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Патент USA US2133820

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Oct. 18, 1938.-
Filed Sept. 30, 1937
2 Sheets-Sheet l
Oct. 18, 1938.
Filed Sept( 30, 1937
, 2 Sheets-Sheet 2`
TPattentecel Oct. 18,1938 l
I- 2,133,820
- to Radio
K'ellorts Moorestown,
oi' Arne'rlca,N.a corporation
J., assignor
'' lot Delaware.
Application 'September 30, 1931, Serial No. 166,69'2~
. 5 Claiins.
(0.1~ 271-2.3)
This invention `relates _to film-feeding mecha- “
nism and especially for feeding negative film and ' 01' incidence of theillm Will be varied a. úaatimum
aniountfor a mini um .variation in size_ of the
. positive tiim stock in intimate contact through a " iilmloop.
contact printer without slippagebetweian the illms
5 and with compensation_ -for diiì'erences in the
? Other andincidental- objects of my invention
Al iilinffeeding device of "the general type
reading of_ the following speCitication and trom
an inspeetion of_- the accompanying drawings, in
lengths of the tllms,due to shrinkage or expan- ' will be apparent to those SkillB'd'lli the art from_ a 5
here involved qwas disclosed and claimed in Bed
ford Patent 1?754,187,-and a printer based on this
10 principle was described in the Journal of the 80
Figure 1 is an elevation
"~ of' a commercial form
of nonslip printer built in accordance with the 10
ciety oi -Motion Picture Engineers for August
.aforiasaid Bedford Patent 1,754,187,
- 1934, in _an article by 0. N. Batsel, and thépíesent
previous devices.
Figure 2 shows thê-simplest'embodiment of my
invention pertains to a impiovement?upon the
invention_ wherein _a single roller is used to in
crease_the angle oi incidence of' the iilm With a
In the apparatus previously described as Just
given variation in looplength,_
referred to, the-131m travels either in `“a free loop
or in a loop passing- around a movable idier to .~ ` Figure 3 is a_ diagram of the forced relations in'
the arrangement of Figure a for two positions of
the printing point, and. the lengthof tliis'loop (of
_ the roller 8,
"positive film stock) varies in accordance with the
20" difference _in length of the positive and negative
'Figure 4: is-an elevation of a nflodiiied form of
The loop length is -not directly controlled printerwlierein the 111m tension rema-inssub- 20 '
.in any manner and the loop occasionally has a" stantially constant iri?espective of the `variations
in loop length and angle-of incidence,
tendency; to become unwieldy -or-itodbecome too
~ _
- Figure 5'shows a inodiiication of the roller ar
rangernent of Figure 4:,
tight, either oi! whichattects, to a certain extent;
.25 the. position of the sound tr`ackprint upon'the
film. Itis apparent to those Skilled inthe art " Figure 6 shows a ifurther Inodification or Figure gõ
that printers`of the type here referred to_ are used 5 tvherein the linkage between the rollers is slight
modified so that the roller . 2.0 . moves some
almost exclusively in the printing of sound track ly
What less than the roller 8,
from the negative to the positive iilm or in malr- ›
Figure f'? 'shows _a form of the Invention wherein
the shortening of the loop is'efiected by displac- 30 '
It will be apparent from an inspection of _the .ing the sprocket II slightlyto the left. '
30 ing duplicate negatives and that they are prac
tically never used in making picture prints.
patent or article above referred to that the prin-g ~
in 8Fig.:'i
the relative
of .the apparatus
length of_
ciple of the _Bedford printer depends upon the
one oi' the arms is increased_ t?modifythe result- .
35 changing of the' angle of incidence ofthe posi- - produced,
. `35
tive iilm stock upon 'the supporting di'tim at the
printing point, to “produce a variation in the › 'Figure 9 shows in “greater detail a further m_odi-_
. effective length of this ?lin stock at the, printing iication of the apparatus “of Figure8 intolving a
slight change in the linkage which' has
point in a manner which` hereinaiter de “further
lproven. quite satisfitctory,
o10 scribed in greater detail, and to thereby secure
Figure 10. shows a' type' oi' toggle spring-and anh' ?rol
compensation for the ~ vatiation in iilm length Íeouiva
t -countetweight which_ may be used in
_ which may. be due, for example, to shrinkage. _ In
the present invention I have provided an appa-. establi ng a- biasing force inthe several types
ratuswhich .varies this angle of incidence in a›
45 verysensitive manner and in which the Variation
in loop length required to produce a given change
v in'the angle of incidence is a minimum, thereby ~
of linkages shown in the other figures,
`liigureí 11 Shows the loss of control ofangle at
low iilm tensions in the tli'pe oi' scpparatus shown 4.5
inFig. 2, and
Figure 12 Shows a modiiication of the appara
-retaining the relative position of the sound track ,tus of Flg.-2 wherein an' auxiliary roller is' pro- .
on the negative and print. as nearly similar as
~vided to compensate for_ the elasticity of the film. '
One object oi' myinvention is to provide_ an
improved modiiication of the printer`hi' the said
Referring nowto the drawings,
50 -
~- j Figure 1 shows an arrangement oi' rollers which
- '
has been employed' in several successful models.
Another object oi' my invention is to› providea The iilm passes around a drum l which _is pro
525) nonslip printer in which a maximum amount of .Viderl witlia' damped ?ywheel in order that it
compensation for variations in film length_ will may run at .uniform speed. Rotation is imparted 55
thedrum by means of the negative iilm 2_which
be secured with a minimum variation in iilm loop to
ls prôpelled by sprocket 3. 'I'he unexposed posi
Another object oi' my invention is-to provide a ' tive iilm or "raw stock". 4 is maintained in conu_ ~
Bedford patent.
60 printer oi the type described vrlietem the angle
tact with the negative iilm at the printing- point _
5 by means_ of &. pressure roller G' which is held co
- ~
- 8,138,820
punched or penciled mari: corresponding to a
given starting mark on the picture negative. He
incontact by a spring or springs, not shown.
An optical system 'I projects light' upon the films
at the point 5 where they are in contact. The
must then thread the same "raw stock" into the
printer with a certain_ relation between the
"raw stock" may be guided by means of a Shoe _sound
position of the same mark on the “raw stock"
or slide as illustrated in the above-mentioned. and a certain starting mark on the soundnega
Bedford patent, but is preferably passed around
tive. Since the sprockets 3 and II control the
of both films, the operator must perform
and mounted on a swinging arm 9 which is piv
his threading operations with reference to these
oted at Ill so that it may move back and forth sprockets. The actual point on the "raw stock" 10
10 in accordance with the length of the loop of which receives the exposure from a given point
“film I3 between the feeding sprocket IIr and the' ' on the negative depends upon the relative posi
printing point 5.
tions at the printing point 5 which in turn varies
The sprockets 3 and' li (which are shown .as with the length of the film loop I3. There will
having the Same number-of teeth) run at the thus be departures from exact synchronisni, the
15 same speed. This is a requirement for printing amounts of such departures being proportional
a synchronous film. In view, however,_ of the to the difference in the length of "raw stock" loop'
Variations in shrinkage of the films, their linear
a guide roller 8 which is provided with hanges
'as the operator threads up the printer and as it
actually runs. It is obviously desirable to re
speed may not be exactly the same even though
the number of sprocket holes passed per unit of
duce these Variations 'in synchronism to the
smallest practicable amount. This is especially
is taken care of without slippage by changes in_" important if a printer of this type is' to be used
the angle at which the "raw stoc " approaches for 16 mm. film, since in this case a given change
the printing point 5. If the negative is consider
in loop length corresponds to a greater time dif
4 ably? shrunke , the linear speed of the negative
ference and synchronism error than would be
the case with 35 mm. prints.
i '
20 time is the same. 'I'his difference in linear speed
at point 5 where the two illrns are held in con
tact is low. Under these conditions, sprocket II
tends to feed the "raw stock" through more rap
idly than it is carried past the printing point;
30 therefore, excess film .accumulates in the loop
l3 between sprocket II and printingppoint 5. A
light spring pressure (not shown) causes the
guide roller 8 to move over to the right, under
these conditions, to take up thc excess film. The `
result “is that the "raw stock", now presents 8.
concave surface to the negative. As "Lis well
known, the material on the concave surface of a
bent strip is under compression, and therefore
this part of the "raw stock" is shortened. An
40 equilibrium position is thus reached at which the
shortening of the c"raw stock" surface due to
compression is. just sufficient to cause it to move.
at the correct speed without slipping. If, on the
other hand, the negative has little shrinkage. the
drum runs faster and the loop of "raw stoc "
film tends'to become shorter, the guide roller 8
then moves to the left as illustrated at position B.
Under these conditions, the "raw stock" presents
a convex surface at the point of contact with the
negative and thus the surface becomes stretched
50 until equilibrium is again reached. The mean
linear speed of the "raw stock" is the average
of that of its stretched and compressed surfaces.
Pressure roller 8 may run at any speed and the
speed of the "raw stoc " surface on this side is'
not a. factor in the rate of film travel. Thus, when
the guide roller is in position li, the net or center
line speed of the “raw stock" is greater than that
of the concave or propelled surface, while if the
00 guide roller is in position B, the net speed is
lessthan that of the propelled surface.
The foregoing discussion of the action of the
printer is a rlestatement of, what is described in
the aforementioned paper by C. N. Batsel.- It is
85 evident that the operator cannot count on pre
dicting the size of the loop IS of "raw stock" be
tween the feeding sprocket II and the printing
point 5. Since in ordinary practice, a picture
It is therefore a purpose of my invention to
provide an arrangement by which the necessary
changes in the angle at which the "raw stock"
approaches the printing point of a nonslip print
er are produced by a minimum change in loop
Figure 2 shows a roller arrangement which has
been employed in some model printers, and which
slightly reduces the variations in loop length.~
The feeding sprocket II in Figure 2 has been
raised with reference to its position in Fig. 1 so
that the filin bends only slightly in passing
around guide roller 8. ,An objection to this ar
rangement is that as the guide roller moves to 40
ward the position' B at the left, an excessive
degree of min tensionis required “to hold the
roller in this position. If the roller is to be main
tained in contact with the film it must be urged
to the right by means of a spring or counter 45
weight (not shown). Figure 3 shows the force
relations for positions, A and 1.3 of roller I.
Arrow II represents the tension on the film be
tween roller 8 and printing point 5 for posi- '
tion A. Arrow IE is the vector of. the tension
between sprocket I'I andnguide roller 8. v The re-, ~
sultant _IG is seen to be comparable in magnitude
with the tension vectors M and I5. The con
_ditions for position B areshown by Vectors I'I, IB
and |9~ If a spring is applied to the arm 9,
the tangential force represented by vector IS
must be_ sornewhat greater than is required of
the vector IS owing to the increased tension on
the spring, and owing to the _obtuse angle be
tween vector I'I and IO, they must be excessively
large in order to produce an adequate force IS.
If too much film tension- is required, slipping is '
likely to occur at the printing, point 5, and the
It la_
desirable that the position of the guide roller 8 be
controlled by small and nearly constant film ten
Sion. In this respect, the arrangement shown in
Figure 1 is superior to that shown in Figure 2.
Fig. 1, the film between the sprocket II and
is to be printed on the same him, it is evident that
roller 8 pulls in a direction nearly perpen 70
both picture and sound must be printed before
70 the film is developed and therefore no photo- ' dicular to the arm 9. Even here, however, the
tension is not constant, because of the
graphically printed marks on the "raw stock" film
change in the direction of pull of the film below '
can be utilized for registering the film for,ac
curate synchronism. The operator must thread the guide roller.
'lli his uraw stock" into the picture printer with. II
benefits of the nonslip printerl are lost.
The conditions to be met in providing li roller 76
arrangement requiring substantially constant .film
tension may be understood byreterence to Fig. 4.
lyli'lg'. 5 shows an arrangement providing more
nearly the relative positions employed in present
In Fig."4l an extra movable roller is shown, sup'- v
printers but .still employing the same principles.
ported on an arm 22 which is pivoted at a. point
illustrated in Pig. 4. The arrangement shown
The arms 9 and 22 are connected by a link ~ das
in F'ig. 5 is similar to that in Fig. 4: in that the
stretch of tree lilli! between the guide roller 8
tance apart. Pivot points l0 and 23 are located and
the printing point 5 is substantially parallel
in line with the printing point 5 and a corre
'. 23.
21 maintaining rollers 8 and 20 a constant dis
and equal in length to the supporting arm 9.
Likewise, the stretch of film between the sprocket
The rollers are supported by this linkage in such ' II and extra roller 20 is substantially parallel to '10
sponding point 24 where the illm is held between
10 the sprocket II and the sprocket pad roller 25.
arm 22. The him between rollers 20 and 8 is
not parallel to link 2l_ but is nevertheless of con
a manner that each stretch of uhsupported film
is substantially parallel to one of the links in
stant length. As “previously pointed out in the
discussion oi Fig. *1,-the linkage as shown in
the supporting system. Thus tension between
roller 8 and printing point 5 is resisted entirely
by a compressional stress in arm 0. tTension be
tween rollers 20 and 8 is resisted entirely by còm
pression in link 2! and tension between' point 24
and roller 29 lis resisted by compression ~in arm
20 22. There is thus complete equilibrium, and ten-.
Sion on the iilm has no tendency to cause a dis
Fig. 5, wherein the stretches of free film are par
allel to the supporting arms, provides no change
in- loop length as the rollers are shiited, and
therefore tension on the iilm cannot cause the
rollers to move. The proportions of the linkage
must then bê slightly modiiied so that movement 20
of the rollers to the left is accomplished by. a
placement of the linkage in any direction.
Neither does the total loop length between points " small but continuous shortening of the loop.
Fig. 6 shows a modification whereinthe posi
24 and 25 change at ali by shiiting the position tion
of the connecting link 2I is' shiitedy so that
25 of the rollers. This of course is an impossible
moves somewhat less than roller 8, and
condition for operation, since a shortening of the Fig. '7? 20
an arrangement wherein theshort
loop would only _result in increased tension and ening of the-loop
is etfected by displatting the
would fail to move the rollers as desired. “II, sprocket Il slightly to the left. It “is not essenhowever, a slight change is inade from Fig. 4, tlal that the pivot points I0 and 23 be placed on
30 the required conditions can be readily obtained.
the points 5 and 24 at which
For example, if the point at the link 2l the sameislevels-as
restrained from moveinent;
is pivoted to arm Sis lowered _(making the_ link the“iilm
In general, as one of the arms (for example,
2I no longer exactly parallel to the film between
9) is lengthened, the Stretch oi' tree film at
rollers 20 and 8) so that roller 20 executes slightly `
35 less motion than roller 8, then as the rollers move _' the. other end of the linkage should be corre
spondingly lengthened. 'I'his results in an ai'to the left they will approach each other or the
rangement such as shown in Fig. 8~ There are,
tangent between them will become Slightly
shorter. Under these conditions, a shortening of
e iilm loop will cause the rollers "to move to
110 the left as desired. Another expedient consists
in retaining the linkage as shown inIE'ig. 4 but
moving the sprocket slightly to the left. This
causes the film tangent between point 24 and
roller 20 to shorten as the rollers move to the
The iilm must perform mechanical work
45 left.
in displacing the rollers to the left against spring
action and it canponly perform this mechanical.
work “if it is under some tension and the loop
becomes shorter. The force which the illm under
50 a given tension can exert on the roller to produce
displacement may be measured by the amount
oi loop Shortening per unit change in roller posi
tion. The smaller the changegin loop length, the
greater must be the iilm tension to overcome a~
given b?asing spring tension urging the rollers to
the right. The best design is therefore a corn
r promise between the desirability of small .change
_in loop length and small iilm tension. The most
desirable conditions are attained ii' the biasing
.60 spring or counterweight' is as light as will be con
however, various modiiications in the proportions
~ of the linkage and positions of the rollers which
will give satistactory results.
Pig, 9 shows the arrangement employed ina
model which has been built and operated. In this
model -proportions were changed and. rollers
shitted until an arrangement was found in which,
throughout the total required range of movement
of guide roller 8, there is a substantially constant
ratio of movement of guide roller 8 to change in
total loop length. In whatever design is used, it
is desirable that the guide roller 8 be placed as
close as practicable to the pressure roller I0 so
that a small movement of the guide roller causes 50
a' large change in angle of the film. The essen
tial characteristic of., the arrangements is thats.
second roller is employed; and the two rollers are
connected in such a. way that the tendermy of
the movement-of the shaft Orguide roller 8 to .
shorten the loop is accompanied bya movement
of the second roller 20 which ofi'sets the shorten
“ing ei?ect or, in other words, which by itself .tends
.to lengthen the loop. The combination is so de- -
sistent with maintaining the desired loop i'orni 4 signed that there is throughout the movement of (30
the guide roller a continuous change in the total
and properly guiding the il?gn. bThe1 second
k A th
pcirtant iactor is to so des gn t 8. in age
'The eìnployinent
of the loop. of the second roller
V ~ has a “fur
"the ratio oi roller moveinent to loop shorterling` ,
is substantially constant throughout the required thet advantage in that an increased wrap around
range of movement. This insures that there will the guide roller 8 is` provided for all positions oi
said guide roller. This is conduciveto more satis
not be a tight spot. The constant_ of propor
. . 4
tionality between roller movement and loop factory~ guiding.
shortening is then adjustedso that at no position ~ .\As has already been pointed out, it is desliable
will the tension be enough to cause danger of that the tensio'n on the film be as low as consist
slipping, while at the same'tìme the amount of ent with satisfactory guiding. Practicaldesign
loop shortening is reduced as far as is consistent' considerations may call for modification of the
guide roller linkage which give a nonlinear rela
› with the” permissible tension.
tion between ch'angein loop length and move.
It may not be convenient to locate theife'ed
75 “ing sprocket and pad roller as indicatedin Fig. 4. ment of guide roller. Under these conditions, the
film tension may become objectionably highwhen "
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