US3537629A

US3537629A - Claw pulldown for cinematographic apparatus

Info

Publication number: US3537629A
Application number: US815164A
Authority: US
Inventors: Wolfgang Riedel
Original assignee: Robert Bosch Elektronik und Photokino GmbH
Current assignee: Robert Bosch Elektronik und Photokino GmbH
Priority date: 1968-04-13
Filing date: 1969-04-10
Publication date: 1970-11-03
Anticipated expiration: 1987-11-03
Also published as: DE1294806B; CH487419A

Description

United States Patent Inventor Wolfgang Iledel Wine-den, Germany Appl. No. 815,164

Filed April 10, 1969 Patented Nov. 3, 1970 Assignee, Robert leech Elelrtronlk und Photoklno G-bll Stuttgart-Unterturlrheim, Germany Priority April 13,1968

Ger-any No; 1,772,208

CLAW PULLDOWN FOR CINEMATOGRAPHIC APPARATUS 10 Claims, 4 Drawing Figs.

Int. G03b 1/22 Field of Search 226/64, 65,

v[56] References Cited v UNITED-STATES PATENTS 1 2,178,243 10/1939 Sachtleben 226/71 3,427,101 2/1969 Jorgensen et a1. 352/194X 3,460,730 8/1969 Krumbein 226/64 Primary Examiner-Allen N. Knowles Attorney-Michael S. Striker ABSTRACT: A claw pulldown for cinematographic apparatus wherein the pull down lever is rockable by a spring and a disk cam through the intermediary of a follower arm which is pivotably secured to an adjusting plate and can move its point of engagement with the pulldown lever in direction toward or away from the pivot axis of the lever to thereby change the initial angular position and/or the extent of angular displacement of the lever in-response to. each revolution of the cam. The adjusting plate for the follower arm can be provided with film guides and with a discrete light-transmitting window for each position of the follower arm.

Patented: Nov. 3, 1910 3,537,629

Shut o! 2 FIG. 2

INVENTOP S WOLFGANG RIEDEL Ll/4 f/fr his ATTORNEY Patented Nov. 3, 1970 Shoot a! 2 mvamop WOLFGANG RIEDEL hi5 ATTORNEY CLAW PULLDOWN son CINEMATOGRAPIIIC APPARATUS BACKGROUND OF THE INVENTION The present invention relates to motion transmitting apparatus, particularly to claw pulldowns for use in cinematographic apparatus. Still more particularly, the invention relates to improvements in adjustable claw pulldowns of the type wherein the initial position and the length of film transporting strokes of the claw on the pulldown lever can be adjusted to insure satisfactory transport of different types of film.

German Pat. No. 698,670 discloses an adjustable claw pulldown wherein the lever is provided with a longitudinally extending slot for a pivot pin which is adjustable by a reciprocable carriage. The latter is'movable in the longitudinal direction of the lever to thereby shift the position of the pivot pin. The lever is rocked by a crank drive and the strokes of its claw are changed when the pivot pin is caused to move lengthwise of the slot. A drawback of such claw pulldown is that its parts are subjected to considerable wear and that the unavoidable clearance between the pivot pin and the surfaces flanking the slot in the lever prevents accurate adjustments in the length of strokes of the claw.'The clearance increases in response to wear, and this also results in generation of noise which is undesirable during projection of images by a motion picture projector as well as during taking of pictures with a motion picture camera.

German Pat. No. 1,038,909 discloses a claw pulldown wherein the pin which is movable in the slot of the pulldown lever is biased against the lever by resilient means to reduce'or SUMMARY OF THE INVENTION An object of my invention is to provide a motion transmitting apparatus, particularly a claw pulldown for cinematographic apparatus,1which is simpler, more reliable, more compact and more readily adjustable than the aforedescribed conventional apparatus.

Another object of the invention is to provide a motion transmitting apparatus wherein the driven member, particularly the lever of a claw pulldown, can be adjusted with a high degree of accuracy, which produces less noise than conventional apparatus, and which can bereadily installed in presently known cinematographic apparatus.

A further object of the invention is to provide a motion transmitting apparatus wherein a rotary driving member serves to rock a pivotable driven. member and wherein the transmission of motion'from the rotary member to the pivotable member is effected in a novel and improved way.

An additional object of the. invention is to provide a novel follower structure between the disk cam and the lever of a claw pulldown for cinematographic apparatus. v

A further object of the invention is to provide a claw pulldown wherein the lever can be mounted for pivotal movement about a single fixed axis.

My invention is embodied in an apparatus for transmitting motion, particularly for effecting stepwise movements of film in cinematographic apparatus, The improved motion transmitting apparatus comprises a driving member (preferably a disk cam) which is rotatable about a first axis and has an endless cam surfacelincluding sections located at different distances from the axis, a driven member (preferably the lever of a claw pulldown in a motion picture camera or motion picture projector) which is rockable about a second axis and has a motion receiving surface spaced from the second axis (this second axis is preferably at least substantially parallel to the first axis), and follower means interposed between the two surfaces and movable between a plurality of positions in each of which the follower means engages the motion receiving surface at a different distance from the second axis so that the driven member is rocked through a different angle in each position of the follower means. Such follower means preferably comprises an arm one end of which is provided with two projections, each engaging one of the aforementioned surfaces, and the other end of which is articulately connected to a movable plate or a like device constituting an adjusting means for the follower arm. The arrangement is preferably such that the other end of the arm is turnable on a pivot which is parallel to the two axes and which is movable by the adjusting means in a plurality of directions with reference i to the second axis.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved motion transmitting apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown a portion of a cinematographic apparatus which comprises aclaw pulldown including a rockable driven member 6. This member is a onearme d lever having a claw 5 at that end which is remote from the axis of a shaft 7 on which the lever 6 pivots. A rotary driving member, here shown as a disk cam 8 which is rotatable about the axis of a shaft 9, cooperates with a follower arm 11 which extends into the space between the peripheral surface of the cam 8 and the lever 6 to rock the lever in response to rotation of the cam. A movable platelike support or film guiding device 25 constitutes a means for adjusting the position of the follower arm 11 with reference to the cam 8 and particularly with reference to the lever 6. The axes of the shafts 7, 9 are parallel to each other and to the axis of a pivot pin 12 which serves to articulately connect the left-hand end of the follower arm 11 to the adjusting plate 25. This plate has a pair of

inclined slots

32, 34 receiving pins or

posts

31, 33 which are fixed to the housing of the cinematographic apparatus and permit movements of the plate 25 and pivot pin 12 between two end positions. During such movement, the pivot pin 12 moves in several directions with reference to the shaft 7, i.e., the direction of its movement has a vertical and a horizontal component, as viewed in FIG. 1. A spring 10 or another suitable resilient element is provided to permanently bias the lever 6 against the follower arm 11 and to thereby bias the follower arm against the surface of the cam 8. This surface has several sections which are located at different distances from the axis of the shaft 9 so that the arm 11 rocks the lever 6 at least once in response to each revolution of the shaft 9 and cam 8. The spring 10 is attachedto a post We which is mounted in the housing of the cinematographic apparatus.

The adjusting plate 25 has a handgrip portion 24 and carries a pair of film guiding elements including a fixedly mounted rail 28 and a second rail 29 which is biased toward the rail 8. The

film (not shown in FIG. Dislocated in the plane of this illustration and its edges are engaged by the

rails

28, 29. The adjusting plate 25 is further provided with an elongated aperture or slot 30 for the claw of the lever'6; this claw enters a perforation of motion picture film and causes the film to advance by a step when the lever 6 turns in a counterclockwise direction but the claw is moved out of such perforation when the lever 6 is caused to turn in a clockwisedirection, or vice versa.

The purpose of the adjustable follower arm 11-will be best understood by referring 'first to FIG. 2 which shows portions of two different films, namely, of a super'eight film 1 and a double-eight film 2. Each of these films has a width of 8 millimeters. The frames of the films l, 2 arerespcctively shown at 1a, 2a and their perforations at 3 and 4, respectively.The perforations 3 of the film} are located substantially at the level of the centers of adjoining frames 1a. The distance between the centers of successive-perforations 3 is 4.23 millimeter. The perforations 4 of the film 2 are larger than the perforations 3- and the distance between the centers of successive perforations 4 is 3.81 millimeter. It will be noted that the perforations 4 are aligned with the webs 2b between the film frames 2a. It is further to be noted that the distance between the perforations 3 and the left-hand edge of the film l is less than the distance between the perforations 4 and the left-hand edge of the film 2. The distance between the relatively large frames 1a and the right-hand edge of the film 1 exceeds the distance between the relatively small frames 2a and the right-hand edge of the film 2. All of these factors must be considered in adjusting the stroke and the initial position of the pulldown lever 6 when the apparatus is converted from use with film 1 to use with film 2, or vice versa. This is achieved by the provision of the follower arm 11 and of the adjusting plate 25 which is movable to the extent and in the directions determined by the

slots

32, 34.

The right-hand end portion of the follower arm 11 is provided with two projections, namely a rounded first projection which engages the peripheral surface of the cam8 and a second projection including

rounded portions

13, 14 one of which engages a motion receiving surface provided on an intermediate portion of the lever 6. In the illustrated embodiment, the motion receiving surface is a composite surface and includes the bottom surfaces of two lateral extensions or

lugs

16, 17 on the lever 6. These lugs are located between the claw 5 and the shaft 7. The spring 1 0 biases the projection 15 against the cam 8 and simultaneously biases the bottom sur face of the lug 17 against the projection 14. The cinematographic apparatus is ready to make exposures or to project images on the film 1. After each downward stroke of the claw 5, a different frame 1a of the film I is held in registry with a light admitting window 26 of the adjusting plate 25. If the plate 25 is moved to the other end position in which the

pins

31, 33 respectively extend into the lower ends of the

slots

32, 34, the position of thewindow 26 is taken over by a smaller second window 27 whose size corresponds to that of a frame 2a on the film 2. Such adjustment of the plate 25 by way of the handgrip portion 24 brings about an appropriate angular adjustment of the follower arm 11 and lever 6 because the portion 13 of the upper projection on the arm 11 thenengages the bottom surface of the lug 16 but the lug 17 is disengaged from the portion 14. Thus, the-point of contact between the follower arm 11 and the motion receiving surface of the lever 6 is shifted in a direction away from the shaft 7 so that the stroke of the claw 6 is reduced due to the fact that the distance between the centers of successive perforations 4 is less than the distance between the centers of successive perforations 3.

The plane of the follower arm llis preferably parallel to the plane of the lever 6. As shown, the portion 13 of the upper projection on the right-hand end portion of the follower arm llis located between the pivot12 and the portion 14. The arm 11 is pivoted clockwise about the point of its contact with the surface ofthe cam 8 when the plate 25 is moved to its upper end position; during an intermediate stage of such movement of plate 25, the portion 13 engages the lug 16 and begins to pivot the lever 6 in a clockwise direction so that the lug 17 is lifted above and away from the portion'ld while the projection 15 continues to engage the cam 8. If the plate 25 is thereupon returned to the position shown in FIG. I, the arm 11 is pivoted in a counterclockwise direction whereby its portion 13 moves away from the lug 16 when the portion 14 engages with the lug 17. The stroke of the claw 5 in the position shown in FlGfl is greater than when the portion 13 engages the lug 16; therefore. the apparatus is then ready to effect intermittent transport of the film 1. The stroke of the claw 5 increases when the point of engagement between the upper projection of the arm 11 and the motion receiving surface of the lever 6 travels in a direction toward the shaft 7. g

The claw pulldown of FIG. 3 differs from the pulldown of FIG. 1 only in the configuration of the adjusting plate 19 which is not provided with film guiding means. The claw 5 of the lever 6 is located to the left of the plate 19 and this plate is provided with a handgrip portion 18 which is accessible to the operator of the cinematographic apparatus. Otherwise, the construction and operation of the apparatus of FIG. 3 are identical with those of the first apparatus. Fixed posts 20, 22 respectively extend into

inclined slots

21, 23 of the plate 19 and enable the operator to move the follower arm 11 between two predetermined end positions. FIG. 3 shows the follower arm 11 in that end position in which the lug 17 of the lever 6 engages the righthand portion 14 of the upper projection on the follower arm; therefore, the apparatus is set for transport of the film 1. In FIG. 4, the follower arm 11 is substantially parallel with the lever 6 and the portion 13 of its upper projection engages the lug 16. The claw 5 is setto transport the film 2. The arrangement is such that the claw 5 of the lever 6 shown in FIG. 3 registers with the central portion of a perforation 3 on the film 1 and that the claw 5 registers with the central portion of a perforation 4 when the follower arm 11 assumes the position shown in FIG. 4. The angular position of the cam 8 in FIG. 3 is the same as that in FIG. 4. However, the lever 6 of FIG. 4 is turned slightly in a clockwise direction with reference to the lever 6 of FIG. 3'. Such angular adjustment of the lever 6 in unchanged angular position of the cam 8 (when the follower arm 11 is moved from the position of FIG. 3 to that of FIG. 4 or vice versa) accounts for the difference in location between the

perforations

3 and 4 with reference to the adjoining frames. All this insures that a frame 10 registers accurately with the window 26 and that a frame 20 registers accurately with the window 27 when the claw 5 of lever 6 leaves the perforation at the end of its stroke.

The improved motion transmitting apparatus is susceptible of many modifications without departing from the spirit of my invention. For example, the pivotable follower arm 11 can be I replaced by a reciprocablc follower. The lower projection of the reciprocable follower then comprises two spaced portions (corresponding to portions l3, 14 of the upper projection shown in FIGS. 1, 3 and 4), and the upper projection then comprises a single portion (corresponding to the projection 15). A different portion of the lower projection engages the surface of the cam in each position of the reciprocable follower. It is further possible to provide the follower arm 11 with an upper projection which includes more than two portions if the arm 11 is movable between more than two positions.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

lclaim:

1. Apparatus for transmitting motion, particularly for effecting stepwise movementsof film in cinematographic apparatus, comprising a driving member rotatable about a first axis and having an endless surface including sections located at different distances from said axis; a driven member roclrable about a second axis and having a motion receiving surface 'lever having a claw remote from said second axis, said motion receiving surface being provided on said lever intermediate said second axis and said claw and said second axis being at least substantially parallel to ,said first axis.

3. Apparatus as defined in claim 1, wherein said follower means comprises first and second projections each of which engages one of said surfaces, and further comprising adjusting means for moving said follower means between said positions to thereby move said projections with reference to the correspondingsurfaces.

4. Apparatus as defined in claim 3, wherein at least one of said projections comprises a plurality of portions, one for each position of said follower means, said adjusting means being arranged to maintain a different portion of said one projection in contact with the respective surface in each position of said follower means.

5. Apparatus as defined in claim 4, wherein said follower means comprises an; arm which is provided with said projections and wherein said adjusting means comprises means for changing the angular'position of said arm in response to movement of the follower means between said portions thereof.

6. Apparatus as defined in claim 1, wherein said follower means is arranged to change that angular position of said driven member which corresponds to a given angular position I of said driving member when said follower means is moved between said positions thereof.

7. Apparatus as defined in claim 1, wherein said follower means comprises an. arm and further comprising adjusting means for moving said arm between said positions thereof,

said adjusting means comprising a movable support and pivot means articulately connecting said arm to said support.

8. Apparatus as defined in claim 7, wherein said driven member comprises a pulldown lever and wherein said support is provided with film guiding means.

9. Apparatus as defined in claim 1, further comprising means for biasing said motion receiving surface against said follower means. i

10. Apparatus as defined in claim 9, further comprising adjusting means for moving said follower means in several directions with reference to said second axis, said second axis being at least substantially parallel to said first axis.