Патент USA US2407797код для вставки
Sept. w, 194e. c.' L. NELSON` v í¿407,795 DEVICE FOR MAINTAINING FILM LOUPS Filed Sept. 25, 1944 h , :Erm/enfor CLARaNcE i.. NELSON Patented Sept. 17, 1946 2,407,795 UNITED STATES PATENT OFFICE ’2,407,795 DEVICE FOR MAINTAINING FILM LOOPS Clarence L. Nelson, Minneapolis, Minn. Application September 25, 1944, Serial No. 555,663 7 Claims. (o1. ses-_17) l This invention relates to a projector for show ' 2 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 2,407,795 4 3 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. 10 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 nlm. 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. CLARENCE L. NELSON.