US1047528A - Motion-picture apparatus. - Google Patents

Description

G. F. JENKINS.

MOTION PICTURE APPARATUS.

APPLIGATION FILED MAY 1o, 1911.

Patentd Dec. l?, 1912.

of the expensive film while also causing unpleasant results 1n the pictures on the screen SHINGTON, DISTRICT OF COLUMBIA.

CHARLES FRANCIS JENKINS, 0F WA 4i union.

MOTXGN-PICTURE APPARATUS.

Specification of Letters Eatent.

Patented Dec. 1?, 1912.

Application led May 10, 1911. Serial No. 626,396.

To all whom it may concern:

Be it known that I, CHARLES; FRANCIS JENKiNs, a citizen of the United States, residing at lVashin'gton, in the District of Columbia, have invented certain new and useful 'improvements in Motion-Picture Apparatus, of which the following is a specifi.d cation, reference being had therein to the accompanying drawing.

This invention 'relates to devices for avoiding serious tension upon moving picture film as it is rewound after leaving the projecting apparatus. Practically it is found necessary to wind the films which are often many hundreds of feet in length, but as the film is delivered at a constant rate by the projecting d evices and as the roll upon the drum necessarily increases in diameter the film rlrum necessarily tends to take 'up the film more and more rapidly, the rate with long films increasing many fold. Obviously this must be compensated or the use of the method is impossible. A common expedient is to drive the winding drum by devices allowing slip of the. parts whenever a low tension upon the film is exceeded. But as the roll increases. this slip-causing tension acts through anincreasing lever arm always equal to the radius of the growing roll, and hence the pull necessary to cause slipping at one stage of the winding is many times that required at another time, whence it follows that during a part of the winding period, it being impracticable to vary the force needed to produce slipping, there is undesirable tension upon the film. Film is at best short lived, and since tension upon it is principally exerted in pulling the film edges, at two perforations, against the faces of two narrow sprocket drum teeth, such tension as has been described seriously 'shortens'the life as soon as any. wear or injury results.

To provide a simple and convenient means for avoiding` the difficulty is the object of this invention, and this object is attained by providing devices which automatically wind the film at precisely the rate of its delivery no matter what the diameter of the roll.

ln the accompanying drawings, Figure 1 is a side elevation of a portion of a projecting apparatus involving my novel devices.' Fig. 2 a detail view of a portion of the roll driving devices.

In these figures,

A represents a suitable a similar gear H support, B the casing of a portion of common projecting apparatus provided with a lens C and a driving crank D, and C the casing for the film winding drum D mounted upon a shaft E. Upon this shaft is also fixed a large disk F. One of the shafts of 'the film feeding apparatus within the casing B, for example the shaft X of the usual lower sprocket drum, projects from the casing and bears a bevel gear H which engages extending downward alongside the disk, parallel thereto and at a short distance therefrom. The shaft is mounted in any suitable bearings, as J, J. Upon the central portion of this shaft is splined a small pref. erably rubber faced wheel or roller K the edge of which presses firmly against the disk and the hub of which bears, in an annular groove, a loose but nonerotating ring L to which is pivoted one end of a link M. The other end of this link is pivoted to the free end of a rigid arm N fixed to a rock shaft O mounted in the casing or in a support therein. This shaft bears a second rigid arm I in the plane of the film roll and having at its free end a roller P, to rest upon the periphery of the latter against which it is held by gravity alone, usually.

The film strip Q, passes out of the casing B, around suitable rollers R, R, and to the film drum, upon which the roller I at first rests while the point of contact of the wheel K upon the disk lies in line with a surface elementof the drum. The proportion of the parts is such that the wheel K rotates the disk and drum shaft just fast enough to take up the film delivered by the projecting apparatus. As the film winds upon the drum, increasing its diameter and the length of film wound at each turn, the roller I is pushed away from the drulns axis, rocking the shaft and swinging the other arm, thus pushing the wheel upward on its shaft where it travels in a larger circle on the disk and thus moves the drum through a smaller angular distance for each of its own rotations. The rate of rotation of the drum is thus in inverse proportion to the circun'lference of the roll and, whatever the diameter' of the i flier, the film is wound as fast as it is delivi red and without lbeing injuriously pulled against the sprocket teeth of the film feeding devices within the casing B. In other words, the devices secure a slight, practii` liy constant, ined uniform tension upon a slender shaft l upon the film coming from the projecting devices.

What I claim is:

l. The combinuiion 'with a projecting nm-A ehine und a film box alongside the Saineyof a Iilni drum mounted in the box, a, friction disk niounied on the drinn shaft, a Shaft in geared connection with seid nia-chine 'and proif'ided 'r'.f'il'li a drum-driving friction roller. impinging on said disk and arranged o elide' on' the shalt Withoutf rotating thereon, and Lwo rigidly connected pivored mn'is.,

one normally pressingto-ward the periphery Iof the drum sind the other connected ily e link to said roller to lSlide the seine on irs shaft.

2. The eoinbinalion with u projecting mi chine having im external rot-ating gear, of a film box, a ilin drum mounted in the loo'Xj a friction dislon the drinn sli-ufr., e roel;- shafty immllel io die drum simil, an arm projecting from the roclsha't and having n terminal roller normally resting on lilie druin, a second erin projecting' from the rockslmfl, a link pivoially connected to rile .free end of the leiter arm, simil; parallel 'lo a diameter of the diel and provided with a pinion e1 j ig said gear, i friction roller sliding' on lie slmft, rotating herewith, in f fonlacl; Willi Smid disk, and revolulily connected 'lo (he ifree end of said link, substantially as Sei, ilforlli..

ln teei'imoirr whereof? I aliX my signature in presence el' lire Witnesses CHARLES FR ANGS JENKLNC; Witnecsee:

JAMES L. CRAWFORD, R..- CRAIG GREENE.

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