US2115659A - Method of producing synthetic musical sounds - Google Patents

Description

April 26, 1938. a. WIENECKE 2,115,659

METHOD OF PRODUCING SYNTHETIC MUSICAL SOUNDS Filed Feb. 17, 1934 I Patented Apr. 26, 1 938 .ApplicationmFebrnary TATEs PATENT OFFICE-- mrrnon or raonucma smns'ri I mJsrosLsormns Bruno Wienecke, Berlin, Germany 17, 1934, Serial No. 711,655

Germany March 6, 1983 lclalms.

This invention relatesto-a method of and apparatus for producing synthetic musical sounds.

In the past few years methods have been devised having the object of producing the sound record provided on a sound film in the form of periodical blackened portions, not through the medium of microphone and amplifier, but in immediate fashion by the photographical recordal of corresponding drawings.

Preferably these drawings are a direct representation of the single oscillation curves approximately of the kind whichv are produced-on reduced scale-on a second film according to the amplitude process.

Naturally full scope is available for devising new forms of curves, and in following this procedure the observation has been made that sound structures or combinations may be produced, which are peculiar in their nature,.and heretofore have not been capable of being produced in direct fashion by any form of musical instrument. It will thus be obvious that by .the additional developmentof these methods the prospect is obtained of opening up new fields of musical sound which previously were in no way available.

It will readily be appreciated that the method of producing the single oscillations of a sound wave in the form of a drawing is extremely tedious and requires a considerable Thus, for example, a tone of 800 amount of time. periods intended to endure, say, for 5 seconds would require 4000 single oscillations.

It is an essential feature of the method according to the invention that all of the numerous possibilities of variation inherent in principle in this method, more particularly ation in the form of the curve,

as regards variare not in any way obstructed as occurs in connection with other methods hitherto known.

The method according to the present invention proceeds in the first place from an image of an oscillation, which may be. obtained, for

peculiar to the invention as described later, and

example, by drawing by handjor by the method which for the purpose of the further description I prefer-to term the "shape".- This single oscillation is transmitted photographically in the correct size to the film by the use of suitable optical means, the film being advanced continuously and the image or shape exposed for a brief space of time. The rate ofmovement of the film must be in such relation to the number of exposures that the single reco'rdals on the to follow each other without overlapping and without intermediate spacing. Assuming it is desired to reco film are caused rd an oscillation of a tone of diifer'ent pitch, it is necessary in accordance with existing methods to draw a new curve comprising a correspondingly greater number of oscillations per unit of length. According to the invention, however, the shape or basic 5 curve is not altered, but the plane of the film and the plane of the board or sheet on which the shape is drawn are merely rotated in relation to each other. This is preferably performed by rotating the said board or sheet about an axis 10 vertical to thedirection of movement of the film.

By reason of this rotation the length of the shape is shortened perspectively, so that the reproduction thereof on'the film will also be shorter. To preclude gaps between the single repro- 15 ductions the speed of the film must be changed (decreased) accordingly.

With correct adaptation of the angle of rotation of the shape board or sheet to the advance movement of the film and the number of exposures there is again produced on the film a connective series of curves which, however, now comprise a different number of oscillations for a certain length of film, and accordingly will result in a different tone upon the reproduction; According to one form of embodiment of the invention it is possible, instead of directly photographing the drawing or shape, to photograph an image of the curve or shape produced optically, for example by projection. In this case it is possible to twist the plane of the curve or shape in relation to the plane of the projection surface, and thus to'obtain optical distortion of the film image. It is also possible to twist both the original curve or shape as well as the surface of the film in relation to the projected image of the shape, in which case the extent of distortion may be doubled. The optical distortion may also be accomplished by the interposition of cylinder lenses or cylindrical reflectors. It is also 40 possible to project a plurality of basic curves or shapes on to a screen simultaneously, and thus superpose different frequencies.

The invention will now be described more fully with reference to the accompanying drawing, in 46 which v Fig. 1 is a perspective view'of a possible form of embodiment of the apparatus for carrying the invention into eifect.

Fig. 2 represents a form of embodiment of the 50 curve board I in Fig. 1, comprising an elastic band, the form of which may be varied as desired with the assistance of a keyboard. For producing contrast between the surfaces above and below the band there are secured to the lower side 05 of the band dark overlapping strips of material.

Fig. 3 shows a modified form of embodiment of the curve board on enlarged scale. .In this case the surface of the board comprises a plurality of prismatic rods or bars situated close together and having their upper ends colored white and their lower ends colored black, the relative position of these bars being adjustable by means of a keyboard.

Fig. 4 shows an arrangement for reducing the invention to practice, having the object of converting the image of the curve into sound in direct fashion without the medium of a film.

Referring now to the drawing, i is the board or sheet bearing the basic curve or shape. This board or sheet is rigidly connected to the fixed shaft 2. The basic curve or shape i is lighted by the lamp 3. The rays of light reflected by the light portions of the basic curve or shape pass to a certain extentthrough the slot 4 in the disk 5, and are projected by the lens 6 on to the light-sensitive film I. From the dark portions no light passes to-thecorresponding points of the film, so that on the latter there is produced a natural reproduction of the ciirve on the table I, preferably on reduced scale.

The lens is an ordinary photographic lens having a short focal distance, similar to the lenses of film cameras. The form of the lens is well known in the art, and does not constitute part of the invention as claimed.

The film is situated in a light-proof chamber, in the side of which directed towards the board or table I there is located the lens 8. The film I is advanced by the toothed drum 8, which is also situated within the chamber. This drum'is driven by the motor l through the medium of the shaft 62 and the worm gear 9. The motor In also drives by means of a belt and a pulley 85 the conical drum ll,.which is made to contact with a second conical drum H, the jacket of which, however, in contradistinction to the drum H, is curved in slightly convex fashion, so that the two drums touch each other only at one point. The shaft of the drum [2 drives through the medium of'the belt pulleys l3 and I4 the shaft l5 having mounted thereon the slotted disk- 5. The drums ll and i2 constitute a gear for varying the number of revolutions without any break. The variation in the speed takes place by rocking the shaft of the drum II, which shaft for this purpose is mounted to turn in the shiftable bearings II. By themovement of the shaft of the drum I! the point of contact between the two drums is caused to move from the one end to the other, the contacting peripheries accordingly varying in size. The bearings 85 for the drum are connected immovably with the base plate I 9, whilst the bearings 68 (Fig. 1) for the drum I! may be shifted parallel to the base plate along slideways It and II. By reason of this displacement alteration is effected in the point of contact 61 between the two drums.

If the shaft 64 of the drum is moved into the one extreme, the point of contact 61 is located at the left-hand end of the drums. In this posizqssugoou I as the two ends of each drum possess different diameters. The jacket of the drum ll represents a straight line. On the other hand the jacket line of the drum I2 is curved outwardly. The curvature of If is arcuate in form. This jacket line, however, may also be parabolic or of other suitable form.

The drum l i is the operating drum, and I2 the driven drum. Vice versa the power might also be transmitted from l2 to H, i. e., from a convex conical to a straight conical or even concave conical drum. There would also be no objection to making both drumsin convex conical form, the radius of curvature being made to vary.

Although in the following for the sake of brevity reference will be made to conical drums, this term will be understood to include any of the forms referred to in the above.

The movement on the part of the shaft of the drum I! (Fig. l) is caused by the fact that the extended bearing I'I contacts with a cam. ll. The cam I8 is firmly connected to the shaft 2. About the rigid shaft 2 there is also provided in rotatable fashion the complete arrangement insofar as the same is mounted on the base plate ID.

The gear comprising the conical drums II and I2 possesses considerable advantages in face of the previously known embodiments having straight jacket surfaces.

Straight drums of this nature require to be connected by means of a coupling member, which'consists, for example,'of a driving belt or a roller. To vary the transmission ratio this coupling member must be dis-,

placed by a threaded spindle. This displacement cannot be performed very rapidly, so that a considerable amount of time is lost if thetransmission ratio is varied very frequently. In the embodiment having curved jacket lines according to the invention the transmission ratio may be altered quickly and easily by slight movement of the shaft of the one drum in a lateral direction, as set forth in the following description of on the film will possess its maximum length.

The disk I having the slot 4 acts as a photographic diaphragm, which allows the-light proceeding from the board or sheet. I to act on the film for a space of time as short as possible, i. e., the time required by the slot to scan the curve once must be so short that the advance of the film taking place at the same time does not result in any appreciable lack of sharpness or distortion of the reproduction. This is important if the film. as shown, is moved continuously. If the film is moved intermittently, the time of exposure may naturally be extended without unduly affec ing the sharpness of the image.

The operating mechanism is so adjusted that upon each revolution of the disk. 5 the film is advanced to an extent representing the, length of the image of the curve or shape on the film, so that on the film there is produced a continuous series of reproductions of the curve or shape on the board or sheet I The parallel disposal of the board or sheet I .and the film as described results in the smallest number of reproductions per length of film, and accordingly in the lowest tone. To produce a higher tone the plate i9 together with the total apparatus including the film I is turned about the shaft 2, so that the surface of the sheet or board i, which is not moved conjointly is not parallel to the plane of .the film. The reproduction of the shape on the film will accordingly be shorter. If the rate of movement of the film were not altered, spaces would result on the film between the single recordals, and the tone would not be pure. For this reason there is provided the cam l8, which does not rotate together with the plate I, but by reason of the movement displaces the bearing 11 of the drum I! in such fashion that in accordance with the shortened'reproduction on the film the number of exposures is also increased by increasing the circumferential velocity of the disk 5. This increase in the number of exposures is such that the single reproductions on the film follow each other without intermediate spacing. There is accordingly again formed a continuous series of curves which, however, comprises a greater number of reproductions per unit of length and accordingly results in a higher tone when passed through an ordinary sound fil'm projector. The turning-of the plate'l may be performed, for example, by the foot of the operator, as indicated in Fig. 1 by the double-headed arrow 5|.

Preferably, operations will be performed at a reduced speed, similar to the quick run exposures in kinematograph films, so that in connection with the higher. tones the speed of the apparatus will not become excessive.

In order that a proper idea of the nature of the tone may be obtained before the record is made on the film, there is provided in the path of the rays of light the reflector 20.

An additional feature of the invention is the rapid production of different forms of curves.

This is accomplished by the fact that the curve or shape is constructed as a tangible element, the form of which may be changed mechanically. For example, an elastic band composed of rubber, steel or the like may act as marginal line for the curve, the form of which may be readily changed by being bent or curved in diil'erentfashion by a keyboard by the useof pins, levers or the like. A possible form of embodiment of this arrangement is illustratedin Fig. 2. In this case 3| is the elastic band, which is tensioned firmly at and ll. 34 are the pins, the ends of which are connected firmly with the band. The pins 34 are moved by means of the levers 35 constructed to form keys and rotatably mounted on the shaft 36.

This might be performed, for examplaby attaching to the elastic band narrow strips 31 of a dark material, in such a manner that the same hang down and thus cause the surface below the band to appear dark as compared with the visible, for example white background above the band.

vIi these strips of material were made so wide as An additional example of a mechanically variable curve is shown in Fig. 3. A number of small narrow bars 4! are situated close together so as to form a surface. The bars, as indicated, are colored over the one half black and over the other half white. Each bar is connected by means of levers with the keyboard 42, and may be lifted or lowered by actuation of the key. In this manner the bounding line 43-44 between the black and the white portion of each bar is shifted within the surface formed. By variable depression the bounding line may be varied to produce a desired form of curve, as illustrated in the drawing. The greater the number of bars, the greater are the degrees of fineness of the curve which may be produced. For fixing the curve according to Fig. 1 a photographic recordal is made on a film of the bounding line between black and white in the manner indicated above.

Immediate reproduction of the sound without the use of a film may be performed, according to the invention, by means of an apparatus such as shown in Fig. 4.

In a circular drum 5i having about its periphery a number of slots 52 there is located a lamp '53, the light of which is concentrated by a collecting lens 54 to a part of the inner wall of the drum. The light passing through the slots is projected through the lens 55 on to the sheet or board 55. The drum 5| is set into rapid motion, so that the single beams of light are passed in rapid succession over the board 56. The distance between the board 56 on the one hand and the drum 5! and objective 55 on the other hand is such that on each occasion only the light from the one slot impinges against the board. Immediately the one beam of light moves away from the board on the one side the next beam of light appears on the other side.

' The light reflected by the light portions of the board meets against the reflector 51 which contains the photo-cell 58. The photo-electric currents produced are conducted over the amplifier 59 to the loudspeaker 60, where the same are made audible. In this arrangement the pitch of the tone produced is'determined by the number of revolutions of the drum, while the tone itself is determined in the manner already described by mechanical alteration of movable parts of the board 56. In order to produce rapid variations in the pitch it is possible in accordance with the invention to provide a plurality of slotted drums, which revolve at different speeds and are so arranged that their beams of light all impinge against the same board.

By shading off the single rays of light it is possible to produce different frequencies very quickly. It is also possible to make provision at will for diiferent frequencies simultaneously. The intensity of the sound may be varied by different degrees of illumination of the board or sheet, or by the provision of light filters in front of the photo-cell or the film.

Reference has already been made to the possibility of the basic curve or shape being scanned not in direct fashion by the rays of light, but through the medium of an image thereof. This image may be obtained, for example, by the dia- .scopic or episcopic projection of one or more (different) basic curves or shapes. In the case of direct reproduction by means of photo-cell this projected image naturally cannot be scanned by rays of light according to the method illustrated in Fig. 4. In this case it is necessary, by means of a movable slotted diaphragm, to allow a part of the light from the total image to fall on to a photocell. In the embodiment according to Fig. 4 the photo-cell might be provided-within the drum 5! in place of the lamp 53. The board or sheet 5% would then form the projection surfacefor the basic curve or shape.

What I claim as new and desire to secure by Letters Patent is:

1. In an apparatus for making synthetic sound records adapted for use in sound-reproducing apparatus, a light-sensitive surface, a variable structure disposed over a plane and representing a. single oscillation of the sound to be produced, means for producing in successive order single records of the said structure on the said surface, means for varying the form of the said structure in any desired order, and means for varying the plane of the said structure with respect to the plane of the said surface.

2. In an apparatus for making synthetic sound records adapted for use in sound-reproducing apparatus, a light-sensitive surface, a variable structure comprising a plurality of adjacently disposed and relatively shiftable rods, means for shifting the said rods so as to cause them'to assume any desired position with respect to one another, and means for producing in successive order single records of the said structure on the light-sensitive surface representing a continuous record of the desired tone.

3. In an apparatus for making synthetic sound records adapted for use in sound-reproducing apparatus, a photographic film, a variable structure comprising a plurality of adjacently disposed and relatively shiitable rods forming a desired figure, means for shifting the said rods so as to cause them to assume any desired position with respect to one another, means for producing in successive order single records of the said figure on the said film, means for advancing the said film after each single record by an amount exactly equal to the length of a single record on the said film,

means for varying the plane'of the said structure in relation to the plane of the film, and means for varying the rate of movement of the said film consistent with variations in the number of records produced per unit of time.

' 4. A method of making sound records adapted for use in sound-reproducing apparatus, which consists inpreparing a basic figure representing a single oscillation of the tone to be produced and extending over a plane, producing in successive order single records of the said figure on a lightsensitive surface whilst at the same time advancing the said surface after each record has been made by an amount exactly equal to the length of a single record on the said surface,

varying the form of the said figure to assume any the plane of the light-sensitive surface in order to vary the length of the single records produced on the said surface. I

BRUNO WIENECK E.

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