WO1992022490A1 - Mecanisme d'entrainement intermittent ou variable - Google Patents

Mecanisme d'entrainement intermittent ou variable Download PDF

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Publication number
WO1992022490A1
WO1992022490A1 PCT/US1992/005154 US9205154W WO9222490A1 WO 1992022490 A1 WO1992022490 A1 WO 1992022490A1 US 9205154 W US9205154 W US 9205154W WO 9222490 A1 WO9222490 A1 WO 9222490A1
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WO
WIPO (PCT)
Prior art keywords
pulley
mechanical drive
pulleys
sprocket
drive
Prior art date
Application number
PCT/US1992/005154
Other languages
English (en)
Inventor
Martin S. Mueller
Original Assignee
Mueller Martin S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mueller Martin S filed Critical Mueller Martin S
Publication of WO1992022490A1 publication Critical patent/WO1992022490A1/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B1/00—Film strip handling
    • G03B1/18—Moving film strip by means which act on the film between the ends thereof
    • G03B1/20—Acting means
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B1/00—Film strip handling
    • G03B1/18—Moving film strip by means which act on the film between the ends thereof
    • G03B1/20—Acting means
    • G03B1/24—Sprockets engaging holes in the film

Definitions

  • Motion picture film consists of a series of separate images spaced along a strip of film. In order for the images to be captured by a camera or projected onto a screen, a mechanism that
  • the film advance cycle effected by such a system comprises a film dwell phase, during which a frame of film is stopped at a film gate so that film exposure or projection can occur, and a film advance phase, during which the film is
  • the film drive mechanism currently used in motion picture cameras is a claw mechanism. It comprises a movable arm with
  • the claw mechanism works adequately for conventionally formatted film advanced at the usual speed (i.e., 35 mm. film having four perforations per frame and advancing at 24 frames per second)
  • the size and weight constraints of the claw mechanism become more significant when larger film formats and/or higher film advance speeds are desired.
  • Such higher film speeds are needed for slow-motion photography, and when scale models (i.e. miniatures) are used for special effects.
  • the increase in film size requires a larger claw arm, and thus a larger and heavier camera.
  • Such larger-format film has more sprocket perforations per frame, and in addition it is desirable for this type of film to have a larger number of sprocket perforations engaged with the claw mechanism during film advance in order to minimize the localized stress on the film. But the larger number of sprocket pins needed on the claw arm to accomplish this adds additional mechanism, and thus more weight, to the camera.
  • the geometry of the claw arm also limits the acceleration and deceleration imparted to the film, and thus the claw mechanism is difficult to operate efficiently at high speeds. In addition, the claw arm is difficult to counterbalance, and at higher speeds this results in vibration which can affect the photographic quality of the images.
  • the type of film drive mechanism currently used with motion picture film projectors is a Geneva star, a well known expedient for effecti: intermittent drive operation which has many applications apart from motion picture film projectors.
  • the Geneva mechanism comprises a constantly rotating shaft and an intermittently rotating shaft. Each turn of the constantly rotating shaft causes a partial turn of the intermittently rotating shaft and its attached film sprocket, followed by a period during which that shaft and film sprocket are held in a fixed position.
  • the Geneva mechanism also has limitations. For example, the rate of acceleration and deceleration imparted to the film, as well as the advance and dwell time, are limited by the geometry of the Geneva mechanism.
  • the Geneva mechanism is impractical for high frame rates, and also for reverse operation. Although it is capable of operating in the reverse direction, such use in a film drive requires pushing instead of pulling the film, and that fact makes reverse operation less accurate and less reliable.
  • the Geneva mechanism also is not capable of high- speed rewind or fast forward without disengaging the film from the drive.
  • the Geneva mechanism is less reliable when using the larger-format films because greater masses of film and larger sprockets exceed the practical torque limitations of the mechanism.
  • There are a variety of other mechanical applications which also require intermittent or inconstant motion, and which could benefit from the use of a drive mechanism that overcomes the limitations of Geneva star drives and other prior-art expedients.
  • the drive of this invention comprises input and output pulley means, drive belt means continuously engaging the pulley means, and means for periodically discoordinating the movement of the drive belt means relative to the output pulley means to cause the latter to rotate inconstantly.
  • Shafts and other rotating devices such as film sprockets, may be attached to each of the pulley means to deliver continuous rotation as well as inconstant rotation.
  • the effective diameter of the output pulleys may be increased or decreased in relation to the input pulley means to achieve either a reduction or an increase in the output angular velocity, thus achieving the effect of changing the output gear ratio.
  • the discoordinating means operates by expanding and contracting a pair of drive belt loops in complementary fashion to periodically decouple the rotation of the input pulleys from that of the output pulley means.
  • Cam-driven idler pulleys are preferably employed for accomplishing the belt loop expansion and contraction function.
  • the cam profile may be selected to achieve intermittent output motion, or continuous output motion at periodically varying speed, or even intermittently reversing output motion.
  • An intermittent drive in accordance with this invention can be used as a film drive mechanism for a motion picture camera or projector to intermittently advance film past a film gate for cinematic exposure or projection or both.
  • a film sprocket is attached to each of the intermittently rotating and constantly rotating output shafts so that the intermittent shafts cause their attached film sprockets to advance the film intermittently while the continuous shafts cause their attached film sprockets to advance the film continuously.
  • Complementary film storage loops buffer the temporary mismatch between continuously and intermittently advancing segments of the film.
  • the advantages of the invention are especially significant in connection with such motion picture film drives.
  • the invention avoids the need for the conventional claw and Geneva mechanisms, thus permitting the construction of smaller cameras and projectors and avoiding all the other limitations associated with the claw and Geneva mechanisms.
  • the teeth on the rotating sprockets which advance the film engage a larger number of the film perforations and, therefore, minimize the localized stress on the film. Because the stress on the film is reduced, larger-format films and higher film advance speeds can be used.
  • the invention also provides a novel mechanism for driving and synchronizing a register pin assembly to achieve precise positioning of the film at the film gate during exposure or projection. It comprises a pivoting linkage mechanism, a pin arm mechanism connected to the linkage by a connecting arm, a cam assembly that causes pivoting of the linkage mechanism, and detent means to control the motion of the intermittent film sprockets.
  • the pin arm mechanism has register pin means engageable with the film perforations, and detent pin means engageable with the detent means.
  • the cams are mounted on the continuously rotating sprocket drive shafts, and the detent means are mounted on the intermittently rotating sprocket drive shafts.
  • Another feature of the invention is a clutch mechanism which selectively disconnects the intermittent drive train and operates the film at a constant speed for fast forward and reverse operation.
  • This mechanism employs rotatable, translatable clutch dog means which are splined to, and slidable on, a power transmission shaft. The clutch dog moves between one operating position in which it transmits power to the idler pulley cams, and another operating position in which it cuts off the power to those cams, thus causing the mechanism to run constantly instead of intermittently.
  • Fig. 1 is a perspective view, schematic in nature, of a basic embodiment of a cinematic film drive mechanism in accordance with this invention
  • Fig. 2 is a series of seven schematic diagrams labeled A through G respectively, which illustrate successive stages in the translation of the idler pulley and idler arm components, and in the relative displacements of the other pulley components, of the film drive mechanism of Fig. 1
  • Figs. 3A and B are plots, along the time (or phase) axis, correlated with the successive operating stages of Fig.
  • FIG. 4 is a more detailed perspective view of an embodiment of a similar film drive mechanism, with parts broken away to reveal details of construction, and also showing a novel register pin assembly in accordance with the invention;
  • Fig. 4A is a sectional view, taken along lines 4A-4A of Fig. 4;
  • Fig. 4B is a perspective view of a preferred form of one of the detent discs shown in Fig. 4;
  • Fig. 5 is a side elevation view of a motion picture camera drive incorporating the film advance mechanism of Fig. 4 with parts cut away to reveal details of the register pin assembly;
  • Fig. 6 is a front elevation view of the motion picture camera drive of Fig. 5 with the added structure of a vacuum plate assembly, and with parts cut away to reveal details of the register pin assembly;
  • Fig. 7 is a top plan view, schematic in nature, of pulley, idler arm, cam and cam-follower components of a drive mechanism in accordance with a further embodiment of the invention incorporating means for adjusting the rotational alignment and rotational relationship of the intermittently rotating pulley components, and means for counter-balancing the pivotal motion of the idler arm mechanism;
  • Fig. 8 is a partial sectional view taken along line 8-8 of
  • Fig. 9 is a top plan view of keeper shoe components used to thread and secure film in a motion picture camera that incorporates the film drive mechanism of Figs. 1 or 4, with parts broken away to reveal details of the vacuum plate assembly;
  • Fig. 10 is a partial side elevation view of a clutch mechanism for disengaging the cam components from the continuously rotating shaft of the film drive mechanism of Fig. 1, thereby allowing the normally intermittently rotating sprockets to rotate continuously when desired, as for example during rapid rewind or fast forward of the film;
  • Fig. 11 is a sectional view taken along line 11-11 of Fig. 10;
  • Fig. 12 is a top plan view, schematic in nature, of the constantlyrotatingpulley, intermittently rotating pulley, drive belt, and idler pulley components of a mechanical drive in accordance with an embodiment of the invention which achieves one revolution of the intermittently rotating pulleys for each revolution of the constantly rotating pulleys;
  • Fig. 13 is a view similar to Fig. 12 but showing a speed- reduction drive in accordance with another embodiment of the invention that achieves one half revolution of the intermittently rotating pulleys for each revolution of the constantly rotating pulleys;
  • Fig. 14 is a view similar to Fig. 12 but showing a speed- increase drive in accordance with another embodiment of the invention that achieves two revolutions of one intermittently rotating pulley and one and one half revolution of another intermittently rotating pulley for each revolution of the constantly rotating pulleys;
  • Fig. 15 is a view similar to Fig. 12 but showing a speed- reduction drive in accordance with another embodiment of the invention that achieves one-half revolution of one intermittently rotating pulley, and one-third revolution of another intermittently rotating pulley, for each revolution of the constantly rotating pulleys;
  • Fig. 16 is a top plan view, schematic in nature, of a pair of film drives in accordance with a further embodiment of the invention which are incorporated into a motion picture film duplicating device;
  • Fig. 17 is a perspective view, schematic in nature, of a mechanical drive in accordance with a further embodiment of the invention which may be used in various devices not related to motion picture film;
  • SUBSTITUTE SHEET Fig. 18 is a perspective cut-away view of a motion picture film camera that incorporates the film drive of Fig. 1 or Fig. 4;
  • Fig. 19 is a perspective cut-away view of a motion picture film projector that incorporates the film drive of Fig. 1 or Fig. 4.
  • FIGs. 1-3 schematically illustrate the structure and operation of a basic embodiment of a mechanical drive in accordance with the invention which takes the form of a mechanism 10 for advancing a motion picture film.
  • the film which is designated 16, comes off a film supply reel 12, winds around a pair of film guides 15, and returns to a take-up reel 14.
  • Film 16 conventionally comprises a series of sprocket perforations 18 adjacent each of its longitudinal boundaries.
  • the film drive mechanism 10 comprises a sprocket assembly 20, a pair of constantly rotating shafts 22, 24, a pair of intermittently rotating shafts 26, 28, a pulley assembly 30, a cam and follower ' assembly 32, and a drive motor 34, which may be a conventional electric motor, continuously rotating shafts 22 and 24.
  • Drive motor 34 is preferably connected directly to shaft 22, and shaft 22 is interconnected with shaft 24 by a timing belt (i.e. toothed belt) 500 and a pair of toothed drive pulleys 502, 504, so that the single drive motor can drive both shafts 22, 24 in positive synchronism.
  • Sprocket assembly 20 comprises a pair of constantly rotating sprockets 36, 38 and a pair of intermittently rotating sprockets 40, 42.
  • Each sprocket 36-42 comprises a series of teeth 44
  • SUBSTITUTESHEET extending around its circumference near each of its ends, which teeth are adapted to engage respective series of film perforations 18.
  • the number of perforations 18 for each frame of film is equal to the number of teeth 44 extending around the circumference of each sprocket 36- 42, so that each revolution of the sprockets advances one frame of the film; but it is also possible to use a smaller or larger number of teeth so that the sprockets rotate more or less than one revolution per film frame.
  • Each of the constantly rotating sprockets 36, 38 is mounted to one of the constantly rotating shafts 22, 24 respectively, and each of the intermittently rotating sprockets 40, 42 is mounted to one of the intermittently rotating shafts 26, 28 respectively.
  • Pulley assembly 30 comprises a continuous-loop drive belt 46, a pair of constantly rotating pulleys 48, 50, a pair of intermittently rotating pulleys 52, 54, a pair of idler arms 56, 58, each of which is pivotally mounted at one end on a respective pivot 64, and a pair of idler pulleys 60, 62 mounted at the free ends of the idler arms 56, 58 respectively.
  • Each of the constantly rotating pulleys 48, 50 is mounted to one of the constantly rotating shafts 22, 24 respectively, and each of the intermittently rotating pulleys 52, 54 is mounted to one of the intermittently rotating shafts 26, 28 respectively.
  • drive belt 46 is internally toothed, and constantly rotating and intermittently rotating pulleys 48-54 are provided with external teeth which engage with the drive belt teeth.
  • the cam and follower assembly 32 comprises a pair of cams 66, 68 mounted to constantly.rotating shafts 22, 24 and a.pair
  • idler arms 56, 58 are preferably biased apart by a compression spring 63 which may be mounted on two short stub shafts (not visible) protruding from respective idler arms 56, 58 and each extending a short distance into the interior of the compression spring 63 at the respective opposite ends thereof.
  • the cam followers 70, 72 could be driven by a single cam instead of the pair of cams 66, 68 illustrated herein; and in that case the compression spring 63 could be replaced by a solid connection between the idler arms 56, 58.
  • another approach would be to provide a single idler arm (instead of the illustrated pair of idler arms 56, 58) to mount both idler pulleys 60, 62, and to provide a single cam and a single cam follower to drive the single idler arm; in which case the issue of a connection between idler arms would be irrelevant.
  • drive belt 46 connects all four pulleys 48-54, and thus all four shafts
  • the pulleys 48-54 are provided with marks (designated X) to enable the reader to trace the progression of angular positions of these pulleys through the successive operating phases of the mechanism illustrated by Figs. 2A through 2G respectively. Quite remarkably, as the reader can tell from an examination of the successive positions of those marks in these successive operating phases, the intermittently rotating pulleys 52, 54 do not always rotate through the same angular displacement as do the constantly rotating pulleys 48, 50 from one operating phase to the next. Therein lies one of the unique features of the present invention. The explanation for this unique mode of operation is as follows. Fig.
  • FIG. 2A shows that idler arms 56, 58 are displaced from constantly rotating pulley 48 and intermittently rotating pulley 52, a condition referred to as top dead center, and labelled "TDC" in Fig. 3A.
  • Shafts 22, 24 are being rotated counterclockwise at a constant speed by the motor 34, causing pulleys 48, 50, cams 66, 68 and constantly rotating sprockets 36, 38 to also rotate counterclockwise at the same speed. This rotation is indicated by arrows 55 in Figs, l and 2A.
  • Pulleys Pulleys
  • the belt 46 also imparts the same counterclockwise rotation, at the same angular velocity, to intermittently rotating pulleys 52, 54 and their corresponding intermittently rotating shafts 26, 28 and intermittently rotating sprockets 40, 42. This rotation is indicated by arrows 61 in Fig. 2A.
  • each of the pulleys 48-54 is connected to a corresponding sprocket 36-42 respectively by a corresponding shaft 22-28 respectively, each sprocket rotates at the same instantaneous rate as its corresponding pulley.
  • pulleys 48, 50, shafts 22, 24, and sprockets 36, 38 rotate continuously at a constant speed
  • pulleys 52, 54, shafts 26, 28, and sprockets 40, 42 rotate intermittently.
  • Film dwell is therefore experienced by the portion of the film 16 which is located between the intermittently rotating sprockets 40, 42 when the latter sprockets stop rotating.
  • ilm advance occurs in this region at a higher linear
  • Figs. 1, 18 and 19 illustrate how the film 16 should be arranged prior to operation. In the embodiment of Fig.
  • the film 16 should extend from the film supply reel 12 around one of the guide rollers 15, continuously rotating sprocket 38, intermittently rotating sprocket 42, intermittently rotating sprocket 40, continuously rotating sprocket 36, and the other guide roller 15, and then back to fil"-- take-up reel 14.
  • the free loops of film 74, 76 should be formed between constantly rotating and intermittently rotating sprockets 36, 40 and between constantly rotating and intermittently rotating sprockets 38, 42 respectively in order to provide the film slack which is required to allow for intermittent differences in the rates of linear advance of different portions of the film during the operation of the film advance mechanism.
  • the sizes of the loops 74, 76 will change as needed to accommodate the film acceleration and deceleration caused by intermittent rotation of the constantly rotating sprockets 36, 38. Specifically, free loop 74 increases in size .during deceleration of the intermittent sprockets and decreases in size
  • Fig. 18 shows film 16 loaded in a motion picture camera 78 employing a supply reel 12A and take-up reel 14A which are coaxially located
  • Fig. 19 shows film 16 loaded in a motion picture projector 79 employing a non-coaxial pair of reels 12B and 14B for supply and take-up respectively.
  • Figs. 4-6 constitute a more detailed showing of a film drive mechanism 10A in accordance with the invention, which incorporates a modified pulley assembly 30A.
  • the film drive mechanism 10A has many of the same components identified in connection with the film drive mechanism 10 of Fig. 1 and is nearly identical in operation to the film drive mechanism of Fig. 1, a fact which is indicated by the use of similar reference numerals distinguished only by the "A" suffix.
  • Idler arms 56A, 58A each comprise three tiers 100, 102, 104, each mounted on pivots 64A, and a pair of connecting stub shafts 108 connecting these tiers at their opposite ends, thereby defining a first channel 110 between tiers 100 and 102, and a second channel 112 between tiers 102 and 104.
  • a compression spring 63A is housed within telescoping tubes 65 and 67 mounted on the stub shafts 108 (see Fig. 4A) .
  • Each cam follower 70A, 72A is mounted to one of the idler arms 56A, 58A respectively within the first
  • each idler pulley 60A, 62A is mounted to one of the idler arms 56A, 58A respectively within the second channel 112 thereof.
  • cams 66A, 68A and cam followers 70A, 72A define a common plane which extends through first channels 110
  • idler pulleys 60A, 62A, pulleys 48A-54A and drive belt 42A define a common plane which extends through the second channels 112.
  • the continuously rotating components comprise shaft 22A and the components mounted thereon (sprocket 36A, pulley 48A and cam 66A) and shaft 24A and the components mounted thereon (sprocket 38A, pulley 50A and cam 68A) .
  • the intermittently rotating components comprise shaft 26A and the components mounted thereon (sprocket 40A and pulley 52A) and shaft 28A and the components mounted thereon (sprocket 42A and pulley 54A) .
  • a register pin assembly 80 in accordance with this invention is preferably included to provide precise positioning of the film 16 during film dwell.
  • the register pin assembly generally is desirable to insure image steadiness in motion picture camera applications, but may, if desired, be omitted in whole or in part.
  • the register pin assembly 80 comprises a linkage 130, a connecting arm 132, a register pin arm mechanism 134, a pair of cams 136, and a pair of detent discs 138, each comprising a detent notch 139.
  • Linkage 130 extends in a direction generally perpendicular to shafts 22A-28A and has cam followers 140 rotatably mounted on the respective opposite ends thereof. Each cam follower 140 is received within a cleft formed
  • Linkage 130 also comprises a slot 142 through which a connecting arm 132 extends. Within the slot 142, a first end of connecting arm 132 is connected to linkage 130 by means of a spherical bearing (not visible) secured by a pivot pin 144.
  • the spherical bearing which is a well known commercially available component, allows the connecting arm 132 freedom of movement over a conically shaped range.
  • Register pin arm mechanism 134 comprises a shaft 135 which is mounted for rocking rotation about a horizontal axis 137.
  • the shaft 135 is journaled in the side walls of a housing 133 in the manner illustrated by Fig. 6.
  • On this shaft 135 are mounted a pair of register pin arms 148, a first detent pin arm 150, and a second detent pin arm 152.
  • Detent pins 154 engageable with detent notches 139 of respective detent discs 138, are located on the first and second detent pin arms.
  • Register pins 158 engageable with film perforations 18 , are located on each register pin arm 148.
  • a second end 132B of connecting arm 132 is received within a slot 145 formed in the arm 134 and is connected thereto by another spherical bearing (not visible) secured by a pivot pin 146, the spherical bearing again allowing the arm 132 a conical range of movement within the slot 145.
  • Cams 136 are mounted on shafts 22A, 24A in the same horizontal plane as cam followers 140, and cooperate therewith to rock the linkage 130 horizontally about its vertical pivot 141.
  • detent discs 139 are mounted on shafts 26A, 28A
  • each register pin arm 148 has a plurality of register pins 158 as seen in Fig. 5, in order to minimize local stress on the film 16A.
  • the cams 136 rotate the linkage 130 counterclockwise about the vertical pivot 141, thrusting the connecting arm 132 forward, and thereby causing the register pin arm mechanism 134 to rock in the opposite direction about its shaft 135 and axis 137.
  • This causes the register pins 158 to be retracted rearwardly and thus to disengage from the film perforations 18A, allowing film 16A to advance to the next frame position.
  • the detent pins 154 are withdrawn from the detent notches 139, permitting a resumption of rotation of detent discs 136 and thus of shafts
  • the register pins 158 alternately engage the film in order to positively lock the film 16A in position during film dwell, and then release during film advance.
  • the register pins 158 are inserted into the film perforations 18A.
  • the detent pins 154 are also inserted into the detent notches 139 to momentarily prevent rotation of shafts 26A and 28a, and thus temporarily prevent any change in the angular position of the intermittent sprockets 40A, 42A.
  • Figs. 5 and 6 are detailed illustrations of the film advance mechanism of Fig. 4, and they also include certain features not seen in the latter figure. In particular Figs.
  • FIG. 5 and 6 include an upstanding film gate 124 which supports the film 16A from the front, and is formed with a frame window 117 (see Fig. 6) through which each frame of film can be exposed or projected.
  • these figures also illustrate a film back plate 120 (visible through the frame window 117 in Fig. 6) which cooperates with the film gate 124 to form a film throat 113 through which
  • this back plate 120 is provided with a film vacuum back feature, also not seen in Fig. 4, which serves to clamp the film against the back plate 120 during film dwell, holding it flat and positioning it precisely in the desired focal plane for sharpness of focus over the entire area of the frame window 117.
  • the film backing plate 120 comprises a plurality of individual air ducts 122 fed by surface slots 119 and internal conduits 121 which are connected to a suitable vacuum source, thus creating the necessary suction at the film plane for holding the film flat during exposure.
  • FIG. 5 An additional feature seen in Figs. 5 and 6 is the fact that the lower ends of the vertical shafts 22A-28A are journaled in the floor of the housing 133, and their upper ends are journaled in horizontal bridge structures 111, also visible in Fig. 9.
  • Figs. 7 and 8 illustrate two adjustment features which are especially useful in a projector application.
  • One such feature which may be employed with the embodiment of the invention shown in Fig. 1, is a means for adjusting the rotational alignment of the intermittently rotating pulleys 52A, 54A when framing the film.
  • the adjustment means is in the form of a mounting block 180 comprising two ends, a plurality of elongated slots 182, 184, and a center slot 186 adapted to receive an eccentric cam 188 which is provided with a screw-driver slot.
  • Each of the pivots 64A is fixed to one end of block ISO at the top of respective idler arms 56A, 58A.
  • the elongated slots 182, 184 are adapted to receive respective fasteners such as clamping screws 190, 192.
  • the second adjustment feature illustrated in Figs. 7 and 8, which may be used with both the Fig. 1 and Figs. 4-6 embodiments of the invention, is a means for adjusting the rotational relationship between the intermittently rotating pulleys 52A, 54A.
  • An elongated bar 200 is provided which has a pair of rollers 202, 204 rotatably mounted to respective opposite ends of the bar, a pair of elongated slots 206, 208, and a center slot 210 adapted to receive an eccentric cam 211 provided with a screw-driver slot.
  • the elongated bar 200 overlies a fixed supporting plate 201 which is located in the region surrounded by the drive belt 46 or 46A, and the eccentric cam 211 is journaled on the supporting plate 201 by a pin 203.
  • the bar 200 extends across the space between the continuously rotating pulleys 48, 50 or 48A, 50A and the intermittently rotating pulleys 52, 54 or 52A, 54A so that roller 202 is in contact with the outside of the drive belt 46 or 46A at a location between the constantly rotating pulleys 48, 50 or 48A, 50A; and roller 204 is in contact with the outside of the drive belt at a location between the intermittently rotating pulleys 52, 54 or 52A, 54A.
  • Elongated slots 206, 208 are adapted to receive respective fasteners 212, 214, which are preferably clamping screws threaded into the supporting plate 201. Because
  • the fasteners 212, 214 may be received at different locations along the lengths of their respective slots, depending on the rotational position of the eccentric cam 211.
  • rotation of the eccentric cam 211 provides a way of sliding the bar 200 between its solid-line and dashed-line positions of Fig. 7.
  • roller 204 flexes the drive belt 46 or 46A the belt from its dashed-line position to its solid-line position of Fig. 7.
  • Such means are preferably in the form of a set screw 520, which fastens pulley 50 or 50A to shaft 24 or 24A.
  • Similar set screws 530 only one of which is shown in Fig. 4B, should also be used with the embodiment shown in Figs. 4-6, to fasten detent discs 138 to their shafts 22A, 24A so that the angular relationship between the discs and those shafts can be selected in a like manner.
  • Each set screw 530 is
  • the eccentric cam 211 When the projector is used for film which has not undergone any shrinkage, the eccentric cam 211 is turned back to its original position, causing the bar 200 and rollers 202, 204 to return to their dashed-line positions, and allowing the belt 46 or 46A to return to its dashed-line position, which restores the original angular relationship between the intermittent pulleys 52, 54 or 52A and 54A.
  • a pair of counterbalance mechanisms 280 designed to counter the weight shift resulting from the pivoting of idler arms 56, 58 or 56A, 58A which occurs during every cycle of operation of the film advance mechanism.
  • the counterbalance mechanisms 280 each comprise a counterweight 282, a balance arm 284, and a link 286 connecting the balance arm to the adjacent one of the idler arms 56A or 58A.
  • Each balance arm 284 is mounted upon a respective pivot pin 288, thereby permitting the balance arms to pivot in synchronism with their respective idler arms 56A, 58A. Because of the connection provided by the links 286, the pivoting of idler arms 56A, 58A causes a corresponding pivoting of the balance arms 284, causing counterweights 282 to move in a direction generally opposite to the direction of the idler arms, and thereby maintaining the center of mass of the system at a constant location, and thus avoiding undesirable vibration.
  • keeper shoes 220 may be provided or retaining the film 16 or 16A in engagement with the sprockets 48-54 or 48A-54A during operation of the film drive mechanism.
  • Each of the shoes 220 is pivotably fastened to the floor of the housing 133 by a pin 224.
  • the keeper shoes are engaged during camera or projector operation, but may be rotated to a disengaged position (as shown by the broken lines in Fig. 9) when threading or removing the film.
  • Figs. 10 and 11 further means, illustrated in Figs. 10 and 11, are provided for switching intermittently rotating shafts 26, 28 or 26A, 28A and their sprockets 40, 42, or 40A, 42A to continuous rotation. Since the mechanism performs intermittent motion only when the idler arms 56, 58 or 56A, 58A are in pivotal motion, and that pivotal motion is driven by the cams 66, 68 or 66A, 68A, it follows that sprocket motion can be changed from intermittent to continuous by disengaging those cams from the continuously rotating shafts 22, 24 or 22A, 24A.
  • the disengagement means comprises respective manual control levers 230, respective sleeves 232 which are integral with cams 66 and 68 respectively or 66A and 68A respectively and rotatable therewith about shafts 22 and 24 respectively or 22A and 24A respectively by means of respective pairs of ball-bearings 233, respective clutch dogs 234 which encircle the respective sleeves 232, respective lock dogs 236 which are fixed to respective projector frame components 237 and each of which comprises a pair of diametrically opposite locking bosses 238, and respective drive dogs 240 each of which comprises a pair of diametrically opposite driving bosses 242, and is mounted on respective constantly rotating shafts 22 and 24 or 22A and 24A, and is pinned thereto by a respective pin 241 for rotation therewith.
  • Each sliding clutch dog 234 is splined to its respective sleeve
  • Each sliding clutch dog 232 also comprises a pair of diametrically opposite locking notches 244 adapted to engage with diametrically opposite locking bosses 238 when respective cams 66 and 68 or 66A and 68A are disengaged from shaft 22 or 24 respectively, and a pair of diametrically opposite driving notches 246 adapted to engage the diametrically opposite driving bosses 242 when the respective cam is engaged with the respective shaft.
  • Each control lever 230 is pivotally mounted on its respective frame component 237 by a respective pin 231, and is forked so that it terminates in two spaced tines 230A and 23OB (see Fig. 11) .
  • These tines embrace the sliding clutch dog 234, and are provided with respective connecting pins 239 which are loosely received within a channel 234A formed circumferentially about the clutch dog 234.
  • the clutch mechanism illustrated in Figs. 10 and 11 is that which is necessary to engage and disengage only one of the cams 66, 66A or 68, 68A; so it must be duplicated for the other one of those cams.
  • the two clutch mechanisms must be operable in synchronism, for example by ganging their control levers 230 in any suitable, conventional manner.
  • Figs. 12-15 illustrate how the invention can be modified to change the effective gear ratio of the intermittent drive mechanism by changing the relative diameters of any of the pulleys 48, 50, 52, 54 or 48A, 50A, 52A, 54A.
  • Fig. 12 illustrates a drive mechanism of the type previously discussed, where the diameters of all the intermittently rotating pulleys 52, 54 and the constantly rotating pulleys 48, 50 are equal, and therefore the total rotational output of each intermittently rotating pulley is equal to the total rotational input to the constantly rotating pulleys.
  • Fig. 14 shows a pulley system where one of the intermittently rotating pulleys 54C is one half the diameter of the constantly rotating pulleys 48, 50, and the other
  • intermittently rotating pulley 52C is two-thirds the diameter of the constantly rotating pulleys.
  • the output achieved by the Fig. 14 arrangement is two rotations of intermittently rotating pulley 54C and one and one half revolution of the intermittently rotating pulley 52C for each revolution of the constantly rotating pulleys.
  • Fig. 15 shows a pulley system where the diameter of one of the intermittently rotating pulleys 54D is twice the diameter of the constantly rotating pulleys 48, 50, and the diameter of the other intermittently rotating pulley 52D is three times the diameter of the constantly rotating pulleys.
  • the output achieved by the Fig. 15 arrangement is one-half revolution of intermittently rotating pulley 54D and one-third revolution of the intermittently rotating pulley 52D for each revolution of the constantly rotating pulleys 48, 50.
  • Fig. 16 shows the application of a film drive mechanism in accordance with this invention to a cinematic film duplicating machine 300.
  • the duplicating machine comprises generally four film reels 312A and B, 314A and B, two film drive mechanisms 310A and B, a light source 301, a dark enclosure 317, and an exposure gate 313.
  • An original film 316A to be duplicated is threaded from supply reel 312A to take-up reel 314A through a film drive mechanism 310A of the type illustrated in Fig. 1, which comprises two intermittently rotating sprockets 340A, 342A and two continuously rotating sprockets 336A, 338A.
  • a blank, unexposed film 316B within the dark enclosure 317 is similarly transferred from supply reel 312B
  • SUBSTITUTE SHEET to take-up reel 314B through another film drive mechanism 310B of the type illustrated in Fig. 1, which comprises two intermittently rotating sprockets 340B, 342B and two continuously rotating sprockets 336B, 338B.
  • the film drive mechanisms 310A and B intermittently advance the films 316A and B respectively past the exposure gate 313, where the images of the original film 316A are copied frame by frame onto the duplicate film 316B.
  • Fig. 17 illustrates a mechanical drive train 400 in accordance with the invention which is incorporated in a non-cinematic apparatus.
  • the drive train 400 comprises a pair of continuously rotating pulleys 448, 450 associated respectively with drive shafts 422, 424, a pair of intermittently rotating pulleys 452, 454 of different diameters associated with output shafts 426, 428 respectively and driving respective output devices 427, 429, and a cam assembly 432 comprising idler arms 456, 458 carrying respective cam followers 470, 472 which respond to cams 466, 468 respectively driven by shafts 424, 422 respectively.
  • shafts 422 and 424 are interconnected by a toothed timing belt 500 and a pair of toothed drive pulleys 502, 504 which mate therewith so that a single motor attached to shaft 422 or 424 can drive both shafts in positive synchronism.
  • the idler arms 456, 458 also carry idler pulleys 460, 462, which produce differential motion of a drive belt 446 when the idler arms 456, 458 and idler pulleys 460, 462 are oscillated by
  • Fig. 17 achieves intermittent rotation of rotating devices 427, 429 in the same manner as the embodiment of Fig. 1, the similarity of operation being highlighted by the use of reference numeral for corresponding parts which have the same last two digits.
  • differenti ⁇ .. rotational velocities are also achieved as explained above in connection with Figs. 12-15.
  • the profiles of the cams 66, 68 in Fig. l could, if desired, be designed to cause the output pulleys 52, 54 to slow down but not to stop entirely.
  • the invention comprises a power transmission belt (such as the continuous-loop drive belt 46) which is somehow manipulated in such a way as to periodically increase and decrease the linear speed of portions of the belt during power transmission operation.
  • the drive belt may be configured to
  • SUBSTITUTE SHEET form a pair of buffer loops (designated LI and L2 in Fig. 2A) which expand and contract in a complementary fashion, i.e., one of them expands as the other contracts, and vice versa.
  • There may also be a mechanism such as the pair of continuously rotating pulleys (48, 50), which drive the mechanism, and which cooperate to form the drive belt buffer loops LI and L2, and a pair of output pulleys (such as the inconstantly rotating pulleys 52, 54) , which provide power output and also cooperate to form the drive belt buffer loops LI and L2.
  • the drive mechanism of this invention is also useful for driving strip media other than motion picture film.
  • Magnetic tape transports for example., for audio, video or data applications, might employ a drive mechanism in accordance with this invention in an application which requires an inconstant read-out speed.
  • this invention provides a general-purpose drive mechanism which is useful in cinematic apparatus and a variety of other applications for converting continuous rotation into intermittent or inconstant rotation in a more efficient and advantageous manner than prior art expedients, and in addition is capable of gearing the average output speed up or down as required.

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  • General Physics & Mathematics (AREA)
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Abstract

Mécanisme (10 ou 10A) servant à effectuer l'entraînement intermittent ou variable dans des dispositifs divers, y compris une caméra ou un projecteur de cinéma. Dans une application cinématique, le mécanisme d'entraînement peut faire avancer de façon intermittente un film cinématographique (16 ou 16A) pour la prise de vue, la projection , ou bien pour les deux. Ledit mécanisme comprend une paire de poulies d'entrée (48, 50 ou 48A, 50A) qui tournent en continu, une paire de poulies de sortie (52, 54 ou 52A, 54A) qui tournent de façon variable, et un ensemble constitué d'une couronne d'entraînement (46 ou 46A), de poulies folles (60, 62 ou 60A, 62A) et de contre-cames (66, 68, 70, 72; ou 66A, 68A, 70A, 72A), servant à créer un décalage périodique du mouvement de boucles d'amortissement (40 ou 40A) formées par la courroie d'entraînement (46 ou 46A) de façon que les poulies de sorties (50, 52 ou 50A, 52A) tournent de façon intermittente ou variable. Des arbres (22, 24, 26 et 28 ou 22A, 24A, 26A et 28A) et des tambours à ergots (36, 38, 40 et 42; ou 36A, 38A, 40A et 42A) sont entraînés par chacune des poulies d'entrée et de sortie, une paire de tambours à ergots (36, 38 ou 36A, 38A) tournant continuellement et une paire de tambours à ergots (40, 42 ou 40A, 42A) tournant de façon intermittente.
PCT/US1992/005154 1991-06-19 1992-06-18 Mecanisme d'entrainement intermittent ou variable WO1992022490A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US71767191A 1991-06-19 1991-06-19
US717,671 1991-06-19
US89333292A 1992-06-03 1992-06-03
US893,332 1992-06-03

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WO1992022490A1 true WO1992022490A1 (fr) 1992-12-23

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017113731A1 (de) * 2017-06-21 2018-12-27 Herma Gmbh Aufwickelvorrichtung zum Aufwickeln eines Bands

Citations (7)

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Publication number Priority date Publication date Assignee Title
US3451637A (en) * 1967-10-30 1969-06-24 Ampex Differential pressure web transport
US3613978A (en) * 1969-10-07 1971-10-19 Walter Renold Apparatus for intermittently moving film
US4183068A (en) * 1978-08-31 1980-01-08 Cipher Data Products, Incorporated Magnetic tape transport mechanism
US4765117A (en) * 1986-08-07 1988-08-23 Kureha Chemical Industry Company Limited Apparatus for welding a strip of tape to film
US4777513A (en) * 1987-10-09 1988-10-11 The Mead Corporation Web transport system
US4778093A (en) * 1987-04-13 1988-10-18 Walter Renold Film transport assembly
US4886199A (en) * 1987-07-10 1989-12-12 Bergwerk-Und Walzwerk-Maschinenbau Gmbh Strip drive for advancing materials for processing

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451637A (en) * 1967-10-30 1969-06-24 Ampex Differential pressure web transport
US3613978A (en) * 1969-10-07 1971-10-19 Walter Renold Apparatus for intermittently moving film
US4183068A (en) * 1978-08-31 1980-01-08 Cipher Data Products, Incorporated Magnetic tape transport mechanism
US4765117A (en) * 1986-08-07 1988-08-23 Kureha Chemical Industry Company Limited Apparatus for welding a strip of tape to film
US4778093A (en) * 1987-04-13 1988-10-18 Walter Renold Film transport assembly
US4886199A (en) * 1987-07-10 1989-12-12 Bergwerk-Und Walzwerk-Maschinenbau Gmbh Strip drive for advancing materials for processing
US4777513A (en) * 1987-10-09 1988-10-11 The Mead Corporation Web transport system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017113731A1 (de) * 2017-06-21 2018-12-27 Herma Gmbh Aufwickelvorrichtung zum Aufwickeln eines Bands
US10968064B2 (en) 2017-06-21 2021-04-06 Herma Gmbh Winding device for winding up a ribbon or web

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