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Патент USA US2407797

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Sept. w, 194e.
c.' L. NELSON`
Filed Sept. 25, 1944
Patented Sept. 17, 1946
Clarence L. Nelson, Minneapolis, Minn.
Application September 25, 1944, Serial No. 555,663
7 Claims.
(o1. ses-_17)
This invention relates to a projector for show
ing a motion picture film or to a camera or other
device in which a. ñlm is progressed. As is well
Fig. 3 is a partial view in side elevation show
ing a roller used;
Fig. 4 is a partial View in vertical section illus
known in such a projector the film is Imoved past
trating said roller in another position; and
the light opening and lens, the ñlin being inter
mittently moved a certain number oi times per
second. The iilm is rnc-ved by passing over cer
tain toothed sprockets, the teeth of which engage
in perforations in the sides of the nlm. There are
Fig. 5 is a partial view in side elevation show~
ing a modification.
Referring to the drawing a portion of a moving
picture projector is shown having a frame lil on
which is mounted a barrel Il which will carry
usually one oi these sprockets below the light 10 the lens and be provided with a light opening,
opening and one above said opening. It is the uni
said barrel being secured to a head l2 secured
versal practice in disposing the nlm to have a loop
to the portion ita of the frame by headed bolts
which depends below the light opening and to
i3. The film is sho-wn as l5 and will extend
also have a loop which extends above the light
from a lower reel (not shown) past a roller lli
opening. These loops are provided to give the
carried on a tensioning arm ll c-ver a sprocket i3
necessary flexibility and freedom of movement to
at one side of which is disposed another roller
the iilm and if said loops should be suiiiciently
it engaging said film. Said nlm extends downdiminished or eliminated the iilm is apt to be
ward from sprocket It and a loop 15a is formed
broken. Such loops may also be used in cameras
therein having substantially vertical sides and
or other devices.
20 depending below sprocket I8. The nlm then ex».
It is an object of this invention to provide a
tends vertically through a guideway past the light
simple and eilicient device for maintaining the
opening and lens in barrel il, the light being
said loops in the desired form or position.
carried in the frame portion Elia at the left of
It is a further object oi the invention to pro
the ñlm as shown in Fig. 1. rI‘here is usually a
vide a device for maintaining a iilrn loop in a
vertically movable arm or claw (not shown)
motion picture projector comprising an eocentri
cally mounted member disposed in the loop and
which is reciprocated substantially parallel to the
nlm and engages the nlm in the perforations
movable by the nlm so that it will restore or form
therein. This arm acts to pull the ñlm down
the loop if the same has become diminished.
slightly in front oi the light opening and posi
It is more specifically an object of the inven 30 tion the individual picture. The film l5 as stated,
tion to provide a device for maintaining a loop
has openings lith at one or both sides and these
in a motion picture projector comprising a roller
openings often become torn or elongated and said
having a friction surface disposed in said loop
arm then cannot function properly. The nlm
with its axis substantially parallel to the axis of
after passing the member i2 extends upwardly
said loop, said roller being spaced from the end 35 and a loop itc is usually provided above mem
of said loop and eccentrically mounted with its
ber l2 and said Íllro passes from loop I 5c over
long radius disposed away from the end of said
another pulley o-r sprocket 2l and between the
loop, said roller being adapted to be engaged by
same and a roller 22. Another tensioning roller
the film. if said loop is su?liciently dirrlinished.a
23 carried on an arm 23a bears on the ñlrn and
and rotated so that its long radius will move to 40 the iilrn then passes to the upper reel. 1n the
projecting operation the reel is unwound from the
ward the end of the loop and restore the same.
upper reel, moves downwardly past the light
These and other objects and advantages of the
opening and is wound on the lower reel. Owing
invention will be fully set forth in the following
to the faulty action of the reciprocating arm
description made in connection with the accom
panying drawing in which like reference char 45 referred to and for other reasons, the loops läd
acters refer to similar parts throughout the
several views and in which:
1 is a view in side elevation of a portion of
a moving picture projector, said View being some
what diagrammatic and illustrating the travel
and position of the iilm;
Fig. 2 is a partial vertical section taken sub
and lëc and particularly läd, tend to be taken
up or to be eliminated. As above stated, if this
is permitted the film is very apt to be damaged
or broken. Usually the machine must be stopped
to readjust the loo-p.
In accordance With the present invention a
member illustrated as a ro-ller 24 is provided
which is disposed within loop |511 having its axis
stantially on line 2-«2 of Fig. 1 as indicated by
parallel to the axis of said loop. Roller 24 is
the arrows;
55 illustrated as having a bushing 25 therein having
prising a roller disposed adjacent the end of said
ilanges at the ends of said roller and being jour
loop, a member on which said roller is eccen
naled on a stud 26 shown as threaded and se
cured in the frame I0. A spring washer 21 is
disposed at one end of bushing 25 and frame l0
trically journalled, said roller normally being dis
posed witn the part of its periphery farthest
to exert a certain amount of friction on bushing
from said member remote from the end of said
25 and thus on roller 24 which is secured to bush
ing 25. Roller 25 will be made of rubber or other
material and will have a frictional surface, As
shown in Fig. 3, the surface of roller 24 may be
loop, said roller being adapted to be rotated by
said film if said loop is sufficiently diminished to
bring said part adjacent the end of said loop to
provided with knurling 24a.
restore said loop.
In Fig. 5 a roller 28 is shown, the same having
annular raised ribs 23a. These could con
veniently be formed of rubber band stretched
about the roller. A compression coiled spring 2Q
surrounds stud 26 and engages the end of bush
ing 25 to which roller 23 is secured. At its other
2. A device for maintaining a film loop in a
motion picture projector or other device com
prising an eccentrically mounted member dis
posed in said loop having its long radius remote
from the end of said loop, said member being
adapted to be moved by said film to bring its
long radius into contact with said iilm.
3. A motion picture projector or the like hav
end spring 29 engages the outer one of a pair of
ing in combination, a frame, means for moving
lock nuts 3c. Roller 28 will also be made of
a iilm, said ñlm having a loop therein, a mem
rubber or other suitable material having a fric
20 ber secured in said frame and extending into
tion surface.
said loop and having its axis parallel with the
In operation, roller 24 or roller 23 will be dis
axis of said loop, a roller eccentrically journaled
posed as shown in
i, some distance above
on said member and having a friction surface,
the bottom or end of loop iiio. Roller 24 will
said roller normally having its long radius dis~
be somewhat smaller in diameter than the dis
tance between the sides of loop läd so that nor 25 posed away from the end of said loop and adapted
to be rotated by said film to bring said long ra
mally it will not be engaged by film l5. Roller
dius into position directed toward said end.
24 is also disposed with its long radius or the
Li. The structure set forth in claim 3 and means
greater distance between the axis of stud 26 and
for exerting spring tension on said roller so that
its periphery directed upwardly or away from
the en_d of loop 55o. Should loop läd now be 30 it will remain stationary when not moved by said
taken up as frequently occurs, it will. when suffi
5. A motion picture projector having in com
ciently diminished, engage the bottom of roller
bination, a frame, a, portion having a light open
2d and due to the frictional surface of said roller,
ing therethrough, means for moving a film sub
the same will be rotated on stud 2d. When
stantially vertically past said light opening in
roller 211 is rotated its long radius is moved
cluding a sprocket, said iilm having a loop be
downwardly so that it will occupy substantially
tween said sprocket and said vertical portion, a
the position shown in Fig. li. When the long
roller disposed in said loop spaced from the end
radius is thus moved downwardly it pulls the film
thereof with its axis substantially parallel to the
downwardly and restores loop liid to its normal
position. Roller 24 will be rotated until it again 40 axis of said loop, and a member in which said
roller is eccentrically journaled supported in said
reaches the position shown in Fig. l and it will
frame, said roller normally being disposed with
then remain stationary due 'to the frictional re
its long radius directed away from said end.
sistance caused by spring washer 2l or spring 29.
6. A device for restoring a film loop in a mo
Roller 24 will remain in the position shown in
Fig. l until loop 15a again diminishes sufliciently 45 tion picture projector comprising a roller dis
posed adjacent the end of said loop, said roller
to engage it when the above described action
being eccentrically mounted and normally dis
will be repeated. It will be obvious that the in
posed witli its long radius extending away from
vention will work equally well with the upper
the end of said loop and means for retarding the
loop |50.
From the above description it will be seen that 50 rotation of said roller, said roller being adapted
to be rotated by said film if said loop is sufli
I have invented a very simple and efiicient de
ciently diminished to restore said loop.
vice for restoring and maintaining the loop in
rI. A device for maintaining a film loop in a
a motion picture film. The device is simple in
motion picture projector or other device com
construction and can be inexpensively made and
prising a member disposed in said loop and
easily and quickly installed. It will act automat
swingable about an axis, said member having one
ically to restore and maintain the loop in the
portion spaced much farther from said axis than
desired position. rEhe device has been amply
the portion at the opposite side of said axis, said
demonstrated in actual practice and found to
be very successful and eflicient.
It will of course, be understood that Various
_ member being arranged to be out of contact with
changes may be made in the form, details, ar
rangement and proportions of the parts, with
out departing from the scope of applicant’s in
vention, which' generally stated, consists in a, de
vice capable of carrying out the objects above
set forth, in the parts and combinations of parts
disclosed and defined in the appended claims.
first mentioned portion being normally disposed
What is claimed is:
1. A device for maintaining a film loop in a
motion picture projector or other device com 70
said film when said loop is of the desired size said
away from the bottom of said loop, said mem
ber being adapted to be engaged by said film and
turned about said axis when said loop becomes
sufficiently diminished in size so as to be swung
about said axis to bring said first mentioned
portion into Contact with said film to restore
said loop toits desired size.
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