7
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8 .
-onïlineflg therefore,` represent-the >two horizontal
180°.:out of phase in relation to .enea-mother, w1
lines. of light'appearing .at slit„2f'|, and recording
point 30 fora given angleof rvibration’ofmirror
.|2.:1 Moreover, the adjustment .of mirror vI2 'is
such that at its rest, or zero,rposition, that is,
when ¿no electrical impulses'are applied to oscil
lograph 33, line Z .isV halfway between gbases '4|
. increases vwhen wz decreases> .and vice versa.
.Track '52 »may >be :reproduced with. any con
ventional push-pull reproducing system-¿Suona
system essentially includesltwo photocellsene for
eachhalf-track, which` generate voltages ¿in 'a
pu'shepull .electrical `.circuit 189° vout of. phase.
and.45..so .as tocoincide with axis X-l-X. The
term
track :'52 is ,thusv reproduced, v.a . certain
Equations 1, 2, andY 3, then `denotes the
amount of riight flux is transmitted by transpar
ent portion ’63 to the one photocell, yand another
deflection, by the vibration'of mirror |2..ab.out
its axis-34-34, of images :2:5„and =2v6xwith respect
amount of vlight flux ,byl transparent portion 64
to'slit Y2~`| in such a manner' that positive values
of :y 'indicate deflection upwards, that is, in a
sense >opposite to that indicated 'by the arrow 32,
while negative values vof vy indicate deñection f
downwards, that is, ’in the sense indicated by
arrow'32. According toüEquationsland 2, the
to the Vother photocell. , Since 4these twoV amounts
of ~Iig-ht flux are linearly related to w1 and wz, re
spectively, their difference is a 'linear function
of the amplitude referred .toV above. So isy the
response'of the entire reproducing system since it
is, as is well known‘finï the art, >equa-l _to lthe dif
length of each of the two lines of'light .at slit 21
ference in response ofthe 'two'photocells
'
and recording point `3|) thus varies in proportion
A The yelectrical impulses applied to Yoscillograph
to the square of the deflection of images 25 .and 20 33, recorded «on `film' 3|, andf printed onto film
26, respectively, and the length of the one line
5|, may thus begreproduced «Without amplitude
Varies at the same rate as, but 180° out of phase
distortion although half-tracks 35 and 36, »and
in relation to, the length of the .other line. But,
half-tracks 53` and r54', are distorted because the
according to Equation 3, the difference in length
Width of their individual modulated portions
of the two lines of light is a linear function of 25 varies in proportion to the vsquare of the ampli
the deflection of _images _25 and 26, and valso of
ithe amplitude of the electrical impulses applied
to oscillograph 33 since `the deflection of images
-25 and 23 is proportional to this amplitude.
tude of said electrical impulses.
which are opaque and vary in this manner: The
bolic edge. 'Now it will bev shown wherein the .
advantage resides of employing such 'openings
rather than the conventional openings rwhich
are bounded by three straight edges. Referring
tothat end again _to lFig. 3, it `has been pointed
out hereinabove that mirror `|2 is adjusted „so
So -far, it has been explained only thatundis
torted vreproduction of the electrical impulses re
corded with the optical system of Fig. l may beV
30
The two `variable area half-tracks 35 and 36
had ldespite the _employment therein of two
on iilm 3|, therefore, have modulated portions
openings, each -,of which is bounded by a para
difference of their horizontal extensions, or
widths, «is a linear function yof the amplitude of
the electrical impulses applied to oscillograph 33, Y
although their >individual widths vary in propor
tion to the square of that amplitude; the Width ’
of the'opaque portion ofv half-track 36 varying
at the same rate as, but V18.0° out of phase in rela
'tion'to, the width of the' opaque portionof vhalf
track
35.
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that, when itis at restVlinelcoincides with axis
40 X-X- For this position of une l, the segments ,
'
'The push-pull class A variable area trackV 3l ‘
whichis composedl of half-tracks35 and `36, may
betra'nsferred from ñlm> 3| `onto ‘another `ñlln
by printing. Such a print is‘illustrated, -by way
of example, in Fig. 4.> A ñlm 5| has printed
there’on‘the push-pull class A variable area track
5,2,which _is composed of the two 'half-tracks 53
andr 54 in îjuxtaposition. Track 52 jis'shownflike.
wise by way of example, asbeing arecord ofthe "
>full cycle of a sine-wave.
This cycle is'com
pletely recorded oneach vhalf-track 53 and 54,
but vthe two half-tracksW are fdisplaced 180°"out
of phase in relation 4to one-another; the peak 55
on half-track 53 being opposite the val1ey7560n
>AB and CD thereon become the segments A’B’
and C’D’ on axis X-X. The length of each seg
ment A’B' and C’D’ is kh2, Vwhich value is ob-`
tained by substituting O for- y in Equations l
and 2 and solving them. for m-d and _:c-‘l-d),
respectively. The differenceV in length of-segn'
ments A’B’ `and C’D’ hence Vequals zero-which
result' is also obtained by substituting O for y in
Equation 3'-and so does the difference wr-wz
when" the value of w1 and wz each becomes equiv- `
`alent to ML2. Thus, there actually is no response
from half-tracks V53 and 54 when vmirror'jlî‘is
Vat rest.
’
.
‘
'
Furthermore, the length kit? of 'segments
and CTD’ is one quarter of the length w of bases
4`| ‘and‘45' since w equals 4lch2. This result is ob
half-track 54 transversely'ßf ji‘llrnY 5|, and _the
Avalley 51 on half-track 5,3 being, inthe same
tained by Isubstituting -~h forry in Equation .l
manner, opposite the peak 58 on half-track-54.
equations for œ-d and «(‘œ-l-d), respectively.
' ' Eachfhalf-track 53 yand 54 has an'opaque` por
and -i-h for y in Equation 2 and solvingV the two
Y .Abroken line 48 is drawn from the tip V of
tion 6| and 62, respectively. anda transparent "60 opening 2| to the end point P oi.”> its base, 4|, and
portion 63 and 64, respectively. ‘Transparent por
a -broken line 49 from the tip W of ropening 22
tions 63 and 64 are modulated portions of >half-`
to the end point Q of its base 45. Lines 48 and
tracks 53 and 54, respectively. The `horizontal
extension, or width, of 'transparent' portion 63
is w1, and' that of transparent portion 64 'is wz.
As will'readily be?understood by‘ those skilled in
t 49 both are straight. There is determined, there«
fore, von axis X-X the segment A’E by edge 40
Vand line` 48, and the lsegment FD' by line 49'and
edge 44. According to elementary geometry, the
theart, w1 and wz ,are related to theamplitude
length .of segments’A'E and FD' is half the length
w of bases 4| and 45, that is, twice the length of
Athefçís'cillc')graph 33, in the same manner as the 5.750 segments A'B’ and C’D’.
The >fact that the lengthv of segments A’B'y
YWidtlfisffof the opaque portions of _halfl-.tracks .35
¿andj.3.6. 'I'hat is to say, while `w1 «and wz vary
and C'D'isY , Y
x
or the electrical impulses which. wereapplied to
-each;~in§ proportion to the squarel of that amp1i-`
¿tude,~ thei difference y1in-wz is a'. linear functionY
` thereof. § Since, »furthermore vw1 and
vary ¿75
NS
2,404,137
9Í
i
w.
2
leadsto -the following conclusionsi
'y
~_
`
edges 40 and 4| of opening! |' 'form a riglit‘an'gIe,A _
t Let,V it be'assumed that,'in the opticalrsystem
of Fig. 1, there are employed openings 2| and 22
and, alternatively, tv/o> conventional openings
and 'so do straight e'dges`84 and `85-‘of-`openingf
12. Curved edge 42 of opening 2|Üis ‘opposite
the right angle formed by'edg‘es' ‘481and 4|",‘an‘d
curved edge 86 of openingv 12 is opposite the'right'.
Which are bounded .bythe straightedgesw, 4|
and' 48, and 44, 45 and 49, respectively. _Since
the two'pairs of openings both have edges 4| and
angle formed by edges‘84 and 85:- vTheA length of -
straight edges 48 and 84 is 2h,"that" óf- straight
edges 4| and'85 is w, and .curvedîedgesr42‘andï'
45 as their bases, the maximum length Which
each 0f_ the two lines of light at slit 21 and. re
cording point`3ß may have, is the same in either
case. But, when mirror |2 is at rest, the length
of_ the two lines of light ishalf their maximum
86 are segments `of two parabolaefwhichiarerequal,
but differently'positioned.` ‘ The parabola'y ojfï'edgef
15
42, which opens tothe right,"hasmìtsîverteib-vat
V and its axis a parallel'to' baseî4'lrrsof-thatffedge
42 extends from tip V towardsQbasë’M-.î The pas;
length with the two straight-edged openings,
While it is reduced _to one quarter of that length
withvopeníngs 2| and 22. The opaque portions
of' half-tracks 35 and 36, and the transparent
portions 63 and 64, therefore, may have the
same„maximuml Width with either pair of open
ings.. ` ÍBut their Width for the rest position of mir-V
ror |2- is half -their maximum width with the
conventional pair _of openings, While it is re
duced to a quarter of that width with the pair
I0
tip V of opening 2| is iii-‘alignment >with fthexbas'e‘l
85 of opening 12 whose tip W' in its turn,'is,A infv
alignment with the base 4I of opening 219.1.' @penings 2| andl 12 thus are alike‘but inversely'posi
tioned vertically. More particularly;I> >strz‘iightL
While the length of segments A'E landli‘D' is "ï
20"
rabola of edge 8|ì’opens-l also to the .riglitpbutfhasf
its vertex at W’ and its axis-:bf paralleii‘to'ïibase'-,
85 so that edge 86 extends from tip .Wá‘"._ftoyvazrdsi>
base 85.
_
_,
__
_.
Finally, openings 2| and`12 are spaced apartJ
horizontally inv such' a ‘manner thatîedges «lll-‘and’
84 are at thedistanceZd-l-w, parallel; to one an?,
other, while the distance of tip Virom base 8_5
is Zd‘and thatV of tip‘W’ from ba'se_4_ i'S'fZdlFùr. " ' Í'
OffV Openings according to the invention.
The variable arë/a half-tracks 35 and 36, and
Openings 2| and 12 'are vrelated tof'à, system ofi
rectangular co-ordinates with axesÍ'X-TX
Y-Y. Axis XMf-X is parallel' to bases"_4'| 'ay _d'ï_-85ï‘
53 and 54, thus are characterized by the fact that
their modulated portion h'as a Width Whose ezro
and intersects edges 4l) and 84 at theirrnijdpoi '
value,_th_at is, the value for the rest position of
mirror |2, is one quarter its maximum value, that
is, _'the__value vfor the _maximum vibration of mir
ror I2.' This relationship between the zero and
i
and axis Y-Y .is parallel to edges Mirar-“111184, 1
spectively. The equation of parabolic edge 42
¿5'>
then
is again
maximum values of the _width of transparent por-_
f
luy-hieße@ ffi
(1)
tions 63 and` _64 becomes important whenjthe
electrical impulses applied to oscillograph 33 are
sound currents so that sound is to be reproduced
from track 52 on ñlm 5|. Its establishment then
effects a reduction of ground noise _which amounts
to 3 decibels. This result is sufficient to make
' While the equation of parabolic edge 86 is '
47ch2 being equal to w as has been pointedxoutfi`
the _application or the electrical methods ofg
ground noise reduction superfluous in a. great
number of practical-cases so that the production
of variable area soundtracks with' ground noise
reduction is materially facilitated by the present
invention.
'
hereinabove. The diiîerence’, therefore; ofi'ï‘the"
two segments determined on line lb'yledg‘es 40‘andf
42, and edges 84 and 86, respectively; aga-in’ equals
-4lchy“ (Equation 3),- and it again rb‘ec'omes‘ë zeröii
45 when
line l coincides With axis"X.-'-X; "'.The-lengthï'ï'
ofthe two'segments` is againkhz, or -
`
f:
_
_As shown in Figs. 2 and 3, and described here-4
inabove, openings 2| vand 22 are inversely posi
tionedvertically in that the tip of the one open-`
ing is in alignment 'with the base of the other
in this case, while.' _ ,
opening, and vice versa. As' further shown in
Figs. 2 and 3, openings 2| and 22 are inversely
is again the length. ofthétwosegnrénts de
positioned also horizontally in that their` straight
edges 4G and 44 face each other, While their 55’ mined on axis X-X by thesides of thetworightï
angled triangles Whose cathetes are. edgesl4ß`-a1î1<lîì,w
parabolic edges 42 and 46 are turned away from
4|, and edges84 and I85, respectiyel'y...«
...,
each other and open in opposite senses. In other
In Fig. 6, the opening 22 of Figsaanaéais
Words, openings 2| and 22 are arranged sym
associated with an opening 1|.. The correspond#
metrically withv respect to 4‘the point at which the
straight line lthrough their tips V and W is in co ing edges 44 and 80,' 45 land 8|., and .4B-,.andlf8_2_-.«
of openings 22 and 1| are of vequal length,"agie-Í~
tersected by the straight line through the endA
the tip W of opening 22 is in alignment.withthe>
points P and Q of their bases 4| and 45, respec- '
tively. This point coincides with the origin O
in_Fig. 3.
base 8| of opening 1| Whose tip V-’,~in its .turn-,fis
. in alignment with the base. 45 of. .opening 322:-,
However, the fact’that'openings 2| and 22'v 65 Openings 22 and 1I thus are alike but. inversely.,
have a center of symmetry, is immaterial as'far
as th'e present invention is concerned. That is
_to say, the invention may be carried out also
with pairs of openings Which are invertedonly'
vertically. Two such pairs of openings are shown
in Figs. 5 and 6 by Way of further example. Fig.
5 shows th'eopening 2| of Figs. 2 and v3 -asso-I
positioned vertically.
.
„
._ L.
More particularly, straight edges 44 'andi 4'5`ï`orj
opening 22 form a right angle, and so do .str-aigl__-1t.`
__ edges 80 and 8| of opening 1|. . Curvedlfedgef,46.Í
of opening 22 is opposite thezrightfangle formed,
by edges 44 and'45, andcurved. edge 82l‘offopèné.
ing 1| is opposite the right'.-¿ang_le.._ foigrnedll.„yiI
edges 80 and'ß I. The length of straight edges 44
ciated 'with an opening _12._ ‘v The corresponding
and 80 is 2h, that of straight edges 45 and 8| '
edges 40 and 84,_4|fand '85, and 42 and 86„of
openings 2| andÍ 12 are of equal length, and th'e>` 75 is w, and curved edges 46 and 82 are segments
2,404,137`
of twozparabolae rwhich are equal, but-diñîerently‘
positioned., Theparabola of' edge 46, which Operisi
to: they left', .has its vertex: at W and'` its axis- b
in this case, while
12
2
parallel to base 4:5.1so that edge 46 extends from
is again the length ofl the two segments _deter
mined on axis X-X by the sides, of', thetwo: right
angled triangles whose cathetes areedges 88 vand
tip/QW towardsy base» 45. The. parabola'of' edge 82‘
f opensé'also. .toy'the‘lef-a butv has its vertexgat V' '
andoitsfaxis a’ parallel to basev 8| so thatedge
82"-'extends from tip-V’ towards base 8|'. Finally, > >
openings 22A and 'Il arev spaced apartk horizontally
8|, and edges 84 and 85, respectively.
'
When the openings 2| and 'l2 of Fig. 5, th
openings. 22 and 1| of Fig. 6, or the openingsv'll
and. 72 of' Fig. 7, are in the screenZß oi the .optie
distance. of: tipfW. from base 8| is 2d and that of ‘Y Vcal system of Fig. l, screen 2i] is` adjusted sothat
bases 4| and 65, 45 and 8|, or8| and 85, extend
‘
‘tipY'f'from-'baseßisi2d+wu
Y
horizontally. Also, mirror i2 isfadjusted so that,
1
Openings .22. and 1li are related to a system of
¿.’ìfect'an‘gular- co-ordinates with axes X-X andv 15 atits rest position, line Z is halfway between bases
4| and 85, 45 and 8|, or 8| and 85.l The optical
ë-Yjr Axis. X--X is parallel to bases 45. and 8|
system of Fig; l then operates in the manner de
11d-intersects edges 44 and 80 at theirrmi'dpoints,
scribed hereinabove in connection with openings
Í' and axis Y-Y isparanei to edges mil and sur, its
in'suchia manner that edges 44 and 88 are at the , ,
1 distance-2d+w parallel to one another;y while the
2| and 22.v In each of the cases illustrated in
‘ _distancesifrom these edges being ‘d and d-l-w, re
‘ spectively..` The equation of parabolic. edge 46
Y
Figs. 5 to 7, therefore, the explanations aravalid
‘ which have previously been made as regards the
i theirisagain`
variation'inlength .of the lines of light’at slit Y2l
and recording point 38, andthe variation. inwidth
of theopaque >portions of half-tracks V35 `and 36,
of the transparent portions 63 and 64.v
2e. and
More particularly, when a print is made of the
idg-HL). 2:-, (ar-HZ)
while‘the; equation of parabolic edgeßi.’V is`
(2)
y
ï (er y
f
The difference,
push-pull class A variable area track produced
` therefore,A ofthe tWo- segments determined on
on film 3| with any one of thegpairs-ofV openings
` wherein. 4Ich2'- is equal to w.
linel by edges-82 and 86, and-edges 46 and 44,
shown in Figs.` 5 to.7, the track thusobtainedby
. respectively, again equals -47chy (Equation 3.)',
30 printing> has the general appearance of the track
`
and: it again becomes zero when line'l coincides
‘ with. axis X-X. The length> of the two seg'
.ments-is, againelehz, or
in this case, wime
INS
` 52 illustrated in Fig. 4. The, track >on such a print
hence is .again composed of the two variable .area
half-tracks 53 and` 54 which are complete, but
displaced 180° out of :phase in relation to one
354 another, and eachof the two >,transparent por
’ tions 63 and` 64 has again> a width. whose zero
value is one quarter its maximum value.'
_
112
The only difference between the trackspro
2
` ducedby means of the various pairs of openings
` is again the length of the two segments deter 40 is in the yrelative position of the straight bound~
mined- on axisnX-Xl by the sides of the two
aries of the opaque portions of half-tracks 35 and
‘ right-:angled triangles whose cathetes are edges 1 V33t..y and oîtransparent portions 63 and- 64. In
l 80y
ßlgjand edges 44 and 45, respectively.
the rvcase of openings 2| and 22, thestraight.V
l
j
1
1
.
i
‘
j
Openings 12’ and 1’|~ which` have been shown in
boundariesrof. transparent» portions 63 and. 64 c0
Figs.; 5 and; 6jas associated’with openings 2| and 45 ipcide Vwith thev inner boundaries 6l. allot-.68,Í re
22, respectively, may also be associated one with
spectively, ofhali-tracks 53 and 54, as illustrated
another as shown in Eig'. '7. "Openings 1| and: 12
in
4. With openings 2| and l2, thestraíght .
are alike, as will be seen from the description of
boundary of portion63 retains its position, while
Figs. 5 and 6, ¿and arranged so that the tip V’ of
that of .portion 64 coincides with the outer boundf '
opening 1| is in alignment with the base 85 of 50 _ary ‘i8 of half-track 54. With openings 22 and
opening 12 whose tip W', in its turn, is in align
7|', theV straight boundary of portion l6.4,has the
ment with the base 8| of opening 1I. The two
position illustrated in Fig. 4, while that of portion
openings are spaced apart horizontally in such a
63- coincides with the outer boundary 69. of half-v
manner that edges 80 and 84 are at the distance
track 53.v With openings 1| and 12., finally, the
Zai-|2211) parallel to one another, while the dis
straightboundaries of portions 63 and 54 coincidek
tance' of tips V’ and W' from bases 85 and 8|,
with outer boundaries 69 and 10, respectively.
respectively, .is- Zd-l-w. Openings 1| and 12 thus
The straighthoundaries of the opaque portions
are inversely positioned not only vertically, but
al'so‘horizontally‘.
of half-tracks 35 and 38 correspondingly change ,
,
their position since it, too, depends upon the dif
Openings-TI and 12 are related to a systemV of 60 ference in position, relative to each` other, of
` rectangular cna-ordinates with axes X--X and
vertical edges 48 and 44„ 4U and 84, 44 and 80,
Y-éY. Axis X-X is parallel to bases 8| and 85
andßß and 84, as illustrated in Figs. 2 and 5 to 7.
The openings shown in Figs. 2 and 5 to 7 all
and‘ axis Y-Y is. parallel to edges 80 and 8'4, its
have a shape which is derived from a rightV tri
distance from either edge being- d+w. > Parabolic 65 angle. When, therefore, theseA openings are in "
edges ‘82 and 86 then are again the lines con
the screen 20 of the optical system of Fig.. 1, the>
forming to Equations 4 and 5, respectively. The
half-tracks 35 and 36 on ñlm 3|„ and the half-,
difference, therefore, of the two segments deter
tracks 53 and 54 on nlm 5|, are unilateral varia-_ `
mined‘ron line> l by edges 82 and 80‘, and edges 84 i ble area tracks as illustrated in Figs. 1 and 4.
andi8'6-,1respectively, again‘equals -ßilchy (Equa 70 The invention, however, may also be employed
tionßl, and it again becomes zero when line ZY
when it is desired that the push-pull Class A '
coincides with axis X-X. The length of the. two
tracks on films 3| and 5|, respectively, be com
segmentsis again Ich?, or
posed of two variable area half-tracks ofthe
bilateral, or symmetrical, type. To achieve this "
75 end, there must be employed in screenvZíJ two
4
and intersects edges 80 and 84 at their midpoints, .
‘
.
.
ï'
.
‘
2,404,187
13;
r4'î
in Fig. 8 -by way of'exam-ple.
2
at bases9| and 95,1respectively, while.tlrneî'rli-s-v A
tance of parabolic edge 42 fromstraig’htiedge 40,
and that of parabolic edge' 46 from straight "edge
44, is w at bases 4| and 45, respectively. This
condition makes it necessary to reduce the factor
V1 towards edge9 I 'and arejsegments of two equal
parabolae whose vertices are at V1.1and whose
axes a1 and a2', respectively, are iparallel to Vedge
9|. The two parabolae, however, open in oppo
of proportionality k in Equations 1 and 2 by one
site senses, the parabola'of edge 92fopening to the
`
-.
the normal RV1, and that of yparabolic 'edges‘9'6 i
and 91 from the normal SW1, is
` y
Opening 90 has a straight edge 9| and is sym#
metrica] with respect to the line RV1 which is
perpendicular to edge 9| at its midpoint R. The
curved edges 92 and‘93 of opening 90 extend from
right and that of edge 93 `to the left.
'
But the distance of parabolic edg"e's’92_`andV 93 v'from
openings vwhose shape is derived from anfisosceles
triangle, such as the openings 90 and_94 shown
half in the equations for-parabolic edges 92,- 93;
‘
Similarly, opening 94 has a straight edge 95 and
is symmetrical with respect to the line SW1 which 15'
is perpendicular to edge 95 at its midpoint S.
96-,and.91.
y
‘
.
j
'
‘
‘
i»
The `equation of parabolic. edge 92 thus is
`
.a
T_he curved edges 96 and 91 of opening 94 extend
from W1 towards edge 95 and are Vsegments of
that ofy parabolic edge 93
two parabolae which are equal to one another, and
also to the parabolae of edges 92 and 9,3. The 20
parabolae of edges 96 and 91 have their vertices
at W1 and their axes b1 and b2, respectively, par
allel to edge 95. They open, however, in opposite
senses, the parabola of 4edgeySS opening tothe
left and that of edge _91 to the right. e
'
1
The distance of the tips V1 and W1 from th
bases 9| and 95 of openings 90 and 94, respec-`
andÍ that of parabolic edge 91 "
tively, is 2h. Since, furthermore, the four para
bolae whose vertices are at V1 andgW1 respectively,
are equal, bases 9| and 95,are of equal length 30
(w). Openings 90 and 94, which thus are alike,
Referring further to Fig. 9, theline „l is drawn
are arranged so that the tip V1 of opening 90 is in
parallel to bases 9| and 95. '_ 'Line'l traverses
alignment with the base 95 of opening 94 whose
openings 90 and 94 f5.0 that thereare determined
tip W1, in its turn, yis in alignment with the base
9| of opening 90. The two openings are `spa/ced`
onit again the two segmentspAB and CD, this
time,",however,by the curved edges 93 and92, land4
apart horizontally 1n such a manner that bases
96 yand 91, respectively; Segment AB, isr divided
9| and 95 are at the distance> 2h parallel'to one
by the normal _RV1‘into the two equal segments-
another, and that the distance of tips V1 andgWi
261+;
AK ‘and KB, and segmentCD is divided by the“
normal SW1 into thetwo equal segments CL and.
LD.
9 also shows that, for the same value of
y, segments AK,`KB,.CL, and LD, Aare equal to
the right members of Equations 7, 6, 8, and 9,v
Openings 90 and 94 hence areinversely positioned
respectively. According to Equation '7, therefore,
from bases 95 and 9|, respectively, .is
vertically.
.
'f
Y Y
In Fig. 9, which is drawn to a somewhat larger4
scale than Fig. 8, openings 90 ,and 94y are‘related
to a system of rectangular co-ordinates with axes
X-X and Y-Y. Axis X-X is parallel to bases
9| and 95 so as to intersect the two normalsRV1
escu
and SW1 at their midpoints G and H, respectively,
and axis Y-Y is parallel to thenormals RVi and
SW1 so that its distance from either normal is
’ nl
The co-ordinates of tips V1 and W1 then are
respectively, or (d+2lch2, h) and `
i ou’
respectively. This substitution of 27th2 forA ,
'w
y 655:
2
is based on the assumption that w in the case of
openings 90 and 94 equals win the case of open
ings 2| and 22, and in the latter case w is equal'
to 4kh2 as has been shown hereinabove. i
~
l
A comparison of Figs. _8 and 9 with Figs. 2 and
3, furthermore, reveals that the normalsRVi and
The difference of the two segments
and CD"
on line l hence v'is again alinear function of yl
since again
(3)
~
`
-
`
'
~ " -AB-'fcnàgikny
When, in the caseof Fig. 9, line l coincides..
with axis X-X,.seg1ments AB and CDbecÓme
segments A’B’ _and C’D’, respectively, asin the
SW1 and the straight edges 40 and 44 have the>
case of Fig. 3.
same length (2h) and are the tangents at the
vertex of the respective parabolae in each case.
posed of, the two equalsegments A’Gand GB',
But segmentA'B' now isco-m-v
' and segment C’D’ of the two equal segments C’H
2,404,137
'
'
and
ì
r6.5
15
X4-X, respectively,` represent different values of
the' horizontal extension, or width, of openings
y ,'Iherlengthrof 'each segment A’G.,îG1Bf`,
staand »Huus-
.
'f
f
2|, 22, 1|, 12, S0, and 94, respectively. Since,
is@
2:
' 5.
which value is obtained ¿by substituting O for y
in Equations 6 to 9 and solving them for their
right mem-bers. The length of segments A'B'~
and-07D'ì thus lis again kh2, or
'
'
J
`
that is, »half the length of theA two segments MEy
and 'FN which are 'determined on axis.
by
the sides lof the two iscsceles triangles with bases
9| and 95, and tips V1 and W1, respectively;
When openings 90 and 94 are in the screen 20
furthermore, the length‘of >those bases and seg
mentsfis equal to the right members of Equations
l, 2, and 4 to 9, for certain values of y, the width
of the openings increases infproportion to the
square of its distancel from their respectiveftipsv
V, W, V", W', V1,- and W1.v «Moreoven the widths'V
ofrlany. two paired openings-increase at'the same
rate :so that'they are equahalthough the `ope-r1
ings Aare inversely positioned vertically. Pairs ot
openings which' are thus positioned, and whose
widths vary in-l the manner set forth above, have
so ‘far :been shown and described only as em'
ployed in conjunction with the variable'area »re
cording optical system of Fig. 1.
of the optical system of Fig.'1, screen 20 is ad-` ` . Vtion V,contemplates their employment `also withv
certain variable density recording optical sys-L
justed so that bases 9| and, 9.5 extend. horizon-`V
tally, and the adjustment of mirror |2 is such 2o, tems of the mirror oscillograph type.
that, at its rest position, line Z is halfway be
l A variable 'density recording Voptical system in
tween bases 9| and 95. 'I‘he push-pull class A
which a pair Yof openings "according to the in
vention Y mayV advantageouslyv -be 'employed-is
`track produced on film 3| then is- composed of
shown in Figs. 11 to 13'by way of example. Since
two variable area half-tracks leach of which is
symmetrical about its vertical center line. Apart 25 this optical system is made _up mostly of the samel
parts as that of Fig, l, parts common to' the two
from their symmetry, however, these two half
optical systemsfare designatedïby the same ref
tracks have the same >characteristics as the uni
lateral half-tracks 35 and 36. That isrto say,
erence characters. It will thus be seen thatrthe
optical system of Figs. 11 to> 13 differs from that
the horizontal extension, or width, of the indi- ,
of Fig. 1 only in that the. microscope objective
vidual opaque portions of the twosymme'trical
|4 ¿and the spherical lens l5 of the4 latter `optical»
half-tracks varies. in proportion to the square
system have >been replaced in the former optical
ofthe amplitude of the `electrical impulses ap-`
.system by a cylindrical lens H4 whose cylinder.
plied to _oscillograpl'l` 33, but the difference inv
widthV of the >two opaque. portions isr a, linear
axis.` is horizontal, andv a pair of beam-splitting
function, of thatamplitu'de Also, the zero value 3,5; spherical lenses ||5 Yand ~||6, respectively. A
of this widthis onequarter lits maximum value
since the length of segments A’B’ and C’D' is
one quarter the length w of. bases 9| and S5. ' .,
When the push-pull class Asymmetrical var
front'elevation >of lenses ||5 and~||6 is-.shownirr
Fig. 14;-
_ .
f Cylindrical lens
Us forms, by its action. in the
vertical plane,.at recording point.,|30 an image.
iafble area track produced. on ñlm 3| by means of 40 of the two horizontal lines'of light ,appearing at
slit 21, while spherical" lenses ||5 and H6 form,
Openings 90 and 94 is transferred onto film 5|.
by printing, the resultant print has the general
yappearance of the track |02 shown in Fig. 10;
by their action in the horizontal plane, at the. `
same> position vtwo, distinct images of mirror l2..
There thus are produced at recording pointlßß.
Like track 52„track |02 is illustrated as being a
record of the full cycle of a sine wave. This 45 twohorizontal 'lines of light in _juxtaposition
The length of these two lines of light is constant,cycle is completely recorded on each of the two
' but half-tracks |03 and`|04 are’dìsplaced 180°.`
but >their intensity may continuously be varied
in accordance with the amplitude Vof theelectrical
out of phase in relation to one another trans
impulses applied. to Voscillo'graph 33. Since, in
half-tracks |03 and |04 which compose track |02,
verselyof ñlm 5|. Halfètracks |03 and |04 thus
all otherrespects, the optical system of Figs..11
are displaced in the same manner as half-tracks
to _13 operates in the same manner as the variable
53 and 54 of Fig.r4. Y
'
Half-track |03 is symmetrical about its verti
cal centerline |05-|05, and has a transparent
portion |06 which divides its opaque portion into
thetwo portions |01a and |071). Correspond
ingly, half-track |04 is symmetrical about its
vertical center line |08---|08, and has a trans
parent portion |09 which divides its opaque por
tion into the two portions||0a and ||0b. Fi 60
nally, the widths w1 and
f
2.,
density recording optical system shown in Figs, 1
to 3 of my U. S. Patent No. 2,312,259, granted
Feb, 23, 1943, reference is made to that specifica
tion by way of further explanation.
When, _therefore,„as shown by way of example
in Fig. 11, openings 2| and 22 are employed in
the screen 20 of the optical system of Figs. 11 to
13, the intensity of each of the two horizontal
lines of light at recording point |30 varies in
proportion to the squareof the amplitude of the
electrical impulses applied to oscillograph 33,
while the ,difference in ,intensity’of -the'tw'o’` lines
of light is a linear function thereof.
As ñlm 3|
of ytransparent portions` |06 and I 09, respectively, 65 moves vertically past recording point |39, there
vary each inproportion to the square of the
is thus produced thereon a photographic record
amplitude of the electrical impulses applied.` to
of the electrical impulses applied to oscillograph>
33, which record consists of the two variable
density tracks |35 and |36;- in juxtaposition.,Y
vor, Since the variation'in intensity Vof the two lines
of light at recording point |30 is continuous,
lIn lview of the foregoing explanations of Figs.
eachtrack r|35 and |36 lis, a complete record of'
2,> 3, ‘and 5 to 9, it will be understood by those.
the electrical impulses. On account of the in->
skilled in lthe art that the bases 4|, 45, 8|, 85,§
verted position of openings 2| and 22, however,
o‘scillograph 33, while the difference wi-wa is a
linear function of that amplitude; the zero value‘
of 'w1 Vand wz being one quarter their maximum
value.
`
\
.
9|., and 95, and the'segmentson line Z and 'axisI
track |36 is displaced 180° out of phase inrela
224.04: 1 37
‘
18
1.7
tion to'track |35 transversely of ñlm 3| so that ,
tracks |35 and |36 are the component -,half
tracks of a push-pull class A variable density
track
|31.
,
.
,
The methods of producing the variable density
track |31 and the variable area track 31 thus
both involve the following steps: Two horizontal
lines of light are produced in juxtaposition at
recording points 30 and I 30, respectively. >The
amount of light flux contained in each line of
light is continuously varied in proportion to the
square of the amplitude of the'electricalimpulses
applied to oscillograph 33, but the one amount
of light flux is varied 180° out of phase in relation
to the other amount of light flux. The variation
of the two amounts of light flux is accomplished
by varying either the length of the two lines of
light, or their intensity. Track 31> is obtained
reproduced from track |52. 'I‘his reduction is due
to the fact that, on account of the shape of open
ingsw2| and 22, each half-track |53 and |54 has a
light transmission whose zero value is one quarter
its maximum value ; the zero and maximum values
of the light transmission of half-tracks |53 and
|54 being its values for the restposition of mirror
I2 and its -maximum vibration, respectively.
The ground noise reduction obtained by the
employment of openings 2| and 22 in the optical
system of Figs. 11 to 13 amounts Yto 6 decibels.
This-result is sufûcient to make the application of
the electrical methods of ground noise reduction
superfluous in a great number of practical cases.
The4 production, therefore, of variable density
sound tracks with ground noise reduction isV ma
terially facilitated by the present invention.
'
In the place of openings 2| and'22 there may
be employed in the screen 20 `of the optical sys
in the first case, and track |31 in the second_case.
It is well known in the art that any kind of 20 tem of Figs. `11 to 13 also the openings 2| and 12
sensitive emulsion with which ñlm 3| may be
of Fig. 5, the openings 22 and 1| of Fig. 6, the
coated,’respon'ds linearly not to its exposure, but
openings 1| and 12 of Fig. '1, or the openings 90
to the logarithm thereof. The variation in den
and 94 of Fig. 8. Substitution of any of the pairs
sity, therefore, of half-tracks _|35 and |36 is not
'proportional to the square’ of the amplitude of
the electrical impulses applied to oscillograph
33, although the variation in intensity of the two
lines of light at recording point |30 is so propor
tional. But, for making a print of track A|31
of openings *shownV in Figs. 5 to 8 for openings 2|
and 22, however, does not aiîect either the ap
there may be employed methods, generally known .
to those skilled in the art,'by which the complete
constant length whose intensity varies in propor
tion to the square of the amplitude 0f the electri
photographic process is controlled so that the
cal impulses applied t0 oscillograph 33.
‘light transmission of the print is proportional
to the exposure of ñlm 3|.
`
_ VA print obtained in this manner is illustrated, y.
by way of example, in Fig. 15. This figure shows,
vprinted on ñlm 5|, a push-pull class A variable
density track |52 which is composed of the two
half-tracks |53 and |54 in juxtaposition. Like
tracks 52 and |02, track |52 is assumed to ‘be a
record of the full cycle of a sine Wave. This
cycle is completely recorded on each half-track
v-| 53 and |54, but the two half-tracks are displaced
180° out of phase in relation to one another.V That
is to say, the region |55 of largest light transmis
sion on half-track |53 is opposite the region |56
tof smallest light transmission on half-track |54
transversely of film 5|, and the region |51 of
"smallest light transmission on half-track |53 is, in
the same sense, opposite the region |58 of largest
light transmission on half-track |54.
_Since track |52 was obtained by theV photo
graphic methods referred to above, its light trans
mission is proportional to the exposure of ñlm 3|
which, in its turn, is proportional to the inten- >
sity of the two lines of light at recording point
|30. The light transmission of each half-track
|53 and |54 hence varies in proportion to the
square of the amplitude of the electrical impulses
pearance, or the properties described hereinabove,
of half-tracks |35 and |36, and |53 and |54, re
spectively. In all cases, there are produced at're
cording point |30 two horizontal lines of light of
y
In considering Fig. 15, Iinally, it should be borne
`in mind that the Variation in light transmission
of> a variable density track can be illustrated only
by diiîerences in its shading, and that it is well
nigh impossible properly to indicate, in a shading
made by hand, the particular variation in light
Vtransmission which half-tracks |53 and |54 have
_in accordance with the present invention. Actu
ally, the variation in light transmission of hali
tracks |53 and |54 is the exact counterpart of the
variation in width of transparent portions 63 Aand
64 as diagrammatically illustrated in Fig. 4. Fig.
15 hence is merely a crude illustration of the
push-pull classV A variable density track |52. '
In an actual embodiment of the optical systems
of Figs. 1 and 1l to 13, thedimensions of the
_images on screen 24 may be different from those
of the openings in screen 20. Such enlargement
or reduction, which depends upon the ratio of
imagery chosen for lens 23, `does not affect the
validity of the explanations made hereinabove,
since it doesnot involve a change in proportion.
Tracks 52, |02, and |52, lare shown in Figs. 4,
10, and 15, and have been described hereinabove,
as printed from iilm 3| onto iîlm 5|. But these
tracks may be produced also immediately on ñlrn
37| by adapting the optical systems of Figs. 1 and
applied to oscillograph 33, while the difference in
l1 to 13 for recording in accordance with the >re
,light transmission of half-tracks |53 and |54 is a `
versal method.
linear function of that amplitude. Since, further
more, the light transmissions of half-tracks |53
Y
y
ï
When the amplitude oi the electrical impulses
applied to the oscillograph 33 of the optical sys
tems of Figs. l and 1l to l3'is very large, the
yand |54 vary 180° out of phase in relation to one
another, the light transmission of half-track |53 .165 images on screen 24 may be deflected to such a
increases when that of half-track |54 decreases
:degree that their tips and-bases cross slit 21. This
and vice versa.
I
'
Like tracks 52 and |02, track |52 may be repro
duced with any conventional push-pull repro
ducing system, and the reproduction of the elec
effect of over-modulation interrupts the exposure
of filrn~3|. VIt may be avoided by combining the
openings shown in Figs. 2 and 5 to 8 with an ad
ditional opening, or openings, of suitable shape
I trical impulses recorded thereon is undistorted
in suchl a manner that the .two ormore openings
for the reasons set forth hereinabove in connec
y‘form a single opening whose shape is again sub
stantially triangular. This expedient, which. in
.itself is r»well known inthe art, is illustrated,> byr
tion with the description of track 52. Also, when
those electrical impulses are sound currents, a re
_duction of ground‘noise is effected when sound `is :75 .way of example, in Figs, 16 and 17 ` as> applied@
25,404,137
,
,
20
519
spectively.A
I f
`
,
total «width‘and the ¿width-»of openings |6ï| rand
|63, respectively, so that it isequal to the-total
openings 2| and" 22, and openings 90 and 94, re
ï
width of the 'former openings. The» ¿eiïective
width of all openings thus is proportional tothe
Fig. 16 »shows how, inY order to obtain the» de
'sired'r'esult, opening2| may be combined with the
two-rectangular openings |6| and |62, and open
ing 22 with the two rectangular openings |63 and
|64, so'v as to form the substantially triangular
openings |2| and |22,` respectively. IOpenings
square of its distance'from Vtheir tips. But Vthe
total width of all openings increases in propor
tion tothe squarey of its distance from theirtips,
no matter whether it is equal to, or larger than,
Av|^6| and |63 are equal, and so are openings |62 and
their effective width. It is understood, of course,
|64. >Openings 2|, IGI, and |62, are varranged so 10 that in the cases illustrated in Figs. 16 and l'î, the
tips ofthe openings are rectangular rather than
‘that one of the vertical edges of'opening |6| coin
punctual as they are in the cases illustrated in
cides with the vertical edge 40 of opening 2|.
Figs. 2 and 5 to'8,
l
Y
'
Since, however, this edge'of opening |6-| is longer
`than edge 40, its portion |65 extends beyond the
It -will thus be seen, when openings-such as
tip V of opening 2|. yOnevof the horizontal edges 15 openings |2| and |22, and |90 and |94, are _in
the'screen 26 vof the optical systems of Figs; 1
of opening |62, on‘the other hand, coincides with
the base H4| of opening2| and the horizontal edge
and 11 to 13, the amount of light ñux contained
in each of the two horizontal lines of ylight at
|66 of opening |6I.
recording points r30 and |30, respectively,'is con
Correspondingly, openings 22, |63, and~|64, are
>arranged so that vone of the vertical edges of open 20 tinuously variedl again in proportion to the square
of the amplitude ofthe electrical impulses ap
ing |63 coincides with the vertical edge 44 of open’
plied to oscillograph 33. In 'case suchopenings
'ing 22. Since, however, this edge of opening |63
are employed'with the optical system of Fig. "l,
is longer than edge'44, 'its portion |61 extends
beyond the tip W of opening 22. One of the hori
thereiorethe push-pull class A tracks recorded
zontal edges of opening |’64,'onfthe'other hand, 25 on kfilm 3|, and the prints m'ade of these tracks
coin'cides‘with the base 45 of opening 22 and the
on film 5|, are composed of two variable area
horizontal edge |63 of opening |63.
half-tracks, and each half-track ‘has a`modu
v TheA transìtion'from the parabolic edges 42 and
lated `portion whose width varies again in pro
46 of openings |2-| and |22, respectively, to their
portion to the square of that amplitude. ' How
straight edgesA |65 and |61, respectively, is a 30 ever, lsince a part of the width of the openings
smooth one because Vedges |35 and |61 are the
here under discussion is constant, a part of the
tangents at the vertices of parabolic edges 42 and
width of this modulated portion is constant, too.
46, respectively. '
Y
' 1
The modulated portion hence has now an eiîec
In Fig. 17, opening 90 is combined with open
l tive width which is equal to its total width less
ings |6| and |62, and-opening 94 with openings
the constant partv thereof. This effective width
|63 and |54, so as to form the substantially tri
is proportional to ’thev square of the amplitude
angular openings |90 and |94, respectively.
referred to above and its zero. value is one-quarter
its maximum value, Vas in the case of the modu
Openings 90, |6l, and |62, are arranged so that
opening | 6| bisects opening 95. Opening 90 is
lated portion yof half-tracks 35 and 36,53 and l54,
thereby divided into the equal portions 93a and 40 and |03 and |04, whose effective width is equal
'90b with bases 9|a and 9|b and tips V2 and V3,
to its total width.
'
'
respectively, and the portions |1| and |12 of the
In case openings such as openings |2| and |22,
vertical edges oi opening |6| `extend beyond tips
and |90 and |94, are employed with the optical
V2 andA V3, respectively. Opening |62, on the
system oi Figs. 11 to 13 and prints are made on
other hand, has a horizontal edge which coincides 45 film y5| of the push-pull class Atracks recorded
, with bases 91a and SIb, and the horizontal edge
on iilmf‘3l, and in accordance with the photo
graphic methods Y mentioned hereinabove, the
prints are composed of two variable density »half
Correspondingly, vopenings 94, |63, and |614, are
arranged so that opening |63 bisects opening 94.
tracks, and each half-track has alight transmis
Opening 94 is thereby divided into the equal por 50 sion which varies again in -proportion to -the
tions 94a and 94h with bases 95a and 951) and tips
square of the amplitude of the electrical impulses
W2 and W3, respectively, and the portions |13
applied to o_scillograph 33. However, since apart
andV |14 of the vertical edges of opening |63 ex
of the width of the above'openings V'is constant,
tend beyond tips W2 and Wa, respectively. Open
a part of this light transmission is constant, too.
ing |64, onthe other hand, has a horizontaledge 55 The variable density half-tracks hence have now
which coincides with bases 95a and 95h, and the
an eiîective light transmission which is equal to
horizontal edge |68 of opening |63.
I
their totaljlight transmission less its constant
The transition from the parabolic edges 9_2 and
part. This effective light transmission is propor
93, and 96 and 91, of openings |90 and |94, re
tional to the square of the'amplitude réferredto
spectively, to their straight edges | 1| and |12, and 60 above, and its zero value is one-quarter its maxi
|13 and |14, respectively, is a smooth one because
mum value, as in the case ofY half-tracks |53 and
edges |1V|, |12, |13, and |14, are the tangents at
the vertices of parabolic edges 92, 93, 95, and 91,
respectively.
|54 whose effective light -transmission is equal
to their total light transmission.
i
lWith openings such asopenings 2| and 22, an
, 90 and 911|,Y their total width is utilized for varying
thev two amounts of light flux passing through
the slit 21 'of the optical systems of Figs. 1 and 11
to 13.A With openings such as openings |2| and
65
'
`
Having thus described several embodiments of
my invention, `I wish to point out thatfit is not
limited to the speciñc structures shown, >but is
of the scope of the appended claims; '
What I claim is:
`
f
_
1'. The method of producing on a film a photo
|22, andv |90 and |94, however, that part'of their 70 graphic record of electrical impulses whichin
width which is 'equal to the horizontal extension,
cludes moving said 'ñlm past a recording point
or width," of openings |6| and |63, respectively,
in a substantially vertical direction; producing
vdoes not eiîect a Vvariation of the light flux since
'it is constant. The effective Ywidth 'of the latter
4light in'juxtaposition,"'each ’of `'s'a'i'd 't'wo"linesfof
openings> hence is the diiîperence between their
light'conta'ìning 'a Vvariable amount of iight‘ñ’uxf:
at said 'recording >point 'two h'o'rizontal " lines of
2,404,187
21
22
and continuously varying said amount in proporn
tion to the square of the amplitude of said elec
trical impulses, but varying the amount of light
of said half-tracks being a complete record of
said electrical impulses and having an effective
light transmission which is proportional to the
square of the amplitude of said electrical im
pulses, the zero value of said light transmission
being one quarter its maximum value.
10. A photographie .push-pull. class A track on
flux contained in the one of said two lines of
light 180° out of phase in relation to the amount
of light flux contained in the other line of light.
2. The method of producing on a film a photo
graphic -record of electrical impulses which in
cludes moving said film past a recording point in
a film, said track being a record of electrical im
pulses, and composed of two half-tracks displaced
a substantially vertical direction; producing atY`
said recording point two horizontal lines of light
in juxtaposition, each of said two lines of light
being of variable length; and continuously vary
ing said length in proportion to the square of the
180° out of phase in relation to one another trans
versely of said film; and each of said half-tracks
being a complete record of said electrical im
pulses, and having a light transmission which
varies in proportion to the square of the ampli
v amplitude of said electrical impulses, but varying 15 tude of said electrical impulses.
ll. In an optical system, a screen having two
the length of the one of said two lines of light
openings which are substantially triangular and
180° out of phase in relation to the length of the
alike; each of saíd‘two openings having a tip,
other line of light.
and a horizontal extension which increases in pro
3. A photographic push-pull class A track on
portion to the square of its distance from said tip;
a film; said track being a record of electrical
and said two openings being spaced apart hori
impulses, and composed of two variable area half
zontally and inversely positioned vertically.
tracks displaced 180° out of phase in relation to
12. In an optical system, a screen having two
one another transversely of said film; and each
openings which are substantially triangular and
of said half-tracks being a complete record lof said
alike; each of said two openings having a tip,
electrical impulses, and having a modulated por
and an effective horizontal extension which istion whose width varies in proportion to the
proportional tothe square of its distance from
square of the amplitude of said electrical im
pulses.
4. A push-pull class A track according to claim
3 and in which said modulated portion is opaque. ‘
5. A push-pull class A track according to claim
3 and in which said modulated portion is trans
parent.
said tip; and said two openings being spaced
apart horizontally and inversely positioned verti
cally.
.
13. In an optical system, a screen having a first
opening and a second opening, said first and
second openings being substantially triangular
and alike; said first opening having a first tip,
and a first horizontal extension whichinoreases
film; said track being a record of electrical im
in proportion to. the square of its distance from
pulses, and composed of two variable area half
said
first tip; said second opening having a second
tracks displaced 180° out of phase in relation to
i tip, and a second horizontal extension which in
one another transversely of said film; and'each
of said half-tracks being a complete record of 40 creases in proportion to the square of its distance
from said second tip; said first and second hori
said electrical impulses and having a modulated
zontal extensions increasing at thegsame rate;
portion whose effective width is proportional to
and said first and second openings being spaced
the square of the amplitude of said electrical im
apart horizontally and inversely positioned verti
pulses, the zero value of said width being one
cally.
quarter its maximum value.
14. In an optical system, a screen having a
7. 'I'he method of producing on a film a, photo
first opening and a second opening, said first and
graphic record of electrical impulses which in
second openings being substantially triangular
cludes moving said film past a recording point in
and alike; said first opening having a first tip,
a substantially vertical direction; producing at
and a first effective horizontal extension which is
said recording- point two horizontal lines of light 50 proportional to the square of its distance from
in juxtaposition, each of said two lines of light
said first tip; said second opening having a second
being of variable intensity; and continuously
tip, and a second effective horizontal extension
varying said intensity in proportion tothe square
which is proportional to the square of its dis
of the amplitude of said electrical impulses, but
tance from said second tip; said first and second
varying the intensity of the one of said two lines 55 horizontal extensions being equal; and said first
of light 180° out of phase in relation to the
and second openings being spaced apart horizon
intensity of the other line of light.
tally and inversely positioned vertically.
8. A photographic push-pull class A track on,
15. In an optical system, a screen having -a
a film; said track being a record of electrical im
first opening and a second opening; said-first
pulses, and composed ofy two variable density half
opening having a first tip, a first base, and a
tracks displaced 180° out of phase in relation to
first width which increases in proportion to the
one another transversely of said film; and each
square of its distance from said first tip; said
of said half -tracks being a complete record of said
second opening having a second tip, a second
electrical impulses, and having a light transmis'
base, and a second width which increases in pro
sion which varies in proportion to the square of
portion to the square of its distance from said
the amplitude of said electrical impulses.
second tip; said first and second widths increas
9. A photographic push-pull class A track on a
ing at the same rate; said first and second bases
film; said track being a record of electrical im
being equal; said first tip being in alignment with
pulses, and composed of two variable density half
said second base; and said second tip being >in
tracks displaced 180° out of phase in relation to 70 alignment with said first base.
one another transversely of said film; and each
JOI-IN A. MAURER, JR.
6. A photographic push-pull class A track on a
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