US2074406A - Method and apparatus for recording and reproducing sound - Google Patents

Description

March 23, 1937. P. I oHN ET A1. '2,074,406

METHOD'AND APPARATUS FR RECORDING AND REPRODUGING SOUND Filed July 26, 1953 2 Sheets-Sheet 1 fnnnnn'mnnnnn'nmmnnnml DUUUUUUEUUUU my. 3. f6 M @y 0' I l' 47 D .'/5 A INVENTORS @LFO/V60 CORTELLH' ATTO RM March\23,n 1937. P. LOHN ET AL METHOD AND APPARATUS FO'R RE CORDING AND REPRODUCING SOUND 2 Sheets-Sheet 2 Filed July 26, 1935 M E sf www m62 E L wo? r an. .Wr MP 7 an I ATTOR E S Patented Mal. 23, 1937` f f A 2,074,406

Peter New York, N. Y., and Alfonso CortellaiLeonia, N. J.

Application July 26, 1933, Serial No. 682,292

2 Claims.

'I'his invention relates to improvements in the recording and reproduction of sound and has particular reference to a method and apparatus for making and reproducing a sound record on a recording medium such, for example, as a lm employed in the motion picture art. vThe invention pertains more especially to the production of a motion picture iilm which is capable of being employed in conjunction with 1o projectors of the type used in the home and which will enable the synchronous reproduction Vof sound with the picture on the film, but it will be understood that the inventive concept embodied herein is not to be construed as limited l5 to such use.

Various kinds of lms having sound records thereon have heretofore been used amongvwhich are those in which the film is provided with a photographic sound record. Such a film has been ioundquite effective in projectors employed in motion picture theatres. But the necessity of utilizing the expensive equipment, including photo-electric cells and associated apparatus, makes its use with a home projector too expensive and therefore impractical either when such equipment is installed originally in the machine or is provided as a separate unit for application to a projector theretofore' unequipped for the reproduction of sound. A,

Another previous proposal involves the formation of an ordinary hill and dale record groove cut in a surface of the lm. Such a record necessitates the use of a stylus which, if of a relativelysoft material, Wears downand must be frequently replaced, and which, if of a hard substance such as steel or the ,likefhasvan adverse effect upon the record groove. In either instance, the reproduction of the sound is materially impaired and its quality therefore diminished.

A further prior suggestion, which has been practiced to some extent, resulted in forming the record groove in an edge ofthe film for engagement :by the stylus of a pick-.up device. Such.

practice has never, so far as known, been entirely successful in obtaining quiet reproduction, owing to the roughness of the edge of the lm as compared to the surfaces thereof, which roughness, in spite of attempts to obliterate'the same by polishing said edge, has resulted in the production of extraneous sounds. `Nor has such reproduction .approached perfection in its accuracy' due to the .tendency of-the lm to buckle by reason of the pressure of the stylus thereagainst. In accordance with the present invention, it

is proposed to eliminate the diiliculties encountered in known types of sound recording films by the production of an improved recording medium in which the sound record therein is ofl such nature that its engagement with a recording stylus will result in an accurate reproduction,

without extraneous noises, of the sound to bereproduced. The present medium is also of such a character that the same can be produced at a cost which will make feasible its use with home projection apparatus.

The invention furthercontemplates a sound record produced in a exible strip, as for example a photographic lm, by a relative vibratory movement between said iilm and a cutting tool which will result in the latter cuttinga record groove in one surface and an edge of said strip. The term trace as employed throughout this description is intended, in its broadest sense, to cover a recordin which either a continuous cut or a series of individual but correlated cuts combine to produce the desired sound waves.

A still further feature of the invention resides in reproducing the sound record in a flexible strip by moving the latter past a pick-up device in such a manner that the inherent tendency of the strip to assume a normal flat position is utilized to effect sufficient pressure ofthe strip and its record against the stylus of said device to faithfully reproduce the sound.

The inventive idea involved is, capable of receiving a variety of expressions, some of which,

`for purposes of illustration, are shown in the accompanying drawings, wherein:

Figure 1 is an enlarged fragmentary plan view l of a motion picture lm to which the sound record of the present invention has been applied.

Figure 2 is a 4greatly enlarged transverse section through the lm, the dotted lines indicating thev relative position of the stylus of a pick-up device when engaged with the sound record.

Figure 3 is a diagrammatic elevation of one form of apparatus used for recording sound upon the lm.

. Figure 4 isan enlarged elevation, partly in section, of the sound record-forming apparatus of Figure 3.

Figure 5 is a view similar to Figure 4 showing another form of recording apparatus.

Figure 6 is an assembly view, in elevation, of a projection apparatus, and sound reproducing mechanism made in accordance with a present invention.

Figure '7 is an enlarged longitudinal section through a. part of the reproducing mechanism.

Figure 8 is a plan view of the mechanism shown in Figure 7, With the casing thereof in section, and

Figure 9 is an enlarged transverse section substantially on the line 9-9 of Figure 8.

The present invention is illustrated in its application to a photographic lm such as used in motion picture projecting machines but it is to be expressly understood that the sound record involved herein may be applied to any other kind of flexible recording medium withoutdeparting from the spirit or scope of the invention. The lm IIJ shown herein is of the usual type made of plasticized material including the united layers of celluloid II and sensitized emulsion l2 the former of which is of the greater thickness. According to the present invention the record trace generally indicated by the numeral I3 is preferably formed, by a cutting means later to be described, in the celluloid surface II and a longitudinal edge of the lm. The trace consists of minute series of cuts made in said surface and edge and these cuts extend transversely of the film body, and preferably diagonally thereof asclearly shown in Figure 1, although it is conceivable that they may be perpendicular to said edge. The cuts forming the record trace vary in depth and length in accordance with the frequency of the vibrations which are transmitted either to the lrn or to the cutting tool, as will' appear in the course'ot the description, but it is desirable, in order to effect reproduction of high quality, that the depth of said cuts at no point shall be equal to the thickness of the film and preferably do not exceed the thickness of the celluloid layer II. Also, due to the relative position of the edge of the film and the cutting tool, the length of the cut in the film surface will be substantially the same as the greatest depth of the film, as shown in Figure 2. In no event, however, will the length of the cut be such that it will extend into the central area of the film which is occupied by the picture photographed upon the emulsion side I2. When the cuts of the trace are formed diagonally, as shown in Figure 1, they preferably extend outwardly in a direction opposite that to the travel of the film as it is being moved past and engaged with the stylus of a pick-up deviceso that said stylus, which may be of any desiredA hard material and of substantially the form shown in Figure 2, will easily and accurately .engage the undulations of the record trace with a constancy which will faithfully reproduce the record. In Figure 1 several blank spaces have been shown between series of the cuts forming .the record trace. These blank spaces are actually a part of the complete sound record but represent silent intervals in said record.` By reason of the -fact that the sound record is formed in the ysmooth celluloidsurface of the film the engagement of the stylus with the saidblank spaces will reduce to an absolute minimum any possibility of scratching noises being createdlduring the said silent intervals.

In Figures 3 and 4 there is illustrated diagrammatically one Vform of recording apparatus.

The film IU, with its celluloid side I I uppermost is fed lbetween rollers I4 to and through the armature I5 of a quick-acting electromagnetic device I6 of any well-known construction capable of responding to high frequencies and accurately transmitting the same to its armature in order to vibrate the latter in accordance with such frequencies, there being a spring I5' connected to the armature to hold the' latter in engagement home projection apparatus.

with the cutting tool I'I against the action of the device I6. The cutting tool is preferably in the form of a disc knife, driven at the desired speed by a flexible shaft I8, and is suitably suspended adjacent the edge of the lm in which the sound record is to be made and the plane of said knife is preferably disposed diagonally to the direction of travel of the film so that the cuts forming the record trace will be disposed diagonally relative to the longitudinal edge of said film. Preferably, when the electromagnet I6 is deenergized the armature I5 is so positioned that the film is in contact with the cutting edge of the cutter I1 but as the armature is vibrated said film, as it is moved along, will be likewise vibrated relative to the cutter and the desired cuts made in the surface II and its longitudinal edge.

I y The apparatus shown in Figure 3 is employed when translating or transferring a sound record from one lm to another and is especially adapted for making the sound record in asmall lm, such as the film II) which may be used.with small The master film I9 which is employed to form the sound record in the film I0 has a photographic sound record therein and is fed by series of rollers 20 between a projection unit and a photo-electric cell conventionally illustrated by the numerals 2l and 22, respectively. The cell 22 is responsive to the sound record on the lm I9 and impulses are transmitted from said cell through the circuit 23 connected to the electromagnet I6, there being a suitable amplifying unit 2t interposed in said circuit between said magnet and the photo-electric cell.

Instead of vibrating the film I0 into contact with the cutter I'I, as shown in Figures 3 and 4, the film I0 as illustrated in Figure 5, may be moved through a stationary guide 25 and the cutter 26, constantly rotated by the flexible shaft 2l, may be carried by the solenoid of the electromagnetic device 29 which would be included-in the circuit 23 in the same manner as the device I6. Thus the cutter 26 would be vibrated in response to the impulses transmitted thereto by the photo-electric cell and said cutter would constantly be moved into and out of engagement with the surface I l of the lm and its edge to form the record trace therein.

Figures 6 to 9 of the drawings illustrate an apparatus for reproducing the sound record of the abov'e described film. In Figure 6 there is conventionally shown various instrumentalities which may be employed in a combined sound and motion picture apparatus especially suitable for home use. The numeral 30 indicates a picture projection machine which may be of a well known construction. The sound reproducing unit generally indicated by the numeral 3l is designed so that it can be sold as a separate unit and coupled with a projection machine already in use and has associated therewith any well known loud speaker 32 electrically connected to a pick-up device 33 located within the casing of the unit 3|. The film I0 having the record groove I3 therein is mounted upon a reel 34 supported upon the exterior of the casing 3| and is fed from said reel around an idler 35 and from thence into said casing with the celluloid side of the iilm' containing the record groove uppermost. As the lm enters the casing 3| it is passed through what is commonly known as a gate consisting of the horizontally spaced guide members 36 which, in this instance, are made arcuate in cross section as best shown in Figure 9. The purpose of this gate is to tension the portion of the lm located between the members of the gate and where the sound record |3 thereof is being engaged by the stylus of the pick-up device. In accordance with 5 the present invention it is proposed to utilize the natural tendency of the film to assume a flat condition after it has been flexed in order to obtain the pressure sufficient to cause the record in the film to properly engage the stylus of the pick-up 10 device. To this end, there is provided an idler roller "31 journalled on the shaft 38 extending between'the side walls of the casing 3| beneath the lm I and in vertical alignment with the device 33.v The bearing surface of the roller 31 engages 15 the lower or emulsion side of the film I0 and is curved transversely so that the lm l0 will be After leaving the `tension gate in its travel through the reproducing unit the lm is passed over the drive sprocket 39 and from thence successively under and over the idlers 4l), 4| and 30 42, the latter being located on the exterior of the casing 3|. From this point the film is led to the projection machinev 30 and between the latter and said idler 42, said film is twisted, as indicated at 43, so as to bring the emulsion side 'thereofl 35 uppermost.

In order to secure absolute synchronism between the projection machine 30 and the sound reproduction, the shaft of said machine is connected by a flexible shafting 44 to a shaft 45` extending transversely of and mounted in the casing 3|, said shaft carrying the drive sprocket 39.l A'pinion 46 on said shaft 45 meshes with a bevel gear 4-'l carried by the drive shaft 48 operated by any suitable prime mover such as an electric motor (not shown) What is claimed is:

1. Sound reproducing apparatus, comprising, in combination, a pick-up device, a film having a sound record in one surface thereof, means to move said lm and said device relative to each other with the stylus of the latter in engagewith said sound record, and means to bow said film transversely so that the surface thereof containing the sound record will be in the convex arc of curvature of the lm.

2. Sound reproducing apparatus, comprising, in combination, a pick-up device, a lm having a vsound record in one edge of one surface thereof,

means to move said lm and said device relative to each other with the stylus of the latter in engagement with theedge of said film containing said soundrecord, an arcuate guide through which said lm is moved, and a roller having a transversely curved surface, contacting only the medial portion of the surface of said film opposite to that containing the sound record so as to bow said lm.

PETER LoHN.

AriFoNso CORTELLA.

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