US2210372A

US2210372A - Speed stabilizing device for sound record films

Info

Publication number: US2210372A
Application number: US275676A
Authority: US
Inventors: Kolb Otto Kurt
Original assignee: BRITISH ACOUSTIC FILMS Ltd
Current assignee: BRITISH ACOUSTIC FILMS Ltd
Priority date: 1938-06-13
Filing date: 1939-05-25
Publication date: 1940-08-06
Anticipated expiration: 1957-08-06

Description

Aug. 6, 1940.

0. K. KOLB Filed May 25, 1959 Fig. 1.

Inventor; 0 66- by Attorney t uzi ml T 2.210372 UNITED STATES PATENT; OFFICE 1 srannis'rammzmo' DEVICE FOR SOUND I a EG W S Otto'Kurt Kolb, chiswick liondon, Eng imamsigner to British Acoustic im filed,"

,London, England, a British-company I Application May 25.1939. Serial Nee-15,676

I 1 in Great Britain June-13, 8

This invention relates to devices'tti or use in rigidly attached to the drum. shaft which-is film feeding mechanisms for the purpose o irenk power-driven through an elastic coupling, the dering the speed of film feed as constantas p'os said box containing the heavy; flywheel sible at the point at which sound recording is which is carried round by fluid friction, but effected, or at which sound reproduction by there. are difilculti'es in constructing such a de- 5 photo-electric means takesplace. vice in a simple and effective form. The inner;

It has long been known that if a film on which flywheel is relatively heavy and must be accua sound record is to ,be made or from-which a rately balanced while being carried unreliable soundrecord is to-be rep'roducedis taken round antiefriction bearings within the hollow shell, a drum so as to embrace an appreciable arc or and the'clearances must be correctly adjusted 10 the periphery of this, and if the film is driven to provide the necessary degree of couplingbeby suitable means so that in turn it drives the tween shell and flywheel. Yet again, in connec drum in the manner of a belt, and if associated. tion with the'shafts of high speed engines and with-the drum mechanically there is a flywheel, the like in which many of the present problems the eflect "of this system is' to add inertia to the do not arise, it has been proposed to fix a hollow 16 film (which in itself is virtually without mass) drumtothe shaftand to use liquid in'the drum to and this arrangement serves to maintain the damp torsional vibrations andto increase the film .velocity at the recording or reproducin internal surface by the provision of inwardlypoint, substantially constant. projecting fixed gills or vanes.

i 20 The film is generally deflected out of a straight According to the present invention, a flywheel m path on one or both sides of its point of conhaving acomparatively light hollow shell or tact with the drum by elastic means either incontainer is carried by the shaft of the film druin herent inthe film itself or separately applied which is driven solely by the film itself, the shell thereto, whereby vibratory speed changes imhaving no internal bearings or loose parts,-but

8b parted to the film by or through the driving v containing a liquid of high viscosity which pro- 5' mechanism are not applied to the drum or are .vides the necessary damping effect. In such an reduced in intensity-so that the inertia of the arrangement, the viscous liquid absorbs energy drum system prevents speed changes being presto varying degrees throughout its mass with ent in the portion of a film passing the sound changes of velocity, and pick-up of the flywheel '80 reproducing or recording point. If the system, mass is gradual in starting as ls-desirable for .comprising thefiywheel; film-driven drum and avoiding excessive. film stresses. The liquid -film form a mechanical oscillatory-system, speed should 'be of high density so as to keep. the size fluctuations known ashunting can .be set up, of the casing as small as possible. The'casing and will seriously interfere with the recording *can be light and indeed it may be of material 88' and reproduction of the sounds, but by the use' 10W p fi gravitykfli has only act as of suitable damping 'means applied eitherto the Conta and for transmitting the q e 0 flywheel system or to the-elastic means referred and from the liquid. The damping'in the liquidto such hunting effects and consequent fiuctuais very efifective and makes it possible to use less tions in the film speed can be largely eliminated. total mass for the fl wheel, so that t e compli- 40 Any-system having a substantial flywheel mass ance of thefilm acting through the curved por- 4o rigidly attached to the drum over which th fil tions is increased, andthe efilciency of the system passes has the further disadvantage that in as a filter for eliminating transient disturbances starting up quickly, the film is subjected to conis improved. siderable tension in accelerating the flywheel up It is ou d a e Stabilizing effect o fiY-' to its normal speed and this leads to film breakwheel constructed according to the invention, 45

ages. V becomes more considerable as the total mass of Various proposals have been made for overthe flywheel syste t n limits, redllced acoming the difllculties mentioned above. In f l t0 the moment O inertia} 6f t e Viscous some cases, it was suggested to divide the fiyliquid and dampingfactol 1 the v sc s ty wheel massinto two parts coupled by fluid fric- Of that q d- With p i m l e- 50' tion or by electromagnetic drag, and this may .tween these factors; the compliance of the film provide the required damping but still leaves the acting thro h the ved portions or loops is film subject to considerable starting loads. increased owing to the reduction of the tension Other proposals which overcome this latter difii-, of the film necessary for driving 1 the flywheel '65 culty involve the-useof a thin-walled hollow box and maintaining it insteady i'irmtion. Cruise'- quently, the effectiveness of the flywheel system as a mechanical filter in eliminating transient disturbances, is improved.

As no internal mechanical hearings or loose parts requiring accurate clearances are provided, the construction is substantially simplified.

In order that the invention may be clearly understood and readily carried into efiect, one form .of construction in accordance therewith will now be described merely by way of example, with reference to the accompanying drawing,,in which:

form of flywheel die and drum; and 3 Figure 2 is a side elevation of the flywheel with its drum and the associated parts.

Figure l is a czfitral sectional elevation of one th the associated driving spin- The shell or container of the flywheel is a" drum. [2 over which the sound record film passes,

and by means of which alone, the whole flywheel system can be spun or rotated. The spindle l l is carried on the practically frictionless ball bearings l3 and I4. Two filling holesare formed in small bosses I5, I 6 secured in the flat wall of the dished piece 2, a liquid-tight joint being made in each case, for example by riveting. The holes are closed by two screwed plugs ll, l8.

It is intended that the shell or container 2, 3 shall be filled with a viscous liquid, which may be glycerine or a mixture of glycerine and water or other solvent, or it may be a thick oil such as castor oil, or a viscous solution such as sugar syrup, cellulose esters or ethers in solvents, and so forth. The specific gravity of glycerine is 1.26 and its viscosity is about 8.5 poises at 20 C. .The viscosity of castor oil is suflicient for the purpose, but its density is a little belowunity so that a larger bulk of castor oil is needed for the flywheel action. As the efliciency of the damping action depends on the viscosity, it is desirable to use a liquid which has a; viscosity of the order of say '5 poises at the working temperature, say 20 C. and the greater the density of the liquid the better for the purpose in view. In some forms of the apparatus, in order to-increase the damping, an additional partition or septum 6 may be provided lying ina plane of rotation and secured.

to the rim at the joint 4, and, indeed, more than one such partition may be provided.

The partition is perforated at l to allow of circulationofthe viscous liquid and to allow the shell to be easily filled, but instead, there may be a central aperture in it around the hub or boss 8. Instead of being fixed to the outer shell, the partition 6 may be carried by the central hub or boss 8 in which case, a circular space is left between the outer edge of the partition 6 and the casing l.

As seen in Figure 2 the driving drum I2 is provided with a freely-turning pressure or lay-on roller l9 and around it, the film 20 passes. A feed sprocket 2| carries the film towards the drum l2 and the film 20 is drawn at substantially constant speed over and around said drum by the sprocket 22. Owing to the very small tractive force required to maintain the drum and flywheel in motion, well defined

loops

23 and 24 form in the film 20 which having great elasticcompliance in conjunction with the inertia and damping of the flywheel system serves very completely to eliminate velocity variations in the travel of the film 20 at the recording or reproducing point.

It is obvious that various small modifications may be made in the construction; for example, although it is not of importance if the casing is slightly distorted by centrifugal forces, the pieces 2, 3 may be stiffened or rendered more rigid,'for example, by radial ribs attached to the inside or outside of the flat faces of the pieces 2, 3 or bymeans of circular corrugations.

Iclaim: 1

1. In a feeding mechanism for sound record films, the combination of a drum around which the film passes and driven solely by the film itself, a speed-stabilizing flywheel in driving relationship with said drum and comprising a container and a viscous liquid within said container constituting substantially the whole of the flywheel mass.

2. In a feeding mechanism for sound record films, the combination of a shaft, a drum secured to said shaft around which drum the film passes and which is driven solely by the film itself, a speed-stabilizing flywheel also secured to said shaft and comprising a container and a viscous liquid within said container constituting substantially the whole of the flywheel mass.

3. In a feeding mechanism for sound record films, the combination of a drum around which the film passes and driven solely by the film itself, a speed-stabilizing flywheel in driving relationship with said drum and comprising a light thin-walled container and a viscous liquid within said container constituting substantially the "films, the combination of a shaft, a drum secured to said shaft around which drum the film passes and which is driven solely by the film itself, a speed-stabilizing flywheel also securedto said shaft and comprising a container of material of low specific gravity, and a viscous liquid within said container constituting substantially the whole of the flywheel mass.

6. In a feeding mechanism for sound record films, the combination of a shaft, a drum secured to said shaft around which drum the film passes and which is driven solely by the film itself, a speed-stabilizing flywheel also secured to said shaft and comprising a container and a liquid within said container, said liquid having a high viscosity exceeding 5 poises constituting substantially the whole of the flywheel mass.

7. In a feeding mechansm' for sound record films, the combination of a drum around which the film passes, means for positively forwarding the film whereby said drum'is solely driven by the pull of the fihn itself, a speed-stabilizing flywheel in driving relationship with said drum and in said container constituting substantially the whole of the flywheel mass.

8. In a feeding mechanism for sound record films, the combination of a drum around which the film passes, means for positively forwarding the film whereby said drum is solely driven by the pull of the film itself, a speed-stabilizing flywheel in driving relationship, with said drum and comprising a container, at least one partition located internally of said container and fixed to the wall thereof and a viscous liquid within said container and in contact with said partition constituting substantially the whole of the f ywheel mass.

9. In a feeding mechanism for sound record films, the combination of a shaft, a drum secured to said shaft and around which the film passes, means for positively forwarding the film whereby said drum is solely driven by the pull of the film, a speed-stabilizing flywheel 'also secured to said shaft andcomprising a light thin-walled cylindrical container, at least one partition located internally of said container in a plane transverse to the axis thereof and fixed to said container to rotate therewith and a viscous liquid within said container and in contact with said partition constituting substantially the whole of the flywheel mass.

10. In a feeding mechanism for sound record films, the combination of a shaft, a drum secured to said shaft and around which the film passes, means for positively forwarding the filml whereby said drum is solely driven by the pull of the film, means for forming the film into two loops, one of said loops preceding and the other following the passage of the film over said drum, a speedstabilizing flywheel in drivingrelatio'nship with said drum and comprising a container and a viscous liquid within said container constituting substantially the whole of the flywheel mass.

11. In a feeding mechanism for sound record films, the combination of a shaft, a drumsecured to said shaft around which drum the film passes and which is driven solely by the film itself, a speed-stabilizing flywheel also secured to said shaft and comprising a container and a viscous liquid within said container, said liquid having a density high in comparison with that of water constituting substantially the whole of the flywheel mass.

- O'I'IO KURT KOLB.