US3795440A - Multi-track sound system for narrow-width motion picture film - Google Patents

Abstract

Narrow-width motion picture systems are provided with a multiple-track sound capability by providing the film with a plurality of magnetic recording stripes and by providing projecting equipment with specially devised adapters for playing back sound tracks recorded on these stripes. The adapters are designed to be compatible with existing equipment, and they include a switching arrangement for permitting the sound tracks to be replayed separately or in combination.

Description

United States Patent 1191 Swerdlow et al.

MULTl-TRACK SOUND SYSTEM FOR NARROW-WIDTH MOTION PICTURE FILM Inventors: Robert Swerdlow, Toronto, Ontario; Emil Schilder, Kensington, Ontario, both of Canada Assignee: Cinacor, Ltd., Ontario, Canada Filed: Mar. 31, 1971 Appl. No.: 129,935

US. Cl. 352/27, 179/1002 MP Int. Cl. G03!) 31/02 Field of Search 352/26, 27, 28, 29, 30, 37; 179/1002 MP References Cited UNITED STATES PATENTS 4/1931 Kuchenmeister 352/37 UX 12/1934 Hanna 352/30 X 8/1949 Rossmann et al... 352/37 2/1952 Camras [79/1002 2/1953 Blaney 352/27 X Mar. 5, 1 974 2,676,023 4/1954' lSOm 352 27 ux 2,695,545 ll/l954 Evans 2,826,] 12 3/1958 Mueller 3,017,466 1 1962 Kerr 3,452,16l 6/1969 I- I afler 3,537,781 1 1970 Lemelson 352 27 x Primary Examiner--Joseph F. Peters, Jr. Assistant Examiner-Michael L. Gellner Attorney, Agent, or Firm-Pennie & Edmonds [57] ABSTRACT Narrow-width motion picture systems are provided with a multiple-track sound capability by providing the film with a plurality of magnetic recording stripes and by providing projecting equipment with specially devised adapters for playing back sound tracks re corded on these stripes. The adapters are designed to be compatible with existing equipment, and they include a switching arrangement for permitting the sound tracks to be replayed separately or in combination.

3 Claims, 8 Drawing Figures PATENTEUNAR 51w 3.795.440

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ATTORNEYS INVENTORS ROBERT SWERDLOW EMIL SCHILDER PATENTED 5 sum 3 or 4 I N VEN TORS ROBERT SWERDLOW EMIL SCHI LDER B MM ATTORNEYS PATENTED 5 74 SHEET '8 BF 4 FIG; 6

Pickhp Heads Ourpur SWS 1 med 5 PSA r 6 .M G U G E Photocell To Microphone a Amplifiers INVENTORS ROBERT SWERDLOW EMIL SCHILDER flw W W 5% ATTORNEYS MULTI-TRACK SOUND SYSTEM FOR NARROW-WIDTH MOTION PICTURE FILM I BACKGROUND OF THE INVENTION The present invention relates to a multiple-track sound recording and reproducing system for use with narrow-width motion picture film.

Users of narrow-width motion picture equipment have long desired a multiple-track sound capability. The'provision of such a capability would produce substantial advantages to the educational institutions, semi-professionals and amateurs who generally use such equipment. For example, educational institutions (which are generally limited to 8 mm or 16 mm equipment by economic necessity), have long sought motion picture films which have different sound tracks for student audiences of different grade levels. In addition-- particularly in urban areas-they have sought films having different sound tracks in different languages for their students who are not yet proficient in English. Moreover, semi-professional and amateur moviemakers have long been desirous of obtaining a multitrack capability so that they can 'use one track for dialogue while making movies and additional tracks for subsequently adding background music or even sound effects.

In addition, the provision of a multiple-track sound capability can significantly reduce the amount of film required. One multi-track film can replace several single-track films, reducing the film cost and the cost of storage in film libraries.

While multi-track systems are available to professionals, they have not been generally available to amateurs and semi-professionals. For example, U. S. Pat. No. 2,628,288 issued to D. L. Blaney on Feb. 10, 1953, discloses a two-track system using one optical recording track and one magnetic track. This system is useful for the professional but of only limited value to the amateur who generally does not have the complex equipment required for optical recording. See U. S. Pat. No. 2,479,868, issued to P. F. Rossman et al., Aug. 23, 1949.)

Films having two magnetic stripes are commercially available, but it has not been considered possible to record an independent sound track on the second stripe. Instead, the stripe has b e e n rnerely used for balance. (See SMPTE Standard PH 22, 101-4963.) In U. S. Pat. No. 2,452,16l'issued to D. I-Iaffler on June 24, 1969, it was suggested that the second stripe'could be used in conjunction with the first stripe to record a stereophonic track; but even in this patent the supposed incapacity of the second stripe to record an-independent track was noted; and it was used only to record the difference signal of the stereophonic track.

SUMMARY OF THE INVENTION Contrary to prior expectations, it has been found that narrow-width motion picture film can include a plurality of magnetic recording stripes, each capable of recording an independent sound track. In accordance with the invention, narrow-width motion picture systems are provided with a multiple-track sound capability by providing the film with a plurality of magnetic recording stripes and by providing projecting equipment with specially devised adapters for playing back these tracks. The adapters are designed to be compatible with existing equipment. The sound tracks can be replayed separately or simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages, the nature of the present invention, and its various features will appear more fully upon consideration of the various illustrative embodiments now to be described in detail in connection with the accompanying drawings.

In the drawings:

FIGS. 1A and 1B illustrate multi-track narrow-width motion picture film in accordance with one aspect of the invention;

FIG. 2 illustrates the sound station of a typical prior art motion picture projector;

FIG. 3 illustrates an adapter for a typical motion picture projector to permit the playback of multi-track, narrow-width film;

FIG. 4 illustrates a first alternative embodiment of such an adapter;

FIG. 5 illustrates a second alternative embodiment;

FIG. 6 is a circuit diagram of a system for controlling the operation of the playback systems shown in FIGS. 3-5; and

FIG. 7 illustrates a recording head for recording sound tracks onthe film of FIGS. 1A and 18.

For convenience of reference, the same numbers are used to denote corresponding elements throughout the drawings. 1

DETAILED DESCRIPTION Referring to the drawings, FIGS. IA and 1B show front and cross-sectional views, respectively, of a multitrack, narrow-width motion picture film in accordance with one aspect of the invention. The film shown in FIG. IA comprises a strip of conventional, narrowwidth motion picture film 10 such as 16mm or super- '8mm film including sprocket holes 11, an optical track 12, and a plurality of magnetic tracks 13, each capable of recording an independent sound track. As can be' seen by reference to FIG. llB, three tracks are shown in this illustrative embodiment (the stripe adjacent optical track 12 comprising two separate tracks). It is clear, however, that up to six tracks can be provided by putting three additional tracks on the underside of the film. Preferably, a double magnetic track is placed on or adjacent the conventional optical track in the manner disclosed in the above-mentioned patent to Blaney. The remaining track is disposed on the opposing edge of the film.

The magnetic tracks comprise stripes of pulverized magnetic material such as iron oxide powder deposited or coated on the film in accordance with techniques well known in the art. Each track is approximately onesixteenth inch wide. Stripes of this width are sufficient to record an independent sound track, and they can be predisposed on the edges of film away, from the exposed or exposable portion.

The film in a conventional projector for sound movies is fed from a reel past the visual projecting system with an intermittent movement, and thereafter it passes to a sound station where it travels with a uniform movement, the sound being normally picked up from an optical sound track along one edge of the film.

FIG. 2 illustrates a typical conventional mechanism for obtaining uniform movement of the film, subsequent to its visual projection. The mechanism consists rected through the correct path to emerge of a bottom loop sprocket 20, which is driven,"and over which the film 21 passes to a sound drum 22 having a flywheel (not shown), the film being pressed down wardly by a spring loaded snubber idler 23. The film has an optical sound track adjacent one edge, and light from an exciter lamp 24 is directed through a lens 25 onto the optical track to cause sound reproduction in the conventional way. .The sounds being reproduced bottom loop sprocket and out of the projector to a takeup reel (not shown)- The projector is often pro-' vided with guide plates 28 which make it possible to insert a film by simply pushing its leading edge into the projector, the guide plates ensuring that the film is ditakeup reel.

In accordance with a second aspect of the invention,

at the an especially designed adapter is provided for permitting the playback of the additional magnetic tracks. In particular, the adapter is designed to be interposed between the conventional sound drum and the takeup reel so that it can be added to most conventional projectors.

FIG. 3 illustrates such an adapter comprising, in essence, a magnetic pickup, an auxiliary sound drum and a suitable arrangement of idlers. More specifically, the adapter comprises a spring loaded idler 30 for receiving film from the conventional sound drum, and a magnetic pickup 31 including a plurality of separate pickup heads. These heads should be constructed of a material which is sufficiently durable to withstand contact with motion picture film (which is substantially harder than conventional magnetic tape). The material should not be so soft that the film will wear it down, and it should not be so hard that it will cut through the film.

A second idler 32 and a subsequent sound drum 33 are positioned to press the film against the heads of pickup 31 with each sound track in contact with a different head. I

A third idler 34 is positioned for receiving film from the sound drum and feeding it to the snubber idler of the conventional sound station at the same angle it would have come directly from the conventional sound drum.

In operation, after the film leaves the conventional sound drum 22, it passes downwardly (following the unbroken arrows) past spring loaded idler 30 (which keeps it in tension), around idler 32 and over magnetic pickup 31. For a film having three magnetic sound tracks, the pickup has three heads. The idler 32 and subsequent sound drum 33 press the film against these heads, with each sound track in contact with a different invention in which the magnetic pickup is disposed between the sound drum of the conventional sound station and an adapter sound drum. Specifically, this adapter comprises a magnetic pickup 31 and a sound drum 33 positioned with respect to the sound drum of the conventional sound station to press the film against the pickup. An additional idler 40, which is optional, may be provided between sound drum 33 and the conventional snubber idler in order to provide additional protection against snaking of the film. However, this additional idler is unnecessary if drum 33 is disposed to feed film to the snubber idler at approximately the same angle as it would arrive from the sound drum of the conventional sound station. I V

The components of the adapter can all be mounted on a single casting (not shown) that can be inserted as a unit into the conventional projector. The adapter can be provided with guide plates 41 to ensure that a film can be inserted by pushing its leading edge through the projector and the guide plates to guide it through the adapter. Additional means (not shown) can be provided to shift one or more guide plates to cause the film as it is inserted to bypass the adapter and follow the conventional path when the adapter is not required. This feature preventsiunnecessary wear on the magnetic pickup heads when they are not in use.

As indicated by the broken outline in FIG. 4, the

magnetic pickup can be located at the opposite side of the film if magnetic tracks are provided on thebase side of the film. Or, if desired, both sides of the film can be provided with up to three magnetic tracks, and the adapter can be provided with a magnetic pickup for each track, thus providing for a total of six magnetic tracks. 7

As previously mentioned, the conventional optical sound pickup occurs at a frame which is 26 frames ahead of the frame being visually projected. Similarly, the magnetic pickup heads and the sound recording on the magnetic tracks of the film must bear a known relationship to the pictures on the film, and a convenient standard is that the magnetic pickup occurs 32 frames ahead of the frame being visually projected.

FIG. 5 shows an additional and preferred embodiment of the invention in which the magnetic pickup is fixedly disposed adjacent an auxiliary drum. The drum is located in the film path between the sound drum of the conventional sound station and the subsequent snubber idler. The advantage of this embodiment'is that it provides the desired adaptation with a minimum of new components.

In particular, this adapter comprises a magnetic pickup "31 including a plurality of separate pickup heads fixedly disposed-adjacent an auxiliary'rotatable drum 42 by one or more mounting clamps 43 engaging a mounting tube 44. The heads of the magnetic pickup are conveniently disposed on either side of drum 42 to magnetically engage magnetic tracks on both edges of film passing around the drum. The drum, in turn, is positioned to feed film passing therearound to the conventional snubber idler 26 at any angle suitable for subsequent feeding into conventional idler 27.

As is the case for the other embodiments, this adapter can be mounted on a single casting that can be inserted as a unit into a conventional projector. Suitable guide plates 45 are provided, and guide plate shift- I ventional sound system including an optical pickup,

such as a photocell 50, a pre-amplifier A and an amplifier A In addition, a plurality of magnetic pickup heads 51-53 are connected by leads 54-56, respectively, and a switch arm S to amplifiers A and A The output of amplifier A in turn, is connected to amplifier A in the conventional sound system of the projector through switch S An equalizer 57 is provided in parallel with A and a pre-set screw adjustment 58 is disposed between A and A to equalize the volumes between the optical and magnetic tracks. With this arrangement, one can use a magnetic track, the optical track, or a desired combination of any of these tracks.

FIG. 7 is a schematic illustration of a recording head useful in recording sound tracks on the multi-track film of FIGS. 1A and 1B. The head differs from conventional recording heads primarily in that it includes a plurality of magnetic recording coils 60, 61, and 62 positioned to record on each of the magnetic tracks 13 of film 10. The coils 60, 61, and 62 are independently controllable and are preferably connected by separate leads 63, 64, and 65, respectively, to a track selecting switch 66. The switch, in turn, can be connected to a suitable input microphone and amplifier arrangement.

While the invention has been described in connection with specific embodiments, it is understood that these embodiments are merely illustrative of the many possible specific embodiments which can represent applications of the principles of the invention. Numerous and varied other arrangements can be devised in accordance with the principles of the invention without departing from the spirit and scope of the invention.

We claim:

1. A sound reproduction system for a narrow-width motion picture system comprising:

narrow-width picture film including a plurality of magnetic tracks each capable of recording an independent sound track;

a motion picture film projector capable of sound projection for receiving said narrow-width film, said projector including a sound reproduction system of the type including a driven loop sprocket, a sound drum and idler means for pressing film onto said sound drum as it passes from said sprocket around said sound drum and back towards said sprocket; and

an adapter for said projector for permitting the playback of sound tracks recorded on said magnetic tracks, said adapter comprising a magnetic pick-up including a plurality of separate pickup heads disposed in a position adjacent the return film path between said sound drum and said loop-sprocket, first idler means for tensioning said film-spring means for spring biasing said idler, second idler means for guiding said film, drum means for maintaining said film in alignment with said magnetic pickup head, said second idler means and said drum means cooperating together to press said film against said magnetic pickup head, a third idler means for directing said film back along the path defined by said sound drum and switching means for switching the sound system of said projector among the separate pickup heads of said magnetic pickup. 2. A system according to claim 1 wherein said narrow-width motion picture film includes an optical sound track.

3. A system according to claim 1 wherein said plurality of magnetic tracks comprises at least three magnetic tracks.

Claims (3)

1. A sound reproduction system for a narrow-width motion picture system comprising: narrow-width picture film including a plurality of magnetic tracks each capable of recording an independent sound track; a motion picture film projector capable of sound projection for receiving said narrow-width film, said projector including a sound reproduction system of the type including a driven loop sprocket, a sound drum and idler means for pressing film onto said sound drum as it passes from said sprocket around said sound drum and back towards said sprocket; and an adapter for said projector for permitting the playback of sound tracks recorded on said magnetic tracks, said adapter comprising a magnetic pick-up including a plurality of separate pickup heads disposed in a position adjacent the return film path between said sound drum and said loop sprocket, first idler means for tensioning said film, spring means for spring biasing said idler, second idler means for guiding said film, drum means for maintaining said film in alignment with said magnetic pickup head, said second idler means and said drum means cooperating together to press said film against said magnetic pickup head, a third idler means for directing said film back along the path defined by said sound drum and switching means for switching the sound system of said projector among the separate pickup heads of said magnetic pickup.

2. A system according to claim 1 wherein said narrow-width motion picture film includes an optical sound track.

3. A system according to claim 1 wherein said plurality of magnetic tracks comprises at least three magnetic tracks.

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