US2819069A - Internal drag roller - Google Patents

Description

W. R. 1159M 19,09

I INTERNAL DRAG ROLLER Filed May 25, 1.955 2 Sheets-Sheet 1 INVENTOR.

/1 TTORNEY "Jan; 75,1958 W. R. ISOM 29,819, 9

INTERNAL DRAG ROLLER Filed May 25, 1953 2 Sheets-Sheet 2 INVENTOR;

D IZI/ JI 1?. [10/]? ATTORNEY United States Patent INTERNAL DRAG ROLLER Warren R. Isom, West Collingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application May 25, 1953, Serial No. 356,940

Claims. (Cl. 271-25) This invention relates to film advancing apparatus, and particularly to a damping unit used in obtaining a constant and uniform film speed at a sound translation point.

Film drive systems for sound recording and reproduction, wherein a drive sprocket is used for advancing perforated film, are well-known. These systems generally have a film-pulled drum with a flywheel on its shaft and .a tensioned filter in the loop between the sprocket and drum. In such systems, it has been found desirable to introduce friction or a drag at some point in the mechanism. For instance, felt friction pads on the sound drum ball bearings have been used, as well as friction applied directly to the flywheel on the drum shaft. Further more, various frictional devices have been applied to the pressure roller. However, in all these instances, this type of frictional application does not completely solve the problem.

Other forms of damping have been in the form of eddy current brakes on the flywheel or a viscous drag on the flywheel by running it in oil or Water. It was found that viscous resistance gave better results, because it contributed to the damping of the system. Adding a resistance of any nature to the flywheel or sound drum had two important bad effects. One was to limit the effectiveness of the flywheel, and the other was to cause slippage of the film on the sound drum. These two effects limited the usefulness of this method of applying damping, even though it proved that viscous friction was preferred over mechanical friction.

The present invention avoids these two bad effects by applying a viscous friction to the pressure roller which holds the film on the sound drum. By the use of silicon oil, which is not subject to viscosity changes with temperature within the range of temperatures to which it is subjected, and placing this oil within the pressure roller, not only the amount of drag obtained can be controlled by varying the viscosity of the silicon, but also this drag may be controlled by the amount of clearance or space provided within the roller for holding the silicon oil. The application of viscous friction by the pressure roller causes no slippage between the drum and the film. Also, because the resistance or drag is at the pressure roller, the additional tension in the film more tightly binds the film to the sound drum, and thereby makes the flywheel more effective as a film stabilizing factor.

Furthermore, since there is suflicient tension in the film loop between the sprocket and sound drum, the resilient filter in the loop can be damped so as to eflectively minimize oscillation in the over-all system. The invention is particularly adaptable for introducing viscous friction in a loose loop film path of film recorders and reproducers at the pressure roller so that the advantages of a tight loop system can be incorporated in a loose loop system and still preserve all of the inherent advantages of the loose loop system.

The principal object of the invention, therefore, is to facilitate the constant and uniform advancement of film.

2,81%,fifiti Patented Jan. 7, 1958 ice Another object of the invention is to provide an improved constant and uniform film advancing drive mechanism.

A further object of the invention is to provide an im-' proved damping element for a constant speed film advancing mechanism.

Although the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the appended claims, the manner of its organization and the mode of its operation will be better understood by referring to the following description, read in conjunction with the accompanying drawings, forming a part hereof, in which:

Fig. 1 is an elevational view of a film drive mechanism embodying the invention.

Fig. 2 is a cross-sectional view of one modification of a damping pressure roller used in the system of Fig. l, and

Fig. 3 is a cross-sectional view of another modification of the damping pressure roller shown in Fig. 2.

Referring now to Fig. 1, a film drive system is mounted on a mounting plate 5, which may be part of a picture projector. A film 6 may come from a supply reel or from the intermittent advancing mechanism of a picture projector. It passes in a loop over guide roller 7, over a stabilizing drum 8, which has a flywheel on its shaft, then into an 8 loop around filter rollers 10, over a film advancing sprocket 11 with its shoe 12, and then to a holdback sprocket 14 with its shoe 15. A portion of an optical sound reproducing assembly is shown at 17. The shoes and other elements are mounted on the plate 5 in the usual manner, such as by screws 9 and 13.

The jockey or filter roller unit 18 having rollers 10 is of the type disclosed in Bartelson U. S. Patent No. 2,685,417 of August 3, 1954. In brief, this unit comprises the rollers 10 mounted on the diametrically opposite ends of a sector-like plate 20 fixed to a rotatable shaft 21 on the other end of which is wound a spring encased in a housing filled with oil, preferably silicon. The movable plate 29 has an arcuate, elongated slot 22 therein for reception of a fixed pin 23, the slot and pin acting as a limiter for the movement of the rollers 10.

The film 6 is in a tight loop between the sprocket 1i. and the drum 8, and the tightness is controlled by the adjustment of the tension applied to the filter rollers 10. The film is in a loose loop as it approaches roller 7 and contacts the drum 8. Mounted adjacent the drum 8 and applying pressure to the film thereon in any suitable manner, such as by a spring, is a pressure roller 25 having a rubber or neoprene tire 26 thereon (see Fig. 2). The rollershown in Fig. 2 has a sleeve bearing, while the roller shown in Fig. 3 has roller bearings.

Referring now to Fig. 2, the roller is formed of an inner cylindrical member 28 mounted on an arm 29 by a screw 30. The member 28 has radial holes or openings 32 and an annular recess 33 in the outer central portion of its cylindrical wall. Mounted for rotation on the member 28, is a cylindrical bearing member 35, on one end of which is a guide flange 36 having a recessed cylindrical portion for supporting the tire 26. The remaining element of the roller is an outer flange 40, which has a lip 42 fitted into the member 35 so that centering will be maintained. The flange 4t is attached by screws 41 to the cylinder 35. Before flange 40 is assembled, the central portion of the roller is filled with silicon oil 44. The oil in this reservoir passes through the openings 32 to the outer recess 33, where it exerts a viscous drag on the rotating elements of the roller, and thus provides the improved viscous friction mentioned above.

Referring now to Fig. 3, this roller construction has a central cylindrical member 50 attached to an arm 51 by a screw 52. -At the ends-fof a narrowef'diameter section of the member 50 are mounted ball. bearings 57 and .58, which are properly located axially by spacer 73 and secured by screw 75. A rotatable cylinder 61 is mounted onthe bearings, on the-right-hand .end of Which .is a guide flange 62. Thecentral portion of the cylinder- 61 is recessed to accommodate a tire 63, which maybe of neoprene orrubber similar to the tirei26 shown in Fig; 2.

"This rollerin Fig; 3 has an-outerlflange 65 with. a lip 66, which is fitted into the cylinder for centering and for making secure the ball .bearings 57 and 58, the flange being attached to cylinder=61 by screws 67. Similarly to the roller shown in Fig. 2,. silicon oil 69 isplaeed at" the center of the roller before thefl-ange 65ais assem bled. This oil passes: through. openings 77nand 79 ,and time the clearance 71 betweenythetspacer 73 and-the cylinder 61. The oil, which is also in thenbearingsy57-and 58, introduces to the rotatinglportions-of the roller-a Niseous resistance which has been found to .providei-thetsnecessary drag discussed above, thereby-prov-i-dinga loose-sloop constant speed film drive systern withthe advantagesof a tight loop system.

. A feature ofithe above .constru ctionis'the mannerin which the silicon oilis heldwvithin'the rollers. T-he fit at 81 between the member 28=and flange -36-permi-ts -free running of theflange, but close-enough soithat the clearance is bridged by theoiliwhich is held in place by surface tension. This provides. a.staticcapillaryseabwhen the roller is at rest, :the fiuid-eventually flowing or draining .back into the reservoir. When the roller is running, the, diiferencein velocity between the insidesurface-of the cylinder 35. and the outer .surface of: cylinderfZS as at point. 85, reduces .the pressure. 1 at the point 181 as the flow of oil is fromthe center .ofuthe roller to the outside thereof. Thisproduces as'dynamic velocityseal against leakage when the roller :is operating.

Theseztypes' of sealing actions are-also presentin the roller bearing roller ofFig: 3. wln this construction, the difierence in velocity is produced. by the difference between the diameter of the small shouldenof member 50 and the diameter of the inner racesof the ball bearings 57 and 58. i

I claim:

1. In a film'drive system having a drive sprocket for pulling film over an inertia drum, a drive sprocket,-an inertia drum, a tensioning means between said sprocket and drum, said film being adapted to :approachsaid'drum in a loose loop and pass over saidtensioning means to said sprocket in a tight loop, a pressure roller, means for supporting said roller for-movement into and-out-of contact with said drum, said roller being adapted to contact film passing over saididrum, and means within said roller for applying a uniform internal viscous drag to the surface of said roller and a resistance :to'the passage of film over said drum, said viscous drag means including a fixed inner cylinder and, anouten'cylinder rotata'blewith respect to said innercylinder.

2. A film drive system inaccordance with claim 1 in which saidtensioning means between said sprocketand said drum forms an S path for film adapted to pass between said sprocket and drum.

3. A film drive system'in accordance with; claim 1. in

4 which silicon oil is provided between said cylinders'to provide said viscous drag.

4. A viscously damped roller comprising a fixed hollow cylindrical member, a second cylindrical hollow member surrounding and rotatable with respect to said fixed cylindrical member, oil within said fixed member, a space be ing provided between said fixed member and said rotatable member, said fixed member having centrally located openings thereinto .permitsaid oil tofiowstherethrough into said space., and a cl'osurernember for one end of said rotatable member for holding said .oil insaidlfixedmember and centering said rotatable member 'thereon.

5. A viscously damped roller in accordance with claim 4 in which saidrotatablamember:has.a guide ilange at one end thereof, said closure-memberforrning a guide flange at the other end of said rotatable member, and an antislip tire around the central portion thereof.

6. A viscously damped roller in accordance with claim 5 in which said oil is silicon.

-7. A damping roller comprising. a central fixed cylindrical member, ball bearings mountedon and adjacent the ends ofsaid member, a rotatable member mounted on said ball bearings, oil within the central portion of said fixed member, and openings-in said first mentioned member for pass'ingoil within saidmember to said ball bearings.

8. A damping roller in accordance with claim 7,in which guide flanges are 'mounted at the ends of said rotatable member and an anti-slip tire is over the central portion of said rotatable member.

9. A damping roller iiraccordancewith claim 7, in which said oil is silicon.

10. A viscously damped roller comprising a fixed hollow cylindrical. member havinga cylindrical wall and one end open, asecond hollow cylindrical member surrounding and rotatable-With respect to :said fixed cylindrical member and having one end open, oil Within said fixed member, said fixed member having an annular recess in the outer central portion of its cylindrical wall and openings therein passing through said cylindrical wall fromthe interior of said fixed member to said recess, and a closure member for the open ends of' said cylindrical members for holding said oil in said fixed member and centering said rotatable member thereon.

.References Cited in the file of this patent UNITED STATES PATENTS 1,998,931 Kellogg, Apr..- 23, .1935 2,099,376 ,Shapiro Nov. 16,1937 2,112,894 Hasbrouck Apr. 5, 1938 2,157,393 Black May 9, 1939 2,206,380 Zimmerman July 2, 1940 2,417,282 Wheeler ,a-Mar. 11, 1947 2,499,210 -Bartelson Feb. 28, 1950 2,586,600 B.artelson Feb. 19, 1952 2,618,370 Orwin. Nova 18, 1952 2,622,707 Faus Dec. 23, 1952 2,685,417 Bartelson Aug. 3, 1954 FOREIGN PATENTS 136,834 Australia Mar. 17, 1950 414,642 Great Britain Aug. 7, 1934

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