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WO1993006520A1 - Procede et appareil destines a la realisation et a la projection d'un film - Google Patents

Procede et appareil destines a la realisation et a la projection d'un film Download PDF

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Publication number
WO1993006520A1
WO1993006520A1 PCT/CA1992/000397 CA9200397W WO9306520A1 WO 1993006520 A1 WO1993006520 A1 WO 1993006520A1 CA 9200397 W CA9200397 W CA 9200397W WO 9306520 A1 WO9306520 A1 WO 9306520A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
projector
rate
projection
gaps
Prior art date
Application number
PCT/CA1992/000397
Other languages
English (en)
Inventor
Michael A. Gibbon
David M. Martindale
Original Assignee
Imax Corporation
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 Imax Corporation filed Critical Imax Corporation
Publication of WO1993006520A1 publication Critical patent/WO1993006520A1/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

Definitions

  • This invention relates generally to a method of producing and displaying a motion picture, and to an apparatus for use in the method.
  • An image projection rate of 48 frames per second is usually sufficient to overcome objectionable flicker but there remain some other objectionable artifacts due to the fact that only 24 unique frames are shown per second.
  • One of these artifacts is an objectionable "doubling" of images when an observer follows an object in motion across the screen. The severity of this artifact depends upon the velocity of the motion depicted in the scene. Cinematographers can usually avoid this artifact by planning their shots to minimize high speed motion within scenes.
  • Another artifact is the blurring of the edges of an object in motion. This is due to the fact that when a scene is filmed at a low frame rate (e.g.
  • the shutter in the camera is open for a long enough time for an object in motion to be recorded on the same film frame in different positions resulting in an indefinite position of the object on the film frame.
  • the edges of the object are blurred with the amount of blurring proportional to the speed of the object in motion.
  • a rolling loop film transport mechanism the film is transported through a film passage defined between a curved stator and a rotor.
  • the rotor has gaps in which loops of film are continuously formed as the rotor rotates.
  • the loops are developed as the respective gaps travel from a film inlet location to an aperture.
  • the loops then decay progressively as the gaps travels from the aperture to a driven output sprocket.
  • the film is laid onto registration pins at the aperture and an image is projected from a frame which is stationary at the aperture.
  • the next loop lifts the film from the registration pins and positions the next frame for projection.
  • Each gap in the rotor is provided with an angled plate that acts as a shutter to block light each time the gap passes the aperture.
  • the plate is curved to accommodate the film loops that form in the gap.
  • the rotor has eight gaps and rotates at 180 rp , which translates to a frame rate of 24 fps.
  • each frame is in fact projected twice by providing so-called “flicker shutters" between each two successive primary shutters (in the rotor gaps). This provides an effective image projection rate of 48 fps.
  • An object of the present invention is to provide an improved method and apparatus for producing and displaying a motion picture, which addresses these considerations.
  • the method of the invention is applicable to the production and display of a motion picture which includes a plurality of scenes.
  • the method includes the steps of selecting at least two different film frame rates for recording those scenes, predetermining for each scene one of the selected frame rates and recording each scene on film at the frame rate that was predetermined for that scene.
  • the motion picture is subsequently displayed by projecting the film using at least one projector which is capable of being operated at at least two different projection frame rates corresponding to the frame rates used for recording.
  • the projector is controlled so that the film is continuously projected while varying the film projection rate to cause each scene to be projected at a frame rate related to the frame rate at which the scene was recorded.
  • the "related" projection frame rate will be the same as the rate at which the scene was shot.
  • the projection rates could vary with respect to the shooting rates, for example, by a predetermined constant amount (e.g. 5%). Where special effects such as slow motion or fast motion are required, * greater variations are possible.
  • a fast action scene in a motion picture can be shot at a high frame rate (e.g. 48 fps) while the other scenes are shot at a lower rate (e.g. 24 fps).
  • a high frame rate e.g. 48 fps
  • the other scenes are shot at a lower rate (e.g. 24 fps).
  • the fast action scene is projected at the higher frame rate while the lower rate is used for the remaining scenes.
  • the desirable higher resolution is achieved for the fast action scene and the additional amount of film used corresponds only to the portion of the film for which higher resolution is necessary.
  • the term "scene” as used herein is intended to mean a defined episode or sequence within the motion picture. That episode or sequence need not be recorded using the same camera or on a continuous piece of film but will involve a defined continuous segment of the motion picture.
  • Fig. 1 is a somewhat diagrammatic view as seen from above illustrating a conventional rolling loop motion picture projector
  • Fig. 2 is a view generally in the same direction as Fig. 1 but showing only the film path and associated elements of a rolling loop projector in accordance with the present invention
  • Fig. 3 comprises views denoted 3(a) and 3(b) illustrating operation of the projector at 48 and 24 fps respectively;
  • Fig. 4 is an enlarged detail view of part of
  • Fig. 2 showing a film sensor
  • Fig. 4(a) is a detail view of part of the film shown in Fig. 4; and.
  • Figs. 5(a) and 5(b) illustrate segments of two film strips showing representative frames as shot, for example, at 48 and 24 fps respectively. DESCRIPTION OF PREFFJMrar. T g UQnTMRWT
  • the principal components of a conventional rolling loop film projector comprise a rotor 20 and a stator 22 that together define a gap 24 forming a film passage.
  • Film 26 travels from a supply reel 28 to a take-up reel 30.
  • Film is fed into the gap 24 at a controlled rate by an input sprocket 32 and is withdrawn from the film gap by an output sprocket 34.
  • An aperture block 36 is provided between the two sprockets and has associated therewith a projection lens assembly 38 and, within the rotor, a projection lamphouse 40.
  • a cam unit 42 for decelerating the film as it approaches film registration pins, (not shown) at the position of the aperture block.
  • the input sprocket 32 feeds film into successive gaps in the rotor, forming film loops which progressively develop as the film approaches the aperture block 36 and then decay towards the sprocket 34.
  • successive frames of film are laid onto a lens element (not shown) and the film is registered with the registration pins for projection.
  • Fig. 3 shows part of the rotor 20. Gaps in the rotor are indicated at 44 and shutters extending across those gaps are denoted 46. In Fig. 3(a), loops 26 of film are shown in each of the rotor gaps 44 while in Fig. 3(b) loops are shown in every alternate gap only.
  • the rotor may be provided with 16 gaps each with its own individual shutter 46. If loops are allowed to form in each gap as shown in Fig. 3(a) a frame rate of 48 fps is achieved if the rotor rotates at 180 rpm. At the same rotor speed, if loops are allowed to form in every alternate gap only, the frame rate will be 24 fps.
  • Fig. 2 illustrates one way in which it is possible to selectively control the film so as to achieve loop formation in every gap or only in every alternate gap.
  • like reference numerals have been used to denote parts that correspond with parts shown in the other views.
  • the film travels from a supply reel 28 to a take-up reel 30 via an input sprocket 32 and an output sprocket 34.
  • a diagrammatic representation of a lens assembly 38 indicates the position of the aperture block
  • a cam unit 42 is provided adjacent the aperture block.
  • individual electric servo motors 48, 50 and 52 are provided for driving, respectively, the input sprocket 32, the cam unit 42 and the output sprocket 34. Similar servo motors 54 and 56 are also provided for controlling the supply reel 28 and the take-up reel 30. A controller for the servo motors 48, 50, 52, 54 and 56 is shown at 57.
  • Film “accumulators” generally indicated at 58 and 60 are provided respectively downstream of the supply reel 28 and upstream of the take-up reel 30. While constructional details have not been shown, each accumulator may comprise a set of three idler rolls 58a, 58b and 58c and 60a, 60b and 60c, arranged in a triangular configuration as shown in Fig. 2.
  • the centre •roll is displaceable as indicated by the arrows 62 and 64 respectively to accommodate variations in the amount of film in the respective "runs" between the two reels and the rotor/stator combination. Suitable biassing means are provided for the centre roll to maintain appropriate tension in the film.
  • a film sensor assembly 66 is provided immediately downstream of the supply reel 28 and is shown in detail in Fig. 4.
  • the sensor assembly comprises a light source 68 and a photocell 70 positioned so that the light source 68 normally shines through the film onto the photocell except when interrupted by so-called "witness" marks appropriately positioned on the film.
  • One of those marks is shown at 72 in the form of an opaque square that will interrupt the light beam.
  • the input sprocket 32 is the primary element that controls the frame rate at which the projector operates. The normal operating rate will be, say, 48 fps.
  • Controller 57 is programmed to cause the servo motor 48 to drive input sprocket 32 at a constant rotational speed such that loops will form in each of the rotor gaps 44 as shown in Fig. 3(a) .
  • the other servo motors will be driven at correspondingly related speeds.
  • controller 57 will cause the input sprocket 32 to rotate intermittently at a frequency and rate selected to feed film into alternate ones only of the rotor gaps 24 as shown in Fig. 3(b) .
  • the film frame rate will then be half the rate achieved with the arrangement illustrated in Fig. 3(a). It may in fact be possible to control input sprocket 32 sufficiently precisely,that the input sprocket can also be used as a film deceleration means, in which case cam unit 42 may be omitted.
  • witness marks are provided on the film between portions of the film that were shot at different frame rates. These marks are sensed by sensor 66 which then signals the controller 57 to appropriately change the speeds of the various servo motors and change servo motor 48 from continuous to intermittent operation or vice versa.
  • Sensor 66 is located a finite distance in advance of the input sprocket 32. Since the film will be travelling at a constant speed immediately before each change in frame rate, controller 57 is programmed to change the frame rate at exactly the appropriate time; that is, as soon as the frames that were shot at the different rate begin to enter the gap between the rotor and the stator. This time lag is necessary in order to accommodate the inertia in the supply reel 28 and take-up reel 30; controller 57 is programmed to begin changing the speeds of those reels sufficiently before the speed of the input sprocket changes to allow for this inertia.
  • Figs. 5(a) and (b) illustrate respectively sections of film that were shot at 48 fps and 24 fps
  • Fig. 5(a) and (b) illustrate respectively sections of film that were shot at 48 fps and 24 fps
  • three frames are .shown representing a subject (a car) 76 travelling from left to right across the field of view (the film moving from right to left) .
  • the subject has moved from a position in which it appears to be entering the frame from the left-hand side to a position in which it has almost reached the right-hand side of. the frame.
  • Fig. 5(a) three frames are .shown representing a subject (a car) 76 travelling from left to right across the field of view (the film moving from right to left) .
  • the subject has moved from a position in which it appears to be entering the frame from the left-hand side to a position in which it has almost reached the right-hand side of. the frame.
  • Figs. 5(a) and (b) also illustrate the steps in the method of the invention of selecting two different film frame rates for recording different scenes, predetermining for each scene one of the selected film rates and recording each scene on film at the film frame rate that was predetermined for that scene.
  • the 48 fps frame rate of Fig. 5(a) would be selected for fast action scenes while the 24 fps frame rate of Fig. 5(b) would be selected for slower scenes.
  • Witness marks (as marks 72) would be placed on the final film print between the segments that were shot at different frame rates and those witness marks would then be used to control the projector in which the film is shown, as described previously in connection with Fig. 2.
  • a rolling loop projector methods other than those disclosed herein may be used for forming film loops or withholding film to prevent loop formation.
  • the rotor of a rolling loop projector preferably rotates at constant speed and the frame rate is varied by feeding film into all or selected ones only of the gaps, different frame rates could be achieved by varying the rotor speed (and correspondingly varying the film input speed) .
  • other frequencies could be used. For example, loops could be injected into every third gap only if a one to three frame rate change was required.
  • the rotor need not have an even number of gaps.
  • a high frame rate of 36 frames per second could be achieved by feeding film into every second gap in the rotor and a lower frame rate of 24 frames per second could be achieved by feeding film into every third gap. Film need not be fed into the same gaps on successive revolutions of the rotor .
  • the film may be fed intermittently through the projector using film feeding means that can be changed instantaneously (say within one frame period) between one intermittent film feeding rate and another such rate.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Projection Apparatus (AREA)

Abstract

On tourne un film comprenant une multiplicité de séquences en choisissant au moins deux cadences d'images différentes lors du tournage des séquences, en prédéterminant l'une des cadences pour chaque séquence, et en enregistrant chaque séquence sur film à la cadence d'images prédéterminée pour cette séquence. Le film est par la suite présenté en étant projeté à l'aide d'au moins un projecteur susceptible de fonctionner selon au moins deux cadences de projection différentes. La projection est contrôlée de façon que le film soit projeté en continu alors que la cadence de projection est modifiée, afin que chaque séquence soit projetée à une cadence d'images correspondant à celle à laquelle elle a été filmée. Le projecteur peut être du type à boucle tournante, comprenant un rotor pourvu d'un nombre d'espaces pair dans lesquels des boucles de film sont produites, la modification de la cadence d'images étant effectuée lorsque le film est alimenté dans tous les espaces ou uniquement dans des espaces alternés, à une vitesse de rotor constante.
PCT/CA1992/000397 1991-09-23 1992-09-14 Procede et appareil destines a la realisation et a la projection d'un film WO1993006520A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US76427091A 1991-09-23 1991-09-23
US764,270 1991-09-23

Publications (1)

Publication Number Publication Date
WO1993006520A1 true WO1993006520A1 (fr) 1993-04-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA1992/000397 WO1993006520A1 (fr) 1991-09-23 1992-09-14 Procede et appareil destines a la realisation et a la projection d'un film

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AU (1) AU2563492A (fr)
WO (1) WO1993006520A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5627614A (en) * 1995-08-25 1997-05-06 Weisgerber; Robert C. Method for imparting both high-impact cinematic images and conventional cinematic images on the same strip of motion picture film
WO1998008140A1 (fr) * 1996-08-23 1998-02-26 Weisgerber Robert C Procede servant a imprimer sur la meme bande d'un film cinematographique des images animees produisant une forte impression et des images animees classiques
EP1738221A4 (fr) * 2004-04-20 2009-10-28 Imax Corp Procedes de transport d'un film a commande electronique et systemes

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914036A (en) * 1973-06-30 1975-10-21 Nippon Kogaku Kk Film frame feed device in a compact motion picture projector
DE2057375B2 (de) * 1969-11-24 1979-11-15 Multiscreen Corp. Ltd., Galt, Ontario (Kanada) Filmtransporteinrichtung, insbesondere für einen Filmprojektor
EP0416940A2 (fr) * 1989-09-08 1991-03-13 Imax Corporation Projecteur de film 3-D
EP0416941A2 (fr) * 1989-09-08 1991-03-13 Imax Corporation Projecteur de film 3-D
US5106185A (en) * 1988-03-11 1992-04-21 Arnold & Richter Cine Technik Gmbh & Co. Control and regulating device for film transport in a film projector

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2057375B2 (de) * 1969-11-24 1979-11-15 Multiscreen Corp. Ltd., Galt, Ontario (Kanada) Filmtransporteinrichtung, insbesondere für einen Filmprojektor
DE2066143B2 (de) * 1969-11-24 1980-12-11 Multiscreen Corp. Ltd., Galt, Ontario (Kanada) Einrichtung zur Stoßdämpfung bei der Ausbildung einer Filmschleife in einer Filmtransporteinrichtung
US3914036A (en) * 1973-06-30 1975-10-21 Nippon Kogaku Kk Film frame feed device in a compact motion picture projector
US5106185A (en) * 1988-03-11 1992-04-21 Arnold & Richter Cine Technik Gmbh & Co. Control and regulating device for film transport in a film projector
EP0416940A2 (fr) * 1989-09-08 1991-03-13 Imax Corporation Projecteur de film 3-D
EP0416941A2 (fr) * 1989-09-08 1991-03-13 Imax Corporation Projecteur de film 3-D

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5627614A (en) * 1995-08-25 1997-05-06 Weisgerber; Robert C. Method for imparting both high-impact cinematic images and conventional cinematic images on the same strip of motion picture film
WO1998008140A1 (fr) * 1996-08-23 1998-02-26 Weisgerber Robert C Procede servant a imprimer sur la meme bande d'un film cinematographique des images animees produisant une forte impression et des images animees classiques
EP1738221A4 (fr) * 2004-04-20 2009-10-28 Imax Corp Procedes de transport d'un film a commande electronique et systemes
US8147065B2 (en) 2004-04-20 2012-04-03 Imax Corporation Electronically controlled film transport methods and systems

Also Published As

Publication number Publication date
AU2563492A (en) 1993-04-27

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